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1

Photonic crystals for narrow-band infrared emission  

NASA Astrophysics Data System (ADS)

MEMS silicon (Si) micro-bridge elements, with photonic band gap (PBG) modified surfaces are exploited for narrow-band spectral tuning in the infrared wavelength regime. Thermally isolated, uniformly heated single crystal Si micro-heaters would otherwise provide gray-body emission, in accordance with Planck's distribution function. The introduction of an artificial dielectric periodicity in the Si, with a surface, vapor-deposited gold (Au) metal film, governs the photonic frequency spectrum of permitted propagation, which then couples with surface plasmon states at the metal surface. Narrow band spectral tuning was accomplished through control of symmetry and lattice spacing of the PBG patterns. Transfer matrix calculations were used to model the frequency dependence of reflectance for several lattice spacings. Theoretical predictions that showed narrow-band reflectance at relevant wavelengths for gas sensing and detection were then compared to measured reflectance spectra from processed devices. Narrow band infrared emission was confirmed on both conductively heated and electrically driven devices.

Pralle, Martin U.; McNeal, Mark P.; Moelders, Nicholas; Last, Lisa; Ho, William; Greenwald, Anton C.; Daly, James T.; Puscasu, Irina; Johnson, Edward A.; El-Kady, Ihab; Biswas, Rana

2002-02-01

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

Narrow-Band Evoked Oto-Acoustic Emission from Ears with Normal and Pathologic Conditions  

Microsoft Academic Search

Conclusion: Evoked oto-acoustic emission (EOAE), in particular the slow component, is fragile with the inner ear lesions and is apt to disappear in impaired ears. This presence is thought to mean that inner ear is not badly damaged, and that the presence of EOAEs in early stage sudden deafness carries a good prognosis. Narrow-band EOAE analysis would open a potentially

Taizo Takeda; Akinobu Kakigi; Shinji Takebayashi; Satoshi Ohono; Rie Nishioka; Hiroaki Nakatani

2009-01-01

4

The Stellar Population Completeness of Narrow-band Emission-line Surveys  

NASA Astrophysics Data System (ADS)

Narrow-band surveys have been conducted to identify high redshift star-forming galaxies by detecting their nebular emission lines when redshifted into narrow bandpasses. Such surveys have yielded large samples from low redshifts (z<0.4) to as high as z=7. These surveys have the ability to (1) measure redshifts to 1 percent accuracy, (2) derive robust emission line fluxes, which can be used to determine star-formation rates (SFRs) and trace the cosmic SFR density, and (3) is roughly ten times more efficient than spectroscopic surveys in terms of (1) and (2). In this poster, we illustrate a unique advantage of these narrow-band surveys in identifying star-forming galaxies that span a wide range of physical properties. This survey is the first to study the stellar population completeness of emission-line surveys. It utilizes two samples of [O II] emitters at z=1.47 and z=1.61 in the Subaru Deep Field. The survey consists of 1,200 emission-line galaxies with accurate photometric redshifts, and photometric coverage over 22 wave-bands (1500 Angstroms to 4.5 µm). We find that these [O II] samples simultaneously probed the two extremes (from the bluest to the reddest) of galaxy populations. That is, the [O II] emitters are also selected as BX/BM (UV) galaxies and/or the star-forming BzK (NIR) galaxies. We attribute this success to the adopted low minimum observed equivalent width (EW) of 10 Angstroms. In addition, we find that roughly 10% of the z=1.47 [O II] emitters are not selected by either the UV or NIR techniques. These galaxies have the reddest rest-frame optical colors and very low [O II] EWs. We argue that ultra-deep narrow-band surveys are able to catch the most reddenned galaxies by detecting their weak, dust-obscured emission lines, which standard color selections, including NIR techniques, miss.

Ly, Chun; Malkan, M. A.; Ross, N.; Ota, K.; Kashikawa, N.; Iye, M.

2011-01-01

5

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

6

Stimulated emission of LO phonons in narrow-band-gap semiconductors  

Microsoft Academic Search

We investigate the physical effects of interband transitions induced by resonant longitudinal-optic (LO) phonons in narrow-band-gap n- and p-type Pb1-xSnxTe. With the band gap Eg close to the LO-phonon energy homegaL, (i) we evaluate the dielectric function that contains contributions from interband transitions induced by the LO phonons interacting with carriers, as well as by the Coulomb potential between carriers,

R. B. Sohn; L. R. Ram-Mohan; H. Xie; Peter A. Wolff

1990-01-01

7

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

8

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

NASA Astrophysics Data System (ADS)

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

Hong, Sungryong; Calzetti, Daniela; Dickinson, Mark

2014-01-01

9

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

2012-05-01

10

Narrow-band reflecting filters  

Microsoft Academic Search

A narrowing of the band of maximum reflection as compared with the band of a classical quarter-wave multilayer system can be obtained in two ways. One of these is to reduce the difference in refractive index An = nH-n L between the alternate layers [1]. In this case, in order to preserve the large values of reflection coefficients at the

I. N. Shklyarevskii; R. I. Umerov; E. A. Lupashko; I. I. Kalimanova

1970-01-01

11

Thermionic electron emission from narrow band-gap semiconductors under picosecond laser excitation  

Microsoft Academic Search

A model is presented to relate picosecond laser induced thermionic electron emission to the carrier and phonon dynamics of semiconductors. Silicon is chosen as a model material since its optical and thermal properties are well characterized. The temporal profiles of thermionic emission current and total electron yield are obtained as a function of incident laser fluence for different surface conditions,

Samuel S. Mao; Xianglei Mao; Jong H. Yoo; Ralph Greif; Richard E. Russo

1998-01-01

12

Thermionic electron emission from narrow band-gap semiconductors under picosecond laser excitation  

SciTech Connect

A model is presented to relate picosecond laser induced thermionic electron emission to the carrier and phonon dynamics of semiconductors. Silicon is chosen as a model material since its optical and thermal properties are well characterized. The temporal profiles of thermionic emission current and total electron yield are obtained as a function of incident laser fluence for different surface conditions, below the silicon surface melting threshold. Two distinct regimes have been found for the dependence of the electron yield on the laser fluence due to thermionic emission and this behavior is related to Auger recombination.

Mao, S.S.; Mao, X.; Yoo, J.H.; Greif, R.; Russo, R.E. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

1998-04-01

13

Spatial distribution of 6300A emission determined from narrow-band images of Halley's Comet  

NASA Technical Reports Server (NTRS)

In March 1986 the Wisconsin dual-etalon Fabry-Perot spectrometer was adapted for use with an intensified CCD imaging detector and good quality images of OI 6300A emission from a 10 arcmin field centered on Halley's comet head were obtained in April and May 1986. The 10 km/sec bandpass was adequate to eliminate spectral contamination from cometary NH2 and, with appropriate Doppler shifts, terrestrial airglow. The observed distribution of OI emission indicates O(sup 1)D production from 2 sources, presumably photodissociation of H2O and OH. Scale lengths are determined for the distributions of these sources in the coma.

Roesler, F. L.; Scherb, F.; Magee-Sauer, K.; Harlander, J.; Reynolds, R. J.; Oliversen, R. J.; Yelle, R. V.; Broadfoot, A. L.

1986-01-01

14

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

Microsoft Academic Search

Electrically-driven light emission from carbon nanotubes could be exploited in nano-scale lasers and single-photon sources, and has therefore been the focus of much research. However, to date, high electric fields and currents have been either required for electroluminescence, or have been an undesired side effect, leading to high power requirements and low efficiencies. In addition, electroluminescent linewidths have been broad

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

2010-01-01

15

Far-infrared emission by resonant-polaron effects in narrow-band-gap Hg(1-x)Cd(x)Te  

Microsoft Academic Search

The first experimental observation of far-infrared emission within the reststrahlen band of a semiconductor is reported. Fourier-transform emission experiments on narrow-band-gap Hg(1-x)Cd(x)Te have been performed (x roughly 0.17). Under Ar(+)-laser excitation, an emission spectrum is found at the longitudinal-optical-phonon energies of the material (137.5 and 157.5\\/cm). The appearance of the optical emission signal is caused by interband polaron effects arising

F. Fuchs; H. Schneider; P. Koidl; K. Schwarz; H. Walcher; R. Triboulet

1991-01-01

16

Narrow Band Gap Amorphous Silicon Semiconductors.  

National Technical Information Service (NTIS)

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...

A. Madan A. H. Mahan

1985-01-01

17

Electron strings in solids with narrow bands  

Microsoft Academic Search

Electronic phase separation may arise due to electron–phonon interactions. In polar materials with a narrow band this polarization effect may lead to the creation of electron strings, whose length depends on dielectric constants.

F. V. Kusmartsev

2000-01-01

18

Transition Temperature of Narrow-Band Superconductors  

Microsoft Academic Search

The equation for the vertex part of a Cooper pair is developed in the Wannier representation to highlight the atomic nature of the electrons responsible for superconductivity in narrow energy bands. For a nondegenerate band and a short-range interaction between two electrons at sites n-->1 and n-->2, the transition temperature Tc is determined by a small set of coupled integral

J. Appel; W. Kohn

1971-01-01

19

Narrow-Band Applications of Communications Satellites.  

ERIC Educational Resources Information Center

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

Cowlan, Bert; Horowitz, Andrew

20

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

21

Mass enhancement in narrow-band systems  

Microsoft Academic Search

A perturbative study of the Holstein molecular crystal model which accounts for lattice structure and dimensionality effects is presented. Anti-adiabatic conditions peculiar to narrow-band materials and an intermediate-to-strong electron-phonon coupling are assumed. The polaron effective mass depends crucially in all dimensions on the intermolecular coupling strengths which also affect the size of the lattice deformation associated with the small-polaron formation.

Marco Zoli

2000-01-01

22

Tunable narrow-band infrared emitters from hexagonal lattices  

NASA Astrophysics Data System (ADS)

In this work, we present both the theoretical basis as well as supporting experimental measurements for development of a novel mid-infrared thermally stimulated narrow band emitter with a spectral bandwidth of less than 10%. To achieve this, we utilize a metallized-surface 2D photonic crystal of air voids in a silicon background with hexagonal structure symmetry. Our results are based on the generation of discrete surface plasmon (SP) modes in the thin metallized layer residing on the top surface. This yields a series of adequately spaced discrete peaks in the reflection spectrum, dominated by a single sharp feature corresponding to the lowest plasmon order, in an otherwise uniform highly reflective spectrum (>90%) over most of the IR spectrum. This, in turn, gives rise to a sharp absorption feature with a correspondingly narrow thermal emission peak in the emission spectrum. Transfer matrix calculations simulate well both the position and strengths of the absorption peaks. By altering the period of the surface photonic lattice, the SP peak and emissive band can be tuned to the desired wavelength. These devices promise a new class of tunable infrared emitters with high power in a narrow spectral bandwidth. Such narrow band sources are critical to achieving high efficiency gas sensors.

El-Kady, I.; Biswas, R.; Ye, Y.; Su, M. F.; Puscasu, I.; Pralle, Martin; Johnson, E. A.; Daly, J.; Greenwald, A.

2003-12-01

23

Electron-hole recombination in narrow-band-gap Hg1-xCdxTe and stimulated emission of LO phonons  

Microsoft Academic Search

We investigate the dielectric properties of narrow-band-gap Hg1-xCdxTe under the resonant condition of the band gap Eg matching the longitudinal-optic (LO) phonon energy homegaL. The effect of interband transitions, which are now also induced by LO phonons, is to renormalize the mixed LO-phonon-plasmon mode downward in energy by ~20%. We evaluate the gain in the mixed mode under conditions of

H. Xie; L. R. Ram-Mohan; Peter A. Wolff

1990-01-01

24

Narrow band photometry of selected asteroids  

NASA Technical Reports Server (NTRS)

The CCD photometry of selected asteroids was carried out to check for possible cometary activity in them. To distinguish the asteroids with possible cometary activity from those of the main belt, each object of interest was observed in two filters; one centered on the C2 emission band at 5140A (90A bandpass) and the other centered on the nearby continuum at 4845A (65A bandpass). None of the observed asteroids appear to have any C2 emission.

Rajamohan, R.; Bhargavi, S. G.

1992-01-01

25

f-band narrowing in uranium intermetallics  

SciTech Connect

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

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

1987-01-01

26

Narrow-Linewidth Interwell THz Intersubband Emission.  

National Technical Information Service (NTIS)

Narrow-linewidth terahertz spontaneous emission resulting from interwell (or diagonal) intersubband transition from an electrically pumped multiple quantum-well (MQW) structure was observed. The center frequency of the emission peak is at 2.57 THz, and it...

B. Xu B. S. Williams M. Melloch Q. Hu

2000-01-01

27

Photonic crystal enhanced narrow-band infrared emitters  

NASA Astrophysics Data System (ADS)

We have experimentally and theoretically developed a unique thermally stimulated midinfrared source that emits radiation within a narrow range of wavelengths (??/?<=0.2). The emission wavelengths are defined by the periodicity of a metal coated silicon-air photonic crystal etched into the emitter surface. The lattice of the holes in the metal mediate the coupling of light into discrete surface plasmon states. This yields surfaces with spectrally nonuniform infrared reflection properties where over much of the IR 90+% of photons are reflected yet, in a narrow spectral region, 90% absorption is observed. Transfer matrix calculations simulate well the position and strength of the absorption features. This technology will afford tunable infrared emitters with high power in a narrow spectral band that are critical for sensing, spectroscopy, and thermophotovoltaic applications.

Pralle, M. U.; Moelders, N.; McNeal, M. P.; Puscasu, I.; Greenwald, A. C.; Daly, J. T.; Johnson, E. A.; George, T.; Choi, D. S.; El-Kady, I.; Biswas, R.

2002-12-01

28

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

29

Tissue characterization by using narrow band imaging  

NASA Astrophysics Data System (ADS)

NBI (Narrow Band Imaging) was first introduced in the market in 2005 as a technique enabling to enhance image contrast of capillaries on a mucosal surface(1). It is classified as an Optical-Digital Method for Image-Enhanced Endoscopy(2). To date, the application has widely spread not only to gastrointestinal fields such as esophagus, stomach and colon but also the organs such as bronchus and bladder. The main target tissue of NBI enhancement is capillaries. However, findings of many clinical studies conducted by endoscopy physicians have revealed that NBI observation enables to enhance more other structures in addition to capillaries. There is a close relationship between those enhanced structures and histological microstructure of a tissue. This report introduces the tissue microstructures enhanced by NBI and discusses the possibility of optimized illumination wavelength in observing living tissues.

Gono, Kazuhiro

2010-02-01

30

Electrical and Optical Properties of Narrow-Band Materials  

Microsoft Academic Search

The electrical and optical properties of materials which are characterized by narrow bands in the vicinity of the Fermi energy are discussed. For such materials, electronic correlations and the electron-phonon coupling must be considered explicitly. Correlations in f bands and in extremely narrow d bands can be handled in the ionic limit of the Hubbard Hamiltonian. It is shown that

David Adler; Julius Feinleib

1970-01-01

31

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

32

Fast, Narrow-Band Computer Model for Radiation Calculations  

Microsoft Academic Search

A fast, narrow-band computer model, FASTNB, which predicts the radiation intensity in a general nonisothermal and nonhomogeneous combustion environment, has been developed. The spectral absorption coefficients of the combustion products, including carbon dioxide, water vapor, and soot, are calculated based on the narrow-band model FASTNB provides an accurate calculation at reasonably high speed. Compared with Grosshandler's narrowband model, RADCAL, which

Zhenghua Yan; Göran Holmstedt

1997-01-01

33

Electronic structure and thermoelectric properties of narrow band gap chalcogenides  

Microsoft Academic Search

In recent years there have been a revival of interest in discovering and understanding the physical properties of novel thermoelectric (TE) systems with high figure of merit. These systems are primarily narrow band gap semiconductors. In this thesis, electronic structure calculations were carried out for several narrow band gap chalcogenide TE materials in order to understand their electronic and transport

Daniel Bilc

2005-01-01

34

Narrow band images of suspected cooling flow galaxies  

NASA Technical Reports Server (NTRS)

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

Deustua, Susana; Bothun, Greg

1990-01-01

35

High power narrow-band fiber-based ASE source.  

PubMed

In this paper we describe a high power narrow-band amplified spontaneous emission (ASE) light source at 1030 nm center wavelength generated in an Yb-doped fiber-based experimental setup. By cutting a small region out of a broadband ASE spectrum using two fiber Bragg gratings a strongly constrained bandwidth of 12±2 pm (3.5±0.6 GHz) is formed. A two-stage high power fiber amplifier system is used to boost the output power up to 697 W with a measured beam quality of M2?1.34. In an additional experiment we demonstrate a stimulated Brillouin scattering (SBS) suppression of at least 17 dB (theoretically predicted ~20 dB), which is only limited by the dynamic range of the measurement and not by the onset of SBS when using the described light source. The presented narrow-band ASE source could be of great interest for brightness scaling applications by beam combination, where SBS is known as a limiting factor. PMID:21369273

Schmidt, O; Rekas, M; Wirth, C; Rothhardt, J; Rhein, S; Kliner, A; Strecker, M; Schreiber, T; Limpert, J; Eberhardt, R; Tünnermann, A

2011-02-28

36

Fast, narrow-band computer model for radiation calculations  

SciTech Connect

A fast, narrow-band computer model, FASTNB, which predicts the radiation intensity in a general nonisothermal and nonhomogeneous combustion environment, has been developed. The spectral absorption coefficients of the combustion products, including carbon dioxide, water vapor, and soot, are calculated based on the narrow-band model. FASTNB provides an accurate calculation at reasonably high speed. Compared with Grosshandler`s narrow-band model, RADCAL, which has been verified quite extensively against experimental measurements, FASTNB is more than 20 times faster and gives almost exactly the same results.

Yan, Z.; Holmstedt, G. [Lund Univ. (Sweden). Dept. of Fire Safety Engineering

1997-01-01

37

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

38

Narrow-Band Inverted Homo-Heterojunction Avalanche Photodiode.  

National Technical Information Service (NTIS)

The patent application describes a narrow-band, inverted homo-heterojunction avalanche photodiode, configured in the shape of a mesa situated upon a substrate which is transparent to selected light energy wavelengths. The diode is inverted for operation s...

R. C. Eden

1977-01-01

39

The electronic structure of heavy fermions: Narrow temperature independent bands  

SciTech Connect

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

Arko, A.J.; Joyce, J.J.; Smith, J.L.; Andrews, A.B. [and others

1996-08-01

40

Narrow band imaging: application for early-stage gastrointestinal neoplasia.  

PubMed

Narrow-band imaging (NBI) is an imaging technique for endoscopy using optical filters to narrow the bandwidth of spectral transmittance. Through this narrow spectrum, NBI contrasts surface structure and microvascular architecture of various lesions. In this article we focus on the application of NBI for early-stage neoplasia in the esophagus, stomach and colon with a three-step strategy of endoscopic diagnosis: (i) the detection of abnormality; (ii) the differentiation between non-neoplasia and neoplasia; and (iii) staging for tumor extension and depth of invasion. PMID:24868598

Zhu, Ling Yin; Li, Xiao Bo

2014-05-01

41

Localized description of superconductivity in narrow-band metals  

Microsoft Academic Search

A localized description of superconductivity in narrow-band metals, proposed by Appel and Kohn, is applied to the calculation of the phonon-exchange vertex in three transition metals. The essence of this description is the formulation of the equation for the vertex function in the Wannier representation and the assumption of a contact interaction, in which the two electrons in a Cooper

A. Birnboim; H. Gutfreund

1974-01-01

42

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

43

Active Narrow-Band Vibration Isolation of Large Engineering Structures  

NASA Technical Reports Server (NTRS)

We present a narrow-band tracking control method using a variant of the Least Mean Squares (LMS) algorithm to isolate slowly changing periodic disturbances from engineering structures. The advantage of the algorithm is that it has a simple architecture and is relatively easy to implement while it can isolate disturbances on the order of 40-50 dB over decades of frequency band. We also present the results of an experiment conducted on a flexible truss structure. The average disturbance rejection achieved is over 40 dB over the frequency band of 5 Hz to 50 Hz.

Rahman, Zahidul; Spanos, John

1994-01-01

44

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

45

Novel structural flexibility identification in narrow frequency bands  

NASA Astrophysics Data System (ADS)

A ‘Sub-PolyMAX’ method is proposed in this paper not only for estimating modal parameters, but also for identifying structural flexibility by processing the impact test data in narrow frequency bands. The traditional PolyMAX method obtains denominator polynomial coefficients by minimizing the least square (LS) errors of frequency response function (FRF) estimates over the whole frequency range, but FRF peaks in different structural modes may have different levels of magnitude, which leads to the modal parameters identified for the modes with small FRF peaks being inaccurate. In contrast, the proposed Sub-PolyMAX method implements the LS solver in each subspace of the whole frequency range separately; thus the results identified from a narrow frequency band are not affected by FRF data in other frequency bands. In performing structural identification in narrow frequency bands, not in the whole frequency space, the proposed method has the following merits: (1) it produces accurate modal parameters, even for the modes with very small FRF peaks; (2) it significantly reduces computation cost by reducing the number of frequency lines and the model order in each LS implementation; (3) it accurately identifies structural flexibility from impact test data, from which structural deflection under any static load can be predicted. Numerical and laboratory examples are investigated to verify the effectiveness of the proposed method.

Zhang, J.; Moon, F. L.

2012-12-01

46

Composite polarons in ferromagnetic narrow-band metallic manganese oxides  

Microsoft Academic Search

Moving electrons accompanied by Jahn - Teller phonon and spin-wave clouds may form composite polarons in ferromagnetic narrow-band manganites. The ground-state and finite-temperature properties of such composite polarons are studied in the present paper. By using a variational method, it is shown that the energy of the system at zero temperature decreases with the formation of the composite polaron and

Liang-Jian Zou; H. Q. Lin; Qing-Qi Zheng

1997-01-01

47

Band gap narrowing of titanium dioxide by sulfur doping  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) doped with sulfur (S) was synthesized by oxidation annealing of titanium disulfide (TiS2). According to the x-ray diffraction patterns, TiS2 turned into anatase TiO2 when annealed at 600 degC. The residual S atoms occupied O-atom sites in TiO2 to form TiSingle_BondS bonds. The S doping caused the absorption edge of TiO2 to be shifted into the lower-energy region. Based on the theoretical analyses using ab initio band calculations, mixing of the S 3p states with the valence band was found to contribute to the band gap narrowing.

Umebayashi, T.; Yamaki, T.; Itoh, H.; Asai, K.

2002-07-01

48

Narrow-band Jovian kilometric radiation: A new radio component  

Microsoft Academic Search

We describe in new component of Jupiter's radio spectrum. This component emits in a very narrow bandwith (< or =40 kHz) near 100 kHz. Its waveform is a very smooth and gradual rise and subsequent fall in intensity over typically two hours. The emission is polarized with left-hand polarization associated with the Jovian northern magnetic hemisphere and righthand with the

M. L. Kaiser; M. D. Desch

1980-01-01

49

Improved full-spectrum k-distribution implementation for inhomogeneous media using a narrow-band database  

NASA Astrophysics Data System (ADS)

A new implementation to determine the correlated k values as used in full-spectrum correlated k-distribution methods for inhomogeneous media is presented, which conserves radiative emission and significantly improves the accuracy of the full-spectrum correlated k-distribution method in strongly inhomogeneous media. In addition, an update of a previous high-accuracy, compact narrow-band k-distribution database is given. The new narrow-band database utilizes the latest spectroscopy databases to ensure accuracy at elevated temperatures and pressures. Differences between the two versions of narrow-band k-distribution databases as a result of the change of spectroscopy databases are illustrated.

Cai, Jian; Modest, Michael F.

2014-07-01

50

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

51

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

52

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

53

Airborne observations of the infrared emission bands  

NASA Technical Reports Server (NTRS)

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 discussed. A new emission band at 5.2 microns, previously predicted for PAHs, was found in 33 sources; it also correlates with the 7.7 microns band. This extends the spectrum of narrow observed PAH features to 3.3, 5.2, 5.6, 6.2, 6.9, 7.7, 8.7, 11.3, and 12.7 microns. From the data the relative strengths of most of these bands are defined in three separate nebular environments: planetaries, H II regions, and reflection nebulae. The differences in the PAHs spectra in those environments are analyzed.

Cohen, M.; Bregman, J.; Witteborn, F. C.; Wooden, D. H.; Rank, D. M.; Demuizon, M. Jourdain; Allamandola, Louis J.; Tielens, Alexander G. G. M.

1989-01-01

54

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

55

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

Microsoft Academic Search

The shape of the bands for photon absorption and emission by the local constituents of a solid is governed mainly by processes involving many low-energy acoustic phonons. This applies not only to wide bands, such as those exhibited by F centers, but also to narrow ones, as those observed for infrared absorption by local vibration modes of U centers and

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

2008-01-01

56

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

57

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

2012-09-01

58

Narrow pass-band high power TWT amplifier  

SciTech Connect

At power levels exceeding the 100 MW level the spectrum of the output signal from a traveling wave tube amplifier contains a significant amount of power in frequencies other than the input frequency. The structure of the spectrum is determined by the noise in the system and the interference of the two waves bouncing due to finite reflections at the two ends of the waveguide. There are cases when the power in these selected frequencies is actually equal or even larger than in the initial frequency. Consequently, the device operates more like an oscillator than as an amplifier. In order to overcome this problem we have designed a narrow band periodic structure in which the electrons, whether they are bunched or not, can emit radiation only in a range of less than 50 MHz---in comparison to 1.5 GHz in the old structure. In this structure the group velocity is very low ([beta][sub [ital gr

Schaechter, L.; Nation, J.A. (Laboratory of Plasma Studies and School of Electrical Engineering, Cornell University, Ithaca, New York (United States))

1992-07-01

59

Generation of narrow-band photon pairs for quantum memory  

NASA Astrophysics Data System (ADS)

We demonstrate a narrow-band photon pair source on a rubidium (Rb) D 2 line (780 nm) using a periodical poled KTiOPO 4 crystal via a degenerate optical parametric oscillator far below threshold. The single longitudinal mode is selected by a spectral filtering cavity. The measured cross correlation between two photons shows that the generated photon has a linewidth of 21 MHz, which is comparable to the typical linewidth of an atomic-based quantum memory. The detected photon pair rate is about 2.7/s/MHz/mW. This system could be utilized for many applications in quantum information field, such as the storage and retrieval of a photon in Rb atomic ensemble and so on.

Wang, Fu-Yuan; Shi, Bao-Sen; Guo, Guang-Can

2010-07-01

60

PAU, a fully depleted mosaic imager with narrow band filters  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

61

Evolution of Narrow Band Spectra of Surface Gravity Waves  

NASA Astrophysics Data System (ADS)

It is well-known that a uniform train of surface gravity waves is unstable to the so- called Benjamin-Feir (BF) instability. The stability of a narrow band of Gaussian random wavetrains was considered by Alber and Saffman (1978), Alber (1978) and Crawford et al. (1980). For waves on deep water they found that the BF instability persists provided that the relative spectral width, x, of the wavenumber spectrum (in the main direction of wave propagation, x) is less than twice the average steepness, k0a, where k0 is the central wavenumber and a is the rms value of the amplitude. Here we compare these results with numerical simulations on the evolution of narrow band spectra in two and three dimensions. For deep water waves the results of Alber and Saffman (1978) and Alber (1978) are based on the Non-Linear Schrödinger equa- tion (NLS) which is the lowest order model equation (in the relative spectral width, and the wave steepness) taking into account both dispersion and nonlinearity. We have done simulations both with the NLS equation and with a modified NLS-type equation (MNLS) taking into account higher order terms in the relative bandwidth (Trulsen and Dysthe (1996), Trulsen et al. (2000)). The results of the simulations can be summarized as follows: The two dimensional simulations. In the NLS simulation the criterion x > 2 for suppression of the BF instability is verified. In the unstable case (x < 2 ) we find that the spectrum broadens symmetrically till it reaches a stable width. In the MNLS simulation the initially symmetric Gaussian shape of the spectrum does not persist, regardless of the initial spectral width. On the timescale ( 0)-1the spec- tral peak moves towards lower wavenumbers, with a steepening on the low- and a tail forming on the high frequency side. The three dimensional simulations. The 3d NLS simulations do not support the the- oretical results of Alber (1978) and Crawford et al. (1980). A considerable widening of the spectrum is seen almost regardless of the initial spectral width x in the main wave direction. The MNLS simulations still show an asymmetric development. There is a steepen- ing on the low frequency side and a tail growing on the high frequency side with a corresponding downshift of the spectral peak. The tail formation shows a power-law behavior |k|-p with p 2.5 corresponding to a -4 law of the frequency spectrum. The research was funded by the BeMatA program of the Research Council of Norway and by Norsk Hydro.

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

62

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

63

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

PubMed Central

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

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

2013-01-01

64

Electronic structure and thermoelectric properties of narrow band gap chalcogenides  

NASA Astrophysics Data System (ADS)

In recent years there have been a revival of interest in discovering and understanding the physical properties of novel thermoelectric (TE) systems with high figure of merit. These systems are primarily narrow band gap semiconductors. In this thesis, electronic structure calculations were carried out for several narrow band gap chalcogenide TE materials in order to understand their electronic and transport properties governing their TE characteristics. These calculations were performed within ab initio density functional theory (DFT) using full potential linearized augmented plane wave (FLAPW) method. Transport calculations were carried out using Boltzmann transport equations. For the binary chalcogenides Bi2Se3 and Bi 2Te3 I have studied the effect of quantum confinement (QC) created by the surfaces on their bulk electronic structure. In the presence of such confinement, surface states appear, which are a consequence of the strong influence of the interlayer bonding on the bulk electronic structure of these compounds. I find that in contrast to standard belief, there is an important covalent contribution to the interlayer bonding besides the Van der Waals contribution. (Bi2Te3)m(Sb2 Te3)n superlattices (SL) show very good TE properties at room temperature. To see how the electronic structure of Bi2Se3 and Bi2Te3 are affected by the formation of SL, I have investigated the electronic properties of (Bi 2Te3)m(Sb2Te 3)n SL as compared to those of Bi2 Se3 and Bi2Te3 bulk systems. We find that the formation of SL does not deteriorate the electronic transport properties along the cross plane direction. Complex ternary K2Bi8Se13 system shows great potential for superior TE performance. This compound forms in two distinct phases, alpha and beta. The beta-phase, which has two sites with K/Bi disorder, is a better TE. The calculations show that alpha-phase is an indirect band gap semiconductor. For the beta-phase, we find that the atoms at the "mixed sites" are very important in determining the electronic properties. The incorporation of the K/Bi mixed occupancy at the disordered sites is crucial for the semiconductor behavior. We also find a strong anisotropy in the hole and electron effective mass. Complex quaternary AgPbmSbTe2+ m (LAST-m) systems are excellent high temperature TE. These systems form in the rocksalt structure similar to PbTe where Ag and Sb occupy Pb sites. There are clear experimental evidences that LAST-m systems exhibit microscopic inhomogeneities rich in Ag-Sb embedded into a PbTe matrix. Our calculations show that resonant states appear near the PbTe band gap. The common feature of all Ag-Sb arrangements is that they have a more enhanced density of states (DOS) near the gap as compared to PbTe. To see how these features in the DOS affect the transport properties I have carried out transport calculations in PbTe and LAST-m systems. The results for PbTe show that the temperature dependence of the effective mass md is very important in order to have good agreement with experiment. The LAST-m systems show an enhancement of the power factor (S 2sigma) relative to PbTe. But this enhancement is not large enough to explain the experimentally observed ZT. This suggests that the reduction in the thermal conductivity caused by Ag-Sb nanostructures in PbTe matrix may be significant.

Bilc, Daniel

65

Narrow-band imaging evaluation of bladder tumors.  

