Sample records for narrow emission band

  1. Efficient narrow-band light emission from a single carbon nanotube pn diode

    E-print Network

    Perebeinos, Vasili

    Efficient narrow-band light emission from a single carbon nanotube p­n diode Thomas Mueller1. Here, we report electrically induced light emission from individual carbon nanotube p­n diodes. A new building blocks of almost all of today's optoelectronic devices are p­n junction diodes, including

  2. Leaf Level Chlorophyll Fluorescence Emission Spectra: Narrow Band versus Full 650-800 nm Retrievals

    NASA Astrophysics Data System (ADS)

    Middleton, E.; Zhang, Q.; Campbell, P. K.; Huemmrich, K. F.; Corp, L.; Cheng, Y.

    2012-12-01

    Recently, chlorophyll fluorescence (ChlF) retrievals in narrow spectral regions (< 1 nm, between 750-770 nm) of the near infrared (NIR) region of Earth's reflected radiation have been achieved from satellites, including the Japanese GOSAT and the European Space Agency's Sciamachy/Envisat. However, these retrievals sample the total full-spectrum ChlF and are made at non-optimal wavelengths since they are not located at the peak fluorescence emission features. We wish to estimate the total full-spectrum ChlF based on emissions obtained at selected wavelengths. For this, we drew upon leaf emission spectra measured on corn leaves obtained from a USDA experimental cornfield in MD (USA). These emission spectra were determined for the adaxial and abaxial (i.e., top and underside) surfaces of leaves measured throughout the 2008 and 2011 growing seasons (n>400) using a laboratory instrument (Fluorolog-3, Horiba Scientific, USA), recorded in either 1 nm or 5 nm increments with monochromatic excitation wavelengths of either 532 or 420 nm. The total ChlF signal was computed as the area under the continuous spectral emission curves, summing the emission intensities (counts per second) per waveband. The individual narrow (1 or 5 nm) waveband emission intensities were linearly related to full emission values, with variable success across the spectrum. Equations were developed to estimate total ChlF from these individual wavebands. Here, we report the results for the average adaxial/abaxial emissions. Very strong relationships were achieved for the relatively high fluorescence intensities at the red chlorophyll peak, centered at 685 nm (r2= 0.98, RMSE = 5.53 x 107 photons/s) and in the nearby O2-B atmospheric absorption feature centered at 688 nm (r2 = 0.94, RMSE = 4.04 x 107), as well as in the far-red peak centered at 740 nm (r2=0.94, RMSE = 5.98 x107). Very good retrieval success occurred for the O2-A atmospheric absorption feature on the declining NIR shoulder centered at 760 nm (r2 = 0.88, RMSE = 7.54 x 107). When perfect retrievals were assumed (0% noise), retrievals remained good in the low emission regions on either side of the peaks-- those associated with the H alpha line at 655 nm (r2 = 0.83, RMSE =8.87 x 107) and the far-NIR wavelengths recently utilized for satellite retrievals: a K line at 770 nm (r2 = 0.85, RMSE = 8.36 x 107) and the 750-770 nm interval (r2 = 0.88, RMSE = 6.92 x 107). However, the atmosphere and satellite observations are expected to add noise to retrievals. Adding 5% random error to these relationships did not seriously impair the retrieval successes in the red and far-red peaks (r2 ~ 0.85, RMSEs = 6.31 x 107). A greater impact occurred (reducing retrieval success by ~10%) when adding 5% noise for the far-NIR narrow band at 770 nm (r2 ~ 0.70, RMSE ~ 8.5 x 107). When a 10% random error was added, the retrieval successes fell to ~68 ± 7% for all retrieval wavebands, and RMSEs increased by a factor of 10. This laboratory approach will be critical to calibrate space borne retrievals, but additional information across plant species is needed. Furthermore, this experiment indicates that ChlF retrievals from space should include information from the red and far-red peak emission regions, since the true total fluorescence signal is the desired parameter for Earth carbon and energy budgets.

  3. Enhanced tunable narrow-band THz emission from laser-modulated electron beams

    SciTech Connect

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

    2009-06-19

    We propose and analyze a scheme to generate enhanced narrow-band terahertz (THz) radiation through down-conversion of the frequency of optical lasers using laser-modulated electron beams. In the scheme the electron beam is first energy modulated by two lasers with wave numbers k{sub 1} and k2, respectively. After passing through a dispersion section, the energy modulation is converted to density modulation. Due to the nonlinear conversion process, the beam will have density modulation at wave number k = nk{sub 1} + mk{sub 2}, where n and m are positive or negative integers. By properly choosing the parameters for the lasers and dispersion section, one can generate density modulation at THz frequency in the beam using optical lasers. This density-modulated beam can be used to generate powerful narrow-band THz radiation. Since the THz radiation is in tight synchronization with the lasers, it should provide a high temporal resolution for the optical-pump THz-probe experiments. The central frequency of the THz radiation can be easily tuned by varying the wavelength of the two lasers and the energy chirp of the electron beam. The proposed scheme is in principle able to generate intense narrow-band THz radiation covering the whole THz range and offers a promising way towards the tunable intense narrow-band THz sources.

  4. Quantitative Method for the Optimal Subtraction of Continuum Emission from Narrow-band Images: Skewness Transition Analysis

    NASA Astrophysics Data System (ADS)

    Hong, Sungryong; Calzetti, Daniela; Dickinson, Mark

    2014-01-01

    We present an objective method to remove the stellar continuum emission from narrow--band images to derive emission--line images. The method is based on the skewness of the pixel histogram of the residual images. Specifically, we exploit a transition in the skewness of the signal in the continuum--subtracted image, which appears when the image changes from being undersubtracted to oversubtracted. Tests on one--dimensional artificial images demonstrate that the transition identifies the optimal scaling factor ? to be used on the broad-band image IB in order to produce the optimal line--emission image IE, i.e., IE = IN-?IB, with IN the original (unsubtracted) narrow--band image. The advantage of this method is that it uses all information--bearing pixels in the final image, and not just a subset of those pixels (the latter being common in many traditional approaches to stellar continuum removal from narrow--band images). We apply our method to actual images, both from ground--based and space facilities, in particular to WFPC2 and ACS images from the Hubble Space Telescope, and we show that it is successful irrespective of the nature of the sources (point-like or extended). We also discuss the impact on the accuracy of the method of nonoptimal images, such as those containing saturated sources or nonuniform background, and present workarounds for those problems.

  5. Determination of longwave anisotropic emission factors from combined broad- and narrow-band radiance measurements

    Microsoft Academic Search

    C. Stubenrauch; J.-Ph. Duvel; R. S. Kandel

    1994-01-01

    The conversion of measured broad-band radiances into radiative fluxes requires application of angular corrections: In the Earth Radiation Budget Experiment (ERBE), the longwave anisotropic emission factors (AEF) were tabulated for different viewing zenith angles, seasons, latitude bands and scence types including four different cloud cover classes. Investigating an alternative approach for the ScaRaB (Scanner for Radiation Balance) instrument, we use

  6. Efficient narrow-band light emission from a single carbon nanotube p-n diode.

    PubMed

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

    2010-01-01

    Electrically driven light emission from carbon nanotubes could be used in nanoscale lasers and single-photon sources, and has therefore been the focus of much research. However, high electric fields and currents have either been necessary for electroluminescence, or have been an undesired side effect, leading to high power requirements and low efficiencies. Furthermore, electroluminescent linewidths have been broad enough to obscure the contributions of individual optical transitions. Here, we report electrically induced light emission from individual carbon nanotube p-n diodes. A new level of control over electrical carrier injection is achieved, reducing power dissipation by a factor of up to 1,000, and resulting in zero threshold current, negligible self-heating and high carrier-to-photon conversion efficiencies. Moreover, the electroluminescent spectra are significantly narrower ( approximately 35 meV) than in previous studies, allowing the identification of emission from free and localized excitons. PMID:19915571

  7. Narrow band wave emissions and noise around the plasma frequency in the solar wind

    NASA Astrophysics Data System (ADS)

    Chugunov, Yu. V.; Hayosh, M.; Fiala, V.; Soucek, J.; Santolik, O.; Pickett, J.

    2007-08-01

    The wave data obtained with a wide band instrument were recently used for interpretation of both quasi-thermal noise spectra and narrow band signals observed in the near vicinity of the local plasma frequency on CLUSTER II spacecraft in the solar wind, well upstream of the Earth's bow shock [1, 2] This approach is planned to continue with the large Cluster database and will be of use for other space missions such as Stereo and Solar Orbiter. If available, multi-component and/or multi-point measurements are expected to provide even greater insight in the generation of radio waves in the heliosphere in this frequency range. Our approach is based on a novel study of performance of receiving antennas in resonance regions in a streaming plasma. As far as noise spectra is concerned two distinctive features appear: a cutoff shifted down below the plasma frequency by a factor proportional to the ratio of stream velocity to the electron thermal velocity squared. The spectral maximum depends on the orientation of the antenna axis with respect to the stream velocity; it is shifted above the plasma frequency according to the antenna orientation, which is changing with the spacecraft spin. When the time resolution of the instrument is sufficient, it is possible to follow these changes. The overall form of the spectrum depends on the plasma distribution function, but even with a simplified model of two electron populations with largely different temperatures the estimates of the drift velocity and/or the temperature of the hot component can be obtained. In the case of a quasi-harmonic wave (narrow band signal) incident on the antenna, it is the antenna's effective length that allows for conversion of the open circuit voltage induced on its terminals to the electric field of the incoming wave. We show that this effective length grows by more than an order of magnitude under resonance conditions. This was already confirmed for waves propagating close to the lower oblique resonance cone in a magnetized plasma of the polar ionosphere in the Oedipus-C rocket experiment [3]. The fact that the effective length can exceed the antenna physical length might seem counterintuitive. Our explanation is related to the fact that in such cases the wave number surfaces (of Langmuir waves in a streaming plasma, or waves on the resonance cone in a magnetized plasma) show directions where either two waves coalesce, with the group velocity perpendicular to the phase velocity, or there exists a whole grouping of waves with a large spectrum of wave vectors but propagating in a narrow angle downstream with the solar wind at the plasma frequency. In the spectra obtained from wide band instrument on Cluster when the spacecraft was in the solar wind, an intense narrow line appears near the plasma frequency above the background of quasi-thermal noise, sporadically but not rarely. The existence, frequency dependence, bandwidth and amplitude of the background noise are quite well explained with a model of a two temperature plasma mentioned above. The amplitude of the narrow line exceeds the noise by about an order of magnitude. According to our findings the waves going downstream from the source to the receiver are recorded with high amplitude, so that the overall appearance of the waveforms conforms well with a signature of a source of plasma waves situated upstream from the spacecraft modulated due to the interplay of radiation patterns of the source and the receiving antenna. As these wave trains are often recorded by at least two spacecraft with a small time shift, a location and even the spatial extent of the source can be estimated. The amplitude modulation of such a signal contains also information on the radiation source, which may be e.g. a particle beam radiating through the Cherenkov effect. In such a case the radiation pattern is that of an electric field distribution on a Cherenkov cone emanating from the source and crossing the receiving point on either spacecraft. We conclude that this approach is able to help in understanding of spectral amplitudes

  8. Determination of longwave anisotropic emission factors from combined broad- and narrow-band radiance measurements

    NASA Astrophysics Data System (ADS)

    Stubenrauch, C.; Duvel, J.-Ph.; Kandel, R. S.

    1994-01-01

    The conversion of measured broad-band radiances into radiative fluxes requires application of angular corrections: In the Earth Radiation Budget Experiment (ERBE), the longwave anisotropic emission factors (AEF) were tabulated for different viewing zenith angles, seasons, latitude bands and scence types including four different cloud cover classes. Investigating an alternative approach for the ScaRaB (Scanner for Radiation Balance) instrument, we use a radiative transfer model to parametrize the AEF as a function of viewing zenith angle and a single other variable - `atmospheric pseudo-absorptance' - extracted from simultaneously measured broad-band longwave (LW) and infrared (IR) atmospheric window (10.5-12.5?m) radiances. For validation, we use simultaneous co-located NOAA-9 AVHRR-ERBE data. Compared to the ERBE AEF's the ScaRaB parametrization provides more realistic AEF's as a function of scene brightness temperature which is related to cloud top height. Analysis of classified cloud data indicates that there are only a few extreme cases in which additional anisotropy due to broken clouds will affect the usefulness of our parametrization. We also consider enhanced anisotropy of semitransparent cirrus. Model and data show that although not explicitly treated in our procedure, the parametrization gives good results.

  9. 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 ...

  10. 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. [University of California, Berkeley, 110 Sproul Hall, Berkeley, CA 94720 (United States)] [University of California, Berkeley, 110 Sproul Hall, Berkeley, CA 94720 (United States); Demorest, Paul; Maddalena, Ron J.; Langston, Glen [National Radio Astronomy Observatory, 520 Edgemont Rd Charlottesville, VA 22903 (United States)] [National Radio Astronomy Observatory, 520 Edgemont Rd Charlottesville, VA 22903 (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii, 640 North A'ohoku Place, 209 Hilo, HI 96720-2700 (United States)] [Institute for Astronomy, University of Hawaii, 640 North A'ohoku Place, 209 Hilo, HI 96720-2700 (United States); Tarter, Jill [SETI Institute, 189 Bernardo Ave 100 Mountain View, CA 94043 (United States)] [SETI Institute, 189 Bernardo Ave 100 Mountain View, CA 94043 (United States)

    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.

  11. 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.

  12. Sensitive IR narrow band optimized microspectrometer

    Microsoft Academic Search

    David L Wetzel

    2002-01-01

    Customization of a standard model confocally masked FT-IR microspectrometer to maximize the signal for a particular narrow band of the spectrum and minimize noise is described. In this case the motivation was to detect minor concentrations of deuterated species in a matrix of tissue. However, the instrumental modifications used for this particular task are applicable to narrow band sensitization in

  13. Electron correlation in narrow band systems

    NASA Astrophysics Data System (ADS)

    Kishore, R.

    1983-03-01

    The effect of the electron correlations in narrow bands, such as d(f) bands in the transition (rare earth) metals and their compounds and the impurity bands in doped semiconductors, are studied. The narrow band systems are described by the Hubbard Hamiltonian. By proposing a local self-energy for the interacting electrons, we found that our results are exact in both atomic and band limits and reduce to the Hartree Fock results for U/delta yield 0, where U is the intra-atomic Coulomb interaction and delta is the bandwidth of the noninteracting electrons. For the Lorentzian form of the density of states of the noninteracting electrons, our approximation turns out to be equivalent to the third Hubbard approximation. A simple argument, based on the mean free path obtained from the imaginary part of the self energy, shows how the electron correlations can give rise to a discontinuous metal-nonmetal transition as proposed by Mott. The band narrowing and the existence of the satellite below the Fermi energy in Ni, found in photoemission experiments, can also be understood.

  14. 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…

  15. Adaptive suppression of narrow-band vibrations

    Microsoft Academic Search

    E. Bertran; G. Montoro

    1998-01-01

    The aim of the paper is to develop a theoretical analysis and implementation of an active control canceller devoted to eliminate narrow-band vibrations in rotary machines. The proposed system uses a bank of digital adaptive notch filters each of them adjusted by an LMS algorithm. The theoretical results are applied to a vibrating DC motor considered as a benchmark problem.

  16. 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

  17. Narrow-band nonlinear sea waves

    NASA Technical Reports Server (NTRS)

    Tayfun, M. A.

    1980-01-01

    Probabilistic description of nonlinear waves with a narrow-band spectrum is simplified to a form in which each realization of the surface displacement becomes an amplitude-modulated Stokes wave with a mean frequency and random phase. Under appropriate conditions this simplification provides a convenient yet rigorous means of describing nonlinear effects on sea surface properties in a semiclosed or closed form. In particular, it is shown that surface displacements are non-Gaussian and skewed, as was previously predicted by the Gram-Charlier approximation; that wave heights are Rayleigh distributed, just as in the linear case; and that crests are non-Rayleigh.

  18. f-band narrowing in uranium intermetallics

    SciTech Connect

    Dunlap, B.D.; Litterst, F.J.; Malik, S.K.; Kierstead, H.A.; Crabtree, G.W.; Kwok, W.; Lam, D.J.; Mitchell, A.W.

    1987-01-01

    Although the discovery of heavy fermion behavior in uranium compounds has attracted a great deal of attention, relatively little work has been done which is sufficiently systematic to allow an assessment of the relationship of such behavior to more common phenomena, such as mixed valence, narrow-band effects, etc. In this paper we report bulk property measurements for a number of alloys which form a part of such a systematic study. The approach has been to take relatively simple and well-understood materials and alter their behavior by alloying to produce heavy fermion or Kondo behavior in a controlled way.

  19. THZ EMISSION SPECTROSCOPY OF NARROW BANDGAP SEMICONDUCTORS

    E-print Network

    Wilke, Ingrid

    THZ EMISSION SPECTROSCOPY OF NARROW BANDGAP SEMICONDUCTORS By Ricardo Asc´azubi A Thesis Submitted-Domain Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 Optically Excited THz Emission Processes Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.1 THz-TDS Setup

  20. Narrow band 3 × 3 Mueller polarimetric endoscopy.

    PubMed

    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

  1. 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

  2. Jovian narrow-band as generator of the Jovian millisecond radio bursts

    NASA Astrophysics Data System (ADS)

    Boudjada, M. Y.; Galopeau, P. H. M.; Rucker, H. O.; Lecacheux, A.

    2000-11-01

    We report on the narrow-band emissions observed in the dynamic spectra of the Jovian decametric radio emissions. Such narrow-band emissions are infrequent phenomena and are related to the Jovian millisecond radio bursts (S-bursts). From the Riihimaa catalogue (Riihimaa 1991) we select narrow-band events observed in Oulu (Finland) with an acousto-optic spectrograph (AOS) with a high time resolution of about 7 ms. The AOS receiver gives the possibility to study the relationship between the S-bursts and the Jovian narrow-band emissions. For this we use the Riihimaa classification which shows sketches of millisecond radio bursts as they appear on the dynamic spectra and allows to distinguish one S-burst from another. The analysis of the temporal evolution of the Jovian narrow-band leads to a new interpretation of the Riihimaa structures. We show that each individual structure could be decomposed in one, two or three components and related to the narrow-band. It appears that the temporal evolution of the narrow-band involves the presence of fine structures, i.e. S-bursts, with a short time duration of about few tens of milliseconds. The individual S-burst duration and the short time scale of the gap in the narrow-band account for a mechanism totally intrinsic to the radio source. Taking into consideration our new results, we show that two models, the feedback model (Calvert 1982) and filamentary model (Louarn 1997) could explain part but not the global observed features of the narrow-band. According to the previous models the drift rate of the individual S-bursts seems to associate the combined effect of the source width with the refractive index or the geometry of the source relatively to the observer.

  3. Narrow band images of suspected cooling flow galaxies

    NASA Technical Reports Server (NTRS)

    Deustua, Susana; Bothun, Greg

    1990-01-01

    Narrow-band (H alpha and (NII)) charge coupled device (CCD) images of elliptical galaxies suspected of having cooling flows are discussed. Researchers find evidence of optical emission from cool gas which is most likely associated with a cooling flow. At least 4 galaxies (NGC 3998, NGC 4203, NGC 4550 and NGC 4697) show emission of (NII) and/or H alpha within the central 20 seconds, a fraction consistent with results from Phillips et al. (1987) and Caldwell (1984). In these four, (NII) lambda 6584A emission is stronger than H alpha (which is often in absorption e.g., as seen in long slit spectra of NGC4697). From long slit spectra of these galaxies, Deustua and Teske (1989) infer electron densities, N sub e, of order 1.2x10 to the 3rd power cm(-3) assuming T = 10 to the 4th power K for the optically emitting gas. NGC 2685, NGC 3489 appear to have emission in (NII); NGC 4636 may also, but, is difficult to see in the data (Demoulin-Ulrich, Butcher and Boksenberg (1984) did not see emission from this galaxy). NGC 4472, NGC 4473, NGC 4365, NGC 4638 and NGC 4649 show no emission.

  4. Narrow frequency-band laser with optical feedback

    E-print Network

    Childress, Michael J

    2005-01-01

    In this paper we discuss the construction of a narrow frequency-band laser with optical feedback. We use a distributed Bragg reflector (DBR) laser diode centered at the cesium D? transition wavelength, [gamma] = 852 nm. ...

  5. Robust Pitch Detection by Narrow Band Spectrum Analysis 

    E-print Network

    Shimodaira, Hiroshi; Nakai, Mitsuru

    This paper proposes a new technique for detecting pitch patterns which is useful for automatic speech recognition, by using a narrow band spectrum analysis. The motivation of this approach is that humans perceive some kind ...

  6. Narrow-band surveys for very high redshift Lyman-? emitters

    NASA Astrophysics Data System (ADS)

    Nilsson, K. K.; Orsi, A.; Lacey, C. G.; Baugh, C. M.; Thommes, E.

    2007-11-01

    Context: Many current and future surveys aim to detect the highest redshift (z ? 7) sources through their Lyman-? (Ly?) 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? emitters at z ? 7 based on a variety of approaches calibrated and tested on observational data at lower redshifts. 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? emitters. We also investigate what constraints future observations will be able to place on the Ly? luminosity function at very high redshift. Conclusions: It should be possible to observe z = 7{-}10 Ly? 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? luminosity function, instruments further in the future, such as an ELT, will be necessary.

  7. Tunable narrow band source via the strong coupling between optical emitter and nanowire surface plasmons

    E-print Network

    J. Yang; G. W. Lin; Y. P. Niu; Y. H. Qi; F. X. Zhou; S. Q. Gong

    2014-12-30

    The spectrum width can be narrowed to a certain degree by decreasing the coupling strength for the two-level emitter coupled to the propagating surface plasmon. But the width can not be narrowed any further because of the loss of the photon out of system by spontaneous emission from the emitter. Here we propose a new scheme to construct a narrow-band source via a one-dimensional waveguide coupling with a three-level emitter. It is shown that the reflective spectrum width can be narrowed avoiding the impact of the loss. This approach opens up the possibility of plasmonic ultranarrow single-photon source.

  8. Narrow-band analysis of nonstationary processes

    NASA Astrophysics Data System (ADS)

    Robinson, P. M.; Marinucci, Domenico

    The behavior of averaged periodograms and cross-periodograms of a broad class of nonstationary processes is studied. The processes include nonstationary ones that are fractional of any order, as well as asymptotically stationary fractional ones. The cross-periodogram can involve two nonstationary processes of possibly different orders, or a nonstationary and an asymptotically stationary one. The averaging takes place either over the whole frequency band, or over one that degenerates slowly to zero frequency as sample size increases. In some cases it is found to make no asymptotic difference, and in particular we indicate how the behavior of the mean and variance changes across the two-dimensional space of integration orders. The results employ only local-to-zero assumptions on the spectra of the underlying weakly stationary sequences. It is shown how the results can be applied in fractional cointegration with unknown integration orders.

  9. Combination phototherapy of psoriasis with narrow-band UVB irradiation and topical tazarotene gel

    Microsoft Academic Search

    Stefanie Behrens; Marcella Grundmann-Kollmann; Ralf Schiener; Ralf-Uwe Peter; Martina Kerscher

    2000-01-01

    Background: Narrow-band UVB (311 nm) phototherapy offering an emission spectrum closely conforming to the peak of the action spectrum for clearing psoriasis has significantly improved phototherapy for psoriasis. Because the majority of the commonly used topical therapies in treatment of psoriasis have limitations, a need for new topical agents remains. Tazarotene has been shown to be efficacious in plaque-type psoriasis.

  10. Narrow-band Imagery of the ISM using the RCT

    NASA Astrophysics Data System (ADS)

    Walter, D. K.; Gelderman, R.; Guinan, E.; Howell, S.; Mattox, J. R.; McGruder, C. H., III; Davis, D.; Everett, M.

    2003-05-01

    We present the first results of imaging the Interstellar Medium (ISM) using narrow-band filters with the Robotically Controlled Telescope (RCT). The RCT is the recently refurbished 1.3-meter telescope at the Kitt Peak National Observatory. Details regarding the RCT can be found elsewhere at this meeting (Gelderman, R. et al.). Our filters are centered on diagnostic, nebular emission lines of the ions H+, He+, S+, N+ and O++. Objects of interest in the galactic and extragalactic ISM were observed including the starburst galaxy NGC 4449. Ionization ratio maps include [OIII]/H?, [NII]/H? and the C(H?) extinction map from the ratio of H?/H?. Electron densities are derived from the ratio of images taken through filters centered on the sulfur lines at 671.7 and 673.1 nm. Refurbishment of the RCT has been made possible by NASA NAG 58-762. Funding for filters and additional equipment has been made possible by NASA OSS NAG 5-10145 and NASA MU-SPIN NCC 5-534.

  11. A narrow band pattern-matching model of vowel perception

    NASA Astrophysics Data System (ADS)

    Hillenbrand, James M.; Houde, Robert A.

    2003-02-01

    The purpose of this paper is to propose and evaluate a new model of vowel perception which assumes that vowel identity is recognized by a template-matching process involving the comparison of narrow band input spectra with a set of smoothed spectral-shape templates that are learned through ordinary exposure to speech. In the present simulation of this process, the input spectra are computed over a sufficiently long window to resolve individual harmonics of voiced speech. Prior to template creation and pattern matching, the narrow band spectra are amplitude equalized by a spectrum-level normalization process, and the information-bearing spectral peaks are enhanced by a ``flooring'' procedure that zeroes out spectral values below a threshold function consisting of a center-weighted running average of spectral amplitudes. Templates for each vowel category are created simply by averaging the narrow band spectra of like vowels spoken by a panel of talkers. In the present implementation, separate templates are used for men, women, and children. The pattern matching is implemented with a simple city-block distance measure given by the sum of the channel-by-channel differences between the narrow band input spectrum (level-equalized and floored) and each vowel template. Spectral movement is taken into account by computing the distance measure at several points throughout the course of the vowel. The input spectrum is assigned to the vowel template that results in the smallest difference accumulated over the sequence of spectral slices. The model was evaluated using a large database consisting of 12 vowels in /hVd/ context spoken by 45 men, 48 women, and 46 children. The narrow band model classified vowels in this database with a degree of accuracy (91.4%) approaching that of human listeners.

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

    E-print Network

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

    2014-07-22

    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 output 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.

  13. 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, E-mail: christoph.becher@physik.uni-saarland.de [Universität des Saarlandes, Fachrichtung 7.2 (Experimentalphysik), Campus E2.6, 66123 Saarbrücken (Germany); Pauly, Christoph; Mücklich, Frank [Universität des Saarlandes, Fachrichtung 8.4 (Materialwissenschaft und Werkstofftechnik), Campus D3.3, 66123 Saarbrücken (Germany); Schell, Andreas W.; Engel, Philip; Benson, Oliver [Humboldt-Universität zu Berlin, Institut für Physik, AG Nanooptik, Newtonstraße 15, 12489 Berlin (Germany); Schröder, Tim [Department of Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts 02139 (United States); Humboldt-Universität zu Berlin, Institut für Physik, AG Nanooptik, Newtonstraße 15, 12489 Berlin (Germany); Reichel, Jakob [Laboratoire Kastler Brossel, ENS/UPMC-Paris 6/CNRS, 24 rue Lhomond, 75005 Paris (France)

    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.

  14. K Emission Band of Graphite

    Microsoft Academic Search

    Takasi Sagawa

    1966-01-01

    The K emission band of graphite was observed using a grazing incidence spectrometer, and unfolded with the use of Gaussian window function. The unfolding procedure reveals the intrinsic profile of the state density. The profile consists of four sub-bands. The highest one is pi-band and the lower three are sigma-bands. The overlapping between them is very small. The height of

  15. 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.

  16. Limits on neutrino oscillations in the Fermilab narrow band beam

    SciTech Connect

    Brucker, E.B.; Jacques, P.F.; Kalelkar, M.; Koller, E.L.; Plano, R.J.; Stamer, P.E.; Baker, N.J.; Connolly, P.L.; Kahn, S.A.; Murtagh, M.J.

    1986-01-01

    A search for neutrino oscillations was made using the Fermilab narrow-band neutrino beam and the 15 ft. bubble chamber. No positive signal for neutrino oscillations was observed. Limits were obtained for mixing angles and neutrino mass differences for nu/sub ..mu../ ..-->.. nu/sub e/, nu/sub ..mu../ ..-->.. nu/sub tau/, nu/sub e/ ..-->.. nu/sub e/. 5 refs.

  17. An adaptive narrow band frequency modulation voice communication system

    NASA Technical Reports Server (NTRS)

    Wishna, S.

    1972-01-01

    A narrow band frequency modulation communication system is described which provides for the reception of good quality voice at low carrier-to-noise ratios. The high level of performance is obtained by designing a limiter and phase lock loop combination as a demodulator, so that the bandwidth of the phase lock loop decreases as the carrier level decreases. The system was built for the position location and aircraft communication equipment experiment of the ATS 6 program.

  18. LOW COMPLEXITY NARROW-BAND INTERFERENCE SUPPRESSION IN IMPULSE Itsik Bergel

    E-print Network

    Bergel, Itsik

    LOW COMPLEXITY NARROW-BAND INTERFERENCE SUPPRESSION IN IMPULSE RADIO Itsik Bergel , Eran Fishler) radio systems ,enables them co-exist with other narrow-bandsystems over the same frequencyband without interfering the narrow-bandsystems. Nevertheless, the interference caused by these narrow-band systems may jam

  19. Photometric Type Ia supernova surveys in narrow-band filters

    NASA Astrophysics Data System (ADS)

    Xavier, Henrique S.; Abramo, L. Raul; Sako, Masao; Benítez, Narciso; Calvão, Maurício O.; Ederoclite, Alessandro; Marín-Franch, Antonio; Molino, Alberto; Reis, Ribamar R. R.; Siffert, Beatriz B.; Sodré, Laerte.

    2014-11-01

    We study the characteristics of a narrow-band Type Ia supernova (SN) survey through simulations based on the upcoming Javalambre Physics of the accelerating Universe Astrophysical Survey. This unique survey has the capabilities of obtaining distances, redshifts and the SN type from a single experiment thereby circumventing the challenges faced by the resource-intensive spectroscopic follow-up observations. We analyse the flux measurements signal-to-noise ratio and bias, the SN typing performance, the ability to recover light-curve parameters given by the SALT2 model, the photometric redshift precision from Type Ia SN light curves and the effects of systematic errors on the data. We show that such a survey is not only feasible but may yield large Type Ia SN samples (up to 250 SNe at z < 0.5 per month of search) with low core-collapse contamination (˜1.5 per cent), good precision on the SALT2 parameters (average ? _{m_B}=0.063, ? _{x_1}=0.47 and ?c = 0.040) and on the distance modulus (average ?? = 0.16, assuming an intrinsic scatter ?int = 0.14), with identified systematic uncertainties ?sys ? 0.10?stat. Moreover, the filters are narrow enough to detect most spectral features and obtain excellent photometric redshift precision of ?z = 0.005, apart from ˜2 per cent of outliers. We also present a few strategies for optimizing the survey's outcome. Together with the detailed host galaxy information, narrow-band surveys can be very valuable for the study of SN rates, spectral feature relations, intrinsic colour variations and correlations between SN and host galaxy properties, all of which are important information for SN cosmological applications.

  20. Narrow-band Imagery with the 1.3-meter Robotically Controlled Telescope (RCT)

    NASA Astrophysics Data System (ADS)

    Walter, Donald K.; Gelderman, Richard; Campbell, R.; Carini, Michael T.; Davis, Donald R.; Engle, Scott G.; Guinan, Edward F.; McGruder, Charles H., III; Strolger, Louis-Gregory; Tedesco, Edward F.

    2011-03-01

    The Robotically Controlled Telescope (RCT) has two filter wheels in the optical path, providing a choice of up to 16 filters (plus a clear position) for any given observation. Each circular, 113 mm (~4.5 inches) diameter filter is custom made for the RCT. The standard observing configuration is to have one filter wheel in place at all times, loaded with medium-band and standard UBVRI broad-band filters. The second slot gets filled with one of two wheels containing interference filters. One of these filter wheels contains narrow-band filters centered on diagnostic, nebular emission lines of ionized hydrogen, doubly ionized helium, [S II], [N II], [O III], and adjacent regions of the spectrum for continuum subtraction. The other wheel includes a second set of narrow-band filters centered on molecular emission lines important to the study of comets; such as OH, CN, C2, C3, and adjacent regions of the spectrum for continuum subtraction. We discuss how the number and variety of readily available filters provides powerful flexibility for the research programs undertaken by users of the 1.3-m Robotically Controlled Telescope.

  1. Role of Narrow Band Imaging in Management of Urothelial Carcinoma.

    PubMed

    Altobelli, Emanuela; Zlatev, Dimitar V; Liao, Joseph C

    2015-08-01

    Urothelial carcinoma of the bladder and upper tract is primarily diagnosed by white light endoscopy, which has well-known limitations that contribute to the increased risk of tumor recurrence and progression. Narrow band imaging (NBI) is an optical imaging technology that facilitates detection of tumor vasculature and differentiation of benign urothelium from neoplastic tissue. For urothelial carcinoma, NBI may be utilized in a variety of clinical settings, including office cystoscopy for initial identification and surveillance, transurethral resection for pathological diagnosis, and ureteroscopic management of upper tract lesions. Early evidence suggests that NBI increases the detection of urothelial carcinoma in the bladder and upper tract, including flat high-grade lesions such as carcinoma-in-situ that are a diagnostic challenge under white light. NBI also appears to improve the quality of transurethral resection and thereby reduce the frequency of tumor recurrence. PMID:26093973

  2. 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

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

    SciTech Connect

    Nong, Hanond, E-mail: Nong.Hanond@rub.de; Markmann, Sergej; Hekmat, Negar; Jukam, Nathan, E-mail: Nathan.Jukam@rub.de [Arbeitsgruppe Terahertz Spektroskopie und Technologie, Ruhr-Universität Bochum, Bochum 44780 (Germany); Pal, Shovon [Arbeitsgruppe Terahertz Spektroskopie und Technologie, Ruhr-Universität Bochum, Bochum 44780 (Germany); Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum 44780 (Germany); Mohandas, Reshma A.; Dean, Paul; Li, Lianhe; Linfield, Edmund H.; Giles Davies, A. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Wieck, Andreas D. [Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum 44780 (Germany)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  5. Measuring large-scale structure with quasars in narrow-band filter surveys

    NASA Astrophysics Data System (ADS)

    Abramo, L. Raul; Strauss, Michael A.; Lima, Marcos; Hernández-Monteagudo, Carlos; Lazkoz, Ruth; Moles, Mariano; de Oliveira, Claudia Mendes; Sendra, Irene; Sodré, Laerte; Storchi-Bergmann, Thaisa

    2012-07-01

    We show that a large-area imaging survey using narrow-band filters could detect quasars in sufficiently high number densities, and with more than sufficient accuracy in their photometric redshifts, to turn them into suitable tracers of large-scale structure. If a narrow-band optical survey can detect objects as faint as i= 23, it could reach volumetric number densities as high as 10-4 h3 Mpc-3 (comoving) at z˜ 1.5. Such a catalogue would lead to precision measurements of the power spectrum up to z˜ 3-4. We also show that it is possible to employ quasars to measure baryon acoustic oscillations at high redshifts, where the uncertainties from redshift distortions and non-linearities are much smaller than at z? 1. As a concrete example we study the future impact of the Javalambre Physics of the Accelerating Universe Astrophysical Survey (J-PAS), which is a narrow-band imaging survey in the optical over 1/5 of the unobscured sky with 42 filters of ˜100-Å full width at half-maximum. We show that J-PAS will be able to take advantage of the broad emission lines of quasars to deliver excellent photometric redshifts, ?z? 0.002 (1 +z), for millions of objects.

  6. Realization of an Active Narrow Band Filter with Electronically Controlled Defects in a Microwave Bandgap Structure

    Microsoft Academic Search

    Michael J. Hill; Richard W. Ziolkowski; John Papapolymerou

    2000-01-01

    Microwave band gap structures (MBG) utilizing fixed defects have received much interest because of their ability to operate as narrow band filters. With the recent interest in reconfigurable wireless devices, the need for electronically controllable narrow band filters is on the rise. By altering the defects in a MBG crystal, the transmission properties of the crystal can be changed. Using

  7. 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

  8. Narrow-band ultraviolet B is a useful and well-tolerated treatment for vitiligo

    Microsoft Academic Search

    Lubomira Scherschun; Jane J. Kim; Henry W. Lim

    2001-01-01

    Background: The treatment of vitiligo remains a challenge. Objective: The purpose of this article is to review our results and experience with narrow-band ultraviolet (UV) B phototherapy for vitiligo. Methods: This is a retrospective analysis of our experience and results with patients with vitiligo who were treated with narrow-band UVB between November 1998 and November 1999. Narrow-band UVB phototherapy was

  9. Endoscopic findings under narrow band imaging colonoscopy in ulcerative colitis.

    PubMed

    Esaki, Motohiro; Kubokura, Naoya; Kudo, Tetsuji; Matsumoto, Takayuki

    2011-05-01

    Narrow band imaging (NBI) depicts distinct intramucosal vascular network and pit pattern without any use of dye technique. It is thus suggested that NBI can be used for the assessment of severity in inflammatory bowel diseases, especially in ulcerative colitis (UC). In the active UC, NBI colonoscopy depicts friability as a black area. In the inflamed granular mucosa, crypt openings and villous structure become evident through the procedure. In the inactive UC, there are two types of mucosal vascular pattern; one being composed of deep, green vessels and superficial, black vessels, and the other lacking in superficial vessels. With used of a magnifying instrument, the mildly active mucosa can be classified into the mucosa with obvious crypt openings and that with villous structure. Mucosal vascular pattern in the inactive mucosa is shown as a honeycomb-like structure or irregular, tortuous structure under magnifying NBI observation. Furthermore, such NBI findings show close correlations with histologic findings including crypt distortion, goblet cell depletion and basal plasmacytosis. Therefore, NBI colonoscopy might be of value for the precise assessment of histologic severity in mildly active and inactive UC. PMID:21535220

  10. 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.

  11. Spatial analysis of solar type III events associated with narrow band spikes at metric wavelengths

    E-print Network

    G. Paesold; A. O. Benz; K. -L. Klein; N. Vilmer

    2001-03-29

    The spatial association of narrow band metric radio spikes with type III bursts is analyzed. The analysis addresses the question of a possible causal relation between the spike emission and the acceleration of the energetic electrons causing the type III burst. The spikes are identified by the Phoenix-2 spectrometer (ETH Zurich) from survey solar observations in the frequency range from 220 MHz to 530 MHz. Simultaneous spatial information was provided by the Nancay Radioheliograph (NRH) at several frequencies. Five events were selected showing spikes at one or two and type III bursts at two or more Nancay frequencies. The 3-dimensional geometry of the single events has been reconstructed by applying different coronal density models. As a working hypothesis it is assumed that emission at the plasma frequency or its harmonic is the responsible radiation process for the spikes as well as for the type III bursts. It has been found that the spike source location is consistent with the backward extrapolation of the trajectory of the type III bursts, tracing a magnetic field line. In one of the analyzed events, type III bursts with two different trajectories originating from the same spike source could be identified. These findings support the hypothesis that narrow band metric spikes are closely related to the acceleration region.

  12. Narrow-band imaging system with magnifying endoscopy for superficial esophageal lesions

    Microsoft Academic Search

    Tatsuya Yoshida; Haruhiro Inoue; Shinsuke Usui; Hitoshi Satodate; Norio Fukami; Shin-ei Kudo

    2004-01-01

    BackgroundBy assessing the intrapapillary capillary loop in esophageal mucosa, magnifying endoscopy can play an important role in the evaluation of superficial esophageal lesions. A newly developed narrow-band imaging system was applied to magnifying endoscopy in a clinical setting; the benefit of the narrow-band imaging system was evaluated.

  13. Volume 35, number 3 OPTICSCOMMUNICATIONS December 1980 NARROW-BAND UV RADIATION (250-260 nm)

    E-print Network

    Zare, Richard N.

    Volume 35, number 3 OPTICSCOMMUNICATIONS December 1980 NARROW-BAND UV RADIATION (250-260 nm) FROM-wave, tunable UV radiation (250 -260 nm) by intracavity doubling a coumarin-515 ringdye laser is descried-Doppler resolution of the Hg 6s6p 3p? - 6s2 1S0 transition. 1. Introduction Narrow-band tunable UV radiation

  14. 47 CFR 80.461 - Narrow-band direct-printing.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Narrow-band direct-printing. 80.461 Section 80.461 Telecommunication FEDERAL...Stations Use of Telegraphy § 80.461 Narrow-band direct-printing. Subpart H of this part lists the frequencies...

  15. 47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Narrow-band direct-printing (NB-DP). 80.1159 Section 80... § 80.1159 Narrow-band direct-printing (NB-DP). NB-DP is a form of...the transmission and receipt of direct printing public correspondence. Ships must...

  16. 47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Narrow-band direct-printing (NB-DP). 80.1159 Section 80... § 80.1159 Narrow-band direct-printing (NB-DP). NB-DP is a form of...the transmission and receipt of direct printing public correspondence. Ships must...

  17. 47 CFR 80.461 - Narrow-band direct-printing.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Narrow-band direct-printing. 80.461 Section 80.461 Telecommunication FEDERAL...Stations Use of Telegraphy § 80.461 Narrow-band direct-printing. Subpart H of this part lists the frequencies...

  18. 47 CFR 80.461 - Narrow-band direct-printing.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Narrow-band direct-printing. 80.461 Section 80.461 Telecommunication FEDERAL...Stations Use of Telegraphy § 80.461 Narrow-band direct-printing. Subpart H of this part lists the frequencies...

  19. 47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Narrow-band direct-printing (NB-DP). 80.1159 Section 80... § 80.1159 Narrow-band direct-printing (NB-DP). NB-DP is a form of...the transmission and receipt of direct printing public correspondence. Ships must...

  20. 47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Narrow-band direct-printing (NB-DP). 80.1159 Section 80... § 80.1159 Narrow-band direct-printing (NB-DP). NB-DP is a form of...the transmission and receipt of direct printing public correspondence. Ships must...

  1. 47 CFR 80.1159 - Narrow-band direct-printing (NB-DP).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Narrow-band direct-printing (NB-DP). 80.1159 Section 80... § 80.1159 Narrow-band direct-printing (NB-DP). NB-DP is a form of...the transmission and receipt of direct printing public correspondence. Ships must...

  2. 47 CFR 80.461 - Narrow-band direct-printing.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Narrow-band direct-printing. 80.461 Section 80.461 Telecommunication FEDERAL...Stations Use of Telegraphy § 80.461 Narrow-band direct-printing. Subpart H of this part lists the frequencies...

  3. 47 CFR 80.461 - Narrow-band direct-printing.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Narrow-band direct-printing. 80.461 Section 80.461 Telecommunication FEDERAL...Stations Use of Telegraphy § 80.461 Narrow-band direct-printing. Subpart H of this part lists the frequencies...

  4. Narrow and broad band diode laser absorption spectrometry—concepts, limitations and applications

    Microsoft Academic Search

    J. Koch; A. Zybin; K. Niemax

    2002-01-01

    Implementation concepts as well as the fundamental aspects concerning the analytical capability of diode laser spectrometry with respect to narrow and broad band absorption are discussed. The applicability is illustrated by means of the element-selective analysis of flames or plasmas and the molecular analysis of liquids or turbid media. While in narrow band absorption one diode laser and different modulation

  5. Narrow band tuning with small long pulse excimer lasers

    SciTech Connect

    Sze, R.C.; Kurnit, N.; Watkins, D.; Bigio, I.

