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Sample records for accurate spatially resolved

  1. Hyperspectral imaging-based spatially-resolved technique for accurate measurement of the optical properties of horticultural products

    NASA Astrophysics Data System (ADS)

    Cen, Haiyan

    Hyperspectral imaging-based spatially-resolved technique is promising for determining the optical properties and quality attributes of horticultural and food products. However, considerable challenges still exist for accurate determination of spectral absorption and scattering properties from intact horticultural products. The objective of this research was, therefore, to develop and optimize hyperspectral imaging-based spatially-resolved technique for accurate measurement of the optical properties of horticultural products. Monte Carlo simulations and experiments for model samples of known optical properties were performed to optimize the inverse algorithm of a single-layer diffusion model and the optical designs, for extracting the absorption (micro a) and reduced scattering (micros') coefficients from spatially-resolved reflectance profiles. The logarithm and integral data transformation and the relative weighting methods were found to greatly improve the parameter estimation accuracy with the relative errors of 10.4%, 10.7%, and 11.4% for micro a, and 6.6%, 7.0%, and 7.1% for micros', respectively. More accurate measurements of optical properties were obtained when the light beam was of Gaussian type with the diameter of less than 1 mm, and the minimum and maximum source-detector distances were 1.5 mm and 10--20 transport mean free paths, respectively. An optical property measuring prototype was built, based on the optimization results, and evaluated for automatic measurement of absorption and reduced scattering coefficients for the wavelengths of 500--1,000 nm. The instrument was used to measure the optical properties, and assess quality/maturity, of 500 'Redstar' peaches and 1039 'Golden Delicious' (GD) and 1040 'Delicious' (RD) apples. A separate study was also conducted on confocal laser scanning and scanning electron microscopic image analysis and compression test of fruit tissue specimens to measure the structural and mechanical properties of 'Golden

  2. Practical aspects of spatially high accurate methods

    NASA Technical Reports Server (NTRS)

    Godfrey, Andrew G.; Mitchell, Curtis R.; Walters, Robert W.

    1992-01-01

    The computational qualities of high order spatially accurate methods for the finite volume solution of the Euler equations are presented. Two dimensional essentially non-oscillatory (ENO), k-exact, and 'dimension by dimension' ENO reconstruction operators are discussed and compared in terms of reconstruction and solution accuracy, computational cost and oscillatory behavior in supersonic flows with shocks. Inherent steady state convergence difficulties are demonstrated for adaptive stencil algorithms. An exact solution to the heat equation is used to determine reconstruction error, and the computational intensity is reflected in operation counts. Standard MUSCL differencing is included for comparison. Numerical experiments presented include the Ringleb flow for numerical accuracy and a shock reflection problem. A vortex-shock interaction demonstrates the ability of the ENO scheme to excel in simulating unsteady high-frequency flow physics.

  3. Spatially Resolved Infrared Spectroscopy of Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Knop, Robert Andrew, Jr.

    This thesis presents infrared spectroscopy of the circumnuclear regions of 23 Seyfert galaxies. Observations are spectrally resolved with a resolution of λΔλ~1000 and spatially resolved to ~1'', corresponding to ~102 pc for the objects in the sample. The instrument used for the observations, the Palomar Near-Infrared Spectrometer, is described, and problems peculiar to reduction of data from it are discussed. The lines observed include Paβ, Brγ, (FeII) (λ=1.2567μm), and H2 (λ=2.1213μm). In nine objects, the coronal line (SIX) (λ=1.2524μm) is also detected. Spatially resolved line emission is clearly visible in approximately half of the objects observed. The data for five of the objects showing the best spatially resolved infrared line emission are analyzed in detail. These objects include Seyfert 1.5 galaxy NGC 4151 and Seyfert 2 galaxies Mk 1066, NGC 2110, NGC 4388, and Mk 3. The data for the remaining objects is presented in tabular form, and each object is discussed briefly. The data argue that processes associated with the Seyfert nucleus are responsible for the bulk of the observed (FeII) emission. Kinematic and spatial associations can be drawn between features in the (FeII) line profiles and other processes associated with the active nucleus, such as outflows seen in ionized optical emission and radio lobes. Most of the (FeII) appears to emerge from partially ionized regions excited by nuclear x-rays, with an additional contribution from fast shocks. Some of the H2 emission also appears to be associated with the nuclear activity. However, in some cases the H2 emission is observed to have a different spatial distribution from (FeII) and the H+ emission. The H2 emission is probably thermally excited. No significant differences are found between the infrared line emission of Seyfert and Seyfert 1.x galaxies.

  4. Spatially resolved spectral-imaging device

    DOEpatents

    Bloom, Joshua Simon; Tyson, John Anthony

    2016-02-09

    A spatially resolved spectral device comprising a dispersive array to receive an incident light comprising a principal ray. The dispersive array comprising a plurality of dichroic layers, each of the plurality of dichroic layers disposed in a path of a direction of the principal ray. Each of the plurality of dichroic layers configured to at least one of reflect or transmit a different wavelength range of the incident light. The device further comprising a detection array operatively coupled with the dispersive array. The detection array comprising a photosensitive component including a plurality of detection pixels, each of the plurality of detection pixels having a light-receiving surface disposed parallel to the direction of the principal ray to detect a respective one of the different wavelength ranges of incident light reflected from a corresponding one of the plurality of dichroic layers.

  5. Resolving coastal conflicts using marine spatial planning.

    PubMed

    Tuda, Arthur O; Stevens, Tim F; Rodwell, Lynda D

    2014-01-15

    We applied marine spatial planning (MSP) to manage conflicts in a multi-use coastal area of Kenya. MSP involves several steps which were supported by using geographical information systems (GISs), multi-criteria decision analysis (MCDA) and optimization. GIS was used in identifying overlapping coastal uses and mapping conflict hotspots. MCDA was used to incorporate the preferences of user groups and managers into a formal decision analysis procedure. Optimization was applied in generating optimal allocation alternatives to competing uses. Through this analysis three important objectives that build a foundation for future planning of Kenya's coastal waters were achieved: 1) engaging competing stakeholders; 2) illustrating how MSP can be adapted to aid decision-making in multi-use coastal regions; and 3) developing a draft coastal use allocation plan. The successful application of MSP to resolve conflicts in coastal regions depends on the level of stakeholder involvement, data availability and the existing knowledge base. PMID:24361729

  6. Spatially resolved photoluminescence spectroscopy of quantum dots

    NASA Astrophysics Data System (ADS)

    Dybiec, Maciej

    applications was in the scope of this research. Bio-conjugation and functionalization are the fundamental issues for bio-marker tagging application of semiconductor quantum dots. It was discovered that spatially resolved photoluminescence spectroscopy and PL photo-degradation kinetics can confirm the bio-conjugation. Development of a methodology that will allow the spectroscopic confirmation of bio-conjugation of quantum dot fluorescent tags and optimization of their performance was the final goal for this research project.

  7. Passive background correction method for spatially resolved detection

    DOEpatents

    Schmitt, Randal L.; Hargis, Jr., Philip J.

    2011-05-10

    A method for passive background correction during spatially or angularly resolved detection of emission that is based on the simultaneous acquisition of both the passive background spectrum and the spectrum of the target of interest.

  8. Resolving Ambiguity from Competing Spatial Frames of Reference.

    ERIC Educational Resources Information Center

    Codd, Judith; Bialystok, Ellen

    A 2-part investigation was conducted to examine the ways children resolve the inherent ambiguity of spatial descriptions in terms of cues indicated by the three constituents of spatial propositions: predicate, referent, and relatum. In the first study, it was hypothesized that certain objects, structural markers, and definite articles accompanying…

  9. Spatially resolved winds on an exoplanet

    NASA Astrophysics Data System (ADS)

    Louden, Tom Michael; Wheatley, Peter

    2015-12-01

    We will present evidence that the atmosphere of the hot Jupiter HD 189733b has a strong eastward motion, with red-shifted absorption detected on the leading limb of the planet and blue-shifted absorption on the trailing limb. Our results are based on a time-resolved model of the sodium transmission spectrum measured with the HARPS spectrograph. The model includes limb darkening and stellar rotation, and it accounts implicitly for the Rossiter-McLaughlin effect.Our results can be understood as a combination of tidally locked planetary rotation and an eastward equatorial jet. The equatorial jet has long been predicted in atmospheric circulation models, and it helps to explain Spitzer maps of the dayside thermal emission of HD 189733b that show the hottest point of the planetary atmosphere offset to the east of the substellar point. In addition to testing atmospheric circulation models, our results demonstrate the feasibility of studying weather systems on distant planets.

  10. Spatially resolving antenna arrays using frequency diversity.

    PubMed

    Marks, Daniel L; Gollub, Jonah; Smith, David R

    2016-05-01

    Radio imaging devices and synthetic aperture radar typically use either mechanical scanning or phased arrays to illuminate a target with spatially varying radiation patterns. Mechanical scanning is unsuitable for many high-speed imaging applications, and phased arrays contain many active components and are technologically and cost prohibitive at millimeter and terahertz frequencies. We show that antennas deliberately designed to produce many different radiation patterns as the frequency is varied can reduce the number of active components necessary while still capturing high-quality images. This approach, called frequency-diversity imaging, can capture an entire two-dimensional image using only a single transmit and receive antenna with broadband illumination. We provide simple principles that ascertain whether a design is likely to achieve particular resolution specifications, and illustrate these principles with simulations. PMID:27140887

  11. Response Surface Methods For Spatially-Resolved Optical Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatially-resolved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/- 30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-lightweight, inflatable space antenna at NASA Langley Research Center. Photogrammetry is used to simultaneously measure the shape of the antenna at approximately 500 discrete spatial locations. RSM allows an analytic model to be developed that describes the shape of the majority of the antenna with an uncertainty of 0.4 mm, with 95% confidence. This model would allow a quantitative comparison between the actual shape of the antenna and the original design shape. Accurately determining this shape also allows confident interpolation between the measured points. Such a model could, for example, be used for ray tracing of radio-frequency waves up to 95 GHz. to predict the performance of the antenna.

  12. The spatial resolving power of earth resources satellites: A review

    NASA Technical Reports Server (NTRS)

    Townshend, J. R. G.

    1980-01-01

    The significance of spatial resolving power on the utility of current and future Earth resources satellites is critically discussed and the relative merits of different approaches in defining and estimating spatial resolution are outlined. It is shown that choice of a particular measure of spatial resolution depends strongly on the particular needs of the user. Several experiments have simulated the capabilities of future satellite systems by degradation of aircraft images. Surprisingly, many of these indicated that improvements in resolution may lead to a reduction in the classification accuracy of land cover types using computer assisted methods. However, where the frequency of boundary pixels is high, the converse relationship is found. Use of imagery dependent upon visual interpretation is likely to benefit more consistently from higher resolutions. Extraction of information from images will depend upon several other factors apart from spatial resolving power: these include characteristics of the terrain being sensed, the image processing methods that are applied as well as certain sensor characteristics.

  13. Spatially resolved scatter measurement of diffractive micromirror arrays.

    PubMed

    Sicker, Cornelius; Heber, Jörg; Berndt, Dirk

    2016-06-01

    Spatial light modulators (SLMs) support flexible system concepts in modern optics and especially phase-only SLMs such as micromirror arrays (MMAs) appear attractive for many applications. In order to achieve a precise phase modulation, which is crucial for optical performance, careful characterization and calibration of SLM devices is required. We examine an intensity-based measurement concept, which promises distinct advantages by means of a spatially resolved scatter measurement that is combined with the MMA's diffractive principle. Measurements yield quantitative results, which are consistent with measurements of micromirror roughness components, by white-light interferometry. They reveal relative scatter as low as 10-4, which corresponds to contrast ratios up to 10,000. The potential of the technique to resolve phase changes in the subnanometer range is experimentally demonstrated. PMID:27411205

  14. Spatially resolved absolute spectrophotometry of Saturn - 3390 to 8080 A

    NASA Technical Reports Server (NTRS)

    Bergstralh, J. T.; Diner, D. J.; Baines, K. H.; Neff, J. S.; Allen, M. A.; Orton, G. S.

    1981-01-01

    A series of spatially resolved absolute spectrophotometric measurements of Saturn was conducted for the expressed purpose of calibrating the data obtained with the Imaging Photopolarimeter (IPP) on Pioneer 11 during its recent encounter with Saturn. All observations reported were made at the Mt. Wilson 1.5-m telescope, using a 1-m Ebert-Fastie scanning spectrometer. Spatial resolution was 1.92 arcsec. Photometric errors are considered, taking into account the fixed error, the variable error, and the composite error. The results are compared with earlier observations, as well as with synthetic spectra derived from preliminary physical models, giving attention to the equatorial region and the South Temperate Zone.

  15. Spatially resolved concentration measurements based on backscatter absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Ze; Sanders, Scott T.; Robinson, Michael A.

    2016-06-01

    We demonstrate the feasibility of spatially resolved measurements of gas properties using direct absorption spectroscopy in conjunction with backscattered signals. We report a 1-D distribution of H2O mole fraction with a spatial resolution of 5 mm. The peak and average discrepancy between the measured and expected mole fraction are 21.1 and 8.0 %, respectively. The demonstration experiment is related to a diesel aftertreatment system; a selective catalytic reduction brick made of cordierite is used. The brick causes volume scattering interference; advanced baseline fitting based on a genetic algorithm is used to reduce the effects of this interference by a factor of 2.3.

  16. Spatially resolved spectrometer system for the ZT-40 device

    SciTech Connect

    Watt, R.G.

    1981-05-01

    A spatially resolved emission spectroscopy system designed for use on the ZT-40 device at the Los Alamos National Laboratory is described. The three-chord system consists of independent dispersive elements and detectors for each chord, on a common wavelength drive. The system has been installed and is currently in use on ZT-40. Preliminary results of CV (227.1 nm) line radiation measurements are presented.

  17. The Spatially-Resolved Star Formation History of the M31 Disk from Resolved Stellar Populations

    NASA Astrophysics Data System (ADS)

    Lewis, Alexia R.; Dalcanton, Julianne J.; Dolphin, Andrew E.; Weisz, Daniel R.; Williams, Benjamin F.

    2015-02-01

    The Panchromatic Hubble Andromeda Treasury (PHAT) is an HST multi-cycle treasury program that has mapped the resolved stellar populations of ~1/3 of the disk of M31 from the UV through the near-IR. This data provides color and luminosity information for more than 150 million stars. Using stellar evolution models, we model the optical color-magnitude diagram to derive spatially-resolved recent star formation histories (SFHs) over large areas of M31 with 100 pc resolution. These include individual star-forming regions as well as quiescent portions of the disk. With these gridded SFHs, we create movies of star formation activity to study the evolution of individual star-forming events across the disk. We analyze the structure of star formation and examine the relation between star formation and gas throughout the disk and particularly in the 10-kpc star-forming ring. We find that the ring has been continuously forming stars for at least 500 Myr. As the only large disk galaxy that is close enough to obtain the photometry for this type of spatially-resolved SFH mapping, M31 plays an important role in our understanding of the evolution of an L* galaxy.

  18. Resolving the temporal-spatial ambiguity with the Auroral Spatial Structures Probe

    NASA Astrophysics Data System (ADS)

    Farr, Daniel

    The Auroral Spatial Structures Probe (ASSP) is a National Aeronautics and Space Administration (NASA) sounding rocket mission to measure small scale temporal and spatial variations in the Earth's electric and magnetic fields during breakup aurora conditions. Multiple time-separated measurements of the same spatial location must be made in order to resolve the temporal-spatial ambiguity. ASSP achieves multipoint measurements by ejecting a constellation of six subpayloads from the main payload. This thesis develops a method for identifying the optimal ejection vector, propose an automated test plan for calibrating the seven payloads, and discuss several challenges relating to the interpretation of ASSP data.

  19. Spatially resolved photoluminescence study of single ZnO tetrapods.

    PubMed

    Feng, L; Cheng, C; Lei, M; Wang, N; Loy, M M T

    2008-10-01

    ZnO tetrapods and nanowires were fabricated by a simple method of thermal evaporation of pure Zn powder in the air. These nanostructures, formed in different temperature regions of the same apparatus, displayed distinct photoluminescence (PL) characteristics. Spatially resolved PL measurements on legs of individual tetrapods show that the green luminescence (GL) decreases with decreasing leg diameter, and there was no detectable GL from nanowires grown simultaneously. These PL properties suggest that the green luminescence may not come from surface states, but rather from bulk defects. PMID:21832631

  20. Development of a Spatially-Resolved Microwave Interferometer

    NASA Astrophysics Data System (ADS)

    Specht, Paul; Cooper, Marcia

    2015-06-01

    The development of a spatially-resolved microwave interferometer (SRMI) for non-invasively measuring the internal transit of a shock, detonation, or reaction front in energetic media is presented. Utilizing the transparency of many energetic materials in the RF regime, current microwave interferometers provide continuum-level tracking of the dielectric discontinuity that occurs across a shock or reaction front. While this continuum-level response can provide bulk shock and detonation velocities, it is insufficient to understand the complex wave and material interactions present in heterogeneous energetic materials. Leveraging interferometry and terahertz spectroscopy techniques, a heterodyne, spatially-resolved microwave interferometer was designed. A theoretical description of its operation and potential impact to current energetic materials research is discussed. Preliminary experimental results, including electro-optic sensing of a Doppler shifted microwave beam, are presented. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2015-0308A.

  1. Spatially resolved heat release rate measurements in turbulent premixed flames

    SciTech Connect

    Ayoola, B.O.; Kaminski, C.F.; Balachandran, R.; Mastorakos, E.; Frank, J.H.

    2006-01-01

    Heat release rate is a fundamental property of great importance for the theoretical and experimental elucidation of unsteady flame behaviors such as combustion noise, combustion instabilities, and pulsed combustion. Investigations of such thermoacoustic interactions require a reliable indicator of heat release rate capable of resolving spatial structures in turbulent flames. Traditionally, heat release rate has been estimated via OH or CH radical chemiluminescence; however, chemiluminescence suffers from being a line-of-sight technique with limited capability for resolving small-scale structures. In this paper, we report spatially resolved two-dimensional measurements of a quantity closely related to heat release rate. The diagnostic technique uses simultaneous OH and CH{sub 2}O planar laser-induced fluorescence (PLIF), and the pixel-by-pixel product of the OH and CH{sub 2}O PLIF signals has previously been shown to correlate well with local heat release rates. Results from this diagnostic technique, which we refer to as heat release rate imaging (HR imaging), are compared with traditional OH chemiluminescence measurements in several flames. Studies were performed in lean premixed ethylene flames stabilized between opposed jets and with a bluff body. Correlations between bulk strain rates and local heat release rates were obtained and the effects of curvature on heat release rate were investigated. The results show that the heat release rate tends to increase with increasing negative curvature for the flames investigated for which Lewis numbers are greater than unity. This correlation becomes more pronounced as the flame gets closer to global extinction.

  2. Spatially Resolved Quantification of the Surface Reactivity of Solid Catalysts.

    PubMed

    Huang, Bing; Xiao, Li; Lu, Juntao; Zhuang, Lin

    2016-05-17

    A new property is reported that accurately quantifies and spatially describes the chemical reactivity of solid surfaces. The core idea is to create a reactivity weight function peaking at the Fermi level, thereby determining a weighted summation of the density of states of a solid surface. When such a weight function is defined as the derivative of the Fermi-Dirac distribution function at a certain non-zero temperature, the resulting property is the finite-temperature chemical softness, termed Fermi softness (SF ), which turns out to be an accurate descriptor of the surface reactivity. The spatial image of SF maps the reactive domain of a heterogeneous surface and even portrays morphological details of the reactive sites. SF analyses reveal that the reactive zones on a Pt3 Y(111) surface are the platinum sites rather than the seemingly active yttrium sites, and the reactivity of the S-dimer edge of MoS2 is spatially anisotropic. Our finding is of fundamental and technological significance to heterogeneous catalysis and industrial processes demanding rational design of solid catalysts. PMID:27072349

  3. Monochromated, spatially resolved electron energy-loss spectroscopic measurements of gold nanoparticles in the plasmon range.

    PubMed

    Schaffer, B; Riegler, K; Kothleitner, G; Grogger, W; Hofer, F

    2009-02-01

    Gold nanoparticles show optical properties different from bulk material due to resonance phenomena which depend on local structure and geometry. Electron energy-loss spectrometry (EELS) in scanning transmission electron microscopy (STEM) allows the spatially resolved measurement of these properties at a resolution of few nanometers. In this work, the first monochromated measurements of gold nanoparticles (spheres, rods and triangles) are presented. Due to the improved energy resolution of about 0.2 eV, surface plasmon excitations at energies below 1 eV could be accurately measured from raw experimental data. PMID:18722779

  4. Spatially resolved optoelectronic characterization of perovskite lead iodide nanostructures

    NASA Astrophysics Data System (ADS)

    Xiao, Rui; Peng, Xingyu; Hou, Yasen; Yu, Dong

    The high power conversion efficiency of organo-lead halide perovskite-based solar cells has attracted world-wide attention over the past few years. The high efficiency was believed to originate from the unusual properties including long carrier lifetimes and consequent long carrier diffusion lengths in these materials. Ion drift, ferroelectricity, and charge traps have been proposed to account for the efficient charge separation and photocurrent hysteresis. However, it remains unclear which mechanism is dominating. We fabricate field effect transistors (FETs) incorporating single nanoplates/nanowires of organic perovskite and perform scanning photocurrent microscopic (SPCM) measurements to extract carrier diffusion lengths as a function of gate voltage, source-drain bias. Spatially resolved optoelectronic investigations of single crystalline perovskite nanostructures provide valuable information and key evidence on distinguishing the dominating charge transport/separation mechanism.

  5. Spatially Resolved Spectrum of the TW Hydrae Circumstellar Disk

    NASA Astrophysics Data System (ADS)

    Roberge, Aki; Weinberger, Alycia J.; Malumuth, Eliot

    2004-06-01

    We present the first spatially resolved spectrum of scattered light from the TW Hydrae protoplanetary disk. This nearly face-on disk is optically thick, surrounding a classical T-Tauri star in the nearby 8 Myr old TW Hya association. Accretion of disk material onto the central star is still occurring, but there are signs that growth of planetary material has begun. Our HST-STIS spectrum covers the optical bandpass from 5000 Å to 1 μm. After careful subtraction of a PSF star spectrum, spectra can be extracted between 37 AU and about 124 AU from the star. The scattered light spectra have the same color as the star (gray scattering) at all radii, except possibly the very innermost region. This likely indicates that either the scattering dust grains are much larger than 1 μm throughout the bulk of the disk or that the disk remains very optically thick out to 124 AU.

  6. Spatially and temporally resolved temperature measurement in laser media.

    PubMed

    Körner, Jörg; Yue, Fangxin; Hein, Joachim; Kaluza, Malte C

    2016-06-01

    A technique to measure the spatially resolved temperature distribution in a laser medium is presented. It is based on the temperature dependence of the absorption cross section close to the zero-phonon line of the active medium. Since other materials in the beam path exhibit a high (and constant) transmission at this wavelength, the method can easily be applied in realistic amplifier setups. The method was successfully tested on three different samples, which were pumped by a pulsed laser diode with up to 150 W average power: side-cooled Yb:YAG and Yb:fluoride-phosphate glass at room temperature and face-cooled Yb:CaF2 at 120 K. PMID:27244405

  7. Spatially resolved study of primary electron transport in magnetic cusps

    SciTech Connect

    Hubble, Aimee A.; Foster, John E.

    2012-01-15

    Spatially resolved primary electron current density profiles were measured using a planar Langmuir probe in the region above a magnetic cusp in a small ion thruster discharge chamber. The probe current maps obtained were used to study the electron collection mechanics in the cusp region in the limit of zero gas flow and no plasma production, and they allowed for the visualization of primary electron transport through the cusp. Attenuation coefficients and loss widths were calculated as a function of probe distance above the anode at various operating conditions. Finally, the collection mechanics between two magnetic cusps were studied and compared. It was found that primary electron collection was dominated by the upstream magnet ring.

  8. Spatially resolved tunneling spectroscopy on TTF-TCNQ

    NASA Astrophysics Data System (ADS)

    Wang, Z. Z.; Girard, J. C.; Pasquier, C.; Jérome, D.

    2004-04-01

    Local tunneling spectroscopy has been measured with low temperature UHV-STM on in-situ cleaved ab surface of organic TTF-TCNQ crystal. Due to ultra low image drift and clear molecular resolution, the spectroscopy is performed at specific molecular site either on TCNQ or TTF chains. In normal state (T= 63 K), a large pseudo-gap exists both in TTF and TCNQ chains. Above pseudo-gap local density of states differs for TTF and TCNQ chains that is in good agreement with double band model. By the signature of an anomalous in local spectroscopy measurement, a single impurity has been detected on a TTF chain. Charge density wave fluctuation is pinned by impurity above critical temperature (T=54K). Results obtained show that, Scanning Tunneling Spectroscopy can provide spatially resolved spectroscopic information at nanometer scale. Key words. TTF-TCNQ, local tunneling spectroscopy, pseudogap.

  9. Spatially Resolved Electronic Structures of Atomically Precise Armchair Graphene Nanoribbons

    NASA Astrophysics Data System (ADS)

    Huang, Han; Wei, Dacheng; Sun, Jiatao; Wong, Swee Liang; Feng, Yuan Ping; Neto, A. H. Castro; Wee, Andrew Thye Shen

    2012-12-01

    Graphene has attracted much interest in both academia and industry. The challenge of making it semiconducting is crucial for applications in electronic devices. A promising approach is to reduce its physical size down to the nanometer scale. Here, we present the surface-assisted bottom-up fabrication of atomically precise armchair graphene nanoribbons (AGNRs) with predefined widths, namely 7-, 14- and 21-AGNRs, on Ag(111) as well as their spatially resolved width-dependent electronic structures. STM/STS measurements reveal their associated electron scattering patterns and the energy gaps over 1 eV. The mechanism to form such AGNRs is addressed based on the observed intermediate products. Our results provide new insights into the local properties of AGNRs, and have implications for the understanding of their electrical properties and potential applications.

  10. Spatially Resolved Electronic Structures of Atomically Precise Armchair Graphene Nanoribbons

    PubMed Central

    Huang, Han; Wei, Dacheng; Sun, Jiatao; Wong, Swee Liang; Feng, Yuan Ping; Neto, A. H. Castro; Wee, Andrew Thye Shen

    2012-01-01

    Graphene has attracted much interest in both academia and industry. The challenge of making it semiconducting is crucial for applications in electronic devices. A promising approach is to reduce its physical size down to the nanometer scale. Here, we present the surface-assisted bottom-up fabrication of atomically precise armchair graphene nanoribbons (AGNRs) with predefined widths, namely 7-, 14- and 21-AGNRs, on Ag(111) as well as their spatially resolved width-dependent electronic structures. STM/STS measurements reveal their associated electron scattering patterns and the energy gaps over 1 eV. The mechanism to form such AGNRs is addressed based on the observed intermediate products. Our results provide new insights into the local properties of AGNRs, and have implications for the understanding of their electrical properties and potential applications. PMID:23248746

  11. Spatially resolved reflectivities of Saturn - 3000-6000 A

    NASA Technical Reports Server (NTRS)

    Cochran, W. D.

    1982-01-01

    Absolute reflectivity reductions are presented for spectrophotometric observations of seven spatially-resolved regions on the disk of Saturn in the 3000-6000 A region. An asymmetry is found between northern and southern hemisphere data, in the equivalent width of the CH4, 5430-A band and in the continuum reflectivity. In addition, the spectra are found not to include the 4700 A reflectivity peak found by Bergstralh et al (1981), and to exhibit general agreement with the Podolack and Danielson (1977) model. The blue and visual spectral region continuum reflectivity of a planetary atmosphere provides constraints for determining aerosol particle single-scattering albedo and vertical distribution, which are in turn important to an understanding of planetary energy balance, atmospheric dynamics, and planetary molecular absorption spectrum interpretation.

  12. Spatially Resolved Star Formation Main Sequence of Galaxies

    NASA Astrophysics Data System (ADS)

    Cano-Díaz, M.; Sánchez, S. F.; Zibetti, S.; Ascaribar, Y.; Bland-Hawthorn, J.; Ziegler, B.; González-Delgado, R. M.; Walcher, C. J.; García-Benito, R.; Mast, D.; Mendoza-Pérez, M. A.; Falcón-Barroso, J.; Galbany, L.; Husemann, B.; Kehring, C.; Marino, R. A.; Sánchez-Blázquez, P.; López-Cobá, C.; López-Sánchez, A. R.; Vilchez, J. M.

    2016-06-01

    The relation known as Star Formation Main Sequence (SFMS) of galaxies is defined in terms of stellar mass and star formation rate. This approximately linear relation has been proven to be tight and holds for several star formation indicators at local and at high redshifts. In this talk I will show recent results about our first attempts to study the Spatially Resolved SFMS, using integral field spectroscopic data, coming primarily from the CALIFA survey. I will present as a main result that a local SFMS is found with a slope and zero point of 0.72 +/ 0.04, and -7.95 +/ 0.29 respectively. I will also discuss the influence of characteristics such as environment and morphology in the relation. Finally I will present some extensions of these results for data com in from the MaNGA survey.

  13. Spatially Resolving Ocean Color and Sediment Dispersion in River Plumes, Coastal Systems, and Continental Shelf Waters

    NASA Technical Reports Server (NTRS)

    Aurin, Dirk Alexander; Mannino, Antonio; Franz, Bryan

    2013-01-01

    Satellite remote sensing of ocean color in dynamic coastal, inland, and nearshorewaters is impeded by high variability in optical constituents, demands specialized atmospheric correction, and is limited by instrument sensitivity. To accurately detect dispersion of bio-optical properties, remote sensors require ample signal-to-noise ratio (SNR) to sense small variations in ocean color without saturating over bright pixels, an atmospheric correction that can accommodate significantwater-leaving radiance in the near infrared (NIR), and spatial and temporal resolution that coincides with the scales of variability in the environment. Several current and historic space-borne sensors have met these requirements with success in the open ocean, but are not optimized for highly red-reflective and heterogeneous waters such as those found near river outflows or in the presence of sediment resuspension. Here we apply analytical approaches for determining optimal spatial resolution, dominant spatial scales of variability ("patches"), and proportions of patch variability that can be resolved from four river plumes around the world between 2008 and 2011. An offshore region in the Sargasso Sea is analyzed for comparison. A method is presented for processing Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra imagery including cloud detection, stray lightmasking, faulty detector avoidance, and dynamic aerosol correction using short-wave- and near-infrared wavebands in extremely turbid regions which pose distinct optical and technical challenges. Results showthat a pixel size of approx. 520 mor smaller is generally required to resolve spatial heterogeneity in ocean color and total suspended materials in river plumes. Optimal pixel size increases with distance from shore to approx. 630 m in nearshore regions, approx 750 m on the continental shelf, and approx. 1350 m in the open ocean. Greater than 90% of the optical variability within plume regions is resolvable with

  14. The properties of spatial resolved ionized gas uncovered by CALIFA

    NASA Astrophysics Data System (ADS)

    Sanchez, Sebastian

    2015-08-01

    We present here the last results we obtained on the spatial resolved analysis of the the stellar populations and ionized gas of disk-dominated galaxies based on CALIFA data. CALIFA is an ongoing IFS survey of galaxies in the Local Univese (0.005spatial resolution better than 1 kpc for a total number of more than 600 galaxies of any morphological type, covering the CM-diagram up to Mr<-18 mag. With nearly 2000 spectra obtained for each galaxy, CALIFA offer one of the best IFU data to study the starformation histories and quemical enrichment of galaxies. In the case of disk-dominated galaxies, we analysed the stellar populations using different inversion methods and line analysis, and the ionized gas identifying the main properties of the HII-regions within the FoV. Both analyisis produce coherent analysis indicating that disk-galaxies growth inside out, with a chemical enrichment dominated by local processes, and limited effects of radial mixing or global outflows.

  15. Developing Accurate Spatial Maps of Cotton Fiber Quality Parameters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Awareness of the importance of cotton fiber quality (Gossypium, L. sps.) has increased as advances in spinning technology require better quality cotton fiber. Recent advances in geospatial information sciences allow an improved ability to study the extent and causes of spatial variability in fiber p...

  16. Multimodal Spatial Calibration for Accurately Registering EEG Sensor Positions

    PubMed Central

    Chen, Shengyong; Xiao, Gang; Li, Xiaoli

    2014-01-01

    This paper proposes a fast and accurate calibration method to calibrate multiple multimodal sensors using a novel photogrammetry system for fast localization of EEG sensors. The EEG sensors are placed on human head and multimodal sensors are installed around the head to simultaneously obtain all EEG sensor positions. A multiple views' calibration process is implemented to obtain the transformations of multiple views. We first develop an efficient local repair algorithm to improve the depth map, and then a special calibration body is designed. Based on them, accurate and robust calibration results can be achieved. We evaluate the proposed method by corners of a chessboard calibration plate. Experimental results demonstrate that the proposed method can achieve good performance, which can be further applied to EEG source localization applications on human brain. PMID:24803954

  17. Multimodal spatial calibration for accurately registering EEG sensor positions.

    PubMed

    Zhang, Jianhua; Chen, Jian; Chen, Shengyong; Xiao, Gang; Li, Xiaoli

    2014-01-01

    This paper proposes a fast and accurate calibration method to calibrate multiple multimodal sensors using a novel photogrammetry system for fast localization of EEG sensors. The EEG sensors are placed on human head and multimodal sensors are installed around the head to simultaneously obtain all EEG sensor positions. A multiple views' calibration process is implemented to obtain the transformations of multiple views. We first develop an efficient local repair algorithm to improve the depth map, and then a special calibration body is designed. Based on them, accurate and robust calibration results can be achieved. We evaluate the proposed method by corners of a chessboard calibration plate. Experimental results demonstrate that the proposed method can achieve good performance, which can be further applied to EEG source localization applications on human brain. PMID:24803954

  18. Calibration and analysis of spatially resolved x-ray absorption spectra from a nonuniform plasma

    SciTech Connect

    Knapp, P. F.; Hansen, S. B.; Pikuz, S. A.; Shelkovenko, T. A.; Hammer, D. A.

    2012-07-15

    We report here the calibration and analysis techniques used to obtain spatially resolved density and temperature measurements of a pair of imploding aluminum wires from x-ray absorption spectra. A step wedge is used to measure backlighter fluence at the film, allowing transmission through the sample to be measured with an accuracy of {+-}14% or better. A genetic algorithm is used to search the allowed plasma parameter space and fit synthetic spectra with 20 {mu}m spatial resolution to the measured spectra, taking into account that the object plasma nonuniformity must be physically reasonable. The inferred plasma conditions must be allowed to vary along the absorption path in order to obtain a fit to the spectral data. The temperature is estimated to be accurate to within {+-}25% and the density to within a factor of two. This information is used to construct two-dimensional maps of the density and temperature of the object plasma.

  19. Calibration and analysis of spatially resolved x-ray absorption spectra from a nonuniform plasma.

    PubMed

    Knapp, P F; Hansen, S B; Pikuz, S A; Shelkovenko, T A; Hammer, D A

    2012-07-01

    We report here the calibration and analysis techniques used to obtain spatially resolved density and temperature measurements of a pair of imploding aluminum wires from x-ray absorption spectra. A step wedge is used to measure backlighter fluence at the film, allowing transmission through the sample to be measured with an accuracy of ±14% or better. A genetic algorithm is used to search the allowed plasma parameter space and fit synthetic spectra with 20 μm spatial resolution to the measured spectra, taking into account that the object plasma nonuniformity must be physically reasonable. The inferred plasma conditions must be allowed to vary along the absorption path in order to obtain a fit to the spectral data. The temperature is estimated to be accurate to within ±25% and the density to within a factor of two. This information is used to construct two-dimensional maps of the density and temperature of the object plasma. PMID:22852690

  20. Study of Spatially Resolved Temperature Diagnostics for High Explosives

    SciTech Connect

    Lee, H

    2000-04-05

    The next generation of 2-D and 3-D weapon-simulation codes will require marked advances in the spatial and temporal resolution of the various diagnostics to verify the complex physics predicted from these calculations. This is particularly true for the complicated physics of high-explosive (HE) detonation and burn, of which a detailed understanding is crucial to nuclear weapons performance and integrity. The processes involved in the detonation of HEs occur very rapidly and lead to extremely high pressures (several GPa) and temperatures (several thousand Kelvin). A key diagnostic that has so far eluded experimentalists is a temperature diagnostic for burning HE. Temperature is a basic thermodynamic property that enables a fundamental understanding of important HE physics such as the chemical processes involved in the shock-to-detonation transition, and to assess the thermal part of the equation-of-state of the detonation products. Accurate, spatially localized temperature measurements with high temporal resolution are thus crucial, but are unfortunately lacking. Our work address this important problem.

  1. Spatially resolved breakdown in reentrant quantum Hall states

    NASA Astrophysics Data System (ADS)

    Rossokhaty, Oleksandr; Folk, Joshua; Baum, Yuval; Stern, Ady; Watson, John; Gardner, Geoffrey; Manfra, Michael

    Electrons in a two dimensional electron gas in the fractional quantum Hall regime may rearrange into a quasi-crystalline structure that gives rise to a reentrant Integer Quantum Hall (RIQH) effect in transport. As bias current increases, longitudinal and Hall resistivities measured for these states show multiple sharp breakdown transitions, a signature that is unique to RIQH states and has previously been ascribed to pinning-depinning transitions or to the development of bias-induced anisotropy. We present an alternate interpretation of the characteristic features of RIQH breakdown at high bias, based on spatially-resolved measurements that indicate a phase boundary between broken-down and unbroken regions propagating chirally from source and drain contacts as a function of bias current. As the phase boundary passes various contacts, its spreading generates multi-stage breakdown signatures like those reported elsewhere. Confirming numerical simulations, the chiral sense of the spreading is set not by the chirality of the edge state itself, but instead depends on electron- or hole-like character of the RIQH state.

  2. DUST GRAIN EVOLUTION IN SPATIALLY RESOLVED T TAURI BINARIES

    SciTech Connect

    Skemer, Andrew J.; Close, Laird M.; Hinz, Philip M.; Hoffmann, William F.; Males, Jared R.; Greene, Thomas P.

    2011-10-10

    Core-accretion planet formation begins in protoplanetary disks with the growth of small, interstellar medium dust grains into larger particles. The progress of grain growth, which can be quantified using 10 {mu}m silicate spectroscopy, has broad implications for the final products of planet formation. Previous studies have attempted to correlate stellar and disk properties with the 10 {mu}m silicate feature in an effort to determine which stars are efficient at grain growth. Thus far there does not appear to be a dominant correlated parameter. In this paper, we use spatially resolved adaptive optics spectroscopy of nine T Tauri binaries as tight as 0.''25 to determine if basic properties shared between binary stars, such as age, composition, and formation history, have an effect on dust grain evolution. We find with 90%-95% confidence that the silicate feature equivalent widths of binaries are more similar than those of randomly paired single stars, implying that shared properties do play an important role in dust grain evolution. At lower statistical significance, we find with 82% confidence that the secondary has a more prominent silicate emission feature (i.e., smaller grains) than the primary. If confirmed by larger surveys, this would imply that spectral type and/or binarity are important factors in dust grain evolution.

  3. Spatially resolved and observer-free experimental quantification of spatial resolution in tomographic images

    SciTech Connect

    Tsekenis, S. A.; McCann, H.; Tait, N.

    2015-03-15

    We present a novel framework and experimental method for the quantification of spatial resolution of a tomography system. The framework adopts the “black box” view of an imaging system, considering only its input and output. The tomography system is locally stimulated with a step input, viz., a sharp edge. The output, viz., the reconstructed images, is analysed by Fourier decomposition of their spatial frequency components, and the local limiting spatial resolution is determined using a cut-off threshold. At no point is an observer involved in the process. The framework also includes a means of translating the quantification region in the imaging space, thus creating a spatially resolved map of objectively quantified spatial resolution. As a case-study, the framework is experimentally applied using a gaseous propane phantom measured by a well-established chemical species tomography system. A spatial resolution map consisting of 28 regions is produced. In isolated regions, the indicated performance is 4-times better than that suggested in the literature and varies by 57% across the imaging space. A mechanism based on adjacent but non-interacting beams is hypothesised to explain the observed behaviour. The mechanism suggests that, as also independently concluded by other methods, a geometrically regular beam array maintains maximum objectivity in reconstructions. We believe that the proposed framework, methodology, and findings will be of value in the design and performance evaluation of tomographic imaging arrays and systems.

  4. A spatially resolved surface kinetic model for forsterite dissolution

    NASA Astrophysics Data System (ADS)

    Maher, Kate; Johnson, Natalie C.; Jackson, Ariel; Lammers, Laura N.; Torchinsky, Abe B.; Weaver, Karrie L.; Bird, Dennis K.; Brown, Gordon E.

    2016-02-01

    The development of complex alteration layers on silicate mineral surfaces undergoing dissolution is a widely observed phenomenon. Given the complexity of these layers, most kinetic models used to predict rates of mineral-fluid interactions do not explicitly consider their formation. As a result, the relationship between the development of the altered layers and the final dissolution rate is poorly understood. To improve our understanding of the relationship between the alteration layer and the dissolution rate, we developed a spatially resolved surface kinetic model for olivine dissolution and applied it to a series of closed-system experiments consisting of three-phases (water (±NaCl), olivine, and supercritical CO2) at conditions relevant to in situ mineral carbonation (i.e. 60 °C, 100 bar CO2). We also measured the corresponding δ26/24Mg of the dissolved Mg during early stages of dissolution. Analysis of the solid reaction products indicates the formation of Mg-depleted layers on the olivine surface as quickly as 2 days after the experiment was started and before the bulk solution reached saturation with respect to amorphous silica. The δ26/24Mg of the dissolved Mg decreased by approximately 0.4‰ in the first stages of the experiment and then approached the value of the initial olivine (-0.35‰) as the steady-state dissolution rate was approached. We attribute the preferential release of 24Mg to a kinetic effect associated with the formation of a Mg-depleted layer that develops as protons exchange for Mg2+. We used experimental data to calibrate a surface kinetic model for olivine dissolution that includes crystalline olivine, a distinct "active layer" from which Mg can be preferentially removed, and secondary amorphous silica precipitation. By coupling the spatial arrangement of ions with the kinetics, this model is able to reproduce both the early and steady-state long-term dissolution rates, and the kinetic isotope fractionation. In the early stages of

  5. The Lyman alpha reference sample. VII. Spatially resolved Hα kinematics

    NASA Astrophysics Data System (ADS)

    Herenz, Edmund Christian; Gruyters, Pieter; Orlitova, Ivana; Hayes, Matthew; Östlin, Göran; Cannon, John M.; Roth, Martin M.; Bik, Arjan; Pardy, Stephen; Otí-Floranes, Héctor; Mas-Hesse, J. Miguel; Adamo, Angela; Atek, Hakim; Duval, Florent; Guaita, Lucia; Kunth, Daniel; Laursen, Peter; Melinder, Jens; Puschnig, Johannes; Rivera-Thorsen, Thøger E.; Schaerer, Daniel; Verhamme, Anne

    2016-03-01

    We present integral field spectroscopic observations with the Potsdam Multi-Aperture Spectrophotometer of all 14 galaxies in the z ~ 0.1 Lyman Alpha Reference Sample (LARS). We produce 2D line-of-sight velocity maps and velocity dispersion maps from the Balmer α (Hα) emission in our data cubes. These maps trace the spectral and spatial properties of the LARS galaxies' intrinsic Lyα radiation field. We show our kinematic maps that are spatially registered onto the Hubble Space Telescope Hα and Lyman α (Lyα) images. We can conjecture a causal connection between spatially resolved Hα kinematics and Lyα photometry for individual galaxies, however, no general trend can be established for the whole sample. Furthermore, we compute the intrinsic velocity dispersion σ0, the shearing velocity vshear, and the vshear/σ0 ratio from our kinematic maps. In general LARS galaxies are characterised by high intrinsic velocity dispersions (54 km s-1 median) and low shearing velocities (65 km s-1 median). The vshear/σ0 values range from 0.5 to 3.2 with an average of 1.5. It is noteworthy that five galaxies of the sample are dispersion-dominated systems with vshear/σ0< 1, and are thus kinematically similar to turbulent star-forming galaxies seen at high redshift. When linking our kinematical statistics to the global LARS Lyα properties, we find that dispersion-dominated systems show higher Lyα equivalent widths and higher Lyα escape fractions than systems with vshear/σ0> 1. Our result indicates that turbulence in actively star-forming systems is causally connected to interstellar medium conditions that favour an escape of Lyα radiation. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).The reduced data cubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130

  6. Spatially resolved dust emission of extremely metal-poor galaxies*

    NASA Astrophysics Data System (ADS)

    Zhou, Luwenjia; Shi, Yong; Diaz-Santos, Taino; Armus, Lee; Helou, George; Stierwalt, Sabrina; Li, Aigen

    2016-05-01

    We present infrared (IR) spectral energy distributions (SEDs) of individual star-forming regions in four extremely metal-poor (EMP) galaxies with metallicity Z ≲ Z⊙/10 as observed by the Herschel Space Observatory. With the good wavelength coverage of the SED, it is found that these EMP star-forming regions show distinct SED shapes as compared to those of grand design Spirals and higher metallicity dwarfs: they have on average much higher f70μm/f160 μm ratios at a given f160 μm/f250 μm ratio; single modified blackbody (MBB) fittings to the SED at λ ≥ 100 μm still reveal higher dust temperatures and lower emissivity indices compared to that of Spirals, while two MBB fittings to the full SED with a fixed emissivity index (β = 2) show that even at 100 μm, about half of the emission comes from warm (50 K) dust, in contrast to the cold (˜20 K) dust component. Our spatially resolved images furthermore reveal that the far-IR colours including f70 μm/f160 μm, f160 μm/f250 μm and f250 μm/f350 μm are all related to the surface densities of young stars as traced by far-UV, 24 μm and star formation rates (SFRs), but not to the stellar mass surface densities. This suggests that the dust emitting at wavelengths from 70 to 350 μm is primarily heated by radiation from young stars.

  7. THE ALGOL TRIPLE SYSTEM SPATIALLY RESOLVED AT OPTICAL WAVELENGTHS

    SciTech Connect

    Zavala, R. T.; Hutter, D. J.; Hummel, C. A.; Boboltz, D. A.; Ojha, R.; Shaffer, D. B.; Tycner, C.; Richards, M. T. E-mail: djh@nofs.navy.mi E-mail: dboboltz@usno.navy.mi E-mail: shaffer@alumni.caltech.ed E-mail: mrichards@astro.psu.ed

    2010-05-20

    Interacting binaries typically have separations in the milliarcsecond regime, and hence it has been challenging to resolve them at any wavelength. However, recent advances in optical interferometry have improved our ability to discern the components in these systems and have now enabled the direct determination of physical parameters. We used the Navy Prototype Optical Interferometer to produce for the first time images resolving all three components in the well-known Algol triple system. Specifically, we have separated the tertiary component from the binary and simultaneously resolved the eclipsing binary pair, which represents the nearest and brightest eclipsing binary in the sky. We present revised orbital elements for the triple system, and we have rectified the 180{sup 0} ambiguity in the position angle of Algol C. Our directly determined magnitude differences and masses for this triple star system are consistent with earlier light curve modeling results.

  8. Spatially Resolved Spectroscopy of the SNR IC443

    NASA Technical Reports Server (NTRS)

    Gorenstein, P.

    1998-01-01

    investigators examined the spatial structure of the thermal component and analyzed the GIS spectra with a non-equilibrium plasma model, and found no systematic variation of the interstellar absorption across the remnant. Evidence for shock acceleration of cosmic rays to high energies (10 TeV) was found by Keohane. X-ray imaging spectroscopy with ASCA reveals two regions of particularly hard emission: an unresolved source embedded in an extended emission region, and a ridge of emission coincident with the southeastern rim. Both features are located on part of the radio shell where the shock wave is interacting with molecular gas, and together they account for a majority of the emission at 7 keV. Though we would not have noticed it a priori, the unresolved feature is coincident with one resolved by the ROSAT HRI. The ASCA measurements were combined with higher energy data from the XTE and GRO missions and with radio and TeV gamma-ray data to produce a nonthermal multiwavelength spectrum for IC 443 which was fit with a cosmic ray interaction model. This model calculates the cynchrotron, bremsstrahlung, invers Compton, and neutral pion decay emission produced by locally accelerated cosmic ray interacting with ambient matter, soft photon fields, and magnetic fields.

  9. In situ, spatially resolved biosignature detection at the microbial scale

    NASA Astrophysics Data System (ADS)

    Williford, K. H.; Eigenbrode, J. L.; Hallmann, C.; Kitajima, K.; Kozdon, R.; Summons, R. E.; Kudryavstev, A.; Lepot, K.; Schopf, J.; Spicuzza, M.; Sugitani, K.; Ushikubo, T.; van Kranendonk, M.; Valley, J. W.

    2013-12-01

    Whether life has ever existed beyond Earth is one of the great human questions. The Science Definition Team (SDT) for the proposed NASA Mars 2020 rover mission recently announced a suggested approach for NASA to 'demonstrate significant technical progress towards the future return of scientifically selected, well-documented samples to Earth' in part 'to investigate whether Mars was ever inhabited by microbial life.' The SDT further recommended a per-sample volume of 8 cm3 [1] (e.g., a core with a diameter of 1 cm and length of 10 cm). Such samples would be the first available for scientific inquiry with the potential to definitively answer the fundamental question of astrobiology, and their small volume would necessitate analysis with non- or minimally destructive techniques. Potential biosignatures include 'chemical, isotopic, mineralogical, and morphological features that can be created by life and also appear to be inconsistent with nonbiological processes'[1]. Guidelines for biosignature detection in extraterrestrial samples derive in part from the search for evidence of life in the most ancient sedimentary rocks on Earth, wherein the most compelling case for biogenicity is made when these 'chemical, isotopic, mineralogical, and morphological features' occur in association. Sedimentary rocks deposited on Earth prior to ~3.5 billion years ago (i.e., when persistent surface water [e.g., 2] likely supported habitable environments on Mars) have only very rarely escaped severe alteration by metamorphism and metasomatism. Understanding how these processes have operated on Earth through strategic interrogation of biosignature alteration records in (meta)sedimentary rocks is thus a critical task in the search for extraterrestrial life. Here we present techniques for and results of in situ, spatially resolved, non- or minimally destructive detection of morphological, elemental, molecular, and light stable isotopic biosignatures, as well as records of alteration, in

  10. Spatially-resolved X-ray Scattering off shock-compressed carbon at the LCLS

    NASA Astrophysics Data System (ADS)

    Zastrau, Ulf

    2015-06-01

    The diversity of the electronic properties of carbon makes it of key interest to the material science community; nowhere is this more evident than in the myriad potential applications of structured allotropes like grapheme and nano tubes. By contrast, at the high pressures typical of planetary and stellar interiors, the behavior of carbon is poorly understood with large uncertainties in the conductivity and even the material phase. There is growing evidence of the abundance of diamond in the interiors of the ice giant planets Uranus and Neptune; the conductivity of which could potentially influence models for the origin of the unusual magnetic fields of these planets. In laboratory experiments, practical issues with gradients in the temperature and density of shock compressed matter have hindered accurate measurement and further from distinguishing theoretical models. Here, we present spatially resolved x-ray scattering experiments using LCLS free electron laser to examine and understand the gradients of thermal properties under dynamic shock loading. We employed curved mosaic and perfect imaging crystals. Compared with hydro-dynamic simulations, we present time-resolved data on plasmon dispersion, axial compression gradients and finally carbon melting at shock coalescence.

  11. Spatially resolved determination of the short-circuit current density of silicon solar cells via lock-in thermography

    SciTech Connect

    Fertig, Fabian Greulich, Johannes; Rein, Stefan

    2014-05-19

    We present a spatially resolved method to determine the short-circuit current density of crystalline silicon solar cells by means of lock-in thermography. The method utilizes the property of crystalline silicon solar cells that the short-circuit current does not differ significantly from the illuminated current under moderate reverse bias. Since lock-in thermography images locally dissipated power density, this information is exploited to extract values of spatially resolved current density under short-circuit conditions. In order to obtain an accurate result, one or two illuminated lock-in thermography images and one dark lock-in thermography image need to be recorded. The method can be simplified in a way that only one image is required to generate a meaningful short-circuit current density map. The proposed method is theoretically motivated, and experimentally validated for monochromatic illumination in comparison to the reference method of light-beam induced current.

  12. The Spatially Resolved Bipolar Nebula of Sakurai's Object

    NASA Astrophysics Data System (ADS)

    Hinkle, Kenneth H.; Joyce, Richard R.

    2014-04-01

    Sakurai's object (V4334 Sgr), the final flash object discovered in the mid-1990s, underwent rapid cooling during the first decade of the 21st century becoming as faint as K ~ 25. This stage of evolution has ceased. Between observations in 2010 September and 2013 April V4334 Sgr brightened >2 mag to K = 14.2 and the effective temperature increased to ~590 K. AO images show a central source and two extended globules defining a 13° position angle. The globules span a spatial extent of ~0.''3 in 2013. This spatial extent is consistent with sizes derived from spectral energy distributions taken over the previous decade and a debris cloud expanding at 0.055 mas d-1 since late 1998. Near-simultaneous 0.85-2.5 μm spectra reveal helium lines attributed to a wind-interaction shock. The He I 1.0830 μm emission has a spectral width of ~1000 km s-1 and a spatial extent of ~1.''4. The helium shell is fragmented, spatially asymmetric, and five times larger than the dust debris cloud. [C I] and [N I] forbidden lines are present in the 1 μm region spectrum. The forbidden line spectrum is similar to that of proto-planetary nebulae. The [C I] 9850 Å line is spatially extended. The expansion velocity and change of angular size limit the distance to 2.1-3.7 kpc.

  13. Direct-comb molecular spectroscopy with accurate, resolved comb teeth over 43 THz.

    PubMed

    Zolot, A M; Giorgetta, F R; Baumann, E; Nicholson, J W; Swann, W C; Coddington, I; Newbury, N R

    2012-02-15

    We demonstrate a dual-comb spectrometer using stabilized frequency combs spanning 177 to 220 THz (1360 to 1690 nm) in the near infrared. Comb-tooth-resolved measurements of amplitude and phase generate over 4×10(5) individually resolved spectral elements at 100 MHz point spacing and kilohertz-level resolution and accuracy. The signal-to-noise ratio is 100 to 3000 per comb tooth. Doppler-broadened phase and amplitude spectra of CO(2), CH(4), C(2)H(2), and H(2)O in a 30 m multipass cell agree with established spectral parameters, achieving high-resolution measurements with optical bandwidth generally associated with blackbody sources. PMID:22344132

  14. Spatially resolved, highly multiplexed RNA profiling in single cells

    PubMed Central

    Chen, Kok Hao; Boettiger, Alistair N.; Moffitt, Jeffrey R.; Wang, Siyuan; Zhuang, Xiaowei

    2015-01-01

    Knowledge of the expression profile and spatial landscape of the transcriptome in individual cells is essential for understanding the rich repertoire of cellular behaviors. Here we report multiplexed error-robust fluorescence in situ hybridization (MERFISH), a single-molecule imaging approach that allows the copy numbers and spatial localizations of thousands of RNA species to be determined in single cells. Using error-robust encoding schemes to combat single-molecule labeling and detection errors, we demonstrated the imaging of 100 – 1000 unique RNA species in hundreds of individual cells. Correlation analysis of the ~104 – 106 pairs of genes allowed us to constrain gene regulatory networks, predict novel functions for many unannotated genes, and identify distinct spatial distribution patterns of RNAs that correlate with properties of the encoded proteins. PMID:25858977

  15. Spatial Grouping Resolves Ambiguity to Drive Temporal Recalibration

    ERIC Educational Resources Information Center

    Yarrow, Kielan; Roseboom, Warrick; Arnold, Derek H.

    2011-01-01

    Cross-modal temporal recalibration describes a shift in the point of subjective simultaneity (PSS) between 2 events following repeated exposure to asynchronous cross-modal inputs--the adaptors. Previous research suggested that audiovisual recalibration is insensitive to the spatial relationship between the adaptors. Here we show that audiovisual…

  16. The spatially resolved bipolar nebula of Sakurai's object

    SciTech Connect

    Hinkle, Kenneth H.; Joyce, Richard R. E-mail: rjoyce@noao.edu

    2014-04-20

    Sakurai's object (V4334 Sgr), the final flash object discovered in the mid-1990s, underwent rapid cooling during the first decade of the 21st century becoming as faint as K ∼ 25. This stage of evolution has ceased. Between observations in 2010 September and 2013 April V4334 Sgr brightened >2 mag to K = 14.2 and the effective temperature increased to ∼590 K. AO images show a central source and two extended globules defining a 13° position angle. The globules span a spatial extent of ∼0.''3 in 2013. This spatial extent is consistent with sizes derived from spectral energy distributions taken over the previous decade and a debris cloud expanding at 0.055 mas d{sup –1} since late 1998. Near-simultaneous 0.85-2.5 μm spectra reveal helium lines attributed to a wind-interaction shock. The He I 1.0830 μm emission has a spectral width of ∼1000 km s{sup –1} and a spatial extent of ∼1.''4. The helium shell is fragmented, spatially asymmetric, and five times larger than the dust debris cloud. [C I] and [N I] forbidden lines are present in the 1 μm region spectrum. The forbidden line spectrum is similar to that of proto-planetary nebulae. The [C I] 9850 Å line is spatially extended. The expansion velocity and change of angular size limit the distance to 2.1-3.7 kpc.

  17. An efficient and accurate approach to MTE-MART for time-resolved tomographic PIV

    NASA Astrophysics Data System (ADS)

    Lynch, K. P.; Scarano, F.

    2015-03-01

    The motion-tracking-enhanced MART (MTE-MART; Novara et al. in Meas Sci Technol 21:035401, 2010) has demonstrated the potential to increase the accuracy of tomographic PIV by the combined use of a short sequence of non-simultaneous recordings. A clear bottleneck of the MTE-MART technique has been its computational cost. For large datasets comprising time-resolved sequences, MTE-MART becomes unaffordable and has been barely applied even for the analysis of densely seeded tomographic PIV datasets. A novel implementation is proposed for tomographic PIV image sequences, which strongly reduces the computational burden of MTE-MART, possibly below that of regular MART. The method is a sequential algorithm that produces a time-marching estimation of the object intensity field based on an enhanced guess, which is built upon the object reconstructed at the previous time instant. As the method becomes effective after a number of snapshots (typically 5-10), the sequential MTE-MART (SMTE) is most suited for time-resolved sequences. The computational cost reduction due to SMTE simply stems from the fewer MART iterations required for each time instant. Moreover, the method yields superior reconstruction quality and higher velocity field measurement precision when compared with both MART and MTE-MART. The working principle is assessed in terms of computational effort, reconstruction quality and velocity field accuracy with both synthetic time-resolved tomographic images of a turbulent boundary layer and two experimental databases documented in the literature. The first is the time-resolved data of flow past an airfoil trailing edge used in the study of Novara and Scarano (Exp Fluids 52:1027-1041, 2012); the second is a swirling jet in a water flow. In both cases, the effective elimination of ghost particles is demonstrated in number and intensity within a short temporal transient of 5-10 frames, depending on the seeding density. The increased value of the velocity space

  18. Spatially resolved SO2 flux emissions from Mt Etna

    NASA Astrophysics Data System (ADS)

    D'Aleo, R.; Bitetto, M.; Delle Donne, D.; Tamburello, G.; Battaglia, A.; Coltelli, M.; Patanè, D.; Prestifilippo, M.; Sciotto, M.; Aiuppa, A.

    2016-07-01

    We report on a systematic record of SO2 flux emissions from individual vents of Etna volcano (Sicily), which we obtained using a permanent UV camera network. Observations were carried out in summer 2014, a period encompassing two eruptive episodes of the New South East Crater (NSEC) and a fissure-fed eruption in the upper Valle del Bove. We demonstrate that our vent-resolved SO2 flux time series allow capturing shifts in activity from one vent to another and contribute to our understanding of Etna's shallow plumbing system structure. We find that the fissure eruption contributed ~50,000 t of SO2 or ~30% of the SO2 emitted by the volcano during the 5 July to 10 August eruptive interval. Activity from this eruptive vent gradually vanished on 10 August, marking a switch of degassing toward the NSEC. Onset of degassing at the NSEC was a precursory to explosive paroxysmal activity on 11-15 August.

  19. Spatially resolved micro-photoluminescence imaging of porphyrin single crystals

    NASA Astrophysics Data System (ADS)

    Marin, Dawn M.; Castaneda, Jose; Kaushal, Meesha; Kaouk, Ghallia; Jones, Daniel S.; Walter, Michael G.

    2016-08-01

    We describe the collection of both time-resolved and steady-state micro-photoluminescence data from solution-grown single crystals of 5,15-bis(4-carbomethoxyphenyl)porphyrin (BCM2PP). Linking molecular orientation and structure with excited-state dynamics is crucial for engineering efficient organic solar cells, light-emitting diodes, and related molecular electronics. Photoluminescence features of single porphyrin crystals were imaged using a laser scanning confocal microscope equipped with time-correlated single photon counting (TCSPC). We show enhanced exciton lifetimes (τs1 = 2.6 ns) and stronger steady-state emission in crystalline BCM2PP samples relative to semicrystalline thin films (τs1 = 1.8 ns).

  20. Quantitative spatially resolved measurements of mass transfer through laryngeal cartilage.

    PubMed

    Macpherson, J V; O'Hare, D; Unwin, P R; Winlove, C P

    1997-11-01

    The scanning electrochemical microscope (SECM) is a scanned probe microscope that uses the response of a mobile ultramicroelectrode (UME) tip to determine the reactivity, topography, and mass transport characteristics of interfaces with high spatial resolution. SECM strategies for measuring the rates of solute diffusion and convection through samples of cartilage, using amperometric UMEs, are outlined. The methods are used to determine the diffusion coefficients of oxygen and ruthenium(III) hexamine [Ru(NH3)6(3+)] in laryngeal cartilage. The diffusion coefficient of oxygen in cartilage is found to be approximately 50% of that in aqueous electrolyte solution, assuming a partition coefficient of unity for oxygen between cartilage and aqueous solution. In contrast, diffusion of Ru(NH3)6(3+) within the cartilage sample cannot be detected on the SECM timescale, suggesting a diffusion coefficient at least two orders of magnitude lower than that in solution, given a measured partition coefficient for Ru(NH3)6(3+) between cartilage and aqueous solution, Kp = [Ru(NH3)6(3+)]cartilage/[RU(NH3)6(3+)]solution = 3.4 +/- 0.1. Rates of Ru(NH3)6(3+) osmotically driven convective transport across cartilage samples are imaged at high spatial resolution by monitoring the current response of a scanning UME, with an osmotic pressure of approximately 0.75 atm across the slice. A model is outlined that enables the current response to be related to the local flux. By determining the topography of the sample from the current response with no applied osmotic pressure, local transport rates can be correlated with topographical features of the sample surface, at much higher spatial resolution than has previously been achieved. PMID:9370471

  1. Quantitative spatially resolved measurements of mass transfer through laryngeal cartilage.

    PubMed Central

    Macpherson, J V; O'Hare, D; Unwin, P R; Winlove, C P

    1997-01-01

    The scanning electrochemical microscope (SECM) is a scanned probe microscope that uses the response of a mobile ultramicroelectrode (UME) tip to determine the reactivity, topography, and mass transport characteristics of interfaces with high spatial resolution. SECM strategies for measuring the rates of solute diffusion and convection through samples of cartilage, using amperometric UMEs, are outlined. The methods are used to determine the diffusion coefficients of oxygen and ruthenium(III) hexamine [Ru(NH3)6(3+)] in laryngeal cartilage. The diffusion coefficient of oxygen in cartilage is found to be approximately 50% of that in aqueous electrolyte solution, assuming a partition coefficient of unity for oxygen between cartilage and aqueous solution. In contrast, diffusion of Ru(NH3)6(3+) within the cartilage sample cannot be detected on the SECM timescale, suggesting a diffusion coefficient at least two orders of magnitude lower than that in solution, given a measured partition coefficient for Ru(NH3)6(3+) between cartilage and aqueous solution, Kp = [Ru(NH3)6(3+)]cartilage/[RU(NH3)6(3+)]solution = 3.4 +/- 0.1. Rates of Ru(NH3)6(3+) osmotically driven convective transport across cartilage samples are imaged at high spatial resolution by monitoring the current response of a scanning UME, with an osmotic pressure of approximately 0.75 atm across the slice. A model is outlined that enables the current response to be related to the local flux. By determining the topography of the sample from the current response with no applied osmotic pressure, local transport rates can be correlated with topographical features of the sample surface, at much higher spatial resolution than has previously been achieved. Images FIGURE 6 FIGURE 7 FIGURE 8 PMID:9370471

  2. Spatially resolved resonant tunneling on single atoms in silicon.

    PubMed

    Voisin, B; Salfi, J; Bocquel, J; Rahman, R; Rogge, S

    2015-04-22

    The ability to control single dopants in solid-state devices has opened the way towards reliable quantum computation schemes. In this perspective it is essential to understand the impact of interfaces and electric fields, inherent to address coherent electronic manipulation, on the dopants atomic scale properties. This requires both fine energetic and spatial resolution of the energy spectrum and wave-function, respectively. Here we present an experiment fulfilling both conditions: we perform transport on single donors in silicon close to a vacuum interface using a scanning tunneling microscope (STM) in the single electron tunneling regime. The spatial degrees of freedom of the STM tip provide a versatility allowing a unique understanding of electrostatics. We obtain the absolute energy scale from the thermal broadening of the resonant peaks, allowing us to deduce the charging energies of the donors. Finally we use a rate equations model to derive the current in presence of an excited state, highlighting the benefits of the highly tunable vacuum tunnel rates which should be exploited in further experiments. This work provides a general framework to investigate dopant-based systems at the atomic scale. PMID:25782866

  3. Spatially Resolved Monitoring of Drying of Hierarchical Porous Organic Networks.

    PubMed

    Velasco, Manuel Isaac; Silletta, Emilia V; Gomez, Cesar G; Strumia, Miriam C; Stapf, Siegfried; Monti, Gustavo Alberto; Mattea, Carlos; Acosta, Rodolfo H

    2016-03-01

    Evaporation kinetics of water confined in hierarchal polymeric porous media is studied by low field nuclear magnetic resonance (NMR). Systems synthesized with various degrees of cross-linker density render networks with similar pore sizes but different response when soaked with water. Polymeric networks with low percentage of cross-linker can undergo swelling, which affects the porosity as well as the drying kinetics. The drying process is monitored macroscopically by single-sided NMR, with spatial resolution of 100 μm, while microscopic information is obtained by measurements of spin-spin relaxation times (T2). Transition from a funicular to a pendular regime, where hydraulic connectivity is lost and the capillary flow cannot compensate for the surface evaporation, can be observed from inspection of the water content in different sample layers. Relaxation measurements indicate that even when the larger pore structures are depleted of water, capillary flow occurs through smaller voids. PMID:26847003

  4. Spatially resolved chemical reaction monitoring using magnetic resonance imaging.

    PubMed

    Feindel, Kirk W

    2016-06-01

    Over the previous three decades, the use of MRI for studying dynamic physical and chemical processes of materials systems has grown significantly. This mini-review provides a brief introduction to relevant principles of MRI, including methods of spatial localization, factors contributing to image contrast, and chemical shift imaging. A few historical examples of (1) H MRI for reaction monitoring will be presented, followed by a review of recent research including (1) H MRI studies of gelation and biofilms, (1) H, (7) Li, and (11) B MRI studies of electrochemical systems, in vivo glucose metabolism monitored with (19) F MRI, and in situ temperature monitoring with (27) Al MRI. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25589470

  5. Spatially resolved spectroscopy of young supernova remnants observed with Chandra

    NASA Astrophysics Data System (ADS)

    Stage, M. D.; Allen, G. E.; Houck, J. C.

    The Advanced CCD Imaging Spectrometer (ACIS) detectors on Chandra have captured the highest resolution X-ray images of several supernova remnants. These images of the shocks, filaments and interactions of the supernova shell with the interstellar medium (or in some cases central objects) are spectacular not only for the incredible imaging clarity they provide, but perhaps more so for the integrated spectral information they contain. Yet the volume of this spatial and spectral data--reaching a new extreme with the megasecond observation of Cassiopeia A this spring--can provide a challenge for analysis. Using a suite of software tools developed for use with the ISIS spectral fitting package, and utilzing distributed processing, we have mapped the variation of spectral line and continnum features throughout the Cassiopeia A and other supernova remnants. We present maps of the elemental distribution, distribution of thermal and non-thermal emission, and plasma temperatures for tens of thousands of individual regions in the remnants. These maps include the results of an analysis of the new megasecond observation of Cas A.

  6. Spatially-Resolved Imaging of Stripped-Envelope Supernova Environments

    NASA Astrophysics Data System (ADS)

    Van Dyk, Schuyler Dana

    2015-08-01

    Stripped-envelope supernovae (SNe), i.e., those of Type Ib, Ic, and IIb, arise from massive progenitor stars which have had most or all of their outer hydrogen-rich layers removed before explosion by some process, either through a strong stellar wind or through binary mass transfer. The connection between some long-duration gamma-ray bursts (GRBs) and broad-lined Type Ic SNe makes a broader discussion of stripped-envelope SNe and their environments particularly relevant. If the SN progenitor itself cannot be directly identified, it is possible that examination of its immediate environment can provide some insight into the nature of the progenitor. It is also possible that revisiting the SN site sufficiently late enough after explosion could reveal the presence of a binary companion. I will present high-spatial-resolution observations obtained with the Hubble Space Telescope of the sites and environments of stripped-envelope supernovae, and I will discuss the implications of the resulting analysis. I will include here, e.g., the environments of the recent SN 2011dh, SN 2012au, SN 2013df, SN 2013dk, and iPTF13bvn. Support was provided by NASA through a grant from STScI, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  7. Spatially Resolved Atomic and Molecular Spectroscopy in Microelectronics Processing Plasmas

    SciTech Connect

    Hebner, G.A.

    1998-10-14

    Plasma processing of microelectronic materials is strongly dependent on the generation and control of neutral radial and ion species generated in a plasma. For example, process uniformity across a #er is drken by a combination of plasma charged particle and neutral uniformity. Due to extensive rexarch and engineering the current generation of commercial plasma reactors can generate very radially uniform ion distributions, usually better than ~ 2 perwnt as determined by ion saturation measurements. Due in part to the difficulty associated with determining the neutral radial distributions, control of the neutral radical uniformity is less well developed. This abstract will review our recent measurements of the spatial distribution of severaI important atomic and molecukw species in inductively coupled plasmas through C12 / BCIJ / Ar containing gas mixtures. Measured species include the ground state Cl and BC1 densities as well as the metastable argon density. The fbeus of this review will be on the experimental techniques and results. In addition to assisting in the development of a fbndarnental understanding of the important pkunna physics, these measurements have been used to benchmark multi dimensional plasma discharge codes.

  8. Determining Disease Intervention Strategies Using Spatially Resolved Simulations

    PubMed Central

    Read, Mark; Andrews, Paul S.; Timmis, Jon; Williams, Richard A.; Greaves, Richard B.; Sheng, Huiming; Coles, Mark; Kumar, Vipin

    2013-01-01

    Predicting efficacy and optimal drug delivery strategies for small molecule and biological therapeutics is challenging due to the complex interactions between diverse cell types in different tissues that determine disease outcome. Here we present a new methodology to simulate inflammatory disease manifestation and test potential intervention strategies in silico using agent-based computational models. Simulations created using this methodology have explicit spatial and temporal representations, and capture the heterogeneous and stochastic cellular behaviours that lead to emergence of pathology or disease resolution. To demonstrate this methodology we have simulated the prototypic murine T cell-mediated autoimmune disease experimental autoimmune encephalomyelitis, a mouse model of multiple sclerosis. In the simulation immune cell dynamics, neuronal damage and tissue specific pathology emerge, closely resembling behaviour found in the murine model. Using the calibrated simulation we have analysed how changes in the timing and efficacy of T cell receptor signalling inhibition leads to either disease exacerbation or resolution. The technology described is a powerful new method to understand cellular behaviours in complex inflammatory disease, permits rational design of drug interventional strategies and has provided new insights into the role of TCR signalling in autoimmune disease progression. PMID:24244694

  9. Toward reliable retrieval of functional information of papillary dermis using spatially resolved diffuse reflectance spectroscopy.

    PubMed

    Chen, Yu-Wen; Guo, Jun-Yen; Tzeng, Shih-Yu; Chou, Ting-Chun; Lin, Ming-Jen; Huang, Lynn Ling-Huei; Yang, Chao-Chun; Hsu, Chao-Kai; Tseng, Sheng-Hao

    2016-02-01

    Spatially resolved diffuse reflectance spectroscopy (SRDRS) has been employed to quantify tissue optical properties and its interrogation volume is majorly controlled by the source-to-detector separations (SDSs). To noninvasively quantify properties of dermis, a SRDRS setup that includes SDS shorter than 1 mm is required. It will be demonstrated in this study that Monte Carlo simulations employing the Henyey-Greenstein phase function cannot always precisely predict experimentally measured diffuse reflectance at such short SDSs, and we speculated this could be caused by the non-negligible backward light scattering at short SDSs that cannot be properly modeled by the Henyey-Greenstein phase function. To accurately recover the optical properties and functional information of dermis using SRDRS, we proposed the use of the modified two-layer (MTL) geometry. Monte Carlo simulations and phantom experiment results revealed that the MTL probing geometry was capable of faithfully recovering the optical properties of upper dermis. The capability of the MTL geometry in probing the upper dermis properties was further verified through a swine study, and it was found that the measurement results were reasonably linked to histological findings. Finally, the MTL probe was utilized to study psoriatic lesions. Our results showed that the MTL probe was sensitive to the physiological condition of tissue volumes within the papillary dermis and could be used in studying the physiology of psoriasis. PMID:26977361

  10. Toward reliable retrieval of functional information of papillary dermis using spatially resolved diffuse reflectance spectroscopy

    PubMed Central

    Chen, Yu-Wen; Guo, Jun-Yen; Tzeng, Shih-Yu; Chou, Ting-Chun; Lin, Ming-Jen; Huang, Lynn Ling-Huei; Yang, Chao-Chun; Hsu, Chao-Kai; Tseng, Sheng-Hao

    2016-01-01

    Spatially resolved diffuse reflectance spectroscopy (SRDRS) has been employed to quantify tissue optical properties and its interrogation volume is majorly controlled by the source-to-detector separations (SDSs). To noninvasively quantify properties of dermis, a SRDRS setup that includes SDS shorter than 1 mm is required. It will be demonstrated in this study that Monte Carlo simulations employing the Henyey-Greenstein phase function cannot always precisely predict experimentally measured diffuse reflectance at such short SDSs, and we speculated this could be caused by the non-negligible backward light scattering at short SDSs that cannot be properly modeled by the Henyey-Greenstein phase function. To accurately recover the optical properties and functional information of dermis using SRDRS, we proposed the use of the modified two-layer (MTL) geometry. Monte Carlo simulations and phantom experiment results revealed that the MTL probing geometry was capable of faithfully recovering the optical properties of upper dermis. The capability of the MTL geometry in probing the upper dermis properties was further verified through a swine study, and it was found that the measurement results were reasonably linked to histological findings. Finally, the MTL probe was utilized to study psoriatic lesions. Our results showed that the MTL probe was sensitive to the physiological condition of tissue volumes within the papillary dermis and could be used in studying the physiology of psoriasis. PMID:26977361

  11. Spatially-resolved intracellular sensing of hydrogen peroxide in living cells

    PubMed Central

    Warren, Emilie A. K.; Netterfield, Tatiana S.; Sarkar, Saheli; Kemp, Melissa L.; Payne, Christine K.

    2015-01-01

    Understanding intracellular redox chemistry requires new tools for the site-specific visualization of intracellular oxidation. We have developed a spatially-resolved intracellular sensor of hydrogen peroxide, HyPer-Tau, for time-resolved imaging in live cells. This sensor consists of a hydrogen peroxide-sensing protein tethered to microtubules. We demonstrate the use of the HyPer-Tau sensor for three applications; dose-dependent response of human cells to exogenous hydrogen peroxide, a model immune response of mouse macrophages to stimulation by bacterial toxin, and a spatially-resolved response to localized delivery of hydrogen peroxide. These results demonstrate that HyPer-Tau can be used as an effective tool for tracking changes in spatially localized intracellular hydrogen peroxide and for future applications in redox signaling. PMID:26585385

  12. A multi-objective optimization approach accurately resolves protein domain architectures

    PubMed Central

    Bernardes, J.S.; Vieira, F.R.J.; Zaverucha, G.; Carbone, A.

    2016-01-01

    Motivation: Given a protein sequence and a number of potential domains matching it, what are the domain content and the most likely domain architecture for the sequence? This problem is of fundamental importance in protein annotation, constituting one of the main steps of all predictive annotation strategies. On the other hand, when potential domains are several and in conflict because of overlapping domain boundaries, finding a solution for the problem might become difficult. An accurate prediction of the domain architecture of a multi-domain protein provides important information for function prediction, comparative genomics and molecular evolution. Results: We developed DAMA (Domain Annotation by a Multi-objective Approach), a novel approach that identifies architectures through a multi-objective optimization algorithm combining scores of domain matches, previously observed multi-domain co-occurrence and domain overlapping. DAMA has been validated on a known benchmark dataset based on CATH structural domain assignments and on the set of Plasmodium falciparum proteins. When compared with existing tools on both datasets, it outperforms all of them. Availability and implementation: DAMA software is implemented in C++ and the source code can be found at http://www.lcqb.upmc.fr/DAMA. Contact: juliana.silva_bernardes@upmc.fr or alessandra.carbone@lip6.fr Supplementary information: Supplementary data are available at Bioinformatics online. PMID:26458889

  13. NMR methods for in-situ biofilm metabolism studies: spatial and temporal resolved measurements

    SciTech Connect

    Majors, Paul D.; Mclean, Jeffrey S.; Fredrickson, Jim K.; Wind, Robert A.

    2005-11-01

    We are developing nuclear magnetic resonance (NMR) microscopy, spectroscopy and combined NMR/optical techniques to the study of biofilms. Objectives include: time and depth-resolved metabolite concentrations with isotropic spatial resolution on the order of 10 microns, metabolic pathways and flux rates, mass transport and ultimately their correlation with gene expression by optical microscopy in biofilms. These methods are being developed with Shewanella oneidensis MR-1 as a model system, but are equally applicable to other biofilm systems of interest. Thus, spatially resolved NMR of biofilms is expected to contribute significantly to the understanding of adherent cell metabolism.

  14. Accurate, multi-kb reads resolve complex populations and detect rare microorganisms

    PubMed Central

    Sharon, Itai; Kertesz, Michael; Hug, Laura A.; Pushkarev, Dmitry; Blauwkamp, Timothy A.; Castelle, Cindy J.; Amirebrahimi, Mojgan; Thomas, Brian C.; Burstein, David; Tringe, Susannah G.; Williams, Kenneth H.