PubMed

Narrow-band imaging (NBI) is a novel optical method designed to enhance visual detection of bladder tumors over conventional white-light imaging (WLI) cystoscopy. Current experience with NBI cystoscopy in evaluating and treating non-muscle-invasive bladder tumors is reviewed. A comprehensive literature search was conducted including all published studies and abstracts investigating NBI cystoscopy in patients with bladder cancer. Comprehensive cystoscopic images are provided to illustrate differences between NBI and WLI cystoscopy. Early experience suggests that NBI cystoscopy detects more bladder tumors than does WLI cystoscopy, and NBI-assisted fulguration and transurethral resection (TUR) appear to result in fewer tumor recurrences. Questions remain, however, such as the following: Does NBI cystoscopy detect high-grade tumors, such as carcinoma in situ, that are missed by WLI cystoscopy? Would false positives lead to an unaccepted number of negative biopsies? And how might observer bias skew results? In addition, a major drawback of current studies is that the quality of cystoscopy and TUR by individual surgeons has not been addressed. Although clinical trials are just beginning, NBI cystoscopy holds promise that this new optical method may improve visualization of bladder tumors over conventional WLI cystoscopy. Further prospective and comparative trials are required to determine whether NBI will play a role in evaluating and treating urothelial tumors in individual patients. PMID:24652533

Herr, Harry W

2014-04-01

66

Narrow-band ELF events observed from South Pole Station  

NASA Astrophysics Data System (ADS)

Extremely Low Frequency (ELF) waves are typically in the range of 3 Hz - 3 kHz and can play a role in acceleration and pitch-angle scattering of energetic particles in the radiation belts. Observations of a not uncommon, but not well studied ELF phenomenon are presented with ground-based data from South Pole Station. The narrow-band waves last approximately one or two minutes maintaining bandwidth over the course of the event, begin around 100 Hz, decrease to about 70 Hz, and typically show a higher frequency harmonic. The waves have only been documented at four locations - Heacock, 1974 (Alaska); Sentman and Ehring, 1994 (California); Wang et al, 2005 and Wang et al, 2011 (Taiwan); and Kim et al, 2006 (South Pole). The waves observed at the South Pole are not detected when the Sun drops below a 10 degree elevation angle, which is not true for the other locations. We extend the study of Kim et al, 2006, and explore possible generation mechanisms including sunlit ionosphere and ion cyclotron wave modes, as well as correspondence with energetic particle precipitation.

Heavisides, J.; Weaver, C.; Lessard, M.; Weatherwax, A. T.

2012-12-01

67

Narrow band noise response of a Belleville spring resonator.  

PubMed

This study of nonlinear dynamics includes (i) an identification of quasi-steady states of response using equivalent linearization, (ii) the temporal simulation of the system using Heun's time step procedure on time domain analytic signals, and (iii) a laboratory experiment. An attempt has been made to select material and measurement parameters so that nearly the same systems are used and analyzed for all three parts of the study. This study illustrates important features of nonlinear response to narrow band excitation: (a) states of response that the system can acquire with transitions of the system between those states, (b) the interaction between the noise source and the vibrating load in which the source transmits energy to or draws energy from the load as transitions occur; (c) the lag or lead of the system response relative to the source as transitions occur that causes the average frequencies of source and response to differ; and (d) the determination of the state of response (mass or stiffness controlled) by observation of the instantaneous phase of the influence function. These analyses take advantage of the use of time domain analytic signals that have a complementary role to functions that are analytic in the frequency domain. PMID:23967926

Lyon, Richard H

2013-09-01

68

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

69

The Narrow and Variable Emission Lines in NGC 4151  

Microsoft Academic Search

Two narrow emission lines at 1518A and 1594A respectively (hereafter called L1 and L2) with intensities varying on time scales of day(s) have been found in the UV spectrum of NGC 4151. These lines are too narrow to be emitted by the entire broad line region. Therefore, regardless of their identifications, they must come from localized regions with a special

Marie-Helene Ulrich

1991-01-01

70

The narrow band of electronic states localized at the interfaces of superlattices  

Microsoft Academic Search

Within the framework of tight-binding theory the author has found a class of superlattices that possess a narrow band of electronic states localized at interfaces. He suggests that, if the electron-phonon interaction is small enough, it could preserve the existence of the narrow band and lead to a superconducting state formed by Cooper pairs of heavy electrons localized at interfaces.

V. L. Golo

1991-01-01

71

A FAST SPECTRAL APPROXIMATION OF NARROW-BAND MODEL FOR THERMAL RADIATION CALCULATION  

Microsoft Academic Search

A fast spectral approximation of a narrow-band computer model is proposed for prediction of thermal radiation in a generally nonisothermal and nonhomogeneous combustion environment. The approximation is made by assuming each discretized spatial element along a line of sight to be locally “gray” within each small narrow-band spectrum interval. For each spatial element, the local equivalent spectral absorption coefficient of

Z. H. Yan

2004-01-01

72

Detection and Initial Tracking of Narrow-Band Signals in Noise.  

National Technical Information Service (NTIS)

Suppose a signal is observed for a time Tsec. It consists of white Gaussian noise and possibly the presence of one or more sine waves or narrow-band signals. It is desired to decide whether any sine waves or narrow-band signals are present; If they are pr...

G. W. Lank

1973-01-01

73

Ponderomotive narrow continuum (NCp) component in stimulated electromagnetic emission spectra  

Microsoft Academic Search

We present experimental results concerning the ponderomotive narrow continuum (NCp) in stimulated electromagnetic emission spectra, generated in the ionospheric F region plasma by a powerful O mode electromagnetic wave. It is found that the generation of the NCp is determined by the development of the parametric decay instability in the initial stage of the interaction of the HF pump wave

V. L. Frolov; E. N. Sergeev; G. P. Komrakov; P. Stubbe; B. Thidé; M. Waldenvik; E. Veszelei; T. B. Leyser

2004-01-01

74

Narrow-band EUV multilayer coating for the MOSES sounding rocket  

NASA Astrophysics Data System (ADS)

The Multi-order Solar EUV Spectrograph (MOSES) is a slitless spectrograph designed to study solar He II emission at 303.8 Å (1 Å = 0.1 nm), to be launched on a sounding rocket payload. One difference between MOSES and other slitless spectrographs is that the images are recorded simultaneously at three spectral orders, m = -1, 0, +1. Another is the addition of a narrow-band multilayer coating on both the grating and the fold flat, which will reject out-of-band lines that normally contaminate the image of a slitless instrument. The primary metrics for the coating were high peak reflectivity and suppression of Fe XV and XVI emission lines at 284 Å and 335 Å, respectively. We chose B4C/Mg2Si for our material combination since it provides excellent peak reflectivity and rejection of out-of-band wavelengths. Measurements of witness flats at NIST indicate the peak reflectivity at 303.8 is 39.0% for a 15 bilayer stack, while suppression ranges from 7.5x to 12.9x at 284 Å and from 3.4x to 15.1x at 335 Å for the individual reflections in the optical path. We present the results of coating the MOSES flight gratings and fold flat, including the spectral response of the fold flat and grating as measured at NIST's SURF III and Brookhaven's X24C beamline, respectively.

Owens, Scott M.; Gum, Jeffery S.; Tarrio, Charles; Grantham, Steven; Dvorak, Joseph; Kjornrattanawanich, Benjawan; Keski-Kuha, Ritva; Thomas, Roger J.; Kankelborg, Charles C.

2005-08-01

75

Ultra-narrow-band light dissipation by a stack of lamellar silver and alumina  

NASA Astrophysics Data System (ADS)

An ultra-narrow band absorber consisting of continuous silver and alumina films is investigated. Owing to Fabry-Pérot resonance and silver's inherent loss, an ultra-narrow spectral range of light can be entirely trapped in the structure. By varying thicknesses of metallic and dielectric films, absorption peak shifts in visible and near-infrared regions. When two such metal-insulator-metal stacks are cascaded, experimental results show that an ultra-narrow absorption bandwidth of 7 nm is achieved, though theoretical results give that of 2 nm. Features of high-efficiency and ultra-narrow band absorption have huge potential in optical filtering, thermal emitter design, etc.

Zhao, Ding; Meng, Lijun; Gong, Hanmo; Chen, Xingxing; Chen, Yiting; Yan, Min; Li, Qiang; Qiu, Min

2014-06-01

76

A narrow conduction band in YBa 2Cu 3O 7-?  

NASA Astrophysics Data System (ADS)

LDA band-structure calculations of YBa 2Cu 3O 7-? show wide bands (of several eV) spanning EF. However, experiments, and especially transport measurements, contradict this and indicate the presence of a narrow conduction band (about a tenth of an eV wide).

Genossar, J.; Fisher, B.; Ashkenazi, J.

1989-12-01

77

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

78

Square-Patterned Narrow-Band Infrared Emitter for Filter Less Infrared Gas Sensor  

NASA Astrophysics Data System (ADS)

In this study, we proposed a square-patterned narrow-band infrared (IR) emitter for a filterless IR gas sensor. As a new method of infrared gas sensing compared with previous research, it is proposed that a narrow-band IR emitter fabricated by micro-electro-mechanical-systems (MEMS) technology be applied to analyze dimethyl ether [(CH3)2O] gas. The proposed IR emitter consists of a TiN/SiO2/TiN trilayer, where the top TiN layer is square-patterned. The IR emitter radiates emissions at wavelengths of 7.68 and 7.88 ?m in accordance with the type of sample. The wavelength can be adjusted by changing the period of the surface pattern. The proposed IR emitter shows a narrow peak width (??/?) of 0.16--0.23. The apparatus for gas detection consists of the proposed IR emitter, a gas cell and a bolometric IR sensor based on amorphous SiGe:H. The change in electrical resistance of the gas detector during inflow of (CH3)2O gas, which has a fingerprint wavelength in the range of 7.6--10 ?m, was much smaller than that during inflow of CO2 gas, because (CH3)2O absorbed its corresponding wavelength in the range of 7.6--10 ?m. Because of the concentrated radiation of the IR emitter at the wavelength of 7.88 ?m, (CH3)2O absorbs relatively large amounts of infrared energy. The electrical resistance of the gas detector changed linearly as the concentration of (CH3)2O gas increased in the range of 0 to 500 ppm.

Song, Jun Tae; Park, Joong Hee; Lee, June Kyoo; Choi, Ju Chan; Kong, Seong Ho

2012-06-01

79

Narrow band microwave radiation from a biased single-Cooper-pair transistor  

NASA Astrophysics Data System (ADS)

We have spectroscopically measured narrow-band microwave radiation emitted from a single-Cooper-pair transistor (SCPT) electrometer biased in its sub-gap region. This radiation was detected by photon-assisted quasiparticle tunneling in a nearby SCPT, in a configuration that closely mimics a qubit-electrometer integrated circuit. In addition to the usual Josephson radiation generated by the electrometer, we also find emission lines whose frequency depend on both the gate charge and bias voltage of the electrometer, and attribute these lines to radiative Cooper-pair transport processes in the biased transistor. Our results suggest that the dissipative operation of an SCPT electrometer, when used as a qubit readout device, may severely disrupt the system it attempts to measure. This radiative coupling between Josephson charge devices, which dominates when coupling in the charge channel is negligible, may impose design constraints on a large scale multi-qubit quantum computer.

Naaman, Ofer; Aumentado, José.

2007-03-01

80

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

NASA Technical Reports Server (NTRS)

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

Patterson, James D.

1991-01-01

81

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

PubMed

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

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

2014-01-01

82

Narrowing the locking band in a laser with nonlinear absorption  

NASA Astrophysics Data System (ADS)

The use of the competing resonances of ring lasers to eliminate frequency locking which imposes a fundamental limitation on the measurement of very low rotational velocities is investigated. It is shown that the width of the locking band is not a constant property and is determined primarily by the nonlinear coupling of the waves because of their reflection from structural elements of the resonator and by the nonlinear interaction of the traveling waves in the laser medium. Since the terms describing this interaction have different signs in amplifying and absorbing media, the nonlinear wave coupling and also the value of the locking band width decrease substantially at frequencies where the nonlinear absorption is most apparent (i.e., near the central frequency of the absorption line). In this situation, the primary contribution to the width of the locking band is eliminated.

Danileiko, M. V.; Nedavnii, A. P.

1981-07-01

83

Electronic contribution to the thermal conductivity of narrow band gap semiconductors-effect of non-parabolicity of bands  

Microsoft Academic Search

A theoretical calculation of the electronic contribution to the thermal conductivity ( lambda e) of narrow band gap semiconductors is presented which takes into account the non-parabolic nature and multivallied structure of the energy bands including intervalley scattering. The analysis indicates a significant reduction in the Lorenz factor L and the ratio of electronic and lattice thermal conductivities ( lambda

C. M. Bhandari; D. M. Rowe

1985-01-01

84

Phase plane for narrow band random excitation of a Duffing oscillator  

Microsoft Academic Search

The response of a Duffing oscillator to narrow band random excitation is considered. It is shown that multiple values of the response can occur at some frequencies for very narrow excitation bandwidths, but these reduce to a single value as the bandwidth is increased. Time histories of quantities such as mean square displacement are obtained from the time dependent Fokker

H. G. Davies; D. Nandlall

1986-01-01

85

Narrow-band EUV Multilayer Coating for the MOSES Sounding Rocket  

NASA Technical Reports Server (NTRS)

The Multi-order Solar EUV Spectrograph (MOSES) is a slitless spectrograph designed to study solar He II emission at 303.8 Angstroms, to be launched on a sounding rocket payload. One difference between MOSES and other slitless spectrographs is that the images are recorded simultaneously at three spectral orders, m = -1,0, +l. Another is the addition of a narrow-band multilayer coating on both the grating and the fold flat, which will reject out-of-band lines that normally contaminate the image of a slitless instrument. The primary metrics f a the mating were high peak reflectivity and suppression of Fe XV and XVI emission lines at 284 Angstroms and 335 Angstroms, respectively. We chose B4C/Mg2Si for our material combination since it provides better values for all three metrics together than the other leading candidates Si/Ir, Si/B4C or Si/SiC. Measurements of witness flats at NIST indicate the peak reflectivity at 303.6 is 38.5% for a 15 bilayer stack, while the suppression at 284 Angstroms, is 4.5x and at 335 Angstroms is 18.3x for each of two reflections in the instrument. We present the results of coating the MOSES flight gratings and fold flat, including the spectral response of the fold flat and grating as measured at NIST's SURF III and Brookhaven's X24C beamline.

Owens, Scott M.; Gum, Jeffery S.; Tarrio, Charles; Dvorak, Joseph; Kjornrattanawanich, Benjawan; Keski-Kuha, Ritva; Thomas, Roger J.; Kankelborg, Charles C.

2005-01-01

86

Electron-phonon interaction and Boltzmann equation in narrow-band semiconductors  

Microsoft Academic Search

Interaction of electrons or holes in narrow energy bands with both acoustic and polar phonons is investigated. Based upon\\u000a a graphical expansion of the electron Green's function and of the transport vertex function, a Boltzmann equation is derived,\\u000a which includes one-phonon and simultaneous two-phonon scattering. The general results are applied to a one-dimensional model\\u000a of a narrow-band system.

J. Schnakenberg

87

Scaling of Coulomb pseudo-potential in narrow-band superconductors  

Microsoft Academic Search

The standard Eliashberg theory is extended to incorporate the narrow-band effects, that is, the vertex corrections and frequency dependence of the effective interaction between electrons. From the extended Eliashberg equation, the Coulomb pseudo-potential ?* is extracted. It is shown that even for narrow-band superconductors, where the Fermi energy ?F is comparable with the phonon frequency ?ph, the Coulomb pseudo-potential is

Tae-Ho Park; Han-Yong Choi

2001-01-01

88

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

Microsoft Academic Search

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

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

2009-01-01

89

Narrow band, large angular width resonant reflection from a periodic high index grid at terahertz frequency.  

PubMed

The property of a thin silicon membrane with periodic air slits of definite depth and width to exhibit under normal incidence a close to 100% ultra-narrow band reflection peak is demonstrated experimentally in the terahertz frequency range on a single-crystal silicon grid fabricated by submillimeter microsystem technology. An analysis based on the true modes supported by the grid reveals the nature of such resonances and permits to sort out those exhibiting ultra-narrow band. PMID:23263043

Parriaux, Olivier; Kämpfe, Thomas; Garet, Frédéric; Coutaz, Jean-Louis

2012-12-17

90

Searching for narrow-band oscillations in solar flares in the presence of frequency-dependent noise  

NASA Astrophysics Data System (ADS)

A common feature of solar flare emission is the appearance of short timescale fluctuations, often interpreted in terms of oscillatory signatures, and often referred to as quasi-periodic pulsations (QPPs) or quasi-periodic oscilations (QPOs). These fluctuations are an important diagnostic of solar plasma, as they are linked to the flare reconnection and particle acceleration sites. However, it has recently become clear that solar flare time series, like many astrophysical objects, are often dominated by frequency-dependent 'red' noise, rather than white noise. This frequency-dependent red-noise is commonly not taken into account when analyzing flare time-series for narrow-band oscillations. We demonstrate the application of a Bayesian method of searching for narrow-band oscillations in flares (based on Vaughan 2010) that fully accounts for frequency-dependent noise. We apply this method to the recent flares of 2011 February 15 and 2011 June 7, utilizing high-cadence EUV and X-ray data from the Proba-2/LYRA and Fermi/GBM instruments. While emphasizing that the observed fluctuations are a very real effect, we show that the emission from the selected events can be well described by a frequency-dependent noise model, without the need to invoke an explicit oscillatory mechanism. This presents a challenge to our current understanding of flare fluctuations, and suggests that narrow-band oscillations in flare emission may be much less prevalent than previously believed.

Inglis, Andrew; Ireland, Jack

2014-06-01

91

NICMOS Narrow-band Images of OMC-1  

NASA Technical Reports Server (NTRS)

We present images of a 90in. x 90in. field centered on BN in OMC-1, taken with the Near-Infrared Camera and MultiObject Spectrograph (NICMOS) aboard the Hubble Space Telescope. The observed lines are H2 1-0 S(l), Pa, [FeII] 1.64 pm, and the adjacent continua. The region is rich in interesting structures. The most remarkable are the streamers or "fingers" of H2 emission which extend from 15in. to 50in. from IRc2, seen here in unprecedented detail. Unlike the northern H2 fingers, the inner fingers do not exhibit significant [FeII] emission at theirdips, which we suggest is due to lower excitation. These observations also show that the general morphology of the Pa and [FeII] emission (both imaged for the first time in this region) bears a striking resemblance to that of the Ha and [SII] emission previously observed with WFPC2. This implies that these IR and optical lines are produced by radiative excitation on the surface of the molecular cloud. The Pa morphology of HH 202 is also very similar to its H a and [OIII] emission, again suggesting that the Pa in this object is photo-excited by the Trapezium, as has been suggested for the optical emission. We find evidence of shock-excited [FeII] in HH 208, where it again closely follows the morphology of [SII]. There is also H2 coincident with the [SII] and [FeII] emission, which may be associated with HH 208. Finally, we note some interesting continuum features: diffuse "tails" trailing from IRc3 and IRc4, more extensive observations of the "crescent" found by Stolovy, et al. (1998), and new observations of a similar oval object nearby. We also find a "V"-shaped region which may be the boundary of a cavity being cleared by IRc2.

Schultz, Angela S. B.; Colgan, Sean W. J.; Erickson, E. F.; Kaufman, M. J.; Hollenbach, D. J.; O'Dell, C. R.; Young, E. T.; Chen, H.

1998-01-01

92

Tracking photosynthetic efficiency with narrow-band spectroradiometry  

NASA Technical Reports Server (NTRS)

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

Gamon, John A.; Field, Christopher B.

1992-01-01

93

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

94

Narrow-band electrons in transition-metal oxides  

Microsoft Academic Search

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

John B. Goodenough

1967-01-01

95

Polaron Theory in Wide and Narrow Electron Bands  

Microsoft Academic Search

The polaron band theory of Lee, Low and Pines is extended beyond the effective mass approximation to a general form of the electron-phonon interaction within two different self-consistent schemes. In the first one a variational Bloch state depending on the polaron crystalline momentum is used to study polaron features taking into account umklapp processes. In particular, the self-energy and the

G. Iadonisi; V. Cataudella; D. Ninno

1997-01-01

96

Numerical Modeling of Narrow Band Soft X-ray Sources.  

National Technical Information Service (NTIS)

A model has been developed for calculating x-ray line emission from spherical plasmas. This method has been applied to an aluminum target, and the results are in good agreement with previous experimental work. The total energy, summed over all lines, as w...

R. J. Barker

1988-01-01

97

Broad- and Narrow-Band Wide-Field Imaging with pODI  

NASA Astrophysics Data System (ADS)

We present preliminary results of two distinct "science verification" observing programs that make use of the pODI instrument on the WIYN 3.5m telescope. This new camera covers a ~0.2 square degree field of view, has a fine pixel scale (0.11"/pixel), and delivers excellent image quality across the entire one-degree field. The first program consisted of observations of an extremely low HI-mass object to search for an optical counterpart (using gri filters) and signs of current star formation (using an H? filter). This object was detected in 21-cm HI emission by the ALFALFA survey and appears as a blue low-surface-brightness galaxy in our deep observations. Second, we have used multiple narrow-band filters to carry out wide field surveys for emission-line sources at various redshifts. We surveyed fields with existing spectroscopic follow-up (COSMOS, DEEP2) and also new fields to detect previously unknown emission-line sources at high redshift. Finally, we demonstrate our use of the ODI Pipeline Portal and Archive system in customizing the reduction and performing some of the data analysis in these projects.

Salzer, John J.; Janowiecki, S.

2013-06-01

98

Pilot-aided modulation for narrow-band satellite communications  

NASA Technical Reports Server (NTRS)

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

Saulnier, Gary J.; Rafferty, William

1988-01-01

99

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

100

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

2013-10-01

101

Deconvolving Contributions to the Narrow Emission-Line Spectra of Narrow-Line Seyfert 1s  

NASA Astrophysics Data System (ADS)

We present a continuation of our study of ground-based spectra of a sample of 12 Narrow-Line Seyfert 1s (NLSy1s), obtained using the 1.5m telescope at CTIO. Previously, we had found similar emission line ratios in both NLSy1s and Broad-Line Seyfert 1s (BLSy1s), which suggests similar ionizing continua, although we noted that low-ionization lines, such as [O I] 6300A and such as [S II] 6716,6731A may be somewhat weaker in NLSy1s. Based on photo-ionization modeling, the spectra from both types must include a strong contribution from dense, highly ionized gas in the inner narrow-line region (NLR), as has been noted in the literature. Notably, we find that the average [O III] 5007A/[OII] 3727A ratio is ~ 3.5 in NLSy1s, as compared to ~ 6.5 in a similar-sized sample of BLSy1s, consistent with a strong contribution from star-formation in the former. It is unclear whether star-formation is more prevalent in NLSy1s, suggesting a unique stage in the evolution of the AGN, or whether they tend to lack an extended NLR, which overwhelms any contribution from star-formationand may be due to the orientation of the AGN with the host galaxy.

Kraemer, Steven B.; Crenshaw, D. M.; Schmitt, H. R.; Dietrich, M.

2014-01-01

102

The relationship between rape biomass and narrow-band vegetation indices  

NASA Astrophysics Data System (ADS)

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

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

2004-11-01

103

Broadband and narrow band light coupling for QWIPs  

NASA Astrophysics Data System (ADS)

In this work, we will present a detailed study on the corrugated coupling scheme, which uses optical reflection at the angled sidewalls. In particular, we have investigated, both theoretically and experimentally, corrugated quantum well infrared photodetectors (QWIPs) with different cover materials over a wide range of spectral regime. We found that the coupling is insensitive to the wavelength but depends strongly on the optical properties of the cover material. We will also present the results of C-QWIP focal plane arrays (FPA) characterized so far. An important advantage of the corrugated coupling is its scalability to small pixel size. Based on one corrugation per pixel geometry, we have fabricated a 1024 × 1024 C-QWIP FPA with 99.5% connectivity. With the corrugated coupling geometry, many application restrictions on QWIPs can be eliminated. We will further show that the lack of normal incident absorption in QWIPs can actually be an advantage. It allows one to manipulate the absorption characteristics of QWIPs through different optical coupling structures and creates new detector functionality. The present example is an infrared spectrometer. It consists of a linear array of quantum grid infrared photodetector (QGIP) elements. Each QGIP element shares the same QWIP material but has different grid geometry. The QWIP is made of broadband materials such as the binary superlattices to give an extremely broadband (˜10 ?m) absorption. The structure of the grid, on the other hand, determines the specific wavelength to detect at each detector element in the array. In the QGIP spectrometer, detectors with different line widths will detect different wavelengths simultaneously, thus yielding the emission spectrum of an object. A collection of QGIP spectrometers can form an adaptive FPA.

Choi, K. K.; Lin, C. H.; Leung, K. M.; Tamir, T.; Mao, J.; Tsui, D. C.; Jhabvala, M.

2003-10-01

104

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

105

Soft x-ray narrow-band laser plasma sources for nanotechnology  

Microsoft Academic Search

The emission from laser produced plasma has been employed as a source of soft X-ray radiation for nanotechnology. By incorporating high Z elements into low Z solid hosts, targets have been fabricated which, when illuminated with high power Nd:YAG laser pulses, emit a significant proportion of the incident energy in a narrow wavelength region, with reduced continuum emission in the

Ronan Faulkner; Gerard D. O'Sullivan; Dave O'Reilly; Padraig Dunne

2000-01-01

106

Application of narrow-band television to industrial and commercial communications  

NASA Technical Reports Server (NTRS)

The development of narrow-band systems for use in space systems is presented. Applications of the technology to future spacecraft requirements are discussed along with narrow-band television's influence in stimulating development within the industry. The transferral of the technology into industrial and commercial communications is described. Major areas included are: (1) medicine; (2) education; (3) remote sensing for traffic control; and (5) weather observation. Applications in data processing, image enhancement, and information retrieval are provided by the combination of the TV camera and the computer.

Embrey, B. C., Jr.; Southworth, G. R.

1974-01-01

107

Motional Narrowing and Ergodic Bands in Excited Superdeformed States of Hg194  

NASA Astrophysics Data System (ADS)

The E?-E? coincidence spectra from the electromagnetic decay of excited superdeformed states in Hg194 reveal surprisingly narrow ridges, parallel to the diagonal. A total of 100 150 excited bands are found to contribute to these ridges, which account for nearly all the unresolved E2 decay strength. Comparison with theory suggests that these excited bands have many components in their wave functions, yet they display remarkable rotational coherence. This phenomenon can be explained in terms of the combination of shell effects and motional narrowing.

Lopez-Martens, A.; Døssing, T.; Khoo, T. L.; Matsuo, M.; Herskind, B.; Lauritsen, T.; Carpenter, M. P.; Janssens, R. V. F.; Hackman, G.; Lee, I.-Y.; Macchiavelli, A. O.; Vigezzi, E.; Yoshida, K.

2008-03-01

108

Low-frequency narrow-band acoustic filter with large orifice  

NASA Astrophysics Data System (ADS)

Conventional means of attenuating airborne sound usually require blocking the air medium with a solid material. By exploiting properties of membrane-type acoustic metamaterials (MAMs), we demonstrate large transmission loss to be achievable across a sizable orifice through which air can freely flow. We find that interaction of resonating field of the MAMs with the continuous sound field passing through the orifice is responsible for such phenomenon. The narrow-band characteristic of this effect can be used for acoustic filtering of noise with a particular narrow frequency band.

Ma, Guancong; Yang, Min; Yang, Zhiyu; Sheng, Ping

2013-07-01

109

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

PubMed Central

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

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

2014-01-01

110

Performance of WCDMA1900 in the presence of uncoordinated narrow-band GSM interference  

Microsoft Academic Search

This paper studies the performance of WCDMA in the FCC PCS (1900 MHz) band in the presence of an uncoordinated adjacent narrow-band GSM interferer. The effect of the interference from GSM to WCDMA is evaluated assuming a 2×5-MHz spectrum allocation for WCDMA. These studies are based on computer simulations, utilising cell site configuration based on real-world market designs. The main

Harri Holma; Fabricio Velez

2002-01-01

111

Narrow-Band Photometry of Red Supergiants in the Small Magellanic Cloud  

Microsoft Academic Search

A set of 36 red supergiants belonging to the Small Magellanic Cloud have been observed on a six-color narrow-band photometric system that measures continuum points and bands of TiO and CN, all in the near-infrared. The TiO--based spectral types range from

R. F. Wing; K. M. Walker; E. Costa; M. L. Houdashelt; D. J. MacConnell

2003-01-01

112

PRINCIPAL RESPONSE OF DUFFING OSCILLATOR TO COMBINED DETERMINISTIC AND NARROW-BAND RANDOM PARAMETRIC EXCITATION  

Microsoft Academic Search

The principal resonance of a Duffing oscillator to combined deterministic and narrow-band random parametric excitations is investigated. In particular, the case in which the parametric terms share close frequencies is examined. The method of multiple scales is used to determine the equations of modulation of amplitude and phase. The behavior, stability and bifurcation of steady state response are studied by

H. Rong; W. Xu; T. Fang

1998-01-01

113

Appearance of enhanced tissue features in narrow-band endoscopic imaging.  

PubMed

This study was performed to examine the usefulness of medical endoscopic imaging utilizing narrow-band illumination. The contrast between the vascular pattern and the adjacent mucosa of the underside of the human tongue was measured using five narrow-band illuminations and three broadband illuminations. The results demonstrate that the pathological features of a vascular pattern are dependent on the center wavelength and the bandwidth of illumination. By utilizing narrow-band illumination of 415+/-30 nm, the contrast of the capillary pattern in the superficial layer was markedly improved. This is an important benefit that is difficult to obtain with ordinary broadband illumination. The appearances of capillary patterns on color images were evaluated for three sets of filters. The narrow, band imaging (NBI) filter set (415+/-30 nm, 445+/-30 nm, 500+/-30 nm) was selected to achieve the preferred appearance of the vascular patterns for clinical tests. The results of clinical tests in colonoscopy and esophagoscopy indicated that NBI will be useful as a supporting method for observation of the endoscopic findings of early cancer. PMID:15189095

Gono, Kazuhiro; Obi, Takashi; Yamaguchi, Masahiro; Ohyama, Nagaaki; Machida, Hirohisa; Sano, Yasushi; Yoshida, Shigeaki; Hamamoto, Yasuo; Endo, Takao

2004-01-01

114

Comparison of narrow-band OFDM PLC solutions and I-UWB modulation over distribution grids  

Microsoft Academic Search

To support the requirements of smart grids (SGs) applications, telecommunication industries and standardization organizations have proposed to use narrow-band (NB) orthogonal frequency division multiplexing (OFDM) based solutions over power line communications (PLCs) networks. Among these solutions, the most important are the PoweRline Intelligent Metering Evolution (PRIME), the ERDF G3-PLC, and the G3-FCC.

Andrea M. Tonello; Salvatore D'Alessandro; Fabio Versolatto; Carlo Tornelli

2011-01-01

115

The Effect of Polarons on the Conductivity of the Narrow-Band Hubbard Chain.  

National Technical Information Service (NTIS)

We consider a half-filled, narrow band Hubbard chain with Holstein-type electron-phonon coupling to a set of intramolecular vibrational modes. We allow for dispersion in the vibrational spectrum and show, in the limit of zero temperature, that contrary to...

C. F. Coll G. Beni

1974-01-01

116

Narrow bands and electronic structure in unconventional high- T C superconductors  

Microsoft Academic Search

Electronic structure details play a marginal role in the superconductive properties of conventional superconductors. Electronic energies are by far the most important in these materials and the only relevant electronic parameter, with respect to superconductivity, is essentially the density of states N(0). Cooper oxides and fullerene compounds are characterized by narrow band dispersions and by electronic structures of hundreds meV.

E. Cappelluti; C. Grimaldi; L. Pietronero; S. Strässler

2002-01-01

117

Band narrowing and susceptibility enhancement by a quadratic electron-phonon interaction  

Microsoft Academic Search

It is shown that a quadratic electron-phonon interaction leads, under certain conditions, to temperature-dependent band narrowing and an inverse lifetime quadratic in the phonon occupation numbers. These explain the prominent metallic properties of organic metals of the TTF-TCNQ family, in particular the enhancement of the magnetic susceptibility.

O. Entin-Wohlman; H. Gutfreund; M. Weger

1985-01-01

118

Search for neutrino oscillations at the AGS with the narrow band beam  

SciTech Connect

We have taken neutrino data with the Narrow Band Beam (NBB) at Brookhaven National Laboratory (BNL) in the summer and fall of 1985. We are in the process of completing the analysis of the NBB data. In this paper we present preliminary results of this analysis. We observe an anomalous appearance of electron neutrinos above the expected background. 3 refs., 16 figs., 3 tabs.

