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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.

  2. Direct imaging of explosives.

    PubMed

    Knapp, E A; Moler, R B; Saunders, A W; Trower, W P

    2000-01-01

    Any technique that can detect nitrogen concentrations can screen for concealed explosives. However, such a technique would have to be insensitive to metal, both encasing and incidental. If images of the nitrogen concentrations could be captured, then, since form follows function, a robust screening technology could be developed. However these images would have to be sensitive to the surface densities at or below that of the nitrogen contained in buried anti-personnel mines or of the SEMTEX that brought down Pan Am 103, approximately 200 g. Although the ability to image in three-dimensions would somewhat reduce false positives, capturing collateral images of carbon and oxygen would virtually assure that nitrogenous non-explosive material like fertilizer, Melmac dinnerware, and salami could be eliminated. We are developing such an instrument, the Nitrogen Camera, which has met experimentally these criteria with the exception of providing oxygen images, which awaits the availability of a sufficiently energetic light source. Our Nitrogen Camera technique uses an electron accelerator to produce photonuclear reactions whose unique decays it registers. Clearly if our Nitrogen Camera is made mobile, it could be effective in detecting buried mines, either in an active battlefield situation or in the clearing of abandoned military munitions. Combat operations require that a swathe the width of an armored vehicle, 5 miles deep, be screened in an hour, which is within our camera's scanning speed. Detecting abandoned munitions is technically easier as it is free from the onerous speed requirement. We describe here our Nitrogen Camera and show its 180 pixel intensity images of elemental nitrogen in a 200 g mine simulant and in a 125 g stick of SEMTEX. We also report on our progress in creating a lorry transportable 70 MeV electron racetrack microtron, the principal enabling technology that will allow our Nitrogen Camera to be deployed in the field.

  3. Direct Imaging of Giant Exoplanets

    NASA Astrophysics Data System (ADS)

    Tamura, Motohide

    Since the first detection of exoplanets around a Sun-like star 51 Peg in 1995, their detection and characterization are mainly led by indirect methods such as radial velocity and transit methods. However, recent progresses of observational techniques have finally enabled the direct imaging observations of giant planets of solar-system-scale orbit (with their semi-major axes less than about 50 AU) around A-type stars (e.g., Marois et al. 2008, 2010) and G-type stars (e.g., Kuzuhara et al. 2013). Direct imaging is useful to obtain the physical and atmospheric parameters of exoplanets. In fact not only colors but also a medium-resolution spectroscopy of such planets has been successfully obtained for their atmospheric characterization (Barman et al. 2013). Their masses are typically a few to ~10 Jupiter masses and they orbit at a Saturn- to-Pluto distance. Therefore, like hot-Jupiters and super-Earths they are unlike any solar-system planets, and called wide-orbit giant planets. A recent large search for planets and disk on the Subaru 8.2-m telescope (SEEDS project) has detected a 3-5 Jupiter-masses planet around a Sun-like star GJ 504 (Kuzuhara et al. 2013). It is the coolest planetary companion so far directly imaged and its near-infrared color is “bluer” than that of other directly imaged planets. In this contribution, I will review the recent progresses on direct imaging of exoplanets, highlight the results of the SEEDS project, and discuss the future developments.

  4. Direct Thrombus Imaging in Stroke

    PubMed Central

    Kim, Jongseong; Park, Jung E.; Nahrendorf, Matthias; Kim, Dong-Eog

    2016-01-01

    There is an emergent need for imaging methods to better triage patients with acute stroke for tissue-plasminogen activator (tPA)-mediated thrombolysis or endovascular clot retrieval by directly visualizing the size and distribution of cerebral thromboemboli. Currently, magnetic resonance (MR) or computed tomography (CT) angiography visualizes the obstruction of blood flow within the vessel lumen rather than the thrombus itself. The present visualization method, which relies on observation of the dense artery sign (the appearance of cerebral thrombi on a non-enhanced CT), suffers from low sensitivity. When translated into the clinical setting, direct thrombus imaging is likely to enable individualized acute stroke therapy by allowing clinicians to detect the thrombus with high sensitivity, assess the size and nature of the thrombus more precisely, serially monitor the therapeutic effects of thrombolysis, and detect post-treatment recurrence. This review is intended to provide recent updates on stroke-related direct thrombus imaging using MR imaging, positron emission tomography, or CT. PMID:27733029

  5. Directional synthetic aperture flow imaging.

    PubMed

    Jensen, Jørgen Arendt; Nikolov, Svetoslav Ivanov

    2004-09-01

    A method for flow estimation using synthetic aperture imaging and focusing along the flow direction is presented. The method can find the correct velocity magnitude for any flow angle, and full color flow images can be measured using only 32 to 128 pulse emissions. The approach uses spherical wave emissions with a number of defocused elements and a linear frequency-modulated pulse (chirp) to improve the signal-to-noise ratio. The received signals are dynamically focused along the flow direction and these signals are used in a cross-correlation estimator for finding the velocity magnitude. The flow angle is manually determined from the B-mode image. The approach can be used for both tissue and blood velocity determination. The approach was investigated using both simulations and a flow system with a laminar flow. The flow profile was measured with a commercial 7.5 MHz linear array transducer. A plastic tube with an internal diameter of 17 mm was used with an EcoWatt 1 pump generating a laminar, stationary flow. The velocity profile was measured for flow angles of 90 and 60 degrees. The RASMUS research scanner was used for acquiring radio frequency (RF) data from 128 elements of the array, using 8 emissions with 11 elements in each emission. A 20-micros chirp was used during emission. The RF data were subsequently beamformed off-line and stationary echo canceling was performed. The 60-degree flow with a peak velocity of 0.15 m/s was determined using 16 groups of 8 emissions, and the relative standard deviation was 0.36% (0.65 mm/s). Using the same setup for purely transverse flow gave a standard deviation of 1.2% (2.1 mm/s). Variation of the different parameters revealed the sensitivity to number of lines, angle deviations, length of correlation interval, and sampling interval. An in vivo image of the carotid artery and jugular vein of a healthy 29-year-old volunteer was acquired. A full color flow image using only 128 emissions could be made with a high

  6. Direct imaging of photonic nanojets.

    PubMed

    Ferrand, Patrick; Wenger, Jérôme; Devilez, Alexis; Pianta, Martina; Stout, Brian; Bonod, Nicolas; Popov, Evgueni; Rigneault, Hervé

    2008-05-12

    We report the direct experimental observation of photonic nanojets created by single latex microspheres illuminated by a plane wave at a wavelength of 520 nm. Measurements are performed with a fast scanning confocal microscope in detection mode, where the detection pinhole defines a diffraction-limited observation volume that is scanned in three dimensions over the microsphere vicinity. From the collected stack of images, we reconstruct the full 3 dimensional photonic nanojet beam. Observations are conducted for polystyrene spheres of 1, 3 and 5 microm diameter deposited on a glass substrate, the upper medium being air or water. Experimental results are compared to calculations performed using the Mie theory. We measure nanojet sizes as small as 270 nm FWHM for a 3 microm sphere at a wavelength lambda of 520 nm. The beam keeps a subwavelength FWHM over a propagation distance of more than 3 lambda, displaying all the specificities of a photonic nanojet.

  7. 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

  8. Future Directions for Astronomical Image Display

    NASA Technical Reports Server (NTRS)

    Mandel, Eric

    2000-01-01

    In the "Future Directions for Astronomical Image Displav" project, the Smithsonian Astrophysical Observatory (SAO) and the National Optical Astronomy Observatories (NOAO) evolved our existing image display program into fully extensible. cross-platform image display software. We also devised messaging software to support integration of image display into astronomical analysis systems. Finally, we migrated our software from reliance on Unix and the X Window System to a platform-independent architecture that utilizes the cross-platform Tcl/Tk technology.

  9. 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.

  10. Future directions for positive body image research.

    PubMed

    Halliwell, Emma

    2015-06-01

    The emergence of positive body image research during the last 10 years represents an important shift in the body image literature. The existing evidence provides a strong empirical basis for the study of positive body image and research has begun to address issues of age, gender, ethnicity, culture, development, and intervention in relation to positive body image. This article briefly reviews the existing evidence before outlining directions for future research. Specifically, six areas for future positive body image research are outlined: (a) conceptualization, (b) models, (c) developmental factors, (d) social interactions, (e) cognitive processing style, and (f) interventions. Finally, the potential role of positive body image as a protective factor within the broader body image literature is discussed.

  11. 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

  12. Directional imaging of the retinal cone mosaic.

    PubMed

    Vohnsen, Brian; Iglesias, Ignacio; Artal, Pablo

    2004-05-01

    We describe a near-IR scanning laser ophthalmoscope that allows the retinal cone mosaic to be imaged in the human eye in vivo without the use of wave-front correction techniques. The method takes advantage of the highly directional quality of cone photoreceptors that permits efficient coupling of light to individual cones and subsequent detection of most directional components of the backscattered light produced by the light-guiding effect of the cones. We discuss details of the system and describe cone-mosaic images obtained under different conditions.

  13. Future Directions for Astronomical Image Display

    NASA Technical Reports Server (NTRS)

    Mandel, Eric

    1997-01-01

    In our "Future Directions for Astronomical Image Display" project, the Smithsonian Astrophysical Observatory (SAO) and the National Optical Astronomy Observatories (NOAO) will evolve our existing image display software into a fully extensible, cross-platform image display server that can run stand-alone or be integrated seamlessly into astronomical analysis systems. We will build a Plug-in Image Extension (PIE) server for astronomy, consisting of a modular image display engine that can be customized using "plug-in" technology. We will create plug-ins that reproduce all the current functionality of SAOtng. We also will devise a messaging system and a set of distributed, shared data objects to support integrating the PIE server into astronomical analysis systems. Finally, we will migrate our PIE server, plug-ins, and messaging software from Unix and the X Window System to a platform-independent architecture that utilizes cross-platform technology such as Tcl/Tk or Java.

  14. Discrete directional wavelet bases for image compression

    NASA Astrophysics Data System (ADS)

    Dragotti, Pier L.; Velisavljevic, Vladan; Vetterli, Martin; Beferull-Lozano, Baltasar

    2003-06-01

    The application of the wavelet transform in image processing is most frequently based on a separable construction. Lines and columns in an image are treated independently and the basis functions are simply products of the corresponding one dimensional functions. Such method keeps simplicity in design and computation, but is not capable of capturing properly all the properties of an image. In this paper, a new truly separable discrete multi-directional transform is proposed with a subsampling method based on lattice theory. Alternatively, the subsampling can be omitted and this leads to a multi-directional frame. This transform can be applied in many areas like denoising, non-linear approximation and compression. The results on non-linear approximation and denoising show very interesting gains compared to the standard two-dimensional analysis.

  15. 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…

  16. 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.

  17. 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.

  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. 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.

  20. 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.

  1. Medical imaging at risk from European directive

    NASA Astrophysics Data System (ADS)

    Keevil, Stephen

    2009-09-01

    The recent Forum article by Denis Le Bihan ("Threats to ultra-high-field MRI" August pp16-17) is a valuable addition to the ongoing debate about the impact on magnetic resonance imaging (MRI) of the European Commission's Physical Agents (EMF) directive. When this directive was introduced in 2004, exposure limits for static magnetic fields were excluded, because it was known that guidance published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) in 1994 was being revised. It is likely that the new ICNIRP guidelines, to which Le Bihan refers, will now be incorporated into the directive. If so, this could indeed impact on ultra-highfield MRI, in which Europe has a worldleading position.

  2. 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

  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. 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

  5. Polaroid Graphics Imaging Direct Digital Color Proofing

    NASA Astrophysics Data System (ADS)

    King, Patrick F.

    1989-04-01

    Good morning ladies and gentlemen. I represent Polaroid Graphics Imaging, a wholly owned subsidiary of the Polaroid Corporation. We wish to thank Ken Cloud and the SPIE for the opportunity to speak today. Several criterion are fundamental in the role for Direct Digital Color Proofing (DDCP), First, the DDCP must represent a first generation hardcopy of the exact color information in the production stream. If must, as it's name suggests be an exact, proof (hence the name direct) of the electronic or digital information which would otherwise be directed toward film working. It is after all the most critical means to evaluate the quality of whatever pagination, scanner or color work which has gone be for it. Second, the DDCP must represent an opportunity. That opportunity is to reconvene the production stream and move to film making, optical or magnetic storage, or satellite transmission with the confidence that the DDCP is identical to some conventional counterpart. In the case of film it must match a conventional proof and press sheet, dot for dot. Otherwise it is merely an exercise in interpretation. For magnetic or optical storage and satellite transmission there must be assurance that at any opportunity either a duplicate DDCP or a conventional film/proof could reproduce earlier results. Finally as the printed product is the final goal and direct to press is evolving in direct to plate and direct to gravure printing the DDCP must share the half toner lineage of these products. Thirdly and hardly least, the whole purpose for DDCP is increased productivity. However, our industry struggles to maintain individuality and variety. Somehow DDCP must balance these forces.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Direct imaging of localized surface plasmon polaritons

    NASA Astrophysics Data System (ADS)

    Balci, Sinan; Karademir, Ertugrul; Kocabas, Coskun; Aydinli, Atilla

    2011-09-01

    In this Letter, we report on dark field imaging of localized surface plasmon polaritons (SPPs) in plasmonic waveguiding bands formed by plasmonic coupled cavities. We image the light scattered from SPPs in the plasmonic cavities excited by a tunable light source. Tuning the excitation wavelength, we measure the localization and dispersion of the plasmonic cavity mode. Dark field imaging has been achieved in the Kretschmann configuration using a supercontinuum white-light laser equipped with an acoustooptic tunable filter. Polarization dependent spectroscopic reflection and dark field imaging measurements are correlated and found to be in agreement with finite-difference time-domain calculations.

  11. Distance informed Track-Weighted Imaging (diTWI): a framework for sensitising streamline information to neuropathology.

    PubMed

    Bell, Christopher; Pannek, Kerstin; Fay, Michael; Thomas, Paul; Bourgeat, Pierrick; Salvado, Olivier; Gal, Yaniv; Coulthard, Alan; Crozier, Stuart; Rose, Stephen

    2014-02-01

    Track-Weighted Imaging (TWI), where voxel intensity is based on image metrics encoded along streamline trajectories, provides a mechanism to study white matter disease. However, with generalised streamline weighting, it is difficult to localise the precise anatomical source and spread of injury or neuropathology. This limitation can be overcome by modulating the voxel weight based on the distance of the voxel from a given anatomical location along the tract, which we term diTWI: distance informed Track-Weighted Imaging. The location of known neuropathology can be delineated on any given imaging modality (e.g. MRI or PET). To demonstrate the clinical utility of this approach, we measured tumour cell infiltration along WM fibre tracts in 13 patients with newly diagnosed glioblastoma and 1 patient with Anaplastic Astrocytoma. TWI and diTWI maps were generated using information obtained from dynamic contrast enhanced MRI (area under the curve, AUC) and diffusivity maps (ADC and FA) with tumour boundaries automatically extracted using a logistic regression classifier. The accuracy of the derived tumour volumes was compared to those generated using 3,4-dihydroxy-6-[(18)F]-fluoro-l-phenylalanine (FDOPA) PET imaging. The accuracy of the tumour volumes generated from the diTWI maps was superior to volumes derived from the TWI, geometric distance or baseline AUC, FA and ADC maps. The relative overlap and relative dissimilarity rates for the diTWI generated tumour volumes after classification were found to be 82.3±15.3% (range 69.1-91.9) and 16.9±8.8% (range 7.9-37.5), respectively. These findings show that diTWI maps provide a useful framework for localising neuropathological processes occurring along WM pathways.

  12. Pixel extraction based integral imaging with controllable viewing direction

    NASA Astrophysics Data System (ADS)

    Ji, Chao-Chao; Deng, Huan; Wang, Qiong-Hua

    2012-09-01

    We propose pixel extraction based integral imaging with a controllable viewing direction. The proposed integral imaging can provide viewers three-dimensional (3D) images in a very small viewing angle. The viewing angle and the viewing direction of the reconstructed 3D images are controlled by the pixels extracted from an elemental image array. Theoretical analysis and a 3D display experiment of the viewing direction controllable integral imaging are carried out. The experimental results verify the correctness of the theory. A 3D display based on the integral imaging can protect the viewer’s privacy and has huge potential for a television to show multiple 3D programs at the same time.

  13. Role of Imaging and Cytogenetics in Evaluation of DiGeorge Syndrome - A Rare Entity in Clinical Practice.

    PubMed

    Ramachandran, Rajoo; Babu, Sellappan Rajamanickam; Ilanchezhian, Subramanian; Radhakrishnan, Prabhu Radhan

    2015-01-01

    DiGeorge syndrome is a congenital genetic disorder that affects the endocrine system, mainly the thymus and parathyroid glands. The syndrome produces different symptoms, which vary in severity and character between patients. It manifests with craniofacial dysmorphism and defects in the heart, parathyroid, and thymus. Patients can present with a palatal deformity and nasal speech. This rare entity is caused mainly due to deletion of chromosome 22q11.2. Radiographic evaluation of DiGeorge syndrome is necessary to define aberrant anatomy, evaluate central nervous system, craniofacial abnormalities, musculoskeletal system, and cardiothoracic contents. It also helps in planning surgical procedures and surgical reconstructions. We report a case of DiGeorge syndrome in a 4-month-old neonate and discuss the clinical, imaging, and cytogenetic findings that helped in the diagnosis of this rare entity.

  14. Synthesis of Phenanthrothiazoles and 1,2-Di(heteroaryl)benzenes through Successive Pd-Catalyzed Direct Arylations.

    PubMed

    Shi, Xinzhe; Soulé, Jean-François; Doucet, Henri

    2017-03-15

    Palladium-catalyzed direct arylation of 4-(2-bromophenyl)-2-methylthiazole proceeds with high efficiency at the thiazolyl C5 position using aryl bromides as the aryl source. This transformation provides simple access to 4-(2-bromophenyl)-2-methyl-5-arylthiazoles, which can be further converted into phenanthrothiazoles via palladium-catalyzed intramolecular direct arylation. When the direct arylation of 4-(2-bromophenyl)-2-methyl-5-arylthiazoles is conducted in the presence of an external heteroarene such as thiazoles, thiophenes, or imidazo[1,2-a]pyridines, the intermolecular arylation of such external heteroarenes proceeds faster than the intramolecular reaction, allowing the formation of 1,2-di(heteroaryl)benzene derivatives.

  15. Current challenges and future directions in cardiac imaging

    PubMed Central

    Wann, Samuel; Tunio, Javed

    2010-01-01

    Imaging is one of the most important accomplishments of medicine during the last 1000 years. The contribution of modern imaging to progress in the delivery of health care is unquestioned. However, we need to refine our use of imaging, limiting its use to those occasions when it can contribute directly or indirectly to improving and lengthening the lives of patients. Technology prowess in imaging alone is not sufficient to deliver value to individuals or to society. Continued investment in imaging technology requires critical appraisal of its use in clinical decision making and patient outcomes. PMID:23960604

  16. 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.

  17. Directional bilateral filters for smoothing fluorescence microscopy images

    NASA Astrophysics Data System (ADS)

    Venkatesh, Manasij; Mohan, Kavya; Seelamantula, Chandra Sekhar

    2015-08-01

    Images obtained through fluorescence microscopy at low numerical aperture (NA) are noisy and have poor resolution. Images of specimens such as F-actin filaments obtained using confocal or widefield fluorescence microscopes contain directional information and it is important that an image smoothing or filtering technique preserve the directionality. F-actin filaments are widely studied in pathology because the abnormalities in actin dynamics play a key role in diagnosis of cancer, cardiac diseases, vascular diseases, myofibrillar myopathies, neurological disorders, etc. We develop the directional bilateral filter as a means of filtering out the noise in the image without significantly altering the directionality of the F-actin filaments. The bilateral filter is anisotropic to start with, but we add an additional degree of anisotropy by employing an oriented domain kernel for smoothing. The orientation is locally adapted using a structure tensor and the parameters of the bilateral filter are optimized for within the framework of statistical risk minimization. We show that the directional bilateral filter has better denoising performance than the traditional Gaussian bilateral filter and other denoising techniques such as SURE-LET, non-local means, and guided image filtering at various noise levels in terms of peak signal-to-noise ratio (PSNR). We also show quantitative improvements in low NA images of F-actin filaments.

  18. 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.

  19. Integration of multimodality images: success and future directions

    NASA Astrophysics Data System (ADS)

    Chen, Chin-Tu

    1993-07-01

    The concept of multi-modality image integration, in which images obtained from different sensors are co-registered spatially and various aspects of object characteristics revealed by individual imaging techniques are synergistically fused in order to yield new information, has received considerable attention in recent years. The initial success was made in visualizing integrated brain images which show the overlay of physiological information from PET or SPECT with anatomical information from CT or MRI, providing new knowledge of correlates of brain function and brain structure that was difficult to access previously. Extension of this concept to cardiac and pulmonary imaging is still in its infancy. One additional difficulty in dealing with cardiac/pulmonary data sets is the issue of motion. However, some features in periodic motion may offer additional information for the purpose of spatial co-registration. In addition to visualization of the fused image data in 2-D and 3-D, future directions in the arena of image integration from multiple modalities include multi-modal image reconstruction, multi-modal image segmentation and feature extraction, and other image analysis tasks that incorporate information available from multiple sources.

  20. 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

  1. Image compression with directional lifting on separated sections

    NASA Astrophysics Data System (ADS)

    Zhu, Jieying; Wang, Nengchao

    2007-11-01

    A novel image compression scheme is presented that the directional sections are separated and transformed differently from the rest of image. The discrete directions of anisotropic pixels are calculated and then grouped to compact directional sections. One dimensional (1-D) adaptive directional lifting is continuously applied along orientations of direction sections other than applying 1-D wavelet transform alternately in two dimensions for the whole image. For the rest sections, 2-D adaptive lifting filters are applied according to pixels' positions. Our single embedded coding stream can be truncated exactly for any bit rate. Experiments have showed that large coefficients can be significantly reduced along directional sections by our transform which makes energy more compact than traditional wavelet transform. Though rate-distortion (R-D) optimization isn't exploited, the PSNR is still comparable to that of JPEG-2000 with 9/7 filters at high bit rates. And at low bit rates, the visual quality is better than that of JPEG-2000 for along directional sections both blurring and ringing artifacts can be avoided and edge preservation is good.

  2. Adaptive directional lifting-based wavelet transform for image coding.

    PubMed

    Ding, Wenpeng; Wu, Feng; Wu, Xiaolin; Li, Shipeng; Li, Houqiang

    2007-02-01

    We present a novel 2-D wavelet transform scheme of adaptive directional lifting (ADL) in image coding. Instead of alternately applying horizontal and vertical lifting, as in present practice, ADL performs lifting-based prediction in local windows in the direction of high pixel correlation. Hence, it adapts far better to the image orientation features in local windows. The ADL transform is achieved by existing 1-D wavelets and is seamlessly integrated into the global wavelet transform. The predicting and updating signals of ADL can be derived even at the fractional pixel precision level to achieve high directional resolution, while still maintaining perfect reconstruction. To enhance the ADL performance, a rate-distortion optimized directional segmentation scheme is also proposed to form and code a hierarchical image partition adapting to local features. Experimental results show that the proposed ADL-based image coding technique outperforms JPEG 2000 in both PSNR and visual quality, with the improvement up to 2.0 dB on images with rich orientation features.

  3. Direct Imaging of Electron States in Open Quantum Dots

    NASA Astrophysics Data System (ADS)

    Aoki, N.; Brunner, R.; Burke, A. M.; Akis, R.; Meisels, R.; Ferry, D. K.; Ochiai, Y.

    2012-03-01

    We use scanning gate microscopy to probe the ballistic motion of electrons within an open GaAs/AlGaAs quantum dot. Conductance maps are recorded by scanning a biased tip over the open quantum dot while a magnetic field is applied. We show that, for specific magnetic fields, the measured conductance images resemble the classical transmitted and backscattered trajectories and their quantum mechanical analogue. In addition, we prove experimentally, with this direct measurement technique, the existence of pointer states. The demonstrated direct imaging technique is essential for the fundamental understanding of wave function scarring and quantum decoherence theory.

  4. 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

  5. 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

  6. Chromatic visualization of reflectivity variance within hybridized directional OCT images

    NASA Astrophysics Data System (ADS)

    Makhijani, Vikram S.; Roorda, Austin; Bayabo, Jan Kristine; Tong, Kevin K.; Rivera-Carpio, Carlos A.; Lujan, Brandon J.

    2013-03-01

    This study presents a new method of visualizing hybridized images of retinal spectral domain optical coherence tomography (SDOCT) data comprised of varied directional reflectivity. Due to the varying reflectivity of certain retinal structures relative to angle of incident light, SDOCT images obtained with differing entry positions result in nonequivalent images of corresponding cellular and extracellular structures, especially within layers containing photoreceptor components. Harnessing this property, cross-sectional pathologic and non-pathologic macular images were obtained from multiple pupil entry positions using commercially-available OCT systems, and custom segmentation, alignment, and hybridization algorithms were developed to chromatically visualize the composite variance of reflectivity effects. In these images, strong relative reflectivity from any given direction visualizes as relative intensity of its corresponding color channel. Evident in non-pathologic images was marked enhancement of Henle's fiber layer (HFL) visualization and varying reflectivity patterns of the inner limiting membrane (ILM) and photoreceptor inner/outer segment junctions (IS/OS). Pathologic images displayed similar and additional patterns. Such visualization may allow a more intuitive understanding of structural and physiologic processes in retinal pathologies.

  7. 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.

  8. Blind Source Separation Algorithms for PSF Subtraction from Direct Imaging

    NASA Astrophysics Data System (ADS)

    Shapiro, Jacob; Ranganathan, Nikhil; Savransky, Dmitry; Ruffio, Jean-Baptise; Macintosh, Bruce; GPIES Team

    2017-01-01

    The principal difficulty with detecting planets via direct imaging is that the target signal is similar in magnitude, or fainter, than the noise sources in the image. To compensate for this, several methods exist to subtract the PSF of the host star and other confounding noise sources. One of the most effective methods is Karhunen-Loève Image Processing (KLIP). The core algorithm within KLIP is Principal Component Analysis, which is a member of a class of algorithms called Blind Source Separation (BSS).We examine three other BSS algorithms that may potentially also be used for PSF subtraction: Independent Component Analysis, Stationary Subspace Analysis, and Common Spatial Pattern Filtering. The underlying principles of each of the algorithms is discussed, as well as the processing steps needed to achieve PSF subtraction. The algorithms are examined both as primary PSF subtraction techniques, as well as additional postprocessing steps used with KLIP.These algorithms have been used on data from the Gemini Planet Imager, analyzing images of β Pic b. To build a reference library, both Angular Differential Imaging and Spectral Differential Imaging were used. To compare to KLIP, three major metrics are examined: computation time, signal-to-noise ratio, and astrometric and photometric biases in different image regimes (e.g., speckle-dominated compared to Poisson-noise dominated). Preliminary results indicate that these BSS algorithms improve performance when used as an enhancement for KLIP, and that they can achieve similar SNR when used as the primary method of PSF subtraction.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Complex direct comb spectroscopy with a virtually imaged phased array.

    PubMed

    Scholten, Sarah K; Anstie, James D; Hébert, Nicolas Bourbeau; White, Richard T; Genest, Jérôme; Luiten, Andre N

    2016-03-15

    We demonstrate a simple interferometric technique to directly measure the complex optical transmittance over a large spectral range using a frequency-comb spectrometer based on a virtually imaged phased array. A Michelson interferometer encodes the phase deviations induced by a sample contained in one of its arms into an interferogram image. When combined with an additional image taken from each arm separately, along with a frequency-calibration image, this allows full reconstruction of the sample's optical transfer function. We demonstrate the technique with a vapor cell containing H13C14N, producing transmittance and phase spectra spanning 2.9 THz (∼23  nm) with ∼1 GHz resolution.

  16. 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.

  17. Subband directional vector quantization in radiological image compression

    NASA Astrophysics Data System (ADS)

    Akrout, Nabil M.; Diab, Chaouki; Prost, Remy; Goutte, Robert; Amiel, Michel

    1992-05-01

    The aim of this paper is to propose a new scheme for image compression. The method is very efficient for images which have directional edges such as the tree-like structure of the coronary vessels in digital angiograms. This method involves two steps. First, the original image is decomposed at different resolution levels using a pyramidal subband decomposition scheme. For decomposition/reconstruction of the image, free of aliasing and boundary errors, we use an ideal band-pass filter bank implemented in the Discrete Cosine Transform domain (DCT). Second, the high-frequency subbands are vector quantized using a multiresolution codebook with vertical and horizontal codewords which take into account the edge orientation of each subband. The proposed method reduces the blocking effect encountered at low bit rates in conventional vector quantization.

  18. Imaging diagnosis of dural and direct cavernous carotid fistulae*

    PubMed Central

    dos Santos, Daniela; Monsignore, Lucas Moretti; Nakiri, Guilherme Seizem; Cruz, Antonio Augusto Velasco e; Colli, Benedicto Oscar; Abud, Daniel Giansante

    2014-01-01

    Arteriovenous fistulae of the cavernous sinus are rare and difficult to diagnose. They are classified into dural cavernous sinus fistulae or direct carotid-cavernous fistulae. Despite the similarity of symptoms between both types, a precise diagnosis is essential since the treatment is specific for each type of fistula. Imaging findings are remarkably similar in both dural cavernous sinus fistulae and carotid-cavernous fistulae, but it is possible to differentiate one type from the other. Amongst the available imaging methods (Doppler ultrasonography, computed tomography, magnetic resonance imaging and digital subtraction angiography), angiography is considered the gold standard for the diagnosis and classification of cavernous sinus arteriovenous fistulae. The present essay is aimed at didactically presenting the classification and imaging findings of cavernous sinus arteriovenous fistulae. PMID:25741093

  19. Laser direct imaging of the printed electrical circuits on PCB

    NASA Astrophysics Data System (ADS)

    Barbucha, R.; Kocik, M.; Mizeraczyk, J.; Kozioł, G.; Borecki, J.

    2005-09-01

    The increasing demands for miniaturization and better functionality of electronic components and devices have a significant effect on the requirements facing the Printed Circuit Board (PCB) industry. PCB manufactures are driving for producing high density interconnect (HDI) boards at significantly reduced cost and reduced implementation time. The interconnection complexity of the PCB is still growing and today calls for 50/50 μm or 25/25 μm technology are real. Imaging of HDI boards poses a rapid increasing challenge on PCB manufactures due to line width and space getting smaller and mainly to tighter registration requirements. Existing technologies are unable to offer the acceptable solution. Nowadays the Laser Direct Imaging (LDI) technology is considered as an answer for these challenges. LDI is a process of imaging circuitry pattern directly on the PCB without the use of a phototool. The exposure of the photo-sensitive resist is carried out using a laser beam that is scanned across photoresist surface and switched on and off by means of a computer control system according to the electrical circuit pattern. Usually the laser used in the LDI generates the UV line, which is suitable for the commonly available photoresists. In this paper we present an introduction to LDI technology as well as an experiment consisted in an attempt to use a UV Nd:YAG laser (λ=355 nm) for direct imaging of conductive pattern on the PCB covered by photosensitive resist.

  20. SEEDS -- Direct Imaging Survey for Exoplanets and Disks

    NASA Astrophysics Data System (ADS)

    Helminiak, K. G.; Kuzuhara, M.; Kudo, T.; Tamura, M.; Usuda, T.; Hashimoto, J.; Matsuo, T.; McElwain, M. W.; Momose, M.; Tsukagoshi, T.

    2015-01-01

    Exoplanets on wide orbits (r ≳ 10 AU) can be revealed by high-contrast direct imaging, which is efficient for their detailed detections and characterizations compared with indirect techniques. The SEEDS campaign, using the 8.2-m Subaru Telescope , is one of the most extensive campaigns to search for wide-orbit exoplanets via direct imaging. Since 2009 to date, the campaign has surveyed exoplanets around stellar targets selected from the solar neighborhood, moving groups, open clusters, and star-forming regions. It also surveys exoplanets in planetary systems with debris disks . The survey is designed to perform observations of ˜500 stars, covering the age range of 1 Myr to a few Gyr. As a result of the observations performed so far, SEEDS has detected new sub-stellar companions , including planets with properties that are unique compared with the previously directly imaged exoplanets. High-contrast imaging by SEEDS has also provided better characterizations of exoplanet systems identified by indirect techniques.

  1. Mapping individual cosmid DNAs by direct AFM imaging.

    PubMed

    Allison, D P; Kerper, P S; Doktycz, M J; Thundat, T; Modrich, P; Larimer, F W; Johnson, D K; Hoyt, P R; Mucenski, M L; Warmack, R J

    1997-05-01

    Individual cosmid clones have been restriction mapped by directly imaging, with the atomic force microscope (AFM), a mutant EcoRI endonuclease site-specifically bound to DNA. Images and data are presented that locate six restriction sites, predicted from gel electrophoresis, on a 35-kb cosmid isolated from mouse chromosome 7. Measured distances between endonuclease molecules bound to lambda DNA, when compared to known values, demonstrate the accuracy of AFM mapping to better than 1%. These results may be extended to identify other important site-specific protein-DNA interactions, such as transcription factor and mismatch repair enzyme binding, difficult to resolve by current techniques.

  2. 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

  3. A novel approach to image neural activity directly by MRI

    NASA Astrophysics Data System (ADS)

    Singh, Manbir; Sungkarat, Witaya

    2005-04-01

    Though an approach to image the electrical activity of neurons directly by detecting phase shifts in MRI was first reported in 1991, results to-date remain equivocal due to the low signal-to-noise ratio. The objective of this work was to develop a stimulus-presentation and data acquisition strategy specially geared to detect phase-dispersion effects of neuronal currents within 10-100 ms following stimulation. The key feature is to set the repeated MR data acquisition time TR and the stimulus presentation interval (TI) slightly different from each other so that the time at which images are acquired shifts gradually from one acquisition to the next with respect to stimulus onset. For example, at TR=275ms and 4 Hz stimulus presentation (TI=250ms), initial synchronization of the stimulus onset and MR acquisition would result in the first image being acquired at a latency of 0+/- (temporal width of data acquisition window), second image at a latency of 25ms, third image at a latency of 50ms and so on up to a latency of 250ms, at which time the stimulus and data acquisition times would become re-synchronized to once again acquire an image at latency=0. Human data were acquired on a 1.5T GE EXCITE scanner from two 8mm thick contiguous slices bracketing the calcarine fissure during a checkerboard flashing at 4 Hz. Preliminary results show activity in the visual cortex at latencies consistent with EEG studies, suggesting the potential of this methodology to image neural activity directly.

  4. Direct Imaging of Laser-driven Ultrafast Molecular Rotation.

    PubMed

    Mizuse, Kenta; Fujimoto, Romu; Mizutani, Nobuo; Ohshima, Yasuhiro

    2017-02-04

    We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb explosion imaging setup in which a hitherto-impractical camera angle is realized. In our imaging technique, diatomic molecules are irradiated with a circularly polarized strong laser pulse. The ejected atomic ions are accelerated perpendicularly to the laser propagation. The ions lying in the laser polarization plane are selected through the use of a mechanical slit and imaged with a high-throughput, 2-dimensional detector installed parallel to the polarization plane. Because a circularly polarized (isotropic) Coulomb exploding pulse is used, the observed angular distribution of the ejected ions directly corresponds to the squared rotational wave function at the time of the pulse irradiation. To create a real-time movie of molecular rotation, the present imaging technique is combined with a femtosecond pump-probe optical setup in which the pump pulses create unidirectionally rotating molecular ensembles. Due to the high image throughput of our detection system, the pump-probe experimental condition can be easily optimized by monitoring a real-time snapshot. As a result, the quality of the observed movie is sufficiently high for visualizing the detailed wave nature of motion. We also note that the present technique can be implemented in existing standard ion imaging setups, offering a new camera angle or viewpoint for the molecular systems without the need for extensive modification.

  5. Image denoising using a directional adaptive diffusion filter

    NASA Astrophysics Data System (ADS)

    Zhao, Cuifang; Shi, Caicheng; He, Peikun

    2006-11-01

    Partial differential equations (PDEs) are well-known due to their good processing results which it can not only smooth the noise but also preserve the edges. But the shortcomings of these processes came to being noticed by people. In some sense, PDE filter is called "cartoon model" as it produces an approximation of the input image, use the same diffusion model and parameters to process noise and signal because it can not differentiate them, therefore, the image is naturally modified toward piecewise constant functions. A new method called a directional adaptive diffusion filter is proposed in the paper, which combines PDE mode with wavelet transform. The undecimated discrete wavelet transform (UDWT) is carried out to get different frequency bands which have obviously directional selectivity and more redundancy details. Experimental results show that the proposed method provides a performance better to preserve textures, small details and global information.

  6. 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

  7. RESOLVING THE DELTA ANDROMEDAE SPECTROSCOPIC BINARY WITH DIRECT IMAGING

    SciTech Connect

    Bottom, Michael; Mawet, Dimitri; Kuhn, Jonas; Mennesson, Bertrand; Shelton, Jean C.; Wallace, J. Kent; Serabyn, Eugene

    2015-08-10

    We present a direct image of the innermost companion to the red giant δ Andromedae using the Stellar Double Coronagraph at the Palomar Observatory. We use a Markov Chain Monte Carlo based algorithm to simultaneously reduce the data and perform astrometry and photometry of the companion. We determine that the companion is most likely a main sequence K-type star and is certainly not the previously hypothesized white dwarf.

  8. Fluorescence coupling for direct imaging of electrocatalytic heterogeneity.

    PubMed

    Guerrette, Joshua P; Percival, Stephen J; Zhang, Bo

    2013-01-16

    Here we report the use of fluorescence microscopy and closed bipolar electrodes to reveal electrochemical and electrocatalytic activity on large electrochemical arrays. We demonstrate fluorescence-enabled electrochemical microscopy (FEEM) as a new electrochemical approach for imaging transient and heterogeneous electrochemical processes. This method uses a bipolar electrode mechanism to directly couple a conventional oxidation reaction, e.g., the oxidation of ferrocene, to a special fluorogenic reduction reaction. The generation of the fluorescent product on the cathodic pole enables one to directly monitor an electrochemical process with optical microscopy. We demonstrate the use of this method on a large electrochemical array containing thousands or more parallel bipolar microelectrodes to enable spatially and temporally resolved electrochemical imaging. We first image molecular transport of a redox analyte in solution using an array containing roughly 1000 carbon fiber ultramicroelectrodes. We then carry out a simple electrocatalysis experiment to show how FEEM can be used for electrocatalyst screening. This new method could prove useful for imaging transient electrochemical events, such as fast exocytosis events on single and networks of neurons, and for parallel, high-throughput screening of new electrocatalysts.

  9. Two-direction nonlocal model for image denoising.

    PubMed

    Zhang, Xuande; Feng, Xiangchu; Wang, Weiwei

    2013-01-01

    Similarities inherent in natural images have been widely exploited for image denoising and other applications. In fact, if a cluster of similar image patches is rearranged into a matrix, similarities exist both between columns and rows. Using the similarities, we present a two-directional nonlocal (TDNL) variational model for image denoising. The solution of our model consists of three components: one component is a scaled version of the original observed image and the other two components are obtained by utilizing the similarities. Specifically, by using the similarity between columns, we get a nonlocal-means-like estimation of the patch with consideration to all similar patches, while the weights are not the pairwise similarities but a set of clusterwise coefficients. Moreover, by using the similarity between rows, we also get nonlocal-autoregression-like estimations for the center pixels of the similar patches. The TDNL model leads to an alternative minimization algorithm. Experiments indicate that the model can perform on par with or better than the state-of-the-art denoising methods.

  10. 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

  11. Susceptibility-weighted imaging: current status and future directions.

    PubMed

    Liu, Saifeng; Buch, Sagar; Chen, Yongsheng; Choi, Hyun-Seok; Dai, Yongming; Habib, Charbel; Hu, Jiani; Jung, Joon-Yong; Luo, Yu; Utriainen, David; Wang, Meiyun; Wu, Dongmei; Xia, Shuang; Haacke, E Mark

    2017-04-01

    Susceptibility-weighted imaging (SWI) is a method that uses the intrinsic nature of local magnetic fields to enhance image contrast in order to improve the visibility of various susceptibility sources and to facilitate diagnostic interpretation. It is also the precursor to the concept of the use of phase for quantitative susceptibility mapping (QSM). Nowadays, SWI has become a widely used clinical tool to image deoxyhemoglobin in veins, iron deposition in the brain, hemorrhages, microbleeds and calcification. In this article, we review the basics of SWI, including data acquisition, data reconstruction and post-processing. In particular, the source of cusp artifacts in phase images is investigated in detail and an improved multi-channel phase data combination algorithm is provided. In addition, we show a few clinical applications of SWI for the imaging of stroke, traumatic brain injury, carotid vessel wall, siderotic nodules in cirrhotic liver, prostate cancer, prostatic calcification, spinal cord injury and intervertebral disc degeneration. As the clinical applications of SWI continue to expand both in and outside the brain, the improvement of SWI in conjunction with QSM is an important future direction of this technology. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Direct and transgenerational effects of low doses of perinatal di-(2-ethylhexyl) phthalate (DEHP) on social behaviors in mice

    PubMed Central

    Snyder, Rodney W.; Sumner, Susan S.; Rissman, Emilie F.

    2017-01-01

    Di-(2-ethylhexyl) phthalate (DEHP) is an endocrine disrupting chemical commonly used as a plasticizer in medical equipment, food packaging, flooring, and children’s toys. DEHP exposure during early development has been associated with adverse neurobehavioral outcomes in children. In animal models, early exposure to DEHP results in abnormal development of the reproductive system as well as altered behavior and neurodevelopment. Based on these data, we hypothesized that developmental exposure to DEHP would decrease social interactions and increase anxiety-like behaviors in mice in a dose-dependent manner, and that the effects would persist over generations. C57BL/6J mice consumed one of three DEHP doses (0, 5, 40, and 400 μg/kg body weight) throughout pregnancy and during the first ten days of lactation. The two higher doses yielded detectable levels of DEHP metabolites in serum. Pairs of mice from control, low, and high DEHP doses were bred to create three dose lineages in the third generation (F3). Average anogenital index (AGI: anogenital distance/body weight) was decreased in F1 males exposed to the low dose of DEHP and in F1 females exposed to the highest dose. In F1 mice, juvenile pairs from the two highest DEHP dose groups displayed fewer socially investigative behaviors and more exploratory behaviors as compared with control mice. The effect of DEHP on these behaviors was reversed in F3 mice as compared with F1 mice. F1 mice exposed to low and medium DEHP doses spent more time in the closed arms of the elevated plus maze than controls, indicating increased anxiety-like behavior. The generation-dependent effects on behavior and AGI suggest complex mechanisms by which DEHP directly impacts reproductive and neurobehavioral development and influences germline-inherited traits. PMID:28199414

  13. 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.

  14. Restoration of Poissonian images using alternating direction optimization.

    PubMed

    Figueiredo, Mário A T; Bioucas-Dias, José M

    2010-12-01

    Much research has been devoted to the problem of restoring Poissonian images, namely for medical and astronomical applications. However, the restoration of these images using state-of-the-art regularizers (such as those based upon multiscale representations or total variation) is still an active research area, since the associated optimization problems are quite challenging. In this paper, we propose an approach to deconvolving Poissonian images, which is based upon an alternating direction optimization method. The standard regularization [or maximum a posteriori (MAP)] restoration criterion, which combines the Poisson log-likelihood with a (nonsmooth) convex regularizer (log-prior), leads to hard optimization problems: the log-likelihood is nonquadratic and nonseparable, the regularizer is nonsmooth, and there is a nonnegativity constraint. Using standard convex analysis tools, we present sufficient conditions for existence and uniqueness of solutions of these optimization problems, for several types of regularizers: total-variation, frame-based analysis, and frame-based synthesis. We attack these problems with an instance of the alternating direction method of multipliers (ADMM), which belongs to the family of augmented Lagrangian algorithms. We study sufficient conditions for convergence and show that these are satisfied, either under total-variation or frame-based (analysis and synthesis) regularization. The resulting algorithms are shown to outperform alternative state-of-the-art methods, both in terms of speed and restoration accuracy.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Magnetic particle imaging: current developments and future directions.

    PubMed

    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 future directions

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. Human genome sequencing with direct x-ray holographic imaging

    SciTech Connect

    Rhodes, C.K.

    1993-06-08

    Direct holographic imaging of biological materials is widely applicable to the study of the structure, properties and action of genetic material. This particular application involves the sequencing of the human genome where prospective genomic imaging technology is composed of three subtechnologies, name an x-ray holographic camera, suitable chemistry and enzymology for the preparation of tagged DNA samples, and the illuminator in the form of an x-ray laser. We report appropriate x-ray camera, embodied by the instrument developed by MCR, is available and that suitable chemical and enzymatic procedures exist for the preparation of the necessary tagged DNA strands. Concerning the future development of the x-ray illuminator. We find that a practical small scale x-ray light source is indeed feasible. This outcome requires the use of unconventional physical processes in order to achieve the necessary power-compression in the amplifying medium. The understanding of these new physical mechanisms is developing rapidly. Importantly, although the x-ray source does not currently exist, the understanding of these new physical mechanisms is developing rapidly and the research has established the basic scaling laws that will determine the properties of the x-ray illuminator. When this x-ray source becomes available, an extremely rapid and cost effective instrument for 3-D imaging of biological materials can be applied to a wide range of biological structural assays, including the base-pair sequencing of the human genome and many questions regarding its higher levels of organization.

  9. 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

  10. Analysis of High Contrast Imaging Techniques for Space Based Direct Planetary Imaging

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Gezari, Dan Y.; Nisenson, P.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We report on our ongoing investigations of a number of techniques for direct detection and imaging of Earth-like planets around nearby stellar sources. Herein, we give a quantitative analysis of these techniques and compare and contrast them via computer simulations. The techniques we will be reporting on are Bracewell Interferometry, Nisenson Apodized Square Aperture, and Coronagraphic masking techniques. We parameterize our results with respect to wavelength, aperture size, effects of mirror speckle, both mid- and high-spatial frequency, detector and photon noise as well pointing error. The recent numerous detections of Jupiter and Saturn like planets has driven a resurgence in research of space based high contrast imaging techniques for direct planetary imaging. Work is currently ongoing for concepts for NASA's Terrestrial Planet Finder mission and a number of study teams have been funded. The authors are members of one team.

  11. 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

  12. 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.

  13. Direct imaging with a hypertelescope of red supergiant stellar surfaces

    NASA Astrophysics Data System (ADS)

    Patru, F.; Chiavassa, A.; Mourard, D.; Tarmoul, N.

    2010-07-01

    High angular resolution images obtained with a hypertelescope can strongly constrain the radiative-hydrodynamics simulations of red supergiant (RSG) stars, in terms of intensity contrast, granulation size and temporal variations of the convective motions that are visible on their surface. The characterization of the convective pattern in RSGs is crucial to solve the mass-loss mechanism which contributes heavily to the chemical enrichment of the Galaxy. We show here how the astrophysical objectives and the array configuration are highly dependent to design a hypertelescope. For a given field of view and a given resolution, there is a trade-off between the array geometry and the number of required telescopes to optimize either the (u,v) coverage (to recover the intensity distribution) or the dynamic range (to recover the intensity contrast). To obtain direct snapshot images of Betelgeuse with a hypertelescope, a regular and uniform layout of telescopes is the best array configuration to recover the intensity contrast and the distribution of both large and small granulation cells, but it requires a huge number of telescopes (several hundreds or thousands). An annular configuration allows a reasonable number of telescopes (lower than one hundred) to recover the spatial structures but it provides a low-contrast image. Concerning the design of a pupil densifier to combine all the beams, the photometric fluctuations are not critical (Delta photometry < 50%) contrary to the residual piston requirements (OPD < λ/8) which requires the development of an efficient cophasing system to fully exploit the imaging capability of a hypertelecope.

  14. 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.

  15. Synthesis and cell imaging applications of fluorescent mono/di/tri-heterocyclyl-2,6-dicyanoanilines.

    PubMed

    Pisal, Mahesh M; Annadate, Ritesh A; Athalye, Meghana C; Kumar, Deepak; Chavan, Subhash P; Sarkar, Dhiman; Borate, Hanumant B

    2017-02-15

    Synthesis of 3,4,5-triheterocyclyl-2,6-dicyanoanilines, starting from heterocyclic aldehydes and 1,2-diheterocycle-substituted ethanones, is described. 2,6-Dicyanoanilines with one or two heterocyclic substituents have also been synthesized. It was found that some of these molecules have selective cell-staining properties useful for cell imaging applications. The compounds 1g, 10f and 11 were found to stain cytoplasm of the cells in contact but not the nucleus while the compound 12 showed affinity to apoptotic cells resulting in blue fluorescence. The cell imaging results with compound 12 were similar to Annexin V-FITC, a known reagent containing recombinant Annexin V conjugated to green-fluorescent FITC dye, used for detection of apoptotic cells. These compounds were found to be non-cytotoxic and have potential application as cell imaging agents.

  16. 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.

  17. 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.

  18. 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.

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

    PubMed

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

    2016-09-05

    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.

  20. 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.

  1. On the Composition of Young, Directly Imaged Giant Planets

    NASA Astrophysics Data System (ADS)

    Moses, J. I.; Marley, M. S.; Zahnle, K.; Line, M. R.; Fortney, J. J.; Barman, T. S.; Visscher, C.; Lewis, N. K.; Wolff, M. J.

    2016-10-01

    The past decade has seen significant progress on the direct detection and characterization of young, self-luminous giant planets at wide orbital separations from their host stars. Some of these planets show evidence for disequilibrium processes like transport-induced quenching in their atmospheres; photochemistry may also be important, despite the large orbital distances. These disequilibrium chemical processes can alter the expected composition, spectral behavior, thermal structure, and cooling history of the planets, and can potentially confuse determinations of bulk elemental ratios, which provide important insights into planet-formation mechanisms. Using a thermo/photochemical kinetics and transport model, we investigate the extent to which disequilibrium chemistry affects the composition and spectra of directly imaged giant exoplanets. Results for specific “young Jupiters” such as HR 8799 b and 51 Eri b are presented, as are general trends as a function of planetary effective temperature, surface gravity, incident ultraviolet flux, and strength of deep atmospheric convection. We find that quenching is very important on young Jupiters, leading to CO/CH4 and N2/NH3 ratios much greater than, and H2O mixing ratios a factor of a few less than, chemical-equilibrium predictions. Photochemistry can also be important on such planets, with CO2 and HCN being key photochemical products. Carbon dioxide becomes a major constituent when stratospheric temperatures are low and recycling of water via the {{{H}}}2 + OH reaction becomes kinetically stifled. Young Jupiters with effective temperatures ≲ 700 K are in a particularly interesting photochemical regime that differs from both transiting hot Jupiters and our own solar-system giant planets.

  2. 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.

  3. On the Composition of Young, Directly Imaged Giant Planets

    NASA Technical Reports Server (NTRS)

    Moses, J. I.; Marley, M. S.; Zahnle, K.; Line, M. R.; Fortney, J. J.; Barman, T. S.; Visscher, C.; Lewis, N. K.; Wolff, M. J.

    2016-01-01

    The past decade has seen significant progress on the direct detection and characterization of young, self-luminous giant planets at wide orbital separations from their host stars. Some of these planets show evidence for disequilibrium processes like transport-induced quenching in their atmospheres; photochemistry may also be important, despite the typically large orbital distances. Disequilibrium chemical processes such as these can alter the expected composition, spectral behavior, thermal structure, and cooling history of the planets, and can potentially confuse determinations of bulk elemental ratios, which provide important insights into planet-formation mechanisms. Using a thermo/photochemical kinetics and transport model, we investigate the extent to which disequilibrium chemical processes affect the composition and spectra of directly imaged giant exoplanets. Results for specific "young Jupiters" such as HR 8799 b and c and 51 Eri b are presented, as are general trends as a function of planetary effective temperature, surface gravity, incident ultraviolet flux, and strength of deep atmospheric convection. We find that quenching is very important on young Jupiters, leading to CO/CH4 and N2/NH3 ratios much greater than; and H2O mixing ratios a factor of a few less than chemical equilibrium predictions. Photochemistry can also be important on such planets, with CO2 and HCN being key photochemical products. Carbon dioxide becomes a particularly major constituent when stratospheric temperatures are low and recycling of water following H2O photolysis becomes stifled. Young Jupiters with effective temperatures less than 700 degrees Kelvin are in a particularly interesting photochemical regime that differs from both transiting hot Jupiters and our own solar-system giant planets.

  4. Direct selection of conserved cDNAs from the DiGeorge critical region: isolation of a novel CDC45-like gene.

    PubMed

    McKie, J M; Wadey, R B; Sutherland, H F; Taylor, C L; Scambler, P J

    1998-08-01

    We have used a modified direct selection technique to detect transcripts that are both evolutionary conserved and developmentally expressed. The enrichment for homologous mouse cDNAs by use of human genomic DNA as template is shown to be an efficient and rapid approach for generating transcript maps. Deletions of human 22q11 are associated with several clinical syndromes, with overlapping phenotypes, for example, velocardiofacial syndrome (VCFS) and DiGeorge syndrome (DGS). A large number of transcriptional units exist within the defined critical region, many of which have been identified previously by direct selection. However, no single obvious candidate gene for the VCFS/DGS phenotype has yet been found. Our technique has been applied to the DiGeorge critical region and has resulted in the isolation of a novel candidate gene, Cdc45l2, similar to yeast Cdc45p. [The sequence data described in this paper have been submitted to the EMBL data library under accession nos. AJ0223728 and AF0223729.

  5. Novel instrument concepts for characterizing directly imaged exoplanets

    NASA Astrophysics Data System (ADS)

    Keller, Christoph U.

