Science.gov

Sample records for color photon echo

  1. Excitation of photon echo by noise pulses

    NASA Astrophysics Data System (ADS)

    Baruzdin, S. A.

    2016-10-01

    The excitation of photon echo by noise pulses that are formed by modulation of the carrying frequency with Gauss noise is modeled. The modeling is based on optical Bloch equations the solution of which for noise pulse realizations is constructed by their stepwise approximation. In terms of the formalism of state transfer matrices, the two- and three-pulse excitation modes are analyzed. The complex envelopes of the primary and stimulated echo responses are determined. In the linear (low-level-signal) mode, the shape of the two-pulse echo corresponds to that of the time delayed and inverted noise pulse. The boundary of the linear mode, upon exceeding of which distortions of the shape of the noise pulse become noticeable, is determined. The shape of the stimulated (three-pulse) echo in the linear mode corresponds to that of the autocorrelation function of the noise pulse realization. Upon passage beyond the boundary of the linear mode, the shape of the three-pulse echo corresponds either to the cross-correlation function of distorted noise pulses (with different intensities) or to the autocorrelation function of distorted pulses (with the same intensities). The modeled photon echo excitation modes can be used in photon echo processors to process signals in the light range.

  2. Photon echo studies of photosynthetic light harvesting.

    PubMed

    Read, Elizabeth L; Lee, Hohjai; Fleming, Graham R

    2009-01-01

    The broad linewidths in absorption spectra of photosynthetic complexes obscure information related to their structure and function. Photon echo techniques represent a powerful class of time-resolved electronic spectroscopy that allow researchers to probe the interactions normally hidden under broad linewidths with sufficient time resolution to follow the fastest energy transfer events in light harvesting. Here, we outline the technical approach and applications of two types of photon echo experiments: the photon echo peak shift and two-dimensional (2D) Fourier transform photon echo spectroscopy. We review several extensions of these techniques to photosynthetic complexes. Photon echo peak shift spectroscopy can be used to determine the strength of coupling between a pigment and its surrounding environment including neighboring pigments and to quantify timescales of energy transfer. Two-dimensional spectroscopy yields a frequency-resolved map of absorption and emission processes, allowing coupling interactions and energy transfer pathways to be viewed directly. Furthermore, 2D spectroscopy reveals structural information such as the relative orientations of coupled transitions. Both classes of experiments can be used to probe the quantum mechanical nature of photosynthetic light-harvesting: peak shift experiments allow quantification of correlated energetic fluctuations between pigments, while 2D techniques measure quantum beating directly, both of which indicate the extent of quantum coherence over multiple pigment sites in the protein complex. The mechanistic and structural information obtained by these techniques reveals valuable insights into the design principles of photosynthetic light-harvesting complexes, and a multitude of variations on the methods outlined here.

  3. All-optical photon echo on a chip

    NASA Astrophysics Data System (ADS)

    Moiseev, E. S.; Moiseev, S. A.

    2017-01-01

    We demonstrate that a photon echo can be implemented by all-optical means using an array of on-chip high-finesse ring cavities whose parameters are chirped in such a way as to support equidistant spectra of cavity modes. When launched into such a system, a classical or quantum optical signal—even a single-photon field—becomes distributed between individual cavities, giving rise to prominent coherence echo revivals at well-defined delay times, controlled by the chirp of cavity parameters. This effect enables long storage times for high-throughput broadband optical delay and quantum memory.

  4. Collision-induced stimulated photon echo in magnetic field

    NASA Astrophysics Data System (ADS)

    Reshetov, V. A.

    2015-12-01

    The action of the longitudinal magnetic field on the collision-induced stimulated photon echo formed on the transition with the angular momentum change {{J}a}=0\\to {{J}b}=1 is studied theoretically. It is shown that this action depends essentially on the sign of the difference in the orientation Γb(1) and alignment Γb(2) relaxation rates of the excited level b. If Γb(2)>Γb(1) , then the echo intensity in a weak magnetic field increases with the increase in the magnetic field strength, while in the alternative case Γb(2)<Γb(1) it decreases up to zero value. The formulae enabling the determination of the magnitude of the difference Γb(1)-Γb(2) from the experimental study of the oscillations of the echo intensity with the increase in the magnetic field strength are obtained.

  5. Photon echo with a few photons in two-level atoms

    NASA Astrophysics Data System (ADS)

    Bonarota, M.; Dajczgewand, J.; Louchet-Chauvet, A.; Le Gouët, J.-L.; Chanelière, T.

    2014-09-01

    To store and retrieve signals at the single photon level, various photon echo schemes have resorted to complex preparation steps involving ancillary shelving states in multi-level atoms. For the first time, we experimentally demonstrate photon echo operation at such a low signal intensity without any preparation step, which allows us to work with mere two-level atoms. This simplified approach relies on the so-coined ‘revival of silenced echo’ (ROSE) scheme. Low noise conditions are obtained by returning the atoms to the ground state before the echo emission. In the present paper we manage ROSE in photon counting conditions, showing that very strong control fields can be compatible with extremely weak signals, making ROSE consistent with quantum memory requirements.

  6. Photonic crystal fiber mapping using Brillouin echoes distributed sensing.

    PubMed

    Stiller, B; Foaleng, S M; Beugnot, J-C; Lee, M W; Delqué, M; Bouwmans, G; Kudlinski, A; Thévenaz, L; Maillotte, H; Sylvestre, T

    2010-09-13

    In this paper we investigate the effect of microstructure irregularities and applied strain on backward Brillouin scattering by comparing two photonic crystal fibers drawn with different parameters in order to minimize diameter and microstructure fluctuations. We fully characterize their Brillouin properties including the gain spectrum and the critical power. Using Brillouin echoes distributed sensing with a high spatial resolution of 30 cm we are able to map the Brillouin frequency shift along the fiber and get an accurate estimation of the microstructure longitudinal fluctuations. Our results reveal a clear-cut difference of longitudinal homogeneity between the two fibers.

  7. Time-domain Fresnel-to-Fraunhofer diffraction with photon echoes.

    PubMed

    Ménager, L; Lorgeré, I; Gouët, J L; Mohan, R K; Kröll, S

    1999-07-15

    A photon echo experiment in Tm(3+):YAG is reported that shows, for the first time to the authors' knowledge, the time-domain equivalent of the transition from near- to far-field diffraction, including Talbot self-imaging effects. The experiment demonstrates the huge dispersion capability of photon echoes and opens the way to further exploration of space-time duality.

  8. Photon echo spectroscopy reveals structure-dynamics relationships in carotenoids

    NASA Astrophysics Data System (ADS)

    Christensson, N.; Polivka, T.; Yartsev, A.; Pullerits, T.

    2009-06-01

    Based on simultaneous analysis of the frequency-resolved transient grating, peak shift, and echo width signals, we present a model for the third-order optical response of carotenoids including population dynamics and system-bath interactions. Our frequency-resolved photon echo experiments show that the model needs to incorporate the excited-state absorption from both the S2 and the S1 states. We apply our model to analyze the experimental results on astaxanthin and lycopene, aiming to elucidate the relation between structure and system-bath interactions. Our analysis allows us to relate structural motifs to changes in the energy-gap correlation functions. We find that the terminal rings of astaxanthin lead to increased coupling between slow molecular motions and the electronic transition. We also find evidence for stronger coupling to higher frequency overdamped modes in astaxanthin, pointing to the importance of the functional groups in providing coupling to fluctuations influencing the dynamics in the passage through the conical intersection governing the S2-S1 relaxation.

  9. Magnetoresponsive Photonic Microspheres with Structural Color Gradient.

    PubMed

    Lee, Seung Yeol; Choi, Jongkook; Jeong, Jong-Ryul; Shin, Jung H; Kim, Shin-Hyun

    2017-02-06

    Photonic Janus particles are created by alternately sputtering silica and titania on microspheres in order to obtain a structural color gradient. In addition, the microspheres are rendered magnetoresponsive. The Janus microspheres with optical and magnetic anisotropy enable on-demand control over orientation and structural color through manipulation of an external magnetic field, thereby being useful as active color pigments for reflection-mode displays.

  10. Biomimetic photonic materials with tunable structural colors.

    PubMed

    Xu, Jun; Guo, Zhiguang

    2013-09-15

    Nature is a huge gallery of art involving nearly perfect structures and forms over the millions of years developing. Inspiration from natural structures exhibiting structural colors is first discussed. We give some examples of natural one-, two-, and three-dimensional photonic structures. This review article presents a brief summary of recent progress on bio-inspired photonic materials with variable structural colors, including the different facile and efficient routes to construct the nano-architectures, and the development of the artificial variable structural color photonic materials. Besides the superior optical properties, the excellent functions such as robust mechanical strength, good wettability are also mentioned, as well as the technical importance in various applications. This review will provide significant insight into the fabrication, design and application of the structural color materials.

  11. Photon echo in exciton-plasmon nanomaterials: A time-dependent signature of strong coupling.

    PubMed

    Blake, Adam; Sukharev, Maxim

    2017-02-28

    We investigate the dynamics of the photon echo exhibited by exciton-plasmon systems under strong coupling conditions. Using a self-consistent model based on coupled Maxwell-Bloch equations, we investigate the femtosecond time dynamics of ensembles of interacting molecules optically coupled to surface plasmon supporting materials. It is shown that observed photon echoes under a two pulse pump-probe sequence are highly dependent on various material parameters such as molecular concentration and periodicity. Simulations of photon echoes in exciton-plasmon materials reveal a unique signature of the strong exciton-plasmon coupling, namely, a double-peak structure in spectra of recorded echo signals. This phenomenon is shown to be related to hybrid states (upper and lower polaritons) in exciton-plasmon systems under strong coupling conditions. It is also demonstrated that the double-peak echo is highly sensitive to mild deviations of the coupling from resonant conditions making it a great tool for ultrafast probes.

  12. Conditions for Using Stimulated Photon Echo to Record and Reproduce Information in Three-Level Systems

    NASA Astrophysics Data System (ADS)

    Nefediev, L. A.; Nizamova, E. I.

    2016-01-01

    The conditions for observing photon echo signals in crystals with excitation and detection in different resonant transitions with a single common energy level are studied. Uncorrelated inhomogeneous broadening in different resonance transitions is shown to influence the formation of stimulated photon echo in three-level systems. Lowering the sample temperature makes it possible to increase the relaxation time, which is used in experiments for observing photon echo. Uncorrelated inhomogeneous broadening in different resonance transitions is temperature independent and affects the intensity of the response at low temperatures, as well. Observation of stimulated photon echo in solid three-level samples requires a correct choice of the time interval between the first and second exciting pulses, but is not related to the magnitude of the irreversible transverse relaxation of the system.

  13. Two-frequency information recording in a three-level system using stimulated photon echo

    SciTech Connect

    Garnaeva, G I; Nefediev, L A; Akhmedshina, E N; Garnaev, R N

    2015-07-31

    The process of recording and reproducing information in a three-level system using stimulated photon echo is studied as a function of the amount of information embedded in the first and second two-frequency object laser pulses. It is shown that two-frequency information recording leads to an increase in the power of the stimulated photon echo response on one frequency transition and to its reduction on the other. (laser applications and other topics in quantum electronics)

  14. Butterfly wing color: A photonic crystal demonstration

    NASA Astrophysics Data System (ADS)

    Proietti Zaccaria, Remo

    2016-01-01

    We have theoretically modeled the optical behavior of a natural occurring photonic crystal, as defined by the geometrical characteristics of the Teinopalpus Imperialis butterfly. In particular, following a genetic algorithm approach, we demonstrate how its wings follow a triclinic crystal geometry with a tetrahedron unit base. By performing both photonic band analysis and transmission/reflection simulations, we are able to explain the characteristic colors emerging by the butterfly wings, thus confirming their crystal form.

  15. Echo

    NASA Technical Reports Server (NTRS)

    1961-01-01

    'William J. O'Sullivan, the father of the Echo balloon, was also the father of five children. ... The NASA public affairs office distributed copies of this family portrait to the news media along with stories about O'Sullivan's ingenious invention of the Echo balloon.' 'O'Sullivan became one of NASA's most highly publicized scientists. In December 1960, the U.S. Post Office Department issued a commemorative 4-cent stamp in honor of his beloved Echo balloon. For his concept of the inflatable space vehicle, NASA would award him one of its distinguished service medals, in addition to $5000 cash. In 1962, O'Sullivan would appear as a guest on the popular TV game show 'What's My Line?'; all four of the celebrity panelists correctly picked him from the lineup as the father of the Echo satelloons.'

  16. Influence of neighboring levels in three-pulse photon-echo processes

    SciTech Connect

    Villaeys, A. A.; Dappe, Y. J.; Liang, K. K.; Lin, S. H.

    2009-05-15

    It is the purpose of the present paper to study the dynamics underlying a three-pulse photon-echo process performed on a vibronic system coupled to non-Markovian baths, when a neighboring level enters into the global dynamical evolution because of broadband excitation required in these experiments. Particular emphasis is on the energy gap between the vibronic levels, but also on the fluctuation amplitudes and correlation times of their corresponding thermal baths. The photon-echo signal appears to be very sensitive to the additional interfering contributions introduced by the neighboring vibronic level. It is shown that these contributions associated to the pathways involving different vibronic states are modulated by their corresponding energy gap. As a consequence, these contributions to the integrated photon-echo signal strongly decrease for large energy gaps. Also, an oscillating behavior is observed on the time dependence of the photon-echo signal resulting from the summation of the contributions provided by the individual vibronic levels. Moreover, the influence of the non-Markovian character of the baths, accountable for inhomogeneous broadening, affects the amplitude and the time dependence of the photon-echo signal, as well as its dependence with the delay time of the laser pulses. Of course, for longer times a Markovian dynamical evolution is recovered.

  17. Collision-induced stimulated photon echo on the broad spectral line

    NASA Astrophysics Data System (ADS)

    Reshetov, V. A.

    2017-01-01

    The collision-induced stimulated photon echo formed on the broad spectral line on the transition with the angular momentum change {{J}a}=0\\to {{J}b}=1 is studied theoretically. The dependencies of the echo intensity on the areas of exciting pulses and on the strength of the external magnetic field under the conditions of experiments in ytterbium (174Yb) vapor are obtained. The ways to measure orientation and alignment relaxation rates of the excited atomic level are discussed.

  18. Femtosecond correlated photon echo in CdS crystal under two-photon excitation by two pairs of crossed laser beams

    NASA Astrophysics Data System (ADS)

    Samartsev, V. V.; Leontiev, A. V.; Mitrofanova, T. G.

    2015-07-01

    We consider the possibility of observing a femtosecond correlated photon echo (FCPE) under two-photon excitation of CdS crystal by two pairs of crossed laser beams. The peculiarities of FCPE signals and their possible applications are discussed.

  19. Two-dimensional photon echoes reveal non-Markovian energy transfer in an excitonic dimer

    NASA Astrophysics Data System (ADS)

    Duan, Hong-Guang; Frey, Moritz; Thorwart, Michael; Nalbach, Peter

    2016-11-01

    We show that strong non-Markovian effects can be revealed by the steady-state two-dimensional (2D) photon echo spectra at asymptotic waiting times. For this, we use a simple dimer toy model that is strongly coupled to a harmonic bath with parameters typical for photoactive biomolecules. We calculate the 2D photon echo spectra employing both the numerically exact hierarchy equation of motion and the quasiadiabatic path integral approach and compare these results with approximate results from a time-nonlocal quantum master equation approach. While the latter correctly reproduces the exact population dynamics at long times, it fails at the same time to correctly describe the 2D photon echo spectra at long waiting times. The differences show that non-Markovian effects are much more important for the steady-state 2D photon echoes than for the equilibrium populations. Thus, accurate theoretical descriptions of the energy transfer dynamics in biomolecular complexes have to be based on numerically exact simulations of the environmental fluctuations when nonlinear response functions are analyzed.

  20. Photon echoes from (In,Ga)As quantum dots embedded in a Tamm-plasmon microcavity

    NASA Astrophysics Data System (ADS)

    Salewski, M.; Poltavtsev, S. V.; Kapitonov, Yu. V.; Vondran, J.; Yakovlev, D. R.; Schneider, C.; Kamp, M.; Höfling, S.; Oulton, R.; Akimov, I. A.; Kavokin, A. V.; Bayer, M.

    2017-01-01

    We report on the coherent optical response from an ensemble of (In,Ga)As quantum dots (QDs) embedded in a planar Tamm-plasmon microcavity with a quality factor of approximately 100. Significant enhancement of the light-matter interaction is demonstrated under selective laser excitation of those quantum dots which are in resonance with the cavity mode. The enhancement is manifested through Rabi oscillations of the photon echo, demonstrating coherent control of excitons with picosecond pulses at intensity levels more than an order of magnitude smaller as compared with bare quantum dots. The decay of the photon echo transients is weakly changed by the resonator, indicating a small decrease of the coherence time T2 which we attribute to the interaction with the electron plasma in the metal layer located close (40 nm) to the QD layer. Simultaneously we see a reduction of the population lifetime T1, inferred from the stimulated photon echo, due to an enhancement of the spontaneous emission by a factor of 2, which is attributed to the Purcell effect, while nonradiative processes are negligible, as confirmed from time-resolved photoluminescence.

  1. Additive photonic colors in the Brazilian diamond weevil: entimus imperialis

    NASA Astrophysics Data System (ADS)

    Mouchet, S.; Vigneron, J.-P.; Colomer, J.-F.; Vandenbem, C.; Deparis, O.

    2012-10-01

    Structurally colored nano-architectures found in living organisms are complex optical materials, giving rise to multiscale visual effects. In arthropods, these structures often consist of porous biopolymers and form natural photonic crystals. A signature of the structural origin of coloration in insects is iridescence, i.e., color changes with the viewing angle. In the scales located on the elytra of the Brazilian weevil Entimus imperialis (Curculionidae), three-dimensional photonic crystals are observed. On one hand, each of them interacts independently with light, producing a single color which is observed by optical microscopy and ranges from blue to orange. On the other hand, the color perceived by the naked eye is due to multi-length-scale light effects involving different orientations of a single photonic crystal. This disorder in crystal orientations alters the light propagation in such a way that the crystal iridescence is removed. Entimus imperialis is therefore a remarkable example of additive photonic colors produced by a complex multi-scale organic architecture. In order to study this specific natural photonic structure, electron microscopy is used. The structure turns out to be formed of a single type of photonic crystal with different orientations within each scale on the elytra. Our modeling approach takes into account the disorder in the photonic crystals and explains why the structure displays bright colors at the level of individual scales and a non-iridescent green color in the far-field.

  2. Collision-induced stimulated photon echo at the transition 0-1 in ytterbium: application to depolarizing collisions

    NASA Astrophysics Data System (ADS)

    Rubtsova, N. N.; Gol'dort, V. G.; Khvorostov, E. B.; Kochubei, S. A.; Reshetov, V. A.

    2017-02-01

    A new idea based on the collision-induced stimulated photon echo in the presence of weak longitudinal magnetic field is applied to the depolarizing collisions research in a gaseous mixture of ytterbium vapour with xenon. Comparison of experimental data with theoretical prediction for the collision-induced stimulated photon echo in the weak magnetic field shows that the alignment decay rate of state 3P1 in 174Yb is higher than the orientation decay rate.

  3. The application of weak electric field pulses to measure the pseudo-Stark split by photon echo beating

    NASA Astrophysics Data System (ADS)

    Lisin, V. N.; Shegeda, A. M.; Samartsev, V. V.

    2016-07-01

    A novel scheme for determining the pseudo-Stark splitting of optical lines has been suggested and tested in experiment. The scheme allows one to observe the beating of a photon echo waveform under conditions of overlap in time between a weak electric pulse and its echo-pulse. The pseudo-Stark splitting is equal to the inverse average modulation period of the echo waveform. The photon echo beating of the R1-line in Ruby has been observed. The dependence of the inverse average modulation period of the echo waveform on the average value of the electric field over the optically excited volume has been found. The obtained values of the pseudo-Stark parameter are in good agreement with known literature data.

  4. Trapping photon-dressed Dirac electrons in a quantum dot studied by coherent two dimensional photon echo spectroscopy

    PubMed Central

    Roslyak, O.; Gumbs, Godfrey; Mukamel, S.

    2012-01-01

    We study the localization of dressed Dirac electrons in a cylindrical quantum dot (QD) formed on monolayer and bilayer graphene by spatially different potential profiles. Short lived excitonic states which are too broad to be resolved in linear spectroscopy are revealed by cross peaks in the photon-echo nonlinear technique. Signatures of the dynamic gap in the two-dimensional spectra are discussed. The effect of the Coulomb induced exciton-exciton scattering and the formation of biexciton molecules are demonstrated. PMID:22612079

  5. Velocity-changing collisional effects in nonlinear atomic spectroscopy and photon echo decay in gases

    NASA Technical Reports Server (NTRS)

    Herman, R. M.

    1983-01-01

    A general theory of atomic dipole coherence under the influence of collisional phase changes, inelastic effects and optically active atom velocity changes, including those due to anisotropic interactions is presented. Velocity change effects are obtained in closed form. Line shapes appear as convolutions of standard pressure broadening contours with velocity-change contours. Width and shift parameters for the He-broadened Na D lines at 2 m bar pressure, 380 K are calculated, as are He-induced photon echo decay rates for these lines. Overall agreement with xperiment is reasonably good.

  6. Anomalous decay of photon echo in a quantum dot ensemble in the strong excitation regime

    SciTech Connect

    Suemori, Ryosuke; Ishi-Hayase, Junko; Akahane, Kouichi; Yamamoto, Naokatsu

    2013-12-04

    We investigated the coherent dynamics of exciton ground-state transitions in an 150-layer-stacked strain-compensated InAs quantum dot ensemble using photon echo (PE) technique in the strong excitation regime. The time delay dependence of PE signal intensity shows a drastic change depending on the excitation intensity and the aperture position placed in front of a detector. Our results suggest that the excitation-intensity-dependent spatial distribution of PE signal intensity plays an important role in observing PE signal decay in the strong excitation regime.

  7. Monocycle and doublet pulses generation via photon echo in rare-earth-doped optical crystal

    NASA Astrophysics Data System (ADS)

    Huang, Kai; Zhang, Shuanggen; Ma, Xiurong; Hu, Minglie; Wang, Qingyue

    2016-12-01

    All-optical pulse generation opens up a field for ultrawideband (UWB) applications. However, controllable pulse width and pulse type are still challenging. Here, we present a theoretical model and stimulated results of monocycle and doublet waveforms generation using programmable optical photon echo progress. We synthesized instantaneously monocycle and doublet waveforms by adjustment of pulse width, pulse amplitude, pulse position, and time interval of subpulses. We verified the possible application of the proposed method to design U.S. Federal Communications Commission-compliant UWB waveforms, and therefore, it may provide an avenue for waveform generation.

  8. High resolution reversible color images on photonic crystal substrates.

    PubMed

    Kang, Pilgyu; Ogunbo, Samuel O; Erickson, David

    2011-08-16

    When light is incident on a crystalline structure with appropriate periodicity, some colors will be preferentially reflected (Joannopoulos, J. D.; Meade, R. D.; Winn, J. N. Photonic crystals: molding the flow of light; Princeton University Press: Princeton, NJ, 1995; p ix, 137 pp). These photonic crystals and the structural color they generate represent an interesting method for creating reflective displays and drawing devices, since they can achieve a continuous color response and do not require back lighting (Joannopoulos, J. D.; Villeneuve, P. R.; Fan, S. H. Photonic crystals: Putting a new twist on light. Nature 1997, 386, 143-149; Graham-Rowe, D. Tunable structural colour. Nat. Photonics 2009, 3, 551-553.; Arsenault, A. C.; Puzzo, D. P.; Manners, I.; Ozin, G. A. Photonic-crystal full-colour displays. Nat. Photonics 2007, 1, 468-472; Walish, J. J.; Kang, Y.; Mickiewicz, R. A.; Thomas, E. L. Bioinspired Electrochemically Tunable Block Copolymer Full Color Pixels. Adv. Mater.2009, 21, 3078). Here we demonstrate a technique for creating erasable, high-resolution, color images using otherwise transparent inks on self-assembled photonic crystal substrates (Fudouzi, H.; Xia, Y. N. Colloidal crystals with tunable colors and their use as photonic papers. Langmuir 2003, 19, 9653-9660). Using inkjet printing, we show the ability to infuse fine droplets of silicone oils into the crystal, locally swelling it and changing the reflected color (Sirringhaus, H.; Kawase, T.; Friend, R. H.; Shimoda, T.; Inbasekaran, M.; Wu, W.; Woo, E. P. High-resolution inkjet printing of all-polymer transistor circuits. Science 2000, 290, 2123-2126). Multicolor images with resolutions as high as 200 μm are obtained from oils of different molecular weights with the lighter oils being able to penetrate deeper, yielding larger red shifts. Erasing of images is done simply by adding a low vapor pressure oil which dissolves the image, returning the substrate to its original state.

  9. Photon echo under excitation of a medium by pulses consisting of an arbitrary number of oscillations

    NASA Astrophysics Data System (ADS)

    Znamenskii, N. V.; Sazonov, S. V.

    2008-03-01

    Echo responses of a three-level medium formed by the λ-scheme of quantum transitions under exposure to optical pulses consisting of an arbitrary number of oscillations have been studied theoretically. The cases of pulses consisting of few optical oscillations (for which the concept of an envelope cannot be used) and combinations of such pulses and quasi-monochromatic resonance signals have been considered. The approach used can be reduced to the renormalization of dipole moments of allowed quantum transitions through their multiplication by coefficients depending on the shape and duration of pump pulses and having absolute values in the range from zero (for nonresonance pulses) to unity (for resonance quasi-monochromatic pulses and broadband pulses consisting of few oscillations, whose spectrum covers the quantum transitions). A general equation has been proposed for the pulse area. In the limit of a large number of oscillations, it transforms into the well-known definition of the area of a quasi-monochromatic signal. The characteristics of primary and longlived photon echoes have been analyzed in detail. It has been shown that, when a medium is exposed to only pulses consisting of a few oscillations, three echo responses of both types can be principally generated at each frequency of the λ-scheme. Introduction of quasi-monochromatic pulses in pump pulse series decreases the number of echoes, and their qualitative character has a non-commutative property with respect to pulse permutation in a series. The extension of the proposed approach to more complex schemes of quantum transitions with the large number of quantum levels faces no principal difficulties.

  10. Dispersed three-pulse infrared photon echoes of nitrous oxide in water and octanol.

    PubMed

    Shattuck, J T; Schneck, J R; Chieffo, L R; Erramilli, S; Ziegler, L D

    2013-12-12

    Dispersed IR three-pulse photon echoes due to the antisymmetric (ν3) stretch mode of N2O dissolved in H2O and 1-octanol at room temperature are reported and analyzed. The experimentally determined transition frequency-frequency correlation function (FFCF) in these two solvents is explained in terms of inertial solvent contributions, hydrogen bond network fluctuations, and, for octanol, the motions of the alkyl chains. The H2O hydrogen bond fluctuations result in 1.5 ps FFCF decay, in agreement with relaxation rates determined from photon echo based measurements of other aqueous solutions including salt solutions. In octanol, hydrogen bond fluctuations decay on a slower time scale of 3.3 ps and alkyl chain motions result in an inhomogeneous broadening contribution to the ν3 absorption spectrum that decays on a 35 ps time scale. Rotational reorientation of N2O is nearly 3 times faster in octanol as compared to water. Although the vibrational ν3 N2O absorption line shapes in water and octanol are similar, the line widths result from different coherence loss mechanisms. A hot band contribution in the N2O in octanol solution is found to have a significant effect on the echo spectrum due to its correspondingly stronger transition moment than that of the fundamental transition. The dephasing dynamics of the N2O ν3 stretch mode is of interest as a probe in ultrafast studies of complex or nanoconfined systems with both hydrophobic and hydrophilic regions such as phospholipids, nucleic acids, and proteins. These results demonstrate the value of the N2O molecule to act as a reporter of equilibrium fluctuations in such complex systems particularly due to its solubility characteristics and long vibrational lifetime.

  11. Structural Color Patterns by Electrohydrodynamic Jet Printed Photonic Crystals.

    PubMed

    Ding, Haibo; Zhu, Cun; Tian, Lei; Liu, Cihui; Fu, Guangbin; Shang, Luoran; Gu, Zhongze

    2017-02-09

    In this work, we demonstrate the fabrication of photonic crystal patterns with controllable morphologies and structural colors utilizing electrohydrodynamic jet (E-jet) printing with colloidal crystal inks. The final shape of photonic crystal units is controlled by the applied voltage signal and wettability of the substrate. Optical properties of the structural color patterns are tuned by the self-assembly of the silica nanoparticle building blocks. Using this direct printing technique, it is feasible to print customized functional patterns composed of photonic crystal dots or photonic crystal lines according to relevant printing mode and predesigned tracks. This is the first report for E-jet printing with colloidal crystal inks. Our results exhibit promising applications in displays, biosensors, and other functional devices.

  12. Free-Standing Photonic Crystal Films with Gradient Structural Colors.

    PubMed

    Ding, Haibo; Liu, Cihui; Ye, Baofen; Fu, Fanfan; Wang, Huan; Zhao, Yuanjin; Gu, Zhongze

    2016-03-23

    Hydrogel colloidal crystal composite materials have a demonstrated value in responsive photonic crystals (PhCs) via controllable stimuli. Although they have been successfully exploited to generate a gradient of color distribution, the soft hydrogels have limitations in terms of stability and storage caused by dependence on environment. Here, we present a practical strategy to fabricate free-standing PhC films with a stable gradient of structural colors using binary polymer networks. A colloidal crystal hydrogel film was prepared for this purpose, with continuously varying photonic band gaps corresponding to the gradient of the press. Then, a second polymer network was used to lock the inside non-close-packed PhC structures and color distribution of the hydrogel film. It was demonstrated that our strategy could bring about a solution to the angle-dependent structural colors of the PhC films by coating the surface with special microstructures.

  13. Effect of pulse propagation on the two-dimensional photon echo spectrum of multilevel systems

    NASA Astrophysics Data System (ADS)

    Keusters, Dorine; Warren, Warren S.

    2003-08-01

    The effect of pulse propagation on the two-dimensional photon echo (2DPE) spectrum of multilevel systems is investigated using a perturbative method. At high optical densities (OD) peak profiles are broadened asymmetrically, in most cases more strongly along the ω2 direction than along the ω1 direction. The amount of broadening is determined both by the OD and by the dynamics of the system. In addition, especially if the different transitions in the system are of unequal strength, the relative intensity of the peaks changes with OD. But even if the transition strengths are the same, the behavior of the cross peaks is different from the diagonal peaks. Since peak shape and relative intensity are important parameters in the interpretation of 2DPE spectra, such OD effects should be taken into account.

  14. Access to long-term optical memories using photon echoes retrieved from semiconductor spins

    NASA Astrophysics Data System (ADS)

    Langer, L.; Poltavtsev, S. V.; Yugova, I. A.; Salewski, M.; Yakovlev, D. R.; Karczewski, G.; Wojtowicz, T.; Akimov, I. A.; Bayer, M.

    2014-11-01

    The ability to store optical information is important for both classical and quantum communication. Achieving this in a comprehensive manner (converting the optical field into material excitation, storing this excitation, and releasing it after a controllable time delay) is greatly complicated by the many, often conflicting, properties of the material. More specifically, optical resonances in semiconductor quantum structures with high oscillator strength are inevitably characterized by short excitation lifetimes (and, therefore, short optical memory). Here, we present a new experimental approach to stimulated photon echoes by transferring the information contained in the optical field into a spin system, where it is decoupled from the optical vacuum field and may persist much longer. We demonstrate this for an n-doped CdTe/(Cd,Mg)Te quantum well, the storage time of which could be increased by more than three orders of magnitude, from the picosecond range up to tens of nanoseconds.

  15. Two-dimensional infrared spectroscopy of peptides by phase-controlled femtosecond vibrational photon echoes

    PubMed Central

    Asplund, M. C.; Zanni, M. T.; Hochstrasser, R. M.

    2000-01-01

    Two-dimensional infrared spectra of peptides are introduced that are the direct analogues of two- and three-pulse multiple quantum NMR. Phase matching and heterodyning are used to isolate the phase and amplitudes of the electric fields of vibrational photon echoes as a function of multiple pulse delays. Structural information is made available on the time scale of a few picoseconds. Line narrowed spectra of acyl-proline-NH2 and cross peaks implying the coupling between its amide-I modes are obtained, as are the phases of the various contributions to the signals. Solvent-sensitive structural differences are seen for the dipeptide. The methods show great promise to measure structure changes in biology on a wide range of time scales. PMID:10890905

  16. Why the two-pulse photon echo is not a good quantum memory protocol

    SciTech Connect

    Ruggiero, Jerome; Le Goueet, Jean-Louis; Chaneliere, Thierry; Simon, Christoph

    2009-05-15

    We consider in this paper a two-pulse photon echo sequence in the prospect of quantum light storage. We analyze the conditions where quantum storage could be realistically performed. We simply and analytically calculate the efficiency in that limit, and clarify the role of the exactly {pi}-rephasing pulse in the sequence. Our physical interpretation of the process is well supported by its experimental implementation in a Tm{sup 3+}:yttrium aluminum garnet crystal thanks to an accurate control of the rephasing pulse area. We finally address independently the fundamental limitations of the quantum fidelity. Our work allows us to point out on one side the real drawbacks of this scheme for quantum storage and on the other side its specificities which can be a source of inspiration to conceive more promising procedures with rare-earth ion doped crystals.

  17. Information reproducibility in a stimulated photon-echo response at different orientations of external spatially inhomogeneous electric fields

    NASA Astrophysics Data System (ADS)

    Garnaeva, G. I.; Nefediev, L. A.; Khakimzyanova, E. I.; Nefedieva, K. L.

    2014-08-01

    We have studied the locking effect of photon-echo responses in a three-level system and the information reproducibility upon coding the information in the temporal shape of the object laser pulse. We have shown that these effects differ from their analogs in the two-level system.

  18. Access to long-term optical memories using photon echoes retrieved from electron spins in semiconductor quantum wells

    NASA Astrophysics Data System (ADS)

    Poltavtsev, S. V.; Langer, L.; Yugova, I. A.; Salewski, M.; Kapitonov, Y. V.; Yakovlev, D. R.; Karczewski, G.; Wojtowicz, T.; Akimov, I. A.; Bayer, M.

    2016-10-01

    We use spontaneous (two-pulse) and stimulated (three-pulse) photon echoes for studying the coherent evolution of optically excited ensemble of trions which are localized in semiconductor CdTe/CdMgTe quantum well. Application of transverse magnetic field leads to the Larmor precession of the resident electron spins, which shuffles optically induced polarization between optically accessible and inaccessible states. This results in several spectacular phenomena. First, magnetic field induces oscillations of spontaneous photon echo amplitude. Second, in three-pulse excitation scheme, the photon echo decay is extended by several orders of magnitude. In this study, short-lived optical excitation which is created by the first pulse is coherently transferred into a long-lived electron spin state using the second optical pulse. This coherent spin state of electron ensemble persists much longer than any optical excitation in the system, preserving information on initial optical field, which can be retrieved as a photon echo by means of third optical pulse.

  19. Photonic Crystal Structures with Tunable Structure Color as Colorimetric Sensors

    PubMed Central

    Wang, Hui; Zhang, Ke-Qin

    2013-01-01

    Colorimetric sensing, which transduces environmental changes into visible color changes, provides a simple yet powerful detection mechanism that is well-suited to the development of low-cost and low-power sensors. A new approach in colorimetric sensing exploits the structural color of photonic crystals (PCs) to create environmentally-influenced color-changeable materials. PCs are composed of periodic dielectrics or metallo-dielectric nanostructures that affect the propagation of electromagnetic waves (EM) by defining the allowed and forbidden photonic bands. Simultaneously, an amazing variety of naturally occurring biological systems exhibit iridescent color due to the presence of PC structures throughout multi-dimensional space. In particular, some kinds of the structural colors in living organisms can be reversibly changed in reaction to external stimuli. Based on the lessons learned from natural photonic structures, some specific examples of PCs-based colorimetric sensors are presented in detail to demonstrate their unprecedented potential in practical applications, such as the detections of temperature, pH, ionic species, solvents, vapor, humidity, pressure and biomolecules. The combination of the nanofabrication technique, useful design methodologies inspired by biological systems and colorimetric sensing will lead to substantial developments in low-cost, miniaturized and widely deployable optical sensors. PMID:23539027

  20. Photonic crystal structures with tunable structure color as colorimetric sensors.

    PubMed

    Wang, Hui; Zhang, Ke-Qin

    2013-03-28

    Colorimetric sensing, which transduces environmental changes into visible color changes, provides a simple yet powerful detection mechanism that is well-suited to the development of low-cost and low-power sensors. A new approach in colorimetric sensing exploits the structural color of photonic crystals (PCs) to create environmentally-influenced color-changeable materials. PCs are composed of periodic dielectrics or metallo-dielectric nanostructures that affect the propagation of electromagnetic waves (EM) by defining the allowed and forbidden photonic bands. Simultaneously, an amazing variety of naturally occurring biological systems exhibit iridescent color due to the presence of PC structures throughout multi-dimensional space. In particular, some kinds of the structural colors in living organisms can be reversibly changed in reaction to external stimuli. Based on the lessons learned from natural photonic structures, some specific examples of PCs-based colorimetric sensors are presented in detail to demonstrate their unprecedented potential in practical applications, such as the detections of temperature, pH, ionic species, solvents, vapor, humidity, pressure and biomolecules. The combination of the nanofabrication technique, useful design methodologies inspired by biological systems and colorimetric sensing will lead to substantial developments in low-cost, miniaturized and widely deployable optical sensors.

  1. Revealing invisible photonic printing: colorful pattern shown by water

    NASA Astrophysics Data System (ADS)

    Chen, C.; Dong, Z. Q.; Chen, Y.; Hu, X. B.; Zhu, X. R.; Zhu, Z. G.; Qian, S. H.; Shih, W. H.

    2017-01-01

    Patterning and displaying of photonic crystals are critical for building advanced photonic materials. We developed a monolayered colloidal crystal (MCC) based photonic material through a mask-assistant photo-polymerization process. Polystyrene (PS) nanoparticles were firstly assembled on the glass slide to form highly ordered MCC, this template is invisible and could diffract visible light when infiltrated by solvent. This reversibly displaying property was successfully maintained after the MCC was surrounding by a polymer layer via photo-polymerization, meanwhile a pattern could also be printed on the polymer with the help of a mask. Such photonic printing could be reversibly shown and hidden, revealing the colorful pattern was mainly due to the non-uniform cross-linking density of the polymer.

  2. Scalable Quantum Photonics with Single Color Centers in Silicon Carbide.

    PubMed

    Radulaski, Marina; Widmann, Matthias; Niethammer, Matthias; Zhang, Jingyuan Linda; Lee, Sang-Yun; Rendler, Torsten; Lagoudakis, Konstantinos G; Son, Nguyen Tien; Janzén, Erik; Ohshima, Takeshi; Wrachtrup, Jörg; Vučković, Jelena

    2017-02-24

    Silicon carbide is a promising platform for single photon sources, quantum bits (qubits), and nanoscale sensors based on individual color centers. Toward this goal, we develop a scalable array of nanopillars incorporating single silicon vacancy centers in 4H-SiC, readily available for efficient interfacing with free-space objective and lensed-fibers. A commercially obtained substrate is irradiated with 2 MeV electron beams to create vacancies. Subsequent lithographic process forms 800 nm tall nanopillars with 400-1400 nm diameters. We obtain high collection efficiency of up to 22 kcounts/s optical saturation rates from a single silicon vacancy center while preserving the single photon emission and the optically induced electron-spin polarization properties. Our study demonstrates silicon carbide as a readily available platform for scalable quantum photonics architecture relying on single photon sources and qubits.

  3. Collision-induced photon echo at the transition 0{r_reversible}1 in ytterbium vapor: Direct proof of depolarizing collision anisotropy

    SciTech Connect

    Rubtsova, N. N.; Gol'dort, V. G.; Ishchenko, V. N.; Khvorostov, E. B.; Kochubei, S. A.; Reshetov, V. A.; Yevseyev, I. V.

    2011-09-15

    A collision-induced photon echo arising at the transition 0{r_reversible}1 of ytterbium in the presence of heavy atomic buffer is investigated. Collision-induced echo signal appears in the case of mutually orthogonal linear polarizations of exciting pulses and it is absent without buffer. Collision-induced echo power grows with buffer pressure up to the maximum value and decays exponentially at further buffer pressure growth. Collision-induced echo power is essentially less than that of the ordinary echo generated by pulses with parallel polarizations in the same mixture, and its polarization is linear with the polarization vector directed along that of the first exciting pulse. All the properties of collision-induced photon echo are explained on the basis of collision relaxation dependence on the direction of active atom velocity.

  4. Transfer and retrieval of optical coherence to strain-compensated quantum dots using a heterodyne photon-echo technique

    SciTech Connect

    Suzuki, Kazumasa; Ishi-Hayase, Junko; Akahane, Kouichi; Yamamoto, Naokatsu

    2013-12-04

    We performed the proof-of-principle demonstration of photon-echo quantum memory using strain-compensated InAs quantum dot ensemble in the telecommunication wavelength range. We succeeded in transfer and retrieval of relative phase of a time-bin pulse with a high fidelity. Our demonstration suggests the possibility of realizing ultrabroadband, high time-bandwidth products, multi-mode quantum memory which is operable at telecommunication wavelength.

  5. The optimal conditions for the correlation of object pulse temporary form with the stimulated photon echo response in the presence of external spatial inhomogeneous electric fields

    NASA Astrophysics Data System (ADS)

    Garnaeva, G. I.; Nefediev, L. A.; Hakimzyanova, E. I.; Nefedieva, K. L.

    2014-08-01

    The influence of external spatially inhomogeneous electric fields on the reproducibility of the information and effectiveness of stimulated photon echo responses locking at different encoding information in the object laser pulses are investigated.

  6. Multispectral photon counting integral imaging system for color visualization of photon limited 3D scenes

    NASA Astrophysics Data System (ADS)

    Moon, Inkyu

    2014-06-01

    This paper provides an overview of a colorful photon-counting integral imaging system using Bayer elemental images for 3D visualization of photon limited scenes. The color image sensor with a format of Bayer color filter array, i.e., a red, a green, or a blue filter in a repeating pattern, captures elemental image set of a photon limited three-dimensional (3D) scene. It is assumed that the observed photon count in each channel (red, green or blue) follows Poisson statistics. The reconstruction of 3D scene with a format of Bayer is obtained by applying computational geometrical ray back propagation algorithm and parametric maximum likelihood estimator to the photon-limited Bayer elemental images. Finally, several standard demosaicing algorithms are applied in order to convert the 3D reconstruction with a Bayer format into a RGB per pixel format. Experimental results demonstrate that the gradient corrected linear interpolation technique achieves better performance in regard with acceptable PSNR and less computational complexity.

  7. Optical microscope using an interferometric source of two-color, two-beam entangled photons

    DOEpatents

    Dress, William B.; Kisner, Roger A.; Richards, Roger K.

    2004-07-13

    Systems and methods are described for an optical microscope using an interferometric source of multi-color, multi-beam entangled photons. A method includes: downconverting a beam of coherent energy to provide a beam of multi-color entangled photons; converging two spatially resolved portions of the beam of multi-color entangled photons into a converged multi-color entangled photon beam; transforming at least a portion of the converged multi-color entangled photon beam by interaction with a sample to generate an entangled photon specimen beam; and combining the entangled photon specimen beam with an entangled photon reference beam within a single beamsplitter. An apparatus includes: a multi-refringent device providing a beam of multi-color entangled photons; a condenser device optically coupled to the multi-refringent device, the condenser device converging two spatially resolved portions of the beam of multi-color entangled photons into a converged multi-color entangled photon beam; a beam probe director and specimen assembly optically coupled to the condenser device; and a beam splitter optically coupled to the beam probe director and specimen assembly, the beam splitter combining an entangled photon specimen beam from the beam probe director and specimen assembly with an entangled photon reference beam.

  8. Bimodal dynamics of mechanically constrained hydrogen bonds revealed by vibrational photon echoes

    NASA Astrophysics Data System (ADS)

    Bodis, Pavol; Yeremenko, Sergiy; Berná, José; Buma, Wybren J.; Leigh, David A.; Woutersen, Sander

    2011-04-01

    We have investigated the dynamics of the hydrogen bonds that connect the components of a [2]rotaxane in solution. In this rotaxane, the amide groups in the benzylic-amide macrocycle and the succinamide thread are connected by four equivalent N-HṡṡṡO=C hydrogen bonds. The fluctuations of these hydrogen bonds are mirrored by the frequency fluctuations of the NH-stretch modes, which are probed by means of three-pulse photon-echo peak shift spectroscopy. The hydrogen-bond fluctuations occur on three different time scales, with time constants of 0.1, 0.6, and ⩾200 ps. Comparing these three time scales to the ones found in liquid formamide, which contains the same hydrogen-bonded amide motif but without mechanical constraints, we find that the faster two components, which are associated with small-amplitude fluctuations in the strength of the N-HṡṡṡO=C hydrogen bonds, are very similar in the liquid and the rotaxane. However, the third component, which is associated with the breaking and subsequent reformation of hydrogen bonds, is found to be much slower in the rotaxane than in the liquid. It can be concluded that the mechanical bonding in a rotaxane does not influence the amplitude and time scale of the small-amplitude fluctuations of the hydrogen bonds, but strongly slows down the complete dissociation of these hydrogen bonds. This is probably because in a rotaxane breaking of the macrocycle-axle contacts is severely hindered by the mechanical constraints. The hydrogen-bond dynamics in rotaxane-based molecular machines can therefore be regarded as liquidlike on a time scale 1 ps and less, but structurally frozen on longer (up to at least 200 ps) time scales.

  9. Carotid endarterectomy versus stenting: Does the flow really change? An Echo-Color-Doppler analysis.

    PubMed

    Lucatelli, Pierleone; Fanelli, Fabrizio; Cirelli, Carlo; Sacconi, Beatrice; Anzidei, Michele; Montisci, Roberto; Sanfilippo, Roberto; Tamponi, Elisabetta; Catalano, Carlo; Saba, Luca

    2015-04-01

    To assess potential hemodynamic differences after carotid endarterectomy (CEA) and carotid artery stenting (CAS) and their eventual impact on clinical management. Between July 2012 and October 2013 two groups of 30 patients each referred for CEA or CAS were prospectively enrolled in two tertiary hospital care centers. Pre-procedural imaging assessment of carotid artery disease was performed with Echo-Color-Doppler (ECD) and computed tomography angiography (CTA). ECD was repeated within 24 h and 1, 6 and 12 months after surgical/endovascular procedures. Peak systolic velocity (PSV) and end diastolic velocity (EDV) were assessed at two standard sites: common carotid artery (CCA) and distal internal carotid artery (ICA). Twenty-four hours ECD findings highly differ between the two populations. CCA PSV in the CEA and CAS groups was respectively 44.88 ± 9.16 and 69.20 ± 20.04 cm/s (p = 0.002); CCA EDV was 16.11 ± 2.29 and 19.13 ± 6.42 cm/s (p = 0.065); ICA PSV was 46.11 ± 7.9 and 94.02 ± 57.7 cm/s (p = 0.0012); ICA EDV was 20.22 ± 4.33 and 30.47 ± 18.33 cm/s (p = 0.025). One month, 6 months and 1 year findings confirmed the different trend in the two cohorts; in particular, at 1 year: CCA PSV was 50.94 ± 12.44 and 60.59 ± 26.84 cm/s (p = 0.181); CCA EDV was 17.11 ± 3.46 and 19 ± 16.35 cm/s (p = 0.634); ICA PSV was 51.66 ± 10.1 and 70.86 ± 20.64 cm/s (p = 0.014); ICA EDV was 25.05 ± 8.65 and 32.66 ± 13 cm/s (p = 0.0609). ECD follow-up of patients undergone CEA or CAS may play a critical role in the clinical management. Strict surveillance of blood flow velocities allows reducing false positive re-stenosis diagnosis and choosing the best anti-aggregation therapies. Within the first month CEA patients benefit from a lower risk condition in comparison with CAS patients, due to a significantly faster PSV drop; moreover, long-term CCA PSV after CEA could be used as a surrogate marker of neointima formation.

  10. Color Fluctuations in High Energy Hadronand Photon-Nucleus Collisions

    NASA Astrophysics Data System (ADS)

    Frankfurt, Leonid; Strikman, Mark

    We explain that coherence of high energy QED and QCD processes implies existence of new kind of phenomena which are beyond a framework based on Regge poles (cuts). New phenomena emerge as the consequence of compositeness of the bound states and the Lorentz slowing down of interaction. We focus on the color fluctuations phenomena predicted earlier for pA collisions within QCD and recent evidence for this phenomenon from pA LHC run, significant modification of nuclear shadowing phenomenon in the diffractive photoproduction of vector mesons observed recently in the ultra peripheral collisions at LHC. We outlined briefly general properties of color fluctuations phenomena and perspectives of future studies of this phenomenon in electron (photon) collisions with nuclei.

  11. A Smart Colorful Supercapacitor with One Dimensional Photonic Crystals

    PubMed Central

    Liu, Cihui; Liu, Xing; Xuan, Hongyun; Ren, Jiaoyu; Ge, Liqin

    2015-01-01

    To meet the pressing demands for portable and flexible equipment in contemporary society, developing flexible, lightweight, and sustainable supercapacitor systems with large power densities, long cycle life, and ease of strongly required. However, estimating the state-of-charge of existing supercapacitors is difficult, and thus their service life is limited. In this study, we fabricate a flexible color indicative supercapacitor device with mesoporous polyaniline (mPANI)/Poly(N-Isopropyl acrylamide-Graphene Oxide-Acrylic Acid) (P(NiPPAm-GO-AA)) one dimensional photonic crystals (1DPCs) as the electrode material through a low-cost, eco-friendly, and scalable fabrication process. We found that the state-of-charge could be monitored by the structural color oscillation due to the change in the photonic band gap position of the 1DPCs. The flexible 1DPCs supercapacitor is thin at 3 mm and exhibits good specific capacitance of 22.6 F g−1 with retention of 91.1% after 3,000 cycles. This study shows the application of the 1DPCs supercapacitor as a visual ultrathin power source. The technology may find many applications in future wearable electronics. PMID:26689375

  12. A Smart Colorful Supercapacitor with One Dimensional Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Liu, Cihui; Liu, Xing; Xuan, Hongyun; Ren, Jiaoyu; Ge, Liqin

    2015-12-01

    To meet the pressing demands for portable and flexible equipment in contemporary society, developing flexible, lightweight, and sustainable supercapacitor systems with large power densities, long cycle life, and ease of strongly required. However, estimating the state-of-charge of existing supercapacitors is difficult, and thus their service life is limited. In this study, we fabricate a flexible color indicative supercapacitor device with mesoporous polyaniline (mPANI)/Poly(N-Isopropyl acrylamide-Graphene Oxide-Acrylic Acid) (P(NiPPAm-GO-AA)) one dimensional photonic crystals (1DPCs) as the electrode material through a low-cost, eco-friendly, and scalable fabrication process. We found that the state-of-charge could be monitored by the structural color oscillation due to the change in the photonic band gap position of the 1DPCs. The flexible 1DPCs supercapacitor is thin at 3 mm and exhibits good specific capacitance of 22.6 F g-1 with retention of 91.1% after 3,000 cycles. This study shows the application of the 1DPCs supercapacitor as a visual ultrathin power source. The technology may find many applications in future wearable electronics.

  13. Frequency-time correlation of inhomogeneous broadening in a three-level system and the stimulated photon echo locking effect

    NASA Astrophysics Data System (ADS)

    Nefed'ev, L. A.; Nizamova, E. I.; Garnaeva, G. I.

    2016-07-01

    The frequency-time correlation of inhomogeneous broadening on different transitions in a threelevel resonant medium in the presence of external spatially nonuniform electric fields is considered. It is shown that, under a certain relationship between the magnitudes of gradients of external nonuniform electric fields acting at different moments of time, it is possible to control the magnitude of the frequency-time correlation on different frequency transitions. An increase in the frequency-time correlation coefficient with certain strengths of external spatially nonuniform electric fields leads to the recovery of the phase memory of the system and an increase in the stimulated photon echo intensity.

  14. Interferometric source of multi-color, multi-beam entangled photons with mirror and mixer

    DOEpatents

    Dress, William B.; Kisner, Roger A.; Richards, Roger K.

    2004-06-01

    53 Systems and methods are described for an interferometric source of multi-color, multi-beam entangled photons. An apparatus includes: a multi-refringent device optically coupled to a source of coherent energy, the multi-refringent device providing a beam of multi-color entangled photons; a condenser device optically coupled to the multi-refringent device, the condenser device i) including a mirror and a mixer and ii) converging two spatially resolved portions of the beam of multi-color entangled photons into a converged multi-color entangled photon beam; a tunable phase adjuster optically coupled to the condenser device, the tunable phase adjuster changing a phase of at least a portion of the converged multi-color entangled photon beam to generate a first interferometeric multi-color entangled photon beam; and a beam splitter optically coupled to the condenser device, the beam splitter combining the first interferometeric multi-color entangled photon beam with a second interferometric multi-color entangled photon beam.

  15. Optimum conditions for correlation of the temporal shape of an object pulse with a stimulated photon echo response in inhomogeneous external electric fields

    NASA Astrophysics Data System (ADS)

    Nefediev, L. A.; Khakimzyanova, E. I.; Garnaeva, G. I.

    2013-12-01

    We have studied the information locking effect and the effect of correlation of the shape of an object laser pulse with the shape of a stimulated photon echo response in the presence of external spatially inhomogeneous electric fields. We have shown that, for the transition 3H4-3P0 in a LaF3:Pr3+ crystal, one can observe the effect of the correlation of the shape of an object laser pulse with the shape of a stimulated photon echo response and, depending on the scheme of the action of external spatially inhomogeneous electric fields, either the information locking effect or the information destroying effect.

