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Sample records for narrow emission band

  1. Narrow-band light emission from a single carbon nanotube p-n diode

    NASA Astrophysics Data System (ADS)

    Kinoshita, Megumi; Mueller, Thomas; Steiner, Mathias; Perebeinos, Vasili; Bol, Ageeth; Farmer, Damon; Avouris, Phaedon

    2010-03-01

    We present the first observation of electroluminescence from electrostatically-generated carbon nanotube (CNT) p-n junctions[1]. While CNT optoelectronics has made much progress in recent years, observations of emission from electrically excited CNT devices have been limited to the high-bias regime and with low efficiency. Furthermore, the resulting broad linewidths are broad, making it difficult to investigate electronic levels and carrier dynamics. We find that p-n junctions allow for better carrier control at lower power inputs, resulting in emission with near-zero threshold, low self-heating and efficiency two to three orders of magnitude greater compared to previous device configurations. This yields higher signal-to-noise ratio and narrower linewidths (down to ˜35 meV) that allows us to identify localized excitonic transitions that have previously been observed only in photoluminescent studies. [1] T. Mueller, M. Kinoshita, M. Steiner, V. Perebeinos, A. Bol, D. Farmer, and Ph. Avouris, Nature Nanotech., web publication, November 15 2009.

  2. Direct band gap narrowing in highly doped Ge

    E-print Network

    Han, Zhaohong

    Direct band gap narrowing in highly doped n-type Ge is observed through photoluminescence measurements by determining the spectrum peak shift. A linear relationship between the direct band gap emission and carrier concentration ...

  3. A 1.1-1.9 GHz SETI SURVEY OF THE KEPLER FIELD. I. A SEARCH FOR NARROW-BAND EMISSION FROM SELECT TARGETS

    SciTech Connect

    Siemion, Andrew P. V.; Korpela, Eric; Werthimer, Dan; Cobb, Jeff; Lebofsky, Matt; Marcy, Geoffrey W.; Demorest, Paul; Maddalena, Ron J.; Langston, Glen; Howard, Andrew W.; Tarter, Jill

    2013-04-10

    We present a targeted search for narrow-band (<5 Hz) drifting sinusoidal radio emission from 86 stars in the Kepler field hosting confirmed or candidate exoplanets. Radio emission less than 5 Hz in spectral extent is currently known to only arise from artificial sources. The stars searched were chosen based on the properties of their putative exoplanets, including stars hosting candidates with 380 K > T{sub eq} > 230 K, stars with five or more detected candidates or stars with a super-Earth (R{sub p} < 3 R{sub Circled-Plus }) in a >50 day orbit. Baseband voltage data across the entire band between 1.1 and 1.9 GHz were recorded at the Robert C. Byrd Green Bank Telescope between 2011 February and April and subsequently searched offline. No signals of extraterrestrial origin were found. We estimate that fewer than {approx}1% of transiting exoplanet systems host technological civilizations that are radio loud in narrow-band emission between 1 and 2 GHz at an equivalent isotropically radiated power (EIRP) of {approx}1.5 Multiplication-Sign 10{sup 21} erg s{sup -1}, approximately eight times the peak EIRP of the Arecibo Planetary Radar, and we limit the number of 1-2 GHz narrow-band-radio-loud Kardashev type II civilizations in the Milky Way to be <10{sup -6} M{sub Sun }{sup -1}. Here we describe our observations, data reduction procedures and results.

  4. A 1.1-1.9 GHz SETI Survey of the Kepler Field. I. A Search for Narrow-band Emission from Select Targets

    NASA Astrophysics Data System (ADS)

    Siemion, Andrew P. V.; Demorest, Paul; Korpela, Eric; Maddalena, Ron J.; Werthimer, Dan; Cobb, Jeff; Howard, Andrew W.; Langston, Glen; Lebofsky, Matt; Marcy, Geoffrey W.; Tarter, Jill

    2013-04-01

    We present a targeted search for narrow-band (<5 Hz) drifting sinusoidal radio emission from 86 stars in the Kepler field hosting confirmed or candidate exoplanets. Radio emission less than 5 Hz in spectral extent is currently known to only arise from artificial sources. The stars searched were chosen based on the properties of their putative exoplanets, including stars hosting candidates with 380 K > T eq > 230 K, stars with five or more detected candidates or stars with a super-Earth (R p < 3 R ?) in a >50 day orbit. Baseband voltage data across the entire band between 1.1 and 1.9 GHz were recorded at the Robert C. Byrd Green Bank Telescope between 2011 February and April and subsequently searched offline. No signals of extraterrestrial origin were found. We estimate that fewer than ~1% of transiting exoplanet systems host technological civilizations that are radio loud in narrow-band emission between 1 and 2 GHz at an equivalent isotropically radiated power (EIRP) of ~1.5 × 1021 erg s-1, approximately eight times the peak EIRP of the Arecibo Planetary Radar, and we limit the number of 1-2 GHz narrow-band-radio-loud Kardashev type II civilizations in the Milky Way to be {<}10^{-6}\\ M^{-1}_\\odot. Here we describe our observations, data reduction procedures and results.

  5. Narrow band gap amorphous silicon semiconductors

    DOEpatents

    Madan, A.; Mahan, A.H.

    1985-01-10

    Disclosed is a narrow band gap amorphous silicon semiconductor comprising an alloy of amorphous silicon and a band gap narrowing element selected from the group consisting of Sn, Ge, and Pb, with an electron donor dopant selected from the group consisting of P, As, Sb, Bi and N. The process for producing the narrow band gap amorphous silicon semiconductor comprises the steps of forming an alloy comprising amorphous silicon and at least one of the aforesaid band gap narrowing elements in amount sufficient to narrow the band gap of the silicon semiconductor alloy below that of amorphous silicon, and also utilizing sufficient amounts of the aforesaid electron donor dopant to maintain the amorphous silicon alloy as an n-type semiconductor.

  6. Narrow-band plasmapause HISS observed by ISIS satellites

    NASA Astrophysics Data System (ADS)

    Ondoh, T.

    1993-08-01

    Typical frequency-time spectra of narrow-band hiss obtained near plasmapause latitude from ISIS VLF electric field data (50 Hz to 30 kHz) telemetered at Syowa Station, Antarctica, under quiet conditions, are similar to those of narrow-band 5-kHz hiss observed at midlatitudes and low latitudes on the ground. This hiss in the topside ionosphere first appeared as a thin, bar-shaped emission around 5 kHz at geomagnetic invariant latitude of about 56 deg and grew into a wider band between 3 and 6 kHz at invariant latitudes around 60 deg which is the average plasmapause latitude. Then, at higher latitudes, the band narrowed somewhat and disappeared around 65 deg. The hiss had no lower-frequency cutoff, and its center frequency remained approximately constant at 5 kHz, between about 56 and 65 deg. This narrow-band hiss is completely different from the electrostatic LHR hiss which is also observed above the ionosphere with an electric antenna, but which has latitude-dependent lower-frequency cutoff. Latitude and local time distributions of the occurrence rate for narrow-band plasmapause hiss were obtained by analyzing six-frequency narrow-band data processed from the wideband VLF signals received at Syowa Station from ISIS 1 and ISIS 2 during 507 passes between December 1976 and January 1983.

  7. Efficient, Narrow-Pass-Band Optical Filters

    NASA Technical Reports Server (NTRS)

    Sandford, Stephen P.

    1996-01-01

    Optical filters with both narrow pass bands and high efficiencies fabricated to design specifications. Offer tremendous improvements in performance for number of optical (including infrared) systems. In fiber-optic and free-space communication systems, precise frequency discrimination afforded by narrow pass bands of filters provide higher channel capacities. In active and passive remote sensors like lidar and gas-filter-correlation radiometers, increased efficiencies afforded by filters enhance detection of small signals against large background noise. In addition, sizes, weights, and power requirements of many optical and infrared systems reduced by taking advantage of gains in signal-to-noise ratios delivered by filters.

  8. Narrow-Band Applications of Communications Satellites.

    ERIC Educational Resources Information Center

    Cowlan, Bert; Horowitz, Andrew

    This paper attempts to describe the advantages of "narrow-band" applications of communications satellites for education. It begins by discussing the general controversy surrounding the use of satellites in education, by placing the concern within the larger context of the general debate over the uses of new technologies in education, and by…

  9. Photosensized Controlling Benzyl Methacrylate-Based Matrix Enhanced Eu3+ Narrow-Band Emission for Fluorescence Applications

    PubMed Central

    Lee, Jiann-Fong; Chen, Hsuen-Li; Lee, Geneh-Siang; Tseng, Shao-Chin; Lin, Mei-Hsiang; Liau, Wen-Bin

    2012-01-01

    This study synthesized a europium (Eu3+) complex Eu(DBM)3Cl-MIP (DBM = dibenzoyl methane; Cl-MIP = 2-(2-chlorophenyl)-1-methyl-1H-imidazo[4,5-f][1,10]phenanthroline) dispersed in a benzyl methacrylate (BMA) monomer and treated with ultraviolet (UV) light for polymerization. Spectral results showed that the europium complex containing an antenna, Cl-MIP, which had higher triplet energy into the Eu3+ energy level, was an energetically enhanced europium emission. Typical stacking behaviors of ?–? interactions between the ligands and the Eu3+-ion were analyzed using single crystal X-ray diffraction. Regarding the luminescence performance of this europium composite, the ligand/defect emission was suppressed by dispersion in a poly-BMA (PBMA) matrix. The underlying mechanism of the effective enhancement of the pure Eu3+ emission was attributed to the combined effects of structural modifications, defect emissions, and carrier charge transfer. Fluorescence spectra were compared to the composite of optimized Eu3+ emission where they were subsequently chelated to four metal ions via carboxylate groups on the BMA unit. The optical enhanced europium composite clearly demonstrated highly efficient optical responses and is, therefore a promising application as an optical detection material. PMID:22489178

  10. Narrow band 3 × 3 Mueller polarimetric endoscopy

    PubMed Central

    Qi, Ji; Ye, Menglong; Singh, Mohan; Clancy, Neil T.; Elson, Daniel S.

    2013-01-01

    Mueller matrix polarimetric imaging has shown potential in tissue diagnosis but is challenging to implement endoscopically. In this work, a narrow band 3 × 3 Mueller matrix polarimetric endoscope was designed by rotating the endoscope to generate 0°, 45° and 90° linearly polarized illumination and positioning a rotating filter wheel in front of the camera containing three polarisers to permit polarization state analysis for backscattered light. The system was validated with a rotating linear polarizer and a diffuse reflection target. Initial measurements of 3 × 3 Mueller matrices on a rat are demonstrated, followed by matrix decomposition into the depolarization and retardance matrices for further analysis. Our work shows the feasibility of implementing polarimetric imaging in a rigid endoscope conveniently and economically in order to reveal diagnostic information. PMID:24298405

  11. Electronic structure of an [FeFe] hydrogenase model complex in solution revealed by X-ray absorption spectroscopy using narrow-band emission detection.

    PubMed

    Leidel, Nils; Chernev, Petko; Havelius, Kajsa G V; Schwartz, Lennart; Ott, Sascha; Haumann, Michael

    2012-08-29

    High-resolution X-ray absorption spectroscopy with narrow-band X-ray emission detection, supported by density functional theory calculations (XAES-DFT), was used to study a model complex, ([Fe(2)(?-adt)(CO)(4)(PMe(3))(2)] (1, adt = S-CH(2)-(NCH(2)Ph)-CH(2)-S), of the [FeFe] hydrogenase active site. For 1 in powder material (1(powder)), in MeCN solution (1'), and in its three protonated states (1H, 1Hy, 1HHy; H denotes protonation at the adt-N and Hy protonation of the Fe-Fe bond to form a bridging metal hydride), relations between the molecular structures and the electronic configurations were determined. EXAFS analysis and DFT geometry optimization suggested prevailing rotational isomers in MeCN, which were similar to the crystal structure or exhibited rotation of the (CO) ligands at Fe1 (1(CO), 1Hy(CO)) and in addition of the phenyl ring (1H(CO,Ph), 1HHy(CO,Ph)), leading to an elongated solvent-exposed Fe-Fe bond. Isomer formation, adt-N protonation, and hydride binding caused spectral changes of core-to-valence (pre-edge of the Fe K-shell absorption) and of valence-to-core (Kß(2,5) emission) electronic transitions, and of K? RIXS data, which were quantitatively reproduced by DFT. The study reveals (1) the composition of molecular orbitals, for example, with dominant Fe-d character, showing variations in symmetry and apparent oxidation state at the two Fe ions and a drop in MO energies by ~1 eV upon each protonation step, (2) the HOMO-LUMO energy gaps, of ~2.3 eV for 1(powder) and ~2.0 eV for 1', and (3) the splitting between iron d(z(2)) and d(x(2)-y(2)) levels of ~0.5 eV for the nonhydride and ~0.9 eV for the hydride states. Good correlations of reduction potentials to LUMO energies and oxidation potentials to HOMO energies were obtained. Two routes of facilitated bridging hydride binding thereby are suggested, involving ligand rotation at Fe1 for 1Hy(CO) or adt-N protonation for 1HHy(CO,Ph). XAES-DFT thus enables verification of the effects of ligand substitutions in solution for guided improvement of [FeFe] catalysts. PMID:22860512

  12. A narrow-band speckle-free light source via random Raman lasing

    E-print Network

    Hokr, Brett H; Bixler, Joel N; Dyer, Phillip N; Noojin, Gary D; Redding, Brandon; Thomas, Robert J; Rockwell, Benjamin A; Cao, Hui; Yakovlev, Vladislav V; Scully, Marlan O

    2015-01-01

    Currently, no light source exists which is both narrow-band and speckle-free with sufficient brightness for full-field imaging applications. Light emitting diodes (LEDs) are excellent spatially incoherent sources, but are tens of nanometers broad. Lasers on the other hand can produce very narrow-band light, but suffer from high spatial coherence which leads to speckle patterns which distort the image. Here we propose the use of random Raman laser emission as a new kind of light source capable of providing short-pulsed narrow-band speckle-free illumination for imaging applications.

  13. The Narrow-Band Model and Semi-Conductor Theory

    ERIC Educational Resources Information Center

    Tanner, B. K.

    1976-01-01

    Applies the narrow-band model to the instruction of intrinsic and extrinsic semiconductors along with the phenomenon of compensation. Advocates the model for undergraduate instruction due to its intuitive appeal and mathematical simplicity. (CP)

  14. The electronic structure of heavy fermions: Narrow temperature independent bands

    SciTech Connect

    Arko, A.J.; Joyce, J.J.; Smith, J.L.; Andrews, A.B.

    1996-08-01

    The electronic structure of both Ce and U heavy fermions appears to consist of extremely narrow temperature independent bands. There is no evidence from photoemission for a collective phenomenon normally referred to as the Kondo resonance. In uranium compounds a small dispersion of the bands is easily measurable.

  15. Ultrafast Narrow Band Modulation of VCSELs

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    Multimode beating was greatly enhanced by taking output from part (e.g., half) of the output facet. Simpler sources of microwaves and millimeter waves of various frequencies were generated by varying the VCSEL diameter in a single multimode VCSEL our coupling of a few VCSELs. Breathing frequency in multi-mode operations affects modulation response and bandwidth. Optimizing RO frequency and mode beating frequency could potentially expand bandwidths suitable for wide band digital communications.

  16. Fabry-Perot interferometers as narrow band optical filters.

    NASA Technical Reports Server (NTRS)

    Title, A. M.

    1971-01-01

    We have constructed solid Fabry-Perot narrow-band filters that can be used in systems having one arc second or better resolution. Our filters operate at H-alpha, have a three-inch aperture, and typical transmission of 70 per cent. However, the same technology can be applied to construction of filters as narrow as 0.05 A at any wavelength from 4200 to 11000 A.

  17. Narrow-Band WGM Optical Filters With Tunable FSRs

    NASA Technical Reports Server (NTRS)

    Mohageg, Makan; Matsko, Andrey; Savchenkov, Anatoliy; Maleki, Lute; Iltchenko, Vladimir; Strekalov, Dmitry

    2007-01-01

    Optical resonators of the whispering-gallery-mode (WGM) type featuring DC-tunable free spectral ranges (FSRs) have been demonstrated. By making the FSR tunable, one makes it possible to adjust, during operation, the frequency of a microwave signal generated by an optoelectronic oscillator in which an WGM optical resonator is utilized as a narrow-band filter.

  18. Narrow-Band Thermal Radiation Based on Microcavity Resonant Effect

    NASA Astrophysics Data System (ADS)

    Huang, Jin-Guo; Xuan, Yi-Min; Li, Qiang

    2014-09-01

    The microcavity resonant effect is used to realize narrow-band thermal radiation. Periodic circular aperture arrays with square lattice are patterned on Si substrates by using standard photolithographic techniques and reactive ion etching techniques. Ag films are deposited on the surface of Si substrates with aperture arrays to improve the infrared reflectance. On the basis of the micromachining process, an Ag/Si structured surface exhibiting narrow-band radiation and directivity insensitivity is presented. The emittance spectra exhibit several selective emittance bands attributed to the microcavity resonance effect. The dependence of emittance spectra on sizes and direction is also experimentally examined. The results indicate that the emittance peak of the Ag/Si structured surface can be modulated by tailoring the structural sizes. Moreover, the emittance peak is independent of the radiant angle, which is very important for designing high-performance thermal emitters.

  19. Narrow-band single photon emission at room temperature based on a single nitrogen-vacancy center coupled to an all-fiber-cavity

    SciTech Connect

    Albrecht, Roland; Bommer, Alexander; Becher, Christoph; Pauly, Christoph; Mücklich, Frank; Schell, Andreas W.; Engel, Philip; Benson, Oliver; Schröder, Tim; Reichel, Jakob

    2014-08-18

    We report the realization of a device based on a single Nitrogen-Vacancy (NV) center in diamond coupled to a fiber-cavity for use as single photon source (SPS). The device consists of two concave mirrors each directly fabricated on the facets of two optical fibers and a preselected nanodiamond containing a single NV center deposited onto one of these mirrors. Both, cavity in- and out-put are directly fiber-coupled, and the emission wavelength is easily tunable by variation of the separation of the two mirrors with a piezo-electric crystal. By coupling to the cavity, we achieve an increase of the spectral photon rate density by two orders of magnitude compared to free-space emission of the NV center. With this work, we establish a simple all-fiber based SPS with promising prospects for the integration into photonic quantum networks.

  20. Latitude dependence of narrow bipolar pulse emissions

    NASA Astrophysics Data System (ADS)

    Ahmad, M. R.; Esa, M. R. M.; Cooray, V.; Baharudin, Z. A.; Hettiarachchi, P.

    2015-06-01

    In this paper, we present a comparative study on the occurrence of narrow bipolar pulses (NBPs) and other forms of lightning flashes across various geographical areas ranging from northern regions to the tropics. As the latitude decreased from Uppsala, Sweden (59.8°N) to South Malaysia (1.5°N), the percentage of NBP emissions relative to the total number of lightning flashes increased significantly from 0.13% to 12%. Occurrences of positive NBPs were more common than negative NBPs at all observed latitudes. However, as latitudes decreased, the negative NBP emissions increased significantly from 20% (Uppsala, Sweden) to 45% (South Malaysia). Factors involving mixed-phase region elevations and vertical extents of thundercloud tops are invoked to explain the observed results. These factors are fundamentally latitude dependent. Our results suggest that the NBP emission rate is not a useful measure to monitor thunderstorm severity because regular tropical thunderstorms, where relatively high NBP emissions occur, lack suitable conditions to become severe (i.e., there is modest convective available potential energy and a lack of baroclinity in such regions). Observations of significantly high negative NBP occurrences together with very rare occurrences of positive cloud-to-ground flashes and isolated breakdown pulses in tropical thunderstorms are indicative of a stronger negative screening layer magnitude and weaker lower positive charge region magnitude than those in northern regions.

  1. Frequency shifting of pulsed narrow-band laser light in a multipass Raman cell

    NASA Astrophysics Data System (ADS)

    Su?mann, R.; Weber, Th.; Riedle, E.; Neusser, H. J.

    1992-04-01

    A multipass cell is described which allows efficient stimulated Raman frequency shifting for low pump laser intensities and low gas pressures. The latter is important for Raman shifting of narrow-band Fourier-transform limited light pulses (? v=75 MHz). It is shown that frequency broadening of the Raman shifted light can be largely avoided in the Dicke narrowing regime at low pressures. For 75 MHz pump pulses and an H 2 density of 2.5 amagat we found a negligible broadening to 90 MHz of the stimulated Stokes light. This is far below the value of 250 MHz expected from spontaneous emission. The narrow-band Stokes pulses achieved in CO 2 enabled us to measure the pressure shift coefficient (-0.71×10 -2 cm -1/amagat) of this gas. It is demonstrated, for the example of benzene, that our technique provides a very practical light source for high resolution molecular spectroscopy.

  2. Compact narrow-band THz radiation source based on photocathode rf gun

    NASA Astrophysics Data System (ADS)

    Li, Wei-Wei; He, Zhi-Gang; Jia, Qi-Ka

    2014-04-01

    Narrow-band THz coherent Cherenkov radiation can be driven by a subpicosecond electron bunch traveling along the axis of a hollow cylindrical dielectric-lined waveguide. We present a scheme of compact THz radiation source based on the photocathode rf gun. On the basis of our analytic result, the subpicosecond electron bunch with high charge (800 pC) can be generated directly in the photocathode rf gun. According to the analytical and simulated results, a narrow emission spectrum peaked at 0.24 THz with 2 megawatt (MW) peak power is expected to gain in the proposed scheme (the length of the facility is about 1.2 m).

  3. Advanced Imaging Technology Other than Narrow Band Imaging

    PubMed Central

    Cho, Jun-Hyung

    2015-01-01

    To improve the detection rate of gastrointestinal tumors, image-enhanced endoscopy has been widely used during screening and surveillance endoscopy in Korea. In addition to narrow band imaging (NBI) with/without magnification, various types of electronic chromoendoscopies have been used, including autofluorescence imaging, I-scan, and flexible spectral imaging color enhancement. These technologies enable the accurate characterization of tumors because they enable visualization of microvascular and microsurface patterns. The present review focuses on understanding the principle and clinical applications of advanced imaging technologies other than NBI. PMID:26668796

  4. Emerging role of narrow band imaging in duodenum

    PubMed Central

    Dutta, Amit Kumar; Chacko, Ashok

    2015-01-01

    Endoscopy using magnification narrow band imaging (mNBI) allows detailed assessment of mucosal surface and vascular pattern. This may help in better identification and prediction of the nature of the lesion. The role of this technology in duodenum is still evolving. Studies have shown that mNBI has high accuracy in predicting villous atrophy in the duodenum. Limited data suggests that this technique can provide additional information on duodenal polyps, nodules and ampullary tumour which can help guide their management. In this paper we describe the technique for duodenal assessment using NBI and review the existing literature evaluating its role in diagnosis of various duodenal pathologies. PMID:26566428

  5. Fatigue failure of materials under narrow band random vibrations. I.

    NASA Technical Reports Server (NTRS)

    Huang, T. C.; Hubbard, R. B.; Lanz, R. W.

    1971-01-01

    A novel approach for the study of fatigue failure of materials under the multifactor influence of narrow band random vibrations is developed. The approach involves the conduction of an experiment in conjunction with various statistical techniques. Three factors including two statistical properties of the excitation or response are considered and varied simultaneously. A minimum of 6 tests for 3 variables is possible for a fractional f actorial design. The four coefficients of the predicting equation can be independently estimated. A look at 3 predicting equations shows the predominant effect of the root mean square stress of the first order equation.

  6. Narrow-Band Biphoton Generation near Atomic Resonance

    E-print Network

    Shengwang Du; Jianming Wen; Morton H. Rubin

    2008-04-24

    Generating nonclassical light offers a benchmark tool for the fundamental research and potential applications in quantum optics. Conventionally, it has become a standard technique to produce the nonclassical light through the nonlinear optical processes occurring in nonlinear crystals. In this review we describe using cold atomic-gas media to generate such nonclassical light, especially focusing on narrow-band biphoton generation. Compared with the standard procedure, the new biphoton source has such properties as long coherence time, long coherence length, high spectral brightness, and high conversion efficiency. In this paper we concentrate on the theoretical aspect of the entangled two-photon state produced from the four-wave mixing in a multilevel atomic ensemble. We show that both linear and nonlinear optical responses to the generated fields play an important role in determining the biphoton waveform and, consequently on the two-photon temporal correlation. There are two characteristic regimes determined by whether the linear or nonlinear coherence time is dominant. In addition, our model provides a clear physical picture that brings insight into understanding biphoton optics with this new source. We apply our model to recent work on generating narrow-band (and even subnatural linewidth) paired photons using the technique of electromagnetically induced transparency and slow-light effect in cold atoms, and find good agreements with experimental results.

  7. NIR Narrow- and Broad-Band Study of the SSA 22 Field

    NASA Astrophysics Data System (ADS)

    Tamura, Naoyuki; Ohta, Kouji; Maihara, Toshinori; Iwamuro, Fumihide; Motohara, Kentaro; Takata, Tadafumi; Iye, Masanori

    2001-08-01

    Deep narrow- and broad-band near-infrared imaging observations of the central 2'×2' region of the SSA 22 field were made with the near-infrared camera (CISCO) attached to the Subaru Telescope. Using a narrow-band filter centered at 2.033?m, [O III] ?5007 emitters at z ~ 3.06 +/- 0.02 were searched to examine star-forming activities in an over-density region where a clustering of Lyman Break Galaxies (LBGs) and Lyman ? emitter candidates around z = 3.09 was reported, though the targeted redshift is slightly different from that of the peak of the over-density region. Although one emitter candidate at z = 3.06 was detected, it is likely to be located at a redshift of between 1 and 2 judged based on multi-band photometry. Another emission-line object was detected in another narrow-band filter (``off band'' filter) centered at 2.120 ?m, which is identified with a galaxy at z = 0.132 (the emission line is Paschen ?). The K'-band imaging data revealed the presence of 12 Extremely Red Objects (EROs) with I814-K' gep 4. The distribution of the EROs does not seem to coincide with that of Lyman Break Galaxies or Lyman alpha; emitters at z ~ 3. The magnitudes and colors of the EROs are not consistent with those of passively evolving massive elliptical galaxies at z ~ 3. Candidates for counterparts of the submm sources detected with SCUBA are found; no EROs around the submm sources are found in our magnitude limit.

  8. Narrow Band Imaging: Technology Basis and Research and Development History

    PubMed Central

    Gono, Kazuhiro

    2015-01-01

    The first launch of narrow band imaging (NBI) was in 2005. Since then, in most countries where gastrointestinal endoscopies are performed, NBI is the most commonly used optical digital method of performing image-enhanced endoscopy. Thanks to the outstanding efforts of many endoscopists, many clinical studies have been performed and clinical evidence has been gathered. In Japan, since 2010, NBI has been reimbursed under the Japanese national health insurance system. This is owing to the establishment of clinical evidence by physicians. However, even though endoscope systems with NBI function have been widely used outside of Japan, dissemination of knowledge on how to use NBI is insufficient. In this review paper, the technology basis of NBI and its research and development history are described. I hope this information will be helpful for updating physicians’ knowledge of NBI. PMID:26668792

  9. NARROW-K-BAND OBSERVATIONS OF THE GJ 1214 SYSTEM

    SciTech Connect

    Colón, Knicole D.; Gaidos, Eric

    2013-10-10

    GJ 1214 is a nearby M dwarf star that hosts a transiting super-Earth-size planet, making this system an excellent target for atmospheric studies. Most studies find that the transmission spectrum of GJ 1214b is flat, which favors either a high mean molecular weight or cloudy/hazy hydrogen (H) rich atmosphere model. Photometry at short wavelengths (<0.7 ?m) and in the K band can discriminate the most between these different atmosphere models for GJ 1214b, but current observations do not have sufficiently high precision. We present photometry of seven transits of GJ 1214b through a narrow K-band (2.141 ?m) filter with the Wide Field Camera on the 3.8 m United Kingdom Infrared Telescope. Our photometric precision is typically 1.7 × 10{sup –3} (for a single transit), comparable with other ground-based observations of GJ 1214b. We measure a planet-star radius ratio of 0.1158 ± 0.0013, which, along with other studies, also supports a flat transmission spectrum for GJ 1214b. Since this does not exclude a scenario where GJ 1214b has an H-rich envelope with heavy elements that are sequestered below a cloud/haze layer, we compare K-band observations with models of H{sub 2} collision-induced absorption in an atmosphere for a range of temperatures. While we find no evidence for deviation from a flat spectrum (slope s = 0.0016 ± 0.0038), an H{sub 2}-dominated upper atmosphere (<60 mbar) cannot be excluded. More precise observations at <0.7 ?m and in the K band, as well as a uniform analysis of all published data, would be useful for establishing more robust limits on atmosphere models for GJ 1214b.

  10. Superscattering-enhanced narrow band forward scattering antenna

    NASA Astrophysics Data System (ADS)

    Hu, De-Jiao; Zhang, Zhi-You; Du, Jing-Lei

    2015-10-01

    We present a narrow band forward scattering optical antenna which is based on the excitation of distinctive whispering gallery modes (WGMs). The antenna is composed of three coaxial cylinder layers: a dielectric layer is sandwiched between a metallic core and cladding. Owing to the destructive interference between the scattering of the outer metallic cladding and the WGM in the backward direction, the power flow in the forward direction is increased. Simulation and analysis show that in proper geometry conditions, the cavity can be tuned into a superscattering state. At this state, both the zeroth and the first order of WGM are excited and contribute to the total scattering. It is shown that the power ratio (power towards backward divided by power towards forward) can be enhanced to about 27 times larger than that for a non-resonant position by the superscattering. Owing to the confinement of the cladding to WGMs, the wavelength range of effective forward scattering is considerably narrow (about 15 nm). Project supported by the National Natural Science Foundation of China (Grant No. 61377054), the Collaborative Innovation Foundation of Sichuan University, China (Grant No. XTCX 2013002), and the International Cooperation and Exchange of Science and Technology Project in Sichuan Province, China (Grant No. 2013HH0010).

  11. PAU, a fully depleted mosaic imager with narrow band filters

    NASA Astrophysics Data System (ADS)

    Bauer, A.; Casas, R.; Castander, F. J.; Serrano, S.

    2014-03-01

    The PAU Survey studies the existence and properties of dark energy from the observations of redshift space distortions and weak lensing magnification from galaxy cross-correlations as main cosmological probes. The PAU Team is building an instrument, PAUCam, equipped with fully depleted CCD detectors, designed to be mounted at the prime focus of the 4.2 m diameter William Herschel Telescope (WHT) in La Palma. Simulations indicate that PAUCam at the WHT will be able to image about 2 square degrees per night in 40 narrow-band filters plus six wide-band filters to an AB magnitude depth of i ~ 22.5, providing low-resolution (R ~ 50) photometric spectra for around 30,000 galaxies, 5,000 stars and 1,000 quasars per square degree. Accurate photometric calibration of the PAU data is vital to achieve the survey science goals. This calibration is challenging due to the large and unusual filter set. We outline the data management pipelines being developed for the survey, both for nightly data reduction and co-addition of multiple epochs, with emphasis on the photometric calibration strategies. We also describe the main tests and results in the characterization of our Hamamatsu fully depleted detectors.

  12. Narrow band gap conjugated polymers for emergent optoelectronic technologies

    NASA Astrophysics Data System (ADS)

    Azoulay, Jason D.; Zhang, Benjamin A.; London, Alexander E.

    2015-09-01

    Conjugated organic molecules effectively produce and harvest visible light and find utility in a variety of emergent optoelectronic technologies. There is currently interest in expanding the scope of these materials to extend functionality into the infrared (IR) spectral regions and endow functionality relevant in emergent technologies. Developing an understanding of the interplay between chemical and electronic structure in these systems will require control of the frontier orbital energetics (separation, position, and alignment), ground state electronic configurations, interchain arrangements, solid-state properties, and many other molecular features with synthetic precision that has yet to be demonstrated. Bridgehead imine substituted 4H-cyclopenta[2,1-b:3,4-b']dithiophene (CPDT) structural units, in combination with strong acceptors with progressively delocalized ?-systems, afford modular donor-acceptor copolymers with broad and long wavelength absorption that spans technologically relevant wavelength (?) ranges from 0.7 < ? < 3.2 ?m.1 Here we demonstrate that electronic and structural manipulation play a major role in influencing the energetics of these systems and ultimately controlling the band gap of the materials. These results bear implication in the development of very narrow band gap systems where precise control will be necessary for achieving desired properties such as interactions with longer wavelength light.

  13. Narrow-Band Emitting Solid Fluorescence Reference Standard with Certified Intensity Pattern.

    PubMed

    Hoffmann, Katrin; Spieles, Monika; Bremser, Wolfram; Resch-Genger, Ute

    2015-07-21

    The development of a lanthanum-phosphate glass doped with several rare-earth-ions for use as solid fluorescence standard is described. The cuvette-shaped reference material which shows a characteristic emission intensity pattern upon excitation at 365 nm consisting of a multitude of relatively narrow emission bands in the wavelength region between 450 and 700 nm is intended for the day-to-day performance validation of fluorescence measuring devices. Evaluation of the fluorescent glass includes the determination of all properties which can affect its relative emission intensity profile or contribute to the uncertainty of the certified values like absorption spectra, fluorescence anisotropy, excitation wavelength, and temperature dependence of the spectroscopic features, homogeneity of fluorophore distribution, and photo- and long-term stability. Moreover, a certification procedure was developed including the normalization of the intensity profile consisting of several narrow emission bands and the calculation of wavelength-dependent uncertainties. Criteria for the design, characterization, and working principle of the new reference material BAM-F012 are presented, and possible applications of this ready-to-use fluorescence standard are discussed. PMID:26077510

  14. Monaural envelope correlation perception for bands narrower or wider than a critical band

    PubMed Central

    Buss, Emily; Hall, Joseph W.; Grose, John H.

    2013-01-01

    Monaural envelope correlation perception concerns the ability of listeners to discriminate stimuli based on the degree of correlation between the temporal envelopes of two or more frequency-separated bands of noise [Richards, J. Acoust. Soc. Am. 82, 1621–1630 (1987)]. Previous work has examined this ability for relatively narrow bandwidths, generally 100?Hz or less. The present experiment explored a wide range of bandwidths, from 25 to 1600?Hz, which included bands narrower and wider than a critical bandwidth. Stimuli were pairs of noise bands separated by a 500-Hz-wide spectral gap centered on 2250?Hz. The magnitude spectra of the pair of comodulated bands were either identical or reflected around the midpoint of the band, and performance was assessed with and without a low-pass noise masker. Although discrimination was best for intermediate bandwidths, mean performance was above chance for all bandwidths tested. Data were similar for stimuli with identical and reflected magnitude spectra, and for stimuli with and without the low-pass masker. The one exception was particularly good performance for intermediate-bandwidth stimuli with identical spectra, for which some listeners reported hearing a tonal cue. Results indicate that listeners are flexible in selecting spectral regions upon which to base across-frequency comparisons. PMID:23297912

  15. Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes

    SciTech Connect

    Nong, Hanond Markmann, Sergej; Hekmat, Negar; Jukam, Nathan; Pal, Shovon; Mohandas, Reshma A.; Dean, Paul; Li, Lianhe; Linfield, Edmund H.; Giles Davies, A.; Wieck, Andreas D.

    2014-09-15

    A periodically poled lithium niobate (PPLN) crystal with multiple poling periods is used to generate tunable narrow-bandwidth THz pulses for injection seeding a quantum cascade laser (QCL). We demonstrate that longitudinal modes of the quantum cascade laser close to the gain maximum can be selected or suppressed according to the seed spectrum. The QCL emission spectra obtained by electro-optic sampling from the quantum cascade laser, in the most favorable case, shows high selectivity and amplification of the longitudinal modes that overlap the frequency of the narrow-band seed. Proper selection of the narrow-band THz seed from the PPLN crystal discretely tunes the longitudinal mode emission of the quantum cascade laser. Moreover, the THz wave build-up within the laser cavity is studied as a function of the round-trip time. When the seed frequency is outside the maximum of the gain spectrum the laser emission shifts to the preferential longitudinal mode.

  16. H2 and Br-gamma narrow-band imaging of bipolar planetary nebulae

    E-print Network

    M. A. Guerrero; E. Villaver; A. Manchado; P. Garcia-Lario; F. Prada

    1999-10-20

    We present near-IR narrow-band continuum-subtracted images in the H$_2$ $2.122\\mu$m, and Br$\\gamma$ $2.166\\mu$m emission lines for a sample of 15 bipolar planetary nebulae. H$_2$ emission was definitely detected for most of the objects in this sample (13 out of 15). The very high H$_2$ detection rate supports the idea that bipolar planetary nebulae have important reservoirs of molecular material and offer suitable physical conditions for the excitation of H$_2$. The strength of the H$_2$ emission and the H$_2$/Br$\\gamma$ flux ratio are found to correlate with the morphology of the bipolar nebulae observed. Bipolar PNe with broad and bright rings exhibit stronger H$_2$ emission than bipolar PNe with narrow twists. High-quality (sub-arcsec) [N~{\\sc ii}] and H$\\alpha$ optical images have been used to compare the distribution of the ionized and molecular material. The H$_2$ emission lies just outside the optical [N~{\\sc ii}] emission zone.

  17. Narrow-band erbium-doped fibre linear–ring laser

    SciTech Connect

    Kolegov, A A; Sofienko, G S; Minashina, L A; Bochkov, A V

    2014-01-31

    We have demonstrated a narrow-band linear – ring fibre laser with an output power of 15 mW at a wavelength of 1.55 ?m and an emission bandwidth less than 5 kHz. The laser frequency is stabilised by an unpumped active fibre section and fibre Bragg grating. The fibre laser operates in a travelling wave mode, which allows the spatial hole burning effect to be avoided. At a certain pump power level, the laser switches from continuous mode to repetitivepulse operation, corresponding to relaxation oscillations. (control of laser radiation parameters)

  18. 2 um Narrow-Band Imaging of the Sagittarius D H II region

    E-print Network

    R. D. Blum; A. Damineli

    1998-09-27

    We present 2 um narrow-band images of the core H II region in the Galactic star forming region Sagittarius D. The emission-line images are centered on 2.17 um (Brgamma) and 2.06 um (He I). The H II region appears at the edge of a well defined dark cloud, and the morphology suggests a blister geometry as pointed out in earlier radio continuum work. There is a deficit of stars in general in front of the associated dark cloud indicating the H II region is located in-between the Galactic center and the sun. The lesser spatial extent of the He I line emission relative to Brgamma places the effective temperature of the ionizing radiation field below 40,000 K. The He I 2.06 um to Brgamma ratio and Brgamma / far infrared dust emission put Teff at about 36,500 K to 40,000 K as derived from ionization models.

  19. Observation of Narrow-Band Terahertz Coherent Cherenkov Radiation from a Cylindrical Dielectric-Lined Waveguide

    SciTech Connect

    Cook, A. M.; Tikhoplav, R.; Travish, G.; Williams, O. B.; Rosenzweig, J. B.; Tochitsky, S. Y.

    2009-08-28

    We report experimental observation of narrow-band coherent Cherenkov radiation driven by a subpicosecond electron bunch traveling along the axis of a hollow cylindrical dielectric-lined waveguide. For an appropriate choice of dielectric wall thickness, a short-pulse beam current profile excites only the fundamental mode of the structure, producing energetic pulses in the terahertz range. We present detailed measurements showing a narrow emission spectrum peaked at 367+-3 GHz from a 1 cm long fused silica capillary tube with submillimeter transverse dimensions, closely matching predictions. We demonstrate a 100 GHz shift in the emitted central frequency when the tube wall thickness is changed by 50 mum. Calibrated measurements of the radiated energy indicate up to 10 muJ per 60 ps pulse for an incident beam charge of 200 pC, corresponding to a peak power of approximately 150 kW.

  20. Narrow-band ultraviolet-B stimulates proliferation and migration of cultured melanocytes.

    PubMed

    Wu, Ching-Shuang; Yu, Chia-Li; Wu, Chieh-Shan; Lan, Cheng-Che E; Yu, Hsin-Su

    2004-12-01

    Narrow-band ultraviolet-B (UVB) radiation is an effective treatment for vitiligo vulgaris. However, the mechanisms of narrow-band UVB in inducing repigmentation of vitiligo lesions are not thoroughly clarified. The purpose of our study was to investigate the effects of narrow-band UVB irradiation on melanocyte proliferation and migration in vitro. Our results showed that the cell counts as well as [3H]thymidine uptake of melanocytes were significantly enhanced by narrow-band UVB-irradiated keratinocyte supernatants. In these supernatants, a significant increase in basic fibroblast growth factor (bFGF) and in endothelin-1 (ET-1) release was observed. bFGF is a natural mitogen for melanocytes, whereas ET-1 can stimulate DNA synthesis in melanocytes. This stimulatory effect of melanocyte proliferation by supernatants derived from narrow-band UVB-irradiated keratinocytes was significantly reduced by a selective endothelin-B (ET-B) receptor antagonist (BQ788), suggesting an essential role of ET-1 on melanocyte proliferation. Our results of time-lapse microphotography revealed a stimulatory effect of narrow-band UVB irradiation on melanocyte migration. Focal adhesion kinase (FAK) plays a pivotal role in cell migration. Phosphorylated FAK (p125(FAK)) expression on melanocyte was enhanced by narrow-band UVB irradiation. In this study, narrow-band UVB irradiation stimulated a significant increase in matrix metalloproteinase-2 (MMP-2) activity in melanocyte supernatants. Narrow-band UVB-irradiation-induced migration of melanocytes was significantly annihilated by the addition of p125(FAK) inhibitor (herbimycin-A) or MMP-2 inhibitor (GM6001). These results suggest that p125(FAK) and MMP-2 activity play important roles in narrow-band UVB-induced migration of melanocytes. Our results provide a theoretical basis for the effectiveness of narrow-band UVB irradiation in treating vitiligo. PMID:15560759

  1. Whispering-Gallery-Mode Tunable Narrow-Band-Pass Filter

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy; Iltchenko, Vladimir; Matsko, Andrey; Maleki, Lute

    2004-01-01

    An experimental tunable, narrow-band-pass electro-optical filter is based on a whispering-gallery resonator. This device is a prototype of tunable filters needed for the further development of reconfigurable networking wavelength-division multiplexers and communication systems that utilize radio-frequency (more specifically, microwave) subcarrier signals on optical carrier signals. The characteristics of whispering-gallery resonators that make them attractive for such applications include high tuning speed, compactness, wide tuning range, low power consumption, and compatibility with single-mode optical fibers. In addition, relative to Fabry-Perot resonators, these devices offer advantages of greater robustness and lower cost. As described in several prior NASA Tech Briefs articles, a whispering-gallery resonator is a spheroidal, disk-like, or toroidal body made of a highly transparent material. It is so named because it is designed to exploit whispering-gallery electromagnetic modes, which are waveguide modes that propagate circumferentially and are concentrated in a narrow toroidal region centered on the equatorial plane and located near the outermost edge. The experimental whispering-gallery tunable filter (see figure) is made from a disk of Z-cut LiNbO3 of 4.8-mm diameter and 0.17-mm thickness. The perimeter of the disk is rounded to a radius of curvature of 100 m. Metal coats on the flat faces of the disk serve as electrodes for exploiting the electro-optical effect in LiNbO3 for tuning. There is no metal coat on the rounded perimeter region, where the whispering-gallery modes propagate. Light is coupled from an input optical fiber into the whispering-gallery modes by means of a diamond prism. Another diamond prism is used to couple light from the whispering-gallery modes to an output optical fiber. This device is designed and operated to exploit transverse magnetic (TM) whispering- gallery modes, rather than transverse electric (TE) modes because the resonance quality factors (Q values) of the TM modes are higher. If Q values were not of major concern, it would be better to use the TE modes because the electro-optical shifts of the TE modes are 3 times those of the TM modes.

  2. Narrow-Band Processing and Fusion Approach for Explosive Hazard Detection in FLGPR

    E-print Network

    Havens, Timothy

    Narrow-Band Processing and Fusion Approach for Explosive Hazard Detection in FLGPR Timothy C. Keywords: forward-looking explosive hazards detection, ground-penetrating radar, narrow-band processing, false alarm rejection, fusion, Gabor filters 1. INTRODUCTION Remediation of the threat of explosive

  3. Differential-phase-shift quantum key distribution using heralded narrow-band

    E-print Network

    Du, Shengwang

    Differential-phase-shift quantum key distribution using heralded narrow-band single photons Chang differential phase shift (DPS) quantum key distribution (QKD) using narrow-band heralded single photons). 2. C. H. Bennett and G. Brassard, "Quantum cryptography: Public key distribution and coin tossing

  4. 47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Narrow-band direct-printing (NB-DP). 80.1159... Narrow-band direct-printing (NB-DP). NB-DP is a form of telegraphy for the transmission and receipt of direct printing public correspondence. Ships must use NB-DP techniques only with authorized public...

  5. 47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Narrow-band direct-printing (NB-DP). 80.1159... Narrow-band direct-printing (NB-DP). NB-DP is a form of telegraphy for the transmission and receipt of direct printing public correspondence. Ships must use NB-DP techniques only with authorized public...

  6. 47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Narrow-band direct-printing (NB-DP). 80.1159... Narrow-band direct-printing (NB-DP). NB-DP is a form of telegraphy for the transmission and receipt of direct printing public correspondence. Ships must use NB-DP techniques only with authorized public...

  7. 47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Narrow-band direct-printing (NB-DP). 80.1159... Narrow-band direct-printing (NB-DP). NB-DP is a form of telegraphy for the transmission and receipt of direct printing public correspondence. Ships must use NB-DP techniques only with authorized public...

  8. 47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Narrow-band direct-printing (NB-DP). 80.1159... Narrow-band direct-printing (NB-DP). NB-DP is a form of telegraphy for the transmission and receipt of direct printing public correspondence. Ships must use NB-DP techniques only with authorized public...

  9. Broadening of effective photonic band gaps in biological chiral structures: From intrinsic narrow band gaps to broad band reflection spectra

    NASA Astrophysics Data System (ADS)

    Vargas, W. E.; Hernández-Jiménez, M.; Libby, E.; Azofeifa, D. E.; Solis, Á.; Barboza-Aguilar, C.

    2015-09-01

    Under normal illumination with non-polarized light, reflection spectra of the cuticle of golden-like and red Chrysina aurigans scarabs show a structured broad band of left-handed circularly polarized light. The polarization of the reflected light is attributed to a Bouligand-type left-handed chiral structure found through the scarab's cuticle. By considering these twisted structures as one-dimensional photonic crystals, a novel approach is developed from the dispersion relation of circularly polarized electromagnetic waves traveling through chiral media, to show how the broad band characterizing these spectra arises from an intrinsic narrow photonic band gap whose spectral position moves through visible and near-infrared wavelengths.

  10. Narrow band imaging and long slit spectroscopy of UGC 5101

    NASA Astrophysics Data System (ADS)

    Stanga, R. M.; Mannucci, F.; Rodríguez Espinosa, J. M.

    1993-01-01

    UGC 5101 (z = 0.04; D is approximately equal to 240 Mpc) is one of the so called Ultraluminous IRAS sources. Two important properties of the members of this group are their L(sub IR) is greater than or equal to 10(exp 12) solar luminosity, and their space density in the universe up to z is less than 0.1 is equal or even larger than the space density of the quasars. Further noteworthy features of the Ultraluminous IRAS sources are their being morphologically peculiar and the fact that they all seem to host active nuclei in their center. We have observed UGC 5101 in an effort to study the interplay between the gas ionized by the central active nucleus and that gas ionized by other processes which may hold important clues to the understanding of the entire picture of this object. In particular these other ionizing processes could well be massive stars formed recently after the galactic encounter and shocks possibly also related to the galaxy collision. The data that we discuss were obtained between Dec. 1989 and Jan. 1992 with the WHT 4.2 m telescope using the two-arm spectrograph ISIS. Several spectral frames were obtained at three different position angles: PA 84--along the tail of the galaxy; PA 32--along the dust lane; and PA 110. The blue spectra are centered on the H beta line, while the red spectra are centered on the H alpha line. In the configuration we used for the long slit spectra, the spectral scale was 0.74 A per pixel, and the spatial scale was .37 arcsec per pixel; we also observed the H alpha region with a spectral scale of .37 A per pixel, at position angle 84. The narrow band images were obtained at the auxiliary port of ISIS, with a scale of .2 arcsec per pixel, and were centered at the H alpha wavelength, and on the adjacent continuum. The H alpha images and the spectra support the following model. UGC 5101 hosts an active nucleus; the NLR extends up to about 1.5 kpc and shows a complex velocity field, superimposed on the rotation curve of the galaxy. Besides the NLR, in the H alpha image are visible tow bright cones that extend up to 3 kpc along PA 32. The long slit spectra at PA 32 show that the velocity field of the gas in these regions is peculiar, while the ionization structure of the gas is similar to that of the NLR.

  11. Narrow-band photography of Jupiter and Saturn.

    NASA Technical Reports Server (NTRS)

    Fountain, J. W.

    1973-01-01

    An IR-sensitive vidicon was used in the 1 to 2 mu region, with narrow-bandwidth filters, for Jupiter photographs taken in April, 1971, and Saturn photographs taken in December, 1970. The changes in limb darkening and surface details observed at different wavelengths are discussed. The 37 Jupiter photographs and the 38 Saturn photographs are included.

  12. Ultrafast optical control of group delay of narrow-band terahertz waves

    PubMed Central

    Miyamaru, Fumiaki; Morita, Hiroki; Nishiyama, Yohei; Nishida, Tsubasa; Nakanishi, Toshihiro; Kitano, Masao; Takeda, Mitsuo W.

    2014-01-01

    We experimentally demonstrate control over the group delay of narrow-band (quasi continuous wave) terahertz (THz) pulses with constant amplitude based on optical switching of a metasurface characteristic. The near-field coupling between resonant modes of a complementary split ring resonator pair and a rectangular slit show an electromagnetically induced transparency-like (EIT-like) spectral shape in the reflection spectrum of a metasurface. This coupling induces group delay of a narrow-band THz pulse around the resonant frequency of the EIT-like spectrum. By irradiating the metasurface with an optical excitation pulse, the metasurface becomes mirror-like and thus the incident narrow-band THz pulse is reflected without a delay. Remarkably, if we select the appropriate excitation power, only the group delay of the narrow-band THz pulse can be switched while the amplitude is maintained before and after optical excitation. PMID:24614514

  13. Further improvements in program to calculate electronic properties of narrow band gap materials

    NASA Technical Reports Server (NTRS)

    Patterson, James D.

    1991-01-01

    Research into the properties of narrow band gap materials during the period 15 Jun. to 15 Dec. 1991 is discussed. Abstracts and bibliographies from papers presented during this period are reported. Graphs are provided.

  14. High-power narrow-vertical-divergence photonic band crystal laser diodes with optimized epitaxial structure

    SciTech Connect

    Liu, Lei; Qu, Hongwei; Liu, Yun; Zhang, Yejin; Zheng, Wanhua; Wang, Yufei; Qi, Aiyi

    2014-12-08

    900?nm longitudinal photonic band crystal (PBC) laser diodes with optimized epitaxial structure are fabricated. With a same calculated fundamental-mode divergence, stronger mode discrimination is achieved by a quasi-periodic index modulation in the PBC waveguide than a periodic one. Experiments show that the introduction of over 5.5??m-thick PBC waveguide contributes to only 10% increment of the internal loss for the laser diodes. For broad area PBC lasers, output powers of 5.75?W under continuous wave test and over 10?W under quasi-continuous wave test are reported. The vertical divergence angles are 10.5° at full width at half maximum and 21.3° with 95% power content, in conformity with the simulated angles. Such device shows a prospect for high-power narrow-vertical-divergence laser emission from single diode laser and laser bar.

  15. Narrow-band surveys for very high redshift Lyman-alpha emitters

    E-print Network

    Kim K. Nilsson; Alvaro Orsi; Cedric G. Lacey; Carlton M. Baugh; Eduard Thommes

    2007-09-03

    Context: Many current and future surveys aim to detect the highest redshift (z >~ 7) sources through their Lyman-alpha (Ly-alpha) emission, using the narrow-band imaging method. However, to date the surveys have only yielded non-detections and upper limits as no survey has reached the necessary combination of depth and area to detect these very young star forming galaxies. Aims: We aim to calculate model luminosity functions and mock surveys of Ly-alpha emitters at z >~ 7 based on a variety of approaches. Methods: We calculate model luminosity functions at different redshifts based on three different approaches: a semi-analytical model based on CDM, a simple phenomenological model, and an extrapolation of observed Schechter functions at lower redshifts. The results of the first two models are compared with observations made at redshifts z ~ 5.7 and z ~ 6.5, and they are then extrapolated to higher redshift. Results: We present model luminosity functions for redshifts between z = 7 - 12.5 and give specific number predictions for future planned or possible narrow-band surveys for Ly-alpha emitters. We also investigate what constraints future observations will be able to place on the Ly-alpha luminosity function at very high redshift. Conclusion: It should be possible to observe z = 7 - 10 Ly-alpha emitters with present or near-future instruments if enough observing time is allocated. In particular, large area surveys such as ELVIS (Emission Line galaxies with VISTA Survey) will be useful in collecting a large sample. However, to get a large enough sample to constrain well the z >= 10 Ly-alpha luminosity function, instruments further in the future, such as an ELT, will be necessary.

  16. ACS CCDs UV and Narrow-Band Filters Red Leak Check

    NASA Astrophysics Data System (ADS)

    Chiaberge, Marco; Sirianni, Marco

    2007-05-01

    We present results of the observations of the star 15 Mon, obtained with the aim of checking the impact of red leaks in the UV (and U-band) and two narrow-band filters on ACS CCDs. The red leak in the F220W, F250W and F330W filters appears to be smaller than measured in pre-flight tests. We derive updated passbands for the three filters and we present the updated correction table for different spectral types. The off-band flux in two narrow-band filters (F658N and F502N) is not measurable with the performed observations, thus we conclude that the red leak in narrow band filters is negligible.

  17. Large Format Narrow-Band, Multi-Band, and Broad-Band LWIR QWIP Focal Planes for Space and Earth Science Applications

    NASA Technical Reports Server (NTRS)

    Gunapala, S. D.; Bandara, S. V.

    2004-01-01

    A 640x512 pixel, long-wavelength cutoff, narrow-band (delta(lambda)/approx. 10%) quantum well infrared photodetector (QWIP) focal plane array (FPA), a four-band QWIP FPA in the 4-16 m spectral region, and a broad-band (delta(lambda)/approx. 42%) QWIP FPA having 15.4 m cutoff have been demonstrated.

  18. Nanoslit-microcavity-based narrow band absorber for sensing applications.

    PubMed

    Lu, Xiaoyuan; Zhang, Lingxuan; Zhang, Tongyi

    2015-08-10

    We propose an ultranarrow bandwidth perfect infrared absorber consisting of a metal periodic structured surface with nanoslits, a spacer dielectric, and a metal back plate. Its bandwidth and aborption are respectively about 8 nm and 95%. The thickness of the nanobars and the spacer, and the width of the nanoslits are primary factors determining the absorption performance. This structure not only has narrow bandwidth but also can obtain the giant electric field enhancement in the tiny volume of the nanoslits. Operated as a refractive index sensor, this structure has figure of merit as high as 25. It has potential in biomedical and sensing applications. PMID:26367923

  19. Narrow-band tunable laser system for a lidar facility

    NASA Astrophysics Data System (ADS)

    Panchenko, Yu. N.; Andreev, M. V.; Bobrovnikov, S. M.; Gorlov, E. V.; Dudarev, V. V.; Ivanov, N. G.; Losev, V. F.; Pavlinskii, A. V.; Puchikin, A. V.; Zharkov, V. I.

    2012-11-01

    A unique ultraviolet laser system has been developed for a lidar intended to detect nitrogen oxide molecules in the atmosphere. The electric-discharge KrF laser system is capable of producing a highly coherent laser beam with practically the same energy over a spectral range of 247.5-249.5 nm. At the edge of the amplification band in the range 247.5-247.8 nm, the system produces a beam of energy 0.3 J, pulse duration 16 ns, and spectral line width 2 pm. Atmospheric sounding by using this beam with an energy density of 200 mJ/cm2 in the scattered signal has detected noise in the 226 and 236 nm bands whose intensity increases the laser beam pulse repetition rate and energy density.

  20. Tracking photosynthetic efficiency with narrow-band spectroradiometry

    NASA Technical Reports Server (NTRS)

    Gamon, John A.; Field, Christopher B.

    1992-01-01

    Narrow-waveband spectroradiometry presents the possibility of detecting subtle signals closely related to the current physiological state of vegetation. One such signal related to the epoxidation state of the xanthophyll cycle pigments, violaxanthin, antheraxanthin, and zeaxanthin is discussed. Recent advances in plant ecophysiology demonstrated a close relationship between these pigments and the regulatory state of photosystem 2 in photosynthesis. Our recent field studies of sunflower (Helianthus annuus) and oak (Quercus agrifolia) demonstrated that a 'xanthophyll signal' can be isolated from the diurnal reflectance spectra of intact canopies. Furthermore, the xanthophyll signal can be used to derive a 'physiological reflectance index' (PRI) that closely correlates with the actual photosynthetic efficiency (defined as the photosynthetic rate divided by the incident PAR) in closed canopies. If these signals were detectable in Airborne Visible/Infrared Imaging Spectrometers (AVIRIS) images, they could lead to improved remote estimates of photosynthetic fluxes.

  1. Pilot-aided modulation for narrow-band satellite communications

    NASA Technical Reports Server (NTRS)

    Saulnier, Gary J.; Rafferty, William

    1988-01-01

    This paper discusses a number of tone-aided modulation techniques which have been studied as part of the Mobile Satellite Experiment (MSAT-X) Program. In all instances tone(s) are inserted into data-free portions of the transmit spectrum and used by the receiver to sense the amplitude and frequency/phase distortions introduced by the channel. The receiver then uses this information in a feedforward manner to lessen the effect of the distortions on the data detection performance. Particular techniques discussed are the Tone Calibration Technique (TCT), the Dual Tone Calibrated Technique (DTCT), Transparent Tone-In-Band (TTIB), and Dual-Tone Single Sideband (DTSSB).

  2. The relationship between rape biomass and narrow-band vegetation indices

    NASA Astrophysics Data System (ADS)

    Huang, Jingfeng; Wang, Yuan; Wang, Fumin; Wang, Xiuzhen

    2004-11-01

    The Relationships between rape biomass and hyperspectral vegetation indices are investigated in this paper. The data for this study comes from field hyperspectral reflectance measurements of rape during 2002-2003 growing period. Reflectance was measured in discrete narrow bands between 350 and 2500 nm. Observed rape biomass included wet biomass (WBM including leaf wet biomass-LWBM, stem wet biomass-SWBM, fruit wet biomass-FWBM), and dry biomass(DBM: including leaf dry biomass-LDBM, stem dry biomass, fruit dry biomass-FDBM). Narrow band normalized difference vegetation index (NBNDVI) and narrow band ratio vegetation index (NBRVI)involving all possible two-band combinations of discrete channels was tested. Special narrow band lambda (?1) versus lambda (?2) plots of R2 values illustrate the most effective wavelength combinations (?1 and ?2) and band-width (??1 and ??2) for predicting rape biomass at different development stage. A strong relationship with rape biomass is located in red-edge, the longer portion of red, moisture-sensitive NIR, longer portion of the blue band, the intermediate portion of SWIR, and the longer portion of SWIR.

  3. Band Gap Narrowing and Widening of ZnO Nanostructures and Doped Materials.

    PubMed

    Kamarulzaman, Norlida; Kasim, Muhd Firdaus; Rusdi, Roshidah

    2015-12-01

    Band gap change in doped ZnO is an observed phenomenon that is very interesting from the fundamental point of view. This work is focused on the preparation of pure and single phase nanostructured ZnO and Cu as well as Mn-doped ZnO for the purpose of understanding the mechanisms of band gap narrowing in the materials. ZnO, Zn0.99Cu0.01O and Zn0.99Mn0.01O materials were prepared using a wet chemistry method, and X-ray diffraction (XRD) results showed that all samples were pure and single phase. UV-visible spectroscopy showed that materials in the nanostructured state exhibit band gap widening with respect to their micron state while for the doped compounds exhibited band gap narrowing both in the nano and micron states with respect to the pure ZnO materials. The degree of band gap change was dependent on the doped elements and crystallite size. X-ray photoelectron spectroscopy (XPS) revealed that there were shifts in the valence bands. From both UV-visible and XPS spectroscopy, it was found that the mechanism for band gap narrowing was due to the shifting of the valance band maximum and conduction band minimum of the materials. The mechanisms were different for different samples depending on the type of dopant and dimensional length scales of the crystallites. PMID:26319225

  4. The Narrow-band Ultraviolet Imaging Experiment for Wide-field Surveys (NUVIEWS)-I: Dust scattered continuum

    E-print Network

    D. Schiminovich; P. Friedman; C. Martin; P. Morrissey

    1999-05-27

    We report on the first results of the Narrow-band Ultraviolet Imaging Experiment for Wide-field Surveys (NUVIEWS), a sounding rocket experiment designed to map the far-ultraviolet background in four narrow bands. This is the first imaging measurement of the UV background to cover a substantial fraction of the sky. The narrow band responses (145, 155, 161, and 174 nm, 7-10 nm wide) allow us to isolate background contributions from dust-scattered continuum, H2 fluorescence, and CIV 155 nm emission. In our first flight, we mapped one quarter of the sky with 5-10 arcminute imaging resolution. In this paper, we model the dominant contribution of the background, dust-scattered continuum. Our data base consists of a map of over 10,000 sq. degrees with 468 independent measurements in 6.25 by 6.25 sq. degree bins. Stars and instrumental stellar halos are removed from the data. We present a map of the continuum background obtained in the 174 nm telescope. We use a model that follows Witt, Friedman, and Sasseen (1997: WFS) to account for the inhomogeneous radiation field and multiple scattering effects in clouds. We find that the dust in the diffuse interstellar medium displays a moderate albedo (a=0.55+/-0.1) and highly forward scattering phase function parameter (g=0.75+/-0.1) over a large fraction of the sky, similar to dust in star forming regions. We also have discovered a significant variance from the model.

  5. Hydrogen-Saturated Saline Protects Intensive Narrow Band Noise-Induced Hearing Loss in Guinea Pigs through an Antioxidant Effect

    PubMed Central

    Chen, Liwei; Yu, Ning; Lu, Yan; Wu, Longjun; Chen, Daishi; Guo, Weiwei; Zhao, Lidong; Liu, Mingbo; Yang, Shiming; Sun, Xuejun; Zhai, Suoqiang

    2014-01-01

    The purpose of the current study was to evaluate hydrogen-saturated saline protecting intensive narrow band noise-induced hearing loss. Guinea pigs were divided into three groups: hydrogen-saturated saline; normal saline; and control. For saline administration, the guinea pigs were given daily abdominal injections (1 ml/100 g) 3 days before and 1 h before narrow band noise exposure (2.5–3.5 kHz 130 dB SPL, 1 h). The guinea pigs in the control group received no treatment. The hearing function was assessed by the auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) recording. The changes of free radicals in the cochlea before noise exposure, and immediately and 7 days after noise exposure were also examined. By Scanning electron microscopy and succinate dehydrogenase staining, we found that pre-treatment with hydrogen-saturated saline significantly reduced noise-induced hair cell damage and hearing loss. We also found that the malondialdehyde, lipid peroxidation, and hydroxyl levels were significantly lower in the hydrogen-saturated saline group after noise trauma, indicating that hydrogen-saturated saline can decrease the amount of harmful free radicals caused by noise trauma. Our findings suggest that hydrogen-saturated saline is effective in preventing intensive narrow band noise-induced hearing loss through the antioxidant effect. PMID:24945316

  6. Suppression of the unwanted variations in data. [in geophysical research by narrow-band delay filters

    NASA Technical Reports Server (NTRS)

    Bernhardt, P. A.; Schlapp, D. M.

    1976-01-01

    The removal of unwanted frequency components in geophysical data may be accomplished by filtering. The filtering procedure described in this paper consists of estimating the undesirable component by using a narrow-band delay filter and subtracting the estimate from the data. Suppression of strong solar components in the presence of weak lunar components is considered in detail.

  7. Reverberation decay functions for narrow bands obtained from filtered time-windowed room impulse responses (L).

    PubMed

    Mo, Fangshuo

    2015-06-01

    This study introduces a method to obtain the reverberation decay functions for narrow bands from the filtered time-windowed broadband room impulse responses. The method corresponds to the free decay process of the band-pass sound energy. The filtering process is independent of the band-pass filter phase responses and it reduces the filtering influence on the decay rates. It places no limit on the permissible product BT of the bandwidth B and the reverberation time T when evaluating the decay rates of the obtained decay functions. PMID:26093442

  8. The design and fabricate of wide angle 905nm narrow band filter

    NASA Astrophysics Data System (ADS)

    Shi, Baohua; Li, Zaijin; Li, Hongyu; Qu, Yi

    2014-12-01

    All-dielectric film narrow band filter is widely used in laser system owing to its excellent optical capability, manufacturability and environmental adaptability. But 905nm infrared semiconductor laser system have large divergence angel so we designed entrance light cone angle 905nm narrow band filter. And center wavelength shift, due to entrance light cone angle, affects its spectral selective power seriously. In order to reduce these impacts, an informal dielectric film narrowband filter is designed. Changes of transmission characteristics with oblique incidence of Gaussian beam of uneven illumination are analyzed. The relationship between the angle of incidence and the central wavelength shift quantificational are Solved. A ± 30 ° incident 905nm narrowband filter was fabricated. Between 880nm and 950nm, the average transmittance is above 90%, and at the cut-off band the average transmittance is below 1%.

  9. Fitting narrow-band models to temperature-dependent, spectral absorption coefficients of fuel vapors

    NASA Astrophysics Data System (ADS)

    Lecoustre, V. R.; Wakatsuki, K.; Jackson, G. S.

    2014-11-01

    Accurate modeling of infrared radiation transport through fuel rich cores of fires and other non-premixed combustion processes requires computationally efficient processing of temperature-dependent, spectral absorption coefficients for major fuel vapor species. Spectrally resolved transmissivity band measurements in the mid-infrared and near-infrared have been taken in recent years for numerous small fuel molecules including but not limited to ethane, ethylene, and propylene for a range of temperatures relevant for combustion environments. This paper compares the spectral transmissivity measurements using FTIR for both ethane and ethylene with the HITRAN 2012 edition. Narrow band absorption coefficients and overlap parameters are derived by fitting the spectral transmissivity measurements for ethane, ethylene, and propylene with narrow band models for temperatures up to 1000 K. The resulting fits provide a basis for calculating spectrally resolved infrared radiation transport in fuel rich cores of flames and other combustion processes where these species can be prevalent.

  10. An Interpretation of Banded Magnetospheric Radio Emissions

    NASA Technical Reports Server (NTRS)

    Benson, Robert F.; Osherovich, V. A.; Fainberg, J.; Vinas, A. F.; Ruppert, D. R.; Vondrak, Richard R. (Technical Monitor)

    2000-01-01

    Recently-published Active Magnetospheric Particle Tracer Explorer/Isothermal Remanent Magnetization (AMPTE/IRM) banded magnetospheric emissions, commonly referred to as '(n + 1/2)f(sub ce)' emissions where f(sub ce) is the electron gyrofrequency, are analyzed by treating them as analogous to sounder-stimulated ionospheric emissions. We show that both individual AMPTE/IRM spectra of magnetospheric banded emissions, and a statistically-derived spectra observed over the two-year lifetime of the mission, can be interpreted in a self-consistent manner. The analysis, which predicts all spectral peaks within 4% of the observed peaks, interprets the higher-frequency emissions as due to low group-velocity Bernstein-mode waves and the lower-frequency emissions as eigen modes of cylindrical-electromagnetic-plasma-oscillations. The demarcation between these two classes of emissions is the electron plasma frequency f(sub pe), where an emission is often observed. This f(sub pe), emission is not necessarily the strongest. None of the observed banded emissions were attributed to the upper-hybrid frequency. We present Alouette-2 and ISIS-1 plasma-resonance data, and model electron temperature (T(sub e)) values, to support the argument that the frequency-spectrum of ionospheric sounder-stimulated emissions is not strongly temperature dependent and thus that the interpretation of these emissions in the ionosphere is relevant to other plasmas (such as the magnetosphere) where N(sub e) and T(sub e) can be quite different but where the ratio f(sub pe)/f(sub ce) is identical.

  11. Line shapes of narrow optical bands: Infrared absorption by U centers and heavier impurities in alkali halides

    NASA Astrophysics Data System (ADS)

    Lagos, Miguel; Asenjo, Felipe; Hauyón, Roberto; Pastén, Denisse; González, Hernán; Henríquez, Ricardo; Troncoso, Roberto

    2008-03-01

    The shape of the bands for photon absorption and emission by the local constituents of a solid is governed mainly by processes involving many low-energy acoustic phonons. This applies not only to wide bands, such as those exhibited by F centers, but also to narrow ones, as those observed for infrared absorption by local vibration modes of U centers and heavier impurities. The line shapes are theoretically studied on a general basis to show they provide a nice example to illustrate the power of field theory and methods to reproduce experimental facts. To this aim, the phonon induced broadenings of infrared absorption lines by U centers in KCl and KBr, and by substitutional Ag+ in KI, were calculated to compare theoretical predictions with experiment. The agreement obtained between both is remarkable.

  12. Highly efficient narrow-band green and red phosphors enabling wider color-gamut LED backlight for more brilliant displays.

    PubMed

    Wang, Le; Wang, Xiaojun; Kohsei, Takahashi; Yoshimura, Ken-Ichi; Izumi, Makoto; Hirosaki, Naoto; Xie, Rong-Jun

    2015-11-01

    In this contribution, we propose to combine both narrow-band green (?-sialon:Eu2+) and red (K2SiF6:Mn4+) phosphors with a blue InGaN chip to achieve white light-emitting diodes (wLEDs) with a large color gamut and a high efficiency for use as the liquid crystal display (LCD) backlighting. ?-sialon:Eu2+, prepared by a gas-pressure sinteing technique, has a peak emission at 535 nm, a full width at half maximum (FWHM) of 54 nm, and an external quantum efficiency of 54.0% under the 450 nm excitation. K2SiF6:Mn4+ was synthesized by a twe-step co-precipitation methods, and exhibits a sharp line emission spectrum with the most intensified peak at 631 nm, a FWHM of ~3 nm, and an external quantum efficiency of 54.5%. The prepared three-band wLEDs have a high color temperature of 11,184 - 13,769 K (i.e., 7,828 - 8,611 K for LCD displays), and a luminous efficacy of 91 - 96 lm/W, measured under an applied current of 120 mA. The color gamut defined in the CIE 1931 and CIE 1976 color spaces are 85.5 - 85.9% and 94.3 - 96.2% of the NTSC stanadard, respectively. These optical properties are better than those phosphor-cpnverted wLED backlights using wide-band green or red phosphoprs, suggesting that the two narrow-band phosphors investigated are the most suitable luminescent materials for achieving more bright and vivid displays. PMID:26561139

  13. Landau Damping and Coherent Structures in Narrow-Banded 1+1 Deep Water Gravity Waves

    E-print Network

    M. Onorato; A. Osborne; M. Serio; R. Fedele

    2002-02-12

    We study the nonlinear energy transfer around the peak of the spectrum of surface gravity waves by taking into account nonhomogeneous effects. In the narrow-banded approximation the kinetic equation resulting from a nonhomogeneous wave field is a Vlasov-Poisson type equation which includes at the same time the random version of the Benjamin-Feir instability and the Landau damping phenomenon. We analytically derive the values of the Phillips' constant $\\alpha$ and the enhancement factor $\\gamma$ for which the narrow-banded approximation of the JONSWAP spectrum is unstable. By performing numerical simulations of the nonlinear Schr\\"{o}dinger equation we check the validity of the prediction of the related kinetic equation. We find that the effect of Landau damping is to suppress the formation of coherent structures. The problem of predicting freak waves is briefly discussed.

  14. On a Hydrodynamic Source of Self-Excitation of Narrow-Band Disturbances in a Wind Tunnel

    NASA Astrophysics Data System (ADS)

    Karavosov, R. K.; Prozorov, A. G.

    2014-11-01

    A study has been made of the occurrence of intense narrow-band components in the spectra of pressure pulsations in a wind tunnel. It has been established that the high level of acoustic emission in auto-oscillations is a consequence of negative static-pressure gradients inside the nozzle and the change in the regime of wall shear flow of an incompressible medium, of the formation of large-scale coherent structures, and of resonance phenomena. It has been noted that the azimuthally nonuniform topology of large-scale transient-flow structures emitting sound and implementation of not a single resonance are responsible for the existence of ensembles of components of an undesirably high level in the pressure-pulsation spectra in the tunnel. One possible method of fighting the considered sound emission generating auto-oscillations has been indicated.

  15. A theory for narrow-banded radio bursts at Uranus - MHD surface waves as an energy driver

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Curtis, S. A.; Desch, M. D.; Lepping, R. P.

    1992-01-01

    A possible scenario for the generation of the narrow-banded radio bursts detected at Uranus by the Voyager 2 planetary radio astronomy experiment is described. In order to account for the emission burstiness which occurs on time scales of hundreds of milliseconds, it is proposed that ULF magnetic surface turbulence generated at the frontside magnetopause propagates down the open/closed field line boundary and mode-converts to kinetic Alfven waves (KAW) deep within the polar cusp. The oscillating KAW potentials then drive a transient electron stream that creates the bursty radio emission. To substantiate these ideas, Voyager 2 magnetometer measurements of enhanced ULF magnetic activity at the frontside magnetopause are shown. It is demonstrated analytically that such magnetic turbulence should mode-convert deep in the cusp at a radial distance of 3 RU.

  16. Advanced Imaging Technology in Biliary Tract Diseases:Narrow-Band Imaging of the Bile Duct

    PubMed Central

    Choi, Hyun Jong; Moon, Jong Ho; Lee, Yun Nah

    2015-01-01

    Newly introduced direct peroral cholangioscopy and the development of video choledochoscopes have enabled more defined observation of bile duct mucosal lesions with clearer images. Narrow-band imaging (NBI) is a unique endoscopic imaging technology that provides enhanced endoscopic images of surface mucosal structures and its superficial microvessels. Advanced cholangioscopy and NBI are expected to be useful for precise evaluation and correct diagnosis of biliary tract diseases. However, the diagnostic value of advanced bile duct imaging with cholangioscopy requires further evaluation.

  17. Narrow-band radiation wavelength measurement by processing digital photographs in RAW format

    SciTech Connect

    Kraiskii, A V; Mironova, T V; Sultanov, T T

    2012-12-31

    The technique of measuring the mean wavelength of narrow-band radiation in the 455 - 625-nm range using the image of the emitting surface is presented. The data from the camera array unprocessed by the built-in processor (RAW format) are used. The method is applied for determining the parameters of response of holographic sensors. Depending on the wavelength and brightness of the image fragment, the mean square deviation of the wavelength amounts to 0.3 - 3 nm. (experimental techniques)

  18. Band gap narrowing in BaTiO{sub 3} nanoparticles facilitated by multiple mechanisms

    SciTech Connect

    Ramakanth, S.; James Raju, K. C.

    2014-05-07

    In the present work, BaTiO{sub 3} nanoparticles of four different size ranges were prepared by sol-gel method. The optical band gap of these particles at some size ranges has come down to 2.53?eV from 3.2?eV, resulting in substantial increase in optical absorption by these ferroelectric nanoparticles making them potential candidates for light energy harvesting. XRD results show the presence of higher compressive strain in 23?nm and 54?nm size particles, they exhibit a higher band gap narrowing, whereas tensile strain is observed in 31?nm and 34?nm particles, and they do not show the marginal band gap narrowing. The 23?nm and 54?nm particles also show a coupling of free carriers to phonons by increasing the intensity of LO phonon mode at 715?cm{sup ?1}. The higher surface charge density is expected in case of enhanced surface optical Raman modes (638?cm{sup ?1}) contained in 31 and 34?nm size particles. In addition to this, the red shift in an LO mode Raman spectral line at 305?cm{sup ?1} with decrease in particle size depicts the presence of phonon confinement in it. The enhanced optical absorption in 23?nm and 54?nm size particles with a narrowed band gap of 3?eV and 2.53?eV is due to exchange correlation interactions between the carriers present in these particles. In 31?nm and 34?nm range particles, the absorption got bleached exhibiting increased band gaps of 3.08?eV and 3.2?eV, respectively. It is due to filling up of conduction band resulting from weakening of exchange correlation interactions between the charge carriers. Hence, it is concluded that the band gap narrowing in the nanoparticles of average size 23?nm/54?nm is a consequence of multiple effects like strain, electron-phonon interaction, and exchange correlation interactions between the carriers which is subdued in some other size ranges like 31?nm/34?nm.