    2016-08-01

    Current high-contrast exoplanet imagers are optimized to find new exoplanets; they minimize diffracted starlight in a large area around a star. I present four novel instrumental approaches that are optimized to characterize these discoveries by minimizing starlight in a small area around the known location of an exoplanet: 1) coronagraphs that remove virtually all starlight over an octave in wavelength while transmitting more than 90% of the exoplanet signal; 2) holographic wavefront sensors that measure aberrations in the science focal plane; 3) ultra-fast adaptive optics systems that minimize these aberrations; and 4) direct minimization of the remaining starlight. By integrating these technologies with a high spectral- resolution, integral-field spectrograph that can resolve the Doppler shift and the polarization difference between the starlight and the reflected light from the exoplanet, it will be possible to determine the atmospheric composition, temperature and velocity structures of exoplanets and their spin rotation rate and orbital velocity. This will ultimately allow the upcoming extremely large telescopes to characterize rocky exoplanets in the habitable zone to look for signatures of life.

  6. Hypertelescope architectures for direct imaging at high angular resolution

    NASA Astrophysics Data System (ADS)

    Labeyrie, Antoine; Arnold, Luc; Riaud, Pierre; Lardière, Olivier; Borkowski, Virginie; Gilet, Sohie; Dejonghe, Julien; Le Coroller, Hervé

    Optical arrays having many apertures, small compared to their spacings, can provide direct images with full luminosity if utilized according to the "densified pupil" or ``hypertelescope" scheme. On Earth, flat sites larger than 10km can be equipped with numerous mobile telescopes, or fixed telescopes with mobile beam combiners. Also of interest, although smaller, are instruments using a crater or other natural depression in a way similar to Arecibo's radio-telescope but with a diluted primary mirrror. These may be seen as "exploded" versions of machines such as the OWL. At equal collecting area, they provide the same limiting magnitude with 10 or 20 times improved angular resolution. A candidate design, called CARLINA, having the collecting area of the OWL is under study. Space versions of the latter type of architecture are also proposed to the space agencies for projects DARWIN and Terrestrial Planet Finder. Second-generation versions spanning several hundred kilometers, will in principle be capable of resolving details of Earth-like exo-planets.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Directly Imaging Planets with SCExAO: First Results

    NASA Astrophysics Data System (ADS)

    Currie, Thayne M.; Guyon, Olivier; Jovanovic, Nemanja; Lozi, Julien; Tamura, Motohide; Kudo, Tomoyuki; Uyama, Taichi; Garcia, Eugenio

    2017-01-01

    We present the first science results from the newly commissioned Subaru Coronagraphic Extreme Adaptive Optics project, an experimental system dedicated to image faint jovian planets around nearby stars. SCExAO is now achieving true extreme AO capability. We describe the typical performance of SCExAO, the first images of benchmark exoplanets and planet-forming disks, and SCExAO’s first science results. Finally, we briefly chart the path forward for SCExAO to achieve its full scientific capability, including imaging mature planets in reflected light.

  16. 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.

  17. RNA-based fluorescent biosensors for live cell imaging of second messengers cyclic di-GMP and cyclic AMP-GMP.

    PubMed

    Kellenberger, Colleen A; Wilson, Stephen C; Sales-Lee, Jade; Hammond, Ming C

    2013-04-03

    Cyclic dinucleotides are an important class of signaling molecules that regulate a wide variety of pathogenic responses in bacteria, but tools for monitoring their regulation in vivo are lacking. We have designed RNA-based fluorescent biosensors for cyclic di-GMP and cyclic AMP-GMP by fusing the Spinach aptamer to variants of a natural GEMM-I riboswitch. In live cell imaging experiments, these biosensors demonstrate fluorescence turn-on in response to cyclic dinucleotides, and they were used to confirm in vivo production of cyclic AMP-GMP by the enzyme DncV.

  18. Direct optical imaging of structural inhomogeneities in crystalline materials.

    PubMed

    Grigorev, A M

    2016-05-10

    A method for optical imaging of structural inhomogeneities in crystalline materials is proposed, based on the differences in the optical properties of the structural inhomogeneity and the homogeneous material near the fundamental absorption edge of the crystalline material. The method can be used to detect defects in both semiconductors and insulators.

  19. Cardiac MR imaging: current status and future direction.

    PubMed

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

    2015-08-01

    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

  20. 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.

  1. 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.

  2. 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

  3. Differential polarization direct imaging of FU Ori type YSO

    NASA Astrophysics Data System (ADS)

    Fu, Guangwei; Takami, Michihiro; Scicluna, Peter; Karr, Jennifer

    2017-01-01

    FU Orionis objects (FUors) are distinguished from other young stellar objects due to their outbursts. They can surge in brightness by multiple magnitudes in a short time. Thus FUors have always been considered the strongest evidence which suggests unsteady accretion process in low mass young stellar objects (YSO). However the accreting process of FUors are not well understood. We present high resolution (~0.1 arcseconds) observations of 5 FUors (FU Ori, V1057cyg, V1515cyg, V1735cyg, Z Cma) in near infrared bandpasses (J,H,K) using the Subaru telescope. Through using polarization differential imaging and coronagraphy techniques, we were able to obtain high contrast images of circumstellar environment around central young stars. After image processing, we found interesting structures (stream, tail, fragment, etc) in the circumstellar disks. These structures are indications for dynamical interaction, potential outflow cavities and disk fragmentation. More importantly, these disk features can provide us with insight into the accretion process and where outbursts originate.

  4. Hard-X-ray directional dark-field imaging using the speckle scanning technique.

    PubMed

    Wang, Hongchang; Kashyap, Yogesh; Sawhney, Kawal

    2015-03-13

    X-ray dark-field imaging can provide inaccessible and complementary information compared to conventional absorption contrast imaging. However, extraction of the dark-field signal is difficult, and sophisticated optics are often required. In this Letter, we report a novel approach to generate high-quality dark-field images using a simple membrane. The dark-field image is extracted from the maximum correlation coefficient by applying a cross-correlation algorithm to a stack of speckle images collected by scanning a membrane in a transverse direction to the incident x-ray beam. The new method can also provide directional dark-field information, which is extremely useful for the study of strongly ordered systems. The potential of the proposed technique for nondestructive x-ray imaging is demonstrated by imaging representative samples.

  5. 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.

  6. Direct observation of up-conversion via femtosecond photoelectron imaging

    NASA Astrophysics Data System (ADS)

    Liu, Yuzhu; Knopp, Gregor; Gerber, Thomas

    2015-10-01

    Ultrafast relaxation dynamics in 2-methylfuran has been investigated by time-resolved photoelectron imaging. An "up" internal conversion from a low-lying state into a higher-lying one has been observed experimentally. Temporal photoelectron kinetic-energy distributions and angular distributions of the photoelectrons are analyzed. In the up-conversion process, the vibrational energy in the initial state is converted to the electronic energy of the final state during the energy transfer. And the time scale for the up-conversion process is estimated by the observed onset delay for the corresponding photoelectron bands.

  7. 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.

  8. 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.

  9. 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.

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

    SciTech Connect

    Thakur, M.L.

    1994-05-03

    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. No Drawings

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. A line rate calculation method for arbitrary directional imaging of an Earth observing satellite

    NASA Astrophysics Data System (ADS)

    Jeon, Moon-Jin; Kim, Eunghyun; Lim, Seong-Bin; Choi, Seok-Weon

    2016-10-01

    For an earth observing satellite, a line rate is the number of lines which the CCD of push broom type camera scans in a second. It can be easily calculated by ground velocity divided by ground sample distance. Accurate calculation of line rate is necessary to obtain high quality image using TDI CCD. The earth observing satellite has four types of imaging missions which are strip imaging, stereo imaging, multi-point imaging, and arbitrary directional imaging. For the first three types of imaging, ground scanning direction is aligned with satellite velocity direction. Therefore, if the orbit propagation and spacecraft attitude information are available, the ground velocity and ground sample distance could be easily calculated. However, the calculation method might not be applicable to the arbitrary directional imaging. In the arbitrary directional imaging mode, the ground velocity is not fixed value which could be directly derived by orbit information. Furthermore, the ground sample distance might not be easily calculated by simple trigonometry which is possible for the other types of imaging. In this paper, we proposed a line rate calculation method for the arbitrary directional imaging. We applied spherical geometry to derive the equation of ground point which is the intersection between the line of sight vector of the camera and earth surface. The derivative of this equation for time is the ground velocity except the factor of earth rotation. By adding this equation and earth rotation factor, the true ground velocity vector could be derived. For the ground sample distance, we applied the equation of circle and ellipse for yaw angle difference. The equation of circle is used for the yaw angle representation on the plane which is orthogonal to the line of sight vector. The equation of ellipse is used for the yaw angle representation on the ground surface. We applied the proposed method to the KOMPSAT-3A (Korea Multi-Purpose Satellite 3A) mission which is the first

  17. Simulating a Radial Velocity Precurser Survey for Target Yield Optimization for a Future Direct Imaging Mission

    NASA Astrophysics Data System (ADS)

    Newman, Patrick; Plavchan, Peter; Crepp, Justin R.; Dulz, Shannon; Stark, Chris; Kane, Stephen R.

    2017-01-01

    Future direct imaging mission concepts such as HabEx and LUVOIR aim to directly image and characterize Earth-analogs around nearby stars. With the scope and expense of these missions, the exoplanet yield is strongly dependent on the frequency of Earth-like planets and the a priori knowledge of which stars specifically host suitable planetary systems. Ground-based radial velocity surveys can potentially perform the pre-selection of direct imaging missions at a fraction of the cost of a blind direct imaging survey. We present a simulation of such a survey. We consider both the WIYN and Large Binocular Telescope, including weather conditions and limitations in telescope time, fitted with spectrometers of varying sensitivities including iLocator and NEID. We recover simulated planets and their orbital parameters, estimating the effectiveness of a pre-cursor radial velocity survey.

  18. [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.

  19. Bi-directional two-dimensional/three-dimensional convertible integral imaging using scattering polarizer

    NASA Astrophysics Data System (ADS)

    Yeom, Jiwoon; Hong, Jisoo; Park, Soon-gi; Min, Sung-Wook; Lee, Byoungho

    2012-10-01

    A bi-directional 2D/3D convertible integral imaging system is proposed. Two optical modules composed of a scattering polarizer and a linear polarizer are adopted, and 2D or 3D mode operation is easily changed by converting polarization states of the projected images. In the 2D mode, the incident light is scattered at the scattering polarizer and the scattered light facing the lens-array is blocked, a 2D image is observable only at the same side as the projector. In the 3D mode, the incident light with the transmission polarization is directly projected onto a lens-array, and the 3D images are integrated. Our proposed system is able to display the 3D images as well as the 2D images for the observers who are placed in front and rear side of the system.

  20. Asymmetries in the direction of saccades during perception of scenes and fractals: effects of image type and image features.

    PubMed

    Foulsham, Tom; Kingstone, Alan

    2010-04-07

    The direction in which people tend to move their eyes when inspecting images can reveal the different influences on eye guidance in scene perception, and their time course. We investigated biases in saccade direction during a memory-encoding task with natural scenes and computer-generated fractals. Images were rotated to disentangle egocentric and image-based guidance. Saccades in fractals were more likely to be horizontal, regardless of orientation. In scenes, the first saccade often moved down and subsequent eye movements were predominantly vertical, relative to the scene. These biases were modulated by the distribution of visual features (saliency and clutter) in the scene. The results suggest that image orientation, visual features and the scene frame-of-reference have a rapid effect on eye guidance.

  1. 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.

  2. Direct imaging of isofrequency contours in photonic structures

    PubMed Central

    Regan, Emma C.; Igarashi, Yuichi; Zhen, Bo; Kaminer, Ido; Hsu, Chia Wei; Shen, Yichen; Joannopoulos, John D.; Soljačić, Marin

    2016-01-01

    The isofrequency contours of a photonic crystal are important for predicting and understanding exotic optical phenomena that are not apparent from high-symmetry band structure visualizations. We demonstrate a method to directly visualize the isofrequency contours of high-quality photonic crystal slabs that show quantitatively good agreement with numerical results throughout the visible spectrum. Our technique relies on resonance-enhanced photon scattering from generic fabrication disorder and surface roughness, so it can be applied to general photonic and plasmonic crystals or even quasi-crystals. We also present an analytical model of the scattering process, which explains the observation of isofrequency contours in our technique. Furthermore, the isofrequency contours provide information about the characteristics of the disorder and therefore serve as a feedback tool to improve fabrication processes. PMID:28138536

  3. 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.

  4. Direct exoplanet imaging with small-angle Vortex coronagraphs

    NASA Astrophysics Data System (ADS)

    Defrere, Denis; Absil, Olivier; Mawet, Dimitri; Michael, Karlsson; Habraken, Serge; Surdej, Jean; Absil, Pierre-Antoine; Carlomagno, Brunella; Christieans, Valentin; Delacroix, Christian; Girard, Julien; Forsberg, Pontus; Gonzalez Gomez, Carlos; Hinz, Phil; Huby, Elsa; Jolivet, Alyssa; Milli, Julien; Pantin, Eric; Piron, Pierre; Serabyn, Eugene; Van Droogenbroeck, Marc; Vargas Catalan, Ernesto; Wertz, Olivier

    2015-07-01

    Analysing the atmospheres of Earth and SuperEarth type planets for possible biomarkers will push us to the limits of current and future instrumentation. As the field matures, we must also upgrade our data analysis and interpretation techniques from their "ad-hoc" beginnings to a solid statistical foundation. This is particularly important for the optimal exploitation of future instruments, such as JWST and E-ELT. At the limits of low signal-to-noise, we are prone to two sources of biases: 1) Prior selection in the data reduction; 2) Prior constraints on the spectral retrieval. A unified set of tools addressing both points is required. To de-trend low S/N, correlated data, we demonstrated blind-source-separation (BSS) machine learning techniques to be a significant step forward. Both in photometry and spectroscopy. BSS finds applications in fields as diverse as medical imaging to cosmology. Applied to exoplanets, it allows us to resolve de-trending biases and demonstrate consistency between data sets that were previously found to be highly discrepant and subject to much debate. For the interpretation of the data, we developed a novel atmospheric retrieval suite, Tau-REx. Tau-REx implements an unbiased prior selections via a custom built pattern recognition software. A full subsequent mapping of the likelihood space (using cluster computing) allows us, for the first time, to fully study degeneracies and biases in emission and transmission spectroscopy. The development of a coherent end-to-end infrastructure is paramount to the characterisation of ever smaller and fainter foreign worlds. In this conference, I will discuss what we have learned for current observations and the need for unified statistical frameworks in the era of JWST, E-ELT.

  5. Image reconstruction for coherent imaging for space surveillance and directed energy applications

    NASA Astrophysics Data System (ADS)

    Holmes, Richard; Gudimetla, V. S. Rao

    2016-09-01

    Imaging of distant objects in a terrestrial environment involves propagation of light through significant turbulence. Conventional methods for imaging for these applications are radar or focal plane imaging. Both of these methods have limitations, such as object rotation rate and post-processing. A different class of imaging approaches involving coherent illumination has several advantages (a) reduced sensitivity to illumination conditions, (b) reduced sensitivity to object rotation, (c) the use of arrayed receivers that are lighter and lower in cost, and (d) snapshot reconstruction of aberrated images with just one or a few frames. These advantages must be balanced by the challenges of speckle noise in the image reconstructions, and more difficult algorithms. Coherent pupil-plane and focal-plane techniques are investigated for image formation. The associated algorithms include root-reconstruction techniques, phase smoothing methods, polynomial fit approaches, blind iterative deconvolution, and multi-frame blind deconvolution (MFBD). These techniques and algorithms are surveyed for speed and quality of image formation.

  6. Vortex Image Processing (VIP) package for high-contrast direct imaging

    NASA Astrophysics Data System (ADS)

    Gomez Gonzalez, C.; Absil, O.; Wertz, O.

    2016-05-01

    VIP is a Python instrument-agnostic toolbox featuring a flexible framework for reproducible and robust data reduction. VIP currently supports three high-contrast imaging observational techniques: angular, reference-star and multi-spectral differential imaging. The code can be downloaded from our git repository on Github: http://github.com/vortex-exoplanet/VIP

  7. Direct production of graphene nanosheets for near infrared photoacoustic imaging.

    PubMed

    Patel, Mehulkumar A; Yang, Hao; Chiu, Pui Lam; Mastrogiovanni, Daniel D T; Flach, Carol R; Savaram, Keerthi; Gomez, Lesly; Hemnarine, Ashley; Mendelsohn, Richard; Garfunkel, Eric; Jiang, Huabei; He, Huixin

    2013-09-24

    Hummers method is commonly used for the fabrication of graphene oxide (GO) from graphite particles. The oxidation process also leads to the cutting of graphene sheets into small pieces. From a thermodynamic perspective, it seems improbable that the aggressive, somewhat random oxidative cutting process could directly result in graphene nanosheets without destroying the intrinsic π-conjugated structures and the associated exotic properties of graphene. In Hummers method, both KMnO4 and NO2(+) (nitronium ions) in concentrated H2SO4 solutions act as oxidants via different oxidation mechanisms. From both experimental observations and theoretical calculations, it appears that KMnO4 plays a major role in the observed oxidative cutting and unzipping processes. We find that KMnO4 also limits nitronium oxidative etching of graphene basal planes, therefore slowing down graphene fracturing processes for nanosheet fabrication. By intentionally excluding KMnO4 and exploiting pure nitronium ion oxidation, aided by the unique thermal and kinetic effects induced by microwave heating, we find that graphite particles can be converted into graphene nanosheets with their π-conjugated aromatic structures and properties largely retained. Without the need of any postreduction processes to remove the high concentration of oxygenated groups that results from Hummers GO formation, the graphene nanosheets as-fabricated exhibit strong absorption, which is nearly wavelength-independent in the visible and near-infrared (NIR) regions, an optical property typical for intrinsic graphene sheets. For the first time, we demonstrate that strong photoacoustic signals can be generated from these graphene nanosheets with NIR excitation. The photo-to-acoustic conversion is weakly dependent on the wavelength of the NIR excitation, which is different from all other NIR photoacoustic contrast agents previously reported.

  8. Acceleration of the direct reconstruction of linear parametric images using nested algorithms.

    PubMed

    Wang, Guobao; Qi, Jinyi

    2010-03-07

    Parametric imaging using dynamic positron emission tomography (PET) provides important information for biological research and clinical diagnosis. Indirect and direct methods have been developed for reconstructing linear parametric images from dynamic PET data. Indirect methods are relatively simple and easy to implement because the image reconstruction and kinetic modeling are performed in two separate steps. Direct methods estimate parametric images directly from raw PET data and are statistically more efficient. However, the convergence rate of direct algorithms can be slow due to the coupling between the reconstruction and kinetic modeling. Here we present two fast gradient-type algorithms for direct reconstruction of linear parametric images. The new algorithms decouple the reconstruction and linear parametric modeling at each iteration by employing the principle of optimization transfer. Convergence speed is accelerated by running more sub-iterations of linear parametric estimation because the computation cost of the linear parametric modeling is much less than that of the image reconstruction. Computer simulation studies demonstrated that the new algorithms converge much faster than the traditional expectation maximization (EM) and the preconditioned conjugate gradient algorithms for dynamic PET.

  9. 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.

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

    DOE PAGES

    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

  11. Multispectral x-ray imaging for core temperature and density maps retrieval in direct drive implosions

    SciTech Connect

    Tommasini, Riccardo; Koch, Jeffrey A.; Izumi, Nobuhiko; Welser, Leslie A.; Mancini, Roberto C.; Delettrez, Jacques; Regan, Sean; Smalyuk, Vladimir

    2006-10-15

    We report on the experiments aimed at obtaining core temperature and density maps in direct drive implosions at the Omega laser facility using multimonochromatic x-ray imagers. These instruments use an array of pinholes and a flat multilayer mirror to provide unique multispectral images distributed over a wide spectral range. Using argon as a dopant in the direct-drive filled plastic shells produces emission images in the Ar He-{beta} and Ly-{beta} spectral regions. These images allow the retrieval of temperature and density maps of the plasma. We deployed three identical multimonochromatic x-ray imagers in a quasiorthogonal line-of-sight configuration to allow tomographic reconstruction of the structure of the imploding core.

  12. 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.

  13. Patient-directed Internet-based Medical Image Exchange: Experience from an Initial Multicenter Implementation

    PubMed Central

    Greco, Giampaolo; Patel, Anand S.; Lewis, Sara C.; Shi, Wei; Rasul, Rehana; Torosyan, Mary; Erickson, Bradley J.; Hiremath, Atheeth; Moskowitz, Alan J.; Tellis, Wyatt M.; Siegel, Eliot L.; Arenson, Ronald L.; Mendelson, David S.

    2015-01-01

    Rationale and Objectives Inefficient transfer of personal health records among providers negatively impacts quality of health care and increases cost. This multicenter study evaluates the implementation of the first Internet-based image-sharing system that gives patients ownership and control of their imaging exams, including assessment of patient satisfaction. Materials and Methods Patients receiving any medical imaging exams in four academic centers were eligible to have images uploaded into an online, Internet-based personal health record. Satisfaction surveys were provided during recruitment with questions on ease of use, privacy and security, and timeliness of access to images. Responses were rated on a five-point scale and compared using logistic regression and McNemar's test. Results A total of 2562 patients enrolled from July 2012 to August 2013. The median number of imaging exams uploaded per patient was 5. Most commonly, exams were plain X-rays (34.7%), computed tomography (25.7%), and magnetic resonance imaging (16.1%). Of 502 (19.6%) patient surveys returned, 448 indicated the method of image sharing (Internet, compact discs [CDs], both, other). Nearly all patients (96.5%) responded favorably to having direct access to images, and 78% reported viewing their medical images independently. There was no difference between Internet and CD users in satisfaction with privacy and security and timeliness of access to medical images. A greater percentage of Internet users compared to CD users reported access without difficulty (88.3% vs. 77.5%, P < 0.0001). Conclusion A patient-directed, interoperable, Internet-based image-sharing system is feasible and surpasses the use of CDs with respect to accessibility of imaging exams while generating similar satisfaction with respect to privacy. PMID:26625706

  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. Optical image compression based on adaptive directional prediction discrete wavelet transform

    NASA Astrophysics Data System (ADS)

    Zhang, Libao; Qiu, Bingchang

    2013-11-01

    The traditional lifting wavelet transform cannot effectively reconstruct the nonhorizontal and nonvertical high-frequency information of an image. In this paper, we present a new image compression method based on adaptive directional prediction discrete wavelet transform (ADP-DWT). We first design a directional prediction model to obtain the optimal transform direction of the lifting wavelet. Then, we execute the directional lifting transform along the optimal transform direction. The edge and texture energy can be reduced in the nonhorizontal and nonvertical directions of the high-frequency sub-bands. Finally, the wavelet coefficients are coded with the set partitioning in hierarchical trees (SPIHT) algorithm. The new method holds the advantages of both adaptive directional lifting (ADL) and direction-adaptive discrete wavelet transform (DA-DWT), and the computational complexity is far lower than that in these methods. For the images containing regular and fine textures or edges, the coding preformance of ADP-DWT is better than that of ADL and DA-DWT.

  16. A new type of remote sensors which allow directly forming certain statistical estimates of images

    NASA Astrophysics Data System (ADS)

    Podlaskin, Boris; Guk, Elena; Karpenko, Andrey

    2010-10-01

    A new approach to the problems of statistical and structural pattern recognition, a signal processing and image analysis techniques has been considered. These problems are extremely important for tasks being solved by airborne and space borne remote sensing systems. Development of new remote sensors for image and signal processing is inherently connected with a possibility of statistical processing of images. Fundamentally new optoelectronic sensors "Multiscan" have been suggested in the present paper. Such sensors make it possible to form directly certain statistical estimates, which describe completely enough the different types of images. The sensors under discussion perform the Lebesgue-Stieltjes signal integration rather than the Cauchy-Riemann one. That permits to create integral functionals for determining statistical features of images. The use of the integral functionals for image processing provides a good agreement of obtained statistical estimates with required image information features. The Multiscan remote sensors allows to create a set of integral moments of an input image right up to high-order integral moments, to form a quantile representation of an input image, which provides a count number limited texture, to form a median, which provides a localisation of a low-contrast horizon line in fog, localisation of water flow boundary etc. This work presents both the description of the design concept of the new remote sensor and mathematical apparatus providing the possibility to create input image statistical features and integral functionals.

  17. Direct imaging with highly diluted apertures - I. Field-of-view limitations

    NASA Astrophysics Data System (ADS)

    Lardière, O.; Martinache, F.; Patru, F.

    2007-03-01

    Future optical interferometric instrumentations mainly rely on the availability of an efficient cophasing system: once available, what has so far postponed the relevance of direct imaging to an interferometer will vanish. This paper focuses on the actual limits of snapshot imaging, inherent to the use of a sparse aperture: the number of telescopes and the geometry of the array impose the maximum extent of the field of view (FOV) and the complexity of the sources. A second limitation may arise from the beam combination scheme. Comparing already available solutions, we show that the so-called hypertelescope mode (or densified pupil) is ideal. By adjusting the direct imaging FOV to the useful FOV offered by the array, the hypertelescope makes an optimal use of the collected photons. It optimizes signal-to-noise ratio, drastically improves the luminosity of images and makes the interferometer compatible with coronagraphy, without inducing any loss of useful FOV.

  18. 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.

  19. Multiresolution image representation using combined 2-D and 1-D directional filter banks.

    PubMed

    Tanaka, Yuichi; Ikehara, Masaaki; Nguyen, Truong Q

    2009-02-01

    In this paper, effective multiresolution image representations using a combination of 2-D filter bank (FB) and directional wavelet transform (WT) are presented. The proposed methods yield simple implementation and low computation costs compared to previous 1-D and 2-D FB combinations or adaptive directional WT methods. Furthermore, they are nonredundant transforms and realize quad-tree like multiresolution representations. In applications on nonlinear approximation, image coding, and denoising, the proposed filter banks show visual quality improvements and have higher PSNR than the conventional separable WT or the contourlet.

  20. 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.

  1. 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.

  2. 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

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

    PubMed

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

    2015-05-22

    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.

  4. Adaptive optics confocal fluorescence microscopy with direct wavefront sensing for brain tissue imaging

    NASA Astrophysics Data System (ADS)

    Tao, Xiaodong; Fernandez, Bautista; Chen, Diana C.; Azucena, Oscar; Fu, Min; Zuo, Yi; Kubby, Joel

    2011-03-01

    Recently, there has been a growing interest in deep tissue imaging for the study of neurons. Unfortunately, because of the inhomogeneous refractive index of the tissue, the aberrations degrade the resolution and brightness of the final image. In this paper, we describe an adaptive optics confocal fluorescence microscope (AOCFM) which can correct aberrations based on direct wavefront measurements using a point source reference beacon and a Shack-Hartmann Wavefront Sensor (SHWS). Mouse brain tissues with different thicknesses are tested. After correction, both the signal intensity and contrast of the image are improved.

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

    PubMed Central

    Genkina, D; Aycock, LM; Stuhl, BK; Lu, H-I; Williams, RA; Spielman, IB

    2016-01-01

    We directly measured the normalized s-wave scattering cross-section of ultracold 40K 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 B0 = 20.206(15) mT with width Δ = 1.0(5) mT. To optimize the signal-to-noise ratio 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 signal-to-noise ratio on atom number counting at the expense of spatial imaging resolution. PMID:26903778

  6. 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.

  7. 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.

  8. Direct imaging with highly diluted apertures - II. Properties of the point spread function of a hypertelescope

    NASA Astrophysics Data System (ADS)

    Patru, F.; Tarmoul, N.; Mourard, D.; Lardière, O.

    2009-06-01

    In the future, optical stellar interferometers will provide true images thanks to larger number of telescopes and to advanced cophasing subsystems. These conditions are required to have sufficient resolution elements (resel) in the image and to provide direct images in the hypertelescope mode. It has already been shown that hypertelescopes provide snapshot images with a significant gain in sensitivity without inducing any loss of the useful field of view for direct imaging applications. This paper aims at studying the properties of the point spread functions of future large arrays using the hypertelescope mode. Numerical simulations have been performed and criteria have been defined to study the image properties. It is shown that the choice of the configuration of the array is a trade-off between the resolution, the halo level and the field of view. A regular pattern of the array of telescopes optimizes the image quality (low halo level and maximum encircled energy in the central peak), but decreases the useful field of view. Moreover, a non-redundant array is less sensitive to the space aliasing effect than a redundant array.

  9. Direct Imaging of Single Plasmonic Metal Nanoparticles in Capillary with Laser Light-Sheet Scattering Imaging.

    PubMed

    Cao, Xuan; Feng, Jingjing; Pan, Qi; Xiong, Bin; He, Yan; Yeung, Edward S

    2017-03-07

    Understanding the heterogeneous distribution of the physical and chemical properties of plasmonic metal nanoparticles is fundamentally important to their basic and applied research. Traditionally, they are obtained either indirectly via bulk spectroscopic measurements plus electron microscopic characterizations or through single molecule/particle imaging of nanoparticles immobilized on planar substrates. In this study, by using light-sheet scattering microscopy with a supercontinuum white laser, highly sensitive imaging of individual metal nanoparticles (MNPs) flowing inside a capillary, driven by either pressure or electric field, was achieved for the first time. We demonstrate that single plasmonic nanoparticles with different size or chemical modification could be differentiated through their electrophoretic mobility in a few minutes. This technique could potentially be applied to high throughput characterization and evaluation of single metal nanoparticles as well as their dynamic interactions with various local environments.

  10. 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.

  11. 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.

  12. 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.

  13. Effective Alternating Direction Optimization Methods for Sparsity-Constrained Blind Image Deblurring.

    PubMed

    Xiong, Naixue; Liu, Ryan Wen; Liang, Maohan; Wu, Di; Liu, Zhao; Wu, Huisi

    2017-01-18

    Single-image blind deblurring for imaging sensors in the Internet of Things (IoT) is a challenging ill-conditioned inverse problem, which requires regularization techniques to stabilize the image restoration process. The purpose is to recover the underlying blur kernel and latent sharp image from only one blurred image. Under many degraded imaging conditions, the blur kernel could be considered not only spatially sparse, but also piecewise smooth with the support of a continuous curve. By taking advantage of the hybrid sparse properties of the blur kernel, a hybrid regularization method is proposed in this paper to robustly and accurately estimate the blur kernel. The effectiveness of the proposed blur kernel estimation method is enhanced by incorporating both the L 1 -norm of kernel intensity and the squared L 2 -norm of the intensity derivative. Once the accurate estimation of the blur kernel is obtained, the original blind deblurring can be simplified to the direct deconvolution of blurred images. To guarantee robust non-blind deconvolution, a variational image restoration model is presented based on the L 1 -norm data-fidelity term and the total generalized variation (TGV) regularizer of second-order. All non-smooth optimization problems related to blur kernel estimation and non-blind deconvolution are effectively handled by using the alternating direction method of multipliers (ADMM)-based numerical methods. Comprehensive experiments on both synthetic and realistic datasets have been implemented to compare the proposed method with several state-of-the-art methods. The experimental comparisons have illustrated the satisfactory imaging performance of the proposed method in terms of quantitative and qualitative evaluations.

  14. Effective Alternating Direction Optimization Methods for Sparsity-Constrained Blind Image Deblurring

    PubMed Central

    Xiong, Naixue; Liu, Ryan Wen; Liang, Maohan; Wu, Di; Liu, Zhao; Wu, Huisi

    2017-01-01

    Single-image blind deblurring for imaging sensors in the Internet of Things (IoT) is a challenging ill-conditioned inverse problem, which requires regularization techniques to stabilize the image restoration process. The purpose is to recover the underlying blur kernel and latent sharp image from only one blurred image. Under many degraded imaging conditions, the blur kernel could be considered not only spatially sparse, but also piecewise smooth with the support of a continuous curve. By taking advantage of the hybrid sparse properties of the blur kernel, a hybrid regularization method is proposed in this paper to robustly and accurately estimate the blur kernel. The effectiveness of the proposed blur kernel estimation method is enhanced by incorporating both the L1-norm of kernel intensity and the squared L2-norm of the intensity derivative. Once the accurate estimation of the blur kernel is obtained, the original blind deblurring can be simplified to the direct deconvolution of blurred images. To guarantee robust non-blind deconvolution, a variational image restoration model is presented based on the L1-norm data-fidelity term and the total generalized variation (TGV) regularizer of second-order. All non-smooth optimization problems related to blur kernel estimation and non-blind deconvolution are effectively handled by using the alternating direction method of multipliers (ADMM)-based numerical methods. Comprehensive experiments on both synthetic and realistic datasets have been implemented to compare the proposed method with several state-of-the-art methods. The experimental comparisons have illustrated the satisfactory imaging performance of the proposed method in terms of quantitative and qualitative evaluations. PMID:28106764

  15. Model tags: direct three-dimensional tracking of heart wall motion from tagged magnetic resonance images.

    PubMed

    Young, A A

    1999-12-01

    Although magnetic resonance tissue tagging is a useful tool for the non-invasive measurement of three-dimensional (3-D) heart wall motion, the clinical utility of current analysis techniques is limited by the prohibitively long time required for image analysis. A method was therefore developed for the reconstruction of 3-D heart wall motion directly from tagged magnetic resonance images, without prior identification of ventricular boundaries or tag stripe locations. The method utilized a finite-element model to describe the shape and motion of the heart. Initially, the model geometry was determined at the time of tag creation by fitting a small number of guide points which were placed interactively on the images. Model tags were then created within the model as material surfaces which defined the location of the magnetic tags. An objective function was derived to measure the degree of match between the model tags and the image stripes. The objective was minimized by allowing the model to deform directly under the influence of the images, utilizing an efficient method for calculating image-derived motion constraints. The model deformation could also be manipulated interactively by guide points. Experiments were performed using clinical images of a normal volunteer, as well as simulated images in which the true motion was specified. The root-mean-squared errors between the known and calculated displacement and strain for the simulated images were similar to those obtained using previous stripe-tracking and model-fitting methods. A significant improvement in analysis time was obtained for the normal volunteer and further improvements may allow the method to be applied in a 'real-time' clinical environment.

  16. 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/.

  17. Direct imaging of optimal photonic nanojets from core-shell microcylinders.

    PubMed

    Liu, Cheng-Yang; Hsiao, Kai-Lung

    2015-11-15

    We first experimentally evaluate the direct imaging of photonic nanojets from core-shell microcylinders. The optimal photonic nanojet with long length, a high intensity spot, and low divergence is observed at the designed gold-silver-coating microcylinder. A special microcylinder consists of multilayered metallic shells (gold, silver, and copper) and a dielectric core (polydimethylsiloxane) at a diameter of 5 μm and a height of 6 μm. The electromagnetic distributions inside and outside the core-shell microcylinders are calculated by using the finite-difference time-domain method. The direct-imaging measurements for photonic nanojets are performed with a scanning-optical-microscope system. Such core-shell microcylinders provide new pathways for high-resolution optical imaging, which are useful for biophotonics, plasmonics, and optical data storage.

  18. 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.

  19. Design and implementation of magnetically maneuverable capsule endoscope system with direction reference for image navigation.

    PubMed

    Sun, Zhen-Jun; Ye, Bo; Sun, Yi; Zhang, Hong-Hai; Liu, Sheng

    2014-07-01

    This article describes a novel magnetically maneuverable capsule endoscope system with direction reference for image navigation. This direction reference was employed by utilizing a specific magnet configuration between a pair of external permanent magnets and a magnetic shell coated on the external capsule endoscope surface. A pair of customized Cartesian robots, each with only 4 degrees of freedom, was built to hold the external permanent magnets as their end-effectors. These robots, together with their external permanent magnets, were placed on two opposite sides of a "patient bed." Because of the optimized configuration based on magnetic analysis between the external permanent magnets and the magnetic shell, a simplified control strategy was proposed, and only two parameters, yaw step angle and moving step, were necessary for the employed robotic system. Step-by-step experiments demonstrated that the proposed system is capable of magnetically maneuvering the capsule endoscope while providing direction reference for image navigation.

  20. 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.

  1. The impact of space-time speckle to the resolution in range and azimuth direction on synthetic aperture imaging ladar

    NASA Astrophysics Data System (ADS)

    Xu, Qian; Zhou, Yu; Sun, Jianfeng; Zhi, Ya'nan; Ma, Xiaoping; Sun, Zhiwei; Lu, Dong; Liu, Liren

    2013-09-01

    As synthetic aperture imaging ladar employs the linear chirp laser signal, it is inevitably impacted by the space-time varying speckle effect. In many SAIL two-dimensional reconstructed images, the laser speckle effect severely reduces the image quality. In this paper, we analyze and simulate the influence of space-time speckle effect to the resolution element imaging both in range direction and in azimuth direction. Expressions for two-dimensional data collection contained space-time speckle effect are obtained, and computer simulation results of resolution degradation both in range direction and in cross-range direction are presented.

  2. 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

  3. 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

  4. Improvement of spatial resolution in the longitudinal direction for isotropic imaging in helical CT

    NASA Astrophysics Data System (ADS)

    Tsukagoshi, Shinsuke; Ota, Takamasa; Fujii, Misako; Kazama, Masahiro; Okumura, Miwa; Johkoh, Takeshi

    2007-02-01

    Experiments were conducted to confirm the isotropic spatial resolution of multislice CT with a 0.5 mm slice thickness. Isotropic spatial resolution means that the spatial resolution in the transaxial plane (X-Y plane) and that in the longitudinal direction (Z direction) are equivalent. To obtain point spread function (PSF) values in the X-Y-Z directions, three-dimensional voxel data were obtained by helical scanning of a bead phantom. The modulation transfer function (MTF) values were then obtained by three-dimensional Fourier transform of the PSF. Evaluation of the spatial resolution in the X-Y-Z directions by the MTF values showed that the spatial resolution in the Z direction does not depend on the reconstruction kernel used. It was also found that the spatial resolution in the Z direction, as compared with that in the X-Y plane, is superior with the standard kernel for the abdomen and is inferior with the high-definition kernel for the ears/bones. By performing sharpening filter processing in the Z direction with a high-definition kernel, comparable spatial resolution could be obtained in the X-Y-Z directions. It was confirmed that adjusting the spatial resolution in the Z direction with the reconstruction kernel used is an effective method for isotropic imaging.

  5. Direct-conversion flat-panel x-ray imaging: reduction of noise by presampling filtration

    NASA Astrophysics Data System (ADS)

    Rowlands, John A.; Ji, Winston G.; Zhao, Wei; Lee, Denny L. Y.

    2000-04-01

    Large area flat panel solid-state detectors are being studied for digital radiography and fluoroscopy. Such systems use active matrix arrays to readout latent charge images created either by direct conversion of x-ray energy to charge in a photoconductor or indirectly using a phosphor and individual photodiodes on the active matrix array. Our work has utilized the direct conversion method because of its simplicity and the higher resolution possible due to the electrostatic collection of secondary quanta. Aliasing of noise occurs in current designs of direct detectors based on amorphous selenium ((alpha) -Se) because of its high intrinsic resolution. This aliasing leads to a decrease in detective quantum efficiency (DQE) as frequency increases. It has been predicted, using a previously developed model of the complete imaging system, that appropriately controlled spatial filtration can reduce this aliased noise and hence increase DQE at the Nyquist frequency, fNY. Our purpose is to experimentally verify this concept by implementing presampling filtration in a practical flat panel system. An (alpha) -Se based flat panel imager is modified by incorporating an insulating layer between the active matrix and the (alpha) -Se layer to introduce a predetermined amount of presampling burring. The modified imager is evaluated using standard linear analysis tools, modulation transfer function (MTF), noise power spectra (NPS) and DQE(f), and the results are compared to theoretical predictions.

  6. Laser direct imaging of high density patterns on PCB covered by photoresist

    NASA Astrophysics Data System (ADS)

    Barbucha, R.; Kocik, M.; Mizeraczyk, J.; Koziol, G.; Borecki, J.

    2007-03-01

    The increasing demands for miniaturization and better functionality of electronic components and devices have a significant effect on the requirements facing the printed circuit board (PCB) industry. PCB manufactures are driving for producing high density interconnect (HDI) boards at significantly reduced cost and reduced implementation time. The interconnection complexity of the PCB is still growing and today calls for 50/50 μm or 25/25 μm technology are real. Existing technologies are unable to offer acceptable solution. Recently the Laser Direct Imaging (LDI) technology is considered as an answer for these challenges. LDI is a process of imaging electric circuits directly on PCB without the use of a phototool or mask. The exposure of the photo-sensitive resist is carried out using a laser beam that is scanned across photoresist surface and switched on and off by means of a computer control system according to the electrical circuit pattern. Usually the laser used in the LDI generates a UV line, which is suitable to the commonly available photoresists. In this paper we present the laboratory system for Laser Direct Imaging and also the recent results on imaging the circuitry pattern on the PCB covered by a photosensitive resist.

  7. 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.

  8. Space Telescope Design to Directly Image the Habitable Zone of Alpha Centauri

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

    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&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 10(exp 10) 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 high precision 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 approximately 2e-11 levels, enabling high confidence and at least 90% completeness detections of Earth-like planets.

  9. 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.

  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.

  11. Ambienti Circumstellari ed Interstellari di Supernovae di vario Tipo ed Applicazioni Astrofisiche

    NASA Astrophysics Data System (ADS)

    Boffi, Francesca R.

    extra-galattiche per via puramente geometrica (Sparks 1994; 1996). Osservazioni da terra, in imaging e polarimetria, sono state utilizzate per selezionare un numero promettente di candidati, che mostrano emissione visibile alla posizione della supernova. Tali candidati sono promettenti non solo per l' applicazione del metodo descritto ma anche per dedurre informazioni circa le supernovae medesime e le relative popolazioni stellari.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. Direct x-ray sensing CCD array for intraoral dental x-ray imaging system

    NASA Astrophysics Data System (ADS)

    Cox, John D.; Williams, Donald W.; Langford, D. S.

    1994-05-01

    A commercial prototype electronic intraoral dental x-ray imaging system employing a direct sensing CCD array has been developed. Image quality parameters were measured using x-ray sources at the National Institute of Standard and Technology radiation physical department in Gaithersburg, MD. Detector response to x-rays in the 10 to 70 keV energy range was measured. The beam hardening effects of human anatomy on a typical 70 kVp spectra was measured using a tissue-equivalent dental phantom.

  18. Direct imaging in interferometry: technical aspects and preliminary results of a fibered pupil densifier

    NASA Astrophysics Data System (ADS)

    Patru, Fabien; Mourard, Denis; Delage, Laurent; Reynaud, François; Clausse, Jean-Michel; Bonneau, Daniel; Dubreuil, Michael; Roussel, Alain; Hugues, Yves; Bosio, Sandra; Bresson, Yves; Lardière, Olivier

    2006-06-01

    We present a test bench designed to study the performances of interferometric recombination systems, mainly for direct imaging applications (hypertelescope principle). It aims at comparing the aperture synthesis, Fizeau and densified pupils beam combination schemes. It allows identification of the technical requirements like photometry and cophasing correction of the future imaging recombiners for large arrays. A densified assembly has been designed in the visible wavelengths, using a multi-apertures mask associated with a wavefront sensor. It allows pupil rearrangement and spatial filtering by using single mode fibers. The technical specifications and the conception of the fiber densifier are described here, with a particular attention to the correction of the differential chromatic dispersion.

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

    PubMed

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

    2012-08-01

    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.

  20. 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.

  1. 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.

  2. Markov random field models for directional field and singularity extraction in fingerprint images.

    PubMed

    Dass, Sarat C

    2004-10-01

    A Bayesian formulation is proposed for reliable and robust extraction of the directional field in fingerprint images using a class of spatially smooth priors. The spatial smoothness allows for robust directional field estimation in the presence of moderate noise levels. Parametric template models are suggested as candidate singularity models for singularity detection. The parametric models enable joint extraction of the directional field and the singularities in fingerprint impressions by dynamic updating of feature information. This allows for the detection of singularities that may have previously been missed, as well as better aligning the directional field around detected singularities. A criteria is presented for selecting an optimal block size to reduce the number of spurious singularity detections. The best rates of spurious detection and missed singularities given by the algorithm are 4.9% and 7.1%, respectively, based on the NIST 4 database.

  3. Characterization and optimization of a thin direct electron detector for fast imaging applications

    NASA Astrophysics Data System (ADS)

    Dourki, I.; Westermeier, F.; Schopper, F.; Richter, R. H.; Andricek, L.; Ninkovic, J.; Treis, J.; Koffmane, C.; Wassatsch, A.; Peric, I.; Epp, S. W.; Miller, R. J. D.

    2017-03-01

    Direct electron detectors are increasingly used to explore the dynamics of macromolecules in real space and real time using transmission electron microscopy. The purpose of this work is to optimize the most suitable detector configuration of a thin silicon detector by Monte Carlo Simulations. Several simulations were performed to achieve an advanced detector geometry that reduces significantly the background signal due to backscattered electrons resulting in an enhanced imaging performance of the detector. Utilizing DEPFET (DEpleted P-channel Field Effect Transistor) technology and the novel ideas for the optimized detector geometry, a unique direct hit electron detector is currently being produced.

  4. Image-Guided Hydrodynamic Gene Delivery: Current Status and Future Directions

    PubMed Central

    Kamimura, Kenya; Yokoo, Takeshi; Abe, Hiroyuki; Kobayashi, Yuji; Ogawa, Kohei; Shinagawa, Yoko; Inoue, Ryosuke; Terai, Shuji

    2015-01-01

    Hydrodynamics-based delivery has been used as an experimental tool to express transgene in small animals. This in vivo gene transfer method is useful for functional analysis of genetic elements, therapeutic effect of oligonucleotides, and cancer cells to establish the metastatic cancer animal model for experimental research. Recent progress in the development of image-guided procedure for hydrodynamics-based gene delivery in large animals directly supports the clinical applicability of this technique. This review summarizes the current status and recent progress in the development of hydrodynamics-based gene delivery and discusses the future directions for its clinical application. PMID:26308044

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. Direct injection of indicators for calcium imaging at the Drosophila larval neuromuscular junction.

    PubMed

    Macleod, Gregory T

    2012-07-01

    Calcium imaging is a technique in which Ca(2+)-binding molecules are loaded into live cells and as they bind Ca(2+) they "indicate" the concentration of free calcium through a change in either the intensity or the wavelength of light emitted (fluorescence or bioluminescence). There are several possible methods for loading synthetic Ca(2+) indicators into subcellular compartments, including topical application of membrane-permeant Ca(2+) indicators, forward-filling of dextran conjugates, and direct injection. Calcium imaging is a highly informative technique in neurobiology because Ca(2+) is involved in many neuronal signaling pathways and serves as the trigger for neurotransmitter release. This article describes the direct injection of Ca(2+) indicators at the Drosophila larval neuromuscular junction (NMJ). This technique allows rapid loading of most Ca(2+) indicators, but there are drawbacks in that it is a difficult technique to master and requires additional electrophysiological equipment. Also, Ca(2+) indicators that are easily injected are usually susceptible to compartmentalization.

  10. 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.

  11. 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.

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

    PubMed

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

    2016-06-17

    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.

  13. 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

  14. Ultrasonic Imaging and Theoretical Prediction of Orthotropic Plate Stiffness in all Planar Directions

    SciTech Connect

    Telschow, Kenneth Louis; Deason, Vance Albert; Mukdadi, O.; Datta, S. K.

    2000-07-01

    Exact and approximate theoretical analysis of the wavelengths of plate wave mode propagation in all planar directions for the dispersive antisymmetric Lamb wave mode are compared with measurements from a laser ultrasonic imaging approach that records the out of plane ultrasonic motion over a large area in a single frame without scanning. Good agreement is demonstrated, based on independent determination of the elastic constants, for two different types of paper.

  15. 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.

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

    PubMed

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

    2014-06-21

    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.

  17. Sub-Surface Microwave Imaging Using Four-Slot Vivaldi Antenna with Improved Directivity

    NASA Astrophysics Data System (ADS)

    Akhter, Zubair; Kumar, Pankaj; Akhtar, M. Jaleel

    2017-01-01

    The conventional tapered slot Vivaldi antenna is well known for its ultra-wide band characteristics with low directivity. To improve the directivity of the conventional Vivaldi antenna, a four-slot Vivaldi antenna (FSVA) is proposed here to operate in the frequency range of 2-11 GHz. For feeding the FSVA, a binomial three-section V-shaped even mode power divider with progressing T-junctions is also designed and tested here, which is then integrated with the antenna. The proposed antenna prototype is designed and fabricated on a 1-mm thick FR-4 substrate (ɛr=4.3, tanδ=0.025), and the return loss and radiation characteristics are investigated in the anechoic environment. The measured result shows a good agreement with the numerical simulation performed using the EM Simulator i. e. CST MWS-2015. It is found that the directivity of FSVA is approximately doubled as compared to that of the conventional Vivaldi antenna having the same dimensions. From the application point of view, the fabricated antenna is used to image various metallic objects hidden inside the sand using a vector network analyzer and associated RF components. The obtained 2D microwave images of the test media successfully show that the hidden objects can effectively be located and detected using the proposed FSVA in conjunction with a simple imaging scheme.

  18. Low end interactive image-directed neurosurgery. Update on rudimentary augmented reality used in epilepsy surgery.

    PubMed

    Doyle, W K

    1996-01-01

    Our experience with a very low end interactive image-directed (IIDS) neurosurgical system is presented. The system was developed by the author and consists of a personal desktop computer and a magnetic field digitizer. This low cost solution was pursued as an alternative to available commercial devices which were expensive and not readily modifiable for novel ideas and new applications targeted for Epilepsy surgery. The rationale and description of the system was presented last year at Medicine Meets Virtual Reality III. Included in that detailed report were the fundamental mathematics forming the basics of transformation between the surgical and the digital data spaces. Since then the system has been used in an additional 20 cases now totaling 40 in all. Its advantages and short comings will be described. The theoretical advantages of magnetic field technology over other localization methods is reviewed. Also, our experience with alternative low cost off-the-shelf interfacing devices and other related modifications are described. We have accumulated clinical data to suggest that craniotomy sizes have been reduced, electrode placement has been improved, and that interactive image-directed techniques offer advantages over other common intra-operative localization modalities such as ultrasound. Our conclusion is that interactive image-directed techniques improve neurosurgery and that inexpensive enabling technology is already available providing the technological substrate for low cost devices using virtual reality notions for surgery and medicine. This particular technology offers advantages to traditional surgical techniques demonstrating the attractiveness of rudimentary virtual reality medical applications.

  19. Retrieving direct and diffuse radiation with the use of sky imager pictures

    NASA Astrophysics Data System (ADS)

    Schmidt, Thomas; Kalisch, John; Lorenz, Elke

    2015-04-01

    A machine-learning approach for retrieving direct and diffuse irradiance from pictures taken by a ground-based whole-sky imagery (sky imager) is investigated in the present work. The use of sky imagers for shortest-term local solar irradiance forecasts is a growing field in research and industry. Accurate predictions of surface solar irradiance fluctuations up to 30 minutes ahead are important for a variety of solar energy and power grid applications. Sky imager picture analyses provide very high resolution binary cloud masks, but have limitations in deriving aerosol and cloud optical properties. In a first approach, surface solar irradiance was retrieved from the binary cloud masks with the use of clear sky and overcast irradiance calculations. With this method, forecast performance improvements over persistence could be achieved especially for broken cloud situations. These situations are characterized by inhomogeneous cloud patterns contributing to surface solar irradiance deviating from the clear sky or overcast levels. The accurate estimation of the radiative components will therefore improve the irradiance retrievals. One year of measurements at the University of Oldenburg was used as a robust data basis for this new approach. The data sets consists of direct, diffuse and global horizontal irradiance measured with a sample rate of 1 Hz. In order to account for diurnal and seasonal variations radiation measurements are normalized to the clear-sky conditions. Hemispheric images were taken every 10 s by a sky imager mounted close to the radiometers. The proposed approach uses image features like the average pixel intensity of the whole image and the circumsolar area, analyses of the gray-level co-occurence matrix (GLCM), information of the RGB and HSV color space and the analysed cloud fraction. In order to estimate normalized direct and diffuse radiation, a k-nearest neighbor (k-NN) regression algorithm is applied. The performance of this model is evaluated by

  20. [Image quality and detection performance of a direct digital radiography system].

    PubMed

    Ideguchi, Tadamitsu; Matsuda, Katsuhiko; Himuro, Kazuhiko; Kuwahara, Rie; Miyazaki, Hidetsune; Hazeyama, Hiroyuki; Kumazawa, Seiji; Kawaji, Yasuyuki; Yoshida, Akira; Matsumoto, Masao; Higashida, Yoshiharu

    2006-03-20

    The physical characteristics of a direct amorphous Selenium (a-Se) digital fluoroscopy and radiography system were investigated. Pre-sampled modulation transfer functions (MTF) were measured using a slit method. Noise power spectra were determined for different input exposures by fast Fourier transform of uniformly exposed samples. The MTFs of direct digital radiography systems showed significantly higher values than those of indirect digital radiography and screen-film systems. The direct digital radiography systems showed higher noise levels compared with those of indirect systems under roughly the same exposure conditions. Contrast-detail analysis was performed to compare detection by direct digital radiography systems with that of the screen-film (FUJI HG-M2/UR2) systems. The average contrast-detail curves of digital and film images were obtained from the results of observation. Image quality figures (IQF) were also calculated from the individual observer performance tests. The results indicated that digital contrast-detail curves and IQF are, on average, are equal those of the screen-film system.

  1. Contrast and resolution in direct Fresnel diffraction phase-contrast imaging with partially coherent x-ray source

    SciTech Connect

    Han Shensheng; Yu Hong; Cheng Jing; Gao Chen; Luo Zhenlin

    2004-10-01

    A general treatment of x-ray image formation by direct Fresnel diffraction with partially coherent hard x rays is presented. Contrast and resolution are the criteria used to specify the visibility of an image, which depend primarily on the spatial coherence of the illumination and the distance from object to the image, with chromatic coherence of lesser importance. The dependence of the quality of phase-contrast images on the parameters of in-line imaging configuration is described quantitatively. The influence of spatial coherence of hard x-ray source on the imaging quality is also discussed based on the partially coherent direct Fresnel diffraction phase-contrast imaging theory. Experimental results are also presented for phase-contrast x-ray images with partially coherent hard x rays.

  2. Why Alpha Centauri is a Particularly Good Target for Direct Imaging of Exoplanets.

    NASA Astrophysics Data System (ADS)

    Belikov, R.; Bendek, E.; Thomas, S.; Males, J.