    1985-12-01

    We discuss frequency narrowing and tuning with simple dispersion elements with small long-pulse excimer lasers. The improved performance over short-pulse lasers is discussed and attributed to the increased number of round trips. A physical model of the dynamics of line narrowing is presented.

  6. Electronically-tunable narrow-band noise source

    Microsoft Academic Search

    M. Wright

    1969-01-01

    A new narrow-bandwidth noise generator that can be electronically tuned over a wide frequency range has been developed. The device is based on the frequency-selective power-limiting characteristic of YIG materials.

  7. Searching for Narrow Emission Lines in X-ray Spectra: Computation and Methods

    E-print Network

    Taeyoung Park; David A. van Dyk; Aneta Siemiginowska

    2008-08-23

    The detection and quantification of narrow emission lines in X-ray spectra is a challenging statistical task. The Poisson nature of the photon counts leads to local random fluctuations in the observed spectrum that often results in excess emission in a narrow band of energy resembling a weak narrow line. From a formal statistical perspective, this leads to a (sometimes highly) multimodal likelihood. Many standard statistical procedures are based on (asymptotic) Gaussian approximations to the likelihood and simply cannot be used in such settings. Bayesian methods offer a more direct paradigm for accounting for such complicated likelihood functions but even here multimodal likelihoods pose significant computational challenges. The new Markov chain Monte Carlo (MCMC) methods developed in 2008 by van Dyk and Park, however, are able to fully explore the complex posterior distribution of the location of a narrow line, and thus provide valid statistical inference. Even with these computational tools, standard statistical quantities such as means and standard deviations cannot adequately summarize inference and standard testing procedures cannot be used to test for emission lines. In this paper, we use new efficient MCMC algorithms to fit the location of narrow emission lines, we develop new statistical strategies for summarizing highly multimodal distributions and quantifying valid statistical inference, and we extend the method of posterior predictive p-values proposed by Protassov et al. (2002) to test for the presence of narrow emission lines in X-ray spectra. We illustrate and validate our methods using simulation studies and apply them to the Chandra observations of the high redshift quasar PG1634+706.

  8. Intensity Variations of Narrow Bands of Solar UV Radiation during Descending Phases of SACs 21-23

    NASA Astrophysics Data System (ADS)

    Gigolashvili, M.; Kapanadze, N.

    2014-12-01

    The study of variations of four narrow bands of solar spectral irradiance (SSI) in the ultraviolet (UV) range for period 1981-2008 is presented. Observational data obtained by space-flight missions SORCE, UARS, SME and daily meanings of international sunspot number (ISN) have been used. The investigated data cover the decreasing phases of the solar activity cycles (SACs) 21, 22 and 23. We have revealed a peculiar behavior of intensity variability of some solar ultraviolet spectral lines originated in the solar chromospheres for period corresponding to the declining phase of the solar cycle 23. It is found that variability of emission of different solar spectral narrow bands (289.5 nm, 300.5 nm) does not agree equally well with ISN variability during decreasing phase of the solar activity cycle 23. The negative correlations between total solar irradiance and the solar spectral narrow bands of UV emission (298.5 nm, 300.5 nm) had been revealed. The existence of the negative correlation can be explained by the sensitivity of SSI of some emission lines to the solar global magnetic field.

  9. 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

  10. 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.

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

    PubMed

    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

  12. 47 CFR 80.361 - Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...coast stations for narrow-band direct-printing (NBDP) and data transmissions....

  13. 47 CFR 80.361 - Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...coast stations for narrow-band direct-printing (NBDP) and data transmissions....

  14. 47 CFR 80.361 - Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...coast stations for narrow-band direct-printing (NBDP) and data transmissions....

  15. 47 CFR 80.361 - Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...coast stations for narrow-band direct-printing (NBDP) and data transmissions....

  16. 47 CFR 80.361 - Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...Frequencies for narrow-band direct-printing (NBDP), radioprinter and data transmissions...coast stations for narrow-band direct-printing (NBDP) and data transmissions....

  17. Line-by-line narrow-band statistical model calculations for H2O

    Microsoft Academic Search

    J. M. Hartmann; R. Levi di Leon; J. Taine

    1984-01-01

    Line by line (LBL) calculations are performed to generate hot-band lines of H2O vapor from spectroscopic cold-band data. The data bases employed account for transitions of levels from 000-010, and a narrow band statistical model is defined using transitions at 25\\/cm intervals. Approximations are made of the hot-band data and compared with the experimental spectra for the 1000-4200\\/cm, 900-1500 K,

  18. Susceptibility of CMOS IC Devices Under Narrow-Band High Power Electromagnetic Waves by Magnetron

    Microsoft Academic Search

    J. I. Hong; S. M. Hwang; C. S. Huh

    2009-01-01

    We investigated the damage effects of CMOS IC devices manufactured using three different technologies under narrow-band high power electromagnetic (NB-HPEM) waves by magnetron. The output of NB-HPEM waves was controlled from 0 to 1 kW, and the narrow-band operating frequency was 2, 460±50 MHz. The NB-HPEM waves were propagated into a closed-ended standard rectangular waveguide for 1 s. During our

  19. Tolerability of magnifying narrow band imaging endoscopy for esophageal cancer screening

    PubMed Central

    Yamasaki, Yasushi; Takenaka, Ryuta; Hori, Keisuke; Takemoto, Koji; Kawano, Seiji; Kawahara, Yoshiro; Okada, Hiroyuki; Fujiki, Shigeatsu; Yamamoto, Kazuhide

    2015-01-01

    AIM: To compare the tolerability of magnifying narrow band imaging endoscopy for esophageal cancer screening with that of lugol chromoendoscopy. METHODS: We prospectively enrolled and analyzed 51 patients who were at high risk for esophageal cancer. All patients were divided into two groups: a magnifying narrow band imaging group, and a lugol chromoendoscopy group, for comparison of adverse symptoms. Esophageal cancer screening was performed on withdrawal of the endoscope. The primary endpoint was a score on a visual analogue scale for heartburn after the examination. The secondary endpoints were scale scores for retrosternal pain and dyspnea after the examinations, change in vital signs, total procedure time, and esophageal observation time. RESULTS: The scores for heartburn and retrosternal pain in the magnifying narrow band imaging group were significantly better than those in the lugol chromoendoscopy group (P = 0.004, 0.024, respectively, ANOVA for repeated measures). The increase in heart rate after the procedure was significantly greater in the lugol chromoendoscopy group. There was no significant difference between the two groups with respect to other vital sign. The total procedure time and esophageal observation time in the magnifying narrow band imaging group were significantly shorter than those in the lugol chromoendoscopy group (450 ± 116 vs 565 ± 174, P = 0.004, 44 ± 26 vs 151 ± 72, P < 0.001, respectively). CONCLUSION: Magnifying narrow band imaging endoscopy reduced the adverse symptoms compared with lugol chromoendoscopy. Narrow band imaging endoscopy is useful and suitable for esophageal cancer screening periodically. PMID:25759551

  20. The Power Spectrum of a Narrow Band Noise Passed through a Nonlinear Impedance Element

    Microsoft Academic Search

    John L. McLucas; Richard C. Raymond

    1951-01-01

    The power spectrum of the current flowing through a nonlinear impedance element excited by a narrow band of noise centered at 1.6 mc has been measured experimentally from the audio range through the sixth harmonic band. A noise having the spectral shape of an error function with a standard deviation of 3.8 kc was generated by passing the current from

  1. Some advantages of wide over narrow band signals in the search for extraterrestrial intelligence \\/SETI

    Microsoft Academic Search

    P. F. Clancy

    1980-01-01

    The present interest in the search for narrow-band signals in connection with SETI as well as its reasons and implications are considered. As an alternative, and considering the advantages of spread spectrum techniques in terms of higher communications capacity, the use of a wide-band transmission strategy is examined. The effects of dispersion by the interstellar medium and its use for

  2. ZEN2: a narrow J-band search for z ~ 9 Ly? emitting galaxies directed towards three lensing clusters

    NASA Astrophysics Data System (ADS)

    Willis, J. P.; Courbin, F.; Kneib, J.-P.; Minniti, D.

    2008-03-01

    We present the results of a continuing survey to detect Ly? emitting galaxies at redshifts z ~ 9: the `z equals nine' (ZEN) survey. We have obtained deep VLT Infrared Spectrometer and Array Camera observations in the narrow J-band filter NB119 directed towards three massive lensing clusters: Abell clusters 1689, 1835 and 114. The foreground clusters provide a magnified view of the distant Universe and permit a sensitive test for the presence of very high redshift galaxies. We search for z ~ 9 Ly? emitting galaxies displaying a significant narrow-band excess relative to accompanying J-band observations that remain undetected in Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) optical images of each field. No sources consistent with this criterion are detected above the unlensed 90 per cent point-source flux limit of the narrow-band image, FNB = 3.7 × 10-18ergs-1cm-2. To date, the total coverage of the ZEN survey has sampled a volume at z ~ 9 of approximately 1700 comoving Mpc3 to a Ly? emission luminosity of 1043ergs-1. We conclude by considering the prospects for detecting z ~ 9 Ly? emitting galaxies in light of both observed galaxy properties at z < 7 and simulated populations at z > 7.

  3. Narrow-band electrons in transition-metal oxides

    Microsoft Academic Search

    John B. Goodenough

    1967-01-01

    Experiments on LaCoO3 demonstrate that crystal-field theory and band theory describe two thermodynamically different electronic phases. For an integral number of electrons per atom, the phase transition is first-order. The critical parameter is an overlap integral, which may be either a cation-cation or a cation-anion-cation overlap integral. Intra-atomic exchange and electron-phonon interactions contribute significantly to electron localization. The characteristic feature

  4. 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.

  5. Frequency reconfigurable wide to narrow band monopole with slotted ground plane antenna

    Microsoft Academic Search

    H. A. Majid; M. K. A. Rahim; M. R. Hamid; M. F. Ismail; F. Malek

    2012-01-01

    A frequency reconfigurable wide to narrow band antenna is presented. The proposed antenna is a combination of a monopole antenna (MA) and a microstrip slot antenna (MSA). The MA produces a wide frequency band from 1.66 to 4.93?GHz, and the MSA produces three different frequency bands resonating at 3.02, 3.89, and 4.56?GHz. Simulated and measured results are used to validate

  6. 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).

  7. Mechanical filtering for narrow-band hearing in the weta.

    PubMed

    Lomas, Kathryn; Montealegre-Z, Fernando; Parsons, Stuart; Field, Larry H; Robert, Daniel

    2011-03-01

    This paper constitutes a major attempt to associate tympanic deflections with the mechanoreceptor organ location in an acoustic insect. The New Zealand tree weta (Hemideina thoracica) has tympanal ears located on each of the prothoracic tibiae. The tympana exhibit a sclerotized oval plate, membranous processes bulging out from the tibial cuticle and many loosely suspended ripples. We used microscanning laser Doppler vibrometry to determine how such a tympanal membrane vibrates in response to sound and whether the sclerotized region plays a role in hearing. The tympanum displays a single resonance at the calling frequency of the male, an unusual example of an insect tympana acting as a narrow bandpass filter. Both tympana resonate in phase with the stimulus and with each other. Histological sections show that the tympanal area is divided into two distinct regions, as in other ensiferans. An oval plate lies in the middle of a thickened region and is surrounded by a transparent and uniformly thin region. It is hinged dorsally to the tympanal rim and thus resembles the model of a 'hinged flap'. The thickened region appears to act as a damping mass on the oscillation of the thin region, and vibration displacement is reduced in this area. The thinner area vibrates with higher amplitude, inducing mechanical pressure on the dorsal area adjacent to the crista acustica. We present a new model showing how the thickened region might confer a mechanical gain onto the activation of the crista acustica sensory neurons during the sound-induced oscillations. PMID:21307064

  8. Optical narrow-band filters using optical amplification with distributed feedback

    Microsoft Academic Search

    K. Magari; H. Kawaguchi; K. Oe; M. Fukuda

    1988-01-01

    Amplification characteristics of the distributed feedback laser amplifiers are studied. The amplifier has a narrow, single frequency gain-bandwidth and the gain maximum frequency tunability. With these advantages, the amplifier can be applied as an optical narrow-band filter. This filter has optical frequency selectivity with an extinction ratio of better than -15 dB for two optical inputs separated by 9.8 GHz

  9. 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

  10. Sano's capillary pattern classification for narrow-band imaging of early colorectal lesions.

    PubMed

    Uraoka, Toshio; Saito, Yutaka; Ikematsu, Hiroaki; Yamamoto, Kazuhide; Sano, Yasushi

    2011-05-01

    Narrow-band imaging enhances visualization of the mucosal surface structure and vascular network and helps to increase the visibility of neoplasia by improving contrast. Sano and his colleagues first reported its efficacy for endoscopic use in the gastrointestinal tract and later proposed a sequential classification of the mucosal vascular network patterns according to histopathological categories. Sano's 'capillary pattern classification' was established to facilitate diagnosis of early colorectal lesions on a step-by-step basis. This review focuses on the utility and effectiveness of Sano's capillary pattern classification when examining early colorectal lesions using narrow-band imaging. PMID:21535215

  11. Motional Narrowing and Ergodic Bands in Excited Superdeformed States of {sup 194}Hg

    SciTech Connect

    Lopez-Martens, A. [C.S.N.S.M, IN2P3-CNRS, Batiment 104-108, 91405 Orsay (France); Doessing, T.; Herskind, B. [Niels Bohr Institute, DK-2100, Copenhagen (Denmark); Khoo, T. L.; Lauritsen, T.; Carpenter, M. P.; Janssens, R. V. F.; Hackman, G. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Matsuo, M. [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Lee, I-Y.; Macchiavelli, A. O. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Vigezzi, E. [INFN Sezione di Milano and Dipartimento di Fisica, Universita di Milano, Via Celoria 16, 20133 Milano (Italy); Yoshida, K. [Institue for Natural Science, Nara University, Nara 631-8502 (Japan)

    2008-03-14

    The E{sub {gamma}}-E{sub {gamma}} coincidence spectra from the electromagnetic decay of excited superdeformed states in {sup 194}Hg reveal surprisingly narrow ridges, parallel to the diagonal. A total of 100-150 excited bands are found to contribute to these ridges, which account for nearly all the unresolved E2 decay strength. Comparison with theory suggests that these excited bands have many components in their wave functions, yet they display remarkable rotational coherence. This phenomenon can be explained in terms of the combination of shell effects and motional narrowing.

  12. 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.

  13. First-principles Wannier functions and effective lattice fermion models for narrow-band compounds

    Microsoft Academic Search

    I. V. Solovyev

    2006-01-01

    We propose a systematic procedure for constructing effective lattice fermion models for narrow-band compounds on the basis of first-principles electronic-structure calculations. The method is illustrated for the series of transition-metal (TM) oxides: SrVO3 , YTiO3 , V2O3 , and Y2Mo2O7 , whose low-energy properties are linked exclusively to the electronic structure of an isolated t2g band. The method consists of

  14. Narrow-band ultraviolet B and Conventional UVB phototherapy in Psoriasis: a Randomised Controlled Trial

    Microsoft Academic Search

    Yan Yuehua; Ahmad T. Khalaf; Zhai Xiaoxiang; Wang Xinggang

    The narrow-band (NB-UVB) was developed for use in phototherapy, as an alternative to a broad-band UVB source and to photochemotherapy, both of which have significant side effects and carry a risk of carcinogenesis. NB-UVB is a new phototherapy option that has proved to be particularly effective at clearing psoriasis vulgaris, with a reduced capacity to produce erythema. This study was

  15. Bandwidth enhancement of narrow band antennas exploiting adjoint-based geometry evolution

    Microsoft Academic Search

    Mohamed H. Bakr; Massoud Ghassemi; Nagula Sangary

    2011-01-01

    We present a novel approach for extending the bandwidth of narrow band antennas exploiting geometry evolution. The geometry of the antenna is allowed to evolve subject to constraints on the shape feasibility. The sensitivities of the objective function with respect to the coordinates of a number of control vertices are utilized to determine how the shape evolves. We illustrate our

  16. Optimal Sampling and Processing of an Impulse Radio Signal Subjected to Narrow Band Interference

    Microsoft Academic Search

    John Nielsen

    2006-01-01

    In this paper the sampling, quantization and processing of an ultra-wideband (UWB) impulse radio (IR) receiver signal is considered when the propagation link is subjected to additive white Gaussian noise (AWGN) and narrow band interference (NBI) which may be non-Gaussian. The Neyman Pearson log likelihood ratio formulation results in receiver processing that consists of a Generalized Matched Filter (GMF) and

  17. Narrow-band interference excision in spread spectrum systems using lapped transforms

    Microsoft Academic Search

    Michael J. Medley; Gary J. Saulnier; Pankaj K. Das

    1997-01-01

    In order to mitigate narrow-band interference in spread spectrum communications systems, novel communications receivers incorporating transform domain filtering techniques are designed. In this paper, lapped transforms are used to transform the received data signal to the transform domain wherein adaptive excision is performed. Transform domain detection algorithms, which yield bit decisions based on the remaining signal energy, are analyzed and,

  18. Passive tracking and detection of underwater narrow-band acoustical spectral signatures

    Microsoft Academic Search

    J. Sildam

    2008-01-01

    Tracking, detection and classification of targets is complicated in presence of multiple targets located at close or overlapping bearings. Assuming that the respective targets exhibit unique spectral signatures, which include narrow-band (NB) tonals and associated harmonics, this problem is addressed in several steps using conventionally beam-formed array data. The first two include detection of signals and associated bearings, followed by

  19. Observation of Narrow-Band Noise Accompanying the Breakdown of Insulating States in High Landau Levels

    E-print Network

    Eisenstein, Jim

    in the quantum Hall regime [13]. Noise accompanying RIQHE breakdown has been ob- served in four different GaAs=AlGaAs heterostructures. We focus here on a 30 nm GaAs quantum well containing a 2DES with density ns 2:91011 cmÿ2Observation of Narrow-Band Noise Accompanying the Breakdown of Insulating States in High Landau

  20. Rejection of unknown multiple narrow band disturbances -A direct adaptive control approach

    E-print Network

    Paris-Sud XI, Université de

    Rejection of unknown multiple narrow band disturbances - A direct adaptive control approach I application of several unknown time varying sinusoidal disturbances. Index Terms-- direct adaptive control) of unknown disturbances without measuring them. The common framework is the assumption that the distur- bance

  1. Facile doping of anionic narrow-band-gap conjugated polyelectrolytes during dialysis.

    PubMed

    Mai, Cheng-Kang; Zhou, Huiqiong; Zhang, Yuan; Henson, Zachary B; Nguyen, Thuc-Quyen; Heeger, Alan J; Bazan, Guillermo C

    2013-12-01

    PCPDTBTSO3 K, an anionic, narrow-band-gap conjugated polyelectrolyte, was found to be doped after dialysis. The proposed doping mechanism involves protonation of the polymer backbone, followed by electron transfer from a neutral chain, to generate radical cations, which are stabilized by the pendant sulfonate anions. Formation of polarons is supported by spectroscopy and electrical-conductivity measurements. PMID:24281883

  2. Semiconductor waveguide inversion in disordered narrow band-gap M. J. Gilbert,a)

    E-print Network

    Gilbert, Matthew

    process, in dif- ferent III­V semiconductor hetrostructures GaAs and InAs , remains possibleSemiconductor waveguide inversion in disordered narrow band-gap materials M. J. Gilbert,a) R. Akis in a coupled semiconductor waveguide structure in III­V materials. However, to this point, investigations have

  3. Very narrow-band ultraviolet photodetection based on strained M-plane Sandip Ghosha

    E-print Network

    Ghosh, Sandip

    system which is also sensitive to the state of polarization of the incident light. This added region is limited to a few nanometers, representing high-quality-factor, narrow-band detection together with polarization sensitivity. Both features are obtained by utilizing a polarization-sensitive photodectector

  4. Monte Carlo Simulation of Radiation in Gases with a NarrowBand Model

    E-print Network

    Dufresne, Jean-Louis

    Monte Carlo Simulation of Radiation in Gases with a Narrow­Band Model and a Net, Germany. published in ASME Journal of Heat Transfer, May 1996, pp.401­407 Abstract The Monte Carlo method with the Monte Carlo method : numerical efficiency becomes independent of optical thickness, strongly non uniform

  5. Redistribution of atomic Rydberg states by tunable narrow band picosecond far-infrared pulses.

    PubMed

    Raman, C; Decamp, M F; Bucksbaum, P

    1997-09-29

    We study the redistribution of Cesium atomic Rydberg states by intense, shaped, narrow-band pulses of millimeter radiation. The radiation source is a large-area photoconductive switch illuminated by a temporally shaped optical pulse. We will present our latest efforts to study atomic redistribution in the strong-field limit using these table-top THz sources. PMID:19373400

  6. Random thermal fatigue in fast breeder reactor: a narrow-band spectrum

    Microsoft Academic Search

    Hiroaki Tanaka; Michiko Toyoda

    1996-01-01

    Thermal fatigue crack growth in a fast breeder reactor is theoretically investigated with the aid of probabilistic fracture mechanics (PFM) under the conditions that (i) the temperature variation is a narrow-band stationary process and (ii) the crack grows owing only to the peak stress variation. First, a statistical property of residual life of the component with single crack is derived

  7. Deep narrow band imagery of the diffuse ISM in M33

    NASA Technical Reports Server (NTRS)

    Hester, J. Jeff; Kulkarni, Shrinivas R.

    1990-01-01

    Very deep narrow band images were obtained for several fields in the local group spiral galaxy M33 using a wide field reimaging Charge Coupled Device (CCD) camera on the 1.5 m telescope at Palomar Observatory. The reimaging system uses a 306 mm collimator and a 58 mm camera lens to put a 16 minute by 16 minute field onto a Texas Instruments 800 x 800 pixel CCD at a resolution of 1.2 arcseconds pixel (-1). The overall system is f/1.65. Images were obtained in the light of H alpha (S II) lambda lambda 6717, 6731, (O III) lambda 5007, and line-free continuum bands 100A wide, centered at 6450A and 5100A. Assuming a distance of 600 kpc to M33 (Humphreys 1980, Ap. J., 241, 587), this corresponds to a linear scale of 3.5 pc pixel (-1), and a field size of 2.8 kpc x 2.8 kpc. Researchers discuss the H alpha imagery of a field centered approx. equal to 8 minutes NE of the nucleus, including the supergiant HII region complex NGC 604. Two 2000 second H alpha images and two 300 second red continuum images were obtained of two slightly offset fields. The fields were offset to allow for discrimination between real emission and possible artifacts in the images. All images were resampled to align them with one of the H alpha frames. The continuum images were normalized to the line images using the results of aperture photometry on a grid of stars in the field, then the rescaled continuum data were directly subtracted from the line data.

  8. Reverberation decay functions for narrow bands obtained from filtered time-windowed room impulse responses.

    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

  9. SEARCHING FOR NARROW EMISSION LINES IN X-RAY SPECTRA: COMPUTATION AND METHODS Taeyoung Park,1

    E-print Network

    van Dyk, David

    SEARCHING FOR NARROW EMISSION LINES IN X-RAY SPECTRA: COMPUTATION AND METHODS Taeyoung Park,1 David of the high-redshift quasar PG 1634+706. Subject headinggs: methods: statistical -- quasars: emission lines 1 The detection and quantification of narrow emission lines in X-ray spectra is a challenging statistical task

  10. Enhanced potential for metabolic studies using narrow-band sensitized FT-IR microspectroscopy.

    PubMed

    Wetzel, D L

    2003-06-01

    The ability to detect and measure the relative concentration of deuterated substance found in tissue specimens is enhanced by adding a custom made-to-order 50 microm narrow MCT band that has an optimized response profile for the CD, ND and OH absorption bands. In the short range of interest it has a 2:1 signal advantage over the stock MCT detector and the steep cut off before the finger print region significantly diminishing the noise. The result is that levels of specific deuterated compounds experimentally administered to biological systems and dispersed by the host organism can be detected and measured The custom small target size narrow-band detector with increased signal and reduced noise enhances the potential for the use of FT-IR microspectoscopy as a novel way to study metabolism without the use of radioactive materials. PMID:12899458

  11. 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%.

  12. Full band atomistic modeling of homo-junction InGaAs band-to-band tunneling diodes including band gap narrowing

    NASA Astrophysics Data System (ADS)

    Cho, Woo-Suhl; Luisier, Mathieu; Mohata, Dheeraj; Datta, Suman; Pawlik, David; Rommel, Sean L.; Klimeck, Gerhard

    2012-02-01

    A homo-junction In0.53Ga0.47As tunneling diode is investigated using full-band, atomistic quantum transport approach based on a tight-binding model (TB) and the non-equilibrium Green's function formalism. Band gap narrowing (BGN) is included in TB by altering its parameters using the Jain-Roulston model [S. C. Jain and D. J. Roulston, Solid-State Electron. 34, 453 (1991)]. BGN is found to be critical in the determination of the current peak and the second turn-on in the forward bias region. Empirical excess current that mimics additional recombination paths must be added to the calculation to model the diode behavior in the valley current region. Overall, the presented model reproduces experimental data well.

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

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Special requirements for narrow-band direct-printing (NB-DP) equipment. 80.219 Section 80.219 Telecommunication...80.219 Special requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP and data...

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

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Special requirements for narrow-band direct-printing (NB-DP) equipment. 80.219 Section 80.219 Telecommunication...80.219 Special requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP and data...

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

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Special requirements for narrow-band direct-printing (NB-DP) equipment. 80.219 Section 80.219 Telecommunication...80.219 Special requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP and data...

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

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...requirements for narrow-band direct-printing (NB-DP) equipment. 80.219 ...requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP...Recommendation M.476-5, “Direct-Printing Telegraph Equipment in the Maritime...

  17. 47 CFR 80.219 - Special requirements for narrow-band direct-printing (NB-DP) equipment.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...requirements for narrow-band direct-printing (NB-DP) equipment. 80.219 ...requirements for narrow-band direct-printing (NB-DP) equipment. NB-DP...Recommendation M.476-5, “Direct-Printing Telegraph Equipment in the Maritime...

  18. A narrow-band search for extraterrestrial intelligence (SETI) using the interstellar contact channel hypothesis

    Microsoft Academic Search

    D. G. Blair; R. P. Norris; E. R. Troup; R. Twardy; K. J. Wellington; A. J. Williams; A. E. Wright; M. G. Zadnik

    1992-01-01

    A search is reported for narrow spectral line emission from 176 targets (including 166 stars and seven globular clusers) at the hypothesized 'interstellar communications channel' frequency of 4.462336275 GHz (= pi times the neutral hydrogen line at 1.42 GHz) using the Parkes Radio telescope. The frequency was Doppler corrected for the solar barycenter, target barycenter, and cosmic microwave background (CMB)

  19. 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.

  20. 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.

  1. Narrow Band Ratio Vegetation Indices and Itsrelationships With Rice Agronomic Variables

    NASA Astrophysics Data System (ADS)

    Wang, Fumin; Huang, Jingfeng

    The present study aims to determine spectral bands that are best suited for characterizing rice agronomic variables. The data for this study came from ground-level hyperspectral reflectance measurements of rice at different stage. Reflectance was measured in discrete narrow bands between 350 and 2500 nm. Observed rice agronomic variables included leaf area index (LAI), wet biomass (WBM including aboveground wet biomass-AGWBM, leaf wet biomass-LWBM, stem wet biomass-SWBM), and dry biomass(DBM: including aboveground dry biomass-AGDBM, leaf dry biomass-LDBM, stem dry biomass.) Firstly, narrow band ratio vegetation index (NBRVI) involving all possible two bands combinations of discrete channels were tested. The second part of the paper describes a rigorous search procedure to identify the best NBRVI predictors of rice agronomic variables. Special narrow band lambda (?1) versus lambda (?2) plots of R2 values illustrates the most effective wavelength combinations (?1 and ?2) and band-widths (??1 and ??2) for predicting rice agronomic variables at different development stages. The best of the NBRVI models explained 58% to 83% variability rice agronomic variables at different development stage. A strong relationship with rice agronomic variables is located in red-edge, 700 nm to 750 nm, the longer portion of red (650nm to 700nm), the shorter portion of green (500nm to 550nm), a particular portion of NIR (800nm to 850nm). They are followed by moisture-sensitive NIR(1150nm to 1200nm), and two portions of SWIR (1600nm to 1650nm).

  2. First-principles study of direct and narrow band gap semiconducting ?-CuGaO2

    NASA Astrophysics Data System (ADS)

    Nguyen, Manh Cuong; Zhao, Xin; Wang, Cai-Zhuang; Ho, Kai-Ming

    2015-04-01

    Semiconducting oxides have attracted much attention due to their great stability in air or water and the abundance of oxygen. Recent success in synthesizing a metastable phase of CuGaO2 with direct narrow band gap opens up new applications of semiconducting oxides as absorber layer for photovoltaics. Using first-principles density functional theory calculations, we investigate the thermodynamic and mechanical stabilities as well as the structural and electronic properties of the ?-CuGaO2 phase. Our calculations show that the ?-CuGaO2 structure is dynamically and mechanically stable. The energy band gap is confirmed to be direct at the ? point of Brillouin zone. The optical absorption occurs right at the band gap edge and the density of states near the valance band maximum is large, inducing an intense absorption of light as observed in experiment.

  3. Continuous distribution of defect states and band gap narrowing in neutron irradiated GaAs

    SciTech Connect

    Fleming, R. M.; Lang, D. V.; Seager, C. H.; Bielejec, E.; Patrizi, G. A.; Campbell, J. M. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1415 (United States)

    2010-06-15

    We find that fast neutron irradiated n- and p-GaAs diodes both show a broad feature in deep level transient spectroscopy (DLTS) previously studied primarily in n-GaAs and termed the ''U-band.'' The high temperature edge of the broad DLTS feature cuts off at the same temperature in both n- and p-GaAs suggesting that the cut off is due to the DLTS behavior expected for a continuous density of defect states that spans midgap. The band gap implied by the DLTS midgap cut off is 1.36 eV, as compared to the bulk GaAs band gap 1.52 eV. Band gap narrowing is consistent with previous measurements of lattice expansion in neutron irradiated GaAs. This leads to a model of defect cascades that are regions of narrowed band gap with defect levels that are inhomogeneously broadened. We observe, in addition, that the damage cascades are surrounded by large Coulomb barriers that prevent the complete filling of traps in the damaged regions.

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

    Microsoft Academic Search

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

    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

  5. Audiogram of a harbor porpoise (Phocoena phocoena) measured with narrow-band frequency-modulated signals

    Microsoft Academic Search

    Ronald A. Kastelein; Paulien Bunskoek; Monique Hagedoorn; Whitlow W. L. Au; Dick de Haan

    2002-01-01

    The underwater hearing sensitivity of a two-year-old harbor porpoise was measured in a pool using standard psycho-acoustic techniques. The go\\/no-go response paradigm and up–down staircase psychometric method were used. Auditory sensitivity was measured by using narrow-band frequency-modulated signals having center frequencies between 250 Hz and 180 kHz. The resulting audiogram was U-shaped with the range of best hearing (defined as

  6. Performance Analysis of Narrow-Band Interference Rejection Techniques in DS Spread-Spectrum Systems

    Microsoft Academic Search

    RONALD A. ILTIS; LAURENCE B. MILSTEIN

    1984-01-01

    Linear least squares estimation (LLSE) techniques can provide an effective means of suppressing narrow-band interference in direct sequence (DS) spread-spectrum systems. In the results presented here, analytical expressions for bit error rate are derived for two DS spread-spectrum systems under the conditions of either tone or narrowband Gaussian interference. It is shown that the most common LLSE filter design can

  7. Performance advantage of complex LMS for controlling narrow-band adaptive arrays

    Microsoft Academic Search

    L. Horowitz; K. Senne

    1981-01-01

    In narrow-band adaptive-array applications, the mean-square convergence of the discrete-time real least mean-square (LMS) algorithm is slowed by image-frequency noises generated in the LMS loops. The complex LMS algorithm proposed by Widrow et al. is shown to eliminate these noises, yielding convergence of the mean-squared error (MSE) at slightly over twice the rate. This paper includes a comprehensive analysis of

  8. Laboratory study of wave and turbulence characteristics in narrow-band irregular breaking waves

    Microsoft Academic Search

    Francis C. K Ting

    2002-01-01

    Wave elevations and water particle velocities were measured in a laboratory surf zone created by the breaking of a narrow-band irregular wave train on a 1\\/35 plane slope. The incident waves form wave groups that are strongly modulated. It is found that the waves that break close to the shoreline generally have larger wave-height-to-water-depth ratios before breaking than the waves

  9. Imaging of the PAH Emission Bands in the Orion Bar

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse; Harker, David; Rank, David; Temi, Pasqiale; Morrison, David (Technical Monitor)

    1994-01-01

    The infrared spectrum of many planetary nebulae, HII regions, galactic nuclei, reflection nebulae, and WC stars are dominated by a set of narrow and broad features which for many years were called the "unidentified infrared bands". These bands have been attributed to several carbon-rich molecular species which all contain only carbon and hydrogen atoms, and fall into the class of PAH molecules or are conglomerates of PAH skeletons. If these bands are from PAHs, then PAHs contain 1-10% of the interstellar carbon, making them the most abundant molecular species in the interstellar medium after CO. From ground based telescopes, we have studied the emission bands assigned to C-H bond vibrations in PAHs (3.3, 11.3 microns) in the Orion Bar region, and showed that their distribution and intensities are consistent with a quantitative PAH model. We have recently obtained spectral images of the Orion Bar from the KAO at 6.2 and 7.7 microns using a 128 x 128 Si:Ga array camera in order to study the C-C modes of the PAH molecules. We will show these new data along with our existing C-H mode data set, and make a quantitative comparison of the data with the existing PAH model.

  10. 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.

  11. 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.

  12. LASERS: Narrow-band double-pass superluminescent diodes emitting at 1060 nm

    Microsoft Academic Search

    A. A. Lobintsov; M. V. Perevozchikov; M. V. Shramenko; S. D. Yakubovich

    2009-01-01

    Experimental data are presented which show that double-pass superluminescent diodes (SLDs) with fibre Bragg grating (FBG) based spectrally selective external reflectors offer emission linewidths in the range 0.1-1.0 nm, i.e., one to two orders of magnitude narrower in comparison with conventional SLDs and considerably broader in comparison with single-frequency semiconductor lasers. Their optical power at the single-mode fibre output reaches

  13. Narrow-band double-pass superluminescent diodes emitting at 1060 nm

    Microsoft Academic Search

    A A Lobintsov; M V Perevozchikov; M V Shramenko; S D Yakubovich

    2009-01-01

    Experimental data are presented which show that double-pass superluminescent diodes (SLDs) with fibre Bragg grating (FBG) based spectrally selective external reflectors offer emission linewidths in the range 0.1-1.0 nm, i.e., one to two orders of magnitude narrower in comparison with conventional SLDs and considerably broader in comparison with single-frequency semiconductor lasers. Their optical power at the single-mode fibre output reaches

  14. Evolution of [O III] ?5007 Emission-line Profiles in Narrow Emission-line Galaxies

    NASA Astrophysics Data System (ADS)

    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] ?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.

  15. Optical narrow-band filters using optical amplification with distributed feedback

    SciTech Connect

    Magari, K.; Kawaguchi, H.; Oe, K.; Fukuda, M. (NTT Opto-Electronics Labs., Atsugi-shi, Kanagawa Prefecture, 243-01 (JP))

    1988-11-01

    Amplification characteristics of the distributed feedback laser amplifiers are studied. The amplifier has a narrow, single frequency gain-bandwidth and the gain maximum frequency tunability. With these advantages, the amplifier can be applied as an optical narrow-band filter. This filter has optical frequency selectivity with an extinction ratio of better than -15 dB for two optical inputs separated by 9.8 GHz and having different optical input powers. By using a multielectrode distributed feedback laser amplifier, the wide-range tunability of a gain maximum frequency (33.3 GHz) can be obtained while maintaining a constant gain and a constant gain-bandwidth. Optical frequency selection with an extinction ratio of better than -20 dB can be obtained for two optical inputs separated by 15.4 GHz and having the same input powers.

  16. On-sky characterisation of the VISTA NB118 narrow-band filters at 1.19 ?m

    NASA Astrophysics Data System (ADS)

    Milvang-Jensen, Bo; Freudling, Wolfram; Zabl, Johannes; Fynbo, Johan P. U.; Møller, Palle; Nilsson, Kim K.; McCracken, Henry Joy; Hjorth, Jens; Le Fèvre, Olivier; Tasca, Lidia; Dunlop, James S.; Sobral, David

    2013-12-01

    Observations of the high redshift Universe through narrow-band filters have proven very successful in the last decade. The 4-m VISTA telescope, equipped with the wide-field camera VIRCAM, offers a major step forward in wide-field near-infrared imaging, and in order to utilise VISTA's large field-of-view and sensitivity, the Dark Cosmology Centre provided a set of 16 narrow-band filters for VIRCAM. These NB118 filters are centered at a wavelength near 1.19 ?m in a region with few airglow emission lines. The filters allow the detection of H? emitters at z = 0.8, H? and [O iii] emitters at z ? 1.4, [O ii] emitters at z = 2.2, and Ly? emitters at z = 8.8. Based on guaranteed time observations of the COSMOS field we here present a detailed description and characterization of the filters and their performance. In particular we provide sky-brightness levels and depths for each of the 16 detector/filter sets and find that some of the filters show signs of some red-leak. We identify a sample of 2 × 103 candidate emission-line objects in the data. Cross-correlating this sample with a large set of galaxies with known spectroscopic redshifts we determine the "in situ" passbands of the filters and find that they are shifted by about 3.5 - 4 nm (corresponding to 30% of the filter width) to the red compared to the expectation based on the laboratory measurements. Finally, we present an algorithm to mask out persistence in VIRCAM data. Scientific results extracted from the data will be presented separately. Based on observations collected at the European Southern Observatory, Chile, as part of programme 284.A-5026 (VISTA NB118 GTO, PI Fynbo) and 179.A-2005 (UltraVISTA, PIs Dunlop, Franx, Fynbo, & Le Fèvre).

  17. 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

  18. Long baseline narrow-band radiointerferometry for space navigation. I. Interplanetary apparatus: Measurements of the coordinates of the Vega spacecraft

    Microsoft Academic Search

    V. A. Alekseev; V. I. Altunin; A. A. Antipenko; A. V. Biryukov; Eh. D. Gatélyuk; V. P. Davydov; A. F. Dement'ev; S. P. Ignatov; I. A. Knorin; N. A. Knyazev; U. F. Kolyuka; A. E. Kryukov; B. N. Lipatov; E. P. Molotov; V. A. Okmyanskij; V. A. Rudakov; A. S. Sizov; V. A. Stepan'yants; V. F. Tikhonov; I. D. Tserenin

    1989-01-01

    A series of experiments conducted in 1985 - 1986 is described, on the possibility of using the method of long-baseline narrow-band radiointerferometry for exact determinations of the trajectories of interplanetary space apparatus. From the tracked objects, the Vega spacecraft, the authors received narrow-band radio signals in the long-wavelength range 32 cm. The baseline of the interferometer had a length of

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

    PubMed

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

    2015-03-01

    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(1)S0 ? 6(3)P1 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. PMID:25832214

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

    SciTech Connect

    Matsuoka, Leo; Hashimoto, Masashi; Yokoyama, Keiichi [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7, Umemidai, Kizugawa, Kyoto 619-0215 (Japan)

    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}.

  1. Variable narrow-band transmission filters for spectrometry from space. 2. Fabrication process.

    PubMed

    Piegari, Angela; Bulir, Jiri; Krasilnikova Sytchkova, Anna

    2008-05-01

    The optical components described here are variable narrow-band transmission filters, where the transmittance peak varies with the position along the surface of the filter itself. They allow the construction of ultracompact and low-weight spectrometers for space applications. The theoretical behavior of graded filters has been already investigated by the authors, for imaging spectrometry of the Earth surface. The application of graded filters to miniaturized instruments for planetary missions (Mercury) is considered. Experimental results on the fabrication of small-dimension variable transmission filters operating over a wide spectrum, from visible to near infrared, are reported. PMID:18449238

  2. 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 [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    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)

  3. Locata Performance Evaluation in the Presence of Wide- and Narrow-Band Interference

    NASA Astrophysics Data System (ADS)

    Khan, Faisal A.; Rizos, Chris; Dempster, Andrew G.

    Classically difficult positioning environments often call for augmentation technology to assist the GPS, or more generally the Global Navigation Satellite System (GNSS) technology. The ground-based ranging technology offers augmentation, and even replacement, to GPS in such environments. However, like any other system relying on wireless technology, a Locata positioning network also faces issues in the presence of RF interference (RFI). This problem is magnified due to the fact that Locata operates in the licence-free 2·4 GHz Industrial, Scientific and Medical (ISM) band. The licence-free nature of this band attracts a much larger number of devices using a wider range of signal types than for licensed bands, resulting in elevation of the noise floor. Also, harmonics from out-of-band signals can act as potential interferers. WiFi devices operating in this band have been identified as the most likely potential interferer, due partially to their use of the whole ISM band, but also because Locata applications often also may use a wireless network. This paper evaluates the performance of Locata in the presence of both narrow- and wide-band interfering signals. Effects of received interference on both raw measurements and final solutions are reported and analysed. Test results show that Locata performance degrades in the presence of received interference. It is also identified that high levels of received interference can affect Locata carriers even if the interference is not in co-frequency situation with the affected carrier. Finally, Locata characteristics have been identified which can be exploited to mitigate RFI issues.

  4. 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.

  5. Digital analysis of narrow-band imagery of the Cygnus Loop

    NASA Astrophysics Data System (ADS)

    Hester, J. J.; Parker, R. A. R.; Dufour, R. J.

    1983-10-01

    Calibrated surface brightness and spectral line ratio maps which involve emission from six different ionic species are derived from the digital analysis of narrow passband direct imagery of a field in the southeast part of the Cygnus Loop SNR, and the spatial structure is categorized on the basis of the presence or absence of features in images isolating different emission lines. While features present in all emission lines are found to have spectral behavior consistent with steady flow shock model calculations for a range of v(s), the features present only in such 'hot' lines as the O III forbidden line 5007 A are found to account for relative intensities of that line greater than can be matched by steady flow model calculations.

  6. 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 ...

  7. Locally Optimally Emitting Clouds and the Narrow Emission Lines in Seyfert Galaxies

    Microsoft Academic Search

    Jason W. Ferguson; Kirk T. Korista; Jack A. Baldwin; Gary J. Ferland

    1997-01-01

    The narrow emission line spectra of active galactic nuclei are not accurately described by simple photoionization models of single clouds. Recent Hubble Space Telescope images of Seyfert 2 galaxies show that these objects are rich with ionization cones, knots, filaments, and strands of ionized gas. Here we extend to the narrow-line region the \\

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Near-infrared narrow-band imaging of gold?silica nanoshells in tumors

    PubMed Central

    Puvanakrishnan, Priyaveena; Park, Jaesook; Diagaradjane, Parmeswaran; Schwartz, Jon A.; Coleman, Chris L.; Gill-Sharp, Kelly L.; Sang, Kristina L.; Payne, J. Donald; Krishnan, Sunil; Tunnell, James W.