    2015-01-01

    Accurate evaluation of microbial communities is essential for understanding global biogeochemical processes and can guide bioremediation and medical treatments. Metagenomics is most commonly used to analyze microbial diversity and metabolic potential, but assemblies of the short reads generated by current sequencing platforms may fail to recover heterogeneous strain populations and rare organisms. Here we used short (150-bp) and long (multi-kb) synthetic reads to evaluate strain heterogeneity and study microorganisms at low abundance in complex microbial communities from terrestrial sediments. The long-read data revealed multiple (probably dozens of) closely related species and strains from previously undescribed Deltaproteobacteria and Aminicenantes (candidate phylum OP8). Notably, these are the most abundant organisms in the communities, yet short-read assemblies achieved only partial genome coverage, mostly in the form of short scaffolds (N50 = ∼2200 bp). Genome architecture and metabolic potential for these lineages were reconstructed using a new synteny-based method. Analysis of long-read data also revealed thousands of species whose abundances were <0.1% in all samples. Most of the organisms in this “long tail” of rare organisms belong to phyla that are also represented by abundant organisms. Genes encoding glycosyl hydrolases are significantly more abundant than expected in rare genomes, suggesting that rare species may augment the capability for carbon turnover and confer resilience to changing environmental conditions. Overall, the study showed that a diversity of closely related strains and rare organisms account for a major portion of the communities. These are probably common features of many microbial communities and can be effectively studied using a combination of long and short reads. PMID:25665577

  15. Spatially resolved mapping of disorder type and distribution in random systems using artificial neural network recognition

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Ovchinnikov, O.; Guo, S.; Griggio, F.; Jesse, S.; Trolier-McKinstry, S.; Kalinin, S. V.

    2011-07-01

    The spatial variability of the polarization dynamics in thin film ferroelectric capacitors was probed by recognition analysis of spatially resolved spectroscopic data. Switching spectroscopy piezoresponse force microscopy (SSPFM) was used to measure local hysteresis loops and map them on a two dimensional (2D) random-bond, random-field Ising model. A neural-network based recognition approach was utilized to analyze the hysteresis loops and their spatial variability. Strong variability is observed in the polarization dynamics around macroscopic cracks because of the modified local-elastic and electric-boundary conditions, with the most pronounced effect on the length scale of ˜100 nm away from the crack. The recognition approach developed here is universal and can potentially be applied for arbitrary macroscopic and spatially resolved data, including temperature- and field-dependent hysteresis, I-V curve mapping, electron microscopy electron energy loss spectroscopy (EELS) imaging, and many others.

  16. Performance of orbital neutron instruments for spatially resolved hydrogen measurements of airless planetary bodies.

    PubMed

    Lawrence, David J; Elphic, Richard C; Feldman, William C; Funsten, Herbert O; Prettyman, Thomas H

    2010-03-01

    Orbital neutron spectroscopy has become a standard technique for measuring planetary surface compositions from orbit. While this technique has led to important discoveries, such as the deposits of hydrogen at the Moon and Mars, a limitation is its poor spatial resolution. For omni-directional neutron sensors, spatial resolutions are 1-1.5 times the spacecraft's altitude above the planetary surface (or 40-600 km for typical orbital altitudes). Neutron sensors with enhanced spatial resolution have been proposed, and one with a collimated field of view is scheduled to fly on a mission to measure lunar polar hydrogen. No quantitative studies or analyses have been published that evaluate in detail the detection and sensitivity limits of spatially resolved neutron measurements. Here, we describe two complementary techniques for evaluating the hydrogen sensitivity of spatially resolved neutron sensors: an analytic, closed-form expression that has been validated with Lunar Prospector neutron data, and a three-dimensional modeling technique. The analytic technique, called the Spatially resolved Neutron Analytic Sensitivity Approximation (SNASA), provides a straightforward method to evaluate spatially resolved neutron data from existing instruments as well as to plan for future mission scenarios. We conclude that the existing detector--the Lunar Exploration Neutron Detector (LEND)--scheduled to launch on the Lunar Reconnaissance Orbiter will have hydrogen sensitivities that are over an order of magnitude poorer than previously estimated. We further conclude that a sensor with a geometric factor of approximately 100 cm(2) Sr (compared to the LEND geometric factor of approximately 10.9 cm(2) Sr) could make substantially improved measurements of the lunar polar hydrogen spatial distribution. PMID:20298147

  17. Performance of Orbital Neutron Instruments for Spatially Resolved Hydrogen Measurements of Airless Planetary Bodies

    PubMed Central

    Elphic, Richard C.; Feldman, William C.; Funsten, Herbert O.; Prettyman, Thomas H.

    2010-01-01

    Abstract Orbital neutron spectroscopy has become a standard technique for measuring planetary surface compositions from orbit. While this technique has led to important discoveries, such as the deposits of hydrogen at the Moon and Mars, a limitation is its poor spatial resolution. For omni-directional neutron sensors, spatial resolutions are 1–1.5 times the spacecraft's altitude above the planetary surface (or 40–600 km for typical orbital altitudes). Neutron sensors with enhanced spatial resolution have been proposed, and one with a collimated field of view is scheduled to fly on a mission to measure lunar polar hydrogen. No quantitative studies or analyses have been published that evaluate in detail the detection and sensitivity limits of spatially resolved neutron measurements. Here, we describe two complementary techniques for evaluating the hydrogen sensitivity of spatially resolved neutron sensors: an analytic, closed-form expression that has been validated with Lunar Prospector neutron data, and a three-dimensional modeling technique. The analytic technique, called the Spatially resolved Neutron Analytic Sensitivity Approximation (SNASA), provides a straightforward method to evaluate spatially resolved neutron data from existing instruments as well as to plan for future mission scenarios. We conclude that the existing detector—the Lunar Exploration Neutron Detector (LEND)—scheduled to launch on the Lunar Reconnaissance Orbiter will have hydrogen sensitivities that are over an order of magnitude poorer than previously estimated. We further conclude that a sensor with a geometric factor of ∼ 100 cm2 Sr (compared to the LEND geometric factor of ∼ 10.9 cm2 Sr) could make substantially improved measurements of the lunar polar hydrogen spatial distribution. Key Words: Planetary instrumentation—Planetary science—Moon—Spacecraft experiments—Hydrogen. Astrobiology 10, 183–200. PMID:20298147

  18. Peach maturity/quality assessment using hyperspectral imaging-based spatially-resolved technique

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to measure the absorption and reduced scattering coefficients of peaches, using a hyperspectral imaging-based spatially-resolved method, for their maturity/quality assessment. A newly developed optical property measuring instrument was used for acquiring hyperspect...

  19. Spatially-resolved spectroscopic technique for measuring optical properties of food

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantification of optical properties is important to understand light interaction with biological materials, and to develop effective optical sensing techniques for property characterization and quality measurement of food products. This chapter reviews spatially-resolved method, with the focus on f...

  20. Spatially Resolved Analysis of Amines Using a Fluorescence Molecular Probe: Molecular Analysis of IDPs

    NASA Technical Reports Server (NTRS)

    Clemett, S. J.; Messenger, S.; Thomas-Keprta, K. L.; Wentworth, S. J.; Robinson, G. A.; McKay, D. S.

    2002-01-01

    Some Interplanetary Dust Particles (IDPs) have large isotope anomalies in H and N. To address the nature of the carrier phase, we are developing a procedure to spatially resolve the distribution of organic species on IDP thin sections utilizing fluorescent molecular probes. Additional information is contained in the original extended abstract.

  1. Spectroscopic Technique for Measuring the Texture of Horticultural Products: Spatially Resolved Approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book chapter reviews the latest developments and applications of spatially resolved spectroscopic techniques for measuring the optical properties and texture or firmness of horticultural products. The chapter first provides a brief overview of the theory of light transfer in turbid biological m...

  2. Determining the Optical Properties of Two-Layer Turbid Materials Based on Spatially Resolved Diffuse Reflectance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral imaging-based spatially resolved technique is useful for determining the optical properties of fruits and food products that are homogeneous. To better characterize fruit properties and quality attributes, it is necessary to consider fruit to be composed of two homogeneous layers, i.e....

  3. Wakeful rest promotes the integration of spatial memories into accurate cognitive maps.

    PubMed

    Craig, Michael; Dewar, Michaela; Harris, Mathew A; Della Sala, Sergio; Wolbers, Thomas

    2016-02-01

    Flexible spatial navigation, e.g. the ability to take novel shortcuts, is contingent upon accurate mental representations of environments-cognitive maps. These cognitive maps critically depend on hippocampal place cells. In rodents, place cells replay recently travelled routes, especially during periods of behavioural inactivity (sleep/wakeful rest). This neural replay is hypothesised to promote not only the consolidation of specific experiences, but also their wider integration, e.g. into accurate cognitive maps. In humans, rest promotes the consolidation of specific experiences, but the effect of rest on the wider integration of memories remained unknown. In the present study, we examined the hypothesis that cognitive map formation is supported by rest-related integration of new spatial memories. We predicted that if wakeful rest supports cognitive map formation, then rest should enhance knowledge of overarching spatial relations that were never experienced directly during recent navigation. Forty young participants learned a route through a virtual environment before either resting wakefully or engaging in an unrelated perceptual task for 10 min. Participants in the wakeful rest condition performed more accurately in a delayed cognitive map test, requiring the pointing to landmarks from a range of locations. Importantly, the benefit of rest could not be explained by active rehearsal, but can be attributed to the promotion of consolidation-related activity. These findings (i) resonate with the demonstration of hippocampal replay in rodents, and (ii) provide the first evidence that wakeful rest can improve the integration of new spatial memories in humans, a function that has, hitherto, been associated with sleep. PMID:26235141

  4. Spatially Resolved Thermodynamics of the Partially Ionized Exciton Gas in GaAs.

    PubMed

    Bieker, S; Henn, T; Kiessling, T; Ossau, W; Molenkamp, L W

    2015-06-01

    We report on the observation of macroscopic free exciton photoluminescence (PL) rings that appear in spatially resolved PL images obtained on a high purity GaAs sample. We demonstrate that a spatial temperature gradient in the photocarrier system, which is due to nonresonant optical excitation, locally modifies the population balance between free excitons and the uncorrelated electron-hole plasma described by the Saha equation and accounts for the experimentally observed nontrivial PL profiles. The exciton ring formation is a particularly instructive manifestation of the spatially dependent thermodynamics of a partially ionized exciton gas in a bulk semiconductor. PMID:26196644

  5. Spatially Resolved Thermodynamics of the Partially Ionized Exciton Gas in GaAs

    NASA Astrophysics Data System (ADS)

    Bieker, S.; Henn, T.; Kiessling, T.; Ossau, W.; Molenkamp, L. W.

    2015-06-01

    We report on the observation of macroscopic free exciton photoluminescence (PL) rings that appear in spatially resolved PL images obtained on a high purity GaAs sample. We demonstrate that a spatial temperature gradient in the photocarrier system, which is due to nonresonant optical excitation, locally modifies the population balance between free excitons and the uncorrelated electron-hole plasma described by the Saha equation and accounts for the experimentally observed nontrivial PL profiles. The exciton ring formation is a particularly instructive manifestation of the spatially dependent thermodynamics of a partially ionized exciton gas in a bulk semiconductor.

  6. Spatially Resolved Mapping of Disorder Type and Distribution in Random Systems using Artificial Neural Network Recognition

    SciTech Connect

    Jesse, Stephen; Kalinin, Sergei V; Kumar, Amit; Ovchinnikov, Oleg S; Guo, Senli; Griggio, Flavio; Trolier-Mckinstry, Susan E

    2011-01-01

    The spatial variability of the polarization dynamics in thin film ferroelectric capacitors was probed by recognition analysis of spatially-resolved spectroscopic data. Switching spectroscopy piezoresponse force microscopy was used to measure local hysteresis loops and map them on a 2D random-bond, random-field Ising model. A neural-network based recognition approach was utilized to analyze the hysteresis loops and their spatial variability. Strong variability is observed in the polarization dynamics around macroscopic cracks due to the modified local elastic and electric boundary conditions, with most pronounced effect on the length scale of ~100 nm away from the crack.

  7. The first spatially resolved spectra of the beta Pic gas disk

    NASA Astrophysics Data System (ADS)

    Brandeker, A.

    2014-09-01

    beta Pictoris was known to be surrounded by gas long before the disk itself was discovered. The spatial distribution of the circumstellar gas, however, was largely unconstrained until emission from the gas was spatially resolved from the star, and could be directly mapped. A puzzling result was that neutral sodium was observed to orbit the star, since the stellar gravity for this element is irrelevant compared to the strong stellar radiation pressure. A possible solution was suggested when the gas disk was found to be much more carbon rich than would be expected from cosmic abundances: the carbon could act as a braking agent. But why, then, is the disk gas so carbon rich? In this short focus, I will describe how the first spatially resolved observations of circumstellar gas emission around beta Pic came about, what we learned from them, and what questions they generated.

  8. Geocoding large population-level administrative datasets at highly resolved spatial scales

    PubMed Central

    Edwards, Sharon E.; Strauss, Benjamin; Miranda, Marie Lynn

    2014-01-01

    Using geographic information systems to link administrative databases with demographic, social, and environmental data allows researchers to use spatial approaches to explore relationships between exposures and health. Traditionally, spatial analysis in public health has focused on the county, zip code, or tract level because of limitations to geocoding at highly resolved scales. Using 2005 birth and death data from North Carolina, we examine our ability to geocode population-level datasets at three spatial resolutions – zip code, street, and parcel. We achieve high geocoding rates at all three resolutions, with statewide street geocoding rates of 88.0% for births and 93.2% for deaths. We observe differences in geocoding rates across demographics and health outcomes, with lower geocoding rates in disadvantaged populations and the most dramatic differences occurring across the urban-rural spectrum. Our results suggest highly resolved spatial data architectures for population-level datasets are viable through geocoding individual street addresses. We recommend routinely geocoding administrative datasets to the highest spatial resolution feasible, allowing public health researchers to choose the spatial resolution used in analysis based on an understanding of the spatial dimensions of the health outcomes and exposures being investigated. Such research, however, must acknowledge how disparate geocoding success across subpopulations may affect findings. PMID:25383017

  9. Computational optimization of the configuration of a spatially resolved spectroscopy sensor for milk analysis.

    PubMed

    Watté, Rodrigo; Aernouts, Ben; Van Beers, Robbe; Postelmans, Annelies; Saeys, Wouter

    2016-04-21

    A global optimizer has been developed, capable of computing the optimal configuration in a probe for spatially resolved reflectance spectroscopy (SRS). The main objective is to minimize the number of detection fibers, while maintaining an accurate estimation of both absorption and scattering profiles. Multiple fibers are necessary to robustify the estimation of optical properties against noise, which is typically present in the measured signals and influences the accuracy of the inverse estimation. The optimizer is based on a robust metamodel-based inverse estimation of the absorption coefficient and a reduced scattering coefficient from the acquired SRS signals. A genetic algorithm is used to evaluate the effect of the fiber placement on the performance of the inverse estimator to find the bulk optical properties of raw milk. The algorithm to find the optimal fiber placement was repeatedly executed for cases with a different number of detection fibers, ranging from 3 to 30. Afterwards, the optimal designs for each considered number of fibers were compared based on their performance in separating the absorption and scattering properties, and the significance of the differences was tested. A sensor configuration with 13 detection fibers was found to be the combination with the lowest number of fibers which provided an estimation performance which was not significantly worse than the one obtained with the best design (30 detection fibers). This design resulted in the root mean squared error of prediction (RMSEP) of 1.411 cm(-1) (R(2) = 0.965) for the estimation of the bulk absorption coefficient values, and 0.382 cm(-1) (R(2) = 0.996) for the reduced scattering coefficient values. PMID:27026600

  10. Determining Chemically and Spatially Resolved Atomic Profile of Low Contrast Interface Structure with High Resolution

    PubMed Central

    Nayak, Maheswar; Pradhan, P. C.; Lodha, G. S.

    2015-01-01

    We present precise measurements of atomic distributions of low electron density contrast at a buried interface using soft x-ray resonant scattering. This approach allows one to construct chemically and spatially highly resolved atomic distribution profile upto several tens of nanometer in a non-destructive and quantitative manner. We demonstrate that the method is sensitive enough to resolve compositional differences of few atomic percent in nano-scaled layered structures of elements with poor electron density differences (0.05%). The present study near the edge of potential impurities in soft x-ray range for low-Z system will stimulate the activity in that field. PMID:25726866

  11. Determining chemically and spatially resolved atomic profile of low contrast interface structure with high resolution.

    PubMed

    Nayak, Maheswar; Pradhan, P C; Lodha, G S

    2015-01-01

    We present precise measurements of atomic distributions of low electron density contrast at a buried interface using soft x-ray resonant scattering. This approach allows one to construct chemically and spatially highly resolved atomic distribution profile upto several tens of nanometer in a non-destructive and quantitative manner. We demonstrate that the method is sensitive enough to resolve compositional differences of few atomic percent in nano-scaled layered structures of elements with poor electron density differences (0.05%). The present study near the edge of potential impurities in soft x-ray range for low-Z system will stimulate the activity in that field. PMID:25726866

  12. Role of density modulation in the spatially resolved dynamics of strongly confined liquids

    NASA Astrophysics Data System (ADS)

    Saw, Shibu; Dasgupta, Chandan

    2016-08-01

    Confinement by walls usually produces a strong modulation in the density of dense liquids near the walls. Using molecular dynamics simulations, we examine the effects of the density modulation on the spatially resolved dynamics of a liquid confined between two parallel walls, using a resolution of a fraction of the interparticle distance in the liquid. The local dynamics is quantified by the relaxation time associated with the temporal autocorrelation function of the local density. We find that this local relaxation time varies in phase with the density modulation. The amplitude of the spatial modulation of the relaxation time can be quite large, depending on the characteristics of the wall and thermodynamic parameters of the liquid. To disentangle the effects of confinement and density modulation on the spatially resolved dynamics, we compare the dynamics of a confined liquid with that of an unconfined one in which a similar density modulation is induced by an external potential. We find several differences indicating that density modulation alone cannot account for all the features seen in the spatially resolved dynamics of confined liquids. We also examine how the dynamics near a wall depends on the separation between the two walls and show that the features seen in our simulations persist in the limit of large wall separation.

  13. Role of density modulation in the spatially resolved dynamics of strongly confined liquids.

    PubMed

    Saw, Shibu; Dasgupta, Chandan

    2016-08-01

    Confinement by walls usually produces a strong modulation in the density of dense liquids near the walls. Using molecular dynamics simulations, we examine the effects of the density modulation on the spatially resolved dynamics of a liquid confined between two parallel walls, using a resolution of a fraction of the interparticle distance in the liquid. The local dynamics is quantified by the relaxation time associated with the temporal autocorrelation function of the local density. We find that this local relaxation time varies in phase with the density modulation. The amplitude of the spatial modulation of the relaxation time can be quite large, depending on the characteristics of the wall and thermodynamic parameters of the liquid. To disentangle the effects of confinement and density modulation on the spatially resolved dynamics, we compare the dynamics of a confined liquid with that of an unconfined one in which a similar density modulation is induced by an external potential. We find several differences indicating that density modulation alone cannot account for all the features seen in the spatially resolved dynamics of confined liquids. We also examine how the dynamics near a wall depends on the separation between the two walls and show that the features seen in our simulations persist in the limit of large wall separation. PMID:27497572

  14. Chromatic-free spatially resolved optical emission spectroscopy diagnostics for microplasma

    NASA Astrophysics Data System (ADS)

    Zhu, Li-Guo; Chen, Wen-Cong; Zhu, Xi-Ming; Pu, Yi-Kang; Li, Ze-Ren

    2009-02-01

    A chromatic-free spatially resolved diagnostic system for microplasma measurement is proposed and demonstrated, which consists of an optical chromatic-free microscope mirror system, an electron multiplying charge coupled device (EMCCD), and bandpass filters. The diagnostic system free of chromatic aberrations with a spatial resolution of about 6 μm is achieved. The factors that limit the resolution of this diagnostic system have been analyzed, which are optical diffraction, the pixel size of the EMCCD, and the thickness of the microplasma. In this paper, the optimal condition for achieving a maximum resolution power has been analyzed. With this diagnostic system, we revealed the spatial nonuniformity of a microwave atmospheric-pressure argon microplasma. Furthermore, the spatial distribution of the time-averaged effective electron temperature has been estimated from the intensity distributions of 750.4 and 415.8 nm emissions.

  15. Spatially resolved in operando neutron scattering studies on Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Senyshyn, A.; Mühlbauer, M. J.; Dolotko, O.; Hofmann, M.; Pirling, T.; Ehrenberg, H.

    2014-01-01

    Spatially-resolved neutron diffraction has been applied to probe the lithium distribution in radial direction of a commercial Li-ion cell of 18650-type. The spatial evolution of selected Bragg reflections for LiCoO2 (positive electrode, "cathode") and graphite and lithium intercalated graphite (negative electrode, "anode") was observed and evaluated by taking beam attenuation and cell geometry effects into account. No evidences for lithium inhomogeneities have been found for the investigated set of cells. Computed neutron tomography using a monochromatic neutron beam confirmed the homogeneous lithium distribution. The relevance of the monochromatic beam to neutron imaging studies of Li-ion cells is discussed.

  16. Dynamical Spatially Resolved Response Function of Finite 1-D Nano Plasmas

    NASA Astrophysics Data System (ADS)

    Raitza, Thomas; Reinholz, Heidi; Röpke, Gerd

    2011-03-01

    The dynamical response of one dimensional chains containing 55 till 309 atoms is investigated using a restricted molecular dynamics simulation scheme. The total momentum correlation function of an electron cloud shows resonances that are related to different collective excitation modes of the nano plasma. Spatially resolved cross correlation functions are calculated to deduce the spatial structure and strength of these resonance modes. The dependence of the corresponding resonance frequencies on temperature, density and chain size is investigated. The width of the resonances is analyzed in terms of a mode dependent collision frequency.

  17. Spatially resolved charge transport study in discotic liquid crystalline organic semiconductors

    NASA Astrophysics Data System (ADS)

    Paul, Sanjoy; Semyonov, Alexander; Dawson, Nathan J.; Singer, Kenneth D.; Twieg, Robert J.; Ellman, Brett

    Spatially resolved time-of-flight photogeneration and mobility have been measured on a discotic liquid crystalline organic semiconductor using scanning time-of-flight microscopy (STOFm). STOFm simultaneously obtains time-of-flight transients and polarized transmittance across the sample. Various shapes in time-of-flight transients were observed and extracted charge transport parameters such as photogeneration efficiency, mobility, and trapping show significant spatial variation. In some cases these can be linked to electrode surface inhomogeneities. Detailed measurement methodology, experimental results and challenges in their analysis will be discussed.

  18. Grazing incidence technique to obtain spatially resolved spectra from laser heated plasmas

    NASA Technical Reports Server (NTRS)

    Behring, W. E.; Underwood, J. H.; Brown, C. M.; Feldman, U.; Seely, John F.

    1988-01-01

    An experimental method is described in which a grazing incidence spectrograph is used to obtain spatially resolved spectra of laser heated plasmas in the 6-370-A region. In the experiment, small target spheres were irradiated by tightly focused laser beams. A tilted grazing incidence elliptical mirror placed 1.3 m from the target focuses the plasma radiation on the spectrograph slit at a distance of 0.7 m producing a useful degree of spatial resolution in the recorded spectral lines. The spectrum from a copper target is presented together with an X-ray pinhole camera image of the plasma.

  19. Explicit off-line criteria for stable accurate time filtering of strongly unstable spatially extended systems.

    PubMed

    Majda, Andrew J; Grote, Marcus J

    2007-01-23

    Many contemporary problems in science involve making predictions based on partial observation of extremely complicated spatially extended systems with many degrees of freedom and physical instabilities on both large and small scales. Various new ensemble filtering strategies have been developed recently for these applications, and new mathematical issues arise. Here, explicit off-line test criteria for stable accurate discrete filtering are developed for use in the above context and mimic the classical stability analysis for finite difference schemes. First, constant coefficient partial differential equations, which are randomly forced and damped to mimic mesh scale energy spectra in the above problems are developed as off-line filtering test problems. Then mathematical analysis is used to show that under natural suitable hypothesis the time filtering algorithms for general finite difference discrete approximations to an sxs partial differential equation system with suitable observations decompose into much simpler independent s-dimensional filtering problems for each spatial wave number separately; in other test problems, such block diagonal models rigorously provide upper and lower bounds on the filtering algorithm. In this fashion, elementary off-line filtering criteria can be developed for complex spatially extended systems. The theory is illustrated for time filters by using both unstable and implicit difference scheme approximations to the stochastically forced heat equation where the combined effects of filter stability and model error are analyzed through the simpler off-line criteria. PMID:17227864

  20. Natural gas leaks detection by spatial-resolvable-CW-laser-based remote monitoring

    SciTech Connect

    Agishev, R.R.; Bajazitov, R.A.; Galeyev, M.M.; Ismagilow, Z.B.

    1996-12-31

    The opportunities of spatial-resolvable atmosphere monitoring and atmospheric pollutions remote chemical analysis based on the CW-laser radiants are investigated. A frequency-responsive processing peculiarities of atmosphere remote sensing signals are described. Application of the mentioned approach for the limited hydrocarbons remote detection and sensing is discussed. The requirements to the CW-LIDAR receiving and radiating systems parameters are formulated. The evaluations of the system sensitivity limit, measurement accuracy and accuracy increase ways are presented.

  1. Spatially resolving unconventional interface Landau quantization in a graphene monolayer-bilayer planar junction

    NASA Astrophysics Data System (ADS)

    Yan, Wei; Li, Si-Yu; Yin, Long-Jing; Qiao, Jia-Bin; Nie, Jia-Cai; He, Lin

    2016-05-01

    Hybrid quantum Hall (QH) junctions have been extensively studied by transport measurements due to their exciting physics and device applications. Here we report on spatially resolving electronic properties of such a junction on the nanoscale. We present a subnanometer-resolved scanning tunneling microscopy (STM) and scanning tunneling spectroscopy study of a monolayer-bilayer graphene planar junction in the QH regime. The atomically well-defined interface of such a junction allows us to spatially resolve the interface electronic properties. Around the interface, we detect Landau quantization of massless Dirac fermions as expected in the graphene monolayer for filled states of the junction, whereas unexpectedly, only Landau quantization of massive Dirac fermions as expected in the graphene bilayer is observed for empty states. The observed unconventional interface Landau quantization arises from the fact that the quantum conductance across the interface is solely determined by the minimum filling factors (number of edge modes) in the graphene monolayer and bilayer regions of the junction. Our finding opens the way to spatially explore the QH effect of different graphene hybrid structures only using a STM.

  2. Probing the limitations of Sigmund's model of spatially resolved sputtering using Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Hobler, Gerhard; Bradley, R. Mark; Urbassek, Herbert M.

    2016-05-01

    Sigmund's model of spatially resolved sputtering is the underpinning of many models of nanoscale pattern formation induced by ion bombardment. It is based on three assumptions: (i) the number of sputtered atoms is proportional to the nuclear energy deposition (NED) near the surface, (ii) the NED distribution is independent of the orientation and shape of the solid surface and is identical to the one in an infinite medium, and (iii) the NED distribution in an infinite medium can be approximated by a Gaussian. We test the validity of these assumptions using Monte Carlo simulations of He, Ar, and Xe impacts on Si at energies of 2, 20, and 200 keV with incidence angles from perpendicular to grazing. We find that for the more commonly-employed beam parameters (Ar and Xe ions at 2 and 20 keV and nongrazing incidence), the Sigmund model's predictions are within a factor of 2 of the Monte Carlo results for the total sputter yield and the first two moments of the spatially resolved sputter yield. This is partly due to a compensation of errors introduced by assumptions (i) and (ii). The Sigmund model, however, does not describe the skewness of the spatially resolved sputter yield, which is almost always significant. The approximation is much poorer for He ions and/or high energies (200 keV). All three of Sigmund's assumptions break down at grazing incidence angles. In all cases, we discuss the origin of the deviations from Sigmund's model.

  3. Communication: Vibrationally resolved photoelectron spectroscopy of the tetracyanoquinodimethane (TCNQ) anion and accurate determination of the electron affinity of TCNQ

    NASA Astrophysics Data System (ADS)

    Zhu, Guo-Zhu; Wang, Lai-Sheng

    2015-12-01

    Tetracyanoquinodimethane (TCNQ) is widely used as an electron acceptor to form highly conducting organic charge-transfer solids. Surprisingly, the electron affinity (EA) of TCNQ is not well known and has never been directly measured. Here, we report vibrationally resolved photoelectron spectroscopy (PES) of the TCNQ- anion produced using electrospray and cooled in a cryogenic ion trap. Photoelectron spectrum taken at 354.7 nm represents the detachment transition from the ground state of TCNQ- to that of neutral TCNQ with a short vibrational progression. The EA of TCNQ is measured accurately to be 3.383 ± 0.001 eV (27 289 ± 8 cm-1), compared to the 2.8 ± 0.1 eV value known in the literature and measured previously using collisional ionization technique. In addition, six vibrational peaks are observed in the photoelectron spectrum, yielding vibrational frequencies for three totally symmetric modes of TCNQ. Two-photon PES via a bound electronic excited state of TCNQ- at 3.100 eV yields a broad low kinetic energy peak due to fast internal conversion to vibrationally excited levels of the anion ground electronic state. The high EA measured for TCNQ underlies its ability as a good electron acceptor.

  4. Communication: Vibrationally resolved photoelectron spectroscopy of the tetracyanoquinodimethane (TCNQ) anion and accurate determination of the electron affinity of TCNQ

    SciTech Connect

    Zhu, Guo-Zhu; Wang, Lai-Sheng

    2015-12-14

    Tetracyanoquinodimethane (TCNQ) is widely used as an electron acceptor to form highly conducting organic charge-transfer solids. Surprisingly, the electron affinity (EA) of TCNQ is not well known and has never been directly measured. Here, we report vibrationally resolved photoelectron spectroscopy (PES) of the TCNQ{sup −} anion produced using electrospray and cooled in a cryogenic ion trap. Photoelectron spectrum taken at 354.7 nm represents the detachment transition from the ground state of TCNQ{sup −} to that of neutral TCNQ with a short vibrational progression. The EA of TCNQ is measured accurately to be 3.383 ± 0.001 eV (27 289 ± 8 cm{sup −1}), compared to the 2.8 ± 0.1 eV value known in the literature and measured previously using collisional ionization technique. In addition, six vibrational peaks are observed in the photoelectron spectrum, yielding vibrational frequencies for three totally symmetric modes of TCNQ. Two-photon PES via a bound electronic excited state of TCNQ{sup −} at 3.100 eV yields a broad low kinetic energy peak due to fast internal conversion to vibrationally excited levels of the anion ground electronic state. The high EA measured for TCNQ underlies its ability as a good electron acceptor.

  5. Time-resolved and spatially-resolved infrared spectroscopic observation of seeded nucleation controlling geopolymer gel formation.

    PubMed

    Hajimohammadi, Ailar; Provis, John L; van Deventer, Jannie S J

    2011-05-15

    The effect of seeded nucleation on the formation and structural evolution of one-part ("just add water") geopolymer gels is investigated. Gel-forming systems are seeded with each of three different oxide nanoparticles, and seeding is shown to have an important role in controlling the silica release rate from the solid geothermal silica precursor, and in the development of physical properties of the gels. Nucleation accelerates the chemical changes taking place during geopolymer formation. The nature of the seeds affects the structure of the growing gel by affecting the extent of phase separation, identified by the presence of a distinct silica-rich gel in addition to the main, more alumina-rich gel phase. Synchrotron radiation-based infrared microscopy (SR-FTIR) shows the effect of nucleation on the heterogeneous nanostructure and microstructure of geopolymer gels, and is combined with data obtained by time-resolved FTIR analysis to provide a more holistic view of the reaction processes at a level of detail that has not previously been available. While spatially averaged (ATR-FTIR) infrared results show similar spectra for seeded and unseeded samples which have been cured for more than 3 weeks, SR-FTIR results show marked differences in gel structure as a result of seeding. PMID:21397245

  6. Spatially-resolved x-ray scattering measurements of a planar blast wave

    NASA Astrophysics Data System (ADS)

    Gamboa, E. J.; Montgomery, D. S.; Benage, J. F.; Falk, K.; Kuranz, C. C.; Keiter, P. A.; Drake, R. P.

    2012-10-01

    In many laboratory astrophysics experiments, intense laser irradiation creates novel material conditions with large, one-dimensional gradients in the temperature, density, and ionization state. X-ray Thomson scattering is a powerful technique for measuring these plasma parameters. However, the scattered signal is typically measured with little or no spatial resolution, which limits the ability to diagnose inhomogeneous plasmas. We report on the development of a new imaging x-ray Thomson spectrometer (IXTS) for the Omega laser facility. The diffraction of x-rays from a toroidally curved crystal creates high-resolution images that are spatially resolved along a one-dimensional profile while spectrally dispersing the radiation. An experiment is described in which we used the IXTS to measure the spatial temperature profile of a novel system. A low-density carbon foam was irradiated with intensities on the order of 10^15 W/cm^2, launching a planar blast wave. After a delay of several nanoseconds, x-rays created from irradiation of a nickel foil, scattered at 90 and were recorded by the IXTS. The resulting spatially resolved scattering spectra were analyzed to extract the temperature profile across the blast wave.

  7. Spatially resolved spectroscopy analysis of the XMM-Newton large program on SN1006

    NASA Astrophysics Data System (ADS)

    Li, Jiang-Tao; Decourchelle, Anne; Miceli, Marco; Vink, Jacco; Bocchino, Fabrizio

    2016-04-01

    We perform analysis of the XMM-Newton large program on SN1006 based on our newly developed methods of spatially resolved spectroscopy analysis. We extract spectra from low and high resolution meshes. The former (3596 meshes) is used to roughly decompose the thermal and non-thermal components and characterize the spatial distributions of different parameters, such as temperature, abundances of different elements, ionization age, and electron density of the thermal component, as well as photon index and cutoff frequency of the non-thermal component. On the other hand, the low resolution meshes (583 meshes) focus on the interior region dominated by the thermal emission and have enough counts to well characterize the Si lines. We fit the spectra from the low resolution meshes with different models, in order to decompose the multiple plasma components at different thermal and ionization states and compare their spatial distributions. In this poster, we will present the initial results of this project.

  8. Spatially resolved measurement of high doses in microbeam radiation therapy using samarium doped fluorophosphate glasses

    SciTech Connect

    Okada, Go; Morrell, Brian; Koughia, Cyril; Kasap, Safa; Edgar, Andy; Varoy, Chris; Belev, George; Wysokinski, Tomasz; Chapman, Dean

    2011-09-19

    The measurement of spatially resolved high doses in microbeam radiation therapy has always been a challenging task, where a combination of high dose response and high spatial resolution (microns) is required for synchrotron radiation peaked around 50 keV. The x-ray induced Sm{sup 3+}{yields} Sm{sup 2+} valence conversion in Sm{sup 3+} doped fluorophosphates glasses has been tested for use in x-ray dosimetry for microbeam radiation therapy. The conversion efficiency depends almost linearly on the dose of irradiation up to {approx}5 Gy and saturates at doses exceeding {approx}80 Gy. The conversion shows strong correlation with x-ray induced absorbance of the glass which is related to the formation of phosphorus-oxygen hole centers. When irradiated through a microslit collimator, a good spatial resolution and high ''peak-to-valley'' contrast have been observed by means of confocal photoluminescence microscopy.

  9. Development of a Spatially Resolved ^3He Quasi-Particle Detector

    NASA Astrophysics Data System (ADS)

    Barquist, C. S.; Zheng, P.; Jiang, W. G.; Lee, Y.; Yoon, Y. K.; Schumann, T.; Nogan, J.; Lilly, M.

    2016-05-01

    Andreev surface bound sates are known to exist on the boundaries of superfluid ^3He-B. However, the detailed nature of their interaction with bulk quasi-particles is not well known. In a manner similar to angle-resolved photo-emission spectroscopy, surface states can be probed by measuring the change in momentum of bulk quasi-particles scattered from the surface. In order to make such a measurement, we have designed a spatially resolved quasi-particle detector. The detector consists of an array of micro-machined resonators, which are sensitive to quasi-particle flux. The detector is based on previously developed micro-machined resonators, which have been successfully used to study superfluid ^3He-B and ^4He. Presented here is the design of the detector and the fabrication procedure.

  10. Spatially Resolved Thermal Analysis of High Power LEDs Using Thermoreflectance Microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Hexuan; Al-Hemyari, Kadhair; Yan, Susu; Summers, Joseph; Hudgings, Janice

    2012-02-01

    The efficiency, reliability, and lifetime of high power light emitting diodes (LEDs) depend critically on their operating temperature. The lateral temperature distribution is of particular importance with large area, high power LEDs as defects related to overheating in high power LEDs usually occur at a high rate at the surface. In this work, we present the use of lock-in thermoreflectance imaging to measure the spatially resolved surface thermal distribution of operating LEDs. This non-invasive thermography technique offers high spatial and thermal resolutions. We show that results of thermoreflectance surface temperature are quantitatively consistent with temperature measurements obtained using forward voltage bias and wavelength shift techniques. We demonstrate the power of spatially resolved thermoreflectance by imaging the highly non-uniform surface temperature distribution of an operating LED at high electrical bias power. We conclude that the non-uniform surface temperature distribution is resulted from non-uniformly distributed inject current and overheating at the contacts. We also investigate the thermal impact of encapsulating commercial LEDs with a plastic lens and silicone epoxy.

  11. Test Sample for the Spatially Resolved Quantification of Illicit Drugs on Fingerprints Using Imaging Mass Spectrometry.

    PubMed

    Muramoto, Shin; Forbes, Thomas P; van Asten, Arian C; Gillen, Greg

    2015-01-01

    A novel test sample for the spatially resolved quantification of illicit drugs on the surface of a fingerprint using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and desorption electrospray ionization mass spectrometry (DESI-MS) was demonstrated. Calibration curves relating the signal intensity to the amount of drug deposited on the surface were generated from inkjet-printed arrays of cocaine, methamphetamine, and heroin with a deposited-mass ranging nominally from 10 pg to 50 ng per spot. These curves were used to construct concentration maps that visualized the spatial distribution of the drugs on top of a fingerprint, as well as being able to quantify the amount of drugs in a given area within the map. For the drugs on the fingerprint on silicon, ToF-SIMS showed great success, as it was able to generate concentration maps of all three drugs. On the fingerprint on paper, only the concentration map of cocaine could be constructed using ToF-SIMS and DESI-MS, as the signals of methamphetamine and heroin were completely suppressed by matrix and substrate effects. Spatially resolved quantification of illicit drugs using imaging mass spectrometry is possible, but the choice of substrates could significantly affect the results. PMID:25915085

  12. Spatially resolved high resolution x-ray spectroscopy for magnetically confined fusion plasmas (invited)

    SciTech Connect

    Ince-Cushman, A.; Rice, J. E.; Reinke, M. L.; Podpaly, Y.; Marmar, E. S.; Bitter, M.; Hill, K. W.; Scott, S.; Gu, M. F.; Eikenberry, E.; Broennimann, Ch.; Lee, S. G.

    2008-10-15

    The use of high resolution x-ray crystal spectrometers to diagnose fusion plasmas has been limited by the poor spatial localization associated with chord integrated measurements. Taking advantage of a new x-ray imaging spectrometer concept [M. Bitter et al., Rev. Sci. Instrum. 75, 3660 (2004)], and improvements in x-ray detector technology [Ch. Broennimann et al., J. Synchrotron Radiat. 13, 120 (2006)], a spatially resolving high resolution x-ray spectrometer has been built and installed on the Alcator C-Mod tokamak. This instrument utilizes a spherically bent quartz crystal and a set of two dimensional x-ray detectors arranged in the Johann configuration [H. H. Johann, Z. Phys. 69, 185 (1931)] to image the entire plasma cross section with a spatial resolution of about 1 cm. The spectrometer was designed to measure line emission from H-like and He-like argon in the wavelength range 3.7 and 4.0 A with a resolving power of approximately 10 000 at frame rates up to 200 Hz. Using spectral tomographic techniques [I. Condrea, Phys. Plasmas 11, 2427 (2004)] the line integrated spectra can be inverted to infer profiles of impurity emissivity, velocity, and temperature. From these quantities it is then possible to calculate impurity density and electron temperature profiles. An overview of the instrument, analysis techniques, and example profiles are presented.

  13. SPATIALLY RESOLVED SPECTROSCOPY OF SDSS J0952+2552: A CONFIRMED DUAL ACTIVE GALACTIC NUCLEUS

    SciTech Connect

    McGurk, R. C.; Max, C. E.; Rosario, D. J.; Shields, G. A.; Smith, K. L.; Wright, S. A. E-mail: max@ucolick.org E-mail: shieldsga@mail.utexas.edu E-mail: saw@astro.berkeley.edu

    2011-09-01

    Most massive galaxies contain supermassive black holes (SMBHs) in their cores. When galaxies merge, gas is driven to nuclear regions and can accrete onto the central black hole. Thus, one expects to see dual active galactic nuclei (AGNs) in a fraction of galaxy mergers. Candidates for galaxies containing dual AGNs have been identified by the presence of double-peaked narrow [O III] emission lines and by high spatial resolution images of close galaxy pairs. Spatially resolved spectroscopy is needed to confirm these galaxy pairs as systems with spatially separated double SMBHs. With the Keck 2 Laser Guide Star Adaptive Optics system and the OH Suppressing InfraRed Imaging Spectrograph near-infrared integral field spectrograph, we obtained spatially resolved spectra for SDSS J09527.62+255257.2, a radio-quiet quasar shown by previous imaging to consist of a galaxy and its close (1.''0) companion. We find that the main galaxy is a Type 1 AGN with both broad and narrow AGN emission lines in its spectrum, while the companion galaxy is a Type 2 AGN with narrow emission lines only. The two AGNs are separated by 4.8 kpc, and their redshifts correspond to those of the double peaks of the [O III] emission line seen in the Sloan Digital Sky Survey spectrum. Line diagnostics indicate that both components of the double emission lines are due to AGN photoionization. These results confirm that J0952+2552 contains two spatially separated AGNs. As one of the few confirmed dual AGNs at an intermediate separation of <10 kpc, this system offers a unique opportunity to study galaxy mergers and their effect on black hole growth.

  14. Community 15N isoscapes to resolve plant-plant-interactions at the spatial scale

    NASA Astrophysics Data System (ADS)

    Hellmann, Christine; Rascher, Katherine G.; Máguas, Cristina; Werner, Christiane

    2014-05-01

    Isoscapes have greatly improved our ability to understand biogeochemical processes on continental to global scales. However, the isoscapes framework may also have significant potential to resolve the spatial component of within-community interactions. For example, exotic plant invaders often exert strong impacts on ecosystem functioning, particularly regarding water-, carbon- and nutrient-cycles, but the spatial extent of such alterations is largely unknown. Here we show that massive N input by the N2-fixing exotic invasive Acacia longifolia to a Portuguese dune system can be traced using spatially resolved information on native plants' leaf δ15N. We found isotopic signatures of N to differ strongly between the native system (δ15N c. -10 o) and the atmospherically derived N in A. longifolia phyllodes (δ15N c. 0 o). Thus, sources of N for native plants could be readily distinguished. Leaf δ15N of a native, non-fixing species was increasingly enriched the closer the plant grew to the invader, indicating uptake of fixed N provided by A. longifolia. The enrichment was evident far beyond the stands of the invader, demonstrating that A. longifolia affected N budgets of native species up to a distance of 8 m exceeding the margin of the canopy. Furthermore, using the isoscapes approach, we were able to quantify the total area of N enrichment and could thus show that the area affected by invasion was at least 3.5 times larger than the area actually occupied by the invader. However, a native N2-fixing species had no such effects. Thus, downscaling isoscapes to the community level opens new frontiers in quantifying the spatial dimension of functional changes associated with plant invasions. Moreover, considering the feasibility and applicability of this approach, it may provide a promising tool to identify, quantify and monitor different types of functional plant-plant interactions within communities at a spatially explicit scale.

  15. Based on time and spatial-resolved SERS mapping strategies for detection of pesticides.

    PubMed

    Ma, Bingbing; Li, Pan; Yang, Liangbao; Liu, Jinhuai

    2015-08-15

    For the sensitive and convenient detection of pesticides, several sensing methods and materials have been widely explored. However, it is still a challenge to obtain sensitive, simple detection techniques for pesticides. Here, the simple and sensitive Time-resolved SERS mapping (T-SERS) and Spatial-resolved SERS mapping (S-SERS) are presented for detection of pesticides by using Au@Ag NPs as SERS substrate. The Time-resolved SERS mapping (T-SERS) is based on state translation nanoparticles from the wet state to the dry state to realize SERS measurements. During the SERS measurement, adhesive force drives the particles closer together and then average interparticle gap becomes smaller. Following, air then begins to intersperse into the liquid network and the particles are held together by adhesive forces at the solid-liquid-air interface. In the late stage of water evaporation, all particles are uniformly distributed. Thus, so called hotspots matrix that can hold hotspots between every two adjacent particles in efficient space with minimal polydispersity of particle size are achieved, accompanying the red-shift of surface plasmon peak and appearance of an optimal SPR resonated sharply with excitation wavelength. Here, we found that the T-SERS method exhibits the detection limits of 1-2 orders of magnitude higher than that of S-SERS. On the other hand, the T-SERS is very simple method with high detection sensitivity, better reproducibility (RSD=10.8%) and is beneficial to construction of a calibration curve in comparison with that of Spatial-resolved SERS mapping (S-SERS). Most importantly, as a result of its remarkable sensitivity, T-SERS mapping strategies have been applied to detection of several pesticides and the detect limit can down to 1nM for paraoxon, 0.5nM for sumithion. In short, T-SERS mapping measurement promises to open a market for SERS practical detection with prominent advantages. PMID:25966372

  16. Spatially resolved D-T(2) correlation NMR of porous media.

    PubMed

    Zhang, Yan; Blümich, Bernhard

    2014-05-01

    Within the past decade, 2D Laplace nuclear magnetic resonance (NMR) has been developed to analyze pore geometry and diffusion of fluids in porous media on the micrometer scale. Many objects like rocks and concrete are heterogeneous on the macroscopic scale, and an integral analysis of microscopic properties provides volume-averaged information. Magnetic resonance imaging (MRI) resolves this spatial average on the contrast scale set by the particular MRI technique. Desirable contrast parameters for studies of fluid transport in porous media derive from the pore-size distribution and the pore connectivity. These microscopic parameters are accessed by 1D and 2D Laplace NMR techniques. It is therefore desirable to combine MRI and 2D Laplace NMR to image functional information on fluid transport in porous media. Because 2D Laplace resolved MRI demands excessive measuring time, this study investigates the possibility to restrict the 2D Laplace analysis to the sum signals from low-resolution pixels, which correspond to pixels of similar amplitude in high-resolution images. In this exploratory study spatially resolved D-T2 correlation maps from glass beads and mortar are analyzed. Regions of similar contrast are first identified in high-resolution images to locate corresponding pixels in low-resolution images generated with D-T2 resolved MRI for subsequent pixel summation to improve the signal-to-noise ratio of contrast-specific D-T2 maps. This method is expected to contribute valuable information on correlated sample heterogeneity from the macroscopic and the microscopic scales in various types of porous materials including building materials and rock. PMID:24607821

  17. Spatially Resolved Spectra of the "Teacup" Active Galactic Nucleus: Tracing the History of a Dying Quasar

    NASA Astrophysics Data System (ADS)

    Gagne, J. P.; Crenshaw, D. M.; Kraemer, S. B.; Schmitt, H. R.; Keel, W. C.; Rafter, S.; Fischer, T. C.; Bennert, V. N.; Schawinski, K.

    2014-09-01

    The Sloan Digital Sky Survey (SDSS) Galaxy Zoo project has revealed a number of spectacular galaxies possessing extended emission-line regions (EELRs), the most famous being Hanny's Voorwerp galaxy. We present another EELR object discovered in the SDSS endeavor: the Teacup active galactic nucleus (AGN). Nicknamed for its EELR, which has a "handle"-like structure protruding 15 kpc into the northeast quadrant of the galaxy. We analyze the physical conditions of this galaxy with long-slit, ground-based spectroscopy from the Lowell, Lick, and KPNO observatories. With the Lowell 1.8 m Perkin's telescope we took multiple observations at different offset positions, allowing us to recover spatially resolved spectra across the galaxy. Line diagnostics indicate the ionized gas is photoionized primarily by the AGN. Additionally we are able to derive the hydrogen density from the [S II] λ6716/λ6731 ratio. We generated two-component photoionization models for each spatially resolved Lowell spectrum. These models allow us to calculate the AGN bolometric luminosity seen by the gas at different radii from the nuclear center of the Teacup. Our results show a drop in bolometric luminosity by more than two orders of magnitude from the EELR to the nucleus, suggesting that the AGN has decreased in luminosity by this amount in a continuous fashion over 46,000 yr, supporting the case for a dying AGN in this galaxy independent of any IR based evidence. We demonstrate that spatially resolved photoionization modeling could be applied to EELRs to investigate long timescale variability.

  18. Spatially resolved spectra of the 'teacup' active galactic nucleus: tracing the history of a dying quasar

    SciTech Connect

    Gagne, J. P.; Crenshaw, D. M.; Fischer, T. C.; Kraemer, S. B.; Schmitt, H. R.; Keel, W. C.; Rafter, S.; Bennert, V. N.; Schawinski, K.

    2014-09-01

    The Sloan Digital Sky Survey (SDSS) Galaxy Zoo project has revealed a number of spectacular galaxies possessing extended emission-line regions (EELRs), the most famous being Hanny's Voorwerp galaxy. We present another EELR object discovered in the SDSS endeavor: the Teacup active galactic nucleus (AGN). Nicknamed for its EELR, which has a 'handle'-like structure protruding 15 kpc into the northeast quadrant of the galaxy. We analyze the physical conditions of this galaxy with long-slit, ground-based spectroscopy from the Lowell, Lick, and KPNO observatories. With the Lowell 1.8 m Perkin's telescope we took multiple observations at different offset positions, allowing us to recover spatially resolved spectra across the galaxy. Line diagnostics indicate the ionized gas is photoionized primarily by the AGN. Additionally we are able to derive the hydrogen density from the [S II] λ6716/λ6731 ratio. We generated two-component photoionization models for each spatially resolved Lowell spectrum. These models allow us to calculate the AGN bolometric luminosity seen by the gas at different radii from the nuclear center of the Teacup. Our results show a drop in bolometric luminosity by more than two orders of magnitude from the EELR to the nucleus, suggesting that the AGN has decreased in luminosity by this amount in a continuous fashion over 46,000 yr, supporting the case for a dying AGN in this galaxy independent of any IR based evidence. We demonstrate that spatially resolved photoionization modeling could be applied to EELRs to investigate long timescale variability.

  19. Spatial resolved temperature measurement based on absorption spectroscopy using a single tunable diode laser

    NASA Astrophysics Data System (ADS)

    Yu, Xilong; Li, Fei; Chen, Lihong; Zhang, Xinyu

    2010-03-01

    A novel method based on wavelength-multiplexed line-of-sight absorption and profile fitting for non-uniform flow field measurement is reported. A wavelength scanning combing laser temperature and current modulation WMS scheme is used to implement the wavelength-multiplexed-profile fitting method. Second harmonic (2f) signal of eight H2O transitions features near 7,170 cm-1 are measured in one period using a single tunable diode laser. Spatial resolved temperature distribution upon a CH4/air premixed flat flame burner is obtained. The result validates the feasibility of strategy for non-uniform flow field diagnostics by means of WMS-2f TDLAS.

  20. Spatially resolved x-ray spectroscopy investigation of femtosecond laser irradiated Ar clusters.

    PubMed

    Junkel-Vives, G C; Abdallah, J; Auguste, T; D'Oliveira, P; Hulin, S; Monot, P; Dobosz, S; Faenov, A Ya; Magunov, A I; Pikuz, T A; Skobelev, I Yu; Boldarev, A S; Gasilov, V A

    2002-03-01

    High temperature plasmas have been created by irradiating Ar clusters with high intensity 60-fs laser pulses. Detailed spectroscopic analysis of spatially resolved, high resolution x-ray data near the He(alpha) line of Ar is consistent with a two-temperature collisional-radiative model incorporating the effects of highly energetic electrons. The results of the spectral analysis are compared with a theoretical hydrodynamic model of cluster production, as well as interferometric data. The plasma parameters are notably uniform over one Rayleigh length (600 microm). PMID:11909265

  1. Absolute, spatially resolved, in situ CO profiles in atmospheric laminar counter-flow diffusion flames using 2.3 μm TDLAS

    NASA Astrophysics Data System (ADS)

    Wagner, Steven; Klein, Moritz; Kathrotia, Trupti; Riedel, Uwe; Kissel, Thilo; Dreizler, Andreas; Ebert, Volker

    2012-11-01

    We developed a new, spatially traversing, direct tunable diode laser absorption spectrometer (TDLAS) for quantitative, calibration-free, and spatially resolved in situ measurements of CO profiles in atmospheric, laminar, non-premixed CH4/air model flames stabilized at a Tsuji counter-flow burner. The spectrometer employed a carefully characterized, room temperature distributed feedback diode laser to detect the R20 line of CO near 2,313 nm (4,324.4 cm-1), which allows to minimize spectral CH4 interference and detect CO even in very fuel-rich zones of the flame. The burner head was traversed through the 0.5 mm diameter laser beam in order to derive spatially resolved CO profiles in the only 60-mm wide CH4/air flame. Our multiple Voigt line Levenberg-Marquardt fitting algorithm and the use of highly efficient optical disturbance correction algorithms for treating transmission and background emission fluctuations as well as careful fringe interference suppression permitted to achieve a fractional optical resolution of up to 2.4 × 10-4 OD (1σ) in the flame ( T up to 1,965 K). Highly accurate, spatially resolved, absolute gas temperature profiles, needed to compute mole fraction and correct for spectroscopic temperature dependencies, were determined with a spatial resolution of 65 μm using ro-vibrational N2-CARS (Coherent anti-Stokes Raman spectroscopy). With this setup we achieved temperature-dependent CO detection limits at the R20 line of 250-2,000 ppmv at peak CO concentrations of up to 4 vol.%. This permitted local CO detection with signal to noise ratios of more than 77. The CO TDLAS spectrometer was then used to determine absolute, spatially resolved in situ CO concentrations in the Tsuji flame, investigate the strain dependence of the CO Profiles and favorably compare the results to a new flame-chemistry model.

  2. High-fidelity spatially resolved multiphoton counting for quantum imaging applications.

    PubMed

    Chrapkiewicz, Radosław; Wasilewski, Wojciech; Banaszek, Konrad

    2014-09-01

    We present a method for spatially resolved multiphoton counting based on an intensified camera with the retrieval of multimode photon statistics fully accounting for nonlinearities in the detection process. The scheme relies on one-time quantum tomographic calibration of the detector. Faithful, high-fidelity reconstruction of single- and two-mode statistics of multiphoton states is demonstrated for coherent states and their statistical mixtures. The results consistently exhibit classical values of the Mandel parameter and the noise reduction factor in contrast to raw statistics of camera photo-events. Detector operation is reliable for illumination levels up to the average of one detected photon per an event area-substantially higher than in previous approaches to characterize quantum statistical properties of light with spatial resolution. PMID:25166081

  3. Spatially resolved excitation of Rydberg atoms and surface effects on an atom chip

    SciTech Connect

    Tauschinsky, Atreju; Thijssen, Rutger M. T.; Whitlock, S.; Linden van den Heuvell, H. B. van; Spreeuw, R. J. C.

    2010-06-15

    We demonstrate spatially resolved, coherent excitation of Rydberg atoms on an atom chip. Electromagnetically induced transparency (EIT) is used to investigate the properties of the Rydberg atoms near the gold-coated chip surface. We measure distance-dependent shifts ({approx}10 MHz) of the Rydberg energy levels caused by a spatially inhomogeneous electric field. The measured field strength and distance dependence is in agreement with a simple model for the electric field produced by a localized patch of Rb adsorbates deposited on the chip surface during experiments. The EIT resonances remain narrow (<4 MHz) and the observed widths are independent of atom-surface distance down to {approx} 20 {mu}m, indicating relatively long lifetime of the Rydberg states. Our results open the way to studies of dipolar physics, collective excitations, quantum metrology, and quantum information processing involving interacting Rydberg excited atoms on atom chips.

  4. Spatially resolved determination of the dark saturation current of silicon solar cells from electroluminescence images

    NASA Astrophysics Data System (ADS)

    Glatthaar, Markus; Giesecke, Johannes; Kasemann, Martin; Haunschild, Jonas; The, Manuel; Warta, Wilhem; Rein, Stefan

    2009-06-01

    We present a novel method to determine spatially resolved the dark saturation current of standard silicon solar cells. For this two electroluminescence images are taken at two different voltages. From these two images, first the spatial voltage distribution can be calculated. Second by applying the Laplacian to the voltage image from Ohm's law and the continuity equation, the current through the device at a certain position can be determined. Knowing the local current through the device, the local voltage, and the emitter sheet resistance allows to determine the local dark saturation current. The clue of this method is to cope with the noise by using an appropriate noise reduction algorithm. By simulating electroluminescence images with realistic noise and known dark saturation current we demonstrate the applicability of the method with our noise reduction algorithm. Experimentally we compare our method with spectral response light beam induced current on multicrystalline solar cell.

  5. Novel characterization of the nonlinear refractive response of materials using spatially and spectrally resolved interferometry

    NASA Astrophysics Data System (ADS)

    Meier, Amanda; Adams, Daniel; Squier, Jeff; Durfee, Charles

    2010-10-01

    Characterization of the nonlinear refractive index of a material is important in order to fully understand the nonlinear propagation of femtosecond laser pulses. The most common method to obtaining the nonlinear refractive index is Z-scan. However, since it averages over pulse duration and beam profile, Z-scan is not reliable when there is time- and intensity-dependence of the nonlinear response. The new method we are exploring to make these nonlinear refractive index measurements is spatially and spectrally resolved interferometry (SSRI). SSRI is a method that can give a simultaneous measurement of the spatial wave-front across the frequency or temporal profile of the pulse. The SSRI method proves better in measuring response at specific y and t, allowing it to measure both delayed response and saturation effects. The ability to make a measurement in both dimensions enables understanding of spatiotemporal dynamics in other experiments as cross-wave polarization and filamentation.

  6. Evidencing the need for high spatial resolution in angle-resolved photoemission experiments

    NASA Astrophysics Data System (ADS)

    Joucken, Frédéric; Reckinger, Nicolas; Lorcy, Stéphane; Avila, José; Chen, Chaoyu; Lagoute, Jérôme; Colomer, Jean-François; Ghijsen, Jacques; Asensio, Maria Carmen; Sporken, Robert

    2016-06-01

    Angle-resolved photoemission spectroscopy (ARPES) is the most direct tool to measure the electronic structure of materials. In particular, fine features of the spectra can be analyzed for evaluating the electron self-energy. Owing to a setup allowing ARPES investigation with submicron resolution and state-of-the-art energy and momentum resolution, we show here first that ARPES spectra of pristine and virtually undoped monolayer graphene acquired on a small spot do not display manifestations of self-energy. We next demonstrate that, although the region of the sample investigated is a unique graphene domain, it displays faint spatial inhomogeneity, both in its crystallographic orientation and its thickness, which is undetectable with conventional ARPES but renders the spectra improper for self-energy extraction. These results indicate that care should be taken when analyzing ARPES spectra obtained with poor spatial resolution.

  7. Spatially resolved detection of complex ferromagnetic dynamics using optically detected nitrogen-vacancy spins

    NASA Astrophysics Data System (ADS)

    Wolfe, C. S.; Manuilov, S. A.; Purser, C. M.; Teeling-Smith, R.; Dubs, C.; Hammel, P. C.; Bhallamudi, V. P.

    2016-06-01

    We demonstrate optical detection of a broad spectrum of ferromagnetic excitations using nitrogen-vacancy (NV) centers in an ensemble of nanodiamonds. Our recently developed approach exploits a straightforward CW detection scheme using readily available diamond detectors, making it easily implementable. The NV center is a local detector, giving the technique spatial resolution, which here is defined by our laser spot, but in principle can be extended far into the nanoscale. Among the excitations, we observe the propagating dipolar and dipolar-exchange spinwaves, as well as dynamics associated with the multi-domain state of the ferromagnet at low fields. These results offer an approach, distinct from commonly used optically detected magnetic resonance techniques, for spatially resolved spectroscopic study of magnetization dynamics at the nanoscale.

  8. The Discovery of a Spatially Resolved Supernova Remnant in M31 with Chandra

    NASA Astrophysics Data System (ADS)

    Kong, Albert K. H.; Garcia, Michael R.; Primini, Francis A.; Murray, Stephen S.

    2002-12-01

    Chandra observations of M31 allow the first spatially resolved X-ray image of a supernova remnant (SNR) in an external spiral galaxy. CXOM31 J004327.7+411829 is a slightly elongated ring-shaped object with a diameter of ~11" (42 pc). In addition, the X-ray image hints that the chemical composition of the SNR is spatial dependent. The X-ray spectrum of the SNR can be well fitted with a Raymond-Smith model or a nonequilibrium ionization model. Depending on the spectral model, the 0.3-7 keV luminosity is between 3.2×1036 and 4.5×1037 ergs s-1. The age of the SNR is estimated to be 3210-22,300 yr, and the number density of ambient gas is ~0.003-0.3 cm-3. This suggests that the local interstellar medium around the SNR is low.

  9. Spatially resolved excitation temperature measurements in a hypersonic flow using the hook method.

    PubMed

    Sandeman, R J; Ebrahim, N A

    1977-05-01

    The extension of the hook method to include spatial resolution of nonuniformities in the test plane as suggested by Huber (1971) and Sandeman (1971) is demonstrated experimentally by measurements of the variation of the integrated line density of ground state sodium in a flame. Experiments are also described in which the variations in the flow of CO(2) in a hypersonic shock tunnel are spatially resolved along the spectrometer slit. The variations in the hook separations of the 425.4-nm Cr1 resonance and the 434.4-nm CrI 1-eV lower state line are simultaneously measured. The chromium exists as an impurity in the hypersonic flow of CO(2) over a cylinder in a shock tunnel. The populations of the levels so obtained have enabled the comparison of the excitation temperature of the Cr 1-eV level with the calculated gas temperature. PMID:20168704

  10. Determination of optical parameters of human breast tissue from spatially resolved fluorescence: a diffusion theory model

    NASA Astrophysics Data System (ADS)

    Nair, Maya S.; Ghosh, Nirmalya; Raju, Narisetti Sundar; Pradhan, Asima

    2002-07-01

    We report the measurement of optical transport parameters of pathologically characterized malignant tissues, normal tissues, and different types of benign tumors of the human breast in the visible wavelength region. A spatially resolved steady-state diffuse fluorescence reflectance technique was used to estimate the values for the reduced-scattering coefficient (mu's) and the absorption coefficient (mua) of human breast tissues at three wavelengths (530, 550, and 590 nm). Different breast tissues could be well differentiated from one another, and different benign tumors could also be distinguished by their measured transport parameters. A diffusion theory model was developed to describe fluorescence light energy distribution, especially its spatial variation in a turbid and multiply scattering medium such as human tissue. The validity of the model was checked with a Monte Carlo simulation and also with different tissue phantoms prepared with polystyrene microspheres as scatterers, riboflavin as fluorophores, and methylene blue as absorbers.

  11. A simple method for correcting spatially resolved solar intensity oscillation observations for variations in scattered light

    NASA Technical Reports Server (NTRS)

    Jefferies, S. M.; Duvall, T. L., Jr.

    1991-01-01

    A measurement of the intensity distribution in an image of the solar disk will be corrupted by a spatial redistribution of the light that is caused by the earth's atmosphere and the observing instrument. A simple correction method is introduced here that is applicable for solar p-mode intensity observations obtained over a period of time in which there is a significant change in the scattering component of the point spread function. The method circumvents the problems incurred with an accurate determination of the spatial point spread function and its subsequent deconvolution from the observations. The method only corrects the spherical harmonic coefficients that represent the spatial frequencies present in the image and does not correct the image itself.

  12. Catalysts at work: From integral to spatially resolved X-ray absorption spectroscopy

    SciTech Connect

    Grunwaldt, Jan-Dierk; Kimmerle, Bertram; Baiker, Alfons; Boye, Pit; Schroer, Christian G.; Glatzel, Pieter; Borca, Camelia N.; Beckmann, Felix

    2009-09-25

    Spectroscopic studies on heterogeneous catalysts have mostly been done in an integral mode. However, in many cases spatial variations in catalyst structure can occur, e.g. during impregnation of pre-shaped particles, during reaction in a catalytic reactor, or in microstructured reactors as the present overview shows. Therefore, spatially resolved molecular information on a microscale is required for a comprehensive understanding of theses systems, partly in ex situ studies, partly under stationary reaction conditions and in some cases even under dynamic reaction conditions. Among the different available techniques, X-ray absorption spectroscopy (XAS) is a well-suited tool for this purpose as the different selected examples highlight. Two different techniques, scanning and full-field X-ray microscopy/tomography, are described and compared. At first, the tomographic structure of impregnated alumina pellets is presented using full-field transmission microtomography and compared to the results obtained with a scanning X-ray microbeam technique to analyse the catalyst bed inside a catalytic quartz glass reactor. On the other hand, by using XAS in scanning microtomography, the structure and the distribution of Cu(0), Cu(I), Cu(II) species in a Cu/ZnO catalyst loaded in a quartz capillary microreactor could be reconstructed quantitatively on a virtual section through the reactor. An illustrating example for spatially resolved XAS under reaction conditions is the partial oxidation of methane over noble metal-based catalysts. In order to obtain spectroscopic information on the spatial variation of the oxidation state of the catalyst inside the reactor XAS spectra were recorded by scanning with a micro-focussed beam along the catalyst bed. Alternatively, full-field transmission imaging was used to efficiently determine the distribution of the oxidation state of a catalyst inside a reactor under reaction conditions. The new technical approaches together with quantitative data

  13. Spatially resolved hard X-ray polarization in solar flares: effects of Compton scattering and bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Jeffrey, N. L. S.; Kontar, E. P.

    2011-12-01

    Aims: We study the polarization of hard X-ray (HXR) sources in the solar atmosphere, including Compton backscattering of photons in the photosphere (the albedo effect) and the spatial distribution of polarization across the source. Methods: HXR photon polarization and spectra produced via electron-ion bremsstrahlung emission are calculated from various electron distributions typical for solar flares. Compton scattering and photoelectric absorption are then modelled using Monte Carlo simulations of photon transport in the photosphere to study the observed (primary and albedo) sources. Polarization maps across HXR sources (primary and albedo components) for each of the modelled electron distributions are calculated at various source locations from the solar centre to the limb. Results: We show that Compton scattering produces a distinct polarization variation across the albedo patch at peak albedo energies of 20-50 keV for all anisotropies modelled. The results show that there are distinct spatial polarization changes in both the radial and perpendicular to radial directions across the extent of the HXR source at a given disk location. In the radial direction, the polarization magnitude and direction at specific positions along the HXR source will either increase or decrease with increased photon distribution directivity towards the photosphere. We also show how high electron cutoff energies influence the direction of polarization at above ~100 keV. Conclusions: Spatially resolved HXR polarization measurements can provide important information about the directivity and energetics of the electron distribution. Our results indicate the preferred angular resolution of polarization measurements required to distinguish between the scattered and primary components. We also show how spatially resolved polarization measurements could be used to probe the emission pattern of an HXR source, using both the magnitude and the direction of the polarization.

  14. Accurate localization of in-body medical implants based on spatial sparsity.

    PubMed

    Pourhomayoun, Mohammad; Jin, Zhanpeng; Fowler, Mark L

    2014-02-01

    Wearable and implantable wireless communication devices have in recent years gained increasing attention for medical diagnostics and therapeutics. In particular, wireless capsule endoscopy has become a popular method to visualize and diagnose the human gastrointestinal tract. Estimating the exact position of the capsule when each image is taken is a very critical issue in capsule endoscopy. Several approaches have been developed by researchers to estimate the capsule location. However, some unique challenges exist for in-body localization, such as the severe multipath issue caused by the boundaries of different organs, inconsistency of signal propagation velocity and path loss parameters inside the human body, and the regulatory restrictions on using high-bandwidth or high-power signals. In this paper, we propose a novel localization method based on spatial sparsity. We directly estimate the location of the capsule without going through the usual intermediate stage of first estimating time-of-arrival or received-signal strength, and then a second stage of estimating the location. We demonstrate the accuracy of the proposed method through extensive Monte Carlo simulations for radio frequency emission signals within the required power and bandwidth range. The results show that the proposed method is effective and accurate, even in massive multipath conditions. PMID:24108709

  15. Quantitative, depth-resolved determination of particle motion using multi-exposure, spatial frequency domain laser speckle imaging

    PubMed Central

    Rice, Tyler B.; Kwan, Elliott; Hayakawa, Carole K.; Durkin, Anthony J.; Choi, Bernard; Tromberg, Bruce J.

    2013-01-01

    Laser Speckle Imaging (LSI) is a simple, noninvasive technique for rapid imaging of particle motion in scattering media such as biological tissue. LSI is generally used to derive a qualitative index of relative blood flow due to unknown impact from several variables that affect speckle contrast. These variables may include optical absorption and scattering coefficients, multi-layer dynamics including static, non-ergodic regions, and systematic effects such as laser coherence length. In order to account for these effects and move toward quantitative, depth-resolved LSI, we have developed a method that combines Monte Carlo modeling, multi-exposure speckle imaging (MESI), spatial frequency domain imaging (SFDI), and careful instrument calibration. Monte Carlo models were used to generate total and layer-specific fractional momentum transfer distributions. This information was used to predict speckle contrast as a function of exposure time, spatial frequency, layer thickness, and layer dynamics. To verify with experimental data, controlled phantom experiments with characteristic tissue optical properties were performed using a structured light speckle imaging system. Three main geometries were explored: 1) diffusive dynamic layer beneath a static layer, 2) static layer beneath a diffuse dynamic layer, and 3) directed flow (tube) submerged in a dynamic scattering layer. Data fits were performed using the Monte Carlo model, which accurately reconstructed the type of particle flow (diffusive or directed) in each layer, the layer thickness, and absolute flow speeds to within 15% or better. PMID:24409388

  16. Mass Spectrometry Based Imaging Techniques for Spatially Resolved Analysis of Molecules

    PubMed Central

    Matros, Andrea; Mock, Hans-Peter

    2013-01-01

    Higher plants are composed of a multitude of tissues with specific functions, reflected by distinct profiles for transcripts, proteins, and metabolites. Comprehensive analysis of metabolites and proteins has advanced tremendously within recent years, and this progress has been driven by the rapid development of sophisticated mass spectrometric techniques. In most of the current “omics”-studies, analysis is performed on whole organ or whole plant extracts, rendering to the loss of spatial information. Mass spectrometry imaging (MSI) techniques have opened a new avenue to obtain information on the spatial distribution of metabolites and of proteins. Pioneered in the field of medicine, the approaches are now applied to study the spatial profiles of molecules in plant systems. A range of different plant organs and tissues have been successfully analyzed by MSI, and patterns of various classes of metabolites from primary and secondary metabolism could be obtained. It can be envisaged that MSI approaches will substantially contribute to build spatially resolved biochemical networks. PMID:23626593

  17. Spatially resolved δ13C analysis using laser ablation isotope ratio mass spectrometry

    NASA Astrophysics Data System (ADS)

    Moran, J.; Riha, K. M.; Nims, M. K.; Linley, T. J.; Hess, N. J.; Nico, P. S.

    2014-12-01

    Inherent geochemical, organic matter, and microbial heterogeneity over small spatial scales can complicate studies of carbon dynamics through soils. Stable isotope analysis has a strong history of helping track substrate turnover, delineate rhizosphere activity zones, and identifying transitions in vegetation cover, but most traditional isotope approaches are limited in spatial resolution by a combination of physical separation techniques (manual dissection) and IRMS instrument sensitivity. We coupled laser ablation sampling with isotope measurement via IRMS to enable spatially resolved analysis over solid surfaces. Once a targeted sample region is ablated the resulting particulates are entrained in a helium carrier gas and passed through a combustion reactor where carbon is converted to CO2. Cyrotrapping of the resulting CO2 enables a reduction in carrier gas flow which improves overall measurement sensitivity versus traditional, high flow sample introduction. Currently we are performing sample analysis at 50 μm resolution, require 65 ng C per analysis, and achieve measurement precision consistent with other continuous flow techniques. We will discuss applications of the laser ablation IRMS (LA-IRMS) system to microbial communities and fish ecology studies to demonstrate the merits of this technique and how similar analytical approaches can be transitioned to soil systems. Preliminary efforts at analyzing soil samples will be used to highlight strengths and limitations of the LA-IRMS approach, paying particular attention to sample preparation requirements, spatial resolution, sample analysis time, and the types of questions most conducive to analysis via LA-IRMS.

  18. Simulations of the temporal and spatial resolution for a compact time-resolved electron diffractometer

    NASA Astrophysics Data System (ADS)

    Robinson, Matthew S.; Lane, Paul D.; Wann, Derek A.

    2016-02-01

    A novel compact electron gun for use in time-resolved gas electron diffraction experiments has recently been designed and commissioned. In this paper we present and discuss the extensive simulations that were performed to underpin the design in terms of the spatial and temporal qualities of the pulsed electron beam created by the ionisation of a gold photocathode using a femtosecond laser. The response of the electron pulses to a solenoid lens used to focus the electron beam has also been studied. The simulated results show that focussing the electron beam affects the overall spatial and temporal resolution of the experiment in a variety of ways, and that factors that improve the resolution of one parameter can often have a negative effect on the other. A balance must, therefore, be achieved between spatial and temporal resolution. The optimal experimental time resolution for the apparatus is predicted to be 416 fs for studies of gas-phase species, while the predicted spatial resolution of better than 2 nm-1 compares well with traditional time-averaged electron diffraction set-ups.

  19. Monochromatic heterodyne fiber-optic profile sensor for spatially resolved velocity measurements with frequency division multiplexing

    SciTech Connect

    Pfister, Thorsten; Buettner, Lars; Shirai, Katsuaki; Czarske, Juergen

    2005-05-01

    Investigating shear flows is important in technical applications as well as in fundamental research. Velocity measurements with high spatial resolution are necessary. Laser Doppler anemometry allows nonintrusive precise measurements, but the spatial resolution is limited by the size of the measurement volume to {approx}50 {mu}m. A new laser Doppler profile sensor is proposed, enabling determination of the velocity profile inside the measurement volume. Two fringe systems with contrary fringe spacing gradients are generated to determine the position as well as the velocity of passing tracer particles. Physically discriminating between the two measuring channels is done by a frequency-division-multiplexing technique with acousto-optic modulators. A frequency-doubled Nd:YAG laser and a fiber-optic measuring head were employed, resulting in a portable and flexible sensor. In the center of the measurement volume of {approx}1-mm length, a spatial resolution of {approx}5 {mu}m was obtained. Spatially resolved measurements of the Blasius velocity profile are presented. Small velocities as low as 3 cm/s are measured. The sensor is applied in a wind tunnel to determine the wall shear stress of a boundary layer flow. All measurement results show good agreement with the theoretical prediction.

  20. Spatially resolved photoresponse on individual ZnO nanorods: correlating morphology, defects and conductivity

    NASA Astrophysics Data System (ADS)

    Bandopadhyay, K.; Mitra, J.

    2016-06-01

    Electrically active native point defects have a significant impact on the optical and electrical properties of ZnO nanostructures. Control of defect distribution and a detailed understanding of their physical properties are central to designing ZnO in novel functional forms and architecture, which ultimately decides device performance. Defect control is primarily achieved by either engineering nanostructure morphology by tailoring growth techniques or doping. Here, we report conducting atomic force microscopy studies of spatially resolved photoresponse properties on ZnO nanorod surfaces. The photoresponse for super-band gap, ultraviolet excitations show a direct correlation between surface morphology and photoactivity localization. Additionally, the system exhibits significant photoresponse with sub-bandgap, green illumination; the signature energy associated with the deep level oxygen vacancy states. While the local current-voltage characteristics provide evidence of multiple transport processes and quantifies the photoresponse, the local time-resolved photoresponse data evidences large variations in response times (90 ms–50 s), across the surface of a nanorod. The spatially varied photoconductance and the range in temporal response display a complex interplay of morphology, defects and connectivity that brings about the true colour of these ZnO nanostructures.

  1. Spatially resolved photoresponse on individual ZnO nanorods: correlating morphology, defects and conductivity.

    PubMed

    Bandopadhyay, K; Mitra, J

    2016-01-01

    Electrically active native point defects have a significant impact on the optical and electrical properties of ZnO nanostructures. Control of defect distribution and a detailed understanding of their physical properties are central to designing ZnO in novel functional forms and architecture, which ultimately decides device performance. Defect control is primarily achieved by either engineering nanostructure morphology by tailoring growth techniques or doping. Here, we report conducting atomic force microscopy studies of spatially resolved photoresponse properties on ZnO nanorod surfaces. The photoresponse for super-band gap, ultraviolet excitations show a direct correlation between surface morphology and photoactivity localization. Additionally, the system exhibits significant photoresponse with sub-bandgap, green illumination; the signature energy associated with the deep level oxygen vacancy states. While the local current-voltage characteristics provide evidence of multiple transport processes and quantifies the photoresponse, the local time-resolved photoresponse data evidences large variations in response times (90 ms-50 s), across the surface of a nanorod. The spatially varied photoconductance and the range in temporal response display a complex interplay of morphology, defects and connectivity that brings about the true colour of these ZnO nanostructures. PMID:27334573

  2. Spatially resolved photoresponse on individual ZnO nanorods: correlating morphology, defects and conductivity

    PubMed Central

    Bandopadhyay, K.; Mitra, J.

    2016-01-01

    Electrically active native point defects have a significant impact on the optical and electrical properties of ZnO nanostructures. Control of defect distribution and a detailed understanding of their physical properties are central to designing ZnO in novel functional forms and architecture, which ultimately decides device performance. Defect control is primarily achieved by either engineering nanostructure morphology by tailoring growth techniques or doping. Here, we report conducting atomic force microscopy studies of spatially resolved photoresponse properties on ZnO nanorod surfaces. The photoresponse for super-band gap, ultraviolet excitations show a direct correlation between surface morphology and photoactivity localization. Additionally, the system exhibits significant photoresponse with sub-bandgap, green illumination; the signature energy associated with the deep level oxygen vacancy states. While the local current-voltage characteristics provide evidence of multiple transport processes and quantifies the photoresponse, the local time-resolved photoresponse data evidences large variations in response times (90 ms–50 s), across the surface of a nanorod. The spatially varied photoconductance and the range in temporal response display a complex interplay of morphology, defects and connectivity that brings about the true colour of these ZnO nanostructures. PMID:27334573

  3. Differentiation of microstructures of sugar foams by means of spatially resolved spectroscopy

    NASA Astrophysics Data System (ADS)

    Nguyen Do Trong, Nghia; Watte, Rodrigo; Aernouts, Ben; Verhoelst, Eva; Tsuta, Mizuki; Jakubczyk, Ewa; Gondek, Ewa; Verboven, Pieter; Nicolaï, Bart M.; Saeys, Wouter

    2012-04-01

    Food quality is critically determined by its microstructure and composition. These properties could be quantified noninvasively by means of optical properties (absorption and reduced scattering coefficients) of the food samples. In this research, a spatially-resolved spectroscopy setup based on a fiber-optic probe was developed for acquiring spatiallyresolved diffuse reflectance of three sugar foams with different designed microstructures in the range 500 - 1000 nm. A model for light propagation in turbid media based on diffusion approximation for solving the radiative transport equation was employed to derive optical properties (absorption and reduced scattering coefficients) of these foams. The accuracy of this light propagation model was validated on four liquid phantoms with known optical properties. The obtained results indicated that the optical properties estimation was successfully validated on these liquid phantoms. The estimated reduced scattering coefficients μs' of the foams clearly showed the effect of foaming time on their microstructures. The acquired absorption coefficients μa were also in good agreement with the designed ingredients of these sugar foams. The research results clearly support the potential of spatially-resolved spectroscopy for nondestructive food quality inspection and process monitoring in the food industry.