  19. UNIDENTIFIED INFRARED EMISSION BANDS: PAHs or MAONs?

    SciTech Connect

    Sun Kwok; Yong Zhang

    2013-07-01

    We suggest that the carrier of the unidentified infrared emission (UIE) bands is an amorphous carbonaceous solid with mixed aromatic/aliphatic structures, rather than free-flying polycyclic aromatic hydrocarbon molecules. Through spectral fittings of the astronomical spectra of the UIE bands, we show that a significant amount of the energy is emitted by the aliphatic component, implying that aliphatic groups are an essential part of the chemical structure. Arguments in favor of an amorphous, solid-state structure rather than a gas-phase molecule as a carrier of the UIE are also presented.

  20. Narrow-band search of continuous gravitational-wave signals from Crab and Vela pulsars in Virgo VSR4 data

    E-print Network

    The LIGO Scientific Collaboration; the Virgo Collaboration; J. Aasi; B. P. Abbott; R. Abbott; T. Abbott; M. R. Abernathy; F. Acernese; K. Ackley; C. Adams; T. Adams; T. Adams; P. Addesso; R. X. Adhikari; V. Adya; C. Affeldt; M. Agathos; K. Agatsuma; N. Aggarwal; O. D. Aguiar; A. Ain; P. Ajith; A. Alemic; B. Allen; A. Allocca; D. Amariutei; S. B. Anderson; W. G. Anderson; K. Arai; M. C. Araya; C. Arceneaux; J. S. Areeda; G. Ashton; S. Ast; S. M. Aston; P. Astone; P. Aufmuth; C. Aulbert; B. E. Aylott; S. Babak; P. T. Baker; F. Baldaccini; G. Ballardin; S. W. Ballmer; J. C. Barayoga; M. Barbet; S. Barclay; B. C. Barish; D. Barker; F. Barone; B. Barr; L. Barsotti; M. Barsuglia; J. Bartlett; M. A. Barton; I. Bartos; R. Bassiri; A. Basti; J. C. Batch; Th. S. Bauer; C. Baune; V. Bavigadda; B. Behnke; M. Bejger; C. Belczynski; A. S. Bell; C. Bell; M. Benacquista; J. Bergman; G. Bergmann; C. P. L. Berry; D. Bersanetti; A. Bertolini; J. Betzwieser; S. Bhagwat; R. Bhandare; I. A. Bilenko; G. Billingsley; J. Birch; S. Biscans; M. Bitossi; C. Biwer; M. A. Bizouard; J. K. Blackburn; L. Blackburn; C. D. Blair; D. Blair; S. Bloemen; O. Bock; T. P. Bodiya; M. Boer; G. Bogaert; P. Bojtos; C. Bond; F. Bondu; L. Bonelli; R. Bonnand; R. Bork; M. Born; V. Boschi; Sukanta Bose; C. Bradaschia; P. R. Brady; V. B. Braginsky; M. Branchesi; J. E. Brau; T. Briant; D. O. Bridges; A. Brillet; M. Brinkmann; V. Brisson; A. F. Brooks; D. A. Brown; D. D. Brown; N. M. Brown; S. Buchman; A. Buikema; T. Bulik; H. J. Bulten; A. Buonanno; D. Buskulic; C. Buy; L. Cadonati; G. Cagnoli; J. Calderón Bustillo; E. Calloni; J. B. Camp; K. C. Cannon; J. Cao; C. D. Capano; F. Carbognani; S. Caride; S. Caudill; M. Cavaglià; F. Cavalier; R. Cavalieri; G. Cella; C. Cepeda; E. Cesarini; R. Chakraborty; T. Chalermsongsak; S. J. Chamberlin; S. Chao; P. Charlton; E. Chassande-Mottin; Y. Chen; A. Chincarini; A. Chiummo; H. S. Cho; M. Cho; J. H. Chow; N. Christensen; Q. Chu; S. Chua; S. Chung; G. Ciani; F. Clara; J. A. Clark; F. Cleva; E. Coccia; P. -F. Cohadon; A. Colla; C. Collette; M. Colombini; L. Cominsky; M. Constancio, Jr.; A. Conte; D. Cook; T. R. Corbitt; N. Cornish; A. Corsi; C. A. Costa; M. W. Coughlin; J. -P. Coulon; S. Countryman; P. Couvares; D. M. Coward; M. J. Cowart; D. C. Coyne; R. Coyne; K. Craig; J. D. E. Creighton; T. D. Creighton; J. Cripe; S. G. Crowder; A. Cumming; L. Cunningham; E. Cuoco; C. Cutler; K. Dahl; T. Dal Canton; M. Damjanic; S. L. Danilishin; S. D'Antonio; K. Danzmann; L. Dartez; V. Dattilo; I. Dave; H. Daveloza; M. Davier; G. S. Davies; E. J. Daw; R. Day; D. DeBra; G. Debreczeni; J. Degallaix; M. De Laurentis; S. Deléglise; W. Del Pozzo; T. Denker; T. Dent; H. Dereli; V. Dergachev; R. De Rosa; R. T. DeRosa; R. DeSalvo; S. Dhurandhar; M. Díaz; L. Di Fiore; A. Di Lieto; I. Di Palma; A. Di Virgilio; G. Dojcinoski; V. Dolique; E. Dominguez; F. Donovan; K. L. Dooley; S. Doravari; R. Douglas; T. P. Downes; M. Drago; J. C. Driggers; Z. Du; M. Ducrot; S. Dwyer; T. Eberle; T. Edo; M. Edwards; M. Edwards; A. Effler; H. -B. Eggenstein; P. Ehrens; J. Eichholz; S. S. Eikenberry; R. Essick; T. Etzel; M. Evans; T. Evans; M. Factourovich; V. Fafone; S. Fairhurst; X. Fan; Q. Fang; S. Farinon; B. Farr; W. M. Farr; M. Favata; M. Fays; H. Fehrmann; M. M. Fejer; D. Feldbaum; I. Ferrante; E. C. Ferreira; F. Ferrini; F. Fidecaro; I. Fiori; R. P. Fisher; R. Flaminio; J. -D. Fournier; S. Franco; S. Frasca; F. Frasconi; Z. Frei; A. Freise; R. Frey; T. T. Fricke; P. Fritschel; V. V. Frolov; S. Fuentes-Tapia; P. Fulda; M. Fyffe; J. R. Gair; L. Gammaitoni; S. Gaonkar; F. Garufi; A. Gatto; N. Gehrels; G. Gemme; B. Gendre; E. Genin; A. Gennai; L. Á. Gergely; S. Ghosh; J. A. Giaime; K. D. Giardina; A. Giazotto; J. Gleason; E. Goetz; R. Goetz; L. Gondan; G. González; N. Gordon; M. L. Gorodetsky; S. Gossan; S. Goßler; R. Gouaty; C. Gräf; P. B. Graff; M. Granata; A. Grant; S. Gras; C. Gray; G. Greco; R. J. S. Greenhalgh; A. M. Gretarsson; P. Groot; H. Grote; S. Grunewald; G. M. Guidi; C. J. Guido; X. Guo; K. Gushwa; E. K. Gustafson; R. Gustafson; J. Hacker; E. D. Hall; G. Hammond; M. Hanke; J. Hanks; C. Hanna; M. D. Hannam; J. Hanson; T. Hardwick; J. Harms; G. M. Harry; I. W. Harry; M. Hart; M. T. Hartman; C. -J. Haster; K. Haughian; S. Hee; A. Heidmann; M. Heintze; G. Heinzel; H. Heitmann; P. Hello; G. Hemming; M. Hendry; I. S. Heng; A. W. Heptonstall; M. Heurs; M. Hewitson; S. Hild; D. Hoak; K. A. Hodge; D. Hofman; S. E. Hollitt; K. Holt; P. Hopkins; D. J. Hosken; J. Hough; E. Houston; E. J. Howell; Y. M. Hu; E. Huerta; B. Hughey; S. Husa; S. H. Huttner; M. Huynh; T. Huynh-Dinh; A. Idrisy; N. Indik; D. R. Ingram; R. Inta; G. Islas; J. C. Isler; T. Isogai; B. R. Iyer; K. Izumi; M. Jacobson; H. Jang; P. Jaranowski; S. Jawahar; Y. Ji; F. Jiménez-Forteza; W. W. Johnson; D. I. Jones; R. Jones; R. J. G. Jonker; L. Ju; Haris K

    2014-10-30

    In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small mismatch between the gravitational wave frequency and two times the star rotation frequency, inferred from measurement of the electromagnetic pulse rate, a range of 0.02 Hz around two times the star rotational frequency has been searched for both the pulsars. No evidence for a signal has been found and 95$\\%$ confidence level upper limits have been computed both assuming polarization parameters are completely unknown and that they are known with some uncertainty, as derived from X-ray observations of the pulsar wind torii. For Vela the upper limits are comparable to the spin-down limit, computed assuming that all the observed spin-down is due to the emission of gravitational waves. For Crab the upper limits are about a factor of two below the spin-down limit, and represent a significant improvement with respect to past analysis. This is the first time the spin-down limit is significantly overcome in a narrow-band search.

  1. Narrow-band search of continuous gravitational-wave signals from Crab and Vela pulsars in Virgo VSR4 data

    NASA Astrophysics Data System (ADS)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J. S.; Ashton, G.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barclay, S.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Bartlett, J.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bauer, Th. S.; Baune, C.; Bavigadda, V.; Behnke, B.; Bejger, M.; Belczynski, C.; Bell, A. S.; Bell, C.; Benacquista, M.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackburn, L.; Blair, C. D.; Blair, D.; Bloemen, S.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogaert, G.; Bojtos, P.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, Sukanta; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brau, J. E.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchman, S.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Carbognani, F.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C.; Colombini, M.; Cominsky, L.; Constancio, M.; Conte, A.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Cutler, C.; Dahl, K.; Canton, T. Dal; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dartez, L.; Dattilo, V.; Dave, I.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Dojcinoski, G.; Dolique, V.; Dominguez, E.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Drago, M.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Edwards, M.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, X.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fisher, R. P.; Flaminio, R.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fuentes-Tapia, S.; Fulda, P.; Fyffe, M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S.; Garufi, F.; Gatto, A.; Gehrels, N.; Gemme, G.; Gendre, B.; Genin, E.; Gennai, A.; Gergely, L. Á.; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Gräf, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guido, C. J.; Guo, X.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hacker, J.; Hall, E. D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Hee, S.; Heidmann, A.; Heintze, M.; Heinzel, G.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hofman, D.; Hollitt, S. E.; Holt, K.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E.

    2015-01-01

    In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small mismatch between the gravitational-wave frequency and two times the star rotation frequency, inferred from measurement of the electromagnetic pulse rate, a range of 0.02 Hz around two times the star rotational frequency has been searched for both the pulsars. No evidence for a signal has been found and 95% confidence level upper limits have been computed assuming both that polarization parameters are completely unknown and that they are known with some uncertainty, as derived from x-ray observations of the pulsar wind torii. For Vela the upper limits are comparable to the spin-down limit, computed assuming that all the observed spin-down is due to the emission of gravitational waves. For Crab the upper limits are about a factor of 2 below the spin-down limit, and represent a significant improvement with respect to past analysis. This is the first time the spin-down limit is significantly overcome in a narrow-band search.

  2. Narrow-Band Search of Continuous Gravitational-Wave Signals from Crab and Vela Pulsars in Virgo VSR4 Data

    NASA Technical Reports Server (NTRS)

    Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Allocca, A.; Amariutei, D.; Camp, J. B.; Gehrels, N.

    2014-01-01

    In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small mismatch between the gravitational wave frequency and two times the star rotation frequency, inferred from measurement of the electromagnetic pulse rate, a range of 0.02 Hz around two times the star rotational frequency has been searched for both the pulsars. No evidence for a signal has been found and 95% confidence level upper limits have been computed both assuming polarization parameters are completely unknown and that they are known with some uncertainty, as derived from X-ray observations of the pulsar wind torii. For Vela the upper limits are comparable to the spin-down limit, computed assuming that all the observed spin-down is due to the emission of gravitational waves. For Crab the upper limits are about a factor of two below the spin-down limit, and represent a significant improvement with respect to past analysis. This is the first time the spin-down limit is significantly overcome in a narrow-band search.

  3. Some observations about the components of transonic fan noise from narrow-band spectral analysis

    NASA Technical Reports Server (NTRS)

    Saule, A. V.

    1974-01-01

    Qualitative and quantitative spectral analyses are presented that give the broadband-noise, discrete-tone, and multiple-tone properties of the noise generated by a full-scale high-bypass single-stage axial-flow transonic fan (fan B, NASA Quiet Engine Program). The noise components were obtained from narrow-band spectra in conjunction with 1/3-octave-band spectra. Variations in the pressure levels of the noise components with fan speed, forward-quadrant azimuth angle, and frequency are presented and compared. The study shows that much of the apparent broadband noise on 1/3-octave-band plots consists of a complex system of shaft-order tones. The analyses also indicate the difficulties in determining or defining noise components, especially the broadband level under the discrete tones. The sources which may be associated with the noise components are discussed.

  4. Diffuse Interstellar Band Emission in the Galaxy

    NASA Astrophysics Data System (ADS)

    Burton Williams, Theodore; Sarre, Peter; Marshall, Charlotte; Spekkens, Kristine; Kuzio de Naray, Rachel

    2015-08-01

    The longest-standing problem in astronomical spectroscopy is the identification of the carriers of the diffuse interstellar absorption bands (DIBs), the first examples of which were discovered on photographic plates almost 100 years ago. Most researchers consider a population of large carbon-based molecules to be responsible for the DIBs. Identification of the carriers would open a new probe of interstellar conditions and processes in interstellar clouds and could have implications far beyond - including the role of such molecules in star and planet formation and even for the origins of life. Only one clear-cut example exists where complementary emission (from a subset) of DIBs is seen - in the Red Rectangle nebula - where the emission is excited by radiation from the central star HD 44179.Recent Fabry-Perot observations towards galaxy NGC 1325 with the Southern African Large Telescope led to the serendipitous discovery of an emission feature centered at 6613 Å arising from material in the ISM of our Galaxy; this emission feature lies at the wavelength of one of the sharper and stronger diffuse bands normally seen in absorption, and it is one of the most prominent of the Red Rectangle emission bands. The flux of the feature is 4.2 ± 0.5 x 10-18 e/s/cm2 /arc-sec2. It appears that this is the first observation of emission from a diffuse band carrier in the ISM, excited in this case by the interstellar radiation field. Unlike the Red Rectangle, the emission from the ISM is expected to have a very low molecular rotational temperature, potentially as low as 3 K. Spectra of this nature will assist greatly in spectroscopic analysis and in refining the nature of the molecules responsible for the DIB spectrum.We present the discovery spectra and follow-up measurements for the expected strong DIB features at 6613, 5797, 5850 and 5418 Å, in fields near NGC 1325, near the Red Rectangle, and near Rho Ophiuchi.

  5. The Unidentified Infrared Emission Bands: Identified

    NASA Technical Reports Server (NTRS)

    Hudgins, Douglas M.; Allamandola, Louis J.; Sandford, Scott A.; Goorvitch, David (Technical Monitor)

    1998-01-01

    The so-called Unidentified Infrared or simply UIR bands, the infrared emission band spectrum associated with a wide variety of interstellar objects, can be modeled in detail by laboratory spectra of neutral and positively charged polycyclic aromatic hydrocarbon (PAH) mixtures. Fits are presented for the UIR emission from the protoplanetary nebula IRAS 22272+5435, the diffuse galactic medium, and the Orion HII/photodissociation front - a selection of objects which span the evolutionary range of interstellar material. These data directly address the spectroscopic criticisms previously leveled at the PAH hypothesis and demonstrate that PAH-related molecular species are indeed responsible for this widespread emission. Furthermore, these fits reflect the structure, abundance, and ionization state of the interstellar PAHs and, in turn, provide direct insight into the processes of carbon nucleation, growth and evolution in circumstellar shells and the interstellar medium. To date, no other candidate material which has been proposed to account for the UIR emission can as readily and specifically reproduce these spectral variations. Given the ubiquity of these species, this work demonstrates the tremendous potential of these species as probes of a new and heretofore largely unexplored facet of astrochemistry - potential which should make PAHs the probe of the next millennium much as CO has been for the last quarter century.

  6. Encircling Narrow Band versus Buckle for Retinal Detachments with Intrabasal or Unseen Retinal Breaks

    PubMed Central

    Banaee, Touka; Hosseini, Seyedeh Maryam; Helmi, Toktam; Ghooshkhanei, Haleh

    2015-01-01

    Purpose: To compare the results of narrow encircling band surgery with standard encircling scleral buckling for retinal detachments (RDs) with intrabasal or unseen breaks. Methods: In a retrospective study, eyes with intrabasal or unseen breaks underwent narrow band implantation (group N) or standard encircling buckling plus wide tire placement (group W) and were followed for at least one year. Results: A total of 112 eyes including 39 eyes in group N and 73 eyes in group W were studied. Preoperatively visual acuity of eyes in group N was significantly better (1.55 ± 0.9 vs. 1.93 ± 0.9 logMAR, P = 0.043). The two study groups (N and W) were comparable in terms of the extent of RD (2.8 ± 0.96 vs. 2.8 ± 0.93 quadrants), interval to surgery (88.3 ± 176.4 vs. 71.9 ± 135.4 days) and percentage of visible breaks (56.4% vs. 63%), respectively (all P values > 0.05). More atrophic holes were present in group W and more dialyses were reported in group N. The single operation success rate at 12 months was 69.2% in group N and 74% in group W (P = 0.1). The single operation success rate for eyes with unseen breaks was also comparable (66.7% vs. 85.7%, P = 0.157). Final corrected visual acuity was also similar (0.63 ± 0.44 vs. 0.85 ± 0.69 log MAR). The only factor influencing success rate was the type of retinal breaks (P = 0.04). Type of scleral buckling did not affect the single operation success rate (P = 0.460). Conclusion: Narrow encircling band surgery is a possible option with acceptable single operation success rate for RDs with intrabasal or unseen breaks. PMID:26005554

  7. A comparison between weighted sum of gray gases and statistical narrow-band radiation models for combustion applications

    SciTech Connect

    Soufiani, A. . Lab. d'Energetique Moleculaire et Macroscopique); Djavdan, E. )

    1994-05-01

    The weighted sum of gray gases (WSGG) and the statistical narrow-band (SNB) models are implemented for radiative transfer calculations in realistic combustion gas mixtures and their results are compared. The WSGG model parameters are generated from SNB emissivity calculations in the [300, 2500 K] temperature range for a partial pressure ratio p[sub w]/p[sub c] = 2. In addition, the same methods are used for the resolution of the transfer equation associated with both models. Comparisons are made for the cases of planar geometry and an axisymmetrical methane--oxygen furnace. When the gas mixture is practically isothermal and surrounded by cold walls, small errors are introduced by the use of the WSGG model. On the other hand, in the case of significant temperature gradients, the inaccurate representation of gas absorptivities by the WSGG model leads to important errors.

  8. Narrow-band plasmonic directional excitation of two metallic slits with a coupled cavity.

    PubMed

    Wang, Yueke; Chen, Quansheng; Wu, Xinyu

    2015-09-20

    We investigate theoretically and numerically a model that can achieve narrow-band plasmonic directional excitation in the near-infrared region. The structure is a silver film modified by two uniform metallic slits with a coupled cavity. Our design method is based on the coupled cavity theory, and surface plasmon polaritons (SPPs) interference. The work wavelength region is chosen when the coupled cavity is in resonance. The distance between the two slits is chosen based on SPPs interference. The directional excitation bandwidth can be only 37.9 nm. The finite-difference time-domain method is carried to verify our design method. PMID:26406518

  9. Generation of Narrow-Band Polarization-Entangled Photon Pairs for Atomic Quantum Memories

    E-print Network

    Xiao-Hui Bao; Yong Qian; Jian Yang; Han Zhang; Zeng-Bing Chen; Tao Yang; Jian-Wei Pan

    2008-11-03

    We report an experimental realization of a narrow-band polarization-entangled photon source with a linewidth of 9.6 MHz through cavity-enhanced spontaneous parametric down-conversion. This linewidth is comparable to the typical linewidth of atomic ensemble based quantum memories. Single-mode output is realized by setting a reasonable cavity length difference between different polarizations, using of temperature controlled etalons and actively stabilizing the cavity. The entangled property is characterized with quantum state tomography, giving a fidelity of 94% between our state and a maximally entangled state. The coherence length is directly measured to be 32 m through two-photon interference.

  10. A simplified scheme for generating narrow-band mid-ultraviolet laser radiation

    SciTech Connect

    Almog, G.; Scholz, M. Weber, W.; Leisching, P.; Kaenders, W.; Udem, Th.

    2015-03-15

    We report on the development and characterization of continuous, narrow-band, and tunable laser systems that use direct second-harmonic generation from blue and green diode lasers with an output power level of up to 11.1 mW in the mid-ultraviolet. One of our laser systems was tuned to the mercury 6{sup 1}S{sub 0} ? 6{sup 3}P{sub 1} intercombination line at 253.7 nm. We could perform Doppler-free saturation spectroscopy on this line and were able to lock our laser to the transition frequency on long time scales.

  11. Landau damping and coherent structures in narrow-banded 1+1 deep water gravity waves.

    PubMed

    Onorato, Miguel; Osborne, Alfred; Fedele, Renato; Serio, Marina

    2003-04-01

    We study the modulational instability in surface gravity waves with random phase spectra. Starting from the nonlinear Schrödinger equation and using the Wigner-Moyal transform, we study the stability of the narrow-banded approximation of a typical wind-wave spectrum, i.e., the JONSWAP spectrum. By performing numerical simulations of the nonlinear Schrödinger equation we show that in the unstable regime, the nonlinear stage of the modulational instability is responsible for the formation of coherent structures. Furthermore, a Landau-type damping, due to the incoherence of the waves, whose role is to provide a stabilizing effect against the modulational instability, is both analytically and numerically discussed. PMID:12786485

  12. Landau damping and coherent structures in narrow-banded 1+1 deep water gravity waves

    NASA Astrophysics Data System (ADS)

    Onorato, Miguel; Osborne, Alfred; Fedele, Renato; Serio, Marina

    2003-04-01

    We study the modulational instability in surface gravity waves with random phase spectra. Starting from the nonlinear Schrödinger equation and using the Wigner-Moyal transform, we study the stability of the narrow-banded approximation of a typical wind-wave spectrum, i.e., the JONSWAP spectrum. By performing numerical simulations of the nonlinear Schrödinger equation we show that in the unstable regime, the nonlinear stage of the modulational instability is responsible for the formation of coherent structures. Furthermore, a Landau-type damping, due to the incoherence of the waves, whose role is to provide a stabilizing effect against the modulational instability, is both analytically and numerically discussed.

  13. Construction of narrow-band regenerative amplifier for momentum imaging spectroscopy of lithium dimer

    SciTech Connect

    Matsuoka, Leo; Hashimoto, Masashi; Yokoyama, Keiichi

    2012-07-11

    We constructed a Ti:Sapphire narrow-band regenerative amplifier as the probe laser of the experiment of momentum imaging spectroscopy of lithium dimer. The spectral profile of the regenerative cavity was designed by three birefringent filters and a plate of etalon. With 1.1-mJ pumping by the second harmonics of Nd:YLF laser, mode-locked seed pulses were amplified to {approx}25 {mu}J at 1-kHz repetition, with the bandwidth of {approx}0.7 cm{sup -1}.

  14. Measurement of the surface wavelength distribution of narrow-band radiation by a colorimetric method

    SciTech Connect

    Kraiskii, A V; Mironova, T V; Sultanov, T T

    2010-09-10

    A method is suggested for determining the wavelength of narrow-band light from a digital photograph of a radiating surface. The digital camera used should be appropriately calibrated. The accuracy of the wavelength measurement is better than 1 nm. The method was tested on the yellow doublet of mercury spectrum and on the adjacent continuum of the incandescent lamp radiation spectrum. By means of the method suggested the homogeneity of holographic sensor swelling was studied in stationary and transient cases. (laser applications and other topics in quantum electronics)

  15. A search for narrow band signals with SERENDIP II: a progress report.

    PubMed

    Werthimer, D; Brady, R; Berezin, A; Bowyer, S

    1988-01-01

    Commensal programs for the Search for Extraterrestrial Intelligence (SETI), carried out concurrently with conventional radio astronomical observing programs, can be an attractive and cost-effective means of exploring the large multidimensional search space intrinsic to this effort. Our automated commensal system, SERENDIP II, is a high resolution 131,072 channel spectrometer. It searches for 0.49 Hz signals in sequential 64,700 Hz bands of the IF signal from a radio telescope being used for an astronomical observation. Upon detection of a narrow band signal with power above a preset threshold, the frequency, power, time, and telescope direction are recorded for later study. The system has been tested at the Hat Creek Radio Astronomy Observatory 85 ft telescope and the NASA-JPL Deep Space Station (DSS 14) 64 m telescope. It is currently collecting data at the National Radio Astronomy Observatory 300 ft telescope. PMID:11538322

  16. A search for narrow band signals with SERENDIP II: a progress report

    NASA Technical Reports Server (NTRS)

    Werthimer, D.; Brady, R.; Berezin, A.; Bowyer, S.

    1988-01-01

    Commensal programs for the Search for Extraterrestrial Intelligence (SETI), carried out concurrently with conventional radio astronomical observing programs, can be an attractive and cost-effective means of exploring the large multidimensional search space intrinsic to this effort. Our automated commensal system, SERENDIP II, is a high resolution 131,072 channel spectrometer. It searches for 0.49 Hz signals in sequential 64,700 Hz bands of the IF signal from a radio telescope being used for an astronomical observation. Upon detection of a narrow band signal with power above a preset threshold, the frequency, power, time, and telescope direction are recorded for later study. The system has been tested at the Hat Creek Radio Astronomy Observatory 85 ft telescope and the NASA-JPL Deep Space Station (DSS 14) 64 m telescope. It is currently collecting data at the National Radio Astronomy Observatory 300 ft telescope.

  17. Novel schemes for the optimization of the SPARC narrow band THz source

    NASA Astrophysics Data System (ADS)

    Marchetti, B.; Bacci, A.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Mostacci, A.; Pompili, R.; Ronsivalle, C.; Spataro, B.; Zagorodnov, I.

    2015-07-01

    A pulsed, tunable, narrow band radiation source with frequency in the THz region can be obtained collecting the coherent transition radiation produced by a train of ultra-short electron bunches having picosecond scale inter-distance. In this paper, we review the techniques feasible at the SPARC_LAB test facility to produce and manipulate the requested train of electron bunches and we examine the dynamics of their acceleration and compression. In addition, we show how the performances of the train compression and the radiation intensity and bandwidth can be significantly improved through the insertion of a fourth order harmonic cavity, working in the X-band and acting as a longitudinal phase space linearizer.

  18. Narrow band wavelength selective filter using grating assisted single ring resonator

    SciTech Connect

    Prabhathan, P. Murukeshan, V. M.

    2014-09-15

    This paper illustrates a filter configuration which uses a single ring resonator of larger radius connected to a grating resonator at its drop port to achieve single wavelength selectivity and switching property with spectral features suitable for on-chip wavelength selection applications. The proposed configuration is expected to find applications in silicon photonics devices such as, on-chip external cavity lasers and multi analytic label-free biosensors. The grating resonator has been designed for a high Q-factor, high transmittivity, and minimum loss so that the wavelength selectivity of the device is improved. The proof-of-concept device has been demonstrated on a Silicon-on-Insulator (SOI) platform through electron beam lithography and Reactive Ion Etching (RIE) process. The transmission spectrum shows narrow band single wavelength selection and switching property with a high Free Spectral Range (FSR) ?60 nm and side band rejection ratio >15 dB.

  19. EVOLUTION OF [O III] {lambda}5007 EMISSION-LINE PROFILES IN NARROW EMISSION-LINE GALAXIES

    SciTech Connect

    Wang, J.; Mao, Y. F.; Wei, J. Y.

    2011-11-01

    The active galactic nucleus (AGN)-host co-evolution issue is investigated here by focusing on the evolution of the [O III] {lambda}5007 emission-line profile. A large sample of narrow emission-line galaxies is selected from the Max-Planck Institute for Astrophysics/Johns Hopkins University Sloan Digital Sky Survey DR7 catalog to simultaneously measure both the [O III] line profile and circumnuclear stellar population in an individual spectrum. By requiring that (1) the [O III] line signal-to-noise ratio is larger than 30 and (2) the [O III] line width is larger than the instrumental resolution by a factor of two, our sample is narrowed down to 2333 Seyfert galaxies/LINERs (AGNs), 793 transition galaxies, and 190 star-forming galaxies. In addition to the commonly used profile parameters (i.e., line centroid, relative velocity shift, and velocity dispersion), two dimensionless shape parameters, skewness and kurtosis, are used to quantify the line shape deviation from a pure Gaussian function. We show that the transition galaxies are systematically associated with narrower line widths and weaker [O III] broad wings than the AGNs, which implies that the kinematics of emission-line gas are different in the two kinds of objects. By combining the measured host properties and line shape parameters, we find that the AGNs with stronger blue asymmetries tend to be associated with younger stellar populations. However, a similar trend is not identified in the transition galaxies. The failure likely results from a selection effect in which the transition galaxies are systematically associated with younger stellar populations than the AGNs. The evolutionary significance revealed here suggests that both narrow-line region kinematics and outflow feedback in AGNs co-evolve with their host galaxies.

  20. Narrow band gap and enhanced thermoelectricity in FeSb2.

    PubMed

    Sun, Peijie; Oeschler, Niels; Johnsen, Simon; Iversen, Bo B; Steglich, Frank

    2010-01-28

    FeSb(2) was recently identified as a narrow-gap semiconductor with indications of strong electron-electron correlations. In this manuscript, we report on systematic thermoelectric investigation of a number of FeSb(2) single crystals with varying carrier concentrations, together with two isoelectronically substituted FeSb(2-x)As(x) samples (x = 0.01 and 0.03) and two reference compounds FeAs(2) and RuSb(2). Typical behaviour associated with narrow bands and narrow gaps is only confirmed for the FeSb(2) and the FeSb(2-x)As(x) samples. The maximum absolute thermopower of FeSb(2) spans from 10 to 45 mV/K at around 10 K, greatly exceeding that of both FeAs(2) and RuSb(2). The relation between the carrier concentration and the maximum thermopower value is in approximate agreement with theoretical predictions of the electron-diffusion contribution which, however, requires an enhancement factor larger than 30. The isoelectronic substitution leads to a reduction of the thermal conductivity, but the charge-carrier mobility is also largely reduced due to doping-induced crystallographic defects or impurities. In combination with the high charge-carrier mobility and the enhanced thermoelectricity, FeSb(2) represents a promising candidate for thermoelectric cooling applications at cryogenic temperatures. PMID:20066185

  1. Development of narrow-band fluorescence index for the detection of aflatoxin contaminated corn

    NASA Astrophysics Data System (ADS)

    Yao, Haibo; Hruska, Zuzana; Kincaid, Russell; Ononye, Ambrose; Brown, Robert L.; Bhatnagar, Deepak; Cleveland, Thomas E.

    2011-06-01

    Aflatoxin is produced by the fungus Aspergillus flavus when the fungus invades developing corn kernels. Because of its potent toxicity, the levels of aflatoxin are regulated by the Food and Drug Administration (FDA) in the US, allowing 20 ppb (parts per billion) limits in food, and feed intended for interstate commerce. Currently, aflatoxin detection and quantification methods are based on analytical tests. These tests require the destruction of samples, can be costly and time consuming, and often rely on less than desirable sampling techniques. Thus, the ability to detect aflatoxin in a rapid, non-invasive way is crucial to the corn industry in particular. This paper described how narrow-band fluorescence indices were developed for aflatoxin contamination detection based on single corn kernel samples. The indices were based on two bands extracted from full wavelength fluorescence hyperspectral imagery. The two band results were later applied to two large sample experiments with 25 g and 1 kg of corn per sample. The detection accuracies were 85% and 95% when 100 ppb threshold was used. Since the data acquisition period is significantly lower for several image bands than for full wavelength hyperspectral data, this study would be helpful in the development of real-time detection instrumentation for the corn industry.

  2. Nature of the narrow optical band in H*-aggregates: Dozy-chaos–exciton coupling

    SciTech Connect

    Egorov, Vladimir V.

    2014-07-15

    Dozy chaos emerges as a combined effect of the collective chaotic motion of electrons and nuclei, and their chaotic electromagnetic interactions in the transient state of molecules experiencing quantum transitions. Following earlier discussions of the well-known Brönsted relations for proton-transfer reactions; the temperature-dependent electron transfer in Langmuir–Blodgett films; the shape of the optical bands of polymethine dye monomers, their dimers, and J-aggregates, this paper reports one more application of the dozy-chaos theory of molecular quantum transitions. The qualitative and quantitative explanations for shape of a narrow and blue-shifted optical absorption band in H{sup *}-aggregates is given on the basis of the dozy-chaos theory by taking into account the dozy-chaos–exciton coupling effect. It is emphasized that in the H{sup *}-aggregate chromophore (dimer of cyclic bis-thiacarbocyanines) there is a competition between two Frenkel exciton transitions through the chaotic reorganization motion of nuclear environment. As a result, the highly organized quantum transition to the upper exciton state becomes an exciton-induced source of dozy chaos for the low organized transition to the lower exciton state. This manifests itself in appearing the narrow peak and broad wing in the optical spectrum pattern of H{sup *}-aggregates. A similar enhancement in the H{sup *}-effect caused by the strengthening of the exciton coupling in H{sup *}-dimers, which could be achieved by synthesizing tertiary and quarternary thiacarbocyanine monomers, is predicted.

  3. Nature of the narrow optical band in H*-aggregates: Dozy-chaos-exciton coupling

    NASA Astrophysics Data System (ADS)

    Egorov, Vladimir V.

    2014-07-01

    Dozy chaos emerges as a combined effect of the collective chaotic motion of electrons and nuclei, and their chaotic electromagnetic interactions in the transient state of molecules experiencing quantum transitions. Following earlier discussions of the well-known Brönsted relations for proton-transfer reactions; the temperature-dependent electron transfer in Langmuir-Blodgett films; the shape of the optical bands of polymethine dye monomers, their dimers, and J-aggregates, this paper reports one more application of the dozy-chaos theory of molecular quantum transitions. The qualitative and quantitative explanations for shape of a narrow and blue-shifted optical absorption band in H*-aggregates is given on the basis of the dozy-chaos theory by taking into account the dozy-chaos-exciton coupling effect. It is emphasized that in the H*-aggregate chromophore (dimer of cyclic bis-thiacarbocyanines) there is a competition between two Frenkel exciton transitions through the chaotic reorganization motion of nuclear environment. As a result, the highly organized quantum transition to the upper exciton state becomes an exciton-induced source of dozy chaos for the low organized transition to the lower exciton state. This manifests itself in appearing the narrow peak and broad wing in the optical spectrum pattern of H*-aggregates. A similar enhancement in the H*-effect caused by the strengthening of the exciton coupling in H*-dimers, which could be achieved by synthesizing tertiary and quarternary thiacarbocyanine monomers, is predicted.

  4. In vivo early diagnosis of gastric dysplasia using narrow-band image-guided Raman endoscopy

    NASA Astrophysics Data System (ADS)

    Huang, Zhiwei; Bergholt, Mads Sylvest; Zheng, Wei; Lin, Kan; Ho, Khek Yu; Teh, Ming; Yeoh, Khay Guan

    2010-05-01

    We first report on the implementation of a novel narrow-band image-guided Raman endoscopy technique for in vivo diagnosis of gastric dysplasia. High-quality in vivo Raman spectra can be acquired from normal and dysplastic gastric mucosal tissue within 0.5 sec under narrow-band image (NBI) guidance at gastroscopy. Significant differences are observed in in vivo Raman spectra between normal (n=54) and dysplastic (n=18) gastric tissue from 30 gastric patients, particularly in the spectral ranges of 825 to 950, 1000 to 1100, 1250 to 1500, and 1600 to 1800 cm-1, which primarily contain signals related to proteins, nucleic acids, and lipids. The multivariate analysis [i.e., principal components analysis (PCA) and linear discriminant analysis (LDA)], together with the leave-one tissue site-out, cross validation on in vivo gastric Raman spectra yields a diagnostic sensitivity of 94.4% (17/18) and specificity of 96.3% (52/54) for distinction of gastric dysplastic tissue. This study suggests that narrowband image-guided Raman endoscopy associated with PCA-LDA diagnostic algorithms has potential for the noninvasive, in vivo early diagnosis and detection of gastric precancer during clinical gastroscopic examination.

  5. Narrow-band N-resonance formed in thin rubidium atomic layers

    SciTech Connect

    Sargsyan, A.; Mirzoyan, R.; Sarkisyan, D.

    2012-11-15

    The narrow-band N-resonance formed in a {Lambda} system of D{sub 1}-line rubidium atoms is studied in the presence of a buffer gas (neon) and the radiations of two continuous narrow-band diode lasers. Special-purpose cells are used to investigate the dependence of the process on vapor column thickness L in millimeter, micrometer, and nanometer ranges. A comparison of the dependences of the N-resonance and the electromagnetically induced transparency (EIT) resonance on L demonstrates that the minimum (record) thickness at which the N-resonance can be detected is L = 50 {mu}m and that a high-contrast EIT resonance can easily be formed even at L Almost-Equal-To 800 nm. The N-resonance in a magnetic field for {sup 85}Rb atoms is shown to split into five or six components depending on the magnetic field and laser radiation directions. The results obtained indicate that levels F{sub g} = 2, 3 are initial and final in the N-resonance formation. The dependence of the N-resonance on the angle between the laser beams is analyzed, and practical applications are noted.

  6. Narrow-band imaging and velocity maps of young stellar objects - Initial results

    NASA Technical Reports Server (NTRS)

    Morgan, J. S.; Wolff, S. C.; Strom, S. E.; Strom, K. M.

    1984-01-01

    The first trials of a new technique, designed to map low-excitation ionized gas surrounding young stellar objects, are reported. The region surrounding the T Tau stars HL Tau and XZ Tau, that near HH 101, and that near IRS 5 in L1551 have been imaged through a narrow-band (4.7 A FWHM) forbidden S II filter; three-phase CCD chip was used as the detector. By tilting the narrow-band filter, it is possible to vary the wavelength of peak transmission and thus to detect high-velocity radial flows as well as map the morphology of the excited gas near these young stars. Evidence of an apparently helical outflow is found for HH 101. Redshifted gas appears to extend southward from HL Tau toward HH 30; a blueshifted jet extends northeastward of HL Tau. A series of forbidden S II knots is seen to extend along a jet directed southwestward from the infrared source IRS 5; the knot chain appears to delineate a blueshifted outflow that decelerates as it recedes from IRS 5.

  7. Correlation of Narrow Band Imaging Endoscopy and Histopathology in the Diagnosis of Nonerosive Reflux Disease

    PubMed Central

    Arul, P; Vinoth, B; Alexander, Thomas; Phansalkar, Manjiri; Padhi, Somanath

    2015-01-01

    Background /Aim: Narrow band imaging (NBI) is a novel, innovative high-resolution endoscopic technique, which utilizes spectral narrow band filter for the visualization of mucosal patterns and microvasculature. Nonerosive reflux disease (NERD) is a type of gastroesophageal reflux disease (GERD) and it is characterized by reflux symptoms without mucosal breaks on white light endoscopy (WLE). Biopsies from distal esophagus of GERD patients show group of histologic features such as basal cell hyperplasia, elongation of lamina propria papillae, and inflammatory cells. The present study was undertaken to evaluate diagnostic utility of NBI endoscopy and biopsy study in NERD patients and also to correlate NBI endoscopy findings with histologic features of GERD. Patients and Methods: A total of 71 cases of NERD having symptom score more than 10 and those not having erosion on WLE were recruited prospectively and underwent NBI endoscopic examination. Two mucosal biopsies were taken at 3 cm above the squamocolumnar junction. Results: Histologic features of GERD were seen in 50 (70.4%) out of 71 cases. No significant correlation between NBI endoscopic findings with histologic features of GERD was found. Conclusion: The present study showed that histopathologic evaluation of distal esophageal mucosa has promising diagnostic value over NBI endoscopy in NERD patients. Use of newly introduced NBI technique requires tremendous familiarity for the detection of the cases of NERD, which show histologic features of GERD. PMID:26458862

  8. Compact high-quality CdSe/CdS core/shell nanocrystals with narrow emission linewidths and suppressed blinking

    E-print Network

    Chen, Ou

    High particle uniformity, high photoluminescence quantum yields, narrow and symmetric emission spectral lineshapes and minimal single-dot emission intermittency (known as blinking) have been recognized as universal ...

  9. Discovery of 9 Ly alpha emitters at redshift z~3.1 using narrow-band imaging and VLT spectroscopy

    E-print Network

    R. P. Kudritzki; R. H. Mendez; J. J. Feldmeier; R. Ciardullo; G. H. Jacoby; K. C. Freeman; M. Arnaboldi; M. Capaccioli; O. Gerhard; H. C. Ford

    2000-01-10

    Narrow-band imaging surveys aimed at detecting the faint emission from the 5007 [O III] line of intracluster planetary nebulae in Virgo also probe high redshift z=3.1 Ly alpha emitters. Here we report on the spectroscopic identification of 9 Ly alpha emitters at z=3.13, obtained with the FORS spectrograph at Unit 1 of the ESO Very Large Telescope (VLT UT1). The spectra of these high redshift objects show a narrow, isolated Ly alpha emission with very faint (frequently undetected) continuum, indicating a large equivalent width. No other features are visible in our spectra. Our Ly alpha emitters are quite similar to those found by Hu (1998), Cowie & Hu (1998) and Hu et al. (1998). Using simple population synthesis models, on the assumption that these sources are regions of star formation, we conclude that the nebulae are nearly optically thick and must have a very low dust content, in order to explain the high observed Ly alpha equivalent widths. For the cosmological and star formation parameters we adopted, the total stellar mass produced would seem to correspond to the formation of rather small galaxies, some of which are perhaps destined to merge. The implied star formation density in our sampled comoving volume is probably somewhat smaller than, but of the same order of magnitude as the star formation density at z=3 derived by other authors from Lyman-break galaxy surveys. This result agrees with the expectation that the Ly alpha emitters are a low-metallicity (or low-dust) tail in a distribution of star forming regions at high redshifts. Finally, the Ly alpha emitters may contribute as many H-ionizing photons as QSOs at z=3.

  10. On the first-excursion probability in stationary narrow-band random vibration. II.

    NASA Technical Reports Server (NTRS)

    Yang, J.-N.; Shinozuka, M.

    1972-01-01

    The first-excursion probability of a stationary narrow-band Gaussian process with mean zero has been studied. Within the framework of point process approach, series approximations derived from the theory of random points and approximations based on the maximum entropy principle have been developed. With the aid of numerical examples, merits of the approximations proposed previously as well as of those developed in this paper have been compared. The results indicate that the maximum entropy principle has not produced satisfactory approximations but the approximation based on nonapproaching random points is found to be the best among all the approximations proposed herein. A conclusion drawn from the present and the previous studies is that the point process approach produces a number of useful approximations for the first-excursion probability, particularly those based on the concepts of the Markov process, the clump-size, and the nonapproaching random points.

  11. The Safety and Efficacy of Narrow Band Ultraviolet B Treatment in Dermatology: A Review.

    PubMed

    Sokolova, Anna; Lee, Andrew; D Smith, Saxon

    2015-12-01

    Narrow-band ultraviolet B (NBUVB) phototherapy is an important treatment modality in dermatology. The most common dermatological indications for NBUVB include psoriasis, atopic dermatitis and vitiligo; however, it has been found to be an effective and well-tolerated treatment option in various other dermatoses. The efficacy of NBUVB phototherapy compares favorably with other available photo(chemo)therapy options and its efficacy is further augmented by a number of topical and systemic adjuncts. The long-term safety of NBUVB phototherapy remains to be fully elucidated; however, available data now suggest that it is safe and well-tolerated. The objective of this review was to summarize the current understanding of the safety and efficacy of NBUVB phototherapy in dermatology. PMID:26369540

  12. Simulator spectral characterization using balloon calibrated solar cells with narrow band pass filters

    NASA Technical Reports Server (NTRS)

    Goodelle, G. S.; Brooks, G. R.; Seaman, C. H.

    1981-01-01

    The development and implementation of an instrument for spectral measurement of solar simulators for testing solar cell characteristics is reported. The device was constructed for detecting changes in solar simulator behavior and for comparing simulator spectral irradiance to solar AM0 output. It consists of a standard solar cell equipped with a band pass filter narrow enough so that, when flown on a balloon to sufficient altitude along with sufficient numbers of cells, each equipped with filters of different bandpass ratings, the entire spectral response of the standard cell can be determined. Measured short circuit currents from the balloon flights thus produce cell devices which, when exposed to solar simulator light, have a current which does or does not respond as observed under actual AM0 conditions. Improvements of the filtered cells in terms of finer bandpass filter tuning and measurement of temperature coefficients are indicated.

  13. Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 1. Overview).

    SciTech Connect

    Fujita,E.; Khalifah, P.; Lymar, S.; Muckerman, J.T.; Rodgriguez, J.

    2008-03-18

    The objectives of this report are: (1) Investigate the catalysis of water oxidation by cobalt and manganese hydrous oxides immobilized on titania or silica nanoparticles, and dinuclear metal complexes with quinonoid ligands in order to develop a better understanding of the critical water oxidation chemistry, and rationally search for improved catalysts. (2) Optimize the light-harvesting and charge-separation abilities of stable semiconductors including both a focused effort to improve the best existing materials by investigating their structural and electronic properties using a full suite of characterization tools, and a parallel effort to discover and characterize new materials. (3) Combine these elements to examine the function of oxidation catalysts on Band-Gap-Narrowed Semiconductor (BGNSC) surfaces and elucidate the core scientific challenges to the efficient coupling of the materials functions.

  14. Narrow-Band Imagery of New Planetary Nebula Candidates at High Galactic Latitudes.

    NASA Astrophysics Data System (ADS)

    Kronberger, Matthias; Jacoby, George H.; Harmer, Dianne

    2013-08-01

    We propose a narrowband imaging campaign to verify the classification of 45 Galactic planetary nebula candidates discovered thus far on digitized sky surveys, following up an imaging and spectroscopy program started at KPNO, OHP, SAAO and UNAM. The majority of the candidates are located outside of the Milky Way regions covered by recent narrow-band surveys (IPHAS and SHS) that are limited to low Galactic latitudes (|b| > 5° and |b| > 10° for candidates north and south of +2° declination, respectively). Due to their large projected angle from the Galactic plane, many of the new candidates are likely to belong to the local volume (< 1kpc from the Sun). Thus, we will better estimate the total number of planetary nebulae in our Galaxy (extrapolated from the local volume), a metric that offers a critical test of the hypothesis that most planetary nebulae derive from binaries.

  15. Narrow-Band Imagery of New Planetary Nebula Candidates at High Galactic Latitudes.

    NASA Astrophysics Data System (ADS)

    Kronberger, Matthias; Jacoby, George H.; Harmer, Dianne

    2013-02-01

    We propose a narrowband imaging campaign to verify the classification of 26 Galactic planetary nebula candidates discovered thus far on digitized sky surveys, following up an imaging and spectroscopy program started at KPNO, OHP, SAAO and UNAM. The majority of the candidates are located outside of the Milky Way regions covered by recent narrow-band surveys (IPHAS and SHS) that are limited to low Galactic latitudes (|b| > 5^circ and |b| > 10^circ for candidates north and south of +2^circ declination, respectively). Due to their large projected angle from the Galactic plane, many of the new candidates are likely to belong to the local volume (< 1kpc from the Sun). Thus, we will better estimate the total number of planetary nebulae in our Galaxy (extrapolated from the local volume), a metric that offers a critical test of the hypothesis that most planetary nebulae derive from binaries.

  16. Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 2. Overview).

    SciTech Connect

    Fujita,E.; Khalifah, P.; Lymar, S.; Muckerman, J.T.; Rodriguez, J.

    2008-03-18

    The objectives of this report are: (1) Investigate the catalysis of water oxidation by cobalt and manganese hydrous oxides immobilized on titania or silica nanoparticles, and dinuclear metal complexes with quinonoid ligands in order to develop a better understanding of the critical water oxidation chemistry, and rationally search for improved catalysts. (2) Optimize the light-harvesting and charge-separation abilities of stable semiconductors including both a focused effort to improve the best existing materials by investigating their structural and electronic properties using a full suite of characterization tools, and a parallel effort to discover and characterize new materials. (3) Combine these elements to examine the function of oxidation catalysts on Band-Gap-Narrowed Semiconductor (BGNSC) surfaces and elucidate the core scientific challenges to the efficient coupling of the materials functions.

  17. The method of narrow-band audio classification based on universal noise background model

    NASA Astrophysics Data System (ADS)

    Rui, Rui; Bao, Chang-chun

    2013-03-01

    Audio classification is the basis of content-based audio analysis and retrieval. The conventional classification methods mainly depend on feature extraction of audio clip, which certainly increase the time requirement for classification. An approach for classifying the narrow-band audio stream based on feature extraction of audio frame-level is presented in this paper. The audio signals are divided into speech, instrumental music, song with accompaniment and noise using the Gaussian mixture model (GMM). In order to satisfy the demand of actual environment changing, a universal noise background model (UNBM) for white noise, street noise, factory noise and car interior noise is built. In addition, three feature schemes are considered to optimize feature selection. The experimental results show that the proposed algorithm achieves a high accuracy for audio classification, especially under each noise background we used and keep the classification time less than one second.

  18. A proposed interim improvement to the Tevatron beam position monitors with narrow band crystal filters

    SciTech Connect

    Cheng-Yang Tan

    2003-08-25

    Since the start of Run II, we have found that we are unable to reliably and accurately measure the beam position with the present BPM system during high energy physics (HEP). This problem can be traced back to the analogue frontend called the AM/PM module which has trouble handling coalesced beam, but works well with uncoalesced beam. In this paper, we propose a simple fix to the AM/PM module so that we can measure the beam position during HEP. The idea is to use narrow band crystal filters which ring when pinged by coalesced beam so that the AM/PM module is tricked into thinking that it is measuring uncoalesced beam.

  19. Band gap narrowing in zinc oxide-based semiconductor thin films

    SciTech Connect

    Kumar, Jitendra E-mail: akrsri@gmail.com; Kumar Srivastava, Amit E-mail: akrsri@gmail.com

    2014-04-07

    A simple expression is proposed for the band gap narrowing (or shrinkage) in semiconductors using optical absorption measurements of spin coated 1 at.?% Ga-doped ZnO (with additional 0–1.5 at.?% zinc species) thin films as ?E{sub BGN}?=?Bn{sup 1/3} [1 ? (n{sub c}/n){sup 1/3}], where B is the fitting parameter, n is carrier concentration, and n{sub c} is the critical density required for shrinkage onset. Its uniqueness lies in not only describing variation of ?E{sub BGN} correctly but also allowing deduction of n{sub c} automatically for several M-doped ZnO (M: Ga, Al, In, B, Mo) systems. The physical significance of the term [1 ? (n{sub c}/n){sup 1/3}] is discussed in terms of carrier separation.

  20. H-tailored surface conductivity in narrow band gap In(AsN)

    SciTech Connect

    Velichko, A. V. E-mail: anton.velychko@nottingham.ac.uk; Patanè, A. E-mail: anton.velychko@nottingham.ac.uk; Makarovsky, O.; Capizzi, M.; Polimeni, A.; Sandall, I. C.; Tan, C. H.; Giubertoni, D.; Krier, A.; Zhuang, Q.

    2015-01-12

    We show that the n-type conductivity of the narrow band gap In(AsN) alloy can be increased within a thin (?100?nm) channel below the surface by the controlled incorporation of H-atoms. This channel has a large electron sheet density of ?10{sup 18?}m{sup ?2} and a high electron mobility (??>?0.1 m{sup 2}V{sup ?1}s{sup ?1} at low and room temperature). For a fixed dose of impinging H-atoms, its width decreases with the increase in concentration of N-atoms that act as H-traps thus forming N-H donor complexes near the surface.

  1. Program for narrow-band analysis of aircraft flyover noise using ensemble averaging techniques

    NASA Technical Reports Server (NTRS)

    Gridley, D.

    1982-01-01

    A package of computer programs was developed for analyzing acoustic data from an aircraft flyover. The package assumes the aircraft is flying at constant altitude and constant velocity in a fixed attitude over a linear array of ground microphones. Aircraft position is provided by radar and an option exists for including the effects of the aircraft's rigid-body attitude relative to the flight path. Time synchronization between radar and acoustic recording stations permits ensemble averaging techniques to be applied to the acoustic data thereby increasing the statistical accuracy of the acoustic results. Measured layered meteorological data obtained during the flyovers are used to compute propagation effects through the atmosphere. Final results are narrow-band spectra and directivities corrected for the flight environment to an equivalent static condition at a specified radius.

  2. Ultra-narrow band perfect absorbers based on plasmonic analog of electromagnetically induced absorption.

    PubMed

    He, Jinna; Ding, Pei; Wang, Junqiao; Fan, Chunzhen; Liang, Erjun

    2015-03-01

    A novel plasmonic metamaterial consisting of the solid (bar) and the inverse (slot) compound metallic nanostructure for electromagnetically induced absorption (EIA) is proposed in this paper, which is demonstrated to achieve an ultra-narrow absorption peak with the linewidth less than 8 nm and the absorptivity exceeding 97% at optical frequencies. This is attributed to the plasmonic EIA resonance arising from the efficient coupling between the magnetic response of the slot (dark mode) and the electric resonance of the bar (bright mode). To the best of our knowledge, this is the first time that the plasmonic EIA is used to realize the narrow-band perfect absorbers. The underlying physics are revealed by applying the two-coupled-oscillator model. The near-perfect-absorption resonance also causes an enhancement of about 50 times in H-field and about 130 times in E-field within the slots. Such absorber possesses potential for applications in filter, thermal emitter, surface enhanced Raman scattering, sensing and nonlinear optics. PMID:25836832

  3. Five years of comet narrow band photometry and imaging with TRAPPIST

    NASA Astrophysics Data System (ADS)

    Opitom, Cyrielle; Jehin, Emmanuel; Manfroid, Jean; Hutsemékers, Damien; Gillon, Michaël; Magain, Pierre

    2015-11-01

    TRAPPIST is a 60-cm robotic telescope in La Silla Observatory [1] mainly dedicated to the study of exoplanets and comets. The telescope is equipped with a set of narrow band cometary filters designed by the NASA for the Hale-Bopp observing campaign [2]. Since its installation in 2010, we gathered a high quality and homogeneous data set of more than 30 bright comets observed with narrow band filters. Some comets were only observed for a few days but others have been observed weekly during several months on both sides of perihelion. From the images, we derived OH, NH, CN, C2, and C3 production rates using a Haser [3] model in addition to the Af? parameter as a proxy for the dust production. We computed production rates ratios and the dust color for each comet to study their composition and followed the evolution of these ratios and colors with the heliocentric distance.The TRAPPIST data set, rich of more than 10000 images obtained and reduced in an homogeneous way, allows us to address several fundamental questions such as the pristine or evolutionary origin of composition differences among comets. The evolution of comet activity with the heliocentric distance, the differences between species, and from comet to comet, will be discussed. Finally, the first results about the one year campaign on comet C/2013 US10 (Catalina) and our recent work on the re-determination of Haser scalelengths will be presented.[1] Jehin et al., The Messenger, 145, 2-6, 2011[2] Farnham et al., Icarus, 147, 180-204, 2000[3] Haser, Bulletin de l’Académie Royal des Sciences de Belgique,63, 739, 1957

  4. Narrow-band wavelength tunable filter based on asymmetric double layer metallic grating.

    PubMed

    Liang, Yuzhang; Peng, Wei; Lu, Mengdi; Chu, Shuwen

    2015-06-01

    In this paper, the optical properties of asymmetric double layer metallic gratings are presented theoretically. The asymmetric structure is achieved by two main factors: one corresponding to moving alternatively metal nanowires of the top layer metallic grating, the other corresponding to possessing different thickness of the top and down layer metallic gratings. Our proposed structure shows one remarkable narrow-band transmission dip at normal incidence, which is distinct different from that of symmetric structure. The results are further confirmed by using different numerical computation methods, and explained by the analytical model of Fano-like resonance. We find that, only when the thickness of the down layer metallic grating has certain fixed value, transmission dip can be transformed from two to only one dip even if the existence of symmetry breaking. However, the wavelength position of the dip can be easily controlled by adjusting the thickness of the top layer metallic grating without the need to modify the structure period, and the width of metal nanowire. Moreover, the influence of other structure parameters on the dip is also investigated. Surprisingly, in order to keep the appearance of one dip in the transmission spectrum of designed structure, there is a good linear approximation between the refractive index of waveguide layer and the thickness of down layer metallic grating, and the relation of waveguide layer thickness and the thickness of down layer metallic grating satisfy secondary polynomial fitting. This work can be used to develop subwavelength metallic-grating-based and narrow-band tunable wavelength filters. PMID:26072805

  5. Narrow- and broad-band satellite measurements of shortwave radiation - Conversion simulations with a general circulation model

    NASA Technical Reports Server (NTRS)

    Cess, Robert D.; Potter, Gerald L.

    1986-01-01

    The Oregon State University/Lawrence Livermore National Laboratory general circulation model has been employed as a vehicle for suggesting and exploring various means of converting narrow-band measurements of reflected solar radiation from the earth-atmosphere system to broad-band quantities. For purely illustrative purposes within the model's solar radiation routine, a narrow-band filter function consisting of a square-wave window extending from 0.5 to 0.9 microns is adopted. A limitation of the model, for this sort of endeavor, is that it does not include the wavelength dependence of surface albedos. Nevertheless, the model simulations tend to mimic the calibration of a narrow-band instrument, utilizing reflected solar radiation from the earth-atmosphere system as simultaneously measured by a collocated broad-band instrument; for the model, however, this is done in terms of fluxes, in contrast to instrument-measured radiances. The model results suggest that it might be preferable to perform narrow- to broad-band conversions in terms of planetary albedo (or an equivalent quantity), rather than in terms of reflected fluxes or radiances. Further improvement is achieved if, for instruments that can differentiate between clear and overcast conditions, separate clear and overcast calibrations are performed.

  6. New Design of Integrated 2D Photonic Crystal Narrow Band Filters Using the FDTD-2D Method

    NASA Astrophysics Data System (ADS)

    Badaoui, Hadjira Abri; Abri, Mehadji

    2014-11-01

    In this paper, integrated 2D photonic crystal narrow band filter design is achieved based on transmission spectra shift. The presented effective technique for the design of narrow band resonant filters obtained by one-missing-row and by choosing proper radii of air holes of the waveguide is proposed. The 2D photonic crystals are designed by utilizing cascaded waveguides with different radii of air holes. The results are presented for normal incident wave with TE polarizations with a narrow spectral bandwidth centered at ? = 1.55 ?m. We also discuss the filtering process and its necessary modifications to achieve efficient filtering. A final synthesized filter topology is presented and a band from 1.53 ?m to 1.57 ?m around 1.55 ?m is transmitted with a maximum transmission of about 77% with better performances is achieved.

  7. An enhanced transform domain communication system (ETDCS) with narrow-band interference (NBI) avoidance capability

    NASA Astrophysics Data System (ADS)

    Jo, Youngho; Wu, Dapeng

    2009-05-01

    Reliable communication over hostile environment is desired by both military and civilian parties. In this paper, we propose an enhanced transform domain communication system (ETDCS) with narrow-band interference (NBI) avoidance capability. The basic idea for this system is to synthesize adaptive waveform in the frequency domain by a non-parametric spectral estimator, called Capon's method, at both the transmitter and the receiver to avoid spectrally crowded regions. This approach offers better bit error performance than existing similar systems such as the transform domain communication system (TDCS) that utilizes a parametric autoregressive (AR) spectral estimator, the wavelet domain communication system (WDCS) which uses wavelet domain periodogram, or the enhanced wavelet domain communication system (EWDCS) which employs the evolutionary wavelet spectrum (EWS). Specifically, our proposed ETDCS significantly improves the bit error performance under non-stationary interference such as swepttone interference while achieving consistent bit error performance under stationary interference such as partial band, singletone, and multitone interference. Hence, our proposed ETDCS provides a viable alternative for highly reliable communication in interference rich communication environments.

  8. A blue optical filter for narrow-band imaging in endoscopic capsules

    NASA Astrophysics Data System (ADS)

    Silva, M. F.; Ghaderi, M.; Goncalves, L. M.; de Graaf, G.; Wolffenbuttel, R. F.; Correia, J. H.

    2014-05-01

    This paper presents the design, simulation, fabrication, and characterization of a thin-film Fabry-Perot resonator composed of titanium dioxide (TiO2) and silicon dioxide (SiO2) thin-films. The optical filter is developed to be integrated with a light emitting diode (LED) for enabling narrow-band imaging (NBI) in endoscopy. The NBI is a high resolution imaging technique that uses spectrally centered blue light (415 nm) and green light (540 nm) to illuminate the target tissue. The light at 415 nm enhances the imaging of superficial veins due to their hemoglobin absorption, while the light at 540 nm penetrates deeper into the mucosa, thus enhances the sub-epithelial vessels imaging. Typically the endoscopes and endoscopic capsules use white light for acquiring images of the gastrointestinal (GI) tract. However, implementing the NBI technique in endoscopic capsules enhances their capabilities for the clinical applications. A commercially available blue LED with a maximum peak intensity at 404 nm and Full Width Half Maximum (FWHM) of 20 nm is integrated with a narrow band blue filter as the NBI light source. The thin film simulations show a maximum spectral transmittance of 36 %, that is centered at 415 nm with FWHM of 13 nm for combined the blue LED and a Fabry Perot resonator system. A custom made deposition scheme was developed for the fabrication of the blue optical filter by RF sputtering. RF powered reactive sputtering at 200 W with the gas flows of argon and oxygen that are controlled for a 5:1 ratio gives the optimum optical conditions for TiO2 thin films. For SiO2 thin films, a non-reactive RF sputtering at 150 W with argon gas flow at 15 sccm results in the best optical performance. The TiO2 and SiO2 thin films were fully characterized by an ellipsometer in the wavelength range between 250 nm to 1600 nm. Finally, the optical performance of the blue optical filter is measured and presented.

  9. Narrow band quantitative and multivariate electroencephalogram analysis of peri-adolescent period

    PubMed Central

    2012-01-01

    Background The peri-adolescent period is a crucial developmental moment of transition from childhood to emergent adulthood. The present report analyses the differences in Power Spectrum (PS) of the Electroencephalogram (EEG) between late childhood (24 children between 8 and 13 years old) and young adulthood (24 young adults between 18 and 23 years old). Results The narrow band analysis of the Electroencephalogram was computed in the frequency range of 0–20 Hz. The analysis of mean and variance suggested that six frequency ranges presented a different rate of maturation at these ages, namely: low delta, delta-theta, low alpha, high alpha, low beta and high beta. For most of these bands the maturation seems to occur later in anterior sites than posterior sites. Correlational analysis showed a lower pattern of correlation between different frequencies in children than in young adults, suggesting a certain asynchrony in the maturation of different rhythms. The topographical analysis revealed similar topographies of the different rhythms in children and young adults. Principal Component Analysis (PCA) demonstrated the same internal structure for the Electroencephalogram of both age groups. Principal Component Analysis allowed to separate four subcomponents in the alpha range. All these subcomponents peaked at a lower frequency in children than in young adults. Conclusions The present approaches complement and solve some of the incertitudes when the classical brain broad rhythm analysis is applied. Children have a higher absolute power than young adults for frequency ranges between 0-20 Hz, the correlation of Power Spectrum (PS) with age and the variance age comparison showed that there are six ranges of frequencies that can distinguish the level of EEG maturation in children and adults. The establishment of maturational order of different frequencies and its possible maturational interdependence would require a complete series including all the different ages. PMID:22920159

  10. Narrow-band search of continuous gravitational-wave signals from Crab and Vela pulsars in Virgo VSR4 data

    E-print Network

    Aasi, J.

    In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small ...

  11. 47 CFR 80.361 - Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions. 80.361 Section 80.361 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Frequencies Radiotelegraphy § 80.361 Frequencies...

  12. 47 CFR 80.219 - Special requirements for narrow-band direct-printing (NB-DP) equipment.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of these standards can be inspected...-printing (NB-DP) equipment. 80.219 Section 80.219 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... § 80.219 Special requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP and...

  13. 47 CFR 80.219 - Special requirements for narrow-band direct-printing (NB-DP) equipment.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-printing (NB-DP) equipment. 80.219 Section 80.219 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... § 80.219 Special requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP and data...-DP and data transmission equipment are additionally permitted to utilize any modulation, so long...

  14. 47 CFR 80.219 - Special requirements for narrow-band direct-printing (NB-DP) equipment.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-printing (NB-DP) equipment. 80.219 Section 80.219 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... § 80.219 Special requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP and data...-DP and data transmission equipment are additionally permitted to utilize any modulation, so long...

  15. 47 CFR 80.219 - Special requirements for narrow-band direct-printing (NB-DP) equipment.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of these standards can be inspected...-printing (NB-DP) equipment. 80.219 Section 80.219 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... § 80.219 Special requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP and...

  16. 47 CFR 80.219 - Special requirements for narrow-band direct-printing (NB-DP) equipment.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-printing (NB-DP) equipment. 80.219 Section 80.219 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... § 80.219 Special requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP and data...-DP and data transmission equipment are additionally permitted to utilize any modulation, so long...

  17. Synchrotron Studies of Narrow Band and Low-Dimensional Materials. Final Report for July 1, 1990---December 31, 2002

    SciTech Connect

    Allen, J. W.

    2003-05-13

    This report summarizes a 12-year program of various kinds of synchrotron spectroscopies directed at the electronic structures of narrow band and low-dimensional materials that display correlated electron behaviors such as metal-insulator transitions, mixed valence, superconductivity, Kondo moment quenching, heavy Fermions, and non-Fermi liquid properties.

  18. Light-Emitting Diode-Assisted Narrow Band Imaging Video Endoscopy System in Head and Neck Cancer

    PubMed Central

    Chang, Hsin-Jen; Wang, Wen-Hung; Chang, Yen-Liang; Jeng, Tzuan-Ren; Wu, Chun-Te; Angot, Ludovic; Lee, Chun-Hsing

    2015-01-01

    Background/Aims To validate the effectiveness of a newly developed light-emitting diode (LED)-narrow band imaging (NBI) system for detecting early malignant tumors in the oral cavity. Methods Six men (mean age, 51.5 years) with early oral mucosa lesions were screened using both the conventional white light and LED-NBI systems. Results Small elevated or ulcerative lesions were found under the white light view, and typical scattered brown spots were identified after shifting to the LED-NBI view for all six patients. Histopathological examination confirmed squamous cell carcinoma. The clinical stage was early malignant lesions (T1), and the patients underwent wide excision for primary cancer. This is the pilot study documenting the utility of a new LED-NBI system as an adjunctive technique to detect early oral cancer using the diagnostic criterion of the presence of typical scattered brown spots in six high-risk patients. Conclusions Although large-scale screening programs should be established to further verify the accuracy of this technology, its lower power consumption, lower heat emission, and higher luminous efficiency appear promising for future clinical applications. PMID:25844342

  19. Quantitative evaluation of mucosal vascular contrast in narrow band imaging using Monte Carlo modeling

    NASA Astrophysics Data System (ADS)

    Le, Du; Wang, Quanzeng; Ramella-Roman, Jessica; Pfefer, Joshua

    2012-06-01

    Narrow-band imaging (NBI) is a spectrally-selective reflectance imaging technique for enhanced visualization of superficial vasculature. Prior clinical studies have indicated NBI's potential for detection of vasculature abnormalities associated with gastrointestinal mucosal neoplasia. While the basic mechanisms behind the increased vessel contrast - hemoglobin absorption and tissue scattering - are known, a quantitative understanding of the effect of tissue and device parameters has not been achieved. In this investigation, we developed and implemented a numerical model of light propagation that simulates NBI reflectance distributions. This was accomplished by incorporating mucosal tissue layers and vessel-like structures in a voxel-based Monte Carlo algorithm. Epithelial and mucosal layers as well as blood vessels were defined using wavelength-specific optical properties. The model was implemented to calculate reflectance distributions and vessel contrast values as a function of vessel depth (0.05 to 0.50 mm) and diameter (0.01 to 0.10 mm). These relationships were determined for NBI wavelengths of 410 nm and 540 nm, as well as broadband illumination common to standard endoscopic imaging. The effects of illumination bandwidth on vessel contrast were also simulated. Our results provide a quantitative analysis of the effect of absorption and scattering on vessel contrast. Additional insights and potential approaches for improving NBI system contrast are discussed.

  20. Polyp Detection, Characterization, and Management Using Narrow-Band Imaging with/without Magnification

    PubMed Central

    Utsumi, Takahiro; Iwatate, Mineo; Sano, Wataru; Sunakawa, Hironori; Hattori, Santa; Hasuike, Noriaki; Sano, Yasushi

    2015-01-01

    Narrow-band imaging (NBI) is a new imaging technology that was developed in 2006 and has since spread worldwide. Because of its convenience, NBI has been replacing the role of chromoendoscopy. Here we review the efficacy of NBI with/without magnification for detection, characterization, and management of colorectal polyps, and future perspectives for the technology, including education. Recent studies have shown that the next-generation NBI system can detect significantly more colonic polyps than white light imaging, suggesting that NBI may become the modality of choice from the beginning of screening. The capillary pattern revealed by NBI, and the NBI International Colorectal Endoscopic classification are helpful for prediction of histology and for estimating the depth of invasion of colorectal cancer. However, NBI with magnifying colonoscopy is not superior to magnifying chromoendoscopy for estimation of invasion depth. Currently, therefore, chromoendoscopy should also be performed additionally if deep submucosal invasive cancer is suspected. If endoscopists become able to accurately estimate colorectal polyp pathology using NBI, this will allow adenomatous polyps to be resected and discarded; thus, reducing both the risk of polypectomy and costs. In order to achieve this goal, a suitable system for education and training in in vivo diagnostics will be necessary. PMID:26668794

  1. Clinical Application of Magnifying Endoscopy with Narrow-Band Imaging in the Stomach

    PubMed Central

    Yao, Kenshi

    2015-01-01

    Magnifying endoscopy with narrow-band imaging (M-NBI) can visualize superficial microanatomies in the stomach. The normal morphology of the microanatomy visualized by M-NBI differs according to the part of the stomach. The gastric fundic glandular mucosa appears as a regular honeycomb-like subepithelial capillary network (SECN) pattern with a regular collecting venule pattern and regular oval crypt opening with circular marginal crypt epithelium (MCE) pattern. The gastric pyloric glandular mucosa displays a regular coil-shaped SECN pattern and regular polygonal or curved MCE pattern. For a diagnosis of early gastric cancer using M-NBI, the vessel plus surface classification system was developed. This system is clinically useful for the differential diagnosis of focal gastritis and small depressed cancer and for determining the horizontal extent of early gastric cancer for successful endoscopic resection. Advantages of M-NBI over conventional endoscopic imaging techniques with white light include accurate diagnosis and cost effectiveness. This technique is a breakthrough in the endoscopic diagnostic field. PMID:26668793

  2. Development of inexpensive optical broad- and narrow-band sensors for ecosystem research

    NASA Astrophysics Data System (ADS)

    Mollenhauer, Hannes; Cuntz, Thomas; Bumberger, Jan

    2014-05-01

    The observation and monitoring of ecosystem processes are great challenges in environmental science, due to the dynamic and complexity of such procedures. To describe and understand biotic and abiotic processes and their interaction it is necessary to acquire multiple parameters, which are influencing the natural regime. Essential issues are: the detection of spatial heterogeneities and scale overlapping procedures in the environment. To overcome these problems an adequate monitoring system should cover a representative area as well as have a sufficient resolution in time and space. Hence, the needed quantity of sensors (depending on the observed parameters or processes) can be enormous. According to these issues, there is a high demand on low-cost sensor technologies (with adequate performances) to realize a delicate monitoring platform. In the case of vegetation processes, one key feature is to characterize photosynthetic activity of the plants in detail. Common investigation methods are based on optical measurements. Here photosynthetically active radiation (PAR) sensors and hyperspectral sensors are in major use. Photosynthetically active radiation (solar radiation from 400 to 700 nanometers) designates the spectral range that photosynthetic organisms are able to use in the process of photosynthesis. PAR sensors enable the detection of the reflected solar light of the vegetation in whole the PAR wave band. The amount of absorption indicates photosynthetic activity of the plant. Hyperspectral sensors observe specific parts of the solar light spectrum and facilitate the determination of the main pigment classes (Chlorophyll, Carotenoid and Anthocyanin). Due to absorption of pigments they producing a specific spectral signature in the visible part of the electromagnetic spectrum (narrow-band peaks). If vegetation is affected by water or nutritional deficience the proportion of light-absorbing pigments is reduced which finally results in an overall reduced light absorption. The resulting spectral signature then differs from usual reflectance patterns and can be used as stress indicator. Hence, reflectances between 550-700 nm are extremely sensitive regarding changing Chlorophyll contents. Both kinds of sensors based on semiconductor technologies whereby the material input can kept on low level. This work presents the development and testing of a practical, rugged, and inexpensive PAR and hyperspectral sensor. The sensors were made from a gallium arsenide phosphide (GaAsP) photodiodes and silicon photodiodes with different interference filters. First results of recorded long term in-situ data and linear regressions (in comparison to commercial products) show extremely high performances (coefficient of determination higher than 0.99) of the PAR sensors simultaneous to the cost cutting.