  16. [Echo-color Doppler in the study of hypothyroidism in the adult].

    PubMed

    Lagalla, R; Caruso, G; Benza, I; Novara, V; Calliada, F

    1993-09-01

    Color-Doppler US was performed on 20 patients with sub-clinic hypothyroidism which had been confirmed by laboratory tests. In all cases, color-Doppler US showed increased parenchymal flow, whose semiology was similar to the one known as "thyroid inferno" and currently associated, in the literature, with diffuse hyperfunction conditions. Quantitative measurements yielded no further element for differential diagnosis, while showing high flow speeds which were similar to those in hyperfunction. On the basis of consequent physiopathologic considerations, hypervascularization, as observed in hypothyroidism, is likely to be referred to the hypertrophic action of TSH, which was reported as high in all patients. In conclusion, the color-Doppler "thyroid inferno" pattern, which has been to date considered as specific of thyroid hyperfunction, has lost part of its diagnostic specificity, and further investigation--e.g. hormonal titers, scintigraphy--is needed for an unquestionable diagnosis to be made.

  17. Vivid structural colors with low angle dependence from long-range ordered photonic crystal films.

    PubMed

    Su, Xin; Xia, Hongbo; Zhang, Shufen; Tang, Bingtao; Wu, Suli

    2017-03-02

    Structural colored materials have attracted increasing attention due to their vivid color effects and non-photobleaching characteristics. However, the angle dependence of these structural colors severely restricts their practical applications, for example, in display and sensing devices. Here, a new strategy for obtaining low angle dependent structural colors is demonstrated by fabricating long-range ordered photonic crystal films. By using spheres with high refractive indices as building blocks, the angle dependence of the obtained colors has been strongly suppressed. Green, golden yellow and red structural colored films with low angle dependence were obtained by using 145 nm, 165 nm and 187 nm Cu2O spheres as building blocks, respectively. SEM images confirmed the long-range highly ordered arrays of the Cu2O photonic crystal films. Reflectance spectra and digital photographs clearly demonstrate the low angle dependence of these structural colors, which is in sharp comparison with the case of polystyrene (PS) and SiO2 photonic crystal films. Furthermore, these structural colors are vivid with high color saturation, not only under black background, but also under white background and natural light without adding any light-absorbing agents. These low angle dependent structural colors endow Cu2O photonic crystal films with great potential in practical applications. Our findings may broaden the strategies for the design and fabrication of angle independent structural colored materials.

  18. Absence of red structural color in photonic glasses, bird feathers, and certain beetles

    NASA Astrophysics Data System (ADS)

    Magkiriadou, Sofia; Park, Jin-Gyu; Kim, Young-Seok; Manoharan, Vinothan N.

    2014-12-01

    Colloidal glasses, bird feathers, and beetle scales can all show structural colors arising from short-ranged spatial correlations between scattering centers. Unlike the structural colors arising from Bragg diffraction in ordered materials like opals, the colors of these photonic glasses are independent of orientation, owing to their disordered, isotropic microstructures. However, there are few examples of photonic glasses with angle-independent red colors in nature, and colloidal glasses with particle sizes chosen to yield structural colors in the red show weak color saturation. Using scattering theory, we show that the absence of angle-independent red color can be explained by the tendency of individual particles to backscatter light more strongly in the blue. We discuss how the backscattering resonances of individual particles arise from cavity-like modes and how they interact with the structural resonances to prevent red. Finally, we use the model to develop design rules for colloidal glasses with red, angle-independent structural colors.

  19. Absence of red structural color in photonic glasses, bird feathers, and certain beetles.

    PubMed

    Magkiriadou, Sofia; Park, Jin-Gyu; Kim, Young-Seok; Manoharan, Vinothan N

    2014-12-01

    Colloidal glasses, bird feathers, and beetle scales can all show structural colors arising from short-ranged spatial correlations between scattering centers. Unlike the structural colors arising from Bragg diffraction in ordered materials like opals, the colors of these photonic glasses are independent of orientation, owing to their disordered, isotropic microstructures. However, there are few examples of photonic glasses with angle-independent red colors in nature, and colloidal glasses with particle sizes chosen to yield structural colors in the red show weak color saturation. Using scattering theory, we show that the absence of angle-independent red color can be explained by the tendency of individual particles to backscatter light more strongly in the blue. We discuss how the backscattering resonances of individual particles arise from cavity-like modes and how they interact with the structural resonances to prevent red. Finally, we use the model to develop design rules for colloidal glasses with red, angle-independent structural colors.

  20. Parallel and Multivalued Logic by the Two-Dimensional Photon-Echo Response of a Rhodamine–DNA Complex

    PubMed Central

    2015-01-01

    Implementing parallel and multivalued logic operations at the molecular scale has the potential to improve the miniaturization and efficiency of a new generation of nanoscale computing devices. Two-dimensional photon-echo spectroscopy is capable of resolving dynamical pathways on electronic and vibrational molecular states. We experimentally demonstrate the implementation of molecular decision trees, logic operations where all possible values of inputs are processed in parallel and the outputs are read simultaneously, by probing the laser-induced dynamics of populations and coherences in a rhodamine dye mounted on a short DNA duplex. The inputs are provided by the bilinear interactions between the molecule and the laser pulses, and the output values are read from the two-dimensional molecular response at specific frequencies. Our results highlights how ultrafast dynamics between multiple molecular states induced by light–matter interactions can be used as an advantage for performing complex logic operations in parallel, operations that are faster than electrical switching. PMID:25984269

  1. Formation of Stimulated Photon Echo in Three-Level Systems and Recovery of Phase Memory by External Spatially Inhomogeneous Electric Fields

    NASA Astrophysics Data System (ADS)

    Nefediev, L. A.; Nizamova, E. I.

    2014-09-01

    The formation of stimulated photon echo is studied in three-level systems in the presence of external inhomogeneous electric fields. The ratio of the gradients of external spatially inhomogeneous electric fields required to recover the phase memory of the system is calculated. This ratio is found to correlate with the nonequidistance parameter of the spectrum of the system.

  2. Innovative Mobile Smart Photonic Dimensional, Color and Spectral Measurement Engineering

    NASA Astrophysics Data System (ADS)

    Hofmann, Dr Dietrich, Prof; Dittrich (B. Eng. , Paul-Gerald; Höfner (B. Eng. , Dieter; Kraus, Daniel

    2015-02-01

    Aim of the paper is the demonstration of a paradigm shift in dimensional, color and spectral measurements in industry, biology/medicine, farming/environmental protection and security, as well as in education and training: Measurement engineering and quality assurance become mobile, modular and smart. Smartpads, smartphones and smartwatches (smartcomps) in combination with innovative hardware apps (hwapps) and conventional software apps (swapps) are fundamental enablers for the transformation from conventional stationary working places towards innovative mobile working places with in-field measurements and point-of-care (POC) diagnostics. Furthermore mobile open online courses (MOOCs) are transforming the study habits. Practical examples for the application of innovative photonic micro dimensiometers, colorimeters and spectrometers will be given. The innovative approach opens so far untapped enormous markets for measurement science, engineering, applications, education and training. These innovative working conditions will be fast accepted due to their convenience, reliability and affordability. A highly visible advantage of smartcomps is the huge number of their real distribution, their worldwide connectivity via Internet and cloud services, the standardized interfaces like USB and HDMI and the experienced capabilities of their users for practical operations, obtained with their private smartcomps.

  3. Photonic color filters integrated with organic solar cells for energy harvesting.

    PubMed

    Park, Hui Joon; Xu, Ting; Lee, Jae Yong; Ledbetter, Abram; Guo, L Jay

    2011-09-27

    Color filters are indispensable in most color display applications. In most cases, they are chemical pigment-based filters, which produce a particular color by absorbing its complementary color, and the absorbed energy is totally wasted. If the absorbed and wasted energy can be utilized, e.g., to generate electricity, innovative energy-efficient electronic media could be envisioned. Here we show photonic nanostructures incorporated with photovoltaics capable of producing desirable colors in the visible band and utilize the absorbed light to simultaneously generate electrical powers. In contrast to the traditional colorant-based filters, these devices offer great advantages for electro-optic applications.

  4. Photon harvesting, coloring and polarizing in photovoltaic cell integrated color filters: efficient energy routing strategies for power-saving displays.

    PubMed

    Wen, Long; Chen, Qin; Song, Shichao; Yu, Yan; Jin, Lin; Hu, Xin

    2015-07-03

    We describe the integral electro-optical strategies that combine the functionalities of photovoltaic (PV) electricity generation and color filtering as well as polarizing to realize more efficient energy routing in display technology. Unlike the conventional pigment-based filters and polarizers, which absorb substantial amounts of unwanted spectral components and dissipate them in the form of heat, we propose converting the energy of those photons into electricity by constructing PV cell-integrated color filters based on a selectively transmitting aluminum (Al) rear electrode perforated with nanoholes (NHs). Combining with a dielectric-metal-dielectric (DMD) front electrode, the devices were optimized to enable efficient cavity-enhanced photon recycling in the PV functional layers. We perform a comprehensive theoretical and numerical analysis to explore the extraordinary optical transmission (EOT) through the Al NHs and identify basic design rules for achieving structural coloring or polarizing in our PV color filters. We show that the addition of thin photoactive polymer layers on the symmetrically configured Al NH electrode narrows the bandwidth of the EOT-assisted high-pass light filtering due to the strongly damped anti-symmetric coupling of the surface modes excited on the front and rear surface of the Al NHs, which facilitates the whole visible coloring with relatively high purity for the devices. By engineering the cut-off characteristics of the plasmonic waveguide mode supported by the circular or ellipsoidal Al NHs, beyond the photon recycling capacity, PV color filters and PV polarizing color filters that allow polarization-insensitive and strong polarization-anisotropic color filtering were demonstrated. The findings presented here may shed some light on expanding the utilization of PV electricity generation across new-generation energy-saving electrical display devices.

  5. Photon harvesting, coloring and polarizing in photovoltaic cell integrated color filters: efficient energy routing strategies for power-saving displays

    NASA Astrophysics Data System (ADS)

    Wen, Long; Chen, Qin; Song, Shichao; Yu, Yan; Jin, Lin; Hu, Xin

    2015-07-01

    We describe the integral electro-optical strategies that combine the functionalities of photovoltaic (PV) electricity generation and color filtering as well as polarizing to realize more efficient energy routing in display technology. Unlike the conventional pigment-based filters and polarizers, which absorb substantial amounts of unwanted spectral components and dissipate them in the form of heat, we propose converting the energy of those photons into electricity by constructing PV cell-integrated color filters based on a selectively transmitting aluminum (Al) rear electrode perforated with nanoholes (NHs). Combining with a dielectric-metal-dielectric (DMD) front electrode, the devices were optimized to enable efficient cavity-enhanced photon recycling in the PV functional layers. We perform a comprehensive theoretical and numerical analysis to explore the extraordinary optical transmission (EOT) through the Al NHs and identify basic design rules for achieving structural coloring or polarizing in our PV color filters. We show that the addition of thin photoactive polymer layers on the symmetrically configured Al NH electrode narrows the bandwidth of the EOT-assisted high-pass light filtering due to the strongly damped anti-symmetric coupling of the surface modes excited on the front and rear surface of the Al NHs, which facilitates the whole visible coloring with relatively high purity for the devices. By engineering the cut-off characteristics of the plasmonic waveguide mode supported by the circular or ellipsoidal Al NHs, beyond the photon recycling capacity, PV color filters and PV polarizing color filters that allow polarization-insensitive and strong polarization-anisotropic color filtering were demonstrated. The findings presented here may shed some light on expanding the utilization of PV electricity generation across new-generation energy-saving electrical display devices.

  6. Detection of dark states in two-dimensional electronic photon-echo signals via ground-state coherence

    SciTech Connect

    Egorova, Dassia

    2015-06-07

    Several recent experiments report on possibility of dark-state detection by means of so called beating maps of two-dimensional photon-echo spectroscopy [Ostroumov et al., Science 340, 52 (2013); Bakulin et al., Ultrafast Phenomena XIX (Springer International Publishing, 2015)]. The main idea of this detection scheme is to use coherence induced upon the laser excitation as a very sensitive probe. In this study, we investigate the performance of ground-state coherence in the detection of dark electronic states. For this purpose, we simulate beating maps of several models where the excited-state coherence can be hardly detected and is assumed not to contribute to the beating maps. The models represent strongly coupled electron-nuclear dynamics involving avoided crossings and conical intersections. In all the models, the initially populated optically accessible excited state decays to a lower-lying dark state within few hundreds femtoseconds. We address the role of Raman modes and of interstate-coupling nature. Our findings suggest that the presence of low-frequency Raman active modes significantly increases the chances for detection of dark states populated via avoided crossings, whereas conical intersections represent a more challenging task.

  7. Two-dimensional photon-echo spectroscopy at a conical intersection: A two-mode pyrazine model with dissipation

    NASA Astrophysics Data System (ADS)

    Sala, Matthieu; Egorova, Dassia

    2016-12-01

    The multi-dimensional electronic spectroscopy of ultrafast nuclear dynamics at conical intersections (CI) is an emerging field of investigation, which profits also from the recent extension of the techniques to the UV domain. We present a detailed computational study of oscillatory signatures in two-dimensional (2D) photon-echo spectroscopy (also known as 2D electronic spectroscopy, 2DES) for the two-mode pyrazine model with dissipation. Conventional 2D signals as well as the resulting beating maps are considered. Although of a reduced character, the model captures quite well all the main signatures of the excited-state dynamics of the molecule. Due to the ultrafast relaxation via the CI and no excited-state absorption from the low-lying dark state, the oscillatory components of the signal are found to be predominantly determined by the ground state bleach contribution. They reflect, therefore, the ground-state vibrational coherence induced in the Raman active mode. Beating maps provide a way to experimentally differentiate between ground state bleach and stimulated emission oscillatory components. The ultrafast decay of the latter constitutes a clear indirect signature of the CI. In the considered model, because of the sign properties of the involved transition dipole moments, the dominance of the ground-state coherence leads to anti-correlated oscillations of cross peaks located at symmetric positions with respect to the main diagonal.

  8. Tunable structural color in organisms and photonic materials for design of bioinspired materials.

    PubMed

    Fudouzi, Hiroshi

    2011-12-01

    In this paper, the key topics of tunable structural color in biology and material science are overviewed. Color in biology is considered for selected groups of tropical fish, octopus, squid and beetle. It is caused by nanoplates in iridophores and varies with their spacing, tilting angle and refractive index. These examples may provide valuable hints for the bioinspired design of photonic materials. 1D multilayer films and 3D colloidal crystals with tunable structural color are overviewed from the viewpoint of advanced materials. The tunability of structural color by swelling and strain is demonstrated on an example of opal composites.

  9. Tunable structural color in organisms and photonic materials for design of bioinspired materials

    NASA Astrophysics Data System (ADS)

    Fudouzi, Hiroshi

    2011-12-01

    In this paper, the key topics of tunable structural color in biology and material science are overviewed. Color in biology is considered for selected groups of tropical fish, octopus, squid and beetle. It is caused by nanoplates in iridophores and varies with their spacing, tilting angle and refractive index. These examples may provide valuable hints for the bioinspired design of photonic materials. 1D multilayer films and 3D colloidal crystals with tunable structural color are overviewed from the viewpoint of advanced materials. The tunability of structural color by swelling and strain is demonstrated on an example of opal composites.

  10. Tunable structural color in organisms and photonic materials for design of bioinspired materials

    PubMed Central

    Fudouzi, Hiroshi

    2011-01-01

    In this paper, the key topics of tunable structural color in biology and material science are overviewed. Color in biology is considered for selected groups of tropical fish, octopus, squid and beetle. It is caused by nanoplates in iridophores and varies with their spacing, tilting angle and refractive index. These examples may provide valuable hints for the bioinspired design of photonic materials. 1D multilayer films and 3D colloidal crystals with tunable structural color are overviewed from the viewpoint of advanced materials. The tunability of structural color by swelling and strain is demonstrated on an example of opal composites. PMID:27877454

  11. Micro-pixelation and color mixing in biological photonic structures (presentation video)

    NASA Astrophysics Data System (ADS)

    Bartl, Michael H.; Nagi, Ramneet K.

    2014-03-01

    The world of insects displays myriad hues of coloration effects produced by elaborate nano-scale architectures built into wings and exoskeleton. For example, we have recently found many weevils possess photonic architectures with cubic lattices. In this talk, we will present high-resolution three-dimensional reconstructions of weevil photonic structures with diamond and gyroid lattices. Moreover, by reconstructing entire scales we found arrays of single-crystalline domains, each oriented such that only selected crystal faces are visible to an observer. This pixel-like arrangement is key to the angle-independent coloration typical of weevils—a strategy that could enable a new generation of coating technologies.

  12. Simulations of the infrared, Raman, and 2D-IR photon echo spectra of water in nanoscale silica pores

    SciTech Connect

    Burris, Paul C.; Laage, Damien; Thompson, Ward H.

    2016-05-20

    Vibrational spectroscopy is frequently used to characterize nanoconfined liquids and probe the effect of the confining framework on the liquid structure and dynamics relative to the corresponding bulk fluid. However, it is still unclear what molecular-level information can be obtained from such measurements. In this Paper, we address this question by using molecular dynamics (MD) simulations to reproduce the linear infrared (IR), Raman, and two-dimensional IR (2D-IR) photon echo spectra for water confined within hydrophilic (hydroxyl-terminated) silica mesopores. To simplify the spectra the OH stretching region of isotopically dilute HOD in D2O is considered. An empirical mapping approach is used to obtain the OH vibrational frequencies, transition dipoles, and transition polarizabilities from the MD simulations. The simulated linear IR and Raman spectra are in good general agreement with measured spectra of water in mesoporous silica reported in the literature. The key effect of confinement on the water spectrum is a vibrational blueshift for OH groups that are closest to the pore interface. The blueshift can be attributed to the weaker hydrogen bonds (H-bonds) formed between the OH groups and silica oxygen acceptors. Non-Condon effects greatly diminish the contribution of these OH moieties to the linear IR spectrum, but these weaker H-bonds are readily apparent in the Raman spectrum. The 2D-IR spectra have not yet been measured and thus the present results represent a prediction. Lastly, the simulated spectra indicate that it should be possible to probe the slower spectral diffusion of confined water compared to the bulk liquid by analysis of the 2D-IR spectra.

  13. Simulations of the infrared, Raman, and 2D-IR photon echo spectra of water in nanoscale silica pores.

    PubMed

    Burris, Paul C; Laage, Damien; Thompson, Ward H

    2016-05-21

    Vibrational spectroscopy is frequently used to characterize nanoconfined liquids and probe the effect of the confining framework on the liquid structure and dynamics relative to the corresponding bulk fluid. However, it is still unclear what molecular-level information can be obtained from such measurements. In this paper, we address this question by using molecular dynamics (MD) simulations to reproduce the linear infrared (IR), Raman, and two-dimensional IR (2D-IR) photon echo spectra for water confined within hydrophilic (hydroxyl-terminated) silica mesopores. To simplify the spectra the OH stretching region of isotopically dilute HOD in D2O is considered. An empirical mapping approach is used to obtain the OH vibrational frequencies, transition dipoles, and transition polarizabilities from the MD simulations. The simulated linear IR and Raman spectra are in good general agreement with measured spectra of water in mesoporous silica reported in the literature. The key effect of confinement on the water spectrum is a vibrational blueshift for OH groups that are closest to the pore interface. The blueshift can be attributed to the weaker hydrogen bonds (H-bonds) formed between the OH groups and silica oxygen acceptors. Non-Condon effects greatly diminish the contribution of these OH moieties to the linear IR spectrum, but these weaker H-bonds are readily apparent in the Raman spectrum. The 2D-IR spectra have not yet been measured and thus the present results represent a prediction. The simulated spectra indicates that it should be possible to probe the slower spectral diffusion of confined water compared to the bulk liquid by analysis of the 2D-IR spectra.

  14. Simulations of the infrared, Raman, and 2D-IR photon echo spectra of water in nanoscale silica pores

    DOE PAGES

    Burris, Paul C.; Laage, Damien; Thompson, Ward H.

    2016-05-20

    Vibrational spectroscopy is frequently used to characterize nanoconfined liquids and probe the effect of the confining framework on the liquid structure and dynamics relative to the corresponding bulk fluid. However, it is still unclear what molecular-level information can be obtained from such measurements. In this Paper, we address this question by using molecular dynamics (MD) simulations to reproduce the linear infrared (IR), Raman, and two-dimensional IR (2D-IR) photon echo spectra for water confined within hydrophilic (hydroxyl-terminated) silica mesopores. To simplify the spectra the OH stretching region of isotopically dilute HOD in D2O is considered. An empirical mapping approach is usedmore » to obtain the OH vibrational frequencies, transition dipoles, and transition polarizabilities from the MD simulations. The simulated linear IR and Raman spectra are in good general agreement with measured spectra of water in mesoporous silica reported in the literature. The key effect of confinement on the water spectrum is a vibrational blueshift for OH groups that are closest to the pore interface. The blueshift can be attributed to the weaker hydrogen bonds (H-bonds) formed between the OH groups and silica oxygen acceptors. Non-Condon effects greatly diminish the contribution of these OH moieties to the linear IR spectrum, but these weaker H-bonds are readily apparent in the Raman spectrum. The 2D-IR spectra have not yet been measured and thus the present results represent a prediction. Lastly, the simulated spectra indicate that it should be possible to probe the slower spectral diffusion of confined water compared to the bulk liquid by analysis of the 2D-IR spectra.« less

  15. Echoes in Space and Time

    NASA Astrophysics Data System (ADS)

    Lin, Kang; Lu, Peifen; Ma, Junyang; Gong, Xiaochun; Song, Qiying; Ji, Qinying; Zhang, Wenbin; Zeng, Heping; Wu, Jian; Karras, Gabriel; Siour, Guillaume; Hartmann, Jean-Michel; Faucher, Olivier; Gershnabel, Erez; Prior, Yehiam; Averbukh, Ilya Sh.

    2016-10-01

    Echo in mountains is a well-known phenomenon, where an acoustic pulse is mirrored by the rocks, often with reverberating recurrences. For spin echoes in magnetic resonance and photon echoes in atomic and molecular systems, the role of the mirror is played by a second, time-delayed pulse that is able to reverse the flow of time and recreate the original impulsive event. Recently, alignment and orientation echoes were discussed in terms of rotational-phase-space filamentation, and they were optically observed in laser-excited molecular gases. Here, we observe hitherto unreported fractional echoes of high order, spatially rotated echoes, and the counterintuitive imaginary echoes at negative times. Coincidence Coulomb explosion imaging is used for a direct spatiotemporal analysis of various molecular alignment echoes, and the implications to echo phenomena in other fields of physics are discussed.

  16. Tuning the Structural Color of a 2D Photonic Crystal Using a Bowl-like Nanostructure.

    PubMed

    Umh, Ha Nee; Yu, Sungju; Kim, Yong Hwa; Lee, Su Young; Yi, Jongheop

    2016-06-22

    Structural colors of the ordered photonic nanostructures are widely used as an effective platform for manipulating the propagation of light. Although several approaches have been explored in attempts to mimic the structural colors, improving the reproducibility, mechanical stability, and the economic feasibility of sophisticated photonic crystals prepared by complicated processes continues to pose a challenge. In this study, we report on an alternative, simple method for fabricating a tunable photonic crystal at room temperature. A bowl-like nanostructure of TiO2 was periodically arranged on a thin Ti sheet through a two-step anodization process where its diameters were systemically controlled by changing the applied voltage. Consequently, they displayed a broad color distribution, ranging from red to indigo, and the principal reason for color generation followed the Bragg diffraction theory. This noncolorant method was capable of reproducing a Mondrian painting on a centimeter scale without the need to employ complex architectures, where the generated structural colors were highly stable under mechanical or chemical influence. Such a color printing technique represents a potentially promising platform for practical applications for anticounterfeit trademarks, wearable sensors, and displays.

  17. Full-Color Biomimetic Photonic Materials with Iridescent and Non-Iridescent Structural Colors

    NASA Astrophysics Data System (ADS)

    Kawamura, Ayaka; Kohri, Michinari; Morimoto, Gen; Nannichi, Yuri; Taniguchi, Tatsuo; Kishikawa, Keiki

    2016-09-01

    The beautiful structural colors in bird feathers are some of the brightest colors in nature, and some of these colors are created by arrays of melanin granules that act as both structural colors and scattering absorbers. Inspired by the color of bird feathers, high-visibility structural colors have been created by altering four variables: size, blackness, refractive index, and arrangement of the nano-elements. To control these four variables, we developed a facile method for the preparation of biomimetic core-shell particles with melanin-like polydopamine (PDA) shell layers. The size of the core-shell particles was controlled by adjusting the core polystyrene (PSt) particles’ diameter and the PDA shell thicknesses. The blackness and refractive index of the colloidal particles could be adjusted by controlling the thickness of the PDA shell. The arrangement of the particles was controlled by adjusting the surface roughness of the core-shell particles. This method enabled the production of both iridescent and non-iridescent structural colors from only one component. This simple and novel process of using core-shell particles containing PDA shell layers can be used in basic research on structural colors in nature and their practical applications.

  18. Full-Color Biomimetic Photonic Materials with Iridescent and Non-Iridescent Structural Colors

    PubMed Central

    Kawamura, Ayaka; Kohri, Michinari; Morimoto, Gen; Nannichi, Yuri; Taniguchi, Tatsuo; Kishikawa, Keiki

    2016-01-01

    The beautiful structural colors in bird feathers are some of the brightest colors in nature, and some of these colors are created by arrays of melanin granules that act as both structural colors and scattering absorbers. Inspired by the color of bird feathers, high-visibility structural colors have been created by altering four variables: size, blackness, refractive index, and arrangement of the nano-elements. To control these four variables, we developed a facile method for the preparation of biomimetic core-shell particles with melanin-like polydopamine (PDA) shell layers. The size of the core-shell particles was controlled by adjusting the core polystyrene (PSt) particles’ diameter and the PDA shell thicknesses. The blackness and refractive index of the colloidal particles could be adjusted by controlling the thickness of the PDA shell. The arrangement of the particles was controlled by adjusting the surface roughness of the core-shell particles. This method enabled the production of both iridescent and non-iridescent structural colors from only one component. This simple and novel process of using core-shell particles containing PDA shell layers can be used in basic research on structural colors in nature and their practical applications. PMID:27658446

  19. Full-Color Biomimetic Photonic Materials with Iridescent and Non-Iridescent Structural Colors.

    PubMed

    Kawamura, Ayaka; Kohri, Michinari; Morimoto, Gen; Nannichi, Yuri; Taniguchi, Tatsuo; Kishikawa, Keiki

    2016-09-23

    The beautiful structural colors in bird feathers are some of the brightest colors in nature, and some of these colors are created by arrays of melanin granules that act as both structural colors and scattering absorbers. Inspired by the color of bird feathers, high-visibility structural colors have been created by altering four variables: size, blackness, refractive index, and arrangement of the nano-elements. To control these four variables, we developed a facile method for the preparation of biomimetic core-shell particles with melanin-like polydopamine (PDA) shell layers. The size of the core-shell particles was controlled by adjusting the core polystyrene (PSt) particles' diameter and the PDA shell thicknesses. The blackness and refractive index of the colloidal particles could be adjusted by controlling the thickness of the PDA shell. The arrangement of the particles was controlled by adjusting the surface roughness of the core-shell particles. This method enabled the production of both iridescent and non-iridescent structural colors from only one component. This simple and novel process of using core-shell particles containing PDA shell layers can be used in basic research on structural colors in nature and their practical applications.

  20. Definition of Shifts of Optical Transitions Frequencies due to Pulse Perturbation Action by the Photon Echo Signal Form

    NASA Astrophysics Data System (ADS)

    Lisin, V. N.; Shegeda, A. M.; Samartsev, V. V.

    2015-09-01

    A relative phase shift between the different groups of excited dipoles, which appears as result of its frequency splitting due to action of a pulse of electric or magnetic fields, depends on a time, if the pulse overlaps in time with echo-pulse. As а consequence, the echo waveform is changed. The echo time form is modulated. The inverse modulation period well enough approximates Zeeman and pseudo-Stark splitting in the cases of magnetic and, therefore, electrical fields. Thus the g-factors of ground 4I15/2 and excited 4F9/2 optical states of Er3+ ion in LuLiF4 and YLiF4 have been measured and pseudo-Stark shift of R1 line in ruby has been determined.

  1. Color image authentication scheme via multispectral photon-counting double random phase encoding

    NASA Astrophysics Data System (ADS)

    Moon, Inkyu

    2015-05-01

    In this paper, we present an overview of a color image authentication scheme via multispectral photon-counting (MPCI) double random phase encoding (DRPE). The MPCI makes image sparse distributed and DRPE lets image be stationary white noise which make intruder attacks difficult. In this method, the original RGB image is down-sampled into Bayer image and then be encrypted with DRPE. The encrypted image is photon-counted and transmitted on internet channel. For image authentication, the decrypted Bayer image is interpolated into RBC image with demosaicing algorithm. Experimental results show that the decrypted image is not visually recognized under low light level but can be verified with nonlinear correlation algorithm.

  2. Modeling of a structural coloration of a photonic-crystal fiber

    NASA Astrophysics Data System (ADS)

    Sotsky, A. B.; Bel'skaya, O. A.; Sotskaya, L. I.

    2015-05-01

    Using a method that is based on the application of the Green's theorem and the addition theorem of Graph's cylinder functions, we have obtained a solution of a two-dimensional problem on lateral light diffraction by a photonic-crystal fiber that is formed by a finite number of parallel air channels in a bounded slab. We have investigated scattering cross-section spectra of hexagonally symmetric photonic-crystal fibers. It has been found that these fibers may have a structural coloration, which changes upon their extension.

  3. Nondestructive inspection of explosive materials using linearly polarized two-colored photon beam

    NASA Astrophysics Data System (ADS)

    Toyokawa, H.; Hayakawa, T.; Shizuma, T.; Hajima, R.; Masuda, K.; Ohgaki, H.

    2011-10-01

    A nondestructive inspection method for screening explosive materials that are hidden in passenger vehicles, trucks, and cargo containers with radiation shielding was presented. The method was examined experimentally using linearly polarized two-colored photon beam. A sample object was irradiated with the photon beam, followed by an emission of gamma-rays in nuclear resonance fluorescence. The gamma-rays from oxygen and nitrogen emitted through nuclear resonance fluorescence were measured using high-purity germanium detectors. We were able to evaluate the element concentration ratio.

  4. FIFTH SEMINAR IN MEMORY OF D.N. KLYSHKO: Anti-Stokes femtosecond photon echo in a polymer film

    NASA Astrophysics Data System (ADS)

    Petrushkin, S. V.; Samartsev, V. V.

    2007-12-01

    An anti-Stokes model is proposed which explains the room-temperature blue shift of the echo-signal spectrum compared to the spectrum of exciting femtosecond pulses in a polymer film doped with dye molecules. The possibility of realising the anti-Stokes regime of coherent laser cooling of such films is analysed.

  5. Spatially graded TiO₂-SiO₂ Bragg reflector with rainbow-colored photonic band gap.

    PubMed

    Singh, Dhruv Pratap; Lee, Seung Hee; Choi, Il Yong; Kim, Jong Kyu

    2015-06-29

    A simple single-step method to fabricate spatially graded TiO2-SiO2 Bragg stack with rainbow colored photonic band gap is presented. The gradation in thickness of the Bragg stack was accomplished with a modified glancing angle deposition (GLAD) technique with dynamic shadow enabled by a block attached to one edge of the rotating substrate. A linear gradation in thickness over a distance of about 17 mm resulted in a brilliant colorful rainbow pattern. Interestingly, the photonic band gap position can be changed across the whole visible wavelength range by linearly translating the graded Bragg stack over a large area substrate. The spatially graded Bragg stack may find potential applications in the tunable optical devices, such as optical filters, reflection gratings, and lasers.

  6. Photonic band gap effect and structural color from silver nanoparticle gelatin emulsion.

    PubMed

    Kok, Mang Hin; Ma, Rui; Lee, Jeffrey Chi Wai; Tam, Wing Yim; Chan, C T; Sheng, Ping; Cheah, Kok Wai

    2005-10-01

    We have fabricated planar structures of silver nanoparticles in monochromatic gelatin emulsion with a continuous spacing ranging from 0.15-0.40 micron using a two-beam interference of a single laser source. Our planar holograms display a colorful "rainbow" pattern and photonic bandgaps covering the visible and IR ranges. We model the planar silver nanoparticle-gelatin composite system using an effective medium approach and good agreement is obtained between theory and experiment.

  7. Inkjet Printing Based Mono-layered Photonic Crystal Patterning for Anti-counterfeiting Structural Colors

    PubMed Central

    Nam, Hyunmoon; Song, Kyungjun; Ha, Dogyeong; Kim, Taesung

    2016-01-01

    Photonic crystal structures can be created to manipulate electromagnetic waves so that many studies have focused on designing photonic band-gaps for various applications including sensors, LEDs, lasers, and optical fibers. Here, we show that mono-layered, self-assembled photonic crystals (SAPCs) fabricated by using an inkjet printer exhibit extremely weak structural colors and multiple colorful holograms so that they can be utilized in anti-counterfeit measures. We demonstrate that SAPC patterns on a white background are covert under daylight, such that pattern detection can be avoided, but they become overt in a simple manner under strong illumination with smartphone flash light and/or on a black background, showing remarkable potential for anti-counterfeit techniques. Besides, we demonstrate that SAPCs yield different RGB histograms that depend on viewing angles and pattern densities, thus enhancing their cryptographic capabilities. Hence, the structural colorations designed by inkjet printers would not only produce optical holograms for the simple authentication of many items and products but also enable a high-secure anti-counterfeit technique. PMID:27487978

  8. Inkjet Printing Based Mono-layered Photonic Crystal Patterning for Anti-counterfeiting Structural Colors

    NASA Astrophysics Data System (ADS)

    Nam, Hyunmoon; Song, Kyungjun; Ha, Dogyeong; Kim, Taesung

    2016-08-01

    Photonic crystal structures can be created to manipulate electromagnetic waves so that many studies have focused on designing photonic band-gaps for various applications including sensors, LEDs, lasers, and optical fibers. Here, we show that mono-layered, self-assembled photonic crystals (SAPCs) fabricated by using an inkjet printer exhibit extremely weak structural colors and multiple colorful holograms so that they can be utilized in anti-counterfeit measures. We demonstrate that SAPC patterns on a white background are covert under daylight, such that pattern detection can be avoided, but they become overt in a simple manner under strong illumination with smartphone flash light and/or on a black background, showing remarkable potential for anti-counterfeit techniques. Besides, we demonstrate that SAPCs yield different RGB histograms that depend on viewing angles and pattern densities, thus enhancing their cryptographic capabilities. Hence, the structural colorations designed by inkjet printers would not only produce optical holograms for the simple authentication of many items and products but also enable a high-secure anti-counterfeit technique.

  9. Inkjet Printing Based Mono-layered Photonic Crystal Patterning for Anti-counterfeiting Structural Colors.

    PubMed

    Nam, Hyunmoon; Song, Kyungjun; Ha, Dogyeong; Kim, Taesung

    2016-08-04

    Photonic crystal structures can be created to manipulate electromagnetic waves so that many studies have focused on designing photonic band-gaps for various applications including sensors, LEDs, lasers, and optical fibers. Here, we show that mono-layered, self-assembled photonic crystals (SAPCs) fabricated by using an inkjet printer exhibit extremely weak structural colors and multiple colorful holograms so that they can be utilized in anti-counterfeit measures. We demonstrate that SAPC patterns on a white background are covert under daylight, such that pattern detection can be avoided, but they become overt in a simple manner under strong illumination with smartphone flash light and/or on a black background, showing remarkable potential for anti-counterfeit techniques. Besides, we demonstrate that SAPCs yield different RGB histograms that depend on viewing angles and pattern densities, thus enhancing their cryptographic capabilities. Hence, the structural colorations designed by inkjet printers would not only produce optical holograms for the simple authentication of many items and products but also enable a high-secure anti-counterfeit technique.

  10. Hyperspectral optical near-field imaging: Looking graded photonic crystals and photonic metamaterials in color

    NASA Astrophysics Data System (ADS)

    Dellinger, Jean; Van Do, K.; Le Roux, Xavier; de Fornel, Frédérique; Cassan, Eric; Cluzel, Benoît

    2012-10-01

    Using a scanning near-field optical microscope operating with a hyperspectral detection scheme, we report the direct observation of the mirage effect within an on-chip integrated artificial material made of a two dimensional graded photonic crystal. The light rainbow due to the material dispersion is quantified experimentally and quantitatively compared to three dimensional plane wave assisted Hamiltonian optics predictions of light propagation.

  11. Mapping color fluctuations in the photon in ultraperipheral heavy ion collisions at the Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Alvioli, M.; Frankfurt, L.; Guzey, V.; Strikman, M.; Zhalov, M.

    2017-04-01

    We model effects of color fluctuations (CFs) in the light-cone photon wave function and for the first time make predictions for the distribution over the number of wounded nucleons ν in the inelastic photon-nucleus scattering. We show that CFs lead to a dramatic enhancement of this distribution at ν = 1 and large ν > 10. We also study the implications of different scales and CFs in the photon wave function on the total transverse energy ΣET and other observables in inelastic γA scattering with different triggers. Our predictions can be tested in proton-nucleus and nucleus-nucleus ultraperipheral collisions at the LHC and will help to map CFs, whose first indications have already been observed at the LHC.

  12. Tunable Design of Structural Colors Produced by Pseudo-1D Photonic Crystals of Graphene Oxide.

    PubMed

    Tong, Liping; Qi, Wei; Wang, Mengfan; Huang, Renliang; Su, Rongxin; He, Zhimin

    2016-07-01

    It is broadly observed that graphene oxide (GO) films appear transparent with a thickness of about several nanometers, whereas they appear dark brown or almost black with thickness of more than 1 μm. The basic color mechanism of GO film on a sub-micrometer scale, however, is not well understood. This study reports on GO pseudo-1D photonic crystals (p1D-PhCs) exhibiting tunable structural colors in the visible wavelength range owing to its 1D Bragg nanostructures. Striking structural colors of GO p1D-PhCs could be tuned by simply changing either the volume or concentration of the aqueous GO dispersion during vacuum filtration. Moreover, the quantitative relationship between thickness and reflection wavelength of GO p1D-PhCs has been revealed, thereby providing a theoretical basis to rationally design structural colors of GO p1D-PhCs. The spectral response of GO p1D-PhCs to humidity is also obtained clearly showing the wavelength shift of GO p1D-PhCs at differently relative humidity values and thus encouraging the integration of structural color printing and the humidity-responsive property of GO p1D-PhCs to develop a visible and fast-responsive anti-counterfeiting label. The results pave the way for a variety of potential applications of GO in optics, structural color printing, sensing, and anti-counterfeiting.

  13. Structural Color for Additive Manufacturing: 3D-Printed Photonic Crystals from Block Copolymers.

    PubMed

    Boyle, Bret M; French, Tracy A; Pearson, Ryan M; McCarthy, Blaine G; Miyake, Garret M

    2017-03-28

    The incorporation of structural color into 3D printed parts is reported, presenting an alternative to the need for pigments or dyes for colored parts produced through additive manufacturing. Thermoplastic build materials composed of dendritic block copolymers were designed, synthesized, and used to additively manufacture plastic parts exhibiting structural color. The reflection properties of the photonic crystals arise from the periodic nanostructure formed through block copolymer self-assembly during polymer processing. The wavelength of reflected light could be tuned across the visible spectrum by synthetically controlling the block copolymer molecular weight and manufacture parts that reflected violet, green, or orange light with the capacity to serve as selective optical filters and light guides.

  14. ECHO virus

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/001340.htm ECHO virus To use the sharing features on this page, please enable JavaScript. Enteric cytopathic human orphan (ECHO) viruses are a group of viruses that lead to ...

  15. Echo-seeding options for LCLS-II

    SciTech Connect

    Xiang, D.; Stupakov, G.; /SLAC

    2010-09-14

    The success of LCLS has opened up a new era of x-ray sciences. An upgrade to LCLS is currently being planned to enhance its capabilities. In this paper we study the feasibility of using the echo-enabled harmonic generation (EEHG) technique to generate narrow bandwidth soft x-ray radiation in the proposed LCLS-II soft x-ray beam line. We focus on the conceptual design, the technical implementation and the expected performances of the echo-seeding scheme. We will also show how the echo-seeding scheme allows one to generate two color x-ray pulses with the higher energy photons leading the lower energy ones as is favored in the x-ray pump-probe experiments.

  16. Diamond nanocrystals hosting single nitrogen-vacancy color centers sorted by photon-correlation near-field microscopy.

    PubMed

    Sonnefraud, Yannick; Cuche, Aurélien; Faklaris, Orestis; Boudou, Jean-Paul; Sauvage, Thierry; Roch, Jean-François; Treussart, François; Huant, Serge

    2008-03-15

    Diamond nanocrystals containing highly photoluminescent color centers are attractive, nonclassical, and near-field light sources. For near-field applications, the size of the nanocrystal is crucial, since it defines the optical resolution. Nitrogen-vacancy (NV) color centers are efficiently created by proton irradiation and annealing of a nanodiamond powder. Using near-field microscopy and photon statistics measurements, we show that nanodiamonds with sizes down to 25 nm can hold a single NV color center with bright and stable photoluminescence.

  17. Few-photon color imaging using energy-dispersive superconducting transition-edge sensor spectrometry.

    PubMed

    Niwa, Kazuki; Numata, Takayuki; Hattori, Kaori; Fukuda, Daiji

    2017-04-04

    Highly sensitive spectral imaging is increasingly being demanded in bioanalysis research and industry to obtain the maximum information possible from molecules of different colors. We introduce an application of the superconducting transition-edge sensor (TES) technique to highly sensitive spectral imaging. A TES is an energy-dispersive photodetector that can distinguish the wavelength of each incident photon. Its effective spectral range is from the visible to the infrared (IR), up to 2800 nm, which is beyond the capabilities of other photodetectors. TES was employed in this study in a fiber-coupled optical scanning microscopy system, and a test sample of a three-color ink pattern was observed. A red-green-blue (RGB) image and a near-IR image were successfully obtained in the few-incident-photon regime, whereas only a black and white image could be obtained using a photomultiplier tube. Spectral data were also obtained from a selected focal area out of the entire image. The results of this study show that TES is feasible for use as an energy-dispersive photon-counting detector in spectral imaging applications.

  18. Few-photon color imaging using energy-dispersive superconducting transition-edge sensor spectrometry

    PubMed Central

    Niwa, Kazuki; Numata, Takayuki; Hattori, Kaori; Fukuda, Daiji

    2017-01-01

    Highly sensitive spectral imaging is increasingly being demanded in bioanalysis research and industry to obtain the maximum information possible from molecules of different colors. We introduce an application of the superconducting transition-edge sensor (TES) technique to highly sensitive spectral imaging. A TES is an energy-dispersive photodetector that can distinguish the wavelength of each incident photon. Its effective spectral range is from the visible to the infrared (IR), up to 2800 nm, which is beyond the capabilities of other photodetectors. TES was employed in this study in a fiber-coupled optical scanning microscopy system, and a test sample of a three-color ink pattern was observed. A red–green–blue (RGB) image and a near-IR image were successfully obtained in the few-incident-photon regime, whereas only a black and white image could be obtained using a photomultiplier tube. Spectral data were also obtained from a selected focal area out of the entire image. The results of this study show that TES is feasible for use as an energy-dispersive photon-counting detector in spectral imaging applications. PMID:28374801

  19. Possibility of observing color-symmetry violation in the two-photon experiments of PLUTO at PETRA

    SciTech Connect

    Efremov, A.; Ivanov, S.

    1982-01-01

    The two-photon processes being studied by the PLUTO group at PETRA are discussed from the point of view of study of color symmetry. The reaction which is cleanest theoretically is the annihilation of two photons into two hadron jets with large transverse momentum. The PLUTO results for this process are compared with calculations using QCD and the calculations in the model of electrostrong interactions with violation of color symmetry. It is not clear whether the departure of the experimental results from QCD is due to an important role of higher twists or to the violation of color symmetry. (AIP)

  20. Single-photon emitters based on NIR color centers in diamond coupled with solid immersion lenses

    NASA Astrophysics Data System (ADS)

    Monticone, D. Gatto; Forneris, J.; Levi, M.; Battiato, A.; Picollo, F.; Olivero, P.; Traina, P.; Moreva, E.; Enrico, E.; Brida, G.; Degiovanni, I. P.; Genovese, M.; Amato, G.; Boarino, L.

    2014-12-01

    Single-photon sources represent a key enabling technology in quantum optics, and single color centers in diamond are a promising platform to serve this purpose, due to their high quantum efficiency and photostability at room temperature. The widely studied nitrogen-vacancy (NV) centers are characterized by several limitations, thus other defects have recently been considered, with a specific focus of centers emitting in the near-infra red (NIR). In the present work, we report on the coupling of native NIR-emitting centers in high-quality single-crystal diamond with solid immersion lens (SIL) structures fabricated by focused ion beam (FIB) lithography. The reported improvements in terms of light collection efficiency make the proposed system an ideal platform for the development of single-photon emitters with appealing photophysical and spectral properties.

  1. Photonic Crystals: Tunable Design of Structural Colors Produced by Pseudo-1D Photonic Crystals of Graphene Oxide (Small 25/2016).

    PubMed

    Tong, Liping; Qi, Wei; Wang, Mengfan; Huang, Renliang; Su, Rongxin; He, Zhimin

    2016-07-01

    The production of structural colors based on graphene oxide (GO) pseudo-one-dimensional photonic crystals (p1D-PhCs) in the visible spectrum is reported on page 3433 by W. Qi and co-workers. The structural colors could be tuned by simply changing either the volume or concentration of the aqueous GO dispersion. Moreover, GO p1D-PhCs exhibit visible and rapid responsiveness to humidity.

  2. Hydrophilic Modification of Multi-Walled Carbon Nanotube for Building Photonic Crystals with Enhanced Color Visibility and Mechanical Strength.

    PubMed

    Li, Feihu; Tang, Bingtao; Xiu, Jinghai; Zhang, Shufen

    2016-04-28

    Low color visibility and poor mechanical strength of polystyrene (PS) photonic crystal films have been the main shortcomings for the potential applications in paints or displays. This paper presents a simple method to fabricate PS/MWCNTs (multi-walled carbon nanotubes) composite photonic crystal films with enhanced color visibility and mechanical strength. First, MWCNTs was modified through radical addition reaction by aniline 2,5-double sulfonic acid diazonium salt to generate hydrophilic surface and good water dispersity. Then the MWCNTs dispersion was blended with PS emulsion to form homogeneous PS/MWCNTs emulsion mixtures and fabricate composite films through thermal-assisted method. The obtained films exhibit high color visibility under natural light and improved mechanical strength owing to the light-adsorption property and crosslinking effect of MWCNTs. The utilization of MWCNTs in improving the properties of photonic crystals is significant for various applications, such as in paints and displays.

  3. The mechanism of color change in the neon tetra fish: a light-induced tunable photonic crystal array.

    PubMed

    Gur, Dvir; Palmer, Benjamin A; Leshem, Ben; Oron, Dan; Fratzl, Peter; Weiner, Steve; Addadi, Lia

    2015-10-12

    The fresh water fish neon tetra has the ability to change the structural color of its lateral stripe in response to a change in the light conditions, from blue-green in the light-adapted state to indigo in the dark-adapted state. The colors are produced by constructive interference of light reflected from stacks of intracellular guanine crystals, forming tunable photonic crystal arrays. We have used micro X-ray diffraction to track in time distinct diffraction spots corresponding to individual crystal arrays within a single cell during the color change. We demonstrate that reversible variations in crystal tilt within individual arrays are responsible for the light-induced color variations. These results settle a long-standing debate between the two proposed models, the "Venetian blinds" model and the "accordion" model. The insight gained from this biogenic light-induced photonic tunable system may provide inspiration for the design of artificial optical tunable systems.

  4. Stimulated Photon Echo Studies of Protein-Matrix Solvation Dynamics and Interexciton-State Radiationless Decay in Allophycocyanin and α Phycocyanin

    NASA Astrophysics Data System (ADS)

    Beck, Warren F.; Homoelle, Bradley J.; Diffey, William M.

    1998-03-01

    We have employed two third-order femtosecond spectroscopic methods, stimulated-photon-echo peak-shift (3PEPS) and transient-grating (TG) spectroscopy, to characterize solvation dynamics at physiological temperatures in phycobiliprotein systems, the α subunit of C-phycocyanin and allophycocyanin in the trimeric aggregation state. Both systems exhibit a biphasic solvation response: an inertial phase, arising from librational motions of the amino acids or included water molecules in the chromophore-binding site, contributes a 80--100-fs component to the 3PEPS profile and appears as a rapidly-damped 72-cm-1 modulation of the TG signal; the diffusive phase, arising from collective protein-matrix motions, exhibits a component in the TG signal and 3PEPS profile on the 5--20-ps and longer time scales. The 3PEPS profile observed with allophycocyanin exhibits additional fast decay components, with time constants of 56 fs and 220 fs, that report the additional contributions to electronic dephasing that arise from interexciton-state radiationless decay and vibrational relaxation in the lower exciton state, respectively. These results, taken along with those of previous transient hole-burning experiments, show that the exciton states in allophycocyanin are imperfectly correlated.

  5. Local vibrations in disordered solids studied via single-molecule spectroscopy: Comparison with neutron, nuclear, Raman scattering, and photon echo data

    NASA Astrophysics Data System (ADS)

    Vainer, Yu. G.; Naumov, A. V.; Kador, L.

    2008-06-01

    The energy spectrum of low-frequency vibrational modes (LFMs) in three disordered organic solids—amorphous polyisobutylene (PIB), toluene and deuterated toluene glasses, weakly doped with fluorescent chromophore molecules of tetra-tert-butylterrylene (TBT) has been measured via single-molecule (SM) spectroscopy. Analysis of the individual temperature dependences of linewidths of single TBT molecules allowed us to determine the values of the vibrational mode frequencies and the SM-LFM coupling constants for vibrations in the local environment of the molecules. The measured LFM spectra were compared with the “Boson peak” as measured in pure PIB by inelastic neutron scattering, in pure toluene glass by low-frequency Raman scattering, in doped toluene glass by nuclear inelastic scattering, and with photon echo data. The comparative analysis revealed close agreement between the spectra of the local vibrations as measured in the present study and the literature data of the Boson peak in PIB and toluene. The analysis has also the important result that weak doping of the disordered matrices with nonpolar probe molecules whose chemical composition is similar to that of the matrix molecules does not influence the observed vibrational dynamics markedly. The experimental data displaying temporal stability on the time scale of a few hours of vibrational excitation parameters in local surroundings was obtained for the first time both for polymer and molecular glass.

  6. Site-specific vibrational dynamics of the CD3zeta membrane peptide using heterodyned two-dimensional infrared photon echo spectroscopy.

    PubMed

    Mukherjee, Prabuddha; Krummel, Amber T; Fulmer, Eric C; Kass, Itamar; Arkin, Isaiah T; Zanni, Martin T

    2004-06-01

    Heterodyned two-dimensional infrared (2D IR) spectroscopy has been used to study the amide I vibrational dynamics of a 27-residue peptide in lipid vesicles that encompasses the transmembrane domain of the T-cell receptor CD3zeta. Using 1-(13)C[Double Bond](18)O isotope labeling, the amide I mode of the 49-Leucine residue was spectroscopically isolated and the homogeneous and inhomogeneous linewidths of this mode were measured by fitting the 2D IR spectrum collected with a photon echo pulse sequence. The pure dephasing and inhomogeneous linewidths are 2 and 32 cm(-1), respectively. The population relaxation time of the amide I band was measured with a transient grating, and it contributes 9 cm(-1) to the linewidth. Comparison of the 49-Leucine amide I mode and the amide I band of the entire CD3zeta peptide reveals that the vibrational dynamics are not uniform along the length of the peptide. Possible origins for the large amount of inhomogeneity present at the 49-Leucine site are discussed.

  7. Design of an innovative gamma ray spectroscopy image-based telescope by assigning reciprocal vision color to each gamma photon depending on the energy of gamma photons

    NASA Astrophysics Data System (ADS)

    Rahmani Nejad, Akbar; Olia, M. A.

    2009-08-01

    In this paper an innovative method to devise a new astronomical observation instrument by simultaneous implementation of a gamma telescope and a gamma spectroscope is presented. Electromagnetic beams emitted from a star e.g. the sun is spread all electromagnetic spectrum from gamma rays to radio waves, but there is a fingerprint in such a wide spectrum that shows the exact fusion reaction which can be traced by associated gamma photons. This means if gamma photons, emitted from each part of sun, to be detected by this instrument, then spatial information is provided by telescope and information about the energy is recorded by spectrometer, by convolving two above mentioned data, there will be an illustration of a star like the sun that can show which area emits associated gamma photons that in turn illustrates the spatial distribution of elements that produce these gamma photons e.g. hydrogen, deuterium, tritium, helium, etc. we choose a reference color for each principle gamma photon, according to method similar to gamut color space of CIE [1], by specific linear transformation, or transformation matrix having photon-energy dependence coefficients, then there will be a colorful illustration of sun or any star (or even a GRB) that depicts distribution of elements, released energy, density of elements, etc. This information in turn will reveal the rate and topological variation of matter, energy, magnetic fields, etc. This information will also help to provide enough data to find spatial distribution function of energy, matter, variation and displacement of matters on stars and in turn, it will provide unique information about behaviors of stars. Finally, the method of vibrating holes to increase the spatial resolution of gamma detectors to hundreds times is presented. This method increases the spatial resolution of semiconductor-gamma telescopes to hundreds of times without decreasing the size of gamma sensor pixels and without any major effort to improve the

  8. Two-color single-photon emission from InAs quantum dots: toward logic information management using quantum light.

    PubMed

    Rivas, David; Muñoz-Matutano, Guillermo; Canet-Ferrer, Josep; García-Calzada, Raúl; Trevisi, Giovanna; Seravalli, Luca; Frigeri, Paola; Martínez-Pastor, Juan P

    2014-02-12

    In this work, we propose the use of the Hanbury-Brown and Twiss interferometric technique and a switchable two-color excitation method for evaluating the exciton and noncorrelated electron-hole dynamics associated with single photon emission from indium arsenide (InAs) self-assembled quantum dots (QDs). Using a microstate master equation model we demonstrate that our single QDs are described by nonlinear exciton dynamics. The simultaneous detection of two-color, single photon emission from InAs QDs using these nonlinear dynamics was used to design a NOT AND logic transference function. This computational functionality combines the advantages of working with light/photons as input/output device parameters (all-optical system) and that of a nanodevice (QD size of ∼ 20 nm) while also providing high optical sensitivity (ultralow optical power operational requirements). These system features represent an important and interesting step toward the development of new prototypes for the incoming quantum information technologies.