  4. Spatially resolved hazard and exposure assessments: an example of lead in soil at Lavrion, Greece.

    PubMed

    Tristán, E; Demetriades, A; Ramsey, M H; Rosenbaum, M S; Stavrakis, P; Thornton, I; Vassiliades, E; Vergou, K

    2000-01-01

    Spatially resolved hazard assessment (SRHA) and spatially resolved exposure assessment (SREA) are methodologies that have been devised for assessing child exposure to soil containing environmental pollutants. These are based on either a quantitative or a semiquantitative approach. The feasibility of the methodologies has been demonstrated in a study assessing child exposure to Pb accessible in soil at the town of Lavrion in Greece. Using a quantitative approach, both measured and kriged concentrations of Pb in soil are compared with an "established" statutory threshold value. The probabilistic approach gives a refined classification of the contaminated land, since it takes into consideration the uncertainty in both the actual measurement and estimated kriged values. Two exposure assessment models (i.e., IEUBK and HESP) are used as the basis of the quantitative SREA methodologies. The significant correlation between the blood-Pb predictions, using the IEUBK model, and measured concentrations provides a partial validation of the method, because it allows for the uncertainty in the measurements and the lack of some site-specific measurements. The semiquantitative applications of SRHA and SREA incorporate both qualitative information (e.g., land use and dustiness of waste) and quantitative information (e.g., distance from wastes and distance from industry). The significant correlation between the results of these assessments and the measured blood-Pb levels confirms the robust nature of this approach. Successful application of these methodologies could reduce the cost of the assessment and allow areas to be prioritized for further investigation, remediation, or risk management. PMID:10677144

  5. Nitrogenase FeMoco investigated by spatially resolved anomalous dispersion refinement

    PubMed Central

    Spatzal, Thomas; Schlesier, Julia; Burger, Eva-Maria; Sippel, Daniel; Zhang, Limei; Andrade, Susana L.A.; Rees, Douglas C.; Einsle, Oliver

    2016-01-01

    The [Mo:7Fe:9S:C] iron-molybdenum cofactor (FeMoco) of nitrogenase is the largest known metal cluster and catalyses the 6-electron reduction of dinitrogen to ammonium in biological nitrogen fixation. Only recently its atomic structure was clarified, while its reactivity and electronic structure remain under debate. Here we show that for its resting S=3/2 state the common iron oxidation state assignments must be reconsidered. By a spatially resolved refinement of the anomalous scattering contributions of the 7 Fe atoms of FeMoco, we conclude that three irons (Fe1/3/7) are more reduced than the other four (Fe2/4/5/6). Our data are in agreement with the recently revised oxidation state assignment for the molybdenum ion, providing the first spatially resolved picture of the resting-state electron distribution within FeMoco. This might provide the long-sought experimental basis for a generally accepted theoretical description of the cluster that is in line with available spectroscopic and functional data. PMID:26973151

  6. Spatially resolved resistance of NiO nanostructures under humid environment

    SciTech Connect

    Jacobs, Christopher B; Ievlev, Anton; Collins, Liam F; Muckley, Eric S; Joshi, Pooran C; Ivanov, Ilia N

    2016-01-01

    The spatially resolved electrical response of polycrystalline NiO films composed of 40 nm crystallites was investigated under different relative humidity levels (RH). The topological and electrical properties (surface potential and resistance) were characterized with sub 25nm resolution using Kelvin probe force microscopy (KPFM) and conductive scanning probe microscopy under argon atmosphere at 0%, 50%, and 80% relative humidity. The dimensionality of surface features obtained through autocorrelation analysis of topological maps increased linearly with increased relative humidity, as water was adsorbed onto the film surface. Surface potential decreased from about 280mV to about 100 mV and resistance decreased from about 5 G to about 3 G , in a nonlinear fashion when relative humidity was increased from 0% to 80%. Spatially resolved surface potential and resistance of the NiO films was found to be heterogeneous throughout the film, with distinct domains that grew in size from about 60 nm to 175 nm at 0% and 80% RH levels, respectively. The heterogeneous character of the topological, surface potential, and resistance properties of the polycrystalline NiO film observed under dry conditions decreased with increased relative humidity, yielding nearly homogeneous surface properties at 80% RH, suggesting that the nanoscale potential and resistance properties converge with the mesoscale properties as water is adsorbed onto the NiO film.

  7. Spatially resolved hazard and exposure assessments: An example of lead in soil at Lavrion, Greece

    SciTech Connect

    Tristan, E.; Demetriades, A.; Ramsey, M.H.; Rosenbaum, M.S.; Stavrakis, P.; Thornton, I.; Vassiliades, E.; Vergou, K.

    2000-01-01

    Spatially resolved hazard assessment (SRHA) and spatially resolved exposure assessment (SREA) are methodologies that have been devised for assessing child exposure to soil containing environmental pollutants. These are based on either a quantitative or a semiquantitative approach. The feasibility of the methodologies has been demonstrated in a study assessing child exposure to Pb accessible in soil at the town of Lavrion in Greece. Using a quantitative approach, both measured and kriged concentrations of Pb in soil are compared with an established statutory threshold value. The probabilistic approach gives a refined classification of the contaminated land, since it takes into consideration the uncertainty in both the actual measurement and estimated kriged values. Two exposure assessment models (i.e., IEUBK and HESP) are used as the basis of the quantitative SREA methodologies. The significant correlation between the blood-Pb predictions, using the IEUBK model, and measured concentrations provides a partial validation of the method, because it allows for the uncertainty in the measurements and the lack of some site-specific measurements. The semiquantitative applications of SRHA and SREA incorporate both qualitative information (e.g., land use and dustiness of waste) and quantitative information (e.g., distance from wastes and distance from industry). The significant correlation between the results of these assessments and the measured blood-Pb levels confirms the robust nature of this approach. Successful application of these methodologies could reduce the cost of the assessment and allow areas to be prioritized for further investigation, remediation, or risk management.

  8. Spatially Resolved Quantification of Chromatin Condensation through Differential Local Rheology in Cell Nuclei Fluorescence Lifetime Imaging

    PubMed Central

    Spagnol, Stephen T.; Dahl, Kris Noel

    2016-01-01

    The linear sequence of DNA encodes access to the complete set of proteins that carry out cellular functions. Yet, much of the functionality appropriate for each cell is nested within layers of dynamic regulation and organization, including a hierarchy of chromatin structural states and spatial arrangement within the nucleus. There remain limitations in our understanding of gene expression within the context of nuclear organization from an inability to characterize hierarchical chromatin organization in situ. Here we demonstrate the use of fluorescence lifetime imaging microscopy (FLIM) to quantify and spatially resolve chromatin condensation state using cell-permeable, DNA-binding dyes (Hoechst 33342 and PicoGreen). Through in vitro and in situ experiments we demonstrate the sensitivity of fluorescence lifetime to condensation state through the mechanical effects that accompany the structural changes and are reflected through altered viscosity. The establishment of FLIM for resolving and quantifying chromatin condensation state opens the door for single-measurement mechanical studies of the nucleus and for characterizing the role of genome structure and organization in nuclear processes that accompany physiological and pathological changes. PMID:26765322

  9. Spatially Resolved Quantification of Chromatin Condensation through Differential Local Rheology in Cell Nuclei Fluorescence Lifetime Imaging.

    PubMed

    Spagnol, Stephen T; Dahl, Kris Noel

    2016-01-01

    The linear sequence of DNA encodes access to the complete set of proteins that carry out cellular functions. Yet, much of the functionality appropriate for each cell is nested within layers of dynamic regulation and organization, including a hierarchy of chromatin structural states and spatial arrangement within the nucleus. There remain limitations in our understanding of gene expression within the context of nuclear organization from an inability to characterize hierarchical chromatin organization in situ. Here we demonstrate the use of fluorescence lifetime imaging microscopy (FLIM) to quantify and spatially resolve chromatin condensation state using cell-permeable, DNA-binding dyes (Hoechst 33342 and PicoGreen). Through in vitro and in situ experiments we demonstrate the sensitivity of fluorescence lifetime to condensation state through the mechanical effects that accompany the structural changes and are reflected through altered viscosity. The establishment of FLIM for resolving and quantifying chromatin condensation state opens the door for single-measurement mechanical studies of the nucleus and for characterizing the role of genome structure and organization in nuclear processes that accompany physiological and pathological changes. PMID:26765322

  10. Spatially Resolved Dust Maps from Balmer Decrements in Galaxies at z ~ 1.4

    NASA Astrophysics Data System (ADS)

    Nelson, Erica June; van Dokkum, Pieter G.; Momcheva, Ivelina G.; Brammer, Gabriel B.; Wuyts, Stijn; Franx, Marijn; Förster Schreiber, Natascha M.; Whitaker, Katherine E.; Skelton, Rosalind E.

    2016-01-01

    We derive average radial gradients in the dust attenuation toward H ii regions in 609 galaxies at z ˜ 1.4, using measurements of the Balmer decrement out to r ˜ 3 kpc. The Balmer decrements are derived from spatially resolved maps of Hα and Hβ emission from the 3D-HST survey. We find that with increasing stellar mass M both the normalization and strength of the gradient in dust attenuation increases. Galaxies with a mean mass of < {log} M> =9.2M⊙ have little dust attenuation at all radii, whereas galaxies with < {log} M> =10.2M⊙ have AHα ≈ 2 mag in their central regions. We parameterize this as {A}{{H}α }=b+c{log} r, with b=0.9+{log}1.0{M}10, c = -1.9-2.2 log M10, r in kpc, and M10 the stellar mass in units of 1010 M⊙. This expression can be used to correct spatially resolved measurements of Hα to radial distributions of star formation. When applied to our data, we find that the star formation rates (SFRs) in the central r < 1 kpc of galaxies in the highest mass bin are ˜6 M⊙ yr-1, six times higher than before correction and approximately half of the total SFR of these galaxies. If this high central SFR is maintained for several Gyr, a large fraction of the stars in present-day bulges likely formed in situ.

  11. Development of dispersive XAFS system for analysis of time-resolved spatial distribution of electrode reaction.

    PubMed

    Katayama, Misaki; Miyahara, Ryota; Watanabe, Toshiki; Yamagishi, Hirona; Yamashita, Shohei; Kizaki, Terue; Sugawara, Yoshimi; Inada, Yasuhiro

    2015-09-01

    Apparatus for a technique based on the dispersive optics of X-ray absorption fine structure (XAFS) has been developed at beamline BL-5 of the Synchrotron Radiation Center of Ritsumeikan University. The vertical axis of the cross section of the synchrotron light is used to disperse the X-ray energy using a cylindrical polychromator and the horizontal axis is used for the spatially resolved analysis with a pixel array detector. The vertically dispersive XAFS (VDXAFS) instrument was designed to analyze the dynamic changeover of the inhomogeneous electrode reaction of secondary batteries. The line-shaped X-ray beam is transmitted through the electrode sample, and then the dispersed transmitted X-rays are detected by a two-dimensional detector. An array of XAFS spectra in the linear footprint of the transmitted X-ray on the sample is obtained with the time resolution of the repetition frequency of the detector. Sequential measurements of the space-resolved XAFS data are possible with the VDXAFS instrument. The time and spatial resolutions of the VDXAFS instrument depend on the flux density of the available X-ray beam and the size of the light source, and they were estimated as 1 s and 100 µm, respectively. The electrode reaction of the LiFePO4 lithium ion battery was analyzed during the constant current charging process and during the charging process after potential jumping. PMID:26289274

  12. Spatially resolved information on karst conduit flow from in-cave dye-tracing

    NASA Astrophysics Data System (ADS)

    Lauber, U.; Ufrecht, W.; Goldscheider, N.

    2013-09-01

    Artificial tracers are powerful tools to investigate karst systems. Tracers are commonly injected into sinking streams or dolines, while springs serve as monitoring sites. The obtained flow and transport parameters represent mixed information from the vadose, epiphreatic and phreatic zones, i.e., the aquifer remains a black box. Accessible active caves constitute valuable but underexploited natural laboratories to gain detailed insights into the hydrologic functioning of the aquifer. Two multi-tracer tests in the catchment of a major karst spring (Blautopf, Germany) with injections and monitoring in two associated water caves aimed at obtaining spatially and temporally resolved information on groundwater flow in different compartments of the system. Two tracers were injected in the caves to characterize the hydraulic connections between them and with the spring. Two injections at the land surface, far from the spring, aimed at resolving the aquifer's internal drainage structure. Tracer breakthrough curves were monitored by field fluorimeters in caves and at the spring. Results demonstrate the dendritic drainage structure of the aquifer. It was possible to obtain relevant flow and transport parameters for different sections of this system. The highest mean flow velocities (275 m h-1) were observed in the near-spring epiphreatic section (open-channel flow), while velocities in the phreatic zone (pressurized flow) were one order of magnitude lower. Determined conduit water volumes confirm results of water balances and hydrograph analyses. In conclusion, experiments and monitoring in caves can deliver spatially resolved information on karst aquifer heterogeneity and dynamics that cannot be obtained by traditional investigative methods.

  13. Spatially resolved information on karst conduit flow from in-cave dye tracing

    NASA Astrophysics Data System (ADS)

    Lauber, U.; Ufrecht, W.; Goldscheider, N.

    2014-02-01

    Artificial tracers are powerful tools for investigating karst systems. Tracers are commonly injected into sinking streams or dolines, while springs serve as monitoring sites. The obtained flow and transport parameters represent mixed information from the vadose, epiphreatic and phreatic zones (that is, the aquifer remains a black box). Accessible active caves constitute valuable but underexploited natural laboratories to gain detailed insights into the hydrologic functioning of the aquifer. Two multi-tracer tests in the catchment of a major karst spring (Blautopf, Germany) with injections and monitoring in two associated water caves aimed at obtaining spatially and temporally resolved information on groundwater flow in different compartments of the system. Two tracers were injected into the caves to characterize the hydraulic connections between them and with the spring. Two injections at the land surface, far from the spring, aimed at resolving the aquifer's internal drainage structure. Tracer breakthrough curves were monitored by field fluorimeters in caves and at the spring. Results demonstrate the dendritic drainage structure of the aquifer. It was possible to obtain relevant flow and transport parameters for different sections of this system. The highest mean flow velocities (275 m h-1) were observed in the near-spring epiphreatic section (open-channel flow), while velocities in the phreatic zone (pressurized flow) were one order of magnitude lower. Determined conduit water volumes confirm results of water balances and hydrograph analyses. In conclusion, experiments and monitoring in caves can deliver spatially resolved information on karst aquifer heterogeneity and dynamics that cannot be obtained by traditional investigative methods.

  14. Spatially Resolved Temperature and Water Vapor Concentration Distributions in Supersonic Combustion Facilities by TDLAT

    NASA Technical Reports Server (NTRS)

    Busa, K. M.; McDaniel J. C.; Diskin, G. S.; DePiro, M. J.; Capriotti, D. P.; Gaffney, R. L.

    2012-01-01

    Detailed knowledge of the internal structure of high-enthalpy flows can provide valuable insight to the performance of scramjet combustors. Tunable Diode Laser Absorption Spectroscopy (TDLAS) is often employed to measure temperature and species concentration. However, TDLAS is a path-integrated line-of-sight (LOS) measurement, and thus does not produce spatially resolved distributions. Tunable Diode Laser Absorption Tomography (TDLAT) is a non-intrusive measurement technique for determining two-dimensional spatially resolved distributions of temperature and species concentration in high enthalpy flows. TDLAT combines TDLAS with tomographic image reconstruction. More than 2500 separate line-of-sight TDLAS measurements are analyzed in order to produce highly resolved temperature and species concentration distributions. Measurements have been collected at the University of Virginia's Supersonic Combustion Facility (UVaSCF) as well as at the NASA Langley Direct-Connect Supersonic Combustion Test Facility (DCSCTF). Due to the UVaSCF s unique electrical heating and ability for vitiate addition, measurements collected at the UVaSCF are presented as a calibration of the technique. Measurements collected at the DCSCTF required significant modifications to system hardware and software designs due to its larger measurement area and shorter test duration. Tomographic temperature and water vapor concentration distributions are presented from experimentation on the UVaSCF operating at a high temperature non-reacting case for water vitiation level of 12%. Initial LOS measurements from the NASA Langley DCSCTF operating at an equivalence ratio of 0.5 are also presented. Results show the capability of TDLAT to adapt to several experimental setups and test parameters.

  15. Measurement of the optical properties of fruits and vegetables using spatially resolved hyperspectral diffuse reflectance imaging technique

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper reports on the measurement of the optical properties of fresh fruits and vegetables over the visible and short-wave near-infrared region using a spatially resolved steady-state diffuse reflectance technique. A hyperspectral imaging system in line scan mode was used to acquire spatially re...

  16. A comparison of magnetic resonance methods for spatially resolved T2 distribution measurements in porous media

    NASA Astrophysics Data System (ADS)

    Vashaee, S.; Marica, F.; Newling, B.; Balcom, B. J.

    2015-05-01

    Naturally occurring porous media are usually characterized by a distribution of pore sizes. If the material is fluid saturated, the 1H magnetic resonance (MR) signal depends on the pore size, the surface relaxivity and the fluid itself. Measurement of the transverse relaxation time T2 is a well-established technique to characterize material samples by means of MR. T2 distribution measurements, including T2 distribution mapping, are widely employed in clinical applications and in petroleum engineering. T2 distribution measurements are the most basic measurement employed to determine the fluid-matrix properties in MR core analysis. Three methods for T2 distribution mapping, namely spin-echo single point imaging (SE-SPI), DANTE-Z Carr-Purcell-Meiboom-Gill (CPMG) and adiabatic inversion CPMG are compared in terms of spatial resolution, minimum observable T2 and sensitivity. Bulk CPMG measurement is considered to be the gold standard for T2 determination. Bulk measurement of uniform samples is compared to the three spatially resolved measurements. SE-SPI is an imaging method, which measures spatially resolved T2s in samples of interest. A variant is introduced in this work that employs pre-equalized magnetic field gradient waveforms and is therefore able to measure shorter T2s than previously reported. DANTE-Z CPMG and adiabatic inversion CPMG are faster, non-imaging, local T2 distribution measurements. The DANTE-Z pulse train and adiabatic inversion pulse are compared in terms of T1 or T2 relaxation time effects during the RF pulse application, minimum pulse duration, requisite RF pulse power, and inversion profile quality. In addition to experimental comparisons, simulation results are presented.

  17. [The spatial frequency limits and the resolving power of the visual system of the pigeon].

    PubMed

    Pak, M A; Cleveland, S J

    1991-12-01

    The spatial contrast transfer function of the visual system of the pigeon was determined by recording from the optic tectum evoked potentials or extracellular unit activity in response to a pattern stimulus contrast transfer function, determined as a "response function", describes the relationship between the contrast in the pattern--which consisted of vertically oriented stripes of sinusoidally varying luminance--and the amplitude of the response at various spatial frequencies (c/deg). The transfer function yields an estimate of the high frequency limit, which in turn is a measure of visual resolving power. Action potentials were recorded extracellularly using glass microelectrodes; for evoked potentials, stainless steel electrodes were used. Recordings were made from the stratum griseum et fibrosum superficiale of the optic tectum. The highest spatial frequency detectable in a visual system is limited by various factors, including the diffraction of light at the pupil and the anatomical spacing of the photoreceptors. The pupil factor can be controlled in experiments in a suitable way. In this paper, the electrophysiologically determined high-frequency limit was compared with the theoretical resolution limit imposed by the photoreceptor mosaic. The experimental results show that the visual system of the pigeon has a high-frequency limit at a spatial frequency of 15.5 c/deg, corresponding to a visual acuity of 1.9 min of arc. The attempt to relate visual acuity in the pigeon to the anatomical spacing of the photoreceptors shows that the Nyquist frequency of the photoreceptor mosaic, the theoretical upper bound of the spatial resolution, agrees with measurement. PMID:1786779

  18. Spatially resolved measurements of mean spin-spin relaxation time constants

    NASA Astrophysics Data System (ADS)

    Nechifor, Ruben Emanuel; Romanenko, Konstantin; Marica, Florea; Balcom, Bruce J.

    2014-02-01

    Magnetic Resonance measurements of the T2 distribution have become very common and they are a powerful way to probe microporous fluid bearing solids. While the structure of the T2 distribution, and changes in the structure, are often very informative, it is common to reduce the T2 distribution to a mean numeric quantity in order to provide a quantitative interpretation of the distribution. Magnetic Resonance Imaging measurements of the T2 distribution have recently been introduced, but they are time consuming, especially for 2 and 3 spatial dimensions. In this paper we explore a direct MRI measurement of the arithmetic mean of 1/T2, characterizing the distribution by using the initial slope of the spatially resolved T2 decay in a CPMG prepared Centric Scan SPRITE experiment. The methodology is explored with a test phantom sample and realistic petroleum reservoir core plug samples. The arithmetic mean of 1/T2 is related to the harmonic mean of T2. The mean obtained from the early decay is explored through measurements of uniform saturated core plug samples and by comparison to other means determined from the complete T2 distribution. Complementary data were obtained using SE-SPI T2 distribution MRI measurements. The utility of the arithmetic mean 1/T2 is explored through measurements of centrifuged core plug samples where the T2 distribution varies spatially. The harmonic mean T2 obtained from the early decay was employed to estimate the irreducible water saturation for core plug samples.

  19. Spatially and angularly resolved cathodoluminescence study of single ZnO nanorods.

    PubMed

    Li, Chengyao; Gao, Min; Zhang, Xiaoxian; Peng, Lian-Mao; Chen, Qing

    2010-11-01

    Single ZnO nanorods were studied with cathodoluminescence at high spatial and angular resolution. A newly developed luminescence detector consisting a fiber probe controlled by a nano-manipulator is attached to a scanning electron microscope to carry out the cathodoluminescence measurements. Excitonic emission from the sidewalls and redshifted near band edge emission guided along the nanorod axis are observed as the fiber probe axis is aligned to be perpendicular and parallel to the nanorod axis, respectively, demonstrating the angular resolving power of the experimental setup and waveguiding behavior of the nanorods. High spatial resolution cathodoluminescence measurement shows that the near band edge emission can propagate parallel and perpendicular to the nanorod axis and an increased propagation distance results in more redshift of the guided luminescence. In addition, the high spatial resolution and temperature dependent cathodoluminescence measurements demonstrate the important role of free exciton-longitudinal optical phonon interaction in the waveguiding behavior and the propagation of the near band edge emission in ZnO nanorods. PMID:21137887

  20. Spectrally and spatially resolved cathodoluminescence of nanodiamonds: local variations of the NV(0) emission properties.

    PubMed

    Tizei, L H G; Kociak, M

    2012-05-01

    Here we report the spectrally and spatially resolved cathodoluminescence of diamond nanoparticles using focused fast electron beams in a transmission electron microscope. We demonstrate the possibility of quickly detecting various individual colour centres of different kinds on wide areas (several micrometres square) contained in nanoparticles separated by subwavelength distances. Among them, nanoparticles containing one or more neutral nitrogen-vacancy (NV(0)) intensity maxima have been seen, attributable to individual emitters. Thanks to a spatial resolution which is solely limited by charge carrier diffusion in the case of a fast electron (80 keV) setup, the spectra of two individual NV(0) emitters separated by 80 nm inside a nanoparticle have been spatially discerned. A shift of the zero phonon line (ZPL) between the two emitters, which we attribute to internal stress, is shown to arise even within the same nanoparticle. Detailed emission spectra (ZPL, phonon lines and Huang-Rhys factor, directly linked to the relaxation energy of the colour centre) in 51 individual NV(0) centres have been measured in 39 particles. The ZPL and Huang-Rhys factor are found to be measurably dispersed, while the phonon energies keep constant. PMID:22481219

  1. Spatially resolved measurements of mean spin-spin relaxation time constants.

    PubMed

    Nechifor, Ruben Emanuel; Romanenko, Konstantin; Marica, Florea; Balcom, Bruce J

    2014-02-01

    Magnetic Resonance measurements of the T2 distribution have become very common and they are a powerful way to probe microporous fluid bearing solids. While the structure of the T2 distribution, and changes in the structure, are often very informative, it is common to reduce the T2 distribution to a mean numeric quantity in order to provide a quantitative interpretation of the distribution. Magnetic Resonance Imaging measurements of the T2 distribution have recently been introduced, but they are time consuming, especially for 2 and 3 spatial dimensions. In this paper we explore a direct MRI measurement of the arithmetic mean of 1/T2, characterizing the distribution by using the initial slope of the spatially resolved T2 decay in a CPMG prepared Centric Scan SPRITE experiment. The methodology is explored with a test phantom sample and realistic petroleum reservoir core plug samples. The arithmetic mean of 1/T2 is related to the harmonic mean of T2. The mean obtained from the early decay is explored through measurements of uniform saturated core plug samples and by comparison to other means determined from the complete T2 distribution. Complementary data were obtained using SE-SPI T2 distribution MRI measurements. The utility of the arithmetic mean 1/T2 is explored through measurements of centrifuged core plug samples where the T2 distribution varies spatially. The harmonic mean T2 obtained from the early decay was employed to estimate the irreducible water saturation for core plug samples. PMID:24361482

  2. Peach maturity/quality assessment using hyperspectral imaging-based spatially resolved technique

    NASA Astrophysics Data System (ADS)

    Cen, Haiyan; Lu, Renfu; Mendoza, Fernando A.; Ariana, Diwan P.

    2011-06-01

    The objective of this research was to measure the absorption (μa) and reduced scattering coefficients (μs') of peaches, using a hyperspectral imaging-based spatially-resolved method, for their maturity/quality assessment. A newly developed optical property measuring instrument was used for acquiring hyperspectral reflectance images of 500 'Redstar' peaches. μa and μs' spectra for 515-1,000 nm were extracted from the spatially-resolved reflectance profiles using a diffusion model coupled with an inverse algorithm. The absorption spectra of peach fruit presented several absorption peaks around 525 nm for anthocyanin, 620 nm for chlorophyll-b, 675 nm for chlorophyll-a, and 970 nm for water, while μs' decreased consistently with the increase of wavelength for most of the tested samples. Both μa and μs' were correlated with peach firmness, soluble solids content (SSC), and skin and flesh color parameters. Better prediction results for partial least squares models were obtained using the combined values of μa and μs' (i.e., μa × μs' and μeff) than using μa or μs', where μeff = [3 μa (μa + μs')]1/2 is the effective attenuation coefficient. The results were further improved using least squares support vector machine models with values of the best correlation coefficient for firmness, SSC, skin lightness and flesh lightness being 0.749 (standard error of prediction or SEP = 17.39 N), 0.504 (SEP = 0.92 °Brix), 0.898 (SEP = 3.45), and 0.741 (SEP = 3.27), respectively. These results compared favorably to acoustic and impact firmness measurements with the correlation coefficient of 0.639 and 0.631, respectively. Hyperspectral imaging-based spatially-resolved technique is useful for measuring the optical properties of peach fruit, and it also has good potential for assessing fruit maturity/quality attributes.

  3. The effects of the atmospheric point-spread 'seeing' function on spatially resolved spectra of Jupiter

    NASA Technical Reports Server (NTRS)

    Gelfand, J.; Cochran, W. D.; Smith, W. H.

    1977-01-01

    We present the results of an analysis of the effects of atmospheric seeing and of instrumental spectral and spatial resolution on the observed variation of absorption-line profiles across the disk of Jupiter. The technique described may be applied equally well to the analysis of observations of any extended astronomical source. These results show the necessity of obtaining accurate point-spread-function information during the course of observations of this nature. We also point out that in order to avoid the uncertainties and ambiguities inherent in attempts at deconvolution of observational data, one must properly convolve the appropriate spatial and spectral resolution functions with the models being tested and then compare the results with the observational data.

  4. Spatially Resolving Spectroscopic Binaries with the CHARA Array: The SFP Project

    NASA Astrophysics Data System (ADS)

    Farrington, C. D.; ten Brummelaar, T. A.

    2013-02-01

    When observed with optical long-baseline interferometers (OLBI), components of a binary star which are sufficiently separated such that their interferometric fringe packets do not overlap are referred to as Separated Fringe Packet (SFP) binaries. These SFP binaries extend out into the regime of systems resolvable by speckle interferometry at single, large-aperture telescopes and can provide additional measurements for preliminary orbits lacking good phase coverage, help constrain elements of already established orbits, and locate new binaries in the undersampled regime between the bounds of spectroscopic surveys and speckle interferometry. In this process, a visibility calibration star is not needed, and the separated fringe packets can provide an accurate vector separation. Presented here we describe the method, usage, and modified orbits for several systems used to validate the procedure.

  5. Spatially and Temporally Resolved Studies of the Human Microbiome (2011 JGI User Meeting)

    SciTech Connect

    Knight, Rob

    2011-03-23

    The U.S. Department of Energy Joint Genome Institute (JGI) invited scientists interested in the application of genomics to bioenergy and environmental issues, as well as all current and prospective users and collaborators, to attend the annual DOE JGI Genomics of Energy & Environment Meeting held March 22-24, 2011 in Walnut Creek, Calif. The emphasis of this meeting was on the genomics of renewable energy strategies, carbon cycling, environmental gene discovery, and engineering of fuel-producing organisms. The meeting features presentations by leading scientists advancing these topics. Rob Knight of the University of Colorado gives a presentation on "Spatially and Temporally Resolved Studies of the Human Microbiome" at the 6th annual Genomics of Energy & Environment Meeting on March 23, 2011

  6. Time, Energy, and Spatially Resolved TEM Investigations of Defectsin InGaN

    SciTech Connect

    Jinschek, J.R.; Kisielowski, C.

    2005-10-01

    A novel sample preparation technique is reported to fabricate electron transparent samples from devices utilizing a FIB process with a successive wet etching step. The high quality of the obtained samples allows for band gap--and chemical composition measurements of In{sub x}Ga{sub 1-x}N quantum wells where electron beam induced damage can be controlled and shown to be negligible. The results reveal indium enrichment in nanoclusters and defects that cause fluctuations of the band gap energy and can be measured by low loss Electron Energy Spectroscopy with nm resolution. Comparing our time, energy, and spatially resolved measurements of band gap energies, chemical composition, and their related fluctuations with literature data, we find quantitative agreement if the band gap energy of InN is 1.5-2 eV.

  7. Spatially and Temporally Resolved Studies of the Human Microbiome (2011 JGI User Meeting)

    ScienceCinema

    Knight, Rob [University of Colorado

    2011-06-03

    The U.S. Department of Energy Joint Genome Institute (JGI) invited scientists interested in the application of genomics to bioenergy and environmental issues, as well as all current and prospective users and collaborators, to attend the annual DOE JGI Genomics of Energy & Environment Meeting held March 22-24, 2011 in Walnut Creek, Calif. The emphasis of this meeting was on the genomics of renewable energy strategies, carbon cycling, environmental gene discovery, and engineering of fuel-producing organisms. The meeting features presentations by leading scientists advancing these topics. Rob Knight of the University of Colorado gives a presentation on "Spatially and Temporally Resolved Studies of the Human Microbiome" at the 6th annual Genomics of Energy & Environment Meeting on March 23, 2011

  8. Spatially resolved element analysis of historical violin varnishes by use of muPIXE.

    PubMed

    von Bohlen, Alex; Röhrs, Stefan; Salomon, Joseph

    2007-02-01

    External muPIXE has been used for characterisation of small samples of varnish from historical violins, and pieces of varnished wood from historical and modern stringed instruments. To obtain spatially resolved information about the distribution of elements across the varnish layers single-spot analysis, line-scans, and area-mapping were performed. Local resolution of approximately 20 mum was obtained from the 3 MeV, 1 nA proton micro-probe. Results from simultaneous multi-element determination of Na, Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Rb, Sr, Ag, Cd, Sn, Ba, and Pb in historical varnishes are presented. Semi-quantitative evaluation of line-scans recorded on diverse historical varnishes is reported. The applied method is discussed in detail and the results obtained are critically reviewed and compared with those in the literature. PMID:17047941

  9. Spatially-resolved investigation of transport in semiconductors: a photothermal deflection approach

    SciTech Connect

    Skumanich, A.; Fournier, D.; Boccara, A.C.; Amer, N.M.

    1985-06-01

    The unique ability of photothermal deflection spectroscopy to probe the local index of refraction of matter is exploited to investigate, in a spatially-resolved manner, thermal and electronic transport in semiconductors. An added advantage of this approach is that it is contactless; hence, it obviates the classical problems associated with electrodes and contacts. The basic premise of the technique is the use of the heat associated with non-radiative processes (e.g., recombination of carriers) to deflect a focussed laser probe beam (sub-gap energy) propagating through the semiconductor. The deflection of the probe beam is caused by a change in the refractive index of the sample which is in turn governed by carrier diffusion and recombination.

  10. The Fossil Record of Black Hole Seeds, with Spatially Resolved Spectroscopy

    NASA Astrophysics Data System (ADS)

    Trump, Jonathan R.; CANDELS, 3D-HST

    2016-01-01

    I will present the first robust measurement of black hole occupation over a wide range of host galaxy mass (8spatially resolved spectroscopy, which reliably distinguishes a nuclear AGN from extended star formation and largely avoids the star-formation dilution bias plaguing traditional low-mass AGN selection. The observations suggest bimodal seed formation: while many low-mass galaxies host massive black holes, their black hole occupation is ~10% that of massive galaxies. The measured black hole occupation qualitatively agrees with theoretical models of black hole formation, with massive direct-collapse seeds forming only in massive halos and black hole formation confined to lower-mass Pop III remnants in small halos.

  11. Electronic transport characterization of silicon wafers by spatially resolved steady-state photocarrier radiometric imaging

    SciTech Connect

    Wang, Qian; Li, Bincheng

    2015-09-28

    Spatially resolved steady-state photocarrier radiometric (PCR) imaging technique is developed to characterize the electronic transport properties of silicon wafers. Based on a nonlinear PCR theory, simulations are performed to investigate the effects of electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) on the steady-state PCR intensity profiles. The electronic transport parameters of an n-type silicon wafer are simultaneously determined by fitting the measured steady-state PCR intensity profiles to the three-dimensional nonlinear PCR model. The determined transport parameters are in good agreement with the results obtained by the conventional modulated PCR technique with multiple pump beam radii.

  12. Instrument for spatially resolved simultaneous measurements of forces and currents in particle beams

    NASA Astrophysics Data System (ADS)

    Spethmann, A.; Trottenberg, T.; Kersten, H.

    2015-01-01

    The article presents a device for spatially resolved and simultaneous measurements of forces and currents in particle beams, especially in beams composed of ions and neutral atoms. The forces are exerted by the impinging beam particles on a plane circular conductive target plate of 20 mm diameter mounted on a pendulum with electromagnetic force compensation. The force measurement in the micronewton range is achieved by electromagnetic compensation by means of static Helmholtz coils and permanent magnets attached to the pendulum. Exemplary measurements are performed in the 1.2 keV beam of a broad beam ion source. The simultaneous measurements of forces and currents onto the same target are compared with each other and with Faraday cup measurements.

  13. Instrument for spatially resolved simultaneous measurements of forces and currents in particle beams.

    PubMed

    Spethmann, A; Trottenberg, T; Kersten, H

    2015-01-01

    The article presents a device for spatially resolved and simultaneous measurements of forces and currents in particle beams, especially in beams composed of ions and neutral atoms. The forces are exerted by the impinging beam particles on a plane circular conductive target plate of 20 mm diameter mounted on a pendulum with electromagnetic force compensation. The force measurement in the micronewton range is achieved by electromagnetic compensation by means of static Helmholtz coils and permanent magnets attached to the pendulum. Exemplary measurements are performed in the 1.2 keV beam of a broad beam ion source. The simultaneous measurements of forces and currents onto the same target are compared with each other and with Faraday cup measurements. PMID:25638122

  14. Instrument for spatially resolved simultaneous measurements of forces and currents in particle beams

    SciTech Connect

    Spethmann, A. Trottenberg, T. Kersten, H.

    2015-01-15

    The article presents a device for spatially resolved and simultaneous measurements of forces and currents in particle beams, especially in beams composed of ions and neutral atoms. The forces are exerted by the impinging beam particles on a plane circular conductive target plate of 20 mm diameter mounted on a pendulum with electromagnetic force compensation. The force measurement in the micronewton range is achieved by electromagnetic compensation by means of static Helmholtz coils and permanent magnets attached to the pendulum. Exemplary measurements are performed in the 1.2 keV beam of a broad beam ion source. The simultaneous measurements of forces and currents onto the same target are compared with each other and with Faraday cup measurements.

  15. Spatially resolved methane band photometry of Saturn. II - Cloud structure models at four latitudes

    NASA Technical Reports Server (NTRS)

    West, R. A.

    1983-01-01

    Saturn's cloud vertical structures in the Equatorial Zone, South Equatorial Belt, and North and South Temperate Regions near + or - 30 deg latitudes are determined by means of an analysis of spatially resolved reflectivity measurements in the 6190, 7250, and 8996 A methane bands. Radiative transfer models are computed for a structure whose parameters are the methane column abundance in an aerosol-free layer at the top of the atmosphere, and the specific abundance of methane in a semiinfinite homogeneous gas-and-cloud mixture deep in the atmosphere. The structure for the South Equatorial Belt resembles that for the North Temperate Region. The level where unit cloud optical depth occurs in the South Temperate Region is deeper than the corresponding level at other latitudes. The differences between model parameters derived by means of different absorption bands are discussed.

  16. Dynamics of nanocubes embedding into polymer films investigated via spatially resolved plasmon modes.

    PubMed

    Bottomley, Adam; Prezgot, Daniel; Coyle, Jason P; Ianoul, Anatoli

    2016-06-01

    Integration of nanoparticles into thin films is essential for the development of functional materials, studies of fundamental interfacial processes, and exploitation of inherent properties from the particles themselves. In this work, we systematically investigate the process of incorporation of silver nanocubes into thin polystyrene films at temperatures just above the polymer glass transition. The process of nanocrystal incorporation can be precisely monitored via far-field spectroscopy to observe the response of spatially resolved hybrid plasmon modes. Each plasmon resonance has a distinct dynamic range and maximum sensitivity forming a complementary set of nanorulers that operates over a distance comparable to the edge length of the cubes. The approach explored in this work is a general robust method for the development of long-range polychromatic nanorulers. PMID:27180659

  17. Spatially resolved sub-Doppler overtone gain measurements on a small-scale supersonic HF laser

    NASA Astrophysics Data System (ADS)

    Wisniewski, Charles F.; Hewett, Kevin B.; Manke, Gerald C., II; Truman, C. Randall; Hager, Gordon D.

    2004-05-01

    The small signal gain of a small-scale HF overtone laser was measured using a sub-Doppler tunable diode laser system. Measurements of reactant concentration, flow velocity and gain length were also made. The spatially resolved, two-dimensional small signal gain and temperature maps that were generated show a highly inhomogeneous gain medium indicating the dominant role played by mixing of the H2 and F streams in HF laser performance. The measured gain and temperature data were analyzed with the aid of a two-dimensional computational fluid dynamics model. The results show that reactant mixing mechanisms have a large effect on the gain averaged over a vertical profile while kinetic rate mechanisms, including reaction rate constants and reactant concentration, have a greater effect on the maximum system gain.

  18. Noninvasive diagnostics of skin microphysical parameters based on spatially resolved diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Lisenko, S. A.; Kugeiko, M. M.

    2013-01-01

    The ability to determine noninvasively microphysical parameters (MPPs) of skin characteristic of malignant melanoma was demonstrated. The MPPs were the melanin content in dermis, saturation of tissue with blood vessels, and concentration and effective size of tissue scatterers. The proposed method was based on spatially resolved spectral measurements of skin diffuse reflectance and multiple regressions between linearly independent measurement components and skin MPPs. The regressions were established by modeling radiation transfer in skin with a wide variation of its MPPs. Errors in the determination of skin MPPs were estimated using fiber-optic measurements of its diffuse reflectance at wavelengths of commercially available semiconductor diode lasers (578, 625, 660, 760, and 806 nm) at source-detector separations of 0.23-1.38 mm.

  19. Muscle oxygenation during exercise under hypoxic conditions assessed by spatially resolved broadband NIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Geraskin, Dmitri; Platen, Petra; Franke, Julia; Andre, Christiane; Bloch, Wilhelm; Kohl-Bareis, Matthias

    2005-08-01

    Near-infrared spectroscopy (NIRS) is used for the non-invasive measurement of muscle oxygenation during an incremental cycle test in healthy volunteers. A broad band spatially resolved system is used that allows the reliability of current algorithms to be inspected with the main emphasis on tissue oxygen saturation (SO2) and oxygenated and deoxygenated haemoglobin concentrations. Physiological conditions were modulated by changing oxygen supply from normal (21 % O2 in inspired air) to conditions corresponding to 2000 and 4000 m altitude above sea level (15.4 and 11.9 % O2). Under these hypoxic conditions the decrease in SO2 with increased exercise power is highly correlated with the oxygen content of the inspired air. There is a clear correlation with physiological parameters (heart rate, pulse oxymetry, blood gas, lactate, spirometric data). Skin oxygenation parameters are compared to those of muscle.

  20. Growth-induced Stacking Faults of ZnO Nanorods Probed by Spatial Resolved Cathodoluminescence

    NASA Astrophysics Data System (ADS)

    Xie, Yong; Jie, Wan-Qi; Wang, Tao; Wiedenmann, Michael; Neuschl, Benjamin; Madel, Manfred; Wang, Ya-Bin; Feneberg, Martin; Thonke, Klaus

    2012-07-01

    Low density ZnO nanorods are grown by modified chemical vapor deposition on silicon substrates using gold as a catalyst. We use high resolution photoluminescence spectroscopy to gain the optical properties of these nanorods in large scale. The as-grown samples show sharp near-band-gap luminescence with a full width at half maximum of bound exciton peaks at about 300 μeV, and the ratio of ultraviolet/yellow luminescence larger than 100. Highly spatial and spectral resolved scanning electron microscope-cathodoluminescence is performed to excite the ZnO nanorods in single rods or different positions of single rods with the vapour-solid growth mechanism. The bottom of the nanorod has a 3.31-eV luminescence, which indicates that basal plane stacking faults are related to the defects that are created at the first stage of growth due to the misfit between ZnO and Si.

  1. Oblique-incidence spatially resolved diffuse reflectance spectroscopic diagnosis of skin cancer

    NASA Astrophysics Data System (ADS)

    Garcia-Uribe, Alejandro; Zou, Jun; Chang, Tzu-Hsuan; Duvic, Madeleine; Prieto, Victor; Wang, Lihong V.

    2010-02-01

    This paper presents the use of spatially resolved oblique-incidence diffuse reflectance spectroscopy for skin cancer diagnosis. Spatio-spectral data from 166 pigmented skin lesions were collected for the wavelength range from 455 to 765 nm. A set of neural network based classifiers separates the pigmented malignant melanomas from the benign and dysplastic subgroups. A total of 110 lesions were used as the training set and 56 lesions were used as the testing set. This classifier performs with an overall 100% sensitivity and 92% specificity for the training set and 100% sensitivity and 88% specificity for the testing set. The second classifier was designed to separate the benign from the dysplastic subgroups. For the second classifier a total of 100 lesions were used as the training set and 51 lesions were used as the testing set. The overall classification rates were 94% and 88% for the training and testing sets respectively.

  2. Estimating wide-angle, spatially varying reflectance using time-resolved inversion of backscattered light.

    PubMed

    Naik, Nikhil; Barsi, Christopher; Velten, Andreas; Raskar, Ramesh

    2014-05-01

    Imaging through complex media is a well-known challenge, as scattering distorts a signal and invalidates imaging equations. For coherent imaging, the input field can be reconstructed using phase conjugation or knowledge of the complex transmission matrix. However, for incoherent light, wave interference methods are limited to small viewing angles. On the other hand, time-resolved methods do not rely on signal or object phase correlations, making them suitable for reconstructing wide-angle, larger-scale objects. Previously, a time-resolved technique was demonstrated for uniformly reflecting objects. Here, we generalize the technique to reconstruct the spatially varying reflectance of shapes hidden by angle-dependent diffuse layers. The technique is a noninvasive method of imaging three-dimensional objects without relying on coherence. For a given diffuser, ultrafast measurements are used in a convex optimization program to reconstruct a wide-angle, three-dimensional reflectance function. The method has potential use for biological imaging and material characterization. PMID:24979627

  3. Dynamics of nanocubes embedding into polymer films investigated via spatially resolved plasmon modes

    NASA Astrophysics Data System (ADS)

    Bottomley, Adam; Prezgot, Daniel; Coyle, Jason P.; Ianoul, Anatoli

    2016-05-01

    Integration of nanoparticles into thin films is essential for the development of functional materials, studies of fundamental interfacial processes, and exploitation of inherent properties from the particles themselves. In this work, we systematically investigate the process of incorporation of silver nanocubes into thin polystyrene films at temperatures just above the polymer glass transition. The process of nanocrystal incorporation can be precisely monitored via far-field spectroscopy to observe the response of spatially resolved hybrid plasmon modes. Each plasmon resonance has a distinct dynamic range and maximum sensitivity forming a complementary set of nanorulers that operates over a distance comparable to the edge length of the cubes. The approach explored in this work is a general robust method for the development of long-range polychromatic nanorulers.Integration of nanoparticles into thin films is essential for the development of functional materials, studies of fundamental interfacial processes, and exploitation of inherent properties from the particles themselves. In this work, we systematically investigate the process of incorporation of silver nanocubes into thin polystyrene films at temperatures just above the polymer glass transition. The process of nanocrystal incorporation can be precisely monitored via far-field spectroscopy to observe the response of spatially resolved hybrid plasmon modes. Each plasmon resonance has a distinct dynamic range and maximum sensitivity forming a complementary set of nanorulers that operates over a distance comparable to the edge length of the cubes. The approach explored in this work is a general robust method for the development of long-range polychromatic nanorulers. Electronic supplementary information (ESI) available: Topographical evolution of a nanocube monolayer visualized by AFM, a plot of relative signal change vs. time, and an experimental schematic depicting a system with a high refractive index sub

  4. The Lyman break analogue Haro 11: spatially resolved chemodynamics with VLT FLAMES

    NASA Astrophysics Data System (ADS)

    James, B. L.; Tsamis, Y. G.; Walsh, J. R.; Barlow, M. J.; Westmoquette, M. S.

    2013-04-01

    Using VLT/Fibre Large Array Multi Element Spectrograph (FLAMES) optical integral field unit observations, we present the first spatially resolved spectroscopic study of the well-known blue compact galaxy Haro 11, thought to be a local analogue to high-redshift Lyman break galaxies. Haro 11 displays complex emission line profiles, consisting of narrow (full width at half-maximum, FWHM ≲ 200 km s-1) and broad (FWHM ˜ 200-300 km s-1) components. We identify three distinct emission knots kinematically connected to one another. A chemodynamical analysis is presented, revealing that spatially resolved ionic and elemental abundances do not agree with those derived from integrated spectra across the galaxy. We conclude that this is almost certainly due to the surface brightness weighting of electron temperature in integrated spectra, leading to higher derived abundances. We find that the eastern knot has a low gas density, but a higher temperature (by ˜4000 K) and consequently an oxygen abundance ˜0.4 dex lower than the neighbouring regions. A region of enhanced N/O is found specifically in Knot C, confirming previous studies that found anomalously high N/O ratios in this system. Maps of the Wolf-Rayet (WR) feature at 4686 Å reveal large WR populations (˜900-1500 stars) in Knots A and B. The lack of WR stars in Knot C combined with an age of ˜7.4 Myr suggests that a recently completed WR phase may be responsible for the observed N/O excess. Conversely, the absence of N-enriched gas and strong WR emission in Knots A and B suggests that we are observing these regions at an epoch where stellar ejecta has yet to cool and mix with the interstellar medium.

  5. Comparative study of photoreceptor and retinal ganglion cell topography and spatial resolving power in Dipsadidae snakes.

    PubMed

    Hauzman, Einat; Bonci, Daniela M O; Grotzner, Sonia R; Mela, Maritana; Liber, André M P; Martins, Sonia L; Ventura, Dora F

    2014-01-01

    The diurnal Dipsadidae snakes Philodryas olfersii and P. patagoniensis are closely related in their phylogeny but inhabit different ecological niches. P. olfersii is arboreal, whereas P. patagoniensis is preferentially terrestrial. The goal of the present study was to compare the density and topography of neurons, photoreceptors, and cells in the ganglion cell layer in the retinas of these two species using immunohistochemistry and Nissl staining procedures and estimate the spatial resolving power of their eyes based on the ganglion cell peak density. Four morphologically distinct types of cones were observed by scanning electron microscopy, 3 of which were labeled with anti-opsin antibodies: large single cones and double cones labeled by the antibody JH492 and small single cones labeled by the antibody JH455. The average densities of photoreceptors and neurons in the ganglion cell layer were similar in both species (∼10,000 and 7,000 cells·mm(-2), respectively). The estimated spatial resolving power was also similar, ranging from 2.4 to 2.7 cycles·degree(-1). However, the distribution of neurons had different specializations. In the arboreal P. olfersii, the isodensity maps had a horizontal visual streak, with a peak density in the central region and a lower density in the dorsal retina. This organization might be relevant for locomotion and hunting behavior in the arboreal layer. In the terrestrial P. patagoniensis, a concentric pattern of decreasing cell density emanated from an area centralis located in the naso-ventral retina. Lower densities were observed in the dorsal region. The ventrally high density improves the resolution in the superior visual field and may be an important adaptation for terrestrial snakes to perceive the approach of predators from above. PMID:25342570

  6. Direct Observation of Phase Transformations in Austenitic Stainless Steel Welds Using In-situ Spatially Resolved and Time-resolved X-ray Diffraction

    SciTech Connect

    Elmer, J.; Wong, J.; Ressler, T.

    1999-09-23

    Spatially resolved x-ray diffraction (SRXRD) and time resolved x-ray diffraction (TRXRD) were used to investigate real time solid state phase transformations and solidification in AISI type 304 stainless steel gas tungsten arc (GTA) welds. These experiments were conducted at Stanford Synchrotron Radiation Laboratory (SSRL) using a high flux beam line. Spatially resolved observations of {gamma} {leftrightarrow} {delta} solid state phase transformations were performed in the heat affected zone (HAZ) of moving welds and time-resolved observations of the solidification sequence were performed in the fusion zone (FZ) of stationary welds after the arc had been terminated. Results of the moving weld experiments showed that the kinetics of the {gamma}{yields}{delta} phase transformation on heating in the HAZ were sufficiently rapid to transform a narrow region surrounding the liquid weld pool to the {delta} ferrite phase. Results of the stationary weld experiments showed, for the first time, that solidification can occur directly to the {delta} ferrite phase, which persisted as a single phase for 0.5s. Upon solidification to {delta}, the {delta} {yields} {gamma} phase transformation followed and completed in 0.2s as the weld cooled further to room temperature.

  7. Method for depth-resolved quantitation of optical properties in layered media using spatially modulated quantitative spectroscopy

    PubMed Central

    Saager, Rolf B.; Truong, Alex; Cuccia, David J.; Durkin, Anthony J.

    2011-01-01

    We have demonstrated that spatially modulated quantitative spectroscopy (SMoQS) is capable of extracting absolute optical properties from homogeneous tissue simulating phantoms that span both the visible and near-infrared wavelength regimes. However, biological tissue, such as skin, is highly structured, presenting challenges to quantitative spectroscopic techniques based on homogeneous models. In order to more accurately address the challenges associated with skin, we present a method for depth-resolved optical property quantitation based on a two layer model. Layered Monte Carlo simulations and layered tissue simulating phantoms are used to determine the efficacy and accuracy of SMoQS to quantify layer specific optical properties of layered media. Initial results from both the simulation and experiment show that this empirical method is capable of determining top layer thickness within tens of microns across a physiological range for skin. Layer specific chromophore concentration can be determined to <±10% the actual values, on average, whereas bulk quantitation in either visible or near infrared spectroscopic regimes significantly underestimates the layer specific chromophore concentration and can be confounded by top layer thickness. PMID:21806282

  8. Spatially and momentum resolved energy electron loss spectra from an ultra-thin PrNiO{sub 3} layer

    SciTech Connect

    Kinyanjui, M. K. Kaiser, U.; Benner, G.; Pavia, G.; Boucher, F.; Habermeier, H.-U.; Keimer, B.

    2015-05-18

    We present an experimental approach which allows for the acquisition of spectra from ultra-thin films at high spatial, momentum, and energy resolutions. Spatially and momentum (q) resolved electron energy loss spectra have been obtained from a 12 nm ultra-thin PrNiO{sub 3} layer using a nano-beam electron diffraction based approach which enabled the acquisition of momentum resolved spectra from individual, differently oriented nano-domains and at different positions of the PrNiO{sub 3} thin layer. The spatial and wavelength dependence of the spectral excitations are obtained and characterized after the analysis of the experimental spectra using calculated dielectric and energy loss functions. The presented approach makes a contribution towards obtaining momentum-resolved spectra from nanostructures, thin film, heterostructures, surfaces, and interfaces.

  9. Investigation of microstructure in additive manufactured Inconel 625 by spatially resolved neutron transmission spectroscopy

    DOE PAGESBeta

    Tremsin, Anton S.; Gao, Yan; Dial, Laura C.; Grazzi, Francesco; Shinohara, Takenao

    2016-07-08

    Non-destructive testing techniques based on neutron imaging and diffraction can provide information on the internal structure of relatively thick metal samples (up to several cm), which are opaque to other conventional non-destructive methods. Spatially resolved neutron transmission spectroscopy is an extension of traditional neutron radiography, where multiple images are acquired simultaneously, each corresponding to a narrow range of energy. The analysis of transmission spectra enables studies of bulk microstructures at the spatial resolution comparable to the detector pixel. In this study we demonstrate the possibility of imaging (with ~100 μm resolution) distribution of some microstructure properties, such as residual strain,more » texture, voids and impurities in Inconel 625 samples manufactured with an additive manufacturing method called direct metal laser melting (DMLM). Although this imaging technique can be implemented only in a few large-scale facilities, it can be a valuable tool for optimization of additive manufacturing techniques and materials and for correlating bulk microstructure properties to manufacturing process parameters. Additionally, the experimental strain distribution can help validate finite element models which many industries use to predict the residual stress distributions in additive manufactured components.« less

  10. Analyzing Spatially Resolved Z-pinch Spectra to Determine the Nature of ``Bright Spots''*

    NASA Astrophysics Data System (ADS)

    Apruzese, J. P.; Giuliani, J. L.; Thornhill, J. W.; Ampleford, D. J.; Jones, B.; Coverdale, C. A.

    2011-10-01

    Wire array Z-pinch implosions which access the K-shell stages of their load elements are usually characterized by spatially nonuniform emission. But, is the existence of the ``bright spots'' due to density enhancement, higher temperature, or some combination of the two? Does the answer vary with atomic number of the load? To investigate this issue we have analyzed spatially resolved spectra from Cu and Al pinches driven by the Z generator. Correlation studies and regression analyses from the derived conditions are employed in order to infer the cause(s) of the local enhancements of K-shell powers. Work supported by U. S. Department of Energy, National Nuclear Security Administration. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's NNSA under contract DE-AC04-94AL85000. JPA is a consultant to NRL through L3 Communications, Chantilly, VA 20151.

  11. Spatially resolved TiOx phases in switched RRAM devices using soft X-ray spectromicroscopy

    PubMed Central

    Carta, D.; Hitchcock, A. P.; Guttmann, P.; Regoutz, A.; Khiat, A.; Serb, A.; Gupta, I.; Prodromakis, T.

    2016-01-01

    Reduction in metal-oxide thin films has been suggested as the key mechanism responsible for forming conductive phases within solid-state memory devices, enabling their resistive switching capacity. The quantitative spatial identification of such conductive regions is a daunting task, particularly for metal-oxides capable of exhibiting multiple phases as in the case of TiOx. Here, we spatially resolve and chemically characterize distinct TiOx phases in localized regions of a TiOx–based memristive device by combining full-field transmission X-ray microscopy with soft X-ray spectroscopic analysis that is performed on lamella samples. We particularly show that electrically pre-switched devices in low-resistive states comprise reduced disordered phases with O/Ti ratios around 1.37 that aggregate in a ~100 nm highly localized region electrically conducting the top and bottom electrodes of the devices. We have also identified crystalline rutile and orthorhombic-like TiO2 phases in the region adjacent to the main reduced area, suggesting that the temperature increases locally up to 1000 K, validating the role of Joule heating in resistive switching. Contrary to previous studies, our approach enables to simultaneously investigate morphological and chemical changes in a quantitative manner without incurring difficulties imposed by interpretation of electron diffraction patterns acquired via conventional electron microscopy techniques. PMID:26891776

  12. Spatially resolved Brillouin spectroscopy for in vivo determination of the biomechanical properties of the crystalline lenses

    NASA Astrophysics Data System (ADS)

    Stachs, Oliver; Reiß, Stephan; Guthoff, Rudolf; Stolz, Heinrich

    2012-03-01

    Confocal Brillouin spectroscopy is an innovative measurement method for the noninvasive determination of rheological tissue properties. Its application in ophthalmology can offer the possibility to determine in vivo the deformation properties of eye lens with spatial resolution. This seems to be a promising approach concerning current presbyopia research. Due to the spatially resolved detection of the viscoelastic lens properties, a better understanding of the natural aging process of the lens and the influences of different lens opacities on the stiffness is expected. Based on spectral data the refractive index profile, the protein concentration and the density profile within the lens tissue can be derived. A measurement set-up for confocal Brillouin microscopy based on spectral analysis of spontaneous Brillouin scattering signals by using a high-resolution dispersive device is presented. First in vivo measurements results on rabbit eyes are presented and evaluated concerning refractive index distribution, protein concentration, density and rheological significance. These data are compared with known research results of ex vivo lenses.

  13. Spatially resolved proteomic mapping in living cells with the engineered peroxidase APEX2

    PubMed Central

    Hung, Victoria; Udeshi, Namrata D; Lam, Stephanie S; Loh, Ken H; Cox, Kurt J; Pedram, Kayvon; Carr, Steven A; Ting, Alice Y

    2016-01-01

    This protocol describes a method to obtain spatially resolved proteomic maps of specific compartments within living mammalian cells. An engineered peroxidase, APEX2, is genetically targeted to a cellular region of interest. Upon the addition of hydrogen peroxide for 1 min to cells preloaded with a biotin-phenol substrate, APEX2 generates biotin-phenoxyl radicals that covalently tag proximal endogenous proteins. Cells are then lysed, and biotinylated proteins are enriched with streptavidin beads and identified by mass spectrometry. We describe the generation of an appropriate APEX2 fusion construct, proteomic sample preparation, and mass spectrometric data acquisition and analysis. A two-state stable isotope labeling by amino acids in cell culture (SILAC) protocol is used for proteomic mapping of membrane-enclosed cellular compartments from which APEX2-generated biotin-phenoxyl radicals cannot escape. For mapping of open cellular regions, we instead use a ‘ratiometric’ three-state SILAC protocol for high spatial specificity. Isotopic labeling of proteins takes 5–7 cell doublings. Generation of the biotinylated proteomic sample takes 1 d, acquiring the mass spectrometric data takes 2–5 d and analysis of the data to obtain the final proteomic list takes 1 week. PMID:26866790

  14. A reflective image-rotating periscope for spatially resolved Thomson-scattering experiments on OMEGA

    NASA Astrophysics Data System (ADS)

    Katz, J.; Ross, J. S.; Sorce, C.; Froula, D. H.

    2013-12-01

    A reflective image rotating periscope has been deployed on the Thomson-scattering system at the Laboratory for Laser Energetics, enabling the capability to make spatially resolved measurements of plasma conditions using either the 2ω (527-nm) or 4ω (263-nm) probe beam. The spectral content of ion-acoustic and electron plasma wave Thomson-scattering features are analyzed along the probe beam's axis of propagation using a pair of imaging Czerny-Turner spectrometers. A method for calculating image rotation was applied to design a translating periscope mirror assembly that provides fine adjustment of the image orientation at the spectrometer input plane. Spectrally dispersed Thomson-scattering signals are recorded using time-gated intensified charge-coupled-device cameras. Spectral resolution of up to 0.03 nm (0.2 nm) is achieved using a 1-m (0.3-m) spectrometer, allowing for simultaneous measurements of the ion-acoustic and electron plasma wave features. The optical system's 20-μm imaging resolution provides excellent noise rejection and spatial definition of the Thomson-scattering volume.

  15. A microreactor array for spatially resolved measurement of catalytic activity for high-throughput catalysis science

    SciTech Connect

    Kondratyuk, Petro; Gumuslu, Gamze; Shukla, Shantanu; Miller, James B; Morreale, Bryan D; Gellman, Andrew J

    2013-04-01

    We describe a 100 channel microreactor array capable of spatially resolved measurement of catalytic activity across the surface of a flat substrate. When used in conjunction with a composition spread alloy film (CSAF, e.g. Pd{sub x}Cu{sub y}Au{sub 1-x-y}) across which component concentrations vary smoothly, such measurements permit high-throughput analysis of catalytic activity and selectivity as a function of catalyst composition. In the reported implementation, the system achieves spatial resolution of 1 mm{sup 2} over a 10×10 mm{sup 2} area. During operation, the reactant gases are delivered at constant flow rate to 100 points of differing composition on the CSAF surface by means of a 100-channel microfluidic device. After coming into contact with the CSAF catalyst surface, the product gas mixture from each of the 100 points is withdrawn separately through a set of 100 isolated channels for analysis using a mass spectrometer. We demonstrate the operation of the device on a Pd{sub x}Cu{sub y}Au{sub 1-x-y} CSAF catalyzing the H{sub 2}-D{sub 2} exchange reaction at 333 K. In essentially a single experiment, we measured the catalytic activity over a broad swathe of concentrations from the ternary composition space of the Pd{sub x}Cu{sub y}Au{sub 1-x-y} alloy.

  16. Spatially resolved spectroscopic measurements of a dielectric barrier discharge plasma jet applicable for soft ionization

    NASA Astrophysics Data System (ADS)

    Olenici-Craciunescu, S. B.; Müller, S.; Michels, A.; Horvatic, V.; Vadla, C.; Franzke, J.

    2011-03-01

    An atmospheric pressure microplasma ionization source based on a dielectric barrier discharge with a helium plasma cone outside the electrode region has been developed for liquid chromatography/mass spectrometry and as ionization source for ion mobility spectrometry. It turned out that dielectric barrier discharge ionization could be regarded as a soft ionization technique characterized by only minor fragmentation similar to atmospheric pressure chemical ionization (APCI). Mainly protonated molecules were detected. In order to characterize the soft ionization mechanism spatially resolved optical emission spectrometry (OES) measurements were performed on plasma jets burning either in He or in Ar. Besides to spatial intensity distributions of noble gas spectral lines, in both cases a special attention was paid to lines of N 2+ and N 2. The obtained mapping of the plasma jet shows very different number density distributions of relevant excited species. In the case of helium plasma jet, strong N 2+ lines were observed. In contrast to that, the intensities of N 2 lines in Ar were below the present detection limit. The positions of N 2+ and N 2 distribution maxima in helium indicate the regions where the highest efficiency of the water ionization and the protonation process is expected.

  17. A split imaging spectrometer for temporally and spatially resolved titanium absorption spectroscopy

    SciTech Connect

    Hager, J. D. Lanier, N. E.; Kline, J. L.; Flippo, K. A.; Bruns, H. C.; Schneider, M.; Saculla, M.; McCarville, T.

    2014-11-15

    We present a temporally and a spatially resolved spectrometer for titanium x-ray absorption spectroscopy along 2 axial symmetric lines-of-sight. Each line-of-sight of the instrument uses an elliptical crystal to acquire both the 2p and 3p Ti absorption lines on a single, time gated channel of the instrument. The 2 axial symmetric lines-of-sight allow the 2p and 3p absorption features to be measured through the same point in space using both channels of the instrument. The spatially dependent material temperature can be inferred by observing the 2p and the 3p Ti absorption features. The data are recorded on a two strip framing camera with each strip collecting data from a single line-of-sight. The design is compatible for use at both the OMEGA laser and the National Ignition Facility. The spectrometer is intended to measure the material temperature behind a Marshak wave in a radiatively driven SiO{sub 2} foam with a Ti foam tracer. In this configuration, a broad band CsI backlighter will be used for a source and the Ti absorption spectrum measured.

  18. Spatially resolved proteomic mapping in living cells with the engineered peroxidase APEX2.

    PubMed

    Hung, Victoria; Udeshi, Namrata D; Lam, Stephanie S; Loh, Ken H; Cox, Kurt J; Pedram, Kayvon; Carr, Steven A; Ting, Alice Y

    2016-03-01

    This protocol describes a method to obtain spatially resolved proteomic maps of specific compartments within living mammalian cells. An engineered peroxidase, APEX2, is genetically targeted to a cellular region of interest. Upon the addition of hydrogen peroxide for 1 min to cells preloaded with a biotin-phenol substrate, APEX2 generates biotin-phenoxyl radicals that covalently tag proximal endogenous proteins. Cells are then lysed, and biotinylated proteins are enriched with streptavidin beads and identified by mass spectrometry. We describe the generation of an appropriate APEX2 fusion construct, proteomic sample preparation, and mass spectrometric data acquisition and analysis. A two-state stable isotope labeling by amino acids in cell culture (SILAC) protocol is used for proteomic mapping of membrane-enclosed cellular compartments from which APEX2-generated biotin-phenoxyl radicals cannot escape. For mapping of open cellular regions, we instead use a 'ratiometric' three-state SILAC protocol for high spatial specificity. Isotopic labeling of proteins takes 5-7 cell doublings. Generation of the biotinylated proteomic sample takes 1 d, acquiring the mass spectrometric data takes 2-5 d and analysis of the data to obtain the final proteomic list takes 1 week. PMID:26866790

  19. Spatially-Resolved Modeling of Spin and Valley Hall Effects in Two-Dimensional Semiconductors

    NASA Astrophysics Data System (ADS)

    Lenferink, E. J.; Jia, Y.; Stern, N. P.

    2015-03-01

    In monolayers of transition metal dichalcogenides (1L-TMDs), a valley degree of freedom emerges for charge carriers due to the absence of spatial inversion symmetry. Strong spin-orbit interaction couples spin and valley, resulting in correlated spin, valley, and charge transport such as transverse Hall effects. Spatially-resolved measurements of these Hall effects have recently been achieved in monolayer MoS2, necessitating a detailed picture for understanding transport and relaxation mechanisms in 1L-TMDs that considers carrier, valley, and spin motion and generation processes. Here, we study spin and valley Hall effects in 1L-TMD devices by simulating the transport of spin- and valley-polarized carriers with a generalized drift diffusion model incorporating circularly polarized optical excitation. Spin and valley accumulation and the transverse voltage are analyzed in different device geometries. We compare the electron and hole contributions to the transverse voltage and discuss the potential for a measurement of the valley relaxation times of free carriers in 1L-TMDs. This work was supported by the Institute for Sustainability and Energy at Northwestern and the U.S. Department of Energy (DE-SC0012130). N.P.S. acknowledges support as an Alfred P. Sloan Research Fellow.

  20. Spatially resolved TiOx phases in switched RRAM devices using soft X-ray spectromicroscopy

    NASA Astrophysics Data System (ADS)

    Carta, D.; Hitchcock, A. P.; Guttmann, P.; Regoutz, A.; Khiat, A.; Serb, A.; Gupta, I.; Prodromakis, T.

    2016-02-01

    Reduction in metal-oxide thin films has been suggested as the key mechanism responsible for forming conductive phases within solid-state memory devices, enabling their resistive switching capacity. The quantitative spatial identification of such conductive regions is a daunting task, particularly for metal-oxides capable of exhibiting multiple phases as in the case of TiOx. Here, we spatially resolve and chemically characterize distinct TiOx phases in localized regions of a TiOx-based memristive device by combining full-field transmission X-ray microscopy with soft X-ray spectroscopic analysis that is performed on lamella samples. We particularly show that electrically pre-switched devices in low-resistive states comprise reduced disordered phases with O/Ti ratios around 1.37 that aggregate in a ~100 nm highly localized region electrically conducting the top and bottom electrodes of the devices. We have also identified crystalline rutile and orthorhombic-like TiO2 phases in the region adjacent to the main reduced area, suggesting that the temperature increases locally up to 1000 K, validating the role of Joule heating in resistive switching. Contrary to previous studies, our approach enables to simultaneously investigate morphological and chemical changes in a quantitative manner without incurring difficulties imposed by interpretation of electron diffraction patterns acquired via conventional electron microscopy techniques.

  1. Spatially resolved TiOx phases in switched RRAM devices using soft X-ray spectromicroscopy.

    PubMed

    Carta, D; Hitchcock, A P; Guttmann, P; Regoutz, A; Khiat, A; Serb, A; Gupta, I; Prodromakis, T

    2016-01-01

    Reduction in metal-oxide thin films has been suggested as the key mechanism responsible for forming conductive phases within solid-state memory devices, enabling their resistive switching capacity. The quantitative spatial identification of such conductive regions is a daunting task, particularly for metal-oxides capable of exhibiting multiple phases as in the case of TiOx. Here, we spatially resolve and chemically characterize distinct TiOx phases in localized regions of a TiOx-based memristive device by combining full-field transmission X-ray microscopy with soft X-ray spectroscopic analysis that is performed on lamella samples. We particularly show that electrically pre-switched devices in low-resistive states comprise reduced disordered phases with O/Ti ratios around 1.37 that aggregate in a ~100 nm highly localized region electrically conducting the top and bottom electrodes of the devices. We have also identified crystalline rutile and orthorhombic-like TiO2 phases in the region adjacent to the main reduced area, suggesting that the temperature increases locally up to 1000 K, validating the role of Joule heating in resistive switching. Contrary to previous studies, our approach enables to simultaneously investigate morphological and chemical changes in a quantitative manner without incurring difficulties imposed by interpretation of electron diffraction patterns acquired via conventional electron microscopy techniques. PMID:26891776

  2. A split imaging spectrometer for temporally and spatially resolved titanium absorption spectroscopy.

    PubMed

    Hager, J D; Lanier, N E; Kline, J L; Flippo, K A; Bruns, H C; Schneider, M; Saculla, M; McCarville, T

    2014-11-01

    We present a temporally and a spatially resolved spectrometer for titanium x-ray absorption spectroscopy along 2 axial symmetric lines-of-sight. Each line-of-sight of the instrument uses an elliptical crystal to acquire both the 2p and 3p Ti absorption lines on a single, time gated channel of the instrument. The 2 axial symmetric lines-of-sight allow the 2p and 3p absorption features to be measured through the same point in space using both channels of the instrument. The spatially dependent material temperature can be inferred by observing the 2p and the 3p Ti absorption features. The data are recorded on a two strip framing camera with each strip collecting data from a single line-of-sight. The design is compatible for use at both the OMEGA laser and the National Ignition Facility. The spectrometer is intended to measure the material temperature behind a Marshak wave in a radiatively driven SiO2 foam with a Ti foam tracer. In this configuration, a broad band CsI backlighter will be used for a source and the Ti absorption spectrum measured. PMID:25430177

  3. In situ distributed diagnostics of flowable electrode systems: resolving spatial and temporal limitations.

    PubMed

    Dennison, C R; Gogotsi, Y; Kumbur, E C

    2014-09-14

    In this study, we have developed an in situ distributed diagnostics tool to investigate spatial and temporal effects in electrochemical systems based on flowable electrodes. Specifically, an experimental approach was developed that enables spatially-resolved voltage measurements to be obtained in situ, in real-time. To extract additional data from these distributed measurements, an experimentally-parameterized equivalent circuit model with a new 'flow capacitor' circuit element was developed to predict the distributions of various system parameters during operation. As a case study, this approach was applied to investigate the behavior of the suspension electrodes used in an electrochemical flow capacitor under flowing and static conditions. The volumetric capacitance is reduced from 15.6 F ml(-1) to 1.1 F ml(-1) under flowing conditions. Results indicate that the majority of the charging in suspension electrodes occurs within ∼750 μm of the current collectors during flow, which gives rise to significant state-of-charge gradients across the cell, as well as underutilization of the available active material. The underlying cause of this observation is attributed to the relatively high electrical resistance of the slurry coupled with a stratified charging regime and insufficient residence time. The observations highlight the need to develop more conductive slurries and to design cells with reduced charge transport lengths. PMID:25055763

  4. Direct asymmetry measurement of temperature and density spatial distributions in inertial confinement fusion plasmas from pinhole space-resolved spectra

    SciTech Connect

    Nagayama, T.; Mancini, R. C.; Florido, R.; Mayes, D.; Tommasini, R.; Koch, J. A.; Delettrez, J. A.; Regan, S. P.; Smalyuk, V. A.

    2014-05-15

    Two-dimensional space-resolved temperature and density images of an inertial confinement fusion (ICF) implosion core have been diagnosed for the first time. Argon-doped, direct-drive ICF experiments were performed at the Omega Laser Facility and a collection of two-dimensional space-resolved spectra were obtained from an array of gated, spectrally resolved pinhole images recorded by a multi-monochromatic x-ray imager. Detailed spectral analysis revealed asymmetries of the core not just in shape and size but in the temperature and density spatial distributions, thus characterizing the core with an unprecedented level of detail.

  5. A study of the stellar populations of M32 based on its spatially resolved spectrum

    NASA Astrophysics Data System (ADS)

    Hardy, Eduardo; Couture, Jean; Couture, Christian; Joncas, Gilles

    1994-01-01

    We present new spatially resolved spectroscopic observations of M32 in the 4000-6800 A spectral interval within a radial range of about 2re. These observations breach the gap between the center of M32 and the outer regions which have recently been resolved into stars. Using Bica and Alloin's spectral library we show by simple comparison that no globular cluster energy distribution matches the mean observed spectrum for any metallicity at any radial position. We then show that the addition of intermediate age populations allows an optimized solution that fits well the galaxy spectra. The conclusion that M32 is not an old single-age system akin to an overgrown globular cluster, nor a combination of such, is then inescapable in agreement with recent studies of its color-magnitude diagram. Next we use Pickles stellar library to obtain optimized solutions as function of position and thus evaluate the radial variation of age and metallicity. We find a well defined metallicity gradient Delta(Fe/H)/Delta log(r) = -0.25 +/- 0.07, for r greater than or = 15 sec (i.e., 50 pc), which is similar to that of giant ellipticals. But we find no evidence for a significant variation in the Fe/Mg ratio, or of age, with radius. We confirm the existence of radial gradients of individual spectral features and find, for the first time, a radial gradient of the Mg2 feature. The latter translates into a metallicity gradient compatible with the one we derive from spectral synthesis. The central region within r approximately 50 pc is peculiar in that most gradients appear only beyond this radial distance.

  6. Deep Hubble Space Telescope Imaging of Sextans A. I. The Spatially Resolved Recent Star Formation History

    NASA Astrophysics Data System (ADS)

    Dohm-Palmer, Robbie C.; Skillman, Evan D.; Mateo, Mario; Saha, Abi; Dolphin, Andrew; Tolstoy, Eline; Gallagher, Jay S.; Cole, Andrew A.

    2002-02-01

    We have measured stellar photometry from deep Cycle 7 Hubble Space Telescope/WFPC2 imaging of the dwarf irregular galaxy Sextans A. The imaging was taken in three filters: F555W (V; eight orbits), F814W (I; 16 orbits), and F656N (Hα one orbit). Combining these data with Cycle 5 WFPC2 observations provides nearly complete coverage of the optically visible portion of the galaxy. The Cycle 7 observations are nearly 2 mag more sensitive than the Cycle 5 observations, which provides unambiguous separation of the faint blue helium-burning stars (BHeB stars) from contaminant populations. The depth of the photometry allows us to compare recent star formation histories recovered from both the main-sequence stars and the BHeB stars for the last 300 Myr. The excellent agreement between these independent star formation rate (SFR) calculations is a resounding confirmation for the legitimacy of using the BHeB stars to calculate the recent SFR. Using the BHeB stars we have calculated the global star formation history over the past 700 Myr. The history calculated from the Cycle 7 data is remarkably identical to that calculated from the Cycle 5 data, implying that both halves of the galaxy formed stars in concert. We have also calculated the spatially resolved star formation history, combining the fields from the Cycle 5 and Cycle 7 data. The star-forming regions are found in three major zones of the galaxy. One of these zones is extremely young, consisting of only a single star-forming region that is less than 20 Myr old. Two of these zones are associated with high column density neutral gas, while the third, and oldest, is not. Our interpretation of this pattern of star formation is that it is an orderly stochastic process. Star formation begins on the edge of a gas structure and progressively eats away at the cloud, breaking it up and inducing further star formation. A more quantitative analysis of the star formation process must await a larger sample of galaxies with spatially

  7. SDSS IV MaNGA - Spatially resolved diagnostic diagrams: A proof that many galaxies are LIERs

    NASA Astrophysics Data System (ADS)

    Belfiore, Francesco; Maiolino, Roberto; Maraston, Claudia; Emsellem, Eric; Bershady, Matthew A.; Masters, Karen L.; Yan, Renbin; Bizyaev, Dmitry; Boquien, Médéric; Brownstein, Joel R.; Bundy, Kevin; Drory, Niv; Heckman, Timothy M.; Law, David R.; Roman-Lopes, Alexandre; Pan, Kaike; Stanghellini, Letizia; Thomas, Daniel; Weijmans, Anne-Marie; Westfall, Kyle B.