  3. Assessing the temperature dependence of narrow-band Raman water vapor lidar measurements: a practical approach.

    PubMed

    Whiteman, David N; Venable, Demetrius D; Walker, Monique; Cadirola, Martin; Sakai, Tetsu; Veselovskii, Igor

    2013-08-01

    Narrow-band detection of the Raman water vapor spectrum using the lidar technique introduces a concern over the temperature dependence of the Raman spectrum. Various groups have addressed this issue either by trying to minimize the temperature dependence to the point where it can be ignored or by correcting for whatever degree of temperature dependence exists. The traditional technique for performing either of these entails accurately measuring both the laser output wavelength and the water vapor spectral passband with combined uncertainty of approximately 0.01 nm. However, uncertainty in interference filter center wavelengths and laser output wavelengths can be this large or larger. These combined uncertainties translate into uncertainties in the magnitude of the temperature dependence of the Raman lidar water vapor measurement of 3% or more. We present here an alternate approach for accurately determining the temperature dependence of the Raman lidar water vapor measurement. This alternate approach entails acquiring sequential atmospheric profiles using the lidar while scanning the channel passband across portions of the Raman water vapor Q-branch. This scanning is accomplished either by tilt-tuning an interference filter or by scanning the output of a spectrometer. Through this process a peak in the transmitted intensity can be discerned in a manner that defines the spectral location of the channel passband with respect to the laser output wavelength to much higher accuracy than that achieved with standard laboratory techniques. Given the peak of the water vapor signal intensity curve, determined using the techniques described here, and an approximate knowledge of atmospheric temperature, the temperature dependence of a given Raman lidar profile can be determined with accuracy of 0.5% or better. A Mathematica notebook that demonstrates the calculations used here is available from the lead author. PMID:23913054

  4. Interpreting motion and force for narrow-band intermodulation atomic force microscopy.

    PubMed

    Platz, Daniel; Forchheimer, Daniel; Tholén, Erik A; Haviland, David B

    2013-01-01

    Intermodulation atomic force microscopy (ImAFM) is a mode of dynamic atomic force microscopy that probes the nonlinear tip-surface force by measurement of the mixing of multiple modes in a frequency comb. A high-quality factor cantilever resonance and a suitable drive comb will result in tip motion described by a narrow-band frequency comb. We show, by a separation of time scales, that such motion is equivalent to rapid oscillations at the cantilever resonance with a slow amplitude and phase or frequency modulation. With this time-domain perspective, we analyze single oscillation cycles in ImAFM to extract the Fourier components of the tip-surface force that are in-phase with the tip motion (F(I)) and quadrature to the motion (F(Q)). Traditionally, these force components have been considered as a function of the static-probe height only. Here we show that F(I) and F(Q) actually depend on both static-probe height and oscillation amplitude. We demonstrate on simulated data how to reconstruct the amplitude dependence of F(I) and F(Q) from a single ImAFM measurement. Furthermore, we introduce ImAFM approach measurements with which we reconstruct the full amplitude and probe-height dependence of the force components F(I) and F(Q), providing deeper insight into the tip-surface interaction. We demonstrate the capabilities of ImAFM approach measurements on a polystyrene polymer surface. PMID:23400552

  5. Narrow band ultraviolet B irradiations cause alteration in interleukin-31 serum level in psoriatic patients.

    PubMed

    Narbutt, Joanna; Olejniczak, Irmina; Sobolewska-Sztychny, Dorota; Sysa-Jedrzejowska, Anna; S?owik-Kwiatkowska, Iwona; Hawro, Tomasz; Lesiak, Aleksandra

    2013-04-01

    Scientific communications indicate the disturbed expression of neuropeptides in the skin and serum in psoriasis vulgaris (PsV) patients. Narrow-band ultraviolet radiation (NB-UVB) is one of the systemic therapies of PsV. The aim of the study was to evaluate the influence of NB-UVB therapy on substance P (SP), calcitonin gene-related peptide (CGRP), brain-derived neurotrophic factor (BDNF), corticotropin-releasing factor (CRF) and interleukin-31 (IL-31) serum concentrations in PsV patients. 59 psoriatic patients with mean PASI (psoriasis area and severity index) 14.3 were treated with NB-UVB (20 exposures). The control group consisted of 50 healthy subjects, whose age and sex matched. In all patients, serum concentration of BDNF, CRF, IL-31 substance P and CGRP was analyzed by ELISA before the treatment and in psoriatic group the analysis was also done after 10 and 20 irradiations. In patients there was found a significantly higher concentration of IL-31 (215.3 vs. 748.6 ng/ml; p < 0.0001), SP (25.7 vs. 67.2 pg/ml; p < 0.01), CGRP (31.4 vs. 44.15 pg/ml; p < 0.01) and a lower concentration of CRF (0.89 vs. 0.426 ng/ml; p < 0.0001) and BDNF (16.39 vs. 14.15 ng/ml; p = 0.1216) in comparison with the controls. 20 NB-UVB exposures caused a significant decrease in IL-31 level (748.6 vs. 631.7 ng/ml; p < 0.0001). The NB-UVB therapy had no major effect on neuropeptides serum levels regardless of a number of irradiations. On the basis of our study it can be suggested that IL-31 is involved in pathogenesis of psoriasis and the NB-UVB therapy causes alterations in its level. PMID:23108364

  6. Narrow-band imaging for the computer assisted diagnosis in patients with Barrett's esophagus

    NASA Astrophysics Data System (ADS)

    Kage, Andreas; Raithel, Martin; Zopf, Steffen; Wittenberg, Thomas; Münzenmayer, Christian

    2009-02-01

    Cancer of the esophagus has the worst prediction of all known cancers in Germany. The early detection of suspicious changes in the esophagus allows therapies that can prevent the cancer. Barrett's esophagus is a premalignant change of the esophagus that is a strong indication for cancer. Therefore there is a big interest to detect Barrett's esophagus as early as possible. The standard examination is done with a videoscope where the physician checks the esophagus for suspicious regions. Once a suspicious region is found, the physician takes a biopsy of that region to get a histological result of it. Besides the traditional white light for the illumination there is a new technology: the so called narrow-band Imaging (NBI). This technology uses a smaller spectrum of the visible light to highlight the scene captured by the videoscope. Medical studies indicate that the use of NBI instead of white light can increase the rate of correct diagnoses of a physician. In the future, Computer-Assisted Diagnosis (CAD) which is well known in the area of mammography might be used to support the physician in the diagnosis of different lesions in the esophagus. A knowledge-based system which uses a database is a possible solution for this task. For our work we have collected NBI images containing 326 Regions of Interest (ROI) of three typical classes: epithelium, cardia mucosa and Barrett's esophagus. We then used standard texture analysis features like those proposed by Haralick, Chen, Gabor and Unser to extract features from every ROI. The performance of the classification was evaluated with a classifier using the leaving-one-out sampling. The best result that was achieved is an accuracy of 92% for all classes and an accuracy of 76% for Barrett's esophagus. These results show that the NBI technology can provide a good diagnosis support when used in a CAD system.

  7. Detection of Mucosal Recurrent Nasopharyngeal Carcinomas After Radiotherapy With Narrow-Band Imaging Endoscopy

    SciTech Connect

    Wang, Wen-Hung; Lin, Yen-Chun; Chen, Wen-Cheng; Chen, Miao-Fen; Chen, Chih-Cheng; Lee, Kam-Fai

    2012-07-15

    Purpose: This study evaluated the feasibility of screening mucosal recurrent nasopharyngeal carcinoma with narrow-band imaging (NBI) endoscopy. Methods and Materials: One hundred and six patients were enrolled. All patients underwent conventional white-light (WL) endoscopic examination of the nasopharynx followed by NBI endoscopy. Biopsies were performed if recurrence was suspected. Results: We identified 32 suspected lesions by endoscopy in WL and/or NBI mode. Scattered brown spots (BS) were identified in 22 patients, and 4 of the 22 who had negative MRI findings were histopathologically confirmed to be neoplasias that were successfully removed via endoscopy. A comparison of the visualization in NBI closer view corresponded to histopathological findings in 22 BS, and the prevalence rates of neoplasias in tail signs, round signs, and irregularities signs were 0% (0/6), 0% (0/7), and 44.4% (4/9), respectively (p = 0.048). The sensitivity, specificity, and diagnostic capability were 37.5%, 92.9% and 0.652 for WL, 87.5%, 74.5% and 0.810 for NBI, and 87.5%, 87.8%, and 0.876 for NBI closer view, respectively. NBI closer view was effective in increasing specificity compared with NBI alone (87.8% vs. 74.5%, p < 0.05), and in increasing sensitivity and diagnostic capability compared to WL alone (87.5% vs. 37.5%, p < 0.05; 0.876 vs. 0.652, p = 0.0001). Conclusions: Although NBI in endoscopy can improve sensitivity of mucosal recurrent nasopharyngeal neoplasias, false-positive (nonneoplasia BS) results may be obtained in areas with nonspecific inflammatory changes due to postradiation effects. NBI closer view not only can offer a timely, convenient, and highly reliable assessment of mucosal recurrent nasopharyngeal carcinoma, it can also make endoscopic removal possible.

  8. Assessing the Temperature Dependence of Narrow-Band Raman Water Vapor Lidar Measurements: A Practical Approach

    NASA Technical Reports Server (NTRS)

    Whiteman, David N.; Venable, Demetrius D.; Walker, Monique; Cardirola, Martin; Sakai, Tetsu; Veselovskii, Igor

    2013-01-01

    Narrow-band detection of the Raman water vapor spectrum using the lidar technique introduces a concern over the temperature dependence of the Raman spectrum. Various groups have addressed this issue either by trying to minimize the temperature dependence to the point where it can be ignored or by correcting for whatever degree of temperature dependence exists. The traditional technique for performing either of these entails accurately measuring both the laser output wavelength and the water vapor spectral passband with combined uncertainty of approximately 0.01 nm. However, uncertainty in interference filter center wavelengths and laser output wavelengths can be this large or larger. These combined uncertainties translate into uncertainties in the magnitude of the temperature dependence of the Raman lidar water vapor measurement of 3% or more. We present here an alternate approach for accurately determining the temperature dependence of the Raman lidar water vapor measurement. This alternate approach entails acquiring sequential atmospheric profiles using the lidar while scanning the channel passband across portions of the Raman water vapor Q-branch. This scanning is accomplished either by tilt-tuning an interference filter or by scanning the output of a spectrometer. Through this process a peak in the transmitted intensity can be discerned in a manner that defines the spectral location of the channel passband with respect to the laser output wavelength to much higher accuracy than that achieved with standard laboratory techniques. Given the peak of the water vapor signal intensity curve, determined using the techniques described here, and an approximate knowledge of atmospheric temperature, the temperature dependence of a given Raman lidar profile can be determined with accuracy of 0.5% or better. A Mathematica notebook that demonstrates the calculations used here is available from the lead author.

  9. Advantage of transurethral resection with narrow band imaging for non-muscle invasive bladder cancer

    PubMed Central

    KOBATAKE, KOHEI; MITA, KOJI; OHARA, SHINYA; KATO, MASAO

    2015-01-01

    The aim of the present study was to compare the benefits of transurethral resection (TUR) under narrow band imaging (NBI-TUR) and TUR under conventional white light imaging (WLI-TUR) for non-muscle invasive bladder cancer (NMIBC). The study cohort consisted of 135 patients with NMIBC who were followed up for ?1 year after TUR and who received no additional post-operative treatment. In the WLI-TUR group (n=78), systematic intravesical observation under WLI was followed by a multiple site biopsy (MSB), after which lesions detected as positive findings were resected completely under WLI. In the NBI-TUR group (n=57), similar observation under WLI was followed by systematic intravesical observation under NBI. Following MSB under NBI, TUR was performed for all lesions detected as positive findings under NBI. The sensitivity, specificity, positive-predictive value, negative-predictive value (NPV) and accuracy in the NBI-TUR group were calculated using results from the cystoscopical and pathological examinations of MSB samples under WLI and NBI. The tumor recurrence rate was analyzed in the two groups. Background factors did not differ significantly between the two groups, with the exception of the observation period (31.0 vs. 15.0 months; P<0.01). The procedure under NBI exhibited significantly higher sensitivity (95.0 vs. 70.0%; P<0.01) and NPV (97.1 vs. 86.8%; P<0.01) compared with the procedure under WLI. The 1-year recurrence rate in the NBI-TUR group was significantly lower than that in the WLI-TUR group (21.1 vs. 39.7%; P=0.016). In conclusion, the present study indicated that NBI-TUR is more advantageous than conventional WLI-TUR for patients with NMIBC.

  10. Endocytoscopic narrow-band imaging efficiency for evaluation of inflammatory activity in ulcerative colitis

    PubMed Central

    Maeda, Yasuharu; Ohtsuka, Kazuo; Kudo, Shin-ei; Wakamura, Kunihiko; Mori, Yuichi; Ogata, Noriyuki; Wada, Yoshiki; Misawa, Masashi; Yamauchi, Akihiro; Hayashi, Seiko; Kudo, Toyoki; Hayashi, Takemasa; Miyachi, Hideyuki; Yamamura, Fuyuhiko; Ishida, Fumio; Inoue, Haruhiro; Hamatani, Shigeharu

    2015-01-01

    AIM: To assess the efficacy of endocytoscopic narrow-band imaging (EC-NBI) for evaluating the severity of inflammation in ulcerative colitis (UC). METHODS: This retrospective study was conducted at a single tertiary care referral center. We included UC patients who underwent colonoscopy with endocytoscopy from July 2010 to December 2013. EC-NBI was performed, and the images were evaluated by assessing visibility, increased vascularization, and the increased calibers of capillaries and were classified as Obscure, Visible or Dilated. Obscure was indicative of inactive disease, while Visible and Dilated were indicative of acute inflammation. This study received Institutional Review Board approval. The primary outcome measures included the diagnostic ability of EC-NBI to distinguish between active and inactive UC on the basis of histological activity. The conventional endoscopic images were classified according to the Mayo endoscopic score. A score of 0 or 1 indicated inactive disease, whereas a score of 2 indicated active disease. RESULTS: Fifty-two patients were enrolled. There was a strong correlation between the EC-NBI findings and the histological assessment (r = 0.871, P < 0.01). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of EC-NBI for diagnosing acute inflammation were 84.0%, 100%, 87.1%, 100%, and 92.3%, respectively, while those for the Mayo endoscopic score were 100%, 40.7%, 100%, 61.0%, and 69.2%, respectively. Compared with conventional endoscopy, EC-NBI was superior in diagnostic specificity, negative predictive value, and accuracy (P < 0.001, P = 0.001 and P = 0.047, respectively). CONCLUSION: The EC-NBI finding of capillaries in the rectal mucosa was strongly correlated with histological inflammation and aided in the differential diagnosis between active and inactive UC. PMID:25717245

  11. Simplified Classification of Capillary Pattern in Barrett Esophagus Using Magnifying Endoscopy With Narrow Band Imaging

    PubMed Central

    Uno, Goichi; Ishimura, Norihisa; Tada, Yasumasa; Tamagawa, Yuji; Yuki, Takafumi; Matsushita, Takashi; Ishihara, Shunji; Amano, Yuji; Maruyama, Riruke; Kinoshita, Yoshikazu

    2015-01-01

    Abstract The classification of Barrett esophagus (BE) using magnifying endoscopy with narrow band imaging (ME-NBI) is not widely used in clinical settings because of its complexity. To establish a new simplified available classification using ME-NBI. We conducted a cross-sectional study in a single-referral center. One hundred eight consecutive patients with BE using ME-NBI and crystal violet (CV) chromoendoscopy, and histological findings were enrolled. BE areas observed by ME-NBI were classified as type I or II on the basis of capillary pattern (CP), and as closed or open type on the basis of a mucosal pit pattern using CV chromoendoscopy; then, biopsy samples were obtained. We evaluated the relation between CP and pit pattern, expression of the factors with malignant potential, percentage of microvascular density, and interobserver agreement. One hundred thirty lesions from 91 patients were analyzed. Type II CP had more open type pit pattern areas and significantly greater microvascular density than type I. The presence of dysplasia, specialized intestinal metaplasia, expressions of COX-2, CDX2, and CD34, and PCNA index were significantly higher in type II, whereas the multivariate analysis showed that type II was the best predictor for the presence of dysplasia (OR 11.14), CD34 expression (OR 3.60), and PCNA (OR 3.29). Interobserver agreement for this classification was substantial (??=?0.66). A simplified CP classification based on observation with ME-NBI is presented. Our results indicate that the classification may be useful for surveillance of BE with high malignant potential. PMID:25621687

  12. Narrow-band Imager for Multi-Application Solar Telescope (MAST) at Udaipur Solar Observatory

    NASA Astrophysics Data System (ADS)

    Raja Bayanna, A.; Mathew, Shibu K.; Venkatakrishnan, Parameswaran; Srivastava, Nandita

    2013-04-01

    Multi-Application Solar Telescope (MAST) is an off-axis Gregorian solar telescope of 50 cm clear aperture installed at the lake site of Udaipur solar observatory (USO). A narrow band imager is being developed for near simultaneous observations of the solar atmosphere at different heights. The heart of the system is two Fabry-Perot (FP) etalons working in tandem. The substrate of the etalons is made of Lithium Niobate electro-optic crystal. The filter is tuned by changing the refractive index of the crystal with the application of the voltage. It is important to know the voltage required per unit wavelength shift to tune the system for different wavelength regions for near simultaneous observations. A littrow spectrograph was set up to calibrate the FP etalons. The achieved spectral resolution with the spectrograph at 6173 Å is 35 mÅ. Calibration is carried-out for the Fe I 6173 Å, H-alpha 6563 Å and Ca K 8542 Å. Free spectral range (FSR) obtained for FP1 and FP2 in tandem for 6173 Å is 6.7Å and 150 mÅ respectively. Voltage range of the system allows us to scan the entire line profile of 6173 in the range of ±220 mÅ with a sampling of 20 mÅ. We also performed temperature tuning and voltage tuning of the system. Similar exercise is performed for other two wavelengths. Here we present the details of the calibration set-up and obtained parameters and first-light results of the system.

  13. Competitive behavior of photons contributing to junction voltage jump in narrow band-gap semiconductor multi-quantum-well laser diodes at lasing threshold

    NASA Astrophysics Data System (ADS)

    Feng, Liefeng; Yang, Xiufang; Li, Yang; Li, Ding; Wang, Cunda; Yao, Dongsheng; Hu, Xiaodong; Li, Hongru

    2015-04-01

    The junction behavior of different narrow band-gap multi-quantum-well (MQW) laser diodes (LDs) confirmed that the jump in the junction voltage in the threshold region is a general characteristic of narrow band-gap LDs. The relative change in the 1310 nm LD is the most obvious. To analyze this sudden voltage change, the threshold region is divided into three stages by Ithl and Ithu, as shown in Fig. 2; Ithl is the conventional threshold, and as long as the current is higher than this threshold, lasing exists and the IdV/dI-I plot drops suddenly; Ithu is the steady lasing point, at which the separation of the quasi-Fermi levels of electron and holes across the active region (Vj) is suddenly pinned. Based on the evolutionary model of dissipative structure theory, the rate equations of the photons in a single-mode LD were deduced in detail at Ithl and Ithu. The results proved that the observed behavior of stimulated emission suddenly substituting for spontaneous emission, in a manner similar to biological evolution, must lead to a sudden increase in the injection carriers in the threshold region, which then causes the sudden increase in the junction voltage in this region.

  14. Photonic band-edge-induced enhancement in absorption and emission

    NASA Astrophysics Data System (ADS)

    Ummer, Karikkuzhi Variyath; Vijaya, Ramarao

    2015-01-01

    An enhancement in photonic band-edge-induced absorption and emission from rhodamine-B dye doped polystyrene pseudo gap photonic crystals is studied. The band-edge-induced enhancement in absorption is achieved by selecting the incident angle of the excitation beam so that the absorption spectrum of the emitter overlaps the photonic band edge. The band-edge-induced enhancement in emission, on the other hand, is possible with and without an enhancement in band-edge-induced absorption, depending on the collection angle of emission. Through a simple set of measurements with suitably chosen angles for excitation and emission, we achieve a maximum enhancement of 70% in emission intensity with band-edge-induced effects over and above the intrinsic emission in the case of self-assembled opals. This is a comprehensive effort to interpret tunable lasing in opals as well as to predict the wavelength of lasing arising as a result of band-edge-induced distributed feedback effects.

  15. AVHRR Surface Temperature and Narrow-Band Albedo Comparison with Ground Measurements for the Greenland Ice Sheet

    NASA Technical Reports Server (NTRS)

    Haefliger, M.; Steffen, K.; Fowler, C.

    1993-01-01

    An ice-surface temperature retrieval algorithm for the Greenland ice sheet was developed using NOAA 11 thermal radiances from channels 4 and 5. Temperature, pressure and humidity profiles, cloud observations and skin temperatures from the Swiss Federal Institute of Technology (ETH) camp, located at the equilibrium line altitude at 49 deg17 min W, 69 deg 34 min N, were used in the LOWTRAN 7 model. Through a statistical analysis of daily clear sky profiles, the coefficients that correct for the atmospheric effects were determined for the ETH-Camp field season (May to August). Surface temperatures retrieved by this method were then compared against the in situ observations with a maximum difference of 0.6 K. The NOAA 11 narrow-band planetary albedo values for channels 1 and 2 were calculated using pre-launch calibration coefficients. Scattering and absorption by the atmosphere were modelled with LOWTRAN 7. Then, narrow-band albedo values for the AVHRR visible and near infrared channels were compared with in situ high resolution spectral reflectance measurements. In the visible band (580-680 nm), AVHRR-derived narrow-band albedo and the in situ measurements corrected with radiative transfer model LOWTRAN 7 showed a difference of less than 2%. For the near infrared channel (725-1100 nm) the difference between the measured and modelled narrow-band albedo was 14%. These discrepancies could be either the result of inaccurate aerosol scattering modelling (lack of the in situ observation), or the result of sensor drift due to degradation.

  16. An inexpensive S-band angle pointing technique for steering a narrow beam Ku-band antenna

    NASA Technical Reports Server (NTRS)

    Line, Larry; Hager, Fred; Hanson, Duke; Kral, Kevin; Moss, Robert

    1987-01-01

    A recently tested antenna pointing control system for gimbaled antennas has been developed. A modified TDRSS user transponder produces pointing error signals from the S-band forward link which in turn drive the Steering Control Electronics (SCE) to precision steer a S-/Ku-band Data and S-band Tracking (KDST) planar array. A successful test of the pointing and data handling capabilities is described and plans for further tests, incorporating additional refinements, are presented.

  17. Design of narrow bandwidth ladder-type filters with sharp transition bands using mutually connected resonator elements.

    PubMed

    Komatsu, Tomoya; Tanaka, Yasutomo; Hashimoto, Ken-ya; Omori, Tatsuya; Yamaguchi, Masatsune

    2009-07-01

    This paper proposes a new design technique for a ladder-type filter to reduce the passband width without sacrificing the insertion loss, out-of-band rejection, and steepness of the transition bands. First, it is shown that 2 transmission zeros can be generated by connecting an additional resonator in either series or parallel arm of the ladder filter topology. This new filter topology can be designed systematically by the derived-m transformation. Second, it is demonstrated that the narrow bandwidth, sharp transition bands, and large out-of- band rejection are simultaneously realized by applying the present technique to specifically designed ladder-type filters. Finally, this technique is applied to the design of a SAW filter fabricated on the Cu-grating/15 degrees YX-LiNbO3 structure. PMID:19574155

  18. A narrow band-pass filter type Wilkinson power divider for I-Q demodulator in microwave interferometer system

    NASA Astrophysics Data System (ADS)

    Wang, X.; Yoshikawa, M.; Kohagura, J.; Shima, Y.; Ikezoe, R.; Sakamoto, M.; Imai, T.; Nakashima, Y.; Ma, Z.; Sakagami, I.; Mase, A.

    2015-11-01

    I-Q (In-phase Quadrature) demodulator is one of key components in microwave interferometer system application. Normally, I-Q demodulator consists of amplifiers, mixers, 90 degree phase shifter, power divider and band-pass filters, and it is widely used in various microwave communication systems and measurement systems. In this paper, power divider and band-pass filters are newly designed as one single passive component, therefore, I-Q demodulator topology becomes simplified. The novel narrow band-pass filter type Wilkinson power divider not only provides extremely miniaturized circuit size, but also maintains the band-pass filter performance and power division function as well. One experimental circuit shows good agreement with the theoretical simulation.

  19. [Elimination on Power Line Interference from ECG Signal Using Combined Double-sided Narrow-band Notch Filter].

    PubMed

    Zaitsev, E V

    2015-01-01

    The aim of current research was to find negative effects caused by eliminating power line interference in ECG signal with narrow-band recursive notch filter and to search for a filtering method that will solve a problem of signal distortion. During the study the method of ECG filtering with narrow-band recursive filter was described. The main negative attribute of this filter is a transient noise, also called "ringing" effect, as the reaction to a single impulse visible as R spikes on the ECG signals. It was discovered, that "ringing" effect appears after the impulse during forward filtering and before the impulse during backward filtering. Based on this effect we proposed a method the main idea of which was to build the finite signal with regions without transients. PMID:26394480

  20. Optimization of advanced Wiener estimation methods for Raman reconstruction from narrow-band measurements in the presence of fluorescence background

    PubMed Central

    Chen, Shuo; Ong, Yi Hong; Lin, Xiaoqian; Liu, Quan

    2015-01-01

    Raman spectroscopy has shown great potential in biomedical applications. However, intrinsically weak Raman signals cause slow data acquisition especially in Raman imaging. This problem can be overcome by narrow-band Raman imaging followed by spectral reconstruction. Our previous study has shown that Raman spectra free of fluorescence background can be reconstructed from narrow-band Raman measurements using traditional Wiener estimation. However, fluorescence-free Raman spectra are only available from those sophisticated Raman setups capable of fluorescence suppression. The reconstruction of Raman spectra with fluorescence background from narrow-band measurements is much more challenging due to the significant variation in fluorescence background. In this study, two advanced Wiener estimation methods, i.e. modified Wiener estimation and sequential weighted Wiener estimation, were optimized to achieve this goal. Both spontaneous Raman spectra and surface enhanced Raman spectra were evaluated. Compared with traditional Wiener estimation, two advanced methods showed significant improvement in the reconstruction of spontaneous Raman spectra. However, traditional Wiener estimation can work as effectively as the advanced methods for SERS spectra but much faster. The wise selection of these methods would enable accurate Raman reconstruction in a simple Raman setup without the function of fluorescence suppression for fast Raman imaging. PMID:26203387

  1. Optimization of advanced Wiener estimation methods for Raman reconstruction from narrow-band measurements in the presence of fluorescence background.

    PubMed

    Chen, Shuo; Ong, Yi Hong; Lin, Xiaoqian; Liu, Quan

    2015-07-01

    Raman spectroscopy has shown great potential in biomedical applications. However, intrinsically weak Raman signals cause slow data acquisition especially in Raman imaging. This problem can be overcome by narrow-band Raman imaging followed by spectral reconstruction. Our previous study has shown that Raman spectra free of fluorescence background can be reconstructed from narrow-band Raman measurements using traditional Wiener estimation. However, fluorescence-free Raman spectra are only available from those sophisticated Raman setups capable of fluorescence suppression. The reconstruction of Raman spectra with fluorescence background from narrow-band measurements is much more challenging due to the significant variation in fluorescence background. In this study, two advanced Wiener estimation methods, i.e. modified Wiener estimation and sequential weighted Wiener estimation, were optimized to achieve this goal. Both spontaneous Raman spectra and surface enhanced Raman spectra were evaluated. Compared with traditional Wiener estimation, two advanced methods showed significant improvement in the reconstruction of spontaneous Raman spectra. However, traditional Wiener estimation can work as effectively as the advanced methods for SERS spectra but much faster. The wise selection of these methods would enable accurate Raman reconstruction in a simple Raman setup without the function of fluorescence suppression for fast Raman imaging. PMID:26203387

  2. Magnifying narrow-band imaging endoscopy is superior in diagnosis of early gastric cancer

    PubMed Central

    Yu, Hang; Yang, Ai-Ming; Lu, Xing-Hua; Zhou, Wei-Xun; Yao, Fang; Fei, Gui-Jun; Guo, Tao; Yao, Li-Qing; He, Li-Ping; Wang, Bang-Mao

    2015-01-01

    AIM: To evaluate the diagnostic effectiveness of white light endoscopy, magnifying endoscopy (ME), and magnifying narrow-band imaging endoscopy (ME-NBI) in detecting early gastric cancer (EGC). METHODS: From March 2010 to June 2012, a total of 3616 patients received screening for gastric cancer by magnifying endoscopy. There were 3675 focal gastric lesions detected using conventional high definition white light endoscopy (HD-WLE) in four different referential hospitals that were recruited for further investigation using ME and ME-NBI. The images obtained from HD-WLE, ME, and ME-NBI were reviewed by four experienced endoscopists to evaluate their diagnostic effectiveness for EGC. The diagnosis of cancerous and non-cancerous lesions was conducted by evaluating the microvascular and microsurface patterns using the VS classification system. The final endoscopic diagnosis of each lesion was determined by consultation when a disagreement occurred. We used histopathological results as the gold standard for the diagnosis of EGC. RESULTS: Among the 3675 lesions found, 1508 were validated by pathological findings as chronic gastritis, 1279 as chronic gastritis with intestinal metaplasia, 631 as low-grade neoplasia, and 257 as EGC. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of HD-WLE for the diagnosis of EGC were 71.2%, 99.1%, 85.5%, 97.9% and 97.1%, respectively. The results of ME for diagnosing EGC were 81.3%, 98.8%, 83.3%, 98.6% and 97.6%, respectively. The results of ME-NBI for the diagnosis of EGC were 87.2%, 98.6%, 82.1%, 99.0% and 97.8%, respectively. The diagnostic sensitivity and accuracy of paired ME and ME-NBI were significantly better than those of HD-WLE (P < 0.05). CONCLUSION: HD-WLE has a relatively high accuracy for diagnosing EGC and is an effective screening tool. Further investigations of ME and ME-NBI are required to achieve superior accuracy. PMID:26290643

  3. Diagnostic performance of magnifying narrow-band imaging for early gastric cancer: A meta-analysis

    PubMed Central

    Hu, Ying-Ying; Lian, Qing-Wu; Lin, Zheng-Hua; Zhong, Jing; Xue, Meng; Wang, Liang-Jing

    2015-01-01

    AIM: To investigate the performance of magnifying endoscopy with narrow-band imaging (ME-NBI) in the diagnosis of early gastric cancer (EGC). METHODS: Systematic literature searches were conducted until February 2014 in PubMed, EMBASE, Web of Science, Ovid, Scopus and the Cochrane Library databases by two independent reviewers. Meta-analysis was performed to calculate the pooled sensitivity, specificity and diagnostic odds ratio and to construct a summary receiver operating characteristic (ROC) curve. Subgroup analyses were performed based on the morphology type of lesions, diagnostic standard, the size of lesions, type of assessment, country and sample size to explore possible sources of heterogeneity. A Deeks’ asymmetry test was used to evaluate the publication bias. RESULTS: Fourteen studies enrolling 2171 patients were included. The pooled sensitivity, specificity and diagnostic odds ratio for ME-NBI diagnosis of EGC were 0.86 (95%CI: 0.83-0.89), 0.96 (95%CI: 0.95-0.97) and 102.75 (95%CI: 48.14-219.32), respectively, with the area under ROC curve being 0.9623. Among the 14 studies, six also evaluated the diagnostic value of conventional white-light imaging, with a sensitivity of 0.57 (95%CI: 0.50-0.64) and a specificity of 0.79 (95%CI: 0.76-0.81). When using “VS” (vessel plus surface) ME-NBI diagnostic systems in gastric lesions of depressed macroscopic type, the pooled sensitivity and specificity were 0.64 (95%CI: 0.52-0.75) and 0.96 (95%CI: 0.95-0.98). For the lesions with a diameter less than 10 mm, the sensitivity and specificity were 0.74 (95%CI: 0.65-0.82) and 0.98 (95%CI: 0.97-0.98). CONCLUSION: ME-NBI is a promising endoscopic tool in the diagnosis of early gastric cancer and might be helpful in further target biopsy. PMID:26167089

  4. Spectrally narrowed emissions from organic crystals mounted on transfer-printed parylene diffraction gratings

    NASA Astrophysics Data System (ADS)

    Fukaya, Yoshihide; Obama, Yuki; Hotta, Shu; Yamao, Takeshi

    2014-01-01

    We have fabricated diffraction gratings of parylene by evaporation polymerization. The parylene film was deposited onto a commercially available diffraction grating used as a template and transfer-printed onto a substrate. A well-defined periodic structure was replicated on the parylene film surface and its period was in good agreement with that of the template. For future light-emitting device application, we laminated a parylene grating with organic semiconductor crystals and investigated their emission properties under weak ultraviolet light excitation. We observed emissions parallel to the grating wave vector. Their spectra narrowed as peaks with full-widths at half-maxima less than 5 nm. We discussed these narrow emission lines considering them as the propagating light in a waveguide composed of the organic crystal and parylene grating. The present results reflect the formation of a high-quality optical cavity on a parylene film.

  5. Band limited emission with central frequency around 2 Hz accompanying powerful cyclones

    NASA Technical Reports Server (NTRS)

    Troitskaia, V. A.; Shepetnov, K. S.; Dvobnia, B. D.

    1992-01-01

    It has been found that powerful cyclones are proceeded, accompanied and followed by narrow band electromagnetic emission with central frequency around 2 Hz. It is shown that the signal from this emission is unique and clearly distinguishable from known types of magnetic pulsations, spectra of local thunderstorms, and signals from industrial sources. This emission was first observed during an unusually powerful cyclone with tornadoes in the western European part of the Soviet Union, which passed by the observatory of Borok from south to north-east. The emission has been confirmed by analysis of similar events in Antarctica. The phenomenon described presents a new aspect of interactions of processes in the lower atmosphere and the ionosphere.

  6. Diagnosis of gastric intraepithelial neoplasia by narrow-band imaging and confocal laser endomicroscopy

    PubMed Central

    Wang, Shu-Fang; Yang, Yun-Sheng; Wei, Li-Xin; Lu, Zhong-Sheng; Guo, Ming-Zhou; Huang, Jin; Peng, Li-Hua; Sun, Gang; Ling-Hu, En-Qiang; Meng, Jiang-Yun

    2012-01-01

    AIM: To evaluate the diagnosis of different differentiated gastric intraepithelial neoplasia (IN) by magnification endoscopy combined with narrow-band imaging (ME-NBI) and confocal laser endomicroscopy (CLE). METHODS: Eligible patients with suspected gastric IN lesions previously diagnosed by endoscopy in secondary hospitals and scheduled for further diagnosis and treatment were recruited for this study. Excluded from the study were patients who had liver cirrhosis, impaired renal function, acute gastrointestinal (GI) bleeding, coagulopathy, esophageal varices, jaundice, and GI post-surgery. Also excluded were those who were pregnant, breastfeeding, were younger than 18 years old, or were unable to provide informed consent. All patients had all mucus and bile cleared from their stomachs. They then received upper GI endoscopy. When a mucosal lesion is found during observation with white-light imaging, the lesion is visualized using maximal magnification, employing gradual movement of the tip of the endoscope to bring the image into focus. Saved images are analyzed. Confocal images were evaluated by two endoscopists (Huang J and Li MY), who were familiar with CLE, blinded to the related information about the lesions, and asked to classify each lesion as either a low grade dysplasia (LGD) or high grade dysplasia (HGD) according to given criteria. The results were compared with the final histopathologic diagnosis. ME-NBI images were evaluated by two endoscopists (Lu ZS and Ling-Hu EQ) who were familiar with NBI, blinded to the related information about the lesions and CLE images, and were asked to classify each lesion as a LGD or HGD according to the “microvascular pattern and surface pattern” classification system. The results were compared with the final histopathologic diagnosis. RESULTS: The study included 32 pathology-proven low grade gastric IN and 26 pathology-proven high grade gastric IN that were detected with any of the modalities. CLE and ME-NBI enabled clear visualization of the vascular microsurface patterns and microvascular structures of the gastric mucosa. The accuracy of the CLE and the ME-NBI diagnosis was 88% (95% CI: 78%-98%) and 81% (95% CI: 69%-93%), respectively. The kappa coefficient of agreement between the histopathology and the in vivo CLE imaging was 0.755; between the histopathology and the in vivo CLE imaging was 0.615. McNemar’s test (binomial distribution used) indicated that the agreement was significant (P < 0.05). When patients were diagnosed by ME-NBI with CLE, the overall accuracy of the diagnosis was 86.21% (95% CI: 73%-96%), and the kappa coefficient of agreement was 0.713, according to McNemar’s test (P < 0.05). CONCLUSION: Higher diagnostic accuracy, sensitivity and specificity of CLE over ME-NBI indicate the feasibility of these two techniques for the efficacious diagnostic classification of gastric IN. PMID:23002348

  7. SUB-BAND MODELING OF TRANSPORT IN NARROW GEOMETRIES Christian Ringhofer (Arizona State University)

    E-print Network

    Maryland at College Park, University of

    . #12;JOINT WORK WITH N. BenAbdallah, P. Degond (Toulouse) C. Heitzinger (Vienna) Supported by NSF IN NARROW GEOMETRIES ­ p. #12;APPLICATIONS 1 Thin films: Nano-scale logics and analog devices. SOI (Silicon, Diffusion etc.) 1-3: physical transport mechanisms. 4: function of the structure on large time scales. SUB

  8. ALEXIS (Array of Low-Energy X-Ray Imaging Sensors): A narrow-band survey/monitor of the ultrasoft x-ray sky

    SciTech Connect

    Priedhorsky, W.C.; Bloch, J.J.; Cordova, F.; Smith, B.W.; Ulibarri, M.; Chavez, J.; Evans, E.; Seigmund, O.H.W.; Marshall, H.; Vallerga, J.

    1989-01-01

    Los Alamos and Sandia National Laboratories are building an ultrasoft X-ray monitor experiment. This experiment, called ALEXIS (Array of Low-Energy X-Ray Imaging Sensors), consists of six compact normal-incidence telescopes. ALEXIS will operate in the range 70--110 eV. The ultrasoft X-ray/EUV band is nearly uncharted territory for astrophysics. ALEXIS, with its wide fields-of-view and well-defined wavelength bands, will complement the upcoming NASA Extreme Ultraviolet Explorer and ROSAT EUV Wide Field Camera, which are sensitive broad-band survey experiments. The program objectives of ALEXIS are to (1) demonstrate the feasibility of a wide field-of-view, normal incidence ultrasoft X-ray telescope system and (2) to determine ultrasoft X-ray backgrounds in the space environment. As a dividend, ALEXIS will pursue the following scientific objectives: (1) to map the diffuse background, with unprecedented angular resolution, in several emission-line bands, (2) to perform a narrow-band survey of point sources, (3) to search for transient phenomena in the ultrasoft X-ray band, and (4) to provide synoptic monitoring of variable ultrasoft X-ray sources such as cataclysmic variables and flare stars. ALEXIS is designed to be flown on a small autonomous payload carrier (a minisat) that could be launched from any expendable launch vehicle. The experiment weighs 100 pounds, draws 40 watts, and produces 10 kbps of data. It can be flown in any low earth orbit. Onboard data storage allows operation and tracking from a single ground station at Los Alamos. 57 refs., 12 figs.

  9. New Insights on the Burstein-Moss Shift and Band Gap Narrowing in Indium-Doped Zinc Oxide Thin Films.

    PubMed

    Saw, K G; Aznan, N M; Yam, F K; Ng, S S; Pung, S Y

    2015-01-01

    The Burstein-Moss shift and band gap narrowing of sputtered indium-doped zinc oxide (IZO) thin films are investigated as a function of carrier concentrations. The optical band gap shifts below the carrier concentration of 5.61 × 1019 cm-3 are well-described by the Burstein-Moss model. For carrier concentrations higher than 8.71 × 1019 cm-3 the shift decreases, indicating that band gap narrowing mechanisms are increasingly significant and are competing with the Burstein-Moss effect. The incorporation of In causes the resistivity to decrease three orders of magnitude. As the mean-free path of carriers is less than the crystallite size, the resistivity is probably affected by ionized impurities as well as defect scattering mechanisms, but not grain boundary scattering. The c lattice constant as well as film stress is observed to increase in stages with increasing carrier concentration. The asymmetric XPS Zn 2p3/2 peak in the film with the highest carrier concentration of 7.02 × 1020 cm-3 suggests the presence of stacking defects in the ZnO lattice. The Raman peak at 274 cm-1 is attributed to lattice defects introduced by In dopants. PMID:26517364

  10. New Insights on the Burstein-Moss Shift and Band Gap Narrowing in Indium-Doped Zinc Oxide Thin Films

    PubMed Central

    Saw, K. G.; Aznan, N. M.; Yam, F. K.; Ng, S. S.; Pung, S. Y.

    2015-01-01

    The Burstein-Moss shift and band gap narrowing of sputtered indium-doped zinc oxide (IZO) thin films are investigated as a function of carrier concentrations. The optical band gap shifts below the carrier concentration of 5.61 × 1019 cm-3 are well-described by the Burstein-Moss model. For carrier concentrations higher than 8.71 × 1019 cm-3 the shift decreases, indicating that band gap narrowing mechanisms are increasingly significant and are competing with the Burstein-Moss effect. The incorporation of In causes the resistivity to decrease three orders of magnitude. As the mean-free path of carriers is less than the crystallite size, the resistivity is probably affected by ionized impurities as well as defect scattering mechanisms, but not grain boundary scattering. The c lattice constant as well as film stress is observed to increase in stages with increasing carrier concentration. The asymmetric XPS Zn 2p3/2 peak in the film with the highest carrier concentration of 7.02 × 1020 cm-3 suggests the presence of stacking defects in the ZnO lattice. The Raman peak at 274 cm-1 is attributed to lattice defects introduced by In dopants. PMID:26517364

  11. Observation of coherently enhanced tunable narrow-band terahertz transition radiation from a relativistic sub-picosecond electron bunch train

    SciTech Connect

    Piot, P.; Sun, Y. -E; Maxwell, T. J.; Ruan, J.; Lumpkin, A. H.; Rihaoui, M. M.; Thurman-Keup, R.

    2011-06-27

    We experimentally demonstrate the production of narrow-band (?f/f ~ =20% at f ~ = 0.5 THz) THz transition radiation with tunable frequency over [0.37, 0.86] THz. The radiation is produced as a train of sub-picosecond relativistic electron bunches transits at the vacuum-aluminum interface of an aluminum converter screen. In addition, we show a possible application of modulated beams to extend the dynamical range of a popular bunch length diagnostic technique based on the spectral analysis of coherent radiation.

  12. SciNOvA: A Measurement of Neutrino-Nucleus Scattering in a Narrow-Band Beam

    SciTech Connect

    Paley, J.; Djurcic, Z.; Harris, D.; Tesarek, R.; Feldman, G.; Corwin, L.; Messier, M.D.; Mayer, N.; Musser, J.; Paley, J.; Tayloe, R.; /Indiana U. /Iowa State U. /Minnesota U. /South Carolina U. /Wichita State U. /William-Mary Coll.

    2010-10-15

    We propose to construct and deploy a fine-grained detector in the Fermilab NOvA 2 GeV narrow-band neutrino beam. In this beam, the detector can make unique contributions to the measurement of quasi-elastic scattering, neutral-current elastic scattering, neutral-current {pi}{sup 0} production, and enhance the NOvA measurements of electron neutrino appearance. To minimize cost and risks, the proposed detector is a copy of the SciBar detector originally built for the K2K long baseline experiment and used recently in the SciBooNE experiment.

  13. The infrared emission bands. III. Southern IRAS sources.

    PubMed

    Cohen, M; Tielens, A G; Bregman, J; Witteborn, F C; Rank, D M; Allamandola, L J; Wooden, D H; de Muizon, M

    1989-06-01

    We present airborne 5-8 micrometers spectra of southern IRAS sources which reveal strong polycyclic aromatic hydrocarbon (PAH) emission features. The good correlation between the bands, in particular the dominant 6.2 and "7.7" micrometers features, strongly imply a common carrier, reinforcing the PAH hypothesis. However, small but detectable spectral variations exist. Planetaries have a distinctly different ratio of I(6.2)/I(7.7) than other nebulae, accompanied by a redward shift in the actual wavelength of the "7.7" micrometers peak. Further, we have detected a new feature, previously predicted from laboratory spectra of PAH molecules, at 5.2 micrometers in many of these sources. Spectra of two rare [WC 10] planetary nebular nuclei indicate a very prominent plateau of emission, linking the 6.2 and 7.7 micrometers bands. Several of our sources show definite evidence for emission structure between 14 and 23 micrometers in their IRAS Low-Resolution Spectral Atlas spectra: we attribute this structure to PAH bands. too. We have defined the "generic" spectrum of emission bands relating the mean intensities of each band to that of the strongest, near 7.7 micrometers. We have added three more planetary or protoplanetary nebulae to our correlation between 7.7 micrometers band intensity and nebular gas phase C/O ratio, namely NGC 6302, HR 4049, and the highly carbon-rich [WC 10] nucleus, CPD--56 degrees 8032. For the latter we have determined a ratio for C/O of approximately 4.8 from IUE observations. The good correlation between the intensity ratio of the "7.7" micrometers feature relative to the far-infrared dust continuum and nebular C/O also supports a carbonaceous carrier for these emission features. PMID:11542167

  14. Forward-bias capacitance and current measurements for determining lifetimes and band narrowing in p-n junction solar cells

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.; Chen, P. J.; Pao, S. C.; Lindholm, F. A.

    1978-01-01

    A new method is described and illustrated for determining the minority-carrier diffusion length and lifetime in the base region of p-n junction solar cells. The method requires only capacitance measurements at the device terminals and its accuracy is estimated to be + or - 5%. It is applied to a set of silicon p-n junction devices and the values of the diffusion lengths agree with those obtained using the current response to X-ray excitation but disagree with those obtained by the OCVD method. The reasons for the relative inaccuracy of OCVD applied to silicon devices are discussed. The capacitance method includes corrections for a two-dimensional fringing effects which occur in small area devices. For a device having highly-doped base region and surface (emitter) layer, the method can be extended to enable the determination of material properties of the degenerately doped surface layer. These material properties include the phenomenological emitter lifetime and a measure of the energy band-gap narrowing in the emitter. An alternate method for determining the energy band-gap narrowing from temperature dependence of emitter current is discussed and demonstrated.

  15. Average Metallicity and Star Formation Rate of Lya Emitters Probed by a Triple Narrow-Band Survey

    E-print Network

    Nakajima, Kimihiko; Shimasaku, Kazuhiro; Ono, Yoshiaki; Lee, Janice C; Foucaud, Sebastien; Ly, Chun; Dale, Daniel A; Salim, Samir; Finn, Rose; Almaini, Omar; Okamura, Sadanori

    2011-01-01

    We present the average metallicity and star-formation rate of Lya emitters (LAEs) measured from our large-area survey with three narrow-band (NB) filters covering the Lya, [OII]3727, and Ha+[NII] lines of LAEs at z=2.2. We select 919 z=2.2 LAEs from Subaru/Suprime-Cam NB data in conjunction with Magellan/IMACS spectroscopy. Of these LAEs, 561 and 105 are observed with KPNO/NEWFIRM near-infrared NB filters whose central wavelengths are matched to redshifted [OII] and Ha nebular lines, respectively. By stacking the near-infrared images of the LAEs, we successfully obtain average nebular-line fluxes of LAEs, the majority of which are too faint to be identified individually by narrow-band imaging or deep spectroscopy. The stacked object has an Ha luminosity of 1.7x10^{42} erg s^{-1} corresponding to a star formation rate (SFR) of 13 M_{sun} yr^{-1}. We estimate, for the first time, the average metallicity of LAEs to be Z>~0.16 Z_{sun} based on the [OII]/(Ha+[NII]) index together with photo-ionization models and e...

  16. Five years of Project META - An all-sky narrow-band radio search for extraterrestrial signals

    NASA Technical Reports Server (NTRS)

    Horowitz, Paul; Sagan, Carl

    1993-01-01

    We have conducted a five-year search of the northern sky (delta between 30 and 60 deg) for narrow-band radio signals near the 1420 MHz line of neutral hydrogen, and its second harmonic, using an 8.4 x 10 exp 6 channel Fourier spectrometer of 0.05 Hz resolution and 400 kHz instantaneous bandwidth. The observing frequency was corrected both for motions with respect to three astronomical inertial frames, and for the effect of Earth's rotation, which provides a characteristic changing Doppler signature for narrow-band signals of extraterrestrial origin. Among the 6 x 10 exp 13 spectral channels searched, we have found 37 candidate events exceeding the average detection threshold of 1.7 x 10 exp -23 W/sq m, none of which was detected upon reobservation. The strongest of these appear to be dominated by rare processor errors. However, the strongest signals that survive culling for terrestrial interference lie in or near the Galactic plane. We describe the search and candidate events, and set limits on the prevalence of supercivilizations transmitting Doppler-precompensated beacons at H I or its second harmonic. We conclude with recommendations for future searches, based upon these findings, and a description of our next-generation search system.

  17. Characterization of Narrow Band Filters for Infrared The Brfl and H 2 filters

    E-print Network

    Testi, Leonardo

    of such a device can be described by means of a plane plate model with effective refractive index n e , thickness d recombination lines (Paschen and Brackett series), vibration­rotation transitions of molecular hydro­ gen, forbidden lines of ionized iron and vibrational bands of CO. For this reason some filters centered

  18. Narrow band deformable registration of prostate magnetic resonance imaging, magnetic resonance spectroscopic imaging, and computed tomography studies

    SciTech Connect

    Schreibmann, Eduard; Xing Lei . E-mail: lei@reyes.stanford.edu

    2005-06-01

    Purpose: Endorectal (ER) coil-based magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) is often used to obtain anatomic and metabolic images of the prostate and to accurately identify and assess the intraprostatic lesions. Recent advancements in high-field (3 Tesla or above) MR techniques affords significantly enhanced signal-to-noise ratio and makes it possible to obtain high-quality MRI data. In reality, the use of rigid or inflatable endorectal probes deforms the shape of the prostate gland, and the images so obtained are not directly usable in radiation therapy planning. The purpose of this work is to apply a narrow band deformable registration model to faithfully map the acquired information from the ER-based MRI/MRSI onto treatment planning computed tomography (CT) images. Methods and Materials: A narrow band registration, which is a hybrid method combining the advantages of pixel-based and distance-based registration techniques, was used to directly register ER-based MRI/MRSI with CT. The normalized correlation between the two input images for registration was used as the metric, and the calculation was restricted to those points contained in the narrow bands around the user-delineated structures. The narrow band method is inherently efficient because of the use of a priori information of the meaningful contour data. The registration was performed in two steps. First, the two input images were grossly aligned using a rigid registration. The detailed mapping was then modeled by free form deformations based on B-spline. The limited memory Broyden-Fletcher-Goldfarb-Shanno algorithm (L-BFGS), which is known for its superior performance in dealing with high-dimensionality problems, was implemented to optimize the metric function. The convergence behavior of the algorithm was studied by self-registering an MR image with 100 randomly initiated relative positions. To evaluate the performance of the algorithm, an MR image was intentionally distorted, and an attempt was then made to register the distorted image with the original one. The ability of the algorithm to recover the original image was assessed using a checkerboard graph. The mapping of ER-based MRI onto treatment planning CT images was carried out for two clinical cases, and the performance of the registration was evaluated. Results: A narrow band deformable image registration algorithm has been implemented for direct registration of ER-based prostate MRI/MRSI and CT studies. The convergence of the algorithm was confirmed by starting the registration experiment from more than 100 different initial conditions. It was shown that the technique can restore an MR image from intentionally introduced deformations with an accuracy of approximately 2 mm. Application of the technique to two clinical prostate MRI/CT registrations indicated that it is capable of producing clinically sensible mapping. The whole registration procedure for a complete three-dimensional study (containing 256 x 256 x 64 voxels) took less than 15 min on a standard personal computer, and the convergence was usually achieved in fewer than 100 iterations. Conclusions: A deformable image registration procedure suitable for mapping ER-based MRI data onto planning CT images was presented. Both hypothetical tests and patient studies have indicated that the registration is reliable and provides a valuable tool to integrate the ER-based MRI/MRSI information to guide prostate radiation therapy treatment.

  19. IEEE TRANSACTIONS ON AUDIO, SPEECH, AND LANGUAGE PROCESSING, VOL. 14, NO. 2, MARCH 2006 609 Perceptual Coding of Narrow-Band

    E-print Network

    Kabal, Peter

    with good perceptual quality. Audio files require a lot of bandwidth (or memory) for transmission (or good sound quality. A. Motivation for Low Rate Coding of Narrow-Band Audio Signals Although a lot of research has been done on high-quality coding of wide-band audio signals over the past decade [2]­[6], new

  20. Assessment of MODIS Thermal Emissive Band On-Orbit Calibration

    NASA Technical Reports Server (NTRS)

    Chang, Tiejun; Xiong, Xiaoxiong

    2011-01-01

    Sixteen Moderate Resolution Imaging Spectroradiometer thermal emissive bands (TEBs) cover the wavelength from 3.75 to 14.24 m. TEB calibration uses data collected from the detector responses to the onboard blackbody (BB) and space view. The BB was designed to operate either at a constant temperature for detector linear gain calibration or at temperatures varying from ambient ( 270 K) to 315 K for on-orbit characterization of nonlinear coefficients. In this paper, we assess TEB on-orbit calibration performance in two aspects: One is to review the calibration trending on the orbital, daily, and multiyear timescales, and the other is to analyze the on-orbit calibration radiance uncertainty and its impact on the calibration. The calibration trending confirms the detector response dependence on the instrument temperature. The temperature trending and prelaunch characterization provide the basis for determining the calibration radiance source temperature range and uncertainties. An analytical approach was used to assess the impacts of onboard radiance uncertainties. The BB emission uncertainty, resulting from the temperature measurement error and emissivity uncertainty, causes a calibration uncertainty up to 0.3%, a value decreasing with the band wavelength. The BB nonblackness effect is analyzed and found to be insignificant. For the band with the lowest BB emissivity, the nonblackness affects the calibration radiance by less than 0.08%. The cavity emission uncertainty and the scan-mirror emission uncertainty both cause a less than 0.1% calibration uncertainty. The analysis of the nonlinear calibration coefficient uncertainty shows that its effect on the low Earth-view brightness-temperature range varies by band and is generally insignificant.

  1. ROSAT PSPC spectra of X-ray selected narrow emission line galaxies

    NASA Technical Reports Server (NTRS)

    Colmenero, E. Romero; Carrera, F. J.; Branduardi-Raymont, G.; Mittaz, J. P. D.; McHardy, I. M.; Jones, L. R.

    1996-01-01

    The Rosat Position Sensitive Proportional Counter (PSPC) spectra of a sample of 35 X-ray selected Narrow Emission Line Galaxies (NELGs) are presented. Of these 35 objects, 16 are from the Rosat International X-ray Optical Survey (RIXOS) and the remaining 19 were discovered during the optical identification of Rosat U.K. deep survey sources. A power law model with low energy absorption set at the Galactic value is found to be a good fit for all sources. The results indicate that the spectral slope of NELGs is flatter than that of active galactic nuclei.

  2. Observation of soft X-ray spectra from a Seyfert 1 and a narrow emission-line galaxy

    NASA Technical Reports Server (NTRS)

    Singh, K. P.; Garmire, G. P.; Nousek, J.

    1985-01-01

    The 0.2-40 keV X-ray spectra of the Seyfert 1 galaxy Mrk 509 and the narrow emission-line galaxy NGC 2992 are analyzed. The results suggest the presence of a steep soft X-ray component in Mrk 509 in addition to the well-known Gamma = 1.7 component found in other active galactic nuclei in the 2-40 keV energy range. The soft X-ray component is interpreted as due to thermal emission from a hot gas, probably associated with the highly ionized gas observed to be outflowing from the galaxy. The X-ray spectrum of NGC 2992 does not show any steepening in the soft X-ray band and is consistent with a single power law (Gamma = 1.78) with very low absorbing column density of 4 x 10 to the 21st/sq cm. A model with partial covering of the nuclear X-ray source is preferred, however, to a simple model with a single power law and absorption.

  3. Spectrally Narrowed Edge Emission from Organic Light-Emitting Diodes: Evidence for Amplified Spontaneous Emission and Mirrorless Lasing

    E-print Network

    Yun Tian; Zhengqing Gan; Zhaoqun Zhou; Ji-hun Kang; Q-Han Park; David W. Lynch; Joseph Shinar

    2007-01-14

    p-Conjugated materials, including small molecules and polymers, are attracting substantial attention as novel gain media in semiconductor lasers; they offer many potential advantages not achievable with conventional inorganic semiconductors: simple processing, low cost, easy tuneability of the spectrum, and large-area integration on flexible substrates. Optically pumped lasing action in various small molecular and polymeric p-conjugated materials has been demonstrated using several resonator configurations. However, electrically pumped organic semiconductor lasers, i.e., organic injection or diode lasers, remain elusive, presumably due to various loss mechanisms, e.g., charge (polaron)-induced absorption and metal electrode absorption. Here we report on evidence for amplified spontaneous emission (ASE), also known as mirrorless lasing (i.e., wherein some of the spontaneously emitted photons are amplified by stimulated emission during their propagation) in DC-driven small molecular organic light-emitting diodes (SMOLEDs). The evidence includes a dramatic spectral line narrowing, with a full width at half maximum (FWHM) of only 5 - 10 nm, and optical gain, of the edge-emission from SMOLEDs at room temperature. However, there is no clear indication of threshold behavior associated with this spectral narrowing. Nevertheless, this discovery should pave the way towards the realization of an organic diode laser.

  4. 500 days of Stromgren b, y and narrow-band [OIII], H ? photometric evolution of gamma-ray Nova Del 2013 (=V339 Del)

    NASA Astrophysics Data System (ADS)

    Munari, Ulisse; Maitan, Alessandro; Moretti, Stefano; Tomaselli, Salvatore

    2015-10-01

    We present and discuss highly accurate photometry obtained through medium Stromgren y, b bands and narrow [OIII], H? bands covering 500 days of the evolution of Nova Del 2013 since its maximum brightness. This is by far the most complete study of any nova observed in such photometric systems. The nova behavior in these photometric bands is very different from that observed with the more conventional broad bands like UBVRC IC or u?g?r?i?z? , providing unique information about extent and ionization of the ejecta, the onset of critical phases like the transition between optically thick and thin conditions, and re-ionization by the central super-soft X-ray source. The actual transmission profiles of the y, b , [OIII] and H? photometric filters have been accurately measured at different epochs and different illumination angles, to evaluate in detail their performance under exact operating conditions. The extreme smoothness of both the H? and [OIII] lightcurves argues for absence of large and abrupt discontinuities in the ejecta of Nova Del 2013. Should they exist, glitches in the lightcurves would have appeared when the ionization and/or recombination fronts overtook them. During the period of recorded very large variability (up to 100× over a single day) in the super-soft X-ray emission (from day +69 to +86 past V maximum), no glitch in excess of 1% was observed in the optical photometry, either in the continuum (Stromgren y) or in the lines ([OIII] and H? filters), or in a combination of the two (Stromgren b, Johnson B and V). Considering that the recombination time scale in the ejecta was one week at that time, this excludes global changes of the white dwarf as the source of the X-ray variability and supports instead clumpy ejecta passing through the line of sight to us as its origin.

  5. Prediction of corridor effect from the launching of the satellite power system. [air pollutant concentration into narrow band of latitude

    NASA Technical Reports Server (NTRS)

    Borucki, W. J.; Whitten, R. C.; Woodward, H. T.; Capone, L. A.; Riegel, C. A.

    1982-01-01

    A diagnostic model is developed to define the parameters which control the corridor effect of contaminants deposited in a narrow latitudinal band of the earth's atmosphere by numerous launches of the STS and heavy lift launch vehicles for construction of satellite solar power systems. Identified factors included the pollution injection rate, the ambient background levels of the pollutant species, and the transport properties related to the dilution rate of the chemicals. If the chemical life of the pollutant was shorter or the same length of time as the transport time, alterations in the chemical production and loss rates were found to be parameters necessarily added to the model. A comparison with NASA Ames Research Center two-dimensional model results indicate that the corridor effect was possile with operations above 60 km in the case of H2O, H2, and NO production.

  6. The impact of mismatch on the performance of coded narrow-band FM with limiter/discriminator detection

    NASA Technical Reports Server (NTRS)

    Simon, M. K.

    1983-01-01

    An examination of the impact of mismatch on the performance of convolutionally encoded/Viterbi decoded narrow-band FM with limiter/discriminator detection is presented. Attention was given to the potential gain available by the combination of this type of system in terms of hard and soft decision decoding. Soft decision decoding was demonstrated to offer only approximately 0.3 dB better performance than hard decision coding. It was also shown, through a technique involving the number of clicks occurring in each detection interval, that both soft and hard decision decoding bit error probability performance could be improved. It is concluded that the mismatch between the coding channel and the decoding metric of the Viterbi algorithm is responsible for reducing the difference between hard and soft decoding metrics.

  7. Narrow Band Source of Transform-Limited Photon Pairs via Four-Wave Mixing in a Cold Atomic Ensemble

    NASA Astrophysics Data System (ADS)

    Srivathsan, Bharath; Gulati, Gurpreet Kaur; Chng, Brenda; Maslennikov, Gleb; Matsukevich, Dzmitry; Kurtsiefer, Christian

    2013-09-01

    We observe narrow band pairs of time-correlated photons of wavelengths 776 and 795 nm from nondegenerate four-wave mixing in a laser-cooled atomic ensemble of Rb87 using a cascade decay scheme. Coupling the photon pairs into single mode fibers, we observe an instantaneous rate of 7700 pairs per second with silicon avalanche photodetectors, and an optical bandwidth below 30 MHz. Detection events exhibit a strong correlation in time [g(2)(?=0)?5800] and a high coupling efficiency indicated by a pair-to-single ratio of 23%. The violation of the Cauchy-Schwarz inequality by a factor of 8.4×106 indicates a strong nonclassical correlation between the generated fields, while a Hanbury Brown-Twiss experiment in the individual photons reveals their thermal nature. The comparison between the measured frequency bandwidth and 1/e decay time of g(2) indicates a transform-limited spectrum of the photon pairs. The narrow bandwidth and brightness of our source makes it ideal for interacting with atomic ensembles in quantum communication protocols.

  8. Design of narrow band XUV and EUV coronagraphs using multilayer optics

    NASA Technical Reports Server (NTRS)

    Walker, A. B. C., Jr.; Allen, Maxwell J.; Barbee, Troy W., Jr.; Hoover, Richard B.

    1991-01-01

    A novel approach to the study of the solar corona is described, which enables observation of the soft X-ray (XUV), EUV, and FUV emission of the highly ionized ions present in the corona. The principal advantage of this approach is a relatively low contrast between the innner corona and the solar disk at the wavelengths involved; the contrast between coronal visible light and the XUV or EUV light is about 1. The design and the anticipated performances of the XUV and EUV coronagraphs using normal incidence multilayer optics are described.

  9. Tunable narrow band difference frequency THz wave generation in DAST via dual seed PPLN OPG.

    PubMed

    Dolasinski, Brian; Powers, Peter E; Haus, Joseph W; Cooney, Adam

    2015-02-01

    We report a widely tunable narrowband terahertz (THz) source via difference frequency generation (DFG). A narrowband THz source uses the output of dual seeded periodically poled lithium niobate (PPLN) optical parametric generators (OPG) combined in the nonlinear crystal 4-dimthylamino-N-methyl-4-stilbazolium-tosylate (DAST). We demonstrate a seamlessly tunable THZ output that tunes from 1.5 THz to 27 THz with a minimum bandwidth of 3.1 GHz. The effects of dispersive phase matching, two-photon absorption, and polarization were examined and compared to a power emission model that consisted of the current accepted parameters of DAST. PMID:25836219

  10. Mapping the large-scale structure around a z = 1.46 galaxy cluster in 3D using two adjacent narrow-band filters

    NASA Astrophysics Data System (ADS)

    Hayashi, Masao; Kodama, Tadayuki; Koyama, Yusei; Tadaki, Ken-ichi; Tanaka, Ichi; Shimakawa, Rhythm; Matsuda, Yuichi; Sobral, David; Best, Philip N.; Smail, Ian

    2014-04-01

    We present a novel method to estimate accurate redshifts of star-forming galaxies by measuring the flux ratio of the same emission line observed through two adjacent narrow-band filters. We apply this method to our NB912 and new NB921 data taken with Suprime-Cam on the Subaru Telescope of a galaxy cluster, XMMXCS J2215.9-1738, at z = 1.46 and its surrounding structures. We obtain redshifts for 170 [O II] emission line galaxies at z ˜ 1.46, among which 41 galaxies are spectroscopically confirmed with Multi-Object Infrared Camera and Spectrograph and Fibre Multi Object Spectrograph on the Subaru mainly, showing an accuracy of ?((z - zspec)/(1 + zspec)) = 0.002. This allows us to reveal filamentary structures that penetrate towards the centre of the galaxy cluster and intersect with other structures, consistent with the picture of hierarchical cluster formation. We also find that the projected celestial distribution does not precisely trace the real distribution of galaxies, indicating the importance of the three-dimensional view of structures to properly identify and quantify galaxy environments. We investigate the environmental dependence of galaxy properties with local density, confirming that the median colour of galaxies becomes redder in higher density region, while the star formation rate of star-forming galaxies does not depend strongly on local environment in this structure. This implies that the star-forming activity in galaxies is truncated on a relatively short time-scale in the cluster centre.

  11. Infrared FeII Emission in Narrow-Line Seyfert 1 Galaxies

    E-print Network

    A. Rodriguez-Ardila; S. M. Viegas; M. G. Pastoriza; L. Prato

    2001-09-27

    We obtained 0.8-2.4 micron spectra at a resolution of 320 km/s of four narrow-line Seyfert 1 galaxies in order to study the near-infrared properties of these objects. We focus on the analysis of the FeII emission in that region and the kinematics of the low-ionization broad lines. We found that the 1 micron FeII lines (9997 A, 10501 A, 10863 A and 11126 A) are the strongest FeII lines in the observed interval. For the first time, primary cascade lines of FeII arising from the decay of upper levels pumped by Ly-alpha fluorescence are resolved and identified in active galactic nuclei. Excitation mechanisms leading to the emission of the 1 micron FeII features are discussed. A combination of Ly-alpha fluorescence and collisional excitation are found to be the main contributors. The flux ratio between near-IR FeII lines varies from object to object, in contrast to what is observed in the optical region. A good correlation between the 1 micron and optical FeII emission is found. This suggests that the upper z4Fo and z4Do levels from which the bulk of the optical lines descend are mainly populated by the transitions leading to the 1 micron lines. The width and profile shape of FeII 11127, CaII 8642 and OI 8446 are very similar but significantly narrower than Pa-beta, giving strong observational support to the hypothesis that the region where FeII, CaII and OI are produced are co-spatial, interrelated kinematically and most probably located in the outermost portion of the BLR.

  12. Spectrally narrowed leaky waveguide edge emission and transient electrluminescent dynamics of OLEDs

    SciTech Connect

    Zhengqing, Gan

    2010-05-16

    In summary, there are two major research works presented in this dissertation. The first research project (Chapter 4) is spectrally narrowed edge emission from Organic Light Emitting Diodes. The second project (Chapter 5) is about transient electroluminescent dynamics in OLEDs. Chapter 1 is a general introduction of OLEDs. Chapter 2 is a general introduction of organic semiconductor lasers. Chapter 3 is a description of the thermal evaporation method for OLED fabrication. The detail of the first project was presented in Chapter 4. Extremely narrowed spectrum was observed from the edge of OLED devices. A threshold thickness exists, above which the spectrum is narrow, and below which the spectrum is broad. The FWHM of spectrum depends on the material of the organic thin films, the thickness of the organic layers, and length of the OLED device. A superlinear relationship between the output intensity of the edge emission and the length of the device was observed, which is probably due to the misalignment of the device edge and the optical fiber detector. The original motivation of this research is for organic semiconductor laser that hasn't been realized due to the extremely high photon absorption in OLED devices. Although we didn't succeed in fabricating an electrically pumped organic laser diode, we made a comprehensive research in edge emission of OLEDs which provides valuable results in understanding light distribution and propagation in OLED devices. Chapter 5 focuses on the second project. A strong spike was observed at the falling edge of a pulse, and a long tail followed. The spike was due to the recombination of correlated charge pair (CCP) created by trapped carriers in guest molecules of the recombination zone. When the bias was turned off, along with the decreasing of electric field in the device, the electric field induced quenching decreases and the recombination rate of the CCP increases which result in the spike. This research project provides a profound understanding of the EL dynamics of OLED, and the theoretical model can fit and explain the experiment data quite well. For the edge emission, we focused on the spectrum and the relative intensity of the edge emission. In the future, more research can be done on the comparison of the intensity between the total edge emission and the surface emission which will give us a sense what fraction of light was trapped in the device. Micro structures can be integrated into the OLED such as DFB and DBR, the character of edge emission should be very interesting. For the transient spike, the CCP model can give a good explanation. But in the model, the effect of the electric field change is not included, because from the start point (t=0), we assume the mobility of carriers is a constant. If we consider the details of the change of the electric field, then when turning of the bias, the decrease of the electric field results in decrease of the carrier mobility and the dissociation rate. If we can add the electric field effect into the model, the whole theory will be more convincing.

  13. Narrow-Band Images of Star Forming Knots in HII Galaxies

    NASA Astrophysics Data System (ADS)

    Lagos, P.; Telles, E.; Melnick, J.

    2006-06-01

    HII galaxies are low-luminosity, metal poor and compact objects with intense star formation activity. Initially it was hypothesized that HII galaxies are young galaxies, forming their first generation of stars. However, Optical-NIR photometry have revealed the existence of an evolved underlying population of old stars, suggesting an intermittent star formation history with short intense star-forming episodes followed by long quiescent phases. HII galaxies in general are simple systems compared to other galaxies, more massive galaxies, and many of them have more than one starburst component, turning these objects in excellent laboratories to study the star-formation mechanism, supernova winds and chemical evolution. Due to their intense emission lines, HII galaxies have been common targets of spectroscopic works. These have biased the results to the location of the brightest regions where slits have been positioned. Using narrowband H? and true continuum images obtained with the NTT telescope on La Silla, we have studied a selected HII galaxies, producing continuum free H? emission lines images. The images revealed a myriad of blobby structures due to the presence of multiple star forming knots, filaments or possible expanding shells, probably superbubbles. >From these we could map the distribution of luminosity and EW over the whole extension of the galaxies. Our integrated H? flux, over similar apertures, is in good agreement with the slit spectroscopy. However, the EW (H?) distribution is non-uniform and varies significantly over the different star forming knots. Thus, integrated values appear only as an average of the star forming regions, hampering the fine determination of individual star cluster ages.

  14. Precise photometric redshifts with a narrow-band filter set: The PAU Survey at the William Herschel Telescope

    E-print Network

    Martí, Pol; Castander, Francisco J; Gaztañaga, Enrique; Eriksen, Martin; Sánchez, Carles

    2014-01-01

    The Physics of the Accelerating Universe (PAU) survey at the William Herschel Telescope (WHT) will use a new optical camera (PAUCam) with a large set of narrow-band filters to perform a photometric galaxy survey with a quasi-spectroscopic redshift precision of \\sigma(z)/(1 + z) ~ 0.0035 and map the large-scale structure of the universe in three dimensions up to i_AB < 22.5-23.0. In this paper we present a detailed photo-z performance study using photometric simulations for 40 equally-spaced 12.5-nm-wide (FWHM) filters with a ~25% overlap and spanning the wavelength range from 450 nm to 850 nm, together with a ugrizY broad-band filter system. We then present the migration matrix r_ij, containing the probability that a galaxy in a true redshift bin j is measured in a photo-z bin i, and study its effect on the determination of galaxy auto- and cross-correlations. Finally, we also study the impact on the photo-z performance of small variations of the filter set in terms of width, wavelength coverage, etc., and...

  15. Precise photometric redshifts with a narrow-band filter set: the PAU survey at the William Herschel Telescope

    NASA Astrophysics Data System (ADS)

    Martí, P.; Miquel, R.; Castander, F. J.; Gaztañaga, E.; Eriksen, M.; Sánchez, C.

    2014-07-01

    The Physics of the Accelerating Universe (PAU) survey at the William Herschel Telescope will use a new optical camera (PAUCam) with a large set of narrow-band filters to perform a photometric galaxy survey with a quasi-spectroscopic redshift precision of ?(z)/(1 + z) ˜ 0.0035 and map the large-scale structure of the universe in three dimensions up to iAB < 22.5-23.0. In this paper, we present a detailed photo-z performance study using photometric simulations for 40 equally spaced 12.5-nm-wide (full width at half-maximum) filters with an ˜25 per cent overlap and spanning the wavelength range from 450 to 850 nm, together with a ugrizY broad-band filter system. We then present the migration matrix rij, containing the probability that a galaxy in a true redshift bin j is measured in a photo-z bin i, and study its effect on the determination of galaxy auto- and cross-correlations. Finally, we also study the impact on the photo-z performance of small variations of the filter set in terms of width, wavelength coverage, etc., and find a broad region where slightly modified filter sets provide similar results, with the original set being close to optimal.

  16. Echolocation in sympatric Peale's dolphins (Lagenorhynchus australis) and Commerson's dolphins (Cephalorhynchus commersonii) producing narrow-band high-frequency clicks.

    PubMed

    Kyhn, L A; Jensen, F H; Beedholm, K; Tougaard, J; Hansen, M; Madsen, P T

    2010-06-01

    An increasing number of smaller odontocetes have recently been shown to produce stereotyped narrow-band high-frequency (NBHF) echolocation clicks. Click source parameters of NBHF clicks are very similar, and it is unclear whether the sonars of individual NBHF species are adapted to specific habitats or the presence of other NBHF species. Here, we test whether sympatric NBHF species sharing the same habitat show similar adaptations in their echolocation clicks and whether their clicks display signs of character displacement. Wide-band sound recordings were obtained with a six-element hydrophone array from wild Peale's (Lagenorhynchus australis) and Commerson's (Cephalorhynchus commersonii) dolphins off the Falkland Islands. The centroid frequency was different between Commerson's (133+/-2 kHz) and Peale's (129+/-3 kHz) dolphins. The r.m.s. bandwidth was 12+/-3 kHz for both species. The source level was higher for Peale's dolphin (185+/-6 dB re 1 muPa p.-p.) than for Commerson's (177+/-5 dB re 1 muPa p.-p.). The mean directivity indexes were 25 dB for both species. The relatively low source levels in combination with the high directivity index may be an adaptation to reduce clutter when foraging in a coastal environment. We conclude that the small species-specific shifts in distribution of centroid frequencies around 130 kHz may reflect character displacement in otherwise-stereotyped NBHF clicks. PMID:20472781

  17. A Morphological Study of Compact Narrow Emission Line Galaxies In The COSMOS Field

    NASA Astrophysics Data System (ADS)

    Baldassare, Vivienne; Feldman, D.; Greenbaum, A.; Hasan, I.; Mahalchick, S.; Liu, C.; COSMOS Team

    2010-01-01

    We present a morphological study of 139 spectroscopically selected compact narrow emission line galaxies (CNELGs) from the COSMOS HST Treasury Survey, using a comparison sample of field galaxies of similar magnitude obtained from the COSMOS field. The CNELGs range in magnitude from 18.13 < V < 21.95 and in redshift from 0 < z < 0.9. Preliminary results indicate that, whereas statistically the CNELGs are clearly morphologically distinct from our comparison sample, at HST resolution they are also clearly not all - or even predominantly - "compact." This work was supported by an NSF REU Site grant to The City University of New York and American Museum of Natural History; an NSF STEAM grant to the College of Staten Island; the NASA New York Space Grant program; Barnard College; and the CUNY Macaulay Honors College.

  18. A search for methane in the atmosphere of GJ 1214b via GTC narrow-band transmission spectrophotometry

    NASA Astrophysics Data System (ADS)

    Wilson, P. A.; Colón, K. D.; Sing, D. K.; Ballester, G. E.; Désert, J.-M.; Ehrenreich, D.; Ford, E. B.; Fortney, J. J.; Lecavelier des Etangs, A.; López-Morales, M.; Morley, C. V.; Pettitt, A. R.; Pont, F.; Vidal-Madjar, A.

    2014-03-01

    We present narrow-band photometric measurements of the exoplanet GJ 1214b using the 10.4 m Gran Telescopio Canarias and the Optical System for Imaging and low Resolution Integrated Spectroscopy instrument. Using tuneable filters, we observed a total of five transits, three of which were observed at two wavelengths nearly simultaneously, producing a total of eight individual light curves, six of these probed the possible existence of a methane absorption feature in the 8770-8850 Å region at high resolution. We detect no increase in the planet-to-star radius ratio across the methane feature with a change in radius ratio of ? overline{R} = -0.0007 ± 0.0017 corresponding to a scaleheight (H) change of -0.5 ± 1.2H across the methane feature, assuming a hydrogen-dominated atmosphere. We find that a variety of water and cloudy atmospheric models fit the data well, but find that cloud-free models provide poor fits. These observations support a flat transmission spectrum resulting from the presence of a high-altitude haze or a water-rich atmosphere, in agreement with previous studies. In this study, the observations are pre-dominantly limited by the photometric quality and the limited number of data points (resulting from a long observing cadence), which make the determination of the systematic noise challenging. With tuneable filters capable of high-resolution measurements (R ? 600-750) of narrow absorption features, the interpretation of our results are also limited by the absence of high-resolution methane models below 1 ?m.

  19. Full-sky survey searching for ultra-narrow-band artificial CW signals: analysis of the results of Project META

    NASA Astrophysics Data System (ADS)

    Lemarchand, Guillermo A.

    1996-06-01

    Project META (Megachannel ExtraTerrestrial Assay), a full-sky survey for artificial narrow-band signals, has been conducted from the Harvard/Smithsonian 26 m radiotelescope at Agassiz Station and from one of the two 30 m radiotelescopes of the Instituto Argentino de Radioastronomia (IAR). The search was performed near the 1420 MHz line of neutral hydrogen, and its second harmonic, using two 8.4 X 10(superscript 6) channel Fourier spectrometers of 0.05 Hz resolution and 400 kHz of instantaneous bandwidth. The observing frequency was corrected both for motions with respect to three astronomical inertial frames, and for the effect of Earth's rotation, which provides a characteristic changing signature for narrow-band signals of extraterrestrial origin. Among the 6 X 10(superscript 13) spectral channels searched in the northern hemisphere, Horowitz and Sagan reported 37 candidates events exceeding the average threshold of 1.7 X 10(superscript -23) W m(superscript -2), while in the southern hemisphere among 2 X 10(superscript 13) spectral channels analyzed we found 19 events exceeding the same threshold. The strongest signals that survive culling for terrestrial interference lie in or near the Galactic Plane. The first high resolution southern target search around 71 stars (-90 degrees narrow-band non-repeating 'events' found by Project META can be generated by (a) radiometer noise fluctuations, (b) a population of constant galactic sources which undergo deep fading and amplification due to interstellar scintillation, consistent with ETI transmissions and (c) real, transient signals of either terrestrial or extraterrestrial origin. The Bayesian test shows that hypothesis (b) and (c) are both highly preferred to (a), but the first two are about equally likely. Using this analysis we discuss the best observing strategies to determine the real origin of these 'events'.

  20. Spectral evolution and extreme value analysis of non-linear numerical simulations of narrow band random surface gravity waves.

    NASA Astrophysics Data System (ADS)

    Socquet-Juglard, H.; Dysthe, K. B.; Trulsen, K.; Liu, J.; Krogstad, H. E.