Chi, C.; Kondakis, N.; Lee, W.; O'Brien, E.; O'Halloran, T.; Reardon, K.; Salman, S.; Blumenfeld, B.; Chichura, L.; Chien, C.Y.

1987-01-01

119

Narrow band coronographic imaging of the bipolar nebula around the LBV R127  

NASA Technical Reports Server (NTRS)

New high resolution narrow band coronographic images of the R127 nebula have been recently obtained. The nebula displays a bipolar morphology and is similar in appearance to the nebula around AG Carinae. The observations improve the values for the linear dimensions (1.9 x 2.2 pc) and yield an estimated nebular mass of 3.1 solar mass.

Clampin, Mark; Nota, Antonella; Golimowski, David A.; Leitherer, Claus

1992-01-01

120

Usefulness of Magnifying Narrow-Band Imaging Endoscopy in the Helicobacter pylori-Related Chronic Gastritis  

Microsoft Academic Search

Combining the narrow-band imaging (NBI) system and magnifying endoscopy allows simple and clear visualization of microscopic structures of the superficial mucosa and its capillary patterns, which may be useful for precise endoscopic diagnosis in the gastrointestinal tract, being more closely to histopathological diagnosis. In the non-neoplastic gastric mucosa, there have been reports showing a potential usefulness of magnifying NBI for

Masaaki Okubo; Tomomitsu Tahara; Tomoyuki Shibata; Masakatsu Nakamura; Yoshio Kamiya; Daisuke Yoshioka; Yoshiteru Maeda; Joh Yonemura; Takamitsu Ishizuka; Tomiyasu Arisawa; Ichiro Hirata

2011-01-01

121

Narrow-band Electrostatic Noise generated by an electron velocity space hole  

Microsoft Academic Search

Narrow-band Electrostatic Noise (NEN) is a common occurrence in the Earth's distant magnetotail. NEN is observed in a frequency range (100-316 Hz) that falls roughly between the electron and ion plasma frequencies. This mode may result from holes in the electron distribution function associated with slow shocks. An instability that is associated with this mode is studied using numerical simulations.

Robert L. Richard; Maha Ashour-Abdalla; Ferdinand V. Coroniti

1993-01-01

122

Statistical thermodynamics of strongly correlated electrons in a narrow band: Fermi liquid versus spin liquid  

Microsoft Academic Search

We propose a novel statistical-mechanical approach to a system of strongly correlated electrons in a partially filled narrow band which reproduces rigorously the situation in the atomic limit. In this approach the doubly occupied configurations are excluded both in the real and in the reciprocal spaces. Employing this principle we calculate the thermodynamic properties of those electrons. The metallic state,

J. Spalek; W. Wójcik

1988-01-01

123

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

124

Deep narrow band imagery of the diffuse ISM in M33  

NASA Technical Reports Server (NTRS)

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

Hester, J. Jeff; Kulkarni, Shrinivas R.

1990-01-01

125

Cyclotron side band emissions from magnetospheric electrons  

NASA Technical Reports Server (NTRS)

Very low frequency emissions with subharmonic cyclotron frequency from magnetospheric electrons were detected by the S(3)-A satellite (Explorer 45) whose orbit is close to the magnetic equatorial plane where the wave-particle interaction is most efficient. These emissions were observed during the main phase of a geomagnetic storm in the nightside of the magnetosphere outside of the plasmasphere. During the event of these side-band emissions, the pitch angle distributions of high energy electrons (greater than 50 keV) and of energetic protons (greater than 100 keV) showed remarkable changes with time, whereas those of low energy electrons and protons remained approximately isotropic. In this type of event, emissions consist essentially of two bands, the one below the equatorial electron gyrofrequency, and the other above. The emissions below are whistler mode, and the emissions above are electrostatic mode.

Maeda, K.

1975-01-01

126

Nanoscale needle shaped histidine and narrow vibrational Raman bands using visible excitation  

NASA Astrophysics Data System (ADS)

We observe intense and narrow vibrational Raman bands of nanoscale needles shaped histidine. The nano-needles have been grown from droplets of aqueous histidine (30 mM) on silica. Scanning electron microscopy reveals a combined structure of folded flat leaves and needles with diameters in the 50 nm range. The observed spectral bands are compared with density functional calculations. The C-H stretching vibrational bands of the imidazole ring are identified. C-H stretching mode of the back bone is found to be strongly conformational dependent.

Sonois, Vanessa; Faller, Peter; Bacsa, Wolfgang; Fazouan, Nejma; Estève, Alain

2007-05-01

127

An Interpretation of Banded Magnetospheric Radio Emissions  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

128

An interpretation of banded magnetospheric radio emissions  

NASA Astrophysics Data System (ADS)

Recently published Active Magnetospheric Particle Tracer Explorers/Ion Release Module (AMPTE/IRM) banded magnetospheric emissions, commonly referred to as ``(n+1/2)fce'' emissions, where fce is the electron gyrofrequency, are analyzed by treating them as analogous to sounder-stimulated ionospheric emissions. We show that both individual spectra of magnetospheric banded emissions and a statistically derived spectra observed over the 2-year lifetime of the mission can be interpreted in a self-consistent manner. The analysis, which predicts all spectral peaks within 4% of the observed peaks, interprets the higher-frequency emissions as due to low group velocity Bernstein-mode waves and interprets the lower-frequency emissions as eigenmodes of cylindrical-electromagnetic plasma oscillations. The demarcation between these two classes of emissions is the electron plasma frequency fpe where an emission is often observed. This fpe emission is not necessarily the strongest. None of the observed banded emissions were attributed to the upper hybrid frequency. We present Alouette 2 and ISIS 1 plasma resonance data and model electron temperature (Te) values to support the argument that the frequency spectrum of ionospheric sounder-stimulated emissions is not strongly temperature dependent and thus that the interpretation of these emissions in the ionosphere is relevant to other plasmas (such as the magnetosphere) where Ne and Te can be quite different but where the ratio fpe/fce is identical. The Ne values deduced from the spectral interpretation do not agree with the values determined from the AMPTE/IRM three-dimensional plasma instrument. The latter, which represent a lower bound, are found to be higher than the former by a factor of 3.2-3.5. All values were less than 1 cm-3, a domain known for measurement difficulties. One possible explanation is that the wave and plasma techniques respond to different components of a non-Maxwellian magneto-spheric electron distribution.

Benson, R. F.; Osherovich, V. A.; Fainberg, J.; Vinas, A.-F.; Ruppert, D. R.

2001-07-01

129

The design of LQG and H? controllers for use in active vibration control and narrow band disturbance rejection  

Microsoft Academic Search

This paper develops an H? design method for narrow band disturbance rejection. The method is based on the LQG approach via disturbance modelling given in De Nicolao (1992). These LQG and H? approaches to the narrow band disturbance rejection problem are then applied to a helicopter active vibration control problem

Allan J. Connolly; Michael Green; Joe F. Chicharo; Robert R. Bitmead

1995-01-01

130

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

131

Narrow Band Ratio Vegetation Indices and Itsrelationships With Rice Agronomic Variables  

NASA Astrophysics Data System (ADS)

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

Wang, Fumin; Huang, Jingfeng

132

[Narrow band multi-region level set method for remote sensing image].  

PubMed

Massive redundant contours happen when the classical Chan-Vese (C-V) model is used to segment remote sensing images, which have interlaced edges. What's more, this model can't segment homogeneous objects with multiple regions. In order to overcome this limitation of C-V model, narrow band multiple level set method is proposed. The use of N-1 curves is required for the segmentation of N regions and each curve represents one region. First, the level set model to establish an independent multi-region region can eliminate the redundant contours and avoids the problems of vacuum and overlap. Then, narrow band approach to level set method can reduce the computational cost. Experimental results of remote image verify that our model is efficient and accurate. PMID:22242504

Fang, Jiang-Xiong; Tu, En-Mei; Yang, Jie; Jia, Zhen-Hong; Nikola, Kasabov

2011-11-01

133

Monte Carlo modeling of light-tissue interactions in narrow band imaging  

NASA Astrophysics Data System (ADS)

Light-tissue interactions that influence vascular contrast enhancement in narrow band imaging (NBI) have not been the subject of extensive theoretical study. In order to elucidate relevant mechanisms in a systematic and quantitative manner we have developed and validated a Monte Carlo model of NBI and used it to study the effect of device and tissue parameters, specifically, imaging wavelength (415 versus 540 nm) and vessel diameter and depth. Simulations provided quantitative predictions of contrast-including up to 125% improvement in small, superficial vessel contrast for 415 over 540 nm. Our findings indicated that absorption rather than scattering-the mechanism often cited in prior studies-was the dominant factor behind spectral variations in vessel depth-selectivity. Narrow-band images of a tissue-simulating phantom showed good agreement in terms of trends and quantitative values. Numerical modeling represents a powerful tool for elucidating the factors that affect the performance of spectral imaging approaches such as NBI.

Le, Du V. N.; Wang, Quanzeng; Ramella-Roman, Jessica C.; Pfefer, T. Joshua

2013-01-01

134

Protection of a narrow-band BPSK communication system with an adaptive array  

NASA Astrophysics Data System (ADS)

This paper describes the performance of an adaptive array when used with narrow-band BPSK communication signals. The results of Ganz and Compton (1986) are extended to the case where the array bandwidth is as small as possible, equal to the desired signal symbol rate. To realize such a bandwidth reduction, it is necessary to reshape the BPSK signaling waveform before transmission to prevent intersymbol interference. This is done by passing the BPSK signal through a pulse-shaping filter at the transmitter. The performance of the optimal detector for the narrow-band BPSK signal is determined when this detector operates behind an adaptive array that is subjected to CW interference. The bit error probability is obtained as a function of the desired signal and interference powers and arrival angles as well as the array bandwidth.

Ganz, Matthew W.; Compton, R. T., Jr.

1987-10-01

135

Experimental Generation of Narrow-Band Paired Photons: from Damped Rabi Oscillation to Group Delay  

NASA Astrophysics Data System (ADS)

We report the experimental generation of narrow-band paired photons through electromagnetically induced transparency and spontaneous four-wave mixing in a two-dimensional magneto-optical trap (2D MOT). By controlling the optical depth of the 2D MOT from 0 to 40, the temporal length of the generated narrow-band paired photons can be varied from 50 to 900 ns. The ‘transition’ between damped Rabi oscillation and group delay is observed undisputedly. In the damped Rabi oscillation regime, a violation factor of the Cauchy—Schwartz inequality as large as 6642 is observed. In the group delay regime, sub-MHz linewidth (~ 0.65 MHz) paired photons are obtained with a generation rate of about 0.8 × 105 s?1.

Liao, Kai-Yu; Yan, Hui; He, Jun-Yu; Huang, Wei; Zhang, Zhi-Ming; Zhu, Shi-Liang

2014-03-01

136

Topologically nontrivial narrow bands in ultrathin SnTe films with defect superstructures  

NASA Astrophysics Data System (ADS)

It is shown that a two-dimensional topological insulator can be realized and the band topology (equivalently, the edge states) may be further controlled by charge doping in an ultrathin SnTe film with a defect superstructure. Based on first-principles density functional theory (DFT), we predict that a Sn-Te bilayer, if exfoliated from three-dimensional bulk SnTe in the (1?1?1) direction, has a trivial band topology in its pristine form, but is made topologically nontrivial by introducing an appropriate array of defects. The emergence of the topological state is ascribed to the formation of topologically nontrivial narrow bands near the Fermi level by spin–orbit splitting of defect-induced bands. In addition, we demonstrate that a transition between a topological insulator and a normal insulator is possible under the electron or hole doping which can be useful for controlling the topological edge states.

Kim, Minsung; Ihm, Jisoon

2014-06-01

137

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

138

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

139

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

140

Very narrow band model calculations of atmospheric fluxes and cooling rates  

Microsoft Academic Search

A new very narrow band model (VNBM) approach has been developed and incorporated into the MODTRAN atmospheric transmittance-radiance code. The VNBM includes a computational spectral resolution of 1 cm⁻¹, a single-line Voigt equivalent width formalism that is based on the Rodgers-Williams approximation and accounts for the finite spectral width of the interval, explicit consideration of line tails, a statistical line

L. S. Bernstein; A. Berk; P. K. Acharya; D. C. Robertson

1996-01-01

141

Very Narrow Band Model Calculations of Atmospheric Fluxes and Cooling Rates  

Microsoft Academic Search

A new very narrow band model (VNBM) approach has been developed and incorporated into the MODTRAN atmospheric transmittance-radiance code. The VNBM includes a computational spectral resolution of 1 cm1, a single-line Voigt equivalent width formalism that is based on the Rodgers-Williams approximation and accounts for the finite spectral width of the interval, explicit consideration of line tails, a statistical line

L. S. Bernstein; A. Berk; P. K. Acharya; D. C. Robertson; G. P. Anderson; J. H. Chetwynd; L. M. Kimball

1996-01-01

142

The value of narrow band imaging for early detection of laryngeal cancer  

Microsoft Academic Search

We evaluate the value of laryngoscopy using narrow band imaging (NBI) system in the diagnosis of precancerous and cancerous\\u000a laryngeal lesions. Thirty-four patients were suspected of having a total of 35 precancerous or cancerous laryngeal lesions\\u000a among patients receiving conventional white-light laryngoscopy. All 34 patients underwent laryngoscopy with NBI system to\\u000a determine whether those lesions were malignant before biopsy procedure.

Akihito Watanabe; Masanobu Taniguchi; Hitoshi Tsujie; Masao Hosokawa; Masahiro Fujita; Shigeyuki Sasaki

2009-01-01

143

Narrow-band frequency analysis for laser-based glass thickness measurement  

Microsoft Academic Search

This paper presents a narrow-band frequency analysis approach for a new laser interferometric heterodyne system, which is used for noncontact glass bottle wall thickness measurement. The measurement signal consists of a number of spectral components, the strongest of which is a reliable representation of the above-mentioned thickness. A fast method for searching and locating this frequency is vital for real-time

Bing He; François Cabestaing; Jack-Gérard Postaire; Ruodan Zhang

2005-01-01

144

Double symbol error rates for differential detection of narrow-band FM  

NASA Technical Reports Server (NTRS)

This paper evaluates the double symbol error rate (average probability of two consecutive symbol errors) in differentially detected narrow-band FM. Numerical results are presented for the special case of MSK with a Gaussian IF receive filter. It is shown that, not unlike similar results previously obtained for the single error probability of such systems, large inaccuracies in predicted performance can occur when intersymbol interference is ignored.

Simon, M. K.

1985-01-01

145

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

146

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

147

Band gap narrowing in BaTiO3 nanoparticles facilitated by multiple mechanisms  

NASA Astrophysics Data System (ADS)

In the present work, BaTiO3 nanoparticles of four different size ranges were prepared by sol-gel method. The optical band gap of these particles at some size ranges has come down to 2.53 eV from 3.2 eV, resulting in substantial increase in optical absorption by these ferroelectric nanoparticles making them potential candidates for light energy harvesting. XRD results show the presence of higher compressive strain in 23 nm and 54 nm size particles, they exhibit a higher band gap narrowing, whereas tensile strain is observed in 31 nm and 34 nm particles, and they do not show the marginal band gap narrowing. The 23 nm and 54 nm particles also show a coupling of free carriers to phonons by increasing the intensity of LO phonon mode at 715 cm-1. The higher surface charge density is expected in case of enhanced surface optical Raman modes (638 cm-1) contained in 31 and 34 nm size particles. In addition to this, the red shift in an LO mode Raman spectral line at 305 cm-1 with decrease in particle size depicts the presence of phonon confinement in it. The enhanced optical absorption in 23 nm and 54 nm size particles with a narrowed band gap of 3 eV and 2.53 eV is due to exchange correlation interactions between the carriers present in these particles. In 31 nm and 34 nm range particles, the absorption got bleached exhibiting increased band gaps of 3.08 eV and 3.2 eV, respectively. It is due to filling up of conduction band resulting from weakening of exchange correlation interactions between the charge carriers. Hence, it is concluded that the band gap narrowing in the nanoparticles of average size 23 nm/54 nm is a consequence of multiple effects like strain, electron-phonon interaction, and exchange correlation interactions between the carriers which is subdued in some other size ranges like 31 nm/34 nm.

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

2014-05-01

148

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

149

UNIDENTIFIED INFRARED EMISSION BANDS: PAHs or MAONs?  

SciTech Connect

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

Sun Kwok; Yong Zhang, E-mail: sunkwok@hku.hk [Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong (Hong Kong)

2013-07-01

150

Red supergiants in the Small Magellanic Cloud: The effects of metallicity on narrow-band classification indices  

Microsoft Academic Search

Narrow-band classification photometry, on a six color system that measures near infrared bands of TiO and CN, has been obtained for a set of red supergiants in the Small Magellanic Cloud. To investigate the effects of metallicity on the band strength indices, comparisons are made to supergiants in the LMC and the Galaxy. Two new variable stars are reported.

Robert F. Wing; Kyle M. Walker; D. Jack MacConnell; Edgardo Costa

2004-01-01

151

The Differences in Brain Activity between Narrow Band Noise and Pure Tone Tinnitus  

PubMed Central

Background Tinnitus is an auditory sensation characterized by the perception of sound or noise in the absence of any external sound source. Based on neurobiological research, it is generally accepted that most forms of tinnitus are attributable to maladaptive plasticity due to damage to auditory system. Changes have been observed in auditory structures such as the inferior colliculus, the thalamus and the auditory cortex as well as in non-auditory brain areas. However, the observed changes show great variability, hence lacking a conclusive picture. One of the reasons might be the selection of inhomogeneous groups in data analysis. Methodology The aim of the present study was to delineate the differences between the neural networks involved in narrow band noise and pure tone tinnitus conducting LORETA based source analysis of resting state EEG. Conclusions Results demonstrated that narrow band noise tinnitus patients differ from pure tone tinnitus patients in the lateral frontopolar (BA 10), PCC and the parahippocampal area for delta, beta and gamma frequency bands, respectively. The parahippocampal-PCC current density differences might be load dependent, as noise-like tinnitus constitutes multiple frequencies in contrast to pure tone tinnitus. The lateral frontopolar differences might be related to pitch specific memory retrieval.

Vanneste, Sven; Plazier, Mark; van der Loo, Elsa; Van de Heyning, Paul; De Ridder, Dirk

2010-01-01

152

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

153

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

SciTech Connect

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

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

2012-07-11

154

Narrow Band Imaging for the Detection of Gastric Intestinal Metaplasia and Dysplasia During Surveillance Endoscopy  

Microsoft Academic Search

Background  Surveillance of premalignant gastric lesions relies mainly on random biopsy sampling. Narrow band imaging (NBI) may enhance\\u000a the accuracy of endoscopic surveillance of intestinal metaplasia (IM) and dysplasia. We aimed to compare the yield of NBI\\u000a to white light endoscopy (WLE) in the surveillance of patients with IM and dysplasia.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Patients with previously identified gastric IM or dysplasia underwent a

Lisette G. Capelle; Jelle Haringsma; Annemarie C. de Vries; Ewout W. Steyerberg; Katharina Biermann; Herman van Dekken; Ernst J. Kuipers

2010-01-01

155

Update on narrow band imaging in disorders of the upper gastrointestinal tract.  

PubMed

With the ever-increasing concern regarding morbidity and mortality associated with diseases of the gastrointestinal tract, the importance of an effective and efficient diagnostic tool cannot be overstated. The standard of care currently is an examination using conventional white light endoscopy. This approach may occasionally overlook areas exhibiting a premalignant change. Numerous image-enhanced modalities have been recently introduced. Narrow band imaging (NBI) appears to be the most prominent of these and perhaps the most commonly used. Thepresent review will focus on some of the newer studies on NBI and its utility in the diagnosis of malignant, pre-malignant and chronic inflammatory conditions of the upper gastrointestinal tract. PMID:24303964

Singh, Rajvinder; Lee, Shok Y; Vijay, Nimal; Sharma, Prateek; Uedo, Noriya

2014-03-01

156

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

157

Fast reconstruction of Raman spectra from narrow-band measurements based on Wiener estimation  

NASA Astrophysics Data System (ADS)

Raman spectroscopy has demonstrated great potential in the study of biological molecules in a variety of biomedical applications. But slow data acquisition due to weak Raman signals from these molecules has prevented its wide use especially in an imaging setup. We propose a novel method to reconstruct the entire Raman spectrum from a few narrow-band measurements based on Wiener estimation. This method has been tested on Raman spectra from individual cells and shown fast speed and excellent accuracy. This method represents a new direction to speed up Raman data acquisition in an imaging setup to investigate fast changing phenomena.

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

2012-12-01

158

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

NASA Astrophysics Data System (ADS)

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

Matsuoka, Leo; Hashimoto, Masashi; Yokoyama, Keiichi

2012-07-01

159

LASERS, ACTIVE MEDIA: Narrow-band tunable alexandrite laser with passive Q switching  

NASA Astrophysics Data System (ADS)

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 F3- colour centres. The laser generated a single pulse of ~ 180 ns duration and of 1.5 mJ energy, and with a spectrum 5 × 10-3 cm-1 wide. The laser emitted in the spectral range 720 — 780 nm.

Tyryshkin, I. S.; Ivanov, N. A.; Khulugurov, V. M.

1998-06-01

160

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

SciTech Connect

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

Soufiani, A. (Ecole Centrale Paris, Chatenay-Malabry (France). Lab. d'Energetique Moleculaire et Macroscopique); Djavdan, E. (Centre de Recherche Claude-Delorme, Jouy-en-Josas (France))

1994-05-01

161

New narrow electronic band in heavily doped III–V semiconductors due to electron-phonon coupling  

Microsoft Academic Search

Electron-phonon interaction in heavily doped III–V semiconductors can lead to a singularity in the density of the localized electronic states in the narrow energy region near the bottom of the conduction band.

E. Ya Sherman

1995-01-01

162

Ratiometric luminescence thermometry based on crystal-field alternation at the extremely narrow (5)D0 ? (7)F2 transition band of europium(iii).  

PubMed

A dinuclear europium(iii) complex with a structure of [BP-(Eu(III))2-(ODA)3] (BP = 2,2'-bipyridine-6,6'-dicarboxylic acid bis(N-hydroxy-succinimide) ester, ODA = diglycolic acid) shows a fully reversible emission spectral change at the extremely narrow (5)D0 ? (7)F2 transition band in response to temperature changes ranging from 283 K to 333 K. PMID:24686443

Yuasa, Junpei; Mukai, Ryusuke; Hasegawa, Yasuchika; Kawai, Tsuyoshi

2014-06-26

163

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

164

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

165

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

PubMed Central

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.

2009-01-01

166

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

167

High-Aperture Narrow-Band Moire Filter in Volume Bragg Grating  

NASA Astrophysics Data System (ADS)

We propose narrow-band filter in volume Bragg grating (VBG) with bandwidth less than ten picometers. Two recorded Bragg gratings with the same modulation amplitudes and slightly different resonant wavelengths form moire pattern with slowly varying envelope of modulation amplitude. Each semi-period of modulation is just apodized reflective VBG; however two of them together form narrow-band transmission Fabry-Perot cavity due to phase ?-shift as result of sign change of slowly varying envelope. We fabricated first moire VBG filter in photo-thermo-refractive glass with resonance wavelength near 1550 nm, aperture size 5 mm, bandwidth 50 pm and 95% maximum transmittance. We considered also case when carrier Bragg grating wave vector does not coincide with moire pattern wave vector which allows creating filters with tunable one-period envelope profile from sinusoidal function to cosinusoidal one. Doubled resonant cavity with cosinusoidal profile demonstrates flattop transmission peak. Analytical expression for tunable bandwidth was found. Robust solid-state moire VBG filters tolerant to high-power laser irradiation with tunable filtering characteristics are suggested as optical elements for laser design and spectroscopy applications.

Mokhov, Sergiy; Lumeau, Julien; Smirnov, Vadim; Zeldovich, Boris; Glebov, Leonid

2010-03-01

168

The Cosmic Infrared Background Experiment: Flight Characterization Of The Ciber Narrow Band Spectrometer.  

NASA Astrophysics Data System (ADS)

Subtraction of the Zodiacal light foreground is the dominant source of uncertainty in absolute photometric measurements of the extra-galactic background at near-infrared to optical wavelengths. The second flight of the Cosmic Infrared Background ExpeRiment (CIBER) occurred on July 10th, 2010. CIBER is a NASA sounding rocket experiment carrying four co-aligned instruments including two imaging telescopes with wide passbands centered at 1 and 1.6 microns, respectively, as well as a low resolution spectrometer and a narrow-band spectrometer. THE CIBER spectrometers are absolutely calibrated in collaboration with NIST. The narrow-band spectrometer filter is centered on the Ca II solar Fraunhofer line at 854.2 nm and is designed to measure the equivalent width of the solar line reflected by the interplanetary dust in order to obtain an absolute measurement of the Zodiacal contribution to the infrared sky at that wavelength. In conjunction with measured low resolution spectrum from 700 to 1900 nm, this will provide an accurate independent check of the DIRBE Zodiacal light models. Here we describe the NBS instrument, calibration and in-flight characterization.

Levenson, Louis R.; Battle, J.; Bock, J. J.; Cooray, A.; Hristov, V.; Keating, B.; Lee, D.; Mason, P.; Matsumoto, T.; Matsuura, S.; Nam, U. W.; Renbarger, T.; Sullivan, I.; Suzuki, K.; Wada, T.; Zemcov, M.

2011-01-01

169

Emission Line Galaxies in a Narrow Strip Toward Perseus.  

National Technical Information Service (NTIS)

Many studies have suggested that emission line galaxies (ELG's) have spatial distributions that differ from non-emission line galaxies. The ELG's tend to avoid rich clusters and may sometimes reside within voids. This paper describes work in progress on a...

N. E. Ellman

1993-01-01

170

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

171

Emission line galaxies in a narrow strip toward Perseus  

NASA Technical Reports Server (NTRS)

Many studies have suggested that emission line galaxies (ELG's) have spatial distributions that differ from non-emission line galaxies. The ELG's tend to avoid rich clusters and may sometimes reside within voids. This paper describes work in progress on a redshift survey aimed both at determining the angular extent of the structures detected in deep pencil beam survey and at studying the characteristics of galaxies with respect to the rest of the sample.

Ellman, Nancy E.

1993-01-01

172

Spontaneous emission near the edge of a photonic band gap  

NASA Astrophysics Data System (ADS)

The spectral and dynamical features of spontaneous emission from two and three-level atoms in which one transition frequency lay near the edge of a photonic band gap (PBG) were derived. These features included temporal oscillations, fractionalized steady-state atomic population on the excited state, spectral splitting and subnatural bandwidth. The effect of N-1 unexcited atoms were also taken into account. The direct consequences of photon localization as embodied in the photon-atom bound state were observed. One feasible experimental accomplishment of these effects may ensue from laser-cooled atoms in the void regions of a PBG medium. Another option is the application of an organic impurity molecule such as pentacene. Such molecules were known to show extremely narrow linewidths when placed in fitting solid hosts.

John, Sajeev; Quang, Tran

1994-08-01

173

Enhancing the Macroscopic Yield of Narrow-Band High-Order Harmonic Generation by Fano Resonances  

NASA Astrophysics Data System (ADS)

Resonances in the photoabsorption spectrum of the generating medium can modify the spectrum of high-order harmonics. In particular, window-type Fano resonances can reduce photoabsorption within a narrow spectral region and, consequently, lead to an enhanced emission of high-order harmonics in absorption-limited generation conditions. For high harmonic generation in argon it is shown that the 3s3p6np1P1 window resonances (n =4, 5, 6) give rise to enhanced photon yield. In particular, the 3s3p64p1P1 resonance at 26.6 eV allows a relative enhancement up to a factor of 30 in a 100 meV bandwidth compared to the characteristic photon emission of the neighboring harmonic order. This enhanced, spectrally isolated, and coherent photon emission line has a relative energy bandwidth of only ?E /E=3×10-3. Therefore, it might be very useful for applications such as precision spectroscopy or coherent diffractive imaging. The presented mechanism can be employed for tailoring and controlling the high harmonic emission of manifold target materials.

Rothhardt, Jan; Hädrich, Steffen; Demmler, Stefan; Krebs, Manuel; Fritzsche, Stephan; Limpert, Jens; Tünnermann, Andreas

2014-06-01

174

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

175

Narrow band imaging with magnification for the diagnosis of lesions in the upper gastrointestinal tract.  

PubMed

Endoscopy plays an important role in the diagnosis and management of gastrointestinal (GI) tract disorders. Chromoendoscopy has proven to be superior to white light endoscopy for early detection of various GI lesions. This has however been fraught with problems. The use of color stains, time taken to achieve an effect and the learning curve associated with the technique has been some of the pitfalls. Narrow band imaging (NBI) particularly in combination with magnifying endoscopy may allow the endoscopist to accomplish a fairly accurate diagnosis with good histological correlation similar to results achieved with chromoendoscopy. Such enhanced detection of pre-malignant and early neoplastic lesions in the gastrointestinal tract should allow better targeting of biopsies and could ultimately prove to be cost effective. Various studies have been done demonstrating the utility of this novel technology. This article will review the impact of NBI in the diagnosis of upper gastrointestinal tract disorders. PMID:24368933

Singh, Rajvinder; Hussain, Asif; Loong, Cheong Kuan

2013-12-16

176

Editorial: shining a new narrow band of light on old problems.  

PubMed

Improvements in narrow band imaging (NBI) may provide an improved view of colonic mucosa for detection of polyps and adenomas. In this issue, Leung et al. report findings to suggest that this next-generation NBI technology is superior to conventional high-definition white light endoscopy in polyp detection. These findings are based on brighter illumination, which has been a problem with older generations of NBI, which did not increase polyp detection but were useful for polyp characterization. Although these findings are very promising for this new role of second-generation NBI in polyp detection, the study must be viewed with consideration of the history of the older NBI system, the analysis of which through multiple positive and negative studies ultimately led to the conclusion that it was not beneficial for detection. PMID:24896757

Chan, Daniel K; Wang, Kenneth K

2014-06-01

177

Pityriasis rubra pilaris sensitive to narrow band-ultraviolet B light therapy.  

PubMed

Pityriasis rubra pilaris (PRP) is a rare skin condition which typically presents in adults as red-orange plaques with islands of sparing, perifollicular keratotic papules, waxy palmoplantar keratoderma, and erythema with fine, diffuse scale. Currently, there are no well-established treatment guidelines for this condition. This is party due to a lack of universally effective treatments for PRP, with some cases being resistant to multiple topical and systemic therapies. Systemic retinoids have been used with some success. Several phototherapy regimens have lead to variable results. The authors present a case of PRP, unresponsive to 6 month treatment of isotretinoin, that was subsequently treated with narrow-band ultraviolet B (NB-UVB) light therapy with complete resolution after four months of light treatment. The observed clinical benefit may encourage future phototesting and consideration of NB-UVB light therapy in recalcitrant PRP cases. PMID:19271375

Vergilis-Kalner, Irene J; Mann, David J; Wasserman, Justin; Petronic-Rosic, Vesna; Tsoukas, Maria M

2009-03-01

178

The luminosities of red supergiants from Wing's eight-color narrow-band infrared photometry  

NASA Astrophysics Data System (ADS)

Calibration relations have been obtained for the intrinsic color index 0 ( = 5040/Te, Te being the observed color temperature of a star) and absolute magnitudes M(104) (at = 1.04 , in Wing's narrow-band photometric system), MV and MK as functions of TiO and CN photometric indices for K5-M5 supergiant stars. The accuracy of the distance moduli obtained when using these calibrations is about 0m·2. The distance moduli have been calculated for red supergiants which are members of open clusters. The distance scale for red supergiants based upon the M(104) (TiO, CN) absolute magnitude calibration (the distance modulus of 11m·4 being assumed for the Per OB1 stellar association) agrees with the distance scale for young open clusters based upon uvby?-photometry and Crawford's (1978) ZAMS for B-type stars.

Dambis, A. K.

