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1

The emission of narrow-band Jovian kilometric radiation  

NASA Astrophysics Data System (ADS)

A model based on the nonlinear coupling of electrostatic plasma waves is proposed to explain the emission of the narrow-band Jovian kilometric radiation (nKOM) observed by the Voyager spacecraft. It is shown that upper-hybrid branch electrostatic waves propagating through the inhomogeneities in the outer periphery of the Io plasma torus can attain the proper geometry for localized upconversion interactions leading to pump depletion. Plasma waves propagating into a weak density gradient and reflected at the critical layer interact with the incident waves leading to the electromagnetic emission, which is beamed at large angles with respect to the background magnetic field. In general, both L-O and R-X mode waves can be generated. The observed power and net polarization (L-O) are consistent with pump depletion of electrostatic waves at a level of about 10 mV/m. A possible excitation mechanism for the electrostatic waves is also discussed.

Fung, S. F.; Papadopoulos, K.

1987-08-01

2

Source characteristics of Jovian narrow-band kilometric radio emissions  

NASA Astrophysics Data System (ADS)

New observations of Jovian narrow-band kilometric (nKOM) radio emissions were made by the Unified Radio and Plasma Wave (URAP) experiment on the Ulysses spacecraft during the Ulysses-Jupiter encounter in early February 1992. These observations have demonstrated the unique capability of the URAP instrument for determining both the direction and polarization of nKOM radio sources. An important result is the discovery that nKOM radio emission originates from a number of distinct sources located at different Jovian longitudes and at the inner and outermost regions of the Io plasma torus. These sources have been tracked for several Jovian rotations, yielding their corotational lags, their spatial and temporal evolution, and their radiation characteristics at both low latitudes far from Jupiter and at high latitudes near the planet. Both right-hand and left-hand circularly polarized nKOM sources were observed. The polarizations observed for sources in the outermost regions of the torus seem to favor extraordinary mode emission.

Reiner, M. J.; Fainberg, J.; Stone, R. G.; Kaiser, M. L.; Desch, M. D.; Manning, R.; Zarka, P.; Pedersen, B.-M.

1993-07-01

3

Simultaneous But Different Narrow-Band Sound Emissions by a Captive Eastern Pacific Pilot Whale, Globicephala Scammoni.  

National Technical Information Service (NTIS)

A captive female eastern Pacific pilot whale, Globicephala scammoni, was found to produce two different narrow-band sounds simultaneously. The observation confirms an earlier report of a similar double narrow-band emission by a wild Mediterranean pilot wh...

M. C. Caldwell D. K. Caldwell

1969-01-01

4

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

SciTech Connect

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.

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

2009-06-19

5

Hybrid Semiconducting Polymer Dot-Quantum Dot with Narrow-Band Emission, Near-Infrared Fluorescence, and High Brightness  

PubMed Central

This communication describes a new class of semiconducting polymer nanoparticle-quantum dot hybrid with high brightness, narrow emission, near-infrared fluorescence, and excellent cellular targeting capability. Using this approach, we circumvented the current difficulty with obtaining narrow-band emission and near-infrared fluorescing semiconducting polymer nanoparticles, while combining the advantages of both semiconducting polymer nanoparticles and quantum dots. We further demonstrated the use of this new class of hybrid nanomaterial for effective and specific cellular and subcellular labeling without any noticeable nonspecific binding. This hybrid nanomaterial is anticipated to find use in a variety of in vitro and in vivo biological applications.

Chan, Yang-Hsiang; Ye, Fangmao; Gallina, Maria Elena; Zhang, Xuanjun; Jin, Yuhui; Wu, I-Che; Chiu, Daniel T.

2012-01-01

6

Hybrid semiconducting polymer dot-quantum dot with narrow-band emission, near-infrared fluorescence, and high brightness.  

PubMed

This communication describes a new class of semiconducting polymer nanoparticle-quantum dot hybrid with high brightness, narrow emission, near-IR fluorescence, and excellent cellular targeting capability. Using this approach, we circumvented the current difficulty with obtaining narrow-band-emitting and near-IR-fluorescing semiconducting polymer nanoparticles while combining the advantages of both semiconducting polymer nanoparticles and quantum dots. We further demonstrated the use of this new class of hybrid nanomaterial for effective and specific cellular and subcellular labeling without any noticeable nonspecific binding. This hybrid nanomaterial is anticipated to find use in a variety of in vitro and in vivo biological applications. PMID:22515545

Chan, Yang-Hsiang; Ye, Fangmao; Gallina, Maria Elena; Zhang, Xuanjun; Jin, Yuhui; Wu, I-Che; Chiu, Daniel T

2012-04-23

7

Searching for emission line and OB stars in Cl 1806-20 using a NIR narrow-band technique  

Microsoft Academic Search

We survey the environment of Cl 1806-20 using near-infrared narrow-band imaging to search for Brgamma features indicative of evolved massive stars. Using this technique, we successfully detect previously identified massive stars in the cluster. We detect no new emission line stars, establishing a firm upper limit on the number of Wolf Rayets and Luminous Blue Variables; however, we do find

Michelle L. Edwards; Reba M. Bandyopadhyay; Stephen S. Eikenberry; Valerie J. Mikles; Dae-Sik Moon

2011-01-01

8

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

NASA Astrophysics Data System (ADS)

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.

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

1994-01-01

9

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

10

Cluster survey of narrow band electrostatic emissions in the plasmasphere region.  

NASA Astrophysics Data System (ADS)

Several kinds of natural electrostatic emissions are observed in the outer plasmasphere (Christiansen et al 1978, Olsen et al 1987), in particular emissions related to the electron gyrofrequency (Hubbard and Birmingham 1978), classified as low 3/2 in the class 1a. The low 3/2 emissions have been routinely observed by WHISPER instrument in the plasmasphere region. These emissions are present as bandwidth electrostatic emissions. They are referred to as n(1.1) fce in this work. The Whisper instrument provides a good resolution on time and frequency and allow a fine spectral characterization of the frequency and intensity of these waves. Compared to the (n+1/2) fce emissions, the n(1.1) fce emissions are less intense, and present a high latitudinal extension. A statistical study of these emission using five years of data (2002-2007) is presented. The MLT dependence and the latitudinal extension of these emissions is investigated. The relative occurrence of the n(1.1) fce emissions is calculated, exploring the effect of the distance to the plasmapause in their observation. Finally, a test of the geomagnetic activity influence is presented via the variations of the DST index associated to the observations.

El-Lemdani Mazouz, F.; Décréau, P. M. E.; Rauch, J. L.; Grimald, S.; Vallières, X.; Kougblenou, S.; Trotignon, J. G.; Canu, P.; darrouzet, F.

2012-04-01

11

Swept Narrow Band Random on Random.  

National Technical Information Service (NTIS)

The implementation of swept narrow band random on random on the HP5451C Fourier Analyzer System and the HP5427A Vibration Control System is discussed. Up to five narrow bands of a dynamically changing narrow band random spectrum can be super-imposed on a ...

F. T. Mercer

1980-01-01

12

Narrow band gap amorphous silicon semiconductors  

Microsoft Academic Search

Disclosed is a narrow band gap amorphous silicon semiconductor comprising an alloy of amorphous silicon and a band gap narrowing element selected from the group consisting of Sn, Ge, and Pb, with an electron donor dopant selected from the group consisting of P, As, Sb, Bi and N. The process for producing the narrow band gap amorphous silicon semiconductor comprises

A. Madan; A. H. Mahan

1985-01-01

13

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)

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.

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

14

Electrical Conductivity in Narrow Energy Bands  

Microsoft Academic Search

The electrical conductivity for a system of electrons described by the single-band Hubbard Hamiltonian is studied. An expression for the electrical conductivity that is applicable in the narrow-band regime, i.e., the bandwidth Delta, much smaller than intra-atomic Coulomb repulsion I is derived. It is shown that the conductivity vanishes at T=0 to first order in DeltaI for one electron per

Robert A. Bari; David Adler; Robert V. Lange

1970-01-01

15

Narrow-Band Nonlinear Sea Waves  

Microsoft Academic Search

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

M. Aziz Tayfun

1980-01-01

16

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

PubMed Central

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.

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

2012-01-01

17

Target detection against narrow band noise backgrounds.  

PubMed

We studied the detectability of narrow band random noise targets embedded in narrow band random noise backgrounds as a function of differences in center frequency, spatial frequency bandwidth and orientation bandwidth between target and the immediately adjacent background. Unlike most target detection experiments the targets were not added to the background; they replaced the underlying background texture. Simulations showed that target detection probabilities could be accounted for by a simple transformation on the summed outputs of a two layer filter model similar to the complex channels model proposed by Graham, Beck and Sutter (Graham, N., Beck, J., & Sutter, A. (1992). Vision Research, 32, 719-743). Subsequently, the model was tested on the detection of camouflaged vehicle targets with encouraging results. PMID:10343801

Cannon, M W; Reese, G J; Fullenkamp, S C

1999-06-01

18

Narrow-band microwave filter design  

Microsoft Academic Search

In this article, Dishal's concepts, EM simulation, and the port-tuning concept are combined as a powerful procedure for narrow-band filter design. When applied to an EM-based filter prototype, port tuning gives a direct indication of the magnitude and direction of the tunings needed to correct coupling errors and resonator frequency errors. An EM-based filter prototype potentially captures all the physics

Daniel G. Swanson

2007-01-01

19

Synchrotron studies of narrow band materials  

SciTech Connect

Objective was to determine the single-particle electronic structure of selected narrow band materials in order to understand the relation between their electronic structures and novel low energy properties, such as mixed valence, heavy Fermions, Kondo effect, insulator-metal transitions, non-Fermi liquid behavior, and high-temperature superconductivity. This program supports photoemission spectroscopy (PES) at various synchrotrons. The progress is reported under the following section titles: ZSA (Zaanen-Sawatzky-Allen) systematics and I-M transitions in 3d transition metal oxides, insulator-metal transitions in superconducting cuprates, Fermi liquid and non-Fermi liquid behavior in angular resolved PES lineshapes, heavy-Fermion and non-Fermi liquid 5f electron systems, and Kondo insulators.

Allen, J.W.

1993-01-01

20

Polarized Thermal Emission from Narrow Tungsten Filaments  

Microsoft Academic Search

FROM experimental work carried out by Fresnel many years ago and a theoretical investigation made by K. Schwarzschild1, it is well known that light transmitted through a narrow slit is more or less polarized. Though conditions are rather different in the case of thermal emission from a narrow filament the idea has occurred to me that polarized emission may be

Yngve Öhman

1961-01-01

21

One structure for efficient narrow-band bandpass FIR filters  

Microsoft Academic Search

This paper presents a narrow-band bandpass FIR filter design with a small number of multipliers per output sample (NMPS). The proposed method is based on the use of the pipelining\\/interleaving (PI) technique within a quadrature modulation structure, where only one narrow-band lowpass filter is required. In order to reduce the NMPS, the narrow-band lowpass filter is designed with an interpolated

G. Jovanovic-Dolecek; J. Diaz-Carmona

2002-01-01

22

Narrow-Band, Slowly Varying Decimetric Radiation from the Dwarf M Flare Star YZ Canis Minoris.  

National Technical Information Service (NTIS)

Narrow-band slowly varying microwave radiation has been detected from the dwarf M star YZ Canis Minoris at frequencies near 1465 MHz. This quiescent, or nonflaring, emission cannot be attributed to gyroresonant radiation from coronal loops; the loops woul...

K. R. Lang R. F. Willson

1986-01-01

23

A novel implementation for narrow-band FIR digital filters  

Microsoft Academic Search

In an earlier paper Crochiere and Rabiner [1] discuss the theory of using finite impulse response (FIR) digital filters for signal decimation, interpolation, and filtering. In this paper we expand on the ideas presented in the earlier paper on implementing narrow-band designs efficiently. It is shown how, using the techniques of decimation and interpolation, a desired narrow-band filter can be

LAWRENCE R. RABINER; RONALD E. CROCHIERE

1975-01-01

24

Microwave Band-Stop Filters with Narrow Stop Bands  

Microsoft Academic Search

Band-stop filters can be used to eliminate a band of frequencies, or to separate such a band from other frequencies; if properly designed, the insertion loss at frequencies outside the stop-band can be minimized. The filters considered here have stop-band bandwidths up to a few per cent, and equiripple or maximally flat characteristics in the passband. Design formulas are presented.

E. M. T. Jones; L. Young; G. L. Matthaei

1962-01-01

25

The Narrow-Band Model and Semi-Conductor Theory  

ERIC Educational Resources Information Center

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

Tanner, B. K.

1976-01-01

26

Implementation of the weighted sum of gray gases model to a narrow band: Application and validity  

SciTech Connect

Modeling the nongray behavior of combustion gases, such as water vapor and carbon dioxide, is very important for calculating the radiative heat transfer in furnaces and boilers. Here, the weighted sum of gray gases model (WSGGM) is applied to narrow bands of water vapor for analyzing radiative heat transfer in nongray media. For a given narrow band, the band mean spectral emissivity is represented by a weighted sum of gray gas emissivities expressed in terms of absorption coefficients, weighting factors, absorbing gas density, and path length. Five types of temperature-versus-narrow band absorption coefficient relation are suggested, and comparisons between the modeled emissivity and that of the original narrow band model are made and shown at a few typical bands. Total and low-resolution spectral intensities at the boundary are obtained for uniform, parabolic, boundary-layer-type temperature and parabolic concentration profiles using the WSGGM with five gray gases. Results using the Curtis-Godson approximation are compared with the WSGGM computations for each narrow band. The results using the WSGGM show good agreement with the Curtis-Godson approximation results, and especially, two of the WSGGMs with wave number-dependent absorption coefficient show highly accurate results with a few percent error in the total wall heat flux. The WSGGMs with wave number-independent absorption coefficients are, however, more useful for total spectrum computation, with a slight sacrifice in the accuracy.

Kim, O.J.; Song, T.H. [Korea Advanced Inst. of Science and Technology, Kusong, Taejon (Korea, Republic of). Dept. of Mechanical Engineering

1996-12-01

27

Narrowing of Topological Bands due to Electronic Orbital Degrees Freedom  

Microsoft Academic Search

The fractional quantum Hall effect has been predicted to occur in the absence of magnetic fields and at high temperature in lattice systems that have flat bands with a nonzero Chern number. We demonstrate that orbital degrees of freedom in frustrated lattice systems lead to a narrowing of topologically nontrivial bands. This robust effect does not rely on fine-tuned long-range

Jörn W. F. Venderbos; Maria Daghofer; Jeroen van den Brink

2011-01-01

28

Narrow-band analysis of nonstationary processes  

NASA Astrophysics Data System (ADS)

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.

Robinson, P. M.; Marinucci, Domenico

29

A Narrow-band Survey of Protostellar Shock Activity  

NASA Astrophysics Data System (ADS)

Energetic outflows are a ubiquitous signpost of star formation, observed in young stars of all masses. In studies of the early stages of star formation, we strive both to understand the mechanical and chemical properties of gas within an outflow, and to characterize outflow interactions with the dense clouds in which they are embedded. To develop a complete model of the interactions between protostar, outflow, and natal molecular cloud, surveys of entire star forming clouds as well as detailed studies of individual outflows are required. We have conducted a near-infrared protostellar shock survey of 35 star-forming regions in the Galaxy, including both isolated, individual outflows as well as larger molecular clouds containing multiple outflows. We imaged these regions in near-infrared narrow-band emission lines of molecular hydrogen, [FeII], and Paschen beta with the refurbished 2MASS camera on the Steward Observatory 61-inch Kuiper telescope. In addition, we have obtained moderate resolution (R=3500) near-infrared spectra (using TripleSpec at the Apache Point Observatory) for some of the individual outflows. We use the complementary near-infrared spectroscopic and imaging data to characterize the physical properties of each outflow, including excitation temperatures, emission line velocities, and energetics, and to describe the feedback these outflows may have on their natal clouds.

Drosback, Meredith M.; Indebetouw, R.

2011-01-01

30

Biological effects of narrow band pulsed electric fields  

Microsoft Academic Search

This paper describes the process of narrow band pulsed electric fields (NPEFs) and its effect on mammalian cells. The NPEF consists of a pulse modulated sinusoidal wave (PMSW), which allows delivery of well-defined electric fields in terms of frequency, field strength and deposition energy to the biological systems. 100 mus long sinusoidal electric fields with a frequency of 0.02, 2

Sunao Katsuki; Naoyuki Nomura; Hideto Koga; Hidenori Akiyama; Ichiro Uchida; Shin-ichi Abe

2007-01-01

31

Narrow-Band Biphoton Generation near Atomic Resonance  

Microsoft Academic Search

Generating nonclassical light offers a benchmark tool for the fundamental research and potential applications in quantum optics. Conventionally, it has become a standard technique to produce the nonclassical light through the nonlinear optical processes occurring in nonlinear crystals. In this review we describe using cold atomic-gas media to generate such nonclassical light, especially focusing on narrow-band biphoton generation. Compared with

Shengwang Du; Jianming Wen; Morton H. Rubin

2008-01-01

32

Digital Radio Link: Wave Propagation Measurements Using Narrow Band Technique.  

National Technical Information Service (NTIS)

Measurements on a 34 M Bit, 7 GHz digital radio link with a linkhop of 56 km are described. Events with flat and frequency selective fading are presented and a method using narrow band measurements to evaluate frequency selective fading is outlined. By ma...

S. Nilsson L. Ladell

1984-01-01

33

Subwavelength structured narrow-band integrated optical grating filters  

SciTech Connect

A unique type of narrow band integrated optical filter is investigated based on embedding a subwavelength resonant grating structure within a planar waveguide. Current integrated narrow-band optical filters are limited by their size, density of devices that can be produced, overall performance, and ability to be actively altered for tuning and modulation purposes. In contrast, the integrated optical filters described in this work can have extremely narrow bandwidths--on the order of a few angstroms. Also, their compact size enables multiple filters to be integrated in a single high density device for signal routing or wavelength discrimination. Manipulating any of the resonant structure`s parameters will tune the output response of the filter, which can be used for modulation or switching applications.

Grann, E.B.; Holcomb, D.E.; Zuhr, R.A. [Oak Ridge National Lab., TN (United States); Moharam, M.G. [Univ. of Central Florida, Orlando, FL (United States). Center for Research and Education in Optics and Lasers

1998-01-01

34

Recovering physical properties from narrow-band photometry  

NASA Astrophysics Data System (ADS)

Our aim in this work is to answer, using simulated narrow-band photometry data, the following general question: What can we learn about galaxies from these new generation cosmological surveys? For instance, can we estimate stellar age and metallicity distributions? Can we separate star-forming galaxies from AGN? Can we measure emission lines, nebular abundances and extinction? With what precision? To accomplish this, we selected a sample of about 300k galaxies with good S/N from the SDSS and divided them in two groups: 200k objects and a template library of 100k. We corrected the spectra to z = 0 and converted them to filter fluxes. Using a statistical approach, we calculated a Probability Distribution Function (PDF) for each property of each object and the library. Since we have the properties of all the data from the STARLIGHT-SDSS database, we could compare them with the results obtained from summaries of the PDF (mean, median, etc). Our results shows that we retrieve the weighted average of the log of the galaxy age with a good error margin (? ? 0.1 - 0.2 dex), and similarly for the physical properties such as mass-to-light ratio, mean stellar metallicity, etc. Furthermore, our main result is that we can derive emission line intensities and ratios with similar precision. This makes this method unique in comparison to the other methods on the market to analyze photometry data and shows that, from the point of view of galaxy studies, future photometric surveys will be much more useful than anticipated.

Schoenell, W.; Cid Fernandes, R.; Benítez, N.; Vale Asari, N.

2013-05-01

35

Lasers without inversion (LWI) in Space: A possible explanation for intense, narrow-band, emissions that dominate the visible and\\/or far-UV (FUV) spectra of certain astronomical objects  

Microsoft Academic Search

The optical or far-UV (FUV) spectra of certain objects in Space are completely dominated by one or two spectrally narrow emission lines, strongly suggesting that laser action of some kind occurs in these objects. However, the electronic level structures of the atoms\\/ions producing these emissions preclude the possibility of maintaining population inversions on the electronic transitions involved. In lasers, gain

P. P. Sorokin; J. H. Glownia

2002-01-01

36

Narrow-band imaging and a search for planetary nebulae  

NASA Astrophysics Data System (ADS)

We summarize the results of narrow-band (H? and [\\O 3] lambda 5007 Angstroms) imaging of eight planetary nebulae taken during recent observing campaigns: We present the probably largest known PN, MWP 1, with a linear diameter of about 6 pc. We show first narrow-band images of He 2-437, MeWe 1-5, MeWe 1-8, MeWe 1-9, NGC 1360, and of - like we term them - the ``Galactic footballs'' A 43 and NGC 7094. We report about a search for planetary nebulae around eleven extremely hot (pre-) white dwarfs which had not been successful. Based on observations obtained at the German-Spanish Astronomical Center, Calar Alto, operated by the Max-Planck-Institut für Astronomie Heidelberg jointly with the Spanish National Commission for Astronomy and at the European Southern Observatory, La Silla, Chile.

Rauch, T.

1999-03-01

37

Error spectrum shaping in narrow-band recursive filters  

Microsoft Academic Search

The error introduced by zero memory quantizers can usually be modeled by an additive white noise component. By incorporating feedback and additional memory elements to these quantizers, it is possible to shape the error spectrum to advantage. Two simple error spectrum shaping quantizers are presented, one to be used with narrow-band low-pass filters and the other with high-pass filters. Simulation

Tran-Thong; Bede Liu

1977-01-01

38

Limits on neutrino oscillations in the Fermilab narrow band beam  

SciTech Connect

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.

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

39

Spectral narrowing of solid state lasers by narrow-band PTR Bragg mirrors  

NASA Astrophysics Data System (ADS)

Dramatic spectral narrowing of normally broad band lasers, Ti:Sapphire,Cr:LiSAF, and alexandrite was achieved by simply replacing the output mirror with a reflective, volumetric Bragg grating recorded in photo thermal refractive (PTR) glass. The output power of each laser was changed very slightly from that obtained using dielectric coated output mirrors with the same output coupling as the Bragg grating while spectral brightness increased by about three orders of magnitude.

Chung, T.; Rapaport, A.; Chen, Y.; Smirnov, V.; Hemmer, M.; Glebov, L. B.; Richardson, M. C.; Bass, M.

2006-06-01

40

Software tool for the design of narrow band band-pass filters  

Microsoft Academic Search

An efficient and versatile CAD tool for the design and synthesis of narrow band, band-pass microwave filters with generalized Chebyshev transfer function has been developed. The program allows transfer function zeros at prescribed positions to be synthesized. Thus, it is suitable for asymmetric response or self-equalized filters. The location of the zeros can be optimized in order to comply with

A. Garcia-Lamperez; M. Salazar-Palma; M. Padilla; I. Hidalgo-Carpintero

2001-01-01

41

Realization of narrow-band active RC-band-pass-filters  

Microsoft Academic Search

The signal flow graph active synthesis technique is discussed with respect to the obtainable quality of narrow band-pass filters. The applications of three band-pass resonator circuits are compared, and a new integrator circuit is presented. A procedure for variating filter bandwidths is examined and a 10th order band-pass is presented, which demonstrates that high quality can be achieved.

W. Rupp; A. Goldmann

1980-01-01

42

Observations of the Galaxy NGC 3077 in the Narrow-Band [s II] and H? Filters  

NASA Astrophysics Data System (ADS)

We present observations of the H I tidal arm near a dwarf galaxy NGC 3077 (member of the M81 galaxy group) in the narrow-band [S II] and H? filters. Observations were carried out in 2011 March with the 2 m RCC telescope at the NAO Rozhen, Bulgaria. Our search for possible supernova remnant candidates (identified as sources with enhanced [S II] emission relative to their H? emission) in this region yielded no sources of this kind. Nevertheless, we found a number of objects with significant H? emission that probably represent uncatalogued, low brightness H II regions.

Andjeli?, M.; Stavrev, K.; Arbutina, B.; Ili?, D.; Uroševi?, D.

2011-08-01

43

O2 atmospheric band measurements with WINDII: performance of a narrow-band filter/wide-angle Michelson combination in space  

NASA Astrophysics Data System (ADS)

Among the emissions viewed by the wind imaging interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS) are selected lines in the (0 - 0) transition of the O(subscript 2) atmospheric band. These lines are viewed simultaneously using a narrow band filter/wide- angle Michelson interferometer combination. The narrow band filter is used to separate the lines on the CCD (spectral-spatial scanning) and the Michelson used to modulate the emissions so that winds and rotational temperatures may be measured from the Doppler shifts and relative intensities of the lines. In this report this technique is outlined and the on-orbit behavior since launch summarized.

Ward, William E.; Gault, William A.; Shepherd, Gordon G.; Hersom, Charles H.; Tai, C. C.; Solheim, Brian H.

1994-09-01

44

Narrow-band imaging optical chromocolonoscopy: Advantages and limitations  

PubMed Central

Narrow-band imaging (NBI) is an innovative optical technology that modifies the center wavelength and bandwidth of an endoscope’s light into narrow-band illumination of 415 ± 30 nm. NBI markedly improves capillary pattern contrast and is an in vivo method for visualizing microvessel morphological changes in superficial neoplastic lesions. The scientific basis for NBI is that short wavelength light falls within the hemoglobin absorption band, thereby facilitating clearer visualization of vascular structures. Several studies have reported advantages and limitations of NBI colonoscopy in the colorectum. One difficulty in evaluating results, however, has been non-standardization of NBI systems (Sequential and non-sequential). Utilization of NBI technology has been increasing worldwide, but accurate pit pattern analysis and sufficient skill in magnifying colonoscopy are basic fundamentals required for proficiency in NBI diagnosis of colorectal lesions. Modern optical technology without proper image interpretation wastes resources, confuses untrained endoscopists and delays inter-institutional validation studies. Training in the principles of “optical image-enhanced endoscopy” is needed to close the gap between technological advancements and their clinical usefulness. Currently available evidence indicates that NBI constitutes an effective and reliable alternative to chromocolonoscopy for in vivo visualization of vascular structures, but further study assessing reproducibility and effectiveness in the colorectum is ongoing at various medical centers.

Emura, Fabian; Saito, Yutaka; Ikematsu, Hiroaki

2008-01-01

45

Narrow-band optical transmission of metallic nanoslit arrays  

SciTech Connect

Metallic nanoslit arrays usually demonstrate wide transmission bands for transverse-magnetic-polarized incidence light. Here, we show that by introducing multi-dielectric layers underneath the metallic structure layer on the substrate, a narrow peak is formed, whose bandwidth can be down to a few nanometers. Three types of resonance modes in the region under the metal layer are identified responsible for the formation of the peak, i.e., a two-dimensional cavity resonance mode, which supports optical transmission, and two in-plane hybrid surface plasmon resonance modes locating on both sides of the peak that suppresses the transmission. Such structures can be applied in advanced photonic devices.

Sun Zhijun; Yang Ying; Zuo Xiaoliu [Department of Physics, Xiamen University, Xiamen 361005 (China)

2012-10-22

46

Narrow-band tunable alexandrite laser with passive Q switching  

SciTech Connect

An alexandrite laser with a self-injection of narrow-band radiation into its cavity was developed. A Fabry - Perot interferometer and a diffraction grating were used as dispersive components in an additional cavity. The cavity was switched by an LiF crystal with F{sub 3}{sup -} colour centres. The laser generated a single pulse of {approx} 180 ns duration and of 1.5 mJ energy, and with a spectrum 5 x 10{sup -3} cm{sup -1} wide. The laser emitted in the spectral range 720 - 780 nm. (lasers, active media)

Tyryshkin, I S [Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation); Ivanov, N A; Khulugurov, V M [Scientific-Research Institute of Applied Physics, Irkutsk State University, Irkutsk (Russian Federation)

1998-06-30

47

Slow electromagnetic pulse propagation through a narrow transmission band in a coaxial photonic crystal  

Microsoft Academic Search

We demonstrate the slow group-velocity propagation of electromagnetic pulses through a narrow transmission band of a simple coaxial photonic crystal. The narrow transmission band was formed by creating a defect in a periodic coaxial cable filter which resulted in a narrow-frequency passband within an otherwise forbidden band stop region. Strong normal dispersion within this region causes the group velocity of

J. N. Munday; W. M. Robertson

2003-01-01

48

Narrow band imaging of tumors using gold nanoshells  

NASA Astrophysics Data System (ADS)

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 tumor specific 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.

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

2009-02-01

49

Design of Interstage Coupling Apertures for Narrow-Band Tunable Coaxial BandPass Filters (Correspondence)  

Microsoft Academic Search

The design technique to be described in this note is applicable to tunable coaxial baud-pass filters having narrow bandwidths (i.e., less than 10 percent). In the frequeucy range of 1500 Mc to about 10,000 Mc, coaxial band-pass filters usually employ coupled ?\\/4 resonant cavities. Unlike direct coupled waveguide band-pass filters which are often amenable to a complete paper design, these

R. M. Kurzrok

1962-01-01

50

Narrow-band photometry and differential effects in close binary systems  

NASA Astrophysics Data System (ADS)

The application of narrow-band photometry to close binary systems is considered, with particular attention to the effects of eclipses. Models are examined, in which two normal absorption spectra are superposed and in which a third emission component is present. The purpose of these models is to relate to narrow-band observations of a kind similar to some preliminary results presented for U Sge in H-beta. It is shown that, under the conditions obtaining for such observations, the role of Doppler effects should be small, but that the observations should be sensitive to any difference between the limb darkening in the line and surrounding continuum. In the three-component models, the emitting volume is pictured as (1) a chromospheric shell and (2) an equational disk about the primary star. The expected modifications corresponding to such models of observations of primary eclipse are calculated. The possible applicability of the models to the preliminary observations is briefly considered.

Budding, E.; Marngus, N.

1980-02-01

51

Surgical treatment of laryngeal papillomatosis using narrow band imaging.  

PubMed

Laryngeal papillomatosis has a high rate of recurrence after surgery. Narrow band imaging (NBI) is a novel optical enhancement technology used for the diagnosis. This is the first report to date to indicate the availability of the combination of laryngomicro surgery and videoendoscopic surgery for laryngeal papillomatosis using NBI technology. The patients were a 34-year-old man and a 30-year-old man. Both patients underwent surgery in another hospital. However, due to recurrence, they were subsequently referred to the authors' department for further evaluation. The presence of papillomas was confirmed by NBI, and the papillomas were removed using an XPS Micro Debrider and a CO2 laser. Using the NBI system, the border between the normal mucosa and the papillomas could be clearly identified, allowing precise resection. Further treatment on the lesions has been carried out several times to date using NBI. The lesions have now been eradicated without further recurrence. PMID:22597574

Imaizumi, Mitsuyoshi; Okano, Wataru; Tada, Yasuhiro; Omori, Koichi

2012-05-17

52

Precisely tunable, narrow-band pulsed dye laser  

SciTech Connect

A narrow-band, precisely tunable dye laser pumped by an injection-seeded YAG laser is described. The laser achieves an output of 100 mJ/pulse and 40{percent} efficiency when one uses Rhodamine 6G dyes. The output pulse is Gaussian both in time and spatial profile. The laser oscillator employs an intracavity {acute e}talon that is repetitively pressure scanned over one free spectral range while the grating successively steps to consecutive {acute e}talon modes. We pressure scanned the {acute e}talon under computer control using a bellows. Methods are described for calibrating the tuning elements for absolute precision. We demonstrated that the laser has an absolute precision of {plus_minus}0.4 pm over a 1.0-nm scan. This accuracy is achievable over the wavelength range of a dye. {copyright} {ital 1996 Optical Society of America.}

Bhatia, P.S.; Keto, J.W. [Department of Physics, University of Texas at Austin, Austin, Texas 78712-1081 (United States)

1996-07-01

53

Narrow-K-band Observations of the GJ 1214 System  

NASA Astrophysics Data System (ADS)

GJ 1214 is a nearby M dwarf star that hosts a transiting super-Earth-size planet, making this system an excellent target for atmospheric studies. Most studies find that the transmission spectrum of GJ 1214b is flat, which favors either a high mean molecular weight or cloudy/hazy hydrogen (H) rich atmosphere model. Photometry at short wavelengths (<0.7 ?m) and in the K band can discriminate the most between these different atmosphere models for GJ 1214b, but current observations do not have sufficiently high precision. We present photometry of seven transits of GJ 1214b through a narrow K-band (2.141 ?m) filter with the Wide Field Camera on the 3.8 m United Kingdom Infrared Telescope. Our photometric precision is typically 1.7 × 10-3 (for a single transit), comparable with other ground-based observations of GJ 1214b. We measure a planet-star radius ratio of 0.1158 ± 0.0013, which, along with other studies, also supports a flat transmission spectrum for GJ 1214b. Since this does not exclude a scenario where GJ 1214b has an H-rich envelope with heavy elements that are sequestered below a cloud/haze layer, we compare K-band observations with models of H2 collision-induced absorption in an atmosphere for a range of temperatures. While we find no evidence for deviation from a flat spectrum (slope s = 0.0016 ± 0.0038), an H2-dominated upper atmosphere (<60 mbar) cannot be excluded. More precise observations at <0.7 ?m and in the K band, as well as a uniform analysis of all published data, would be useful for establishing more robust limits on atmosphere models for GJ 1214b.

Colón, Knicole D.; Gaidos, Eric

2013-10-01

54

Design of narrow band notch filter based on guided mode resonance effect in thin film layers  

NASA Astrophysics Data System (ADS)

Narrow band notch filters based on grating waveguide structure have been studied using rigorous coupled wave approximations (RCWA). It has been shown that ultra-narrow bandwidth (0.0042 nm) can be achieved with sinusoidal grating profile.

Debnath, Amrita; Kumar, Sanjiva; Udupa, D. V.; Sahoo, N. K.

2012-06-01

55

Narrow-band band-pass filters on silicon substrates at 30 GHz  

Microsoft Academic Search

Using optimized ion implantation, we have fabricated high performance 2-pole and 3-pole CPW filters on Si substrates at ?30 GHz, with very narrow 1.0 (3.1%) GHz and 0.75 (2.5%) GHz pass-band as well as small insertion loss. Microstrip filters on Si show small 3.2 dB loss at 27 GHz, which has smaller size than CPW case without the large coplanar

D. S. Yu; C. F. Cheng; K. T. Chan; A. Chin; S. P. McAlister; C. Zhu; M. F. Li; D. L. Kwong

2004-01-01

56

Design of Wide-Band (and Narrow-Band) BandPass Microwave Filters on the Insertion Loss Basis  

Microsoft Academic Search

A method for design of band-pass microwave filters is described that combines the image and insertion-loss points of view to give an approximate design method having simplicity, but also high precision. This method is applicable for filter designs ranging from narrow to very wide bandwidths (2 to 1 or more). The desired insertion loss characteristic is obtained by use of

G. L. Matthaei

1960-01-01

57

Spectrally narrowed edge emission from leaky waveguide modes in organic light-emitting diodes  

SciTech Connect

A dramatic spectral line narrowing of the edge emission at room temperature from tris(quinolinolate) Al (Alq{sub 3}), N,N{prime}-diphenyl-N,N{prime}-bis(1-naphthylphenyl)-1,1{prime}-biphenyl-4,4{prime}-diamine (NPD), 4,4{prime}-bis(2,2{prime}-diphenyl-vinyl)-,1{prime}-biphenyl (DPVBi), and some guest-host small molecular organic light-emitting diodes (OLEDs), fabricated on indium tin oxide (ITO)-coated glass, is described. In all but the DPVBi OLEDs, the narrowed emission band emerges above a threshold thickness of the emitting layer, and narrows down to a full width at half maximum of only 5-10 nm. The results demonstrate that this narrowed emission is due to irregular waveguide modes that leak from the ITO to the glass substrate at a grazing angle. While measurements of variable stripe length l devices exhibit an apparent weak optical gain 0 {le} g {le} 1.86 cm{sup -1}, there is no observable threshold current or bias associated with this spectral narrowing. In addition, in the phosphorescent guest-host OLEDs, there is no decrease in the emission decay time of the narrowed edge emission relative to the broad surface emission. It is suspected that the apparent weak optical gain is due to misalignment of the axis of the waveguided mode and the axis of the collection lens of the probe.

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

2009-11-03

58

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

Microsoft Academic Search

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

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

2001-01-01

59

Role of narrow band imaging in endoscopic submucosal dissection  

PubMed Central

Narrow band imaging (NBI) is a new image enhancement system employing optic digital methods to enhance images of blood vessels on mucosal surfaces, allowing improved visualization of mucosal surface structures. Studies have progressed over the last several years, and the clinical usefulness has been demonstrated. NBI has become frequently applied for preoperative diagnosis before endoscopic submucosal dissection (ESD) of digestive tract cancers, as well as for assessment of the range of ESD for en-bloc resection of large lesions. Consensus has been reached with regard to the usefulness of NBI for detecting micro-lesions of esophageal squamous cell carcinoma indicated for ESD, for the diagnosis of the range and depth. NBI has also been attracting attention for diagnosing gastric cancer based on the observation of micro blood vessels on the mucosal surface and mucosal surface microstructures. The usefulness of NBI has been reported in relation to various aspects of colon cancer, including diagnoses of the presence, quality, range, and depth of lesions. However, as NBI has not surpassed diagnostic methods based on magnifying observation combined with the established and widely employed dye method, its role in ESD is limited at present. Although NBI is very useful for the diagnosis of digestive tract cancers, comprehensive endoscopic diagnosis employing the combination of conventional endoscopy including dye spraying, EUS, and NBI may be important and essential for ESD.

Nonaka, Kouichi; Nishimura, Makoto; Kita, Hiroto

2012-01-01

60

Role of narrow band imaging in endoscopic submucosal dissection.  

PubMed

Narrow band imaging (NBI) is a new image enhancement system employing optic digital methods to enhance images of blood vessels on mucosal surfaces, allowing improved visualization of mucosal surface structures. Studies have progressed over the last several years, and the clinical usefulness has been demonstrated. NBI has become frequently applied for preoperative diagnosis before endoscopic submucosal dissection (ESD) of digestive tract cancers, as well as for assessment of the range of ESD for en-bloc resection of large lesions. Consensus has been reached with regard to the usefulness of NBI for detecting micro-lesions of esophageal squamous cell carcinoma indicated for ESD, for the diagnosis of the range and depth. NBI has also been attracting attention for diagnosing gastric cancer based on the observation of micro blood vessels on the mucosal surface and mucosal surface microstructures. The usefulness of NBI has been reported in relation to various aspects of colon cancer, including diagnoses of the presence, quality, range, and depth of lesions. However, as NBI has not surpassed diagnostic methods based on magnifying observation combined with the established and widely employed dye method, its role in ESD is limited at present. Although NBI is very useful for the diagnosis of digestive tract cancers, comprehensive endoscopic diagnosis employing the combination of conventional endoscopy including dye spraying, EUS, and NBI may be important and essential for ESD. PMID:23125896

Nonaka, Kouichi; Nishimura, Makoto; Kita, Hiroto

2012-09-16

61

Engineering integrated pure narrow-band photon sources  

NASA Astrophysics Data System (ADS)

Engineering and controlling well-defined states of light for quantum information applications is of increasing importance as the complexity of quantum systems grows. For example, in quantum networks, high multi-photon interference visibility requires properly devised pure photon sources. In this paper, we present a theoretical model for a spontaneous parametric down conversion source based on an integrated cavity-waveguide, where single narrow-band, possibly distinct, resonant modes for the idler and the signal fields can be generated. This mode selection takes advantage of the clustering effect, due to the intrinsic dispersion of the nonlinear material. We show that, by engineering the clustering effect in an integrated cavity-waveguide and by using a standard detector, one can efficiently generate heralded pure single photons even with a continuous-wave pumping mode. The photon source proposed in this paper is extremely flexible and could easily be adapted to a wide variety of wavelengths and applications, such as long-distance quantum communication.

Pomarico, E.; Sanguinetti, B.; Osorio, C. I.; Herrmann, H.; Thew, R. T.

2012-03-01

62

Single-narrow-band red upconversion fluorescence of ZnO nanocrystals codoped with Er and Yb and its achieving mechanism  

NASA Astrophysics Data System (ADS)

ZnO nanocrystals doped with Er3+ and Yb3+ ions were synthesized by the chemical-combustion process. The single-narrow-band red fluorescence (centered at 662 nm) in ZnO:Er, Yb was observed under 115 mW excitation of a 980 nm laser diode. The full width at half maximum of the red emission band is equal to 30 nm, which is the narrowest emission band ever reported in Er3+ doped systems. This narrower emission band in ZnO:Er, Yb nanocrystal is beneficial for improving the precision and sensitivity of the indicators in fluorescent label detection. The mechanisms resulting in the single-narrow emission band were analyzed by combining X-ray diffraction, Raman spectra, fluorescence spectra, and a simple model.

Liu, Yunxin; Yang, Qibin; Xu, Changfu

2008-09-01

63

Optical spectra of narrow emission line Palomar-Green galaxies  

Microsoft Academic Search

Spectra were obtained of 35 of the 36 narrow emission line galaxies isolated in the Palomar-Green (PG) survey of Green, Schmidt, and Liebert (1986). Of these, three are narrow-line Seyfert 1 galaxies, three more are Seyfert 1.5 galaxies, and only one, PG 2259 + 157 = NGC 7465 = Mrk 313, is a relatively low-ionization active galactic nucleus, a marginal

Donald E. Osterbrock; Richard W. Pogge

1987-01-01

64

Surface band-gap narrowing in quantized electron accumulation layers.  

PubMed

An energy gap between the valence and the conduction band is the defining property of a semiconductor, and the gap size plays a crucial role in the design of semiconductor devices. We show that the presence of a two-dimensional electron gas near to the surface of a semiconductor can significantly alter the size of its band gap through many-body effects caused by its high electron density, resulting in a surface band gap that is much smaller than that in the bulk. Apart from reconciling a number of disparate previous experimental findings, the results suggest an entirely new route to spatially inhomogeneous band-gap engineering. PMID:20867408

King, P D C; Veal, T D; McConville, C F; Zúñiga-Pérez, J; Muñoz-Sanjosé, V; Hopkinson, M; Rienks, E D L; Jensen, M Fuglsang; Hofmann, Ph

2010-06-24

65

Narrow band and wide angle hemispherical interference optical filter  

NASA Astrophysics Data System (ADS)

An optical interference filter has narrow linewidth and wide acceptance angle and includes a hemisphere coated to provide a narrow bandpass filter at a desired wavelength at normal incidence while other wavelengths at normal incidence are absorbed or reflected. A photodetector placed at the center of the hemisphere detects the desired wavelength only. Other wavelengths that are shorter than the wavelength of the filter are transmitted through the filter to be absorbed by a black absorbing surface around the photodetector. Thus, only the frequency of interest at normal incidence provides a representative signal at the detector.