    2003-04-01

    Numerical simulations of a narrow band gaussian spectrum of random surface gravity waves have been carried out in two and three spatial dimensions [7]. Different types of non-linear Schr&{uml;o}dinger equations, [1] and [4], have been used in these simulations. Simulations have now been carried with a JONSWAP spectrum associated with a spreading function of the type cosine-squared [5]. The evolution of the spectrum, skewness, kurtosis, ... will be presented. In addition, some results about stochastic properties of the surface will be shown. Based on the approach found in [2], [3] and [6], the results are presented in terms of deviations from linear Gaussian theory and the standard second order small slope perturbation theory. begin{thebibliography}{9} bibitem{kk96} Trulsen, K. &Dysthe, K. B. (1996). A modified nonlinear Schr&{uml;o}dinger equation for broader bandwidth gravity waves on deep water. Wave Motion, 24, pp. 281-289. bibitem{BK2000} Krogstad, H.E. and S.F. Barstow (2000). A uniform approach to extreme value analysis of ocean waves, Proc. ISOPE'2000, Seattle, USA, 3, pp. 103-108. bibitem{PRK} Prevosto, M., H. E. Krogstad and A. Robin (2000). Probability distributions for maximum wave and crest heights, Coast. Eng., 40, 329-360. bibitem{ketal} Trulsen, K., Kliakhandler, I., Dysthe, K. B. &Velarde, M. G. (2000) On weakly nonlinear modulation of waves on deep water, Phys. Fluids, 12, pp. L25-L28. bibitem{onorato} Onorato, M., Osborne, A.R. and Serio, M. (2002) Extreme wave events in directional, random oceanic sea states, Phys. Fluids, 14, pp. 2432-2437. bibitem{BK2002} Krogstad, H.E. and S.F. Barstow (2002). Analysis and Applications of Second Order Models for the Maximum Crest height, % Proc. 21nd Int. Conf. Offshore Mechanics and Arctic Engineering, Oslo. Paper no. OMAE2002-28479. bibitem{JFMP} Dysthe, K. B., Trulsen, K., Krogstad, H. E. and Socquet-Juglard, H. (2002, in press) Evolution of a narrow band spectrum of random surface gravity waves, J. Fluid Mech.

  1. Application of soft-decision trellis decoding of block codes in narrow-banded image transmission system over Rayleigh fading channels

    NASA Astrophysics Data System (ADS)

    Yuan, Dong-Feng; Gao, Chun-Yan; Zhang, Li-Jun

    2000-05-01

    A new trellis decoding method of block codes based on the GAC structure is applied to Rayleigh fading channels in this paper. Performance of this decoding technique with hard- decision and soft-decision is studied respectively. Researches are also carried out to introduce this maximum- likelihood decoding method to narrow-banded mobile image transmission systems.

  2. Data analysis of gravitational-wave signals from spinning neutron stars. V. A narrow-band all-sky search

    SciTech Connect

    Astone, Pia; Borkowski, Kazimierz M.; Jaranowski, Piotr; Pietka, Maciej; Krolak, Andrzej

    2010-07-15

    We present theory and algorithms to perform an all-sky coherent search for periodic signals of gravitational waves in narrow-band data of a detector. Our search is based on a statistic, commonly called the F-statistic, derived from the maximum-likelihood principle in Paper I of this series. We briefly review the response of a ground-based detector to the gravitational-wave signal from a rotating neuron star and the derivation of the F-statistic. We present several algorithms to calculate efficiently this statistic. In particular our algorithms are such that one can take advantage of the speed of fast Fourier transform in calculation of the F-statistic. We construct a grid in the parameter space such that the nodes of the grid coincide with the Fourier frequencies. We present interpolation methods that approximately convert the two integrals in the F-statistic into Fourier transforms so that the fast Fourier transform algorithm can be applied in their evaluation. We have implemented our methods and algorithms into computer codes and we present results of the Monte Carlo simulations performed to test these codes.

  3. New high Tc multiferroics KBiFe2O5 with narrow band gap and promising photovoltaic effect

    PubMed Central

    Zhang, Ganghua; Wu, Hui; Li, Guobao; Huang, Qingzhen; Yang, Chongyin; Huang, Fuqiang; Liao, Fuhui; Lin, Jianhua

    2013-01-01

    Intrinsic polarization of ferroelectrics (FE) helps separate photon-generated charge carriers thus enhances photovoltaic effects. However, traditional FE with transition-metal cations (M) of d0 electron in MO6 network typically has a band gap (Eg) exceeding 3.0?eV. Although a smaller Eg (2.6?eV) can be obtained in multiferroic BiFeO3, the value is still too high for optimal solar energy applications. Computational “materials genome” searches have predicted several exotic MO6 FE with Eg < 2.0?eV, all thus far unconfirmed because of synthesis difficulties. Here we report a new FE compound with MO4 tetrahedral network, KBiFe2O5, which features narrow Eg (1.6?eV), high Curie temperature (Tc ~ 780?K) and robust magnetic and photoelectric activities. The high photovoltage (8.8?V) and photocurrent density (15??A/cm2) were obtained, which is comparable to the reported BiFeO3. This finding may open a new avenue to discovering and designing optimal FE compounds for solar energy applications. PMID:23405279

  4. Narrow Band Ultraviolet B Treatment for Human Vitiligo Is Associated with Proliferation, Migration, and Differentiation of Melanocyte Precursors.

    PubMed

    Goldstein, Nathaniel B; Koster, Maranke I; Hoaglin, Laura G; Spoelstra, Nicole S; Kechris, Katerina J; Robinson, Steven E; Robinson, William A; Roop, Dennis R; Norris, David A; Birlea, Stanca A

    2015-08-01

    In vitiligo, the autoimmune destruction of epidermal melanocytes produces white spots that can be repigmented by melanocyte precursors from the hair follicles, following stimulation with UV light. We examined by immunofluorescence the distribution of melanocyte markers (C-KIT, DCT, PAX3, and TYR) coupled with markers of proliferation (KI-67) and migration (MCAM) in precursors and mature melanocytes from the hair follicle and the epidermis of untreated and narrow band UVB (NBUVB)-treated human vitiligo skin. NBUVB was associated with a significant increase in the number of melanocytes in the infundibulum and with restoration of the normal melanocyte population in the epidermis, which was lacking in the untreated vitiligo. We identified several precursor populations (melanocyte stem cells, melanoblasts, and other immature phenotypes), and progressively differentiating melanocytes, some with putative migratory and/or proliferative abilities. The primary melanocyte germ was present in the untreated and treated hair follicle bulge, whereas a possible secondary melanocyte germ composed of C-KIT+ melanocytes was found in the infundibulum and interfollicular epidermis of UV-treated vitiligo. This is an exceptional model for studying the mobilization of melanocyte stem cells in human skin. Improved understanding of this process is essential for designing better treatments for vitiligo, ultimately based on melanocyte stem cell activation and mobilization. PMID:25822579

  5. Toward Photochemical Water Splitting Using Band-Gap-Narrowed Semiconductors and Transition-Metal Based Molecular Catalysts

    SciTech Connect

    Muckerman,J.T.; Rodriguez, J.A.; Fujita, E.

    2009-06-07

    We are carrying out coordinated theoretical and experimental studies of toward photochemical water splitting using band-gap-narrowed semiconductors (BGNSCs) with attached multi-electron molecular water oxidation and hydrogen production catalysts. We focus on the coupling between the materials properties and the H{sub 2}O redox chemistry, with an emphasis on attaining a fundamental understanding of the individual elementary steps in the following four processes: (1) Light-harvesting and charge-separation of stable oxide or oxide-derived semiconductors for solar-driven water splitting, including the discovery and characterization of the behavior of such materials at the aqueous interface; (2) The catalysis of the four-electron water oxidation by dinuclear hydroxo transition-metal complexes with quinonoid ligands, and the rational search for improved catalysts; (3) Transfer of the design principles learned from the elucidation of the DuBois-type hydrogenase model catalysts in acetonitrile to the rational design of two-electron hydrogen production catalysts for aqueous solution; (4) Combining these three elements to examine the function of oxidation catalysts on BGNSC photoanode surfaces and hydrogen production catalysts on cathode surfaces at the aqueous interface to understand the challenges to the efficient coupling of the materials functions.

  6. New high T(c) multiferroics KBiFe?O? with narrow band gap and promising photovoltaic effect.

    PubMed

    Zhang, Ganghua; Wu, Hui; Li, Guobao; Huang, Qingzhen; Yang, Chongyin; Huang, Fuqiang; Liao, Fuhui; Lin, Jianhua

    2013-01-01

    Intrinsic polarization of ferroelectrics (FE) helps separate photon-generated charge carriers thus enhances photovoltaic effects. However, traditional FE with transition-metal cations (M) of d? electron in MO? network typically has a band gap (E(g)) exceeding 3.0?eV. Although a smaller E(g) (2.6?eV) can be obtained in multiferroic BiFeO?, the value is still too high for optimal solar energy applications. Computational "materials genome" searches have predicted several exotic MO? FE with E(g) < 2.0?eV, all thus far unconfirmed because of synthesis difficulties. Here we report a new FE compound with MO? tetrahedral network, KBiFe?O?, which features narrow E(g) (1.6?eV), high Curie temperature (T(c) ~ 780?K) and robust magnetic and photoelectric activities. The high photovoltage (8.8?V) and photocurrent density (15??A/cm²) were obtained, which is comparable to the reported BiFeO?. This finding may open a new avenue to discovering and designing optimal FE compounds for solar energy applications. PMID:23405279

  7. Correlation between Reversal of DNA Methylation and Clinical Symptoms in Psoriatic Epidermis Following Narrow-Band UVB Phototherapy.

    PubMed

    Gu, Xiaolian; Nylander, Elisabet; Coates, Philip J; Fahraeus, Robin; Nylander, Karin

    2015-08-01

    Epigenetic modifications by DNA methylation are associated with a wide range of diseases. Previous studies in psoriasis have concentrated on epigenetic changes in immune cells or in total skin biopsies that include stromal-associated changes. In order to improve our understanding of the role of DNA methylation in psoriasis, we sought to obtain a comprehensive DNA methylation signature specific for the epidermal component of psoriasis and to analyze methylation changes during therapy. Genome-wide DNA methylation profiling of epidermal cells from 12 patients undergoing narrow-band UVB phototherapy and 12 corresponding healthy controls revealed a distinct DNA methylation pattern in psoriasis compared with controls. A total of 3,665 methylation variable positions (MVPs) were identified with an overall hypomethylation in psoriasis patient samples. DNA methylation pattern was reversed at the end of phototherapy in patients showing excellent clinical improvement. Only 7% of phototherapy-affected MVPs (150 out of 2,108) correlate with nearby gene expression. Enrichment of MVPs in enhancers indicates tissue-specific modulation of the transcriptional regulatory machinery in psoriasis. Our study identified key epigenetic events associated with psoriasis pathogenesis and helps understand the dynamic DNA methylation landscape in the human genome. PMID:25830654

  8. Banks of templates for all-sky narrow-band searches of gravitational waves from spinning neutron stars

    E-print Network

    Andrzej Pisarski; Piotr Jaranowski

    2015-08-07

    We construct efficient banks of templates suitable for all-sky narrow-band searches of almost monochromatic gravitational waves originating from spinning neutron stars in our Galaxy in data collected by interferometric detectors. We consider waves with one spindown parameter included and we assume that both the position of the gravitational-wave source in the sky and the wave's frequency together with spindown parameter are unknown. In the construction we employ simplified model of the signal with constant amplitude and phase which is a linear function of unknown parameters. Our template banks enable usage of the fast Fourier transform algorithm in the computation of the maximum-likelihood $\\mathcal{F}$-statistic for nodes of the grids defining the bank and fulfill an additional constraint needed to resample the data to barycentric time efficiently. All these template bank features were employed in the recent all-sky $\\mathcal{F}$-statistic-based search for continuous gravitational waves in Virgo VSR1 data [J.Aasi et al., Classical Quantum Gravity 31, 165014 (2014)]. Here we improve that template bank by constructing templates suitable for larger range of search parameters and of smaller thicknesses for certain values of search parameters. One of our template banks has thickness 12% smaller than the thickness of the template bank used in the all-sky search of Virgo VSR1 data and only 4% larger than the thickness of 4-dimensional optimal lattice covering $A_4^\\star$.

  9. Correlation between Reversal of DNA Methylation and Clinical Symptoms in Psoriatic Epidermis Following Narrow-Band UVB Phototherapy

    PubMed Central

    Gu, Xiaolian; Nylander, Elisabet; Coates, Philip J; Fahraeus, Robin; Nylander, Karin

    2015-01-01

    Epigenetic modifications by DNA methylation are associated with a wide range of diseases. Previous studies in psoriasis have concentrated on epigenetic changes in immune cells or in total skin biopsies that include stromal-associated changes. In order to improve our understanding of the role of DNA methylation in psoriasis, we sought to obtain a comprehensive DNA methylation signature specific for the epidermal component of psoriasis and to analyze methylation changes during therapy. Genome-wide DNA methylation profiling of epidermal cells from 12 patients undergoing narrow-band UVB phototherapy and 12 corresponding healthy controls revealed a distinct DNA methylation pattern in psoriasis compared with controls. A total of 3,665 methylation variable positions (MVPs) were identified with an overall hypomethylation in psoriasis patient samples. DNA methylation pattern was reversed at the end of phototherapy in patients showing excellent clinical improvement. Only 7% of phototherapy-affected MVPs (150 out of 2,108) correlate with nearby gene expression. Enrichment of MVPs in enhancers indicates tissue-specific modulation of the transcriptional regulatory machinery in psoriasis. Our study identified key epigenetic events associated with psoriasis pathogenesis and helps understand the dynamic DNA methylation landscape in the human genome. PMID:25830654

  10. Empirical determination of the energy band gap narrowing in p{sup +} silicon heavily doped with boron

    SciTech Connect

    Yan, Di Cuevas, Andres

    2014-11-21

    In the analysis of highly doped silicon, energy band gap narrowing (BGN) and degeneracy effects may be accounted for separately, as a net BGN in conjunction with Fermi-Dirac statistics, or lumped together in an apparent BGN used with Boltzmann statistics. This paper presents an experimental study of silicon highly doped with boron, with the aim of evaluating the applicability of previously reported BGN models. Different boron diffusions covering a broad range of dopant densities were prepared, and their characteristic recombination current parameters J{sub 0} were measured using a contactless photoconductance technique. The BGN was subsequently extracted by matching theoretical simulations of carrier transport and recombination in each of the boron diffused regions and the measured J{sub 0} values. An evaluation of two different minority carrier mobility models indicates that their impact on the extraction of the BGN is relatively small. After considering possible uncertainties, it can be concluded that the BGN is slightly larger in p{sup +} silicon than in n{sup +} silicon, in qualitative agreement with theoretical predictions by Schenk. Nevertheless, in quantitative terms that theoretical model is found to slightly underestimate the BGN in p{sup +} silicon. With the two different parameterizations derived in this paper for the BGN in p{sup +} silicon, both statistical approaches, Boltzmann and Fermi-Dirac, provide a good agreement with the experimental data.

  11. A Search for Methane in the Atmosphere of GJ 1214b via GTC Narrow-Band Transmission Spectrophotometry

    E-print Network

    Wilson, P A; Sing, D K; Ballester, G E; Désert, J -M; Ehrenreich, D; Ford, E B; Fortney, J J; Etangs, A Lecavelier des; López-Morales, M; Morley, C V; Pettitt, A R; Pont, F; Vidal-Madjar, A

    2013-01-01

    We present narrow-band photometric measurements of the exoplanet GJ 1214b using the 10.4 m Gran Telescopio Canarias (GTC) and the OSIRIS instrument. Using tuneable filters we observed a total of five transits, three of which were observed at two wavelengths nearly simultaneously, producing a total of eight individual light curves, six of these probed the possible existence of a methane absorption feature in the 8770 - 8850 {\\AA} region at high resolution. We detect no increase in the planet-to-star radius ratio across the methane feature with a change in radius ratio of $\\Delta$R = -0.0007 $\\pm$ 0.0017 corresponding to a scale height (H) change of -0.5 $\\pm$ 1.2 H across the methane feature, assuming a hydrogen dominated atmosphere. We find a variety of water and cloudy atmospheric models fit the data well, but find that cloud-free models provide poor fits. These observations support a flat transmission spectrum resulting from the presence of a high-altitude haze or a water-rich atmosphere, in agreement with ...

  12. Thermal Destruction of Spin-polaron Bands in the Narrow-gap Correlated Semiconductors FeGa3 and FeSb2

    SciTech Connect

    Petrovic C.; Storchak, V.G.; Brewer, J.S.; Lichti, R.L.; Hu, R.

    2012-04-05

    We report muon spin rotation spectra in the narrow-gap semiconductors FeGa{sub 3} and FeSb{sub 2} consistent with a narrow band of small spin polarons (SPs). The characteristic sizes obtained for these SPs are R{sub FeGa{sub 3}} {approx} 0.3-0.6 nm and R{sub FeSb{sub 2}} {approx} 0.3 nm, respectively. Such SP states are expected to originate from the exchange correlations between localized and itinerant electrons. Our data suggest that SP bands are formed at low temperature, but are destroyed by thermal fluctuations above 10 K in FeGa{sub 3} and above 7 K in FeSb{sub 2}. Formation of such SP band states can explain many of the low-temperature properties of these materials.

  13. Narrow-band Imagery with the Goddard Fabry-Perot: Probing the Epoch of Active Accretion for PMS Stars

    NASA Technical Reports Server (NTRS)

    Woodgate, Bruce E.; Grady, C.; Endres, M.; Williger, G.

    2006-01-01

    The STIS coronagraphic imaging sample of I'MS stars was surveyed with the Goddard Fabry-Perot (GFP) interferometer to determine what fraction of the stars drive jets, whether there is any difference in behavior for a group of intermediate-mass stars as compared with T Tauri stars, and to search for evolutionary effects. Compared to broad band imaging, the FGP achieves an emission-line nebulosity-to-star contrast gain of between 500 and 3000. To date, we have detected jets associated with classical T Tauri stars spanning a factor of 280 in mass accretion rate in approximately 50% of the STIS coronagraphic imaging sample. We also detected jets or Herbig-HARO knots associated with 5 Herbig Ae stars, all younger than 8 Myr, for a detection fraction which is smaller than the T Tauri survey.

  14. One-dimensional alumina photonic crystals with a narrow band gap and their applications to high-sensitivity concentration sensor and photoluminescence enhancement

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Wang, Jian; Li, Shou-Yi; Zhang, Jian-Wen; Wang, Cheng-Wei

    2015-10-01

    One-dimensional (1D) anodic aluminum oxide (AAO) photonic crystals (PCs) with alternate arrangement of stem channel layer and branched channel layer have been fabricated by using modified periodic pulse anodic technique with simple voltage waveform, and exhibited a narrow stop band with extreme low transmittance, steep edge. Their stop band is very sensitive to the concentration of NaCl solution, and the PCs are very suitable for concentration sensors. Importantly, it also is found that the photoluminescence (PL) intensity is enhanced remarkably when the PC structure was introduced into the AAO, which mainly attributes to the introduction of more PL centers into the branched channel layers, and the stop band also has effect on the PL intensity. Especially, the blue band edge of the stop band plays more important role on the PL enhancement of AAO.

  15. The X-ray spectrum and time variability of narrow emission line galaxies

    NASA Technical Reports Server (NTRS)

    Mushotzky, R.

    1981-01-01

    X-ray spectral and temporal observations are reported for six narrow emission line galaxies (NELGs), all of which are fitted by power-law X-ray spectra of energy slope 0.8 and have column densities in the line of sight greater than 1 x 10 to the 22nd atoms/sq cm. Three of the objects, NGC 526a, NGC 2110 and MCG-5-23-16 are variable in their X-ray flux, and the latter two, along with NGC 5506 and NGC 7582, showed detectable variability in at least one observation. The measured X-ray properties of these NELGs, which also included NGC 2992, strongly resemble those of previously-measured type 1 Seyferts of the same X-ray luminosity and lead to the conclusion of great similarity between the NELGs and low-luminosity type 1 Seyferts. The implications of these observations for the optical line-emitting region structure of these galaxies are discussed.

  16. Measurements of global UV irradiance at Terranova Bay, Antactica, by a home made narrow band filter radiometer

    NASA Astrophysics Data System (ADS)

    Salvatore, Scaglione; di Sarcina, Ilaria; Flori, Daniele; Menchini, Francesca

    2010-05-01

    Filter radiometers measure the solar radiation in several channels (typically 4 to 7) with a bandwith from 2 to 10 nm. They require less maintenance than the spectroradiometer and they are able to work in hostile environment as for instance the polar regions. The spectral resolution depends on the width at half maximum (FWHM) of the filters and is generally lower than the spectroradiometer resolution (0.5 nm). Other than the robustness of this instruments, the main advantage of the filter radiometers is the high frequency with which all wavelengths can be measured, making this class of instrument well suited for investigating short term irradiance variation. In this work is presented the results of UV irradiance measurements performed by a very narrow band (FWHM less than 1 nm) filter radiometer at Antarctica Italia Base, Mario Zucchelli Station, Terranova Bay, lat. 74° 41.6084' south and lon. 164° 05.9224' est. All-dielectric Fabry-Perot filters were manufactured in the laboratories of the Optical Coating Group, ENEA, by the ion beam assistance physical vapor deposition technique. Nine filters select nine different wavelengths in the UV spectral range from 296.5 nm to 377 nm with about 1 minute of measurement period, i.e. each wavelength is measured about 1250 times per day. At the moment the radiometer are permanently located near MZS and the data are daily downloaded in ENEA, Rome, by a dedicated satellite channel. During the Antarctica winter the radiometer will be in standby mode, in this season MZS is closed, and it will be start to measure again in the Antarctica spring.

  17. Ground-based Pa? Narrow-band Imaging of Local Luminous Infrared Galaxies. I. Star Formation Rates and Surface Densities

    NASA Astrophysics Data System (ADS)

    Tateuchi, Ken; Konishi, Masahiro; Motohara, Kentaro; Takahashi, Hidenori; Mitani Kato, Natsuko; Kitagawa, Yutaro; Todo, Soya; Toshikawa, Koji; Sako, Shigeyuki; Uchimoto, Yuka K.; Ohsawa, Ryou; Asano, Kentaro; Ita, Yoshifusa; Kamizuka, Takafumi; Komugi, Shinya; Koshida, Shintaro; Manabe, Sho; Nakamura, Tomohiko; Nakashima, Asami; Okada, Kazushi; Takagi, Toshinobu; Tanabé, Toshihiko; Uchiyama, Mizuho; Aoki, Tsutomu; Doi, Mamoru; Handa, Toshihiro; Kawara, Kimiaki; Kohno, Kotaro; Minezaki, Takeo; Miyata, Takashi; Morokuma, Tomoki; Soyano, Takeo; Tamura, Yoichi; Tanaka, Masuo; Tarusawa, Ken'ichi; Yoshii, Yuzuru

    2015-03-01

    Luminous infrared galaxies (LIRGs) are enshrouded by a large amount of dust produced by their active star formation, and it is difficult to measure their activity in optical wavelengths. We have carried out Pa? narrow-band imaging observations of 38 nearby star forming galaxies including 33 LIRGs listed in the IRAS Revised Bright Galaxy Sample catalog with the Atacama Near InfraRed camera on the University of Tokyo Atacama Observatory (TAO) 1.0 m telescope (miniTAO). Star formation rates (SFRs) estimated from the Pa? fluxes, corrected for dust extinction using the Balmer decrement method (typically AV ~ 4.3 mag), show a good correlation with those from the bolometric infrared luminosity of the IRAS data within a scatter of 0.27 dex. This suggests that the correction of dust extinction for the Pa? flux is sufficient in our sample. We measure the physical sizes and surface densities of infrared luminosities (? L(IR)) and the SFR (?SFR) of star forming regions for individual galaxies, and we find that most of the galaxies follow a sequence of local ultra-luminous or luminous infrared galaxies (U/LIRGs) on the L(IR)-? L(IR) and SFR-?SFR plane. We confirm that a transition of the sequence from normal galaxies to U/LIRGs is seen at L(IR) = 8 × 1010 L ?. Also, we find that there is a large scatter in physical size, different from normal galaxies or ULIRGs. Considering the fact that most U/LIRGs are merging or interacting galaxies, this scatter may be caused by strong external factors or differences in their merging stages.

  18. GTC OSIRIS transiting exoplanet atmospheric survey: detection of potassium in HAT-P-1b from narrow-band spectrophotometry

    NASA Astrophysics Data System (ADS)

    Wilson, P. A.; Sing, D. K.; Nikolov, N.; Lecavelier des Etangs, A.; Pont, F.; Fortney, J. J.; Ballester, G. E.; López-Morales, M.; Désert, J.-M.; Vidal-Madjar, A.

    2015-06-01

    We present the detection of potassium in the atmosphere of HAT-P-1b using optical transit narrow-band photometry. The results are obtained using the 10.4-m Gran Telescopio Canarias together with the OSIRIS instrument in tunable filter imaging mode. We observed four transits, two at continuum wavelengths outside the potassium feature, at 6792 and 8844 Å, and two probing the potassium feature in the line wing at 7582.0 Å and the line core at 7664.9 Å using a 12 Å filter width (R ˜ 650). The planet-to-star radius ratios in the continuum are found to be Rpl/R? = 0.1176 ± 0.0013 at 6792 Å and Rpl/R? = 0.1168 ± 0.0022 at 8844 Å, significantly lower than the two observations in the potassium line: Rpl/R? = 0.1248 ± 0.0014 in the line wing at 7582.0 Å and Rpl/R? = 0.1268 ± 0.0012 in the line core at 7664.9 Å. With a weighted mean of the observations outside the potassium feature Rpl/R? = 0.1174 ± 0.0010, the potassium is detected as an increase in the radius ratio of ?Rpl/R? = 0.0073 ± 0.0017 at 7582.0 Å and ?Rpl/R? = 0.0094 ± 0.0016 at 7664.9 Å (a significance of 4.3? and 6.1?, respectively). We hypothesize that the strong detection of potassium is caused by a large scaleheight, which can be explained by a high temperature at the base of the upper atmosphere. A lower mean molecular mass caused by the dissociation of molecular hydrogen into atomic hydrogen by the extreme ultraviolet flux from the host star may also partly explain the amplitude of our detection.

  19. A significant feature of microvessels in magnifying narrow-band imaging for diagnosis of early gastric cancer

    PubMed Central

    Kanesaka, Takashi; Uedo, Noriya; Yao, Kenshi; Ezoe, Yasumasa; Doyama, Hisashi; Oda, Ichiro; Kaneko, Kazuhiro; Kawahara, Yoshiro; Yokoi, Chizu; Sugiura, Yasushi; Ishikawa, Hideki; Kato, Minoru; Takeuchi, Yoji; Muto, Manabu; Saito, Yutaka

    2015-01-01

    Background and study aims: Magnifying narrow-band imaging (NBI) is more useful than conventional endoscopy for diagnosing early gastric cancer (EGC). However, evaluation of irregular microvascular patterns is subjective and is often difficult, even with expert eyes. The aim of this study was to clarify the most important microvascular patterns in magnifying NBI for diagnosis of EGC. Patients and methods: This was a post-hoc analysis of a multicenter prospective trial among nine Japanese hospitals. A total of 1353 patients underwent screening with white-light endoscopy and 362 patients had small (??10?mm) depressed lesions. They were randomly assigned to magnifying NBI or white-light endoscopy followed by magnifying NBI. During diagnosis, magnifying NBI images were recorded before biopsy. All magnifying NBI images were reviewed and evaluated for the association of four features of microvessels – that is, dilation, tortuosity, difference in caliber, and variation in shape – with cancer diagnosis. Results: Images of 343 lesions (40 cancerous and 303 benign depression lesions) were evaluable. The diagnostic performance (sensitivity/specificity) of each finding was: dilation, 25/90?%; tortuosity, 55/24?%; difference in caliber, 13?/99?%; and variation in shape, 70/95?%. Multivariate analysis identified only variation in shape as being statistically significantly associated with diagnosis of cancer (odds ratio 38.0, 95?% confidence interval: 16.1?–?95.7, P?

  20. A Catalog of z=3.1 Lyman Alpha Emitting Galaxies Discovered in Narrow-band Imaging of MUSYC 1030+05

    NASA Astrophysics Data System (ADS)

    Christenson, Holly; Gangolli, Nakul; Raney, Catie Ann; Walker, Jean P.; Gawiser, Eric J.; MUSYC Collaboration

    2016-01-01

    We present a catalog of ~200 Lyman Alpha Emitting galaxies (LAEs) at redshift z=3.1 found in a 5015 Å narrow-band image of the MUSYC 1030+05 field. We reduced raw optical images taken with the MOSAIC II CCD camera at the CTIO 4m telescope with the IRAF MSCRED package. The reduction included the crucial steps of bias subtraction, flat-field correction, cosmic ray and satellite trail rejection, astrometric calibration, tangent plane projection, weighted stacking, and sky background removal. Our initial catalog of sources detected in the narrow-band filter contains ~20,000 sources. We used additional photometric measurements in the MUSYC broad-band filters to identify LAEs via their flux density excess in the narrow-band. This catalog of LAEs will undergo further analysis to characterize how the number density, clustering, colors, and star formation rates of LAEs vary with position and evolve with redshift.We gratefully acknowledge support from NSF grants AST-1055919 & PHY-1263280.

  1. The Irkutsk Barium filter for narrow-band wide-field high-resolution solar images at the Dutch Open Telescope

    E-print Network

    Rutten, Rob

    1 The Irkutsk Barium filter for narrow-band wide-field high-resolution solar images at the Dutch ABSTRACT A wide-field birefringent filter for the barium II line at 455.4nm is developed in Irkutsk flanks of the line profile. The filter width is 0.008nm and the filter is tunable over 0.4nm through

  2. Synthesis of narrow band-gap III-V semiconductors using metal-organic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Jha, Smita

    The synthesis of narrow band gap materials in particular InAs, GaSb and InSb has been studied using metal-organic vapor phase epitaxy (MOVPE). Typically, for device applications these materials are grown on SI GaAs substrates. The integration of these materials with GaAs substrates through direct epitaxial growth is plagued by the high density of defects that are formed due to the 7-14% lattice mismatch between these materials. The presence of high density of threading dislocations in the resultant films has necessitated the development of approaches that alter the primary mechanisms of defect introduction and propagation, consequently leading to a reduction in the overall threading dislocation density during lattice-mismatched growths. Selective area epitaxy on nano-patterned substrates generated using block copolymer lithography was employed to nucleate the growing epitaxial material within specific mask openings and lead to strain relaxation within small islands. A significant improvement in material properties was observed for GaSb films grown on nano-patterned GaAs substrates at a very early stage of film growth. The FWHM of the GaSb peak grown on nano-patterned GaAs substrates was reduced by a factor of two or more relative to the films grown to the same thickness on non-patterned GaAs substrates. Defect mitigation was achieved for InAs growth on nano-patterned GaAs templates however, the resultant films exhibited a very different growth behavior when compared to GaSb growth on GaAs templates. While 200 mn thick GaSb film on nano-patterned GaAs substrates yielded a smooth, planar morphology, large islands were observed for InAs growth on nano-patterned GaAs templates. The difference in surface morphology between these systems was attributed to the enhanced surface diffusion of the indium adatoms combined with the kinetics of strain-relaxation leading to a disparity in island growth rate. From this study, it was determined that a balance between surface transport and strain-derived non-uniformity in island growth must be reached through careful choice of growth parameters for obtaining films with planar morphologies during lattice-mismatched integration.

  3. Narrow-band Imagery With The Goddard Fabry-Perot: Probing The Epoch Of Active Accretion For PMS Stars

    NASA Astrophysics Data System (ADS)

    Woodgate, Bruce E.; Grady, C.; Endres, M.; Hilton, G.; Williger, G.

    2006-06-01

    Over the past 5 years we surveyed the STIS coronagraphic imaging sample of PMS stars with the Goddard Fabry-Perot (GFP) interferometer at the Apache Point Observatory 3.5m telescope to determine what fraction of the stars drive jets, whether there is any difference in behavior for a group of intermediate-mass stars as compared with T Tauri stars, and to search for evolutionary effects. Compared to broad band imaging, the GFP achieves an emission-line nebulosity-to-star contrast gain of between 500 and 3000, depending upon choice of Fabry-Perot etalon, over a field which is 1.67' in radius. To date, we have detected jets associated with classical T Tauri stars spanning a factor of 280 in mass accretion rate in approximately 50% of the STIS coronagraphic imaging sample. Jets have not been detected in any of the stars with mass accretion rates less than 10$^{-8.5}$ solar masses/year, including objects with IR spectral energy distributions indicating deficits of warm, near-stellar dust. The GFP is also equipped with a simple Lyot coronagraph which allows us to search for similar outflows around brighter objects. To date, we have detected jets or Herbig-Haro knots associated with 5 Herbig Ae stars, all younger than 8 Myr, for a detection fraction which is similar to the T Tauri survey. No jets have been detected for Herbig Ae stars with IR SEDs indicating the presence of central cavities in the disks.

  4. The Chandra, Hubble Space Telescope, and VLA View of the Circumnuclear Extended Emission in the Narrow Emission Line Galaxy NGC 2110

    NASA Astrophysics Data System (ADS)

    Evans, Daniel A.; Lee, Julia C.; Kamenetska, Maria; Gallagher, Sarah C.; Kraft, Ralph P.; Hardcastle, Martin J.; Weaver, Kimberly A.

    2006-12-01

    We present results from new Chandra, archival Hubble Space Telescope (HST), and VLA imaging observations of the circumnuclear extended emission in the nearby Type 2 Seyfert galaxy NGC 2110. We find resolved soft-band X-ray emission ~4" (~160 pc) north of the nucleus, which is spatially coincident with [O III] emission, but lies just beyond the northern edge of the radio jet in the source. We find that shock heating of multiphase gas clouds can successfully account for this extended emission, although we cannot rule out alternative models, such as the scattering of nuclear radiation by ionized material, or pure photoionization from the nucleus. In addition, we detect kiloparsec-scale (~30") extended soft-band X-ray emission south of the nucleus. Finally, we compare our results for NGC 2110 with the prototypical type 2 Seyfert galaxy NGC 1068, and suggest that different physical processes could produce extended circumnuclear X-ray emission in Seyfert galaxies.

  5. Narrowing of band gap and effective charge carrier separation in oxygen deficient TiO2 nanotubes with improved visible light photocatalytic activity.

    PubMed

    Choudhury, Biswajit; Bayan, Sayan; Choudhury, Amarjyoti; Chakraborty, Purushottam

    2016-03-01

    Oxygen vacancies are introduced into hydrothermally processed TiO2 nanotube by vacuum calcination. Formation of oxygen vacancies modifies the local coordination in TiO2 as evident from Raman spectroscopy and secondary ion mass spectrometry (SIMS) results. The surface area is increased from 172.5m(2)/g in pure to 405.1m(2)/g in defective TiO2 nanotube. The mid-band gap electronic states created by oxygen vacancies are mostly responsible for the effective narrowing of band gap. Charge carrier separation is sufficiently prolonged as the charged oxygen defect states inhibit facile carrier recombination. With high surface area, narrowed band gap and separated charge carriers defective TiO2 nanotube is a suitable candidate in the photodegradation of methylene blue (MB) and phenol under visible light illumination. Photosensitized electron transfer from MB to the conduction band of TiO2 and the photodegradation of MB is facilitated in presence of high density of oxygen vacancies. Unlike MB, phenol absorbs in the UV region and does not easily excited under visible light. Phenol shows activity under visible light by forming charge transfer complex with TiO2. Defect trapped carriers become available at the phenol-TiO2 interface and finally interact with phenol molecule and degrade it. PMID:26629648

  6. Detection of marine methane emissions with AVIRIS band ratios

    NASA Astrophysics Data System (ADS)

    Bradley, Eliza S.; Leifer, Ira; Roberts, Dar A.; Dennison, Philip E.; Washburn, Libe

    2011-05-01

    The relative source contributions of methane (CH4) have high uncertainty, creating a need for local-scale characterization in concert with global satellite measurements. However, efforts towards methane plume imaging have yet to provide convincing results for concentrated sources. Although atmospheric CH4 mapping did not motivate the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) design, recent studies suggest its potential for studying concentrated CH4 sources such as the Coal Oil Point (COP) seep field (˜0.015 Tg CH4 yr-1) offshore Santa Barbara, California. In this study, we developed a band ratio approach on high glint COP AVIRIS data and demonstrate the first successful local-scale remote sensing mapping of natural atmospheric CH4 plumes. Plume origins closely matched surface and sonar-derived seepage distributions, with plume characteristics consistent with wind advection. Imaging spectrometer data may also be useful for high spatial-resolution characterization of concentrated, globally-significant CH4 emissions from offshore platforms and cattle feedlots.

  7. The Diffuse Interstellar Bands and Anomalous Microwave Emission May Originate from the Same Carriers

    NASA Astrophysics Data System (ADS)

    Bernstein, L. S.; Clark, F. O.; Cline, J. A.; Lynch, D. K.

    2015-11-01

    We argue that the observed spectroscopic and statistical properties of the diffuse interstellar band (DIB) carriers are those that are needed to produce the anomalous microwave emission (AME). We explore this idea using a carrier-impartial model for AME based on the observed DIB statistical properties. We show that an observed distribution of profile widths for narrow DIBs can be mapped into an AME spectrum. The mapping model is applied to width distributions observed for HD 204827 and HD 183143, selected because their spectroscopic and statistical properties bracket those for most other sight lines. The predicted AME spectra for these sight lines agree well with the range of spectral shapes, and peak frequencies, ?23–31 GHz, typically observed for AME. We use the AME spectral profiles to derive a strong constraint between the average carrier size and its rotational temperature. The constraint is applied to a variety of postulated molecular carrier classes, including polycyclic aromatic hydrocarbons, fulleranes, hydrocarbon chains, and amorphous hydrocarbon clusters. The constraint favors small, cold carriers with average sizes of ?8–15 carbon atoms, and average rotational temperatures of ?3–10 K, depending on carrier type. We suggest new observations, analyses, and modeling efforts to help resolve the ambiguities with regard to carrier size and class, and to further clarify the DIB–AME relationship.

  8. Using Lunar Observations to Assess Terra MODIS Thermal Emissive Bands Calibration

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Chen, Hongda

    2010-01-01

    MODIS collects data in both the reflected solar and thermal emissive regions using 36 spectral bands. The center wavelengths of these bands cover the3.7 to 14.24 micron region. In addition to using its on-board calibrators (OBC), which include a full aperture solar diffuser (SD) and a blackbody (BB), lunar observations have been scheduled on a regular basis to support both Terra and Aqua MODIS on-orbit calibration and characterization. This paper provides an overview of MODIS lunar observations and their applications for the reflective solar bands (RSB) and thermal emissive bands (TEB) with an emphasis on potential calibration improvements of MODIS band 21 at 3.96 microns. This spectral band has detectors set with low gains to enable fire detection. Methodologies are proposed and examined on the use of lunar observations for the band 21 calibration. Also presented in this paper are preliminary results derived from Terra MODIS lunar observations and remaining challenging issues.

  9. Probing the Ionization States of Polycyclic Aromatic Hydrocarbons via the 15-20 ?m Emission Bands

    NASA Astrophysics Data System (ADS)

    Shannon, M. J.; Stock, D. J.; Peeters, E.

    2015-10-01

    We report new correlations between ratios of band intensities of the 15-20 ?m emission bands of polycyclic aromatic hydrocarbons (PAHs) in a sample of 57 sources observed with the Spitzer/Infrared Spectrograph. This sample includes Large Magellanic Cloud point sources from the SAGE-Spec survey, nearby galaxies from the Spitzer Infrared Nearby Galaxies Survey survey, two Galactic interstellar medium cirrus sources, and the spectral maps of the Galactic reflection nebulae NGC 2023 and NGC 7023. We find that the 16.4, 17.4, and 17.8 ?m band intensities are inter-correlated in all environments. In NGC 2023 and NGC 7023 these bands also correlate with the 11.0 and 12.7 ?m band intensities. The 15.8 ?m band correlates only with the 15-18 ?m plateau and the 11.2 ?m emission. We examine the spatial morphology of these bands and introduce radial cuts. We find that these bands can be spatially organized into three sets: the 12.7, 16.4, and 17.8 ?m bands; the 11.2, 15.8 ?m bands and the 15-18 ?m plateau; and the 11.0 and 17.4 ?m bands. We also find that the spatial distribution of the 12.7, 16.4, and 17.8 ?m bands can be reconstructed by averaging the spatial distributions of the cationic 11.0 ?m and neutral 11.2 ?m bands. We conclude that the 17.4 ?m band is dominated by cations, the 15.8 ?m band by neutral species, and the 12.7, 16.4, and 17.8 ?m bands by a combination of the two. These results highlight the importance of PAH ionization for spatially differentiating sub-populations by their 15-20 ?m emission variability.

  10. Narrow He II emission in star-forming galaxies at low metallicity. Stellar wind emission from a population of very massive stars

    NASA Astrophysics Data System (ADS)

    Gräfener, G.; Vink, J. S.

    2015-06-01

    Context. In a recent study, star-forming galaxies with He ii ?1640 emission at moderate redshifts between 2 and 4.6 have been found to occur in two modes that are distinguished by the width of their He ii emission lines. Broad He ii emission has been attributed to stellar emission from a population of evolved Wolf-Rayet (WR) stars. The origin of narrow He ii emission is less clear but has been attributed to nebular emission excited by a population of very hot Pop III stars formed in pockets of pristine gas at moderate redshifts. Aims: We propose an alternative scenario for the origin of the narrow He ii emission, namely very massive stars (VMS) at low metallicity (Z), which form strong but slow WR-type stellar winds due to their proximity to the Eddington limit. Methods: We estimated the expected He ii line fluxes and equivalent widths based on wind models for VMS and Starburst99 population synthesis models and compared the results with recent observations of star-forming galaxies at moderate redshifts. Results: The observed He ii line strengths and equivalent widths are in line with what is expected for a population of VMS in one or more young super-clusters located within these galaxies. Conclusions: In our scenario the two observed modes of He ii emission originate from massive stellar populations in distinct evolutionary stages at low Z (~0.01 Z?). If this interpretation is correct, there is no need to postulate the existence of Pop III stars at moderate redshifts to explain the observed narrow He ii emission. An interesting possibility is the existence of self-enriched VMS with similar WR-type spectra at extremely low Z. Stellar He ii emission from such very early generations of VMS may be detectable in future studies of star-forming galaxies at high redshifts with the James Webb Space Telescope (JWST). The fact that the He ii emission of VMS is largely neglected in current population synthesis models will generally affect the interpretation of the integrated spectra of young stellar populations.

  11. DOUBLE-PEAKED NARROW EMISSION-LINE GALAXIES FROM THE SLOAN DIGITAL SKY SURVEY. I. SAMPLE AND BASIC PROPERTIES

    SciTech Connect

    Ge Junqiang; Hu Chen; Wang Jianmin; Zhang Shu; Bai Jinming

    2012-08-01

    Recently, much attention has been paid to double-peaked narrow emission-line (NEL) galaxies, some of which are suggested to be related to merging galaxies. We make a systematic search to build the largest sample of these sources from Data Release 7 of the Sloan Digital Sky Survey (SDSS). With reasonable criteria for fluxes, FWHMs of the emission lines, and separations of the peaks, we select 3030 double-peaked NEL galaxies. In light of the existence of broad Balmer lines and the locations of the two components of double-peaked NELs distinguished by the Kauffmann et al. criteria in the Baldwin-Phillips-Terlevich diagram, we find that there are 81 Type I active galactic nuclei (AGNs), 837 double Type II AGNs (2-Type II), 708 galaxies with double star-forming components (2-SF), 400 with mixed star-forming and Type II AGN components (Type II + SF), and 1004 unknown-type objects. As a by-product, a sample of galaxies (12,582) with asymmetric or top-flat profiles of emission lines is established. After visually inspecting the SDSS images of the two samples, we find 54 galaxies with dual cores. The present samples can be used to study the dynamics of merging galaxies, the triggering mechanism of black hole activity, the hierarchical growth of galaxies, and the dynamics of narrow line regions driven by outflows and a rotating disk.

  12. Investigation of band gap narrowing in nitrogen-doped La2Ti2O7 with transient absorption spectroscopy.

    PubMed

    Yost, Brandon T; Cushing, Scott K; Meng, Fanke; Bright, Joeseph; Bas, Derek A; Wu, Nianqiang; Bristow, Alan D

    2015-11-18

    Doping a semiconductor can extend the light absorption range, however, it usually introduces mid-gap states, reducing the charge carrier lifetime. This report shows that doping lanthanum dititinate (La2Ti2O7) with nitrogen extends the valence band edge by creating a continuum of dopant states, increasing the light absorption edge from 380 nm to 550 nm without adding mid-gap states. The dopant states are experimentally resolved in the excited state by correlating transient absorption spectroscopy with a supercontinuum probe and DFT prediction. The lack of mid-gap states is further confirmed by measuring the excited state lifetimes, which reveal the shifted band edge only increased carrier thermalization rates to the band edge and not interband charge recombination under both ultraviolet and visible excitation. Terahertz (time-domain) spectroscopy also reveals that the conduction mechanism remains unchanged after doping, suggesting the states are delocalized. PMID:26531849

  13. RFID Transponders' RF Emissions in Aircraft Communication and Navigation Radio Bands

    NASA Technical Reports Server (NTRS)

    Nguyen, Truong X.; Ely, Jay J.; Koppen Sandra V.; Fersch, Mariatheresa S.

    2008-01-01

    Radiated emission data in aircraft communication and navigation bands are presented for several active radio frequency identification (RFID) tags. The individual tags are different in design, operation and transmitting frequencies. The process for measuring the tags emissions in a reverberation chamber is discussed. Measurement issues dealing with tag interrogation, low level measurement in the presence of strong transmissions, and tags low duty factors are discussed. The results show strong emissions, far exceeding aircraft emission limits and can be of potential interference risks.

  14. Defect-Band Emission Photoluminescence Imaging on Multi-Crystalline Si Solar Cells: Preprint

    SciTech Connect

    Yan, F.; Johnston, S.; Zaunbrecher, K.; Al-Jassim, M.; Sidelkheir, O.; Blosse, A.

    2011-07-01

    Defect-band photoluminescence (PL) imaging with an InGaAs camera was applied to multicrystalline silicon (mc-Si) wafers, which were taken from different heights of different Si bricks. Neighboring wafers were picked at six different processing steps, from as-cut to post-metallization. By using different cut-off filters, we were able to separate the band-to-band emission images from the defect-band emission images. On the defect-band emission images, the bright regions that originate from the grain boundaries and defect clusters were extracted from the PL images. The area fraction percentage of these regions at various processing stages shows a correlation with the final cell electrical parameters.

  15. Estimation of band broadening in size-exclusion chromatography. I. A method based on analyzing narrow standards with a molar mass-sensitive detector.

    PubMed

    Yossen, Mariana M; Vega, Jorge R; Meira, Gregorio R

    2006-09-22

    A method is proposed for estimating the (asymmetrical and non-uniform) band broadening function (BBF) in size-exclusion chromatography (SEC). The following data are required: the molar mass calibration and the concentration- and molar mass chromatograms of a set of narrow standards. In the narrow range of each standard, the BBF is uniform but skewed. Each uniform BBF is estimated through a nonlinear optimization procedure that compares one (of the two) measured chromatograms with its theoretical prediction based on the other chromatogram. The method is validated with numerical examples that simulate the analyses of narrow standards exhibiting log-normal and Poisson weight chain length distributions. The BBF can be assumed of arbitrary shape, or represented by an exponentially-modified Gaussian (EMG). From the uniform BBF estimate, the true polydispersity of the standard can be determined. The global non-uniform BBF is obtained by interpolation between a set of uniform BBFs covering a wide range of elution volumes. PMID:16828786

  16. Shocked Post-starbust Galaxy Survey: Candidate Post-Starbust Galaxies with Narrow Emission Line Ratios Arising from Shocks

    NASA Astrophysics Data System (ADS)

    Cales, Sabrina; Alatalo, Katherine A.; Appleton, Philip N.; Lisenfeld, Ute; Rich, Jeffrey; Nyland, Kristina; Lacy, Mark; Kewley, Lisa J.

    2015-01-01

    As galaxies age they move from the blue cloud (star forming) to the red sequence (`dead' galaxies) in the color-magnitude diagram of galaxies. Galaxies between the blue cloud and red sequence (i.e., the green valley) are caught in the act of transitioning and they show large Balmer jump and high order Balmer absorption lines in their optical spectra. These galaxies answer to many names (i.e., E+A, K+A, Hdelta-strong, post-starburst), all with similar but slightly different selection criteria. Many studies of transitioning galaxies invoke strong constraints on emission lines in order to guarantee a dominant post-starburst (rather that actively star bursting) stellar population, however these constraints bias the sample against narrow-line emission not arising from star formation, namely active galactic nuclei, low-ionization nuclear emission regions and shocks. Using the Oh-Sarzi-Schawinski-Yi (OSSY) emission and absorption line measurements for SDSS DR7 galaxies we study the intersection between transitioning galaxies and those with shock line ratios. We show that a significant fraction of transitioning galaxies have emission-line ratios indicative of shocks. We postulate that these shocks may be in part responsible for the shepherding of blue star forming galaxies to passive early-types.

  17. Narrow-Band Imaging System for the Multi-application Solar Telescope at Udaipur Solar Observatory: Characterization of Lithium Niobate Etalons

    E-print Network

    Bayanna, A Raja; Venkatakrishnan, P; Srivastava, N

    2014-01-01

    Multi-application Solar Telescope is a 50 cm off-axis Gregorian telescope that has been installed at the lake site of Udaipur Solar Observatory. For quasi-simultaneous photospheric and chromospheric observations, a narrow-band imager has been developed as one of the back-end instruments for this telescope. Narrow-band imaging is achieved using two lithium niobate Fabry-Perot etalons working in tandem as a filter. This filter can be tuned to different wavelengths by changing either voltage, tilt or temperature of the etalons. To characterize the etalons, a Littrow spectrograph was set up, in conjunction with a 15 cm Carl Zeiss Coud\\'e solar telescope. The etalons were calibrated for the solar spectral lines FeI 6173 {\\AA}, and CaII 8542 {\\AA}. In this work, we discuss the characterization of the Fabry-Perot etalons, specifically the temperature and voltage tuning of the system for the spectral lines proposed for observations. We present the details of the calibration set-up and various tuning parameters. We al...

  18. Narrow band noise as a model of time-dependent accelerations - Study of the stability of a fluid surface in a microgravity environment

    NASA Technical Reports Server (NTRS)

    Casademunt, Jaume; Zhang, Wenbin; Vinals, Jorge; Sekerka, Robert F.

    1993-01-01

    We introduce a stochastic model to analyze in quantitative detail the effect of the high frequency components of the residual accelerations onboard spacecraft (often called g-jitter) on fluid motion. The residual acceleration field is modeled as a narrow band noise characterized by three independent parameters: its intensity G squared, a dominant frequency Omega, and a characteristic spectral width tau exp -1. The white noise limit corresponds to Omega tau goes to O, with G squared tau finite, and the limit of a periodic g-jitter (or deterministic limit) can be recovered for Omega tau goes to infinity, G squared finite. The analysis of the response of a fluid surface subjected to a fluctuating gravitational field leads to the stochastic Mathieu equation driven by both additive and multiplicative noise. We discuss the stability of the solutions of this equation in the two limits of white noise and deterministic forcing, and in the general case of narrow band noise. The results are then applied to typical microgravity conditions.

  19. 608 W average power picosecond all fiber polarization-maintained amplifier with narrow-band and near-diffraction-limited beam quality

    NASA Astrophysics Data System (ADS)

    Ma, Pengfei; Tao, Rumao; Huang, Long; Wang, Xiaolin; Zhou, Pu; Liu, Zejin

    2015-07-01

    In this manuscript, we focus on a narrow-band all fiber polarization-maintained (PM) master oscillator power amplifier (MOPA) configuration seeded by a narrow band gain-switched laser diode for near-diffraction-limited average power scaling in sub-nanosecond pulsed regime by controlling detrimental mode instability (MI) effect. The MI free average power scaling abilities of the MOPA system with different pumping wavelengths are explored experimentally. By pumping the main amplifier with 976 nm laser diodes (LDs), experimental results show that near-diffraction-limited average power is just limited to be about 380 W due to the influence of MI effect. However, by selecting a 915 nm pumping wavelength, a mode-instability free average power of 608 W is achieved with pulse width of ?810 ps, peak power of ?128 kW and pulse energy of 60.8 ?J. At 608 W average power, the 3 dB line-width of the whole MOPA configuration is measured to be about 0.19 nm. The beam quality (M2 factor) and polarization extinction ratio (PER) at maximal output power are measured to be within 1.4 and 13 dB, respectively.

  20. Band-gap narrowing and magnetic behavior of Ni-doped Ba(Ti0.875Ce0.125)O3 thin films

    NASA Astrophysics Data System (ADS)

    Zhou, Wenliang; Deng, Hongmei; Yu, Lu; Yang, Pingxiong; Chu, Junhao

    2015-11-01

    Band-gap narrowing and magnetic effects have been observed in a Ni-doped Ba(Ti0.875Ce0.125)O3 (BTC) thin film. Structural characterizations and microstructural analysis show that the as-prepared Ba(Ti0.75Ce0.125Ni0.125)O3-? (BTCN) thin film exhibits a cubic perovskite structure with an average grain size of 25?nm. The Ce doping at the Ti-site results in an increasing perovskite volume to favour an O-vacancy-stabilized Ni2+ substitution. Raman spectroscopy, however, shows the cubic symmetry of crystalline structures is locally lowered by the presence of dopants, significantly deviating from the ideal Pm3m space group. Moreover, BTCN presents a narrowed band-gap, much smaller than that of BaTiO3 and BTC, due to new states of both the highest occupied molecular orbital and the lowest unoccupied molecular orbital in an electronic structure with the presence of Ni. Also, magnetic enhancement driven by co-doping has been confirmed in the films, which mainly stems from the exchange interaction of Ni2+ ions via an electron trapped in a bridging oxygen vacancy. These findings may open an avenue to discover and design optimal perovskite compounds for solar-energy devices and information storage.

  1. Valence Band X-Ray Emission Spectra of Compressed Germanium Viktor V. Struzhkin,1

    E-print Network

    Lin, Jung-Fu "Afu"

    Valence Band X-Ray Emission Spectra of Compressed Germanium Viktor V. Struzhkin,1 Ho-kwang Mao,1 the electron self-energy [3­10]. The pre- dicted band broadening is only 0.05 eV in germanium and 0.08 e

  2. Unprecedentedly Strong and Narrow Electromagnetic Emissions Stimulated by High-Frequency Radio Waves in the Ionosphere

    SciTech Connect

    Norin, L.; Leyser, T. B.; Nordblad, E.; Thide, B.; McCarrick, M.

    2009-02-13

    Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

  3. Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere.

    PubMed

    Norin, L; Leyser, T B; Nordblad, E; Thidé, B; McCarrick, M

    2009-02-13

    Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA. PMID:19257596

  4. Narrow Band Source of Transform-Limited Photon Pairs via Four-Wave Mixing in a Cold Atomic Ensemble

    E-print Network

    Bharath Srivathsan; Gurpreet Kaur Gulati; Chng Mei Yuen Brenda; Gleb Maslennikov; Dzmitry Matsukevich; Christian Kurtsiefer

    2013-09-18

    We observe narrowband pairs of time-correlated photons of wavelengths 776\\,nm and 795\\,nm from non-degenerate four-wave mixing in a laser-cooled atomic ensemble of $^{87}${Rb} using a cascade decay scheme. Coupling the photon pairs into single mode fibers, we observe an instantaneous rate of 7700 pairs per second with silicon avalanche photodetectors, and an optical bandwidth below 30\\,MHz. Detection events exhibit a strong correlation in time ($g^{(2)}(\\tau=0)\\approx5800$), and a high coupling efficiency indicated by a pair-to-single ratio of 23%. The violation of the Cauchy-Schwarz inequality by a factor of $8.4\\times10^6$ indicates a strong non-classical correlation between the generated fields, while a Hanbury--Brown--Twiss experiment in the individual photons reveals their thermal nature. The narrow bandwidth and brightness of our source makes it ideal for interacting with atomic ensembles in quantum communication protocols.

  5. Compact source of narrow-band counterpropagating polarization-entangled photon pairs using a single dual-periodically poled crystal

    E-print Network

    Yan-Xiao Gong; Zhen-Da Xie; Ping Xu; Xiao-Qiang Yu; Peng Xue; Shi-Ning Zhu

    2011-12-20

    We propose a scheme for the generation of counterpropagating polarization-entangled photon pairs from a dual-periodically poled crystal. Compared with the usual forward-wave type source, this source, in the backward-wave way, has a much narrower bandwidth. With a 2-cm-long bulk crystal, the bandwidths of the example sources are estimated to be 3.6 GHz, and the spectral brightnesses are more than 100 pairs/(s GHz mW). Two concurrent quasi-phase-matched spontaneous parametric down-conversion processes in a single crystal enable our source to be compact and stable. This scheme does not rely on any state projection and applies to both degenerate and non-degenerate cases, facilitating applications of the entangled photons.

  6. Three-photon-induced blue emission with narrow bandwidth from hot flower-like ZnO nanorods.

    PubMed

    Dai, Jun; Yuan, Mao-Hui; Zeng, Jian-Hua; Dai, Qiao-Feng; Lan, Sheng; Xiao, Chai; Tie, Shao-Long

    2015-11-01

    ZnO nanorods (NRs) self-organized into flowers were synthesized at different temperatures ranging from 100°C to 180°C by using the hydrothermal method. The existence of Zn interstitials (Zni) was confirmed by X-ray photoelectron spectroscopy and a larger amount of Zni was found in the ZnO NRs prepared at higher temperatures. A redshift of the emission peak of more than 15 nm was observed for the ZnO NRs under single photon excitation. The nonlinear optical properties of the flower-like ZnO NRs were characterized by using focused femtosecond laser light and strong three-photon-induced luminescence was observed at an excitation wavelength of ~750 nm. More interestingly, a large redshift of the emission peak was observed with increasing excitation intensity, resulting in efficient blue emission with a narrow bandwidth of ~30 nm. It was confirmed that the large redshift originates from the heating of the ZnO NRs to a temperature of more than 800°C and the closely packed ZnO NRs in the flowers play a crucial role in heat accumulation. The stable and efficient three-photon-induced blue emission from such ZnO NRs may find potential applications in the fields of optical display, high-temperature sensors and light therapy of tumors. PMID:26561193

  7. The narrow ultraviolet emission lines of the red dwarf Au Microscopii (dM1.6e)

    NASA Technical Reports Server (NTRS)

    Ayres, T. R.; Eriksson, K.; Linsky, J. L.; Stencel, R. E.

    1983-01-01

    It is pointed out that the red dwarfs are the smallest, coolest, faintest, least massive, but most common of normal main-sequence stars. The dMe (H-alpha emission) subclass of the red dwarfs exhibits the largest median soft X-ray to bolometric luminosity ratio of any group of late-type stars. In connection with the present investigation, attention is given to the first high-dispersion spectra of the chromospheric (6000 K) and higher temperature (up to 100,000 K) emissions of a dMe star, AU Microscopii in the far-ultraviolet (1150-2000 A) and middle-ultraviolet (2000-3000 A) bands accessible to the International Ultraviolet Explorer (IUE). AU Mic is one of the most luminous of lower main-sequence stars in C IV and soft X-ray emission.

  8. Band Structure of ZnO from Resonant X-ray Emission Spectroscopy

    SciTech Connect

    Preston, A.; Ruck, B; Piper, L; DeMasi, A; Smith, K; Schleife, A; Fuchs, F; Bechstedt, F; Chai, J; Durbin, S

    2008-01-01

    Soft x-ray emission and absorption spectroscopy of the O K-edge are employed to investigate the electronic structure of wurtzite ZnO(0001). A quasiparticle band structure calculated within the GW approximation agrees well with the data, most notably with the energetic location of the Zn 3d-O 2p hybridized state and the anisotropy of the absorption spectra. Dispersion in the band structure is mapped using the coherent k-selective part of the resonant x-ray emission spectra. We show that a more extensive mapping of the bands is possible in the case of crystalline anisotropy such as that found in ZnO.

  9. A coronagraphic absorbing cloud reveals the narrow-line region and extended Lyman ? emission of QSO J0823+0529

    NASA Astrophysics Data System (ADS)

    Fathivavsari, H.; Petitjean, P.; Noterdaeme, P.; Pâris, I.; Finley, H.; López, S.; Srianand, R.; Sánchez, P.

    2015-11-01

    We report long-slit spectroscopic observations of the quasar SDSS J082303.22+052907.6 (z_{C IV}} ˜ 3.1875), whose broad-line region (BLR) is partly eclipsed by a strong damped Lyman ? (DLA; logN(H I) = 21.7) cloud. This allows us to study the narrow-line region (NLR) of the quasar and the Lyman ? emission from the host galaxy. Using CLOUDY models that explain the presence of strong N V and P V absorption together with the detection of Si II* and O I** absorption in the DLA, we show that the density and the distance of the cloud to the quasar are in the ranges 180 < nH < 710 cm-3 and 580 > r0 > 230 pc, respectively. Sizes of the neutral (˜2-9pc) and highly ionized phases (˜3-80pc) are consistent with the partial coverage of the C IV BLR by the C IV absorption from the DLA (covering factor of ˜0.85). We show that the residuals are consistent with emission from the NLR with C IV/Lyman ? ratios varying from 0 to 0.29 through the profile. Remarkably, we detect extended Lyman ? emission up to 25 kpc to the north and west directions and 15 kpc to the south and east. We interpret the emission as the superposition of strong emission in the plane of the galaxy up to 10 kpc with emission in a wind of projected velocity ˜500 km s-1 which is seen up to 25 kpc. The low metallicity of the DLA (0.27 solar) argues for at least part of this gas being infalling towards the active galactic nucleus and possibly being located where accretion from cold streams ends up.

  10. Subarcsec emission in Seyfert galaxies the nuclear component in the L- and M-bands

    E-print Network

    Prieto, M A; Kotilainen, J K

    2002-01-01

    We present deep L- and M- band imaging with ISAAC on the ESO VLT with unprecedented spatial resolution of the nearby Seyfert 2 galaxies NGC 7496 and NGC 7582 and the Seyfert 1 galaxy NGC 7213. The unresolved nuclear component dominates the emission within the central 90 pc region, while the host galaxy accounts for up to 50 % of the integrated emission at both wavelengths within the detected sizes of of 1 kpc in the L-band and 0.5 kpc in the M-band. The overall morphology of the extended component follows the general isophote pattern defined by the near-infrared continuum of the galaxies. However, the central 300 pc regions show much more ordered elliptical isophotes than in the near-infrared. In particular, emission in the L- and M-bands shows well defined central point sources in the two Seyfert 2s.

  11. Techniques to minimize adjacent band emissions from Earth Exploration Satellites to protect the Space Research (Category B) Earth Stations in the 8400-8450 MHz band

    NASA Technical Reports Server (NTRS)

    Wang, Charles C.; Sue, Miles K.; Manshadi, Farzin

    2004-01-01

    The Earth Exploration Satellites operating in the 8025-8400 MHz band can have strong adjacent band emissions on the8400-8450 MHz band which is allocated for Space Research (Category-B). The unwanted emission may exceed the protection criterion establish by the ITU-R for the protection of the Space Research (Category B) earth stations, i.e., deep-space earth stations. An SFCG Action Item (SF 23/14) was created during the 23rd SFCG meeting to explore technical and operational techniques to reduce the adjacent band emissions. In response to this action item, a study was conducted and results are presented in this document.

  12. Enhancement in UV emission and band gap by Fe doping in ZnO thin films

    NASA Astrophysics Data System (ADS)

    Srivastava, Anchal; Kumar, Nishant; Khare, Sanjay

    2014-03-01

    Enhancement of the optical band gap of ZnO from 3.14 to 3.29 eV has been obtained using Fe dopant. Undoped and doped ZnO films are deposited by sol-gel spin coating. XRD patterns indicate polycrystalline nature and hexagonal wurtzite structure of Zn1-xFexO films. EDX analysis confirms the presence of iron dopant. The photoluminescence spectra show an ultraviolet emission peak at 398 nm (NBE emission) and defect emission peak at 485 nm. Intensity of the NBE emission is much higher for the doped samples with its ratio to defect emission intensity highest for 2 at. %doping. The NBE emission shifts to higher energy with increasing dopant concentration in a manner similar to that exhibited by the band gap. Surface morphology has been studied using FESEM.

  13. Accretion disk/corona emission from a radio-loud narrow line Seyfert 1 galaxy PKS 0558-504

    E-print Network

    Ghosh, R; Raychaudhuri, B

    2015-01-01

    Approximately 10-20% of Active Galactic Nuclei are known to eject powerful jets from the innermost regions. There is very little observational evidence if the jets are powered by spinning black holes and if the accretion disks extend to the innermost regions in radio-loud AGN. Here we study the soft X-ray excess, the hard X-ray spectrum and the optical/UV emission from the radio-loud narrow-line Seyfert 1 galaxy PKS 0558-504 using Suzaku and Swift observations. The broadband X-ray continuum of PKS 0558- 504 consists of a soft X-ray excess emission below 2 keV that is well described by a blackbody (kTe ~ 0.13 keV) and high energy emission that is well described by a thermal Comptonisation (compps) model with kTe ~ 250 keV, optical depth {\\tau} ~ 0.05 (spherical corona) or kTe ~ 90 keV, {\\tau} ~ 0.5 (slab corona). The Comptonising corona in PKS 0558-504 is likely hotter than in radio-quiet Seyferts such as IC 4329A and Swift J2127.4+5654. The observed soft X-ray excess can be modelled as blurred reflection from...

  14. Anatomy of the AGN in NGC 5548: V. A clear view of the X-ray narrow emission lines

    E-print Network

    Whewell, M; Kaastra, J S; Mehdipour, M; Steenbrugge, K C; Bianchi, S; Behar, E; Ebrero, J; Cappi, M; Costantini, E; De Marco, B; Di Gesu, L; Kriss, G A; Paltani, S; Peterson, B M; Petrucci, P -O; Pinto, C; Ponti, G

    2015-01-01

    Context. Our consortium performed an extensive multi-wavelength campaign of the nearby Seyfert 1 galaxy NGC 5548 in 2013-14. The source appeared unusually heavily absorbed in the soft X-rays, and signatures of outflowing absorption were also present in the UV. He-like triplets of neon, oxygen and nitrogen, and radiative recombination continuum (RRC) features were found to dominate the soft X-ray spectrum due to the low continuum flux. Aims. Here we focus on characterising these narrow emission features using data obtained from the XMM-Newton RGS (770 ks stacked spectrum). Methods. We use SPEX for our initial analysis of these features. Self-consistent photoionisation models from Cloudy are then compared with the data to characterise the physical conditions of the emitting region. Results. Outflow velocity discrepancies within the O VII triplet lines can be explained if the X-ray narrow-line region (NLR) in NGC 5548 is absorbed by at least one of the six warm absorber components found by previous analyses. The...

  15. 33 W quasi-continuous-wave narrow-band sodium D2a laser by sum-frequency generation in LBO

    NASA Astrophysics Data System (ADS)

    Wang, Peng-Yuan; Xie, Shi-Yong; Bo, Yong; Wang, Bao-Shan; Zuo, Jun-Wei; Wang, Zhi-Chao; Shen, Yu; Zhang, Feng-Feng; Wei, Kai; Jin, Kai; Xu, Yi-Ting; Xu, Jia-Lin; Peng, Qin-Jun; Zhang, Jing-Yuan; Lei, Wen-Qiang; Cui, Da-Fu; Zhang, Yu-Dong; Xu, Zu-Yan

    2014-09-01

    We demonstrate an all-solid quasi-continuous-wave (QCW) narrow-band source tunable to sodium D2a line at 589.159 nm. The source is based on sum-frequency mixing between lasers at 1064 nm and 1319 nm in a LBO crystal. The 1064 nm and 1319 nm lasers are produced from two diode side-pumped Nd:YAG master oscillator power amplifier (MOPA) laser systems, respectively. A 33 W output of 589 nm laser is obtained with beam quality factor M2 = 1.25, frequency stability better than ±0.2 GHz and linewidth less than 0.44 GHz. A prototype 589 nm laser system is assembled, and a sodium laser guided star has been successfully observed in the field test.

  16. Searching for correlations in simultaneous X-ray and UV emission in the narrow-line Seyfert 1 galaxy 1H 0707-495

    NASA Astrophysics Data System (ADS)

    Robertson, D. R. S.; Gallo, L. C.; Zoghbi, A.; Fabian, A. C.

    2015-11-01

    We examine simultaneous X-ray and UV light curves from multi-epoch 8 d XMM-Newton observations of the narrow line Seyfert 1 galaxy 1H 0707-495. The simultaneous observations reveal that both X-ray and UV emission are variable and that the amplitude of the X-ray variations is significantly greater than that of the UV variations in both epochs. Using a discrete correlation function the X-ray and UV light curves were examined for correlation on time-scales up to 7 d. Low-significance (˜95 per cent confidence) correlations with the UV leading the X-ray variations are observed. The lack of a significant correlation between the UV and X-ray bands seems consistent with the X-ray source being centrally compact and dominated by light bending close to the black hole. In addition, multiband X-ray light curves were examined for correlations on similar time-scales. Highly significant (>99.9 per cent confidence) correlations were observed at zero lag consistent with previous studies of this active galactic nucleus.

  17. A Direct Linkage Between AGN Outflows in The Narrow-line Regions and The X-ray Emission From The Accretion disks

    E-print Network

    Wang, J; Wei, J Y

    2015-01-01

    The origin of outflow in narrow-line region (NLR) of active galactic nucleus (AGN) is studied in this paper by focusing on the relationship between the [\\ion{O}{3}]$\\lambda$5007 line profile and the hard X-ray (in a bandpass of 2-10 keV) emission from the central SMBH in type-I AGNs. A sample of 47 local X-ray selected type-I AGNs at $zenergy band from 2 to 10keV of these luminous AGNs range from $10^{42}$ to $10^{44}\\ \\mathrm{erg\\ s^{-1}}$. A joint spectral analysis is performed on their optical and X-ray spectra, in which the [\\ion{O}{3}] line profile is modeled by a sum of several Gaussian functions to quantify its deviation from a pure Gaussian function. The statistics allows us to identify a moderate correlation with a significance level of 2.78$\\sigma$: luminous AGNs with stronger [\\ion{O}{3}] blue asymmetry tend to have steeper hard X-ray spectra. By identifying a role of ...

  18. Amplified spontaneous emission measurement of a line-narrowed, tunable, Ti:Al2O3 amplifier using rubidium absorption

    NASA Technical Reports Server (NTRS)

    Barnes, James C.; Barnes, Norman P.; Lockard, George E.; Cross, Patricia L.

    1989-01-01

    Amplified spontaneous emission, ASE, generated by a Ti:Al2O3 laser amplifier has been measured as a function of pump energy, and thus gain, using the atomic absorption of rubidium, Rb, gas at 0.780 micron. By tuning the Ti:Al2O3 laser, the Rb cell could selectively absorb the narrow spectral bandwidth laser radiation while transmitting the wide spectral bandwidth ASE. Transmission of laser amplifier pulses through a Rb absorption cell, measured at various temperatures, thus allows the measurement of the weak ASE in the vicinity of the strong laser pulse. A model for the transmission of Rb as a function of temperature and wavelength has been developed. The measured transmissions are in good agreement with the transmission model predictions.

  19. Ortho-Rectification of Narrow Band Multi-Spectral Imagery Assisted by Dslr RGB Imagery Acquired by a Fixed-Wing Uas

    NASA Astrophysics Data System (ADS)

    Rau, J.-Y.; Jhan, J.-P.; Huang, C.-Y.

    2015-08-01

    Miniature Multiple Camera Array (MiniMCA-12) is a frame-based multilens/multispectral sensor composed of 12 lenses with narrow band filters. Due to its small size and light weight, it is suitable to mount on an Unmanned Aerial System (UAS) for acquiring high spectral, spatial and temporal resolution imagery used in various remote sensing applications. However, due to its wavelength range is only 10 nm that results in low image resolution and signal-to-noise ratio which are not suitable for image matching and digital surface model (DSM) generation. In the meantime, the spectral correlation among all 12 bands of MiniMCA images are low, it is difficult to perform tie-point matching and aerial triangulation at the same time. In this study, we thus propose the use of a DSLR camera to assist automatic aerial triangulation of MiniMCA-12 imagery and to produce higher spatial resolution DSM for MiniMCA12 ortho-image generation. Depending on the maximum payload weight of the used UAS, these two kinds of sensors could be collected at the same time or individually. In this study, we adopt a fixed-wing UAS to carry a Canon EOS 5D Mark2 DSLR camera and a MiniMCA-12 multi-spectral camera. For the purpose to perform automatic aerial triangulation between a DSLR camera and the MiniMCA-12, we choose one master band from MiniMCA-12 whose spectral range has overlap with the DSLR camera. However, all lenses of MiniMCA-12 have different perspective centers and viewing angles, the original 12 channels have significant band misregistration effect. Thus, the first issue encountered is to reduce the band misregistration effect. Due to all 12 MiniMCA lenses being frame-based, their spatial offsets are smaller than 15 cm and all images are almost 98% overlapped, we thus propose a modified projective transformation (MPT) method together with two systematic error correction procedures to register all 12 bands of imagery on the same image space. It means that those 12 bands of images acquired at the same exposure time will have same interior orientation parameters (IOPs) and exterior orientation parameters (EOPs) after band-to-band registration (BBR). Thus, in the aerial triangulation stage, the master band of MiniMCA-12 was treated as a reference channel to link with DSLR RGB images. It means, all reference images from the master band of MiniMCA-12 and all RGB images were triangulated at the same time with same coordinate system of ground control points (GCP). Due to the spatial resolution of RGB images is higher than the MiniMCA-12, the GCP can be marked on the RGB images only even they cannot be recognized on the MiniMCA images. Furthermore, a one meter gridded digital surface model (DSM) is created by the RGB images and applied to the MiniMCA imagery for ortho-rectification. Quantitative error analyses show that the proposed BBR scheme can achieve 0.33 pixels of average misregistration residuals length and the co-registration errors among 12 MiniMCA ortho-images and between MiniMCA and Canon RGB ortho-images are all less than 0.6 pixels. The experimental results demonstrate that the proposed method is robust, reliable and accurate for future remote sensing applications.

  20. Discovery of SiO Band Emission from Galactic B[e] Supergiants

    NASA Astrophysics Data System (ADS)

    Kraus, M.; Oksala, M. E.; Cidale, L. S.; Arias, M. L.; Torres, A. F.; Borges Fernandes, M.

    2015-02-01

    B[e] supergiants (B[e]SGs) are evolved massive stars in a short-lived transition phase. During this phase, these objects eject large amounts of material, which accumulate in a circumstellar disk-like structure. The expelled material is typically dense and cool, providing the cradle for molecule and dust condensation and for a rich, ongoing chemistry. Very little is known about the chemical composition of these disks, beyond the emission from dust and CO revolving around the star on Keplerian orbits. As massive stars preserve an oxygen-rich surface composition throughout their life, other oxygen-based molecules can be expected to form. As SiO is the second most stable oxygen compound, we initiated an observing campaign to search for first-overtone SiO emission bands. We obtained high-resolution near-infrared L-band spectra for a sample of Galactic B[e]SGs with reported CO band emission. We clearly detect emission from the SiO first-overtone bands in CPD-52 9243 and indications for faint emission in HD 62623, HD 327083, and CPD-57 2874. From model fits, we find that in all these stars the SiO bands are rotationally broadened with a velocity lower than observed in the CO band forming regions, suggesting that SiO forms at larger distances from the star. Hence, searching for and analyzing these bands is crucial for studying the structure and kinematics of circumstellar disks, because they trace complementary regions to the CO band formation zone. Moreover, since SiO molecules are the building blocks for silicate dust, their study might provide insight in the early stage of dust formation. Based on observations collected with the ESO VLT Paranal Observatory under program 093.D-0248(A).

  1. Origin of multi-band emission from the microquasar Cygnus X-1

    SciTech Connect

    Zhang, Jianfu; Lu, Jufu; Xu, Bing

    2014-06-20

    We study the origin of non-thermal emissions from the Galactic black hole X-ray binary Cygnus X-1, which is a confirmed high-mass microquasar. By analogy with the methods used in studies of active galactic nuclei, we propose a two-dimensional, time-dependent radiation model from the microquasar Cygnus X-1. In this model, the evolution equation for relativistic electrons in a conical jet are numerically solved by including escape, adiabatic, and various radiative losses. The radiative processes involved are synchrotron emission, its self-Compton scattering, and inverse Compton scatterings of an accretion disk and its surrounding stellar companion. This model also includes an electromagnetic cascade process of an anisotropic ?-? interaction. We study the spectral properties of electron evolution and its emission spectral characteristic at different heights of the emission region located in the jet. We find that radio data from Cygnus X-1 are reproduced by the synchrotron emission, the Fermi Large Area Telescope measurements by the synchrotron emission and Comptonization of photons of the stellar companion, and the TeV band emission fluxes by the Comptonization of the stellar photons. Our results show the following. (1) The radio emission region extends from the binary system scales to the termination of the jet. (2) The GeV band emissions should originate from the distance close to the binary system scales. (3) The TeV band emissions could be inside the binary system, and these emissions could be probed by the upcoming Cherenkov Telescope Array. (4) The MeV tail emissions, which produce a strongly linearly polarized signal, are emitted inside the binary system. The location of the emissions is very close to the inner region of the jet.