    2015-12-01

    Several mission concepts are being studied to directly image planets around nearby stars. It is commonly thought that directly imaging a potentially habitable exoplanet around a Sun-like star requires space telescopes with apertures of at least 1m. A notable exception to this is Alpha Centauri (A and B), which is an extreme outlier among FGKM stars in terms of apparent habitable zone size: the habitable zones are ~3x wider in apparent size than around any other FGKM star and are thus in theory accessible to much smaller telescopes. Alpha Centauri is also an extreme outlier in terms of how bright its planets are. For example, an Earth-like planet would be several magnitudes brighter around Alpha Centauri than around any other Sun-like star. Alpha Centauri lies in the galactic plane but its high brightness and proper motion make confusion with background stars unlikely, and extinction by our own galaxy makes confusion with extragalactic sources unlikely. The high brightness also helps any planet stand out against exozodiacal light. Alpha Centauri B has a (probable) planet, which establishes that a planetary system has formed in the system despite the multiplicity of the system. Dynamical simulations show that the habitable zones around both Alpha Centauri A and B are stable, and RV measurements rule out any large planets in the system that may have disrupted the formation of habitable planets. Recently developed high contrast techniques enable the detection of planets in multi-star systems, enabling imaging planets around Alpha Centauri. In particular, a small ~30-45cm visible light space telescope equipped with a modern high performance coronagraph or starshade is sufficient to directly image any potentially habitable planet that may exist in the system.

  3. Analysis of image versus position, scale and direction reveals pattern texture anisotropy

    NASA Astrophysics Data System (ADS)

    Lehoucq, Roland; Weiss, Jerome; Dubrulle, Berengere; Amon, Axelle; Le Bouil, Antoine; Crassous, Jerome; Amitrano, David; Graner, Francois

    2014-12-01

    Pattern heterogeneities and anisotropies often carry significant physical information. We provide a toolbox which: (i) cumulates analysis in terms of position, direction and scale; (ii) is as general as possible; (iii) is simple and fast to understand, implement, execute and exploit. It consists in dividing the image into analysis boxes at a chosen scale; in each box an ellipse (the inertia tensor) is fitted to the signal and thus determines the direction in which the signal is more present. This tensor can be averaged in position and/or be used to study the dependence with scale. This choice is formally linked with Leray transforms and anisotropic wavelet analysis. Such protocol is intutively interpreted and consistent with what the eye detects: relevant scales, local variations in space, priviledged directions. It is fast and parallelizable. Its several variants are adaptable to the user's data and needs. It is useful to statistically characterize anisotropies of 2D or 3D patterns in which individual objects are not easily distinguished, with only minimal pre-processing of the raw image, and more generally applies to data in higher dimensions. It is less sensitive to edge effects, and thus better adapted for a multiscale analysis down to small scale boxes, than pair correlation function or Fourier transform. Easy to understand and implement, it complements more sophisticated methods such as Hough transform or diffusion tensor imaging. We use it on various fracture patterns (sea ice cover, thin sections of granite, granular materials), to pinpoint the maximal anisotropy scales. The results are robust to noise and to user choices. This toolbox could turn also useful for granular materials, hard condensed matter, geophysics, thin films, statistical mechanics, characterisation of networks, fluctuating amorphous systems, inhomogeneous and disordered systems, or medical imaging, among others.

  4. Using direct imaging to investigate the formation and migration histories of gas giant exoplanets

    NASA Astrophysics Data System (ADS)

    Ngo, Henry

    2016-10-01

    Gas giant exoplanets are found around their host stars at orbital separations spanning more than four orders of magnitude (0.01 to 100 AU). However, it is not known whether the planets at the extreme ends of this range could have formed in situ or if they instead formed closer to ice lines between 1-10 AU and then migrated to their present day locations. In this study, we use two direct imaging surveys to explore the potential origins of hot Jupiters and to characterize the population of gas giant planets beyond the ice line. In our first survey, we focus on the role of stellar companions in hot Jupiter formation and migration. We determine that less than 20% of hot Jupiters have stellar companions capable of inducing migration via Kozai-Lidov oscillations. In addition, we find that hot Jupiter hosts are three times more likely to have a stellar companion between 50-2000 AU than field stars, suggesting that binary star systems may be favorable environments for gas giant planet formation. In our second study, we present the results from the first year of a two-year direct imaging planet survey of 200 young M-dwarf stars. By imaging in L-band (3.8 micron) and taking advantage of the new 80 milliarcsecond inner working angle "vortex" coronagraph on Keck NIRC2, we are sensitive to young planets with masses between 1-10 Jupiter masses with projected separations between 1-10 AU. We can compare the semi-major axis distribution of directly imaged planets beyond 10 AU to that of intermediate period gas giants from radial velocity surveys and determine whether or not these two populations form a continuous distribution. If so, this would imply these populations share common formation (core accretion) and migration channels.

  5. Using direct imaging to investigate the formation and migration histories of gas giant exoplanets

    NASA Astrophysics Data System (ADS)

    Ngo, Henry

    2017-01-01

    Gas giant exoplanets are found around their host stars at orbital separations spanning more than four orders of magnitude (0.01 to 100 AU). However, it is not known whether the planets at the extreme ends of this range could have formed in situ or if they instead formed closer to ice lines between 1-10 AU and then migrated to their present day locations. In this study, we use two direct imaging surveys to explore the potential origins of hot Jupiters and to characterize the population of gas giant planets beyond the ice line. In our first survey, we focus on the role of stellar companions in hot Jupiter formation and migration. We determine that less than 20% of hot Jupiters have stellar companions capable of inducing migration via Kozai-Lidov oscillations. In addition, we find that hot Jupiter hosts are three times more likely to have a stellar companion between 50-2000 AU than field stars, suggesting that binary star systems may be favorable environments for gas giant planet formation. In our second study, we present the results from the first year of a two-year direct imaging planet survey of 200 young M-dwarf stars. By imaging in L-band (3.8 micron) and taking advantage of the new 80 milliarcsecond inner working angle "vortex" coronagraph on Keck NIRC2, we are sensitive to young planets with masses between 1-10 Jupiter masses with projected separations between 1-10 AU. We can compare the semi-major axis distribution of directly imaged planets beyond 10 AU to that of intermediate period gas giants from radial velocity surveys and determine whether or not these two populations form a continuous distribution. If so, this would imply these populations share common formation (core accretion) and migration channels.

  6. WE-AB-303-08: Direct Lung Tumor Tracking Using Short Imaging Arcs

    SciTech Connect

    Shieh, C; Huang, C; Keall, P; Feain, I

    2015-06-15

    Purpose: Most current tumor tracking technologies rely on implanted markers, which suffer from potential toxicity of marker placement and mis-targeting due to marker migration. Several markerless tracking methods have been proposed: these are either indirect methods or have difficulties tracking lung tumors in most clinical cases due to overlapping anatomies in 2D projection images. We propose a direct lung tumor tracking algorithm robust to overlapping anatomies using short imaging arcs. Methods: The proposed algorithm tracks the tumor based on kV projections acquired within the latest six-degree imaging arc. To account for respiratory motion, an external motion surrogate is used to select projections of the same phase within the latest arc. For each arc, the pre-treatment 4D cone-beam CT (CBCT) with tumor contours are used to estimate and remove the contribution to the integral attenuation from surrounding anatomies. The position of the tumor model extracted from 4D CBCT of the same phase is then optimized to match the processed projections using the conjugate gradient method. The algorithm was retrospectively validated on two kV scans of a lung cancer patient with implanted fiducial markers. This patient was selected as the tumor is attached to the mediastinum, representing a challenging case for markerless tracking methods. The tracking results were converted to expected marker positions and compared with marker trajectories obtained via direct marker segmentation (ground truth). Results: The root-mean-squared-errors of tracking were 0.8 mm and 0.9 mm in the superior-inferior direction for the two scans. Tracking error was found to be below 2 and 3 mm for 90% and 98% of the time, respectively. Conclusions: A direct lung tumor tracking algorithm robust to overlapping anatomies was proposed and validated on two scans of a lung cancer patient. Sub-millimeter tracking accuracy was observed, indicating the potential of this algorithm for real-time guidance

  7. Direct Imaging discovery of a second planet candidate around the possibly transiting planet host CVSO 30

    NASA Astrophysics Data System (ADS)

    Schmidt, T. O. B.; Neuhäuser, R.; Briceño, C.; Vogt, N.; Raetz, St.; Seifahrt, A.; Ginski, C.; Mugrauer, M.; Buder, S.; Adam, C.; Hauschildt, P.; Witte, S.; Helling, Ch.; Schmitt, J. H. M. M.

    2016-09-01

    Context. Direct imaging has developed into a very successful technique for the detection of exoplanets in wide orbits, especially around young stars. Directly imaged planets can be both followed astrometrically on their orbits and observed spectroscopically and thus provide an essential tool for our understanding of the early solar system. Aims: We surveyed the 25 Ori association for direct-imaging companions. This association has an age of only few million years. Among other targets, we observed CVSO 30, which has recently been identified as the first T Tauri star found to host a transiting planet candidate. Methods: We report on photometric and spectroscopic high-contrast observations with the Very Large Telescope, the Keck telescopes, and the Calar Alto observatory. They reveal a directly imaged planet candidate close to the young M3 star CVSO 30. Results: The JHK-band photometry of the newly identified candidate is at better than 1σ consistent with late-type giants, early-T and early-M dwarfs, and free-floating planets. Other hypotheses such as galaxies can be excluded at more than 3.5σ. A lucky imaging z' photometric detection limit z' = 20.5 mag excludes early-M dwarfs and results in less than 10 MJup for CVSO 30 c if bound. We present spectroscopic observations of the wide companion that imply that the only remaining explanation for the object is that it is the first very young (<10 Myr) L - T-type planet bound to a star, meaning that it appears bluer than expected as a result of a decreasing cloud opacity at low effective temperatures. Only a planetary spectral model is consistent with the spectroscopy, and we deduce a best-fit mass of 4-5 Jupiter masses (total range 0.6-10.2 Jupiter masses). Conclusions: This means that CVSO 30 is the first system in which both a close-in and a wide planet candidate are found to have a common host star. The orbits of the two possible planets could not be more different: they have orbital periods of 10.76 h and about 27

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

    NASA Astrophysics Data System (ADS)

    Belikov, Ruslan; Acend Team, Acesat Team

    2015-01-01

    Several mission concepts are being 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 (A and B), which is an extreme outlier among FGKM stars in terms of apparent habitable zone size. Specifically, Alpha Centauri habitable zones span about 0.5-1' in stellocentric angle, ~3x wider than around any other FGKM star. This enables a ~30cm visible light space telescope equipped with a modern high performance coronagraph or starshade to resolve the habitable zone at high contrast and directly image any potentially habitable planet that may exist in the system. Due to the extreme apparent brightness of the stars, exposure times can be as short as minutes with ideal components, or days with realistic ones. This makes it possible to do color photometry on potentially habitable planets 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.The raw contrast requirements for such an instrument can be relaxed to 1e-8 if the mission spends 2 years collecting tens of thousands of images on the same target, enabling a factor of 500-1000 speckle suppression in post processing. The light leak from both stars is controllable with a special wavefront control algorithm known as Multi-Star Wavefront Control (MSWC), which independently suppresses diffraction and aberrations from both stars using independent modes on the deformable mirror (see Thomas et al. at this conference).The presentation will describe the general studies and calculations in more detail and briefly present

  9. Image quality of a prototype direct conversion detector for digital mammography

    NASA Astrophysics Data System (ADS)

    Mainprize, James G.; Ford, Nancy L.; Yin, Shi; Tumer, Tumay O.; Yaffe, Martin J.

    1999-05-01

    A digital mammography system in which the x-ray sensitive device is a solid-state direct conversion detector is under development. This detector is a 1 mm thick silicon photodiode array hybridized to a CCD read-out, with a 50 micrometer pixel pitch. The detector is designed to be used in a slot-scanned system using time-delay integration (TDI) for signal acquisition. To handle the large signal generated in the photodiode, a novel read-out technique was used, in which charge was integrated 'on-chip' over a small number of rows, and the output of each of these sections was digitally summed 'off-chip' to produce the total integrated signal for each pixel in the image. This two-stage integration process not only allows easy acquisition of large signals, it effectively increases bit depth from 12 bits (for a single section) to approximately 16 (for the total integrated signal). The image quality of the device has been measured and compared to predictions based on cascaded linear systems theory. The resolution of the new detector was determined from the modulation transfer function (MTF) which was obtained from over-sampled edge spread functions (ESF). The ESF was measured in both the scan and slot directions from four repeated images of a tantalum edge. Noise power spectra (NPS) were determined from 40 repeated flat-field images at each of several x-ray exposures. By combining the MTF and NPS measurements, the detective quantum efficiency (DQE) was also determined. The MTF in the non-scanned direction was found to greater than 20% at 10 mm-1 and slightly lower in the scanned direction (approximately equals 10% at 10 mm-1). In all cases, the DQE was at least comparable to film-screen mammography receptors. The DQE at 120 mR detector exposure at zero spatial frequency ranged from 0.4 to 0.6 depending on the sample tested. Electronic noise was fairly low, contributing to less than plus or minus 7 ADU (out of a possible 98304 ADU). Future work will involve re-designing the

  10. Application of adaptive kinetic modelling for bias propagation reduction in direct 4D image reconstruction.

    PubMed

    Kotasidis, F A; Matthews, J C; Reader, A J; Angelis, G I; Zaidi, H

    2014-10-21

    Parametric imaging in thoracic and abdominal PET can provide additional parameters more relevant to the pathophysiology of the system under study. However, dynamic data in the body are noisy due to the limiting counting statistics leading to suboptimal kinetic parameter estimates. Direct 4D image reconstruction algorithms can potentially improve kinetic parameter precision and accuracy in dynamic PET body imaging. However, construction of a common kinetic model is not always feasible and in contrast to post-reconstruction kinetic analysis, errors in poorly modelled regions may spatially propagate to regions which are well modelled. To reduce error propagation from erroneous model fits, we implement and evaluate a new approach to direct parameter estimation by incorporating a recently proposed kinetic modelling strategy within a direct 4D image reconstruction framework. The algorithm uses a secondary more general model to allow a less constrained model fit in regions where the kinetic model does not accurately describe the underlying kinetics. A portion of the residuals then is adaptively included back into the image whilst preserving the primary model characteristics in other well modelled regions using a penalty term that trades off the models. Using fully 4D simulations based on dynamic [(15)O]H2O datasets, we demonstrate reduction in propagation-related bias for all kinetic parameters. Under noisy conditions, reductions in bias due to propagation are obtained at the cost of increased noise, which in turn results in increased bias and variance of the kinetic parameters. This trade-off reflects the challenge of separating the residuals arising from poor kinetic modelling fits from the residuals arising purely from noise. Nonetheless, the overall root mean square error is reduced in most regions and parameters. Using the adaptive 4D image reconstruction improved model fits can be obtained in poorly modelled regions, leading to reduced errors potentially propagating

  11. Reprocessing of Archival Direct Imaging Data of Herbig Ae/Be Stars

    NASA Astrophysics Data System (ADS)

    Safsten, Emily; Stephens, Denise C.

    2017-01-01

    Herbig Ae/Be (HAeBe) stars are intermediate mass (2-10 solar mass) pre-main sequence stars with circumstellar disks. They are the higher mass analogs of the better-known T Tauri stars. Observing planets within these young disks would greatly aid in understanding planet formation processes and timescales, particularly around massive stars. So far, only one planet, HD 100546b, has been confirmed to orbit a HAeBe star. With over 250 HAeBe stars known, and several observed to have disks with structures thought to be related to planet formation, it seems likely that there are as yet undiscovered planetary companions within the circumstellar disks of some of these young stars.Direct detection of a low-luminosity companion near a star requires high contrast imaging, often with the use of a coronagraph, and the subtraction of the central star's point spread function (PSF). Several processing algorithms have been developed in recent years to improve PSF subtraction and enhance the signal-to-noise of sources close to the central star. However, many HAeBe stars were observed via direct imaging before these algorithms came out. We present here current work with the PSF subtraction program PynPoint, which employs a method of principal component analysis, to reprocess archival images of HAeBe stars to increase the likelihood of detecting a planet in their disks.

  12. DIRECT IMAGING CONFIRMATION AND CHARACTERIZATION OF A DUST-ENSHROUDED CANDIDATE EXOPLANET ORBITING FOMALHAUT

    SciTech Connect

    Currie, Thayne; Debes, John; Rodigas, Timothy J.; Burrows, Adam; Itoh, Yoichi; Fukagawa, Misato; Kenyon, Scott J.; Kuchner, Marc; Matsumura, Soko

    2012-12-01

    We present Subaru/IRCS J-band data for Fomalhaut and a (re)reduction of archival 2004-2006 HST/ACS data first presented by Kalas et al. We confirm the existence of a candidate exoplanet, Fomalhaut b, in both the 2004 and 2006 F606W data sets at a high signal-to-noise ratio. Additionally, we confirm the detection at F814W and present a new detection in F435W. Fomalhaut b's space motion may be consistent with it being in an apsidally aligned, non-debris ring-crossing orbit, although new astrometry is required for firmer conclusions. We cannot confirm that Fomalhaut b exhibits 0.7-0.8 mag variability cited as evidence for planet accretion or a semi-transient dust cloud. The new, combined optical spectral energy distribution and IR upper limits confirm that emission identifying Fomalhaut b originates from starlight scattered by small dust, but this dust is most likely associated with a massive body. The Subaru and IRAC/4.5 {mu}m upper limits imply M < 2 M{sub J} , still consistent with the range of Fomalhaut b masses needed to sculpt the disk. Fomalhaut b is very plausibly 'a planet identified from direct imaging' even if current images of it do not, strictly speaking, show thermal emission from a directly imaged planet.

  13. Directional ocean wave measurements in a coastal setting using a focused array imaging radar

    SciTech Connect

    Frasier, S.J.; Liu, Y.; Moller, D.; McIntosh, R.E.; Long, C.

    1995-03-01

    A unique focused array imaging Doppler radar was used to measure directional spectra of ocean surface waves in a nearshore experiment performed on the North Carolina Outer Banks. Radar images of the ocean surface`s Doppler velocity were used to generate two dimensional spectra of the radial component of the ocean surface velocity field. These are compared to simultaneous in-situ measurements made by a nearby array of submerged pressure sensors. Analysis of the resulting two-dimensional spectra include comparisons of dominant wave lengths, wave directions, and wave energy accounting for relative differences in water depth at the measurement locations. Limited estimates of the two-dimensional surface displacement spectrum are derived from the radar data. The radar measurements are analogous to those of interferometric synthetic aperture radars (INSAR), and the equivalent INSAR parameters are shown. The agreement between the remote and in-situ measurements suggests that an imaging Doppler radar is effective for these wave measurements at near grazing incidence angles.

  14. Direction-Dependent Effects In Wide-Field Wideband Full-Stokes Radio Imaging

    NASA Astrophysics Data System (ADS)

    Jagannathan, P.; Bhatanagar, S.; Rau, U.; Taylor, R.

    2015-09-01

    Synthesis imaging in radio astronomy is affected by instrumental and atmospheric effects which introduce direction-dependent (DD) 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 wide-band full Stokes power pattern of the Karl G. Jansky Very Large Array (VLA) antennas to demonstrate the level of errors arising from direction-dependent gains and their non-neglegible impact on upcoming sky surveys such as the VLASS. DD corrections through hybrid projection algorithms are computationally expensive to perform. A highly parallel implementation through high performance computing architectures is the only feasible way of applying these corrections to the large data sizes of these upcoming surveys.

  15. Subaru Direct Imaging Survey of Wide-Orbit Exoplanets and Solar-System-Scale Disks

    NASA Astrophysics Data System (ADS)

    Tamura, Motohide

    2015-08-01

    SEEDS (Strategic Explorations of Exoplanets and Disks with Subaru) is the first Subaru Strategic Program, whose aim is to conduct a direct imaging survey for giant planets as well as protoplanetary/debris disks at a few to a few tens of AU region around 500 nearby solar-type or more massive young stars devoting 120 Subaru nights for 5 years from 2009. The targets are composed of five categories spanning the ages of ~1 Myr to ~1 Gyr. Some RV-planet targets with older ages are also observed. We describe this survey and present its main results. The topics include (1) statistic of wide-orbit planets, (2) detection and characterization of one of the most lowest-mass planet via direct imaging. (3) detection of a super-Jupiter around the most massive star ever imaged, (4) detection of companions around retrograde exoplanet, (5) the discovery of unprecedentedly detailed structures of more than a dozen of protoplanetary disks and some debris disks. The detected structures such as wide gaps and spirals arms of a Solar-system scale could be signpost of planet.

  16. Direct imaging of the magnetization reversal in microwires using all-MOKE microscopy

    NASA Astrophysics Data System (ADS)

    Stupakiewicz, A.; Chizhik, A.; Tekielak, M.; Zhukov, A.; Gonzalez, J.; Maziewski, A.

    2014-10-01

    We report a method of imaging of the magnetization reversal process using analysis of real-time images of magnetic domain structures in cylindrically shaped microwires. This method uses wide-field polarizing optical microscopy and is based on the magneto-optical Kerr effect (MOKE). The aperture diaphragm in MOKE microscope was used to control the incident angles of the light rays that reached the non-planar surface of the microwire and also determined the MOKE geometries. The movement of the non-central position of the hole in this diaphragm leads to a change in the orientation of the plane of incidence of the light along the perpendicular or the parallel direction to the axial direction of the wire. The visualization of the surface magnetic domain structures is obtained using polar and longitudinal MOKE geometries. The hysteresis loops were obtained by plotting the averaged image contrast as a function of the external magnetic field. The separation of the all-magnetization components is performed using different MOKE geometries in a microscope. We demonstrate the use of vector magnetometry to analyze the orientation of the magnetization in a cylindrically shaped microwire under the influence of an external magnetic field.

  17. Atmospheric circulation of brown dwarfs and directly imaged extrasolar giant planets with active clouds

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam

    2016-10-01

    Observational evidence have suggested active meteorology in the atmospheres of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs). In particular, a number of surveys for brown dwarfs showed that near-IR brightness variability is common for L and T dwarfs. Directly imaged EGPs share similar observations, and can be viewed as low-gravity versions of BDs. Clouds are believed to play the major role in shaping the thermal structure, dynamics and near-IR flux of these atmospheres. So far, only a few studies have been devoted to atmospheric circulation and the implications for observations of BDs and directly EGPs, and yet no global model includes a self-consistent active cloud formation. Here we present preliminary results from the first global circulation model applied to BDs and directly imaged EGPs that can properly treat absorption and scattering of radiation by cloud particles. Our results suggest that horizontal temperature differences on isobars can reach up to a few hundred Kelvins, with typical horizontal length scale of the temperature and cloud patterns much smaller than the radius of the object. The combination of temperature anomaly and cloud pattern can result in moderate disk-integrated near-IR flux variability. Wind speeds can reach several hundred meters per second in cloud forming layers. Unlike Jupiter and Saturn, we do not observe stable zonal jet/banded patterns in our simulations. Instead, our simulated atmospheres are typically turbulent and dominated by transient vortices. The circulation is sensitive to the parameterized cloud microphysics. Under some parameter combinations, global-scale atmospheric waves can be triggered and maintained. These waves induce global-scale temperature anomalies and cloud patterns, causing large (up to several percent) disk-integrated near-IR flux variability. Our results demonstrate that the commonly observed near-IR brightness variability for BDs and directly imaged EGPs can be explained by the

  18. Directional Histogram Ratio at Random Probes: A Local Thresholding Criterion for Capillary Images

    PubMed Central

    Lu, Na; Silva, Jharon; Gu, Yu; Gerber, Scott; Wu, Hulin; Gelbard, Harris; Dewhurst, Stephen; Miao, Hongyu

    2013-01-01

    With the development of micron-scale imaging techniques, capillaries can be conveniently visualized using methods such as two-photon and whole mount microscopy. However, the presence of background staining, leaky vessels and the diffusion of small fluorescent molecules can lead to significant complexity in image analysis and loss of information necessary to accurately quantify vascular metrics. One solution to this problem is the development of accurate thresholding algorithms that reliably distinguish blood vessels from surrounding tissue. Although various thresholding algorithms have been proposed, our results suggest that without appropriate pre- or post-processing, the existing approaches may fail to obtain satisfactory results for capillary images that include areas of contamination. In this study, we propose a novel local thresholding algorithm, called directional histogram ratio at random probes (DHR-RP). This method explicitly considers the geometric features of tube-like objects in conducting image binarization, and has a reliable performance in distinguishing small vessels from either clean or contaminated background. Experimental and simulation studies suggest that our DHR-RP algorithm is superior over existing thresholding methods. PMID:23525856

  19. Direct Geolocation of Satellite Images with the EO-CFI Libraries

    NASA Astrophysics Data System (ADS)

    de Miguel, Eduardo; Prado, Elena; Estebanez, Monica; Martin, Ana I.; Gonzalez, Malena

    2016-08-01

    The INTA Remote Sensing Laboratory has implemented a tool for the direct geolocation of satellite images. The core of the tool is a C code based on the "Earth Observation Mission CFI SW" from ESA. The tool accepts different types of inputs for satellite attitude (euler angles, quaternions, default attitude models). Satellite position can be provided either in ECEF or ECI coordinates. The line of sight of each individual detector is imported from an external file or is generated by the tool from camera parameters. Global DEM ACE2 is used to define ground intersection of the LOS.The tool has been already tailored for georeferencing images from the forthcoming Spanish Earth Observation mission SEOSat/Ingenio, and for the camera APIS onboard the INTA cubesat OPTOS. The next step is to configure it for the geolocation of Sentinel 2 L1b images.The tool has been internally validated by different means. This validation shows that the tool is suitable for georeferencing images from high spatial resolution missions. As part of the validation efforts, a code for simulating orbital info for LEO missions using EO-CFI has been produced.

  20. Tomographic image reconstruction from incomplete view data by convex projections and direct fourier inversion.

    PubMed

    Sezan, M; Stark, H

    1984-01-01

    We consider the problem of reconstructing CAT imagery by the direct Fourier method (DFM) when not all view data are available. To restore the missing information we use the method of projections onto convex sets (POCS). POCS is a recursive image restoration technique that finds a solution consistent with the measured data and a priori known constraints in both the space and Fourier domain. Because DFM reconstruction is a frequency-domain technique it is ideally matched to POCS restoration when, for one reason or another, we are forced to generate an image from a less than complete set of view data. We design and apply an algorithm (PRDF) which interpolates/extrapolates the missing Fourier domain information by POCS and reconstructs an image by DFM. A simulated human thorax cross section is restored and reconstructed. The restorations using POCS are compared with the Gerchberg-Papoulis extrapolation method and shown to be superior. Applications of PRDF to other types of medical imaging modalities are discussed.

  1. DIRECT IMAGING DETECTION OF METHANE IN THE ATMOSPHERE OF GJ 504 b

    SciTech Connect

    Janson, Markus; Brandt, Timothy D.; Kuzuhara, Masayuki; Spiegel, David S.; Thalmann, Christian; Currie, Thayne; Bonnefoy, Mickaël; Zimmerman, Neil; Schlieder, Joshua; Brandner, Wolfgang; Feldt, Markus; Sorahana, Satoko; Kotani, Takayuki; Hashimoto, Jun; Kusakabe, Nobuhiko; Kudo, Tomoyuki; Egner, Sebastian; Abe, Lyu; Carson, Joseph C.; Goto, Miwa; and others

    2013-11-20

    Most exoplanets detected by direct imaging thus far have been characterized by relatively hot (≳1000 K) and cloudy atmospheres. A surprising feature in some of their atmospheres has been a distinct lack of methane, possibly implying non-equilibrium chemistry. Recently, we reported the discovery of a planetary companion to the Sun-like star GJ 504 using Subaru/HiCIAO within the Strategic Exploration of Exoplanets and Disks with Subaru survey. The planet is substantially colder (<600 K) than previously imaged planets, and has indications of fewer clouds, which implies that it represents a new class of planetary atmospheres with expected similarities to late T-type brown dwarfs in the same temperature range. If so, one might also expect the presence of significant methane absorption, which is characteristic of such objects. Here, we report the detection of deep methane absorption in the atmosphere of GJ 504 b, using the Spectral Differential Imaging mode of HiCIAO to distinguish the absorption features around 1.6 μm. We also report updated JHK photometry based on new K {sub s}-band data and a re-analysis of the existing data. The results support the notion that GJ 504 b has atmospheric properties distinct from other imaged exoplanets, and will become a useful reference object for future planets in the same temperature range.

  2. Joint geometric and photometric direct image registration based on Lie algebra parameterization

    NASA Astrophysics Data System (ADS)

    Li, Chenxi; Shi, Zelin; Liu, Yunpeng

    2016-10-01

    In this paper, we consider direct image registration problem which estimate the geometric and photometric transformations between two images. The efficient second-order minimization method (ESM) is based on a second-order Taylor series of image differences without computing the Hessian under brightness constancy assumption. This can be done due to the fact that the considered geometric transformations is Lie group and can be parameterized by its Lie algebra. In order to deal with lighting changes, we extend ESM to the compositional dual efficient second-order minimization method (CDESM). In our approach, the photometric transformations is parameterized by its Lie algebra with compositional operation, which is similar to that of geometric transformations. Our algorithm can give a second-order approximation of image differences with respect to geometric and photometric parameters. The geometric and photometric parameters are simultaneously obtained by non-linear least-square optimization. Our algorithm preserves the advantages of the original ESM method which has high convergence rate and large capture radius. Experimental results show that our algorithm is more robust to lighting changes and has higher registration accuracy compared to previous algorithms.

  3. Calculation of grain boundary normals directly from 3D microstructure images

    DOE PAGES

    Lieberman, E. J.; Rollett, A. D.; Lebensohn, R. A.; ...

    2015-03-11

    The determination of grain boundary normals is an integral part of the characterization of grain boundaries in polycrystalline materials. These normal vectors are difficult to quantify due to the discretized nature of available microstructure characterization techniques. The most common method to determine grain boundary normals is by generating a surface mesh from an image of the microstructure, but this process can be slow, and is subject to smoothing issues. A new technique is proposed, utilizing first order Cartesian moments of binary indicator functions, to determine grain boundary normals directly from a voxelized microstructure image. In order to validate the accuracymore » of this technique, the surface normals obtained by the proposed method are compared to those generated by a surface meshing algorithm. Specifically, the local divergence between the surface normals obtained by different variants of the proposed technique and those generated from a surface mesh of a synthetic microstructure constructed using a marching cubes algorithm followed by Laplacian smoothing is quantified. Next, surface normals obtained with the proposed method from a measured 3D microstructure image of a Ni polycrystal are used to generate grain boundary character distributions (GBCD) for Σ3 and Σ9 boundaries, and compared to the GBCD generated using a surface mesh obtained from the same image. Finally, the results show that the proposed technique is an efficient and accurate method to determine voxelized fields of grain boundary normals.« less

  4. Calculation of grain boundary normals directly from 3D microstructure images

    SciTech Connect

    Lieberman, E. J.; Rollett, A. D.; Lebensohn, R. A.; Kober, E. M.

    2015-03-11

    The determination of grain boundary normals is an integral part of the characterization of grain boundaries in polycrystalline materials. These normal vectors are difficult to quantify due to the discretized nature of available microstructure characterization techniques. The most common method to determine grain boundary normals is by generating a surface mesh from an image of the microstructure, but this process can be slow, and is subject to smoothing issues. A new technique is proposed, utilizing first order Cartesian moments of binary indicator functions, to determine grain boundary normals directly from a voxelized microstructure image. In order to validate the accuracy of this technique, the surface normals obtained by the proposed method are compared to those generated by a surface meshing algorithm. Specifically, the local divergence between the surface normals obtained by different variants of the proposed technique and those generated from a surface mesh of a synthetic microstructure constructed using a marching cubes algorithm followed by Laplacian smoothing is quantified. Next, surface normals obtained with the proposed method from a measured 3D microstructure image of a Ni polycrystal are used to generate grain boundary character distributions (GBCD) for Σ3 and Σ9 boundaries, and compared to the GBCD generated using a surface mesh obtained from the same image. Finally, the results show that the proposed technique is an efficient and accurate method to determine voxelized fields of grain boundary normals.

  5. Direct Imaging Detection of Methane in the Atmosphere of GJ 504 b

    NASA Technical Reports Server (NTRS)

    Janson, Markus; Brandt, Timothy; Kuzuhara, Masayuki; Spiegel, David; Thalmann, Christian; Currie, Thayne; Bonnefoy, Mickael; Zimmerman, Neil; Sorahana, Satoko; Kotani, Takayuki; Schlieder, Joshua; Hashimoto, Jun; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Abe, Lyu; Brandner, Wolfgang; Carson, Joseph; Egner, Sebastian; Feldt, Markus; Goto, Miwa; Grady, Carol; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; McElwain, Michael

    2013-01-01

    Most exoplanets detected by direct imaging so far have been characterized by relatively hot (approximately greater than1000 K) and cloudy atmospheres. A surprising feature in some of their atmospheres has been a distinct lack of methane, possibly implying non-equilibrium chemistry. Recently, we reported the discovery of a planetary companion to the Sun-like star GJ 504 using Subaru/HiCIAO within the SEEDS survey. The planet is substantially colder (less than 600 K) than previously imaged planets, and has indications of fewer clouds, which implies that it represents a new class of planetary atmospheres with expected similarities to late T-type brown dwarfs in the same temperature range. If so, one might also expect the presence of significant methane absorption, which is characteristic of such objects. Here, we report the detection of deep methane absorption in the atmosphere of GJ 504 b, using the Spectral Differential Imaging mode of HiCIAO to distinguish the absorption feature around 1.6 micrometers. We also report updated JHK photometry based on new K(sub s)-band data and a re-analysis of the existing data. The results support the notion that GJ 504 b has atmospheric properties distinct from other imaged exoplanets, and will become a useful reference object for future planets in the same temperature range.

  6. Direct volume access by an improved electro-holography image generator

    NASA Astrophysics Data System (ADS)

    Takahashi, Hideya; Tanaka, Kazuyuki; Okamoto, Hideki; Ueda, Hiroaki; Shimizu, Eiji

    1995-04-01

    A CAD system with electronic holography is expected to provide ideal designing environments to feel and touch truly 3D images directly. However, interactivity and real-time computation of holographic fringe patterns are the essential requirements to realize it. This paper presents two different types of 3D images creating system. One consists of a 3D pointing device and an electro-holography system with an acousto-optical modulator which was proposed by Prof. Benton in 1989. The other consists of a 3D pointing device and an electro-holography system with a liquid crystal device. We also propose an effective method not depending on the total number of points in the scene and apply it to the designing tool by only appending points in a electro-holography system with a 3D input device.

  7. Moderate Resolution Spectroscopy of Directly Imaged Exoplanets: Formation, Chemistry, and Clouds

    NASA Astrophysics Data System (ADS)

    Konopacky, Quinn

    More than twenty years after the discovery of the first planet orbiting a star other than the Sun, it is now clear that extrasolar planets are ubiquitous. With each new discovery, new questions are raised about planet formation and evolution that challenge commonly held assumptions. Few currently known exoplanets reside at separations beyond the ice line, forcing extrapolation when developing a theory to explain planet formation on all scales. In the next several years, the number of known exoplanets at wide separations will increase dramatically as a new era in exoplanet discovery commences - the era of direct imaging. By using techniques to achieve high angular resolution on large (8-10 meter) ground based telescopes, it is now possible to resolve and study the light coming from widely separated gas giant planets at unprecedented levels of detail. Our group has pioneered observational and theoretical techniques that have provided spectra of directly imaged planets at resolutions and SNR that are rarely obtained for exoplanets. By using adaptive optics fed integral field spectrographs, we have extracted spectra at R 4000 in the near infrared, resolving individual molecular features from species such as water, carbon monoxide, and methane. These species have been used for detailed measurements of the ratio of carbon and oxygen in these planetary spectra. We propose to advance beyond these initial measurements and pursue a systematic program of near-infrared spectroscopy covering a suite of directly imaged exoplanets at similarly high spectral resolutions. Multiple surveys with newly commissioned instruments for direct imaging are now underway with the goal of substantially increasing the number of known directly imaged giant planets. The photometric and/or very low resolution spectroscopic data provided by these surveys are useful for rough planet characterization. Advancing our understanding of these planets, however, is best achieved through higher spectral

  8. Direct x-ray imaging system using an amplified metal-oxide-semiconductor imager in the 4-13-nm wavelength region

    NASA Astrophysics Data System (ADS)

    Haga, Tsuneyuki; Kinoshita, Hiroo

    1995-10-01

    We describe a direct x-ray imaging system that uses an amplified metal-oxide-semiconductor imager to detect soft x rays directly for real-time imaging. From the absolute sensitivity of this system as measured through the use of a monochromatic synchrotron radiation beam and a GaAsP Schottky-type photodiode, the minimum sensitivity at a wavelength of 13 nm was estimated to be greater than 108 photons mm-2. This is sufficient to detect soft x rays directly for real-time imaging. Onion cell observations at wavelengths of 4.3 and 4.6 nm indicate that x-ray absorption by the carbon in the cells was detected. This is a promising imaging system for the soft x-ray region in which conventional CCD's are difficult to use.

  9. Beginning a new chapter in the characterization of directly imaged exoplanets: the science of MIRI

    NASA Astrophysics Data System (ADS)

    Danielski, Camilla; Baudino, Jean-Loup; Lagage, Pierre-Olivier; Boccaletti, Anthony; Bézard, Bruno

    2016-10-01

    The next major space facility to characterize the atmosphere of exoplanets will be the JWST. Among its instruments the Mid-Infrared instrument (MIRI) will perform the first ever characterization of young giant exoplanets observed by direct imaging in the 5 -28 microns wavelength range.Retrieving the precise set of parameters of these objects, such as luminosity, temperature, surface gravity, mass, and age is extremely important as it supplies information about the initial entropy of the planets and hence it allows us to shed light on their formation mechanism.The new extreme adaptive optic cameras (e.g. SPHERE, GPI) are already providing excellent constraints on these parameters, but the spectral window in which they are operating is limited to near IR so that the uncertainties are still significant. Therefore, since observations taken on a longer wavelength range are mandatory for reducing them, MIRI will be playing a key role in this new chapter of exoplanetary characterization.Furthermore, MIRI will give us the opportunity to probe for the first time the presence of ammonia in the atmosphere of the coldest known young giants (T < 1000 K). Notice that the ammonia spectral signature is a further useful indicator of equilibrium and temperature in the planetary atmosphere.In this work we have used the Exoplanet Radiative-convective Equilibrium Model (Exo-REM), developed by Baudino et al. (2015) and tailored for directly imaged exoplanets, to quantify the constraints on the planetary parameters that MIRI will bring.We simulated the MIRI coronographic and Low-resolution spectrometer observations for a set of 13 known directly imaged exoplanetary systems. Subsequently, taking into account various source of noise and the photometric precision, we show to which accuracy the exoplanetary parameters (temperature, gravity, chemical composition) can be determined when adding MIRI observations, and we provide the significance of the ammonia detection.

  10. Simulation of a method to directly image exoplanets around multiple stars systems

    NASA Astrophysics Data System (ADS)

    Thomas, Sandrine J.; Bendek, Eduardo; Belikov, Ruslan

    2014-08-01

    Direct imaging of extra-solar planets has now become a reality, especially with the deployment and commissioning of the first generation of specialized ground-based instruments such as the GPI, SPHERE, P1640 and SCExAO. These systems will allow detection of planets 107 times fainter than their host star. For space- based missions, such as EXCEDE, EXO-C, EXO-S, WFIRST/AFTA, different teams have shown in laboratories contrasts reaching 10-10 within a few diffraction limits from the star using a combination of a coronagraph to suppress light coming from the host star and a wavefront control system. These demonstrations use a de- formable mirror (DM) to remove residual starlight (speckles) created by the imperfections of telescope. However, all these current and future systems focus on detecting faint planets around a single host star or unresolved bi- naries/multiples, while several targets or planet candidates are located around nearby binary stars such as our neighbor star Alpha Centauri. Until now, it has been thought that removing the light of a companion star is impossible with current technology, excluding binary star systems from target lists of direct imaging missions. Direct imaging around binaries/multiple systems at a level of contrast allowing Earth-like planet detection is challenging because the region of interest, where a dark zone is essential, is contaminated by the light coming from the hosts star companion. We propose a method to simultaneously correct aberrations and diffraction of light coming from the target star as well as its companion star in order to reveal planets orbiting the target star. This method works even if the companion star is outside the control region of the DM (beyond its half-Nyquist frequency), by taking advantage of aliasing effects.

  11. THE LEECH EXOPLANET IMAGING SURVEY: CHARACTERIZATION OF THE COLDEST DIRECTLY IMAGED EXOPLANET, GJ 504 b, AND EVIDENCE FOR SUPERSTELLAR METALLICITY

    SciTech Connect

    Skemer, Andrew J.; Leisenring, Jarron; Bailey, Vanessa; Hinz, Philip; Defrére, Denis; Apai, Dániel; Close, Laird; Eisner, Josh; Morley, Caroline V.; Fortney, Jonathan; Zimmerman, Neil T.; Buenzli, Esther; Bonnefoy, Mickael; Biller, Beth; Brandner, Wolfgang; Skrutskie, Michael F.; Esposito, Simone; Crepp, Justin R.; De Rosa, Robert J.; Desidera, Silvano; and others

    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: T{sub eff} = 544 ± 10 K, g < 600 m s{sup −2}, [M/H] = 0.60 ± 0.12, cloud opacity parameter of f{sub sed} = 2–5, R = 0.96 ± 0.07 R{sub Jup}, and log(L) = −6.13 ± 0.03 L{sub ⊙}, implying a hot start mass of 3–30 M{sub jup} 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.

  12. Direct Imaging of Deformation and Disorder in Extended-Chain Polymer Fibers

    DTIC Science & Technology

    1991-03-01

    Lenhert, T. J. Resch, and W. W. Adams, "Molecular Packing and Crystalline Order in Polybenzobisoxazole and Polybenzobisthiazole Fibers ", in...WL-TR-91-4011 AiAh 1A0 DIRECT IMAGING OF DEFORMATION AND DISORDER IN EXTENDED-CHAIN POLYMER FIBERS David C. Martin Department of Polymer Science and...Deformation and Disorder in Extended-Chain Polymer Fibers 12. PERSONAL AUTHOR(S) David C. Martin 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year

  13. Connecting Young Brown Dwarfs and Directly Imaged Gas-Giant Planets

    NASA Astrophysics Data System (ADS)

    Liu, Michael; Dupuy, Trent; Allers, Katelyn; Aller, Kimberly; Best, William; Magnier, Eugene

    2015-12-01

    Direct detections of gas-giant exoplanets and discoveries of young (~10-100 Myr) field brown dwarfs from all-sky surveys are strengthening the link between the exoplanet and brown dwarf populations, given the overlapping ages, masses, temperatures, and surface gravities. In light of the relatively small number of directly imaged planets and the modest associated datasets, the large census of young field brown dwarfsprovides a compelling laboratory for enriching our understanding of both classes of objects. However, work to date on young field objects has typically focused on individual discoveries.We present a large comprehensive study of the youngest field brown dwarfs, comprising both previously known objects and our new discoveries from the latest wide-field surveys (Pan-STARRS-1 and WISE). With masses now extending down to ~5 Jupiter masses, these objects have physical properties that largely overlap young gas-giant planets and thus are promising analogs for studying exoplanet atmospheres at unparalleled S/N, spectral resolution, and wavelength coverage. We combine high-quality spectra and parallaxes to determine spectral energy distributions, luminosities, temperatures, and ages for young field objects. We demonstrate that this population spans a continuum in the color-magnitude diagram, thereby forming a bridge between the hot and cool extremes of directly imaged planets. We find that the extremely dusty properties of the planets around 2MASS J1207-39 and HR 8799 do occur in some young brown dwarfs, but these properties do not have a simple correspondence with age, perhaps contrary to expectations. We find young field brown dwarfs can have unusually low temperatures and suggest a new spectral type-temperature scale appropriate for directly imaged planets.To help provide a reference for extreme-contrast imaging surveys, we establish a grid of spectral standards and benchmarks, based on membership in nearby young moving groups, in order to calibrate gravity

  14. A digital receiver module with direct data acquisition for magnetic resonance imaging systems.

    PubMed

    Tang, Weinan; Sun, Hongyu; Wang, Weimin

    2012-10-01

    A digital receiver module for magnetic resonance imaging (MRI) with detailed hardware implementations is presented. The module is based on a direct sampling scheme using the latest mixed-signal circuit design techniques. A single field-programmable gate array chip is employed to perform software-based digital down conversion for radio frequency signals. The modular architecture of the receiver allows multiple acquisition channels to be implemented on a highly integrated printed circuit board. To maintain the phase coherence of the receiver and the exciter in the context of direct sampling, an effective phase synchronization method was proposed to achieve a phase deviation as small as 0.09°. The performance of the described receiver module was verified in the experiments for both low- and high-field (0.5 T and 1.5 T) MRI scanners and was compared to a modern commercial MRI receiver system.

  15. Direct Imaging of DNA/Lipid Complexes Interacting with Liposome Surfaces and Fibroblasts

    NASA Astrophysics Data System (ADS)

    Lin, Alison J.; Idziak, Stefan H. J.; Rädler, Joachim; George, Cyril X.; Safinya, Cyrus R.; Samuel, Charles E.

    1996-03-01

    Video-enhanced light microscopy techniques (phase contrast, differential interference contrast, and fluorescence) were used for direct imaging of the structure and dynamics of nucleic acid-cationic liposome complexes both on liposomes (a model cell) and within the cytoplasm of Mouse L929 Fibroblasts. The experiments are designed to enable us to correlate the complex's structure to the transfection efficiencies (i.e. the uptake and expression of nucleic acid) in animal cells. The ultimate goal of the project is to design an optimal non-viral vector (carrier of nucleic acids). Fluorescence labeling of both the lipid and nucleic acid components is used for visualization experiments at the level of single complexes interacting with a single cell (e.g. a giant liposome or an isolated mammalian cell). This allows us to follow the temporal path of a complex. Direct motion versus random Brownian diffusion are readily distinguished. Micropipettes were used for placement of cells and microinjection into cells.

  16. Image-guided spine surgery: state of the art and future directions

    PubMed Central

    Shafizadeh, Sven; Rixen, Dieter; Paffrath, Thomas; Bouillon, Bertil; Steinhausen, Eva S.; Baethis, Holger

    2009-01-01

    Navigation technology is a widely available tool in spine surgery and has become a part of clinical routine in many centers. The issue of where and when navigation technology should be used is still an issue of debate. It is the aim of this study to give an overview on the current knowledge concerning the technical capabilities of image-guided approaches and to discuss possible future directions of research and implementation of this technique. Based on a Medline search total of 1,462 publications published until October 2008 were retrieved. The abstracts were scanned manually for relevance to the topics of navigated spine surgery in the cervical spine, the thoracic spine, the lumbar spine, as well as ventral spine surgery, radiation exposure, tumor surgery and cost-effectivity in navigated spine surgery. Papers not contributing to these subjects were deleted resulting in 276 papers that were included in the analysis. Image-guided approaches have been investigated and partially implemented into clinical routine in virtually any field of spine surgery. However, the data available is mostly limited to small clinical series, case reports or retrospective studies. Only two RCTs and one metaanalysis have been retrieved. Concerning the most popular application of image-guided approaches, pedicle screw insertion, the evidence of clinical benefit in the most critical areas, e.g. the thoracic spine, is still lacking. In many other areas of spine surgery, e.g. ventral spine surgery or tumor surgery, image-guided approaches are still in an experimental stage. The technical development of image-guided techniques has reached a high level as the accuracies that can be achieved technically meet the anatomical demands. However, there is evidence that the interaction between the surgeon (‘human factor’) and the navigation system is a source of inaccuracy. It is concluded that more effort needs to be spend to understand this interaction. PMID:19763640

  17. Handheld directional reflectometer: an angular imaging device to measure BRDF and HDR in real time

    NASA Astrophysics Data System (ADS)

    Mattison, Phillip R.; Dombrowski, Mark S.; Lorenz, James M.; Davis, Keith J.; Mann, Harley C.; Johnson, Philip; Foos, Bryan

    1998-10-01

    Many applications require quantitative measurements of surface light scattering, including quality control on production lines, inspection of painted surfaces, inspection of field repairs, etc. Instruments for measuring surface scattering typically fall into two main categories, namely bidirectional reflectometers, which measure the angular distribution of scattering, and hemispherical directional reflectometers, which measure the total scattering into the hemisphere above the surface. Measurement of the bi-directional reflectance distribution function (BRDF) gives the greatest insight into how light is scattered from a surface. Measurements of BRDF, however, are typically very lengthy measurements taken by moving a source and detector to map the scattering. Since BRDF has four angular degrees of freedom, such measurements can require hours to days to complete. Instruments for measuring BRDF are also typically laboratory devices, although a field- portable bi-directional reflectometer does exist. Hemispherical directional reflectance (HDR) is a much easier measurement to make, although care must be taken to use the proper methodology when measuring at wavelengths beyond 10 micrometer, since integrating spheres (typically used to make such measurements) are very energy inefficient and lose their integrating properties at very long wavelengths. A few field- portable hemispherical directional reflectometers do exist, but typically measure HDR only at near-normal angles. Boeing Defense and Space Group and Surface Optics Corporation, under a contract from the Air Force Research Laboratory, have developed a new hand-held instrument capable of measuring both BRDF and HDR using a unique, patented angular imaging technique. A combination of an hemi-ellipsoidal mirror and an additional lens translate the angular scatter from a surface into a two-dimensional spatial distribution, which is recorded by an imaging array. This configuration fully maps the scattering from a half

  18. Image based weighted center of proximity versus directly measured knee contact location during simulated gait

    PubMed Central

    Wang, Hongsheng; Chen, Tony; Koff, Matthew F.; Hutchinson, Ian D.; Gilbert, Susannah; Choi, Dan; Warren, Russell F.; Rodeo, Scott A.; Maher, Suzanne A.

    2014-01-01

    To understand the mechanical consequences of knee injury requires a detailed analysis of the effect of that injury on joint contact mechanics during activities of daily living. Three-dimensional (3D) knee joint geometric models have been combined with knee joint kinematics to dynamically estimate the location of joint contact during physiological activities – using a weighted center of proximity (WCoP) method. However, the relationship between the estimated WCoP and the actual location of contact has not been defined. The objective of this study was to assess the relationship between knee joint contact location as estimated using the image-based WCoP method, and a directly measured weighted center of contact (WCoC) method during simulated walking. To achieve this goal, we created knee specific models of six human cadaveric knees from magnetic resonance imaging. All knees were then subjected to physiological loads on a knee simulator intended to mimic gait. Knee joint motion was captured using a motion capture system. Knee joint contact stresses were synchronously recorded using a thin electronic sensor throughout gait, and used to compute WCoC for the medial and lateral plateaus of each knee. WCoP was calculated by combining knee kinematics with the MRI-based knee specific model. Both metrics were compared throughout gait using linear regression. The anteroposterior (AP) location of WCoP was significantly correlated with that of WCoC on both tibial plateaus in all specimens (P < 0.01, 95% confidence interval of Person’s coefficient r > 0), but the correlation was not significant in the mediolateral (ML) direction for 4/6 knees (P > 0.05). Our study demonstrates that while the location of joint contact obtained from 3D knee joint contact model, using the WCoP method, is significantly correlated with the location of actual contact stresses in the AP direction, that relationship is less certain in the ML direction. PMID:24837219

  19. Adaptive optics for direct detection of extrasolar planets: the Gemini Planet Imager

    NASA Astrophysics Data System (ADS)

    Macintosh, Bruce; Graham, James; Palmer, David; Doyon, Rene; Gavel, Don; Larkin, James; Oppenheimer, Ben; Saddlemyer, Leslie; Wallace, J. Kent; Bauman, Brian; Erikson, Darren; Poyneer, Lisa; Sivaramakrishnan, Anand; Soummer, Rémi; Veran, Jean-Pierre

    2007-04-01

    The direct detection of photons emitted or reflected by extrasolar planets, spatially resolved from their parent star, is a major frontier in the study of other solar systems. Direct detection will provide statistical information on planets in 5 50 AU orbits, inaccessible to current Doppler searches, and allow spectral characterization of radius, temperature, surface gravity, and perhaps composition. Achieving this will require new, dedicated, high-contrast instruments. One such system under construction is the Gemini Planet Imager (GPI). This combines a high-order/high-speed adaptive optics system to control wavefront errors from the Earth's atmosphere, an advanced coronagraph to block diffraction, ultrasmooth optics, a precision infrared interferometer to measure and correct systematic errors, and a integral field spectrograph/polarimeter to image and characterize target planetary systems. We predict that GPI will be able to detect planets with brightness less than 10-7 of their parent star, sufficient to observe warm self-luminous planets around a large population of targets. To cite this article: B. Macintosh et al., C. R. Physique 8 (2007).

  20. Direct monitoring changes of salbutamol concentration in serum by chemiluminescent imaging.

    PubMed

    Zhang, Canli; Zhang, Ruichao; Na, Na; Delanghe, Joris R; Ouyang, Jin

    2011-07-15

    We report in this manuscript, the use of direct ammonium persulfate-enhanced chemiluminescence (CL) imaging, to monitor changes to measure serum salbutamol concentration in subjects of different haptoglobin (Hp) phenotypes at different dosing time. It was noted that CL generated from Hp was decreased due to salbutamol's reducibility, which was used for monitoring salbutamol concentration in serum. The serum from the subjects treated by oral administration of salbutamol, was collected at different dosing time and was separated by polyacrylamide gel electrophoresis (PAGE) prior to the CL detection. According to CL images, samples were separated into three groups based on the Hp phenotypes. The curves of CL signal intensity versus time were obtained for each group, and we demonstrated that there were more significant variables on binding ability between groups. The maximum salbutamol concentration in the serum appeared after 4h, which was in agreement with the literature. In addition, the binding constants of salbutamol to Hp were determined by a fluorescence-based method, whose results were in agreement with the phenomenon of the greater salbutamol metabolism rate for Group Hp 1-1 than Group Hp 2-2. The presented method can monitor changes of salbutamol concentration in serum directly, making the procedures much simple, convenient, rapid and has the property of lower cost. It provided us with excellent reference information for the individual dosage regimen of different Hp groups, which hopefully could become a potential method for further pharmaceutical research.