    2009-01-01

    Gold nanoshells (GNS) are a new class of nanoparticles that can be optically tuned to scatter or absorb light from the near-ultraviolet to near-infrared (NIR) region by varying the core (dielectric silica)?shell (gold) ratio. In addition to spectral tunability, GNS are inert and bioconjugatable, making them potential labels for in vivo imaging and therapy of tumors. We report the use of GNS as exogenous contrast agents for enhanced visualization of tumors using narrow-band imaging (NBI). NBI takes advantage of the strong NIR absorption of GNS to distinguish between blood and nanoshells in the tumor by imaging in narrow wavelength bands in the visible and NIR, respectively. Using tissue-simulating phantoms, we determined the optimum wavelengths to enhance contrast between blood and GNS. We then used the optimum wavelengths for ex vivo imaging of tumors extracted from human colon cancer xenograft bearing mice injected with GNS. Systemically delivered GNS accumulated passively in tumor xenografts by the enhanced permeability and retention (EPR) effect. Ex vivo NBI of tumor xenografts demonstrated heterogeneous distribution of GNS with a clear distinction from the tumor vasculature. The results of this study demonstrate the feasibility of using GNS as contrast agents to visualize tumors using NBI. PMID:19405772

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

    SciTech Connect

    Egorov, Vladimir V., E-mail: egorov@photonics.ru [Photochemistry Center, Russian Academy of Sciences, Moscow, 119421 (Russian Federation)

    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.

  14. Critical bandwidth determined by masking in the presence of two narrow-band noises.

    PubMed

    Ishigami, H; Suzuki, T; Isojima, G

    1995-01-01

    In this experiment, the critical band (CB)-widths were measured using two narrow-band noises (NBNs) with steep cut-off slopes as a masker, varying their spectral level and center-frequency. The following results were obtained: (i) The CB-widths at all center-frequencies were narrower than the classical CB-widths estimated by Zwicker et al [J Acoust Soc Am 29:548-557 (1957)], and decreased continuously toward the lower frequency at the center-frequencies below 500 Hz, though Zwicker's data were constant in the same range. These results barely coincided with the frequency dependence of the equivalent rectangular bandwidth (ERB) which was estimated from the shape of the auditory filter measured directly. (ii) Level dependence of masking noise in CB was constant beyond 20 dB of the masked threshold. This depends on the use of NBN as a masker. (iii) The CB was influenced by distortion products and off-frequency listening. Accordingly, the bandwidths might differ with the experimental method. PMID:7677630

  15. 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.

  16. [Study on the Spectral Characteristics of the Narrow-Band Filter in SHS].

    PubMed

    Luo, Hai-yan; Shi, Hai-liang; Li, Zhi-wei; Li, Shuang; Xiong, Wei; Hong, Jin

    2015-04-01

    The spectral response of spatial heterodyne spectroscopy (SHS) is determined by the spectrum property of narrow-band filter. As discussed in previous studies, the symmetric heterodyned interferogram of high frequency waves modulated by SHS and lack of sample lead to spectral confusion, which is associated with the true and ghost spectra. Because of the deviation from theoretical index of narrow-band filter in the process of coating, the boarded spectral response and middle wave shift are presented, and conditions in the theoretical Littrow wavelength made the effective wavelength range of SHS reduced. According to the measured curve of filter, a new wavenumber of zero spatial frequency can be reset by tunable laser, and it is easy for SHS to improve the spectral aliasing distortion. The results show that it is utilized to the maximum extent of the effective bandwidth by adjusting the grating angle of rotation to change the Littrow wavelength of the basic frequency, and the spectral region increased to 14.9 nm from original 12.9 nm. PMID:26197613

  17. The effect of timing noise on targeted and narrow-band coherent searches for continuous gravitational waves from pulsars

    E-print Network

    G. Ashton; D. I. Jones; R. Prix

    2015-03-27

    Most searches for continuous gravitational-waves from pulsars use Taylor expansions in the phase to model the spin-down of neutron stars. Studies of pulsars demonstrate that their electromagnetic (EM) emissions suffer from \\emph{timing noise}, small deviations in the phase from Taylor expansion models. How the mechanism producing EM emission is related to any continuous gravitational-wave (CW) emission is unknown; if they either interact or are locked in phase then the CW will also experience timing noise. Any disparity between the signal and the search template used in matched filtering methods will result in a loss of signal-to-noise ratio (SNR), referred to as `mismatch'. In this work we assume the CW suffers a similar level of timing noise to its EM counterpart. We inject and recover fake CW signals, which include timing noise generated from observational data on the Crab pulsar. Measuring the mismatch over durations of order $\\sim 10$ months, the effect is for the most part found to be small. This suggests recent so-called `narrow-band' searches which placed upper limits on the signals from the Crab and Vela pulsars will not be significantly affected. At a fixed observation time, we find the mismatch depends upon the observation epoch. Considering the averaged mismatch as a function of observation time, we find that it increases as a power law with time, and so may become relevant in long baseline searches.

  18. UNKNOWN MULTIPLE NARROW-BAND DISTURBANCE REJECTION IN HARD DISK DRIVESAN ADAPTIVE NOTCH FILTER AND PERFECT DISTURBANCE

    E-print Network

    Mofrad, Mohammad R. K.

    UNKNOWN MULTIPLE NARROW-BAND DISTURBANCE REJECTION IN HARD DISK DRIVES­AN ADAPTIVE NOTCH FILTER-band disturbances in a hard disk drive. An adaptive notch filter is developed to efficiently esti- mate INTRODUCTION The track following control in a hard disk drive (HDD) sys- tem aims at precisely regulating

  19. Narrow-band double-pass superluminescent diodes emitting at 1060 nm

    SciTech Connect

    Lobintsov, A A; Perevozchikov, M V; Shramenko, M V [Superlum Diodes Ltd., Moscow (Russian Federation); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

    2009-09-30

    Experimental data are presented which show that double-pass superluminescent diodes (SLDs) with fibre Bragg grating (FBG) based spectrally selective external reflectors offer emission linewidths in the range 0.1-1.0 nm, i.e., one to two orders of magnitude narrower in comparison with conventional SLDs and considerably broader in comparison with single-frequency semiconductor lasers. Their optical power at the single-mode fibre output reaches 5.0-8.0 mW, and can be raised to 50 mW using a semiconductor optical amplifier. (lasers)

  20. Evolution of [OIII]5007 emission-line profiles in narrow emission-line galaxies

    E-print Network

    Wang, J; Wei, J Y

    2011-01-01

    The AGN-host co-evolution issue is investigated here by focusing on the evolution of the [\\ion{O}{3}]$\\lambda5007$ emission-line profile. In order to simultaneously measure both [\\ion{O}{3}] line profile and circumnuclear stellar population in individual spectrum, a large sample of narrow emission-line galaxies is selected from the MPA/JHU SDSS DR7 catalog. By requiring that 1) the [\\ion{O}{3}] line signal-to-noise ratio is larger than 30, 2) the [\\ion{O}{3}] line width is larger than the instrumental resolution by a factor of 2, our sample finally contains 2,333 Seyfert galaxies/LINERs (AGNs), 793 transition galaxies, and 190 starforming galaxies. In additional 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 [...

  1. Narrow and broad band photoluminescence spectroscopy of cadmium zinc selenide semiconductor

    NASA Astrophysics Data System (ADS)

    Sweiti, Ayman

    2003-06-01

    In this dissertation I have used photoluminescence (PL) spectrometric analysis to measure the temperature dependence of the spectral features of the direct band gap semiconductor CdxZn1-xSe , for two nominal concentrations x = 0.25, 0.50, in the temperature range 25--300 K. The effective concentrations were obtained from analysis of the spectra. The parameters that describe the temperature dependence of the line width broadening have been evaluated using different models. The PL broadband characteristics of Cd0.22Zn0.78Se and Cd0.41Zn0.59Se are also investigated within the energy range 1.36--2.40 eV and temperature range 25--305 K. Two broad bands are observed, the higher energy band I centered at 1.991 and 1.773 eV, the lower energy band II centered at 1.844 and 1.705 eV for the two samples, respectively. The emission bands are attributed to donor-acceptor pair transitions. The energy scheme shows two donors and two acceptor levels, the binding energies of the donors for Cd 0.22Zn0.78Se are 29 and 208 meV below the conduction band, the binding energies of the acceptors 472 and 511 meV above the valence band. The binding energies of the donors for Cd0.41Zn 0.59Se are 27 and 137 meV, the binding energies of the acceptors 393 and 423 eV. A significant blue shift in energy with increasing temperature was observed for the lower energy band. The ionization temperatures for the deep donors are 279 and 287 K for Cd0.22Zn0.78Se and Cd0.41Zn0.59Se, respectively.

  2. First-principles Wannier functions and effective lattice fermion models for narrow-band compounds

    NASA Astrophysics Data System (ADS)

    Solovyev, I. V.

    2006-04-01

    We propose a systematic procedure for constructing effective lattice fermion models for narrow-band compounds on the basis of first-principles electronic-structure calculations. The method is illustrated for the series of transition-metal (TM) oxides: SrVO3 , YTiO3 , V2O3 , and Y2Mo2O7 , whose low-energy properties are linked exclusively to the electronic structure of an isolated t2g band. The method consists of three parts, starting from the electronic structure in the local-density approximation (LDA). (i) Construction of the kinetic-energy Hamiltonian using formal downfolding method. It allows us to describe the band structure close to the Fermi level in terms of a limited number of (unknown yet) Wannier functions (WFs), and eliminate the rest of the basis states. (ii) Solution of an inverse problem and construction of WFs for the given kinetic-energy Hamiltonian. Here, we closely follow the construction of the basis functions in the liner-muffin-tin-orbital (LMTO) method, and enforce the orthogonality of WFs to other bands. In this approach, one can easily control the contributions of the kinetic-energy term to the WFs. (iii) Calculation of screened Coulomb interactions in the basis of auxiliary WFs. The latter are defined as the WFs for which the kinetic-energy term is set to be zero. Meanwhile, the hybridization between TM d and other atomic states is preserved by the orthogonality condition to other bands. The use of auxiliary WFs is necessary in order to avoid the double counting of the kinetic-energy term, which is included explicitly in the model Hamiltonian. In order to calculate the screened Coulomb interactions we employed a hybrid approach. First, we evaluate the screening caused by the change of occupation numbers and the relaxation of the LMTO basis functions, using the conventional constraint-LDA approach, where all matrix elements of hybridization connecting the TM d orbitals and other orbitals are set to be zero. Then, we switch on the hybridization and evaluate the screening of on-site Coulomb interactions associated with the change of this hybridization in the random-phase approximation. The second channel of screening appears to be very important, and results in relatively small values of effective Coulomb interactions in the t2g band (of the order of 2-3eV , depending on the material). We discuss details of this screening and consider its band-filling dependence, frequency dependence, influence of the lattice distortion, proximity of other bands, as well as the effect of dimensionality of the model Hamiltonian.

  3. Ultra narrow band fiber optic Bragg grating filters for atmospheric water vapor measurements

    NASA Astrophysics Data System (ADS)

    Vann, Lelia Belle

    Optical fibers have revolutionized telecommunications. Much of the success of optical fiber lies in its near-ideal properties: low transmission loss, high optical damage threshold, and low optical nonlinearity. The photosensitivity of an optical fiber was accidentally discovered by Hill, et al. in 1978. However, the technological advances made in the field of photosensitive optical fibers are relatively recent. This fascinating technology of photosensitive fiber is based on the principle of a simple in-line all-fiber optical filter. It has been shown that the transmission spectrum of a fiber Bragg grating can be tailored by incorporating multiple phase-shift regions during the fabrication process. Phase shifts open up ultra narrowband transmission windows inside the stop band of the Bragg grating. As a specific application, this research is focused on applying this technology in future space-based water vapor DIfferential Absorption LIDAR (DIAL) systems to improve the performance of space-based LIDAR systems by rejecting the reflected solar background. The primary goal of this research effort was to demonstrate the feasibility of using ultra narrow band fiber optic Bragg grating filters for atmospheric water vapor measurements. Fiber Bragg gratings were fabricated such that two transmission filter peaks occurred and were tunable, one peak at a 946 nm water vapor absorption line and another peak at a region of no absorption. Both transmission peaks were in the middle of a 2.66-nm stop band. Experimental demonstration of both pressure and temperature tuning was achieved and characterization of the performance of several custom-made optical fiber Bragg grating filters was made. To our knowledge these are the first optical fiber gratings made in this frequency range and for this application. The bandwidth and efficiency of these filters were measured and then these measurements were compared with theoretical calculations using a piecewise matrix form of the coupled-mode equation. Finally, an ultra narrow band water vapor DIAL filter was characterized having two pass bands less than 8 pm and peak transmissions greater than 80 percent. Such fiber optic filters are now ready for integrating into space-based water vapor LIDAR systems. More broadly, these filters have the characteristics that will revolutionized satellite remote-sensing.

  4. 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.

  5. The GRB of 1999 January 23: Prompt emission and broad-band afterglow modeling

    NASA Astrophysics Data System (ADS)

    Corsi, A.; Piro, L.; Kuulkers, E.; Amati, L.; Antonelli, L. A.; Costa, E.; Feroci, M.; Frontera, F.; Guidorzi, C.; Heise, J.; in't Zand, J.; Maiorano, E.; Montanari, E.; Nicastro, L.; Pian, E.; Soffitta, P.

    2005-07-01

    We report on BeppoSAX simultaneous X- and ?-ray observations of the bright ?-ray burst (GRB) 990123. We present the broad-band spectrum of the prompt emission, including optical, X- and ?-rays, confirming the suggestion that the emission mechanisms at low and high frequencies must have different physical origins. We discuss the X-ray afterglow observed by the Narrow Field Instruments (NFIs) on board BeppoSAX and its hard-X-ray emission up to 60 keV several hours after the burst, in the framework of the standard fireball model. The effects of including an important contribution of inverse Compton scattering or modifying the hydrodynamics are studied.

  6. Full band atomistic modeling of homo-junction InGaAs band-to-band tunneling diodes including band gap narrowing

    E-print Network

    Rommel, Sean

    Full band atomistic modeling of homo-junction InGaAs band-to-band tunneling diodes including band Institute of Physics. Related Articles Degenerate p-doping of InP nanowires for large area tunnel diodes Appl. Phys. Lett. 99, 253105 (2011) Metal-oxide-oxide-metal granular tunnel diodes fabricated

  7. Polyp detection rates using magnification with narrow band imaging and white light

    PubMed Central

    Gilani, Nooman; Stipho, Sally; Panetta, James D; Petre, Sorin; Young, Michele A; Ramirez, Francisco C

    2015-01-01

    AIM: To compare the yield of adenomas between narrow band imaging and white light when using high definition/magnification. METHODS: This prospective, non-randomized comparative study was performed at the endoscopy unit of veteran affairs medical center in Phoenix, Arizona. Consecutive patients undergoing first average risk colorectal cancer screening colonoscopy were selected. Two experienced gastroenterologists performed all the procedures that were blinded to each other’s findings. Demographic details were recorded. Data are presented as mean ± SEM. Proportional data were compared using the ?2 test and means were compared using the Student’s t test. Tandem colonoscopy was performed in a sequential and segmental fashion using one of 3 strategies: white light followed by narrow band imaging [Group A: white light (WL) ? narrow band imaging (NBI)]; narrow band imaging followed by white light (Group B: NBI ? WL) and, white light followed by white light (Group C: WL ? WL). Detection rate of missed polyps and adenomas were evaluated in all three groups. RESULTS: Three hundred patients were studied (100 in each Group). Although the total time for the colonoscopy was similar in the 3 groups (23.8 ± 0.7, 22.2 ± 0.5 and 24.1 ± 0.7 min for Groups A, B and C, respectively), it reached statistical significance between Groups B and C (P < 0.05). The cecal intubation time in Groups B and C was longer than for Group A (6.5 ± 0.4 min and 6.5 ± 0.4 min vs 4.9 ± 0.3 min; P < 0.05). The withdrawal time for Groups A and C was longer than Group B (18.9 ± 0.7 min and 17.6 ± 0.6 min vs 15.7 ± 0.4 min; P < 0.05). Overall miss rate for polyps and adenomas detected in three groups during the second look was 18% and 17%, respectively (P = NS). Detection rate for polyps and adenomas after first look with white light was similar irrespective of the light used during the second look (WL ? WL: 13.7% for polyps, 12.6% for adenomas; WL ? NBI: 14.2% for polyps, 11.3% for adenomas). Miss rate of polyps and adenomas however was significantly higher when NBI was used first (29.3% and 30.3%, respectively; P < 0.05). Most missed adenomas were ? 5 mm in size. There was only one advanced neoplasia (defined by size only) missed during the first look. CONCLUSION: Our data suggest that the tandem nature of the procedure rather than the optical techniques was associated with the detection of additional polyps’ and adenomas. PMID:25992195

  8. Esophageal adenocarcinoma with white opaque substance observed by magnifying endoscopy with narrow band imaging.

    PubMed

    Yoshii, Shunsuke; Kato, Motohiko; Honma, Keiichiro; Fujinaga, Tetsuji; Tsujii, Yoshiki; Maekawa, Akira; Inoue, Takuya; Hayashi, Yoshito; Akasaka, Tomofumi; Shinzaki, Shinichiro; Nishida, Tsutomu; Iijima, Hideki; Tsujii, Masahiko; Morii, Eiichi; Takehara, Tetsuo

    2015-03-01

    White opaque substance (WOS) is observed in the gastric neoplasia of 0-IIa type using magnifying endoscopy with narrow band imaging (NBI-ME). Colonic and duodenal neoplasms with WOS have also been reported. Immunohistochemical examination with adipophilin reveals WOS in gastric neoplasms as lipid droplets, and WOS is specific for neoplasm with intestinal or gastrointestinal phenotype. We herein report a case of adenocarcinoma of the esophagogastric junction with WOS. A male patient in his sixties was found by esophagogastroduodenoscopy to have an esophageal elevated lesion. NBI-ME showed whitish deposits that looked similar to WOS in gastric neoplasms. The patient underwent endoscopic submucosal dissection and the lesion was resected in a single piece. This tumor had diffuse positivity for adipophilin and gastrointestinal phenotype. PMID:25041337

  9. 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.

  10. In-band pumped polarized, narrow-linewidth Er:YAG laser at 1645 nm.

    PubMed

    Wang, Mingjian; Meng, Junqing; Hou, Xia; Chen, Weibiao

    2014-10-20

    We report a polarized, narrow-linewidth Er:YAG laser operating at 1645 nm, in-band pumped by a continuous-wave (CW), narrowband 1532 nm fiber-coupled laser diode (LD). A maximum polarized continuous wave output power of 8.45 W was obtained, resulting in an optical conversion efficiency of 56% with respect to the absorbed pump power. The central wavelength was measured to be 1645.45 nm, with a full width at half-maximum of 0.13 nm. For Q-switched operation, pulse energy of 12 mJ at 100 Hz pulse repetition frequency and 95 ns pulse duration was yielded. To the best of our knowledge, this polarized pulse energy is the highest energy reported for a Q-switched Er:YAG laser pumped by a CW LD. PMID:25402806

  11. Mechanism of phase conjugation via stimulated Brillouin scattering in narrow band gap semiconductors

    NASA Astrophysics Data System (ADS)

    Singh, M.; Aghamkar, P.

    2008-03-01

    We develop a theoretical model to study optical phase conjugation via stimulated Brillouin scattering (OPC-SBS) in narrow band gap transversely magnetized semiconductors. Threshold value of pump electric field and reflectivity of the image radiation for the onset of OPC-SBS are estimated. The analysis is applied to both cases viz. centrosymmetric (CS) and non-centrosymmetric (NCS) crystals. Numerical estimates made for n-type InSb crystal at liquid nitrogen temperature duly irradiated by nanosecond pulsed 10.6 ?m CO2 laser shows that high OPC-SBS reflectivity (90%) can be achieved in NCS crystals at moderate pump electric fields if the crystal is used as an optical waveguide with relatively large interaction length (L = 5 mm) which proves its potential in practical applications such as fabrication of phase conjugate mirrors.

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

    SciTech Connect

    Kumar, Jitendra, E-mail: jkiitk@gmail.com, E-mail: akrsri@gmail.com; Kumar Srivastava, Amit, E-mail: jkiitk@gmail.com, E-mail: akrsri@gmail.com [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

    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.

  13. Generalized Lichen Nitidus Successfully Treated with Narrow-band UVB Phototherapy : Two Cases Report

    PubMed Central

    Do, Mi-Ok; Kim, Myoung-Ju; Kim, Seong-Hyun; Myung, Ki-Bum

    2007-01-01

    Lichen nitidus (LN) is an uncommon chronic inflammatory skin disease composed of numerous, tiny, shiny, flesh-colored papules that are predominantly observed on the chest, abdomen, glans penis and upper extremities. The distribution of LN is most often localized, but in some cases it can become generalized. Because LN tends to be asymptomatic and presents spontaneous resolution within several years, it usually does not require treatment except in symptomatic, persistent and generalized cases. We describe a 28-yr-old man and a 7-yr-old boy with generalized LN where both cases improved with narrow-band ultraviolet B (NB-UVB) phototherapy plus topical steroid ointment. Both patients noted improvement within the first three treatments and showed almost complete resolution after 18 and 20 treatments, respectively. NB-UVB phototherapy may be an effective alternative therapy for the treatment of generalized LN, even for those patients in their childhood. PMID:17297274

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

    NASA Astrophysics Data System (ADS)

    Kumar, Jitendra; Kumar Srivastava, Amit

    2014-04-01

    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 ?EBGN = Bn1/3 [1 - (nc/n)1/3], where B is the fitting parameter, n is carrier concentration, and nc is the critical density required for shrinkage onset. Its uniqueness lies in not only describing variation of ?EBGN correctly but also allowing deduction of nc automatically for several M-doped ZnO (M: Ga, Al, In, B, Mo) systems. The physical significance of the term [1 - (nc/n)1/3] is discussed in terms of carrier separation.

  15. Generalized lichen nitidus successfully treated with narrow-band UVB phototherapy: two cases report.

    PubMed

    Do, Mi-Ok; Kim, Myoung-Ju; Kim, Seong-Hyun; Myung, Ki-Bum; Choi, You-Won

    2007-02-01

    Lichen nitidus (LN) is an uncommon chronic inflammatory skin disease composed of numerous, tiny, shiny, flesh-colored papules that are predominantly observed on the chest, abdomen, glans penis and upper extremities. The distribution of LN is most often localized, but in some cases it can become generalized. Because LN tends to be asymptomatic and presents spontaneous resolution within several years, it usually does not require treatment except in symptomatic, persistent and generalized cases. We describe a 28-yr-old man and a 7-yr-old boy with generalized LN where both cases improved with narrow-band ultraviolet B (NB-UVB) phototherapy plus topical steroid ointment. Both patients noted improvement within the first three treatments and showed almost complete resolution after 18 and 20 treatments, respectively. NB-UVB phototherapy may be an effective alternative therapy for the treatment of generalized LN, even for those patients in their childhood. PMID:17297274

  16. 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

  17. Anomalous resistivity and the origin of heavy mass in the two-band Hubbard model with one narrow band

    SciTech Connect

    Kagan, M. Yu., E-mail: kagan@kapitza.ras.ru [Kapitza Institute for Physical Problems (Russian Federation); Val'kov, V. V. [Kirenskii Institute of Physics (Russian Federation)

    2011-07-15

    We search for marginal Fermi-liquid behavior in the two-band Hubbard model with one narrow band. We consider the limit of low electron densities in the bands and strong intraband and interband Hubbard interactions. We analyze the influence of electron polaron effect and other mechanisms of mass enhancement (related to momentum dependence of the self-energies) on the effective mass and scattering times of light and heavy components in the clean case (electron-electron scattering and no impurities). We find the tendency towards phase separation (towards negative partial compressibility of heavy particles) in the 3D case for a large mismatch between the densities of heavy and light bands in the strong-coupling limit. We also observe that for low temperatures and equal densities, the homogeneous state resistivity R(T) {approx} T{sub 2} behaves in a Fermi-liquid fashion in both 3D and 2D cases. For temperatures higher than the effective bandwidth for heavy electrons T > W{sub *}{sup h}, the coherent behavior of the heavy component is totally destroyed. The heavy particles move diffusively in the surrounding of light particles. At the same time, the light particles scatter on the heavy ones as if on immobile (static) impurities. In this regime, the heavy component is marginal, while the light one is not. The resistivity saturates for T > W{sub *}{sup h} in the 3D case. In 2D, the resistivity has a maximum and a localization tail due to weak-localization corrections of the Altshuler-Aronov type. Such behavior of resistivity could be relevant for some uranium-based heavy-fermion compounds like UNi{sub 2}Al{sub 3} in 3D and for some other mixed-valence compounds possibly including layered manganites in 2D. We also briefly consider the superconductive (SC) instability in the model. The leading instability is towards the p-wave pairing and is governed by the enhanced Kohn-Luttinger mechanism of SC at low electron density. The critical temperature corresponds to the pairing of heavy electrons via polarization of the light ones in 2D.

  18. Effects of spin--orbit interaction on optical properties of narrow-band semiconductor quantum wells

    NASA Astrophysics Data System (ADS)

    Isaev, Leonid

    2005-04-01

    We study effects of strong spin-orbit interaction on optical properties of narrow-gap semiconductor quantum films. Electron states in such materials (e.g. PbxSn/1-x/(S,Se,Te)) are well described by the two-band Kane model with the Dirac-type effective Hamiltonian [1]. It may be shown that electron dispersion in a film with identical boundaries still keeps spin degeneracy. In the present work we consider two types of (asymmetric) films with broken mirror symmetry: i) with nonequivalent boundaries, and {ii}) with a linear spatial variation of the forbidden band in the direction of epitaxial growth. It was shown that in both cases there is a noticeable spin-splitting of size-quantized subbands, strongly dependent on parameters in boundary conditions on film's surfaces. Under external illumination this results in an asymmetric distribution of photoexcited carriers in {k}-space, and therefore, in spin-polarized photocurrents. We also show that measurement of optical absorption coefficient may give direct information about the film surface structure. [1] J. O. Dimmock, G. B. Wright, Phys. Rev. {135}, A821 (1964). This work is supported by the Indiana 21st Century Research and Technology Fund.

  19. Locally Optimally-emitting Clouds and the Narrow Emission Lines in Seyfert Galaxies

    Microsoft Academic Search

    Jason W. Ferguson; Kirk T. Korista; Jack A. Baldwin; Gary J. Ferland

    1997-01-01

    The narrow emission line spectra of active galactic nuclei are not accurately\\u000adescribed by simple photoionization models of single clouds. Recent Hubble\\u000aSpace Telescope images of Seyfert 2 galaxies show that these objects are rich\\u000awith ionization cones, knots, filaments, and strands of ionized gas. Here we\\u000aextend to the narrow line region the ``locally optimally emitting cloud'' (LOC)\\u000amodel,

  20. Correlation between broad-band noise and frequency fluctuations of narrow-band noise in the charge-density wave in NbSe3

    Microsoft Academic Search

    I. Bloom; A. C. Marley; M. B. Weissman

    1994-01-01

    The broad-band noise (BBN) and the frequency fluctuations of the narrow-band noise (NBN) were simultaneously measured in small NbSe3 samples. The two variables were highly correlated. Some discrete switching events show up in both noises. When multiple NBN peaks were present, some large fluctuations appearing in the BBN did not appear in the frequency of the biggest NBN peak, indicating

  1. Characterizing the Atmospheres of Super-Earths and Hot-Jupiters with Narrow-Band Photometry

    NASA Astrophysics Data System (ADS)

    Colon, Knicole D.; Gaidos, E.; Wilson, P. A.; Ford, E. B.; Sing, D. K.; Ballester, G. E.; Desert, J.; Ehrenreich, D.; Fortney, J. J.; Lecavelier des Etangs, A.; Lopez-Morales, M.; Morley, C.; Pettitt, A.; Pont, F.; Vidal-Madjar, A.

    2014-01-01

    Nearly one thousand extrasolar planets have been discovered, but none are considered true analogs to solar system planets. Instead, we characterize some planets as “super-Earths” or “hot-Jupiters.” It has been possible to characterize the atmospheres of some of these planets via transit observations, which is a crucial stepping stone towards future studies of true solar system analogs. We present narrow-band photometry of several transiting planets, including the super-Earth GJ 1214b and the hot-Jupiters XO-2b and TrES-2b. For GJ 1214b, most studies find that the transmission spectrum is flat, which favors either a high mean molecular weight or cloudy/hazy hydrogen (H) rich atmosphere model. We observed seven transits of GJ 1214b through a narrow K-band (2.141 micron) filter with the Wide Field Camera on the 3.8 meter United Kingdom Infrared Telescope. We observed another five transits at 800-900 nm using tunable filters with the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) on the 10.4 meter Gran Telescopio Canarias (GTC). Our observations support a flat transmission spectrum for GJ 1214b, but we also find that a hydrogen-dominated upper atmosphere cannot be excluded. For hot-Jupiters, potassium has been predicted to be one of the strongest sources of opacity at optical wavelengths and has been previously detected in the atmospheres of XO-2b and TrES-2b. Using OSIRIS on the GTC, we observed three transits of XO-2b and two transits of TrES-2b in multiple bandpasses around the potassium absorption feature at 770 nm. Our technique is somewhat different than in previous studies, and we use our observations to constrain the amount of potassium in these exoplanet atmospheres. We consider how our studies set the stage for future investigations of true Earth and Jupiter analogs that have not yet been discovered.

  2. 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

  3. 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.

  4. A narrow-band tunable diode laser system with grating feedback, and a saturated absorption spectrometer for Cs and Rb

    Microsoft Academic Search

    K. B. MacAdam; A. Steinbach; C. Wieman

    1992-01-01

    Detailed instructions for the construction and operation of a diode laser system with optical feedback are presented. This system uses feedback from a diffraction grating to provide a narrow-band continuously tuneable source of light at red or near-IR wavelengths. These instructions include machine drawings for the parts to be constructed, electronic circuit diagrams, and prices and vendors of the items

  5. Design of optical thin film systems for ultraviolet narrow-band interference filters based on needle optimization technique

    NASA Astrophysics Data System (ADS)

    Peng, Guanliang; Yang, Jiankun; Jia, Honghui; Chang, Shengli; Yang, Juncai

    2007-11-01

    Solar blind ultraviolet communication systems can provide short to medium range non line-of-sight and line-of-sight links which are covert and insensitive to meteorological conditions. These unique properties endow solar blind ultraviolet communication systems increasing applications. While optical filters are key components of these solar blind ultraviolet communication systems. Although filters can be designed in different forms, thin-film interference narrow-band filters are widely adopted. In this paper, we make use of NCNBIF, which was so-called nonconventional narrow-band interference filters proposed by Jerzy Ciosek firstly, to design ultraviolet narrow-band interference filters. Generally, classical narrow-band interference dielectric filters, such as Fabry-Pérot filters, have a half-wave-thickness spacer layer. In contrast with a classical interference filter, the NCNBIF does not have a half-wave-thickness spacer layer. This spacer layer of NCNBIF consists of two different materials. This new kind of film system (NCNBIF) is synthesized by using needle optimization technique, and possesses desired spectral characteristics.

  6. 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 ...

  7. Observations of an Intense Field-Aligned Thermal Ion Flow and Associated Intense Narrow Band Electric Field Oscillations

    Microsoft Academic Search

    Edgar A. Bering; Michael C. Kelley; Forrest S. Mozer

    1975-01-01

    An intense downward field-aligned thermal ion flow and intense narrow band waves with frequencies just below the local ion gyrofrequency have been observed at the equatorward edge of an auroral arc. The magnitude and direction of the field-aligned current required by the measured dc electric field pattern are consistent with the ion flow measurements and with a differential drift between

  8. Suppression of Narrow-Band Interference in a PN Spread-Spectrum Receiver Using a CTD-Based Adaptive Filter

    Microsoft Academic Search

    G. Saulnier; P. Das; L. Milstein

    1984-01-01

    Analytical results have shown that adaptive filtering can be a powerful tool for the rejection of narrow-band interference in a spreadspectrum receiver. However, the complexity of adaptive filtering hardware has hindered the experimental verification of these results. This paper describes a new adaptive filter architecture for implementing the Widrow-Hoff LMS algorithm while using only two multipliers regardless of filter order.

  9. Absorption of Narrow-Gap HgCdTe Near the Band Edge Including Nonparabolicity and the Urbach Tail

    E-print Network

    Flatte, Michael E.

    Absorption of Narrow-Gap HgCdTe Near the Band Edge Including Nonparabolicity and the Urbach Tail, USA. 6.--e-mail: yonchang@uic.edu An analytical model describing the absorption behavior of Hg1-x. This model smoothly fits experimental absorption coefficients over energies ranging from the Urbach tail

  10. Narrow-band deep-ultraviolet light emitting device using Al{sub 1-x}Gd{sub x}N

    SciTech Connect

    Kita, Takashi; Kitayama, Shinya; Kawamura, Masashi; Wada, Osamu; Kasai, Yoshihiro [Department of Electrical and Electronics Engineering, Graduate School of Engineering, Kobe University, Rokkodai 1-1, Nada, Kobe 657-8501 (Japan); Chigi, Yoshitaka; Nishimoto, Tetsuro; Tanaka, Hiroyuki; Kobayashi, Mikihiro [YUMEX INC., Itoda 400, Yumesaki, Himeji, Hyogo, 671-2114 (Japan)

    2008-11-24

    We demonstrated mercury-free narrow-band deep-ultraviolet luminescence from field-emission devices with Al{sub 1-x}Gd{sub x}N thin films. The Al{sub 1-x}Gd{sub x}N thin films were grown on fused silica substrates by a radio frequency reactive magnetron sputtering method. The deposited film shows a strong c-axis preferential orientation. A resolution limited, narrow intra-4f luminescence line from Gd{sup 3+} ions has been observed at 315 nm. The luminescence spectrum depends on the growth temperature of the thin film, and the intensity varies as a function of the GdN mole fraction.

  11. Very narrow band model calculations of atmospheric fluxes and cooling rates

    SciTech Connect

    Bernstein, L.S.; Berk, A.; Acharya, P.K.; Robertson, D.C. [Spectral Sciences, Inc., Burlington, MA (United States)] [and others] [Spectral Sciences, Inc., Burlington, MA (United States); and others

    1996-10-15

    A new very narrow band model (VNBM) approach has been developed and incorporated into the MODTRAN atmospheric transmittance-radiance code. The VNBM includes a computational spectral resolution of 1 cm{sup {minus}1}, a single-line Voigt equivalent width formalism that is based on the Rodgers-Williams approximation and accounts for the finite spectral width of the interval, explicit consideration of line tails, a statistical line overlap correction, a new sublayer integration approach that treats the effect of the sublayer temperature gradient on the path radiance, and the Curtis-Godson (CG) approximation for inhomogeneous paths. A modified procedure for determining the line density parameter 1/d is introduced, which reduces its magnitude. This results in a partial correction of the VNBM tendency to overestimate the interval equivalent widths. The standard two parameter CG approximation is used for H{sub 2}O and CO{sub 2}, while the Goody three parameter CG approximation is used for O{sub 3}. Atmospheric flux and cooling rate predictions using a research version of MODTRAN, MODR, are presented for H{sub 2}O (with and without the continuum), CO{sub 2}, and O{sub 3} for several model atmospheres. The effect of doubling the CO{sub 2} concentration is also considered. These calculations are compared to line-by-line (LBL) model calculations using the AER, GLA, GFDL, and GISS codes. The MODR predictions fall within the spread of the LBL results. The effects of decreasing the band model spectral resolution are illustrated using CO{sub 2} cooling rate and flux calculations. 36 refs., 18 figs., 1 tab.

  12. 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

  13. Narrow-band imaging: a new tool for evaluation of head and neck squamous cell carcinomas. Review of the literature.

    PubMed

    Piazza, C; Dessouky, O; Peretti, G; Cocco, D; De Benedetto, L; Nicolai, P

    2008-04-01

    Head and neck squamous cell carcinoma of the upper aerodigestive tract is well known for its frequently late presentation and diagnosis at an advanced stage. In addition, it is well recognized that it may arise in multiple sites, either synchronously or metachronously. Thus it should be imperative to endoscopically screen the upper aerodigestive tract of patients at risk for head and neck squamous cell carcinoma with a new diagnostic tool, especially due to the fact that early lesions are very difficult to detect even by multiple passes with a standard endoscopy, if they are < or = 1 cm in diameter. Lugol chromoendoscopy, which is mainly used in the oesophagus, is not suitable for the head and neck region due to severe mucosal irritation. Herein, narrow-band imaging is described, a diagnostic tool already proved as a useful screening method in other endoscopic fields, and its application in the early detection of head and neck squamous cell carcinoma is reviewed, as reported by previous studies in the otolaryngologic literature. Narrow-band imaging relies on the principle of depth of penetration of light, with the narrow-band blue light having a short wavelength (415 nm) penetrating into the mucosa and highlighting the superficial vasculature. Furthermore, the blue filter is designed to correspond to the peak absorption spectrum of haemoglobin to enhance the image of capillary vessels on surface mucosa. Thus, superficial mucosal lesions that would be missed by regular white light endoscopy, are identified, in view of their neoangiogenetic pattern of vasculature, using the blue light of the narrow-band imaging. Narrow-band imaging has been used extensively in the lower aerodigestive system, yet there are only 2 reports of applications in the region of the head and neck, specifically the oropharynx and the hypopharynx. However, these are not the only sites that can benefit from narrow-band imaging. Herewith, the uses and importance are highlighted of narrow-band imaging as a future diagnostic tool in otolaryngology, in the pre-, intra- and post-operative settings. PMID:18669067

  14. Narrow-band imaging with magnifying endoscopy for the evaluation of gastrointestinal lesions

    PubMed Central

    Boeriu, Alina; Boeriu, Cristian; Drasovean, Silvia; Pascarenco, Ofelia; Mocan, Simona; Stoian, Mircea; Dobru, Daniela

    2015-01-01

    Narrow band imaging (NBI) endoscopy is an optical image enhancing technology that allows a detailed inspection of vascular and mucosal patterns, providing the ability to predict histology during real-time endoscopy. By combining NBI with magnification endoscopy (NBI-ME), the accurate assessment of lesions in the gastrointestinal tract can be achieved, as well as the early detection of neoplasia by emphasizing neovascularization. Promising results of the method in the diagnosis of premalignant and malignant lesions of gastrointestinal tract have been reported in clinical studies. The usefulness of NBI-ME as an adjunct to endoscopic therapy in clinical practice, the potential to improve diagnostic accuracy, surveillance strategies and cost-saving strategies based on this method are summarized in this review. Various classification systems of mucosal and vascular patterns used to differentiate preneoplastic and neoplastic lesions have been reviewed. We concluded that the clinical applicability of NBI-ME has increased, but standardization of endoscopic criteria and classification systems, validation in randomized multicenter trials and training programs to improve the diagnostic performance are all needed before the widespread acceptance of the method in routine practice. However, published data regarding the usefulness of NBI endoscopy are relevant in order to recommend the method as a reliable tool in diagnostic and therapy, even for less experienced endoscopists. PMID:25685267

  15. Vascular pattern classification of colorectal lesions with narrow band imaging magnifying endoscopy.

    PubMed

    Wada, Yoshiki; Kudo, Shin-ei; Misawa, Masashi; Ikehara, Nobunao; Hamatani, Shigeharu

    2011-05-01

    Magnifying narrow band imaging (NBI) has enabled to observe the vascular pattern of colorectal lesions. Their broad findings have been divided into six groups according to endoscopical vascular features: normal, faint, network, dense, irregular and sparse. Most hyperplastic polyps show a faint pattern. The vascular patterns of adenomas are mainly network or dense ones. The predominant vascular patterns of cancer were irregular and sparse. Indeed, irregular pattern has found to be characteristic for protruded or flat-elevated cancer, whereas sparse pattern unique for depressed cancer. Through NBI, neoplastic lesions could be differentiated from those non-neoplastic with sensitivity of 83.5%, specificity of 98.7% and accuracy of 98.2%. It was able to distinguish between massively submucosal invasive cancers and slightly submucosal invasive cancers by using the vascular pattern with 91.0% sensitivity and 79.4% specificity. The overall accuracy was 88.3%. NBI system has showed to be a valuable technique for distinguishing neoplastic from non-neoplastic lesions, as well as massively from slightly submucosal invasive cancer. Therefore, vascular pattern analysis might be a promising tool for determining treatment selection, whether endoscopical or surgically. PMID:21535214

  16. Effectiveness of narrow-band versus tonal off-frequency maskers.

    PubMed

    Savel, Sophie; Bacon, Sid P

    2003-07-01

    The present study was a follow-up to a pilot study in which it was found that a 500-Hz-wide narrow-band noise (NBN) masker produced more masking than a tonal (T) masker for signal frequencies both above and below the masker frequency. The aim of the present study was to determine to what extent these results were influenced by an interaction of the relatively rapid temporal envelope fluctuations of the NBN and the short (10-ms) duration of the signal. In the first experiment, the masking produced by a regular NBN, a low-noise noise (LNN), and a T was compared. The LNN produced less masking than the NBN, and about as much as the T, suggesting that the inherent amplitude fluctuations in the NBN were largely responsible for the greater masking produced by that masker. In the second experiment, the masking produced by a regular NBN was compared with that by a T for a signal duration of 10 or 200 ms. The difference in masking between the two maskers was reduced or eliminated when the signal duration was 200 ms, because the threshold in the presence of the NBN masker decreased more with increasing signal duration. This could reflect a decreased "confusion" between the signal and the inherent fluctuations of the NBN masker. PMID:12880049

  17. Narrow-band autocorrelation function features for the automatic recognition of acoustic environments.

    PubMed

    Valero, Xavier; Alías, Francesc

    2013-07-01

    Acoustic environments are typically composed of multiple sound sources of different typologies, making them especially complex to model and parameterize. To develop an automatic acoustic environment recognition system, this work proposes a spectro-temporal signal parameterization technique inspired by human perception. The proposed parameters are derived from the analysis of the autocorrelation function of narrow-band signals (NB-ACF) obtained from an auditory gammatone filter bank. Five features related to acoustic phenomena are extracted from the NB-ACF to parameterize sound signals. Experiments are conducted on a 4?h sound database (composed of 15 different acoustic environments) employing four different machine learning techniques: K-nearest neighbor, Gaussian mixture models, neural networks and support vector machines. The averaged recognition rates increase by 4.5% when using the proposed NB-ACF features instead of the popular Mel frequency cepstral coefficients. The improvement is even greater (5.6%) when the features are tested in acoustic environments from unknown locations. These results are attributed to the better modeling of the acoustic environments thanks to the complementarity of the spectro-temporal features derived from NB-ACF analysis. PMID:23862894

  18. Effects of Narrow Band UVB (311 nm) Irradiation on Epidermal Cells

    PubMed Central

    Reich, Adam; M?drek, Karolina

    2013-01-01

    Ultraviolet radiation (UVR) is known to be one of the most important environmental hazards acting on the skin. It was revealed that chronic exposure to UVR accelerates skin aging, induces immunosuppression and may lead to the development of skin cancers. On the other hand, UVR has been shown to be effective in the treatment of numerous skin diseases and thus, various phototherapy modalities have been developed to date. Narrow-band ultraviolet B (NB-UVB) emitting a light with a peak around 311 nm has been demonstrated to be effective in the treatment of various skin disorders; currently it is one of the most commonly used phototherapy devices. Despite NB-UVB has been developed more than 30 years ago, the exact mechanism of its therapeutic action remains poorly understood. To date, most of NB-UVB effects were attributed to its influence on immune cells; however, nearly 90% of NB-UVB irradiation is absorbed by epidermis and keratinocytes seem to be important players in mediating NB-UVB biological activity. Here, we have reviewed the current data about the influence of NB-UVB on epidermal cells, with a special emphasis on cell proliferation and death. PMID:23594996

  19. Narrow-band imaging with magnifying endoscopy for the evaluation of gastrointestinal lesions.

    PubMed

    Boeriu, Alina; Boeriu, Cristian; Drasovean, Silvia; Pascarenco, Ofelia; Mocan, Simona; Stoian, Mircea; Dobru, Daniela

    2015-02-16

    Narrow band imaging (NBI) endoscopy is an optical image enhancing technology that allows a detailed inspection of vascular and mucosal patterns, providing the ability to predict histology during real-time endoscopy. By combining NBI with magnification endoscopy (NBI-ME), the accurate assessment of lesions in the gastrointestinal tract can be achieved, as well as the early detection of neoplasia by emphasizing neovascularization. Promising results of the method in the diagnosis of premalignant and malignant lesions of gastrointestinal tract have been reported in clinical studies. The usefulness of NBI-ME as an adjunct to endoscopic therapy in clinical practice, the potential to improve diagnostic accuracy, surveillance strategies and cost-saving strategies based on this method are summarized in this review. Various classification systems of mucosal and vascular patterns used to differentiate preneoplastic and neoplastic lesions have been reviewed. We concluded that the clinical applicability of NBI-ME has increased, but standardization of endoscopic criteria and classification systems, validation in randomized multicenter trials and training programs to improve the diagnostic performance are all needed before the widespread acceptance of the method in routine practice. However, published data regarding the usefulness of NBI endoscopy are relevant in order to recommend the method as a reliable tool in diagnostic and therapy, even for less experienced endoscopists. PMID:25685267

  20. Characterizing Transiting Extrasolar Planets with Narrow-Band Photometry and GTC/OSIRIS

    E-print Network

    Colon, Knicole D; Lee, Brian; Mahadevan, Suvrath; Blake, Cullen H

    2010-01-01

    We report the first extrasolar planet observations from the 10.4-m Gran Telescopio Canarias (GTC), currently the world's largest, fully steerable, single-aperture optical telescope. We used the OSIRIS tunable filter imager on the GTC to acquire high-precision, narrow-band photometry of the transits of the giant exoplanets, TrES-2b and TrES-3b. We obtained near-simultaneous observations in two near-infrared (NIR) wavebands (790.2 and 794.4 +/- 2.0 nm) specifically chosen to avoid water vapor absorption and skyglow so as to minimize the atmospheric effects that often limit the precision of ground-based photometry. Our results demonstrate a very-high photometric precision with minimal atmospheric contamination despite relatively poor atmospheric conditions and some technical problems with the telescope. We find the photometric precision for the TrES-2 observations to be 0.343 and 0.412 mmag for the 790.2 and 794.4 nm light curves, and the precision of the TrES-3 observations was found to be 0.470 and 0.424 mmag ...