179

Narrow-band Electrostatic Noise generated by an electron velocity space hole  

NASA Technical Reports Server (NTRS)

Narrow-band Electrostatic Noise (NEN) is a common occurrence in the Earth's distant magnetotail. NEN is observed in a frequency range (100-316 Hz) that falls roughly between the electron and ion plasma frequencies. This mode may result from holes in the electron distribution function associated with slow shocks. An instability that is associated with this mode is studied using numerical simulations. The growth of the instability depends on the size and shape of the hole. The hole mode can also be driven unstable by either an anisotropy in the electron distribution function or an ion beam. In all these cases the instability saturates at a low level and only a fraction of the available free energy is released.

Richard, Robert L.; Ashour-Abdalla, Maha; Coroniti, Ferdinand V.

1993-01-01

180

Band gap narrowing in zinc oxide-based semiconductor thin films  

NASA Astrophysics Data System (ADS)

A simple expression is proposed for the band gap narrowing (or shrinkage) in semiconductors using optical absorption measurements of spin coated 1 at. % Ga-doped ZnO (with additional 0-1.5 at. % zinc species) thin films as ?EBGN = Bn1/3 [1 - (nc/n)1/3], where B is the fitting parameter, n is carrier concentration, and nc is the critical density required for shrinkage onset. Its uniqueness lies in not only describing variation of ?EBGN correctly but also allowing deduction of nc automatically for several M-doped ZnO (M: Ga, Al, In, B, Mo) systems. The physical significance of the term [1 - (nc/n)1/3] is discussed in terms of carrier separation.

Kumar, Jitendra; Kumar Srivastava, Amit

2014-04-01

181

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

NASA Astrophysics Data System (ADS)

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

Rui, Rui; Bao, Chang-chun

2013-03-01

182

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

NASA Technical Reports Server (NTRS)

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

Gridley, D.

1982-01-01

183

Optimization of Rowland circle mounts for grating demultiplexers and narrow-band spectrographs.  

PubMed

A simple equation for the parameters of the Rowland circle grating mount is derived that ensures that the astigmatism and the meridional spherical aberration are stationary at the wavelength of correction. This is important in optimizing the design of grating multiplexers-demultiplexers and cross connects in wavelengthdivision multiplexed networks and high-resolution narrow-band spectrographs. An analysis of aberrations in three-dimensional and planar two-dimensional optical schemes is presented, and it is shown that in the wavelength range of 1530-1570 nm diffraction-limited performance can be achieved for 160 channels in a three-dimensional multiplexer-demultiplexer and for more than 800 channels for a planar free-space scheme. PMID:19876260

Churin, E G; Bayvel, P; Stavdas, A; Midwinter, J E; Hill, A M

1996-07-15

184

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

NASA Astrophysics Data System (ADS)

We develop a theoretical model to study optical phase conjugation via stimulated Brillouin scattering (OPC-SBS) in narrow band gap transversely magnetized semiconductors. Threshold value of pump electric field and reflectivity of the image radiation for the onset of OPC-SBS are estimated. The analysis is applied to both cases viz. centrosymmetric (CS) and non-centrosymmetric (NCS) crystals. Numerical estimates made for n-type InSb crystal at liquid nitrogen temperature duly irradiated by nanosecond pulsed 10.6 ?m CO 2 laser shows that high OPC-SBS reflectivity (90%) can be achieved in NCS crystals at moderate pump electric fields if the crystal is used as an optical waveguide with relatively large interaction length ( L = 5 mm) which proves its potential in practical applications such as fabrication of phase conjugate mirrors.

Singh, M.; Aghamkar, P.

2008-03-01

185

Can narrow-band imaging be used to determine the surgical margin of superficial hypopharyngeal cancer?  

PubMed

Narrow-band imaging (NBI) is a novel optical technique that uses narrow bandwidth filters in a video endoscope system to improve the diagnostic capability of endoscopes in characterizing tissues. It is well known that early identification of neoplasia in the gastrointestinal tract using this technique might make it possible to reduce the suffering of patients caused by loss of function or severe complications after radical surgery. Several reports have introduced this system as a preoperative examination to evaluate the lateral spread of the neoplastic lesions in the oropharynx or hypopharynx. We experienced a case with hypopharyngeal cancer in which we were able to avoid underestimating cancer lesions following insufficient resection using the NBI system. A 62-year-old female underwent partial hypopharyngectomy with the margin estimated by an NBI view coupled with reconstruction of the hypopharynx while preserving the larynx. The resected specimen was cut into serial sections for a detailed pathology examination. The surgical margin seemed to be wide enough and it could be assumed that if possible we should observe these cancers with conventional electroendoscopy and NBI before treatment. PMID:18596837

Orita, Yorihisa; Kawabata, Kazuyoshi; Mitani, Hiroki; Fukushima, Hirofumi; Tanaka, Shiro; Yoshimoto, Seiichi; Yamamoto, Noriko

2008-06-01

186

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

NASA Astrophysics Data System (ADS)

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 ˜g2?-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.

Kartashova, Elena

2012-10-01

187

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

NASA Technical Reports Server (NTRS)

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

Cess, Robert D.; Potter, Gerald L.

1986-01-01

188

Atomic and electronic structures of novel ternary and quaternary narrow band-gap semiconductors  

NASA Astrophysics Data System (ADS)

This thesis concerns mainly with atomic and electronic structures of novel ternary and quaternary chalcogenide narrow band-gap semiconductors which are of great interest for infrared devices, photovoltaics, and high temperature thermoelectrics. More specifically, it presents studies of charge ordering and self-assembled nanostructures in a class of quaternary systems and their phase diagram, defect clustering and nanostructure formation in bulk thermoelectrics, atomic and electronic structures of ternary chalcogenides, and nature of defect states in narrow band-gap semiconductors. Studies are carried out using Monte Carlo (MC) and ab initio methods to understand the nanostructuring phenomenon observed in AgPbmSbTem+2 and similar systems. MC simulations in these quaternaries using an ionic model show a distinct phase diagram and a variety of structural orderings depending on the concentration of the monovalent and trivalent atoms as a result of the long-range nature of the Coulomb interaction. Ab initio density functional theory (DFT) based calculations also show that monovalent and trivalent impurities in PbTe, SnTe, and GeTe-based bulk thermoelectric materials like to come close to each other and form clusters or some sort of embedded nanostructures. Interplay of atomic and electronic structures and band gap formation in I-V-VI2 and TI-based III-V-VII2 tertiary chalcogenides (I=Ag, Cu, Au, Na, K; V=As, Sb, Bi; VII=S, Se, Te) are studied using ab initio electronic structure calculations. These calculations have been able to identify low energy ordered structures which are consistent with experiments. Several intriguing physical properties of these materials can be understood in terms of the calculated electronic structure. This thesis suggests how to modify a certain ternary by replacing its constituting elements) such that the electronic structure shows desired features for different applications. Comprehensive studies of the nature of defect-induced electronic states associated with a large class of substitutional impurities and native point defects in PbTe, SnTe, and GeTe are carried out using DFT and supercell models. Calculations are also carried out in PbTe thin films and nanoclusters to study how the defect states change in going from one geometry to another. This thesis also concerns with energetics of the defects, particularly defect formation energy, which may be able to give some information on the doping mechanism and the distribution of the defects in these systems. Based on the calculated electronic structures, one can explain the peculiar properties of PbTe doped with group III (Ga, In, T1) impurities and the observed transport properties of PbTe, SnTe, and GeTe-based thermoelectrics.

Hoang, Khang

189

Effects of narrow-band filters on the output enalytical extension of the Bedrosian-Rice formulation  

NASA Astrophysics Data System (ADS)

The problem of determining the wave-form distortion produced by a (symetrical) narrow-band linear filter when an off-tune, simultaneously amplitude- and angle-modulated carrier is introduced, is analytically solved by an extension of the Bedrosian-Rice approach. Here, both the instantaneous angle and envelope of the resulting narrow-band output are determined. The results provide a basis for numerical calculations and extension to the more complex problem of interference effects produced by multiple inputs of the above type.

Middleton, D.

1985-04-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

191

Band-gap narrowing in ?-(CrxFe1-x)2O3 solid-solution films  

NASA Astrophysics Data System (ADS)

We report on structural and optical properties for the (0001)-oriented ?-(CrxFe1-x)2O3 (0 <= x <= 1) epitaxial films prepared on c-sapphire substrates by using pulsed-laser deposition. Pure corundum phase with atomically flat surface was obtained in the entire composition range. Optical absorption spectra for the films with 0.2 < x < 0.9 showed a nearly constant band-gap (1.7 eV), which is narrower than those of ?-Fe2O3 (2.1 eV) and ?-Cr2O3 (3.0 eV). The result suggests that the band-gap narrowing arises from a type-II band alignment of these oxides and the fundamental band-gap lies between the Cr t2g and O 2p occupied states and the Fe t2g* empty state.

Mashiko, Hisanori; Oshima, Takayoshi; Ohtomo, Akira

2011-12-01

192

Multicolor Fluorescent Semiconducting Polymer Dots with Narrow Emissions and High Brightness  

PubMed Central

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 intra-particle energy transfer led to highly bright, narrow emissions. The emission full-width at half maximum (FWHM) of the resulting Pdots varies from 40 nm to 55 nm, which is 1.5~2 times narrower than those of conventional semiconducting polymer dots. BODIPY520 Pdots was about an order of magnitude brighter than commercial Qdot 525 under identical laser excitation conditions. Fluorescence imaging and flow cytometry experiments indicate the narrow emissions from these bright Pdots are promising for multiplexed biological detections.

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.

2013-01-01

193

Spectral variations in narrow band imaging depth-selectivity: mucosal scattering vs. hemoglobin absorption  

NASA Astrophysics Data System (ADS)

Spectral variations in contrast enhancement of mucosal vasculature are a key feature of narrow band imaging (NBI) devices. In prior NBI studies, the enhanced visualization of larger, deeper vessels with green light (e.g., 540 nm) relative to violet light (e.g., 415 nm) has often been attributed to the well-known monotonic decrease in scattering coefficient with wavelength in biological tissues. We have developed and implemented numerical and experimental approaches to elucidate and quantify this and other light-tissue interaction effects relevant to NBI. A Monte Carlo model incorporating vessel-like inclusions with a range of diameters (20 to 400 microns) and depths (20 to 400 microns) was used to predict reflectance and fluence distributions in the tissue and calculate vessel contrast values. These results were compared to experimental measurements based on a liquid phantom with a hemoglobin-filled capillary. By comparing results for cases representing mucosa regions with and without blood, we were able to evaluate the relative significance of absorption and scattering on spectral variations in depth-selectivity. Results indicate that at 415 nm, detection of superficial vasculature with NBI was almost entirely dependent on the absorption coefficient of the blood in the vessel of interest. The enhanced visualization of deep vessels at 540 nm bands relative to 415 nm was due primarily to absorption by the superficial vasculature rather than a decrease in scattering coefficient. While computationally intensive, our numerical modeling approach provides unique insights into the light propagation mechanisms underlying this emerging clinical imaging technology.

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

2013-03-01

194

Narrow-Band Photometry of Comet C/1995 O1 (Hale-Bopp)  

NASA Astrophysics Data System (ADS)

Photometric observations of comet C/1995 O1 (Hale-Bopp) carried out at the Stará Lesná Observatory since February to April 1997 are analyzed and discussed. Emission band fluxes and continuum fluxes are presented, from which the total numbers of molecules in the columns of the coma encircled by diaphragms are calculated. The production rates are estimated from the conventional Haser model. We found that the photometric exponent of dust contribution two months prior perihelion was n = 5.2. The photometric exponent n of the cometary magnitude solely to the C2 emission alone equals 3.3 and that of CN equals 2.5. These values can be explained by a fact that the maximums of production rates of the gases were reached between March 2and 12 and not at the perihelion as it is valid for dust. These results are compared with the values of 1P/Halley (1986 III) under the similar conditions, obtained with the same method and instrument. C/Hale-Bopp exhibited 4.1 times more molecules radiating the CN-emission than 1P/Halley in the same column of the coma. The continuum flux of C/Hale-Bopp was also very strong. The ratios (to 1P/Halley) are 94:1 (Cont. 484.5) and 74:1 (Cont. 365.0). The cometary colour was the same as that of the Sun.

Svore?, J.; Komžík, R.; Neslušan, L.; Živ?ovský, J.

1997-07-01

195

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

196

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

197

Narrow Band Imaging for the Detection of Gastric Intestinal Metaplasia and Dysplasia During Surveillance Endoscopy  

PubMed Central

Background Surveillance of premalignant gastric lesions relies mainly on random biopsy sampling. Narrow band imaging (NBI) may enhance the accuracy of endoscopic surveillance of intestinal metaplasia (IM) and dysplasia. We aimed to compare the yield of NBI to white light endoscopy (WLE) in the surveillance of patients with IM and dysplasia. Methods Patients with previously identified gastric IM or dysplasia underwent a surveillance endoscopy. Both WLE and NBI were performed in all patients during a single procedure. The sensitivity of WLE and NBI for the detection of premalignant lesions was calculated by correlating endoscopic findings to histological diagnosis. Results Forty-three patients (28 males and 15 females, mean age 59 years) were included. IM was diagnosed in 27 patients; 20 were detected by NBI and WLE, four solely by NBI and three by random biopsies only. Dysplasia was detected in seven patients by WLE and NBI and in two patients by random biopsies only. Sixty-eight endoscopically detected lesions contained IM: 47 were detected by WLE and NBI, 21 by NBI only. Nine endoscopically detected lesions demonstrated dysplasia: eight were detected by WLE and NBI, one was detected by NBI only. The sensitivity, specificity, positive and negative predictive values for detection of premalignant lesions were 71, 58, 65 and 65% for NBI and 51, 67, 62 and 55% for WLE, respectively. Conclusions NBI increases the diagnostic yield for detection of advanced premalignant gastric lesions compared to routine WLE.

Haringsma, Jelle; de Vries, Annemarie C.; Steyerberg, Ewout W.; Biermann, Katharina; van Dekken, Herman; Kuipers, Ernst J.

2010-01-01

198

Pharyngo-laryngeal examination with the narrow band imaging technology: early experience.  

PubMed

The prognosis of cancer patients is highly dependent on the time of diagnosis. Early, stage 1 disease is often curable whereas late stage diseases are usually beyond curable treatments. Therefore, new diagnostic tools for malignancies of the upper aerodigestive tract are developed all the time and narrow band imaging (NBI) is one of these new options for early diagnostics. In this paper, we describe the implementation of NBI technique in our institution. During the first 6 weeks we used NBI to examine 73 patients with different types of pharyngeal or laryngeal problems. Most of the patients (77%) were on follow-up visits after earlier malignant disease. In our series we had 11 NBI-positive patients and the histological diagnosis was carcinoma or dysplasia among 10 of these. Among the NBI negative patients we found four carcinomas. It is notable that NBI affected the decision of a biopsy procedure in three patients, with final diagnosis of dysplasia or carcinoma. In conclusion, we find NBI useful in the diagnostics of malignancies of the upper aerodigestive tract. This is a useful tool in improving the accuracy of the diagnostics. However, it still takes an experienced clinician and a learning curve can be expected. PMID:21327999

Irjala, Heikki; Matar, Nayla; Remacle, Marc; Georges, Lawson

2011-06-01

199

Narrow-band imaging without magnification for detecting early esophageal squamous cell carcinoma  

PubMed Central

AIM: To compare narrow-band imaging (NBI) without image magnification, and chromoendoscopy with Lugol’s solution for detecting high-grade dysplasia and intramucosal esophageal squamous cell carcinoma (SCC) in patients with head and neck cancer. METHODS: This was a prospective observational study of 129 patients with primary head and neck tumors consecutively referred to the Gastrointestinal Endoscopy Unit of Hospital das Clínicas, São Paulo University Medical School, Brazil, between August 2006 and February 2007. Conventional examinations with NBI and Lugol chromoendoscopy were consecutively performed, and the discovered 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. RESULTS: Of the 129 patients, nine (7%) were diagnosed with SCC, 5 of which were in situ and 4 which were intramucosal. All carcinomas were detected through NBI and Lugol chromoendoscopy. Only 4 lesions were diagnosed through conventional examination, all of which were larger than 10 mm. CONCLUSION: NBI technology with optical filters has high sensitivity and high negative predictive value for detecting superficial esophageal SCC, and produces results comparable to those obtained with 2.5% Lugol chromoendoscopy.

Ide, Edson; Maluf-Filho, Fauze; Chaves, Dalton Marques; Matuguma, Sergio Eiji; Sakai, Paulo

2011-01-01

200

Narrow Angle Diversity using ACTS Ka-band Signal with Two USAT Ground Stations  

NASA Technical Reports Server (NTRS)

Two ultra small aperture terminal (USAT) ground stations, separated by 1.2 km in a narrow angle diversity configuration, received a continuous Ka-band tone sent from Cleveland Link Evaluation Terminal (LET). The signal was transmitted to the USAT ground stations via NASA's Advanced Communications Technology Satellite (ACTS) steerable beam. Received signal power at the two sites was measured and analyzed. A dedicated datalogger at each site recorded time-of-tip data from tipping bucket rain gauges, providing rain amount and instantaneous rain rate. WSR-88D data was also obtained for the collection period. Eleven events with ground-to-satellite slant-path precipitation and resultant signal attenuation were observed during the data collection period. Fade magnitude and duration were compared at the two sites and diversity gain was calculated. These results exceeded standard diversity gain model predictions by several decibels. Rain statistics from tipping bucket data and from radar data were also compared to signal attenuation. The nature of Florida's subtropical rainfall, specifically its impact on signal attenuation at the sites, was addressed.

Kalu, A.; Emrich, C.; Ventre, J.; Wilson, W.; Acosta, R.

1998-01-01

201

Method for narrow-band search of continuous gravitational wave signals  

NASA Astrophysics Data System (ADS)

Targeted searches of continuous waves from spinning neutron stars normally assume that the frequency of the gravitational wave signal is at a given known ratio with respect to the rotational frequency of the source, e.g., twice for an asymmetric neutron star rotating around a principal axis of inertia. In fact this assumption may well be invalid if, for instance, the gravitational wave signal is due to a solid core rotating at a slightly different rate with respect to the star crust. In this paper we present a method for narrow-band searches of continuous gravitational wave signals from known pulsars in the data of interferometric detectors. This method assumes source position is known to high accuracy, while a small frequency and spin-down range around the electromagnetic-inferred values is explored. Barycentric and spin-down corrections are done with an efficient time-domain procedure. Sensitivity and computational efficiency estimates are given and results of tests done using simulated data are also discussed.

Astone, P.; Colla, A.; D'Antonio, S.; Frasca, S.; Palomba, C.; Serafinelli, R.

2014-03-01

202

Teleradiology support via narrow band ISDN and the JPEG still image compression standard  

NASA Astrophysics Data System (ADS)

The importance of remote access to both radiological images and medical information has stimulated many demonstration projects utilizing a variety of telecommunications providers'' offerings. Teleradiology over modest cost channels can achieve adequate response times using a combination of narrow-band ISDN and data compression. A demonstration project, developed in collaboration with Southwestern Bell Technology Resources, Inc., utilizes the aggregate bandwidth of two B channels (achieving a rate of 120 kb/s) and a compression/ decompression implementation based on the JPEG block-oriented DCT approach. System response measurements for an Inquiry and Display Station accessing the Mallinckrodt Institute of Radiology''s (MIR) Radiology Image and Information Management (RIM) Testbed via the N-ISDN connection shows response times to be within 20 seconds. Viewing applications have been demonstrated at sites within St. Louis and at RSNA-90 in Chicago. Image quality metrics and observations are presented for a sample digitized film chest radiograph and computed radiographs of portable x-ray examinations vis a demonstration at the poster session.

Blaine, G. James; Moore, Stephen M.; Cox, Jerome R., Jr.; Lewis, Robert C.; Senol, Evren; Whitman, Robert A.

1992-07-01

203

Narrow-band full Stokes polarimetry of small structures on the Sun with speckle methods  

NASA Astrophysics Data System (ADS)

Aims:For the detection and the study of small-scale magnetic fields on the Sun, it is important to obtain observations with both high spatial resolution and high polarimetric sensitivity. Methods: A second narrow-band etalon and a full Stokes polarimeter, based on ferroelectric liquid crystals, were implemented in the two-dimensional “Göttingen” Fabry-Perot spectrometer/polarimeter at the Vacuum Tower Telescope, Observatorio del Teide/Tenerife. First observations with the Fe I 6173 Å line and their data analysis with speckle methods are described. Results: The new polarimeter yields magnetograms of a field of view of 31 arcsec×52 arcsec with minimised seeing induced signals and without spurious signals as from the use of beam-splitting calcites. The achieved spatial and temporal resolution are 0.30-0.35 arcsec and 36 s, respectively. With a detection limit for the field strength of 16 G (\\cor3?), a polarimetric sensitivity of 7-8×1015 Mx is obtained. Examples of intensity maps, Dopplergrams, and magnetograms from quiet and active regions on the Sun are discussed. Some of the results on solar magnetism are on 1) a pore with small-scale structure where we find a region with very low temperature gradient, 2) polar faculae with strong magnetic field signals and weaker signals in other areas surrounding them, and 3) small-scale inter-network magnetic fields with area fillings in the resolution elements of the order of 0.15.

Bello González, N.; Kneer, F.

2008-03-01

204

Low energy narrow band non-coherent infrared illumination of human semen and isolated sperm.  

PubMed

Sixty-two samples of human normal and abnormal semen and 23 samples of washed sperm were illuminated for 4 minutes with a narrow band non-coherent infrared device (BioBeam). Immediately after illumination the following parameters were examined in comparison with appropriate controls: motility, viability and morphology, fructose content of semen, acrosome reaction of sperm, viscosity of seminal plasma and analysis of the protein pattern. The mean value of motility grade calculated for the total number of 62 semen samples was 2.58 +/- 0.79 versus 2.17 +/- 0.75 (non illuminated controls), P less than 0.005. The mean value of motility grade of 23 samples of washed sperm was 2.89 +/- 0.77 versus 2.43 +/- 0.62, respectively (P less than 0.01). In two illuminated seminal plasma specimens, the viscosity was decreased by 8.8% and 14.8%, the protein content and pattern remained, however, unchanged. Neither the percentages of motile, viable and morphologically normal sperm, nor the fructose content of semen were found to be affected by the illumination. PMID:1952126

Singer, R; Sagiv, M; Barnet, M; Levinsky, H; Segenreich, E; Fuchs, Y; Mendes, E; Yehoshua, H

1991-01-01

205

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

PubMed Central

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

Forchheimer, Daniel; Tholen, Erik A; Haviland, David B

2013-01-01

206

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

PubMed Central

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

Reich, Adam; Medrek, Karolina

2013-01-01

207

Altitude and latitude distribution of atmospheric aerosol and water vapor from the narrow-band lunar eclipse photometry  

Microsoft Academic Search

This work contains the description of two narrow IR-bands observational data of the total lunar eclipse of March 3, 2007, one- and two-dimensioned procedures of radiative transfer equation solution. The results of the procedure are the extinction values for atmospheric aerosol and water vapor at different altitudes in the troposphere along the Earth's terminator crossing North America, Arctic, Siberia and

Oleg S. Ugolnikov; Igor A. Maslov

2008-01-01

208

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

209

Numerical simulation of evaluation of surface breaking cracks by array-lasers generated narrow-band SAW  

NASA Astrophysics Data System (ADS)

Most of the factors limiting the extensive application of laser-based ultrasonic for nondestructive evaluation of surface breaking crack are its poor sensitivity, low efficiency relative to conventional contact ultrasonic methods and limit on the dimension of the cracks. For this reason, a new technique that multiplepulse narrow-band ultrasound generated by laser arrays has been proposed. It is found that crack detection dependent on spectrum of narrow-band ultrasound generated by laser arrays can be operated with low amplitude requirements. In this paper, the narrow-band ultrasound generated by pulse laser arrays interacting with surface breaking cracks has been simulated in detail by the finite element method (FEM) according to the thermoelastic theory. The pulsed array lasers were assumed to be transient heat source, and the surface acoustic wave (SAW) which propagating on the top of the plate was computed based on thermoelastic theory. Then the frequency spectrums of both reflected waves by crack and transmission ones through crack were compared with the direct waves. Results demonstrate that multiple-frequency components of the narrow-band ultrasound were varied with change of the depth of surface breaking cracks significantly, which provides the possibility for precise evaluation of surface breaking cracks.

Dong, Li-Ming; Ni, Chen-Yin; Shen, Zhong-Hua; Ni, Xiao-Wu

2011-09-01

210

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

PubMed Central

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

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

2008-01-01

211

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

NASA Astrophysics Data System (ADS)

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

Mollenhauer, Hannes; Cuntz, Thomas; Bumberger, Jan

2014-05-01

212

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

213

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

214

Usefulness of magnifying endoscopy with narrow-band imaging for diagnosis of depressed gastric lesions  

PubMed Central

The usefulness of magnifying endoscopy with narrow-band imaging (ME-NBI) for the diagnosis of early gastric cancer is well known, however, there are no evaluation criteria. The aim of this study was to devise and evaluate a novel diagnostic algorithm for ME-NBI in depressed early gastric cancer. Between August, 2007 and May, 2011, 90 patients with a total of 110 depressed gastric lesions were enrolled in the study. A diagnostic algorithm was devised based on ME-NBI microvascular findings: microvascular irregularity and abnormal microvascular patterns (fine network, corkscrew and unclassified patterns). The diagnostic efficiency of the algorithm for gastric cancer and histological grade was assessed by measuring its mean sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy. Furthermore, inter- and intra-observer variation were measured. In the differential diagnosis of gastric cancer from non-cancerous lesions, the mean sensitivity, specificity, PPV, NPV, and accuracy of the diagnostic algorithm were 86.7, 48.0, 94.4, 26.7, and 83.2%, respectively. Furthermore, in the differential diagnosis of undifferentiated adenocarcinoma from differentiated adenocarcinoma, the mean sensitivity, specificity, PPV, NPV, and accuracy of the diagnostic algorithm were 61.6, 86.3, 69.0, 84.8, and 79.1%, respectively. For the ME-NBI final diagnosis using this algorithm, the mean ? values for inter- and intra-observer agreement were 0.50 and 0.77, respectively. In conclusion, the diagnostic algorithm based on ME-NBI microvascular findings was convenient and had high diagnostic accuracy, reliability and reproducibility in the differential diagnosis of depressed gastric lesions.

SUMIE, HIROAKI; SUMIE, SHUJI; NAKAHARA, KEITA; WATANABE, YASUTOMO; MATSUO, KEN; MUKASA, MICHITA; SAKAI, TAKESHI; YOSHIDA, HIKARU; TSURUTA, OSAMU; SATA, MICHIO

2014-01-01

215

Endoscopic diagnosis of cervical esophageal heterotopic gastric mucosa with conventional and narrow-band images  

PubMed Central

AIM: To compare the diagnostic yield of heterotopic gastric mucosa (HGM) in the cervical esophagus with conventional imaging (CI) and narrow-band imaging (NBI). METHODS: A prospective study with a total of 760 patients receiving a CI examination (mean age 51.6 years; 47.8% male) and 760 patients undergoing NBI examination (mean age 51.2 years; 45.9% male). The size of HGM was classified as small (1-5 mm), medium (6-10 mm), or large (> 1 cm). A standardized questionnaire was used to obtain demographic characteristics, social habits, and symptoms likely to be related to cervical esophageal HGM, including throat symptoms (globus sensation, hoarseness, sore throat, and cough) and upper esophageal symptoms (dysphagia and odynophagia) at least 3 mo in duration. The clinicopathological classification of cervical esophageal HGM was performed using the proposal by von Rahden et al. RESULTS: Cervical esophageal HGM was found in 36 of 760 (4.7%) and 63 of 760 (8.3%) patients in the CI and NBI groups, respectively (P = 0.007). The NBI mode discovered significantly more small-sized HGM than CI (55% vs 17%; P < 0.0001). For the 99 patients with cervical esophageal HGM, biopsies were performed in 56 patients; 37 (66%) had fundic-type gastric mucosa, and 19 had antral-type mucosa. For the clinicopathological classification, 77 patients (78%) were classified as HGM?I?(asymptomatic carriers); 21 as HGM II (symptomatic without morphologic changes); and one as HGM III (symptomatic with morphologic change). No intraepithelial neoplasia or adenocarcinoma was found. CONCLUSION: NBI endoscopy detects more cervical esophageal HGM than CI does. Fundic-type gastric mucosa constitutes the most common histology. One-fifth of patients have throat or dysphagic symptoms.

Cheng, Chi-Liang; Lin, Cheng-Hui; Liu, Nai-Jen; Tang, Jui-Hsiang; Kuo, Yen-Lin; Tsui, Yi-Ning

2014-01-01

216

Meta-Analysis: Narrow Band Imaging for Diagnosis of Gastric Intestinal Metaplasia  

PubMed Central

Background Distinguishing early gastric cancer is challenging with current imaging techniques. Narrow band imaging (NBI) is effective for characterizing gastric lesions. Objectives The aim of this meta-analysis was to estimate the diagnostic accuracy of NBI in the gastric intestinal metaplasia (GIM). Methods We performed data analysis using Meta-DiSc (version 1.4) and STATA (version 11.0) software. To assess study quality and potential for bias, we used the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Results Six studies involving 347 patients were included. On a per-patient basis, the sensitivity of NBI for diagnosis of GIM was 0.65 (95% CI ?=? 0.56–0.74), and the specificity was 0.93 (95% CI ?=? 0.88–0.97). The area under the summary receiver operating characteristic (SROC) curve was 0.8731. However, on a per-lesion basis, the sensitivity and specificity of NBI were 0.69 (95% CI ?=? 0.63–0.74) and 0.91 (95% CI ?=? 0.87–0.94), respectively. The SROC was 0.9009. The pooled sensitivity and specificity of magnification endoscopy (NBI-ME) were 0.76 (95% CI ?=? 0.61–0.87) and 0.89 (95% CI ?=? 0.80–0.94), respectively, on per-patient analysis. On a per-lesion basis, the pooled sensitivity and specificity of NBI-ME were 0.84 (95% CI ?=? 0.76–0.89) and 0.93 (95% CI ?=? 0.89–0.96), respectively. Heterogeneity was observed with an I2 for diagnostic odds ratio (DOR) of 0.01% and 85.8%, respectively. There was no statistical significance for the evaluation of publication bias. Conclusions Our meta-analysis shows that NBI is a useful tool for differential diagnosis of GIM with relatively low sensitivity and high specificity.

Song, Jia; Zhang, Jixiang; Wang, Jun; Guo, Xufeng; Wang, Jing; Liu, Ya; Dong, Weiguo

2014-01-01

217

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

PubMed

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

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

2013-08-01

218

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

219

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

220

Argon-induced pressure broadening, shifting, and narrowing in the CN A2?-X2?+ (1-0) band.  

PubMed

Selected isolated rotational transitions in the 1-0 band of the red A(2)?-X (2)?(+) system in CN have been recorded with transient frequency modulation spectroscopy as a function of argon pressure up to 0.2 atm at room temperature. Line shapes were fit using Fourier transforms of a parametrized time correlation function, including Doppler and velocity-dependent collisional broadening, and collisional shifts. Deviations from Voigt line shapes can be equally well fit by modeling the narrowing with a speed-dependent collision model or with a velocity-changing collisional narrowing model. Pressure broadening coefficients were observed with little rotational state dependence, in the range of 0.070-0.075 cm(-1) atm(-1). In contrast, stronger and qualitatively different rotational state dependences are observed for both pressure-dependent blue shift coefficients and the narrowing parameters. No asymmetry in the pressure broadened lines was observed. PMID:23725543

Forthomme, Damien; McRaven, Christopher P; Sears, Trevor J; Hall, Gregory E

2013-11-21

221

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

222

Spontaneous emission near the edge of a photonic band gap  

NASA Astrophysics Data System (ADS)

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 presence of N-1 unexcited atoms we show that the collective time scale factor is equal to N?, where ?=2/3 for an isotropic band gap and ?=1 or 2 for anisotropic two-dimensional or three-dimensional band edges, respectively.