  1. In Vivo Contrast-Enhanced MR Imaging of Direct Infusion into Rat Peripheral Nerves

    PubMed Central

    Chen, Xiaoming; Astary, Garrett W.; Mareci, Thomas H.; Sarntinoranont, Malisa

    2011-01-01

    Direct infusion, or convection-enhanced delivery (CED), into peripheral nerves may provide a method for delivering substances to the intrathecal space or specific fiber bundles entering the spinal cord. To better understand this potential delivery technique, we have characterized the extracellular transport of macromolecular agents from peripheral nerves to the spinal cord in magnetic resonance (MR) imaging studies. High-resolution dynamic contrast-enhanced MR imaging at 11.1 T was used to monitor and characterize in vivo the extracellular transport dynamics of Gd-DTPA-albumin tracer during CED into rat sciatic nerves. Extracellular tracers followed peripheral nerves towards the spinal cord and at vertebral levels L4 and L5 appeared to enter the cerebrospinal fluid and nerve roots. Uptake directly into spinal cord tissues (white and gray matter) appeared to be limited. Spatial distribution patterns within spinal cord regions depended on CED factors, including cannula placement, and underlying tissue structures including peripheral nerve branching and membrane structures at nerve root entry. The applied MR techniques allowed for visualization and quantification of tracer spread and distribution within the rat spinal cord region. The results show that CED into peripheral nerves provides an alternative route for delivering therapeutics to nerve roots and the intrathecal space surrounding the spinal cord. PMID:21809145

  2. Direct Imaging of a Two-Dimensional Silica Glass on Graphene

    NASA Astrophysics Data System (ADS)

    Huang, P. Y.; Kurasch, S.; Srivastava, A.; Skakalova, V.; Kotakoski, J.; Krasheninnikov, A. V.; Hovden, R. M.; Mao, Q.; Meyer, J. C.; Smet, J.; Muller, D. A.; Kaiser, U.

    2012-02-01

    Large-area graphene substrates [1] are a promising lab bench for synthesizing and characterizing novel low-dimensional materials such as two-dimensional (2D) glasses. Unlike 2D crystals such as graphene, 2D glasses are almost entirely unexplored--yet they have enormous applicability for understanding amorphous structures, which are difficult to probe in 3D. We report direct observations of the structure of an amorphous 2D silica supported on graphene. To our knowledge, these results represent the first discovery of an extended 2D glass. The 2D glass enables aberration-corrected scanning transmission electron microscopy and spectroscopy, producing the first atomically-resolved experimental images of a glass. The images strikingly resemble Zachariasen's seminal 1932 cartoons of a 2D continuous random network glass [2] and allow direct structural analyses not possible in 3D glassy materials. DFT calculations indicate that van der Waals interactions with graphene energetically favor the 2D structure over bulk SiO2, suggesting that graphene can be instrumental in stabilizing new 2D materials. [1] J. C. Meyer et al., Nature 454, 319--322 (2008). [2] W. H. Zachariasen, J. Am. Chem. Soc. 54, 3841--3851 (1932).

  3. Adaptive Optics for Direct Detection of Extrasolar Planets: The Gemini Planet Imager

    SciTech Connect

    Macintosh, B; Graham, J; Palmer, D; Doyon, R; Gavel, D; Larkin, J; Oppenheimer, B; Saddlemyer, L; Wallace, J K; Bauman, B; Erikson, D; Poyneer, L; Sivaramakrishnan, A; Soummer, R; Veran, J

    2007-04-24

    The direct detection of photons emitted or reflected by extrasolar planets, spatially resolved from their parent star, is a major frontier in the study of other solar systems. Direct detection will provide statistical information on planets in 5-50 AU orbits, inaccessible to current Doppler searches, and allow spectral characterization of radius, temperature, surface gravity, and perhaps composition. Achieving this will require new dedicated high-contrast instruments. One such system under construction is the Gemini Planet Imager (GPI.) This combines a high-order/high-speed adaptive optics system to control wavefront errors from the Earth's atmosphere, an advanced coronagraph to block diffraction, ultrasmooth optics, a precision infrared interferometer to measure and correct systematic errors, and a integral field spectrograph/polarimeter to image and characterize target planetary systems. We predict that GPI will be able to detect planets with brightness less than 10{sup -7} of their parent star, sufficient to observe warm self-luminous planets around a large population of targets.

  4. THE TRENDS HIGH-CONTRAST IMAGING SURVEY. II. DIRECT DETECTION OF THE HD 8375 TERTIARY

    SciTech Connect

    Crepp, Justin R.; Johnson, John Asher; Yantek, Scott M.; Howard, Andrew W.; Marcy, Geoff W.; Isaacson, Howard; Fischer, Debra A.; Wright, Jason T.; Feng Ying

    2013-07-01

    We present the direct imaging detection of a faint tertiary companion to the single-lined spectroscopic binary HD 8375 AB. Initially noticed as an 53 m s{sup -1} yr{sup -1} Doppler acceleration by Bowler et al., we have obtained high-contrast adaptive optics observations at Keck using NIRC2 that spatially resolve HD 8375 C from its host(s). Astrometric measurements demonstrate that the companion shares a common proper-motion. We detect orbital motion in a clockwise direction. Multiband relative photometry measurements are consistent with an early M-dwarf spectral type ({approx}M1V). Our combined Doppler and imaging observations place a lower-limit of m {>=} 0.297 M{sub Sun} on its dynamical mass. We also provide a refined orbit for the inner pair using recent radial velocity measurements obtained with the High Resolution Echelle Spectrometer. HD 8375 is one of many triple-star systems that are apparently missing in the solar neighborhood.

  5. DIRECT IMAGING IN THE HABITABLE ZONE AND THE PROBLEM OF ORBITAL MOTION

    SciTech Connect

    Males, Jared R.; Skemer, Andrew J.; Close, Laird M.

    2013-07-01

    High contrast imaging searches for exoplanets have been conducted on 2.4-10 m telescopes, typically at H band (1.6 {mu}m) and used exposure times of {approx}1 hr to search for planets with semi-major axes of {approx}> 10 AU. We are beginning to plan for surveys using extreme-AO systems on the next generation of 30 m class telescopes, where we hope to begin probing the habitable zones (HZs) of nearby stars. Here we highlight a heretofore ignorable problem in direct imaging: planets orbit their stars. Under the parameters of current surveys, orbital motion is negligible over the duration of a typical observation. However, this motion is not negligible when using large diameter telescopes to observe at relatively close stellar distances (1-10 pc), over the long exposure times (10-20 hr) necessary for direct detection of older planets in the HZ. We show that this motion will limit our achievable signal-to-noise ratio and degrade observational completeness. Even on current 8 m class telescopes, orbital motion will need to be accounted for in an attempt to detect HZ planets around the nearest Sun-like stars {alpha} Cen A and B, a binary system now known to harbor at least one planet. Here we derive some basic tools for analyzing this problem, and ultimately show that the prospects are good for de-orbiting a series of shorter exposures to correct for orbital motion.

  6. 4 pi direction sensitive gamma imager with RENA-3 readout ASIC

    NASA Astrophysics Data System (ADS)

    Du, Yanfeng; Li, Wen; Yanoff, Brian; Gordon, Jeffrey; Castleberry, Donald

    2007-09-01

    A 4π direction-sensitive gamma imager is presented, using a 1 cm 3 3D CZT detector from Yinnel Tech and the RENA-3 readout ASIC from NOVA R&D. The measured readout system electronic noise is around 4-5 keV FWHM for all anode channels. The measured timing resolution between two channels within a single ASIC is around 10 ns and the resolution is 30 ns between two separate ASIC chips. After 3D material non-uniformity and charge trapping corrections, the measured single-pixel-event energy resolution is around 1% for Cs-137 at 662 keV using a 1 cm 3 CZT detector from Yinnel Tech with an 8 x 8 anode pixel array at 1.15 mm pitch. The energy resolution for two pixel events is 2.9%. A 10 uCi Cs-137 point source was moved around the detector to test the image reconstruction algorithms and demonstrate the source direction detection capability. Accurate source locations were reconstructed with around 200 two-pixel events within a total energy window +/-10 keV around the 662 keV full energy peak. The angular resolution FWHM at four of the five positions tested was between 0.05-0.07 steradians.

  7. Mid-callosal plane determination using preferred directions from diffusion tensor images

    NASA Astrophysics Data System (ADS)

    Costa, André L.; Rittner, Letícia; Lotufo, Roberto A.; Appenzeller, Simone

    2015-03-01

    The corpus callosum is the major brain structure responsible for inter{hemispheric communication between neurons. Many studies seek to relate corpus callosum attributes to patient characteristics, cerebral diseases and psychological disorders. Most of those studies rely on 2D analysis of the corpus callosum in the mid-sagittal plane. However, it is common to find conflicting results among studies, once many ignore methodological issues and define the mid-sagittal plane based on precary or invalid criteria with respect to the corpus callosum. In this work we propose a novel method to determine the mid-callosal plane using the corpus callosum internal preferred diffusion directions obtained from diffusion tensor images. This plane is analogous to the mid-sagittal plane, but intended to serve exclusively as the corpus callosum reference. Our method elucidates the great potential the directional information of the corpus callosum fibers have to indicate its own referential. Results from experiments with five image pairs from distinct subjects, obtained under the same conditions, demonstrate the method effectiveness to find the corpus callosum symmetric axis relative to the axial plane.

  8. Flight Demonstration of a Milli-Arcsecond Optical Pointing System for Direct Exoplanet Imaging

    NASA Astrophysics Data System (ADS)

    Mendillo, Christopher; Chakrabarti, S.; Cook, T.; Hicks, B.

    2012-01-01

    The PICTURE (Planetary Imaging Concept Testbed Using a Rocket Experiment) sounding rocket attempted to use a white-light nulling interferometer to image the exozodiacal dust disk of Epsilon Eridani (K2V, 3.22 pc) in reflected visible light down to an inner radius of 3 AU. PICTURE launched from White Sands Missile Range on October 8th, 2011. Unfortunately, the main science telemetry channel was lost seconds into flight and no science data was recovered. However, on-board diagnostic data does show that PICTURE successfully demonstrated a fast (200 Hz) optical tracking system that provided 2 milli-arcsecond in-flight pointing stability, a thousand-fold improvement over the raw pointing of the rocket's attitude control system (ACS). The PICTURE flight provides heritage for a technology that will be a key component for many future direct exoplanet imaging missions. We present a spectral analysis of the 200 Hz tracking data in comparison to the 50 Hz ACS gyro data and we provide a precise measurement of the true ACS performance at frequencies higher than 5 Hz where the ACS gyros become noise limited. This work is funded by NASA grant: NNG05WC17G.

  9. Direct Fluorescent Imaging of Translocation and Unwinding by Individual DNA Helicases.

    PubMed

    Pavankumar, T L; Exell, J C; Kowalczykowski, S C

    2016-01-01

    The unique translocation and DNA unwinding properties of DNA helicases can be concealed by the stochastic behavior of enzyme molecules within the necessarily large populations used in ensemble experiments. With recent technological advances, the direct visualization of helicases acting on individual DNA molecules has contributed significantly to the current understanding of their mechanisms of action and biological functions. The combination of single-molecule techniques that enable both manipulation of individual protein or DNA molecules and visualization of their actions has made it possible to literally see novel and unique biochemical characteristics that were previously masked. Here, we describe the execution and use of single-molecule fluorescence imaging techniques, focusing on methods that include optical trapping in conjunction with epifluorescent imaging, and also surface immobilization in conjunction with total internal reflection fluorescence visualization. Combined with microchannel flow cells and microfluidic control, these methods allow individual fluorescently labeled protein and DNA molecules to be imaged and tracked, affording measurement of DNA unwinding and translocation at single-molecule resolution.

  10. Human genome sequencing with direct x-ray holographic imaging. Final report

    SciTech Connect

    Rhodes, C.K.

    1993-06-08

    Direct holographic imaging of biological materials is widely applicable to the study of the structure, properties and action of genetic material. This particular application involves the sequencing of the human genome where prospective genomic imaging technology is composed of three subtechnologies, name an x-ray holographic camera, suitable chemistry and enzymology for the preparation of tagged DNA samples, and the illuminator in the form of an x-ray laser. We report appropriate x-ray camera, embodied by the instrument developed by MCR, is available and that suitable chemical and enzymatic procedures exist for the preparation of the necessary tagged DNA strands. Concerning the future development of the x-ray illuminator. We find that a practical small scale x-ray light source is indeed feasible. This outcome requires the use of unconventional physical processes in order to achieve the necessary power-compression in the amplifying medium. The understanding of these new physical mechanisms is developing rapidly. Importantly, although the x-ray source does not currently exist, the understanding of these new physical mechanisms is developing rapidly and the research has established the basic scaling laws that will determine the properties of the x-ray illuminator. When this x-ray source becomes available, an extremely rapid and cost effective instrument for 3-D imaging of biological materials can be applied to a wide range of biological structural assays, including the base-pair sequencing of the human genome and many questions regarding its higher levels of organization.

  11. Polarization of Directly Imaged Young Giant Planets as a Probe of Mass, Rotation, and Clouds

    NASA Technical Reports Server (NTRS)

    Marley, Mark Scott; Sengupta, Sujan

    2012-01-01

    Young, hot gas giant planets at large separations from their primaries have been directly imaged around several nearby stars. More such planets will likely be detected by ongoing and new imaging surveys with instruments such as the Gemini Planet Imager (GPI). Efforts continue to model the spectra of these planets in order to constrain their masses, effective temperatures, composition, and cloud structure. One potential tool for analyzing these objects, which has received relatively less attention, is polarization. Linear polarization of gas giant exoplanets can arise from the combined influences of light scattering by atmospheric dust and a rotationally distorted shape. The oblateness of gas giant planet increases of course with rotation rate and for fixed rotation also rises with decreasing gravity. Thus young, lower mass gas giant planets with youthful inflated radii could easily have oblateness greater than that of Saturn s 10%. We find that polarizations of over 1% may easily be produced in the near-infrared in such cases. This magnitude of polarization may be measurable by GPI and other instruments. Thus if detected, polarization of a young Jupiter places constraints on the combination of its gravity, rotation rate, and degree of cloudiness. We will present results of our multiple scattering analysis coupled with a self-consistent dusty atmospheric models to demonstrate the range of polarizations that might be expected from resolved exoplanets and the range of parameter space that such observations may inform.

  12. Direct Portal Vein Thrombosis Visualization with T2*-Weighted Magnetic Resonance Imaging

    PubMed Central

    Li, Chuanming; Hu, Alice; Haacke, Mark; Wang, Jian; Zhao, Jun; Zhou, Daiquan

    2013-01-01

    BACKGROUND AND PURPOSE: To investigate the feasibility of direct magnetic resonance portal vein thrombosis (PVT) visualization with T2*-weighted imaging (T2*WI) without contrast agent. METHODS: Thirty patients with PVT were included in this study. All of them were imaged with contrast-enhanced CT (CE-CT) as well as non-contrast MRI T1, T2 and T2*WI. Imaging data was independently analyzed by two experienced radiologists. T2*WI of all PVT was compared slice-by-slice with each of the comparison sequences (T1WI, T2WI and CE-CT) on the following categories: the location, size, boundary, and conspicuity of thrombus and portal veins. RESULTS: The average score of PVT visualization in T2*WI was higher than T1WI and T2WI in location, size, boundary and conspicuity (t = 7.54 - 84.16, P<0.05), and higher than CE-CT in boundary and conspicuity (t = 3.03- 6.98, P<0.05). For portal vein visualization, there was no significant score difference in left, middle and right portal veins between CE-CT and T2*WI (t = -1.76- 1.35, P>0.05). CONCLUSIONS: Our results suggest T2*WI can characterize PVT accurately with high quality without the use of intravenous contrast agents. PMID:24046533

  13. Direct three-dimensional imaging of structure in a strongly-coupled dusty plasma

    NASA Astrophysics Data System (ADS)

    Quinn, R. A.; Goree, J.; Pieper, J. B.

    1996-11-01

    Using direct imaging of 9 μ m plastic spheres suspended in low-power Krypton discharges, we have constructed three-dimensional images showing the crystalline structure of a strongly-coupled dusty plasma. The spheres, which are highly charged and levitated by the electrode sheath, form a strongly-coupled system. A horizontal laser sheet illuminates a slice through the suspension, and a video camera views at 90^circ . Using a vertical stack of digitized images of particles in equally-spaced horizontal planes, we reconstructed the 3-D structure. We found bcc (body-centered cubic) and simple hexagonal structures coexisting in the same suspension. This coexistence is attributed to a bistability owing to an attractive potential region downstream of a charged grain in the presence of flowing ions. The probability of the system arranging in itself in the bcc or simple hexagonal phases is found to depend on the rf power that is used to sustain the discharge, and this in turn affects the particle charge and Debye length.(J. B. Pieper, J. Goree, R. A. Quinn, submitted to Phys. Rev. E) Work supported by NSF and NASA

  14. Jupiter’s Phase Variations from Cassini: A Testbed for Future Direct-imaging Missions

    NASA Astrophysics Data System (ADS)

    Mayorga, L. C.; Jackiewicz, J.; Rages, K.; West, R. A.; Knowles, B.; Lewis, N.; Marley, M. S.

    2016-12-01

    We present empirical phase curves of Jupiter from ∼0° to 140° as measured in multiple optical bandpasses by Cassini/Imaging Science Subsystem (ISS) during the Millennium flyby of Jupiter in late 2000 to early 2001. Phase curves are of interest for studying the energy balance of Jupiter and understanding the scattering behavior of the planet as an exoplanet analog. We find that Jupiter is significantly darker at partial phases than an idealized Lambertian planet by roughly 25% and is not well fit by Jupiter-like exoplanet atmospheric models across all wavelengths. We provide analytic fits to Jupiter’s phase function in several Cassini/ISS imaging filter bandpasses. In addition, these observations show that Jupiter’s color is more variable with phase angle than predicted by models. Therefore, the color of even a near Jupiter-twin planet observed at a partial phase cannot be assumed to be comparable to that of Jupiter at full phase. We discuss how the Wide-Field Infrared Survey Telescope and other future direct-imaging missions can enhance the study of cool giants.

  15. A Space Mission Concept to Directly Image the Habitable Zone of Alpha Centauri

    NASA Astrophysics Data System (ADS)

    Bendek, E.; Belikov, R.; Males, J.; Thomas, S.; Lozi, J.

    2015-12-01

    The inner edge of Alpha Cen A&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 30cm class telescope. Contrast ratios in the order of 1010 are needed to image Earth-brightness planets. Low-resolution (5-band) spectra of all planets, will 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 Induce Amplitude Apodization coronagraph embedded in the telescope. This architecture maximizes stability and throughput. The 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 Low Order Wavefront Sensor that delivers high-precision pointing control. Finally we utilize the 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. Direct imaging of the cold jovian (?) companion GJ504b with VLT/SPHERE

    NASA Astrophysics Data System (ADS)

    Bonnefoy, Mickaël

    2015-12-01

    In 2008, the Subaru/SEEDS survey reported the direct imaging discovery of a Jovian exoplanet around the Sun-like star GJ 504. With a mass of 3-10 MJup and projected separation of 43.5 AU, this object challenges the core-accretion paradigm. This is the only known nearly mature (age ≫ 50 Myr) gas giant planet imaged so far. The very low (500 K) estimated temperature of the object makes it a benchmark for the study of the physical and chemical processes at play into the non-irradiated atmospheres of gas giants.We will present new SPHERE dual-band imaging data on the system gathered from 0.95 to 2.25 microns. The data enable to detect the companion and complete its spectral energy distribution. We use them to refine the effective temperature, surface gravity, and metallicity estimates for the object. This in turns enables to discuss the nature of the companion. We also set constraints on additional companions in the system.

  17. High resolution biomedical imaging system with direct detection of x-rays via a charge coupled device

    DOEpatents

    Atac, Muzaffer; McKay, Timothy A.

    1998-01-01

    An imaging system is provided for direct detection of x-rays from an irradiated biological tissue. The imaging system includes an energy source for emitting x-rays toward the biological tissue and a charge coupled device (CCD) located immediately adjacent the biological tissue and arranged transverse to the direction of irradiation along which the x-rays travel. The CCD directly receives and detects the x-rays after passing through the biological tissue. The CCD is divided into a matrix of cells, each of which individually stores a count of x-rays directly detected by the cell. The imaging system further includes a pattern generator electrically coupled to the CCD for reading a count from each cell. A display device is provided for displaying an image representative of the count read by the pattern generator from the cells of the CCD.

  18. High resolution biomedical imaging system with direct detection of x-rays via a charge coupled device

    DOEpatents

    Atac, M.; McKay, T.A.

    1998-04-21

    An imaging system is provided for direct detection of x-rays from an irradiated biological tissue. The imaging system includes an energy source for emitting x-rays toward the biological tissue and a charge coupled device (CCD) located immediately adjacent the biological tissue and arranged transverse to the direction of irradiation along which the x-rays travel. The CCD directly receives and detects the x-rays after passing through the biological tissue. The CCD is divided into a matrix of cells, each of which individually stores a count of x-rays directly detected by the cell. The imaging system further includes a pattern generator electrically coupled to the CCD for reading a count from each cell. A display device is provided for displaying an image representative of the count read by the pattern generator from the cells of the CCD. 13 figs.

  19. Direct magnetic resonance detection of myelin and prospects for quantitative imaging of myelin density

    PubMed Central

    Wilhelm, Michael J.; Ong, Henry H.; Tsai, Ping-Huei; Hackney, David B.; Wehrli, Felix W.

    2012-01-01

    Magnetic resonance imaging has previously demonstrated its potential for indirectly mapping myelin density, either by relaxometric detection of myelin water or magnetization transfer. Here, we investigated whether myelin can be detected and possibly quantified directly. We identified the spectrum of myelin in the spinal cord in situ as well as in myelin lipids extracted via a sucrose gradient method, and investigated its spectral properties. High-resolution solution NMR spectroscopy showed the extract composition to be in agreement with myelin’s known chemical make-up. The 400-MHz 1H spectrum of the myelin extract, at 20 °C (room temperature) and 37 °C, consists of a narrow water resonance superimposed on a broad envelope shifted ∼3.5 ppm upfield, suggestive of long-chain methylene protons. Superimposed on this signal are narrow components resulting from functional groups matching the chemical shifts of the constituents making up myelin lipids. The spectrum could be modeled as a sum of super-Lorentzians with a T2* distribution covering a wide range of values (0.008–26 ms). Overall, there was a high degree of similarity between the spectral properties of extracted myelin lipids and those found in neural tissue. The normalized difference spectrum had the hallmarks of membrane proteins, not present in the myelin extract. Using 3D radially ramp-sampled proton MRI, with a combination of adiabatic inversion and echo subtraction, the feasibility of direct myelin imaging in situ is demonstrated. Last, the integrated signal from myelin suspensions is shown, both spectroscopically and by imaging, to scale with concentration, suggesting the potential for quantitative determination of myelin density. PMID:22628562

  20. Low Dose PET Image Reconstruction with Total Variation Using Alternating Direction Method

    PubMed Central

    Yu, Xingjian; Wang, Chenye; Hu, Hongjie; Liu, Huafeng

    2016-01-01

    In this paper, a total variation (TV) minimization strategy is proposed to overcome the problem of sparse spatial resolution and large amounts of noise in low dose positron emission tomography (PET) imaging reconstruction. Two types of objective function were established based on two statistical models of measured PET data, least-square (LS) TV for the Gaussian distribution and Poisson-TV for the Poisson distribution. To efficiently obtain high quality reconstructed images, the alternating direction method (ADM) is used to solve these objective functions. As compared with the iterative shrinkage/thresholding (IST) based algorithms, the proposed ADM can make full use of the TV constraint and its convergence rate is faster. The performance of the proposed approach is validated through comparisons with the expectation-maximization (EM) method using synthetic and experimental biological data. In the comparisons, the results of both LS-TV and Poisson-TV are taken into consideration to find which models are more suitable for PET imaging, in particular low-dose PET. To evaluate the results quantitatively, we computed bias, variance, and the contrast recovery coefficient (CRC) and drew profiles of the reconstructed images produced by the different methods. The results show that both Poisson-TV and LS-TV can provide a high visual quality at a low dose level. The bias and variance of the proposed LS-TV and Poisson-TV methods are 20% to 74% less at all counting levels than those of the EM method. Poisson-TV gives the best performance in terms of high-accuracy reconstruction with the lowest bias and variance as compared to the ground truth (14.3% less bias and 21.9% less variance). In contrast, LS-TV gives the best performance in terms of the high contrast of the reconstruction with the highest CRC. PMID:28005929

  1. Direct imaging of ER calcium with targeted-esterase induced dye loading (TED).

    PubMed

    Samtleben, Samira; Jaepel, Juliane; Fecher, Caroline; Andreska, Thomas; Rehberg, Markus; Blum, Robert

    2013-05-07

    Visualization of calcium dynamics is important to understand the role of calcium in cell physiology. To examine calcium dynamics, synthetic fluorescent Ca(2+) indictors have become popular. Here we demonstrate TED (= targeted-esterase induced dye loading), a method to improve the release of Ca(2+) indicator dyes in the ER lumen of different cell types. To date, TED was used in cell lines, glial cells, and neurons in vitro. TED bases on efficient, recombinant targeting of a high carboxylesterase activity to the ER lumen using vector-constructs that express Carboxylesterases (CES). The latest TED vectors contain a core element of CES2 fused to a red fluorescent protein, thus enabling simultaneous two-color imaging. The dynamics of free calcium in the ER are imaged in one color, while the corresponding ER structure appears in red. At the beginning of the procedure, cells are transduced with a lentivirus. Subsequently, the infected cells are seeded on coverslips to finally enable live cell imaging. Then, living cells are incubated with the acetoxymethyl ester (AM-ester) form of low-affinity Ca(2+) indicators, for instance Fluo5N-AM, Mag-Fluo4-AM, or Mag-Fura2-AM. The esterase activity in the ER cleaves off hydrophobic side chains from the AM form of the Ca(2+) indicator and a hydrophilic fluorescent dye/Ca(2+) complex is formed and trapped in the ER lumen. After dye loading, the cells are analyzed at an inverted confocal laser scanning microscope. Cells are continuously perfused with Ringer-like solutions and the ER calcium dynamics are directly visualized by time-lapse imaging. Calcium release from the ER is identified by a decrease in fluorescence intensity in regions of interest, whereas the refilling of the ER calcium store produces an increase in fluorescence intensity. Finally, the change in fluorescent intensity over time is determined by calculation of ΔF/F0.

  2. WEIRD : Wide orbit Exoplanet search with InfraRed Direct imaging

    NASA Astrophysics Data System (ADS)

    Baron, Frédérique; Artigau, Etienne; Rameau, Julien; Lafrenière, David; Albert, Loic; Naud, Marie-Eve; Gagné, Jonathan; Malo, Lison; Doyon, Rene; Beichman, Charles; Delorme, Philippe; Janson, Markus

    2015-12-01

    We currently do not know what does the emission spectrum of a young 1 Jupiter-mass planet look like, as no such object has yet been directly imaged. Arguably, the most useful Jupiter-mass planet would be one that is bound to a star of known age, distance and metallicity but which has an orbit large enough (100-5000 UA) that it can be studied as an "isolated" object. We are therefore searching for the most extreme planetary systems. We are currently gathering a large dataset to try to identify such objects through deep [3.6] and [4.5] imaging from SPITZER and deep seeing-limited J (with Flamingos 2 and WIRCam) and z imaging (with GMOS-S and MegaCam) of all 181 known confirmed members of a known young association (<120 Myr) within 70pc of the Sun. Our study will reveal distant planetary companions, over the reveal distant PMCs up to 5000 AU. AU separation range, through their distinctively red z-J and [4.5]-[3.6] colors. The sensitivity limits of our combined Spitzer+ground-based program will allow detection of planets with masses as low as 1 Mjup with very low contamination rates. Here we present some preliminary results of our survey. This approach is unique in the community and will give us an overview of the architecture of the outer part of planetary systems that were never probed before. Our survey will provide benchmark young Saturn and Jupiter for imaging and spectroscopy with the JWST

  3. Real-time direct and diffraction X-ray imaging of irregular silicon wafer breakage

    PubMed Central

    Rack, Alexander; Scheel, Mario; Danilewsky, Andreas N.

    2016-01-01

    Fracture and breakage of single crystals, particularly of silicon wafers, are multi-scale problems: the crack tip starts propagating on an atomic scale with the breaking of chemical bonds, forms crack fronts through the crystal on the micrometre scale and ends macroscopically in catastrophic wafer shattering. Total wafer breakage is a severe problem for the semiconductor industry, not only during handling but also during temperature treatments, leading to million-dollar costs per annum in a device production line. Knowledge of the relevant dynamics governing perfect cleavage along the {111} or {110} faces, and of the deflection into higher indexed {hkl} faces of higher energy, is scarce due to the high velocity of the process. Imaging techniques are commonly limited to depicting only the state of a wafer before the crack and in the final state. This paper presents, for the first time, in situ high-speed crack propagation under thermal stress, imaged simultaneously in direct transmission and diffraction X-ray imaging. It shows how the propagating crack tip and the related strain field can be tracked in the phase-contrast and diffracted images, respectively. Movies with a time resolution of microseconds per frame reveal that the strain and crack tip do not propagate continuously or at a constant speed. Jumps in the crack tip position indicate pinning of the crack tip for about 1–2 ms followed by jumps faster than 2–6 m s−1, leading to a macroscopically observed average velocity of 0.028–0.055 m s−1. The presented results also give a proof of concept that the described X-ray technique is compatible with studying ultra-fast cracks up to the speed of sound. PMID:27006774

  4. Improving signal-to-noise in the direct imaging of exoplanets and circumstellar disks with MLOCI

    NASA Astrophysics Data System (ADS)

    Wahhaj, Zahed; Cieza, Lucas A.; Mawet, Dimitri; Yang, Bin; Canovas, Hector; de Boer, Jozua; Casassus, Simon; Ménard, François; Schreiber, Matthias R.; Liu, Michael C.; Biller, Beth A.; Nielsen, Eric L.; Hayward, Thomas L.

    2015-09-01

    We present a new algorithm designed to improve the signal-to-noise ratio (S/N) of point and extended source detections around bright stars in direct imaging data.One of our innovations is that we insert simulated point sources into the science images, which we then try to recover with maximum S/N. This improves the S/N of real point sources elsewhere in the field. The algorithm, based on the locally optimized combination of images (LOCI) method, is called Matched LOCI or MLOCI. We show with Gemini Planet Imager (GPI) data on HD 135344 B and Near-Infrared Coronagraphic Imager (NICI) data on several stars that the new algorithm can improve the S/N of point source detections by 30-400% over past methods. We also find no increase in false detections rates. No prior knowledge of candidate companion locations is required to use MLOCI. On the other hand, while non-blind applications may yield linear combinations of science images that seem to increase the S/N of true sources by a factor >2, they can also yield false detections at high rates. This is a potential pitfall when trying to confirm marginal detections or to redetect point sources found in previous epochs. These findings are relevant to any method where the coefficients of the linear combination are considered tunable, e.g., LOCI and principal component analysis (PCA). Thus we recommend that false detection rates be analyzed when using these techniques. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (USA), the Science and Technology Facilities Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

  5. Effect of Cu pad morphology on direct-Cu pillar formation in CMOS image sensors

    NASA Astrophysics Data System (ADS)

    Choi, Eunmi; Kim, Areum; Cui, Eunwha; Lee, Ukjae; Son, Hyung Bin; Hahn, Sang June; Pyo, Sung Gyu

    2014-09-01

    We report the feasibility of forming Ni bumps directly on Cu pads in CMOS image sensor (CIS) logic elements formed by Cu wires with diameters of less than 65 nm. The direct Ni bump process proposed in this study simplifies the fabrication process and reduces costs by eliminating the need for Al pad process. In addition, this process can secure the margin of the final layer, enabling the realization of thin camera modules. In this study, we evaluated the effect of pad annealing on the direct formation of Ni bumps over Cu pads. The results suggest that the morphology of the Cu pad varies depending on the annealing sequence, and post-passivation annealing resulted in fewer defects than pad etch annealing. The shear stress of the Ni bumps was 57.77 mgf/m2, which is six times greater than the corresponding reference value. Furthermore, we evaluated the reliability of a chip with an anisotropic conductive film (ACF) and a non-conducting paste (NCP) by using high-temperature storage (HTS), thermal cycling (TC), and wet high-temperature storage (WHTS) reliability tests. The evaluation results suggest the absence of abnormalities in all samples. [Figure not available: see fulltext.

  6. Astrophysical false positives in direct imaging for exoplanets: a white dwarf close to a rejuvenated star

    NASA Astrophysics Data System (ADS)

    Zurlo, A.; Vigan, A.; Hagelberg, J.; Desidera, S.; Chauvin, G.; Almenara, J. M.; Biazzo, K.; Bonnefoy, M.; Carson, J. C.; Covino, E.; Delorme, P.; D'Orazi, V.; Gratton, R.; Mesa, D.; Messina, S.; Moutou, C.; Segransan, D.; Turatto, M.; Udry, S.; Wildi, F.

    2013-06-01

    Context. As is the case for all techniques involved in the research for exoplanets, direct imaging has to take into account the probability of so-called astrophysical false positives, which are phenomena that mimic the signature of the objects we are seeking. Aims: In this work we present the case of a false positive found during a direct-imaging survey conducted with VLT/NACO. A promising exoplanet candidate was detected around the K2-type star HD 8049 in July 2010. Its contrast of ΔH = 7.05 at 1.57 arcsec allowed us to assume a 35 MJup companion at 50 projected AU, for the nominal system age and heliocentric distance. Methods: To check whether it was gravitationally bound to the host star, as opposed to an unrelated background object, we re-observed the system one year later and concluded a high probability of a bound system. We also used radial velocity measurements of the host star, spanning a time range of ~30 yr, to constrain the companion's mass and orbital properties, as well as to probe the host star's spectral age indicators and general spectral energy distribution. We also obtained U-band imaging with EFOSC and near-infrared spectroscopy for the companion. Results: Combining all these information we conclude that the companion of HD 8049 is a white dwarf (WD) with temperature Teff = 18 800 ± 2100 K and mass MWD = 0.56 ± 0.08 M⊙. The significant radial velocity trend combined with the imaging data indicates that the most probable orbit has a semi-major axis of about 50 AU. The discrepancy between the age indicators speaks against a bona-fide young star. The moderately high level of chromospheric activity and fast rotation, mimicking the properties of a young star, might be induced by the exchange of mass with the progenitor of the WD. This example demonstrates some of the challenges in determining accurate age estimates and identifications of faint companions. Based on observations collected at La Silla and Paranal Observatory, ESO (Chile): Programs

  7. Segmentation of a class of ophthalmological images using a directional variance operator and co-occurrence arrays

    NASA Astrophysics Data System (ADS)

    Paplinski, Andrew P.; Boyce, James F.

    1997-11-01

    The posterior capsule opacification images considered are images of the membrane encapsulating an artificial lens implanted during cataract surgery in place of the natural lens. The images are taken to monitor the state of the patient's vision after the surgery. Subsequent to the surgery, the membrane of the posterior capsule may become opacified, thus degrading the patient's vision. We discuss the methodology used and the results obtained in the segmentation of the images into transparent and opacified regions. The opacification is primarily characterized by its texture, therefore a directional standard deviation operator is applied to an image giving rise to a family of 'conjugate' images. From these images, the multi-dimensional histogram (co- occurrence) array is calculated and subsequently approximated by Gaussian distributions to form the basis for the segmentation step.

  8. Atmospheric Circulation of Brown Dwarfs and Directly Imaged Extrasolar Giant Planets

    NASA Astrophysics Data System (ADS)

    Tan, X.; Showman, A. P.

    2015-12-01

    Growing observations of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs), such as brightness variability and surface maps have provided evidence for strong atmospheric circulation on these worlds. Previous studies that serve to understand the atmospheric circulation of BDs include modeling of convection from the interior and its interactions with stably stratified atmospheres. These models show that such interactions can drive an atmospheric circulation, forming zonal jets and/or vortices. However, these models are dry, not including condensation of various chemical species. Condensation of water has previously been shown to play an important role on driving the zonal jets on four giant planets in our solar system. As such, condensation cycles of various chemical species are believed to be an important source in driving the atmospheric circulation of BDs and directly imaged EGPs. Here we present results from three-dimensional simulations for the stably stratified atmospheres of BDs and EGPs based on a general circulation model that includes the effect of a condensate cycle. Large-scale latent heating and molecular weight effect due to condensation of a single species are treated explicitly. We examine the circulation patterns caused by large-scale latent heating which results from condensation of silicate vapor in hot dwarfs and water vapor in the cold dwarfs. By varying the abundance of condensable vapor and the radiative timescale, we conclude that under normal conditions of BDs (near 1x solar abundance and relatively short radiative timescale), latent heating alone by silicate vapors is unable to drive a global circulation, leaving a quiescent atmosphere, because of the suppression to moist instability by downward transport of dry air. Models with high abundance of condensates (~5x solar) and relatively long radiative timescale, which may be the case of directly imaged EGPs, tend to maintain an active hydrological cycle and develop zonal

  9. Direct Imaging of Exoplanets around Alpha Centauri and Other Multiple Star Systems

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    We propose to demonstrate a new method to directly image planets in multiple-star systems such as Alpha Centauri. A (sun-like) star is 10 billion times brighter than an Earth-like planet that may be orbiting around it. In any real telescope, diffraction and glare from that star completely swamps the miniscule brightness of the planet, similar to how a searchlight swamps the light of a nearby firefly. Several starlight suppression systems have been demonstrated in the laboratory that can remove the leakage of light from a star down to 1010 contrast, enabling Earth-like planet detection [1], but only for single-star systems. These systems employ a combination of a coronagraph to suppress the star and a wavefront control system based on a deformable mirror (DM) to remove residual starlight (speckles) created by the imperfections of telescope optics. Removal of speckles by the DM can only occur up to the spatial frequency range of the deformable mirror (half- Nyquist). The challenge with double-star (or multi-star) systems is that the off-axis companion star lies outside the DM's control region and thus preventing the DM to remove the speckles from the off-axis star. Until now, it has been thought that removing the light of a companion star is impossible with current technology, excluding binary star systems from target lists of direct imaging missions, and so binary star systems are often excluded from target lists of direct imaging missions. Our solution uses the deformable mirror (DM) in a regime outside its nominal spatial control range, where the DM experiences what is typically a harmful side effect: aliasing. Our innovation is that we use aliasing as a feature, rather than a bug, modulating and removing speckles that are several Nyquist frequencies away from the off-axis star (while simultaneously removing the light from the on-axis star using conventional methods.) This solution potentially enables the detection of biomarkers on Earth-like planets (if they

  10. A common cis-acting sequence in the DiGeorge critical region regulates bi-directional transcription of UFD1L and CDC45L.

    PubMed

    Kunte, A; Ivey, K; Yamagishi, C; Garg, V; Yamagishi, H; Srivastava, D

    2001-10-01

    Two to three megabase deletions on chromosome 22q11 are the cytogenetic findings most commonly associated with cardiac and craniofacial defects in humans. The constellation of clinical findings associated with these deletions is termed the 22q11 deletion syndrome. We had earlier described a patient with the 22q11 deletion phenotype who was hemizygous for an atypical 20 kb microdeletion in this region. The deletion included coding regions of two genes organized head-to-head, UFD1L and CDC45L, along with an 884 bp CpG-rich intervening region. Based on this genomic organization, we hypothesized that both genes may be co-expressed and co-regulated by sequences within this region. We demonstrate that expression of both genes is enhanced in a similar pattern in precursors of structures affected by the deletion. The intergenic region is sufficient to direct transcription most strongly in the developing pharyngeal arches and limb buds of transgenic mice and can also direct bi-directional transcriptional activation in a neural crest-derived cell line. Deletion analyses revealed that a 404 bp fragment closest to UFD1L is necessary and sufficient to direct this bi-directional transcriptional activity. These results reveal the presence of a conserved regulatory region in the 22q11 deletion locus that can direct simultaneous transcription of genes involved in ubiquitin mediated protein processing (UFD1L) and cell cycle control (CDC45L).

  11. Jupiter's Phase Variations from Cassini: a testbed for future direct-imaging missions

    NASA Astrophysics Data System (ADS)

    Mayorga, Laura; Jackiewicz, Jason; Rages, Kathy; West, Robert A.; Knowles, Ben; Lewis, Nikole K.; Marley, Mark S.

    2017-01-01

    Phase curves are important for our understanding of the energy balance and scattering behavior of an exoplanet's atmosphere. In preparation for future direct-imaging missions of Jupiter-like planets, in particular WFIRST, we present phase curves of Jupiter from 0--150 degrees as measured in multiple optical bandpasses by Cassini/ISS during the Millennium flyby of Jupiter in late 2000 to early 2001. We demonstrate and confirm that Jupiter is not well represented by a Lambertian phase function and that its color is more variable with phase angle than predicted by Jupiter-like models. This indicates that a Jupiter-twin observed near quadrature may not be as straightforward to classify as a Jupiter-like planet and comment on the implications for future missions.

  12. Uniformity of LED light illumination in application to direct imaging lithography

    NASA Astrophysics Data System (ADS)

    Huang, Ting-Ming; Chang, Shenq-Tsong; Tsay, Ho-Lin; Hsu, Ming-Ying; Chen, Fong-Zhi

    2016-09-01

    Direct imaging has widely applied in lithography for a long time because of its simplicity and easy-maintenance. Although this method has limitation of lithography resolution, it is still adopted in industries. Uniformity of UV irradiance for a designed area is an important requirement. While mercury lamps were used as the light source in the early stage, LEDs have drawn a lot of attention for consideration from several aspects. Although LED has better and better performance, arrays of LEDs are required to obtain desired irradiance because of limitation of brightness for a single LED. Several effects are considered that affect the uniformity of UV irradiance such as alignment of optics, temperature of each LED, performance of each LED due to production uniformity, and pointing of LED module. Effects of these factors are considered to study the uniformity of LED Light Illumination. Numerical analysis is performed by assuming a serious of control factors to have a better understanding of each factor.

  13. Direct Imaging of Carbon Nanotube Liquid-Crystalline Phase Development in True Solutions.

    PubMed

    Kleinerman, Olga; Liberman, Lucy; Behabtu, Natnael; Pasquali, Matteo; Cohen, Yachin; Talmon, Yeshayahu

    2017-04-13

    Using direct-imaging cryogenic transmission and scanning electron microscopy, we show different stages of liquid-crystalline phase development in progressively more concentrated solutions of carbon nanotubes in chlorosulfonic acid: a dilute phase of individually dissolved carbon nanotubes; semidilute and concentrated isotropic phases; coexisting concentrated isotropic and nematic phases in local equilibrium with each other; and a fully liquid-crystalline phase. Nanometric resolution of cryogenic electron microscopy reveals carbon nanotube self-assembly into liquid-crystalline domains of several nanometers in width at very early stages. We find significant differences in carbon nanotube liquid-crystalline domain morphology as a function of the carbon nanotube aspect ratio, diameter, and degree of purity.

  14. Direct imaging of Joule heating dynamics and temperature profiling inside a carbon nanotube interconnect.

    PubMed

    Costa, Pedro M F J; Gautam, Ujjal K; Bando, Yoshio; Golberg, Dmitri

    2011-08-09

    Understanding resistive (or Joule) heating in fundamental nanoelectronic blocks, such as carbon nanotubes, remains a major challenge, particularly in regard to their structural and thermal variations during prolonged periods of electrical stress. Here we show real-time imaging of the associated effects of Joule heating in the channel of carbon nanotube interconnects. First, electrical contacts to nanotubes entirely filled with a sublimable material are made inside a transmission electron microscope. On exposure to a high current density, resistive hotspots are identified on (or near) the contact points. These later migrate and expand along the carbon nanotube, as indicated by the localized sublimation of the encapsulated material. Using the hotspot edges as markers, it is possible to estimate the internal temperature profiles of the nanotube. Simple and direct, our method provides remarkable spatial and temporal insights into the dynamics of resistive hotspots and millisecond-paced thermal variations occurring inside nanoscaled tubular interconnects.

  15. Spacer-free BODIPY fluorogens in antimicrobial peptides for direct imaging of fungal infection in human tissue

    PubMed Central

    Mendive-Tapia, Lorena; Zhao, Can; Akram, Ahsan R.; Preciado, Sara; Albericio, Fernando; Lee, Martin; Serrels, Alan; Kielland, Nicola; Read, Nick D; Lavilla, Rodolfo; Vendrell, Marc

    2016-01-01

    Fluorescent antimicrobial peptides are promising structures for in situ, real-time imaging of fungal infection. Here we report a fluorogenic probe to image Aspergillus fumigatus directly in human pulmonary tissue. We have developed a fluorogenic Trp-BODIPY amino acid with a spacer-free C-C linkage between Trp and a BODIPY fluorogen, which shows remarkable fluorescence enhancement in hydrophobic microenvironments. The incorporation of our fluorogenic amino acid in short antimicrobial peptides does not impair their selectivity for fungal cells, and enables rapid and direct fungal imaging without any washing steps. We have optimized the stability of our probes in human samples to perform multi-photon imaging of A. fumigatus in ex vivo human tissue. The incorporation of our unique BODIPY fluorogen in biologically relevant peptides will accelerate the development of novel imaging probes with high sensitivity and specificity. PMID:26956772

  16. Multi-Wave and Hybrid Imaging Techniques: A New Direction for Nondestructive Testing and Structural Health Monitoring

    PubMed Central

    Cheng, Yuhua; Deng, Yiming; Cao, Jing; Xiong, Xin; Bai, Libing; Li, Zhaojun

    2013-01-01

    In this article, the state-of-the-art multi-wave and hybrid imaging techniques in the field of nondestructive evaluation and structural health monitoring were comprehensively reviewed. A new direction for assessment and health monitoring of various structures by capitalizing the advantages of those imaging methods was discussed. Although sharing similar system configurations, the imaging physics and principles of multi-wave phenomena and hybrid imaging methods are inherently different. After a brief introduction of nondestructive evaluation (NDE), structure health monitoring (SHM) and their related challenges, several recent advances that have significantly extended imaging methods from laboratory development into practical applications were summarized, followed by conclusions and discussion on future directions. PMID:24287536

  17. Effect of condensate cycles in driving atmospheric circulation on brown dwarfs and directly imaged giant planets

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam

    2014-11-01

    Growing observations of brown dwarfs and directly imaged giant planets, including properties of the L/T transition, chemical disequilibrium, brightness variability, and surface maps have provided evidence for strong atmospheric circulation on these worlds. Previous studies that serve to understand the atmospheric circulation of brown dwarfs include modeling of convection from the interior both in a two-dimensional and global fashion, a two-layer shallow water model and a global circulation model with dry thermal perturbation at the bottom of atmosphere. These models show that interactions between the stably stratified layer and the convective interior can drive an atmospheric circulation, including zonal jets and/or vortices. However, these models are dry models, not including the condensation cycles such as silicate and iron in hot dwarfs. Condensation of water has previously been shown to play an important role on driving the zonal jets on four giant planets in our solar system. As such, condensation cycles of various species is believed to be an important source in driving the atmospheric circulation of brown dwarfs and directly imaged planets as well. Here we present results from three-dimensional simulations for the stably stratified atmospheres of brown dwarfs based on a general circulation model that includes the effect of a condensate cycle. Large-scale latent heating and molecular weight effect due to condensation of a single species are treated explicitly in our model. We examine the atmospheric circulation patterns of brown dwarfs caused by large-scale latent heating that results from condensation of silicates in hot dwarfs and water in the cold dwarfs. By varying the parameters such as abundances of condensates, effective temperature and rotational period, we explore possible configurations of the circulation, and determine implications for the observed cloud patchiness and brightness variability for brown dwarfs.

  18. A New Omni-Directional EMAT for Ultrasonic Lamb Wave Tomography Imaging of Metallic Plate Defects

    PubMed Central

    Huang, Songling; Wei, Zheng; Zhao, Wei; Wang, Shen

    2014-01-01

    This paper proposes a new omni-directional electromagnetic acoustic transducer (EMAT) for the ultrasonic Lamb wave (ULW) tomography imaging (TI) of defects in metallic plates. The proposed EMAT is composed of a permanent magnet and a coil with a contra-flexure structure. This new EMAT coil structure is used for omni-directional ULW transmission and reception and ULW TI for the first time. The theoretical background and the working principles of this EMAT are presented and analyzed. The experimental results of its use on a 3 mm thick aluminum plate indicate that the EMAT with a contra-flexure coil (CFC) can transmit and receive a pure single A0 mode ULW with a high signal-to-noise ratio (SNR). Thus, the extraction of the projection data used for ULW TI may be performed accurately. The circumferential consistency of the projection data is only slightly influenced by the distortion of the eddy current field that is induced by the new CFC with an irregular shape. When the new EMAT array is used for ULW TI using the cross-hole method and SIRT arithmetic, a desirable imaging quality can be achieved, and the estimated size of an artificial corrosion defect agreed well with its actual value. The relation between the reconstruction resolution and the number of the new EMATs used is analyzed. More TI experiments are carried out when the aluminum plate defect is in two different locations relative to the EMAT array, for the further investigation of the performances of the new EMATs. PMID:24561398

  19. SPOTS: Search for Planets Orbiting Two Stars A Direct Imaging Survey for Circumbinary Planets

    NASA Astrophysics Data System (ADS)

    Thalmann, C.; Desidera, S.; Bergfors, C.; Boccaletti, A.; Bonavita, M.; Carson, J. C.; Feldt, M.; Goto, M.; Henning, T.; Janson, M.; Mordasini, C.

    2013-09-01

    Over the last decade, a vast amount of effort has been poured into gaining a better understanding of the fre- quency and diversity of extrasolar planets. Yet, most of these studies focus on single stars, leaving the population of planets in multiple systems poorly explored. This investigational gap persists despite the fact that both theoretical and observational evidence suggest that such systems represent a significant fraction of the overall planet population. With SPOTS, the Search for Planets Orbiting Two Stars, we are now carrying out the first direct imaging campaign dedicated to circumbinary planets. Our long-term goals are to survey 66 spectroscopic binaries in H-band with VLT NaCo and VLT SPHERE over the course of 4-5 years. This will establish first constraints on the wide-orbit circumbinary planet population, and may yield the spectacular first image of a bona fide circumbinary planet. Here we report on the results of the first two years of the SPOTS survey, as well as on our ongoing observation program.

  20. Direct spectral imaging of plasmonic nanohole arrays for real-time sensing.

    PubMed

    Seiler, Spencer T; Rich, Isabel S; Lindquist, Nathan C

    2016-05-06

    Plasmon-enhanced optical transmission through arrays of nano-structured holes has led to the development of a new generation of optical sensors. In this paper, to dramatically simplify the standard optical setups of these sensors, we position the nanoholes, an LED illumination source and a spacer layer directly on top of a CMOS imager chip. Transmitted light diffracts from the nanohole array, spreading into a spectrum over the space of a millimeter to land on the imager as a full spectrum. Our chip is used as a sensor in both a liquid and a gas environment. The spectrum is monitored in real-time and the plasmon-enhanced transmission peaks shift upon exposure to different concentrations of glycerol-in-water solutions or ethanol vapors in nitrogen. While liquids provide good refractive index contrast for sensing, to enhance sensitivity to solvent vapors, we filled the nanoholes with solvatochromic dyes. This on-chip solution circumvents the bulky components (e.g. microscopes, coupling optics, and spectrometers) needed for traditional plasmonic sensing setups, uses the nanohole array as both the sensing surface and a diffraction grating, and maintains good sensitivity. Finally, we show simultaneous sensing from two side-by-side locations, demonstrating potential for multiplexing and lab on a chip integration.

  1. Direct Imaging and Interferometric Followup of Our Closest Low-Mass Stellar Neighbors

    NASA Astrophysics Data System (ADS)

    Girard, J.

    2014-04-01

    Luhman 16 AB is a L/T brown dwarf binary system at only 2 pc from us. Discovered a year ago thanks to WISE (Luhman 2013), it has already been extensively studied (spectral types, variability, cloud map, etc. a total of 8 refereed publications). In this contribution I tackle the possibility of following up such target with the state of the art high contrast imaging and interferometric techniques. Though the system isn't young, it is so close and its components have mild effective temperature that we can probe for planetary-mass companions down to solar system scales. I will present results from our deep NACO L'-band search and expose our strategy and attempt with VLTI/PIONIER H-band (four 8m telescopes) to reach the habitable zone (~0.005 AU) and provide direct upper limits on the diameter of both Luhman A and B. Finally I will discuss the possibility of tackling such objects with the coming generation of high contrast imagers.

  2. Flight demonstration of a milliarcsecond pointing system for direct exoplanet imaging.

    PubMed

    Mendillo, Christopher B; Chakrabarti, Supriya; Cook, Timothy A; Hicks, Brian A; Lane, Benjamin F

    2012-10-10

    We present flight results from the optical pointing control system onboard the Planetary Imaging Concept Testbed Using a Rocket Experiment (PICTURE) sounding rocket. PICTURE (NASA mission number: 36.225 UG) was launched on 8 October 2011, from White Sands Missile Range. It attempted to directly image the exozodiacal dust disk of ϵ Eridani (K2V, 3.22 pc) down to an inner radius of 1.5 AU using a visible nulling coronagraph. The rocket attitude control system (ACS) provided 627 milliarcsecond (mas) RMS body pointing (~2'' peak-to-valley). The PICTURE fine pointing system (FPS) successfully stabilized the telescope beam to 5.1 mas (0.02λ/D) RMS using an angle tracker camera and fast steering mirror. This level of pointing stability is comparable to that of the Hubble Space Telescope. We present the hardware design of the FPS, a description of the limiting noise sources and a power spectral density analysis of the FPS and rocket ACS in-flight performance.