Rieger, Harry

1989-07-01

66

Narrow X-band tunable MMIC filters employing active resonators as local feedback  

Microsoft Academic Search

Monolithic microwave active inductors have been used to realize very narrow X-band tunable filters. The active inductors were used in local feedback configurations. This results in simple structures that make optimal use of the unloaded resonator quality factor. MMIC band pass and band stop filters were designed, realized and fully characterized

F. E. Van Vliet; J. L. Tauritz; F. L. M. Van Den Bognaart; R. G. F. Baets

1997-01-01

67

Optical Observations of M81 Galaxy Group in Narrow Band [SII] and H_alpha Filters: Holmberg IX  

NASA Astrophysics Data System (ADS)

We present observations of the nearby tidal dwarf galaxy Holmberg IX in M81 galaxy group in narrow band [SII] and H? filters, carried out in March and November 2008 with the 2m RCC telescope at NAO Rozhen, Bulgaria. {Our search for resident supernova remnants (identified as sources with enhanced [SII] emission relative to their H? emission) in this galaxy yielded no sources of this kind, besides M&H 10-11 or HoIX X-1.} Nevertheless, we found a number of objects with significant H? emission that probably represent uncatalogued HII regions.

Arbutina, B.; Ilic, D.; Stavrev, K.; Urosevic, D.; Vukotic, B.; Onic, D.

2009-12-01

68

Laser-produced lithium plasma as a narrow-band extended ultraviolet radiation source for photoelectron spectroscopy.  

PubMed

Extended ultraviolet (EUV) emission characteristics of a laser-produced lithium plasma are determined with regard to the requirements of x-ray photoelectron spectroscopy. The main features of interest are spectral distribution, photon flux, bandwidth, source size, and emission duration. Laser-produced lithium plasmas are characterized as emitters of intense narrow-band EUV radiation. It can be estimated that the lithium Lyman-alpha line emission in combination with an ellipsoidal silicon/molybdenum multilayer mirror is a suitable EUV source for an x-ray photoelectron spectroscopy microscope with a 50-meV energy resolution and a 10-mum lateral resolution. PMID:18268711

Schriever, G; Mager, S; Naweed, A; Engel, A; Bergmann, K; Lebert, R

1998-03-01

69

A Near-Infrared Narrow-band Imaging Survey to Search for Massive Stars in Cl 1806-20  

Microsoft Academic Search

We survey the environment surrounding Cl 1806-20 using near-infrared narrow-band imaging to search for Brgamma features indicative of massive stars. Using this technique, we successfully detect previously identified massive stars in the cluster. While we detect no new emission line stars, establishing a firm upper limit on the number of Wolf Rayets and Luminous Blue Variables, we do find several

Michelle L. Edwards; Reba M. Bandyopadhyay; Stephen S. Eikenberry; Valerie J. Mikles; Dae-Sik Moon

2011-01-01

70

A Near-Infrared Narrow-band Imaging Survey for Massive Stars in Cl 1806-20  

Microsoft Academic Search

We survey the environment of the Soft Gamma-Ray Repeater SGR 1806-20 using near-infrared narrow-band imaging to search for Br gamma features indicative of massive stars. Using this technique, we successfully detect previously identified massive stars in Cl 1806-20, the established natal star cluster of SGR 1806-20. We detect no new emission line stars, establishing a firm upper limit on the

Michelle L. Edwards; R. M. Bandyopadhyay; S. S. Eikenberry; D. Moon; V. J. Mikles

2010-01-01

71

Accuracy of various theories of band-gap narrowing in p -doped semiconductors  

Microsoft Academic Search

We analyze band-gap narrowing in p-doped zinc-blende-structure semiconductors with the aid of a newly developed analytic expression for the valence-band dielectric function. We also investigate the accuracy of band-gap calculations involving the plasmon-pole and damped-plasmon-pole dielectric functions as well as of expressions for the band-gap shift based on theories of plasma exchange and correlation energies. In the particular case of

W. Bardyszewski; D. Yevick

1987-01-01

72

Novel sources and detectors for coherent tunable narrow-band terahertz radiation in free space  

Microsoft Academic Search

A novel scheme for the optical generation and coherent detection of tunable narrow-band far-infrared radiation in free space is described. This technique involves the optical heterodyning of two linearly chirped broadband pulses to produce a quasi-sinusoidal intensity modulation at tunable terahertz frequencies. The frequency content of the narrow-band terahertz radiation produced by mixing chirped optical pulses in a nonlinear op-

Aniruddha S. Weling; David H. Auston

1996-01-01

73

Oxygen vacancy induced band gap narrowing of ZnO nanostructures by an electrochemically active biofilm  

NASA Astrophysics Data System (ADS)

Band gap narrowing is important and advantageous for potential visible light photocatalytic applications involving metal oxide nanostructures. This paper reports a simple biogenic approach for the promotion of oxygen vacancies in pure zinc oxide (p-ZnO) nanostructures using an electrochemically active biofilm (EAB), which is different from traditional techniques for narrowing the band gap of nanomaterials. The novel protocol improved the visible photocatalytic activity of modified ZnO (m-ZnO) nanostructures through the promotion of oxygen vacancies, which resulted in band gap narrowing of the ZnO nanostructure (Eg = 3.05 eV) without dopants. X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and high resolution transmission electron microscopy confirmed the oxygen vacancy and band gap narrowing of m-ZnO. m-ZnO enhanced the visible light catalytic activity for the degradation of different classes of dyes and 4-nitrophenol compared to p-ZnO, which confirmed the band gap narrowing because of oxygen defects. This study shed light on the modification of metal oxide nanostructures by EAB with a controlled band structure.Band gap narrowing is important and advantageous for potential visible light photocatalytic applications involving metal oxide nanostructures. This paper reports a simple biogenic approach for the promotion of oxygen vacancies in pure zinc oxide (p-ZnO) nanostructures using an electrochemically active biofilm (EAB), which is different from traditional techniques for narrowing the band gap of nanomaterials. The novel protocol improved the visible photocatalytic activity of modified ZnO (m-ZnO) nanostructures through the promotion of oxygen vacancies, which resulted in band gap narrowing of the ZnO nanostructure (Eg = 3.05 eV) without dopants. X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and high resolution transmission electron microscopy confirmed the oxygen vacancy and band gap narrowing of m-ZnO. m-ZnO enhanced the visible light catalytic activity for the degradation of different classes of dyes and 4-nitrophenol compared to p-ZnO, which confirmed the band gap narrowing because of oxygen defects. This study shed light on the modification of metal oxide nanostructures by EAB with a controlled band structure. Electronic supplementary information (ESI) available: Pretreatment of EAB and its SEM images, schematic representation of the modification process and absorbance spectra. See DOI: 10.1039/c3nr02678g

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

2013-09-01

74

Assignment of Red Rectangle Visible Emission Bands  

Microsoft Academic Search

An explanation based upon nonlinear photoexcitation of H2 is offered for the most striking features seen in the visible emission spectrum of the Red Rectangle (RR) nebula - three intense, relatively sharp, red-shaded bands appearing near 5798 Angstroms, 5851 Angstroms, and 6615 Angstroms. In the model, the lambda 5851 band is assigned as an emission step in a Ly-alpha -pumped,

P. P. Sorokin; J. H. Glownia

2000-01-01

75

Characterization of microwave magnetic narrow band filters by ferromagnetic resonance  

NASA Astrophysics Data System (ADS)

Ferromagnetic resonance cavity and microstrip excitation experiments have been performed on a straight edge yttrium iron garnet resonator. Both excitation systems have been modeled as band-stop configurations and a mapping from the swept bias magnetic field domain to the frequency domain has been elaborated to compare them in terms of the dispersion and the amplitude of the magnetostatic wave modes.

Bousbahi, Khaled; Marcelli, Romolo

2000-05-01

76

Anomalous resistivity and superconductivity in the two-band Hubbard model with one narrow band (Review)  

NASA Astrophysics Data System (ADS)

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 effects and other mechanisms for mass-enhancement (related to the 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 a tendency towards phase separation (towards negative partial compressibility of heavy particles) in the 3D case with a large mismatch between the densities of heavy and light bands in the strong coupling limit. We also find that for low temperatures and equal densities, the resistivity in a homogeneous state R(T)~T2 behaves as a Fermi-liquid in both 3D and 2D. For temperatures greater than the effective bandwidth for heavy electrons T>Wh*, the coherence of the heavy component breaks down completely. The heavy particles move diffusively in the surrounding light particles. At the same time, light particles scatter on heavy particles as if on immobile (static) impurities. Under these conditions, the heavy component is marginal, while the light component is not. The resistivity approaches saturation for T>Wh* in the 3D case. In 2D the resistivity has a maximum and a localization tail owing to weak-localization corrections of the Altshuler-Aronov type. This behavior of resistivity in 3D could be relevant for some uranium-based heavy-fermion compounds such as UNi2Al3 and in 2D, for some other mixed-valence compounds, possibly including layered manganites. We also consider briefly the superconductive (SC) instability in this model. The leading instability tends to p-wave pairing and is governed by an enhanced Kohn-Luttinger mechanism for SC at low electron densities. The critical temperature corresponds to the pairing of heavy electrons via polarization of the light electrons in 2D.

Kagan, M. Yu.; Valkov, V. V.

2011-01-01

77

Superconducting narrow band pass filters for advanced multiplexers  

Microsoft Academic Search

X-band microstrip filters with a 50-MHz-wide passband that provide 1.3-dB insertion loss at 77 K using copper ground planes have been built. Recent advances in double side coating of lanthanum aluminate substrates with YBa2Cu3O7- delta will lower this figure to 0.6 dB. Circuit designs were evaluated for intermodulation distortion effects. An improvement over previous designs has increased the third-order output

A. Fathy; D. Kalokitis; V. Pendrick; E. Balohoubek; A. Pique; M. Mathur

1993-01-01

78

Oxygen vacancy induced band gap narrowing of ZnO nanostructures by an electrochemically active biofilm.  

PubMed

Band gap narrowing is important and advantageous for potential visible light photocatalytic applications involving metal oxide nanostructures. This paper reports a simple biogenic approach for the promotion of oxygen vacancies in pure zinc oxide (p-ZnO) nanostructures using an electrochemically active biofilm (EAB), which is different from traditional techniques for narrowing the band gap of nanomaterials. The novel protocol improved the visible photocatalytic activity of modified ZnO (m-ZnO) nanostructures through the promotion of oxygen vacancies, which resulted in band gap narrowing of the ZnO nanostructure (Eg = 3.05 eV) without dopants. X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and high resolution transmission electron microscopy confirmed the oxygen vacancy and band gap narrowing of m-ZnO. m-ZnO enhanced the visible light catalytic activity for the degradation of different classes of dyes and 4-nitrophenol compared to p-ZnO, which confirmed the band gap narrowing because of oxygen defects. This study shed light on the modification of metal oxide nanostructures by EAB with a controlled band structure. PMID:23938937

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

2013-08-13

79

A prospective randomised study on narrow-band imaging versus conventional colonoscopy for adenoma detection: does narrow-band imaging induce a learning effect?  

Microsoft Academic Search

Background and aims:Colonoscopy is an established method of colorectal cancer screening, but has an adenoma miss rate of 10–20%. Detection rates are expected to improve with optimised visualisation methods. This prospective randomised study evaluated narrow-band imaging (NBI), a new technique that may enhance image contrast in colon adenoma detection.Methods:Eligible patients presenting for diagnostic colonoscopy were randomly assigned to undergo wide-angle

A Adler; H Pohl; I S Papanikolaou; H Abou-Rebyeh; G Schachschal; W Veltzke-Schlieker; A C Khalifa; E Setka; M Koch; B Wiedenmann; T Rösch

2008-01-01

80

Generation of narrow-band terahertz coherent Cherenkov radiation in a dielectric wakefield structure  

NASA Astrophysics Data System (ADS)

This study explores the use of a dielectric-lined waveguide structure as a means of producing narrow-band terahertz radiation in the form of electron-beam-driven coherent Cherenkov radiation wakefields. This concept builds on previously studied scenarios such as the Cherenkov maser and the Cherenkov free-electron laser. It is distinct in that it relies solely on coherent wakefield excitation instead of a microbunching instability gain process, in analogy to the superradiant regime of FEL operation. The narrow bandwidth is due to the single-mode nature of the excitation, enabled by the exclusion (due to coherence) of discrete waveguide modes with wavelengths shorter than the driving electron bunch length. This allows an inherently broadband beam current profile to radiate power into a single frequency, which is selectable by appropriate choice of design parameters. The theoretical component of this dissertation is aimed at making predictions for comparison with experimental results. The functional form and propagating mode frequencies of the electromagnetic fields in the waveguide structure are found by eigenmode solution in the source-free case beginning from Maxwell's equations; the response of the structure to a driving electron bunch is then found using a wakefield formalism. Predictions for the frequencies and radiated energy levels obtained from this analysis are corroborated computationally using the commercial particle-in-cell simulation code OOPIC PRO. The experiment is designed to be a proof-of-principle demonstration of the effectiveness of this scenario in converting the energy in an electron beam into electromagnetic radiation. We present detailed measurements showing a narrow emission spectrum peaked at 367 +/- 3 GHz from a 1 cm long fused silica capillary tube with sub-mm transverse dimensions, matching the predicted (analytical and computational) TM01 mode resonance to within 1% error. This measurement confirms the expected preferential coherent excitation of the TM01 mode over the HEM11 mode, which lies nearby in frequency but still decisively outside the error estimate established over multiple measurements. The measured 3 dB bandwidth is on the order of ? 10% and is seen to be transform-limited. We observe a 100 GHz shift in the emitted central frequency when the tube wall thickness is changed by 50 mum, demonstrating the modular tunability of the source. Calibrated measurements of the radiated energy register up to 10 muJ per 60-80 ps pulse for an incident sub-picosecond electron beam carrying 200 pC of charge, corresponding to a peak power of approximately 150 kW. A case study considering the implementation of this scenario using a 10-cm-long structure with smaller transverse dimensions indicates a possible yield of 50 MW peak power at 1.8 THz and 0.1% bandwidth. This dissertation reports the first direct measurements of narrow-band THz coherent Cherenkov radiation driven by a sub-picosecond electron beam in a dielectric wakefield structure, representing a successful adaptation of the previously proven Cherenkov FEL concept to the realm of ultra-short electron beams such as are available in state-of-the-art user facilities around the world. These results prove the potential of this method to produce tunable, narrow-band, pulse-length-variable, multi-megawatt peak-power radiation at f > 1 THz in existing modern electron accelerators.

Cook, Alan Matthew

81

Manipulating stimulated coherent anti-Stokes Raman spectroscopy signals by broad-band and narrow-band pulses  

PubMed Central

A transition-amplitude based representation of heterodyne detected coherent anti-Stokes Raman signals is used to separate them into a parametric component that involves no change in the material and dissipative processes associated with various transitions between states. Qualitatively different contributions from the two processes are predicted for the signal generated by an overlapping narrow (picosecond) and broad-band (femtosecond) pulse.

Rahav, Saar; Roslyak, Oleksiy; Mukamel, Shaul

2009-01-01

82

Optical narrow-band filters using optical amplification with distributed feedback  

Microsoft Academic Search

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

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

1988-01-01

83

Tunable narrow-band terahertz generation from periodically poled lithium niobate  

SciTech Connect

We describe a technique for generating tunable narrow-band terahertz radiation via optical rectification in periodically-poled lithium niobate. Frequency tuning is accomplished by spatially chirping the domain width laterally to the beam propagation direction, and adjusting the temperature of the sample. We demonstrate tuning over a continuous range from 0.8 to 2.5 THz. The bandwidth of the terahertz waveforms is as narrow as 0.02 THz. {copyright} 2001 American Institute of Physics.

Lee, Y. S.; Meade, T.; Norris, T. B.; Galvanauskas, A.

2001-06-04

84

Envelope amplitude analysis following narrow-band filtering: a technique for ultrasonic tissue characterization.  

PubMed

Ultrasonic waveforms backscattered from tissue simulating phantoms and from normal and cirrhotic human livers in vivo were digitized to a standard dynamic range prior to envelope detection and determination of envelope amplitude distributions. For 11 individual narrow-band Gaussian-shaped filters of -6 dB bandwidth 200 kHz, and of center frequencies from 2 to 4 MHz, envelope amplitude distributions were plotted and mean values of the values distributions computed. Analysis of data was performed for data from a phantom containing only relatively small graphite scatters (less than 170 mu), and a similar phantom to which glass spheres 0.5 mm in diameter had been added homogeneously. For lower center frequency narrow-band filters, significantly more high-amplitude occurrences were observed for data from the phantom to which glass spheres had been added. Higher center frequency narrow-band filters gave significantly more high-amplitude occurrences for the phantom containing only small scatters. Similar data analysis was performed for in vivo human liver data from ten normal subjects and five patients with known cirrhosis of the liver. For the cirrhotic and normal livers, data analysis using narrow-band filters of relatively low center frequency resulted in more high- amplitude occurrences for cirrhotic, compared to normal liver; the converse was true for narrow-band filtration at relatively high center frequencies. Determination of mean amplitude following narrow-band filtration with a filter centered at 3.4 MHz was found to be quite repeatable for the normal and cirrhotic liver data; analysis of variance showed the measurement was 94.1% a function of the subject examined, and 5.9% related to the data acquisition session.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3306304

Sommer, F G; Stern, R A; Howes, P J; Young, H

85

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

PubMed

We demonstrate the first proof of principle differential phase shift (DPS) quantum key distribution (QKD) using narrow-band heralded single photons with amplitude-phase modulations. In the 3-pulse case, we obtain a quantum bit error rate (QBER) as low as 3.06% which meets the unconditional security requirement. As we increase the pulse number up to 15, the key creation efficiency approaches 93.4%, but with a cost of increasing the QBER. Our result suggests that narrow-band single photons maybe a promising source for the DPS-QKD protocol. PMID:23609661

Liu, Chang; Zhang, Shanchao; Zhao, Luwei; Chen, Peng; Fung, C-H F; Chau, H F; Loy, M M T; Du, Shengwang

2013-04-22

86

Empirical determination of the energy band gap narrowing in highly doped n+ silicon  

NASA Astrophysics Data System (ADS)

Highly doped regions in silicon devices should be analyzed using Fermi-Dirac statistics, taking into account energy band gap narrowing (BGN). An empirical expression for the BGN as a function of dopant concentration is derived here by matching the modeled and measured thermal recombination current densities J0 of a broad range of n+ dopant concentration profiles prepared by phosphorus diffusion. The analysis is repeated with Boltzmann statistics in order to determine a second empirical expression for the apparent energy band gap narrowing, which is found to be in good agreement with previous work.

Yan, Di; Cuevas, Andres

2013-07-01

87

Starburst activity in a ROSAT narrow emission-line galaxy  

NASA Astrophysics Data System (ADS)

We present multiwaveband photometric and optical spectropolarimetric observations of the R=15.9 narrow emission-line galaxy R117_A which lies on the edge of the error circle of the ROSAT X-ray source R117. The overall spectral energy distribution of the galaxy is well modelled by a combination of a normal spiral galaxy and a moderate-strength burst of star formation. The far-infrared and radio emission is extended along the major axis of the galaxy, indicating an extended starburst. On positional grounds, the galaxy is a good candidate for the identification of R117, and the observed X-ray flux is very close to what would be expected from a starburst of the observed far-infrared and radio fluxes. Although an obscured high-redshift QSO cannot be entirely ruled out as contributing some fraction of the X-ray flux, we find no candidates to K=20.8 within the X-ray error box, and so conclude that R117_A is responsible for a large fraction, if not all, of the X-ray emission from R117. Searches for indicators of an obscured AGN in R117_A have so far proven negative; deep spectropolarimetric observations show no signs of broad lines to a limit of 1per cent and, for the observed far-infrared and radio emission, we would expect 10 times greater X-ray flux if the overall emission were powered by an AGN. We therefore conclude that the X-ray emission from R117 is dominated by starburst emission from the galaxy R117_A.

Gunn, Katherine F.; McHardy, I. M.; Almaini, O.; Shanks, T.; Sumner, T. J.; Muxlow, T. W. B.; Efstathiou, A.; Jones, L. R.; Croom, S. M.; Manners, J. C.; Newsam, A. M.; Mason, K. O.; Serjeant, S. B. G.; Rowan-Robinson, M.

2001-06-01

88

Narrow saturated absorption resonances in the transmission band of an active interferometer  

Microsoft Academic Search

The shape of the transmission band of an active interferometer, a resonator with amplification and absorption cells excited\\u000a by an external signal, is studied. Upon tuning the external signal frequency, the narrow saturated absorption resonances can\\u000a be observed in the transmission band of the interferometer. It is shown that, by varying the gain, the resonance absorption\\u000a amplitude can be compensated

S. N. Bagaev; A. A. Kurbatov; E. A. Titov

2000-01-01

89

Spatial structure analysis of direct-drive implosion cores at OMEGA using x-ray narrow-band core images  

SciTech Connect

The spectroscopic analysis of x-ray narrow-band images and space-integrated x-ray line spectra from argon-doped deuterium-filled inertial confinement fusion implosion experiments yields information about the spatial profiles in the compressed core. We discuss the analysis of direct-drive implosion experiments at OMEGA, in which images were obtained with a multimonochromatic imaging instrument. The analysis method considers data based on the argon He{beta} and Ly{beta} spectral features and their associated Li- and He-like satellites. The temperature gradient structure is investigated by using the sensitivity of the Ly{beta}/He{beta} emissivity ratio to the temperature.

Welser, L. A.; Mancini, R. C.; Nagayama, T.; Tommasini, R.; Koch, J. A.; Izumi, N.; Delettrez, J. A.; Marshall, F. J.; Regan, S. P.; Smalyuk, V. A.; Golovkin, I. E.; Haynes, D. A.; Kyrala, G. [Department of Physics, University of Nevada, Reno, M.S. 220, Reno, Nevada 89557 (United States); Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550-9234 (United States); Laboratory for Laser Energetics, University of Rochester, New York 14623 (United States); Prism Computational Sciences, Madison, Wisconsin 53711 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2006-10-15

90

Elliptical cavity resonators for dual-mode narrow-band filters  

Microsoft Academic Search

A novel cavity resonator with elliptical cross section is proposed in order to realize dual-mode narrow-band filters without tuning and coupling elements. The absence of any discontinuity inside the cavities significantly enhances the unloaded Q, the ability to operate with higher power levels, and the ease of manufacturing. Proper choice of the ellipticity and of the inclination angle controls the

Luciano Accatino; Giorgio Bertin; Mauro Mongiardo

1997-01-01

91

A new structure for narrow transition band, lowpass digital filter design  

Microsoft Academic Search

In this paper, a new class of lowpass linear phase FIR filters is introduced. It is shown that lowpass filters with narrow transition bands can be realized efficiently by a structured form composed mainly of a few small FIR filters. The modular structure is suited for an implementation by a fast short convolution algorithm or a few single-chip filter IC's.

Zhongqi Jing; Adly Fam

1984-01-01

92

Narrow-band hairpin-comb filters for HTS and other applications  

Microsoft Academic Search

The folded half-wavelength resonators in hairpin-comb filters all have the same orientation whereas the orientations of the resonators in conventional hairpin filters alternates. Hairpin-comb filters have attractive properties for design of compact, narrow-band filters such as are often desired for high-temperature-superconductivity and other applications

G. L. Matthaei; N. O. Fenzi; R. Forse; S. Rohlfing

1996-01-01

93

Narrow Band Imaging Applied to Pleuroscopy for the Assessment of Vascular Patterns of the Pleura  

Microsoft Academic Search

Background: Narrow band imaging (NBI), which enhances blood vessels, is a new endoscopic technology for diagnosing malignancies, but it has not been investigated for pleuroscopy. Objectives: To evaluate the efficacy of NBI applied to pleuroscopy for detecting malignant lesions by assessing vascular patterns of the pleura. Methods: From May 2006 to September 2008, 45 patients with undiagnosed pleural ef-fusion underwent

Atsuko Ishida; Fuzuki Ishikawa; Miho Nakamura; Yuka M. Miyazu; Masamichi Mineshita; Noriaki Kurimoto; Junki Koike; Takashi Nishisaka; Teruomi Miyazawa; Philippe Astoul

2009-01-01

94

Comparison of efficiency measurements for narrow band antennas using UWB Wheeler Cap and Reverberation Chamber  

Microsoft Academic Search

The topic of this paper is the narrow band antenna efficiency measurement. Two test beds are investigated and compared namely the Reverberation Chamber (RC) and the UWB Wheeler Cap (UWB WCap). The RC, first designed for EMC measurements, is able to measure almost any kinds of antennas with control uncertainty. The second one designed for very broadband systems, can also

Gwenn Le Fur; Christophe Lemoine; Philippe Besnier; Ala Sharaiha

2009-01-01

95

Design of a Pin-Diode, Narrow Band Spot Microwave Switch.  

National Technical Information Service (NTIS)

The computer aided design of a narrow band, pin-diode SPDT switch, for use in a 4.75 GHz Dicke radiometer, is described. Although the example switch is constructed on microstrip, the circuit analysis and computer program description are more generally app...

D. E. Meharry

1974-01-01

96

Shoreline Extraction from RADARSAT-2 Intensity Imagery Using a Narrow Band Level Set Segmentation Approach  

Microsoft Academic Search

This paper presents a semi-automated method for shoreline extraction from RADARSAT-2 intensity imagery. First, a preprocessing is applied to enhance the contrast of the SAR image. Second, thresholding combined with morphological filtering is employed to segment the SAR image into the land and the sea. Third, narrow band level set segmentation is implemented to refine the segmentation result. In the

Yuanming Shu; Jonathan Li; Gary Gomes

2010-01-01

97

Simulation of an Electrostatic Energy Harvester at Large Amplitude Narrow and Wide Band Vibrations  

Microsoft Academic Search

An electrostatic in-plane overlap varying energy harvester is modeled and simulated using a circuit simulator. Both linear and nonlinear models are investigated. The nonli- near model includes mechanical stoppers at the displacement extremes. Large amplitude excitation signals, both narrow and wide band, are used to emulate environmental vibrations. Non- linear behavior is significant at large displacement due to the impact

Lars Geir Whist Tvedt; Lars-cyril Julin Blystad; Einar Halvorsen

2008-01-01

98

Treatment of generalized vitiligo in children with narrow-band (TL01) UVB radiation therapy  

Microsoft Academic Search

Background: Only a few clinical trials have been performed on the treatment of generalized vitiligo in children. Recently, narrow-band UVB therapy has been reported to be an effective and safe therapeutic option in adult patients with vitiligo. Objective: We studied the efficacy and safety of UVB (311 nm) therapy in children with generalized vitiligo and evaluated the effect of the

M. D. Njoo; J. D. Bos; W. Westerhof

2000-01-01

99

Novel compact narrow-band band- pass filter (NB BPF) using microstrip closed- loop ring resonators for personal communication systems (PCS's)  

Microsoft Academic Search

In this paper, a novel compact elliptic-function narrow-band band-pass filter is developed using a new configuration of coupled lines to further enhance the coupling strength at the input and output terminals. It is shown that this proposed model provides an effective and beneficial flexibility to control the performance of the filter to realize a narrow-band band-pass filter with improvement in

Mehdi Nosrati

2010-01-01

100

Variable doping narrow-band response GaAlAs photocathode the preparation method of the research  

NASA Astrophysics Data System (ADS)

In order to avoid the low sensitivity common problem of 532nm sensitive narrow-band response photocathode, variable doping narrow-band response GaAlAs photocathode structure is designed. The photocathode is composed of GaAs substrates, Ga1-x1Alx1As buffer layer, Ga1-x2Alx2As doping concentration gradient emissive layer and GaAs protection layer from bottom to top. Among them, exponential doping method is applied to Ga1-x2Alx2As unit layer from the bottom to the top. And a preparation methods of GaAlAs photocathode is developed. For the GaAlAs photocathode components which grow well, chemical cleaning, heating purification and (Cs, O) activation are operated, and ultimately Cs / O activation layer is formed on the surface of Ga1-x2Alx2As doping concentration gradient emissive layer. The highest sensitivity of the photocathode peak response is at 532nm, and the photocathode quantum efficiency in 532nm peaks at 36%.

Xu, Yuan; Chen, XinLong; Zhao, Jing; Wang, Honggang; Chang, BenKang

2012-11-01

101

Development and the role of internal noise in detection and discrimination thresholds with narrow band stimuli  

PubMed Central

The experiments reported here examine the role of internal noise in the detection of a tone in narrow band noise and intensity discrimination for narrow band stimuli in school-aged children as compared to adults. Experiment 1 used 20-Hz wide bands of Gaussian and low-fluctuation noise centered at 500 Hz to assess the role of stimulus fluctuation in detection of a 500-Hz pure tone. Additional conditions tested whether performance was based on level and/or level-independent cues. Children’s thresholds were elevated with respect to adults, and whereas adults benefited from the reduced fluctuation of low-fluctuation noise, children did not. Results from both groups were consistent with the use of a level cue. Experiment 2 estimated intensity increment thresholds for a narrow band Gaussian noise or a pure tone, either with or without a presentation-by-presentation level rove, an additional source of level variability. Stimulus variability was found to have a larger effect on performance of adults as compared to children, a rather counterintuitive finding if one thinks of children as more prone to informational masking introduced by stimulus variability. Both tone-in-noise and intensity discrimination data were consistent with the hypothesis that children’s performance is limited by greater levels of internal noise.

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

2007-01-01

102

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

Code of Federal Regulations, 2012 CFR

...requirements for narrow-band direct-printing (NB-DP) equipment. 80...requirements for narrow-band direct-printing (NB-DP) equipment...476-5 or ITU-R M.625-3 (both incorporated by reference...requirements of ITU-R M.625-3, 1995 (incorporated by...

2012-10-01

103

Validity of the rigid band approximation in the study of the thermopower of narrow band gap semiconductors  

NASA Astrophysics Data System (ADS)

Theoretical studies of thermoelectric properties using ab initio electronic structure calculations help not only to understand existing experimental data but also to predict new materials which can be potentially good thermoelectrics. However, in these studies it is inevitable to employ some approximations. It is therefore important to verify their reliability. To this end, we have investigated the validity of the rigid band approximation (RBA), commonly used in calculating the thermopower (S) in doped (sometimes heavily) narrow band gap semiconductors. We have considered two important systems: half-Heusler HfCoSb and PbTe. We calculate band structures of pure and doped systems [using quasiperiodic approximation (QPA)] by employing the density-functional method. We then use Boltzmann transport theory to calculate the thermopower using both RBA and the band structure with QPA. We find that band structures do not change significantly when isovalent impurities are present excepting in specific cases. However, charged impurities (relevant to the doping case) providing carriers can change the host band structure appreciably. We find that impurities in general remove existing degeneracies which tend to reduce the RBA value of ?S?. The reduction is significant in both HfCoSb and PbTe when charged defects are present.

Lee, Mal-Soon; Mahanti, S. D.

2012-04-01

104

Design of narrow-band Compton scattering sources for nuclear resonance fluorescence  

NASA Astrophysics Data System (ADS)

The design of narrow-band Compton scattering sources for specific applications using nuclear resonance fluorescence (NRF) is presented. NRF lines are extremely narrow (?E/?10-6) and require spectrally narrow sources to be excited selectively and efficiently. This paper focuses on the theory of spectral broadening mechanisms involved during Compton scattering of laser photons from relativistic electron beams. It is shown that in addition to the electron beam emittance, energy spread, and the laser parameters, nonlinear processes during the laser-electron interaction can have a detrimental effect on the gamma-ray source bandwidth, including a newly identified weakly nonlinear phase shift accumulated over the effective interaction duration. Finally, a design taking these mechanisms into consideration is outlined.

Albert, F.; Anderson, S. G.; Gibson, D. J.; Marsh, R. A.; Wu, S. S.; Siders, C. W.; Barty, C. P. J.; Hartemann, F. V.

2011-05-01

105

Design of the miniature waveguide narrow-band band-pass filter in the centimeter range  

Microsoft Academic Search

A new design is proposed and the numerical analysis is conducted for the waveguide band-pass filter with inductive diaphragms. Small dimensions of the filter are achieved due to its partial filling with dielectric having increased dielectric constant (epsiv=41). Adjustment of the filter is provided by movement of special rods of the same dielectrics for compensation of the dispersion of dielectric

A. Galdetskiy; I. Chepurnykh; V. Vasiliev; I. Samsonova

2005-01-01

106

Terahertz narrow-band tune amplification effect in triple-barrier quantum well resonant tunneling nanostructures  

NASA Astrophysics Data System (ADS)

Resonant tunneling diode high-frequency study on the base of proposed quantum models and numerical solution of timedependent Schrödinger equation with open-system boundary conditions in external electromagnetic field are performed for single-quantum well and double-quantum well resonant tunneling structures. As shown the presence of privileged additional level in double-quantum well structures breaks response symmetry, leads to narrow-band frequency selective amplification at frequencies equal to energy spacing between levels in neighbouring quantum wells and to selection of portion of emitter electrons that actively interact with external THz electromagnetic field. The phenomenon results in essentially increase of gain coefficient and opens the possibility of narrow-band amplification frequency tuning in TBRTS in THz range by variation of applied bias voltage.

Kapaev, V. V.; Murzin, V. N.; Savinov, S. A.

2012-10-01

107

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

SciTech Connect

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.

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

108

Monolithic narrow-band filter using ultrahigh-Q tunable active inductors  

Microsoft Academic Search

A tunable active inductor is presented where the novel topology enables both the inductance and series resistance to be varied. With a discrete MMIC realization of this active inductor, Q-factors in excess of 15000 have been measured over a wide range of inductance values. Applications for these active inductors include high-performance narrow-band filters, voltage controlled oscillators, and analog phase shifters.

Stepan Lucyszyn; Ian D. Robertson

1994-01-01

109

Polarization-independent electro-optically tunable narrow-band wavelength filter  

Microsoft Academic Search

We propose and demonstrate the first polarization-independent electro-optically tunable wavelengh filter with single-mode waveguides. The Ti:LiNbO3 filter utilizes narrow-band electro-optic TE ? TM conversion and employs TE\\/TM polarization splitters in the input and output waveguides. The filter operates at 1.52 ?m with a bandwidth of only 12 A? and can be electro-optically tuned over at least 110 A? at a

W. Warzanskyj; F. Heismann; R. C. Alferness

1988-01-01

110

Utility of narrow band imaging for identification of the orifice of the bile duct during ERCP  

Microsoft Academic Search

Exact identification of the orifice of the bile duct in the major duodenal papilla is required for selective cannulation during\\u000a endoscopic retrograde cholangiopancreatography (ERCP). However, there are some cases in which the orifice is unclear. The\\u000a narrow band imaging (NBI) system is an endoscopic imaging technique based on modification of spectral features that enhances\\u000a visualization of the vascular network. On

Hajime Anjiki; Terumi Kamisawa; Naoto Egawa

2010-01-01

111

Measurement of Color Parameters of Psoriatic Plaques by Narrow-Band Reflectance Spectrophotometry and Tristimulus Colorimetry  

Microsoft Academic Search

Color parameters were measured on 50 psoriatic plaques in 10 patients, after scoring the amount of scales on them by inspection, with a narrow-band reflectance spectrophotometer (erythema\\/melanin index expression) and tristimulus colorimeter (CIE L*a*b* expression). Both erythema index and a* (redness) were highest in the group of erythematous plaque with little scale (twice as high as in controls) and decreased

Hirotsugu Takiwaki; Jørgen Serup

1994-01-01

112

Generation of narrow-band terahertz coherent Cherenkov radiation in a dielectric wakefield structure  

Microsoft Academic Search

This study explores the use of a dielectric-lined waveguide structure as a means of producing narrow-band terahertz radiation in the form of electron-beam-driven coherent Cherenkov radiation wakefields. This concept builds on previously studied scenarios such as the Cherenkov maser and the Cherenkov free-electron laser. It is distinct in that it relies solely on coherent wakefield excitation instead of a microbunching

Alan Matthew Cook

2009-01-01

113

Modulation instability of narrow-band nanosecond pulses propagating in anomalous-dispersion fibre  

SciTech Connect

We demonstrate that, in the presence of noise, propagation of narrow-band 100-ns pulses through a 6-km long optical fibre sharply reduces their amplitude when a threshold power ({approx}0.2 W) is exceeded. The effect is due to the development of modulation instability and is sensitive to the noise level in the spectral region {approx}100 GHz in width around the central frequency. (fiber and integrated optics)

Ismagulov, A E; Shelemba, Ivan S [Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Babin, S A; Podivilov, E V; Fedoruk, Mikhail P [Novosibirsk State University, Novosibirsk (Russian Federation); Shtyrina, O V [Institute of Computational Techologies, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

2009-08-31

114

Forced stationary vibrations of flexible plates induced by random narrow-band excitations  

Microsoft Academic Search

We consider some problems related to the analysis of the modes of forced vibrations of elastic plates induced by random narrow-band\\u000a excitations. The investigation of nonlinear vibrations of a plate is performed within the framework of a reduced discrete\\u000a model constructed by using the Hamilton variational principle, finite-element methods, and generalized coordinates. To study\\u000a the dynamical state of the analyzed

V. A. Bazhenov; E. S. Dekhtyaryuk; T. G. Zakharchenko; O. A. Luk'yanchenko; V. F. Imdukh

2000-01-01

115

Narrow-band holographic interference LiNbO 3 -based filters  

Microsoft Academic Search

New experimental data on antiparallel-beam holograms recorded in LiNbO3, temperature fixation of the recorded holographic gratings, and the spectral characteristic of a narrow-band (0.01 nm) interference\\u000a filter are reported. The effects of asymmetry in the diffraction efficiency and the emergence of satellites in the transmission\\u000a spectrum of the filter are observed. These effects are explained using the birefringence properties of

I. F. Kanaev; V. K. Malinovskii; N. V. Surovtsev

2000-01-01

116

Usefulness of a Narrow-Band Reflectance Spectrophotometer in Evaluating Effects of Depigmenting Treatment  

Microsoft Academic Search

.   As a depigmenting treatment, combined topical applications of all-trans retinoic acid (atRA) aqueous gel and 5% hydroquinone,\\u000a 7% lactic acid ointment were used for Oriental patients with hyperpigmented skin lesions such as senile lentigines and nevus\\u000a spilus. A narrow-band reflectance spectrophotometer and a tristimulus colorimeter were used to evaluate objectively the intensity\\u000a of pigmentation and erythema at each clinical

Kotaro Yoshimura; Kiyonori Harii; Yuji Masuda; Motoji Takahashi; Takao Aoyama; Tatsuji Iga

2001-01-01

117

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

Microsoft Academic Search

We study the modulational instability in surface gravity waves with random phase spectra. Starting from the nonlinear Schrödinger equation and using the Wigner-Moyal transform, we study the stability of the narrow-banded approximation of a typical wind-wave spectrum, i.e., the JONSWAP spectrum. By performing numerical simulations of the nonlinear Schrödinger equation we show that in the unstable regime, the nonlinear stage

Miguel Onorato; Alfred Osborne; Renato Fedele; Marina Serio

2003-01-01

118

Narrow band ridge waveguide-to-microstrip transition for low noise amplifier at Ku-band  

Microsoft Academic Search

A compact Ku-band waveguide-to-microstrip transition integrated with low noise amplifier is designed. It acts as an interconnect between waveguide antenna and RF receiver modules. The transition design consists of standard waveguide WR62, a cavity for the low noise amplifier and a solid transformer section in the form of a staircase called ridge. The ridge is fixed in the bottom wall

Zahid Yaqoob Malik; Abdul Mueed; Muhammad Imran Nawaz

2009-01-01

119

Wide and narrow-band bandpass coplanar filters in the W-frequency band  

Microsoft Academic Search

This paper deals with the design of passive coplanar devices in the W-frequency band. As long as coplanar transmission lines are correctly dimensioned, analytical models based on quasi-TEM approximation can be used. Such models are associated with a correct definition of the reference planes at the junctions and employed for junction discontinuities, T- and cross-junctions. In order to validate these

Eric Rius; Gaëtan Prigent; Henri Happy; Gilles Dambrine; Samuel Boret; Alain Cappy

2003-01-01

120

The Multi-Band Emission Profile in GRB  

NASA Astrophysics Data System (ADS)

Gamma-ray burst (GRB) light curves generally are energy dependent, i.e., the higher the photon energy, the narrower the pulse. In addition, the peak of the pulse at lower energies is usually delayed compared with that in higher energy. The phenomenon even exists in some X-ray flares and following optical flares. However, its origin is still unclear. Here we calculate the emission in different bands produced from different-thickness shocked shell due to radiative cooling, with the equal arrival time volume effect considered. We find the emission profile is energy dependent and that the light curves show spectral lag, which are consistent with the observations. This can be an explanation of the energy dependence of light curve and spectral lag in GRB, X-ray flare and following optical flare.

Zhao, X.-H.; Bai, J.-M.

2013-07-01

121

Wide-Band Spectra of Prompt Emission  

NASA Astrophysics Data System (ADS)

The Fermi observatory has detected GeV photons from several GRBs. Some of them show an extra spectral component, which is a hint for emission mechanism of GRBs. Here we discuss the GeV emission mechanism according to several promising models. The difference between models will appear in temporal evolution of the photon spectrum. To verify this, instruments that can obtain high photon statistics like CTA are desired. We also discuss the photosphere model, which is recently supported by wide-band observations with Fermi.

Asano, K.

2013-07-01

122

Narrow band 390 nm emitting phosphors for photoluminescent liquid crystal displays  

NASA Astrophysics Data System (ADS)

Photoluminescent liquid crystal displays use a liquid crystal to modulate the intensity of ultraviolet light incident on visible emissive phosphors. In order to gain optimum performance from the liquid crystal in such a device, the activating light must cover a narrow spectral bandwidth very near to the visible (violet) region of the spectrum. Calcium sulphate europium phosphor offers an emission spectrum closely matching these requirements and has been incorporated inside low pressure mercury cold cathode fluorescent lamps. These have been used to backlight a photoluminescent liquid crystal display demonstrator.

Vecht, A.; Newport, A. C.; Bayley, P. A.; Crossland, W. A.

1998-10-01

123

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

SciTech Connect

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

Wang, J.; Mao, Y. F.; Wei, J. Y., E-mail: wj@bao.ac.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100021 (China)

2011-11-01

124

5f-band narrowing in UX/sub 3/B compounds: evidence from resonant photoemission. [X = Ru or Rh  

SciTech Connect

Resonant photoemission at the uranium 5d disorption edge has been used to determine the 5f emission in URu/sub 3/, URh/sub 3/, URu/sub 3/B, and URh/sub 3/B polycrystalline samples. The observed 5f band narrowing (from 2.0 to 1.5 eV as one goes from URu/sub 3/ to URu/sub 3/B, and from 2.8 to 1.1 eV for URh/sub 3/ and URh/sub 3/B respectively) is explained as due to a decrease in the f-d hybridization between uranium and rhodium (ruthenium) atoms.