  2. Origin of yellow-band emission in epitaxially grown GaN nanowire arrays.

    PubMed

    Liu, Baodan; Yuan, Fang; Dierre, Benjamin; Sekiguchi, Takashi; Zhang, Song; Xu, Yongkuan; Jiang, Xin

    2014-08-27

    Here, we report the origin of the yellow-band emission in epitaxial GaN nanowire arrays grown under carbon-free conditions. GaN nanowires directly grown on [0001]-oriented sapphire substrate exhibit an obvious and broad yellow-band in the visible range 400-800 nm, whereas the insertion of Al/Au layers in GaN-sapphire interface significantly depresses the visible emission, and only a sharp peak in the UV range (369 nm) can be observed. The persuasive differences in cathodoluminescence provide direct evidence for demonstrating that the origin of the yellow-band emission in GaN nanowire arrays arises from dislocation threading. The idea using buffering/barrier layers to isolate the dislocation threading in epitaxially grown GaN nanowires can be extended to the rational synthesis and structural defect controlling of a wide range of semiconductor films and nanostructures with superior crystal quality and excellent luminescence property. PMID:25057903

  3. Bulk band gaps in divalent hexaborides: A soft x-ray emission study

    SciTech Connect

    Denlinger, Jonathan D.; Gweon, Gey-Hong; Allen, James W.; Bianchi, Andrea D.; Fisk, Zachary

    2001-10-03

    Boron K-edge soft x-ray emission and absorption are used to address the fundamental question of whether divalent hexaborides are intrinsic semimetals or defect-doped bandgap insulators. These bulk sensitive measurements, complementary and consistent with surface-sensitive angle-resolved photoemission experiments, confirm the existence of a bulk band gap and the location of the chemical potential at the bottom of the conduction band.

  4. Ocean Surface Emissivity at L-band (1.4 GHz): The Dependence on Salinity and Roughness

    NASA Technical Reports Server (NTRS)

    LeVine, D. M.; Lang, R.; Wentz, F.; Messiner, T.

    2012-01-01

    A characterization of the emissivity of sea water at L-band is important for the remote sensing of sea surface salinity. Measurements of salinity are currently being made in the radio astronomy band at 1.413 GHz by ESA's Soil Moisture and Ocean Salinity (SMOS) mission and NASA's Aquarius instrument aboard the Aquarius/SAC-D observatory. The goal of both missions is accuracy on the order of 0.1 psu. This requires accurate knowledge of the dielectric constant of sea water as a function of salinity and temperature and also the effect of waves (roughness). The former determines the emissivity of an ideal (i.e. flat) surface and the later is the major source of error from predictions based on a flat surface. These two aspects of the problem of characterizing the emissivity are being addressed in the context of the Aquarius mission. First, laboratory measurements are being made of the dielectric constant of sea water. This is being done at the George Washington University using a resonant cavity. In this technique, sea water of known salinity and temperature is fed into the cavity along its axis through a narrow tube. The sea water changes the resonant frequency and Q of the cavity which, if the sample is small enough, can be related to the dielectric constant of the sample. An extensive set of measurements have been conducted at 1.413 GHz to develop a model for the real and imaginary part of the dielectric constant as a function of salinity and temperature. The results are compared to the predictions of models based on parameterization of the Debye resonance of the water molecule. The models and measurements are close; however, the differences are significant for remote sensing of salinity. This is especially true at low temperatures where the sensitivity to salinity is lowest.

  5. Detecting long-duration narrow-band gravitational wave transients associated with soft gamma repeater quasiperiodic oscillations

    NASA Astrophysics Data System (ADS)

    Murphy, David; Tse, Maggie; Raffai, Peter; Bartos, Imre; Khan, Rubab; Márka, Zsuzsa; Matone, Luca; Redwine, Keith; Márka, Szabolcs

    2013-05-01

    We have performed an in-depth concept study of a gravitational wave data analysis method which targets repeated long quasimonochromatic transients (triggers) from cosmic sources. The algorithm concept can be applied to multitrigger data sets in which the detector-source orientation and the statistical properties of the data stream change with time, and does not require the assumption that the data is Gaussian. Reconstructing or limiting the energetics of potential gravitational wave emissions associated with quasiperiodic oscillations observed in the x-ray lightcurve tails of soft gamma repeater flares might be an interesting endeavor of the future. Therefore we chose this in a simplified form to illustrate the flow, capabilities, and performance of the method. We investigate performance aspects of a multitrigger based data analysis approach by using O(100s) long stretches of mock data in coincidence with the times of observed quasiperiodic oscillations, and by using the known sky location of the source. We analytically derive the probability density function of the background distribution and compare to the results obtained by applying the concept to simulated Gaussian noise, as well as off-source playground data collected by the 4-km Hanford detector during LIGO’s fifth science run (S5). We show that the transient glitch rejection and adaptive differential energy comparison methods we apply succeed in rejecting outliers in the fifth science run background data. Finally, we discuss how to extend the method to a network containing multiple detectors, and as an example, tune the method to maximize sensitivity to soft gamma repeater 1806-20 flare times.

  6. Discovery of SiO band emission from Galactic B[e] supergiants

    E-print Network

    Kraus, Michaela; Cidale, Lydia; Arias, Maria Laura; Torres, Andrea; Fernandes, Marcelo Borges

    2015-01-01

    B[e] supergiants (B[e]SGs) are evolved massive stars in a short-lived transition phase. During this phase, these objects eject large amounts of material, which accumulates in a circumstellar disk-like structure. The expelled material is typically dense and cool, providing the cradle for molecule and dust condensation and for a rich, ongoing chemistry. Very little is known about the chemical composition of these disks, beyond the emission from dust and CO revolving around the star on Keplerian orbits. As massive stars preserve an oxygen-rich surface composition throughout their life, other oxygen-based molecules can be expected to form. As SiO is the second most stable oxygen compound, we initiated an observing campaign to search for first-overtone SiO emission bands. We obtained high-resolution near-infrared L-band spectra for a sample of Galactic B[e]SGs with reported CO band emission. We clearly detect emission from the SiO first-overtone bands in CPD-52 9243 and indications for faint emission in HD 62623, ...

  7. Exponentially Modified Gaussian Function. An Empirical Equation for Description of the Band Emission of Inorganic Phosphors

    NASA Astrophysics Data System (ADS)

    Nötzold, D.

    1997-09-01

    The empirically found, exponentially modified Gaussian function is used for the description of the band emission of inorganic phosphors. The function includes the two parameters, the intensity of the maximum (I0) and its spectral position (-0), and besides two parameters for the slope of the flanks of the emission band (k1, k2) and two parameters for their deviation from the true Gaussian distribution (n1, n2). The equation is applied to the emission spectra of centre phosphors and crystal phosphors doped by different activator ions and moreover of non-activated phosphors. Correlation coefficients are in the order of magnitude of 0.9999. The function also succeeded in splitting up emission bands into two bands. Die empirisch gefundene Gleichung ist eine exponentiell modifizierte Gauss-Funktion. Sie dient zur Beschreibung der Emissionsspektren von anorganischen Leuchtstoffen mit bandenf<>oeh<>rmiger Emission. Die Funktion enthält neben den beiden Parametern Maximumsintensität (I0) und Maximumslage (-0) für jeden der beiden Kurven<>aeh<>ste jeweils einen Parameter für seine Neigung (k1, k2) und jeweils einen für seine Abweichung von der Gauss-Verteilung (n1, n2). Die Gleichung wird auf die Emissionsspektren von Zentren- und Kristallphosphoren mit unterschiedlichen Aktivatoren sowie von Reinstoffluminophoren angewendet. Die Korrelationskoeffizienten liegen im Bereich von 0,9999. Die Funktion wird auch bei Bandentrennungen mit Erfolg eingesetzt.

  8. Anatomy of the AGN in NGC 5548. V. A clear view of the X-ray narrow emission lines

    NASA Astrophysics Data System (ADS)

    Whewell, M.; Branduardi-Raymont, G.; Kaastra, J. S.; Mehdipour, M.; Steenbrugge, K. C.; Bianchi, S.; Behar, E.; Ebrero, J.; Cappi, M.; Costantini, E.; De Marco, B.; Di Gesu, L.; Kriss, G. A.; Paltani, S.; Peterson, B. M.; Petrucci, P.-O.; Pinto, C.; Ponti, G.

    2015-09-01

    Context. Our consortium performed an extensive multi-wavelength campaign of the nearby Seyfert 1 galaxy NGC 5548 in 2013-14. The source appeared unusually heavily absorbed in the soft X-rays, and signatures of outflowing absorption were also present in the UV. He-like triplets of neon, oxygen and nitrogen, and radiative recombination continuum (RRC) features were found to dominate the soft X-ray spectrum due to the low continuum flux. Aims: Here we focus on characterising these narrow emission features using data obtained from the XMM-Newton RGS (770 ks stacked spectrum). Methods: We use spex for our initial analysis of these features. Self-consistent photoionisation models from Cloudy are then compared with the data to characterise the physical conditions of the emitting region. Results: Outflow velocity discrepancies within the O VII triplet lines can be explained if the X-ray narrow-line region (NLR) in NGC 5548 is absorbed by at least one of the six warm absorber components found by previous analyses. The RRCs allow us to directly calculate a temperature of the emitting gas of a few eV (~104 K), favouring photoionised conditions. We fit the data with a Cloudy model of log ? = 1.45 ± 0.05 erg cm s-1, log NH = 22.9 ± 0.4 cm-2 and log vturb = 2.25 ± 0.5 km s-1 for the emitting gas; this is the first time the X-ray NLR gas in this source has been modelled so comprehensively. This allows us to estimate the distance from the central source to the illuminated face of the emitting clouds as 13.9 ± 0.6 pc, consistent with previous work.

  9. The size of the narrow-line-emitting region in the Seyfert 1 galaxy NGC 5548 from emission-line variability

    SciTech Connect

    Peterson, B. M.; Denney, K. D.; De Rosa, G.; Grier, C. J.; Pogge, R. W.; Kochanek, C. S.; Bentz, M. C.; Vestergaard, M.; Kilerci-Eser, E.; Dalla Bontà, E.; Ciroi, S.

    2013-12-20

    The narrow [O III] ??4959, 5007 emission-line fluxes in the spectrum of the well-studied Seyfert 1 galaxy NGC 5548 are shown to vary with time. From this we show that the narrow-line-emitting region has a radius of only 1-3 pc and is denser (n {sub e} ? 10{sup 5} cm{sup –3}) than previously supposed. The [O III] line width is consistent with virial motions at this radius given previous determinations of the black hole mass. Since the [O III] emission-line flux is usually assumed to be constant and is therefore used to calibrate spectroscopic monitoring data, the variability has ramifications for the long-term secular variations of continuum and emission-line fluxes, though it has no effect on shorter-term reverberation studies. We present corrected optical continuum and broad H? emission-line light curves for the period 1988-2008.

  10. The MAON model of Astronomical Unidentified Infrared Emission Bands

    NASA Astrophysics Data System (ADS)

    Kwok, Sun; Zhang, Yong

    2015-08-01

    Infrared spectroscopic observations of the stretching and bending modes of aliphatic and aromatic compounds are now seen throughout the Universe, from the diffuse interstellar medium of the Milky Way Galaxy to distant galaxies. Observations of evolved stars have revealed a rapid (~10$^3$ year time scale) and continuous synthesis of organic materials from the end of the asymptotic giant branch (AGB), to proto-planetary nebulae, to planetary nebulae. These synthesized products are ejected into the interstellar medium through stellar winds and as a result enriching the Galaxy with complex organics. Analysis of the infrared spectra suggests that the chemical structure of the carrier is consistent with that of mixed aromatic and aliphatic nanoparticles (MAON). These structures are very similar to those of the insoluble organic matter found in meteorites, suggesting that the early solar system may have been enriched by stellar ejecta.ReferencesKwok, S. The Synthesis of Organic and Inorganic Compounds in Evolved Stars, Nature, 430, 985 (2004)Kwok, S. and Zhang, Y. Mixed aromatic/aliphatic organic nanoparticles as carriers of unidentified infrared emission features, Nature, 479, 80 (2011)Kwok, S. Organic Matter in the Universe, Wiley (2011)

  11. Clicking in a Killer Whale Habitat: Narrow-Band, High-Frequency Biosonar Clicks of Harbour Porpoise (Phocoena phocoena) and Dall’s Porpoise (Phocoenoides dalli)

    PubMed Central

    Kyhn, Line A.; Tougaard, Jakob; Beedholm, Kristian; Jensen, Frants H.; Ashe, Erin; Williams, Rob; Madsen, Peter T.

    2013-01-01

    Odontocetes produce a range of different echolocation clicks but four groups in different families have converged on producing the same stereotyped narrow band high frequency (NBHF) click. In microchiropteran bats, sympatric species have evolved the use of different acoustic niches and subtly different echolocation signals to avoid competition among species. In this study, we examined whether similar adaptations are at play among sympatric porpoise species that use NBHF echolocation clicks. We used a six-element hydrophone array to record harbour and Dall’s porpoises in British Columbia (BC), Canada, and harbour porpoises in Denmark. The click source properties of all porpoise groups were remarkably similar and had an average directivity index of 25 dB. Yet there was a small, but consistent and significant 4 kHz difference in centroid frequency between sympatric Dall’s (137±3 kHz) and Canadian harbour porpoises (141±2 kHz). Danish harbour porpoise clicks (136±3 kHz) were more similar to Dall’s porpoise than to their conspecifics in Canada. We suggest that the spectral differences in echolocation clicks between the sympatric porpoises are consistent with evolution of a prezygotic isolating barrier (i.e., character displacement) to avoid hybridization of sympatric species. In practical terms, these spectral differences have immediate application to passive acoustic monitoring. PMID:23723996

  12. A Randomized Controlled Clinical Study Comparing the Diagnostic Accuracy of the Histologic Prediction for Colorectal Polyps Depending on the Use of Either Magnified or Nonmagnified Narrow Band Imaging

    PubMed Central

    Kim, Jin Joo; Hong, Kyoung Sup; Kim, Joo Sung; Jung, Hyun Chae

    2015-01-01

    Background/Aims: The aim of this study was to compare the diagnostic capabilities of narrow band imaging (NBI) colonoscopy with and without optical magnification in differentiating neoplastic from nonneoplastic colorectal polyps. Methods: Between April 2012 and March 2013, 122 patients with colorectal polyps detected by using diagnostic conventional colonoscopy were prospectively enrolled. A total of 236 polyps were evaluated with NBI, in vivo in real time during therapeutic colonoscopy, by one experienced endoscopist. Whether magnification was used or not was determined by randomization. After an in vivo real-time endoscopic prediction of histology, all lesions were endoscopically excised. Surgical pathologic reports were used as the criterion standards. The sensitivity (Sn), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of identifying neoplastic polyps were calculated. Results: A total of 236 lesions with an average size of 5.6 mm in 122 patients were assessed (159 neoplastic, 77 nonneoplastic). The Sn, Sp, PPV, and NPV in differentiating neoplastic from nonneoplastic lesions with the magnified NBI were 97.5%, 83.3%, 94.0%, and 92.6%, respectively, whereas those of the nonmagnified NBI group were 97.5%, 85.1%, 91.7%, and 95.2%, respectively. Conclusions: Nonmagnified NBI colonoscopy distinguishes neoplastic from nonneoplastic colorectal polyps as accurately as does magnified NBI colonoscopy. PMID:26668800

  13. Absorption of monochromatic and narrow band radiation in the visible and near IR by both mitochondrial and non-mitochondrial photoacceptors results in photobiomodulation.

    PubMed

    Passarella, Salvatore; Karu, Tiina

    2014-11-01

    In addition to the major functions performed by in the cell, mitochondria play a major role in cell-light interaction. Accordingly it is generally accepted that mitochondria are crucial in cell photobiomodulation; however a variety of biomolecules themselves proved to be targets of light irradiation. We describe whether and how mitochondria can interact with monochromatic and narrow band radiation in the red and near IR optical regions with dissection of both structural and functional effects likely leading to photobiostimulation. Moreover we also report that a variety of biomolecules localized in mitochondria and/or in other cell compartments including cytochrome c oxidase, some proteins, nucleic acids and adenine nucleotides are light sensitive with major modifications in their biochemistry. All together the reported investigations show that the elucidation of the mechanism of the light interaction with biological targets still remains to be completed, this needing further research, however the light sensitivity of a variety of molecules strongly suggests that photobiomodulation could be used in both in photomedicine and in biotechnology. PMID:25226343

  14. Narrow-Band Imaging Magnifying Endoscopy versus Lugol Chromoendoscopy with Pink-Color Sign Assessment in the Diagnosis of Superficial Esophageal Squamous Neoplasms: A Randomised Noninferiority Trial

    PubMed Central

    Goda, Kenichi; Dobashi, Akira; Yoshimura, Noboru; Kato, Masayuki; Aihara, Hiroyuki; Sumiyama, Kazuki; Toyoizumi, Hirobumi; Kato, Tomohiro; Ikegami, Masahiro; Tajiri, Hisao

    2015-01-01

    Previous studies have shown the high diagnostic accuracy of narrow-band imaging magnifying endoscopy (NBI-ME) and Lugol chromoendoscopy with pink-color sign assessment (LCE-PS) for superficial esophageal squamous cell carcinoma (SESCC). However, there has been no controlled trial comparing these two diagnostic techniques. We conducted a randomized noninferiority trial to compare the diagnostic accuracy of NBI-ME and LCE-PS. We recruited patients with, or with a history of, squamous cell carcinoma in the head and neck region or in the esophagus. They were randomly assigned to either NBI-ME or LCE-PS. When lesions > 5?mm in diameter were found as brownish areas on NBI or as Lugol-voiding lesions (LVL), they were evaluated to determine whether they are SESCC on the basis of the findings of NBI-ME or PS in the LVL. NBI-ME and LCE-PS were completed in 147 patients each. There was no significant difference in all diagnostic values between the two techniques. Compared with LCE-PS, NBI-ME showed a significantly shorter examination time but a larger number of misdiagnosed lesions especially in patients with many irregularly shaped multiform LVLs. Compared with LCE-PS, NBI-ME might be similarly accurate and less invasive, but less reliable in patients with many LVLs, in the diagnosis of SESCC. PMID:26229530

  15. Clicking in a killer whale habitat: narrow-band, high-frequency biosonar clicks of harbour porpoise (Phocoena phocoena) and Dall's porpoise (Phocoenoides dalli).

    PubMed

    Kyhn, Line A; Tougaard, Jakob; Beedholm, Kristian; Jensen, Frants H; Ashe, Erin; Williams, Rob; Madsen, Peter T

    2013-01-01

    Odontocetes produce a range of different echolocation clicks but four groups in different families have converged on producing the same stereotyped narrow band high frequency (NBHF) click. In microchiropteran bats, sympatric species have evolved the use of different acoustic niches and subtly different echolocation signals to avoid competition among species. In this study, we examined whether similar adaptations are at play among sympatric porpoise species that use NBHF echolocation clicks. We used a six-element hydrophone array to record harbour and Dall's porpoises in British Columbia (BC), Canada, and harbour porpoises in Denmark. The click source properties of all porpoise groups were remarkably similar and had an average directivity index of 25 dB. Yet there was a small, but consistent and significant 4 kHz difference in centroid frequency between sympatric Dall's (137±3 kHz) and Canadian harbour porpoises (141±2 kHz). Danish harbour porpoise clicks (136±3 kHz) were more similar to Dall's porpoise than to their conspecifics in Canada. We suggest that the spectral differences in echolocation clicks between the sympatric porpoises are consistent with evolution of a prezygotic isolating barrier (i.e., character displacement) to avoid hybridization of sympatric species. In practical terms, these spectral differences have immediate application to passive acoustic monitoring. PMID:23723996

  16. RFID Transponders' Radio Frequency Emissions in Aircraft Communication and Navigation Radio Bands

    NASA Technical Reports Server (NTRS)

    Nguyen, Truong X.; Ely, Jay J.; Williams, Reuben A.; Koppen, Sandra V.; Salud, Maria Theresa P.

    2006-01-01

    Radiated emissions in aircraft communication and navigation bands are measured from several active radio frequency identification (RFID) tags. The individual tags are different in design and operations. They may also operate in different frequency bands. The process for measuring the emissions is discussed, and includes tag interrogation, reverberation chamber testing, and instrument settings selection. The measurement results are described and compared against aircraft emission limits. In addition, interference path loss for the cargo bays of passenger aircraft is measured. Cargo bay path loss is more appropriate for RFID tags than passenger cabin path loss. The path loss data are reported for several aircraft radio systems on a Boeing 747 and an Airbus A320.

  17. An Unusual Rotationally Modulated Attenuation Band in the Jovian Hectometric Radio Emission Spectrum

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Kurth, W. S.; Menietti, J. D.; Persoon, A. M.

    1998-01-01

    A well-defined attenuation band modulated by the rotation of Jupiter has been found in the spectrum of Jovian hectometric radiation using data from the Galileo plasma wave instrument. The center frequency of this band usually occurs in the frequency range from about 1 to 3 MHz and the bandwidth is about 10 to 20 percent. The center frequency varies systematically with the rotation of Jupiter and has two peaks per rotation, the first at a system III longitude of about 50 deg, and the second at about 185 deg. It is now believed that the attenuation occurs as the ray path from a high-latitude cyclotron maser source passes approximately parallel to the magnetic field near the northern or southern edges of the Io L-shell. The peak at 50 deg system 3 longitude is attributed to radiation from a southern hemisphere source and the peak at 185 deg is from a northern hemisphere source. The attenuation is thought to be caused by coherent scattering or shallow angle reflection from field-aligned density irregularities near the Io L-shell. The narrow bandwidth indicates that the density irregularities are confined to a very narrow range of L values (Delta L = 0.2 to 0.4) near the Io L-shell.

  18. GROUND-BASED DETECTIONS OF THERMAL EMISSION FROM THE DENSE HOT JUPITER WASP-43b IN THE H AND K{sub s} BANDS

    SciTech Connect

    Wang, W.; Zhao, G.; Van Boekel, R.; Henning, Th.; Madhusudhan, N.; Chen, G.

    2013-06-10

    We report new detections of thermal emission from the transiting hot Jupiter WASP-43b in the H and K{sub s} bands as observed at secondary eclipses. The observations were made with the WIRCam instrument on the Canada-France-Hawaii Telescope. We obtained a secondary eclipse depth of 0.103{sub -0.017}{sup +0.017}%$ and 0.194{sub -0.029}{sup +0.029} in the H and K{sub s} bands, respectively. The K{sub s}-band depth is consistent with the previous measurement in the narrow band centered at 2.09 {mu}m by Gillon et al. Our eclipse depths in both bands are consistent with a blackbody spectrum with a temperature of {approx}1850 K, slightly higher than the dayside equilibrium temperature without day-night energy redistribution. Based on theoretical models of the dayside atmosphere of WASP-43b, our data constrain the day-night energy redistribution in the planet to be {approx}< 15%-25%, depending on the metal content in the atmosphere. Combined with energy balance arguments, our data suggest that a strong temperature inversion is unlikely in the dayside atmosphere of WASP-43b. However, a weak inversion cannot be strictly ruled out at the current time. Future observations are required to place detailed constraints on the chemical composition of the atmosphere.

  19. Polycyclic aromatic hydrocarbons and the unidentified infrared emission bands - Auto exhaust along the Milky Way

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Tielens, A. G. G. M.; Barker, J. R.

    1985-01-01

    The unidentified infrared emission features (UIR bands) are attributed to a collection of partially hydrogenated, positively charged polycyclic aromatic hydrocarbons (PAHs). This assignment is based on a spectroscopic analysis of the UIR bands. Comparison of the observed interstellar 6.2 and 7.7-micron bands with the laboratory measured Raman spectrum of a collection of carbon-based particulates (auto exhaust) shows a very good agreement, supporting this identification. The infrared emission is due to relaxation from highly vibrationally and electronically excited states. The excitation is probably caused by UV photon absorption. The infrared fluorescence of one particular, highly vibrationally excited PAH (chrysene) is modeled. In this analysis the species is treated as a molecule rather than bulk material and the non-thermodynamic equilibrium nature of the emission is fully taken into account. From a comparison of the observed ratio of the 3.3 to 11.3-micron UIR bands with the model calculations, the average number of carbon atoms per molecule is estimated to be about 20. The abundance of interstellar PAHs is calculated to be about 2 x 10 to the -7th with respect to hydrogen.

  20. Dayglow emissions of the O2 Herzberg bands and the Rayleigh backscattered spectrum of the earth

    NASA Technical Reports Server (NTRS)

    Frederick, J. E.; Abrams, R. B.

    1982-01-01

    It is pointed out that numerous fluorescent emissions from the Herzberg bands of molecular oxygen lie in the spectral region 242-300 nm. This coincides with the wavelength range used by orbiting spectrometers that observe the Rayleigh backscattered spectrum of the earth for the purpose of monitoring the vertical distribution of stratospheric ozone. Model calculations suggest that Herzberg band emissions in the dayglow could provide significant contamination of the ozone measurements if the quenching rate of O2(A3Sigma) is sufficiently small. It is noted that this is especially true near 255 nm, where the most intense fluorescent emissions relative to the Rayleigh scattered signal are located and where past satellite measurements have shown a persistent excess radiance above that expected for a pure ozone absorbing and molecular scattering atmosphere. Very small quenching rates, however, are adequate to reduce the dayglow emission to negligible levels. Noting that available laboratory data have not definitely established the quenching on the rate of O2(A3Sigma) as a function of vibration level, it is emphasized that such information is required before the Herzberg band contributions can be evaluated with confidence.

  1. Effective optical identification of type “0-IIb” early gastric cancer with narrow band imaging magnification endoscopy, successfully treated by endoscopic submucosal dissection

    PubMed Central

    Eleftheriadis, Nikolas; Inoue, ?aruhiro; Ikeda, Haruo; Onimaru, Manabu; Yoshida, Akira; Maselli, Roberta; Santi, Grace; Hamatani, Shigeharu; Kudo, Shin-ei

    2015-01-01

    Background Endoscopic submucosal dissection (ESD) is currently considered the minimal invasive endoscopic treatment for early gastric cancer. Most superficial gastric neoplastic lesions are depressed type “0-IIc” (70-80%), while totally flat, classified as type “0-IIb” early gastric cancer, is rarely reported (0.4%). The aim of the present study was to assess the efficacy of narrow band imaging (NBI) magnification endoscopy in identifying type “0-IIb” early gastric cancer and ESD treatment with curative intention. Methods Twelve of 615 (2%) patients (10 males, median 72 years), treated by ESD at our center, were diagnosed as type “0-IIb” gastric cancer. Ten had exclusively type “0-IIb”, while two had combined types “0-IIb+IIc” and “0-IIa+IIb” gastric cancer. Initial diagnosis was made during screening gastroscopy, while NBI magnification endoscopy combined with indigo-carmine chromoendoscopy were also used. Results White light endoscopy showed only superficial redness. One patient with signet-ring carcinoma showed whitish appearance. Indigo-carmine chromoendoscopy showed better visualization, while NBI magnification endoscopy revealed abnormal mucosal microsurface and microvascular findings which enabled border marking. ESD with curative intention was completed without complications. Histological examination showed complete (R0) resection, in 10 patients (83%). One patient with positive margins received additional surgery (8%). Mean procedure time was 149 (range 60-190) min. One to six years post-ESD all patients remain alive. Conclusions ESD is considered a safe and effective curative treatment for type “0-IIb” gastric cancer, resulting in long-term disease-free survival. NBI magnification endoscopy is effective for accurate optical identification and border marking of type “0-IIb” early gastric cancer. PMID:25609014

  2. Diagnosis of small intramucosal signet ring cell carcinoma of the stomach by non-magnifying narrow-band imaging: A pilot study

    PubMed Central

    Watari, Jiro; Tomita, Toshihiko; Ikehara, Hisatomo; Taki, Masato; Ogawa, Tomohiro; Yamasaki, Takahisa; Kondo, Takashi; Toyoshima, Fumihiko; Sakurai, Jun; Kono, Tomoaki; Tozawa, Katsuyuki; Ohda, Yoshio; Oshima, Tadayuki; Fukui, Hirokazu; Hirota, Seiichi; Miwa, Hiroto

    2015-01-01

    AIM: To examine the efficacy of non-magnifying narrow-band imaging (NM-NBI) imaging for small signet ring cell carcinoma (SRC). METHODS: We retrospectively analyzed 14 consecutive small intramucosal SRCs that had been treated with endoscopic submucosal dissection (ESD) and 14 randomly selected whitish gastric ulcer scars (control). The strength and shape of the SRCs and whitish scars by NM-NBI and white-light imaging (WLI) were assessed with Image J (NIH, Bethesda). RESULTS: NM-NBI findings of SRC showed a clearly isolated whitish area amid the brown color of the surrounding normal mucosa. The NBI index, which indicates the potency of NBI for visualizing SRC, was significantly higher than the WLI index (P = 0.001), indicating SRC was more clearly identified by NM-NBI. Although the NBI index was not significantly different between SRCs and controls, the circle (C)-index, as an index of circularity of tumor shape, was significantly higher in SRCs (P = 0.001). According to the receiver-operating characteristic analysis, the resulting cut-off value of the circularity index (C-index) for SRC was 0.60 (85.7% sensitivity, 85.7% specificity). Thus a lesion with a C-index ? 0.6 was significantly more likely to be an SRC than a gastric ulcer scar (OR = 36.0; 95%CI: 4.33-299.09; P = 0.0009). CONCLUSION: Small isolated whitish round area by NM-NBI endoscopy is a useful finding of SRCs which is the indication for ESD. PMID:26380053

  3. Evaluation of the Efficacy of Topical Ethyl Vanillate in Enhancing the Effect of Narrow Band Ultraviolet B against Vitiligo: A Double Blind Randomized, Placebo-Controlled Clinical Trial

    PubMed Central

    Namazi, Mohammad Reza; Shotorbani, Amir Kalafi

    2015-01-01

    Background: Vitiligo is an acquired disease of skin that presents with depigmented patches due to lack of melanocytes in the epidermis. Accumulation of toxic free radicals like hydrogen peroxide in the epidermis may be responsible for melanocytes death. Since ethyl vanillate (vanillic acid ethyl ester) is a strong hydrogen peroxide scavenger, it may be effective against vitiligo. This study was carried out to evaluate the effect of ethyl vanillate cream on vitiligo patients receiving phototherapy. Methods: A double-blind placebo-controlled clinical trial using ethyl vanillate cream 20% was performed on 30 cases of generalized stable vitiligo (randomly selected) who were receiving phototherapy in the outpatient clinic of Faghihi Hospital (Shiraz, Iran). The patients randomly applied ethyl vanillate on an assigned lesion (left or right side of the body) and placebo on the opposite side lesion (almost the same size and location) twice a day for 3 months, while receiving a narrow band ultraviolet B (NB-UVB) 2-3 times weekly. Photos were taken at the beginning of the trial and at the end of 4th, 8th, and 12th weeks. Then, images were compared with the photos from the beginning of the trial based on VASI score. Results: There was a significant change in pigmentation after applying ethyl vanillate compared with baseline in medication side (P=0.002), but no significant change in placebo side (P=0.066). Additionally, there was a significant difference between medication and placebo sides in pigmentation (P=0.005). Conclusion: Ethyl vanillate may serve as an adjunct therapy for the treatment of vitiligo, although changes in pigmentation are mild clinically. PMID:26538775

  4. Nitric oxide delta band emission in the earth's atmosphere - Comparison of a measurement and a theory

    NASA Technical Reports Server (NTRS)

    Rusch, D. W.; Sharp, W. E.

    1981-01-01

    Attention is given to the altitude dependent emission rate in the delta-bands of nitric oxide as measured in the earth's atmosphere at night by a scanning ultraviolet spectrometer. It is noted that the reaction responsible is the two-body association of nitrogen and oxygen atoms. The measurements show a vertical intensity beneath the layer for the delta-band system of 19 R. The horizontal emission rate is found to increase from 70 R at 117 km to 140 R at 150 km. The data are analyzed with a one-dimensional, time-dependent, vertical-transport model of odd nitrogen photochemistry. The calculated and measured intensities agree so long as the quenching of N(2D) by atomic oxygen is near 5 x 10 to the -13 cu cm/sec.

  5. L to X-band scatter and emission measurements of vegetation

    NASA Astrophysics Data System (ADS)

    Hueppi, R.; Schanda, E.

    1986-08-01

    A broad-band H and V polarization radiometer was combined with a noise transmitter to an instrument for measuring active and passive microwave signatures at seven frequencies between L and X band. This radiometer-scatterometer is operated from a cherry picker over agricultural fields. During the growing seasons the development of sugar-beet, wheat, and corn was measured. The geometrical structure of the vegetation cover was described by recording the crop type, the distances between the plants, and the canopy height. The soil underneath was characterized by moisture, temperature profile, and dielectric constant. Another variable was the seasonal change in water content of the plants. Relating these parameters to the microwave signatures reveals the interaction of scatter and emission processes between soil and vegetation. Significant differences of the emission and scattering behavior for the measured crops are found.

  6. Anomalous Series of Bands in the Edge Emission Spectra of CdS(?)

    NASA Astrophysics Data System (ADS)

    Morozova, N. K.; Kanakhin, A. A.; Galstyan, V. G.; Shnitnikov, A. S.

    2015-02-01

    The region of the edge emission spectrum of CdS(O) single crystals with cadmium excess is examined. An anomalous series of equidistant bands with leading line at 514 nm and phonon replicas has been revealed. These bands grow in intensity with increase of the excitation density up to 1026-1027 cm-3?s-1 at 80 K, and the leading line of the series is observed even at 300 K. It is shown that luminescence is conditioned by the exciton spectrum in perfect bulk single-crystals of CdO. Some characteristics of this spectrum are presented, in particular, the dependence on temperature, excitation intensity, composition and size of the crystals, and the LO interaction. The results experimentally confirm the theoretically calculated magnitude of the direct band gap of CdO.

  7. Strong Band-Edge Emission from ZnS Quantum Dots Stabilized by Gum Arabic

    NASA Astrophysics Data System (ADS)

    Hatim, Dirar Mohamed El-Khair

    2008-12-01

    ZnS quantum dots (QDs), prepared by soft-condensation, exhibit robust structure of a quantum size equal 3.13 nm mediated two-dimensional gum Arabic surfactant as characterized by scan tunnelling microscope (STM). Strong blue-shifted absorption and emission bands are depicted by optical characterization even for the sample stored under ambient condition for two weeks. These enhancements can be attributed to the completely passivated surface trap states by Gum Arabic.

  8. Excitation temperatures determined from H{sup +}{sub 3} hot band emission in the Jovian ionosphere

    SciTech Connect

    Jagod, M.F.; Oka, T.; Geballe, T.R.

    1996-12-31

    Since the observation of the 3.544 {mu}m 2v{sup 0}{sub 2} {r_arrow} v{sub 2} (J = 9, K = 9 {r_arrow} J = 8, G = 9, U = 1) hot band transition of H{sup +}{sub 3} in the polar regions of Jupiter, the authors have pursued the simultaneous detection of additional hot band transitions with fundamental band transitions in order to derive well determined H+ excitation temperatures. The authors report 9 additional resolved 2{nu}{sub 2}{sup 2} {r_arrow} {nu}{sub 2} and {nu}{sub 1} + {nu}{sub 2} {r_arrow} {nu}{sub 1} hot band transitions observed in emission at 3.52, 3.63, 3.66, and 3.84 {mu}m. The hot band transitions have thus far only been detected in the polar regions, with the occasional exception being the 3.544 {mu}m 2{nu}{sup 0}{sub 2} {r_arrow} {nu}{sub 2} transition around 45{degrees}S latitude during the 1994 Comet Shoemaker Levy-9 encounter. Temporal and spatial variation of the excitation temperatures as well as their dependence on vibrational mode will be presented. Anomalous line intensities, e.g. {sup r}R(3,3){sup -b} will also be discussed. All observations were made with the CGS4 spectrometer at the United Kingdom Infrared Telescope on Mauna Kea, Hawaii.

  9. Rain effect on Aquarius L-band Emissivity and Backscatter Model Functions

    NASA Astrophysics Data System (ADS)

    Tang, W.; Yueh, S. H.; Fore, A.; Neumann, G.; Hayashi, A.

    2012-12-01

    Remote sensing of sea surface salinity (SSS) is being performed by Aquarius and SMOS missions, which are using L-band radiometry to sense the microwave emissions from sea surfaces. To enable accurate SSS retrieval, it is essential to correct the impact of sea surface roughness on L-band brightness temperatures. In addition, the impact of rain has to be carefully assessed and accounted for. Although the atmospheric attenuation caused by raindrops are likely negligible at 1.4GHz, other factors must be considered because they may have indirect but important contribution to the surface roughness and consequently L-band brightness temperatures. For example, the wind speed dependent roughness correction will be corrupted when rain striking the water, creating rings, stalks, and crowns from which the signal scatters. It is also unknown how long the freshwater stays at surface while through the oceanic mixing process at various regions over global oceans. We collocated the Aquarius L-band data with various wind products, including SSM/I, NCEP, ASCAT and WindSAT, as well as the SSM/I and WindSAT rain products. During the first four months of Aquarius mission, near 1.9 million pixels are identified under rain conditions by either SSM/I or WindSAT. We derived the L-band emissivity and backscatter geophysical model functions (GMF), parameterized by SSM/I and NCEP winds for rain-free conditions. However, the residual ocean surface emissivity (the Aquarius measured minus the rain-free model predictions) reveals profound resemblance with global precipitation pattern. In region dominated by rain, e.g. ITCZ, northern hemisphere storm track, and Indian Ocean partially under the influence of summer monsoon, the GMF built using rain free data underestimates excess emissivity about 0.5 to 1 K. The dependence of residual of emissivity and backscatter is shown as a function of wind speed and rain rate. A modified GMF is developed including rain rate as one of the parameters. Due to limited samples at heavy rain, we binned the data in four rain domains: rain free, light (0-2 mm/hr), moderate (2-5 mm/hr) and heavy (>5 mm/hr). Comparing the modeling coefficients with rain free GMF, the major changes introduced by rain is found to occur at low to medium wind speeds, and curves for different rain domains converge for high wind (beyond 15 m/s).

  10. Origin of the low-energy emission band in epitaxially grown para-sexiphenyl nanocrystallites

    SciTech Connect

    Kadashchuk, A.; Schols, S.; Heremans, P.; Skryshevski, Yu.; Piryatinski, Yu.; Beinik, I.; Teichert, C.; Hernandez-Sosa, G.; Sitter, H.; Andreev, A.; Frank, P.; Winkler, A.

    2009-02-28

    A comparative study of steady-state and time-resolved photoluminescence of para-sexiphenyl (PSP) films grown by organic molecular beam epitaxy (OMBE) and hot wall epitaxy (HWE) under comparable conditions is presented. Using different template substrates [mica(001) and KCl(001) surfaces] as well as different OMBE growth conditions has enabled us to vary greatly the morphology of the PSP crystallites while keeping their chemical structure virtually untouched. We prove that the broad redshifted emission band has a structure-related origin rather than being due to monomolecular oxidative defects. We conclude that the growth conditions and type of template substrate impacts substantially on the film morphology (measured by atomic force microscopy) and emission properties of the PSP films. The relative intensity of the defect emission band observed in the delayed spectra was found to correlate with the structural quality of PSP crystallites. In particular, the defect emission has been found to be drastically suppressed when (i) a KCl template substrate was used instead of mica in HWE-grown films, and (ii) in the OMBE-grown films dominated by growth mounds composed of upright standing molecules as opposed to the films consisting of crystallites formed by molecules lying parallel to the substrate.

  11. Multiyear On-orbit Calibration and Performance of Terra MODIS Thermal Emissive Bands

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Chiang, Kwo-Fu; Wu, Aisheng; Barnes, William; Guenther, Bruce; Salomonson, Vincent

    2007-01-01

    Since launch in December 1999, Terra MODIS has been making continuous Earth observations for more than seven years. It has produced a broad range of land, ocean, and atmospheric science data products for improvements in studies of global climate and environmental change. Among its 36 spectral bands, there are 20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB). MODIS thermal emissive bands cover the mid-wave infrared (MWIR) and long-wave infrared (LWIR) spectral regions with wavelengths from 3.7 to 14.4pm. They are calibrated on-orbit using an on-board blackbody (BB) with its temperature measured by a set of thermistors on a scan-by-scan basis. This paper will provide a brief overview of MODIS TEB calibration and characterization methodologies and illustrate on-board BB functions and TEB performance over more than seven years of on-orbit operation and calibration. Discussions will be focused on TEB detector short-term stability and noise characterization, and changes in long-term response (or system gain). Results show that Terra MODIS BB operation has been extremely stable since launch. When operated at its nominal controlled temperature of 290K, the BB temperature variation is typically less than +0.30mK on a scan-by-scan basis and there has been no time-dependent temperature drift. In addition to excellent short-term stability, most TEB detectors continue to meet or exceed their specified noise characterization requirements, thus enabling calibration accuracy and science data product quality to be maintained. Excluding the noisy detectors identified pre-launch and those that occurred post-launch, the changes in TEB responses have been less than 0.7% on an annual basis. The optical leak corrections applied to bands 32-36 have been effective and stable over the entire mission

  12. The microwave emission and transmission characters of deciduous forest at L-band

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongjun; Yuan, Yu; Zheng, Xingming; Zhu, Xiaoming; Fu, Xiuli

    2014-11-01

    Forest covers about 30% of earth surface, which plays an important role in global forecast and carbon cycle. Monitoring forest biomass, and retrieving soil moisture at forest area, are the main goals of most passive microwave sensors on satellite missions. L-band is the most sensitive frequency among all the frequencies due to its good penetration ability. Because of its variety of the size of scattering components, the complicated structures and species of forest, it is difficult to describe the scattering and attenuation characters of forest in modeling microwave emission at forest area. In this paper, we studied the emissivity and transmissivity of deciduous forest at L(1.4GHz) by model simulation and field experiment. The microwave emission model was based on Matrix-Doubling algorithm. The comparison between simulated emissivity and measured data collected during an experiment at Maryland, USA in 2007 was good. Since theoretical model like Matrix-Doubling is too complicated to be used in retrial application, we mapped the results of Matrix-Doubling to a simple 0th-order model, also called ?-? model, by setting the simulated emissivity to be the emissivity of 0th-order model at the same environment, which 2 unknown variables---opacity ? and effective single scattering albedo ? need to be determined. To valited ? (transmissivity of forest) simulated by Matrix-Doubling, we took an deciduous forest experiment by an L band microwave radiometer under trees at JingYueTan area, Changchun, Jilin Province in April to June in 2014. Thus the ? of forest can be determined. The matching results are presented in this paper. The relationship between LAI and forest microwave characters are discussed.

  13. A large narrow-band H? survey at z˜ 0.2: the bright end of the luminosity function, cosmic variance and clustering across cosmic time

    NASA Astrophysics Data System (ADS)

    Stroe, Andra; Sobral, David

    2015-10-01

    We have carried out the largest (>3.5 × 105 Mpc3, 26 deg2) H? narrow-band survey to date at z ˜ 0.2 in the SA22, W2 and XMMLSS extragalactic fields. Our survey covers a large enough volume to overcome cosmic variance and to sample bright and rare H? emitters up to an observed luminosity of ˜1042.4 erg s-1, equivalent to ˜11 M? yr-1. Using our sample of 220 sources brighter than >1041.4 erg s-1 (>1 M? yr-1), we derive H? luminosity functions, which are well described by a Schechter function with ?? = 10-2.85 ± 0.03 Mpc-3 and L^*_H? = 10^{41.71± 0.02} erg s-1 (with a fixed faint end slope ? = -1.35). We find that surveys probing smaller volumes (˜3 × 104 Mpc3) are heavily affected by cosmic variance, which can lead to errors of over 100 per cent in the characteristic density and luminosity of the H? luminosity function. We derive a star formation rate density of ?SFRD = 0.0094 ± 0.0008 M? yr-1, in agreement with the redshift-dependent H? parametrization from Sobral et al. The two-point correlation function is described by a single power law ?(?) = (0.159 ± 0.012)?(-0.75 ± 0.05), corresponding to a clustering length of r0 = 3.3 ± 0.8 Mpc h-1. We find that the most luminous H? emitters at z ˜ 0.2 are more strongly clustered than the relatively fainter ones. The L^*_H? H? emitters at z ˜ 0.2 in our sample reside in ˜1012.5-13.5 M? dark matter haloes. This implies that the most star-forming galaxies always reside in relatively massive haloes or group-like environments and that the typical host halo mass of star-forming galaxies is independent of redshift if scaled by L_H? /L^*_H? (z), as proposed by Sobral et al.

  14. EXAMINING THE BROADBAND EMISSION SPECTRUM OF WASP-19b: A NEW z-BAND ECLIPSE DETECTION

    SciTech Connect

    Zhou, George; Bayliss, Daniel D. R.; Kedziora-Chudczer, Lucyna; Bailey, Jeremy

    2013-09-10

    WASP-19b is one of the most irradiated hot-Jupiters known. Its secondary eclipse is the deepest of all transiting planets and has been measured in multiple optical and infrared bands. We obtained a z-band eclipse observation with a measured depth of 0.080% {+-} 0.029%, using the 2 m Faulkes Telescope South, which is consistent with the results of previous observations. We combined our measurement of the z-band eclipse with previous observations to explore atmosphere models of WASP-19b that are consistent with its broadband spectrum. We use the VSTAR radiative transfer code to examine the effect of varying pressure-temperature profiles and C/O abundance ratios on the emission spectrum of the planet. We find that models with super-solar carbon enrichment best match the observations, which is consistent with previous model retrieval studies. We also include upper atmosphere haze as another dimension in the interpretation of exoplanet emission spectra and find that particles <0.5 {mu}m in size are unlikely to be present in WASP-19b.

  15. Monitoring water stress and fruit quality in an orange orchard under regulated deficit irrigation using narrow-band structural and physiological remote sensing indices

    NASA Astrophysics Data System (ADS)

    Stagakis, S.; González-Dugo, V.; Cid, P.; Guillén-Climent, M. L.; Zarco-Tejada, P. J.

    2012-07-01

    This paper deals with the monitoring of water status and the assessment of the effect of stress on citrus fruit quality using structural and physiological remote sensing indices. Four flights were conducted over a citrus orchard in 2009 using an unmanned aerial vehicle (UAV) carrying a multispectral camera with six narrow spectral bands in the visible and near infrared. Physiological indices such as the Photochemical Reflectance Index (PRI570), a new structurally robust PRI formulation that uses the 515 nm as the reference band (PRI515), and a chlorophyll ratio (R700/R670) were compared against the Normalized Difference Vegetation Index (NDVI), Renormalized Difference Vegetation Index (RDVI) and Modified Triangular Vegetation Index (MTVI) canopy structural indices for their performance in tracking water status and the effects of sustained water stress on fruit quality at harvest. The irrigation setup in the commercial orchard was compared against a treatment scheduled to satisfy full requirements (based on estimated crop evapotranspiration) using two regulated deficit irrigation (RDI) strategies. The water status of the trees throughout the experiment was monitored with frequent field measurements of stem water potential (?x), while titratable acidity (TA) and total soluble solids (TSS) were measured at harvest on selected trees from each irrigation treatment. The high spatial resolution of the multispectral imagery (30 cm pixel size) enabled identification of pure tree crown components, extracting the tree reflectance from shaded, sunlit and aggregated pixels. The physiological and structural indices were then calculated from each tree at the following levels: (i) pure sunlit tree crown, (ii) entire crown, aggregating the within-crown shadows, and (iii) simulating a lower resolution pixel, including tree crown, sunlit and shaded soil pixels. The resulting analysis demonstrated that both PRI formulations were able to track water status, except when water stress altered canopy structure. In such cases, PRI570 was more affected than PRI515 by the structural changes caused by sustained water stress throughout the season. Both PRI formulations were proven to serve as pre-visual water stress indicators linked to fruit quality TSS and TA parameters (r2 = 0.69 for PRI515 vs TSS; r2 = 0.58 vs TA). In contrast, the chlorophyll (R700/R670) and structural indices (NDVI, RDVI, MTVI) showed poor relationships with fruit quality and water status levels (r2 = 0.04 for NDVI vs TSS; r2 = 0.19 vs TA). The two PRI formulations showed strong relationships with the field-measured fruit quality parameters in September, the beginning of stage III, which appeared to be the period most sensitive to water stress and the most critical for assessing fruit quality in citrus. Both PRI515 and PRI570 showed similar performance for the two scales assessed (sunlit crown and entire crown), demonstrating that within-crown component separation is not needed in citrus tree crowns where the shaded vegetation component is small. However, the simulation conducted through spatial resampling on tree + soil aggregated pixels revealed that the physiological indices were highly affected by soil reflectance and between-tree shadows, showing that for TSS vs PRI515 the relationship dropped from r2 = 0.69 to r2 = 0.38 when aggregating soil + crown components. This work confirms a previous study that demonstrated the link between PRI570, water stress, and fruit quality, while also making progress in assessing the new PRI formulation (PRI515), the within-crown shadow effects on the physiological indices, and the need for high resolution imagery to target individual tree crowns for the purpose of evaluating the effects of water stress on fruit quality in citrus.

  16. Reduced threshold of optically pumped amplified spontaneous emission and narrow line-width electroluminescence at cutoff wavelength from bilayer organic waveguide devices.

    PubMed

    Chang, Jui-Fen; Huang, Yu-Syuan; Chen, Po-Ting; Kao, Ruei-Lin; Lai, Xuan-You; Chen, Chii-Chang; Lee, Cheng-Chung

    2015-06-01

    We present a detailed study of the optically and electrically pumped emission in the BSB-Cz/PVK bilayer waveguide devices. By optical pumping we demonstrate that PVK as a spacer between fluorescent BSB-Cz and ITO electrode allows the significant reduction of the threshold for amplified spontaneous emission (ASE) of BSB-Cz. The simulation provides a better understanding of how the PVK thickness affects the waveguide mode field distribution and hence the ASE threshold of BSB-Cz. On the other hand, the BSB-Cz/PVK bilayer OLED exhibits the external quantum efficiency of >1% and anisotropic electroluminescence with spectrally narrowed edge emission at the cutoff wavelength controlled by the BSB-Cz thickness. When tuning the cutoff wavelength to match the peak gain of BSB-Cz, we demonstrate an intense, particularly narrow edge emission (~5 nm) without obvious degradation of efficiency at a high current density of 1000 mA/cm2, suggesting a reliable device performance for high-power applications and further exploration of electrically-pumped ASE. PMID:26072828

  17. Probing the Ionization States of Polycyclic Aromatic Hydrocarbons via the 15-20 {\\mu}m Emission Bands

    E-print Network

    Shannon, M J; Peeters, E

    2015-01-01

    We report new correlations between ratios of band intensities of the 15-20 {\\mu}m emission bands of polycyclic aromatic hydrocarbons (PAHs) in a sample of fifty-seven sources observed with Spitzer/IRS. This sample includes Large Magellanic Cloud point sources from the SAGE-Spec survey, nearby galaxies from the SINGS survey, two Galactic ISM cirrus sources and the spectral maps of the Galactic reflection nebulae NGC 2023 and NGC 7023. We find that the 16.4, 17.4 and 17.8 {\\mu}m band intensities are inter-correlated in all environments. In NGC 2023 and NGC 7023 these bands also correlate with the 11.0 and 12.7 {\\mu}m band intensities. The 15.8 {\\mu}m band correlates only with the 15-20 {\\mu}m plateau and the 11.2 {\\mu}m emission. We examine the spatial morphology of these bands and introduce radial cuts. We find that these bands can be spatially organized into three sets: the 12.7, 16.4 and 17.8 {\\mu}m bands; the 11.2, 15.8 {\\mu}m bands and the 15-18 {\\mu}m plateau; and the 11.0 and 17.4 {\\mu}m bands. We also f...

  18. Ocean Surface Emissivity at L-band (1.4 GHz): The Dependence on Salinity and Roughness

    NASA Astrophysics Data System (ADS)

    Le Vine, D. M.; Lang, R. H.; Wentz, F. J.; Meissner, T.

    2012-12-01

    A characterization of the emissivity of sea water at L-band is important for the remote sensing of sea surface salinity. Measurements of salinity are currently being made in the radio astronomy band at 1.413 GHz by ESA's Soil Moisture and Ocean Salinity (SMOS) mission and NASA's Aquarius instrument aboard the Aquarius/SAC-D observatory. The goal of both missions is accuracy on the order of 0.2 psu. This requires accurate knowledge of the dielectric constant of sea water as a function of salinity and temperature and also the effect of waves (roughness). The former determines the emissivity of an ideal (i.e. flat) surface and the later is the major source of error from predictions based on a flat surface. These two aspects of the problem of characterizing the emissivity are being addressed in the context of the Aquarius mission. First, laboratory measurements are being made of the dielectric constant of sea water. This is being done at the George Washington University using a resonant cavity. In this technique, sea water of known salinity and temperature is fed into the cavity along its axis through a narrow tube. The sea water changes the resonant frequency and Q of the cavity which, if the sample is small enough, can be related to the dielectric constant of the sample. An extensive set of measurements have been conducted at 1.413 GHz to develop a model for the real and imaginary part of the dielectric constant as a function of salinity and temperature. The results are compared to the predictions of models based on parameterization of the Debye resonance of the water molecule. The models and measurements are close; however, the differences are significant for remote sensing of salinity. This is especially true at low temperatures where the sensitivity to salinity is lowest. Second, observations from Aquarius are being used to develop a model for the effect of wind-driven roughness (waves) on the emissivity in the open ocean. This is done by comparing the measured radiometric brightness temperature with the value expected for a surface with the same salinity and physical temperature. A parametric model for the excess brightness temperature as a function of wind speed and wind direction is developed in the form: ?TB = A0(w) + A1(w) cos(?) + A2(w) cos(2?) where w = wind speed; ? = wind direction (relative to the look direction of the radiometer) and ?TB = ?E Ts where Ts is the physical temperature and ?E is the change in emissivity caused by the waves. A0(w) is roughly linear with wind speed with values on the order of 3 K at 15 m/s. The directional dependence is much smaller but the data definitely indicate a directional component for wind speeds greater than 10-15 m/s. The coefficients depend on the incidence angle of the radiometer.

  19. Band-limited Green's Functions for Quantitative Evaluation of Acoustic Emission Using the Finite Element Method

    NASA Technical Reports Server (NTRS)

    Leser, William P.; Yuan, Fuh-Gwo; Leser, William P.

    2013-01-01

    A method of numerically estimating dynamic Green's functions using the finite element method is proposed. These Green's functions are accurate in a limited frequency range dependent on the mesh size used to generate them. This range can often match or exceed the frequency sensitivity of the traditional acoustic emission sensors. An algorithm is also developed to characterize an acoustic emission source by obtaining information about its strength and temporal dependence. This information can then be used to reproduce the source in a finite element model for further analysis. Numerical examples are presented that demonstrate the ability of the band-limited Green's functions approach to determine the moment tensor coefficients of several reference signals to within seven percent, as well as accurately reproduce the source-time function.

  20. Detection of a protostellar region, in BHR 71, revealed by the IR emission of H2 in K band

    NASA Astrophysics Data System (ADS)

    Lemaire, J.-L.; Field, D.; Pineau Des Forets, G.; Callejo, G.

    2002-06-01

    The observation of protostars in early stages of formation, is at the moment one of the major scientific goal of galactic astronomy. Important advances have been made in mm-wave radio-interferometry in identifying infall and accretion of material and in establishing the structure and evolution of circumstellar disks, in the inner reaches of which planets may form. In conjunction with still scarce observations, numerous theoretical models describe how disks may be created, which role is played by the angular momentum and the magnetic fields and how fast outflows of matter, recognised to be the signature of early star-formation, may develop. We exploit in this work the capability of the ISAAC instrument at ESO-VLT to detect extremely weak signals in the infrared (IR), reporting for the first time deep IR observations, in K band around 2 m, of vibrationally excited molecular hydrogen in the direction of the Bok globule BHR 71, a region already known as protostellar. There have been very few observations of H2 emission demonstrably associated with protostellar cores, as opposed to jets and outflows which characterize them at longer distances, and the results presented here are the first of their kind for imaging and spectroscopy of H2 in the direction of a zone around a deeply embedded protostar, opening a new window on early star formation. Our data show clearly, in the region of the IRS2 protostar (Class 0), two zones of vibrationally excited H2, separated by a narrow and darker lane. The morphology, dimensions and orientation of this lane, located at right-angles to the known outflow from IRS2, suggest its identification as a circumstellar disk. This interpretation is corroborated by the similitude of the H2 emission spectrum observed in this region with the spectrum observed at the bright apex of the other known protostar IRS1 (Class 1). An analysis of the H2 emission spectra, related to J-shocks models, shows that the gas is heated largely by processes of outflow and accretion intrinsic to the protostar.

  1. Field-induced hot-electron emission model for wide-band-gap semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Zeng, J. Z.; Deng, S. Z.; She, J. C.; He, H.; Xu, N. S.

    2010-09-01

    For field emission from wide-band-gap semiconductor nanostructures, nonlinear plots on Fowler-Nordheim (FN) coordinates and unacceptably large field enhancement factors (?FN) are often obtained by fitting based on FN equation. In the present work, the field-induced hot-electron emission model is developed and is found to give theoretical findings consistent with the experimental observation. The hot electrons are produced by heating effect of penetration field into the emitting tip of the nanostructure. This energy is expressed by effective electron temperature Te, which is much higher than the temperature of bulk structure. By combining the effective electron temperature with thermal emission function and Murphy and Good integration function, the relation between emission current density and external field is derived and the field enhancement factor (?Te) can be calculated quantitatively. For evaluation of the theoretical model, ZnO nanostructure is selected as a concrete example. The results are found to agree with experiment findings. Extremely large field enhancement factor is not needed in our model and nonlinear property of saturation region emerges in nature in our calculation.

  2. Multi-band constraints on the nature of emission line galaxies

    E-print Network

    Balmaverde, B

    2012-01-01

    Our aim is to explore the nature of emission line galaxies by combining high-resolution observations obtained in different bands to understand which objects are powered by an Active Galactic Nucleus(AGN). From the spectroscopic Palomar survey of nearby bright galaxies, we selected a sample of 18 objects observed with HST, Chandra, and VLA. No connection is found between X-ray and emission line luminosities from ground-based data, unlike what is found for brighter AGN. Conversely, a strong correlation emerges when using the HST spectroscopic data, which are extracted on a much smaller aperture. This suggests that the HST data better isolate the AGN component when one is present, while ground-based line measurements are affected by diffuse emission from the host galaxies. The sample separates into two populations. The 11 objects belonging to the first class have an equivalent width of the [OIII] emission line measured from HST data EW([OIII])>~2 A and are associated with an X-ray nuclear source; in the second g...

  3. The solar wind control of Jupiter's broad-band kilometric radio emission

    NASA Technical Reports Server (NTRS)

    Barrow, C. H.; Leblanc, Y.; Desch, M. D.

    1988-01-01

    Observations of the solar wind close to Jupiter are compared with the broad-band kilometric radio emission (bKOM), using data recorded by Voyager 1 and Voyager 2 during 1979. The lower bKOM frequencies, less than about 300 kHz, are found to correlate with the solar wind density and pressure and with the interplanetary magnetic field (IMF) magnitude during periods when there is a well-defined magnetic sector structure. The results suggest that lower frequency bKOM events are most likely to occur after a sector boundary has passed Jupiter during the period when the solar wind density and the IMF magnitude are increasing towards the sector center. The average bKOM energy per Jovian rotation tends to have lower values soon after the sector center has passed. Higher-frequency/higher-energy bKOM emission may be contaminated by hectometric emission (HOM) and differently correlated with solar activity. The solar wind control may also be obscured by some stronger control. It is suggested that electron density fluctuations in the Io torus, where the source is believed to be located, may be responsible for variations in the beaming and hence variations in the observed emission.

  4. Synthesis, crystal and electronic structures of new narrow-band-gap semiconducting antimonide oxides RE(3)SbO(3) and RE(8)Sb(3-delta)O(8), with RE = La, Sm, Gd, and Ho.

    PubMed

    Wang, Peng; Forbes, Scott; Kolodiazhnyi, Taras; Kosuda, Kosuke; Mozharivskyj, Yurij

    2010-06-30

    In the search for high-temperature thermoelectric materials, two families of novel, narrow-band-gap semiconducting antimonide oxides with the compositions RE(3)SbO(3) and RE(8)Sb(3-delta)O(8) (RE = La, Sm, Gd, Ho) have been discovered. Their synthesis was motivated by attempts to open a band gap in the semimetallic RESb binaries through a chemical fusion of RESb and corresponding insulating RE(2)O(3). Temperatures of 1350 degrees C or higher are required to obtain these phases. Both RE(3)SbO(3) and RE(8)Sb(3-delta)O(8) adopt new monoclinic structures with the C2/m space group and feature similar REO frameworks composed of "RE(4)O" tetrahedral units. In both structures, the Sb atoms occupy the empty channels within the REO sublattice. High-purity bulk Sm and Ho samples were prepared and subjected to electrical resistivity measurements. Both the RE(3)SbO(3) and RE(8)Sb(3-delta)O(8) (RE = Sm, Ho) phases exhibit a semiconductor-type electrical behavior. While a small band gap in RE(3)SbO(3) results from the separation of the valence and conduction bands, a band gap in RE(8)Sb(3-delta)O(8) appears to result from the Anderson localization of electrons. The relationship among the composition, crystal structures, and electrical resistivity is analyzed using electronic structure calculations. PMID:20524656

  5. Aminorhodamine (ARh): A Bichromophore with Three Emission Bands in Low Temperature Glasses.

    PubMed

    Sørensen, Thomas Just; Kilså, Kristine; Laursen, Bo W

    2015-06-01

    At first glance, aminorhodamine (ARh) is a typical pH responsive fluorescent, rhodamine-type dye. However, hidden under the typical rhodamine absorption band, ARh has another electronic transition of similar energy, but polarized orthogonal to that of the rhodamine chromophore. This transition-assigned to an arylpyrylium type chromophore contained in the system-is responsible for the sensor action of the dye. ARh is non-fluorescent, while protonation of a donor amino group turn on a strong rhodamine-type emission. At low temperature in frozen solution emission from both electronic subsystems of ARh are observed. In order to achieve more complete understanding of the photophysical mechanisms in this type of fluorescent probes, ARh and its protonated counterpart HARh were studied by absorption and fluorescence spectroscopy, computational chemistry, and at low temperatures in solid solution. Results from fluorescence anisotropy and time-resolved fluorescence spectra establish a bichromophore model and suggest that a remarkable weak coupling between the two nearly isoenergetic excited states in ARh enables the dual emission. All the complicated properties observed for ARh was accounted for by a bichromophore model describing the electronic system of ARh as a bichromophore constituted by a rhodamine and an arylpyrylium subsystem. PMID:25916892

  6. Performance of MODIS Thermal Emissive Bands On-orbit Calibration Algorithms

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Chang, T.

    2009-01-01

    Two nearly identical copies of the Moderate Resolution Imaging Spectroradiometer (MODIS) are currently operated on-board the Terra and Aqua spacecrafts, launched in December 1999 and May 2002, respectively. Together, they have produced an unprecedented amount of science data products, which are widely used for the studies of changes in the Earth's system of land, oceans, and atmosphere. MODIS is a cross-track scanning radiometer, which uses a two-sided scan mirror and collects data continuously over a wide scan angle range (+/-55 degree relative to the instrument nadir) each scan of 1.47 seconds. It has 36 spectral bands with wavelengths ranging from visible (VIS) to long-wave infrared (LWIR). MODIS bands 1-19 and 26 are the reflective solar bands (RSB) and bands 20-25 and 27-36 are the thermal emissive bands (TEB). MODIS was developed and designed with improvements made over its heritage sensors (such as AVHRR and Landsat) and, in particular, with more stringent calibration requirements. Because of this, MODIS was built with a set of state-of-art on-board calibrators (OBC), which include a solar diffuser (SD), a solar diffuser stability monitor (SDSM), a blackbody (BB), a spectroradiometric calibration assembly (SRCA), and a space view (SV) port. With the exception of view angle differences, MODIS OBC measurements and the Earth View (EV) observations are made via the same optical path. MODIS TEB have a total of 160 individual TEB detectors (10 per band), which are located on two cold focal plane assemblies (CFPA). For nominal on-orbit operation, the CFPA temperature is controlled at 83K via a passive radiative cooler. For the TEB, the calibration requirements at specified typical scene radiances are less than or equal to 1% with an exception for the fire detection (low gain) band. MODIS TEB on-orbit calibration is performed on a scan-by-scan basis using a quadratic calibration algorithm, and data collected from sensor responses to the onboard BB and SV. The BB serves as the thermal calibration source and the SV provides measurements for the sensor's background and offsets. MODIS on-board BB is a v-grooved plate with its temperature measured using 12 platinum resistive thermistors (PRT) uniformly embedded in the BB substrate. All the BB thermistors were characterized pre-launch with reference to the NIST temperature standards. Unlike typical BB operations in many heritage sensors, which have no temperature control capability, the MODIS on-board BB can be operated at any temperatures between instrument ambient (about 270K) and 315K and can also be varied continuously within this range. This feature has significantly enhanced the MODIS' capability of tracking and updating the TEB nonlinear calibration coefficients over its entire mission. Following a brief description of MODIS TEB on-orbit calibration methodologies and its onboard BB operational activities, this paper provides a comprehensive performance assessment of MODIS TEB quadratic calibration algorithm. It examines the scan-by-scan, orbit-by-orbit, daily, and seasonal variations of detector responses and associated impact due changes in the CFPA and instrument temperatures. Specifically, this paper will analyze the contribution by each individual thermal emissive source term (BB, scan cavity, and scan mirror), the impact on the Level 1 B data product quality due to pre-launch and on-orbit calibration uncertainties. A comparison of Terra and Aqua TEB on-orbit performance, lessons learned, and suggestions for future improvements will also be made.

  7. On-orbit characterization of RVS for MODIS thermal emissive bands

    NASA Astrophysics Data System (ADS)

    Xiong, Xiaoxiong; Salomonson, Vincent V.; Chiang, Kwo-Fu; Wu, Aisheng; Guenther, Bruce W.; Barnes, William

    2004-12-01

    Response versus scan angle (RVS) is a key calibration parameter for remote sensing radiometers that make observations using a scanning optical system, such as a doubled sided scan mirror (MODIS and GLI) or a rotating telescope (SeaWiFS and VIIRS). This is because the calibration is typically performed at a fixed viewing angle whereas the Earth scene observations are made over a range of viewing angles and the system"s response is a function of the scan angle. The NASA EOS Terra MODIS has been in operation for more than four years since its launch in December 1999. It has 36 spectral bands covering wavelengths from visible (VIS) to long-wave infrared (LWIR). It is a cross-track scanning radiometer with a two-sided paddle wheel scan mirror, making observations over a wide field of view (FOV) of +/-55° from nadir thereby enabling frequent global coverage. Due to pre-launch measurement limitations, the Terra MODIS thermal emissive bands (TEB) RVS characterization did not produce valid data sets that could be used to derive a reliable system level RVS. Because of this, a RVS was developed for use at launch and subsequent efforts have been made to characterize the RVS using on-orbit observations. This paper describes the Terra MODIS on-orbit characterization of TEB RVS, including the data from scanning the instrument"s closed nadir aperture door (CNAD) and the use of Earth view data collected during spacecraft deep space maneuvers (DSM). Comparisons of pre-launch analysis and early on-orbit measurements are also provided. Noticeable improvements have been made for several thermal emissive bands for observations at large angles of incidence (AOI). Using the correct RVS improves the image quality and the radiometric calibration accuracy. For bands 34-36, an adjustment of as much as 0.5-1.5K can be made at the end of scan (worst case) for mirror side 2. The impacts at smaller AOI and from mirror side 1 are much smaller. Based on RVS comparison studies and science test results, the on-orbit derived DSM RVS has been chosen for the ongoing L1B data processing and future reprocessing.

  8. Impact of Conifer Forest Litter on Microwave Emission at L-Band

    NASA Technical Reports Server (NTRS)

    Kurum, Mehmet; O'Neill, Peggy E.; Lang, Roger H.; Cosh, Michael H.; Joseph, Alicia T.; Jackson, Thomas J.

    2011-01-01

    This study reports on the utilization of microwave modeling, together with ground truth, and L-band (1.4-GHz) brightness temperatures to investigate the passive microwave characteristics of a conifer forest floor. The microwave data were acquired over a natural Virginia Pine forest in Maryland by a ground-based microwave active/passive instrument system in 2008/2009. Ground measurements of the tree biophysical parameters and forest floor characteristics were obtained during the field campaign. The test site consisted of medium-sized evergreen conifers with an average height of 12 m and average diameters at breast height of 12.6 cm. The site is a typical pine forest site in that there is a surface layer of loose debris/needles and an organic transition layer above the mineral soil. In an effort to characterize and model the impact of the surface litter layer, an experiment was conducted on a day with wet soil conditions, which involved removal of the surface litter layer from one half of the test site while keeping the other half undisturbed. The observations showed detectable decrease in emissivity for both polarizations after the surface litter layer was removed. A first-order radiative transfer model of the forest stands including the multilayer nature of the forest floor in conjunction with the ground truth data are used to compute forest emission. The model calculations reproduced the major features of the experimental data over the entire duration, which included the effects of surface litter and ground moisture content on overall emission. Both theory and experimental results confirm that the litter layer increases the observed canopy brightness temperature and obscure the soil emission.

  9. Aqua MODIS Thermal Emissive Band On-Orbit Calibration, Characterization, and Performance

    NASA Technical Reports Server (NTRS)

    Xiong, Xiaoxiong; Wenny, Brian N.; Wu, Aisheng; Barnes, William L.; Salomonson, Vincent V.

    2009-01-01

    The NASA's Earth Observing System Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) has continued to operate with satisfactory performance since its launch in May 2002, exceeding its nominal six-year design lifetime. Its continuous Earth observations have been used to generate many science data products for studies of the Earth's, system. MODIS has 36 spectral bands; 20 reflective solar bands and 16 thermal emissive bands (TEBs). All TEB observations are made at 1-km nadir spatial resolution with spectral wavelengths from 3.7 to 14.4 pm. Primary applications of MODIS TEB 'include surface, cloud, and atmospheric temperatures, water vapor, and cloud top altitude. MODIS TEB on-orbit calibration uses a quadratic algorithm with its calibration coefficients derived using an onboard blackbody (BB). This paper will present Aqua MODIS TEB on-orbit calibration, characterization, and performance over its six-year mission. Examples of instrument thermal behavior, BB temperature stability, detector short-term stability, and changes in long-term response (or system gain) will be presented. Comparisons will also be made with Terra MODIS, launched in December 1999. On-orbit results show that Aqua MODIS and its focal plane temperatures have behaved normally. BB temperature has remained extremely stable with typical scan -to-scan variations of less than +/-0.15 mK. Most TEB detectors continue to exceed their specified signal-to-noise ratio requirements, exhibiting excellent short-term stability and calibration accuracy. Excluding a few noisy detectors, either identified prelaunch or occurring postlaunch, on-orbit changes in TEB responses have been less than 0.5% on an annual basis. By comparison; the overall Aqua TEB performance has been better than that of Terra MODIS,

  10. On-orbit Characterization of RVS for MODIS Thermal Emissive Bands

    NASA Technical Reports Server (NTRS)

    Xiong, X.; Salomonson, V.; Chiang, K.; Wu, A.; Guenther, B.; Barnes, W.

    2004-01-01

    Response versus scan angle (RVS) is a key calibration parameter for remote sensing radiometers that make observations using a scanning optical system, such as a scan mirror in MODIS and GLI or a rotating telescope in SeaWiFS and VIIRS, since the calibration is typically performed at a fixed viewing angle while the Earth scene observations are made over a range of viewing angles. Terra MODIS has been in operation for more than four years since its launch in December 1999. It has 36 spectral bands covering spectral range from visible (VIS) to long-wave infrared (LWIR). It is a cross-track scanning radiometer using a two-sided paddle wheel scan mirror, making observations over a wide field of view (FOV) of +/-55 deg from the instrument nadir. This paper describes on-orbit characterization of MODIS RVS for its thermal emissive bands (TEB), using the Earth view data collected during Terra spacecraft deep space maneuvers (DSM). Comparisons with pre-launch analysis and early on-orbit measurements are also provided.

  11. High-Resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons: Shining Light on the Interstellar 3 Micron Emission Bands

    NASA Astrophysics Data System (ADS)

    Maltseva, Elena; Candian, Alessandra; Tielens, Xander; Petrignani, Annemieke; Oomens, J.; Buma, Wybren Jan

    2015-06-01

    Various astronomical objects show distinctive series of IR emission bands indicated as unidentified infrared emission bands. These features are nowadays mainly attributed to the IR fluorescence of Polycyclic Aromatic Hydrocarbons (PAHs) even though an unambiguous identification of which PAHs are involved has not been possible yet. We present here a high-resolution IR absorption study of a number of jet-cooled polycyclic aromatic hydrocarbons in the 3.3 ?m region obtained by IR-UV ion depletion techniques. The experimental spectra display many more bands than expected, and lead to the conclusion that the appearance of the spectrum is dominated by fourth-order vibrational coupling terms. This has far-reaching consequences since up till now the assignment of infrared emission features observed in different types of space objects in this wavelength region -and the conclusions drawn from these assignments on the evolution of interstellar gas- has relied heavily on harmonic quantum chemical calculations. We also observe that the presence of bay-hydrogen sites in a PAH leads to a shift of the overall spectrum to the high-energy side and to a broadening of the 3 ?m band. This observation provides an appealing explanation for previous speculations that the emission of 3 ?m band consists of two components. Moreover, it paves for using this structure to derive the composition of different objects.

  12. Model for Cameron band emission in comets: A case for EPOXI mission target comet 103P/Hartley 2

    E-print Network

    Bhardwaj, Anil

    2010-01-01

    The CO2 production rate has been derived in comets using the Cameron band (a3Pi - X1Sigma) emission of CO molecule assuming that photodissociative excitation of CO2 is the main production mechanism of CO in a3Pi metastable state. We have devoloped a model for the production and loss of CO(a3Pi) which has been applied to comet 103P/Hartley 2: the target of EPOXI mission. Our model calculations show that photoelectron impact excitation of CO and dissociative excitation of CO2 can together contribute about 60-90% to the Cameron band emission. The modeled brightness of (0-0) Cameron band emission on comet Hartley 2 is consistent with Hubble Space Telescope observations for 3-5% CO2 (depending on model input solar flux) and 0.5% CO relative to water, where photoelectron impact contribution is about 50-75%. We suggest that estimation of CO2 abundances on comets using Cameron band emission may be reconsidered. We predict the height integrated column brightness of Cameron band of ~1300 R during EPOXI mission encounte...

  13. Wurtzite CuGaO2: a new direct and narrow band gap oxide semiconductor applicable as a solar cell absorber.

    PubMed

    Omata, Takahisa; Nagatani, Hiraku; Suzuki, Issei; Kita, Masao; Yanagi, Hiroshi; Ohashi, Naoki

    2014-03-01

    An oxide semiconductor ?-CuGaO2 with a wurtzite-derived ?-NaFeO2 structure has been synthesized. Structural characterization has been carried out by Rietveld analysis using XRD and SAED, and it was shown that the lattice size is very close to that of zinc oxide. The optical absorption spectrum indicated that the band gap is 1.47 eV, which matches the band gap required to achieve the theoretical maximum conversion efficiency for a single-junction solar cell. The thermoelectromotive force indicated p-type conduction in its intrinsic state. Density functional theory calculations were performed to understand the electronic structure and optical properties of the semiconductor. These calculations indicated that ?-CuGaO2 is a direct semiconductor and intense absorption of light occurs near the band edge. These properties render this new material promising as an absorber in solar cells. PMID:24555768

  14. CH^+ Spectrum and Diffuse Interstellar Bands Toward Herschel 36 Excited by Dust Emission

    NASA Astrophysics Data System (ADS)

    Dahlstrom, Julie; Oka, Takeshi; Johnson, Sean; Welty, Daniel E.; Hobbs, Lew M.; York, Donald G.