  3. Direct imaging of a two-dimensional silica glass on graphene.

    PubMed

    Huang, Pinshane Y; Kurasch, Simon; Srivastava, Anchal; Skakalova, Viera; Kotakoski, Jani; Krasheninnikov, Arkady V; Hovden, Robert; Mao, Qingyun; Meyer, Jannik C; Smet, Jurgen; Muller, David A; Kaiser, Ute

    2012-02-08

    Large-area graphene substrates provide a promising lab bench for synthesizing, manipulating, and characterizing low-dimensional materials, opening the door to high-resolution analyses of novel structures, such as two-dimensional (2D) glasses, that cannot be exfoliated and may not occur naturally. Here, we report the accidental discovery of a 2D silica glass supported on graphene. The 2D nature of this material enables the first atomic resolution transmission electron microscopy of a glass, producing images that strikingly resemble Zachariasen's original 1932 cartoon models of 2D continuous random network glasses. Atomic-resolution electron spectroscopy identifies the glass as SiO(2) formed from a bilayer of (SiO(4))(2-) tetrahedra and without detectable covalent bonding to the graphene. From these images, we directly obtain ring statistics and pair distribution functions that span short-, medium-, and long-range order. Ab initio calculations indicate that van der Waals interactions with graphene energetically stabilizes the 2D structure with respect to bulk SiO(2). These results demonstrate a new class of 2D glasses that can be applied in layered graphene devices and studied at the atomic scale.

  4. Mapping the crop row direction by using Formosat-2 panchromatic images.

    NASA Astrophysics Data System (ADS)

    Marais-Sicre, C.; Baup, F.; Fieuzal, R.

    2012-04-01

    The detection of crop row direction is a key factor for landscape analyses from satellite images. In optical and microwave frequency domains, Kimes and al, 1983 and Ulaby and al, 1984 shown the strong impact of the crop row orientation on the optical reflectance (Bidirectional reflectance distribution function) and on the radar backscattering coefficient (from L to X band). Consequently, it is particularly important to consider this parameter for remote sensing analyses but also in the physical and empirical approaches intended to the estimation of biophysical parameters (vegetation biomass, humidity, soil moisture content, tillage, runoff, erosion…) at the agricultural field scale. The studied area is located near Toulouse (South-west of France) in a region of alluvial plains and hills, which are mostly mixed farming and governed by a temperate climate with an annual rainfall of about 600mm per year. The region is composed of a wide variety of irrigated and non-irrigated crops (wheat, sunflower, corn, hemp…). Agricultural fields are strongly contrasted in terms of geometric forms, surface area (from 1ha to 50ha), type of soils, slopes... The remote sensing analyses are based on a time series of 13 panchromatic Formosat-2 images, acquired with a spatial resolution of 2 meters, and processed with a TOA (Top of Atmosphere) radiometric correction. Ground data are collected, the closest of satellite acquisitions, over 232 plots during the MCM'10 experiment (Multispectral Crop Monitoring, http://www.cesbio.ups-tlse.fr/us/mcm.html) conducted by the CESBIO laboratory in 2010. The proposed approach consists in estimating row direction, by using directional convolution filters and operators of mathematical morphology. First of all, one date capabilities is discussed, improved by multi-temporal analyses. Then, an original method is proposed for extrapolating the estimated row direction to the scene (over the Formosat-2 swath). Best results, obtained for multi

  5. Skin cancer texture analysis of OCT images based on Haralick, fractal dimension and the complex directional field features

    NASA Astrophysics Data System (ADS)

    Raupov, Dmitry S.; Myakinin, Oleg O.; Bratchenko, Ivan A.; Kornilin, Dmitry V.; Zakharov, Valery P.; Khramov, Alexander G.

    2016-04-01

    Optical coherence tomography (OCT) is usually employed for the measurement of tumor topology, which reflects structural changes of a tissue. We investigated the possibility of OCT in detecting changes using a computer texture analysis method based on Haralick texture features, fractal dimension and the complex directional field method from different tissues. These features were used to identify special spatial characteristics, which differ healthy tissue from various skin cancers in cross-section OCT images (B-scans). Speckle reduction is an important pre-processing stage for OCT image processing. In this paper, an interval type-II fuzzy anisotropic diffusion algorithm for speckle noise reduction in OCT images was used. The Haralick texture feature set includes contrast, correlation, energy, and homogeneity evaluated in different directions. A box-counting method is applied to compute fractal dimension of investigated tissues. Additionally, we used the complex directional field calculated by the local gradient methodology to increase of the assessment quality of the diagnosis method. The complex directional field (as well as the "classical" directional field) can help describe an image as set of directions. Considering to a fact that malignant tissue grows anisotropically, some principal grooves may be observed on dermoscopic images, which mean possible existence of principal directions on OCT images. Our results suggest that described texture features may provide useful information to differentiate pathological from healthy patients. The problem of recognition melanoma from nevi is decided in this work due to the big quantity of experimental data (143 OCT-images include tumors as Basal Cell Carcinoma (BCC), Malignant Melanoma (MM) and Nevi). We have sensitivity about 90% and specificity about 85%. Further research is warranted to determine how this approach may be used to select the regions of interest automatically.

  6. The International Deep Planet Survey. II. The frequency of directly imaged giant exoplanets with stellar mass

    NASA Astrophysics Data System (ADS)

    Galicher, R.; Marois, C.; Macintosh, B.; Zuckerman, B.; Barman, T.; Konopacky, Q.; Song, I.; Patience, J.; Lafrenière, D.; Doyon, R.; Nielsen, E. L.

    2016-10-01

    Context. Radial velocity and transit methods are effective for the study of short orbital period exoplanets but they hardly probe objects at large separations for which direct imaging can be used. Aims: We carried out the international deep planet survey of 292 young nearby stars to search for giant exoplanets and determine their frequency. Methods: We developed a pipeline for a uniform processing of all the data that we have recorded with NIRC2/Keck II, NIRI/Gemini North, NICI/Gemini South, and NACO/VLT for 14 yr. The pipeline first applies cosmetic corrections and then reduces the speckle intensity to enhance the contrast in the images. Results: The main result of the international deep planet survey is the discovery of the HR 8799 exoplanets. We also detected 59 visual multiple systems including 16 new binary stars and 2 new triple stellar systems, as well as 2279 point-like sources. We used Monte Carlo simulations and the Bayesian theorem to determine that 1.05+2.80-0.70% of stars harbor at least one giant planet between 0.5 and 14 MJ and between 20 and 300 AU. This result is obtained assuming uniform distributions of planet masses and semi-major axes. If we consider power law distributions as measured for close-in planets instead, the derived frequency is 2.30+5.95-1.55%, recalling the strong impact of assumptions on Monte Carlo output distributions. We also find no evidence that the derived frequency depends on the mass of the hosting star, whereas it does for close-in planets. Conclusions: The international deep planet survey provides a database of confirmed background sources that may be useful for other exoplanet direct imaging surveys. It also puts new constraints on the number of stars with at least one giant planet reducing by a factor of two the frequencies derived by almost all previous works. Tables 11-15 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  7. Direct imaging of Pt single atoms adsorbed on TiO2 (110) surfaces.

    PubMed

    Chang, Teng-Yuan; Tanaka, Yusuke; Ishikawa, Ryo; Toyoura, Kazuaki; Matsunaga, Katsuyuki; Ikuhara, Yuichi; Shibata, Naoya

    2014-01-08

    Noble metal nanoparticles (e.g., gold and platinum) supported on TiO2 surfaces are utilized in many technological applications such as heterogeneous catalysts. To fully understand their enhanced catalytic activity, it is essential to unravel the interfacial interaction between the metal atoms and TiO2 surfaces at the level of atomic dimensions. However, it has been extremely difficult to directly characterize the atomic-scale structures that result when individual metal atoms are adsorbed on the TiO2 surfaces. Here, we show direct atomic-resolution images of individual Pt atoms adsorbed on TiO2 (110) surfaces using aberration-corrected scanning transmission electron microscopy. Subangstrom spatial resolution enables us to identify five different Pt atom adsorption sites on the TiO2 (110) surface. Combining this with systematic density functional theory calculations reveals that the most favorable Pt adsorption sites are on vacancy sites of basal oxygen atoms that are located in subsurface positions relative to the top surface bridging oxygen atoms.

  8. Direct imaging of nanoscale dissolution of dicalcium phosphate dihydrate by an organic ligand: concentration matters.

    PubMed

    Qin, Lihong; Zhang, Wenjun; Lu, Jianwei; Stack, Andrew G; Wang, Lijun

    2013-01-01

    Unraveling the kinetics and mechanisms of sparingly soluble calcium orthophosphate (Ca-P) dissolution in the presence of organic acids at microscopic levels is important for an improved understanding in determining the effectiveness of organic acids present in most rhizosphere environments. Herein, we use in situ atomic force microscopy (AFM) coupled with a fluid reaction cell to image dissolution on the (010) face of brushite, CaHPO4 · 2H2O, in citrate-bearing solutions over a broad concentration range. We directly measure the dependence of molecular step retreat rate on citrate concentration at various pH values and ionic strengths, relevant to soil solution conditions. We find that low concentrations of citrate (10-100 μM) induced a reduction in step retreat rates along both the [100]Cc and [101]Cc directions. However, at higher concentrations (exceeding 0.1 mM), this inhibitory effect was reversed with step retreat speeds increasing rapidly. These results demonstrate that the concentration-dependent modulation of nanoscale Ca-P phase dissolution by citrate may be applied to analyze the controversial role of organic acids in enhancing Ca-P mineral dissolution in a more complex rhizosphere environment. These in situ observations may contribute to resolving the previously unrecognized interactions of root exudates (low molecular weight organic acids) and sparingly soluble Ca-P minerals.

  9. Metabolic Profiling Directly from the Petri Dish Using Nanospray Desorption Electrospray Ionization Imaging Mass Spectrometry

    SciTech Connect

    Watrous, Jeramie D.; Roach, Patrick J.; Heath, Brandi S.; Alexandrov, Theodore; Laskin, Julia; Dorrestein, Pieter C.

    2013-11-05

    Understanding molecular interaction pathways in complex biological systems constitutes a treasure trove of knowledge that might facilitate the specific, chemical manipulation of the countless microbiological systems that occur throughout our world. However, there is a lack of methodologies that allow the direct investigation of chemical gradients and interactions in living biological systems, in real time. Here, we report the use of nanospray desorption electrospray ionization (nanoDESI) imaging mass spectrometry for in vivo metabolic profiling of living bacterial colonies directly from the Petri dish with absolutely no sample preparation needed. Using this technique, we investigated single colonies of Shewanella oneidensis MR-1, Bacillus subtilis 3610, and Streptomyces coelicolor A3(2) as well as a mixed biofilm of S. oneidensis MR-1 and B. subtilis 3610. Data from B. subtilis 3610 and S. coelicolor A3(2) provided a means of validation for the method while data from S. oneidensis MR-1 and the mixed biofilm showed a wide range of compounds that this bacterium uses for the dissimilatory reduction of extracellular metal oxides, including riboflavin, iron-bound heme and heme biosynthetic intermediates, and the siderophore putrebactin.

  10. Direct Imaging of Natural Fractures and Stress Compartments Stimulated by Hydraulic Fracturing

    NASA Astrophysics Data System (ADS)

    Lacazette, A.; Vermilye, J. M.

    2014-12-01

    This contribution will present results from passive seismic studies of hydraulic fracture treatments in North American and Asian basins. One of the key data types is a comparatively new surface-based seismic imaging product - "Tomographic Fracture Images®" (TFI®). The procedure is an extension of Seismic Emission Tomography (SET), which is well-established and widely used. Conventional microseismic results - microearthquake hypocenter locations, magnitudes, and focal mechanism solutions - are also obtained from the data via a branch of the processing workflow. TFI is accomplished by summing the individual time steps in a multidimensional SET hypervolume over extended periods of time, such as an entire frac stage. The dimensions of a SET hypervolume are the X, Y, and Z coordinates of the voxels, the time step (typically on the order of 100 milliseconds), and the seismic activity value. The resulting summed volume is skeletonized to produce images of the main fracture surfaces, which are known to occupy the maximum activity surfaces of the high activity clouds from theory, field studies, and experiments. The orientation vs. area of the resulting TFIs can be analyzed in detail and compared with independent data sets such as volumetric structural attributes from reflection seismic data and borehole fracture data. We find that the primary effect of hydraulic fracturing is to stimulate preexisting natural fracture networks and faults. The combination of TFIs with hypocenter distributions and microearthquake focal mechanisms provides detailed information on subsurface stress compartmentalization. Faults are directly imaged which allows discrimination of fault planes from auxiliary planes of focal mechanism solutions. Examples that will be shown include simultaneous movement on a thrust fault and tear fault and examples of radically different stress compartments (e.g. extensional vs. wrench faulting) stimulated during a single hydraulic fracture treatment. The figure

  11. Optical imaging of human cone photoreceptors directly following the capture of light.

    PubMed

    Bedggood, Phillip; Metha, Andrew

    2013-01-01

    Capture of light in the photoreceptor outer segment initiates a cascade of chemical events that inhibit neurotransmitter release, ultimately resulting in vision. The massed response of the photoreceptor population can be measured non-invasively by electrical recordings, but responses from individual cells cannot be measured without dissecting the retina. Here we used optical imaging to observe individual human cones in the living eye as they underwent bleaching of photopigment and associated phototransduction. The retina was simultaneously stimulated and observed with high intensity visible light at 1 kHz, using adaptive optics. There was marked variability between individual cones in both photosensitivity and pigment optical density, challenging the conventional assumption that photoreceptors act as identical subunits (coefficient of variation in rate of photoisomerization = 23%). There was also a pronounced inverse correlation between these two parameters (p<10(-7)); the temporal evolution of image statistics revealed this to be a dynamic relationship, with cone waveguiding efficiency beginning a dramatic increase within 3 ms of light onset. Beginning as early as 2 ms after light onset and including half of cells by ∼7 ms, cone intensity showed reversals characteristic of interference phenomena, with greater delays in reversal corresponding to cones with more photopigment (p<10(-3)). The timing of these changes is argued to best correspond with either the cessation of dark current, or to related events such as changes in intracellular cGMP. Cone intensity also showed fluctuations of high frequency (332±25 Hz) and low amplitude (3.0±0.85%). Other groups have shown similar fluctuations that were directly evoked by light; if this corresponds to the same phenomenon, we propose that the amplitude of fluctuation may be increased by the use of a bright flash followed by a brief pause, to allow recovery of cone circulating current.

  12. Recording multiple spatially-heterodyned direct to digital holograms in one digital image

    DOEpatents

    Hanson, Gregory R.; Bingham, Philip R.

    2008-03-25

    Systems and methods are described for recording multiple spatially-heterodyned direct to digital holograms in one digital image. A method includes digitally recording, at a first reference beam-object beam angle, a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram to sit on top of a first spatial-heterodyne carrier frequency defined by the first reference beam-object beam angle; digitally recording, at a second reference beam-object beam angle, a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram to sit on top of a second spatial-heterodyne carrier frequency defined by the second reference beam-object beam angle; applying a first digital filter to cut off signals around the first original origin and define a first result; performing a first inverse Fourier transform on the first result; applying a second digital filter to cut off signals around the second original origin and define a second result; and performing a second inverse Fourier transform on the second result, wherein the first reference beam-object beam angle is not equal to the second reference beam-object beam angle and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

  13. Direct Imaging of Hippocampal Epileptiform Calcium Motifs Following Kainic Acid Administration in Freely Behaving Mice

    PubMed Central

    Berdyyeva, Tamara K.; Frady, E. Paxon; Nassi, Jonathan J.; Aluisio, Leah; Cherkas, Yauheniya; Otte, Stephani; Wyatt, Ryan M.; Dugovic, Christine; Ghosh, Kunal K.; Schnitzer, Mark J.; Lovenberg, Timothy; Bonaventure, Pascal

    2016-01-01

    Prolonged exposure to abnormally high calcium concentrations is thought to be a core mechanism underlying hippocampal damage in epileptic patients; however, no prior study has characterized calcium activity during seizures in the live, intact hippocampus. We have directly investigated this possibility by combining whole-brain electroencephalographic (EEG) measurements with microendoscopic calcium imaging of pyramidal cells in the CA1 hippocampal region of freely behaving mice treated with the pro-convulsant kainic acid (KA). We observed that KA administration led to systematic patterns of epileptiform calcium activity: a series of large-scale, intensifying flashes of increased calcium fluorescence concurrent with a cluster of low-amplitude EEG waveforms. This was accompanied by a steady increase in cellular calcium levels (>5 fold increase relative to the baseline), followed by an intense spreading calcium wave characterized by a 218% increase in global mean intensity of calcium fluorescence (n = 8, range [114–349%], p < 10−4; t-test). The wave had no consistent EEG phenotype and occurred before the onset of motor convulsions. Similar changes in calcium activity were also observed in animals treated with 2 different proconvulsant agents, N-methyl-D-aspartate (NMDA) and pentylenetetrazol (PTZ), suggesting the measured changes in calcium dynamics are a signature of seizure activity rather than a KA-specific pathology. Additionally, despite reducing the behavioral severity of KA-induced seizures, the anticonvulsant drug valproate (VA, 300 mg/kg) did not modify the observed abnormalities in calcium dynamics. These results confirm the presence of pathological calcium activity preceding convulsive motor seizures and support calcium as a candidate signaling molecule in a pathway connecting seizures to subsequent cellular damage. Integrating in vivo calcium imaging with traditional assessment of seizures could potentially increase translatability of pharmacological

  14. Complete fourier direct magnetic resonance imaging (CFD-MRI) for diffusion MRI

    PubMed Central

    Özcan, Alpay

    2013-01-01

    The foundation for an accurate and unifying Fourier-based theory of diffusion weighted magnetic resonance imaging (DW–MRI) is constructed by carefully re-examining the first principles of DW–MRI signal formation and deriving its mathematical model from scratch. The derivations are specifically obtained for DW–MRI signal by including all of its elements (e.g., imaging gradients) using complex values. Particle methods are utilized in contrast to conventional partial differential equations approach. The signal is shown to be the Fourier transform of the joint distribution of number of the magnetic moments (at a given location at the initial time) and magnetic moment displacement integrals. In effect, the k-space is augmented by three more dimensions, corresponding to the frequency variables dual to displacement integral vectors. The joint distribution function is recovered by applying the Fourier transform to the complete high-dimensional data set. In the process, to obtain a physically meaningful real valued distribution function, phase corrections are applied for the re-establishment of Hermitian symmetry in the signal. Consequently, the method is fully unconstrained and directly presents the distribution of displacement integrals without any assumptions such as symmetry or Markovian property. The joint distribution function is visualized with isosurfaces, which describe the displacement integrals, overlaid on the distribution map of the number of magnetic moments with low mobility. The model provides an accurate description of the molecular motion measurements via DW–MRI. The improvement of the characterization of tissue microstructure leads to a better localization, detection and assessment of biological properties such as white matter integrity. The results are demonstrated on the experimental data obtained from an ex vivo baboon brain. PMID:23596401

  15. Effects of latent heating on driving atmospheric circulation of brown dwarfs and directly imaged giant planets

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam P.

    2015-12-01

    Growing observations of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs), such as brightness variability and surface maps have provided evidence for strong atmospheric circulation on these worlds. Previous studies that serve to understand the atmospheric circulation of BDs include modeling of convection from the interior and its interactions with stably stratified atmospheres. These models show that such interactions can drive an atmospheric circulation, forming zonal jets and/or vortices. However, these models are dry, not including condensation of various chemical species. Latent heating from condensation of water has previously been shown to play an important role on driving the zonal jets on four giant planets in our solar system. As such, condensation cycles of various chemical species are believed to be an important source in driving the atmospheric circulation of BDs and directly imaged EGPs. Here we present results from three-dimensional simulations for the atmospheres of BDs and EGPs based on a general circulation model that includes the effect of a condensate cycle. Large-scale latent heating and molecular weight effect due to condensation of a single species are treated explicitly. We examine the circulation patterns caused by large-scale latent heating which results from condensation of silicate vapor in hot dwarfs and water vapor in the cold dwarfs. By varying the abundance of condensable vapor and the radiative timescale, we conclude that under normal atmospheric conditions of BDs (hot and thus with relatively short radiative timescale), latent heating alone by silicate vapor is unable to drive a global circulation, leaving a quiescent atmosphere, because of the suppression to moist instability by downward transport of dry air. Models with relatively long radiative timescale, which may be the case for cooler bodies, tend to maintain an active hydrological cycle and develop zonal jets. Once condensation happens, storms driven by

  16. Direct imaging of enhanced current collection on grain boundaries of Cu(In,Ga)Se{sub 2} solar cells

    SciTech Connect

    Kim, JunHo; Kim, SeongYeon; Jiang, Chun-Sheng; Ramanathan, Kannan; Al-Jassim, Mowafak M.

    2014-02-10

    We report on direct imaging of current collection by performing conductive atomic force microscopy (C-AFM) measurement on a complete Cu(In,Ga)Se{sub 2} solar cell. The localized current was imaged by milling away the top conductive layer of the device by repeated C-AFM scans. The result exhibits enhanced photocurrent collection on grain boundaries (GBs) of CIGS films, consistent with the argument for electric-field-assisted carrier collection on the GBs.

  17. DIAGNOSTIC IMAGING IN A DIRECT-ACCESS SPORTS PHYSICAL THERAPY CLINIC: A 2-YEAR RETROSPECTIVE PRACTICE ANALYSIS

    PubMed Central

    Dedekam, Erik A.; Johnson, Michael R.; Dembowski, Scott C.; Westrick, Richard B.; Goss, Donald L.

    2016-01-01

    Background While advanced diagnostic imaging is a large contributor to the growth in health care costs, direct-access to physical therapy is associated with decreased rates of diagnostic imaging. No study has systematically evaluated with evidence-based criteria the appropriateness of advanced diagnostic imaging, including magnetic resonance imaging (MRI), when ordered by physical therapists. The primary purpose of this study was to describe the appropriateness of magnetic resonance imaging (MRI) or magnetic resonance arthrogram (MRA) exams ordered by physical therapists in a direct-access sports physical therapy clinic. Study Design Retrospective observational study of practice. Hypothesis Greater than 80% of advanced diagnostic imaging orders would have an American College of Radiology (ACR) Appropriateness Criteria rating of greater than 6, indicating an imaging order that is usually appropriate. Methods A 2-year retrospective analysis identified 108 MRI/MRA examination orders from four physical therapists. A board-certified radiologist determined the appropriateness of each order based on ACR appropriateness criteria. The principal investigator and co-investigator radiologist assessed agreement between the clinical diagnosis and MRI/surgical findings. Results Knee (31%) and shoulder (25%) injuries were the most common. Overall, 55% of injuries were acute. The mean ACR rating was 7.7; scores from six to nine have been considered appropriate orders and higher ratings are better. The percentage of orders complying with ACR appropriateness criteria was 83.2%. Physical therapist's clinical diagnosis was confirmed by MRI/MRA findings in 64.8% of cases and was confirmed by surgical findings in 90% of cases. Conclusions Physical therapists providing musculoskeletal primary care in a direct-access sports physical therapy clinic appropriately ordered advanced diagnostic imaging in over 80% of cases. Future research should prospectively compare physical therapist

  18. Targeted molecular-genetic imaging and ligand-directed therapy in aggressive variant prostate cancer.

    PubMed

    Ferrara, Fortunato; Staquicini, Daniela I; Driessen, Wouter H P; D'Angelo, Sara; Dobroff, Andrey S; Barry, Marc; Lomo, Lesley C; Staquicini, Fernanda I; Cardó-Vila, Marina; Soghomonyan, Suren; Alauddin, Mian M; Flores, Leo G; Arap, Marco A; Lauer, Richard C; Mathew, Paul; Efstathiou, Eleni; Aparicio, Ana M; Troncoso, Patricia; Navone, Nora M; Logothetis, Christopher J; Marchiò, Serena; Gelovani, Juri G; Sidman, Richard L; Pasqualini, Renata; Arap, Wadih

    2016-10-24

    Aggressive variant prostate cancers (AVPC) are a clinically defined group of tumors of heterogeneous morphologies, characterized by poor patient survival and for which limited diagnostic and treatment options are currently available. We show that the cell surface 78-kDa glucose-regulated protein (GRP78), a receptor that binds to phage-display-selected ligands, such as the SNTRVAP motif, is a candidate target in AVPC. We report the presence and accessibility of this receptor in clinical specimens from index patients. We also demonstrate that human AVPC cells displaying GRP78 on their surface could be effectively targeted both in vitro and in vivo by SNTRVAP, which also enabled specific delivery of siRNA species to tumor xenografts in mice. Finally, we evaluated ligand-directed strategies based on SNTRVAP-displaying adeno-associated virus/phage (AAVP) particles in mice bearing MDA-PCa-118b, a patient-derived xenograft (PDX) of castration-resistant prostate cancer bone metastasis that we exploited as a model of AVPC. For theranostic (a merging of the terms therapeutic and diagnostic) studies, GRP78-targeting AAVP particles served to deliver the human Herpes simplex virus thymidine kinase type-1 (HSVtk) gene, which has a dual function as a molecular-genetic sensor/reporter and a cell suicide-inducing transgene. We observed specific and simultaneous PET imaging and treatment of tumors in this preclinical model of AVPC. Our findings demonstrate the feasibility of GPR78-targeting, ligand-directed theranostics for translational applications in AVPC.

  19. Diffusion tensor imaging of dolphin brains reveals direct auditory pathway to temporal lobe

    PubMed Central

    Berns, Gregory S.; Cook, Peter F.; Foxley, Sean; Jbabdi, Saad; Miller, Karla L.; Marino, Lori

    2015-01-01

    The brains of odontocetes (toothed whales) look grossly different from their terrestrial relatives. Because of their adaptation to the aquatic environment and their reliance on echolocation, the odontocetes' auditory system is both unique and crucial to their survival. Yet, scant data exist about the functional organization of the cetacean auditory system. A predominant hypothesis is that the primary auditory cortex lies in the suprasylvian gyrus along the vertex of the hemispheres, with this position induced by expansion of ‘associative′ regions in lateral and caudal directions. However, the precise location of the auditory cortex and its connections are still unknown. Here, we used a novel diffusion tensor imaging (DTI) sequence in archival post-mortem brains of a common dolphin (Delphinus delphis) and a pantropical dolphin (Stenella attenuata) to map their sensory and motor systems. Using thalamic parcellation based on traditionally defined regions for the primary visual (V1) and auditory cortex (A1), we found distinct regions of the thalamus connected to V1 and A1. But in addition to suprasylvian-A1, we report here, for the first time, the auditory cortex also exists in the temporal lobe, in a region near cetacean-A2 and possibly analogous to the primary auditory cortex in related terrestrial mammals (Artiodactyla). Using probabilistic tract tracing, we found a direct pathway from the inferior colliculus to the medial geniculate nucleus to the temporal lobe near the sylvian fissure. Our results demonstrate the feasibility of post-mortem DTI in archival specimens to answer basic questions in comparative neurobiology in a way that has not previously been possible and shows a link between the cetacean auditory system and those of terrestrial mammals. Given that fresh cetacean specimens are relatively rare, the ability to measure connectivity in archival specimens opens up a plethora of possibilities for investigating neuroanatomy in cetaceans and other species

  20. Targeted molecular-genetic imaging and ligand-directed therapy in aggressive variant prostate cancer

    PubMed Central

    Ferrara, Fortunato; Staquicini, Daniela I.; Driessen, Wouter H. P.; D’Angelo, Sara; Dobroff, Andrey S.; Barry, Marc; Lomo, Lesley C.; Staquicini, Fernanda I.; Cardó-Vila, Marina; Soghomonyan, Suren; Alauddin, Mian M.; Flores, Leo G.; Arap, Marco A.; Lauer, Richard C.; Mathew, Paul; Efstathiou, Eleni; Aparicio, Ana M.; Troncoso, Patricia; Navone, Nora M.; Logothetis, Christopher J.; Marchiò, Serena; Gelovani, Juri G.; Sidman, Richard L.; Pasqualini, Renata; Arap, Wadih

    2016-01-01

    Aggressive variant prostate cancers (AVPC) are a clinically defined group of tumors of heterogeneous morphologies, characterized by poor patient survival and for which limited diagnostic and treatment options are currently available. We show that the cell surface 78-kDa glucose-regulated protein (GRP78), a receptor that binds to phage-display-selected ligands, such as the SNTRVAP motif, is a candidate target in AVPC. We report the presence and accessibility of this receptor in clinical specimens from index patients. We also demonstrate that human AVPC cells displaying GRP78 on their surface could be effectively targeted both in vitro and in vivo by SNTRVAP, which also enabled specific delivery of siRNA species to tumor xenografts in mice. Finally, we evaluated ligand-directed strategies based on SNTRVAP-displaying adeno-associated virus/phage (AAVP) particles in mice bearing MDA-PCa-118b, a patient-derived xenograft (PDX) of castration-resistant prostate cancer bone metastasis that we exploited as a model of AVPC. For theranostic (a merging of the terms therapeutic and diagnostic) studies, GRP78-targeting AAVP particles served to deliver the human Herpes simplex virus thymidine kinase type-1 (HSVtk) gene, which has a dual function as a molecular-genetic sensor/reporter and a cell suicide-inducing transgene. We observed specific and simultaneous PET imaging and treatment of tumors in this preclinical model of AVPC. Our findings demonstrate the feasibility of GPR78-targeting, ligand-directed theranostics for translational applications in AVPC. PMID:27791181

  1. ⁶Li-loaded directionally sensitive anti-neutrino detector for possible geo-neutrinographic imaging applications.

    PubMed

    Tanaka, H K M; Watanabe, H

    2014-04-24

    Despite the latent and unique benefits of imaging uranium and thorium's distribution in the earth's interior, previously proposed experimental techniques used to identify the incoming geo-neutrino's direction are not applicable to practical imaging due to the high miss-identification in a neutrino's track reconstruction. After performing experimental studies and Monte-Carlo simulations, we confirmed that a significant improvement is possible in neutrino tracking identification with a (6)Li-loaded neutrino detector. For possible imaging applications, we also explore the feasibility of producing geo-neutrinographic images of gigantic magmatic reservoirs and deep structure in the mantle. We anticipate and plan to apply these newly designed detectors to radiographic imaging of the Earth's interior, monitoring of nuclear reactors, and tracking astrophysical sources of neutrinos.

  2. 6Li-loaded directionally sensitive anti-neutrino detector for possible geo-neutrinographic imaging applications

    PubMed Central

    Tanaka, H. K. M.; Watanabe, H.

    2014-01-01

    Despite the latent and unique benefits of imaging uranium and thorium's distribution in the earth's interior, previously proposed experimental techniques used to identify the incoming geo-neutrino's direction are not applicable to practical imaging due to the high miss-identification in a neutrino's track reconstruction. After performing experimental studies and Monte-Carlo simulations, we confirmed that a significant improvement is possible in neutrino tracking identification with a 6Li-loaded neutrino detector. For possible imaging applications, we also explore the feasibility of producing geo-neutrinographic images of gigantic magmatic reservoirs and deep structure in the mantle. We anticipate and plan to apply these newly designed detectors to radiographic imaging of the Earth's interior, monitoring of nuclear reactors, and tracking astrophysical sources of neutrinos. PMID:24759616

  3. Magnetic resonance image reconstruction using trained geometric directions in 2D redundant wavelets domain and non-convex optimization.

    PubMed

    Ning, Bende; Qu, Xiaobo; Guo, Di; Hu, Changwei; Chen, Zhong

    2013-11-01

    Reducing scanning time is significantly important for MRI. Compressed sensing has shown promising results by undersampling the k-space data to speed up imaging. Sparsity of an image plays an important role in compressed sensing MRI to reduce the image artifacts. Recently, the method of patch-based directional wavelets (PBDW) which trains geometric directions from undersampled data has been proposed. It has better performance in preserving image edges than conventional sparsifying transforms. However, obvious artifacts are presented in the smooth region when the data are highly undersampled. In addition, the original PBDW-based method does not hold obvious improvement for radial and fully 2D random sampling patterns. In this paper, the PBDW-based MRI reconstruction is improved from two aspects: 1) An efficient non-convex minimization algorithm is modified to enhance image quality; 2) PBDW are extended into shift-invariant discrete wavelet domain to enhance the ability of transform on sparsifying piecewise smooth image features. Numerical simulation results on vivo magnetic resonance images demonstrate that the proposed method outperforms the original PBDW in terms of removing artifacts and preserving edges.

  4. Direct Imaging of Nanoscale Dissolution of Dicalcium Phosphate Dihydrate by an Organic Ligand: Concentration Matters

    SciTech Connect

    Qin, Lihong; Zhang, Wenjun; Lu, Jianwei; Stack, Andrew G; Wang, Lijun

    2013-01-01

    Unraveling the kinetics and mechanisms of sparingly soluble calcium orthophosphate (Ca!P) dissolution in the presence of organic acids at microscopic levels is important for an improved understanding in determining the effectiveness of organic acids present in most rhizosphere environments. Herein, we use in situ atomic force microscopy (AFM) coupled with a fluid reaction cell to image dissolution on the (010) face of brushite, CaHPO4 2H2O, in citrate- bearing solutions over a broad concentration range. We directly measure the dependence of molecular step retreat rate on citrate concentration at various pH values and ionic strengths, relevant to soil solution conditions. We find that low concentrations of citrate(10!100 M)inducedareductioninstepretreatratesalongboththe[10 0]Ccand[101] Ccdirections.However,at higher concentrations (exceeding 0.1 mM), this inhibitory effect was reversed with step retreat speeds increasing rapidly. These results demonstrate that the concentration-dependent modulation of nanoscale Ca!P phase dissolution by citrate may be applied to analyze the controversial role of organic acids in enhancing Ca!P mineral dissolution in a more complex rhizosphere environment. These in situ observations may contribute to resolving the previously unrecognized interactions of root exudates (low molecular weight organic acids) and sparingly soluble Ca!P minerals.

  5. Laser direct imaging of transparent indium tin oxide electrodes using high speed stitching techniques

    NASA Astrophysics Data System (ADS)

    Cheng, Pi-Ying; Hsiao, Wen-Tse; Chung, Chien-Kai; Tseng, Shih-Feng; Liao, Ien-Chang

    2014-09-01

    To accomplish an electrode patterning in large area, we present a high speed stitching technique used in an ultraviolet laser processing system and investigate the interaction between laser beams and indium tin oxide (ITO) thin films deposited on glass substrates. After optimizing the process parameters of the laser direct imaging (LDI) for the large-area electrode patterning, the ablated lines looked like regularly fish-scale marks of about a 40 μm diameter and a 120 nm depth around the processing path. The parameters includes the laser power of 1W, the scanning speed of galvanometers of 800 mm/s, and the laser pulse repetition frequency of 50 kHz. Moreover, the resistance value of the ablated ITO thin film is larger than 200MΩ that is electrically insulated from the other regions of electrode structure. LDI technology with UV laser beam has great potential applications in patterning on wafer or sapphire substrates and patterning a conductive layer deposited on the touch panels for semiconductor and optoelectric industries, respectively.

  6. Modified deformable mirror stroke minimization control for direct imaging of exoplanets

    NASA Astrophysics Data System (ADS)

    Sun, He; Eldorado Riggs, A. J.; Kasdin, N. Jeremy; Vanderbei, Robert; Groff, Tyler

    2016-08-01

    For direct imaging of faint exoplanets, coronagraphs are widely used to suppress light and achieve a high contrast. Wavefront correction algorithms based on adaptive optics are introduced simultaneously to mitigate aberrations in the optical system. Stroke minimization is one of the primary control algorithms used for high-contrast wavefront control. This technique calculates the minimum deformation across the deformable mirrors' surface under the constraint that a targeted average contrast level in the search areas, namely the dark holes, is achieved. In this paper we present a modified linear constraint stroke minimization algorithm. Instead of using a single constraint on intensity averaged over all pixels, we constrain the electric field's real and imaginary part of each pixel in the dark holes. The new control algorithm can be written into a linear programming problem. Model reduction methods, including pixel binning and singular value decomposition (SVD), are further employed to avoid over-constraining the problem and to speed up computation. In numerical simulation, we find that the revised algorithm leads to more uniform dark holes and faster convergence.

  7. Generation of Customizable Micro-wavy Pattern through Grayscale Direct Image Lithography

    PubMed Central

    He, Ran; Wang, Shunqiang; Andrews, Geoffrey; Shi, Wentao; Liu, Yaling

    2016-01-01

    With the increasing amount of research work in surface studies, a more effective method of producing patterned microstructures is highly desired due to the geometric limitations and complex fabricating process of current techniques. This paper presents an efficient and cost-effective method to generate customizable micro-wavy pattern using direct image lithography. This method utilizes a grayscale Gaussian distribution effect to model inaccuracies inherent in the polymerization process, which are normally regarded as trivial matters or errors. The measured surface profiles and the mathematical prediction show a good agreement, demonstrating the ability of this method to generate wavy patterns with precisely controlled features. An accurate pattern can be generated with customizable parameters (wavelength, amplitude, wave shape, pattern profile, and overall dimension). This mask-free photolithography approach provides a rapid fabrication method that is capable of generating complex and non-uniform 3D wavy patterns with the wavelength ranging from 12 μm to 2100 μm and an amplitude-to-wavelength ratio as large as 300%. Microfluidic devices with pure wavy and wavy-herringbone patterns suitable for capture of circulating tumor cells are made as a demonstrative application. A completely customized microfluidic device with wavy patterns can be created within a few hours without access to clean room or commercial photolithography equipment. PMID:26902520

  8. Effects of Latent Heating on Atmospheres of Brown Dwarfs and Directly Imaged Planets

    NASA Astrophysics Data System (ADS)

    Tan, Xianyu; Showman, Adam P.

    2017-02-01

    The growing number of observations of brown dwarfs (BDs) has provided evidence for strong atmospheric circulation on these objects. Directly imaged planets share similar observations and can be viewed as low-gravity versions of BDs. Vigorous condensate cycles of chemical species in their atmospheres are inferred by observations and theoretical studies, and latent heating associated with condensation is expected to be important in shaping atmospheric circulation and influencing cloud patchiness. We present a qualitative description of the mechanisms by which condensational latent heating influences circulation, and then illustrate them using an idealized general circulation model that includes a condensation cycle of silicates with latent heating and molecular weight effect due to the rainout of the condensate. Simulations with conditions appropriate for typical T dwarfs exhibit the development of localized storms and east–west jets. The storms are spatially inhomogeneous, evolving on a timescale of hours to days and extending vertically from the condensation level to the tropopause. The fractional area of the BD covered by active storms is small. Based on a simple analytic model, we quantitatively explain the area fraction of moist plumes and show its dependence on the radiative timescale and convective available potential energy (CAPE). We predict that if latent heating dominates cloud formation processes, the fractional coverage area of clouds decreases as the spectral type goes through the L/T transition from high to lower effective temperature. This is a natural consequence of the variation of the radiative timescale and CAPE with the spectral type.

  9. Image-Directed Fine-needle Aspiration Biopsy of the Thyroid with Safety-engineered Devices

    SciTech Connect

    Sibbitt, Randy R. Palmer, Dennis J.; Sibbitt, Wilmer L. Bankhurst, Arthur D.

    2011-10-15

    Purpose: The purpose of the present study was to integrate safety-engineered devices into outpatient fine-needle aspiration (FNA) biopsy of the thyroid in an interventional radiology practice. Materials and Methods: The practice center is a tertiary referral center for image-directed FNA thyroid biopsies in difficult patients referred by the primary care physician, endocrinologist, or otolaryngologist. As a departmental quality of care and safety improvement program, we instituted integration of safety devices into our thyroid biopsy procedures and determined the effect on outcome (procedural pain, diagnostic biopsies, inadequate samples, complications, needlesticks to operator, and physician satisfaction) before institution of safety devices (54 patients) and after institution of safety device implementation (56 patients). Safety devices included a patient safety technology-the mechanical aspirating syringe (reciprocating procedure device), and a health care worker safety technology (antineedlestick safety needle). Results: FNA of thyroid could be readily performed with the safety devices. Safety-engineered devices resulted in a 49% reduction in procedural pain scores (P < 0.0001), a 56% reduction in significant pain (P < 0.002), a 21% increase in operator satisfaction (P < 0.0001), and a 5% increase in diagnostic specimens (P = 0.5). No needlesticks to health care workers or patient injuries occurred during the study. Conclusions: Safety-engineered devices to improve both patient and health care worker safety can be successfully integrated into diagnostic FNA of the thyroid while maintaining outcomes and improving safety.

  10. Histology-directed and imaging mass spectrometry: an emerging technology in ectopic calcification

    PubMed Central

    De Santis, Giorgio; Caprioli, Richard M; Quaglino, Daniela

    2015-01-01

    The present study was designed to demonstrate the potential of an optimized histology directed protein identification combined with imaging mass spectrometry technology to reveal and identify molecules associated to ectopic calcification in human tissue. As a proof of concept, mineralized and non-mineralized areas were compared within the same dermal tissue obtained from a patient affected by Pseudoxanthoma elasticum, a genetic disorder characterized by calcification only at specific sites of soft connective tissues. Data have been technically validated on a contralateral dermal tissue from the same subject and compared with those from control healthy skin. Results demonstrate that this approach 1) significantly reduces the effects generated by techniques that, disrupting tissue organization, blend data from affected and unaffected areas; 2) demonstrates that, abolishing differences due to inter-individual variability, mineralized and non-mineralized areas within the same sample have a specific protein profile and have a different distribution of molecules; 3) avoiding the bias of focusing on already known molecules, reveals a number of proteins that have been never related to the disease nor to the calcification process, thus paving the way for the selection of new molecules to be validated as pathogenic or as potential pharmacological targets. PMID:25595835

  11. Direct concentration and viability measurement of yeast in corn mash using a novel imaging cytometry method.

    PubMed

    Chan, Leo L; Lyettefi, Emily J; Pirani, Alnoor; Smith, Tim; Qiu, Jean; Lin, Bo

    2011-08-01

    Worldwide awareness of fossil-fuel depletion and global warming has been increasing over the last 30 years. Numerous countries, including the USA and Brazil, have introduced large-scale industrial fermentation facilities for bioethanol, biobutanol, or biodiesel production. Most of these biofuel facilities perform fermentation using standard baker's yeasts that ferment sugar present in corn mash, sugar cane, or other glucose media. In research and development in the biofuel industry, selection of yeast strains (for higher ethanol tolerance) and fermentation conditions (yeast concentration, temperature, pH, nutrients, etc.) can be studied to optimize fermentation performance. Yeast viability measurement is needed to identify higher ethanol-tolerant yeast strains, which may prolong the fermentation cycle and increase biofuel output. In addition, yeast concentration may be optimized to improve fermentation performance. Therefore, it is important to develop a simple method for concentration and viability measurement of fermenting yeast. In this work, we demonstrate an imaging cytometry method for concentration and viability measurements of yeast in corn mash directly from operating fermenters. It employs an automated cell counter, a dilution buffer, and staining solution from Nexcelom Bioscience to perform enumeration. The proposed method enables specific fluorescence detection of viable and nonviable yeasts, which can generate precise results for concentration and viability of yeast in corn mash. This method can provide an essential tool for research and development in the biofuel industry and may be incorporated into manufacturing to monitor yeast concentration and viability efficiently during the fermentation process.

  12. Generation of Customizable Micro-wavy Pattern through Grayscale Direct Image Lithography

    NASA Astrophysics Data System (ADS)

    He, Ran; Wang, Shunqiang; Andrews, Geoffrey; Shi, Wentao; Liu, Yaling

    2016-02-01

    With the increasing amount of research work in surface studies, a more effective method of producing patterned microstructures is highly desired due to the geometric limitations and complex fabricating process of current techniques. This paper presents an efficient and cost-effective method to generate customizable micro-wavy pattern using direct image lithography. This method utilizes a grayscale Gaussian distribution effect to model inaccuracies inherent in the polymerization process, which are normally regarded as trivial matters or errors. The measured surface profiles and the mathematical prediction show a good agreement, demonstrating the ability of this method to generate wavy patterns with precisely controlled features. An accurate pattern can be generated with customizable parameters (wavelength, amplitude, wave shape, pattern profile, and overall dimension). This mask-free photolithography approach provides a rapid fabrication method that is capable of generating complex and non-uniform 3D wavy patterns with the wavelength ranging from 12 μm to 2100 μm and an amplitude-to-wavelength ratio as large as 300%. Microfluidic devices with pure wavy and wavy-herringbone patterns suitable for capture of circulating tumor cells are made as a demonstrative application. A completely customized microfluidic device with wavy patterns can be created within a few hours without access to clean room or commercial photolithography equipment.

  13. Direct atomic imaging and density functional theory study of the Au24Pd1 cluster catalyst.

    PubMed

    Bruma, A; Negreiros, F R; Xie, S; Tsukuda, T; Johnston, R L; Fortunelli, A; Li, Z Y

    2013-10-21

    In this study we report a direct, atomic-resolution imaging of calcined Au24Pd1 clusters supported on multiwall carbon nanotubes by employing aberration-corrected scanning transmission electron microscopy. Using gold atoms as mass standards, we confirm the cluster size to be 25 ± 2, in agreement with the Au24Pd1(SR)18 precursor used in the synthesis. Concurrently, a Density-Functional/Basin-Hopping computational algorithm is employed to locate the low-energy configurations of free Au24Pd1 cluster. Cage structures surrounding a single core atom are found to be favored, with a slight preference for Pd to occupy the core site. The cluster shows a tendency toward elongated arrangements, consistent with experimental data. The degree of electron transfer from the Pd dopant to Au is quantified through a Löwdin charge analysis, suggesting that Pd may act as an electron promoter to the surrounding Au atoms when they are involved in catalytic reactions.

  14. STABILITY OF THE DIRECTLY IMAGED MULTIPLANET SYSTEM HR 8799: RESONANCE AND MASSES

    SciTech Connect

    Fabrycky, Daniel C.; Murray-Clay, Ruth A.

    2010-02-20

    A new era of directly imaged extrasolar planets has produced a three-planet system, where the masses of the planets have been estimated by untested cooling models. We point out that the nominal circular, face-on orbits of the planets lead to a dynamical instability in {approx}10{sup 5} yr, a factor of at least 100 shorter than the estimated age of the star. Reduced planetary masses produce stability only for unreasonably small planets ({approx}<2 M{sub Jup}). Relaxing the face-on assumption, but still requiring circular orbits while fitting the observed positions, makes the instability time even shorter. A promising solution is that the inner two planets have a 2:1 commensurability between their periods, and they avoid close encounters with each other through this resonance. The fact that the inner resonance has lasted until now, in spite of the perturbations of the outer planet, leads to a limit {approx}<10 M{sub Jup} on the masses unless the outer two planets are also engaged in a 2:1 mean-motion resonance. In a double resonance, which is consistent with the current data, the system could survive until now even if the planets have masses of {approx}20 M{sub Jup}. Apsidal alignment can further enhance the stability of a mean-motion resonant system. A completely different dynamical configuration, with large eccentricities and large mutual inclinations among the planets, is possible but finely tuned.

  15. LOFAR imaging of Cygnus A - direct detection of a turnover in the hotspot radio spectra

    NASA Astrophysics Data System (ADS)

    McKean, J. P.; Godfrey, L. E. H.; Vegetti, S.; Wise, M. W.; Morganti, R.; Hardcastle, M. J.; Rafferty, D.; Anderson, J.; Avruch, I. M.; Beck, R.; Bell, M. E.; van Bemmel, I.; Bentum, M. J.; Bernardi, G.; Best, P.; Blaauw, R.; Bonafede, A.; Breitling, F.; Broderick, J. W.; Brüggen, M.; Cerrigone, L.; Ciardi, B.; de Gasperin, F.; Deller, A.; Duscha, S.; Engels, D.; Falcke, H.; Fallows, R. A.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J. M.; van Haarlem, M. P.; Heald, G.; Hoeft, M.; Horst, A. J. van der; Iacobelli, M.; Intema, H.; Juette, E.; Karastergiou, A.; Kondratiev, V. I.; Koopmans, L. V. E.; Kuniyoshi, M.; Kuper, G.; van Leeuwen, J.; Maat, P.; Mann, G.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; Mulcahy, D. D.; Munk, H.; Nelles, A.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pietka, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Röttgering, H. J. A.; Rowlinson, A.; Scaife, A. M. M.; Serylak, M.; Shulevski, A.; Sluman, J.; Smirnov, O.; Steinmetz, M.; Stewart, A.; Swinbank, J.; Tagger, M.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; Vocks, C.; van Weeren, R. J.; Wucknitz, O.; Yatawatta, S.; Zarka, P.

    2016-12-01

    The low-frequency radio spectra of the hotspots within powerful radio galaxies can provide valuable information about the physical processes operating at the site of the jet termination. These processes are responsible for the dissipation of jet kinetic energy, particle acceleration, and magnetic-field generation. Here, we report new observations of the powerful radio galaxy Cygnus A using the Low Frequency Array (LOFAR) between 109 and 183 MHz, at an angular resolution of ˜3.5 arcsec. The radio emission of the lobes is found to have a complex spectral index distribution, with a spectral steepening found towards the centre of the source. For the first time, a turnover in the radio spectrum of the two main hotspots of Cygnus A has been directly observed. By combining our LOFAR imaging with data from the Very Large Array at higher frequencies, we show that the very rapid turnover in the hotspot spectra cannot be explained by a low-energy cut-off in the electron energy distribution, as has been previously suggested. Thermal (free-free) absorption or synchrotron self-absorption models are able to describe the low-frequency spectral shape of the hotspots; however, as with previous studies, we find that the implied model parameters are unlikely, and interpreting the spectra of the hotspots remains problematic.

  16. Current density imaging using directly measured harmonic Bz data in MREIT.

    PubMed

    Park, Chunjae; Kwon, Oh In

    2013-01-01

    Magnetic resonance electrical impedance tomography (MREIT) measures magnetic flux density signals through the use of a magnetic resonance imaging (MRI) in order to visualize the internal conductivity and/or current density. Understanding the reconstruction procedure for the internal current density, we directly measure the second derivative of Bz data from the measured k-space data, from which we can avoid a tedious phase unwrapping to obtain the phase signal of Bz . We determine optimal weighting factors to combine the derivatives of magnetic flux density data, [Symbol: see text](2) Bz , measured using the multi-echo train. The proposed method reconstructs the internal current density using the relationships between the induced internal current and the measured [Symbol: see text](2) Bz data. Results from a phantom experiment demonstrate that the proposed method reduces the scanning time and provides the internal current density, while suppressing the background field inhomogeneity. To implement the real experiment, we use a phantom with a saline solution including a balloon, which excludes other artifacts by any concentration gradient in the phantom.

  17. Electronic intraoral dental x-ray imaging system employing a direct sensing CCD array

    SciTech Connect

    Cox, J.D.; Langford, D.S.; Williams, D.W.

    1993-12-31

    A commercial prototype intraoral radiography system has been developed that can provide digital x-ray images for diagnosis. The system consists of an intraoral detector head, an intermediate drive electronics package, a main drive electronics package and a PC-based digital image management system. The system has the potential to replace the use of dental film in intraoral radiographic examinations. High-resolution images are acquired, then displayed on a CRT within seconds of image acquisition.

  18. Analysis of ROC on chest direct digital radiography (DR) after image processing in diagnosis of SARS

    NASA Astrophysics Data System (ADS)

    Lv, Guozheng; Lan, Rihui; Zeng, Qingsi; Zheng, Zhong

    2004-05-01

    The Severe Acute Respiratory Syndrome (SARS, also called Infectious Atypical Pneumonia), which initially broke out in late 2002, has threatened the public"s health seriously. How to confirm the patients contracting SARS becomes an urgent issue in diagnosis. This paper intends to evaluate the importance of Image Processing in the diagnosis on SARS at the early stage. Receiver Operating Characteristics (ROC) analysis has been employed in this study to compare the value of DR images in the diagnosis of SARS patients before and after image processing by Symphony Software supplied by E-Com Technology Ltd., and DR image study of 72 confirmed or suspected SARS patients were reviewed respectively. All the images taken from the studied patients were processed by Symphony. Both the original and processed images were taken into ROC analysis, based on which the ROC graph for each group of images has been produced as described below: For processed images: a = 1.9745, b = 1.4275, SA = 0.8714; For original images: a = 0.9066, b = 0.8310, SA = 0.7572; (a - intercept, b - slop, SA - Area below the curve). The result shows significant difference between the original images and processed images (P<0.01). In summary, the images processed by Symphony are superior to the original ones in detecting the opacity lesion, and increases the accuracy of SARS diagnosis.

  19. Orbital Differential Imaging: a new high-contrast post-processing technique for direct imaging of exoplanets

    NASA Astrophysics Data System (ADS)

    Males, Jared R.; Belikov, Ruslan; Bendek, Eduardo

    2015-09-01

    Current post-processing techniques in high contrast imaging depend on some source of diversity between the exoplanet signal and the residual star light at that location. The two main techniques are angular differential imaging (ADI), which makes use of parallactic sky rotation to separate planet from star light, and spectral differential imaging (SDI), which makes use of differences in the spectrum of planet and star light and the wavelength dependence of the point spread function (PSF). Here we introduce our technique for exploiting another source of diversity: orbital motion. Given repeated observations of an exoplanetary system with sufficiently short orbital periods, the motion of the planets allows us to discriminate them from the PSF. In addition to using powerful PSF subtraction algorithms, such an observing strategy enables temporal filtering. Once an orbit is determined, the planet can be "de-orbited" to further increase the signal-to-noise ratio. We call this collection of techniques Orbital Differential Imaging (ODI). Here we present the motivation for this technique, present a noise model, and present results from simulations. We believe ODI will be an enabling technique for imaging Earth-like planets in the habitable zones of Sun-like stars with dedicated space missions.

  20. Direct Seafloor Imaging of the 2012 Wharton Basin Great Strike-slip Earthquakes rupture zones

    NASA Astrophysics Data System (ADS)

    Singh, S. C.; Hananto, N.; Leclerc, F.; Wei, S.; Carton, H. D.; Tapponnier, P.; Sieh, K.; Qin, Y.