Zolnierek, Z.; Arko, A.J.; Koelling, D.D.

1985-10-01

125

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

PubMed

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

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

2008-05-01

126

Narrow-band photoreceiver OEIC on InP operating at 38 GHz  

Microsoft Academic Search

We report on the successful monolithic integration of an InP-based photoreceiver operating in the narrow band around 38 GHz at a wavelength of 1.55 ?m, The optoelectronic integrated circuit (OEIC) incorporates two types of high-speed devices, a submicrometer metal-semiconductor-metal photodetector (MSM PD) made of InGaAs-InP and quarter-micrometer high-electron-mobility-transistors (HEMTs) based on a lattice-matched InGaAs-InAlAs-InP layer stack. For this purpose a

T. Engel; A. Strittmatter; W. Passenberg; A. Umbach; W. Schlaak; E. Droge; A. Seeger; R. Steingruber; G. C. Mekonnen; G. Unterborsch; H.-G. Bach; E. H. Bottcher; D. Bimberg

1998-01-01

127

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

SciTech Connect

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)

Kraiskii, A V; Mironova, T V; Sultanov, T T [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2010-09-10

128

AGAR-AGAR: a high-efficiency narrow-band imager for ELTs  

NASA Astrophysics Data System (ADS)

The thinking about possible instruments for the future ELTs has just started and the current phase allows to pursue non-traditional solutions. Following the guidelines of the Science Case for an ELT1,2 our team searched for possible intersections with innovative technologies we currently deal with in our research. We found that Volume Phase Holographic Gratings and advanced dichroics could be suited to design a non-traditional narrow band imager. We propose in this paper a comparative analysis of a VPHG based and a dichroic based configurations for the imager.

Tresoldi, Daniela; Felletti, Riccardo; Bianco, Andrea; Conconi, Paolo; De Caprio, Vincenzo; Crimi, Giuseppe; Molinari, Emilio; Riva, Alberto; Riva, Marco; Spanò, Paolo; Tintori, Matteo; Toso, Giorgio; Zerbi, Filippo M.

2006-07-01

129

Efficient Phase-Encoding Quantum Key Generation with Narrow-Band Single Photons  

NASA Astrophysics Data System (ADS)

We propose an efficient phase-encoding quantum secret key generation scheme with heralded narrow-band single photons. The key information is carried by the phase modulation directly on the single-photon temporal waveform. We show that when the technique is applied to the conventional single photon phase-encoding BB84 and differential phase shift (DPS) quantum key distribution schemes, the key generation efficiencies can be improved by factors of 2 and 3, respectively. For N(>=3)-period DPS systems, the key generation efficiency can be improved by a factor of N. The technique is suitable for quantum-memory-based long-distance fiber communication systems.

Yan, Hui; Zhu, Shi-Liang; Du, Sheng-Wang

2011-07-01

130

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

PubMed

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

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

2003-04-21

131

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

NASA Astrophysics Data System (ADS)

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.

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

132

NPP VIIRS emissive band radiance calibration  

NASA Astrophysics Data System (ADS)

VIIRS thermal emissive bands (TEB) calibration data (blackbody and space counts) have been analyzed. The analysis results indicate that the Visible Infrared Imaging Radiometer Suite (VIIRS) TEB is stable and exceeds the specification. VIIRS Blackbody temperature is stable, too. The 6 platinum resistance thermometers (PRT) are also stable, except for the 3rd and 6th PRT have a periodic variation of 50 mK. Using the calibration data during the Blackbody temperature cool down and warm up, we found that noise equivalent deviation of temperatures (NEdT) varies with the Blackbody temperature. We developed a model that can predict the scene temperature dependent NEdT for the VIIRS M15 band. Comparisons between the VIIRS and other sensors such as AVHRR, MODIS and CrIS demonstrated that VIIRS TEB agrees generally with those sensors.

Liu, Quanhua; Cao, Changyong; Weng, Fuzhong

2012-09-01

133

High-accuracy, compact database of narrow-band k-distributions for water vapor and carbon dioxide  

NASA Astrophysics Data System (ADS)

An accurate and compact narrow-band k-distribution database has been constructed for water vapor and carbon dioxide from the HITEMP and CDSD-1000 spectroscopic databases. The systematic approach of k-distribution data generation and compaction, storage optimization and interpolation is discussed in this paper. The new database enables the user to obtain narrow-band, part-spectrum and full-spectrum k-distributions for inhomogeneous gas mixtures.

Wang, Anquan; Modest, Michael F.

2005-06-01

134

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

Microsoft Academic Search

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

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

135

Electrically driven, narrow-linewidth blackbody emission from carbon nanotube microcavity devices  

NASA Astrophysics Data System (ADS)

We report electrically driven narrow-linewidth blackbody emission from carbon-nanotube with Fabry-Perot microcavities. We fabricated two types of devices with microcavities consisting of either gold mirrors or distributed Bragg reflectors (DBR). Gold-mirror microcavity devices exhibit blackbody emission with narrowed full-width at half-maximum of ~50 nm in contrast to the broad normal blackbody emission spectrum. The spectra from these devices can be explained by theoretical calculations accounting for the temperature-dependent intrinsic blackbody spectra and transmittance spectrum of the microcavity. Moreover, the DBR microcavity devices show a narrower resonant peak inside the photonic bandgap, compared with the gold-mirror microcavity device.

Fujiwara, M.; Tsuya, D.; Maki, H.

2013-09-01

136

Effect of amplitude modulation coherence for masked speech signals filtered into narrow bands  

NASA Astrophysics Data System (ADS)

Introduction of masker amplitude modulation (AM) can improve signal detection in a number of paradigms. In some cases this advantage depends on the coherence of modulation across a relatively wide frequency range. In the experiments described below, observers were asked to identify masked spondee words produced by a single male talker. The target spondees and masking noise were filtered into nine narrow bands, and the coherence of AM of either the speech signal or noise masker was manipulated. Inherent modulation of the masker bands was manipulated via assignment of real and imaginary values to the associated components of each band in the frequency domain, and AM of speech bands was achieved via multiplication with envelopes extracted from these maskers. Responses were based on two alternatives, four alternatives, or open response sets. The effect of masker AM coherence was highly dependent upon the size of the response set: coherent AM was associated with better thresholds in a two-alternative response set, but poorer thresholds in an open response set. Results with AM speech did not depend critically upon the across-frequency temporal synchrony of AM imposed on the speech material.

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

2003-01-01

137

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

SciTech Connect

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

Sargsyan, A.; Mirzoyan, R.; Sarkisyan, D., E-mail: david@ipr.sci.am [National Academy of Sciences of Armenia, Institute for Physical Research (Armenia)

2012-11-15

138

Near-infrared narrow-band imaging of gold/silica nanoshells in tumors  

NASA Astrophysics Data System (ADS)

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.

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.

2009-03-01

139

A Cooperative Distance Learning Method based on the Narrow-band Internet and Its Evaluation  

NASA Astrophysics Data System (ADS)

This paper describes the experimental evaluation of a cooperative distance learning method, which can be utilized on the narrow-band Internet. In this method, students of group-learning perform a series of study a couple of times, which create an on-line report, communicating through the chat about given theme. they try to gain improvement in the study effect with higher cooperative attitude. Teacher gives a short lecture at the first stage, and then gives supplementary explanation after grasping the degree of comprehension of students at the middle stage of the study. Teaching materials are distributed to students' PCs beforehand and the lecture could be carried out on the narrow-band environment by transmitting the commands. The teacher analyzes students' communication logs and gives advice for the next study. This paper describes the result of the evaluation of the proposed method by carrying out simulated installation of the environment within the campus supposing a trial of cooperative distance learning in overseas desert circumference area environment.

Tilwaldi, Dilmurat; Takahashi, Toshiya; Takata, Akinobu; Koizumi, Hisao

140

WFPC2 Narrow-Band HAlpha Imaging of the Edge-on Galaxy NGC4631  

NASA Astrophysics Data System (ADS)

Observations of nearby edge-on disk galaxies are essential to determine the role that the disk/halo interaction has in galaxy evolution. Located in a direction of exceptionally low Galactic extinction, NGC4631 is particularly suitable for a multi-wavelength investigation of extra-planar gas components. In fact, NGC4631 is one of the most well studied late-type disk galaxies. Broad-band optical, near-infrared, near-UV, and far-UV observations have been {or will be} taken with HST and FUSE. We have obtained AXAF observing time to conduct a spatially-resolved X-ray spectroscopic observation of the galaxy. Here we propose for HST WFPC2 narrow-band H-alpha imaging of the galaxy's active central region. This image will enable us to resolve various narrow filaments of warm ionized gas that extend more than 2 kpc away from the mid-plane of the galaxy. Based on the geometry, filling factor and line intensity of the filaments and their correlation with X-ray- emitting gas, we will stu dy their origins {chimney walls, b listers, condensations of cooled hot gas, shocks, etc}. The results will be invaluable for our understanding of similar extra-planar gas observed in the Milky Way and other galaxies.

Wang, Q.

1999-07-01

141

Molecular encapsulation of fluorescent dyes affords efficient narrow-band dye laser operation in water.  

PubMed

A water-based narrow-band high-efficiency dye laser was designed by means of a supramolecular host-guest chemical approach. The lasing characteristics of rhodamine B and sulforhodamine B (Kiton Red S) dyes in aqueous solution with the macrocyclic host cucurbit[7]uril (CB7) as additive were investigated in a narrow-band dye laser setup. Significant improvements in both photostability and thermo-optical properties of the aqueous CB7-complexed dye systems were observed as compared to the uncomplexed dyes in ethanol solution. The tuning curves for the new dye-CB7-water systems were constructed by measuring the laser output at different wavelengths, which showed similar peak efficiencies and red-shifted gains compared to the ethanolic solutions of the dyes, while dye laser operation revealed comparable pump threshold energies and slope efficiencies. The combined results render the dye-CB7-water system an attractive active medium for high-repetition rate dye laser operation. PMID:20839271

Mohanty, Jyotirmayee; Jagtap, Krishna; Ray, Alok K; Nau, Werner M; Pal, Haridas

2010-10-25

142

Polaron transport in quasi-1d organic conductors and in some narrow band systems  

NASA Astrophysics Data System (ADS)

A detailed review of large and small polaron transport theory in quasi-1d organic conductors and conducting polymers, and in some narrow band systems including superlattices, superionic conductors and superconductors with heavy fermions is presented. The strong-coupling large polaron mobility is evaluated in 1d and 3d crystals taking account of optical phonon dispersion. The current-voltage characteristics (CVC) for a a 1d acoustic polaron with saturation of the drift velocity V0(E) in strong fields E-->? near the sound velocity S is found. This effect has been recently observed by Donovan and Wilson in polydiacetylene PDA TS [8]. The small polaron (SP) spectrum in narrow band conductors is investigated and its strong anisotropy in quasi-1d organic conductors is proved. The CVC for SP is calculated and the characteristic maximum with the negative differential conductivity is found. An exact theory of the Gunn effect in these 1d systems is developed and the explicit analytic expressions for a domain structure are obtained. The domain stability is studied and the possibility of their experimental observing is discussed. In conclusion I wish to thank A.S. Alexandrov, V.L. Bonch-Bruevich, S.A. Brazovsky, Yu.A. Firsov, I.B. Levinson, A.A. Ovchinnikov, E.I. Rashba, R.A. Suris and G.E. Volovik for useful discussions of some problems, considered in the present review.

Gogolin, A. A.

1988-01-01

143

Ultraviolet to Infrared Continuum of Narrow Emission Line Active Galaxies.  

National Technical Information Service (NTIS)

The overall continua of nine narrow line active galaxies are presented from the UV to the far IR. The nonstellar IR distribution is clearly not an extrapolation of the UV and optical spectra. The nonstellar components include a nonthermal power law contin...

C. Boisson F. Durret

1986-01-01

144

A COMPARISON OF THE PERFORMANCE OF A BRAND OF BROAD-BAND AND SEVERAL BRANDS OF NARROW-BAND BAT DETECTORS IN TWO DIFFERENT HABITAT TYPES  

Microsoft Academic Search

The use of bat detectors to monitor bat activity is common. Although several papers have compared the performance of different brands, none have dealt with the effect of different habitats nor have they compared narrow- and broad-band detectors. In this study the performance of four brands of ultrasonic bat detector, including three narrowband and one broad-band model, were compared for

S. PARSONS

1996-01-01

145

Synchrotron studies of narrow band materials. Progress report, July 1, 1990--June 30, 1993  

SciTech Connect

Objective was to determine the single-particle electronic structure of selected narrow band materials in order to understand the relation between their electronic structures and novel low energy properties, such as mixed valence, heavy Fermions, Kondo effect, insulator-metal transitions, non-Fermi liquid behavior, and high-temperature superconductivity. This program supports photoemission spectroscopy (PES) at various synchrotrons. The progress is reported under the following section titles: ZSA (Zaanen-Sawatzky-Allen) systematics and I-M transitions in 3d transition metal oxides, insulator-metal transitions in superconducting cuprates, Fermi liquid and non-Fermi liquid behavior in angular resolved PES lineshapes, heavy-Fermion and non-Fermi liquid 5f electron systems, and Kondo insulators.

Allen, J.W.

1993-02-01

146

Narrow-band spectroscopic source of coherent radiation, tunable in the mid-IR range  

SciTech Connect

A description is given of a repetitively pulse source of narrow-band coherent radiation with continuous frequency tuning in the ranges 1.5-1.85 {mu}m and 2.5-3.7 {mu}m, and with energies per pulse up to 8 and 3 mJ, respectively. The source is based on parametric amplification of a weak IR signal from a difference-frequency generator or from a single-mode optical parametric oscillator. This source was used to determine the spectra of IR absorption and of degenerate four-wave mixing, as well as the spectra of excitation of stimulated resonance Raman scattering of light in some molecules under static or supersonic jet conditions. (nonlinear optical phenomena and devices)

Marquez, J; Voelkel, D; Huisken, F [Max-Plank Institut fur Stromungsforschung, Gottingen (Germany); Orlov, Sergei N; Polivanov, Yurii N; Smirnov, Valery V; Chuzavkov, Yu L [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

1998-02-28

147

Limits on Production of Narrow Band Photons from Inverse Compton Scattering  

SciTech Connect

In using the inverse Compton scattering (ICS) interaction as a high brilliance, short wavelength radiation source, one collides two beams, one an intense laser, and the other a high charge, short pulse electron beam. In order to maximize the flux of photons from ICS, one must focus both beams strongly, which implies both use of short beams and the existence of large angles in the interaction. One aspect of brilliance is the narrowness of the wavelength band emitted by the source. This paper explores the limits of ICS-based source brilliance based on inherent wavelength broadening effects that arise due to focal angles, laser energy density, and finite laser pulse length effects. It is shown that for a nominal 1% desired bandwidth, that one obtains approximately one scattered photon per electron in a head-on collision geometry.

Rosenzweig, J.; Williams, O. [UCLA Dept. of Physics and Astronomy, 405 Hilgard Ave., Los Angeles, CA 90034 (United States)

2006-11-27

148

Responses of discretized systems under narrow band nonstationary random excitations. Part 2: nonlinear problems  

NASA Astrophysics Data System (ADS)

In a companion paper, the extended stochastic central difference (ESCD) method was presented for computation of responses of linear multi-degrees-of-freedom (mdof) systems under narrow band stationary and nonstationary random excitations. The present paper is concerned with the generalization of the ESCD method for computation of nonlinear mdof systems. The generalization is based on a combination of the ESCD method with statistical linearization (SL) technique, modified adaptive time scheme (ATS), and time coordinate transformation (TCT). Unlike the conventional SL technique, the generalized ESCD method is applicable to mdof systems with large nonlinearities. Comparison is made of the computed results applying the generalized ESCD method to those obtained by the Monte Carlo simulation (MCS). Excellent agreements were obtained. It was observed that the proposed method is very efficient compared with the MCS.

Chen, Z.; To, C. W. S.

2005-10-01

149

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

SciTech Connect

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

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

2008-03-18

150

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

SciTech Connect

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

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

2008-03-18

151

Water vapor transmittance models for narrow bands in the 13 to 19. mu. m spectral region  

SciTech Connect

The purpose of this report is to document the development of water vapor transmittance models for narrow bands (satellite sensor channels) in the 13 to 19 ..mu..m spectral region. The models are the result of research efforts of the author in 1971-1972 while on active duty with the US Air Force at the Air Force Global Weather Central (AFGWC). The models were developed for application in studies involving a temperature profiling sensor system carried aboard the satellites of the Defense Meteorological Satellite Program (DMSP), formerly DAPP. Recently, (Lovill et al., 1978; Luther et al., 1981) the models were implemented for studies concerned with methodologies to retrieve total atmospheric column ozone from measurements of newer DMSP Block 5D series satellite sensors with similar channels (see Nichols, 1975).

Weichel, R.L.

1983-10-01

152

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

PubMed Central

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.

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

2007-01-01

153

MODIS thermal emissive band detector bias  

NASA Astrophysics Data System (ADS)

Two nearly identical MODIS instruments are currently operating in space: one on the Terra spacecraft launched in December 1999 and another on the Aqua spacecraft launched in May 2002. MODIS has a total of 36 spectral bands, 16 of which are the Thermal Emissive Bands (TEB) with wavelengths covering from 3.7?m to 14.4?m. Each TEB has 10 detectors aligned in the along-track direction with a spatial resolution of 1km. The 10 detectors view the Earth each scan over a 2330km wide swath. The curvature of the Earth creates a bowtie effect with each scan. At large scan angles consecutive scans will have several detectors with overlapping fields of view. This paper applies two approaches to investigate any potential bias between the 10 detectors of any TEB. A histogram approach is applied to large relatively uniform scenes over the Antarctic plateau, ocean and desert. Results are compared with an approach using the sets of matched detector pairs due to the bowtie effect. Terra and Aqua MODIS TEB long term trends in detector biases are presented and discussed.

Wenny, B. N.; Geng, X.; Xiong, X.

2009-09-01

154

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

NASA Astrophysics Data System (ADS)

We search for marginal Fermi-liquid behavior [1] 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 [2] 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) ˜ T 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 {*/ 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 {*/ 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 [3]. Such behavior of resistivity could be relevant for some uranium-based heavy-fermion compounds like UNi2Al3 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 [4] 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.

Kagan, M. Yu.; Val'kov, V. V.

2011-07-01

155

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

NASA Astrophysics Data System (ADS)

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

Jo, Youngho; Wu, Dapeng

2009-05-01

156

Energy transport in weakly nonlinear wave systems with narrow frequency band excitation.  

PubMed

A novel discrete model (D model) is presented describing nonlinear wave interactions in systems with small and moderate nonlinearity under narrow frequency band excitation. It integrates in a single theoretical frame two mechanisms of energy transport between modes, namely, intermittency and energy cascade, and gives the conditions under which each regime will take place. Conditions for the formation of a cascade, cascade direction, conditions for cascade termination, etc., are given and depend strongly on the choice of excitation parameters. The energy spectra of a cascade may be computed, yielding discrete and continuous energy spectra. The model does not require statistical assumptions, as all effects are derived from the interaction of distinct modes. In the example given-surface water waves with dispersion function ?(2)=gk and small nonlinearity-the D model predicts asymmetrical growth of side-bands for Benjamin-Feir instability, while the transition from discrete to continuous energy spectrum, excitation parameters properly chosen, yields the saturated Phillips' power spectrum ~g(2)?(-5). The D model can be applied to the experimental and theoretical study of numerous wave systems appearing in hydrodynamics, nonlinear optics, electrodynamics, plasma, convection theory, etc. PMID:23214551

Kartashova, Elena

2012-10-17

157

Emission gain narrowing from single crystals of a thiophene/phenylene co-oligomer  

NASA Astrophysics Data System (ADS)

Emission gain narrowing has been observed for single crystals of a thiophene/phenylene co-oligomer. The hexagon flake crystals were placed on a quartz substrate with the crystals' face in close contact with the substrate plane. These crystals were irradiated with a N2 laser with a 337.1 nm wavelength at a repetition rate 10 Hz that tuned its intensity to 100-1150 ?J/cm2. The emission gain narrowing takes place at 21490 (465.4 nm) and 20220 cm-1 (494.5 nm) with increased intensities, with their half width at half maxima reaching ~50 cm-1. On the basis of the nonlinear relationship between the emission peak intensities and the laser light intensity, the gain narrowing has been attributed to the amplified spontaneous emission.

Nagawa, Michifumi; Hibino, Ryota; Hotta, Shu; Yanagi, Hisao; Ichikawa, Musubu; Koyama, Toshiki; Taniguchi, Yoshio

2002-01-01

158

Narrow-band ultraviolet B as a potential alternative treatment for resistant psychogenic excoriation: an open-label study.  

PubMed

Narrow-band ultraviolet therapy has been used successfully for the treatment of inflammatory skin disorders and generalized pruritus. We have prospectively evaluated seven consecutive patients with resistant psychogenic excoriation (PE) treated with narrow-band ultraviolet B (NB-UVB). Approximately 70% of all patients showed improvement in their condition. NB-UVB therapy was well tolerated, with no serious side effects. We may conclude that, when treating a patient with PE, NB-UVB in combination with other approaches may provide extra benefit in resistant cases. PMID:20584258

Ozden, Müge Güler; Aydin, Fatma; Sentürk, Nilgün; Bek, Yüksel; Cantürk, Tayyar; Turanli, Ahmet Ya?ar

2010-06-01

159

An investigation of the 3 micron emission bands in planetary nebulae  

NASA Astrophysics Data System (ADS)

Spectra are presented of 21 planetary nebulae spanning the well-known, but still unidentified, narrow emission features at 3.2-3.6 micron. The equivalent width of the 3.29 micron emission band is strongly correlated with the gas-phase carbon to oxygen ratio, as expected for a band origin in carbon-rich grains or molecules. It displays an approximately linear dependence upon the C/O ratio with a threshold near C/O approx. 0.6. The emission band is present in 18 of the 21 nebulae, being absent in 3 of 6 O-rich objects and only weakly present in a fourth. The profile of the 3.29 micron band is closely similar in all of the nebulae and distinct from the band profile seen in some stellar envelopes. Weaker emission features in the 3.4-3.5 micron region are detected in nine objects, and are prominent only in nitrogen-rich type I nebulae. The intensity of the 3.4 micron feature in these objects is correlated with that of the 3.29 micron band, while the ratio of the two bands is strongly correlated with the nitrogen abundance. Possible explanations for this behavior are discussed.

Roche, P. F.; Aitken, D. K.; Smith, C. H.; Hoare, M. G.; Lucas, P. W.

1996-01-01

160

Candidates for Intracluster Planetary Nebulae in the Virgo Cluster Based on the Suprime-Cam Narrow-Band Imaging in [O III] and H?  

NASA Astrophysics Data System (ADS)

We have identified 38 candidates of intracluster planetary nebulae (ICPNe) in a 34' × 27' field in the core of the Virgo cluster based on Suprime-Cam imaging through two narrow-band filters centered at redshifted wavelengths of the [O III] ?=5007Å and the H? ?=6563Å lines. Broad-band images in the V and R bands are used to check for any emissions in the adjacent continuum. We describe the method briefly and present a list of the intracluster planetary nebula candidates, together with their finding charts. The ICPN candidates show a highly inhomogeneous distribution, which may suggest an association with the M 86-M 84 subcluster. The fraction of diffuse intracluster light with respect to the total light in galaxies is estimated to be about 10%, leading to an estimate of about 20% for the baryon fraction. A spectroscopic follow up and a wider survey are critical to reveal the nature of the intracluster stellar population.

Okamura, Sadanori; Yasuda, Naoki; Arnaboldi, Magda; Freeman, Kenneth C.; Ando, Hiroyasu; Doi, Mamoru; Furusawa, Hisanori; Gerhard, Ortwin; Hamabe, Masaru; Kimura, Masahiko; Kajino, Toshitaka; Komiyama, Yutaka; Miyazaki, Satoshi; Nakata, Fumiaki; Napolitano, Nicola R.; Ouchi, Masami; Pannella, Maurilio; Sekiguchi, Maki; Shimasaku, Kazuhiro; Yagi, Masafumi

2002-12-01

161

Reabsorption, band-gap narrowing, and the reconciliation of photoluminescence spectra with electrical measurements for epitaxial n-InP  

Microsoft Academic Search

The effects of reabsorption and band-gap narrowing (BGN) on experimental photoluminescence (PL) spectra of n-InP grown by metalorganic chemical vapor deposition are analyzed. PL spectra show a pronounced widening of the main PL peak and a shift of that peak to higher photon energy with increasing doping due to band filling. However, the magnitude of these effects, both here and

R. M. Sieg; S. A. Ringel

1996-01-01

162

Speaker identification by difference sum and correlation coefficients of narrow-band spectrum  

NASA Astrophysics Data System (ADS)

Some problems in speaker identification procedures were examined: transformation of acoustic parameters into auditory scales, invalid measurement values, and comparability of spectral energy values across the frequency range. To resolve those problems, the acoustic spectral energy of three Korean numbers produced by ten female students from narrow-band spectrograms at 19 proportional time points of each voiced segment were analyzed. Then, cells of the first five spectral matrices were averaged to form a matrix model for each speaker. The correlation coefficients and sum of the absolute amplitude difference in each pair of the spectral models of the ten subjects were obtained. Also, some individual matrix models were compared to those of the same subject or the other subject with a similar spectral model. Results showed that in numbers ``2'' and ``9'' subjects could not be clearly distinguished from the others but in number ``4'' it shed some possibility of setting threshold values for speaker identification if the coefficients and the sum of absolute difference were employed. Further studies would be desirable on various combinations of the range of long-term average spectra and the degree of signal pre-emphasis. [Work supported by grant No. R01-1999-000-00229-0 from the Korea Science & Engineering Foundation.

Yang, Byunggon; Kang, Sunmee

2003-04-01

163

Optical Diagnosis of Small Colorectal Polyp Histology with High-Definition Colonoscopy Using Narrow Band Imaging  

PubMed Central

Optical diagnosis of polyp histology can potentially result in enormous cost savings by way of the "resect and discard" strategy for diminutive polyps and the "do not resect" strategy for diminutive hyperplastic polyps in the distal colon. Narrow Band Imaging (NBI) highlights the surface mucosal and vascular pattern on polyps and has been shown to accurately characterize adenomatous and hyperplastic polyps by experts. However, the results have been a little discouraging amongst lesser experienced endoscopists. Studies have also shown that using the NBI diagnosis of diminutive polyp histology, experts can accurately define the future surveillance colonoscopy intervals. However nonexperts in academic or community setting have as yet failed to achieve the recommended thresholds. The subjectivity in assessment by endoscopists leads to the variable accuracy rates and can be circumvented by computer based automated tools. Although initial experience with a few computer based algorithms have shown accuracies comparable to experts, further refinement and validation will be required before these can be implemented in clinical practice. Incorporation of optical diagnosis of diminutive polyps into clinical practice is bound to face several hurdles. But the potential for enormous cost saving makes it an attractive strategy that can make colonoscopy more cost effective.

2013-01-01

164

Narrow band pulses as stimuli in an auditory brain stem recording study with a harbor porpoise  

NASA Astrophysics Data System (ADS)

We have studied several aspects of hearing by a harbor porpoise using the ABR method with pulsed stimuli. Experiments were conducted on a male porpoise in collaboration with Fjord and Baelt, Kerteminde, Denmark. The animal had suction cups containing silver electrodes placed near the blowhole and near the dorsal fin. When fitted with the electrodes he moved to an underwater listening post where his outgoing sonar signal could be used to trigger a phantom echo. EEG signals were amplified differentially and averaged over a variable number of presentations depending on trial duration and experiment. For studying the frequency/intensity response, narrow band pulsed stimuli were generated and presented in several ways. One way was to use the impulse response of a B&K 1/3 octave filter bank (set to 80, 100, 125, or 160 kHz) as a stimulus. This stimulus was presented in both a passive hearing task, when a signal generator triggered the echo, and in an active experiment, where the echo was time locked to the animals emitted signal. Our results show the best response at 125 kHz and indicate a slight, but significantly higher response in the active mode. The latter has a methodological explanation. [Work supported by ONR.

Beedholm, Kristian; Miller, Lee A.

2005-04-01

165

Correlation of Narrow Band Imaging with Magnifying Colonoscopy and Histology in Colorectal Tumors  

PubMed Central

Background/Aims Narrow band imaging (NBI) is a new technique that uses optical filters for imaging of mucosal morphology. The aim of this study was to correlate findings of NBI with magnifying colonoscopy and histology for prediction of neoplastic colorectal lesion. Methods Between September 2005 and December 2007, 107 colon polyps from 68 patients were detected by conventional colonoscopy and subsequently evaluated by NBI with magnifying colonoscopy and analyzed for a pit pattern and a capillary pattern. More analysis was done regarding thickness and irregularity of capillary features. Results Pit pattern with NBI magnification to discriminate between neoplastic and non-neoplastic lesions had a sensitivity of 88.9% and a specificity of 87.5%; capillary pattern yielded test performance characteristics of 91.9% and 87.5%. In respect of capillary thickness, invisible capillaries were found significantly more often in hyperplastic lesions. All thick capillaries were found in neoplastic polyps, and found significantly more often in carcinomas with submucosal massive invasion (sm-m) (p<0.01). In respect of capillary irregularity, invisible capillaries were found significantly more often in hyperplasic lesions, and severely irregular capillaries were found significantly more often in sm-m lesions (p<0.01). Conclusions Observation of capillary thickness and irregularity by NBI magnification is useful for correlating histological grade with carcinoma, especially with depth of submucosal invasion.

Yoo, Hee Yong; Ko, Bong Min; Kim, Hee Kyung; Ahn, Hyung Su; Han, Seung Hyo; Bae, Jun Yong; Min, Seul Ki; Lee, Jong Chan; Ryu, Chang Beom

2011-01-01

166

Three-step H- charge exchange injection with a narrow-band laser  

NASA Astrophysics Data System (ADS)

This paper presents a scheme for three-step laser-based stripping of an H- beam for charge exchange injection into a high-intensity proton ring. First, H- atoms are converted to H0 by Lorentz stripping in a strong magnetic field, then neutral hydrogen atoms are excited from the ground state to upper levels by a laser, and the remaining electron, now more weakly bound, is stripped in a strong magnetic field. The energy spread of the beam particles gives rise to a Doppler broadened absorption linewidth, which makes for an inefficient population of the upper state by a narrow-band laser. We propose to overcome this limitation with a “frequency sweeping” arrangement, which populates the upper state with almost 100% efficiency. We present estimates of peak laser power and describe a method to reduce the power by tailoring the dispersion function at the laser-particle beam interaction point. We present a scheme for reducing the average power requirements by using an optical ring resonator. Finally, we discuss an experimental setup to demonstrate this approach in a proof-of-principle experiment.

Danilov, V.; Aleksandrov, A.; Assadi, S.; Henderson, S.; Holtkamp, N.; Shea, T.; Shishlo, A.; Braiman, Y.; Liu, Y.; Barhen, J.; Zacharia, T.

2003-05-01

167

A Narrow-band Multispectral Instrument for the Measurement of Low Density Biomass  

NASA Astrophysics Data System (ADS)

During 2001, a team of scientists and engineers from NASA Goddard Space Flight Center, at the request of NASA Headquarters, lead a planning activity for future studies of the sources, sinks, and transport of carbon in the atmosphere, on land, and in the oceans. One outcome of this study was a survey of critical gaps in our current measurement suite and identification of the types of instruments that could provide this missing information. Estimating biomass in ecosystems dominated by vegetation of short-stature (< 5 m), such as grasslands and shrub lands, was one of the gaps identified. An instrument with multiple narrow bands in the visible and near infrared was one possibility for filling this gap. In addition, such an instrument might prove helpful in conjunction with lidar measurements for characterizing high density biomass ecosystems such as tropical and boreal forest. A summary of the study and the basis for the recommendations will be presented. The characteristics of a low density biomass instrument, including measurement specifications and considerations, design alternatives including full VNIR and SWIR spectral coverage, and possible spacecraft accommodations, will be discussed. One or more aircraft versions of this type of instrument could be flown as part of the North American Carbon Program's field campaign. This could test the current specifications and design alternatives, thereby helping to guide selection of the best approach for a possible spaceborne instrument, as well as provide valuable information for the campaign itself.

Gervin, J. C.; Knox, R. G.; Hall, F. G.; McClain, C. R.; Caruso, P. S.

2002-12-01

168

Non-sequential narrow band imaging for targeted biopsy and monitoring of gastric intestinal metaplasia  

PubMed Central

AIM: To evaluate the efficacy of non-sequential narrow band imaging (NBI) for a better recognition of gastric intestinal metaplasia (GIM). METHODS: Previously diagnosed GIM patients underwent targeted biopsy from areas with and without GIM, as indicated by NBI, twice at an interval of 1 year. The authors compared the endoscopic criteria such as light blue crest (LBC), villous pattern (VP), and large long crest (LLC) with standard histology. The results from two surveillance endoscopies were compared with histology results for sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and likelihood ratio of positive test (LR+). The number of early gastric cancer cases detected was also reported. RESULTS: NBI targeted biopsy was performed in 38 and 26 patients during the first and second surveillance endoscopies, respectively. There were 2 early gastric cancers detected in the first endoscopy. No cancer was detected from the second study. Surgical and endoscopic resections were successfully performed in each patient. Sensitivity, specificity, PPV, NPV, and LR+ of all 3 endoscopic criteria during the first/second surveillances were 78.8%/91.3%, 82.5%/89.1%, 72.8%/77.8%, 86.8%/96.1, and 4.51/8.4, respectively. LBC provided the highest LR+ over VP and LLC. CONCLUSION: Non-sequential NBI is useful for GIM targeted biopsy. LBC provides the most sensitive reading. However, the optimal duration between two surveillances requires further study.

Rerknimitr, Rungsun; Imraporn, Boonlert; Klaikeaw, Naruemon; Ridtitid, Wiriyaporn; Jutaghokiat, Sukprasert; Ponauthai, Yuwadee; Kongkam, Pradermchai; Kullavanijaya, Pinit

2011-01-01

169

A dual Fabry-Perot based narrow band imager for the National Large Solar Telescope  

NASA Astrophysics Data System (ADS)

A large solar telescope is usually equipped with several post-focus instruments deployed to study the dynamics of the solar features at different wavelengths. Indian Institute of Astrophysics (IIA) has proposed to build a 2-m class National Large Solar Telescope (NLST) to be located at a site which is suitable for high resolution observations of the sun. The narrow band imager (NBI) is proposed to be one of the back-end instrument for NLST to provide a spectral resolution of 40 m Å or better. The NBI comprised of two Fabry-Perot interferometers kept in tandem. The instrument will be capable of observing the solar atmosphere at various wavelength positions of the spectral line with the expected temporal cadence of about one spectral image per second. The instrument will also have the additional capability of making Dopplergrams at very high cadence.The instrument can be combined with a high precision polarimeter to obtain the vector magnetic fields of the solar atmosphere (one or more levels) with good temporal cadence. Several simulations and numerical studies have been carried out to arrive at the optimal design of the instrument. In this paper, we present the important design parameters of the instrument such as wavelength coverage, optimum spacing ratio, parasitic light contribution, field-of-view, spectral and spatial resolution, signal-to-noise ratio etc. The theoretically estimated performance of the proposed NBI is also compared with similar instruments used around the world.

Ravindra, B.; Banyal, Ravinder Kumar

170

Barrett's esophageal adenocarcinoma diagnosed by narrow-band imaging magnifying endoscopy.  

PubMed

A 40-year-old man was referred to our hospital for detailed examination of a protuberant lesion in long-segment Barrett's esophagus (LSBE). Under white light endoscopy (WLE) the lesion appeared as a protuberant lesion with a rough surface and was diagnosed as 0-IIa-type tumor suspected to be a well-differentiated adenocarcinoma. A regular villous pattern was shown in the background mucosa of the LSBE by narrow-band imaging (NBI) magnifying endoscopy (NBI-ME). However, a slightly irregular villous pattern was observed on the lateral side of the main lesion. Therefore, a 0-IIa-type tumor was estimated to have a flatly lateral extension component (i.e. 0-IIb spreading). The 0-IIb spreading was unclear when using WLE, but could be diagnosed by NBI-ME based on the surface pattern differences. Markings were placed outside the edge of the flatly lateral extension, and endoscopic submucosal dissection was carried out.The pathological diagnosis of the protuberant lesion with flatly lateral spreading was well-differentiated adenocarcinoma. The macroscopic type was 0-IIa+IIb, 45 × 43 mm in size. The invasion depth was T1a (deep muscularis mucosae). Lymphatic and venous invasions were negative; horizontal and vertical margins were negative. In conclusion, NBI-ME was useful for the diagnosis of the flatly lateral extension of this 0-IIa+IIb esophageal adenocarcinoma in Barrett's esophagus. Further investigations with many cases are necessary. PMID:23617675

Takahashi, Akiko; Oyama, Tsuneo

2013-05-01

171

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

NASA Astrophysics Data System (ADS)

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.

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

2007-11-01

172

Stochastic jump and bifurcation of a slender cantilever beam carrying a lumped mass under narrow-band principal parametric excitation  

Microsoft Academic Search

A detailed theoretical investigation into the single-mode approximate response of a slender cantilever beam carrying a lumped mass subjected to base narrow-band random excitation is presented for the first time. The method of multiple scales is used and the stochastic jump and bifurcation have been investigated for the principal parametric resonance of the system using the stationary joint probability. Results

Z. H. Feng; X. D. Zhu; X. J. Lan

2011-01-01

173

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

SciTech Connect

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.

Allen, J. W.

2003-05-13

174

Simplified relationships for the probability distribution of the phase of a sine wave in narrow-band normal noise (Corresp.)  

Microsoft Academic Search

A new form of the probability distribution of the phase of a sine wave in narrow-band normal noise is derived. It leads to several different simple expressions for the probability distribution which render the previously required numerical integration of the probability density function unnecessary.

F. Weinstein; M. Zakai; J. Snyders; V. Mandrekar; M. Nadkarni

1974-01-01

175

Multicolor fluorescent semiconducting polymer dots with narrow emissions and high brightness.  

PubMed

Fluorescent semiconducting polymer dots (Pdots) have attracted great interest because of their superior characteristics as fluorescent probes, such as high fluorescence brightness, fast radiative rates, and excellent photostability. However, currently available Pdots generally exhibit broad emission spectra, which significantly limit their usefulness in many biological applications involving multiplex detections. Here, we describe the design and development of multicolor narrow emissive Pdots based on different boron dipyrromethene (BODIPY) units. BODIPY-containing semiconducting polymers emitting at multiple wavelengths were synthesized and used as precursors for preparing the Pdots, where intraparticle energy transfer led to highly bright, narrow emissions. The emission full width at half-maximum of the resulting Pdots varies from 40 to 55 nm, which is 1.5-2 times narrower than those of conventional semiconducting polymer dots. BODIPY 520 Pdots were about an order of magnitude brighter than commercial Qdot 525 under identical laser excitation conditions. Fluorescence imaging and flow cytometry experiments indicate that the narrow emissions from these bright Pdots are promising for multiplexed biological detections. PMID:23282278

Rong, Yu; Wu, Changfeng; Yu, Jiangbo; Zhang, Xuanjun; Ye, Fangmao; Zeigler, Maxwell; Gallina, Maria Elena; Wu, I-Che; Zhang, Yong; Chan, Yang-Hsiang; Sun, Wei; Uvdal, Kajsa; Chiu, Daniel T

2013-01-02

176

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

SciTech Connect

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.

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

177

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

NASA Astrophysics Data System (ADS)

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 (Eg = 2.85 eV) compared to the unmodified white Degussa TiO2 (Eg = 3.10 eV).

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

2013-06-01

178

Band-selective C- or L-band erbium-doped fiber amplified spontaneous emission source  

Microsoft Academic Search

Two novel methods are demonstrated to build up a band-selective amplified spontaneous emission (ASE) broadband light source that can operate in the selective conventional band (C-band, 1525~1565 nm) or long-wavelength band (L-band, 1565~1605 nm) region using a 1×2 optical switch. With the backward ASE feedback technique, an output power of 27.6 mW for the C-band ASE and 11.8 mW for

Xiulin Wang; Wencai Huang

2006-01-01

179

Physical Theory of Narrow-Band Sounds Associated with Intracranial Aneurysms  

NASA Astrophysics Data System (ADS)

Intracranial aneurysms in humans are sometimes associated with narrow-band sound. The sounds of interest have frequencies on the order of 500 Hz. Bandwidths observed correspond to quality factors on the order of 30. The present thesis offers a physical theory of the mechanism of excitation of these sounds. It is shown that an aneurysm can be modeled as a lumped-element resonator in which the kinetic energy is associated with the motion of blood in the neck of the aneurysm and the potential energy is stored in the flexible walls of the aneurysm sac. However, the quality factors of aneurysms as lumped-element resonators are seen to be much smaller than the observed quality factors of aneurysm sounds, so that aneurysm sounds cannot be explained as a simple resonance phenomenon associated with external forcing. It is shown that the best explanation for aneurysm sounds is a self-excited oscillation of the system comprised of the aneurysm and the unstable mean flow; this oscillation is explained quantitatively here for the first time. In the theory developed in this thesis, limit cycles of the aneurysm-flow system are found using describing -function analysis. Results of the theory agree quantitatively with experiments performed on flow-excited Helmholtz resonators and agree qualitatively with the observed characteristics of aneurysm sounds. The bandwidths of observed aneurysm sounds for a time-varying mean flow are predicted and compared with bandwidths of sounds due to periodic vortex shedding in the absence of any resonator. It is shown that the presence of a resonator causes a locking-in of the flow disturbances to the sounding frequency of the resonator, resulting in a narrow observed bandwidth, even for a time -varying mean flow. Bandwidth considerations make it possible to distinguish sounds associated with self-excited oscillations of aneurysms from sounds due to purely fluid-mechanical mechanisms. The theory presented here can be taken as a starting point for further research, including numerical, experimental and clinical study, with the goals of noninvasive acoustic diagnosis of aneurysms and characterization of aneurysmal tissue.

Mast, T. Douglas

180

Two Emission Bands of Cu+ Center in NaBr  

NASA Astrophysics Data System (ADS)

The second emission band (the ES band) which is observable only at low temperatures is found in NaBr:Cu+ at 4.11 eV (302 nm) through excitation at 5.06 eV (245 nm). The excitation spectrum at low temperatures shows a peak corresponding to the D2 absorption peak. The activation energies of thermal bleaching for the ES band and the known EL band are identified as 0.06 eV and 0.57 eV, respectively. The qualitative energy diagram for the emission process is shown.