    2016-05-01

    We study the spatially resolved excitation properties of the ionised gas in a sample of 646 galaxies using integral field spectroscopy data from SDSS-IV MaNGA. Making use of Baldwin-Philips-Terlevich diagnostic diagrams we demonstrate the ubiquitous presence of extended (kpc scale) low ionisation emission-line regions (LIERs) in both star forming and quiescent galaxies. In star forming galaxies LIER emission can be associated with diffuse ionised gas, most evident as extra-planar emission in edge-on systems. In addition, we identify two main classes of galaxies displaying LIER emission: `central LIER' (cLIER) galaxies, where central LIER emission is spatially extended, but accompanied by star formation at larger galactocentric distances, and `extended LIER' (eLIER) galaxies, where LIER emission is extended throughout the whole galaxy. In eLIER and cLIER galaxies, LIER emission is associated with radially flat, low Hα equivalent width of line emission (< 3 Å) and stellar population indices demonstrating the lack of young stellar populations, implying that line emission follows tightly the continuum due to the underlying old stellar population. The Hα surface brightness radial profiles are always shallower than 1/r2 and the line ratio [OIII]λ5007/[OII]λ3727,29 (a tracer of the ionisation parameter of the gas) shows a flat gradient. This combined evidence strongly supports the scenario in which LIER emission is not due to a central point source but to diffuse stellar sources, the most likely candidates being hot, evolved (post-asymptotic giant branch) stars. Shocks are observed to play a significant role in the ionisation of the gas only in rare merging and interacting systems.

  8. Spatially resolved characterization of biogenic manganese oxideproduction within a bacterial biofilm

    SciTech Connect

    Toner, Brandy; Fakra, Sirine; Villalobos, Mario; Warwick, Tony; Sposito, Garrison

    2004-10-01

    Pseudomonas putida strain MnB1, a biofilm forming bacteria, was used as a model for the study of bacterial Mn oxidation in freshwater and soil environments. The oxidation of Mn{sub (aq)}{sup +2} by P. putida was characterized by spatially and temporally resolving the oxidation state of Mn in the presence of a bacterial biofilm using scanning transmission x-ray microscopy (STXM) combined with near edge x-ray absorption fine structure (NEXAFS) spectroscopy at the Mn-L{sub 2,3} absorption edges. Subsamples were collected from growth flasks containing 0.1 mM and 1 mM total Mn at 16, 24, 36 and 48 hours after inoculation. Immediately after collection, the unprocessed hydrated subsamples were imaged at 40 nm resolution. Manganese NEXAFS spectra were extracted from x-ray energy sequences of STXM images (stacks) and fit with linear combinations of well characterized reference spectra to obtain quantitative relative abundances of Mn(II), Mn(III) and Mn(IV). Careful consideration was given to uncertainty in the normalization of the reference spectra, choice of reference compounds, and chemical changes due to radiation damage. The STXM results confirm that Mn{sub (aq)}{sup +2} was removed from solution by P. putida and was concentrated as Mn(III) and Mn(IV) immediately adjacent to the bacterial cells. The Mn precipitates were completely enveloped by bacterial biofilm material. The distribution of Mn oxidation states was spatially heterogeneous within and between the clusters of bacterial cells. Scanning transmission x-ray microscopy is a promising tool to advance the study of hydrated interfaces between minerals and bacteria, particularly in cases where the structure of bacterial biofilms needs to be maintained.

  9. EMCCD based luminescence imaging system for spatially resolved geo-chronometric and radiation dosimetric applications

    NASA Astrophysics Data System (ADS)

    Chauhan, N.; Adhyaru, P.; Vaghela, H.; Singhvi, A. K.

    2014-11-01

    We report the development of an Electron Multiplier Charge Coupled Device (EMCCD) based luminescence dating system. The system enables position sensitive measurements of luminescence for the estimation of spatially resolved distribution of equivalent dose for complex geological samples. The system includes: 1) a sample stimulation unit (with both thermal and optical stimulations), 2) an optics unit that comprises imaging optics and, 3) a data acquisition and processing unit. The system works in a LabVIEW environment with a graphical user interface (GUI). User specified stimulation protocols enable thermal and optical stimulation in any desired combination. The optics unit images the luminescence on to a EMCCD (512 × 512 pixels, each of 16μm × 16μm size) and maintains a unit magnification. This unit has flexible focusing and a filter housing that enables change of filters combinations without disturbing the setup. Time integrated EMCCD images of luminescence from the sample are acquired as a function of programmable dwell time and these images are processed using indigenously developed MATLAB based programs. Additionally, the programs align the acquired images using a set of control points (identifier features on the images) to a single pixel accuracy. The dose evaluation is based on integrated intensity from selected pixels followed by generation of a growth curve giving luminescence as a function of applied beta doses. Development of this EMCCD camera based luminescence system will enable in-situ luminescence measurements of the samples, without the requirement of separating mineral grains from their matrix. It will also allow age estimation of samples such as lithic artifacts/structures via dating of their surfaces, fusion crust of meteorites, pedogenic carbonates, etc and will additionally open up possibilities of application like testing spatial uniformity of doping in artificial luminescence phosphors, dating/dosimetry of inclusions etc.

  10. A SCR Model Calibration Approach with Spatially Resolved Measurements and NH3 Storage Distributions

    DOE PAGESBeta

    Song, Xiaobo; Parker, Gordon G.; Johnson, John H.; Naber, Jeffrey D.; Pihl, Josh A.

    2014-11-27

    The selective catalytic reduction (SCR) is a technology used for reducing NO x emissions in the heavy-duty diesel (HDD) engine exhaust. In this study, the spatially resolved capillary inlet infrared spectroscopy (Spaci-IR) technique was used to study the gas concentration and NH3 storage distributions in a SCR catalyst, and to provide data for developing a SCR model to analyze the axial gaseous concentration and axial distributions of NH3 storage. A two-site SCR model is described for simulating the reaction mechanisms. The model equations and a calculation method was developed using the Spaci-IR measurements to determine the NH3 storage capacity andmore » the relationships between certain kinetic parameters of the model. Moreover, a calibration approach was then applied for tuning the kinetic parameters using the spatial gaseous measurements and calculated NH3 storage as a function of axial position instead of inlet and outlet gaseous concentrations of NO, NO2, and NH3. The equations and the approach for determining the NH3 storage capacity of the catalyst and a method of dividing the NH3 storage capacity between the two storage sites are presented. It was determined that the kinetic parameters of the adsorption and desorption reactions have to follow certain relationships for the model to simulate the experimental data. Finally, the modeling results served as a basis for developing full model calibrations to SCR lab reactor and engine data and state estimator development as described in the references (Song et al. 2013a, b; Surenahalli et al. 2013).« less

  11. Constructing a Spatially Resolved Methane Emission Inventory for the Barnett Shale Region.

    PubMed

    Lyon, David R; Zavala-Araiza, Daniel; Alvarez, Ramón A; Harriss, Robert; Palacios, Virginia; Lan, Xin; Talbot, Robert; Lavoie, Tegan; Shepson, Paul; Yacovitch, Tara I; Herndon, Scott C; Marchese, Anthony J; Zimmerle, Daniel; Robinson, Allen L; Hamburg, Steven P

    2015-07-01

    Methane emissions from the oil and gas industry (O&G) and other sources in the Barnett Shale region were estimated by constructing a spatially resolved emission inventory. Eighteen source categories were estimated using multiple data sets, including new empirical measurements at regional O&G sites and a national study of gathering and processing facilities. Spatially referenced activity data were compiled from federal and state databases and combined with O&G facility emission factors calculated using Monte Carlo simulations that account for high emission sites representing the very upper portion, or fat-tail, in the observed emissions distributions. Total methane emissions in the 25-county Barnett Shale region in October 2013 were estimated to be 72,300 (63,400-82,400) kg CH4 h(-1). O&G emissions were estimated to be 46,200 (40,000-54,100) kg CH4 h(-1) with 19% of emissions from fat-tail sites representing less than 2% of sites. Our estimate of O&G emissions in the Barnett Shale region was higher than alternative inventories based on the United States Environmental Protection Agency (EPA) Greenhouse Gas Inventory, EPA Greenhouse Gas Reporting Program, and Emissions Database for Global Atmospheric Research by factors of 1.5, 2.7, and 4.3, respectively. Gathering compressor stations, which accounted for 40% of O&G emissions in our inventory, had the largest difference from emission estimates based on EPA data sources. Our inventory's higher O&G emission estimate was due primarily to its more comprehensive activity factors and inclusion of emissions from fat-tail sites. PMID:26148553

  12. SDSS IV MaNGA - spatially resolved diagnostic diagrams: a proof that many galaxies are LIERs

    NASA Astrophysics Data System (ADS)

    Belfiore, Francesco; Maiolino, Roberto; Maraston, Claudia; Emsellem, Eric; Bershady, Matthew A.; Masters, Karen L.; Yan, Renbin; Bizyaev, Dmitry; Boquien, Médéric; Brownstein, Joel R.; Bundy, Kevin; Drory, Niv; Heckman, Timothy M.; Law, David R.; Roman-Lopes, Alexandre; Pan, Kaike; Stanghellini, Letizia; Thomas, Daniel; Weijmans, Anne-Marie; Westfall, Kyle B.

    2016-09-01

    We study the spatially resolved excitation properties of the ionized gas in a sample of 646 galaxies using integral field spectroscopy data from the Sloan Digital Sky Survey IV Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) programme. Making use of Baldwin-Philips-Terlevich diagnostic diagrams we demonstrate the ubiquitous presence of extended (kpc scale) low-ionization emission-line regions (LIERs) in both star-forming and quiescent galaxies. In star-forming galaxies LIER emission can be associated with diffuse ionized gas, most evident as extraplanar emission in edge-on systems. In addition, we identify two main classes of galaxies displaying LIER emission: `central LIER' (cLIER) galaxies, where central LIER emission is spatially extended, but accompanied by star formation at larger galactocentric distances, and `extended LIER' (eLIER) galaxies, where LIER emission is extended throughout the whole galaxy. In eLIER and cLIER galaxies, LIER emission is associated with radially flat, low H α equivalent width of line emission (<3 Å) and stellar population indices demonstrating the lack of young stellar populations, implying that line emission follows tightly the continuum due to the underlying old stellar population. The H α surface brightness radial profiles are always shallower than 1/r2 and the line ratio [O III] λ5007/[O II] λλ3727,29 (a tracer of the ionization parameter of the gas) shows a flat gradient. This combined evidence strongly supports the scenario in which LIER emission is not due to a central point source but to diffuse stellar sources, the most likely candidates being hot, evolved (post-asymptotic giant branch) stars. Shocks are observed to play a significant role in the ionization of the gas only in rare merging and interacting systems.

  13. Two-layer Model for Measuring the Optical Properties of Turbid Materials Based on Spatially Resolved Hyperspectral Diffuse Reflectance Images

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral imaging-based spatially resolved technique is useful for determining the optical properties of fruits and food products that are homogenous. To better characterize fruit properties and quality attributes, it is desirable that fruit be considered as two homogeneous layers, i.e., skin an...

  14. Optimization of the Hyperspectral Imaging-based Spatially-resolved System for Measuring the Optical Properties of Biological Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper reports on the optimization and assessment of a hyperspectral imaging-based spatially-resolved system for determination of the optical properties of biological materials over the wavelengths of 500-1,000 nm. Twelve model samples covering a wide range of absorption and reduced scattering c...

  15. Spatially-resolved, three-dimensional spray characterization of impinging jets by digital in-line holography

    NASA Astrophysics Data System (ADS)

    Gao, Jian; Rodrigues, Neil; Sojka, Paul; Chen, Jun

    2014-11-01

    The impinging jet injector is a preferred method for the atomization of liquid rocket propellants. The majority of experimental studies in literature are not spatially-resolved due to the limitations of widely available point-wise and two-dimensional (2D) diagnostic techniques such as phase Doppler anemometry (PDA), which requires significant experimental repetitions to give spatially-resolved measurements. In the present study, digital in-line holography (DIH) is used to provide spatially-resolved, three-dimensional (3D) characteristics of impinging jet sprays. A double-exposure DIH setup is configured to measure droplet 3D, three-component velocity as well as the size distribution. The particle information is extracted by the hybrid method, which is recently proposed as a particle detection method. To enlarge the detection volume, two parallel, collimated laser beams are used to simultaneously probe the spray at two locations, and two identical cameras are used to record the corresponding holograms. Such a setup has a detection volume of approximately 20 cm by 3.6 cm by 4.8 cm. Sprays of both Newtonian and non-Newtonian liquids corresponding to regimes at relatively lower jet Reynolds and Weber numbers are investigated. Measurements from DIH are further verified by comparison with experimental data obtained from shadowgraph and PDA. It is revealed that DIH is particularly suitable to provide spatially-resolved, 3D measurements of impinging jet sprays that are not particularly dense.

  16. Temporally and spatially resolved measurements of multi-megagauss magnetic fields in high intensity laser-produced plasmas

    SciTech Connect

    Gopal, A.; Tatarakis, M.; Beg, F. N.; Wei, M. S.; Clark, E. L.; Dangor, A. E.; Evans, R. G.; Norreys, P. A.; Zepf, M.; Krushelnick, K.

    2008-12-15

    We report spatially and temporally resolved measurements of self-generated multi-megagauss magnetic fields produced during ultrahigh intensity laser plasma interactions. Spatially resolved measurements of the magnetic fields show an asymmetry in the distribution of field with respect to the angle of laser incidence. Temporally resolved measurements of the self-generated third harmonic suggest that the strength of the magnetic field is proportional to the square root of laser intensity (i.e., the laser B-field) during the rise of the laser pulse. The experimental results are compared with numerical simulations using a particle-in-cell code which also shows clear asymmetry of the field profile and similar magnetic field growth rates and scalings.

  17. Spatially resolved electroluminescence of InGaN-MQW-LEDs[Multiple Quantum Wells-Light Emitting Diodes

    SciTech Connect

    Schwegler, V.; Seyboth, M.; Kirchner, C.; Scherer, M.; Kamp, M.; Fischer, P.; Christen, J.; Zacharias, M.

    2000-07-01

    Electroluminescence (EL) is the most significant measure for light-emitting diodes since it probes the most relevant properties of the fully processed device during operation. In addition to the information gained by conventional spectrally resolved EL, scanning micro-EL provides spatially resolved information. The devices under investigation are InGaN/GaN-LEDs with single peak band-band emission at about 400 nm grown by MOVPE on sapphire substrates. The {mu}-EL-characterization is performed as a function of injection current densities and the emission is investigated from the epitaxial layer as well as from substrate side. Spatially resolved wavelength images reveal emission peaks between 406 nm and 417 nm, corresponding either to In fluctuations of 1--1.5% or local fluctuations of piezo electric fields. Beside the information on the emission wavelength fluctuations {mu}-EL is used to determine the temperature distribution in the LEDs and to investigate transparent contacts.

  18. QuShape: Rapid, accurate, and best-practices quantification of nucleic acid probing information, resolved by capillary electrophoresis

    PubMed Central

    Karabiber, Fethullah; McGinnis, Jennifer L.; Favorov, Oleg V.; Weeks, Kevin M.

    2013-01-01

    Chemical probing of RNA and DNA structure is a widely used and highly informative approach for examining nucleic acid structure and for evaluating interactions with protein and small-molecule ligands. Use of capillary electrophoresis to analyze chemical probing experiments yields hundreds of nucleotides of information per experiment and can be performed on automated instruments. Extraction of the information from capillary electrophoresis electropherograms is a computationally intensive multistep analytical process, and no current software provides rapid, automated, and accurate data analysis. To overcome this bottleneck, we developed a platform-independent, user-friendly software package, QuShape, that yields quantitatively accurate nucleotide reactivity information with minimal user supervision. QuShape incorporates newly developed algorithms for signal decay correction, alignment of time-varying signals within and across capillaries and relative to the RNA nucleotide sequence, and signal scaling across channels or experiments. An analysis-by-reference option enables multiple, related experiments to be fully analyzed in minutes. We illustrate the usefulness and robustness of QuShape by analysis of RNA SHAPE (selective 2′-hydroxyl acylation analyzed by primer extension) experiments. PMID:23188808

  19. Spatially resolved spectroscopy of WR ring nebulae. I - NGC 2359 and RCW 78

    NASA Astrophysics Data System (ADS)

    Esteban, C.; Vilchez, J. M.; Manchado, A.; Edmunds, M. G.

    1990-01-01

    We report detailed spatially resolved spectroscopy of the WR nebulae NGC 2359 and RCW 78 surrounding the WN 5 HD 56925 and WN 8 HD 117688 stars. The aim of this work has been to study possible abundance inhomogeneities and the ionization structure of the nebulae, as well as to derive reliable values for the degree of self-enrichment. In NGC 2359 the derived ratio O2+/O+ shows localized variations resulting from the compression of the gas in the filaments with respect to the shell gas. Effective temperatures for the central stars of both nebulae have been estimated on the basis of the ionization structure; the values found appear appropriate for their spectral types. Abundances of O/H, NIH, Ne/H, and He/H have been determined in twelve different positions in NGC 2359, covering its different morphological zones. No significant differences in the N/H and O/H abundances across the nebula have been found, although He/H shows marginal evidence for localized enhancements. In the case of RCW 78 the derived value of O/H is roughly solar, but He/H and NIH may be slightly overabundant. The results suggest that the amount of chemical self-enrichment of these WR nebulae is, at most, small.

  20. Using broadband spatially resolved NIRS to assess muscle oxygenation during altered running protocols

    NASA Astrophysics Data System (ADS)

    Koukourakis, Georg; Vafiadou, Maria; Steimers, André; Geraskin, Dmitri; Neary, Patrick; Kohl-Bareis, Matthias

    2009-07-01

    We used spatially resolved near-infrared spectroscopy (SRS-NIRS) to assess calf and thigh muscle oxygenation during running on a motor-driven treadmill. Two protocols were used: An incremental speed protocol (velocity = 6 - 12 km/h, ▵v = 2 km/h) was performed in 3 minute stages, while a pacing paradigm modulated step frequency alternatively (2.3 Hz [SLow]; 3.3 Hz [SHigh]) during a constant velocity for 2 minutes each. A SRS-NIRS broadband system (600 - 1000 nm) was used to measure total haemoglobin concentration and oxygen saturation (SO2). An accelerometer was placed on the hip joints to measure limb acceleration through the experiment. The data showed that the calf (SO2 58 to 42%) desaturated to a significantly lower level than the thigh (61 to 54%). During the pacing protocol, SO2 was significantly different between the SLow vs. SHigh trials. Additionally, physiological data as measured by spirometry were different between the SLow vs. SHigh pacing trials (VO2 (2563+/- 586 vs. 2503 +/- 605 mL/min). Significant differences in VO2 at the same workload (speed) indicate alterations in mechanical efficiency. These data suggest that SRS broadband NIRS can be used to discern small changes in muscle oxygenation, making this device useful for metabolic exercise studies in addition to spirometry and movement monitoring by accelerometers.

  1. Spatially resolved measurements of electron cyclotron resonance ion source beam profile characteristics

    SciTech Connect

    Panitzsch, Lauri; Stalder, Michael; Wimmer-Schweingruber, Robert F.

    2011-03-15

    Simulations predict that the concentric rings and the triangular structures in the profiles of strongly focused ion beams that are found in different experiments should be dominated by ion species with the same or at least similar m/q-ratio. To verify these theoretical predictions we have tuned our ECR ion source to deliver a beam consisting of multiple ion species whose particular m/q-depending focusing ranges from weakly focused to overfocused. We then recorded spatially resolved charge-state distributions of the beam profile at characteristic positions in the plane perpendicular to the beam line. The results validate theoretical predictions and are summarized in this paper. To achieve the required beam profile characteristics we moved the extraction along the beam line to achieve stronger focusing than by only changing the extraction voltage. To fit the regions of interest of the beam profile into the transmission area of the sector magnet, we steered the beam by moving the extraction in the plane perpendicular to the beam axis. The results of both investigations, beam focusing and beam steering by using a 3D-movable extraction, are also reported in this paper. A brief overview of the new beam monitor extensively used during these measurements, the Faraday cup array, is also given.

  2. Multiple spatially resolved reflection spectroscopy for in vivo determination of carotenoids in human skin and blood

    NASA Astrophysics Data System (ADS)

    Darvin, Maxim E.; Magnussen, Björn; Lademann, Juergen; Köcher, Wolfgang

    2016-09-01

    Non-invasive measurement of carotenoid antioxidants in human skin is one of the important tasks to investigate the skin physiology in vivo. Resonance Raman spectroscopy and reflection spectroscopy are the most frequently used non-invasive techniques in dermatology and skin physiology. In the present study, an improved method based on multiple spatially resolved reflection spectroscopy (MSRRS) was introduced. The results obtained were compared with those obtained using the ‘gold standard’ resonance Raman spectroscopy method and showed strong correlations for the total carotenoid concentration (R  =  0.83) as well as for lycopene (R  =  0.80). The measurement stability was confirmed to be better than 10% within the total temperature range from 5 °C to  +  30 °C and pressure contact between the skin and the MSRRS sensor from 800 Pa to 18 000 Pa. In addition, blood samples taken from the subjects were analyzed for carotenoid concentrations. The MSRRS sensor was calibrated on the blood carotenoid concentrations resulting in being able to predict with a correlation of R  =  0.79. On the basis of blood carotenoids it could be demonstrated that the MSRRS cutaneous measurements are not influenced by Fitzpatrick skin types I–VI. The MSRRS sensor is commercially available under the brand name biozoom.

  3. Distribution of Nanoflares as Spatially Resolved Current Sheets in the Solar Corona

    NASA Astrophysics Data System (ADS)

    Ng, C. S.; Lin, L.

    2014-05-01

    In a recent numerical study [Ng et al., Astrophys. J. 747, 109, 2012], based on a three-dimensional model of coronal heating using reduced magnetohydrodynamics, we have obtained scaling results of heating rate versus Lundquist number S based on a series of runs in which random photospheric motions are imposed for hundreds to thousands of Alfvén time in order to obtain converged statistical values. The heating rate found in these simulations saturates to a level that is independent of S in the high S limit and is consistent with the required level for coronal heating. In a previous study based on the total heating rate time series [Ng and Lin, AIP Conf. Proc. 1500, 38, 2012] in these simulations, we have also calculated heating events distributions, which are consistent with observations but do not support the nanoflares scenario [Parker, Astrophys. J. 330, 474, 1988]. This method has a limitation of not distinguishing individual heating events. We now extend this analysis to investigate the distribution of energy release events defined as spatially resolved current sheets [Lin et el., ASP Conf. Ser. 474, 159, 2013]. We report preliminary results and compare to results obtained using only time-series analysis.

  4. A spatially resolved fuel-based inventory of Utah and Colorado oil and natural gas emissions

    NASA Astrophysics Data System (ADS)

    Gorchov Negron, A.; McDonald, B. C.; De Gouw, J. A.; Frost, G. J.

    2015-12-01

    A fuel-based approach is presented for estimating emissions from US oil and natural gas production that utilizes state-level fuel surveys of oil and gas engine activity, well-level production data, and emission factors for oil and gas equipment. Emissions of carbon dioxide (CO2) and nitrogen oxides (NOx) are mapped on a 4 km x 4 km horizontal grid for 2013-14 in Utah and Colorado. Emission sources include combustion from exploration (e.g., drilling), production (e.g., heaters, dehydrators, and compressor engines), and natural gas processing plants, which comprise a large fraction of the local combustion activity in oil and gas basins. Fuel-based emission factors of NOx are from the U.S. Environmental Protection Agency, and applied to spatially-resolved maps of CO2 emissions. Preliminary NOx emissions from this study are estimated for the Uintah Basin, Utah, to be ~5300 metric tons of NO2-equivalent in 2013. Our result compares well with an observations-based top-down emissions estimate of NOx derived from a previous study, ~4200 metric tons of NO2-equivalent. By contrast, the 2011 National Emissions Inventory estimates oil and gas emissions of NOx to be ~3 times higher than our study in the Uintah Basin. We intend to expand our fuel-based approach to map combustion-related emissions in other U.S. oil and natural gas basins and compare with additional observational datasets.

  5. Spatially resolved measurements of charge carrier lifetimes in CdTe solar cells

    NASA Astrophysics Data System (ADS)

    Kraft, C.; Hempel, H.; Buschmann, V.; Siebert, T.; Heisler, C.; Wesch, W.; Ronning, C.

    2013-03-01

    The lifetime of the minority charge carriers in polycrystalline Cadmium Telluride (pc-CdTe) for solar cell applications is a crucial material parameter and has been determined by analysis of the decay curves of the luminescence signal. Both the lateral and the transversal distributions of the carrier lifetime on the surface and in the bulk of pc-CdTe material as well as the respective solar cell characteristics were measured as a function of the deposition technique, the activation treatment, and the incorporation of additional group-V elements. The results are compared to prior studies. It was found that an activation process passivates grain boundaries and increases the carrier lifetime, which is then higher at the pn-junction than at the surface. Furthermore, nitrogen and phosphorus doping of the CdTe absorber material influences the charge carrier lifetime. The results show that the spatial resolved measurement of the carrier lifetime in pc-CdTe gives an important insight to the charge carrier dynamics of the material.

  6. Spatially resolved magnetic field structure in the disk of a T Tauri star.

    PubMed

    Stephens, Ian W; Looney, Leslie W; Kwon, Woojin; Fernández-López, Manuel; Hughes, A Meredith; Mundy, Lee G; Crutcher, Richard M; Li, Zhi-Yun; Rao, Ramprasad

    2014-10-30

    Magnetic fields in accretion disks play a dominant part during the star formation process but have hitherto been observationally poorly constrained. Field strengths have been inferred on T Tauri stars and possibly in the innermost part of their accretion disks, but the strength and morphology of the field in the bulk of a disk have not been observed. Spatially unresolved measurements of polarized emission (arising from elongated dust grains aligned perpendicularly to the field) imply average fields aligned with the disks. Theoretically, the fields are expected to be largely toroidal, poloidal or a mixture of the two, which imply different mechanisms for transporting angular momentum in the disks of actively accreting young stars such as HL Tau (ref. 11). Here we report resolved measurements of the polarized 1.25-millimetre continuum emission from the disk of HL Tau. The magnetic field on a scale of 80 astronomical units is coincident with the major axis (about 210 astronomical units long) of the disk. From this we conclude that the magnetic field inside the disk at this scale cannot be dominated by a vertical component, though a purely toroidal field also does not fit the data well. The unexpected morphology suggests that the role of the magnetic field in the accretion of a T Tauri star is more complex than our current theoretical understanding. PMID:25337883

  7. Spatially resolved star-formation in nearby analogues of Lyman break galaxies

    NASA Astrophysics Data System (ADS)

    Appel, Sabrina; Baker, Andrew J.; Hall, Kirsten

    2016-01-01

    At redshifts of z > 1.5, UV-selected galaxy populations (such as z ~ 3 Lyman break galaxies = LBGs) have the largest number of spectroscopic redshifts. As a result, LBGs have an important role in our understanding of the history of galaxy formation. However, LBGs are rather poorly understood at longer wavelengths, and thus our understanding of the total star formation rates and (especially) gas masses in such galaxies is incomplete. A common strategy is to assume that the Kennicutt-Schmidt relation between star formation rate (SFR) surface density and gas mass surface density holds, even in these high redshift galaxies where testing the relation directly is not feasible. To help assess the validity of this assumption, we examine the Kennicutt-Schmidt relation in selected nearby (z ~ 0.2) starburst galaxies in the hope of better understanding key questions regarding star formation processes in UV-selected galaxies. Several nearby galaxies with high UV luminosities and surface brightnesses, reminiscent of those found in LBGs, were identified and used for this project. We have obtained new, spatially resolved observations of these nearby analogues in Paschen alpha emission and carbon monoxide emission, from the ESO Very Large Telescope and the IRAM Plateau de Bure Interferometer, respectively. We examine whether the galaxies follow the expected Kennicutt-Schmidt relation, and investigate any implied variation in gas depletion times between and within galaxies. This research has been supported by National Science Foundation grant AST-0955810.

  8. Microstructure Imaging Using Frequency Spectrum Spatially Resolved Acoustic Spectroscopy F-Sras

    NASA Astrophysics Data System (ADS)

    Sharples, S. D.; Li, W.; Clark, M.; Somekh, M. G.

    2010-02-01

    Material microstructure can have a profound effect on the mechanical properties of a component, such as strength and resistance to creep and fatigue. SRAS—spatially resolved acoustic spectroscopy—is a laser ultrasonic technique which can image microstructure using highly localized surface acoustic wave (SAW) velocity as a contrast mechanism, as this is sensitive to crystallographic orientation. The technique is noncontact, nondestructive, rapid, can be used on large components, and is highly tolerant of acoustic aberrations. Previously, the SRAS technique has been demonstrated using a fixed frequency excitation laser and a variable grating period (к-vector) to determine the most efficiently generated SAWs, and hence the velocity. Here, we demonstrate an implementation which uses a fixed grating period with a broadband laser excitation source. The velocity is determined by analyzing the measured frequency spectrum. Experimental results using this "frequency spectrum SRAS" (f-SRAS) method are presented. Images of microstructure on an industrially relevant material are compared to those obtained using the previous SRAS method ("k-SRAS"), excellent agreement is observed. Moreover, f-SRAS is much simpler and potentially much more rapid than k-SRAS as the velocity can be determined at each sample point in one single laser shot, rather than scanning the grating period.

  9. The ACS Nearby Galaxies Survey Treasury: Recovering Spatially Resolved Recent Star Formation Histories

    NASA Astrophysics Data System (ADS)

    Skillman, Evan D.; ANGST Team

    2006-12-01

    Because the supergiant phase of stellar evolution is short relative to the main sequence phase, it is possible to use them as chronometers to reconstruct the spatially resolved recent star formation histories of galaxies (cf., Dohm-Palmer et al. 1997, AJ, 114, 2514). Under the aegis of a cycle 14 HST program to observe a sample of M81 group dwarf galaxies (GO-HST-10605), we have used the star formation history codes of Dolphin (2002, MNRAS, 332, 91) to re-engineer the programs used in Dohm-Palmer et al. and produced automated codes with a wide range of applicability. The ANGST database will allow us our first opportunity to make the transition from analyzing prototypes to analyzing a statistically meaningful sample of galaxies. This promises real progress in quantifying the role of feedback in the evolution of galaxies. This work is supported by NASA grants HST-GO-10605.01-A and HST-GO-10915.06-A

  10. Spatially resolved two-color diffusion measurements in human skin applied to transdermal liposome penetration.

    PubMed

    Brewer, Jonathan; Bloksgaard, Maria; Kubiak, Jakub; Sørensen, Jens Ahm; Bagatolli, Luis A

    2013-05-01

    A multiphoton excitation-based fluorescence fluctuation spectroscopy method, Raster image correlation spectroscopy (RICS), was used to measure the local diffusion coefficients of distinct model fluorescent substances in excised human skin. In combination with structural information obtained by multiphoton excitation fluorescence microscopy imaging, the acquired diffusion information was processed to construct spatially resolved diffusion maps at different depths of the stratum corneum (SC). Experiments using amphiphilic and hydrophilic fluorescently labeled molecules show that their diffusion in SC is very heterogeneous on a microscopic scale. This diffusion-based strategy was further exploited to investigate the integrity of liposomes during transdermal penetration. Specifically, the diffusion of dual-color fluorescently labeled liposomes--containing an amphiphilic fluorophore in the lipid bilayer and a hydrophilic fluorophore encapsulated in the liposome lumen--was measured using cross-correlation RICS. This type of experiment allows discrimination between separate (uncorrelated) and joint (correlated) diffusion of the two different fluorescent probes, giving information about liposome integrity. Independent of the liposome composition (phospholipids or transfersomes), our results show a clear lack of cross-correlation below the skin surface, indicating that the penetration of intact liposomes is highly compromised by the skin barrier. PMID:23223136

  11. Spatially Resolved Spectroscopy of Europa: The Distinct Spectrum of Large-scale Chaos

    NASA Astrophysics Data System (ADS)

    Fischer, P. D.; Brown, M. E.; Hand, K. P.

    2015-11-01

    We present a comprehensive analysis of spatially resolved moderate spectral resolution near-infrared spectra obtained with the adaptive optics system at the Keck Observatory. We identify three compositionally distinct end member regions: the trailing hemisphere bullseye, the leading hemisphere upper latitudes, and a third component associated with leading hemisphere chaos units. We interpret the composition of the three end member regions to be dominated by irradiation products, water ice, and evaporite deposits or salt brines, respectively. The third component is associated with geological features and distinct from the geography of irradiation, suggesting an endogenous identity. Identifying the endogenous composition is of particular interest for revealing the subsurface composition. However, its spectrum is not consistent with linear mixtures of the salt minerals previously considered relevant to Europa. The spectrum of this component is distinguished by distorted hydration features rather than distinct spectral features, indicating hydrated minerals but making unique identification difficult. In particular, it lacks features common to hydrated sulfate minerals, challenging the traditional view of an endogenous salty component dominated by Mg-sulfates. Chloride evaporite deposits are one possible alternative.

  12. Spatially resolved spectroscopy for nondestructive quality measurements of Braeburn apples cultivated in sub-fertilization condition

    NASA Astrophysics Data System (ADS)

    Nguyen Do Trong, Nghia; Erkinbaev, Chyngyz; Nicolaï, Bart; Saeys, Wouter; Tsuta, Mizuki; De Baerdemaeker, Josse

    2013-05-01

    A contact spatially resolved spectroscopy (SRS) setup based on a fiber-optics probe in the Vis/NIR range (400-1000 nm) was developed, calibrated, and validated for its measurements and optical properties estimation by means of a metamodeling method on a set of liquid optical phantoms. Thirty Braeburn apples cultivated in sub-fertilization condition were harvested and measured before and after shelf-life storage (2 weeks at 18 °C) by the setup and were analyzed for quality attributes (firmness and soluble solids contents (SSC)) by destructive reference methods. Estimated optical properties (absorption and reduced scattering coefficients) acquired from SRS measurements at the beginning and the end of the shelf-life indicated changes in chemical composition of the apples. Partial Least Squares Regression (PLSR) was employed to construct calibration models relating the estimated optical properties to the reference quality attributes. The constructed PLS models based on the absorption coefficient spectra gave good prediction performance for the quality attributes of the apples in the validation set with correlation coefficients r of 0.901 and r of 0.844, respectively for SSC and firmness. The obtained results clearly show the potential of the SRS measurements for nondestructive quality evaluation of apples.

  13. DARK MATTER SUBSTRUCTURE DETECTION USING SPATIALLY RESOLVED SPECTROSCOPY OF LENSED DUSTY GALAXIES

    SciTech Connect

    Hezaveh, Yashar; Holder, Gilbert; Dalal, Neal; Kuhlen, Michael; Marrone, Daniel; Murray, Norman; Vieira, Joaquin

    2013-04-10

    We investigate how strong lensing of dusty, star-forming galaxies (DSFGs) by foreground galaxies can be used as a probe of dark matter halo substructure. We find that spatially resolved spectroscopy of lensed sources allows dramatic improvements to measurements of lens parameters. In particular, we find that modeling of the full, three-dimensional (angular position and radial velocity) data can significantly facilitate substructure detection, increasing the sensitivity of observables to lower mass subhalos. We carry out simulations of lensed dusty sources observed by early ALMA (Cycle 1) and use a Fisher matrix analysis to study the parameter degeneracies and mass detection limits of this method. We find that even with conservative assumptions, it is possible to detect galactic dark matter subhalos of {approx}10{sup 8} M{sub Sun} with high significance in most lensed DSFGs. Specifically, we find that in typical DSFG lenses, there is a {approx}55% probability of detecting a substructure with M > 10{sup 8} M{sub Sun} with more than 5{sigma} detection significance in each lens, if the abundance of substructure is consistent with previous lensing results. The full ALMA array, with its significantly enhanced sensitivity and resolution, should improve these estimates considerably. Given the sample of {approx}100 lenses provided by surveys such as the South Pole Telescope, our understanding of dark matter substructure in typical galaxy halos is poised to improve dramatically over the next few years.

  14. Spatially resolved electrical characterisation of graphene layers by an evanescent field microwave microscope

    NASA Astrophysics Data System (ADS)

    Gregory, Andrew; Hao, Ling; Klein, Norbert; Gallop, John; Mattevi, Cecilia; Shaforost, Olena; Lees, Kevin; Clarke, Bob

    2014-02-01

    An evanescent field microwave microscope has been developed at the National Physical Laboratory. This instrument has multiple applications and has been developed to allow traceable measurements of local complex permittivity, unlike most other microwave scanning microscopes. In this paper we describe basic operation of the microscope and show measurements on graphene samples produced at Imperial College. The microscope obtains images by raster scanning of a wire probe in ‘contact mode’. Of particular interest to the graphene community is the possibility of being able to scan over large areas (up to 4×4 mm2), and to be able to measure actual values of surface resistance without a requirement for metal contacts. As an ultrathin semimetal, a graphene layer being placed in the evanescent field of the probe is expected to behave like a lossy dielectric material, its microwave loss tangent is proportional to its conductivity. Employing a high Q dual mode re-entrant cavity as host resonator and a spherical metal probe of 180 μm diameter, we found that spatial variations of the conductivity of graphene can be clearly resolved.

  15. Spatially resolved spectroscopy of an impulse plasma for thin film deposition

    NASA Astrophysics Data System (ADS)

    Kułakowska-Pawlak, Barbara

    2009-08-01

    Radially resolved emission measurements have been employed for a better understanding of plasma generated in a pulsed coaxial accelerator operating in a mixture of propane and butane under conditions which enable diamond-like layer deposition. The measurements were taken at two positions along the axis of symmetry of the discharge. Assuming the Boltzmann and Saha equilibrium, the emission from the plasma has been quantified. Abel-transformed radial profiles of the spectral lines of C I, C II and C III have been used to study radial changes in the concentration of excited neutral, singly and doubly ionized carbon, in the excitation temperature, in the ionization temperature and in the electron number density. Values of excitation and ionization temperatures and their radial profiles for a given axial position did not differ significantly. On the axis of symmetry of the discharge, the excitation temperature of C II and the electron density were found to reach values of about 29 000 K and 5 × 1017 cm-3, respectively. In addition, the relative densities of the C, C+ and C2+ species were evaluated, and hence the spatial inhomogeneous plasma structure with respect to the distribution of neutral and ionized fractions of carbon has been revealed and discussed in terms of deposition conditions.

  16. Identification of optical transitions in cubic and hexagonal GaN by spatially resolved cathodoluminescence

    NASA Astrophysics Data System (ADS)

    Menniger, J.; Jahn, U.; Brandt, O.; Yang, H.; Ploog, K.

    1996-01-01

    The hexagonal and cubic phases of GaN are characterized by spatially resolved cathodoluminescence (CL) spectra from micrometer-size single crystals with either hexagonal or cubic habits grown by plasma-assisted molecular-beam epitaxy. At 5 K, distinct narrow excitonic lines are found at 3.472 and 3.272 eV for the hexagonal and cubic phase, yielding energy gaps of 3.500 and 3.300 eV, respectively. Detailed temperature- and intensity-dependent CL measurements on cubic GaN crystals enable us to clearly identify the exciton (free: 3.272 eV, bound: 3.263 eV) and the donor-acceptor pair (3.150 eV) transition. Moreover, we determine the donor-band and acceptor-band transition energy for this phase. In addition, phonon replicas of the exciton line and of the donor-acceptor pair transition are observed at 3.185 and 3.064 eV, respectively.

  17. Spatially resolved vertical vorticity in solar supergranulation using helioseismology and local correlation tracking

    NASA Astrophysics Data System (ADS)

    Langfellner, J.; Gizon, L.; Birch, A. C.

    2015-09-01

    Flow vorticity is a fundamental property of turbulent convection in rotating systems. Solar supergranules exhibit a preferred sense of rotation, which depends on the hemisphere. This is due to the Coriolis force acting on the diverging horizontal flows. We aim to spatially resolve the vertical flow vorticity of the average supergranule at different latitudes, both for outflow and inflow regions. To measure the vertical vorticity, we use two independent techniques: time-distance helioseismology (TD) and local correlation tracking of granules in intensity images (LCT) using data from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Both maps are corrected for center-to-limb systematic errors. We find that 8 h TD and LCT maps of vertical vorticity are highly correlated at large spatial scales. Associated with the average supergranule outflow, we find tangential (vortical) flows that reach about 10 m s-1 in the clockwise direction at 40° latitude. In average inflow regions, the tangential flow reaches the same magnitude, but in the anticlockwise direction. These tangential velocities are much smaller than the radial (diverging) flow component (300 m s-1 for the average outflow and 200 m s-1 for the average inflow). The results for TD and LCT as measured from HMI are in excellent agreement for latitudes between -60° and 60°. From HMI LCT, we measure the vorticity peak of the average supergranule to have a full width at half maximum of about 13 Mm for outflows and 8 Mm for inflows. This is larger than the spatial resolution of the LCT measurements (about 3 Mm). On the other hand, the vorticity peak in outflows is about half the value measured at inflows (e.g., 4 × 10-6 s-1 clockwise compared to 8 × 10-6 s-1 anticlockwise at 40° latitude). Results from the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO) obtained in 2010 are biased compared to the HMI/SDO results for the same period

  18. State-Resolved Quantum Dynamics of Photodetachment of HCO2(-)/DCO2(-) on an Accurate Global Potential Energy Surface.

    PubMed

    Zou, Lindong; Li, Jun; Wang, Hui; Ma, Jianyi; Guo, Hua

    2015-07-16

    Full-dimensional quantum dynamics studies of the photodetachment of HCO2(-) and DCO2(-) are reported using a wave-packet method on an accurate global potential energy surface of the neutral HOCO/HCO2 system. The calculated photoelectron spectra reproduced both the positions and widths of the main HCO2 and DCO2 peaks observed in experiment. Specifically, both the (2)A1 and (2)B2 resonance peaks of the neutral radicals were identified in our simulations thanks to the adiabatic PES that captures both the (2)A1 and (2)B2 minima. The narrow widths and isotope effect of the lowest resonances are indicative of tunneling-facilitated predissociation. Furthermore, the dissociation product CO2 was found to be excited in both its symmetric stretching and bending modes, which are coupled via a strong Fermi resonance, but rotationally cold, in good agreement with the recent photoelectron-photodetachment coincidence experiments. PMID:25607218

  19. Dose calculation for permanent prostate implants incorporating spatially anisotropic linearly time-resolving edema

    SciTech Connect

    Monajemi, T. T.; Clements, Charles M.; Sloboda, Ron S.

    2011-04-15

    Purpose: The objectives of this study were (i) to develop a dose calculation method for permanent prostate implants that incorporates a clinically motivated model for edema and (ii) to illustrate the use of the method by calculating the preimplant dosimetry error for a reference configuration of {sup 125}I, {sup 103}Pd, and {sup 137}Cs seeds subject to edema-induced motions corresponding to a variety of model parameters. Methods: A model for spatially anisotropic edema that resolves linearly with time was developed based on serial magnetic resonance imaging measurements made previously at our center to characterize the edema for a group of n=40 prostate implant patients [R. S. Sloboda et al., ''Time course of prostatic edema post permanent seed implant determined by magnetic resonance imaging,'' Brachytherapy 9, 354-361 (2010)]. Model parameters consisted of edema magnitude, {Delta}, and period, T. The TG-43 dose calculation formalism for a point source was extended to incorporate the edema model, thus enabling calculation via numerical integration of the cumulative dose around an individual seed in the presence of edema. Using an even power piecewise-continuous polynomial representation for the radial dose function, the cumulative dose was also expressed in closed analytical form. Application of the method was illustrated by calculating the preimplant dosimetry error, RE{sub preplan}, in a 5x5x5 cm{sup 3} volume for {sup 125}I (Oncura 6711), {sup 103}Pd (Theragenics 200), and {sup 131}Cs (IsoRay CS-1) seeds arranged in the Radiological Physics Center test case 2 configuration for a range of edema relative magnitudes ({Delta}=[0.1,0.2,0.4,0.6,1.0]) and periods (T=[28,56,84] d). Results were compared to preimplant dosimetry errors calculated using a variation of the isotropic edema model developed by Chen et al. [''Dosimetric effects of edema in permanent prostate seed implants: A rigorous solution,'' Int. J. Radiat. Oncol., Biol., Phys. 47, 1405-1419 (2000

  20. A Simple Iterative Model Accurately Captures Complex Trapline Formation by Bumblebees Across Spatial Scales and Flower Arrangements

    PubMed Central

    Reynolds, Andrew M.; Lihoreau, Mathieu; Chittka, Lars

    2013-01-01

    Pollinating bees develop foraging circuits (traplines) to visit multiple flowers in a manner that minimizes overall travel distance, a task analogous to the travelling salesman problem. We report on an in-depth exploration of an iterative improvement heuristic model of bumblebee traplining previously found to accurately replicate the establishment of stable routes by bees between flowers distributed over several hectares. The critical test for a model is its predictive power for empirical data for which the model has not been specifically developed, and here the model is shown to be consistent with observations from different research groups made at several spatial scales and using multiple configurations of flowers. We refine the model to account for the spatial search strategy of bees exploring their environment, and test several previously unexplored predictions. We find that the model predicts accurately 1) the increasing propensity of bees to optimize their foraging routes with increasing spatial scale; 2) that bees cannot establish stable optimal traplines for all spatial configurations of rewarding flowers; 3) the observed trade-off between travel distance and prioritization of high-reward sites (with a slight modification of the model); 4) the temporal pattern with which bees acquire approximate solutions to travelling salesman-like problems over several dozen foraging bouts; 5) the instability of visitation schedules in some spatial configurations of flowers; 6) the observation that in some flower arrays, bees' visitation schedules are highly individually different; 7) the searching behaviour that leads to efficient location of flowers and routes between them. Our model constitutes a robust theoretical platform to generate novel hypotheses and refine our understanding about how small-brained insects develop a representation of space and use it to navigate in complex and dynamic environments. PMID:23505353

  1. Spatially resolved assessment of hepatic function using 99mTc-IDA SPECT

    SciTech Connect

    Wang, Hesheng; Cao, Yue

    2013-09-15

    Purpose: 99mTc-iminodiacetic acid (IDA) hepatobiliary imaging is usually quantified for hepatic function on the entire liver or regions of interest (ROIs) in the liver. The authors presented a method to estimate the hepatic extraction fraction (HEF) voxel-by-voxel from single-photon emission computed tomography (SPECT)/CT with a 99mTc-labeled IDA agent of mebrofenin and evaluated the spatially resolved HEF measurements with an independent physiological measurement.Methods: Fourteen patients with intrahepatic cancers were treated with radiation therapy (RT) and imaged by 99mTc-mebrofenin SPECT before and 1 month after RT. The dynamic SPECT volumes were with a resolution of 3.9 × 3.9 × 2.5 mm{sup 3}. Throughout the whole liver with approximate 50 000 voxels, voxelwise HEF quantifications were estimated and compared between using arterial input function (AIF) from the heart and using vascular input function (VIF) from the spleen. The correlation between mean of the HEFs over the nontumor liver tissue and the overall liver function measured by Indocyanine green clearance half-time (T1/2) was assessed. Variation of the voxelwise estimation was evaluated in ROIs drawn in relatively homogeneous regions of the livers. The authors also examined effects of the time range parameter on the voxelwise HEF quantification.Results: Mean of the HEFs over the liver estimated using AIF significantly correlated with the physiological measurement T1/2 (r= 0.52, p= 0.0004), and the correlation was greatly improved by using VIF (r= 0.79, p < 0.0001). The parameter of time range for the retention phase did not lead to a significant difference in the means of the HEFs in the ROIs. Using VIF and a retention phase time range of 7–30 min, the relative variation of the voxelwise HEF in the ROIs was 10%± 6% of respective mean HEF.Conclusions: The voxelwise HEF derived from 99mTc-IDA SPECT by the deconvolution analysis is feasible to assess the spatial distribution of hepatic function in the

  2. Temporally and spatially resolved characterization of microwave induced argon plasmas: Experiment and modeling

    NASA Astrophysics Data System (ADS)

    Baeva, M.; Andrasch, M.; Ehlbeck, J.; Loffhagen, D.; Weltmann, K.-D.

    2014-04-01

    Experiments and modeling of the plasma-microwave interaction have been performed in a coaxial microwave plasma source at a field frequency of 2.45 GHz generating argon plasmas at pressures of 20 and 40 millibars and a ratio of flow rate to pressure of 0.125 sccm/Pa. The incident microwave power between 100 W and 300 W is supplied in a regime of a pulse-width modulation with cycle duration of 110 ms and a power-on time of 23 ms. The experiments are based on heterodyne reflectometry and microwave interferometry at 45.75 GHz. They provide the temporal behaviour of the complex reflection coefficient, the microwave power in the plasma, as well as the electron density in the afterglow zone of the discharge. The self-consistent spatially two-dimensional and time-dependent modeling complements the analysis of the plasma-microwave interaction delivering the plasma and electromagnetic field parameters. The consolidating experimental observations and model predictions allow further characterizing the plasma source. The generated plasma has a core occupying the region close to the end of the inner electrode, where maximum electron densities above 1020 m-3 and electron temperatures of about 1 eV are observed. Due to a longer outer electrode of the coaxial structure, the plasma region is extended and fills the volume comprised by the outer electrode. The electron density reaches values of the order of 1019 m-3. The heating of the gas occurs in its great part due to elastic collisions with the plasma electrons. However, the contribution of the convective heating is important especially in the extended plasma region, where the gas temperature reaches its maximum values up to approximately 1400 K. The temporally and spatially resolved modeling enables a thorough investigation of the plasma-microwave interaction which clearly shows that the power in-coupling occurs in the region of the highest electron density during the early stage of the discharge. In the steady state phase

  3. SPATIALLY RESOLVED POLYCYCLIC AROMATIC HYDROCARBON EMISSION FEATURES IN NEARBY, LOW METALLICITY, STAR-FORMING GALAXIES

    SciTech Connect

    Haynes, Korey; Cannon, John M.; Skillman, Evan D.; Gehrz, Robert; Jackson, Dale C. E-mail: khaynes5@gmu.ed E-mail: gehrz@astro.umn.ed

    2010-11-20

    Low-resolution, mid-infrared Spitzer/IRS spectral maps are presented for three nearby, low-metallicity dwarf galaxies (NGC 55, NGC 3109, and IC 5152) for the purpose of examining the spatial distribution and variation of polycyclic aromatic hydrocarbon (PAH) emission. The sample straddles a metallicity of 12 + log(O/H) {approx} 8, a transition point below which PAH intensity empirically drops and the character of the interstellar medium changes. We derive quantitative radiances of PAH features and atomic lines on both global and spatially resolved scales. The Spitzer spectra, combined with extensive ancillary data from the UV through the mid-infrared, allow us to examine changes in the physical environments and in PAH feature radiances down to a physical scale of {approx}50 pc. We discuss correlations between various PAH emission feature and atomic line radiances. The (6.2 {mu}m)/(11.3 {mu}m), (7.7 {mu}m)/(11.3 {mu}m), (8.6 {mu}m)/(11.3 {mu}m), (7.7 {mu}m)/(6.2 {mu}m), and (8.6 {mu}m)/(6.2 {mu}m) PAH radiance ratios are found to be independent of position across all three galaxies, although the ratios do vary from galaxy to galaxy. As seen in other galaxies, we find no variation in the grain size distribution as a function of local radiation field strength. Absolute PAH feature intensities as measured by a ratio of PAH/(24 {mu}m) radiances are seen to vary both positionally within a given galaxy and from one galaxy to another when integrated over the full observed extent of each system. We examine direct comparisons of CC mode PAH ratios (7.7 {mu}m)/(6.2 {mu}m) and (8.6 {mu}m)/(6.2 {mu}m) to the mixed (CC/CH) mode PAH ratio (7.7 {mu}m)/(11.3 {mu}m). We find little variation in either mode and no difference in trends between modes. While the local conditions change markedly over the observed regions of these galaxies, the properties of PAH emission show a remarkable degree of uniformity.

  4. Temporally and spatially resolved characterization of microwave induced argon plasmas: Experiment and modeling

    SciTech Connect

    Baeva, M. Andrasch, M.; Ehlbeck, J.; Loffhagen, D.; Weltmann, K.-D.

    2014-04-14

    Experiments and modeling of the plasma-microwave interaction have been performed in a coaxial microwave plasma source at a field frequency of 2.45 GHz generating argon plasmas at pressures of 20 and 40 millibars and a ratio of flow rate to pressure of 0.125 sccm/Pa. The incident microwave power between 100 W and 300 W is supplied in a regime of a pulse-width modulation with cycle duration of 110 ms and a power-on time of 23 ms. The experiments are based on heterodyne reflectometry and microwave interferometry at 45.75 GHz. They provide the temporal behaviour of the complex reflection coefficient, the microwave power in the plasma, as well as the electron density in the afterglow zone of the discharge. The self-consistent spatially two-dimensional and time-dependent modeling complements the analysis of the plasma-microwave interaction delivering the plasma and electromagnetic field parameters. The consolidating experimental observations and model predictions allow further characterizing the plasma source. The generated plasma has a core occupying the region close to the end of the inner electrode, where maximum electron densities above 10{sup 20} m{sup −3} and electron temperatures of about 1 eV are observed. Due to a longer outer electrode of the coaxial structure, the plasma region is extended and fills the volume comprised by the outer electrode. The electron density reaches values of the order of 10{sup 19} m{sup −3}. The heating of the gas occurs in its great part due to elastic collisions with the plasma electrons. However, the contribution of the convective heating is important especially in the extended plasma region, where the gas temperature reaches its maximum values up to approximately 1400 K. The temporally and spatially resolved modeling enables a thorough investigation of the plasma-microwave interaction which clearly shows that the power in-coupling occurs in the region of the highest electron density during the early stage of

  5. Temporal and spatial resolved optical emission behaviors of a cold atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Xiong, Q.; Lu, X.; Liu, J.; Xian, Y.; Xiong, Z.; Zou, F.; Zou, C.; Gong, W.; Hu, J.; Chen, K.; Pei, X.; Jiang, Z.; Pan, Y.

    2009-10-01

    The propagation behavior of cold atmospheric pressure plasma jets has recently attracted lots of attention. In this paper, a cold He plasma jet generated by a single plasma electrode jet device is studied. The spatial-temporal resolved optical emission spectroscopy measurements are presented. It is found that the emission intensity of the He 706.5 nm line of the plasma behaves similarly both inside the syringe and in the surrounding air (plasma plume). It decreases monotonously, which is different from the emission lines, such as N2 337.1 nm line, N2+ 391.4 nm line, and O 777.3 nm line. For the discharge inside the syringe, the emission intensity of the He 706.5 nm line decays more rapidly than that of the other three spectral lines mentioned above. The N2 337.1 nm line behaves a similar time evolution with the discharge current. For the N2+ 391.4 nm line and the atomic O 777.3 nm line, both of them decay slower than that of the He 706.5 nm and the N2 337.1 nm. When the plasma plume propagates further away from the nozzle, the temporal behaviors of the emission intensities of the four lines tend to be similar gradually. Besides, it is found that, when the size of the plasma bullet appears biggest, the propagation velocity of the bullet achieves its highest value while the emission intensity of the N2+ 391.4 nm line reaches its maximum. Detailed analysis shows that the Penning effect between the metastable state Hem and the air molecules may play a significant role in the propagation of the plasma bullet in the open air.

  6. Scene from above: retinal ganglion cell topography and spatial resolving power in the giraffe (Giraffa camelopardalis).

    PubMed

    Coimbra, João Paulo; Hart, Nathan S; Collin, Shaun P; Manger, Paul R

    2013-06-15

    The giraffe (Giraffa camelopardalis) is a browser that uses its extensible tongue to selectively collect leaves during foraging. As the tallest extant terrestrial mammal, its elevated head height provides panoramic surveillance of the environment. These aspects of the giraffe's ecology and phenotype suggest that vision is of prime importance. Using Nissl-stained retinal wholemounts and stereological methods, we quantitatively assessed the retinal specializations in the ganglion cell layer of the giraffe. The mean total number of retinal ganglion cells was 1,393,779 and their topographic distribution revealed the presence of a horizontal visual streak and a temporal area. With a mean peak of 14,271 cells/mm(2), upper limits of spatial resolving power in the temporal area ranged from 25 to 27 cycles/degree. We also observed a dorsotemporal extension (anakatabatic area) that tapers toward the nasal retina giving rise to a complete dorsal arch. Using neurofilament-200 immunohistochemistry, we also detected a dorsal arch formed by alpha ganglion cells with density peaks in the temporal (14-15 cells/mm(2)) and dorsonasal (10 cells/mm(2)) regions. As with other artiodactyls, the giraffe shares the presence of a horizontal streak and a temporal area which, respectively, improve resolution along the horizon and in the frontal visual field. The dorsal arch is related to the giraffe's head height and affords enhanced resolution in the inferior visual field. The alpha ganglion cell distribution pattern is unique to the giraffe and enhances acquisition of motion information for the control of tongue movement during foraging and the detection of predators. PMID:23595815

  7. Spatially resolved Raman studies of diamond films grown by chemical vapor deposition

    SciTech Connect

    Ager, J.W. III; Veirs, D.K.; Rosenblatt, G.M. )

    1991-03-15

    The frequency and line shape of the diamond Raman line are examined in detail for a series of microwave-plasma-assisted chemical-vapor-deposition films grown on Si. The Raman lines in the films appear at higher frequency (shifts of up to 3 cm{sup {minus}1}) than that of natural diamond and the observed lines are symmetric with broader linewidths than that of natural diamond, ranging from 5.7 to 17.1 cm{sup {minus}1}. In addition, the line frequencies and linewidths are correlated; the films with the highest vibrational frequencies have the largest linewidths. The data include single-point measurements on eight films grown under different conditions as well as 500 data points from different positions on a single film that were obtained in a spatially resolved Raman experiment. Several mechanisms for the frequency shift and the correlation of the linewidth with frequency are considered including phonon confinement, residual stress, and defect scattering. Contrary to the observations, Raman line shapes computed from the phonon-confinement model (which has been used successfully to model Raman scattering in microcrystalline Si and GaAs), using phonon-dispersion curves for diamond from the literature, are highly asymmetric at the linewidths observed. It is concluded that the observed shifts in the diamond Raman line do not arise from phonon confinement alone and arise primarily from compressive stress. The line broadening also is not produced by phonon confinement alone and may arise from decreasing phonon lifetime associated with scattering from defects or from an inhomogeneous stress distribution in the films. The observed correlation between Raman line frequency and width suggests that the degree of compressive stress may be associated with the density of microcrystalline defects.

  8. Constraining sub-grid physics with high-redshift spatially-resolved metallicity distributions

    NASA Astrophysics Data System (ADS)

    Gibson, B. K.; Pilkington, K.; Brook, C. B.; Stinson, G. S.; Bailin, J.

    2013-06-01

    Aims: We examine the role of energy feedback in shaping the distribution of metals within cosmological hydrodynamical simulations of L∗ disc galaxies. While negative abundance gradients today provide a boundary condition for galaxy evolution models, in support of inside-out disc growth, empirical evidence as to whether abundance gradients steepen or flatten with time remains highly contradictory. Methods: We made use of a suite of L∗ discs, realised with and without "enhanced" feedback. All the simulations were produced using the smoothed particle hydrodynamics code Gasoline, and their in situ gas-phase metallicity gradients traced from redshift z ~ 2 to the present-day. Present-day age-metallicity relations and metallicity distribution functions were derived for each system. Results: The "enhanced" feedback models, which have been shown to be in agreement with a broad range of empirical scaling relations, distribute energy and re-cycled ISM material over large scales and predict the existence of relatively "flat" and temporally invariant abundance gradients. Enhanced feedback schemes reduce significantly the scatter in the local stellar age-metallicity relation and, especially, the [O/Fe]-[Fe/H] relation. The local [O/Fe] distribution functions for our L∗ discs show clear bimodality, with peaks at [O/Fe] = -0.05 and + 0.05 (for stars with [Fe/H] > -1), consistent with our earlier work on dwarf discs. Conclusions: Our results with "enhanced" feedback are inconsistent with our earlier generation of simulations realised with "conservative" feedback. We conclude that spatially-resolved metallicity distributions, particularly at high-redshift, offer a unique and under-utilised constraint on the uncertain nature of stellar feedback processes.

  9. Fueling active galactic nuclei. II. Spatially resolved molecular inflows and outflows

    SciTech Connect

    Davies, R. I.; Erwin, P.; Burtscher, L.; Lin, M.; Orban de Xivry, G.; Rosario, D. J.; Schnorr-Müller, A.; Maciejewski, W.; Hicks, E. K. S.; Emsellem, E.; Dumas, G.; Malkan, M. A.; Müller-Sánchez, F.; Tran, A.

    2014-09-10

    We analyze the two-dimensional distribution and kinematics of the stars as well as molecular and ionized gas in the central few hundred parsecs of five active and five matched inactive galaxies. The equivalent widths of the Brγ line indicate that there is no ongoing star formation in their nuclei, although recent (terminated) starbursts are possible in the active galaxies. The stellar velocity fields show no signs of non-circular motions, while the 1-0 S(1) H{sub 2} kinematics exhibit significant deviations from simple circular rotation. In the active galaxies the H{sub 2} kinematics reveal inflow and outflow superimposed on disk rotation. Steady-state circumnuclear inflow is seen in three active galactic nuclei (AGNs), and hydrodynamical models indicate it can be driven by a large-scale bar. In three of the five AGNs, molecular outflows are spatially resolved. The outflows are oriented such that they intersect, or have an edge close to, the disk, which may be the source of molecular gas in the outflow. The relatively low speeds imply the gas will fall back onto the disk, and with moderate outflow rates, they will have only a local impact on the host galaxy. H{sub 2} was detected in two inactive galaxies. These exhibit chaotic circumnuclear dust morphologies and have molecular structures that are counter-rotating with respect to the main gas component, which could lead to gas inflow in the near future. In our sample, all four galaxies with chaotic dust morphology in the circumnuclear region exist in moderately dense groups with 10-15 members where accretion of stripped gas can easily occur.

  10. Diffusion and spatially resolved NMR in Berea and Venezuelan oil reservoir rocks.

    PubMed

    Murgich, J; Corti, M; Pavesi, L; Voltini, F

    1992-01-01

    Conventional and spatially resolved proton NMR and relaxation measurements are used in order to study the molecular motions and the equilibrium and nonequilibrium diffusion of oils in Berea sandstone and Venezuelan reservoir rocks. In the water-saturated Berea a single line with T*2 congruent to 150 microseconds is observed, while the relaxation recovery is multiexponential. In an oil reservoir rock (Ful 13) a single narrow line is present while a distribution of relaxation rates is evidenced from the recovery plots. On the contrary, in the Ful 7 sample (extracted at a deeper depth in a different zone) two NMR components are present, with 3.5 and 30 KHz linewidths, and the recovery plot exhibits biexponential law. No echo signal could be reconstructed in the oil reservoir rocks. These findings can be related to the effects in the micropores, where motions at very low frequency can occur in a thin layer. From a comparison of the diffusion constant in water-saturated Berea, D congruent to 5*10(-6) cm2/sec, with the ones in model systems, the average size of the pores is estimated around 40 A. The density profiles at the equilibrium show uniform distribution of oils or of water, and the relaxation rates appear independent from the selected slice. The nonequilibrium diffusion was studied as a function of time in a Berea cylinder with z axis along H0, starting from a thin layer of oil at the base, and detecting the spin density profiles d(z,t) with slice-selection techniques. Simultaneously, the values of T1's were measured locally, and the distribution of the relaxation rates was observed to be present in any slice.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1461080

  11. Cerebral oxygenation monitoring during cardiac bypass surgery in infants with broad band spatially resolved spectroscopy

    NASA Astrophysics Data System (ADS)

    Soschinski, Jan; Ben Mine, Lofti; Geraskin, Dmitri; Bennink, Gerardus; Kohl-Bareis, Matthias

    2007-07-01

    Neurological impairments following cardio-pulmonary bypass (CPB) during open heart surgery can result from microembolism and ischaemia. Here we present results from monitoring cerebral haemodynamics during CPB with near infrared spatially resolved broadband spectroscopy. In particular, the study has the objective (a) to monitor oxy- and deoxy-hemoglobin concentrations (oxy-Hb, deoxy-Hb) and their changes as well as oxygen saturation during CPB surgery and (b) to develop and test algorithms for the calculation of these parameters from broad band spectroscopy. For this purpose a detection system was developed based on an especially designed lens imaging spectrograph with optimised sensitivity of recorded reflectance spectra for wavelengths between 600 and 1000 nm. The high f/#-number of 1:1.2 of the system results in about a factor of 10 higher light throughput combined with a lower astigmatism and crosstalk between channels when compared with a commercial mirror spectrometers (f/# = 1:4). For both hemispheres two independent channels each with three source-detector distances (ρ = 25 . 35 mm) were used resulting in six spectra. The broad band approach allows to investigate the influence of the wavelength range on the calculated haemoglobin concentrations and their changes and oxygen saturation when the attenuation A(λ) and its slope ΔA(λ)/Δρ are evaluated. Furthermore, the different depth sensitivities of these measurement parameters are estimated from Monte Carlo simulations and exploited for an optimization of the cerebral signals. It is demonstrated that the system does record cerebral oxygenation parameters during CPB in infants. In particular, the correlation of haemoglobin concentrations with blood supply (flow, pressure) by the heart-lung machine and the significant decreases in oxygen saturation during cardiac arrest is discussed.

  12. Spatially-Resolved Hydraulic Conductivity Estimation Via Poroelastic Magnetic Resonance Elastography

    PubMed Central

    McGarry, Matthew; Weaver, John B.; Paulsen, Keith D.

    2015-01-01

    Poroelastic magnetic resonance elastography is an imaging technique that could recover mechanical and hydrodynamical material properties of in vivo tissue. To date, mechanical properties have been estimated while hydrodynamical parameters have been assumed homogeneous with literature-based values. Estimating spatially-varying hydraulic conductivity would likely improve model accuracy and provide new image information related to a tissue’s interstitial fluid compartment. A poroelastic model was reformulated to recover hydraulic conductivity with more appropriate fluid-flow boundary conditions. Simulated and physical experiments were conducted to evaluate the accuracy and stability of the inversion algorithm. Simulations were accurate (property errors were < 2%) even in the presence of Gaussian measurement noise up to 3%. The reformulated model significantly decreased variation in the shear modulus estimate (p≪0.001) and eliminated the homogeneity assumption and the need to assign hydraulic conductivity values from literature. Material property contrast was recovered experimentally in three different tofu phantoms and the accuracy was improved through soft-prior regularization. A frequency-dependence in hydraulic conductivity contrast was observed suggesting that fluid-solid interactions may be more prominent at low frequency. In vivo recovery of both structural and hydrodynamical characteristics of tissue could improve detection and diagnosis of neurological disorders such as hydrocephalus and brain tumors. PMID:24771571

  13. Efficient and accurate laser shaping with liquid crystal spatial light modulators

    SciTech Connect

    Maxson, Jared M.; Bartnik, Adam C.; Bazarov, Ivan V.

    2014-10-27

    A phase-only spatial light modulator (SLM) is capable of precise transverse laser shaping by either functioning as a variable phase grating or by serving as a variable mask via polarization rotation. As a phase grating, the highest accuracy algorithms, based on computer generated holograms (CGHs), have been shown to yield extended laser shapes with <10% rms error, but conversely little is known about the experimental efficiency of the method in general. In this work, we compare the experimental tradeoff between error and efficiency for both the best known CGH method and polarization rotation-based intensity masking when generating hard-edged flat top beams. We find that the masking method performs comparably with CGHs, both having rms error < 10% with efficiency > 15%. Informed by best practices for high efficiency from a SLM phase grating, we introduce an adaptive refractive algorithm which has high efficiency (92%) but also higher error (16%), for nearly cylindrically symmetric cases.

  14. Efficient and accurate laser shaping with liquid crystal spatial light modulators

    NASA Astrophysics Data System (ADS)

    Maxson, Jared M.; Bartnik, Adam C.; Bazarov, Ivan V.

    2014-10-01

    A phase-only spatial light modulator (SLM) is capable of precise transverse laser shaping by either functioning as a variable phase grating or by serving as a variable mask via polarization rotation. As a phase grating, the highest accuracy algorithms, based on computer generated holograms (CGHs), have been shown to yield extended laser shapes with <10% rms error, but conversely little is known about the experimental efficiency of the method in general. In this work, we compare the experimental tradeoff between error and efficiency for both the best known CGH method and polarization rotation-based intensity masking when generating hard-edged flat top beams. We find that the masking method performs comparably with CGHs, both having rms error < 10% with efficiency > 15%. Informed by best practices for high efficiency from a SLM phase grating, we introduce an adaptive refractive algorithm which has high efficiency (92%) but also higher error (16%), for nearly cylindrically symmetric cases.

  15. Evaluating Mesoscale Numerical Weather Predictions and Spatially Distributed Meteorologic Forcing Data for Developing Accurate SWE Forecasts over Large Mountain Basins

    NASA Astrophysics Data System (ADS)

    Hedrick, A. R.; Marks, D. G.; Winstral, A. H.; Marshall, H. P.

    2014-12-01

    The ability to forecast snow water equivalent, or SWE, in mountain catchments would benefit many different communities ranging from avalanche hazard mitigation to water resource management. Historical model runs of Isnobal, the physically based energy balance snow model, have been produced over the 2150 km2 Boise River Basin for water years 2012 - 2014 at 100-meter resolution. Spatially distributed forcing parameters such as precipitation, wind, and relative humidity are generated from automated weather stations located throughout the watershed, and are supplied to Isnobal at hourly timesteps. Similarly, the Weather Research & Forecasting (WRF) Model provides hourly predictions of the same forcing parameters from an atmospheric physics perspective. This work aims to quantitatively compare WRF model output to the spatial meteorologic fields developed to force Isnobal, with the hopes of eventually using WRF predictions to create accurate hourly forecasts of SWE over a large mountainous basin.

  16. The CALIFA survey across the Hubble sequence. Spatially resolved stellar population properties in galaxies

    NASA Astrophysics Data System (ADS)

    González Delgado, R. M.; García-Benito, R.; Pérez, E.; Cid Fernandes, R.; de Amorim, A. L.; Cortijo-Ferrero, C.; Lacerda, E. A. D.; López Fernández, R.; Vale-Asari, N.; Sánchez, S. F.; Mollá, M.; Ruiz-Lara, T.; Sánchez-Blázquez, P.; Walcher, C. J.; Alves, J.; Aguerri, J. A. L.; Bekeraité, S.; Bland-Hawthorn, J.; Galbany, L.; Gallazzi, A.; Husemann, B.; Iglesias-Páramo, J.; Kalinova, V.; López-Sánchez, A. R.; Marino, R. A.; Márquez, I.; Masegosa, J.; Mast, D.; Méndez-Abreu, J.; Mendoza, A.; del Olmo, A.; Pérez, I.; Quirrenbach, A.; Zibetti, S.

    2015-09-01

    Various different physical processes contribute to the star formation and stellar mass assembly histories of galaxies. One important approach to understanding the significance of these different processes on galaxy evolution is the study of the stellar population content of today's galaxies in a spatially resolved manner. The aim of this paper is to characterize in detail the radial structure of stellar population properties of galaxies in the nearby universe, based on a uniquely large galaxy sample, considering the quality and coverage of the data. The sample under study was drawn from the CALIFA survey and contains 300 galaxies observed with integral field spectroscopy. These cover a wide range of Hubble types, from spheroids to spiral galaxies, while stellar masses range from M⋆ ~ 109 to 7 × 1011 M⊙. We apply the fossil record method based on spectral synthesis techniques to recover the following physical properties for each spatial resolution element in our target galaxies: the stellar mass surface density (μ⋆), stellar extinction (AV), light-weighted and mass-weighted ages (⟨log age⟩L, ⟨log age⟩M), and mass-weighted metallicity (⟨log Z⋆⟩M). To study mean trends with overall galaxy properties, the individual radial profiles are stacked in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd). We confirm that more massive galaxies are more compact, older, moremetal rich, and less reddened by dust. Additionally, we find that these trends are preserved spatially with the radial distance to the nucleus. Deviations from these relations appear correlated with Hubble type: earlier types are more compact, older, and more metal rich for a given M⋆, which is evidence that quenching is related to morphology, but not driven by mass. Negative gradients of ⟨log age⟩L are consistent with an inside-out growth of galaxies, with the largest ⟨log age⟩L gradients in Sb-Sbc galaxies. Further, the mean stellar ages of disks and bulges are

  17. Accurate Object Recognition Using Orientation Sensor with Refinement on the Lie Group of Spatial Rigid Motions

    NASA Astrophysics Data System (ADS)

    Merckel, Loic; Nishida, Toyoaki

    In this paper, we introduce a method for recognizing a subject complex object in real world environment. We use a three dimensional model described by line segments of the object and the data provided by a three-axis orientation sensor attached to the video camera. We assume that existing methods for finding line features in the image allow at least one model line segment to be detected as a single continuous segment. The method consists of two main steps: generation of pose hypotheses and then evaluation of each pose in order to select the most appropriate one. The first stage is three-fold: model visibility, line matching and pose estimation; the second stage aims to rank the poses by evaluating the similarity between the projected model lines and the image lines. Furthermore, we propose an additional step that consists of refining the best candidate pose by using the Lie group formalism of spatial rigid motions. Such a formalism provides an efficient local parameterization of the set of rigid rotation via the exponential map. A set of experiments demonstrating the robustness of this approach is presented.

  18. Enabling accurate photodiode detection of multiple optical traps by spatial filtering

    NASA Astrophysics Data System (ADS)

    Ott, Dino; Reihani, S. Nader S.; Oddershede, Lene B.

    2014-09-01

    Dual and multiple beam optical tweezers allow for advanced trapping geometries beyond single traps, however, these increased manipulation capabilities, usually complicate the detection of position and force. The accuracy of position and force measurements is often compromised by crosstalk between the detected signals, this crosstalk leading to a systematic error on the measured forces and distances. In dual-beam optical trapping setups, the two traps are typically orthogonal polarized and crosstalk can be minimized by inserting polarization optics in front of the detector, however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required high numerical aperture optics. Moreover, the restriction to two orthogonal polarisation states limits the number of detectable traps to two. Here, we present an easy-to-implement simple method to efficiently eliminate cross-talk in dual beam setups.1 The technique is based on spatial filtering and is highly compatible with standard back-focal-plane photodiode based detection. The reported method significantly improves the accuracy of force-distance measurements, e.g., of single molecules, hence providing much more scientific value for the experimental efforts. Furthermore, it opens the possibility for fast and simultaneous photodiode based detection of multiple holographically generated optical traps.

  19. Measurement of Temporally and Spatially Resolved Electron Density in the Filament of a Pulsed Spark Discharge in Water

    NASA Astrophysics Data System (ADS)

    Niu, Zhiwen; Wen, Xiaoqiong; Ren, Chunsheng; Qiu, Yuliang

    2016-08-01

    The temporally and spatially resolved optical emission spectrum of Hα of a pulsed spark discharge in water was experimentally measured. The temporally and spatially resolved electron densities, along the radial direction of the spark filament, for a pulsed spark discharge in water with a conductivity of 100 μS/cm were investigated. The electron density in the spark filament was found to be in the 1018/cm3 order of magnitude. The highest electron density was measured at the primary stage of the spark filament, and it decreased with time. The radial distribution of electron density increased from the center to the edge of the spark filament. supported in part by National Natural Science Foundation of China (Nos. 11275040 and 51437002)

  20. Experimental measurement of spatially resolved electron density in a filament of a pulsed positive streamer discharge in water

    SciTech Connect

    Wen, Xiao Qiong; Niu, Zhi Wen; Ren, Chun-Sheng; Hou, Bo

    2015-06-29

    By combining a high-speed frame camera with a monochromator, the spatially resolved optical emission spectrum of hydrogen α line in a single filament of a pulsed positive streamer discharge in water has been experimentally measured. The spatially resolved electron densities in a single filament of a pulsed positive streamer discharge in water with a conductivity of 200 μS/cm were investigated. During the experiment, the average energy per pulse of discharge was 90.6 ± 13.6 mJ. The results show that the electron density in the streamer filament is 10{sup 17–18}/cm{sup 3}, and present a decreasing tendency along the axial direction of the streamer filament with increasing distance from the tip of the anode.

  1. Spatially resolved dusty torus toward the red supergiant WOH G64 in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Ohnaka, K.; Driebe, T.; Hofmann, K.-H.; Weigelt, G.; Wittkowski, M.

    2008-06-01

    Aims: We present N-band spectro-interferometric observations of the red supergiant WOH G64 in the Large Magellanic Cloud (LMC) using MIDI at the Very Large Telescope Interferometer (VLTI). While the very high luminosity (˜ 5 × 105 L⊙) previously estimated for WOH G64 suggests that it is a very massive star with an initial mass of ~40 M⊙, its low effective temperature (~3200 K) is in serious disagreement with the current stellar evolution theory. Methods: WOH G64 was observed with VLTI/MIDI using the UT2-UT3 and UT3-UT4 baseline configurations. Results: The dust envelope around WOH G64 has been spatially resolved with a baseline of ~60 m - the first MIDI observations to resolve an individual stellar source in an extragalactic system. The observed N-band visibilities show a slight decrease from 8 to ~10 μm and a gradual increase longward of ~10 μm, reflecting the 10 μm silicate feature in self-absorption. This translates into a steep increase of the uniform-disk diameter from 8 to 10 μm (from 18 to 26 mas) and a roughly constant diameter above 10 μm. The visibilities measured at four position angles differing by ~60° but at approximately the same baseline length (~60 m) do not show a noticeable difference, suggesting that the object appears nearly centrosymmetric. The observed N-band visibilities and spectral energy distribution can be reproduced by an optically and geometrically thick silicate torus model viewed close to pole-on. The luminosity of the central star is derived to be ˜ 2.8 × 105 L⊙, which is by a factor of 2 lower than the previous estimates based on spherical models. We also identify the H2O absorption features at 2.7 and 6 μm in the spectra obtained with the Infrared Space Observatory and the Spitzer Space Telescope. The 2.7 μm feature originates in the photosphere and/or the extended molecular layers, while the 6 μm feature is likely to be of circumstellar origin. Conclusions: The lower luminosity newly derived from our MIDI

  2. Accurate multi-source forest species mapping using the multiple spectral-spatial classification approach

    NASA Astrophysics Data System (ADS)

    Stavrakoudis, Dimitris; Gitas, Ioannis; Karydas, Christos; Kolokoussis, Polychronis; Karathanassi, Vassilia

    2015-10-01

    This paper proposes an efficient methodology for combining multiple remotely sensed imagery, in order to increase the classification accuracy in complex forest species mapping tasks. The proposed scheme follows a decision fusion approach, whereby each image is first classified separately by means of a pixel-wise Fuzzy-Output Support Vector Machine (FO-SVM) classifier. Subsequently, the multiple results are fused according to the so-called multiple spectral- spatial classifier using the minimum spanning forest (MSSC-MSF) approach, which constitutes an effective post-regularization procedure for enhancing the result of a single pixel-based classification. For this purpose, the original MSSC-MSF has been extended in order to handle multiple classifications. In particular, the fuzzy outputs of the pixel-based classifiers are stacked and used to grow the MSF, whereas the markers are also determined considering both classifications. The proposed methodology has been tested on a challenging forest species mapping task in northern Greece, considering a multispectral (GeoEye) and a hyper-spectral (CASI) image. The pixel-wise classifications resulted in overall accuracies (OA) of 68.71% for the GeoEye and 77.95% for the CASI images, respectively. Both of them are characterized by high levels of speckle noise. Applying the proposed multi-source MSSC-MSF fusion, the OA climbs to 90.86%, which is attributed both to the ability of MSSC-MSF to tackle the salt-and-pepper effect, as well as the fact that the fusion approach exploits the relative advantages of both information sources.