    2015-12-01

    The 2012 Wharton Basin earthquakes (Mw=8.6 and Mw=8.2) were the largest intra-plate strike-slip earthquakes ever recorded. Based on seismological and geodetic studies, different, and partly contradictory, models have been proposed for the fault geometry requiring a complex faulting mechanism with several faults, oblique to one-another. These earthquakes occurred in the Wharton Basin, which is considered to be a broad diffuse zone of intra-plate deformation with deformation taking place along re-activated N5ºE striking fracture zones, which was inconsistent with most of the seismology or geodesy based rupture models. In May-June 2015, we acquired 13 high-resolution seismic reflection profiles and more than 8500 km2 of bathymetric data to the south and southwest of the main N-S segment of the Mw=8.6 earthquake rupture and across the Mw=8.2 earthquake rupture zone. We find that the epicenter of the Mw=8.2 earthquake lies on a re-activated fracture zone, expressed as a ~50-km wide region with four N5ºE striking left-lateral sub-faults. The easternmost sub-fault is most active and might be the master fault, where the maximum deformation might be taking place. The deformation along the other sub-faults becomes more diffuse moving westward. We also imaged a set of N110ºE trending 2-km wide right-lateral shear zones, which might act as transfer zones between the re-activated N5ºE striking fracture zones, and have orientations in agreement with aftershock focal mechanisms. We suggest that the 2012 great Wharton Basin earthquakes ruptured N5ºE re-activated fractures. Furthermore, the rupture of the Mw=8.6 event proceeded in en échelon fashion with this suite of N110ºE striking shear zones connecting the re-activated fracture zone imaged in this study with another N5ºE trending re-activated fracture zone on the Ninety East Ridge. Our model explains the discrepancy between direct observations on the seafloor and distant seismological and geodetic results.

  1. Multi-band Emission Light Curves of Jupiter: Insights on Brown Dwarfs and Directly Imaged Exoplanets

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Ge, Huazhi; Orton, Glenn S.; Fletcher, Leigh N.; Sinclair, James; Fernandes, Joshua; Momary, Thomas W.; Kasaba, Yasumasa; Sato, Takao M.; Fujiyoshi, Takuya

    2016-10-01

    understanding. This work provides rich insights on the relationship between observed light curves and weather on brown dwarfs and perhaps on directly imaged exoplanets in the future.

  2. Multiple-view spectrally resolved x-ray imaging observations of polar-direct-drive implosions on OMEGA

    SciTech Connect

    Mancini, R. C.; Johns, H. M.; Joshi, T.; Mayes, D.; Nagayama, T.; Hsu, S. C.; Baumgaertel, J. A.; Cobble, J.; Krasheninnikova, N. S.; Bradley, P. A.; Hakel, P.; Murphy, T. J.; Schmitt, M. J.; Shah, R. C.; Tregillis, I. L.; Wysocki, F. J.

    2014-12-15

    We present spatially, temporally, and spectrally resolved narrow- and broad-band x-ray images of polar-direct-drive (PDD) implosions on OMEGA. These self-emission images were obtained during the deceleration phase and bang time using several multiple monochromatic x-ray imaging instruments fielded along two or three quasi-orthogonal lines-of-sight, including equatorial and polar views. The instruments recorded images based on K-shell lines from a titanium tracer located in the shell as well as continuum emission. These observations constitute the first such data obtained for PDD implosions. The image data show features attributed to laser imprinting and zero-order hydrodynamics. Equatorial-view images show a “double bun” structure that is consistent with synthetic images obtained from post-processing 2D and 3D radiation-hydrodynamic simulations of the experiment. Polar-view images show a pentagonal, petal pattern that correlates with the PDD laser illumination used on OMEGA, thus revealing a 3D aspect of PDD OMEGA implosions not previously observed. Differences are noted with respect to a PDD experiment performed at National Ignition Facility.

  3. The Direct Registration of LIDAR Point Clouds and High Resolution Image Based on Linear Feature by Introducing AN Unknown Parameter

    NASA Astrophysics Data System (ADS)

    Chunjing, Y.; Guang, G.

    2012-07-01

    The registration between optical images and point clouds is the first task when the combination of these two datasets is concerned. Due to the discrete nature of the point clouds, and the 2D-3D transformation in particular, a tie points based registration strategy which is commonly adopted in image-to-image registration is hard to be used directly in this scenario. A derived collinear equation describing the map relationship between an image point and a ground point is used as the mathematical model for registration, with the point in the LiDAR space expressed by its parametric form. such a map relation can be viewed as the mathematical model which registers the image pixels to point clouds. This model is not only suitable for a single image registration but also applicable to multiple consecutive images. We also studied scale problem in image and point clouds registration, with scale problem is defined by the optimal corresponding between the image resolution and the density of point clouds. Test dataset includes the DMC images and point clouds acquired by the Leica ALS50 II over an area in Henan Prov., China. Main contributions of the paper includes: [1] an derived collinear equation is introduced by which a ground point is expressed by its parametric form, which makes it possible to replace point feature by linear feature, hence avoiding the problem that it is almost impossible to find a point in the point clouds which is accurately corresponds to a point in the image space; [2] least square method is used to calculate the registration transformation parameters and the unknown parameter λ in the same time;[3] scale problem is analyzed semi-quantitatively and to the authors' best knowledge, it is the first time in literature that clearly defines the scale problem and carries out semi-quantitative analysis in the context of LiDAR data processing.

  4. Synchrotron imaging techniques for bone and cartilage tissue engineering: potential, current trends, and future directions.

    PubMed

    Olubamiji, Adeola Deborah; Izadifar, Zohreh; Chen, Daniel Xiongbiao

    2014-10-01

    Biomedical imaging is crucial to the success of bone/cartilage tissue engineering (TE) by providing detailed three-dimensional information on tissue-engineered scaffolds and associated bone/cartilage growth during the healing process. Synchrotron radiation (SR)-based biomedical imaging is an emerging technique for this purpose that has been drawing considerable recent attention. Due to the unique properties of synchrotron light, SR biomedical imaging can provide information that conventional X-ray imaging is not able to capture. SR biomedical imaging techniques notably differ from conventional imaging in both physics and implementation, thus varying with regard to both capability and popularity for biomedical imaging applications. In the earlier decade, synchrotron-based imaging was used in bone/cartilage TE to characterize bone/cartilage scaffolds and tissues as well as the varying degrees of success in reconstruction. However, several key issues should be addressed through research before SR biomedical imaging can be advanced to a noninvasive method for application to live animals and eventually to human patients. This review briefly presents recent developments in this area, focusing on different synchrotron-based biomedical imaging techniques and their advantages and limitations, as well as reported applications to bone and cartilage TE. Key issues and challenges are also identified and discussed along with recommendations for future research.

  5. Content-based image retrieval in radiology: current status and future directions.

    PubMed

    Akgül, Ceyhun Burak; Rubin, Daniel L; Napel, Sandy; Beaulieu, Christopher F; Greenspan, Hayit; Acar, Burak

    2011-04-01

    Diagnostic radiology requires accurate interpretation of complex signals in medical images. Content-based image retrieval (CBIR) techniques could be valuable to radiologists in assessing medical images by identifying similar images in large archives that could assist with decision support. Many advances have occurred in CBIR, and a variety of systems have appeared in nonmedical domains; however, permeation of these methods into radiology has been limited. Our goal in this review is to survey CBIR methods and systems from the perspective of application to radiology and to identify approaches developed in nonmedical applications that could be translated to radiology. Radiology images pose specific challenges compared with images in the consumer domain; they contain varied, rich, and often subtle features that need to be recognized in assessing image similarity. Radiology images also provide rich opportunities for CBIR: rich metadata about image semantics are provided by radiologists, and this information is not yet being used to its fullest advantage in CBIR systems. By integrating pixel-based and metadata-based image feature analysis, substantial advances of CBIR in medicine could ensue, with CBIR systems becoming an important tool in radiology practice.

  6. Direct observation of extrasolar planets and the development of the gemini planet imager integral field spectrograph

    NASA Astrophysics Data System (ADS)

    Chilcote, Jeffrey Kaplan

    This thesis is focused on the development and testing of a new instrument capable of finding and characterizing recently-formed Jupiter-sized planets orbiting other stars. To observe these planets, I present the design, construction and testing of the Gemini Planet Imager (GPI) Integral Field Spectrograph (IFS). GPI is a facility class instrument for the Gemini Observatory with the primary goal of directly detecting young Jovian planets. The GPI IFS utilizes an infrared transmissive lenslet array to sample a rectangular 2.7 x 2.7 arcsecond field of view and provide low-resolution spectra across five bands between 1 and 2.5 mum. The dispersing element can be replaced with a Wollaston prism to provide broadband polarimetry across the same five filter bands. The IFS construction was based at the University of California, Los Angeles in collaboration with the Universite de Montreal, Immervision and Lawrence Livermore National Laboratory. I will present performance results, from in-lab testing, of the Integral Field Spectrograph (IFS) for the Gemini Planet Imager (GPI). The IFS is a large, complex, cryogenic, optical system requiring several years of development and testing. I will present the design and integration of the mechanical and optical performance of the spectrograph optics. The IFS passed its pre-ship review in 2011 and was shipped to University of California, Santa Cruz for integration with the remaining sub-systems of GPI. The UCLA built GPI IFS was integrated with the rest of GPI and is delivering high quality spectral datacubes of GPI's coronagraphic field. Using the NIRC2 instrument located at the Keck Observatory, my collaborators and I observed the planetary companion to beta Pictoris in L' (3.5--4.1mum). Observations taken in the fall of 2009 and 2012 are used to find the location and inclination of the planet relative to the massive debris disk orbiting beta Pictoris. We find that the planet's orbit has a position angle on the sky of 211

  7. Atmospheric retrieval analysis of the directly imaged exoplanet HR 8799b

    SciTech Connect

    Lee, Jae-Min; Heng, Kevin; Irwin, Patrick G. J. E-mail: kevin.heng@csh.unibe.ch

    2013-12-01

    Directly imaged exoplanets are unexplored laboratories for the application of the spectral and temperature retrieval method, where the chemistry and composition of their atmospheres are inferred from inverse modeling of the available data. As a pilot study, we focus on the extrasolar gas giant HR 8799b, for which more than 50 data points are available. We upgrade our non-linear optimal estimation retrieval method to include a phenomenological model of clouds that requires the cloud optical depth and monodisperse particle size to be specified. Previous studies have focused on forward models with assumed values of the exoplanetary properties; there is no consensus on the best-fit values of the radius, mass, surface gravity, and effective temperature of HR 8799b. We show that cloud-free models produce reasonable fits to the data if the atmosphere is of super-solar metallicity and non-solar elemental abundances. Intermediate cloudy models with moderate values of the cloud optical depth and micron-sized particles provide an equally reasonable fit to the data and require a lower mean molecular weight. We report our best-fit values for the radius, mass, surface gravity, and effective temperature of HR 8799b. The mean molecular weight is about 3.8, while the carbon-to-oxygen ratio is about unity due to the prevalence of carbon monoxide. Our study emphasizes the need for robust claims about the nature of an exoplanetary atmosphere to be based on analyses involving both photometry and spectroscopy and inferred from beyond a few photometric data points, such as are typically reported for hot Jupiters.

  8. Direct detection of extrasolar planets with the eXtreme Adaptive Optics Planet Imager

    NASA Astrophysics Data System (ADS)

    Macintosh, B. A.; Graham, J. R.; Duchene, G.; Jones, S.; Kalas, P.; Lloyd, J.; Makidon, R. B.; Olivier, S.; Palmer, D.; Perrin, M.; Poyneer, L.; Sheinis, A.; Sivaramakrishnan, A.; Severson, S.; Sommargren, G.; Troy, M.; Wallace, J. K.

    2003-05-01

    Current radial-velocity searches for extrasolar planets, though powerful, are fundamentally constrained in the range of orbits they can access by the need for a near-complete orbital period: the largest detectable semi-major axis only grows with time to the 2/3 power. In the next several decades, radial velocity detection will barely reach planets with orbits comparable to Saturn. However, planets in our solar system exist at wider separations and dusty disks frequently exceed 100 AU, some with evidence for perturbing planets in wide orbits. To probe the 5-100 AU range different techniques are needed. Direct detection of photons emitted by extrasolar planets is one such technique, but requires contrast levels of 107-109 at near-infrared wavelengths. We have designed an adaptive optics (AO) system capable of reaching these contrasts. XAOPI, the eXtreme Adaptive Optics Planet Imager, is a proposed 4096-actuator adaptive optics system for an 8-10m telescope. It will achieve Strehl ratios >0.9, and is optimized to remove scattered light from 0.2-1 arcseconds, even light scattered by errors in a segmented primary mirror. Simulations predict that it will achieve contrast ratios of 107 -108 for target stars with R<7. Monte Carlo analysis of target samples shows that this allows detection of near-IR emission from warm extrasolar planets younger and/or more massive than Jupiter around a significant sample of target stars. We will examine the scientific rationale for, and capabilities of, this proposed instrument. This work has been supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST - 987 Portions of this work were also performed under the auspices of the U.S. Department of Energy, National Nuclear Security Administration by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

  9. Direct Imaging of an Emerging Flux Rope and a Resulting Chromospheric Jet Observed by Hinode

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Berger, T.; Title, A. M.; Tarbell, T. D.; DeRosa, M.

    2010-05-01

    Magnetic flux emergence has been traditionally observed on the disk by identifying changes in magnetograms. Observations near the limb offer an alternative perspective and allow direct imaging of emerging flux ropes. We present Hinode/SOT Ca II H observations of such an event in an equatorial coronal hole on 2007 February 9. The precursor of the event was a bundle of fine material threads that extended at an oblique angle above the chromosphere and appeared to rotate about a common axis. This bundle first slowly and then rapidly swung up, accompanied by a loop that appeared at the base of the bundle and expanded at comparable rates. During the first (slow rise) stage, the apex of the loop ascended at 16 km/s, a velocity similar to that of H-alpha arch filaments (e.g., Chou & Zirin) and of emerging flux ropes expanding into the corona as found in MHD simulations (e.g., Fan & Gibson; Martinez-Sykora). The second stage started at the onset of a GOES A5 flare and the loop expansion accelerated, reaching a velocity of 130 km/s when the loop appeared to rupture near the peak of the flare. The material bundle then swung back in a whiplike manner and developed into a collimated jet, exhibiting oscillatory transverse motions across its axis, as expected from unwinding twists. Some jet material fell back along smooth streamlines, which bypass an unseen dome and presumably a null point in the low corona, depicting an inverted-Y shape. Some of these observations resemble the model (e.g., Uchida & Shibata) of the emergence of a twisted flux rope into an open field region that leads to reconnection and formation of a jet. Some observations are, however, not predicted in previous models and we will discuss their implications.

  10. How to Directly Image a Habitable Planet Around Alpha Centauri with a 30-45 cm Space Telescope

    NASA Technical Reports Server (NTRS)

    Belikov, Ruslan; Bendek, Eduardo; Thomas, Sandrine; Males, Jared

    2015-01-01

    Several mission concepts are being studied to directly image planets around nearby stars. It is commonly thought that directly imaging a potentially habitable exoplanet around a Sun-like star requires space telescopes with apertures of at least 1m. A notable exception to this is Alpha Centauri (A and B), which is an extreme outlier among FGKM stars in terms of apparent habitable zone size: the habitable zones are approximately 3x wider in apparent size than around any other FGKM star. This enables a approximately 30-45cm visible light space telescope equipped with a modern high performance coronagraph or star shade to resolve the habitable zone at high contrast and directly image any potentially habitable planet that may exist in the system. The raw contrast requirements for such an instrument can be relaxed to 1e-8 if the mission spends 2 years collecting tens of thousands of images on the same target, enabling a factor of 500-1000 speckle suppression in post processing using a new technique called Orbital Difference Imaging (ODI). The raw light leak from both stars is controllable with a special wave front control algorithm known as Multi-Star Wave front Control (MSWC), which independently suppresses diffraction and aberrations from both stars using independent modes on the deformable mirror. This paper will present an analysis of the challenges involved with direct imaging of Alpha Centauri with a small telescope and how the above technologies are used together to solve them. We also show an example of a small coronagraphic mission concepts to take advantage of this opportunity called "ACESat: Alpha Centauri Exoplanet Satellite" submitted to NASA's small Explorer (SMEX) program in December of 2014.

  11. A comparative cost analysis of digital fundus imaging and direct fundus examination for assessment of diabetic retinopathy.

    PubMed

    Gomez-Ulla, Francisco; Alonso, Florentina; Aibar, Beatriz; Gonzalez, Francisco

    2008-11-01

    The objective of this study was to compare the cost between two procedures for fundus examination in patients with diabetes. In our setting, two alternatives for fundus examination are available for patients with diabetes. In the first alternative, a digital image is taken with a nonmydriatic fundus camera when the patient is at the endocrinology consultation, and the image is then examined by an ophthalmologist. In the second alternative, a direct fundus examination is made by an ophthalmologist. We calculated the costs of both procedures from both Public Healthcare System (PHS) and patient perspectives using the official scales to compute personnel, consumables, capital cost of equipment, travel expenses, and time loss of the patient caused by attending the consultation. The first alternative (digital fundus image) required 2.69, 0.03, and 1.62 Euros per patient for personnel, consumables, and capital cost of the equipment, respectively. A direct fundus examination was needed in 31% of patients that had an additional cost of 0.97 Euros per patient for the PHS plus 14.97 Euros per patient because of travel cost and loss of income. The second alternative (direct fundus examination) required 2.69, 0.11, and 0.33 Euros per patient for personnel, consumables, and capital cost, respectively. All patients in this second alternative had to attend a consultation that implied travel and loss of income costs. Attending a consultation represented a cost of 48.29 Euros per patient. From the PHS perspective, direct fundus examination is less costly than using digital fundus images. The higher cost of the digital fundus option is a consequence of the higher capital costs required by the equipment needed to obtain the digital image. However, from a global perspective, the digital image alternative is more convenient because the travel cost and loss of income of the patient are lower.

  12. Lipiodol: A Potential Direct Surrogate for Cone-Beam Computed Tomography Image Guidance in Radiotherapy of Liver Tumor

    SciTech Connect

    Yue Jinbo; Sun Xindong; Cai Jing; Yin Fangfang; Yin Yong; Zhu Jian; Lu Jie; Liu Tonghai; Yu Jinming; Shi Xuetao; Song Jinlong

    2012-02-01

    Purpose: To investigate the feasibility of using lipiodol as a direct surrogate for target localization using cone-beam CT (CBCT) image guidance in radiotherapy (RT) of patients with unresectable liver tumors after transarterial chemoembolization. Methods and Materials: Forty-six patients with an unresectable solitary liver tumor were enrolled for RT using active breathing control (ABC) and CBCT image guidance after transarterial chemoembolization. Each patient had pre- and posttreatment CBCT in the first 10 fractions of treatment. Lipiodol retention was evaluated using daily CBCT scans, and volume of lipiodol retention in the liver was calculated and compared between planning CT and post-RT CT. Influence of lipiodol on dosimetry was evaluated by measuring doses using an ion chamber with and without the presence of lipiodol. Margin analysis was performed on the basis of both inter- and intrafractional target localization errors. Results: Twenty-eight patients successfully completed the study. The shape and size of lipiodol retention did not vary substantially during the course of treatment. The mean Dice similarity coefficient for the lipiodol volume in pretreatment CT and that in posttreatment CT was 0.836 (range, 0.817-0.885). The maximum change (ratio of the lipiodol volume in pretreatment CT to that in posttreatment CT) was 1.045. The mean dose changes with the presence of <10 mL lipiodol were -1.44% and 0.13% for 6 MV and 15 MV, respectively. With ABC and online CBCT image guidance, clinical target volume-planning target volume margins were determined to be 2.5 mm in the mediolateral direction, 2.9 mm in the anteroposterior direction, and 4.0 mm in the craniocaudal direction. Conclusions: Lipiodol could be used as a direct surrogate for CBCT image guidance to improve the localization accuracy for RT of liver tumors. Combination of ABC and CBCT image guidance with lipiodol can potentially reduce the clinical target volume-planning target volume margin.

  13. Direct imaging of elemental distributions in tissue sections by laser ablation mass spectrometry.

    PubMed

    Shariatgorji, Mohammadreza; Nilsson, Anna; Bonta, Maximilian; Gan, Jinrui; Marklund, Niklas; Clausen, Fredrik; Källback, Patrik; Loden, Henrik; Limbeck, Andreas; Andrén, Per E

    2016-07-15

    We present a strategy for imaging of elements in biological tissues using laser ablation (LA) mass spectrometry (MS), which was compared to laser ablation inductively coupled plasma (LA-ICP) MS. Both methods were adopted for quantitative imaging of elements in mouse kidney, as well as traumatic brain injury model tissue sections. MS imaging (MSI) employing LA provides quantitative data by comparing signal abundances of sodium from tissues to those obtained by imaging quantitation calibration standards of the target element applied to adjacent control tissue sections. LA-ICP MSI provided quantitative data for several essential elements in both brain and kidney tissue sections using a dried-droplet approach. Both methods were used to image a rat model of traumatic brain injury, revealing accumulations of sodium and calcium in the impact area and its peripheral regions. LA MSI is shown to be a viable option for quantitative imaging of specific elements in biological tissue sections.

  14. Adsorption of di-l-alanine on Cu(110) investigated with scanning tunneling microscopy [rapid communication

    NASA Astrophysics Data System (ADS)

    Stensgaard, I.

    2003-11-01

    Sub-monolayer growth of a small chiral peptide, di- L-alanine, on Cu(1 1 0) was investigated by variable temperature scanning tunneling microscopy (STM). At low coverage and for temperatures above ≈-220 K the molecules nucleate along the [ 3¯ 3 2] direction to form short, mainly one-dimensional islands. An increase in coverage leads to the formation of [ 3¯ 3 2]-directed, elongated islands. Images with sub-molecular resolution reveal that the orientation of the molecules within one particular island depends on the deposition temperature. At higher coverage, up to one monolayer, the islands coalesce, giving rise to phase boundaries between domains of opposite orientation. An atomic-scale model for di- L-alanine on Cu(1 1 0) is presented.

  15. Computer graphic method for direct correspondence image acquisition used in full parallax holographic stereograms

    NASA Astrophysics Data System (ADS)

    Madrid Sánchez, Alejandro; Velásquez Prieto, Daniel

    2016-09-01

    The holoprinter technology based on holographic stereograms has generated a fast development in holographic display applications by the holographic recording of a 2D image sequence with information of a 3D scene, which could be real or computer generated. The images used in holographic stereograms initially start from the acquisition of the different image perspectives of the 3D scene by the re-centering camera configuration and then, this images must be rearranged before the optical recording. This paper proposes a method to acquire the required images or hogel images in one step without using rearrange algorithms, the method uses a virtual camera that moves along a virtual rail by conventional computer graphics software. The proposed method reduced the time required to obtain the hogel images and enhance the quality of the 3D holographic images; it also can be applied in different computer graphics software. To validate the method, a full parallax holographic stereogram was made for a computer generated object.

  16. Large-Scale medical image analytics: Recent methodologies, applications and Future directions.

    PubMed

    Zhang, Shaoting; Metaxas, Dimitris

    2016-10-01

    Despite the ever-increasing amount and complexity of annotated medical image data, the development of large-scale medical image analysis algorithms has not kept pace with the need for methods that bridge the semantic gap between images and diagnoses. The goal of this position paper is to discuss and explore innovative and large-scale data science techniques in medical image analytics, which will benefit clinical decision-making and facilitate efficient medical data management. Particularly, we advocate that the scale of image retrieval systems should be significantly increased at which interactive systems can be effective for knowledge discovery in potentially large databases of medical images. For clinical relevance, such systems should return results in real-time, incorporate expert feedback, and be able to cope with the size, quality, and variety of the medical images and their associated metadata for a particular domain. The design, development, and testing of the such framework can significantly impact interactive mining in medical image databases that are growing rapidly in size and complexity and enable novel methods of analysis at much larger scales in an efficient, integrated fashion.

  17. Direct imaging of hydrogen-atom columns in a crystal by annular bright-field electron microscopy.

    PubMed

    Ishikawa, Ryo; Okunishi, Eiji; Sawada, Hidetaka; Kondo, Yukihito; Hosokawa, Fumio; Abe, Eiji

    2011-04-01

    Enhancing the imaging power of microscopy to identify all chemical types of atom, from low- to high-atomic-number elements,would significantly contribute for a direct determination of material structures. Electron microscopes have successfully provided images of heavy-atom positions, particularly by the annular dark-field method, but detection of light atoms was difficult owing to their weak scattering power. Recent developments of aberration-correction electron optics have significantly advanced the microscope performance, enabling identification of individual light atoms such as oxygen, nitrogen, carbon, boron and lithium. However, the lightest hydrogen atom has not yet been observed directly, except in the specific condition of hydrogen adatoms on a graphene membrane. Here we show the first direct imaging of the hydrogen atom in a crystalline solid YH(2), based on a classic 'hollow-cone' illumination theory combined with state-of-the-art scanning transmission electronmicroscopy. The optimized hollow-cone condition derived from the aberration-corrected microscope parameters confirms that the information transfer can be extended to 22.5 nm(-1), which corresponds to a spatial resolution of about 44.4 pm. These experimental conditions can be readily realized with the annular bright-field imaging in scanning transmission electron microscopy according to reciprocity, revealing successfully the hydrogen-atom columns as dark dots, as anticipated from phase contrast of a weak-phase object.

  18. Matrix Pre-Coated Targets for Direct Lipid Analysis and Imaging of Tissue

    PubMed Central

    Yang, Junhai; Caprioli, Richard M.

    2013-01-01

    We have developed targets pre-coated with matrix for imaging lipids in tissues using MALDI-MS. Thin tissue sections (rat kidney and mouse or rat brains) were placed onto 2,5-diaminonaphthalene pre-coated targets (prepared beforehand by a protocol utilizing sublimation) and were washed with ammonium formate solution. After a brief drying period, the target slides were imaged by MALDI MS. The resulting images from these sections were of equivalent quality to those obtained using the usual post-coating approach such as sublimation and spraying in term of the sharpness of substructures in the images demonstrated by imaging at spatial resolutions of 100, 10 and 5 μm. Matrix pre-coated targets have a shelf-life more than 6 months when kept in a dark, non-humid environment such as a non-transparent desiccator. PMID:23418860

  19. Laser desorption/ionization mass spectrometry for direct profiling and imaging of small molecules from raw biological materials

    SciTech Connect

    Cha, Sangwon

    2008-01-01

    Matrix-assisted laser desorption/ionization(MALDI) mass spectrometry(MS) has been widely used for analysis of biological molecules, especially macromolecules such as proteins. However, MALDI MS has a problem in small molecule (less than 1 kDa) analysis because of the signal saturation by organic matrixes in the low mass region. In imaging MS (IMS), inhomogeneous surface formation due to the co-crystallization process by organic MALDI matrixes limits the spatial resolution of the mass spectral image. Therefore, to make laser desorption/ionization (LDI) MS more suitable for mass spectral profiling and imaging of small molecules directly from raw biological tissues, LDI MS protocols with various alternative assisting materials were developed and applied to many biological systems of interest. Colloidal graphite was used as a matrix for IMS of small molecules for the first time and methodologies for analyses of small metabolites in rat brain tissues, fruits, and plant tissues were developed. With rat brain tissues, the signal enhancement for cerebroside species by colloidal graphite was observed and images of cerebrosides were successfully generated by IMS. In addition, separation of isobaric lipid ions was performed by imaging tandem MS. Directly from Arabidopsis flowers, flavonoids were successfully profiled and heterogeneous distribution of flavonoids in petals was observed for the first time by graphite-assisted LDI(GALDI) IMS.

  20. The Atmospheres of Directly Imaged Planets: Where Has All the Methane Gone?

    NASA Technical Reports Server (NTRS)

    Marley, Mark S.; Zahnle, Kevin

    2014-01-01

    Methane and ammonia both first appear at lower effective temperatures in brown dwarf atmospheres than equilibrium chemistry models would suggest. This has traditionally been understood as a consequence of vertical mixing timescales being shorter than chemical equilibration timescales in brown dwarf photospheres. Indeed the eddy diffusivity, a variable accounting for the vigor of vertical mixing, has become a standard part of the description of brown dwarf atmosphere models, along with Teff and log g. While some models have suggested that methane is less favored at lower gravity, the almost complete absence of methane in the atmospheres of directly imaged planets, such as those orbiting HR 8799, even at effective temperatures where methane is readily apparent in brown dwarf spectra, has been puzzling. To better understand the paucity of methane in low gravity atmospheres we have revisited the problem of methane chemistry and mixing. We employed a 1-D atmospheric chemistry code augmented with an updated and complete network of the chemical reactions that link CO to CH4. We find the methane abundance at altitudes at or above the effective photosphere is a strong function of surface gravity because higher g shifts the p-T structure to higher pressures (i.e., a given optical depth is proportional to p/g, a relation mitigated somewhat by pressure broadening). Thus quenching in more massive brown dwarfs occurs at a lower temperature and higher pressure, both favoring CH4. We predict that in the lowest mass young giant planets, methane will appear very late, at effective temperatures as low as 600 K rather than the 1200 K seen among field brown dwarfs. This methane deficiency has important implications for the interpretation of spectra as well as methane-based planetary companion searches, such as the NICI survey. The GPI and SPHERE surveys will test these ideas and probe atmospheric chemistry and composition in an entire new range of parameter space. A caveat is that

  1. Incidental vesicocolic fistula on routine bone scintigraphy: Value of additional delayed images and direct radionuclide cystography.

    PubMed

    Sohn, Myung-Hee; Tae Lim, Seok; Jin Jeong, Young; Wook Kim, Dong; Jeong, Hwan-Jeong; Yim, Chang-Yeol

    2010-09-01

    An unexpected vesicocolic fistula can be detected incidentally on routine bone scintigraphy. A 55-year-old man who had a radical colectomy for carcinoma of the sigmoid colon 1 year previously underwent bone scintigraphy to evaluate bone metastasis. Whole-body images showed an abnormal accumulation of radioactivity in the right lower quadrant of the abdomen, but the radioactivity did not precisely define a structure. Additional delayed images obtained after 15 and 24 hours of the initial image localized a vesicocolic fistula. Subsequent radionuclide cystography confirmed leakage of the radioactivity from the bladder.

  2. TU-G-BRA-02: Can We Extract Lung Function Directly From 4D-CT Without Deformable Image Registration?

    SciTech Connect

    Kipritidis, J; Woodruff, H; Counter, W; Keall, P; Hofman, M; Siva, S; Callahan, J; Le Roux, P; Hardcastle, N

    2015-06-15

    Purpose: Dynamic CT ventilation imaging (CT-VI) visualizes air volume changes in the lung by evaluating breathing-induced lung motion using deformable image registration (DIR). Dynamic CT-VI could enable functionally adaptive lung cancer radiation therapy, but its sensitivity to DIR parameters poses challenges for validation. We hypothesize that a direct metric using CT parameters derived from Hounsfield units (HU) alone can provide similar ventilation images without DIR. We compare the accuracy of Direct and Dynamic CT-VIs versus positron emission tomography (PET) images of inhaled {sup 68}Ga-labelled nanoparticles (‘Galligas’). Methods: 25 patients with lung cancer underwent Galligas 4D-PET/CT scans prior to radiation therapy. For each patient we produced three CT- VIs. (i) Our novel method, Direct CT-VI, models blood-gas exchange as the product of air and tissue density at each lung voxel based on time-averaged 4D-CT HU values. Dynamic CT-VIs were produced by evaluating: (ii) regional HU changes, and (iii) regional volume changes between the exhale and inhale 4D-CT phase images using a validated B-spline DIR method. We assessed the accuracy of each CT-VI by computing the voxel-wise Spearman correlation with free-breathing Galligas PET, and also performed a visual analysis. Results: Surprisingly, Direct CT-VIs exhibited better global correlation with Galligas PET than either of the dynamic CT-VIs. The (mean ± SD) correlations were (0.55 ± 0.16), (0.41 ± 0.22) and (0.29 ± 0.27) for Direct, Dynamic HU-based and Dynamic volume-based CT-VIs respectively. Visual comparison of Direct CT-VI to PET demonstrated similarity for emphysema defects and ventral-to-dorsal gradients, but inability to identify decreased ventilation distal to tumor-obstruction. Conclusion: Our data supports the hypothesis that Direct CT-VIs are as accurate as Dynamic CT-VIs in terms of global correlation with Galligas PET. Visual analysis, however, demonstrated that different CT

  3. Direct magnitude and phase imaging of myelin using ultrashort echo time (UTE) pulse sequences: A feasibility study.

    PubMed

    He, Qun; Ma, Yajun; Fan, Shujuan; Shao, Hongda; Sheth, Vipul; Bydder, Graeme M; Du, Jiang

    2017-02-20

    In this paper, we aimed to investigate the feasibility of direct visualization of myelin, including myelin lipid and myelin basic protein (MBP), using two-dimensional ultrashort echo time (2D UTE) sequences and utilize phase information as a contrast mechanism in phantoms and in volunteers. The standard UTE sequence was used to detect both myelin and long T2 signal. An adiabatic inversion recovery UTE (IR-UTE) sequence was used to selectively detect myelin by suppressing signal from long T2 water protons. Magnitude and phase imaging and T2* were investigated on myelin lipid and MBP in the forms of lyophilized powders as well as paste-like phantoms with the powder mixed with D2O, and rubber phantoms as well as healthy volunteers. Contrast to noise ratio (CNR) between white and gray matter was measured. Both magnitude and phase images were generated for myelin and rubber phantoms as well white matter in vivo using the IR-UTE sequence. T2* values of ~300μs were comparable for myelin paste phantoms and the short T2* component in white matter of the brain in vivo. Mean CNR between white and gray matter in IR-UTE imaging was increased from -7.3 for the magnitude images to 57.4 for the phase images. The preliminary results suggest that the IR-UTE sequence allows simultaneous magnitude and phase imaging of myelin in vitro and in vivo.

  4. Automatic detection of motion blur in intravital video microscopy image sequences via directional statistics of log-Gabor energy maps.

    PubMed

    Ferrari, Ricardo J; Pinto, Carlos H Villa; da Silva, Bruno C Gregório; Bernardes, Danielle; Carvalho-Tavares, Juliana

    2015-02-01

    Intravital microscopy is an important experimental tool for the study of cellular and molecular mechanisms of the leukocyte-endothelial interactions in the microcirculation of various tissues and in different inflammatory conditions of in vivo specimens. However, due to the limited control over the conditions of the image acquisition, motion blur and artifacts, resulting mainly from the heartbeat and respiratory movements of the in vivo specimen, will very often be present. This problem can significantly undermine the results of either visual or computerized analysis of the acquired video images. Since only a fraction of the total number of images are usually corrupted by severe motion blur, it is necessary to have a procedure to automatically identify such images in the video for either further restoration or removal. This paper proposes a new technique for the detection of motion blur in intravital video microscopy based on directional statistics of local energy maps computed using a bank of 2D log-Gabor filters. Quantitative assessment using both artificially corrupted images and real microscopy data were conducted to test the effectiveness of the proposed method. Results showed an area under the receiver operating characteristic curve (AUC) of 0.95 (AUC = 0.95; 95 % CI 0.93-0.97) when tested on 329 video images visually ranked by four observers.

  5. DIRC Dreams: Research Directions for the Next Generation of Internally Reflected Imaging Counters

    SciTech Connect

    Ratcliff, Blair N.

    1999-08-17

    Some conceptual design features of the total internally reflecting,imaging Cherenkov counter (DIRC) are described. Limits of the DIRC approach to particle identification, and a few features of alternative DIRC designs, are briefly explored.

  6. DIRC Dreams Redux: Research Directions for the Next Generation of Internally Reflected Imaging Counters

    SciTech Connect

    Ratcliff, Blair N

    2001-09-18

    Some general conceptual design features of total internally reflecting, imaging Cherenkov counters (DIRCs) are described. Limits of the DIRC approach to particle identification and a few features of alternative DIRC designs are briefly explored.

  7. Retinal imaging in the twenty-first century: state of the art and future directions.

    PubMed

    Keane, Pearse A; Sadda, Srinivas R

    2014-12-01

    Assessment of chorioretinal disease is dependent on the ability to visualize pathologic changes occurring in the posterior segment of the eye using optical instruments, termed ophthalmoscopy. Ophthalmoscopy, in turn, has been enhanced greatly by the development of techniques that allow recording of these changes, termed retinal imaging. As well as documenting pathologic features, retinal and fundal imaging facilitates the identification of morphologic features not visible to the clinician on biomicroscopy. As such, advances in retinal imaging have proven fundamental to many paradigm shifts in our understanding and treatment of ocular disease. In the 1950s, with the advent of electronic flashes and 35-mm cameras, the field of modern fundus photography was born. Similarly, in the 1960s and 1970s, the introduction of fluorescein and indocyanine green angiography revolutionized our ability to assess the integrity of the chorioretinal vasculature. More recently, in the 1990s, the introduction of a wholly new form of noninvasive cross-sectional imaging, optical coherence tomography, has greatly facilitated use of emerging pharmacotherapies in diagnosing and monitoring chorioretinal disease. In this translational science review, we provide an overview of current, state-of-the-art retinal imaging technologies, as well as highlight many emerging imaging technologies that we believe are likely to transform the provision of eye care in the 21st century.

  8. DIRECT IMAGE PROCESSING OF CORRODING SURFACES APPLIED TO FRICTION STIR WELDING.

    SciTech Connect

    ISAACS,H.S.ET AL.

    2003-10-12

    An in situ process for visually locating corrosion is presented. The process visually displays image differences obtained by subtracting one digitized image from another. The difference image shows only where changes have taken place during period between the recording of the two images. Changes are due to both corrosion attack of the surface and concentration changes of dissolved corrosion products in solution. Indicators added to the solution assist by decorating sites of corrosion as diffusion and convection of the dissolved products increase the size of the affected region. A study of the initial stages of corrosion of a friction stir welded Al alloy 7075 has been performed using this imaging technique. Pitting potential measurements suggest that there was an initial increased sensitivity to corrosion. The difference image technique demonstrated that it was due to a reformation of the passive film that occurs with Zn containing Al alloys which occurs preferentially along flow protected regions. The most susceptible region of the weld was found to be where both limited deformation and thermal transients are produced during welding.

  9. Direct imaging with a dense aperture masking in comparison with a telescope or a hypertelelescope

    NASA Astrophysics Data System (ADS)

    Patru, Fabien; Antichi, Jacopo; Girard, Julien

    2011-10-01

    Dense Aperture Masking (DAM) is a new interferometric technique allowing high-angular resolution over a narrow field of view (FOV) imaged by the present class of mono-pupil telescopes equipped with adaptive optics (AO). DAM is realized by a suited afocal double lenslet array (BIGRE), remapping the entrance aperture (telescope pupil) into coherent sub-apertures (sub-pupils), and adopted as sub-pupils spatial filter and re-imager.We focus our attention on the point spread function (PSF) properties of DAM, highlighting those related to spatial sampling and filtering of the frequency coverage of the entrance pupil.We stress why the high spatial frequency sampling of the pupil and the low spatial frequency filtering of the sub-pupils are consistent with both a mono-pupil (telescope) and an array of sub-pupils (hypertelescope). We explain how DAM provides high Strehl and high-angular resolution images, first by filtering the low frequencies, which in turn are not so well corrected with a standard AO, second by preserving an object-image convolution relation over a narrow FOV. Finally, we make a comparison with the imaging properties of a telescope and a hypertelescope with the aim to show the complementary of DAM with other techniques adopted in high-contrast imaging.

  10. Characterisation of a smartphone image sensor response to direct solar 305nm irradiation at high air masses.

    PubMed

    Igoe, D P; Amar, A; Parisi, A V; Turner, J

    2017-06-01

    This research reports the first time the sensitivity, properties and response of a smartphone image sensor that has been used to characterise the photobiologically important direct UVB solar irradiances at 305nm in clear sky conditions at high air masses. Solar images taken from Autumn to Spring were analysed using a custom Python script, written to develop and apply an adaptive threshold to mitigate the effects of both noise and hot-pixel aberrations in the images. The images were taken in an unobstructed area, observing from a solar zenith angle as high as 84° (air mass=9.6) to local solar maximum (up to a solar zenith angle of 23°) to fully develop the calibration model in temperatures that varied from 2°C to 24°C. The mean ozone thickness throughout all observations was 281±18 DU (to 2 standard deviations). A Langley Plot was used to confirm that there were constant atmospheric conditions throughout the observations. The quadratic calibration model developed has a strong correlation between the red colour channel from the smartphone with the Microtops measurements of the direct sun 305nm UV, with a coefficient of determination of 0.998 and very low standard errors. Validation of the model verified the robustness of the method and the model, with an average discrepancy of only 5% between smartphone derived and Microtops observed direct solar irradiances at 305nm. The results demonstrate the effectiveness of using the smartphone image sensor as a means to measure photobiologically important solar UVB radiation. The use of ubiquitous portable technologies, such as smartphones and laptop computers to perform data collection and analysis of solar UVB observations is an example of how scientific investigations can be performed by citizen science based individuals and groups, communities and schools.

  11. DIRECT IMAGING OF A COLD JOVIAN EXOPLANET IN ORBIT AROUND THE SUN-LIKE STAR GJ 504

    SciTech Connect

    Kuzuhara, M.; Tamura, M.; Kandori, R.; Hori, Y.; Suzuki, R.; Suenaga, T.; Takahashi, Y. H.; Kwon, J.; Kudo, T.; Janson, M.; Brandt, T. D.; Spiegel, D.; Burrows, A.; Turner, E. L.; Moro-Martin, A.; Thalmann, C.; Biller, B.; Henning, T.; Carson, J.; McElwain, M. W.; and others

    2013-09-01

    Several exoplanets have recently been imaged at wide separations of >10 AU from their parent stars. These span a limited range of ages (<50 Myr) and atmospheric properties, with temperatures of 800-1800 K and very red colors (J - H > 0.5 mag), implying thick cloud covers. Furthermore, substantial model uncertainties exist at these young ages due to the unknown initial conditions at formation, which can lead to an order of magnitude of uncertainty in the modeled planet mass. Here, we report the direct-imaging discovery of a Jovian exoplanet around the Sun-like star GJ 504, detected as part of the SEEDS survey. The system is older than all other known directly imaged planets; as a result, its estimated mass remains in the planetary regime independent of uncertainties related to choices of initial conditions in the exoplanet modeling. Using the most common exoplanet cooling model, and given the system age of 160{sup +350}{sub -60} Myr, GJ 504b has an estimated mass of 4{sup +4.5}{sub -1.0} Jupiter masses, among the lowest of directly imaged planets. Its projected separation of 43.5 AU exceeds the typical outer boundary of {approx}30 AU predicted for the core accretion mechanism. GJ 504b is also significantly cooler (510{sup +30}{sub -20} K) and has a bluer color (J - H = -0.23 mag) than previously imaged exoplanets, suggesting a largely cloud-free atmosphere accessible to spectroscopic characterization. Thus, it has the potential of providing novel insights into the origins of giant planets as well as their atmospheric properties.

  12. Direct Imaging of a Cold Jovian Exoplanet in Orbit around the Sun-Like Star GJ 504

    NASA Technical Reports Server (NTRS)

    Kuzuhara, M.; Tamura, M.; Kudo, T.; Janson, M; Kandori, R.; Brandt, T. D.; Thalmann, C.; Spiegel, D.; Biller, B.; Carson, J.; Hori, Y.; Suzuki, R.; Burrows, A.; Henning, T.; Turner, E. L.; McElwain, M. W.; Moro-Martin, A.; Suenaga, T.; Takahashi, Y. H.; Kwon, J.; Lucas, P.; Abe, L.; Brandner, W.; Grady, C. A.; Serabyn, E.

    2013-01-01

    Several exoplanets have recently been imaged at wide separations of >10 AU from their parent stars. These span a limited range of ages (<50 Myr) and atmospheric properties, with temperatures of 800-1800 K and very red colors (J -H > 0.5 mag), implying thick cloud covers. Furthermore, substantial model uncertainties exist at these young ages due to the unknown initial conditions at formation, which can lead to an order of magnitude of uncertainty in the modeled planet mass. Here, we report the direct imaging discovery of a Jovian exoplanet around the Sun-like star GJ 504, detected as part of the SEEDS survey. The system is older than all other known directly-imaged planets; as a result, its estimated mass remains in the planetary regime independent of uncertainties related to choices of initial conditions in the exoplanet modeling. Using the most common exoplanet cooling model, and given the system age of 160(+350/-60) Myr, GJ 504 b has an estimated mass of 4(+4.5/-1.0) Jupiter masses, among the lowest of directly imaged planets. Its projected separation of 43.5 AU exceeds the typical outer boundary of approx.. 30 AU predicted for the core accretion mechanism. GJ 504 b is also significantly cooler (510(+30/-20) K)) and has a bluer color (J - H = -0.23 mag) than previously imaged exoplanets, suggesting a largely cloud-free atmosphere accessible to spectroscopic characterization. Thus, it has the potential of providing novel insights into the origins of giant planets, as well as their atmospheric properties.

  13. Direct visualization of regions with lowered bone mineral density in dual-energy CT images of vertebrae

    NASA Astrophysics Data System (ADS)

    Wesarg, Stefan; Erdt, Marius; Kafchitsas, Konstantinos; Khan, M. Fawad

    2011-03-01

    Dual-energy CT allows for a better material differentiation than conventional CT. For the purpose of osteoporosis diagnosis, a detection of regions with lowered bone mineral density (BMD) is of high clinical interest. Based on an existing biophysical model of the trabecular bone in vertebrae a new method for directly highlighting those low density regions in the image data has been developed. For this, we combine image data acquired at 80 kV and 140 kV with information about the BMD range in different vertebrae and derive a method for computing a color enhanced image which clearly indicates low density regions. An evaluation of our method which compares it with a quantitative method for BMD assessment shows a very good correspondence between both methods. The strength of our method lies in its simplicity and speed.

  14. Direct Imaging of Protein Organization in an Intact Bacterial Organelle Using High-Resolution Atomic Force Microscopy

    PubMed Central

    2016-01-01

    The function of bioenergetic membranes is strongly influenced by the spatial arrangement of their constituent membrane proteins. Atomic force microscopy (AFM) can be used to probe protein organization at high resolution, allowing individual proteins to be identified. However, previous AFM studies of biological membranes have typically required that curved membranes are ruptured and flattened during sample preparation, with the possibility of disruption of the native protein arrangement or loss of proteins. Imaging native, curved membranes requires minimal tip–sample interaction in both lateral and vertical directions. Here, long-range tip–sample interactions are reduced by optimizing the imaging buffer. Tapping mode AFM with high-resonance-frequency small and soft cantilevers, in combination with a high-speed AFM, reduces the forces due to feedback error and enables application of an average imaging force of tens of piconewtons. Using this approach, we have imaged the membrane organization of intact vesicular bacterial photosynthetic “organelles”, chromatophores. Despite the highly curved nature of the chromatophore membrane and lack of direct support, the resolution was sufficient to identify the photosystem complexes and quantify their arrangement in the native state. Successive imaging showed the proteins remain surprisingly static, with minimal rotation or translation over several-minute time scales. High-order assemblies of RC-LH1-PufX complexes are observed, and intact ATPases are successfully imaged. The methods developed here are likely to be applicable to a broad range of protein-rich vesicles or curved membrane systems, which are an almost ubiquitous feature of native organelles. PMID:28114766

  15. Live dynamic OCT imaging of cardiac structure and function in mouse embryos with 43 Hz direct volumetric data acquisition

    NASA Astrophysics Data System (ADS)

    Wang, Shang; Singh, Manmohan; Lopez, Andrew L.; Wu, Chen; Raghunathan, Raksha; Schill, Alexander; Li, Jiasong; Larin, Kirill V.; Larina, Irina V.

    2016-03-01

    Efficient phenotyping of cardiac dynamics in live mouse embryos has significant implications on understanding of early mammalian heart development and congenital cardiac defects. Recent studies established optical coherence tomography (OCT) as a powerful tool for live embryonic heart imaging in various animal models. However, current four-dimensional (4D) OCT imaging of the beating embryonic heart largely relies on gated data acquisition or postacquisition synchronization, which brings errors when cardiac cycles lack perfect periodicity and is time consuming and computationally expensive. Here, we report direct 4D OCT imaging of the structure and function of cardiac dynamics in live mouse embryos achieved by employing a Fourier domain mode-locking swept laser source that enables ~1.5 MHz A-line rate. Through utilizing both forward and backward scans of a resonant mirror, we obtained a ~6.4 kHz frame rate, which allows for a direct volumetric data acquisition speed of ~43 Hz, around 20 times of the early-stage mouse embryonic heart rate. Our experiments were performed on mouse embryos at embryonic day 9.5. Time-resolved 3D cardiodynamics clearly shows the heart structure in motion. We present analysis of cardiac wall movement and its velocity from the primitive atrium and ventricle. Our results suggest that the combination of ultrahigh-speed OCT imaging with live embryo culture could be a useful embryonic heart phenotyping approach for mouse mutants modeling human congenital heart diseases.

  16. Direct imaging of the structure, relaxation, and sterically constrained motion of encapsulated tungsten polyoxometalate lindqvist ions within carbon nanotubes.

    PubMed

    Sloan, Jeremy; Matthewman, Gemma; Dyer-Smith, Clare; Sung, A-Young; Liu, Zheng; Suenaga, Kazu; Kirkland, Angus I; Flahaut, Emmanuel

    2008-05-01

    The imaging properties and observation of the sterically regulated translational motion of discrete tungsten polyoxometalate Linqvist ions (i.e., [W(6)O(19)](2-)) within carbon nanotubes of specific internal diameter are reported. The translational motion of the nonspheroidal anion within the nanotube capillary is found to be impeded by its near-perfect accommodation to the internal van der Waals surface of the nanotube wall. Rotational motion of the anion about one remaining degree of freedom permits translational motion of the anion along the nanotube followed by locking in at sterically favorable positions in a mechanism similar to a molecular ratchet. This steric locking permits the successful direct imaging of the constituent octahedral cation template of individual [W(6)O(19)](2-) anions by high resolution transmission electron microscopy thereby permitting meterological measurements to be performed directly on the anion. Direct imaging of pairs of equatorial W(2) atoms within the anion reveal steric relaxation of the anion contained within the nanotube capillary relative to the bulk anion structure.

  17. The Water Abundance of the Directly Imaged Substellar Companion κ And b Retrieved from a Near Infrared Spectrum

    NASA Astrophysics Data System (ADS)

    Todorov, Kamen O.; Line, Michael R.; Pineda, Jaime E.; Meyer, Michael R.; Quanz, Sascha P.; Hinkley, Sasha; Fortney, Jonathan J.

    2016-05-01

    Spectral retrieval has proven to be a powerful tool for constraining the physical properties and atmospheric compositions of extrasolar planet atmospheres based on observed spectra, primarily for transiting objects but also for directly imaged planets and brown dwarfs. Despite its strengths, this approach has been applied to only about a dozen targets. Determining the abundances of the main carbon- and oxygen-bearing compounds in a planetary atmosphere can lead to the C/O ratio of the object, which is crucial for understanding its formation and migration history. We present a retrieval analysis of the published near-infrared spectrum of κ \\quad {Andromedae} b, a directly imaged substellar companion to a young B9 star. We fit the emission spectrum model utilizing a Markov Chain Monte Carlo algorithm. We estimate the abundance of water vapor, and its uncertainty, in the atmosphere of the object. In addition, we place an upper limit on the abundance of CH4. We qualitatively compare our results with studies that have applied model retrieval on multiband photometry and emission spectroscopy of hot Jupiters (extrasolar giant planets with orbital periods of several days) and the directly imaged giant planet HR 8799b.

  18. Novel technique to retrieve the direct normal irradiance from SEVIRI images over the UAE

    NASA Astrophysics Data System (ADS)

    Ghedira, H.; Eissa, Y. A.

    2011-12-01

    Satellite-based models that determine direct normal irradiance (DNI) values with high temporal resolution have relatively high RMSE values. In this study, an artificial neural network (ANN) approach was developed to derive DNI values from SEVIRI images under a wide range of sun-satellite geometries. The final product has a temporal resolution of 15 minutes and a spatial resolution of 3 km. ANNs, which imitate the way the brain processes information, are systems that can be trained with sets of inputs and outputs in order to find the best pattern that provides the best match. Given a set of inputs the ANN could then simulate the corresponding output. There are different types of neural networks; the one proposed here is the multilayer perceptron (MLP), which is known to have the capability to solve nonlinear and complex problems. Several ANN-based techniques have been developed recently to estimate global horizontal radiation, but only ground-based meteorological measurements were used as inputs. The MLP ANN is proposed here given the complexity of the non-linear relationship between DNI and satellite measurements. Complex combination and interaction of several atmospheric parameters contribute to the total DNI attenuation and the contributions of each of these parameters are not usually measurable. Such parameters include air molecules, water vapor, water droplets, ozone, carbon dioxide and dust. An MLP ANN tool was designed to estimate the total optical depth of the atmosphere (δ) which includes all the attenuating parameters. This is followed from the Beer-Bouguer-Lambert law: DNI = I0*ɛ*exp(-δm) where I0 is the solar constant, ɛ is the sun-earth distance correction, and m is the air mass. δ values computed from ground-measured DNI values were used as truth data in training the ANN. The ground-measured DNI values were measured using a Rotating Shadow Band Pyranometer at 10-minute resolution. This instrument consists of a pyranometer which measures the global

  19. Evolution of Satellite Imagers and Sounders for Low Earth Orbit and Technology Directions at NASA

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; McClain, Charles R.

    2010-01-01

    Imagers and Sounders for Low Earth Orbit (LEO) provide fundamental global daily observations of the Earth System for scientists, researchers, and operational weather agencies. The imager provides the nominal 1-2 km spatial resolution images with global coverage in multiple spectral bands for a wide range of uses including ocean color, vegetation indices, aerosol, snow and cloud properties, and sea surface temperature. The sounder provides vertical profiles of atmospheric temperature, water vapor cloud properties, and trace gases including ozone, carbon monoxide, methane and carbon dioxide. Performance capabilities of these systems has evolved with the optical and sensing technologies of the decade. Individual detectors were incorporated on some of the first imagers and sounders that evolved to linear array technology in the '80's. Signal-to-noise constraints limited these systems to either broad spectral resolution as in the case of the imager, or low spatial resolution as in the case of the sounder. Today's area 2-dimensional large format array technology enables high spatial and high spectral resolution to be incorporated into a single instrument. This places new constraints on the design of these systems and enables new capabilities for scientists to examine the complex processes governing the Earth System.