    2012-06-01

    All electronic CH^+ interstellar absorption lines so far observed had been limited to the R(0) transition starting from the J = 0 ground level; this is because of the very rapid J = 1 ? 0 spontaneous emission with the life time of ˜ 140 s. We have observed the R(1) and Q(1) lines of the A^1? ? X^1? band from the excited J = 1 level 40.08 K (27.86 cm-1) above the J = 0 level toward Herschel 36 indicating high radiative temperature of T_r = 17.5 K. The high temperature is most likely due to far infrared dust emission from the Her 36 SE. We have also observed the R_1(3/2) line of CH starting from the excited fine structure level J = 3/2 which is 25.76 - 25.57 K above the J = 1/2 level. The effect of high radiative temperature is also noticed as unique lineshapes of diffuse interstellar bands (DIBs) observed toward Her 36. We have examined seven DIBs including ? 5780.5, ? 5797.1, ? 6190.0, and ? 6613.0 that are correlated with each other with correlation coefficients > 0.93. While for ordinary sightlines the lineshapes of these DIBs are more or less symmetric, those toward Her 36 show a long tail toward the red. This is due to far infrared pumping of high J rotational levels of polar carriers of the DIBs by the dust emission. We have developed a model calculation of relaxation taking into account of both radiative and collisional processes. A linear molecule with about 6 carbon atoms can explain some of the DIBs. For the DIBs we have examined, probably the carriers are of this size since we cannot explain the large difference between the DIBs toward ordinary sightlines and toward Her 36 with larger molecules. Goto, M., Stecklum, B., Linz, H., Feldt, M., Henning, Th., Pascucci, I., and Usuda, T. 2006, ApJ, {649} 299.

  15. Use of IRI to Model the Effect of Ionosphere Emission on Earth Remote Sensing at L-Band

    NASA Technical Reports Server (NTRS)

    Abraham, Saji; LeVine, David M.

    2004-01-01

    Microwave remote sensing in the window at 1.413 GHz (L-band) set aside for passive use only is important for monitoring sea surface salinity and soil moisture. These parameters are important for understanding ocean dynamics and energy exchange between the surface and atmosphere, and both NASA and ESA plan to launch satellite sensors to monitor these parameters at L-band (Aquarius, Hydros and SMOS). The ionosphere is an important source of error for passive remote sensing at this frequency. In addition to Faraday rotation, emission from the ionosphere is also a potential source of error at L-band. As an aid for correcting for emission, a regression model is presented that relates ionosphere emission to the integrated electron density (TEC). The goal is to use TEC from sources such as TOPEX, JASON or GPS to obtain estimates of emission over the oceans where the electron density profiles needed to compute emission are not available. In addition, data will also be presented to evaluate the use of the IRI for computing emission over the ocean.

  16. The ground-based H-, K-, and L-band absolute emission spectra of HD 209458b

    SciTech Connect

    Zellem, Robert T.; Griffith, Caitlin A.; Deroo, Pieter; Swain, Mark R.; Waldmann, Ingo P.

    2014-11-20

    Here we explore the capabilities of NASA's 3.0 m Infrared Telescope Facility (IRTF) and SpeX spectrometer and the 5.08 m Hale telescope with the TripleSpec spectrometer with near-infrared H-, K-, and L-band measurements of HD 209458b's secondary eclipse. Our IRTF/SpeX data are the first absolute L-band spectroscopic emission measurements of any exoplanet other than the hot Jupiter HD 189733b. Previous measurements of HD 189733b's L band indicate bright emission hypothesized to result from non-LTE CH{sub 4} ?{sub 3} fluorescence. We do not detect a similar bright 3.3 ?m feature to ?3?, suggesting that fluorescence does not need to be invoked to explain HD 209458b's L-band measurements. The validity of our observation and reduction techniques, which decrease the flux variance by up to 2.8 orders of magnitude, is reinforced by 1? agreement with existent Hubble/NICMOS and Spitzer/IRAC1 observations that overlap the H, K, and L bands, suggesting that both IRTF/SpeX and Palomar/TripleSpec can measure an exoplanet's emission with high precision.

  17. Structural phase transition, narrow band gap, and room-temperature ferromagnetism in [KNbO{sub 3}]{sub 1?x}[BaNi{sub 1/2}Nb{sub 1/2}O{sub 3??}]{sub x} ferroelectrics

    SciTech Connect

    Zhou, Wenliang; Yang, Pingxiong Chu, Junhao; Deng, Hongmei

    2014-09-15

    Structural phase transition, narrow band gap (E{sub g}), and room-temperature ferromagnetism (RTFM) have been observed in the [KNbO{sub 3}]{sub 1?x}[BaNi{sub 1/2}Nb{sub 1/2}O{sub 3??}]{sub x} (KBNNO) ceramics. All the samples have single phase perovskite structure, but exhibit a gradual transition behaviour from the orthorhombic to a cubic structure with the increase of x. Raman spectroscopy analysis not only corroborates this doping-induced change in normal structure but also shows the local crystal symmetry for x ? 0.1 compositions to deviate from the idealized cubic perovskite structure. A possible mechanism for the observed specific changes in lattice structure is discussed. Moreover, it is noted that KBNNO with compositions x?=?0.1–0.3 have quite narrow E{sub g} of below 1.5?eV, much smaller than the 3.2?eV band gap of parent KNbO{sub 3} (KNO), which is due to the increasing Ni 3d electronic states within the gap of KNO. Furthermore, the KBNNO materials present RTFM near a tetragonal to cubic phase boundary. With increasing x from 0 to 0.3, the magnetism of the samples develops from diamagnetism to ferromagnetism and paramagnetism, originating from the ferromagnetic–antiferromagnetic competition. These results are helpful in the deeper understanding of phase transitions, band gap tunability, and magnetism variations in perovskite oxides and show the potential role, such materials can play, in perovskite solar cells and multiferroic applications.

  18. Alterations in Cochlear Function after Exposure to Short Term Broad Band Noise Assessed by Otoacoustic Emissions

    PubMed Central

    Reddy, Prasen; M M, Kavitha; Khavasi, Prabhu; Doddamani, S S

    2014-01-01

    Background: Sudden or chronic exposure to sound alters the functioning of cochlea. This results in temporary or permanent alteration of functioning of cochlear cells. Alteration of functioning of outer hair cells (OHC) of cochlea following exposure to noise can be assessed by measurement of transient otoacoustic emissions (TEOAE). Such a measurement is of great clinical importance in early detection of the damage to the OHC. Aim: In this study we aim to study effect of noise on outer hair cell function by studying the changes in TEOAE’s amplitude following exposure to short term broad band noise in healthy volunteers. Materials and Methods: Twenty volunteers’ ten males and ten females participated in the study. They underwent pure tone and impedance audiometry to rule out ear pathology. Then pre-exposure TEOAE’s were recorded. After that they were exposed to broad band noise for two minutes. After gap of five minutes again TEOAE’s were recorded. Pre and post exposure amplitude of TEOAE’s was analysed statistically.s Results: There was statistically significant difference between pre exposure and post-exposure amplitude of TEOAE’s. Pre and post exposure values for A & B amplitudes showed p-value of 0.0001 whereas values for A-B amplitude showed p-value of 0.0001. Conclusion: Measurement of TEOAE’s can detect early changes in the functioning of outer hair cells which cannot be picked by routine pure tone audiometry. Thus they can be used in assessing early changes in cochlear function following exposure to noise in individuals exposed to sudden noise or working in noisy environments. Thus preventive methods to reduce the noise induced hearing loss in such individuals can be implemented. PMID:25386468

  19. Broad M-band multi-keV x-ray emission from plasmas created by short laser pulses

    SciTech Connect

    Harmand, M.; Dorchies, F.; Peyrusse, O.; Descamps, D.; Fourment, C.; Hulin, S.; Petit, S.; Santos, J. J.

    2009-06-15

    The investigation of the broad M-band x-ray emission from high-Z plasmas created by a laser, with a 30 fs to 3 ps pulse duration and achieving 10{sup 15-17} W/cm{sup 2} on target, is reported. Experimental emission spectra are measured in the energy range from 1.50 to 1.75 keV and discussed as potential backlighting x-ray sources for time-resolved x-ray absorption spectroscopy studies. They are compared with theoretical nonlocal thermodynamic equilibrium calculations of x-ray emission.

  20. The mid-infrared emission of narrow-line active galactic nuclei: Star formation, nuclear activity, and two populations revealed by WISE

    SciTech Connect

    Rosario, David J.; Burtscher, Leonard; Davies, Richard; Genzel, Reinhard; Lutz, Dieter; Tacconi, Linda J.

    2013-12-01

    We explore the nature of the long-wavelength mid-infrared (MIR) emission of a sample of 13,000 local Type II (narrow-line) active galactic nuclei (AGNs) from the Sloan Digital Sky Survey (SDSS) using 12 ?m and 22 ?m photometry from the WISE all-sky survey. In combination with FIRST 1.4 GHz photometry, we show that AGNs divide into two relatively distinct populations or 'branches' in the plane of MIR and radio luminosity. Seyfert galaxies lie almost exclusively on an MIR-bright branch (Branch A), while low-ionization nuclear emission line galaxies (LINERs) are split evenly into Branch A and the MIR-faint Branch B. We devise various tests to constrain the processes that define the branches, including a comparison to the properties of pure star-forming inactive galaxies on the MIR-radio plane. We demonstrate that the total MIR emission of objects on Branch A, including most Seyfert galaxies, is governed primarily by host star formation, with ?15% of the 22 ?m luminosity coming from AGN-heated dust. This implies that ongoing dusty star formation is a general property of Seyfert host galaxies. We show that the 12 ?m broadband luminosity of AGNs on Branch A is suppressed with respect to star-forming galaxies, possibly due to the destruction of PAHs or deeper 10 ?m Si absorption in AGNs. We uncover a correlation between the MIR luminosity and [O III] ?5007 luminosity in AGNs. This suggests a relationship between the star formation rate and nuclear luminosity in the AGN population, but we caution on the importance of selection effects inherent to such AGN-dominated emission-line galaxies in driving such a correlation. We highlight the MIR-radio plane as a useful tool in comparative studies of star formation and nuclear activity in AGNs.

  1. Predicted Fe II Spectra plus UV through sub-mm Emission Line Fluxes for Other Species Arising in Narrow Line Regions of AGNs

    NASA Astrophysics Data System (ADS)

    Verner, Ekaterina; Bruhweiler, F. C.; Wills, B. J.

    2009-01-01

    Optical and UV spectra indicate pronounced Fe II emission from multitudinous lines superposed on the underlying UV and optical continua of Seyferts and QSOs. Although the intrinsic UV of the these objects exhibit strong Fe II emission arising in higher density Broad Line Region (BLR) gas, observations at visual wavelengths indicate Fe II originating in both BLR and lower density Narrow Line Region (NLR) gas. Our modeling of observed intrinsic UV Fe II emission produces better fits with both BLR and NLR components. We have calculated a grid of photoionization models appropriate for NLR, spanning a range of number density [log (n/cm-3) = 1.0 to 8.0], photoionizing flux [log (?/cm-2 s-1) = 10.0-18.0], microturbulence (? = 0, 2, 10, and 20 km s-1), and abundance (0.1, 0.5, 1.0 and 5 times solar). These models include the effects of cooling from Fe II. The effects of Fe II cooling and the use of a 371 versus an 830-level atom for Fe II in producing the Fe II emission spectra are explored. We present predicted Fe II spectra from the UV through the IR, plus fluxes of important lines of other species from the UV through the sub-mm wavelength range. These predictions, besides being relevant for studies of Fe II in AGNs, provide predicted fluxes for important lines for upcoming missions such as Herschel and SOPHIA. These results will be made available to researchers via the World Wide Web. We acknowledge the support of the National Science Foundation through grant AST-0607465 to CUA.

  2. C{sub 2} swan band emission intensity as a function of C{sub 2} density.

    SciTech Connect

    Goyette, A. N.; Lawler, J. E.; Anderson, L. W.; Gruen, D. M.; McCauley, T. G.; Zhou, D.; Krauss, A. R.; Univ. of Wisconsin

    1998-05-01

    We report the systematic comparison of the optical emission intensity of the d {sup 3}{Pi} {yields} a {sup 3}{Pi} (0, 0) vibrational band of the C{sub 2} Swan system with the absolute C{sub 2} concentration in Ar/H{sub 2}/CH{sub 4} and Ar/H{sub 2}/C{sub 60} microwave plasmas used in the deposition of nanocrystalline diamond. The absolute C{sub 2} concentration is obtained using white-light absorption spectroscopy. Emission intensity correlates linearly with C{sub 2} density for variations of several plasma parameters and across two decades of species concentration. Although optical emission intensity generally is not an accurate quantitative diagnostic for gas phase species concentrations, these results confirm the reliability of the (0,0) Swan band for relative determination of C{sub 2} density with high sensitivity under conditions used for hydrogen-deficient plasma-enhanced chemical vapor deposition of diamond.

  3. Journal of the Korean Physical Society, Vol. 43, No. 4, October 2003, pp. 565573 Detectability Test of H2 Lyman-Werner Band Emission

    E-print Network

    Pak, Soojong

    of H2 Lyman-Werner Band Emission for a Far-Ultraviolet Imaging Spectrograph FIMS Kwang-Il Seon, Soojong by far-ultraviolet (far-UV) photons and emits fluorescent emission in the far-UV bands and in the near time) required to detect PDRs with the Far-ultraviolet IMaging spectrograph (FIMS) onboard KAISTSAT-4

  4. S-NPP VIIRS Thermal Emissive Bands On-Orbit Calibration and Performance

    NASA Technical Reports Server (NTRS)

    Efremova, Boryana; McIntire, Jeff; Moyer, David; Wu, Aisheng; Xiong, Xiaoxiong

    2014-01-01

    Presented is an assessment of the on-orbit radiometric performance of the thermal emissive bands (TEB) of the Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument based on data from the first 2 years of operations-from 20 January 2012 to 20 January 2014. The VIIRS TEB are calibrated on orbit using a V-grooved blackbody (BB) as a radiance source. Performance characteristics trended over the life of the mission include the F factor-a measure of the gain change of the TEB detectors; the Noise Equivalent differential Temperature (NEdT)-a measure of the detector noise; and the detector offset and nonlinear terms trended at the quarterly performed BB warm-up cool-down cycles. We find that the BB temperature is well controlled and stable within the 30mK requirement. The F factor trends are very stable and showing little degradation (within 0.8%). The offsets and nonlinearity terms are also without noticeable drifts. NEdT is stable and does not show any trend. Other TEB radiometric calibration-related activities discussed include the on-orbit assessment of the response versus scan-angle functions and an approach to improve the M13 low-gain calibration using onboard lunar measurements. We conclude that all the assessed parameters comply with the requirements, and the TEB provide radiometric measurements with the required accuracy.

  5. Correlation between mechanical stress and optical property of SiO2/Ta2O5 multilayer UV narrow band filter deposited by plasma ion-assisted deposition

    NASA Astrophysics Data System (ADS)

    Wang, Jue; Maier, Robert L.

    2005-09-01

    Multilayer SiO2/Ta2O5 UV narrow-bandpass filters were deposited by a plasma ion-assisted process. The optimized PIAD process leads to densified multilayer coatings with a stabilized build-in compressive stress and un-shifted center wavelength. The correlation between stress reduction and center wavelength upward shift was established via post-deposition annealing at temperature ranging from 120 oC to 500 oC. Following 300 oC annealing, increased porosity and physical thickness of single layers of Ta2O5 and SiO2 were observed, via EMA modeling of ellipsometric data acquired around the quasi-Brewster angle. This is consistent with AFM measurement. The CWL upward shift was attributed to the micro-structural changes originating from intrinsic stress relaxation. Good agreement between the calculated CWL shift based on single layer test, and measured total CWL shift of the UV NBF suggests that the multilayer interfacial coupling effects might be ignorable for CWL shift and stress calculations.

  6. Design concepts for a high-impedance narrow-band 42 GHz power TWT using a fundamental/forward ladder-based circuit

    NASA Technical Reports Server (NTRS)

    Karp, A.

    1980-01-01

    A low-cost, narrowband, millimeter wave space communications TWT design was studied. Cold test interaction structure scale models were investigated and analyses were undertaken to predict the electrical and thermal response of the hypothetical 200 W TWT at 42 GHz and 21 kV beam voltage. An intentionally narrow instantaneous bandwidth (1%, with the possibility of electronic tuning of the center frequency over several percent) was sought with a highly dispersive, high impedance "forward wave' interaction structure based on a ladder (for economy in fabrication) and nonspace harmonic interaction, for a high gain rate and a short, economically focused tube. The "TunneLadder' interaction structure devised combines ladder properties with accommodation for a pencil beam. Except for the impedance and bandwidth, there is much in common with the millimeter wave helix TWTs which provided the ideal of diamond support rods. The benefits of these are enhanced in the TunneLadder case because of spatial separation of beam interception and RF current heating.

  7. Narrow spectral emission CaMoO{sub 4}: Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+} phosphor crystals for white light emitting diodes

    SciTech Connect

    Khanna, A.; Electrical, Computer and Systems Engineering Department, Rensselaer Polytechnic Institute, 110, 8th Street, Troy, New York, 12180 ; Dutta, P.S.

    2013-02-15

    Alkaline earth metal molybdates are promising candidates as a host material for high efficiency narrow spectral emission phosphors. These phosphors could potentially be used for the fabrication of phosphor-converted light emitting diodes (pc-LEDs). Phosphor crystals of calcium molybdate doped with rare earth dopant Ln{sup 3+}(Ln=Eu, Dy, Tb) grown using flux growth method have been shown to exhibit higher excitation efficiency than the powders synthesized by solid-state reaction process. Molybdenum (VI) oxide has been found to be a suitable flux for growing large size optically transparent high quality crystals at a temperature around 1100 Degree-Sign C. Using the excitation wavelengths of 465 nm, 454 nm and 489 nm for CaMoO{sub 4}: Eu{sup 3+}, CaMoO{sub 4}: Dy{sup 3+} and CaMoO{sub 4}: Tb{sup 3+}, respectively, intense emission lines at wavelengths of 615 nm, 575 nm and 550 nm were observed. The optimized doping concentrations of 12%, 2% and 5% for Eu{sup 3+}, Dy{sup 3+} and Tb{sup 3+}, respectively, provided the highest luminescence intensity. - Graphical Abstract: CaMoO{sub 4}: Eu{sup 3+} phosphor crystals grown using a molybdenum (VI) oxide flux exhibited around 1.5 times the emission intensity of powders obtained from solid-state reaction at the same synthesis temperature. These crystals were found to efficiently emit 615 nm red light when excited by near UV light up to a wavelength of 395 nm. Highlights: Black-Right-Pointing-Pointer CaMoO{sub 4}: Ln{sup 3+} (Ln=Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}) phosphor crystals were successfully grown using high temperature flux (solutions) containing molybdenum (VI) oxide or lithium chloride. Black-Right-Pointing-Pointer Narrow spectral emission at 615 nm, 575 nm and 550 nm, respectively, was observed from CaMoO{sub 4}: Ln{sup 3+} (Ln=Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}) phosphor crystals. Black-Right-Pointing-Pointer The optimized doping concentrations of Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+} in CaMoO{sub 4} for highest emission intensity were determined to be 12%, 2% and 5%, respectively. Black-Right-Pointing-Pointer The CaMoO{sub 4}: Ln{sup 3+} (Ln=Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}) phosphor crystals grown with molybdenum (VI) oxide flux exhibited 50% higher emission intensity compared to the crystals grown with lithium chloride flux and the powders synthesized by solid-state reaction.

  8. Strong interactions, narrow bands, and dominant spin-orbit coupling in Mott insulating quadruple perovskite CaCo3V4O12

    NASA Astrophysics Data System (ADS)

    Rhee, H. B.; Pickett, W. E.

    2014-11-01

    We investigate the electronic and magnetic structures and the character and direction of spin and orbital moments of the recently synthesized quadruple perovskite compound CaCo3V4O12 using a selection of methods from density functional theory. Implementing the generalized gradient approximation and the Hubbard U correction (GGA+U ), ferromagnetic spin alignment leads to half-metallicity rather than the observed narrow gap insulating behavior. Including spin-orbit coupling (SOC) leaves a Mott insulating spectrum but with a negligible gap. SOC is crucial for the Mott insulating character of the V d1 ion, breaking the dm =±1 degeneracy and also giving a substantial orbital moment. Evidence is obtained of the large orbital moments on Co that have been inferred from the measured susceptibility. Switching to the orbital polarization (OP) functional, GGA+OP+SOC also displays clear tendencies toward very large orbital moments but in its own distinctive manner. In both approaches, application of SOC, which requires specification of the direction of the spin, introduces large differences in the orbital moments of the three Co ions in the primitive cell. We study a fictitious but simpler cousin compound Ca3CoV4O12 (Ca replacing two of the Co atoms) to probe in a more transparent fashion the interplay of spin and orbital degrees of freedom with the local environment of the planar CoO4 units. The observation is made that the underlying mechanisms seem to be local to a CoO4 plaquette, and that there is very strong coupling of the size of the orbital moment to the spin direction. These facts strongly suggest noncollinear spins, not only on Co but on the V sublattice as well.

  9. InAs/InP/ZnSe Core/Shell/Shell Quantum Dots as Near-Infrared Emitters: Bright, Narrow-Band, Non-Cadmium Containing, and Biocompatible.

    PubMed

    Xie, Renguo; Chen, Kai; Chen, Xiaoyuan; Peng, Xiaogang

    2008-12-14

    High quality InAs/InP/ZnSe core/shell/shell quantum dots have been grown by a one-pot approach. This engineered quantum dots with unique near-infrared (NIR) fluorescence, possessing outstanding optical properties, and the biocompatibility desired for in vivo applications. The resulting quantum dots have significantly lower intrinsic toxicity compared to NIR emissive dots containing elements such as cadmium, mercury, or lead. Also, these newly developed ultrasmall non-Cd containing and NIR-emitting quantum dots showed significantly improved circulation half-life and minimal reticuloendothelial system (RES) uptake. PMID:20631914

  10. Hydrogenation of polycyclic aromatic hydrocarbons as a factor affecting the cosmic 6.2 micron emission band

    NASA Technical Reports Server (NTRS)

    Beegle, L. W.; Wdowiak, T. J.; Harrison, J. G.

    2001-01-01

    While many of the characteristics of the cosmic unidentified infrared (UIR) emission bands observed for interstellar and circumstellar sources within the Milky Way and other galaxies, can be best attributed to vibrational modes of the variants of the molecular family known as polycyclic aromatic hydrocarbons (PAH), there are open questions that need to be resolved. Among them is the observed strength of the 6.2 micron (1600 cm(-1)) band relative to other strong bands, and the generally low strength for measurements in the laboratory of the 1600 cm(-1) skeletal vibration band of many specific neutral PAH molecules. Also, experiments involving laser excitation of some gas phase neutral PAH species while producing long lifetime state emission in the 3.3 micron (3000 cm(-1)) spectral region, do not result in significant 6.2 micron (1600 cm(-1)) emission. A potentially important variant of the neutral PAH species, namely hydrogenated-PAH (H(N)-PAH) which exhibit intriguing spectral correlation with interstellar and circumstellar infrared emission and the 2175 A extinction feature, may be a factor affecting the strength of 6.2 micron emission. These species are hybrids of aromatic and cycloalkane structures. Laboratory infrared absorption spectroscopy augmented by density function theory (DFT) computations of selected partially hydrogenated-PAH molecules, demonstrates enhanced 6.2 micron (1600 cm(-1)) region skeletal vibration mode strength for these molecules relative to the normal PAH form. This along with other factors such as ionization or the incorporation of nitrogen or oxygen atoms could be a reason for the strength of the cosmic 6.2 micron (1600 cm(-1)) feature.

  11. Monitoring MRK 509: The Origin of the Reprocessor and Broad Band X-ray Spectrum of Narrow Line Seyfert 1 AKN 564

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.; Leighly, Karen M.

    1998-01-01

    The ten monitoring observations of Mrk 509 were made successfully between October 20 and November 26 last year. These observations were simultaneously with RXTE observations. A preliminary analysis of the RXTE observations has been done, and the light curve is shown in figure 1. Our aim in this experiment is to determine the location of the emission region of the reflection component by reverberation mapping. This component could be emitted from the accretion disk, within 100 Scwartzschild radii (R(sub s)) from the source. Note that the monitoring interval of 2.5 days corresponds to 100 R(sub s) for a 2 x 10(exp 8) solar mass black hole, which may be appropriate for this luminous object. In that case, we would expect the reflected component to vary along the direct flux, and there should be no spectral variability between observations. Alternatively, the reflected emission could come from the molecular torus, several parsecs from the nucleus. In that case, the reflection component flux should not vary. The light curve in figure 1 shows that during the monitoring period, the target varied in an ideal way, since significant variability was observed between observations and yet the most rapid variability is apparently sampled. The analysis of this data is not yet completed. The measurement of the reflection component in the combined ASCa and RXTE spectra depends critically on the RXTE background subtraction and calibration, but these have not yet progressed to the point where the analysis can be done.

  12. Coupling of narrow and wide band-gap semiconductors on uniform films active in bacterial disinfection under low intensity visible light: implications of the interfacial charge transfer (IFCT).

    PubMed

    Rtimi, S; Sanjines, R; Pulgarin, C; Houas, A; Lavanchy, J-C; Kiwi, J

    2013-09-15

    This study reports the design, preparation, testing and surface characterization of uniform films deposited by sputtering Ag and Ta on non-heat resistant polyester to evaluate the Escherichia coli inactivation by TaON, TaN/Ag, Ag and TaON/Ag polyester. Co-sputtering for 120 s Ta and Ag in the presence of N? and O? led to the faster E. coli inactivation by a TaON/Ag sample within ?40 min under visible light irradiation. The deconvolution of TaON/Ag peaks obtained by X-ray photoelectron spectroscopy (XPS) allowed the assignment of the Ta?O? and Ag-species. The shifts observed for the XPS peaks have been assigned to AgO to Ag?O and Ag(0), and are a function of the applied sputtering times. The mechanism of interfacial charge transfer (IFCT) from the Ag?O conduction band (cb) to the lower laying Ta?O? (cb) is discussed suggesting a reaction mechanism. The optical absorption of the TaON and TaON/Ag samples found by diffuse reflectance spectroscopy (DRS) correlated well with the kinetics of E. coli inactivation. The TaON/Ag sample microstructure was characterized by contact angle (CA) and by atomic force microscopy (AFM). Self-cleaning of the TaON/Ag polyester after each disinfection cycle enabled repetitive E. coli inactivation. PMID:23867967

  13. Reducing Contrast Contamination in Radial Turbo-Spin-Echo Acquisitions by Combining a Narrow-Band KWIC Filter With Parallel Imaging

    PubMed Central

    Neumann, Daniel; Breuer, Felix A.; Völker, Michael; Brandt, Tobias; Griswold, Mark A.; Jakob, Peter M.; Blaimer, Martin

    2014-01-01

    Purpose Cartesian turbo spin-echo (TSE) and radial TSE images are usually reconstructed by assembling data containing different contrast information into a single k-space. This approach results in mixed contrast contributions in the images, which may reduce their diagnostic value. The goal of this work is to improve the image contrast from radial TSE acquisitions by reducing the contribution of signals with undesired contrast information. Methods Radial TSE acquisitions allow the reconstruction of multiple images with different T2 contrasts using the k-space weighted image contrast (KWIC) filter. In this work, the image contrast is improved by reducing the band-width of the KWIC filter. Data for the reconstruction of a single image are selected from within a small temporal range around the desired echo time. The resulting data set is undersampled and therefore an iterative parallel imaging algorithm is applied to remove aliasing artifacts. Results Radial TSE images of the human brain reconstructed with the proposed method show an improved contrast when compared to Cartesian TSE images or radial TSE images with conventional KWIC reconstructions. Conclusion The proposed method provides multi-contrast images from radial TSE data with contrasts similar to multi spin-echo images. Contaminations from unwanted contrast weightings are strongly reduced. PMID:24436227

  14. Optical Observations of the Nearby Galaxy IC342 With Narrow Band [S II] and H? Filters. II - Detection of 16 Optically-Identified Supernova Remnant Candidates

    NASA Astrophysics Data System (ADS)

    Vu?eti?, M. M.; ?iprijanovi?, A.; Pavlovi?, M. Z.; Pannuti, T. G.; Petrov, N.; Göker, Ü. D.; Ercan, E. N.

    2015-11-01

    We present the detection of 16 optical supernova remnant (SNR) candidates in the nearby spiral galaxy IC342. The candidates were detected by applying [S II]/H? ratio criterion on observations made with the 2 m RCC telescope at Rozhen National Astronomical Observatory in Bulgaria. In this paper, we report the coordinates, diameters, H? and [S II] fluxes for 16 SNRs detected in two fields of view in the IC342 galaxy. Also, we estimate that the contamination of total H? flux from SNRs in the observed portion of IC342 is 1.4 percent. This would represent the fractional error when the star formation rate (SFR) for this galaxy is derived from the total galaxy's H? emission.

  15. L-Band H Polarized Microwave Emission During the Corn Growth Cycle

    NASA Technical Reports Server (NTRS)

    Joseph, A. T.; va der Velde, R.; O'Neill, P. E.; Kim, E.; Lang, R. H.; Gish, T.

    2012-01-01

    Hourly L-band (1.4 GHz) horizontally (H) polarized brightness temperatures (T(sub B))'s measured during five episodes (more than two days of continuous measurements) of the 2002 corn growth cycle are analyzed. These T(sub B)'s measurements were acquired as a part of a combined active/passive microwave field campaign, and were obtained at five incidence and three azimuth angles relative to the row direction. In support of this microwave data collection, intensive ground sampling took place once a week. Moreover, the interpretation of the hourly T(sub B)'s could also rely on the data obtained using the various automated instruments installed in the same field. In this paper, the soil moisture and temperature measured at fixed time intervals have been employed as input for the tau-omega model to reproduce the hourly T(sub B). Through the calibration of the vegetation and surface roughness parameterizations, the impact of the vegetation morphological changes on the microwave emission and the dependence of the soil surface roughness parameter, h(sub r), on soil moisture are investigated. This analysis demonstrates that the b parameter, appearing in the representation of the canopy opacity, has an angular dependence that varies throughout the growing period and also that the parameter hr increases as the soil dries in a portion of the dry-down cycle. The angular dependence of the b parameter imposes the largest uncertainty on T(sub B) simulations near senescence as the response of b to the incidence is also affected by the crop row orientation. On the other hand, the incorporation of a soil moisture dependent h(sub r) parameterization was responsible for the largest error reduction of T(sub B) simulations in the early growth cycle.

  16. DETECTION OF K{sub S} -BAND THERMAL EMISSION FROM WASP-3b

    SciTech Connect

    Zhao Ming; Wright, Jason; Milburn, Jennifer; Hinkley, Sasha; Barman, Travis; Swain, Mark R.; Monnier, John D.

    2012-03-20

    We report the detection of thermal emission from the hot Jupiter WASP-3b in the K{sub S} band, using a newly developed guiding scheme for the WIRC instrument at the Palomar Hale 200 inch telescope. Our new guiding scheme has improved the telescope guiding precision by a factor of {approx}5-7, significantly reducing the correlated systematics in the measured light curves. This results in the detection of a secondary eclipse with depth of 0.181% {+-} 0.020% (9{sigma})-a significant improvement in WIRC's photometric precision and a demonstration of the capability of Palomar/WIRC to produce high-quality measurements of exoplanetary atmospheres. Our measured eclipse depth cannot be explained by model atmospheres with heat redistribution but favors a pure radiative equilibrium case with no redistribution across the surface of the planet. Our measurement also gives an eclipse phase center of 0.5045 {+-} 0.0020, corresponding to an ecos {omega} of 0.0070 {+-} 0.0032. This result is consistent with a circular orbit, although it also suggests that the planet's orbit might be slightly eccentric. The possible non-zero eccentricity provides insight into the tidal circularization process of the star-planet system, but might also have been caused by a second low-mass planet in the system, as suggested by a previous transit timing variation study. More secondary eclipse observations, especially at multiple wavelengths, are necessary to determine the temperature-pressure profile of the planet's atmosphere and shed light on its orbital eccentricity.

  17. Room temperature spontaneous emission enhancement from quantum dots in photonic crystal slab cavities in the telecommunications C-band

    E-print Network

    Richard Hostein; Rémy Braive; Matthieu Larqué; Ko-Hsin Lee; Anne Talneau; Luc Le Gratiet; Isabelle Robert-Philip; Isabelle Sagnes; Alexios Beveratos

    2009-03-25

    We report on the control of the spontaneous emission dynamics from InAsP self-assembled quantum dots emitting in the telecommunications C-band and weakly coupled to the mode of a double heterostructure cavity etched on a suspended InP membrane at room temperature. The quality factor of the cavity mode is 44x10^3 with an ultra-low modal volume of the order of 1.2 lambda/n)^3, inducing an enhancement of the spontaneous emission rate of up a factor of 2.8 at 300 K.

  18. Effect of N2 and H2 plasma treatments on band edge emission of ZnO microrods

    PubMed Central

    Rodrigues, Joana; Holz, Tiago; Fath Allah, Rabie; Gonzalez, David; Ben, Teresa; Correia, Maria R.; Monteiro, Teresa; Costa, Florinda M.

    2015-01-01

    ZnO microrods were grown by laser assisted flow deposition technique in order to study their luminescence behaviour in the near band edge spectral region. Transmission electron microscopy analysis put in evidence the high crystallinity degree and microrod’s compositional homogeneity. Photoluminescence revealed a dominant 3.31?eV emission. The correlation between this emission and the presence of surface states was investigated by performing plasma treatments with hydrogen and nitrogen. The significant modifications in photoluminescence spectra after the plasma treatments suggest a connexion between the 3.31?eV luminescence and the surface related electronic levels. PMID:26027718

  19. Effect of N2 and H2 plasma treatments on band edge emission of ZnO microrods.

    PubMed

    Rodrigues, Joana; Holz, Tiago; Allah, Rabie Fath; Gonzalez, David; Ben, Teresa; Correia, Maria R; Monteiro, Teresa; Costa, Florinda M

    2015-01-01

    ZnO microrods were grown by laser assisted flow deposition technique in order to study their luminescence behaviour in the near band edge spectral region. Transmission electron microscopy analysis put in evidence the high crystallinity degree and microrod's compositional homogeneity. Photoluminescence revealed a dominant 3.31 eV emission. The correlation between this emission and the presence of surface states was investigated by performing plasma treatments with hydrogen and nitrogen. The significant modifications in photoluminescence spectra after the plasma treatments suggest a connexion between the 3.31 eV luminescence and the surface related electronic levels. PMID:26027718

  20. Estimating net rainfall, evaporation and water storage of a bare soil from sequential L-band emissivities

    NASA Technical Reports Server (NTRS)

    Stroosnijder, L.; Lascano, R. J.; Newton, R. W.; Vanbavel, C. H. M.

    1984-01-01

    A general method to use a time series of L-band emissivities as an input to a hydrological model for continuously monitoring the net rainfall and evaporation as well as the water content over the entire soil profile is proposed. The model requires a sufficiently accurate and general relation between soil emissivity and surface moisture content. A model which requires the soil hydraulic properties as an additional input, but does not need any weather data was developed. The method is shown to be numerically consistent.

  1. Comparison of D-X and B-X Molecular Band Emission from a Microwave Produced XeCl Discharge

    NASA Astrophysics Data System (ADS)

    Anderson, S. A.; Bernal, Sara; Glide, Carri; Anderson, R. B.; Brake, Mary

    2000-10-01

    Ultraviolet (UV) lamps are becoming increasingly important in the curing and material processing sectors of manufacturing. With the use of these lamps on the rise, the efficiency of these lamps, i.e. the amount of emission in the useful wavelength band, is becoming an important economical factor. A XeCl excimer plasma produces UV emission from several molecular transitions including D-X at 236 nm and B-X at 308 nm. This paper examines the relative light output from these two transitions from a microwave generated XeCl plasma. The effect of concentration, power, and pressure will be examined and the optimal conditions for light output in the various molecular bands will be discussed.

  2. VERY LONG BASELINE ARRAY IMAGING OF PARSEC-SCALE RADIO EMISSIONS IN NEARBY RADIO-QUIET NARROW-LINE SEYFERT 1 GALAXIES

    SciTech Connect

    Doi, Akihiro; Asada, Keiichi; Inoue, Makoto; Fujisawa, Kenta; Nagai, Hiroshi; Hagiwara, Yoshiaki; Wajima, Kiyoaki

    2013-03-01

    We conducted Very Long Baseline Array (VLBA) observations of seven nearby narrow-line Seyfert 1 (NLS1) galaxies at 1.7 GHz ({lambda}18 cm) with milliarcsecond resolution. This is the first systematic very long baseline interferometry study focusing on the central parsec-scale regions of radio-quiet NLS1s. Five of the seven were detected at a brightness temperature of {approx}> 5 Multiplication-Sign 10{sup 6} K and contain radio cores with high brightness temperatures of >6 Multiplication-Sign 10{sup 7} K, indicating a nonthermal process driven by jet-producing central engines as in radio-loud NLS1s and other active galactic nucleus classes. VLBA images of MRK 1239, MRK 705, and MRK 766 exhibit parsec-scale jets with clear linear structures. A large portion of the radio power comes from diffuse emission components that are distributed within the nuclear regions ({approx}< 300 pc), which is a common characteristic throughout the observed NLS1s. Jet kinetic powers limited by the Eddington limit may be insufficient to allow the jets to escape to kiloparsec scales for these radio-quiet NLS1s with low-mass black holes of {approx}< 10{sup 7} M {sub Sun }.

  3. Large-amplitude, narrow-linewidth microwave emission in a dual free-layer MgO spin-torque oscillator

    SciTech Connect

    Nagasawa, Tazumi Kudo, Kiwamu; Suto, Hirofumi; Mizushima, Koichi; Sato, Rie

    2014-11-03

    Synchronized magnetization motion among the several magnetic layers composing a spin-torque oscillator (STO) is considered an effective way to improve spectral purity. To utilize this scheme in a MgO-based STO, we have fabricated a dual free-layer STO composed of a CoFeB free layer (FL), a MgO barrier layer, and a CoFe/Ru/CoFeB synthetic ferrimagnet free layer (SyF). Unlike conventional MgO-based STOs, this structure does not have an antiferromagnetic layer that pins the SyF, leading to a large-amplitude oscillation of magnetization in the SyF. The dual free-layer STO exhibits coherent microwave emissions with power spectrum density beyond 800 nW/GHz and narrow spectral linewidth below 5?MHz (Q-factor???2000). Macrospin simulations confirm that the stable oscillations originate from the synchronized magnetization motion of the FL and the SyF through dynamical dipolar coupling.

  4. Wavelength Shifts of the 7.7 Micron Emission Band in Reflection Nebulae

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse; Temi, Pasquale

    2003-01-01

    Using spatial-spectral data cubes of reflection nebulae obtained by ISOCAM, we have observed a shift in the central wavelength of the 7.7 micron band within several reflection nebulae. The band shifts progressively from approx. 7.8 microns near the edge of the nebulae to approx. 7.6 microns towards the center of the nebulae. The ratio of the 11.3/7.7 micron bands also changes with distance from the central star, first rising from the center towards the edge of the nebula, then falling at the largest distances from the star, consistent with the 11.3/7.7 micron band ratio being controlled by the PAH ionization state. The behavior of the 7.7 micron band center can be explained either by assuming that anions are the origin of the 7.85 micron band and cations the 7.65 micron band, or that the band center wavelength depends on the chemical nature of the PAHs.

  5. Spectral Monitoring of Emission Band HeII+Ha^? in the Spectra of the Wolf-Rayet Type Star HD 192163 during 2005-2008

    NASA Astrophysics Data System (ADS)

    Rustamov, J. N.

    2008-12-01

    Results of investigation of the emission band HeII+Ha using 38 eshelle-spectrograms of the WR type star HD 192163 are presented. Observations carried out in 2005-2008 years at Cassegrain focus of 2-meter 'Zeiss' telescope of the ShAO named after N.Tusi of Azerbaijan National Academy of Sciences, using eshelle-spectrometer. Determined equivalent widths and radial velocity of emission band ^B^NII+^B<95>. Variability of these parameters with the Julian date and variability of the violet part (from Lamda=6496 <9e> to Lamda=6532 <9e>) of the emission band HeII+Ha is revealed.

  6. Investigation of Emission Band HeII+Ha in the Spectra of the Wolf-Rayet Type Star WR 136 = HD 192163

    NASA Astrophysics Data System (ADS)

    Rustamov, J. N.

    2007-06-01

    Results of investigation of the emission band HeII+Ha using 24 eshelle-spectrograms of the WR type star WR 136 = HD 192163 are presented. Observations carried out in 2005-2007 years at Cassegrain focus of 2-meter telescope of the ShAO named after N.Tusi of the National Academy of Sciences of the Azerbaijan, using eshelle-spectrometer. Determined various parameters of the emission band HeII+Ha: equivalent widths, radial velocity, central intensity, widths at half intensity. Variability of the violet part of the emission band HeII+Ha is revealed.

  7. Calculated hydroxyl A2 sigma --> X2 pi (0, 0) band emission rate factors applicable to atmospheric spectroscopy

    NASA Technical Reports Server (NTRS)

    Cageao, R. P.; Ha, Y. L.; Jiang, Y.; Morgan, M. F.; Yung, Y. L.; Sander, S. P.

    1997-01-01

    A calculation of the A2 sigma --> X2 pi (0, 0) band emission rate factors and line center absorption cross sections of OH applicable to its measurement using solar resonant fluorescence in the terrestrial atmosphere is presented in this paper. The most accurate available line parameters have been used. Special consideration has been given to the solar input flux because of its highly structured Fraunhofer spectrum. The calculation for the OH atmospheric emission rate factor in the solar resonant fluorescent case is described in detail with examples and intermediate results. Results of this calculation of OH emission rate factors for individual rotational lines are on average 30% lower than the values obtained in an earlier work.

  8. The circumstellar dust envelopes of red giant stars. I - M giant stars with the 10-micron silicate emission band

    NASA Technical Reports Server (NTRS)

    Hashimoto, O.; Nakada, Y.; Onaka, T.; Kamijo, F.; Tanabe, T.

    1990-01-01

    Spherical dust envelope models of red giant stars are constructed by solving the radiative transfer equations of the generalized two-stream Eddington approximation. The IRAS observations of M giant stars which show the 10-micron silicate emission band in IRAS LRS spectra are explained by the models with the dirty silicate grains with K proportional to lambda exp -1.5 for lambda greather than 28 microns. Under the assumption of steady mass flow in the envelope, this model analysis gives the following conclusions: (1) the strength of the silicate emission peak at 10 microns is a good indicator of the mass loss rate of the star, (2) no stars with the 10-microns silicate emission feature are observed in the range of mass loss rate smaller than 7 x 10 to the -8th solar mass/yr, and (3) the characteristic time of the mass loss process of M stars does not exceed a few 10,000 years.

  9. Spatially Resolved M-band Emission from Io's Loki Patera-Fizeau Imaging at the 22.8 m LBT

    NASA Astrophysics Data System (ADS)

    Conrad, Albert; de Kleer, Katherine; Leisenring, Jarron; La Camera, Andrea; Arcidiacono, Carmelo; Bertero, Mario; Boccacci, Patrizia; Defrère, Denis; de Pater, Imke; Hinz, Philip; Hofmann, Karl-Heinz; Kürster, Martin; Rathbun, Julie; Schertl, Dieter; Skemer, Andy; Skrutskie, Michael; Spencer, John; Veillet, Christian; Weigelt, Gerd; Woodward, Charles E.

    2015-05-01

    The Large Binocular Telescope Interferometer mid-infrared camera, LMIRcam, imaged Io on the night of 2013 December 24 UT and detected strong M-band (4.8 ?m) thermal emission arising from Loki Patera. The 22.8 m baseline of the Large Binocular Telescope provides an angular resolution of ˜32 mas (˜100 km at Io) resolving the Loki Patera emission into two distinct maxima originating from different regions within Loki’s horseshoe lava lake. This observation is consistent with the presence of a high-temperature source observed in previous studies combined with an independent peak arising from cooling crust from recent resurfacing. The deconvolved images also reveal 15 other emission sites on the visible hemisphere of Io including two previously unidentified hot spots.

  10. Observation of interface band structure by ballistic-electron-emission microscopy

    NASA Technical Reports Server (NTRS)

    Bell, L. D.; Kaiser, W. J.

    1988-01-01

    The paper reports an advanced ballistic electron spectroscopy technique that was used to directly measure semiconductor band structure properties at a subsurface interface. Two interface systems having contrasting band structures were investigated by this method: Au-Si and Au-GaAs. It is concluded that the proposed method, based on scanning tunneling microscopy, enables the spatially resolved carrier-transport spectroscopy of interfaces.

  11. The ALI-ARMS Code for Modeling Atmospheric non-LTE Molecular Band Emissions: Current Status and Applications

    NASA Technical Reports Server (NTRS)

    Kutepov, A. A.; Feofilov, A. G.; Manuilova, R. O.; Yankovsky, V. A.; Rezac, L.; Pesnell, W. D.; Goldberg, R. A.

    2008-01-01

    The Accelerated Lambda Iteration (ALI) technique was developed in stellar astrophysics at the beginning of 1990s for solving the non-LTE radiative transfer problem in atomic lines and multiplets in stellar atmospheres. It was later successfully applied to modeling the non-LTE emissions and radiative cooling/heating in the vibrational-rotational bands of molecules in planetary atmospheres. Similar to the standard lambda iterations ALI operates with the matrices of minimal dimension. However, it provides higher convergence rate and stability due to removing from the iterating process the photons trapped in the optically thick line cores. In the current ALI-ARMS (ALI for Atmospheric Radiation and Molecular Spectra) code version additional acceleration of calculations is provided by utilizing the opacity distribution function (ODF) approach and "decoupling". The former allows replacing the band branches by single lines of special shape, whereas the latter treats non-linearity caused by strong near-resonant vibration-vibrational level coupling without additional linearizing the statistical equilibrium equations. Latest code application for the non-LTE diagnostics of the molecular band emissions of Earth's and Martian atmospheres as well as for the non-LTE IR cooling/heating calculations are discussed.

  12. Pre-launch characterization of aqua MODIS scan mirror response versus scan angle for thermal emissive bands

    NASA Astrophysics Data System (ADS)

    Chiang, Kwo-Fu; Xiong, Xiaoxiong

    2007-09-01

    The double-sided paddle wheel scan mirror is the key optical component of the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the NASA EOS Terra and Aqua satellites. At a constant rotating speed, the scan mirror continuously reflects the Earth's top-of-atmosphere radiances through the instrument nadir aperture door and onto four focal plane assemblies (FPA), which consist of 36 spectral bands. Of those 36 bands, 16 are thermal emissive bands (TEB) with wavelengths ranging from 3.7 to 14.4?m. While this cross-track scanning system provides the Earth scene observations over a range of +/-55° viewing angles from the nadir, the on-orbit calibration for TEB is performed by an On-Board Calibrator Blackbody (OBC BB) at a fixed viewing angle. The response versus scan angle (RVS) of the scan mirror is sensitive to the MODIS radiometric calibration. This paper describes how the pre-launch TEB RVS of the Aqua MODIS was characterized at the instrument system level by using ground support equipment, a Blackbody Calibration Source (BCS). The RVS test setup, test procedure, data analysis, derivation of RVS, and the fitting uncertainty are discussed in the paper. A separate paper that gives similar RVS analysis for the MODIS Reflective Solar Bands (RSB) is presented in this proceeding.

  13. Active-Passive Synergy for Interpreting Ocean L-band Emissivity: Results from the CAROLS Airborne Campaigns

    NASA Technical Reports Server (NTRS)

    Martin, A.C.H.; Boutin, J.; Hauser, D.; Dinnat, E. P.

    2014-01-01

    The impact of the ocean surface roughness on the ocean L-band emissivity is investigated using simultaneous airborne measurements from an L-band radiometer (CAROLS) and from a C-band scatterometer (STORM) acquired in the Gulf of Biscay (off-the French Atlantic coasts) in November 2010. Two synergetic approaches are used to investigate the impact of surface roughness on the L-band brightness temperature (Tb). First, wind derived from the scatterometer measurements is used to analyze the roughness contribution to Tb as a function of wind and compare it with the one simulated by SMOS and Aquarius roughness models. Then residuals from this mean relationship are analyzed in terms of mean square slope derived from the STORM instrument. We show improvement of new radiometric roughness models derived from SMOS and Aquarius satellite measurements in comparison with prelaunch models. Influence of wind azimuth on Tb could not be evidenced from our data set. However, we point out the importance of taking into account large roughness scales (>20 cm) in addition to small roughness scale (5 cm) rapidly affected by wind to interpret radiometric measurements far from nadir. This was made possible thanks to simultaneous estimates of large and small roughness scales using STORM at small (7-16) and large (30) incidence angles.

  14. Comparing Narrow- and Broad-line AGNs in a New Diagnostic Diagram for Emission-line Galaxies Based on WISE Data

    NASA Astrophysics Data System (ADS)

    Coziol, R.; Torres-Papaqui, J. P.; Andernach, H.

    2015-06-01

    Using a new color-color diagnostic diagram in the mid-infrared (MIR) built from WISE data, the MIRDD, we compare narrow-emission-line galaxies (NELGs) that exhibit different activity types (star-forming galaxies (SFGs) and active galactic nuclei (AGNs), i.e., LINERs, Seyfert 2 galaxies (Sy2s), and Transition-type Objects (TOs)), as determined using one standard diagnostic diagram in the optical (BPT-VO), with broad-line AGNs (QSOs and Sy1s) and BL Lac objects at low redshift (z?slant 0.25). We show that the BL Lac objects occupy the same region as the LINERs in the MIRDD, whereas the QSOs and Sy1s occupy an intermediate region between the LINERs and the Sy2s. In the MIRDD these galaxies trace a sequence that can be reproduced by a power law, {{F}? }={{? }? }, where the spectral index, ?, varies from 0 to -2, which is similar to what is observed in the optical/ultraviolet part of the spectra of AGNs with different luminosities. For the NELGs with different activity types, we perform a stellar-population synthesis analysis, confirming that their specific positions in the MIRD depend on their star formation histories (SFH) and demonstrating that the W2-W3 color is tightly correlated with the level of star formation in their host galaxies. In good agreement with the SFH analysis, a comparison of their MIR colors with the colors yielded by spectral energy distributions (SEDs) of galaxies with different activity types shows that the SED of the LINERs is similar to the SEDs of the QSOs and Sy1s, consistent with AGN galaxies with mild star formation, whereas the SEDs of the Sy2s and TOs are consistent with AGN galaxies with strong star formation components. For the BL Lac objects, we show that their blue MIR colors can only be fitted with an SED that has no star formation component, consistent with AGNs in elliptical-type galaxies. From their similarities in MIR colors and SEDs, we infer that, in the nearby universe, the level of star formation activity most probably increases in the host galaxies of emission-line galaxies with different activity types along the sequence BL Lac \\to LINER \\to QSO/Sy1 \\to Sy2 \\to TO \\to SFG.

  15. Serum levels of homocysteine, folate and vitamin B12 in patients with vitiligo before and after treatment with narrow band ultraviolet B phototherapy and in a group of controls.

    PubMed

    Ata?, Hatice; Cemil, Bengü Çevirgen; Gönül, Müzeyyen; Ba?türk, Eda; Çiçek, Emel

    2015-07-01

    The association between vitamin B12, folate, homocysteine and vitiligo were studied in several studies, but the results are contradictory. Narrow-band ultraviolet B (NBUVB) phototherapy is now considered as a gold standard for the treatment of diffuse vitiligo. The effects of NBUVB phototherapy on both vitamin B12, folate and homocysteine levels have not been studied in vitiligo patients yet. Serum levels of vitamin B12, folate and homocysteine were measured in vitiligo patients and control group and also both before and after NBUVB phototherapy in vitiligo patients. While levels of homocysteine in patients with vitiligo were significantly higher than controls (16.9±8.4 vs. 10. 9±3.4 ?mol/L; p<0,001) vitamin B12 and folate levels were not different (p>0.05). NBUVB phototherapy led to a 33.7±21.9% (0-75%) response in patients with vitiligo after 80 seccions. Treatment with NBUVB improved vitiligo and decreased serum levels of vitamin B12 (375±151 vs. 346±119 pg/ml, p=0.024), while serum levels of folate and homocysteine did not change significantly after treatment (p=0.914, p=0.127). Further studies are needed to clarify the influence of NBUVB phototherapy on folate, vitamin B12 and homocysteine levels in patients with vitiligo. Furthermore, studies with the analysis of skin levels of homocysteine rather than circulating levels may be useful to elucidate the effects of phototherapy on homocysteine levels. PMID:25941975

  16. Narrow band filter photometry of Comet Kohoutek

    NASA Technical Reports Server (NTRS)

    Angione, R. J.; Lanning, H.; Roosen, R. G.

    1975-01-01

    Narrowband photoelectric measurements of CN (3870), CO(+) (4250), C2 (4700), and C2 (5120) were made on twelve nights in December and January of Comet Kohoutek. CN and C2 appear to be stronger after perihelion, and CO(+) showed a strong post perihelion increase coincident with the first appearance of a strong gas tail and then decreased to a fairly constant level.

  17. Synchrotron studies of narrow band materials

    SciTech Connect

    Not Available

    1992-01-01

    Since last year, we have had three 3-week blocks of beamtime, in April and November 1991 and February 1992, on the Ames/Montana beamline at the Wisconsin Synchrotron Radiation Center (SRC). These runs continued our program on high temperature superconductors, heavy Fermion and related uranium and rare earth materials, and started some work on transition metal oxides. We have also had beamtime at the Brookhaven NSLS, 5 days of beamtime on the Dragon monochromator, beamline U4B, studying resonant photoemission of transition metal oxides using photon energies around the transition metal 2p edges. Data from past runs has been analyzed, and in some cases combined with photoemission and bremsstrahlung isochromat spectroscopy (BIS) data taken in the home U-M lab. 1 fig.

  18. Orbital polarization in narrow band systems

    SciTech Connect

    Eriksson, O.; Johansson, B.; Brooks, M.S..S. . Inst. of Physics; Commission of the European Communities, Karlsruhe . European Inst. for Transuranium Elements)

    1989-01-01

    A novel technique for treating orbital polarization is presented. The single electron eigenvalue shifts that emanates from the orbital polarization is of the form -E{sup 3}Lm{sub l}, where E{sup 3} is the Racah parameter, L is the orbital moment and m{sub l} the azimuthal quantum number. Thereby the effect of Hund's second rule is included not only in the total energy, but also in the eigenvalue splittings which are required in the solid. The calculations presented also incorporate the exchange and correlation potential in the local spin density approximation as well as the spin-orbit coupling. The self-consistently calculated equation-of-state for the light lanthanide Ce is presented. The observed volume collapse is well described by the parameter free calculations and accordingly the volume collapse in Ce is described as a Mott transition of the 4f electron. 20 refs., 1 fig., 1 tab.

  19. Tunable narrow band filter for CARS microscopy

    NASA Astrophysics Data System (ADS)

    Bergner, G.; Vater, E.; Akimov, D.; Schlücker, S.; Bartelt, H.; Dietzek, B.; Popp, J.

    2010-07-01

    In this letter we present an approach to CARS microscopy, which compromises between fast acquisition rates and the amount of chemical information obtained. By using a light modulator as tunable filter in concert with narrowband pump and broadband Stokes pulses, we demonstrate an experimental arrangement, which allows for fast electronic switching between CARS images recorded at different Raman resonances without the need for any optical adjustment.

  20. Mg-Al Oxides and the Remarkable Temperature Dependence of their 13 ?m and 32 ?m Emission Bands

    NASA Astrophysics Data System (ADS)

    Zeidler, S.; Mutschke, H.; Posch, Th.

    2015-08-01

    We present the temperature-dependent (10-928 K) infrared spectra of corundum and spinel, two refractory solids which occur in the stellar outflows of oxygen-rich AGB stars. From our measurements, we were able to calculate the temperature-dependent optical constants by oscillator fits. These new data are useful to further constrain the still poorly understood features of oxide dust around AGB stars, especially the 13 ?m and 32 ?m emission bands. For the latter, spinel continues to be the most promising carrier.

  1. Detection of CO Cameron band emission in comet P/Hartley 2 (1991 XV) with the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Weaver, H. A.; Feldman, P. D.; Mcphate, J. B.; A'Hearn, M. F.; Arpigny, C.; Smith, T. E.

    1994-01-01

    Ultraviolet (UV) spectra of comet P/Hartley 2 (1991 XV) taken with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) in 1991 September reveal several bands of the Cameron system of CO (a 3 Pi-X 1 Sigma). These band are most likely due to 'prompt' emission from CO2 and, thus, provide a direct tracer of the CO2 abundance in the nucleus. Photodissociative excitation of CO2 is probably the largest contributor to the Cameron band emission, but significant contributions from electron impact excitation of CO, electron impact dissociation of CO2, and dissociative recombination of CO2(+), are also possible. Using our estimate that photodissociative excitation is responsible for approximately 60% of the total excitation of the Cameron system, we derive Q(sub CO2) approximately 2.6 x 10(exp 27) molecules/s, which implies CO2/H20 approximately 4%. If all of the Cameron band emission is due to photodissociative excitation, then CO2/H2O = 7 +/- 2%. For the largest possible contributions from the other excitation mechanisms considered, the CO2 abundance could be as a small as aproximately 2-3%. We did not detect CO Fourth Positive Group emission in our data and derive an upper limit of CO/H2O less than or equal to 1% (3 sigma) for CO coming directly from the nucleus. Comparison of the relative CO2 and CO abundances in P/Hartley 2 to those in P/Halley (CO2/H2O approximately 3%-4%, CO/H20 approximately 4% for the nucleus source) indicates that selective devolatilization of the nucleus may have occurred for P/Hartley 2. A relatively large CO2/CO ratio (i.e., approximately greater than 1) seems to be a common property of cometary nuclei. Since gas phase chemistry, in either the solar nebula or the interstellar medium (ISM), appears incapable of producing large relative CO2 abundances, the CO2 in cometary nuclei is probably produced either by UV and/or cosmic ray irradiation of ISM grains prior to the formation of the Solar System, or by condensation fractionation in the solar nebula.

  2. Are the Isomers of C2H4O Responsible for the Unidentified Infrared Emission Bands and Continuum?

    NASA Astrophysics Data System (ADS)

    Bernstein, Lawrence; Lynch, D. K.

    2009-05-01

    We suggest that ethylene oxide (EO, c-C2H4O) and its isomers, acetaldehyde (AC, CH3CHO) and vinyl alcohol (VA, CH2CHOH) may be the source of the unidentified infrared bands (UIR) and their underlying continuum. Microwave transitions of all three isomers have been observed in many astronomical objects, all of which show the UIR bands. We show that the fundamental and overtone vibrational frequencies of EO correlate well with the major UIR bands at 3.3, 6.2, 7.7, 8.6, and 11.2 ?m. Two additional UIR features at 12.7 and 16.4 ?m are consistent with vibrationally excited EO, which is not collisionally quenched in space because the collision rate is negligible compared to the photon emission rate. In our mechanism, a vibrationally and rotationally cold AC molecule absorbs a 9 eV UV photon to produce vibrationally hot and rotationally cold AC in an excited electronic state. The excited AC either (1) undergoes isomerization to form vibrationally hot and rotationally cold EO in an excited electronic state, or (2) undergoes dissociation to form vibrationally and rotationally hot molecular products in excited electronic states. The electronically excited EO emits a UV photon to produce vibrationally hot and rotationally cold EO in its ground electronic state. This EO then emits its vibrational energy in the infrared (IR) and gives rise to the UIR bands. The electronically excited dissociation products also emit UV photons to produce vibrationally and rotationally hot molecules in their ground electronic states. These daughter molecules also emit in the IR and give rise to the UIR continuum. While EO and its isomers are plausible candidates for the source of the UIR spectrum, we have also found that the fundamental vibrational frequencies of cyclopropenylidene (c-C3H2) also match well with the UIR spectral bands, perhaps indicating that more than one small carbonaceous molecule (SCM) is involved.

  3. DAY-SIDE z ?-BAND EMISSION AND ECCENTRICITY OF WASP-12b

    E-print Network

    López-Morales, Mercedes

    We report the detection of the eclipse of the very hot Jupiter WASP-12b via z'-band time-series photometry obtained with the 3.5 m Astrophysical Research Consortium telescope at Apache Point Observatory. We measure a ...

  4. Spectral modification of the laser emission of a terahertz quantum cascade laser induced by broad-band double pulse injection seeding

    NASA Astrophysics Data System (ADS)

    Markmann, Sergej; Nong, Hanond; Pal, Shovon; Hekmat, Negar; Scholz, Sven; Kukharchyk, Nadezhda; Ludwig, Arne; Dhillon, Sukhdeep; Tignon, Jérôme; Marcadet, Xavier; Bock, Claudia; Kunze, Ulrich; Wieck, Andreas D.; Jukam, Nathan

    2015-09-01

    We demonstrate by injection seeding that the spectral emission of a terahertz (THz) quantum cascade laser (QCL) can be modified with broad-band THz pulses whose bandwidths are greater than the QCL bandwidth. Two broad-band THz pulses delayed in time imprint a modulation on the single THz pulse spectrum. The resulting spectrum is used to injection seed the THz QCL. By varying the time delay between the THz pulses, the amplitude distribution of the QCL longitudinal modes is modified. By applying this approach, the QCL emission is reversibly switched from multi-mode to single mode emission.

  5. Temporal behavior of the SO 1.707 micron ro-vibronic emission band in Io's atmosphere

    E-print Network

    Conor Laver; Imke de Pater; Henry Roe; Darrell Strobel

    2007-02-28

    We report observations of the ro-vibronic transition of SO at 1.707 microns on Io. These data were taken while Io was eclipsed by Jupiter, on four nights between July 2000 and March 2003. We analyze these results in conjunction with a previously published night to investigate the temporal behavior of these emissions. The observations were all conducted using the near-infrared spectrometer NIRSPEC on the W.M. Keck II telescope. The integrated emitted intensity for this band varies from 0.8 x 10^27 to 2.4 x 10^27 photons/sec, with a possible link to variations in Loki's infrared brightness. The band-shapes imply rotational temperatures of 550-1000K for the emitting gas, lending further evidence to a volcanic origin for sulfur monoxide. An attempt to detect the ro-vibronic transition of SO at 0.97 microns was unsuccessful; simultaneous detection with the 1.707 micron band would permit determination of the SO column abundance.

  6. Space Telescope and Optical Reverberation Mapping Project. III. Optical Continuum Emission and Broad-Band Time Delays in NGC 5548

    E-print Network

    Fausnaugh, M M; Barth, A J; Bentz, M C; Bottorff, M C; Carini, M T; Croxall, K V; De Rosa, G; Goad, M R; Horne, Keith; Joner, M D; Kaspi, S; Kim, M; Klimanov, S A; Kochanek, C S; Leonard, D C; Netzer, H; Peterson, B M; Schnulle, K; Sergeev, S G; Vestergaard, M; Zheng, W -K; Anderson, M D; Arevalo, P; Bazhaw, C; Borman, G A; Boroson, T A; Brandt, W N; Breeveld, A A; Brewer, B J; Cackett, E M; Crenshaw, D M; Bonta, E Dalla; De Lorenzo-Caceres, A; Dietrich, M; Edelson, R; Efimova, N V; Ely, J; Evans, P A; Filippenko, A V; Flatland, K; Gehrels, N; Geier, S; Gelbord, J M; Gonzalez, L; Gorjian, V; Grier, C J; Grupe, D; Hall, P B; Hicks, S; Horenstein, D; Hutchison, T; Im, M; Jensen, J J; Jones, J; Kaastra, J; Kelly, B C; Kennea, J A; Kim, S C; Korista, K T; Kriss, G A; Larionov, V M; Lee, J C; Lira, P; MacInnis, F; Manne-Nicholas, E R; Mathur, S; McHardy, I M; Montouri, C; Musso, R; Nazarov, S V; Norris, R P; Nousek, J A; Okhmat, D N; Pancoast, A; Papadakis, I; Parks, J R; Pei, L; Pogge, R W; Pott, J -U; Rafter, S E; Rix, H -W; Saylor, D A; Schimoia, J S; Siegel, M; Spencer, M; Starkey, D; Sung, H -I; Teems, K G; Treu, T; Turner, C S; Uttley, P; Villforth, C; Weiss, Y; Woo, J -H; Yan, H; Young, S; Zu, Y

    2015-01-01

    We present ground-based optical photometric monitoring data for NGC 5548, part of an extended multi-wavelength reverberation mapping campaign. The light curves have nearly daily cadence from 2014 January to July in nine filters ($BVRI$ and $ugriz$). Combined with UV data from the $Hubble$ $Space$ $Telescope$ and $Swift$, we confirm significant time delays between the continuum bands as a function of wavelength, extending the wavelength coverage from $1158\\,{\\rm \\AA}$ to the $z$-band ($\\sim\\! 9160\\,{\\rm \\AA}$). We find that the lags at wavelengths longer than the $V$ band are equal to or greater than the lags of high ionization-state emission lines (such as HeII$\\lambda 1640$ and $\\lambda 4686$), suggesting that the continuum emitting source is of a physical size comparable to the inner broad line region. The trend of lag with wavelength is broadly consistent with the prediction for continuum reprocessing by an accretion disk with $\\tau \\propto \\lambda^{4/3}$. However, the lags also imply a disk radius that is...

  7. High Resolution Emission Spectroscopy of the Vibration-Rotation Bands of Hbo and Hbs.

    NASA Astrophysics Data System (ADS)

    Li, G.; Ram, R. S.; Hargreaves, R. J.; Bernath, P. F.; Li, H.

    2012-06-01

    The vibration-rotation spectra of HBO and HBS have been investigated at high resolution using a Fourier transform spectrometer. The HBO molecules were produced in a high temperature furnace from the reaction of H2O vapor with boron by heating a mixture of crystalline boron and boron oxide (B2O3) at a temperature ˜1350°C. The spectra were recorded in the 1100-2200 cm-1 and 1700-4000 cm-1 wavenumber regions covering the ?3 and ?1 fundamentals, respectively. In total 24 vibrational bands involving 30 vibrational levels of H11BO and 12 bands involving 18 levels of H10BO have been rotationally analyzed. After combining the existing microwave and infrared measurements, the absolute term values have been determined for a number of vibrationally-excited states of H11BO and H10BO. The HBS molecules were formed by the reaction of CS2 and water vapor with crystalline boron at a temperature ˜1300°C. The spectra were recorded in the 850-1500 cm-1 and 1750-4000 cm-1 wavenumber regions covering the ?3 and ?1 frequency regions. In total 29 vibrational bands involving 33 vibrationally-excited levels of H11BS and 9 bands involving 12 vibrational levels of H10BS have been analyzed. The fitted spectroscopic parameters agree very well with the results of our {ab initio} calculations. {L}-resonance interactions observed between the 0200 (?) and 0220 (?) levels of HBO and HBS were analyzed using a 2×2 matrix to yield deperturbed constants.

  8. Soil moisture, dielectric permittivity and emissivity of soil: effective depth of emission measured by the L-band radiometer ELBARA

    NASA Astrophysics Data System (ADS)

    Usowicz, Boguslaw; Lukowski, Mateusz; Marczewski, Wojciech; Usowicz, Jerzy; Lipiec, Jerzy; Rojek, Edyta; Slominska, Ewa; Slominski, Jan

    2014-05-01

    Due to the large variation of soil moisture in space and in time, obtaining soil water balance with an aid of data acquired from the surface is still a challenge. Microwave remote sensing is widely used to determine the water content in soil. It is based on the fact that the dielectric constant of the soil is strongly dependent on its water content. This method provides the data in both local and global scales. Very important issue that is still not solved, is the soil depth at which radiometer "sees" the incoming radiation and how this "depth of view" depends on water content and physical properties of soil. The microwave emission comes from its entire profile, but much of this energy is absorbed by the upper layers of soil. As a result, the contribution of each layer to radiation visible for radiometer decreases with depth. The thickness of the surface layer, which significantly contributes to the energy measured by the radiometer is defined as the "penetration depth". In order to improve the physical base of the methodology of soil moisture measurements using microwave remote sensing and to determine the effective emission depth seen by the radiometer, a new algorithm was developed. This algorithm determines the reflectance coefficient from Fresnel equations, and, what is new, the complex dielectric constant of the soil, calculated from the Usowicz's statistical-physical model (S-PM) of dielectric permittivity and conductivity of soil. The model is expressed in terms of electrical resistance and capacity. The unit volume of soil in the model consists of solid, water and air, and is treated as a system made up of spheres, filling volume by overlapping layers. It was assumed that connections between layers and spheres in the layer are represented by serial and parallel connections of "resistors" and "capacitors". The emissivity of the soil surface is calculated from the ratio between the brightness temperature measured by the ELBARA radiometer (GAMMA Remote Sensing AG) and the physical temperature of the soil surface measured by infrared sensor. As the input data for S-PM: volumes of soil components, mineralogical composition, organic matter content, specific surface area and bulk density of the soil were used. Water contents in the model are iteratively changed, until emissivities calculated from the S-PM reach the best agreement with emissivities measured by the radiometer. Final water content will correspond to the soil moisture measured by the radiometer. Then, the examined soil profile will be virtually divided into thin slices where moisture, temperature and thermal properties will be measured and simultaneously modelled via S-PM. In the next step, the slices will be "added" starting from top (soil surface), until the effective soil moisture will be equal to the soil moisture measured by ELBARA. The thickness of obtained stack will be equal to desired "penetration depth". Moreover, it will be verified further by measuring the moisture content using thermal inertia. The work was partially funded by the Government of Poland through an ESA Contract under the PECS ELBARA_PD project No. 4000107897/13/NL/KML.

  9. Narrow-band imaging and white-light endoscopy with optical magnification in the diagnosis of dysplasia in Barrett’s esophagus: results of the Asia-Pacific Barrett’s Consortium

    PubMed Central

    Singh, Rajvinder; Jayanna, Mahesh; Wong, Jennie; Lim, Lee Guan; Zhang, Jun; Lv, Jing; Liu, Dong; Lee, Yi-Chia; Han, Ming-Lun; Tseng, Ping-Huei; Namasivayam, Vikneswaran; Banerjee, Rupa; Uedo, Noriya; Chan, Wah Kheong; Ho, Shiaw Hooi; Chen, Shi-yao; Bhatia, Shobna; Funasaka, Kohei; Ando, Takafumi; Wu, Justin; Lesmana, Cosmas; Tam, William; Wang, Wen-Lun; Chang, Chi-Yang; Jung, Hwoon-Yong; Jung, Kee Wook; Bestari, Muhammad Begawan; Yao, Kenshi; Chong, Vui Heng; Sharma, Prateek; Ho, Khek-Yu

    2015-01-01

    Objective: The advent and utility of new endoscopic imaging modalities for predicting the histology of Barrett’s esophagus (BE) in real time with high accuracy appear promising and could potentially obviate the need to perform random biopsies where guidelines are poorly adhered to. We embarked on evaluating the performance characteristics of white-light endoscopy with magnification (WLE-z), narrow-band imaging with magnification (NBI-z) and a combination of both modalities. Design: This was a prospective online study with 28 endoscopists from 11 countries (Asia-Pacific region) participating as assessors. In total, 35 patients with BE were assessed using 150 slides from WLE-z and NBI-z randomly arranged using a simple classification with corresponding histology. The overall Accuracy (Acc), Sensitivity (Sn), Specificity (Sp), Positive Predictive Value (PPV), and Negative Predictive Value (NPV) of WLE-z, NBI-z and a combination of both were calculated. Results: The overall Acc for WLE-z and NBI-z images was 87.1?% and 88.7?%, respectively. When images from the two modalities were placed side by side, the Acc increased to 90.3?%. The Sn, Sp, PPV, and NPV of WLE-z were 48?%, 92?%, 45?%, and 93?% while with NBI-z, these improved to 89?%, 89?%, 56?%, and 98?%, respectively. When both imaging modalities were viewed together, they improved further to 93?%, 90?%, 61?%, and 99?%. Conclusion: The high NPV (99?%) when both WLE-z and NBI-z were used simultaneously indicates that areas with regular appearance that are diagnosed with confidence can effectively be left alone and not biopsied when performed at a skilled resourced center. This approach could potentially lead to a paradigm shift of how patients with BE are assessed. PMID:26134765

  10. Molecular emission bands in the ultraviolet spectrum of the red rectangle star HD 44179

    NASA Technical Reports Server (NTRS)

    Sitko, M. L.

    1981-01-01

    New observations of the ultraviolet spectrum of HD 44179 are reported. Absorption due to the CO molecule is present in the spectrum with NCO approximately 10 to the 18th power per sq cm. Emission due to either CO or a molecule containing C=C, C=N, C-C, and C-H bonds (or both) is also present.

  11. Mapping H-band Scattered Light Emission in the Mysterious SR21Transitional Disk

    NASA Technical Reports Server (NTRS)

    Follette, Katherine B.; Motohide, Tamura; Hashimoto, Jun; Whitney, Barbara; Grady, Carol; Close, Laird; Andrews, Sean M.; Kwon, Jungmi; Wisniewski, John; Brandt, Timothy D.; Mayama, Satoshi; Kandori, Ryo; Dong, Ruobing; Abe, Lyu; Brandner, Wolfgang; Carson, Joseph; Currie, Thayne; Egner, Sebastian E.; Feldt, Markus; Goto, Miwa; Guyon, Olivier.; Hayano, Yutaka; McElwain, Michael W.; Hayashi, Masahiko; Hayashi, Saeko

    2013-01-01

    We present the first near infrared (NIR) spatially resolved images of the circumstellar transitional disk around SR21. These images were obtained with the Subaru HiCIAO camera, adaptive optics, and the polarized differential imaging technique. We resolve the disk in scattered light at H-band for stellocentric 0.1 < or approx. r < or approx. 0.6 (12 < or approx. r < or approx. 75AU). We compare our results with previously published spatially resolved 880 micron continuum Submillimeter Array images that show an inner r < or approx. 36AU cavity in SR21. Radiative transfer models reveal that the large disk depletion factor invoked to explain SR21's sub-mm cavity cannot be "universal" for all grain sizes. Even significantly more moderate depletions (delta = 0.1, 0.01 relative to an undepleted disk) than those that reproduce the sub-mm cavity (delta approx. 10(exp -6) are inconsistent with our H-band images when they are assumed to carry over to small grains, suggesting that surface grains scattering in the NIR either survive or are generated by whatever mechanism is clearing the disk midplane. In fact, the radial polarized intensity profile of our H-band observations is smooth and steeply inwardly-increasing (r(sup -3), with no evidence of a break at the 36AU sub-mm cavity wall. We hypothesize that this profile is dominated by an optically thin disk envelope or atmosphere component.We also discuss the compatibility of our data with the previously postulated existence of a sub-stellar companion to SR21 at r approx. 10-20AU, and find that we can neither exclude nor verify this scenario. This study demonstrates the power of multiwavelength imaging of transitional disks to inform modeling efforts, including the debate over precisely what physical mechanism is responsible for clearing these disks of their large midplane grains.

  12. MAPPING H-BAND SCATTERED LIGHT EMISSION IN THE MYSTERIOUS SR21 TRANSITIONAL DISK

    SciTech Connect

    Follette, Katherine B.; Close, Laird; Tamura, Motohide; Hashimoto, Jun; Kwon, Jungmi; Kandori, Ryo; Whitney, Barbara; Grady, Carol; Andrews, Sean M.; Wisniewski, John; Brandt, Timothy D.; Dong, Ruobing; Mayama, Satoshi; Abe, Lyu; Brandner, Wolfgang; Feldt, Markus; Carson, Joseph; Currie, Thayne; Egner, Sebastian E.; Goto, Miwa; and others

    2013-04-10

    We present the first near infrared (NIR) spatially resolved images of the circumstellar transitional disk around SR21. These images were obtained with the Subaru HiCIAO camera, adaptive optics, and the polarized differential imaging technique. We resolve the disk in scattered light at H-band for stellocentric 0.''1 {<=} r {<=} 0.''6 (12 {approx}< r {approx}< 75 AU). We compare our results with previously published spatially resolved 880 {mu}m continuum Submillimeter Array images that show an inner r {approx}< 36 AU cavity in SR21. Radiative transfer models reveal that the large disk depletion factor invoked to explain SR21's sub-mm cavity cannot be 'universal' for all grain sizes. Even significantly more moderate depletions ({delta} = 0.1, 0.01 relative to an undepleted disk) than those that reproduce the sub-mm cavity ({delta} {approx} 10{sup -6}) are inconsistent with our H-band images when they are assumed to carry over to small grains, suggesting that surface grains scattering in the NIR either survive or are generated by whatever mechanism is clearing the disk midplane. In fact, the radial polarized intensity profile of our H-band observations is smooth and steeply inwardly-increasing (r {sup -3}), with no evidence of a break at the 36 AU sub-mm cavity wall. We hypothesize that this profile is dominated by an optically thin disk envelope or atmosphere component. We also discuss the compatibility of our data with the previously postulated existence of a sub-stellar companion to SR21 at r {approx} 10-20 AU, and find that we can neither exclude nor verify this scenario. This study demonstrates the power of multiwavelength imaging of transitional disks to inform modeling efforts, including the debate over precisely what physical mechanism is responsible for clearing these disks of their large midplane grains.