John, Sajeev; Quang, Tran

1994-08-01

223

Predictions of narrow-band acoustic time reversal in the shallow ocean  

NASA Astrophysics Data System (ADS)

A time-reversing array (TRA) can retrofocus acoustic energy, in both time and space, to the original sound- source location without any environmental information. This unique capability may be degraded in time-dependent, lossy, or noisy acoustic environments. A broad computational and analytical investigation into narrow- band acoustic time reversal in the shallow ocean has been undertaken. This includes investigating (1)variability in the water column due to dynamic linear internal waves, (2)roughness in the ocean bottom, and (3)limiting orientations of TRAs. TRA retrofocusing performance predictions are primarily determined via monochromatic propagation simulations using the wide-angle parabolic equation code RAM (Collins 1993, 1994, and 1998). Results for the influence of source-array range, source depth, channel depth, acoustic frequency, bottom absorption, bottom roughness, internal wave strength, roundtrip time delay, and array orientation and spacing are presented. For a fixed channel geometry, higher frequencies, deeper sources, and lower bottom absorption improve TRA performance and allow retrofocusing at longer ranges. After several minutes in a dynamic shallow-water channel containing a random superposition of linear internal waves, there is significant TRA retrofocus amplitude decay, and the decay rate increases with increasing internal wave activity and acoustic frequency. Randomness in the environment, either from bottom roughness or random linear internal waves, reduces the predicted azimuthal angular width of the vertical-TRA retrofocus to as little as a fraction of a degree (compared to 360° for uniform environments) for source-array ranges from 2.5 to 20 km at frequencies from 250 Hz to 2 kHz. In a sound channel with bottom roughness, the azimuthal size of the retrofocus is predicted to be proportional to the roughness correlation length divided by the wavenumber, source-array range, and roughness RMS-height all raised to the three-halves power. A linear TRA has three limiting orientations: vertical, endfire, and broadside. A vertical TRA is, in general, the preferred orientation. For the shortest 24 element TRA to obtain a retrofocus without large sidelobes, an endfire TRA needs to be an order of magnitude longer than a vertical TRA, while a broadside TRA requires a nearly three orders of magnitude increase in length.

Dungan, Michael Robert

2000-10-01

224

Narrow-band imaging with magnifying endoscopy is accurate for detecting gastric intestinal metaplasia  

PubMed Central

AIM: To investigate the predictive value of narrow-band imaging with magnifying endoscopy (NBI-ME) for identifying gastric intestinal metaplasia (GIM) in unselected patients. METHODS: We prospectively evaluated consecutive patients undergoing upper endoscopy for various indications, such as epigastric discomfort/pain, anaemia, gastro-oesophageal reflux disease, suspicion of peptic ulcer disease, or chronic liver diseases. Patients underwent NBI-ME, which was performed by three blinded, experienced endoscopists. In addition, five biopsies (2 antrum, 1 angulus, and 2 corpus) were taken and examined by two pathologists unaware of the endoscopic findings to determine the presence or absence of GIM. The correlation between light blue crest (LBC) appearance and histology was measured. Moreover, we quantified the degree of LBC appearance as less than 20% (+), 20%-80% (++) and more than 80% (+++) of an image field, and the semiquantitative evaluation of LBC appearance was correlated with IM percentage from the histological findings. RESULTS: We enrolled 100 (58 F/42 M) patients who were mainly referred for gastro-esophageal reflux disease/dyspepsia (46%), cancer screening/anaemia (34%), chronic liver disease (9%), and suspected celiac disease (6%); the remaining patients were referred for other indications. The prevalence of Helicobacter pylori (H. pylori) infection detected from the biopsies was 31%, while 67% of the patients used proton pump inhibitors. LBCs were found in the antrum of 33 patients (33%); 20 of the cases were classified as LBC+, 9 as LBC++, and 4 as LBC+++. LBCs were found in the gastric body of 6 patients (6%), with 5 of them also having LBCs in the antrum. The correlation between the appearance of LBCs and histological GIM was good, with a sensitivity of 80% (95%CI: 67-92), a specificity of 96% (95%CI: 93-99), a positive predictive value of 84% (95%CI: 73-96), a negative predictive value of 95% (95%CI: 92-98), and an accuracy of 93% (95%CI: 90-97). The NBI-ME examination overlooked GIM in 8 cases, but the GIM was less than 5% in 7 of the cases. Moreover, in the 6 false positive cases, the histological examination showed the presence of reactive gastropathy (4 cases) or H. pylori active chronic gastritis (2 cases). The semiquantitative correlation between the rate of LBC appearance and the percentage of GIM was 79% (P < 0.01). CONCLUSION: NBI-ME achieved good sensitivity and specificity in recognising GIM in an unselected population. In routine clinical practice, this technique can reliably target gastric biopsies.

Savarino, Edoardo; Corbo, Marina; Dulbecco, Pietro; Gemignani, Lorenzo; Giambruno, Elisa; Mastracci, Luca; Grillo, Federica; Savarino, Vincenzo

2013-01-01

225

Narrow-band measurement and analysis of the inter-vehicle transmission channel at 5.2 GHz  

Microsoft Academic Search

The inter-vehicle transmission channel is characterised based on narrow-band measurements at 5.2 GHz. The measurement setup consists of a transmitter and a receiver, which are installed in two different vehicles. While measuring the transmission channel, both vehicles are manoeuvred in realistic road traffic scenarios. Measurements are obtained for four different classes of environments: urban, suburban (village), motorway and highway. Statistical

J. Maurer; T. Fugen; W. Wiesbeck

2002-01-01

226

Endoscopic video-autofluorescence imaging followed by narrow band imaging for detecting early neoplasia in Barrett's esophagus  

Microsoft Academic Search

Background: Video-autofluorescence imaging (AFI) and narrow band imaging (NBI) are new endoscopic techniques that may improve the detection of high-grade intraepithelial neoplasia (HGIN) in Barrett's esophagus (BE). AFI improves the detection of lesions but may give false-positive findings. NBI allows for detailed inspection of the mucosal and (micro)vascular patterns, which are related to HGIN. Objective: A proof-of-principle study to combine

Mohammed A. Kara; Femke P. Peters; Paul Fockens; Fiebo J. W. ten Kate

2006-01-01

227

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

Microsoft Academic Search

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

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

2008-01-01

228

Effective Narrow-Band UVB Radiation Therapy Suppresses the IL23\\/IL17 Axis in Normalized Psoriasis Plaques  

Microsoft Academic Search

Narrow-band UVB radiation (NB-UVB) therapy offers a well-established treatment modality for psoriasis. However, despite the common use of this form of treatment, the mechanism of action of NB-UVB is not well understood. We studied a group of 14 patients with moderate-to-severe psoriasis treated with carefully titrated and monitored NB-UVB for 6 weeks. Lesional plaques were classified as normalized (n=8) or

Leanne M Johnson-Huang; Mayte Suárez-Fariñas; Mary Sullivan-Whalen; Patricia Gilleaudeau; James G Krueger; Michelle A Lowes

2010-01-01

229

Fast Medical Image Segmentation Through an Approximation of Narrow-Band B-Spline Level-Set and Multiresolution  

Microsoft Academic Search

We have recently proposed a new level-set formulation, where the level-set is modelled as a continuous parametric function expressed in a B-spline basis. We propose in this paper to adapt this formalism to the class of narrow-band level-set methods, where the implicit function evolves only around its zero-level. For this purpose, we propose to model the interface by two lists

Olivier Bernard; Denis Friboulet

2009-01-01

230

Introduction of digital narrow-band channel technology into the existing cellular spectrum in the United States  

Microsoft Academic Search

This paper shows that narrow-band digital channels of N×5 kHz bandwidth can be gracefully introduced into a fully utilized cellular spectrum. The impact of introducing this technology on system blocking levels for new digital channel users and old analog FM channel users is quantified as a function of system growth and technology migration time frame. The degree of channel reuse

Samuel W. Halpern

1987-01-01

231

Numerical Analysis of a Solar Cell with Tensile-Strained Ge as a Novel Narrow-Band-Gap Absorber  

Microsoft Academic Search

A narrow-band-gap (0.6--0.7 eV) bottom cell absorber material is one of the most important and relatively undeveloped components for future five- or six-junction solar cells. Tensile-strained Ge is a promising material for a novel bottom cell absorber since it has a high absorption coefficient and an ``adjustable'' lattice constant. In this study, we numerically demonstrate the possibility of tensile-strained Ge

Yutaka Hoshina; Masayuki Shimizu; Akira Yamada; Makoto Konagai

2011-01-01

232

Narrow cyclotron harmonic absorption resonances of stimulated electromagnetic emission in the ionosphere  

Microsoft Academic Search

Measurements are presented of stimulated electromagnetic emission (SEE) excited in the ionosphere by a powerful high-frequency ordinary mode radio wave vertically injected from a ground-based transmitter, at frequencies f(0) near high harmonics of the ionospheric electron cyclotron frequency f(c). A prominent lower-sideband SEE feature was found to be absent in an extremely narrow f(0) range of Delta f(0)\\/f(0) of about

T. B. Leyser; B. Thide; S. Goodman; M. Waldenvik; E. Veszelei; S. M. Grach; A. N. Karashtin; G. P. Komrakov; D. S. Kotik

1992-01-01

233

NaCd excimer emission bands  

NASA Astrophysics Data System (ADS)

The analysis of the visible spectrum of a high pressure sodium lamp filled with sodium, cadium and xenon revealed the existence of NaCd excimer spectral features. These are four red satellite bands at 691, 697, 709 and 726.5 nm and diffuse bands peaking at 479.1 and 484.3 nm. Both spectral phenomena are related to those found earlier for the NaHg system. An interpretation of the red satellite bands origin is given in terms of a qualitative model for the four lowest potential curves of the NaCd excimer. In this model the essential feature is the avoided crossing between B 2? 1/2 and A 2? 1/2 electronic states, which causes a complex structure of the satellite bands in the very far red wing of the sodium D lines broadened by cadmium.

Pichler, G.; Veža, D.; Fijan, D.

1988-06-01

234

NaCd excimer emission bands  

Microsoft Academic Search

The analysis of the visible spectrum of a high pressure sodium lamp filled with sodium, cadium and xenon revealed the existence of NaCd excimer spectral features. These are four red satellite bands at 691, 697, 709 and 726.5 nm and diffuse bands peaking at 479.1 and 484.3 nm. Both spectral phenomena are related to those found earlier for the NaHg

G. Pichler; D. Veza; D. Fijan

1988-01-01

235

Fast Time Resolved Spectral Analysis of VLF Banded Emissions  

Microsoft Academic Search

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

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

1971-01-01

236

Clinicopathological features of narrow-band imaging endoscopy and immunohistochemistry in ultraminute esophageal squamous neoplasms.  

PubMed

To reveal clinicopathological features of narrow-band imaging (NBI) endoscopy and immunohistochemistry in ultraminute esophageal squamous neoplasms. If a lesion diameter was smaller or same compared with a width of closed biopsy forceps, a lesion was defined to be an ultraminute lesion. Twenty-five consecutive patients with 33 ultraminute esophageal lesions that were removed by endoscopic mucosal resection were included in the present study. We conducted two questionnaire surveys of six endoscopists by their retrospective review of endoscopic still images. The six endoscopists evaluated the endoscopic findings of the ultraminute lesions on still images taken by conventional white-light imaging endoscopy and non-magnified NBI endoscopy in the first questionnaire, and taken by magnified NBI endoscopy in the second questionnaire. An experienced pathologist who was unaware of any endoscopic findings made histological diagnosis and evaluated immunoexpression of p53 and Ki67. The 33 ultraminute lesions were all determined to be either 11 high-grade intraepithelial neoplasias (HGIENs) or 22 low-grade intraepithelial neoplasias (LGIENs). The tumor diameters were histologically confirmed to be <3?mm. All of the ultraminute tumors were visualized as unstained areas and brownish areas by real-time endoscopy with Lugol dye staining and non-magnified NBI endoscopy, respectively. All of the ultraminute IENs were visualized as brownish areas by real-time non-magnified NBI endoscopy. Three of the 25 patients with the ultraminute IENs (12%) had multiple brownish areas (more than several areas) in the esophagus on real-time non-magnified NBI endoscopy. All of the ultraminute IENs were visualized as unstained areas by real-time Lugol chromoendoscopy. Twenty of the 25 patients (80%) had multiple unstained areas (more than several areas) in the esophagus on real-time Lugol chromoendoscopy. The first questionnaire survey revealed that a significantly higher detection rate of the ultraminute IENs on non-magnified NBI endoscopy images compared with conventional white-light imaging endoscopy ones (100% vs. 72%, respectively: P < 0.0001). The second questionnaire survey revealed that presence rates of any magnified NBI endoscopy findings were not significantly different between HGIENs and LGIENs. Proliferation, dilation, and various shapes of intrapapillary capillary loops indicated remarkably high presence rates of more than 90% in both HGIENs and LGIENs. Six of 22 LGIENs (27%) and 3 of 11 HGIENs (27%) show a positive expression for p53. None of peri-IEN epithelia was positive for p53. A mean of Ki67 labeling index of LGIENs was 33% and that of HGIENs 36%. Ki67 labeling index was significantly greater in the LGIENs and HGIENs compared with that in the peri-IEN epithelia. There were no significant differences in p53 expression and Ki67 labeling index between the HGIENs and LGIENs. Non-magnified/magnified NBI endoscopy could facilitate visualization and characterization of ultraminute esophageal squamous IENs. The ultraminute HGIENs and LGIENs might have comparable features of magnified NBI endoscopy and immunohistochemistry. PMID:23796261

Goda, K; Dobashi, A; Yoshimura, N; Chiba, M; Fukuda, A; Nakao, Y; Ohya, T R; Sasaki, Y; Kato, M; Aihara, H; Sumiyama, K; Toyoizumi, H; Kato, T; Tajiri, H; Ikegami, M

2014-04-01

237

Clinicopathological features of minute pharyngeal lesions diagnosed by narrow-band imaging endoscopy and biopsy  

PubMed Central

AIM: To evaluate the utility of magnified narrow-band imaging (NBI) endoscopy for diagnosing and treating minute pharyngeal neoplasia. METHODS: Magnified NBI gastrointestinal examinations were performed by the first author. A magnification hood was attached to the tip of the endoscope for quick focusing. Most of the examinations were performed under sedation. Magnified NBI examinations were performed for all of the pharyngeal lesions that had noticeable brownish areas under unmagnified NBI observation, and an intrapapillary capillary loop (IPCL) classification was made. A total of 93 consecutive pharyngeal lesions were diagnosed as IPCL type IV and were suspected to represent dysplasia. Sixty-two lesions of approximately 1 mm in diameter were biopsied in the clinic, and 17 lesions with larger diameters were resected by endoscopic submucosal dissection (ESD) at the Hiroshima University Hospital. In addition to the histological diagnoses, the lesion diameters were microscopically measured in 45 of the 62 biopsies. Thirty-four of the 62 biopsied patients received endoscopic follow up. RESULTS: Minute pharyngeal lesions were diagnosed in 93 of approximately 3000 patients receiving magnified NBI examinations at the clinic. Of the 93 patients with IPCL type IV lesions, 80 were men, and 13 were women. Fifty-six were drinkers, and 57 were smokers. Two had esophageal cancer. Twenty-one lesions were located on the posterior hypopharyngeal wall, and 72 lesions were located on the posterior oropharyngeal wall. All 93 lesions were flat and showed similar findings in the magnified and unmagnified NBI examinations. Although almost all of the IPCL type IV lesions showed faint redness when examined under white light, it was difficult to diagnose the lesions using only this technique because the contrast was weaker than that achieved in the NBI examinations. Of the 93 lesions, only 3 had diameters greater than 2.1 mm. Sixty-two lesions of approximately 1 mm were biopsied in the clinic, whereas 17 larger lesions were treated by ESD at the Hiroshima University Hospital. Of the 79 pharyngeal lesions that were biopsied or resected by ESD, 5 were histologically diagnosed as high-grade dysplasia, 39 were diagnosed as low-grade dysplasia, and 39 were determined to be non-dysplastic lesions. There were no cancerous lesions. Histologically, abnormal cell size variations and increased nuclear size were observed in all of the high-grade dysplasia lesions, while the incidence of these findings in the low-grade dysplasia lesions was low. Of the 62 biopsied lesions, 45 were microscopically measurable. The measured diameters ranged from 0.1 to 2.0 mm. The dysplasia ratios increased with the diameters. A follow-up endoscopic examination of the 34 biopsied patients found the rate of complete resection by biopsy to be 79%. The largest lesion in which complete resection was expected was a low-grade dysplasia of 1.9 mm in diameter. CONCLUSION: Minute pharyngeal lesions suspected to be dysplasia that are identified by NBI magnifying endoscopy should be biopsied to determine the diagnosis and further treatment.

Kumamoto, Takashi; Sentani, Kazuhiro; Oka, Shiro; Tanaka, Shinji; Yasui, Wataru

2012-01-01

238

Quantum mazes: luminescent labyrinthine semiconductor nanocrystals having a narrow emission spectrum.  

PubMed

We exploit the polytypism of group II-VI semiconductors and the long-range dipolar interactions typical of CdSe nanoparticle formation to modulate the geometrical structure and the optical emission properties of novel branched CdSe nanocrystals through shape-dependent quantum confinement effects. X-ray diffraction confirms that these materials incorporate crystalline domains of cubic zinc-blende and hexagonal wurtzite within a polycrystalline growth form whose geometry can be controlled by varying thermodynamic conditions. In particular, labyrinthine-shaped nanoparticles of tunable dimensions are reproducibly synthesized based on a heterogeneous reaction between cadmium acetate in a solution in hexadecylamine and trioctylphosphine with Se as a solid precursor at a relatively low temperature (110 degrees C). The resulting highly branched CdSe structures resemble labyrinthine patterns observed in magnetic fluids and superconductors films in magnetic fields, and in lipid films and other materials where strong dipolar interactions "direct" large-scale pattern formation. Surprisingly, these novel maze-like structures emit light within a narrow bandwidth (full-width at half-maximum approximately equal to 33-42 nm) of the visible spectrum (508 nm < lambda < 563 nm), so the regular dimensions of the core regions of these branched structures govern their emission characteristics rather than overall nanoparticle size. This property should make these materials attractive for applications where luminescent materials having tunable emission characteristics and a narrow emission frequency range are required, along with the insensitivity of the particles' luminescent properties to environmental conditions. PMID:19206685

De Paoli Lacerda, Silvia H; Douglas, Jack F; Hudson, Steven D; Roy, Marc; Johnson, Jerainne M; Becker, Matthew L; Karim, Alamgir

2007-11-01

239

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

240

Narrow-band photometry of Early-type stars (Morguleff+, 1975)  

NASA Astrophysics Data System (ADS)

A compilation of the photoelectric measurements in the Barbier-Morguleff system is presented for 773 stars of spectral types O8 to F6. 706 stars have been measured at least twice. The passbands (in Angstroems) and the mean photometric errors of the indexes C(j)-C(2) (in magnitudes) are: ----------------------- Band Interval m.e. ----------------------- C(1) 6000-5900 0.0318 C(2) 5000-4900 --- C(3) 4905-4815 0.0073 C(4) 4380-4310 0.0100 C(5) 4070-4010 0.0102 C(6) 3965-3925 0.0201 C(7) 3780-3720 0.0195 C(8) 3650-3575 0.0189 ----------------------- Regarding the catalog Pass Bands Morguleff and Gerbaldi (1975) note the following: These spectral intervals permit the determination of certain physical characteristics .... The pass bands 1 and 5 lead us to calculate red and blue gradients. The equivalent widths of the H(beta), H(gamma) lines of hydrogen and the K lines of Ca II are derived from band 3, 4, and 6. Bands 7 and 8 measure the Balmer jump. Listed in the catalog file are the normalized magnitudes corresponding to the above pass bands. The normalized magnitude of a pass band, C(j), is defined as the color index of the magnitude in the band minus the magnitude of the second band, C(2). See Morguleff and Gerbaldi (1975) for a brief discussion of conservation of the system and mean errors across all stars. (1 data file).

Morguleff, N.; Gerbaldi, M.

1995-03-01

241

[Early detection of recurrent hypopharyngeal cancer after radiotherapy by utilizing narrow-band imaging--report of a case].  

PubMed

Narrow-band Imaging (NBI) is a novel optical technique in which the diagnostic capability of endoscopes in characterizing tissue is enhanced by the use of narrow-bandwidth filters in the video endoscope system. We report a case of early recurrence of hypopharyngeal cancer after radical radiotherapy which was detected by laryngoscopy using NBI. A 66-year-old man with right pyriform sinus cancer was treated by radical radiotherapy in March 2004. Twenty months later, laryngoscopy using NBI revealed an abnormal lesion in the right pyriform sinus, visualized as scattered brownish dots, which highly suggestive of a malignant lesion. After obtaining written informed consent from the patient, endoscopic mucosal resection of the lesion was performed. Histological examination of the resected specimen revealed a squamous cell carcinoma in situ. The patient did not need any additional therapy. Laryngoscopy using NBI appears to have good potential to detect early stage local tumor recurrence after radical radiotherapy. PMID:18018596

Watanabe, Akihito; Taniguchi, Masanobu; Tsujie, Hitoshi; Fujita, Masahiro; Sasaki, Shigeyuki

2007-10-01

242

Tunable narrow-band coherent VUV source for the lyman-alpha region  

Microsoft Academic Search

The output from a butyl-PBD dye laser, pumped by a nitrogen laser or a KrF excimer laser, has been frequency tripled in krypton gas to generate coherent Lyman-alpha radiation. A tuning range of 1203-1236 Å was obtained, with high output power (up to 5 W, 1010 photons\\/pulse) and narrow bandwidth (4 x 10-3 Å).

David Cotter

1979-01-01

243

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

PubMed Central

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

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

2012-01-01

244

Optimized design of a band-pass filter with low frequency and narrow bandwidth  

NASA Astrophysics Data System (ADS)

An underwater metal pipeline detector is designed based on the principle of artificial source electromagnetic detection, which is used for detecting the deeply buried in underwater metal pipes. Narrowband band-pass filter in the receiver can well separate the specific frequency signal from mixed signal which is containing strong noise. Authors deduced the narrowband filter transfer function and simulated in computer, and the detector was applied in instrument prototype. Experiment results show that the error of the center frequency of the band-pass filter is small, and the gain is stable. In conclusion the detector has good performance.

Tian, Biao; Fu, Guo-hong; Liao, Xiu-ying; Cheng, Hui; Li, Guang

2013-10-01

245

VARIATIONAL APPROACH TO FINITE-TEMPERATURE MAGNETISM IN THE DEGENERATE NARROW BANDS  

Microsoft Academic Search

The variational approach which describes the local electron correlations at finite temperatures has been extended to the degenerate-band case. It reduces Tc in the static approximation by a factor of two, gives realistic Tc between the observed value Tc (Obs) and 2Tc (Obs) , and suppresses the temperature independent charge fluctuation in Fe and Ni. The finite-temperature theories of magnetism

Y. Kakehashi

1988-01-01

246

Effects of Electron-Electron and Electron-Phonon Interactions in Narrow-Band Systems  

Microsoft Academic Search

Different ordered states, CDW, BOW, and SDW, are investigated theoretically for both interacting and noninteracting cases as well as for different band filling systems. For noninteracting case, we find that the BOW is always accompanied by the CDW and vice versa in one-dimensional system for commensurability > 2. The strong electron -molecular vibration coupling drives both CDW and BOW, and

Kim-Chau Ung

1994-01-01

247

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

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

248

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

NASA Technical Reports Server (NTRS)

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

Horowitz, Paul; Sagan, Carl

1993-01-01

249

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

250

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

SciTech Connect

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

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

2011-01-01

251

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

NASA Astrophysics Data System (ADS)

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

Liang, Shuhua; Daghofer, Maria; Dong, Shuai; ?en, Cengiz; Dagotto, Elbio

2011-07-01

252

The split symbol moments SNR estimator in narrow-band channels  

NASA Technical Reports Server (NTRS)

The split symbol moments estimator is an algorithm that is designed to estimate symbol SNR in the presence of additive white Gaussian noise. The performance of the algorithm in band-limited channels is examined, and the effects of the resulting intersymbol interference are quantified. All results obtained are in closed form and can be easily evaluated numerically for performance-prediction purposes. The results are also validated through digital simulations.

Shah, Biren; Hinedi, Sami

1990-01-01

253

Suppression of electron-phonon interaction in narrow-band crystals  

Microsoft Academic Search

Taking the inelastic nature of the interaction of electrons with acoustic phonons into account is crucial in crystals having\\u000a a conduction band width ?? comparable to the maximum acoustic phonon energy\\u000a $$\\\\bar \\\\varepsilon $$\\u000a . In view of this, the laws of conservation of energy and wave vector impose stringent constraints on possible electron scattering\\u000a processes, and single-phonon scattering becomes

O. V. Kibis

1997-01-01

254

100% efficient narrow-band acoustooptic tunable reflector using fiber Bragg grating  

Microsoft Academic Search

This paper reports a 100% efficient Bragg-grating-based acoustooptic superlattice modulator in a fiber whose diameter is reduced by HF etching. The acoustically induced reflections, which appear on both sides of the Bragg stop-band, are tunable by altering the acoustic frequency, and have bandwidths corresponding to weak versions of the permanent Bragg grating. These unique properties may lead to important applications

W. F. Liu; P.St.J. Russell; L. Dong

1998-01-01

255

Follow-up Observations of Transiting Exoplanets with High-Precision Narrow-band Photometry  

Microsoft Academic Search

Ground and space-based exoplanet searches have already discovered several Neptune-size planets and are rapidly closing in on ``Super-Earths'' and ultimately Earth-like planets. For planets that transit their host stars, follow-up photometric observations enable the characterization of the planet's physical and orbital properties. Traditionally, ground-based photometry is performed using broad-band filters to maximize throughput and minimize photon noise. For high-precision ground-based

Eric B. Ford; K. D. Colon; C. Blake; B. L. Lee; S. Mahadevan

2009-01-01

256

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

257

Infrared Fe II Emission in Narrow-Line Seyfert 1 Galaxies  

NASA Astrophysics Data System (ADS)

We obtained 0.8-2.4 ?m spectra at a resolution of 320 km s-1 of four narrow-line Seyfert 1 galaxies in order to study the near-infrared properties of these objects. We focus on the analysis of the Fe II emission in that region and the kinematics of the low-ionization broad lines. We show that the 1 ?m Fe II lines (?9997, ?10501, ?10863, and ?11126) are the strongest Fe II lines in the observed interval. For the first time, primary cascade lines of Fe II arising from the decay of upper levels pumped by Ly? fluorescence are resolved and identified in active galactic nuclei. Excitation mechanisms leading to the emission of the 1 ?m Fe II features are discussed. A combination of Ly? fluorescence and collisional excitation is found to be the main contributor. The flux ratio between near-IR Fe II lines varies from object to object, in contrast to what is observed in the optical region. A good correlation between the 1 ?m and optical Fe II emission is found. This suggests that the upper z4F0 and z4D0 levels from which the bulk of the optical Fe II lines descend are mainly populated by the transitions leading to the 1 ?m lines. The width and profile shape of Fe II ?11127, Ca II ?8642, and O I ?8446 are very similar but significantly narrower than Pa?, giving strong observational support to the hypothesis that the regions where Fe II, Ca II, and O I are produced are cospatial, interrelated kinematically, and most probably located in the outermost portion of the broad-line region.

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

2002-01-01

258

Control of spontaneous emission from an RF-driven five-level atom in an anisotropic double-band photonic-band-gap reservoir  

NASA Astrophysics Data System (ADS)

The control of spontaneous emission from an radio-frequency (RF)-driven five-level atom embedded in a three-dimensional photonic crystal is investigated by considering the anisotropic double-band photonic-band-gap (PBG) reservoir. It is shown that, due to the coexistence of the PBG and the quantum interference effect induced by the RF-driven field, some interesting features, such as the spectral-line narrowing, the spectral-line enhancement, the spectral-line suppression and the occurrence of a dark line in spontaneous emission, can be realized by adjusting system parameters under the experimentally available parameter conditions. The proposed scheme can be achieved by use of an RF-driven field into hyperfine levels in rubidium atom confined in a photonic crystal. These theoretical investigations may provide more degrees of freedom to vary the spontaneous emission.

Ding, C.; Li, J.; Yang, X.

2011-06-01

259

Narrow Band Photometry of the Calcium H and K lines for Stars in Open Clusters  

NASA Astrophysics Data System (ADS)

The Ca II K line and the blend of the Ca II H line with H? are strong indicators of spectral type and are useful in the study of open clusters. Two narrow filters have been fabricated to image separately in the regions of these two lines. The filters are centered at 393.4 nm and 396.9 nm respectively, with each being 3.0 nm wide. We will present two sets of observations; 1) spectroscopic data in the region of Calcium HK over a range of spectral types, and 2) the first photometric images through the new filters. The spectroscopic observations were taken with the 1.2-m telescope of the Dominion Astrophysical Observatory. While the photometric observations were obtained with the 0.4-m David Derrick telescope of the Orson Pratt Observatory. The authors would like to acknowledge the support of an AAS Small Research Grant for the purchase of the filters and for travel to DAO. The authors would also like to thank DAO for the use of the 1.2-m telescope.

Hintz, E. G.; Rose, M. B.

2004-12-01

260

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

261

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.

2013-12-01

262

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

NASA Astrophysics Data System (ADS)

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 61S to 71S 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 61P 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.; Steel, D. G.; Remillard, J.

1988-10-01

263

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

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

264

Assessment of MODIS Thermal Emissive Band On-Orbit Calibration  

NASA Technical Reports Server (NTRS)

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

Chang, Tiejun; Xiong, Xiaoxiong

2011-01-01

265

Strong Narrow-Band Luminescence from Silicon-Vacancy Color Centers in Spatially Localized Sub-10 nm Nanodiamond  

PubMed Central

Discrete nanodiamond particles of 500 nm and 6 nm average size were seeded onto silicon substrates and plasma treated using chemical vapor deposition to create silicon-vacancy color centers. The resulting narrow-band room temperature photoluminescence is intense, and readily observed even for weakly agglomerated sub-10 nm size diamond. This is in contrast to the well-studied nitrogen-vacancy center in diamond which has luminescence properties that are strongly dependant on particle size, with low probability for incorporation of centers in sub-10 nm crystals. We suggest the silicon-vacancy center to be a viable alternative to nitrogen-vacancy defects for use as a biomarker in the clinically-relevant sub-10 nm size regime, for which nitrogen defect-related luminescent activity and stability is reportedly poor.

Catledge, Shane A.; Singh, Sonal

2011-01-01

266

Strong Narrow-Band Luminescence from Silicon-Vacancy Color Centers in Spatially Localized Sub-10 nm Nanodiamond.  

PubMed

Discrete nanodiamond particles of 500 nm and 6 nm average size were seeded onto silicon substrates and plasma treated using chemical vapor deposition to create silicon-vacancy color centers. The resulting narrow-band room temperature photoluminescence is intense, and readily observed even for weakly agglomerated sub-10 nm size diamond. This is in contrast to the well-studied nitrogen-vacancy center in diamond which has luminescence properties that are strongly dependant on particle size, with low probability for incorporation of centers in sub-10 nm crystals. We suggest the silicon-vacancy center to be a viable alternative to nitrogen-vacancy defects for use as a biomarker in the clinically-relevant sub-10 nm size regime, for which nitrogen defect-related luminescent activity and stability is reportedly poor. PMID:21603120

Catledge, Shane A; Singh, Sonal

2011-02-01

267

Band Narrowing and Mott Localization in Iron Oxychalcogenides La2O2Fe2O(Se,S)2  

NASA Astrophysics Data System (ADS)

Bad metal properties have motivated a description of the parent iron pnictides as correlated metals on the verge of Mott localization. What has been unclear is whether interactions can push these and related compounds to the Mott-insulating side of the phase diagram. Here we consider the iron oxychalcogenides La2O2Fe2O(Se,S)2, which contain an Fe square lattice with an expanded unit cell. We show theoretically that they contain enhanced correlation effects through band narrowing compared to LaOFeAs, and we provide experimental evidence that they are Mott insulators with moderate charge gaps. We also discuss the magnetic properties in terms of a Heisenberg model with frustrating J1-J2-J2' exchange interactions on a “doubled” checkerboard lattice.