  3. Spatially-resolved stable isotope analysis of a hypersaline microbial mat

    NASA Astrophysics Data System (ADS)

    Moran, J.; Cory, A. B.; Lindemann, S. R.; Fredrickson, J. K.

    2012-12-01

    Hot Lake is a hypersaline, meromictic lake located in north-central Washington. High rates of evapotranspiration coupled with its location in an endorrheic basin contribute to the lake's high salinity. The predominant dissolved salt is magnesium sulfate; hypolimnion waters may seasonally exceed 2 M magnesium sulfate concentrations. In addition to extreme salinity, horizons within the lake seasonally exceed 50 °C, in part due to the enhanced light absorption by magnesium sulfate-saturated water. Despite extreme and highly variable seasonal conditions (salinity, temperature, photon flux), dense benthic microbial mats composed of cyanobacteria and bacterial heterotroph populations develop annually at the lake. These mats may exceed 5 mm in thickness and display stratification observable by eye associated with dominant bacterial phototrophic pigments. Typical mat stratification includes an orange surface layer followed by green and purple layers at increasing depth into the mat. Carbonates including aragonite and magnesite are observed within the mat and their formation is likely induced or influenced by microbial activities. While not exclusively limited to the green stratum in the mat, maximum carbonate content is within this layer. We are exploring the role Hot Lake's microbial mats play in carbon cycling within the system. Namely, we seek to understand the rates of carbon accumulation in the mat and associated sediments and the various forms this carbon takes (organic or inorganic species). We are assessing mat development, community composition, and carbon accumulation in pre-cleaned devices installed at the lake as they are colonized by native mat. We are using laser ablation isotope ratio mass spectrometry (LA-IRMS) to provide spatially-resolved stable isotope analysis of mat cross-sections. Currently, this technique permits isotope analysis at the 50 μm scale, and can provide multiple isotope analyses within the thickness of each major layer of the mat. We

  4. Spatially resolved integral field spectroscopy of the ionized gas in IZw18

    NASA Astrophysics Data System (ADS)

    Kehrig, C.; Vílchez, J. M.; Pérez-Montero, E.; Iglesias-Páramo, J.; Hernández-Fernández, J. D.; Duarte Puertas, S.; Brinchmann, J.; Durret, F.; Kunth, D.

    2016-07-01

    We present a detailed 2D study of the ionized ionized interstellar medium (ISM) of IZw18 using new Potsdam Multi-Aperture Spectrophotometer-integral field unit (PMAS-IFU) optical observations. IZw18 is a high-ionization galaxy which is among the most metal-poor starbursts in the local Universe. This makes IZw18 a local benchmark for understanding the properties most closely resembling those prevailing at distant starbursts. Our IFU aperture (˜1.4 × 1.4 kpc2) samples the entire IZw18 main body and an extended region of its ionized gas. Maps of relevant emission lines and emission line ratios show that higher-excitation gas is preferentially located close to the north-west knot and thereabouts. We detect a Wolf-Rayet feature near the north-west knot. We derive spatially resolved and integrated physical-chemical properties for the ionized gas in IZw18. We find no dependence between the metallicity indicator R23 and the ionization parameter (as traced by [O III]/[O II]) across IZw18. Over ˜0.30 kpc2, using the [O III] λ4363 line, we compute Te[O III] values (˜15 000-25 000 K), and oxygen abundances are derived from the direct determinations of Te[O III]. More than 70 per cent of the higher-Te[O III] (≳22 000 K) spaxels are He IIλ4686-emitting spaxels too. From a statistical analysis, we study the presence of variations in the ISM physical-chemical properties. A galaxy-wide homogeneity, across hundreds of parsecs, is seen in O/H. Based on spaxel-by-spaxel measurements, the error-weighted mean of 12 + log(O/H) = 7.11 ± 0.01 is taken as the representative O/H for IZw18. Aperture effects on the derivation of O/H are discussed. Using our IFU data we obtain, for the first time, the IZw18 integrated spectrum.

  5. Spatially Resolved HST/STIS Observations of io's Dayside Equatorial Atmosphere

    NASA Astrophysics Data System (ADS)

    Jessup, Kandis-Lea; Spencer, John

    2013-10-01

    We present a detailed analysis of 2011/2012 HST/STIS near ultraviolet (NUV) observations of Io’s dayside equatorial atmosphere. Our results indicate that i) Io’s atmosphere is not in instantaneous equilibrium with the surface frosts; ii) that the level of SO2 continuum emission on Io’s dayside in regions free of any known persistent volcanic plume source is 50x greater than the volcano free disk average brightness of Io during eclipse; and iii) that Io’s dayside SO2 gas density is longitudinally variant, peaking near 167W. This latter result is also evident in previously obtained NUV and near infrared observations (c.f. Tsang et al. 2013); thus, supporting the idea that Io’s dayside SO2 longitudinal variability is static. At the same time, comparison of spatially resolved spectral observations of Io obtained in 2011 and 2001 indicates that Io’s equatorial gas density was higher by a factor of 2 in 2011. This result is consistent with the gas density variation predicted by vapor pressure equilibrium, based on the frost temperature variation expected as a function of heliocentric distance and the relative difference in the heliocentric distance of Io on those dates. Thus, this result suggests that Io’s atmosphere is sublimation dominated. Trends in Io’s SO2 gas density distribution map closely to the variability of Io’s NUV surface reflectance levels. Because the NUV brightness does not map directly to the total SO2 frost abundance (Doute et al. 2001), the reason for the close correlation between the SO2 gas density and the NUV brightness is not fully understood. The NUV brightness seems to correlate with 200-400 μm SO2 frost grains (McEwen et al. 1988, Calrson et al. 1997), but it may also represent the level of molecular contamination of the SO2frost by other volcanic constituents (Doute et al. 2001). Since each of these properties uniquely impacts the rate of gas production for a sublimation supported atmosphere, these relationships must be

  6. Modeling spatially and spectrally resolved observations to diagnose the formation of elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Snyder, Gregory Frantz

    2013-03-01

    In extragalactic astronomy, a central challenge is that we cannot directly watch what happens to galaxies before and after they are observed. This dissertation focuses on linking predictions of galaxy time-evolution directly with observations, evaluating how interactions, mergers, and other processes affect the appearance of elliptical galaxies. The primary approach is to combine hydrodynamical simulations of galaxy formation, including all major components, with dust radiative transfer to predict their observational signatures The current paradigm implies that a quiescent elliptical emerges following a formative starburst event. These trigger accretion onto the central supermassive black hole (SMBH), which then radiates as an active galactic nucleus (AGN). However, it is not clear the extent to which SMBH growth is fueled by these events nor how important is their energy input at setting the appearance of the remnant. This thesis presents results drawing from three phases in the formation of a typical elliptical: 1) I evaluate how to disentangle AGN from star formation signatures in mid-infrared spectra during a dust-enshrouded starburst, making testable predictions for robustly tracing SMBH growth with the James Webb Space Telescope; 2) I develop a model for the rate of merger-induced post-starburst galaxies selected from optical spectra, resolving tension between their observed rarity and merger rates from other estimates; and 3) I present results from Hubble Space Telescope imaging of elliptical galaxies in galaxy clusters at 1 < z < 2, the precursors of present-day massive clusters with M ~ 1015 solar masses, demonstrating that their stars formed over an extended period and ruling out the simplest model for their formation history. These results lend support to a stochastic formation history for ellipticals driven by mergers or interactions. However, significant uncertainties remain in how to evaluate the implications of galaxy appearance, in particular their

  7. Spatially Resolved Far-Ultraviolet Spectroscopy of the Nuclear Region of NGC 1068

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Wang, Jun-Xian; Kriss, Gerard A.; Sahnow, David; Allen, Mark; Dopita, Michael; Tsvetanov, Zlatan; Bicknell, Geoffrey

    2008-10-01

    We carry out high-resolution FUSE spectroscopy of the nuclear region of NGC 1068. The first set of spectra was obtained with a 30'' square aperture that collected all emission from the narrow-line region. The data reveal a strong broad O VI component of FWHM ~3500 km s-1 and two narrow O VI λλ1031, 1037 components of ~350 km s-1. The C III λ977 and N III λ991 emission lines in this spectrum can be fitted with a narrow component of FWHM ~1000 km s-1 and a broad one of ~2500 km s-1. Another set of seven spatially resolved spectra was made using a long slit of 1.25'' × 20'' at steps of ~1'' along the axis of the emission-line cone. We find the following: (1) Major emission lines in the FUSE wavelength range consist of a broad and a narrow component. (2) There is a gradient in the velocity field for the narrow O VI component of ~200 km s-1 from ~2'' southwest of the nucleus to ~4'' northeast. A similar pattern is also observed with the broad O VI component, with a gradient of ~3000 km s-1. These are consistent with the HST STIS findings and suggest a biconical structure in which the velocity field is mainly radial outflow. (3) A major portion of the C III and N III line flux is produced in the compact core. They are therefore not effective temperature diagnostics for the conical region. (4) The best-fit UV continuum suggests virtually no reddening, and the He II I(λ1640)/I(λ1085) ratio suggests a consistently low extinction factor across the cone. At ~2'' northeast of the nucleus there is a region characterized by (a) a strong Lyα flux but normal C IV flux, (b) a broad O VI line, and (c) a significantly enhanced C III flux. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer (FUSE), which is operated for NASA by The Johns Hopkins University under NASA contract NAS5-32985, and observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of

  8. Spatially-resolved carbon flow through a hypersaline phototrophic microbial mat

    NASA Astrophysics Data System (ADS)

    Moran, J.; Lindemann, S. R.; Cory, A. B.; Courtney, S.; Cole, J. K.; Fredrickson, J.

    2013-12-01

    analysis (via elemental analysis IRMS and gas bench IRMS) we are employing laser ablation IRMS (LA-IRMS) to provide a spatially-resolved accounting of label uptake through the mat cross section. This technique permits isotope analysis at the 50 μm scale, and can provide multiple isotope analyses within each mat strata. By coupling LA-IRMS analysis with laminar sectioning of the mat and amplicon sequencing of the rrnA gene, we seek to establish linkages between phylogeny and function over the course of a diel cycle with highlighted emphasis on evidence of carbon transfer between mat laminae and the phylotypes that inhabit them. We are also using a series of carbon accumulation microcosms to quantify net carbon fixation over the seasonal cycle. These microcosms are deployed at multiple depths to provide an accounting of carbon cycling under the specific geochemical conditions experienced at variable depth. Coupling the data from these individual microcosms to our bathymetric survey of Hot Lake permits us to estimate total mat carbon fixation, and therefore to begin to assess the impact of the mat on the greater lake carbon cycle.

  9. In-Situ Observations of Phase Transformations During Welding of 1045 Steel using Spatially Resolved and Time Resolved X-Ray Diffraction

    SciTech Connect

    Elmer, J; Palmer, T; DebRoy, T

    2005-10-28

    Synchrotron-based methods have been developed at Lawrence Livermore National Laboratory (LLNL) for the direct observation of microstructure evolution during welding. These techniques, known as spatially resolved (SRXRD) and time resolved (TRXRD) x-ray diffraction, allow in-situ experiments to be performed during welding and provide direct observations of high temperature phases that form under the intense thermal cycles that occur. This paper presents observations of microstructural evolution that occur during the welding of a medium carbon AISI 1045 steel, using SRXRD to map the phases that are present during welding, and TRXRD to dynamically observe transformations during rapid heating and cooling. SRXRD was further used to determine the influence of welding heat input on the size of the high temperature austenite region, and the time required to completely homogenize this region during welding. These data can be used to determine the kinetics of phase transformations under the steep thermal gradients of welds, as well as benchmark and verify phase transformation models.

  10. Spatially resolved HST/STIS observations of Io's dayside equatorial atmosphere

    NASA Astrophysics Data System (ADS)

    Jessup, Kandis Lea; Spencer, John R.

    2015-03-01

    We report on an investigation of the spatial distribution of Io's atmosphere, and its diurnal variability, using Hubble's Space Telescope Imaging Spectrograph (HST/STIS). From December 2010 to January 2012, we obtained spatially resolved limb-to-limb 2100-3100 Å spectra at low latitudes (<30°), with the STIS 0.1″ slit. Spectra taken at two central meridian longitudes (CMLs), 200 and 250W, over regions that are both bright and dark at near-UV (3000-4000 Å) wavelengths, allowed investigation of the variation in atmospheric density with terrain type and local time. The combined longitudinal coverage of these observations extends from 120 to 320W longitude, and observations of the 200-250W longitude region are obtained at 2 distinct times of day, differing by 50° of rotation of Io. Using primarily SO2 gas absorptions from 2100 to 2300 Å, we detect SO2 gas densities ranging from 0.3 to 2.2 × 1017 cm-2, and 100-200 K gas temperatures. Because we avoided known persistent plume sites, and see little enhancement of SO2 density near known active volcanic centers, we conclude that SO2 gas densities ∼2 × 1017 cm-2 can be obtained via sublimation alone. We correct column densities at each location to equatorial values by assuming vapor-pressure equilibrium with frost at temperatures that vary as cosine1/4(latitude), as inferred from earlier low latitude HST/STIS observations (Jessup, K.L., Spencer, J.R., Ballester, G.E., Howell, R.R., Roesler, F., Vigil, M., Yelle, R. [2004]. Icarus 169, 197-215). Inferred equatorial SO2 gas densities in the 120-320W longitude range show the following behavior: (i) rapid decrease from longitude 170W to 310W, consistent with previous disk-integrated 19 μm and 2100 Å spectroscopy (Spencer, J.R., Lellouch, E., Richter, M.J., López-Valverde, M.A., Jessup, K.L., Greathouse, T.K., Flaud, J.M. [2005]. Icarus 176, 283-304; Tsang, C.C.C., Spencer, J.R., Jessup, K.L. [2013]. Icarus 226, 604-616) and Ly-α imaging (Feaga, L.M., McGrath, M

  11. A comparison between constant volume induction times and results from spatially resolved simulation of ignition behind reflected shocks: implications for shock tube experiments

    NASA Astrophysics Data System (ADS)

    Melguizo-Gavilanes, J.; Bauwens, L.

    2013-05-01

    The induction time measured in shock tube experiments is typically converted into kinetic data assuming that the reaction takes place in a constant volume process, thus neglecting spatial gradients. The actual process of shock ignition is, however, both time- and space-dependent; ignition takes place at a well-defined location, and subsequently a front travels, which may couple with the pressure wave that it created and forms a detonation wave behind the shock that reflects off the wall. To assess how different the actual processes are compared with the constant volume assumption, a numerical study was performed using a simplified three step chain-branching kinetic scheme. To overcome the difficulties that arise when simulating shock-induced ignition due to the initial absence of a domain filled with shocked reactive mixture, the problem is solved in a transformed frame of reference. Furthermore, initial conditions are derived from short-time asymptotics, which resolves the initial singularity. The induction times obtained using the full unsteady formulation with those of the homogeneous explosion are compared for various values of the heat release. Results for the spatially dependent formulation show that the evolution of the post-shock flow is complex, and that it leads to a gradient in induction times, after the passage of the reflected shock. For all cases simulated, thermal explosion initially occurs very close to the wall, and the corresponding induction time is found to be larger than that predicted under the constant volume assumption. As the measurement is made further away however, the actual time interval between passage of the reflected shock, and the specified pressure increase denoting ignition, decreases to a value close to zero, corresponding to that obtained along a Rayleigh line matching that of a steady ZND process (assuming a long enough tube). In situations where the constant volume assumption is expected to be weak, more accurate kinetic data

  12. High-temperature aerosol formation in wood pellets flames: Spatially resolved measurements

    SciTech Connect

    Wiinikka, Henrik; Gebart, Rikard; Boman, Christoffer; Bostroem, Dan; Nordin, Anders; OEhman, Marcus

    2006-12-15

    The formation and evolution of high-temperature aerosols during fixed bed combustion of wood pellets in a realistic combustion environment were investigated through spatially resolved experiments. The purpose of this work was to investigate the various stages of aerosol formation from the hot flame zone to the flue gas channel. The investigation is important both for elucidation of the formation mechanisms and as a basis for development and validation of particle formation models that can be used for design optimization. Experiments were conducted in an 8-kW-updraft fired-wood-pellets combustor. Particle samples were withdrawn from the centerline of the combustor through 10 sampling ports by a rapid dilution sampling probe. The corresponding temperatures at the sampling positions were in the range 200-1450{sup o}C. The particle sample was size-segregated in a low-pressure impactor, allowing physical and chemical resolution of the fine particles. The chemical composition of the particles was investigated by SEM/EDS and XRD analysis. Furthermore, the experimental results were compared to theoretical models for aerosol formation processes. The experimental data show that the particle size distribution has two peaks, both of which are below an aerodynamic diameter of 2.5 {mu}m (PM{sub 2.5}). The mode diameters of the fine and coarse modes in the PM{sub 2.5} region were {approx}0.1 and {approx}0.8 {mu}m, respectively. The shape of the particle size distribution function continuously changes with position in the reactor due to several mechanisms. Early, in the flame zone, both the fine mode and the coarse mode in the PM{sub 2.5} region were dominated by particles from incomplete combustion, indicated by a significant amount of carbon in the particles. The particle concentrations of both the fine and the coarse mode decrease rapidly in the hot oxygen-rich flame due to oxidation of the carbon-rich particles. After the hot flame, the fine mode concentration and particle

  13. In pursuit of an accurate spatial and temporal model of biomolecules at the atomistic level: a perspective on computer simulation

    PubMed Central

    Gray, Alan; Harlen, Oliver G.; Harris, Sarah A.; Khalid, Syma; Leung, Yuk Ming; Lonsdale, Richard; Mulholland, Adrian J.; Pearson, Arwen R.; Read, Daniel J.; Richardson, Robin A.

    2015-01-01

    Despite huge advances in the computational techniques available for simulating biomolecules at the quantum-mechanical, atomistic and coarse-grained levels, there is still a widespread perception amongst the experimental community that these calculations are highly specialist and are not generally applicable by researchers outside the theoretical community. In this article, the successes and limitations of biomolecular simulation and the further developments that are likely in the near future are discussed. A brief overview is also provided of the experimental biophysical methods that are commonly used to probe biomolecular structure and dynamics, and the accuracy of the information that can be obtained from each is compared with that from modelling. It is concluded that progress towards an accurate spatial and temporal model of biomacromolecules requires a combination of all of these biophysical techniques, both experimental and computational. PMID:25615870

  14. All optical method for investigation of spin and charge transport in semiconductors: Combination of spatially and time-resolved luminescence

    SciTech Connect

    Cadiz, F.; Paget, D.; Grebenkov, D.; Korb, J. P.; Rowe, A. C. H.; Barate, P.; Amand, T.; Arscott, S.; Peytavit, E.

    2014-07-14

    A new approach is demonstrated for investigating charge and spin diffusion as well as surface and bulk recombination in unpassivated doped semiconductors. This approach consists in using two complementary, conceptually related, techniques, which are time-resolved photoluminescence (TRPL) and spatially resolved microluminescence (μPL) and is applied here to p{sup +} GaAs. Analysis of the sole TRPL signal is limited by the finite risetime. On the other hand, it is shown that joint TRPL and μPL can be used to determine the diffusion constant, the bulk recombination time, and the spin relaxation time. As an illustration, the temperature variation of these quantities is investigated for p{sup +} GaAs.

  15. Investigation of the Spatially Resolved Electronic Structure of Single Layer WS2 on Transition Metal Oxide Surfaces

    NASA Astrophysics Data System (ADS)

    Katoch, Jyoti; Ulstrup, Søren; Koch, Roland; Schwarz, Daniel; Singh, Simranjeet; McCreary, Kathy; Keun Yoo, Hyang; Xu, Jinsong; Jonker, Berry; Kawakami, Roland; Bostwick, Aaron; Rotenberg, Eli; Jozwiak, Chris

    The family of semiconducting single layer (SL) transition metal dichalcogenides (TMDs) have lately been intensely studied, owing to the strong coupling between spin and valley degrees of freedom as well as the presence of strongly bound excitons. The choice of supporting substrate is known to strongly influence these properties. We set out to investigate the electronic properties of CVD grown SL WS2 transferred onto the dielectric oxide materials SrTiO3 and TiO2. By using a combination of photoemission electron microscopy (PEEM) and angle-resolved photoemission (ARPES) with micrometer focus we obtain simultaneous spatial, momentum and energy-resolved information about SL WS2 on a polar (SrTiO3) and a nonpolar (TiO2) surface for the first time.

  16. SPATIALLY RESOLVED STAR FORMATION IMAGE AND THE ULTRALUMINOUS X-RAY SOURCE POPULATION IN NGC 2207/IC 2163

    SciTech Connect

    Mineo, S.; Rappaport, S.; Steinhorn, B.; Levine, A.; Gilfanov, M.; Pooley, D. E-mail: sar@mit.edu E-mail: bsteinho@mit.edu E-mail: gilfanov@mpa-garching.mpg.de

    2013-07-10

    The colliding galaxy pair NGC 2207/IC 2163, at a distance of {approx}39 Mpc, was observed with Chandra, and an analysis reveals 28 well resolved X-ray sources, including 21 ultraluminous X-ray sources (ULXs) with L{sub X} {approx}> 10{sup 39} erg s{sup -1}, as well as the nucleus of NGC 2207. The number of ULXs is comparable with the largest numbers of ULXs per unit mass in any galaxy yet reported. In this paper we report on these sources, and quantify how their locations correlate with the local star formation rates seen in spatially resolved star formation rate density images that we have constructed using combinations of GALEX FUV and Spitzer 24 {mu}m images. We show that the numbers of ULXs are strongly correlated with the local star formation rate densities surrounding the sources, but that the luminosities of these sources are not strongly correlated with star formation rate density.

  17. Inverse Algorithm Optimization for Determining Optical Properties of Biological Materials from Spatially-Resolved Diffuse Reflectance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Optical characterization of biological materials is useful in many scientific and industrial applications like biomedical diagnosis and nondestructive quality evaluation of food and agricultural products. However, accurate determination of the optical properties from intact biological materials base...

  18. Modelling the Constraints of Spatial Environment in Fauna Movement Simulations: Comparison of a Boundaries Accurate Function and a Cost Function

    NASA Astrophysics Data System (ADS)

    Jolivet, L.; Cohen, M.; Ruas, A.

    2015-08-01

    Landscape influences fauna movement at different levels, from habitat selection to choices of movements' direction. Our goal is to provide a development frame in order to test simulation functions for animal's movement. We describe our approach for such simulations and we compare two types of functions to calculate trajectories. To do so, we first modelled the role of landscape elements to differentiate between elements that facilitate movements and the ones being hindrances. Different influences are identified depending on landscape elements and on animal species. Knowledge were gathered from ecologists, literature and observation datasets. Second, we analysed the description of animal movement recorded with GPS at fine scale, corresponding to high temporal frequency and good location accuracy. Analysing this type of data provides information on the relation between landscape features and movements. We implemented an agent-based simulation approach to calculate potential trajectories constrained by the spatial environment and individual's behaviour. We tested two functions that consider space differently: one function takes into account the geometry and the types of landscape elements and one cost function sums up the spatial surroundings of an individual. Results highlight the fact that the cost function exaggerates the distances travelled by an individual and simplifies movement patterns. The geometry accurate function represents a good bottom-up approach for discovering interesting areas or obstacles for movements.

  19. SPATIALLY AND SPECTRALLY RESOLVED HYDROGEN GAS WITHIN 0.1 AU OF T TAURI AND HERBIG Ae/Be STARS

    SciTech Connect

    Eisner, J. A.; Monnier, J. D.; Woillez, J.; Ragland, S.; Wizinowich, P.; Akeson, R. L.; Millan-Gabet, R.; Graham, J. R.; Hillenbrand, L. A.; Pott, J.-U.

    2010-08-01

    We present near-infrared observations of T Tauri and Herbig Ae/Be stars with a spatial resolution of a few milliarcseconds and a spectral resolution of {approx}2000. Our observations spatially resolve gas and dust in the inner regions of protoplanetary disks, and spectrally resolve broad-linewidth emission from the Br{gamma} transition of hydrogen gas. We use the technique of spectro-astrometry to determine centroids of different velocity components of this gaseous emission at a precision orders of magnitude better than the angular resolution. In all sources, we find the gaseous emission to be more compact than or distributed on similar spatial scales to the dust emission. We attempt to fit the data with models including both dust and Br{gamma}-emitting gas, and we consider both disk and infall/outflow morphologies for the gaseous matter. In most cases where we can distinguish between these two models, the data show a preference for infall/outflow models. In all cases, our data appear consistent with the presence of some gas at stellocentric radii of {approx}0.01 AU. Our findings support the hypothesis that Br{gamma} emission generally traces magnetospherically driven accretion and/or outflows in young star/disk systems.

  20. Spatially resolving the atmospheric dynamics over the surface of red supergiants with the Very Large Telescope Interferometer

    NASA Astrophysics Data System (ADS)

    Ohnaka, K.

    2013-05-01

    The mass-loss mechanism in red supergiants is a long-stand-ing problem. The milliarcsecond angular resolution achieved by infrared long-baseline interferometry provides us with the only way to spatially resolve the region where the material is accelerated. For this goal, the 2.3 μm CO lines are important, because they form in the upper photosphere and the outer atmosphere (so-called MOLsphere). We present high-spatial and high-spectral resolution observations of the 2.3 μm CO lines in the red supergiants Betelgeuse and Antares using the Very Large Telescope Interferometer (VLTI). This has enabled us to spatially resolve the gas dynamics in the photosphere (and the MOLsphere) for the first time other than the Sun. We have detected vigorous motions of large CO gas clumps with velocities of up to 20-30 km s-1. Comparison of the CO line data taken 1 year apart shows a significant change in the dynamics of the atmosphere. In contrast to the CO line data, the continuum data reveal no or only marginal time variations. The observationally estimated gas density in the outer atmosphere at 1.3-1.4 R⋆ is higher than the values predicted by the current 3-D convection simulations by 6 to 11 orders of magnitude. Therefore, at the moment, convection alone cannot explain the detected vigorous gas motions in the extended outer atmosphere of Betelgeuse and Antares.

  1. Spatially resolved chemical imaging of individual atmospheric particles using nanoscale imaging mass spectrometry: insight into particle origin and chemistry

    DOE PAGESBeta

    Ghosal, Sutapa; Weber, Peter K.; Laskin, Alexander

    2014-01-14

    Knowledge of the spatially resolved composition of atmospheric particles is essential for differentiating between their surface versus bulk chemistry and understanding particle reactivity and the potential environmental impact. Here, we demonstrate the application of nanometer-scale secondary ion mass spectrometry (CAMECA NanoSIMS 50 ion probe) for 3D chemical imaging of individual atmospheric particles without any sample pre-treatment, such as sectioning of particles. Use of NanoSIMS depth profile analysis enables elemental mapping of particles with nanometer spatial resolution over a broad range of particle sizes. We have used this technique to probe the spatially resolved composition of ambient particles collected during amore » field campaign in Mexico City. Particles collected during this campaign have been extensively characterized in the past using other particle analysis techniques and hence offer a unique opportunity for exploring the utility of depth-resolved chemical imaging in ambient particle research. The particles that we examined in our study include those collected during a pollution episode related to urban waste incineration as well as background particles from the same location before the episode. Particles from the pollution episode show substantial intra-particle compositional variability typical of particles resulting from multiple emission sources. In contrast, the background particles have relatively homogeneous compositions with enhanced presence of nitrogen, oxygen, and chlorine at the particle surface. We also observed the surface enhancement of nitrogen and oxygen species is consistent with the presence of surface nitrates resulting from gas–particle heterogeneous interactions and is indicative of atmospheric ageing of the particles. The results presented here illustrate 3D characterization of ambient particles for insight into their chemical history.« less

  2. Spatially resolved chemical imaging of individual atmospheric particles using nanoscale imaging mass spectrometry: Insighs into particle origin and chemistry

    SciTech Connect

    Ghosal, Sutapa; Weber, Peter K.; Laskin, Alexander

    2014-04-21

    Knowledge of the spatially-resolved composition of atmospheric particles is essential for differentiating between their surface versus bulk chemistry, understanding particle reactivity and the potential environmental impact. We demonstrate the application of nanometer-scale secondary ion mass spectrometry (Cameca NanoSIMS 50 ion probe) for 3D chemical imaging of individual atmospheric particles without any sample pre-treatment, such as the sectioning of particles. Use of NanoSIMS depth profile analysis enables elemental mapping of particles with nanometer spatial resolution over a broad of range of particle sizes. We have used this technique to probe spatially resolved composition of ambient particles collected during a field campaign in Mexico City. Particles collected during this campaign have been extensively characterized in the past using other particle analysis techniques and hence offer a unique opportunity for exploring the utility of depth resolved chemical imaging in ambient particle research. 1 Particles examined in this study include those collected during a pollution episode related to urban waste incineration as well as background particles from the same location prior to the episode. Particles from the pollution episode show substantial intra-particle compositional variability typical of particles resulting from multiple emission sources. In contrast, the background particles have relatively homogeneous compositions with enhanced presence of nitrogen, oxygen and chlorine at the particle surface. The observed surface enhancement of nitrogen and oxygen species is consistent with the presence of surface nitrates resulting from gas-particle heterogeneous interactions and is indicative of atmospheric ageing of the particles. The results presented here illustrate 3D characterization of ambient particles for insights into their chemical history.

  3. Spatially resolved chemical imaging of individual atmospheric particles using nanoscale imaging mass spectrometry: Insights into particle origin and chemistry

    NASA Astrophysics Data System (ADS)

    Ghosal, S.; Weber, P. K.; Laskin, A.

    2014-12-01

    Knowledge of the spatially-resolved composition of atmospheric particles is essential for differentiating between their surface versus bulk chemistry, understanding particle reactivity and the potential environmental impact. We demonstrate the application of nanometer-scale secondary ion mass spectrometry (Cameca NanoSIMS 50 ion probe) for 3D chemical imaging of individual atmospheric particles without any sample pre-treatment, such as the sectioning of particles. Use of NanoSIMS depth profile analysis enables elemental mapping of particles with nanometer spatial resolution over a broad of range of particle sizes. We have used this technique to probe spatially resolved composition of ambient particles collected during a field campaign in Mexico City. Particles collected during this campaign have been extensively characterized in the past using other particle analysis techniques and hence offer a unique opportunity for exploring the utility of depth resolved chemical imaging in ambient particle research. Particles examined in this study include those collected during a pollution episode related to urban waste incineration as well as background particles from the same location prior to the episode. Particles from the pollution episode show substantial intra-particle compositional variability typical of particles resulting from multiple emission sources. In contrast, the background particles have relatively homogeneous compositions with enhanced presence of nitrogen, oxygen and chlorine at the particle surface. The observed surface enhancement of nitrogen and oxygen species is consistent with the presence of surface nitrates resulting from gas-particle heterogeneous interactions and is indicative of atmospheric ageing of the particles. The results presented here illustrate 3D characterization of ambient particles for insights into their chemical history.

  4. Time-resolved spatial phase measurements with 2-dimensional spectral interferometry

    NASA Astrophysics Data System (ADS)

    Childress, Colby; Planchon, Thomas; Amir, Wafa; Squier, Jeff A.; Durfee, Charles G.

    2007-03-01

    We are using 2-dimensional spectral interferometry for sensitive measurements of spatial phase distortions. The reference pulse and the time-delayed probe pulse are coincident on an imaging spectrometer, yielding spectral and spatial phase information. This technique offers the potential of higher sensitivity than traditional spatial interferometry since there are many fringes of data for each spatial point. We illustrate this technique with measurements of the thermal lensing profile in a cryogenically cooled Ti:sapphire amplifier crystal that is pumped by tens of watts of power from four frequency-doubled Nd:YLF lasers running at 1 kHz. By adjusting the relative delay of the probe and reference pulses, we characterize the thermal transients during and after the pump pulses. We compare the measured transient thermal profiles with those calculated with a finite-element model.

  5. Spatially Resolved Magnetic Field Structure in the Disk of a T Tauri Star

    NASA Astrophysics Data System (ADS)

    Stephens, Ian; Looney, Leslie; Kwon, Woojin; Fernandez Lopez, Manuel; Hughes, A. Meredith; Mundy, Lee G.; Crutcher, Richard; Li, Zhi-Yun; Rao, Ramprasad; Segura-Cox, Dominique

    2015-01-01

    The formation of disks around protostars is thought to be regulated through magnetic fields, and theoretical models suggest that the fractional polarization should be approximately 2-3%. However, resolved observations of disks in T Tauri stars have remained undetected and are constrained to have fractional polarization of less than 1%. With CARMA observations of HL Tau, we recently found the first detection of a resolved magnetic field about a T Tauri Star. While poloidal field components appear to be completely absent for HL Tau at the 80 AU scale, a purely toroidal field does not fit the observations well either, suggesting the system is more complicated than theoretically expected. Incoming ALMA observations of both HL Tau and Class 0 protostellar disks will help disentangle the true magnetic field morphology in the disks of protostars.

  6. Spatially resolved diffuse reflectance spectroscopy of two-layer turbid media by densely packed multi-pixel photodiode reflectance probe

    NASA Astrophysics Data System (ADS)

    Senlik, Ozlem; Greening, Gage; Muldoon, Timothy J.; Jokerst, Nan M.

    2016-03-01

    Spatially-resolved diffuse reflectance (SRDR) measurements provide photon path information, and enable layered tissue analysis. This paper presents experimental SRDR measurements on two-layer PDMS skin tissue-mimicking phantoms of varying top layer thicknesses, and bulk phantoms of varying optical properties using concentric multi-pixel photodiode array (CMPA) probes, and corresponding forward Monte Carlo simulations. The CMPA is the most densely packed semiconductor SRDR probe reported to date. Signal contrasts between the single layer phantom and bi-layer phantoms with varying top layer thicknesses are as high as 80%. The mean error between the Monte Carlo simulations and the experiment is less than 6.2 %.

  7. Spatially resolved quantitative magnetic order measurement in spinel CuCr{sub 2}S{sub 4} nanocrystals

    SciTech Connect

    Negi, D. S.; Loukya, B.; Datta, R.; Ramasamy, K.; Gupta, A.

    2015-05-04

    We have utilized spatially resolved high resolution electron energy loss spectroscopy to quantify the relative percentage of ferromagnetic order in the core and the surface regions of CuCr{sub 2}S{sub 4} nanoparticles with nanocube and nanocluster morphology. The organic capping layer is found to play a significant role in restoring magnetic order at the surface. The technique is based on recording the fine features of the Cr L{sub 3} absorption edge and matching them with the theoretical spectra. The nanoscale probing technique we have developed is quite versatile and can be extended to understand magnetic ordering in a number of nanodimensional magnetic materials.

  8. Characterization of spatially resolved high resolution x-ray spectrometers for high energy density physics and light source experiments

    SciTech Connect

    Hill, K. W. Bitter, M.; Delgado-Aparacio, L.; Efthimion, P.; Pablant, N. A.; Lu, J.; Beiersdorfer, P.; Chen, H.; Magee, E.

    2014-11-15

    A high resolution 1D imaging x-ray spectrometer concept comprising a spherically bent crystal and a 2D pixelated detector is being optimized for diagnostics of small sources such as high energy density physics (HEDP) and synchrotron radiation or x-ray free electron laser experiments. This instrument is used on tokamak experiments for Doppler measurements of ion temperature and plasma flow velocity profiles. Laboratory measurements demonstrate a resolving power, E/ΔE of order 10 000 and spatial resolution better than 10 μm. Initial tests of the high resolution instrument on HEDP plasmas are being performed.

  9. Fiber Bragg grating based spatially resolved characterization of flux-pinning-induced strain of disk-shaped bulk YBCO samples

    NASA Astrophysics Data System (ADS)

    Latka, Ines; Habisreuther, Tobias; Zeisberger, Matthias

    2009-07-01

    A new optical method for the characterization of magnetostrictive effects in bulk superconductors will be presented. Several of wavelength encoded fiber Bragg gratings can be inscribed in one fiber with small spatial distances, which gives the possibility to measure magnetostrictive effects spatially resolved. To demonstrate the performance, samples with Bragg grating arrays glued onto the surface of an YBCO disk where tested in a superconducting solenoid at temperatures of 60 K and magnetic inductances of 6.5 T. For the first time the radius position dependent strain and not only sum effects could be measured. It was stated that in the remnant state both, elongating and compressive strain, occur. This is in agreement with our simulations.

  10. Spatially Resolved Measurements of Laser Filamentation in Long Scale Length Underdense Plasmas with and without Beam Smoothing

    SciTech Connect

    Sarri, G.; Cecchetti, C. A.; Doria, D.; Borghesi, M.; Jung, R.; Willi, O.; Hobbs, P.; James, S.; Lockyear, J.; Stevenson, R. M.; Hoarty, D. J.

    2011-03-04

    The onset of filamentation, following the interaction of a relatively long ({tau}{sub L}{approx_equal}1 ns) and intense (I{sub L}{approx_equal}5x10{sup 14} W/cm{sup 2}) laser pulse with a neopentane filled gas bag target, has been experimentally studied via the proton radiography technique, in conditions of direct relevance to the indirect drive inertial confinement fusion scheme. The density gradients associated with filamentation onset have been spatially resolved yielding direct and unambiguous evidence of filament formation and quantitative information about the filamentation mechanism in agreement with previous theoretical modelings. Experimental data confirm that, once spatially smoothed laser beams are used, filamentation is not a relevant phenomenon during the heating laser beams propagation through typical hohlraum gas fills.

  11. Macroscopic and microscopic spatially-resolved analysis of food contaminants and constituents using laser-ablation electrospray ionization mass spectrometry imaging.

    PubMed

    Nielen, Michel W F; van Beek, Teris A

    2014-11-01

    Laser-ablation electrospray ionization (LAESI) mass spectrometry imaging (MSI) does not require very flat surfaces, high-precision sample preparation, or the addition of matrix. Because of these features, LAESI-MSI may be the method of choice for spatially-resolved food analysis. In this work, LAESI time-of-flight MSI was investigated for macroscopic and microscopic imaging of pesticides, mycotoxins, and plant metabolites on rose leaves, orange and lemon fruit, ergot bodies, cherry tomatoes, and maize kernels. Accurate mass ion-map data were acquired at sampling locations with an x-y center-to-center distance of 0.2-1.0 mm and were superimposed onto co-registered optical images. The spatially-resolved ion maps of pesticides on rose leaves suggest co-application of registered and banned pesticides. Ion maps of the fungicide imazalil reveal that this compound is only localized on the peel of citrus fruit. However, according to three-dimensional LAESI-MSI the penetration depth of imazalil into the peel has significant local variation. Ion maps of different plant alkaloids on ergot bodies from rye reveal co-localization in accordance with expectations. The feasibility of using untargeted MSI for food analysis was revealed by ion maps of plant metabolites in cherry tomatoes and maize-kernel slices. For tomatoes, traveling-wave ion mobility (TWIM) was used to discriminate between different lycoperoside glycoalkaloid isomers; for maize quadrupole time-of-flight tandem mass spectrometry (MS-MS) was successfully used to elucidate the structure of a localized unknown. It is envisaged that LAESI-MSI will contribute to future research in food science, agriforensics, and plant metabolomics. PMID:24961635

  12. Spatially resolved micro-absorption spectroscopy with a broadband source and confocal detection

    NASA Astrophysics Data System (ADS)

    Arora, Silki; Mauser, Jennifer; Chakrabarti, Debopam; Schulte, Alfons

    2015-11-01

    We present a novel approach to measure optical absorption spectra with spatial resolution at the micron scale. The setup combines a continuous white light excitation beam in transmission geometry with a confocal microscope. The spatial resolution is found to be better than 1.4 μm in the lateral and 3.6 μm in the axial direction. Employing multichannel detection the absorption spectrum of hemoglobin in a single red blood cell is measured on the timescale of seconds. Through measurements of the transmitted intensity in solutions in nanoliter quantities we establish that the absorbance varies linearly with concentration. Our setup enables the investigation of spatial variations in the optical density of small samples on the micron scale and can be applied to the study of biological assemblies at the single cell level, in optical diagnostics, and in micro-fluidics.

  13. Drought tolerance as a driver of tropical forest assembly: resolving spatial signatures for multiple processes.

    PubMed

    Bartlett, M K; Zhang, Y; Yang, J; Kreidler, N; Sun, S w; Lin, L; Hu, Y H; Cao, K F; Sack, L

    2016-02-01

    Spatial patterns in trait variation reflect underlying community assembly processes, allowing us to test hypotheses about their trait and environmental drivers by identifying the strongest correlates of characteristic spatial patterns. For 43 evergreen tree species (> 1 cm dbh) in a 20-ha seasonal tropical rainforest plot in Xishuangbanna, China, we compared the ability of drought-tolerance traits, other physiological traits, and commonly measured functional traits to predict the spatial patterns expected from the assembly processes of habitat associations, niche-overlap-based competition, and hierarchical competition. We distinguished the neighborhood-scale (0-20 m) patterns expected from competition from larger-scale habitat associations with a wavelet method. Species' drought tolerance and habitat variables related to soil water supply were strong drivers of habitat associations, and drought tolerance showed a significant spatial signal for influencing competition. Overall, the traits most strongly associated with habitat, as quantified using multivariate models, were leaf density, leaf turgor loss point (π(tlp); also known as the leaf wilting point), and stem hydraulic conductivity (r2 range for the best fit models = 0.27-0.36). At neighborhood scales, species spatial associations were positively correlated with similarity in π(tlp), consistent with predictions for hierarchical competition. Although the correlation between π(tlp) and interspecific spatial associations was weak (r2 < 0.01), this showed a persistent influence of drought tolerance on neighborhood interactions and community assembly. Quantifying the full impact of traits on competitive interactions in forests may require incorporating plasticity among individuals within species, especially among specific life stages, and moving beyond individual traits to integrate the impact of multiple traits on whole-plant performance and resource demand. PMID:27145624

  14. Spatially resolved dynamic structure factor of finite systems from molecular dynamics simulations

    SciTech Connect

    Raitza, Thomas; Roepke, Gerd; Reinholz, Heidi; Morozov, Igor

    2011-09-15

    The dynamical response of metallic clusters up to 10{sup 3} atoms is investigated using the restricted molecular dynamics simulations scheme. Exemplarily, a sodium like material is considered. Correlation functions are evaluated to investigate the spatial structure of collective electron excitations and the optical response of laser-excited clusters. In particular, the spectrum of bilocal correlation functions shows resonances representing different modes of collective excitations inside the nano plasma. The spatial structure, the resonance energy, and the width of the eigenmodes have been investigated for various values of electron density, temperature, cluster size, and ionization degree. Comparison with bulk properties is performed and the dispersion relation of collective excitations is discussed.

  15. Sub-nA spatially resolved conductivity profiling of surface and interface defects in ceria films

    DOE PAGESBeta

    Farrow, Tim; Yang, Nan; Doria, Sandra; Belianinov, Alex; Jesse, Stephen; Arruda, Thomas M.; Balestrino, Giuseppe; Kalinin, Sergei V.; Kumar, Amit

    2015-03-17

    Spatial variability of conductivity in ceria is explored using scanning probe microscopy with galvanostatic control. Ionically blocking electrodes are used to probe the conductivity under opposite polarities to reveal possible differences in the defect structure across a thin film of CeO2. Data suggest the existence of a large spatial inhomogeneity that could give rise to constant phase elements during standard electrochemical characterization, potentially affecting the overall conductivity of films on the macroscale. The approach discussed here can also be utilized for other mixed ionic electronic conductor systems including memristors and electroresistors, as well as physical systems such as ferroelectric tunnelingmore » barriers« less

  16. Sub-nA spatially resolved conductivity profiling of surface and interface defects in ceria films

    SciTech Connect

    Farrow, Tim; Yang, Nan; Doria, Sandra; Belianinov, Alex; Jesse, Stephen; Arruda, Thomas M.; Balestrino, Giuseppe; Kalinin, Sergei V.; Kumar, Amit

    2015-03-17

    Spatial variability of conductivity in ceria is explored using scanning probe microscopy with galvanostatic control. Ionically blocking electrodes are used to probe the conductivity under opposite polarities to reveal possible differences in the defect structure across a thin film of CeO2. Data suggest the existence of a large spatial inhomogeneity that could give rise to constant phase elements during standard electrochemical characterization, potentially affecting the overall conductivity of films on the macroscale. The approach discussed here can also be utilized for other mixed ionic electronic conductor systems including memristors and electroresistors, as well as physical systems such as ferroelectric tunneling barriers

  17. Spatially resolved Lyman-alpha emission from a virtual dwarf galaxy

    NASA Astrophysics Data System (ADS)

    Verhamme, Anne

    2015-02-01

    In the context of the first light of MUSE, Integral Field Unit (IFU) spectrograph of second generation installed recently at VLT, we compute mock IFU Lyman-alpha (lyα) observations of a virtual dwarf galaxy, to help understanding and interpreting forthcoming observations. This study is an extension of the work carried out in Verhamme et al. (2012), where we studied the spatially integrated lyα properties of a dwarf galaxy. With the same data, we now investigate the spatial variations of lyα spectra.

  18. Sub-nA spatially resolved conductivity profiling of surface and interface defects in ceria films

    SciTech Connect

    Farrow, Tim; Kumar, Amit; Yang, Nan; Doria, Sandra; Balestrino, Giuseppe; Belianinov, Alex; Jesse, Stephen; Kalinin, Sergei V.; Arruda, Thomas M.

    2015-03-01

    Spatial variability of conductivity in ceria is explored using scanning probe microscopy with galvanostatic control. Ionically blocking electrodes are used to probe the conductivity under opposite polarities to reveal possible differences in the defect structure across a thin film of CeO{sub 2}. Data suggest the existence of a large spatial inhomogeneity that could give rise to constant phase elements during standard electrochemical characterization, potentially affecting the overall conductivity of films on the macroscale. The approach discussed here can also be utilized for other mixed ionic electronic conductor systems including memristors and electroresistors, as well as physical systems such as ferroelectric tunneling barriers.

  19. VizieR Online Data Catalog: LARS VIII. Spatially resolved Halpha kinematics (Herenz+, 2016)

    NASA Astrophysics Data System (ADS)

    Herenz, E. C.; Gruyters, P.; Orlitova, I.; Hayes, M.; Ostlin, G.; Cannon, J. M.; Roth, M.; Bik, A.; Pardy, S.; Oti-Floranes, H.; Mas-Hesse, J. M.; Adamo, A.; Atek, H.; Duval, F.; Guaita, L.; Kunth, D.; Laursen, P.; Melinder, J.; Puschnig, J.; Rivera-Thorsen, T. E.; Schaerer, D.; Verhamme, A.

    2015-11-01

    The FITS files contain the reduced Calar-Alto 3.5m PMAS flux datacubes. Observations and datareduction are described in Sects. 2 and 3 of the paper. We also provide errorcubes and the resolving power maps that were used in our derivation of the Hα velocity fields. WCS information is included only in the fluxcubes. The cubes were registered to our HST imaging data, so the WCS information might not be correct in an absolute sense. Wavelengths are in air as measured, i.e. no barycentric correction is applied. (2 data files).

  20. Spatially resolved optical absorption spectroscopy of single- and few-layer MoS2 by hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Castellanos-Gomez, Andres; Quereda, Jorge; van der Meulen, Herko P.; Agraït, Nicolás; Rubio-Bollinger, Gabino

    2016-03-01

    The possibility of spatially resolving the optical properties of atomically thin materials is especially appealing as they can be modulated at the micro- and nanoscale by reducing their thickness, changing the doping level or applying a mechanical deformation. Therefore, optical spectroscopy techniques with high spatial resolution are necessary to get a deeper insight into the properties of two-dimensional (2D) materials. Here we study the optical absorption of single- and few-layer molybdenum disulfide (MoS2) in the spectral range from 1.24 eV to 3.22 eV (385 nm to 1000 nm) by developing a hyperspectral imaging technique that allows one to probe the optical properties with diffraction limited spatial resolution. We find hyperspectral imaging very suited to study indirect bandgap semiconductors, unlike photoluminescence which only provides high luminescence yield for direct gap semiconductors. Moreover, this work opens the door to study the spatial variation of the optical properties of other 2D systems, including non-semiconducting materials where scanning photoluminescence cannot be employed.

  1. Spatially resolved optical absorption spectroscopy of single- and few-layer MoS₂ by hyperspectral imaging.

    PubMed

    Castellanos-Gomez, Andres; Quereda, Jorge; van der Meulen, Herko P; Agraït, Nicolás; Rubio-Bollinger, Gabino

    2016-03-18

    The possibility of spatially resolving the optical properties of atomically thin materials is especially appealing as they can be modulated at the micro- and nanoscale by reducing their thickness, changing the doping level or applying a mechanical deformation. Therefore, optical spectroscopy techniques with high spatial resolution are necessary to get a deeper insight into the properties of two-dimensional (2D) materials. Here we study the optical absorption of single- and few-layer molybdenum disulfide (MoS2) in the spectral range from 1.24 eV to 3.22 eV (385 nm to 1000 nm) by developing a hyperspectral imaging technique that allows one to probe the optical properties with diffraction limited spatial resolution. We find hyperspectral imaging very suited to study indirect bandgap semiconductors, unlike photoluminescence which only provides high luminescence yield for direct gap semiconductors. Moreover, this work opens the door to study the spatial variation of the optical properties of other 2D systems, including non-semiconducting materials where scanning photoluminescence cannot be employed. PMID:26876671

  2. Velocity gradients in spatially resolved laser Doppler flowmetry and dynamic light scattering with confocal and coherence gating

    NASA Astrophysics Data System (ADS)

    Uribe-Patarroyo, Néstor; Bouma, Brett E.

    2016-08-01

    Dynamic light scattering (DLS) is widely used to characterize diffusive motion to obtain precise information on colloidal suspensions by calculating the autocorrelation function of the signal from a heterodyne optical system. DLS can also be used to determine the flow velocity field in systems that exhibit mass transport by incorporating the effects of the deterministic motion of scatterers on the autocorrelation function, a technique commonly known as laser Doppler flowmetry. DLS measurements can be localized with confocal and coherence gating techniques such as confocal microscopy and optical coherence tomography, thereby enabling the determination of the spatially resolved velocity field in three dimensions. It has been thought that spatially resolved DLS can determine the axial velocity as well as the lateral speed in a single measurement. We demonstrate, however, that gradients in the axial velocity of scatterers exert a fundamental influence on the autocorrelation function even in well-behaved, nonturbulent flow. By obtaining the explicit functional relation between axial-velocity gradients and the autocorrelation function, we show that the velocity field and its derivatives are intimately related and their contributions cannot be separated. Therefore, a single DLS measurement cannot univocally determine the velocity field. Our extended theoretical model was found to be in good agreement with experimental measurements.

  3. In situ spatially and temporally resolved measurements of salt concentration between charging porous electrodes for desalination by capacitive deionization.

    PubMed

    Suss, Matthew E; Biesheuvel, P M; Baumann, Theodore F; Stadermann, Michael; Santiago, Juan G

    2014-01-01

    Capacitive deionization (CDI) is an emerging water desalination technique. In CDI, pairs of porous electrode capacitors are electrically charged to remove salt from brackish water present between the electrodes. We here present a novel experimental technique allowing measurement of spatially and temporally resolved salt concentration between the CDI electrodes. Our technique measures the local fluorescence intensity of a neutrally charged fluorescent probe which is collisionally quenched by chloride ions. To our knowledge, our system is the first to measure in situ and spatially resolved chloride concentration in a laboratory CDI cell. We here demonstrate good agreement between our dynamic measurements of salt concentration in a charging, millimeter-scale CDI system to the results of a modified Donnan porous electrode transport model. Further, we utilize our dynamic measurements to demonstrate that salt removal between our charging CDI electrodes occurs on a longer time scale than the capacitive charging time scales of our CDI cell. Compared to typical measurements of CDI system performance (namely, measurements of outflow ionic conductivity), our technique can enable more advanced and better-controlled studies of ion transport in CDI systems, which can potentially catalyze future performance improvements. PMID:24433022

  4. Diagnosing the plasma nonuniformity in an iron opacity experiment by spatially resolved Al 1s-2p absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Xiaoding, Zhang; Jiyan, Zhang; Yang, Zhao; Gang, Xiong; Bin, Zhao; Guohong, Yang; Jian, Zheng; Jiamin, Yang

    2012-12-01

    Generating a well-characterized hot-dense sample is of great importance to high quality opacity measurements. In this paper, we report on an experimental investigation of the plasma nonuniformity in a radiatively heated iron opacity sample by spatially resolved Al 1s-2p absorption spectroscopy. The iron sample was tamped by plastic at both sides and was heated by thermal x-ray radiation generated in a gold Hohlraum, and an Al layer attached to it was used as a tracer for temperature diagnosis. Spatially resolved 1s-2p transition absorption spectra of the Al tracer were measured by the technique of point-projection-spectroscopy, and temperatures in the sample were obtained by comparing the measured spectra with detailed-term-accounting model calculations, with the density of the sample deduced using a combination of side-on radiography and radiative hydrodynamic simulation. The results showed the existence of axial temperature nonuniformity in the sample, and these temperature variations have been used to explain the shift of iron 2p-3d transition absorption feature along the axial direction of the Hohlraum used to heat the sample successfully.

  5. Velocity gradients in spatially resolved laser Doppler flowmetry and dynamic light scattering with confocal and coherence gating.

    PubMed

    Uribe-Patarroyo, Néstor; Bouma, Brett E

    2016-08-01

    Dynamic light scattering (DLS) is widely used to characterize diffusive motion to obtain precise information on colloidal suspensions by calculating the autocorrelation function of the signal from a heterodyne optical system. DLS can also be used to determine the flow velocity field in systems that exhibit mass transport by incorporating the effects of the deterministic motion of scatterers on the autocorrelation function, a technique commonly known as laser Doppler flowmetry. DLS measurements can be localized with confocal and coherence gating techniques such as confocal microscopy and optical coherence tomography, thereby enabling the determination of the spatially resolved velocity field in three dimensions. It has been thought that spatially resolved DLS can determine the axial velocity as well as the lateral speed in a single measurement. We demonstrate, however, that gradients in the axial velocity of scatterers exert a fundamental influence on the autocorrelation function even in well-behaved, nonturbulent flow. By obtaining the explicit functional relation between axial-velocity gradients and the autocorrelation function, we show that the velocity field and its derivatives are intimately related and their contributions cannot be separated. Therefore, a single DLS measurement cannot univocally determine the velocity field. Our extended theoretical model was found to be in good agreement with experimental measurements. PMID:27627357

  6. Diagnosing the plasma nonuniformity in an iron opacity experiment by spatially resolved Al 1s-2p absorption spectroscopy

    SciTech Connect

    Zhang Xiaoding; Zhang Jiyan; Zhao Yang; Xiong Gang; Yang Guohong; Yang Jiamin; Zhao Bin; Zheng Jian

    2012-12-15

    Generating a well-characterized hot-dense sample is of great importance to high quality opacity measurements. In this paper, we report on an experimental investigation of the plasma nonuniformity in a radiatively heated iron opacity sample by spatially resolved Al 1s-2p absorption spectroscopy. The iron sample was tamped by plastic at both sides and was heated by thermal x-ray radiation generated in a gold Hohlraum, and an Al layer attached to it was used as a tracer for temperature diagnosis. Spatially resolved 1s-2p transition absorption spectra of the Al tracer were measured by the technique of point-projection-spectroscopy, and temperatures in the sample were obtained by comparing the measured spectra with detailed-term-accounting model calculations, with the density of the sample deduced using a combination of side-on radiography and radiative hydrodynamic simulation. The results showed the existence of axial temperature nonuniformity in the sample, and these temperature variations have been used to explain the shift of iron 2p-3d transition absorption feature along the axial direction of the Hohlraum used to heat the sample successfully.

  7. Quantifying Seagrass Light Requirements Using an Algorithm to Spatially Resolve Depth of Colonization

    EPA Science Inventory

    The maximum depth of colonization (Zc) is a useful measure of seagrass growth that describes response to light attenuation in the water column. However, lack of standardization among methods for estimating Zc has limited the description of habitat requirements at spatial scales m...

  8. Spatially Resolved Chemical Imaging for Biosignature Analysis: Terrestrial and Extraterrestrial Examples

    NASA Astrophysics Data System (ADS)

    Bhartia, R.; Wanger, G.; Orphan, V. J.; Fries, M.; Rowe, A. R.; Nealson, K. H.; Abbey, W. J.; DeFlores, L. P.; Beegle, L. W.

    2014-12-01

    Detection of in situ biosignatures on terrestrial and planetary missions is becoming increasingly more important. Missions that target the Earth's deep biosphere, Mars, moons of Jupiter (including Europa), moons of Saturn (Titan and Enceladus), and small bodies such as asteroids or comets require methods that enable detection of materials for both in-situ analysis that preserve context and as a means to select high priority sample for return to Earth. In situ instrumentation for biosignature detection spans a wide range of analytical and spectroscopic methods that capitalize on amino acid distribution, chirality, lipid composition, isotopic fractionation, or textures that persist in the environment. Many of the existing analytical instruments are bulk analysis methods and while highly sensitive, these require sample acquisition and sample processing. However, by combining with triaging spectroscopic methods, biosignatures can be targeted on a surface and preserve spatial context (including mineralogy, textures, and organic distribution). To provide spatially correlated chemical analysis at multiple spatial scales (meters to microns) we have employed a dual spectroscopic approach that capitalizes on high sensitivity deep UV native fluorescence detection and high specificity deep UV Raman analysis.. Recently selected as a payload on the Mars 2020 mission, SHERLOC incorporates these optical methods for potential biosignatures detection on Mars. We present data from both Earth analogs that operate as our only examples known biosignatures and meteorite samples that provide an example of abiotic organic formation, and demonstrate how provenance effects the spatial distribution and composition of organics.

  9. A comparative analysis of two highly spatially resolved European atmospheric emission inventories

    NASA Astrophysics Data System (ADS)

    Ferreira, J.; Guevara, M.; Baldasano, J. M.; Tchepel, O.; Schaap, M.; Miranda, A. I.; Borrego, C.

    2013-08-01

    A reliable emissions inventory is highly important for air quality modelling applications, especially at regional or local scales, which require high resolutions. Consequently, higher resolution emission inventories have been developed that are suitable for regional air quality modelling. This research performs an inter-comparative analysis of different spatial disaggregation methodologies of atmospheric emission inventories. This study is based on two different European emission inventories with different spatial resolutions: 1) the EMEP (European Monitoring and Evaluation Programme) inventory and 2) an emission inventory developed by the TNO (Netherlands Organisation for Applied Scientific Research). These two emission inventories were converted into three distinct gridded emission datasets as follows: (i) the EMEP emission inventory was disaggregated by area (EMEParea) and (ii) following a more complex methodology (HERMES-DIS - High-Elective Resolution Modelling Emissions System - DISaggregation module) to understand and evaluate the influence of different disaggregation methods; and (iii) the TNO gridded emissions, which are based on different emission data sources and different disaggregation methods. A predefined common grid with a spatial resolution of 12 × 12 km2 was used to compare the three datasets spatially. The inter-comparative analysis was performed by source sector (SNAP - Selected Nomenclature for Air Pollution) with emission totals for selected pollutants. It included the computation of difference maps (to focus on the spatial variability of emission differences) and a linear regression analysis to calculate the coefficients of determination and to quantitatively measure differences. From the spatial analysis, greater differences were found for residential/commercial combustion (SNAP02), solvent use (SNAP06) and road transport (SNAP07). These findings were related to the different spatial disaggregation that was conducted by the TNO and HERMES

  10. Accurate optical wavefront reconstruction based on reciprocity of an optical path using low resolution spatial light modulators

    NASA Astrophysics Data System (ADS)

    Li, Zhiyang

    2010-10-01

    A method for high precision optical wavefront reconstruction using low resolution spatial light modulators (SLMs) was proposed. It utilizes an adiabatic waveguide taper consisting of a plurality of single-mode waveguides to decompose an incident light field into simple fundamental modes of the single-mode waveguides. By digital generation of the conjugate fields of those simple fundamental modes a field proportional to the original incident light field might be reconstructed accurately based on reciprocity. Devices based on the method using transparent and reflective SLMs possess no aberration like that of a conventional optic lens and are able to achieve diffraction limited resolution. Specifically on the surface of the narrow end of a taper a resolution much higher than half of the wavelength is attainable. The device may work in linear mode and possesses unlimited theoretical 3D space-bandwidth product (SBP). The SBP of a real device is limited by the accuracy of SLMs. A pair of 8-bit SLMs with 1000 × 1000 = 10 6 pixels could provide a SBP of about 5 × 10 4. The SBP may expand by 16 times if 10-bit SLMs with the same number of pixels are employed or 16 successive frames are used to display one scene. The device might be used as high precision optical tweezers, or employed for continuous or discrete real-time 3D display, 3D measurement, machine vision, etc.

  11. In pursuit of an accurate spatial and temporal model of biomolecules at the atomistic level: a perspective on computer simulation

    SciTech Connect

    Gray, Alan; Harlen, Oliver G.; Harris, Sarah A.; Khalid, Syma; Leung, Yuk Ming; Lonsdale, Richard; Mulholland, Adrian J.; Pearson, Arwen R.; Read, Daniel J.; Richardson, Robin A.

    2015-01-01

    The current computational techniques available for biomolecular simulation are described, and the successes and limitations of each with reference to the experimental biophysical methods that they complement are presented. Despite huge advances in the computational techniques available for simulating biomolecules at the quantum-mechanical, atomistic and coarse-grained levels, there is still a widespread perception amongst the experimental community that these calculations are highly specialist and are not generally applicable by researchers outside the theoretical community. In this article, the successes and limitations of biomolecular simulation and the further developments that are likely in the near future are discussed. A brief overview is also provided of the experimental biophysical methods that are commonly used to probe biomolecular structure and dynamics, and the accuracy of the information that can be obtained from each is compared with that from modelling. It is concluded that progress towards an accurate spatial and temporal model of biomacromolecules requires a combination of all of these biophysical techniques, both experimental and computational.

  12. Global and Spatially Resolved Photometric Properties of the Nucleus of Comet 67P/C-G from OSIRIS Images

    NASA Astrophysics Data System (ADS)

    Lamy, P.

    2014-04-01

    photometric properties of the nucleus of comet 67P/C-G, albedo, phase function and spectral reflectivity and compare with previous results obtained with the Hubble and Spitzer space telescopes [2, 3, 4]. Then observations during the approach and first bound orbits in July-August 2014 will allow mapping the surface of the nucleus with OSIRIS at a scale of up to 1 meter per pixel. The images will be used to reconstruct the 3D surface of the nucleus at highresolution allowing separating true photometric variations from topographic effects. We will present results on the spatially resolved photometric properties of the nucleus based on a novel method developed in the space of the facets representing the three-dimensional shape of the body. This method successfully implemented in the cases of the nucleus of comet 9P/Tempel 2 and of asteroid (2867) Steins [5] has the advantage of automatically tracking the same local surface element on a series of images. The analysis will then proceed with the determination of the global Hapke and other standard photometric parameters as well as their two-dimensional variations across the surface. This allows defining, in the body-fixed reference frame, ``high residual regions'' (HRRs) which correspond to significant relative differences between the observed and modeled photometric parameters such as the singlescattering albedo (SSA), the mean roughness slope angle, and the reflectivity gradient. Of particular interest will be the search for ice patches and possible mineralogical differences resulting from the past activity of the comet.

  13. Research Update: Spatially resolved mapping of electronic structure on atomic level by multivariate statistical analysis

    NASA Astrophysics Data System (ADS)

    Belianinov, Alex; Ganesh, Panchapakesan; Lin, Wenzhi; Sales, Brian C.; Sefat, Athena S.; Jesse, Stephen; Pan, Minghu; Kalinin, Sergei V.

    2014-12-01

    Atomic level spatial variability of electronic structure in Fe-based superconductor FeTe0.55Se0.45 (Tc = 15 K) is explored using current-imaging tunneling-spectroscopy. Multivariate statistical analysis of the data differentiates regions of dissimilar electronic behavior that can be identified with the segregation of chalcogen atoms, as well as boundaries between terminations and near neighbor interactions. Subsequent clustering analysis allows identification of the spatial localization of these dissimilar regions. Similar statistical analysis of modeled calculated density of states of chemically inhomogeneous FeTe1-xSex structures further confirms that the two types of chalcogens, i.e., Te and Se, can be identified by their electronic signature and differentiated by their local chemical environment. This approach allows detailed chemical discrimination of the scanning tunneling microscopy data including separation of atomic identities, proximity, and local configuration effects and can be universally applicable to chemically and electronically inhomogeneous surfaces.

  14. Spatially resolved ultrasonic attenuation in resistance spot welds: implications for nondestructive testing.

    PubMed

    Mozurkewich, George; Ghaffari, Bita; Potter, Timothy J

    2008-09-01

    Spatial variation of ultrasonic attenuation and velocity has been measured in plane parallel specimens extracted from resistance spot welds. In a strong weld, attenuation is larger in the nugget than in the parent material, and the region of increased attenuation is surrounded by a ring of decreased attenuation. In the center of a stick weld, attenuation is even larger than in a strong weld, and the low-attenuation ring is absent. These spatial variations are interpreted in terms of differences in grain size and martensite formation. Measured frequency dependences indicate the presence of an additional attenuation mechanism besides grain scattering. The observed attenuations do not vary as commonly presumed with weld quality, suggesting that the common practice of using ultrasonic attenuation to indicate weld quality is not a reliable methodology. PMID:18325561

  15. Research Update: Spatially resolved mapping of electronic structure on atomic level by multivariate statistical analysis

    SciTech Connect

    Belianinov, Alex; Panchapakesan, G.; Lin, Wenzhi; Sales, Brian C.; Sefat, Athena Safa; Jesse, Stephen; Pan, Minghu; Kalinin, Sergei V.

    2014-12-02

    Atomic level spatial variability of electronic structure in Fe-based superconductor FeTe0.55Se0.45 (Tc = 15 K) is explored using current-imaging tunneling-spectroscopy. Multivariate statistical analysis of the data differentiates regions of dissimilar electronic behavior that can be identified with the segregation of chalcogen atoms, as well as boundaries between terminations and near neighbor interactions. Subsequent clustering analysis allows identification of the spatial localization of these dissimilar regions. Similar statistical analysis of modeled calculated density of states of chemically inhomogeneous FeTe1 x Sex structures further confirms that the two types of chalcogens, i.e., Te and Se, can be identified by their electronic signature and differentiated by their local chemical environment. This approach allows detailed chemical discrimination of the scanning tunneling microscopy data including separation of atomic identities, proximity, and local configuration effects and can be universally applicable to chemically and electronically inhomogeneous surfaces.

  16. Spatially Resolved H2 Emission In The GG Tau A Binary System

    NASA Astrophysics Data System (ADS)

    Bary, Jeffrey S.; Beck, T. L.; Dutrey, A.; Guilloteau, S.; Pietu, V.

    2012-01-01

    We present a high-resolution image of molecular hydrogen emission from the GG Tau A binary system. Using NIFS+AO on Gemini North to achieve 0.1" resolution, we clearly resolve the emitting gas to be located within the unstable region between the stellar cores and the circumbinary ring. The brightest arc of H2 emission observed to the northeast of the companions closely aligns with the location of a accretion "streamer" suggested by the high resolution millimeter observations presented in Pietu et al. 2011. The proximity of the H2 emission to the infalling streamer strongly suggests that the H2 emission is the result of a shocked gas residing in the orbital environment of the stellar companions. Near-infrared H2 line ratios predict an excitation temperature on the order of 1700 K and are compared to standard shock models.

  17. Spatially Resolved Synthetic Spectra from 2D Simulations of Stainless Steel Wire Array Implosions

    SciTech Connect

    Clark, R. W.; Giuliani, J. L.; Thornhill, J. W.; Chong, Y. K.; Dasgupta, A.; Davis, J.

    2009-01-21

    A 2D radiation MHD model has been developed to investigate stainless steel wire array implosion experiments on the Z and refurbished Z machines. This model incorporates within the Mach2 MHD code a self-consistent calculation of the non-LTE kinetics and ray trace based radiation transport. Such a method is necessary in order to account for opacity effects in conjunction with ionization kinetics of K-shell emitting plasmas. Here the model is used to investigate multi-dimensional effects of stainless steel wire implosions. In particular, we are developing techniques to produce non-LTE, axially and/or radially resolved synthetic spectra based upon snapshots of our 2D simulations. Comparisons between experimental spectra and these synthetic spectra will allow us to better determine the state of the experimental pinches.

  18. Spatially-resolved molecular Quantum Dots at the Surface of a Gated Graphene Device

    NASA Astrophysics Data System (ADS)

    Tsai, Hsin-Zon; Wickenburg, Sebastian; Lu, Jiong; Omrani, Arash A.; Coh, Sinisa; Jung, Han Sae; Wong, Dillon; Lischner, Johannes; Khajeh, Ramin; Riss, Alexander; Bradley, Aaron J.; Piatti, Erik; Zettl, Alex; Louie, Steven G.; Cohen, Marvin L.; Crommie, Michael F.

    2015-03-01

    The ability to modify the electronic properties of monolayer graphene via charge-donating or charge-accepting molecules creates new opportunities for fabricating nano-scale hybrid devices. Understanding the charge transfer process at the single molecule level is essential for tuning the electronic and magnetic characteristics of such hybrid devices. We have used scanning tunneling microscopy (STM) to locally probe how different molecular assemblies (including single molecules, molecular chains, and 2D molecular islands) exchange charge with a graphene substrate as the device backgate voltage is varied. Different molecular configurations exhibit substantially different charging behavior - some are permanently charged while others can be controllably ionized using the device backgate. Electrostatic interactions lead to charge heterogeneity at the molecular level. Single-chemical-bond-resolved atomic force microscopy allows us to correlate chemical structure and adsorption geometry of the molecules with their electronic properties.

  19. Spatially resolved electrochemistry in ionic liquids: surface structure effects on triiodide reduction at platinum electrodes.

    PubMed

    Aaronson, Barak D B; Lai, Stanley C S; Unwin, Patrick R

    2014-02-25

    Understanding the relationship between electrochemical activity and electrode structure is vital for improving the efficiency of dye-sensitized solar cells. Here, the reduction of triiodide to iodide in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) room temperature ionic liquid (RTIL) is investigated on polycrystalline platinum using scanning electrochemical cell microscopy (SECCM) and correlated to the crystallographic orientation from electron backscatter diffraction (EBSD). Although the rate determining step in all grains was the first electron transfer, significant grain-dependent variations in activity were revealed, with grains with a dominant (110) crystallographic character exhibiting higher catalytic activity compared to those with a major (100) orientation. The SECCM technique is demonstrated to resolve heterogeneity in activity, highlighting that methods incorporating polycrystalline electrodes miss vital details for understanding and optimizing electrocatalysts. An additional advantage of the SECCM over single-crystal techniques is its ability to probe high index facets. PMID:24479903

  20. Spatial resolving power and spectral sensitivity of the saltwater crocodile, Crocodylus porosus, and the freshwater crocodile, Crocodylus johnstoni.

    PubMed

    Nagloo, Nicolas; Collin, Shaun P; Hemmi, Jan M; Hart, Nathan S

    2016-05-01

    Crocodilians are apex amphibious predators that occupy a range of tropical habitats. In this study, we examined whether their semi-aquatic lifestyle and ambush hunting mode are reflected in specific adaptations in the peripheral visual system. Design-based stereology and microspectrophotometry were used to assess spatial resolving power and spectral sensitivity of saltwater (Crocodylus porosus) and freshwater crocodiles (Crocodylus johnstoni). Both species possess a foveal streak that spans the naso-temporal axis and mediates high spatial acuity across the central visual field. The saltwater crocodile and freshwater crocodile have a peak spatial resolving power of 8.8 and 8.0 cycles deg(-1), respectively. Measurement of the outer segment dimensions and spectral absorbance revealed five distinct photoreceptor types consisting of three single cones, one twin cone and a rod. The three single cones (saltwater/freshwater crocodile) are violet (424/426 nm λmax), green (502/510 nm λmax) and red (546/554 nm λmax) sensitive, indicating the potential for trichromatic colour vision. The visual pigments of both members of the twin cones have the same λmax as the red-sensitive single cone and the rod has a λmax at 503/510 nm (saltwater/freshwater). The λmax values of all types of visual pigment occur at longer wavelengths in the freshwater crocodile compared with the saltwater crocodile. Given that there is a greater abundance of long wavelength light in freshwater compared with a saltwater environment, the photoreceptors would be more effective at detecting light in their respective habitats. This suggests that the visual systems of both species are adapted to the photic conditions of their respective ecological niche. PMID:27208035

  1. Polarized and spatially resolved Raman scattering from composition-graded wurtzite InGaAs nanowires

    NASA Astrophysics Data System (ADS)

    Kim, H.; Rho, H.; Lee, E. H.; Song, J. D.

    2016-05-01

    We report Raman scattering from wurtzite single-crystalline InGaAs nanowires (NWs) to probe optical phonon behaviors associated with spatial grading in alloy composition along the NW length. Polarized Raman spectra revealed several optical phonons and their scattering symmetries: (i) InAs-like A 1(LO) and A 1(TO) phonons and (ii) GaAs-like A 1(LO), A 1(TO), and E 2(high) phonons. In addition, strong anisotropic behavior was observed in the Raman tensor elements of the A 1(TO) phonon mode. Interestingly, a spatial mapping of the GaAs-like A 1(TO) phonon along the NW length direction showed a systematic increase in energy from the NW top (~255 cm‑1) to the midpoint (~263 cm‑1), indicating an increase in the Ga mole fraction from about 0.5 to about 0.8. Further toward the NW bottom, the GaAs-like A 1(TO) phonon energy saturated to the peak value at about 264 cm‑1. In the upper half of the NW, the phonon linewidths broadened significantly due to the spatial grading in In/Ga composition along the NW length. When the composition grading was negligible in the bottom half of the NW, the spectral widths were considerably narrowed. The GaAs-like E 2(high) phonon showed similar variations in both energy and spectral width along the NW length.

  2. Spatially Resolved Spectroscopy of Submillimeter Galaxies at z ≃ 2

    NASA Astrophysics Data System (ADS)

    Olivares, V.; Treister, E.; Privon, G. C.; Alaghband-Zadeh, S.; Casey, Caitlin M.; Schawinski, K.; Kurczynski, P.; Gawiser, E.; Nagar, N.; Chapman, S.; Bauer, F. E.; Sanders, D.

    2016-08-01

    We present near-infrared integral-field spectroscopic observations targeting Hα in eight submillimeter galaxies (SMGs) at z = 1.3–2.5 using the Very Large Telescope/Spectrograph for Integral Field Observations in the Near Infrared, obtaining significant detections for six of them. The star formation rates derived from the Hα emission are ˜100 M ⊙ yr‑1, which account for only ˜20%–30% of the infrared-derived values, thus suggesting that these systems are very dusty. Two of these systems present [N ii]/Hα ratios indicative of the presence of an active galactic nucleus. We mapped the spatial distribution and kinematics of the star-forming regions in these galaxies on kiloparsec scales. In general, the Hα morphologies tend to be highly irregular and/or clumpy, showing spatial extents of ˜3–11 kpc. We find evidence for significant spatial offsets, of ˜0.″1–0.″4 or 1.2–3.4 kpc, between the Hα and the continuum emission in three of the sources. Performing a kinemetry analysis, we conclude that the majority of the sample is not consistent with disk-like rotation-dominated kinematics. Instead, they tend to show irregular and/or clumpy and turbulent velocity and velocity dispersion fields. This can be interpreted as evidence for a scenario in which these extreme star formation episodes are triggered by galaxy–galaxy interactions and major mergers. In contrast to recent results for SMGs, these sources appear to follow the same relations between gas and star-forming rate densities as less luminous and/or normal star-forming galaxies. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program IDs 088.A-0452 and 090.A-0464.

  3. Spatially Resolved Spectroscopy of Submillimeter Galaxies at z ≃ 2

    NASA Astrophysics Data System (ADS)

    Olivares, V.; Treister, E.; Privon, G. C.; Alaghband-Zadeh, S.; Casey, Caitlin M.; Schawinski, K.; Kurczynski, P.; Gawiser, E.; Nagar, N.; Chapman, S.; Bauer, F. E.; Sanders, D.

    2016-08-01

    We present near-infrared integral-field spectroscopic observations targeting Hα in eight submillimeter galaxies (SMGs) at z = 1.3–2.5 using the Very Large Telescope/Spectrograph for Integral Field Observations in the Near Infrared, obtaining significant detections for six of them. The star formation rates derived from the Hα emission are ∼100 M ⊙ yr‑1, which account for only ∼20%–30% of the infrared-derived values, thus suggesting that these systems are very dusty. Two of these systems present [N ii]/Hα ratios indicative of the presence of an active galactic nucleus. We mapped the spatial distribution and kinematics of the star-forming regions in these galaxies on kiloparsec scales. In general, the Hα morphologies tend to be highly irregular and/or clumpy, showing spatial extents of ∼3–11 kpc. We find evidence for significant spatial offsets, of ∼0.″1–0.″4 or 1.2–3.4 kpc, between the Hα and the continuum emission in three of the sources. Performing a kinemetry analysis, we conclude that the majority of the sample is not consistent with disk-like rotation-dominated kinematics. Instead, they tend to show irregular and/or clumpy and turbulent velocity and velocity dispersion fields. This can be interpreted as evidence for a scenario in which these extreme star formation episodes are triggered by galaxy–galaxy interactions and major mergers. In contrast to recent results for SMGs, these sources appear to follow the same relations between gas and star-forming rate densities as less luminous and/or normal star-forming galaxies. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program IDs 088.A-0452 and 090.A-0464.

  4. Measurements of Spatially Resolved Velocity Variations in Shock Compressed Heterogeneous Materials Using a Line-Imaging Velocity Interferometer

    SciTech Connect

    ASAY,JAMES R.; CHHABILDAS,LALIT C.; KNUDSON,MARCUS D.; TROTT,WAYNE M.

    1999-09-01

    Relatively straightforward changes in the optical design of a conventional optically recording velocity interferometer system (ORVIS) can be used to produce a line-imaging velocity interferometer wherein both temporal and spatial resolution can be adjusted over a wide range. As a result line-imaging ORVIS can be tailored to a variety of specific applications involving dynamic deformation of heterogeneous materials as required by the characteristic length scale of these materials (ranging from a few {micro}m for ferroelectric ceramics to a few mm for concrete). A line-imaging ORVIS has been successfully interfaced to the target chamber of a compressed gas gun driver and fielded on numerous tests in combination with simultaneous measurements using a dual delay-leg, ''push-pull'' VISAR system. These tests include shock loading of glass-reinforced polyester composites, foam reverberation experiments (measurements at the free surface of a thin aluminum plate impacted by foam), and measurements of dispersive velocity in a shock-loaded explosive simulant (sugar). Comparison of detailed spatially-resolved material response to the spatially averaged VISAR measurements will be discussed.