  9. Old relief printing applied to the current preparation of multi-color and high resolution colloidal photonic crystal patterns.

    PubMed

    Yang, Dongpeng; Ye, Siyun; Ge, Jianping

    2015-12-11

    Monodisperse SiO2 colloids are assembled into colloidal crystals in the mixture of monomer and solvent, which is transformed into a mechanochromic photonic crystal paper by polymerization. Following the relief printing strategy, the printing plates are pressed onto the paper to generate letters or images due to the contrast of structural color between the deformed and the undeformed paper, and the images can be permanently retained through UV curing. The wide tunable range of structural color for the current paper under deformation helps to realize multi-color printing. The localized deformation among or even inside the colloidal microcrystals renders the paper with a precise mechanochromic response to the printing plates and leads to the production of high resolution photonic crystal patterns.

  10. Echo's Legacy

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The Echo 1 Satellite is simply a very large balloon, the diameter of a 10 story building. Metallized Products, Inc. developed a special material for NASA used for the balloons's skin. For "bouncing signals," material had to be reflective, lightweight, and thin enough to be folded into a beach ball size canister for delivery into orbit, where it would automatically inflate. Material selected was mylar polyester, with a reflective layer of tiny aluminum particles so fine that Echo's skin had a thickness half that of cellophane on a cigarette package.

  11. Oscillations in two-dimensional photon-echo signals of excitonic and vibronic systems: Stick-spectrum analysis and its computational verification

    SciTech Connect

    Egorova, Dassia

    2014-01-21

    Stick-spectrum expressions for electronic two-dimensional (2D) photon-echo (PE) signal of a generic multi-level system are presented and employed to interrelate oscillations in individual peaks of 2D PE signal and the underlying properties (eigenstates and coherent dynamics) of excitonic or vibronic systems. When focusing on the identification of the origin of oscillations in the rephasing part of 2D PE it is found, in particular, that multiple frequencies in the evolution of the individual peaks do not necessarily directly reflect the underlying system dynamics. They may originate from the excited-state absorption contribution to the signal, or arise due to multi-level vibrational structure of the electronic ground state, and represent a superposition of system frequencies, while the latter may evolve independently. The analytical stick-spectrum predictions are verified and illustrated by numerical calculations of 2D PE signals of an excitonic trimer and of a displaced harmonic oscillator with unequal vibrational frequencies in the two electronic states. The excitonic trimer is the smallest excitonic oligomer where excited-state absorption may represent a superposition of excited-state coherences and significantly influence the phase of the observed oscillations. The displaced oscillator is used to distinguish between the frequencies of the ground-state and of the excited-state manifolds, and to demonstrate how the location of a cross peak in 2D pattern of the PE signal “predetermines” its oscillatory behavior. Although the considered models are kept as simple as possible for clarity, the stick-spectrum analysis provides a solid general basis for interpretation of oscillatory signatures in electronic 2D PE signals of much more complex systems with multi-level character of the electronic states.

  12. Oscillations in two-dimensional photon-echo signals of excitonic and vibronic systems: stick-spectrum analysis and its computational verification.

    PubMed

    Egorova, Dassia

    2014-01-21

    Stick-spectrum expressions for electronic two-dimensional (2D) photon-echo (PE) signal of a generic multi-level system are presented and employed to interrelate oscillations in individual peaks of 2D PE signal and the underlying properties (eigenstates and coherent dynamics) of excitonic or vibronic systems. When focusing on the identification of the origin of oscillations in the rephasing part of 2D PE it is found, in particular, that multiple frequencies in the evolution of the individual peaks do not necessarily directly reflect the underlying system dynamics. They may originate from the excited-state absorption contribution to the signal, or arise due to multi-level vibrational structure of the electronic ground state, and represent a superposition of system frequencies, while the latter may evolve independently. The analytical stick-spectrum predictions are verified and illustrated by numerical calculations of 2D PE signals of an excitonic trimer and of a displaced harmonic oscillator with unequal vibrational frequencies in the two electronic states. The excitonic trimer is the smallest excitonic oligomer where excited-state absorption may represent a superposition of excited-state coherences and significantly influence the phase of the observed oscillations. The displaced oscillator is used to distinguish between the frequencies of the ground-state and of the excited-state manifolds, and to demonstrate how the location of a cross peak in 2D pattern of the PE signal "predetermines" its oscillatory behavior. Although the considered models are kept as simple as possible for clarity, the stick-spectrum analysis provides a solid general basis for interpretation of oscillatory signatures in electronic 2D PE signals of much more complex systems with multi-level character of the electronic states.

  13. Simple approach to three-color two-photon microscopy by a fiber-optic wavelength convertor

    PubMed Central

    Li, Kuen-Che; Huang, Lynn L. H.; Liang, Jhih-Hao; Chan, Ming-Che

    2016-01-01

    A simple approach to multi-color two-photon microscopy of the red, green, and blue fluorescent indicators was reported based on an ultra-compact 1.03-μm femtosecond laser and a nonlinear fiber. Inside the nonlinear fiber, the 1.03-μm laser pulses were simultaneously blue-shifted to 0.6~0.8 μm and red-shifted to 1.2~1.4 μm region by the Cherenkov radiation and fiber Raman gain effects. The wavelength-shifted 0.6~0.8 μm and 1.2~1.4 μm radiations were co-propagated with the residual non-converted 1.03-μm pulses inside the same nonlinear fiber to form a fiber-output three-color femtosecond source. The application of the multi-wavelength sources on multi-color two-photon fluorescence microscopy were also demonstrated. Overall, due to simple system configuration, convenient wavelength conversion, easy wavelength tunability within the entire 0.7~1.35 μm bio-penetration window and less requirement for high power and bulky light sources, the simple approach to multi-color two-photon microscopy could be widely applicable as an easily implemented and excellent research tool for future biomedical and possibly even clinical applications. PMID:27896017

  14. Simple approach to three-color two-photon microscopy by a fiber-optic wavelength convertor.

    PubMed

    Li, Kuen-Che; Huang, Lynn L H; Liang, Jhih-Hao; Chan, Ming-Che

    2016-11-01

    A simple approach to multi-color two-photon microscopy of the red, green, and blue fluorescent indicators was reported based on an ultra-compact 1.03-μm femtosecond laser and a nonlinear fiber. Inside the nonlinear fiber, the 1.03-μm laser pulses were simultaneously blue-shifted to 0.6~0.8 μm and red-shifted to 1.2~1.4 μm region by the Cherenkov radiation and fiber Raman gain effects. The wavelength-shifted 0.6~0.8 μm and 1.2~1.4 μm radiations were co-propagated with the residual non-converted 1.03-μm pulses inside the same nonlinear fiber to form a fiber-output three-color femtosecond source. The application of the multi-wavelength sources on multi-color two-photon fluorescence microscopy were also demonstrated. Overall, due to simple system configuration, convenient wavelength conversion, easy wavelength tunability within the entire 0.7~1.35 μm bio-penetration window and less requirement for high power and bulky light sources, the simple approach to multi-color two-photon microscopy could be widely applicable as an easily implemented and excellent research tool for future biomedical and possibly even clinical applications.

  15. Highly Efficient and Excitation Tunable Two-Photon Luminescence Platform For Targeted Multi-Color MDRB Imaging Using Graphene Oxide

    NASA Astrophysics Data System (ADS)

    Pramanik, Avijit; Fan, Zhen; Chavva, Suhash Reddy; Sinha, Sudarson Sekhar; Ray, Paresh Chandra

    2014-08-01

    Multiple drug-resistance bacteria (MDRB) infection is one of the top three threats to human health according to the World Health Organization (WHO). Due to the large penetration depth and reduced photodamage, two-photon imaging is an highly promising technique for clinical MDRB diagnostics. Since most commercially available water-soluble organic dyes have low two-photon absorption cross-section and rapid photobleaching tendency, their applications in two-photon imaging is highly limited. Driven by the need, in this article we report extremely high two-photon absorption from aptamer conjugated graphene oxide (σ2PA = 50800 GM) which can be used for highly efficient two-photon fluorescent probe for MDRB imaging. Reported experimental data show that two-photon photoluminescence imaging color, as well as luminescence peak position can be tuned from deep blue to red, just by varying the excitation wavelength without changing its chemical composition and size. We have demonstrated that graphene oxide (GO) based two-photon fluorescence probe is capable of imaging of multiple antibiotics resistance MRSA in the first and second biological transparency windows using 760-1120 nm wavelength range.

  16. Highly Efficient and Excitation Tunable Two-Photon Luminescence Platform For Targeted Multi-Color MDRB Imaging Using Graphene Oxide

    PubMed Central

    Pramanik, Avijit; Fan, Zhen; Chavva, Suhash Reddy; Sinha, Sudarson Sekhar; Ray, Paresh Chandra

    2014-01-01

    Multiple drug-resistance bacteria (MDRB) infection is one of the top three threats to human health according to the World Health Organization (WHO). Due to the large penetration depth and reduced photodamage, two-photon imaging is an highly promising technique for clinical MDRB diagnostics. Since most commercially available water-soluble organic dyes have low two-photon absorption cross-section and rapid photobleaching tendency, their applications in two-photon imaging is highly limited. Driven by the need, in this article we report extremely high two-photon absorption from aptamer conjugated graphene oxide (σ2PA = 50800 GM) which can be used for highly efficient two-photon fluorescent probe for MDRB imaging. Reported experimental data show that two-photon photoluminescence imaging color, as well as luminescence peak position can be tuned from deep blue to red, just by varying the excitation wavelength without changing its chemical composition and size. We have demonstrated that graphene oxide (GO) based two-photon fluorescence probe is capable of imaging of multiple antibiotics resistance MRSA in the first and second biological transparency windows using 760–1120 nm wavelength range. PMID:25125143

  17. Two-color ghost interference with photon pairs generated in hot atoms

    SciTech Connect

    Ding Dongsheng; Zhou Zhiyuan; Shi Baosen; Zou Xubo; Guo Guangcan

    2012-09-15

    We report on an experimental observation of a two-photon ghost interference experiment. A distinguishing feature of our experiment is that the photons are generated via a non-degenerated spontaneous four-wave mixing process in a hot atomic ensemble; therefore the photon has narrow bandwidth. Besides, there is a large difference in frequency between two photons in a pair. Our works may be important to achieve more secure, large transmission capacity long-distance quantum communication.

  18. Photon-dominated regions around cool stars: The effects of the color temperature of the radiation field

    NASA Technical Reports Server (NTRS)

    Spaans, Marco; Tielens, A. G. G. M.; Dishoeck, Ewine F. Van; Bakes, E. L. O.

    1994-01-01

    We have investigated the influence of the color temperature of the illuminating radiation field on the chemical and thermal structure of photon-dominated regions (PDRs). We present the results of a study of the photoelectric efficiency of heating by large molecules such as polycyclic aromatic hydrocarbons (PAHs) and very small grains for radiation fields characterized by different effective temperatures. We show that the efficiency for cooler (T(sub eff) approximately = 6000-10,000 K) stars is at most an order of magnitude smaller than that for hotter (T(sub eff) approximately = 20,000-30,000 K) stars. While cooler radiation fields result in less ultraviolet photons capable of heating, the efficiency per absorbed photon is higher, because the grains become less positively charged. We also present detailed calculations of the chemistry and thermal balance for generic PDRs (n(sub 0) approximately = 10(exp 3), G(sub 0) approximately = 10(exp 3)). For cooler radiation fields, the H/H2 and C(+)/C/CO transition layers shift toward the surface of the PDR, because fewer photons are available to photodissociate H2 and CO and to ionize C. The dominant cooling lines are the (C II) 158 micron and the (O I) 63 micron lines for the hotter radiation fields, but cooling by CO becomes dominant for a color temperature of 6000 K or lower. The (C II)/CO and (O I)/CO ratios are found to be very good diagnostics for the color temperature of the radiation field.

  19. X-ray Echo Spectroscopy

    NASA Astrophysics Data System (ADS)

    Shvyd'ko, Yuri

    2016-02-01

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >108 ) with broadband ≃5 - 13 meV dispersing systems are introduced featuring more than 103 signal enhancement. The technique is general, applicable in different photon frequency domains.

  20. Two-color two-photon excited fluorescence of indole: determination of wavelength-dependent molecular parameters.

    PubMed

    Herbrich, Sebastian; Al-Hadhuri, Tawfik; Gericke, Karl-Heinz; Shternin, Peter S; Smolin, Andrey G; Vasyutinskii, Oleg S

    2015-01-14

    We present a detailed study of two-color two-photon excited fluorescence in indole dissolved in propylene glycol. Femtosecond excitation pulses at effective wavelengths from 268 to 293.33 nm were used to populate the two lowest indole excited states (1)La and (1)Lb and polarized fluorescence was then detected. All seven molecular parameters and the two-photon polarization ratio Ω containing information on two-photon absorption dynamics, molecular lifetime τf, and rotation correlation time τrot have been determined from experiment and analyzed as a function of the excitation wavelength. The analysis of the experimental data has shown that (1)Lb-(1)La inversion occurred under the conditions of our experiment. The two-photon absorption predominantly populated the (1)La state at all excitation wavelengths but in the 287-289 nm area which contained an absorption hump of the (1)Lb state 0-0 origin. The components of the two-photon excitation tensor S were analyzed giving important information on the principal tensor axes and absorption symmetry. The results obtained are in a good agreement with the results reported by other groups. The lifetime τf and the rotation correlation time τrot showed no explicit dependence on the effective excitation wavelength. Their calculated weighted average values were found to be τf = 3.83 ± 0.14 ns and τrot = 0.74 ± 0.06 ns.

  1. Two-color two-photon excited fluorescence of indole: Determination of wavelength-dependent molecular parameters

    NASA Astrophysics Data System (ADS)

    Herbrich, Sebastian; Al-Hadhuri, Tawfik; Gericke, Karl-Heinz; Shternin, Peter S.; Smolin, Andrey G.; Vasyutinskii, Oleg S.

    2015-01-01

    We present a detailed study of two-color two-photon excited fluorescence in indole dissolved in propylene glycol. Femtosecond excitation pulses at effective wavelengths from 268 to 293.33 nm were used to populate the two lowest indole excited states 1La and 1Lb and polarized fluorescence was then detected. All seven molecular parameters and the two-photon polarization ratio Ω containing information on two-photon absorption dynamics, molecular lifetime τf, and rotation correlation time τrot have been determined from experiment and analyzed as a function of the excitation wavelength. The analysis of the experimental data has shown that 1Lb-1La inversion occurred under the conditions of our experiment. The two-photon absorption predominantly populated the 1La state at all excitation wavelengths but in the 287-289 nm area which contained an absorption hump of the 1Lb state 0-0 origin. The components of the two-photon excitation tensor S were analyzed giving important information on the principal tensor axes and absorption symmetry. The results obtained are in a good agreement with the results reported by other groups. The lifetime τf and the rotation correlation time τrot showed no explicit dependence on the effective excitation wavelength. Their calculated weighted average values were found to be τf = 3.83 ± 0.14 ns and τrot = 0.74 ± 0.06 ns.

  2. Color-Coded Batteries - Electro-Photonic Inverse Opal Materials for Enhanced Electrochemical Energy Storage and Optically Encoded Diagnostics.

    PubMed

    O'Dwyer, Colm

    2016-07-01

    For consumer electronic devices, long-life, stable, and reasonably fast charging Li-ion batteries with good stable capacities are a necessity. For exciting and important advances in the materials that drive innovations in electrochemical energy storage (EES), modular thin-film solar cells, and wearable, flexible technology of the future, real-time analysis and indication of battery performance and health is crucial. Here, developments in color-coded assessment of battery material performance and diagnostics are described, and a vision for using electro-photonic inverse opal materials and all-optical probes to assess, characterize, and monitor the processes non-destructively in real time are outlined. By structuring any cathode or anode material in the form of a photonic crystal or as a 3D macroporous inverse opal, color-coded "chameleon" battery-strip electrodes may provide an amenable way to distinguish the type of process, the voltage, material and chemical phase changes, remaining capacity, cycle health, and state of charge or discharge of either existing or new materials in Li-ion or emerging alternative battery types, simply by monitoring its color change.

  3. Three-color femtosecond source for simultaneous excitation of three fluorescent proteins in two-photon fluorescence microscopy.

    PubMed

    Wang, Ke; Liu, Tzu-Ming; Wu, Juwell; Horton, Nicholas G; Lin, Charles P; Xu, Chris

    2012-09-01

    We demonstrate a fiber-based, three-color femtosecond source for simultaneous imaging of three fluorescent proteins (FPs) using two-photon fluorescence microscopy (2PM). The three excitation wavelengths at 775 nm, 864 nm and 950 nm, are obtained through second harmonic generation (SHG) of the 1550-nm pump laser and the 1728-nm and 1900-nm solitons generated through soliton self-frequency shift (SSFS) in a large-mode-area (LMA) fiber. These energetic pulses are well matched to the two-photon excitation peaks of red, cyan and yellow fluorescent proteins (TagRFPs, TagCFPs, and TagYFPs) for efficient excitation. We demonstrate simultaneous 2PM of human melanoma cells expressing a "rainbow" combination of these three fluorescent proteins.

  4. One-color two-photon mass-analyzed threshold ionization spectroscopy of ethyl bromide through a dissociative intermediate state

    NASA Astrophysics Data System (ADS)

    Tang, Bifeng; Zhang, Song; Wang, Yanmei; Tang, Ying; Zhang, Bing

    2005-10-01

    Mass-analyzed threshold ionization (MATI) spectra of ethyl bromide were obtained using one-color two-photon ionization through a dissociative intermediate state. Accurate values for the adiabatic ionization energy have been obtained, 83099±5 and 85454±5cm-1 for the X˜1E2 and X˜2E2 states of the ethyl bromide cation, respectively, giving a splitting of 2355±10cm-1. Compared with conventional photoelectron data, the two-photon MATI spectrum exhibited a more extensive vibrational structure with a higher resolution, mainly containing the modes involving the dissociation coordinate. The observed modes were analyzed and discussed in terms of wave packet evolving on the potential-energy surface of the dissociative state.

  5. Theory of quantum frequency translation of light in optical fiber: application to interference of two photons of different color.

    PubMed

    McGuinness, H J; Raymer, M G; McKinstrie, C J

    2011-09-12

    We study quantum frequency translation and two-color photon interference enabled by the Bragg scattering four-wave mixing process in optical fiber. Using realistic model parameters, we computationally and analytically determine the Green function and Schmidt modes for cases with various pump-pulse lengths. These cases can be categorized as either "non-discriminatory" or "discriminatory" in regards to their propensity to exhibit high-efficiency translation or high-visibility two-photon interference for many different shapes of input wave packets or for only a few input wave packets, respectively. Also, for a particular case, the Schmidt mode set was found to be nearly equal to a Hermite-Gaussian function set. The methods and results also apply with little modification to frequency conversion by sum-frequency conversion in optical crystals.

  6. Two-color interference effect involving three-photon atomic excitation and four-wave mixing in crossed laser beams

    SciTech Connect

    Peet, V.

    2007-09-15

    Through multiphoton ionization measurements, the polarization effects in destructive quantum interference under three-photon resonant excitation have been studied. Recent observations [V. Peet, Phys. Rev. A 74, 033406 (2006)] have indicated that contrary to the well-known pattern of a total suppression of resonance excitation, the destructive interference becomes incomplete if three-photon transition is driven by crossed beams with orthogonal polarization planes. These observations have been tested for a more general case of two-color excitation and very similar polarization-dependent anomalies in the interference character have been registered. It has been shown that the destructive interference is modified and the resonance excitation does occur if two crossed laser beams have opposite circular polarizations. The pressure-induced evolution of the uncanceled ionization peaks has the ratio of blue shift to width close to 0.5 exactly as it is known for resonance ionization peaks registered under excitation by counterpropagating laser beams.

  7. Structural color produced by a three-dimensional photonic polycrystal in the scales of a longhorn beetle: Pseudomyagrus waterhousei (Coleoptera: Cerambicidae).

    PubMed

    Simonis, Priscilla; Vigneron, Jean Pol

    2011-01-01

    The cuticle of the longhorn beetle Pseudomyagrus waterhousei shows a diffuse pattern of mixed blue and violet colors. These colorations arise from a dense layer of droplet-shaped scales covering the dorsal parts of the cuticle. In spite of their lack of iridescence, these colors are shown to be structural and produced by an aggregate of internally ordered photonic-crystal grains. Computer simulations confirm that the blue and violet colors are caused by face-centered-cubic crystallites which dominantly expose their (111) surface to illumination and viewing.

  8. Two-color two-photon excited fluorescence of indole: Determination of wavelength-dependent molecular parameters

    SciTech Connect

    Herbrich, Sebastian; Al-Hadhuri, Tawfik; Gericke, Karl-Heinz; Shternin, Peter S. Vasyutinskii, Oleg S.; Smolin, Andrey G.

    2015-01-14

    We present a detailed study of two-color two-photon excited fluorescence in indole dissolved in propylene glycol. Femtosecond excitation pulses at effective wavelengths from 268 to 293.33 nm were used to populate the two lowest indole excited states {sup 1}L{sub a} and {sup 1}L{sub b} and polarized fluorescence was then detected. All seven molecular parameters and the two-photon polarization ratio Ω containing information on two-photon absorption dynamics, molecular lifetime τ{sub f}, and rotation correlation time τ{sub rot} have been determined from experiment and analyzed as a function of the excitation wavelength. The analysis of the experimental data has shown that {sup 1}L{sub b}–{sup 1}L{sub a} inversion occurred under the conditions of our experiment. The two-photon absorption predominantly populated the {sup 1}L{sub a} state at all excitation wavelengths but in the 287–289 nm area which contained an absorption hump of the {sup 1}L{sub b} state 0-0 origin. The components of the two-photon excitation tensor S were analyzed giving important information on the principal tensor axes and absorption symmetry. The results obtained are in a good agreement with the results reported by other groups. The lifetime τ{sub f} and the rotation correlation time τ{sub rot} showed no explicit dependence on the effective excitation wavelength. Their calculated weighted average values were found to be τ{sub f} = 3.83 ± 0.14 ns and τ{sub rot} = 0.74 ± 0.06 ns.

  9. Luminescence Color Tuning by Regulating Electrostatic Interaction in Light-Emitting Devices and Two-Photon Excited Information Decryption.

    PubMed

    Ma, Yun; Liu, Shujuan; Yang, Huiran; Zeng, Yi; She, Pengfei; Zhu, Nianyong; Ho, Cheuk-Lam; Zhao, Qiang; Huang, Wei; Wong, Wai-Yeung

    2017-03-06

    It is well-known that the variation of noncovalent interactions of luminophores, such as π-π interaction, metal-to-metal interaction, and hydrogen-bonding interaction, can regulate their emission colors. Electrostatic interaction is also an important noncovalent interaction. However, very few examples of luminescence color tuning induced by electrostatic interaction were reported. Herein, a series of Zn(II)-bis(terpyridine) complexes (Zn-AcO, Zn-BF4, Zn-ClO4, and Zn-PF6) containing different anionic counterions were reported, which exhibit counterion-dependent emission colors from green-yellow to orange-red (549 to 622 nm) in CH2Cl2 solution. More importantly, it was found that the excited states of these Zn(II) complexes can be regulated by changing the electrostatic interaction between Zn(2+) and counterions. On the basis of this controllable excited state, white light emission has been achieved by a single molecule, and a white light-emitting device has been fabricated. Moreover, a novel type of data decryption system with Zn-PF6 as the optical recording medium has been developed by the two-photon excitation technique. Our results suggest that rationally controlled excited states of these Zn(II) complexes by regulating electrostatic interaction have promising applications in various optoelectronic fields, such as light-emitting devices, information recording, security protection, and so on.

  10. Electrical stimulation of non-classical photon emission from diamond color centers by means of sub-superficial graphitic electrodes

    PubMed Central

    Forneris, Jacopo; Traina, Paolo; Monticone, Daniele Gatto; Amato, Giampiero; Boarino, Luca; Brida, Giorgio; Degiovanni, Ivo P.; Enrico, Emanuele; Moreva, Ekaterina; Grilj, Veljko; Skukan, Natko; Jakšić, Milko; Genovese, Marco; Olivero, Paolo

    2015-01-01

    Focused MeV ion beams with micrometric resolution are suitable tools for the direct writing of conductive graphitic channels buried in an insulating diamond bulk, as already demonstrated for different device applications. In this work we apply this fabrication method to the electrical excitation of color centers in diamond, demonstrating the potential of electrical stimulation in diamond-based single-photon sources. Differently from optically-stimulated light emission from color centers in diamond, electroluminescence (EL) requires a high current flowing in the diamond subgap states between the electrodes. With this purpose, buried graphitic electrode pairs, 10 μm spaced, were fabricated in the bulk of a single-crystal diamond sample using a 6 MeV C microbeam. The electrical characterization of the structure showed a significant current injection above an effective voltage threshold of 150 V, which enabled the stimulation of a stable EL emission. The EL imaging allowed to identify the electroluminescent regions and the residual vacancy distribution associated with the fabrication technique. Measurements evidenced isolated electroluminescent spots where non-classical light emission in the 560–700 nm spectral range was observed. The spectral and auto-correlation features of the EL emission were investigated to qualify the non-classical properties of the color centers. PMID:26510889

  11. Electrical stimulation of non-classical photon emission from diamond color centers by means of sub-superficial graphitic electrodes

    NASA Astrophysics Data System (ADS)

    Forneris, Jacopo; Traina, Paolo; Monticone, Daniele Gatto; Amato, Giampiero; Boarino, Luca; Brida, Giorgio; Degiovanni, Ivo P.; Enrico, Emanuele; Moreva, Ekaterina; Grilj, Veljko; Skukan, Natko; Jakšić, Milko; Genovese, Marco; Olivero, Paolo

    2015-10-01

    Focused MeV ion beams with micrometric resolution are suitable tools for the direct writing of conductive graphitic channels buried in an insulating diamond bulk, as already demonstrated for different device applications. In this work we apply this fabrication method to the electrical excitation of color centers in diamond, demonstrating the potential of electrical stimulation in diamond-based single-photon sources. Differently from optically-stimulated light emission from color centers in diamond, electroluminescence (EL) requires a high current flowing in the diamond subgap states between the electrodes. With this purpose, buried graphitic electrode pairs, 10 μm spaced, were fabricated in the bulk of a single-crystal diamond sample using a 6 MeV C microbeam. The electrical characterization of the structure showed a significant current injection above an effective voltage threshold of 150 V, which enabled the stimulation of a stable EL emission. The EL imaging allowed to identify the electroluminescent regions and the residual vacancy distribution associated with the fabrication technique. Measurements evidenced isolated electroluminescent spots where non-classical light emission in the 560-700 nm spectral range was observed. The spectral and auto-correlation features of the EL emission were investigated to qualify the non-classical properties of the color centers.

  12. Dance of the Light Echoes

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Click on image for larger poster version

    This composite image from NASA's Spitzer Space Telescope shows the remnant of a star that exploded, called Cassiopeia A (center) and its surrounding 'light echoes' -- dances of light through dusty clouds, created when stars blast apart. The light echoes are colored and the surrounding clouds of dust are gray.

    In figure 1, dramatic changes are highlighted in phenomena referred to as light echoes (colored areas) around the Cassiopeia A supernova remnant (center). Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died.

    A light echo occurs when a star explodes, acting like a cosmic flashbulb. The light from this explosion zips through nearby dust clumps, illuminating and heating them up slightly. This brief period of warming causes them to glow in infrared, like a chain of Christmas bulbs lighting up one by one. The result is an optical illusion, in which the dust appears to be flying outward at the speed of light. In figure 1, this apparent motion can be seen here by the shift in colored dust clumps

    Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died. This remnant is located 11,000 light-years away in the northern constellation Cassiopeia.

    This composite consists of six processed images taken over a time span of three years. Dust features that have not changed over time appear gray, while those that have changed are colored blue or orange. Bluer colors represent an earlier time and redder ones, a later time. The progression of the light echo through the dust can be seen here by the shift in colored dust clumps.

    This

  13. Beam control and multi-color routing with spatial photonic defect modes.

    PubMed

    Wang, Xiaosheng; Chen, Zhigang

    2009-09-14

    We demonstrate tunable re-directing, blocking, and splitting of a light beam along defect channels based on spatial bandgap guidance in two-dimensional photonic lattices. We show the possibility for linear control of beam propagation and multicolor routing with specially designed junctions and surface structures embedded in otherwise uniform square lattices.

  14. Resonant-scanning dual-color STED microscopy with ultrafast photon counting: a concise guide

    PubMed Central

    Wu, Yong; Wu, Xundong; Toro, Ligia; Stefani, Enrico

    2015-01-01

    STED (stimulated emission depletion) is a popular super-resolution fluorescence microscopy technique. In this paper, we present a concise guide to building a resonant-scanning STED microscope with ultrafast photon-counting acquisition. The STED microscope has two channels, using a pulsed laser and a continuous-wave (CW) laser as the depletion laser source, respectively. The CW STED channel preforms time-gated detection to enhance optical resolution in this channel. We use a resonant mirror to attain high scanning speed and ultrafast photon counting acquisition to scan a large field of view, which help reduce photobleaching. We discuss some practical issues in building a STED microscope, including creating a hollow depletion beam profile, manipulating polarization, and monitoring optical aberration. We also demonstrate a STED image enhancement method using stationary wavelet expansion and image analysis methods to register objects and to quantify colocalization in STED microscopy. PMID:26123183

  15. Polarimetric, Two-Color, Photon-Counting Laser Altimeter Measurements of Forest Canopy Structure

    NASA Technical Reports Server (NTRS)

    Harding, David J.; Dabney, Philip W.; Valett, Susan

    2011-01-01

    Laser altimeter measurements of forest stands with distinct structures and compositions have been acquired at 532 nm (green) and 1064 nm (near-infrared) wavelengths and parallel and perpendicular polarization states using the Slope Imaging Multi-polarization Photon Counting Lidar (SIMPL). The micropulse, single photon ranging measurement approach employed by SIMPL provides canopy structure measurements with high vertical and spatial resolution. Using a height distribution analysis method adapted from conventional, 1064 nm, full-waveform lidar remote sensing, the sensitivity of two parameters commonly used for above-ground biomass estimation are compared as a function of wavelength. The results for the height of median energy (HOME) and canopy cover are for the most part very similar, indicating biomass estimations using lidars operating at green and near-infrared wavelengths will yield comparable estimates. The expected detection of increasing depolarization with depth into the canopies due to volume multiple-scattering was not observed, possibly due to the small laser footprint and the small detector field of view used in the SIMPL instrument. The results of this work provide pathfinder information for NASA's ICESat-2 mission that will employ a 532 nm, micropulse, photon counting laser altimeter.

  16. X-ray Photon Counting and Two-Color X-ray Imaging Using Indirect Detection

    PubMed Central

    Dierickx, Bart; Yao, Qiang; Witvrouwen, Nick; Uwaerts, Dirk; Vandewiele, Stijn; Gao, Peng

    2016-01-01

    In this paper, we report on the design and performance of a 1 cm2, 90 × 92-pixel image sensor. It is made X-ray sensitive by the use of a scintillator. Its pixels have a charge packet counting circuit topology with two channels, each realizing a different charge packet size threshold and analog domain event counting. Here, the sensor’s performance was measured in setups representative of a medical X-ray environment. Further, two-energy-level photon counting performance is demonstrated, and its capabilities and limitations are documented. We then provide an outlook on future improvements. PMID:27240362

  17. Photonic simulation method applied to the study of structural color in Myxomycetes.

    PubMed

    Dolinko, Andrés; Skigin, Diana; Inchaussandague, Marina; Carmaran, Cecilia

    2012-07-02

    We present a novel simulation method to investigate the multicolored effect of the Diachea leucopoda (Physarales order, Myxomycetes class), which is a microorganism that has a characteristic pointillistic iridescent appearance. It was shown that this appearance is of structural origin, and is produced within the peridium -protective layer that encloses the mass of spores-, which is basically a corrugated sheet of a transparent material. The main characteristics of the observed color were explained in terms of interference effects using a simple model of homogeneous planar slab. In this paper we apply a novel simulation method to investigate the electromagnetic response of such structure in more detail, i.e., taking into account the inhomogeneities of the biological material within the peridium and its curvature. We show that both features, which could not be considered within the simplified model, affect the observed color. The proposed method is of great potential for the study of biological structures, which present a high degree of complexity in the geometrical shapes as well as in the materials involved.

  18. Structure-color-species correlation in photonic nanoarchitectures occurring in blue lycaenid butterfly scales.

    PubMed

    Piszter, G; Kertész, K; Vértesy, Z; Mark, G I; Bálint, Zs; Biró, L P

    2012-11-01

    The blue colored males of nine Polyommatine butterfly species were investigated under the aspect of color-structure-species correlation. A large number of individuals from museum collections (in total more than 100) were used to obtain average reflectance spectra to reduce the effect of individual variations as much as possible. Structural characteristics were investigated by scanning electron microscopy and transmission electron microscopy. The relevant structural data were extracted using the Biophot Analyzer software. It was found that the position of the main reflectance peak is decided primarily by the nearest neighbor distance of holes in the perforated layers constituting the pepper-pot type structure. However, very different value of the 2D filling factor may have a large enough effect on the spectral position and the width and asymmetry of the peak to overrule the classification on taking into account only the nearest neighbor distance. The comparison of the structural and spectral data may indicate that the species Polyommatus amandus may constitute an evolutionary link between different groups of species. The examined pepper-pot type nanoarchitectures show that with the alteration of the structural parameters (first neighbor distance, 2D filling factor) the tuning of the reflectance of such nanoarchitectures may be achieved. These type of nanoarchitectures may be attractive for practical applications as their large scale manufacturing may require less strict conditions as compared with fully regular nanoarchitectures.

  19. ECHO Site Map | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  20. ECHO Rest Services Documentation | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  1. Resources - ECHO Data | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  2. Contact Us about ECHO | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  3. ECHO Release Notes | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  4. Learn More About ECHO | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  5. ECHO Gov Login | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  6. Intravital Confocal and Two-photon Imaging of Dual-color Cells and Extracellular Matrix Mimics

    PubMed Central

    Bal, Ufuk; Andresen, Volker; Baggett, Brenda; Utzinger, Urs

    2013-01-01

    To optimize imaging of cells in three dimensional culture we studied confocal backscattering, Second Harmonic Generation (SHG) and autofluorescence as source of contrast in extracellular matrix (ECM) mimics and evaluated the attenuation as well as bleaching of endogenous cellular fluorescence signals. All common ECM mimics exhibit contrast observable with confocal reflectance microscopy. SHG imaging on collagen I based hydrogels provides high contrast and good optical penetration depth. Agarose is a useful embedding medium because it allows for large optical penetration and exhibits minimal autofluorescence while still providing good reflectance to detect voids in the embedding medium. We labeled breast cancer cells’ outline with DsRed2 and nucleus with eGFP. DsRed2 can be excited with confocal imaging at 568nm, and with two photon excitation (TPE) in the red and longer NIR. eGFP was excited at 488nm for confocal and in the NIR for TPE. While there is small difference in the bleaching rate for eGFP between confocal and TPE we observed significant difference for DsRed2 where bleaching is strongest during TPE in the red wavelengths and smallest during confocal imaging. After a few hundred microns depth in a collagen I hydrogel, TPE fluorescence becomes twice as strong compared to confocal imaging. PMID:23380006

  7. X-ray echo spectroscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Shvyd'ko, Yuri V.

    2016-09-01

    X-ray echo spectroscopy, a counterpart of neutron spin-echo, was recently introduced [1] to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a point-like x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x-rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-meV and 0.02-meV ultra-high-resolution IXS applications (resolving power > 10^8) with broadband 5-13 meV dispersing systems will be presented featuring more than 1000-fold signal enhancement. The technique is general, applicable in different photon frequency domains. [1.] Yu. Shvyd'ko, Phys. Rev. Lett. 116, accepted (2016), arXiv:1511.01526.

  8. Comparison of gradient echo with spin echo magnetic resonance imaging and echocardiography in the evaluation of major aortopulmonary collateral arteries.

    PubMed

    Vick, G W; Wendt, R E; Rokey, R

    1994-05-01

    This study compared gradient echo magnetic resonance imaging, spin echo magnetic resonance imaging, echocardiography, and echocardiography with x-ray cineangiography in the evaluation of major aortopulmonary collateral arteries. Twelve patients (ages 9 months to 35 years, mean 11 +/- 11 years) with known or suspected major aortopulmonary collateral arteries were studied. The aortic insertion and proximal course of 29 major aortopulmonary collateral arteries demonstrated by x-ray contrast angiography were shown in all 29 cases by gradient echo magnetic resonance imaging but in only 23 of the 29 cases by spin echo magnetic resonance imaging. Color Doppler-echocardiography detected aortopulmonary collateral arteries in four patients but did not define the proximal course or distal anatomy. Gradient echo images of distal aortopulmonary collateral anatomy were qualitatively superior to spin echo images. The contrast-to-noise ratio between the vessel lumen and adjacent lung was greater for gradient echo (6.06 +/- 2.91) than for spin echo (1.45 +/- 1.13)(p < 0.05). Gradient echo magnetic resonance imaging is a useful method for identification and characterization of aortopulmonary collateral arteries in patients of all ages and is superior to spin echo magnetic resonance imaging and echocardiography.

  9. Selective two-photon fluorescence suppression by ultrafast pulse-pair excitation: control by selective one-color stimulated emission.

    PubMed

    Kumar De, Arijit; Roy, Debjit; Goswami, Debabrata

    2011-10-01

    Controlling two-photon molecular fluorescence leading to selective fluorophore excitation has been a long sought after goal in fluorescence microscopy. In this letter, we thoroughly explore selective fluorescence suppression through simultaneous two-photon absorption by two different fluorophores followed by selective one-photon stimulated emission for one particular fluorophore. We achieve this by precisely controlling the time delay between two identical ultrafast near infrared laser pulses.

  10. Light echoes - Type II supernovae

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.

    1987-01-01

    Type II supernovae (SNs) light curves show a remarkable range of shapes. Data have been collected for the 12 Type II SNs that have light curve information for more than four months past maximum. Contrary to previous reports, it is found that (1) the decay rate after 100 days past maximum varies by almost an order of magnitude and (2) the light curve shapes are not bimodally distributed, but actually form a continuum. In addition, it is found that the extinctions to the SNs are related to the light curve shapes. This implies that the absorbing dust is local to the SNs. The dust is likely to be part of a circumstellar shell emitted by the SN progenitor that Dwek (1983) has used to explain infrared echoes. The optical depth of the shell can get quite large. In such cases, it is found that the photons scattered and delayed by reflection off dust grains will dominate the light curve several months after peak brightness. This 'light echo' offers a straightforward explanation of the diversity of Type II SN light curves.

  11. Light echoes - Novae

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.

    1988-01-01

    The sudden brilliance of a nova eruption will be reflected on surrounding dust grains to create a phantom nebula. Previous searches for these light echoes have used relatively short exposures with photograhic detectors. This paper reports on a search around eight recent novae with long exposures using a CCD camera. Despite an increase of sensitivity by over an order of magnitude, no light echoes were detected. It is found that the average grain density must be less than about 10 to the -9th per cu cm for distances from 0.1 pc to 1000 pc from the novae. The light echo around Nova Persei 1901 was caused by reflection off clouds with grain densities of several times 10 to the -9th per cu cm which are at distances between 0.1 pc and 10 pc. Echoes from dust in a circumstellar shell or ejected during a previous eruption will be effectively unobservable.

  12. Resources | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  13. Dual-color multiple-particle tracking at 50-nm localization and over 100-µm range in 3D with temporal focusing two-photon microscopy

    PubMed Central

    Ding, Yu; Li, Chunqiang

    2016-01-01

    Nanoscale particle tracking in three dimensions is crucial to directly observe dynamics of molecules and nanoparticles in living cells. Here we present a three-dimensional particle tracking method based on temporally focused two-photon excitation. Multiple particles are imaged at 30 frames/s in volume up to 180 × 180 × 100 µm3. The spatial localization precision can reach 50 nm. We demonstrate its capability of tracking fast swimming microbes at speed of ~200 µm/s. Two-photon dual-color tracking is achieved by simultaneously exciting two kinds of fluorescent beads at 800 nm to demonstrate its potential in molecular interaction studies. Our method provides a simple wide-field fluorescence imaging approach for deep multiple-particle tracking. PMID:27867724

  14. Hematite Abundance Map at Echo

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows the hematite abundance map for a portion of the Meridiani Planum rock outcrop near where the Mars Exploration Rover Opportunity landed. It was acquired by the rover's miniature thermal emission spectrometer instrument from a spot called 'Echo.' Portions of the inner crater wall in this region appear rich in hematite (red). The sharp boundary from hematite-rich to hematite-poor (yellow and green) surfaces corresponds to a change in the surface texture and color. The hematite-rich surfaces have ripple-like forms suggesting wind transported hematite to these surfaces. The bounce marks produced during landing at the base of the slope on the left are low in hematite (blue). The hematite grains that originally covered the surface were pushed below the surface by the lander, exposing a soil that has less hematite.

  15. Synthesis of highly uniform Cu2O spheres by a two-step approach and their assembly to form photonic crystals with a brilliant color

    NASA Astrophysics Data System (ADS)

    Su, Xin; Chang, Jie; Wu, Suli; Tang, Bingtao; Zhang, Shufen

    2016-03-01

    Monodisperse semiconductor colloidal spheres with a high refractive index hold great potential for building photonic crystals with a strong band gap, but the difficulty in separating the nucleation and growth processes makes it challenging to prepare highly uniform semiconductor colloidal spheres. Herein, real monodisperse Cu2O spheres were prepared via a hot-injection & heating-up two-step method using diethylene glycol as a milder reducing agent. The diameter of the as prepared Cu2O spheres can be tuned from 90 nm to 190 nm precisely. The SEM images reveal that the obtained Cu2O spheres have a narrow size distribution, which permits their self-assembly to form photonic crystals. The effects of precursor concentration and heating rates on the size and morphology of the Cu2O spheres were investigated in detail. The results indicate that the key points of the method include the burst nucleation to form seeds at a high temperature followed by rapid cooling to prevent agglomeration, and appropriate precursor concentration as well as a moderate growth rate during the further growth process. Importantly, photonic crystal films exhibiting a brilliant structural color were fabricated with the obtained monodisperse Cu2O spheres as building blocks, proving the possibility of making photonic crystals with a strong band gap. The developed method was also successfully applied to prepare monodisperse CdS spheres with diameters in the range from 110 nm to 210 nm.Monodisperse semiconductor colloidal spheres with a high refractive index hold great potential for building photonic crystals with a strong band gap, but the difficulty in separating the nucleation and growth processes makes it challenging to prepare highly uniform semiconductor colloidal spheres. Herein, real monodisperse Cu2O spheres were prepared via a hot-injection & heating-up two-step method using diethylene glycol as a milder reducing agent. The diameter of the as prepared Cu2O spheres can be tuned from 90 nm to

  16. ECHO Status for International Partners

    NASA Technical Reports Server (NTRS)

    Weinstein, Beth; Lubelczyk, Jeff

    2006-01-01

    The EOS Clearinghouse (ECHO) is a clearinghouse of spatial and temporal metadata, inclusive of NASA's Distributed Active Archive Center (DAAC) data holdings, that enables the science community to more easily exchange NASA data and information. Currently, ECHO has metadata descriptors for over 55 million individual data granules and 13 million browse images. The majority of ECHO's holdings come directly from data held in the NASA DAACs. The science disciplines and domains represented in ECHO are diverse and include metadata for all of NASA's Science Focus Area data. As middleware for a service-oriented enterprise, ECHO offers access to its capabilities through a set of publicly available Application Program Interfaces (APIs). More information about ECHO is available at http://eos.nasa.gov.echo. The presentation will discuss the status of the ECHO Partners, holdings, and activities, including the transition from the EOS Data Gateway to the Warehouse Inventory Search Tool (WIST)

  17. Rotary echo nutation NMR

    NASA Astrophysics Data System (ADS)

    Janssen, R.; Tijink, G. A. H.; Veeman, W. S.

    1988-01-01

    A two-dimensional solid state NMR experiment which combines rotary echoes and nutation NMR is investigated and used to study different sodium sites in zeolite NaA. It is shown that with this technique sodium ions with different relaxation rates in the rotating frame can be distinguished.

  18. Echo Boom Impact

    ERIC Educational Resources Information Center

    Dordai, Phillipe; Rizzo, Joseph

    2006-01-01

    Like their baby-boomer parents, the echo-boom generation is reshaping the college and university landscape. At 80 million strong, this group of children and young adults born between 1980 and 1995 now is flooding the college and university system, spurring a college building boom. According to Campus Space Crunch, a Hillier Architecture survey of…

  19. CHRONICLE: Second All-Union Symposium on Optical Echo, Kazan, June 17-19, 1981

    NASA Astrophysics Data System (ADS)

    Samartsev, V. V.

    1982-05-01

    A brief review is given of the papers presented at the Second All-Union Symposium on Optical Echo, which was held in Kazan on June 17-19, 1981. The following topics were discussed at the Symposium: optical (photon) and phonon echo, self-induced transparency, nutation, superradiance, superscattering, and spectroscopic applications of these phenomena.

  20. Loschmidt echo and time reversal in complex systems

    PubMed Central

    Goussev, Arseni; Jalabert, Rodolfo A.; Pastawski, Horacio M.; Wisniacki, Diego A.

    2016-01-01

    Echoes are ubiquitous phenomena in several branches of physics, ranging from acoustics, optics, condensed matter and cold atoms to geophysics. They are at the base of a number of very useful experimental techniques, such as nuclear magnetic resonance, photon echo and time-reversal mirrors. Particularly interesting physical effects are obtained when the echo studies are performed on complex systems, either classically chaotic, disordered or many-body. Consequently, the term Loschmidt echo has been coined to designate and quantify the revival occurring when an imperfect time-reversal procedure is applied to a complex quantum system, or equivalently to characterize the stability of quantum evolution in the presence of perturbations. Here, we present the articles which discuss the work that has shaped the field in the past few years. PMID:27140977

  1. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Principles of construction of optical echo processors

    NASA Astrophysics Data System (ADS)

    Manykin, É. A.; Chernyshev, N. A.

    1991-09-01

    An analysis is made of the possibility of utilization of the photon echo effect in optical digital processing of discrete images by the method of control operators, which makes it possible to solve a number of problems. Different regimes for the excitation of the photon echo are in practice usable in all component parts of a processor, which makes this effect potentially promising for the use in optical data processing.

  2. Single-photon, Dual-color, Polarimetric Laser Altimeter Measurements of Lake Ice Freeboard, Roughness and Scattering Properties

    NASA Astrophysics Data System (ADS)

    Harding, D. J.; Dabney, P.; Valett, S.; Shuman, C. A.

    2009-12-01

    The Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) is an advanced technology airborne laser altimeter developed with a focus on remote sensing of ice sheets and sea ice including their melt state. Its development was sponsored by the NASA Earth Science Technology Office Instrument Incubator Program. SIMPL utilizes micropulse single photon laser ranging at 532 nm (green) and 1064 nm (near-infrared) wavelengths in a four-beam push-broom configuration. Currently, the instrument is capable of flight altitudes of up to 5000 m; this spreads the 4 profiles over a cross-track distance of 30 m providing an estimate of both along-track and cross-track slope magnitudes and directions. For both wavelengths on each beam, depolarization is measured as the ratio of received energy perpendicular and parallel to the plane-polarized transmit beams. The precision of the single photon ranges is 8 cm and a range observation is acquired every 5 to 10 cm at airborne flight speeds. This performance enables measurement of ice freeboard and surface roughness at 5 m length scales based on the height dispersion of single photon ranges aggregated along the profiles. The depolarization ratio is a function of the scattering properties of the target, specifically the proportions of specular reflection and surface and volume scattering. The relationship between surface roughness and depolarization at green and near-IR wavelengths will be illustrated using data acquired during flights over Lake Erie ice cover in February 2009, an analog for sea ice. Observed in simultaneously acquired digital video frames, the ice cover appears to be a heterogeneous amalgamation of ice types, thicknesses and ages. The lake ice is covered by snow in places and contains numerous open water leads to enable ice freeboard detection relative to the water surface. The depolarization ratio differentiates open water, young clear ice, older granular ice and snow cover. The variability of the ratio along a

  3. Two-Photon Dye Cocktail for Dual-Color 3D Imaging of Pancreatic Beta and Alpha Cells in Live Islets.

    PubMed

    Agrawalla, Bikram Keshari; Lee, Hyo Won; Phue, Wut-Hmone; Raju, Anandhkumar; Kim, Jong-Jin; Kim, Hwan Myung; Kang, Nam-Young; Chang, Young-Tae

    2017-03-08

    Insulin-secreting beta cells together with glucagon-producing alpha cells play an essential role in maintaining the optimal blood glucose level in the body, so the development of selective probes for imaging of these cell types in live islets is highly desired. Herein we report the development of a 2-glucosamine-based two-photon fluorescent probe, TP-β, that is suitable for imaging of beta cells in live pancreatic islets from mice. Flow cytometry studies confirmed that TP-β is suitable for isolation of primary beta cells. Moreover, two-photon imaging of TP-β-stained pancreatic islets showed brightly stained beta cells in live islets. Insulin enzyme-linked immunosorbent assays revealed that TP-β has no effect on glucose-stimulated insulin secretion from the stained islet. Finally, to develop a more convenient islet imaging application, we combined our recently published alpha-cell-selective probe TP-α with TP-β to make a "TP islet cocktail". This unique dye cocktail enabled single excitation (820 nm) and simultaneous dual-color imaging of alpha cells (green) and beta cells (red) in live pancreatic islets. This robust TP islet cocktail may serve as a valuable tool for basic diabetic studies.

  4. Project Echo: Receiving System

    NASA Technical Reports Server (NTRS)

    Ohm, E. A.

    1961-01-01

    A tracking horn-reflector antenna, a maser preamplifier (and standby parametric preamplifier), and a special FM demodulator were combined to form a low-noise receiving system which made possible the establishment of a high-quality voice circuit via the Echo I passive satellite. This paper describes the 2390-Mc receiving system located at the Bell Telephone Laboratories facility in Holmdel, New Jersey.

  5. Echo: skin stress test

    NASA Technical Reports Server (NTRS)

    1960-01-01

    Skin Stress Test of the 12-foot satellite built as a prototype of the full-scale Echo satellite. The 12-foot diameter of the sphere was chosen because that was the ceiling height in the Langley model shop. The proposal to build the 12-foot satellite was made in November 1957. - Published in James R. Hansen, Spaceflight Revolution: NASA Langley Research Center From Sputnik to Apollo, NASA SP-4308, pp. 170-171.

  6. Spin echo in synchrotrons

    NASA Astrophysics Data System (ADS)

    Chao, Alexander W.; Courant, Ernest D.