Zhu, Jian-Xin; Yu, Rong; Wang, Hangdong; Zhao, Liang L.; Jones, M. D.; Dai, Jianhui; Abrahams, Elihu; Morosan, E.; Fang, Minghu; Si, Qimiao

2010-05-01

268

Determination of the neutron star mass-radii relation using narrow-band gravitational wave detector  

NASA Astrophysics Data System (ADS)

The direct detection of gravitational waves will provide valuable astrophysical information about many celestial objects. The most promising sources of gravitational waves are neutron stars and black holes. These objects emit waves in a very wide spectrum of frequencies determined by their quasi-normal modes oscillations. In this work we are concerned with the information we can extract from f and pI-modes when a candidate leaves its signature in the resonant mass detectors ALLEGRO, EXPLORER, NAUTILUS, MiniGrail and SCHENBERG. Using the empirical equations, that relate the gravitational wave frequency and damping time with the mass and radii of the source, we have calculated the radii of the stars for a given interval of masses M in the range of frequencies that include the bandwidth of all resonant mass detectors. With these values we obtain diagrams of mass-radii for different frequencies that have allowed to determine the better candidates to future detection taking in account the compactness of the source. Finally, to determine which are the models of compact stars that emit gravitational waves in the frequency band of the mass resonant detectors, we compare the mass-radii diagrams obtained by different neutron stars sequences from several relativistic hadronic equations of state (GM1, GM3, TM1, NL3) and quark matter equations of state (NJL, MTI bag model). We verify that quark stars obtained from MIT bag model with bag constant equal to 170 MeV and quark matter in color-superconductivity phase are the best candidates for mass resonant detectors.

Lenzi, C. H.; Malheiro, M.; Marinho, R. M.; Marranghello, G. F.; Providência, C.

2009-03-01

269

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

270

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

271

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

272

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

273

Narrow band imaging in the diagnosis of intra-epithelial and invasive laryngeal squamous cell carcinoma: A preliminary report of two cases  

Microsoft Academic Search

Narrow band imaging (NBI) is a novel optical technique that enhances the diagnostic capability of the gastrointestinal endoscope (GIE) by illuminating the intraepithelial papillary capillary loop (IPCL) using narrow bandwidth filters in a red-green-blue sequential illumination system (CV-260SL processor and CLV-260SL light source, Olympus Optical Co. Ltd, Tokyo, Japan). The NBI filter sets (415nm and 540nm) are selected to obtain

Takashi Masaki; Chikatoshi Katada; Meijin Nakayama; Masahiko Takeda; Shunsuke Miyamoto; Yutomo Seino; Wasaburo Koizumi; Satoshi Tanabe; Satoshi Horiguchi; Makito Okamoto

2009-01-01

274

Broad-band emission from chromium doped germanium garnets  

Microsoft Academic Search

By varying the composition of a series of germanium garnets, it is possible to change the lattice constant of the structure over a wide range, and thus the crystal field. Three Cr-doped germanium garnets (CaâAlâGeâthetaââ, CaYâMgâGeâthetaââ, and MgYâMgâGeâtheta ââ) have been grown as single crystals. Spectroscopic results show that in these garnets the broad-band emission at room temperature is so

H. P. Christensen; H. P. Jenssen

1982-01-01

275

Progenitor constraints on the Type-Ia supernova SN2011fe from pre-explosion Hubble Space Telescope He II narrow-band observations  

NASA Astrophysics Data System (ADS)

We present Hubble Space Telescope (HST) imaging observations of the site of the Type-Ia supernova SN2011fe in the nearby galaxy M101, obtained about 1 yr prior to the event, in a narrow band centred on the He II ?4686 Å emission line. In a `single-degenerate' progenitor scenario, the hard photon flux from an accreting white dwarf (WD), burning hydrogen on its surface over ˜1 Myr should, in principle, create a He III Strömgren sphere or shell surrounding the WD. Depending on the WD luminosity, the interstellar density, and the velocity of an outflow from the WD, the He III region could appear unresolved, extended, or as a ring, with a range of possible surface brightnesses. We find no trace of He II ?4686 Å line emission in the HST data. Using simulations, we set 2? upper limits on the He II ?4686 Å luminosity of LHe II < 3.4 × 1034 erg s-1 for a point source, corresponding to an emission region of radius r < 1.8 pc. The upper limit for an extended source is LHe II < 1.7 × 1035 erg s-1, corresponding to an extended region with r ˜ 11 pc. The largest detectable shell, given an interstellar-medium density of 1 cm-3, has a radius of ˜6 pc. Our results argue against the presence, within the ˜105 yr prior to the explosion, of a supersoft X-ray source of luminosity Lbol ? 3 × 1037 erg s-1, or of a super-Eddington accreting WD that produces an outflowing wind capable of producing cavities with radii of 2-6 pc.

Graur, Or; Maoz, Dan; Shara, Michael M.

2014-04-01

276

Progenitor constraints on the Type-Ia supernova SN2011fe from pre-explosion Hubble Space Telescope He II narrow-band observations  

NASA Astrophysics Data System (ADS)

We present Hubble Space Telescope (HST) imaging observations of the site of the Type-Ia supernova SN2011fe in the nearby galaxy M101, obtained about 1 yr prior to the event, in a narrow band centred on the He II ?4686 Å emission line. In a `single-degenerate' progenitor scenario, the hard photon flux from an accreting white dwarf (WD), burning hydrogen on its surface over ˜1 Myr should, in principle, create a He III Strömgren sphere or shell surrounding the WD. Depending on the WD luminosity, the interstellar density, and the velocity of an outflow from the WD, the He III region could appear unresolved, extended, or as a ring, with a range of possible surface brightnesses. We find no trace of He II ?4686 Å line emission in the HST data. Using simulations, we set 2? upper limits on the He II ?4686 Å luminosity of LHe II < 3.4 × 1034 erg s-1 for a point source, corresponding to an emission region of radius r < 1.8 pc. The upper limit for an extended source is LHe II < 1.7 × 1035 erg s-1, corresponding to an extended region with r ˜ 11 pc. The largest detectable shell, given an interstellar-medium density of 1 cm-3, has a radius of ˜6 pc. Our results argue against the presence, within the ˜105 yr prior to the explosion, of a supersoft X-ray source of luminosity Lbol ? 3 × 1037 erg s-1, or of a super-Eddington accreting WD that produces an outflowing wind capable of producing cavities with radii of 2-6 pc.

Graur, Or; Maoz, Dan; Shara, Michael M.

2014-07-01

277

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

NASA Astrophysics Data System (ADS)

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

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

2003-04-01

278

High-resolution spectra of distant compact narrow emission line galaxies: Progrenitors of spheroidal galaxies  

NASA Technical Reports Server (NTRS)

Emission-line velocity widths have been determined for 17 faint (B approximately 20-23) very blue, compact galaxies whose redshifts range from z = 0.095 to 0.66. The spectra have a resolution of 8 Km/s and were taken with the HIRES echelle spectrograph of the Keck 10 m telescope. The galaxies are luminous with all but two within 1 mag of M(sub B) approximately -21. Yet they exhibit narrow velocity widths between sigma = 28-157 km/s, more consistent with typical values of extreme star-forming galaxies than with those of nearby spiral galaxies of similar luminosity. In particular, objects with sigma is less than or equal to 65 km/s follow the same correlations between sigma and both blue and H beta luminosities as those of nearby H II galaxies. These results strengthen the identification of H II glaxies as thier local counterparts. The blue colors and strong emission lines suggest these compact galaxies are undergoing a recent, strong burst of star formation. Like those which characterize some H II galaxies, this burst could be a nuclear star-forming event within a much larger, older stellar population. If the burst is instead a major episode in the total star-forming history, these distant galaxies could fade enough to match the low luminosities and surface brightnesses typical of nearby spheroidals like NGC 185 or NGC 205. Together with evidence for recent star formation, exponential light profiles, and subsolar metallicities, the postfading correlations between luminosity and velocity width and bewtween luminosity and surface brightness suggest that among the low-sigma galaxies, we may be witnessing, in situ, the progenitors of today's spheroidal galaxies.

Koo, David C.; Guzman, Rafael; Faber, S. M.; Illingworth, Garth D.; Bershady, Matthew A.; Kron, Richard G.; Takamiya, Marianne

1995-01-01

279

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

Microsoft Academic Search

The Midcourse Space Experiment (MSX) has surveyed the Galactic plane in four infrared bands between 6 and 25 mu m. Two of these bands cover several Unidentified Infrared emission Bands (UIBs). With the aim of extracting the spatial distribution of the UIB emission on a large scale, a scheme has been developed to model the MSX data with emission in

S. K. Ghosh; D. K. Ojha

2002-01-01

280

Preparation of narrow band gap V2O5/TiO2 composite films by micro-arc oxidation  

NASA Astrophysics Data System (ADS)

V2O5/TiO2 composite films were prepared on pure titanium substrates via micro-arc oxidation (MAO) in electrolytes consisting of NaVO3. Their morphology and elements were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis. Phase composition and valence states of species in the films were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS) were also employed to evaluate the photophysical property of the films. The V2O5/TiO2 composite films show a sheet-like morphology. Not only V2O5 phase appears in the films when the NaVO3 concentration of the electrolyte is higher than 6.10 g/L and is loaded at the surface of anatase, but also V4+ is incorporated into the crystal lattice of anatase. In comparison with pure TiO2 films the V2O5/TiO2 composite films exhibit significantly narrow band gap energy. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the narrowest band gap energy, which is approximately 1.89 eV. The V2O5/TiO2 composite films also have the significantly enhanced visible light photocatalytic activity. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the best photocatalytic activity and about 93% of rhodamine is degraded after 14 h visible light radiation.

Luo, Qiang; Li, Xin-wei; Cai, Qi-zhou; Yan, Qing-song; Pan, Zhen-hua

2012-11-01

281

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

282

Observer Variability in Gastric Neoplasm Assessment Using the Vessel Plus Surface Classification for Magnifying Endoscopy with Narrow Band Imaging  

PubMed Central

Background/Aims Recent studies have demonstrated that magnifying endoscopy with narrow band imaging (ME-NBI) facilitates differentiation of early gastric cancer from gastric adenoma using vessel plus surface (VS) classification. This study estimated the interobserver and intraobserver agreement of endoscopists using the Yao VS classification system for the gastric mucosal surface. Methods We retrospectively reviewed patients who underwent endoscopic submucosal dissection or endoscopic mucosal resection, and selected cases in which preoperative ME-NBI was conducted. Before testing endoscopists, a 20-minute training module was given. Static ME-NBI images (n=47 cases) were presented to seven endoscopists (two experts and five trainees) who were asked to assess the images in 20 seconds using the Yao VS classification system. After 2 weeks, the endoscopists were asked to analyze the images again. The ? statistic was calculated for intraobserver and interobserver variability. Results The mean ? for intraobserver agreement was 0.69 (experts, 0.74; trainees, 0.64). The mean ? for interobserver agreement was 0.42 (experts, 0.49; trainees, 0.40). Conclusions We obtained reliable results as assessed by observer variability, with only brief training on VS classification. The VS classification appears to provide an objective assessment of ME-NBI for trainees who are not familiar with ME-NBI.

Yoo, Chan Hui; Park, Seun Ja; Moon, Won; Kim, Hyung Hun; Song, Jun Young; Kim, Do Hyun

2014-01-01

283

Narrow band imaging and high definition television in the assessment of laryngeal cancer: a prospective study on 279 patients.  

PubMed

Narrow band imaging (NBI) is an optical technique in which a filtered light reveals superficial carcinomas in view of their neoangiogenic pattern. The accuracy of NBI is implemented by combining it with a high definition television (HDTV) camera. The aim of this study was to prospectively evaluate the diagnostic gain of NBI and HDTV in the assessment of laryngeal squamous cell carcinoma (LSCC). Between April 2007 and December 2008, we analyzed by NBI with or without HDTV 279 patients divided in two groups: Group A included 96 patients affected by LSCC and Group B included 183 subjects under follow-up after treatment for the same disease. Overall, 50 of 279 patients (18%) showed "suspicious" NBI findings histologically confirmed as neoplastic. The sensitivity, specificity, accuracy, positive and negative predictive rates of flexible NBI, HDTV with white light, and HDTV with NBI in both groups confirmed the value of these two technologies. In the pre- and intraoperative settings, NBI with or without HDTV provided better definition of tumor staging and surgical margins. NBI has also a role in the postoperative setting, due to its ability in early detection of persistences, recurrences, and metachronous tumors. PMID:19826829

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

2010-03-01

284

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

285

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

286

Dynamics of a narrow-band exciton coupled with optical phonons: A time-convolutionless master-equation approach  

NASA Astrophysics Data System (ADS)

A time-convolutionless master equation is established for studying the dynamics of a narrow-band exciton coupled with optical phonons. Within the nonadiabatic weak-coupling limit, the diagonal hypothesis works quite well so that the exciton-phonon dynamics is mainly governed by the so-called time-dependent dephasing function. It has been shown that the dephasing function tends to zero by exhibiting damped oscillations that characterize a series of dephasing-rephasing mechanisms. Indeed, the correlation time of the exciton-phonon interaction is defined as the time needed to the exciton to cover a few lattice sites. Therefore this correlation time is sufficiently long so that the system dynamics remains sensitive to the coherent nature of the lattice vibrations. Because the phonon memory recurs periodically, the exciton experiences a series of dephasing-rephasing processes. Although each rephasing does not exactly compensate the previous dephasing, the coherence survives. Consequently, the exciton keeps its wavelike nature and a coherent energy transfer occurs according to an effective hopping constant smaller than the bare hopping constant.

Pouthier, Vincent

2009-10-01

287

Effective narrow-band UVB radiation therapy suppresses the IL-23/IL-17 axis in normalized psoriasis plaques.  

PubMed

Narrow-band UVB radiation (NB-UVB) therapy offers a well-established treatment modality for psoriasis. However, despite the common use of this form of treatment, the mechanism of action of NB-UVB is not well understood. We studied a group of 14 patients with moderate-to-severe psoriasis treated with carefully titrated and monitored NB-UVB for 6 weeks. Lesional plaques were classified as normalized (n=8) or nonresponsive (n=6) based on their histological improvement and normalization. We characterized lesional myeloid dendritic cells (DCs) and T cells and their inflammatory mediators using immunohistochemistry and real-time PCR. NB-UVB suppressed multiple parameters of the IL-23/IL-17 pathway in normalized plaques, but not in nonresponsive plaques. NB-UVB decreased the numbers of CD11c(+) DCs, specifically CD1c(-)CD11c(+) "inflammatory" DCs, and their products, IL-20, inducible nitric oxide synthase, IL-12/23p40, and IL-23p19. Furthermore, effective NB-UVB suppressed IL-17 and IL-22 mRNAs, which strongly correlated with lesion resolution. Therefore, in addition to its known role in suppressing IFN-? production, NB-UVB radiation therapy can also target the IL-17 pathway to resolve psoriatic inflammation.JID JOURNAL CLUB ARTICLE: For questions, answers, and open discussion about this article, please go to http://www.nature.com/jid/journalclub. PMID:20555351

Johnson-Huang, Leanne M; Suárez-Fariñas, Mayte; Sullivan-Whalen, Mary; Gilleaudeau, Patricia; Krueger, James G; Lowes, Michelle A

2010-11-01

288

Eu3+-activated Y2MoO6: a narrow band red-emitting phosphor with strong near-UV absorption.  

PubMed

Near-UV excited narrow line red-emitting phosphors, Eu(3+)-activated Y2MoO6 systems, were synthesized using a simple molten salt reaction. The structure and photoluminescence characteristics were investigated using X-ray powder diffraction, UV-Vis absorption and fluorescent spectrophotometry. The excitation spectra show strong broad-band absorptions in the near-UV to blue light regions which match the radiation of near-UV light-emitting diode chips well. Under excitation of either near-UV or blue light, intense red emission with a main peak of 611 nm is observed, ascribed to the (5)D0-(7)F2 transition of Eu(3+) ions; the optimal doping concentration is 20 mol%. The chromaticity coordinates (x = 0.65, y = 0.34) of the as-obtained phosphor are very close to the National Television Standard Committee standard values (x = 0.67, y = 0.33). All these characteristics suggest that this material is a promising red-emitting phosphor candidate for white-LEDs based on near-UV LED chips. PMID:23124929

He, Xianghong; Bian, Danping; Wang, Hao; Xu, Jian

2013-01-01

289

Narrow band imaging in the diagnosis of intra-epithelial and invasive laryngeal squamous cell carcinoma: a preliminary report of two cases.  

PubMed

Narrow band imaging (NBI) is a novel optical technique that enhances the diagnostic capability of the gastrointestinal endoscope (GIE) by illuminating the intraepithelial papillary capillary loop (IPCL) using narrow bandwidth filters in a red-green-blue sequential illumination system (CV-260SL processor and CLV-260SL light source, Olympus Optical Co. Ltd, Tokyo, Japan). The NBI filter sets (415 nm and 540 nm) are selected to obtain fine images of the microvascular structure. Because 415 nm is the hemoglobin absorption band, capillaries on the mucosal surface can be seen most clearly at this wavelength. NBI is able to represent more clearly both capillary patterns and the boundary between different types of tissue, which are necessary for diagnosing a tumor in its early stage (Gono K, Yamazaki K, Doguchi N, Nonami T, Obi T, Yamaguchi M, et al. Endoscopic observation of tissue by narrow band illumination. Opt Rev 2003;10:211-215, Gono K, Obi T, Yamaguchi M, Ohyama N, Machida H, Sano Y, et al. Appearance of enhanced tissue feature in narrow-band endoscopic imaging. J Biomed Opt 2004;9:568-577). We present two patients with laryngeal squamous cell carcinoma in whom the spread and the depth of invasion was evaluated with transnasal GIE equipped with NBI. Based on our results, the vascular neoplastic changes of carcinoma in situ of the larynx could be similar to carcinoma in situ of the esophagus. PMID:19261406

Masaki, Takashi; Katada, Chikatoshi; Nakayama, Meijin; Takeda, Masahiko; Miyamoto, Shunsuke; Seino, Yutomo; Koizumi, Wasaburo; Tanabe, Satoshi; Horiguchi, Satoshi; Okamoto, Makito

2009-12-01

290

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

291

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

292

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

293

Simultaneous multi-spectral narrow-band auroral imagery from space (1150A to 6300A2)  

SciTech Connect

The design of a multi-mode instrument known as the Auroral Ionospheric Remote Sensor, AIRS, is described. The goal of the AIRS instrument is to produce data on the global imaging of the auroral display in both dark and sunlit hemispheres with the remote sensing of ionospheric airglows to deduce ionospheric parameters such as electron-density profiles and atmospheric background emissions. The AIRS will fly on a the POLAR BEAR spacecraft in a near-polar circular orbit at an altitude of 1000 km with a scheduled launch in the fall of 1986. The AIRS instrument is designed as a multi-mode system with four (4) channels of data to yield simultaneous operation in the vacuum ultraviolet (VUV), near ultraviolet (UV), and visible spectral bands. Two of the data channels are designed to operate in the VUV with 30A windows having a 240A separation. These two channels utilize an Ebert-Fastile spectrometer which can provide total coverage for each of these channels from 1150A to 1800A. The other two channels utilize a filter selector system to provide preselected, 10A bandwidth spectral channels at 3371A, 3914A, and 6300A, and a 200A wide channel centered at 2250A. These spectral bands are paired to provide simultaneous pair coverage of 2250A and 3371A and simultaneous pair coverage of 3914A and 6300A. All four channels view the auroral scene of the north polar cap via appropriate optics and scan mirror system. In effect, a line-scan image of the auroral scene is produced via the scan mirror operating in the orbit cross plane with the longitudinal direction provided by the forward motion of the spacecraft.

Schenkel, F.W.; Ogorzalek, B.S.; Gardner, R.R.; Hutchins, R.A.; Huffman, R.E.

1986-01-01

294

Ultrafast intensity-dependent stimulated emission in conjugated polymers: The mechanism for line-narrowing  

Microsoft Academic Search

Intensity-dependent, time-resolved stimulated emission experiments are performed simultaneously with emission line width measurements on the conjugated polymer BCHA–PPV. The results show a steady decrease in emission lifetime with increasing excitation intensity, consistent with a model utilizing only stimulated emission. No evidence is found for condensed excitonic species or coherent emission processes such as superfluorescence. The spatially anisotropic nature of the

Vinh Doan; Vu Tran; Benjamin J. Schwartz

1998-01-01

295

Accuracy of Narrow Band Imaging with Colonoscopy Allows for Distal Non-Cancerous Polyps to Be Left in Place  

MedlinePLUS

... na hyperplastic ( -cancerous po idate NBI crit yp histology. -reviewed sci nd adenomas. e cancer risk. ectal ... objectives were to assess the accuracy of predicting histology (tissue composition or polyp type) by using narrow ...

296

Simultaneous fiber-optic transport and RF phase control of narrow-band millimeter-wave signals using multicontact monolithic semiconductor lasers  

Microsoft Academic Search

We demonstrate fiber-optic transport over 2.2 km of single-mode fiber with continuous RF phase control of narrow-band millimeter-wave signals using a three-section monolithic distributed Bragg reflector (DBR) laser. By injection-locking the laser at the cavity round-trip resonant frequency of 45 GHz, we achieve 360° of continuous, linear RF phase control of the input mm-wave signal by simply varying the bias

Johm B. Georges; Robert A. Lux; Simon P. Yeung; Kam Y. Lau; Wayne Chang

1996-01-01

297

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

298

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

Microsoft Academic Search

Narrow-band imaging (NBI) is an endoscopic technique enhancing mucosal vasculature and better identifying superficial carcinomas\\u000a due to their neo-angiogenic pattern. NBI accuracy is increased by combination with a high-definition television (HDTV) camera.\\u000a The aim of this report was to evaluate the diagnostic improvement of NBI ± HDTV in the evaluation of head and neck squamous\\u000a cell cancer (HNSCC) previously treated by chemo-radiotherapy

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

2010-01-01

299

Composition and temperature-induced effects on the phonon spectra of narrow-band-gap Hg1-xCdxTe  

Microsoft Academic Search

Compositional and temperature-dependent Raman and infrared spectroscopies on the narrow-band-gap II-VI alloy, Hg1-xCdxTe (0<=x<=0.29), are reported in this paper. Raman measurements over this composition range confirm the two-mode behavior of the optical phonons in the alloy, with the frequency positions exhibiting a monotonic change with the alloy composition x. A resonant enhancement of the HgTe-like forbidden longitudinal-optic mode is observed

Shyama Rath; K. P. Jain; S. C. Abbi; C. Julien; M. Balkanski

1995-01-01

300

A narrow-band injection-seeded pulsed titanium:sapphire oscillator-amplifier system with on-line chirp analysis for high-resolution spectroscopy  

Microsoft Academic Search

A narrow-band tunable injection-seeded pulsed titanium:sapphire laser system has been developed for application in high-resolution spectroscopic studies at the fundamental wavelengths in the near infrared as well as in the ultraviolet, deep ultraviolet, and extreme ultraviolet after upconversion. Special focus is on the quantitative assessment of the frequency characteristics of the oscillator-amplifier system on a pulse-to-pulse basis. Frequency offsets between

S. Hannemann; E.-J. van Duijn; W. M. G. Ubachs

2007-01-01

301

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

302

Assessments of Spectral Narrow Band and Weighted-Sum-of-Gray-Gases Models for Computational Fluid Dynamics Simulations of Pool Fires  

Microsoft Academic Search

The statistical narrow band (SNB), correlated-k (CK), and weighted-sum-of-gray-gases (WSGG) models have been incorporated into a computational fluid dynamics (CFD) code. Their accuracy and computing times are evaluated for three pool fires scenarios. CFD_CK and CFD_SNB yield similar predictions, and the former is three times more CPU demanding than the latter. CFD_CK is unrealistic for practical fire applications. Temperature and

S. Dembele; J. Zhang; J. X. Wen

2005-01-01

303

First Results of Exoplanet Observations with the Gran Telescopio Canarias: Narrow-Band Transit Photometry Capable of Detecting Super-Earth-size Planets  

NASA Astrophysics Data System (ADS)

We present the first exoplanet observations from the Gran Telescopio Canarias (GTC) using the OSIRIS tunable filter imager. Our narrow-band transit follow-up observations set a new record for ground-based, narrow-band photometric precision of an exoplanet transit. The demonstrated precision would allow the detection of a transiting super-Earth-sized planet at near-infrared wavelengths. Such high-precision follow-up observations could significantly improve measurements of the size and orbit of transiting super-Earth and Earth-like planets to be discovered by the CoRoT and Kepler space missions (Colon & Ford 2009). OSIRIS is one of two first light instruments for the GTC and features a tunable filter imaging mode. We observed the planet's host star along with several nearby reference stars during each transit, rapidly alternating observations between multiple narrow band-passes. The GTC's large aperture results in small photon noise and minimal scintillation noise, so care must be taken to minimize other potential systematic noise sources. The use of a narrow bandpass (2nm) reduces the effects of differential extinction, and we chose bandpasses that minimize atmospheric absorption and variability. We measure the flux of the target star relative to an ensemble of reference stars, using an aperture photometry algorithm adapted to allow for: 1) the center of the band-pass varying across the field and resulting in sky rings, and 2) a significant defocus to reduce flat fielding uncertainties and increase observing efficiency. We present results from the first tunable filter observations of an exoplanet transit and outline the exciting prospects for future GTC/OSIRIS observations to study super-Earth planets and the atmospheres of giant planets via occultation photometry. Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma.

Ford, Eric B.; Colon, K. D.; Blake, C.; Lee, B.; Mahadevan, S.

2010-01-01

304

Evaluation of the degree of effectiveness of biobeam low level narrow band light on the treatment of skin ulcers and delayed postoperative wound healing.  

PubMed

Twenty-one patients with 31 postoperative delayed open wounds resistant to conventional therapy were randomly allocated to three groups. Group 1 was treated with red low level narrow band (LLNB) light (660 nm); group 2 was treated with infrared LLNB light (940 nm); and group 3 was treated with a placebo such as the Biobeam machine (no light irradiation). Group 1 showed a significant improvement compared to groups 2 and 3 (t-test). PMID:1437861

Iusim, M; Kimchy, J; Pillar, T; Mendes, D G

1992-09-01

305

On the consistent modeling of band-gap narrowing for accurate device-level simulation of scaled SiGe HBTs  

Microsoft Academic Search

We investigate the modeling of heavy-doping induced band-gap narrowing (BGN) in scaled SiGe HBTs featuring high base doping. An inconsistency between simulation results obtained using either Boltzmann or Fermi-Dirac statistics is identified for two widely used commercial device simulators: MEDICI and DESSIS. A new approach to BGN modeling is introduced to correct this problem, and is successfully implemented in DESSIS,

Yun Shi; Guofu Niu; John D. Cressler; David L. Harame

2003-01-01

306

Time-Domain Emission Measurements in K-Band  

NASA Astrophysics Data System (ADS)

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

Hoffmann, Christian; Russer, Peter

2011-08-01

307

Generation condition of the Upper-band and Lower-band chorus emissions in the Earth's magnetosphere  

NASA Astrophysics Data System (ADS)

In the present study, chorus emissions have been analyzed on the basis of the nonlinear growth theory [1] in the Earth's magnetosphere. A rising-tone chorus emission is initially generated continuously in the frequency range from 0.1 to 0.7 fce0, where fce0 is the gyrofrequency in the generation region. Because of the nonlinear damping mechanism [2] the rising-tone chorus is separated into upper and lower bands at half the local gyrofrequency for the quasi-parallel propagation toward higher latitude (i.e. toward larger gyrofrequencies). Thus the lower cutoff of the upper-band chorus indicates half-gyrofrequency at the observational point (1/2 fce), whereas the upper cutoff of the lower-band chorus indicates half the gyrofrequency in the generation region (1/2fce0). We found an observational evidence of such characteristics of upper-band and lower-band chorus observed by the wave form capture (WFC) and the sweep frequency analyzer (SFA) onboard Geotail [3]. Mainly ';'lower-band-only chorus'' (only the lower-band emission exists) is observed and occasionally ';'dual-band chorus'' (both the upper-band and the lower-band emissions) is observed by Geotail. In this study, we statistically analyze the difference between the lower-band-only chorus and the dual-band chorus, using the SFA data obtained during October, 1992 and August, 2011. It has been confirmed that the dual-band chorus is generated because of the nonlinear damping at half the local gyrofrequency during the propagation. When the dual-band chorus propagates toward higher latitudes with its the upper-band part completely damped at half the local gyrofrequencies, the dual-band chorus becomes the lower-band-only chorus. We assume that the upper cutoff frequency of the lower-band chorus equals to the half-gyrofrequency in the generation region. When 0.7 fce0 (i.e. upper limit frequency of the chorus generation) is higher than local 1/2 fce, the dual-band chorus is possibly observed because the higher-frequency part of the upper-band chorus would not be damped. When 0.7 fce0 is lower than local 1/2 fce, the lower-band-only chorus is observed because the upper-band chorus is completely damped. References [1] Omura Y., Y. Katoh and D. Summers (2008), Theory and simulation of the generation of whistler-mode chorus, J. Geophys. Res., 113, A04223, doi:10.1029/2007JA012622. [2] Omura Y., M. Hikishima, Y. Katoh, D.Summers, and S. Yagitani (2009), Nonlinear mechanisms of lower-band and upper-band VLF chorus emissions in the magnetosphere, J. Geophys. Res., 114, A07217, doi:10.1029/2009JA014206 [3] S. Yagitani, T. Habagishi, S. Mori, Y. Omura, and H. Kojima, Generation and propagation characteristics of dual-band chorus emissions observed by Geotail, American Geophysical Union Fall Meeting 2012, December 2012, San Francisco, USA.

Habagishi, T.; Yagitani, S.; Omura, Y.; Kojima, H.

2013-12-01

308

Influence of the surface band structure in photoelectron emission by ultra-short laser pulses  

NASA Astrophysics Data System (ADS)

Photoelectron emission from the valence band of aluminum and beryllium surfaces by ultra-short laser pulses is studied within the Band-Structure-Based - Volkov (BSB-V) approximation, which takes into account the contribution of the band structure of the solid. We found that band structure effects are extremely important for Be(0001), for which signatures of partially occupied surface states can be observed in the electron emission spectra.

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

2014-04-01

309

Spatial distribution of emission in Unidentified Infrared Bands from Midcourse Space Experiment Survey  

Microsoft Academic Search

Recently the Midcourse Space Experiment (MSX) has surveyed the Galactic plane\\u000ain mainly four infrared bands between 6 and 25 micron. Two of these bands cover\\u000aseveral Unidentified Infrared emission Bands (UIBs). With the aim of extracting\\u000athe spatial distribution of the UIB emission on a large scale, a scheme has\\u000abeen developed to model the MSX data with emission

S. K. Ghosh; D. K. Ojha

2002-01-01

310

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

311

Target-specific nanoparticles containing a broad band emissive NIR dye for the sensitive detection and characterization of tumor development.  

PubMed

Current optical probes including engineered nanoparticles (NPs) are constructed from near infrared (NIR)-emissive organic dyes with narrow absorption and emission bands and small Stokes shifts prone to aggregation-induced self-quenching. Here, we present the new asymmetric cyanine Itrybe with broad, almost environment-insensitive absorption and emission bands in the diagnostic window, offering a unique flexibility of the choice of excitation and detection wavelengths compared to common NIR dyes. This strongly emissive dye was spectroscopically studied in different solvents and encapsulated into differently sized (15, 25, 100 nm) amino-modified polystyrene NPs (PSNPs) via a one-step staining procedure. As proof-of-concept for its potential for pre-/clinical imaging applications, Itrybe-loaded NPs were surface-functionalized with polyethylene glycol (PEG) and the tumor-targeting antibody Herceptin and their binding specificity to the tumor-specific biomarker HER2 was systematically assessed. Itrybe-loaded NPs display strong fluorescence signals in vitro and in vivo and Herceptin-conjugated NPs bind specifically to HER2 as demonstrated in immunoassays as well as on tumor cells and sections from mouse tumor xenografts in vitro. This demonstrates that our design strategy exploiting broad band-absorbing and -emitting dyes yields versatile and bright NIR probes with a high potential for e.g. the sensitive detection and characterization of tumor development and progression. PMID:23072943

Behnke, Thomas; Mathejczyk, Julia E; Brehm, Robert; Würth, Christian; Gomes, Fernanda Ramos; Dullin, Christian; Napp, Joanna; Alves, Frauke; Resch-Genger, Ute

2013-01-01

312

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

SciTech Connect

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

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

2012-08-01

313

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

314

CO band emission from MWC 349. I. First overtone bands from a disk or from a wind?  