  5. Spatially Resolved Observation of Dipole-Dipole Interaction between Rydberg Atoms

    SciTech Connect

    Ditzhuijzen, C. S. E. van; Noordam, L. D.; Heuvell, H. B. van Linden van den; Koenderink, A. F.; Hernandez, J. V.; Robicheaux, F.

    2008-06-20

    We have observed resonant energy transfer between cold Rydberg atoms in spatially separated cylinders. Resonant dipole-dipole coupling excites the 49s atoms in one cylinder to the 49p state while the 41d atoms in the second cylinder are transferred down to the 42p state. We have measured the production of the 49p state as a function of separation of the cylinders (0-80 {mu}m) and the interaction time (0-25 {mu}s). In addition, we measured the width of the electric field resonances. A full many-body quantum calculation reproduces the main features of the experiments.

  6. The beauty of resolution: The SN Ib factory NGC 2770 spatially resolved

    NASA Astrophysics Data System (ADS)

    Thöne, C. C.; Christensen, L.; Gorosabel, J.; de Ugarte Postigo, A.

    2015-02-01

    The late-type spiral NGC 2770 hosted 3 Type Ib supernovae (SNe) in or next to star-forming regions in its outer spiral arms. We study the properties of the SN sites and the galaxy at different spatial resolutions to infer propeties of the SN progenitors and the SF history of the galaxy. Several 3D techniques are used and, for the first time, we present images of metallicity, shocks and stellar population ages from OSIRIS/GTC imaging with tunable narrowband filters.

  7. Spatially resolved measurements of two-dimensional turbulent structures in DIII-D plasmas

    NASA Astrophysics Data System (ADS)

    Zemedkun, S. E.; Che, S.; Chen, Y.; Domier, C. W.; Luhmann, N. C.; Munsat, T.; Parker, S. E.; Tobias, B.; Wan, W.; Yu, L.

    2015-12-01

    Two-dimensional observations of spatially coherent electron temperature fluctuations at drift-wave scales (k ˜ 1 cm-1) have been made using the electron cyclotron emission imaging diagnostic on the DIII-D tokamak. These measurements enable the extraction of spectral properties, including poloidal dispersion relations. Temperature fluctuation levels are found to be Te ˜/⟨Te⟩=1.2 % , and the phase velocity of the fluctuations is found to be constant across frequencies, consistent with modes having real frequencies low compared to the rotation-induced Doppler shifts. Comparisons with radially global linear gyrokinetic simulations suggest that the observed modes may be trapped electron modes.

  8. Spatially resolved X-ray line spectroscopy of Tycho's supernova remnant

    NASA Technical Reports Server (NTRS)

    Gotthelg, Eric V.; Hwang, Una

    1996-01-01

    Narrow band X-ray images of Tycho's supernova remnant, acquired with the solid-state spectrometer onboard the Advanced Satellite for Cosmology and Astrophysics (ASCA), are presented. The remnant is mapped in several prominent emission lines and in the 1.4 keV to 1.7 keV and 4 keV to 6 keV continua. A spatial resolution of approximately 0.5 min was obtained. No significant correlation was found for Tycho between the X-ray 4 keV to 6 keV continuum and the radio morphology.

  9. Research Update: Spatially resolved mapping of electronic structure on atomic level by multivariate statistical analysis

    SciTech Connect

    Belianinov, Alex Ganesh, Panchapakesan; Lin, Wenzhi; Jesse, Stephen; Pan, Minghu; Kalinin, Sergei V.; Sales, Brian C.; Sefat, Athena S.

    2014-12-01

    Atomic level spatial variability of electronic structure in Fe-based superconductor FeTe{sub 0.55}Se{sub 0.45} (T{sub c} = 15 K) is explored using current-imaging tunneling-spectroscopy. Multivariate statistical analysis of the data differentiates regions of dissimilar electronic behavior that can be identified with the segregation of chalcogen atoms, as well as boundaries between terminations and near neighbor interactions. Subsequent clustering analysis allows identification of the spatial localization of these dissimilar regions. Similar statistical analysis of modeled calculated density of states of chemically inhomogeneous FeTe{sub 1−x}Se{sub x} structures further confirms that the two types of chalcogens, i.e., Te and Se, can be identified by their electronic signature and differentiated by their local chemical environment. This approach allows detailed chemical discrimination of the scanning tunneling microscopy data including separation of atomic identities, proximity, and local configuration effects and can be universally applicable to chemically and electronically inhomogeneous surfaces.

  10. Research Update: Spatially resolved mapping of electronic structure on atomic level by multivariate statistical analysis

    DOE PAGESBeta

    Belianinov, Alex; Panchapakesan, G.; Lin, Wenzhi; Sales, Brian C.; Sefat, Athena Safa; Jesse, Stephen; Pan, Minghu; Kalinin, Sergei V.

    2014-12-02

    Atomic level spatial variability of electronic structure in Fe-based superconductor FeTe0.55Se0.45 (Tc = 15 K) is explored using current-imaging tunneling-spectroscopy. Multivariate statistical analysis of the data differentiates regions of dissimilar electronic behavior that can be identified with the segregation of chalcogen atoms, as well as boundaries between terminations and near neighbor interactions. Subsequent clustering analysis allows identification of the spatial localization of these dissimilar regions. Similar statistical analysis of modeled calculated density of states of chemically inhomogeneous FeTe1 x Sex structures further confirms that the two types of chalcogens, i.e., Te and Se, can be identified by their electronic signaturemore » and differentiated by their local chemical environment. This approach allows detailed chemical discrimination of the scanning tunneling microscopy data including separation of atomic identities, proximity, and local configuration effects and can be universally applicable to chemically and electronically inhomogeneous surfaces.« less

  11. Spatially resolved measurement of singlet delta oxygen by radar resonance-enhanced multiphoton ionization.

    PubMed

    Wu, Yue; Zhang, Zhili; Ombrello, Timothy M

    2013-07-01

    Coherent microwave Rayleigh scattering (Radar) from resonance-enhanced multiphoton ionization (REMPI) was demonstrated to directly and nonintrusively measure singlet delta oxygen, O(2)(a(1)Δ(g)), with high spatial resolution. Two different approaches, photodissociation of ozone and microwave discharge plasma in an argon and oxygen flow, were utilized for O(2)(a(1)Δ(g)) generation. The d(1)Π(g)←a(1)Δ(g) (3-0) and d(1)Π(g)←a(1)Δ(g) (1-0) bands of O(2)(a(1)Δ(g)) were detected by Radar REMPI for two different flow conditions. Quantitative absorption measurements using sensitive off-axis integrated cavity output spectroscopy (ICOS) was used simultaneously to evaluate the accuracy and sensitivity of the Radar REMPI technique. The detection limit of Radar REMPI was found to be comparable to the ICOS technique with a detection threshold of approximately 10(14) molecules/cm(3) but with a spatial resolution that was 8 orders of magnitude smaller than the ICOS technique. PMID:23811904

  12. Raman line imaging for spatially and temporally resolved mole fraction measurements in internal combustion engines.

    PubMed

    Miles, P C

    1999-03-20

    An optical diagnostic system based on line imaging of Raman-scattered light has been developed to study the mixing processes in internal combustion engines. The system permits multipoint, single laser-shot measurements of CO(2), O(2), N(2), C(3)H(8), and H(2)O mole fractions with submillimeter spatial resolution. Selection of appropriate system hardware is discussed, as are subsequent data reduction and analysis procedures. Results are reported for data obtained at multiple crank angles and in two different engine flow fields. Measurements are made at 12 locations simultaneously, each location having measurement volume dimensions of 0.5 mm x 0.5 mm x 0.9 mm. The data are analyzed to obtain statistics of species mole fractions: mean, rms, histograms, and both spatial and cross-species covariance functions. The covariance functions are used to quantify the accuracy of the measured rms mole fraction fluctuations, to determine the integral length scales of the mixture inhomogeneities, and to quantify the cycle-to-cycle fluctuations in bulk mixture composition under well-mixed conditions. PMID:18305796

  13. Spatially resolved localized vibrational mode spectroscopy of carbon in liquid encapsulated Czochralski grown gallium arsenide wafers

    SciTech Connect

    Yau, Waifan.

    1988-04-01

    Substitutional carbon on an arsenic lattice site is the shallowest and one of the most dominant acceptors in semi-insulating Liquid Encapsulated Czochralski (LEC) GaAs. However, the role of this acceptor in determining the well known W'' shape spatial variation of neutral EL2 concentration along the diameter of a LEC wafer is not known. In this thesis, we attempt to clarify the issue of the carbon acceptor's effect on this W'' shaped variation by measuring spatial profiles of this acceptor along the radius of three different as-grown LEC GaAs wafers. With localized vibrational mode absorption spectroscopy, we find that the profile of the carbon acceptor is relatively constant along the radius of each wafer. Average values of concentration are 8 {times} 10E15 cm{sup -3}, 1.1 {times} 10E15 cm{sup -3}, and 2.2 {times} 10E15 cm{sup -3}, respectively. In addition, these carbon acceptor LVM measurements indicate that a residual donor with concentration comparable to carbon exists in these wafers and it is a good candidate for the observed neutral EL2 concentration variation. 22 refs., 39 figs.

  14. Spatially resolving the very high energy emission from MGRO J2019+37 with VERITAS

    SciTech Connect

    Aliu, E.; Errando, M.; Aune, T.; Behera, B.; Chen, X.; Federici, S.; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Benbow, W.; Cerruti, M.; Berger, K.; Bird, R.; Bouvier, A.; Ciupik, L.; Connolly, M. P.; Cui, W.; Dumm, J.; Dwarkadas, V. V.; Falcone, A. E-mail: nahee@uchicago.edu; and others

    2014-06-10

    We present very high energy (VHE) imaging of MGRO J2019+37 obtained with the VERITAS observatory. The bright extended (∼2°) unidentified Milagro source is located toward the rich star formation region Cygnus-X. MGRO J2019+37 is resolved into two VERITAS sources. The faint, point-like source VER J2016+371 overlaps CTB 87, a filled-center remnant (SNR) with no evidence of a supernova remnant shell at the present time. Its spectrum is well fit in the 0.65-10 TeV energy range by a power-law model with photon index 2.3 ± 0.4. VER J2019+378 is a bright extended (∼1°) source that likely accounts for the bulk of the Milagro emission and is notably coincident with PSR J2021+3651 and the star formation region Sh 2–104. Its spectrum in the range 1-30 TeV is well fit with a power-law model of photon index 1.75 ± 0.3, among the hardest values measured in the VHE band, comparable to that observed near Vela-X. We explore the unusual spectrum and morphology in the radio and X-ray bands to constrain possible emission mechanisms for this source.

  15. Giant spatially-resolved self-assembled donor-acceptor molecular heterojunctions

    NASA Astrophysics Data System (ADS)

    Guest, Jeffrey R.; Smerdon, Joseph A.; Giebink, Noel C.; Guisinger, Nathan P.; Darancet, Pierre

    Despite theoretical models predicting that rectification ratios (RR) >1000 should be achievable in molecular rectifiers, demonstrations of this have been rare. It has also been extremely challenging to unravel the structure-function relationships on the nanometer length scales that determine their behavior. Using scanning tunneling microscopy (STM) and spectroscopy (STS), we show that RRs >1000 at biases <500 mV are realized in the two-molecule limit for self-assembled donor-acceptor bilayers of pentacene on C60 on Cu. We show that the system behaves as a molecular analog to a Schottky diode due to strong electronic coupling of C60 to the metallic substrate, and electronic transport is dominated by sequential tunneling from semiconducting pentacene to metallic C60. Furthermore, we demonstrate the extreme sensitivity of the low-bias I (V) characteristics to the molecularly-resolved structure of the heterojunction (HJ), which leads to negative differential resistance and ~ 100 × variation in the rectification ratio within 2 nm of the edge of the molecular HJ. Support was provided by the Department of Energy Office of Basic Energy Sciences (SISGR Grant DE-FG02-09ER16109).

  16. Energy release in the solar corona from spatially resolved magnetic braids.

    PubMed

    Cirtain, J W; Golub, L; Winebarger, A R; De Pontieu, B; Kobayashi, K; Moore, R L; Walsh, R W; Korreck, K E; Weber, M; McCauley, P; Title, A; Kuzin, S; DeForest, C E

    2013-01-24

    It is now apparent that there are at least two heating mechanisms in the Sun's outer atmosphere, or corona. Wave heating may be the prevalent mechanism in quiet solar periods and may contribute to heating the corona to 1,500,000 K (refs 1-3). The active corona needs additional heating to reach 2,000,000-4,000,000 K; this heat has been theoretically proposed to come from the reconnection and unravelling of magnetic 'braids'. Evidence favouring that process has been inferred, but has not been generally accepted because observations are sparse and, in general, the braided magnetic strands that are thought to have an angular width of about 0.2 arc seconds have not been resolved. Fine-scale braiding has been seen in the chromosphere but not, until now, in the corona. Here we report observations, at a resolution of 0.2 arc seconds, of magnetic braids in a coronal active region that are reconnecting, relaxing and dissipating sufficient energy to heat the structures to about 4,000,000 K. Although our 5-minute observations cannot unambiguously identify the field reconnection and subsequent relaxation as the dominant heating mechanism throughout active regions, the energy available from the observed field relaxation in our example is ample for the observed heating. PMID:23344359

  17. Thermomechanical Response of a Gas to Spatially Resolved Power Deposition Transients

    NASA Astrophysics Data System (ADS)

    Kassoy, David R.

    2015-11-01

    Liquid propellant rocket engine (LPRE) instability is characterized by growing pressure oscillations that affect the integrity and performance of the system. Modeling and prediction have been topics of intense interest to designers for more than 60 years. LPRE combustion provides a wonderful opportunity to employ thermomechanical concepts and mathematical methodologies to quantify the response of combustion chamber gases to spatially distributed, transient thermal energy deposition. Nondimensional Euler equations, including a power deposition term in the energy equation are used to identify crucial parameters, time and length scales, as well as levels of energy deposition, relevant to LPRE performance. The objective is to provide first principles explanations of physical phenomena responsible for mechanical disturbances observed in operating LPRE's.

  18. Spatially and temporally resolved gas distributions around heterogeneous catalysts using infrared planar laser-induced fluorescence

    PubMed Central

    Zetterberg, Johan; Blomberg, Sara; Gustafson, Johan; Evertsson, Jonas; Zhou, Jianfeng; Adams, Emma C.; Carlsson, Per-Anders; Aldén, Marcus; Lundgren, Edvin

    2015-01-01

    Visualizing and measuring the gas distribution in close proximity to a working catalyst is crucial for understanding how the catalytic activity depends on the structure of the catalyst. However, existing methods are not able to fully determine the gas distribution during a catalytic process. Here we report on how the distribution of a gas during a catalytic reaction can be imaged in situ with high spatial (400 μm) and temporal (15 μs) resolution using infrared planar laser-induced fluorescence. The technique is demonstrated by monitoring, in real-time, the distribution of carbon dioxide during catalytic oxidation of carbon monoxide above powder catalysts. Furthermore, we demonstrate the versatility and potential of the technique in catalysis research by providing a proof-of-principle demonstration of how the activity of several catalysts can be measured simultaneously, either in the same reactor chamber, or in parallel, in different reactor tubes. PMID:25953006

  19. Spatially resolved spectroscopy of AG Carinae, and direct evidence for stellar evolution: The central star of NGC 2392

    NASA Technical Reports Server (NTRS)

    Altner, Bruce; Shore, Steven N.

    1993-01-01

    We have performed spatially-resolved low dispersion long-slit spectroscopy for the circumstellar shell of the luminous blue variable AG Carinae with IUE between lambda lambda 1200 - 3200 A. At all positions a strong dust-scattered stellar continuum is detected. Only a few emission lines, FE II 2600 and O I (?) 1304, have been detected; the emission is stronger on the southern side of the shell. The UV surface brightness and derived dust properties are completely consistent with the groundbased and KAO FIR observations: the grains are large (0.1 - 1 micron), warm (45 - 100 K depending on composition), highly reflecting (C(sub sca)/C(sub abs) approximately equal to 1), and tie up about 10(exp -4) to 10(exp -3) solar mass of material. We also observe similarities of the results for HR Car and LBV's to those reported here.

  20. Spatially resolved penetration depth measurements and vortex manipulation in the ferromagnetic superconductor ErNi2B2C

    DOE PAGESBeta

    Wulferding, Dirk; Yang, Ilkyu; Yang, Jinho; Lee, Minkyung; Choi, Hee Cheul; Bud'ko, Sergey L.; Canfield, Paul C.; Yeom, Han Woong; Kim, Jeehoon

    2015-07-31

    We present a local probe study of the magnetic superconductor ErNi2B2C, using magnetic force microscopy at sub-Kelvin temperatures. ErNi2B2C is an ideal system to explore the effects of concomitant superconductivity and ferromagnetism. At 500 mK, far below the transition to a weakly ferromagnetic state, we directly observe a structured magnetic background on the micrometer scale. We determine spatially resolved absolute values of the magnetic penetration depth λ and study its temperature dependence as the system undergoes magnetic phase transitions from paramagnetic to antiferromagnetic, and to weak ferromagnetic, all within the superconducting regime. We estimate the absolute pinning force of Abrikosovmore » vortices, which shows a position dependence and temperature dependence as well, and discuss the possibility of the purported spontaneous vortex formation.« less

  1. Spatially resolved high-resolution x-ray spectroscopy of high-current plasma-focus discharges

    SciTech Connect

    ZajaPc, S.; Rzadkiewicz, J.; Scholz, M.; Paduch, M.; Zielinska, E.; Rosmej, O.; Yongtao, Zhao; Gojska, A.

    2010-10-15

    Soft x-ray emission from a Mather-type plasma-focus device (PF-1000) operated at {approx}400 kJ was measured. The high density and temperature plasma were generated by the discharge in the deuterium-argon gas mixture in the modified (high-current) plasma-focus configuration. A spherically bent mica crystal spectrograph viewing the axial output of the pinch region was used to measure the x-ray spectra. Spatially resolved spectra including the characteristic x-ray lines of highly ionized Ar and continua were recorded by means of an x-ray film. The x-ray emission of PF-1000 device was studied at different areas of the pinch.

  2. High Temporal and Spatial Resolution 3D Time-Resolved Contrast-Enhanced MR Angiography of the Hands and Feet

    PubMed Central

    Haider, Clifton R.; Riederer, Stephen J.; Borisch, Eric A.; Glockner, James F.; Grimm, Roger C.; Hulshizer, Thomas C.; Macedo, Thanila A.; Mostardi, Petrice M.; Rossman, Phillip J.; Vrtiska, Terri J.; Young, Phillip M.

    2010-01-01

    Methods are described for generating 3D time-resolved contrast-enhanced MR angiograms of the hands and feet. Given targeted spatial resolution and frame times, it is shown that acceleration of about one order of magnitude or more is necessary. This is obtained by a combination of 2D Sensitivity Encoding (SENSE) and homodyne (HD) acceleration methods. Image update times from 3.4 to 6.8 sec are provided in conjunction with view sharing. Modular receiver coil arrays are described which can be designed to the targeted vascular region. Images representative of the technique are generated in the vasculature of the hands and feet in volunteers and in patient studies. PMID:21698702

  3. Spatially resolved dielectric constant of confined water and its connection to the non-local nature of bulk water.

    PubMed

    Schaaf, Christian; Gekle, Stephan

    2016-08-28

    We use molecular dynamics simulations to compute the spatially resolved static dielectric constant of water in cylindrical and spherical nanopores as occurring, e.g., in protein water pockets or carbon nanotubes. For this, we derive a linear-response formalism which correctly takes into account the dielectric boundary conditions in the considered geometries. We find that in cylindrical confinement, the axial component behaves similar as the local density akin to what is known near planar interfaces. The radial dielectric constant shows some oscillatory features when approaching the surface if their radius is larger than about 2 nm. Most importantly, however, the radial component exhibits pronounced oscillations at the center of the cavity. These surprising features are traced back quantitatively to the non-local dielectric nature of bulk water. PMID:27586940

  4. Time- and spatial-resolved XAFS spectroscopy in a single shot: new analytical possibilities for in situ material characterization.

    PubMed

    Buzanich, Ana Guilherme; Radtke, Martin; Reinholz, Uwe; Riesemeier, Heinrich; Emmerling, Franziska

    2016-05-01

    A new concept that comprises both time- and lateral-resolved X-ray absorption fine-structure information simultaneously in a single shot is presented. This uncomplicated set-up was tested at the BAMline at BESSY-II (Berlin, Germany). The primary broadband beam was generated by a double multilayer monochromator. The transmitted beam through the sample is diffracted by a convexly bent Si (111) crystal, producing a divergent beam. This, in turn, is collected by either an energy-sensitive area detector, the so-called color X-ray camera, or by an area-sensitive detector based on a CCD camera, in θ-2θ geometry. The first tests were performed with thin metal foils and some iron oxide mixtures. A time resolution of lower than 1 s together with a spatial resolution in one dimension of at least 50 µm is achieved. PMID:27140157

  5. SPATIALLY RESOLVED GAS KINEMATICS WITHIN A Lyα NEBULA: EVIDENCE FOR LARGE-SCALE ROTATION

    SciTech Connect

    Prescott, Moire K. M.; Martin, Crystal L.; Dey, Arjun

    2015-01-20

    We use spatially extended measurements of Lyα as well as less optically thick emission lines from an ≈80 kpc Lyα nebula at z ≈ 1.67 to assess the role of resonant scattering and to disentangle kinematic signatures from Lyα radiative transfer effects. We find that the Lyα, C IV, He II, and C III] emission lines all tell a similar story in this system, and that the kinematics are broadly consistent with large-scale rotation. First, the observed surface brightness profiles are similar in extent in all four lines, strongly favoring a picture in which the Lyα photons are produced in situ instead of being resonantly scattered from a central source. Second, we see low kinematic offsets between Lyα and the less optically thick He II line (∼100-200 km s{sup –1}), providing further support for the argument that the Lyα and other emission lines are all being produced within the spatially extended gas. Finally, the full velocity field of the system shows coherent velocity shear in all emission lines: ≈500 km s{sup –1} over the central ≈50 kpc of the nebula. The kinematic profiles are broadly consistent with large-scale rotation in a gas disk that is at least partially stable against collapse. These observations suggest that the Lyα nebula represents accreting material that is illuminated by an offset, hidden active galactic nucleus or distributed star formation, and that is undergoing rotation in a clumpy and turbulent gas disk. With an implied mass of M(

  6. Spatially resolved observations of a coronal type II radio burst with multiple lanes

    NASA Astrophysics Data System (ADS)

    Zimovets, I. V.; Sadykov, V. M.

    2015-12-01

    Relative dynamics of the radio sources of the metric type II burst with three emission lanes and coronal mass ejection (CME) occurred in the lower corona (r≲ 1.5R⊙) during the SOL2011-02-16T14:19 event is studied. The observational data of the Nancay Radioheliograph (NRH) and the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) are used. These observations are also supplemented by the data sets obtained with the STEREO-A and -B, RHESSI, and GOES spacecraft, as well as with the ground-based solar radio spectrometers. It is found that the sources of the radio burst were located ahead of the expanding CME and had a complex spatial structure. The first and the second lanes were both emitted from the "magnetic funnel" - a bundle of open magnetic field lines separated the south and north systems of magnetic loops of the active region. Due to the projection effect and limited angular resolution of the NRH it is not possible to determine, whether the spatial locations of the radio sources of the two first emission lanes differed or not. It is argued that the observations support the hypothesis that the radio sources of the first and second lanes could be emitted respectively ahead of and behind a front of the same weak (the Alfvén Mach number MA ≈ 1.1-1.2), fast mode, quasi-parallel piston MHD shock wave. However, the third lane of the burst was definitely emitted from a different place. Its radio sources were situated ahead of the north-west part of the CME propagated through the north system of magnetic loops. This indicates clearly that different emission lanes of the same type II burst can be a result of propagation of different parts of a single CME through regions with different physical conditions (geometries and plasma densities) in the lower corona.

  7. Spatially Resolved Measurements of SO Emission on Io, while Eclipsed by Jupiter

    NASA Astrophysics Data System (ADS)

    de Pater, Imke; Laver, C.; Marchis, F.; Roe, H.; Macintosh, B.

    2006-09-01

    We observed Io during an eclipse on 12 November 2002 (UT) with the 10-m W.M. Keck II telescope, equipped with NIRSPEC and adaptive optics. We imaged the satellite in broadband Kp (2.2 micron) and H (1.65 micron), and in narrow bands centered at 1.58 and 1.70 micron, with a spatial resolution close to 0.05" (185 km on Io). These images revealed the eruption of a volcano close to Loki, possibly near Carancho like the eruption in 1998 (Macintosh et al. 2003). This doubled Io's flux as compared to the relatively quiescent state in Dec. 2001 (de Pater et al. 2004). In the 1.70 micron image a source shows up near Io's south pole, which is not seen in any of the other 3 images. We took spectra of Io in the 1.6-1.8 micron range, to map out the SO emission band at 1.708 micron, detected during a conventional "Io-in-eclipse" observation in September 1999 (de Pater et al 2002). While taking spectra, Io drifted through the spectral slit. We typically recorded 4 spectra during a drift episode, which enabled us to get some crude spatial resolution. Unfortunately, the SO emission was quite weak during this time, with a total photon flux 3-4 times lower than in 1999. This forced us to average spectra over large portions of Io's disk. From these spectra it is clear that Loki produces the bulk of the emission, even though it was not very active at the time, as deduced from its K-band flux. Not much SO emission is produced by the bright eruption, nor from Io's northern hemisphere. SO was detected from the southern hemisphere, and most likely is produced by the volcanic source that was detected near the south pole in the narrow 1.7 micron band filter. Supported by NSF grant AST-0406275 and CfAO.

  8. The Spatially-resolved Interacting Winds of Eta Carinae: Implications on the Orbit Orientation

    NASA Technical Reports Server (NTRS)

    Gull, Theodore R.; Nielsen, K.E.; Corcoran, M.; Hamaguchi, K.; Madura, T.; Russell, C.; Hillier, D.J.; Owocki. S.; Okazaki, A.T.

    2010-01-01

    Medium-dispersion long slit spectra, recorded by HST/STIS (R=8000, Theta=0.l"), resolve the extended wind-wind interaction region of the massive binary, Eta Carinae. During the high state, extending for about five years of the 5.54-year binary period, lines of [N II], [Fe III], [S III], [Ar III] and [Ne III] extend outwards to 0.4" with a velocity range of -500 to +200 km/s. By comparison, lines of [Fe II] and [Ni II] extend to 0.7" with a velocity range of -500 to +500 km/s. During the high state, driven by the lesser wind of Eta Car B and photo-ionized by the FUV of Eta Car B, the high excitation lines originate in or near the outer ballistic portions of the wind-wind interaction region. The lower excitation lines ([Fe II] and [Ni II D originate from the boundary regions of the dominating wind of Eta Car A. As the binary system has an eccentricity exceeding 0.9, the two stars approach quite close across the periastron, estimated to be within 1 to 2 AU. As a result, Eta Car B moves into the primary wind structure, cutting off the FUV supporting the ionization of the high state lines. Forbidden emission lines of the doubly-ionized species disappear, He II 4686 drops along with the collapse of the X-ray flux. This behavior is understood through the 3-D models of A. Okazaki and of E. R. Parkin and Pittard. Discussion will address the orbit orientation relative to the geometry of the Homunculus, ejected by Eta Carinae in the 1840s.

  9. Stirring in massive, young debris discs from spatially resolved Herschel images

    NASA Astrophysics Data System (ADS)

    Moór, A.; Kóspál, Á.; Ábrahám, P.; Apai, D.; Balog, Z.; Grady, C.; Henning, Th.; Juhász, A.; Kiss, Cs.; Krivov, A. V.; Pawellek, N.; Szabó, Gy. M.

    2015-02-01

    A significant fraction of main-sequence stars are encircled by dusty debris discs, where the short-lived dust particles are replenished through collisions between planetesimals. Most destructive collisions occur when the orbits of smaller bodies are dynamically stirred up, either by the gravitational effect of locally formed Pluto-sized planetesimals (self-stirring scenario), or via secular perturbation caused by an inner giant planet (planetary stirring). The relative importance of these scenarios in debris systems is unknown. Here, we present new Herschel Space Observatory imagery of 11 discs selected from the most massive and extended known debris systems. All discs were found to be extended at far-infrared wavelengths, five of them being resolved for the first time. We evaluated the feasibility of the self-stirring scenario by comparing the measured disc sizes with the predictions of the model calculated for the ages of our targets. We concluded that the self-stirring explanation works for seven discs. However, in four cases, the predicted pace of outward propagation of the stirring front, assuming reasonable initial disc masses, was far too low to explain the radial extent of the cold dust. Therefore, for HD 9672, HD 16743, HD 21997, and HD 95086, another explanation is needed. We performed a similar analysis for β Pic and HR 8799, reaching the same conclusion. We argue that planetary stirring is a promising possibility to explain the disc properties in these systems. In HR 8799 and HD 95086, we may already know the potential perturber, since their known outer giant planets could be responsible for the stirring process. Interestingly, the discs around HD 9672, HD 21997, and β Pic are also unique in harbouring detectable amount of molecular CO gas. Our study demonstrates that among the largest and most massive debris discs self-stirring may not be the only active scenario, and potentially planetary stirring is responsible for destructive collisions and debris

  10. The Spatially-resolved Interacting Winds of Eta Carinae: Implications on the Orbit Orientation

    NASA Astrophysics Data System (ADS)

    Gull, Theodore R.; Nielsen, K. E.; Corcoran, M.; Hamaguchi, K.; Madura, T.; Russell, C.; Hillier, D. J.; Owocki, S.; Okazaki, A. T.

    2010-01-01

    Medium-dispersion long slit spectra, recorded by HST/STIS (R=8000, Theta=0.1"), resolve the extended wind-wind interaction region of the massive binary, Eta Carinae. During the high state, extending for about five years of the 5.54-year binary period, lines of [N II], [Fe III], [S III], [Ar III] and [Ne III] extend outwards to 0.4" with a velocity range of -500 to +200 km/s. By comparison, lines of [Fe II] and [Ni II] extend to 0.7" with a velocity range of -500 to +500 km/s. During the high state, driven by the lesser wind of Eta Car B and photo-ionized by the FUV of Eta Car B, the high excitation lines originate in or near the outer ballistic portions of the wind-wind interaction region. The lower excitation lines ([Fe II] and [Ni II]) originate from the boundary regions of the dominating wind of Eta Car A. As the binary system has an eccentricity exceeding 0.9, the two stars approach quite close across the periastron, estimated to be within 1 to 2 AU. As a result, Eta Car B moves into the primary wind structure, cutting off the FUV supporting the ionization of the high state lines. Forbidden emission lines of the doubly-ionized species disappear, He II 4686 drops along with the collapse of the X-ray flux. This behavior is understood through the 3-D models of A. Okazaki and of E. R. Parkin and Pittard. Discussion will address the orbit orientation relative to the geometry of the Homunculus, ejected by Eta Carinae in the 1840s.

  11. Virgo cluster and field dwarf ellipticals in 3D - III. Spatially and temporally resolved stellar populations

    NASA Astrophysics Data System (ADS)

    Ryś, Agnieszka; Koleva, Mina; Falcón-Barroso, Jesús; Vazdekis, Alexandre; Lisker, Thorsten; Peletier, Reynier; van de Ven, Glenn

    2015-09-01

    We present the stellar population analysis of a sample of 12 dwarf elliptical galaxies, observed with the SAURON integral field unit, using the full-spectrum fitting method. We show that star formation histories (SFHs) resolved into two populations can be recovered even within a limited wavelength range, provided that high signal-to-noise ratio (S/N) data are used. We confirm that dEs have had complex SFHs, with star formation extending to (more) recent epochs: for the majority of our galaxies star formation activity was either still strong a few (≲5) Gyr ago or they experienced a secondary burst of star formation roughly at that time. This latter possibility is in agreement with the proposed dE formation scenario where tidal harassment drives the gas remaining in their progenitors inwards and induces a star formation episode. For one of our field galaxies, ID 0918, we find a correlation between its stellar population and kinematic properties, pointing to a possible merger origin of its kinematically decoupled core. One of our cluster objects, VCC 1431, appears to be composed exclusively of an old population (≳10-12 Gyr). Combining this with our earlier dynamical results, we conclude that the galaxy was either ram-pressure stripped early on in its evolution in a group environment and subsequently tidally heated, or that it evolved in situ in the cluster's central parts, compact enough to avoid tidal disruption. These are only two of the examples illustrating the SFH richness of these objects confirmed with our data.

  12. SPATIALLY RESOLVED HCN J = 4-3 AND CS J = 7-6 EMISSION FROM THE DISK AROUND HD 142527

    SciTech Connect

    Van der Plas, G.; Casassus, S.; Perez, S.; Christiaens, V.; Ménard, F.; Thi, W. F.; Pinte, C.

    2014-09-10

    The disk around HD 142527 attracts a great amount of attention compared to others because of its resolved (sub-)millimeter dust continuum that is concentrated into the shape of a horseshoe toward the north of the star. In this Letter we present spatially resolved ALMA detections of the HCN J = 4-3 and CS J = 7-6 emission lines. These lines give us a deeper view into the disk compared to the (optically thicker) CO isotopes. This is the first detection of CS J = 7-6 coming from a protoplanetary disk. Both emission lines are azimuthally asymmetric and are suppressed under the horseshoe-shaped continuum emission peak. A possible mechanism for explaining the decrease under the horseshoe-shaped continuum is the increased opacity coming from the higher dust concentration at the continuum peak. Lower dust and/or gas temperatures and an optically thick radio-continuum reduce line emission by freezing out and shielding emission from the far side of the disk.

  13. Fast spatially resolved exhaust gas recirculation (EGR) distribution measurements in an internal combustion engine using absorption spectroscopy.

    PubMed

    Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E; Perfetto, Anthony; Geckler, Sam; Partridge, William P

    2015-09-01

    Exhaust gas recirculation (EGR) in internal combustion engines is an effective method of reducing NOx emissions while improving efficiency. However, insufficient mixing between fresh air and exhaust gas can lead to cycle-to-cycle and cylinder-to-cylinder non-uniform charge gas mixtures of a multi-cylinder engine, which can in turn reduce engine performance and efficiency. A sensor packaged into a compact probe was designed, built and applied to measure spatiotemporal EGR distributions in the intake manifold of an operating engine. The probe promotes the development of more efficient and higher-performance engines by resolving high-speed in situ CO2 concentration at various locations in the intake manifold. The study employed mid-infrared light sources tuned to an absorption band of CO2 near 4.3 μm, an industry standard species for determining EGR fraction. The calibrated probe was used to map spatial EGR distributions in an intake manifold with high accuracy and monitor cycle-resolved cylinder-specific EGR fluctuations at a rate of up to 1 kHz. PMID:26253286

  14. Probing microscopic material properties inside simulated membranes through spatially resolved three-dimensional local pressure fields and surface tensions

    PubMed Central

    Kasson, Peter M.; Hess, Berk; Lindahl, Erik

    2013-01-01

    Cellular lipid membranes are spatially inhomogeneous soft materials. Materials properties such as pressure and surface tension thus show important microscopic-scale variation that is critical to many biological functions. We present a means to calculate pressure and surface tension in a 3D-resolved manner within molecular-dynamics simulations and show how such measurements can yield important insight. We also present the first corrections to local virial and pressure fields to account for the constraints typically used in lipid simulations that otherwise cause problems in highly oriented systems such as bilayers. Based on simulations of an asymmetric bacterial ion channel in a POPC bilayer, we demonstrate how 3D-resolved pressure can probe for both short-range and long-range effects from the protein on the membrane environment. We also show how surface tension is a sensitive metric for inter-leaflet equilibrium and can be used to detect even subtle imbalances between bilayer leaflets in a membrane-protein simulation. Since surface tension is known to modulate the function of many proteins, this effect is an important consideration for predictions of ion channel function. We outline a strategy by which our local pressure measurements, which we make available within a version of the GROMACS simulation package, may be used to design optimally equilibrated membrane-protein simulations. PMID:23318532

  15. Development of spatially resolved high resolution x-ray spectroscopy for fusion and light-source research

    NASA Astrophysics Data System (ADS)

    Lu, J.; Hill, K. W.; Bitter, M.; Delgado-Aparicio, L.; Pablant, N. A.; Efthimion, P.; Beiersdorfer, P.; Chen, H.; Widmann, K.; Sanchez del Rio, M.

    2014-09-01

    One dimensional spatially resolved high resolution x-ray spectroscopy with spherically bent crystals and 2D pixelated detectors is an established technique on magnetic confinement fusion (MCF) experiments world wide for Doppler measurements of spatial profiles of plasma ion temperature and flow velocity. This technique is being further developed for diagnosis of High Energy Density Physics (HEDP) plasmas at laser-plasma facilities and synchrotron/x-ray free electron laser (XFEL) facilities. Useful spatial resolution (micron scale) of such small-scale plasma sources requires magnification, because of the finite pixel size of x-ray CCD detectors (13.5 μm). A von-Hamos like spectrometer using spherical crystals is capable of magnification, as well as uniform sagittal focusing across the full x-ray spectrum, and is being tested in laboratory experiments using a tungsten-target microfocus (5-10 μm) x-ray tube and 13-μm pixel x-ray CCD. A spatial resolution better than 10 μm has been demonstrated. Good spectral resolution is indicated by small differences (0.02 - 0.1 eV) of measured line widths with best available published natural line widths. Progress and status of HEDP measurements and the physics basis for these diagnostics are presented. A new type of x-ray crystal spectrometer with a convex spherically bent crystal is also reported. The status of testing of a 2D imaging microscope using matched pairs of spherical crystals with x rays will also be presented. The use of computational x-ray optics codes in development of these instrumental concepts is addressed.

  16. An inverse method for determining the spatially resolved properties of viscoelastic–viscoplastic three-dimensional printed materials

    PubMed Central

    Chen, X.; Ashcroft, I. A.; Wildman, R. D.; Tuck, C. J.

    2015-01-01

    A method using experimental nanoindentation and inverse finite-element analysis (FEA) has been developed that enables the spatial variation of material constitutive properties to be accurately determined. The method was used to measure property variation in a three-dimensional printed (3DP) polymeric material. The accuracy of the method is dependent on the applicability of the constitutive model used in the inverse FEA, hence four potential material models: viscoelastic, viscoelastic–viscoplastic, nonlinear viscoelastic and nonlinear viscoelastic–viscoplastic were evaluated, with the latter enabling the best fit to experimental data. Significant changes in material properties were seen in the depth direction of the 3DP sample, which could be linked to the degree of cross-linking within the material, a feature inherent in a UV-cured layer-by-layer construction method. It is proposed that the method is a powerful tool in the analysis of manufacturing processes with potential spatial property variation that will also enable the accurate prediction of final manufactured part performance. PMID:26730216

  17. Spatially-resolved protein surface microsampling from tissue sections using liquid extraction surface analysis.

    PubMed

    Wisztorski, Maxence; Desmons, Annie; Quanico, Jusal; Fatou, Benoit; Gimeno, Jean-Pascal; Franck, Julien; Salzet, Michel; Fournier, Isabelle

    2016-06-01

    Tissue microenvironment characterization presents a challenge for a better understanding of the full complexity of a pathology. Unfortunately, making a precise "picture" of the disease needs an efficient microsampling method coupled to an accurate localization for performing region-dependent proteomics. Here, we present a method that enables rapid and reproducible extraction of proteins from a tissue section to analyze a specific region at a millimeter scale. The method used a liquid-microjunction extraction with conventional detergent solution for proteomics analysis. We successfully performed immunoblotting experiments and showed the possibility to retrieve and identify more than 1400 proteins from a 1-mm diameter spot size on tissue sections with a high degree of reproducibility both qualitatively and quantitatively. Moreover, the small size of the extracted region achieved by this sampling method allows the possibility to perform multiple extractions on different tissue section points. Ten points on a sagittal rat brain tissue section were analyzed and the measured proteins clearly distinguished the different parts of the brain, thus permitting precise functional mapping. We thus demonstrate that with this technology, it is possible to map the tissue microenvironment and gain an understanding of the molecular mechanisms at millimeter resolution. PMID:26929135

  18. Intense-field ionization of atoms and molecules: Spatially resolved ion detection and ultrashort optical vortices

    NASA Astrophysics Data System (ADS)

    Strohaber, James

    The interaction of light and matter has for many years provided a venue in which scientists have been able to increase their understanding of fundamental quantum mechanics and electromagnetism. The advent of the laser in the early sixties significantly changed the way in which experiments were performed. These coherent sources of radiation played a pivotal role in the investigations of new phenomenon such as multiphoton ionization. As time progressed many significant advances have been made in laser technology. For instance, the development of mode-locking techniques such as Q-switching and the nonlinear Kerr effect have made pulsed lasers possible (now down to ˜ 5 fs), the discovery of Chirped-Pulse-Amplification allowed for these ultrashort pulses to be amplified up to Joules in energy per pulse. As a result of these new advances in laser technology, new and exciting physics have been illuminated. When ultrashort intense laser fields interact with matter, one possible outcome is the ionization of the target into its constituents (atoms, molecules, electrons or photons). Because the constituents are usually ions which may have different masses and charges, time-of-flight (TOF) techniques are often employed in the analysis of the ionization yields. In these experiments, the usual quantity of physical interest is the ionization probability as a function of a well known intensity. However, in reality the impinging laser radiation possesses a distribution of intensities. To further add to this annoyance, it is difficult for a TOF spectrometer to distinguish between ions created at different intensities and the usual course of action is to integrate ions from over the entire focal volume. The inevitable result of this so-called spatial averaging is to limit information about the underlying physical process. Additionally, coherent sources of radiation have captured the attention of researchers whose main interests are in spatially modulating the phase and amplitude of

  19. The stellar populations of low-luminosity active galactic nuclei - III. Spatially resolved spectral properties

    NASA Astrophysics Data System (ADS)

    Cid Fernandes, R.; González Delgado, R. M.; Storchi-Bergmann, T.; Martins, L. Pires; Schmitt, H.

    2005-01-01

    In a recently completed survey of the stellar population properties of low-ionization nuclear emission-line regions (LINERs) and LINER/HII transition objects (TOs), we have identified a numerous class of galactic nuclei which stand out because of their conspicuous 108-9 yr populations, traced by high-order Balmer absorption lines and other stellar indices. These objects are called `young-TOs', because they all have TO-like emission-line ratios. In this paper we extend this previous work, which concentrated on the nuclear properties, by investigating the radial variations of spectral properties in low-luminosity active galactic nuclei (LLAGNs). Our analysis is based on high signal-to-noise ratio (S/N) long-slit spectra in the 3500-5500 Å interval for a sample of 47 galaxies. The data probe distances of typically up to 850 pc from the nucleus with a resolution of ~100 pc (~1 arcsec) and S/N ~ 30. Stellar population gradients are mapped by the radial profiles of absorption-line equivalent widths and continuum colours along the slit. These variations are further analysed by means of a decomposition of each spectrum in terms of template galaxies representative of very young (<=107 yr), intermediate age (108-9 yr) and old (1010 yr) stellar populations. This study reveals that young-TOs also differ from old-TOs and old-LINERs in terms of the spatial distributions of their stellar populations and dust. Specifically, our main findings are as follows. (i) Significant stellar population gradients are found almost exclusively in young-TOs. (ii) The intermediate age population of young-TOs, although heavily concentrated in the nucleus, reaches distances of up to a few hundred pc from the nucleus. Nevertheless, the half width at half-maximum of its brightness profile is more typically 100 pc or less. (iii) Objects with predominantly old stellar populations present spatially homogeneous spectra, be they LINERs or TOs. (iv) Young-TOs have much more dust in their central regions

  20. Spatially and Temporally Resolved Analysis of Environmental Trade-Offs in Electricity Generation.

    PubMed

    Peer, Rebecca A M; Garrison, Jared B; Timms, Craig P; Sanders, Kelly T

    2016-04-19

    The US power sector is a leading contributor of emissions that affect air quality and climate. It also requires a lot of water for cooling thermoelectric power plants. Although these impacts affect ecosystems and human health unevenly in space and time, there has been very little quantification of these environmental trade-offs on decision-relevant scales. This work quantifies hourly water consumption, emissions (i.e., carbon dioxide, nitrogen oxides, and sulfur oxides), and marginal heat rates for 252 electricity generating units (EGUs) in the Electric Reliability Council of Texas (ERCOT) region in 2011 using a unit commitment and dispatch model (UC&D). Annual, seasonal, and daily variations, as well as spatial variability are assessed. When normalized over the grid, hourly average emissions and water consumption intensities (i.e., output per MWh) are found to be highest when electricity demand is the lowest, as baseload EGUs tend to be the most water and emissions intensive. Results suggest that a large fraction of emissions and water consumption are caused by a small number of power plants, mainly baseload coal-fired generators. Replacing 8-10 existing power plants with modern natural gas combined cycle units would result in reductions of 19-29%, 51-55%, 60-62%, and 13-27% in CO2 emissions, NOx emissions, SOx emissions, and water consumption, respectively, across the ERCOT region for two different conversion scenarios. PMID:26967826

  1. Spatially Resolved Mapping of Electrical Conductivity around Individual Domain (Grain) Boundaries in Graphene

    SciTech Connect

    Li, An-Ping; Clark, Kendal W; Zhang, Xiaoguang; Vlassiouk, Ivan V; He, Guowei; Feenstra, Randall

    2013-01-01

    Graphene films can now be produced on the scale of up to meters. However, all large-scale graphene films contain topological defects that can significantly affect the characteristic transport behaviors of graphene. Here, we spatially map the structures and electronic transport near specific domain and grain boundaries in graphene, and evaluate effects of different types of defect on the electronic conductivity in epitaxial graphene grown on SiC and CVD graphene on Cu subsequently transferred to a SiO2 substrate. We use a combined approach with a multi-probe scanning tunneling potentiometry to investigate both structures and transport at individual grain boundaries and domain boundaries that are defined by coalesced grains, surface steps, and changes in layer thickness. It is found that the substrate step on SiC presents a significant potential barrier for electron transport of epitaxial graphene due to the reduced charge transport from the substrate at the step edges, monolayer-bilayer boundaries exhibit a high resistivity that can change depending on directions of the current across the boundary, and the resistivity of grain boundaries changes with the transition width of the disordered region between two adjacent grains in graphene. The detailed understanding of graphene defects will provide the feedback for controlled engineering of defects in large-scale graphene films.

  2. Spatially Resolved One-Dimensional Boundary States in Graphene-Hexagonal Boron Nitride Planar Heterostructures

    DOE PAGESBeta

    Li, An-Ping; Park, Jewook; Lee, Jaekwang; Liu, Lei; Baddorf, Arthur P.; Gu, Gong; Yoon, Mina; Park, Changwon; Durand, Corentin P.; Sumpter, Bobby G.

    2014-01-01

    Two-dimensional (2D) interfaces between crystalline materials have been shown to generate unusual interfacial electronic states in complex oxides1-4. Recently, a onedimensional (1D) polar-on-nonpolar interface has been realized in hexagonal boron nitride (hBN) and graphene heterostructures 5-10, where a coherent 1D boundary is expected to possess peculiar electronic states dictated by edge states of graphene and the polarity of hBN 11-13. Here we present a combined scanning tunneling microscopy (STM) and firstprinciples theory study of the graphene-hBN boundary to provide a rare glimpse into the spatial and energetic distributions of the 1D boundary states in real-space. The interfaces studied here aremore » crystallographically coherent with sharp transitions from graphene zigzag edges to B (or N) terminated hBN atomic layers on a Cu foil substrate5. The revealed boundary states are about 0.6 eV below or above the Fermi energy depending on the termination of the hBN at the boundary, and are extended along but localized at the boundary with a lateral thickness of 2-3nm. These results suggest that unconventional physical effects similar to those observed at 2D interfaces can also exist in lower dimensions, opening a route for tuning of electronic properties at interfaces in 2D heterostructures.« less

  3. THE SPATIALLY RESOLVED H{alpha}-EMITTING WIND STRUCTURE OF P CYGNI

    SciTech Connect

    Balan, Aurelian; Tycner, C.; Zavala, R. T.; Benson, J. A.; Hutter, D. J.; Templeton, M. E-mail: c.tycner@cmich.ed E-mail: jbenson@nofs.navy.mi E-mail: matthewt@aavso.or

    2010-06-15

    High spatial resolution observations of the H{alpha}-emitting wind structure associated with the luminous blue variable star P Cygni were obtained with the Navy Prototype Optical Interferometer. These observations represent the most comprehensive interferometric data set on P Cyg to date. We demonstrate how the apparent size of the H{alpha}-emitting region of the wind structure of P Cyg compares between the 2005, 2007, and 2008 observing seasons and how this relates to the H{alpha} line spectroscopy. Using the data sets from 2005, 2007, and 2008 observing seasons, we fit a circularly symmetric Gaussian model to the interferometric signature from the H{alpha}-emitting wind structure of P Cyg. Based on our results, we conclude that the radial extent of the H{alpha}-emitting wind structure around P Cyg is stable at the 10% level. We also show how the radial distribution of the H{alpha} flux from the wind structure deviates from a Gaussian shape, whereas a two-component Gaussian model is sufficient to fully describe the H{alpha}-emitting region around P Cyg.

  4. The Future of Spatially-Resolved Polychromatic Neutron and X-Ray Microdiffraction

    SciTech Connect

    Ice, Gene E.

    2009-09-25

    Polychromatic microdiffraction is an emerging materials-characterization tool made practical by powerful X-ray and neutron sources, and by advanced optics and software. With polychromatic techniques, local crystalline properties including phase, texture (orientation), elastic strain, and defect density can be mapped with submicron spatial resolution in three dimensions. Here, we describe the evolving ability to nondestructively map local crystal structure in three dimensions and discuss how future advances will help address long-standing issues of inhomogeneous grain growth, deformation, fracture, and elastic strain. Current and future applications impact virtually all materials including electronic, solar, and light-emitting-diode (LED) materials, nanomaterials, structural materials, and joining materials. In addition, the ability to focus small beams on small samples dramatically increases signal-to-noise and greatly reduces the cost for extreme environmental chambers required for high-pressure, high-temperature, high-magnetic field or corrosive environments. Polychromatic techniques efficiently use source brilliance and minimize the required sample volume, which is essential for hard-to-make materials, irreplaceable materials, and for radioactive, toxic, or otherwise dangerous materials. New polychromatic neutron capabilities will significantly extend the range of samples that can be studied with neutrons and presents important new scientific opportunities for studies of magnetic materials, low Z elements, fragile crystal structures, and small samples in extreme environments.

  5. Spatially resolved shock response at dry metallic multi-material interfaces

    NASA Astrophysics Data System (ADS)

    Collinson, Mark A.; Chapman, David J.; Eakins, Daniel E.

    2014-05-01

    The high strain-rate behaviour of multi-component systems is often dominated by mediation at material interfaces. The extent to which a materials microstructure influences dynamic friction and relative sliding response remains an area of active study. Initial results from a study on the behaviour of dry metallic interfaces under the passage of a controlled loading wave are presented. Held in close contact along a single planar interface, oblique shock waves were generated along the boundary by direct copper flyer impact at velocities in the range 250 ms-1 - 300 ms-1. Both the 100 mm and 13 mm bore gas guns located at Imperial College London were utilised for this purpose. A line-imaging velocity interferometer system for any reflector (VISAR) system was used to directly record the velocity profile across the contact interface, providing a measure of any spatially dependent response while photon doppler velocimetry (PDV) was used to determine the far field response. Comparisons of these results against current generation hydrocode models are presented, with significant deviations from the computationally predicted results identified in the peak shock state immediately following shock breakout.

  6. Spatially Resolved Photoexcited Charge-Carrier Dynamics in Phase-Engineered Monolayer MoS2

    DOE PAGESBeta

    Yamaguchi, Hisato; Blancon, Jean-Christophe; Kappera, Rajesh; Lei, Sidong; Najmaei, Sina; Mangum, Benjamin D.; Gupta, Gautam; Ajayan, Pulickel M.; Lou, Jun; Chhowalla, Manish; et al

    2014-12-18

    A fundamental understanding of the intrinsic optoelectronic properties of atomically thin transition metal dichalcogenides (TMDs) is crucial for its integration into high performance semiconductor devices. We investigate the transport properties of chemical vapor deposition (CVD) grown monolayer molybdenum disulfide (MoS2) under photo-excitation using correlated scanning photocurrent microscopy and photoluminescence imaging. We examined the effect of local phase transformation underneath the metal electrodes on the generation of photocurrent across the channel length with diffraction-limited spatial resolution. While maximum photocurrent generation occurs at the Schottky contacts of semiconducting (2H-phase) MoS2, after the metallic phase transformation (1T-phase), the photocurrent peak is observed towardsmore » the center of the device channel, suggesting a strong reduction of native Schottky barriers. Analysis using the bias and position dependence of the photocurrent indicates that the Schottky barrier heights are few meV for 1T- and ~200 meV for 2H-contacted devices. We also demonstrate that a reduction of native Schottky barriers in a 1T device enhances the photo responsivity by more than one order of magnitude, a crucial parameter in achieving high performance optoelectronic devices. The obtained results pave a pathway for the fundamental understanding of intrinsic optoelectronic properties of atomically thin TMDs where Ohmic contacts are necessary for achieving high efficiency devices with low power consumption.« less

  7. Spatially Resolved One-Dimensional Boundary States in Graphene-Hexagonal Boron Nitride Planar Heterostructures

    SciTech Connect

    Li, An-Ping; Park, Jewook; Lee, Jaekwang; Liu, Lei; Baddorf, Arthur P.; Gu, Gong; Yoon, Mina; Park, Changwon; Durand, Corentin P.; Sumpter, Bobby G.

    2014-01-01

    Two-dimensional (2D) interfaces between crystalline materials have been shown to generate unusual interfacial electronic states in complex oxides1-4. Recently, a onedimensional (1D) polar-on-nonpolar interface has been realized in hexagonal boron nitride (hBN) and graphene heterostructures 5-10, where a coherent 1D boundary is expected to possess peculiar electronic states dictated by edge states of graphene and the polarity of hBN 11-13. Here we present a combined scanning tunneling microscopy (STM) and firstprinciples theory study of the graphene-hBN boundary to provide a rare glimpse into the spatial and energetic distributions of the 1D boundary states in real-space. The interfaces studied here are crystallographically coherent with sharp transitions from graphene zigzag edges to B (or N) terminated hBN atomic layers on a Cu foil substrate5. The revealed boundary states are about 0.6 eV below or above the Fermi energy depending on the termination of the hBN at the boundary, and are extended along but localized at the boundary with a lateral thickness of 2-3nm. These results suggest that unconventional physical effects similar to those observed at 2D interfaces can also exist in lower dimensions, opening a route for tuning of electronic properties at interfaces in 2D heterostructures.

  8. Spatially-Resolved Analyses of Aerodynamic Fallout from a Uranium-Fueled Nuclear Test

    DOE PAGESBeta

    Lewis, L. A.; Knight, K. B.; Matzel, J. E.; Prussin, S. G.; Zimmer, M. M.; Kinman, W S; Ryerson, F. J.; Hutcheon, I. D.

    2015-07-28

    The fiive silicate fallout glass spherules produced in a uranium-fueled, near-surface nuclear test were characterized by secondary ion mass spectrometry, electron probe microanalysis, autoradiography, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Several samples display compositional heterogeneity suggestive of incomplete mixing between major elements and natural U (238U/235U = 0.00725) and enriched U. Samples exhibit extreme spatial heterogeneity in U isotopic composition with 0.02 < 235U/238U < 11.84 among all five spherules and 0.02 < 235U/238U < 7.41 within a single spherule. Moreover, in two spherules, the 235U/238U ratio is correlated with changes in major element composition, suggesting the agglomeration ofmore » chemically and isotopically distinct molten precursors. Two samples are nearly homogenous with respect to major element and uranium isotopic composition, suggesting extensive mixing possibly due to experiencing higher temperatures or residing longer in the fireball. Linear correlations between 234U/238U, 235U/238U, and 236U/238U ratios are consistent with a two-component mixing model, which is used to illustrate the extent of mixing between natural and enriched U end members.« less

  9. Spatially-Resolved Analyses of Aerodynamic Fallout from a Uranium-Fueled Nuclear Test

    SciTech Connect

    Lewis, L. A.; Knight, K. B.; Matzel, J. E.; Prussin, S. G.; Zimmer, M. M.; Kinman, W S; Ryerson, F. J.; Hutcheon, I. D.

    2015-07-28

    The fiive silicate fallout glass spherules produced in a uranium-fueled, near-surface nuclear test were characterized by secondary ion mass spectrometry, electron probe microanalysis, autoradiography, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Several samples display compositional heterogeneity suggestive of incomplete mixing between major elements and natural U (238U/235U = 0.00725) and enriched U. Samples exhibit extreme spatial heterogeneity in U isotopic composition with 0.02 < 235U/238U < 11.84 among all five spherules and 0.02 < 235U/238U < 7.41 within a single spherule. Moreover, in two spherules, the 235U/238U ratio is correlated with changes in major element composition, suggesting the agglomeration of chemically and isotopically distinct molten precursors. Two samples are nearly homogenous with respect to major element and uranium isotopic composition, suggesting extensive mixing possibly due to experiencing higher temperatures or residing longer in the fireball. Linear correlations between 234U/238U, 235U/238U, and 236U/238U ratios are consistent with a two-component mixing model, which is used to illustrate the extent of mixing between natural and enriched U end members.

  10. Spatially-resolved analyses of aerodynamic fallout from a uranium-fueled nuclear test.

    PubMed

    Lewis, L A; Knight, K B; Matzel, J E; Prussin, S G; Zimmer, M M; Kinman, W S; Ryerson, F J; Hutcheon, I D

    2015-10-01

    Five silicate fallout glass spherules produced in a uranium-fueled, near-surface nuclear test were characterized by secondary ion mass spectrometry, electron probe microanalysis, autoradiography, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Several samples display compositional heterogeneity suggestive of incomplete mixing between major elements and natural U ((238)U/(235)U = 0.00725) and enriched U. Samples exhibit extreme spatial heterogeneity in U isotopic composition with 0.02 < (235)U/(238)U < 11.84 among all five spherules and 0.02 < (235)U/(238)U < 7.41 within a single spherule. In two spherules, the (235)U/(238)U ratio is correlated with changes in major element composition, suggesting the agglomeration of chemically and isotopically distinct molten precursors. Two samples are nearly homogenous with respect to major element and uranium isotopic composition, suggesting extensive mixing possibly due to experiencing higher temperatures or residing longer in the fireball. Linear correlations between (234)U/(238)U, (235)U/(238)U, and (236)U/(238)U ratios are consistent with a two-component mixing model, which is used to illustrate the extent of mixing between natural and enriched U end members. PMID:26225462

  11. Spatially resolved analysis of variation in barley (Hordeum vulgare) grain micronutrient accumulation.

    PubMed

    Detterbeck, Amelie; Pongrac, Paula; Rensch, Stefan; Reuscher, Stefan; Pečovnik, Matic; Vavpetič, Primož; Pelicon, Primož; Holzheu, Stefan; Krämer, Ute; Clemens, Stephan

    2016-09-01

    Genetic biofortification requires knowledge on natural variation and the underlying mechanisms of micronutrient accumulation. We therefore studied diversity in grain micronutrient concentrations and spatial distribution in barley (Hordeum vulgare), a genetically tractable model cereal and an important crop with widespread cultivation. We assembled a diverse collection of barley cultivars and landraces and analysed grain micronutrient profiles in genebank material and after three independent cultivations. Lines with contrasting grain zinc (Zn) accumulation were selected for in-depth analysis of micronutrient distribution within the grain by micro-proton-induced X-ray emission (μ-PIXE). Also, we addressed association with grain cadmium (Cd) accumulation. The analysis of > 120 lines revealed substantial variation, especially in grain Zn concentrations. A large fraction of this variation is due to genetic differences. Grain dissection and μ-PIXE analysis of contrasting lines showed that differences in grain Zn accumulation apply to all parts of the grain including the endosperm. Cd concentrations exceeded the Codex Alimentarius threshold in most of the representative barley lines after cultivation in a Cd-contaminated agricultural soil. Two important conclusions for biofortification are: first, high-Zn grains contain more Zn also in the consumed parts of the grain; and second, higher micronutrient concentrations are strongly associated with higher Cd accumulation. PMID:27125321

  12. On-board monitoring of 2-D spatially-resolved temperatures in cylindrical lithium-ion batteries: Part I. Low-order thermal modelling

    NASA Astrophysics Data System (ADS)

    Richardson, Robert R.; Zhao, Shi; Howey, David A.

    2016-09-01

    Estimating the temperature distribution within Li-ion batteries during operation is critical for safety and control purposes. Although existing control-oriented thermal models - such as thermal equivalent circuits (TEC) - are computationally efficient, they only predict average temperatures, and are unable to predict the spatially resolved temperature distribution throughout the cell. We present a low-order 2D thermal model of a cylindrical battery based on a Chebyshev spectral-Galerkin (SG) method, capable of predicting the full temperature distribution with a similar efficiency to a TEC. The model accounts for transient heat generation, anisotropic heat conduction, and non-homogeneous convection boundary conditions. The accuracy of the model is validated through comparison with finite element simulations, which show that the 2-D temperature field (r, z) of a large format (64 mm diameter) cell can be accurately modelled with as few as 4 states. Furthermore, the performance of the model for a range of Biot numbers is investigated via frequency analysis. For larger cells or highly transient thermal dynamics, the model order can be increased for improved accuracy. The incorporation of this model in a state estimation scheme with experimental validation against thermocouple measurements is presented in the companion contribution (http://www.sciencedirect.com/science/article/pii/S0378775316308163)

  13. Spatially resolved genomic, stable isotopic, and lipid analyses of a modern freshwater microbialite from Cuatro Ciénegas, Mexico.

    PubMed

    Nitti, Anthony; Daniels, Camille A; Siefert, Janet; Souza, Valeria; Hollander, David; Breitbart, Mya

    2012-07-01

    Microbialites are biologically mediated carbonate deposits found in diverse environments worldwide. To explore the organisms and processes involved in microbialite formation, this study integrated genomic, lipid, and both organic and inorganic stable isotopic analyses to examine five discrete depth horizons spanning the surface 25 mm of a modern freshwater microbialite from Cuatro Ciénegas, Mexico. Distinct bacterial communities and geochemical signatures were observed in each microbialite layer. Photoautotrophic organisms accounted for approximately 65% of the sequences in the surface community and produced biomass with distinctive lipid biomarker and isotopic (δ(13)C) signatures. This photoautotrophic biomass was efficiently degraded in the deeper layers by heterotrophic organisms, primarily sulfate-reducing proteobacteria. Two spatially distinct zones of carbonate precipitation were observed within the microbialite, with the first zone corresponding to the phototroph-dominated portion of the microbialite and the second zone associated with the presence of sulfate-reducing heterotrophs. The coupling of photoautotrophic production, heterotrophic decomposition, and remineralization of organic matter led to the incorporation of a characteristic biogenic signature into the inorganic CaCO(3) matrix. Overall, spatially resolved multidisciplinary analyses of the microbialite enabled correlations to be made between the distribution of specific organisms, precipitation of carbonate, and preservation of unique lipid and isotopic geochemical signatures. These findings are critical for understanding the formation of modern microbialites and have implications for the interpretation of ancient microbialite records. PMID:22882001

  14. Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

    NASA Astrophysics Data System (ADS)

    Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; Strelcov, Evgheni; Kumar, Amit; Tselev, Alexander; Rahani, Ehasan Kabiri; Shenoy, Vivek B.; Yamamoto, Takahisa; Shibata, Naoya; Ikuhara, Yuichi; Kalinin, Sergei V.

    2014-10-01

    Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were further correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. These studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses.

  15. Visualisation of structural inhomogeneities in strongly scattering media using the method of spatially-resolved reflectometry: Monte Carlo simulation

    SciTech Connect

    Bykov, A V; Priezzhev, A V; Myllylae, Risto A

    2011-06-30

    Two-dimensional spatial intensity distributions of diffuse scattering of near-infrared laser radiation from a strongly scattering medium, whose optical properties are close to those of skin, are obtained using Monte Carlo simulation. The medium contains a cylindrical inhomogeneity with the optical properties, close to those of blood. It is shown that stronger absorption and scattering of light by blood compared to the surrounding medium leads to the fact that the intensity of radiation diffusely reflected from the surface of the medium under study and registered at its surface has a local minimum directly above the cylindrical inhomogeneity. This specific feature makes the method of spatially-resolved reflectometry potentially applicable for imaging blood vessels and determining their sizes. It is also shown that blurring of the vessel image increases almost linearly with increasing vessel embedment depth. This relation may be used to determine the depth of embedment provided that the optical properties of the scattering media are known. The optimal position of the sources and detectors of radiation, providing the best imaging of the vessel under study, is determined. (biophotonics)

  16. Spatially resolved, diffuse reflectance imaging for subsurface pattern visualization toward development of a lensless imaging platform: phantom experiments

    NASA Astrophysics Data System (ADS)

    Schelkanova, Irina; Pandya, Aditya; Saiko, Guennadi; Nacy, Lidia; Babar, Hannan; Shah, Duoaud; Lilge, Lothar; Douplik, Alexandre

    2016-01-01

    A portable, spatially resolved, diffuse reflectance lensless imaging technique based on the charge-coupled device or complementary metal-oxide semiconductor sensor directly coupled to the fiber optic bundle is proposed for visualization of subsurface structures such as superficial microvasculature in the epithelium. We discuss an experimental method for emulating a lensless imaging setup via raster scanning a single fiber-optic cable over a microfluidic phantom containing periodic hemoglobin absorption contrast. To evaluate the ability of the technique to recover information about the subsurface linear structures, scattering layers formed of the Sylgard® 184 Silicone Elastomer and titanium dioxide were placed atop the microfluidic phantom. Thickness of the layers ranged from 0.2 to 0.7 mm, and the values of the reduced scattering coefficient (μs‧) were between 0.85 and 4.25 mm-1. The results demonstrate that fiber-optic, lensless platform can be used for two-dimensional imaging of absorbing inclusions in diffuse reflectance mode. In these experiments, it was shown that diffuse reflectance imaging can provide sufficient spatial sampling of the phantom for differentiation of 30 μm structural features of the embedded absorbing pattern inside the scattering media.

  17. Fully automated spatially resolved reflectance spectrometer for the determination of the absorption and scattering in turbid media

    NASA Astrophysics Data System (ADS)

    Foschum, F.; Jäger, M.; Kienle, A.

    2011-10-01

    We describe a fully automated setup which is based on measurements of the spatially resolved reflectance for the determination of the reduced scattering and absorption coefficients in semi-infinite turbid media. The sample is illuminated with a xenon light source in combination with a monochromator enabling the scan of the wavelength from 450 nm to 950 nm. Reflected light from the sample is detected with a CCD camera providing a high spatial resolution. The essential steps for signal processing including, e.g., the consideration of the optical transfer function and the correct treatment of the background subtraction, are presented. The solutions of the diffusion theory and of the radiative transfer theory are investigated regarding the exact detection and illumination geometry. Systematic errors caused by using the different theories for fitting the optical parameters are characterized. The system was validated using liquid phantoms which contain Intralipid 20% and ink, and the measurement range of the system is specified. Further, we carefully characterized the optical properties of Intralipid 20% in the wavelength range between 450 nm and 950 nm.

  18. Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

    SciTech Connect

    Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; Strelcov, Evgheni; Kumar, Amit; Tselev, Alexander; Rahani, Ehasan Kabiri; Shenoy, Vivek B.; Yamamoto, Takahisa; Shibata, Naoya; Ikuhara, Yuichi; Kalinin, Sergei V.

    2014-10-22

    Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were further correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. In conclusion, these studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses.

  19. Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

    DOE PAGESBeta

    Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; Strelcov, Evgheni; Kumar, Amit; Tselev, Alexander; Rahani, Ehasan Kabiri; Shenoy, Vivek B.; Yamamoto, Takahisa; Shibata, Naoya; et al

    2014-10-22

    Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were furthermore » correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. In conclusion, these studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses.« less

  20. Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

    PubMed Central

    Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; Strelcov, Evgheni; Kumar, Amit; Tselev, Alexander; Rahani, Ehasan Kabiri; Shenoy, Vivek B.; Yamamoto, Takahisa; Shibata, Naoya; Ikuhara, Yuichi; Kalinin, Sergei V.

    2014-01-01

    Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were further correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. These studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses. PMID:25335689

  1. Integrated circuit-based electrochemical sensor for spatially resolved detection of redox-active metabolites in biofilms

    PubMed Central

    Bellin, Daniel L.; Sakhtah, Hassan; Rosenstein, Jacob K.; Levine, Peter M.; Thimot, Jordan; Emmett, Kevin; Dietrich, Lars E. P.; Shepard, Kenneth L.

    2014-01-01

    Despite advances in monitoring spatiotemporal expression patterns of genes and proteins with fluorescent probes, direct detection of metabolites and small molecules remains challenging. A technique for spatially resolved detection of small molecules would benefit the study of redox-active metabolites produced by microbial biofilms, which can drastically affect colony development. Here we present an integrated circuit-based electrochemical sensing platform featuring an array of working electrodes and parallel potentiostat channels. “Images” over a 3.25 × 0.9 mm area can be captured with a diffusion-limited spatial resolution of 750 μm. We demonstrate that square wave voltammetry can be used to detect, identify, and quantify (for concentrations as low as 2.6 μM) four distinct redox-active metabolites called phenazines. We characterize phenazine production in both wild-type and mutant Pseudomonas aeruginosa PA14 colony biofilms, and find correlations with fluorescent reporter imaging of phenazine biosynthetic gene expression. PMID:24510163

  2. Spatially resolved study of the physical properties of the ionized gas in NGC 595

    NASA Astrophysics Data System (ADS)

    Relaño, M.; Monreal-Ibero, A.; Vílchez, J. M.; Kennicutt, R. C.

    2010-03-01

    We present Integral Field Spectroscopy (IFS) of NGC 595, one of the most luminous HII regions in M33. This type of observations allows us to study the variation of the principal emission-line ratios across the surface of the nebula. At each position of the field of view, we fit the main emission-line features of the spectrum within the spectral range of 3650-6990Å and create maps of the principal emission-line ratios for the total surface of the region. The extinction map derived from the Balmer decrement and the absorbed Hα luminosity show good spatial correlation with the 24μm emission from Spitzer. We also show here the capability of the IFS to study the existence of Wolf-Rayet (WR) stars, identifying the previously catalogued WR stars and detecting a new candidate towards the north of the region. The ionization structure of the region nicely follows the Hα shell morphology and is clearly related to the location of the central ionizing stars. The electron density distribution does not show strong variations within the HII region nor any trend with the Hα emission distribution. We study the behaviour within the HII region of several classical emission-line ratios proposed as metallicity calibrators: while [NII]/Hα and [NII]/[OIII] show important variations, the R23 index is substantially constant across the surface of the nebula, despite the strong variation of the ionization parameter as a function of the radial distance from the ionizing stars. These results show the reliability in using the R23 index to characterize the metallicity of HII regions even when only a fraction of the total area is covered by the observations.

  3. Spatially resolved galactic wind in lensed galaxy RCSGA 032727-132609

    NASA Astrophysics Data System (ADS)

    Bordoloi, Rongmon; Rigby, Jane R.; Tumlinson, Jason; Bayliss, Matthew B.; Sharon, Keren; Gladders, Michael G.; Wuyts, Eva

    2016-05-01

    We probe the spatial distribution of outflowing gas along four lines of sight separated by up to 6 kpc in a gravitationally lensed star-forming galaxy at z = 1.70. Using Mg II and Fe II emission and absorption as tracers, we find that the clumps of star formation are driving galactic outflows with velocities of -170 to -250 km s-1. The velocities of Mg II emission are redshifted with respect to the systemic velocities of the galaxy, consistent with being back-scattered. By contrast, the Fe II fluorescent emission lines are either slightly blueshifted or at the systemic velocity of the galaxy. Taken together, the velocity structure of the Mg II and Fe II emission is consistent with arising through scattering in galactic winds. Assuming a thin shell geometry for the outflowing gas, the estimated masses carried out by these outflows are large (≳30-50 M⊙ yr- 1), with mass loading factors several times the star formation rate. Almost 20 per cent to 50 per cent of the blueshifted absorption probably escapes the gravitational potential of the galaxy. In this galaxy, the outflow is `locally sourced', that is, the properties of the outflow in each line of sight are dominated by the properties of the nearest clump of star formation; the wind is not global to the galaxy. The mass outflow rates and the momentum flux carried out by outflows in individual star-forming knots of this object are comparable to that of starburst galaxies in the local Universe.

  4. Evaluation of a spatially resolved forest fire smoke model for population-based epidemiologic exposure assessment.

    PubMed

    Yao, Jiayun; Eyamie, Jeff; Henderson, Sarah B

    2016-05-01

    Exposure to forest fire smoke (FFS) is associated with multiple adverse health effects, mostly respiratory. Findings for cardiovascular effects have been inconsistent, possibly related to the limitations of conventional methods to assess FFS exposure. In previous work, we developed an empirical model to estimate smoke-related fine particulate matter (PM2.5) for all populated areas in British Columbia (BC), Canada. Here, we evaluate the utility of our model by comparing epidemiologic associations between modeled and measured PM2.5. For each local health area (LHA), we used Poisson regression to estimate the effects of PM2.5 estimates and measurements on counts of medication dispensations and outpatient physician visits. We then used meta-regression to estimate the overall effects. A 10 μg/m(3) increase in modeled PM2.5 was associated with increased sabutamol dispensations (RR=1.04, 95% CI 1.03-1.06), and physician visits for asthma (1.06, 1.04-1.08), COPD (1.02, 1.00-1.03), lower respiratory infections (1.03, 1.00-1.05), and otitis media (1.05, 1.03-1.07), all comparable to measured PM2.5. Effects on cardiovascular outcomes were only significant using model estimates in all LHAs during extreme fire days. This suggests that the exposure model is a promising tool for increasing the power of epidemiologic studies to detect the health effects of FFS via improved spatial coverage and resolution. PMID:25294305

  5. SPATIALLY RESOLVED CHEMISTRY IN NEARBY GALAXIES. II. THE NUCLEAR BAR IN MAFFEI 2

    SciTech Connect

    Meier, David S.; Turner, Jean L. E-mail: turner@astro.ucla.edu

    2012-08-20

    We present 2''-10'' imaging of 11 transitions from 9 molecular species across the nuclear bar in Maffei 2. The data were obtained with the BIMA and OVRO interferometers. The 10 detected transitions are compared with existing CO isotopologues, HCN, CS, and millimeter continuum data. Dramatic spatial variations among the mapped species are observed across the nuclear bar. A principal component analysis is performed to characterize correlations between the transitions, star formation, and molecular column density. The analysis reveals that HCN, HNC, HCO{sup +}, and 3 mm continuum are tightly correlated, indicating a direct connection to massive star formation. We find two main morphologically distinct chemical groups, CH{sub 3}OH, SiO, and HNCO comprising the grain chemistry molecules, versus HCN, HNC, HCO{sup +}, and C{sub 2}H, molecules strong in the presence of star formation. The grain chemistry molecules, HNCO, CH{sub 3}OH, and SiO, trace hydrodynamical bar shocks. The near constancy of the HNCO/CH{sub 3}OH, SiO/CH{sub 3}OH, and SiO/HNCO ratios argues that shock properties are uniform across the nucleus. HCN/HCO{sup +}, HCN/HNC, HCN/CS, and HCN/CO ratios are explained primarily by variations in density. High HCO{sup +}/N{sub 2}H{sup +} ratios are correlated with the C{sub 2}H line, suggesting that this ratio may be a powerful new dense photon-dominated region probe in external galaxies. C{sub 2}H reveals a molecular outflow along the minor axis. The morphology and kinematics of the outflow are consistent with an outflow age of 6-7 Myr.

  6. Spatially resolved flux measurements of NOx from London suggest significantly higher emissions than predicted by inventories.

    PubMed

    Vaughan, Adam R; Lee, James D; Misztal, Pawel K; Metzger, Stefan; Shaw, Marvin D; Lewis, Alastair C; Purvis, Ruth M; Carslaw, David C; Goldstein, Allen H; Hewitt, C Nicholas; Davison, Brian; Beevers, Sean D; Karl, Thomas G

    2016-07-18

    To date, direct validation of city-wide emissions inventories for air pollutants has been difficult or impossible. However, recent technological innovations now allow direct measurement of pollutant fluxes from cities, for comparison with emissions inventories, which are themselves commonly used for prediction of current and future air quality and to help guide abatement strategies. Fluxes of NOx were measured using the eddy-covariance technique from an aircraft flying at low altitude over London. The highest fluxes were observed over central London, with lower fluxes measured in suburban areas. A footprint model was used to estimate the spatial area from which the measured emissions occurred. This allowed comparison of the flux measurements to the UK's National Atmospheric Emissions Inventory (NAEI) for NOx, with scaling factors used to account for the actual time of day, day of week and month of year of the measurement. The comparison suggests significant underestimation of NOx emissions in London by the NAEI, mainly due to its under-representation of real world road traffic emissions. A comparison was also carried out with an enhanced version of the inventory using real world driving emission factors and road measurement data taken from the London Atmospheric Emissions Inventory (LAEI). The measurement to inventory agreement was substantially improved using the enhanced version, showing the importance of fully accounting for road traffic, which is the dominant NOx emission source in London. In central London there was still an underestimation by the inventory of 30-40% compared with flux measurements, suggesting significant improvements are still required in the NOx emissions inventory. PMID:27098421

  7. Near-infrared spatially resolved spectroscopy of (136108) Haumea's multiple system

    NASA Astrophysics Data System (ADS)

    Gourgeot, F.; Carry, B.; Dumas, C.; Vachier, F.; Merlin, F.; Lacerda, P.; Barucci, M. A.; Berthier, J.