  1. Endoscopic Ex Vivo Evaluation of Bile Concentrations by Narrow Band Imaging: A Pilot Study

    PubMed Central

    Maselli, Roberta; Inoue, Haruhiro; Ikeda, Haruo; Onimaru, Manabu; Yoshida, Akira; Sato, Hiroki; Eleftheriadis, Nikolas

    2015-01-01

    Background. Bile juice plays a major role in duodenogastroesophageal reflux (DGERD). Several devices to directly measure the bile concentration have been proposed. We aimed to ex-vivo evaluate the bile concentration by narrow band imaging (NBI). Method. From six surgical cholecystectomies, the content of the gallbladders was aspirated and the total biliary acid (TBA) concentration was evaluated. 2?mL was employed for serial twofold dilutions. Each dilution was scoped. Images on white light (WL) and NBI were captured and grouped accordingly to NBI-appearance and TBA-concentration. Results. Nondiluted bile had a TBA-concentration of 61965 ± 32989??mol/L. Final dilution (1?:?4096) had 1.16??mol/L. NBI and correspondent WL images were grouped into seven groups, and an NBI/Bile scale was created. Conclusion. The scale showed that not only NBI scale but also white light scale could be useful to predict the bile concentration. This initial study shows that NBI has a potential role in the detection of DGERD and further investigation is warranted to distinguish the presence and the concentration of bile, especially at very low TBA concentrations.

  2. Band gap narrowing of titanium dioxide (TiO2) nanocrystals by electrochemically active biofilms and their visible light activity.

    PubMed

    Kalathil, Shafeer; Khan, Mohammad Mansoob; Ansari, Sajid Ali; Lee, Jintae; Cho, Moo Hwan

    2013-07-21

    We report a simple biogenic-route to narrow the band gap of TiO2 nanocrystals for visible light application by offering a greener method. When an electrochemically active biofilm (EAB) was challenged with a solution of Degussa-TiO2 using sodium acetate as the electron donor, greyish blue-colored TiO2 nanocrystals were obtained. A band gap study showed that the band gap of the modified TiO2 nanocrystals was significantly reduced (E(g) = 2.85 eV) compared to the unmodified white Degussa TiO2 (E(g) = 3.10 eV). PMID:23760526

  3. Fast Time Resolved Spectral Analysis of VLF Banded Emissions

    Microsoft Academic Search

    F. V. Coroniti; R. W. Fredricks; C. F. Kennel; F. L. Scarf

    1971-01-01

    Several classes of VLF banded emissions acquired by the short antenna Ogo 5 electric field detector are investigated by using high time resolution spectral techniques. The fastest temporal resolution of statistically independent spectra is 50 msec; individual spectra are taken every 12.5 msec. VLF banded rising chorus spectra possessed single and\\/or multiple frequency modulated bursts; discrete single modes with unchanging

  4. Satellite Bands in the Emission Spectrum of Cesium

    Microsoft Academic Search

    Joel A. Gwinn; Paul M. Thomas; John F. Kielkopf

    1968-01-01

    Satellite bands near the atomic lines of the emission spectrum of cesium in the presence of heavy noble gases were observed and their positions measured. For the series which also appear in absorption, the measured positions of the band maxima are in general agreement with those previously reported. Several interesting regularities in the data are noted and a simple interpretation

  5. Non-proximity resonant tunneling in multi-core photonic band gap fibers: An efficient mechanism for engineering highly-selective ultra-narrow band pass splitters

    NASA Astrophysics Data System (ADS)

    Florous, Nikolaos J.; Saitoh, Kunimasa; Murao, Tadashi; Koshiba, Masanori; Skorobogatiy, Maksim

    2006-05-01

    The objective of the present investigation is to demonstrate the possibility of designing compact ultra-narrow band-pass filters based on the phenomenon of non-proximity resonant tunneling in multi-core photonic band gap fibers (PBGFs). The proposed PBGF consists of three identical air-cores separated by two defected air-holes which act as highly-selective resonators. With a fine adjustment of the design parameters associated with the resonant-air-holes, phase matching at two distinct wavelengths can be achieved, thus enabling very narrow-band resonant directional coupling between the input and the two output cores. The validation of the proposed design is ensured with an accurate PBGF analysis based on finite element modal and beam propagation algorithms. Typical characteristics of the proposed device over a single polarization are: reasonable short coupling length of 2.7 mm, dual bandpass transmission response at wavelengths of 1.339 and 1.357 ?m, with corresponding full width at half maximum bandwidths of 1.2 nm and 1.1 nm respectively, and a relatively high transmission of 95% at the exact resonance wavelengths. The proposed ultra-narrow band-pass filter can be employed in various applications such as all-fiber bandpass/bandstop filtering and resonant sensors.

  6. Non-proximity resonant tunneling in multi-core photonic band gap fibers: An efficient mechanism for engineering highly-selective ultra-narrow band pass splitters.

    PubMed

    Florous, Nikolaos J; Saitoh, Kunimasa; Murao, Tadashi; Koshiba, Masanori; Skorobogatiy, Maksim

    2006-05-29

    The objective of the present investigation is to demonstrate the possibility of designing compact ultra-narrow band-pass filters based on the phenomenon of non-proximity resonant tunneling in multi-core photonic band gap fibers (PBGFs). The proposed PBGF consists of three identical air-cores separated by two defected air-holes which act as highly-selective resonators. With a fine adjustment of the design parameters associated with the resonant-air-holes, phase matching at two distinct wavelengths can be achieved, thus enabling very narrow-band resonant directional coupling between the input and the two output cores. The validation of the proposed design is ensured with an accurate PBGF analysis based on finite element modal and beam propagation algorithms. Typical characteristics of the proposed device over a single polarization are: reasonable short coupling length of 2.7 mm, dual bandpass transmission response at wavelengths of 1.339 and 1.357 mum, with corresponding full width at half maximum bandwidths of 1.2 nm and 1.1 nm respectively, and a relatively high transmission of 95% at the exact resonance wavelengths. The proposed ultra-narrow band-pass filter can be employed in various applications such as all-fiber bandpass/bandstop filtering and resonant sensors. PMID:19516644

  7. 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.

  8. Superconductivity in narrow-band systems with local nonretarded attractive interactions

    NASA Astrophysics Data System (ADS)

    Micnas, R.; Ranninger, J.; Robaszkiewicz, S.

    1990-01-01

    In narrow-band systems electrons can interact with each other via a short-range nonretarded attractive potential. The origin of such an effective local attraction can be polaronic or it can be due to a coupling between electrons and excitons or plasmons. It can also result from purely chemical (electronic) mechanisms, especially in compounds with elements favoring disproportionation of valent states. These mechanisms are discussed and an exhaustive list of materials in which such local electron pairing occurs is given. The authors review the thermodynamic and electromagnetic properties of such systems in several limiting scenarios: (i) Systems with on-site pairing which can be described by the extended negative-U Hubbard model. The strong-attraction limit of this model, at which it reduces to a system of tightly bound electron pairs (bipolarons) on a lattice, is extensively discussed. These electron pairs behaving as hard-core charged bosons can exhibit a superconducting state analogous to that of superfluid 4He II. The change-over from weak-attraction BCS-like superconductivity to the superfluidity of charged hard-core bosons is examined. (ii) Systems with intersite pairing described by an extended Hubbard model with U>0 and nearest-neighbor attraction and/or nearest-neighbor spin exchange as well as correlated hopping. (iii) A mixture of local pairs and itinerant electrons interacting via a charge-exchange mechanism giving rise to a mutually induced superconductivity in both subsystems. The authors discuss to what extent the picture of local pairing, and in particular superfluidity of hard-core charged bosons on a lattice, can be an explanation for the superconducting and normal-state properties of the high-Tc oxides: doped BaBiO3 and the cuprates.

  9. 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.

  10. Characterizing transiting extrasolar planets with narrow-band photometry and GTC/OSIRIS

    NASA Astrophysics Data System (ADS)

    Colón, Knicole D.; Ford, Eric B.; Lee, Brian; Mahadevan, Suvrath; Blake, Cullen H.

    2010-11-01

    We report the first extrasolar planet observations from the 10.4-m Gran Telescopio Canarias (GTC), currently the world's largest, fully steerable, single-aperture optical telescope. We used the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) tunable filter imager on the GTC to acquire high-precision, narrow-band photometry of the transits of the giant exoplanets, TrES-2b and TrES-3b. We obtained near-simultaneous observations in two near-infrared wavebands (790.2 and 794.4 +/- 2.0 nm) specifically chosen to avoid water vapour absorption and skyglow so as to minimize the atmospheric effects that often limit the precision of ground-based photometry. Our results demonstrate a very-high photometric precision with minimal atmospheric contamination despite relatively poor atmospheric conditions and some technical problems with the telescope. We find the photometric precision for the TrES-2 observations to be 0.343 and 0.412 mmag for the 790.2- and 794.4-nm light curves, and the precision of the TrES-3 observations was found to be 0.470 and 0.424 mmag for the 790.2- and 794.4-nm light curves, respectively. We also discuss how future follow-up observations of transiting planets with this novel technique can contribute to the characterization of Neptune- and super-Earth-size planets to be discovered by space-based missions like CoRoT and Kepler, as well as measure atmospheric properties of giant planets, such as the strength of atmospheric absorption features.

  11. Usefulness of magnifying narrow-band imaging endoscopy for the diagnosis of gastric and colorectal lesions.

    PubMed

    Hirata, Ichiro; Nakagawa, Yoshihito; Ohkubo, Masaaki; Yahagi, Naohisa; Yao, Kenshi

    2012-01-01

    A series of studies about the potential usefulness of magnifying endoscopy with narrow-band imaging (NBI) for the diagnosis of gastric and colonic lesion is reviewed. Concerning the magnifying NBI appearances of gastric lesions, a light blue crest is a highly accurate sign of the presence of histological intestinal metaplasia. Also, the degree of irregularity of the mucosal and vascular pattern is correlated with the histological severity of Helicobacter pylori-associated chronic gastritis. According to the 'VS classification', an irregular microvascular pattern and/or an irregular microsurface pattern together with a clear demarcation line are characteristic for early gastric carcinoma, and a multicenter prospective randomized controlled trial demonstrated that magnifying endoscopy with NBI is superior to ordinary white light endoscopy for making a differential diagnosis of a small depressed lesion between carcinoma and non-carcinoma. Concerning the magnifying NBI appearances of colonic tumor, the vague or invisible microvascular pattern is mostly observed in hyperplastic polyp. The regular meshed microvascular pattern is mostly observed in adenoma. The irregular meshed microvascular pattern is mostly observed in intramucosal or shallow submucosal-invasive carcinoma. The decreased or loose microvasucular pattern is mostly observed in deep submucosal-invasive carcinoma. Thus, magnifying NBI endoscopy is useful for the differentiation of colorectal non-adenomatous lesions from adenoma, the differentiation of adenoma from carcinoma, and the assessment of invasion depth of early colorectal carcinoma. At present, several magnifying NBI classifications for the diagnosis of early colorectal neoplasia have been proposed in Japan. Recently, the NICE classification based on NBI findings with/without magnification for colorectal tumor was established by an international group. PMID:22269282

  12. 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

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

    SciTech Connect

    Wang, Wen-Hung [Department of Otolaryngology, Chang Gung Memorial Hospital at Chiayi and Chang Gung University College of Medicine, Taiwan (China); Lin, Yen-Chun, E-mail: sarah_travel@hotmail.com [Department of Otolaryngology, Chang Gung Memorial Hospital at Chiayi and Chang Gung University College of Medicine, Taiwan (China); Chen, Wen-Cheng; Chen, Miao-Fen [Department of Radiation Oncology, Chang Gung Memorial Hospital at Chiayi and Chang Gung University College of Medicine, Taiwan (China); Chen, Chih-Cheng [Department of Hematology and Oncology, Chang Gung Memorial Hospital at Chiayi and Chang Gung University College of Medicine, Taiwan (China); Lee, Kam-Fai [Department of Pathology, Chang Gung Memorial Hospital at Chiayi and Chang Gung University College of Medicine, Taiwan (China)

    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.

  14. Enhanced narrow-bandwidth emission during high-order harmonic generation from aligned molecules.

    PubMed

    Zhang, Chaojin; Yao, Jinping; Umran, Fadhil A; Ni, Jielei; Zeng, Bin; Li, Guihua; Lin, Di

    2013-02-11

    We theoretically investigate the selective enhancement of high-harmonic generation (HHG) in a small spectral range when an orthogonal-polarized two-color laser field interacts with aligned O(2) molecules. It is shown clearly that the enhanced narrow-bandwidth emission near the cutoff of the HHG spectrum can be effectively controlled by the molecular alignment angle, laser intensity and the relative phase of two-color laser fields. Furthermore, the strong dependence of narrow-bandwidth HHG on molecular alignment angle indicates that it encodes information about O(2) molecular orbitals, so it may be an alternative method for reconstruction of O(2) molecular orbitals. PMID:23481785

  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. 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.

  17. 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.

  18. 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

  19. The role of narrow-band imaging in the management of non-muscle-invasive bladder cancer.

    PubMed

    Naselli, Angelo; Hurle, Rodolfo; Puppo, Paolo

    2012-12-01

    Narrow-band imaging is a young optical enhancement technology for endoscopy. It is a filter to the standard white light which increases the contrast between underlying vasculature and epithelial strata of the mucosa, improving the detection of bladder cancer with particular regard to high grade, flat lesions. Narrow band imaging is absolutely safe, may be used any time during a procedure, either during office cystosopy or transurethral resection, and implies a minimal burden for the healthcare provider given the absence of a learning curve and the limited cost of the camera and light source. The ameliorated detection translates into an improved management of the disease and a lower recurrence risk in prospective randomized studies, suggesting the inclusion of the technology in daily clinical practice. PMID:23253218

  20. Narrow-Band Survey of the GOODS Fields: Search for Lyman-Alpha Emitters at z = 5.7

    E-print Network

    Masaru Ajiki; Bahram Mobasher; Yoshiaki Taniguchi; Yasuhiro Shioya; Tohru Nagao; Takashi Murayama; Shunji S. Sasaki

    2005-10-24

    We present results from optical narrow-band lambda_c = 8150A ~ and Delta lambda = 120A) observations of the Great Observatories Origins Deep Survey (GOODS) fields, using Suprime-Cam on the Subaru Telescope. Using these narrow-band data, we then perform a survey of Lyman alpha Emitters (LAEs) at z~5.7. The LAE survey covers an area of approx 320 arcmin^2 and a co-moving volume of ~8.0 x 10^4 Mpc^3. We found a total of 10 (GOODS-N) and 4 (GOODS-S) LAE candidates at z~5.7. We perform a study of the spatial distribution, space density, and star formation properties of the LAEs at z~5.7.

  1. A compact, narrow-band, and low-noise 800-mW laser source at 980 nm

    NASA Astrophysics Data System (ADS)

    Pliska, Tomas; Matuschek, Nicolai; Troger, Joerg; Schmidt, Berthold; Mohrdiek, Stefan; Harder, Christoph

    2005-04-01

    We report on the development of a new cost-effective, small form-factor laser source at a wavelength of 980 nm. The laser module is based on proven technology commonly used for pump laser modules deployed in fiber amplifiers of telecommunication networks. The package uses a state-of-the-art 14-pin butterfly housing with a footprint of 30x15 mm2 with a Fabry-Perot AlGaAs-InGaAs pump laser diode mounted inside having an anti-reflection coating on its front facet. The light is coupled into a single-mode polarization-maintaining fiber with a mode-field diameter of 6.6 micrometer. The spectral properties of the source are defined by a fiber Bragg grating (FBG) that provides feedback in a narrow reflection band. The laser back facet and the FBG form a long resonant cavity of 1.7 m length in which laser light with a low coherence length of a few cm is generated. This configuration with the laser being operated in the coherence-collapse regime has the advantage of being robust against variations in the optical path, thus enabling stable and mode-hop free emission. The laser module has the following properties: a continuous-wave fiber output power exceeding 800 mW, a spectral bandwidth of less than 50 pm, a root-mean square power variation of less than 0.2 % from DC to 2 MHz over the entire power operating range, and a polarization extinction ratio of more than 20 dB. This is a compact, low noise, high power source for frequency conversion with nonlinear optical materials, such as blue light generation.

  2. Performance comparison of a slotted ALOHA DS\\/SSMA network and a multichannel narrow-band slotted ALOHA network

    Microsoft Academic Search

    Peter W. de Graaf; James S. Lehnert

    1998-01-01

    Throughput, delay, and stability for two slotted ALOHA packet radio systems are compared. One system is a slotted direct-sequence spread-spectrum multiple-access (DS\\/SSMA) network where each user employs a newly chosen random signature sequence for each bit in a transmitted packet. The other system is a multiple-channel slotted narrow-band ALOHA network where each packet is transmitted over a randomly selected channel.

  3. Susceptibility of Microcontroller Devices due to Coupling Effects Under Narrow-Band High Power Electromagnetic Waves by Magnetron

    Microsoft Academic Search

    J. I. Hong; S. M. Hwang; C. S. Huh

    2008-01-01

    We investigated the malfunction and destruction characteristics of microcontroller devices under narrow-band high power electromagnetic (NB-HPEM) wave by magnetron. NB-HPEM wave was rated at a microwave output of 0 to 1000 W at a frequency of 2460 ± 50 MHz, and was radiated from an open-ended standard rectangular waveguide (WR-340) to free space. The influence of different reset, clock, data,

  4. Underwater audiogram of a Pacific walrus (Odobenus rosmarus divergens) measured with narrow-band frequency-modulated signals

    Microsoft Academic Search

    R. A. Kastelein; P. Mosterd; B. van Santen; M. Hagedoorn; D. de Haan

    2002-01-01

    The underwater hearing sensitivity of an 18-year-old male Pacific walrus was measured in a pool by using a go\\/no-go response paradigm and the up-down staircase method. Auditory sensitivity was measured using narrow-band, frequency-modulated signals (1500 ms duration) with center frequencies ranging from 0.125 to 15 kHz. The resulting underwater audiogram (50 The range of best hearing (10 dB from the

  5. 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.

  6. 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

  7. A Novel Technique for Narrow-Band Tunable Filter Photometry to Enable Ground-Based Detection of Earth-Sized Exoplanets

    NASA Astrophysics Data System (ADS)

    Kimock, Benjamin; Colón, Knicole; Pepper, Joshua

    2015-01-01

    We present a novel technique for the removal of sky rings from narrow-band photometry, which arise due to atmospheric OH emission. Our goal is to achieve very high-precision ground-based photometry to enable detection of small transit or occultation signals from exoplanets. We demonstrate our technique on narrow-band photometry of the super-Earth-size transiting planet CoRoT-7b acquired with the OSIRIS tunable filter imager on the 10.4-meter Gran Telescopio Canarias. Without removing sky rings, we do not detect a transit of CoRoT-7b at any significance, but after removing sky rings with our technique, we detect a transit at a significance of 3.2-sigma. Our detection of the transit suggests that this technique can enable ground-based detection of exoplanets with transit or occultation depths on the order of 0.1 mmag. At the time of writing, we believe this to be the first ground-based detection of a transit of a super-Earth orbiting a Sun-like star. This implies that the characterization of Earth-sized planets discovered by space-based missions like Kepler and the future TESS mission may be possible from the ground.

  8. SMOS REFLEX 2003: L-band emissivity characterization of vineyards

    Microsoft Academic Search

    M. Vall-Llossera; A. Camps; I. Corbella; F. Torres; N. Duffo; A. Monerris; R. Sabia; D. Selva; C. Antolin; E. Lopez-Baeza; J. F. Ferrer; K. Saleh

    2005-01-01

    The goal of the Soil Moisture and Ocean Salinity mission over land is to infer surface soil moisture from multiangular L-band radiometric measurements. As the canopy affects the microwave emission of land, it is necessary to characterize different vegetation layers. This paper presents the Reference Pixel L-Band Experiment (REFLEX), carried out in June-July 2003 at the Vale`ncia Anchor Station, Spain,

  9. Coherent control of spontaneous emission near a photonic band edge

    Microsoft Academic Search

    Mesfin Woldeyohannes; Sajeev John

    2003-01-01

    We demonstrate the coherent control of spontaneous emission for a three-level atom located within a photonic band gap (PBG) material, with one resonant frequency near the edge of the PBG. Spontaneous emission fro mt he three-level atom can be totally suppressed or strongly enhanced depending on the relative phase between the steady-state control laser coupling the two upper levels and

  10. Tunable Subluminal Propagation of Narrow-band X-Ray Pulses.

    PubMed

    Heeg, Kilian P; Haber, Johann; Schumacher, Daniel; Bocklage, Lars; Wille, Hans-Christian; Schulze, Kai S; Loetzsch, Robert; Uschmann, Ingo; Paulus, Gerhard G; Rüffer, Rudolf; Röhlsberger, Ralf; Evers, Jörg

    2015-05-22

    Group velocity control is demonstrated for x-ray photons of 14.4 keV energy via a direct measurement of the temporal delay imposed on spectrally narrow x-ray pulses. Subluminal light propagation is achieved by inducing a steep positive linear dispersion in the optical response of ^{57}Fe Mössbauer nuclei embedded in a thin film planar x-ray cavity. The direct detection of the temporal pulse delay is enabled by generating frequency-tunable spectrally narrow x-ray pulses from broadband pulsed synchrotron radiation. Our theoretical model is in good agreement with the experimental data. PMID:26047228

  11. Tunable Subluminal Propagation of Narrow-band X-Ray Pulses

    NASA Astrophysics Data System (ADS)

    Heeg, Kilian P.; Haber, Johann; Schumacher, Daniel; Bocklage, Lars; Wille, Hans-Christian; Schulze, Kai S.; Loetzsch, Robert; Uschmann, Ingo; Paulus, Gerhard G.; Rüffer, Rudolf; Röhlsberger, Ralf; Evers, Jörg

    2015-05-01

    Group velocity control is demonstrated for x-ray photons of 14.4 keV energy via a direct measurement of the temporal delay imposed on spectrally narrow x-ray pulses. Subluminal light propagation is achieved by inducing a steep positive linear dispersion in the optical response of 57Fe Mössbauer nuclei embedded in a thin film planar x-ray cavity. The direct detection of the temporal pulse delay is enabled by generating frequency-tunable spectrally narrow x-ray pulses from broadband pulsed synchrotron radiation. Our theoretical model is in good agreement with the experimental data.

  12. Narrow-band holographic optical filter using thick efficient holographic gratings

    Microsoft Academic Search

    Richard I. Billmers; Elizabeth J. Billmers; Ryszard Burzynski; John F. Weibel; L. H. Heverley; Martin K. Casstevens; Thomas P. Curran; V. Michael Contarino

    2002-01-01

    RL Associates in conjunction with Hybrid Technologies is developing a narrow linewidth optical filter employing extremely thick volume holographic diffraction gratings. The gratings are written in MEMPLEX, a new holographic materia invented by Laser Photonics Technology, Inc. and licensed to Hybrid Technologies. MEMPLEX has the following characteristics: (1) Excellent optical clarity, (2) Preparable at any thickness up to 10 mm,

  13. MEASUREMENT AND ANALYSIS OF NARROW-BAND SURFACE ACOUSTIC WAVES IN CERAMIC ENVIRONMENTAL BARRIER

    E-print Network

    properties and thickness of mullite environmental barrier coatings deposited on SiC substrates. Narrow) is a promising environmental barrier coating for silicon based ceramics, such as SiC and Si3N4, because of its-sectional image of a graded mullite coating grown on a SiC substrate using CVD and captured using an optical

  14. Locally Optimally-emitting Clouds and the Narrow Emission Lines in Seyfert Galaxies

    E-print Network

    Jason W. Ferguson; Kirk T. Korista; Jack A. Baldwin; Gary J. Ferland

    1997-05-12

    The narrow emission line spectra of active galactic nuclei are not accurately described by simple photoionization models of single clouds. Recent Hubble Space Telescope images of Seyfert 2 galaxies show that these objects are rich with ionization cones, knots, filaments, and strands of ionized gas. Here we extend to the narrow line region the ``locally optimally emitting cloud'' (LOC) model, in which the observed spectra are predominantly determined by powerful selection effects. We present a large grid of photoionization models covering a wide range of physical conditions and show the optimal conditions for producing many of the strongest emission lines. We show that the integrated narrow line spectrum can be predicted by an integration of an ensemble of clouds, and we present these results in the form of diagnostic line ratio diagrams making comparisons with observations. We also predict key diagnostic line ratios as a function of distance from the ionizing source, and compare these to observations. The predicted radial dependence of the [O III]/[O II] ratio may be matched to the observed one in NGC4151, if the narrow line clouds see a more intense continuum than we see. The LOC scenario when coupled with a simple Keplerian gravitational velocity field will quite naturally predict the observed line width versus critical density relationship. The influence of dust within the ionized portion of the clouds is discussed and we show that the more neutral gas is likely to be dusty, although a high ionization dust-free region is most likely present too. This argues for a variety of NLR cloud origins.

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

    Microsoft Academic Search

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

    2006-01-01

    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

  16. A Mild Case of Adult-Onset Keratosis Lichenoides Chronica Successfully Treated with Narrow-Band UVB Monotherapy

    PubMed Central

    Nomura, Takashi; Toichi, Eiko; Miyachi, Yoshiki; Kabashima, Kenji

    2012-01-01

    Keratosis lichenoides chronica (KLC) is a rare keratotic disorder of unknown origin. Effective treatment has not been established yet. Here, we present adult-onset KLC, which was treated by narrow-band ultraviolet B (NB-UVB) monotherapy. Although NB-UVB was reported to be effective for pediatric-onset KLC, it has not been clear if this regimen is also useful for adult-onset type because pediatric-onset KLC is suggested to be different in nature. We assume that KLC is treatable by NB-UVB regardless of the age of the patient. PMID:23185159

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

    SciTech Connect

    Paley, J.; Djurcic, Z.; /Argonne; Harris, D.; Tesarek, R.; /Fermilab; Feldman, G.; /Harvard U.; 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.

  18. Generation of narrow-band ultrasound with a long cavity mode-locked Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Deaton, J. B., Jr.; McKie, A. D. W.; Spicer, J. B.; Wagner, J. W.

    1990-06-01

    A passively mode-locked, flashlamp-pumped Nd:YAG laser with a cavity length of 11.19 m has been developed to study the noncontact generation of narrow-band ultrasound. The individual mode-locked pulses acted as separate sources of ultrasound, producing a train of acoustic pulses with a repetition rate of about 13.4 MHz. The ultrasound was generated in an aluminum sample and remotely detected with a path stabilized Michelson interferometer. The energy in the multiple pulse acoustic signal was confined to a considerably reduced spectral range compared with that in a single pulse.

  19. An asymmetric quantum well infrared photodetector with voltage-tunable narrow and broad-band response

    Microsoft Academic Search

    L. C. Lenchyshyn; H. C. Liu; M. Buchanan; Z. R. Wasilewski

    1996-01-01

    We describe a 9 ?m AlGaAs\\/GaAs asymmetric quantum well infrared photodetector with voltage tunable spectral bandwidth. A very narrow spectral response of 9.2 meV (0.6 ?m) full width half maximum is observed for an applied electric field of 28 kV\\/cm. The linewidth quadruples when the bias polarity is reversed, with very little shift in the peak detection wavelength. This structure

  20. Development of a narrow-band, tunable, frequency-quadrupled diode laser for UV absorption spectroscopy

    Microsoft Academic Search

    Jeffrey P. Koplow; Dahv A. V. Kliner; Lew Goldberg

    1998-01-01

    A compact, lightweight, low-power-consumption source of tunable, narrow-bandwidth blue and UV radiation is described. In this source, a single-longitudinal-mode diode laser seeds a pulsed, GaAlAs tapered amplifier whose 860-nm output is frequency quadrupled by two stages of single-pass frequency doubling. Performance of the laser system is characterized over a wide range of amplifier duty cycles (0.1 1.0), pulse durations (50

  1. Narrow 0+ state in 20Ne and the 06+ and 07+ rotational bands

    Microsoft Academic Search

    H. T. Richards; G. Caskey; J. H. Billen; S. R. Riedhauser; D. J. Steck

    1984-01-01

    A reanalysis of old data removes the (0+,2+) ambiguity for a very narrow state at Ex(20Ne)=11.55 MeV and gives a unique 0+ assignment. Such a 0+ state corresponds well to a predicted state at 11.494 MeV of unusually small reduced widths for decay to both the ground and first excited state of 16O. This new 0+ state is a better

  2. Increased conductivities of Cr doped Al2-xCrxO3 powders due to band gap narrowing

    NASA Astrophysics Data System (ADS)

    Badar, Nurhanna; Kamarulzaman, Norlida; Rusdi, Roshidah; Abdul Aziz, Nor Diyana; Kun Fun, Hoong

    2014-03-01

    A high Cr content in the synthesized Al2-xCrxO3 materials was achieved via a new synthesis route, the self propagating combustion method, for investigation of the effect of Cr substitution on the electrical, optical band gap and structural characteristics of the modified Al2O3 materials. X-ray diffraction (XRD) results showed that all the samples were pure and that Cr was successfully substituted in the crystal lattice. The cell parameters and volume are linearly dependent on the Cr content. AC impedance spectroscopy results show that conductivity of the Cr doped samples increases exponentially with Cr content. This is attributed to band gap narrowing of the Al2-xCrxO3 powders as obtained from UV-visible spectrophotometric studies.

  3. 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.

  4. Magnetism switching and band-gap narrowing in Ni-doped PbTiO3 thin films

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Ions doping-driven structural phase transition accompanied by magnetism switching and band-gap narrowing effects has been observed in PbTi1-xNixO3-? (xPTNO, x = 0.00, 0.06, and 0.33) thin films. With the increase of x, the xPTNO thin films exhibit not only a phase transition from the pseudotetragonal structure to a centrosymmetric cubic structure but also a drastic decrease of grain size. Moreover, the as-grown Ni-doped PbTiO3 (PTO) thin films show obvious room-temperature ferromagnetism and an increased saturation magnetization with increasing the Ni content, in contrast to undoped PTO, which shows diamagnetism. A bound magnetic polaron model was proposed to understand the observed ferromagnetic behavior of PTO-derived perovskite thin films. Furthermore, the 0.33PTNO thin film presents a narrowed band-gap, much smaller than that of PTO, which is attributed 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. These findings may open up a route to explore promising perovskite oxides as candidate materials for use in multiferroics and solar-energy devices.

  5. The contribution of interaural intensity differences to the horizontal auditory localization of narrow bands of noise

    Microsoft Academic Search

    Matthew H. Bakke

    1999-01-01

    Brief bursts of third-octave bands of noise (center frequencies at 0.5, 1.0, 2.0 and 4.0 kHz) and band pass noises with different degrees of low-frequency content (0.5 to 4.0 kHz, 1.0 to 4.0 kHz and 2.0 to 4.0 kHz) were recorded binaurally from 17 different horizontal locations (90 degrees on the left to 90 degrees on the right in 11.25

  6. Optimal processing of an impulse radio signal subjected to narrow band interference

    Microsoft Academic Search

    Reza Pasand; S. Khalesehosseini; J. Nielsen

    2005-01-01

    Ultra wide band (UWB) links are inherently subject to narrowband interference (NBI) from other narrowband communication links. An UWB receiver architecture that is proven effective in mitigating NBI sources is the analog filter bank (AFB) followed by a generalized matched filter (GMF) processing as introduced in J. Nielsen et al. (2004) and R. Pasand et al. (2004). In this paper,

  7. High-power, diffraction-limited, narrow-band, external-cavity diode laser

    Microsoft Academic Search

    W. F. Sharfin; J. Seppala; A. Mooradian; B. A. Soltz; R. G. Waters; B. J. Vollmer; K. J. Bystrom

    1989-01-01

    We demonstrate an external-cavity GaAs\\/GaAlAs single quantum well diode laser that produces 1.6 W of cw power with 32% overall efficiency in a spectral band of 0.02 nm. Over 0.1 W is measured in a single-frequency, diffraction-limited beam.

  8. High-power, diffraction-limited, narrow-band, external-cavity diode laser

    Microsoft Academic Search

    W. F. Sharfin; J. P. Seppala; A. Mooradian; B. A. Soltz; R. G. Waters; B. J. Vollmer; K. J. Bystrom

    1989-01-01

    An external-cavity GaAs\\/GaAlAs single quantum well diode laser is demonstrated that produces 1.6 W of CW power with 32 percent overall efficiency in a spectral band of 0.02 nm. Over 0.1 W is measured in a single-frequency, diffraction-limited beam.

  9. Emission from CO band heads in young stellar objects

    NASA Astrophysics Data System (ADS)

    Geballe, T. R.; Persson, S. E.

    1987-01-01

    Line emission from carbon monoxide at the positions of the delta-v = 2 band heads has been detected in three young stellar objects (S106 IR, NGC 2024/IRs 2, GL 2789) and in MWC 349 out of 16 objects in which it has been searched for. Previously band head emission had been reported among young stellar objects only in the Becklin-Neugebauer object and the Rho Ophiucus source, WL 16. The excitation mechanisms for the CO in the new objects appears to be the same as that deduced by Scoville et al. (1979, 1983) for BN, i.e., collisions within a dense, hot, and compact region near the star. In at least some of the objects this region is probably a circumstellar disk.

  10. 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.

  11. The Largest Blueshifts of [O III] emission line in Two Narrow-Line Quasars

    E-print Network

    Kentaro Aoki; Toshihiro Kawaguchi; Kouji Ohta

    2004-09-22

    We have obtained optical intermediate resolution spectra (R = 3000) of the narrow-line quasars DMS 0059-0055 and PG 1543+489. The [O III] emission line in DMS 0059-0055 is blueshifted by 880 km/s relative to Hbeta. We also confirm that the [O III] emission line in PG 1543+489 has a relative blueshift of 1150 km/s. These two narrow-line quasars show the largest [O III] blueshifts known to date among type 1 active galactic nuclei (AGNs). The [O III] emission lines in both objects are broad (1000 - 2000 km/s) and those in DMS 0059-0055 show strong blue asymmetry. We interpret the large blueshift and the profile of the [O III] lines as the result of an outflow interacting with circumnuclear gas. Among type 1 AGNs with large blueshifted [O III], there is no correlation between the Eddington ratios and the amount of [O III] blueshifts. Combining our new data with published results, we confirm that the Eddington ratios of the such AGNs are the highest among AGNs with the same black hole masses. These facts suggest that the Eddington ratio is a necessary condition or the [O III] blueshifts weakly depend on the Eddington ratio. Our new sample suggests that there are possible necessary conditions to produce an outflow besides a high Eddington ratio: large black hole mass (> 10^7 M_solar) or high mass accretion rate (> 2 M_solar/yr) or large luminosity (lambda L_{lambda} (5100A) > 10^44.6 erg/s).

  12. Emergent dimensional reduction of the spin sector in a model for narrow-band manganites

    SciTech Connect

    Liang, Shuhua [ORNL; Daghofer, Maria [ORNL; Dong, Shuai [Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing; Sen, Cengiz [ORNL; Dagotto, Elbio R [ORNL

    2011-01-01

    The widely used double-exchange model for manganites is shown to support various striped phases at filling fractions 1/n (n = 3, 4, 5, . . .), in the previously unexplored regime of narrow bandwidth and small Jahn-Teller coupling. Working in two dimensions, our main result is that these stripes can be individually spin flipped without a physically relevant change in the energy, i.e., we find a large ground-state manifold with nearly degenerate energies. The two-dimensional spin system thus displays an unexpected dynamically generated dimensional reduction into decoupled one-dimensional stripes, even though the electronic states remain two dimensional. Relations of our results with recent literature addressing compass models in quantum computing are discussed.

  13. Faint Object Spectrograph Spectra of the UV Emission Lines in NGC 5558: Detection of Strong Narrow Components

    NASA Technical Reports Server (NTRS)

    Crenshaw, D. Michael; Boggess, Albert; Wu, Chi-Chao

    1993-01-01

    Ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 were obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope on 1992 July 5, when the UV continuum and broad emission lines were at their lowest ever observed level. The high resolution of the spectra, relative to previous UV observations, and the low state of NGC 5548 allow the detection and accurate measurement of strong narrow components of the emission lines of Ly alpha, C IV 1549, and C III 1909. Isolation of the UV narrow components enables a detailed comparison of narrow-line region (NLR) properties in Seyfert 1 and 2 galaxies, and removal of their contribution is important for studies of the broad-line region (BLR). Relative to the other narrow lines, C IV 1549 is much stronger in NGC 5548 than in Seyfert 2 galaxies, and Mg II 2798 is very weak or absent.

  14. Effects of laser source parameters on the generation of narrow band and directed laser ultrasound

    NASA Technical Reports Server (NTRS)

    Spicer, James B.; Deaton, John B., Jr.; Wagner, James W.

    1992-01-01

    Predictive and prescriptive modeling of laser arrays is performed to demonstrate the effects of the extension of array elements on laser array performance. For a repetitively pulsed laser source (the temporal laser array), efficient frequency compression is best achieved by detecting longitudinal waves off-epicenter in plates where the source size and shape directly influence the longitudinal wave shape and duration; the longitudinal array may be tailored for a given repetition frequency to yield efficient overtone energy compression into the fundamental frequency band. For phased arrays, apparent array directivity is heavily influenced by array element size.

  15. Anatomy of the AGN in NGC 5548: the X-ray narrow emission lines

    NASA Astrophysics Data System (ADS)

    Whewell, M.; Branduardi-Raymont, G.; Kaastra, J.; Mehdipour, M.; Bianchi, S.; NGC 5548 Collaboration

    2014-07-01

    After a very successful multi-satellite campaign on Mrk 509 in 2009, we conducted a similar campaign on the AGN NGC 5548 in 2013. During the latter the source appeared unusually strongly absorbed in the soft X-rays, and signatures of strong outflows were also present in the UV. While a talk giving an overview of the campaign (PI: J. Kaastra) is also proposed at this conference, we will focus here on the data obtained from the XMM-RGS, resulting in a stacked spectrum of 660 ks. Narrow emission lines, including He-like triplets of Oxygen, Nitrogen and Neon, and radiative recombination (RRC) features dominate this spectrum due to the low soft X-ray continuum flux. All emission features are consistent with having constant flux over our campaign. The O VII triplet has been one focus of our analysis, especially due to unexpected differences of ˜300 km s^{-1} among the measured outflow velocities of its individual lines. The RRCs allow us to directly calculate a temperature of the emitting gas of a few eV (˜10^{4}K), favouring photoionised conditions. We have modelled the emission lines and features using the photoionisation code Cloudy, to attempt to construct a self-consistent picture of the physical environment of the AGN.

  16. External-cavity-controlled 32MHz narrow-band CW GaAlAs-diode lasers

    Microsoft Academic Search

    C. Voumard

    1977-01-01

    By coupling a CW GaAlAs-diode laser to an external resonator with Fabry-Perot etalons as dispersive elements, emission was reduced to a single-axial mode of 32-MHz width. The wavelength could be coarsely tuned over a spectral range of over 10 nm. Fine tuning over about 500 MHz was achieved by varying the external cavity length by less than one third the

  17. The effect of narrow-band noise maskers on increment detection1

    PubMed Central

    Messersmith, Jessica J.; Patra, Harisadhan; Jesteadt, Walt

    2010-01-01

    It is often assumed that listeners detect an increment in the intensity of a pure tone by detecting an increase in the energy falling within the critical band centered on the signal frequency. A noise masker can be used to limit the use of signal energy falling outside of the critical band, but facets of the noise may impact increment detection beyond this intended purpose. The current study evaluated the impact of envelope fluctuation in a noise masker on thresholds for detection of an increment. Thresholds were obtained for detection of an increment in the intensity of a 0.25- or 4-kHz pedestal in quiet and in the presence of noise of varying bandwidth. Results indicate that thresholds for detection of an increment in the intensity of a pure tone increase with increasing bandwidth for an on-frequency noise masker, but are unchanged by an off-frequency noise masker. Neither a model that includes a modulation-filter-bank analysis of envelope modulation nor a model based on discrimination of spectral patterns can account for all aspects of the observed data. PMID:21110593

  18. On the X-ray Baldwin effect for narrow Fe Kalpha emission line

    E-print Network

    P. Jiang; J. X. Wang; T. G. Wang

    2006-03-14

    Most Active Galactic Nuclei (AGN) exhibit a narrow Fe Kalpha line at ~ 6.4 keV in the X-ray spectra, due to the fluorescent emission from cold material far from the inner accretion disk. Using XMM-Newton observations, Page et al. found that the equivalent width (EW) of the narrow Fe Kalpha line decreases with increasing luminosity (EW ~ L^-0.17pm0.08), suggesting a decrease in the covering factor of the material emitting the line (presumably the torus). By combining the archival Chandra HETG observations of 34 type 1 AGNs with XMM observations in literature, we build a much large sample with 101 AGNs. We find a similar X-ray Baldwin effect in the sample (EW ~ L^-0.2015pm0.0426), however, we note that the anti-correlation is dominated by the radio loud AGN in the sample, whose X-ray spectra might be contaminated by the relativistic jet. Excluding the radio loud AGN, we find a much weaker anti-correlation (EW ~ L^-0.1019pm0.0524). We present Monte-Carlo simulations showing that such a weak anti-correlation can be attributed to the relative short time scale variations of the X-ray continuum.