NASA Astrophysics Data System (ADS)

We have obtained spectra in the K band of the peculiar B[e]-star MWC 349. A 1.85-2.50 mu m spectrum, measured at medium resolution, contains besides the strong IR continuum the first overtone CO bands, the hydrogen recombination lines of the Pfund series, and a number of other neutral atomic lines and ionic lines of low ionization, all in emission. Portions of the CO band and superposed Pfund series lines were observed at resolutions of 10-15 km s-1. The Pfund lines have gaussian profiles with FWHMs of ~ 100 km s-1, are optically thin, and are emitted in LTE. The CO band heads are formed in LTE at temperatures of 3500 to 4000 K. The width of the 2-> 0 band head indicates kinematic broadening of 50 to 60 km s-1. A number of CO emission geometries were investigated by spectral modeling. The emission may occur at the inner edge of the rotating circumstellar disk. In this case, the disk must have an outer bulge which partly blocks the radiation so that the observer sees only a sector on the far side where radial velocities are small. Alternatively, the CO emission originates in a wind and lines have gaussian profiles. Fits to both these geometries are of equally good quality. In a third alternative where the fit is less convincing, the CO emission is optically thin and comes from an extended Keplerian disk. In all successful fits the CO column density is ~ 5* 1020 cm-2.

Kraus, M.; Krügel, E.; Thum, C.; Geballe, T. R.

2000-10-01

315

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

316

Band-gap narrowing in ordered Ga[sub 0. 47]In[sub 0. 53]As  

SciTech Connect

We report the first observation of band-gap energy reduction in Ga[sub 0.47]In[sub 0.53]As deposited on (100) InP by atmospheric pressure organometallic vapor phase epitaxy due to CuPt-type ordering. A reduction of more than 65 meV in the band-gap energy is observed for lattice-matched samples that show strong CuPt-like ordering by transmission electron microscopy. By comparison samples that show no CuPt-like ordering diffraction signatures, do not have reduced band-gap energies. Studies of the influence of growth parameters on the band-gap energy indicate a U-shaped dependence on the growth temperature with a minimum around 550 [degree]C and decreasing band-gap energies with increasing growth rate (at a constant V/III ratio) over the range 0.5--4 [mu]m/h.

Arent, D.J.; Bode, M.; Bertness, K.A.; Kurtz, S.R.; Olson, J.M. (National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401-3393 (United States))

1993-04-12

317

Narrowing and Shifting Emission Line of Dye Laser by Means of Iodine Vapor Attachment.  

National Technical Information Service (NTIS)

The characteristic feature of I2-molecules, namely, the dense spectrum of vibrational-rotational levels in their combining electron states making the mean distance between their emission lines comparable with the width of their Doppler contour, has been e...

V. A. Alekseyev B. A. Konstantinov T. I. Mikhalina B. F. Trinchuk N. G. Ustinov

1986-01-01

318

Molecular nitrogen LBH band system far-UV emissions of sprite streamers  

Microsoft Academic Search

The time dependent optical emission model developed by Liu and Pasko (2004) is applied to studies of far-UV emissions of sprite streamers due to N2 Lyman-Birge-Hopfield (LBH) band system. Modeling results indicate that the LBH emissions of sprite streamers at 70 km are generally stronger by up to a factor of 10 than those from the first negative band system

Ningyu Liu; Victor P. Pasko

2005-01-01

319

Tunneling emission of electrons from semiconductors' valence bands in high electric fields  

SciTech Connect

Tunneling emission currents of electrons from semiconductors to vacuum (needle-shaped GaAs photodetectors) and to a metal (silicon metal-insulator-semiconductor diodes with a tunneling-transparent insulator layer) are studied in high and ultrahigh electric fields. It is shown that, in semiconductors with the n-type conductivity, the major contribution to the emission current is made by the tunneling emission of electrons from the valence band of the semiconductor, rather than from the conduction band.

Kalganov, V. D.; Mileshkina, N. V. [St. Petersburg State University (Petrodvorets Branch), Fock Research Institute of Physics at the (Russian Federation); Ostroumova, E. V. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)], E-mail: elena.ostroumova@mail.ioffe.ru

2006-09-15

320

Transient Increase of the Energy Gap of Superconducting NbN Thin Films Excited by Resonant Narrow-Band Terahertz Pulses  

NASA Astrophysics Data System (ADS)

Observations of radiation-enhanced superconductivity have thus far been limited to a few type-I superconductors (Al, Sn) excited at frequencies between the inelastic scattering rate and the superconducting gap frequency 2?/h. Utilizing intense, narrow-band, picosecond, terahertz pulses, tuned to just below and above 2?/h of a BCS superconductor NbN, we demonstrate that the superconducting gap can be transiently increased also in a type-II dirty-limit superconductor. The effect is particularly pronounced at higher temperatures and is attributed to radiation induced nonthermal electron distribution persisting on a 100 ps time scale.

Beck, M.; Rousseau, I.; Klammer, M.; Leiderer, P.; Mittendorff, M.; Winnerl, S.; Helm, M.; Gol'tsman, G. N.; Demsar, J.

2013-06-01

321

Transient increase of the energy gap of superconducting NbN thin films excited by resonant narrow-band terahertz pulses.  

PubMed

Observations of radiation-enhanced superconductivity have thus far been limited to a few type-I superconductors (Al, Sn) excited at frequencies between the inelastic scattering rate and the superconducting gap frequency 2?/h. Utilizing intense, narrow-band, picosecond, terahertz pulses, tuned to just below and above 2?/h of a BCS superconductor NbN, we demonstrate that the superconducting gap can be transiently increased also in a type-II dirty-limit superconductor. The effect is particularly pronounced at higher temperatures and is attributed to radiation induced nonthermal electron distribution persisting on a 100 ps time scale. PMID:23848912

Beck, M; Rousseau, I; Klammer, M; Leiderer, P; Mittendorff, M; Winnerl, S; Helm, M; Gol'tsman, G N; Demsar, J

2013-06-28

322

Efficient short-wavelength light emission from asymmetric double quantum wells by using electron and hole collection into the same narrow quantum well  

Microsoft Academic Search

We propose an effective method for carrier injection into the high-energy Gamma ground state in a narrow quantum well (QW) in asymmetric double QW systems using Gamma-X-Gamma electron transfer and simultaneous hole tunneling. Although the high-energy state is type-II band-aligned for the electrons, our method enables an efficient injection of both electrons and holes into the same narrow QW, and

Y. Hirose; M. Hosoda; C. Domoto; T. Nishimura; T. Aida

2002-01-01

323

Band gap structure and electron emission property of chemical-vapor-deposited diamond films  

Microsoft Academic Search

The structures of the band gap and defect states of chemical-vapor-deposited diamond films were investigated by photoluminescence spectroscopy, covering wavelength from visible to vacuum ultraviolet (VUV). Band gaps ranging from 5.5 to 3.2 eV were measured for natural, polycrystalline, and amorphous diamond films. Low voltage field emissions were obtained from wide band gap films with band gap states distributed close

J. J Liu; D. Y. T Chiu; D. C Morton; D. H Kang; V. V Zhirnov; J. J Hren; J. J Cuomo

2001-01-01

324

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

325

CONNECTION BETWEEN MID-INFRARED EMISSION PROPERTIES AND NARROW-LINE REGION OUTFLOWS IN TYPE 1 ACTIVE GALACTIC NUCLEI  

SciTech Connect

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 (CF{sub MIR} = L{sub MIR}/L{sub bol}) correlates with the fundamental parameters of AGN accretion process (such as L{sub bol}, black hole mass M{sub BH}, and Eddington ratio L/L{sub Edd}) and the properties of narrow emission lines (as represented by [O III] {lambda}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{sub wing}) correlates more tightly with the continuum luminosity ({lambda}L{sub {lambda}}(5100)) than the luminosity of the line core component (L{sub 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{sub wing}/L{sub bol} rather than with L{sub core}/L{sub bol} or the above fundamental AGN parameters, and the correlation becomes stronger as the infrared wavelength increases. We also confirm the anti-correlations of CF{sub MIR} with L{sub bol} and M{sub BH}, and the lack of dependence of CF{sub MIR} 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 Tinggui; Dong Xiaobo [Key Laboratory for Research in Galaxies and Cosmology, University of Sciences and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Yan Lin, E-mail: zhangkai@shao.ac.cn [Spitzer Science Center, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

2013-05-01

326

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

NASA Technical Reports Server (NTRS)

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

Baines, Kevin H.; West, Robert A.; Giver, Lawrence P.; Moreno, Fernando

1993-01-01

327

The estimation of the electron density ne with a narrow-band photometric system calibrated by model atmospheres.  

NASA Astrophysics Data System (ADS)

A spectrophotometer was originally designed by Barbier (1960) for the study of early-type stars. The band passes were chosen to measure the features of the hydrogen spectrum. To the first definition of the system (Barbier and Morguleff, 1964), two more bands were added, specifically devoted to the peculiar stars of type Ap and Am (Gerbaldi, 1972). The interpretation of these observations has already been given separately. The authors concentrate on the calibration of this spectrophotometric system in terms of Teff, log g and electron density ne.

Gerbaldi, M.; Morguleff, N.

328

Using Lunar Observations to Assess Terra MODIS Thermal Emissive Bands Calibration  

NASA Technical Reports Server (NTRS)

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

Xiong, Xiaoxiong; Chen, Hongda

2010-01-01

329

An intelligent copper(II) luminescent sensor using europium narrow emissions based on titania hybrid material  

NASA Astrophysics Data System (ADS)

A new kind of europium 2,6-Pyridinedicarboxylic acid complex was synthesized and immobilized in titania via modification of this network. Then a europium luminescent hybrid material was fabricated, which gave prominent red emission. More importantly, this target material exhibited highly selective and rapid quenching effect to copper ion in contrast with Ca2+, Na+, K+, Ni2+, Zn2+, Mn2+, Ag+ and Fe3+ in pure water. The europium containing titania hybrid material could be promising for the fabrication of functional sensing devices.

Tang, Ke; Ma, Qianmin; Zhan, Qingguang; Wang, Qianming

2014-07-01

330

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

331

Narrow-band hybrid pulsed laser/EMAT system for noncontact ultrasonic inspection using angled shear waves  

SciTech Connect

Angled, shear wave ultrasonic testing using piezoelectric transducers has been used in industry for years to inspect the plate welds of steel vessels. This method`s reliance on viscous surface couplants limits its reproducibility as well as its applicability for testing surfaces at elevated temperatures. In this work, a pulsed laser/meander line EMAT (electromagnetic acoustic transducer) system was demonstrated to perform testing using vertically polarized, angled, shear waves. This capability was augmented with a narrow-bandwidth laser excitation technique to increase signal-to-noise ratio. The system was tested on both aluminum and steel plates containing saw cuts to mimic cracks. Finally, a steel weld specimen with known defects was tested with good results.

Oursler, D.A.; Wagner, J.W. [Johns Hopkins Univ., Baltimore, MD (United States). Center for Nondestructive Evaluation

1995-05-01

332

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

333

Narrow-band forbidden O III imaging of the QSO 4C 18.68 - A tidal tail revealed?  

NASA Technical Reports Server (NTRS)

The z = 0.313 quasar 4C 18.68 and its surroundings in the light of redshifted forbidden O III were imaged. The QSO appears much more extended than in broad-band images, with a large halo and possibly a faint tidal tail discerned. A broad-band I CCD image taken in 1 - 1.2 arcsec seeing resolves the QSO from a companion galaxy 3.6 arcsec distant, similar to many others seen in the field. It is suggested that the elongated and asymmetric shapes of some QSOs may be due to not-quite-resolved companion galaxies, and that caution be exercised in interpreting luminosity and color profiles as evidence for underlying spiral or elliptical structure.

Shara, M. M.; Moffat, A. F. J.; Albrecht, R.

1985-01-01

334

Hydrogenated amorphous silicon–germanium thin films with a narrow band gap for silicon-based solar cells  

Microsoft Academic Search

Hydrogenated amorphous silicon–germanium (a-SixGe1?x:H) thin films were grown using very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD, 27.13MHz). The films were used in a silicon-based thin film solar cell. The films were grown from a gas mixture of silane (SiH4) and tunable germane (GeH4) gas that was diluted in hydrogen (H2). The results show that the optical band gap

Chao-Chun Wang; Chueh-Yang Liu; Shui-Yang Lien; Ko-Wei Weng; Jung-Jie Huang; Chia-Fu Chen; Dong-Sing Wuu

2011-01-01

335

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

336

Shock Excited SiCI Emission Bands (BX, Transition)  

Microsoft Academic Search

The band system in the region 2700–3100Å, attributed to the B-X transition of the SiCl molecule, has been excited in a hydrogen cum argon shock tube. The enrgy transfer during the shock wave is 4·8 ev which corresponds to a pressure ratio about 380. Seven new bands, 1–1, 2–1, 2–3, 2–4, 2–5, and 3–1 are identified. Molecular constants are obtained

S. K. Kanoo

1981-01-01

337

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

338

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

339

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

SciTech Connect

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

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

2011-07-01

340

Defect-Band Emission Photoluminescence Imaging on Multi-Crystalline Si Solar Cells  

SciTech Connect

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

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

2011-01-01

341

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

342

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

PubMed Central

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

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

2011-01-01

343

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

344

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

PubMed Central

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

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

2013-01-01

345

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

PubMed

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. PMID:23377294

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

346

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

347

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

348

Si3N4 emissivity and the unidentified infrared bands  

NASA Technical Reports Server (NTRS)

Infrared spectroscopy of warm (about 150 to 750 K), dusty astronomical sources has revealed a structured emission spectrum which can be diagnostic of the composition, temperature, and in some cases, even size and shape of the grains giving rise to the observed emission. The identifications of silicate emission in oxygen rich objects and SiC in carbon rich object are two examples of this type of analysis. Cometary spectra at moderate resolution have similarly revealed silicate emission, tying together interstellar and interplanetary dust. However, Goebel has pointed out that some astronomical sources appear to contain a different type of dust which results in a qualitatively different spectral shape in the 8 to 13 micron region. The spectra shown make it appear unlikely that silicon nitride can be identified as the source of the 8 to 13 micron emission in either NGC 6572 or Nova Aql 1982. The similarity between the general wavelength and shape of the 10 micron emission from some silicates and that from the two forms of silicon nitride reported could allow a mix of cosmic grains which include some silicon nitride if only the 8 to 13 micron data are considered.

Russell, Ray W.; Chatelain, M. A.; Hecht, James H.; Stephens, John R.

1989-01-01

349

Photocurrent response wavelength up to 1.1 ?m from photovoltaic cells based on narrow-band-gap conjugated polymer and fullerene derivative  

NASA Astrophysics Data System (ADS)

An extremely narrow-band-gap conjugated polymer poly(5,7-bis(4-decanyl-2-thienyl)thieno[3,4-b]diathiazole-thiophene-2,5) (PDDTT) (Eg~1.01 eV) was synthesized by Stille coupling reaction, which absorbs the light from 330-1220 nm in solid thin film and shows good solution processibility. The polymeric photovoltaic cells based on PDDTT/[6,6]-phenyl-C61-butyric acid methyl ester blend show the short circuit density of 0.83 mA/cm2, open current voltage of 0.35 V, and photocurrent spectra response from 330 to 1100 nm under AM 1.5 simulator (100 mW/cm2).

Xia, Yangjun; Wang, Li; Deng, Xianyu; Li, Dongyun; Zhu, Xuhui; Cao, Yong

2006-08-01

350

Comprehensive Investigation of Areae Gastricae Pattern in Gastric Corpus using Magnifying Narrow Band Imaging Endoscopy in Patients with Chronic Atrophic Fundic Gastritis  

PubMed Central

Background: Barium radiographic studies have suggested the importance of evaluating areae gastricae pattern for the diagnosis of gastritis. Significance of endoscopic appearance of areae gastricae in the diagnosis of chronic atrophic fundic gastritis (CAFG) was investigated by image-enhanced endoscopy. Materials and Methods: Endoscopic images of the corpus lesser curvature were studied in 50 patients with CAFG. Extent of CAFG was evaluated with autofluorescence imaging endoscopy. The areae gastricae pattern was evaluated with 0.2% indigo carmine chromoendoscopy. Micro-mucosal structure was examined with magnifying chromoendoscopy and narrow band imaging. Results: In patients with small extent of CAFG, polygonal areae gastricae separated by a narrow intervening part of areae gastricae was observed, whereas in patients with wide extent of CAFG, the size of the areae gastricae decreased and the width of the intervening part of areae gastricae increased (p < 0.001). Most areae gastricae showed a foveola-type micro-mucosal structure (82.7%), while intervening part of areae gastricae had a groove-type structure (98.0%, p < 0.001). Groove-type mucosa had a higher grade of atrophy (p < 0.001) and intestinal metaplasia (p < 0.001) compared with foveola type. Conclusions: As extent of CAFG widened, multifocal groove-type mucosa that had high-grade atrophy and intestinal metaplasia developed among areae gastricae and increased along the intervening part of areae gastricae. Our observations facilitate our understanding of the development and progression of CAFG.

Kanzaki, Hiromitsu; Uedo, Noriya; Ishihara, Ryu; Nagai, Kengo; Matsui, Fumi; Ohta, Takashi; Hanafusa, Masao; Hanaoka, Noboru; Takeuchi, Yoji; Higashino, Koji; Iishi, Hiroyasu; Tomita, Yasuhiko; Tatsuta, Masaharu; Yamamoto, Kazuhide

2012-01-01

351

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

352

RFID transponders' RF emissions in aircraft communication and navigation radio bands  

Microsoft Academic Search

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

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

2008-01-01

353

Design and properties of intermediate-sized narrow band-gap conjugated molecules relevant to solution-processed organic solar cells.  

PubMed

Increases in the molecular length of narrow band gap conjugated chromophores reveal potentially beneficial optical and electronic properties, thermal stabilities, and high power conversion efficiencies when integrated into optoelectronic devices, such as bulk heterojunction organic solar cells. With the objective of providing useful information for understanding the transition from small-sized molecules to polymers, as well as providing a general chemical design platform for extracting relationships between molecular structure and bulk properties, we set out to vary the electron affinity of the molecular backbone. Therefore, a series of donor (D)-acceptor (A) alternating narrow band gap conjugated chromophores were synthesized based on the general molecular frameworks: D(1)-A(1)-D(2)-A(2)-D(2)-A(1)-D(1) and D(1)-A(1)-D(2)-A(2)-D(2)-A(2)-D(2)-A(1)-D(1). When the central electron-accepting moiety (A(2)) was varied or modified, two classes of molecules could be compared. First, we showed that the alteration of one single electron-accepting group, while maintaining the shape of the molecular framework, can effectively impact the optical properties and energy levels of the molecules. DFT ground state structure optimizations show similar "U" shape conformations among these molecules. Second, we examined how the site-specific introduction of fluorine atom(s) modifies the thermal properties in the solid state, while maintaining relatively similar optical and electrochemical features of interest. Structure-property relationship of such molecular systems could be rationally evaluated in the aspects of thermal-responsive molecular organizations in the solid state and dipole moments both in the ground and excited states. The impact of molecular structure on charge carrier mobilities in field effect transistors and the performance of photovoltaic devices were also studied. PMID:24655075

Liu, Xiaofeng; Sun, Yanming; Hsu, Ben B Y; Lorbach, Andreas; Qi, Li; Heeger, Alan J; Bazan, Guillermo C

2014-04-16

354

Yb5Ga2Sb6: a mixed valent and narrow-band gap material in the RE5M2X6 family.  

PubMed

A new compound Yb5Ga2Sb6 was synthesized by the metal flux technique as well as high frequency induction heating. Yb5Ga2Sb6 crystallizes in the orthorhombic space group Pbam (no. 55), in the Ba5Al2Bi6 structure type, with a unit cell of a = 7.2769(2) Å, b = 22.9102(5) Å, c = 4.3984(14) Å, and Z = 2. Yb5Ga2Sb6 has an anisotropic structure with infinite anionic double chains (Ga2Sb6)(10-) cross-linked by Yb(2+) and Yb(3+) ions. Each single chain is made of corner-sharing GaSb4 tetrahedra. Two such chains are bridged by Sb2 groups to form double chains of 1/? [Ga2Sb6(10-)]. The compound satisfies the classical Zintl-Klemm concept and is a narrow band gap semiconductor with an energy gap of around 0.36 eV calculated from the electrical resistivity data corroborating with the experimental absorption studies in the IR region (0.3 eV). Magnetic measurements suggest Yb atoms in Yb5Ga2Sb6 exist in the mixed valent state. Temperature dependent magnetic susceptibility data follows the Curie-Weiss behavior above 100 K and no magnetic ordering was observed down to 2 K. Experiments are accompanied by all electron full-potential linear augmented plane wave (FP-LAPW) calculations based on density functional theory to calculate the electronic structure and density of states. The calculated band structure shows a weak overlap of valence band and conduction band resulting in a pseudo gap in the density of states revealing semimetallic character. PMID:24224906

Subbarao, Udumula; Sarkar, Sumanta; Gudelli, Vijay Kumar; Kanchana, V; Vaitheeswaran, G; Peter, Sebastian C

2013-12-01

355

Influence of the surface band structure on electron emission spectra from metal surfaces  

NASA Astrophysics Data System (ADS)

Electron distributions produced by grazing impact of fast protons on Mg(0001), Cu(111), Ag(111), and Au(111) surfaces are investigated, focusing on the effects of the electronic band structure. The process is described within the band-structure-based approximation, which is a perturbative method that includes an accurate representation of the electron-surface interaction, incorporating information of the electronic band structure of the solid. For all the studied surfaces, the presence of partially occupied surface electronic states produces noticeable structures in double-differential—energy- and angle-resolved—electron emission probabilities from the valence band. For Mg, Cu, and Ag these structures remain visible in electron emission spectra after adding contributions coming from core electrons, which might make possible their experimental detection, but for Au they are hidden by inner-shell emission.

Archubi, C. D.; Faraggi, M. N.; Silkin, V. M.; Gravielle, M. S.

2014-04-01

356

The Size of the Narrow-line-emitting Region in the Seyfert 1 Galaxy NGC 5548 from Emission-line Variability  

NASA Astrophysics Data System (ADS)

The narrow [O III] ??4959, 5007 emission-line fluxes in the spectrum of the well-studied Seyfert 1 galaxy NGC 5548 are shown to vary with time. From this we show that the narrow-line-emitting region has a radius of only 1-3 pc and is denser (n e ~ 105 cm-3) than previously supposed. The [O III] line width is consistent with virial motions at this radius given previous determinations of the black hole mass. Since the [O III] emission-line flux is usually assumed to be constant and is therefore used to calibrate spectroscopic monitoring data, the variability has ramifications for the long-term secular variations of continuum and emission-line fluxes, though it has no effect on shorter-term reverberation studies. We present corrected optical continuum and broad H? emission-line light curves for the period 1988-2008.

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

2013-12-01

357

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

NASA Astrophysics Data System (ADS)

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)-(1×1):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 in situ ``rehydrogenated'' (111)-(1×1):H diamond surface are characteristically different than emission observed from the as-polished (111)-(1×1):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 in situ hydrogenated (111)-(1×1):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.

1995-10-01

358

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)] [Department of Physics, Washington State University, Pullman, Washington 99164-2814 (United States)

1995-10-15

359

Origin of Multi-band Emission from the Microquasar Cygnus X-1  

NASA Astrophysics Data System (ADS)

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

Zhang, Jianfu; Xu, Bing; Lu, Jufu

2014-06-01

360

Si K-emission bands of hydrogenated SiOx alloys  

NASA Astrophysics Data System (ADS)

X-ray Si K-emission bands of amorphous SiOx: H alloy films (0 <= x <= 1.7) are presented. The samples were prepared by rf glow discharge decomposition of SiH4-CO2-H2 gas mixtures in a capacitive reactor system. For x < 0.5 the Si K-emission bands are very similar in shape and peak position to that of a-Si: H, for 0.5 < x < 1.7, however, a dramatic reshaping of the Si K-emission bands occurs. For x = 1.7 the spectra resemble that of crystalline SiO2 (?-crystobalite). The resulting Si K-emission bands are compared with UPS/XPS spectra of a-SiOx in which, contrary to XES spectra, no impressive changes of spectral features are observed. Our measurements demonstrate that the Si K-emission bands of the system a-SiOx: H are more sensitive to sample composition than UPS/XPS spectra. The results delineate the nontrivial behaviour of Si p-like electrons evolving from covalent Si-Si to rather ionic Si-O bonds.

Wiech, G.; Zahorowski, W.; Baumüller, D.; Šim?nek, A.; Watanabe, H.

1990-06-01

361

CO Cameron band and CO2+ UV doublet emissions in the dayglow of Venus: Role of CO in the Cameron band production  

NASA Astrophysics Data System (ADS)

The present study deals with the model calculations of CO Cameron band and CO2+ ultraviolet doublet emissions in the dayglow of Venus. The overhead and limb intensities of CO Cameron band and CO2+ UV doublet emissions are calculated for low, moderate, and high solar activity conditions. Using updated cross sections, the impact of different e-CO cross sections for Cameron band production is estimated. The electron impact on CO is the major source mechanism of Cameron band, followed by electron and photon impact dissociation of CO2. The overhead intensities of CO Cameron band and CO2+UV doublet emissions are about a factor of 2 higher in solar maximum than those in solar minimum condition. The effect of solar EUV flux models on the emission intensity is ˜30-40% in solar minimum condition and ˜2-10% in solar maximum condition. At the altitude of emission peak (˜135 km), the model predicted limb intensity of CO Cameron band and CO2+ UV doublet emissions in moderate (F10.7=130) solar activity condition is about 2400 and 300 kR, respectively, which is in agreement with the very recently published SPICAV/Venus Express observation. The model limb intensity profiles of CO Cameron band and CO2+UV doublet are compared with SPICAV observation. We also calculated intensities of N2Vegard-Kaplan UV bands and O I 2972 Å emissions during moderate and high solar activity conditions.

Bhardwaj, Anil; Jain, Sonal Kumar

2013-06-01

362

Model for the production of CO Cameron band emission in Comet 1P/Halley  

NASA Astrophysics Data System (ADS)

The abundance of CO2 in comets has been derived using CO Cameron band (a3??X1?+) emission assuming that photodissociative excitation of CO2 is the main production process of CO(a3?). On comet 1P/Halley the Cameron (1-0) band has been observed by International Ultraviolet Explorer (IUE) on several days in March 1986. A coupled chemistry-emission model is developed for comet 1P/Halley to assess the importance of various production and loss mechanisms of CO(a3?) and to calculate the intensity of Cameron band emission on different days of IUE observation. Two different solar EUV flux models, EUVAC of Richards et al. (1994) and SOLAR2000 of Tobiska (2004), and different relative abundances of CO and CO2, are used to evaluate the role of photon and photoelectron in producing CO molecule in a3? state in the cometary coma. It is found that in comet 1P/Halley 60-70% of the total intensity of the Cameron band emission is contributed by electron impact excitation of CO and CO2, while the contribution from photodissociative excitation of CO2 is small (20-30%). Thus, in the comets where CO and CO2 relative abundances are comparable, the Cameron band emission is largely governed by electron impact excitation of CO, and not by the photodissociative excitation of CO2 as assumed earlier. Model calculated Cameron band 1-0 emission intensity (40 R) is consistent with the observed IUE slit-averaged brightness (37±6 R) using EUVAC model solar flux on 13 March 1986, and also on other days of observations. Since electron impact excitation is the major production mechanism, the Cameron emission can be used to derive photoelectron density in the inner coma rather than the CO2 abundance.

Raghuram, Susarla; Bhardwaj, Anil

2012-04-01

363

Broad-band emission from chromium doped germanium garnets  

Microsoft Academic Search

By varying the composition of a series of germanium garnets, it is possible to change the lattice constant of the structure over a wide range, and thus the crystal field. Three Cr-doped germanium garnets (Ca3Al2Ge3O12, CaY2Mg2Ge3O12, and MgY2Mg2Ge3O12) have been grown as single crystals. Spectroscopic results show that in these garnets the broadband emission at room temperature is so strong

H. P. Christensen; H. P. Jenssen

1982-01-01

364

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

365

Synthetic rotational profiles of emission and absorption bands of interstellar polycyclic aromatic hydrocarbons  

Microsoft Academic Search

The spectrometers on board Herschel are likely to be able to detect far-IR emission bands from interstellar PAHs, possibly resolving their rotational envelopes. For some specific PAHs we calculated synthetic rotational profiles of their low-energy vibrational modes and of their low-lying permitted electronic transitions, for comparison respectively with the forthcoming Herschel observations and high resolution spectra of Diffuse Interstellar Bands.

G. Malloci; G. Mulas; C. Joblin; D. Toublanc; I. Porceddu

2005-01-01

366

An atlas of synthetic absorption and emission bands of interstellar PAHs  

Microsoft Academic Search

In the framework of the interstellar PAHs hypothesis, absorption bands in the vis\\/UV and far-IR skeletal emission bands are expected to be a fingerprint of specific species in this class. We developed a detailed Monte-Carlo model of the photophysics of isolated interstellar PAHs which provides a powerful tool for single-molecule identification. We present synthetic spectra predicted by the above general

G. Malloci; G. Mulas; C. Joblin; I. Porceddu

2005-01-01

367

Calculation of Band-Structure Effects in Field-Emission Tunneling from Tungsten  

Microsoft Academic Search

A calculation was made to determine whether band-structure effects in field emission, as described in the Stratton theory of tunneling from a metal, could explain the anomalous total energy distribution (TED) for the directions of tungsten obtained by Swanson and Crouser. In applying the Stratton theory, a simple model for the tungsten energy bands based on Loucks's calculated relativistic augmented-plane-wave

Douglas Nagy; P. H. Cutler

1969-01-01

368

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

369

Band structure of ZnO from resonant x-ray emission spectroscopy  

Microsoft Academic Search

Soft x-ray emission and absorption spectroscopy of the OK -edge are employed to investigate the electronic structure of wurtzite ZnO(0001). A quasiparticle band structure calculated within the GW approximation agrees well with the data, most notably with the energetic location of the Zn3d-O2p hybridized state and the anisotropy of the absorption spectra. Dispersion in the band structure is mapped using

A. R. H. Preston; B. J. Ruck; L. F. J. Piper; A. Demasi; K. E. Smith; A. Schleife; F. Fuchs; F. Bechstedt; J. Chai; S. M. Durbin

2008-01-01

370

Single-photon emission in telecommunication band from an InAs quantum dot grown on InP with molecular-beam epitaxy  

NASA Astrophysics Data System (ADS)

We report on the experimental demonstration of a single-photon source based on an InAs quantum dot (QD) on InP grown by molecular-beam epitaxy emitting in the telecommunication band. We develop a method to reduce the QD density to prevent inter-dot coupling via tunneling through coupled excited states. A single InAs QD embedded in an as-etched pillar structure exhibits intense and narrow emission lines. Photon antibunching is clearly observed using superconducting single-photon detectors with high sensitivity, and further improvement of the generated single-photon purity is demonstrated with below-barrier-bandgap excitation.

Liu, X.; Akahane, K.; Jahan, N. A.; Kobayashi, N.; Sasaki, M.; Kumano, H.; Suemune, I.

2013-08-01

371

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

372

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

373

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

NASA Astrophysics Data System (ADS)

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

Nötzold, D.

1997-09-01

374

Narrow band imaging with magnification for dysplasia detection and pit pattern assessment in ulcerative colitis surveillance: a case with multiple dysplasia associated lesions or masses  

PubMed Central

A 62 year old man with longstanding ulcerative colitis and previous endoscopic excision of two dysplasia associated lesions or masses (DALMs) was admitted to our endoscopy unit for evaluation and resection of other possible DALMs. He had previously been offered and refused colectomy because of comorbidity from Parkinson's disease. He had multiple polypoid and sessile lesions which were assessed using a third generation prototype narrow band imaging (NBI) colonoscope with magnification. Selected lesions were either biopsied or resected with a combination of endoscopic submucosal dissection and endoscopic mucosal resection techniques. We correlated the pit pattern and vascular pattern intensity seen with magnification NBI with histology of both inflammatory and dysplastic lesions. Dysplastic areas showed Kudo pit patterns II, IIIL, and IV and high vascular pattern intensity. Non?dysplastic and dysplastic areas of recurrence immediately adjacent to the scar from a previous endoscopic mucosal resection site were also assessed. This is the first case report where NBI has been shown to help in DALM detection and to distinguish dysplastic from non?dysplastic mucosa in ulcerative colitis.