    2007-01-01

    As a polarized beam is accelerated through a depolarization resonance, its polarization is reduced by a well-defined calculable reduction factor. When the beam subsequently crosses a second resonance, the final beam polarization is considered to be reduced by the product of the two reduction factors corresponding to the two crossings, each calculated independently of the other. This is a good approximation when the spread of spin precession frequency Δνspin of the beam (particularly due to its energy spread) is sufficiently large that the spin precession phases of individual particles smear out completely during the time τ between the two crossings. This approximate picture, however, ignores two spin dynamics effects: an interference-overlap effect and a spin echo effect. This paper is to address these two effects. The interference-overlap effect occurs when Δνspin is too small, or when τ is too short, to complete the smearing process. In this case, the two resonance crossings overlap each other, and the final polarization exhibits constructive or destructive interference patterns depending on the exact value of τ. Typically, the beam’s energy spread is large and this interference-overlap effect does not occur. To study this effect, therefore, it is necessary to reduce the beam energy spread and to consider two resonance crossings very close to each other. The other mechanism, also due to the interplay between two resonance crossings, is spin echo. It turns out that even when the precession phases appear to be completely smeared between the two crossings, there will still be a sudden and short-lived echo signal of beam polarization at a time τ after the second crossing; the magnitude of which can be as large as 57%. This echo signal exists even when the beam has a sizable energy spread and when τ is very large, and could be a sensitive (albeit challenging) way to experimentally test the intricate spin dynamics in a synchrotron. After giving an analysis

  7. Spin Echo in Synchrotrons

    SciTech Connect

    Chao, Alexander W.; Courant, Ernest D.; /Brookhaven

    2006-12-01

    As a polarized beam is accelerated through a depolarization resonance, its polarization is reduced by a well-defined calculable reduction factor. When the beam subsequently crosses a second resonance, the final beam polarization is considered to be reduced by the product of the two reduction factors corresponding to the two crossings, each calculated independently of the other. This is a good approximation when the spread of spin precession frequency {Delta}{nu}{sub spin} of the beam (particularly due to its energy spread) is sufficiently large that the spin precession phases of individual particles smear out completely during the time {tau} between the two crossings. This approximate picture, however, ignores two spin dynamics effects: an interference effect and a spin echo effect. This paper is to address these two effects. The interference effect occurs when {Delta}{nu}{sub spin} is too small, or when {tau} is too short, to complete the smearing process. In this case, the two resonance crossings interfere with each other, and the final polarization exhibits constructive or destructive patterns depending on the exact value of {tau}. Typically, the beam's energy spread is large and this interference effect does not occur. To study this effect, therefore, it is necessary to reduce the beam energy spread and to consider two resonance crossings very close to each other. The other mechanism, also due to the interplay between two resonance crossings, is spin echo. It turns out that even when the precession phases appear to be completely smeared between the two crossings, there will still be a sudden and short-lived echo signal of beam polarization at a time {tau} after the second crossing; the magnitude of which can be as large as 57%. This echo signal exists even when the beam has a sizable energy spread and when {tau} is very large, and could be a sensitive (albeit challenging) way to experimentally test the intricate spin dynamics in a synchrotron. After giving an

  8. Faraday rotation echo spectroscopy and detection of quantum fluctuations.

    PubMed

    Chen, Shao-Wen; Liu, Ren-Bao

    2014-04-15

    Central spin decoherence is useful for detecting many-body physics in environments and moreover, the spin echo control can remove the effects of static thermal fluctuations so that the quantum fluctuations are revealed. The central spin decoherence approach, however, is feasible only in some special configurations and often requires uniform coupling between the central spin and individual spins in the baths, which are very challenging in experiments. Here, by making analogue between central spin decoherence and depolarization of photons, we propose a scheme of Faraday rotation echo spectroscopy (FRES) for studying quantum fluctuations in interacting spin systems. The echo control of the photon polarization is realized by flipping the polarization with a birefringence crystal. The FRES, similar to spin echo in magnetic resonance spectroscopy, can suppress the effects of the static magnetic fluctuations and therefore reveal dynamical magnetic fluctuations. We apply the scheme to a rare-earth compound LiHoF4 and calculate the echo signal, which is related to the quantum fluctuations of the system. We observe enhanced signals at the phase boundary. The FRES should be useful for studying quantum fluctuations in a broad range of spin systems, including cold atoms, quantum dots, solid-state impurities, and transparent magnetic materials.

  9. Light Echoes of Historic Transients

    NASA Astrophysics Data System (ADS)

    Rest, Armin; Sinnott, B.; Welch, D. L.; Prieto, J. L.; Bianco, F.

    2014-01-01

    Light echoes, light from a variable source scattered off dust, have been observed for over a century. The recent discovery of light echoes around centuries-old supernovae in the Milky Way and the Large Magellanic Cloud have allowed the spectroscopic characterization of these events, even without contemporaneous photometry and spectroscopy using modern instrumentation. Here we review the recent scientific advances using light echoes of ancient and historic transients, and focus on our latest work on SN 1987A's and Eta Carinae's light echoes.

  10. Lifetime Reduction and Enhanced Emission of Single Photon Color Centers in Nanodiamond via Surrounding Refractive Index Modification

    PubMed Central

    Khalid, Asma; Chung, Kelvin; Rajasekharan, Ranjith; Lau, Desmond W.M.; Karle, Timothy J.; Gibson, Brant C.; Tomljenovic-Hanic, Snjezana

    2015-01-01

    The negatively-charged nitrogen vacancy (NV−) center in diamond is of great interest for quantum information processing and quantum key distribution applications due to its highly desirable long coherence times at room temperature. One of the challenges for their use in these applications involves the requirement to further optimize the lifetime and emission properties of the centers. Our results demonstrate the reduction of the lifetime of NV− centers, and hence an increase in the emission rate, achieved by modifying the refractive index of the environment surrounding the nanodiamond (ND). By coating the NDs in a polymer film, experimental results and numerical calculations show an average of 63% reduction in the lifetime and an average enhancement in the emission rate by a factor of 1.6. This strategy is also applicable for emitters other than diamond color centers where the particle refractive index is greater than the refractive index of the surrounding media. PMID:26109500

  11. APPLICATIONS OF LASERS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Principles for construction of a Hopfield neuron network with the aid of volume echo holograms

    NASA Astrophysics Data System (ADS)

    Manykin, É. A.; Belov, M. N.

    1991-02-01

    A theoretical investigation is reported of the properties of the photon echo as a method for dynamic holography of three-dimensional media. It is shown that an optical Hopfield neuron network can be constructed on this basis. Potential applications of the photon echo in other tasks involving neuron networks in optics are considered.

  12. Neutron Speed Echo Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ioffe, A.

    Neutron speed echo (NSPE) technique is in a way a generalization of the neutron spin echo (NSE) technique. Similar to NSE spectrometers, the resolution of such NSPE spectrometer is extremely high and is not connected with the monochromatization of the incoming beam. However, in contrast to NSE spectrometers, the operation of proposed spectrometer does not necessarily require a polarized neutron beam. Such decoupling the polarization and the resolution is in clear contrast to NSE technique. Because the resolution of a NSPE spectrometer can be a few orders higher than the resolution of NSE spectrometers, one can achieve the energy resolution of about 10-14 eV by the use of ultra cold neutrons; a fact that can be used in some fundamental physics experiments. Though the scattering on the sample impose limitations on the resolution of a NSPE spectrometer, the use of the proposed technique in a low-resolution mode can be useful in the combination with triple-axis spectrometers and allow for the significant improvement of their energy resolution, however, without the use of polarized neutrons. This fact opens new possibilities for the study of magnetic phenomena in solids, where the NSE method is principally not applicable because of the neutron precession in the sample, especially by combining polarization analysis with high-resolution spectroscopy. The proposed technique also allows for an easy implementation of the principle of the NSE focusing, when the resolution ellipse is aligned along a dispersion curve.

  13. Dissecting a Light Echo

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Click on image for audio animation

    This animation illustrates how a light echo works, and how an optical illusion of material moving outward is created.

    A light echo occurs when a star explodes, acting like a cosmic flashbulb. The light from this explosion zips through nearby dust clumps, illuminating and heating them up slightly. This brief period of warming causes them to glow in infrared, like a chain of Christmas bulbs lighting up one by one.

    The animation starts by showing the explosion of a star, which results in a flash of light that moves outward in all directions. The direction of our line of sight from Earth is indicated by the blue arrow.

    When the light flash reaches surrounding dust, shown here as three dark clouds, the dust is heated up, creating infrared light that begins to travel toward Earth (indicated by the red arrows). Dust closest to the explosion lights up first, while the explosion's shock wave takes longer to reach more distant material. This results in light from different parts of the cloud reaching Earth at different times, creating the illusion of motion over time.

    As the animation shows, the inclination of the cloud toward our line of sight can result in the material seeming to move both away from and toward the central star.

  14. Echo 1 container

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Echo 1 container: The design of this container was one of the most difficult technical tasks. Hansen writes: 'After several weeks of examining potential solutions to this problem, the Langley engineers narrowed the field of ideas to five. They then built working models of these five container designs, and 12-foot-diameter models of the satellite for simulation studies. With help from Langley's Engineering Service and Mechanical Service divisions, the Echo group built a special 41-foot-diameter spherical vacuum chamber equipped with pressure-proof windows. There the dynamics of opening the container and inflating the satelloon could be studies as the satelloon fell to the bottom of the tank.' 'The container-opening mechanism that eventually resulted from these vacuum tests was surely one of the oddest explosive devices ever contrived. The container was a sphere that opened at its equator into top and bottom hemispheres. the top half fit on the bottom half much like a lid fits snugly atop a kitchen pot. The joint between the two hemispheres, therefore, formed a sliding valve. The halves had to move apart an inch or two before the canister was actually open. It was in this joint between the hemispheres that the charge was placed.' The whole whole system was laced together with fishing line which resulted in many disdainful comments from visiting scientists and engineers but the system worked. Published in James R. Hansen, Spaceflight Revolution: NASA Langley Research Center From Sputnik to Apollo, (Washington: NASA, 1995), p. 180.

  15. Rotamers of m-chloroanisole studied by two-color resonant two-photon mass-analyzed threshold ionization spectroscopy

    NASA Astrophysics Data System (ADS)

    Huang, Hsin Chang; Shiung, Kui Shiu; Jin, Bih Yaw; Tzeng, Wen Bih

    2013-11-01

    We apply the resonant two-photon ionization (R2PI) and mass-analyzed threshold ionization (MATI) techniques to record the vibronic and cation spectra of m-chloroanisole. The vibronic features appear in two series, built on 35,822 ± 2 and 35,868 ± 2 cm-1, corresponding to the origins of the S1 ← S0 electronic transition (E1's) of the two rotamers. Analysis of the MATI spectra gives the adiabatic ionization energies (IEs) of 67,645 ± 5 and 68,008 ± 5 cm-1 for these two isomeric species. Comparing these data with those of anisole, we find that the chlorine substitution at the meta position leads to a red shift in the E1 and a blue shift in the IE. The observed R2PI and MATI bands mainly result from the in-plane ring deformation and substituent-sensitive bending vibrations of these species in the electronically excited S1 and cationic ground D0 states.

  16. Analytical model of photon reabsorption in ZnO quantum dots with size and concentration dependent dual-color photoluminescence

    NASA Astrophysics Data System (ADS)

    Fan, Baolu; Guo, Xiaoxiao; Zhang, Yumeng; Fan, Jiyang

    2017-02-01

    We investigate the concentration and size dependent UV/green photoluminescence properties of the ZnO quantum dots (QDs) with sizes in the strong confinement regime. The luminescence characteristics of an ensemble of colloidal semiconductor QDs with quantum confinement effect depend sensitively on particle concentration but this has only been qualitatively understood. By taking ZnO QDs as an ideal prototype, we construct a material-independent theoretical model to study the photon reabsorption phenomenon. The theoretical result agrees well with the experiment. This model can be used to quantitatively study the concentration-dependent luminescence properties of any collection of QDs with considerable size dispersion. On the other hand, the origin of green emission in ZnO QDs remains debated. The comparative study of the size dependence of UV and green emissions in conjunction with the effective-mass approximation calculation suggests that the green emission in the ZnO QDs originates from the conduction band to the deep level transition.

  17. Simple Echoes and Subtle Reverberations

    ERIC Educational Resources Information Center

    Keeports, David

    2010-01-01

    Reverberation within an enclosed space can be viewed as a superposition of a large number of simple echoes. The echoes that make up the sound of reverberation fall neatly into two categories, relatively loud and sparse early reflections, and relatively soft and dense late reflections. Ways in which readily available music production software can…

  18. Light Echoes and Late-Time Emissions of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Drozdov, Dina

    2016-05-01

    progenitor. The dust is closer to the supernova for the echo in SN 2009ig. Exploring the color of the echoes gives implications on the dust type, and both light echo cases have atypical color evolution from model predictions, which suggests abnormal dust is involved. The echoes from SN 2006X and double echo from SN 1998bu show the evolution of the echoes over a long time period, which can be compared to past findings by multiple teams. The echoes show remarkable similarity to other Type Ia echo detections, and with more discoveries, the transition of light echoes from normal emission can be investigated, which could further probe the supernova ejecta. Using a process we developed, we calculate the magnitude differences between Hubble Space Telescope and standard filters in the case of normal supernovae. We conclude by comparing all light echo detections to date and discussing the future goals of this work.

  19. Guide to Regulated Facilities in ECHO | ECHO | US EPA

    EPA Pesticide Factsheets

    There are multiple ways ECHO can be used to search compliance data. By default, ECHO searches focus on larger, more regulated facilities. Each search page allows users to search a more comprehensive group of facilities by electing to search for minor or smaller facilities. Information is presented that explains the types and approximate numbers of facilities that are included in searches when the default and custom options are used.

  20. Effluent Charts | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  1. Enforcement Cases | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  2. Data Downloads | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide for searching and downloading. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  3. Image domain propeller fast spin echo.

    PubMed

    Skare, Stefan; Holdsworth, Samantha J; Lilja, Anders; Bammer, Roland

    2013-04-01

    A new pulse sequence for high-resolution T2-weighted (T2-w) imaging is proposed - image domain propeller fast spin echo (iProp-FSE). Similar to the T2-w PROPELLER sequence, iProp-FSE acquires data in a segmented fashion, as blades that are acquired in multiple TRs. However, the iProp-FSE blades are formed in the image domain instead of in the k-space domain. Each iProp-FSE blade resembles a single-shot fast spin echo (SSFSE) sequence with a very narrow phase-encoding field of view (FOV), after which N rotated blade replicas yield the final full circular FOV. Our method of combining the image domain blade data to a full FOV image is detailed, and optimal choices of phase-encoding FOVs and receiver bandwidths were evaluated on phantom and volunteers. The results suggest that a phase FOV of 15-20%, a receiver bandwidth of ±32-63 kHz and a subsequent readout time of about 300 ms provide a good tradeoff between signal-to-noise ratio (SNR) efficiency and T2 blurring. Comparisons between iProp-FSE, Cartesian FSE and PROPELLER were made on single-slice axial brain data, showing similar T2-w tissue contrast and SNR with great anatomical conspicuity at similar scan times - without colored noise or streaks from motion. A new slice interleaving order is also proposed to improve the multislice capabilities of iProp-FSE.

  4. Rapid Gradient-Echo Imaging

    PubMed Central

    Hargreaves, Brian

    2012-01-01

    Gradient echo sequences are widely used in magnetic resonance imaging (MRI) for numerous applications ranging from angiography to perfusion to functional MRI. Compared with spin-echo techniques, the very short repetition times of gradient-echo methods enable very rapid 2D and 3D imaging, but also lead to complicated “steady states.” Signal and contrast behavior can be described graphically and mathematically, and depends strongly on the type of spoiling: fully balanced (no spoiling), gradient spoiling, or RF-spoiling. These spoiling options trade off between high signal and pure T1 contrast while the flip angle also affects image contrast in all cases, both of which can be demonstrated theoretically and in image examples. As with spin-echo sequences, magnetization preparation can be added to gradient-echo sequences to alter image contrast. Gradient echo sequences are widely used for numerous applications such as 3D perfusion imaging, functional MRI, cardiac imaging and MR angiography. PMID:23097185

  5. Echo particle image velocimetry.

    PubMed

    DeMarchi, Nicholas; White, Christopher

    2012-12-27

    The transport of mass, momentum, and energy in fluid flows is ultimately determined by spatiotemporal distributions of the fluid velocity field.(1) Consequently, a prerequisite for understanding, predicting, and controlling fluid flows is the capability to measure the velocity field with adequate spatial and temporal resolution.(2) For velocity measurements in optically opaque fluids or through optically opaque geometries, echo particle image velocimetry (EPIV) is an attractive diagnostic technique to generate "instantaneous" two-dimensional fields of velocity.(3,4,5,6) In this paper, the operating protocol for an EPIV system built by integrating a commercial medical ultrasound machine(7) with a PC running commercial particle image velocimetry (PIV) software(8) is described, and validation measurements in Hagen-Poiseuille (i.e., laminar pipe) flow are reported. For the EPIV measurements, a phased array probe connected to the medical ultrasound machine is used to generate a two-dimensional ultrasound image by pulsing the piezoelectric probe elements at different times. Each probe element transmits an ultrasound pulse into the fluid, and tracer particles in the fluid (either naturally occurring or seeded) reflect ultrasound echoes back to the probe where they are recorded. The amplitude of the reflected ultrasound waves and their time delay relative to transmission are used to create what is known as B-mode (brightness mode) two-dimensional ultrasound images. Specifically, the time delay is used to determine the position of the scatterer in the fluid and the amplitude is used to assign intensity to the scatterer. The time required to obtain a single B-mode image, t, is determined by the time it take to pulse all the elements of the phased array probe. For acquiring multiple B-mode images, the frame rate of the system in frames per second (fps) = 1/δt. (See 9 for a review of ultrasound imaging.) For a typical EPIV experiment, the frame rate is between 20-60 fps

  6. Stellar Echo Imaging of Exoplanets

    NASA Technical Reports Server (NTRS)

    Mann, Chris; Lerch, Kieran; Lucente, Mark; Meza-Galvan, Jesus; Mitchell, Dan; Ruedin, Josh; Williams, Spencer; Zollars, Byron

    2016-01-01

    All stars exhibit intensity fluctuations over several timescales, from nanoseconds to years. These intensity fluctuations echo off bodies and structures in the star system. We posit that it is possible to take advantage of these echoes to detect, and possibly image, Earth-scale exoplanets. Unlike direct imaging techniques, temporal measurements do not require fringe tracking, maintaining an optically-perfect baseline, or utilizing ultra-contrast coronagraphs. Unlike transit or radial velocity techniques, stellar echo detection is not constrained to any specific orbital inclination. Current results suggest that existing and emerging technology can already enable stellar echo techniques at flare stars, such as Proxima Centauri, including detection, spectroscopic interrogation, and possibly even continent-level imaging of exoplanets in a variety of orbits. Detection of Earth-like planets around Sun-like stars appears to be extremely challenging, but cannot be fully quantified without additional data on micro- and millisecond-scale intensity fluctuations of the Sun. We consider survey missions in the mold of Kepler and place preliminary constraints on the feasibility of producing 3D tomographic maps of other structures in star systems, such as accretion disks. In this report we discuss the theory, limitations, models, and future opportunities for stellar echo imaging.

  7. Commissioning the Echo-Seeding Experiment Echo-7 at SLAC

    SciTech Connect

    Weathersby, S.a E.Colby; Dunning, M.; Gilevich, S.; Hast, C.; Jobe, K.; McCormick, D.; Nelson, J.; Raubenheimer, T.O.; Soong, K.; Stupakov, G.; Szalata, Z.; Walz, D.; Woodley, M.; Xiang, D.; Pernet, P-L.; /Ecole Polytechnique, Lausanne

    2011-06-02

    ECHO-7 is a proof-of-principle echo-enabled harmonic generation (EEHG) FEL experiment in the Next Linear Collider Test Accelerator (NLCTA) at SLAC. The experiment is intended to test the EEHG principle at low electron beam energy, 120 MeV, and determine the sensitivities and limitations to understand the expected performance at the higher energy scales and harmonic numbers required for x-ray FELs. In this paper we present the experimental results from the commissioning run of the completed experimental setup which started in April 2010.

  8. Photonic crystal light source

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu; Bur, James A.

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  9. Mechanochromic Fibers with Structural Color.

    PubMed

    Li, Houpu; Sun, Xuemei; Peng, Huisheng

    2015-12-21

    Responsive photonic crystals have been widely developed to realize tunable structural colors by manipulating the flow of light. Among them, mechanochromic photonic crystals attract increasing attention due to the easy operation, high safety and broad applications. Recently, mechanochromic photonic crystal fibers were proposed to satisfy the booming wearable smart textile market. In this Concept, the fundamental mechanism, fabrication, and recent progress on mechanochromic photonic crystals, especially in fiber shape, are summarized to represent a new direction in sensing and displaying.

  10. Fluid echoes in a pure electron plasma.

    PubMed

    Yu, J H; O'Neil, T M; Driscoll, C F

    2005-01-21

    Experimental observations of diocotron wave echoes on a magnetized electron column are reported, representing Kelvin wave echoes on a rotating near-ideal fluid. The echoes occur by reversal of an inviscid wave damping process, and the phase-space mixing and unmixing are directly imaged. The basic echo characteristics agree with a simple nonlinear ballistic theory. At late times, the echo is degraded, and the maximal observed echo times agree with a theory of electron-electron collisions acting on separately evolving velocity classes.

  11. Ultrafast optical spin echo in a single quantum dot

    NASA Astrophysics Data System (ADS)

    Press, David; de Greve, Kristiaan; McMahon, Peter L.; Ladd, Thaddeus D.; Friess, Benedikt; Schneider, Christian; Kamp, Martin; Höfling, Sven; Forchel, Alfred; Yamamoto, Yoshihisa

    2010-06-01

    Many proposed photonic quantum networks rely on matter qubits to serve as memory elements. The spin of a single electron confined in a semiconductor quantum dot forms a promising matter qubit that may be interfaced with a photonic network. Ultrafast optical spin control allows gate operations to be performed on the spin within a picosecond timescale, orders of magnitude faster than microwave or electrical control. One obstacle to storing quantum information in a single quantum dot spin is the apparent nanosecond-timescale dephasing due to slow variations in the background nuclear magnetic field. Here we use an ultrafast, all-optical spin echo technique to increase the decoherence time of a single quantum dot electron spin from nanoseconds to several microseconds. The ratio of decoherence time to gate time exceeds 105, suggesting strong promise for future photonic quantum information processors and repeater networks.

  12. Facility Search Criteria Help | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides powerful search capabilities offering more than 100 search criteria to target your results. Use the ECHO to search compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide.

  13. Nuclear quadrupole resonance echoes from hexamethylenetetramine.

    PubMed

    Ota, Go; Itozaki, Hideo

    2006-10-01

    We investigated the echo phenomenon of nuclear quadrupole resonance (NQR) from hexamethylenetetramine (HMT). We detected the pure NQR echo signal of HMT with a short pulse interval. The intensity of the echo signal increased as the pulse interval time was decreased. We observed that a clean echo signal was generated even when the pulse interval was shorter than the decay time constant T(2)(*). Since the short interval time gives a strong echo, our result insists that shorter interval time is preferred for the NQR detection.

  14. Two-color multiphoton emission from nanotips

    NASA Astrophysics Data System (ADS)

    Cheng-Wei Huang, Wayne; Becker, Maria; Beck, Joshua; Batelaan, Herman

    2017-02-01

    Two-color multiphoton emission from polycrystalline tungsten nanotips has been demonstrated using two-color laser fields. The two-color photoemission is assisted by a three-photon multicolor quantum channel, which leads to a twofold increase in quantum efficiency. Weak-field control of two-color multiphoton emission was achieved by changing the efficiency of the quantum channel with pulse delay. The result of this study complements two-color tunneling photoemission in strong fields, and has potential applications for nanowire-based photonic devices. Moreover, the demonstrated two-color multiphoton emission may be important for realizing ultrafast spin-polarized electron sources via optically injected spin current.

  15. Echo-Enabled Harmonic Generation

    SciTech Connect

    Stupakov, Gennady; /SLAC

    2012-06-28

    A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.

  16. Color Blindness

    MedlinePlus

    ... rose in full bloom. If you have a color vision defect, you may see these colors differently than most people. There are three main kinds of color vision defects. Red-green color vision defects are the most ...

  17. A radar-echo model for Mars

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.; Moore, H. J.

    1990-01-01

    Researchers developed a radar-echo model for Mars based on 12.6 cm continuous wave radio transmissions backscattered from the planet. The model broadly matches the variations in depolarized and polarized total radar cross sections with longitude observed by Goldstone in 1986 along 7 degrees S. and yields echo spectra that are generally similiar to the observed spectra. Radar map units in the model include an extensive cratered uplands unit with weak depolarized echo cross sections, average thermal inertias, moderate normal refelectivities, and moderate rms slopes; the volcanic units of Tharsis, Elysium, and Amazonis regions with strong depolarized echo cross sections, low thermal inertia, low normal reflectivities, and large rms slopes; and the northern planes units with moderate to strong depolarized echo cross sections, moderate to very high thermal inertias, moderate to large normal reflectivities, and moderate rms slopes. The relevance of the model to the interpretation of radar echoes from Mars is discussed.

  18. Is Echo a complex adaptive system?

    PubMed

    Smith, R M; Bedau, M A

    2000-01-01

    We evaluate whether John Holland's Echo model exemplifies his theory of complex adaptive systems. After reviewing Holland's theory of complex adaptive systems and describing his Escho model, we describe and explain the characteristic evolutionary behavior observed in a series of Echo model runs. We conclude that Echo lacks the diversity of hierarchically organized aggregates that typify complex adaptive systems, and we explore possible explanations for this failure.

  19. The Echoes of Earth Science

    NASA Technical Reports Server (NTRS)

    2006-01-01

    NASA s Earth Observing System Data and Information System (EOSDIS) acquires, archives, and manages data from all of NASA s Earth science satellites, for the benefit of the Space Agency and for the benefit of others, including local governments, first responders, the commercial remote sensing industry, teachers, museums, and the general public. EOSDIS is currently handling an extraordinary amount of NASA scientific data. To give an idea of the volume of information it receives, NASA s Terra Earth-observing satellite, just one of many NASA satellites sending down data, sends it hundreds of gigabytes a day, almost as much data as the Hubble Space Telescope acquires in an entire year, or about equal to the amount of information that could be found in hundreds of pickup trucks filled with books. To make EOSDIS data completely accessible to the Earth science community, NASA teamed up with private industry in 2000 to develop an Earth science "marketplace" registry that lets public users quickly drill down to the exact information they need. It also enables them to publish their research and resources alongside of NASA s research and resources. This registry is known as the Earth Observing System ClearingHOuse, or ECHO. The charter for this project focused on having an infrastructure completely independent from EOSDIS that would allow for more contributors and open up additional data access options. Accordingly, it is only fitting that the term ECHO is more than just an acronym; it represents the functionality of the system in that it can echo out and create interoperability among other systems, all while maturing with time as industry technologies and standards change and improve.

  20. Project Echo: Antenna Steering System

    NASA Technical Reports Server (NTRS)

    Klahn, R.; Norton, J. A.; Githens, J. A.

    1961-01-01

    The Project Echo communications experiment employed large, steerable,transmitting and receiving antennas at the ground terminals. It was necessary that these highly directional antennas be continuously and accurately pointed at the passing satellite. This paper describes a new type of special purpose data converter for directing narrow-beam communication antennas on the basis of predicted information. The system is capable of converting digital input data into real-time analog voltage commands with a dynamic accuracy of +/- 0.05 degree, which meets the requirements of the present antennas.

  1. Performance Considerations for the SIMPL Single Photon, Polarimetric, Two-Color Laser Altimeter as Applied to Measurements of Forest Canopy Structure and Composition

    NASA Technical Reports Server (NTRS)

    Dabney, Philip W.; Harding, David J.; Valett, Susan R.; Vasilyev, Aleksey A.; Yu, Anthony W.

    2012-01-01

    The Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) is a multi-beam, micropulse airborne laser altimeter that acquires active and passive polarimetric optical remote sensing measurements at visible and near-infrared wavelengths. SIMPL was developed to demonstrate advanced measurement approaches of potential benefit for improved, more efficient spaceflight laser altimeter missions. SIMPL data have been acquired for wide diversity of forest types in the summers of 2010 and 2011 in order to assess the potential of its novel capabilities for characterization of vegetation structure and composition. On each of its four beams SIMPL provides highly-resolved measurements of forest canopy structure by detecting single-photons with 15 cm ranging precision using a narrow-beam system operating at a laser repetition rate of 11 kHz. Associated with that ranging data SIMPL provides eight amplitude parameters per beam unlike the single amplitude provided by typical laser altimeters. Those eight parameters are received energy that is parallel and perpendicular to that of the plane-polarized transmit pulse at 532 nm (green) and 1064 nm (near IR), for both the active laser backscatter retro-reflectance and the passive solar bi-directional reflectance. This poster presentation will cover the instrument architecture and highlight the performance of the SIMPL instrument with examples taken from measurements for several sites with distinct canopy structures and compositions. Specific performance areas such as probability of detection, after pulsing, and dead time, will be highlighted and addressed, along with examples of their impact on the measurements and how they limit the ability to accurately model and recover the canopy properties. To assess the sensitivity of SIMPL's measurements to canopy properties an instrument model has been implemented in the FLIGHT radiative transfer code, based on Monte Carlo simulation of photon transport. SIMPL data collected in 2010 over

  2. Color blindness

    MedlinePlus

    ... have trouble telling the difference between red and green. This is the most common type of color ... color blindness often have problems seeing reds and greens, too. The most severe form of color blindness ...

  3. Photon-photon collisions

    SciTech Connect

    Burke, D.L.

    1982-10-01

    Studies of photon-photon collisions are reviewed with particular emphasis on new results reported to this conference. These include results on light meson spectroscopy and deep inelastic e..gamma.. scattering. Considerable work has now been accumulated on resonance production by ..gamma gamma.. collisions. Preliminary high statistics studies of the photon structure function F/sub 2//sup ..gamma../(x,Q/sup 2/) are given and comments are made on the problems that remain to be solved.

  4. Solar Sail Model Validation from Echo Trajectories

    NASA Technical Reports Server (NTRS)

    Heaton, Andrew F.; Brickerhoff, Adam T.

    2007-01-01

    The NASA In-Space Propulsion program has been engaged in a project to increase the technology readiness of solar sails. Recently, these efforts came to fruition in the form of several software tools to model solar sail guidance, navigation and control. Furthermore, solar sails are one of five technologies competing for the New Millennium Program Space Technology 9 flight demonstration mission. The historic Echo 1 and Echo 2 balloons were comprised of aluminized Mylar, which is the near-term material of choice for solar sails. Both spacecraft, but particularly Echo 2, were in low Earth orbits with characteristics similar to the proposed Space Technology 9 orbit. Therefore, the Echo balloons are excellent test cases for solar sail model validation. We present the results of studies of Echo trajectories that validate solar sail models of optics, solar radiation pressure, shape and low-thrust orbital dynamics.

  5. Fast magnetospheric echoes of energetic electron beams

    NASA Technical Reports Server (NTRS)

    Wilhelm, K.; Bernstein, W.; Kellogg, P. J.; Whalen, B. A.

    1983-01-01

    Electron beam experiments using rocket-borne instrumentation confirmed earlier observations of fast magnetospheric echoes of artificially injected energetic electrons. A total of 234 echoes were observed in a pitch angle range from 9 to 110 deg at energies of 1.87 and 3.90 keV. Of these, 102 echoes could unambiguously be identified with known accelerator operations at 2, 4 or 8 keV energy and highest current levels resulting in the determination of transit times of typically 300 to 400 ms. In most cases, when echoes were present in both energy channels, the higher energy electrons led the lower energy ones by 50 to 70 ms. Adiabatic theory applied to these observations yields a reflection height of 3000 to 4000 km. The injection process is discussed as the strong beam-plasma interaction that occurred near the electron accelerator appears to be instrumental in generating the source of heated electrons required for successful echo detection.

  6. Pulse-Echo Ultrasonic Imaging Method for Eliminating Sample Thickness Variation Effects

    NASA Technical Reports Server (NTRS)

    Roth, Don J. (Inventor)

    1997-01-01

    A pulse-echo, immersion method for ultrasonic evaluation of a material which accounts for and eliminates nonlevelness in the equipment set-up and sample thickness variation effects employs a single transducer and automatic scanning and digital imaging to obtain an image of a property of the material, such as pore fraction. The nonlevelness and thickness variation effects are accounted for by pre-scan adjustments of the time window to insure that the echoes received at each scan point are gated in the center of the window. This information is input into the scan file so that, during the automatic scanning for the material evaluation, each received echo is centered in its time window. A cross-correlation function calculates the velocity at each scan point, which is then proportionalized to a color or grey scale and displayed on a video screen.

  7. Pulse-echo ultrasonic imaging method for eliminating sample thickness variation effects

    NASA Technical Reports Server (NTRS)

    Roth, Don J. (Inventor)

    1995-01-01

    A pulse-echo, immersion method for ultrasonic evaluation of a material is discussed. It accounts for and eliminates nonlevelness in the equipment set-up and sample thickness variation effects employs a single transducer, automatic scanning and digital imaging to obtain an image of a property of the material, such as pore fraction. The nonlevelness and thickness variation effects are accounted for by pre-scan adjusments of the time window to insure that the echoes received at each scan point are gated in the center of the window. This information is input into the scan file so that, during the automatic scanning for the material evaluation, each received echo is centered in its time window. A cross-correlation function calculates the velocity at each scan point, which is then proportionalized to a color or grey scale and displayed on a video screen.

  8. Antigravity Acts on Photons

    NASA Astrophysics Data System (ADS)

    Brynjolfsson, Ari

    2002-04-01

    Einstein's general theory of relativity assumes that photons don't change frequency as they move from Sun to Earth. This assumption is correct in classical physics. All experiments proving the general relativity are in the domain of classical physics. This include the tests by Pound et al. of the gravitational redshift of 14.4 keV photons; the rocket experiments by Vessot et al.; the Galileo solar redshift experiments by Krisher et al.; the gravitational deflection of light experiments by Riveros and Vucetich; and delay of echoes of radar signals passing close to Sun as observed by Shapiro et al. Bohr's correspondence principle assures that quantum mechanical theory of general relativity agrees with Einstein's classical theory when frequency and gravitational field gradient approach zero, or when photons cannot interact with the gravitational field. When we treat photons as quantum mechanical particles; we find that gravitational force on photons is reversed (antigravity). This modified theory contradicts the equivalence principle, but is consistent with all experiments. Solar lines and distant stars are redshifted in accordance with author's plasma redshift theory. These changes result in a beautiful consistent cosmology.

  9. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  10. Incorporating active-learning techniques into the photonics-related teaching in the Erasmus Mundus Master in "Color in Informatics and Media Technology"

    NASA Astrophysics Data System (ADS)

    Pozo, Antonio M.; Rubiño, Manuel; Hernández-Andrés, Javier; Nieves, Juan L.

    2014-07-01

    In this work, we present a teaching methodology using active-learning techniques in the course "Devices and Instrumentation" of the Erasmus Mundus Master's Degree in "Color in Informatics and Media Technology" (CIMET). A part of the course "Devices and Instrumentation" of this Master's is dedicated to the study of image sensors and methods to evaluate their image quality. The teaching methodology that we present consists of incorporating practical activities during the traditional lectures. One of the innovative aspects of this teaching methodology is that students apply the concepts and methods studied in class to real devices. For this, students use their own digital cameras, webcams, or cellphone cameras in class. These activities provide students a better understanding of the theoretical subject given in class and encourage the active participation of students.

  11. Bio-inspired variable structural color materials.

    PubMed

    Zhao, Yuanjin; Xie, Zhuoying; Gu, Hongcheng; Zhu, Cun; Gu, Zhongze

    2012-04-21

    Natural structural color materials, especially those that can undergo reversible changes, are attracting increasing interest in a wide variety of research fields. Inspired by the natural creatures, many elaborately nanostructured photonic materials with variable structural colors were developed. These materials have found important applications in switches, display devices, sensors, and so on. In this critical review, we will provide up-to-date research concerning the natural and bio-inspired photonic materials with variable structural colors. After introducing the variable structural colors in natural creatures, we will focus on the studies of artificial variable structural color photonic materials, including their bio-inspired designs, fabrications and applications. The prospects for the future development of these fantastic variable structural color materials will also be presented. We believe this review will promote the communications among biology, bionics, chemistry, optical physics, and material science (196 references).

  12. Diffusion weighted vertical gradient and spin echo.

    PubMed

    Engström, Mathias; Bammer, Roland; Skare, Stefan

    2012-12-01

    In this work, diffusion weighting and parallel imaging is combined with a vertical gradient and spin echo data readout. This sequence was implemented and evaluated on healthy volunteers using a 1.5 and a 3 T whole-body MR system. As the vertical gradient and spin echo trajectory enables a higher k-space velocity in the phase-encoding direction than single-shot echo planar imaging, the geometrical distortions are reduced. When combined with parallel imaging such as generalized autocalibrating partially parallel acquisition, the geometric distortions are reduced even further, while also keeping the minimum echo time reasonably low. However, this combination of a diffusion preparation and multiple refocusing pulses during the vertical gradient and spin echo readout, generally violates the Carr-Purcell-Meiboom-Gill condition, which leads to interferences between echo pathways. To suppress the stimulated echo pathway, refocusing pulses with a sharper slice profiles and an odd/even crusher variation scheme were implemented and evaluated. Being a single-shot acquisition technique, the reconstructed images are robust to rigid-body head motion and spatially varying brain motion, both of which are common sources of artifacts in diffusion MRI.

  13. Optomechanical analog of two-color electromagnetically induced transparency: Photon transmission through an optomechanical device with a two-level system

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Gu, Xiu; Liu, Yu-xi; Miranowicz, Adam; Nori, Franco

    2014-08-01

    Some optomechanical systems can be transparent to a probe field when a strong driving field is applied. These systems can provide an optomechanical analog of electromagnetically induced transparency (EIT). We study the transmission of a probe field through a hybrid optomechanical system consisting of a cavity and a mechanical resonator with a two-level system (qubit). The qubit might be an intrinsic defect inside the mechanical resonator, a superconducting artificial atom, or another two-level system. The mechanical resonator is coupled to the cavity field via radiation pressure and to the qubit via the Jaynes-Cummings interaction. We find that the dressed two-level system and mechanical phonon can form two sets of three-level systems. Thus, there are two transparency windows in the discussed system. We interpret this effect as an optomechanical analog of two-color EIT (or double EIT). We demonstrate how to switch between one and two EIT windows by changing the transition frequency of the qubit. We show that the absorption and dispersion of the system are mainly affected by the qubit-phonon coupling strength and the transition frequency of the qubit.

  14. Geometric spin echo under zero field

    PubMed Central

    Sekiguchi, Yuhei; Komura, Yusuke; Mishima, Shota; Tanaka, Touta; Niikura, Naeko; Kosaka, Hideo

    2016-01-01

    Spin echo is a fundamental tool for quantum registers and biomedical imaging. It is believed that a strong magnetic field is needed for the spin echo to provide long memory and high resolution, since a degenerate spin cannot be controlled or addressed under a zero magnetic field. While a degenerate spin is never subject to dynamic control, it is still subject to geometric control. Here we show the spin echo of a degenerate spin subsystem, which is geometrically controlled via a mediating state split by the crystal field, in a nitrogen vacancy centre in diamond. The demonstration reveals that the degenerate spin is protected by inherent symmetry breaking called zero-field splitting. The geometric spin echo under zero field provides an ideal way to maintain the coherence without any dynamics, thus opening the way to pseudo-static quantum random access memory and non-invasive biosensors. PMID:27193936

  15. Air Dashboard Help | ECHO | US EPA

    EPA Pesticide Factsheets

    The dashboards found on the Enforcement and Compliance History Online (ECHO) website are specialized to track both facility and agency performance as they relate to compliance with and enforcement of environmental standards under the Clean Air Act (CAA).

  16. Geometric spin echo under zero field

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Yuhei; Komura, Yusuke; Mishima, Shota; Tanaka, Touta; Niikura, Naeko; Kosaka, Hideo

    2016-05-01

    Spin echo is a fundamental tool for quantum registers and biomedical imaging. It is believed that a strong magnetic field is needed for the spin echo to provide long memory and high resolution, since a degenerate spin cannot be controlled or addressed under a zero magnetic field. While a degenerate spin is never subject to dynamic control, it is still subject to geometric control. Here we show the spin echo of a degenerate spin subsystem, which is geometrically controlled via a mediating state split by the crystal field, in a nitrogen vacancy centre in diamond. The demonstration reveals that the degenerate spin is protected by inherent symmetry breaking called zero-field splitting. The geometric spin echo under zero field provides an ideal way to maintain the coherence without any dynamics, thus opening the way to pseudo-static quantum random access memory and non-invasive biosensors.

  17. Data processing of records of meteoric echoes

    NASA Astrophysics Data System (ADS)

    Dolinský, P.

    2016-01-01

    The data obtained in the period from 4 November 2014 to 31 July 2014 by our receiving and recording system was statistically processed. The system records meteoric echoes from the TV transmitter Lviv 49.739583 MHz (N49.8480° E24.0369°, Ukraine) using a 4-element Yagi antenna with horizontal polarization (elevation of 0° and azimuth of 60°), receiver ICOM R-75 in the CW mode, and a computer with a recording using HROFFT v1.0.0f. The main goal was to identify weak showers in these data. Mayor or strong showers are visible without processing (referred at IMC2015, Mistelbach). To find or to identify weaker showers is more difficult. Not all echoes are meteoric echoes, but also ionospheric echoes or lightning disturbances are present.

  18. MEASUREMENT OF TRANSVERSE ECHOES IN RHIC.

    SciTech Connect

    FISCHER, W.; SATOGATA, T.; TOMAS. R.

    2005-05-16

    Beam echoes are a very sensitive method to measure diffusion, and longitudinal echo measurements were performed in a number of machines. In RHIC, for the first time, a transverse beam echo was observed after applying a dipole kick followed by a quadrupole .kick. After application of the dipole kick, the dipole moment decohered completely due to lattice nonlinearities. When a quadrupole kick is applied at time {tau} after the dipole kick, the beam re-cohered at time 2{tau} thus showing an echo response. We describe the experimental setup and measurement results. In the measurements the dipole and quadrupole kick amplitudes, amplitude dependent tune shift, and the time between dipole and quadrupole kick were varied. In addition, measurements were taken with gold bunches of different intensities. These should exhibit different transverse diffusion rates due to intra-beam scattering.

  19. Hazardous Waste Dashboard Help | ECHO | US EPA

    EPA Pesticide Factsheets

    The dashboards found on the Enforcement and Compliance History Online (ECHO) website are specialized to track both facility and agency performance as they relate to compliance with and enforcement of environmental standards under the Resource Conservation and Recovery Act (RCRA).

  20. Water Dashboard Help | ECHO | US EPA

    EPA Pesticide Factsheets

    The dashboards found on the Enforcement and Compliance History Online (ECHO) website are specialized to track both facility and agency performance as they relate to compliance with and enforcement of environmental standards under the Clean Water Act (CWA).

  1. Estimation of Characteristics of Echo Envelope Using RF Echo Signal from the Liver

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tadashi; Hachiya, Hiroyuki; Kamiyama, Naohisa; Ikeda, Kazuki; Moriyasu, Norifumi

    2001-05-01

    To realize quantitative diagnosis of liver cirrhosis, we have been analyzing the probability density function (PDF) of echo amplitude using B-mode images. However, the B-mode image is affected by the various signal and image processing techniques used in the diagnosis equipment, so a detailed and quantitative analysis is very difficult. In this paper, we analyze the PDF of echo amplitude using RF echo signal and B-mode images of normal and cirrhotic livers, and compare both results to examine the validity of the RF echo signal.

  2. Drinking Water Dashboard Help | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  3. Frequently Asked Questions | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  4. Facility Search - All Data | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  5. Facility Search - Drinking Water | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  6. Detailed Facility Report | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

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    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  8. Facility Search - Air | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  9. Facility Search - Water | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  10. About the Data | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  11. Enforcement Case Search | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  12. Search Results Help - Air | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  13. Air Pollutant Report Help | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  14. Analyze Trends: State Hazardous Waste Dashboard | ECHO ...

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  15. Corporate Compliance Screener | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  16. Enforcement Case Search Help | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  17. Facility Search Results | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  18. Corporate Compliance Screener Help | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  19. Color realism and color science.

    PubMed

    Byrne, Alex; Hilbert, David R

    2003-02-01

    The target article is an attempt to make some progress on the problem of color realism. Are objects colored? And what is the nature of the color properties? We defend the view that physical objects (for instance, tomatoes, radishes, and rubies) are colored, and that colors are physical properties, specifically, types of reflectance. This is probably a minority opinion, at least among color scientists. Textbooks frequently claim that physical objects are not colored, and that the colors are "subjective" or "in the mind." The article has two other purposes: First, to introduce an interdisciplinary audience to some distinctively philosophical tools that are useful in tackling the problem of color realism and, second, to clarify the various positions and central arguments in the debate. The first part explains the problem of color realism and makes some useful distinctions. These distinctions are then used to expose various confusions that often prevent people from seeing that the issues are genuine and difficult, and that the problem of color realism ought to be of interest to anyone working in the field of color science. The second part explains the various leading answers to the problem of color realism, and (briefly) argues that all views other than our own have serious difficulties or are unmotivated. The third part explains and motivates our own view, that colors are types of reflectances and defends it against objections made in the recent literature that are often taken as fatal.

  20. Entropy, color, and color rendering.

    PubMed

    Price, Luke L A

    2012-12-01

    The Shannon entropy [Bell Syst. Tech J.27, 379 (1948)] of spectral distributions is applied to the problem of color rendering. With this novel approach, calculations for visual white entropy, spectral entropy, and color rendering are proposed, indices that are unreliant on the subjectivity inherent in reference spectra and color samples. The indices are tested against real lamp spectra, showing a simple and robust system for color rendering assessment. The discussion considers potential roles for white entropy in several areas of color theory and psychophysics and nonextensive entropy generalizations of the entropy indices in mathematical color spaces.

  1. Color Algebras

    NASA Technical Reports Server (NTRS)

    Mulligan, Jeffrey B.

    2017-01-01

    A color algebra refers to a system for computing sums and products of colors, analogous to additive and subtractive color mixtures. We would like it to match the well-defined algebra of spectral functions describing lights and surface reflectances, but an exact correspondence is impossible after the spectra have been projected to a three-dimensional color space, because of metamerism physically different spectra can produce the same color sensation. Metameric spectra are interchangeable for the purposes of addition, but not multiplication, so any color algebra is necessarily an approximation to physical reality. Nevertheless, because the majority of naturally-occurring spectra are well-behaved (e.g., continuous and slowly-varying), color algebras can be formulated that are largely accurate and agree well with human intuition. Here we explore the family of algebras that result from associating each color with a member of a three-dimensional manifold of spectra. This association can be used to construct a color product, defined as the color of the spectrum of the wavelength-wise product of the spectra associated with the two input colors. The choice of the spectral manifold determines the behavior of the resulting system, and certain special subspaces allow computational efficiencies. The resulting systems can be used to improve computer graphic rendering techniques, and to model various perceptual phenomena such as color constancy.

  2. Color Facsimile.

    DTIC Science & Technology

    1995-02-01

    modification of existing JPEG compression and decompression software available from Independent JPEG Users Group to process CIELAB color images and to use...externally specificed Huffman tables. In addition a conversion program was written to convert CIELAB color space images to red, green, blue color space

  3. Seeing Color

    ERIC Educational Resources Information Center

    Texley, Juliana

    2005-01-01

    Colors are powerful tools for engaging children, from the youngest years onward. We hang brightly patterned mobiles above their cribs and help them learn the names of colors as they begin to record their own ideas in pictures and words. Colors can also open the door to an invisible world of electromagnetism, even when children can barely imagine…

  4. Color of the ocean.

    PubMed

    Plass, G N; Humphreys, T J; Kattawar, G W

    1978-05-01

    The color of the ocean is calculated from a model that realistically takes into account the various types of scattering and absorption events that occur in both the atmosphere and ocean. Solar photons are followed through the atmosphere and into the ocean by a Monte Carlo technique. The reflection and refraction at the ocean surface are included in the calculation. The upward and downward flux is calculated at several different heights in the atmosphere, at thirteen different wavelengths from 0.4 mum to 0.7 mum. These results are compared with two approximate theories: (1) one-dimensional; (2) single scattering. The first of these theories gives results which are accurate within 10% in most cases and are easy to calculate. The chromaticity coordinates as well as the dominant wavelength and purity of the color are calculated from the Monte Carlo results for the variation of upward flux with wavelength. The ocean color near the horizon is almost entirely determined by the color of the sky reflected by the ocean surface. The upwelling light from the ocean can be observed near the nadir if precautions are taken to exclude as much light as possible reflected from the ocean surface. The color of this upwelling light from the ocean contains much information about the hydrosol, chlorophyll, and yellow substance amounts in the ocean water. The model calculations show how the ocean color changes from a deep blue of high purity for relatively pure water to a greenish blue and then to green of low purity as the cholorphyll and yellow substance amounts increase. Further increases in these substances cause the color to change to yellow green of a higher purity. A large increase in the hydrosol amount usually causes a marked decrease in the purity of the color.

  5. Color Categories and Color Appearance

    ERIC Educational Resources Information Center

    Webster, Michael A.; Kay, Paul

    2012-01-01

    We examined categorical effects in color appearance in two tasks, which in part differed in the extent to which color naming was explicitly required for the response. In one, we measured the effects of color differences on perceptual grouping for hues that spanned the blue-green boundary, to test whether chromatic differences across the boundary…

  6. Color Terms and Color Concepts

    ERIC Educational Resources Information Center

    Davidoff, Jules

    2006-01-01

    In their lead articles, both Kowalski and Zimiles (2006) and O'Hanlon and Roberson (2006) declare a general relation between color term knowledge and the ability to conceptually represent color. Kowalski and Zimiles, in particular, argue for a priority for the conceptual representation in color term acquisition. The complexities of the interaction…

  7. Fast magnetospheric echoes of energetic electron beams

    NASA Technical Reports Server (NTRS)

    Wilhelm, K.; Bernstein, W.; Kellogg, P. J.; Whalen, B. A.

    1985-01-01

    Electron beam experiments using rocketborne instrumentation have confirmed earlier observations of fast magnetospheric echoes of artificially injected energetic electrons. A total of 234 echoes have been observed in a pitch angle range from 9 to 110 deg at energies of 1.87 and 3.90 keV. Out of this number, 95 echoes could unambiguously be identified with known accelerator operations at 2-, 4-, or 8-keV energy and highest current levels resulting in the determination of transit times of typically 300 to 400 ms. In most cases, when echoes were present in both energy channels, the higher-energy electrons led the lower-energy ones by 50 to 70 ms. Adiabatic theory applied to these observations yields a reflection height of 3000 to 4000 km. An alternative interpretation is briefly examined, and its relative merit in describing the observations is evaluated. The injection process is discussed in some detail as the strong beam-plasma interaction that occurred near the electron accelerator appears to be instrumental in generating the source of heated electrons required for successful echo detection for both processes.

  8. Light Echoes of Galactic Explosions and Eruptions

    NASA Astrophysics Data System (ADS)

    Rest, Armin; Bianco, Federica; Chornock, Ryan; Foley, Ryan; Matheson, Thomas; Olsen, Knut; Prieto, Jose Luis; Sinnott, Brendan; Smith, Chris; Smith, Nathan; Welch, Doug

    2013-02-01

    We propose to continue our search for the first light echoes (LEs) associated with historical Galactic supernovae and LBV outbursts: SN 1006, Kepler's SN, RCW 86, Crab Nebula, and P Cygni. In previously granted NOAO time, we have discovered light echoes of three ancient SNe in the LMC as well as from the historic SN events of Cas A and Tycho [2, 3], which allowed their spectroscopic classification [6, 7, 10] and 3D spectroscopy [8, 9]. Most recently, we discovered light echoes of the mid-19th-century Great Eruption of eta Carinae using CTIO 4m Mosaic images [11]. Subsequent spectroscopic follow-up of Eta Carinae revealed that its outburst spectral type was most similar to those of G-type supergiants, rather than reported LBV outburst spectral types of F-type (or earlier) [11]. We propose to continue our search for light echoes of the remaining historical events. With DECam, we have a 10-15 fold improvement in efficiency over the retired Mosaic camera, which allows us to cover the bigger search areas of most of the remaining targets. The study of scattered-light echoes from these Galactic supernovae and eruptions will give us the opportunity to directly compare the original outburst and its current remnant, and in favorable cases (like Eta Carinae), it provides a three-dimensional view of the event and/or a spectral time series.

  9. Classical Acoustic Echoes in Model Glasses

    NASA Astrophysics Data System (ADS)

    Burton, Justin; Nagel, Sidney

    2013-03-01

    For the last 40 years, the low-temperature excitations in glasses have traditionally been explained in terms of a distribution of dilute, two-level quantum states that are created by clusters of particles tunneling between two nearly degenerate ground states. Strong evidence for this model has come from ultrasonic saturation effects and acoustic echoes observed in experiments. Recently, a classical analysis of vibrational modes in model glasses has shown that at low frequencies, the modes are quasi-localized and highly anharmonic. Using molecular dynamics simulations, we show that this anharmonicity can produce an acoustic echo due to the shift in the mode frequency with increasing amplitude. We observe this both in jammed packings of spherical particles with finite-range, Hertzian repulsions, and in model glasses interacting with a Lennard-Jones potential. In contrast to pulse echoes in two-level systems, a distinguishing feature of these ``anharmonic echoes'' is the appearance of multiple echoes after two excitation pulses, a feature also observed in experiments.

  10. Color terms and color concepts.

    PubMed

    Davidoff, Jules

    2006-08-01

    In their lead articles, both Kowalski and Zimiles (2006) and O'Hanlon and Roberson (2006) declare a general relation between color term knowledge and the ability to conceptually represent color. Kowalski and Zimiles, in particular, argue for a priority for the conceptual representation in color term acquisition. The complexities of the interaction are taken up in the current commentary, especially with regard to the neuropsychological evidence. Data from aphasic patients also argue for a priority for abstract thought, but nevertheless it may still be that the use of color terms is the only way in which to form color categories even if both linguistic and attentional factors play an important role.

  11. Natural photonic crystals

    NASA Astrophysics Data System (ADS)

    Vigneron, Jean Pol; Simonis, Priscilla

    2012-10-01

    Photonic structures appeared in nature several hundred millions years ago. In the living world, color is used for communication and this important function strongly impacts the individual chances of survival as well as the chances to reproduce. This has a statistical influence on species populations. Therefore, because they are involved in evolution, natural color-generating structures are - from some point of view - highly optimized. In this short review, a survey is presented of the development of natural photonic crystal-type structures occurring in insects, spiders, birds, fishes and other marine animals, in plants and more, from the standpoint of light-waves propagation. One-, two-, and three-dimensional structures will be reviewed with selected examples.

  12. Color Analysis

    NASA Astrophysics Data System (ADS)

    Wrolstad, Ronald E.; Smith, Daniel E.

    Color, flavor, and texture are the three principal quality attributes that determine food acceptance, and color has a far greater influence on our judgment than most of us appreciate. We use color to determine if a banana is at our preferred ripeness level, and a discolored meat product can warn us that the product may be spoiled. The marketing departments of our food corporations know that, for their customers, the color must be "right." The University of California Davis scorecard for wine quality designates four points out of 20, or 20% of the total score, for color and appearance (1). Food scientists who establish quality control specifications for their product are very aware of the importance of color and appearance. While subjective visual assessment and use of visual color standards are still used in the food industry, instrumental color measurements are extensively employed. Objective measurement of color is desirable for both research and industrial applications, and the ruggedness, stability, and ease of use of today's color measurement instruments have resulted in their widespread adoption.