    2016-08-01

    Context. The transneptunian region of the solar system is populated by a wide variety of icy bodies showing great diversity in orbital behavior, size, surface color, and composition. Aims: The dwarf planet (136108) Haumea is among the largest transneptunian objects (TNOs) and is a very fast rotator (~3.9 h). This dwarf planet displays a highly elongated shape and hosts two small moons that are covered with crystalline water ice, similar to their central body. A particular region of interest is the Dark Red Spot (DRS) identified on the surface of Haumea from multiband light-curve analysis (Lacerda et al. 2008). Haumea is also known to be the largest member of the sole TNO family known to date, and an outcome of a catastrophic collision that is likely responsible for the unique characteristics of Haumea. Methods: We report here on the analysis of a new set of near-infrared Laser Guide Star assisted observations of Haumea obtained with the Integral Field Unit (IFU) Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) at the European Southern Observatory (ESO) Very Large Telescope (VLT) Observatory. Combined with previous data published by Dumas et al. (2011), and using light-curve measurements in the optical and far infrared to associate each spectrum with its corresponding rotational phase, we were able to carry out a rotationally resolved spectroscopic study of the surface of Haumea. Results: We describe the physical characteristics of the crystalline water ice present on the surface of Haumea for both regions, in and out of the DRS, and analyze the differences obtained for each individual spectrum. The presence of crystalline water ice is confirmed over more than half of the surface of Haumea. Our measurements of the average spectral slope (1.45 ± 0.82% by 100 nm) confirm the redder characteristic of the spot region. Detailed analysis of the crystalline water-ice absorption bands do not show significant differences between the DRS and the

  8. A Concept for the Development of Spatially Resolved Measurements for Soil Moisture with TEM Waveguides

    NASA Astrophysics Data System (ADS)

    Lapteva, Yulia; Schmidt, Felix; Bumberger, Jan

    2014-05-01

    Soil water content plays a leading role in delimitating water and energy fluxes at the land surface and controlling groundwater recharging. The information about water content in the soil would be very useful in overcoming the challenge of managing water resources under conditions of increasing scarcity in Southern Europe and the Mediterranean region.For collecting data about the water content in soil, it is possible to use remote sensing and groundwater monitoring, built wireless sensor networks for water monitoring. Remote sensing provides a unique capability to get the information of soil moisture at global and regional scales. Wireless environmental sensor networks enable to connect local and regional-scale soil water content observations. There exist different ground based soil moisture measurement methods such as TDR, FDR, electromagnetic waves (EW), electrical and acoustic methods. Among these methods, the time domain reflectometry (TDR) is considered to be the most important and widely used electromagnetic approach. The special techniques for the reconstruction of the layered soil with TDR are based on differential equations in the time domain and numerical optimization algorithms. However, these techniques are time- consuming and suffering from some problems, like multiple reflections at the boundary surfaces. To overcome these limitations, frequency domain measurement (FDM) techniques could be used. With devices like vector network analyzers (VNA) the accuracy of the measurement itself and of the calibration can be improved. For field applicable methods the reflection coefficient is mathematically transformed in the time domain, which can be treated like TDR-data and the same information can be obtained. There are already existed some experiments using the frequency domain data directly as an input for inversion algorithms to find the spatial distribution of the soil parameters. The model that is used represents an exact solution of the Maxwell

  9. Spatially Resolved WFC3/Grism Spectral Line Imaging of Gravitational Lensed Herschel-selected Luminous Dusty Starbursts

    NASA Astrophysics Data System (ADS)

    Cooray, Asantha

    2013-10-01

    We propose WFC3 G102 and G141 grism spectral imaging of two gravitationally lensed dusty, starburst galaxies found with the 600 square degree Herschel-ATLAS survey. One galaxy is the brightest {both in far-IR at 250 micron and in near-IR in J/K-band}, while the second is the largest {11 arcsec on the sky} of the lensed sub-mm galaxies in a sample of 200 imaged with WFC3/F110W. The two galaxies are at redshifts that are optimal for grism observations with HST/WFC3. The lensing flux magnification and spatial enhancement makes them very unique for the study proposed hereand will increase the number of lensed galaxies imaged in spectral lines with WFC3 grisms to three from existing single serendipitous lens studied in HST-3D survey. With WFC3 grism spectra taken in a specific orientation to minimize foreground and lensing galaxy confusion we can map each of these galaxies in a variety of spatially-resolved spectral lines in the rest-frame optical, including impostant Balmer lines for studies on the interstellar medium. The grism spectra will allow us to determine the gas-phase metallicities of these two galaxies and to study the extinction of optically-thin regions compared to direct sub-mm emission seen in interferometric continuum images of optically thick dust in starbursting knots and clumps. With spatial resolution provided by gravitational lensing combined with HST/WFC3 resolution, we will be able to study the dependence of line ratios in high density/SFR regions to low dense diffuse environments.

  10. Analysis for nonlinear inversion technique developed to estimate depth-distribution of absorption by spatially resolved backscattering measurement

    NASA Astrophysics Data System (ADS)

    Nishida, Kazuhiro; Namita, Takeshi; Kato, Yuji; Shimizu, Koichi

    2015-03-01

    We have proposed a new nonlinear inversion technique to estimate the spatial distribution of the absorption coefficient (μa) in the depth direction of a turbid medium by spatially resolved backscattering measurement. With this technique, we can obtain cross-sectional image of μa as deep as the backscattered light traveled even when the transmitted light through the medium cannot be detected. In this technique, the depth distribution of absorption coefficient is determined by iterative calculation using the spatial path-length distribution (SPD) of traveled photons as a function of source-detector distance. In this calculation, the variance of path-length of many photons in each layer is also required. The SPD and the variance of path-length are obtained by Monte Carlo simulation using a known reduced scattering coefficient (μs'). Therefore, we need to know the μs' of the turbid medium beforehand. We have shown in computer simulation that this technique works well when the μs' is the typical values of mammalian body tissue, or 1.0 /mm. In this study, the accuracy of the μa estimation was analyzed and its dependence on the μs' was clarified quantitatively in various situations expected in practice. 10% deviations in μs' resulted in about 30% error in μa estimation, in average. This suggested that the measurement or the appropriate estimation of μs' is required to utilize the proposed technique effectively. Through this analysis, the effectiveness and the limitation of the newly proposed technique were clarified, and the problems to be solved were identified.

  11. Spatially Resolved, In Situ Carbon Isotope Analysis of Archean Organic Matter

    NASA Technical Reports Server (NTRS)

    Williford, Kenneth H.; Ushikubo, Takayuki; Lepot, Kevin; Hallmann, Christian; Spicuzza, Michael J.; Eigenbrode, Jennifer L.; Summons, Roger E.; Valley, John W.

    2011-01-01

    Spatiotemporal variability in the carbon isotope composition of sedimentary organic matter (OM) preserves information about the evolution of the biosphere and of the exogenic carbon cycle as a whole. Primary compositions, and imprints of the post-depositional processes that obscure them, exist at the scale of individual sedimentary grains (mm to micron). Secondary ion mass spectrometry (SIMS) (1) enables analysis at these scales and in petrographic context, (2) permits morphological and compositional characterization of the analyte and associated minerals prior to isotopic analysis, and (3) reveals patterns of variability homogenized by bulk techniques. Here we present new methods for in situ organic carbon isotope analysis with sub-permil precision and spatial resolution to 1 micron using SIMS, as well as new data acquired from a suite of Archean rocks. Three analytical protocols were developed for the CAMECA ims1280 at WiscSIMS to analyze domains of varying size and carbon concentration. Average reproducibility (at 2SD) using a 6 micron spot size with two Faraday cup detectors was 0.4 %, and 0.8 % for analyses using 1 micron and 3 micron spot sizes with a Faraday cup (for C-12) and an electron multiplier (for C-13). Eight coals, two ambers, a shungite, and a graphite were evaluated for micron-scale isotopic heterogeneity, and LCNN anthracite (delta C-13 = -23.56 +/- 0.1 %, 2SD) was chosen as the working standard. Correlation between instrumental bias and H/C was observed and calibrated for each analytical session using organic materials with H/C between 0.1 and 1.5 (atomic), allowing a correction based upon a C-13H/C-13 measurement included in every analysis. Matrix effects of variable C/SiO2 were evaluated by measuring mm to sub-micron graphite domains in quartzite from Bogala mine, Sri Lanka. Apparent instrumental bias and C-12 count rate are correlated in this case, but this may be related to a crystal orientation effect in graphite. Analyses of amorphous

  12. The Panchromatic Hubble Andromeda Treasury. XI. The Spatially Resolved Recent Star Formation History of M31

    NASA Astrophysics Data System (ADS)

    Lewis, Alexia R.; Dolphin, Andrew E.; Dalcanton, Julianne J.; Weisz, Daniel R.; Williams, Benjamin F.; Bell, Eric F.; Seth, Anil C.; Simones, Jacob E.; Skillman, Evan D.; Choi, Yumi; Fouesneau, Morgan; Guhathakurta, Puragra; Johnson, Lent C.; Kalirai, Jason S.; Leroy, Adam K.; Monachesi, Antonela; Rix, Hans-Walter; Schruba, Andreas

    2015-06-01

    We measure the recent star formation history (SFH) across M31 using optical images taken with the Hubble Space Telescope as part of the Panchromatic Hubble Andromeda Treasury (PHAT). We fit the color-magnitude diagrams in ˜9000 regions that are ˜100 pc × 100 pc in projected size, covering a 0.5 square degree area (˜380 kpc2, deprojected) in the NE quadrant of M31. We show that the SFHs vary significantly on these small spatial scales but that there are also coherent galaxy-wide fluctuations in the SFH back to ˜500 Myr, most notably in M31's 10 kpc star-forming ring. We find that the 10 kpc ring is at least 400 Myr old, showing ongoing star formation (SF) over the past ˜500 Myr. This indicates the presence of molecular gas in the ring over at least 2 dynamical times at this radius. We also find that the ring’s position is constant throughout this time, and is stationary at the level of 1 km s-1, although there is evidence for broadening of the ring due to the diffusion of stars into the disk. Based on existing models of M31's ring features, the lack of evolution in the ring’s position makes a purely collisional ring origin highly unlikely. Besides the well-known 10 kpc ring, we observe two other ring-like features. There is an outer ring structure at 15 kpc with concentrated SF starting ˜80 Myr ago. The inner ring structure at 5 kpc has a much lower star formation rate (SFR) and therefore lower contrast against the underlying stellar disk. It was most clearly defined ˜200 Myr ago, but is much more diffuse today. We find that the global SFR has been fairly constant over the last ˜500 Myr, though it does show a small increase at 50 Myr that is 1.3 times the average SFR over the past 100 Myr. During the last ˜500 Myr, ˜60% of all SF has occurred in the 10 kpc ring. Finally, we find that in the past 100 Myr, the average SFR over the PHAT survey area is 0.28 ± 0.03 {{M}⊙ } y{{r}-1} with an average deprojected intensity of 7.3× {{10}-4} {{M}⊙ } y

  13. Joint derivation method for determining optical properties based on steady-state spatially resolved diffuse reflectance measurement at small source-detector separations and large reduced albedo range: theory and simulation.

    PubMed

    Shi, Zhenzhi; Fan, Ying; Zhao, Huijuan; Xu, Kexin

    2012-06-01

    Accurate determination of the optical properties (the absorption coefficient μ(a) and the reduced scattering coefficient μ(s) (')) of tissues is very important in a variety of diagnostic and therapeutic procedures. Optical diffusion theory is frequently used as the forward model for describing the photon transfer in media with large reduced albedos (a(')) and in large source-detector separations (SDS). Several other methods (PN approximation, hybrid diffusion-P3 approximation) have also been published that describe photon transfer in media with low a(') or small SDSs. We studied the theoretical models for the steady-state spatially resolved diffuse reflectance measurement to accurately determine μ(a) and μ(s) (') at large a(') range but small SDSs. Instead of using a single model, a joint derivation method is proposed. The developed method uses one of the best aforementioned theoretical methods separately in five ranges of a(') determined from several forward models. In the region of small SDSs (the range between 0.4 and 8 mm) and large a(') range (between 0.5 and 0.99), the best theoretical derivation model was determined. The results indicate that the joint derivation method can improve the derivation accuracy and that a(') range can be determined by the steady-state spatially resolved diffuse reflectance measurement. PMID:22734782

  14. Spatially Resolved Genomic, Stable Isotopic, and Lipid Analyses of a Modern Freshwater Microbialite from Cuatro Ciénegas, Mexico

    PubMed Central

    Nitti, Anthony; Daniels, Camille A.; Siefert, Janet; Souza, Valeria; Hollander, David

    2012-01-01

    Abstract Microbialites are biologically mediated carbonate deposits found in diverse environments worldwide. To explore the organisms and processes involved in microbialite formation, this study integrated genomic, lipid, and both organic and inorganic stable isotopic analyses to examine five discrete depth horizons spanning the surface 25 mm of a modern freshwater microbialite from Cuatro Ciénegas, Mexico. Distinct bacterial communities and geochemical signatures were observed in each microbialite layer. Photoautotrophic organisms accounted for approximately 65% of the sequences in the surface community and produced biomass with distinctive lipid biomarker and isotopic (δ13C) signatures. This photoautotrophic biomass was efficiently degraded in the deeper layers by heterotrophic organisms, primarily sulfate-reducing proteobacteria. Two spatially distinct zones of carbonate precipitation were observed within the microbialite, with the first zone corresponding to the phototroph-dominated portion of the microbialite and the second zone associated with the presence of sulfate-reducing heterotrophs. The coupling of photoautotrophic production, heterotrophic decomposition, and remineralization of organic matter led to the incorporation of a characteristic biogenic signature into the inorganic CaCO3 matrix. Overall, spatially resolved multidisciplinary analyses of the microbialite enabled correlations to be made between the distribution of specific organisms, precipitation of carbonate, and preservation of unique lipid and isotopic geochemical signatures. These findings are critical for understanding the formation of modern microbialites and have implications for the interpretation of ancient microbialite records. Key Words: Microbial ecology—Microbe-mineral interactions—Microbial mats—Stromatolites—Genomics. Astrobiology 12, 685–698. PMID:22882001

  15. A SCR Model Calibration Approach with Spatially Resolved Measurements and NH3 Storage Distributions

    SciTech Connect

    Song, Xiaobo; Parker, Gordon G.; Johnson, John H.; Naber, Jeffrey D.; Pihl, Josh A.

    2014-11-27

    The selective catalytic reduction (SCR) is a technology used for reducing NO x emissions in the heavy-duty diesel (HDD) engine exhaust. In this study, the spatially resolved capillary inlet infrared spectroscopy (Spaci-IR) technique was used to study the gas concentration and NH3 storage distributions in a SCR catalyst, and to provide data for developing a SCR model to analyze the axial gaseous concentration and axial distributions of NH3 storage. A two-site SCR model is described for simulating the reaction mechanisms. The model equations and a calculation method was developed using the Spaci-IR measurements to determine the NH3 storage capacity and the relationships between certain kinetic parameters of the model. Moreover, a calibration approach was then applied for tuning the kinetic parameters using the spatial gaseous measurements and calculated NH3 storage as a function of axial position instead of inlet and outlet gaseous concentrations of NO, NO2, and NH3. The equations and the approach for determining the NH3 storage capacity of the catalyst and a method of dividing the NH3 storage capacity between the two storage sites are presented. It was determined that the kinetic parameters of the adsorption and desorption reactions have to follow certain relationships for the model to simulate the experimental data. Finally, the modeling results served as a basis for developing full model calibrations to SCR lab reactor and engine data and state estimator development as described in the references (Song et al. 2013a, b; Surenahalli et al. 2013).

  16. Discovery of a Strongly Lensed Massive Quiescent Galaxy at z = 2.636: Spatially Resolved Spectroscopy and Indications of Rotation

    NASA Astrophysics Data System (ADS)

    Newman, Andrew B.; Belli, Sirio; Ellis, Richard S.

    2015-11-01

    We report the discovery of RG1M0150, a massive, recently quenched galaxy at z = 2.636 that is multiply imaged by the cluster MACSJ0150.3-1005. We derive a stellar mass of {log}{M}*={11.49}-0.16+0.10 and a half-light radius of {R}e,{maj}=1.8+/- 0.4 {{kpc}}. Taking advantage of the lensing magnification, we are able to spatially resolve a remarkably massive yet compact quiescent galaxy at z\\gt 2 in ground-based near-infrared spectroscopic observations using Magellan/FIRE and Keck/MOSFIRE. We find no gradient in the strength of the Balmer absorption lines over 0.6{R}e-1.6{R}e, which are consistent with an age of 760 Myr. Gas emission in [N ii] broadly traces the spatial distribution of the stars and is coupled with weak Hα emission (log [N ii]/{{H}}α =0.6+/- 0.2), indicating that OB stars are not the primary ionizing source. The velocity dispersion within the effective radius is {σ }e,{stars}=271+/- 41 km s{}-1. We detect rotation in the stellar absorption lines for the first time beyond z∼ 1. Using a two-integral Jeans model that accounts for observational effects, we measure a dynamical mass of {log}{M}{{dyn}}=11.24+/- 0.14 and V/σ =0.70+/- 0.21. This is a high degree of rotation considering the modest observed ellipticity of 0.12 ± 0.08, but it is consistent with predictions from dissipational merger simulations that produce compact remnants. The mass of RG1M0150 implies that it is likely to become a slowly rotating elliptical. If it is typical, this suggests that the progenitors of massive ellipticals retain significant net angular momentum after quenching which later declines, perhaps through accretion of satellites.

  17. Quantification of the Optical Properties of Two-Layer Turbid Materials Using a Hyperspectral Imaging-based Spatially-resolved Technique

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent research has shown that a hyperspectral imaging-based spatially-resolved technique is useful for determining the optical properties of homogeneous fruits and food products. To better characterize fruit properties and quality attributes, it is desirable to consider fruit to be composed of two ...

  18. Spatially resolved, in-situ monitoring of crack growth via the coupling current in aluminum alloy 5083

    NASA Astrophysics Data System (ADS)

    Williams, Krystaufeux D.

    The work discussed in this dissertation is an experimental validation of a body of research that was created to model stress corrosion cracking phenomenon for 304 stainless steels in boiling water reactors. This coupled environment fracture model (CEFM) incorporates the natural laws of the conservation of charge and the differential aeration hypothesis to predict the amount of stress corrosion crack growth as a function of many external environmental variables, including potential, stress intensity, solution conductivity, oxidizer concentrations, and various other environmental parameters. Out of this approach came the concept of the coupling current; a local corrosion current that flows from within cracks, crevices, pits, etc... of a metal or alloy to the external surface. Because of the deterministic approach taken in the mentioned research, the coupling current analysis and CEFM model can be applied to the specific problem of SCC in aluminum alloy 5083 (the alloy of interest for this dissertation that is highly sought after today because of its corrosion resistance and high strength to weight ratio). This dissertation research is specifically devoted to the experimental verification of the coupling current, which results from a coupling between the crack's internal and external environments, by spatially resolving them using the scanning vibrating probe (SVP) as a tool. Hence, through the use of a unique fracture mechanics setup, simultaneous mechanical and local electrochemical data may be obtained, in situ..

  19. The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII): Spatially Resolved Spectroscopy in the Far-Infrared

    NASA Technical Reports Server (NTRS)

    Rinehart, Stephen

    2009-01-01

    Astronomical studies at infrared wavelengths have dramatically improved our understanding of the universe, and observations with Spitzer, the upcoming Herschel mission, and SOFIA will continue to provide exciting new discoveries. The relatively low angular resolution of these missions, however, is insufficient to resolve the physical scale on which mid-to far-infrared emission arises, resulting in source and structure ambiguities that limit our ability to answer key science questions. Interferometry enables high angular resolution at these wavelengths - a powerful tool for scientific discovery. We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII), an eight-meter baseline Michelson stellar interferometer to fly on a high-altitude balloon. BETTII's spectral-spatial capability, provided by an instrument using double-Fourier techniques, will address key questions about the nature of disks in young star clusters and active galactic nuclei and the envelopes of evolved stars. BETTII will also lay the technological groundwork for future space interferometers and for suborbital programs optimized for studying extrasolar planets.

  20. Spatially resolved physical conditions of molecular gas: a zoom-in from circumnuclear region of M83 to Carina nebula.

    NASA Astrophysics Data System (ADS)

    Wu, Ronin; Madden, Suzanne; Galliano, Frédéric; Wilson, Christine; Onaka, Takashi; Nakamura, Tomohiko

    2015-08-01

    Since the launch of the Herschel Space Observatory, our understanding about the photo-dissociation regions (PDR) has taken a step forward. In the bandwidth of the Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) on board Herschel, ten CO rotational transitions, including J=4-3 to J=13-12, and three fine structure lines, including [CI] 609, [CI] 370, and [NII] 250 micron, are covered. This presentation focuses on the physical conditions of molecular gas probed by the Herschel SPIRE/FTS.Based on the spatially resolved physical parameters derived from the CO spectral line energy distribution (SLED) map and the comparisons with the dust properties and star-formation tracers, I will first present our findings at the circumnuclear region of M83, and then zoom in toward the young open cluster, Trumpler 14, in Carina nebula. I will discuss (1) the potential of using [NII] 250 and [CI] 370 micron as star-formation tracers; (2) the reliability of tracing molecular gas with CO; (3) the excitation mechanisms of warm CO; (4) the possibility of studying stellar feedback by tracing the thermal pressure of intersetllar molecular gas.

  1. Solid-State Selective 13C Excitation and Spin Diffusion NMR to Resolve Spatial Dimensions in Plant Cell Walls

    SciTech Connect

    Foston, M.; Katahira, R.; Gjersing, E.; Davis, M. F.; Ragauskas, A. J.

    2012-02-15

    The average spatial dimensions between major biopolymers within the plant cell wall can be resolved using a solid-state NMR technique referred to as a {sup 13}C cross-polarization (CP) SELDOM (selectively by destruction of magnetization) with a mixing time delay for spin diffusion. Selective excitation of specific aromatic lignin carbons indicates that lignin is in close proximity to hemicellulose followed by amorphous and finally crystalline cellulose. {sup 13}C spin diffusion time constants (T{sub SD}) were extracted using a two-site spin diffusion theory developed for {sup 13}C nuclei under magic angle spinning (MAS) conditions. These time constants were then used to calculate an average lower-limit spin diffusion length between chemical groups within the plant cell wall. The results on untreated {sup 13}C enriched corn stover stem reveal that the lignin carbons are, on average, located at distances {approx}0.7-2.0 nm from the carbons in hemicellulose and cellulose, whereas the pretreated material had larger separations.

  2. Time and spatially resolved LIF of OH in a plasma filament in atmospheric pressure He-H2O

    NASA Astrophysics Data System (ADS)

    Verreycken, T.; van der Horst, R. M.; Baede, A. H. F. M.; Van Veldhuizen, E. M.; Bruggeman, P. J.

    2012-02-01

    The production of OH in a nanosecond pulsed filamentary discharge generated in pin-pin geometry in a He-H2O mixture is studied by time and spatially resolved laser-induced fluorescence. Apart from the OH density the gas temperature and the electron density are also measured. Depending on the applied voltage the discharge is in a different mode. The maximum electron densities in the low- (1.3 kV) and high-density (5 kV) modes are 2 × 1021 m-3 and 7 × 1022 m-3, respectively. The gas temperature in both modes does not exceed 600 K. In the low-density mode the maximum OH density is at the centre of the discharge filament, while in the high-density mode the largest OH density is observed on the edge of the discharge. A chemical model is used to obtain an estimate of the absolute OH density. The chemical model also shows that charge exchange and dissociative recombination can explain the production of OH in the case of the high-density mode.

  3. Computer simulation of the distribution of hexane in a lipid bilayer: spatially resolved free energy, entropy, and enthalpy profiles.

    PubMed

    MacCallum, Justin L; Tieleman, D Peter

    2006-01-11

    The partitioning behavior of small molecules in lipid bilayers is important in a variety of areas including membrane protein folding and pharmacology. However, the inhomogeneous nature of lipid bilayers on a nanometer length scale complicates experimental studies of membrane partitioning. To gain more insight in the partitioning of a small molecule into the lipid bilayer, we have carried out atomistic computer simulations of hexane in a dioleoyl phosphatidylcholine model membrane. We have been able to obtain spatially resolved free energy, entropy, enthalpy, and heat capacity profiles based on umbrella sampling calculations at three different temperatures. In agreement with experiment, hexane partitions preferentially to the center of the bilayer. This process is driven almost entirely by a favorable entropy change, consistent with the hydrophobic effect. In contrast, partitioning to the densest region of the acyl chains is dominated by a favorable enthalpy change with a small entropy change, which is consistent with the "nonclassical" hydrophobic effect or "bilayer" effect. We explain the features of the entropy and enthalpy profiles in terms of density and free volume in the system. PMID:16390139

  4. Spatially-Resolved Analysis of Glycolipids and Metabolites in Living Synechococcus sp. PCC7002 Using Nanospray Desorption Electrospray Ionization

    SciTech Connect

    Lanekoff, Ingela T.; Geydebrekht, Oleg V.; Pinchuk, Grigoriy E.; Konopka, Allan; Laskin, Julia

    2013-04-07

    Microorganisms release a diversity of organic compounds that couple interspecies metabolism, enable communication, or provide benefits to other microbes. Increased knowledge of microbial metabolite production will contribute to understanding of the dynamic microbial world and can potentially lead to new developments in drug discovery, biofuel production, and clinical research. Nanospray desorption electrospray ionization (nano-DESI) is an ambient ionization technique that enables detailed chemical characterization of molecules from a specific location on a surface without special sample pretreatment. Due to its ambient nature, living bacterial colonies growing on agar plates can be rapidly and non-destructively analyzed. We performed spatially resolved nano-DESI analysis of living Synechococcus sp. PCC 7002 colonies on agar plates. We use high resolution mass spectrometry and MS/MS analysis of the living Synechococcus sp. PCC 7002 colonies to detect metabolites and lipids, and confirm their identities. We found that despite the high salt content of the agar (osmolarity ca. 700 mM), nano-DESI analysis enables detailed characterization of metabolites produced by the colony. Using this technique, we identified several glycolipids found on the living colonies and examined the effect of the age of the colony on the chemical gradient of glucosylglycerol secreted onto agar.

  5. Localization of an absorber in a turbid semi-infinite medium by spatially resolved continuous-wave diffuse reflectance measurements

    NASA Astrophysics Data System (ADS)

    Aksel, Ertugrul Burtecin; Turkoglu, Ahu Nur; Ercan, Ayse Ece; Akin, Ata

    2011-08-01

    A method to locate an absorber embedded in a semi-infinite turbid medium by spatially-resolved continuous-wave (SRCW) diffuse reflectance measurements is introduced. The depth of the absorber is assessed by single wavelength SRCW diffuse reflectance measurements by two detectors in a radial row. The ratio of perturbations introduced by the defect at two detectors is used to be matched with the ratio-versus-depth curve, which are generated by approximate formulas of continuous wave diffuse reflectance. The error due to approximation and the error in depth assessment are studied for different cases revealing favorable source-detector placements with respect to planar position of the defect. The effect of lateral displacement of the source with respect to defect is studied. A strategy to overcome errors introduced by erroneous prediction of background medium optical properties is suggested. Theoretical results indicate that the depth of the absorber can be obtained with 0.1 mm precision independent of its absorption coefficient and its size for the values chosen in the study. The approach is tested experimentally and it is observed that theoretical results fit with experimental data.

  6. HST Spatially Resolved Spectra of the Accretion Disc and Gas Stream of the Nova-Like Variable UX Ursae Majoris

    NASA Technical Reports Server (NTRS)

    Baptista, Raymundo; Horne, Keith; Wade, Richard A.; Hubeny, Ivan; Long, Knox S.; Rutten, Rene G. M.

    1998-01-01

    Time-resolved eclipse spectroscopy of the nova-like variable UX UMa obtained with the Hubble Space Telescope/Faint Object Spectrograph (HST/FOS) on 1994 August and November is analysed with eclipse mapping techniques to produce spatially resolved spectra of its accretion disk and gas stream as a function of distance from the disk centre. The inner accretion disk is characterized by a blue continuum filled with absorption bands and lines, which cross over to emission with increasing disk radius, similar to that reported at optical wavelengths. The comparison of spatially resolved spectra at different azimuths reveals a significant asymmetry in the disk emission at ultraviolet (UV) wavelengths, with the disk side closest to the secondary star showing pronounced absorption by an 'iron curtain' and a Balmer jump in absorption. These results suggest the existence of an absorbing ring of cold gas whose density and/or vertical scale increase with disk radius. The spectrum of the infalling gas stream is noticeably different from the disc spectrum at the same radius suggesting that gas overflows through the impact point at the disk rim and continues along the stream trajectory, producing distinct emission down to 0.1 R(sub LI). The spectrum of the uneclipsed light shows prominent emission lines of Lyalpha, N v lambda1241, SiIV Lambda 1400, C IV Lambda 1550, HeII Lambda 1640, and MgII Lambda 2800, and a UV continuum rising towards longer wavelengths. The Balmer jump appears clearly in emission indicating that the uneclipsed light has an important contribution from optically thin gas. The lines and optically thin continuum emission are most probably emitted in a vertically extended disk chromosphere + wind. The radial temperature profiles of the continuum maps are well described by a steady-state disc model in the inner and intermediate disk regions (R greater than or equal to 0.3R(sub LI) ). There is evidence of an increase in the mass accretion rate from August to November

  7. Exploratory studies of PM10 receptor and source profiling by GC/MS and principal component analysis of temporally and spatially resolved ambient samples.

    PubMed

    Jeon, S J; Meuzelaar, H L; Sheya, S A; Lighty, J S; Jarman, W M; Kasteler, C; Sarofim, A F; Simoneit, B R

    2001-05-01

    For a recent exploratory study of particulate matter (PM) compositions, origins, and impacts in the El Paso/Juarez (Paso del Norte) airshed, the authors relied on solvent extraction (SX)-gas chromatography/mass spectrometry (GC/MS) procedures to characterize 24-hr quartz fiber (QF) filter samples obtained from nine spatially distributed high-volume (Hi-Vol) PM10 samplers as well as on thermal desorption (TD)-GC/MS methods to characterize 45 time-resolved (2-hr) filter samples obtained with modified 1-m3/hr PM10 samplers. Principal component analysis and related chemometric techniques were used for data reduction and data fusion as well as for multiway data correlation. A high degree of correspondence (R2 = 0.821) was found between the rapid TD-GC/MS method (which can be carried out on 2-hr filter slices containing only microgram amounts of sample) and conventional SX-GC/MS procedures. The four main source patterns of organic PM components observed in GC/MS profiles of both temporally and spatially resolved receptor samples obtained in the El Paso/Juarez border airshed during the study period are interpreted to represent (1) vehicular emissions plus resuspended urban dust; (2) biomass combustion; (3) native vegetation detritus and resuspended agricultural dust; and (4) waste burning. Moreover, principal component analysis of combined, variance-weighted, temporally resolved TD-GC/MS data and spatially resolved SX-GC/MS data was used to determine approximate source locations for specific PM components identified in time-resolved receptor sample profiles. The same approach can be used to determine approximate circadian concentration profiles of specific PM components identified in spatially resolved receptor sample profiles. PMID:11355465

  8. A Spatially Resolving X-ray Crystal Spectrometer for Measurement of Ion-temperature and Rotation-velocity Profiles on the AlcatorC-Mod Tokamak

    SciTech Connect

    Hill, K. W.; Bitter, M. L.; Scott, S. D.; Ince-Cushman, A.; Reinke, M.; Rice, J. E.; Beiersdorfer, P.; Gu, M. F.; Lee, S. G.; Broennimann, C. H.; Eikenberry, E. F.

    2009-03-24

    A new spatially resolving x-ray crystal spectrometer capable of measuring continuous spatial profiles of high resolution spectra (λ/dλ > 6000) of He-like and H-like Ar Kα lines with good spatial (~1 cm) and temporal (~10 ms) resolutions has been installed on the Alcator C-Mod tokamak. Two spherically bent crystals image the spectra onto four two-dimensional Pilatus II pixel detectors. Tomographic inversion enables inference of local line emissivity, ion temperature (Ti), and toroidal plasma rotation velocity (vφ) from the line Doppler widths and shifts. The data analysis techniqu

  9. Spatially resolved quantification of gadolinium(III)-based magnetic resonance agents in tissue by MALDI imaging mass spectrometry after in vivo MRI.

    PubMed

    Aichler, Michaela; Huber, Katharina; Schilling, Franz; Lohöfer, Fabian; Kosanke, Katja; Meier, Reinhard; Rummeny, Ernst J; Walch, Axel; Wildgruber, Moritz

    2015-03-27

    Gadolinium(III)-based contrast agents improve the sensitivity and specificity of magnetic resonance imaging (MRI), especially when targeted contrast agents are applied. Because of nonlinear correlation between the contrast agent concentration in tissue and the MRI signal obtained in vivo, quantification of certain biological or pathophysiological processes by MRI remains a challenge. Up to now, no technology has been able to provide a spatially resolved quantification of MRI agents directly within the tissue, which would allow a more precise verification of in vivo imaging results. MALDI imaging mass spectrometry for spatially resolved in situ quantification of gadolinium(III) agents, in correlation to in vivo MRI, were evaluated. Enhanced kinetics of Gadofluorine M were determined dynamically over time in a mouse model of myocardial infarction. MALDI imaging was able to corroborate the in vivo imaging MRI signals and enabled in situ quantification of the gadolinium probe with high spatial resolution. PMID:25689595

  10. Spatially resolved analysis of plutonium isotopic signatures in environmental particle samples by laser ablation-MC-ICP-MS.

    PubMed

    Konegger-Kappel, Stefanie; Prohaska, Thomas

    2016-01-01

    Laser ablation-multi-collector-inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) was optimized and investigated with respect to its performance for determining spatially resolved Pu isotopic signatures within radioactive fuel particle clusters. Fuel particles had been emitted from the Chernobyl nuclear power plant (ChNPP) where the 1986 accident occurred and were deposited in the surrounding soil, where weathering processes caused their transformation into radioactive clusters, so-called micro-samples. The size of the investigated micro-samples, which showed surface alpha activities below 40 mBq, ranged from about 200 to 1000 μm. Direct single static point ablations allowed to identify variations of Pu isotopic signatures not only between distinct fuel particle clusters but also within individual clusters. The resolution was limited to 100 to 120 μm as a result of the applied laser ablation spot sizes and the resolving power of the nuclear track radiography methodology that was applied for particle pre-selection. The determined (242)Pu/(239)Pu and (240)Pu/(239)Pu isotope ratios showed a variation from low to high Pu isotope ratios, ranging from 0.007(2) to 0.047(8) for (242)Pu/(239)Pu and from 0.183(13) to 0.577(40) for (240)Pu/(239)Pu. In contrast to other studies, the applied methodology allowed for the first time to display the Pu isotopic distribution in the Chernobyl fallout, which reflects the differences in the spent fuel composition over the reactor core. The measured Pu isotopic signatures are in good agreement with the expected Pu isotopic composition distribution that is typical for a RBMK-1000 reactor, indicating that the analyzed samples are originating from the ill-fated Chernobyl reactor. The average Pu isotope ratios [(240)Pu/(239)Pu = 0.388(86), (242)Pu/(239)Pu = 0.028(11)] that were calculated from all investigated samples (n = 48) correspond well to previously published results of Pu analyses in contaminated samples from

  11. Accurate Memory for Object Location by Individuals with Intellectual Disability: Absolute Spatial Tagging Instead of Configural Processing?

    ERIC Educational Resources Information Center

    Giuliani, Fabienne; Favrod, Jerome; Grasset, Francois; Schenk, Francoise

    2011-01-01

    Using head-mounted eye tracker material, we assessed spatial recognition abilities (e.g., reaction to object permutation, removal or replacement with a new object) in participants with intellectual disabilities. The "Intellectual Disabilities (ID)" group (n = 40) obtained a score totalling a 93.7% success rate, whereas the "Normal Control" group…

  12. Late Enrichment Maintains Accurate Recent and Remote Spatial Memory Only in Aged Rats That Were Unimpaired When Middle Aged

    ERIC Educational Resources Information Center

    Fuchs, Fanny; Herbeaux, Karine; Aufrere, Noémie; Kelche, Christian; Mathis, Chantal; Barbelivien, Alexandra; Majchrzak, Monique

    2016-01-01

    Exposure of rodents to a stimulating environment has beneficial effects on some cognitive functions that are impaired during physiological aging, and especially spatial reference memory. The present study investigated whether environmental enrichment rescues these functions in already declining subjects and/or protects them from subsequent…

  13. SPATIALLY RESOLVED OBSERVATIONS OF THE BIPOLAR OPTICAL OUTFLOW FROM THE BROWN DWARF 2MASS J12073347-3932540

    SciTech Connect

    Whelan, E. T.; Ray, T. P.; Comeron, F.; Bacciotti, F.; Kavanagh, P. J.

    2012-12-20

    Studies of brown dwarf (BD) outflows provide information pertinent to questions on BD formation, as well as allowing outflow mechanisms to be investigated at the lowest masses. Here new observations of the bipolar outflow from the 24 M{sub JUP} BD 2MASS J12073347-3932540 are presented. The outflow was originally identified through the spectro-astrometric analysis of the [O I]{lambda}6300 emission line. Follow-up observations consisting of spectra and [S II], R-band and I-band images were obtained. The new spectra confirm the original results and are used to constrain the outflow position angle (P.A.) at {approx}65 Degree-Sign . The [O I]{lambda}6300 emission line region is spatially resolved and the outflow is detected in the [S II] images. The detection is firstly in the form of an elongation of the point-spread function (PSF) along the direction of the outflow P.A. Four faint knot-like features (labeled A-D) are also observed to the southwest of 2MASS J12073347-3932540 along the same P.A. suggested by the spectra and the elongation in the PSF. Interestingly, D, the feature furthest from the source, is bow shaped with the apex pointing away from 2MASS J12073347-3932540. A color-color analysis allows us to conclude that at least feature D is part of the outflow under investigation while A is likely a star or galaxy. Follow-up observations are needed to confirm the origin of B and C. This is a first for a BD, as BD optical outflows have to date only been detected using spectro-astrometry. This result also demonstrates for the first time that BD outflows can be collimated and episodic.

  14. Visualizing chemical states and defects induced magnetism of graphene oxide by spatially-resolved-X-ray microscopy and spectroscopy

    PubMed Central

    Wang, Y. F.; Singh, Shashi B.; Limaye, Mukta V.; Shao, Y. C.; Hsieh, S. H.; Chen, L. Y.; Hsueh, H. C.; Wang, H. T.; Chiou, J. W.; Yeh, Y. C.; Chen, C. W.; Chen, C. H.; Ray, Sekhar C.; Wang, J.; Pong, W. F.; Takagi, Y.; Ohigashi, T.; Yokoyama, T.; Kosugi, N.

    2015-01-01

    This investigation studies the various magnetic behaviors of graphene oxide (GO) and reduced graphene oxides (rGOs) and elucidates the relationship between the chemical states that involve defects therein and their magnetic behaviors in GO sheets. Magnetic hysteresis loop reveals that the GO is ferromagnetic whereas photo-thermal moderately reduced graphene oxide (M-rGO) and heavily reduced graphene oxide (H-rGO) gradually become paramagnetic behavior at room temperature. Scanning transmission X-ray microscopy and corresponding X-ray absorption near-edge structure spectroscopy were utilized to investigate thoroughly the variation of the C 2p(π*) states that are bound with oxygen-containing and hydroxyl groups, as well as the C 2p(σ*)-derived states in flat and wrinkle regions to clarify the relationship between the spatially-resolved chemical states and the magnetism of GO, M-rGO and H-rGO. The results of X-ray magnetic circular dichroism further support the finding that C 2p(σ*)-derived states are the main origin of the magnetism of GO. Based on experimental results and first-principles calculations, the variation in magnetic behavior from GO to M-rGO and to H-rGO is interpreted, and the origin of ferromagnetism is identified as the C 2p(σ*)-derived states that involve defects/vacancies rather than the C 2p(π*) states that are bound with oxygen-containing and hydroxyl groups on GO sheets. PMID:26481557

  15. A Spatially Resolved Study of the Synchrotron Emission and Titanium in Tycho’s Supernova Remnant Using NuSTAR

    NASA Astrophysics Data System (ADS)

    Lopez, Laura A.; Grefenstette, Brian W.; Reynolds, Stephen P.; An, Hongjun; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Eriksen, Kristoffer A.; Fryer, Chris L.; Hailey, Charles J.; Harrison, Fiona A.; Madsen, Kristin K.; Stern, Daniel K.; Zhang, William W.; Zoglauer, Andreas

    2015-12-01

    We report results from deep observations (˜750 ks) of Tycho's supernova remnant (SNR) with NuSTAR. Using these data, we produce narrow-band images over several energy bands to identify the regions producing the hardest X-rays and to search for radioactive decay line emission from 44Ti. We find that the hardest (>10 keV) X-rays are concentrated in the southwest of Tycho, where recent Chandra observations have revealed high emissivity “stripes” associated with particles accelerated to the knee of the cosmic-ray spectrum. We do not find evidence of 44Ti, and we set limits on its presence and distribution within the SNR. These limits correspond to an upper-limit 44Ti mass of M44 < 2.4 × 10-4 M⊙ for a distance of 2.3 kpc. We perform a spatially resolved spectroscopic analysis of 66 regions across Tycho. We map the best-fit rolloff frequency of the hard X-ray spectra, and we compare these results to measurements of the shock expansion and ambient density. We find that the highest energy electrons are accelerated at the lowest densities and in the fastest shocks, with a steep dependence of the rolloff frequency with shock velocity. Such a dependence is predicted by models where the maximum energy of accelerated electrons is limited by the age of the SNR rather than by synchrotron losses, but this scenario requires far lower magnetic field strengths than those derived from observations in Tycho. One way to reconcile these discrepant findings is through shock obliquity effects, and future observational work is necessary to explore the role of obliquity in the particle acceleration process.

  16. Temporally and spatially resolved plasma spectroscopy in pulsed laser deposition of ultra-thin boron nitride films

    NASA Astrophysics Data System (ADS)

    Glavin, Nicholas R.; Muratore, Christopher; Jespersen, Michael L.; Hu, Jianjun; Fisher, Timothy S.; Voevodin, Andrey A.

    2015-04-01

    Physical vapor deposition (PVD) has recently been investigated as a viable, alternative growth technique for two-dimensional materials with multiple benefits over other vapor deposition synthesis methods. The high kinetic energies and chemical reactivities of the condensing species formed from PVD processes can facilitate growth over large areas and at reduced substrate temperatures. In this study, chemistry, kinetic energies, time of flight data, and spatial distributions within a PVD plasma plume ablated from a boron nitride (BN) target by a KrF laser at different pressures of nitrogen gas were investigated. Time resolved spectroscopy and wavelength specific imaging were used to identify and track atomic neutral and ionized species including B+, B*, N+, N*, and molecular species including N2*, N2+, and BN. Formation and decay of these species formed both from ablation of the target and from interactions with the background gas were investigated and provided insights into fundamental growth mechanisms of continuous, amorphous boron nitride thin films. The correlation of the plasma diagnostic results with film chemical composition and thickness uniformity studies helped to identify that a predominant mechanism for BN film formation is condensation surface recombination of boron ions and neutral atomic nitrogen species. These species arrive nearly simultaneously to the substrate location, and BN formation occurs microseconds before arrival of majority of N+ ions generated by plume collisions with background molecular nitrogen. The energetic nature and extended dwelling time of incident N+ ions at the substrate location was found to negatively impact resulting BN film stoichiometry and thickness. Growth of stoichiometric films was optimized at enriched concentrations of ionized boron and neutral atomic nitrogen in plasma near the condensation surface, providing few nanometer thick films with 1:1 BN stoichiometry and good thicknesses uniformity over macroscopic areas.

  17. Temporally and spatially resolved plasma spectroscopy in pulsed laser deposition of ultra-thin boron nitride films

    SciTech Connect

    Glavin, Nicholas R. E-mail: andrey.voevodin@us.af.mil; Muratore, Christopher; Jespersen, Michael L.; Hu, Jianjun; Fisher, Timothy S.; Voevodin, Andrey A. E-mail: andrey.voevodin@us.af.mil

    2015-04-28

    Physical vapor deposition (PVD) has recently been investigated as a viable, alternative growth technique for two-dimensional materials with multiple benefits over other vapor deposition synthesis methods. The high kinetic energies and chemical reactivities of the condensing species formed from PVD processes can facilitate growth over large areas and at reduced substrate temperatures. In this study, chemistry, kinetic energies, time of flight data, and spatial distributions within a PVD plasma plume ablated from a boron nitride (BN) target by a KrF laser at different pressures of nitrogen gas were investigated. Time resolved spectroscopy and wavelength specific imaging were used to identify and track atomic neutral and ionized species including B{sup +}, B*, N{sup +}, N*, and molecular species including N{sub 2}*, N{sub 2}{sup +}, and BN. Formation and decay of these species formed both from ablation of the target and from interactions with the background gas were investigated and provided insights into fundamental growth mechanisms of continuous, amorphous boron nitride thin films. The correlation of the plasma diagnostic results with film chemical composition and thickness uniformity studies helped to identify that a predominant mechanism for BN film formation is condensation surface recombination of boron ions and neutral atomic nitrogen species. These species arrive nearly simultaneously to the substrate location, and BN formation occurs microseconds before arrival of majority of N{sup +} ions generated by plume collisions with background molecular nitrogen. The energetic nature and extended dwelling time of incident N{sup +} ions at the substrate location was found to negatively impact resulting BN film stoichiometry and thickness. Growth of stoichiometric films was optimized at enriched concentrations of ionized boron and neutral atomic nitrogen in plasma near the condensation surface, providing few nanometer thick films with 1:1 BN stoichiometry and good

  18. Associations between arrhythmia episodes and temporally and spatially resolved black carbon and particulate matter in elderly patients

    PubMed Central

    Zanobetti, Antonella; Coull, Brent A.; Gryparis, Alexandros; Kloog, Itai; Sparrow, David; Vokonas, Pantel S; Wright, Robert O.; Gold, Diane R; Schwartz, Joel

    2015-01-01

    Objectives Ambient air pollution has been associated with sudden deaths, some of which are likely due to ventricular arrhythmias. Defibrillator discharge studies have examined the association of air pollution with arrhythmias in sensitive populations. No studies have assessed this association using residence-specific estimates of air pollution exposure. Methods In the Normative Aging Study, we investigated the association between temporally-and spatially-resolved black carbon (BC) and PM2.5 and arrhythmia episodes (bigeminy, trigeminy or couplets episodes) measured as ventricular ectopy (VE) by 4-min electrocardiogram (ECG) monitoring in repeated measures of 701 subjects, during the years 2000 to 2010. We used a binomial distribution (having or not a VE episode) in a mixed effect model with a random intercept for subject, controlling for seasonality, temperature, day of the week, medication use, smoking, having diabetes, BMI and age. We also examined whether these associations were modified by genotype or phenotype. Results We found significant increases in VE with both pollutants and lags; for the estimated concentration averaged over the three days prior to the health assessment we found increases in the odds of having VE with an OR of 1.52 (95% CI: 1.19–1.94) for an IQR (0.30 μg/m3) increase in BC and an OR of 1.39 (95% CI: 1.12–1.71) for an IQR (5.63 μg/m3) increase in PM2.5. We also found higher effects in subjects with the GSTT1 and GSTM1 variants and in obese (P-values<0.05). Conclusion Increased levels of short-term traffic related pollutants may increase the risk of ventricular arrhythmia in elderly subjects. PMID:24142987

  19. Non-diffusive ignition of a gaseous reactive mixture following time-resolved, spatially distributed energy deposition

    NASA Astrophysics Data System (ADS)

    Kassoy, D. R.

    2014-01-01

    Systematic asymptotic methods are applied to the compressible conservation and state equations for a reactive gas, including transport terms, to develop a rational thermomechanical formulation for the ignition of a chemical reaction following time-resolved, spatially distributed thermal energy addition from an external source into a finite volume of gas. A multi-parameter asymptotic analysis is developed for a wide range of energy deposition levels relative to the initial internal energy in the volume when the heating timescale is short compared to the characteristic acoustic timescale of the volume. Below a quantitatively defined threshold for energy addition, a nearly constant volume heating process occurs, with a small but finite internal gas expansion Mach number. Very little added thermal energy is converted to kinetic energy. The gas expelled from the boundary of the hot, high-pressure spot is the source of mechanical disturbances (acoustic and shock waves) that propagate away into the neighbouring unheated gas. When the energy addition reaches the threshold value, the heating process is fully compressible with a substantial internal gas expansion Mach number, the source of blast waves propagating into the unheated environmental gas. This case corresponds to an extremely large non-dimensional hot-spot temperature and pressure. If the former is sufficiently large, a high activation energy chemical reaction is initiated on the short heating timescale. This phenomenon is in contrast to that for more modest levels of energy addition, where a thermal explosion occurs only after the familiar extended ignition delay period for a classical high activation reaction. Transport effects, modulated by an asymptotically small Knudsen number, are shown to be negligible unless a local gradient in temperature, concentration or velocity is exceptionally large.

  20. Spatially-resolved spectral image of a microwave-induced plasma with Okamoto-cavity for nitridation of steel substrate.

    PubMed

    Sato, Shigeo; Arai, Yuuki; Wagatsuma, Kazuaki

    2014-01-01

    When a nitrogen microwave-induced plasma produced with an Okamoto-cavity was employed as a source for the nitridation of steel samples, the characteristics of the plasma were investigated by analyzing a spatially-resolved emission image of nitrogen excited species obtained with a two-dimensionally imaging spectrograph. Our previous study had reported on an excellent performance of the Okamoto-cavity microwave-induced plasma (MIP), enabling a nitrided layer having a several-micrometer-thickness to form on an iron substrate, even if the treatment is completed within 1 min, which is superior to a conventional plasma nitriding using low-pressure glow discharges requiring a prolonged treatment time. In this paper, the reason for this is discussed based on a spectrometric investigation. The emission images of band heads of nitrogen molecule and nitrogen molecule ion extended toward the axial/radial directions of the plasma at larger microwave powers supplied to the MIP, thus elevating the number density of the excited species of nitrogen, which would activate any chemical reaction on the iron substrate. However, a drastic increase in the growth rate of the nitrided layer when increasing the microwave power from 600 to 700 W, which had been observed in our previous study, could not be explained only from such a variation in the excited species of nitrogen. This result is probably because the growth process is dominantly controlled by thermal diffusion of nitrogen atom after it enters into the iron substrate, where the substrate temperature is the most important parameter concerning the mobility in the iron lattice. Therefore, the Okamoto-cavity MIP could contribute to a thermal source through radiative heating as well as a source of nitrogen excited species, especially in the growth process of the nitrided layer. PMID:24521910

  1. SPATIALLY RESOLVED SPECTROSCOPY AND CHEMICAL HISTORY OF STAR-FORMING GALAXIES IN THE HERCULES CLUSTER: THE EFFECTS OF THE ENVIRONMENT

    SciTech Connect

    Petropoulou, V.; Vilchez, J.; Iglesias-Paramo, J.; Cedres, B.; Papaderos, P.; Magrini, L.; Reverte, D.

    2011-06-10

    Spatially resolved spectroscopy has been obtained for a sample of 27 star-forming (SF) galaxies selected from our deep H{alpha} survey of the Hercules cluster. We have applied spectral synthesis models to all emission-line spectra of this sample using the population synthesis code STARLIGHT and have obtained fundamental parameters of stellar components such as mean metallicity and age. The emission-line spectra were corrected for underlying stellar absorption using these spectral synthesis models. Line fluxes were measured and O/H and N/O gas chemical abundances were obtained using the latest empirical calibrations. We have derived the masses and total luminosities of the galaxies using available Sloan Digital Sky Survey broadband photometry. The effects of cluster environment on the chemical evolution of galaxies and on their mass-metallicity (MZ) and luminosity-metallicity (LZ) relations were studied by combining the derived gas metallicities, the mean stellar metallicities and ages, the masses and luminosities of the galaxies, and their existing H I data. Our Hercules SF galaxies are divided into three main subgroups: (1) chemically evolved spirals with truncated ionized-gas disks and nearly flat oxygen gradients, demonstrating the effect of ram-pressure stripping; (2) chemically evolved dwarfs/irregulars populating the highest local densities, possible products of tidal interactions in preprocessing events; and (3) less metallic dwarf galaxies that appear to be 'newcomers' to the cluster and are experiencing pressure-triggered star formation. Most Hercules SF galaxies follow well-defined MZ and LZ sequences (for both O/H and N/O), though the dwarf/irregular galaxies located at the densest regions appear to be outliers to these global relations, suggesting a physical reason for the dispersion in these fundamental relations. The Hercules cluster appears to be currently assembling via the merger of smaller substructures, providing an ideal laboratory where the

  2. Spatially Resolved Spectroscopy and Chemical History of Star-forming Galaxies in the Hercules Cluster: The Effects of the Environment

    NASA Astrophysics Data System (ADS)

    Petropoulou, V.; Vílchez, J.; Iglesias-Páramo, J.; Papaderos, P.; Magrini, L.; Cedrés, B.; Reverte, D.

    2011-06-01

    Spatially resolved spectroscopy has been obtained for a sample of 27 star-forming (SF) galaxies selected from our deep Hα survey of the Hercules cluster. We have applied spectral synthesis models to all emission-line spectra of this sample using the population synthesis code STARLIGHT and have obtained fundamental parameters of stellar components such as mean metallicity and age. The emission-line spectra were corrected for underlying stellar absorption using these spectral synthesis models. Line fluxes were measured and O/H and N/O gas chemical abundances were obtained using the latest empirical calibrations. We have derived the masses and total luminosities of the galaxies using available Sloan Digital Sky Survey broadband photometry. The effects of cluster environment on the chemical evolution of galaxies and on their mass-metallicity (MZ) and luminosity-metallicity (LZ) relations were studied by combining the derived gas metallicities, the mean stellar metallicities and ages, the masses and luminosities of the galaxies, and their existing H I data. Our Hercules SF galaxies are divided into three main subgroups: (1) chemically evolved spirals with truncated ionized-gas disks and nearly flat oxygen gradients, demonstrating the effect of ram-pressure stripping; (2) chemically evolved dwarfs/irregulars populating the highest local densities, possible products of tidal interactions in preprocessing events; and (3) less metallic dwarf galaxies that appear to be "newcomers" to the cluster and are experiencing pressure-triggered star formation. Most Hercules SF galaxies follow well-defined MZ and LZ sequences (for both O/H and N/O), though the dwarf/irregular galaxies located at the densest regions appear to be outliers to these global relations, suggesting a physical reason for the dispersion in these fundamental relations. The Hercules cluster appears to be currently assembling via the merger of smaller substructures, providing an ideal laboratory where the local

  3. Spatially resolved radio-to-far-infrared SED of the luminous merger remnant NGC 1614 with ALMA and VLA

    NASA Astrophysics Data System (ADS)

    Saito, Toshiki; Iono, Daisuke; Xu, Cong K.; Ueda, Junko; Nakanishi, Kouichiro; Yun, Min S.; Kaneko, Hiroyuki; Yamashita, Takuji; Lee, Minju; Espada, Daniel; Motohara, Kentaro; Kawabe, Ryohei

    2016-04-01

    We present the results of Atacama Large Millimeter/Submillimeter Array (ALMA) 108-, 233-, 352-, and 691-GHz continuum observations and Very Large Array (VLA) 4.81- and 8.36-GHz observations of the nearby luminous merger remnant NGC 1614. By analyzing the beam (1{^''.}0 × 1{^''.}0) and uv (≥45 kλ) matched ALMA and VLA maps, we find that the deconvolved source size of lower-frequency emission (≤108 GHz) is more compact (420 pc × 380 pc) compared to the higher-frequency emission (≥233 GHz) (560 pc × 390 pc), suggesting different physical origins for the continuum emission. Based on a spectral energy distribution (SED) model for a dusty starburst galaxy, it is found that the SED can be explained by three components: (1) non-thermal synchrotron emission (traced in the 4.81- and 8.36-GHz continua), (2) thermal free-free emission (traced in the 108-GHz continuum), and (3) thermal dust emission (traced in the 352- and 691-GHz continua). We also present the spatially resolved (sub-kpc scale) Kennicutt-Schmidt relation of NGC 1614. The result suggests a systematically shorter molecular gas depletion time in NGC 1614 (average τgas of 49-77 Myr and 70-226 Myr at the starburst ring and the outer region, respectively) than that of normal disk galaxies (˜2 Gyr) and a mid-stage merger VV 114 (= 0.1-1 Gyr). This implies that the star formation activities in (ultra-)luminous infrared galaxies are efficiently enhanced as the merger stage proceeds, which is consistent with the results from high-resolution numerical merger simulations.

  4. Analysis of heat-affected zone phase transformations using in situ spatially resolved x-ray diffraction with synchrotron radiation

    SciTech Connect

    Elmer, J.W.; Wong, J.; Froeba, M.; Waide, P.A.; Larson, E.M.

    1996-03-01

    Spatially resolved X-ray diffraction (SRXRD) consists of producing a submillimeter size X-ray beam from an intense synchrotron radiation source to perform real-time diffraction measurements on solid materials. This technique was used int his study to investigate the crystal phases surrounding a liquid weld pool in commercial purity titanium and to determine the location of the phase boundary separating the high-temperature body-centered-cubic (bcc) {beta} phase from the low-temperature hexagonal-close-packed (hcp) {alpha} phase. The experiments were carried out at the Stanford Synchrotron Radiation Laboratory (SSRL) using a 0.25 x 0.50 mm X-ray probe that could be positioned with 10-{micro}m precision on the surface of a quasistationary gas tungsten arc weld (GTAW). The SRXRD results showed characteristic hcp, bcc, and liquid diffraction patterns at various points along the sample, starting from the base metal through the heat-affected zone (HAZ) and into the weld pool, respectively. Analyses of the SRXRD data show the coexistence of bcc and hcp phases in the partially transformed (outer) region of the HAZ and single-phase bcc in the fully transformed (inner) region of the HAZ. Postweld metallographic examinations of the HAZ, combined with a conduction-based thermal model of the weld, were correlated with the SRXRD results. Finally, analysis of the diffraction intensities of the hcp and bcc phases was performed on the SRXRD data to provide additional information about the microstructural conditions that may exist in the HAZ at temperature during welding. This work represents the first direct in situ mapping of phase boundaries in fusion welds.

  5. Influence of cutaneous and muscular circulation on spatially resolved versus standard Beer-Lambert near-infrared spectroscopy.

    PubMed

    Messere, Alessandro; Roatta, Silvestro

    2013-12-01

    The potential interference of cutaneous circulation on muscle blood volume and oxygenation monitoring by near-infrared spectroscopy (NIRS) remains an important limitation of this technique. Spatially resolved spectroscopy (SRS) was reported to minimize the contribution of superficial tissue layers in cerebral monitoring but this characteristic has never been documented in muscle tissue monitoring. This study aims to compare SRS with the standard Beer-Lambert (BL) technique in detecting blood volume changes selectively induced in muscle and skin. In 16 healthy subjects, the biceps brachii was investigated during isometric elbow flexion at 70% of the maximum voluntary contractions lasting 10 sec, performed before and after exposure of the upper arm to warm air flow. From probes applied over the muscle belly the following variables were recorded: total hemoglobin index (THI, SRS-based), total hemoglobin concentration (tHb, BL-based), tissue oxygenation index (TOI, SRS-based), and skin blood flow (SBF), using laser Doppler flowmetry. Blood volume indices exhibited similar changes during muscle contraction but only tHb significantly increased during warming (+5.2 ± 0.7 μmol/L·cm, an effect comparable to the increase occurring in postcontraction hyperemia), accompanying a 10-fold increase in SBF. Contraction-induced changes in tHb and THI were not substantially affected by warming, although the tHb tracing was shifted upward by (5.2 ± 3.5 μmol/L·cm, P < 0.01). TOI was not affected by cutaneous warming. In conclusion, SRS appears to effectively reject interference by SBF in both muscle blood volume and oxygenation monitoring. Instead, BL-based parameters should be interpreted with caution, whenever changes in cutaneous perfusion cannot be excluded. PMID:24744858

  6. Highly spatially resolved structural and optical investigation of Bi nanoparticles in Y-Er disilicate thin films

    NASA Astrophysics Data System (ADS)

    Scarangella, A.; Amiard, G.; Reitano, R.; Priolo, F.; Boninelli, S.; Miritello, M.

    2016-08-01

    Er-containing silicon compatible materials have been widely used as infrared emitters for microphotonics application. In this field, the additional introduction of a proper sensitizer permits to increase the Er excitation cross sections, thus increasing its optical efficiency. This work aims to investigate the influence of a post-transition metal, bismuth, on the optical properties of erbium-yttrium disilicate thin films synthesized by magnetron co-sputtering. After thermal treatments at 1000 °C in O2 or N2 environment, the presence of small precipitates, about 6 nm in diameter, was evidenced by transmission electron microscopy analyses. The spatially resolved chemical nature of the nanoparticles was discerned in the Si and O rich environments by means of scanning transmission electron microscopy-energy dispersive X-ray and scanning transmission electron microscopy-electron energy loss spectroscopy analyses performed with nanometric resolution. In particular, metallic Bi nanoparticles were stabilized in the N2 environment, being strongly detrimental for the Er emission. A different scenario was instead observed in O2, where the formation of Bi silicate nanoparticles was demonstrated with the support of photoluminescence excitation spectroscopy. In particular, a broad band peaked at 255 nm, correlated to the excitation band of Bi silicate nanoparticles, was identified in Er excitation spectrum. Thus Bi silicate clusters act as sensitizer for Er ions, permitting to improve Er emission up to 250 times with respect to the resonant condition. Moreover, the Er decay time increases in the presence of the Bi silicate nanoparticles that act as cages for Er ions. These last results permit to further increase Er optical efficiency in the infrared range, suggesting (Bi + Er)-Y disilicate as a good candidate for applications in microphotonics.

  7. Towards a Novel Spatially-Resolved Hemolysis Detection Method Using a Fluorescent Indicator and Loaded Ghost Cells: Proof-of-Principle.

    PubMed

    Jansen, Sebastian V; Müller, Indra; Kiesendahl, Nicole; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2015-09-01

    It is of the utmost importance to reduce flow-induced hemolysis in devices such as heart-valve prostheses and blood pumps. Thus, in vitro measurements of hemolysis are performed in order to optimize their design in this regard. However, with existing measurement methods, hemolysis can only be assessed as an integrated value over the complete test-circuit. Currently, there are no spatially-resolved in vitro hemolysis measurement techniques known to the authors that would allow for a determination of the critical regions within a device. In this study, a novel spatially-resolved measurement principle is proposed. Ghost cells (i.e. erythrocytes with a lower hemoglobin concentration) were loaded with a calcium-dicitrato complex, and a fluorescent calcium indicator was suspended in the extracellular medium. Calcium and indicator are separated until the cell membrane ruptures (i.e. hemolysis occurs). In the moment of hemolysis, the two compounds bind to each other and emit a fluorescent signal that can be recorded and spatially-resolved in a setup very similar to a standard Particle Image Velocimetry measurement. A proof-of-principle experiment was performed by intentionally inducing hemolysis in a flow-model with a surfactant. The surfactant-induced hemolysis demonstrated a clear increase of the fluorescent signal compared to that of a negative reference. Furthermore, the signal was spatially restricted to the area of hemolysis. Although further challenges need to be addressed, a successful proof-of-principle for novel spatially-resolved hemolysis detection is presented. This method can contribute to better design optimization of devices with respect to flow-induced hemolysis. PMID:26577368

  8. Spatially and temporally resolved electron number density measurements in a decaying laser-induced plasma using hydrogen-alpha line profiles

    NASA Astrophysics Data System (ADS)

    Parigger, Christian; Plemmons, D. H.; Lewis, J. W. L.

    1995-06-01

    A Nd:YAG laser was operated at 1064 nm and with 6-ns pulse duration to achieve optical breakdown in gaseous hydrogen at pressures of 150 and 810 Torr. Spatially and temporally resolved laser-induced emission spectra were measured early in the plasma decay. With hydrogen-alpha line profiles, electron number density values were determined along the laser beam plasma in the range 1019 to 1016 cc -1.

  9. Spatially-resolved chemical analysis of frozen ice cores by cryo-cell-UV-laser-ablation-ICPMS

    NASA Astrophysics Data System (ADS)

    Müller, Wolfgang; Della Lunga, Damiano; Rasmussen, Sune O.; Svensson, Anders

    2015-04-01

    High-latitude ice cores have become the master records of late Pleistocene climate variability. Especially the high-resolution data from Greenland of the past ~125 ka reveal a remarkably changeable glacial climate, and these rapid climate oscillations have been shown to take place within a few years only [1, 2]. The requirement for an improvement in spatial resolution in ice core analysis arises from 1) the continuous thinning of annual layers in deep parts of ice cores to below what is routinely resolvable by continuous flow analysis and 2) the concomitant recrystallization of ice that potentially affects the location of impurities and thus the identification of annual layers. We developed a new technique to analyze elemental concentrations at ppb-levels in frozen ice cores at ~100 um (0.1 mm) resolution, which focuses on seasalt and dust tracers (e.g. Na, Mg, Ca, Al, Fe). It utilizes a custom-built, peltier-cooled cryo-sample holder fully compatible with the two-volume Laurin LA-cell of our RESOlution M-50 excimer (193 nm ArF) LA system, which is coupled to an Agilent 7500cs ICPMS, operated in reaction cell gas mode with H2 to eliminate 40Ar and 40Ar16O to access 40Ca and 56Fe [3]. Using 3 x 5 cm strips of ice cores per sample holder, this setup allows elemental concentrations to be acquired using both depth-profiling along (chains of) spots and/or as continuous lateral profiles, following surface cleaning with a major-element-free ceramic blade. Ice crystal boundaries can be observed with transmitted or reflected light illumination. We focus on NGRIP samples from Greenland Stadial 22 (GS22; ~84-88 ka; ~2695-2720 m) with its corresponding transitions. Owing to analysis in frozen ice, we can easily identify - relative to ice crystal boundaries - the location of cation impurities in both clear ice and so-called cloudy bands that are enriched in impurities. We find a remarkable difference in the location of impurities between these different ice domains [4]. Lower

  10. Magellanic Clues to Spatially-resolved Extinction Corrections for Distant Galaxies in the HST/JWST Era

    NASA Astrophysics Data System (ADS)

    Jansen, Rolf A.; Kim, D.; Shewcraft, T.; Windhorst, R. A.; Tamura, K.

    2014-01-01

    distribution of dust. Resulting predicted β_{V,0} will serve as calibrations for the spatially-resolved extinction correction of galaxies at all redshifts where the method is proved reliable. This work is funded by NASA/ADAP grant NNX12AE47G.

  11. Resolving the shocked gas in HH 54 with Herschel. CO line mapping at high spatial and spectral resolution

    NASA Astrophysics Data System (ADS)

    Bjerkeli, P.; Liseau, R.; Brinch, C.; Olofsson, G.; Santangelo, G.; Cabrit, S.; Benedettini, M.; Black, J. H.; Herczeg, G.; Justtanont, , K.; Kristensen, L. E.; Larsson, B.; Nisini, B.; Tafalla, M.

    2014-11-01

    Context. The HH 54 shock is a Herbig-Haro object, located in the nearby Chamaeleon II cloud. Observed CO line profiles are due to a complex distribution in density, temperature, velocity, and geometry. Aims: Resolving the HH 54 shock wave in the far-infrared (FIR) cooling lines of CO constrain the kinematics, morphology, and physical conditions of the shocked region. Methods: We used the PACS and SPIRE instruments on board the Herschel space observatory to map the full FIR spectrum in a region covering the HH 54 shock wave. Complementary Herschel-HIFI, APEX, and Spitzer data are used in the analysis as well. The observed features in the line profiles are reproduced using a 3D radiative transfer model of a bow-shock, constructed with the Line Modeling Engine code (LIME). Results: The FIR emission is confined to the HH 54 region and a coherent displacement of the location of the emission maximum of CO with increasing J is observed. The peak positions of the high-J CO lines are shifted upstream from the lower J CO lines and coincide with the position of the spectral feature identified previously in CO (10-9) profiles with HIFI. This indicates a hotter molecular component in the upstream gas with distinct dynamics. The coherent displacement with increasing J for CO is consistent with a scenario where IRAS12500 - 7658 is the exciting source of the flow, and the 180 K bow-shock is accompanied by a hot (800 K) molecular component located upstream from the apex of the shock and blueshifted by -7 km s-1. The spatial proximity of this knot to the peaks of the atomic fine-structure emission lines observed with Spitzer and PACS ([O i]63, 145 μm) suggests that it may be associated with the dissociative shock as the jet impacts slower moving gas in the HH 54 bow-shock. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  12. SPATIALLY RESOLVING SUBSTRUCTURES WITHIN THE MASSIVE ENVELOPE AROUND AN INTERMEDIATE-MASS PROTOSTAR: MMS 6/OMC-3

    SciTech Connect

    Takahashi, Satoko; Ho, Paul T. P.; Saigo, Kazuya; Tomida, Kengo

    2012-06-10

    With the Submillimeter Array, the brightest (sub)millimeter continuum source in the Orion Molecular Cloud-2/3 region, MMS 6, has been observed in the 850 {mu}m continuum emission with approximately 10 times better angular resolution than previous studies ( Almost-Equal-To 0.''3, Almost-Equal-To 120 AU at Orion). The deconvolved size, the mass, and the column density of MMS 6-main are estimated to be 0.''32 Multiplication-Sign 0.''29 (132 AU Multiplication-Sign 120 AU), 0.29 M{sub Sun }, and 2.1 Multiplication-Sign 10{sup 25} cm{sup -2}, respectively. The estimated extremely high mean number density, 1.5 Multiplication-Sign 10{sup 10} cm{sup -3}, suggests that MMS 6-main is likely optically thick at 850 {mu}m. We compare our observational data with three theoretical core models: prestellar core, protostellar core + disk-like structure, and first adiabatic core. These comparisons clearly show that the observational data cannot be modeled as a simple prestellar core with a gas temperature of 20 K. A self-luminous source is necessary to explain the observed flux density in the (sub)millimeter wavelengths. Our recent detection of a very compact and energetic outflow in the CO (3-2) and HCN (4-3) lines supports the presence of a protostar. We suggest that MMS 6 is one of the first cases of an intermediate-mass protostellar core at an extremely young stage. In addition to the MMS 6-main peak, we have also spatially resolved a number of spiky structures and sub-clumps, distributed over the central 1000 AU. The masses of these sub-clumps are estimated to be 0.066-0.073 M{sub Sun }, which are on the order of brown dwarf masses. Higher angular resolution and higher sensitivity observations with ALMA and EVLA will reveal the origin and nature of these structures such as whether they are originated from fragmentations, spiral arms, or inhomogeneity within the disk-like structures/envelope.

  13. Development of a modified Respiration Activity Monitoring System for accurate and highly resolved measurement of respiration activity in shake flask fermentations

    PubMed Central

    2012-01-01

    Background The Respiration Activity Monitoring System (RAMOS) is an established device to measure on-line the oxygen transfer rate (OTR), thereby, yielding relevant information about metabolic activities of microorganisms and cells during shake flask fermentations. For very fast-growing microbes, however, the RAMOS technique provides too few data points for the OTR. Thus, this current study presents a new model based evaluation method for generating much more data points to enhance the information content and the precision of OTR measurements. Results In cultivations with E.coli BL21 pRSET eYFP-IL6, short diauxic and even triauxic metabolic activities were detected with much more detail compared to the conventional evaluation method. The decline of the OTR during the stop phases during oxygen limitations, which occur when the inlet and outlet valves of the RAMOS flask were closed for calibrating the oxygen sensor, were also detected. These declines reflected a reduced oxygen transfer due to the stop phases. In contrast to the conventional calculation method the new method was almost independent from the number of stop phases chosen in the experiments. Conclusions This new model based evaluation method unveils new peaks of metabolic activity which otherwise would not have been resolved by the conventional RAMOS evaluation method. The new method yields substantially more OTR data points, thereby, enhancing the information content and the precision of the OTR measurements. Furthermore, oxygen limitations can be detected by a decrease of the OTR during the stop phases. PMID:22901278

  14. A spatially resolving x-ray crystal spectrometer for measurement of ion-temperature and rotation-velocity profiles on the Alcator C-Mod tokamak

    SciTech Connect

    Hill, K. W.; Bitter, M. L.; Scott, S. D.; Ince-Cushman, A.; Reinke, M.; Rice, J. E.; Beiersdorfer, P.; Gu, M.-F.; Lee, S. G.; Broennimann, Ch.; Eikenberry, E. F.

    2008-10-15

    A new spatially resolving x-ray crystal spectrometer capable of measuring continuous spatial profiles of high resolution spectra ({lambda}/d{lambda}>6000) of He-like and H-like Ar K{alpha} lines with good spatial ({approx}1 cm) and temporal ({approx}10 ms) resolutions has been installed on the Alcator C-Mod tokamak. Two spherically bent crystals image the spectra onto four two-dimensional Pilatus II pixel detectors. Tomographic inversion enables inference of local line emissivity, ion temperature (T{sub i}), and toroidal plasma rotation velocity (v{sub {phi}}) from the line Doppler widths and shifts. The data analysis techniques, T{sub i} and v{sub {phi}} profiles, analysis of fusion-neutron background, and predictions of performance on other tokamaks, including ITER, will be presented.

  15. Temporally and spatially resolved photoluminescence investigation of (112{sup ¯}2) semi-polar InGaN/GaN multiple quantum wells grown on nanorod templates

    SciTech Connect

    Liu, B.; Smith, R.; Athanasiou, M.; Yu, X.; Bai, J.; Wang, T.

    2014-12-29

    By means of time-resolved photoluminescence (PL) and confocal PL measurements, temporally and spatially resolved optical properties have been investigated on a number of In{sub x}Ga{sub 1−x}N/GaN multiple-quantum-well (MQW) structures with a wide range of indium content alloys from 13% to 35% on (112{sup ¯}2) semi-polar GaN with high crystal quality, obtained through overgrowth on nanorod templates. With increasing indium content, the radiative recombination lifetime initially increases as expected, but decreases if the indium content further increases to 35%, corresponding to emission in the green spectral region. The reduced radiative recombination lifetime leads to enhanced optical performance for the high indium content MQWs as a result of strong exciton localization, which is different from the behaviour of c-plane InGaN/GaN MQWs, where quantum confined Stark effect plays a dominating role in emission process.

  16. An enhanced droplet-based liquid microjunction surface sampling system coupled with HPLC-ESI-MS/MS for spatially resolved analysis.

    PubMed

    Kertesz, Vilmos; Weiskittel, Taylor M; Van Berkel, Gary J

    2015-03-01

    Droplet-based liquid microjunction surface sampling coupled with high-performance liquid chromatography (HPLC)-electrospray ionization (ESI)-tandem mass spectrometry (MS/MS) for spatially resolved analysis provides the possibility of effective analysis of complex matrix samples and can provide a greater degree of chemical information from a single spot sample than is typically possible with a direct analysis of an extract. Described here is the setup and enhanced capabilities of a discrete droplet liquid microjunction surface sampling system employing a commercially available CTC PAL autosampler. The system enhancements include incorporation of a laser distance sensor enabling unattended analysis of samples and sample locations of dramatically disparate height as well as reliably dispensing just 0.5 μL of extraction solvent to make the liquid junction to the surface, wherein the extraction spot size was confined to an area about 0.7 mm in diameter; software modifications improving the spatial resolution of sampling spot selection from 1.0 to 0.1 mm; use of an open bed tray system to accommodate samples as large as whole-body rat thin tissue sections; and custom sample/solvent holders that shorten sampling time to approximately 1 min per sample. The merit of these new features was demonstrated by spatially resolved sampling, HPLC separation, and mass spectral detection of pharmaceuticals and metabolites from whole-body rat thin tissue sections and razor blade ("crude") cut mouse tissue. PMID:25377777

  17. An enhanced droplet-based liquid microjunction surface sampling system coupled with HPLC-ESI-MS/MS for spatially resolved analysis

    SciTech Connect

    Van Berkel, Gary J.; Weiskittel, Taylor M.; Kertesz, Vilmos

    2014-11-07

    Droplet-based liquid microjunction surface sampling coupled with high-performance liquid chromatography (HPLC)-electrospray ionization (ESI)-tandem mass spectrometry (MS/MS) for spatially resolved analysis provides the possibility of effective analysis of complex matrix samples and can provide a greater degree of chemical information from a single spot sample than is typically possible with a direct analysis of an extract. Described here is the setup and enhanced capabilities of a discrete droplet liquid microjunction surface sampling system employing a commercially available CTC PAL autosampler. The system enhancements include incorporation of a laser distance sensor enabling unattended analysis of samples and sample locations of dramatically disparate height as well as reliably dispensing just 0.5 μL of extraction solvent to make the liquid junction to the surface, wherein the extraction spot size was confined to an area about 0.7 mm in diameter; software modifications improving the spatial resolution of sampling spot selection from 1.0 to 0.1 mm; use of an open bed tray system to accommodate samples as large as whole-body rat thin tissue sections; and custom sample/solvent holders that shorten sampling time to approximately 1 min per sample. Lastly, the merit of these new features was demonstrated by spatially resolved sampling, HPLC separation, and mass spectral detection of pharmaceuticals and metabolites from whole-body rat thin tissue sections and razor blade (“crude”) cut mouse tissue.

  18. An enhanced droplet-based liquid microjunction surface sampling system coupled with HPLC-ESI-MS/MS for spatially resolved analysis

    DOE PAGESBeta

    Van Berkel, Gary J.; Weiskittel, Taylor M.; Kertesz, Vilmos

    2014-11-07

    Droplet-based liquid microjunction surface sampling coupled with high-performance liquid chromatography (HPLC)-electrospray ionization (ESI)-tandem mass spectrometry (MS/MS) for spatially resolved analysis provides the possibility of effective analysis of complex matrix samples and can provide a greater degree of chemical information from a single spot sample than is typically possible with a direct analysis of an extract. Described here is the setup and enhanced capabilities of a discrete droplet liquid microjunction surface sampling system employing a commercially available CTC PAL autosampler. The system enhancements include incorporation of a laser distance sensor enabling unattended analysis of samples and sample locations of dramatically disparatemore » height as well as reliably dispensing just 0.5 μL of extraction solvent to make the liquid junction to the surface, wherein the extraction spot size was confined to an area about 0.7 mm in diameter; software modifications improving the spatial resolution of sampling spot selection from 1.0 to 0.1 mm; use of an open bed tray system to accommodate samples as large as whole-body rat thin tissue sections; and custom sample/solvent holders that shorten sampling time to approximately 1 min per sample. Lastly, the merit of these new features was demonstrated by spatially resolved sampling, HPLC separation, and mass spectral detection of pharmaceuticals and metabolites from whole-body rat thin tissue sections and razor blade (“crude”) cut mouse tissue.« less

  19. The Spatially Resolved Star Formation Law From Integral Field Spectroscopy: VIRUS-P Observations of NGC 5194

    NASA Astrophysics Data System (ADS)

    Blanc, Guillermo A.; Heiderman, Amanda; Gebhardt, Karl; Evans, Neal J., II; Adams, Joshua

    2009-10-01

    We investigate the relation between the star formation rate (SFR) surface density (ΣSFR) and the mass surface density of gas (Σgas) in NGC 5194 (a.k.a. M51a, Whirlpool Galaxy). Visible Integral field Replicable Unit Spectrograph Prototype (VIRUS-P) integral field spectroscopy of the central 4.1 × 4.1 kpc2 of the galaxy is used to measure Hα, Hβ, [O III]λ5007, [N II]λλ6548,6584, and [S II]λλ6717,6731 emission line fluxes for 735 regions ~170 pc in diameter. We use the Balmer decrement to calculate nebular dust extinctions, and correct the observed fluxes in order to accurately measure ΣSFR in each region. Archival H I 21 cm and CO maps with spatial resolution similar to that of VIRUS-P are used to measure the atomic and molecular gas surface density for each region. We present a new method for fitting the star formation law (SFL), which includes the intrinsic scatter in the relation as a free parameter, allows the inclusion of non-detections in both Σgas and ΣSFR, and is free of the systematics involved in performing linear regressions over incomplete data in logarithmic space. After rejecting regions whose nebular spectrum is affected by the central active galactic nucleus in NGC 5194, we use the [S II]/Hα ratio to separate spectroscopically the contribution from the diffuse ionized gas (DIG) in the galaxy, which has a different temperature and ionization state from those of H II regions in the disk. The DIG only accounts for 11% of the total Hα luminosity integrated over the whole central region, but on local scales it can account for up to a 100% of the Hα emission, especially in the inter-arm regions. After removing the DIG contribution from the Hα fluxes, we measure a slope N = 0.82 ± 0.05, and an intrinsic scatter epsilon = 0.43 ± 0.02 dex for the molecular gas SFL. We also measure a typical depletion timescale \\tau =\\Sigma _H\\,{\\mathsc{i}+H_2}/\\Sigma _{SFR} \\approx 2 Gyr, in good agreement with recent measurements by Bigiel et al. The

  20. Spatially resolved X-ray emission measurements of the residual velocity during the stagnation phase of inertial confinement fusion implosion experiments

    NASA Astrophysics Data System (ADS)

    Ruby, J. J.; Pak, A.; Field, J. E.; Ma, T.; Spears, B. K.; Benedetti, L. R.; Bradley, D. K.; Berzak Hopkins, L. F.; Casey, D. T.; Döppner, T.; Eder, D.; Fittinghoff, D.; Grim, G.; Hatarik, R.; Hinkel, D. E.; Izumi, N.; Kilkenny, J. D.; Khan, S. F.; Knauer, J. P.; Kritcher, A. L.; Merrill, F. E.; Moody, J. D.; Nagel, S. R.; Park, H.-S.; Salmonson, J. D.; Sayre, D. B.; Callahan, D. A.; Hsing, W. W.; Hurricane, O. A.; Patel, P. K.; Edwards, M. J.