  20. Alternating direction optimization for image segmentation using hidden Markov measure field models

    NASA Astrophysics Data System (ADS)

    Bioucas-Dias, José; Condessa, Filipe; Kovačević, Jelena

    2014-02-01

    Image segmentation is fundamentally a discrete problem. It consists of finding a partition of the image domain such that the pixels in each element of the partition exhibit some kind of similarity. The solution is often obtained by minimizing an objective function containing terms measuring the consistency of the candidate partition with respect to the observed image, and regularization terms promoting solutions with desired properties. This formulation ends up being an integer optimization problem that, apart from a few exceptions, is NP-hard and thus impossible to solve exactly. This roadblock has stimulated active research aimed at computing "good" approximations to the solutions of those integer optimization problems. Relevant lines of attack have focused on the representation of the regions (i.e., the partition elements) in terms of functions, instead of subsets, and on convex relaxations which can be solved in polynomial time. In this paper, inspired by the "hidden Markov measure field" introduced by Marroquin et al. in 2003, we sidestep the discrete nature of image segmentation by formulating the problem in the Bayesian framework and introducing a hidden set of real-valued random fields determining the probability of a given partition. Armed with this model, the original discrete optimization is converted into a convex program. To infer the hidden fields, we introduce the Segmentation via the Constrained Split Augmented Lagrangian Shrinkage Algorithm (SegSALSA). The effectiveness of the proposed methodology is illustrated with simulated and real hyperspectral and medical images.

  1. Image-based analysis of primary human neutrophil chemotaxis in an automated direct-viewing assay

    PubMed Central

    Meyvantsson, Ivar; Vu, Elizabeth; Lamers, Casey; Echeverria, Daniella; Worzella, Tracy; Echeverria, Victoria; Skoien, Allyson; Hayes, Steven

    2011-01-01

    Multi-well assays based on the Boyden chamber have enabled highly parallel studies of chemotaxis – the directional migration of cells in response to molecular gradients – while direct-viewing approaches have allowed more detailed questions to be asked at low throughput. Boyden-based plates provide a count of cells that pass through a membrane, but no information about cell appearance. In contrast, direct viewing devices enable the observation of cells during chemotaxis, which allows measurement of many parameters including area, shape, and location. Here we show automated chemotaxis and cell morphology assays in a 96-unit direct-viewing plate. Using only 12,000 primary human neutrophils per datum, we measured dose-dependent stimulation and inhibition of chemotaxis and quantified the effects of inhibitors on cell area and elongation. With 60 parallel conditions we demonstrated 5-fold increase in throughput compared to previously reported direct viewing approaches. PMID:21215269

  2. Polarimetric imaging of NGC 1068 at high angular resolution in the near infrared. Direct evidence of an extended nuclear torus

    NASA Astrophysics Data System (ADS)

    Gratadour, D.; Rouan, D.; Grosset, L.; Boccaletti, A.; Clénet, Y.

    2015-09-01

    Aims: One of the main observational challenges for investigating the central regions of active galactic nuclei (AGN) at short wavelengths, using high angular resolution, and high contrast observations, is to directly detect the circumnuclear optically thick material hiding the central core emission when viewed edge-on. The lack of direct evidence is limiting our understanding of AGN, and several scenarios have been proposed to cope for the diverse observed aspects of activity in a unified approach. Methods: Observations in the near-infrared spectral range have shown themselves to be powerful for providing essential hints to the characterisation of the unified model ingredients because of the reduced optical depth of the obscuring material. Moreover, it is possible to trace this material through light scattered from the central engine's closest environment, so that polarimetric observations are the ideal tool for distinguishing it from purely thermal and stellar emissions. Results: Here we show strong evidence that there is an extended nuclear torus at the center of NGC 1068 thanks to new adaptive-optics-assisted polarimetric observations in the near-infrared. The orientation of the polarization vectors proves that there is a structured hourglass-shaped bicone and a compact elongated (20 × 60 pc) nuclear structure perpendicular to the bicone axis. The linearly polarized emission in the bicone is dominated by a centro-symmetric pattern, but the central compact region shows a clear deviation from the latter with linear polarization aligned perpendicular to the bicone axis. Figure 2 is available in electronic form at http://www.aanda.orgData obtained with the SPHERE an instrument designed and built by a consortium consisting of IPAG (France), MPIA (Germany), LAM (France), LESIA (France), Laboratoire Lagrange (France), INAF - Osservatorio di Padova (Italy), Observatoire de Genève (Switzerland), ETH Zurich (Switzerland), NOVA (Netherlands), ONERA (France), and ASTRON

  3. Nucleic Acid-directed Self-assembly of Multifunctional Gold Nanoparticle Imaging Agents1

    PubMed Central

    Zhang, Ziyan; Liu, Yongjian; Jarreau, Chad; Welch, Michael J.; Taylor, John-Stephen A.

    2013-01-01

    Gold nanoparticles have attracted much interest as a platform for development of multifunctional imaging and therapeutic agents. Multifunctionalized gold nanoparticles are generally constructed by covalent assembly of a gold core with thiolated ligands. In this study, we have assembled multifunctionalized gold nanoparticles in one step by nucleic acid hybridization of ODN (oligodeoxynucleotide)-derivatized gold nanoparticles with a library of pre-functionalized complementary PNAs (peptide nucleic acids). The PNAs were functionalized by conjugation with DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) for chelating 64Cu for PET imaging, PEG (polyethylene glycol) for conferring stealth properties, and Cy5 for fluorescent imaging. The resulting nanoparticles showed good stability both in vitro and in vivo showing biodistribution behavior in a mouse that would be expected for a PEGylated gold nanoparticle rather than that for the radiolabelled PNA used in its assembly. PMID:24058728

  4. Direct Imaging of Single Cells and Tissue at Subcellular Spatial Resolution Using Transmission Geometry MALDI MS

    PubMed Central

    Zavalin, Andre; Todd, Erik M.; Rawhouser, Patrick D.; Yang, Junhai; Norris, Jeremy L.; Caprioli, Richard M.

    2012-01-01

    The need of cellular and sub-cellular spatial resolution in LDI / MALDI Imaging Mass Spectrometry (IMS) necessitates micron and sub-micron laser spot sizes at biologically relevant sensitivities, introducing significant challenges for MS technology. To this end we have developed a transmission geometry vacuum ion source that allows the laser beam to irradiate the back side of the sample. This arrangement obviates the mechanical / ion optic complications in the source by completely separating the optical lens and ion optic structures. We have experimentally demonstrated the viability of transmission geometry MALDI MS for imaging biological tissues and cells with sub-cellular spatial resolution. Furthermore, we demonstrate that in conjunction with new sample preparation protocols, the sensitivity of this instrument is sufficient to obtain molecular images at sub-micron spatial resolution. PMID:23147833

  5. Discret aperture mapping with a micro-lenses array for interferometric direct imaging

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    A challenging study for high resolution and high-contrast imaging is the detection and the characterization of planets in the habitable zone. The problem of detection in imaging is due to both the contrast ratio and the tiny separation between the hosting star and the exoplanet. Certainly, many techniques in high-contrast imaging will have to be optimized simultaneously to enhance the detection treshold and to probe the candidates for life. In this context, the objective is to demonstrate the technical faisability and to get scientific returns with a new concept called Discret Aperture Mapping or DAM (Patru et al. 2011). DAM is a new interferometric technique allowing high contrast imaging over a narrow field of view imaged by the present class of mono-pupil telescopes equipped with adaptive optics (AO). DAM consists in mapping the telescope pupil to provide a correct sampling of the spatial frequency content of the telescope. DAM can be realized by an afocal double lenslet array array (BIGRE-DAM, Antichi et al. 2011), or by a single-mode fiber combiner (Fibered-DAM, Patru et al. 2008). The spatial filtering used in interferometry allows to subdivide the entrance pupil of a large telescope into many coherent sub-pupils, so that the intra-sub-pupil residual phase is averaged out. On the other side, frequencies higher than the deformable mirror sampling one are not corected by AO impling aliasing effect and a strong impact of Fresnel propagation on the compensated wavefront up to the final focus (Antichi et al. 2010). DAM is then a high frequency optical filter able to remove part of the AO residuals and to remove most of the halo in the image. It may improve the contrast limit to explore the inner region of new stellar systems (disk, exoplanet). We show here first simulation results on the DAM concept.

  6. Canadian Consensus Guidelines on Use of Amyloid Imaging in Canada: Update and Future Directions from the Specialized Task Force on Amyloid imaging in Canada.

    PubMed

    Laforce, Robert; Rosa-Neto, Pedro; Soucy, Jean-Paul; Rabinovici, Gil D; Dubois, Bruno; Gauthier, S

    2016-07-01

    Positron emission tomography (PET) imaging of brain amyloid beta is now clinically available in several countries including the United States and the United Kingdom, but not Canada. It has become an established technique in the field of neuroimaging of aging and dementia, with data incorporated in the new consensus guidelines for the diagnosis of Alzheimer disease and predementia Alzheimer's disease-related conditions. At this point, there are three US Food and Drug Administration- and European Union-approved tracers. Guided by appropriate use criteria developed in 2013 by the Alzheimer's Association and the Society of Nuclear Medicine and Molecular Imaging, the utility of amyloid imaging in medical practice is now supported by a growing body of research. In this paper, we aimed to provide an update on the 2012 Canadian consensus guidelines to dementia care practitioners on proper use of amyloid imaging. We also wished to generate momentum for the industry to submit a new drug proposal to Health Canada. A group of local, national, and international dementia experts and imaging specialists met to discuss scenarios in which amyloid PET could be used appropriately. Peer-reviewed and published literature between January 2004 and May 2015 was searched. Technical and regulatory considerations pertaining to Canada were considered. The results of a survey of current practices in Canadian dementia centers were considered. A set of specific clinical and research guidelines was agreed on that defines the types of patients and clinical circumstances in which amyloid PET could be used in Canada. Future research directions were also outlined, notably the importance of studies that would assess the pharmaco-economics of amyloid imaging.

  7. Efficient and robust 3D CT image reconstruction based on total generalized variation regularization using the alternating direction method.

    PubMed

    Chen, Jianlin; Wang, Linyuan; Yan, Bin; Zhang, Hanming; Cheng, Genyang

    2015-01-01

    Iterative reconstruction algorithms for computed tomography (CT) through total variation regularization based on piecewise constant assumption can produce accurate, robust, and stable results. Nonetheless, this approach is often subject to staircase artefacts and the loss of fine details. To overcome these shortcomings, we introduce a family of novel image regularization penalties called total generalized variation (TGV) for the effective production of high-quality images from incomplete or noisy projection data for 3D reconstruction. We propose a new, fast alternating direction minimization algorithm to solve CT image reconstruction problems through TGV regularization. Based on the theory of sparse-view image reconstruction and the framework of augmented Lagrange function method, the TGV regularization term has been introduced in the computed tomography and is transformed into three independent variables of the optimization problem by introducing auxiliary variables. This new algorithm applies a local linearization and proximity technique to make the FFT-based calculation of the analytical solutions in the frequency domain feasible, thereby significantly reducing the complexity of the algorithm. Experiments with various 3D datasets corresponding to incomplete projection data demonstrate the advantage of our proposed algorithm in terms of preserving fine details and overcoming the staircase effect. The computation cost also suggests that the proposed algorithm is applicable to and is effective for CBCT imaging. Theoretical and technical optimization should be investigated carefully in terms of both computation efficiency and high resolution of this algorithm in application-oriented research.

  8. DISCOVERY OF A PROBABLE 4-5 JUPITER-MASS EXOPLANET TO HD 95086 BY DIRECT IMAGING

    SciTech Connect

    Rameau, J.; Chauvin, G.; Lagrange, A.-M.; Delorme, P.; Quanz, S. P.; Bonnefoy, M.; Klahr, H.; Mordasini, C.; Girard, J. H.; Dumas, C.; Desidera, S.; Bonavita, M.

    2013-08-01

    Direct imaging has only begun to inventory the population of gas giant planets on wide orbits around young stars in the solar neighborhood. Following this approach, we carried out a deep imaging survey in the near-infrared using VLT/NaCo to search for substellar companions. Here we report the discovery of a probable companion orbiting the young (10-17 Myr), dusty, early-type (A8) star HD 95086 at 56 AU in L' (3.8 {mu}m) images. This discovery is based on observations with more than a year time lapse. Our first epoch clearly revealed the source at {approx_equal} 10{sigma}, while our second epoch lacks good observing conditions, yielding a {approx_equal} 3{sigma} detection. Various tests were thus made to rule out possible artifacts. This recovery is consistent with the signal at the first epoch but requires cleaner confirmation. Nevertheless, our astrometric precision suggests that the companion is comoving with the star with a 3{sigma} confidence level. The planetary nature of the source is reinforced by a non-detection in the Ks-band (2.18 {mu}m) images according to its possible extremely red Ks-L' color. Conversely, background contamination is rejected with good confidence level. The luminosity yields a predicted mass of about 4-5 M{sub Jup} (at 10-17 Myr) using ''hot-start'' evolutionary models, making HD 95086 b the exoplanet with the lowest mass ever imaged around a star.

  9. Direct Imaging in Interferometry: Concept of a Pupil D ensification Assembly Using Optical Fibers

    NASA Astrophysics Data System (ADS)

    Patru, F.; Mourard, D.; Lardière, O.; Clausse, J. M.; Antonelli, P.; Bresson, Y.; Lagarde, S.

    2005-12-01

    We present a test bench designed to study the performances of interferometric imaging systems. It aims at comparing the aperture synthesis, Fizeau and densified pupils beam combination schemes, mainly in the framework of the second generation instrument VIDA (VLTI Imaging with a Densified Array) of the VLTI. A Fizeau assembly has been achieved, using a multi-aperture mask and associated with a wavefront sensor. It allows identification of technical requirements like photometry and cophasing correction. A densified assembly is being studied which allows pupil rearrangement and spatial filtering by using single mode fibers. The goal here is to compare the expected densification properties allowed by monomode fibers with a classical optical scheme.

  10. Image reversal for direct electron beam patterning of protein coated surfaces.

    PubMed

    Pesen, Devrim; Erlandsson, Anna; Ulfendahl, Mats; Haviland, David B

    2007-11-01

    Electron beam lithography (EBL) is used to create surfaces with protein patterns, which are characterized by immunofluorescence and atomic force microscopies. Both negative and positive image processes are realized by electron beam irradiation of proteins absorbed on a silicon surface, where image reversal is achieved by selectively binding a second species of protein to the electron beam exposed areas on the first protein layer. Biofunctionality at the cellular level was established by culturing cortical cells on patterned lines of fibronectin adsorbed on a bovine serum albumin background for 7 days in culture.

  11. Direct optical imaging of graphene in vitro by nonlinear femtosecond laser spectral reshaping.

    PubMed

    Li, Baolei; Cheng, Yingwen; Liu, Jie; Yi, Congwen; Brown, April S; Yuan, Hsiangkuo; Vo-Dinh, Tuan; Fischer, Martin C; Warren, Warren S

    2012-11-14

    Nonlinear optical microscopy, based on femtosecond laser spectral reshaping, characterized and imaged graphene samples made from different methods, both on slides and in a biological environment. This technique clearly discriminates between graphene flakes with different numbers of layers and reveals the distinct nonlinear optical properties of reduced graphene oxide as compared to mechanically exfoliated or chemical vapor deposition grown graphene. The nonlinearity makes it applicable to scattering samples (such as tissue) as opposed to previous methods, such as transmission. This was demonstrated by high-resolution imaging of breast cancer cells incubated with graphene flakes.

  12. Extreme Exoplanet Direct Imaging: New Results with GPI and SCExAO and the Path to Imaging Another Earth

    NASA Astrophysics Data System (ADS)

    Currie, Thayne

    2015-12-01

    We describe the discovery of a bright, young Kuiper belt-like debris disk around HD 115600, a ˜ 1.4--1.5 M_{⊙}, ˜ 15 Myr old member of the Sco-Cen OB Association. Our H-band coronagraphy/integral field spectroscopy from the Gemini Planet Imager shows the ring has a (luminosity scaled) semi major axis of (˜ 22 AU) ˜ 48 AU, similar to the current Kuiper belt. The disk appears to have neutral scattering dust, is eccentric (e ˜ 0.1--0.2), and could be sculpted by analogues to the outer solar system planets. Spectroscopy of the disk ansae reveal a slightly blue to gray disk color, consistent with major Kuiper belt chemical constituents, where water-ice is a very plausible dominant constituent. Besides being the first object discovered with the next generation of extreme adaptive optics systems (i.e. SCExAO, GPI, SPHERE), HD 115600's debris ring and planetary system provides a key reference point for the early evolution of the solar system, the structure and composition of the Kuiper belt, and the interaction between debris disks and planets.

  13. Direct observations of flow path evolution during reactive transport in porous media using clinical nuclear imaging tomography

    NASA Astrophysics Data System (ADS)

    Druhan, J. L.; Finsterle, S.; Vandehey, N. T.; Boutchko, R.; O'Neil, J.; Moses, W. W.; Nico, P. S.

    2012-12-01

    Changes in the physical structure of a porous medium associated with heterogeneous reactivity are extremely difficult to observe directly. We require the ability to monitor, quantify and predict these changes in order to optimize contaminant sequestration and remediation strategies, develop carbon storage methods and preserve groundwater resources. Field-scale detection of chemically induced permeability alteration is often accomplished by multiple hydrogeophysical observations and pumping tests, whereas direct analysis of the structural changes in a porous medium are limited to small sample sizes that do not capture the range of length scales describing heterogeneity. Here we present a novel application of medical imaging techniques to directly observe variations in flow field structure associated with mineral precipitation in real time. We use a Single Photon Emission Computed Tomography (SPECT) scanner to observe the movement of a conservative 99mTc-DTPA tracer introduced to a through-flowing column of packed sediment recovered from the Old Rifle aquifer in Western Colorado. Nine individual imaging studies were carried out over the course of 112 days of continuous flow in the 30 cm long, 10 cm diameter column. During this time, organic carbon was supplied to the influent, leading to microbially mediated reduction of Fe(III) (hyrdo)oxides and sulfate. Permeability reduction associated with this reactivity is known to occur as a result of biomass accumulation and precipitation of FeS and carbonate minerals. The nine imaging datasets each yielded intensity values over a 24 hour period at a resolution of 4.42 mm3. These images were corrected for decay and attenuation to produce 4D datasets directly proportional to Tc-DTPA concentration. These data provide a highly accurate observation of the flow field during each imaging study, and are used to assign property values to the elements of a geostatistical model using the iTOUGH2 code. Permeability distributions

  14. Magnetic resonance visualization of conductive structures by sequence-triggered direct currents and spin-echo phase imaging

    SciTech Connect

    Eibofner, Frank; Wojtczyk, Hanne; Graf, Hansjörg E-mail: drGraf@t-online.de; Clasen, Stephan

    2014-06-15

    Purpose: Instrument visualization in interventional magnetic resonance imaging (MRI) is commonly performed via susceptibility artifacts. Unfortunately, this approach suffers from limited conspicuity in inhomogeneous tissue and disturbed spatial encoding. Also, susceptibility artifacts are controllable only by sequence parameters. This work presents the basics of a new visualization method overcoming such problems by applying sequence-triggered direct current (DC) pulses in spin-echo (SE) imaging. SE phase images allow for background free current path localization. Methods: Application of a sequence-triggered DC pulse in SE imaging, e.g., during a time period between radiofrequency excitation and refocusing, results in transient field inhomogeneities. Dependent on the additional z-magnetic field from the DC, a phase offset results despite the refocusing pulse. False spatial encoding is avoided by DC application during periods when read-out or slice-encoding gradients are inactive. A water phantom containing a brass conductor (water equivalent susceptibility) and a titanium needle (serving as susceptibility source) was used to demonstrate the feasibility. Artifact dependence on current strength and orientation was examined. Results: Without DC, the brass conductor was only visible due to its water displacement. The titanium needle showed typical susceptibility artifacts. Applying triggered DC pulses, the phase offset of spins near the conductor appeared. Because SE phase images are homogenous also in regions of persistent field inhomogeneities, the position of the conductor could be determined with high reliability. Artifact characteristic could be easily controlled by amperage leaving sequence parameters unchanged. For an angle of 30° between current and static field visualization was still possible. Conclusions: SE phase images display the position of a conductor carrying pulsed DC free from artifacts caused by persistent field inhomogeneities. Magnitude and phase

  15. Design and commissioning of a directly coupled in-vivo multiphoton microscope for skin imaging in humans and large animals

    NASA Astrophysics Data System (ADS)

    Mulholland, William J.; Kendall, Mark A.

    2004-02-01

    The application of near infrared multiphoton excitation to the laser-scanning microscope was first conceived by Denk, Strickler and Webb in 1990. Since then, advances in design have seen the multiphoton laser scanning microscope (MPLSM) applied to a wide range of biological research areas, including skin imaging and vaccine delivery. The technique has the attributes of low phototoxicity, high-resolution functional imaging to depths in scattered tissues. These characteristics have encouraged engineers and scientists to develop in-vivo imaging systems. For these applications, laser excitation pulses can be delivered to the sample through optical fibers. Although this solution provides a number of advantages relating to movement and flexibility of the site of interest relative to the laser source, the peak powers that can be delivered down the fiber are limited. We report on the design and commissioning of a directly coupled in-vivo MPM system, optimised for the imaging of epidermal vaccines delivered to a range of biological models and humans. Specifically, we seek to apply the system to visualise in-vivo, the influence of hand-held, helium powered needle-free systems on skin cells. A standard Nikon E600FN microscope, dissected above the optical plane was cantilevered from a vibration isolated table using rigid support arms. The modified microscope was coupled to an infrared optimised Bio-Rad Radiance 2100MP, multiphoton dedicated laser scanning control and image acquisition system. Femtosecond laser pulses were provided by a 10W Verdi pumped Mira Ti:Sapphire laser, from Coherent Inc. The microscope was modified such that the transmission half may be selectively attached for conventional imaging with ex-vivo and cell culture samples, or removed for in-vivo imaging of skin sites on the body of humans and large animals. Optical performance of the system, and aspects of its design and commissioning are discussed in this paper.

  16. Performance evaluation of four directional emissivity analytical models with thermal SAIL model and airborne images.

    PubMed

    Ren, Huazhong; Liu, Rongyuan; Yan, Guangjian; Li, Zhao-Liang; Qin, Qiming; Liu, Qiang; Nerry, Françoise

    2015-04-06

    Land surface emissivity is a crucial parameter in the surface status monitoring. This study aims at the evaluation of four directional emissivity models, including two bi-directional reflectance distribution function (BRDF) models and two gap-frequency-based models. Results showed that the kernel-driven BRDF model could well represent directional emissivity with an error less than 0.002, and was consequently used to retrieve emissivity with an accuracy of about 0.012 from an airborne multi-angular thermal infrared data set. Furthermore, we updated the cavity effect factor relating to multiple scattering inside canopy, which improved the performance of the gap-frequency-based models.

  17. MALDI-imaging enables direct observation of kinetic and thermodynamic products of mixed peptide fiber assembly.

    PubMed

    Medini, Karima; West, Brandi; Williams, David E; Brimble, Margaret A; Gerrard, Juliet A

    2017-02-04

    Controlling the self-assembly of multicomponent systems provides a key to designing new materials and understanding the molecular complexity of biology. Here, we demonstrate the first use of MALDI-imaging to characterize a multicomponent self-assembling peptide fiber. Observations of mixed peptide systems over time demonstrate how simple sequence variation can change the balance between kinetic and thermodynamic products.

  18. Magnetic resonance imaging biomarkers in patients with progressive ataxia: current status and future direction.

    PubMed

    Currie, Stuart; Hadjivassiliou, Marios; Craven, Ian J; Wilkinson, Iain D; Griffiths, Paul D; Hoggard, Nigel

    2013-04-01

    A diagnostic challenge commonly encountered in neurology is that of an adult patient presenting with ataxia. The differential is vast and clinical assessment alone may not be sufficient due to considerable overlap between different causes of ataxia. Magnetic resonance (MR)-based biomarkers such as voxel-based morphometry, MR spectroscopy, diffusion-weighted and diffusion-tensor imaging and functional MR imaging are gaining great attention for their potential as indicators of disease. A number of studies have reported correlation with clinical severity and underlying pathophysiology, and in some cases, MR imaging has been shown to allow differentiation of conditions causing ataxia. However, despite recent advances, their sensitivity and specificity vary. In addition, questions remain over their validity and reproducibility, especially when applied in routine clinical practice. This article extensively reviews the current literature regarding MR-based biomarkers for the patient with predominantly adult-onset ataxia. Imaging features characteristic of a particular ataxia are provided and features differentiating ataxia groups and subgroups are discussed. Finally, discussion will turn to the feasibility of applying these biomarkers in routine clinical practice.

  19. Direct measurement of speed of sound in cartilage in situ using ultrasound and magnetic resonance images.

    PubMed

    Nitta, N; Aoki, T; Hyodo, K; Misawa, M; Homma, K

    2013-01-01

    This study verified the accuracy of the speed of sound (SOS) measured by the combination method, which calculates the ratio between the thickness values of cartilage measured by using the magnetic resonance imaging (MRI) and the ultrasonic pulse-echo imaging, and investigated in vivo application of this method. SOS specific to an ultrasound imaging device was used as a reference value to calculate the actual SOS from the ratio of cartilage thicknesses obtained from MR and ultrasound images. The accuracy of the thickness measurement was verified by comparing results obtained using MRI and a non-contact laser, and the accuracy of the calculated SOS was confirmed by comparing results of the pulse-echo and transmission methods in vitro. The difference between laser and MRI measurements was 0.05 ± 0.22 mm. SOS values in a human knee measured by the combination method in the medial and lateral femoral condyles were 1650 ± 79 and 1642 ± 78 m/s, respectively (p < 0.05). The results revealed the feasibility of in situ SOS measurement using the combination method.

  20. Design and Verification of External Occulters for Direct Imaging of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Cady, Eric

    2011-01-01

    An occulter is an optical element which is placed in front of the telescope to block most of the light from a star before it reaches the optics inside, without blocking the planet.In our case, we use two spacecraft ying in formation: First has its edge shaped to cancel the starlight Second is the telescope which images the star and planet

  1. Direct Digital Demultiplexing of Analog TDM Signals for Cable Reduction in Ultrasound Imaging Catheters.

    PubMed

    Carpenter, Thomas M; Rashid, M Wasequr; Ghovanloo, Maysam; Cowell, David M J; Freear, Steven; Degertekin, F Levent

    2016-08-01

    In real-time catheter-based 3-D ultrasound imaging applications, gathering data from the transducer arrays is difficult, as there is a restriction on cable count due to the diameter of the catheter. Although area and power hungry multiplexing circuits integrated at the catheter tip are used in some applications, these are unsuitable for use in small sized catheters for applications, such as intracardiac imaging. Furthermore, the length requirement for catheters and limited power available to on-chip cable drivers leads to limited signal strength at the receiver end. In this paper, an alternative approach using analog time-division multiplexing (TDM) is presented, which addresses the cable restrictions of ultrasound catheters. A novel digital demultiplexing technique is also described, which allows for a reduction in the number of analog signal processing stages required. The TDM and digital demultiplexing schemes are demonstrated for an intracardiac imaging system that would operate in the 4- to 11-MHz range. A TDM integrated circuit (IC) with an 8:1 multiplexer is interfaced with a fast analog-to-digital converter (ADC) through a microcoaxial catheter cable bundle, and processed with a field-programmable gate array register-transfer level simulation. Input signals to the TDM IC are recovered with -40-dB crosstalk between the channels on the same microcoax, showing the feasibility of this system for ultrasound imaging applications.

  2. Molecular image-directed biopsies: improving clinical biopsy selection in patients with multiple tumors

    NASA Astrophysics Data System (ADS)

    Harmon, Stephanie A.; Tuite, Michael J.; Jeraj, Robert

    2016-10-01

    Site selection for image-guided biopsies in patients with multiple lesions is typically based on clinical feasibility and physician preference. This study outlines the development of a selection algorithm that, in addition to clinical requirements, incorporates quantitative imaging data for automatic identification of candidate lesions for biopsy. The algorithm is designed to rank potential targets by maximizing a lesion-specific score, incorporating various criteria separated into two categories: (1) physician-feasibility category including physician-preferred lesion location and absolute volume scores, and (2) imaging-based category including various modality and application-specific metrics. This platform was benchmarked in two clinical scenarios, a pre-treatment setting and response-based setting using imaging from metastatic prostate cancer patients with high disease burden (multiple lesions) undergoing conventional treatment and receiving whole-body [18F]NaF PET/CT scans pre- and mid-treatment. Targeting of metastatic lesions was robust to different weighting ratios and candidacy for biopsy was physician confirmed. Lesion ranked as top targets for biopsy remained so for all patients in pre-treatment and post-treatment biopsy selection after sensitivity testing was completed for physician-biased or imaging-biased scenarios. After identifying candidates, biopsy feasibility was evaluated by a physician and confirmed for 90% (32/36) of high-ranking lesions, of which all top choices were confirmed. The remaining cases represented lesions with high anatomical difficulty for targeting, such as proximity to sciatic nerve. This newly developed selection method was successfully used to quantitatively identify candidate lesions for biopsies in patients with multiple lesions. In a prospective study, we were able to successfully plan, develop, and implement this technique for the selection of a pre-treatment biopsy location.

  3. Direct microCT imaging of non-mineralized connective tissues at high resolution.

    PubMed

    Naveh, Gili R S; Brumfeld, Vlad; Dean, Mason; Shahar, Ron; Weiner, Steve

    2014-01-01

    The 3D imaging of soft tissues in their native state is challenging, especially when high resolution is required. An X-ray-based microCT is, to date, the best choice for high resolution 3D imaging of soft tissues. However, since X-ray attenuation of soft tissues is very low, contrasting enhancement using different staining materials is needed. The staining procedure, which also usually involves tissue fixation, causes unwanted and to some extent unknown tissue alterations. Here, we demonstrate that a method that enables 3D imaging of soft tissues without fixing and staining using an X-ray-based bench-top microCT can be applied to a variety of different tissues. With the sample mounted in a custom-made loading device inside a humidity chamber, we obtained soft tissue contrast and generated 3D images of fresh, soft tissues with a resolution of 1 micron voxel size. We identified three critical conditions which make it possible to image soft tissues: humidified environment, mechanical stabilization of the sample and phase enhancement. We demonstrate the capability of the technique using different specimens: an intervertebral disc, the non-mineralized growth plate, stingray tessellated radials (calcified cartilage) and the collagenous network of the periodontal ligament. Since the scanned specimen is fresh an interesting advantage of this technique is the ability to scan a specimen under load and track the changes of the different structures. This method offers a unique opportunity for obtaining valuable insights into 3D structure-function relationships of soft tissues.

  4. Molecular image-directed biopsies: improving clinical biopsy selection in patients with multiple tumors.

    PubMed

    Harmon, Stephanie A; Tuite, Michael J; Jeraj, Robert

    2016-10-21

    Site selection for image-guided biopsies in patients with multiple lesions is typically based on clinical feasibility and physician preference. This study outlines the development of a selection algorithm that, in addition to clinical requirements, incorporates quantitative imaging data for automatic identification of candidate lesions for biopsy. The algorithm is designed to rank potential targets by maximizing a lesion-specific score, incorporating various criteria separated into two categories: (1) physician-feasibility category including physician-preferred lesion location and absolute volume scores, and (2) imaging-based category including various modality and application-specific metrics. This platform was benchmarked in two clinical scenarios, a pre-treatment setting and response-based setting using imaging from metastatic prostate cancer patients with high disease burden (multiple lesions) undergoing conventional treatment and receiving whole-body [(18)F]NaF PET/CT scans pre- and mid-treatment. Targeting of metastatic lesions was robust to different weighting ratios and candidacy for biopsy was physician confirmed. Lesion ranked as top targets for biopsy remained so for all patients in pre-treatment and post-treatment biopsy selection after sensitivity testing was completed for physician-biased or imaging-biased scenarios. After identifying candidates, biopsy feasibility was evaluated by a physician and confirmed for 90% (32/36) of high-ranking lesions, of which all top choices were confirmed. The remaining cases represented lesions with high anatomical difficulty for targeting, such as proximity to sciatic nerve. This newly developed selection method was successfully used to quantitatively identify candidate lesions for biopsies in patients with multiple lesions. In a prospective study, we were able to successfully plan, develop, and implement this technique for the selection of a pre-treatment biopsy location.

  5. TU-F-18C-02: Increasing Amorphous Selenium Thickness in Direct Conversion Flat-Panel Imagers for Contrast-Enhanced Dual-Energy Breast Imaging

    SciTech Connect

    Scaduto, DA; Hu, Y-H; Zhao, W

    2014-06-15

    Purpose: Contrast-enhanced (CE) breast imaging using iodinated contrast agents requires imaging with x-ray spectra at energies greater than those used in mammography. Optimizing amorphous selenium (a-Se) flat panel imagers (FPI) for this higher energy range may increase lesion conspicuity. Methods: We compare imaging performance of a conventional FPI with 200 μm a-Se conversion layer to a prototype FPI with 300 μm a-Se layer. Both detectors are evaluated in a Siemens MAMMOMAT Inspiration prototype digital breast tomosynthesis (DBT) system using low-energy (W/Rh 28 kVp) and high-energy (W/Cu 49 kVp) x-ray spectra. Detectability of iodinated lesions in dual-energy images is evaluated using an iodine contrast phantom. Effects of beam obliquity are investigated in projection and reconstructed images using different reconstruction methods. The ideal observer signal-to-noise ratio is used as a figure-of-merit to predict the optimal a-Se thickness for CE lesion detectability without compromising conventional full-field digital mammography (FFDM) and DBT performance. Results: Increasing a-Se thickness from 200 μm to 300 μm preserves imaging performance at typical mammographic energies (e.g. W/Rh 28 kVp), and improves the detective quantum efficiency (DQE) for high energy (W/Cu 49 kVp) by 30%. While the more penetrating high-energy x-ray photons increase geometric blur due to beam obliquity in the FPI with thicker a-Se layer, the effect on lesion detectability in FBP reconstructions is negligible due to the reconstruction filters employed. Ideal observer SNR for CE objects shows improvements in in-plane detectability with increasing a-Se thicknesses, though small lesion detectability begins to degrade in oblique projections for a-Se thickness above 500 μm. Conclusion: Increasing a-Se thickness in direct conversion FPI from 200 μm to 300 μm improves lesion detectability in CE breast imaging with virtually no cost to conventional FFDM and DBT. This work was partially

  6. A new method to determine trace boron concentration of iron and steel by SIMS direct ion image

    NASA Astrophysics Data System (ADS)

    Kim, JaeNam; Lee, SangUp; Kwun, HyeogDae; Kim, JoonWon; Shin, KwangSoo; Lee, JungJu

    2012-04-01

    Boron is often used as a trace additive in steel in order to control the phase transformation behaviors and improve the interfacial cohesion. The aim of this work is to suggest a method to determine the trace boron concentration of iron and steel by direct ion image. The optimum conditions for direct ion imaging were proposed by means of secondary ion mass spectrometry — resistive anode encorder (SIMS-RAE). A method of quantification was examined using standard reference materials, electrolytic iron, high carbon steel, Cr-V steel and stainless steel. For the best secondary ionization efficiency, O2 + ion bombardment and negative secondary ion collection were used. The cluster ions of 11B16O2 and 56Fe16O were detected and processed to reduce the strong matrix effect. Every pixel, P(i, j) of 50 images was integrated and converted to a retrospective depth profile by calculator and profiler. The calibration curve and relative sensitivity factor (RSF) approach were considered. Furthermore, reproducibility of the SIMS data depending on the analytical mode was examined.

  7. Microcoil-based MR phase imaging and manganese enhanced microscopy of glial tumor neurospheres with direct optical correlation.

    PubMed

    Baxan, Nicoleta; Kahlert, Ulf; Maciaczyk, Jaroslaw; Nikkhah, Guido; Hennig, Jürgen; von Elverfeldt, Dominik

    2012-07-01

    Susceptibility differences among tissues were recently used for highlighting complementary contrast in MRI different from the conventional T(1), T(2), or spin density contrasts. This method, based on the signal phase, previously showed improved image contrast of human or rodent neuroarchitecture in vivo, although direct MR phase imaging of cellular architecture was not available until recently. In this study, we present for the first time the ability of microcoil-based phase MRI to resolve the structure of human glioma neurospheres at significantly improved resolutions (10 × 10 μm(2)) with direct optical image correlation. The manganese chloride property to function as a T(1) contrast agent enabled a closer examination of cell physiology with MRI. Specifically the temporal changes of manganese chloride uptake, retention and release time within and from individual clusters were assessed. The optimal manganese chloride concentration for improved MR signal enhancement was determined while keeping the cellular viability unaffected. The presented results demonstrate the possibilities to reveal structural and functional observation of living glioblastoma human-derived cells. This was achieved through the combination of highly sensitive microcoils, high magnetic field, and methods designed to maximize contrast to noise ratio. The presented approach may provide a powerful multimodal tool that merges structural and functional information of submilimeter biological samples.

  8. Robust approximation of image illumination direction in a segmentation-based crater detection algorithm for spacecraft navigation

    NASA Astrophysics Data System (ADS)

    Maass, Bolko

    2016-12-01

    This paper describes an efficient and easily implemented algorithmic approach to extracting an approximation to an image's dominant projected illumination direction, based on intermediary results from a segmentation-based crater detection algorithm (CDA), at a computational cost that is negligible in comparison to that of the prior stages of the CDA. Most contemporary CDAs built for spacecraft navigation use this illumination direction as a means of improving performance or even require it to function at all. Deducing the illumination vector from the image alone reduces the reliance on external information such as the accurate knowledge of the spacecraft inertial state, accurate time base and solar system ephemerides. Therefore, a method such as the one described in this paper is a prerequisite for true "Lost in Space" operation of a purely segmentation-based crater detecting and matching method for spacecraft navigation. The proposed method is verified using ray-traced lunar elevation model data, asteroid image data, and in a laboratory setting with a camera in the loop.

  9. 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 GERMAN TerraSAR-X mission was launched in June 2007, operating a versatile new-generation SAR sensor in X-band. Its Spotlight mode providing SAR images at very high resolution of about 1m. The product’s specified 3-D geolocation accuracy is tightened to 1m according to the official technical report. However, this accuracy is able to be achieved relies on not only robust mathematical basis of SAR geolocation, but also well knowledge of error sources and their correction. The research focuses on geolocation of TerraSAR-X spotlight image. Mathematical model and resolving algorithms have been analyzed. Several error sources have been researched and corrected especially. The effectiveness and accuracy of the research was verified by the experiment results.

  10. Direct estimation of aberrating delays in pulse-echo imaging systems.

    PubMed

    Rachlin, D

    1990-07-01

    Nearfield fluctuations in wave propagation velocity and system timing errors are among the sources of focusing aberrations in pulse-echo imaging systems. For situations in which the source of these errors can be modeled by a stationary phase aberrator placed in front of the transmitter and receiver aperture, appropriate electronic delays might be applied to the signals associated with each array element in order to restore the system to focus. A method is described and evaluated for estimating the set of aberrating delays in a linear array utilizing data from a single two-dimensional scan. The underlying principle is analogous to that of phase closure used for one-way passive interferometry and readily generalizes to two-dimensional arrays. Although the following theory is developed in the context of acoustic imaging, the general approach is applicable to other pulse-echo systems, such as radar.

  11. Direct, trans-irradiation and multispectral infrared imaging of a Titian canvas

    NASA Astrophysics Data System (ADS)

    Daffara, Claudia; Monti, Francesca; Fontana, Raffaella; Artoni, Paola; Salvadori, Ornella

    2013-05-01

    Near infrared imaging is a powerful technique for the analysis of ancient paintings, allowing the nondestructive examination of features underneath the pictorial surface. Beyond the unique nature of the artwork (materials and layer stratigraphy), the effectiveness of the technique in detecting any painting features is determined by the device performance (spectral sensitivity, acquisition band narrowness, spatial resolution) as well as by the irradiation setup. We performed multi-modal infrared imaging on a XVI century masterpiece by Titian using an InGaAs camera and different measurement setup. Acquisition was carried out in conventional reflection geometry and in trans-irradiation mode, as well as in wideband and multispectral modes. Preliminary results are presented and the potentialities of such infrared analysis discussed.

  12. Direct imaging of molecular symmetry by coherent anti-stokes Raman scattering

    PubMed Central

    Cleff, Carsten; Gasecka, Alicja; Ferrand, Patrick; Rigneault, Hervé; Brasselet, Sophie; Duboisset, Julien

    2016-01-01

    Nonlinear optical methods, such as coherent anti-Stokes Raman scattering and stimulated Raman scattering, are able to perform label-free imaging, with chemical bonds specificity. Here we demonstrate that the use of circularly polarized light allows to retrieve not only the chemical nature but also the symmetry of the probed sample, in a single measurement. Our symmetry-resolved scheme offers simple access to the local organization of vibrational bonds and as a result provides enhanced image contrast for anisotropic samples, as well as an improved chemical selectivity. We quantify the local organization of vibrational bonds on crystalline and biological samples, thus providing information not accessible by spontaneous Raman and stimulated Raman scattering techniques. This work stands for a symmetry-resolved contrast in vibrational microscopy, with potential application in biological diagnostic. PMID:27189667

  13. Future directions in 3-dimensional imaging and neurosurgery: stereoscopy and autostereoscopy.

    PubMed

    Christopher, Lauren A; William, Albert; Cohen-Gadol, Aaron A

    2013-01-01

    Recent advances in 3-dimensional (3-D) stereoscopic imaging have enabled 3-D display technologies in the operating room. We find 2 beneficial applications for the inclusion of 3-D imaging in clinical practice. The first is the real-time 3-D display in the surgical theater, which is useful for the neurosurgeon and observers. In surgery, a 3-D display can include a cutting-edge mixed-mode graphic overlay for image-guided surgery. The second application is to improve the training of residents and observers in neurosurgical techniques. This article documents the requirements of both applications for a 3-D system in the operating room and for clinical neurosurgical training, followed by a discussion of the strengths and weaknesses of the current and emerging 3-D display technologies. An important comparison between a new autostereoscopic display without glasses and current stereo display with glasses improves our understanding of the best applications for 3-D in neurosurgery. Today's multiview autostereoscopic display has 3 major benefits: It does not require glasses for viewing; it allows multiple views; and it improves the workflow for image-guided surgery registration and overlay tasks because of its depth-rendering format and tools. Two current limitations of the autostereoscopic display are that resolution is reduced and depth can be perceived as too shallow in some cases. Higher-resolution displays will be available soon, and the algorithms for depth inference from stereo can be improved. The stereoscopic and autostereoscopic systems from microscope cameras to displays were compared by the use of recorded and live content from surgery. To the best of our knowledge, this is the first report of application of autostereoscopy in neurosurgery.

  14. One mirror beam steering: determination of steering mirror parameters from image pointing direction

    NASA Astrophysics Data System (ADS)

    Andersen, Torben B.; Granger, Zachary A.

    2016-09-01

    Mathematical models are used to establish the exact path of a beam reflected by a plane mirror in terms of the mirror geometry descriptors. In particular, the mirror geometry descriptors (tilt angles) are determined as functions of the beam path in image space. This is also useful for determining scan patterns when the mirror is used as a scanning device. These formulations are readily adaptable to commercially available ray tracing programs.

  15. Investigation of a one-step spectral CT reconstruction algorithm for direct inversion into basis material images

    NASA Astrophysics Data System (ADS)

    Gilat Schmidt, Taly; Sidky, Emil Y.

    2015-03-01

    Photon-counting detectors with pulse-height analysis have shown promise for improved spectral CT imaging. This study investigated a novel spectral CT reconstruction method that directly estimates basis-material images from the measured energy-bin data (i.e., `one-step' reconstruction). The proposed algorithm can incorporate constraints to stabilize the reconstruction and potentially reduce noise. The algorithm minimizes the error between the measured energy-bin data and the data estimated from the reconstructed basis images. A total variation (TV) constraint was also investigated for additional noise reduction. The proposed one-step algorithm was applied to simulated data of an anthropomorphic phantom with heterogeneous tissue composition. Reconstructed water, bone, and gadolinium basis images were compared for the proposed one-step algorithm and the conventional `two-step' method of decomposition followed by reconstruction. The unconstrained algorithm provided a 30% to 60% reduction in noise standard deviation compared to the two-step algorithm. The fTV =0.8 constraint provided a small reduction in noise (˜ 1%) compared to the unconstrained reconstruction. Images reconstructed with the fTV =0.5 constraint demonstrated 77% to 94% standard deviation reduction compared to the two-step reconstruction, however with increased blurring. There were no significant differences in the mean values reconstructed by the investigated algorithms. Overall, the proposed one-step spectral CT reconstruction algorithm provided three-material-decomposition basis images with reduced noise compared to the conventional two-step approach. When using a moderate TV constraint factor (fTV = 0.8), a 30%-60% reduction in noise standard deviation was achieved while preserving the edge profile for this simulated phantom.

  16. Direct imaging of planetary systems with a ground-based radio telescope array

    NASA Technical Reports Server (NTRS)

    Jones, Dayton L.

    1994-01-01

    The National Radio Astronomy Observatory's proposed Millimeter Array (MMA) will bring unprecedented sensitivity, angular resolution, and image dynamic range to the millimeter wavelength region of the spectrum. An obvious question is whether such an instrument could be used to detect planets orbiting nearby stars. The techniques of aperture synthesis imaging developed for centimeter wavelength radio arrays are capable of producing images whose dynamic ranges greatly exceed the brightness ratio of a solar-type star and a Jupiter-like planet at sub-millimeter or millimeter wavelengths. The angular resolution required to separate a star and planet at a few pc distance can be obtained with baselines of several km. The greatest challenge is sensitivity. At the highest possible observing frequencies (approximately 300 GHz for typical high, dry sites, and approximately 900 GHz from the Antarctic plateau), the proposed MMA will be unable to detect the thermal emission from a Jupiter-like planet a few pc away. An upgraded MMA operating near 300 GHz with twice the currently proposed number of antennas, a 20% fractional bandwidth, and improved receivers could detect Jupiter at 4 pc in a few months. Building such an array on the Antarctic plateau and operating at approximately 900 GHz would allow Jupiter at 4 pc to be detected in approximately one day of observing time.

  17. Probe-Scale Mission Concepts for Direct Imaging and Spectroscopy of Nearby Exoplanet Systems

    NASA Astrophysics Data System (ADS)

    Unwin, Stephen C.; Seager, Sara; Stapelfeldt, Karl R.; Warfield, Keith; Dekens, Frank G.; Blackwood, Gary; Exo-S Science; Technology Definition Team, Exo-C Science; Technology Definition Team, JPL Probe Study Design Teams

    2015-01-01

    Two mission concepts are now under study for detecting visible light from exoplanets orbiting nearby stars through high-contrast imaging and for characterizing them through spectroscopy. Exo-S uses a starshade (external occulter) that flies in front of a telescope to block out the central starlight; Exo-C uses a coronagraph with an internal occulter to accomplish the suppression of starlight. Both concepts have the objective of taking optical spectra of nearby exoplanets in reflected light, searching for previously undetected planets, and imaging structure in circumstellar debris disks.The concepts are being developed by two NASA-selected community-led Science and Technology Definition Teams (STDTs), supported by study design teams from NASA's Exoplanet Exploration Program. In addition to developing concepts with an estimated cost ~1B, the Teams are identifying key enabling technologies needed for their designs. These concepts complement existing NASA missions that do exoplanet science (such as transit spectroscopy and debris disk imaging with HST and Spitzer) or are under development or active study (TESS, JWST, WFIRST-AFTA).Final Reports from the two studies will be published in early 2015. This poster serves as an introduction to a series of posters featuring the two studies. At the conclusion of the studies in early 2015, NASA will evaluate them for further technology development and possible development as flight missions. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  18. Simple Nanoimprinted Polymer Nanostructures for Uncooled Thermal Detection by Direct Surface Plasmon Resonance Imaging.

    PubMed

    Hong, Brandon; Vallini, Felipe; Fang, Cheng-Yi; Alasaad, Amr; Fainman, Yeshaiahu

    2017-03-08

    We experimentally demonstrate the uncooled detection of long wavelength infrared (IR) radiation by thermal surface plasmon sensing using an all optical readout format. Thermal infrared radiation absorbed by an IR-sensitive material with high thermo-optic coefficient coated on a metal grating creates a refractive index change detectable by the shift of the supported surface plasmon resonance (SPR) measured optically in the visible spectrum. The interface localization of SPR modes and optical readout allow for submicrometer thin film transducers and eliminate complex readout integrated circuits, respectively, reducing form factor, leveraging robust visible detectors, and enabling low-cost imaging cameras. We experimentally present the radiative heat induced thermo-optic action detectable by SPR shift through imaging of a thermal source onto a bulk metal grating substrate with IR-absorptive silicon nitride coating. Toward focal plane array integration, a route to facile fabrication of pixelated metal grating structures by nanoimprint lithography is developed, where a stable polymer, parylene-C, serves as an IR-absorptive layer with a high thermo-optic coefficient. Experimental detection of IR radiation from real thermal sources imaged at infinity is demonstrated by our nanoimprinted polymer-SPR pixels with an estimated noise equivalent temperature difference of 21.9 K.

  19. Imaging-Genetics in Autism Spectrum Disorder: Advances, Translational Impact, and Future Directions

    PubMed Central

    Ameis, Stephanie H.; Szatmari, Peter

    2012-01-01

    Autism Spectrum Disorder (ASD) refers to a group of heterogeneous neurodevelopmental disorders that are unified by impairments in reciprocal social communication and a pattern of inflexible behaviors. Recent genetic advances have resolved some of the complexity of the genetic architecture underlying ASD by identifying several genetic variants that contribute to the disorder. Different etiological pathways associated with ASD may converge through effects on common molecular mechanisms, such as synaptogenesis, neuronal motility, and axonal guidance. Recently, with more sophisticated techniques, neuroimaging, and neuropathological studies have provided some consistency of evidence that altered structure, activity, and connectivity within complex neural networks is present in ASD, compared to typically developing children. The imaging-genetics approach promises to help bridge the gap between genetic variation, resultant biological effects on the brain, and production of complex neuropsychiatric symptoms. Here, we review recent findings from the developing field of imaging-genetics applied to ASD. Studies to date have indicated that relevant risk genes are associated with alterations in circuits that mediate socio-emotional, visuo-spatial, and language processing. Longitudinal studies ideally focused on early development, in conjunction with investigation for gene–gene, and gene–environment interactions may move the promise of imaging-genetics in ASD closer to the clinical domain. PMID:22615702

  20. Image quality evaluation of direct-conversion digital mammography system with new dual a-Se layer detector

    NASA Astrophysics Data System (ADS)

    Kuwabara, Takao; Iwasaki, Nobuyuki; Sendai, Tomonari; Furue, Ryosuke; Agano, Toshitaka

    2009-02-01

    To increase the detection performance of breast cancers in mammograms, we need to improve shape delineation of micro calcifications and tumors. We accomplished this by developing a direct-conversion mammography system with an optical reading method and a new dual a-Se layer detector. The system achieved both small pixel size (50 micrometer) and a high Detective Quantum Efficiency (DQE) realized by 100 % of fill factor and noise reduction. We evaluated image quality performance and determined the best exposure conditions. We measured DQE and Modulation Transfer Function(MTF) according to the IEC62220-1-2. High DQE was maintained at a low radiation dosage, indicating that the optical reading method accompanies low noises. Response of MTF was maintained at up to the Nyquist frequency of 10 cyc/mm, which corresponds to 50 micrometer pixel size. To determine the best exposure conditions, we measured Contrast to Noise Ratio (CNR) and visually evaluated images of a resected breast under conditions of MoMo, MoRh, and WRh. There were occasional disagreements between the exposure conditions for achieving the maximum CNR and those for the best image graded by the visual evaluation. This was probably because CNR measurement does not measure effects of scattered X-ray. The images verified the improvement in detection and delineation performance of micro calcifications and tumors.

  1. Direct Visualization of Neurotransmitters in Rat Brain Slices by Desorption Electrospray Ionization Mass Spectrometry Imaging (DESI - MS)

    NASA Astrophysics Data System (ADS)

    Fernandes, Anna Maria A. P.; Vendramini, Pedro H.; Galaverna, Renan; Schwab, Nicolas V.; Alberici, Luciane C.; Augusti, Rodinei; Castilho, Roger F.; Eberlin, Marcos N.

    2016-12-01

    Mass spectrometry imaging (MSI) of neurotransmitters has so far been mainly performed by matrix-assisted laser desorption/ionization (MALDI) where derivatization reagents, deuterated matrix and/or high resolution, or tandem MS have been applied to circumvent problems with interfering ion peaks from matrix and from isobaric species. We herein describe the application of desorption electrospray ionization mass spectrometry imaging (DESI)-MSI in rat brain coronal and sagittal slices for direct spatial monitoring of neurotransmitters and choline with no need of derivatization reagents and/or deuterated materials. The amino acids γ-aminobutyric (GABA), glutamate, aspartate, serine, as well as acetylcholine, dopamine, and choline were successfully imaged using a commercial DESI source coupled to a hybrid quadrupole-Orbitrap mass spectrometer. The spatial distribution of the analyzed compounds in different brain regions was determined. We conclude that the ambient matrix-free DESI-MSI is suitable for neurotransmitter imaging and could be applied in studies that involve evaluation of imbalances in neurotransmitters levels.