  13. Processing of Color Words Activates Color Representations

    ERIC Educational Resources Information Center

    Richter, Tobias; Zwaan, Rolf A.

    2009-01-01

    Two experiments were conducted to investigate whether color representations are routinely activated when color words are processed. Congruency effects of colors and color words were observed in both directions. Lexical decisions on color words were faster when preceding colors matched the color named by the word. Color-discrimination responses…

  14. Echo Mapping of Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Peterson, B. M.; Horne, K.

    2004-01-01

    Echo mapping makes use of the intrinsic variability of the continuum source in active galactic nuclei to map out the distribution and kinematics of line-emitting gas from its light travel time-delayed response to continuum changes. Echo mapping experiments have yielded sizes for the broad line-emitting region in about three dozen AGNs. The dynamics of the line-emitting gas seem to be dominated by the gravity of the central black hole, enabling measurement of the black-hole masses in AGNs. We discuss requirements for future echo-mapping experiments that will yield the high quality velocity-delay maps of the broad-line region that are needed to determine its physical nature.

  15. Transient Loschmidt echo in quenched Ising chains

    NASA Astrophysics Data System (ADS)

    Lupo, Carla; Schiró, Marco

    2016-07-01

    We study the response to sudden local perturbations of highly excited quantum Ising spin chains. The key quantity encoding this response is the overlap between time-dependent wave functions, which we write as a transient Loschmidt Echo. Its asymptotics at long time differences contain crucial information about the structure of the highly excited nonequilibrium environment induced by the quench. We compute the echo perturbatively for a weak local quench but for arbitrarily large global quench, using a cumulant expansion. Our perturbative results suggest that the echo decays exponentially, rather than power law as in the low-energy orthogonality catastrophe, a further example of quench-induced decoherence already found in the case of quenched Luttinger liquids. The emerging decoherence scale is set by the strength of the local potential and the bulk excitation energy.

  16. Search Results Help - Water | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available. Search Results Help explains how to navigate the search results page and describes the data presented.

  17. Rationale and Design of the Echocardiographic Study of Hispanics / Latinos (ECHO-SOL)

    PubMed Central

    Rodriguez, Carlos J.; Dharod, Ajay; Allison, Matthew A.; Shah, Sanjiv J.; Hurwitz, Barry; Bangdiwala, Shrikant I.; Gonzalez, Franklyn; Kitzman, Dalane; Gillam, Linda; Spevack, Daniel; Dadhania, Rupal; Langdon, Sarah; Kaplan, Robert

    2015-01-01

    Background Information regarding the prevalence and determinants of cardiac structure and function (systolic and diastolic) among the various Hispanic background groups in the United States is limited. Methods and Results The Echocardiographic Study of Latinos (ECHO-SOL) ancillary study recruited 1,824 participants through a stratified-sampling process representative of the population-based Hispanic Communities Health Study – Study of Latinos (HCHS-SOL) across four sites (Bronx, NY; Chicago, Ill; San Diego, Calif; Miami, Fla). The HCHS-SOL baseline cohort did not include an echo exam. ECHO-SOL added the echocardiographic assessment of cardiac structure and function to an array of existing HCHS-SOL baseline clinical, psychosocial, and socioeconomic data and provides sufficient statistical power for comparisons among the Hispanic subgroups. Standard two-dimensional (2D) echocardiography protocol, including M-mode, spectral, color and tissue Doppler study was performed. The main objectives were to: 1) characterize cardiac structure and function and its determinants among Hispanics and Hispanic subgroups; and 2) determine the contributions of specific psychosocial factors (acculturation and familismo) to cardiac structure and function among Hispanics. Conclusion We describe the design, methods and rationale of currently the largest and most comprehensive study of cardiac structure and function exclusively among US Hispanics. ECHO-SOL aims to enhance our understanding of Hispanic cardiovascular health as well as help untangle the relative importance of Hispanic subgroup heterogeneity and sociocultural factors on cardiac structure and function. (Ethn Dis. 2015;25[2]:180–186) PMID:26118146

  18. Quantum Color

    ScienceCinema

    Lincoln, Don

    2016-07-20

    The idea of electric charges and electricity in general is a familiar one to the science savvy viewer. However, electromagnetism is but one of the four fundamental forces and not the strongest one. The strongest of the fundamental forces is called the strong nuclear force and it has its own associated charge. Physicists call this charge “color” in analogy with the primary colors, although there is no real connection with actual color. In this video, Fermilab’s Dr. Don Lincoln explains why it is that we live in a colorful world.

  19. Polar Color

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 3 May 2004 This nighttime visible color image was collected on January 1, 2003 during the Northern Summer season near the North Polar Troughs.

    This daytime visible color image was collected on September 4, 2002 during the Northern Spring season in Vastitas Borealis. The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    Image information: VIS instrument. Latitude 79, Longitude 346 East (14 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with

  20. Relationship between tornadoes and hook echoes on April 3, 1974

    NASA Technical Reports Server (NTRS)

    Forbes, G. S.

    1975-01-01

    Radar observations of tornado families occurring on April 3, 1974 are discussed. Of the 93 tornadoes included in the sample, 81% were associated with hook-like echoes with appendages at least 40 deg to the south of the echo movement. At least one tornado was associated with 62% of the hook-like echoes observed. All of the tornadoes with intensities of F 4 and F 5 were produced by hook-like echoes; the mean intensity of all tornadoes associated with this type of echo was F 3, while the mean intensity of the remaining tornadoes was F1. The tornadic hook-like echoes moved to the right of the non-tornadic echoes forming a tornado line in advance of the squall line. Some tornadoes were associated with 'spiral' echoes.

  1. On the reliability of hook echoes as tornado indicators

    NASA Technical Reports Server (NTRS)

    Forbes, G. S.

    1981-01-01

    A study of radar echoes associated with the tornadoes of the 3 April 1974 outbreak was performed to evaluate the usefulness of echo shape as an indicator of tornadic thunderstorms. The hook shape was usually successful in characterizing an echo as tornadic, with a false alarm rate of 16%. Because hook echoes were relatively rare, however, a less restrictive shape called distinctive was more successful at detecting tornadic thunderstorms, identifying 65% of the tornadic echoes. An echo had a distinctive shape if it possessed a marked appendage on its right rear flank or was in the shape of a spiral, comma or line echo wave pattern (LEWP). Characteristics of the distinctive echo are given.

  2. Asymmetric radar echo patterns from insects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Radar echoes from insects, birds, and bats in the atmosphere exhibit both symmetry and asymmetry in polarimetric patterns. Symmetry refers to similar magnitudes of polarimetric variables at opposite azimuths, and asymmetry relegates to differences in these magnitudes. Asymmetry can be due to diffe...

  3. Light Echoes of Galactic Explosions and Eruptions

    NASA Astrophysics Data System (ADS)

    Rest, Armin; Bianco, Federica; Chornock, Ryan; Foley, Ryan; Matheson, Thomas; Narayan, Gautham; Olsen, Knut; Prieto, Jose Luis; Smith, Chris; Smith, Nathan; Suntzeff, Nick; Welch, Doug; Zenteno, Alfredo

    2014-02-01

    We propose to continue our search for the first light echoes (LEs) associated with historical Galactic supernovae and LBV outbursts: SN 1006, Kepler's SN, RCW 86, Crab Nebula, and P Cygni. In previously granted NOAO time, we have discovered LEs of three ancient SNe in the LMC as well as from the historic SN events of Cas A and Tycho [2, 3], which allowed their spectroscopic classification [6, 7, 10] and 3D spectroscopy [8, 9]. Most recently, we discovered light echoes of the mid-19th-century Great Eruption of η Carinae using CTIO 4m Mosaic images [11]. Subsequent spectroscopic follow-up of Eta Carinae revealed that its outburst spectral type was most similar to those of G-type supergiants, rather than reported LBV outburst spectral types of F-type (or earlier) [11]. We propose to continue our search for light echoes of the remaining historical events. With DECam, we have a 10-15 fold improvement in efficiency over the retired CTIO-Mosaic camera, which allows us to cover the bigger search areas of most of the remaining targets. With the KPNO 4-m, we will observe fields too far north for CTIO/DECam. The study of scattered-light echoes from these Galactic supernovae and eruptions will give us the opportunity to directly compare the original outburst and its current remnant, and in favorable cases (like Eta Carinae), it provides a three-dimensional view of the event and/or a spectral time series.

  4. Data Entry Requirements | ECHO | US EPA

    EPA Pesticide Factsheets

    Data in ECHO are provided by authorized state, tribal, and local governments, and EPA Regional offices. Information is presented to help users understand where data are more complete. Many states voluntarily enter additional data that are not required; therefore, data completeness may vary widely from state to state.

  5. Choroidal osteoma: acoustic shadowing and reduplication echoes.

    PubMed

    Abramson, D H; Servodidio, C A; Poole, T A; Budinger, K

    1996-12-01

    A 27-year-old woman had a curious choroidal mass of 12 years duration in her right eye. Interesting ultrasonic findings of a choroidal osteoma, including acoustic shadowing and reduplication echoes on A-scan and B-scan are presented. Ophthalmic nurses can assist in performing ophthalmic examinations and in reinforcing regular follow-up examinations for these patients.

  6. An Evaluation of HF Ionospheric Backscatter Echoes

    DTIC Science & Technology

    1975-11-01

    regulated bj the following claaaiTlcaUone In order t’i aaf^uard proprietär) mior- matk in: CLASS l: GENERAL INFORMATION .\\\\ ailable ti i an] one on...km and were gen - tiallv spread in range (diffuse). The occurrence of the sunset echoes was relatively inde- pendent of magnetic activity. The

  7. State Comparative Maps Help | ECHO | US EPA

    EPA Pesticide Factsheets

    Comparative Maps in ECHO focus on environmental compliance and enforcement trends at a state and national level. Comparative maps provide a quick cross-country look at key environmental compliance and enforcement indicators. The maps link to dashboards that provide details by state/territory.

  8. AN ECHO OF SUPERNOVA 2008bk

    SciTech Connect

    Van Dyk, Schuyler D.

    2013-08-01

    I have discovered a prominent light echo around the low-luminosity Type II-plateau supernova (SN) 2008bk in NGC 7793, seen in archival images obtained with the Wide Field Channel of the Advanced Camera for Surveys on board the Hubble Space Telescope (HST). The echo is a partial ring, brighter to the north and east than to the south and west. The analysis of the echo I present suggests that it is due to the SN light pulse scattered by a sheet, or sheets, of dust located Almost-Equal-To 15 pc from the SN. The composition of the dust is assumed to be of standard Galactic diffuse interstellar grains. The visual extinction of the dust responsible for the echo is A{sub V} Almost-Equal-To 0.05 mag in addition to the extinction due to the Galactic foreground toward the host galaxy. That the SN experienced much less overall extinction implies that it is seen through a less dense portion of the interstellar medium in its environment. The late-time HST photometry of SN 2008bk also clearly demonstrates that the progenitor star has vanished.

  9. Color Metric.

    ERIC Educational Resources Information Center

    Illinois State Office of Education, Springfield.

    This booklet was designed to convey metric information in pictoral form. The use of pictures in the coloring book enables the more mature person to grasp the metric message instantly, whereas the younger person, while coloring the picture, will be exposed to the metric information long enough to make the proper associations. Sheets of the booklet…

  10. Preliminary Results of the Echo-Seeding Experiment ECHO-7 at SLAC

    SciTech Connect

    Xiang, D.; Colby, E.; Ding, Y.; Dunning, M.; Frederico, J.; Gilevich, S.; Hast, C.; Jobe, K.; McCormick, D.; Nelson, J.; Raubenheimer, T.O.; Soong, K.; Stupakov, G.; Szalata, Z.; Walz, D.; Weathersby, S.; Woodley, M.; Corlett, J.; Qiang, J.; Penn, G.; Prestemon, S.; /LBL, Berkeley /LPHE, Lausanne

    2010-06-15

    ECHO-7 is a proof-of-principle echo-enabled harmonic generation FEL experiment in the Next Linear Collider Test Accelerator (NLCTA) at SLAC. The experiment aims to generate coherent radiation at 318 nm and 227 nm, which are the 5th and 7th harmonic of the infrared seed laser. In this paper we present the preliminary results from the commissioning run of the completed experimental setup which started in April 2010.

  11. X-ray shout echoing through space

    NASA Astrophysics Data System (ADS)

    2004-01-01

    observatories around the world were pointing their instruments at this mysterious source in the sky, named GRB 031203, in the attempt to decipher its nature. Also ESA's X-ray observatory, XMM-Newton, joined the hunt and observed the source in detail, using its on-board European Photon Imaging Camera (EPIC). The fading X-ray emission from GRB 031203 - called the `afterglow' - is clearly seen in XMM-Newton's images. But much more stunning are the two rings, centred on the afterglow, which appear to expand thousand times faster than the speed of light. Dr. Simon Vaughan, of the University of Leicester, United Kingdom, leads an international team of scientists studying GRB 031203. He explains that these rings are what astronomers call an `echo'. They form when the X-rays from the distant gamma-ray burst shine on a layer of dust in our own Galaxy. "The dust scatters some of the X-rays, causing XMM-Newton to observe these rings, much in the same way as fog scatters the light from a car's headlights," said Vaughan. Although the afterglow is the brightest feature seen in XMM-Newton's images, the expanding echo is much more spectacular. "It is like a shout in a cathedral," Vaughan said. "The shout of the gamma-ray burst is louder, but the Galactic reverberation, seen as the rings, is much more beautiful." The rings seem to expand because the X-rays scattered by dust farther from the direction of GRB 031203 take longer to reach us than those hitting the dust closer to the line of sight. However, nothing can move faster than light. "This is precisely what we expect because of the finite speed of light," said Vaughan. "The rate of expansion that we see is just a visual effect." He and his colleagues explain that we see two rings because there are two thin sheets of dust between the source of the gamma-ray burst and Earth, one closer to us creating the wider ring and one further away where the smaller ring is formed. Since they know precisely at what speed the X-ray light travels in space

  12. Using cuttlefish ink as an additive to produce -non-iridescent structural colors of high color visibility.

    PubMed

    Zhang, Yafeng; Dong, Biqin; Chen, Ang; Liu, Xiaohan; Shi, Lei; Zi, Jian

    2015-08-26

    Non-iridescent structural colors of high color visibility are produced by amorphous photonic structures, in which -natural cuttlefish ink is used as an additive to break down the long-range order of the structures. The color hue and its spectral purity can be tuned by adjusting the diameter of the polystyrene (PS) spheres and the proportion of ink particles.

  13. The extraordinary radar echoes from Europa, Ganymede, and Callisto: A geological perspective

    USGS Publications Warehouse

    Ostro, S.J.; Shoemaker, E.M.

    1990-01-01

    This outline of plausible geologic explanations for the icy Galilean satellites' radar properties takes into consideration electromagnetic scattering models for the echoes, available empirical and theoretical information about regolith formation, and ice physics. The strange radar signatures arise because (1) ice is electrically different from silicates and/or (2) icy regoliths contain bulk-density (and hence refractive-index) structures absent within silicate regoliths. Ice's relatively high radar-frequency transparency compared with that of silicates permits longer photon path lengths, deeper radar sounding, and a greater number of scattering events. Consequently, scattering mechanisms that cannot contribute significantly to lunar echoes can dominate icy-satellite echoes. Possible phenomena unique to icy regoliths include (1) smoothing out of discontinuities between solid ejecta fragments and more porous surroundings under the action of thermal annealing to form refraction-scattering (RS) "lenses" and (2) formation of density enhancements in the shape of crater floors that result in RS and/or total internal reflection (TIR). In either case, high-order multiple scattering is more likely to be responsible for the echoes than low-order scattering. Radar/radio observations can constrain the order of the scattering and the scale of the structures responsible for the echoes but might not determine whether TIR or RS dominates the scattering. Multiwavelength investigations of the degree of correlation between radar properties and geologic terrain type should prove most useful, because inter- and intrasatellite variations in radar properties probably correspond to variations in ice purity, regolith thickness, and regolith thermal history and age. ?? 1990.

  14. About AGN ionization echoes, thermal echoes and ionization deficits in low-redshift Lyα blobs

    NASA Astrophysics Data System (ADS)

    Schirmer, Mischa; Malhotra, Sangeeta; Levenson, Nancy A.; Fu, Hai; Davies, Rebecca L.; Keel, William C.; Torrey, Paul; Bennert, Vardha N.; Pancoast, Anna; Turner, James E. H.

    2016-12-01

    We report the discovery of 14 Lyα blobs (LABs) at z ˜ 0.3, existing at least 4-7 billion years later in the Universe than all other LABs known. Their optical diameters are 20-70 kpc, and GALEX data imply Lyα luminosities of (0.4-6.3) × 1043 erg s-1. Contrary to high-z LABs, they live in low-density areas. They are ionized by AGN, suggesting that cold accretion streams as a power source must deplete between z = 2 and 0.3. We also show that transient AGN naturally explain the ionization deficits observed in many LABs. Their Lyα and X-ray fluxes decorrelate below ≲106 years because of the delayed escape of resonantly scattering Lyα photons. High Lyα luminosities do not require currently powerful AGN, independent of obscuration. Chandra X-ray data reveal intrinsically weak AGN, confirming the luminous optical nebulae as impressive ionization echoes. For the first time, we also report mid-infrared thermal echoes from the dusty tori. We conclude that the AGN have faded by three to four orders of magnitude within the last 104-5 years, leaving fossil UV, optical and thermal radiation behind. The host galaxies belong to the group of previously discovered Green Bean galaxies (GBs). Gemini optical imaging reveals smooth spheres, mergers, spectacular outflows and ionization cones. Because of their proximity and high flux densities, GBs are perfect targets to study AGN feedback, mode switching and the Lyα escape. The fully calibrated, co-added optical FITS images are publicly available.

  15. Diffusion-Weighted Imaging with Dual-Echo Echo-Planar Imaging for Better Sensitivity to Acute Stroke

    PubMed Central

    Holdsworth, S.J.; Yeom, K.W.; Antonucci, M.U.; Andre, J.B.; Rosenberg, J.; Aksoy, M.; Straka, M.; Fischbein, N.J.; Bammer, R.; Moseley, M.E.; Zaharchuk, G.; Skare, S.

    2015-01-01

    BACKGROUND AND PURPOSE Parallel imaging facilitates the acquisition of echo-planar images with a reduced TE, enabling the incorporation of an additional image at a later TE. Here we investigated the use of a parallel imaging–enhanced dual-echo EPI sequence to improve lesion conspicuity in diffusion-weighted imaging. MATERIALS AND METHODS Parallel imaging–enhanced dual-echo DWI data were acquired in 50 consecutive patients suspected of stroke at 1.5T. The dual-echo acquisition included 2 EPI for 1 diffusion-preparation period (echo 1 [TE = 48 ms] and echo 2 [TE = 105 ms]). Three neuroradiologists independently reviewed the 2 echoes by using the routine DWI of our institution as a reference. Images were graded on lesion conspicuity, diagnostic confidence, and image quality. The apparent diffusion coefficient map from echo 1 was used to validate the presence of acute infarction. Relaxivity maps calculated from the 2 echoes were evaluated for potential complementary information. RESULTS Echo 1 and 2 DWIs were rated as better than the reference DWI. While echo 1 had better image quality overall, echo 2 was unanimously favored over both echo 1 and the reference DWI for its high sensitivity in detecting acute infarcts. CONCLUSIONS Parallel imaging–enhanced dual-echo diffusion-weighted EPI is a useful method for evaluating lesions with reduced diffusivity. The long TE of echo 2 produced DWIs that exhibited superior lesion conspicuity compared with images acquired at a shorter TE. Echo 1 provided higher SNR ADC maps for specificity to acute infarction. The relaxivity maps may serve to complement information regarding blood products and mineralization. PMID:24763417

  16. Control of Quantum Echo and Bell State Swapping of Two Atomic Qubits in the Two-Mode Vacuum Field Environment

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Juan; Luo, An; Peng, Zhao-Hui; Zhou, Bing-Ju; Liu, Ming-Wei; Jia, Chun-Xia; Jiang, Chun-Lei

    2016-11-01

    We investigate quantum echo control and Bell state swapping for two atomic qubits (TAQs) coupling to two-mode vacuum cavity field (TMVCF) environment via two-photon resonance. We discuss the effect of initial entanglement factor 𝜃 and relative coupling strength R= g 1/ g 2 on quantum state fidelity of TAQs, and analyze the relation between three kinds of quantum entanglement( C( ρ a ), C( ρ f ), S( ρ a )) and quantum state fidelity, then reveal physical essence of quantum echo of TAQs. It is shown that in the identical coupling case R=1, periodic quantum echo of TAQs with π cycle is always produced, and the value of fidelity can be controlled by choosing appropriate 𝜃 and atom-filed interaction time. In the non-identical coupling case R≠1, quantum echoes with periods of π, 2 π and 4 π can be formed respectively by adjusting R. The characteristics of quantum echo results from the non-Markovianity of TMVCF environment, and then we propose Bell state swapping scheme between TAQs and two-mode cavity field.

  17. Quantum Color

    SciTech Connect

    Lincoln, Don

    2016-07-05

    The idea of electric charges and electricity in general is a familiar one to the science savvy viewer. However, electromagnetism is but one of the four fundamental forces and not the strongest one. The strongest of the fundamental forces is called the strong nuclear force and it has its own associated charge. Physicists call this charge “color” in analogy with the primary colors, although there is no real connection with actual color. In this video, Fermilab’s Dr. Don Lincoln explains why it is that we live in a colorful world.

  18. Intensity-Corrected Dual-Echo Echo-Planar Imaging (DE-EPI) for Improved Pediatric Brain Diffusion Imaging

    PubMed Central

    Straka, Matus; Iv, Michael; Moseley, Michael E.; Barnes, Patrick D.; Skare, Stefan

    2015-01-01

    Here we investigate the utility of a dual-echo Echo-Planar Imaging (DE-EPI) Diffusion Weighted Imaging (DWI) approach to improve lesion conspicuity in pediatric imaging. This method delivers two ‘echo images’ for one diffusion-preparation period. We also demonstrate how the echoes can be utilized to remove transmit/receive coil-induced and static magnetic field intensity modulations on both echo images, which often mimic pathology and thereby pose diagnostic challenges. DE-EPI DWI data were acquired in 18 pediatric patients with abnormal diffusion lesions, and 46 pediatric patient controls at 3T. Echo1 [TE = 45ms] and Echo2 [TE = 86ms] were corrected for signal intensity variation across the images by exploiting the images equivalent coil-sensitivity and susceptibility-induced modulations. Two neuroradiologists independently reviewed Echo1 and Echo2 and their intensity-corrected variants (cEcho1 and cEcho2) on a 7-point Likert scale, with grading on lesion conspicuity diagnostic confidence. The apparent diffusion coefficient (ADC) map from Echo1 was used to validate presence of true pathology. Echo2 was unanimously favored over Echo1 for its sensitivity for detecting acute brain injury, with a mean respective lesion conspicuity of 5.7/4.4 (p < 0.005) and diagnostic confidence of 5.1/4.3 (p = 0.025). cEcho2 was rated higher than cEcho1, with a mean respective lesion conspicuity of 5.5/4.3 (p < 0.005) and diagnostic confidence of 5.4/4.4 (p < 0.005). cEcho2 was favored over all echoes for its diagnostic reliability, particularly in regions close to the head coil. This work concludes that DE-EPI DWI is a useful alternative to conventional single-echo EPI DWI, whereby Echo2 and cEcho2 allows for improved lesion detection and overall higher diagnostic confidence. PMID:26069959

  19. Controlling the Two-Photon-Induced Photon Cascade Emission in a Gd3+/Tb3+-Codoped Glass for Multicolor Display

    PubMed Central

    Yuan, Mao-Hui; Fan, Hai-Hua; Li, Hui; Lan, Sheng; Tie, Shao-Long; Yang, Zhong-Min

    2016-01-01

    We reported the first observation of the two-photon-induced quantum cutting phenomenon in a Gd3+/Tb3+-codoped glass in which two photons at ~400 nm are simultaneously absorbed, leading to the cascade emission of three photons in the visible spectral region. The two-photon absorption induced by femtosecond laser pulses allows the excitation of the energy states in Gd3+ which are inactive for single-photon excitation and enables the observation of many new electric transitions which are invisible in the single-photon-induced luminescence. The competition between the two-photon-induced photon cascade emission and the single-photon-induced emission was manipulated to control the luminescence color of the glass. We demonstrated the change of the luminescence color from red to yellow and eventually to green by varying either the excitation wavelength or the excitation power density. PMID:26899189

  20. Ultrasonic unipolar pulse/echo instrument

    DOEpatents

    Hughes, Michael S.; Hsu, David K.; Thompson, Donald O.; Wormley, Samuel J.

    1993-01-01

    An ultrasonic unipolar pulse/echo instrument uses active switches and a timing and drive circuitry to control electrical energy to a transducer, the discharging of the transducer, and the opening of an electrical pathway to the receiving circuitry for the returning echoes. The active switches utilize MOSFET devices along with decoupling circuitry to insure the preservation of the unipolar nature of the pulses, insure fast transition times, and maintain broad band width and time resolution. A housing contains the various circuitry and switches and allows connection to a power supply and a movable ultrasonic transducer. The circuitry maintains low impedance input to the transducer during transmitting cycles, and high impedance between the transducer and the receiving circuit during receive cycles to maintain the unipolar pulse shape. A unipolar pulse is valuable for nondestructive evaluation, a prime use for the present instrument.

  1. Ultrasonic unipolar pulse/echo instrument

    DOEpatents

    Hughes, M.J.; Hsu, D.K.; Thompson, D.O.; Wormley, S.J.

    1993-04-06

    An ultrasonic unipolar pulse/echo instrument uses active switches and a timing and drive circuitry to control electrical energy to a transducer, the discharging of the transducer, and the opening of an electrical pathway to the receiving circuitry for the returning echoes. The active switches utilize MOSFET devices along with decoupling circuitry to insure the preservation of the unipolar nature of the pulses, insure fast transition times, and maintain broad band width and time resolution. A housing contains the various circuitry and switches and allows connection to a power supply and a movable ultrasonic transducer. The circuitry maintains low impedance input to the transducer during transmitting cycles, and high impedance between the transducer and the receiving circuit during receive cycles to maintain the unipolar pulse shape. A unipolar pulse is valuable for nondestructive evaluation, a prime use for the present instrument.

  2. Loschmidt Echo Revivals: Critical and Noncritical

    NASA Astrophysics Data System (ADS)

    Jafari, R.; Johannesson, Henrik

    2017-01-01

    A quantum phase transition is generally thought to imprint distinctive characteristics on the nonequilibrium dynamics of a closed quantum system. Specifically, the Loschmidt echo after a sudden quench to a quantum critical point—measuring the time dependence of the overlap between initial and time-evolved states—is expected to exhibit an accelerated relaxation followed by periodic revivals. We here introduce a new exactly solvable model, the extended Su-Schrieffer-Heeger model, the Loschmidt echo of which provides a counterexample. A parallell analysis of the quench dynamics of the three-site spin-interacting X Y model allows us to pinpoint the conditions under which a periodic Loschmidt revival actually appears.

  3. Light-echo spectroscopy of historic Supernovae

    NASA Astrophysics Data System (ADS)

    Krause, Oliver

    Young Galactic supernova remnants are unique laboratories for supernova physics. Due to their proximity they provide us with the most detailed view of the outcome of a supernova. However, the exact spectroscopic types of their original explosions have been undetermined so far -hindering to link the wealth of multi-wavelength knowledge about their remnants with the diverse population of supernovae. Light echoes, reflektions of the brilliant supernova burst of light by interstellar dust, provide a unique opportunity to reobserve today -with powerful scientific instruments of the 21st century -historic supernova exlosions even after hundreds of years and to conclude on their nature. We report on optical light-echo spectroscopy of two famous Galactic supernovae: Tycho Brahe's SN 1572 and the supernova that created the Cassiopeia A remnant around the year 1680. These observations finally recovered the missing spectroscopic classifications and provide new constraints on explosion models for future studies.

  4. Easy approach to assembling a biomimetic color film with tunable structural colors.

    PubMed

    Wang, Wentao; Tang, Bingtao; Ma, Wei; Zhang, Jian; Ju, Benzhi; Zhang, Shufen

    2015-06-01

    The self-assembly of silica microspheres into a close-packed array is a simple method of fabricating three-dimensional photonic crystal structural color films. However, the color is very dull because of the interferences of scattering and background light. In this study, we added a small quantity of surface-modified carbon black (CB) to the system of colloidal silica in n-propanol. The use of n-propanol as a dispersant is beneficial to the rapid development of photonic crystal films during the process of dip-coating. The doping of CB into silica microspheres can absorb background and scattering light, resulting in vivid structural colors.

  5. Echo Ranging/Probe Alert Performance Analysis.

    DTIC Science & Technology

    1982-11-04

    contract included technical analyses of acoustic communication equipment, system performance predictions, sea test design and data analysis, and...proposing functional system design alternatives. 2.0 SUMMARY OF WORK PERFORMED The JAYCOR effort focused on the analysis of the Echo Ranging/ Probe Alert...JAYCOR Document No. J640-020-82-2242, 16 August 1982, CONFIDENTIAL. 13. Probe Alert Design System Performance Estimates (U), J.L. Collins, JAYCOR Document

  6. Project Echo: Satellite-Tracking Radar

    NASA Technical Reports Server (NTRS)

    DeLange, O. E.

    1961-01-01

    The radar employed at the Bell Telephone Laboratories' Holmdel, New Jersey site for tracking the Echo I satellite was originally designed for the sole purpose of antenna pointing. Recently, however, it has also been employed to measure earth-balloon-earth path loss at regular intervals of time in order to ascertain the balloon's condition. The performance of the system and some of the data obtained are discussed.

  7. Facility Search Help | ECHO | US EPA

    EPA Pesticide Factsheets

    Search for compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  8. Eldor spin echoes and slow motions

    NASA Astrophysics Data System (ADS)

    Hornak, Joseph P.; Freed, Jack H.

    1983-10-01

    It is shown how an ELDOR technique based upon spin echoes and rapid stepping of the magnetic field may be employed to measure rotational correlation times, τ R for very slow motions. Experiments on PD-Tempone in 85% glycerol/ D 2O at low temperatures led to τ R values of 10 -4 to 10 -5 s obtained with a simple analysis of the data.

  9. State Compliance Monitoring Expectations | ECHO | US EPA

    EPA Pesticide Factsheets

    EPA sets national goals for how frequently facilities should be evaluated by the authorized enforcement agency for three programs included in ECHO (Clean Air Act, Clean Water Act, and Resource Conservation and Recovery Act). EPA develops Compliance Monitoring Strategies (CMSs) to ensure that the regulated facilities across the country are evaluated for compliance on a regular basis. Information on CMSs, evaluations (such as on-site inspections), and inspection frequency goals that are defined by each program is included.

  10. Light Echoes of Galactic Explosions and Eruptions

    NASA Astrophysics Data System (ADS)

    Rest, Armin; Bianco, Federica; Chornock, Ryan; Clocchiatti, Alejandro; Foley, Ryan; James, David; Matheson, Thomas; Narayan, Gautham; Olsen, Knut; Points, Sean; Prieto, Jose Luis; Smith, Chris; Smith, Nathan; Suntzeff, Nick; Welch, Doug; Zenteno, Alfredo

    2014-08-01

    We propose to search for light echoes (LEs) from the historical brightening of the Luminous Blue Variable (LBV) P Cygni using the KPNO 4m Mosaic 1.1 imager. We also propose to us DECam to continue our search for LEs from the the Crab supernova SN 1054. In addition, we continue to monitor the LEs from the Cas A and Tycho supernovae in order to identify suitable LE candidates for 3D-spectroscopy and spectral time series. In previously granted NOAO time, we have discovered light echoes of three ancient SNe in the LMC as well as from the historic SN events of Cas A and Tycho [2, 3], which allowed their spectroscopic classification [6, 7, 10] and 3D spectroscopy [8, 9]. Most recently, we discovered light echoes of the mid-19th-century Great Eruption of η Carinae using CTIO 4m Mosaic images [11]. Subsequent spectroscopic follow-up of Eta Carinae revealed that its outburst spectral type was most similar to those of G-type supergiants, rather than reported LBV outburst spectral types of F-type (or earlier) [11]. Our extension of LE techniques to LBV outbursts promises to extend our ability to record outburst activity hundreds of years into the past - a timescale which is likely a significant fraction of the brief final phases of these probable core- collapse supernova precursors.

  11. A multifilter approach to acoustic echo cancellation

    NASA Astrophysics Data System (ADS)

    Usher, John; Woszczyk, Wieslaw; Cooperstock, Jeremy

    2004-05-01

    Hands-free teleconferencing is increasingly frequent today. An important design consideration for any such communication tool that uses high-quality audio is the return echo caused by the acoustic coupling between the loudspeakers and microphones at each end of the conference. An echo-suppression filter (ESF) reduces the level of this return echo, increasing speech intelligibility. A new ESF has been designed based on a block frequency domain adaptive filter using the well-known least-mean-square (LMS) criteria. There are two important coefficients in LMS adaptive filters which affect how an ESF adapts to changing acoustic conditions at each end of the conference, such as double-talk conditions and moving electroacoustic transducers. Previous approaches to similar ESFs have used either a single or double pair of these coefficients, whereas the new model typically uses ten. The performance of single, double, and multifilter architectures was compared. Performance was evaluated using both empirical measurements and subjective listening tests. Speech and music were used as the stimuli for a two-way teleconferencing experiment. The new filter performed better than the single- and two-filter ESF designs, especially in conferencing conditions with frequent double talk, and the new ESF can be optimized to suit different acoustic situations.

  12. Light Echoes of Galactic Explosions and Eruptions

    NASA Astrophysics Data System (ADS)

    Rest, Armin; Bianco, Federica; Chornock, Ryan; Foley, Ryan; Kunder, Andrea; Matheson, Thomas; Olsen, Knut; Prieto, Jose Luis; Sinnott, Brendan; Smith, Chris; Smith, Nathan; Welch, Doug

    2013-08-01

    We propose to search for light echoes (LEs) from the historical brightening of the Luminous Blue Variable (LBV) P Cygni using the KPNO 4m Mosaic 1.1 imager. We also propose to conclude our search - so far unsuccessful - for LEs from the the Crab supernova SN 1054 by surveying one remaining region of the LE ellipsoid behind the plane of the supernova remnant on the sky. In addition, we continue to monitor the LEs from the Cas A and Tycho supernovae in order to identify suitable LE candidates for 3D-spectroscopy and spectral time series. In previously granted NOAO time, we have discovered light echoes of three ancient SNe in the LMC as well as from the historic SN events of Cas A and Tycho [2, 3], which allowed their spectroscopic classification [6, 7, 10] and 3D spectroscopy [8, 9]. Most recently, we discovered light echoes of the mid-19th-century Great Eruption of η Carinae using CTIO 4m Mosaic images [11]. Subsequent spectroscopic follow-up of Eta Carinae revealed that its outburst spectral type was most similar to those of G-type supergiants, rather than reported LBV outburst spectral types of F-type (or earlier) [11]. Our extension of LE techniques to LBV outbursts promises to extend our ability to record outburst activity hundreds of years into the past - a timescale which is likely a significant fraction of the brief final phases of these probable core- collapse supernova precursors.

  13. Color vision test

    MedlinePlus

    ... from birth) color vision problems: Achromatopsia -- complete color blindness , seeing only shades of gray Deuteranopia -- difficulty telling ... test - color; Ishihara color vision test Images Color blindness tests References Adams AJ, Verdon WA, Spivey BE. ...

  14. Photon absorptiometry

    SciTech Connect

    Velchik, M.G.

    1987-01-01

    Recently, there has been a renewed interest in the detection and treatment of osteoporosis. This paper is a review of the merits and limitations of the various noninvasive modalities currently available for the measurement of bone mineral density with special emphasis placed upon the nuclear medicine techniques of single-photon and dual-photon absorptiometry. The clinicians should come away with an understanding of the relative advantages and disadvantages of photon absorptiometry and its optimal clinical application. 49 references.

  15. Photonic Hypercrystals

    NASA Astrophysics Data System (ADS)

    Narimanov, Evgenii E.

    2014-10-01

    We introduce a new "universality class" of artificial optical media—photonic hypercrystals. These hyperbolic metamaterials, with periodic spatial variation of dielectric permittivity on subwavelength scale, combine the features of optical metamaterials and photonic crystals. In particular, surface waves supported by a hypercrystal possess the properties of both the optical Tamm states in photonic crystals and surface-plasmon polaritons at the metal-dielectric interface.

  16. The EChO science case

    NASA Astrophysics Data System (ADS)

    Tinetti, Giovanna; Drossart, Pierre; Eccleston, Paul; Hartogh, Paul; Isaak, Kate; Linder, Martin; Lovis, Christophe; Micela, Giusi; Ollivier, Marc; Puig, Ludovic; Ribas, Ignasi; Snellen, Ignas; Swinyard, Bruce; Allard, France; Barstow, Joanna; Cho, James; Coustenis, Athena; Cockell, Charles; Correia, Alexandre; Decin, Leen; de Kok, Remco; Deroo, Pieter; Encrenaz, Therese; Forget, Francois; Glasse, Alistair; Griffith, Caitlin; Guillot, Tristan; Koskinen, Tommi; Lammer, Helmut; Leconte, Jeremy; Maxted, Pierre; Mueller-Wodarg, Ingo; Nelson, Richard; North, Chris; Pallé, Enric; Pagano, Isabella; Piccioni, Guseppe; Pinfield, David; Selsis, Franck; Sozzetti, Alessandro; Stixrude, Lars; Tennyson, Jonathan; Turrini, Diego; Zapatero-Osorio, Mariarosa; Beaulieu, Jean-Philippe; Grodent, Denis; Guedel, Manuel; Luz, David; Nørgaard-Nielsen, Hans Ulrik; Ray, Tom; Rickman, Hans; Selig, Avri; Swain, Mark; Banaszkiewicz, Marek; Barlow, Mike; Bowles, Neil; Branduardi-Raymont, Graziella; du Foresto, Vincent Coudé; Gerard, Jean-Claude; Gizon, Laurent; Hornstrup, Allan; Jarchow, Christopher; Kerschbaum, Franz; Kovacs, Géza; Lagage, Pierre-Olivier; Lim, Tanya; Lopez-Morales, Mercedes; Malaguti, Giuseppe; Pace, Emanuele; Pascale, Enzo; Vandenbussche, Bart; Wright, Gillian; Ramos Zapata, Gonzalo; Adriani, Alberto; Azzollini, Ruymán; Balado, Ana; Bryson, Ian; Burston, Raymond; Colomé, Josep; Crook, Martin; Di Giorgio, Anna; Griffin, Matt; Hoogeveen, Ruud; Ottensamer, Roland; Irshad, Ranah; Middleton, Kevin; Morgante, Gianluca; Pinsard, Frederic; Rataj, Mirek; Reess, Jean-Michel; Savini, Giorgio; Schrader, Jan-Rutger; Stamper, Richard; Winter, Berend; Abe, L.; Abreu, M.; Achilleos, N.; Ade, P.; Adybekian, V.; Affer, L.; Agnor, C.; Agundez, M.; Alard, C.; Alcala, J.; Allende Prieto, C.; Alonso Floriano, F. J.; Altieri, F.; Alvarez Iglesias, C. A.; Amado, P.; Andersen, A.; Aylward, A.; Baffa, C.; Bakos, G.; Ballerini, P.; Banaszkiewicz, M.; Barber, R. J.; Barrado, D.; Barton, E. J.; Batista, V.; Bellucci, G.; Belmonte Avilés, J. A.; Berry, D.; Bézard, B.; Biondi, D.; Błęcka, M.; Boisse, I.; Bonfond, B.; Bordé, P.; Börner, P.; Bouy, H.; Brown, L.; Buchhave, L.; Budaj, J.; Bulgarelli, A.; Burleigh, M.; Cabral, A.; Capria, M. T.; Cassan, A.; Cavarroc, C.; Cecchi-Pestellini, C.; Cerulli, R.; Chadney, J.; Chamberlain, S.; Charnoz, S.; Christian Jessen, N.; Ciaravella, A.; Claret, A.; Claudi, R.; Coates, A.; Cole, R.; Collura, A.; Cordier, D.; Covino, E.; Danielski, C.; Damasso, M.; Deeg, H. J.; Delgado-Mena, E.; Del Vecchio, C.; Demangeon, O.; De Sio, A.; De Wit, J.; Dobrijévic, M.; Doel, P.; Dominic, C.; Dorfi, E.; Eales, S.; Eiroa, C.; Espinoza Contreras, M.; Esposito, M.; Eymet, V.; Fabrizio, N.; Fernández, M.; Femenía Castella, B.; Figueira, P.; Filacchione, G.; Fletcher, L.; Focardi, M.; Fossey, S.; Fouqué, P.; Frith, J.; Galand, M.; Gambicorti, L.; Gaulme, P.; García López, R. J.; Garcia-Piquer, A.; Gear, W.; Gerard, J.-C.; Gesa, L.; Giani, E.; Gianotti, F.; Gillon, M.; Giro, E.; Giuranna, M.; Gomez, H.; Gomez-Leal, I.; Gonzalez Hernandez, J.; González Merino, B.; Graczyk, R.; Grassi, D.; Guardia, J.; Guio, P.; Gustin, J.; Hargrave, P.; Haigh, J.; Hébrard, E.; Heiter, U.; Heredero, R. L.; Herrero, E.; Hersant, F.; Heyrovsky, D.; Hollis, M.; Hubert, B.; Hueso, R.; Israelian, G.; Iro, N.; Irwin, P.; Jacquemoud, S.; Jones, G.; Jones, H.; Justtanont, K.; Kehoe, T.; Kerschbaum, F.; Kerins, E.; Kervella, P.; Kipping, D.; Koskinen, T.; Krupp, N.; Lahav, O.; Laken, B.; Lanza, N.; Lellouch, E.; Leto, G.; Licandro Goldaracena, J.; Lithgow-Bertelloni, C.; Liu, S. J.; Lo Cicero, U.; Lodieu, N.; Lognonné, P.; Lopez-Puertas, M.; Lopez-Valverde, M. A.; Lundgaard Rasmussen, I.; Luntzer, A.; Machado, P.; MacTavish, C.; Maggio, A.; Maillard, J.-P.; Magnes, W.; Maldonado, J.; Mall, U.; Marquette, J.-B.; Mauskopf, P.; Massi, F.; Maurin, A.-S.; Medvedev, A.; Michaut, C.; Miles-Paez, P.; Montalto, M.; Montañés Rodríguez, P.; Monteiro, M.; Montes, D.; Morais, H.; Morales, J. C.; Morales-Calderón, M.; Morello, G.; Moro Martín, A.; Moses, J.; Moya Bedon, A.; Murgas Alcaino, F.; Oliva, E.; Orton, G.; Palla, F.; Pancrazzi, M.; Pantin, E.; Parmentier, V.; Parviainen, H.; Peña Ramírez, K. Y.; Peralta, J.; Perez-Hoyos, S.; Petrov, R.; Pezzuto, S.; Pietrzak, R.; Pilat-Lohinger, E.; Piskunov, N.; Prinja, R.; Prisinzano, L.; Polichtchouk, I.; Poretti, E.; Radioti, A.; Ramos, A. A.; Rank-Lüftinger, T.; Read, P.; Readorn, K.; Rebolo López, R.; Rebordão, J.; Rengel, M.; Rezac, L.; Rocchetto, M.; Rodler, F.; Sánchez Béjar, V. J.; Sanchez Lavega, A.; Sanromá, E.; Santos, N.; Sanz Forcada, J.; Scandariato, G.; Schmider, F.-X.; Scholz, A.; Scuderi, S.; Sethenadh, J.; Shore, S.; Showman, A.; Sicardy, B.; Sitek, P.; Smith, A.; Soret, L.; Sousa, S.; Stiepen, A.; Stolarski, M.; Strazzulla, G.; Tabernero, H. M.; Tanga, P.; Tecsa, M.; Temple, J.; Terenzi, L.; Tessenyi, M.; Testi, L.; Thompson, S.; Thrastarson, H.; Tingley, B. W.; Trifoglio, M.; Martín Torres, J.; Tozzi, A.; Turrini, D.; Varley, R.; Vakili, F.; de Val-Borro, M.; Valdivieso, M. L.; Venot, O.; Villaver, E.; Vinatier, S.; Viti, S.; Waldmann, I.; Waltham, D.; Ward-Thompson, D.; Waters, R.; Watkins, C.; Watson, D.; Wawer, P.; Wawrzaszk, A.; White, G.; Widemann, T.; Winek, W.; Wiśniowski, T.; Yelle, R.; Yung, Y.; Yurchenko, S. N.

    2015-12-01

    The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune—all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10-4 relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength

  17. Electrochemical fabrication and optical properties of porous tin oxide films with structural colors

    SciTech Connect

    Cheng, Hua; Shu, Shiwei; Lee, Chris; Zeng, Shanshan; Lu, Zhouguang; Lu, Jian E-mail: yangli@cityu.edu.hk; Li, Yang Yang E-mail: yangli@cityu.edu.hk

    2014-10-21

    Photonic crystals with porous features not only provide the capability to control light but also enable structural colors that are environmentally sensitive. Here, we report a novel kind of tin oxide-based photonic crystal featuring periodically arranged air pores fabricated by the periodic anodization of tin foil. The existence of a photonic band gap in the fabricated structure is verified by its vivid color, and its reflective spectra which are responsive to environmental stimuli. Furthermore, the sample colors (i.e., the photonic band gap positions) can be easily adjusted by manipulating the anodization parameters. The theoretical modeling results of these tin oxide photonic crystals agree well with the reported experimental ones.

  18. Topological photon

    NASA Astrophysics Data System (ADS)

    Tiwari, S. C.

    2008-03-01

    We associate intrinsic energy equal to hν /2 with the spin angular momentum of photon, and propose a topological model based on orbifold in space and tifold in time as topological obstructions. The model is substantiated using vector wavefield disclinations. The physical photon is suggested to be a particlelike topological photon and a propagating wave such that the energy hν of photon is equally divided between spin energy and translational energy, corresponding to linear momentum of hν /c. The enigma of wave-particle duality finds natural resolution, and the proposed model gives new insights into the phenomena of interference and emission of radiation.

  19. Color superconductivity

    SciTech Connect

    Wilczek, F.

    1997-09-22

    The asymptotic freedom of QCD suggests that at high density - where one forms a Fermi surface at very high momenta - weak coupling methods apply. These methods suggest that chiral symmetry is restored and that an instability toward color triplet condensation (color superconductivity) sets in. Here I attempt, using variational methods, to estimate these effects more precisely. Highlights include demonstration of a negative pressure in the uniform density chiral broken phase for any non-zero condensation, which we take as evidence for the philosophy of the MIT bag model; and demonstration that the color gap is substantial - several tens of MeV - even at modest densities. Since the superconductivity is in a pseudoscalar channel, parity is spontaneously broken.

  20. Structural colors: from plasmonic to carbon nanostructures.

    PubMed

    Xu, Ting; Shi, Haofei; Wu, Yi-Kuei; Kaplan, Alex F; Ok, Jong G; Guo, L Jay

    2011-11-18

    In addition to colorant-based pigmentation, structure is a major contributor to a material's color. In nature, structural color is often caused by the interaction of light with dielectric structures whose dimensions are on the order of visible-light wavelengths. Different optical interactions including multilayer interference, light scattering, the photonic crystal effect, and combinations thereof give rise to selective transmission or reflection of particular light wavelengths, which leads to the generation of structural color. Recent developments in nanofabrication of plasmonic and carbon nanostructures have opened another efficient way to control light properties at the subwavelength scale, including visible-light wavelength selection, which can produce structural color. In this Concept, the most relevant and representative achievements demonstrated over the last several years are presented and analyzed. These plasmonic and carbon nanostructures are believed to offer great potential for high-resolution color displays and spectral filtering applications.

  1. Echo tracker/range finder for radars and sonars

    NASA Technical Reports Server (NTRS)

    Constantinides, N. J. (Inventor)

    1982-01-01

    An echo tracker/range finder or altimeter is described. The pulse repetition frequency (PFR) of a predetermined plurality of transmitted pulses is adjusted so that echo pulses received from a reflecting object are positioned between transmitted pulses and divided their interpulse time interval into two time intervals having a predetermined ratio with respect to each other. The invention described provides a means whereby the arrival time of a plurality of echo pulses is defined as the time at which a composite echo pulse formed of a sum of the individual echo pulses has the highest amplitude. The invention is applicable to radar systems, sonar systems, or any other kind of system in which pulses are transmitted and echoes received therefrom.

  2. The photon

    NASA Astrophysics Data System (ADS)

    Collins, Russell L.

    2009-10-01

    There are no TEM waves, only photons. Lets build a photon, using a radio antenna. A short antenna (2L<< λ) simplifies the calculation, letting B fall off everywhere as 1/r^2. The Biot-Savart law finds B = (μ0/4π)(LI0/r^2)θφt. The magnetic flux thru a semi-circle of radius λ/2 is set equal to the flux quantum h/e, determining the needed source strength, LI0. From this, one can integrate the magnetic energy density over a sphere of radius λ/2 and finds it to be 1.0121 hc/λ. Pretty close. A B field collapses when the current ceases, but the photon evades this by creating a ɛ0E / t displacement current at center that fully supports the toroidal B assembly as it moves at c. This E=vxB arises because the photon moves at c. Stopped, a photon decays. At every point along the photon's path, an observer will note a transient oscillation of an E field. This sources the EM ``guiding wave'', carrying little or no energy and expanding at c. At the head of the photon, all these spherical guiding waves gather ``in-phase'' as a planar wavefront. This model speaks to all the many things we know about light. The photon is tiny, but its guiding wave is huge.

  3. Color transparency

    SciTech Connect

    Jennings, B.K.; Miller, G.A.

    1993-11-01

    The anomously large transmission of nucleons through a nucleus following a hard collision is explored. This effect, known as color transparency, is believed to be a prediction of QCD. The necessary conditions for its occurrence and the effects that must be included a realistic calculation are discussed.

  4. Color Sense

    ERIC Educational Resources Information Center

    Johnson, Heidi S. S.; Maki, Jennifer A.

    2009-01-01

    This article reports a study conducted by members of the WellU Academic Integration Subcommittee of The College of St. Scholastica's College's Healthy Campus Initiative plan whose purpose was to determine whether changing color in the classroom could have a measurable effect on students. One simple improvement a school can make in a classroom is…

  5. Project Echo: FM Demodulators with Negative Feedback

    NASA Technical Reports Server (NTRS)

    Ruthroff, Clyde L.

    1961-01-01

    The primary experimental objective of Project Echo was the transmission of radio communications between points on the earth by reflection from the balloon satellite. Owing to the large path losses from transmitter to receiver via the satellite, a wide-band frequency modulation technique was used in which bandwidth was traded for signal-to-noise ratio. This paper describes the FM receiving demodulators employed. Negative feedback applied to the local oscillator reduces the FM modulation index in the receiver IF amplifiers, resulting in threshold performance superior to that of conventional FM receivers.

  6. Decoherence and spin echo in biological systems.

    PubMed

    Nesterov, Alexander I; Berman, Gennady P

    2015-05-01

    The spin-echo approach is extended to include biocomplexes for which the interaction with dynamical noise, produced by the protein environment, is strong. Significant restoration of the free induction decay signal due to homogeneous (decoherence) and inhomogeneous (dephasing) broadening is demonstrated analytically and numerically for both an individual dimer of interacting chlorophylls and for an ensemble of dimers. Our approach does not require the use of small interaction constants between the electron states and the protein fluctuations. It is based on an exact and closed system of ordinary differential equations that can be easily solved for a wide range of parameters that are relevant for bioapplications.

  7. Extra echo spaces: ultrasonography and computerised tomography correlations.

    PubMed Central

    Wada, T; Honda, M; Matsuyama, S

    1982-01-01

    Among the echocardiograms of 844 patients of the International Goodwill Hospital from January 1980 to April 1981, 700 showed clinically inexplicable extra echo spaces. Fifty of the 700 had computerised tomography of their hearts which showed the extra echo spaces to be caused either by anterior or posterior subepicardial fat. Six of the 50 cases had both fat and pericardial effusions, which are difficult to differentiate echocardiographically unless follow-up clinical observations are performed. Subepicardial fat deposits are reasonable explanations for the extra echo spaces frequently observed by echocardiography: they correlate well with clinical findings. Subepicardial fat should be recognised as the cause of such extra echo spaces. Images PMID:7073903

  8. Temporal signal processing of dolphin biosonar echoes from salmon prey.

    PubMed

    Au, Whitlow W L; Ou, Hui Helen

    2014-08-01

    Killer whales project short broadband biosonar clicks. The broadband nature of the clicks provides good temporal resolution of echo highlights and allows for the discriminations of salmon prey. The echoes contain many highlights as the signals reflect off different surfaces and parts of the fish body and swim bladder. The temporal characteristics of echoes from salmon are highly aspect dependent and six temporal parameters were used in a support vector machine to discriminate between species. Results suggest that killer whales can classify salmon based on their echoes and provide some insight as to which features might enable the classification.