  13. Extreme Emission Line Galaxies in CANDELS: Broad-Band Selected, Star-Bursting Dwarf Galaxies at Z greater than 1

    NASA Technical Reports Server (NTRS)

    vanderWel, A.; Straughn, A. N.; Rix, H.-W.; Finkelstein, S. L.; Koekemoer, A. M.; Weiner, B. J.; Wuyts, S.; Bell, E. F.; Faber, S. M.; Trump, J. R.; Koo, D. C.; Ferguson, H. C.; Scarlata, C.; Hathi, N. P.; Dunlop, J. S.; Newman, J. A.; Dickinson, M.; Jahnke, K.; Salmon, B. W.; deMello, D. F.; Kkocevski, D. D.; Lai, K.; Grogin, N. A.; Rodney, S. A.; Guo, Yicheng

    2012-01-01

    We identify an abundant population of extreme emission line galaxies (EELGs) at redshift z approx. 1.7 in the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) imaging from Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3). 69 EELG candidates are selected by the large contribution of exceptionally bright emission lines to their near-infrared broad-band magnitudes. Supported by spectroscopic confirmation of strong [OIII] emission lines . with rest-frame equivalent widths approx. 1000A in the four candidates that have HST/WFC3 grism observations, we conclude that these objects are galaxies with approx.10(exp 8) Solar Mass in stellar mass, undergoing an enormous starburst phase with M*/M* of only approx. 15 Myr. These bursts may cause outflows that are strong enough to produce cored dark matter profiles in low-mass galaxies. The individual star formation rates and the co-moving number density (3.7x10(exp -4) Mpc(sup -3) can produce in approx.4 Gyr much of the stellar mass density that is presently contained in 10(exp 8) - 10(exp 9) Solar Mass dwarf galaxies. Therefore, our observations provide a strong indication that many or even most of the stars in present-day dwarf galaxies formed in strong, short-lived bursts, mostly at z > 1.

  14. The population of deformed bands in $^{48}$Cr by emission of $^{8}$Be from the $^{32}$S + $^{24}$Mg reaction

    E-print Network

    S. Thummerer; W. von Oertzen; B. Gebauer; S. M. Lenzi; A. Gadea; D. R. Napoli; C. Beck; M. Rousseau

    2001-03-30

    Using particle-$\\gamma$ coincidences we have studied the population of final states after the emission of 2 $\\alpha$-particles and of $^{8}$Be in nuclei formed in $^{32}$S+$^{24}$Mg reactions at an energy of $\\textrm{E}_{\\rm L}(^{32}\\textrm{S}) = 130 {\\rm MeV}$. The data were obtained in a setup consisting of the GASP $\\gamma$-ray detection array and the multidetector array ISIS. Particle identification is obtained from the $\\Delta$E and E signals of the ISIS silicon detector telescopes, the $^{8}$Be being identified by the instantaneous pile up of the $\\Delta$E and E pulses. $\\gamma$-ray decays of the $^{48}$Cr nucleus are identified with coincidences set on 2 $\\alpha$-particles and on $^{8}$Be. Some transitions of the side-band with $K^\\pi=4^{-}$ show stronger population for $^{8}$Be emission relative to that of 2 $\\alpha$-particles (by a factor $1.5-1.8$). This observation is interpreted as due to an enhanced emission of $^{8}$Be into a more deformed nucleus. Calculations based on the extended Hauser-Feshbach compound decay formalism confirm this observation quantitatively.

  15. Extreme Emission Line Galaxies in CANDELS: Broad-Band Selected, Star-Bursting Dwarf Galaxies at Z greater than 1

    NASA Technical Reports Server (NTRS)

    VanDerWel, A.; Straughn, A. N.; Rix, H.-W.; Finkelstein, S. L.; Koekemoer, A. M.; Weiner, B. J.; Wuyts, S.; Bell, E. F.; Faber, S. M.; Trump, J. R.; Koo, D.; Ferguson, H. C.; Scarlata, C.; Hathi, N. P.; Dunlop, J. S.; Newman, J. A.; Kocevski, D. D.; Lai, K.; Grogin, N. A.; Rodney, S. A.; Lee, K.-S.; Guo, Y.

    2011-01-01

    We identify an abundant population of extreme emission line galaxies at redshift z=1.6 - 1.8 in the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) imaging from Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3). 69 candidates are selected by the large contribution of exceptionally bright emission lines to their near-infrared, broad-band fluxes. Supported by spectroscopic confirmation of strong [OIII] emission lines - with equivalent widths approximately 1000A - in the four candidates that have HST/WFC3 grism observations, we conclude that these objects are dwarf galaxies with approximately 10(exp 8) solar mass in stellar mass, undergoing an enormous star-burst phase with M*/M* of only approximately 10 Myr. The star formation activity and the co-moving number density (3.7 x 10(exp -4) Mpc(exp -3)) imply that strong, short-lived bursts play a significant, perhaps even dominant role in the formation and evolution of dwarf galaxies at z greater than 1. The observed star formation activity can produce in less than 5 Gyr the same amount of stellar mass density as is presently contained in dwarf galaxies. Therefore, our observations provide a strong indication that the stellar populations of present-day dwarf galaxies formed mainly in strong, short-lived bursts, mostly at z greater than 1.

  16. The population of deformed bands in 48Cr by emission of 8Be from the 32S + 24Mg reaction

    NASA Astrophysics Data System (ADS)

    Thummerer, S.; von Oertzen, W.; Gebauer, B.; Lenzi, S. M.; Gadea, A.; Napoli, D. R.; Beck, C.; Rousseau, M.

    2001-07-01

    Using particle-? coincidences we have studied the population of final states after the emission of two ?-particles and of 8Be in nuclei formed in 32S + 24Mg reactions at an energy of EL(32S) = 130 MeV. The data were obtained in a set-up consisting of the GASP ?-ray detection array and the multidetector array ISIS. Particle identification is obtained from the ?E and E signals of the ISIS silicon detector telescopes, with the 8Be being identified by the instantaneous `pile up' of the ?E and E pulses. ?-ray decays of the 48Cr nucleus are identified with coincidences set on two ?-particles and on 8Be. Some transitions of the side-band with K? = 4- show a stronger population for 8Be emission relative to that of two ?-particles (by a factor of 1.5-1.8). This observation is interpreted as being due to enhanced emission of 8Be into a more deformed nucleus. Calculations based on the extended Hauser-Feshbach compound decay formalism confirm this observation quantitatively.

  17. Theoretical predictions for the effect of nebular emission on the broad-band photometry of high-redshift galaxies

    NASA Astrophysics Data System (ADS)

    Wilkins, Stephen M.; Coulton, William; Caruana, Joseph; Croft, Rupert; Matteo, Tiziana Di; Khandai, Nishikanta; Feng, Yu; Bunker, Andrew; Elbert, Holly

    2013-11-01

    By combining optical and near-IR observations from the Hubble Space Telescope with near-IR photometry from the Spitzer Space Telescope, it is possible to measure the rest-frame UV-optical colours of galaxies at z = 4-8. The UV-optical spectral energy distribution of star formation dominated galaxies is the result of several different factors. These include the joint distribution of stellar masses, ages and metallicities (solely responsible for the pure stellar spectral energy distribution), and the subsequent reprocessing by dust and gas in the interstellar medium. Using a large cosmological hydrodynamical simulation (MassiveBlack-II), we investigate the predicted spectral energy distributions of galaxies at high redshift with a particular emphasis on assessing the potential contribution of nebular emission. We find that the average (median) pure stellar UV-optical colour correlates with both luminosity and redshift such that galaxies at lower redshift and higher luminosity are typically redder. Assuming that the escape fraction of ionizing photons is close to zero, the effect of nebular emission is to redden the UV-optical 1500 - Vw colour by, on average, 0.4 mag at z = 8 declining to 0.25 mag at z = 4. Young and low-metallicity stellar populations, which typically have bluer pure stellar UV-optical colours, produce larger ionizing luminosities and are thus more strongly affected by the reddening effects of nebular emission. This causes the distribution of 1500 - Vw colours to narrow and the trends with luminosity and redshift to weaken. The strong effect of nebular emission leaves observed-frame colours critically sensitive to the redshift of the source. For example, increasing the redshift by 0.1 can result in observed-frame colours changing by up to ˜0.6. These predictions reinforce the need to include nebular emission when modelling the spectral energy distributions of galaxies at high redshift and also highlight the difficultly in interpreting the observed colours of individual galaxies without precise redshift information.

  18. Stimulated emission within the exciplex band by plasmonic-nanostructured polymeric heterojunctions

    NASA Astrophysics Data System (ADS)

    Zhang, Xinping; Li, Hongwei; Wang, Yimeng; Liu, Feifei

    2015-03-01

    Organic heterojunctions have been extensively employed in the design of light-emitting diodes, photovoltaic devices, and thin-film field-effect transistors, which can be achieved by constructing a bilayer or a multi-layered thin-film deposition, or by blending two or more organic semiconductors with different charge-transport performances. Charge transfer excited states or exciplex may form on the heterointerfaces. Efficient light-emitting diodes have been demonstrated using exciplex emission. However, lasing or stimulated emission processes have not been observed with exciplex formation at organic heterojunctions. In this work, we demonstrate strong coherent interaction between photons and exciplex formation in the blends of poly-9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-l,4-phenylenediamine (PFB) and poly-9,9'-dioctylfluorene-co-benzothiadiazole (F8BT), leading to transient stimulated exciplex emission. The responsible mechanisms involve plasmonic local-field enhancement and plasmonic feedback in a three-dimensional gold-nanoparticle matrix.Organic heterojunctions have been extensively employed in the design of light-emitting diodes, photovoltaic devices, and thin-film field-effect transistors, which can be achieved by constructing a bilayer or a multi-layered thin-film deposition, or by blending two or more organic semiconductors with different charge-transport performances. Charge transfer excited states or exciplex may form on the heterointerfaces. Efficient light-emitting diodes have been demonstrated using exciplex emission. However, lasing or stimulated emission processes have not been observed with exciplex formation at organic heterojunctions. In this work, we demonstrate strong coherent interaction between photons and exciplex formation in the blends of poly-9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-l,4-phenylenediamine (PFB) and poly-9,9'-dioctylfluorene-co-benzothiadiazole (F8BT), leading to transient stimulated exciplex emission. The responsible mechanisms involve plasmonic local-field enhancement and plasmonic feedback in a three-dimensional gold-nanoparticle matrix. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00140d

  19. Blue Luminescence and Extended Red Emission: Possible Connections to the Diffuse Interstellar Bands

    NASA Astrophysics Data System (ADS)

    Witt, A. N.

    2014-02-01

    Blue luminescence (BL) and extended red emission (ERE) are observed as diffuse, optical-wavelength emissions in interstellar space, resulting from photoluminescence by ultraviolet(UV)-illuminated interstellar grains. Faintness and the challenge of separating the BL and ERE from the frequently much brighter dust-scattered continuum present major observational hurdles, which have permitted only slow progress in testing the numerous models that have been advanced to explain these two phenomena. Both the ERE, peaking near 680 nm (FWHM ~ 60 - 120 nm) and the BL, asymmetrically peaking at ~ 378 nm (FWHM ~ 45 nm), were first discovered in the Red Rectangle nebula. Subsequently, ERE and BL have been observed in other reflection nebulae, and in the case of the ERE, in carbon-rich planetary nebulae, H II regions, high-latitude cirrus clouds, the galactic diffuse ISM, and in external galaxies. BL exhibits a close spatial and intensity correlation with emission in the aromatic emission feature at 3.3 micron, most likely arising from small, neutral polycyclic aromatic hydrocarbon (PAH) molecules. The spectral characteristics of the BL also agree with those of fluorescence by PAH molecules with 13 to 19 carbon atoms. The BL phenomenon is thus most readily understood as the optical fluorescence of small, UV-excited aromatic molecules. The ERE, by contrast, though co-existent with mid-IR PAH emissions, does not correlate with emissions from either neutral or ionized PAHs. Instead, the spatial ERE morphology appears to be strictly governed by the density of far-UV (E >= 10.5 eV) photons, which are required for the ERE excitation. The most restrictive observational constraint for the ERE process is its exceptionally high quantum efficiency. If the ERE results from photo-excitation of a nano-particle carrier by photons with E >= 10.5 eV in a single-step process, the quantum efficiency exceeds 100%. Such a process, in which one to three low-energy optical photons may be emitted following a single far-UV excitation, is possible in highly isolated small clusters, e.g. small, dehydrogenated carbon clusters with about 20 to 28 carbon atoms. A possible connection between the ERE carriers and the carriers of DIBs may exist in that both are ubiquitous throughout the diffuse interstellar medium and both have an abundance of low-lying electronic levels with E <= 2.3 eV above the ground state.

  20. The electrosphere of macroscopc ""nuclei"": diffuse emissions in the MeV band from dark antimatter

    SciTech Connect

    Forbes, Michael Mcneil; Lawson, Kyle; Zhitnitsky, Ariel R

    2009-01-01

    Using a Thomas-Fermi model, we calculate the structure of the electrosphere of the quark antimatter nuggets postulated to comprise much of the dark matter. This provides a single self-consistent density profile from ultra-rel ativistic densities to the non-relativistic Boltzmann regime. We use this to present a microscopically justified calculation of several properties of the nuggets, including their net charge, and the ratio of MeV to 511 keV emissions from electron annihilation. We find that the calculated parameters agree with previous phenomenological estimates based on the observational supposition that the nuggets are a source of several unexplained diffuse emissions from the galaxy. This provides another nontrivial verification of the dark matter proposal. The structure of the electrosphere is quite general and will also be valid at the surface of strange-quark stars, should they exist.

  1. Spatial variation of the 3.29 and 3.40 micron emission bands within reflection nebulae and the photochemical evolution of methylated polycyclic aromatic hydrocarbons.

    PubMed

    Joblin, C; Tielens, A G; Allamandola, L J; Geballe, T R

    1996-02-20

    Spectra of 3 micrometers emission features have been obtained at several positions within the reflection nebulae NGC 1333 SVS3 and NGC 2023. Strong variations of the relative intensities of the 3.29 micrometers feature and its most prominent satellite band at 3.40 micrometers are found. It is shown that (i) the 3.40 micrometers band is too intense with respect to the 3.29 micrometers band at certain positions to arise from hot band emission alone, (ii) the 3.40 micrometers band can be reasonably well matched by new laboratory spectra of gas-phase polycyclic aromatic hydrocarbons (PAHs) with alkyl (-CH3) side groups, and (iii) the variations in the 3.40 micrometers to 3.29 micrometers band intensity ratios are consistent with the photochemical erosion of alkylated PAHs. We conclude that the 3.40 micrometers emission feature is attributable to -CH3 side groups on PAH molecules. We predict a value of 0.5 for the peak intensity ratio of the 3.40 and 3.29 micrometers emission bands from free PAHs in the diffuse interstellar medium, which would correspond to a proportion of one methyl group for four peripheral hydrogens. We also compare the 3 micrometers spectrum of the proto-planetary nebula IRAS 05341+0852 with the spectrum of the planetary nebula IRAS 21282+5050. We suggest that a photochemical evolution of the initial aliphatic and aromatic hydrocarbon mixture formed in the outflow is responsible for the changes observed in the 3 micrometers emission spectra of these objects. PMID:11538557

  2. Revealing the surface origin of green band emission from ZnO nanostructures by plasma immersion ion implantation induced quenching

    SciTech Connect

    Yang, Y.; Sun, X. W.; Tay, B. K.; Cao, Peter H. T.; Wang, J. X.; Zhang, X. H.

    2008-03-15

    Surface defect passivation for ZnO nanocombs (NCBs), random nanowires (RNWs), and aligned nanowires (ANWs) was performed through a metal plasma immersion ion implantation with low bias voltages ranging from 0 to 10 kV, where Ni was used as the modification ion. The depth of surface-originated green band (GB) emission is thus probed, revealing the surface origin of the GB. It is also found that the GB is closely related to oxygen gas content during growth of the nanostructures. The GB origin of NCBs and RNWs grown with higher oxygen content is shallower ({approx}0.5 nm), which can be completely quenched with no bias applied. However, the GB origin of ANWs grown at lower oxygen content is much deeper ({approx}7 nm) with a complete quenching bias of 10 kV. Quenching of the GB can be attributed to passivation of the surface hole or electron trapping sites (oxygen vacancies) by Ni ions.

  3. Band Gap Energy of Chalcopyrite Thin Film Solar Cell Absorbers Determined by Soft X-Ray Emission and Absorption Spectroscopy

    SciTech Connect

    Bar, M.; Weinhardt, L.; Pookpanratana, S.; Heske, C.; Nishiwaki, S.; Shafarman, W.; Fuchs, O.; Blum, M.; Yang, W.; Denlinger, J.D.

    2008-05-11

    The chemical and electronic structure of high efficiency chalcopyrite thin film solar cell absorbers significantly differs between the surface and the bulk. While it is widely accepted that the absorber surface exhibits a Cu-poor surface phase with increased band gap (Eg), a direct access to the crucial information of the depth-dependency of Eg is still missing. In this paper, we demonstrate that a combination of x-ray emission and absorption spectroscopy allows a determination of Eg in the surface-near bulk and thus complements the established surface- and bulk-sensitive techniques of Eg determination. As an example, we discuss the determination of Eg for a Cu(In,Ga)Se2 absorber [(1.52 +- 0.20) eV].

  4. Spontaneous emission from a two-level atom in anisotropic one-band photonic crystals: A fractional calculus approach

    SciTech Connect

    Wu, J.-N.; Huang, C.-H.; Cheng, S.-C.; Hsieh, W.-F.

    2010-02-15

    Spontaneous emission (SE) from a two-level atom in an anisotropic photonic crystal (PC) is investigated by the fractional calculus. Physical phenomena of the SE are studied analytically by solving the fractional kinetic equations of the SE. There is a dynamical discrepancy between the SE of anisotropic and isotropic PCs. We find that, contrary to the SE phenomenon of the isotropic PC, the SE near the band edge of an anisotropic PC shows no photon-atom bound state. It is consistent with the experimental results of Barth, Schuster, Gruber, and Cichos [Phys. Rev. Lett. 96, 243902 (2006)] that the anisotropic property of the system enhances the SE. We also study effects of dispersion curvatures on the changes of the photonic density of states and the appearance of the diffusion fields in the SE.

  5. Search for CO2/CO Band Emission in Active Asteroid 324P

    NASA Astrophysics Data System (ADS)

    Mommert, Michael; Hora, Joseph L.; Hsieh, Henry H.; Trilling, David E.; Sheppard, Scott S.

    2015-10-01

    Until a few decades ago, the distinction between asteroids and comets seemed to be simple: comets exhibit activity in the form of a coma and/or a tail as a result of the sublimation of surface ices, whereas asteroids are inactive, rocky bodies. The separation between the two groups became less clear with the discovery of asteroidal bodies that exhibit comet-like dust activity - the active asteroids. For some of those objects, disruption or mass loss due to rotational destabilization or recent collisions are the most likely processes causing the activity. Other objects display recurrent dust activity near perihelion that seems to be caused by the sublimation of ices, but gases have never been directly measured in them. We propose the first Spitzer observations of recurrently active asteroid 324P to search for emission from CO2 or CO. Our observations will detect emission from either gas with unprecedented sensitivity and provide the first ever confirmed detection of volatiles in an active asteroid. We will measure the CO2/CO gas production rates - or put upper-limits on them in the case of a lack of emission. The detection of sublimation-driven activity in active asteroids provide important constraints on the volatile inventory of the inner Solar System and Solar System formation models, gives insight into volatile preservation/retention in asteroidal bodies, and may be relevant to primordial terrestrial water delivery scenarios, as well as future asteroid resource utilization. This proposal conforms with the Spitzer Cycle 12 focus on planetary science programs observing targets in our Solar System.

  6. The effects of soil moisture, surface roughness, and vegetation on L-band emission and backscatter

    NASA Technical Reports Server (NTRS)

    Wang, James R.; Shiue, J. C.; Engman, Edwin T.; Schmugge, Thomas J.; Mo, Tsan

    1987-01-01

    Measurements performed with SIR-B at 1.28 GHz and an airborne multiple-beam push-broom radiometer at 1.4 GHz over agricultural fields near Fresno, California are examined. A theoretical model (Kirchhoff approximation) was used to assess the effects of surface roughness and vegetation (alfalfa and lettuce) with respect to the responses of microwave emission and backscatter to soil-moisture variations. It is found that the surface roughness plays a dominant role compared to the vegetation cover in the microwave backscatter.

  7. Broad-Band Model Spectra of Gamma-Ray Emission from Millisecond Pulsars

    E-print Network

    Tomasz Bulik; Bronislaw Rudak

    1998-10-01

    We present spectra of pulsed gamma-ray emission expected from millisecond pulsars within the framework of polar-cap models. The spectra are a superposition of three components due to curvature (CR), synchrotron (SR), and Compton upscattering (ICS) processes. The CR component dominates below $100 $GeV and the ICS component exhibits a peak at $\\sim 1 $TeV. The CR component should be observable from J0437-4715 with the next generation gamma-ray telescopes, like e.g. GLAST.

  8. WIDE-BAND SUZAKU ANALYSIS OF THE PERSISTENT EMISSION FROM SGR 0501+4516 DURING THE 2008 OUTBURST

    SciTech Connect

    Enoto, T.; Makishima, K.; Nakazawa, K.; Yamada, S.; Rea, N.; Nakagawa, Y. E.; Sakamoto, T.; Esposito, P.; Mereghetti, S.; Tiengo, A.; Goetz, D.; Israel, G. L.; Stella, L.; Kokubun, M.; Murakami, H.; Turolla, R.; Yamaoka, K.; Yoshida, A.; Zane, S.

    2010-05-20

    We observed the soft gamma repeater SGR 0501+4516 with Suzaku for {approx}51 ks on 2008 August 26-27, about 4 days after its discovery. Following the first paper, which reported on the persistent soft X-ray emission and the wide-band spectrum of an intense short burst, this paper presents an analysis of the persistent broadband (1-70 keV) spectra of this source in outburst, taken with the X-ray Imaging Spectrometer (XIS) and the Hard X-ray Detector (HXD). Pulse-phase folding in the 12-35 keV HXD-PIN data on an ephemeris based on multi-satellite timing measurements at soft X-rays revealed the pulsed signals at {approx_gt}99% confidence in the hard X-ray band. The wide-band spectrum clearly consists of a soft component and a separate hard component, crossing over at {approx}7 keV. When the soft component is modeled by a blackbody plus a Comptonized blackbody, the hard component exhibits a 20-100 keV flux of 4.8{sup +0.8}{sub -0.6}(stat.){sup +0.8}{sub -0.4}(sys.) x 10{sup -11} erg s{sup -1} cm{sup -2} and a photon index of {Gamma} = 0.79{sup +0.20}{sub -0.18}(stat.){sup +0.01}{sub -0.06}(sys.). The hard X-ray data are compared with those obtained by INTEGRAL about 1 day later. Combining the present results with those on other magnetars, we discuss a possible correlation between the spectral hardness of magnetars and their characteristic age and magnetic field strengths.

  9. Defect conduction bands, localization, and temperature-dependent electron emission from Al-Al2O3-Au diodes

    NASA Astrophysics Data System (ADS)

    Hickmott, T. W.

    2010-11-01

    The temperature dependence of several phenomena connected with voltage-controlled negative resistance (VCNR) of Al-Al2O3-Au diodes has been measured between 200 and 300 K. These include the current-voltage (I-V) characteristics, electroluminescence (EL), and electron emission into vacuum (EM) of diodes with 12-20 nm of anodic Al2O3. There is an abrupt decrease in EM by 3 orders of magnitude as temperature decreases from 285 to 280 K. EM recovers to the same magnitude as at 300 K at ˜260 K and is nearly constant between 260 and 200 K. The lower temperature at which EM recovers depends on the anodizing electrolyte. EM is decoupled from the major conduction mechanism because the voltage for maximum current of the I-V curve and the voltage threshold for EL are nearly constant over the same temperature range. A model is proposed in which defect levels of oxygen vacancies form two defect conduction bands in amorphous Al2O3. The concentration of oxygen vacancies is estimated from measurements of polarization of Al-Al2O3-Au diodes that do not break down to form VCNR in their I-V characteristics. EM at high and low temperatures is through defect conduction bands. Suppression of EM in the intermediate temperature range is due to localization of electrons caused by the irregular potential present when defect centers in the lower defect conduction band are nearly fully occupied. EM shows a temperature dependent metal-nonmetal transition while the conduction current does not.

  10. Spatially resolved band alignments at Au-hexadecanethiol monolayer-GaAs(001) interfaces by ballistic electron emission microscopy

    NASA Astrophysics Data System (ADS)

    Junay, A.; Guézo, S.; Turban, P.; Delhaye, G.; Lépine, B.; Tricot, S.; Ababou-Girard, S.; Solal, F.

    2015-08-01

    We study structural and electronic inhomogeneities in Metal—Organic Molecular monoLayer (OML)—semiconductor interfaces at the sub-nanometer scale by means of in situ Ballistic Electron Emission Microscopy (BEEM). BEEM imaging of Au/1-hexadecanethiols/GaAs(001) heterostructures reveals the evolution of pinholes density as a function of the thickness of the metallic top-contact. Using BEEM in spectroscopic mode in non-short-circuited areas, local electronic fingerprints (barrier height values and corresponding spectral weights) reveal a low-energy tunneling regime through the insulating organic monolayer. At higher energies, BEEM evidences new conduction channels, associated with hot-electron injection in the empty molecular orbitals of the OML. Corresponding band diagrams at buried interfaces can be thus locally described. The energy position of GaAs conduction band minimum in the heterostructure is observed to evolve as a function of the thickness of the deposited metal, and coherently with size-dependent electrostatic effects under the molecular patches. Such BEEM analysis provides a quantitative diagnosis on metallic top-contact formation on organic molecular monolayer and appears as a relevant characterization for its optimization.

  11. The modeling of emissions of Lyman-Birge-Hopfield and Vegard-Kaplan bands in the atmospheres of planets

    NASA Astrophysics Data System (ADS)

    Kirillov, Andrey S.

    Molecular nitrogen is main component in the atmospheres of Earth, Titan, Triton. Energetic particles interacting with the atmospheres cause electronic excitation of nitrogen molecules. Total quenching rate coefficients of three singlet and four triplet states of molecular nitrogen in the collisions with N2 and O2 molecules are calculated on the basis of quantum-chemical approximations. The calculated rate coefficients of electronic quenching of N2* molecules are compared with available experimental data. An influence of radiational and collisional processes on vibrational populations of electronically excited N2(a1) and N2(A3) molecules and emissions of Lyman-Birge-Hopfield and Vegard-Kaplan bands is studied for the mixture of N2 and O2 at different pressures. It is indicated that molecular collisions cause changes in relative populations of vibrational levels of the states and intensity relations of ultraviolet bands of N2 with the rise in the pressure and O2 admixture. The influence of electronically excited molecules on vibrational kinetics of molecular nitrogen is discussed.

  12. Monte Carlo simulations of ambient temperature uncertainty determined by dual-band pyrometry

    NASA Astrophysics Data System (ADS)

    Araújo, António; Martins, Nelson

    2015-08-01

    The Monte Carlo technique for uncertainty propagation was used to estimate the uncertainty of ambient temperature measurements, obtained by dual-band pyrometry, of assumed grey surfaces. A large number of simulations were performed for a wide range of values from the following parameters: uncertainty of the detectors, emissivity of the target surface, background temperature of the surrounding surfaces, and spectral characteristics of the detectors (bandwidth, location of the bands, and distance between bands). Temperature measurement uncertainties from single-band pyrometry were also simulated for evaluation against dual-band uncertainties. It is concluded that the following parameters minimize dual-band temperature uncertainty: narrow wavelength bands, far apart from each other, positioned towards low wavelengths; low surface emissivity; high or low background temperature with respect to the target surface temperature (uncertainty grows very fast as the background and target temperatures converge, and tends to a constant minimum value as the background and target temperatures diverge).

  13. DAY-SIDE z'-BAND EMISSION AND ECCENTRICITY OF WASP-12b

    SciTech Connect

    Lopez-Morales, Mercedes; Rogers, Justin C.; Coughlin, Jeffrey L.; Sing, David K.; Burrows, Adam; Spiegel, David S.; Apai, Daniel; Adams, Elisabeth R.

    2010-06-10

    We report the detection of the eclipse of the very hot Jupiter WASP-12b via z'-band time-series photometry obtained with the 3.5 m Astrophysical Research Consortium telescope at Apache Point Observatory. We measure a decrease in flux of 0.082% {+-} 0.015% during the passage of the planet behind the star. That planetary flux is equally well reproduced by atmospheric models with and without extra absorbers, and blackbody models with f {>=} 0.585 {+-} 0.080. It is therefore necessary to measure the planet at other wavelengths to further constrain its atmospheric properties. The eclipse appears centered at phase {phi} = 0.5100{sup +0.0072}{sub -0.0061}, consistent with an orbital eccentricity of |ecos {omega}| = 0.016{sup +0.011}{sub -0.009} (see note at the end of Section 4). If the orbit of the planet is indeed eccentric, the large radius of WASP-12b can be explained by tidal heating.

  14. Internal entrainment and the origin of jet-related broad-band emission in Centaurus A

    NASA Astrophysics Data System (ADS)

    Wykes, Sarka; Hardcastle, Martin J.; Karakas, Amanda I.; Vink, Jorick S.

    2015-02-01

    The dimensions of Fanaroff-Riley class I jets and the stellar densities at galactic centres imply that there will be numerous interactions between the jet and stellar winds. These may give rise to the observed diffuse and `knotty' structure of the jets in the X-ray, and can also mass load the jets. We performed modelling of internal entrainment from stars intercepted by Centaurus A's jet, using stellar evolution- and wind codes. From photometry and a code-synthesized population of 12 Gyr (Z = 0.004), 3 Gyr (Z = 0.008) and 0-60 Myr (Z = 0.02) stars, appropriate for the parent elliptical NGC 5128, the total number of stars in the jet is ˜8 × 108. Our model is energetically capable of producing the observed X-ray emission, even without young stars. We also reproduce the radio through X-ray spectrum of the jet, albeit in a downstream region with distinctly fewer young stars, and recover the mean X-ray spectral index. We derive an internal entrainment rate of ˜2.3 × 10-3 M? yr-1 which implies substantial jet deceleration. Our absolute nucleosynthetic yields for the Asymptotic Giant Branch stellar population in the jet show the highest amounts for 4He, 16O, 12C, 14N and 20Ne. If some of the events at ?55 EeV detected by the Pierre Auger Observatory originate from internal entrainment in Centaurus A, we predict that their composition will be largely intermediate-mass nuclei with 16O, 12C and 14N the key isotopes.

  15. Calculated Hydroxyl A(sup 2)(Sigma) leads to...X(sup 2)II (0,0) Band Emission Rate Factors Applicable to Atmospheric Spectroscopy

    NASA Technical Reports Server (NTRS)

    Cageao, R. P.; Ha, Y. L.; Jiang, Y.; Morgan, M. F.; Yung, Y. L.; Sander, S. P.

    1996-01-01

    A calculation of the A(sup 2)(Sigma) leads to...X(sup 2)II (0,0) band emission rate factors and line center absorption cross sections of OH applicable to its measurement using solar resonant flourenscence in the terrestrial atmosphere is presented in this paper.

  16. Direct band gap optical emission from compressively strained Ge films grown on relaxed Si{sub 0.5}Ge{sub 0.5} substrate

    SciTech Connect

    Aluguri, R.; Manna, S.; Ray, S. K.

    2013-10-14

    Compressively strained Ge films have been grown on relaxed Si{sub 0.5}Ge{sub 0.5} virtual substrate in ultra high vacuum using molecular beam epitaxy. Structural characterization has shown that the Ge films are compressively strained with partial strain relaxation in a film thicker than 3.0 nm, due to onset of island nucleation. Photoluminescence spectra exhibit the splitting of degenerate Ge valence band into heavy hole and light hole bands with a broad direct band gap emission peak around 0.81 eV. Temperature and excitation power dependent emission characteristics have been studied to investigate the mechanism of luminescence quenching at high temperatures and the role of non-radiative recombination centers.

  17. SDSS J083253.18+064316.7: one strange object with double-peaked narrow H? but single-peaked narrow H?

    NASA Astrophysics Data System (ADS)

    Zhang, Xue-Guang

    2015-04-01

    In this Letter, we first report one unique object SDSS J0832+0643 with particular features of narrow Balmer emission lines: double-peaked narrow H? but single-peaked narrow H?. The particular features cannot be expected by currently proposed kinematic models for double-peaked narrow emission lines, because the proposed kinematic models lead to similar line profiles of narrow Balmer emission lines. However, due to radiative transfer effects, the non-kinematic model can be naturally applied to well explain the particular features of narrow Balmer emission lines: larger optical depth in H? than 10 leads to observed double-peaked narrow H?, but smaller optical depth in H? around 2 leads to observed single-peaked narrow H?. Therefore, SDSS J0832+0643 can be used as strong evidence to support the non-kinematic model for double-peaked narrow emission lines.

  18. Observation of an Intermediate Band in Sn-doped Chalcopyrites with Wide-spectrum Solar Response

    PubMed Central

    Yang, Chongyin; Qin, Mingsheng; Wang, Yaoming; Wan, Dongyun; Huang, Fuqiang; Lin, Jianhua

    2013-01-01

    Nanostrcutured particles and polycrystalline thin films of Sn-doped chalcopyrite are synthesized by newly-developed methods. Surprisingly, Sn doping introduces a narrow partially filled intermediate band (IB) located ~1.7?eV (CuGaS2) and ~0.8?eV (CuInS2) above the valance band maximum in the forbidden band gap. Diffuse reflection spectra and photoluminescence spectra reveal extra absorption and emission spectra induced by the IBs, which are further supported by first-principle calculations. Wide spectrum solar response greatly enhances photocatalysis, photovoltaics, and photo-induced hydrogen production due to the intermediate band. PMID:23412565

  19. Recent Results from Broad-Band Intensity Mapping Measurements of Cosmic Large Scale Structure

    NASA Astrophysics Data System (ADS)

    Zemcov, Michael B.; CIBER, Herschel-SPIRE

    2016-01-01

    Intensity mapping integrates the total emission in a given spectral band over the universe's history. Tomographic measurements of cosmic structure can be performed using specific line tracers observed in narrow bands, but a wealth of information is also available from broad-band observations performed by instruments capable of capturing high-fidelity, wide-angle images of extragalactic emission. Sensitive to the continuum emission from faint and diffuse sources, these broad-band measurements provide a view on cosmic structure traced by components not readily detected in point source surveys. After accounting for measurement effects and astrophysical foregrounds, the angular power spectra of such data can be compared to predictions from models to yield powerful insights into the history of cosmic structure formation. This talk will highlight some recent measurements of large scale structure performed using broad-band intensity mapping methods that have given new insights on faint, distant, and diffuse components in the extragalactic background light.

  20. The emission and scattering of L-band microwave radiation from rough ocean surfaces and wind speed measurements from the Aquarius sensor

    NASA Astrophysics Data System (ADS)

    Meissner, Thomas; Wentz, Frank J.; Ricciardulli, Lucrezia

    2014-09-01

    In order to achieve the required accuracy in sea surface salinity (SSS) measurements from L-band radiometers such as the Aquarius/SAC-D or SMOS (Soil Moisture and Ocean Salinity) mission, it is crucial to accurately correct the radiation that is emitted from the ocean surface for roughness effects. We derive a geophysical model function (GMF) for the emission and backscatter of L-band microwave radiation from rough ocean surfaces. The analysis is based on radiometer brightness temperature and scatterometer backscatter observations both taken on board Aquarius. The data are temporally and spatially collocated with wind speeds from WindSat and F17 SSMIS (Special Sensor Microwave Imager Sounder) and wind directions from NCEP (National Center for Environmental Prediction) GDAS (Global Data Assimilation System). This GMF is the basis for retrieval of ocean surface wind speed combining L-band H-pol radiometer and HH-pol scatterometer observations. The accuracy of theses combined passive/active L-band wind speeds matches those of many other satellite microwave sensors. The L-band GMF together with the combined passive/active L-band wind speeds is utilized in the Aquarius SSS retrieval algorithm for the surface roughness correction. We demonstrate that using these L-band wind speeds instead of NCEP wind speeds leads to a significant improvement in the SSS accuracy. Further improvements in the roughness correction algorithm can be obtained by adding VV-pol scatterometer measurements and wave height (WH) data into the GMF.

  1. First detection of Mars atmospheric hydroxyl: CRISM Near-IR measurement versus LMD GCM simulation of OH Meinel band emission in the Mars polar winter atmosphere

    NASA Astrophysics Data System (ADS)

    Todd Clancy, R.; Sandor, Brad J.; García-Muñoz, Antonio; Lefèvre, Franck; Smith, Michael D.; Wolff, Michael J.; Montmessin, Franck; Murchie, Scott L.; Nair, Hari

    2013-09-01

    Visible and near-IR Meinel band emissions originate from excited OH in the terrestrial upper atmosphere (Meinel, I.A.B. [1950]. Astrophys. J. 111, 555. http://dx.doi.org/10.1086/145296), and have recently been detected in the Venus nightside upper mesosphere (Piccioni, G. et al. [2008]. Astron. Astrophys. 483, L29-L33. http://dx.doi.org/10.1051/0004-6361:200809761). Meinel band observations support key studies of transport and photochemistry in both of these atmospheres. In the case of Mars, OH regulates the basic stability of the CO2 atmosphere to photolytic decomposition (to CO and O2, e.g. Parkinson, T.D., Hunten, D.M. [1972]. J. Atmos. Sci. 29, 1380-1390. http://dx.doi.org/10.1175/1520-0469(1972)029<1380:SAAOOO>2.0.CO;2), and yet has never been measured. We present the first detection of Mars atmospheric OH, associated with CRISM near-IR spectral limb observations of polar night Meinel band emissions centered at 1.45 and 2.9 ?m. Meinel band (1-0), (2-1), and (2-0) average limb intensities of 990 ± 280, 1060 ± 480, and 200 ± 100 kiloRayleighs (kR), respectively, are determined for 70-90 NS polar winter latitudes over altitudes of 40-56 km. Additional OH bands, such as (3-2), (3-1), and (4-2), present ?1? measurements. Uncertainty in the (4-2) band emission rate contributes to increased uncertainty in the determination of the O2(1?g) (0-0)/(0-1) band emission ratio A00/A01=47-12+26. An average profile retrieval for Mars OH polar nightglow indicates 45-55 km altitude levels for volume emission rates (VER) of 0.4 (2-0) to 2 (1-0, 2-1) × 104 photons/(cm3 s). Similar to polar night O2(1?g) emission (e.g. Clancy, R.T. et al. [2012]. J. Geophys. Res. (Planets) 117, E00J10. http://dx.doi.org/10.1029/2011JE004018), Meinel OH band emission is supported by upper level, winter poleward transport of O and H in the deep Hadley solsticial circulations of Mars. The retrieved OH emission rates are compared to polar winter OH nightglow simulated by the LMD (Laboratoire de Météorologie Dynamique) photochemical GCM (global climate model), employing detailed photochemistry (e.g. Lefèvre, F., Lebonnois, S., Montmessin, F., Forget, F. [2004]. J. Geophys. Res. (Planets) 109, E07004. http://dx.doi.org/10.1029/2004JE002268) and energy transfer processes (excitation and quenching) developed for Mars Meinel OH band nightglow by García Muñoz et al. (García Muñoz, A., McConnell, J.C., McDade, I.C., Melo, S.M.L. [2005]. Icarus 176, 75-95). Modeled versus observed OH emission behavior agrees within measurement uncertainties with the assumptions of a Bates-Nicolet (H + O3) source for excited OH production, and ‘collisional-cascade’ quenching of the OH vibrational population by CO2. ‘Sudden-death’ quenching of excited OH by CO2 leads to 100× less OH emission than observed. The combined agreement between LMD GCM simulated and CRISM observed O2(1?g) and Meinel OH polar nightglow behaviors represents a significant demonstration of the LMD model capability to couple odd oxygen and hydrogen photochemistry and transport by the Mars global circulation in a realistic fashion.

  2. First detection of Mars atmospheric hydroxyl: CRISM Near-IR measurement versus LMD GCM simulation of OH Meinel band emission in the Mars polar winter atmosphere

    NASA Astrophysics Data System (ADS)

    Clancy, R. Todd; Sandor, Brad J.; García-Muñoz, Antonio; Lefèvre, Franck; Smith, Michael D.; Wolff, Michael J.; Montmessin, Franck; Murchie, Scott L.; Nair, Hari

    2013-09-01

    Visible and near-IR Meinel band emissions originate from excited OH in the terrestrial upper atmosphere (Meinel, I.A.B. [1950]. Astrophys. J. 111, 555. http://dx.doi.org/10.1086/145296), and have recently been detected in the Venus nightside upper mesosphere (Piccioni, G. et al. [2008]. Astron. Astrophys. 483, L29-L33. http://dx.doi.org/10.1051/0004-6361:200809761). Meinel band observations support key studies of transport and photochemistry in both of these atmospheres. In the case of Mars, OH regulates the basic stability of the CO2 atmosphere to photolytic decomposition (to CO and O2, e.g. Parkinson, T.D., Hunten, D.M. [1972]. J. Atmos. Sci. 29, 1380-1390. http://dx.doi.org/10.1175/1520-0469(1972)029<1380:SAAOOO>2.0.CO;2), and yet has never been measured. We present the first detection of Mars atmospheric OH, associated with CRISM near-IR spectral limb observations of polar night Meinel band emissions centered at 1.45 and 2.9 ?m. Meinel band (1-0), (2-1), and (2-0) average limb intensities of 990 ± 280, 1060 ± 480, and 200 ± 100 kiloRayleighs (kR), respectively, are determined for 70-90 NS polar winter latitudes over altitudes of 40-56 km. Additional OH bands, such as (3-2), (3-1), and (4-2), present ?1? measurements. Uncertainty in the (4-2) band emission rate contributes to increased uncertainty in the determination of the O2(1?g) (0-0)/(0-1) band emission ratio A00/A01=47-12+26. An average profile retrieval for Mars OH polar nightglow indicates 45-55 km altitude levels for volume emission rates (VER) of 0.4 (2-0) to 2 (1-0, 2-1) × 104 photons/(cm3 s). Similar to polar night O2(1?g) emission (e.g. Clancy, R.T. et al. [2012]. J. Geophys. Res. (Planets) 117, E00J10. http://dx.doi.org/10.1029/2011JE004018), Meinel OH band emission is supported by upper level, winter poleward transport of O and H in the deep Hadley solsticial circulations of Mars. The retrieved OH emission rates are compared to polar winter OH nightglow simulated by the LMD (Laboratoire de Météorologie Dynamique) photochemical GCM (global climate model), employing detailed photochemistry (e.g. Lefèvre, F., Lebonnois, S., Montmessin, F., Forget, F. [2004]. J. Geophys. Res. (Planets) 109, E07004. http://dx.doi.org/10.1029/2004JE002268) and energy transfer processes (excitation and quenching) developed for Mars Meinel OH band nightglow by García Muñoz et al. (García Muñoz, A., McConnell, J.C., McDade, I.C., Melo, S.M.L. [2005]. Icarus 176, 75-95). Modeled versus observed OH emission behavior agrees within measurement uncertainties with the assumptions of a Bates-Nicolet (H + O3) source for excited OH production, and 'collisional-cascade' quenching of the OH vibrational population by CO2. 'Sudden-death' quenching of excited OH by CO2 leads to 100× less OH emission than observed. The combined agreement between LMD GCM simulated and CRISM observed O2(1?g) and Meinel OH polar nightglow behaviors represents a significant demonstration of the LMD model capability to couple odd oxygen and hydrogen photochemistry and transport by the Mars global circulation in a realistic fashion.

  3. Comparison between ECMWF L-band brightness temperatures and SMOS observations using the Community Microwave Emission Modelling Platform (CMEM)

    NASA Astrophysics Data System (ADS)

    de Rosnay, Patricia; Muñoz Sabater, Joaquín; Dutra, Emanuel; Albergel, Clément; Balsamo, Gianpaolo; Boussetta, Souhail; Isaksen, Lars

    2015-04-01

    Soil moisture initialisation is crucial for Numerical Weather Prediction (NWP). New generations of satellites, such as SMOS (Soil Moisture and Ocean Salinity) and SMAP (Soil Moisture Active and Passive) provide highly suitable data from passive and active microwave sensors for soil moisture remote sensing. In order to make it possible to combine use of satellite, in situ and proxy observations to analyse soil moisture, ECMWF implemented an Extended Kalman Filter (EKF) soil moisture analysis which is used for operational NWP in the ECMWF Integrated Forecasting System (IFS). The use of passive microwave sensors in the EKF soil moisture data assimilation requires an accurate radiative transfer model. In this poster we present ECMWF developments in radiative transfer modelling conducted to use SMOS and SMAP brightness temperature observations in the ECMWF data assimilation system. The ECMWF Community Microwave Emission Modelling Platform (CMEM) is described. CMEM input global fields, including soil moisture, soil temperature, snow depth and vegetation cover, were obtained from H-TESSEL land surface model simulations forced by ERA-Interim atmospheric conditions. CMEM multi-year simulations were performed using a land surface model configuration which is similar to the current operational IFS. In CMEM, combinations of three soil dielectric models, three vegetation opacity models and four soil roughness parametrizations were used, allowing comparing 36 different configurations of the microwave emission model. Global scale forward simulations of dual polarization L-band (1.4 GHz) brightness temperature were conducted at 40 degrees incidence angle for each radiative transfer model and evaluated using the SMOS near real time brightness temperature data for 2010. Best microwave emission model performances were obtained with the Wang and Schmugge dielectric model combined with the Wigneron vegetation opacity model and the simple Wigneron soil roughness parametrization. The best CMEM configuration was used to simulate multi-angular brightness temperature at 30, 40 and 50 degrees incidence angle for 2010-2013 and evaluated against the observed SMOS brightness temperature. Results are presented at global and regional scales using RMSE, correlation and bias metrics in order to evaluate CMEM both at the monthly and annual time scales.

  4. Ballistic-electron-emission spectroscopy of Al{sub x}Ga{sub 1{minus}x}As/GaAs heterostructures: Conduction-band offsets, transport mechanisms, and band-structure effects

    SciTech Connect

    OShea, J.J.; Brazel, E.G.; Rubin, M.E.; Bhargava, S.; Chin, M.A.; Narayanamurti, V.

    1997-07-01

    We report an extensive investigation of semiconductor band-structure effects in single-barrier Al{sub x}Ga{sub 1{minus}x}As/GaAs heterostructures using ballistic-electron-emission spectroscopy (BEES). The transport mechanisms in these single-barrier structures were studied systematically as a function of temperature and Al composition over the full compositional range (0{le}x{le}1). The initial ({Gamma}) BEES thresholds for Al{sub x}Ga{sub 1{minus}x}As single barriers with 0{le}x{le}0.42 were extracted using a model which includes the complete transmission probability of the metal-semiconductor interface and the semiconductor heterostructure. Band offsets measured by BEES are in good agreement with previous measurements by other techniques which demonstrates the accuracy of this technique. BEES measurements at 77 K give the same band-offset values as at room temperature. When a reverse bias is applied to the heterostructures, the BEES thresholds shift to lower voltages in good agreement with the expected bias-induced band-bending. In the indirect band-gap regime ({ital x}{gt}0.45), spectra show a weak ballistic-electron-emission microscopy current contribution due to intervalley scattering through Al{sub x}Ga{sub 1{minus}x}As {ital X} valley states. Low-temperature spectra show a marked reduction in this intervalley current component, indicating that intervalley phonon scattering at the GaAs/Al{sub x}Ga{sub 1{minus}x}As interface produces a significant fraction of this{ital X} valley current. A comparison of the BEES thresholds with the expected composition dependence of the Al{sub x}Ga{sub 1{minus}x}As {Gamma}, {ital L}, and {ital X} points yields good agreement over the entire composition range. {copyright} {ital 1997} {ital The American Physical Society}

  5. Spatial Resolution of High-Velocity Filaments in the Narrow-Line Region of NGC 1068: Associated Absorbers Caught in Emission?

    E-print Network

    Gerald Cecil; Michael A. Dopita; Brent Groves; Andrew S. Wilson; Pierre Ferruit; Emmanuel Pécontal; Luc Binette

    2001-12-12

    Using the HST STIS spectrograph we have obtained a grid of [O III] and H-beta emission-line spectra at 0"05x0"19 and 60 km/s (FWHM) resolution that covers much of the NLR of NGC 1068. We find emitting knots that have blueshifted radial velocities up to 3200 km/s relative to galaxy systemic, are 70-150 pc NE of the nucleus and up to 40 pc from the radio jet, emit several percent of the NLR line flux but no significant continuum, span velocity extents of up to 1250 km/s but a small fraction of the sky seen from the nucleus, coincide with a region of enhanced IR coronal-line emission, and have ionized masses $\\sim$200 Msun/ne4 (ne4=10^4 cm^{-3}). We argue that the blueshifted knots are ablata from disintegrating molecular clouds that are being photoionized by the AGN, and are being accelerated readiatively by the AGN or mechanically by the radio jet. In their kinematic properties, the knots resemble the associated absorbers seen projected on the UV continua of some AGN. Between 2"5-4"5 from the nucleus, emission is redshifted relative to systemic, a pattern that we interpret as gas in the galaxy disk being pushed away from us by the NE radio lobe.

  6. Two dimensional expansion effects on angular distribution of 13.5 nm in-band extreme ultraviolet emission from laser-produced Sn plasma

    SciTech Connect

    Sequoia, K. L.; Tao, Y.; Yuspeh, S.; Burdt, R.; Tillack, M. S.

    2008-06-02

    The angular distribution of extreme ultraviolet emission at 13.5 nm within 2% bandwidth was characterized for laser irradiated, planar, Sn targets at prototypic conditions for a lithography system. We have found that two dimensional plasma expansion plays a key role in the distribution of in-band 13.5 nm emission under these conditions. The angular distribution was found to have two peaks at 45 deg. and 15 deg. This complex angular distribution arises from the shape of both the emitting plasma and the surrounding absorbing plasma. This research reveals that the detailed angular distribution can be important to the deduction of conversion efficiency.

  7. Unpolarized emissivity with shadow and multiple reflections from random rough surfaces with the geometric optics approximation: application to Gaussian sea surfaces in the infrared band.

    PubMed

    Bourlier, Christophe

    2006-08-20

    The emissivity from a stationary random rough surface is derived by taking into account the multiple reflections and the shadowing effect. The model is applied to the ocean surface. The geometric optics approximation is assumed to be valid, which means that the rough surface is modeled as a collection of facets reflecting locally the light in the specular direction. In particular, the emissivity with zero, single, and double reflections are analytically calculated, and each contribution is studied numerically by considering a 1D sea surface observed in the near infrared band. The model is also compared with results computed from a Monte Carlo ray-tracing method. PMID:16892130

  8. Interaction of wide band gap single crystals with 248 nm excimer laser radiation. XII. The emission of negative atomic ions from alkali halides

    SciTech Connect

    Kimura, Kenichi; Langford, S. C.; Dickinson, J. T.

    2007-12-01

    Many wide band gap materials yield charged and neutral emissions when exposed to sub-band-gap laser radiation at power densities below the threshold for optical breakdown and plume formation. In this work, we report the observation of negative alkali ions from several alkali halides under comparable conditions. We observe no evidence for negative halogen ions, in spite of the high electron affinities of the halogens. Significantly, the positive and negative alkali ions show a high degree of spatial and temporal overlap. A detailed study of all the relevant particle emissions from potassium chloride (KCl) suggests that K{sup -} is formed by the sequential attachment of two electrons to K{sup +}.

  9. Origin of 3.45 eV Emission Line and Yellow Luminescence Band in GaN Nanowires: Surface Microwire and Defect.

    PubMed

    Huang, Pu; Zong, Hua; Shi, Jun-jie; Zhang, Min; Jiang, Xin-he; Zhong, Hong-xia; Ding, Yi-min; He, Ying-ping; Lu, Jing; Hu, Xiao-dong

    2015-09-22

    The physical origin of the strong emission line at 3.45 eV and broadening yellow luminescence (YL) band centered at 2.2 eV in GaN nanowire (NW) has been debated for many years. Here, we solve these two notable issues by using state-of-the-art first-principles calculations based on many-body perturbation theory combined with polarization-resolved experiments. We demonstrate that the ubiquitous surface "microwires" with amazing characteristics, i.e., the outgrowth nanocrystal along the NW side wall, are vital and offer a new perspective to provide insight into some puzzles in epitaxy materials. Furthermore, inversion of the top valence bands, in the decreasing order of crystal-field split-off hole (CH) and heavy/light hole, results in the optical transition polarized along the NW axis due to quantum confinement. The optical emission from bound excitons localized around the surface microwire to CH band is responsible for the 3.45 eV line with E?c polarization. Both gallium vacancy and carbon-related defects tend to assemble at the NW surface layer, determining the broadening YL band. PMID:26301765

  10. Spectroscopy of Fe L-shell line emission from Fe XVII- XXIV in the 10--18 A wavelength band

    NASA Astrophysics Data System (ADS)

    Brown, Gregory Vallee

    2000-09-01

    The line emission from the L-shell, n --> 2, transitions in Fe XVII-XXIV falling in the ultra-soft x-ray regime from 10-18 Å has been measured using the Electron Beam Ion Trap located at the Lawrence Livermore National Laboratory. The results of these measurements include wavelengths, relative intensities, and line identifications of over 150 features from Fe XVIII-XXIV. In addition, measurements of the intensity of the high- n L-shell transitions, i.e., n >= 5, in Fe XVII falling in the 9.8-11.5 Å wavelength band have been made. These measurements were done at single electron beam energies where the only population process is direct excitation followed by radiative cascades. Also presented in this work are the results of a systematic study of the relative and absolute cross sections of the 1s22s 22p1/22 p43/2 3d3/2J = 1 --> 1 s22s22p 6 J = 0 resonance to ls2 2s22 p21/2 2 p33/2 3d5/2J = 1 --> 1 s22s22p 6 J = 0 intercombination line in neon-like Fe XVII. This ratio was measured under conditions where different processes contribute to the line flux. The contributing processes are direct impact excitation followed by radiative cascades, blending with Fe XVI innershell satellites, and Fe XVI dielectronic recombination satellites involving capture into high- n levels. The measured ratio varies between 2.8 and 3.2 depending on the line formation processes. These values are higher than ratios measured in non-flaring active regions of the Sun. However, the measurements are significantly lower than values calculated with current atomic physics codes demonstrating that calculational methods are not yet accurate enough to provide relative intensities useful for comparative diagnostics. The results suggest that the relatively low ratio measured in non-flaring active regions may be a result of blending with innershell satellites of Fe XVI.

  11. Optical spectroscopy of IRAS sources with infrared emission bands. II. IRAS 04324+5106, 06114+1745, 20319+3958, and 22539+5758

    SciTech Connect

    Cohen, M.; Jones, B.F.; Walker, H.J.; Lick Observatory, Santa Cruz, CA; Search for Extraterrestrial Intelligence Institute, Los Altos, CA )

    1989-06-01

    The paper presents long-slit optical spectra and microwave CO spectra of four nebulous counterparts to IRAS sources showing PAH emission features: 04324+5106, 06114+1745, 20319+3958, and 22539+5758. IRAS 22539+5758 is associated with a bipolar nebula. All are allied with B-type stars that suffer appreciable circumstellar extinction, and whose environs show atomic emission lines; three represent mixed reflection/emission nebulosities. Three show spectroscopic evidence for outflows at about 100 km/s. One, 06114+1745, exhibits indications of enhanced diffuse interstellar bands. It is concluded that extinction alone is insufficient to yield enhanced DIBs and that peculiar circumstellar abundances and/or physical conditions must play a role. 20 refs.

  12. Analysis and Modeling of Jovian Radio Emissions Observed by Galileo

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.

    2003-01-01

    Our studies of Jovian radio emission have resulted in the publication of five papers in refereed journals, with three additional papers in progress. The topics of these papers include the study of narrow-band kilometric radio emission; the apparent control of radio emission by Callisto; quasi-periodic radio emission; hectometric attenuation lanes and their relationship to Io volcanic activity; and modeling of HOM attenuation lanes using ray tracing. A further study of the control of radio emission by Jovian satellites is currently in progress. Abstracts of each of these papers are contained in the Appendix. A list of the publication titles are also included.

  13. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 108 2

    NASA Technical Reports Server (NTRS)

    Valdez, A.

    2000-01-01

    This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1 SIN 108, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  14. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 109

    NASA Technical Reports Server (NTRS)

    Valdez, A.

    2000-01-01

    This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A1, S/N 109, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  15. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A2, S/N 108, 08

    NASA Technical Reports Server (NTRS)

    Valdez, A.

    2000-01-01

    This is the Engineering Test Report, Radiated Emissions and SARR, SARP, DCS Receivers, Link Frequencies EMI Sensitive Band Test Results, AMSU-A2, S/N 108, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  16. Search for the OH (X(2)Pi) Meinel band emission in meteors as a tracer of mineral water in comets: detection of N(2)(+) (A-X)

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Laux, Christophe O.

    2004-01-01

    We report the discovery of the N(2)(+) A-X Meinel band in the 780-840 nm meteor emission from two Leonid meteoroids that were ejected less than 1000 years ago by comet 55P/Tempel-Tuttle. Our analysis indicates that the N(2)(+) molecule is at least an order of magnitude less abundant than expected, possibly as a result of charge transfer reactions with meteoric metal atoms. This new band was found while searching for rovibrational transitions in the X(2)Pi electronic ground state of OH (the OH Meinel band), a potential tracer of water bound to minerals in cometary matter. The electronic A-X transition of OH has been identified in other Leonid meteors. We did not detect this OH Meinel band, which implies that the excited A state is not populated by thermal excitation but by a mechanism that directly produces OH in low vibrational levels of the excited A(2)Sigma state. Ultraviolet dissociation of atmospheric or meteoric water vapor is such a mechanism, as is the possible combustion of meteoric organics.

  17. Complex organic matter in space: about the chemical composition of carriers of the Unidentified Infrared Bands (UIBs) and protoplanetary emission spectra recorded from certain astrophysical objects.

    PubMed

    Cataldo, Franco; Keheyan, Yeghis; Heymann, Dieter

    2004-02-01

    In this communication we present the basic concept that the pure PAHs (Polycyclic Aromatic Hydrocarbons) can be considered only the ideal carriers of the UIBs (Unidentified Infrared Bands), the emission spectra coming from a large variety of astronomical objects. Instead we have proposed that the carriers of UIBs and of protoplanetary nebulae (PPNe) emission spectra are much more complex molecular mixtures possessing also complex chemical structures comparable to certain petroleum fractions obtained from the petroleum refining processes. The demonstration of our proposal is based on the comparison between the emission spectra recorded from the protoplanetary nebulae (PPNe) IRAS 22272+ 5435 and the infrared absorption spectra of certain 'heavy' petroleum fractions. It is shown that the best match with the reference spectrum is achieved by highly aromatic petroleum fractions. It is shown that the selected petroleum fractions used in the present study are able to match the band pattern of anthracite coal. Coal has been proposed previously as a model for the PPNe and UIBs but presents some drawbacks which could be overcome by adopting the petroleum fractions as model for PPNe and UIBs in place of coal. A brief discussion on the formation of the petroleum-like fractions in PPNe objects is included. PMID:14979641

  18. Temperature profile retrieval in axisymmetric combustion plumes using multilayer perceptron modeling and spectral feature selection in the infrared CO2 emission band.

    PubMed

    García-Cuesta, Esteban; de Castro, Antonio J; Galván, Inés M; López, Fernando

    2014-01-01

    In this work, a methodology based on the combined use of a multilayer perceptron model fed using selected spectral information is presented to invert the radiative transfer equation (RTE) and to recover the spatial temperature profile inside an axisymmetric flame. The spectral information is provided by the measurement of the infrared CO2 emission band in the 3-5 ?m spectral region. A guided spectral feature selection was carried out using a joint criterion of principal component analysis and a priori physical knowledge of the radiative problem. After applying this guided feature selection, a subset of 17 wavenumbers was selected. The proposed methodology was applied over synthetic scenarios. Also, an experimental validation was carried out by measuring the spectral emission of the exhaust hot gas plume in a microjet engine with a Fourier transform-based spectroradiometer. Temperatures retrieved using the proposed methodology were compared with classical thermocouple measurements, showing a good agreement between them. Results obtained using the proposed methodology are very promising and can encourage the use of sensor systems based on the spectral measurement of the CO2 emission band in the 3-5 ?m spectral window to monitor combustion processes in a nonintrusive way. PMID:25061791

  19. Comparison of S-band radio-frequency field emission performance of nitrogen-doped nanocrystalline diamond before and after O2/Ar plasma etching

    NASA Astrophysics Data System (ADS)

    Han, Wenhong; Xiong, Ying; Wang, Bing; Li, Xiangkun; Xu, Li

    2015-08-01

    The effect of surface nanostructuring via reactive O2/Ar plasma etching on the S-band radio-frequency (RF) field emission performance for nitrogen-doped nanocrystalline diamond (N-NCD) films was preliminarily investigated. A transition in terms of surface morphology, from dense flower-like aggregated shape having low roughness (?41 nm) to uniform porous structure with increased surface roughness (?104 nm), was observed after plasma etching. Raman spectra revealed there was no obvious change in the bonding characteristics between the pristine and nanostructured N-NCD films. At surface RF gradient of 72.1 MV/m, maximum current density of 80.2 mA/cm2 was reached for the nanostructured N-NCD cathode, increasing about 41% compared to that of the pristine N-NCD cathode. Furthermore, the mechanism in the enhanced RF field emission was tentatively discussed through the measured Fowler-Nordheim (F-N) features.

  20. Simultaneous K- and L-band Spectroscopy of Be Stars: Circumstellar Envelope Properties from Hydrogen Emission Lines

    NASA Astrophysics Data System (ADS)

    Granada, A.; Arias, M. L.; Cidale, L. S.

    2010-05-01

    We present medium-resolution K- and L-band spectra of a sample of eight Be stars, obtained with Gemini/NIRI. The IR K and L bands contain many lines of different hydrogen series that are used as a diagnosis to the physical conditions in the circumstellar environments. We make an analysis on the optical depths of the line-forming regions based on the intensity ratios of Pf? and Br? lines, the behavior of Humphreys' series, and the fluxes of Br? and Br? lines. All our targets show spectroscopic and photometric long-term variability; thus, time-resolved K- and L-band spectroscopy is an ideal tool for studying the structure and evolution of the innermost regions of the envelope and to test models on the disk-forming mechanism. We note that the instrumental configuration used allowed us to obtain good quality IR observations and to take profit of Gemini band 3 observing time (allocation time for ranked programs in which the observing conditions are relaxed). Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (USA), the Science and Technology Facilities Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil), and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

  1. On sky characterization of the BAORadio wide band digital backend - Search for H I emission in Abell85, Abell1205 and Abell2440 galaxy clusters

    NASA Astrophysics Data System (ADS)

    Ansari, R.; Campagne, J. E.; Colom, P.; Ferrari, C.; Magneville, Ch.; Martin, J. M.; Moniez, M.; Torrentó, A. S.

    2015-09-01

    We have observed regions of three galaxy clusters at z˜[0.06÷0.09] (Abell85, Abell1205, Abell2440) with the Nançay radiotelescope (NRT) to search for 21 cm emission and to fully characterize the FPGA based BAORadio digital backend. We have tested the new BAORadio data acquisition system by observing sources in parallel with the NRT standard correlator (ACRT) back-end over several months. BAORadio enables wide band instantaneous observation of the [1250,1500] MHz frequency range, as well as the use of powerful RFI mitigation methods thanks to its fine time sampling. A number of questions related to instrument stability, data processing and calibration are discussed. We have obtained the radiometer curves over the integration time range [0.01,10 000] seconds and we show that sensitivities of few mJy over most of the wide frequency band can be reached with the NRT. It is clearly shown that in blind line search, which is the context of H I intensity mapping for Baryon Acoustic Oscillations, the new acquisition system and processing pipeline outperforms the standard one. We report a positive detection of 21 cm emission at 3?-level from galaxies in the outer region of Abell85 at ?1352 MHz (14400 km/s) corresponding to a line strength of ?0.8 Jy km/s. We also observe an excess power around ?1318 MHz (21600 km/s), although at lower statistical significance, compatible with emission from Abell1205 galaxies. Detected radio line emissions have been cross matched with optical catalogs and we have derived hydrogen mass estimates.

  2. Operation of an ungated diamond field-emission array cathode in a L-band radiofrequency electron source

    SciTech Connect

    Piot, P.; Brau, C. A.; Gabella, W. E.; Ivanov, B.; Mendenhall, M. H.; Choi, B. K.; Blomberg, B.; Mihalcea, D.; Panuganti, H.; Jarvis, J.; Prieto, P.; Reid, J.

    2014-06-30

    We report on the operation of a field-emitter-array cathode in a conventional L-band radio-frequency electron source. The cathode consisted of an array of ?10{sup 6} diamond tips on pyramids. Maximum current on the order of 15?mA was reached and the cathode did not show appreciable signs of fatigue after weeks of operation. The measured Fowler-Nordheim characteristics, transverse beam density, and current stability are discussed.

  3. The Peculiar Radio-Loud Narrow Line Seyfert 1 Galaxy 1H 0323+342

    E-print Network

    Paliya, Vaidehi S; Parker, M L; Fabian, A C; Stalin, C S; Anjum, Ayesha; Pandey, S B

    2014-01-01

    We present a multi-wavelength study of the radio-loud narrow line Seyfert 1 galaxy (NLSy1), 1H 0323+342, detected by Fermi Gamma Ray Space Telescope. Multi-band light curves show many orphan X-ray and optical flares having no corresponding {\\gamma}-ray counterparts. Such anomalous variability behavior can be due to different locations of the emission region from the central source. During a large flare, {\\gamma}-ray flux doubling time scale as small as $\\sim$ 3 hours is noticed. We built spectral energy distribution (SED) during different activity states and modeled them using an one-zone leptonic model. The shape of the optical/UV component of the SEDs is dominated by accretion disk emission in all the activity states. In the X-ray band, significant thermal emission from the hot corona is inferred during quiescent and first flaring states, however, during subsequent flares, non-thermal jet component dominates. The {\\gamma}-ray emission in all the states can be well explained by inverse-Compton scattering of ...

  4. Analysis of chorus emissions at Jupiter

    NASA Astrophysics Data System (ADS)

    Coroniti, F. V.; Scarf, F. L.; Kennel, C. F.; Kurth, W. S.

    1984-06-01

    The emissions in the chorus frequency band which were detected on the Voyager 1 inbound pass between about ten and six Jupiter radii are surveyed. An overview of the plasma and wave observations during the inbound pass is presented and the spatial regions in which chorus band signals were observed are discussed. A series of wide-band frequency-time frames which characterize the onset of two observed intervals of chorus band activity is displayed. A detailed examination is made of the spectra for rising chorus which sweeps upward in frequency from 0.2 to 0.5 times the electron cyclotron frequency f(c). Two temporally successive wide-band frames in which several types of chorus band emissions were observed are discussed. The spatial morphology of chorus is discussed in terms of the electron energies which resonate with whistler mode waves. A recent theory of chorus generation is reviewed along with theories and a model explaining the narrow-band emissions above f(c)/2.

  5. The Origin of Double-peaked Narrow Lines in Active Galactic Nuclei. I. Very Large Array Detections of Dual AGNs and AGN Outflows

    NASA Astrophysics Data System (ADS)

    Müller-Sánchez, F.; Comerford, J. M.; Nevin, R.; Barrows, R. S.; Cooper, M. C.; Greene, J. E.

    2015-11-01

    We have examined a subset of 18 active galactic nuclei (AGNs) drawn from a sample of 81 galaxies that possess double-peaked narrow optical emission line spectra in the Sloan Digital Sky Survey, have 2 optical AGN emission components separated by >0.?2, and are detected in the Faint Images of the Radio Sky at Twenty-centimeters survey. Without follow-up observations, the sources of the double-peaked narrow emission lines are uncertain, and may be produced by kiloparsec-scale separation dual active supermassive black holes, AGN outflows, or disk rotation. In this work, we propose a new methodology to characterize double-peaked narrow emission line galaxies based on optical long-slit spectroscopy and high-resolution multi-band Very Large Array observations. The nature of the radio emission in the sample galaxies is varied. Of the 18 galaxies, we detect 2 compact flat-spectrum radio cores with projected spatial separations on the sky between 0.6 and 1.6 kpc in 3 galaxies: J1023+3243, J1158+3231, and J1623+0808. The two radio sources are spatially coincident with the two optical components of ionized gas with AGN-like line ratios, which confirms the presence of dual AGNs in these three galaxies. Dual AGNs account for only ?15% (3/18) of the double-peaked AGNs in our sample. Gas kinematics produce ?75% (13/18) of the double-peaked narrow emission lines, distributed in the following way: seven AGN wind-driven outflows, five radio-jet driven outflows, and one rotating narrow-line region. The remaining 10% (2/18) are ambiguous cases. Our method demonstrates the power of spatially resolved spectroscopy and high-resolution radio observations for the identification of AGN outflows and AGN pairs with angular separations as small as 0.?18. Based on observations at the NRAO Karl G. Jansky VLA (program 12A-103).

  6. Ring resonator based narrow-linewidth semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Ksendzov, Alexander (Inventor)

    2005-01-01

    The present invention is a method and apparatus for using ring resonators to produce narrow linewidth hybrid semiconductor lasers. According to one embodiment of the present invention, the narrow linewidths are produced by combining the semiconductor gain chip with a narrow pass band external feedback element. The semi conductor laser is produced using a ring resonator which, combined with a Bragg grating, acts as the external feedback element. According to another embodiment of the present invention, the proposed integrated optics ring resonator is based on plasma enhanced chemical vapor deposition (PECVD) SiO.sub.2 /SiON/SiO.sub.2 waveguide technology.

  7. Narrow line-width phosphors for phosphor-converted white light emitting diodes

    NASA Astrophysics Data System (ADS)

    Khanna, Aloka

    The luminous efficacy of present day phosphor-converted white LEDs is limited by phosphors with broad spectral emission in the long wavelength visible range (600-700 nm). The light output from the cool-white LEDs that do not use a red phosphor is 30-35% higher than the warm white LEDs fabricated with a red phosphor in addition to the yellow phosphor. However, the CRI of cool-white LEDs is significantly lower (~60-70) than the CRI of the warm white LEDs (~80-95) due to lack of the red photons in the emission spectrum. Therefore, a trade-off exists between luminous efficacy and color rendering capability of light generated by phosphor-converted white LEDs. In order to solve this problem, an efficient red phosphor with considerably narrow full width of half maxima (~5-10 nm) and emission in the 600-650 nm wavelength range is required. The narrow spectral line-width can be achieved by introducing trivalent lanthanide ions like Eu3+, Pr3+ and Sm3+ (?peak- 615 nm, 650 nm, 655 nm) in oxide host lattices although the high energy gaps of these hosts makes these phosphors unsuitable for excitation with near-UV/Blue (380-470 nm) LED sources. Therefore, the goal of this project is two-fold- to develop new material systems which can serve as potential hosts for trivalent lanthanide ions like Eu3+, Pr3+ and Sm3+ (?peak- 615 nm, 650 nm, 655 nm) with strong excitation bands in the near-UV/blue wavelength region (380-470 nm) and improve the efficiency of the known oxide phosphors doped with trivalent lanthanide ions and the novel phosphors via crystal growth processes. Moreover, phosphors in the green-yellow wavelength region with a narrow emission line-width have the potential of improving the luminous efficacy of the phosphor-converted LEDs as the human eye sensitivity curve peaks at 555 nm. Thus, in parallel with the narrow line-width red phosphor research, new compositions doped with Tb3+ (550 nm), Dy3+ (575 nm), etc. are being explored with strong excitation bands in near-UV/blue region (380-470 nm).

  8. Non-thermal emission from extragalactic radio sources: a high resolution broad band (radio to X-rays) approach

    E-print Network

    Gianfranco Brunetti

    2002-07-31

    In the framework of the study of extragalactic radio sources, we will focus on the importance of the spatial resolution at different wavelengths, and of the combination of observations at different frequency bands. In particular, a substantial step forward in this field is now provided by the new generation X-ray telescopes which are able to image radio sources in between 0.1--10 keV with a spatial resolution comparable with that of the radio telescopes (VLA) and of the optical telescopes. After a brief description of some basic aspects of acceleration mechanisms and of the radiative processes at work in the extragalactic radio sources, we will focus on a number of recent radio, optical and X-ray observations with arcsec resolution, and discuss the deriving constraints on the physics of these sources.

  9. Confinement effect of laser ablation plume in liquids probed by self-absorption of C{sub 2} Swan band emission

    SciTech Connect

    Sakka, Tetsuo; Saito, Kotaro; Ogata, Yukio H.

    2005-01-01

    The (0,0) Swan band of the C{sub 2} molecules in a laser ablation plume produced on the surface of graphite target submerged in water was used as a probe to estimate the density of C{sub 2} molecules in the plume. Observed emission spectra were reproduced excellently by introducing a self-absorption parameter to the theoretical spectral profile expected by a rotational population distribution at a certain temperature. The optical density of the ablation plume as a function of time was determined as a best-fit parameter by the quantitative fitting of the whole spectral profile. The results show high optical densities for the laser ablation plume in water compared with that in air. It is related to the plume confinement or the expansion, which are the important phenomena influencing the characteristics of laser ablation plumes in liquids.

  10. Visible and Near-Infrared Spectroscopy of Seyfert 1 and Narrow-Line Seyfert 1 Galaxies

    NASA Astrophysics Data System (ADS)

    Rodríguez-Ardila, Alberto; Pastoriza, Miriani G.; Donzelli, Carlos J.

    2000-01-01

    This paper studies the continuum and emission-line properties of a sample composed of 16 normal Seyfert 1 and seven narrow-line Seyfert 1 (NLS1) galaxies using optical and near-IR CCD spectroscopy. The continuum emission of the galaxies can be described in terms of a combination of stellar population, a nonstellar continuum of power-law form, and Fe II emission. A significative difference in the optical spectral index between NLS1's and normal Seyfert 1's is observed; the latter is steeper. Most NLS1's show Fe II/H? ratios larger than those observed in the other Seyfert 1's. In the IRAS band, both groups of galaxies have very similar properties. We have searched for the presence of optically thin gas in the broad-line region (BLR) of the galaxies by comparing the broad O I ?8446 and H? emission-line profiles. Our analysis show that in the NLS1's, both profiles are similar in shape and width. This result contradicts the hypothesis of thin gas emission in the high-velocity part of the BLR to explain the ``narrowness'' of broad optical permitted lines in these objects. Evidence of narrow O I ?8446 emission is found in six galaxies of our sample, implying that this line is not restricted to a pure BLR phenomenon. In the narrow-line region, we find similar luminosities in the permitted and high-ionization lines of NLS1's and normal Seyfert 1's. However, low-ionization lines such as [O I] ?6300, [O II] ?3727, and [S II] ??6717, 6731 are intrinsically less luminous in NLS1's. Physical properties derived from density- and temperature-sensitive line ratios suggest that the [O II] and [S II] emitting zones are overlapping in normal Seyfert 1's and separated in NLS1's. Based on observations made at CASLEO. Complejo Astronómico El Leoncito (CASLEO) is operated under agreement between the Consejo Nacional de Investigaciones Científicas y técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juán.

  11. The broad-band X-ray spectrum of a QSO sample

    NASA Technical Reports Server (NTRS)

    Worrall, D. M.; Marshall, F. E.

    1983-01-01

    A sample of 25 QSOs was used to investigate the average spectrum between the soft X-ray energy band of the Einstein Observatory image proportional counter, and the higher energy band of the HEAO 1 A2 experiment. The spectrum is similar to thoe exhibited by Seyfert galaxies and narrow emission line galaxies above 2 keV. The spectrum is soft enough that if these objects are typical of the higher redshift, more radio-quiet QSOs, then it is possible to exclude QSOs as being the dominant origin of the diffuse X-ray background.

  12. Narrow Angle movie

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This brief three-frame movie of the Moon was made from three Cassini narrow-angle images as the spacecraft passed by the Moon on the way to its closest approach with Earth on August 17, 1999. The purpose of this particular set of images was to calibrate the spectral response of the narrow-angle camera and to test its 'on-chip summing mode' data compression technique in flight. From left to right, they show the Moon in the green, blue and ultraviolet regions of the spectrum in 40, 60 and 80 millisecond exposures, respectively. All three images have been scaled so that the brightness of Crisium basin, the dark circular region in the upper right, is the same in each image. The spatial scale in the blue and ultraviolet images is 1.4 miles per pixel (2.3 kilometers). The original scale in the green image (which was captured in the usual manner and then reduced in size by 2x2 pixel summing within the camera system) was 2.8 miles per pixel (4.6 kilometers). It has been enlarged for display to the same scale as the other two. The imaging data were processed and released by the Cassini Imaging Central Laboratory for Operations (CICLOPS) at the University of Arizona's Lunar and Planetary Laboratory, Tucson, AZ.