    2016-07-01

    A technique for measuring residual motion during the stagnation phase of an indirectly driven inertial confinement experiment has been implemented. This method infers a velocity from spatially and temporally resolved images of the X-ray emission from two orthogonal lines of sight. This work investigates the accuracy of recovering spatially resolved velocities from the X-ray emission data. A detailed analytical and numerical modeling of the X-ray emission measurement shows that the accuracy of this method increases as the displacement that results from a residual velocity increase. For the typical experimental configuration, signal-to-noise ratios, and duration of X-ray emission, it is estimated that the fractional error in the inferred velocity rises above 50% as the velocity of emission falls below 24 μm/ns. By inputting measured parameters into this model, error estimates of the residual velocity as inferred from the X-ray emission measurements are now able to be generated for experimental data. Details of this analysis are presented for an implosion experiment conducted with an unintentional radiation flux asymmetry. The analysis shows a bright localized region of emission that moves through the larger emitting volume at a relatively higher velocity towards the location of the imposed flux deficit. This technique allows for the possibility of spatially resolving velocity flows within the so-called central hot spot of an implosion. This information would help to refine our interpretation of the thermal temperature inferred from the neutron time of flight detectors and the effect of localized hydrodynamic instabilities during the stagnation phase. Across several experiments, along a single line of sight, the average difference in magnitude and direction of the measured residual velocity as inferred from the X-ray and neutron time of flight detectors was found to be ˜13 μm/ns and ˜14°, respectively.

  1. Compact all-fiber quartz-enhanced photoacoustic spectroscopy sensor with a 30.72 kHz quartz tuning fork and spatially resolved trace gas detection

    NASA Astrophysics Data System (ADS)

    Ma, Yufei; He, Ying; Yu, Xin; Zhang, Jingbo; Sun, Rui; Tittel, Frank K.

    2016-02-01

    An ultra compact all-fiber quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor using quartz tuning fork (QTF) with a low resonance frequency of 30.72 kHz was demonstrated. Such a sensor architecture has the advantages of easier optical alignment, lower insertion loss, lower cost, and more compact compared with a conventional QEPAS sensor using discrete optical components for laser delivery and coupling to the QTF. A fiber beam splitter and three QTFs were employed to perform multi-point detection and demonstrated the potential of spatially resolved measurements.

  2. Development of a Spatially Resolving X-Ray Crystal Spectrometer (XCS) for Measurement of Ion-Temperature (Ti) and Rotation-Velocity (v) Profiles in ITER

    SciTech Connect

    Hill, K W; Delgado-Aprico, L; Johnson, D; Feder, R; Beiersdorfer,; Dunn, J; Morris, K; Wang, E; Reinke, M; Podpaly, Y; Rice, J E; Barnsley, R; O'Mullane, M; Lee, S G

    2010-05-21

    Imaging XCS arrays are being developed as a US-ITER activity for Doppler measurement of Ti and v profiles of impurities (W, Kr, Fe) with ~7 cm (a/30) and 10-100 ms resolution in ITER. The imaging XCS, modeled after a PPPL-MIT instrument on Alcator C-Mod, uses a spherically bent crystal and 2d x-ray detectors to achieve high spectral resolving power (E/dE>6000) horizontally and spatial imaging vertically. Two arrays will measure Ti and both poloidal and toroidal rotation velocity profiles. Measurement of many spatial chords permits tomographic inversion for inference of local parameters. The instrument design, predictions of performance, and results from C-Mod will be presented.

  3. Development Of a Spatially Resolving X-ray Crystal Spectrometer For Measurement Of Ion-temperature (Ti) And Rotation-velocity (v) Profiles in ITER

    SciTech Connect

    Hill, K W; Delgado-Aparico, L; Johnson, David; Feder, R; Beiersdorfer, P; Dunn, James; Morris, K; Wang, E; Reinke, M; Podpaly, Y; Rice, J E; Barnsley, R; O'Mullane, M

    2010-12-15

    Imaging x-ray crystal spectrometer XCS arrays are being developed as a US-ITER activity for Doppler measurement of Ti and v profiles of impurities (W, Kr, and Fe) with ~ 7 cm (a/30) and 10-100 ms resolution in ITER. The imaging XCS, modeled after a prototype instrument on Alcator C-Mod, uses a spherically bent crystal and 2D x-ray detectors to achieve high spectral resolving power (E / dE > 6000) horizontally and spatial imaging vertically. Two arrays will measure Ti and both poloidal and toroidal rotation velocity profiles. The measurement of many spatial chords permits tomographic inversion for the inference of local parameters. The instrument design, predictions of performance, and results from C-Mod are presented.

  4. Development of a spatially resolving x-ray crystal spectrometer for measurement of ion-temperature (T{sub i}) and rotation-velocity (v) profiles in ITER

    SciTech Connect

    Hill, K. W.; Bitter, M.; Delgado-Aparicio, L.; Johnson, D.; Feder, R.; Beiersdorfer, P.; Dunn, J.; Morris, K.; Wang, E.; Reinke, M.; Podpaly, Y.; Rice, J. E.; Barnsley, R.; O'Mullane, M.; Lee, S. G.

    2010-10-15

    Imaging x-ray crystal spectrometer (XCS) arrays are being developed as a US-ITER activity for Doppler measurement of T{sub i} and v profiles of impurities (W, Kr, and Fe) with {approx}7 cm (a/30) and 10-100 ms resolution in ITER. The imaging XCS, modeled after a prototype instrument on Alcator C-Mod, uses a spherically bent crystal and 2D x-ray detectors to achieve high spectral resolving power (E/dE>6000) horizontally and spatial imaging vertically. Two arrays will measure T{sub i} and both poloidal and toroidal rotation velocity profiles. The measurement of many spatial chords permits tomographic inversion for the inference of local parameters. The instrument design, predictions of performance, and results from C-Mod are presented.

  5. Spatially Resolved Observation of Static Magnetic Flux States in YBa_2Cu_3O7-δ Grain Boundary Josephson Junctions

    NASA Astrophysics Data System (ADS)

    Fischer, G. M.; Mayer, B.; Gross, R.; Nissel, T.; Husemann, K.-D.; Huebener, R. P.; Freltoft, T.; Shen, Y.; Vase, P.

    1994-02-01

    With low-temperature scanning electron microscopy, the magnetic flux states in high critical temperature Josephson junctions have been imaged. The experiments were performed with YBa_2Cu_3O7-δ thin-film grain boundary Josephson junctions fabricated on [001] tilt SrTiO_3 bicrystals. For applied magnetic fields parallel to the grain boundary plane, which correspond to local maxima of the magnetic field dependence of the critical current, the images clearly show the corresponding magnetic flux states in the grain boundary junction. The spatial modulation of the Josephson current density by the external magnetic field is imaged directly with a spatial resolution of about 1 micrometer.

  6. Tunable Reflective Spatial Heterodyne Spectrometer: A Technique for High Resolving Power, Wide Field Of View Observation Of Diffuse Emission Line Sources

    NASA Astrophysics Data System (ADS)

    Hosseini, Seyedeh Sona

    The purpose of this dissertation is to discuss the need for new technology in broadband high-resolution spectroscopy based on the emerging technique of Spatial Heterodyne Spectroscopy (SHS) and to propose new solutions that should enhance and generalize this technology to other fields. Spectroscopy is a proven tool for determining compositional and other properties of remote objects. Narrow band imaging and low resolving spectroscopic measurements provide information about composition, photochemical evolution, energy distribution and density. The extension to high resolving power provides further access to temperature, velocity, isotopic ratios, separation of blended sources, and opacity effects. In current high resolving power devices, the drawback of high-resolution spectroscopy is bound to the instrumental limitations of lower throughput, the necessity of small entrance apertures, sensitivity, field of view, and large physical instrumental size. These limitations quickly become handicapping for observation of faint and/or extended targets and for spacecraft encounters. A technique with promise for the study of faint and extended sources at high resolving power is the reflective format of the Spatial Heterodyne Spectrometer (SHS). SHS instruments are compact and naturally tailored for both high etendue (defined in section 2.2.5) and high resolving power. In contrast, to achieve similar spectral grasp, grating spectrometers require large telescopes. For reference, SHS is a cyclical interferometer that produces Fizeau fringe pattern for all other wavelengths except the tuned wavelength. The large etendue obtained by SHS instruments makes them ideal for observations of extended, low surface brightness, isolated emission line sources, while their intrinsically high spectral resolution enables one to study the dynamical and physical properties described above. This document contains four chapters. Chapter 1, introduces a class of scientific targets that formerly have

  7. Continuous Flow Liquid Microjunction Surface Sampling Probe Connected On-line with HPLC/MS for Spatially Resolved Analysis of Small Molecules and Proteins

    SciTech Connect

    Van Berkel, Gary J; Kertesz, Vilmos

    2013-01-01

    RATIONALE: A continuous flow liquid microjunction surface sampling probe extracts soluble material from surfaces for direct ionization and detection by MS. Demonstrated here is the on-line coupling of such a probe with HPLC/MS enabling extraction, separation and detection of small molecules and proteins from surfaces in a spatially resolved (~0.5 mm diameter spots) manner. Methods: A continuous flow liquid microjunction surface sampling probe was connected to a 6-port, 2-position valve for extract collection and injection to an HPLC column. A QTRAP 5500 hybrid triple quadrupole linear ion trap equipped with a Turbo V ion source operated in positive ESI mode was used for all experiments. System operation was tested with extraction, separation and detection of propranolol and associated metabolites from drug dosed tissues and proteins from dried sheep blood spots on paper. Results: Confirmed in the tissue were the parent drug and two different hydroxypropranolol glucuronides. The mass spectrometric response for these compounds from different locations in the liver showed an increase with increasing extraction time (5, 20 and 40 s extractions). For on-line separation and detection/identification of extracted proteins from dried sheep blood spots, two major protein peaks dominated the chromatogram and could be correlated with the expected masses for the hemoglobin and chains. Conclusions: Spatially resolved sampling, separation, and detection of small molecules and proteins from surfaces can be accomplished using a continuous flow liquid microjunction surface sampling probe coupled on-line with HPLC/MS detection.

  8. Performance and Prospects of Khayyam, A Tunable Spatial Heterodyne Spectrometer (SHS) for High Spectral Resolving Power Observation of Extended Planetary Targets in Optical Wavelengths

    NASA Astrophysics Data System (ADS)

    Hosseini, S.; Harris, W.

    2014-12-01

    We present initial results, calibration and data reduction process from observations of wide-field targets using Khayyam at Mt. Hamilton, a new instrument based on a reflective spatial heterodyne spectrometer (SHS) at the focus of the Coudé Auxiliary Telescope (CAT). SHS instruments are common path two-beam Fourier transform spectrometers that produce 2-D spatial interference patterns without the requirement for moving parts. The utility of SHS comes from its combination of a wide input acceptance angle (0.5-1°), high resolving power (of order ~105), compact format, high dynamic range, and relaxed optical tolerances compared with other interferometer designs. This combination makes them extremely useful for velocity resolved for observations of wide field targets from both small and large telescopes. This report focuses on the tunable instrument at Mt Hamilton, The CAT provides a test case for on-axis use of SHS, and the impact of the resulting field non-uniformity caused by the spider pattern will be discussed. Observations of several targets will be presented that demonstrate the capabilities of SHS, including comet C/2014 E2 (Jacques), Jupiter, and both the day sky and night glow. Raw interferometric data and transformed power spectra will be shown and evaluated in terms of instrumental stability.

  9. Methods and apparatus of spatially resolved electroluminescence of operating organic light-emitting diodes using conductive atomic force microscopy

    NASA Technical Reports Server (NTRS)

    Hersam, Mark C. (Inventor); Pingree, Liam S. C. (Inventor)

    2008-01-01

    A conductive atomic force microscopy (cAFM) technique which can concurrently monitor topography, charge transport, and electroluminescence with nanometer spatial resolution. This cAFM approach is particularly well suited for probing the electroluminescent response characteristics of operating organic light-emitting diodes (OLEDs) over short length scales.

  10. Multidimensional spectroscopic data fusion improves precancerous tissue discrimination based on spatially resolved autofluorescence and diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Abdat, F.; Amouroux, M.; Guermeur, Y.; Blondel, W.

    2015-07-01

    The current study deals with new perspectives to perform more efficient classification of mouse skin precancerous stages by means of a decision fusion scheme based on belief functions and exploiting the spatial resolution of the autofluorescence and diffuse reflectance spectroscopic data.

  11. Studies of mechanisms of decay and recovery in organic dye-doped polymers using spatially resolved white light interferometry

    NASA Astrophysics Data System (ADS)

    Anderson, Benjamin; Bernhardt, Elizabeth; Kuzyk, Mark

    2012-10-01

    Several organic dyes have been shown to self heal when doped in a polymer matrix. Most measurements to date use optical absorbance, amplified spontaneous emission, or digital imaging as a probe. Each method determines a subset of the relevant parameters. We have constructed a white light interferometric microscope, which measures the absorption spectrum and change in refractive index during decay and recovery simultaneously at multiple points in the material. We report on preliminary measurements and results concerning the microscopes spatial resolution.

  12. Development of a Schottky CdTe Medipix3RX hybrid photon counting detector with spatial and energy resolving capabilities

    NASA Astrophysics Data System (ADS)

    Gimenez, E. N.; Astromskas, V.; Horswell, I.; Omar, D.; Spiers, J.; Tartoni, N.

    2016-07-01

    A multichip CdTe-Medipix3RX detector system was developed in order to bring the advantages of photon-counting detectors to applications in the hard X-ray range of energies. The detector head consisted of 2×2 Medipix3RX ASICs bump-bonded to a 28 mm×28 mm e- collection Schottky contact CdTe sensor. Schottky CdTe sensors undergo performance degrading polarization which increases with temperature, flux and the longer the HV is applied. Keeping the temperature stable and periodically refreshing the high voltage bias supply was used to minimize the polarization and achieve a stable and reproducible detector response. This leads to good quality images and successful results on the energy resolving capabilities of the system.

  13. TU-F-17A-04: Respiratory Phase-Resolved 3D MRI with Isotropic High Spatial Resolution: Determination of the Average Breathing Motion Pattern for Abdominal Radiotherapy Planning

    SciTech Connect

    Deng, Z; Pang, J; Yang, W; Yue, Y; Tuli, R; Fraass, B; Li, D; Fan, Z

    2014-06-15

    Purpose: To develop a retrospective 4D-MRI technique (respiratory phase-resolved 3D-MRI) for providing an accurate assessment of tumor motion secondary to respiration. Methods: A 3D projection reconstruction (PR) sequence with self-gating (SG) was developed for 4D-MRI on a 3.0T MRI scanner. The respiration-induced shift of the imaging target was recorded by SG signals acquired in the superior-inferior direction every 15 radial projections (i.e. temporal resolution 98 ms). A total of 73000 radial projections obtained in 8-min were retrospectively sorted into 10 time-domain evenly distributed respiratory phases based on the SG information. Ten 3D image sets were then reconstructed offline. The technique was validated on a motion phantom (gadolinium-doped water-filled box, frequency of 10 and 18 cycles/min) and humans (4 healthy and 2 patients with liver tumors). Imaging protocol included 8-min 4D-MRI followed by 1-min 2D-realtime (498 ms/frame) MRI as a reference. Results: The multiphase 3D image sets with isotropic high spatial resolution (1.56 mm) permits flexible image reformatting and visualization. No intra-phase motion-induced blurring was observed. Comparing to 2D-realtime, 4D-MRI yielded similar motion range (phantom: 10.46 vs. 11.27 mm; healthy subject: 25.20 vs. 17.9 mm; patient: 11.38 vs. 9.30 mm), reasonable displacement difference averaged over the 10 phases (0.74mm; 3.63mm; 1.65mm), and excellent cross-correlation (0.98; 0.96; 0.94) between the two displacement series. Conclusion: Our preliminary study has demonstrated that the 4D-MRI technique can provide high-quality respiratory phase-resolved 3D images that feature: a) isotropic high spatial resolution, b) a fixed scan time of 8 minutes, c) an accurate estimate of average motion pattern, and d) minimal intra-phase motion artifact. This approach has the potential to become a viable alternative solution to assess the impact of breathing on tumor motion and determine appropriate treatment margins

  14. Resolving the spatial variability of sediment geochemistry within a seagrass (Zostera marina) meadow in the coastal bays of Virginia

    NASA Astrophysics Data System (ADS)

    Egge, N. E.; Macko, S. A.; O'connell, M. T.

    2013-12-01

    The environmental degradation of the areas of coastal Chesapeake Bay has been linked with explosive urbanization associated with human population growth and dramatic increases in agricultural activities. Possible impacts of these have been associated with diminishing seagrass (Zostera marina) coverage. Numerous efforts have been made to restore seagrass meadows. As a result of large-scale, seed-based restorations in South Bay (2001) and Hog Island Bay (2007), Z. marina has come to dominate portions of these bays. In this study, a spatially random sampling pattern was used to assess the frequency at which a variety of geochemical characteristics within the South Bay study area were correlated. Initial sampling is within a hectare window; cores were collected in a plot of samples simulated as a homogeneous Poisson distribution. Stable isotope and geochemical proxies are used to suggest the source of organic material within the coastal bays. Carbon and nitrogen isotope analyses were conducted on freeze-dried and acidified samples; sediments dominated by seagrass contain organic matter more enriched in 13C relative to autochthonous algal and planktonic marine materials. These data have been used to establish the spatial autocorrelation of sediment geochemistry for the surface, as well as deeper sediments. After the initial geostatistical parameter estimation, a random systematic grid pattern has been applied that satisfies assumptions of non-preferential design by randomly locating sampling points within the grid space. The systematic grid thus allows for the representation of the plot as a whole, as well as evaluation of spatial trends within the data. Fitting of geostatistical models will be presented using both conventional and Bayesian Kriging models. Results from this study may be able to be used to evaluate potential for carbon sequestration in these system as well as guide future restoration projects.

  15. A fiber optic probe to measure spatially resolved diffuse reflectance in the sub-diffusion regime for in-vivo use (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Eshein, Adam; Wu, Wenli; Nguyen, The-Quyen; Radosevich, Andrew J.; Backman, Vadim

    2016-03-01

    We present an ultra-simple miniature fiber optic probe to measure spatially and spectrally resolved diffuse reflectance in the sub-diffuse regime (i.e. measurements with source-detector separation less than a transport mean free path) in-vivo. This probe has a robust and simple design with a small footprint (<.5 mm diameter). We show that our probe has sensitivity to structures scattering light an order of magnitude smaller than the diffraction limit, and thus can be used to quantify alterations in the very smallest structures in tissue (e.g. organelles, chromatin, collagen fibers, etc.). Specifically, the probe samples the spatial profile of diffuse reflectance in the sub-diffusion regime (P(r), r<<1 mm). P(r) can be used to quantify the entire shape of the phase function, F(θ). The shape of the refractive index correlation function Bn(rd) (through which the spatial distribution of mass is defined) can be analytically derived from the shape of F(θ) through application of the Born approximation. Therefor measurements of P(r) can elucidate F(θ) and Bn(rd). This ability has tremendous potential for use as a diagnostic tool and broad applications for probing the nanoscale environment of tissue in-vivo.

  16. An Assessment of the Ability of Potential Satellite Instruments to Resolve Spatial and Temporal Variability of Atmospheric CO2

    NASA Technical Reports Server (NTRS)

    Andrews, A.; Bhartia, Pawan (Technical Monitor)

    2002-01-01

    Sufficiently precise satellite observations with adequate spatial and temporal resolution would substantially increase our knowledge of the atmospheric CO2 distribution and would undoubtedly lead to reduced uncertainty in estimates of the global carbon budget. An overview of possible strategies for measuring CO2 from space will be presented, including IR and nearby measurements, active sensors and broad band and narrow band passive sensors. The ability of potential satellite instruments with a variety of orbits, horizontal resolution and vertical weighting functions to capture the variation in atmospheric CO2 mixing ratios will be illustrated using a combination of surface data, aircraft data and model results.

  17. Spatially resolved analysis of small molecules by matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI).

    PubMed

    Peukert, Manuela; Matros, Andrea; Lattanzio, Giuseppe; Kaspar, Stephanie; Abadía, Javier; Mock, Hans-Peter

    2012-02-01

    • Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) of tissues provides the means to analyse the spatial distributions of small molecules and proteins within tissues. This imaging technique is commonplace in medicinal and pharmaceutical research, but its application in plant science is very recent. Broader introduction requires specific adaptations for plant tissues. Sample preparation is of paramount importance in order to obtain high-quality spectra providing sufficient spatial resolution for compounds. Optimization is required for sectioning, choice of matrix and means of matrix deposition. • Here, we present our current protocols for the detection of small molecules in cryodissected immature barley (Hordeum vulgare) grains and tobacco (Nicotiana tabacum) roots. • Examples of MALDI-MSI measurements are provided, and the level of reproducibility across biological replicates is addressed. Furthermore, our approaches for the validation of distribution patterns and for the identification of molecules are described. • Finally, we discuss how MALDI-MSI can contribute to applied plant research. PMID:22126099

  18. A spatially resolved retarding field energy analyzer design suitable for uniformity analysis across the surface of a semiconductor wafer

    SciTech Connect

    Sharma, S.; Gahan, D. Hopkins, M. B.; Kechkar, S.; Daniels, S.

    2014-04-15

    A novel retarding field energy analyzer design capable of measuring the spatial uniformity of the ion energy and ion flux across the surface of a semiconductor wafer is presented. The design consists of 13 individual, compact-sized, analyzers, all of which are multiplexed and controlled by a single acquisition unit. The analyzers were tested to have less than 2% variability from unit to unit due to tight manufacturing tolerances. The main sensor assembly consists of a 300 mm disk to mimic a semiconductor wafer and the plasma sampling orifices of each sensor are flush with disk surface. This device is placed directly on top of the rf biased electrode, at the wafer location, in an industrial capacitively coupled plasma reactor without the need for any modification to the electrode structure. The ion energy distribution, average ion energy, and average ion flux were measured at the 13 locations over the surface of the powered electrode to determine the degree of spatial nonuniformity. The ion energy and ion flux are shown to vary by approximately 20% and 5%, respectively, across the surface of the electrode for the range of conditions investigated in this study.

  19. A spatially resolved retarding field energy analyzer design suitable for uniformity analysis across the surface of a semiconductor wafer.

    PubMed

    Sharma, S; Gahan, D; Kechkar, S; Daniels, S; Hopkins, M B

    2014-04-01

    A novel retarding field energy analyzer design capable of measuring the spatial uniformity of the ion energy and ion flux across the surface of a semiconductor wafer is presented. The design consists of 13 individual, compact-sized, analyzers, all of which are multiplexed and controlled by a single acquisition unit. The analyzers were tested to have less than 2% variability from unit to unit due to tight manufacturing tolerances. The main sensor assembly consists of a 300 mm disk to mimic a semiconductor wafer and the plasma sampling orifices of each sensor are flush with disk surface. This device is placed directly on top of the rf biased electrode, at the wafer location, in an industrial capacitively coupled plasma reactor without the need for any modification to the electrode structure. The ion energy distribution, average ion energy, and average ion flux were measured at the 13 locations over the surface of the powered electrode to determine the degree of spatial nonuniformity. The ion energy and ion flux are shown to vary by approximately 20% and 5%, respectively, across the surface of the electrode for the range of conditions investigated in this study. PMID:24784609

  20. Fast, spatially resolved thermometry of Si and GaP crystals using pump-probe two-photon absorption

    NASA Astrophysics Data System (ADS)

    Min, Chang-Ki; Park, Ji Yong; Cahill, David G.; Granick, Steve

    2009-07-01

    Noncontact thermometry with micron-scale lateral spatial resolution and fast time resolution is shown to be enabled by measuring the temperature dependence of two-photon absorption (TPA) on crystalline semiconductors. In the proof-of-concept experiments reported here, for studies of Si, an Er:fiber laser at λ =1.56 μm is split into pump and probe beams; where they overlap, the large TPA signal changes strongly with temperature because the two-photon energy lies between the indirect and direct bandgaps of Si. We show that the TPA coefficient increases by a factor of 2 when the temperature increases from 30 to 300 °C. For studies of GaP, we use instead a Ti:sapphire laser at 790 nm to achieve two-photon excitation above the direct bandgap. In GaP, contributions to the TPA from the dominant direct transition show less temperature dependence than for Si but the additional contribution of the indirect transition gives a similar magnitude as the temperature dependence of TPA on Si. In the current implementation using Si, the spatial resolution of the thermometry is 6×6×50 μm3 and the sensitivity is 0.6 K in a 1 kHz bandwidth.

  1. Spatially Resolved Energetic Electron Properties for the 21 May 2004 Flare from Radio Observations and 3D Simulations

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. A.; Kontar, E. P.

    2015-01-01

    We investigated in detail the 21 May 2004 flare using simultaneous observations of the Nobeyama Radioheliograph, the Nobeyama Radiopolarimeters, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and the Solar and Heliospheric Observatory (SOHO). The flare images in different spectral ranges reveal a well-defined single flaring loop in this event. We simulated the gyrosynchrotron microwave emission using the recently developed interactive IDL tool GX Simulator. By comparing the simulation results with the observations, we deduced the spatial and spectral properties of the non-thermal electron distribution. The microwave emission has been found to be produced by the high-energy electrons (> 100 keV) with a relatively hard spectrum ( δ≃2); the electrons were strongly concentrated near the loop top. At the same time, the number of high-energy electrons near the footpoints was too low to be detected in the RHESSI images and spatially unresolved data. The SOHO Extreme-ultraviolet Imaging Telescope images and the low-frequency microwave spectra suggest the presence of an extended "envelope" of the loop with lower magnetic field. Most likely, the energetic electron distribution in the considered flare reflects the localized (near the loop top) particle acceleration (injection) process accompanied by trapping and scattering.

  2. Tempo-spatially resolved dynamics of elec- trons and holes in bilayer MoS2 -WS2

    NASA Astrophysics Data System (ADS)

    Galicia-Hernandez, J. M.; Turkowski, V.; Hernandez-Cocoletzi, G.; Rahman, T. S.

    We have performed a Density-Matrix Time-Dependent Density-Functional Theory analysis of the response of bilayer MoS2-WS2 to external laser-pulse perturbations. Time-resolved study of the dynamics of electrons and holes, including formation and dissociation of strongly-bound intra- and inter-layer excitonic states, shows that the experimentally observed ultrafast inter-layer MoS2 to WS2 migration of holes may be attributed to unusually large delocalization of the hole state which extends far into the inter-layer region. We also argue that the velocity of the hole transfer may be further enhanced by its interaction with transfer phonon modes. We analyze other possible consequences of the hole delocalization in the system, including reduction of the effects of the electron-electron and hole-hole repulsion in the trions and biexcitons as compared to that in the monolayers Work supported in part by DOE Grant No. DOE-DE-FG02-07ER46354 and by CONACYT Scholarship No. 23210 (J.M.G.H.).

  3. Growth and development of the barnacle Amphibalanus amphitrite: time and spatially resolved structure and chemistry of the base plate

    PubMed Central

    Burden, Daniel K.; Spillmann, Christopher M.; Everett, Richard K.; Barlow, Daniel E.; Orihuela, Beatriz; Deschamps, Jeffrey R.; Fears, Kenan P.; Rittschof, Daniel; Wahl, Kathryn J.

    2014-01-01

    The radial growth and advancement of the adhesive interface to the substratum of many species of acorn barnacles occurs underwater and beneath an opaque, calcified shell. Here, the time-dependent growth processes involving various autofluorescent materials within the interface of live barnacles are imaged for the first time using 3D time-lapse confocal microscopy. Key features of the interface development in the striped barnacle, Amphibalanus (= Balanus) amphitrite were resolved in situ and include advancement of the barnacle/substratum interface, epicuticle membrane development, protein secretion, and calcification. Microscopic and spectroscopic techniques provide ex situ material identification of regions imaged by confocal microscopy. In situ and ex situ analysis of the interface support the hypothesis that barnacle interface development is a complex process coupling sequential, timed secretory events and morphological changes. This results in a multi-layered interface that concomitantly fulfills the roles of strongly adhering to a substratum while permitting continuous molting and radial growth at the periphery. PMID:25115515

  4. Invited Article: Micron resolution spatially resolved measurement of heat capacity using dual-frequency time-domain thermoreflectance

    NASA Astrophysics Data System (ADS)

    Wei, Changdong; Zheng, Xuan; Cahill, David G.; Zhao, Ji-Cheng

    2013-07-01

    A pump-probe photothermal technique - dual-frequency time-domain thermoreflectance - was developed for measuring heat capacity with a spatial resolution on the order of 10 μm. The method was validated by measuring several common materials with known heat capacity. Rapid measurement of composition-phase-property relationships was demonstrated on Ti-TiSi2 and Ni-Zr diffusion couples; experimental values of heat capacity of the intermetallic compounds in these diffusion couples were compared with literature values and CALPHAD (CALculation of PHAse Diagram) calculations. The combination of this method and diffusion multiples provides an efficient way to generate thermodynamic data for CALPHAD modeling and database construction. The limitation of this method in measuring low thermal diffusivity materials is also discussed.

  5. Implications for gravitational lensing and the dark matter content in clusters of galaxies from spatially resolved x-ray spectra

    NASA Technical Reports Server (NTRS)

    Loewenstein, M.

    1994-01-01

    A simple method for deriving well-behaved temperature solutions to the equation of hydrostatic equilibrium for intracluster media with X-ray imaging observations is presented and applied to a series of generalized models as well as to observations of the Perseus cluster and Abell 2256. In these applications the allowed range in the ratio of nonbaryons to baryons as a function of radius is derived, taking into account the uncertainties and crude spatial resolution of the X-ray spectra and considering a range of physically reasonable mass models with various scale heights. Particular attention is paid to the central regions of the cluster, and it is found that the dark matter can be sufficiently concentrated to be consistent with the high central mass surface densities for moderate-redshift clusters from their gravitational lensing properties.

  6. Invited article: micron resolution spatially resolved measurement of heat capacity using dual-frequency time-domain thermoreflectance.

    PubMed

    Wei, Changdong; Zheng, Xuan; Cahill, David G; Zhao, Ji-Cheng

    2013-07-01

    A pump-probe photothermal technique - dual-frequency time-domain thermoreflectance - was developed for measuring heat capacity with a spatial resolution on the order of 10 μm. The method was validated by measuring several common materials with known heat capacity. Rapid measurement of composition-phase-property relationships was demonstrated on Ti-TiSi2 and Ni-Zr diffusion couples; experimental values of heat capacity of the intermetallic compounds in these diffusion couples were compared with literature values and CALPHAD (CALculation of PHAse Diagram) calculations. The combination of this method and diffusion multiples provides an efficient way to generate thermodynamic data for CALPHAD modeling and database construction. The limitation of this method in measuring low thermal diffusivity materials is also discussed. PMID:23902037

  7. Spatially resolved photoconductivity of thin films formed by colloidal octapod-shaped CdSe/CdS nanocrystals.

    PubMed

    Zhang, Yang; Miszta, Karol; Kudera, Stefan; Manna, Liberato; Di Fabrizio, Enzo; Krahne, Roman

    2011-07-01

    We studied the optical absorption and photoconductive properties of thin films consisting of core-shell octapod-shaped nanocrystals, which consisted of CdS pods that branch out from a CdSe core. The current-voltage characteristics were measured at room and cryogenic temperatures and agreed well with a phenomenological exponential fitting model, from which we could extract the sheet resistance and the average voltage barrier for the charge tunneling between the octapods. The temperature dependence of the photocurrent showed temperature activated behavior above 220 K and a non-Arrhenius exponential (T/T(0))(n) dispersion below 220 K. Furthermore, we mapped the photocurrent generation within the octapod film via scanning photocurrent microscopy, which revealed photocurrent enhancement near micron-size voids and spatial shifts of the photocurrent maxima with bias voltage. PMID:21643586

  8. Spectral and spatial resolving of photoelectric property of femtosecond laser drilled holes of GaSb(1-x)Bi(x).

    PubMed

    Pan, C B; Zha, F X; Song, Y X; Shao, J; Dai, Y; Chen, X R; Ye, J Y; Wang, S M

    2015-07-15

    Femtosecond laser drilled holes of GaSbBi were characterized by the joint measurements of photoconductivity (PC) spectroscopy and laser-beam-induced current (LBIC) mapping. The excitation light in PC was focused down to 60 μm presenting the spectral information of local electronic property of individual holes. A redshift of energy band edge of about 6-8 meV was observed by the PC measurement when the excitation light irradiated on the laser drilled holes. The spatial resolving of photoelectric property was achieved by the LBIC mapping which shows "pseudo-holes" with much larger dimensions than the geometric sizes of the holes. The reduced LBIC current with the pseudo-holes is associated with the redshift effect indicating that the electronic property of the rim areas of the holes is modified by the femtosecond laser drilling. PMID:26176477

  9. Spatially resolved energy dispersive x-ray spectroscopic method for in-situ evaluation of mechanical properties during the growth of a C - Pt composite nanowire

    NASA Astrophysics Data System (ADS)

    Banerjee, Amit; Banerjee, S. S.

    2014-05-01

    A core-shell type C-Pt composite nanowire is fabricated using focused ion and electron beam induced chemical vapor deposition techniques. Using information from spatially resolved energy dispersive x-ray spectra, we detect the resonance vibration in the C-Pt composite nanowire. We use this method to measure the Young's moduli of the constituents (C, Pt) of the composite nanowire and also estimate the density of the FEB CVD grown Pt shell surrounding the C core. By measuring the resonance characteristics of the composite nanowire we estimate a Pt shell growth rate of ˜0.9 nms-1. The study is analyzed to suggest that the Pt shell growth mechanism is primarily governed by the sticking coefficient of the organometallic vapor on the C nanowire core.

  10. Spatially resolved in situ determination of reaction progress using microfluidic systems and FT-IR spectroscopy as a tool for biocatalytic process development.

    PubMed

    Fagaschewski, Janosch; Sellin, Daniel; Wiedenhöfer, Charles; Bohne, Sven; Trieu, Hoc K; Hilterhaus, Lutz

    2015-07-01

    A concept for the determination of concentrations in microchannels using FT-IR spectroscopy in transmission is presented. The fundamental idea of spatially resolved measurements along several measuring points was implemented in a single-channel microreactor. Compared to existing microreactor setups for the analysis of fast chemical reactions or mixing processes, the presented concept enables longer residence times at appropriate resolution. Once steady-state conditions were reached in the reactor, mid-infrared spectra were collected at different locations. Information throughout the considered conversion range is available, which is of great importance to analyze inhibitory effects, next to the kinetic constants (vmax and KM). Therefore, this technology enables a rapid screening of (bio-)catalysts, substrate specificity and process conditions. In particular, the analysis of real substrates instead of model substrates and the possibility to follow side reactions and follow-up reactions during enzymatic catalysis open a broad field of application. PMID:25732540

  11. Continuous wave dye-laser technique for simultaneous, spatially resolved measurements of temperature, pressure, and velocity of NO in an underexpanded free jet

    NASA Technical Reports Server (NTRS)

    Di Rosa, Michael D.; Chang, Albert Y.; Hanson, Ronald K.

    1993-01-01

    Gas dynamic quantities within an underexpanded nitrogen free jet, seeded with 0.5 percent NO, were measured nonintrusively by using an intracavity-doubled, rapid-tuning, CW ring dye laser. The UV beam passed obliquely through the jet axis, and its frequency repetitively scanned across adjacent rotational lines in the NO gamma band near 225 nm at a rate of 4 kHz. Spatially resolved excitation scans were obtained by monitoring the induced broadband fluoresence. Modeling the Doppler-shifted excitation scans with Voigt profiles permitted simultaneous determinations of NO velocity, rotational temperature, and pressure. Zero Doppler shift was referenced to an absorption trace obtained across a static cell and recorded concurrently with the excitation scan. Typically, the measured and predicted axial distributions agreed within 10 percent. At high Mach numbers there was evidence of rotational freezing of NO.

  12. Spatially resolved energy dispersive x-ray spectroscopic method for in-situ evaluation of mechanical properties during the growth of a C - Pt composite nanowire

    SciTech Connect

    Banerjee, Amit; Banerjee, S. S.

    2014-05-15

    A core-shell type C-Pt composite nanowire is fabricated using focused ion and electron beam induced chemical vapor deposition techniques. Using information from spatially resolved energy dispersive x-ray spectra, we detect the resonance vibration in the C-Pt composite nanowire. We use this method to measure the Young's moduli of the constituents (C, Pt) of the composite nanowire and also estimate the density of the FEB CVD grown Pt shell surrounding the C core. By measuring the resonance characteristics of the composite nanowire we estimate a Pt shell growth rate of ∼0.9 nms{sup −1}. The study is analyzed to suggest that the Pt shell growth mechanism is primarily governed by the sticking coefficient of the organometallic vapor on the C nanowire core.

  13. High temporal and spatial resolution 3D time-resolved contrast-enhanced magnetic resonance angiography of the hands and feet.

    PubMed

    Haider, Clifton R; Riederer, Stephen J; Borisch, Eric A; Glockner, James F; Grimm, Roger C; Hulshizer, Thomas C; Macedo, Thanila A; Mostardi, Petrice M; Rossman, Phillip J; Vrtiska, Terri J; Young, Phillip M

    2011-07-01

    Methods are described for generating 3D time-resolved contrast-enhanced magnetic resonance (MR) angiograms of the hands and feet. Given targeted spatial resolution and frame times, it is shown that acceleration of about one order of magnitude or more is necessary. This is obtained by a combination of 2D sensitivity encoding (SENSE) and homodyne (HD) acceleration methods. Image update times from 3.4-6.8 seconds are provided in conjunction with view sharing. Modular receiver coil arrays are described which can be designed to the targeted vascular region. Images representative of the technique are generated in the vasculature of the hands and feet in volunteers and in patient studies. PMID:21698702

  14. Tempo-spatially resolved cellular dynamics of human immunodeficiency virus transacting activator of transcription (Tat) peptide-modified nanocargos in living cells

    NASA Astrophysics Data System (ADS)

    Wei, Lin; Yang, Qiaoyu; Xiao, Lehui

    2014-08-01

    Understanding the cellular uptake mechanism and intracellular fate of nanocarriers in living cells is of great importance for the rational design of efficient drug delivery cargos as well as the development of robust biomedical diagnostic probes. In present study, with a dual wavelength view darkfield microscope (DWVD), the tempo-spatially resolved dynamics of Tat peptide-functionalized gold nanoparticles (TGNPs, with size similar to viruses) in living HeLa cells were extensively explored. It was found that energy-dependent endocytosis (both clathrin- and caveolae-mediated processes were involved) was the prevailing pathway for the cellular uptake of TGNPs. The time-correlated dynamic spatial distribution information revealed that TGNPs could not actively target the cell nuclei, which is contrary to previous observations based on fixed cell results. More importantly, the inheritance of TGNPs to the daughter cells through mitosis was found to be the major route to metabolize TGNPs by HeLa cells. These understandings on the cellular uptake mechanism and intracellular fate of nanocargos in living cells would provide deep insight on how to improve and controllably manipulate their translocation efficiency for targeted drug delivery.Understanding the cellular uptake mechanism and intracellular fate of nanocarriers in living cells is of great importance for the rational design of efficient drug delivery cargos as well as the development of robust biomedical diagnostic probes. In present study, with a dual wavelength view darkfield microscope (DWVD), the tempo-spatially resolved dynamics of Tat peptide-functionalized gold nanoparticles (TGNPs, with size similar to viruses) in living HeLa cells were extensively explored. It was found that energy-dependent endocytosis (both clathrin- and caveolae-mediated processes were involved) was the prevailing pathway for the cellular uptake of TGNPs. The time-correlated dynamic spatial distribution information revealed that TGNPs

  15. CW dye laser technique for simultaneous, spatially-resolved measurements of temperature, pressure, and velocity of NO in an underexpanded free jet

    NASA Technical Reports Server (NTRS)

    Di Rosa, M. D.; Chang, A. Y.; Hanson, R. K.

    1992-01-01

    Gas dynamic quantities within an underexpanded free jet were measured nonintrusively using a rapid-tuning, CW ring dye laser. A nitrogen jet was seeded with 0.5 percent NO in N2, and the conditions were controlled such that a barrel shock formed. The frequency-doubled output of the dye laser was used to spectrally resolve rotational lines in the NO gamma band near 225 nm. With the rapid-tuning capability, these rotational spectra were acquired at a repetition rate of 4 kHz. Spatial resolution was afforded by monitoring the induced fluorescence via a lens and photomultiplier tube. Modeling the spectrally-resolved features with Voigt profiles permitted simultaneous measurements of NO velocity, rotational temperature, and pressure. Expansion of the jet was assumed to be isentropic, and agreement between measured and expected values was typically better than 10 percent over most of the Mach-number range encountered. At high Mach numbers, the measured rotational temperatures systematically departed from the isentropic temperature distribution. Such a measured departure could be ascribed to the onset of a non-Boltzmann distribution of NO rotational states.

  16. Spatially Resolved Electronic Alterations As Seen by in Situ 195Pt and 13CO NMR in Ru@Pt and Au@Pt Core-Shell Nanoparticles

    SciTech Connect

    Atienza, Dianne O.; Allison, Thomas C.; Tong, Yu ye J.

    2012-12-20

    Pt-based core-shell (M@Pt where M stands for core element) nanoparticles (NPs) have recently been under increasing scrutiny in the fields of fuel cell and lithium air battery electrocatalysis due to their promising prospects in optimizing catalytic activity, reducing Pt loading and consequently lowering its cost. To achieve the latter, delineating spatially resolved local (surface) elemental distribution and associated variations in electronic properties under working condition (i.e., in situ) is arguably a prerequisite of fundamental importance in investigating electrocatalysis but unfortunately is still sorely missing. In this regard, in situ 195Pt electrochemical NMR (EC-NMR) of Pt-based NPs is unique in terms of accessing such information, particularly the spatially resolved partition between the sand d-like Fermi level local density of states (Ef-LDOS) modified by the core elements. In this paper, we report a comparative in situ 195Pt EC-NMR investigation of Ru@Pt vs Au@Pt NPs which was complemented by in situ 13C EC-NMR of the 13CO adsorbed on the respective NPs generated via dissociation of methanol and by ab initio DFT calculations. The obtained results showed opposing electronic effect between Ru vs Au cores: the former reduced substantially the s-like but not the d-like Ef-LDOS of the Pt shell while the latter did the opposite. According to recent quantum calculations, a reduction in d-like partition would weaken the Pt-O bond while a reduction in s-like partition would weaken the Pt-H bond, which is largely in agreement with experimental observations.

  17. An Assessment of the Ability of Potential Spaceborne Instruments to Resolve Spatial and Temporal Variability of Atmospheric Carbon Dioxide

    NASA Technical Reports Server (NTRS)

    Andrews, Arlyn E.; Kawa, S. Randolph

    2001-01-01

    Mounting concern regarding the possibility that increasing carbon dioxide concentrations will initiate climate change has stimulated interest in the feasibility of measuring CO2 mixing ratios from satellites. Currently, the most comprehensive set of atmospheric CO2 data is from the NOAA CMDL cooperative air sampling network, consisting of more than 40 sites where flasks of air are collected approximately weekly. Sporadic observations in the troposphere and stratosphere from airborne in situ and flask samplers are also available. Although the surface network is extensive, there is a dearth of data in the Southern Hemisphere and most of the stations were intentionally placed in remote areas, far from major sources. Sufficiently precise satellite observations with adequate spatial and temporal resolution would substantially increase our knowledge of the atmospheric CO2 distribution and would undoubtedly lead to improved understanding of the global carbon budget. We use a 3-D chemical transport model to investigate the ability of potential satellite instruments with a variety of orbits, horizontal resolution and vertical weighting functions to capture the variation in the modeled CO2 fields. The model is driven by analyzed winds from the Goddard Data Assimilation Office. Simulated CO2 fields are compared with existing surface and aircraft data, and the effects of the model convection scheme and representation of the planetary boundary layer are considered.

  18. Geochemistry of Dissolved Organic Matter in a Spatially Highly Resolved Groundwater Petroleum Hydrocarbon Plume Cross-Section.

    PubMed

    Dvorski, Sabine E-M; Gonsior, Michael; Hertkorn, Norbert; Uhl, Jenny; Müller, Hubert; Griebler, Christian; Schmitt-Kopplin, Philippe

    2016-06-01

    At numerous groundwater sites worldwide, natural dissolved organic matter (DOM) is quantitatively complemented with petroleum hydrocarbons. To date, research has been focused almost exclusively on the contaminants, but detailed insights of the interaction of contaminant biodegradation, dominant redox processes, and interactions with natural DOM are missing. This study linked on-site high resolution spatial sampling of groundwater with high resolution molecular characterization of DOM and its relation to groundwater geochemistry across a petroleum hydrocarbon plume cross-section. Electrospray- and atmospheric pressure photoionization (ESI, APPI) ultrahigh resolution mass spectrometry (FT-ICR-MS) revealed a strong interaction between DOM and reactive sulfur species linked to microbial sulfate reduction, i.e., the key redox process involved in contaminant biodegradation. Excitation emission matrix (EEM) fluorescence spectroscopy in combination with Parallel Factor Analysis (PARAFAC) modeling attributed DOM samples to specific contamination traits. Nuclear magnetic resonance (NMR) spectroscopy evaluated the aromatic compounds and their degradation products in samples influenced by the petroleum contamination and its biodegradation. Our orthogonal high resolution analytical approach enabled a comprehensive molecular level understanding of the DOM with respect to in situ petroleum hydrocarbon biodegradation and microbial sulfate reduction. The role of natural DOM as potential cosubstrate and detoxification reactant may improve future bioremediation strategies. PMID:27152868

  19. Spatially resolved charge-state and current-density distributions at the extraction of an electron cyclotron resonance ion source

    SciTech Connect

    Panitzsch, Lauri; Peleikis, Thies; Stalder, Michael; Wimmer-Schweingruber, Robert F.

    2011-09-15

    In this paper we present our measurements of charge-state and current-density distributions performed in very close vicinity (15 mm) of the extraction of our hexapole geometry electron cyclotron resonance ion source. We achieved a relatively high spatial resolution reducing the aperture of our 3D-movable extraction (puller) electrode to a diameter of only 0.5 mm. Thus, we are able to limit the source of the extracted ion beam to a very small region of the plasma electrode's hole (O = 4 mm) and therefore to a very small region of the neutral plasma sheath. The information about the charge-state distribution and the current density in the plane of the plasma electrode at each particular position is conserved in the ion beam. We determined the total current density distribution at a fixed coaxial distance of only 15 mm to the plasma electrode by remotely moving the small-aperture puller electrode which contained a dedicated Faraday cup (FC) across the aperture of the plasma electrode. In a second measurement we removed the FC and recorded m/q-spectra for the different positions using a sector magnet. From our results we can deduce that different ion charge-states can be grouped into bloated triangles of different sizes and same orientation at the extraction with the current density peaking at centre. This confirms observations from other groups based on simulations and emittance measurements. We present our measurements in detail and discuss possible systematic errors.

  20. Studies of Shear Band Velocity Using Spatially and Temporally Resolved Measurements of Strain During Quasistatic Compression of Bulk Metallic Glass

    SciTech Connect

    Wright, W J; Samale, M; Hufnagel, T; LeBlanc, M; Florando, J

    2009-06-15

    We have made measurements of the temporal and spatial features of the evolution of strain during the serrated flow of Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass tested under quasistatic, room temperature, uniaxial compression. Strain and load data were acquired at rates of up to 400 kHz using strain gages affixed to all four sides of the specimen and a piezoelectric load cell located near the specimen. Calculation of the displacement rate requires an assumption about the nature of the shear displacement. If one assumes that the entire shear plane displaces simultaneously, the displacement rate is approximately 0.002 m/s. If instead one assumes that the displacement occurs as a localized propagating front, the velocity of the front is approximately 2.8 m/s. In either case, the velocity is orders of magnitude less than the shear wave speed ({approx}2000 m/s). The significance of these measurements for estimates of heating in shear bands is discussed.

  1. Spatially Resolved Spectra from a new X-ray Imaging Crystal Spectrometer for Measurements of Ion and Electron Temperature Profiles

    SciTech Connect

    Bitter, M; Stratton, B; Roquemore, A; Mastrovito, D; Lee, S; Bak, J; Moon, M; Nam, U; Smith, G; Rice, J; Beiersdorfer, P; Fraenkel, B

    2004-08-10

    A new type of high-resolution X-ray imaging crystal spectrometer is being developed to measure ion and electron temperature profiles in tokamak plasmas. The instrument is particularly valuable for diagnosing plasmas with purely Ohmic heating and rf heating, since it does not require the injection of a neutral beam - although it can also be used for the diagnosis of neutral-beam heated plasmas. The spectrometer consists of a spherically bent quartz crystal and a two-dimensional position-sensitive detector. It records spectra of helium-like argon (or krypton) from multiple sightlines through the plasma and projects a de-magnified image of a large plasma cross-section onto the detector. The spatial resolution in the plasma is solely determined by the height of the crystal, its radius of curvature, and the Bragg angle. This new X-ray imaging crystal spectrometer may also be of interest for the diagnosis of ion temperature profiles in future large tokamaks, such as KSTAR and ITER, where the application of the presently used charge-exchange spectroscopy will be difficult, if the neutral beams do not penetrate to the plasma center. The paper presents the results from proof-of-principle experiments performed with a prototype instrument at Alcator C-Mod.

  2. Spatially Resolved Photoexcited Charge-Carrier Dynamics in Phase-Engineered Monolayer MoS2

    SciTech Connect

    Yamaguchi, Hisato; Blancon, Jean-Christophe; Kappera, Rajesh; Lei, Sidong; Najmaei, Sina; Mangum, Benjamin D.; Gupta, Gautam; Ajayan, Pulickel M.; Lou, Jun; Chhowalla, Manish; Crochet, Jared J.; Mohite, Aditya D.

    2014-12-18

    A fundamental understanding of the intrinsic optoelectronic properties of atomically thin transition metal dichalcogenides (TMDs) is crucial for its integration into high performance semiconductor devices. We investigate the transport properties of chemical vapor deposition (CVD) grown monolayer molybdenum disulfide (MoS2) under photo-excitation using correlated scanning photocurrent microscopy and photoluminescence imaging. We examined the effect of local phase transformation underneath the metal electrodes on the generation of photocurrent across the channel length with diffraction-limited spatial resolution. While maximum photocurrent generation occurs at the Schottky contacts of semiconducting (2H-phase) MoS2, after the metallic phase transformation (1T-phase), the photocurrent peak is observed towards the center of the device channel, suggesting a strong reduction of native Schottky barriers. Analysis using the bias and position dependence of the photocurrent indicates that the Schottky barrier heights are few meV for 1T- and ~200 meV for 2H-contacted devices. We also demonstrate that a reduction of native Schottky barriers in a 1T device enhances the photo responsivity by more than one order of magnitude, a crucial parameter in achieving high performance optoelectronic devices. The obtained results pave a pathway for the fundamental understanding of intrinsic optoelectronic properties of atomically thin TMDs where Ohmic contacts are necessary for achieving high efficiency devices with low power consumption.

  3. Spatially Resolved Stellar Populations Of Nearby Post-Starburst Galaxies In SDSS-IV MaNGA

    NASA Astrophysics Data System (ADS)

    Liu, Charles; Betances, Ashley; Bonilla, Alaina Marie; Gonzalez, Andrea; Migliore, Christina; Goddard, Daniel; Masters, Karen; SDSS-IV MaNGA Team

    2016-01-01

    We have selected five galaxies in the Mapping Nearby Galaxies at APO (MaNGA) project of the latest generation of the Sloan Digital Sky Survey (SDSS-IV) identified as post-starburst (E+A) systems, in the transition between "blue cloud" and "red sequence" galaxies. We measure the equivalent widths of the Balmer series, D4000 break, and metal lines across each galaxy, and produce maps of the stellar age, stellar mass, and metallicities of each galaxy using FIREFLY, a full spectral analysis code. We have found that the measured properties of the galaxies overall generally matches well with single-aperture SDSS spectra from which the original post-starburst identifications were made. The variation in the spatial distributions of the stellar populations, in particular the A-stars, give us insight into the details of the transitional E+A quenching phase. This work was supported by the Alfred P. Sloan Foundation via the SDSS-IV Faculty and Student Team (FAST) initiative, ARC Agreement No. SSP483 to the CUNY College of Staten Island.

  4. A multiscale computational model of spatially resolved calcium cycling in cardiac myocytes: from detailed cleft dynamics to the whole cell concentration profiles

    PubMed Central

    Vierheller, Janine; Neubert, Wilhelm; Falcke, Martin; Gilbert, Stephen H.; Chamakuri, Nagaiah

    2015-01-01

    Mathematical modeling of excitation-contraction coupling (ECC) in ventricular cardiac myocytes is a multiscale problem, and it is therefore difficult to develop spatially detailed simulation tools. ECC involves gradients on the length scale of 100 nm in dyadic spaces and concentration profiles along the 100 μm of the whole cell, as well as the sub-millisecond time scale of local concentration changes and the change of lumenal Ca2+ content within tens of seconds. Our concept for a multiscale mathematical model of Ca2+ -induced Ca2+ release (CICR) and whole cardiomyocyte electrophysiology incorporates stochastic simulation of individual LC- and RyR-channels, spatially detailed concentration dynamics in dyadic clefts, rabbit membrane potential dynamics, and a system of partial differential equations for myoplasmic and lumenal free Ca2+ and Ca2+-binding molecules in the bulk of the cell. We developed a novel computational approach to resolve the concentration gradients from dyadic space to cell level by using a quasistatic approximation within the dyad and finite element methods for integrating the partial differential equations. We show whole cell Ca2+-concentration profiles using three previously published RyR-channel Markov schemes. PMID:26441674

  5. CARMA INTERFEROMETRIC OBSERVATIONS OF 2MASS J044427+2512: THE FIRST SPATIALLY RESOLVED OBSERVATIONS OF THERMAL EMISSION OF A BROWN DWARF DISK

    SciTech Connect

    Ricci, L.; Isella, A.; Carpenter, J. M.; Testi, L.

    2013-02-20

    We present CARMA 1.3 mm continuum data of the disk surrounding the young brown dwarf 2MASS J044427+2512 in the Taurus molecular cloud. The high angular resolution of the CARMA observations (0.''16) allows us to spatially resolve for the first time the thermal emission from dust around a brown dwarf. We analyze the interferometric visibilities and constrain the disk outer radius adopting disk models with power-law radial profiles of the dust surface density. In the case of a power-law index {<=}1, we obtain a disk radius in the range of about 15-30 AU, while larger disks are inferred for steeper radial profiles. By combining this information on the disk spatial extent with the sub-mm spectral index of this source, we find conclusive evidence for mm-sized grains, or larger, in this brown dwarf disk. We discuss the implications of our results on the models of dust evolution in protoplanetary disks and brown dwarf formation.

  6. Spatially Resolved Spectroscopy of a Balmer-dominated Shock in the Cygnus Loop: An Extremely Thin Cosmic-Ray Precursor?

    NASA Astrophysics Data System (ADS)

    Katsuda, Satoru; Maeda, Keiichi; Ohira, Yutaka; Yatsu, Yoichi; Mori, Koji; Aoki, Wako; Morihana, Kumiko; Raymond, John C.; Ghavamian, Parviz; Lee, Jae-Joon; Shimoda, Jiro; Yamazaki, Ryo

    2016-03-01

    We present high-resolution long-slit spectroscopy of a Balmer-dominated shock in the northeastern limb of the Cygnus Loop with the Subaru high dispersion spectrograph. By setting the slit angle along the shock normal, we investigate variations of the flux and profile of the Hα line from preshock to postshock regions with a spatial resolution of ˜4 × 1015 cm. The Hα line profile can be represented by a narrow (28.9 ± 0.7 km s-1) Gaussian in a diffuse region ahead of the shock, i.e., a photoionization precursor, and narrow (33.1 ± 0.2 km s-1) plus broad (130-230 km s-1) Gaussians at the shock itself. We find that the width of the narrow component abruptly increases up to 33.1 ± 0.2 km s-1, or 38.8 ± 0.4 km s-1 if we eliminate projected emission originating from the photoionization precursor, in an unresolved thin layer (≲4 × 1015 cm at a distance of 540 pc) at the shock. We show that the sudden broadening can be best explained by heating via damping of Alfvén waves in a thin cosmic-ray (CR) precursor, although other possibilities are not fully ruled out. The thickness of the CR precursor in the Cygnus Loop (a soft gamma-ray emitter) is an order of magnitude thinner than that in Tycho’s Knot g (a hard gamma-ray emitter), which may be caused by the different energy distribution of accelerated particles between the two sources. In this context, systematic studies might reveal a positive correlation between the thickness of the CR precursor and the hardness of the CR energy distribution.

  7. Resolving spatial heterogeneities in exhumation and surface uplift in Timor-Leste: Constraints on deformation processes in young orogens

    NASA Astrophysics Data System (ADS)

    Tate, Garrett W.; McQuarrie, Nadine; Hinsbergen, Douwe J. J.; Bakker, Richard R.; Harris, Ron; Willett, Sean; Reiners, Peter W.; Fellin, Maria Giuditta; Ganerød, Morgan; Zachariasse, Willem Jan

    2014-06-01

    Although exhumation and surface uplift are important parameters in understanding orogenesis, the opportunity to measure both in close proximity is rare. In Timor-Leste (East Timor), deeply exhumed metamorphic rocks and piggyback deepwater synorogenic basins are only tens of kilometers apart, permitting direct relation of uplift and exhumation by comparing micropaleontology to thermochronology interpreted through one-dimensional thermal modeling. Foraminifera in two deepwater synorogenic basins suggest basin uplift from depths of 1-2 km to depths of 350-1000 m between 3.35 and 1.88 Ma. Thermochronologic sampling was conducted in the central mountain belt between these basins. Of four muscovite 40Ar/39Ar samples, one provides a reset age of 7.13 ± 0.25 Ma in the Aileu high-grade belt that suggests ~9-16 km of exhumation since that time. Eighteen zircon (U-Th)/He samples contain a group of reset ages in the Aileu Complex ranging from 4.4 to 1.5 Ma, which suggest exhumation rates of 1.0-3.1 mm/yr with 2.7-7.8 km of exhumation since these ages. Thirteen apatite (U-Th)/He ages in the Gondwana Sequence range from 5.5 to 1.4 Ma, suggesting 1-2 km of exhumation and defining a pattern of exhumation rates (ranging from 0.2 to 1.3 mm/yr) that positively correlates with average annual rainfall. Seven apatite fission track samples display varying degrees of partial resetting, with greatest resetting where apatite (U-Th)/He ages are youngest. Together, these data demonstrate extreme variability in surface uplift and exhumation over small spatial scales. We propose ongoing subsurface duplexing driven by subduction and underplating of Australian continental crust as the predominant driver for surface uplift and uplift-induced exhumation.

  8. Using 2D correlation analysis to enhance spectral information available from highly spatially resolved AFM-IR spectra

    NASA Astrophysics Data System (ADS)

    Marcott, Curtis; Lo, Michael; Hu, Qichi; Kjoller, Kevin; Boskey, Adele; Noda, Isao

    2014-07-01

    The recent combination of atomic force microscopy and infrared spectroscopy (AFM-IR) has led to the ability to obtain IR spectra with nanoscale spatial resolution, nearly two orders-of-magnitude better than conventional Fourier transform infrared (FT-IR) microspectroscopy. This advanced methodology can lead to significantly sharper spectral features than are typically seen in conventional IR spectra of inhomogeneous materials, where a wider range of molecular environments are coaveraged by the larger sample cross section being probed. In this work, two-dimensional (2D) correlation analysis is used to examine position sensitive spectral variations in datasets of closely spaced AFM-IR spectra. This analysis can reveal new key insights, providing a better understanding of the new spectral information that was previously hidden under broader overlapped spectral features. Two examples of the utility of this new approach are presented. Two-dimensional correlation analysis of a set of AFM-IR spectra were collected at 200-nm increments along a line through a nucleation site generated by remelting a small spot on a thin film of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). There are two different crystalline carbonyl band components near 1720 cm-1 that sequentially disappear before a band at 1740 cm-1 due to more disordered material appears. In the second example, 2D correlation analysis of a series of AFM-IR spectra spaced every 1 μm of a thin cross section of a bone sample measured outward from an osteon center of bone growth. There are many changes in the amide I and phosphate band contours, suggesting changes in the bone structure are occurring as the bone matures.

  9. Policy applications of a highly resolved spatial and temporal onroad carbon dioxide emissions data product for the U.S.: Analyses and their implications for mitigation

    NASA Astrophysics Data System (ADS)

    Mendoza Lebrun, Daniel

    Onroad CO2 emissions were analyzed as part of overall GHG emissions, but those studies have suffered from one or more of these five shortcomings: 1) the spatial resolution was coarse, usually encompassing a region, or the entire U.S.; 2) the temporal resolution was coarse (annual or monthly); 3) the study region was limited, usually a metropolitan planning organization (MPO) or state; 4) fuel sales were used as a proxy to quantify fuel consumption instead of focusing on travel; 5) the spatial heterogeneity of fleet and road network composition was not considered and instead national averages are used. Normalized vehicle-type state-level spatial biases range from 2.6% to 8.1%, while the road type classification biases range from -6.3% to 16.8%. These biases are found to cause errors in reduction estimates as large as ±60%, corresponding to ±0.2 MtC, for a national-average emissions mitigation strategy focused on a 10% emissions reduction from a single vehicle class. Temporal analysis shows distinct emissions seasonality that is particularly visible in the northernmost latitudes, demonstrating peak-to-peak deviations from the annual mean of up to 50%. The hourly structure shows peak-to-peak deviation from a weekly average of up to 200% for heavy-duty (HD) vehicles and 140% for light-duty (LD) vehicles. The present study focuses on reduction of travel and fuel economy improvements by putting forth several mitigation scenarios aimed at reducing VMT and increasing vehicle fuel efficiency. It was found that the most effective independent reduction strategies are those that increase fuel efficiency by extending standards proposed by the corporate average fuel economy (CAFE) or reduction of fuel consumption due to price increases. These two strategies show cumulative emissions reductions of approximately 11% and 12%, respectively, from a business as usual (BAU) approach over the 2000-2050 period. The U.S. onroad transportation sector is long overdue a comprehensive study

  10. Spatially resolved physical conditions of molecular gas and potential star formation tracers in M 83, revealed by the Herschel SPIRE FTS

    NASA Astrophysics Data System (ADS)

    Wu, R.; Madden, S. C.; Galliano, F.; Wilson, C. D.; Kamenetzky, J.; Lee, M.-Y.; Schirm, M.; Hony, S.; Lebouteiller, V.; Spinoglio, L.; Cormier, D.; Glenn, J.; Maloney, P. R.; Pereira-Santaella, M.; Rémy-Ruyer, A.; Baes, M.; Boselli, A.; Bournaud, F.; De Looze, I.; Hughes, T. M.; Panuzzo, P.; Rangwala, N.

    2015-03-01

    We investigate the physical properties of the molecular and ionized gas, and their relationship to the star formation and dust properties in M 83, based on submillimeter imaging spectroscopy from within the central 3.5' (~4 kpc in diameter) around the starburst nucleus. The observations use the Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) onboard the Herschel Space Observatory. The newly observed spectral lines include [CI] 370 μm, [CI] 609 μm, [NII] 205 μm, and CO transitions from J = 4-3 to J = 13-12. Combined with previously observed J = 1-0 to J = 3-2 transitions, the CO spectral line energy distributions are translated to spatially resolved physical parameters, column density of CO, N(CO), and molecular gas thermal pressure, Pth, with a non-local thermal equilibrium (non-LTE) radiative transfer model, RADEX. Our results show that there is a relationship between the spatially resolved intensities of [NII] 205 μm and the surface density of the star formation rate (SFR), ΣSFR. This relation, when compared to integrated properties of ultra-luminous infrared galaxies (ULIRGs), exhibits a different slope, because the [NII] 205 μm distribution is more extended than the SFR. The spatially resolved [CI] 370 μm, on the other hand, shows a generally linear relationship with ΣSFR and can potentially be a good SFR tracer. Compared with the dust properties derived from broad-band images, we find a positive trend between the emissivity of CO in the J = 1-0 transition with the average intensity of interstellar radiation field (ISRF), ⟨ U ⟩. This trend implies a decrease in the CO-to-H2 conversion factor, XCO, when ⟨ U ⟩ increases. We estimate the gas-to-dust mass ratios to be 77 ± 33 within the central 2 kpc and 93 ± 19 within the central 4 kpc of M 83, which implies a Galactic dust-to-metal mass ratio within the observed region of M 83. The estimated gas-depletion time for the M 83 nucleus is 1.13 ± 0.6 Gyr

  11. Clouds and aerosols on Uranus: Radiative transfer modeling of spatially-resolved near-infrared Keck spectra

    NASA Astrophysics Data System (ADS)

    de Kleer, Katherine; Luszcz-Cook, Statia; de Pater, Imke; Ádámkovics, Máté; Hammel, H. B.

    2015-08-01

    We observed Uranus in the near-infrared H and K‧ bands (1.47-2.38 μ m) in 2010 and 2011 with the OSIRIS imaging spectrograph on the Keck II telescope with adaptive optics. In 2010, three years past the equinox, we had a good view of the north polar region while still having access to southern latitudes down to 70°S. In 2011 our observations focused on a moderately bright discrete cloud feature in the middle of the bright circumpolar band at 45°N. The spatial and spectral resolution of our data allow us to retrieve atmospheric parameters between ∼65°S and 75°N via radiative transfer modeling. We test vertical aerosol profiles with combinations of diffuse and compact scattering layers, and find that we can reproduce our equatorial data for a range of cases, provided the deepest detectable aerosol layer is compact and located between 2 and 3 bars, with the higher cloud altitudes corresponding to models with higher methane deep volume mixing ratios. Using a parameterized atmosphere with a diffuse upper haze and a moderately compact lower cloud, we find that both the haze and the cloud reach their maximal optical depth just north of the equator and thin toward the poles. When we fix the abundance of methane with latitude, we find that the bottom cloud shifts to shallower depths at higher latitudes in both hemispheres; for a methane profile with a deep volume mixing ratio of 2.22%, the cloud rises from the 3-bar level equatorward of ±20° to above 2 bars by ±60°. However, when we allow the tropospheric methane abundance to vary according to a parameterized vertical profile, we find that the lower cloud depth is stable in latitude while the methane becomes increasingly depleted toward both poles. In both cases, we find denser aerosol layers and higher methane abundances in the northern hemisphere than the southern, consistent with a seasonal post-equinox trend. In particular, the bright band near 45°N is relatively undepleted in methane, and represents a

  12. Spatially resolved NRM of the Bishunpur LL3.1 chondrite measured by scanning SQUID microscopy: implications for chondrule formation

    NASA Astrophysics Data System (ADS)

    Church, N. S.; Andrade Lima, E.; Lappe, S. L.; Russell, S.; Weiss, B. P.; Harrison, R. J.

    2012-12-01

    Chondrites represent the building blocks of the solar system and the factors controlling their formation have implications for processes within the protoplanetary disk and interactions between the solar nebula and the early Sun. However, the source of the flash heating that formed the constituent chondrules is a subject of debate, with proposed mechanisms including various forms of convection drawing nebular dust towards and ejecting it away from the Sun, or alternatively extra-nebular energy pulses that require no interaction with the young star. Because the Sun was strongly magnetic early in its life, paleointensity measurements of chondrules can be used to determine the distance at which they cooled through their Curie temperature, providing evidence about which formation mechanism caused their melting and potentially shedding light on accretionary processes within the protoplanetary disk. The Bishunpur LL3.1 meteorite is among the most pristine ordinary chondrites, having both limited thermal and aqueous alteration and a known (magnetic) history on Earth. As such, its chondrules have the potential to preserve primary remanence from their formation if the recorders are capable of maintaining a stable magnetic state over timescales greater than 4.6 Ga. Previous work has shown that dusty olivine—iron nanoparticle-bearing silicate that constitutes a proportion of the chondrules of Bishunpur—is an stable recorder over these timescales even at temperatures approaching the Curie temperature of iron. In bulk measurements, however, the paleointensity signal from the chondrules is masked by magnetic phases on chondrule rims and in the matrix, necessitating a technique that allows the contribution of different signals to be distinguished. Scanning SQUID microscopy presents an ideal solution as it produces a map of magnetic field measurements with a spatial resolution of 10s of μm from which the absolute magnetization can be calculated, allowing the paleointensity and

  13. SPATIALLY RESOLVING A STARBURST GALAXY AT HARD X-RAY ENERGIES: NuSTAR, CHANDRA, AND VLBA OBSERVATIONS OF NGC 253

    SciTech Connect

    Wik, D. R.; Lehmer, B. D.; Hornschemeier, A. E.; Yukita, M.; Ptak, A.; Venters, T.; Zhang, W. W.; Zezas, A.; Antoniou, V.; Argo, M. K.; Bechtol, K.; Boggs, S.; Craig, W.; Krivonos, R.; Christensen, F.; Hailey, C.; Harrison, F.; Maccarone, T. J.; Stern, D.

    2014-12-20

    Prior to the launch of NuSTAR, it was not feasible to spatially resolve the hard (E > 10 keV) emission from galaxies beyond the Local Group. The combined NuSTAR data set, comprised of three ∼165 ks observations, allows spatial characterization of the hard X-ray emission in the galaxy NGC 253 for the first time. As a follow up to our initial study of its nuclear region, we present the first results concerning the full galaxy from simultaneous NuSTAR, Chandra, and Very Long Baseline Array monitoring of the local starburst galaxy NGC 253. Above ∼10 keV, nearly all the emission is concentrated within 100'' of the galactic center, produced almost exclusively by three nuclear sources, an off-nuclear ultraluminous X-ray source (ULX), and a pulsar candidate that we identify for the first time in these observations. We detect 21 distinct sources in energy bands up to 25 keV, mostly consisting of intermediate state black hole X-ray binaries. The global X-ray emission of the galaxy—dominated by the off-nuclear ULX and nuclear sources, which are also likely ULXs—falls steeply (photon index ≳ 3) above 10 keV, consistent with other NuSTAR-observed ULXs, and no significant excess above the background is detected at E > 40 keV. We report upper limits on diffuse inverse Compton emission for a range of spatial models. For the most extended morphologies considered, these hard X-ray constraints disfavor a dominant inverse Compton component to explain the γ-ray emission detected with Fermi and H.E.S.S. If NGC 253 is typical of starburst galaxies at higher redshift, their contribution to the E > 10 keV cosmic X-ray background is <1%.

  14. The Topographic Organization of Retinal Ganglion Cell Density and Spatial Resolving Power in an Unusual Arboreal and Slow-Moving Strepsirhine Primate, the Potto (Perodicticus potto).

    PubMed

    Coimbra, João Paulo; Kaswera-Kyamakya, Consolate; Gilissen, Emmanuel; Manger, Paul R; Collin, Shaun P

    2016-01-01

    The potto (Perodicticus potto) is an arboreal strepsirhine found in the rainforests of central Africa. In contrast to most primates, the potto shows slow-moving locomotion over the upper surface of branches, where it forages for exudates and crawling invertebrates with its head held very close to the substrate. Here, we asked whether the retina of the potto displays topographic specializations in neuronal density that correlate with its unusual lifestyle. Using stereology and retinal wholemounts, we measured the total number and topographic distribution of retinal ganglion cells (total and presumed parasol), as well as estimating the upper limits of the spatial resolution of the potto eye. We estimated ∼210,000 retinal ganglion cells, of which ∼7% (∼14,000) comprise presumed parasol ganglion cells. The topographic distribution of both total and parasol ganglion cells reveals a concentric centroperipheral organization with a nasoventral asymmetry. Combined with the upwardly shifted orbits of the potto, this nasoventral increase in parasol ganglion cell density enhances contrast sensitivity and motion detection skywards, which potentially assists with the detection of predators in the high canopy. The central area of the potto occurs ∼2.5 mm temporal to the optic disc and contains a maximum ganglion cell density of ∼4,300 cells/mm2. We found no anatomical evidence of a fovea within this region. Using maximum ganglion cell density and eye size (∼14 mm), we estimated upper limits of spatial resolving power between 4.1 and 4.4 cycles/degree. Despite their reported reliance on olfaction to detect exudates, this level of spatial resolution potentially assists pottos with foraging for small invertebrates and in the detection of predators. PMID:26820506

  15. Spatially resolved estimation of ozone-related mortality in the United States under two Representative Concentration Pathways (RCPs) and their uncertainty

    PubMed Central

    Kim, Young-Min; Zhou, Ying; Gao, Yang; Fu, Joshua S.; Johnson, Brent A.; Huang, Cheng; Liu, Yang

    2014-01-01

    The spatial pattern of the uncertainty in air pollution-related health impacts due to climate change has rarely been studied due to the lack of high-resolution model simulations, especially under the Representative Concentration Pathways (RCPs), the latest greenhouse gas emission pathways. We estimated future tropospheric ozone (O3) and related excess mortality and evaluated the associated uncertainties in the continental United States under RCPs. Based on dynamically downscaled climate model simulations, we calculated changes in O3 level at 12 km resolution between the future (2057–2059) and base years (2001–2004) under a low-to-medium emission scenario (RCP4.5) and a fossil fuel intensive emission scenario (RCP8.5). We then estimated the excess mortality attributable to changes in O3. Finally, we analyzed the sensitivity of the excess mortality estimates to the input variables and the uncertainty in the excess mortality estimation using Monte Carlo simulations. O3-related premature deaths in the continental U.S. were estimated to be 1,312 deaths/year under RCP8.5 (95% confidence interval (CI): 427 to 2,198) and −2,118 deaths/year under RCP4.5 (95% CI: −3,021 to −1,216), when allowing for climate change and emissions reduction. The uncertainty of O3-related excess mortality estimates was mainly caused by RCP emissions pathways. Excess mortality estimates attributable to the combined effect of climate and emission changes on O3 as well as the associated uncertainties vary substantially in space and so do the most influential input variables. Spatially resolved data is crucial to develop effective community level mitigation and adaptation policy. PMID:25530644

  16. Spatially resolved estimation of ozone-related mortality in the United States under two representative concentration pathways (RCPs) and their uncertainty

    DOE PAGESBeta

    Kim, Young-Min; Zhou, Ying; Gao, Yang; Fu, Joshua S.; Johnson, Brent A.; Huang, Cheng; Liu, Yang

    2014-11-16

    We report that the spatial pattern of the uncertainty in air pollution-related health impacts due to climate change has rarely been studied due to the lack of high-resolution model simulations, especially under the Representative Concentration Pathways (RCPs), the latest greenhouse gas emission pathways. We estimated future tropospheric ozone (O3) and related excess mortality and evaluated the associated uncertainties in the continental United States under RCPs. Based on dynamically downscaled climate model simulations, we calculated changes in O3 level at 12 km resolution between the future (2057 and 2059) and base years (2001–2004) under a low-to-medium emission scenario (RCP4.5) and amore » fossil fuel intensive emission scenario (RCP8.5). We then estimated the excess mortality attributable to changes in O3. Finally, we analyzed the sensitivity of the excess mortality estimates to the input variables and the uncertainty in the excess mortality estimation using Monte Carlo simulations. O3-related premature deaths in the continental U.S. were estimated to be 1312 deaths/year under RCP8.5 (95 % confidence interval (CI): 427 to 2198) and ₋2118 deaths/year under RCP4.5 (95 % CI: ₋3021 to ₋1216), when allowing for climate change and emissions reduction. The uncertainty of O3-related excess mortality estimates was mainly caused by RCP emissions pathways. Finally, excess mortality estimates attributable to the combined effect of climate and emission changes on O3 as well as the associated uncertainties vary substantially in space and so do the most influential input variables. Spatially resolved data is crucial to develop effective community level mitigation and adaptation policy.« less

  17. Spatially Resolved Estimation of Ozone-related Mortality in the United States under Two Representative Concentration Pathways (RCPs) and their Uncertainty

    SciTech Connect

    Kim, Young-Min; Zhou, Ying; Gao, Yang; Fu, Joshua S.; Johnson, Brent; Huang, Cheng; Liu, Yang

    2015-01-01

    BACKGROUND: The spatial pattern of the uncertainty in climate air pollution health impact has rarely been studied due to the lack of high-resolution model simulations, especially under the latest Representative Concentration Pathways (RCPs). OBJECTIVES: We estimated county-level ozone (O3) and PM2.5 related excess mortality (EM) and evaluated the associated uncertainties in the continental United States in the 2050s under RCP4.5 and RCP8.5. METHODS: Using dynamically downscaled climate model simulations, we calculated changes in O3 and PM2.5 levels at 12 km resolution between the future (2057-2059) and present (2001-2004) under two RCP scenarios. Using concentration-response relationships in the literature and projected future populations, we estimated EM attributable to the changes in O3 and PM2.5. We finally analyzed the contribution of input variables to the uncertainty in the county-level EM estimation using Monte Carlo simulation. RESULTS: O3-related premature deaths in the continental U.S. were estimated to be 1,082 deaths/year under RCP8.5 (95% confidence interval (CI): -288 to 2,453), and -5,229 deaths/year under RCP4.5 (-7,212 to -3,246). Simulated PM2.5 changes resulted in a significant decrease in EM under the two RCPs. The uncertainty of O3-related EM estimates was mainly caused by RCP scenarios, whereas that of PM2.5-related EMs was mainly from concentration-response functions. CONCLUSION: EM estimates attributable to climate change-induced air pollution change as well as the associated uncertainties vary substantially in space, and so are the most influential input variables. Spatially resolved data is crucial to develop effective mitigation and adaptation pol