  9. Echoes of Historical Supernovae in the Milky Way Galaxy

    NASA Astrophysics Data System (ADS)

    Suntzeff, Nicholas B.; Rest, Armin; Welch, Douglas; Stubbs, Christopher; Smith, R. Chris; Olsen, Knut; Bergmann, Marcel; Clocchiatti, Alejandro; Minnite, Dante; Cook, Kem; Prieto, J. L.; Becker, Andy; Garg, Arti; Huber, Mark; Nikolaev, Sergei; Miknaitis, Gajus

    2006-08-01

    Our SuperMACHO collaboration has discovered echoes from four ancient supernovae in the Large Magellanic Cloud. The echoes were discovered using our SuperMACHO MOSAIC data difference images. The echo motions point to three supernova remnants which are listed as three of the six youngest SNRs in the LMC. These three remnants are also identified as Type Ia events, based on the X-ray spectral abundances. We have dated these echoes at 400-800 years. The echoes are easy to detect - they are as bright as 22 mag arcsec^-2, generally superluminal, a few arc- seconds wide, and tens of arc-seconds across. We are asking for NOAO time to get images of regions of significant dust concentration near the Galactic SNe Crab/1054, Tycho (4+3n KPNO 4m) and Kepler, Lupus/1006 (4n CTIO 4m). These supernovae are the youngest and/or brightest. By obtaining these images, we will be able to search for echoes in the second epoch images and have the first epoch images for a run next semester. Our group, which pioneered the discovery of echoes, will be at a great advantage for finding these echoes first if we can get these images this observing season. Finding echoes from historical supernovae and typeing them with spectra will be a major discovery for the NOAO 4m telescopes.

  10. Fast REDOR with CPMG multiple-echo acquisition

    NASA Astrophysics Data System (ADS)

    Hung, Ivan; Gan, Zhehong

    2014-01-01

    Rotational-Echo Double Resonance (REDOR) is a widely used experiment for distance measurements in solids. The conventional REDOR experiment measures the signal dephasing from hetero-nuclear recoupling under magic-angle spinning (MAS) in a point by point manner. A modified Carr-Purcell Meiboom-Gill (CPMG) multiple-echo scheme is introduced for fast REDOR measurement. REDOR curves are measured from the CPMG echo amplitude modulation under dipolar recoupling. The real time CPMG-REDOR experiment can speed up the measurement by an order of magnitude. The effects from hetero-nuclear recoupling, the Bloch-Siegert shift and echo truncation to the signal acquisition are discussed and demonstrated.

  11. Wetting in Color

    NASA Astrophysics Data System (ADS)

    Burgess, Ian Bruce

    Colorimetric litmus tests such as pH paper have enjoyed wide commercial success due to their inexpensive production and exceptional ease of use. However, expansion of colorimetry to new sensing paradigms is challenging because macroscopic color changes are seldom coupled to arbitrary differences in the physical/chemical properties of a system. In this thesis I present in detail the development of Wetting in Color Technology, focusing primarily on its application as an inexpensive and highly selective colorimetric indicator for organic liquids. The technology exploits chemically-encoded inverse-opal photonic crystals to control the infiltration of fluids to liquid-specific spatial patterns, projecting minute differences in liquids' wettability to macroscopically distinct, easy-to-visualize structural color patterns. It is shown experimentally and corroborated with theoretical modeling using percolation theory that the high selectivity of wetting, upon-which the sensitivity of the indicator relies, is caused by the highly symmetric structure of our large-area, defect-free SiO2 inverse-opals. The regular structure also produces a bright iridescent color, which disappears when infiltrated with liquid - naturally coupling the optical and fluidic responses. Surface modification protocols are developed, requiring only silanization and selective oxidation, to facilitate the deterministic design of an indicator that differentiates a broad range of liquids. The resulting tunable, built-in horizontal and vertical chemistry gradients allow the wettability threshold to be tailored to specific liquids across a continuous range, and make the readout rely only on countable color differences. As wetting is a generic fluidic phenomenon, Wetting in Color technology could be suitable for applications in authentication or identification of unknown liquids across a broad range of industries. However, the generic nature of the response also ensures chemical non-specificity. It is shown

  12. Impact echo scanning of concrete and wood

    NASA Astrophysics Data System (ADS)

    Sack, Dennis A.; Olson, Larry D.; Aouad, Marwan F.

    1995-05-01

    This paper presents an overview of a new nondestructive testing (NDT) system that allows rapid nondestructive assessment of many types of structural materials. The new system is based on scanning impact echo (IE), using a rolling receiver, digitally controlled impact source, and a distance measurement wheel integrated into a system that is capable of performing over 3000 IE tests per hour. The system has been successfully used on both concrete and wood for condition assessment. Previously, impact echo testing has been limited to point-by-point testing at rates of typically 30 - 60 points per hour. The new system is usable on any flat, relatively smooth surface such as floor slabs, pavements, walls, columns, beams, etc. In addition to IE scanning, the new system has recently been expanded to allow the performance of spectral analysis of surface waves (SASW) scanning on concrete and wood. The SASW method allows the measurement of material stiffness (modulus) versus depth, and therefore can give a profile of the material condition versus depth. Included in this paper are brief discussions of the IE and SASW methods, the scanner system hardware, and the software which was developed to enable efficient processing, analysis, and display of the test data and results. Also included are sample data plots and a case history presentation of the use of the system in the field, including one in which 23,000 IE tests were performed on an elevated floor slab in approximately 16 hours of testing time.

  13. Light Echoes of Transients and Variables

    NASA Astrophysics Data System (ADS)

    Rest, Armin

    2012-04-01

    abstract-type="normal">SummaryTycho Brahe's observations of a supernova in 1572 challenged the contemporaneous European view of the cosmos that the celestial realm was unchanging. 439 years later we have once again seen the light that Tycho saw, as some of the light from the 1572 supernova is reflected off dust and is only now reaching Earth. These light echoes, as well as ones detected from other transients and variables, give us a very rare opportunity in astronomy: direct observation of the cause (the supernova explosion) and the effect (the supernova remnant) of the same astronomical event. Furthermore, in some cases we can compare light echoes at different angles around a supernova remnant, and thus investigate possible asymmetry in the supernova explosion. In addition, in cases where the scattering dust is favorably positioned, the geometric distance to the SN remnant can be determined using polarization measurements. These techniques have been successfully applied to various transients in the last decade, and the talk gave an overview of the scientific results and techniques, with a particular focus on the challenges we will face in the current and upcoming wide-field time-domain surveys.

  14. Neutron spin echo scattering angle measurement (SESAME)

    SciTech Connect

    Pynn, R.; Fitzsimmons, M.R.; Fritzsche, H.; Gierlings, M.; Major, J.; Jason, A.

    2005-05-15

    We describe experiments in which the neutron spin echo technique is used to measure neutron scattering angles. We have implemented the technique, dubbed spin echo scattering angle measurement (SESAME), using thin films of Permalloy electrodeposited on silicon wafers as sources of the magnetic fields within which neutron spins precess. With 30-{mu}m-thick films we resolve neutron scattering angles to about 0.02 deg. with neutrons of 4.66 A wavelength. This allows us to probe correlation lengths up to 200 nm in an application to small angle neutron scattering. We also demonstrate that SESAME can be used to separate specular and diffuse neutron reflection from surfaces at grazing incidence. In both of these cases, SESAME can make measurements at higher neutron intensity than is available with conventional methods because the angular resolution achieved is independent of the divergence of the neutron beam. Finally, we discuss the conditions under which SESAME might be used to probe in-plane structure in thin films and show that the method has advantages for incident neutron angles close to the critical angle because multiple scattering is automatically accounted for.

  15. Nanoparticle-tuned structural color from polymer opals.

    PubMed

    Pursiainen, Otto L; Baumberg, Jeremy J; Winkler, Holger; Viel, Benjamin; Spahn, Peter; Ruhl, Tilmann

    2007-07-23

    The production of high-quality low-defect single-domain flexible polymer opals which possess fundamental photonic bandgaps tuneable across the visible and near-infrared regions is demonstrated in an industrially-scalable process. Incorporating sub-50nm nanoparticles into the interstices of the fcc lattice dramatically changes the perceived color without affecting the lattice quality. Contrary to iridescence based on Bragg diffraction, color generation arises through spectrally-resonant scattering inside the 3D photonic crystal. Viewing angles widen beyond 40 masculine removing the strong dependence of the perceived color on the position of light sources, greatly enhancing the color appearance. This opens up a range of decorative, sensing, security and photonic applications, and suggests an origin for structural colors in Nature.

  16. The Long wave (11-16 μm) spectrograph for the EChO M3 Mission Candidate study

    NASA Astrophysics Data System (ADS)

    Bowles, N. E.; Tecza, M.; Barstow, J. K.; Temple, J. M.; Irwin, P. G. J.; Fletcher, L. N.; Calcutt, S.; Hurley, J.; Ferlet, M.; Freeman, D.

    2015-12-01

    The results for the design study of the Long Wave Infrared Module (LWIR), a goal spectroscopic channel for the EChO ESA medium class candidate mission, are presented. The requirements for the LWIR module were to provide coverage of the 11-16 μm spectral range at a moderate resolving power of at least R = 30, whilst minimising noise contributions above photon due to the thermal background of the EChO instrument and telescope, and astrophysical sources such as the zodiacal light. The study output module design is a KRS-6 prism spectrograph with aluminium mirror beam expander and coated germanium lenses for the final focusing elements. Thermal background considerations led to enclosing the beam in a baffle cooled to approximately 25-29 K. To minimise diffuse astrophysical background contributions due to the zodiacal light, anamorphic designs were considered in addition to the elliptical input beam provided by the EChO telescope. Given the requirement that measurements in this waveband place on the performance of the infrared detector array, an additional study on the likely scientific return with lower resolving power ( R < 30) is included. If specific high priority molecules on moderately warm giant planets (e.g. CO2, H2O) are targeted, the LWIR channel can still provide improvements in determining the atmospheric temperature structure and molecular abundances. Thus, the inclusion of even a coarse-resolution (R≈10) LWIR module would still make an important contribution to measurements of exoplanet atmospheres made by EChO.

  17. The Future of ECHO: Evaluating Open Source Possibilities

    NASA Astrophysics Data System (ADS)

    Pilone, D.; Gilman, J.; Baynes, K.; Mitchell, A. E.

    2012-12-01

    NASA's Earth Observing System ClearingHOuse (ECHO) is a format agnostic metadata repository supporting over 3000 collections and 100M science granules. ECHO exposes FTP and RESTful Data Ingest APIs in addition to both SOAP and RESTful search and order capabilities. Built on top of ECHO is a human facing search and order web application named Reverb. ECHO processes hundreds of orders, tens of thousands of searches, and 1-2M ingest actions each week. As ECHO's holdings, metadata format support, and visibility have increased, the ECHO team has received requests by non-NASA entities for copies of ECHO that can be run locally against their data holdings. ESDIS and the ECHO Team have begun investigations into various deployment and Open Sourcing models that can balance the real constraints faced by the ECHO project with the benefits of providing ECHO capabilities to a broader set of users and providers. This talk will discuss several release and Open Source models being investigated by the ECHO team along with the impacts those models are expected to have on the project. We discuss: - Addressing complex deployment or setup issues for potential users - Models of vetting code contributions - Balancing external (public) user requests versus our primary partners - Preparing project code for public release, including navigating licensing issues related to leveraged libraries - Dealing with non-free project dependencies such as commercial databases - Dealing with sensitive aspects of project code such as database passwords, authentication approaches, security through obscurity, etc. - Ongoing support for the released code including increased testing demands, bug fixes, security fixes, and new features.

  18. Colorful drying.

    PubMed

    Lakio, Satu; Heinämäki, Jyrki; Yliruusi, Jouko

    2010-03-01

    Drying is one of the standard unit operations in the pharmaceutical industry and it is important to become aware of the circumstances that dominate during the process. The purpose of this study was to test microcapsulated thermochromic pigments as heat indicators in a fluid bed drying process. The indicator powders were manually granulated with alpha-lactose monohydrate resulting in three particle-size groups. Also, pellets were coated with the indicator powders. The granules and pellets were fluidized in fluid bed dryer to observe the progress of the heat flow in the material and to study the heat indicator properties of the indicator materials. A tristimulus colorimeter was used to measure CIELAB color values. Color indicator for heat detection can be utilized to test if the heat-sensitive API would go through physical changes during the pharmaceutical drying process. Both the prepared granules and pellets can be used as heat indicator in fluid bed drying process. The colored heat indicators give an opportunity to learn new aspects of the process at real time and could be exploded, for example, for scaling-up studies.

  19. Introduction To Color Vision

    NASA Astrophysics Data System (ADS)

    Thorell, Lisa G.

    1983-08-01

    Several human cognitive studies have reported that color facilitates certain learning, memory and search tasks. Consideration of the color-opponent organization of human color vision and the spatial modulation transfer function for color suggests several simple sensory explanations.

  20. Photon generator

    DOEpatents

    Srinivasan-Rao, Triveni

    2002-01-01

    A photon generator includes an electron gun for emitting an electron beam, a laser for emitting a laser beam, and an interaction ring wherein the laser beam repetitively collides with the electron beam for emitting a high energy photon beam therefrom in the exemplary form of x-rays. The interaction ring is a closed loop, sized and configured for circulating the electron beam with a period substantially equal to the period of the laser beam pulses for effecting repetitive collisions.

  1. Neural coding of echo-envelope disparities in echolocating bats.

    PubMed

    Borina, Frank; Firzlaff, Uwe; Wiegrebe, Lutz

    2011-05-01

    The effective use of echolocation requires not only measuring the delay between the emitted call and returning echo to estimate the distance of an ensonified object. To locate an object in azimuth and elevation, the bat's auditory system must analyze the returning echoes in terms of their binaural properties, i.e., the echoes' interaural intensity and time differences (IIDs and ITDs). The effectiveness of IIDs for echolocation is undisputed, but when bats ensonify complex objects, the temporal structure of echoes may facilitate the analysis of the echo envelope in terms of envelope ITDs. Using extracellular recordings from the auditory midbrain of the bat, Phyllostomus discolor, we found a population of neurons that are sensitive to envelope ITDs of echoes of their sonar calls. Moreover, the envelope-ITD sensitivity improved with increasing temporal fluctuations in the echo envelopes, a sonar parameter related to the spatial statistics of complex natural reflectors like vegetation. The data show that in bats envelope ITDs may be used not only to locate external, prey-generated rustling sounds but also in the context of echolocation. Specifically, the temporal fluctuations in the echo envelope, which are created when the sonar emission is reflected from a complex natural target, support ITD-mediated echolocation.

  2. 21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ultrasonic pulsed echo imaging system. 892.1560 Section 892.1560 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1560 Ultrasonic pulsed echo...

  3. 21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ultrasonic pulsed echo imaging system. 892.1560 Section 892.1560 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1560 Ultrasonic pulsed echo...

  4. 21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultrasonic pulsed echo imaging system. 892.1560 Section 892.1560 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1560 Ultrasonic pulsed echo...

  5. ECHOS: Early Childhood Hands-On Science Efficacy Study

    ERIC Educational Resources Information Center

    Brown, Judy A.; Greenfield, Daryl B.; Bell, Elizabeth; Juárez, Cheryl Lani; Myers, Ted; Nayfeld, Irena

    2013-01-01

    "ECHOS: Early Childhood Hands-On Science" was developed at the Miami Science Museum as a comprehensive set of science lessons sequenced to lead children toward a deeper understanding of science content and the use of science process skills. The purpose of the research is to determine whether use of the "ECHOS" model will…

  6. Psychoacoustic influences of the echoing environments of prehistoric art

    NASA Astrophysics Data System (ADS)

    Waller, Steven J.

    2002-11-01

    Cave paintings and ancient petroglyphs around the world are typically found in echo rich locations such as caves, canyons, and rocky cliff faces. Analysis of field data shows that echo decibel levels at a large number of prehistoric art sites are higher than those at nondecorated locations. The selection of these echoing environments by the artists appears not to be a mere coincidence. This paper considers the perception of an echoed sound as a psychoacoustic event that would have been inexplicable to ancient humans. A variety of ancient legends from cultures on several continents attribute the phenomenon of echoes to supernatural beings. These legends, together with the quantitative data, strongly implicate echoing as relevant to the artists of the past. The notion that the echoes were caused by spirits within the rock would explain not only the unusual locations of prehistoric art, but also the perplexing subject matter. For example, the common theme of hoofed animal imagery could have been inspired by echoes of percussion noises perceived as hoof beats. Further systematic acoustical studies of prehistoric art sites is warranted. Conservation of the natural acoustic properties of rock art environments--a previously unrecognized need--is urged.

  7. 21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ultrasonic pulsed echo imaging system. 892.1560 Section 892.1560 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... system. (a) Identification. An ultrasonic pulsed echo imaging system is a device intended to project...

  8. 21 CFR 892.1560 - Ultrasonic pulsed echo imaging system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ultrasonic pulsed echo imaging system. 892.1560 Section 892.1560 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... system. (a) Identification. An ultrasonic pulsed echo imaging system is a device intended to project...

  9. Photonic lanterns

    NASA Astrophysics Data System (ADS)

    Leon-Saval, Sergio G.; Argyros, Alexander; Bland-Hawthorn, Joss

    2013-12-01

    Multimode optical fibers have been primarily (and almost solely) used as "light pipes" in short distance telecommunications and in remote and astronomical spectroscopy. The modal properties of the multimode waveguides are rarely exploited and mostly discussed in the context of guiding light. Until recently, most photonic applications in the applied sciences have arisen from developments in telecommunications. However, the photonic lantern is one of several devices that arose to solve problems in astrophotonics and space photonics. Interestingly, these devices are now being explored for use in telecommunications and are likely to find commercial use in the next few years, particularly in the development of compact spectrographs. Photonic lanterns allow for a low-loss transformation of a multimode waveguide into a discrete number of single-mode waveguides and vice versa, thus enabling the use of single-mode photonic technologies in multimode systems. In this review, we will discuss the theory and function of the photonic lantern, along with several different variants of the technology. We will also discuss some of its applications in more detail. Furthermore, we foreshadow future applications of this technology to the field of nanophotonics.

  10. Photon diffraction

    NASA Astrophysics Data System (ADS)

    Hodge, John

    2009-11-01

    In current light models, a particle-like model of light is inconsistent with diffraction observations. A model of light is proposed wherein photon inferences are combined with the cosmological scalar potential model (SPM). That the photon is a surface with zero surface area in the travel direction is inferred from the Michelson-Morley experiment. That the photons in slits are mathematically treated as a linear antenna array (LAA) is inferred from the comparison of the transmission grating interference pattern and the single slit diffraction pattern. That photons induce a LAA wave into the plenum is inferred from the fractal model. Similarly, the component of the photon (the hod) is treated as a single antenna radiating a potential wave into the plenum. That photons are guided by action on the surface of the hod is inferred from the SPM. The plenum potential waves are a real field (not complex) that forms valleys, consistent with the pilot waves of the Bohm interpretation of quantum mechanics. Therefore, the Afshar experiment result is explained, supports Bohm, and falsifies Copenhagen. The papers may be viewed at http://web.citcom.net/˜scjh/.

  11. Echoes from Ancient supernovae in the Large Magellanic Cloud

    SciTech Connect

    Rest, A; Suntzeff, N B; Olsen, K; Prieto, J L; Smith, R C; Welch, D L; Becker, A; Bergmann, M; Clocchiatti, A; Cook, K; Garg, A; Huber, M; Miknaitis, G; Minniti, D; Nikolaev, S; Stubbs, C

    2005-06-15

    In principle, historical supernovae could still be visible as scattered-light echoes even centuries later [1, 2]. Searches for surface brightness variations using photographic plates have not recovered any echoes in the regions of historical Galactic supernovae [3]. Using differenced images, our SuperMACHO collaboration has discovered three faint new variable surface brightness complexes with high apparent proper motion pointing back to well-defined positions in the Large Magellanic Cloud (LMC). These correspond to three of the six smallest (and likely youngest) supernova remnants believed to be due to thermonuclear (Type Ia) supernovae [4]. A lower limit to the age of these remnants and echoes is 200 years given the lack of any reported LMC supernovae until 1987. The discovery of historical supernova echoes in the LMC suggests that similar echoes for Galactic supernovae such as Tycho, Kepler, Cas A, or SN1006 could be visible using standard image differencing techniques.

  12. Diurnal variation of overdense meteor echo duration and ozone

    NASA Technical Reports Server (NTRS)

    Simek, Milos

    1992-01-01

    The diurnal variation of the median duration of overdense sporadic radar meteor echoes is examined. The meteors recorded in August, December, and January by the Ondrejov meteor radar during the period 1958-1990 were used for the analysis. A maximum median echo duration 1-3 hours after the time of local sunrise in the meteor region confirms the already known sunrise effect. Minimum echo duration occurring at the time of sunset seems to be the most important point of diurnal variation of the echo duration, when ozone is no longer dissociated by solar UV radiation. The effect of diurnal changes of the echo duration should be considered when the mass distribution of meteor showers is analyzed.

  13. Enhanced sensitivity to echo cues in blind subjects.

    PubMed

    Dufour, André; Després, Olivier; Candas, Victor

    2005-09-01

    Many studies have reported that blind people compensate for their visual deficit by sharpening auditory processes. Here we compare the sensitivity to echo cues between blind and sighted subjects. In the first experiment, the blind subjects were more accurate than the sighted subjects in localizing an object on the basis of echo cues. To ensure that enhanced echolocalization abilities were not only due to the fact that blind individuals are more used to consciously paying attention to echo cues and are more familiar with this kind of tasks than sighted subjects, we tested both groups of subjects in a simple azimuthal localization task of auditory stimuli. In this second experiment, we evaluated the influence of irrelevant echo signals on auditory localization by placing the subjects and the sound sources at different positions in a sound reverberant room. Results revealed that blind subjects exhibit a higher sensitivity to echo signals than sighted subjects.

  14. Light echoes from ancient supernovae in the Large Magellanic Cloud.

    PubMed

    Rest, Armin; Suntzeff, Nicholas B; Olsen, Knut; Prieto, Jose Luis; Smith, R Chris; Welch, Douglas L; Becker, Andrew; Bergmann, Marcel; Clocchiatti, Alejandro; Cook, Kem; Garg, Arti; Huber, Mark; Miknaitis, Gajus; Minniti, Dante; Nikolaev, Sergei; Stubbs, Christopher

    2005-12-22

    The light from historical supernovae could in principle still be visible as scattered-light echoes centuries after the explosion. The detection of light echoes could allow us to pinpoint the supernova event both in position and age and, most importantly, permit the acquisition of spectra to determine the 'type' of the supernova centuries after the direct light from the explosion first reached Earth. Although echoes have been discovered around some nearby extragalactic supernovae, targeted searches have not found any echoes in the regions of historical Galactic supernovae. Here we report three faint variable-surface-brightness complexes with high apparent proper motions pointing back to three of the six smallest (and probably youngest) previously catalogued supernova remnants in the Large Magellanic Cloud, which are believed to have been thermonuclear (type Ia) supernovae. Using the distance and apparent proper motions of these echo arcs, we estimate ages of 610 and 410 years for two of them.

  15. Echo power analysis and simulation of low altitude radio fuze

    NASA Astrophysics Data System (ADS)

    Chen, Xiaolu; Chen, Biao; Xu, Tao; Xu, Suqin

    2013-01-01

    The echo power from the earth gound which was received by fuze plays an important role in aerial defense missile, especially when the fuze is working in the look down mode. It is necessary to analyze and even simulate the echo power signals to enhance the missile's anti-jamming ability. In this paper, the quantity of echo power from the earth ground of low altitude radio fuze was analyzed in detail. Three boundary equations of area irradiated by electromagnetic beams were presented, which include two equidistant curve equations and one equal-Doppler curve equation. The relationship between the working mode and the critical height was analyzed. The calculating formula of echo power waveform was derived. And based on the derived formula, the correlation between the maximal echo power and the incident height was given and simulated, which would be helpful for the further researches of low altitude radio fuze.

  16. Structural color mechanism in the Papilio blumei butterfly.

    PubMed

    Lo, Mei-Ling; Lee, Cheng-Chung

    2014-02-01

    The structural color found in biological systems has complicated nanostructure. It is very important to determine its color mechanism. In this study, the 2D photonic crystal structures of the Papilio blumei butterfly were constructed, and the corresponding reflectance spectra were simulated by the finite-difference time-domain method. The structural color of the butterfly depends on the incident angle of light, film thickness, film material (film refractive index), and the size of the air hole (effective refractive index). Analysis of simulations can help us understand the hue, brightness, and saturation of structural color on the butterfly wing. As a result, the analysis can help us fabricate expected structural color.

  17. Acoustooptic pulse-echo transducer system

    NASA Technical Reports Server (NTRS)

    Claus, R. O.; Wade, J. C.

    1983-01-01

    A pulse-echo transducer system which uses an ultrasonic generating element and an optical detection technique is described. The transmitting transducer consists of a concentric ring electrode pattern deposited on a circular, X-cut quartz substrate with a circular hole in the center. The rings are independently pulsed with a sequence high voltage signals phased in such a way that the ultrasonic waves generated by the separate rings superimpose to produce a composite field which is focused at a controllable distance below the surface of the specimen. The amplitude of the field reflected from this focus position is determined by the local reflection coefficient of the medium at the effective focal point. By processing the signals received for a range of ultrasonic transducer array focal lengths, the system can be used to locate and size anomalies within solids and liquids. Applications in both nondestructive evaluation and biomedical scanning are suggested.

  18. Echo Mapping of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Horne, K.

    Echo mapping exploits light travel time delays, revealed by multi-wavelength variability studies, to map the geometry, kinematics, and physical conditions of reprocessing sites in photo-ionized gas flows. In active galactic nuclei (AGN), the ultraviolet to near infrared light arises in part from reprocessing of EUV and X-ray light from a compact and erratically variable source in the nucleus. The observed time delays, 0.1-2 days for the continuum and 1-100 days for the broad emission lines, probe regions only micro-arcseconds from the nucleus. Emission-line delays reveal radially stratified ionization zones, identify the nature of the gas motions, and estimate the masses of the central black holes. Continuum time delays map the temperature-radius structure of AGN accretion discs, and provide distances that may be accurate enough to realize the potential of AGNs as cosmological probes.

  19. Dual-rail optical gradient echo memory

    NASA Astrophysics Data System (ADS)

    Higginbottom, D. B.; Geng, J.; Campbell, G. T.; Hosseini, M.; Cao, M. T.; Sparkes, B. M.; Bernu, J.; Robins, N. P.; Lam, P. K.; Buchler, B. C.

    2015-09-01

    We introduce a scheme for the parallel storage of frequency separated signals in an optical memory and demonstrate that this dual-rail storage is a suitable memory for high fidelity frequency qubits. The two signals are stored simultaneously in the Zeeman-split Raman absorption lines of a cold atom ensemble using gradient echo memory techniques. Analysis of the split-Zeeman storage shows that the memory can be configured to preserve the relative amplitude and phase of the frequency separated signals. In an experimental demonstration dual-frequency pulses are recalled with 35% efficiency, 82% interference fringe visibility, and 6 degrees phase stability. The fidelity of the frequency-qubit memory is limited by frequency-dependent polarisation rotation and ambient magnetic field fluctuations, our analysis describes how these can be addressed in an alternative configuration.

  20. Spin Echo and Interference in Synchrotrons

    SciTech Connect

    Chao, Alex; /SLAC

    2006-11-30

    Spin dynamics in crossing a single depolarization resonance is a well-studied subject. One well-known example is that of Froissart and Stora in 1960. More is needed to complete the understanding, particularly of the transient effects, when crossing a single resonance, but question arises what happens if we cross two resonances or cross a single resonance twice. When a resonance is crossed twice, the particle's spin dynamics encounters two additional phenomena. First, the two crossings will interfere with each other, leading to an interference effect. Second, there will be a spin echo effect. We discuss these two effects in this report. Two proposals to test these effects experimentally are made at the end.

  1. Simultaneous Acquisition of Gradient Echo / Spin Echo BOLD and Perfusion with a Separate Labeling Coil

    PubMed Central

    Glielmi, C.B.; Xu, Q.; Craddock, R.C.; Hu, X.

    2010-01-01

    Arterial spin labeling (ASL) based cerebral blood flow (CBF) imaging complements blood oxygenation level dependent (BOLD) imaging with a measure that is more quantitative and has better specificity to neuronal activation. Relative to gradient echo (GE) BOLD, spin echo (SE) BOLD has better spatial specificity because it is less biased to large draining veins. While there have been many studies comparing simultaneously acquired CBF data with GE BOLD data in fMRI, there have been few studies comparing CBF with SE BOLD and no study comparing all three. We present a pulse sequence that simultaneously acquires CBF data with a separate labeling coil, GE BOLD and SE BOLD images. Simultaneous acquisition avoids inter-scan variability, allowing more direct assessment and comparison of each contrast’s relative specificity and reproducibility. Furthermore, it facilitates studies that may benefit from multiple complementary measures. PMID:20648682

  2. Dynamic hysteresis between gradient echo and spin echo attenuations in dynamic susceptibility contrast imaging.

    PubMed

    Xu, Chao; Kiselev, Valerij G; Möller, Harald E; Fiebach, Jochen B

    2013-04-01

    Perfusion measurements using dynamic susceptibility contrast imaging provide additional information about the mean vessel size of microvasculature when supplemented with a dual gradient echo (GE) - spin echo (SE) contrast. Dynamic increase in the corresponding transverse relaxation rate constant changes, ΔR2GE and ΔR2SE , forms a loop on the (Δ R2SE3/2, ΔR2GE ) plane, rather than a reversible line. The shape of the loop and the direction of its passage differentiate between healthy brain and pathological tissue, such as tumour and ischemic tissue. By considering a tree model of microvasculature, the direction of the loop is found to be influenced mainly by the relative arterial and venous blood volume, as well as the tracer bolus dispersion. A parameter Λ is proposed to characterize the direction and shape of the loop, which might be considered as a novel imaging marker for describing the pathology of cerebrovascular network.

  3. Colloidal assembly in Leidenfrost drops for noniridescent structural color pigments.

    PubMed

    Lim, Che Ho; Kang, Hyelim; Kim, Shin-Hyun

    2014-07-22

    Noniridescent structural color pigments have great potential as alternatives to conventional chemical color pigments in many coloration applications due to their nonbleaching and color-tunable properties. In this work, we report a novel method to create photonic microgranules composed of glassy packing of silica particles and small fraction of carbon black nanoparticles, which show pronounced structural colors with low angle-dependency. To prepare isotropic random packing in each microgranule, a Leidenfrost drop, which is a drop levitated by its own vapor on a hot surface, is employed as a template for fast consolidation of silica particles. The drop randomly migrates over the hot surface and rapidly shrinks, while maintaining its spherical shape, thereby consolidating silica particles to granular structures. Carbon black nanoparticles incorporated in the microgranules suppress incoherent multiple scattering, thereby providing improved color contrast. Therefore, photonic microgranules in a full visible range can be prepared by adjusting the size of silica particles with insignificant whitening.

  4. Recent Results for the ECHo Experiment

    NASA Astrophysics Data System (ADS)

    Hassel, C.; Blaum, K.; Goodacre, T. Day; Dorrer, H.; Düllmann, Ch. E.; Eberhardt, K.; Eliseev, S.; Enss, C.; Filianin, P.; Fäßler, A.; Fleischmann, A.; Gastaldo, L.; Goncharov, M.; Hengstler, D.; Jochum, J.; Johnston, K.; Keller, M.; Kempf, S.; Kieck, T.; Köster, U.; Krantz, M.; Marsh, B.; Mokry, C.; Novikov, Yu. N.; Ranitzsch, P. C. O.; Rothe, S.; Rischka, A.; Runke, J.; Saenz, A.; Schneider, F.; Scholl, S.; Schüssler, R. X.; Simkovic, F.; Stora, T.; Thörle-Pospiech, P.; Türler, A.; Veinhard, M.; Wegner, M.; Wendt, K.; Zuber, K.

    2016-08-01

    The Electron Capture in ^{163}Ho experiment, ECHo, is designed to investigate the electron neutrino mass in the sub-eV range by means of the analysis of the calorimetrically measured spectrum following the electron capture (EC) in ^{163}Ho. Arrays of low-temperature metallic magnetic calorimeters (MMCs), read-out by microwave SQUID multiplexing, will be used in this experiment. With a first MMC prototype having the ^{163}Ho source ion-implanted into the absorber, we performed the first high energy resolution measurement of the EC spectrum, which demonstrated the feasibility of such an experiment. In addition to the technological challenges for the development of MMC arrays, which preserve the single pixel performance in terms of energy resolution and bandwidth, the success of the experiment relies on the availability of large ultra-pure ^{163}Ho samples, on the precise description of the expected spectrum, and on the identification and reduction of background. We present preliminary results obtained with standard MMCs developed for soft X-ray spectroscopy, maXs-20, where the ^{163}Ho ion-implantation was performed using a high-purity ^{163}Ho source produced by advanced chemical and mass separation. With these measurements, we aim at determining an upper limit for the background level due to source contamination and provide a refined description of the calorimetrically measured spectrum. We discuss the plan for a medium scale experiment, ECHo-1k, in which about 1000 mathrm {Bq} of high-purity ^{163}Ho will be ion-implanted into detector arrays. With one year of measuring time, we will be able to achieve a sensitivity on the electron neutrino mass below 20 eV/c^2 (90 % C.L.), improving the present limit by more than one order of magnitude. This experiment will guide the necessary developments to reach the sub-eV sensitivity.

  5. Natural photonic crystals: formation, structure, function

    NASA Astrophysics Data System (ADS)

    Bartl, Michael H.; Dahlby, Michael R.; Barrows, Frank P.; Richens, Zachary J.; Terooatea, Tommy; Jorgensen, Matthew R.

    2012-03-01

    The structure and properties of natural photonic crystals are discussed using the colored scales of the beetle Lamprocyphus augustus as an example. While the exact mechanism behind the formation of these biopolymeric photonic structures has yet to be fully explored, similarities of these structures to intracellular cubic membrane architectures are introduced. Some crucial parameters behind the formation of cubic membranes are discussed. Using these insights, intracellular cubic membrane structures are transformed into an extracellular environment.

  6. Do focal colors look particularly "colorful"?

    PubMed

    Witzel, Christoph; Franklin, Anna

    2014-04-01

    If the most typical red, yellow, green, and blue were particularly colorful (i.e., saturated), they would "jump out to the eye." This would explain why even fundamentally different languages have distinct color terms for these focal colors, and why unique hues play a prominent role in subjective color appearance. In this study, the subjective saturation of 10 colors around each of these focal colors was measured through a pairwise matching task. Results show that subjective saturation changes systematically across hues in a way that is strongly correlated to the visual gamut, and exponentially related to sensitivity but not to focal colors.

  7. Radiating dipoles in photonic crystals

    PubMed

    Busch; Vats; John; Sanders

    2000-09-01

    The radiation dynamics of a dipole antenna embedded in a photonic crystal are modeled by an initially excited harmonic oscillator coupled to a non-Markovian bath of harmonic oscillators representing the colored electromagnetic vacuum within the crystal. Realistic coupling constants based on the natural modes of the photonic crystal, i.e., Bloch waves and their associated dispersion relation, are derived. For simple model systems, well-known results such as decay times and emission spectra are reproduced. This approach enables direct incorporation of realistic band structure computations into studies of radiative emission from atoms and molecules within photonic crystals. We therefore provide a predictive and interpretative tool for experiments in both the microwave and optical regimes.

  8. Structural colors: from natural to artificial systems.

    PubMed

    Fu, Yulan; Tippets, Cary A; Donev, Eugenii U; Lopez, Rene

    2016-09-01

    Structural coloration has attracted great interest from scientists and engineers in recent years, owing to fascination with various brilliant examples displayed in nature as well as to promising applications of bio-inspired functional photonic structures and materials. Much research has been done to reveal and emulate the physical mechanisms that underlie the structural colors found in nature. In this article, we review the fundamental physics of many natural structural colors displayed by living organisms as well as their bio-inspired artificial counterparts, with emphasis on their connections, tunability strategies, and proposed applications, which aim to maximize the technological benefits one could derive from these photonic nanostructures. WIREs Nanomed Nanobiotechnol 2016, 8:758-775. doi: 10.1002/wnan.1396 For further resources related to this article, please visit the WIREs website.

  9. Noncontrast Peripheral MRA with Spiral Echo Train Imaging

    PubMed Central

    Fielden, Samuel W.; Mugler, John P.; Hagspiel, Klaus D.; Norton, Patrick T.; Kramer, Christopher M.; Meyer, Craig H.

    2015-01-01

    Purpose To develop a spin echo train sequence with spiral readout gradients with improved artery–vein contrast for noncontrast angiography. Theory Venous T2 becomes shorter as the echo spacing is increased in echo train sequences, improving contrast. Spiral acquisitions, due to their data collection efficiency, facilitate long echo spacings without increasing scan times. Methods Bloch equation simulations were performed to determine optimal sequence parameters, and the sequence was applied in five volunteers. In two volunteers, the sequence was performed with a range of echo times and echo spacings to compare with the theoretical contrast behavior. A Cartesian version of the sequence was used to compare contrast appearance with the spiral sequence. Additionally, spiral parallel imaging was optionally used to improve image resolution. Results In vivo, artery–vein contrast properties followed the general shape predicted by simulations, and good results were obtained in all stations. Compared with a Cartesian implementation, the spiral sequence had superior artery–vein contrast, better spatial resolution (1.2 mm2 versus 1.5 mm2), and was acquired in less time (1.4 min versus 7.5 min). Conclusion The spiral spin echo train sequence can be used for flow-independent angiography to generate threedimensional angiograms of the periphery quickly and without the use of contrast agents. PMID:24753164

  10. Radar echo from a flat conducting plate, near and far

    NASA Astrophysics Data System (ADS)

    Williams, C. S.

    1982-01-01

    Over certain types of terrain, a radar fuze (or altimeter), by virtue of the horizontal component of its velocity, is likely to pass over various flat objects of limited size. The echo from such objects could have a duration less than that of one Doppler cycle, where the Doppler frequency is due to the vertical component of the velocity. If the terrain is principally made up of such objects, their echoes are in most cases entirely uncorrelated with each other. Hence, the total echo after mixing at the radar with the delayed transmitted wave would have a noise-like spectrum not at all confined to the Doppler-frequency band where the desired echo signal is expected. This would seriously degrade the performance of a radar that utilizes correlation. This work shows that the echo from a square flat plate will be of duration greater than the time it takes to pass over the plate if the height h above it satisfies h a squared lambda where a is the plate-edge dimension and lambda is the radar wavelength. The results presented here can be used to determine the spatial region wherein the echo exists, and the magnitude and phase of the echo from such a plate.

  11. Radar echo from a flat conducting plate - near and far

    SciTech Connect

    Williams, C.S.

    1982-01-01

    Over certain types of terrain, a radar fuze (or altimeter), by virtue of the horizontal component of its velocity, is likely to pass over various flat objects of limited size. The echo from such objects could have a duration less than that of one Doppler cycle, where the Doppler frequency is due to the vertical component of the velocity. If the terrain is principally made up of such objects, their echoes are in most cases entirely uncorrelated with each other. Hence, the total echo after mixing at the radar with the delayed transmitted wave would have a noise-like spectrum not at all confined to the Doppler-frequency band where the desired echo signal is expected. This would seriously degrade the performance of a radar that utilizes correlation. This work shows that the echo from a square flat plate will be of duration greater than the time it takes to pass over the plate if the height h above it satisfies h > a/sup 2//lambda where a is the plate-edge dimension and lambda is the radar wavelength. The results presented here can be used to determine the spatial region wherein the echo exists, and the magnitude and phase of the echo from such a plate. I infer from these results that the case where the signal has a noise-like spectrum is not impossible but it is unlikely for the applications with which I am familiar.

  12. Green photonics

    NASA Astrophysics Data System (ADS)

    Quan, Frederic

    2012-02-01

    Photonics, the broad merger of electronics with the optical sciences, encompasses such a wide swath of technology that its impact is almost universal in our everyday lives. This is a broad overview of some aspects of the industry and their contribution to the ‘green’ or environmental movement. The rationale for energy conservation is briefly discussed and the impact of photonics on our everyday lives and certain industries is described. Some opinions from industry are presented along with market estimates. References are provided to some of the most recent research in these areas.

  13. Vesicle Photonics

    SciTech Connect

    Vasdekis, Andreas E.; Scott, E. A.; Roke, Sylvie; Hubbell, J. A.; Psaltis, D.

    2013-04-03

    Thin membranes, under appropriate boundary conditions, can self-assemble into vesicles, nanoscale bubbles that encapsulate and hence protect or transport molecular payloads. In this paper, we review the types and applications of light fields interacting with vesicles. By encapsulating light-emitting molecules (e.g. dyes, fluorescent proteins, or quantum dots), vesicles can act as particles and imaging agents. Vesicle imaging can take place also under second harmonic generation from vesicle membrane, as well as employing mass spectrometry. Light fields can also be employed to transport vesicles using optical tweezers (photon momentum) or directly pertrurbe the stability of vesicles and hence trigger the delivery of the encapsulated payload (photon energy).

  14. Photonic Bandgaps in Photonic Molecules

    NASA Technical Reports Server (NTRS)

    Smith, David D.; Chang, Hongrok; Gates, Amanda L.; Fuller, Kirk A.; Gregory, Don A.; Witherow, William K.; Paley, Mark S.; Frazier, Donald O.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    This talk will focus on photonic bandgaps that arise due to nearly free photon and tight-binding effects in coupled microparticle and ring-resonator systems. The Mie formulation for homogeneous spheres is generalized to handle core/shell systems and multiple concentric layers in a manner that exploits an analogy with stratified planar systems, thereby allowing concentric multi-layered structures to be treated as photonic bandgap (PBG) materials. Representative results from a Mie code employing this analogy demonstrate that photonic bands arising from nearly free photon effects are easily observed in the backscattering, asymmetry parameter, and albedo for periodic quarter-wave concentric layers, though are not readily apparent in extinction spectra. Rather, the periodicity simply alters the scattering profile, enhancing the ratio of backscattering to forward scattering inside the bandgap, in direct analogy with planar quarter-wave multilayers. PBGs arising from tight-binding may also be observed when the layers (or rings) are designed such that the coupling between them is weak. We demonstrate that for a structure consisting of N coupled micro-resonators, the morphology dependent resonances split into N higher-Q modes, in direct analogy with other types of oscillators, and that this splitting ultimately results in PBGs which can lead to enhanced nonlinear optical effects.

  15. First HF radar measurements of summer mesopause echoes at SURA

    NASA Astrophysics Data System (ADS)

    Karashtin, A. N.; Shlyugaev, Y. V.; Abramov, V. I.; Belov, I. F.; Berezin, I. V.; Bychkov, V. V.; Eryshev, E. B.; Komrakov, G. P.

    1997-07-01

    HF sounding of the mesosphere was first carried out at SURA in summer 1994 at frequencies in the range 8-9 MHz using one of the sub-arrays of the SURA heating facility. The observations had a range resolution of 3 km. Almost all measurements indicated the presence of strong radar returns from altitudes between 83 and 90 km with features very similar to VHF measurements of mesopause summer echoes at mid-latitudes and polar mesopause summer echoes. In contrast to VHF observations, HF mesopause echoes are almost always present.

  16. Temperature echoes revisited to probe the vibrational behavior of dendrimers

    NASA Astrophysics Data System (ADS)

    Paulo, Pedro M. R.

    2010-03-01

    Temperature quench echoes were induced in molecular dynamics simulations of dendrimers. This phenomenon was used to probe the vibrational behavior of these molecules by comparing simulation results with harmonic model predictions. The echo depth for short time intervals between temperature quenches is well described by the harmonic approximation and the fluctuations observed are related to the vibrational density of states. The echo depth for long time intervals decays progressively revealing dephasing due to anharmonic interactions. The density of states was calculated from the temperature fluctuations after the first quench and high-frequency modes were assigned by comparison with vibrational spectra of similar dendrimers.

  17. Temperature echoes revisited to probe the vibrational behavior of dendrimers.

    PubMed

    Paulo, Pedro M R

    2010-03-21

    Temperature quench echoes were induced in molecular dynamics simulations of dendrimers. This phenomenon was used to probe the vibrational behavior of these molecules by comparing simulation results with harmonic model predictions. The echo depth for short time intervals between temperature quenches is well described by the harmonic approximation and the fluctuations observed are related to the vibrational density of states. The echo depth for long time intervals decays progressively revealing dephasing due to anharmonic interactions. The density of states was calculated from the temperature fluctuations after the first quench and high-frequency modes were assigned by comparison with vibrational spectra of similar dendrimers.

  18. Optically tuneable blue phase photonic band gaps

    SciTech Connect

    Liu, H.-Y.; Wang, C.-T.; Hsu, C.-Y.; Lin, T.-H.; Liu, J.-H.

    2010-03-22

    This study investigates an optically switchable band gap of photonic crystal that is based on an azobenzene-doped liquid crystal blue phase. The trans-cis photoisomerization of azobenzene deforms the cubic unit cell of the blue phase and shifts the photonic band gap. The fast back-isomerization of azobenzene was induced by irradiation with different wavelengths light. The crystal structure is verified using Kossel diffraction diagram. An optically addressable blue phase display, based on Bragg reflection from the photonic band gap, is also demonstrated. The tunable ranges are around red, green, and blue wavelengths and exhibit a bright saturated color.

  19. Structural color and its interaction with other color-producing elements: perspectives from spiders

    NASA Astrophysics Data System (ADS)

    Hsiung, Bor-Kai; Blackledge, Todd A.; Shawkey, Matthew D.

    2014-09-01

    Structural color is produced when nanostructures called schemochromes alter light reflected from a surface through different optic principles, in contrast with other types of colors that are produced when pigments selectively absorb certain wavelengths of light. Research on biogenic photonic nanostructures has focused primarily on bird feathers, butterfly wings and beetle elytra, ignoring other diverse groups such as spiders. We argue that spiders are a good model system to study the functions and evolution of colors in nature for the following reasons. First, these colors clearly function in spiders such as the tarantulas outside of sexual selection, which is likely the dominant driver of the evolution of structural colors in birds and butterflies. Second, within more than 44,000 currently known spider species, colors are used in every possible way based on the same sets of relatively simple materials. Using spiders, we can study how colors evolve to serve different functions under a variety of combinations of driving forces, and how those colors are produced within a relatively simple system. Here, we first review the different color-producing materials and mechanisms (i.e., light absorbing, reflecting and emitting) in birds, butterflies and beetles, the interactions between these different elements, and the functions of colors in different organisms. We then summarize the current state of knowledge of spider colors and compare it with that of birds and insects. We then raise questions including: 1. Could spiders use fluorescence as a mechanism to protect themselves from UV radiation, if they do not have the biosynthetic pathways to produce melanins? 2. What functions could color serve for nearly blind tarantulas? 3. Why are only multilayer nanostructures (thus far) found in spiders, while birds and butterflies use many diverse nanostructures? And, does this limit the diversity of structural colors found in spiders? Answering any of these questions in the future

  20. Color Relationalism and Relativism.

    PubMed

    Byrne, Alex; Hilbert, David R

    2017-01-01

    This paper critically examines color relationalism and color relativism, two theories of color that are allegedly supported by variation in normal human color vision. We mostly discuss color relationalism, defended at length in Jonathan Cohen's The Red and the Real, and argue that the theory has insuperable problems.

  1. Primary Theme Club. Colors.

    ERIC Educational Resources Information Center

    Walmsley, Bonnie Brown; Camp, Anne-Marie

    1997-01-01

    Presents a cross-curricular theme unit on colors that includes a pullout poster and a resource list. Social studies activities highlight flags of the world. Science activities teach about colors of animals and the science of color. Language arts activities describe colorful language. Mathematics activities involve sorting and graphing colors. (SM)

  2. Activities: Some Colorful Mathematics.

    ERIC Educational Resources Information Center

    DeTemple, Duane W.; Walker, Dean A.

    1996-01-01

    Describes three activities in discrete mathematics that involve coloring geometric objects: counting colored regions of overlapping simple closed curves, counting colored triangulations of polygons, and determining the number of colors required to paint the plane so that no two points one inch apart are the same color. (MKR)

  3. First radar echoes from cumulus clouds

    NASA Technical Reports Server (NTRS)

    Knight, Charles A.; Miller, L. J.

    1993-01-01

    In attempting to use centimeter-wavelength radars to investigate the early stage of precipitation formation in clouds, 'mantle echoes' are rediscovered and shown to come mostly from scattering by small-scale variations in refractive index, a Bragg kind of scattering mechanism. This limits the usefulness of single-wavelength radar for studies of hydrometeor growth, according to data on summer cumulus clouds in North Dakota, Hawaii, and Florida, to values of reflectivity factor above about 10 dBZe with 10-cm radar, 0 dBZe with 5-cm radar, and -10 dBZe with 3-cm radar. These are limits at or above which the backscattered radar signal from the kinds of clouds observed can be assumed to be almost entirely from hydrometeors or (rarely) other particulate material such as insects. Dual-wavelength radar data can provide the desired information about hydrometeors at very low reflectivity levels if assumptions can be made about the inhomogeneities responsible for the Bragg scattering. The Bragg scattering signal itself probably will be a useful way to probe inhomogeneities one-half the radar wavelength in scale for studying cloud entrainment and mixing processes. However, this use is possible only before scattering from hydrometeors dominates the radar return.

  4. CRITICAL CARE ECHO ROUNDS: Haemodynamic instability

    PubMed Central

    Francisco, Nadia; Rendon, Alejandro; Gillon, Stuart; Walker, David

    2014-01-01

    The use of echocardiography, whilst well established in cardiology, is a relatively new concept in critical care medicine. However, in recent years echocardiography's potential as both a diagnostic tool and a form of advanced monitoring in the critically ill patient has been increasingly recognised. In this series of Critical Care Echo Rounds, we explore the role of echocardiography in critical illness, beginning here with haemodynamic instability. We discuss the pathophysiology of the shock state, the techniques available to manage haemodynamic compromise, and the unique role which echocardiography plays in this complex process. Case A 69-year-old female presents to the emergency department with a fever, confusion and pain on urinating. Her blood pressure on arrival was 70/40, with heart rate of 117 bpm Despite 3 l of i.v. fluid she remained hypotensive. A central venous catheter was inserted and noradrenaline infusion commenced, and she was admitted to the intensive care unit for management of her shock state. At 6 h post admission, she was on high dose of noradrenaline (0.7 μg/kg per min) but blood pressure remained problematic. An echocardiogram was requested to better determine her haemodynamic state. PMID:26693291

  5. Factors Influencing Ultrasound Echoes From Arterial Walls

    NASA Astrophysics Data System (ADS)

    Griffith, Jim; Maciel, Mario; Zalesky, Paul

    1988-04-01

    Significant progress in methods for the treatment of arterial disease has been made during the past several years. The trend towards least invasive therapies has led to an increasing need for instruments which quantify arterial disease status before, during, and after an intervention or treatment. Such instruments should provide safer and more effective disease treatment by providing the physician with a procedure guidance tool. The use of miniature ultrasound transducers, mounted at the distal end of a vascular catheter or probe, offers a promising method for producing images and quantitative measure-ment of arterial lumen and wall thickness. Several approaches have been suggested for placing the transducers in a probe configuration which is then mounted in a catheter and advanced to the vascular site of interest for image generation. The "best" probe configuration is defined by the specific questions of interest to the physician. It also depends upon transducer characteristics and how the sound beam "interacts" with the arterial wall. Imaging the small diameter coronary arteries, in particular, requires careful consideration of various transducer-tissue parameters. Transducer signal-to-noise ratio will likely be a critical parameter for systems designed to image healthy and diseased coronary arteries. The reported study shows how arterial wall echo amplitude changes as the angle between sound beam and wall varies. Changes are measured under carefully defined laboratory conditions.

  6. Light Echoes of Galactic Explosions and Eruptions

    NASA Astrophysics Data System (ADS)

    Rest, Armin; Bianco, Federica; Chornock, Ryan; Foley, Ryan; Huber, Mark E.; Matheson, Thomas; McDonald, Brittany; Olsen, Knut; Prieto, Jose Luis; Sinnott, Brendan; Smith, Nathan; Welch, Doug

    2012-08-01

    We propose to search for light echoes (LEs) from the historical brightening of the Luminous Blue Variable (LBV) P Cygni using the KPNO 4m Mosaic 1.1 imager. We also propose to conclude our search - so far unsuccessful - for LEs from the the Crab supernova SN 1054 by surveying one remaining region of the LE ellipsoid behind the plane of the supernova remnant on the sky. In addition, we continue to monitor the LEs from the Cas A and Tycho supernovae in order to identify suitable LE candidates for 3D-spectroscopy and spectral time series. Recently, we discovered LEs of the mid-19th-century Great Eruption of η Carinae using CTIO 4m Mosaic images. Subsequent spectroscopic follow-up revealed that its outburst spectral type was most similar to those of G-type supergiants, rather than the reported LBV outburst spectral types (F-type or earlier) teRest12_eta. The application of the LE studies to LBVs promises to extend our ability to record outburst activity hundreds of years into the past - a timescale which is likely a significant fraction of the brief final phases of these probable core-collapse supernova precursors.

  7. 122. AERIAL VIEW OF GLEN ECHO AND CLARA BARTON PARKWAY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    122. AERIAL VIEW OF GLEN ECHO AND CLARA BARTON PARKWAY AND MACARTHUR BLVD. INTERCHANGE LOOKING NORTHWEST. - George Washington Memorial Parkway, Along Potomac River from McLean to Mount Vernon, VA, Mount Vernon, Fairfax County, VA

  8. Statistical Characterization of the Medical Ultrasound Echo Signals

    NASA Astrophysics Data System (ADS)

    Cai, Runqiu

    2016-12-01

    Medical ultrasound echo signals provide the basic information for obtaining the ultrasonic image in medical ultrasound technology. The statistics of the ultrasound echo signals reveals the systematic structure of the medical ultrasonic image via analyzing the corresponding statistical distributions. A novel statistical distribution, the ascending order K distribution, was proposed here to model the medical ultrasound echo signals. The ascending order K distribution was developed in light of the statistical analysis of the sequential waveforms in the echo signals. Comparison with the previous statistical distributions was made to verify the superiority of the ascending order K distribution. Further discussion showed the determination of the statistical principles for the ultrasound signals can enhance our understanding of the statistical principles of the ultrasound imaging, and thus, facilitate the optimization of the ultrasound image and the tissue identification in the ultrasound diagnosis.