    Photo Credit: NASA/JPL/Cassini Imaging Team/University of Arizona

    Cassini, launched in 1997, is a joint mission of NASA, the European Space Agency and Italian Space Agency. The mission is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Space Science, Washington DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

  13. Broad-Band Continuum and Line Emission of the gamma-Ray Blazar PKS 0537-441

    NASA Technical Reports Server (NTRS)

    Pian, E.; Falomo, R.; Hartman, R. C.; Maraschi, L.; Tavecchio, F.; Tornikoski, M.; Treves, A.; Urry, C. M.; Ballo, L.; Mukherjee, R.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    PKS 0537-441, a bright gamma ray emitting blazar was observed at radio, optical, UV and X-ray frequencies during various EGRET paintings, often quasi-simultaneously. In 1995 the object was found in an intense emission state at all wavelengths. BeppoSAX observations made in 1998, non-simultaneously with exposures at other frequencies, allow us to characterize precisely the spectral shape of the high energy blazer component, which we attribute to inverse Compton scatter in The optical-to-gamma-ray spectral energy distributions at the different epochs show that the gamma-ray luminosity dominates the barometric output. This, together with the presence of optical and UV line emission, suggests that, besides the synchrotron self-Compton mechanism, the Compton upscattering of photons external to the jet (e.g., in the broad line region) may have a significant role for high energy radiation. The multiwavelength variability can be reproduced by changes of the plasma bulk Lorentz factor. The spectrum secured by ICE in 1995 appears to be partially absorbed shortward of approximately 1700 Angstroms. However, this signature is not detected in the HST spectrum taker during a lower state of the source. The presence of intervening absorbers is not supported by optical imaging and spectroscopy of the field.

  14. The Origin of Double-Peaked Narrow Lines in Active Galactic Nuclei I: Very Large Array Detections of Dual AGNs and AGN Outflows

    E-print Network

    Müller-Sanchez, Francisco; Nevin, Rebecca; Barrows, R Scott; Cooper, Michael C; Greene, Jenny E

    2015-01-01

    We have examined a subset of 18 active galactic nuclei (AGNs) drawn from a sample of 81 galaxies that possess double-peaked narrow optical emission line spectra in the Sloan Digital Sky Survey, have two optical AGN emission components separated by >0.2", and are detected in the Faint Images of the Radio Sky at Twenty-centimeters survey. Without follow-up observations, the sources of the double-peaked narrow emission lines are uncertain, and may be produced by kpc-scale separation dual active supermassive black holes, AGN outflows, or disk rotation. In this work, we propose a new methodology to characterize double-peaked narrow emission-line galaxies based on optical long-slit spectroscopy and high resolution multi-band Very Large Array observations. The nature of the radio emission in the sample galaxies is varied. Of the 18 galaxies, we detect two compact flat-spectrum radio cores with projected spatial separations on the sky between 0.6-1.6 kpc in three galaxies: J1023+3243, J1158+3231, and J1623+0808. The ...

  15. Contamination of Broad-Band Photometry by Nebular Emission in High Redshift Galaxies: Investigations with Keck's MOSFIRE Near-Infrared Spectrograph

    E-print Network

    Schenker, Matthew A; Konidaris, Nick P; Stark, Daniel P

    2013-01-01

    Earlier work has raised the potential importance of nebular emission in the derivation of the physical characteristics of high redshift Lyman break galaxies. Within certain redshift ranges, and especially at z ~ 6-7, such lines may be strong enough to reduce estimates of the stellar masses and ages of galaxies compared those derived assuming broad-band photometry represents stellar light alone. To test this hypothesis at the highest redshifts where such lines can be probed with ground-based facilities, we examine the near-infrared spectra of a representative sample of 20 3.0 < z < 3.8 Lyman break galaxies using the newly-commissioned MOSFIRE near-infrared spectrograph at the Keck I telescope. We use this data to derive the rest-frame equivalent widths (EW) of [O III] emission and show that these are comparable to estimates derived using the SED fitting technique introduced for sources of known redshift by Stark et al (2013). Although our current sample is modest, its [O III] EW distribution is consisten...

  16. Sub-photospheric, Radiation-mediated Shocks In Gamma-Ray Bursts: Multiple Shock Emission and the Band Spectrum

    NASA Astrophysics Data System (ADS)

    Keren, Shai; Levinson, Amir

    2014-07-01

    We compute the time-integrated, thermal emission produced by a series of radiation-mediated shocks that emerge from the photosphere of a gamma-ray burst outflow. We show that for a sufficiently broad distribution of shock strengths, the overall shape of the time-integrated spectral energy distribution below the peak is a power law, ?E ?vprop??, with a slope of 1 < ? < 2. A substructure in the spectral energy distribution (SED) can also be produced in this model for certain choices of the shock train distribution. In particular, we demonstrate that our model can reproduce the double-peak SED observed in some bursts, in events where a strong shock is followed by a sequence of sufficiently weaker ones.

  17. Combination Of Narrow Bandwidth Excimer Laser And Monochromatic Reduction Projection Lens

    NASA Astrophysics Data System (ADS)

    Kajiyama, K.; Saito, K.; Moro, N.; Maeda, Y.; Natsuaki, H.

    1988-01-01

    This paper will discuss the problems associated with excimer laser photo-lithography -the combination of a KrF narrow band width excimer laser (non-injection locked type) with a large field fused silica monochromatic reduction lens. An excimer laser with a KrF narrow bandwidth, in combination with a large field monochromatic lens which is appropriate for use with such laser, have been developed and tested. The system's resolution capability has been confirmed at 0.4 um L/S with MP2400 resist. The laser has been designed so as to be installed and maintained in a clean room environment as well as to have a very narrow spectrum line. A very narrow band-width beam, down to 0.003nm, has been attained through a stable resonator with more than 20mJ pulse energy. The ultra-compact laser head (300mm x 545mm x 1100mm) contains a small laser discharge unit (182mm x 156mm x 584mm), and no amplifier because the oscillator is highly efficient in spite of the narrow line emission. Maintenance is much easier in the clean room environment. Users can replace the discharge unit as easily as they would change Hg-lamp, only taking twenty minutes, and while they clean the window and check the electrodes of the removed unit, the laser can be operated with the easily installed replacement -already passivated discharge unit. The laser head unit is separated from a gas circulating unit and trigger pulse circuit - vibration, heat, EMI noise and particle generation. Therefore, it can be installed even in the thermal clean chamber of a stepper. The N.A. (numerical aperture) of the monochromatic lens is 0.36 and the field size is 15mm x 15mm. In fact, three kinds of lenses with N.A.s of 0.4, 0.35 and 0.3 respectively, were designed and individually evaluated for their OTF's and defocus's dependence on the light source's spectral width, and also their co-relationship. In parallel, simulations on the relationship between each lens' chromatic aberration and laser spectral width were completed and such results have been integrated with the laser performance data ie. output power v.s. spectral line width, and its interactions from speckle noises/background emmissions per line. The system is capable of achieving a resolution preformance of 0.4 microns over a field measuring 15mm x 15mm, and it is very reliable for practical applications since it employs the combination of 5-7/1000nm spectral bandwidth excimer laser with N.A. 0.36 lens, which has been optimized from the preceding simulations and experimental data. When the N.A. of a lens is being determined it is necessary to take into consideration the spectral width of the light source because in the case of a narrow bandwidth laser, it would be difficult to satisfy two contradictory factor6 - speckle noises/background emissions and narrow bandwidths. An extremely narrow bandwidth laser (less than 3/1000nm) would be much less reliable as it would demand sophisticated configuration and adjustments. A monochromatic lens with a high N.A. would struggle in its efforts to locate such a very narrow linewidth industrial laser source with easy maintenance and compact size in the clean room environment.

  18. Emission polarization study on quartz and calcite.

    NASA Technical Reports Server (NTRS)

    Vincent, R. K.

    1972-01-01

    Calculation of the spectral emission polarization of quartz and calcite polished plates for observation angles of 20 and 70 deg by the substitution of complex index of refraction values for each mineral into Fresnel's equations. The emission polarization is shown to be quite wavelength-dependent, demonstrating that selected narrow or medium-width spectral bands exhibit a significantly higher percentage of polarization than a broad spectral band for these two minerals. Field measurements with a broadband infrared radiometer yield polarizations on the order of 2% for a coarse-grained granite rock and beach sand (both quartz-rich). This implies that a more sensitive detector with a selected medium-width filter may be capable of measuring emission polarization accurately enough to make this parameter useful as a remote sensing tool for discrimination among rocks on the basis of texture.

  19. NFC - Narrow Field Camera

    NASA Astrophysics Data System (ADS)

    Koukal, J.; Srba, J.; Gorková, S.

    2015-01-01

    We have been introducing a low-cost CCTV video system for faint meteor monitoring and here we describe the first results from 5 months of two-station operations. Our system called NFC (Narrow Field Camera) with a meteor limiting magnitude around +6.5mag allows research on trajectories of less massive meteoroids within individual parent meteor showers and the sporadic background. At present 4 stations (2 pairs with coordinated fields of view) of NFC system are operated in the frame of CEMeNt (Central European Meteor Network). The heart of each NFC station is a sensitive CCTV camera Watec 902 H2 and a fast cinematographic lens Meopta Meostigmat 1/50 - 52.5 mm (50 mm focal length and fixed aperture f/1.0). In this paper we present the first results based on 1595 individual meteors, 368 of which were recorded from two stations simultaneously. This data set allows the first empirical verification of theoretical assumptions for NFC system capabilities (stellar and meteor magnitude limit, meteor apparent brightness distribution and accuracy of single station measurements) and the first low mass meteoroid trajectory calculations. Our experimental data clearly showed the capabilities of the proposed system for low mass meteor registration and for calculations based on NFC data to lead to a significant refinement in the orbital elements for low mass meteoroids.

  20. Origin of wide-band IP type II bursts

    NASA Astrophysics Data System (ADS)

    Pohjolainen, S.; Allawi, H.; Valtonen, E.

    2013-10-01

    Context. Different types of interplanetary (IP) type II bursts have been observed, where the more usual ones show narrow-band and patchy emissions, sometimes with harmonics, and which at intervals may disappear completely from the dynamic spectrum. The more unusual bursts are wide-band and diffuse, show no patches or breaks or harmonic emission, and often have long durations. Type II bursts are thought to be plasma emission, caused by propagating shock waves, but a synchrotron-emitting source has also been proposed as the origin for the wide-band type IIs. Aims: Our aim is to find out where the wide-band IP type II bursts originate and what is their connection to particle acceleration. Methods: We analyzed in detail 25 solar events that produced well-separated, wide-band IP type II bursts in 2001-2011. Their associations to flares, coronal mass ejections (CMEs), and solar energetic particle events (SEPs) were investigated. Results: Of the 25 bursts, 18 were estimated to have heights corresponding to the CME leading fronts, suggesting that they were created by bow shocks ahead of the CMEs. However, seven events were found in which the burst heights were significantly lower and which showed a different type of height-time evolution. Almost all the analyzed wide-band type II bursts were associated with very high-speed CMEs, originating from different parts of the solar hemisphere. In terms of SEP associations, many of the SEP events were weak, had poor connectivity due to the eastern limb source location, or were masked by previous events. Some of the events had precursors in specific energy ranges. These properties and conditions affected the intensity-time profiles and made the injection-time-based associations with the type II bursts difficult to interpret. In several cases where the SEP injection times could be determined, the radio dynamic spectra showed other features (in addition to the wide-band type II bursts) that could be signatures of shock fronts. Conclusions: We conclude that in most cases (in 18 out of 25 events) the wide-band IP type II bursts can be plasma emission, formed at or just above the CME leading edge. The results for the remaining seven events might suggest the possibility of a synchrotron source. These events, however, occurred during periods of high solar activity, and coronal conditions affecting the results of the burst height calculations cannot be ruled out. The observed wide and diffuse emission bands may also indicate specific CME leading edge structures and special shock conditions. Figures 2-26 and Table 4 are available in electronic form at http://www.aanda.org

  1. Optimum filters for narrow-band frequency modulation.

    NASA Technical Reports Server (NTRS)

    Shelton, R. D.

    1972-01-01

    The results of a computer search for the optimum type of bandpass filter for low-index angle-modulated signals are reported. The bandpass filters are discussed in terms of their low-pass prototypes. Only filter functions with constant numerators are considered. The pole locations for the optimum filters of several cases are shown in a table. The results are fairly independent of modulation index and bandwidth.

  2. The Narrow-Line Region of Narrow-Line Seyfert 1 Galaxies

    NASA Astrophysics Data System (ADS)

    Rodríguez-Ardila, A.; Binette, Luc; Pastoriza, Miriani G.; Donzelli, Carlos J.

    2000-08-01

    This work studies the optical emission-line properties and physical conditions of the narrow-line region (NLR) of seven narrow-line Seyfert 1 galaxies (NLS1's) for which high signal-to-noise ratio spectroscopic observations were available. The resolution is 340 km s-1 (at H?) over the wavelength interval 3700-9500 Å, enabling us to separate the broad and narrow components of the permitted emission lines. Our results show that the flux carried out by the narrow component of H? is, on average, 50% of the total line flux. As a result, the [O III] ?5007/H? ratio emitted in the NLR varies from 1 to 5, instead of the universally adopted value of 10. This has strong implications for the required spectral energy distribution that ionizes the NLR gas. Photoionization models that consider a NLR composed of a combination of matter-bounded and ionization-bounded clouds are successful at explaining the low [O III] ?5007/H? ratio and the weakness of low-ionization lines of NLS1's. Variation of the relative proportion of these two type of clouds nicely reproduces the dispersion of narrow-line ratios found among the NLS1 sample. Assuming similar physical model parameters of both NLS1's and the normal Seyfert 1 galaxy NGC 5548, we show that the observed differences of emission-line ratios between these two groups of galaxies can be explained, to a first approximation, in terms of the shape of the input ionizing continuum. Narrow emission-line ratios of NLS1's are better reproduced by a steep power-law continuum in the EUV-soft X-ray region, with spectral index ?~-2. Flatter spectral indices (?~-1.5) match the observed line ratios of NGC 5548 but are unable to provide a good match to the NLS1 ratios. This result is consistent with ROSAT observations of NLS1's, which show that these objects are characterized by steeper power-law indices than those of Seyfert 1 galaxies with strong broad optical lines. Based on observations made at CASLEO. Complejo Astronómico El Leoncito (CASLEO) is operated under agreement between the Consejo Nacional de Investigaciones Científicas y técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juán.

  3. Ultraviolet Spectroscopy of Narrow CMEs

    NASA Astrophysics Data System (ADS)

    Dobrzycka, D.; Raymond, J. C.; Biesecker, D. A.; Li, J.; Ciaravella, A.

    2002-12-01

    Coronal mass ejections (CMEs) are commonly described as new, discrete, bright features appearing in the field of view of a white light coronagraph and moving outward over a period of minutes to hours. Apparent angular widths of the CMEs cover a wide range, from few to 360°. The very narrow structures (narrower than ~15-20°) form only a small subset of all the observed CMEs and are usually referred to as rays, spikes, fans, etc. Recently, Gilbert et al. (2001, ApJ, 550, 1093) reported LASCO white light observations of 15 selected narrow CMEs. We extended the study and analyzed ultraviolet spectroscopy of narrow ejections, including several events listed by Gilbert et al. The data were obtained by the Ultraviolet Coronagraph Spectrometer (UVCS/SOHO). We present comparison of narrow and large CMEs and discuss the relation of the narrow CMEs to coronal jets and/or other narrow transient events. This work is supported by NASA under Grant NAG5-11420 to the Smithsonian Astrophysical Observatory, by the Italian Space Agency and by PRODEX (Swiss contribution).

  4. Inferring middle atmospheric ozone height profiles from ground-based measurements of molecular oxygen emission rates. 2. Comparison with O[sub 2]([sup 1][Delta][sub g])(0,1) band measurements at sunset

    SciTech Connect

    Sica, R.J.; Lowe, R.P. )

    1993-01-20

    The ability to routinely acquire measurements of the ozone density profile in the mesosphere and lower thermosphere is important for use in chemical-dynamical models of the middle atmosphere. Zenith measurements of the O[sub 2]([sup 1][Delta][sub g]) (0,1) band emission rate in the evening twilight were acquired near the spring equinox of 1982 with a Michelson interferometer from London, Ontario, Canada. Knowledge of the change of the O[sub 2]([sup 1][Delta][sub g])(0,1) band emission rate at twilight can be related directly to ozone density, since ozone destruction by sunlight is the primary source of O[sub 2]([sup 1][Delta][sub g]) in the atmosphere. Measurements and calculations have shown that a secondary peak in the ozone density often exists in the middle atmosphere. A model has been developed to infer the ozone profile in the middle atmosphere by simultaneously solving the time-dependent chemistry of the molecular oxygen atmospheric and atmospheric-IR bands and O(ID) during twilight. Calculations are presented which show the effect of a secondary peak in the ozone density at various heights on the O[sub 2]([sup 1][Delta][sub g]) (0,1) band emission rate during twilight. The model is used to demonstrate that the London measurements are consistent with an ozone profile with a secondary peak at 85-90 km. 17 refs., 7 figs.

  5. Zooming into ?-ray loud galactic nuclei: broadband emission and structure dynamics of the blazar PKS 1502+106 and the narrow-line Seyfert 1 1H 0323+342

    NASA Astrophysics Data System (ADS)

    Karamanavis, Vassilis

    2015-05-01

    Blazars are accretion-powered systems representing the most extreme flavor of active galactic nuclei (AGN). This thesis focuses on the study of blazar PKS 1502+106 during a prominent broadband outburst using ultra-high resolution imaging and a broadband single-dish study. The former is accomplished through very-long-baseline interferometry (VLBI) down to short millimeter (mm) wavelengths, while the latter uses densely-sampled radio light curves at a wide frequency range. The same combination allows the detailed study of the galaxy 1H 0323+342. This is a prominent member of the narrow-line Seyfert 1 (NLS1) class of AGN, recently discovered to emit gamma-rays. General aspects of AGN along with an introduction to their discovery, phenomenology, and their constituent parts are discussed in Chapter 1. Here, specific aspects of blazars and concepts used in later chapters are also introduced. Chapter 2 introduces the technique of VLBI from a theoretical standpoint, while in Chapter 3 the practical aspects of VLBI calibration and imaging at mm wavelengths are discussed. The phenomenology and physical characteristics of PKS 1502+106 through a cm- to mm-VLBI study are presented in Chapter 4. The data set features Global Millimeter VLBI Array (GMVA) observations at 7mm (43 GHz) and 3mm (86 GHz) along with complementary observations at 2cm (15 GHz) from the MOJAVE program. We also combine the analysis with F-GAMMA program data at frequencies matching the VLBI monitoring and with the Fermi/LAT gamma-ray light curve. From the rich data set we deduce its kinematical and spectral characteristics which allow the inference of physical parameters of the ultra-relativistic jet of PKS 1502+106. For the jet features identified across observing frequencies we deduce Doppler factors in the range ~10--50 at different positions within the flow. Magnetic field strengths and brightness temperatures along the jet are also deduced. The position-dependent differences in viewing angle and Lorentz factors, indicate a jet bending towards the observer that also accelerates. The kinematical model and radio flux density decomposition into distinct jet components in conjunction with the gamma-ray data indicate that the broadband flare, seen first at ?-rays and its delayed counterparts at radio wavelengths, can be attributed to one traveling jet feature (C3). Finally, the emission site of the gamma-ray emission is constrained to <10--15 pc from the jet base. The outburst of PKS 1502+106 seen through the dense, single-dish, F-GAMMA data set between 2.64--345 GHz is discussed in Chapter 5. By employing three different time series analysis techniques relevant light curve parameters, such as the flare amplitude, flare time scales, and time delays of maxima are extracted. Those exhibit dependencies on observing frequency that are well-described by power laws. The frequency-dependent light curve parameters are compared with the expectations of analytical simulations (see Chapter 5 for references) under the shock-in-jet scenario with which a good agreement is found. From the frequency-dependent time lags, equipartition magnetic field strengths are calculated and in combination with the VLBI findings from Chapter 4, the MeV/GeV emitting region is localized at the edge or slightly further from the bulk of the broad-line region (BLR) material of PKS 1502+106 with important consequences on the origin of photons available for inverse Compton up-scattering. In Chapter 6 the powerful combination of previous findings based on the F-GAMMA monitoring with VLBI images at 15 GHz allows the determination of the viewing angle towards the NLS1 galaxy 1H 0323+342. This is found to be ? =< 12--13 degrees. A summary and concluding remarks arising from the thesis at hand are presented in Chapter 7.

  6. Electronic phases, band gaps, and band overlaps of bismuth antimony nanowires

    E-print Network

    Tang, Shuang

    We have developed an iterative one-dimensional model to study the narrow band gap and the associated nonparabolic dispersion relations for bismuth antimony nanowires. An analytical approximation has also been developed. ...

  7. Quasi-Moseley's law for strong narrow bandwidth soft x-ray sources containing higher charge-state ions

    SciTech Connect

    Ohashi, Hayato Higashiguchi, Takeshi Suzuki, Yuhei; Arai, Goki; Otani, Yukitoshi; Yatagai, Toyohiko; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Jiang, Weihua; Endo, Akira; Sakaue, Hiroyuki A.; Kato, Daiji; Murakami, Izumi; Tamura, Naoki; Sudo, Shigeru; Suzuki, Chihiro; Koike, Fumihiro

    2014-06-09

    Bright narrow band emission observed in optically thin plasmas of high-Z elements in the extreme ultraviolet spectral region follows a quasi-Moseley's law. The peak wavelength can be expressed as ?=(21.86±12.09)×R{sub ?}{sup ?1}×(Z?(23.23±2.87)){sup ?(1.52±0.12)}, where R{sub ?} is the Rydberg constant. The wavelength varies from 13.5?nm to 4.0?nm as the atomic number, Z, increases from Z?=?50 to Z?=?83. The range of emission wavelengths available from hot optically thin plasmas permits the development of bright laboratory-scale sources for applications including x-ray microscopy and x-ray absorption fine structure determination.

  8. Indirect optical absorption and origin of the emission from {beta}-FeSi{sub 2} nanoparticles: Bound exciton (0.809 eV) and band to acceptor impurity (0.795 eV) transitions

    SciTech Connect

    Lang, R.; Amaral, L.

    2010-05-15

    We investigated the optical absorption of the fundamental band edge and the origin of the emission from {beta}-FeSi{sub 2} nanoparticles synthesized by ion-beam-induced epitaxial crystallization of Fe{sup +} implanted SiO{sub 2}/Si(100) followed by thermal annealing. From micro-Raman scattering and transmission electron microscopy measurements it was possible to attest the formation of strained {beta}-FeSi{sub 2} nanoparticles and its structural quality. The optical absorption near the fundamental gap edge of {beta}-FeSi{sub 2} nanoparticles evaluated by spectroscopic ellipsometry showed a step structure characteristic of an indirect fundamental gap material. Photoluminescence spectroscopy measurements at each synthesis stage revealed complex emissions in the 0.7-0.9 eV spectral region, with different intensities and morphologies strongly dependent on thermal treatment temperature. Spectral deconvolution into four transition lines at 0.795, 0.809, 0.851, and 0.873 eV was performed. We concluded that the emission at 0.795 eV may be related to a radiative direct transition from the direct conduction band to an acceptor level and that the emission at 0.809 eV derives from a recombination of an indirect bound exciton to this acceptor level of {beta}-FeSi{sub 2}. Emissions 0.851 and 0.873 eV were confirmed to be typical dislocation-related photoluminescence centers in Si. From the energy balance we determined the fundamental indirect and direct band gap energies to be 0.856 and 0.867 eV, respectively. An illustrative energy band diagram derived from a proposed model to explain the possible transition processes involved is presented.

  9. Bird Banding

    USGS Multimedia Gallery

    Bird Banding - Elizabeth Sellers points out identification characteristics in the plumage of a male common yellowthroat to John P. Mosesso during a capture-recapture study at a Monitoring Avian Productivity and Survivorship (MAPS) program bird banding station....

  10. Surface Emissivity Maps for Use in Satellite Retrievals of Longwave Radiation

    NASA Technical Reports Server (NTRS)

    Wilber, Anne C.; Kratz, David P.; Gupta, Shashi K.

    1999-01-01

    Accurate accounting of surface emissivity is essential for the retrievals of surface temperature from remote sensing measurements, and for the computations of longwave (LW) radiation budget of the Earth?s surface. Past studies of the above topics assumed that emissivity for all surface types, and across the entire LW spectrum is equal to unity. There is strong evidence, however, that emissivity of many surface materials is significantly lower than unity, and varies considerably across the LW spectrum. We have developed global maps of surface emissivity for the broadband LW region, the thermal infrared window region (8-12 micron), and 12 narrow LW spectral bands. The 17 surface types defined by the International Geosphere Biosphere Programme (IGBP) were adopted as such, and an additional (18th) surface type was introduced to represent tundra-like surfaces. Laboratory measurements of spectral reflectances of 10 different surface materials were converted to corresponding emissivities. The 10 surface materials were then associated with 18 surface types. Emissivities for the 18 surface types were first computed for each of the 12 narrow spectral bands. Emissivities for the broadband and the window region were then constituted from the spectral band values by weighting them with Planck function energy distribution.

  11. Multi-photon excited coherent random laser emission in ZnO powders

    NASA Astrophysics Data System (ADS)

    Tolentino Dominguez, Christian; Gomes, Maria De A.; Macedo, Zélia S.; de Araújo, Cid B.; Gomes, Anderson S. L.

    2014-11-01

    We report the observation and analysis of anti-Stokes coherent random laser (RL) emission from zinc oxide (ZnO) powders excited by one-, two- or three-photon femtosecond laser radiation. The ZnO powders were produced via a novel proteic sol-gel, low-cost and environmentally friendly route using coconut water in the polymerization step of the metal precursor. One- and two-photon excitation at 354 nm and 710 nm, respectively, generated single-band emissions centred at about 387 nm. For three-photon excitation, the emission spectra showed a strong ultraviolet (UV) band (380-396 nm) attributed to direct three-photon absorption from the valence band to the conduction band. The presence of an intensity threshold and a bandwidth narrowing of the UV band from about 20 to 4 nm are clear evidence of RL action. The observation of multiple sub-nanometre narrow peaks in the emission spectra for excitation above the RL threshold is consistent with random lasing by coherent feedback.

  12. L-band sea surface emissivity: Preliminary results of the WISE-2000 campaign and its application to salinity retrieval in the SMOS mission

    NASA Astrophysics Data System (ADS)

    Camps, A.; Corbella, I.; Vall-Llossera, M.; Duffo, N.; Torres, F.; Villarino, R.; Enrique, L.; Miranda, J.; Julbé, F.; Font, J.; Juliã, A.; Gabarró, C.; Etchetto, J.; Boutin, J.; Weill, A.; Caselles, V.; Rubio, E.; Wursteisen, P.; Berger, M.; MartíN-Neira, M.

    2003-08-01

    Soil moisture and ocean salinity at surface level can be measured by passive microwave remote sensing at L-band. To provide global coverage data of soil moisture and ocean salinity with three-day revisit time, the Earth Explorer Opportunity Mission SMOS (Soil Moisture and Ocean Salinity) was selected by ESA (European Space Agency) in May 1999. SMOS' single payload is a Y-shaped 2-D aperture synthesis interferometric radiometer called MIRAS (Microwave Imaging Radiometer by Aperture Synthesis). SMOS presents some particular imaging peculiarities: variation of incidence and azimuth angles, different radiometric sensitivity and accuracy at each direction (pixels), and geometric polarization mixing. Therefore, the accuracy of the geophysical parameter retrieval depends on the knowledge of the angular dependence of the emissivity over a wide range of incidence and azimuth angles. The accuracy of the sea surface salinity retrievals depends on our capability to correct the wind-induced variation of the brightness temperatures. To better understand wind effects, ESA sponsored the WInd and Salinity Experiment 2000 (WISE-2000) from November 15, 2000, to January 16, 2001, in the Casablanca oil rig, at 40 km off the coast of Tarragona (Spain). This paper is divided into two parts. First, it presents the derived sensitivities of the brightness temperatures at vertical and horizontal polarizations with wind speed, and compares to Hollinger's measurements and numerical simulations. Second, these results are applied to the SMOS sea surface salinity (SSS) retrieval problem for different tracks within the swath. It is shown that, except for low SSS and sea surface temperature (SST), the retrieved SSS has a RMS error of approximately 1 psu in one satellite pass.

  13. Silicon nanowire band gap modification.

    PubMed

    Nolan, Michael; O'Callaghan, Sean; Fagas, Giorgos; Greer, James C; Frauenheim, Thomas

    2007-01-01

    Band gap modification for small-diameter (approximately 1 nm) silicon nanowires resulting from the use of different species for surface termination is investigated by density functional theory calculations. Because of quantum confinement, small-diameter wires exhibit a direct band gap that increases as the wire diameter narrows, irrespective of surface termination. This effect has been observed in previous experimental and theoretical studies for hydrogenated wires. For a fixed cross-section, the functional group used to saturate the silicon surface significantly modifies the band gap, resulting in relative energy shifts of up to an electronvolt. The band gap shifts are traced to details of the hybridization between the silicon valence band and the frontier orbitals of the terminating group, which is in competition with quantum confinement. PMID:17212436

  14. Effectiveness of Near-Grazing Incidence Reflection in Creating the Rotationally Modulated Lanes in the Jovian Hectometric Radio Emission Spectrum

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Gurnett, D. A.; Kurth, W. S.; Groene, J. B.

    1999-01-01

    The Galileo plasma wave instrument has identified a narrow (in frequency) attenuation band in the hectometric emission that varies in frequency with system 3 longitude. It is possible to model this emission band assuming a high-latitude cyclotron source region with emission that is efficiently attenuated when the ray path is nearly tangent to an L shell that is close to the Io flux tube. The data suggest that the mechanism for attenuating the emission is very efficient, with the ratio of attenuated to unattenuated emission I/I(sub o) < 0.02, and not a strong function of frequency. In this paper we demonstrate that incoherent scattering alone cannot explain the attenuation lane, which does not preclude coherent scattering by uncertain processes. We find rather that the source of attenuation is consistent with near-grazing incidence reflection of emission from an L shell that is near the Io flux tube (a caustic surface).

  15. Early Experience & Multisensory Perceptual Narrowing

    PubMed Central

    Lewkowicz, David J.

    2014-01-01

    Perceptual narrowing is a reflection of early experience and contributes in key ways to perceptual and cognitive development. In general, findings have shown that unisensory perceptual sensitivity in early infancy is broadly tuned such that young infants respond to, and discriminate, native as well as non-native sensory inputs, whereas older infants only respond to native inputs. Recently, my colleagues and I discovered that perceptual narrowing occurs at the multisensory processing level as well. The present article reviews this new evidence and puts it in the larger context of multisensory perceptual development and the role that perceptual experience plays in it. Together, the evidence on unisensory and multisensory narrowing shows that early experience shapes the emergence of perceptual specialization and expertise. PMID:24435505

  16. Anisotropic ionizing radiation in Seyfert galaxies. I - The extended narrow-line region in Markarian 573

    NASA Technical Reports Server (NTRS)

    Tsvetanov, Zlatan; Walsh, J. R.

    1992-01-01

    The morphology, kinematics, and ionization state of the nuclear extended narrow-line region (ENLR) of the Seyfert 2 galaxy Mrk 573 are studied using narrow-band images of a grid of long-slit spectra. The entire ENLR is mapped spectroscopically, and velocity structure is studied. The velocity field map shows a typical galactic rotation picture with some important deviations. A simple geometric model, in accordance with the 'unified schemes', is employed to study the effects of various parameters of the observed picture. The best match is achieved when a biconical radiation field illuminates the ISM of the host galaxy that takes part in a normal galaxy rotation but also has radial motions close to the nucleus. The emission-line images reveal an ENLR elongated along the radio axis in the northwest-southeast direction, but a map of the flux ratio forbidden O III 5007/(H-alpha + forbidden N II) shows a different structure, with the highest excitation peak offset by about 4 arcsec along the radio axis to the southeast.

  17. The Suzaku Observation of NGC 3516: Complex Absorption and the Broad and Narrow Fe K Lines

    NASA Technical Reports Server (NTRS)

    Markowitz, Alex; Reeves, James N.; Miniutti, Giovanni; Serlemitsos, Peter; Kunieda, Hideyo; Taqoob, Tahir; Fabian, Andrew C.; Fukazawa, Yasushi; Mushotzky, Richard; Okajima, Takashi; Gallo, Luigi; Awaki, Hisamitsu; Griffiths, Richard E.

    2007-01-01

    We present results from a 150 ksec Suzaku observation of the Seyfert 1 NGC 3516 in October 2005. The source was in a relatively highly absorbed state. Our best-fit model is consistent with partial covering by a lowly-ionized absorber with a column density near 5x10(exp 22) cm(exp -2) and with a covering fraction 96-100 percent. Narrow K-shell absorption features due to He- and H-like Fe confirm the presence of a high-ionization absorbing component as well. A broad Fe K(alpha) diskline is required in all fits, even after the complex absorption is taken into account; an additional partial-covering component is an inadequate substitute for the continuum curvature associated with the broad line. The narrow Fe Ka line at 6.4 keV is resolved, yielding a velocity width commensurate with the optical Broad Line Region. The strength of the Compton reflection hump suggests a contribution mainly from the broad Fe line origin. We include in our model soft band emission lines from He- and H-like ions and radiative recombination lines, consistent with photo-ionization, though a small contribution from collisional ionization is possible.

  18. Band gap effects of hexagonal boron nitride using oxygen plasma

    SciTech Connect

    Sevak Singh, Ram; Leong Chow, Wai; Yingjie Tay, Roland; Hon Tsang, Siu; Mallick, Govind; Tong Teo, Edwin Hang

    2014-04-21

    Tuning of band gap of hexagonal boron nitride (h-BN) has been a challenging problem due to its inherent chemical stability and inertness. In this work, we report the changes in band gaps in a few layers of chemical vapor deposition processed as-grown h-BN using a simple oxygen plasma treatment. Optical absorption spectra show a trend of band gap narrowing monotonically from 6?eV of pristine h-BN to 4.31?eV when exposed to oxygen plasma for 12?s. The narrowing of band gap causes the reduction in electrical resistance by ?100 fold. The x-ray photoelectron spectroscopy results of plasma treated hexagonal boron nitride surface show the predominant doping of oxygen for the nitrogen vacancy. Energy sub-band formations inside the band gap of h-BN, due to the incorporation of oxygen dopants, cause a red shift in absorption edge corresponding to the band gap narrowing.

  19. Temperature measurements via narrow line laser absorption of carbon dioxide

    SciTech Connect

    Wooldridge, M.S.

    1996-12-31

    Theoretical development for temperature measurements via narrow line, infrared absorption of carbon dioxide (CO{sub 2}) is presented. The proposed technique is based on rapid-scanning of two adjacent absorption line shapes. Spectroscopic considerations for sensitivity to temperature measurements are discussed. Several line pairs are evaluated, and the R(58) and R(60) transitions of the (00{sup 0}1){l_arrow}(00{sup 0}0) band are suggested for use in high temperature measurements for combustion systems.

  20. Mechanism of two types of Na emission observed in sonoluminescence

    NASA Astrophysics Data System (ADS)

    Nakajima, Ryota; Hayashi, Yuichi; Choi, Pak-Kon

    2015-07-01

    The sonoluminescence (SL) spectrum of Na atoms revealed that the Na line consists of two components, one of which is a broadened component (broad component) which is shifted from the original D lines, and the other is an unshifted narrow component (narrow component). We spatially separated the continuum, broad, and narrow components by capturing SL images using different optical filters. We also temporally separated these components by measuring SL pulses using respective band-pass filters. The SL image distribution and the timing of the SL pulses were different between the broad and narrow components. The results suggested that the broad and narrow components of Na emission are generated from different bubble populations. The dependences of SL spectra on ultrasonic frequency and dissolved rare gas (He, Ne, Ar, Kr, and Xe) were also investigated. It is concluded that the broad component and a blue satellite peak at 558 nm originate from van der Waals molecules composed of Na and rare-gas atoms. The narrow component was predicted to occur under temperature conditions at bubble collapse higher than that for the broad component.

  1. Pulse stretcher for narrow pulses

    NASA Technical Reports Server (NTRS)

    Lindsey, R. S., Jr. (inventor)

    1974-01-01

    A pulse stretcher for narrow pulses is presented. The stretcher is composed of an analog section for processing each arriving analog pulse and a digital section with logic for providing command signals to the gates and switches in the analog section.

  2. XMM observations of the narrow-line QSO PHL 1092: Detection of a high and variable soft component

    E-print Network

    Surajit Dasgupta; A. R. Rao; G. C. Dewangan

    2004-08-18

    We present results based on an XMM-Newton observation of the high luminosity narrow-line QSO PHL 1092 performed in 2003 January. The 0.3 - 10 keV spectrum is well described by a model which includes a power-law (Gamma ~ 2.1) and two blackbody components (kT ~ 130 eV and kT ~ 50 eV). The soft X-ray excess emission is featureless and contributes ~ 80% to the total X-ray emission in the 0.3 - 10 keV band. The most remarkable feature of the present observation is the detection of X-ray variability at very short time scale: the X-ray emission varied by 35% in about 5000 s. We find that this variability can be explained by assuming that only the overall normalization varied during the observation. There was no evidence for any short term spectral variability and the spectral shape was similar even during the ASCA observation carried out in 1997. Considering the high intrinsic luminosity (~ 2x10^45 erg/s) and the large inferred mass of the putative black hole (~ 1.6x10^8 M_sun), the observed time scale of variability indicates emission at close to Eddington luminosity arising from very close to the black hole. We suggest that PHL 1092 in particular (and narrow line Seyfert galaxies in general) is a fast rotating black hole emitting close to its Eddington luminosity and the X-ray emission corresponds to the high-soft state seen in Galactic black hole sources.

  3. MULTIWAVELENGTH MONITORING OF THE ENIGMATIC NARROW-LINE SEYFERT 1 PMN J0948+0022 IN 2009 MARCH-JULY

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Bloom, E. D.; Borgland, A. W.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Bastieri, D.; Baughman, B. M.; Bonamente, E.; Brigida, M.; Bruel, P.

    2009-12-10

    Following the recent discovery of gamma rays from the radio-loud narrow-line Seyfert 1 galaxy PMN J0948+0022 (z = 0.5846), we started a multiwavelength campaign from radio to gamma rays, which was carried out between the end of 2009 March and the beginning of July. The source displayed activity at all the observed wavelengths: a general decreasing trend from optical to gamma-ray frequencies was followed by an increase of radio emission after less than two months from the peak of the gamma-ray emission. The largest flux change, about a factor of about 4, occurred in the X-ray band. The smallest was at ultraviolet and near-infrared frequencies, where the rate of the detected photons dropped by a factor 1.6-1.9. At optical wavelengths, where the sampling rate was the highest, it was possible to observe day scale variability, with flux variations up to a factor of about 3. The behavior of PMN J0948+0022 observed in this campaign and the calculated power carried out by its jet in the form of protons, electrons, radiation, and magnetic field are quite similar to that of blazars, specifically of flat-spectrum radio quasars. These results confirm the idea that radio-loud narrow-line Seyfert 1 galaxies host relativistic jets with power similar to that of average blazars.

  4. Multiwavelength Monitoring of the Enigmatic Narrow-Line Seyfert 1 PMN J0948 0022 in March-July 2009

    SciTech Connect

    Abdo, A.A.; Ackermann, M.; Ajello, M.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B.M.; Bechtol, K.; Bellazzini, R. Berenji, B.; Bloom, E.D.; Bonamente, E. Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T.H.; Caliandro, G.A.; /more authors..

    2012-03-29

    Following the recent discovery of {gamma} rays from the radio-loud narrow-line Seyfert 1 galaxy PMN J0948+0022 (z = 0.5846), we started a multiwavelength campaign from radio to {gamma} rays, which was carried out between the end of 2009 March and the beginning of July. The source displayed activity at all the observed wavelengths: a general decreasing trend from optical to {gamma}-ray frequencies was followed by an increase of radio emission after less than two months from the peak of the {gamma}-ray emission. The largest flux change, about a factor of about 4, occurred in the X-ray band. The smallest was at ultraviolet and near-infrared frequencies, where the rate of the detected photons dropped by a factor 1.6-1.9. At optical wavelengths, where the sampling rate was the highest, it was possible to observe day scale variability, with flux variations up to a factor of about 3. The behavior of PMN J0948+0022 observed in this campaign and the calculated power carried out by its jet in the form of protons, electrons, radiation, and magnetic field are quite similar to that of blazars, specifically of flat-spectrum radio quasars. These results confirm the idea that radio-loud narrow-line Seyfert 1 galaxies host relativistic jets with power similar to that of average blazars.

  5. Multiwavelength Monitoring of the Enigmatic Narrow-Line Seyfert 1 PMN J0948+0022 in 2009 March-July

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T. H.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cavazzuti, E.; Cecchi, C.; Çelik, Ö.; Celotti, A.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Collmar, W.; Conrad, J.; Costamante, L.; Cutini, S.; de Angelis, A.; de Palma, F.; Silva, E. Do Couto e.; Drell, P. S.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Fortin, P.; Foschini, L.; Frailis, M.; Fuhrmann, L.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Hays, E.; Hughes, R. E.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kadler, M.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocian, M. L.; Kuss, M.; Lande, J.; Latronico, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Makeev, A.; Max-Moerbeck, W.; Mazziotta, M. N.; McConville, W.; McEnery, J. E.; McGlynn, S.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Nestoras, I.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Parent, D.; Pavlidou, V.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Readhead, A.; Reimer, O.; Reposeur, T.; Richards, J. L.; Rodriguez, A. Y.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sanchez, D.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Sgrò, C.; Shaw, M. S.; Smith, P. D.; Spandre, G.; Spinelli, P.; Strickman, M. S.; Suson, D. J.; Tagliaferri, G.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Tibolla, O.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Usher, T. L.; Vasileiou, V.; Vilchez, N.; Vitale, V.; Waite, A. P.; Wang, P.; Wehrle, A. E.; Winer, B. L.; Wood, K. S.; Ylinen, T.; Zensus, J. A.; Ziegler, M.; Fermi/LAT Collaboration; Angelakis, E.; Bailyn, C.; Bignall, H.; Blanchard, J.; Bonning, E. W.; Buxton, M.; Canterna, R.; Carramiñana, A.; Carrasco, L.; Colomer, F.; Doi, A.; Ghisellini, G.; Hauser, M.; Hong, X.; Isler, J.; Kino, M.; Kovalev, Y. Y.; Kovalev, Yu. A.; Krichbaum, T. P.; Kutyrev, A.; Lahteenmaki, A.; van Langevelde, H. J.; Lister, M. L.; Macomb, D.; Maraschi, L.; Marchili, N.; Nagai, H.; Paragi, Z.; Phillips, C.; Pushkarev, A. B.; Recillas, E.; Roming, P.; Sekido, M.; Stark, M. A.; Szomoru, A.; Tammi, J.; Tavecchio, F.; Tornikoski, M.; Tzioumis, A. K.; Urry, C. M.; Wagner, S.

    2009-12-01

    Following the recent discovery of ? rays from the radio-loud narrow-line Seyfert 1 galaxy PMN J0948+0022 (z = 0.5846), we started a multiwavelength campaign from radio to ? rays, which was carried out between the end of 2009 March and the beginning of July. The source displayed activity at all the observed wavelengths: a general decreasing trend from optical to ?-ray frequencies was followed by an increase of radio emission after less than two months from the peak of the ?-ray emission. The largest flux change, about a factor of about 4, occurred in the X-ray band. The smallest was at ultraviolet and near-infrared frequencies, where the rate of the detected photons dropped by a factor 1.6-1.9. At optical wavelengths, where the sampling rate was the highest, it was possible to observe day scale variability, with flux variations up to a factor of about 3. The behavior of PMN J0948+0022 observed in this campaign and the calculated power carried out by its jet in the form of protons, electrons, radiation, and magnetic field are quite similar to that of blazars, specifically of flat-spectrum radio quasars. These results confirm the idea that radio-loud narrow-line Seyfert 1 galaxies host relativistic jets with power similar to that of average blazars.

  6. Systematic Study of Electronic Phases, Band Gaps and Band Overlaps of Bismuth Antimony Nanowires

    E-print Network

    Shuang Tang; Mildred Dresselhaus

    2013-12-03

    We have developed an iterative one dimensional model to study the narrow band-gap and the associated non-parabolic dispersion relations for bismuth antimony nanowires. An analytical approximation has also been developed. Based on the general model, we have developed, we have calculated and analyzed the electronic phase diagrams and the band-gap/band-overlap map for bismuth antimony nanowires, as a function of stoichiometry, growth orientation, and wire width.

  7. An amphidynamic inorganic-organic hybrid crystal of bromoplumbate with 1,5-bis(1-methylimidazolium)pentane exhibiting multi-functionality of a dielectric anomaly and temperature-dependent dual band emissions.

    PubMed

    Tong, Yuan-Bo; Ren, Li-Te; Duan, Hai-Bao; Liu, Jian-Lan; Ren, Xiao-Ming

    2015-10-28

    Organic-inorganic hybrid crystals, [1,5-bis(1-methylimidazolium)pentane][PbBr3]2 (1), were achieved through the mutual diffusion of a bi-imidazolium based ionic liquid and PbBr2 solution of DMF in a glass tube. The hybrid solid crystallizes in the orthorhombic space group Fdd2 at room temperature; and is composed of one-dimensional [PbBr3]? chains where the neighbouring PbBr6 coordination octahedra are linked together via the face-sharing mode and the inorganic chains are surrounded by organic cations. The hybrid solid exhibits a dielectric anomaly around 443 K and dielectric relaxation above 400 K, the dielectric response mechanism was investigated using variable-temperature X-ray single crystal and powder diffraction as well as DSC techniques. Fascinatingly, this hybrid solid shows dual band emissions, moreover, the fluorescence nature of the two emission bands exhibits a distinct response to temperature, leading to a temperature-dependent fluorescence color, this feature has promising application in the emission temperature-sensing field. PMID:26399984

  8. Fermi level stabilization and band edge energies in Cd{sub x}Zn{sub 1?x}O alloys

    SciTech Connect

    Detert, Douglas M.; Tom, Kyle B.; Dubon, Oscar D.; Battaglia, Corsin; Javey, Ali; Denlinger, Jonathan D.; Lim, Sunnie H. N.; Anders, André; Yu, Kin M.; Walukiewicz, Wladek

    2014-06-21

    We have measured the band edge energies of Cd{sub x}Zn{sub 1?x}O thin films as a function of composition by three independent techniques: we determine the Fermi level stabilization energy by pinning the Fermi level with ion irradiation, measure the binding energy of valence band states and core levels by X-ray photoelectron spectroscopy, and probe shifts in the conduction band and valence band density of states using soft X-ray absorption and emission spectroscopy, respectively. The three techniques find consensus in explaining the origin of compositional trends in the optical-bandgap narrowing upon Cd incorporation in wurtzite ZnO and widening upon Zn incorporation in rocksalt CdO. The conduction band minimum is found to be stationary for both wurtzite and rocksalt alloys, and a significant upward rise of the valence band maximum accounts for the majority of these observed bandgap changes. Given these band alignments, alloy disorder scattering is found to play a negligible role in decreasing the electron mobility for all alloys. These band alignment details, combined with the unique optical and electrical properties of the two phase regimes, make CdZnO alloys attractive candidates for photoelectrochemical water splitting applications.

  9. BandPass Sigma-Delta Modulator for wideband IF signals May 20, 1999 1 BandPass Sigma-Delta

    E-print Network

    Daniel, Luca

    BandPass Sigma-Delta Modulator for wideband IF signals May 20, 1999 1 BandPass Sigma-Delta (STMicroelectronics Berkeley Labs) 1.0 Abstract In this project, a design for a BandPass Sigma-Delta modulator.0 Introduction Sigma-Delta modulation techniques have been applied to narrow-band passband signals [Jantzi93

  10. Band models and correlations for infrared radiation

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.

    1975-01-01

    Absorption of infrared radiation by various line and band models are briefly reviewed. Narrow band model relations for absorptance are used to develop 'exact' formulations for total absorption by four wide band models. Application of a wide band model to a particular gas largely depends upon the spectroscopic characteristic of the absorbing-emitting molecule. Seven continuous correlations for the absorption of a wide band model are presented and each one of these is compared with the exact (numerical) solutions of the wide band models. Comparison of these results indicate the validity of a correlation for a particular radiative transfer application. In radiative transfer analyses, use of continuous correlations for total band absorptance provides flexibilities in various mathematical operations.

  11. An XMM-Newton Study of the Bright Ultrasoft Narrow-Line Quasar NAB 0205+024

    NASA Technical Reports Server (NTRS)

    Brandt, Niel

    2004-01-01

    The broad-band X-ray continuum of NAB 0205424 is well constrained due to the excellent photon statistics obtained (about 97,700 counts), and its impressive soft X-ray excess is clearly apparent. The hard X-ray power law has become notably steeper than when NAB 0205424 was observed with ASCA, attesting to the presence of significant X-ray spectral variability. A strong and broad emission feature is detected from about 5 to 6.4 keV, and we have modeled this as a relativistic line emitted close to the black hole from a narrow annulus of the accretion disk. Furthermore, a strong X-ray flare is detected with a hard X-ray spectrum; this flare may be responsible for illuminating the inner line-emitting part of the accretion disk. The combined observational results can be broadly interpreted in terms of the "thundercloud model proposed by Merloni & Fabian (2001).

  12. Inter-band optoelectronic properties in quantum dot structure of low band gap III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Dey, Anup; Maiti, Biswajit; Chanda Sarkar, Debasree

    2014-04-01

    A generalized theory is developed to study inter-band optical absorption coefficient (IOAC) and material gain (MG) in quantum dot structures of narrow gap III-V compound semiconductor considering the wave-vector (k?) dependence of the optical transition matrix element. The band structures of these low band gap semiconducting materials with sufficiently separated split-off valance band are frequently described by the three energy band model of Kane. This has been adopted for analysis of the IOAC and MG taking InAs, InSb, Hg1-xCdxTe, and In1-xGaxAsyP1-y lattice matched to InP, as example of III-V compound semiconductors, having varied split-off energy band compared to their bulk band gap energy. It has been found that magnitude of the IOAC for quantum dots increases with increasing incident photon energy and the lines of absorption are more closely spaced in the three band model of Kane than those with parabolic energy band approximations reflecting the direct the influence of energy band parameters. The results show a significant deviation to the MG spectrum of narrow-gap materials having band nonparabolicity compared to the parabolic band model approximations. The results reflect the important role of valence band split-off energies in these narrow gap semiconductors.

  13. Inter-band optoelectronic properties in quantum dot structure of low band gap III-V semiconductors

    SciTech Connect

    Dey, Anup; Maiti, Biswajit; Chanda, Debasree

    2014-04-14

    A generalized theory is developed to study inter-band optical absorption coefficient (IOAC) and material gain (MG) in quantum dot structures of narrow gap III-V compound semiconductor considering the wave-vector (k{sup ?}) dependence of the optical transition matrix element. The band structures of these low band gap semiconducting materials with sufficiently separated split-off valance band are frequently described by the three energy band model of Kane. This has been adopted for analysis of the IOAC and MG taking InAs, InSb, Hg{sub 1?x}Cd{sub x}Te, and In{sub 1?x}Ga{sub x}As{sub y}P{sub 1?y} lattice matched to InP, as example of III–V compound semiconductors, having varied split-off energy band compared to their bulk band gap energy. It has been found that magnitude of the IOAC for quantum dots increases with increasing incident photon energy and the lines of absorption are more closely spaced in the three band model of Kane than those with parabolic energy band approximations reflecting the direct the influence of energy band parameters. The results show a significant deviation to the MG spectrum of narrow-gap materials having band nonparabolicity compared to the parabolic band model approximations. The results reflect the important role of valence band split-off energies in these narrow gap semiconductors.

  14. Terrestrial structured radio emissions occurring close to the equatorial regions

    NASA Astrophysics Data System (ADS)

    Boudjada, Mohammed Y.; Galopeau, Patrick H. M.; Sawas, Sami; Berthelier, Jean-Jacques

    2015-04-01

    We study the occurrence of terrestrial radio emissions observed by the electric field experiment (ICE) onboard DEMETER micro-satellite. We principally consider the ICE observations recorded in the HF frequency range between 10 kHz and 3.175 MHz. A dynamic spectrum is recorded each half-orbit with a time and frequency resolutions, respectively, in the order of 3.25 kHz and 2.048 sec. The terrestrial structured radio emission is found to occur when the satellite is approaching the equatorial region of the Earth. It appears as a structured narrow band 'continuum' with a positive or negative low frequency drift rate, less than 1 kHz/s. The bandwidth is, on average, of about 30 kHz. We derive from our investigation the beam and the probable location of the emission source. We discuss the origin of this terrestrial radio emission and its dependence, or not, on the solar and geomagnetic activities.

  15. The peculiar radio-loud narrow line Seyfert 1 galaxy 1H 0323+342

    SciTech Connect

    Paliya, Vaidehi S.; Stalin, C. S.; Sahayanathan, S.; Parker, M. L.; Fabian, A. C.; Anjum, Ayesha; Pandey, S. B.

    2014-07-10

    We present a multiwavelength study of the radio-loud narrow-line Seyfert 1 galaxy (NLSy1) 1H 0323+342, detected by the Fermi Gamma-Ray Space Telescope. Multiband light curves show many orphan X-ray and optical flares having no corresponding ?-ray counterparts. Such anomalous variability behavior can be due to different locations of the emission region from the central source. During a large flare, a ?-ray flux doubling timescale as small as ?3 hr is noticed. We built spectral energy distributions (SEDs) during different activity states and modeled them using a one-zone leptonic model. The shape of the optical/UV component of the SEDs is dominated by accretion disk emission in all the activity states. In the X-ray band, significant thermal emission from the hot corona is inferred during quiescent and first flaring states; however, during subsequent flares, the nonthermal jet component dominates. The ?-ray emission in all the states can be well explained by inverse-Compton scattering of accretion disk photons reprocessed by the broad-line region. The source showed violent intra-night optical variability, coinciding with one of the high ?-ray activity states. An analysis of the overall X-ray spectrum fitted with an absorbed power-law plus relativistic reflection component hints at the presence of an Fe K? line and returns a high black hole spin value of a = 0.96 ± 0.14. We argue that 1H 0323+342 possesses dual characteristics, akin to both flat-spectrum radio quasars (FSRQs) and radio-quiet NLSy1 galaxies, though at a low jet power regime compared to powerful FSRQs.

  16. ISOCAM Photometry of Narrow-Line X-ray Galaxies

    E-print Network

    J. D. Law-Green; A. Zezas; M. J. Ward; C. Boisson

    1998-12-23

    Mid-infrared photometry of the hosts of Narrow-Line X-ray Galaxies at 6 microns and 12 microns has been attempted with ISOCAM. No conclusive detections have been made. This implies that these are quiescent objects with little or no active star-formation. Neither X-ray binaries nor starburst-driven superwinds are consistent explanations for the X-ray emission in these objects. We conclude that these NLXGs are predominantly AGN-powered.

  17. Narrow spectral peaks in electrons precipitating from the slot region

    NASA Technical Reports Server (NTRS)

    Imhof, W. L.; Reagan, J. B.; Gaines, E. E.; Anderson, R. R.

    1983-01-01

    Narrow L-dependent peaks commonly occur in the energy spectra of electrons precipitating from the inner radiation belt at L approximately equal to 1.5-1.85, and the cause of the peaks has been attributed to cyclotron resonance interactions with waves generated by VLF transmitters. In the slot region, L-dependent peaks have also been reported at L approximately equal to 2-3.5, but these have been predominately wider and consistent with their origin being cyclotron resonance interactions involving naturally occurring hiss. The infrequent occurrence of narrow peaks in electrons precipitating at L greater than or approximately equal to 2 is investigated. From coordinated wave and plasma density measurements it is found that if the narrow peaks are formed by first-order cyclotron resonant interactions occurring close to the magnetic equator between narrow band waves and the trapped electron population, then the equatorial plasma density gradients are unusually steep. This finding is consistent with the evidence previously obtained by other techniques for structured plasma density profiles in that L shell region of space.

  18. Doppler Broadening of Diffuse Interstellar Bands

    NASA Astrophysics Data System (ADS)

    B?czek, K.; Wszo?ek, B.

    2008-12-01

    For few dozens of hot reddened stars we have measured half widths (HW) and equivalent widths (EW) of the interstellar sodium D2 line and of the narrow and relatively strong diffuse interstellar band at 6196 Å. We have searched for mutual correlations between intensities of the both lines and we found that the width of the considered diffuse band does not follow the corresponding width for D2 line.

  19. Lyman-alpha emission from the Lyman-alpha forest. [in high red shift quasar spectra due to molecular clouds

    NASA Technical Reports Server (NTRS)

    Hogan, Craig J.; Weymann, Ray J.

    1987-01-01

    It is suggested that high-dispersion long-slit spectra or very narrow-band etalon images of 'blank' sky could reveal patches of Ly-alpha line emission from the population of clouds whose absorption produces the 'Ly-alpha forest' in QSO spectra. A nonobservation can put limits on the ionizing background at high redshift which are better than those obtainable by direct measurements of background light.

  20. New Limits on Gamma-Ray Emission from Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Griffin, Rhiannon D.; Dai, Xinyu; Kochanek, Christopher S.

    2014-11-01

    Galaxy clusters are predicted to produce ?-rays through cosmic ray interactions and/or dark matter annihilation, potentially detectable by the Fermi Large Area Telescope (Fermi-LAT). We present a new, independent stacking analysis of Fermi-LAT photon count maps using the 78 richest nearby clusters (z < 0.12) from the Two Micron All Sky Survey cluster catalog. We obtain the lowest limit on the photon flux to date, 2.3 × 10-11 photons cm-2 s-1 (95% confidence) per cluster in the 0.8-100 GeV band, which corresponds to a luminosity limit of 3.5 × 1044 photons s-1. We also constrain the emission limits in a range of narrower energy bands. Scaling to recent cosmic ray acceleration and ?-ray emission models, we find that cosmic rays represent a negligible contribution to the intra-cluster energy density and gas pressure.

  1. NEW LIMITS ON GAMMA-RAY EMISSION FROM GALAXY CLUSTERS

    SciTech Connect

    Griffin, Rhiannon D.; Dai, Xinyu; Kochanek, Christopher S. E-mail: xdai@ou.edu

    2014-11-01

    Galaxy clusters are predicted to produce ?-rays through cosmic ray interactions and/or dark matter annihilation, potentially detectable by the Fermi Large Area Telescope (Fermi-LAT). We present a new, independent stacking analysis of Fermi-LAT photon count maps using the 78 richest nearby clusters (z < 0.12) from the Two Micron All Sky Survey cluster catalog. We obtain the lowest limit on the photon flux to date, 2.3 × 10{sup –11} photons cm{sup –2} s{sup –1} (95% confidence) per cluster in the 0.8-100 GeV band, which corresponds to a luminosity limit of 3.5 × 10{sup 44} photons s{sup –1}. We also constrain the emission limits in a range of narrower energy bands. Scaling to recent cosmic ray acceleration and ?-ray emission models, we find that cosmic rays represent a negligible contribution to the intra-cluster energy density and gas pressure.

  2. Band Together!

    ERIC Educational Resources Information Center

    Olson, Cathy Applefeld

    2011-01-01

    After nearly a decade as band director at St. James High School in St. James, Missouri, Derek Limback knows that the key to building a successful program is putting the program itself above everything else. Limback strives to augment not only his students' musical prowess, but also their leadership skills. Key to his philosophy is instilling a…

  3. Energy dependence of the band-limited noise in black hole X-ray binaries?

    NASA Astrophysics Data System (ADS)

    Stiele, H.; Yu, W.

    2015-10-01

    Black hole low-mass X-ray binaries show a variety of variability features, which manifest as narrow peak-like structures superposed on broad noise components in power density spectra in the hard X-ray emission. In this work, we study variability properties of the band-limited noise component during the low-hard state for a sample of black hole X-ray binaries. We investigate the characteristic frequency and amplitude of the band-limited noise component and study covariance spectra. For observations that show a noise component with a characteristic frequency above 1 Hz in the hard energy band (4-8 keV), we found this very same component at a lower frequency in the soft band (1-2 keV). This difference in characteristic frequency is an indication that while both the soft and the hard band photons contribute to the same band-limited noise component, which likely represents the modulation of the mass accretion rate, the origin of the soft photons is actually further away from the black hole than the hard photons. Thus, the soft photons are characterized by larger radii, lower frequencies and softer energies, and are probably associated with a smaller optical depth for Comptonization up-scattering from the outer layer of the corona, or suggest a temperature gradient of the corona. We interpret this energy dependence within the picture of energy-dependent power density states as a hint that the contribution of the up-scattered photons originating in the outskirts of the Comptonizing corona to the overall emission in the soft band is becoming significant.

  4. Propane absorption band intensities and band model parameters from 680 to 1580/cm at 296 and 200 K

    NASA Technical Reports Server (NTRS)

    Giver, L. P.; Valero, F. P. J.; Varanasi, P.

    1984-01-01

    Band intensities and profiles have been measured for the propane absorption bands from 680 to 1580/cm at 296 and 200 K. This work was stimulated by the discovery of several propane bands in the spectrum of Titan by the Voyager 1 spacecraft. The low temperature laboratory data show that the bands become narrower and the Q branches of the bands somewhat stronger than they are at room temperature. Random band model parameters were determined over the entire region from the 42 spectra obtained at room temperature.

  5. Triple-doped KMnF3:Yb(3+)/Er(3+)/Tm(3+) nanocubes: four-color upconversion emissions with strong red and near-infrared bands.

    PubMed

    Wang, Hao; Hong, Xiaodong; Han, Renlu; Shi, Junhui; Liu, Zongjun; Liu, Shujuan; Wang, You; Gan, Yang

    2015-01-01

    Triple-doped (Yb(3+)/Er(3+)/Tm(3+)) KMnF3 nanocubes with uniform sizes of 250?nm were synthesized by a facile hydrothermal route using the oleic acid as the capping agent. It was found that these nanocubes can simultaneously exhibited four-color (blue, green, red and NIR) upconversion emissions under a single 980?nm near-infrared (NIR) laser excitation, which should have potential multicolor in vivo imaging applications. Specifically, the red (660?nm) and NIR (800?nm) peaks, known as two "optical windows" for imaging biological tissues, were strong. The spectral and pump analyses indicated the two-photon processes were responsible for the both red and NIR emissions. PMID:26608870

  6. X-ray emission line spectroscopy of cataclysmic variables. II. Temperatures and densities from line ratios in the Chandra HETG band

    SciTech Connect

    Schlegel, E. M.; Shipley, H. V.; Rana, V. R.; Barrett, P. E.; Singh, K. P. E-mail: vrana@srl.caltech.edu E-mail: singh@tifr.res.in

    2014-12-10

    We summarize the results of a line-by-line fitting analysis of the available spectra obtained using the Chandra High-Energy Transmission Grating. We confirm the existence of broad ionization and electron temperature ranges and high number densities in cataclysmic variables (CVs) of all subtypes. Temperatures range from ?0.4 keV to ?5-10 keV or more with a broad range detected in any given CV. In other words, single-temperature models do not describe the line emission. Number densities also cover a broad range, from 10{sup 12} to >10{sup 16} cm{sup –3}. We demonstrate that much of the plasma is in a nonequilibrium state; the Fe emission, however, may arise from plasma in the ionization equilibrium.

  7. Triple-doped KMnF3:Yb3+/Er3+/Tm3+ nanocubes: four-color upconversion emissions with strong red and near-infrared bands

    PubMed Central

    Wang, Hao; Hong, Xiaodong; Han, Renlu; Shi, Junhui; Liu, Zongjun; Liu, Shujuan; Wang, You; Gan, Yang

    2015-01-01

    Triple-doped (Yb3+/Er3+/Tm3+) KMnF3 nanocubes with uniform sizes of 250?nm were synthesized by a facile hydrothermal route using the oleic acid as the capping agent. It was found that these nanocubes can simultaneously exhibited four-color (blue, green, red and NIR) upconversion emissions under a single 980?nm near-infrared (NIR) laser excitation, which should have potential multicolor in vivo imaging applications. Specifically, the red (660?nm) and NIR (800?nm) peaks, known as two “optical windows” for imaging biological tissues, were strong. The spectral and pump analyses indicated the two-photon processes were responsible for the both red and NIR emissions. PMID:26608870

  8. Multicolor tuning towards single red-emission band of upconversion nanoparticles for tunable optical component and optical/x-ray imaging agents via Ce3+ doping

    NASA Astrophysics Data System (ADS)

    Yi, Zhigao; Zeng, Tianmei; Xu, Yaru; Lu, Wei; Qian, Chao; Liu, Hongrong; Zeng, Songjun; Hao, Jianhua

    2015-09-01

    A simple strategy of Ce3+ doping is proposed to realize multicolor tuning and predominant red emission in BaLnF5:Yb3+/Ho3+ (Ln3+ = Gd3+, Y3+, Yb3+) systems. A tunable upconversion (UC) multicolor output from green/yellow to red can be readily achieved in a fixed Yb3+/Ho3+ composition by doping Ce3+, providing an effective route for multicolor tuning widely used for various optical components. Moreover, compared with Ce3+-free UC nanoparticles (UCNPs), a remarkable enhancement of the red-to-green (R/G) ratio is observed by doping 30% Ce3+, arising from the two largely promoted cross-relaxation (CR) processes between Ce3+ and Ho3+. UCNPs with pure red emission are selected as in vivo UC bioimaging agents, demonstrating the merits of deep penetration depth, the absence of autofluorescence and high contrast in small animal bioimaging. Moreover, such fluorescence imaging nanoprobes can also be used as contrast agents for three-dimensional (3D) x-ray bioimaging by taking advantage of the high K-edge values and x-ray absorption coefficients of Ba2+, Gd3+, and Ce3+ in our designed nanoprobes. Thus, the simultaneous realization of multicolor output, highly enhanced R/G ratio, and predominant red emission makes the Ce3+-doped UCNPs very useful for widespread applications in optical components and bioimaging.

  9. Multicolor tuning towards single red-emission band of upconversion nanoparticles for tunable optical component and optical/x-ray imaging agents via Ce(3+) doping.

    PubMed

    Yi, Zhigao; Zeng, Tianmei; Xu, Yaru; Lu, Wei; Qian, Chao; Liu, Hongrong; Zeng, Songjun; Hao, Jianhua

    2015-09-25

    A simple strategy of Ce(3+) doping is proposed to realize multicolor tuning and predominant red emission in BaLnF5:Yb(3+)/Ho(3+) (Ln(3+) = Gd(3+), Y(3+), Yb(3+)) systems. A tunable upconversion (UC) multicolor output from green/yellow to red can be readily achieved in a fixed Yb(3+)/Ho(3+) composition by doping Ce(3+), providing an effective route for multicolor tuning widely used for various optical components. Moreover, compared with Ce(3+)-free UC nanoparticles (UCNPs), a remarkable enhancement of the red-to-green (R/G) ratio is observed by doping 30% Ce(3+), arising from the two largely promoted cross-relaxation (CR) processes between Ce(3+) and Ho(3+). UCNPs with pure red emission are selected as in vivo UC bioimaging agents, demonstrating the merits of deep penetration depth, the absence of autofluorescence and high contrast in small animal bioimaging. Moreover, such fluorescence imaging nanoprobes can also be used as contrast agents for three-dimensional (3D) x-ray bioimaging by taking advantage of the high K-edge values and x-ray absorption coefficients of Ba(2+), Gd(3+), and Ce(3+) in our designed nanoprobes. Thus, the simultaneous realization of multicolor output, highly enhanced R/G ratio, and predominant red emission makes the Ce(3+)-doped UCNPs very useful for widespread applications in optical components and bioimaging. PMID:26335515

  10. New Kronig-Penney Equation Emphasizing the Band Edge Conditions

    ERIC Educational Resources Information Center

    Szmulowicz, Frank

    2008-01-01

    The Kronig-Penney problem is a textbook example for discussing band dispersions and band gap formation in periodic layered media. For example, in photonic crystals, the behaviour of bands next to the band edges is important for further discussions of such effects as inhibited light emission, slow light and negative index of refraction. However,…

  11. 31. TACOMA NARROWS BRIDGE, LOOKING WEST ACROSS TOLL PLAZA, 29 ...

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

    31. TACOMA NARROWS BRIDGE, LOOKING WEST ACROSS TOLL PLAZA, 29 AUGUST 1940. (ELDRIDGE, CLARK M. TACOMA NARROWS BRIDGE, TACOMA, WASHINGTON, FINAL REPORT ON DESIGN AND CONSTRUCTION, 1941) - Tacoma Narrows Bridge, Spanning Narrows at State Route 16, Tacoma, Pierce County, WA

  12. 30. TACOMA NARROWS BRIDGE, LOOKING EAST THROUGH TOLL LANES, 29 ...

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

    30. TACOMA NARROWS BRIDGE, LOOKING EAST THROUGH TOLL LANES, 29 AUGUST 1940. (ELDRIDGE, CLARK H. TACOMA NARROWS BRIDGE, TACOMA, WASHINGTON, FINAL REPORT ON DESIGN AND CONSTRUCTION, 1941) - Tacoma Narrows Bridge, Spanning Narrows at State Route 16, Tacoma, Pierce County, WA

  13. Measurement of [OIII] Emission in Lyman Break Galaxies

    E-print Network

    H. I. Teplitz; M. A. Malkan; C. C. Steidel; I. S. McLean; E. E. Becklin; D. F. Figer; A. M. Gilbert; J. R. Graham; J. E. Larkin; N. A. Levenson; M. K. Wilcox

    2000-05-11

    Measurements of [OIII] emission in Lyman Break galaxies (LBGs) at z>3 are presented. Four galaxies were observed with narrow-band filters using the Near-IR Camera on the Keck I 10-m telescope. A fifth galaxy was observed spectroscopically during the commissioning of NIRSPEC, the new infrared spectrometer on Keck II. The emission-line spectrum is used to place limits on the metallicity. Comparing these new measurements with others available from the literature, we find that strong oxygen emission in LBGs may suggest sub-solar metallicity for these objects. The [OIII]5007 line is also used to estimate the star formation rate (SFR) of the LBGs. The inferred SFRs are higher than those estimated from the UV continuum, and may be evidence for dust extinction.

  14. Sporadic narrowband radio emissions from Uranus. Progress report

    SciTech Connect

    Kurth, W.S.; Gurnett, D.A.; Scarf, F.L.

    1986-05-01

    Among several different types of radio emissions discovered at Uranus during the Voyager 2 encounter in January 1986 is a very sporadic, bursty signal which consists of very narrow bands lying in the frequency range from about 3 to 10 kHz. The bursty emission was virtually undetectable from the dayside portion of the Voyager 2 trajectory but was observed out to beyond 300 RU during the outbound trajectory through the pre-dawn sector. While the narrowband tones making up this emission are reminiscent of escaping continuum radiation observed near Earth, Jupiter, and Saturn, the Uranian signals show large amplitude variations on time scales of a second suggesting a very different type of generation mechanism.

  15. An interpretation of a mysterious 3.0- to 4.6-kHz emission band observed on Voyager 2 near Neptune

    NASA Technical Reports Server (NTRS)

    Sonwalkar, Vikas S.; Inan, Umran S.; Bell, Timothy F.

    1995-01-01

    A whistler mode interpretation is provided for the narrowband signal (f approx. 3 - 4.6 kHz, Delta f approx. 200 - 800 Hz) detected by the plasma wave instrument on Voyager 2 during its encounter with Neptune. Our analysis indicates that this signal may have been generated in a limited spatial region and that it propagated to other regions of the Neptunian magnetosphere in the nonducted whistler mode with wave normal vectors lying close to the whistler mode resonance cone. The observed frequency variation of the emission along the Voyager 2 trajectory is consistent with this interpretation. The source location is estimated to be near the magnetic equator at L approx. 4 and dipole longitude of 111 deg W (260 deg W longitude in Neptune coordinate system). The source frequency and bandwidth are estimated to be 3.6 kHz and 300 Hz, respectively. The waves most likely would have been generated by energetic electrons with 2- to 20-keV parallel energy via a gyroresonance mechanism. Our interpretation of the narrowband emissions places the following limits on the Neptunian thermal plasma density and temperature: (1) N(sub e, min) greater than 0.16 el/cu cm for 1.2 R(sub N) less than R less than 5 R(sub N), (2) N(sub e, max) = 597.5/cu cm at R - 1.3 R(sub N), (3) T(sub e, max) less than 500-1000 K at R approx. 5 R(sub N). It is also possible that the weak UV aurora observed near Neptune could have been caused by the precipitation of energetic particles by the narrowband emission as a result of wave particle interactions.

  16. Red-blue-green solid state light sources using a narrow line-width green phosphor.

    PubMed

    Liu, A; Khanna, A; Dutta, P S; Shur, M

    2015-04-01

    We demonstrate that using a narrow line-width green phosphor with the peak wavelength closely aligned with the peak in the human eye sensitivity significantly improves the Luminous Efficacy of Radiation (LER) for Red-Green-Blue (RGB) emitters. Compared to the traditional RGB sources, the improvement in LER of 20 lm/W can be achieved. Combining the narrow band green phosphor with conventional wide band red and blue phosphors allows for trading off these improvements against the deviation from the Planckian locus for even higher LER. The light sources with the narrow line green phosphor are particularly promising for high energy efficiency and high intensity illumination, where somewhat compromises can be made in the color quality such as in automotive, outdoor spaces, industrial ware-houses, public places (train stations, airports) etc.. PMID:25968796

  17. Time-resolved fluorescence line-narrowing of Eu3+ in biocompatible eutectic glass-ceramics.

    PubMed

    Sola, D; Balda, R; Al-Saleh, M; Peña, J I; Fernández, J

    2013-03-11

    The spectroscopic properties of Eu(3+) in biocompatible glass and glass-ceramic eutectic rods of composition 0.8CaSiO(3)-0.2Ca(3)(PO(4))(2) doped with 0.5 wt% of Eu(2)O(3) are investigated to explore their potential applications as optical probes. The samples were obtained by the laser floating zone technique. Depending on the growth rate, they exhibit three (two crystalline and one amorphous) or two (one crystalline and one amorphous) phases. The crystalline phases correspond to Ca(2)SiO(4) and apatite-like structures. At high growth rates the system presents an amorphous arrangement which gives a glass phase. The results of time-resolved fluorescence line narrowing spectroscopy obtained under excitation within the inhomogeneous broadened (7)F(0)?(5)D(0) absorption band allow to isolate the emission from Eu(3+) ions in the crystalline and amorphous environments and to accurately correlate the spectroscopic properties with the microstructure of these eutectics. PMID:23482227

  18. H II emission line region in LEDA 212995, a small neighboring galaxy of Mrk 1040

    E-print Network

    L. C. Popovic; E. G. Mediavilla; E. Bon; D. Ilic; G. Richter

    2004-02-01

    We present here new spectroscopic observations of Mrk 1040 and LEDA 212995 (Mrk 1040 companion) obtained with the Isaac Newton Telescope (INT). The intensity ratios and widths for the narrow emission lines found in LEDA 212995 are typical of H II regions. The red-shift (0.0169$\\pm$0.00015) of the object derived from these emission lines is very close to the red-shift of Mrk 1040 (z=0.01665). The weak narrow and broad absorption lines were detected in the H$\\alpha$ wavelength band of LEDA 212995 spectra. These absorptions indicate that the companion might be at least partly obscured by Mrk 1040. Using this and previous observations we discuss the possible physical relationship between these two galaxies.

  19. Investigation and interpretation of band broadening in size exclusion chromatography.

    PubMed

    Busnel, J P; Foucault, F; Denis, L; Lee, W; Chang, T

    2001-09-28

    Study of Band Broadening occurring in Size Exclusion Chromatography (SEC) is reported using very narrow PS standards obtained and characterised by Temperature Gradient Interaction Chromatography (TGIC). Chromatograms are fitted by Exponentially Modified Gaussian functions (EMG) and mapping of band broadening is obtained for different column sets. Interpretation of the skewing of the chromatograms is proposed with a new model using Brownian motion properties inside the pores. That explains why band broadening and tailing become so important near total exclusion volume. PMID:11681580

  20. Infants Experience Perceptual Narrowing for Nonprimate Faces

    ERIC Educational Resources Information Center

    Simpson, Elizabeth A.; Varga, Krisztina; Frick, Janet E.; Fragaszy, Dorothy

    2011-01-01

    Perceptual narrowing--a phenomenon in which perception is broad from birth, but narrows as a function of experience--has previously been tested with primate faces. In the first 6 months of life, infants can discriminate among individual human and monkey faces. Though the ability to discriminate monkey faces is lost after about 9 months, infants…