  19. Doppler sidebands in the cross-spectral density of narrow-band reverberation from a dynamic sea surface.

    PubMed

    Gragg, Robert F

    2003-09-01

    Analytic methods are used to formulate the impact of a random dynamic sea surface on the space-frequency characteristics of bistatic reverberation. A narrow-band point source is positioned beneath the time-dependent surface of a range-independent ocean. The small-waveheight perturbative approximation is invoked, and attention is focused on the Doppler sideband contributions to the reverberation cross-spectral density for an arbitrarily placed receiver pair. The new expression that results is identified as an active scattering generalization of the van Cittert-Zernike theorem from classical partial coherence theory. This work is the first to explicitly predict the sideband structure in the cross-spectral density of the field scattered from a realistic moving sea surface. A numerical example is presented for a shallow source and shallow receivers in a homogeneous ocean. PMID:14514191

  20. Clinical usefulness of narrow band imaging magnifying classification for colorectal tumors based on both surface pattern and microvessel features.

    PubMed

    Oka, Shiro; Tanaka, Shinji; Takata, Sayaka; Kanao, Hiroyuki; Chayama, Kazuaki

    2011-05-01

    We use the narrow band imaging (NBI) magnifying classification (Hiroshima Classification) on the basis of both their surface pattern and microvascular architecture to characterize colorectal tumors. Herein, we describe the Hiroshima Classification in detail and provide statistical data supporting its usefulness in diagnosing histologic type, whether a hyperplastic lesion, tubular adenoma, carcinoma with intramucosal to submucosal scanty invasion or carcinoma with submucosal massive invasion, and thus in selecting the appropriate treatment strategy. We also discuss the circumstances in which the Hiroshima Classification must be augmented by conventional pit pattern diagnosis. NBI magnification is easily carried out. We strongly recommend application of NBI magnification to the differential diagnosis of colorectal lesions as well as treatment decision making. PMID:21535213

  1. 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.

  2. Correlation effects in photoemission from adsorbates: Hydrogen on narrow-band metals

    NASA Astrophysics Data System (ADS)

    Rubio, J.; Refolio, M. C.; López Sancho, M. P.; López Sancho, J. M.

    1988-08-01

    This paper deals with photoemission from a one-level atom adsorbed on a metal surface within the context of Anderson's Hamiltonian. The occupied part of the adsorbate density of states (DOS) is calculated by means of a many-electron approach that incorporates the following ingredients: (1) A neat separation between final-state interactions and initial (ground-state) effects. (2) The method (a Lehmann-type representation) leans heavily on the resolvent operator, R(z)=(z-H)-1, which is obtained by expressing Dyson's equation in terms of the (N-1)-electron states (configurations) that diagonalize the hopping-free part of Anderson's Hamiltonian, thereby including the atomic correlation (U) in a nonperturbative way while expanding in powers of the hopping parameter (V). (3) By using blocking methods, the matrix elements of R are grouped into equivalent 4×4 matrix blocks, with residual interactions, which are then put in correspondence with the sites of a rectangular lattice, thereby making the problem isomorphic to that of finding a noninteracting one-electron Green's function in the Wannier representation. (4) Renormalized perturbation theory, along with a series of convolution theorems due to Hugenholtz and Van Hove, allows one to develop a self-consistency equation that automatically takes into account an infinite number of configurations. The resulting DOS is compared with photoemission spectra from hydrogen adsorbed on tungsten (half-filled metal band) and nickel (almost full). Correlation effects turn out to produce peaks at the appropriate energies, so that an unusually good agreement is found despite the featureless, semielliptical DOS adopted for the metal. Only gross features of this quantity, such as width, center, and occupation of the band, seem to matter in a photoemission calculation.

  3. Beyond Néel's theories: thermal demagnetization of narrow-band partial thermoremanent magnetizations

    NASA Astrophysics Data System (ADS)

    Dunlop, David J.; Özdemir, Özden

    2001-10-01

    Partial thermoremanent magnetization (pTRM) was imparted over a narrow temperature interval, T=370-350°C, to a suite of crushed and annealed natural magnetite samples, ranging in grain size from ?1 to 125-150 ?m and in domain state from small pseudo-single-domain (PSD) to multidomain (MD). In this way, effectively a single blocking temperature, TB, of pTRM was activated. Stepwise thermal demagnetization did not erase the pTRMs sharply at TB, as for single-domain (SD) grains. Demagnetization began well below 350°C and continued above 370°C, with a median unblocking temperature, TUB, close to 360°C. The largest grains deviated most from SD behavior. Their pTRM demagnetized over the entire interval from room temperature to the Curie point, in accordance with predictions for MD grains. In terms of the unblocking temperature distribution f( TUB) or slope d M/d T of the thermal demagnetization curve, SD grains have a sharp spectrum, TUB= TB; MD grains were observed to have a broad, roughly symmetrical spectrum centered on TB; and intermediate size grains in the PSD range had non-Gaussian spectra, combining a central peak near TB with broad tails above and below TB. In this respect, PSD grains display a superposition of SD and MD remanences, not a blend between the two. Practical implications of these observations are that Thellier's law of reciprocity ( TUB= TB) will be increasingly violated as grain size increases in the PSD range. The low- TUB part of f( TUB) produces anomalously large demagnetization of NRM in low-temperature heating steps of Thellier-type paleointensity determinations and a sagging shape of the Arai plot. The high- TUB part of f( TUB) results in undemagnetized remanence at and above TB in thermal demagnetization. Among pre-treatments designed to make remanence more SD-like in subsequent thermal cleaning, alternating field (AF) pre-cleaning sharpened f( TUB) more effectively than low-temperature demagnetization for the 20 ?m sample.

  4. 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

  5. Crystal lattice spacing shrinkage and band-gap narrowing phenomena in In-doped SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Feng, Caili; Duan, Junhong; Liu, Gang

    2015-04-01

    Pure and In-doped Tin Oxide (SnO2) nanoparticles with different doping concentration were prepared by hydrothermal method. The prepared samples were characterized by XRD, TEM, and UV–vis absorption spectroscopy. The crystal lattice spacing d of In-doped SnO2 nanoparticles decreases compared with pure SnO2. The crystal lattice spacing ratios ? d/d for (110), (101) and (211) crystal face shrinks acutely with 1.9% doping in SnO2. Crystallite size calculated by the FWHM of the first major XRD peaks (110) decreases from 3.945 to 3.281 nm as the doping concentration increases from 0 to 10%, whereas the strain increases. XRD study reveals that crystal lattice spacing of SnO2 nanoparticles shrinks due to the effect of In element doping. Optical band-gap of SnO2 nanoparticles decreases from 3.76 to 3.33 eV first, and then increases to 3.55 and 3.52 eV, respectively, as the doping concentration changes from 1.9, 3.8 to 10%. Band-gap narrowing originates from the effect of crystal lattice spacing shrinkage.

  6. High-frequency response and the possibilities of frequency-tunable narrow-band terahertz amplification in resonant tunneling nanostructures

    SciTech Connect

    Kapaev, V. V., E-mail: kapaev@sci.lebedev.ru; Kopaev, Yu. V.; Savinov, S. A.; Murzin, V. N. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)] [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2013-03-15

    The characteristics of the high-frequency response of single- and double-well resonant tunneling structures in a dc electric field are investigated on the basis of the numerical solution of a time-dependent Schroedinger equation with open boundary conditions. The frequency dependence of the real part of high frequency conductivity (high-frequency response) in In{sub 0.53}Ga{sub 0.47}As/AlAs/InP structures is analyzed in detail for various values of the dc voltage V{sub dc} in the negative differential resistance (NDR) region. It is shown that double-well three-barrier structures are promising for the design of terahertz-band oscillators. The presence of two resonant states with close energies in such structures leads to a resonant (in frequency) response whose frequency is determined by the energy difference between these levels and can be controlled by varying the parameters of the structure. It is shown that, in principle, such structures admit narrow-band amplification, tuning of the amplification frequency, and a fine control of the amplification (oscillation) frequency in a wide range of terahertz frequencies by varying a dc electric voltage applied to the structure. Starting from a certain width of the central intermediate barrier in double-well structures, one can observe a collapse of resonances, where the structure behaves like a single-well system. This phenomenon imposes a lower limit on the oscillation frequency in three-barrier resonant tunneling structures.

  7. Are PAH molecules the carriers of Unidentified Infrared Emission bands?

    NASA Astrophysics Data System (ADS)

    Kwok, Sun; Zhang, Yong

    2015-01-01

    Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered as the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper we report the result of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal and even artificial spectra) using the theoretical infrared spectra of PAHs from the NASA Ames PAH IR Spectroscopic Database. We show that these non-PAH spectra can be well fitted by PAH mixtures. This suggest that a general match between astronomical spectra and those of PAH mixtures does not necessarily provide definitive support for the PAH hypothesis.

  8. Origin of Narrow-band and Broadband Noise in Conduction Noise Spectra of Bi_2Sr_2CaCu_2O_y

    Microsoft Academic Search

    A. Maeda; Y. Togawa; R. Abiru; H. Kitano

    2001-01-01

    Conduction noise spectra were investigated in the driven vortex state of a high-temperature superconductor, Bi_2Sr_2CaCu_2Oy single crystals. Two characteristic noise features, a broad-band noise (BBN) and a narrow-band noise (NBN), were observed in the vortex solid phase. The NBN was found to originate from the washboard modulation of the translational velocity of the driven vortices [1]. To clarifify the origin

  9. Charge and spin fluctuations Cu2+(S=1\\/2)Cu3+(S=1)in HTSCs. new model of narrow impurity bands

    Microsoft Academic Search

    Mikhail Eremin; Oleg Anikeenok

    1991-01-01

    The energy band of oxide superconductors is theoretically investigated when charge and spin fluctuations of Cu2+ (S=1\\/2)-O- (S=0) Cu3+ (S=1)-O2- (S=1\\/2) take place. It is shown that two narrow bands arise near Fermi level under hole doping. The dynamic admixture of 3z2-r2 state to the x2-y2 state is equal to approximately 10%.

  10. 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.

  11. IEEE JOURNAL OF OCEANIC ENGINEERING, VOL. OE-3, NO.1,JANUARY 1978 5 Passive SystemsTheory with Narrow-Band and

    E-print Network

    Moura, José

    Theory with Narrow-Band and Linear Constraints:Part I-Spatial Diversity JOSE M.F. MOURA AND ARTHUR E. BAGGEROER was supportedbythe J.S.E.P., underContract DAAB07-71- C-0300. J. M. F. Moura is with Centro De Anilk e

  12. 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.

  13. Identifying AGN Balmer absorptions and stratified narrow emission-line region kinematics in SDSS J112611.63+425246.4

    NASA Astrophysics Data System (ADS)

    Wang, J.; Xu, D. W.

    2015-01-01

    Context. Balmer absorption is a rare phenomenon in active galactic nuclei (AGNs). So far, only seven Balmer-absorption AGNs have been reported in the literature. Aims: We here report the identification of SDSS J112611.63+425246 as a new Balmer-absorption AGN through our spectral analysis and study the kinematics of its narrow emission-line region (NLR). Methods: We modeled the continuum by a linear combination of a starlight component, a power law from the central AGN, and the emission from the FeII complex. After subtracting the modeled continuum, each emission or absorption line profile is a sum of multi-Gaussian functions. All the line shifts were determined with respect to the modeled starlight component. Results: By using the host starlight as a reference for the local system, both H? and H? show AGN absorptions with a blueshift of ~300 km s-1. We identify a strong anticorrelation between the inferred velocity shifts and the ionization potential for various narrow emission lines, which suggests a stratified NLR kinematics. A de-accelerated outflow is implied for the inner NLR gas, an accelerated inflow for the outer NLR gas. This complicated NLR kinematics additionally implies that AGN narrow emission lines, even for the low-ionized lines, might not be a reliable substitute for the velocity of the local system.

  14. 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

  15. 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

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

    E-print Network

    Andrzej Pisarski; Piotr Jaranowski

    2014-12-18

    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 thus assume that both the position of the gravitational-wave source in the sky and the wave's frequency together with spindown parameters 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. All 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. Our template banks are suitable for larger range of search parameters than the banks previously proposed and compared to them they have 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 recent all-sky $\\mathcal{F}$-statistic-based search for continuous gravitational waves in Virgo VSR1 data.

  17. 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

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

    NASA Astrophysics Data System (ADS)

    Pisarski, Andrzej; Jaranowski, Piotr

    2015-07-01

    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 a simplified model of the signal with constant amplitude and phase which is a linear function of unknown parameters. Our template banks enable the usage of the fast Fourier transform algorithm in the computation of the maximum-likelihood {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 {F}-statistic-based search for continuous gravitational waves in Virgo VSR1 data (Aasi et al 2014 Class. Quantum Grav. 31 165014). Here we improve that template bank by constructing templates suitable for a larger range of search parameters and of smaller thicknesses for certain values of search parameters. One of our template banks has a thickness 12% smaller than that of the template bank used in the all-sky search of Virgo VSR1 data and only 4% larger than the thickness of the four-dimensional optimal lattice covering {A}4\\star .

  19. 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 ...

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

    SciTech Connect

    Astone, Pia [Istituto Nazionale di Fisica Nucleare, (INFN)-Rome I, 00185 Rome (Italy); Borkowski, Kazimierz M. [Centre for Astronomy, Nicolaus Copernicus University, Gagarina 11, 87-100 Torun (Poland); Jaranowski, Piotr; Pietka, Maciej [Faculty of Physics, University of Bialystok, Lipowa 41, 15-424 Bialystok (Poland); Krolak, Andrzej [Institute of Mathematics, Polish Academy of Sciences, Sniadeckich 8, 00-950 Warsaw (Poland)

    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.

  1. The Role of Narrow Band Imaging in the Detection of Recurrent Laryngeal and Hypopharyngeal Cancer after Curative Radiotherapy

    PubMed Central

    Zabrodsky, Michal; Plzak, Jan

    2014-01-01

    Narrow band imaging is considered a significant improvement in the possibility of detecting early mucosal lesion of the upper aerodigestive tract. Early detection of mucosal neoplastic lesions is of utmost importance for patients survival. There is evidence that, especially in patients previously treated by means of curative radiotherapy or chemoradiotherapy, the early detection rate of recurrent disease is quite low. The aim of this study was to prove whether the videoendoscopy coupled with NBI might help detect recurrent or secondary tumors of the upper aerodigestive tract. 66 patients previously treated by means of RT or CRT with curative intent were enrolled in the study. All patients underwent transnasal flexible videoendoscopy with NBI mode under local anesthesia. When a suspicious lesion was identified in an ambulatory setting, its nature was proved histologically. Many of these changes were not identifiable by means of conventional white light (WL) endoscopy. The accuracy, sensitivity, specificity, and positive and negative predictive value of the method are very high (88%, 92%, 76%, 96%, and 91%, resp.). Results demonstrate that outpatient transnasal endoscopy with NBI is an excellent method for the follow-up of patients with carcinomas of the larynx and the hypopharynx primarily treated with radiotherapy. PMID:25101264

  2. THE DIFFERENCE IN NARROW Fe K{alpha} LINE EMISSION BETWEEN SEYFERT 1 AND SEYFERT 2 GALAXIES

    SciTech Connect

    Liu Teng; Wang Junxian, E-mail: lewtonstein@gmail.co, E-mail: jxw@ustc.edu.c [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China (China)

    2010-12-20

    We compile a sample of 89 Seyfert galaxies with both [O IV] 25.89 {mu}m line luminosities observed by Spitzer IRS and X-ray spectra observed by XMM-Newton EPIC. Using [O IV] emission as a proxy for active galactic nucleus (AGN) intrinsic luminosity, we find that although type 2 AGNs have higher line equivalent widths, the narrow Fe K{alpha} lines in Compton-thin and Compton-thick Seyfert 2 galaxies are 2.9{sup +0.8}{sub -0.6} and 5.6{sup +1.9}{sub -1.4} times weaker in terms of luminosity than Seyfert 1 galaxies, respectively. This indicates that different correction factors need to be applied for various types of AGNs before the narrow Fe K{alpha} line luminosity could serve as an intrinsic AGN luminosity indicator. We also find that Seyfert 1 galaxies in our sample have on average marginally larger line widths and higher line centroid energies, suggesting contamination from highly ionized Fe line or broader line emission from much smaller radius, but this effect is too weak to explain the large difference in narrow Fe K{alpha} line luminosity between type 1 and type 2 AGNs. This is the first observational evidence showing that the narrow Fe K{alpha} line emission in AGNs is anisotropic. The observed difference is consistent with theoretical calculations assuming a smoothly distributed obscuring torus and could provide independent constraints on the clumpiness of the torus.

  3. 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.

  4. Time-Domain Emission Measurements in K-Band

    NASA Astrophysics Data System (ADS)

    Hoffmann, Christian; Russer, Peter

    2011-08-01

    The presented time-domain EMI measurement system allows for full-compliance measurements according to CISPR 16-1-1 in the frequency range from 9 kHz to 26 GHz. With the combination of ultra-fast analog-to-digital-conversion and real-time digital signal processing on a field-programmable-gate-array (FPGA) with ultra-broadband multi-stage down-conversion, time-domain methods are employed for measurements into K-band. This allows for a reduction in scan times by several orders of magnitude. A scan from 9 kHz to 26 GHz with a 9 kHz IF-filter bandwidth is completed in under 200 s, while over 5 · 106 frequency points are calculated. The use of low-loss components and integrated preamplifiers yields an ultra-low system noise floor power spectral density of typically below -150 dBm/Hz. The system IF dynamic range of over 60 dB allows for the measurement of high-dynamic range signals like radar pulses. Measurements of the radiated emissions of a personal computer and the nonstationary emissions of a microwave oven are presented.

  5. Stability of a reflective coupling diode with the inclusion of thermal effects in narrow band-gap This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-print Network

    Gilbert, Matthew

    Stability of a reflective coupling diode with the inclusion of thermal effects in narrow band-1242(04)72447-5 Stability of a reflective coupling diode with the inclusion of thermal effects in narrow band-gap materials the difficulty in fabrication, resonant tunnelling diodes (RTD) have found a great deal of usage in the analogue

  6. 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.

  7. 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.

  8. Narrow He II emission in star-forming galaxies at low metallicity. Stellar wind emission from a population of Very Massive Stars

    E-print Network

    Gräfener, G

    2015-01-01

    In a recent study star-forming galaxies with HeII emission at moderate redshifts have been found to occur in two modes, distinguished by the width of their HeII emission lines. Broad HeII emission has been attributed to stellar emission from a population of evolved Wolf-Rayet (WR) stars while narrow HeII emission has been attributed to nebular emission excited by a population of very hot PopIII stars formed in pockets of pristine gas at moderate redshifts. In this work we propose an alternative scenario for the origin of the narrow HeII 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. We estimate the expected HeII line fluxes and equivalent widths based on wind models for VMS and population synthesis models, and compare the results with recent observations of star-forming galaxies at moderate redshifts. The observed HeII line strengths and equivalent widths are in line with what is expected for a po...

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

    Microsoft Academic Search

    D. Nötzold

    1997-01-01

    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

  10. Optimal focusing for maximal collection of entangled narrow-band photon pairs into single-mode fibers

    SciTech Connect

    Ljunggren, Daniel; Tengner, Maria [Department of Microelectronics and Information Technology, Royal Institute of Technology, KTH, Electrum 229, SE-164 40 Kista (Sweden)

    2005-12-15

    We present a theoretical and experimental investigation of the emission characteristics and the flux of photon pairs generated by spontaneous parametric downconversion in quasi-phase matched bulk crystals for the use in quantum communication sources. We show that, by careful design, one can attain well defined modes close to the fundamental mode of optical fibers and obtain high coupling efficiencies also for bulk crystals, these being more easily aligned than crystal waveguides. We distinguish between singles coupling, {gamma}{sub s} and {gamma}{sub i}, conditional coincidence, {mu}{sub i|s}, and pair coupling, {gamma}{sub c}, and show how each of these parameters can be maximized by varying the focusing of the pump mode and the fiber-matched modes using standard optical elements. Specifically we analyze a periodically poled KTP-crystal pumped by a 532 nm laser creating photon pairs at 810 nm and 1550 nm. Numerical calculations lead to coupling efficiencies above 93% at optimal focusing, which is found by the geometrical relation L/z{sub R} to be {approx_equal}1 to 2 for the pump mode and {approx_equal}2 to 3 for the fiber-modes, where L is the crystal length and z{sub R} is the Rayleigh-range of the mode-profile. These results are independent on L. By showing that the single-mode bandwidth decreases {proportional_to}1/L, we can therefore design the source to produce and couple narrow bandwidth photon pairs well into the fibers. Smaller bandwidth means both less chromatic dispersion for long propagation distances in fibers, and that telecom Bragg gratings can be utilized to compensate for broadened photon packets--a vital problem for time-multiplexed qubits. Longer crystals also yield an increase in fiber photon flux {proportional_to}{radical}(L), and so, assuming correct focusing, we can only see advantages using long crystals.

  11. Computer-aided diagnosis in endoscopy: a novel application toward automatic detection of abnormal lesions on magnifying narrow-band imaging endoscopy in the stomach.

    PubMed

    Lee, Tsung-Chun; Lin, Yu-Huei; Uedo, Noriya; Wang, Hsiu-Po; Chang, Hsuan-Ting; Hung, Chung-Wen

    2013-01-01

    Gastric cancer is the fourth common cancer and the second major cause of cancer death worldwide. Early detection of gastric cancer by endoscopy surveillance is actively investigated to improve patient survival, especially using the newly developed magnifying narrow-band imaging endoscopy in the stomach. However, meticulous examination of the aforementioned images is both time and experience demanding and interpretation could be variable among different doctors, which hindered its widespread application. In this study, we developed a new image analysis system by adopting local binary pattern and vector quantization to perform pattern comparison between known training abnormal images and testing images of magnifying narrow band endoscopy images in the stomach. Our preliminary results demonstrated promising potential for automatically labeled region of interest for endoscopy doctors to focus on abnormal lesions for subsequent targeted biopsy, with the rates of recall 0.46-1.00 and precision 0.39-0.87. PMID:24110716

  12. Prospective clinical and histological study to evaluate the efficacy and safety of a targeted high?intensity narrow band UVB\\/UVA1 therapy for striae alba

    Microsoft Academic Search

    Neil S. Sadick; Cynthia Magro; Alison Hoenig

    2007-01-01

    Objective: The purpose of this study was to determine the efficacy and safety of a targeted narrow band UVB\\/UVA1 therapy for the treatment of striae alba. Methods: Fourteen individuals with skin types II-VI were enrolled in this 22-week trial that consisted of up to 10 treatments with a combination of UVB\\/UVA1 (MultiClear2, Curelight Ltd, Israel). Participants were treated with a

  13. Thermopower and specific heat of the organic molecular salt (TMTSF)2ClO4: observation of the narrow band response

    Microsoft Academic Search

    Cheng-Hai Sun; Hong-Shun Yang; Jian Liu; Hui-Xian Gao; Jian-Bin Wang; Lu Cheng; Lie-Zhao Cao; J. C. Lasjaunias

    2008-01-01

    Measurements of thermopower Sa(T) along the highly conducting a axis and specific heat of the Bechgaard salts (TMTSF)2ClO4 for various cooling rates through the anion ordering temperature Ta = 24 K were carried out. Sign reversal in Sa(T) is found below Ta and it decreases with increasing cooling rate, which is attributed to the change of a narrow band filling

  14. Accuracy of narrow-band and global models for radiative transfer in H2O, CO2, and H2O-CO2 mixtures at high temperature.

    NASA Astrophysics Data System (ADS)

    Pierrot, L.; Soufiani, A.; Taine, J.

    1999-07-01

    The accuracy of several narrow-band (SNB, CK, CKFG) and global (WSGG, SLW, ADF, ADFFG) gas infrared radiative property models applied to radiative transfer in a planar geometry with different types of temperature profiles is studied. The considered gaseous mixtures are H2O-N2, CO2-N2 and H2O-CO2-N2. Reference solutions are provided by line-by-line (LBL) calculations. All model parameters are based on the same spectroscopic data bases so that only the intrinsic accuracy of each model is tested. All narrow-band models lead in most cases to accurate results, but errors induced by the transmissivity based models SNB and CKFG increase with wall reflectivity if the reflected radiation is assumed spectrally uncorrelated with gaseous transmissivity. Global models are less time consuming than narrow-band models but are generally less accurate and limited to media with gray boundaries and/or participating particles. The WSGG model leads in many cases to very important errors. The relative accuracy of the SLW and ADF models is typically about 10-20% but care must be taken in the choice of the reference temperature. The ADFFG model is the most accurate global model but requires greater computing times than the ADF and SLW models. For long range sensing of hot gases, only the fictitious-gas based models CKFG and ADFFG lead to accurate results. In the case of mixtures containing H2O and CO2, the spectral uncorrelation assumption is accurate for narrow-band models and its implementation results only in greater computing times for the CK model. This assumption is not generally accurate for the whole spectra and specific parameters must be generated from the joint distribution function of the absorption coefficients in the case of global models.

  15. Selective and reversible control of a chemical reaction with narrow-band infrared radiation: HXeCC radical in solid xenon

    Microsoft Academic Search

    Leonid Khriachtchev; Hanna Tanskanen; Markku Räsänen

    2007-01-01

    The light-induced H+XeC2 ?HXeCC reaction is studied in solid Xe, and the full optical control of this reaction is demonstrated. By narrow-band excitation in the IR spectral region, HXeCC radicals can be decomposed to a local metastable configuration and then selectively recovered by resonant excitation of the XeC 2 vibrations. The novel recovery process is explained by short-range mobility of

  16. Comparison of narrow-band reflectance spectroscopy and tristimulus colorimetry for measurements of skin and hair color in persons of different biological ancestry

    Microsoft Academic Search

    Mark D. Shriver; Esteban J. Parra

    2000-01-01

    We have used two modern computerized handheld reflectome- ters, the Photovolt ColorWalk colorimeter (a tristimulus colorimeter; Photovolt, UMM Electronics, Indianapolis, IN) and the DermaSpectrometer (a specialized narrow-band reflectometer; Cortex Technology, Hadsund, Denmark), to compare two methods for the objective determination of skin and hair color. These in- struments both determine color by measuring the intensity of reflected light of particular

  17. 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.

  18. Detection of KS -band Thermal Emission from WASP-3b

    NASA Astrophysics Data System (ADS)

    Zhao, Ming; Milburn, Jennifer; Barman, Travis; Hinkley, Sasha; Swain, Mark R.; Wright, Jason; Monnier, John D.

    2012-03-01

    We report the detection of thermal emission from the hot Jupiter WASP-3b in the KS 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 ~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?)—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 ? 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.

  19. NARROW DOUBLE-PEAKED EMISSION LINES OF SDSS J131642.90+175332.5: SIGNATURE OF A SINGLE OR A BINARY AGN IN A MERGER, JET-CLOUD INTERACTION, OR UNUSUAL NARROW-LINE REGION GEOMETRY

    SciTech Connect

    Xu Dawei [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Komossa, S., E-mail: dwxu@bao.ac.c, E-mail: skomossa@mpe.mpg.d [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, 85741 Garching (Germany)

    2009-11-01

    We present an analysis of the active galaxy SDSS J131642.90+175332.5, which is remarkable because all of its narrow emission lines are double-peaked, and because it additionally shows an extra broad component (FHWM approx 1400 km s{sup -1}) in most of its forbidden lines, peaking in between the two narrow systems. The peaks of the two narrow systems are separated by 400-500 km s{sup -1} in velocity space. The spectral characteristics of double-peaked [O III] emission have previously been interpreted as a signature of dual or binary active galactic nuclei (AGNs), among other models. In the context of the binary scenario, SDSS J131642.90+175332.5 is a particularly good candidate because not just one line but all of its emission lines are double-peaked. However, we also discuss a number of other scenarios which can potentially account for double-peaked narrow emission lines, including projection effects, a two-sided outflow, jet-cloud interactions, special narrow-line region (NLR) geometries (disks, bars, or inner spirals), and a galaxy merger with only one AGN illuminating two NLRs. We argue that the similarity of the emission-line ratios in both systems, and the presence of the very unusual broad component at intermediate velocity, makes a close pair of unrelated AGNs unlikely, and rather argues for processes in a single galaxy or merger. We describe future observations that can distinguish between these remaining possibilities.

  20. Turboprop and rotary-wing aircraft flight parameter estimation using both narrow-band and broadband passive acoustic signal-processing methods.

    PubMed

    Ferguson, B G; Lo, K W

    2000-10-01

    Flight parameter estimation methods for an airborne acoustic source can be divided into two categories, depending on whether the narrow-band lines or the broadband component of the received signal spectrum is processed to estimate the flight parameters. This paper provides a common framework for the formulation and test of two flight parameter estimation methods: one narrow band, the other broadband. The performances of the two methods are evaluated by applying them to the same acoustic data set, which is recorded by a planar array of passive acoustic sensors during multiple transits of a turboprop fixed-wing aircraft and two types of rotary-wing aircraft. The narrow-band method, which is based on a kinematic model that assumes the source travels in a straight line at constant speed and altitude, requires time-frequency analysis of the acoustic signal received by a single sensor during each aircraft transit. The broadband method is based on the same kinematic model, but requires observing the temporal variation of the differential time of arrival of the acoustic signal at each pair of sensors that comprises the planar array. Generalized cross correlation of each pair of sensor outputs using a cross-spectral phase transform prefilter provides instantaneous estimates of the differential times of arrival of the signal as the acoustic wavefront traverses the array. PMID:11051503

  1. Estimation of global solar UV index from UV-B irradiance measured with a narrow-band UV-B radiometer

    NASA Astrophysics Data System (ADS)

    Takeshita, Shu; Sasaki, Masako

    2005-08-01

    The global solar UV index is an indicator for notifying the level of harmful solar ultraviolet radiation reaching the surface of the earth and the general public. It was proposed by the WHO/WMO/UNEP/ICNIRP and was standardized by the CIE in 2003. This index is derived from the product of the spectral solar UV irradiance from 250 to 400 nm and the CIE standard of reference erythema spectrum. For calculation of the UV index, the measurement of spectral solar UV irradiance is needed. Spectral radiometry is the best method of measurement of solar UV irradiance, however spectral radiometers are cost prohibitive. On the other hand, a narrow-band solar UV-B radiometer is widely used for measurement of solar UV-B irradiance in the world. The Tokai Solar Radiation Monitoring Network, and the UV Monitoring Network-Japan performed by the National Institute for Environmental Studies are two examples of monitoring networks using narrow-band solar UV-B radiometer in Japan. In this paper an estimation method of the UV index from the measured UV-B irradiance with the narrow-band UV-B radiometer.

  2. Narrow polarized components in the OH 1612-MHz maser emission from supergiant OH-IR sources

    NASA Technical Reports Server (NTRS)

    Cohen, R. J.; Downs, G.; Emerson, R.; Grimm, M.; Gulkis, S.; Stevens, G.

    1987-01-01

    High-resolution (300 Hz) OH 1612-MHz spectra of the supergiant OH-IR sources VY CMa, VX Sgr, IRC 10420, and NML Cyg are presented. Linewidths as small as 550 Hz (0.1 km/s) are found for narrow components in the spectra. The present results are consistent with current models for maser line-narrowing and for the physical properties in the OH maser regions. A significant degree of circular polarization is noted in many of the narrow components. The circular polarization suggests the presence of magnetic fields of about 1 mG in the circumstellar envelopes which would be strong enough to influence the outflow from the stars, and which may explain asymmetries found in the circumstellar envelopes.

  3. [O III] emission line in narrow-line Seyfert 1 galaxies

    E-print Network

    Weihao Bian; Qirong Yuan; Yongheng Zhao

    2006-02-01

    Three sets of two-component profiles are used to simultaneously model the [O III]$\\lambda\\lambda$4959, 5007 and H$\\beta$ lines for the Fe II-subtracted spectra of 149 narrow line Seyfert 1 galaxies (NLSls) from the Sloan Digital Sky Survey (SDSS). Using the linewidth of the narrow/core component of [O III]$\\lambda$5007 to trace the stellar velocity dispersion instead of using the total linewidth of [O III]$\\lambda$5007, we found that the SDSS NLSls are still deviated from the $M_{bh}-\\sigma$ relation found in the nearby inactive galaxies, suggesting that the linewidth of the [O III] narrow/core component is likely not a good tracer of bulge velocity dispersion in NLSls, since some other studies indicate that NLS1s, like other AGN, should follow the $M_{bh}-\\sigma$ relation. If we assume that the [O III]5007/H$\\beta_{n}$ line ratio emitted in narrow line region ranges from one to ten, 63 objects are found to satisfied with this criterion and their H$\\beta$ broad components should be used to calculate their virial black hole masses. These 63 objects are statically consistent with the $M_{bh}-\\sigma_{[O III]}$ relation. With the Chandra observation of some SDSS NLSls, for one object in these 63 objects, J143030.22-001115.1, we found that it can't be classified as a genuine NLS1. Its narrow component of H$\\beta$ is coming from narrow line regions (NLRs). This is consistent with its very flat hard X-ray spectrum found by williams et al. (2004).

  4. RESOLVED MID-INFRARED EMISSION IN THE NARROW-LINE REGION OF NGC 4151 James T. Radomski, Robert K. Pin~a, Christopher Packham, and Charles M. Telesco

    E-print Network

    De Buizer, James Michael

    RESOLVED MID-INFRARED EMISSION IN THE NARROW-LINE REGION OF NGC 4151 James T. Radomski, Robert K; accepted 2002 November 26 ABSTRACT We present subarcsecond-resolution mid-infrared images of NGC 4151 at 10). The mid-infrared emission from NGC 4151 has been sug- gested as arising from either thermal emission from

  5. First results from the FPGA/NIOS Adaptive FIR Filter Using Linear Prediction Implemented in the AERA Radio Stations to Reduce Narrow Band RFI for Radio Detection of Cosmic Rays

    E-print Network

    Szadkowski, Zbigniew; Timmermans, C

    2014-01-01

    The FPGA/NIOS FIR filter based on linear prediction (LP) to suppress radio frequency interference (RFI) has been installed in several radio stations in the Auger Engineering Radio Array (AERA) experiment. AERA observes coherent radio emission from extensive air showers induced by ultra-high-energy cosmic rays to make a detailed study of the development of the electromagnetic part of air showers. Radio signals provide complementary information to that obtained from Auger surface detectors, which are predominantly sensitive to the particle content of an air shower at the surface. The radio signals from air showers are caused by the coherent emission due to geomagnetic and charge-excess processes. These emissions can be observed in the frequency band between 10 - 100 MHz. However, this frequency range is significantly contaminated by narrow-band RFI and other human-made distortions. A FIR filter implemented in the FPGA logic segment of the front-end electronics of a radio sensor significantly improves the signal...

  6. 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.

  7. 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 [Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049 (China); Bai Jinming, E-mail: wangjm@mail.ihep.ac.cn [Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011 (China)

    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.

  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. Band-structure effects in photoelectron-emission spectra from metal surfaces

    NASA Astrophysics Data System (ADS)

    Rios Rubiano, C. A.; Gravielle, M. S.; Mitnik, D. M.; Silkin, V. M.

    2012-04-01

    Photoelectron emission from the valence band of a metal surface due to the grazing incidence of ultrashort laser pulses is studied in the framework of a distorted-wave formulation. We propose a model, named the band-structure-based-Volkov (BSB-V) approximation, which takes into account the contribution of the band structure of the solid. The BSB-V approach is applied to calculate differential electron-emission probabilities for Al(111) and Be(0001) surfaces. A noticeable influence of the electronic band structure was observed in the case of beryllium, while for aluminum such effects were found to play a minor role.

  10. Mid- and far-infrared emission bands in C-rich proto-planetary nebulae

    NASA Technical Reports Server (NTRS)

    Omont, A.; Cox, P.; Moseley, S. Harvey; Glaccum, W.; Casey, Sean; Forveille, T.; Szczerba, R.; Chan, Kin-Wing

    1995-01-01

    The 16-48 micron spectra of five carbon-rich post-asymptotic giant branch (post-AGB) objects known to have an unidentified 21 micron feature in their IRAS low resolution spectrometer (LRS) spectra have been obtained using the Kuiper Airborne Observatory. A broad emission band extending from 24 to approximately 45 microns is present in the spectra of these objects. The strength of this band is variable from source to source and is not correlated with the strength of the 21 micron band. The possible identifications for the emitting material of both the 21 and 30 micron emission bands is discussed.

  11. Reduction of timing jitter and intensity noise in normal-dispersion passively mode-locked fiber lasers by narrow band-pass filtering.

    PubMed

    Qin, Peng; Song, Youjian; Kim, Hyoji; Shin, Junho; Kwon, Dohyeon; Hu, Minglie; Wang, Chingyue; Kim, Jungwon

    2014-11-17

    Fiber lasers mode-locked with normal cavity dispersion have recently attracted great attention due to large output pulse energy and femtosecond pulse duration. Here we accurately characterized the timing jitter of normal-dispersion fiber lasers using a balanced cross-correlation method. The timing jitter characterization experiments show that the timing jitter of normal-dispersion mode-locked fiber lasers can be significantly reduced by using narrow band-pass filtering (e.g., 7-nm bandwidth filtering in this work). We further identify that the timing jitter of the fiber laser is confined in a limited range, which is almost independent of cavity dispersion map due to the amplifier-similariton formation by insertion of the narrow bandpass filter. The lowest observed timing jitter reaches 0.57 fs (rms) integrated from 10 kHz to 10 MHz Fourier frequency. The rms relative intensity noise (RIN) is also reduced from 0.37% to 0.02% (integrated from 1 kHz to 5 MHz Fourier frequency) by the insertion of narrow band-pass filter. PMID:25402069

  12. The visible to the near infrared narrow band acousto-optic tunable filter and the hyperspectral microscopic imaging on biomedicine study

    NASA Astrophysics Data System (ADS)

    Zhang, Chunguang; Wang, Hao; Huang, Junfeng; Gao, Qiang

    2014-12-01

    Based on the parallel tangents momentum-matching condition, a narrow band noncollinear acousto-optic tunable filter (AOTF) using a single TeO2 crystal is designed with the consideration of the birefringence and the rotatory property of the material. An effective setup is established to evaluate the performance of the designed AOTF. The experimental observed spectrum pattern of the diffracted light is nearly the same with the theoretical result. The measured tuning relationship between the diffracted central optical wavelength and acoustic frequency is in accordance with the theoretical prospect. The optical bandwidth of the diffracted light is as narrow as 1.88 nm when the central wavelength is 556.75 nm. The high spectral resolution is significant in practical applications of imaging AOTF. Additionally, the AOTF based hyperspectral microscopic imaging system is established. The stability and the image resolution of the designed narrow band AOTF are satisfying. Finally, the study of the biologic samples indicates the feasibility of our system on biomedicine.

  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. 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

  16. Quasi-random narrow-band model FITS to near-infrared low-temperature laboratory methane spectra and derived exponential-sum absorption coefficients

    NASA Astrophysics Data System (ADS)

    Baines, K. H.; West, R. A.; Giver, L. P.; Moreno, F.

    1993-03-01

    Near-infrared 10/cm resolution spectra of methane obtained at various temperatures, pressures, and abundances are fit to a quasi-random narrow-band model. Exponential-sum absorption coefficients for three temperatures (112, 188, and 295 K), and 20 pressures from 0.0001 to 5.6 bars, applicable to the cold environments of the major planets, are then derived from the band model for the 230 wavelengths measured from 1.6 to 2.5 microns. RMS deviations between the laboratory and the exponential-sum synthetic transmissions are reported for the best fitting 50 wavelengths. Deviations relevant to broadband, 1-percent spectral resolution observations are also presented. The validity of exponential-sum coefficients derived from broadband (10/cm) transmission data is demonstrated via direct comparison with line-by-line calculations. The complete atlas of coefficients is available from the Planetary Data System-Planetary Atmospheres Discipline Node.

  17. 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

  18. 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.

  19. Detection of marine methane emissions with AVIRIS band ratios

    Microsoft Academic Search

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

    2011-01-01

    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

  20. Controlling spontaneous emission in photonic-band-gap materials doped with nanoparticles

    SciTech Connect

    Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London N6A 3K7 (Canada)

    2007-03-15

    The phenomenon of spontaneous emission cancellation has been investigated in photonic-band-gap materials in the presence of dipole-dipole interaction. The material is densely doped with an ensemble of five-level nanoparticles. The mean field theory is used to calculate the effect of the dipole-dipole interaction whereas the linear response theory is used to calculate the expressions for the real and imaginary susceptibilities. Numerical simulations are performed for an isotropic photonic-band-gap material. Interesting results are predicted such as the control of the spontaneous emission cancellation by moving the resonance energies between the energy band and energy gap. It is also found that the photonic-band-gap material can be switched between absorptive and nonabsorptive states by changing the strength of the dipole-dipole interaction and the resonance energies in the energy band.

  1. 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.

  2. Fermi\\/Large Area Telescope Discovery of Gamma-Ray Emission from a Relativistic Jet in the Narrow-Line Quasar PMN J0948+0022

    Microsoft Academic Search

    A. A. Abdo; M. Ackermann; M. Ajello; M. Axelsson; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; M. Battelino; B. M. Baughman; K. Bechtol; R. Bellazzini; E. D. Bloom; E. Bonamente; A. W. Borgland; J. Bregeon; A. Brez; M. Brigida; P. Bruel; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; J. M. Casandjian; E. Cavazzuti; C. Cecchi; A. Chekhtman; C. C. Cheung; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; W. Collmar; J. Conrad; L. Costamante; C. D. Dermer; A. de Angelis; F. de Palma; S. W. Digel; E. do Couto e. Silva; P. S. Drell; R. Dubois; D. Dumora; C. Farnier; C. Favuzzi; W. B. Focke; L. Foschini; M. Frailis; L. Fuhrmann; Y. Fukazawa; S. Funk; P. Fusco; F. Gargano; N. Gehrels; S. Germani; B. Giebels; N. Giglietto; F. Giordano; M. Giroletti; T. Glanzman; I. A. Grenier; M.-H. Grondin; J. E. Grove; L. Guillemot; S. Guiriec; Y. Hanabata; A. K. Harding; R. C. Hartman; M. Hayashida; E. Hays; R. E. Hughes; G. Jóhannesson; A. S. Johnson; R. P. Johnson; W. N. Johnson; T. Kamae; H. Katagiri; J. Kataoka; M. Kerr; J. Knödlseder; F. Kuehn; M. Kuss; J. Lande; L. Latronico; M. Lemoine-Goumard; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; G. M. Madejski; A. Makeev; W. Max-Moerbeck; M. N. Mazziotta; W. McConville; J. E. McEnery; C. Meurer; P. F. Michelson; W. Mitthumsiri; T. Mizuno; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; P. L. Nolan; J. P. Norris; E. Nuss; T. Ohsugi; N. Omodei; E. Orlando; J. F. Ormes; D. Paneque; J. H. Panetta; D. Parent; V. Pavlidou; T. J. Pearson; M. Pepe; M. Pesce-Rollins; F. Piron; T. A. Porter; S. Rainò; R. Rando; M. Razzano; A. Readhead; A. Reimer; O. Reimer; T. Reposeur; J. L. Richards; S. Ritz; A. Y. Rodriguez; R. W. Romani; F. Ryde; H. F.-W. Sadrozinski; R. Sambruna; D. Sanchez; A. Sander; P. M. Saz Parkinson; J. D. Scargle; T. L. Schalk; C. Sgrò; D. A. Smith; G. Spandre; P. Spinelli; J.-L. Starck; M. Stevenson; M. S. Strickman; D. J. Suson; G. Tagliaferri; H. Takahashi; T. Tanaka; J. G. Thayer; D. J. Thompson; L. Tibaldo; O. Tibolla; D. F. Torres; G. Tosti; A. Tramacere; Y. Uchiyama; T. L. Usher; N. Vilchez; V. Vitale; A. P. Waite; B. L. Winer; K. S. Wood; T. Ylinen; J. A. Zensus; M. Ziegler; G. Ghisellini; L. Maraschi; F. Tavecchio; E. Angelakis

    2009-01-01

    We report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope of high-energy gamma-ray emission from the peculiar quasar PMN J0948+0022 (z = 0.5846). The optical spectrum of this object exhibits rather narrow Hbeta (FWHM(Hbeta) ~1500 km s-1), weak forbidden lines, and is therefore classified as a narrow-line type I quasar. This class of objects

  3. A new look at the isotropy of narrow line emission in extragalactic radio sources

    E-print Network

    Chris Simpson

    1998-03-03

    We undertake a quantitative investigation, using Monte Carlo simulations, of the amount by which quasars are expected to exceed radio galaxies in optical luminosity in the context of the `receding torus' model. We compare these simulations with the known behaviour of the [O III] 5007 and [O II] 3727 emission lines and conclude that [O III] is the better indicator of the strength of the underlying non-stellar continuum.