Emura, Shuichi; Ishiguro, Masakazu

1988-08-01

181

Spectrophotometry: imaging with custom narrow-band filters and an automated data-reduction pipeline  

NASA Astrophysics Data System (ADS)

Abundance variations of carbon and nitrogen in globular star clusters provide astronomers with a means to determine a cluster's evolutionary past. Moreover, these clusters are so ancient (~13 billion years) and so well preserved that they provide an ideal diagnostic for the overall chemical history of the Milky Way Galaxy. Traditionally, spectroscopy is the preferred method to perform investigations into such theories. However, it is not without its drawbacks: spectroscopy can normally only be obtained star by star, and both large telescopes and a great deal of time is required to carry out research in this manner. As globular clusters are known to contain up to a million stars, studying each star individually would take too much time to return a true representative sample of the cluster stars. So, we opt instead for a spectrophotometric technique and a statistical approach to infer a cluster's composition variations. This has required the design and use of new custom narrow-band filters centered on the CH and CN molecular absorption bands or their adjacent continua. Two Galactic clusters (M71 & M92) with contrasting characteristics have been chosen for this study. In order to process this data a header-driven (i.e. automated) astronomical data-processing pipeline was developed for use with a family of CCD instruments known as the FOSCs. The advent of CCD detectors has allowed astronomers to generate large quantities of raw data on a nightly basis, but processing of this amount of data is extremely time and resource intensive. In our case the majority of our cluster data has been obtained using the BFOSC instrument on the 1.52m Cassini Telescope at Loiano, Italy. However, as there are a number of these FOSC instruments throughout the world, our pipeline can be easily adapted to suit any of them. The pipeline has been tested using various types of data ranging from brown dwarf stars to globular cluster images, with each new dataset providing us with new problems/bugs to solve and overcome. The pipeline performs various tasks such as data reduction including image de-fringing, image registration and photometry, with final products consisting of RGB colour images and colour magnitude diagrams (CMD).

Forde, Kieran P.; Butler, Raymond F.; Peat, David; Golden, Aaron; O'Tuairisg, Seathrun

2005-06-01

182

Reversal of Atopic Dermatitis with Narrow-Band UVB Phototherapy and Biomarkers for Therapeutic Response  

PubMed Central

Background Atopic dermatitis (AD) is a common inflammatory skin disease exhibiting a predominantly Th2/“T22” immune activation and a defective epidermal barrier. Narrow-band UVB (NB-UVB) is considered an efficient treatment for moderate-to-severe AD. In psoriasis, NB-UVB has been found to suppress the Th1/Th17-polarization with subsequent reversal of epidermal hyperplasia. The immunomodulatory effects of this treatment are largely unknown in AD. Objective To evaluate the effects of NB-UVB on immune and barrier abnormalities in AD, aiming to establish reversibility of disease and biomarkers of therapeutic response. Methods 12 moderate-to-severe chronic AD patients received NB-UVB phototherapy 3 times weekly for up to 12 weeks. Lesional and non-lesional skin biopsies were obtained before and after treatment and evaluated by gene-expression and immunohistochemistry studies. Results All patients had at least a 50% reduction in SCORing of AD (SCORAD) index with NB-UVB phototherapy. The Th2, “T22,” and Th1 immune pathways were suppressed and measures of epidermal hyperplasia and differentiation normalized. The reversal of disease activity was associated with elimination of inflammatory leukocytes, Th2/“T22”- associated cytokines and chemokines, and normalized expression of barrier proteins. Conclusions Our study shows that resolution of clinical disease in patients with chronic AD is accompanied by reversal of both the epidermal defects and the underlying immune activation. We have defined a set of biomarkers of disease response that associate resolved Th2 and “T22” inflammation in chronic AD patients with reversal of barrier pathology. By showing reversal of the AD epidermal phenotype with a broad immune-targeted therapy, our data argues against a fixed genetic phenotype.

Tintle, Suzanne; Shemer, Avner; Suarez-Farinas, Mayte; Fujita, Hideki; Gilleaudeau, Patricia; Sullivan-Whalen, Mary; Johnson-Huang, Leanne; Chiricozzi, Andrea; Cardinale, Irma; Duan, Shenghui; Bowcock, Anne; Krueger, James G.; Guttman-Yassky, Emma

2012-01-01

183

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

SciTech Connect

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.

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

184

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

PubMed

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

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

2012-10-30

185

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

186

Observation of ultra-narrow band plasmon induced transparency based on large-area hybrid plasmon-waveguide systems  

NASA Astrophysics Data System (ADS)

We report the observation of an ultra-narrow band plasmon induced transparency resonance which is realized in a large area hybrid plasmon-waveguide system consisting of a gold nanowire array embedded in a slab waveguide. Due to the destructive interference between optical modes supported by the hybrid system, an ultra-narrow plasmon induced transparency resonance with a bandwidth of 8 nm at the wavelength of 966 nm was obtained (i.e., ~1/120 of the peak wavelength at the incident angle of 60°). The group velocity is estimated to be ~76, which is promising for miniaturized slow-light components.

Zhang, Jing; Bai, Wenli; Cai, Likang; Xu, Yun; Song, Guofeng; Gan, Qiaoqiang

2011-10-01

187

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

NASA Astrophysics Data System (ADS)

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.

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

2005-04-01

188

Approximate first-passage and extremes of narrow-band Gaussian and non-Gaussian random vibrations  

Microsoft Academic Search

An approximate method for estimating the probability distribution of first-passage times and extreme values of stationary narrow-band random vibrations is presented. The advantage of the method is that explicit, closed from expressions are obtained. The method is applied to the response process of a simple linear oscillator driven by both Gaussian and non-Gaussian random excitations and, by comparison with published

A. Naess

1990-01-01

189

Measurement of electron lifetime, electron mobility and band-gap narrowing in heavily doped p-type silicon  

Microsoft Academic Search

The parameters that control the transport of minority carriers in heavily doped Si:B have been measured by a combination of steady state electrical and transient optical techniques. Electron diffusion length and electron lifetime measurements have been conducted on doped-as-grown wafers to extract the minority carrier electron mobility as a function of acceptor doping density. Effective band-gap narrowing in p+epitaxial layers

S. E. Swirhun; Y.-H. Kwark; R. M. Swanson

1986-01-01

190

Airborne Observations of the Infrared Emission Bands.  

National Technical Information Service (NTIS)

The data concerning low resolution airborne spectra from 5 to 8 microns available for a sample of 40 sources selected from the Infrared Astronomy Satellite low resolution spectral Atlas with polycyclic aromatic hydrocarbon (PAH) emission features, are dis...

M. Cohen J. Bregman F. C. Witteborn L. J. Allamandola D. H. Wooden

1989-01-01

191

The narrow pass band filter of tunable 1D phononic crystals with a dielectric elastomer layer  

Microsoft Academic Search

In this paper, we study the defect bands of a 1D phononic crystal consisting of aluminum (Al) and polymethyl methacrylate (PMMA) layers with a dielectric elastomer (DE) defect layer. The plane wave expansion (PWE) method and supercell calculation are used to calculate the band structure and the defect bands. The transmission spectra are obtained using the finite element method (FEM).

Liang-Yu Wu; Mei-Ling Wu; Lien-Wen Chen

2009-01-01

192

Spontaneous emission near the edge of a photonic band gap  

Microsoft Academic Search

We study spontaneous emission near the edge of a photonic band gap. Instead of a simple exponential decay in the vacuum, spontaneous emission displays an oscillatory behavior. A single photon-atom bound dressed state exhibits a fractional steady-state atomic population on the excited state. For a three-level atom we evaluate the spectral splitting and subnatural linewidth of spontaneous emission. In the

Sajeev John; Tran Quang

1994-01-01

193

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

PubMed Central

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

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

2012-01-01

194

Polarization-Control Components and Narrow-Band Filters Based on Subwavelength Grating Structures.  

NASA Astrophysics Data System (ADS)

Theoretical methods for modeling diffraction from grating structures are presented. These methods are used to investigate polarization properties and resonant effects of subwavelength-period grating structures. Applications discussed include a waveplate with high transmission, a partial polarization beamsplitter and a co-directional polarization beamsplitter used in magneto-optical data storage systems, and narrowband filters based on one-dimensional and two-dimensional gratings. Fabrication processes and measured results for the partial polarization beamsplitter and resonant grating filters are reported. The diffraction properties of subwavelength grating structures need to be analyzed through the use of rigorous electromagnetic theory. A computationally efficient implementation of rigorous coupled-wave analysis (RCWA) is presented. Specifically, the eigenvalue problem for a one-dimensional (1-D) grating in a conical mounting is reduced to two eigenvalue problems in the corresponding nonconical mounting. This reduction yields two n x n matrices to solve for eigenvalues and eigenvectors, where n is the number of orders retained in the computation. Computation on a two-dimensional (2 -D) grating is also simplified by reducing the size of the matrix in the eigenvalue problem to 2n x 2n. These simplifications reduce the computation time for the eigenvalue problem by 8 to 32 times compared to the original computation time. Phase retardation and diffraction efficiencies of zeroth-order dielectric gratings are modeled. The investigation emphasizes the transmission properties of these structures. It is found that if a zeroth-order dielectric grating is appropriately coated the transmissions for both orthogonal polarizations can be significantly enhanced. This result is particularly important for applications involving subwavelength grating structures in waveplates and birefringent computer-generated holograms. A co-directional polarization beamsplitter which consists of a subwavelength grating modulated by a coarse grating profile is also discussed. Subwavelength-period metallic gratings formed on transparent substrates are investigated. In particular, a partial polarization beamsplitter used in magneto-optical data storage systems is designed. Using aluminum grating structures, a device was fabricated through the use of holographic exposure and reactive ion etching; the measured results agreed with the theoretical predictions and met the basic system requirements. Detailed analysis of resonance phenomena in diffraction from two-dimensional (2D) gratings is presented. A polarization -independent narrowband reflection filter and a dual-linewidth reflection filter were designed. A 2D-grating structure consisting of a silicon nitride layer and a photoresist grating was fabricated. A symmetric, low-sideband resonant response that is suitable for narrow-band filter applications was achieved. One-dimensional-grating resonant filters, which consist of a silicon nitride waveguide layer and a silicon dioxide grating or a photoresist grating, were fabricated. Sub -nanometer linewidth and high efficiencies (>70%) were achieved.

Peng, Song

195

Absorption coefficient of luminescent bodies in the emission band  

NASA Astrophysics Data System (ADS)

Einstein's theory associating the coefficients of absorption, induced emission and spontaneous emission cannot be applied to luminescent systems, because the radiative transitions occur with the absorption or emission of phonons. It may be generalised to include luminescent systems by the use of a hollow sphere whose internal walls are covered with a substance irradiated by a Wood lamp, placed at the centre of the sphere. From this we determine the absorption coefficient of the luminescent substance in the emission band. Work performed in part at Groupe de Physique du Solide de l'Ecole Normale Superieure.

Alexic', A.; Nikoli?, K.; Buri?, J.; Magnant, D.; de La Garanderie, H. Payen

1982-02-01

196

SMOS REFLEX 2003: L-band emissivity characterization of vineyards  

Microsoft Academic Search

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,

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

197

Valence Band X-Ray Emission Spectra of Compressed Germanium  

SciTech Connect

We report measurements of the valence band width in compressed Ge determined from x-ray emission spectra below the Ge K edge. The width of the valence band does not show any pressure dependence in the semiconducting diamond-type structure of Ge below 10 GPa. On the other hand, in the metallic {beta}-Sn phase above 10 GPa the valence band width increases under compression. Density-functional calculations show an increasing valence band width under compression both in the semiconducting phase (contrary to experiment) and in the metallic {beta}-Sn phase of Ge (in agreement with observed pressure-induced broadening). The pressure-independent valence band width in the semiconducting phase of Ge appears to require theoretical advances beyond the density-functional theory or the GW approximation.

Struzhkin, Viktor V.; Mao Hokwang; Lin Jungfu; Hemley, Russell J. [Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC 20015 (United States); Tse, John S.; Ma Yanming [Steacie Institute for Molecular Science, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6 (Canada); Hu, Michael Y.; Chow, Paul [HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kao Chichang [NSLS, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2006-04-07

198

Wide and narrow band PD detection in plug-in cable connectors in the UHF range  

Microsoft Academic Search

Experience in on-line UHF partial discharge detection on high voltage plug-in cable connectors (terminations) for GIS and transformers are presented. Narrow vs. broadband, as well as zero-span measurements were carried out using a spectrum analyzer on a laboratory setup with a built-in artificial PD defect of variable intensity. A sensitivity below 5 pC turned out to be detectable by the

Denis Denissov; Wolfgang Köhler; Stefan Tenbohlen; Ruben Grund; Thomas Klein

2008-01-01

199

Coherent control of spontaneous emission near a photonic band edge  

Microsoft Academic Search

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

Mesfin Woldeyohannes; Sajeev John

2003-01-01

200

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

SciTech Connect

We experimentally demonstrate the production of narrow-band ({delta}f/f{approx_equal}20% at f{approx_equal}0.5THz) transition radiation with tunable frequency over [0.37, 0.86] THz. The radiation is produced as a train of sub-picosecond relativistic electron bunches transits at the vacuum-aluminum interface of an aluminum converter screen. The bunch train is generated via a transverse-to-longitudinal phase space exchange technique. We also show a possible application of modulated beams to extend the dynamical range of a popular bunch length diagnostic technique based on the spectral analysis of coherent radiation.

Piot, P.; Maxwell, T. J. [Northern Illinois Center for Accelerator and Detector Development and Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States); Accelerator Physics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Sun, Y.-E [Accelerator Physics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Ruan, J.; Lumpkin, A. H.; Thurman-Keup, R. [Accelerator Division, Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Rihaoui, M. M. [Northern Illinois Center for Accelerator and Detector Development and Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States)

2011-06-27

201

The Usefulness of Magnifying Endoscopy and Narrow-Band Imaging in Measuring the Depth of Invasion before Endoscopic Submucosal Dissection  

PubMed Central

With the widespread application of endoscopic submucosal dissection for the treatment of gastrointestinal neoplasms, accurate determination of the invasion depth prior to intervention has become an indispensable part of treatment planning. Narrow-band imaging (NBI) is a novel endoscopic technique that may enhance the accuracy of diagnosis. Magnifying endoscopy with NBI has been shown to be effective for determining invasion depth for intrapapillary capillary loop classification of esophageal cancer and microvascular pattern of stomach cancer. Such precise pre-treatment staging of early neoplastic lesions in the gastrointestinal tract warrants timely initiation of disease-tailored treatment and, ultimately, better quality of life and improved patient survival.

2012-01-01

202

Low-frequency ionospheric sounding with Narrow Bipolar Event lightning radio emissions: energy-reflectivity spectrum  

NASA Astrophysics Data System (ADS)

We analyze data on radio-reflection from the D-region of the lower ionosphere, retrieving the energy-reflection coefficient in the frequency range ~5 95 kHz. The data are the same as developed for a recent study of ionospheric-reflection height, and are based on recordings of powerful (multi-Gigawatt) radio emissions from a type of narrow (~10 ?s) lightning discharge known as "Narrow Bipolar Events". The sequential appearance of first the groundwave signal, and then the ionospheric single-hop reflection signal, permits us to construct the energy-reflection ratio. We infer the energy reflection's statistical variation with solar zenith angle, angle-of-incidence, frequency, and propagation azimuth. There is also a marginally-significant response of the energy reflectivity to solar X-ray flux density. Finally, we review the relationship of our results to previous published reports.

Jacobson, A. R.; Holzworth, R.; Shao, X.-M.

2008-06-01

203

The infrared emission bands. III. Southern IRAS sources.  

PubMed

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

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

1989-06-01

204

Narrow-band holographic optical filter using thick efficient holographic gratings  

NASA Astrophysics Data System (ADS)

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, (3) Large dynamic range for plane wave holograms, (4) Hard, freestanding, stable, polishable and coatable. We have written and characterized numerous gratings in 1.8 mm thick samples to study the effect of writing geometry on the spectral linewidth and field-of-view of a single grating in the reflection geometry. We have succeeded in writing some very efficient gratings at 15 degrees internal write angles with external slant angles of 5 degrees. These gratings exhibit linewidths of < 0.2 nm and diffraction efficiencies of better than 70 percent. The measured angular acceptance of these gratings ranges from 0.1 to 0.24 degrees. We have also written some initial angle multiplexed gratings which include 3 efficient gratings in the same volume in an attempt to increase the angular acceptance. In this manner we hope to achieve a highly efficient optical filter with extremely narrow spectral linewidth and wide angular acceptance. Filters based on thick volume holograms show great promise in Lidar applications and should result in superior S/N ratios.

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

2002-06-01

205

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

SciTech Connect

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

Schreibmann, Eduard [Department of Radiation Oncology, Stanford University School of Medicine Stanford, CA (United States); Xing Lei [Department of Radiation Oncology, Stanford University School of Medicine Stanford, CA (United States)]. E-mail: lei@reyes.stanford.edu

2005-06-01

206

Narrow-band MMIC filters with automatic tuning and Q-factor control  

Microsoft Academic Search

Fully integrated, narrowband, tunable active filter monolithic microwave integrated circuits (MMICs) have been demonstrated at X-band. The three-section bandpass chip had a minimum insertion loss of less than 1.5 dB and a -3 dB bandwidth of 3% at 8.4 GHz. The notch filter chip exhibited a minimum -30 dB notch bandwidth of 20 MHz and a 2.7-GHz tuning range. A

P. Katzin; B. Bedard; Y. Ayasli

1993-01-01

207

A manganese-doped polymeric framework of polyoxotitanate nanoclusters with a narrow band gap.  

PubMed

A three-dimensional coordination polymer based on a manganese-doped polyoxotitanate nanocluster, {Ti13Mn4O16[MeC(CH2O)3]4(OEt)12Br4}?, has been synthesized under solvothermal conditions. It is the first framework of doped polyoxotitanate nanoclusters reported in the literature. Compared with anatase, its band gap is reduced from 3.19 to 2.57 eV. PMID:24042234

Chen, Yang; Sokolow, Jesse D; Trzop, Elzbieta; Coppens, Philip

2013-10-15

208

A tunable fiber laser for the 2?m wavelength range based on narrow band optical parametric amplification and an intra-cavity thulium doped fiber active filter  

Microsoft Academic Search

Fiber parametric amplification (FPA) [1] is an efficient mechanism for achieving tunable light sources in wavelength ranges that cannot be accessed by other means. Two FPA regimes are possible: broad band gain takes place when the pump experiences anomalous dispersion (?2 < 0) [2], and narrow band gain for a pump propagating in the normal dispersion regime (?2 > 0)

A. Gershikov; J. Lasri; Z. Sacks; G. Eisenstein

2011-01-01

209

Simulation of radiated narrow band electromagnetic interference for components in the automotive industry (bulk current injection)  

Microsoft Academic Search

Electro-smog is a term which stands for all kind of electromagnetic fields which are around the world, such as RF (radio frequency) field from radio and TV stations, radiation from high voltage transmission lines, mobile communication and high frequency emission from household equipment. In this paper, we will analyze the influence of such radiated fields on products used in the

H. Kunkel; S. Klezar

2003-01-01

210

Assessment of some mechanisms for near IR narrow pass-band filters  

Microsoft Academic Search

Two types of novel physical systems are examined as possible IR filters. To observe a small, hot CO2 source against a cooler but strong background of CO2 emission, the background must be exceedingly uniform. An optically thick filter of CO2 can turn a variable background into a uniform one, while still transmitting the hot signal at high rotational lines. At

J. W. Chamberlain; M. A. Ruderman

1977-01-01

211

[FeII] Narrow Band Imaging of Supernova Remnants in the Magellanic Clouds  

NASA Astrophysics Data System (ADS)

Optical, radio and X-ray emission from supernova remnants (SNRs) has been used extensively to study the properties of SNRs, and as such, much is known about their general characteristics in these wavebands. However, surprisingly little work has been done in the near infrared. The early work of Oliva et al. (1989, A&A, 214, 307) suggested that SNRs are generally bright in the emission of [FeII], although this conclusion was based upon observations of only a few very bright SNRs. In order to better define the general characteristics of the [FeII] emission of SNRs, we have undertaken a survey of 35 SNRs in the Magellanic Clouds. These represent a well defined sample with a large range of intrinsic properties, all at the same distance. We present [FeII] fluxes of 1.64mu m emission and discuss correlations of SNR properties observed at other wavelengths with the [FeII] flux. In addition, we discuss the feasibility of using [FeII] flux as an indicator of supernova rates in distant galaxies.

Tavarez, M.; Smith, R. C.; Elston, R.

1996-12-01

212

Narrow Band Gaps of In-rich Group III-Nitrides  

Microsoft Academic Search

It has been commonly accepted that all group III-nitrides are wide gap semiconductors with the band gaps covering the energy range from 1.9 eV in InN to 6.2 eV in AlN. Although Ga-rich Ga_xIn_1-xN alloys have been extensively studied and are used in commercial products much less has been known about the In-rich side of this alloy system. I will

Wladek Walukiewicz

2003-01-01

213

Narrow-band X-ray photometry as a tool for studying galaxy and cluster mass distributions  

NASA Astrophysics Data System (ADS)

We explore the utility of narrow-band X-ray surface photometry as a tool for making fully Bayesian, hydrostatic mass measurements of clusters of galaxies, groups and early-type galaxies. We demonstrate that it is sufficient to measure the surface photometry with the Chandra X-ray Observatory in only three (rest frame) bands (0.5-0.9, 0.9-2.0 and 2.0-7.0 keV) in order to constrain the temperature, density and abundance of the hot interstellar medium (ISM). Adopting parametrized models for the mass distribution and radial entropy profile and assuming spherical symmetry, we show that the constraints on the mass and thermodynamic properties of the ISM that are obtained by fitting data from all three bands simultaneously are comparable to those obtained by fitting similar models to the temperature and density profiles derived from spatially resolved spectroscopy, as is typically done. We demonstrate that the constraints can be significantly tightened when exploiting a recently derived, empirical relationship between the gas fraction and the entropy profile at large scales, eliminating arbitrary extrapolations at large radii. This `Scaled Adiabatic Model' is well suited to modest signal-to-noise ratio data, and we show that accurate, precise measurements of the global system properties are inferred when employing it to fit data from even very shallow, snapshot X-ray observations. The well-defined asymptotic behaviour of the model also makes it ideally suited for use in Sunyaev-Zeldovich studies of galaxy clusters.

Humphrey, Philip J.; Buote, David A.

2013-10-01

214

A six-pole narrow-band high temperature superconducting filter with wide stop-band response at P-band  

NASA Astrophysics Data System (ADS)

A quarter-wavelength stepped impedance resonator (QWSIR) is proposed for high temperature superconducting (HTS) filter, offering wide stop-band performance. A six-pole P-band HTS filter with QWSIRs was designed and fabricated. The filter has a fractional bandwidth of 0.8% at 516 MHz and shows the lowest spurious frequency at about 2.15 GHz. The measured results of the HTS filter are in good agreement with simulations.

Gong, Liming; Wei, Bin; Zhang, Ying; Zhang, Xiaoping; Guo, Xubo; Zhang, Guoyong; Cao, Bisong

2013-10-01

215

Research and design of an optical system of biochemical analyzer based on the narrow-band pass filter  

NASA Astrophysics Data System (ADS)

Biochemical analyzer is one of the important instruments in the clinical diagnosis, and its optical system is the important component. The operation of this optical system can be regard as three parts. The first is transforms the duplicate colored light as the monochromatic light. The second is transforms the light signal of the monochromatic, which have the information of the measured sample, as the electric signal by use the photoelectric detector. And the last is to send the signal to data processing system by use the control system. Generally, there are three types monochromators: prism, optical grating and narrow-band pass filter. Thereinto, the narrow-band pass filter were widely used in the semi-auto biochemical analyzer. Through analysed the principle of biochemical analyzer base on the narrow-band pass filter, we known that the optical has three features. The first is the optical path of the optical system is a non- imaging system. The second, this system is wide spectrum region that contain visible light and ultraviolet spectrum. The third, this is a little aperture and little field monochromatic light system. Therefore, design idea of this optical system is: (1) luminous energy in the system less transmission loss; (2) detector coupled to the luminous energy efficient; mainly correct spherical aberration. Practice showed the point of Image quality evaluation: (1) dispersion circle diameter equal the receiving device pixel effective width of 125%, and the energy distribution should point target of 80% of energy into the receiving device pixel width of the effective diameter in this dispersion circle; (2) With MTF evaluation, the requirements in 20lp/ mm spatial frequency, the MTF values should not be lower than 0.6. The optical system should be fit in with ultraviolet and visible light width spectrum, and the detector image plane can but suited the majority visible light spectrum when by defocus optimization, and the image plane of violet and ultraviolet excursion quite large. Traditional biochemical analyzer optical design not fully consider this point, the authors introduce a effective image plane compensation measure innovatively, it greatly increased the reception efficiency of the violet and ultraviolet.

Xiao, Ze-xin; Chen, Kuan

2008-03-01

216

Emission from CO band heads in young stellar objects  

NASA Astrophysics Data System (ADS)

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.

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

1987-01-01

217

An analysis of the information dependence between MODIS emissive bands  

NASA Astrophysics Data System (ADS)

Multispectral, hyperspectral and ultraspectral imagers and sounders are increasingly important for atmospheric science and weather forecasting. The recent advent of multipsectral and hyperspectral sensors measuring radiances in the emissive IR are providing valuable new information. This is due to the presence of spectral channels (in some cases micro-channels) which are carefully positioned in and out of absorption lines of CO2, ozone, and water vapor. These spectral bands are used for measuring surface/cloud temperature, atmospheric temperature, Cirrus clouds water vapor, cloud properties/ozone, and cloud top altidude etc. The complexity of the spectral structure wherein the emissive bands have been selected presents challenges for lossless data compression; these are qualitatively different than the challenges offered by the reflective bands. For a hyperspectral sounder such as AIRS, the large number of channels is the principal contributor to data size. We have shown that methods combining clustering and linear models in the spectral channels can be effective for lossless data compression. However, when the number of emissive channels is relatively small compared to the spatial resolution, such as with the 17 emissive channels of MODIS, such techniques are not effective. In previous work the CCNY-NOAA compression group has reported an algorithm which addresses this case by sequential prediction of the spatial image. While that algorithm demonstrated an improved compression ratio over pure JPEG2000 compression, it underperformed optimal compression ratios estimated from entropy. In order to effectively exploit the redundant information in a progressive prediction scheme we must, determine a sequence of bands in which each band has sufficient mutual information with the next band, so that it predicts it well. We will provide a covariance and mutual information based analysis of the pairwise dependence between the bands and compare this with the qualitative expected dependence suggested by a physical analysis. This compression research is managed by Roger Heymann, PE of OSD NOAA NESDIS Engineering, in collaboration with the NOAA NESDIS STAR Research Office through Mitch Goldberg, Tim Schmit, Walter Wolf.

Gottipati, Srikanth; Gladkova, Irina; Grossberg, Michael

2008-08-01

218

Thermoluminescence of the green emission band of calcite  

NASA Astrophysics Data System (ADS)

The thermoluminescence (TL) characteristics of the green emission band of natural calcite are studied. The kinetic parameters of the natural and laboratory-induced defects were estimated. The ?-dose response was studied in the range of 0.01-104 Gy. The fading rate at room temperature is monitored over a period of 30 days. The results showed that calcite has a potential use as a material for ?-ray TL dosimeters for food sterilization, testing of materials and other industrial or reactor procedures.

Soliman, C.; Metwally, Saleh M.

219

On the Negative Delay Time of a Narrow-Band Signal as It Passes Through the Resonant Filter of Absorption  

NASA Astrophysics Data System (ADS)

It is shown that a narrow-band signal with smoothly varying envelope can have a negative delay time upon filtering by certain physically realizable filters, i.e., the smooth-signal envelope shifts forward rather than backward. We show that this does not contradict the casuality principle, since the advanced appearance of the signal has the nature of prediction of the future signal level from the time dependence of its level in the past. It is shown that in the case of a negative delay time, the time dependence of a switched-off signal can be recovered, i.e., reception of the untransmitted part of the signal is possible. We propose to use these phenomena for predicting signals of natural and artificial origin.

Bukhman, N. S.; Bukhman, S. V.

2004-01-01

220

Atomic vapor filter for two-dimensional Rayleigh imaging experiments with a narrow-band KrF excimer laser  

NASA Astrophysics Data System (ADS)

An optical transition of atomic iron can be used to build a two-dimensional absorption filter that operates in the tuning range of a narrow-band KrF excimer laser (0.05-cm 1 bandwidth). Iron atoms with a number density of 2 10 13 cm 3 are produced by thermal dissociation of iron pentacarbonyl Fe(CO) 5 . With this filter it is possible to discriminate Mie and surface-scattered light against Rayleigh scattering. For Rayleigh scattering from the exhaust gas of a methane air flame at a measured temperature of 1970 K, the ratio of transmission for Rayleigh scattering to transmission for Mie scattering is 16.8. Single-shot scattering from the exhaust gas of a high-pressure burner is presented as an application.

Gölz, P.; Andresen, P.

1996-10-01

221

Efficient narrow-band direct modulation of semiconductor injection lasers at millimeter wave frequencies of 100 GHz and beyond  

SciTech Connect

It has been demonstrated both theoretically and experimentally that it is possible to mode lock semiconductor lasers at millimeter wave frequencies approaching and beyond 100 GHz. The mode-locked output usually takes the form of sinusoidal modulation, and can be regarded for practical purposes as a highly efficient means of directly modulating an optical carrier in a narrow band at millimeter wave frequencies. In active mode locking, the external signal efficiently creates the optical modulation, while in passive mode locking a small external signal imposes its information on the optical carrier by injection locking the passive mode-locked output. Experimentally, we have demonstrated passive mode locking at 70 GHz using a tandem contact GaAs laser.

Lau, K.Y.

1988-06-27

222

New vibrational bands in nitrogen laser emission spectra  

NASA Astrophysics Data System (ADS)

Nitrogen laser emission spectra was analyzed using a 0.5-m Jarrell-Ash monochromator. In addition to the (0,0) 337.1-nm band, the laser spectra were found to contain (0,1) 357.69-nm, (2,4) 371.05-nm, (1,0) 315.93-nm, (0,2) 380.49-nm, (0,3) 405.94-nm, (1,3) 375.54-nm, (1,4) 399.84-nm, and (1,2) 353.67-nm bands belonging to the second positive system of the N2 molecule. A new transition from one of the mixed vibrational levels of C and C' states of the N2 molecule was observed in the laser spectra at 331.83 nm with a relative intensity of about 29 percent. Two bands, at 340.85 and 303.49 nm, belonging to the beta system of the NO molecule were also observed. The intensity variation of the prominent bands observed was studied with respect to change in operating pressure and voltage for deriving the optimum conditions for emission at these wavelengths.

Subhash, N.; Kartha, S. C.; Sathianandan, K.

1983-11-01

223

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

224

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

NASA Astrophysics Data System (ADS)

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.

Dunlop, David J.; Özdemir, Özden

2001-10-01

225

Narrow-band high-power semiconductor lasers for optical communication  

NASA Astrophysics Data System (ADS)

We present a compact Extended Cavity Laser (ECL) system based on a high-power laser diode optimized for maximum efficiency of the Rb optical pumping process. The system represents the crucial part of the HpG (hyperpolarized gasses) production process. We concentrated on the ECL system optimization - linewidth matching and frequency stabilization - for the optical pumping process. We show that the intensity of optical feedback in the ECL laser influences linewidth and output power and it is possible to find an optimum value for the highest power spectral density at the absorption line of desire. The emission linewidth was reduced approximately 10 times with only half of the total optical power loss. The ECL system is controlled by electronic servo-loop for laser frequency stabilization.

Buchta, Zden?k; ?íp, Ond?ej; Wilfert, Otakar; Lazar, Josef

2007-09-01

226

Production of intense, coherent, tunable narrow-band lyman-alpha radiation  

SciTech Connect

Nearly transform limited pulses of 1216 A radiation have been generated by sum frequency generation in 0.1 to 10 torr of mercury vapor. The summed input beams, consisting of photons at 3127 A and 5454 A originate in 1 MHz band-width ring-dye laser oscillators. The beams are amplified in pulsed-dye amplifiers pumped by the frequency doubled output of a Nd:YAG laser. The 3127 A photons are tuned to be resonant with the two-photon 6{sup 1}S to 7{sup 1}S mercury transition. The VUV radiation can be tuned by varying the frequency of the third non-resonant photon. We have also observed difference frequency generation at 2193 A and intense fluorescence from the 6{sup 1}P state at 1849 A. We have studied the intensity and linewidth dependence of the 1849 A fluorescence and 1216 A sum frequency signals on input beam intensity, mercury density, and buffer gas pressure and composition.

Turley, R.S.; McFarlane, R.A. (Hughes Research Laboratories, Malibu, CA 90265 (US)); Steel, D.G.; Remillard, J. (University of Michigan, Ann Arbor, MI 48109)

1988-10-01

227

Beyond the Limb: A Narrow Band EUV Search for Background Objects with the AIA  

NASA Astrophysics Data System (ADS)

As the star closest to Earth, the Sun provides us with the opportunity to study up close and test models for X-ray stellar activity. Its close proximity (and consequent brightness), however, makes it challenging to observe the Sun and other celestial objects with the same instrument; thus instrumental cross-calibration difficulties have complicated comparison of the Sun with other stars. The new Solar Dynamics Observatory (SDO) launched in February 2010 may at last allow for direct comparison of the Sun and other stars. The Atmospheric Imaging Assembly (AIA) onboard the SDO, a series of telescopes taking images of the full Sun at high spatial and temporal resolution in seven extreme ultraviolet (EUV) pass bands, can potentially observe background objects passing within the field of view of the telescopes off the limb of the Sun. Young stars, active galactic nuclei and other strong X-ray and EUV emitters may be bright enough to observe after careful background subtraction. Using technical specifications of the telescopes and measured X-ray fluxes of various background sources, we determined that with exposure times of the order of minutes, significantly longer than the standard 3s exposure, we should be able to observe the brightest background sources when they pass in the AIA field of view. We also determined what kinds of instrumental limitations we need to overcome and how best to make observations of these dim background sources.

Schonfeld, Sam; Testa, P.; Saar, S.

2011-01-01

228

Beyond the Limb: A Narrow Band EUV search for Background Objects with the AIA  

NASA Astrophysics Data System (ADS)

As the star closest to Earth, the Sun provides us with the opportunity to study up close and test models for X-ray stellar activity. Its close proximity (and consequent brightness), however, makes it challenging to observe the Sun and other celestial objects with the same instrument; thus instrumental cross-calibration difficulties have complicated comparison of the Sun with other stars. The new Solar Dynamics Observatory (SDO) launched in February 2010 may at last allow for direct comparison of the Sun and other stars. The Atmospheric Imaging Assembly (AIA) onboard the SDO, a series of telescopes taking images of the full Sun at high spatial and temporal resolution in seven extreme ultraviolet (EUV) pass bands, can potentially observe background objects passing within the field of view of the telescopes off the limb of the Sun. Young stars and other strong X-ray and EUV emitters may be bright enough to observe after careful background subtraction. Using technical specifications of the telescopes and measured X-ray fluxes of various background sources, we determined that with exposure times of the order of minutes, significantly longer than the standard ˜3s exposure, we should be able to observe the brightest background sources when they pass in the AIA field of view. We also began determining what kinds of instrumental limitations we need to overcome and how best to make observations of these dim background sources.

Schonfeld, Sam

2010-10-01

229

Characterization and application of a narrow band Lyman-alpha light source  

NASA Astrophysics Data System (ADS)

The Lyman-alpha emission line shape of dissociated hydrogen atoms in a high pressure Ne environment is studied. Vacuum ultra-violet absorption spectroscopy using the emitted Lyman-alpha radiation allows for the measurement of trace concentrations of ground state deuterium atoms in a hydrogen environment. Near resonant energy transfer from Ne excimer molecules to dissociative excitation of hydrogen molecules is utilized to generate excited state, n = 2, hydrogen atoms. Plasmas are generated in systems containing 250 to 600 [Torr] Ne with an admixture of 0.10 [Torr] H2 using a 12 [keV] electron beam. Experimental data on the upper states of the Lyman-alpha transition is collected via a new application of the dc opto-galvanic effect in low temperature, high pressure plasmas. A model line shape containing a non-thermal equilibrium atomic velocity distribution and pressure effects is developed. Excess energy from second continuum Ne excimers is imparted primarily to the dissociated hydrogen atoms giving the excited atoms a large excess velocity component. The dominant pressure effect is van der Waals interactions between the excited hydrogen atoms and ground state Ne atoms. Adjustable model parameters are optimized to fit the experimental data. Pressure broadening is observed to be non-linear, with the largest deviations from the predicted widths occurring at the lowest Ne pressures, while pressure shifting is linear in Ne pressure. The higher pressure data approaches the theoretical ratio between pressure width and shift for van der Waals interactions. Smooth extrapolation of the fit parameters, toward the theoretical limit, allows for the calculation of a Lyman-alpha emission line shape at a Ne pressure of 760 [Torr]. Hydrogen is replaced with deuterium in the system to provide a light source for absorption spectroscopy of ground state deuterium atoms. A discharge tube is filled to 3.5 [Torr] with H2 after introduction of a small admixture of D2. A discharge is ignited and absorption of the deuterium Lyman-alpha radiation is measured at various D2 partial pressures. The system clearly demonstrates sensitivity to variation in the D2 partial pressure in a constant pressure H2 environment. Projected sensitivity for this simple, inexpensive measurement system is approximately 180 delta around mural abundance.

McCarthy, Timothy J.

230

Identification of stimulus cues in narrow-band tone-in-noise detection using sparse observer models.  

PubMed

The classical psychophysical paradigm of narrow-band tone-in-noise (TiN) detection has been under investigation for more than 70?years, yet no conclusive answer has been given as to which auditory stimulus features listeners rely on. Here, individual observer models were fit to a large trial-by-trial behavioral data set using a modern statistical analysis procedure. Relative perceptual weights were estimated for a set of auditory features including sound energy, representations of the spectra as well as summary statistics of both fine structure and envelope. The fitted models captured the behavior of all listeners on a single-trial level. The estimated perceptual weights were stable across signal levels. They suggest that responses of observers depended on stimulus energy, though that cue was not always dominant, as well as on band-pass detectors applied to the fine structure spectrum. A subset of the observers exhibited an additional dependence on sound envelope which was best captured by two envelope descriptors: average slope and extrema count. For some listeners, a concurrent analysis of sequential dependencies showed interactions between the current and several preceding decisions. There was no unique answer regarding the strategy individual listeners employ during TiN detection, and implications thereof are discussed. PMID:23862820

Schönfelder, Vinzenz H; Wichmann, Felix A

2013-07-01

231

Characterization of a Narrow Band Lyman-alpha (121nm) Radiation Source  

NASA Astrophysics Data System (ADS)

Efficient near resonant energy transfer from Ne2 excimer molecules to dissociate H2 to H (n=1) and H (n=2) has been demonstrated using 12 kV electrons.^1 In order to efficiently form excimer molecules a Ne pressure of > 250 Torr is required. The nature of the energy transfer from the second continuum Ne excimers produces excited H atoms which are not in thermal equilibrium with the atomic Ne bath. The combination of relatively high pressure and non-thermal velocity distribution yields a complex emission profile. A novel use of the DC opto-galvonic (OG) effect in conjunction with a tunable laser diode has allowed a measurement of the Balmer-? (656nm) line shape in the radiation source. The laser is tuned through the fine structure of the Balmer-? transition, and a low pressure hydrogen containing RF discharge OG signal, providing an absolute frequency calibration, is simultaneously measured with the DC OG signal from the source. A model was developed to predict the velocity distribution of the radiating H atoms. This distribution was then convoluted with a pressure broadened and shifted Lorentzian line shape to yield the best fit to the data over a range of source pressures. A thorough understanding of the velocity distribution of the H (n=2) atoms allows for an accurate prediction of the emitted 121nm line profile. ^1 J. Wieser, et al, Journal of Physics B, 31, 4589-97 (1998)

McCarthy, T.; Murnick, D. E.; Salvermoser, M.; Ulrich, A.

2003-04-01

232

Narrow-band long-/very-long wavelength two-color type-II InAs/GaSb superlattice photodetector by changing the bias polarity  

NASA Astrophysics Data System (ADS)

We report on a narrow-band two-color photodetector using type-II InAs/GaSb superlattices (SLs) in the long-/very-long wavelength infrared (VLWIR) ranges by changing the polarity of the bias. The narrow-band photoresponse is achieved by sequentially growing the doped SL structure that has a shorter cutoff wavelength as a low-pass filter for the absorption layers that has a longer cutoff wavelength. At 77 K, the 50% cutoff wavelength of the photodiode is 10 ?m when the applied bias voltage is -0.1 V and is 16 ?m at +40 mV. The ??/? is 44% for the LWIR band and is 46% for the VLWIR band.

Zhang, Yanhua; Ma, Wenquan; Wei, Yang; Cao, Yulian; Huang, Jianliang; Cui, Kai; Guo, Xiaolu

2012-04-01

233

On the robustness of TC-DTR UWB receivers to narrow-band interference: Performance analysis and guidelines for system optimization  

Microsoft Academic Search

In this paper, we analyze the performance of a particular class of Transmitted-Reference (TR) receiver for Impulse Radio (IR) Ultra Wide Band (UWB) communication systems, which is called Chip-Time Differential Transmitted- Reference (TC-DTR). The analysis aims at investigating the performance of this receiver in the presence of faded narrow- band interference, and at comparing it with other TR receiver schemes

Marco Di Renzo; Dario De Leonardis; Fabio Graziosi; Fortunato Santucci

2009-01-01

234

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

PubMed Central

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.

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

2013-01-01

235

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

SciTech Connect

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.

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

236

Endoscopic Detection of Early Esophageal Squamous Cell Carcinoma in Patients with Achalasia: Narrow-Band Imaging versus Lugol's Staining  

PubMed Central

Chromoendoscopy with Lugol's staining remains the gold standard technique for detecting superficial SCC. An alternative technique, such as narrow-band imaging (NBI), for “optical staining” would be desirable, since NBI is a simpler technique and has no known complications. In this study, we compare NBI without magnification and chromoendoscopy with Lugol's staining for detecting high-grade dysplasia and intramucosal esophageal squamous cell carcinoma (SCC) in patients with achalasia. This was a prospective observational study of 43 patients with achalasia referred to the Gastrointestinal Endoscopy Unit of the Hospital of Clinics, São Paulo, University Medical School, Brazil, from October 2006 to February 2007. Conventional examinations with white light, NBI, and Lugol staining were consecutively performed, and the suspected lesions were mapped, recorded, and sent for biopsy. The results of the three methods were compared regarding sensitivity, specificity, accuracy, positive predictive value, negative predictive value, positive likelihood value, and negative likelihood value. Of the 43 patients, one was diagnosed with esophageal squamous cell carcinoma, and it was detected by all of the methods. NBI technology without magnification has high sensitivity and negative predictive value for detecting superficial esophageal squamous cell carcinoma, and it has comparable results with those obtained with Lugol's staining.