  9. Light echoes and transient luminescence near SN 1987A

    NASA Technical Reports Server (NTRS)

    Crotts, Arlin P. S.; Kunkel, William E.; Mccarthy, Patrick J.

    1989-01-01

    The discovery of two new light echoes from sheets of material behind supernova 1987A and present images of the progenitor's circumstellar shell are reported, indicating diffuse echoes from the star's red giant wind. The echo sheets' geometry explains well the behavior of SN 1987's 10-micron flux, but the circumstellar shell appears to be 70 percent larger than the prediction from the analysis of narrow UV emission lines. The sheets' recombination time show them relatively thin and dense. The data also constrain the existence of any fourth star in the Sanduleak -69 deg 202 system and show that the feature reported 8 arcsecs from the supernova is probably not an echo from a thin sheet in SN 1987A's foreground.

  10. Detecting faint echoes in stellar-flare light curves

    NASA Technical Reports Server (NTRS)

    Bromley, Benjamin C.

    1992-01-01

    Observational considerations are discussed for detecting echoes from flare-star photospheres and from stellar or planetary companions. Synthetic spectra are used to determine optimal conditions for the recovery of echoes in flare light curves. The most detectable echoes are expected to appear in broadband observations of the UV continuum. Short-lived flares are ideal for resolving echoes from the flare-star photosphere and may provide constraints for stellar-flare models. Strong outbursts may be used to detect stellar or planetary companions of a flare star. However, the possible planetary configurations that may be probed by this method are limited to Jupiter-size objects in tight orbits about the parent star.

  11. Statistical Characterization of the Medical Ultrasound Echo Signals

    PubMed Central

    Cai, Runqiu

    2016-01-01

    Medical ultrasound echo signals provide the basic information for obtaining the ultrasonic image in medical ultrasound technology. The statistics of the ultrasound echo signals reveals the systematic structure of the medical ultrasonic image via analyzing the corresponding statistical distributions. A novel statistical distribution, the ascending order K distribution, was proposed here to model the medical ultrasound echo signals. The ascending order K distribution was developed in light of the statistical analysis of the sequential waveforms in the echo signals. Comparison with the previous statistical distributions was made to verify the superiority of the ascending order K distribution. Further discussion showed the determination of the statistical principles for the ultrasound signals can enhance our understanding of the statistical principles of the ultrasound imaging, and thus, facilitate the optimization of the ultrasound image and the tissue identification in the ultrasound diagnosis. PMID:27991564

  12. Ferrofluid Photonic Dipole Contours

    NASA Astrophysics Data System (ADS)

    Snyder, Michael; Frederick, Jonathan

    2008-03-01

    Understanding magnetic fields is important to facilitate magnetic applications in diverse fields in industry, commerce, and space exploration to name a few. Large electromagnets can move heavy loads of metal. Magnetic materials attached to credit cards allow for fast, accurate business transactions. And the Earth's magnetic field gives us the colorful auroras observed near the north and south poles. Magnetic fields are not visible, and therefore often hard to understand or characterize. This investigation describes and demonstrates a novel technique for the visualization of magnetic fields. Two ferrofluid Hele-Shaw cells have been constructed to facilitate the imaging of magnetic field lines [1,2,3,4]. We deduce that magnetically induced photonic band gap arrays similar to electrostatic liquid crystal operation are responsible for the photographed images and seek to mathematically prove the images are of exact dipole nature. We also note by comparison that our photographs are very similar to solar magnetic Heliosphere photographs.

  13. Photon Collider Physics with Real Photon Beams

    SciTech Connect

    Gronberg, J; Asztalos, S

    2005-11-03

    Photon-photon interactions have been an important probe into fundamental particle physics. Until recently, the only way to produce photon-photon collisions was parasitically in the collision of charged particles. Recent advances in short-pulse laser technology have made it possible to consider producing high intensity, tightly focused beams of real photons through Compton scattering. A linear e{sup +}e{sup -} collider could thus be transformed into a photon-photon collider with the addition of high power lasers. In this paper they show that it is possible to make a competitive photon-photon collider experiment using the currently mothballed Stanford Linear Collider. This would produce photon-photon collisions in the GeV energy range which would allow the discovery and study of exotic heavy mesons with spin states of zero and two.

  14. Color vision and color formation in dragonflies.

    PubMed

    Futahashi, Ryo

    2016-10-01

    Dragonflies including damselflies are colorful and large-eyed insects, which show remarkable sexual dimorphism, color transition, and color polymorphism. Recent comprehensive visual transcriptomics has unveiled an extraordinary diversity of opsin genes within the lineage of dragonflies. These opsin genes are differentially expressed between aquatic larvae and terrestrial adults, as well as between dorsal and ventral regions of adult compound eyes. Recent topics of color formation in dragonflies are also outlined. Non-iridescent blue color is caused by coherent light scattering from the quasiordered nanostructures, whereas iridescent color is produced by multilayer structures. Wrinkles or wax crystals sometimes enhances multilayer structural colors. Sex-specific and stage-specific color differences in red dragonflies is attributed to redox states of ommochrome pigments.

  15. How New National Air Data System Affects ECHO Data ...

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  16. NPDES Program Search Criteria Help | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  17. Preliminary results of the echo-seeding experiment at SLAC

    SciTech Connect

    Xiang, D.; Colby, E.; Ding, Y.; Dunning, M.; Frederico, J.; Gilevich, S.; Hast, C.; Jobe, K.; McCormick, D.; Nelson, J.; Raubenheimer, T.O.; Soong, K.; Stupakov, G.; Szalata, Z.; Walz, D.; Weathersby, S.; Woodley, M.; Corlett, J.; Qiang, J.; Penn, G.; Prestemon, S.; Schlueter, R.; Venturini, M.; Wan, W.; Pernet, P-L.

    2010-05-23

    ECHO-7 is a proof-of-principle echo-enabled harmonic generation FEL experiment in the Next Linear Collider Test Accelerator (NLCTA) at SLAC. The experiment aims to generate coherent radiation at 318 nm and 227 nm, which are the 5th and 7th harmonic of the infrared seed laser. In this paper we present the preliminary results from the commissioning run of the completed experimental setup which started in April 2010.

  18. Analyze Trends: Drinking Water Dashboard | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  19. ECHO Services: Foundational Middleware for a Science Cyberinfrastructure

    NASA Technical Reports Server (NTRS)

    Burnett, Michael

    2005-01-01

    This viewgraph presentation describes ECHO, an interoperability middleware solution. It uses open, XML-based APIs, and supports net-centric architectures and solutions. ECHO has a set of interoperable registries for both data (metadata) and services, and provides user accounts and a common infrastructure for the registries. It is built upon a layered architecture with extensible infrastructure for supporting community unique protocols. It has been operational since November, 2002 and it available as open source.

  20. Analyze Trends: State Air Dashboard | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  1. Civil Enforcement Case Report Data Dictionary | ECHO | US ...

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  2. Analyze Trends: State Water Dashboard | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  3. ICIS-Air Program Code Subpart Descriptions | ECHO | US ...

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  4. State Comments on Frozen Data - 2014 | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  5. Facility Search – Enforcement and Compliance Data | ECHO ...

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  6. Criminal Enforcement Case Report Help | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  7. Civil Enforcement Case Report Help | ECHO | US EPA

    EPA Pesticide Factsheets

    ECHO, Enforcement and Compliance History Online, provides compliance and enforcement information for approximately 800,000 EPA-regulated facilities nationwide. ECHO includes permit, inspection, violation, enforcement action, and penalty information about facilities regulated under the Clean Air Act (CAA) Stationary Source Program, Clean Water Act (CWA) National Pollutant Elimination Discharge System (NPDES), and/or Resource Conservation and Recovery Act (RCRA). Information also is provided on surrounding demographics when available.

  8. Urine - abnormal color

    MedlinePlus

    ... medlineplus.gov/ency/article/003139.htm Urine - abnormal color To use the sharing features on this page, please enable JavaScript. The usual color of urine is straw-yellow. Abnormally colored urine ...

  9. Tooth - abnormal colors

    MedlinePlus

    ... medlineplus.gov/ency/article/003065.htm Tooth - abnormal colors To use the sharing features on this page, please enable JavaScript. Abnormal tooth color is any color other than white to yellowish- ...

  10. LED Color Characteristics

    SciTech Connect

    2012-01-01

    Color quality is an important consideration when evaluating LED-based products for general illumination. This fact sheet reviews the basics regarding light and color and summarizes the most important color issues related to white-light LED systems.

  11. Color Blindness Simulations

    MedlinePlus

    ... Coordinator Color blindness Simulations Normal Color Vision Deuteranopia Color blindness marked by confusion of purplish red and green Tritanopia A dichromatism in which the spectrum is seen in tones of red and green. ...

  12. Significance-aware filtering for nonlinear acoustic echo cancellation

    NASA Astrophysics Data System (ADS)

    Hofmann, Christian; Huemmer, Christian; Guenther, Michael; Kellermann, Walter

    2016-12-01

    This article summarizes and extends the recently proposed concept of Significance-Aware (SA) filtering for nonlinear acoustic echo cancellation. The core idea of SA filtering is to decompose the estimation of the nonlinear echo path into beneficially interacting subsystems, each of which can be adapted with high computational efficiency. The previously proposed SA Hammerstein Group Models (SA-HGMs) decompose the nonlinear acoustic echo path into a direct-path part, modeled by a Hammerstein Group Model (HGM) and a complementary part, modeled by a very efficient Hammerstein model. In this article, we furthermore propose a novel Equalization-based SA (ESA) structure, where the echo path is equalized by a linear filter to allow for an estimation of the loudspeaker nonlinearities by very small and efficient models. Additionally, we provide a novel in-depth analysis of the computational complexity of the previously proposed SA and the novel ESA filters and compare both SA filtering approaches to each other, to adaptive HGMs, and to linear filters, where fast partitioned-block frequency-domain realizations of the competing filter structures are considered. Finally, the echo reduction performance of the proposed SA filtering approaches is verified using real recordings from a commercially available smartphone. Beyond the scope of previous publications on SA-HGMs, the ability of the SA filters to generalize for double-talk situations is explicitly considered as well. The low complexity as well as the good echo reduction performance of both SA filters illustrate the potential of SA filtering in practice.

  13. Velocities of auroral coherent echoes at 12 and 144 MHz

    NASA Astrophysics Data System (ADS)

    Koustov, A. V.; Danskin, D. W.; Uspensky, M. V.; Ogawa, T.; Janhunen, P.; Nishitani, N.; Nozawa, S.; Lester, M.; Milan, S.

    2002-10-01

    Two Doppler coherent radar systems are currently working at Hankasalmi, Finland, the STARE and CUTLASS radars operating at ~144 MHz and ~12 MHz, respectively. The STARE beam 3 is nearly co-located with the CUTLASS beam 5, providing an opportunity for echo velocity comparison along the same direction but at significantly different radar frequencies. In this study we consider an event when STARE radar echoes are detected at the same ranges as CUT-LASS radar echoes. The observations are complemented by EISCAT measurements of the ionospheric electric field and electron density behaviour at one range of 900 km. Two separate situations are studied; for the first one, CUTLASS observed F-region echoes (including the range of the EIS-CAT measurements), while for the second one CUTLASS observed E-region echoes. In both cases STARE E-region measurements were available. We show that F-region CUT-LASS velocities agree well with the convection component along the CUTLASS radar beam, while STARE velocities are typically smaller by a factor of 2 3. For the second case, STARE velocities are found to be either smaller or larger than CUTLASS velocities, depending on the range. Plasma physics of E-and F-region irregularities is discussed in attempt to explain the inferred relationship between various velocities. Special attention is paid to ionospheric refraction that is important for the detection of 12-MHz echoes.

  14. Quantum teleportation from a propagating photon to a solid-state spin qubit.

    PubMed

    Gao, W B; Fallahi, P; Togan, E; Delteil, A; Chin, Y S; Miguel-Sanchez, J; Imamoğlu, A

    2013-01-01

    A quantum interface between a propagating photon used to transmit quantum information and a long-lived qubit used for storage is of central interest in quantum information science. A method for implementing such an interface between dissimilar qubits is quantum teleportation. Here we experimentally demonstrate transfer of quantum information carried by a photon to a semiconductor spin using quantum teleportation. In our experiment, a single photon in a superposition state is generated using resonant excitation of a neutral dot. To teleport this photonic qubit, we generate an entangled spin-photon state in a second dot located 5 m away and interfere the photons from the two dots in a Hong-Ou-Mandel set-up. Thanks to an unprecedented degree of photon-indistinguishability, a coincidence detection at the output of the interferometer heralds successful teleportation, which we verify by measuring the resulting spin state after prolonging its coherence time by optical spin-echo.

  15. Quantum teleportation from a propagating photon to a solid-state spin qubit

    NASA Astrophysics Data System (ADS)

    Gao, W. B.; Fallahi, P.; Togan, E.; Delteil, A.; Chin, Y. S.; Miguel-Sanchez, J.; Imamoğlu, A.

    2013-11-01

    A quantum interface between a propagating photon used to transmit quantum information and a long-lived qubit used for storage is of central interest in quantum information science. A method for implementing such an interface between dissimilar qubits is quantum teleportation. Here we experimentally demonstrate transfer of quantum information carried by a photon to a semiconductor spin using quantum teleportation. In our experiment, a single photon in a superposition state is generated using resonant excitation of a neutral dot. To teleport this photonic qubit, we generate an entangled spin-photon state in a second dot located 5 m away and interfere the photons from the two dots in a Hong-Ou-Mandel set-up. Thanks to an unprecedented degree of photon-indistinguishability, a coincidence detection at the output of the interferometer heralds successful teleportation, which we verify by measuring the resulting spin state after prolonging its coherence time by optical spin-echo.

  16. Microalgae photonics

    NASA Astrophysics Data System (ADS)

    Floume, Timmy; Coquil, Thomas; Sylvestre, Julien

    2011-05-01

    Due to their metabolic flexibility and fast growth rate, microscopic aquatic phototrophs like algae have a potential to become industrial photochemical converters. Algae photosynthesis could enable the large scale production of clean and renewable liquid fuels and chemicals with major environmental, economic and societal benefits. Capital and operational costs are the main issues to address through optical, process and biochemical engineering improvements. In this perspective, a variety of photonic approaches have been proposed - we introduce them here and describe their potential, limitations and compatibility with separate biotechnology and engineering progresses. We show that only sunlight-based approaches are economically realistic. One of photonics' main goals in the algae field is to dilute light to overcome photosaturation effects that impact upon cultures exposed to full sunlight. Among other approaches, we introduce a widely-compatible broadband spectral adaptation technique called AlgoSun® that uses luminescence to optimize sunlight spectrum in view of the bioconverter's requirements.

  17. Self-diffusion in nanopores studied by the NMR pulse gradient spin echo

    NASA Astrophysics Data System (ADS)

    Stepišnik, Janez; Fritzinger, Bernd; Scheler, Ulrich; Mohorič, Aleš

    2012-06-01

    NMR pulse gradient spin echo is the most efficient method for non-invasive elucidation of molecular transport in heterogeneous media. With a proper interpretation of experimental data, the method can also be applied to investigate molecular self-diffusion in pores small enough that the characteristic diffusion times are much shorter than time, needed to build up the spin phase structure by the pulse of magnetic field gradient. This is demonstrated by the analysis of restricted self-diffusion measurement of water molecules trapped in a polyamide membrane. The results are presented as a distribution of spin-relaxation rates and pore sizes in this nanoporous system that also present the method in its true colors as a useful tool in the bio-nanotechology.

  18. Photon detectors

    SciTech Connect

    Va`vra, J.

    1995-10-01

    J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF{sub 2} windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission.

  19. Photonic homeostatics

    NASA Astrophysics Data System (ADS)

    Liu, Timon C.; Li, Fan-Hui

    2010-11-01

    Photonic homeostatics is a discipline to study the establishment, maintenance, decay, upgrading and representation of function-specific homoestasis (FSH) by using photonics. FSH is a negative-feedback response of a biosystem to maintain the function-specific fluctuations inside the biosystem so that the function is perfectly performed. A stress may increase sirtuin 1 (SIRT1) activities above FSH-specific SIRT1 activity to induce a function far from its FSH. On the one hand, low level laser irradiation or monochromatic light (LLL) can not modulate a function in its FSH or a stress in its stress-specific homeostasis (StSH), but modulate a function far from its FSH or a stress far from its StSH. On the other hand, the biophotons from a biosystem with its function in its FSH should be less than the one from the biosystem with its function far from its FSH. The non-resonant interaction of low intensity laser irradiation or monochromatic light (LIL) and a kind of membrane protein can be amplified by all the membrane proteins if the function is far from its FSH. This amplification might hold for biophoton emission of the membrane protein so that the photonic spectroscopy can be used to represent the function far from its FSH, which is called photonomics.

  20. Resolution of overlapping ultrasonic echoes using consistent frequency domain amplitude-phase relationships

    NASA Astrophysics Data System (ADS)

    Kwan, Chi-Hang; Sinclair, Anthony N.

    2017-02-01

    We introduce a new post-processing ultrasonic echo identification algorithm for the special case of two overlapping echoes. Compared to dictionary-based deconvolution, the algorithm has a reduced solution space and can reconstruct echoes that have a better fit with the acquired data. We have tested the algorithm using a synthetic test case using two dissimilar echoes and the algorithm was able to reconstruct the constituent echoes with good accuracy.

  1. Cortical neurons of bats respond best to echoes from nearest targets when listening to natural biosonar multi-echo streams

    PubMed Central

    Beetz, M. Jerome; Hechavarría, Julio C.; Kössl, Manfred

    2016-01-01

    Bats orientate in darkness by listening to echoes from their biosonar calls, a behaviour known as echolocation. Recent studies showed that cortical neurons respond in a highly selective manner when stimulated with natural echolocation sequences that contain echoes from single targets. However, it remains unknown how cortical neurons process echolocation sequences containing echo information from multiple objects. In the present study, we used echolocation sequences containing echoes from three, two or one object separated in the space depth as stimuli to study neuronal activity in the bat auditory cortex. Neuronal activity was recorded with multi-electrode arrays placed in the dorsal auditory cortex, where neurons tuned to target-distance are found. Our results show that target-distance encoding neurons are mostly selective to echoes coming from the closest object, and that the representation of echo information from distant objects is selectively suppressed. This suppression extends over a large part of the dorsal auditory cortex and may override possible parallel processing of multiple objects. The presented data suggest that global cortical suppression might establish a cortical “default mode” that allows selectively focusing on close obstacle even without active attention from the animals. PMID:27786252

  2. Diffractive parameric colors.

    PubMed

    Orava, Joni; Heikkila, Noora; Jaaskelainen, Timo; Parkkinen, Jussi

    2008-12-01

    A method of producing inkless parameric color pairs is studied. In this method, colors are formed additively using diffraction gratings with differing grating periods as primary colors. Gratings with different grating periods reflect different spectral radiance peaks of a fluorescent lamp to the desired viewing angle, according to the grating equation. Four spectral peaks of a 4000 K fluorescent lamp--red, green, cyan, and blue-are used as the primary colors. The colors are mixed additively by fixing the relative areas of different grating periods inside a pixel. With four primary colors it is possible to mix certain colors with different triplets of primary colors. Thus, it is theoretically possible to produce metameric colors. In this study, three parameric color pairs are fabricated using electron beam lithography, electroplating, and hot embossing. The radiance spectra of the color pairs are measured by spectroradiometer from hot-embossed plastic samples. The CIELAB DeltaE(ab) and CIEDE2000 color differences between radiance spectra of the color pairs are calculated. The CIEDE2000 color differences of color pairs are between 2.6 and 7.2 units in reference viewing conditions. The effects of viewing angle and different light sources are also evaluated. It is found that both the viewing angle and the light source have very strong influences on the color differences of the color pairs.

  3. Uniform color space based on color matching

    NASA Astrophysics Data System (ADS)

    Liao, Shih-Fang; Yang, Tsung-Hsun; Lee, Cheng-Chung

    2007-09-01

    This research intends to explore with a uniform color space based on the CIE 1931 x-y chromatic coordinate system. The goal is to improve the non-uniformity of the CIE 1931 x-y chromaticity diagram such as to approach the human color sensation as possible; however, its simple methodology still can be kept. In spite of the existence of various kinds of the uniform color coordinate systems built up early (CIE u'-v', CIE Lab, CIE LUV, etc.), the establishment of a genuine uniform color space is actually still an important work both for the basic research in color science and the practical applications of colorimetry, especially for recent growing request in illumination engineering and in display technology. In this study, the MacAdam ellipses and the Munsell color chips are utilized for the comparison with the human color sensation. One specific linear transformation matrix is found for the CIE 1931 color matching functions (see manuscript) to become the novel uniform ones. With the aid of the optimization method, the transformation matrix can be easily discovered and makes the 25 MacAdam ellipses are similar to each other in the novel uniform color space. On the other hand, the perfectiveness of the equal-hue curves and the equal-chroma contours from the Mnusell color chips evaluates for the best optimization conditions among several different definitions for the similarity of all the MacAdam ellipses. Finally, the color difference between any two colors can be simply measured by the Euclidean distance in the novel uniform color space and is still fitted to the human color sensation.

  4. Revealing Invisible Photonic Inscriptions: Images from Strain

    PubMed Central

    2015-01-01

    Photonic structural materials have received intensive interest and have been strongly developed over the past few years for image displays, sensing, and anticounterfeit materials. Their “smartness” arises from their color responsivity to changes of environment, strain, or external fields. Here, we introduce a novel invisible photonic system that reveals encrypted images or characters by simply stretching, or immersing in solvents. This type of intriguing photonic material is composed of regularly arranged core–shell particles that are selectively cross-linked by UV irradiation, giving different strain response compared to un-cross-linked regions. The images reversibly appear and disappear when cycling the strain and releasing it. The unique advantages of this soft polymer opal system compared with other types of photonic gels are that it can be produced in roll to roll quantities, can be vigorously deformed to achieve strong color changes, and has no solvent evaporation issues because it is a photonic rubber system. We demonstrate potential applications together with a fabrication procedure which is straightforward and scalable, vital for user take-up. Our work deepens understanding of this rubbery photonic system based on core–shell nanospheres. PMID:26039279

  5. Pointillist structural color in Pollia fruit.

    PubMed

    Vignolini, Silvia; Rudall, Paula J; Rowland, Alice V; Reed, Alison; Moyroud, Edwige; Faden, Robert B; Baumberg, Jeremy J; Glover, Beverley J; Steiner, Ullrich

    2012-09-25

    Biological communication by means of structural color has existed for at least 500 million years. Structural color is commonly observed in the animal kingdom, but has been little studied in plants. We present a striking example of multilayer-based strong iridescent coloration in plants, in the fruit of Pollia condensata. The color is caused by Bragg reflection of helicoidally stacked cellulose microfibrils that form multilayers in the cell walls of the epicarp. We demonstrate that animals and plants have convergently evolved multilayer-based photonic structures to generate colors using entirely distinct materials. The bright blue coloration of this fruit is more intense than that of any previously described biological material. Uniquely in nature, the reflected color differs from cell to cell, as the layer thicknesses in the multilayer stack vary, giving the fruit a striking pixelated or pointillist appearance. Because the multilayers form with both helicoidicities, optical characterization reveals that the reflected light from every epidermal cell is polarized circularly either to the left or to the right, a feature that has never previously been observed in a single tissue.

  6. LEGUS Discovery of a Light Echo Around Supernova 2012aw

    NASA Astrophysics Data System (ADS)

    Van Dyk, Schuyler D.; Lee, Janice C.; Anderson, Jay; Andrews, Jennifer E.; Calzetti, Daniela; Bright, Stacey N.; Ubeda, Leonardo; Smith, Linda J.; Sabbi, Elena; Grebel, Eva K.; Herrero, Artemio; de Mink, Selma E.

    2015-06-01

    We have discovered a luminous light echo around the normal Type II-Plateau Supernova (SN) 2012aw in Messier 95 (M95; NGC 3351), detected in images obtained approximately two years after explosion with the Wide Field Channel 3 on board the Hubble Space Telescope by the Legacy ExtraGalactic Ultraviolet Survey. The multi-band observations span from the near-ultraviolet through the optical (F275W, F336W, F438W, F555W, and F814W). The apparent brightness of the echo at the time was ˜21-22 mag in all of these bands. The echo appears circular, although less obviously as a ring, with an inhomogeneous surface brightness, in particular, a prominent enhanced brightness to the southeast. The SN itself was still detectable, particularly in the redder bands. We are able to model the light echo as the time-integrated SN light scattered off of diffuse interstellar dust in the SN environment. We have assumed that this dust is analogous to that in the Milky Way with {R}V=3.1. The SN light curves that we consider also include models of the unobserved early burst of light from the SN shock breakout. Our analysis of the echo suggests that the distance from the SN to the scattering dust elements along the echo is ≈ 45 pc. The implied visual extinction for the echo-producing dust is consistent with estimates made previously from the SN itself. Finally, our estimate of the SN brightness in F814W is fainter than that measured for the red supergiant star at the precise SN location in pre-SN images, possibly indicating that the star has vanished and confirming it as the likely SN progenitor.

  7. Colored dual-functional photovoltaic cells

    NASA Astrophysics Data System (ADS)

    Lee, Kyu-Tae; Lee, Jae Yong; Xu, Ting; Park, Hui Joon; Guo, L. Jay

    2016-06-01

    In this article, we review our recent efforts on multi-functional photovoltaic (PV) cells that can produce desired reflective, transmissive, or neutral colors, by controlling light interaction with semiconductors and electrode structures in a desired manner. The PV cells integrated with plasmonic color filtering schemes using subwavelength gratings, and other approaches exploiting photonic resonances in an optical nanocavity consisting of highly absorbing semiconductor media are described. For further enhancement of optical and electrical performance characteristics of the multi-functional PV cells, possible difficulties and the outlook for future work are discussed.

  8. A high success rate full-waveform lidar echo decomposition method

    NASA Astrophysics Data System (ADS)

    Xu, Lijun; Li, Duan; Li, Xiaolu

    2016-01-01

    A full-waveform Light detection and ranging (LiDAR) echo decomposition method is proposed in this paper. In this method, the peak points are used to detect the separated echo components, while the inflection points are combined with corresponding peak points to detect the overlapping echo components. The detected echo components are then sorted according to their energies in a descending order. The sorted echo components are one by one added into the decomposition model according to their orders. For each addition, the parameters of all echo components already added into the decomposition model are iteratively renewed. After renewing, the amplitudes and full width at half maximums of the echo components are compared with pre-set thresholds to determine and remove the false echo components. Both simulation and experiment were carried out to evaluate the proposed method. In simulation, 4000 full-waveform echoes with different numbers and parameters of echo components were generated and decomposed using the proposed and three other commonly used methods. Results show that the proposed method is of the highest success rate, 91.43%. In experiment, 9549 Geoscience Laser Altimeter System (GLAS) echoes for Shennongjia forest district in south China were employed as test echoes. The test echoes were first decomposed using the four methods and the decomposition results were also compared with those provided by the National Snow and Ice Data Center. Comparison results show that the determination coefficient ({{R}2} ) of the proposed method is of the largest mean, 0.6838, and the smallest standard deviation, 0.3588, and the distribution of the number of the echo components decomposed from the GLAS echoes is the most satisfied with the situation of full-waveform echoes from the forest area, implying that the superposition of the echo components decomposed from a full-waveform echo by using the proposed method can best approximate the full-waveform echo.

  9. Single-shot echo-planar imaging with Nyquist ghost compensation: interleaved dual echo with acceleration (IDEA) echo-planar imaging (EPI).

    PubMed

    Poser, Benedikt A; Barth, Markus; Goa, Pål-Erik; Deng, Weiran; Stenger, V Andrew

    2013-01-01

    Echo planar imaging (EPI) is most commonly used for blood oxygen level-dependent fMRI, owing to its sensitivity and acquisition speed. A major problem with EPI is Nyquist (N/2) ghosting, most notably at high field. EPI data are acquired under an oscillating readout gradient and hence vulnerable to gradient imperfections such as eddy current delays and off-resonance effects, as these cause inconsistencies between odd and even k-space lines after time reversal. We propose a straightforward and pragmatic method herein termed "interleaved dual echo with acceleration (IDEA) EPI": two k-spaces (echoes) are acquired under the positive and negative readout lobes, respectively, by performing phase encoding blips only before alternate readout gradients. From these two k-spaces, two almost entirely ghost free images per shot can be constructed, without need for phase correction. The doubled echo train length can be compensated by parallel imaging and/or partial Fourier acquisition. The two k-spaces can either be complex averaged during reconstruction, which results in near-perfect cancellation of residual phase errors, or reconstructed into separate images. We demonstrate the efficacy of IDEA EPI and show phantom and in vivo images at both 3 T and 7 T.

  10. Color identification testing device

    NASA Technical Reports Server (NTRS)

    Brawner, E. L.; Martin, R.; Pate, W.

    1970-01-01

    Testing device, which determines ability of a technician to identify color-coded electric wires, is superior to standard color blindness tests. It tests speed of wire selection, detects partial color blindness, allows rapid testing, and may be administered by a color blind person.

  11. Color Me Understood.

    ERIC Educational Resources Information Center

    Harris, Judy J.

    2000-01-01

    Describes the "color system" as a way of grouping children into different personality types based on a certain color: orange, blue, green, and gold. Lists stress producers for specific color people. Asserts that, through making groups of different colors, children begin to see the various specialties others can bring to the group and learn to…

  12. Digital Color Image Restoration

    DTIC Science & Technology

    1975-08-01

    color image recording system is derived and the equations representing the model and the equations of colorimetry are expressed in matrix form. Computer ... algorithms are derived which correct color errors introduced by imperfections in the color recording system. The sources of color error which are

  13. Photonic Nanojets.

    PubMed

    Heifetz, Alexander; Kong, Soon-Cheol; Sahakian, Alan V; Taflove, Allen; Backman, Vadim

    2009-09-01

    This paper reviews the substantial body of literature emerging since 2004 concerning photonic nanojets. The photonic nanojet is a narrow, high-intensity, non-evanescent light beam that can propagate over a distance longer than the wavelength λ after emerging from the shadow-side surface of an illuminated lossless dielectric microcylinder or microsphere of diameter larger than λ. The nanojet's minimum beamwidth can be smaller than the classical diffraction limit, in fact as small as ~λ/3 for microspheres. It is a nonresonant phenomenon appearing for a wide range of diameters of the microcylinder or microsphere if the refractive index contrast relative to the background is less than about 2:1. Importantly, inserting within a nanojet a nanoparticle of diameter d(ν) perturbs the far-field backscattered power of the illuminated microsphere by an amount that varies as d(ν)3 for a fixed λ. This perturbation is much slower than the d(ν)6 dependence of Rayleigh scattering for the same nanoparticle, if isolated. This leads to a situation where, for example, the measured far-field backscattered power of a 3-μm diameter microsphere could double if a 30-nm diameter nanoparticle were inserted into the nanojet emerging from the microsphere, despite the nanoparticle having only 1/10,000(th) the cross-section area of the microsphere. In effect, the nanojet serves to project the presence of the nanoparticle to the far field. These properties combine to afford potentially important applications of photonic nanojets for detecting and manipulating nanoscale objects, subdiffraction-resolution nanopatterning and nanolithography, low-loss waveguiding, and ultrahigh-density optical storage.

  14. Photonic Nanojets

    PubMed Central

    Heifetz, Alexander; Kong, Soon-Cheol; Sahakian, Alan V.; Taflove, Allen; Backman, Vadim

    2009-01-01

    This paper reviews the substantial body of literature emerging since 2004 concerning photonic nanojets. The photonic nanojet is a narrow, high-intensity, non-evanescent light beam that can propagate over a distance longer than the wavelength λ after emerging from the shadow-side surface of an illuminated lossless dielectric microcylinder or microsphere of diameter larger than λ. The nanojet’s minimum beamwidth can be smaller than the classical diffraction limit, in fact as small as ~λ/3 for microspheres. It is a nonresonant phenomenon appearing for a wide range of diameters of the microcylinder or microsphere if the refractive index contrast relative to the background is less than about 2:1. Importantly, inserting within a nanojet a nanoparticle of diameter dν perturbs the far-field backscattered power of the illuminated microsphere by an amount that varies as dν3 for a fixed λ. This perturbation is much slower than the dν6 dependence of Rayleigh scattering for the same nanoparticle, if isolated. This leads to a situation where, for example, the measured far-field backscattered power of a 3-μm diameter microsphere could double if a 30-nm diameter nanoparticle were inserted into the nanojet emerging from the microsphere, despite the nanoparticle having only 1/10,000th the cross-section area of the microsphere. In effect, the nanojet serves to project the presence of the nanoparticle to the far field. These properties combine to afford potentially important applications of photonic nanojets for detecting and manipulating nanoscale objects, subdiffraction-resolution nanopatterning and nanolithography, low-loss waveguiding, and ultrahigh-density optical storage. PMID:19946614

  15. Photon Calorimeter

    DOEpatents

    Chow, Tze-Show

    1989-01-01

    A photon calorimeter (20, 40) is provided that comprises a laminar substrate (10, 22, 42) that is uniform in density and homogeneous in atomic composition. A plasma-sprayed coating (28, 48, 52), that is generally uniform in density and homogeneous in atomic composition within the proximity of planes that are parallel to the surfaces of the substrate, is applied to either one or both sides of the laminar substrate. The plasma-sprayed coatings may be very efficiently spectrally tailored in atomic number. Thermocouple measuring junctions (30, 50, 54) are positioned within the plasma-sprayed coatings. The calorimeter is rugged, inexpensive, and equilibrates in temperature very rapidly.

  16. Photon calorimeter

    DOEpatents

    Chow, Tze-Show

    1988-04-22

    A photon calorimeter is provided that comprises a laminar substrate that is uniform in density and homogeneous in atomic composition. A plasma-sprayed coating, that is generally uniform in density and homogeneous in atomic composition within the proximity of planes that are parallel to the surfaces of the substrate, is applied to either one or both sides of the laminar substrate. The plasma-sprayed coatings may be very efficiently spectrally tailored in atomic number. Thermocouple measuring junctions, are positioned within the plasma-sprayed coatings. The calorimeter is rugged, inexpensive, and equilibrates in temperature very rapidly. 4 figs.

  17. Quadrupolar Echo Spectra of the Tunneling CD 3Group

    NASA Astrophysics Data System (ADS)

    Olejniczak, Z.; Detken, A.; Manz, B.; Haeberlen, U.

    Deuteron NMR spectra of both single crystal and powder samples of acetylsalicylic acid-CD 3were measured using the quadrupolar-echo technique. The experiments were done in the temperature range 17-100 K, with a special emphasis on the range 20- 30 K, in which the observable tunneling frequency decreases rapidly from its low-temperature value of 2.7 down to 1.2 MHz. In the tunneling regime, modulations of the line intensities and phases as a function of the echo time τ are observed in the single-crystal spectra. The modulation frequency is equal to the orientation-dependent displacement of the inner satellite pairs (α lines) from the Larmor frequency. These effects were confirmed in numerical simulations and fully explain the phase-modulation effects observed previously in quadrupolar-echo spectra of methyl-deuterated methanol and para-xylene guest molecules in some inclusion compounds. By measuring the temperature and orientation dependence of the quadrupolar lineshapes, it was found that the echo spectra are more sensitive to the value of the tunneling frequency than the spectra obtained from the free induction decay. It is pointed out that, because of the modulation effects, special care must be taken when structural parameters are to be extracted from quadrupolar-echo spectra, in particular from spectra of powder samples.

  18. Light echo detection of circumstellar disks around flaring stars

    NASA Technical Reports Server (NTRS)

    Gaidos, Eric J.

    1994-01-01

    Light echoes can be used to detect and characterize disks around flaring stars. Such disks are thought to be a hallmark of planet formation but are very difficult to detect by ordinary means. Dwarf emission-line M stars experience flares with luminosities comparable to their quiescent photospheres on time scales of minutes, less than the light travel time across a disk many astronomical units in extent; they are thus ideal candidates for such a search. Bromley (1992) calculated that the detection of Jupiter-sized companions using light echoes requires photometric accuracies better than 1 part in 10(exp 6). However, a disk consisting of grains or small bodies will scatter a much larger fraction of the light than a planet of similar mass. I estimate the light echo amplitutdes from plausible geometries of circumstellar material and present simulation light curves. The light echo amplitudes are typically 1% of the flare and I conclude that such events will be detected best in cases where the flare is eclipsed by the star. An examination of the time scales associated with internal processes in a protoplanetary disks around dM stars indicates that any primordial disks may become undetectable in 10(exp 4) years and will have completely disappeared by 10(exp 8) years, the estimated age of dMe stars in the solar neighborhood. However, searches for light echoes might constrain the amount of material continuing to fall into these young stellar systems in the form of comet-like objects.

  19. Modeling of Field-Aligned Guided Echoes in the Plasmasphere

    NASA Technical Reports Server (NTRS)

    Fung, Shing F.; Green, James L.

    2004-01-01

    The conditions under which high frequency (f>>f(sub uh)) long-range extraordinary-mode discrete field-aligned echoes observed by the Radio Plasma Imager (RPI) on board the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite in the plasmasphere are investigated by ray tracing modeling. Field-aligned discrete echoes are most commonly observed by RPI in the plasmasphere although they are also observed over the polar cap region. The plasmasphere field-aligned echoes appearing as multiple echo traces at different virtual ranges are attributed to signals reflected successively between conjugate hemispheres that propagate along or nearly along closed geomagnetic field lines. The ray tracing simulations show that field-aligned ducts with as little as 1% density perturbations (depletions) and less than 10 wavelengths wide can guide nearly field-aligned propagating high frequency X mode waves. Effective guidance of wave at a given frequency and wave normal angle (Psi) depends on the cross-field density scale of the duct, such that ducts with stronger density depletions need to be wider in order to maintain the same gradient of refractive index across the magnetic field. While signal guidance by field aligned density gradient without ducting is possible only over the polar region, conjugate field-aligned echoes that have traversed through the equatorial region are most likely guided by ducting.

  20. Ultrafast NMR diffusion measurements exploiting chirp spin echoes.

    PubMed

    Ahola, Susanna; Mankinen, Otto; Telkki, Ville-Veikko

    2017-04-01

    Standard diffusion NMR measurements require the repetition of the experiment multiple times with varying gradient strength or diffusion delay. This makes the experiment time-consuming and restricts the use of hyperpolarized substances to boost sensitivity. We propose a novel single-scan diffusion experiment, which is based on spatial encoding of two-dimensional data, employing the spin-echoes created by two successive adiabatic frequency-swept chirp π pulses. The experiment is called ultrafast pulsed-field-gradient spin-echo (UF-PGSE). We present a rigorous derivation of the echo amplitude in the UF-PGSE experiment, justifying the theoretical basis of the method. The theory reveals also that the standard analysis of experimental data leads to a diffusion coefficient value overestimated by a few per cent. Although the overestimation is of the order of experimental error and thus insignificant in many practical applications, we propose that it can be compensated by a bipolar gradient version of the experiment, UF-BP-PGSE, or by corresponding stimulated-echo experiment, UF-BP-pulsed-field-gradient stimulated-echo. The latter also removes the effect of uniform background gradients. The experiments offer significant prospects for monitoring fast processes in real time as well as for increasing the sensitivity of experiments by several orders of magnitude by nuclear spin hyperpolarization. Furthermore, they can be applied as basic blocks in various ultrafast multidimensional Laplace NMR experiments. Copyright © 2016 John Wiley & Sons, Ltd.

  1. Classical gluon fields and collective dynamics of color-charge systems

    SciTech Connect

    Voronyuk, V.; Goloviznin, V. V.; Zinovjev, G. M.; Cassing, W.; Molodtsov, S. V.; Snigirev, A. M.; Toneev, V. D.

    2015-03-15

    An investigation of color fields that arise in collisions of relativistic heavy ions reveals that, in the non-Abelian case, a change in the color charge leads to the appearance of an extra term that generates a sizable contribution of color-charge glow in chromoelectric and chromomagnetic fields. The possibility of the appearance of a color echo in the scattering of composite color particles belonging to the dipole type is discussed. Arguments are adduced in support of the statement that such effects are of importance in simulating the first stage of ultrarelativistic heavy-ion collisions,where the initial parton state is determined by a high nonequilibrium parton density and by strong local color fluctuations.

  2. Optical properties of three-dimensional P(St-MAA) photonic crystals on polyester fabrics

    NASA Astrophysics Data System (ADS)

    Liu, Guojin; Zhou, Lan; Wu, Yujiang; Wang, Cuicui; Fan, Qinguo; Shao, Jianzhong

    2015-04-01

    The three-dimensional (3D) photonic crystals with face-centered cubic (fcc) structure was fabricated on polyester fabrics, a kind of soft textile materials quite different from the conventional solid substrates, by gravitational sedimentation self-assembly of monodisperse P(St-MAA) colloidal microspheres. The optical properties of structural colors on polyester fabrics were investigated and the position of photonic band gap was characterized. The results showed that the color-tuning ways of the structural colors from photonic crystals were in accordance with Bragg's law and could be modulated by the size of P(St-MAA) colloidal microspheres and the viewing angles. The L∗a∗b∗ values of the structural colors generated from the assembled polyester fabrics were in agreement with their reflectance spectra. The photonic band gap position of photonic crystals on polyester fabrics could be consistently confirmed by reflectance and transmittance spectra.

  3. Properties of echo spectra observed by MST radars

    NASA Technical Reports Server (NTRS)

    Wakasugi, K.

    1983-01-01

    Turbulent scatter and Fresnel reflection are the fundamental echoing mechanisms to interpret the signals observed by Mesosphere-stratosphere-troposphere (MST) radars. Turbulent scattered echoes provide information about the turbulence structure and mean flow of the atmosphere. Observational results with VHF MST radars, however, show the importance of Fresnel reflection due to the infinite gradient of reflectivity at the edges of a scattering layer. This condition is excluded for the weak fluctuation models but it is still possible to include the observed aspect sensitivity by assuming an anisotropic structure of fluctuations. Another explanation of the aspect sensitivity observed by MST radars is advanced. Spectral estimates by the widely used periodogram were related to a four-dimensional spectrum of atmospheric fluctuations with anisotropic structure. Effects of the radar system such as antenna beam width, beam direction and Fast Fourier Transformations (FFT) data length were discussed for the anisotropic turbulent atmosphere. Echo parameters were also estimated.

  4. Echo 7: Magnetospheric properties determined by artificial electron beams

    SciTech Connect

    Nemzek, R.J.

    1990-01-01

    The sounding rocket Echo 7 was launched from the Poker Flat Research Range. An on-board accelerator injected high-power electron beams into the magnetospheric tail near L = 6.5. After mirroring at the southern conjugate point, about 20 percent of the initial beam electrons returned to the North as Conjugate Echoes, where detectors (scintillators and spectrometers) on four subpayloads measured their energy and bounce time. The other 80 percent of the beam was pitch angle diffused by wave near the equatorial plane either into the conjugate atmosphere or up to mirror points above the payload. Comparison of measured values to calculations showed that the actual magnetosphere during the flight was well-described by the Tsyganenko-Usmanov model magnetosphere with a Kp value of 2- or 2+. Analysis of echo energies yielded values for the highly variable magnetospheric convection electric field.

  5. Geometry of Superluminal Light-Echo Pair Events

    NASA Astrophysics Data System (ADS)

    Nemiroff, Robert J.

    2017-01-01

    Light echoes, shadows, and ionization fronts can and do move faster than light, both in the lab and out in the cosmos. In general, though, a single observer cannot tell the speed of such echoes without distance information -- unless a very specific geometry arises: the radial component crosses c. The observer then sees this crossing location as the site where a pair of bright light echoes is created or annihilated. This pair event tells the observer that a precise speed occurs, a speed that does not scale with distance and so can potentially be leveraged to reveal geometry and distance information. A few simple scattering surface geometries are shown illuminated by a point flash, including linear and circular filaments. In practice, useful astronomical flash sources include novae and supernovae, although in theory any uniquely varying source of stellar variability could be sufficient.

  6. Loschmidt echo in one-dimensional interacting Bose gases

    SciTech Connect

    Lelas, K.; Seva, T.; Buljan, H.

    2011-12-15

    We explore Loschmidt echo in two regimes of one-dimensional interacting Bose gases: the strongly interacting Tonks-Girardeau (TG) regime, and the weakly interacting mean-field regime. We find that the Loschmidt echo of a TG gas decays as a Gaussian when small (random and time independent) perturbations are added to the Hamiltonian. The exponent is proportional to the number of particles and the magnitude of a small perturbation squared. In the mean-field regime the Loschmidt echo shows richer behavior: it decays faster for larger nonlinearity, and the decay becomes more abrupt as the nonlinearity increases; it can be very sensitive to the particular realization of the noise potential, especially for relatively small nonlinearities.

  7. Efficient algorithm for discrimination of overlapping ultrasonic echoes.

    PubMed

    Fortineau, Julien P; Vander Meulen, François; Fortineau, Jérôme; Feuillard, Guy

    2017-01-01

    We propose a method to identify the different echoes of an overlapped ultrasonic signal. This method is based on an iterative algorithm that compares the experimental signal to a realistic dictionary of trial functions and allows identification of one overlapped echo at each iteration. Adding physical parameters to the dictionary such as sample attenuation and ultrasound beam diffraction allows the method to be applied to various materials and sample geometries. Measurements at 500kHz and 5MHz on a ABS material and a copper plate are reported. The effectiveness and the robustness of the method are studied as a function of time delay between the different echoes. We show that taking into account the experimental set-up and material properties in the development of the dictionary are critical to identifying a round-trip signal when overlapping occurs.

  8. Auditory-tactile echo-reverberating stuttering speech corrector

    NASA Astrophysics Data System (ADS)

    Kuniszyk-Jozkowiak, Wieslawa; Adamczyk, Bogdan

    1997-02-01

    The work presents the construction of a device, which transforms speech sounds into acoustical and tactile signals of echo and reverberation. Research has been done on the influence of the echo and reverberation, which are transmitted as acoustic and tactile stimuli, on speech fluency. Introducing the echo or reverberation into the auditory feedback circuit results in a reduction of stuttering. A bit less, but still significant corrective effects are observed while using the tactile channel for transmitting the signals. The use of joined auditory and tactile channels increases the effects of their corrective influence on the stutterers' speech. The results of the experiment justify the use of the tactile channel in the stutterers' therapy.

  9. Light echoes - supernovae 1987A and 1986G

    SciTech Connect

    Schaefer, B.E.

    1987-12-01

    The sudden brilliance of a supernova (SN) eruption will be reflected on surrounding dust grains to create a phantom nebula. The paper presents a series of calculations in which the apparent brightness of this light echo is predicted for a variety of situations where the dust is part of the interstellar medium (ISM). It is found that the supernova 1987 A will have a very bright echo off the ISM that may perhaps be visible with binoculars for many years. At a time of 400 days past maximum, the SN 1986G is found to be 2.7 mag brighter than would be predicted by an extrapolation of its light curve. This unique property has an easy explanation as a light echo off the dust in the dust lane of Cen A. 24 references.

  10. Ecological echoes observed by moving biomimetic sonar characterize objects

    NASA Astrophysics Data System (ADS)

    Kuc, Roman

    2001-05-01

    This paper examines echoes from in situ foliage, similar to those observed by flying bats. A moving sonar converts echoes into spike sequences and applies neural-computational methods to estimate passing range and travel speed. Retro-reflectors and favorably oriented planar patches generate strong echoes (SEs), identified by spike firing rate. Linear sonar trajectories cause SEs to form hyperbolic patterns, termed glints, specified by passing range and travel speed. Passing-range specific detectors compare successive SE times with values in a table and tally coincidences. A glint terminates after a sufficient number of coincidences are tallied and two consecutive mismatches occur in the maximum-count detector. SE arrival jitter necessitates a coincidence window. Short windows identify individual glints while long windows generalize extended objects. SEs from distant objects exhibit almost constant incremental delays, used to estimate sonar travel speed, necessary for robust glint detection. Passing-range estimates may explain how bats can fly through small openings without collision.

  11. Objective color classification of ecstasy tablets by hyperspectral imaging.

    PubMed

    Edelman, Gerda; Lopatka, Martin; Aalders, Maurice

    2013-07-01

    The general procedure followed in the examination of ecstasy tablets for profiling purposes includes a color description, which depends highly on the observers' perception. This study aims to provide objective quantitative color information using visible hyperspectral imaging. Both self-manufactured and illicit tablets, created with different amounts of known colorants were analyzed. We derived reflectance spectra from hyperspectral images of these tablets, and successfully determined the most likely colorant used in the production of all self-manufactured tablets and four of five illicit tablets studied. Upon classification, the concentration of the colorant was estimated using a photon propagation model and a single reference measurement of a tablet of known concentration. The estimated concentrations showed a high correlation with the actual values (R(2) = 0.9374). The achieved color information, combined with other physical and chemical characteristics, can provide a powerful tool for the comparison of tablet seizures, which may reveal their origin.

  12. Structural color change in longhorn beetles Tmesisternus isabellae.

    PubMed

    Liu, F; Dong, B Q; Liu, X H; Zheng, Y M; Zi, J

    2009-08-31

    The elytra of longhorn beetles Tmesisternus isabellae show iridescent golden coloration which stems from long and flat scales imbricated densely on the elytral surface. The scales are able to change coloration from golden in the dry state to red in the wet state with water absorption. Structural characterizations revealed that the iridescent coloration of scales originates from a multilayer in the scale interior. Measurements on both water contact angle and chemical composition indicated that scales are hydrophilic. The change in scale coloration to red in the wet state is due to both the swelling of the multilayer period and water infiltration. The unraveled structural color change and its strategy may not only help us get insight into the biological functionality of structural coloration but also inspire the designs of artificial photonic devices.

  13. Motion Alters Color Appearance

    PubMed Central

    Hong, Sang-Wook; Kang, Min-Suk

    2016-01-01

    Chromatic induction compellingly demonstrates that chromatic context as well as spectral lights reflected from an object determines its color appearance. Here, we show that when one colored object moves around an identical stationary object, the perceived saturation of the stationary object decreases dramatically whereas the saturation of the moving object increases. These color appearance shifts in the opposite directions suggest that normalization induced by the object’s motion may mediate the shift in color appearance. We ruled out other plausible alternatives such as local adaptation, attention, and transient neural responses that could explain the color shift without assuming interaction between color and motion processing. These results demonstrate that the motion of an object affects both its own color appearance and the color appearance of a nearby object, suggesting a tight coupling between color and motion processing. PMID:27824098

  14. Resolution for color photography

    NASA Astrophysics Data System (ADS)

    Hubel, Paul M.; Bautsch, Markus

    2006-02-01

    Although it is well known that luminance resolution is most important, the ability to accurately render colored details, color textures, and colored fabrics cannot be overlooked. This includes the ability to accurately render single-pixel color details as well as avoiding color aliasing. All consumer digital cameras on the market today record in color and the scenes people are photographing are usually color. Yet almost all resolution measurements made on color cameras are done using a black and white target. In this paper we present several methods for measuring and quantifying color resolution. The first method, detailed in a previous publication, uses a slanted-edge target of two colored surfaces in place of the standard black and white edge pattern. The second method employs the standard black and white targets recommended in the ISO standard, but records these onto the camera through colored filters thus giving modulation between black and one particular color component; red, green, and blue color separation filters are used in this study. The third method, conducted at Stiftung Warentest, an independent consumer organization of Germany, uses a whitelight interferometer to generate fringe pattern targets of varying color and spatial frequency.

  15. Echoing and scaling in Einstein-Yang-Mills critical collapse

    NASA Astrophysics Data System (ADS)

    Gundlach, Carsten

    1997-05-01

    We confirm recent numerical results of echoing and mass scaling in the gravitational collapse of a spherical Yang-Mills field by constructing the critical solution and its perturbations as an eigenvalue problem. Because the field equations are not scale invariant, the Yang-Mills critical solution is asymptotically, rather than exactly, self-similar, but the methods for dealing with discrete self-similarity developed for the real scalar field can be generalized. We find an echoing period Δ=0.73784+/-0.00002 and a critical exponent for the black hole mass γ=0.1964+/-0.0007.

  16. Asteroidal meteors detected by MU radar head-echo observations

    NASA Astrophysics Data System (ADS)

    Abe, S.; Kero, J.; Nakamura, T.; Fujiwara, Y.; Kastinen, D.; Watanabe, J.; Hashiguchi, H.

    2016-01-01

    The recent development of the technique carried out using the middle and upper atmosphere radar (MU radar) of Kyoto University at Shigaraki (34.9N, 136.1S), which is large atmospheric VHF radar with 46.5 MHz frequency, 1 MW output transmission power and 8330 m2 aperture array antenna, has established very precise orbital determination from meteor head echoes. A tremendous number, more than 150000, of observed precise orbits of meteoroids by the MU radar meteor head-echo observation will shed light on new discoveries of meteoroids. Here we report some interesting features related with asteroids or distinct comets.

  17. Asteroid shapes from radar echo spectra - A new theoretical approach

    NASA Technical Reports Server (NTRS)

    Ostro, Steven J.; Belkora, Leila; Connelly, Robert

    1988-01-01

    Asteroid shape determinations are presently made by means of a novel technique based on the geometric relation between spectral edge frequencies and the shape of a rotating, rigid radar target. By employing the echo spectra obtained at many rotational phases, the asteroid's convex polar silhouette hull is obtained; noise content is treated as a problem in weighted-least-squares optimization, subject to inequality constraints. The performance of this estimation method is assessed in a series of simulated data giving attention to spectral noise propagation into hull error; sensitivity to echo strength and spectral resolution are also evaluated.