  4. First results from the FPGA/NIOS Adaptive FIR Filter Using Linear Prediction Implemented in the AERA Radio Stations to Reduce Narrow Band RFI for Radio Detection of Cosmic Rays

    E-print Network

    Zbigniew Szadkowski; D. G?as; C. Timmermans; T. Wijnen for the Pierre Auger Collaboration

    2014-06-03

    The FPGA/NIOS FIR filter based on linear prediction (LP) to suppress radio frequency interference (RFI) has been installed in several radio stations in the Auger Engineering Radio Array (AERA) experiment. AERA observes coherent radio emission from extensive air showers induced by ultra-high-energy cosmic rays to make a detailed study of the development of the electromagnetic part of air showers. Radio signals provide complementary information to that obtained from Auger surface detectors, which are predominantly sensitive to the particle content of an air shower at the surface. The radio signals from air showers are caused by the coherent emission due to geomagnetic and charge-excess processes. These emissions can be observed in the frequency band between 10 - 100 MHz. However, this frequency range is significantly contaminated by narrow-band RFI and other human-made distortions. A FIR filter implemented in the FPGA logic segment of the front-end electronics of a radio sensor significantly improves the signal-to-noise ratio. In this paper we present first results of the efficiency of the adaptive LP FIR filter, deployed in real AERA station on pampas, with a comparison to the currently used IIR notch filter with constant coefficients. The laboratory tests confirms the stability of the filter. Using constant LP coefficients the suppression efficiency remains the same for hours, which corresponds to more than $\\bf 10^{12}$ clock cycles. We compared in real conditions several variants of the LP FIR filter with various lengths and various coefficients widths (due to fixed-point representations in the FPGA logic) with the aim to minimize the power consumption for the radio station while keeping sufficient accuracy for noise reduction.

  5. THE SOFT X-RAY AND NARROW-LINE EMISSION OF Mrk 573 ON KILOPARSEC SCALES

    SciTech Connect

    Gonzalez-Martin, O. [IESL, Foundation for Research and Technology, 71110 Heraklion, Crete (Greece); Acosta-Pulido, J. A.; Garcia, A. M. Perez [Instituto de Astrofisica de Canarias (IAC), C/VIa Lactea, s/n E-38205, La Laguna, Tenerife (Spain); Ramos Almeida, C., E-mail: omaira@physics.uoc.g, E-mail: jap@iac.e, E-mail: apg@iac.e, E-mail: C.Ramos@sheffield.ac.u [Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH (United Kingdom)

    2010-11-10

    We present a study of the circumnuclear region of the nearby Seyfert galaxy Mrk 573 using Chandra, XMM-Newton, and Hubble Space Telescope (HST) data. We have studied the morphology of the soft (<2 keV) X-rays comparing it with the [O III] and H{alpha} HST images. The soft X-ray emission is resolved into a complex extended region. The X-ray morphology shows a biconical region extending up to 12 arcsec (4 kpc) in projection from the nucleus. A strong correlation between the X-rays and the highly ionized gas seen in the [O III]{lambda}5007 A image is reported. Moreover, we have studied the line intensities detected with the XMM-Newton Reflection Grating Spectrometer (RGS) and used them to fit the low-resolution EPIC/XMM-Newton and ACIS/Chandra spectra. The RGS/XMM-Newton spectrum is dominated by emission lines of C VI, O VII, O VIII, Fe XVII, and Ne IX, among other highly ionized species. A good fit is obtained using these emission lines found in the RGS/XMM-Newton spectrum as a template for Chandra spectra of the nucleus and extended emission, coincident with the cone-like structures seen in the [O III]/H{alpha} map. The photoionization model Cloudy provides a reasonable fit for both the nuclear region and the cone-like structures showing that the dominant excitation mechanism is photoionization. For the nucleus the emission is modeled using two phases: a high ionization [log (U) = 1.23] and a low ionization [log (U) = 0.13]. For the high-ionization phase the transmitted and reflected components are in a 1:2 ratio, whereas for the low ionization the reflected component dominates. For the extended emission, we successfully reproduced the emission with two phases. The first phase shows a higher ionization parameter for the northwest (log (U) = 0.9) than for the southeast cone (log (U) = 0.3). Moreover, this phase is transmission dominated for the southeast cone and reflection dominated for the northwest cone. The second phase shows a low-ionization parameter (log (U) = -3) and is rather uniform for northwest and southeast cones and equally distributed in reflection and transmission components. In addition, we have also derived the optical/infrared spectral energy distribution (SED) of the nucleus from high spatial resolution images of Mrk 573. The nuclear optical/infrared SED of the nucleus has been modeled by a clumpy torus model. The torus bolometric luminosity agrees very well with the active galactic nucleus (AGN) luminosity inferred from the observed hard X-ray spectrum. The optical depth along the line of sight expected from the torus modeling indicates a high neutral hydrogen column density in agreement with the classification of the nucleus of Mrk 573 as a Compton-thick AGN.

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

    SciTech Connect

    Gong, Yan-Xiao [Department of Physics, Southeast University, Nanjing 211189 (China); National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093 (China); Xie, Zhen-Da; Xu, Ping; Zhu, Shi-Ning [National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093 (China); Yu, Xiao-Qiang; Xue, Peng [Department of Physics, Southeast University, Nanjing 211189 (China)

    2011-11-15

    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 nondegenerate cases, facilitating applications of the entangled photons.

  7. An optimization of the FPGA/NIOS adaptive FIR filter using linear prediction to reduce narrow band RFI for the next generation ground-based ultra-high energy cosmic-ray experiment

    NASA Astrophysics Data System (ADS)

    Szadkowski, Zbigniew; Fraenkel, E. D.; Glas, Dariusz; Legumina, Remigiusz

    2013-12-01

    The electromagnetic part of an extensive air shower developing in the atmosphere provides significant information complementary to that obtained by water Cherenkov detectors which are predominantly sensitive to the muonic content of an air shower at ground. The emissions can be observed in the frequency band between 10 and 100 MHz. However, this frequency range is significantly contaminated by narrow-band RFI and other human-made distortions. The Auger Engineering Radio Array currently suppresses the RFI by multiple time-to-frequency domain conversions using an FFT procedure as well as by a set of manually chosen IIR notch filters in the time-domain. An alternative approach developed in this paper is an adaptive FIR filter based on linear prediction (LP). The coefficients for the linear predictor are dynamically refreshed and calculated in the virtual NIOS processor. The radio detector is an autonomous system installed on the Argentinean pampas and supplied from a solar panel. Powerful calculation capacity inside the FPGA is a factor. Power consumption versus the degree of effectiveness of the calculation inside the FPGA is a figure of merit to be minimized. Results show that the RFI contamination can be significantly suppressed by the LP FIR filter for 64 or less stages.

  8. Phonon Band Filling and Photon Emission by Phonons

    Microsoft Academic Search

    R. Brazis; R. Raguotis

    2001-01-01

    Phonon generation by electrons is supplied in n-type Si crystals in electric fields E=100 kV\\/cm at the lattice temperature of 80 K employing the ensemble Monte Carlo technique. Electron transfer between equivalent energy valleys is accounted for the g-type- and f-type phonon absorption and emission. Acoustic phonons are accounted for the quasi-elastic scattering of electrons within the energy valleys. Excess

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

    PubMed Central

    Chen, Ou; Zhao, Jing; Chauhan, Vikash P.; Cui, Jian; Wong, Cliff; Harris, Daniel K.; Wei, He; Han, Hee-Sun; Fukumura, Dai; Jain, Rakesh K.; Bawendi, Moungi G.

    2013-01-01

    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 requirements for the successful use of colloidal quantum dots (QDs) in nearly all optical applications. However, synthesizing samples that simultaneously meet all these four criteria has proven challenging. Here, we report the synthesis of such high-quality CdSe/CdS core/shell QDs in an optimized process which maintains a slow growth rate of the shell through the use of octanethiol and cadmium oleate as precursors. In contrast with previous observations, single-QD blinking is significantly suppressed with only a relatively thin shell. In addition, we demonstrate the elimination of the ensemble luminescence photodarkening that is an intrinsic consequence of QD blinking statistical aging. Furthermore, the small size and high photoluminescence quantum yields of these novel QDs render them superior in vivo imaging agents compared to conventional QDs. We anticipate that this new generation of QDs will also result in significant improvement in the performance of QDs in other applications such as solid-state lighting and illumination. PMID:23377294

  10. 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.

  11. Masking of low-frequency signals by high-frequency, high-level narrow bands of noisea

    PubMed Central

    Patra, Harisadhan; Roup, Christina M.; Feth, Lawrence L.

    2011-01-01

    Low-frequency masking by intense high-frequency noise bands, referred to as remote masking (RM), was the first evidence to challenge energy-detection models of signal detection. Its underlying mechanisms remain unknown. RM was measured in five normal-hearing young-adults at 250, 350, 500, and 700 Hz using equal-power, spectrally matched random-phase noise (RPN) and low-noise noise (LNN) narrowband maskers. RM was also measured using equal-power, two-tone complex (TC2) and eight-tone complex (TC8). Maskers were centered at 3000 Hz with one or two equivalent rectangular bandwidths (ERBs). Masker levels varied from 80 to 95 dB sound pressure level in 5 dB steps. LNN produced negligible masking for all conditions. An increase in bandwidth in RPN yielded greater masking over a wider frequency region. Masking for TC2 was limited to 350 and 700 Hz for one ERB but shifted to only 700 Hz for two ERBs. A spread of masking to 500 and 700 Hz was observed for TC8 when the bandwidth was increased from one to two ERBs. Results suggest that high-frequency noise bands at high levels could generate significant low-frequency masking. It is possible that listeners experience significant RM due to the amplification of various competing noises that might have significant implications for speech perception in noise. PMID:21361445

  12. 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.

  13. Selective and reversible control of a chemical reaction with narrow-band infrared radiation: HXeCC radical in solid xenon

    SciTech Connect

    Khriachtchev, Leonid; Tanskanen, Hanna; Raesaenen, Markku [Laboratory of Physical Chemistry, University of Helsinki, P. O. Box 55, FIN-00014, Helsinki (Finland)

    2006-05-14

    The light-induced H+XeC{sub 2}{r_reversible}HXeCC reaction is studied in solid Xe, and the full optical control of this reaction is demonstrated. By narrow-band excitation in the IR spectral region, HXeCC radicals can be decomposed to a local metastable configuration and then selectively recovered by resonant excitation of the XeC{sub 2} vibrations. The novel recovery process is explained by short-range mobility of the reagents promoted by vibrational energy redistribution near the absorbing XeC{sub 2} molecule. This means that a chemical reaction can be selectively promoted in a desired place where the chosen absorber locates. The obtained results make a strong case of solid-state reactive vibrational excitation spectroscopy of weak radiationless transitions.

  14. Selective and reversible control of a chemical reaction with narrow-band infrared radiation: HXeCC radical in solid xenon.

    PubMed

    Khriachtchev, Leonid; Tanskanen, Hanna; Räsänen, Markku

    2006-05-14

    The light-induced H + XeC2 <--> HXeCC reaction is studied in solid Xe, and the full optical control of this reaction is demonstrated. By narrow-band excitation in the IR spectral region, HXeCC radicals can be decomposed to a local metastable configuration and then selectively recovered by resonant excitation of the XeC2 vibrations. The novel recovery process is explained by short-range mobility of the reagents promoted by vibrational energy redistribution near the absorbing XeC2 molecule. This means that a chemical reaction can be selectively promoted in a desired place where the chosen absorber locates. The obtained results make a strong case of solid-state reactive vibrational excitation spectroscopy of weak radiationless transitions. PMID:16709089

  15. The impact of extra-column band broadening on the chromatographic efficiency of 5 cm long narrow-bore very efficient columns.

    PubMed

    Fekete, Szabolcs; Fekete, Jeno

    2011-08-01

    Small columns packed with core-shell and sub-2 ?m totally porous particles and monolith columns are very popular to conduct fast and efficient chromatographic separations. In order to carry out fast separations, short (2-5 cm) and narrow-bore (2-2.1 mm) columns are used to decrease the analyte retention volume. Beside the column efficiency, another significant issue is the extra-column band-spreading. The extra-column dispersion of a given LC system can dramatically decrease the performance of a small very efficient column. The aim of this study was to compare the extra-column peak variance contribution of several commercially available LC systems. The efficiency loss of three different type 5 cm long narrow bore, very efficient columns (monolith, sub-2 ?m fully porous and sub-2 ?m core-shell packing) as a function of extra-column peak variance, and as a function of flow rate and also kinetic plots (analysis time versus apparent column efficiency) are presented. PMID:21726868

  16. 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, ...

  17. Broad-band visible emission from UV-exposed TPD solution

    Microsoft Academic Search

    M. P. Joshi; S Raj Mohan; S. K. Tiwari; T. S. Dhami; T. Shripathi; U. P. Deshpande; M. K. Singh; H. Ghosh

    Strong broad band visible emission from N-N'- diphenyl-N-N'-bis(3-methylphenyl)-1-1- biphenyl-4,4'- diamine (TPD) is reported when solution of TPD (in halomethane solvents like chloroform or dichloromethane) is exposed to UV light. Emission color changes from originally blue to green with exposure. Uv-visible absorption, FTIR and XPS studies of photoproduct suggest photodegradation of TPD. With UV exposure the photolysis of chloroform first oxidizes

  18. Band emission of inert gases pumped by electron beams

    SciTech Connect

    Bunkin, F.V.; Derzhiev, V.I.; Mesiats, G.A.; Skakun, V.S.; Tarasenko, V.F.

    1986-11-01

    The 220-600-nm spectra of He, Ne, Ar, Kr, and Xe at pressures 0.5-3 atm are observed experimentally on pumping with either (1) 50-ns (FWHM) 40-A/sq cm pulses of an electron beam of cross section 2 x 42 cm at repetition rate f = 1/30 Hz or (2) 3-ns 500-A/sq cm pulses of an electron beam of diameter 1 cm at f = 6 Hz. The results are presented graphically and characterized in detail. Strong broadband emission is observed in all of the gases except He and attributed to transitions between excited states of the metastable R2(+) molecular ions. It is suggested that such ions could be formed in collisions between neutrals and metastable R(+) atoms, the latter arising from recombination of R(2+). 7 references.

  19. Nonlinear optical effects in spontaneous and stimulated emission from excited two-band intrinsic semiconductor

    Microsoft Academic Search

    V. Cheltsov

    2005-01-01

    The basic results of theoretical nonperturbative analysis of spontaneous and stimulated emission from two-band excited intrinsic semiconductor interacting with a single mode of radiation field in a lossless micro-cavity are presented. The self-consistent dynamics of the coupled system ''semiconductor + single mode radiation field\\

  20. THE EFFECT OF DEW ON THE MICROWAVE EMISSION OF MAIZE AT L-BAND

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dew has the net effect of decreasing the brightness temperature of maize at L-band. Scattering is enhanced more than emission. This effect occurs at both polarizations, but vertically-polarized brightness is affected more than horizontally-polarized brightness. As more water condenses on the cano...

  1. A simple parameterization of the L-band microwave emission from rough agricultural soils

    Microsoft Academic Search

    Jean-Pierre Wigneron; Laurent Laguerre; Yann H. Kerr

    2001-01-01

    A simple model for simulating the L-band microwave emission from bare soils is developed. The model is calibrated on a large set of measurements obtained during a three-month period over seven plots covering a wide range of surface roughness (representing the total range which can be expected on agricultural fields), soil moisture, and temperature conditions. The approach is based on

  2. Simulating L-band emission of forests in view of future satellite applications

    Microsoft Academic Search

    Paolo Ferrazzoli; Leila Guerriero; Jean-Pierre Wigneron

    2002-01-01

    The microwave model developed at the Tor Vergata University is used to simulate the emissivity of forests, in order to study the performance of an L-band spaceborne radiometer, similar to that carried by the Soil Moisture Ocean Salinity mission. The model is first validated, and the importance of a correct vegetation growth parametrization in the modeling procedure is pointed out.

  3. Supporting Information High Quantum Efficiency of Band-Edge Emission from

    E-print Network

    Yang, Peidong

    were normalized to = 470nm. #12;3 Figure S3. Calculation of External Quantum Efficiency (EQE). EQE1 Supporting Information High Quantum Efficiency of Band-Edge Emission from ZnO Nanowires Daniel J efficiency (IQE) measurement of single ZnO nanowires. A) Diagram of IQE experimental setup. B) PL spectra

  4. Aromatic emission bands from the HII region ahead the Horsehead Nebula

    Microsoft Academic Search

    M. Compiègne; A. Abergel; L. Verstraete; W. T. Reach; E. Habart; J. D. Smith; F. Boulanger; C. Joblin

    2009-01-01

    We present a study of Aromatic Infrared Band (AIBs) emission in the IC434 HII region ahead the Horsehead nebula as well as in the associated photodissociation region (PDR). AIBs are detected in the HII region and the correlation of the 11.3 mum AIB with ionised gas lines shows that PAHs must be located in the ionised gas. The survival of

  5. Spontaneous emission of Bloch oscillation radiation from a single energy band

    Microsoft Academic Search

    V. N. Sokolov; L. Zhou; G. J. Iafrate; J. B. Krieger

    2006-01-01

    A theory for the spontaneous emission of radiation for a Bloch electron traversing a single energy band under the influence of a constant external electric field is presented. The constant external electric field is described in the vector potential gauge. The quantum radiation field is described by the free space quantized electromagnetic field in the Coulomb gauge. The instantaneous eigenstates

  6. Novel fluorescent probe for low density lipoprotein, based on the enhancement of Europium emission band

    NASA Astrophysics Data System (ADS)

    Courrol, L. C.; Monteiro, A. M.; Silva, F. R. O.; Gomes, L.; Vieira, N. D., Jr.; Gidlund, M. A.; Figueiredo Neto, A. M.

    2007-05-01

    We report here the observation of the enhancement of Europium-tetracycline complex emission in Low Density Lipoprotein (LDL) solutions. Europium emission band of tetracycline solution containing Europium (III) chloride hexahydrate was tested to obtain effective enhancement in the presence of native LDL and oxidized LDL. Europium emission lifetime in the presence of lipoproteins was measured, resulting in a simple method to measure the lipoproteins quantity in an aqueous solution at physiological pH. This method shows that the complex can be used as a sensor to determine the different states of native and oxidized LDL in biological fluids.

  7. Detecting Long-Duration Narrow-Band Gravitational Wave Transients Associated with Soft Gamma Repeater Quasi-Periodic Oscillations

    E-print Network

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

    2013-01-01

    We have performed an in-depth concept study of a gravitational wave data analysis method which targets repeated long quasi-monochromatic transients (triggers) from cosmic sources. The algorithm concept can be applied to multi-trigger 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 quasi-periodic oscillations (QPOs) observed in the X-ray lightcurve tails of soft gamma repeater flares might be an interesting endeavour 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 multi-trigger based data analysis approach by using O(100 s) long stretches of mock data in coincidence with the times of observed QPOs, and by using the known sky location of the source. We analytical...

  8. High resolution emission Fourier transform infrared spectra of the 4p-5s and 5p-6s bands of ArH

    NASA Astrophysics Data System (ADS)

    Baskakov, O. I.; Civiš, S.; Kawaguchi, K.

    2005-03-01

    In the 2500-8500cm-1 region several strong emission bands of ArH40 were observed by Fourier transform spectroscopy through a dc glow discharge in a mixture of argon and hydrogen. Rotational-electronic transitions of the two previously unstudied 4p-5s and 5p-6s,v=0-0, bands of ArH40 were measured and assigned in the 6060 and 3770cm-1 regions, respectively. A simultaneous fit of the emission transitions of the 4p-5s and 5p-6s bands and an extended set of transitions of the 6s-4p band observed by Dabrowski, Tokaryk, and Watson [J. Mol. Spectrosc. 189, 95 (1998)] and remeasured in the present work yielded consistent values of the spectroscopic parameters of the electronic states under investigation. In the branch of the 4p-5s band with transitions of type Qf3eQ we observed a narrowing in the linewidths with increasing rotational quantum number N. The rotational dependence of the linewidth is caused by predissociation of the 5s state by the repulsive ground 4s state through homogeneous coupling and changes in overlap integrals of the vibrational wave functions with the rotational level. Analysis was based on the Fermi's golden rule approximation model. In the 4p-5s band region a vibrational sequence ofv'-v?=1-1, 2-2, and 3-3 were recorded and a number of transitions belonging to the strongest Qf3eQ form branch of the 1-1 band were analyzed.

  9. Experimental verification of directional liquid surface wave emission at band edge frequencies

    NASA Astrophysics Data System (ADS)

    Wang, Zhenyu; Zhang, Pei; Zhang, Yongqiang; Nie, Xiaofei

    2013-12-01

    Directional liquid surface wave emission at band edge frequencies is an interesting physical phenomenon and has already been studied in theoretical research. There has been no experimental validation of it to date, however. This paper has as its subject the experimental investigation of the emission effect when a point source is placed inside a finite square array of rigid cylinders standing vertically in liquid. Both the wave patterns and spatial intensities are obtained by experiment and compared with simulated results calculated by using the finite element method. We can see from this comparison that the two results correspond closely both at lower and upper band edge frequency. Obvious directional wave emission along a desired direction is observed in the source structures, confirming previous theoretical predictions. In the future, this method could serve as a directional liquid wave source in applications used in hydraulic and ocean engineering for the concentration of wave energy.

  10. 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.

  11. Measurement of spontaneous emission from a two-dimensional photonic band gap defined microcavity at near-infrared wavelengths

    Microsoft Academic Search

    R. K. Lee; O. J. Painter; B. D'Urso; A. Scherer; A. Yariv

    1999-01-01

    An active, photonic band gap-based microcavity emitter in the near infrared is demonstrated. We present direct measurement of the spontaneous emission power and spectrum from a microcavity formed using a two-dimensional photonic band gap structure in a half wavelength thick slab waveguide. The appearance of cavity resonance peaks in the spectrum correspond to the photonic band gap energy. For detuned

  12. Measurement of spontaneous emission from a two-dimensional photonic band gap defined microcavity at near-infrared wavelengths

    Microsoft Academic Search

    R. K. Lee; O. J. Painter; B. D'Urso; A. Scherer; A. Yariv

    An active, photonic band gap-based microcavity emitter in the near infrared is demonstrated. We present direct measurement of the spontaneous emission power and spectrum from a microcavity formed using a two-dimensional photonic band gap structure in a half wavelength thick slab waveguide. The appearance of cavity resonance peaks in the spectrum correspond to the photonic band gap energy. For detuned

  13. The measurement of the lateralization of narrow bands of noise using an acoustic pointing paradigm: the effect of sound-pressure level.

    PubMed

    Simon, H J; Collins, C C; Jampolsky, A; Morledge, D E; Yu, J

    1994-03-01

    The effects of varying interaural time delay (ITD) and interaural intensity difference (IID) were measured in normal-hearing subjects as a function of eleven frequencies and at sound-pressure levels (SPL) from 60 to 90 dB SPL and at 25-dB sensation level. Using an "acoustic" pointing paradigm, the IID of a 500-Hz narrow-band (100 Hz) noise (the "pointer") was varied by the subject to coincide with that of a "target" ITD stimulus. ITDs of 0, +/- 200, and +/- 400 microseconds were obtained through total waveform delays of narrow-band noise (NBN), including envelope and fine structure. The results of this experiment confirm the traditional view of binaural hearing for like stimuli: There is little perceived displacement away from 0 IID at frequencies of 1250 Hz and above. In the low frequencies, subjects required IIDs greater than the expected 10 dB to perceive a fully lateralized image, and they varied in the maximum value of IID that they required, regardless of frequency. Our subjects did not always perceive the intracranial locations of ITD targets symmetrically: When the signal was delayed to one ear, the resultant matching IID was often different in magnitude than for the same ITD target delayed to the opposite ear for the identical frequency. The results of two subjects suggested that people with asymmetric normal hearing have adapted to their asymmetry for lateralization tasks: The subjects were found to lateralize toward the ear with the greater SPL stimulus, regardless of the ear to which the signal was delayed, when signals of equal SL were presented, and toward the leading ear when signals of equal SPL were presented (unequal SL). Increasing the presentation levels above 60 dB SPL had an effect on the perception of high-frequency ITD targets: As the intensity level increased, the slopes of the IID versus ITD functions increased indicating better discrimination of ITD. This study is in agreement with other studies in providing strong evidence of individual differences in lateralization experiments. These individual differences might be attributable to differential sensitivity to ambiguous time stimulus cues, differential task sensitivity, age effects, threshold asymmetries, or criterion variability. PMID:8176057

  14. 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. [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Van Boekel, R.; Henning, Th. [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Madhusudhan, N. [Department of Physics and Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Chen, G., E-mail: wangw@nao.cas.cn [Purple Mountain Observatory, Chinese Academy of Sciences, West Beijing Road, Nanjing 210008 (China)

    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.

  15. Observation of an excimer emission band of the ArOD van der Waals molecule

    NASA Astrophysics Data System (ADS)

    Lemaire, J. L.; Tchang-Brillet, W.-Ü. L.; Shafizadeh, N.; Rostas, F.; Rostas, J.

    1989-12-01

    An excimer emission band attributed to a transition from the first excited state to the ground state of the van der Waals Ar(OD) molecule has been observed in experiments where D2O was dissociated in presence of rare gases by two photons of a quadrupled YAG laser (266 nm). KrOD has also been observed in the same experiments. The ArOD excimer band comprises three main peaks at 313.9, 315.1, and 316.0 nm as well as several minor ones nearer to the main OH (A2 ?+,v=0-X2 ?,v=0) emission band. The emission profile is realistically simulated by a one dimension model using recently published potentials for the excited state and modeling the ground state by that of the ArF X 2 ?+ state. This result tends to demonstrate that the ground state geometry of Ar(OD) involved in the transition is probably L shaped although the high intensity of the observed excimer band is not satisfactorily explained.

  16. Spatial distribution of emission in unidentified infrared bands from the Midcourse Space Experiment survey

    NASA Astrophysics Data System (ADS)

    Ghosh, S. K.; Ojha, D. K.

    2002-06-01

    The Midcourse Space Experiment (MSX) has surveyed the Galactic plane in four infrared bands between 6 and 25 mu m. Two of these bands cover several Unidentified Infrared emission Bands (UIBs). With the aim of extracting the spatial distribution of the UIB emission on a large scale, a scheme has been developed to model the MSX data with emission in the UIBs alongwith the underlying thermal continuum from the interstellar dust. In order to test this scheme, a sample of five Galactic compact H II regions (Sh-61, Sh-138, Sh-152, Sh-156, Sh-186; Zavagno & Ducci \\cite{Zavagno01}) for which imaging data in some individual UIBs is available from ISOCAM measurements, has been studied. The results of this comparative study on a small angular scale are as follows: (i) the morphological details extracted from our scheme agree very well with those from the superior ISOCAM measurements; (ii) the integrated strength of UIBs extracted from the MSX database correlates extremely well with the sum of the strengths of individual UIBs measured from ISOCAM. This tight correlation is very encouraging and promises the potential of MSX database for the study of large-scale spatial distribution of UIB emission (and the carriers of UIBs) in the entire Galactic plane.

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

    E-print Network

    Tateuchi, Ken; Motohara, Kentaro; Takahashi, Hidenori; Kato, Natsuko Mitani; 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

    2014-01-01

    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 the optical wavelength. We have carried out Pa$\\alpha$ narrow-band imaging observations of 38 nearby star-forming galaxies including 33 LIRGs listed in $IRAS$ RBGS catalog with the Atacama Near InfraRed camera (ANIR) on the University of Tokyo Atacama Observatory (TAO) 1.0 m telescope (miniTAO). Star formation rates (SFRs) estimated from the Pa$\\alpha$ fluxes, corrected for dust extinction using the Balmer Decrement Method (typically $A_V$ $\\sim$ 4.3 mag), show a good correlation with those from the bolometric infrared luminosity of $IRAS$ data within a scatter of 0.27 dex. This suggests that the correction of dust extinction for Pa$\\alpha$ flux is sufficient in our sample. We measure the physical sizes and the surface density of infrared luminosities ($\\Sigma_{L(\\mathrm{IR})}$) and $SFR$ ($\\Sigma_{SFR}$) of star-forming region for individual ga...

  18. Perceived lateral position of narrow-band noise in hearing-impaired and normal-hearing listeners under conditions of equal sensation level and sound-pressure level.

    PubMed

    Simon, H J; Aleksandrovsky, I

    1997-09-01

    The perceived lateral position of narrow-band noise (NBN) was studied in a graphic pointer task as a function of the method of compensation for interaural threshold asymmetries in hearing-impaired and normal-hearing subjects. The method of compensation consisted of equal sensation level (EqSL) or equal sound-pressure level (EqSPL) at the two ears within the same subject. The NBN signals were presented at 11 center frequencies with interaural intensity differences (IIDs) that varied from -20 to +20 dB. When equalizing by SL, the perceived lateral position is essentially linearly dependent on the degree and direction of asymmetry in asymmetric normal-hearing and hearing-impaired listeners. Equalizing by SPL shows no such dependency but produces images that are lateralized close to the midline. These results reveal that subjects may have adapted to their threshold asymmetries. These results will be discussed in terms of the fitting of binaural hearing aids. PMID:9301059

  19. The “white globe appearance” (WGA): a novel marker for a correct diagnosis of early gastric cancer by magnifying endoscopy with narrow-band imaging (M-NBI)

    PubMed Central

    Doyama, Hisashi; Yoshida, Naohiro; Tsuyama, Sho; Ota, Ryosuke; Takeda, Yasuhito; Nakanishi, Hiroyoshi; Tsuji, Kunihiro; Tominaga, Kei; Tsuji, Shigetsugu; Takemura, Kenichi; Yamada, Shinya; Katayanagi, Kazuyoshi; Kurumaya, Hiroshi; Iwashita, Akinori; Yao, Kenshi

    2015-01-01

    Background and study aims: Although magnifying endoscopy with narrow-band imaging (M-NBI) is useful for the diagnosis of gastric mucosal lesions, differentiating between early cancer (EC) and low grade adenoma (LGA) remains a challenge. During M-NBI examination, we have noted the presence of a small, white lesion with a globular shape underneath cancerous gastric epithelium, and have termed this endoscopic finding the “white globe appearance” (WGA). The aim of this study was to determine whether or not the WGA could be an endoscopic marker for distinguishing EC from LGA. Methods: We retrospectively analyzed both the M-NBI scans and resected specimens of a total of 111 gastric lesions from 95 consecutive patients. Our main outcome was a difference in the prevalence of the WGA in EC and LGA. Results: The prevalence of the WGA in EC and LGA was 21.5?% (20?/93) and 0?% (0?/18), respectively (P?=?0.039). The sensitivity, specificity, positive predictive value, and negative predictive value for differentiating between EC and LGA, according to the presence of the WGA, were 21.5, 100, 100, and 19.8?%, respectively. Conclusion: A positive WGA in a suspicious lesion on M-NBI would be an adjunct to the M-NBI diagnosis of possible EC because the specificity and positive predictive value of the WGA for differentiating between EC and LGA were extremely high. The WGA could be a novel endoscopic marker for differentiating between EC and LGA.

  20. 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

  1. Development of a L-band ocean emissivity electromagnetic model using observations from the Aquarius Radiometer

    NASA Astrophysics Data System (ADS)

    Hejazin, Y.; Jones, W.; El-Nimri, S.

    2012-12-01

    The Aquarius/SAC-D ocean salinity measurement mission was launched into polar orbit during the summer of 2011. The prime sensor is an L-band radiometer/scatterometer developed jointly by NASA Goddard Space Flight Center and the Jet Propulsion Laboratory. This paper deals with the development of an ocean emissivity model using AQ radiometer brightness temperature (Tb) observations. This model calculates the ocean surface emissivity as a function of ocean salinity, sea surface temperature, surface wind speed and direction. One unique aspect of this model is that it calculates ocean emissivity over wide ranges of Earth incidence angles (EIAs) from nadir to > 60°and ocean wind speeds from 0 m/s to > 70 m/s. This physical electromagnetic model with empirical coefficients follows the form of Stogryn [1967] that treats the ocean as a mixture of foam and clean rough water. The CFRSL ocean surface emissivity (?ocean) is modeled as a linear sum of foam (?foam) and foam-free seawater (?rough) emissivities, according to ?ocean = FF * ?foam + (1 - FF) * ?rough (1) where FF is the fractional area coverage by foam. The foam emissivity is modeled as ?foam = Q(freq, U10, EIA) (2) where Q( ) is the empirical dependence of foam emissivity on radiometer frequency, the 10-m neutral stability wind speed and EIA according to El-Nimri [2010]. Following Stogryn, the foam-free seawater emissivity (?rough) is modeled ?rough = ?smooth +??excess (3) where ?smooth = (1 - ?) is the smooth surface emissivity, ? is the Fresnel power reflection coefficient, and ??excess is the wind-induced excess emissivity, given by ??excess = G(freq, U10, WDir, EIA) (4) Where G( ) is the empirical signature of foam-free rough ocean, which depends upon the surface wind speed and wind direction. This function is determined empirically from measured AQ radiometer Tb's associated with surface wind vector from collocated NOAA GDAS numerical weather model. Ocean emissivity calculations are compared to AQ ocean surface Tb's normalized by collocated SST. Results are parametrically presented in a series of two dimensional graphs that illustrate the dependence of ocean emissivity on EIA, SST, salinity, U10 and wind direction. References: A. Stogryn, 1967, "The apparent temperature of the sea at microwave frequencies," IEEE Trans. Antennas Propag., vol. AP-15, no. 2, pp. 278-286, Mar. S. El-Nimri et al., 2010, "An improved C-band ocean surface emissivity model at hurricane force wind speeds over a wide range of earth incidence angles," IEEE Geosci. Rem. Sens. Letters, vol. 7, NO. 4, October.

  2. Photo field-emission spectroscopy of optical transitions in the band structure of rhenium

    NASA Astrophysics Data System (ADS)

    Rado?, T.; Kleint, Ch.

    1984-09-01

    Photo field-emission (PFE) current-voltage curves of clean and barium covered rhenium have been determined with an argon ion laser and phase sensitive detection. Field strength and work function were obtained from Fowler-Nordheim plots of the field emission currents. According to a two-step PFE model the knees of the PFE characteristics are ascribed to optical transitions in the Brillouin zone near the Fermi level. Most of the observed excitations could be correlated to direct transitions in the rhenium band structure as calculated by Mattheiss including spin-orbit coupling.

  3. Studies of Breakdown in High Gradient X-Band Accelerator Structures Using Acoustic Emission

    SciTech Connect

    Frisch, Josef C

    2002-08-23

    X-band accelerator structures meeting the Next Linear Collider (NLC) design requirements have been found to suffer damage due to RF breakdown when processed to high gradients. Improved understanding of these breakdown events is desirable for the development of structure designs, fabrication procedures, and processing techniques that minimize structure damage [1]. Acoustic emission sensors attached to an accelerator structure can detect both nominal and breakdown RF pulses [2]. Using an array of acoustic sensors, we have been able to pinpoint both the cell and azimuth location of individual breakdown events. This allows studies of breakdown time and position sequences so that underlying causes can be determined. The technique provided a significant advance in studies of breakdown in the structure input coupler. In this paper we present acoustic emission sensor data and analysis from the breakdown studies in several x-band accelerator structures.

  4. BroadBand Spectrum of dMe Star Radio Emission M Gudel and A. O. Benz

    E-print Network

    Guedel, Manuel

    magnetic field 1. Introduction Nonflaring microwave emission of late type red dwarf stars has become emission of UV Ceti was detected at 20cm at comparable flux levels (Fisher and Gibson, 1981; KunduBroad­Band Spectrum of dMe Star Radio Emission M G¨udel and A. O. Benz Institute of Astronomy, ETH

  5. 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.

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

    SciTech Connect

    Kadashchuk, A. [IMEC v.z.w., SOLO-PME, Kapeldreef 75, B-3001 Leuven (Belgium); Institute of Physics, National Academy of Science of Ukraine, Kiev 03028 (Ukraine); Schols, S. [IMEC v.z.w., SOLO-PME, Kapeldreef 75, B-3001 Leuven (Belgium); Department of Electrical Engineering, Katholieke Universiteit Leuven, B-3001 Leuven (Belgium); Heremans, P. [IMEC v.z.w., SOLO-PME, Kapeldreef 75, B-3001 Leuven (Belgium); Skryshevski, Yu.; Piryatinski, Yu. [Institute of Physics, National Academy of Science of Ukraine, Kiev 03028 (Ukraine); Beinik, I.; Teichert, C. [Institute of Physics, University of Leoben, A-8700 Leoben (Austria); Hernandez-Sosa, G.; Sitter, H. [Institute of Semiconductor and Solid State Physics, University of Linz, A-4040 Linz (Austria); Andreev, A. [Nanoindent Technologies AG, A-4020 Linz (Austria); Frank, P.; Winkler, A. [Graz University of Technology, A-8010 Graz (Austria)

    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.

  7. Acoustic emission frequency discrimination

    NASA Technical Reports Server (NTRS)

    Sugg, Frank E. (inventor); Graham, Lloyd J. (inventor)

    1988-01-01

    In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.

  8. Role of narrow-band imaging and high-definition television in the surveillance of head and neck squamous cell cancer after chemo- and/or radiotherapy.

    PubMed

    Piazza, Cesare; Cocco, Daniela; De Benedetto, Luigi; Bon, Francesca Del; Nicolai, Piero; Peretti, Giorgio

    2010-09-01

    Narrow-band imaging (NBI) is an endoscopic technique enhancing mucosal vasculature and better identifying superficial carcinomas due to their neo-angiogenic pattern. NBI accuracy is increased by combination with a high-definition television (HDTV) camera. The aim of this report was to evaluate the diagnostic improvement of NBI +/- HDTV in the evaluation of head and neck squamous cell cancer (HNSCC) previously treated by chemo-radiotherapy (CHT-RT) or RT. A total of 390 patients affected by HNSCC were prospectively evaluated by NBI and white light (WL) endoscopy +/- HDTV between April 2007 and April 2009 at a single academic institution. Among them, we focused on 59 (15%) patients who received CHT-RT or RT as part of their treatment. Of 59 patients, 13 (22%) showed adjunctive preoperative NBI findings when compared to the standard WL examination. These findings were always confirmed by intraoperative HDTV NBI, while only eight (62%) were visible with HDTV WL. Of 13 lesions, 12 received histopathologic confirmation (from carcinoma in situ to invasive carcinoma). The sensitivity of flexible NBI, HDTV WL, and HDTV NBI was 100, 66 and 100%, respectively. The specificity was 98, 100, and 98%. The positive predictive value was 92, 100, and 92%. The negative predictive value was 100, 94, and 100%. The accuracy was 98, 91, and 98%. NBI +/- HDTV after CHT-RT or RT was of value in detecting tumor persistence (n = 2), early recurrences (n = 6), and metachronous tumors (n = 4). By contrast, only 1 of 59 (2%) patients was found to be false positive. PMID:20352239

  9. 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

  10. Radio wave emissions in the v.l.f.-band observed near the auroral zone--I occurrence of emissions during disturbances

    Microsoft Academic Search

    Leiv Harang; Reidulv Larsen

    1965-01-01

    Very low frequency emissions in the 8 kc\\/s-band have been recorded at the Auroral Observatory, Tromsö and bursts of enhanced emissions have been compared with geomagnetic records, absorption effects recorded on a riometer and appearance of aurorae. It is shown that bursts of enhanced radiations in the 8 kc\\/s-band appear regularly during disturbed conditions near the auroral zone, the energy

  11. 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

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

    SciTech Connect

    Zhou, George; Bayliss, Daniel D. R. [Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd, Weston Creek, ACT 2611 (Australia); Kedziora-Chudczer, Lucyna; Bailey, Jeremy, E-mail: george@mso.anu.edu.au [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia)

    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.

  13. Study of instrument temperature effect on MODIS thermal emissive band responses

    NASA Astrophysics Data System (ADS)

    Chang, Tiejun; Xiong, Xiaoxiong

    2010-09-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) has 16 thermal emissive bands (TEB) over a spectral range from mid-wave infrared (MWIR) to long-wave infrared (LWIR), using photovoltaic (PV) HgCdTe detectors for bands 20-25 and 27-30 with wavelengths from 3.75?m to 9.73?m and photoconductive (PC) HgCdTe detectors for bands 31-36 with wavelengths from 11.0?m to 14.2?m. A total of 160 individual detectors, 10 per band, are distributed on the short- and mid-wave (SMIR) and LWIR cold focal-plane assemblies (CFPA) with temperature controlled at 83K. The instrument temperature affects the detector response and this effect varies with the detector type. Detector responses from on-orbit calibration and pre-launch measurements have been examined to characterize this effect. Results from this analysis show that, for the PV detectors on the SMIR CFPA, the detector responses (gains) increase with instrument temperature whereas the PC detector responses decrease with the instrument temperature. The calibration impact due to on-orbit changes in instrument temperatures is examined. On-orbit detector offset and nonlinear response characterization obtained from the on-boar blackbody (BB) warm-up and cool-down (WUCD) cycle is discussed. This investigation was performed for both Terra MODIS and Aqua MODIS.

  14. Some experimental parameters for the red-emission band of Egyptian muldan

    NASA Astrophysics Data System (ADS)

    Soliman, C.; Hussein, M. A.

    2004-04-01

    Thermoluminescence (TL) of the red-emission band obtained from natural muldan feldspar has shown two main peaks at around 160 and 270 degreesC, with thermal activation energies of 0.33 and 1.05 eV, respectively. The laboratory-induced TL peaks at 140 degreesC, 190 degreesC, 285 degreesC and 365 degreesC have thermal activation energies of 0.27, 0.45, 1.14 and 1.22 eV, respectively. The TL sensitivity of this band was enhanced to similar to10 times the original value when muldan was subject to pre-heating treatment at 1000 degreesC for 2 h. The TL fading effect was explained by tunneling recombination. The disordered aliquots showed no fading when post-irradiation annealed at 100 degreesC.

  15. X-ray emission spectra and valence band structure of the 3d transition metal oxides

    Microsoft Academic Search

    V. R. Galakhov; S. M. Butorin; E. Z. Kurmaev; M. A. Korotin

    1991-01-01

    X-ray emission oxygen Kalpha and 3d transition metal Lalpha spectra for MnO, FeO, CoO, NiO, and CuO have been compared in the same energy scale by using Me 2p and O 1s binding energies. In the valence band of CuO the so-called d-p resonance between Cu 3d and O 2p states was observed. The 3d metal Lalpha-spectra for these oxides

  16. 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.