Ide, Edson; Carneiro, Fred Olavo Aragao Andrade; Frazao, Mariana Souza Varella; Chaves, Dalton Marques; Sallum, Rubens Antonio Aissar; de Moura, Eduardo Guimaraes Hourneaux; Sakai, Paulo; Cecconello, Ivan; Maluf-Filho, Fauze

2013-01-01

237

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

SciTech Connect

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

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

2009-06-07

238

Continuous narrow-band amplification tuning effect at terahertz frequencies in double-quantum-well resonant tunneling nanostructures  

NASA Astrophysics Data System (ADS)

High-frequency response properties of single and double-quantum-well resonant tunneling diodes (RTD) are examined in a wide frequency range, up to terahertz (THz) frequencies, on the base of proposed quantum theory. Numerical solutions of time-dependent Schrödinger equations with open-system boundary conditions in an external electromagnetic field are performed. The numerical solutions take into account the influence of bias DC voltage on electronic states in RTD with finite height and width of barriers both for monoenergetic and for Fermi-distributed electrons in emitter and collector parts of structures. We show that the presence of an additional level in double-quantum-well structures breaks the response symmetry and leads to selective narrow-band frequency amplification, as well as to the effect of amplification frequency tuning at THz frequencies by variation of applied bias voltage. These phenomena predict an increase of gain coefficient and open new perspectives for engineering of novel types of THz oscillators and other high-frequency units.

Kapaev, Vladimir V.; Murzin, Vladimir N.; Savinov, Sergey A.

2013-01-01

239

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

PubMed

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

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

2013-02-12

240

Narrow Band Imaging with Magnification Endoscopy for Celiac Disease: Results from a Prospective, Single-Center Study  

PubMed Central

In celiac disease (CD), the intestinal lesions can be patchy and partial villous atrophy may elude detection at standard endoscopy (SE). Narrow Band Imaging (NBI) system in combination with a magnifying endoscope (ME) is a simple tool able to obtain targeted biopsy specimens. The aim of the study was to assess the correlation between NBI-ME and histology in CD diagnosis and to compare diagnostic accuracy between NBI-ME and SE in detecting villous abnormalities in CD. Forty-four consecutive patients with suspected CD undergoing upper gastrointestinal endoscopy have been prospectively evaluated. Utilizing both SE and NBI-ME, observed surface patterns were compared with histological results obtained from biopsy specimens using the k-Cohen agreement coefficient. NBI-ME identified partial villous atrophy in 12 patients in whom SE was normal, with sensitivity, specificity, and accuracy of 100%, 92.6%, and 95%, respectively. The overall agreement between NBI-ME and histology was significantly higher when compared with SE and histology (kappa score: 0.90 versus 0.46; P = 0.001) in diagnosing CD. NBI-ME could help identify partial mucosal atrophy in the routine endoscopic practice, potentially reducing the need for blind biopsies. NBI-ME was superior to SE and can reliably predict in vivo the villous changes of CD.

De Luca, L.; Ricciardiello, L.; Rocchi, M. B. L.; Fabi, M. T.; Bianchi, M. L.; de Leone, A.; Fiori, S.; Baroncini, D.

2013-01-01

241

Narrow band imaging with magnification endoscopy for celiac disease: results from a prospective, single-center study.  

PubMed

In celiac disease (CD), the intestinal lesions can be patchy and partial villous atrophy may elude detection at standard endoscopy (SE). Narrow Band Imaging (NBI) system in combination with a magnifying endoscope (ME) is a simple tool able to obtain targeted biopsy specimens. The aim of the study was to assess the correlation between NBI-ME and histology in CD diagnosis and to compare diagnostic accuracy between NBI-ME and SE in detecting villous abnormalities in CD. Forty-four consecutive patients with suspected CD undergoing upper gastrointestinal endoscopy have been prospectively evaluated. Utilizing both SE and NBI-ME, observed surface patterns were compared with histological results obtained from biopsy specimens using the k-Cohen agreement coefficient. NBI-ME identified partial villous atrophy in 12 patients in whom SE was normal, with sensitivity, specificity, and accuracy of 100%, 92.6%, and 95%, respectively. The overall agreement between NBI-ME and histology was significantly higher when compared with SE and histology (kappa score: 0.90 versus 0.46; P = 0.001) in diagnosing CD. NBI-ME could help identify partial mucosal atrophy in the routine endoscopic practice, potentially reducing the need for blind biopsies. NBI-ME was superior to SE and can reliably predict in vivo the villous changes of CD. PMID:23983448

De Luca, L; Ricciardiello, L; Rocchi, M B L; Fabi, M T; Bianchi, M L; de Leone, A; Fiori, S; Baroncini, D

2013-08-06

242

Magnifying endoscopy with narrow-band imaging findings in the diagnosis of Barrett's esophageal adenocarcinoma spreading below squamous epithelium.  

PubMed

It has been described that most cases of Barrett's esophageal adenocarcinoma in Japan are cases of Barrett's esophageal adenocarcinoma on a background of short-segment Barrett's esophagus, frequently occurring rostrad to Barrett's epithelium, adjacent to the squamous epithelium of the right wall of the esophagogastric junction. Barrett's esophageal adenocarcinoma may spread below the squamous epithelium when the tumor is situated adjacent to the squamocolumnar junction, so that it is usually difficult to diagnose its presence and extent by conventional endoscopy alone. We have noted that the spread of Barrett's esophageal adenocarcinoma below the squamous epithelium is recognizable as annular vascular formations (AVF) by magnifying endoscopy with narrow-band imaging (ME-NBI), and have verified it by 3-D stereo-reconstruction using serial sections from a specimen of the same lesion. When horizontal cross-sections of the tissue were viewed from the surface, AVF emerged at a depth of approximately 100 ?m from the surface and disappeared at a depth of approximately 300 ?m. Therefore, it would be presumed to be difficult to visualize the characteristic structural features by ME-NBI if the carcinomatous glandular ducts were situated deeper than approximately 300 ?m underneath a thick layer of squamous epithelium. Thickness of the overlying squamous epithelium may be a limiting factor for whether or not the characteristic structural features can be detected. PMID:23617670

Omae, Masami; Fujisaki, Junko; Shimizu, Tomoki; Igarashi, Masahiro; Yamamoto, Noriko

2013-05-01

243

Usefulness of magnifying endoscopy with narrow-band imaging for determining tumor invasion depth in early gastric cancer.  

PubMed

Backgrounds. Magnifying endoscopy with narrow-band imaging (ME-NBI) has become essential for determining tumor margin in early gastric cancer (EGC). Here, we investigated the usefulness of ME-NBI for assessment of invasion depth in EGC. Methods. For 119 patients who had undergone ME-NBI and en bloc resection by endoscopic submucosal dissection, three physicians prospectively examined high-magnification ME-NBI images for clinical features such as presence or absence of dilated vessels (D vessels). Cases with D vessels verified by at least two physicians were assigned to group V, and others were assigned to group N. We then compared clinicopathological factors associated with the groups. Results. Groups V and N consisted of 18 and 101 patients, respectively. There were no significant differences in age, gender, tumor size, tumor location, gross morphology, or histological type. The percentage of submucosal cancer was 9.9% (10/101) in group N and significantly higher at 33.3% (6/18) in group V (P = 0.007). When the presence of D vessels was considered a diagnostic criterion for submucosal cancer, diagnostic accuracy, sensitivity, and specificity were 81.5, 37.5, and 88.3%, respectively. Conclusions. The results suggest that identification of D vessels using ME-NBI can assist in the assessment of invasion depth in EGC. PMID:23401676

Kikuchi, Daisuke; Iizuka, Toshiro; Hoteya, Shu; Yamada, Akihiro; Furuhata, Tsukasa; Yamashita, Satoshi; Domon, Kaoru; Nakamura, Masanori; Matsui, Akira; Mitani, Toshifumi; Ogawa, Osamu; Watanabe, Sumio; Kaise, Mitsuru

2013-01-17

244

Effect of Mean Stress on Fatigue-Crack Growth in Cruciform-Welded Joints Under Non-Stationary Narrow-Band Random Loading.  

National Technical Information Service (NTIS)

Some fatigue tests were carried out in room temperature air at zero and high mean-stress on unstress-relieved cruciform-welded steel joints. The load history used consisted of four different levels of stationary narrow-band random loading arranged in risi...

L. P. Pook

1983-01-01

245

Design and implementation of a low-phase-noise integrated CMOS Frequency Synthesizer for high-sensitivity narrow-band FM transceivers  

Microsoft Academic Search

Frequency Synthesizers (FS) are used in a wide range of RF applications. The narrow-band FM transceivers are usually used in mobile communication network e.g. (AMPS) and public safety applications, which employ a huge number of channels in a limited bandwidth. In such applications, it is required to have a stable local oscillator (LO) signal with minimum phase noise, in order

M. M. Kamal; E. W. El-Shewekh; M. H. El-Saba

2003-01-01

246

Composition of the galactic center star cluster. Population analysis from adaptive optics narrow band spectral energy distributions  

NASA Astrophysics Data System (ADS)

Context: The GC is the closest galactic nucleus, offering the unique possibility of studying the population of a dense stellar cluster surrounding an SMBH. Aims: The goals of this work are to develop a new method of separating early and late type stellar components of a dense stellar cluster based on narrow band filters, applying it to the central parsec of the GC, and conducting a population analysis of this area. Methods: We use AO assisted observations obtained at the ESO VLT in the NIR H-band and 7 intermediate bands covering the NIR K-band. A comparison of the resulting SEDs with a blackbody of variable extinction then allows us to determine the presence and strength of a CO absorption feature to distinguish between early and late type stars. Results: This new method is suitable for classifying K giants (and later), as well as B2 main sequence (and earlier) stars that are brighter than 15.5 mag in the K band in the central parsec. Compared to previous spectroscopic investigations that are limited to 13-14 mag, this represents a major improvement in the depth of the observations and reduces the needed observation time. Extremely red objects and foreground sources can also be reliably removed from the sample. Comparison to sources of known classification indicates that the method has an accuracy of better than ~87%. We classify 312 stars as early type candidates out of a sample of 5914 sources. Several results, such as the shape of the KLF and the spatial distribution of both early and late type stars, confirm and extend previous works. The distribution of the early type stars can be fitted with a steep power law (?1'' = -1.49 ± 0.12), alternatively with a broken power law, ?1-10'' = -1.08 ± 0.12, ?10-20'' = -3.46 ± 0.58, since we find a drop in the early type density at ~10''. We also detect early type candidates outside of 0.5 pc in significant numbers for the first time. The late type density function shows an inversion in the inner 6'', with a power-law slope of ?R<6'' = 0.17 ± 0.09. The late type KLF has a power-law slope of 0.30 ± 0.01, closely resembling the KLF obtained for the bulge of the Milky Way. The early type KLF has a much flatter slope of (0.14 ± 0.02). Our results agree best with an in-situ star formation scenario. A table of all classified sources (5914) is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/499/483

Buchholz, R. M.; Schödel, R.; Eckart, A.

2009-05-01

247

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

SciTech Connect

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.

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

2012-04-05

248

Thermal destruction of spin-polaron bands in the narrow-gap correlated semiconductors FeGa3 and FeSb2.  

PubMed

We report muon spin rotation spectra in the narrow-gap semiconductors FeGa(3) and FeSb(2) consistent with a narrow band of small spin polarons (SPs). The characteristic sizes obtained for these SPs are R(FeGa(3)) ? 0.3-0.6 nm and R(FeSb (2)) ? 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(3) and above 7 K in FeSb(2). Formation of such SP band states can explain many of the low-temperature properties of these materials. PMID:22481069

Storchak, Vyacheslav G; Brewer, Jess H; Lichti, Roger L; Hu, Rongwei; Petrovic, Cedomir

2012-04-05

249

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

250

Dense-type crypt opening seen on magnifying endoscopy with narrow-band imaging is a feature of gastric adenoma.  

PubMed

BACKGROUND: Magnifying endoscopy with narrow-band imaging (ME-NBI) can visualize crypt openings (CO) as slit-like structures in gastric epithelial neoplasia. Visualization of numerous CO is characteristic of low-grade adenoma (LGA). The aim of the present study was to investigate whether visualization of CO by ME-NBI is useful for discriminating between LGA and early gastric cancer (EGC). PATIENTS AND METHODS: Fifty-one superficial elevated-type gastric neoplasias (10 LGA and 41 EGC) were retrospectively evaluated. The presence of CO and the number of CO were evaluated in endoscopic photos obtained at high-power endoscopic magnification by ME-NBI. The optimal cut-off value for the number of CO visualized to discriminate between LGA and EGC was determined by receiver operating characteristic curve analysis. RESULTS: The mean number of CO visualized was significantly larger in the LGA group than in the EGC group (31.2, 95% confidence interval [CI] 16.3-46.1 vs 6.3, 95% CI 3.6-9.0; P?

Kanesaka, Takashi; Sekikawa, Akira; Tsumura, Takehiko; Maruo, Takanori; Osaki, Yukio; Wakasa, Tomoko; Shintaku, Masayuki; Yao, Kenshi

2013-04-01

251

Anisotropic Emission of the X-Ray K-Emission Band of Nitrogen in Hexagonal Boron Nitride.  

National Technical Information Service (NTIS)

The intensity distribution of the N K-emission band of hexagonal boron nitride samples with partially orientated crystallites was found to be strongly dependent upon the take-off angle of the emitted radiation. The observed emission bands can be separated...

E. Tegeler N. Kosuch G. Wiech A. Faessler

1977-01-01

252

Benchmarking of L-band soil microwave emission models  

NASA Astrophysics Data System (ADS)

A first step before assimilating Soil Moisture and ocean Salinity (SMOS) L-band brightness temperatures (Tb) over land is to couple land surface models (LSM) to microwave emission models. In this study, the ISBA LSM is coupled to the Community Microwave Emission Model (CMEM). Simulations of Tb are performed over a 3-yr period (2003-2005) for a bare soil field in southwestern France, at the SMOSREX experimental site. Both ISBA and CMEM present several options for the representation of the soil moisture and soil temperature profiles. Simplified 2-layer simulations are compared with more detailed multilayer simulations. In the 2-layer simulations, the soil is divided in two layers (a thin surface layer and a bulk reservoir), and Fresnel laws are used in CMEM to model the smooth surface emissivity. In the multilayer simulations, the ISBA soil diffusion scheme is used (with 11 soil layers represented) together with the Wilheit (1978) option of CMEM. The Tb simulations are compared to the Tb ground observations available for the SMOSREX site, at H and V polarizations and at different angles and the impact of soil roughness is assessed. It is shown that Tb values derived from the more complex multilayer simulations correlate better to the observations than Tb derived from the 2-layer model. This is partly due to a better representation of the soil moisture profile. However, taking surface soil moisture into account in the calculation of soil roughness is needed to represent the seasonal trend of Tb produced by the multilayer model. Finally, the multilayer model is used to investigate the L-band sampling depth for contrasting soil texture profiles. For the SMOSREX soil texture, it is found that Tb is mainly driven by the top 15 cm soil layer. However, from May to October, a significant part of the signal originates from deeper soil layers, and an accuracy of ±0.1 K can be achieved by representing a multilayer soil profile from the surface to a depth of 35 cm.

Calvet, Jean-Christophe; Parrens, Marie; de Rosnay, Patricia; Decharme, Bertrand

2013-04-01

253

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

PubMed

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

Lee, Tsung-Chun; Lin, Yu-Huei; Uedo, Noriya; Wang, Hsiu-Po

2013-07-01

254

Narrow-band Bragg filters for the 1.5-{mu}m spectral region based on polished-side single-mode silica fibres  

SciTech Connect

Narrow-band reflecting filters for the telecommunication 1.5-{mu}m wavelength region are fabricated. They consist of a single-mode silica fibre with a polished side and a periodic relief Bragg grating located in the region of the fibre-mode propagation. The filters have the reflectivity R > 98 % and an almost rectangular reflection band with a width of 0.58 - 0.78 nm. They can be used as elements of optical multiplexers/demultiplexers for combining and separating signals in high-speed multichannel fibreoptic communication lines. (fibre optics)

Sokolov, Viktor I; Khudobenko, A I [Institute of Laser and Information Technologies, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation)

2003-06-30

255

Narrow band gap, high photosensitivity a-SiGe:H films prepared by hot wire chemical vapor deposition (HW-CVD) method  

Microsoft Academic Search

In this letter, we report narrow band gap (1.39–1.53 eV) a-SiGe:H films with high photosensitivity (?104–105) are grown successfully by HW-CVD using a mixture of (GeH4+SiH4) at low flow rates and without hydrogen dilution with higher deposition rates (>10 Å\\/s). These films are characterized by Raman spectroscopy, FTIR spectroscopy and UV–Visible spectroscopy. The band gap of a-SiGe:H films can be

S. R Jadkar; J. V Sali; S. T Kshirsagar; M. G Takwale

2002-01-01

256

Fabrication and investigation of imaging normal-incidence multilayer mirrors with a narrow-band reflection in the range lambda simeq 4.5 nm  

Microsoft Academic Search

Soft X-ray spherical normal-incidence mirrors (D = 60 mm, r = 2000 mm) with metal-carbon multilayer coatings, which provide a narrow-band reflection in the spectral range lambda ~ 4.5 nm, have been synthesized using the pulsed laser deposition technique. The peak reflectivity of the multilayers reaches 13%, and the wavelength-to-bandwidth ratio lambda\\/Deltalambda ~ 80. The spectral characteristics of the mirrors

A. D. Akhsakhalyan; N. N. Kolachevsky; M. M. Mitropolsky; E. N. Ragozin; N. N. Salashchenko; V. A. Slemzin

1993-01-01

257

Novel compact elliptic-function narrow-band bandpass filters using microstrip open-loop resonators with coupled and crossing lines  

Microsoft Academic Search

Novel compact elliptic-function narrow-band bandpass filters have been designed and fabricated. This new configuration consists of two identical microstrip open-loop resonators with coupled and crossing lines. A theoretical investigation has confirmed that this novel configuration is capable of providing elliptic-function filtering. Furthermore, the feasibility of this filter is verified experimentally. Centered at 2.039 GHz, the fabricated microstrip bandpass filter shows

Cheng-Cheh Yu; Kai Chang

1998-01-01

258

Xenon chloride ultraviolet B laser is more effective in treating psoriasis and in inducing T cell apoptosis than narrow-band ultraviolet B  

Microsoft Academic Search

Earlier we reported that a 308-nm xenon chloride (XeCl) UVB laser is highly effective for treating psoriasis. As ultraviolet B light seems to cause T cell apoptosis, in the present study we studied the ability of the XeCl laser to induce T-cell apoptosis in vitro, and then compared the apoptosis-inducing capacities of narrow-band UVB (NB-UVB) light and the XeCl laser.

Zoltán Novák; Béla Bónis; Eszter Baltás; Imre Ocsovszki; Ferenc Ignácz; Attila Dobozy; Lajos Kemény

2002-01-01

259

The H alpha Galaxy Survey I. The galaxy sample, H alpha narrow-band observations and star formation parameters for 334 galaxies  

Microsoft Academic Search

We discuss the selection and observations of a large sample of nearby\\u000agalaxies, which we are using to quantify the star formation activity in the\\u000alocal Universe. The sample consists of 334 galaxies across all Hubble types\\u000afrom S0\\/a to Im and with recession velocities of between 0 and 3000 km\\/s. The\\u000abasic data for each galaxy are narrow band

P. A. James; N. S. Shane; J. E. Beckman; A. Cardwell; C. A. Collins; J. Etherton; R. S. de Jong; K. Fathi; J. H. Knapen; R. F. Peletier; S. M. Percival; D. L. Pollacco; M. S. Seigar; S. Stedman; I. A. Steele

2003-01-01

260

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

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

Mark D. Shriver; Esteban J. Parra

2000-01-01

261

Comparative study of conventional colonoscopy and pan-colonic narrow-band imaging system in the detection of neoplastic colonic polyps: a randomized, controlled trial  

Microsoft Academic Search

Background. Detection and removal of adenomas by colonoscopy is an important means for preventing cancer; however, small adenomas may\\u000a be missed during colonoscopy. The narrow-band imaging (NBI) system clearly enhances the microvasculature in neoplastic lesions,\\u000a making it appear as a dark complex. Therefore, the NBI system may improve the detection of colonic neoplasias. However, no\\u000a randomized, controlled trials have evaluated

Takuya Inoue; Mitsuyuki Murano; Naoko Murano; Takanori Kuramoto; Ken Kawakami; Yosuke Abe; Eijiro Morita; Ken Toshina; Hideo Hoshiro; Yutaro Egashira; Eiji Umegaki; Kazuhide Higuchi

2008-01-01

262

Multi-tap complex-coefficient incoherent microwave photonic filters based on optical single-sideband modulation and narrow band optical filtering.  

PubMed

We propose a novel scheme to implement tunable multi-tap complex coefficient filters based on optical single sideband modulation and narrow band optical filtering. A four tap filter is experimentally demonstrated to highlight the enhanced tuning performance provided by complex coefficients. Optical processing is performed by the use of a cascade of four phase-shifted fiber Bragg gratings specifically fabricated for this purpose. PMID:18521161

Sagues, Mikel; García Olcina, Raimundo; Loayssa, Alayn; Sales, Salvador; Capmany, José

2008-01-01

263

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)

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.

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

1999-07-01

264

Satellite observations of banded VLF emissions in conjunction with energy-banded ions during very large geomagnetic storms  

NASA Astrophysics Data System (ADS)

Electromagnetic VLF emissions banded in frequency, coincident with warm energy-banded ions in the low latitude auroral zone, and associated with very strong geomagnetic storms, are observed separately on two low-earth polar orbiting satellites, FAST and DEMETER. Both satellites carry a full complement of field and particle detectors. The FAST satellite, launched August 21, 1996 into an elliptical polar orbit with perigee 350 km and apogee 4175 km, traversed the auroral zone four times per orbit across a wide range of altitudes and local times. The DEMETER satellite was launched on June 29, 2004 into a circular sun-synchronous polar orbit at altitude 710 km, with data recorded at all invariant latitudes less than ~65 degrees. The ion bands were first reported in association with the Halloween storms [Cattell et al., 2004; Kozyra et al., 2004, Yao et al., 2008]. Banded ions are observed on FAST during every large magnetic storm in discrete energy bands at energies ~10 eV - 10 keV and lasting up to 12 hrs. The energy flux peaks in the trapped population but is also evident in the precipitating ions, and in certain cases a significant upgoing ion component appears at low invariant latitudes. These bands were observed over several orbits at similar latitudes in both dawn and evening sectors, with the signature typically more pronounced in the dawn sector. In this study we focus on the coincidence of the energy-banded ions with observations of frequency-banded VLF electromagnetic emissions. During all of these very large storms, banded VLF emissions are evident in both the electric and magnetic field, appearing as discrete frequency bands between ~100 and ~1500 Hz separated by 75-150 Hz. These banded emissions persist for several FAST or DEMETER orbits, lasting up to 10 hrs, in both the northern and southern hemispheres. There appears to be a correlation between the banded wave observations and ion and electron density enhancements. Possible generation mechanisms for the banded emissions include EMIC waves generated in the equatorial ring current region which bounce to higher L-shells and propagate down auroral field lines to the spacecraft location.

Colpitts, C. A.; Cattell, C. A.; Kozyra, J. U.; Parrot, M.

2010-12-01

265

Fast Hearing-Threshold Estimation Using Multiple Auditory Steady-State Responses with Narrow-Band Chirps and Adaptive Stimulus Patterns  

PubMed Central

This paper describes the estimation of hearing thresholds in normal-hearing and hearing-impaired subjects on the basis of multiple-frequency auditory steady-state responses (ASSRs). The ASSR was measured using two new techniques: (i) adaptive stimulus patterns and (ii) narrow-band chirp stimuli. ASSR thresholds in 16 normal-hearing and 16 hearing-impaired adults were obtained simultaneously at both ears at 500, 1000, 2000, and 4000?Hz, using a multiple-frequency stimulus built up of four one-octave-wide narrow-band chirps with a repetition rate of 40?Hz. A statistical test in the frequency domain was used to detect the response. The recording of the steady-state responses was controlled in eight independent recording channels with an adaptive, semiautomatic algorithm. The average differences between the behavioural hearing thresholds and the ASSR threshold estimate were 10, 8, 13, and 15?dB for test frequencies of 500, 1000, 2000, and 4000?Hz, respectively. The average overall test duration of 18.6 minutes for the threshold estimations at the four frequencies and both ears demonstrates the benefit of an adaptive recording algorithm and the efficiency of optimised narrow-band chirp stimuli.

Muhler, Roland; Mentzel, Katrin; Verhey, Jesko

2012-01-01

266

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

PubMed

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

Ferguson, B G; Lo, K W

2000-10-01

267

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

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.

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

268

Detection of marine methane emissions with AVIRIS band ratios  

NASA Astrophysics Data System (ADS)

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.

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

2011-05-01

269

A New Dual-Component Photoionization Model for the Narrow Emission Line Regions in Active Galactic Nuclei  

NASA Astrophysics Data System (ADS)

Having found that type 1 Seyfert nuclei have excess [Fe VII] lambda 6087 emission with respect to type 2 nuclei, Murayama & Taniguchi have proposed that the high-ionization nuclear emission line region (HINER) traced by the [Fe VII] lambda 6087 emission resides in the inner wall of dusty tori. The covering factor of the torus is usually large (e.g., ~0.9). Further, electron density in the tori (e.g., ~107-108 cm-3) is considered to be significantly higher than that (e.g., ~103-104 cm-3) in the narrow-line region (NLR). Therefore, it is expected that the torus emission contributes to the majority of the higher ionization emission lines. Taking this HINER component into account, we have constructed new dual-component (i.e., a typical NLR with a HINER torus) photoionization models. Comparison of our model with the observations shows that if the torus emission contributes ~10% of the NLR emission, our dual-component model can explain the observed high [Fe VII] lambda 6087/[O III] lambda 5007 intensity ratios of the Seyfert 1 nuclei without invoking any unusual assumptions (e.g., the overabundance of iron).

Murayama, Takashi; Taniguchi, Yoshiaki

1998-08-01

270

A compact band-stop\\/band-pass filter using a narrow gap capacitive as J-inverter and a new octagonal defected ground structure (DGS)  

Microsoft Academic Search

In this paper, we proposed a new compact DGS band-stop filter with broad passband and low insertion loss in the stop-band. The philosophy of the structure behind this new microstrip band-stop filter is simple as it is composed of a pair of octagonal DGS-slots and an open-stub as compensated microstrip capacitance. The filter will be realized through direct electromagnetic coupling

A. Boutejdar; A. Batmanov; A. Omar; E. Burte

2009-01-01

271

Effective strain-induced band gap narrowing of anatase TiO2: A soft crystal direction  

Microsoft Academic Search

TiO2 is one of the promising materials for photoelectrochemical hydrogen production through water splitting. However, due to its large band gap (3.2. eV), it cannot absorb sun light effectively. To reduce its band gap, various approaches have been attempted, including applying strain. Using first-principles band structure method, we have studied the electronic and elastic properties of TiO2 with anatase and

Wan-Jian Yin; Xin-Gao Gong; Su-Huai Wei

2010-01-01

272

Inhibited spontaneous emission of quantum dots observed in a 3D photonic band gap.  

PubMed

We present time-resolved emission experiments of semiconductor quantum dots in silicon 3D inverse-woodpile photonic band gap crystals. A systematic study is made of crystals with a range of pore radii to tune the band gap relative to the emission frequency. The decay rates averaged over all dipole orientations are inhibited by a factor of 10 in the photonic band gap and enhanced up to 2× outside the gap, in agreement with theory. We discuss the effects of spatial inhomogeneity, nonradiative decay, and transition dipole orientations on the observed inhibition in the band gap. PMID:22181609

Leistikow, M D; Mosk, A P; Yeganegi, E; Huisman, S R; Lagendijk, A; Vos, W L

2011-11-03

273

Absorption coefficient of luminescent bodies in the emission band  

Microsoft Academic Search

Einstein's theory associating the coefficients of absorption, induced emission and spontaneous emission cannot be applied to luminescent systems, because the radiative transitions occur with the absorption or emission of phonons. It may be generalised to include luminescent systems by the use of a hollow sphere whose internal walls are covered with a substance irradiated by a Wood lamp, placed at

A. Alexic; K. Nikolic; J. Buric; D. Magnant; H. Payen de La Garanderie

1982-01-01

274

Detections of Lyman Continuum from Star-Forming Galaxies at z ~ 3 through Subaru/Suprime-Cam Narrow-Band Imaging  

NASA Astrophysics Data System (ADS)

Knowing the amount of ionizing photons from young star-forming galaxies is of particular importance to understanding the reionization process. Here we report initial results of a Subaru/Suprime-Cam deep imaging observation of the SSA22 proto-cluster region at z = 3.09, using a special narrow-band filter to optimally trace ionizing radiation from galaxies at z ~ 3. The unique wide field-of-view of Suprime-Cam enabled us to search for ionizing photons from 198 galaxies (73 Lyman break galaxies (LBGs) and 125 Ly? emitters (LAEs)) with spectroscopically measured redshifts z sime 3.1. We detected ionizing radiation from 7 LBGs, as well as from 10 LAE candidates. Some of the detected galaxies show significant spatial offsets of ionizing radiation from nonionizing UV emission. For some LBGs the observed nonionizing UV to Lyman continuum flux density ratios are smaller than values expected from population synthesis models with a standard Salpeter initial mass function (IMF) with moderate dust attenuation (which is suggested from the observed UV slopes), even if we assume very transparent intergalactic medium along the sightlines of these objects. This implies an intrinsically bluer spectral energy distribution, e.g., that produced by a top-heavy IMF, for these LBGs. The observed flux density ratios of nonionizing UV to ionizing radiation of 7 detected LBGs range from 2.4 to 23.8 and the median is 6.6. The observed flux density ratios of the detected LAEs are even smaller than LBGs, if they are truly at z sime 3.1. We find that the median value of the flux density ratio for the detected LBGs suggests that their escape fractions are likely to be higher than 4%, if the Lyman continuum escape is isotropic. The results imply that some of the LBGs in the proto-cluster at z ~ 3 have escape fraction significantly higher than that of galaxies (in a general field) at z ~ 1 studied previously. Some of the data presented in this paper were obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Iwata, I.; Inoue, A. K.; Matsuda, Y.; Furusawa, H.; Hayashino, T.; Kousai, K.; Akiyama, M.; Yamada, T.; Burgarella, D.; Deharveng, J.-M.

2009-02-01

275

A high-velocity ionized outflow and XUV photosphere in the narrow emission line quasar PG1211+143  

NASA Astrophysics Data System (ADS)

We report on the analysis of a ~60-ks XMM-Newton observation of the bright, narrow emission line quasar PG1211+143. Absorption lines are seen in both European Photon Imaging Camera and Reflection Grating Spectrometer spectra corresponding to H- and He-like ions of Fe, S, Mg, Ne, O, N and C. The observed line energies indicate an ionized outflow velocity of ~24 000 km s-1. The highest energy lines require a column density of NH~ 5 × 1023 cm-2, at an ionization parameter of log?~ 3.4. If the origin of this high-velocity outflow lies in matter being driven from the inner disc, then the flow is likely to be optically thick within a radius of ~130 Schwarzschild radii, providing a natural explanation for the big blue bump (and strong soft X-ray) emission in PG1211+143.

Pounds, K. A.; Reeves, J. N.; King, A. R.; Page, K. L.; O'Brien, P. T.; Turner, M. J. L.

2003-11-01

276

The Effect of High N-DOPED Anatase TiO2 on the Band Gap Narrowing and Redshift by First-Principles  

NASA Astrophysics Data System (ADS)

Anatase TiO2 supercells were studied by first-principles, in which one was undoped and another three were high N-doping. Partial densities of states, band structure, population and absorption spectrum were calculated. The calculated results indicated that in the condition of TiO2-xNx (x = 0.0625, 0.125, 0.25), the higher the doping concentration is, the shorter will be the lattice parameters parallel to the direction of c-axis. The strength of covalent bond significantly varied. The formation energy increases at first, and then decreases. The doping models become less stable as N-doping concentration increases. Meanwhile, the narrower the band gap is, the more significant will be the redshift, which is in agreement with the experimental results.

Hou, Qingyu; Jin, Yongjun; Ying, Chun; Zhao, Erjun; Zhang, Yue; Dong, Hongying

2012-10-01

277

Electrically switchable random to photonic band-edge laser emission in chiral nematic liquid crystals  

NASA Astrophysics Data System (ADS)

Using a chiral nematic liquid crystal with a negative dielectric anisotropy, it is possible to switch between band-edge laser emission and random laser emission with an electric field. At low frequencies (<1 kHz), random laser emission is observed as a result of scattering due to electro-hydrodynamic instabilities. However, band-edge laser emission is found to occur at higher frequencies (>5 kHz), where the helix is stabilized due to dielectric coupling. These results demonstrate a method by which the linewidth of the laser source can be readily controlled externally (from 4 nm to 0.5 nm) using electric fields.

Morris, Stephen M.; Gardiner, Damian J.; Hands, Philip J. W.; Qasim, Malik M.; Wilkinson, Timothy D.; White, Ian H.; Coles, Harry J.

2012-02-01

278

N2 triplet band emissions in the dayglow of Venus, Mars, and Titan  

NASA Astrophysics Data System (ADS)

Vegard-Kaplan (VK) and Second Positive emissions of N_2 are common features in the terrestrial dayglow and aurora and have been studied extensively. Recent discoveries of N_2 triplet band emissions on Mars by SPICAM/Mars-Express and on Titan by Cassini UVIS have led planetary scientists to look for the processes governing the N_2 triplet band emissions in different planetary atmospheres. Present work deals with the modeling of N_2 triplet band emission on Mars, Venus, and Titan. A model for N_2 triplet band emissions has been developed and used to explain the recent observations of N_2 Vegard-Kaplan (VK) (A^3?_u^+ - X^1?^+_g ) band on Mars and Titan. Steady state photoelectron fluxes and volume excitation rates have been calculated using the Analytical Yield Spectra technique. Since interstate cascading is important for triplet states of N_2, the population of any given level of N_2 triplet states is calculated under statistical equilibrium considering direct excitation, cascading, and quenching effects. Relative population of all vibrational levels of each triplet state is calculated in the model. Line of sight intensities and height-integrated overhead intensities have been calculated for VK, First Positive ( B^3?_g - A^3?^+_u ), Second Positive ( C^3?_u - B^3?_g ), Wu-Benesch (W^3?_u - B^3?_g), Reverse First Positive, Herman--Kaplan (E ? A), E ? B, and E ? C bands of N_2. The N_2 VK band span wavelength range from far ultraviolet to visible, and some transitions even originate at wavelength more than 1000 nm . Our calculations show that the overhead intensity of VK bands in the wavelength range 400--800, 300--190, 200--300, and 150--200 nm are 22%, 39%, 35%, and 4% of the total VK band emission. Emissions between 600 and 800 nm wavelength consist of about 50% of the total First Positive band system. Major portion of Second Positive band emissions lie in wavelengths between 300 and 400 nm, which is more than 90% of the total Second Positive band overhead intensity. On Mars, a reduction in the N_2 density by a factor of 3 in the Mars thermospheric general circulation model is required to obtain agreement between calculated limb profiles of VK (0-6) and the SPICAM/MEX observation. On Titan, the calculated intensity of N_2 VK band in 150--190 nm wavelength range is in good agreement with the Cassini-UVIS observation. Calculations are also carried out on Venus using this model. Calculated intensities on Venus are about factor of 10 higher than that on Mars. The results will be presented and discussed.

Jain, Sonal Kumar; Bhardwaj, Anil

2012-07-01

279

Connection between Mid-infrared Emission Properties and Narrow-line Region Outflows in Type 1 Active Galactic Nuclei  

NASA Astrophysics Data System (ADS)

The location of warm dust producing the mid-infrared (MIR) emission in type 1 active galactic nuclei (AGNs) is complex and not yet fully known. We explore this problem by studying how the MIR covering factor (CFMIR = L MIR/L bol) correlates with the fundamental parameters of AGN accretion process (such as L bol, black hole mass M BH, and Eddington ratio L/L Edd) and the properties of narrow emission lines (as represented by [O III] ?5007), using large data sets derived from the Sloan Digital Sky Spectroscopic Survey (SDSS) and the Wide Infrared Sky Survey (WISE). First, we find that the luminosity of the [O III] wing component (L wing) correlates more tightly with the continuum luminosity (?L ?(5100)) than the luminosity of the line core component (L core) does, which is in line with our previous conclusion that the wing component, generally blueshifted, originates from the polar outflows in the inner narrow-line region (NLR). We then find that the MIR CF shows the strongest correlation with L wing/L bol rather than with L core/L bol or the above fundamental AGN parameters, and the correlation becomes stronger as the infrared wavelength increases. We also confirm the anti-correlations of CFMIR with L bol and M BH, and the lack of dependence of CFMIR on the Eddington ratio. These results suggest that a large fraction of the warm dust producing MIR emission in AGNs is likely embedded in polar outflows in the NLR instead of in the torus.

Zhang, Kai; Wang, Ting-Gui; Yan, Lin; Dong, Xiao-Bo

2013-05-01

280

Technology of InP-based 1.55-?m ultrafast OEMMICs: 40-Gbit\\/s broad-band and 38\\/60GHz narrow-band photoreceivers  

Microsoft Academic Search

For future long-haul communication systems operating at bitrates of 40 Gbit\\/s and for broad-band mobile access systems using 38- or 60-GHz carrier frequencies, ultrafast photoreceivers have to be provided. Therefore, an integration concept for InP-based optoelectronic microwave monolithic integrated circuits for the 1.55-?m wavelength regime is demonstrated, which allows independent optimization of the constituting devices. Two different types of photodetectors

Andreas Umbach; Thomas Engel; Heinz-Gunter Bach; Stefan van Waasen; E. Droge; A. Strittmatter; W. Ebert; W. Passenberg; R. Steingruber; W. Schlaak; G. G. Mekonnen; G. Unterborsch; D. Bimberg

1999-01-01

281

A modified k-distribution approach applied to narrow band water vapour and oxygen absorption estimates in the near infrared  

Microsoft Academic Search

We apply a modified version of the k-distribution method to derive expressions for the total and in-layer transmission of layered atmospheres in the H2O and O2 absorption bands around 900 and 762 nm, respectively. The calculations are exemplary performed for the channels settings of the forthcoming Medium Resolution Imaging Spectrometer (MERIS), to be launched onboard ESA's Environmental Satellite in 2000,

Ralf Bennartz; Jürgen Fischer

2000-01-01

282

Design of narrow-band DBR planar filters in Si-BCB technology for millimeter-wave applications  

Microsoft Academic Search

This paper discusses a method used to design planar bandpass filters for millimeter-wave applications in U- and W-band frequency ranges. For technical reasons, these filters have to be implemented on silicon-based technology. So as to decrease the insertion losses levels inherent in silicon substrate, we propose a thin-film microstrip-like technology implemented on a benzocyclobutene layer. In addition, a dual-behavior resonator-based

Gaëtan Prigent; Eric Rius; F. Le Pennec; S. Le Maguer; C. Quendo; H. Happy

2004-01-01

283

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

SciTech Connect

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.

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

284

Model calculation of N2 Vegard-Kaplan band emissions in Martian dayglow  

Microsoft Academic Search

First detailed model of N2 Vegard-Kaplan Band dayglow emissions on MarsN2 density in Mars TGC model should be reduced by a factor of 3N2\\/CO2 ratio is constrained by SPICAM observed VK emission profiles

Sonal Kumar Jain; Anil Bhardwaj

2011-01-01

285

Optical Absorption and Emission Bands of SiC 2 in Carbon Stars  

NASA Astrophysics Data System (ADS)

Observations of the Merrill-Sanford bands of SiC2 in the 4750--5050 A spectral region, seen in absorption in some carbon stars and in emission in IRAS 12311-3509, are reported. Vibrational band assignments based on recent laser-based laboratory electronic spectroscopy of this molecule constitute substantial revisions compared with earlier work. Vibrational hot bands are very strong when present in carbon stars, but were greatly weakened in T Mus for a time in 1994, indicating that the bands were then formed in a cooler region than that typical of carbon star photospheres. Emission bands of SiC2, with intensities that are consistent with optical excitation of cool gas, appear in IRAS 12311-3509 which is probably a J-type carbon star occulted by a dusty disk so that the star is seen by reflection from material out of the plane of the disk.

Sarre, P. J.; Hurst, M. E.; Lloyd Evans, T.

1996-11-01

286

A Narrow-band 8.7 GHz SiGe HBT LNA with a Passive Frequency Selective Feedback  

NASA Astrophysics Data System (ADS)

This paper presents a low noise amplifier (LNA) with differential output using a passive frequency selective feedback. The introduced feedback stabilizes the amplifier at lower frequencies and improves the gain in the desired frequency band. The LNA consists of two stages. Additionally, a buffer at the output is added for measurements. The amplifier was implemented in a 0.35 ?m SiGe technology. For measurements the LNA was bonded to a substrate. A peak gain of 28.1 dB and a minimum noise figure of 2.2 dB at a supply voltage of 3 V were achieved.

Gerlich, Stefan; Weger, Peter

2012-06-01

287

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

Microsoft Academic Search

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

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

288

Satellite observations of banded VLF emissions in conjunction with energy-banded ions during very large geomagnetic storms  

NASA Astrophysics Data System (ADS)

Frequency-banded electromagnetic VLF waves up to 2000 Hz are observed concurrently with warm (10 s to 10,000 s of eV) energy-banded ions in the low latitude auroral and sub-auroral zones during every large geomagnetic storm encountered by the FAST and DEMETER satellites. The banded ions and waves persist for several FAST or DEMETER orbits, lasting up to 12 h, in both dawn and dusk sectors, in both the northern and southern hemispheres. If the waves are generated at harmonics of the proton gyrofrequency, the inferred source region would be ?4000 km altitude. Previous investigations have shown that such waves can propagate from this source region to the locations of both spacecraft. An investigation into the growth of waves at harmonics of fci in the inferred source region suggests that these emissions could be generated by ion bands similar to those observed at the same time as the waves. Magnetospheric waves such as these play a role in energy transfer between distinct particle populations and may contribute to ion heating and ion outflow as well as electron energization. All of these phenomena occur during the strongest magnetic storms. The appearance of the banded ions and associated wave activity suggests that there may be distinct changes in the geospace system that characterize large magnetic storms.