  18. Color dipole cross section and inelastic structure function

    NASA Astrophysics Data System (ADS)

    Jeong, Yu Seon; Kim, C. S.; Luu, Minh Vu; Reno, Mary Hall

    2014-11-01

    Instead of starting from a theoretically motivated form of the color dipole cross section in the dipole picture of deep inelastic scattering, we start with a parametrization of the deep inelastic structure function for electromagnetic scattering with protons, and then extract the color dipole cross section. Using the parametrizations of F 2(ξ = x or W 2 , Q 2) by Donnachie-Landshoff and Block et al., we find the dipole cross section from an approximate form of the presumed dipole cross section convoluted with the perturbative photon wave function for virtual photon splitting into a color dipole with massless quarks. The color dipole cross section determined this way reproduces the original structure function within about 10% for 0 .1 GeV2 ≤ Q 2 ≤10 GeV2. We discuss the dipole cross section at large and small dipole sizes and compare our results with other parametrizations.

  19. Resonance formation in photon-photon collisions

    SciTech Connect

    Gidal, G.

    1988-08-01

    Recent experimental progress on resonance formation in photon-photon collisions is reviewed with particular emphasis on the pseudoscalar and tensor nonents and on the ..gamma gamma..* production of spin-one resonances. 37 refs., 17 figs., 5 tabs.

  20. Physics at high energy photon photon colliders

    SciTech Connect

    Chanowitz, M.S.

    1994-06-01

    I review the physic prospects for high energy photon photon colliders, emphasizing results presented at the LBL Gamma Gamma Collider Workshop. Advantages and difficulties are reported for studies of QCD, the electroweak gauge sector, supersymmetry, and electroweak symmetry breaking.

  1. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, M.; Watson, E.B.; Acocella, J.

    1986-11-04

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10[sup 7] rad, the coloration resistant glass does not lose transparency. 3 figs.

  2. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, Minoru; Watson, E. Bruce; Acocella, John

    1986-01-01

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10.sup.7 rad, the coloration resistant glass does not lose transparency.

  3. Low-light-level EMCCD color camera

    NASA Astrophysics Data System (ADS)

    Heim, Gerald B.; Burkepile, Jon; Frame, Wayne W.

    2006-05-01

    Video cameras have increased in usefulness in military applications over the past four decades. This is a result of many advances in technology and because no one portion of the spectrum reigns supreme under all environmental and operating conditions. The visible portion of the spectrum has the clear advantage of ease of information interpretation, requiring little or no training. This advantage extends into the Near IR (NIR) spectral region to silicon cutoff with little difficulty. Inclusion of the NIR region is of particular importance due to the rich photon content of natural night illumination. The addition of color capability offers another dimension to target/situation discrimination and hence is highly desirable. A military camera must be small, lightweight and low power. Limiting resolution and sensitivity cannot be sacrificed to achieve color capability. Newly developed electron-multiplication CCD sensors (EMCCDs) open the door to a practical low-light/all-light color camera without an image intensifier. Ball Aerospace & Technologies Corp (BATC) has developed a unique color camera that allows the addition of color with a very small impact on low light level performance and negligible impact on limiting resolution. The approach, which includes the NIR portion of the spectrum along with the visible, requires no moving parts and is based on the addition of a sparse sampling color filter to the surface of an EMCCD. It renders the correct hue in a real time, video rate image with negligible latency. Furthermore, camera size and power impact is slight.

  4. Assessing fluorescent color: a review of common practices and their limitations

    NASA Astrophysics Data System (ADS)

    Streitel, Steve

    2003-07-01

    Fluorescent Colorants are widely used around the world to enhance visibility. The outstanding brightness and cleanliness of the colors lend themselves to applications in safety materials, advertising, toys, magazines, packaging, and other areas. The brightness and cleanliness is a result of the colorants ability to reradiate absorbed energy as visible light, usually shorter more energetic photons as longer less energetic photons. This can give reflectance values of well over 100%, sometimes as high as 300%, in the perceived color. A good working definition of fluorescent color is: A colorant that absorbs light energy and reradiates the energy at visible wavelengths. Light that is not absorbed is reflected, as in conventional color. Emission ceases when the excitation energy is removed.

  5. Color Adaptation for Color Deficient Learners.

    ERIC Educational Resources Information Center

    Johnson, Donald D.

    1995-01-01

    Describes a corrective method of color adaptation designed to allow most, if not all, individuals to participate in the learning process as well as social and work-related environments. Provides a concise summation of facts and theories concerning color deficiency. Includes anatomical drawings, graphs, and statistical data. (MJP)

  6. Material design and structural color inspired by biomimetic approach.

    PubMed

    Saito, Akira

    2011-12-01

    Generation of structural color is one of the essential functions realized by living organisms, and its industrial reproduction can result in numerous applications. From this viewpoint, the mechanisms, materials, analytical methods and fabrication technologies of the structural color are reviewed in this paper. In particular, the basic principles of natural photonic materials, the ideas developed from these principles, the directions of applications and practical industrial realizations are presented by summarizing the recent research results.

  7. Material design and structural color inspired by biomimetic approach

    PubMed Central

    Saito, Akira

    2011-01-01

    Generation of structural color is one of the essential functions realized by living organisms, and its industrial reproduction can result in numerous applications. From this viewpoint, the mechanisms, materials, analytical methods and fabrication technologies of the structural color are reviewed in this paper. In particular, the basic principles of natural photonic materials, the ideas developed from these principles, the directions of applications and practical industrial realizations are presented by summarizing the recent research results. PMID:27877459

  8. Color and Streptomycetes1

    PubMed Central

    Pridham, Thomas G.

    1965-01-01

    A report summarizing the results of an international workshop on determination of color of streptomycetes is presented. The results suggest that the color systems which seem most practically appealing and effective to specialists on actinomycetes are those embracing a limited number of color names and groups. The broad groupings allow placement of isolates into reasonably well-defined categories based on color of aerial mycelium. Attempts to expand such systems (more color groups) lead to difficulties. It is common knowledge that many, if not all, of the individual groups would in these broad systems contain strains that differ in many other respects, e.g., spore-wall ornamentation, color of vegetative (substratal) mycelium, morphology of chains of spores, and numerous physiological criteria. Also, cultures of intermediate color can be found, which makes placement difficult. As it now stands, color as a criterion for characterization of streptomycetes and streptoverticillia is in questionable status. Although much useful color information can be obtained by an individual, the application of this information to that in the literature or its use in communication with other individuals leaves much to be desired. More objective methods of color determination are needed. At present, the most effective method that could be used internationally is the color-wheel system of Tresner and Backus. Furthermore, the significance of color in speciation of these organisms is an open question. Obviously, more critical work on the color problem is needed. PMID:14264847

  9. 1. GENERAL VIEW LOOKING NORTH SHOWING 130FOOT SPAN OF ECHO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. GENERAL VIEW LOOKING NORTH SHOWING 130-FOOT SPAN OF ECHO BRIDGE OVER THE CHARLES RIVER. - Sudbury River Aqueduct, Echo Bridge, Spanning Charles River at Upper Newton Falls, Newton, Middlesex County, MA

  10. Unexpected characteristics of the 150 km echoes observed over Gadanki and their implications

    NASA Astrophysics Data System (ADS)

    Patra, A. K.; Pavan Chaitanya, P.

    2016-11-01

    Recent discovery of two distinct types of 150 km echoes, namely, type-A and type-B, and subsequent progress in the large-scale kinetic simulation of photoelectron-induced plasma waves have begun a new era in resolving the five decades long 150 km echoing riddle. In this paper, we present hitherto unrevealed three important and unexpected findings on the two distinct types of 150 km echoes based on Gadanki radar observations. Our observations show unexpected predominance of type-A echoes, strong seasonal dependence of both type-A and type-B echoes, and a surprising connection of the type-B echoes to the unusually deep solar minimum of 2008-2009. We discuss how these results provide important new clues in tethering the competing processes involved in the daytime 150 km echoes and have significance in the recently proposed photoelectron-induced plasma fluctuations as a potential mechanism for the 150 km echoes.

  11. The Trouble with Color.

    ERIC Educational Resources Information Center

    Merchant, David

    1999-01-01

    Discusses problems with color quality in Web sites. Topics include differences in monitor settings, including contrast; amount of video RAM; user preference settings; browser-safe colors; cross-platform readability; and gamma values. (LRW)

  12. Focus on Color Photography

    ERIC Educational Resources Information Center

    Galindez, Peter

    1978-01-01

    Photographs and text describe techniques by which color negative film can be developed and printed. An equipment list, by which black and white printing facilities can be converted to make color prints, is provided. (CP)

  13. Characteristics of spondylotic myelopathy on 3D driven-equilibrium fast spin echo and 2D fast spin echo magnetic resonance imaging: a retrospective cross-sectional study.

    PubMed

    Abdulhadi, Mike A; Perno, Joseph R; Melhem, Elias R; Nucifora, Paolo G P

    2014-01-01

    In patients with spinal stenosis, magnetic resonance imaging of the cervical spine can be improved by using 3D driven-equilibrium fast spin echo sequences to provide a high-resolution assessment of osseous and ligamentous structures. However, it is not yet clear whether 3D driven-equilibrium fast spin echo sequences adequately evaluate the spinal cord itself. As a result, they are generally supplemented by additional 2D fast spin echo sequences, adding time to the examination and potential discomfort to the patient. Here we investigate the hypothesis that in patients with spinal stenosis and spondylotic myelopathy, 3D driven-equilibrium fast spin echo sequences can characterize cord lesions equally well as 2D fast spin echo sequences. We performed a retrospective analysis of 30 adult patients with spondylotic myelopathy who had been examined with both 3D driven-equilibrium fast spin echo sequences and 2D fast spin echo sequences at the same scanning session. The two sequences were inspected separately for each patient, and visible cord lesions were manually traced. We found no significant differences between 3D driven-equilibrium fast spin echo and 2D fast spin echo sequences in the mean number, mean area, or mean transverse dimensions of spondylotic cord lesions. Nevertheless, the mean contrast-to-noise ratio of cord lesions was decreased on 3D driven-equilibrium fast spin echo sequences compared to 2D fast spin echo sequences. These findings suggest that 3D driven-equilibrium fast spin echo sequences do not need supplemental 2D fast spin echo sequences for the diagnosis of spondylotic myelopathy, but they may be less well suited for quantitative signal measurements in the spinal cord.

  14. Frequency selective detection of nuclear quadrupole resonance (NQR) spin echoes

    NASA Astrophysics Data System (ADS)

    Somasundaram, Samuel D.; Jakobsson, Andreas; Smith, John A. S.; Althoefer, Kaspar A.

    2006-05-01

    Nuclear Quadrupole Resonance (NQR) is a radio frequency (RF) technique that can be used to detect the presence of quadrupolar nuclei, such as the 14N nucleus prevalent in many explosives and narcotics. The technique has been hampered by low signal-to-noise ratios and is further aggravated by the presence of RF interference (RFI). To ensure accurate detection, proposed detectors should exploit the rich form of the NQR signal. Furthermore, the detectors should also be robust to any remaining residual interference, left after suitable RFI mitigation has been employed. In this paper, we propose a new NQR data model, particularly for the realistic case where multiple pulse sequences are used to generate trains of spin echoes. Furthermore, we refine two recently proposed approximative maximum likelihood (AML) detectors, enabling the algorithm to optimally exploit the data model of the entire echo train and also incorporate knowledge of the temperature dependent spin-echo decay time. The AML-based detectors ensure accurate detection and robustness against residual RFI, even when the temperature of the sample is not precisely known, by exploiting the dependencies of the NQR resonant lines on temperature. Further robustness against residual interference is gained as the proposed detector is frequency selective; exploiting only those regions of the spectrum where the NQR signal is expected. Extensive numerical evaluations based on both simulated and measured NQR data indicate that the proposed Frequency selective Echo Train AML (FETAML) detector offers a significant improvement as compared to other existing detectors.

  15. Echoing in Autistic Children: A Chronometric Study of Semantic Processing.

    ERIC Educational Resources Information Center

    Shapiro, Theodore; Lucy, Peter

    1978-01-01

    Explores the idea that echoing in autistics differs from normal imitation and represents a different species of production. Subjects were five autistic children, ranging in age from 3 years 10 months to 6 years 8 months, and two normal children, aged 2 years 6 months and 3 years 11 months. (MP)

  16. Echo signal modeling of imaging LADAR target simulator

    NASA Astrophysics Data System (ADS)

    Xu, Rui; Shi, Rui; Wang, Xin; Li, Zhuo

    2014-11-01

    LADAR guidance technology is one of the most promising precision guidance technologies. In the aim of simulating the return waveform of the target, a 3D geometrical model of a target is built and mathematical model of target echo signal for imaging LADAR target simulator is established by using the coordinate transformation, radar equation and ranging equation. First, the 3D geometrical data of the object model is obtained by 3D geometrical modeling. Then, target coordinate system and viewpoint coordinate system are created respectively. 3D geometrical model is built in the target coordinate system. The 3D geometrical model is transformed to the viewpoint coordinate system based on the derived relationship between the two coordinate systems. Furthermore, the range information of the target could be obtained under viewpoint coordinate system. Thus, the data of the target echo signal can be obtained by using radar equation and ranging equation. Finally, the echo signal can be exported through corresponding data interface. In order to validate the method proposed in this paper, the echo signal generated by a typical target is computed and compared with the theory solutions. The signals can be applied to drive target simulator to generate a physical target LADAR image.

  17. Echo Behavior in Large Populations of Chemical Oscillators

    NASA Astrophysics Data System (ADS)

    Chen, Tianran; Tinsley, Mark R.; Ott, Edward; Showalter, Kenneth

    2016-10-01

    Experimental and theoretical studies are reported, for the first time, on the observation and characterization of echo phenomena in oscillatory chemical reactions. Populations of uncoupled and coupled oscillators are globally perturbed. The macroscopic response to this perturbation dies out with time: At some time τ after the perturbation (where τ is long enough that the response has died out), the system is again perturbed, and the initial response to this second perturbation again dies out. Echoes can potentially appear as responses that arise at 2 τ ,3 τ ,... after the first perturbation. The phase-resetting character of the chemical oscillators allows a detailed analysis, offering insights into the origin of the echo in terms of an intricate structure of phase relationships. Groups of oscillators experiencing different perturbations are analyzed with a geometric approach and in an analytical theory. The characterization of echo phenomena in populations of chemical oscillators reinforces recent theoretical studies of the behavior in populations of phase oscillators [E. Ott et al., Chaos 18, 037115 (2008)]. This indicates the generality of the behavior, including its likely occurrence in biological systems.

  18. MU Radar Head Echo Observations of the 2011 October Draconids

    NASA Astrophysics Data System (ADS)

    Kero, J.; Fujiwara, Y.; Abo, M.; Szasz, C.; Nakamura, T.

    2012-05-01

    13 meteor head echoes from the 2011 October Draconids were observed with the MU radar in Japan. Their weighted mean geocentric velocity was 20.6±0.4km/s and the radiant located at RA=263°.3±0°.6, dec=55°.8±0°.2, in good agreement with simulations.

  19. Larry Echo Hawk: A Rising Star from Idaho.

    ERIC Educational Resources Information Center

    Wisecarver, Charmaine

    1993-01-01

    Larry Echo Hawk, Idaho attorney general and former state legislator, discusses success factors in college and law school; early experiences as an Indian lawyer; first election campaign; and his views on tribal sovereignty, state-tribal relationship, gambling, and his dual responsibility to the general public and Native American issues. (SV)

  20. HF Radar Sea-echo from Shallow Water.

    PubMed

    Lipa, Belinda; Nyden, Bruce; Barrick, Don; Kohut, Josh

    2008-08-06

    HF radar systems are widely and routinely used for the measurement of ocean surface currents and waves. Analysis methods presently in use are based on the assumption of infinite water depth, and may therefore be inadequate close to shore where the radar echo is strongest. In this paper, we treat the situation when the radar echo is returned from ocean waves that interact with the ocean floor. Simulations are described which demonstrate the effect of shallow water on radar sea-echo. These are used to investigate limits on the existing theory and to define water depths at which shallow-water effects become significant. The second-order spectral energy increases relative to the first-order as the water depth decreases, resulting in spectral saturation when the waveheight exceeds a limit defined by the radar transmit frequency. This effect is particularly marked for lower radar transmit frequencies. The saturation limit on waveheight is less for shallow water. Shallow water affects second-order spectra (which gives wave information) far more than first-order (which gives information on current velocities), the latter being significantly affected only for the lowest radar transmit frequencies for extremely shallow water. We describe analysis of radar echo from shallow water measured by a Rutgers University HF radar system to give ocean wave spectral estimates. Radar-derived wave height, period and direction are compared with simultaneous shallow-water in-situ measurements.

  1. Project Echo: Horn-Reflector Antenna for Space Communication

    NASA Technical Reports Server (NTRS)

    Crawford, A. B.; Hogg, D. C.; Hunt, L. E.

    1961-01-01

    This paper describes the mechanical features of the horn- reflector antenna used for receiving signals reflected from the Project Echo balloon satellite, and presents in some detail the electrical characteristics (radiation patterns and gain) measured at a frequency of 2390 Mc. Theoretically derived characteristics which agree very well with the measurements are also presented; details of the calculations are given in the appendices.

  2. Communication: Phase incremented echo train acquisition in NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Baltisberger, Jay H.; Walder, Brennan J.; Keeler, Eric G.; Kaseman, Derrick C.; Sanders, Kevin J.; Grandinetti, Philip J.

    2012-06-01

    We present an improved and general approach for implementing echo train acquisition (ETA) in magnetic resonance spectroscopy, particularly where the conventional approach of Carr-Purcell-Meiboom-Gill (CPMG) acquisition would produce numerous artifacts. Generally, adding ETA to any N-dimensional experiment creates an N + 1 dimensional experiment, with an additional dimension associated with the echo count, n, or an evolution time that is an integer multiple of the spacing between echo maxima. Here we present a modified approach, called phase incremented echo train acquisition (PIETA), where the phase of the mixing pulse and every other refocusing pulse, ϕP, is incremented as a single variable, creating an additional phase dimension in what becomes an N + 2 dimensional experiment. A Fourier transform with respect to the PIETA phase, ϕP, converts the ϕP dimension into a Δp dimension where desired signals can be easily separated from undesired coherence transfer pathway signals, thereby avoiding cumbersome or intractable phase cycling schemes where the receiver phase must follow a master equation. This simple modification eliminates numerous artifacts present in NMR experiments employing CPMG acquisition and allows "single-scan" measurements of transverse relaxation and J-couplings. Additionally, unlike CPMG, we show how PIETA can be appended to experiments with phase modulated signals after the mixing pulse.

  3. Scheduling the EChO survey with known exoplanets

    NASA Astrophysics Data System (ADS)

    Morales, J. C.; Beaulieu, J.-P.; Coudé du Foresto, V.; Ollivier, M.; Castello, I. Ortega; Clédassou, R.; Jaubert, J.; Van-Troostenberghe, P.; Varley, R.; Waldmann, I. P.; Pascale, E.; Tessenyi, M.

    2015-12-01

    The Exoplanet Characterization Observatory ( EChO) is a concept of a dedicated space telescope optimized for low-resolution transit and occultation spectroscopy to study the exoplanet diversity through the composition of their atmospheres. The scope of this paper is to answer the following question: Can we schedule a nominal EChO mission, with targets known today (in mid 2013), given the science requirements, realistic performances and operational constraints? We examine this issue from the point of view of duration of the mission and the scheduling restrictions with a sample of exoplanet systems known nowadays. We choose different scheduling algorithms taking into account the science and operational constraints and we verified that it is fairly straightforward to schedule a mission scenario over the lifetime of EChO compliant with the science requirements. We identified agility as a critical constraint that reduces significantly the efficiency of the survey. We conclude that even with known targets today the EChO science objectives can be reached in the 4.5 years duration of the mission. We also show that it is possible to use gaps between exoplanet observations, to fit the required calibration observations, data downlinks and station keeping operations or even to observe more exoplanet targets to be discovered in the coming years.

  4. Participatory Culture at the Echo Park Film Center

    ERIC Educational Resources Information Center

    Rosales, Jennifer Ann

    2013-01-01

    The Echo Park Film Center, a Los Angeles nonprofit media education organization, teaches underprivileged youth how to comprehend and make media in order to empower them to speak and be heard. Due to the organization's nonmainstream media courses and its connection to its community, the Center is able to create a participatory and socially…

  5. Long-term changes of (polar) mesosphere summer echoes

    NASA Astrophysics Data System (ADS)

    Bremer, J.; Hoffmann, P.; Latteck, R.; Singer, W.; Zecha, M.

    2009-10-01

    Strong VHF radar echoes have been observed not only during summer months at polar latitudes (polar mesosphere summer echoes, PMSE) but also at middle latitudes (mesosphere summer echoes, MSE). These echoes are closely connected with small ice particles, thus containing information about mesospheric temperature and water vapour content. But the (P)MSE also depend on the ionisation due to solar wave radiation and precipitating high energetic particles. Observations with VHF radars at Andenes (69.3°N; 16.0°E) since 1994 and at Kühlungsborn (54.6°N; 11.8°E) since 1998 are used for investigations of the solar and geomagnetic control of the (P)MSE as well as of possible long-term changes. The (P)MSE are positively correlated with the solar Lyman [alpha] radiation and the geomagnetic activity and have slightly positive trends. Due to the limited measuring period, the significance levels of the detected (P)MSE trends are small. Positive trends in noctilucent clouds (NLC) and polar mesospheric clouds (PMC) are in general agreement with (P)MSE trends.

  6. Color rendition engine.

    PubMed

    Zukauskas, Artūras; Vaicekauskas, Rimantas; Vitta, Pranciškus; Tuzikas, Arūnas; Petrulis, Andrius; Shur, Michael

    2012-02-27

    A source of white light with continuously tuned color rendition properties, such as color fidelity, as well as color saturating and color dulling ability has been developed. The source, which is composed of red (R), amber (A), green (G), and blue (B) light-emitting diodes, has a spectral power distribution varied as a weighted sum of "white" RGB and AGB blends. At the RGB and AGB end-points, the source has a highest color saturating and color dulling ability, respectively, as follows from the statistical analysis of the color-shift vectors for 1269 Munsell samples. The variation of the weight parameter allows for continuously traversing all possible metameric RAGB blends, including that with the highest color fidelity. The source was used in a psychophysical experiment on the estimation of the color appearance of familiar objects, such as vegetables, fruits, and soft-drink cans of common brands, at correlated color temperatures of 3000 K, 4500 K, and 6500 K. By continuously tuning the weight parameter, each of 100 subjects selected RAGB blends that, to their opinion, matched lighting characterized as "most saturating," "most dulling," "most natural," and "preferential". The end-point RGB and AGB blends have been almost unambiguously attributed to "most saturating" and "most dulling" lighting, respectively. RAGB blends that render a highest number of colors with high fidelity have, on average, been attributed to "most natural" lighting. The "preferential" color quality of lighting has, on average, been matched to RAGB blends that provide color rendition with fidelity somewhat reduced in favor of a higher saturation. Our results infer that tunable "color rendition engines" can validate color rendition metrics and provide lighting meeting specific needs and preferences to color quality.

  7. Mysterious coloring: structural origin of color mixing for two breeds of Papilio butterflies.

    PubMed

    Diao, Ying-Ying; Liu, Xiang-Yang

    2011-05-09

    The structural origin of the coloration mechanisms and related extraordinary optical properties of the wing scales of two breeds of Papilio butterflies, namely, Papilio ulysses and Papilio blumei, are explored. The precise ordered biophotonic nanostructures of the wing scales are characterized by scanning electron microscopy (SEM). Despite their structural similarities, the two breeds of Papilio butterflies do not exhibit any analogy in their optical performances. When illuminated with UV-Vis light, P. ulysses gives rise to two reflection peaks: one is from concavities, and the other is from ridges. These two spectral peaks shift their positions under different illumination angles (normal and 45° incident light). In contrast, the spectra for the green scales of P. blumei give one broad reflection peak, and the peak remains the same under normal and 45° incident light. The optical microscopy images indicate that the cap-shaped concavities on P. blumei's wing scales generate an abnormal bicolor reflection with a strong polarization effect. Both of these two breeds of butterflies take advantage of color mixing strategy: the blue color of P. ulysses is mixed by the colors reflected from concavities and ridges; the green color of P. blumei is produced by the biocolor reflection from concavities. The differences of their coloration mixing mechanisms and optical performances are due to the variations of their nanostructures. The investigation of the color mixing mechanisms of these biologically photonic nanostructures may offer a convenient way for fabricating optical devices based on biomimicry.

  8. Optomechanical photon shuttling between photonic cavities.

    PubMed

    Li, Huan; Li, Mo

    2014-11-01

    Mechanical motion of photonic devices driven by optical forces provides a profound means of coupling between optical fields. The current focus of these optomechanical effects has been on cavity optomechanics systems in which co-localized optical and mechanical modes interact strongly to enable wave mixing between photons and phonons, and backaction cooling of mechanical modes. Alternatively, extended mechanical modes can also induce strong non-local effects on propagating optical fields or multiple localized optical modes at distances. Here, we demonstrate a multicavity optomechanical device in which torsional optomechanical motion can shuttle photons between two photonic crystal nanocavities. The resonance frequencies of the two cavities, one on each side of this 'photon see-saw', are modulated antisymmetrically by the device's rotation. Pumping photons into one cavity excites optomechanical self-oscillation, which strongly modulates the inter-cavity coupling and shuttles photons to the other empty cavity during every oscillation cycle in a well-regulated fashion.

  9. Reimagining the Color Wheel

    ERIC Educational Resources Information Center

    Snyder, Jennifer

    2011-01-01

    Color wheels are a traditional project for many teachers. The author has used them in art appreciation classes for many years, but one problem she found when her pre-service art education students created colored wheels was that they were boring: simple circles, with pie-shaped pieces, which students either painted or colored in. This article…

  10. Color: Implications in dentistry

    PubMed Central

    Sikri, Vimal K

    2010-01-01

    The success of restorative dentistry is determined on the basis of functional and esthetic results. To achieve esthetics, four basic determinants are required in sequence; viz., position, contour, texture and color. The knowledge of the concept of color is essential for achieving good esthetics. This review compiles the various aspects of color, its measurements and shade matching in dentistry. PMID:21217954

  11. Biology of Skin Color.

    ERIC Educational Resources Information Center

    Corcos, Alain

    1983-01-01

    Information from scientific journals on the biology of skin color is discussed. Major areas addressed include: (1) biology of melanin, melanocytes, and melanosomes; (2) melanosome and human diversity; (3) genetics of skin color; and (4) skin color, geography, and natural selection. (JN)

  12. Color vision deficiencies

    NASA Astrophysics Data System (ADS)

    Vannorren, D.

    1982-04-01

    Congenital and acquired color vision defects are described in the context of physiological data. Light sources, photometry, color systems and test methods are described. A list of medicines is also presented. The practical social consequences of color vision deficiencies are discussed.

  13. Color Television in Instruction.

    ERIC Educational Resources Information Center

    Bretz, Rudy

    In spite of repeated research into the matter, no evidence has been discovered to support the claim that color television is superior to black-and-white television as an instructional aid. It is possible that there are advantages to color television which are unmeasured or unmeasurable, but the current claims for color; that it heightens realism,…

  14. Color Discrimination Work Sample.

    ERIC Educational Resources Information Center

    Shawsheen Valley Regional Vocational-Technical High School, Billerica, MA.

    This manual contains a work sample intended to assess a handicapped student's ability to see likenesses or differences in colors or shades, identifying or matching certain colors, and selecting colors that go together. Section 1 describes the assessment and lists related occupations and DOT codes. Instructions to the evaluator are provided in the…

  15. A Year in the Life of an Infrared Echo

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Figure 1: Supernova Remnant Cassiopeia A One Year Apart

    These Spitzer Space Telescope images, taken one year apart, show the supernova remnant Cassiopeia A (yellow ball) and surrounding clouds of dust (reddish orange). The pictures illustrate that a blast of light from Cassiopeia A is waltzing outward through the dusty skies. This dance, called an 'infrared echo,' began when the remnant erupted about 50 years ago.

    Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion 325 years ago. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died. This remnant is located 10,000 light-years away in the northern constellation Cassiopeia.

    Infrared echoes are created when a star explodes or erupts, flashing light into surrounding clumps of dust. As the light zips through the dust clumps, it heats them up, causing them to glow successively in infrared, like a chain of Christmas bulbs lighting up one by one. The result is an optical illusion, in which the dust appears to be flying outward at the speed of light. Echoes are distinct from supernova shockwaves, which are made up material that is swept up and hurled outward by exploding stars.

    This infrared echo is the largest ever seen, stretching more than 50 light-years away from Cassiopeia A. If viewed from Earth, the entire movie frame would take up the same amount of space as two full moons.

    Hints of an older infrared echo from Cassiopeia A's supernova explosion hundreds of years ago can also be seen.

    The top Spitzer image was taken on November 30, 2003, and the bottom, on December 2, 2004.

  16. Neutron resonance spin echo with longitudinal DC fields

    NASA Astrophysics Data System (ADS)

    Krautloher, Maximilian; Kindervater, Jonas; Keller, Thomas; Häußler, Wolfgang

    2016-12-01

    We report on the design, construction, and performance of a neutron resonance spin echo (NRSE) instrument employing radio frequency (RF) spin flippers combining RF fields with DC fields, the latter oriented parallel (longitudinal) to the neutron propagation direction (longitudinal NRSE (LNRSE)). The advantage of the longitudinal configuration is the inherent homogeneity of the effective magnetic path integrals. In the center of the RF coils, the sign of the spin precession phase is inverted by a π flip of the neutron spins, such that non-uniform spin precession at the boundaries of the RF flippers is canceled. The residual inhomogeneity can be reduced by Fresnel- or Pythagoras-coils as in the case of conventional spin echo instruments (neutron spin echo (NSE)). Due to the good intrinsic homogeneity of the B0 coils, the current densities required for the correction coils are at least a factor of three less than in conventional NSE. As the precision and the current density of the correction coils are the limiting factors for the resolution of both NSE and LNRSE, the latter has the intrinsic potential to surpass the energy resolution of present NSE instruments. Our prototype LNRSE spectrometer described here was implemented at the resonance spin echo for diverse applications (RESEDA) beamline at the MLZ in Garching, Germany. The DC fields are generated by B0 coils, based on resistive split-pair solenoids with an active shielding for low stray fields along the beam path. One pair of RF flippers at a distance of 2 m generates a field integral of ˜0.5 Tm. The LNRSE technique is a future alternative for high-resolution spectroscopy of quasi-elastic excitations. In addition, it also incorporates the MIEZE technique, which allows to achieve spin echo resolution for spin depolarizing samples and sample environments. Here we present the results of numerical optimization of the coil geometry and first data from the prototype instrument.

  17. Neutron resonance spin echo with longitudinal DC fields.

    PubMed

    Krautloher, Maximilian; Kindervater, Jonas; Keller, Thomas; Häußler, Wolfgang

    2016-12-01

    We report on the design, construction, and performance of a neutron resonance spin echo (NRSE) instrument employing radio frequency (RF) spin flippers combining RF fields with DC fields, the latter oriented parallel (longitudinal) to the neutron propagation direction (longitudinal NRSE (LNRSE)). The advantage of the longitudinal configuration is the inherent homogeneity of the effective magnetic path integrals. In the center of the RF coils, the sign of the spin precession phase is inverted by a π flip of the neutron spins, such that non-uniform spin precession at the boundaries of the RF flippers is canceled. The residual inhomogeneity can be reduced by Fresnel- or Pythagoras-coils as in the case of conventional spin echo instruments (neutron spin echo (NSE)). Due to the good intrinsic homogeneity of the B0 coils, the current densities required for the correction coils are at least a factor of three less than in conventional NSE. As the precision and the current density of the correction coils are the limiting factors for the resolution of both NSE and LNRSE, the latter has the intrinsic potential to surpass the energy resolution of present NSE instruments. Our prototype LNRSE spectrometer described here was implemented at the resonance spin echo for diverse applications (RESEDA) beamline at the MLZ in Garching, Germany. The DC fields are generated by B0 coils, based on resistive split-pair solenoids with an active shielding for low stray fields along the beam path. One pair of RF flippers at a distance of 2 m generates a field integral of ∼0.5 Tm. The LNRSE technique is a future alternative for high-resolution spectroscopy of quasi-elastic excitations. In addition, it also incorporates the MIEZE technique, which allows to achieve spin echo resolution for spin depolarizing samples and sample environments. Here we present the results of numerical optimization of the coil geometry and first data from the prototype instrument.

  18. Clutter interference and the integration time of echoes in the echolocating bat, Eptesicus fuscus.

    PubMed

    Simmons, J A; Freedman, E G; Stevenson, S B; Chen, L; Wohlgenant, T J

    1989-10-01

    The ability of the echolocating bat, Eptesicus fuscus, to detect a sonar target is affected by the presence of other targets along the same axis at slightly different ranges. If echoes from one target arrive at about the same delay as echoes from another target, clutter interference occurs and one set of echoes masks the other. Although the bat's sonar emissions and the echoes themselves are 2 to 5 ms long, echoes (of approximately equal sensation levels--around 15 dB SL) only interfere with each other if they arrive within 200 to 400 microseconds of the same arrival time. This figure is an estimate of the integration time of the bat's sonar receiver for echoes. The fine structure of the clutter-interference data reflects the reinforcement and cancellation of echoes according to their time separation. When clutter interference first occurs, the waveforms of test and cluttering echoes already overlap for much of their duration. The masking effect underlying clutter interference appears specifically due to overlap, not between raw echo waveforms, but between the patterns of mechanical excitation created when echoes pass through bandpass filters equivalent to auditory-nerve tuning curves. While the time scale of clutter interference is substantially shorter than the duration of echo waveforms, it still is much longer than the eventual width of a target's range-axis image expressed in terms of echo delay.

  19. 32 CFR 199.5 - TRICARE Extended Care Health Option (ECHO).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... disabling effects of the ECHO-eligible dependent's qualifying condition. Services include those necessary to.... The cumulative effect of multiple disabilities, as determined by the Director, TRICARE Management... involving separate body systems. (3) Loss of ECHO eligibility. Eligibility for ECHO benefits ceases as of...

  20. Echo-acoustic flow shapes object representation in spatially complex acoustic scenes.

    PubMed

    Greiter, Wolfgang; Firzlaff, Uwe

    2017-03-08

    Echolocating bats use echoes of their sonar emissions to determine the position and distance of objects or prey. Target distance is represented as a map of echo delay in the auditory cortex (AC) of bats. During a bat's flight through a natural complex environment, echo streams are reflected from multiple objects along its flight path. Separating such complex streams of echoes or other sounds is a challenge for the auditory system of bats as well as other animals. We investigated the representation of multiple echo streams in the AC of anaesthetized bats (Phyllostomus discolor) and tested the hypothesis, if neurons can lock on echoes from specific objects in a complex echo-acoustic pattern while the representation of surrounding objects is suppressed. We combined naturalistic pulse/echo sequences simulating a bat's flight through a virtual acoustic space with extracellular recordings. Neurons could selectively lock on echoes from one object in complex echo streams originating from two different objects along a virtual flight path. The objects were processed sequentially in the order in which they were approached. Object selection depended on sequential changes of echo delay and amplitude but not on absolute values. Furthermore, the detailed representation of the object echo delays in the cortical target range map was not fixed but could be dynamically adapted depending on the temporal pattern of sonar emission during target approach within a simulated flight sequence.

  1. Modeling Statistics of Fish Patchiness and Predicting Associated Influence on Statistics of Acoustic Echoes

    DTIC Science & Technology

    2015-09-30

    active sonar. Toward this goal, fundamental advances in the understanding of fish behavior , especially in aggregations, will be made under conditions...relevant to the echo statistics problem. OBJECTIVES To develop new models of behavior of fish aggregations, including the fission/fusion process...and to describe the echo statistics associated with the random fish behavior using existing formulations of echo statistics. APPROACH

  2. Project ECHO: Electronic Communications from Halo Orbit

    NASA Technical Reports Server (NTRS)

    Borrelli, Jason; Cooley, Bryan; Debole, Marcy; Hrivnak, Lance; Nielsen, Kenneth; Sangmeister, Gary; Wolfe, Matthew

    1994-01-01

    The design of a communications relay to provide constant access between the Earth and the far side of the Moon is presented. Placement of the relay in a halo orbit about the L2 Earth-Moon Lagrange point allows the satellite to maintain constant simultaneous communication between Earth and scientific payloads on the far side of the Moon. The requirements of NASA's Discovery-class missions adopted and modified for this design are: total project cost should not exceed $150 million excluding launch costs, launch must be provided by Delta-class vehicle, and the satellite should maintain an operational lifetime of 10 to 15 years. The spacecraft will follow a transfer trajectory to the L2 point, after launch by a Delta II 7925 vehicle in 1999. Low-level thrust is used for injection into a stationkeeping-free halo orbit once the spacecraft reaches the L2 point. The shape of this halo orbit is highly elliptical with the maximum excursion from the L2 point being 35000 km. A spun section and despun section connected through a bearing and power transfer assembly (BAPTA) compose the structure of the spacecraft. Communications equipment is placed on the despun section to provide for a stationary dual parabolic offset-feed array antenna system. The dual system is necessary to provide communications coverage during portions of maximum excursion on the halo orbit. Transmissions to the NASA Deep Space Network 34 m antenna include six channels (color video, two voice, scientific data from lunar payloads, satellite housekeeping and telemetry and uplinked commands) using the S- and X-bands. Four radioisotope thermoelectric generators (RTG's) provide a total of 1360 W to power onboard systems and any two of the four Hughes 13 cm ion thrusters at once. Output of the ion thrusters is approximately 17.8 mN each with xenon as the propellant. Presence of torques generated by solar pressure on the antenna dish require the addition of a 'skirt' extending from the spun section of the satellite

  3. Slice Accelerated Gradient-Echo Spin-Echo Dynamic Susceptibility Contrast Imaging with Blipped CAIPI for Increased Slice Coverage

    PubMed Central

    Eichner, Cornelius; Jafari-Khouzani, Kourosh; Cauley, Stephen; Bhat, Himanshu; Polaskova, Pavlina; Andronesi, Ovidiu C.; Rapalino, Otto; Turner, Robert; Wald, Lawrence L.; Stufflebeam, Steven; Setsompop, Kawin

    2014-01-01

    Purpose To improve slice coverage of gradient echo spin echo (GESE) sequences for dynamic susceptibility contrast (DSC) MRI using a simultaneous-multiple-slice (SMS) method. Methods Data were acquired on 3 Tesla (T) MR scanners with a 32-channel head coil. To evaluate use of SMS for DSC, an SMS GESE sequence with two-fold slice coverage and same temporal sampling was compared with a standard GESE sequence, both with 2× in-plane acceleration. A signal to noise ratio (SNR) comparison was performed on one healthy subject. Additionally, data with Gadolinium injection were collected on three patients with glioblastoma using both sequences, and perfusion analysis was performed on healthy tissues as well as on tumor. Results Retained SNR of SMS DSC is 90% for a gradient echo (GE) and 99% for a spin echo (SE) acquisition, compared with a standard acquisition without slice acceleration. Comparing cerebral blood volume maps, it was observed that the results of standard and SMS acquisitions are comparable for both GE and SE images. Conclusion Two-fold slice accelerated DSC MRI achieves similar SNR and perfusion metrics as a standard acquisition, while allowing a significant increase in slice coverage of the brain. The results also point to a possibility to improve temporal sampling rate, while retaining the same slice coverage. PMID:24285593

  4. Proton echo-planar spectroscopic imaging with highly effective outer volume suppression using combined presaturation and spatially selective echo dephasing.

    PubMed

    Chu, Archie; Alger, Jeffry R; Moore, Gregory J; Posse, Stefan

    2003-05-01

    A highly effective outer volume suppression (OVS) technique, termed spatially selective echo dephasing (SSED), which employs gradient dephasing of spatially selective spin echoes, is introduced. SSED, which is relatively insensitive to T(1) dispersion among lipid signals and B(1) inhomogeneity, was integrated with very high spatial resolution 2D proton echo-planar spectroscopic imaging (PEPSI) to assess residual lipid bleeding into cortical regions in the human brain. The method was optimized to minimize signal refocusing of secondary spin-echoes in areas of overlapping suppression slices. A comparison of spatial presaturation with single or double SSED, and with combined presaturation and SSED shows that the latter method has superior performance with spatially uniform lipid suppression factors in excess of 70. Metabolite mapping (choline, creatine, and NAA) with a 64 x 64 spatial matrix and 0.3 cm(3) voxels in close proximity to peripheral lipid regions was demonstrated at 1.5 T with a scan time of 32 min using the standard head coil.

  5. Accelerated Fast Spin-Echo Magnetic Resonance Imaging of the Heart Using a Self-Calibrated Split-Echo Approach

    PubMed Central

    Klix, Sabrina; Hezel, Fabian; Fuchs, Katharina; Ruff, Jan; Dieringer, Matthias A.; Niendorf, Thoralf

    2014-01-01

    Purpose Design, validation and application of an accelerated fast spin-echo (FSE) variant that uses a split-echo approach for self-calibrated parallel imaging. Methods For self-calibrated, split-echo FSE (SCSE-FSE), extra displacement gradients were incorporated into FSE to decompose odd and even echo groups which were independently phase encoded to derive coil sensitivity maps, and to generate undersampled data (reduction factor up to R = 3). Reference and undersampled data were acquired simultaneously. SENSE reconstruction was employed. Results The feasibility of SCSE-FSE was demonstrated in phantom studies. Point spread function performance of SCSE-FSE was found to be competitive with traditional FSE variants. The immunity of SCSE-FSE for motion induced mis-registration between reference and undersampled data was shown using a dynamic left ventricular model and cardiac imaging. The applicability of black blood prepared SCSE-FSE for cardiac imaging was demonstrated in healthy volunteers including accelerated multi-slice per breath-hold imaging and accelerated high spatial resolution imaging. Conclusion SCSE-FSE obviates the need of external reference scans for SENSE reconstructed parallel imaging with FSE. SCSE-FSE reduces the risk for mis-registration between reference scans and accelerated acquisitions. SCSE-FSE is feasible for imaging of the heart and of large cardiac vessels but also meets the needs of brain, abdominal and liver imaging. PMID:24728341

  6. Color Classification of Coordination Compounds.

    ERIC Educational Resources Information Center

    Poncini, Laurence; Wimmer, Franz L.

    1987-01-01

    Proposes that colored compounds be classified by reference to a standard color-order system incorporating a color dictionary. Argues that the colors of new compounds could be incorporated into the characterization process and into computer storage systems. (TW)

  7. Watermarking spot colors

    NASA Astrophysics Data System (ADS)

    Alattar, Osama M.; Reed, Alastair M.

    2003-06-01

    Watermarking of printed materials has usually focused on process inks of cyan, magenta, yellow and black (CMYK). In packaging, almost three out of four printed materials include spot colors. Spot colors are special premixed inks, which can be produced in a vibrant range of colors, often outside the CMYK color gamut. In embedding a watermark into printed material, a common approach is to modify the luminance value of each pixel in the image. In the case of process color work pieces, the luminance change can be scaled to the C, M, Y and K channels using a weighting function, to produce the desired change in luminance. In the case of spot color art designs, there is only one channel available and the luminance change is applied to this channel. In this paper we develop a weighting function to embed the watermark signal across the range of different spot colors. This weighting function normalizes visibility effect and signal robustness across a wide range of different spot colors. It normalizes the signal robustness level over the range of an individual spot color"s intensity levels. Further, it takes into account the sensitivity of the capturing device to the different spot colors.

  8. True Colors Shining Through

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image mosaic illustrates how scientists use the color calibration targets (upper left) located on both Mars Exploration Rovers to fine-tune the rovers' sense of color. In the center, spectra, or light signatures, acquired in the laboratory of the colored chips on the targets are shown as lines. Actual data from Mars Exploration Rover Spirit's panoramic camera is mapped on top of these lines as dots. The plot demonstrates that the observed colors of Mars match the colors of the chips, and thus approximate the red planet's true colors. This finding is further corroborated by the picture taken on Mars of the calibration target, which shows the colored chips as they would appear on Earth.

  9. Acquired color vision deficiency.

    PubMed

    Simunovic, Matthew P

    2016-01-01

    Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.

  10. Spherical colloidal photonic crystals.

    PubMed

    Zhao, Yuanjin; Shang, Luoran; Cheng, Yao; Gu, Zhongze

    2014-12-16

    CONSPECTUS: Colloidal photonic crystals (PhCs), periodically arranged monodisperse nanoparticles, have emerged as one of the most promising materials for light manipulation because of their photonic band gaps (PBGs), which affect photons in a manner similar to the effect of semiconductor energy band gaps on electrons. The PBGs arise due to the periodic modulation of the refractive index between the building nanoparticles and the surrounding medium in space with subwavelength period. This leads to light with certain wavelengths or frequencies located in the PBG being prohibited from propagating. Because of this special property, the fabrication and application of colloidal PhCs have attracted increasing interest from researchers. The most simple and economical method for fabrication of colloidal PhCs is the bottom-up approach of nanoparticle self-assembly. Common colloidal PhCs from this approach in nature are gem opals, which are made from the ordered assembly and deposition of spherical silica nanoparticles after years of siliceous sedimentation and compression. Besides naturally occurring opals, a variety of manmade colloidal PhCs with thin film or bulk morphology have also been developed. In principle, because of the effect of Bragg diffraction, these PhC materials show different structural colors when observed from different angles, resulting in brilliant colors and important applications. However, this angle dependence is disadvantageous for the construction of some optical materials and devices in which wide viewing angles are desired. Recently, a series of colloidal PhC materials with spherical macroscopic morphology have been created. Because of their spherical symmetry, the PBGs of spherical colloidal PhCs are independent of rotation under illumination of the surface at a fixed incident angle of the light, broadening the perspective of their applications. Based on droplet templates containing colloidal nanoparticles, these spherical colloidal PhCs can be

  11. All-Dielectric Colored Metasurfaces with Silicon Mie Resonators.

    PubMed

    Proust, Julien; Bedu, Frédéric; Gallas, Bruno; Ozerov, Igor; Bonod, Nicolas

    2016-08-23

    The photonic resonances hosted by nanostructures provide vivid colors that can be used as color filters instead of organic colors and pigments in photodetectors and printing technology. Metallic nanostructures have been widely studied due to their ability to sustain surface plasmons that resonantly interact with light. Most of the metallic nanoparticles behave as point-like electric multipoles. However, the needs of an another degree of freedom to tune the color of the photonic nanostructure together with the use of a reliable and cost-effective material are growing. Here, we report a technique to imprint colored images based on silicon nanoparticles that host low-order electric and magnetic Mie resonances. The interplay between the electric and magnetic resonances leads to a large palette of colors. This all-dielectric fabrication technique offers the advantage to use cost-effective, reliable, and sustainable materials to provide vivid color spanning the whole visible spectrum. The interest and potential of this all-dielectric printing technique are highlighted by reproducing at a micrometer scale a Mondrian painting.

  12. Colors, colored overlays, and reading skills.

    PubMed

    Uccula, Arcangelo; Enna, Mauro; Mulatti, Claudio

    2014-01-01

    In this article, we are concerned with the role of colors in reading written texts. It has been argued that colored overlays applied above written texts positively influence both reading fluency and reading speed. These effects would be particularly evident for those individuals affected by the so called Meares-Irlen syndrome, i.e., who experience eyestrain and/or visual distortions - e.g., color, shape, or movement illusions - while reading. This condition would interest the 12-14% of the general population and up to the 46% of the dyslexic population. Thus, colored overlays have been largely employed as a remedy for some aspects of the difficulties in reading experienced by dyslexic individuals, as fluency and speed. Despite the wide use of colored overlays, how they exert their effects has not been made clear yet. Also, according to some researchers, the results supporting the efficacy of colored overlays as a tool for helping readers are at least controversial. Furthermore, the very nature of the Meares-Irlen syndrome has been questioned. Here we provide a concise, critical review of the literature.

  13. Colors, colored overlays, and reading skills

    PubMed Central

    Uccula, Arcangelo; Enna, Mauro; Mulatti, Claudio

    2014-01-01

    In this article, we are concerned with the role of colors in reading written texts. It has been argued that colored overlays applied above written texts positively influence both reading fluency and reading speed. These effects would be particularly evident for those individuals affected by the so called Meares-Irlen syndrome, i.e., who experience eyestrain and/or visual distortions – e.g., color, shape, or movement illusions – while reading. This condition would interest the 12–14% of the general population and up to the 46% of the dyslexic population. Thus, colored overlays have been largely employed as a remedy for some aspects of the difficulties in reading experienced by dyslexic individuals, as fluency and speed. Despite the wide use of colored overlays, how they exert their effects has not been made clear yet. Also, according to some researchers, the results supporting the efficacy of colored overlays as a tool for helping readers are at least controversial. Furthermore, the very nature of the Meares-Irlen syndrome has been questioned. Here we provide a concise, critical review of the literature. PMID:25120525

  14. Miniature Color Display Phase 4

    DTIC Science & Technology

    1993-05-01

    is used to generate full color. By spectral tuning of the xenon arc-lamp backlight and the color polarizers, a color gamut comparable to that of a...5 1.2 Phase IV Accom plishments ................................... 5 1.2.1 Subtractive Color Gamut ...Technical Achievem ents .............................................. 8 2.1 Subtractive Color Gamut 2.1.1 Sub Color LC Technology

  15. Color Reproduction with a Smartphone

    ERIC Educational Resources Information Center

    Thoms, Lars-Jochen; Colicchia, Giuseppe; Girwidz, Raimund

    2013-01-01

    The world is full of colors. Most of the colors we see around us can be created on common digital displays simply by superposing light with three different wavelengths. However, no mixture of colors can produce a fully pure color identical to a spectral color. Using a smartphone, students can investigate the main features of primary color addition…

  16. Analysis and interpretation of Cassini Titan radar altimeter echoes

    NASA Astrophysics Data System (ADS)

    Zebker, Howard A.; Gim, Yonggyu; Callahan, Philip; Hensley, Scott; Lorenz, Ralph; Cassini Radar Team

    2009-03-01

    The Cassini spacecraft has acquired 25 radar altimeter elevation profiles along Titan's surface as of April 2008, and we have analyzed 18 of these for which there are currently reconstructed ephemeris data. Altimeter measurements were collected at spatial footprint sizes from 6-60 km along ground tracks of length 400-3600 km. The elevation profiles yield topographic information at this resolution with a statistical height accuracy of 35-50 m and kilometer-scale errors several times greater. The data exhibit significant variations in terrain, from flat regions with little topographic expression to very rugged Titanscapes. The bandwidth of the transmitted waveform admits vertical resolution of the terrain height to 35 m at each observed location on the surface. Variations in antenna pointing and changes in surface statistics cause the range-compressed radar echoes to exhibit strong systematic and time-variable biases of hundreds of meters in delay. It is necessary to correct the received echoes for these changes, and we have derived correction algorithms such that the derived echo profiles are accurate at the 100 m level for off-nadir pointing errors of 0.3° and 0.6°, for leading edge and echo centroid estimators, respectively. The leading edge of the echo yields the elevation of the highest points on the surface, which we take to be the peaks of any terrain variation. The mean value of the echo delay is more representative of the mean elevation, so that the difference of these values gives an estimate of any local mountain heights. Finding locations where these values diverge indicates higher-relief terrain. Elevation features are readily seen in the height profiles. Several of the passes show mountains of several hundred m altitude, spread over 10's or even 100's of km in spatial extent, so that slopes are very small. Large expanses of sub-100 m topography are commonplace on Titan, so it is rather smooth in many locations. Other areas exhibit more relief

  17. Modeling of display color parameters and algorithmic color selection

    NASA Astrophysics Data System (ADS)

    Silverstein, Louis D.; Lepkowski, James S.; Carter, Robert C.; Carter, Ellen C.

    1986-01-01

    An algorithmic approach to color selection, which is based on psychophysical models of color processing, is described. The factors that affect color differentiation, such as wavelength separation, color stimulus size, and brightness adaptation level, are discussed. The use of the CIE system of colorimetry and the CIELUV color difference metric for display color modeling is examined. The computer program combines the selection algorithm with internally derived correction factors for color image field size, ambient lighting characteristics, and anomalous red-green color vision deficiencies of display operators. The performance of the program is evaluated and uniform chromaticity scale diagrams for six-color and seven-color selection problems are provided.

  18. Flexible, angle-independent, structural color reflectors inspired by morpho butterfly wings.

    PubMed

    Chung, Kyungjae; Yu, Sunkyu; Heo, Chul-Joon; Shim, Jae Won; Yang, Seung-Man; Han, Moon Gyu; Lee, Hong-Seok; Jin, Yongwan; Lee, Sang Yoon; Park, Namkyoo; Shin, Jung H

    2012-05-08

    Thin-film color reflectors inspired by Morpho butterflies are fabricated. Using a combination of directional deposition, silica microspheres with a wide size distribution, and a PDMS (polydimethylsiloxane) encasing, a large, flexible reflector is created that actually provides better angle-independent color characteristics than Morpho butterflies and which can even be bent and folded freely without losing its Morpho-mimetic photonic properties.

  19. Why Gold and Copper Are Colored but Silver Is Not.

    ERIC Educational Resources Information Center

    Guerrero, Ariel H.; Fasoli, Hector J.; Costa, Jose Luis

    1999-01-01

    Explains why silver, which has the same external electronic configuration as copper and gold, does not appear yellow: white light reflects on most metals without color absorption or change to the naked eye; however, copper and gold appear yellow because they absorb "blue" and "red" photons during electron transitions between…

  20. Top and bottom tensor couplings from a color octet scalar

    NASA Astrophysics Data System (ADS)

    Martinez, Roberto; Valencia, German

    2017-02-01

    We compute the one-loop contributions from a color octet scalar to the tensor anomalous couplings of top and bottom quarks to gluons, photons and W bosons. We use known constraints on the parameters of the model to compare the predicted size of these couplings with existing phenomenological constraints.