  17. The ground-based H, K, and L-band absolute emission spectra of HD 209458b

    E-print Network

    Zellem, Robert T; Deroo, Pieter; Swain, Mark R; Waldmann, Ingo P

    2014-01-01

    Here we explore the capabilities of NASA's 3.0 meter Infrared Telescope Facility (IRTF) and SpeX spectrometer and the 5.08 meter 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$_{4}$ $\

  18. Deep Narrow-Band Imaging of M87: a Close Look at the Disk of Ionized Gas Fueling a Massive Black Hole

    NASA Astrophysics Data System (ADS)

    Ford, Holland

    1995-07-01

    M87 provides a unique example of a 100 pc scale disk of ionized gasfueling a massive black hole (Ford et al. 1994, Harms et al. 1994).The disk shows tantalizing evidence for spiral structure and a possibleconnection to large scale, wrapped filaments. Sparks, Ford, and Kinney(1993) used observations of dust absorption in the filaments andblueshifted velocities with respect to M87 to conclude that thefilaments are an outflow from the nucleus. If the wrapped filamentsare in fact an outflow, we are witnessing the solution to anoutstanding problem in astrophysics, that of removing angular momentumfrom a disk to allow the gas to flow onto the central massive black hole.We propose to use 6 orbits to take deep, half-pixel stepped,Halpha+[Nii] on-band images to study the morphology in the disk andfilaments. The images will be one magnitude deeper than previousimages and will reach the 0.06'' diffraction limit of the telescopeat Halpha. Our goals are to use the deep, high resolution images to:1) Investigate and understand the apparent connection between thefilaments and the disk.2) Delineate the apparent spiral structure in the disk.3) Confirm the presence of faint Halpha+[Nii] emission associated withthe jet, which could be gas which has been entrained by the jet.

  19. Single-molecule electroluminescence and photoluminescence of polyfluorene unveils the photophysics behind the green emission band

    NASA Astrophysics Data System (ADS)

    Honmou, Yoshihiro; Hirata, Shuzo; Komiyama, Hideaki; Hiyoshi, Junya; Kawauchi, Susumu; Iyoda, Tomokazu; Vacha, Martin

    2014-08-01

    Optoelectronic properties of polyfluorene, a blue light-emitting organic semiconductor, are often degraded by the presence of green emission that originates mainly from oxidation of the polymer. Here, we use single-molecule electroluminescence (EL) and photoluminescence (PL) spectroscopy on polyfluorene chains confined in vertical cylinders of a phase-separated block copolymer to spectrally resolve the green band and investigate in detail the photophysical processes responsible for its appearance. In both EL and PL, a substantial fraction of polyfluorene chains shows spectrally stable green emission which is ascribed to a keto defect. In addition, in EL, we observe a new type of vibrationally resolved spectra distributed over a wide range of frequencies and showing strong spectral dynamics. Based on quantum chemical calculations, this type is proposed to originate from charge-assisted formation and stabilization of ground-state aggregates. The results are expected to have broad implications in the fields of photophysics and material design of polyfluorene materials.

  20. Adjuvant Narrow Band UVB Improves the Efficacy of Oral Azithromycin for the Treatment of Moderate to Severe Inflammatory Facial Acne Vulgaris

    PubMed Central

    Rassai, Sima; Rafeie, Esmaeil; Ramirez-Fort, Marigdalia K; Feily, Amir

    2014-01-01

    Background: Acne vulgaris (AV) is a common inflammatory disease of the pilosebaceous unit. A variety of treatment modalities are available for the treatment of AV. Among the available options, oral azithromycin is popularly prescribed for its proven anti-inflammatory effects. Narrow band UVB (NBUVB) also has a potent anti-inflammatory action. Concomitant use of both modalities may result in a synergistic therapeutic response; however, the combined efficacy has not yet been evaluated for the treatment of inflammatory AV. Objective: The aim of this study was to compare the efficacy of oral azithromycin plus NBUVB (peak 311 nm) to oral azithromycin alone for the treatment of moderate to severe inflammatory AV. Materials and Methods: A randomized, open-label, clinical trial was conducted over 4 weeks. Subjects were randomized into two groups. Group 1 received 500 mg of oral azithromycin three times per week. Group 2 received 500 mg of oral azithromycin plus NBUVB three and two times per week, respectively. Concomitant topical or oral AV treatments were not permitted during the treatment period. Response to treatment was measured by photographic records at the primary endpoint (2 weeks) and at the end of treatment. Results: One hundred and four subjects were enrolled in the trial; 94 subjects completed the treatment period of the study. Group 2 demonstrated significant clinical improvement of the inflammatory papular lesions (88.55%) compared with group 1 (70.34%) at the end of treatment (P = 0.002). The clinical response of pustular (P = 0.562), nodular (P = 0.711) and cystic (P = 0.682) lesions did not significantly differ between the two treatment groups. Interestingly, response to treatment in group 2 had a significant anatomical predilection for the forehead (P = 0.023). There was no side-effect except erythema, which subsided within 1-2 days. Conclusion: NBUVB plus oral azithromycin is more effective than oral azithromycin alone for treating papular lesions of inflammatory AV. NBUVB is certainly a viable adjunct in acne therapy. PMID:25538435

  1. Assessment of Still and Moving Images in the Diagnosis of Gastric Lesions Using Magnifying Narrow-Band Imaging in a Prospective Multicenter Trial

    PubMed Central

    Hayashi, Tomoyuki; Doyama, Hisashi; Shirota, Yukihiro; Tsuji, Hirokazu; Marukawa, Youhei; Ohta, Hajime; Miwa, Kazuhiro; Masunaga, Takaharu; Terasaki, Shuichi; Matano, Yutaka; Tsuji, Kunihiro; Kaneko, Yoshibumi; Okada, Toshihide; Kurumaya, Hiroshi; Kaneko, Shuichi

    2014-01-01

    Objectives Magnifying narrow-band imaging (M-NBI) is more accurate than white-light imaging for diagnosing small gastric cancers. However, it is uncertain whether moving M-NBI images have additional effects in the diagnosis of gastric cancers compared with still images. Design A prospective multicenter cohort study. Methods To identify the additional benefits of moving M-NBI images by comparing the diagnostic accuracy of still images only with that of both still and moving images. Still and moving M-NBI images of 40 gastric lesions were obtained by an expert endoscopist prior to this prospective multicenter cohort study. Thirty-four endoscopists from ten different Japanese institutions participated in the prospective multicenter cohort study. Each study participant was first tested using only still M-NBI images (still image test), then tested 1 month later using both still and moving M-NBI images (moving image test). The main outcome was a difference in the diagnostic accuracy of cancerous versus noncancerous lesions between the still image test and the moving image test. Results Thirty-four endoscopists were analysed. There were no significant difference of cancerous versus noncancerous lesions between still and moving image tests in the diagnostic accuracy (59.9% versus 61.5%), sensitivity (53.4% versus 55.9%), and specificity (67.0% versus 67.6%). And there were no significant difference in the diagnostic accuracy between still and moving image tests of demarcation line (65.4% versus 65.5%), microvascular pattern (56.7% versus 56.9%), and microsurface pattern (48.1% versus 50.9%). Diagnostic accuracy showed no significant difference between the still and moving image tests in the subgroups of endoscopic findings of the lesions. Conclusions The addition of moving M-NBI images to still M-NBI images does not improve the diagnostic accuracy for gastric lesions. It is reasonable to concentrate on taking sharp still M-NBI images during endoscopic observation and use them for diagnosis. Trial registration Umin.ac.jp UMIN-CTR000008048 PMID:24988209

  2. New emission bands at high-density excitation of dense gas and liquid of helium irradiated by nitrogen ions

    Microsoft Academic Search

    Kazuie Kimura; Masayoshi Kataoka; Toshiyuki Azuma; Yasuo Ito; Yoneo Tabata; Yasushi Aoki

    1988-01-01

    Dense helium, whose atomic separation is several Å near 4 K, shows new emission bands following excitation by fast nitrogen ions. These new emissions can be classified into three groups, which grow and disappear stepwise with increasing pressure, accompanied with lifetime shortening except for a group at the highest density. They are explained as clusters of helium excimers.

  3. Visible thermal emission from sub-band-gap laser excited cerium dioxide particles

    NASA Astrophysics Data System (ADS)

    Robinson, Richard D.; Spanier, Jonathan E.; Zhang, Feng; Chan, Siu-Wai; Herman, Irving P.

    2002-08-01

    Cerium dioxide particles excited in air with sub-band-gap radiation emit very broad radiation in the visible spectrum above a threshold intensity that decreases with increasing ambient temperature. Concomitant with this emission is the near disappearance of the Stokes and anti-Stokes Raman scattering peaks. Both phenomena are reversible in air up to just above threshold, and are seen for nanoparticles and several-micron-diameter particles with particle diameter comparable to or smaller than the laser focus. Temperature estimates using the Stokes/anti-Stokes scattering intensity ratio suggest there is laser heating due to small intragap absorption and possible nonlinear processes, given the very slow thermal conduction. The broad emission in this loose powder may well be due to thermal emission, on the basis of spectral fitting of the high-energy part of the spectrum to a blackbody radiator at approx1200-1400 degC, although luminescence from a new phase is a possibility. The sudden decrease in Raman scattering and increase in emission in air are consistent with a transition to a new, possibly luminescent, phase, as is the continued disappearance of the Raman peaks in forming gas when the laser power is reduced below the upstroke threshold. Oxygen point defects and their complexes may play an important role in many of these processes.

  4. Capturing electromagnetic emissions in the HF band possibly related to earthquake events

    NASA Astrophysics Data System (ADS)

    Koulouras, Gr; Kontakos, K.; Ninos, K.; Cavouras, D.; Nomicos, C.

    2009-04-01

    The purpose of this project was to capture electromagnetic emissions in the HF band. Possible correlations of these emissions prior to strong earthquakes were investigated. In order to record the variations of the electromagnetic field in a wide spectrum of frequencies up to the VHF band, a new device was designed and implemented by our research team. Ten prototype electromagnetic variation (EMV) field stations have already been installed in Greece, at the locations, Corfu, Ioannina, Ithomi (Kalamata), Kephalonia, Kozani, Mytilini, Rodos, Neapoli (Crete), and Bamos (Crete). This telemetric network was launched in 1999 and since it has been in constant operation. During the period 2005-2008, 14 strong earthquakes occurred in Greece with magnitude over Ms>=6. Of them, three events were recorded as precursor signals by only one station. Fractal analysis showed that these were precursors and not manmade signals. In eight EQs events, two or three stations recorded simultaneously precursor signals. In one EQ event, recordings in all stations were disturbed by strong magnetic storms twenty days before the event. In two EQs, events did not trigger any station in a time window of up to 10 days.

  5. A comparative study of stripe noise on MODIS and VIIRS thermal emissive bands

    NASA Astrophysics Data System (ADS)

    Bouali, Marouan; Ignatov, Alexander

    2012-09-01

    Following successful launch of NPP satellite in October 2011, the VIIRS instrument started delivering high quality radiances from which improved Sea Surface Temperature (SST) products are generated. The design of VIIRS instrument is similar to the MODIS sensor, which includes a double sided mirror re ecting the Earth's radiance to 10 individual detectors. Despite pre-launch characterization and the use of on-board calibration systems, persistent discrepancies between detectors radiometric responses often lead to striping in the level 1 imagery, which is then propagated into level 2 derived geophysical products. The determination of calibration- based uncertainties in level 1 radiances is necessary to further improve the quality of ocean products. This paper characterizes radiometric errors between the multiple detectors and mirror-sides in MODIS and VIIRS thermal emissive bands. A unidirectional variational model is applied on several scenes corresponding to clear-sky top-of- atmosphere ocean radiances to extract the scan line noise due to potential detector-to-detector, mirror-side and random stripes. Data from Terra and Aqua MODIS and NPP VIIRS sensors is used to evaluate and compare the degree of stripe noise in emissive bands used to generate SST products.

  6. Evaluation of Terra and Aqua MODIS thermal emissive band calibration consistency

    NASA Astrophysics Data System (ADS)

    Wenny, B. N.; Xiong, X.; Madhavan, S.

    2012-09-01

    Terra and Aqua MODIS have operated continuously for more than 12 and 10 years respectively and are key instruments for NASA's Earth Observing System missions. The 16 thermal emissive bands (TEB), covering wavelengths from 3.5 to 14.4 ?m with a nadir spatial resolution of 1 km are used to regularly generate a variety of atmosphere, ocean and land science products. As the sensors age well past their prime design life of 6 years, understanding the instrument on-orbit performance is necessary to maintain consistency between sensors in the long-term data records. Recurrent observations of Dome C, Antarctica by both Terra and Aqua MODIS over mission lifetime are used to track the calibration consistency and stability of the two sensors. A ground temperature sensor provides a proxy reference measurement useful for determining the relative bias between the two instruments. This technique is most useful for the land surface sensing bands, such as bands 29, 31 and 32, but can be applied to all other TEB to provide a metric to assess long-term trends. A change in the TEB calibration approach for the MODIS Collection 6 reprocessing mitigate a cold scene bias previously observed for retrievals of brightness temperatures well below the on-board blackbody calibrator temperature range (270-315 K). The impact of the Collection 6 calibration changes are illustrated using the Dome C observations.

  7. Lasing in ultra-narrow emission from GaAs quantum dots coupled with a two-dimensional layer.

    PubMed

    Jo, M; Mano, T; Sakoda, K

    2011-08-19

    We report electrically injected lasing in GaAs quantum dots (QDs) grown on GaAs(001) by droplet epitaxy. High-quality GaAs QDs with superior uniformity are formed using improved growth techniques involving the insertion of a two-dimensional layer, control of the As flux for GaAs crystallization, and thin AlGaAs layer capping with high-temperature annealing. The QDs show ultra-narrow luminescence with a linewidth of 20 meV. Ground-state lasing from a laser diode containing fivefold-stacked QD layers is observed at low temperature under pulsed operation. PMID:21775803

  8. 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

  9. 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.

  10. Controlled spontaneous emission of single molecules in a two-dimensional photonic band gap.

    PubMed

    Kaji, Takahiro; Yamada, Toshiki; Ito, Syoji; Miyasaka, Hiroshi; Ueda, Rieko; Inoue, Shin-ichiro; Otomo, Akira

    2013-01-01

    We have established a new platform to control the rate of spontaneous emission (SE) of organic molecules in the visible-light region using a combination of a two-dimensional (2D) photonic crystal (PC) slab made of TiO(2) and a single-molecule measurement method. The SE from single molecules of a perylenediimide derivative was effectively inhibited via a radiation field controlled by the 2D PC slab, which has a photonic band gap (PBG) for transverse-electric (TE)-polarized light. The fluorescence lifetimes of the single molecules were extended up to 5.5 times (28.6 ns) by the PBG effect. This result appears to be the first demonstration of drastic lifetime elongation for single molecules due to a PBG effect. PMID:23253079

  11. Quantum cascade lasers: ultrahigh-speed operation, optical wireless communication, narrow linewidth, and far-infrared emission

    Microsoft Academic Search

    F. Capasso; R. Paiella; R. Martini; R. Colombelli; C. Gmachl; T. L. Myers; M. S. Taubman; R. M. Williams; C. G. Bethea; K. Unterrainer; H. Y. Hwang; D. L. Sivco; A. Y. Cho; A. M. Sergent; H. C. Liu; E. A. Whittaker

    2002-01-01

    Abstract—Following an introduction to the history of the inven- tion of the quantum,cascade (QC) laser and of the band-structure engineering advances that have led to laser action over most of the mid-infrared (IR) and part of the far-IR spectrum, the paper provides a comprehensive review of recent developments that will likely enable important advances in areas such as optical commu-

  12. 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,

  13. Aromatic emission bands from the HII region ahead the Horsehead Nebula

    NASA Astrophysics Data System (ADS)

    Compiègne, M.; Abergel, A.; Verstraete, L.; Reach, W. T.; Habart, E.; Smith, J. D.; Boulanger, F.; Joblin, C.

    2009-01-01

    We present a study of Aromatic Infrared Band (AIBs) emission in the IC434 HII region ahead the Horsehead nebula as well as in the associated photodissociation region (PDR). AIBs are detected in the HII region and the correlation of the 11.3 ?m AIB with ionised gas lines shows that PAHs must be located in the ionised gas. The survival of AIBs emitters in the HII region could be due to the moderate intensity of the radiation field (G_0 ˜ 100) and the lack of photons with energy above ˜ 25 eV. The relatively high strength of the 11.3 ?m AIB regarding the other AIBs at 6.2, 7.7 and 8.6 ?m in the HII region spectrum is explained by the presence of neutral PAHs in the ionised gas while they are mostly ionised in the PDR. Our observations highlight a transition region between ionised and neutral PAHs observed with ideal conditions in our Galaxy. A scenario where PAHs can survive in HII regions and be preferantially neutral could explain the detection of a prominent 11.3 ?m band in other Spitzer observations.

  14. Very broad white-emission spectrum based organic light-emitting diodes by four exciplex emission bands.

    PubMed

    Zhu, Jianzhuo; Li, Wenlian; Han, Liangliang; Chu, Bei; Zhang, Guang; Yang, Dongfang; Chen, Yiren; Su, Zisheng; Wang, Junbo; Wu, Shuanghong; Tsuboi, Taiju

    2009-10-01

    White light is emitted by an organic light-emitting diode by inserting two blend layers of m-MTDATA:Al(DBM)(3) and TPD:Bphen between an m-MTDATA hole-transporting layer and a Bphen electron-transporting layer, where m-MTDATA, TPD, Al(DBM)(3), and Bphen are 4,4('),4('')-tris[methylpheny(phenyl)amino]-triphenylamine, N,N(')-bis(3-methylphenyl)-N,N(')-diphenylbenzidine, tris(dibenzoyl methane)-aluminum, and 4,7-diphenyl-1,10-phenanthroline molecules, respectively. The white-light spectrum consists of four broad bands that arise from blue-emitting TPD/Bphen, green-emitting m-MTDATA/Bphen, orange-emitting TPD/Al(DBM)(3), and red-emitting m-MTDATA/Al(DBM)(3) exciplexes, respectively, and strongly overlap at 400-760 nm. Any monomer emission is not generated. A high-color rendering index of 94.1, Commission Internationale de l'Eclairage-1931(x,y) coordinates of (0.33, 0.35), and correlated color temperature of 5477 K were obtained at 10 V. Discussion is given for the formation mechanism of the four exciplexes. PMID:19794777

  15. Spontaneous emission inhibition of telecom-band quantum disks inside single nanowire on different substrates

    E-print Network

    Birowosuto, M D; Yokoo, A; Takiguchi, M; Notomi, M

    2014-01-01

    We investigate the inhibited spontaneous emission of telecom-band InAs quantum disks (Qdisks) in InP nanowires (NWs). We have evaluated how the inhibition is affected by different disk diameter and thickness. We also compared the inhibition in standing InP NWs and those NWs laying on silica (SiO2), and silicon (Si) substrates. We found that the inhibition is altered when we put the NW on the high-refractive index materials of Si. Experimentally, the inhibition factor $\\zeta$ of the Qdisk emission at 1,500 nm decreases from 4.6 to 2.5 for NW on SiO2 and Si substrates, respectively. Those inhibitions are even much smaller than that of 6.4 of the standing NW. The inhibition factors well agree with those calculated from the coupling of the Qdisk to the fundamental guided mode and the continuum of radiative modes. Our observation can be useful for the integration of the NW as light sources in the photonic nanodevices.

  16. Measurement of spontaneous-emission enhancement near the one-dimensional photonic band edge of semiconductor heterostructures

    Microsoft Academic Search

    Michael D. Tocci; Michael Scalora; Mark J. Bloemer; Jonathan P. Dowling; Charles M. Bowden

    1996-01-01

    We present results of an experimental investigation into alteration of the spontaneous emission spectrum of GaAs from within one-dimensional photonic band gap (PBG) structures. The PBG samples are multilayer AlAs\\/Al0.2Ga0.8As\\/GaAs p-i-n light-emitting diodes, with layers arranged as a distributed Bragg reflector. The emission spectra normal to the layers are measured, and we use a simple method to model the power

  17. Prepulse-enhanced narrow bandwidth soft x-ray emission from a low debris, subnanosecond, laser plasma source

    NASA Astrophysics Data System (ADS)

    Dunne, P.; O'Sullivan, G.; O'Reilly, D.

    2000-01-01

    Soft x-ray emission from 170 ps laser-produced plasmas formed on cerium-doped borosilicate glasses has been recorded in the 7-17 nm region using a 2 m grazing incidence vacuum spectrograph. Broadband spectra have been recorded on photographic plates, while intensity comparisons have been made using an absolutely calibrated, extreme ultraviolet sensitive photodiode. The use of a laser prepulse to prime the target has been seen to enhance the emission with the maximum flux produced at an interpulse delay of 5.1 ns. The peak conversion efficiency is found to be 4.8%±1.5% into 3% bandwidth, centered at 8.8 nm. In addition, the level of debris emitted by the target is greatly reduced by comparison with solid metallic targets.

  18. The virtual-photon effects in spontaneous emission from an atom embedded in a photonic band gap structure

    Microsoft Academic Search

    Zhengdong Liu; Y. Lin; Shiyao Zhu; K. Shang; Liang Zeng

    1999-01-01

    In a three-level atom embedded in a photonic band gap structure, the spontaneous emission is studied both with and without rotating-wave approximation. The virtual-photon-localized field is found, which causes a greater population of the atom trapped in its upper states.

  19. 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.

  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. [Max Planck Institute for Extraterrestrial Physics, Postfach 1312, 85741 Garching (Germany)

    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. Optical study of narrow band gap InAsxSb1 -x (x =0 , 0.25, 0.5, 0.75, 1) alloys

    NASA Astrophysics Data System (ADS)

    Namjoo, Shirin; Rozatian, Amir S. H.; Jabbari, Iraj; Puschnig, Peter

    2015-05-01

    The structural, electronic, and optical properties of InAs, InSb, and their ternary alloys InAsxSb1 -x (x =0.25 , 0.5, 0.75) are investigated within density functional theory utilizing the wien2k package. We find that the lattice constants and bulk moduli as a function of x are in best agreement with Vegard's linear rule. When computing the electronic band structures with the modified Becke-Johnson exchange-correlation functional (mBJLDA), our results for the band gaps of InAs, InSb, and their ternary alloys are in good agreement with the available experimental results while the conventional Wu-Cohen generalized gradient approximation (GGA) functional leads to zero or close to zero band gaps. In particular, our mBJLDA results confirm experimental evidence that the minimum band gap occurs for As concentrations around x ?0.3 . Furthermore, we investigate the dielectric function of these compounds within the random phase approximation using both the Wu-Cohen GGA and the mBJLDA functionals. While the mBJLDA results of our fully first-principles calculations show good agreement of the peak positions in ?2(? ) with experiments, the peaks in the optical spectra based on the Wu-Cohen GGA band structure appear redshifted compared to experiment. We further identify the interband transitions responsible for the structures in the spectra. Looking at the optical matrix element, we note that the major peaks are dominated by transition from the Sb 5 p (As 4 p ) states to In s states for InSb and InAs0.25Sb0.75 (InAs, InAs0.75Sb0.25 , and InAs0.5Sb0.5 ).

  2. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 40, NO. 10, OCTOBER 2002 2117 Sea Surface Emissivity Observations at L-Band

    E-print Network

    Reising, Steven C.

    Emissivity Observations at L-Band: First Results of the Wind and Salinity Experiment WISE 2000 A. Camps-Neira, Member, IEEE Abstract--Sea surface salinity can be measured by passive mi- crowave remote sensing at L-band in the radiometric measurements at L-band, their comparison with nu- merical models, and the implications

  3. Out-of-band emission suppression techniques based on a generalized OFDM framework

    NASA Astrophysics Data System (ADS)

    You, Zihao; Fang, Juan; Lu, I.-Tai

    2014-12-01

    Orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) systems suffer from the large out-of-band emission (OOBE) that may interfere with other users. Since most existing OFDM OOBE suppression schemes are derived on the base of an original OFDM system without any other scheme, we first propose a generalized OFDM framework that is capable of describing these schemes no matter whether any one or more of the schemes is applied. Then, according to the place where these schemes are implemented in our framework, they are classified into three groups, namely symbol mapping techniques, precoding techniques, and time-domain techniques. Finally, based on the proposed framework, we propose three new schemes by combining a precoding scheme named singular value decomposition (SVD) precoding with three other schemes from the three groups, namely spectral precoding, N-continuous symbol mapping, and filtering. Numerical results show the power spectral density (PSD), peak-to-average power ratio (PAPR), and bit error rate (BER) performances of the three proposed schemes. Since the individual schemes have complementary characteristics, the three proposed combined schemes are constructed to maintain the merits and avoid the drawbacks of the individual schemes involved. Thus, it is demonstrated that the proposed framework can be employed to develop other new combined OOBE suppression schemes tailoring to some specific practical needs.

  4. Indirect Band Gap Emission by Hot Electron Injection in Metal/MoS2 and Metal/WSe2 Heterojunctions.

    PubMed

    Li, Zhen; Ezhilarasu, Goutham; Chatzakis, Ioannis; Dhall, Rohan; Chen, Chun-Chung; Cronin, Stephen B

    2015-06-10

    Transition metal dichalcogenides (TMDCs), such as MoS2 and WSe2, are free of dangling bonds and therefore make more "ideal" Schottky junctions than bulk semiconductors, which produce Fermi energy pinning and recombination centers at the interface with bulk metals, inhibiting charge transfer. Here, we observe a more than 10× enhancement in the indirect band gap photoluminescence of transition metal dichalcogenides (TMDCs) deposited on various metals (e.g., Cu, Au, Ag), while the direct band gap emission remains unchanged. We believe the main mechanism of light emission arises from photoexcited hot electrons in the metal that are injected into the conduction band of MoS2 and WSe2 and subsequently recombine radiatively with minority holes in the TMDC. Since the conduction band at the K-point is 0.5 eV higher than at the ?-point, a lower Schottky barrier exists for the ?-point band, making electron injection more favorable. Also, the ? band consists of the sulfur pz orbital, which overlaps more significantly with the electron wave functions in the metal. This enhancement in the indirect emission only occurs for thick flakes of MoS2 and WSe2 (?100 nm) and is completely absent in monolayer and few-layer (?10 nm) flakes. Here, the flake thickness must exceed the depletion width of the Schottky junction, in order for efficient radiative recombination to occur in the TMDC. The intensity of this indirect peak decreases at low temperatures, which is consistent with the hot electron injection model. PMID:25993397

  5. New probes of GRB prompt emission properties using wide-band spectroscopy by Suzaku Wide-band All-sky Monitor

    SciTech Connect

    Ohno, M.; Kokubun, M.; Suzuki, M.; Takahashi, T. [ISAS/JAXA, 3-1-1 Yoshinodai, Sagamihara, 229-8510 (Japan); Ioka, K. [Theory Division, KEK (High Energy Accelerator Research Organization) 1-1 Oho, Tsukuba 305-0801 (Japan); Uehara, T.; Takahashi, T.; Fukazawa, Y.; Kira, C.; Hanabata, Y. [Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8526 (Japan); Yamaoka, K.; Sugita, S. [Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, 229-8558 (Japan); Terada, Y; Urata, Y.; Onda, K.; Kodaka, N.; Endo, A.; Morigami, K.; Sugasahara, T.; Iwakiri, W. [Saitama University, 255 Shimo-Okubo, Sakura, Saitama, 338-8570 (Japan)] (and others)

    2009-05-25

    Although the afterglow observations in HETE-2 and Swift era have revealed a lot of afterglow properties of gamma-ray bursts (GRBs), we still have poor understanding of the prompt gamma-ray emission, such as the emission mechanism of the prompt emission and differences between short and long duration GRBs. We have observed many prompt emission of GRBs by Suzaku Wide-band All-sky Monitor in wide energy range of 50-5000 keV, with very large effective area of 400 cm{sup 2} even at 1 MeV. Furthermore, a combination of the Suzaku/WAM and Swift data provides us not only wider energy range of 15-5000 keV but also redshift information even for some short GRBs. Thanks to these information, we can firstly investigate an intrinsic correlation for short GRBs like E{sub peak}-L{sub iso} relation, and we can derive the same type of relation for time-resolved spectra of long GRBs in finer time-scale with higher statistics than ever before. These results could be used to discuss the differences between short and long GRBs, and our time-resolved E{sub peak}-L{sub iso} relation also could be used as both more appropriate redshift indicator and new probe of the fireball dynamics.

  6. Fig. 2, we compare our observed narrow-band image to calculated Lya surface brightness maps with an opening angle w 1108 and

    E-print Network

    Davis, James C.

    II lines typical in extended emission around radio-loud quasars14 . We did not detect any side B). The gas density scale, nHI, 1, determines the normalization of the surface brightness profile density profile. An exponential gas density profile provides an equally good fit to the data. The extended

  7. Emission band and continuum photometry of Comet West \\/1975n\\/. I - Heliocentric dependence of the flux in the emission bands and the continuum

    Microsoft Academic Search

    K. R. Sivaraman; G. S. D. Babu; M. K. V. Bappu; M. Parthasarathy

    1979-01-01

    Spectrum scans of the coma of Comet West (1975n) covering the range lambdalambda3700--5700 Å were made on eight nights when the heliocentric distance of the comet varied from 0.588 to 0.853 AU. These have been used to derive the absolute flux in the CN(0,0), C3(4050), C2(1, 0) and C2(0, 0) bands as well as in the continuum. Enhancements in the

  8. Radio wave emissions in the v.l.f-band observed near the auroral zone--II the physical properties of the emissions

    Microsoft Academic Search

    Leiv Harang; Knut N. Hauge

    1965-01-01

    The direction of arrival of the v.l.f.-emission in the 8 kc\\/s bands has been studied using two crossed loops with their planes lying in EW and NS directions, and by switching the loops alternately to the same amplifier channel. The v.l.f.-noise level was higher in the EW than in the NS direction, and this higher EW noise level was maintained

  9. Photoluminescent Evolution Induced by Structural Transformation Through Thermal Treating in the Red Narrow-Band Phosphor K2GeF6:Mn(4.).

    PubMed

    Wei, Ling-Ling; Lin, Chun Che; Wang, Yi-Ying; Fang, Mu-Huai; Jiao, Huan; Liu, Ru-Shi

    2015-05-27

    This study explored optimal preparation conditions for K2GeF6:Mn(4+) red phosphors by using chemical coprecipitation method. The prepared hexagonal P3?m1 K2GeF6:Mn(4+) exhibited efficient red emission, high color purity, good Mn(4+) concentration stability, and low thermal quenching. Structural evolution from hexagonal P3?m1 to P63mc and then P63mc to cubic Fm3m occurred after thermal treatment at approximately 400 and 500 °C, respectively. Hexagonal P63mc phase showed an obvious zero phonon line peak at 621 nm, whereas cubic Fm3m phase showed no red emission. Yellowish K2GeF6:Mn(4+) with both hexagonal P3?m1 and P63mc symmetries are promising commercial red phosphors for white light-emitting diodes. PMID:25961499

  10. Effect of N2 and H2 plasma treatments on band edge emission of ZnO microrods.

    PubMed

    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

  11. 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

  12. Evaluation of Terra and Aqua MODIS thermal emissive band response versus scan angle

    NASA Astrophysics Data System (ADS)

    Wenny, B. N.; Wu, A.; Madhavan, S.; Xiong, X.

    2014-10-01

    Terra and Aqua MODIS have operated near-continuously for over 14 and 12 years, respectively, and are key instruments for NASA's Earth Observing System. Observations from the 16 thermal emissive bands (TEB), covering wavelengths from 3.5 to 14.4 ?m with a nadir spatial resolution of 1 km are used to regularly generate a variety of atmosphere, ocean and land science products. The TEB detectors are calibrated using scan-by-scan observations of an on-board blackbody (BB). The current response versus scan angle (RVS) of the scan mirror was derived using a spacecraft deep-space pitch maneuver for Terra MODIS and characterized during prelaunch for Aqua MODIS. Earth view (EV) data over the complete range of angles of incidence (AOI) can be used to evaluate the on-orbit performance of the TEB RVS over the mission lifetime. Three approaches for tracking the TEB RVS on-orbit using EV observations are formulated. The first approach uses the multiple daily observations of Dome C BT at different AOI and their trend relative to coincident measurements from a ground temperature sensor. The second approach uses brightness temperatures (BT) retrieved over the cloud-free ocean to derive the trends at 13 AOI over the mission lifetime. The third approach tracks the dn response (normalized to the BB AOI) across the full swath width for Antarctic granules with the Dome C site at nadir. The viability of the three approaches is assessed and the long-term stability of the TEB RVS for both MODIS instruments is determined.

  13. Methane oxidation behind reflected shock waves: Ignition delay times measured by pressure and flame band emission

    NASA Technical Reports Server (NTRS)

    Brabbs, T. A.; Robertson, T. F.

    1986-01-01

    Ignition delay data were recorded for three methane-oxygen-argon mixtures (phi = 0.5, 1.0, 2.0) for the temperature range 1500 to 1920 K. Quiet pressure trances enabled us to obtain delay times for the start of the experimental pressure rise. These times were in good agreement with those obtained from the flame band emission at 3700 A. The data correlated well with the oxygen and methane dependence of Lifshitz, but showed a much stronger temperature dependence (phi = 0.5 delta E = 51.9, phi = 1.0 delta = 58.8, phi = 2.0 delta E = 58.7 Kcal). The effect of probe location on the delay time measurement was studied. It appears that the probe located 83 mm from the reflecting surface measured delay times which may not be related to the initial temperature and pressure. It was estimated that for a probe located 7 mm from the reflecting surface, the measured delay time would be about 10 microseconds too short, and it was suggested that delay times less than 100 microsecond should not be used. The ignition period was defined as the time interval between start of the experimental pressure rise and 50 percent of the ignition pressure. This time interval was measured for three gas mixtures and found to be similar (40 to 60 micro sec) for phi = 1.0 and 0.5 but much longer (100 to 120) microsecond for phi = 2.0. It was suggested that the ignition period would be very useful to the kinetic modeler in judging the agreement between experimental and calculated delay times.

  14. DETECTION OF K{sub S} -BAND THERMAL EMISSION FROM WASP-3b

    SciTech Connect

    Zhao Ming; Wright, Jason [Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802 (United States); Milburn, Jennifer; Hinkley, Sasha [Department of Astronomy, California Institute of Technology, Pasadena, CA 91009 (United States); Barman, Travis [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Swain, Mark R. [Jet Propulsion Lab, California Institute of Technology, Pasadena, CA 91009 (United States); Monnier, John D., E-mail: mingzhao@psu.edu [Department of Astronomy, University of Michigan, Ann Arbor, MI 48104 (United States)

    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.

  15. 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.

  16. The effect of the ionosphere on remote sensing of sea surface salinity from space: absorption and emission at L band

    Microsoft Academic Search

    David M. Le Vine; Saji Abraham

    2002-01-01

    The purpose of this work is to examine the effects of Faraday rotation and attenuation\\/emission in the ionosphere in the context of a future remote sensing system in space to measure salinity. Sea surface salinity is important for understanding ocean circulation and for modeling energy exchange with the atmosphere. A passive microwave sensor in space operating near 1.4 GHz (L-band)

  17. Band-tunable color cone lasing emission based on a dye-doped cholesteric liquid crystal film

    Microsoft Academic Search

    Chia-Rong Lee; S.-H. Lin; H.-C. Yeh; T.-D. Ji; J.-H. Liu; P.-C. Yang; T.-S. Mo; S.-Y. Huang; C.-T. Kuo; K.-Y. Lo; Andy Y. Fuh

    2010-01-01

    This investigation reports for the first time a novel phenomenon, called band-tunable color cone lasing emission (CCLE), based on a single-pitched one-dimensional photonic crystal-like dye-doped cholesteric liquid crystal (DDCLC) cell. The lasing wavelength in the CCLE pattern is distributed continuously at 676.7-595.6 nm as the oblique angle increases continuously from 0° to 50° relative to the helical axis. The variation

  18. Microscopic origin of light emission in Al_yGa_{1-y}N/GaN superlattice: Band profile and active site

    E-print Network

    Cai, Duanjun; Guo, Guang-Yu; 10.1103/PhysRevB.80.045311

    2009-01-01

    We present first-principles calculations of AlGaN/GaN superlattice, clarifying the microscopic origin of the light emission and revealing the effect of local polarization within the quantum well. Profile of energy band and distributions of electrons and holes demonstrate the existence of a main active site in the well responsible for the main band-edge light emission. This site appears at the position where the local polarization becomes zero. With charge injection, the calculated optical spectra show that the broadening of the band gap at the active site leads to the blueshift of emission wavelength.

  19. 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.

  20. PAH Emission in the Orion Bar

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse; Sloan, G. C.

    1996-01-01

    The emission from polycyclic aromatic hydrocarbons (PAH's) in the Orion Bar region is investigated using a combination of narrow-band imaging and long-slit spectroscopy. The goal was to study how the strength of the PAH bands vary with spatial position in this edge-on photo-dissociation region. The specific focus here is how these variations constrain the carrier of the 3.4 micron band.

  1. Application of band-target entropy minimization to infrared emission spectroscopy and the reconstruction of pure component emissivities from thin films and liquid samples.

    PubMed

    Cheng, Shuying; Rajarathnam, D; Meiling, Tan; Garland, Marc

    2006-05-01

    Thermal emission spectral data sets were collected for a thin solid film (parafilm) and a thin liquid film (isopropanol) on the interval of 298-348 K. The measurements were performed using a conventional Fourier transform infrared (FT-IR) spectrometer with external optical bench and in-house-designed emission cell. Both DTGS and MCT detectors were used. The data sets were analyzed with band-target entropy minimization (BTEM), which is a pure component spectral reconstruction program. Pure component emissivities of the parafilm, isopropanol, and thermal background were all recovered without any a priori information. Furthermore, the emissivities were obtained with increased signal-to-noise ratios, and the signals due to absorbance of thermal radiation by gas-phase moisture and CO2 were significantly reduced. As expected, the MCT results displayed better signal-to-noise ratios than the DTGS results, but the latter results were still rather impressive given the low temperatures used in this study. Comparison is made with spectral reconstruction using the orthogonal projection approach-alternating least squares (OPA-ALS) technique. This contribution introduces the primary equation for emission spectral reconstruction using BTEM and discusses some of the unusual characteristics of thermal emission and their impact on the analysis. PMID:16756703

  2. Enhanced photonic band edge laser emission in a cholesteric liquid crystal resonator

    Microsoft Academic Search

    Ying Zhou; Yuhua Huang; Zhibing Ge; Liang-Pin Chen; Qi Hong; Thomas X. Wu; Shin-Tson Wu

    2006-01-01

    A highly efficient photonic band edge dye-doped cholesteric liquid crystal (CLC) laser is demonstrated. By sandwiching an active CLC cell within a resonator consisting of two passive CLC reflectors, the lasing efficiency is dramatically enhanced. Theoretical analysis using the improved 4×4 transfer matrix and scattering matrix shows that the band edge laser mode can be supported by the external CLC

  3. 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.

  4. 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.

  5. Effect of multiple conduction bands on high-harmonic emission from dielectrics

    NASA Astrophysics Data System (ADS)

    Hawkins, Peter G.; Ivanov, Misha Yu.; Yakovlev, Vladislav S.

    2015-01-01

    We find that, for sufficiently strong mid-IR fields, transitions between different conduction bands play an important role in the generation of high-order harmonics in a dielectric. The transitions make a significant contribution to the harmonic signal, and they can create a single effective band for the motion of an electron wave packet. We show how high harmonic spectra produced during the interaction of ultrashort laser pulses with periodic solids provide a spectroscopic tool for understanding the effective band structure that controls electron dynamics in these media.

  6. 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.

  7. Optical Spectrograph and InfraRed Imaging System (OSIRIS) observations of mesospheric OH A2?+-X2? 0-0 and 1-1 band resonance emissions

    Microsoft Academic Search

    R. L. Gattinger; D. A. Degenstein; E. J. Llewellyn

    2006-01-01

    Although only a minor species, the OH molecule plays an important role in the photochemical control of mesospheric ozone density and has been the target of a number of observational programs, principally through the OH A2?+-X2? 0-0 band emission at 308 nm. This emission band arises from solar resonance fluorescence excitation of OH X2? ground state molecules, and its observation

  8. 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.

  9. Electronic Structure in Valence Band of Nd-Substituted Bi4Ti3O12 Single Crystal Probed by Soft-X-Ray Emission Spectroscopy

    Microsoft Academic Search

    Tohru Higuchi; Yuji Noguchi; Takashi Goto; Masaru Miyayama; Shik Shin; Kazuhiro Kaneda; Takeshi Hattori; Takeyo Tsukamoto

    2005-01-01

    The electronic structure of Nd3+-substituted Bi4Ti3O12 single crystals was studied by soft-X-ray emission spectroscopy. The valence band is in good accordance with the band calculation. The valence band is mainly composed of the O 2p state hybridized with Ti 3d and Bi 6s states. The hybridization effect between the Ti 3d and O 2p states increases with Nd3+ substitution, indicating

  10. THE 217.5 nm BAND, INFRARED ABSORPTION, AND INFRARED EMISSION FEATURES IN HYDROGENATED AMORPHOUS CARBON NANOPARTICLES

    SciTech Connect

    Duley, W. W. [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)] [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada); Hu, Anming, E-mail: wwduley@uwaterloo.ca, E-mail: a2hu@uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, Centre for Advanced Material Joining, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)] [Department of Mechanical and Mechatronics Engineering, Centre for Advanced Material Joining, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)

    2012-12-20

    We report on the preparation of hydrogenated amorphous carbon nanoparticles whose spectral characteristics include an absorption band at 217.5 nm with the profile and characteristics of the interstellar 217.5 nm feature. Vibrational spectra of these particles also contain the features commonly observed in absorption and emission from dust in the diffuse interstellar medium. These materials are produced under ''slow'' deposition conditions by minimizing the flux of incident carbon atoms and by reducing surface mobility. The initial chemistry leads to the formation of carbon chains, together with a limited range of small aromatic ring molecules, and eventually results in carbon nanoparticles having an sp {sup 2}/sp {sup 3} ratio Almost-Equal-To 0.4. Spectroscopic analysis of particle composition indicates that naphthalene and naphthalene derivatives are important constituents of this material. We suggest that carbon nanoparticles with similar composition are responsible for the appearance of the interstellar 217.5 nm band and outline how these particles can form in situ under diffuse cloud conditions by deposition of carbon on the surface of silicate grains. Spectral data from carbon nanoparticles formed under these conditions accurately reproduce IR emission spectra from a number of Galactic sources. We provide the first detailed fits to observational spectra of Type A and B emission sources based entirely on measured spectra of a carbonaceous material that can be produced in the laboratory.