Colpitts, Christopher A.; Cattell, Cynthia A.; Kozyra, Janet U.; Parrot, Michel

2012-10-01

289

Broadband femtosecond OPCPA system driven by the single-shot narrow-band iodine photodissociation laser SOFIA  

NASA Astrophysics Data System (ADS)

A two-stage optical parametric amplifier driven by a frequency-tripled beam from the high-energy iodine laser system SOFIA was built. This single-shot Optical Parametric Chirped Pulse-Amplification facility (OPCPA) and the system synchronizing the pump and signal pulses are described in detail. The chirped seed pulse of a Ti:sapphire oscillator running at the central wavelength of 800 nm is amplified in the two-stage (LBO and KDP) optical parametric amplifier over 108 times. The amplified spectral bandwidth of 68 nm corresponds to the pulse duration of 14 fs when a transform-limited pulse is assumed. This implies a compressed pulse of TW power. Systematic gain measurements reveal a good match with the theoretical predictions. Signal and idler beam fluence profiles are presented. The suitability of the iodine photo-dissociation laser as a pump source for the OPCPA technique is thus proved for the first time experimentally. A distinctive feature of the iodine laser is its very narrow gain bandwidth (<0.1 cm-1) and, therefore, the conventional chirped-pulse amplification technique does not lead to pulse durations at the femtosecond level.

Novák, O.; Tur?i?ová, H.; Smrž, M.; Huynh, J.; Pfeifer, M.; Straka, P.

2012-09-01

290

EXTENDED NARROW-LINE EMISSION IN THE BRIGHT SEYFERT 1.5 GALAXY HE 2211-3903  

SciTech Connect

Extended narrow-line regions (ENLRs) and extended emission-line regions have been the focus of integral field spectroscopy aiming at the inner kiloparsecs of nearby Seyfert galaxies as well as the larger environment of high-redshift QSOs. Based on observations with the Wide Field Spectrograph at the 2.3 m telescope of the Australian National University, we present spatially resolved emission-line diagnostics of the bright Seyfert 1.5 galaxy HE 2211-3903 which is drawn from a sample of the brightest Seyfert galaxies at z < 0.06 with luminosities around the classical Seyfert/QSO demarcation. In addition to the previously known spiral arms of HE 2211-3903, the emission-line maps reveal a large-scale ring with a radius of about 6 kpc which is connected to the active galactic nucleus (AGN) through a bar-like structure. The overall gas kinematics indicates a disk rotation pattern. The emission-line ratios show Seyfert-type, H II region-type, and composite classifications, while there is no strong evidence of LINER-type ratios. Shock ionization is likely to be negligible throughout the galaxy. The composite line ratios are explained via a mixing line between AGN and H II region photoionization. Composite line ratios are predominantly found in between the H II regions in the circum-nuclear region, the bar-like structure to the east of the nucleus, and the eastern half of the ring, suggesting AGN photoionization of the low-density interstellar medium in an ENLR on galaxy scales. The line ratios in the nucleus indicate N enrichment, which is discussed in terms of chemical enrichment by Wolf-Rayet and asymptotic giant branch stars during past and ongoing nuclear starburst activity.

Scharwaechter, J.; Dopita, M. A. [Research School of Astronomy and Astrophysics, The Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek 2611 (Australia); Zuther, J.; Fischer, S.; Eckart, A. [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Strasse 77, 50937 Koeln (Germany); Komossa, S., E-mail: julia@mso.anu.edu [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, 85741 Garching (Germany)

2011-08-15

291

Narrow-band pass filter array for integrated opto-electronic spectroscopy detectors to assess esophageal tissue  

PubMed Central

A strategy for spectroscopy tissue diagnosis using a small number of wavelengths is reported. The feasibility to accurately quantify tissue information using only 16 wavelengths is demonstrated with several wavelength reduction simulations of the existing esophageal data set. These results are an important step for the development of a miniaturized, robust and low-cost spectroscopy system. This system is based on a sub-millimeter high-selective filter array that offers prospects for a simplified miniature spectrographic detector for a future diagnostic tool to improve the diagnosis of dysplasia. Several thin-film optical filters are optimized and fabricated and its spectral performance is shown to be sufficient for the selection of specific wavelength bands.

Ferreira, Debora S.; Mirkovic, Jelena; Wolffenbuttel, Reinoud F.; Correia, Jose H.; Feld, Michael S.; Minas, Graca

2011-01-01

292

An analysis of the information dependence between MODIS emissive bands  

Microsoft Academic Search

Multispectral, hyperspectral and ultraspectral imagers and sounders are increasingly important for atmospheric science and weather forecasting. The recent advent of multipsectral and hyperspectral sensors measuring radiances in the emissive IR are providing valuable new information. This is due to the presence of spectral channels (in some cases micro-channels) which are carefully positioned in and out of absorption lines of CO2,

Srikanth Gottipati; Irina Gladkova; Michael Grossberg

2008-01-01

293

Photoelectric emission from negative-electron-affinity diamond (111) surfaces: Exciton breakup versus conduction-band emission  

SciTech Connect

We have recently reported that bound electron-hole pairs (Mott-Wannier excitons) are the dominant source of photoelectron emission from specially prepared [``as-polished`` C(111)-(1{times}1):H] negative-electron-affinity diamond surfaces for near-band-gap excitation up to 0.5 eV above threshold [C. Bandis and B. B. Pate, Phys. Rev. Lett. 74, 777 (1995)]. It was found that photoexcited excitons transport to the surface, break up, and emit their electron. In this paper, we extend the study of exciton-derived emission to include partial yield (constant final-state) analysis as well as angular distribution measurements of the photoelectric emission. In addition, we find that exciton-derived emission does not always dominate. Photoelectric emission properties of the {ital in} {ital situ} ``rehydrogenated`` (111)-(1{times}1):H diamond surface are characteristically different than emission observed from the as-polished (111)-(1{times}1):H surface. The rehydrogenated surface has additional downward band bending as compared to the as-polished surface. In confirmation of the assignment of photoelectric yield to exciton breakup emission, we find a significant enhancement of the total electron yield when the downward band bending of the hydrogenated surface is increased. The functional form of the observed total electron yield demonstrates that, in contrast to the as-polished surface, conduction-band electrons are a significant component of the observed photoelectric yield from the {ital in} {ital situ} hydrogenated (111)-(1{times}1):H surface. Furthermore, electron emission characteristics of the rehydrogenated surface confirms our assignment of a Fan phonon-cascade mechanism for thermalization of excitons.

Bandis, C.; Pate, B.B. [Department of Physics, Washington State University, Pullman, Washington 99164-2814 (United States)

1995-10-15

294

Generation of powerful narrow-band 75-GHz radiation in a free-electron maser with two-dimensional distributed feedback  

NASA Astrophysics Data System (ADS)

A planar generator based on a free-electron maser (FEM generator) is developed employing a relativistic sheet electron beam (0.8 MeV/1 kA/4 ?s) formed by an ELMI accelerator. A hybrid two-mirror resonator consisting of a two-dimensional upstream and a one-dimensional downstream Bragg reflectors is used as the electrodynamic system. The use of two-dimensional distributed feedback implemented in the upstream Bragg structure has made it possible to achieve stable well reproducible single mode generation regime with transverse dimensions of the system of ˜25 × 2.5 wavelengths. Experiments carried out at a frequency of 75 GHz have yielded narrow-band radiation with spectrum width of ˜20 MHz in pulses with a duration of ˜100-200 ns and power of 30-50 MW.

Arzhannikov, A. V.; Ginzburg, N. S.; Zaslavsky, V. Yu.; Kalinin, P. V.; Peskov, N. Yu.; Sergeev, A. S.; Sinitsky, S. L.; Stepanov, V. D.; Thumm, M.

2013-09-01

295

The contribution of narrow band and modulation of thermoelectric performance in doped layered cobaltites Bi2Sr2Co2Oy  

NASA Astrophysics Data System (ADS)

We have performed the temperature dependence of resistivity ?(T) and thermoelectric power S(T) by a series of doping in layered cobaltites Bi2Sr2Co2Oy. For all samples, a metallic ?(T) behavior and a large temperature-independent S is observed at higher temperatures, while we found a upturning ?(T) but without corresponding variation of S(T) at lower temperatures. The present results strongly demonstrate the contribution of narrow band. Moreover, the doping could effectively modulate the thermoelectric performance. Especially for Bi2Sr1.9Ca0.1Co2Oy, it may provide an excellent platform to be a promising candidate of thermoelectric materials.

Yin, L. H.; Ang, R.; Huang, Y. N.; Jiang, H. B.; Zhao, B. C.; Zhu, X. B.; Song, W. H.; Sun, Y. P.

2012-04-01

296

Molecular structure of the argon-(Z)-1-chloro-2-fluoroethylene complex from chirped-pulse and narrow-band Fourier transform microwave spectroscopy  

NASA Astrophysics Data System (ADS)

Broadband chirped pulse, Fourier transform microwave spectra in the 6-18 GHz region are obtained for the 35Cl and 37Cl isotopomers of the complex formed between argon and (Z)-1-chloro-2-fluoroethylene. Analysis of the spectra provides predictions of rotational transition frequencies for the two singly substituted 13C isotopomers of Ar-35ClHCCHF sufficient to narrow the search range required for observation in a more sensitive, narrow band cavity Fourier transform instrument. Only a non-planar structure with the argon atom maximizing the number of its contacts with preferably heavy atoms is consistent with the rotational constants for all four isotopomers, and no evidence of tunneling between the two equivalent minima on either side of the ethylene plane is found. Rotational transitions for four isotopomers of (Z)-1-chloro-2-fluoroethylene itself, appearing in the broadband spectrum, are analyzed to determine the complete chlorine nuclear quadrupole coupling tensor for this molecule, and when these are combined with the hyperfine constants determined for the complex with argon, the sign ambiguity of the measured off-diagonal tensor components is removed.

Marshall, Mark D.; Leung, Helen O.; Calvert, Catherine E.

2012-10-01

297

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

PubMed

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

Fekete, Szabolcs; Fekete, Jeno

2011-06-17

298

Predicting Thaumastocoris peregrinus damage using narrow band normalized indices and hyperspectral indices using field spectra resampled to the Hyperion sensor  

NASA Astrophysics Data System (ADS)

Thaumastocoris peregrinus (T. peregrinus) is a sap sucking insect that feeds on Eucalyptus leaves. It poses a threat to the forest industry by reducing the photosynthetic ability of the tree, resulting in stunted growth and even death of severely infested trees. Remote sensing techniques offer the potential to detect and map T. peregrinus infestations in plantation forests using current operational hyperspectral scanners. This study resampled field spectral data measured from a field spectrometer to the band settings of the Hyperion sensor in order to assess its potential in predicting T. peregrinus damage. Normalized indices based on NDVI ratios were calculated using the resampled visible and near-infrared bands of the Hyperion sensor to assess its utility in predicting T. peregrinus damage using Partial Least Squares (PLS) regression. The top 20 normalized indices were based on specific biochemical absorption features that predicted T. peregrinus damage with a mean bootstrapped R2 value of 0.63 on an independent test dataset. The top 20 indices were located in the near-infrared region between 803.3 nm and 894.9 nm. Twenty three previously published hyperspectral indices which have been used to assess stress in vegetation were also used to predict T. peregrinus damage and resulted in a mean bootstrapped R2 value of 0.59 on an independent test dataset. The datasets were combined to assess its collective strength in predicting T. peregrinus damage and significant indices were chosen based on variable importance scores (VIP) and were then entered into a PLS model. The indices chosen by VIP predicted T. peregrinus damage with a mean bootstrapped R2 value of 0.71 on an independent test dataset. A greedy backward variable selection model was further tested on the VIP selected indices in order to find the best subset of indices with the best predictive accuracy. The greedy backward variable selection model identified 3 indices and performed the best by predicting damage with an R2 value of 0.74 with the lowest RMSE of 1.30% on an independent test dataset. The best three indices identified include the anthocyanin reflectance index, carotenoid reflectance index and the normalized index calculated at 864.4 and 884.7 nm. Individual relationships between these indices and T. peregrinus damage indicate that high correlations are obtained with the inclusion of a few severely infested trees in the sample size. When the severely infested trees were removed from the study, the normalized index (864.4 and 884.7 nm) and the anthocyanin reflectance index still yielded significant correlations at the 99% confidence interval. This study indicates the significance of normalized indices and spectral indices calculated from the visible and near-infrared bands in hyperspectral data for the prediction of T. peregrinus damage.

Oumar, Z.; Mutanga, O.; Ismail, R.

2013-04-01

299

Search for a narrow annihilation feature correlated with the MeV emission of Cygnus X-1  

SciTech Connect

Strong gamma-ray emission near 1 MeV from Cygnus X-1 observed in the fall of 1979 during the 'gamma 1' period has been interpreted by Liang and Dermer (1988) as thermal emission from a relativistic, pair-dominated region surrounding the black hole. The observed gamma-rays should interact with each other and with X-rays to form electron/positron pairs inside and outside the accretion disk. Because the Eddington limit is reduced by a factor of 1836 in the presence of positrons, some pairs formed inside the disk may also escape the system under the influence of radiation pressure. If these pairs stop in the cold surrounding medium, a narrow 511 keV annihilation feature should be produced. The high resolution gamma 1 spectrum has been examined for such a feature, and some evidence at 1.9 sigma statistical significance for the line is observed with a flux which is generally consistent with theoretical expectations. 16 refs.

Ling, J.C.; Wheaton, WM.A. (California Institute of Technology, Pasadena (USA))

1989-08-01

300

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

NASA Astrophysics Data System (ADS)

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 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 quantum dots in an optimized process that maintains a slow growth rate of the shell through the use of octanethiol and cadmium oleate as precursors. In contrast with previous observations, single-dot blinking is significantly suppressed with only a relatively thin shell. Furthermore, we demonstrate the elimination of the ensemble luminescence photodarkening that is an intrinsic consequence of quantum dot blinking statistical ageing. Furthermore, the small size and high photoluminescence quantum yields of these novel quantum dots render them superior in vivo imaging agents compared with conventional quantum dots. We anticipate these quantum dots will also result in significant improvement in the performance of quantum dots in other applications such as solid-state lighting and illumination.

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.

2013-05-01

301

Fourier Transform Emission Spectra of the (000)-(000) Band of the ?4051.6 Band of C3  

NASA Astrophysics Data System (ADS)

The (000)-(000) band of the 4051.6 Å group (A˜1?u-X˜1?+g) of C3 was recorded in emission with a Bruker IFS 120HR Fourier transform (FT) spectrometer at the University of Waterloo. The band was excited by a microwave discharge in isopropanol (less than a few mtorr) diluted in helium (2 torr). Our new FT data provide more reliable and accurately calibrated transition wavenumbers than those from the grating spectra given by Gausset and coworkers. Analysis of our new spectrum combined with the data by McCall and coworkers confirmed that the lower J levels in the A˜ state were strongly perturbed, as reported by Gausset and coworkers. The unidentified lines observed by McCall and coworkers could be attributed to extra transitions to an unknown perturbing state.

Tanabashi, A.; Hirao, T.; Amano, T.; Bernath, P. F.

2005-05-01

302

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

SciTech Connect

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.

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

2001-10-03

303

K2 yellow-band and Rb2 orange-band excimer emissions by electron-beam excitation  

Microsoft Academic Search

Amplified spontaneous emissions of the K2 yellow and Rb2 orange diffuse bands were observed from e-beam-excited mixtures of K\\/K2 or Rb\\/Rb2 vapor with argon buffer gas. The continuum spectra centered at 574 and 604 nm were attributed to triplet-triplet K2 and Rb2 23&Pgr;g?13?u+ bound-free transitions, respectively. The dissociative recombination of K3+ or Rb3+ is discussed as an efficient formation process

Da Xing; Ken-Ichi Ueda; Hiroshi Takuma

1992-01-01

304

A Comparison of Intermediate Redshift Compact Blue Galaxies: Blue Nucleated Galaxies and Compact Narrow Emission-Line Galaxies  

NASA Astrophysics Data System (ADS)

We present results of the photometric analysis of two samples of compact blue emission-line galaxies at intermediate redshift (0.1Narrow Emission-Line Galaxies (CNELGs, Koo et al. 1994) and Blue Nucleated Galaxies (BNGs, Schade et al. 1995). Using a parameter space defined by fundamental photometric properties -- surface brightness, color, image concentration, and luminosity -- we then explore the relationship of BNGs and CNELGs to local samples. Both BNGs and CNELGs are classes of faint field galaxies with very blue colors and irregular morphologies; the preponderance of evidence indicates they are undergoing a major starburst. The CNELGS are distinguished by their small sizes (half-light radii of order 0.3 arcsec), and may constitute a subclass of extremely compact BNGs. Starbursts triggered by mergers temporarily produce blue, strongly concentrated galaxies (Mihos & Hernquist 1994). Given their morphology, both CNELGs and BNGs are plausibly examples of recent mergers or interactions -- perhaps tracers of a physical process driving the evolution of blue galaxies. We explore what will happen to the BNG and CNELG samples if their star formation ceases; using galaxy evolution models to predict the reddening and fading of aging stellar populations, we infer the photometric properties of BNGs and CNELGs as they fade until the current time.

Jangren, A.; Bershady, M. A.

1997-12-01

305

Emission bands of nitrogen-implantation induced luminescent centers in ZnO crystals: Experiment and theory  

NASA Astrophysics Data System (ADS)

High quality ZnO crystals with the sharp band-edge excitonic emission and very weak green emission were implanted by nitrogen ions. An additional red emission band was observed in the as-implanted ZnO crystal and investigated as a function of temperature. By employing the underdamped multimode Brownian oscillator model for the general electron-phonon coupling system, both the original green and nitrogen-implantation induced red emission bands were theoretically reproduced at different temperatures. Excellent agreement between the theory and the experiment enables us determine the energetic positions of the pure electronic levels associated with the green and red emission bands, respectively. The determined energy level of the red emission band is in good agreement with the data obtained from the deep-level transient spectroscopy measurements.

Dai, X. M.; Xu, S. J.; Ling, C. C.; Brauer, G.; Anwand, W.; Skorupa, W.

2012-08-01

306

Band-Structure Calculation of the Electron Spin Polarization in Field Emission from Ferromagnetic Nickel.  

National Technical Information Service (NTIS)

A detailed 3d band structure of ferromagnetic Ni is incorporated into a calculation of the electron spin polarization in field emission from the (100) crystal plane. In agreement with a recent experiment of Gleich, Regenfus, and Sizmann, the calculated el...

B. A. Politzer P. H. Cutler

1972-01-01

307

Monitoring radiation belt particle precipitation - automatic detection of enhanced transient ionisation in the lower plasmasphere using subionospheric narrow band VLF signals  

NASA Astrophysics Data System (ADS)

Signals of naval VLF transmitters, propagating long distances along the Earth-ionosphere waveguide (EIWG) have been widely applied as effective tools for monitoring transient ionization at mesospheric altitudes. Perturbations in recorded amplitude and/or phase data series of stable frequency signals may refer to the effect of transient enhanced ionization in the EIWG, due to e.g. loss-cone precipitation of trapped energetic electrons (Carpenter et al., 1984, Dowden and Adams, 1990), burst of solar plasma particles (Clilverd et al., 2001). The contribution of precipitating particles are thought to be substantial in certain Sun-to-Earth energy flow processes in the upper atmosphere (Rodger et al., 2005). Narrow band VLF measuring network has been set up, developed and operated in Hungary, running in the last decade almost continuously, dedicated to monitor ionization enhancement regions along numerous transmitter-receiver paths. This setup is based on Omnipal and Ultra-MSK equipment, logging amplitude and phase data of received signals, sampled at frequencies of selected VLF transmitters. Signal trajectories, selected for recording represent proper configuration to survey transient ionization caused by energetic particles in the sub-polar region, such as effect of scattered particles of the inner radiation belt. Reprocessing of the mass archived recordings has been started using a newly developed signal processing code, detecting and classifying different sort of perturbations automatically on narrow band VLF series. Occurrence rates, daily and seasonal variation, statistics of transient ionization enhancements, their geographic distribution within the surveyed range and time period, and correlation with intense geomagnetic and/or Solar event is yielded by this analysis. References: Carpenter, D.L., Inan, U.S., Trimpi, M.L., Helliwell, R.A., and Katsufrakis, J.P.: Perturbations of subionospheric LF and MF signals due to whistler-induced electron precipitation burst, J.Geophys.Res., 89, A11, 9837-9862, 1984. Clilverd, M. A., Seppälä, A., Rodger, C.J., Thomson, N.R., Verronen, P.T., Turunen, E., Ulich, Th., Lichtenberger, J., and Steinbach, P.: Modelling polar ionospheric effects during the October-November 2003 solar proton events, Radio Sci., 41, RS2001, doi:10.1029/2005RS003290. Dowden, R.L., and Adams, C.D.D.: Lightning-induced perturbations on VLF subionospheric transmissions, J. Atmos. Terr. Phys., 52, 5, 357-363, 1990. Rodger, C.J., Clilverd, M.A., Thomson,N.R., Nunn, D., and Lichtenberger, J.: Lightning driven inner radiation belt energy deposition into the atmosphere: regional and global estimates, Ann. Geophys., 23, 3419-3430, 2005.

Steinbach, P.; Lichtenberger, J.; Ferencz, Cs.

2009-04-01

308

Intensity of Discrete VLF Emissions.  

National Technical Information Service (NTIS)

Very low frequency whistler mode noise from the magnetosphere frequently appears in the form of narrow band tones of variable frequency called discrete VLF emissions. These tones may appear spontaneously or they may be triggered by transmissions from grou...

R. A. Helliwell

1970-01-01

309

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

PubMed

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

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

2013-05-28

310

A case of gastric mucosa-associated lymphoid tissue lymphoma in which magnified endoscopy with narrow band imaging was useful in the diagnosis  

PubMed Central

Recently, we reported a case of gastric mucosa-associated lymphoid tissue (MALT) lymphoma presenting with unique vascular features. In the report, we defined the tree-like appearance (TLA) on the images of abnormal blood vessels which resembled branches from the trunk of a tree in the shiny mucosa, in which the glandular structure was lost. The 67-year-old female was diagnosed with gastric MALT lymphoma. The patient received eradication therapy for H. pylori. Conventional endoscopy revealed multiple ill-delineated brownish depressions in the stomach and cobblestone-like mucosa was observed at the greater curvature to the posterior wall of the upper gastric body 7 mo after successful eradication. Unsuccessful treatment of gastric MALT lymphoma was suspected on conventional endoscopy. Conventional endoscopic observations found focal depressions and cobblestone-like appearance, and these lesions were subsequently observed using magnified endoscopy combined with narrow band imaging to identify abnormal vessels presenting with a TLA within the lesions. Ten biopsies were taken from the area where abnormal vessels were present within these lesions. Ten biopsies were also taken from the lesions without abnormal vessels as a control. A total of 20 biopsy samples were evaluated to determine whether the diagnosis of MALT lymphoma could be obtained histologically from each sample. A positive diagnosis was obtained in 8/10 TLA (+) sites and in 2/10 TLA(-) sites. Target biopsies of the site with abnormal blood vessels can potentially improve diagnostic accuracy of gastric MALT lymphoma.

Nonaka, Kouichi; Ishikawa, Keiko; Arai, Shin; Nakao, Masamitsu; Shimizu, Michio; Sakurai, Takaki; Nagata, Koji; Nishimura, Makoto; Togawa, Osamu; Ochiai, Yasutoshi; Sasaki, Yutaka; Kita, Hiroto

2012-01-01

311

Study on Surface Acoustic Wave Characteristics of SiO2/Interdigital-Transducer/ZnO/Diamond Structure and Fabrication of 2.5 GHz Narrow Band Filter  

NASA Astrophysics Data System (ADS)

Surface acoustic wave (SAW) characteristics of the SiO2/interdigital-transducer(IDT)/ZnO/diamond structure were studied theoretically and experimentally. It was found that the 2nd mode in this structure can provide a zero temperature coefficient of frequency (TCF) as well as high velocity of 10,000 m/s and a large electromechanical coupling coefficient of 1.4%. Utilizing this wave, a 2.5 GHz narrow-band SAW filter was successfully fabricated with IDTs of 0.9 µm finger width, which resulted in superior characteristics for a retiming filter with a small insertion loss of 6.7 dB, Q value of 660 and small frequency deviation of 100 ppm in the temperature range from -40 to 85°C. The insertion loss is smaller than any other retiming filters which have ever been reported with quartz, a conventional SAW material, and also the frequency deviation with temperature is smaller than that in the case of ST-cut quartz.

Nakahata, Hideaki; Kitabayashi, Hiroyuki; Uemura, Tomoki; Hachigo, Akihiro; Higaki, Kenjiro; Fujii, Satoshi; Seki, Yuichiro; Yoshida, Kentaro; Shikata, Shin-ichi

1998-05-01

312

Feeding at a high pitch: source parameters of narrow band, high-frequency clicks from echolocating off-shore hourglass dolphins and coastal Hector's dolphins.  

PubMed

Toothed whales depend on echolocation for orientation and prey localization, and source parameters of echolocation clicks from free-ranging animals therefore convey valuable information about the acoustic physiology and behavioral ecology of the recorded species. Recordings of wild hourglass (Lagenorhynchus cruciger) and Hector's dolphins (Cephalorhynchus hectori) were made in the Drake Passage (between Tierra del Fuego and the Antarctic Peninsular) and Banks Peninsular (Akaroa Harbour, New Zealand) with a four element hydrophone array. Analysis of source parameters shows that both species produce narrow band high-frequency (NBHF) echolocation clicks. Coastal Hector's dolphins produce clicks with a mean peak frequency of 129 kHz, 3 dB bandwidth of 20 kHz, 57 micros, 10 dB duration, and mean apparent source level (ASL) of 177 dB re 1 microPa(p.-p.). The oceanic hourglass dolphins produce clicks with mean peak frequency of 126 kHz, 3 dB bandwidth of 8 kHz, 116 micros, 10 dB duration, and a mean estimated ASL of 197 dB re 1 microPa(p.-p.). Thus, hourglass dolphins apparently produce clicks of higher source level, which should allow them to detect prey at more than twice the distance compared to Hector's dolphins. The observed source parameter differences within these two NBHF species may be an adaptation to a coastal cluttered environment versus a deep water, pelagic habitat. PMID:19275335

Kyhn, Line A; Tougaard, J; Jensen, F; Wahlberg, M; Stone, G; Yoshinaga, A; Beedholm, K; Madsen, P T

2009-03-01

313

On-orbit radiometric stability assessment of MODIS thermal emissive bands with lunar observation  

NASA Astrophysics Data System (ADS)

The MODIS thermal emissive bands (TEB) are radiometrically calibrated on-orbit on a scan-by-scan basis, with reference to an aboard blackbody operated at 290 K for Terra MODIS and at 285 K for Aqua MODIS. The quality of the calibration can be evaluated with independent thermal sources at other temperatures. As a spectrally, spatially and radiometrically stable source, the Moon has become more important to the on-orbit calibration of space-borne spectral sensors that have regular lunar observation capability. MODIS is scheduled to observe the Moon on a nearly monthly basis at approximately the same lunar phase angle through its space view port. In this paper, the long-term stability of MODIS TEB radiometric calibration is assessed through the multi-year trends of the brightness temperatures (BT) of the lunar surface retrieved from the scheduled lunar observation. The highest lunar surface temperature is approximately 390 K, higher than the saturation temperatures of most TEB. For the non-saturated bands, the trending is based on the BT of the hottest area of the Moon. For the partially saturated bands, the trending is based on the BT difference of the unsaturated matching pixels between the band and a non-saturated reference band, given the fact that all MODIS bands are spatially registered. Overall, the trends have been stable throughout MODIS lifetime. The results also prove that the Moon can be used as a source to monitor the stability of the thermal bands.

Wang, Zhipeng; Xiong, Xiaoxiong (Jack); Chen, Hongda; Madhavan, Sriharsha

2013-09-01

314

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

Microsoft Academic Search

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

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

315

Total absorptivities and emissivities of particulate coal ash from spectral band emissivity measurements  

Microsoft Academic Search

Previous measurements of the spectral emissivity of coal ashes are converted to total absorptivities and emissivities. Below the temperature at which ash sinters, the total absorptivity of an ash layer-which is necessary for the estimation of radiative transfer in furnances-is shown to depend on both the source (flame) temperature and the ash temperature. Synthetic mixtures of the oxides AlâOâ, SiOâ,

T. F. Wall; M. B. Becker

1984-01-01

316

VIIRS thermal emissive bands on-orbit calibration coefficient performance using vicarious calibration results  

NASA Astrophysics Data System (ADS)

The Visible Infrared Imager Radiometer Suite (VIIRS), a primary sensor on-board the Suomi-National Polar-orbiting Partnership (SNPP) spacecraft, was launched October 28, 2011. It has 22 bands: 7 thermal emissive bands (TEBs), 14 reflective solar bands (RSBs) and a Day Night Band (DNB). The TEBs cover the spectral wavelengths between 3.7 to 12 ?m and have two 371 m and five 742 m spatial resolution bands. A VIIRS Key Performance Parameter (KPP) is the sea surface temperature (SST) which uses bands M12 (3.7 ?m), M15 (10.8 ?m) and M16's (12.0 ?m) calibrated Science Data Records (SDRs). The TEB SDRs rely on pre-launch calibration coefficients used in a quadratic algorithm to convert the detector's response to calibrated radiance. This paper will evaluate the performance of these prelaunch calibration coefficients using vicarious calibration information from the Cross-track Infrared Sounder (CrIS) also onboard the SNPP spacecraft and the Infrared Atmospheric Sounding Interferometer (IASI) on-board the Meteorological Operational (MetOp) satellite. Changes to the pre-launch calibration coefficients' offset term c0 to improve the SDR's performance at cold scene temperatures will also be discussed.

Moyer, D.; Moeller, C.; De Luccia, F.

2013-09-01

317

Collision-induced emission in the fundamental vibration-rotation band of H sub 2  

SciTech Connect

Measurements of collision-induced emission in the fundamental vibration-rotation band of hydrogen are presented for argon, xenon, and neon collision partners. These absolute, spectrally resolved infrared measurements were performed at high densities behind reflected shock waves over the temperature range of 900--3400 K. The emission was found to be dominated by {ital Q}-branch transitions at high temperature due primarily to the dipole moment induced by the overlap between the electron clouds of the collision pair. The strength of this interaction was evaluated from the data and compared with similar evaluations determined from low-temperature absorption studies.

Caledonia, G.E.; Krech, R.H. (Physical Sciences Inc., Andover, Massachusetts 01810 (USA)); Wilkerson, T.D. (Institute of Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (USA)); Taylor, R.L. (CVD Inc., Woburn, Massachusetts 08101 (USA)); Birnbaum, G. (National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (USA))

1991-06-01

318

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

NASA Astrophysics Data System (ADS)

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. Acoustic emission sensors attached to an accelerator structure can detect both nominal and breakdown RF pulses. 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.

Frisch, J.; Nelson, J.; Le Pimpec, F.; Jobe, K.; McCormick, D.

2002-08-01

319

Fourier transform emission spectroscopy of some new bands of ReN  

NASA Astrophysics Data System (ADS)

The emission spectrum of ReN has been reinvestigated in the visible region using a Fourier transform spectrometer. Two new bands have been identified with band origins near 22 110 and 22 224 cm-1. These bands have a common lower state and have been assigned as the 0+ A1 and 0- A1 transitions. After rotational analysis it was noted that the new 0+ A1 transition also has its upper state in common with the upper state of the [24.7]0+ X0+ transition reported previously [W.J. Balfour, J. Cao, C.X.W. Qian, S.J. Rixon, J. Mol. Spectrosc. 183 (1997) 113 118.]. This observation provides T00 = 2616.26 cm-1 for the A1 state. It is likely that the A1 and X0+ states are two spin components of the 3?- ground state.

Ram, R. S.; Bernath, P. F.; Balfour, W. J.

2007-12-01

320

Correlation between Magnifying Narrow-band Imaging Endoscopy Results and Organoid Differentiation Indicated by Cancer Cell Differentiation and its Distribution in Depressed- Type Early Gastric Carcinoma.  

PubMed

Background: A close association between patterns identified by magnifying narrow-band imaging (M-NBI) and histological type has been described. M-NBI patterns were also recently reported to be related to the mucin phenotype; however, detials remain unclear. Materials and Methods: We investigated the cellular differentiation of gastric cancer lesions, along with their mucosal distribution observed by M-NBI. Ninety-seven depressed-type early gastric cancer lesions (74 differentiated and 23 undifferentiated adenocarcinomas) were visualized by M-NBI. Findings were divided into 4 patterns based on abnormal microvascular architecture: a chain loop pattern (CLP), a fine network pattern (FNP), a corkscrew pattern (CSP), and an unclassified pattern. Mucin phenotypes were judged as gastric (G-type), intestinal (I-type), mixed gastric and intestinal (M-type), and null (N-type) based on 4 markers (MAC5AC, MUC6, MUC2, and CD10). The relationship of each pattern of microvascular architecture with organoid differentiation indicated by cancer cell differentiation and its distribution in each histological type of early gastric cancer was investigated. Results: All CLP and FNP lesions were differentiated. The cancer cell distribution showed organoid differentiation in 84.2% (16/19) and 61.1% (22/36) of the two types of lesions, respectively, and there was a significant difference from the unclassified pattern with organoid differentiation (p<0.001). Almost all (94.7%; 18/19) CSP lesions were undifferentiated, and organoid differentiation was observed in 72.2% (13/18). There was a significant difference from the unclassified pattern with organoid differentiation (p<0.05). Conclusions: Cellular differentiation and distribution are associated with microvascular architecture observed by M-NBI. PMID:23803029

Tatematsu, Hidezumi; Miyahara, Ryoji; Shimoyama, Yoshie; Funasaka, Kohei; Ohno, Eizaburou; Nakamura, Masanao; Kawashima, Hiroki; Itoh, Akihiro; Ohmiya, Naoki; Hirooka, Yoshiki; Watanabe, Osamu; Maeda, Osamu; Ando, Takafumi; Goto, Hidemi

2013-01-01

321

COMPARATIVE THERAPEUTIC EVALUATION OF DIFFERENT TOPICALS AND NARROW BAND ULTRAVIOLET B THERAPY COMBINED WITH SYSTEMIC METHOTREXATE IN THE TREATMENT OF PALMOPLANTAR PSORIASIS  

PubMed Central

Background: The incidence of uncomplicated psoriasis is 1–3% in the general population. The involvement of palm and sole is seen in 7–14.5% of cases. There are different topicals and systemic therapies available for treating the case of psoriasis but none is satisfactory for longer duration. Aim: The study involved the comparative therapeutic evaluation of the different topical regimens and narrow band ultraviolet B (NB-UVB) therapy in combination with systemic methotrexate. Materials and Methods: The study was held in out-patient department of Skin, VD and Leprosy of B.R.D. Medical College, Gorakhpur, from July 2007 to December 2008. The group included 98 new cases of palmoplantar psoriasis. These cases were divided into eight groups according to the eight regimens involved in the study. The severity of psoriasis was assessed by the ESIF (erythema, scaling, induration and fissuring) score. Results: The study showed that all the regimens had significant response rates. The combination of NB-UVB with systemic methotrexate had maximum response rate (64.85±4.52%) that was statistically significant (paired “t” at 16d.f. = 33.329, P<0.001) with minimum number of recurrences after stopping the treatment. The combination of halobetasol ointment with systemic methotrexate also had significant response rate (paired “t” at 19d.f. = 13.5183, P<0.001) but had maximum number of cases with recurrence (70%) after stopping the treatment. Conclusion: These results suggest that the combination of every regimen with systemic methotrexate resulted in an early and a good improvement in the quality of life of patients suffering from psoriasis. It also shows that NB-UVB in combination with systemic methotrexate is more efficacious and has minimum recurrence rate and side effects in the treatment of palmoplantar psoriasis.

Gupta, Sunil K; Singh, K K; Lalit, Mohan

2011-01-01

322

Laboratory Measurement of the CO Cameron Bands and Visible Emissions Following VUV Photodissociation of CO{_2}  

Microsoft Academic Search

The CO(a^{3}Pi-X^{1}Sigma^{+}) Cameron bands are one of the most important emission features in the UV dayglow of the CO{_2} planets, as demonstrated in the case of Mars by the measurements performed by Mariner and Mars Express missions. One of the mechanisms to produce electronically excited CO(a^{3}Pi) is photodissociation of CO{_2} at wavelengths shorter than 108 nm. At wavelengths below 100

K. S. Kalogerakis; C. Romanescu; T. G. Slanger; L. C. Lee; M. Ahmed; K. R. Wilson

2009-01-01

323

Helium microwave induced plasma atomic emission detection for liquid chromatography utilizing a moving band interface  

Microsoft Academic Search

A moving band interface is used to separate HPLC solvent from analyte before introduction into a microwave-induced plasma atomic emission detector. Spectral scans indicate that all detectable solvent is removed prior to analyte introduction. Analyte memory effects are not detectable. Chlorine element selective detection limits are 140,410, 220, and 770 pg\\/s for 9-chlorofluorene, p-chlorobiphenyl, 4-chlorobenzophenone, and [alpha],[alpha]'-dichloro-o-xylene, respectively. If the

Peter B. Mason; Liming. Zhang; Jon W. Carnahan; Randall E. Winans

1993-01-01

324

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

PubMed

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. PMID:19256621

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

2009-02-28

325

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

NASA Astrophysics Data System (ADS)

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.

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

2009-02-01

326

Low energy emission bands in a small molecular fluorene derivative for organic light-emitting diodes  

NASA Astrophysics Data System (ADS)

6,6'-(9H-fluoren-9,9-diyl)bis(2,3-bis(9,9-dihexyl-9H-fluoren-2-yl)quinoxaline) (BFLBBFLYQ) was a novel small molecular fluorene material with fluorescence maxima at 450 nm in spin cast films. Compared to spin cast films, BFLBBFLYQ vacuum evaporated deposition films exhibited different photo-physical properties. The low energy emission bands from 530 to 570 nm were observed from the electroluminescence (EL) and photoluminescence (PL) spectra of BFLBBFLYQ films evaporated deposition in ultrahigh vacuum circumstance, and the origin of these emission features were investigated and discussed. Also, the emissive properties of BFLBBFLYQ spin cast films upon thermal annealing and under UV irradiation in air were characterized for the effect of thermal oxidization and photo-oxidization.

Lou, S. L.; Yu, H. S.; Ma, W. M.; Jiang, Y.; Zhang, Q.

2008-11-01

327

Surface-plasmon enhancement of band gap emission from ZnCdO thin films by gold particles  

NASA Astrophysics Data System (ADS)

We present our study of the dependence of surface plasmon (SP) coupled band gap emission and defect emission on the sputtering time of gold particles on ZnCdO films. Eightfold enhancement of the band gap emission from ZnCdO thin films coated with Au particles is observed, while the defect emission is completely suppressed. The remarkable enhancement of the band gap emission is mainly attributed to the coupling between excitons in ZnCdO films and the SP of Au particles. While the suppression of the defect emission may be ascribed to a combined effect of the reduction in surface defects and the charge transfer from defect level to the Au Fermi level.

Yang, W. F.; Chen, R.; Liu, B.; Gurzadyan, G. G.; Wong, L. M.; Wang, S. J.; Sun, H. D.

2010-08-01

328

Surface-plasmon enhancement of band gap emission from ZnCdO thin films by gold particles  

SciTech Connect

We present our study of the dependence of surface plasmon (SP) coupled band gap emission and defect emission on the sputtering time of gold particles on ZnCdO films. Eightfold enhancement of the band gap emission from ZnCdO thin films coated with Au particles is observed, while the defect emission is completely suppressed. The remarkable enhancement of the band gap emission is mainly attributed to the coupling between excitons in ZnCdO films and the SP of Au particles. While the suppression of the defect emission may be ascribed to a combined effect of the reduction in surface defects and the charge transfer from defect level to the Au Fermi level.

Yang, W. F.; Chen, R.; Liu, B.; Gurzadyan, G. G.; Sun, H. D. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Wong, L. M.; Wang, S. J. [Institute of Materials Research and Engineering, Singapore 117602 (Singapore)

2010-08-09

329

New Optical Emissions in the Terrestrial Nightglow: The O2(c-b) Bands  

NASA Astrophysics Data System (ADS)

Sky spectra from the Keck I and II telescopes in the 380-450 nm region have revealed the presence of a new O2 band system, the transition between the c1?u- b1?g+ states. There is only a Q-branch associated with the transition and the unusual symmetry favors emission from high rotational le vels. Radiation from c(v = 9,10) is particularly pronounced, but O2(c) population is seen over the range v = 5-11. The sparse individual lines of the 9-1 c-b band are as bright as any Herzberg I or Chamberlain band line at wavelengths longer than 365 nm. We have not yet seen lines in the c-X Herzberg II system in the present data set at wavelengths greater than 337 nm. The probable explanation for the c-b transition being evident while the c-X transition is not is that the c-b emission is concentrated in 1/4 as many lines, and the strongest c-X bands are at shorter wavelengths, inaccessible from the ground. We presently estimate an emission intensity of 30 R for the c-b system. As the term energies for both states are accurately known, the lines can be used for precise calibration of aeronomical and astronomical spectra, as well as for investigations on the c1?u- state. Loss rate coefficients for the c(v = 8-11) levels are currently being determined in the laboratory for the temperature range relevant to the terrestrial upper atmosphere[1]. [1] G. Amaral, G. B. Bressler, E. S. Hwang, K. Kalogerakis, A. Totth, and R. A. Copeland (in preparation); R. A. Copeland, K. Knutsen, M. E. Onishi, and T. Yalcin, J. Chem. Phys. 105, 10340 (1994). This work was supported by a grant from the NSF CEDAR program.

Slanger, T. G.; Cosby, P. C.; Huestis, D. L.

2002-05-01

330

Narrow-band filter for the frequency range of 1.9 GHz using double-sided YBCO films on 10-mm-square and 20-mm-square LaAlO3 substrates  

Microsoft Academic Search

Narrow-band microstrip hairpin-type filters are designed for wireless-communication applications. We have fabricated the high-Tc superconducting filters by patterning YBa2Cu3Oy (YBCO) films deposited on 10-mm-square and 20-mm-square, 0.6-mm-thick LaAlO3 substrates. The form of hairpin-resonator band-pass filter can be thought of as an alternative version of parallel-couple-resonator filter, except that the open-circuited ends of the resonator are folded back. Our 3-pole 10-mm-square

L. M. Wang; Mao-Yuan Horng; Chen-Chung Liu; Jyh-Haur Tsao; H. H. Sung; H. C. Yang; H. E. Horng

2003-01-01

331

Examining the Broadband Emission Spectrum of WASP-19b: A New z-band Eclipse Detection  

NASA Astrophysics Data System (ADS)

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 ?m in size are unlikely to be present in WASP-19b.