  2. The impact of filtering direct-feedthrough on the x-space theory of magnetic particle imaging

    NASA Astrophysics Data System (ADS)

    Lu, Kuan; Goodwill, Patrick; Zheng, Bo; Conolly, Steven

    2011-03-01

    Magnetic particle imaging (MPI) is a new medical imaging modality that maps the instantaneous response of superparamagnetic particles under an applied magnetic field. In MPI, the excitation and detection of the nanoparticles occur simultaneously. Therefore, when a sinusoidal excitation field is applied to the system, the received signal spectrum contains both harmonics from the particles and a direct feedthrough signal from the source at the fundamental drive frequency. Removal of the induced feedthrough signal from the received signal requires significant filtering, which also removes part of the signal spectrum. In this paper, we present a method to investigate the impact of temporally filtering out individual lower order harmonics on the reconstructed x-space image. Analytic and simulation results show that the loss of particle signal at low frequency leads to a recoverable loss of low spatial frequency information in the x-space image. Initial experiments validate the findings and demonstrate the feasibility of the recovery of the lost signal. This builds on earlier work that discusses the ideal one-dimensional MPI system and harmonic decomposition of the MPI signal.

  3. Report of an image quality and dose audit according to directive 97/43/Euratom at Spanish private radiodiagnostics facilities.

    PubMed

    González, L; Vañó, E; Oliete, S; Manrique, J; Hernáez, J M; Lahuerta, J; Ruiz, J

    1999-02-01

    An audit of Spanish private medicine radiodiagnostics facilities has been carried out, based partly on Spanish legislation relating to European Directives on health protection against ionizing radiation risks in medical exposure. The study included an appraisal of infrastructure and equipment, and aspects of quality assurance and radiation protection, by means of data collected through surveys. Of the 51 centres audited, a sample of 24 X-ray rooms was chosen, then an external evaluation with regard to image quality and patient dose was performed, by an advisory board of radiologists and medical physicists. The methodology used was similar to that of the group of European Union experts in European dose evaluation and image quality trials. Chest, abdomen, lumbar spine and breast examinations were monitored. Doses were measured with thermoluminescent dosimeters. A third of the X-ray rooms evaluated reached or exceeded dose reference values, and in a third of the cases the image quality left considerable room for improvement. Breast and chest examinations showed themselves to be the hardest to perform, not only as a result of exceeding the reference doses, but also due to failure to meet good image quality standards.

  4. Direct Visualization of Neurotransmitters in Rat Brain Slices by Desorption Electrospray Ionization Mass Spectrometry Imaging (DESI - MS).

    PubMed

    Fernandes, Anna Maria A P; Vendramini, Pedro H; Galaverna, Renan; Schwab, Nicolas V; Alberici, Luciane C; Augusti, Rodinei; Castilho, Roger F; Eberlin, Marcos N

    2016-12-01

    Mass spectrometry imaging (MSI) of neurotransmitters has so far been mainly performed by matrix-assisted laser desorption/ionization (MALDI) where derivatization reagents, deuterated matrix and/or high resolution, or tandem MS have been applied to circumvent problems with interfering ion peaks from matrix and from isobaric species. We herein describe the application of desorption electrospray ionization mass spectrometry imaging (DESI)-MSI in rat brain coronal and sagittal slices for direct spatial monitoring of neurotransmitters and choline with no need of derivatization reagents and/or deuterated materials. The amino acids γ-aminobutyric (GABA), glutamate, aspartate, serine, as well as acetylcholine, dopamine, and choline were successfully imaged using a commercial DESI source coupled to a hybrid quadrupole-Orbitrap mass spectrometer. The spatial distribution of the analyzed compounds in different brain regions was determined. We conclude that the ambient matrix-free DESI-MSI is suitable for neurotransmitter imaging and could be applied in studies that involve evaluation of imbalances in neurotransmitters levels. Graphical Abstract ᅟ.

  5. Automated image registration in semiconductor industry: a case study in the direct-to-digital holography inspection system

    NASA Astrophysics Data System (ADS)

    Dai, X. L.; Hunt, Martin A.

    2003-05-01

    Automated image registration based on pattern recognition is a critical procedure in many applications of machine vision and is essential for accurate navigation and change detection. In this paper, an overview of the specific applications of image registration in wafer inspection is given, followed by a case study in the application of image registration for direct to digital holography (DDH) wafer inspection. A complete system of novel algorithms for holographic image capable of accepting a variety of data streams as inputs: (1) complex frequency data; (2) complex spatial data; (3) magnitude of data extracted from holograms; (4) phase data extracted from holograms; and (5) intensity-only data. This flexibility facilitates the development of faster, more reliable, and more efficient DDH processing systems, which is important in system optimization and production. In particular, the system enables the use of the full complex wavefront, which contains both reflectance and structural topology information, in the registration process. The added information contained in the wavefront can be utilized for increased robustness and computational efficiency. Both the theory and implementation of the proposed registration system are briefly described within the framework of DDH processing for wafer inspection tasks. Several examples of defect detection and wafer alignment are given with estimates of accuracy and robustness.

  6. Matrix-assisted laser desorption/ionization imaging mass spectrometry for direct measurement of clozapine in rat brain tissue.

    PubMed

    Hsieh, Yunsheng; Casale, Roger; Fukuda, Elaine; Chen, Jiwen; Knemeyer, Ian; Wingate, Julia; Morrison, Richard; Korfmacher, Walter

    2006-01-01

    Matrix-assisted laser desorption/ionization hyphenated with quadrupole time-of-flight (QTOF) mass spectrometry (MS) has been used to directly determine the distribution of pharmaceuticals in rat brain tissue slices which might unravel their disposition for new drug development. Clozapine, an antipsychotic drug, and norclozapine were used as model compounds to investigate fundamental parameters such as matrix and solvent effects and irradiance dependence on MALDI intensity but also to address the issues with direct tissue imaging MS technique such as (1) uniform coating by the matrix, (2) linearity of MALDI signals, and (3) redistribution of surface analytes. The tissue sections were coated with various matrices on MALDI plates by airspray deposition prior to MS detection. MALDI signals of analytes were detected by monitoring the dissociation of the individual protonated molecules to their predominant MS/MS product ions. The matrices were chosen for tissue applications based on their ability to form a homogeneous coating of dense crystals and to yield greater sensitivity. Images revealing the spatial localization in tissue sections using MALDI-QTOF following a direct infusion of (3)H-clozapine into rat brain were found to be in good correlation with those using a radioautographic approach. The density of clozapine and its major metabolites from whole brain homogenates was further confirmed using fast high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) procedures.

  7. Visualization of Water Behavior in the In-plane and Throughplane Directions in a PEFC using a Neutron Image Intensifier

    NASA Astrophysics Data System (ADS)

    Murakawa, H.; Sugimoto, K.; Miyata, K.; Asano, H.; Takenaka, N.; Saito, Y.

    Water distributions of a polymer electrolyte fuel cell (PEFC) with 9-parallel channels during operation were visualized using a neutron radiography facility at B4 port in KUR (Kyoto University Research Reactor). An imaging system with a neutron image intensifier (I.I.) was employed for reducing the exposure time, and the water distributions in the in-plane and through-plane directions in the PEFC were alternately obtained every 20 sec. The accumulation processes from the GDL to the channels were confirmed. Water accumulated in the GDL at the cathode and evacuation into the channels started around 5 min. Water tended to accumulate at the edge of the ribs, and accumulated as water drops in the channels. The size of the water drops grew up to 1 mm which was the same size as the channel width and height, and the cell voltage was decreased because the liquid drops disturbed the air supply.

  8. Direct imaging of hot spots in Bi2Sr2CaCu2O8+δ mesa terahertz sources

    NASA Astrophysics Data System (ADS)

    Benseman, T. M.; Koshelev, A. E.; Kwok, W.-K.; Welp, U.; Vlasko-Vlasov, V. K.; Kadowaki, K.; Minami, H.; Watanabe, C.

    2013-04-01

    Stacks of intrinsic Josephson junctions (IJJs) made from high-temperature superconductors such as Bi2Sr2CaCu2O8+δ (Bi-2212) (BSCCO) are a promising source of coherent continuous-wave terahertz radiation. It is thought that at electrical bias conditions under which THz-emission occurs, hot spots may form due to resistive self-heating, and that these spots may be highly beneficial for the generation of high levels of THz power. Here, we perform an imaging study of the temperature distribution at the surface of BSCCO stacks utilizing the temperature-dependent 612 nm fluorescence line of Eu3+ in a europium chelate. The images directly reveal a highly non-uniform temperature distribution in which the temperature in the middle of the stack can exceed the superconducting transition temperature by tens of Kelvin under biasing conditions typical for THz-emission.

  9. X-ray self-emission imaging used to diagnose 3-D nonuniformities in direct-drive ICF implosions

    NASA Astrophysics Data System (ADS)

    Davis, A. K.; Michel, D. T.; Craxton, R. S.; Epstein, R.; Hohenberger, M.; Mo, T.; Froula, D. H.

    2016-11-01

    As hydrodynamics codes develop to increase understanding of three-dimensional (3-D) effects in inertial confinement fusion implosions, diagnostics must adapt to evaluate their predictive accuracy. A 3-D radiation postprocessor was developed to investigate the use of soft x-ray self-emission images of an imploding target to measure the size of nonuniformities on the target surface. Synthetic self-emission images calculated from 3-D simulations showed a narrow ring of emission outside the ablation surface of the target. Nonuniformities growing in directions perpendicular to the diagnostic axis were measured through angular variations in the radius of the steepest intensity gradient on the inside of the ring and through changes in the peak x-ray intensity in the ring as a function of angle. The technique was applied to an implosion to measure large 3-D nonuniformities resulting from two dropped laser beam quads at the National Ignition Facility.

  10. X-ray self-emission imaging used to diagnose 3-D nonuniformities in direct-drive ICF implosions.

    PubMed

    Davis, A K; Michel, D T; Craxton, R S; Epstein, R; Hohenberger, M; Mo, T; Froula, D H

    2016-11-01

    As hydrodynamics codes develop to increase understanding of three-dimensional (3-D) effects in inertial confinement fusion implosions, diagnostics must adapt to evaluate their predictive accuracy. A 3-D radiation postprocessor was developed to investigate the use of soft x-ray self-emission images of an imploding target to measure the size of nonuniformities on the target surface. Synthetic self-emission images calculated from 3-D simulations showed a narrow ring of emission outside the ablation surface of the target. Nonuniformities growing in directions perpendicular to the diagnostic axis were measured through angular variations in the radius of the steepest intensity gradient on the inside of the ring and through changes in the peak x-ray intensity in the ring as a function of angle. The technique was applied to an implosion to measure large 3-D nonuniformities resulting from two dropped laser beam quads at the National Ignition Facility.

  11. Directly imaged L-T transition exoplanets in the mid-infrared {sup ,}

    SciTech Connect

    Skemer, Andrew J.; Hinz, Philip M.; Morzinski, Katie M.; Leisenring, Jarron M.; Close, Laird M.; Bailey, Vanessa P.; Defrere, Denis; Follette, Katherine B.; Males, Jared R.; Rodigas, Timothy J.; Marley, Mark S.; Skrutskie, Michael F.; Saumon, Didier; Briguglio, Runa; Esposito, Simone; Puglisi, Alfio; Xompero, Marco; Hill, John M.

    2014-09-01

    Gas-giant planets emit a large fraction of their light in the mid-infrared (≳3 μm), where photometry and spectroscopy are critical to our understanding of the bulk properties of extrasolar planets. Of particular importance are the L- and M-band atmospheric windows (3-5 μm), which are the longest wavelengths currently accessible to ground-based, high-contrast imagers. We present binocular LBT adaptive optics (AO) images of the HR 8799 planetary system in six narrow-band filters from 3 to 4 μm, and a Magellan AO image of the 2M1207 planetary system in a broader 3.3 μm band. These systems encompass the five known exoplanets with luminosities consistent with L → T transition brown dwarfs. Our results show that the exoplanets are brighter and have shallower spectral slopes than equivalent temperature brown dwarfs in a wavelength range that contains the methane fundamental absorption feature (spanned by the narrow-band filters and encompassed by the broader 3.3 μm filter). For 2M1207 b, we find that thick clouds and non-equilibrium chemistry caused by vertical mixing can explain the object's appearance. For the HR 8799 planets, we present new models that suggest the atmospheres must have patchy clouds, along with non-equilibrium chemistry. Together, the presence of a heterogeneous surface and vertical mixing presents a picture of dynamic planetary atmospheres in which both horizontal and vertical motions influence the chemical and condensate profiles.

  12. Direct optical imaging and flux mapping of CH4 in landscapes

    NASA Astrophysics Data System (ADS)

    Gålfalk, M.; Olofsson, G.; Crill, P. M.; Bastviken, D.

    2014-12-01

    Methane (CH4) is a very potent greenhouse gas with many and diverse natural and anthropogenic emission sources such as wetlands, animals, biogas production, waste and sewage management systems. It has increased 2.5-fold since 1750 and is expected to continue to rise, with possible large implications for future climates. Although many individual sources have unknown fluxes, and distributions could be both hotspots or continuous, measurements are mostly made on either a very small scale (chambers or flux towers) with point-like or uncertain footprints, or on the very large scale of satellites with km-sized footprints. There is thus a missing intermediate scale, a scale which would allow both pin-pointing of individual CH4 emission sources and mapping a large enough area to cover a whole landscape. A general such method would be beneficial for connecting scattered local measurements and integrated large scale estimates. Remote sensing is a tool that is often used to map surface materials and the atmosphere from space. This technique, optimized for ground-based or near-ground, sensitive CH4 detection using high spectral resolution, could be a future method for detecting and mapping CH4 sources and fluxes in the environment. We present a new camera system with the ability to both detect and quantify CH4 at low levels in landscapes using remote sensing. Detection is made through thermal infrared (IR) imaging spectroscopy, using the heat radiation of objects in a scene to provide background light (e.g. tree leaves, rocks, grass or the sky). Using spectroscopic and radiative transfer modelling for each pixel (spectrum) in an image, we can calculate a CH4 distribution map from the measured spectra. The system uses imaging at high frequency (hundreds of Hz) to build the spectra - this also enables us to make simultaneous CH4 flux movies that can be used to calculate flows. Our method has broad applications and we will present examples from different environments.

  13. Whole-body direct 4D parametric PET imaging employing nested generalized Patlak expectation-maximization reconstruction

    NASA Astrophysics Data System (ADS)

    Karakatsanis, Nicolas A.; Casey, Michael E.; Lodge, Martin A.; Rahmim, Arman; Zaidi, Habib

    2016-08-01

    Whole-body (WB) dynamic PET has recently demonstrated its potential in translating the quantitative benefits of parametric imaging to the clinic. Post-reconstruction standard Patlak (sPatlak) WB graphical analysis utilizes multi-bed multi-pass PET acquisition to produce quantitative WB images of the tracer influx rate K i as a complimentary metric to the semi-quantitative standardized uptake value (SUV). The resulting K i images may suffer from high noise due to the need for short acquisition frames. Meanwhile, a generalized Patlak (gPatlak) WB post-reconstruction method had been suggested to limit K i bias of sPatlak analysis at regions with non-negligible 18F-FDG uptake reversibility; however, gPatlak analysis is non-linear and thus can further amplify noise. In the present study, we implemented, within the open-source software for tomographic image reconstruction platform, a clinically adoptable 4D WB reconstruction framework enabling efficient estimation of sPatlak and gPatlak images directly from dynamic multi-bed PET raw data with substantial noise reduction. Furthermore, we employed the optimization transfer methodology to accelerate 4D expectation-maximization (EM) convergence by nesting the fast image-based estimation of Patlak parameters within each iteration cycle of the slower projection-based estimation of dynamic PET images. The novel gPatlak 4D method was initialized from an optimized set of sPatlak ML-EM iterations to facilitate EM convergence. Initially, realistic simulations were conducted utilizing published 18F-FDG kinetic parameters coupled with the XCAT phantom. Quantitative analyses illustrated enhanced K i target-to-background ratio (TBR) and especially contrast-to-noise ratio (CNR) performance for the 4D versus the indirect methods and static SUV. Furthermore, considerable convergence acceleration was observed for the nested algorithms involving 10-20 sub-iterations. Moreover, systematic reduction in K i % bias and improved TBR were

  14. Amorphous and polycrystalline photoconductors for direct conversion flat panel x-ray image sensors.

    PubMed

    Kasap, Safa; Frey, Joel B; Belev, George; Tousignant, Olivier; Mani, Habib; Greenspan, Jonathan; Laperriere, Luc; Bubon, Oleksandr; Reznik, Alla; DeCrescenzo, Giovanni; Karim, Karim S; Rowlands, John A

    2011-01-01

    In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI(2) and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been

  15. Amorphous and Polycrystalline Photoconductors for Direct Conversion Flat Panel X-Ray Image Sensors

    PubMed Central

    Kasap, Safa; Frey, Joel B.; Belev, George; Tousignant, Olivier; Mani, Habib; Greenspan, Jonathan; Laperriere, Luc; Bubon, Oleksandr; Reznik, Alla; DeCrescenzo, Giovanni; Karim, Karim S.; Rowlands, John A.

    2011-01-01

    In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI2 and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been

  16. Self-assembly and structure of directly imaged inorganic-anion monolayers on a gold nanoparticle.

    PubMed

    Wang, Yifeng; Neyman, Alevtina; Arkhangelsky, Elizabeth; Gitis, Vitaly; Meshi, Louisa; Weinstock, Ira A

    2009-12-02

    Cryogenic "trapping" was used to obtain the first TEM images of self-assembled monolayers of inorganic anions on a gold nanoparticle. This unique structural information makes it possible to study the formation of a protecting-ligand shell at an unprecedented level of detail. The protecting ligands are polyoxometalates (POMs; alpha-X(n+)W(12)O(40)((8-n)-), X(n+) = Al(3+) and "2H(+)", and alpha-X(n+)W(11)O(39)((12-n)-), X(n+) = P(5+), Si(4+), and Al(3+)) with large negative charges for association with the gold surface and W atoms (Z = 74) for TEM imaging. The POM-anion shells were obtained by ligand exchange from citrate-protected 13.8 nm gold nanoparticles. Replacement of the organic (citrate) by inorganic (tungsten-oxide) ligand shells results in substantial changes in the surface plasmon resonance (SPR). By correlating cryo-TEM images with changes in the SPR, degrees of surface coverage were reliably quantified by UV-visible spectroscopy. Then, the kinetics and thermodynamics of ligand-shell formation were investigated by systematically varying POM structure and charge. Rates of POM association with the gold surface ("nucleation") are inhibited by the electric-potential barrier of the citrate-stabilized particles, while binding affinities increase linearly with the charges (from 5- to 9-) of structurally different POM anions, suggesting that no single orientation ("lattice matching") is required for monolayer self-assembly. Time-dependent cryo-TEM images reveal that monolayer growth occurs via "islands", a mechanism that points to cation-mediated attraction between bound POMs. Complete ligand shells comprised of 330 molecules of alpha-AlW(11)O(39)(9-) (1) possess small net charges (29e from zeta-potential measurements) and short Debye lengths (kappa(-1) = 1.0 nm), which indicate that approximately 99% of the 2970 K(+) counter cations lie within ca. 1.5 nm (approximately 3 hydrated K(+) ion diameters) from the outer surface of the POM shell. Energetic analysis of

  17. Direct imaging of electron recombination and transport on a semiconductor surface by femtosecond time-resolved photoemission electron microscopy

    SciTech Connect

    Fukumoto, Keiki Yamada, Yuki; Koshihara, Shin-ya; Onda, Ken

    2014-02-03

    Much effort has been devoted to the development of techniques to probe carrier dynamics, which govern many semiconductor device characteristics. We report direct imaging of electron dynamics on semiconductor surfaces by time-resolved photoemission electron microscopy using femtosecond laser pulses. The experiments utilized a variable-repetition-rate femtosecond laser system to suppress sample charging problems. The recombination of photogenerated electrons and the lateral motion of the electrons driven by an external electric field on a GaAs surface were visualized. The mobility was estimated from a linear relationship between the drift velocity and the potential gradient.

  18. In vivo nanomechanical imaging of blood-vessel tissues directly in living mammals using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Mao, Youdong; Sun, Quanmei; Wang, Xiufeng; Ouyang, Qi; Han, Li; Jiang, Lei; Han, Dong

    2009-07-01

    Atomic force microscopy (AFM) is difficult to achieve in living mammals but is necessary for understanding mechanical properties of tissues in their native form in organisms. Here we report in vivo nanomechanical imaging of blood-vessel tissues directly in living mammalians by AFM combined with surgical operations. Nanomechanical heterogeneity of blood vessels is observed across the diverse microenvironments of the same tissues in vivo. This method is further used to measure the counteractive nanomechanical changes in real time during drug-induced vasodilation and vasoconstriction in vivo, demonstrating appealing potential in characterization of in vivo nanomechanical dynamics of native tissues.

  19. Material Property Estimation for Direct Detection of DNAPL using Integrated Ground-Penetrating Radar Velocity, Imaging and Attribute Analysis

    SciTech Connect

    John H. Bradford; Stephen Holbrook; Scott B. Smithson

    2004-12-09

    The focus of this project is direct detection of DNAPL's specifically chlorinated solvents, via material property estimation from multi-fold surface ground-penetrating radar (GPR) data. We combine state-of-the-art GPR processing methodology with quantitative attribute analysis and material property estimation to determine the location and extent of residual and/or pooled DNAPL in both the vadose and saturated zones. An important byproduct of our research is state-of-the-art imaging which allows us to pinpoint attribute anomalies, characterize stratigraphy, identify fracture zones, and locate buried objects.

  20. Underwater imaging using a hybrid Kirchhoff migration: direction of arrival method and a sparse surface sensor array.

    PubMed

    Dord, Jean-Francois; Farhat, Charbel

    2010-08-01

    This paper considers the problem of imaging a complex object submerged in shallow waters using a sparse surface sensor array and a hybrid signal processing method. This method is constructed by refining the Kirchhoff migration technique to incorporate a zoning of the sensors and an analysis of multiple reflections, and combining it with the direction of arrival estimation method. Its performance is assessed and analyzed with the shape identification of a mockup submarine by numerical simulation. The obtained numerical results highlight the potential of this approach for identifying underwater intruders.

  1. Bayesian reconstruction of P(r) directly from two-dimensional detector images via a Markov chain Monte Carlo method

    PubMed Central

    Paul, Sudeshna; Friedman, Alan M.; Bailey-Kellogg, Chris; Craig, Bruce A.

    2013-01-01

    The interatomic distance distribution, P(r), is a valuable tool for evaluating the structure of a molecule in solution and represents the maximum structural information that can be derived from solution scattering data without further assumptions. Most current instrumentation for scattering experiments (typically CCD detectors) generates a finely pixelated two-dimensional image. In contin­uation of the standard practice with earlier one-dimensional detectors, these images are typically reduced to a one-dimensional profile of scattering inten­sities, I(q), by circular averaging of the two-dimensional image. Indirect Fourier transformation methods are then used to reconstruct P(r) from I(q). Substantial advantages in data analysis, however, could be achieved by directly estimating the P(r) curve from the two-dimensional images. This article describes a Bayesian framework, using a Markov chain Monte Carlo method, for estimating the parameters of the indirect transform, and thus P(r), directly from the two-dimensional images. Using simulated detector images, it is demonstrated that this method yields P(r) curves nearly identical to the reference P(r). Furthermore, an approach for evaluating spatially correlated errors (such as those that arise from a detector point spread function) is evaluated. Accounting for these errors further improves the precision of the P(r) estimation. Experimental scattering data, where no ground truth reference P(r) is available, are used to demonstrate that this method yields a scattering and detector model that more closely reflects the two-dimensional data, as judged by smaller residuals in cross-validation, than P(r) obtained by indirect transformation of a one-dimensional profile. Finally, the method allows concurrent estimation of the beam center and D max, the longest interatomic distance in P(r), as part of the Bayesian Markov chain Monte Carlo method, reducing experimental effort and providing a well defined protocol for these

  2. Bayesian reconstruction of P(r) directly from two-dimensional detector images via a Markov chain Monte Carlo method.

    PubMed

    Paul, Sudeshna; Friedman, Alan M; Bailey-Kellogg, Chris; Craig, Bruce A

    2013-04-01

    The interatomic distance distribution, P(r), is a valuable tool for evaluating the structure of a molecule in solution and represents the maximum structural information that can be derived from solution scattering data without further assumptions. Most current instrumentation for scattering experiments (typically CCD detectors) generates a finely pixelated two-dimensional image. In contin-uation of the standard practice with earlier one-dimensional detectors, these images are typically reduced to a one-dimensional profile of scattering inten-sities, I(q), by circular averaging of the two-dimensional image. Indirect Fourier transformation methods are then used to reconstruct P(r) from I(q). Substantial advantages in data analysis, however, could be achieved by directly estimating the P(r) curve from the two-dimensional images. This article describes a Bayesian framework, using a Markov chain Monte Carlo method, for estimating the parameters of the indirect transform, and thus P(r), directly from the two-dimensional images. Using simulated detector images, it is demonstrated that this method yields P(r) curves nearly identical to the reference P(r). Furthermore, an approach for evaluating spatially correlated errors (such as those that arise from a detector point spread function) is evaluated. Accounting for these errors further improves the precision of the P(r) estimation. Experimental scattering data, where no ground truth reference P(r) is available, are used to demonstrate that this method yields a scattering and detector model that more closely reflects the two-dimensional data, as judged by smaller residuals in cross-validation, than P(r) obtained by indirect transformation of a one-dimensional profile. Finally, the method allows concurrent estimation of the beam center and Dmax, the longest interatomic distance in P(r), as part of the Bayesian Markov chain Monte Carlo method, reducing experimental effort and providing a well defined protocol for these

  3. Maximizing the ExoEarth candidate yield from a future direct imaging mission

    SciTech Connect

    Stark, Christopher C.; Roberge, Aki; Mandell, Avi; Robinson, Tyler D.

    2014-11-10

    ExoEarth yield is a critical science metric for future exoplanet imaging missions. Here we estimate exoEarth candidate yield using single visit completeness for a variety of mission design and astrophysical parameters. We review the methods used in previous yield calculations and show that the method choice can significantly impact yield estimates as well as how the yield responds to mission parameters. We introduce a method, called Altruistic Yield Optimization, that optimizes the target list and exposure times to maximize mission yield, adapts maximally to changes in mission parameters, and increases exoEarth candidate yield by up to 100% compared to previous methods. We use Altruistic Yield Optimization to estimate exoEarth candidate yield for a large suite of mission and astrophysical parameters using single visit completeness. We find that exoEarth candidate yield is most sensitive to telescope diameter, followed by coronagraph inner working angle, followed by coronagraph contrast, and finally coronagraph contrast noise floor. We find a surprisingly weak dependence of exoEarth candidate yield on exozodi level. Additionally, we provide a quantitative approach to defining a yield goal for future exoEarth-imaging missions.

  4. Interferometric direct imaging properties of a BIGRE-DAM device in laboratory

    NASA Astrophysics Data System (ADS)

    Patru, Fabien; Antichi, Jacopo; Rabou, Patrick; Giro, Enrico; Farinato, Jacopo; Gratton, Raffaele; Vassallo, Daniele; Verinaud, Christophe; Mourard, Denis; Girard, Julien

    2016-08-01

    DAM (Discretized Aperture Mapping) is an original optical concept able to improve the performance in high angular resolution and high contrast imaging by the present class of large telescopes equipped with adaptive optics. By discretizing the entrance pupil of a large telescope into an array of many coherent sub-apertures, DAM provides unique imaging and filtering properties by means of spatial filtering and interferometric techniques. DAM can be achieved by means of single-mode fibers, integrated optic waveguides, pinholes, or simply with an innovative BIGRE optical device. BIGRE is formed of an afocal double micro-lenses array. In addition to the pupil discretization process by spatial filtering, BIGRE can also provide two other optical processes: the pupil densification or the pupil dilution. DAD (Discretized Aperture Densification) increase the sub-aperture sizes and is suitable to a hypertelescope, whereas DADI (Discretized Aperture Dilution Interferometry) reduces the sub-aperture sizes and turns a large telescope into a Fizeau interferometer. This paper deals with the first in-lab experiment at visible wavelength of BIGRE devices for the three configurations above. We study the point spread function (PSF) when observing a point-like object located either on-axis or at various off-axis positions across the field of view. Both interferometric and diffractive effects are described. The experimental measurements are in good agreement with the BIGRE theory. It results that BIGRE fulfils the requirements to carry out spatially filtered pupil discretization (DAM), with possible densification (DAD) or dilution (DADI).

  5. Direct Imaging Discovery of a Remarkably Red Planetary-Mass Companion

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.; Liu, Michael C.; Mawet, Dimitri; Ngo, Henry; Malo, Lison; Mace, Gregory N.; McLane, Jacob; Lu, Jessica; Tristan, Isaiah; Hinkley, Sasha; Hillenbrand, Lynne; Shkolnik, Evgenya L.; Benneke, Björn; Best, William M. J.

    2017-01-01

    High-contrast imaging surveys have uncovered a growing number of planets orbiting young stars, but the evolution of giant planet atmospheres from dusty L dwarfs to cloud-free T dwarfs remains poorly constrained. We present the discovery of an 11-14 Mjup late-L dwarf companion to a likely member of the ~120 Myr AB Dor moving group as part of a large adaptive optics imaging program to find and characterize planets at Keck Observatory. The near-infrared colors of this new object are redder than the young giant planets HR 8799 bcde and nearly all free-floating red L dwarfs currently known. In color-magnitude diagrams, this object is located at the tip of the red L dwarf sequence and marks the ``elbow'' of the AB Dor substellar isochrone, implying that giant planets can retain thick clouds even at relatively old ages (>100 Myr). Altogether, this new benchmark offers important clues about the evolutionary timescales and physical properties of clouds in giant planet atmospheres.

  6. Segmentation of vessels in retinal images based on directional height statistics.

    PubMed

    Lazar, Istvan; Hajdu, Andras

    2012-01-01

    In this paper we present a fast and simple, yet accurate method for the segmentation of retinal blood vessels. Many diseases of the eye result in the distortions of the vessels. The precise location of the major optic veins may be used for the localization of other anatomical parts, such as the macula and the optic disc. Also, many microaneurysm detection methods consider an additional vessel segmentation step. The proposed method realizes the recognition of vessels through considering cross-sections of the image at different orientations. Peaks on the profiles are localized and their heights are measured. This way, a set of height values are assigned to every pixel of the image. Simple statistics are calculated for every pixel, and combined to construct a vessel score map. We apply a simple thresholding procedure and postprocessing step to obtain a binary vessel mask. The method has been tested on the publicly available DRIVE database, and it proved to be competitive with the state-of-the-art.

  7. An application of particle image velocimetry to the direct measurement of laminar burning velocity in homogeneous propane-air mixtures

    SciTech Connect

    Zhou, M.; Garner, C.P.

    1995-12-31

    An experiment is described for the direct measurement of laminar burning velocity within an optically accessed cylindrical combustion chamber. The laminar burning velocity was determined directly as the difference between the flame propagation speed and the unburned gas velocity immediately ahead of the flame front. Particle Image Velocimetry (PIV) has been applied to measure the unburned gas velocity field. The local flame speed and flame front position were determined from a pair of ionization probes in conjunction with the simultaneous PIV measurement. The laminar burning velocity of propane-air mixtures initially at atmospheric condition for different equivalence ratios ranging from 0.7--1.4 are presented. Close agreement with other measurements and predicted results was found.

  8. Pore sub-features reproducibility in direct microscopic and Livescan images--their reliability in personal identification.

    PubMed

    Gupta, Abhishek; Sutton, Raul

    2010-07-01

    Third level features have been reported to have equal discriminatory power as second level details in establishing personal identification. Pore area, as an extended set third level sub-feature, has been studied by minimizing possible factors that could affect pore size. The reproducibility of pore surface area has been studied using direct microscopic and 500 ppi Livescan images. Direct microscopic pore area measurements indicated that the day on which the pore area was measured had a significant impact on the measured pore area. Pore area measurement was shown to be difficult to estimate in 500 ppi Livescan measurements owing to lack of resolution. It is not possible to reliably use pore area as an identifying feature in fingerprint examination.

  9. Inverse synthetic aperture radar imaging compensation method based on coherent processing of intermediate frequency direct sampling data

    NASA Astrophysics Data System (ADS)

    Zou, Jiangwei; Tian, Biao; Chen, Zengping

    2016-07-01

    An inverse synthetic aperture radar (ISAR) high-precision compensation method is proposed based on coherent processing of intermediate frequency direct sampling data. First, the compensation of high-speed movement is performed by a modified linear frequency modulation matched filter during the pulse compression. The motion trajectory in the down-range direction is then reconstructed by compensation of window sampling difference of each pulse. Modified envelope correlation is applied to calculate the range profile shift between each pulse and the first one. Polynomial fitting is adopted to accurately estimate the motion characteristics. Subsequently, coherent processing is applied by combining range alignment and initial phase compensation. The migration through range cells correction can be then realized by keystone transform to the highly coherent data. Consequently, ISAR images with high quality are achieved. Experimental results on simulated and real data have demonstrated the validity of the proposed method.

  10. Directional, horizontal inhomogeneities of cloud optical thickness fields retrieved from ground-based and airbornespectral imaging

    NASA Astrophysics Data System (ADS)

    Schäfer, Michael; Bierwirth, Eike; Ehrlich, André; Jäkel, Evelyn; Werner, Frank; Wendisch, Manfred

    2017-02-01

    Clouds exhibit distinct horizontal inhomogeneities of their optical and microphysical properties, which complicate their realistic representation in weather and climate models. In order to investigate the horizontal structure of cloud inhomogeneities, 2-D horizontal fields of optical thickness (τ) of subtropical cirrus and Arctic stratus are investigated with a spatial resolution of less than 10 m. The 2-D τ-fields are derived from (a) downward (transmitted) solar spectral radiance measurements from the ground beneath four subtropical cirrus and (b) upward (reflected) radiances measured from aircraft above 10 Arctic stratus. The data were collected during two field campaigns: (a) Clouds, Aerosol, Radiation, and tuRbulence in the trade wind regime over BArbados (CARRIBA) and (b) VERtical Distribution of Ice in Arctic clouds (VERDI). One-dimensional and 2-D autocorrelation functions, as well as power spectral densities, are derived from the retrieved τ-fields. The typical spatial scale of cloud inhomogeneities is quantified for each cloud case. Similarly, the scales at which 3-D radiative effects influence the radiance field are identified. In most of the investigated cloud cases considerable cloud inhomogeneities with a prevailing directional structure are found. In these cases, the cloud inhomogeneities favour a specific horizontal direction, while across this direction the cloud is of homogeneous character. The investigations reveal that it is not sufficient to quantify horizontal cloud inhomogeneities using 1-D inhomogeneity parameters; 2-D parameters are necessary.

  11. Direct imaging search for planets around low-mass stars and spectroscopic characterization of young exoplanets

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan Peter

    Low--mass stars between 0.1--0.6 M⊙ are the most abundant members our galaxy and may be the most common sites of planet formation, but little is known about the outer architecture of their planetary systems. We have carried out a high-contrast adaptive imaging search for gas giant planets between 1--13 MJup around 122 newly identified young M dwarfs in the solar neighborhood ( ≲ 35 pc). Half of our targets are younger than 145 Myr, and 90% are younger than 580 Myr. After removing 39 resolved stellar binaries, our homogeneous sample of 83 single young M dwarfs makes it the largest imaging search for planets around low--mass stars to date. Our H- and K- band coronagraphic observations with Subaru/HiCIAO and Keck/NIRC2 achieve typical contrasts of 9--13 mag and 12--14 mag at 100, respectively, which corresponds to limiting masses of ˜1--10 M Jup at 10--30 AU for most of our sample. We discovered four brown dwarfs with masses between 25--60 MJup at projected separations of 4--190 AU. Over 100 candidate planets were discovered, nearly all of which were found to be background stars from follow-up second epoch imaging. Our null detection of planets nevertheless provides strong statistical constraints on the occurrence rate of giant planets around M dwarfs. Assuming circular orbits and a logarithmically-flat power law distribution in planet mass and semi--major axis of the form d 2N=(dloga dlogm) infinity m0 a0, we measure an upper limit (at the 95% confidence level) of 8.8% and 12.6% for 1--13 MJup companions between 10--100 AU for hot start and cold start evolutionary models, respectively. For massive gas giant planets in the 5--13 M Jup range like those orbiting HR 8799, GJ 504, and beta Pictoris, we find that fewer than 5.3% (7.8%) of M dwarfs harbor these planets between 10--100 AU for a hot start (cold start) formation scenario. Our best constraints are for brown dwarf companions; the frequency of 13--75 MJup companions between (de--projected) physical

  12. Direct high-resolution label-free imaging of cellular nanostructure dynamics in living cells

    NASA Astrophysics Data System (ADS)

    Heo, Chaejeong; Lee, Sohee; Lee, Si Young; Jeong, Mun Seok; Lee, Young Hee; Suh, Minah

    2013-06-01

    We report the application of an optical microscope equipped with a high-resolution dark-field condenser for detecting dynamic responses of cellular nanostructures in real time. Our system provides an easy-to-use technique to visualize biological specimens without any staining. This system can visualize the dynamic behavior of nanospheres and nanofibers, such as F-actin, at the leading edges of adjacent neuronal cells. We confirmed that the nanofibers imaged with this high-resolution optical microscopic technique are F-actin by using fluorescence microscopy after immunostaining the F-actin of fixed cells. Furthermore, cellular dynamics are enhanced by applying noncontact electric field stimulation through a transparent graphene electric field stimulator. High-resolution label-free optical microscopy enables the visualization of nanofiber dynamics initiated by filopodial nanofiber contacts. In conclusion, our optical microscopy system allows the visualization of nanoscale cellular dynamics under various external stimuli in real time without specific staining.

  13. Direct visualization of carbon nanotube degradation in primary cells by photothermal imaging.

    PubMed

    Russier, Julie; Oudjedi, Laura; Piponnier, Martin; Bussy, Cyrill; Prato, Maurizio; Kostarelos, Kostas; Lounis, Brahim; Bianco, Alberto; Cognet, Laurent

    2017-04-06

    Assessment of biodegradability of carbon nanotubes (CNTs) is a critically important aspect that needs to be solved before their translation into new biomedical tools. CNT biodegradation has been shown both in vitro and in vivo, but we are limited by the number of analytical techniques that can be used to follow the entire process. Photothermal imaging (PhI) is an innovative technique that enables the quantitative detection of nanometer-sized absorptive objects. In this study, we demonstrate that PhI allows the observation of the degradation process of functionalized multi-walled carbon nanotubes (MWCNTs) following their internalization by primary glial cells. The absence of interference from the biological matrix components, together with the possibility to combine PhI with other detection techniques (e.g. fluorescence, light or electron microscopy) validate the potential of this method to follow the fate and behavior of carbon nanostructures in a biological environment.

  14. Direct holographic imaging of ultrafast laser damage process in thin films.

    PubMed

    Siaulys, Nerijus; Gallais, Laurent; Melninkaitis, Andrius

    2014-04-01

    Dynamic process of femtosecond laser-induced damage formation in dielectric thin films is reconstructed from a series of time-resolved images. Ta2O5 single-layer coatings of four different thicknesses have been investigated in transmission mode by means of time-resolved off-axis digital holography. Different processes overlapped in time were found to occur; namely, the Kerr effect, free-electron generation, ultrafast lattice heating, and shockwave generation. The trends in contribution of these effects are qualitatively reproduced by numerical models based on electron-rate equations and Drude theory, which take into account transient changes in the films and interference effects of the pump and probe pulses.

  15. Proximal surface caries detection with direct-exposure and rare earth screen/film imaging

    SciTech Connect

    Lundeen, R.C.; McDavid, W.D.; Barnwell, G.M.

    1988-12-01

    This laboratory study compared five imaging systems for their diagnostic accuracy in detection of proximal surface dental caries. Ten viewers provided data on radiographic detectability of carious lesions. The diagnostic accuracy of each system was determined with receiver operating characteristic (ROC) curves by comparing viewer data with the true state of the teeth as determined microscopically. D-speed film marginally outperformed the other four systems, but the three screen/film systems matched the diagnostic accuracy of E-speed film. Radiation reductions between 62% and 92% were achieved with the screen/film systems when compared to the two conventional dental films. The feasibility of designing a screen/film bite-wing cassette was shown, but the poor diagnostic accuracy of the present bite-wing system indicated a need for a new technology in caries detection.

  16. Direct imaging of monovacancy-hydrogen complexes in a single graphitic layer

    NASA Astrophysics Data System (ADS)

    Ziatdinov, Maxim; Fujii, Shintaro; Kusakabe, Koichi; Kiguchi, Manabu; Mori, Takehiko; Enoki, Toshiaki

    2014-04-01

    Understanding how foreign chemical species bond to atomic vacancies in graphene layers can advance our ability to tailor the electronic and magnetic properties of defective graphenic materials. Here, we use ultrahigh-vacuum scanning tunneling microscopy (UHV-STM) and density functional theory to identify the precise structure of hydrogenated single atomic vacancies in a topmost graphene layer of graphite and establish a connection between the details of hydrogen passivation and the electronic properties of a single atomic vacancy. Monovacancy-hydrogen complexes are prepared by sputtering of the graphite surface layer with low-energy ions and then exposing it briefly to an atomic hydrogen environment. High-resolution experimental UHV-STM imaging allows us to determine unambiguously the positions of single missing atoms in the defective graphene lattice and, in combination with the ab initio calculations, provides detailed information about the distribution of low-energy electronic states on the periphery of the monovacancy-hydrogen complexes. We found that a single atomic vacancy where each σ dangling bond is passivated with one hydrogen atom shows a well-defined signal from the nonbonding π state, which penetrates into the bulk with a √3 ×√3 R30∘ periodicity. However, a single atomic vacancy with full hydrogen termination of σ dangling bonds and additional hydrogen passivation of the extended π state at one of the vacancy's monohydrogenated carbon atoms is characterized by complete quenching of low-energy localized states. In addition, we discuss the migration of hydrogen atoms at the periphery of the monovacancy-hydrogen complexes, which dramatically change the vacancy's low-energy electronic properties, as observed in our low-bias, high-resolution STM imaging.

  17. GEM-based TPC with CCD imaging for directional dark matter detection

    NASA Astrophysics Data System (ADS)

    Phan, N. S.; Lauer, R. J.; Lee, E. R.; Loomba, D.; Matthews, J. A. J.; Miller, E. H.

    2016-11-01

    The most mature directional dark matter experiments at present all utilize low-pressure gas Time Projection Chamber (TPC) technologies. We discuss some of the challenges for this technology, for which balancing the goal of achieving the best sensitivity with that of cost effective scale-up requires optimization over a large parameter space. Critical for this are the precision measurements of the fundamental properties of both electron and nuclear recoil tracks down to the lowest detectable energies. Such measurements are necessary to provide a benchmark for background discrimination and directional sensitivity that could be used for future optimization studies for directional dark matter experiments. In this paper we describe a small, high resolution, high signal-to-noise GEM-based TPC with a 2D CCD readout designed for this goal. The performance of the detector was characterized using alpha particles, X-rays, gamma-rays, and neutrons, enabling detailed measurements of electron and nuclear recoil tracks. Stable effective gas gains of greater than 1 × 105 were obtained in 100 Torr of pure CF4 by a cascade of three standard CERN GEMs each with a 140 μm pitch. The high signal-to-noise and sub-millimeter spatial resolution of the GEM amplification and CCD readout, together with low diffusion, allow for excellent background discrimination between electron and nuclear recoils down below ∼10 keVee (∼23 keVr fluorine recoil). Even lower thresholds, necessary for the detection of low mass WIMPs for example, might be achieved by lowering the pressure and utilizing full 3D track reconstruction. These and other paths for improvements are discussed, as are possible fundamental limitations imposed by the physics of energy loss.

  18. Interactive Digital Image Processing for Terrain Data Extraction, Phase 4.

    DTIC Science & Technology

    1983-11-01

    the images appear to be displaced radial1l toward the isocenter on the upper side of the photograph and radially outward or away from the isocenter ...on the lower side. Along the isometric parallel (line through the isocenter perpendicular to the direction of tilt) there is no displacement relative...the principal point P (geometric center. This is equal to the Focal lengtr of the camera. t = Tilt angle i = Isocenter n = Nadir Di = Distance of image

  19. Direct radiolabeling of antibody against stage specific embryonic antigen for diagnostic imaging

    DOEpatents

    Rhodes, B.A.

    1994-09-13

    Antibodies against stage specific embryonic antigen-1 is radiolabeled by direct means with a radionuclide for use in detection of occult abscess and inflammation. Radiolabeling is accomplished by partial reduction of the disulfide bonds of the antibody using Sn(II), or using other reducing agents followed by the addition of Sn(II), removal of excess reducing agent and reduction by-products, and addition of a specified amount of radionuclide reducing agent, such as stannous tartrate. The resulting product may be stored frozen or lyophilized, with radiolabeling accomplished by the addition of the radionuclide. No Drawings

  20. Direct radiolabeling of antibody against stage specific embryonic antigen for diagnostic imaging

    DOEpatents

    Rhodes, Buck A.

    1994-01-01

    Antibody against stage specific embryonic antigen-1 is radiolabeled by direct means with a radionuclide for use in detection of occult abscess and inflammation. Radiolabeling is accomplished by partial reduction of the disulfide bonds of the antibody using Sn(II), or using other reducing agents followed by the addition of Sn(II), removal of excess reducing agent and reduction by-products, and addition of a specified amount of radionuclide reducing agent, such as stannous tartrate. The resulting product may be store frozen or lyophilized, with radiolabeling accomplished by the addition of the radionuclide.

  1. Novel mass spectrometry imaging software assisting labeled normalization and quantitation of drugs and neuropeptides directly in tissue sections.

    PubMed

    Källback, Patrik; Shariatgorji, Mohammadreza; Nilsson, Anna; Andrén, Per E

    2012-08-30

    MALDI MS imaging has been extensively used to produce qualitative distribution maps of proteins, peptides, lipids, small molecule pharmaceuticals and their metabolites directly in biological tissue sections. There is growing demand to quantify the amount of target compounds in the tissue sections of different organs. We present a novel MS imaging software including protocol for the quantitation of drugs, and for the first time, an endogenous neuropeptide directly in tissue sections. After selecting regions of interest on the tissue section, data is read and processed by the software using several available methods for baseline corrections, subtractions, denoising, smoothing, recalibration and normalization. The concentrations of in vivo administered drugs or endogenous compounds are then determined semi-automatically using either external standard curves, or by using labeled compounds, i.e., isotope labeled analogs as standards. As model systems, we have quantified the distribution of imipramine and tiotropium in the brain and lung of dosed rats. Substance P was quantified in different mouse brain structures, which correlated well with previously reported peptide levels. Our approach facilitates quantitative data processing and labeled standards provide better reproducibility and may be considered as an efficient tool to quantify drugs and endogenous compounds in tissue regions of interest.

  2. ON THE MISALIGNMENT OF THE DIRECTLY IMAGED PLANET {beta} PICTORIS b WITH THE SYSTEM'S WARPED INNER DISK

    SciTech Connect

    Dawson, Rebekah I.; Murray-Clay, Ruth A.; Fabrycky, Daniel C.

    2011-12-10

    The vertical warp in the debris disk {beta} Pictoris-an inclined inner disk extending into a flat outer disk-has long been interpreted as the signpost of a planet on an inclined orbit. Direct images spanning 2004-2010 have revealed {beta} Pictoris b, a planet with a mass and orbital distance consistent with this picture. However, it was recently reported that the orbit of planet b is aligned with the flat outer disk, not the inclined inner disk, and thus lacks the inclination to warp the disk. We explore three scenarios for reconciling the apparent misalignment of the directly imaged planet {beta} Pictoris b with the warped inner disk of {beta} Pictoris: observational uncertainty, an additional planet, and damping of planet b's inclination. We find that, at the extremes of the uncertainties, the orbit of {beta} Pictoris b has the inclination necessary to produce the observed warp. We also find that if planet b were aligned with the flat outer disk, it would prevent another planet from creating a warp with the observed properties; therefore planet b itself must be responsible for the warp. Finally, planet b's inclination could have been damped by dynamical friction and still produce the observed disk morphology, but the feasibility of damping depends on disk properties and the presence of other planets. More precise observations of the orbit of planet b and the position angle of the outer disk will allow us to distinguish between the first and third scenarios.

  3. Comparative Tumor Imaging and PDT Efficacy of HPPH Conjugated in the Mono- and Di-Forms to Various Polymethine Cyanine Dyes: Part - 2

    PubMed Central

    James, Nadine S.; Ohulchanskyy, Tymish Y.; Chen, Yihui; Joshi, Penny; Zheng, Xiang; Goswami, Lalit N.; Pandey, Ravindra K.

    2013-01-01

    Previous reports from our laboratory have shown that a bifunctional agent obtained by conjugating a photosensitizer (HPPH) to a cyanine dye (CD) can be used for fluorescence image-guided treatment of tumor by photodynamic therapy (PDT). However, the resulting HPPH-CD conjugate showed a significant difference between the tumor-imaging and therapeutic doses. It was demonstrated that the singlet oxygen (1O2*, a key cytotoxic agent in PDT) produced by the conjugate upon excitation of the HPPH moiety was partially quenched by the CD-moiety; this resulted in a reduced PDT response when compared to HPPH-PDT under similar treatment parameters. To improve the therapeutic potential of the conjugate, we synthesized a series of dual functional agents in which one or two HPPH moieties were separately conjugated to three different dyes (Cypate, modified IR820 or modified IR783). The newly synthesized conjugates were compared with our lead compound HPPH-CD in terms of photophysical properties, in vitro and in vivo PDT efficacy, tumor uptake and imaging potential. Among the analogs investigated, the conjugate, in which two HPPH moieties were linked to the modified IR820 produced enhanced tumor uptake and tumor contrast in both Colon 26 (a murine Colon carcinoma) and U87 (a human glioblastoma) cell lines. The long-term PDT efficacy (cure) of this conjugate in BALB/c mice, bearing Colon 26 tumors was also enhanced; however, its efficacy in Nude mice bearing U87 tumors was slightly reduced. It was also found that in all the conjugates the singlet oxygen generation and, consequently, PDT efficacy were compromised by a competing pathway, whereby an electronic excitation of HPPH, the energy donor, is deactivated through an electronic excitation energy transfer (Forster Resonance Energy Transfer, FRET) to the CD fluorophore, the energy acceptor, resulting in overall reduction of the singlet oxygen production. Conjugates with increased FRET showed reduced singlet oxygen production and PDT

  4. Embolization of an Internal Iliac Artery Aneurysm after Image-Guided Direct Puncture

    SciTech Connect

    Heye, S. Vaninbroukx, J.; Daenens, K.; Houthoofd, S.; Maleux, G.

    2012-08-15

    Objective: To evaluate the feasibility, safety, and efficacy of embolization of internal iliac artery aneurysm (IIAA) after percutaneous direct puncture under (cone-beam) computed tomography (CT) guidance. Methods: A retrospective case series of three patients, in whom IIAA not accessible by way of the transarterial route, was reviewed. CT-guided puncture of the IIAA sac was performed in one patient. Two patients underwent puncture of the IIAA under cone-beam CT guidance. Results: Access to the IIAA sac was successful in all three patients. In two of the three patients, the posterior and/or anterior division was first embolized using platinum microcoils. The aneurysm sac was embolized with thrombin in one patient and with a mixture of glue and Lipiodol in two patients. No complications were seen. On follow-up CT, no opacification of the aneurysm sac was seen. The volume of one IIAA remained stable at follow-up, and the remaining two IIAAs decreased in size. Conclusion: Embolization of IIAA after direct percutaneous puncture under cone-beam CT/CT-guidance is feasible and safe and results in good short-term outcome.

  5. Direct Depth- and Lateral- Imaging of Nanoscale Magnets Generated by Ion Impact

    PubMed Central

    Röder, Falk; Hlawacek, Gregor; Wintz, Sebastian; Hübner, René; Bischoff, Lothar; Lichte, Hannes; Potzger, Kay; Lindner, Jürgen; Fassbender, Jürgen; Bali, Rantej

    2015-01-01

    Nanomagnets form the building blocks for a variety of spin-transport, spin-wave and data storage devices. In this work we generated nanoscale magnets by exploiting the phenomenon of disorder-induced ferromagnetism; disorder was induced locally on a chemically ordered, initially non-ferromagnetic, Fe60Al40 precursor film using  nm diameter beam of Ne+ ions at 25 keV energy. The beam of energetic ions randomized the atomic arrangement locally, leading to the formation of ferromagnetism in the ion-affected regime. The interaction of a penetrating ion with host atoms is known to be spatially inhomogeneous, raising questions on the magnetic homogeneity of nanostructures caused by ion-induced collision cascades. Direct holographic observations of the flux-lines emergent from the disorder-induced magnetic nanostructures were made in order to measure the depth- and lateral- magnetization variation at ferromagnetic/non-ferromagnetic interfaces. Our results suggest that high-resolution nanomagnets of practically any desired 2-dimensional geometry can be directly written onto selected alloy thin films using a nano-focussed ion-beam stylus, thus enabling the rapid prototyping and testing of novel magnetization configurations for their magneto-coupling and spin-wave properties. PMID:26584789

  6. Basalt-flow imaging using a high-resolution directional borehole radar

    USGS Publications Warehouse

    Moulton, C.W.; Wright, D.L.; Hutton, S.R.; Smith, D.V.G.; Abraham, J.D.

    2002-01-01

    A new high-resolution directional borehole radar-logging tool (DBOR tool) was used to log three wells at the Idaho National Engineering and Environmental Laboratory (INEEL). The radar system uses identical directional cavity-backed monopole transmitting and receiving antennas that can be mechanically rotated while the tool is stationary or moving slowly in a borehole. Faster reconnaissance logging with no antenna rotation was also done to find zones of interest. The microprocessor-controlled motor/encoder in the tool can rotate the antennas azimuthally, to a commanded angle, accurate to a within few degrees. The three logged wells in the unsaturated zone at the INEEL had been cored with good core recovery through most zones. After coring, PVC casing was installed in the wells. The unsaturated zone consists of layered basalt flows that are interbedded with thin layers of coarse-to-fine grained sediments. Several zones were found that show distinctive signatures consistent with fractures in the basalt. These zones may correspond to suspected preferential flow paths. The DBOR data were compared to core, and other borehole log information to help provide better understanding of hydraulic flow and transport in preferential flow paths in the unsaturated zone basalts at the INEEL.

  7. High-speed fuel tracer fluorescence and OH radical chemiluminescence imaging in a spark-ignition direct-injection engine.