  11. Production of N2 Vegard-Kaplan and other triplet band emissions in the dayglow of Titan

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Anil; Jain, Sonal Kumar

    2012-04-01

    Recently the Cassini Ultraviolet Imaging Spectrograph (UVIS) has revealed the presence of N2 Vegard-Kaplan (VK) band A3?u+-X1?g+ emissions in Titan's dayglow limb observation. We present model calculations for the production of various N2 triplet states (viz., A3?u+,B3?g,C3?u,E3?u,W3?u, and B3?u ) in the upper atmosphere of Titan. The Analytical Yield Spectra technique is used to calculate steady state photoelectron fluxes in Titan's atmosphere, which are in agreement with those observed by the Cassini's CAPS instrument. Considering direct electron impact excitation, inter-state cascading, and quenching effects, the population of different levels of N2 triplet states are calculated under statistical equilibrium. Densities of all vibrational levels of each triplet state and volume production rates for various triplet states are calculated in the model. Vertically integrated overhead intensities for the same date and lighting conditions as reported by the UVIS observations for N2 Vegard-Kaplan A3?u+-X1?g+, First Positive B3?g-A3?u+, Second Positive (C3?u - B3?g), Wu-Benesch (W3?u - B3?g), and Reverse First Positive bands of N2 are found to be 132, 114, 19, 22, and 22 R, respectively. Overhead intensities are calculated for each vibrational transition of all the triplet band emissions of N2, which span a wider spectrum of wavelengths from ultraviolet to infrared. The calculated limb intensities of total and prominent transitions of VK band are presented. The model limb intensity of VK emission within the 150-190 nm wavelength region is in good agreement with the Cassini UVIS observed limb profile. An assessment of the impact of solar EUV flux on the N2 triplet band emission intensity has been made by using three different solar flux models, viz., Solar EUV Experiment (SEE), SOLAR2000 (S2K) model of Tobiska (Tobiska, W.K. [2004]. Adv. Space Res. 34, 1736-1746), and HEUVAC model of Richards et al. (Richards, P.G., Woods, T.N., Peterson, W.K. [2006]. Adv. Space Res. 37 (2), 315-322). The calculated N2 VK band intensity at the peak of limb intensity due to S2K and HEUVAC solar flux models is a factor of 1.2 and 0.9, respectively, of that obtained using SEE solar EUV flux. The effects of higher N2 density and solar zenith angle on the emission intensity are also studied. The model predicted N2 triplet band intensities during moderate (F10.7 = 150) and high (F10.7 = 240) solar activity conditions, using SEE solar EUV flux, are a factor of 2 and 2.8, respectively, higher than those during solar minimum (F10.7 = 68) condition.

  12. Characterization of Al and Mg alloys from their x-ray emission bands

    E-print Network

    their electronic structure Keywords : alloys, intermetallics, electronic structure, valence states, x-ray emission, and intermetallics). Two methods based on x-ray emission spectroscopy are proposed to determine the phases and make the use of automobiles more economical. However, magnesium has a hexagonal closed-packed structure

  13. Spontaneous and Stimulated-Emission Spectra of CdSnP2

    Microsoft Academic Search

    J. L. Shay; L. M. Schiavone; E. Buehler; J. H. Wernick

    1972-01-01

    We report the band-edge photoluminescence spectra of CdSnP2 crystals lightly doped with Cu or Ag. The emission from CdSnP2:Cu is dominated by a broad band 0.13 eV below the band gap at 1.240 eV (2°K). The emission from CdSnP2:Ag is much stronger and is dominated by a narrow band-to-band emission with three impurity peaks at slightly longer wavelengths. At the

  14. 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.

  15. Excitation-emission-matrix fluorescence spectroscopy applied to humic acid bands in coral reefs

    Microsoft Academic Search

    B. J. H. Matthews; A. C. Jones; N. K. Theodorou; A. W. Tudhope

    1996-01-01

    An investigation of the three-dimensional excitation-emission-matrix (EEM) fluorescence spectra of humic acids and other organic matter from corals and other sources is reported, the results of which have implications for the use of corals as paleoenvironmental indicators. Four characteristic excitation\\/emission peaks were identified in the samples studied, at 310430, 340450, 390490 and 280(320–350) nm, the last of these attributed to

  16. Photonic band-gap effects upon the light emission from a dye-polymer-opal composite

    Microsoft Academic Search

    S. G. Romanov; T. Maka; C. M. Sotomayor Torres; M. Müller; R. Zentel

    1999-01-01

    A polymeric photonic crystal formed by impregnating an opal with a Coumarin 6 dye containing polymer has been prepared and its emission properties studied by angular-resolved photoluminescence. A strong spectral redistribution of the luminescence intensity was observed in the dye-polymer-opal compared to that of the dye-polymer reference sample. The emission spectrum shows a marked distortion compared with the reference sample,

  17. Photonic band-gap effects upon the light emission from a dye–polymer–opal composite

    Microsoft Academic Search

    S. G. Romanov; T. Maka; C. M. Sotomayor Torres; R. Zentel

    1999-01-01

    A polymeric photonic crystal formed by impregnating an opal with a Coumarin 6 dye containing polymer has been prepared and its emission properties studied by angular-resolved photoluminescence. A strong spectral redistribution of the luminescence intensity was observed in the dye-polymer-opal compared to that of the dye-polymer reference sample. The emission spectrum shows a marked distortion compared with the reference sample,

  18. 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 ...

  19. A Simple Model of the Bare Soil Microwave Emission at L-Band

    Microsoft Academic Search

    Maria Jose Escorihuela; Yann H. Kerr; Patricia de Rosnay; Jean-Pierre Wigneron; Jean-Christophe Calvet; François Lemaître

    2007-01-01

    A simple reflectivity model of a bare soil at L-band is developed to account for the effects of soil roughness at different angles and polarizations. This model was developed using a long-term dataset acquired over the bare soil in the framework of the Surface Monitoring Of the Soil Reservoir EXperiment (SMOSREX). It is shown that the roughness effects are different

  20. Fullerenes as carriers of extinction, diffuse interstellar bands and anomalous microwave emission

    Microsoft Academic Search

    Susana Iglesias-Groth

    2008-01-01

    According to semiempirical models, photoabsorption by fullerenes (single and multishell) could explain the shape, width and peak energy of the most prominent feature of the interstellar absorption, the UV bump at 2175 Å. Other weaker transitions are predicted in the optical and near-infrared providing a potential explanation for diffuse interstellar bands. In particular, we find that several fullerenes could contribute

  1. Analysis of GeV-band gamma-ray emission from SNR RX J1713.7-3946

    E-print Network

    Federici, S; Telezhinsky, I; Wilhelm, A; Dwarkadas, V V

    2015-01-01

    RX J1713.7-3946 is the brightest shell-type Supernova remnant (SNR) of the TeV gamma-ray sky. Earlier Fermi-LAT results on low-energy gamma-ray emission suggested that, despite large uncertainties in the background determination, the spectrum is inconsistent with a hadronic origin. We update the GeV-band spectra using improved estimates for the diffuse galactic gamma-ray emission and more than doubled data volume. We further investigate the viability of hadronic emission models for RX J1713.7-3946. We produced a high-resolution map of the diffuse Galactic gamma-ray background corrected for HI self-absorption and used it in the analysis of more than 5~years worth of Fermi-LAT data. We used hydrodynamic scaling relations and a kinetic transport equation to calculate the acceleration and propagation of cosmic-rays in SNR. We then determined spectra of hadronic gamma-ray emission from RX J1713.7-3946, separately for the SNR interior and the cosmic-ray precursor region of the forward shock, and computed flux varia...

  2. Non-LTE modeling of narrow emission components of He and Ca lines in optical spectra of classical T Tauri stars

    NASA Astrophysics Data System (ADS)

    Dodin, A. V.; Lamzin, S. A.; Sitnova, T. M.

    2013-05-01

    Using LTE calculations of the structure of T Tauri stellar atmospheres heated by radiation from an accretion shock (Dodin and Lamzin 2012), we have calculated the spectrum of the hot spot emerging on the stellar surface by taking into account non-LTE effects for He I, He II, Ca I, and Ca II. Assuming the pre-shock gas density N 0 and velocity V 0 to be the same at all points of the accretion stream cross section, we have calculated the spectrum of the star+circular spot system at various N 0, V 0, and parameters characterizing the star and the spot. Using nine stars as an example, we show that the theoretical optical spectra reproduce well the observed veiling of photospheric absorption lines as well as the profiles and intensities of the so-called narrow components of He II and Ca I emission lines with an appropriate choice of parameters. The accreted gas density in all of the investigated stars except DK Tau has been found to be N 0 > 1012 cm-3. We have managed to choose the parameters for eight stars at a calcium abundance in the accreted gas ? Ca equal to the solar one, but we have been able to achieve agreement between the calculations and observations for TW Hya only by assuming ? Ca to be approximately a factor of 3 lower than the solar one. The estimated parameters do not depend on interstellar extinction, because they have been determined from the spectra normalized to the continuum level. The calculated intensity of Ca II lines has turned out to be lower than the observed one, but this contradiction can be eliminated by assuming that, in addition to the accreted gas with a high density N 0, a more rarefied gas also falls onto the star. The theoretical equivalent widths and relative intensities of the subordinate He I lines disagree significantly with the observations. This is apparently because non-LTE effects should be taken into account when calculating the structure of the upper layers of the hot spot, the accuracy of the cross sections for collisional processes from upper levels is insufficient, and the spot inhomogeneity should probably be taken into account.

  3. 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±119pg/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

  4. 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.

  5. Fermi gamma-ray and multi-wave band emission from TeV active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Xiong, Dingrong; Zhang, Haojing; Zhang, Xiong; Zheng, Yonggang; Liu, Wenguang; Mao, Lisheng; Huang, Bangrong; Kang, Ting; Cha, Yongjuan; Guo, Fei

    2013-01-01

    Using ?-ray data detected by Fermi Large Area Telescope (LAT) and multi-wave band data for 40 TeV active galactic nuclei (AGNs), we have studied the correlations between flux densities ( F R, F IR, F O, F X and F ? ) in the radio, infrared, optical, X-ray and ?-ray wave bands. Our results are the following: (1) For TeV HSP BL Lacertae objects (THBLs), there are strong correlations between F ? and F R and between F ? and F IR in all states (average/high/low); (2) The TeV radio galaxies (TRGs) deviate from the area occupied by THBLs; (3) The TeV flat-spectrum radio quasars (TFSRQs) have much stronger ?-ray emission than THBLs; (4) For THBLs, there are weak correlations between F ? and F X in all states as well as between F ? and F O in both average and high states, and a strong correlation between F ? and F O in the low state; (5) For THBLs, there are strong correlations between F O and F R in both low and average states as well as between F O and F IR in all states and between F IR and F R in all states, but no strong correlations among other bands are found. From these results, we suggest that for THBLs, the synchrotron self-Compton radiation (SSC) is the main mechanism of high energy ?-ray emission and the inverse Compton scattering of circum-nuclear dust is likely to be a important complementary mechanism. Compared with THBLs, TRGs and TFSRQs may have a different origin of high energy ?-ray.

  6. No detection of L-band radio emission from SN 2007gr by GMRT

    Microsoft Academic Search

    Alak K. Ray

    2007-01-01

    Sayan Chakraborti (Tata Institute of Fundamental Research, Mumbai, (TIFR)), Poonam Chandra (Univ Virginia and National Radio Astronomical Observatory, Charlottesville), Nirupam Roy (National Centre for Radio Astrophysics (NCRA-TIFR), Pune, and Alak Ray (TIFR) report on the Target of Opportunity observation of SN 2007gr on 2007 Aug 24 by the Giant Metrewave Radio Telescope (GMRT) in the L-band between UT 0200 to

  7. No detection of L-band radio emission from SN 2007gr by GMRT

    NASA Astrophysics Data System (ADS)

    Ray, Alak K.

    2007-08-01

    Sayan Chakraborti (Tata Institute of Fundamental Research, Mumbai, (TIFR)), Poonam Chandra (Univ Virginia and National Radio Astronomical Observatory, Charlottesville), Nirupam Roy (National Centre for Radio Astrophysics (NCRA-TIFR), Pune, and Alak Ray (TIFR) report on the Target of Opportunity observation of SN 2007gr on 2007 Aug 24 by the Giant Metrewave Radio Telescope (GMRT) in the L-band between UT 0200 to 0400.

  8. MODIS thermal emissive bands calibration algorithm and on-orbit performance

    Microsoft Academic Search

    Xiaoxiong Xiong; K. Chiang; Bruce Guenther; William L. Barnes

    2003-01-01

    The MODerate Resolution Imaging Spectroradiometer (MODIS)is one of the key instruments for the NASA s Earth Observing System (EOS).MODIS ProtoFlight Model (PFM)was launched on-board the EOS Terra spacecraft on December 18,1999 and the MODIS Flight Model (FM-1)was launched on-board the EOS Aqua spacecraft on May 4, 2002.MODIS has 36 spectral bands with wavelengths ranging from 0.41 to 14.5 µm and

  9. Relative spectral response corrected calibration inter-comparison of S-NPP VIIRS and Aqua MODIS thermal emissive bands

    NASA Astrophysics Data System (ADS)

    Efremova, Boryana; Wu, Aisheng; Xiong, Xiaoxiong

    2014-09-01

    The S-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is built with strong heritage from EOS MODIS, and has very similar thermal emissive bands (TEB) calibration algorithm and on-board calibrating source - a V-grooved blackbody. The calibration of the two instruments can be assessed by comparing the brightness temperatures retrieved from VIIRS and Aqua MODIS simultaneous nadir observations (SNO) from their spectrally matched TEB. However, even though the VIIRS and MODIS bands are similar there are still relative spectral response (RSR) differences and thus some differences in the retrieved brightness temperatures are expected. The differences depend on both the type and the temperature of the observed scene, and contribute to the bias and the scatter of the comparison. In this paper we use S-NPP Cross-track Infrared Sounder (CrIS) data taken simultaneously with the VIIRS data to derive a correction for the slightly different spectral coverage of VIIRS and MODIS TEB bands. An attempt to correct for RSR differences is also made using MODTRAN models, computed with physical parameters appropriate for each scene, and compared to the value derived from actual CrIS spectra. After applying the CrIS-based correction for RSR differences we see an excellent agreement between the VIIRS and Aqua MODIS measurements in the studied band pairs M13-B23, M15-B31, and M16- B32. The agreement is better than the VIIRS uncertainty at cold scenes, and improves with increasing scene temperature up to about 290K.

  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. Tunable 6.8 W narrow bandwidth emission from a single-stripe continuous-wave broad-area laser diode in a simple external cavity.

    PubMed

    Jechow, Andreas; Raab, Volker; Menzel, Ralf

    2008-04-01

    An antireflection-coated broad-area laser diode with an emitter size of 400 microm x 1 microm and a chip length of 1500 microm is operated in a simple external cavity. For wavelength stabilization and to narrow the bandwidth a diffraction grating in a Littrow configuration is used. At an injection current of 9 A up to 6.8 W of optical output power and a resulting slope efficiency of 0.8 W/A could be achieved. Further, the bandwidth could be narrowed to 100 pm (FWHM), and a tuning range of 40 nm around 976 nm was obtained. PMID:18382571

  12. Analysis of GeV-band ?-ray emission from supernova remnant RX J1713.7-3946

    NASA Astrophysics Data System (ADS)

    Federici, S.; Pohl, M.; Telezhinsky, I.; Wilhelm, A.; Dwarkadas, V. V.

    2015-05-01

    Context. RX J1713.7-3946 is the brightest shell-type supernova remnant (SNR) of the TeV ?-ray sky. Earlier Fermi-LAT results on low energy ?-ray emission suggested that, despite large uncertainties in the background determination, the spectrum is inconsistent with a hadronic origin. Aims: We update the GeV-band spectra using improved estimates for the diffuse Galactic ?-ray emission and more than double the volume of data. We further investigate the viability of hadronic emission models for RX J1713.7-3946. Methods: We produced a high-resolution map of the diffuse Galactic ?-ray background corrected for the HI self-absorption and used it in the analysis of more than five years worth of Fermi-LAT data. We used hydrodynamic scaling relations and a kinetic transport equation to calculate the acceleration and propagation of cosmic rays in SNR. We then determined spectra of hadronic ?-ray emission from RX J1713.7-3946, separately for the SNR interior and the cosmic-ray precursor region of the forward shock, and computed flux variations that would allow us to test the model with observations. Results: We find that RX J1713.7-3946 is now detected by Fermi-LAT with very high statistical significance, and the source morphology is best described by that seen in the TeV band. The measured spectrum of RX J1713.7-3946 is hard with index ? = 1.53 ± 0.07, and the integral flux above 500 MeV is F = (5.5 ± 1.1) × 10-9 photons cm-2 s-1. We demonstrate that scenarios based on hadronic emission from the cosmic-ray precursor region are acceptable for RX J1713.7-3946, and we predict a secular flux increase at a few hundred GeV at the level of around 15% over ten years, which may be detectable with the upcoming Cherenkov Telescope Array (CTA) observatory.

  13. Valence band states and polarized optical emission from nonpolar and semipolar III–nitride quantum well optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Zhao, Yuji; Farrell, Robert M.; Wu, Yuh-Renn; Speck, James S.

    2014-10-01

    Nonpolar and semipolar III–nitride quantum wells (QWs) and devices have been extensively studied due to their unique valence band (VB) structure and polarized optical emission. Unlike conventional c-plane oriented III–nitride QWs, the low crystal symmetry and unbalanced biaxial stress in nonpolar and semipolar QWs separates the topmost VBs and gives rise to polarized optical emission. Since the first experimental reports on nonpolar devices, research on this topic has progressed very rapidly and has covered nonpolar m-plane and a-plane QWs and devices as well as semipolar (11\\bar{2}2), (20\\bar{2}1), and (20\\bar{2}\\bar{1}) QWs and devices. Issues such as strain, plane inclination angle (with respect to the c-plane), indium composition, temperature, and their impact on QW VB structure and device performance have been extensively studied. In this paper we review the physical background and theoretical analysis of the VB states and polarized optical emission of nonpolar and semipolar structures and discuss their potential impacts on optoelectronic devices. Experimental results for nonpolar and semipolar light-emitting diodes and laser diodes will be covered along with additional discussions on the potential applications and challenges related to their unique physical properties.

  14. Extreme Emission Line Galaxies in CANDELS: Broad-Band Selected, Star-Bursting Dwarf Galaxies at z>1

    E-print Network

    van der Wel, A; 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; Dickinson, M; Salmon, B; Kocevski, D F de Mello D D; Lai, K; Grogin, N A; Rodney, S A; Guo, Yicheng; McGrath, E G; Lee, K -S; Calvo, G B; Huang, K -H

    2011-01-01

    We identify an abundant population of extreme emission line galaxies (EELGs) 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 EELG 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 rest-frame equivalent widths ~1000\\AA -- in the four candidates that have HST/WFC3 grism observations, we conclude that these objects are dwarf galaxies with ~10^8 Msol in stellar mass, undergoing an enormous starburst phase with M*/(dM*/dt) of only ~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 (3.7 x 10^-4 Mpc^-3) can produce in ~4 Gyr much of the stellar mass density that is presently contained in 10^8-10^9 Mso...

  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. 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.

  17. Integrating broad-band high-fidelity acoustic emission sensors and array processing to study drying shrinkage cracking in concrete

    NASA Astrophysics Data System (ADS)

    McLaskey, Gregory C.; Glaser, Steven D.; Grosse, Christian U.

    2007-04-01

    Array processing of seismic data provides a powerful tool for source location and identification. For this method to work to its fullest potential, accurate transduction of the unadulterated source mechanism is required. In our tests, controlled areas of normal-strength concrete specimens were exposed to a low relative humidity at an early age to induce cracking due to drying shrinkage. The specimens were continuously monitored with an array of broad-band, high-fidelity acoustic emission sensors contrived in our laboratory in order to study the location and temporal evolution of drying shrinkage cracking. The advantage of the broadband sensors (calibration NIST-traceable) compared to more traditional acoustic emission sensors is that the full frequency content of the signals are preserved. The frequency content of the signals provides information about the dispersion and scattering inherent to the concrete, and the full unadulterated waveforms provide insight into the micromechanisms which create acoustic emissions in concrete. We report on experimental and analytical methods, event location and source mechanisms, and possible physical causes of these microseisms.

  18. 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.

  19. Annealing effect on the near-band edge emission of ZnO

    NASA Astrophysics Data System (ADS)

    Khomyak, V. V.; Slyotov, M. M.; Shtepliuk, I. I.; Lashkarev, G. V.; Slyotov, O. M.; Marianchuk, P. D.; Kosolovskiy, V. V.

    2013-02-01

    ZnO thin films have been grown on the sapphire (?-Al2O3) substrates at the temperature of 250 °C by means of the direct current (DC) magnetron sputtering technique. The crystal structure and surface morphology of the deposited films were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). The optical transmission, reflection and luminescence spectra at 300 K were analyzed for both the as-grown and post-annealed ZnO films. Using the ?-modulation method gives the possibility to reveal the main features of the energy band structure and the nature of the radiative transitions causing the ultraviolet (UV) luminescence.

  20. 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

  1. The electrosphere of macroscopc ""nuclei"": diffuse emissions in the MeV band from dark antimatter

    SciTech Connect

    Forbes, Michael Mcneil [Los Alamos National Laboratory; Lawson, Kyle [CANADA; Zhitnitsky, Ariel R [CANADA

    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.

  2. Stimulated emission within the exciplex band by plasmonic-nanostructured polymeric heterojunctions.

    PubMed

    Zhang, Xinping; Li, Hongwei; Wang, Yimeng; Liu, Feifei

    2015-03-19

    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. PMID:25757393

  3. Effects of Phonon Coupling and Free Carriers on Band-edge Emission at Room Temperature in n-type ZnO Crystals

    SciTech Connect

    Giles, N. C. [West Virginia University; Xu, Chunchuan [West Virginia University; Callahan, M. J. [Air Force Research Laboratory; Wang, Buguo [Air Force Research Laboratory; Neal, John S [ORNL; Boatner, Lynn A [ORNL

    2006-01-01

    Room-temperature photoluminescence has been studied in n-type bulk ZnO crystals representing three different growth methods and having free-carrier concentrations (n) ranging from 10{sup 13} to 10{sup 18} cm{sup -3}. The near-band-edge emission has both free-exciton and free-exciton-phonon contributions, with the strength of the phonon coupling dependent on sample defect concentrations. Band-gap shrinkage effects are used to explain a decrease in emission energy for the higher n values. Band filling and band nonparabolicity are predicted to be important for n>10{sup 19} cm{sup -3}. At 300 K, in the absence of free carriers, the free-exciton energy is 3.312{+-}0.004 eV.

  4. 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.

  5. 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

  6. 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].

  7. 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. [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan (China); Cheng, S.-C. [Department of Physics, Chinese Culture University, Taipei, Taiwan (China); Hsieh, W.-F. [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan (China); Institute of Electro-Optical Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China)

    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.

  8. Assessment of the NPP VIIRS RVS for the thermal emissive bands using the first pitch maneuver observations

    NASA Astrophysics Data System (ADS)

    Wu, A.; Xiong, X.; Chiang, K.; Sun, C.

    2012-09-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) is a key sensor carried on Suomi NPP (National Polar-orbiting Partnership) satellite (http://npp.gsfc.nasa.gov/viirs.html) (launched in October 2011). VIIRS sensor design draws on heritage instruments including AVHRR, OLS, SeaWiFS and MODIS. It has on-board calibration components including a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) for the reflective solar bands (RSB), a V-groove blackbody for the thermal emissive bands (TEB), and a space view (SV) port for background subtraction. These on-board calibrators are located at fixed scan angles. The VIIRS response versus scan angle (RVS) was characterized prelaunch in lab ambient conditions and is currently used to characterize the on-orbit response for all scan angles relative to the calibrator scan angle (SD for RSB and blackbody for TEB). Since the RVS is vitally important to the quality of calibrated radiance products, several independent studies were performed to analyze the prelaunch RVS measurement data. A spacecraft level pitch maneuver was scheduled during the first three months of intensive Cal/Val. The NPP pitch maneuver provided a rare opportunity for VIIRS to make observations of deep space over the entire range of scan angles, which can be used to characterize the TEB RVS. This study will provide our analysis of the pitch maneuver data and assessment of the derived TEB RVS. A comparison between the RVS determined by the pitch maneuver observations and prelaunch lab tests will be conducted for each band, detector, and half angle mirror (HAM) side.

  9. Effect of annealing on lattice strain and near-band-edge emission of ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Babikier, Musbah; Wang, Jinzhong; Wang, Dunbo; Li, Qian; Sun, Jianming; Yan, Yuan; Wang, Wenqi; Yu, Qingjiang; Jiao, Shujie; Gao, Shiyong; Li, Hongtao

    2014-07-01

    The effect of air and oxygen annealing on the structural and the optical properties of hydrothermally synthesized ZnO nanorods was investigated. After hydrothermal synthesis, the resulting ZnO nanorods were annealed in air and under an oxygen atmosphere at 370°C for 1 h. X-ray diffraction results revealed that the oxygen-annealed nanorods possessed high crystallinity with a hexagonal-wurtzite crystal structure in the (002) plane. Evaluation of strain showed a tensile lattice strain of 0.426% resulting from oxygen annealing. The photoluminescence measurements showed that the relative intensity ratio of the near-band-edge emission (NBE) to the green emission ( I NBE / I GE ) increased from ~2.6 for the as-grown ZnO nanorods to ~68.7 when the nanorods were annealed under oxygen. After annealing, a red shift of ~30 and ~44 meV in the NBE was observed for the nanorods that were annealed in air and under oxygen, respectively. This shift is attributed to the interaction between the neutral acceptors and the adsorbed oxygen atoms.

  10. Computational complexity of narrow band and wide band channel simulators

    Microsoft Academic Search

    R. Parra-Michel; V. Y. Kontorovitch; A. G. Orozco-Lugo; M. Lara

    2003-01-01

    Some questions such as: is it convenient to simulate channel realizations with the sum of sinusoids or with the filtering approach, are addressed in this work in order to provide a guide on which algorithms and in what situations should be used in the development of channel simulators. The conclusions presented are gathered from the comparison of the methods proposed

  11. DAY-SIDE z'-BAND EMISSION AND ECCENTRICITY OF WASP-12b

    SciTech Connect

    Lopez-Morales, Mercedes; Rogers, Justin C. [Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Coughlin, Jeffrey L. [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); Sing, David K. [Astrophysics Group, School of Physics, University of Exeter, Stocker Road, Exeter, Ex4 4QL (United Kingdom); Burrows, Adam; Spiegel, David S. [Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, NJ 08544 (United States); Apai, Daniel [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Adams, Elisabeth R., E-mail: mercedes@dtm.ciw.ed [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    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.

  12. Day-side z'-band Emission and Eccentricity of WASP-12b

    NASA Astrophysics Data System (ADS)

    López-Morales, Mercedes; Coughlin, Jeffrey L.; Sing, David K.; Burrows, Adam; Apai, Dániel; Rogers, Justin C.; Spiegel, David S.; Adams, Elisabeth R.

    2010-06-01

    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+0.0072 -0.0061, consistent with an orbital eccentricity of |ecos ?| = 0.016+0.011 -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. Based on observations collected with the Apache Point Observatory 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium (ARC).

  13. Comparison of Natural Narrow-banded Emissions and Sounder Stimulated Resonances In The Magnetospheres of Jupiter and The Earth (ulysses and Image Spacecraft)

    Microsoft Academic Search

    V. A. Osherovich; J. Fainberg; R. F. Benson; R. MacDowall

    2002-01-01

    The sounder stimulated resonances observed by Ulysses in JupiterSs Io torus re- vealed a spectrum of frequencies which has been interpreted in terms of Dn reso- nances together with electron plasma frequency fpe and Bernstein Qn resonances in order to determine the electron density and magnetic field strength (Osherovich et al. 1993; Benson et al. 1997). The presence of Dn

  14. Comparison of natural narrow-banded emissions and sounder stimulated resonances in the magnetosphere of Jupiter observed with the Ulysses spacecraft

    Microsoft Academic Search

    J. Fainberg; V. A. Osherovich; R. F. Benson; R. J. Macdowall

    2004-01-01

    Summary form only given. The sounder stimulated resonances observed by Ulysses in Jupiter's lo torus revealed a spectrum of frequencies which has been interpreted in terms of Dn resonances together with the electron plasma frequency fpe and Bernstein-mode resonances in order to determine the electron density and magnetic field strength. The presence of Dn resonances (cylindrical eigenmodes with frequencies proportional

  15. Controllable time dependent and dual band emission infrared source to test missile warning systems in flight

    NASA Astrophysics Data System (ADS)

    Cabib, Dario; Davidzon, Larry; Gil, Amir

    2008-10-01

    Proliferation and technological progress of Mid Wave Infrared (MWIR) sensors for Missile Warning Systems (MWS)1,2 and increased sophistication of countermeasures require demanding in-flight testing. The IR sensors are becoming more sensitive for longer range of detection, the spatial resolution is improving for better target detection and identification, spectral discrimination is being introduced for lower False Alarm Rate (FAR), and the imaging frame rate is increasing for faster defensive reaction. As a result, testing a complex MWS/countermeasure system performance before deployment requires ever more realistic simulation of the threats in their natural backgrounds, and faster measurement of the radiometric output, directionality and time response of the countermeasures. In a previous paper3 we have described a system (IRTS or Infrared Threat Stimulator) we developed to test missile warning systems (MWS) mounted on an aircraft. The IRTS is placed in the field and projects a time dependent infrared beam toward the flying aircraft. The time dependent intensity of the beam simulates the infrared emittance of an approaching missile in the 3 to 5 micron spectral range as sensed by an MWS system. Now we have developed a new system based on the IRTS concept allowing the user to separately control the time profiles of two different infrared ranges independently within the 3 to 5 micron range. This is important because MWS instrumentation now has higher spectral discrimination capability in order to be more missile-specific and less prone to be confused by clutter and background signals. In this paper we describe the new dual band IRTS system and its capability (or Dual Color IRTS, DCIRTS).

  16. The emissivity of foam-covered water surface at L-band: theoretical modeling and experimental results from the FROG 2003 field experiment

    Microsoft Academic Search

    Adriano Camps; Mercè Vall-llossera; Ramón Villarino; Nicolas Reul; Bertrand Chapron; Ignasi Corbella; Núria Duffo; Francesc Torres; Jorge José Miranda; Roberto Sabia; Alessandra Monerris; Rubén Rodríguez

    2005-01-01

    Sea surface salinity can be measured by microwave radiometry at L-band (1400-1427 MHz). This frequency is a compromise between sensitivity to the salinity, small atmospheric perturbation, and reasonable pixel resolution. The description of the ocean emission depends on two main factors: (1) the sea water permittivity, which is a function of salinity, temperature, and frequency, and (2) the sea surface

  17. 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. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)] [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    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.

  18. 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.

  19. OBSERVATIONS OF THE NEAR- TO MID-INFRARED UNIDENTIFIED EMISSION BANDS IN THE INTERSTELLAR MEDIUM OF THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Mori, Tamami I.; Sakon, Itsuki; Onaka, Takashi; Ohsawa, Ryou [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Kaneda, Hidehiro [Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Umehata, Hideki, E-mail: morii@astron.s.u-tokyo.ac.jp, E-mail: isakon@astron.s.u-tokyo.ac.jp, E-mail: onaka@astron.s.u-tokyo.ac.jp [Institute of Astronomy, Graduate School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

    2012-01-01

    We present the results of near- to mid-infrared slit spectroscopic observations (2.55-13.4 {mu}m) of the diffuse emission toward nine positions in the Large Magellanic Cloud with the infrared camera on board AKARI. The target positions are selected to cover a wide range of the intensity of the incident radiation field. The unidentified infrared bands at 3.3, 6.2, 7.7, 8.6, and 11.3 {mu}m are detected toward all the targets and ionized gas signatures; hydrogen recombination lines and ionic forbidden lines are detected toward three of them. We classify the targets into two groups: those without the ionized gas signatures (Group A) and those with the ionized signatures (Group B). Group A includes molecular clouds and photodissociation regions, whereas Group B consists of H II regions. In Group A, the band ratios of I{sub 3.3{mu}m}/I{sub 11.3{mu}m}, I{sub 6.2{mu}m}/I{sub 11.3{mu}m}, I{sub 7.7{mu}m}/I{sub 11.3{mu}m}, and I{sub 8.6{mu}m}/I{sub 11.3{mu}m} show positive correlation with the IRAS and AKARI colors, but those of Group B do not follow the correlation. We discuss the results in terms of the polycyclic aromatic hydrocarbon (PAH) model and attribute the difference to the destruction of small PAHs and an increase in the recombination due to the high electron density in Group B. In the present study, the 3.3 {mu}m band provides crucial information on the size distribution and/or the excitation conditions of PAHs and plays a key role in the distinction of Group A from B. The results suggest the possibility of the diagram of I{sub 3.3{mu}m}/I{sub 11.3{mu}m} versus I{sub 7.7{mu}m}/I{sub 11.3{mu}m} as an efficient diagnostic tool to infer the physical conditions of the interstellar medium.

  20. Observation of an intermediate band in Sn-doped chalcopyrites with wide-spectrum solar response.

    PubMed

    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 (CuGaS(2)) and ~0.8 eV (CuInS(2)) 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

  1. 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

  2. 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.

  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. Enhanced free exciton and direct band-edge emissions at room temperature in ultrathin ZnO films grown on Si nanopillars by atomic layer deposition.

    PubMed

    Chang, Yuan-Ming; Shieh, Jiann; Chu, Pei-Yuan; Lee, Hsin-Yi; Lin, Chih-Ming; Juang, Jenh-Yih

    2011-11-01

    Room-temperature ultraviolet (UV) luminescence was investigated for the atomic layer deposited ZnO films grown on silicon nanopillars (Si-NPs) fabricated by self-masking dry etching in hydrogen-containing plasma. For films deposited at 200 °C, an intensive UV emission corresponding to free-exciton recombination (~3.31 eV) was observed with a nearly complete suppression of the defect-associated broad visible range emission peak. On the other hand, for ZnO films grown at 25 °C, albeit the appearance of the defect-associated visible emission, the UV emission peak was observed to shift by ~60 meV to near the direct band edge (3.37 eV) recombination emission. The high-resolution transmission electron microscopy (HRTEM) showed that the ZnO films obtained at 25 °C were consisting of ZnO nanocrystals with a mean radius of 2 nm embedded in a largely amorphous matrix. Because the Bohr radius of free-exictons in bulk ZnO is ~2.3 nm, the size confinement effect may have occurred and resulted in the observed direct band edge electron-hole recombination. Additionally, the results also demonstrate order of magnitude enhancement in emission efficiency for the ZnO/Si-NP structure, as compared to that of ZnO directly deposited on Si substrate under the same conditions. PMID:21967063

  5. Infrared emission-line galaxies associated with damped Lyman-alpha and strong metal absorber redshifts

    Microsoft Academic Search

    F. Mannucci; D. Thompson; S. V. W. Beckwith; G. M. Williger

    1998-01-01

    Eighteen candidates for emission line galaxies were discovered in a\\u000anarrow-band infrared survey that targeted the redshifts of damped Lyman-alpha\\u000aor metal lines in the spectra of quasars. The presence of emission lines is\\u000ainferred from the photometric magnitudes in narrow and broad band interference\\u000afilters, corresponding to H-alpha at redshifts of 0.89 (6 objects) and 2.4 (10\\u000aobjects), and

  6. Electronically controlled microwave band gap filter structures

    Microsoft Academic Search

    Michael J. Hill; Richard W. Ziolkowski; John Papapolymerou

    2001-01-01

    Microwave band gap structures (MBG) utilizing fixed defects have received much interest because of their ability to operate as narrow band filters. With the recent interest in reconfigurable wireless devices, the need for electronically controllable narrow band filters is on the rise. By altering the defects in an MBG crystal, the transmission properties of the crystal can be changed. Using

  7. A hybrid laser system consisting of a frequency-doubled, narrow-line-width, distributed-feedback dye laser oscillator and a high saturation-fluence Ce:LiCaAlF6 crystal amplifier

    NASA Astrophysics Data System (ADS)

    Hoa, D. Q.; Hung, N. D.; Moroe, J.; Takeyasu, N.; Imasaka, T.

    2003-05-01

    A tunable narrow-band picosecond dye laser emitting in the ultraviolet region was amplified using a Ce:LiCaAlF6 crystal pumped by the fourth-harmonic emission of a Nd:Y3Al5O12 laser. The single-pass gain obtained exceeded 2 in the spectral range of 288 to 297 nm.

  8. 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

  9. Characterization of tropical atmosphere through wide-band emission spectra acquired with a balloon-borne uncooled FTS spectroradiometer

    NASA Astrophysics Data System (ADS)

    Bianchini, Giovanni; Palchetti, Luca; Carli, Bruno; Cortesi, Ugo; Del Bianco, Samuele

    2007-10-01

    On June 30th, 2005 the REFIR-PAD (Radiation Explorer in the Far InfraRed-Prototype for Application and Development) Fourier transform spectroradiometer performed the first wide-band spectral characterization of the top-of-atmosphere emitted radiation in the far-infrared with an uncooled instrument. The nadir emitted radiance has been measured down to 100 cm -1, thus covering a spectral interval that, until now, was nearly unexplored, and up to 1400 cm -1, including the well characterized atmospheric window region, in which it is possible to perform comparison and intercalibration with operative instruments. The measurements were performed at an altitude of 34 km, from a stratospheric balloon launched in tropical region, near Teresina, Brazil). The acquired spectra have a spectral resolution of 0.5 cm -1. It should be noted that despite the operating spectral range extending to the far-infrared region, REFIR-PAD does not require any cooled components, thanks to the use of pyroelectric detectors and an optical scheme that compensates for the instrument self-emission. This work shows the results of the analysis of the spectra, focusing on the far infrared portion of the atmospheric emitted radiance. The retrieval of the vertical profiles of water vapour and temperature during the flight is presented. The vertical resolution of the retrieval is 2 km in the upper troposphere-lower stratosphere (UTLS) region, and lower at higher altitudes. The comparison with ECMWF for validation is also shown. Besides the characterization of temperature and water vapour, from the analysis of the emitted radiance useful information can be gathered about cloud and aerosol contribution to radiation budget.

  10. 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. [Research Institute, National Printing Bureau of Japan, Odawara, Kanagawa 256-0816 (Japan); Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164-2814 (United States)

    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 +}.

  11. Effect of line-mixing on the emissions in the infrared CO2 bands in the middle and upper atmosphere of Earth

    NASA Astrophysics Data System (ADS)

    Ogibalov, Vladimir

    Radiative transfer in the infrared (IR) ro-vibrational bands of CO2 molecules under non-local thermodynamic equilibrium (NLTE) conditions is an important factor in establishing the global heat balance, structure, and dynamical properties of the mesosphere and lower thermosphere (MLT) of Earth. Moreover, the emissions in the IR bands of CO2 are used for remote sensing of the kinetic temperature and the CO2 abundance in the MLT altitude interval. These reasons require developing both more sophisticated models for estimating the values of non-equilibrium populations of the excited vibrational states of CO2 in the MLT and more detailed radiative transfer schemes. The validity of estimating the cooling rate in the 15 µm CO2 band depends on various input data used. In particular, spectroscopic parameters and a shape of absorption coefficient adopted for lines of the IR CO2 bands are of great importance. Till present time in the NLTE models developed to calculate IR emissions in the CO2 bands, it has been supposed that the absorption coefficient in the band is a simple sum of absorption coefficients of lines included at the given frequency and that the spectral shape of the absorption coefficient in every line is described by the Voigt function. However, it is known, when lines overlap in frequency (especially, in Q-branches of CO2 bands), the spectral band shape calculated according to this approximation could deviate to a large extent from the experimental one due to the effect of line-mixing (LM). This makes the LM-effect be potentially important for solving the NLTE problem of the CO2 bands. In the present study, the current version of computer code realizing the NLTE model for the IR emissions of CO2 in the MLT [1-2] has been further improved to incorporate the LMeffect. The Adjusted Branch Coupling method has been applied to simulate the experimental shape of the absorption coefficient within the spectral interval of the 15 µm band [3]. For a set of atmospheric parameter models, the reference solutions of the NLTE problem of the CO2 emissions in the Earth atmosphere have been obtained with and without taking into account for the line-mixing. Only small differences (less than 3 per cent within the 20-160 km altitude interval) due to the LM-effect both on the values of the populations of vibrational states excited in the CO2 (? 1 ) and CO2(? 2 ) modes and on the values of the cooling rate in the 15 µm CO2 band were found out. The reasons of such negligible influence of the LM-effect are discussed. Also, the spectra of the limb radiance of the MLT in the 15 µm spectral interval have been simulated with different frequency resolution. For the case of high resolution (less than 0.01 cm-1 ), the spectral intervals with significant influence due to the LM-effect on the values of the limb radiance with target heights above 70 km have been revealed. The research was partly supported by the German Academic Exchange Service (DAAD), grant A/07/09380. [1] Shved G.M., Kutepov A.A., and Ogibalov V.P. // JASTP, v. 60, pp.289-314, 1998. [2] Ogibalov V.P., Kutepov A.A., and Shved G.M. // JASTP, v. 60, pp.315-329, 1998. [3] Tonkov M.V., et al. // JQSRT , v. 56, p. 783, 1996.

  12. Discrete Electronic Bands in Semiconductors and Insulators: Potential High-Light-Yield Scintillators

    NASA Astrophysics Data System (ADS)

    Shi, Hongliang; Du, Mao-Hua

    2015-05-01

    Bulk semiconductors and insulators typically have continuous valence and conduction bands. Here, we show that valence and conduction bands of a multinary semiconductor or insulator can be split to narrow discrete bands separated by large energy gaps. This unique electronic structure is demonstrated by first-principles calculations in several quaternary elpasolite compounds, i.e., Cs2NaInBr6 , Cs2NaBiCl6 , and Tl2NaBiCl6 . The narrow discrete band structure in these quaternary elpasolites is due to the large electronegativity difference among cations and the large nearest-neighbor distances in cation sublattices. We further use Cs2NaInBr6 as an example to show that the narrow bands can stabilize self-trapped and dopant-bound excitons (in which both the electron and the hole are strongly localized in static positions on adjacent sites) and promote strong exciton emission at room temperature. The discrete band structure should further suppress thermalization of hot carriers and may lead to enhanced impact ionization, which is usually considered inefficient in bulk semiconductors and insulators. These characteristics can enable efficient room-temperature light emission in low-gap scintillators and may overcome the light-yield bottleneck in current scintillator research.

  13. Are 2-micron absorptions and 11-micron emissions of M stars related. [solor and spectral band correlations with boundary temperature

    NASA Technical Reports Server (NTRS)

    Fay, T. D., Jr.

    1974-01-01

    Three properties of M stars are compared: (1) /3.5/ - /11/ colors, (2) two measures of 2.3-micron band absorption, and (3) two measures of 1.9-micron band absorption. We find that the 2.3-micron bands of 21 M giants and supergiants correlate with /3.5/ - /11/ colors at better than 99 per cent confidence. A comparable relation exists between the mean 1.9-micron bands and /3.5/ - /11/ colors of 23 M giants and Miras. The sum of the 1.9-micron + 2.3-micron band intensities correlates with /3.5/ - /11/ color at better than the 99.8 per cent level for 31 M stars. These relations are consistent with both CO and H2O cooling of M star boundaries. Binaries and Ia supergiants appear to depart from these relations.

  14. 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. (California Univ., Berkeley (USA); Lick Observatory, Santa Cruz, CA (USA); Search for Extraterrestrial Intelligence Institute, Los Altos, CA (USA))

    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.

  15. 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.

  16. Optical Spectrograph and InfraRed Imaging System (OSIRIS) observations of mesospheric OH A2Sigma+-X2Pi 0-0 and 1-1 band resonance emissions

    Microsoft Academic Search

    R. L. Gattinger; D. A. Degenstein; E. J. Llewellyn

    2006-01-01

    Although only a minor species, the OH molecule plays an important role in the photochemical control of mesospheric ozone density and has been the target of a number of observational programs, principally through the OH A2Sigma+-X2Pi 0-0 band emission at 308 nm. This emission band arises from solar resonance fluorescence excitation of OH X2Pi ground state molecules, and its observation

  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

    NASA Astrophysics Data System (ADS)

    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.

  18. 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

  19. 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.

  20. Nonlinear regression analysis of field emission data 

    E-print Network

    Barry, Scott Wilson

    1992-01-01

    current on anode cath- ode spacing. Field emitters also have a narrower electron energy spread compared to thermionic emitters, and so have been used to improve Scanning Electron Microscope resolution. Finally, due to the possibility of almost pure.... For tungsten and molybdenum, band structure seems to be important only for the (100) and (110) directions. In the case of W (100), a deviation from free electron theory in the total electron energy distribution consisting of an enhanced emission peak . 35 e...