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

2013-09-01

332

Study of local time dependence of the attenuation band associated to the Jovian hectometric emission  

NASA Astrophysics Data System (ADS)

We study the phenomenological spectral features of the Jovian hectometric (HOM) emission recorded during the Jupiter flyby by the RPWS experiment onboard the Cassini spacecraft. The capability of this experiment allowed a frequency coverage from a few hertz to 16 MHz with a large dynamic range of about 80 dB. HOM emission was regularly observed several weeks before and after the closest approach of the planet. We analyze the Jovian radio dynamic spectra recorded from the end of November 2000 to the second week of January 2001. During this period, the spacecraft approached Jupiter from a distance of more than 500 RJ to 137 RJ (closest approach on December 30, 2010) and back to about 250 RJ. We attempt in this study to investigate the local time (LT) dependence of the attenuation band due to refraction effects caused by the presence of the Io plasma torus. We analyze the spectral features of the attenuation band taking into consideration three local time intervals [10.0 LT, 13.2 LT], [13.6 LT, 16.5 LT], and [16.7 LT, 20 LT]. A statistical study leads us to characterize the spectral features of the attenuation band principally on the day-side and the late afternoon sector of the planet. This will allow us to discuss the LT variation of the electronic density of the Io plasma torus versus the central meridian longitude (CML) and the Jovian magnetic latitude.

Boudjada, M. Y.; Galopeau, P. H. M.

2011-10-01

333

Global surface reflectivity study relating 340 nm SBUV narrow band LER to 412 nm SeaWiFS broadband LER using OMI spectrally resolved data  

NASA Astrophysics Data System (ADS)

The purpose of this study is to combine the SeaWiFS 412 nm Lambert Equivalent Reflectivity (LER) record (1998 - 2009) with the 30-year 340 nm LER record of SBUV/TOMS (1979 - 2009) for detecting global changes in cloud and aerosol cover. OMI spectrally resolved (0.6 nm) data is used to simulate the conversion between SeaWiFS 412±10nm LER and 340±1nm LER. The issues in this investigation include wavelength dependence (340 vs 412 nm), LER difference between narrow band (SBUV) and broadband (SeaWiFS), and instrument/calibration bias between two OMI detectors (UV2 for 340 nm and VIS for 412 nm). The data set analyzed in this discussion is based on 5 degree zonal averages. The results show that (1) the spectral difference in LER(412±1nm) - LER(350±1nm) is about 0.2RU (1RU = 0.01 reflectivity) in the equatorial region, up to 1.0 RU as the latitude increases to 60N/60S, but peaks at 1.2RU near 20N to 30N. The difference also strongly depends on surface type (land vs ocean), and has seasonal variations (especially at high latitudes); (2) the bandwidth induced difference of LER at 412 nm has strong latitude dependence as well, starting from 1.0RU (LER(412±1nm)- LER(412±10nm)) in 25N-25S and ending at 3.0RU in 60N or 60S. The difference increases almost linearly with LER; (3) the detector bias is overall pretty small, about 0.6RU (UV2 - VIS) with variations in 1.0 - 1.5RU, increasing with LER. Combining the results from all three steps, we derive a correction coefficient to relate 340 nm SBUV-2 LER with the 412 nm SeaWiFS LER. This coefficient is about 1.5RU between 40N and 40S and up to 2.5RU beyond this latitude region. However, this coefficient strongly depends on surface type. For example, over desert land, it could be as low as 0.2RU, whereas over clouds/snow/ice areas, it could be as high as 3.0RU. In addition, to match the SBUV 340 nm LER, we also need to consider the footprint difference between SBUV and SeaWiFS, as well as solar zenith angle effects on the relationship.

Qin, W.; Herman, J. R.; Jaross, G. R.; Labow, G. J.

2009-12-01

334

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

335

Effect of oxide band structure on the emission process of excited atoms under ion bombardment  

NASA Astrophysics Data System (ADS)

Ion-photon emission (IPE) was investigated under Ar+ ion bombardment of magnesium aluminate spinel crystals of different compositions MgO.nAl2O3 (n=1.0; 2.5) and, for comparison Al-metal target. For all targets the only emission of metal excited particles was observed, which leads to lines of Al I, Al II, Al III, Mg I and Mg II spectra. It was revealed that quantum yield of the IPE of different lines were equal in the range of values 10-4-10-7 photon/ion and increases in 5-7 times of that originated from decay of atomic excited states with Eex<=4.83 eV for oxides to compare with metal. The main criteria, which determines the conservation of excitation in flying-off atoms or ions is relation between the band structure of target and energy level of corresponding exited state of emitting particles. Analysis of obtained data allows us to estimate the width of conduction band (?) in spinel: 0.995eV<=?<=1.16 eV. There was suggested the new approach for description of energy distribution of emission of knocked out excited particles. The best agreement of calculated data with experimental ones was obtained when the contribution of both the cascade collisions and surface recoil processes of primary ions in solids are included to generate flying-off excited particles.

Bobkov, V. V.; Gokov, S. P.; Gritsyna, V. V.; Gritsyna, V. T.; Shevchenko, D. I.

2004-06-01

336

The effects of reorientation on the emission properties of a photonic band edge liquid crystal laser  

NASA Astrophysics Data System (ADS)

The effect of altering the excitation rate on the emission energy of a photonic band edge liquid crystal laser has been investigated. The results showed that for excitation energies greater than 18 µJ/pulse, an increase in the excitation rate from 1 to 20 Hz caused a reduction in the total emission energy of the photonic band edge liquid crystal laser of up to 90%. In order to establish the cause of this reduction several factors were considered: dye bleaching, thermal/density effects and director-axis reorientation (either by virtue of a light-induced torque or other effects such as a flow-induced orientational decay). Although some dye bleaching was observed, the main factor responsible for the reduction in the overall emission efficiency was found to be nonlinear changes in the director-axis reorientation. Furthermore, our results suggest that the director-axis reorientation is the result of an optical torque, enhanced by the presence of the dye, which for a chiral nematic liquid crystal results in a dilation of the helical pitch.

Morris, S. M.; Ford, A. D.; Pivnenko, M. N.; Coles, H. J.

2005-05-01

337

Impact of rain interception by vegetation and mulch on the L-band emission of natural grass  

Microsoft Academic Search

This paper explores the effect of rain intercepted by vegetation and mulch on the L-band emission of natural grass. The study is based on radiometric, meteorological, and biophysical measurements obtained during the SMOSREX Experiment (Toulouse, France). Several approaches were followed to evaluate interception effects. Firstly, the analysis of microwave brightness temperature (TB) measurements at L-band indicated that interception increases vegetation

Kauzar Saleh; Jean-Pierre Wigneron; Patricia de Rosnay; Jean-Christophe Calvet; Maria José Escorihuela; Yann Kerr; Philippe Waldteufel

2006-01-01

338

Entanglement of a two-level atom and its spontaneous emission near the edge of a photonic band gap  

Microsoft Academic Search

The entanglement of a two-level atom and its radiation field near the edge of a photonic band gap is studied by using the quantum entropy. Unlike the free space case, there is a steady-state entanglement between the atom and its spontaneous emission field even when the atomic transition frequency lies outside the band gap. Moreover, the degree of entanglement, which

S. Roshan Entezar

2009-01-01

339

Emission model of AIBs: the case of the 11.2 ?m band  

NASA Astrophysics Data System (ADS)

Amongst the Aromatic Infrared Bands (AIBs), the strong 11.2 ?m feature has a very distinctive shape with a steep blue side and a long red tail. Making use of these characteristics, modelling of this feature is taken as the starting point in assessing classes of molecules as carriers of all of the AIBs. Quantum chemical calculations on a set of large Polycyclic Aromatic Hydrocarbons (PAHs) are carried out using DFT. The infrared transitions obtained are then used to model the astronomical emission spectrum including the 11.2 ?m band. Conclusions are drawn in terms of goodness of the fit for the 11.2 ?m feature and for the overall 3-20 ?m AIB spectrum.

Candian, A.; Sarre, P.

2011-05-01

340

[Research on the emission spectrum of NO molecule's ?-band system by corona discharge].  

PubMed

The optical emission spectrum of the gamma-band system of NO molecule, A2 sigma+ --> X2 pi(r), has been analyzed and calculated based on the energy structure of NO molecule' doublet states. By employing the theory of diatomic molecular Spectra, some key parameters of equations for the radiative transition intensity were evaluated theoretically, including the potentials of the doublet states of NO molecule's upper and lower energy levels, the electronic transition moments calculated by using r-centroid approximation method, and the Einstein coefficient of different vibrational and rotational levels. The simulated spectrum of the gamma-band system was calculated as a function of different vibrational and rotational temperature. Compared to the theoretical spectroscopy, the measured results were achieved from corona discharge experiments of NO and N2. The vibrational and rotational temperatures were determined approximately by fitting the measured spectral intensities with the calculated ones. PMID:22827043

Zhai, Xiao-dong; Ding, Yan-jun; Peng, Zhi-min; Luo, Rui

2012-05-01

341

NPP Visible/Infrared Imaging Radiometer Suite (VIIRS) radiometric calibration emissive bands: tested performance  

NASA Astrophysics Data System (ADS)

The Visible/Infrared Imaging Radiometer Suite (VIIRS) collects radiometric and imagery data in 22 spectral bands within the visible and infrared spectrum ranging from 0.4 to 12.5 ?m. This paper describes the radiometric uncertainty requirements for the 7 VIIRS thermal emissive bands and the calibration methodology employed to meet these requirements, including the on-board calibration subsystems and the retrieval algorithm for generating calibrated radiance from instrument data. The instrument characteristics contributing to uncertainties in retrieved radiance are presented based on results from the recently completed pre-launch test program. The final roll-up of these uncertainties relative to the absolute radiometric requirements are shown, and compared against the results obtained from the radiance retrieval algorithm exercised during thermal-vacuum testing for a NIST traceable Blackbody Calibration Source.

Johnson, Eric; Galang, Karen; Ranshaw, Courtney; Robinson, Brendan

2010-08-01

342

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

NASA Astrophysics Data System (ADS)

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.

Soliman, C.; Hussein, M. A.

2004-04-01

343

HNSi - nu(1) emission band by high resolution Fourier transform spectroscopy  

NASA Astrophysics Data System (ADS)

The emission spectrum of the fundamental vibration-rotation nu(1) band (NH stretch) of iminosilicon HNSi has been observed near 2.7 microns by high-resolution Fourier transform spectroscopy from a mixture of N2 + SiH4 excited in a radio frequency discharge. This is the first spectroscopic observation of this molecule in the gas phase. Molecular constants sigma, B, D, and H are reported. Calculated microwave transitions which should be helpful for the investigation and the possible identification of HNSi in astrophysical sources are also given.

Elhanine, M.; Farrenq, R.; Guelachvili, G.

1991-02-01

344

Simultaneous measurements of the OH(8,3) band OI 5577 A airglow emissions  

NASA Astrophysics Data System (ADS)

Simultaneous measurements of the night airglow OH(8,3) band and OI 4477 A Correlations between the nocturnal variations of these emissions and the OH rotational temperature are presented. It was found that OH(8,3) is correlated with the rotational temperature but at a time lag of about 1 hour. The variations of 5577 A lead the OH(8,3) by about 2 to 3 hours. The rotational temperature co-varies with 5577A, rather than with OH(8,3) and there is no significant time lag. Based on this correlation study, the nocturnal variations of the two emissions are explained by the atmospheric density perturbation caused by solar tides and internal gravity waves.

Takahashi, H.; Sahai, Y.; Clemesha, B. R.; Simonich, D. M.; Batista, P. P.; Teixeira, N. R.

1977-08-01

345

Simultaneous measurements of the OH/8,3/ band and OI 5577 A airglow emissions  

NASA Astrophysics Data System (ADS)

Simultaneous measurements of the OH(8,3) band and OI 5577 A during June-August 1976 have shown correlations both between the nocturnal variations of these emissions and with the OH rotational temperature. A time lag of one hour is found between OH(8,3) and the rotational temperature, while the variations of 5577 A lead the OH(8,3) by about two to three hours. It is also determined that the rotational temperature co-varies with 5577 A rather than OH(8,3), and that there is no significant time lag. These correlations allow the nocturnal variations of the two emissions to be explained by atmospheric density perturbations due to solar tides and internal gravity waves.

Takahashi, H.; Sahai, Y.; Clemesha, B. R.; Simonich, D. M.; Batista, P. P.; Teixeira, N. R.

1981-09-01

346

Field-Induced Insulator to Semimetal Transition and Field Electron Emission of Nanorods of Semiconductors of Wide Energy Band Gaps  

Microsoft Academic Search

Significant field emission is found theoretically possible from nanorods of semiconductors of wide energy band gaps. If the nanorod has a thin surface layer containing a large number of localized states, a part of nanorod can exhibit an insulator-to-semimetal transition under high enough fields of direction parallel to its axis, so that field emission occurs at the apex of the

Zhibing Li; Weiliang Wang; Shaozhi Deng; Ningsheng Xu; Guiyang Huang

2005-01-01

347

Evaluation of Terra and Aqua MODIS thermal emissive band calibration consistency  

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

348

Improved NLTE model for the IR CO2 bands emission in the Martian atmosphere  

NASA Astrophysics Data System (ADS)

Radiative transfer in the IR ro-vibrational bands of CO 2 is an important factor in establishing the structural and dynamical properties of the entire Martian atmosphere Also the emissions in some of the CO 2 bands are used for remote sensing of the atmosphere during spacecraft missions to Mars So these reasons require more sophisticated models of populations of the excited vibrational states of the CO 2 molecules A model for solving the problem of radiative transfer in the CO 2 bands under non-local thermodynamic equilibrium NLTE in the Martian atmosphere has been further developed In comparison to the previous version of our model 1 the main improvements are as follows 1 Radiative transfer in the near-infrared CO 2 bands within the 5 div 1 02 mu m spectral range was considered with exact treatment of overlapping over frequency of ro-vibrational lines 2 The IR spectral line radiation absorption due to dust aerosols whose optical depth can be significant during Martian global dust storms GST was taken into account for the first time 3 The set of the V-V and V-T processes of CO 2 molecular vibration energy exchange during collisions between different species of the Martian atmosphere has been renewed as well as the rate constants of these processes The NLTE populations of more than 300 excited states of 7 isotopes of CO 2 with vibrational energy up to 9500 cm -1 are calculated using the Accelerated Lambda Iteration technique with relative error not worse than 10 -5 The

Ogibalov, V.

349

The broad-band spectrum of the persistent emission from SGR 1806-20  

NASA Astrophysics Data System (ADS)

We present the results of an analysis of the quiescent X-ray emission from the Soft Gamma-Ray Repeater SGR 1806-20, taken during an INTEGRAL ultra-deep survey of the Galactic center region in Aug.-Sep. 2003. The total effective exposure time spent on the source by the IBIS telescope during these observations was 1.6 million seconds. Combining the INTEGRAL results with results from the XMM-Newton observatory, we present the broad band (1-200 keV) spectrum of the quiescent emission from this source. This is the first spectrum of the persistent emission from an SGR in the broad energy range up to 200 keV. The spectrum of the source is very hard and has a power law shape (?=1.6±0.1) without any trace of a high energy cutoff up to ~160 keV. No strong cyclotron line was detected in the persistent spectrum. The luminosity of SGR 1806-20 in this range (1-200 keV) was ˜ 3.6×1036 erg s-1 for an assumed distance of 15 kpc. We show that weak undetected bursts should not contribute significantly to the quiescent emission. During our next observations in August 2004 the source went into an active phase and its average flux between powerful bursts was 2-3 times higher than in 2003. During Aug.-Sep. 2003, two other SGR candidates, SGR 1801-23 and SGR 1808-20, were in the field of view. Neither persistent hard X-ray emission nor bursts were detected from them. The upper limit on the persistent flux from each of them in the energy band 18-100 keV is about 4×10-11 erg s-1 cm-2. Based on observations with INTEGRAL, an ESA project with instruments and science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), Czech Republic and Poland, and with the participation of Russia and the USA.

Molkov, S.; Hurley, K.; Sunyaev, R.; Shtykovsky, P.; Revnivtsev, M.; Kouveliotou, C.

2005-04-01

350

Spatial distribution and variation of narrow L-shell bands in the plasmasphere supporting field-aligned propagating modes as observed by the RPI/IMAGE satellite  

NASA Astrophysics Data System (ADS)

Field-aligned propagating (FAP) modes have been a regular characteristic of the RPI/IMAGE plasmagrams from the beginning of the experiment. LF/MF (in the range of 3 kHz to 3 MHz) transmitted radio signals from the satellite propagate in the magnetic meridian plane along the magnetic field line passing through the satellite position to both the northern and southern hemispheres where they reflect at a level that depends on the sounding frequency. This analysis has shown that these hemispherical reflections occur on about 20% of the plasmagrams while the IMAGE satellite is between L = 2.5 and L = 4.5. Occurrences of these FAP plasmagrams were consistently organized into two L-shell bands. The first band was found at L = 3.2+/- 0.2 moving in and out slowly over a period of a few days. This band, with a width of DL >> 0.2, is always present. The second observed band also supports hemispherical propagation and was found at higher L-shells, ranging from L = 3.5 under quiet magnetic conditions, moving to L = 4.0 as the level of magnetic activity increases. During high magnetic activity conditions this outer band disappears. When RPI/IMAGE passed through the inner band the probability of the appearance of FAP modes was 98% while for the outer band this percentage drops to 91%. Analyzing 5 months of data using an RPI sounding program that makes a new plasmagram every 3 minutes as the satellite traverses the plasmasphere has lead to a comprehensive description of these bands that can be mapped down to the mid-latitude trough region. Comparison is made between the plasmaspause location and the tail region as determined using other sensors with respect to the position of the two bands under changing magnetic conditions.

Sales, G.; Reinisch, B. W.; Song, P.; Huang, X.; Galkin, I.; Gallagher, D. L.

2002-12-01

351

Geomagnetic conjugacy of 30-kHz band auroral hiss emissions observed at L = 6. 1  

SciTech Connect

Statistical characteristics of auroral hiss emissions in the 30-kHz band were examined using the data observed simultaneously at the Syowa-Husafell conjugate pair of stations during the period of September-November 1983. The occurrence probabilities of conjugate events observed simultaneously at the two stations were almost the same in September and October and decreased during November. The nonconjugate events observed only at Syowa Station were detected more often in September. The number of nonconjugate events decreased in October and November. These phenomena were mostly observed during 1,700-2,300 MLT around the geographic midnight at Syowa. On the other hand, the number of nonconjugate phenomena detected only at Husafell in iceland incrreased from September to Noverber. The occurrence peaks were around 2,100-0200 MLT, before geographci midnight at Husafell. From these statistical characteristics it is found that auroral hiss emission occurrences strongly depend on not only the magnetic local time but also the geographic local time and seasons, suggesting that auroral hiss emissions observed on the ground are strongly controlled by the sunlit effects in the topside ionosphere.

Sato, Natsuo (National Inst. of Polar Research, Tokyo (Japan)); Kokubun, Susumu (Univ. of Tokyo (Japan)); Saemundsson, T. (Univ. of Iceland, Reykjavik (Iceland))

1987-06-01

352

Eu(III) emission band changes caused by peripheral C-H/O hydrogen bonding.  

PubMed

We synthesized Eu(III) and Sm(III) complexes with tridentate phosphine oxide ligands, Eu(hfa)(3)(TPPM) and Sm(hfa)(3)(TPPM) (hfa: hexafluoroacetylacetonato, TPPM: tris(diphenylphosphinyl)methane), and we then examined their luminescent properties. In the complexes the Eu(III) and Sm(III) centres were fully surrounded by low-vibrational frequency ligands, which led to relatively high emission quantum yields (?(Eu) = 30%, ?(Sm) = 4.7%). The X-ray single crystal structures of the Eu(hfa)(3)(TPPM) revealed nona-coordinated Eu(III) complexes and C-H/O hydrogen bonding formations between the acidic hydrogen atom of the TPPM ligand and oxygen atoms of solvent molecules. The C-H/O hydrogen bonding slightly affected the coordination structure around the Eu(III) ion. Despite the seemingly small effect on the structural change, because the emission band profile of the (5)D(0)?(7)F(2) transition is sensitive to changes in the coordination environment of the Eu(III) complex, we observed a red shift in the emission spectral line. PMID:22522644

Kuramochi, Yusuke; Nakagawa, Tetsuya; Yokoo, Toshiaki; Yuasa, Junpei; Kawai, Tsuyoshi; Hasegawa, Yasuchika

2012-04-20

353

Power scaling for narrow linewidth C-band pulsed fiber lasers using a highly Er\\/Yb co-doped phosphate glass fiber  

Microsoft Academic Search

Power scaling of nanosecond fiber laser pulses with narrow linewidth has been demonstrated by using a new single-mode (SM) large-core polarization maintaining (PM) highly Er\\/Yb co-doped phosphate glass fiber (EYPhF). We used an optimized length of 12 cm of the EYPhF fiber in the power amplifier of the all-fiber MOPA chain. The pulse energy can reach 0.11 mJ for the

Wei Shi; Matthew Leigh; Jie Zong; Zhidong Yao; Shibin Jiang

2008-01-01

354

EXCITATION OF THE AROMATIC INFRARED EMISSION BANDS: CHEMICAL ENERGY IN HYDROGENATED AMORPHOUS CARBON PARTICLES?  

SciTech Connect

We outline a model for the heating of hydrogenated amorphous carbon (HAC) dust via the release of stored chemical energy and show that this energy ({approx}12 kJ mole{sup -1}) is sufficient to heat dust grains of classical size (50-1000 A) to temperatures at which they can emit at 3.3 {mu}m and other 'UIR' wavelengths. Using laboratory data, we show that this heating process is consistent with a concentration of a few percent of dangling bonds in HAC and may be initiated by the recombination of trapped H atoms. We suggest that the release of chemical energy from dust represents an additional source of excitation for the UIR bands relaxing the previous requirement that only stochastically heated molecules having fewer than {approx}50 atoms can produce emission at 3.3 {mu}m.

Duley, W. W. [Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Williams, D. A., E-mail: wwduley@uwaterloo.ca [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2011-08-20

355

Intrinsic broad-band white-light emission by a tuned, corrugated metal-organic framework.  

PubMed

Herein we report on the broad-band direct white-light originating from a single component emitter, namely a novel three-periodic metal-organic framework (MOF). This material features an unprecedented topology with (3,4)-connected nodes. The structure-function relationship in this system is driven by two complementary unique structural features: corrugation and interpenetration. Good correlation between simulated and experimental emission spectra has been attained, resulting in optimized color properties that approach requirements for solid-state lighting (SSL). Guided by the optimized calculated spectra, the tunability of the assembly was proven by the successful in-framework co-doping of Eu(3+). This resulted in significantly improved color properties, opening new paths for the rational design of alternative materials for SSL applications. PMID:22339608

Sava, Dorina F; Rohwer, Lauren E S; Rodriguez, Mark A; Nenoff, Tina M

2012-02-21

356

Probing the Effects of Interface Band Structure Using Ballistic Electron Emission Microscopy  

NASA Astrophysics Data System (ADS)

Ballistic electron emission microscopy (BEEM) is a scanning tunneling microscopy (STM) technique that can measure transport of hot electrons through materials and interfaces with high spatial and energetic resolution. Using this technique an attenuation length for electrons in the film can be extracted from the relationship between film thickness and the number of hot electrons transmitted through the film. The behavior of the attenuation lengths of carriers with energies just above the Schottky barrier height is indicative of the interface band structure. BEEM requires an additional contact to ground the metal base layer of a metal semiconductor junction. Performing BEEM in situ with the sample fabrication greatly increases the through put for these types of measurements. This presentation will detail our data on electron transport through metals and across different interfaces and also highlight our work to develop a special silicon substrate that has the extra contact and oxide hard mask built in to enable in situ BEEM without modifications to the STM.

Balsano, Robert; Labella, Vincent

2013-03-01

357

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

PubMed

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

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

2012-12-27

358

Narrow emission linewidths of positioned InAs quantum dots grown on pre-patterned GaAs(100) substrates.  

PubMed

We report photoluminescence measurements on a single layer of site-controlled InAs quantum dots (QDs) grown by molecular beam epitaxy (MBE) on pre-patterned GaAs(100) substrates with a 15 nm re-growth buffer separating the dots from the re-growth interface. A process for cleaning the re-growth interface allows us to measure single dot emission linewidths of 80 µeV under non-resonant optical excitation, similar to that observed for self-assembled QDs. The dots reveal excitonic transitions confirmed by power dependence and fine structure splitting measurements. The emission wavelengths are stable, which indicates the absence of a fluctuating charge background in the sample and confirms the cleanliness of the re-growth interface. PMID:21212488

Skiba-Szymanska, Joanna; Jamil, Ayesha; Farrer, Ian; Ward, Martin B; Nicoll, Christine A; Ellis, David J P; Griffiths, Jonathan P; Anderson, David; Jones, Geb A C; Ritchie, David A; Shields, Andrew J

2011-01-07

359

Intrinsic single-band upconversion emission in colloidal Yb/Er(Tm):Na3Zr(Hf)F7 nanocrystals.  

PubMed

Novel Yb/Er(Tm):Na(3)MF(7) (M = Zr, Hf) nanocrystals with intrinsic single-band upconversion emission, in contrast to the routine lanthanide-doped fluoride nanocrystals which show typical multi-band upconversion emissions, are reported for the first time. Specifically, the red upconversion intensity of the Yb/Er:Na(3)ZrF(7) nanocrystals is about 5 times as high as that of the hexagonal Yb/Er:NaYF(4) ones with a similar crystal size. PMID:23010848

Chen, Daqin; Lei, Lei; Zhang, Rui; Yang, Anping; Xu, Ju; Wang, Yuansheng

2012-11-01

360

Electronic Band Structure Information of GdN Extracted from x-ray Absorption and Emission Spectroscopy  

SciTech Connect

The electronic structure of GdN films grown by pulsed laser deposition has been investigated by soft x-ray absorption (XAS) and x-ray emission spectroscopy (XES) at the N K-edge. Density functional calculations within the local spin density approximation with Hubbard-U corrections of the N p weighted bands and density of states are used to extract band information from the spectra. Gd M{sub 4,5} XAS and XES spectra are also presented. The XES-XAS separation is shown to give information on the f-band spin splitting and the XAS line shapes are shown to reflect atomic multiplet effects.

Preston, A.; Ruck, B; Lambrecht, W; Piper, L; Downes, J; Smith, K; Trodahl, J

2010-01-01

361

Monitoring MODIS thermal emissive band stability through brightness temperature trending of a ground target  

NASA Astrophysics Data System (ADS)

The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the Terra and Aqua satellites have been operating since 2000 and 2002, respectively. To date both instruments have demonstrated good calibration stability for the Thermal Emissive Bands (TEB). Maintaining calibration accuracy is an important issue, as the instrument age, for continued production of high quality science data. In this paper a strategy to track the stability of MODIS TEB measurements from launch to present using a cold ground target is discussed. The land surface in the area surrounding Dome Concordia, Antarctica (75.1 S, 123.4 E) is well characterized and stable in terms of surface temperature and emissivity. A research station at Dome Concordia provides a record of climate variables and the opportunities for satellite validation field campaigns. Both MODIS instruments overpass the site 7-10 times per day, including a near-nadir overpass once every 2-3 days. The long-term data record of near-nadir Dome Concordia MODIS TEB measurements is analyzed relative to the measurements of ground-based (Automated Weather Station) and other satellite (e.g. Atmospheric Infrared Sounder (AIRS)) sensors. This approach allows for the detection of any long-term calibration drift and the calibration consistency between Aqua and Terra MODIS. Additionally, a method to correct the observed cold scene bias for Aqua MODIS versus AIRS is discussed.

Wenny, Brian N.; Xiong, Xiaoxiong

2007-10-01

362

Spontaneous emission near the band edge of a three-dimensional photonic crystal: a fractional calculus approach  

Microsoft Academic Search

We suggest a better mathematical method, fractional calculus, for studying the behavior of the atom-field interaction in photonic crystals. By studying the spontaneous emission of an atom in a photonic crystal with a one-band isotropic model, we found that the long-time inducing memory of the spontaneous emission is a fractional phenomenon. This behavior could be well described by fractional calculus.

Szu-Cheng Cheng; Jing-Nuo Wu; Ming-Rung Tsai; Wen-Feng Hsieh

2009-01-01

363

FERMI/LARGE AREA TELESCOPE DISCOVERY OF GAMMA-RAY EMISSION FROM A RELATIVISTIC JET IN THE NARROW-LINE QUASAR PMN J0948+0022  

SciTech Connect

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 H{beta} (FWHM(H{beta}) {approx}1500 km s{sup -1}), weak forbidden lines, and is therefore classified as a narrow-line type I quasar. This class of objects is thought to have relatively small black hole mass and to accrete at a high Eddington ratio. The radio loudness and variability of the compact radio core indicate the presence of a relativistic jet. Quasi-simultaneous radio/optical/X-ray and {gamma}-ray observations are presented. Both radio and {gamma}-ray emissions (observed over five months) are strongly variable. The simultaneous optical and X-ray data from Swift show a blue continuum attributed to the accretion disk and a hard X-ray spectrum attributed to the jet. The resulting broadband spectral energy distribution (SED) and, in particular, the {gamma}-ray spectrum measured by Fermi are similar to those of more powerful Flat-Spectrum Radio Quasars (FSRQs). A comparison of the radio and {gamma}-ray characteristics of PMN J0948+0022 with the other blazars detected by LAT shows that this source has a relatively low radio and {gamma}-ray power with respect to other FSRQs. The physical parameters obtained from modeling the SED also fall at the low power end of the FSRQ parameter region discussed in Celotti and Ghisellini. We suggest that the similarity of the SED of PMN J0948+0022 to that of more massive and more powerful quasars can be understood in a scenario in which the SED properties depend on the Eddington ratio rather than on the absolute power.

Abdo, A. A. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Ackermann, M.; Ajello, M.; Bechtol, K.; Bloom, E. D.; Borgland, A. W. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Axelsson, M.; Battelino, M. [Oskar Klein Centre for Cosmo Particle Physics, AlbaNova, SE-106 91 Stockholm (Sweden); Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Baughman, B. M. [Department of Physics, Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States); Bonamente, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Brigida, M.; Caliandro, G. A. [Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy); Bruel, P. [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France)], E-mail: luigi.foschini@brera.inaf.it (and others)

2009-07-10

364

The sensitivity of land emissivity estimates from AMSR-E at C and X bands to surface properties  

NASA Astrophysics Data System (ADS)

Microwave observations at low frequencies exhibit more sensitivity to surface and subsurface properties with little interference from the atmosphere. The objective of this study is to develop a global land emissivity product using passive microwave observations from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and to investigate its sensitivity to land surface properties. The developed product complements existing land emissivity products from SSM/I and AMSU by adding land emissivity estimates at two lower frequencies, 6.9 and 10.65 GHz (C- and X-band, respectively). Observations at these low frequencies penetrate deeper into the soil layer. Ancillary data used in the analysis, such as surface skin temperature and cloud mask, are obtained from International Satellite Cloud Climatology Project (ISCCP). Atmospheric properties are obtained from the TIROS Operational Vertical Sounder (TOVS) observations to determine the small upwelling and downwelling atmospheric emissions as well as the atmospheric transmission. A sensitivity test confirms the small effect of the atmosphere but shows that skin temperature accuracy can significantly affect emissivity estimates. Retrieved emissivities at C- and X-bands and their polarization differences exhibit similar patterns of variation with changes in land cover type, soil moisture, and vegetation density as seen at SSM/I-like frequencies (Ka and Ku bands). The emissivity maps from AMSR-E at these higher frequencies agree reasonably well with the existing SSM/I-based product. The inherent but small discrepancy introduced by the difference between SSM/I and AMSR-E frequencies and incidence angles has been examined and found to be small. Large differences between emissivity estimates from ascending and descending overpasses were found at the lower frequencies due to the inconsistency between the thermal IR skin temperatures and passive microwave brightness temperatures which can come from below the surface. This issue must be addressed in future studies to improve the accuracy of the emissivity estimates at lower frequencies.

Norouzi, H.; Temimi, M.; Rossow, W. B.; Pearl, C.; Azarderakhsh, M.; Khanbilvardi, R.

2011-06-01

365

Observation of nitric oxide rovibrational band head emissions in the quiescent airglow during the CIRRIS-1A space shuttle experiment  

Microsoft Academic Search

Band head emissions from highly rotationally excited NO (v, J) (J approx. equals 90) have been observed in the quiescent atmosphere at tangent heights between approximately 115 and 190 km for both sunlit and nighttime conditions. The data were obtained by the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-1A) interferometer which was operated on-board the space shuttle between 28 and

D. R. Smith; M. Ahmadjian

1993-01-01

366

K-Band of X-Ray Emission of Slow Ar exp +17 Ions in a Solid Target.  

National Technical Information Service (NTIS)

The K-band of argon ion X-ray emission arising when slow Ar exp +17 ions are incident on Be solid target has been first observed. It has been found that transitions in is state are considerabely screened. (Atomindex citation 15:031662)

E. D. Donets V. A. Trifonov G. A. Tutin V. P. Ehjsmont

1983-01-01

367

Narrow spectral emission CaMoO4: Eu3+, Dy3+, Tb3+ phosphor crystals for white light emitting diodes  

NASA Astrophysics Data System (ADS)

Alkaline earth metal molybdates are promising candidates as a host material for high efficiency narrow spectral emission phosphors. These phosphors could potentially be used for the fabrication of phosphor-converted light emitting diodes (pc-LEDs). Phosphor crystals of calcium molybdate doped with rare earth dopant Ln3+(Ln=Eu, Dy, Tb) grown using flux growth method have been shown to exhibit higher excitation efficiency than the powders synthesized by solid-state reaction process. Molybdenum (VI) oxide has been found to be a suitable flux for growing large size optically transparent high quality crystals at a temperature around 1100 °C. Using the excitation wavelengths of 465 nm, 454 nm and 489 nm for CaMoO4: Eu3+, CaMoO4: Dy3+ and CaMoO4: Tb3+, respectively, intense emission lines at wavelengths of 615 nm, 575 nm and 550 nm were observed. The optimized doping concentrations of 12%, 2% and 5% for Eu3+, Dy3+ and Tb3+, respectively, provided the highest luminescence intensity.

Khanna, A.; Dutta, P. S.

2013-02-01

368

Discovery of a TiO emission band in the infrared spectrum of the S star NP Aurigae  

NASA Astrophysics Data System (ADS)

We report on the discovery of an infrared emission band in the Spitzer spectrum of the S-type AGB star NP Aurigae that is caused by TiO molecules in the circumstellar environment. We modeled the observed emission to derive the temperature of the TiO molecules (?600 K), an upper limit on the column density (?1017.25 cm-2) and a lower limit on the spatial extent of the layer that contains these molecules. (?4.6 R?). This is the first time that this TiO emission band is observed. A search for similar emission features in the sample of S-type stars yielded two additional candidates. However, owing to the additional dust emission, the identification is less stringent. By comparing the stellar characteristics of NP Aur to those of the other stars in our sample, we find that all stars with TiO emission show large-amplitude pulsations, s-process enrichment, and a low C/O ratio. These characteristics might be necessary requirements for a star to show TiO in emission, but they are not sufficient.

Smolders, K.; Verhoelst, T.; Neyskens, P.; Blommaert, J. A. D. L.; Decin, L.; Van Winckel, H.; Van Eck, S.; Sloan, G. C.; Cami, J.; Hony, S.; De Cat, P.; Menu, J.; Vos, J.

2012-07-01

369

Unoccupied-electronic-band structure of graphite studied by angle-resolved secondary-electron emission and inverse photoemission  

NASA Astrophysics Data System (ADS)

Angle-resolved inverse photoemission spectroscopy (ARIPES) and angle-resolved secondary-electron emission spectroscopy (ARSEES) have been performed for graphite to establish experimentally the unoccupied-electronic-band structure as well as to study the difference between the two techniques. Remarkable differences have been found in the experimental two-dimensional band structures obtained by the two methods. The experimental results have been compared with the two different band calculations by R. C. Tatar and S. Rabii [Phys. Rev. B 25, 4126 (1982)] and by N. A. W. Holzwarth, S. G. Louie, and S. Rabii [Phys. Rev. B 26, 5382 (1982)] with special attention to the energy position of the three-dimensional interlayer band. The possible origin of the difference between ARIPES and ARSEES has also been discussed.

Maeda, F.; Takahashi, T.; Ohsawa, H.; Suzuki, S.; Suematsu, H.

1988-03-01

370

Thin-walled boron nitride microtubes exhibiting intense band-edge UV emission at room temperature  

NASA Astrophysics Data System (ADS)

Boron nitride (BN) microtubes were synthesized in a vertical induction furnace using Li2CO3 and B reactants. Their structures and morphologies were investigated using x-ray diffraction, scanning and transmission electron microscopy, and energy-dispersive x-ray spectroscopy. The microtubes have diameters of 1-3 µm, lengths of up to hundreds of micrometers, and well-structured ultrathin walls only ~50 nm thick. A mechanism combining the vapor-liquid-solid (VLS) and template self-sacrificing processes is proposed to explain the formation of these novel one-dimensional microstructures, in which the Li2O-B2O3 eutectic reaction plays an important role. Cathodoluminescence studies show that even at room temperature the thin-walled BN microtubes can possess an intense band-edge emission at ~216.5 nm, which is distinct compared with other BN nanostructures. The study suggests that the thin-walled BN microtubes should be promising for constructing compact deep UV devices and find potential applications in microreactors and microfluidic and drug delivery systems.

Huang, Yang; Bando, Yoshio; Tang, Chengchun; Zhi, Chunyi; Terao, Takeshi; Dierre, Benjamin; Sekiguchi, Takashi; Golberg, Dmitri

2009-02-01

371

Vertical and horizontal phase propagation in the mesopause region observed by the OI5577 angstrom, O/sub 2 atmospheric band, NaD and OH(8,3) band nightglow emissions  

NASA Astrophysics Data System (ADS)

The upper mesospheric and lower thermospheric nightglow OI5577A, O Atmospheric band at 8645A, NaD and OH(8,3) band emissions by multichannel tilting filter type zenith photometers, and the NaD and OH(8,3) band emissions by a meridional scanning photometer were measured simultaneously. The nocturnal intensity variations and the meridional scanning observations show vertical and horizontal phase propagation, respectively, in the emission layers. The observations are presented and the effects of the upper atmosphere tidal wave and gravity wave propagations are discussed.

Takahashi, H.; Batista, P. P.; Sahai, Y.; Clemesha, B. R.

1984-02-01

372

InAs\\/InP\\/ZnSe core\\/shell\\/shell quantum dots as near-infrared emitters: Bright, narrow-band, non-cadmium containing, and biocompatible  

Microsoft Academic Search

High quality InAs\\/InP\\/ZnSe core\\/shell\\/shell quantum dots have been grown by a one-pot approach. This engineered quantum dots\\u000a with unique near-infrared (NIR) fluorescence, possessing outstanding optical properties, and the biocompatibility desired\\u000a for in vivo applications. The resulting quantum dots have significantly lower intrinsic toxicity compared to NIR emissive\\u000a dots containing elements such as cadmium, mercury, or lead. Also, these newly developed

Renguo Xie; Kai Chen; Xiaoyuan Chen; Xiaogang Peng

2008-01-01

373

InAs/InP/ZnSe Core/Shell/Shell Quantum Dots as Near-Infrared Emitters: Bright, Narrow-Band, Non-Cadmium Containing, and Biocompatible.  

PubMed

High quality InAs/InP/ZnSe core/shell/shell quantum dots have been grown by a one-pot approach. This engineered quantum dots with unique near-infrared (NIR) fluorescence, possessing outstanding optical properties, and the biocompatibility desired for in vivo applications. The resulting quantum dots have significantly lower intrinsic toxicity compared to NIR emissive dots containing elements such as cadmium, mercury, or lead. Also, these newly developed ultrasmall non-Cd containing and NIR-emitting quantum dots showed significantly improved circulation half-life and minimal reticuloendothelial system (RES) uptake. PMID:20631914

Xie, Renguo; Chen, Kai; Chen, Xiaoyuan; Peng, Xiaogang

2008-12-14

374

Hydrogenation of polycyclic aromatic hydrocarbons as a factor affecting the cosmic 6.2 micron emission band.  

PubMed

While many of the characteristics of the cosmic unidentified infrared (UIR) emission bands observed for interstellar and circumstellar sources within the Milky Way and other galaxies, can be best attributed to vibrational modes of the variants of the molecular family known as polycyclic aromatic hydrocarbons (PAH), there are open questions that need to be resolved. Among them is the observed strength of the 6.2 micron (1600 cm(-1)) band relative to other strong bands, and the generally low strength for measurements in the laboratory of the 1600 cm(-1) skeletal vibration band of many specific neutral PAH molecules. Also, experiments involving laser excitation of some gas phase neutral PAH species while producing long lifetime state emission in the 3.3 micron (3000 cm(-1)) spectral region, do not result in significant 6.2 micron (1600 cm(-1)) emission. A potentially important variant of the neutral PAH species, namely hydrogenated-PAH (H(N)-PAH) which exhibit intriguing spectral correlation with interstellar and circumstellar infrared emission and the 2175 A extinction feature, may be a factor affecting the strength of 6.2 micron emission. These species are hybrids of aromatic and cycloalkane structures. Laboratory infrared absorption spectroscopy augmented by density function theory (DFT) computations of selected partially hydrogenated-PAH molecules, demonstrates enhanced 6.2 micron (1600 cm(-1)) region skeletal vibration mode strength for these molecules relative to the normal PAH form. This along with other factors such as ionization or the incorporation of nitrogen or oxygen atoms could be a reason for the strength of the cosmic 6.2 micron (1600 cm(-1)) feature. PMID:11345250

Beegle, L W; Wdowiak, T J; Harrison, J G

2001-03-15

375

DETECTION OF K{sub S} -BAND THERMAL EMISSION FROM WASP-3b  

SciTech Connect

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.

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

376

Coherent Control of Spontaneous Emission near a Photonic Band Edge: A Single-Atom Optical Memory Device  

NASA Astrophysics Data System (ADS)

We demonstrate coherent control of spontaneous emission from a three-level atom with one resonant frequency near the edge of a photonic band gap. As a result of quantum interference and photon localization, spontaneous emission can be totally suppressed or strongly enhanced depending on the relative phase between the control and pump laser fields. The fractionalized steady state inversion of the atom depends sensitively on the initial conditions, suggesting the possibility of a phase-sensitive, optical memory device on the atomic scale.

Quang, Tran; Woldeyohannes, Mesfin; John, Sajeev; Agarwal, Girish S.

1997-12-01

377

Spontaneous emission near the band edge of a three-dimensional photonic crystal: a fractional calculus approach  

NASA Astrophysics Data System (ADS)

We suggest a better mathematical method, fractional calculus, for studying the behavior of the atom-field interaction in photonic crystals. By studying the spontaneous emission of an atom in a photonic crystal with a one-band isotropic model, we found that the long-time inducing memory of the spontaneous emission is a fractional phenomenon. This behavior could be well described by fractional calculus. The results show no steady photon-atom bound state for the atomic resonant transition frequency lying in the proximity of the allowed band edge which was encountered in a previous study (Woldeyohannes and John 2003 J. Opt. B: Quantum Semiclass. Opt. 5 R43). The correctness of this result is validated by the 'cut-off smoothing' density of photon states (DOS) with fractional calculus. By obtaining a rigorous solution without the multiple-valued problem for the system, we show that the method of fractional calculus has a logically concise property.

Cheng, Szu-Cheng; Wu, Jing-Nuo; Tsai, Ming-Rung; Hsieh, Wen-Feng

2009-01-01

378

Experimental Evaluation of Predissociation Rate in v=4 State Usable for Analysis of H2 Fulcher-? Band Emission  

NASA Astrophysics Data System (ADS)

A decrease in emission intensity owing to predissociation in the Fulcher-? band (d3\\Pi u ? a3? g+) in the d3\\Pi u (v'=4) vibronic state of H2 was investigated. The measured population in the d3\\Pi u (v'=4) state, which is above the dissociation limit to H(1s) and H(2s), was compared with that predicted from d3\\Pi u (v'=0--3) emission, which does not suffer predissociation. We measured the pressure dependence of the Fulcher-? band spectra in a hollow-cathode glow discharge apparatus. From the linear dependence of collisional quenching rate on gas pressure, predissociation rate was determined, and it was verified by applying it to low-pressure arc discharge plasmas of < 2 Pa in the divertor simulator MAP-II, in which collisional quenching can be neglected.

Yamasaki, Daisuke; Kado, Shinichiro; Xiao, Bingjia; Iida, Yohei; Kajita, Shin; Tanaka, Satoru

2006-04-01

379

Evolution of the GaNxP1-x alloy band structure: A ballistic electron emission spectroscopic investigation  

Microsoft Academic Search

The evolution of the band structure of the GaNxP1-x alloy, under dilute nitrogen concentrations (x=0, 0.0028, 0.0086, 0.0210, and 0.0310), is investigated using ballistic electron emission spectroscopy (BEES). The observation of fine structure in the BEES spectra of GaNP samples is discussed in terms of a possible splitting in the degeneracy of the X valley due to the nitrogen induced

C. V. Reddy; R. E. Martinez; V. Narayanamurti; H. P. Xin; C. W. Tu

2002-01-01

380

Evolution of the GaNxP1-x alloy band structure:?A ballistic electron emission spectroscopic investigation  

Microsoft Academic Search

The evolution of the band structure of the GaNxP12x alloy, under dilute nitrogen concentrations ( x50, 0.0028, 0.0086, 0.0210, and 0.0310!, is investigated using ballistic electron emission spectroscopy ~BEES!. The observation of fine structure in the BEES spectra of GaNP samples is discussed in terms of a possible splitting in the degeneracy of the X valley due to the nitrogen

C. V. Reddy; R. E. Martinez II; V. Narayanamurti; H. P. Xin; C. W. Tu

2002-01-01

381

Midwinter intensities of the night airglow O2 (0-1) atmospheric band emission at high latitudes  

Microsoft Academic Search

Absolute intensities of the O2 (0-1) atmospheric band night airglow emission have been observed from near Longyearbyen on West Spitsbergen (78.4 deg N latitude, 15 deg E longitude, geographic) during a 2-month period around winter solstice (1982-1983). Intensities ranging from 110 R to 1590 R with a mean of 570 R + or - 60 R are observed. There is

H. K. Myrabo; C. S. Deehr; G. J. Romick; K. Henriksen

1986-01-01

382

Blue and red emission in wide band gap BaZrO 3:Yb 3+,Tm 3+  

Microsoft Academic Search

Under NIR excitation at 967 intense blue and red photoluminescence (PL) emissions are observed at room temperature in codoped Tm3+–Yb3+ barium zirconate (BaZrO3:Yb,Tm) powders. Powders were prepared by a simple hydrothermal method, and present a wide band gap that depends on the total rare earth content due to the degree of disorder induced in the BaZrO3 lattice by the substitution

R. Borja-Urby; L. A. Diaz-Torres; P. Salas; M. Vega-Gonzalez; C. Angeles-Chavez

2010-01-01

383

Analysis of thermal band gap variations of PbS quantum dots by Fourier transform transmission and emission spectroscopy  

NASA Astrophysics Data System (ADS)

Fourier transmission and emission spectroscopy was employed in the range from 5 to 300 K to measure the thermal band gap shift of 4.7 nm PbS quantum dots. The analytical comparison of fits carried out with the expressions of Varshni and Fan revealed limited accuracy of the Varshni fitting parameters. Evidence is presented that transmission spectroscopy in conjunction with the Fan model concurs with the microscopic material features, resulting in a tool to determine intrinsic properties of quantum dots.

Ullrich, B.; Wang, J. S.; Brown, G. J.

2011-08-01

384

Interstellar polycyclic aromatic hydrocarbons - The infrared emission bands, the excitation\\/emission mechanism, and the astrophysical implications  

Microsoft Academic Search

A comprehensive study of the PAH hypothesis is presented, including the interstellar, IR spectral features which have been attributed to emission from highly vibrationally excited PAHs. Spectroscopic and IR emission features are discussed in detail. A method for calculating the IR fluorescence spectrum from a vibrationally excited molecule is described. Analysis of interstellar spectrum suggests that the PAHs which dominate

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

1989-01-01

385

L to X-Band Scatter and Emission Measurements of Vegetation.  

National Technical Information Service (NTIS)

A broad-band H and V polarization radiometer was combined with a noise transmitter to an instrument for measuring active and passive microwave signatures at seven frequencies between L and X band. This radiometer-scatterometer is operated from a cherry pi...

R. Hueppi E. Schanda

1986-01-01

386

Application of band-target entropy minimization to infrared emission spectroscopy and the reconstruction of pure component emissivities from thin films and liquid samples.  

PubMed

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

Cheng, Shuying; Rajarathnam, D; Meiling, Tan; Garland, Marc

2006-05-01

387

Doubly enhanced spontaneous emission due to increased photon density of states at photonic band edge frequencies.  

PubMed

Double enhancement of spontaneous emission due to increased photon density of states at the emission frequency and the small group velocity of light at the excitation frequency was clearly demonstrated by angle-resolved photoluminescence experiments for dielectric multilayers composed of Ta2O5 and SiO2 with oxygen vacancies as light emitters. Theoretical emission profiles given by the weak modulation approximation agreed well with the experimental observations. PMID:19654722

Kuroda, Keiji; Sawada, Tsutomu; Kuroda, Takashi; Watanabe, Kenji; Sakoda, Kazuaki

2009-07-20

388

Remote monitoring of a multi-component liquid-phase organic synthesis by infrared emission spectroscopy: the recovery of pure component emissivities by band-target entropy minimization.  

PubMed

A liquid-phase cycloaddition reaction near ambient temperature involving dimethyl acetylenedicarboxylate (DMAD) and cyclopentadiene (CP) as reactants was measured using a conventional Fourier transform infrared (FT-IR) spectrometer with an emission accessory. Two semi-batch experiments were performed and a total of 55 spectra were collected using a DTGS detector. Band-target entropy minimization (BTEM), a pure component spectral reconstruction technique, was applied to analyze the data set to retrieve the pure component emission spectrum from the reaction system. The estimated emission spectra of the solvent chloroform, DMAD, CP, and product, namely dimethyl bicyclo[2.2.1]-2,5-heptadiene-2,3-dicarboxylate, were all reconstructed with rather good quality. The estimated emission spectra are similar to independent FT-IR spectra of the same cycloaddition reaction. Using a least squares fit, the relative concentration profiles of the species are obtained. Because this appears to be the first time that a liquid-phase reaction has been monitored by infrared emission spectroscopy, further improvements and opportunities for general multi-phase liquid reaction monitoring are discussed. PMID:17958955

Cheng, Shuying; Tjahjono, Martin; Rajarathnam, D; Chuanzhao, Li; Lyapkalo, Ilya; Chen, David; Garland, Marc

2007-10-01

389

The 217.5 nm Band, Infrared Absorption, and Infrared Emission Features in Hydrogenated Amorphous Carbon Nanoparticles  

NASA Astrophysics Data System (ADS)

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 2/sp 3 ratio ? 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.

Duley, W. W.; Hu, Anming

2012-12-01

390

THE 217.5 nm BAND, INFRARED ABSORPTION, AND INFRARED EMISSION FEATURES IN HYDROGENATED AMORPHOUS CARBON NANOPARTICLES  

SciTech Connect

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.

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

391

Magnetospheric Banded Emissions: Their Distribution, Amplitude and Frequency Shifts, and Ambient Plasma and Cyclotron Frequencies as Determined by IMAGE/RPI  

NASA Astrophysics Data System (ADS)

Magnetospheric banded emissions were investigated using both a statistical analysis and by performing detailed case studies with an emphasis on the dynamics near the magnetic equator. An algorithm to automatically search radio-wave dynamic spectra was used to determine the number of bands detected, their spatial distribution and the ambient plasma conditions in the emission generation regions. The algorithm was applied to Jan 2001 - August 2004 data from the Radio Plasma Imager (RPI) on the IMAGE satellite. The statistical results indicated that when the electron plasma frequency could be determined the banded emissions were most common when (1) the electron plasma to cyclotron frequency ratio was between 7 and 8, (2) the L value was between 5 and 8, (3) the magnetic local time was between 15 and 16 hours, (4) the radial distance was between 5.5 and 7 Earth radii, and (4) IMAGE was located near the magnetic equator but there was a tendency for banded emissions to be observed more often at positive than at negative magnetic latitudes. The case studies indicated that (1) the sudden onset of banded emissions corresponds to a rapid drop in the electron plasma to cyclotron frequency ratio, (2) large positive frequency deviations in the banded emissions from values near the midpoints between the electron cyclotron harmonics occur near the magnetic equator, (3) these frequency increases correlate with large amplitude increases suggesting nonlinear processes.

Benson, R. F.; Webb, P. A.; Osherovich, V. A.; Medeiros, M. P.; Sandberg, J.

2006-12-01

392

Production of N2 Vegard-Kaplan and other triplet band emissions in the dayglow of Titan  

NASA Astrophysics Data System (ADS)

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.

Bhardwaj, Anil; Jain, Sonal Kumar

2012-04-01

393

Evolution of the GaNxP1-x alloy band structure:?A ballistic electron emission spectroscopic investigation  

NASA Astrophysics Data System (ADS)

The evolution of the band structure of the GaNxP1-x alloy, under dilute nitrogen concentrations (x=0, 0.0028, 0.0086, 0.0210, and 0.0310), is investigated using ballistic electron emission spectroscopy (BEES). The observation of fine structure in the BEES spectra of GaNP samples is discussed in terms of a possible splitting in the degeneracy of the X valley due to the nitrogen induced intense perturbation in the GaP lattice. For an incorporation of 3% of N, the reduction in the band gap is approximately measured to be 300 meV. The data are qualitatively described by the recent perturbed host states model of Kent and Zunger.

Reddy, C. V.; Martinez, R. E.; Narayanamurti, V.; Xin, H. P.; Tu, C. W.

2002-12-01

394

Inductorless Narrow-Band Filter/Amplifier.  

National Technical Information Service (NTIS)

An inductorless tuned circuit is described which employs a pair of directly coupled transistor stages which may be operated with a signal injected into the emitter of either transistor or may be operated as an oscillator. The transistors are selected so t...

L. L. Kleinberg

1979-01-01

395

Volume holographic narrow-band optical filter  

Microsoft Academic Search

An 0.0125-nm (FWHM) bandwidth optical filter with greater than 10 percent throughput, clean sidebands, f\\/12 speed, and a response roll-off of -40 dB\\/decade has been developed by using volume holography in photorefractive materials. The performance of the Accuwave holographic filter is characterized and compared with that of a Lyot filter, which is the standard for solar astronomy today. Moreover, this

George A. Rakuljic; Victor Leyva

1993-01-01

396

Volume holographic narrow-band optical filter.  

PubMed

An 0.0125-nm (FWHM) bandwidth optical filter with >10% throughput, clean sidebands, f/12 speed, and a response roll-off of -40 dB/decade has been developed by using volume holography in photorefractive materials. The performance of the Accuwave holographic filter is characterized and compared with that of a Lyot filter, which is the standard for solar astronomy today. Moreover, this device represents the first commercial application of volume holography in photorefractive crystals. PMID:19802168

Rakuljic, G A; Leyva, V

1993-03-15

397

Synchrotron studies of narrow band materials  

SciTech Connect

Since last year, we have had three 3-week blocks of beamtime, in April and November 1991 and February 1992, on the Ames/Montana beamline at the Wisconsin Synchrotron Radiation Center (SRC). These runs continued our program on high temperature superconductors, heavy Fermion and related uranium and rare earth materials, and started some work on transition metal oxides. We have also had beamtime at the Brookhaven NSLS, 5 days of beamtime on the Dragon monochromator, beamline U4B, studying resonant photoemission of transition metal oxides using photon energies around the transition metal 2p edges. Data from past runs has been analyzed, and in some cases combined with photoemission and bremsstrahlung isochromat spectroscopy (BIS) data taken in the home U-M lab. 1 fig.

Not Available

1992-01-01

398

Measurement of the AlGaInAs\\/AlGaAs conduction-band offset using ballistic electron emission spectroscopy  

Microsoft Academic Search

Ballistic electron emission spectroscopy (BEES) has been used to determine the conduction-band offset between a 10-nm-thick Al0.12In0.22Ga0.66As (Q) strained layer and a ternary Al0.2Ga0.8As (T) barrier located beneath the surface. A three-sample process was used so that the known, reproducible Au\\/GaAs Schottky barrier would be the top layer of all measured structures. BEES thresholds obtained for Au\\/GaAs, Au\\/GaAs\\/Q, and Au\\/GaAs\\/Q\\/T

S. Bhargava; C. Zheng; J. Ko; M. A. Chin; L. A. Coldren; V. Narayanamurti

1998-01-01

399

Detection of CO Cameron band emission in comet P/Hartley 2 (1991 XV) with the Hubble Space Telescope  

NASA Astrophysics Data System (ADS)

Ultraviolet (UV) spectra of comet P/Hartley 2 (1991 XV) taken with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) in 1991 September reveal several bands of the Cameron system of CO (a 3 Pi-X 1 Sigma). These band are most likely due to 'prompt' emission from CO2 and, thus, provide a direct tracer of the CO2 abundance in the nucleus. Photodissociative excitation of CO2 is probably the largest contributor to the Cameron band emission, but significant contributions from electron impact excitation of CO, electron impact dissociation of CO2, and dissociative recombination of CO2(+), are also possible. Using our estimate that photodissociative excitation is responsible for approximately 60% of the total excitation of the Cameron system, we derive QCO2 approximately 2.6 x 1027 molecules/s, which implies CO2/H20 approximately 4%. If all of the Cameron band emission is due to photodissociative excitation, then CO2/H2O = 7 +/- 2%. For the largest possible contributions from the other excitation mechanisms considered, the CO2 abundance could be as a small as aproximately 2-3%. We did not detect CO Fourth Positive Group emission in our data and derive an upper limit of CO/H2O less than or equal to 1% (3 sigma) for CO coming directly from the nucleus. Comparison of the relative CO2 and CO abundances in P/Hartley 2 to those in P/Halley (CO2/H2O approximately 3%-4%, CO/H20 approximately 4% for the nucleus source) indicates that selective devolatilization of the nucleus may have occurred for P/Hartley 2. A relatively large CO2/CO ratio (i.e., approximately greater than 1) seems to be a common property of cometary nuclei. Since gas phase chemistry, in either the solar nebula or the interstellar medium (ISM), appears incapable of producing large relative CO2 abundances, the CO2 in cometary nuclei is probably produced either by UV and/or cosmic ray irradiation of ISM grains prior to the formation of the Solar System, or by condensation fractionation in the solar nebula.

Weaver, H. A.; Feldman, P. D.; McPhate, J. B.; A'Hearn, M. F.; Arpigny, C.; Smith, T. E.

1994-02-01

400

Are the Isomers of C2H4O Responsible for the Unidentified Infrared Emission Bands and Continuum?  

NASA Astrophysics Data System (ADS)

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.

Bernstein, Lawrence; Lynch, D. K.

2009-05-01

401

Dependence of Excitonic Emission Lines and the 1.47 eV Band on Growth Temperature and Substrate Misorientation in MOCVD-Grown CdTe Films on (100) GaAs  

NASA Astrophysics Data System (ADS)

Epitaxial CdTe layers were grown on nominally (100)-oriented and 3°-off misoriented GaAs substrates at temperatures between 200 and 425°C by low-pressure metalorganic chemical vapour deposition (MOCVD) with the use of precracking (CH3)2Te gas. The excitonic features, at 4.2 K, exhibited a marked dependence not only on the orientation of the GaAs substrate, but also on growth temperature. A neutral-acceptor bound-exciton line with the narrow full width at half maximum of about 0.6 meV, in a layer on a misoriented substrate, is enhanced in intensity with increasing growth temperature. Remarkable spectral changes of the individual broad bands located in the vicinities of 1.47 and 1.42 eV were also found in the layers grown at temperatures between 350 and 400°C, where the 1.47 eV band with a weak LO-phonon coupling strength became predominant. We discuss the origin of the bound-exciton emission lines and the 1.47 eV band in the heteroepitaxial CdTe layers.

Taguchi, Tsunemasa; Suita, Muneyoshi

1989-11-01

402

Extreme ultraviolet and out-of-band radiation emission from a tin-droplet-based LPP source  

NASA Astrophysics Data System (ADS)

Extreme Ultraviolet Lithography (EUVL) is a leading candidate for the future development of smaller and faster microchips with feature sizes of 32 nm or less. Tin laser-produced plasmas (LPPs) are one of the most promising sources of in-band radiation for EUV lithography and inspection applications. However, ions emitted from these LPPs may cause significant damage to components, specifically the collector optics. Tin-droplet targets have the ability to supply the minimum mass required to generate the EUV radiation, leading to substantial decrease in the amount of generated debris. Absolute intensity measurements of the EUV radiation formed using a droplet target, have been recorded. Measurements were recorded over 2 pi steradian with respect to the plasma. The droplet generator, a fully in-house developed system, was synchronized with a Nd:YAG laser operating at a frequency of 5 kHz. The laser pulse was focused to a power density of approximately 1011 W/cm2 to maximize in-band emission. EUV measurements were recorded at the Intermediate Focus of the High Brightness Source of the Laboratory for Energy Conversion. To complement the EUV measurements, out-of-band measurements were simultaneously recorded with a calibrated spectrometer from 300 to 1000 nm.

Morris, Oran; Giovannini, Andrea Z.; Gambino, Nadia; Henderson, Ian; Abhari, Reza S.

2012-03-01

403

HITEMP derived spectral database for the prediction of jet engine exhaust infrared emission using a statistical band model  

NASA Astrophysics Data System (ADS)

The spectroscopic database HITEMP 2010 is used to upgrade the parameters of the statistical molecular band model which is part of the infrared signature prediction code NIRATAM (NATO InfraRed Air TArget Model). This band model was recommended by NASA and is applied in several codes that determine the infrared emission of combustion gases. The upgrade regards spectral absorption coefficients and line densities of the gases H2O, CO2, and CO in the spectral region 400-5000 cm-1 (2-25?m) with a spectral resolution of 5 cm-1. The temperature range 100-3000 K is covered. Two methods to update the database are presented: the usually applied method as provided in the literature and an alternative, more laborious procedure that employs least squares fitting. The achieved improvements resulting from both methods are demonstrated by comparisons of radiance spectra obtained from the band model to line-by-line results. The performance in a realistic scenario is investigated on the basis of measured and predicted spectra of a jet aircraft plume in afterburner mode.

Lindermeir, E.; Beier, K.

2012-08-01

404

Fermi gamma-ray and multi-wave band emission from TeV active galactic nuclei  

NASA Astrophysics Data System (ADS)

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.

Xiong, Dingrong; Zhang, Haojing; Zhang, Xiong; Zheng, Yonggang; Liu, Wenguang; Mao, Lisheng; Huang, Bangrong; Kang, Ting; Cha, Yongjuan; Guo, Fei

2013-01-01

405

PAH anions as carriers of the mid-IR emission bands in planetary nebulae  

NASA Astrophysics Data System (ADS)

We present results of the mid-IR spectra decomposition for planetary nebulae and compact H ii regions in our Galaxy and Magellanic Clouds. The striking correlation between the required PAH component with “7.7” ?m band shifted to about 7.8 ?m and electron densities of the modeled sources allows us to argue that this PAH component may be in fact PAH anions (PAH-).

Szczerba, Ryszard; Joblin, Christine; Berné, Olivier; Szyszka, Cezary

2008-10-01

406

Emissivity signatures in the thermal IR band for remote sensing - Calibration procedure and method of measurement  

NASA Astrophysics Data System (ADS)

Problems encountered in thermal infrared spectral emissivity signatures for remote sensing are addressed. Instrument calibration procedure is described, with particular attention to stray light effects. A method, which derives from the box method, for the absolute determination of spectral signatures of bare soils and mineral samples is proposed and illustrated with several materials (sand, loess, SiC powders). Excellent agreement is found between emissivity values obtained in this way, and values deduced from reflectivity measurements at 10.6 microns, as far as the angular behavior of the bidirectional reflectivity is taken into account. Comparison with spectral reflectivity measurements shows good spectral correlation.

Nerry, Francoise; Labed, Jeeifa; Stoll, Marc-Philippe

1988-02-01

407

Theory of Spontaneous and Stimulated Emission in Two Band Intrinsic Semiconductor  

NASA Astrophysics Data System (ADS)

The behavior of a single mode of radiation field coupled to an excited two band intrinsic semiconductor has been investigated with the help of the commutator version of evolution operator method. As dependent on the excitation level three states of the field has been shown to exist: the equilibrium with the number of photons determined by the Bose-Einstein distribution with nonzero chemical potential; the quasi-equilibrium with the average number of photons equal to unity and accompanied by fluctuations; the state of photon avalanche.

Cheltsov, Vladislav

408

Spatial-resolved cathode luminescence study of S-doped ZnO particles for the luminescence of UV, green and orange band emission  

NASA Astrophysics Data System (ADS)

The hexagonal bi-pillar structures of undoped and sulfur-doped ZnO particles have been synthesized by hydrothermal method to study the relationship between UV and long wavelength emissions, green emission (GE) and orange emission (OE) bands. A room temperature photoluminescence comparison between undoped and sulfur-doped ZnO shows an increase of long wavelength emission, that is presumably due to an increase of defects in doped ZnO. Spatial cathode luminescence (CL) analysis on a single ZnO particle shows a competitive behavior between GE and OE bands. The long wavelength emissions in ZnO are all related to Zn vacancies. GE will dominate if the Zn vacancy-related oxygen stays at lattice point; otherwise OE will dominate if this oxygen atom leaves lattice point to form a interstitial atom.

Sun, Yuanping; Guo, Hongying; Jiang, Feihong; Yuan, Run; Zhang, Jun; Zeng, Xionghui; Zhou, Taofei; Qiu, Yongxin; Zhang, Baoshun; Xu, Ke; Yang, Hui

2013-10-01

409

Theoretical predictions for the effect of nebular emission on the broad-band photometry of high-redshift galaxies  

NASA Astrophysics Data System (ADS)

By combining optical and near-IR observations from the Hubble Space Telescope with near-IR photometry from the Spitzer Space Telescope, it is possible to measure the rest-frame UV-optical colours of galaxies at z = 4-8. The UV-optical spectral energy distribution of star formation dominated galaxies is the result of several different factors. These include the joint distribution of stellar masses, ages and metallicities (solely responsible for the pure stellar spectral energy distribution), and the subsequent reprocessing by dust and gas in the interstellar medium. Using a large cosmological hydrodynamical simulation (MassiveBlack-II), we investigate the predicted spectral energy distributions of galaxies at high redshift with a particular emphasis on assessing the potential contribution of nebular emission. We find that the average (median) pure stellar UV-optical colour correlates with both luminosity and redshift such that galaxies at lower redshift and higher luminosity are typically redder. Assuming that the escape fraction of ionizing photons is close to zero, the effect of nebular emission is to redden the UV-optical 1500 - Vw colour by, on average, 0.4 mag at z = 8 declining to 0.25 mag at z = 4. Young and low-metallicity stellar populations, which typically have bluer pure stellar UV-optical colours, produce larger ionizing luminosities and are thus more strongly affected by the reddening effects of nebular emission. This causes the distribution of 1500 - Vw colours to narrow and the trends with luminosity and redshift to weaken. The strong effect of nebular emission leaves observed-frame colours critically sensitive to the redshift of the source. For example, increasing the redshift by 0.1 can result in observed-frame colours changing by up to ˜0.6. These predictions reinforce the need to include nebular emission when modelling the spectral energy distributions of galaxies at high redshift and also highlight the difficultly in interpreting the observed colours of individual galaxies without precise redshift information.

Wilkins, Stephen M.; Coulton, William; Caruana, Joseph; Croft, Rupert; Matteo, Tiziana Di; Khandai, Nishikanta; Feng, Yu; Bunker, Andrew; Elbert, Holly

2013-09-01

410

Theoretical predictions for the effect of nebular emission on the broad-band photometry of high-redshift galaxies  

NASA Astrophysics Data System (ADS)

By combining optical and near-IR observations from the Hubble Space Telescope with near-IR photometry from the Spitzer Space Telescope, it is possible to measure the rest-frame UV-optical colours of galaxies at z = 4-8. The UV-optical spectral energy distribution of star formation dominated galaxies is the result of several different factors. These include the joint distribution of stellar masses, ages and metallicities (solely responsible for the pure stellar spectral energy distribution), and the subsequent reprocessing by dust and gas in the interstellar medium. Using a large cosmological hydrodynamical simulation (MassiveBlack-II), we investigate the predicted spectral energy distributions of galaxies at high redshift with a particular emphasis on assessing the potential contribution of nebular emission. We find that the average (median) pure stellar UV-optical colour correlates with both luminosity and redshift such that galaxies at lower redshift and higher luminosity are typically redder. Assuming that the escape fraction of ionizing photons is close to zero, the effect of nebular emission is to redden the UV-optical 1500 - Vw colour by, on average, 0.4 mag at z = 8 declining to 0.25 mag at z = 4. Young and low-metallicity stellar populations, which typically have bluer pure stellar UV-optical colours, produce larger ionizing luminosities and are thus more strongly affected by the reddening effects of nebular emission. This causes the distribution of 1500 - Vw colours to narrow and the trends with luminosity and redshift to weaken. The strong effect of nebular emission leaves observed-frame colours critically sensitive to the redshift of the source. For example, increasing the redshift by 0.1 can result in observed-frame colours changing by up to ˜0.6. These predictions reinforce the need to include nebular emission when modelling the spectral energy distributions of galaxies at high redshift and also highlight the difficultly in interpreting the observed colours of individual galaxies without precise redshift information.

Wilkins, Stephen M.; Coulton, William; Caruana, Joseph; Croft, Rupert; Matteo, Tiziana Di; Khandai, Nishikanta; Feng, Yu; Bunker, Andrew; Elbert, Holly

2013-11-01

411

The electrosphere of macroscopc ""nuclei"": diffuse emissions in the MeV band from dark antimatter  

SciTech Connect

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.

Forbes, Michael Mcneil [Los Alamos National Laboratory; Lawson, Kyle [CANADA; Zhitnitsky, Ariel R [CANADA

2009-01-01

412

Broad band simulation of Gamma Ray Bursts (GRB) prompt emission in presence of an external magnetic field  

NASA Astrophysics Data System (ADS)

The origin of prompt emission in GRBs is not yet well understood. The simplest and most popular model is Synchrotron Self-Compton (SSC) emission produced by internal shocks inside an ultra-relativistic jet. However, recent observations of a delayed high energy component by the Fermi-LAT instrument have encouraged alternative models. Here we use a recently developed formulation of relativistic shocks for GRBs to simulate light curves and spectra of synchrotron and self-Compton emissions in the framework of internal shock model. This model takes into account the evolution of quantities such as densities of colliding shells, and fraction of kinetic energy transferred to electrons and to induced magnetic field. We also extend this formulation by considering the presence of a precessing external magnetic field. These simulations are very realistic and present significant improvement with respect to previous phenomenological GRB simulations. They reproduce light curves of separate peaks of real GRBs and variety of spectral slopes at E > Epeak observed by the Fermi-LAT instrument. The high energy emission can be explained by synchrotron emission and a subdominant contribution from inverse Compton. We also suggest an explanation for extended tail emission and relate it to the screening of the magnetic field and/or trapping of accelerated electrons in the electromagnetic energy structure of the plasma in the shock front. Spectral slopes of simulated bursts at E << Epeak are consistent with theoretical prediction and at E < Epeak can be flatter if the spectrum of electrons is roughly flat or has a shallow slope at low energies. The observed flat spectra at soft gamma-ray and hard x-ray bands is the evidence that there is a significant contribution at E < Epeak from lower Lorentz factor wing of electron distribution which have a roughly random acceleration rather than being thermal. This means that the state of matter in the jet at the time of ejection is most probably nonthermal. As for the effect of a precessing external magnetic field, we show that due to the fast variation of other quantities, its signature in the Power Distribution Spectrum (PDS) is significantly suppressed and only when the duration of the burst is few times longer than the oscillation period it can be detected, otherwise either it is confused with the Poisson noise or with intrinsic variations of the emission. Therefore, low significant oscillations observed in the PDS of GRB 090709a are most probably due to a precessing magnetic field.

Ziaeepour, Houri; Gardner, Brian

2011-12-01

413

Enhancement of Europium Emission Band of Europium Tetracycline Complex in the Presence of Cholesterol  

Microsoft Academic Search

We report here the observation, for the first time, of the enhancement of Europium-Tetracycline complex emission in cholesterol\\u000a solutions. This enhancement was initially observed with the addition of the enzyme cholesterol oxidase, which produces H2O2, the agent driver of the Europium tetracycline complex, to the solution. However, it was found that the enzyme is not needed\\u000a to enhance the luminescence.

Flávia Rodrigues de Oliveira Silva; Ricardo Elgul Samad; Laércio Gomes; Lilia Coronato Courrol

2008-01-01

414

A Balloon-borne Limb-Emission Sounder at 650GHz band for Stratospheric observations  

Microsoft Academic Search

We have developed a Balloon-borne Superconducting Submillimeter-Wave Limb-Emission Sounder (BSMILES) to observe stratospheric minor constituents like ozone, HCl etc. BSMILES carries a 300mm-diameter offset parabolic antenna, a 650-GHz heterodyne superconducting (SIS) low-noise receiver, and an acousto-optical spectrometer (AOS) with the bandwidth of 1GHz and the resolution of 1MHz. Gondola size is 1.35 m x 1.35 m x 1.26 m. Total

Yoshihisa Irimajiri; Satoshi Ochiai

2010-01-01

415

Effects of Phonon Coupling and Free Carriers on Band-edge Emission at Room Temperature in n-type ZnO Crystals  

SciTech Connect

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.

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

416

Band Gap Energy of Chalcopyrite Thin Film Solar Cell Absorbers Determined by Soft X-Ray Emission and Absorption Spectroscopy  

SciTech Connect

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].

Bar, M.; Weinhardt, L.; Pookpanratana, S.; Heske, C.; Nishiwaki, S.; Shafarman, W.; Fuchs, O.; Blum, M.; Yang, W.; Denlinger, J.D.

2008-05-11

417

Defect conduction bands, localization, and temperature-dependent electron emission from Al-Al2O3-Au diodes  

NASA Astrophysics Data System (ADS)

The temperature dependence of several phenomena connected with voltage-controlled negative resistance (VCNR) of Al-Al2O3-Au diodes has been measured between 200 and 300 K. These include the current-voltage (I-V) characteristics, electroluminescence (EL), and electron emission into vacuum (EM) of diodes with 12-20 nm of anodic Al2O3. There is an abrupt decrease in EM by 3 orders of magnitude as temperature decreases from 285 to 280 K. EM recovers to the same magnitude as at 300 K at ~260 K and is nearly constant between 260 and 200 K. The lower temperature at which EM recovers depends on the anodizing electrolyte. EM is decoupled from the major conduction mechanism because the voltage for maximum current of the I-V curve and the voltage threshold for EL are nearly constant over the same temperature range. A model is proposed in which defect levels of oxygen vacancies form two defect conduction bands in amorphous Al2O3. The concentration of oxygen vacancies is estimated from measurements of polarization of Al-Al2O3-Au diodes that do not break down to form VCNR in their I-V characteristics. EM at high and low temperatures is through defect conduction bands. Suppression of EM in the intermediate temperature range is due to localization of electrons caused by the irregular potential present when defect centers in the lower defect conduction band are nearly fully occupied. EM shows a temperature dependent metal-nonmetal transition while the conduction current does not.

Hickmott, T. W.

2010-11-01

418

Assessment of the NPP VIIRS RVS for the thermal emissive bands using the first pitch maneuver observations  

NASA Astrophysics Data System (ADS)

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.

Wu, A.; Xiong, X.; Chiang, K.; Sun, C.

2012-09-01

419

WIDE-BAND SUZAKU ANALYSIS OF THE PERSISTENT EMISSION FROM SGR 0501+4516 DURING THE 2008 OUTBURST  

SciTech Connect

We observed the soft gamma repeater SGR 0501+4516 with Suzaku for {approx}51 ks on 2008 August 26-27, about 4 days after its discovery. Following the first paper, which reported on the persistent soft X-ray emission and the wide-band spectrum of an intense short burst, this paper presents an analysis of the persistent broadband (1-70 keV) spectra of this source in outburst, taken with the X-ray Imaging Spectrometer (XIS) and the Hard X-ray Detector (HXD). Pulse-phase folding in the 12-35 keV HXD-PIN data on an ephemeris based on multi-satellite timing measurements at soft X-rays revealed the pulsed signals at {approx_gt}99% confidence in the hard X-ray band. The wide-band spectrum clearly consists of a soft component and a separate hard component, crossing over at {approx}7 keV. When the soft component is modeled by a blackbody plus a Comptonized blackbody, the hard component exhibits a 20-100 keV flux of 4.8{sup +0.8}{sub -0.6}(stat.){sup +0.8}{sub -0.4}(sys.) x 10{sup -11} erg s{sup -1} cm{sup -2} and a photon index of {Gamma} = 0.79{sup +0.20}{sub -0.18}(stat.){sup +0.01}{sub -0.06}(sys.). The hard X-ray data are compared with those obtained by INTEGRAL about 1 day later. Combining the present results with those on other magnetars, we discuss a possible correlation between the spectral hardness of magnetars and their characteristic age and magnetic field strengths.

Enoto, T.; Makishima, K.; Nakazawa, K.; Yamada, S. [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Rea, N. [Institut de Ciencies de l'Espai (ICE-CSIC, IEEC), Campus UAB, Facultat de Ciencies, Torre C5-parell, 2a planta, 08193 Bellaterra, Barcelona (Spain); Nakagawa, Y. E. [Cosmic Radiation Laboratory, Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198 (Japan); Sakamoto, T. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Esposito, P.; Mereghetti, S.; Tiengo, A. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica-Milano, via E. Bassini 15, 20133 Milano (Italy); Goetz, D. [CEA Saclay, DSM/Irfu/Service d'Astrophysique, Orme des Merisiers, Bat. 709, 91191 Gif sur Yvette (France); Hurley, K. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Israel, G. L.; Stella, L. [INAF-Astronomical Observatory of Rome, via Frascati 3300040 Monteporzio Catone (Italy); Kokubun, M. [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Murakami, H. [Department of Physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501 (Japan); Turolla, R. [Department of Physics, University of Padua, via Marzolo 8, 35131 Padova (Italy); Yamaoka, K.; Yoshida, A. [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 229-8558 (Japan); Zane, S. [MSSL, University College London, Holmbury St. Mary, Dorking Surrey, RH5 6NT (United Kingdom)

2010-05-20

420

Interaction of wide band gap single crystals with 248 nm excimer laser radiation. XII. The emission of negative atomic ions from alkali halides  

NASA Astrophysics Data System (ADS)

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- is formed by the sequential attachment of two electrons to K+.

Kimura, Kenichi; Langford, S. C.; Dickinson, J. T.

2007-12-01

421

Enhancement of Spontaneous Erbium Emission near the Photonic Band Edge of Distributed Bragg Reflectors Based on a-Si:H/a-SiO{sub x}:H  

SciTech Connect

Results obtained in an experimental study of spontaneous emission from erbium ions in a spectral range corresponding to the lower photonic band edge of distributed Bragg reflectors (1D photonic crystals) are presented. The photonic crystals were constituted of alternating quarter-wave a-Si:H and a-SiO{sub x}:H layers grown by PECVD. Erbium was introduced into the a-Si:H layers by magnetron sputtering of an erbium target in the course of structure growth. The change observed in the intensity of spontaneous emission is due to the nonmonotonic behavior of the density of optical modes near the photonic band edge.

Medvedev, A.V.; Feoktistov, N.A.; Pevtsov, A.B.; Golubev, V.G. [Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, 194021 (Russian Federation)

2005-11-15

422

Adjustable gastric banding (image)  

MedlinePLUS

... stomach near its upper end, creating the small pouch and a narrow passage into the larger remaining ... passage delays the emptying of food from the pouch and causes a feeling of fullness. The band ...

423

Magellanic Cloud stars with TiO bands in emission: binary post-RGB/AGB stars or young stellar objects?  

NASA Astrophysics Data System (ADS)

14 stars from a sample of Magellanic Cloud objects selected to have a mid-infrared flux excess have been found to also show TiO bands in emission. The mid-infrared dust emission and the TiO band emission indicate that these stars have large amounts of hot circumstellar dust and gas in close proximity to the central star. The luminosities of the sources are typically several thousand L?, while the effective temperatures are ˜4000-8000 K which puts them bluewards of the giant branch. Such stars could be post-asymptotic giant branch (post-AGB) stars of mass ˜0.4-0.8 M? or pre-main-sequence stars (young stellar objects) with masses in the range ˜7-19 M?. If the stars are pre-main-sequence stars, they are substantially cooler and younger than stars at the birth line where Galactic protostars are first supposed to become optically visible out of their molecular clouds. They should therefore be hidden in their present evolutionary state, although this problem may be overcome if asymmetries are invoked or if the reduced metallicity of the Small Magellanic Cloud and Large Magellanic Cloud compared to the Galaxy makes the circumstellar material more transparent. The second explanation for these stars is that they are post-AGB or post-red giant branch stars that have recently undergone a binary interaction when the red giant of the binary system filled its Roche lobe. Being oxygen-rich, they have gone through this process before becoming carbon stars. Most of the stars vary slowly on time-scales of 1000 d or more, suggesting a changing circumstellar environment. Apart from the slow variations, most stars also show variability with periods of tens to hundreds of days. One star shows a period that is rapidly decreasing and we speculate that this star may have accreted a large blob of gas and dust on to a disc whose orbital radius is shrinking rapidly. Another star has Cepheid-like pulsations of rapidly increasing amplitude, suggesting a rapid rate of evolution. Seven stars show quasi-periodic variability and one star has a light curve similar to that of an eclipsing binary.

Wood, P. R.; Kamath, D.; Van Winckel, H.

2013-10-01

424

K ? band in the x-ray emission spectrum of nitrogen in A III B V -type nitrides and some of their properties  

Microsoft Academic Search

The x-ray emission spectra of nitrogen have been studied for this group of nitrides either together with the spectra of the second component [12-15] or in isolation [2]. The x-ray K spectrum of nitrogen in gallium nitride has not been studied. In order to systematize and supplement the existing incomplete data we have studied the x-ray emission Ka band of

N. N. Vasilenko; M. D. Lyutaya; E. A. Zhurakovskii; N. Frantsevich

1974-01-01

425

Observations of molecular oxygen Atmospheric band emission in the thermosphere using the near infrared spectrometer on the ISS/RAIDS experiment  

NASA Astrophysics Data System (ADS)

Observations of airglow emission using the RAIDS (Remote Atmospheric and Ionospheric Detection System) instruments on the International Space Station Kibo module are reported and compared to a photochemical model of the emission process. Launched in Sept. 2009, RAIDS performed routine observations of the O2(b1? ? X3?) Atmospheric band (O2 A-band) transition during solar minimum conditions from October 2009 to December 2010. Limb brightness of the (0,0), (0,1) and (1,1) vibration band emissions were measured in the altitude range 80 to 180 km with the Near Infrared Spectrometer (NIRS) instrument, one of eight limb viewing instruments in the RAIDS experiment. Comparison of observed brightness profiles with the model shows very good agreement for the (0,0) and (0,1) bands. The model underestimates the (1,1) brightness profiles throughout the region, especially near the peak. Reasonable variations of composition and selected rate constants do not account for the underestimation of (1,1) band brightness. A contributing factor could be in the assumption of detailed balance and the accepted energy transfer pathways that redistribute energy between the v = 0 and v = 1 states.

Christensen, Andrew B.; Yee, Jeng-Hwa; Bishop, Rebecca L.; Budzien, Scott A.; Hecht, James H.; Sivjee, Gulamabas; Stephan, Andrew W.

2012-04-01

426

Determination of the sea surface emissivity at L-band and application to SMOS salinity retrieval algorithms: Review of the contributions of the UPC-ICM  

Microsoft Academic Search

This work describes the main effects that have to be taken into account to model the sea surface emission at L-band, and the existing approaches to perform the sea surface salinity retrieval from multiangular radiometric measurements. This manuscript reviews the activities carried out in these fields during the past years by the Universitat Politècnica de Catalunya (UPC) in collaboration with

A. Camps; M. Vall-llossera; I. Corbella; N. Duffo; F. Torres; S. Blanch; A. Aguasca; R. Villarino; C. Gabarró; L. Enrique; J. Miranda; R. Sabia; M. Talone

2008-01-01