East, J E; Suzuki, N; von Herbay, A; Saunders, B P

2006-01-01

375

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

2013-01-01

376

Effect of Narrow Band Ultraviolet B Therapy versus Methotrexate on Serum Levels of Interleukin-17 and Interleukin-23 in Egyptian Patients with Severe Psoriasis  

PubMed Central

Background. There is raised interest in the involvement of interleukin-(IL-)23/T-helper 17 cells (Th17) axis in the pathogenesis of psoriasis. Objectives. To compare the effect of narrow band ultraviolet B (NB-UVB) and methotrexate (MTX) therapy on serum levels of IL-17 and IL-23 in psoriatic patients. Methods. Thirty patients with severe plaque psoriasis were included: 15 patients received NB-UVB three times weekly (group I) and 15 patients received MTX 0.3?mg/kg per week (group II), both for 8 weeks. Before and after treatment, serum levels of IL-17 and IL-23 were investigated by ELISA technique and psoriasis area and severity index (PASI) was calculated. Results. After treatment, all patients showed a reduction in their PASI score, IL-17 and IL-23 serum levels with a nonsignificant difference between both therapeutic modalities (P value >0.05). A positive correlation was detected between the percent of reduction of IL-17, IL-23 and the percent of reduction of PASI score for patients receiving both treatments. No correlation was found between the percent of reduction of IL-17, IL-23 and duration of disease or age of all patients in this study. Conclusion. Interleukin-17 and IL-23 serum level may serve as a potential biomarker for predicting the prognosis and therapeutic response of NB-UVB or MTX in treating psoriasis.

Elghandour, Tarek Mahmoud; Youssef, Sahar El Sayed; Aly, Dalia Gamal; Abd Elhameed, Mohamed Said; Abdel Moneim, Mehrevan Mostafa

2013-01-01

377

Evaluation of the Efficacy of Topical Tetracycline in Enhancing the Effect of Narrow Band UVB against Vitiligo: A Double-Blind, Randomized, Placebo-Controlled Clinical Trial.  

PubMed

Background. Vitiligo is a pigmentary disorder characterized by depigmented macules due to absence of melanocytes. Increased levels of tumor necrosis factor alpha and interleukin-1 in the epidermis of lesions may play a role in keratinocyte apoptosis and less production of melanogenic cytokines. Tetracyclines reduce production of tumor necrosis factor alpha and interleukin-1. Objective. To evaluate the effect of topical tetracycline on vitiligo patients on phototherapy. Methods. Thirty cases of generalized stable vitiligo were chosen randomly and pigmentation of two assigned lesions on right and left sides (same size and location) was determined by vitiligo area severity index, and medication and placebo were randomly assigned to be applied twice daily on either right or left side, respectively. Images were taken of the lesions at the end of the 4th, 8th, and 12th weeks and pigmentations were compared to baseline using aforementioned index. The patients also took narrow band ultraviolet B two to three times a week. Results. Mean pigmentation, based on vitiligo area severity index, changed significantly from 90.1667 to 86.6667 (P = 0.026) and on placebo side from 89.6667 to 86.8333 (P = 0.026). There was no significant difference between medication and placebo sides in terms of pigmentation (P = 0.566). Conclusions. No significant difference in improving repigmentation between medication and placebo sides was seen. PMID:24665368

Kalafi, Amir; Jowkar, Farideh

2014-01-01

378

Coherent Emission from Ho(3+) Ions by Pumping into the YIG Absorption Band.  

National Technical Information Service (NTIS)

Coherent emission from Ho(3+) ions (2.1 micrometer) in a YIG host at 77 K has been observed by optical pumping into the electronic absorption bands of the YIG host material, using (i) a pulsed Nd: glass laser to pump into the tail of the 6A(1g) to 4T(1g) ...

R. G. Stafford H. Masui R. L. Farrow R. K. Chang L. G. van Uitert

1976-01-01

379

Rare gas—oxygen emission bands and rare gas continua in the UV and VUV  

Microsoft Academic Search

E-beam excitation of rare gas and rare gas—oxygen and\\/or N2O mixtures has revealed various prominent emission features. In the case of Ar\\/O2, new emission bands at 185.0 and 204.5 nm have been recorded. Excitation of Kr\\/O2 and Kr\\/N2O mixtures leads to a broad continuum and several undulations in the UV. Emission features in XeO have been briefly reexamined. Although no

D. E. Johnson

1995-01-01

380

Narrow bandpass layered synthetic microstructure-based pinhole camera to image a tokamak plasma in H-like carbon emission at 34 A  

SciTech Connect

The layered synthetic microstructure (LSM) technology has made two-dimensional soft x-ray imaging of a tokamak plasma in a single impurity spectral line emission feasible. The curved LSM is used both as an optical filter, with a bandpass in the range of interest on the order of 1.5 A, and as a focusing optic. A detailed design of a narrow bandpass curved LSM-based pinhole camera, which will image the the region from the scrape-off layer 26 cm into the plasma in the DIII-D tokamak plasma in C VI Lyman {alpha} emission at 34 A, will be presented.

Regan, S.P.; Huang, L.K.; Finkenthal, M.; Moos, H.W. (The Johns Hopkins University, Baltimore, Maryland 21218 (United States))

1992-10-01

381

Interpreting Methanol v2-band Emission in Comets using Empirical Fluorescence g-factors  

NASA Astrophysics Data System (ADS)

The present study concentrates on the spectral region from ~ 2970 - 3010 cm-1 (3.367 - 3.322 ?m), which is dominated by emission in the ?7 band of C2H6 and the ?2 band of CH3OH, with minor contributions from CH3OH (?9 band), CH4 (?3), and OH prompt emissions (?1 and ?2 - ?1). Based on laboratory jetcooled spectra (at a rotational temperature near 20 K)[1], we incorporated approximately 100 lines of the CH3OH ?2 band, having known frequencies and lower state rotational energies, into our model. Line intensities were determined through comparison with several comets we observed with NIRSPEC at Keck 2, after removal of continuum and additional molecular emissions and correcting for atmospheric extinction. In addition to the above spectral region, NIRSPEC allows simultaneous sampling of the CH3OH ?3 band (centered at 2844 cm-1, or 3.516 ?m) and several hot bands of H2O in the ~ 2.85 - 2.9 ?m region, at a nominal spectral resolving power of ~ 25,000 [2]. Empirical g-factors for ?2 lines were based on the production rate as determined from the ?3 Q-branch intensity; application to comets spanning a range of rotational temperatures (~ 50 - 90 K) will be reported. This work represents an extension of that presented for comet 21P/Giacobini-Zinner at the 2010 Division for Planetary Sciences meeting [3]. Our empirical study also allows for quantifying CH3OH in comets using IR spectrometers for which the ?3 and ?2 bands are not sampled simultaneously, for example CSHELL / NASA-IRTF or CRIRES / VLT.

Disanti, M. A.; Villanueva, G. L.; Bonev, B. P.; Mumma, M. J.; Paganini, L.; Gibb, E. L.; Magee-Sauer, K.

2011-10-01

382

High-resolution spectroscopy of emission bands of PAHs and nanodiamonds in extended objects  

NASA Astrophysics Data System (ADS)

The UIR bands are found in a wide variety of sources e.g. H II regions, PNe, post-AGB stars, YSOs, the diffuse ISM, external galaxies and active galactic nuclei and are normally attributed to polycyclic aromatic hydrocarbons (PAHs). Apart from the intrinsic importance in determining the chemical form of interstellar matter and its role in astrophysical processes, there are much wider astronomical implications; e.g. the use of the UIR features as a probe of external galaxies. A few objects have recently been shown to exhibit IR emission from nanodiamonds. A high-resolution study has been undertaken of near-infrared emission (3.0 - 3.6 µm) from a variety of objects (Elias 1, the Orion Bar and the CS region of HD 44179), and additionally of the 11.3 µm emission feature in the Red Rectangle nebula. The aim has been to investigate the spatial intensity variations of the bands within these objects and to map the evolution of their spectral profiles. This provides insight into the nature of the carriers and is a probe of the physical and chemical properties of the circumstellar and nebular environments. Elias 1 is an interesting case as it exhibits the rare nanodiamond emission at 3.4/3.5 µm in addition to 3.3 µm PAH emission which is found to be more extended. The Red Rectangle is also unusual in that the UIR emission is very strong in the carbon-rich nebula whereas the silicate emission appears to be confined largely to the circumbinary disk. This chemical spatial separation must reflect different epochs of mass-loss. The 11.3 µm emission feature develops substructure as a function of offset in a manner analogous to the development of the 3.3 µm band. Spectra were obtained at UKIRT, using the UIST (near-IR, R = 700) and MICHELLE (mid-IR, R = 1000) instruments.

Topalovic, Radmila; McCombie, June; Kerr, Tom H.; Russell, Julian; Sarre, Peter J.

383

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

384

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

385

Characteristics of banded chorus-like emission measured by the TC-1 Double Star spacecraft  

NASA Astrophysics Data System (ADS)

We present a study of the spatio-temporal characteristics of banded whistler-mode emissions. It covers the full operational period of the TC-1 spacecraft, between January 2004 and the end of September 2007. The analyzed data set has been visually selected from the onboard-analyzed time-frequency spectrograms of magnetic field fluctuations below 4 kHz measured by the STAFF/DWP wave instrument situated onboard the TC-1 spacecraft with a low inclination elliptical equatorial orbit. This orbit covers magnetic latitudes between -39o and 39o. The entire data set has been collected between L=2 and L=12. Our results show that almost all intense emissions (above a threshold of 10-5nT2Hz-1) occur at L-shells from 6 to 12 and in the MLT sector from 2 to 11 hours. This is in a good agreement with previous observations. We determine the bandwidth of the observed emission by an automatic procedure based on the measured spectra. This allows us to reliably calculate the integral amplitudes of the measured signals. The majority of the largest amplitudes of chorus-like emissions were found closer to the Earth. The other result is that the upper band chorus-like emissions (above one half of the electron cyclotron frequency) are much less intense than the lower band chorus-like emissions (below one half of the electron cyclotron frequency) and are usually observed closer to the Earth than the lower band. This work has received EU support through the FP7-Space grant agreement n 284520 for the MAARBLE collaborative research project.

Macúšová, Eva; Santolík, Ond?ej; Cornilleau-Wehrlin, Nicole; Yearby, Keith

2013-04-01

386

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

NASA Astrophysics Data System (ADS)

In the 2500-8500 cm-1 region several strong emission bands of 40ArH were observed by Fourier transform spectroscopy through a dc glow discharge in a mixture of argon and hydrogen. Rotational-electronic transitions of the two previously unstudied 4p-5s and 5p-6s,v=0-0, bands of 40ArH were measured and assigned in the 6060 and 3770 cm-1 regions, respectively. A simultaneous fit of the emission transitions of the 4p-5s and 5p-6s bands and an extended set of transitions of the 6s-4p band observed by Dabrowski, Tokaryk, and Watson [J. Mol. Spectrosc. 189, 95 (1998)] and remeasured in the present work yielded consistent values of the spectroscopic parameters of the electronic states under investigation. In the branch of the 4p-5s band with transitions of type QQf3e we observed a narrowing in the linewidths with increasing rotational quantum number N. The rotational dependence of the linewidth is caused by predissociation of the 5s state by the repulsive ground 4s state through homogeneous coupling and changes in overlap integrals of the vibrational wave functions with the rotational level. Analysis was based on the Fermi's golden rule approximation model. In the 4p-5s band region a vibrational sequence ofv'-v''=1-1, 2-2, and 3-3 were recorded and a number of transitions belonging to the strongest QQf3e form branch of the 1-1 band were analyzed.

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

2005-03-01

387

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

388

2D XANES-XEOL mapping: observation of enhanced band gap emission from ZnO nanowire arrays.  

PubMed

Using 2D XANES-XEOL spectroscopy, it is found that the band gap emission of ZnO nanowire arrays is substantially enhanced i.e. that the intensity ratio between the band gap and defect emissions increases by more than an order of magnitude when the excitation energy is scanned across the O K-edge. Possible mechanisms are discussed. PMID:24845079

Wang, Zhiqiang; Guo, Xiaoxuan; Sham, Tsun-Kong

2014-06-21

389

Off-axis continuous-wave cavity-enhanced absorption spectroscopy of narrow-band and broadband absorbers using red diode lasers  

NASA Astrophysics Data System (ADS)

We present an application of continuous-wave (cw) cavity-enhanced absorption spectroscopy (CEAS) with off-axis alignment geometry of the cavity and with time integration of the cavity output intensity for detection of narrow-band and broadband absorbers using single-mode red diode lasers at ?=687.1 nm and ?=662 nm, respectively. Off-axis cw CEAS was applied to kinetic studies of the nitrate radical using a broadband absorption line at ?=662 nm. A rate constant for the reaction between the nitrate radical and E-but-2-eneof (3.78+/-0.17)×10-13 cm3molecule-1s-1 was measured using a discharge-flow system. A nitrate-radical noise-equivalent (1?? root-mean-square variation of the signal) detection sensitivity of 5.5×109 moleculecm-3 was achieved in a flow tube with a diameter of 4 cm and for a mirror reflectivity of 99.9% and a lock-in amplifier time constant of 3 s. In this case, a noise-equivalent fractional absorption per one optical pass of 1.6×10-6 was demonstrated at a detection bandwidth of 1 Hz. A wavelength-modulation technique (modulation frequency of 10 kHz) in conjunction with off-axis cw CEAS has also been used for recording 1f- and 2f-harmonic spectra of the RR(15) absorption of the b1?g+-X3?g- (1,0) band of molecular oxygen at /line{? }=14553.947 cm-1. Noise-equivalent fractional absorptions per one optical pass of 1.35×10-5, 6.9×10-7 and 1.9×10-6 were obtained for direct detection of the time-integrated cavity output intensity, 1f- and 2f-harmonic detection, respectively, with a mirror reflectivity of 99.8%, a cavity length of 0.22 m and a detection bandwidth of 1 Hz.

Kasyutich, V. L.; Canosa-Mas, C. E.; Pfrang, C.; Vaughan, S.; Wayne, R. P.

390

Usefulness of Non-Magnifying Narrow-Band Imaging in Screening of Early Esophageal Squamous Cell Carcinoma: A Prospective Comparative Study Using Propensity Score Matching  

PubMed Central

OBJECTIVES: The usefulness of non-magnifying endoscopy with narrow-band imaging (NBI; NM-NBI) in the screening of early esophageal squamous cell carcinoma (SCC) and high-grade intraepithelial neoplasia (HGIN) remains unclear. Here, we aimed to compare NM-NBI and chromoendoscopy with iodine staining (CE-Iodine) in terms of the diagnostic performance, and to evaluate the usefulness of NM-NBI in detecting early esophageal SCC. METHODS: We prospectively enrolled 202 consecutive patients (male/female=180/22; median age, 67 years) with high-risk factors for esophageal SCC. All patients received endoscopic examination with NM-NBI and CE-Iodine to screen for early esophageal SCC or HGIN. We conducted the examinations sequentially, and calculated the accuracy, sensitivity, and specificity through a per-lesion-based analysis. A propensity score matching analysis was performed to reduce the effects of selection bias, and we compared the respective outcomes according to NM-NBI and CE-Iodine after matching. RESULTS: The accuracy, sensitivity, and specificity of NM-NBI were 77.0, 88.3, and 75.2%, respectively, and those for unstained areas by CE-Iodine were 68.0, 94.2, and 64.0, respectively. The accuracy and specificity of NM-NBI were superior to those of CE-Iodine (P=0.03 and P=0.01, respectively). However, the sensitivity did not significantly differ between NM-NBI and CE-Iodine (P=0.67). The accuracy and specificity of NM-NBI before matching were superior to those of CE-Iodine after matching (P=0.04 and P=0.03). CONCLUSIONS: NM-NBI was useful and reliable for the diagnosis of esophageal SCC and can be a promising screening strategy for early esophageal SCC.

Nagami, Yasuaki; Tominaga, Kazunari; Machida, Hirohisa; Nakatani, Masami; Kameda, Natsuhiko; Sugimori, Satoshi; Okazaki, Hirotoshi; Tanigawa, Tetsuya; Yamagami, Hirokazu; Kubo, Naoshi; Shiba, Masatsugu; Watanabe, Kenji; Watanabe, Toshio; Iguchi, Hiroyoshi; Fujiwara, Yasuhiro; Ohira, Masaichi; Hirakawa, Kosei; Arakawa, Tetsuo

2014-01-01

391

An educational intervention to improve the endoscopist's ability to correctly diagnose small gastric lesions using magnifying endoscopy with narrow-band imaging  

PubMed Central

Background Magnifying endoscopy with narrow-band imaging (ME-NBI) and a simple and systematic classification system based on microvascular and microsurface patterns, the “VS” classification system (VSCS), have been shown to be useful for the diagnosis of early gastric cancer. The aim of this study was to clarify whether an educational lecture about the VSCS improves performance with ME-NBI. Methods Sixty-four gastrointestinal endoscopists took the 1st exam before receiving the lecture about the VSCS, the 2nd exam immediately after the lecture, and the 3rd exam 2 months after the lecture. We compared the VSCS-based diagnostic accuracy among the participants before and after the lecture. Results The proportion of correct diagnoses was significantly higher, at 70.8% in the 2nd exam than in the 1st exam, at 53.1% (P<0.001). The correct diagnosis rate in the 3rd exam was significantly lower than that in the 2nd exam (60.9% vs. 70.8%; P<0.001) but was still higher than that in the 1st exam (60.9% vs. 53.1%; P<0.001). The difference in proportion of correct diagnosis between the 2nd and the 3rd exams was smaller among routine ME-NBI practitioners (n=6; 79.2% and 76.1%, respectively), compared to that among non-routine practitioners (n=34; 71.6% and 59.8%, respectively) or non-practitioners (n=24; 67.5% and 58.8%, respectively). Conclusion This study revealed that an educational intervention increased correct diagnosis rate of small gastric lesions using the VSCS, diagnosis criteria based on ME-NBI and also showed that the routine use of the modality and the diagnosis criteria was necessary to maintain diagnostic skills.

Mabe, Katsuhiro; Yao, Kenshi; Nojima, Masanori; Tanuma, Tokuma; Kato, Mototsugu

2014-01-01

392

Efficacy of capillary pattern type IIIA/IIIB by magnifying narrow band imaging for estimating depth of invasion of early colorectal neoplasms  

PubMed Central

Background Capillary patterns (CP) observed by magnifying Narrow Band Imaging (NBI) are useful for differentiating non-adenomatous from adenomatous colorectal polyps. However, there are few studies concerning the effectiveness of magnifying NBI for determining the depth of invasion in early colorectal neoplasms. We aimed to determine whether CP type IIIA/IIIB identified by magnifying NBI is effective for estimating the depth of invasion in early colorectal neoplasms. Methods A series of 127 consecutive patients with 130 colorectal lesions were evaluated from October 2005 to October 2007 at the National Cancer Center Hospital East, Chiba, Japan. Lesions were classified as CP type IIIA or type IIIB according to the NBI CP classification. Lesions were histopathologically evaluated. Inter and intraobserver variabilities were assessed by three colonoscopists experienced in NBI. Results There were 15 adenomas, 66 intramucosal cancers (pM) and 49 submucosal cancers (pSM): 16 pSM superficial (pSM1) and 33 pSM deep cancers (pSM2-3). Among lesions diagnosed as CP IIIA 86 out of 91 (94.5%) were adenomas, pM-ca, or pSM1; among lesions diagnosed as CP IIIB 28 out of 39 (72%) were pSM2-3. Sensitivity, specificity and diagnostic accuracy of the CP type III for differentiating pM-ca or pSM1 (<1000 ?m) from pSM2-3 (?1000 ?m) were 84.8%, 88.7 % and 87.7%, respectively. Interobserver variability: ? = 0.68, 0.67, 0.72. Intraobserver agreement: ? = 0.79, 0.76, 0.75 Conclusion Identification of CP type IIIA/IIIB by magnifying NBI is useful for estimating the depth of invasion of early colorectal neoplasms.

2010-01-01

393

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

394

Optical Spectroscopy of IRAS Sources with Infrared Emission Bands. 1: IRAS 21282+5050 and the Diffuse Interstellar Bands. Semiannual Status Report May 31, 1987-November 30, 1987.  

National Technical Information Service (NTIS)

Spectroscopy of the starlike optical counterpart to IRAS 21282+5050, a source with the hydrocarbon infrared emission band spectrum, shows an 07(f)-(WC11) planetary nebula nucleus suffering an extinction of 5.7 mag. Emission line widths in the WC spectrum ...

M. Cohen B. F. Jones

1987-01-01

395

Modeled and observed N2 Lyman-Birge-Hopfield band emissions: A comparison  

NASA Astrophysics Data System (ADS)

A thorough understanding of how the N2 Lyman-Birge-Hopfield (LBH) band emissions vary with altitude is essential to the use of this emission by space-based remote sensors. In this paper, model-to-model comparisons are first performed to elucidate the influence of the solar irradiance spectrum, intrasystem cascade excitation, and O2 photoabsorption on the limb profile. Next, the observed LBH emissions measured by the High resolution Ionospheric and Thermospheric Spectrograph aboard the Advanced Research and Global Observation Satellite are compared with modeled LBH limb profiles to determine which combination of parameters provides the best agreement. The analysis concentrates on the altitude dependence of the LBH (1,1) band, the brightest LBH emission in the observations. In the analysis, satellite drag data are used to constrain the neutral densities used for the data-to-model comparisons. For the average limb profiles on two of the three days analyzed (28, 29, and 30 July 2001), calculations using direct excitation alone give slightly better agreement with the observations than did calculations with cascading between the singlet electronic N2 states (a1?g, a??-u, and w1?u) however, the differences between the observed profiles and either model are possibly greater than the differences between the models. Nevertheless, both models give excellent agreement with the observations, indicating that current models provide an adequate description of the altitude variation of the N2 LBH (1,1) band emissions. Consequently, when using the LBH bands to remotely sense thermospheric temperatures, which can be used to provide an unprecedented view of the thermosphere, the temperatures derived have a negligible dependence on the model used.

Eastes, R. W.; Murray, D. J.; Aksnes, A.; Budzien, S. A.; Daniell, R. E.; Krywonos, A.

2011-12-01

396

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

SciTech Connect

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

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

2013-06-10

397

The Investigation of the Thermoluminescence Emission Bands of LiF:Mg,Ti (TLD-100) by a Simple Developed Model  

NASA Astrophysics Data System (ADS)

In this study, a new simple model based on the classical treatment of lattice vibrations and the Franck-Condon principle is developed to describe the shape of thermoluminescence (TL) emission bands of crystalline solids. According to developed model, shape of the emission band has a Gaussian form and depends on just two physical parameters: peak energy E0 and broadening of emission spectra U. In order to demonstrate the success of the developed model, the emission spectra of dosimetric material LiF:Mg,Ti (TLD-100) was also measured. Then, a computerised best-fit program including the developed model was used to analyse the emission spectra. The number of individual bands and their kinetic parameters were also obtained by this program. Two emission bands were observed for all glow peaks with peak energies at around 3.0 eV and 2.75 eV.

Yazici, A. Necmeddýn; Öztürk, Z.; Bedýr, M.

2001-07-01

398

Generation and Propagation Characteristics of Dual-Band Chorus Emissions Observed by Geotail  

NASA Astrophysics Data System (ADS)

We analyze the generation and propagation characteristics of chorus emissions observed by the wave form capture (WFC) and the sweep frequency analyzer (SFA) onboard the Geotail spacecraft in the dayside outer magnetosphere (L from 9 to 10). We examine any observational evidence, which may validate the nonlinear growth theory of the chorus emissions [1]. In the nonlinear growth theory a rising-tone element is initially generated continuously in the frequency range from 0.1 to 0.7 fce, where fce is the gyrofrequency in the generation region. Because of the nonlinear damping mechanism the rising-tone element is separated into upper and lower bands at half the local gyrofrequency (1/2 fce) through propagation [2]. As the rising-tone emissions are generated in the minimum-B region and propagate toward the larger-B regions along the geomagnetic field line, the upper cutoff of the lower-band chorus corresponds to 1/2 fce in the generation region, and the lower cutoff of the upper-band chorus corresponds to 1/2 fce at the observation point. In this study, we analyze the SFA spectrum data (consecutively over several hours) and WFC waveform data (several seconds) of the dual-band chorus emissions observed by Geotail. As a result, it is found that the upper cutoff of the lower-band chorus coincides with 1/2 fce at the minimum-B region estimated from the geomagnetic field line connecting to the Geotail position by using the Tsyganenko geomagnetic field model (TS04 model), whereas the lower cutoff of the upper-band chorus coincides with 1/2 fce locally at the observation point. We also examine the amplitude of a rising-tone emission using the WFC waveform data on the basis of the nonlinear growth theory. The amplitude at the generation region is estimated from the observed frequency sweep rate of the emission, and the nonlinear growth of the amplitude through propagation toward the observation point is calculated from the nonlinear growth rate, which is found consistent with the observed amplitude. We will also discuss the observational evidence for the threshold amplitudes and the optimum amplitudes required for triggering rising-tone chorus emissions in the generation region. [1] Omura Y., Y. Katoh and D. Summers (2008), Theory and simulation of the generation of whistler-mode chorus, J. Geophys. Res., 113, A04223, doi:10.1029/2007JA012622. [2] Omura Y., M. Hikishima, Y. Katoh, D. Summers, and S. Yagitani (2009), Nonlinear mechanisms of lower-band and upper-band VLF chorus emissions in the magnetosphere, J.Geophys. Res., 114, A07217, doi:10.1029/2009JA014206. [3] Omura Y., and D. Nunn (2011), Triggering process of whistler mode chorus emissions in the magnetosphere, J. Geophys. Res., 116, A05205, doi:10.1029/2010JA016280.

Yagitani, S.; Habagishi, T.; Mori, S.; Omura, Y.; Kojima, H.

2012-12-01

399

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

400

The influence of deformation bands upon fluid flow using profile permeametry and positron emission tomography  

NASA Astrophysics Data System (ADS)

Cataclastic deformation bands are significant discontinuities in sandstone reservoirs since they have dramatically reduced porosity and permeability relative to their host rock, despite their mm-scale displacements. Consequently, these discontinuities often have a large impact upon the flow of fluids at both micro and macro-scales. The effect of this impact in highly porous sandstone has been analyzed using a range of novel and conventional techniques, including pressure decay profile permeametry (PDPK) and positron emission tomography (PET). There are greater reductions in PDPK permeability in deformation bands relative to their host rock compared to conventional nitrogen permeametry measurements. This apparent discrepancy is the outcome of the higher spatial resolution of PDPK technique in measurements of much smaller rock volumes. There are greater porosity reductions using image analysis than conventional core techniques. These changes are reflected in a significant increase in irreducible water saturations (Swi) in deformation bands indicating much reduced fluid storage capacities. PET was used to monitor fluid flow as a function of pore volume of a sandstone plug containing deformation bands, demonstrating the direct effect of deformation bands as a potential barrier to fluid flow. The results of this study provide a detailed characterization of deformation bands at high resolution, which can be included in advanced reservoir simulation models.

Ogilvie, S. R.; Orribo, J. M.; Glover, P. W. J.

401

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

402

L to X-band scatter and emission measurements of vegetation  

NASA Astrophysics Data System (ADS)

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

Hueppi, R.; Schanda, E.

1986-08-01

403

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

NASA Astrophysics Data System (ADS)

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

Hatim, Dirar Mohamed El-Khair

2008-12-01

404

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

405

G-Band Bright Point Oscillations Underlying Chromospheric Ca II H-Line Emission  

NASA Astrophysics Data System (ADS)

We study the spatial distributions of oscillatory power and of emission in two sequences of high-cadence, high-resolution images taken by the Solar Optical Telescope on board Hinode. The sequences consist of simultaneous, co-registered G-Band (GB) and Ca II H-Line (HL) images with pixel scale 80 km and fields of view 40 x 40 Mm and 80 x 40 Mm. The first sequence has cadence 21 s over 3 hours on 2007 April 14; the other has cadence 24 s over 2 hours on 2007 March 30. Both sequences include network and internetwork at heliocentric angle 35 degrees. The G-Band images were filtered to emphasize the smallest features and thus to isolate phenomena connected to the G-Band bright points (GBPs). These appear in intergranular lanes and are associated with magnetic elements. The filtered G-Band images serve to segment areas in H-Line and magnetic images and therefore to explore their connections to the GBPs. Time averaged Morlet wavelet transforms give smoothed Fourier spectra for each spatial location in the data. Averaging over four different frequency bands highlights different physical regimes: "evolutionary” timescales (f < 1.2 mHz); evanescent frequencies just below the acoustic cutoff (2.6 mHz < f < 4.2 mHz); high frequencies just above the cutoff (5.5 mHz band. The apparent absence of magnetic shadowing suggests non-acoustic waves. An image of time-integrated H-Line emission shows strong and detailed correlation with the spatial distribution of spectral power in the GBP data, thus suggesting a possible energy source.

Lawrence, John K.; Cadavid, A. C.

2009-05-01

406

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

PubMed Central

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

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

2014-01-01

407

Preliminary feasibility study using a novel narrow-band imaging system with dual focus magnification capability in Barrett's esophagus: is the time ripe to abandon random biopsies?  

PubMed

This preliminary feasibility study assessed the utility of a novel narrow-band imaging (NBI) system (Olympus Exera III; 190 series) both as a detection and as a characterization tool in patients undergoing surveillance endoscopy for Barrett's esophagus (BE). Two hundred and twenty-one areas in 40 patients with BE were examined prospectively. The BE segment was initially evaluated with NBI overview as a 'red flag' technique. Abnormal areas identified with NBI overview were then further interrogated with NBI and a dual focus (DF) magnification system (NBI-DF) in order to aid characterization. Normal areas on NBI overview were also systematically assessed with NBI-DF systematically (four quadrants every 2?cm). A confidence system was utilized when each area was assessed with NBI-DF. All areas on NBI-DF were classified into three easily distinguishable mucosal patterns: (i) regular pits with regular microvasculature (no dysplasia); (ii) irregular pits with irregular microvasculature (early cancer/high-grade dysplasia [HGD]); and (iii) equivocal, where the endoscopist was not sure about the pattern (this could be areas with increased brownish discoloration on NBI overview and dilated vasculature but no change in caliber on NBI-DF [likely inflammation or low-grade dysplasia: LGD]). Corresponding biopsies of each area were then taken. The sensitivity (Sn), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) of both modes (NBI overview and NBI-DF) were then compared with the final histopathological diagnosis. One hundred and eighty-three of 221 areas (82.8%) did not exhibit any dysplasia on final histopathological assessment. NBI overview and NBI-DF accurately called all these areas as non-dysplastic. The 38 areas that appeared suspicious on NBI overview were also further assessed with NBI-DF: seven of seven were accurately predicted as harboring no dysplasia; nine areas were predicted as irregular, of which four harbored early cancer, one HGD, three LGD and one inflammation on final histopathology assessment. Twenty-two areas were deemed to be equivocal (final histology: 18 LGD and four inflammation). The Sn, Sp, PPV and NPV for the prediction of dysplasia/early cancer using NBI overview and NBI-DF were thus 100%, 93.8%, 68.6%, 100% and 100%, 86.2%, 73.3%, 100%, respectively. If NBI-DF was used in addition to NBI overview, biopsies would have been avoided in 190 areas (86%). In addition, all early cancers and HGD could be accurately identified. PMID:23617668

Singh, Rajvinder; Shahzad, Muhammad Asif; Tam, Willam; Goda, Kenichi; Yu, Lawrence Ho Khek; Fujishiro, Mitsuhiro; Uedo, Noriya; Ruszkiewicz, Andrew

2013-05-01

408

Four emission bands from a mixed-ligand iridium complex IrQ(ppy)2 at room temperature  

NASA Astrophysics Data System (ADS)

Four photoluminescence bands are observed from iridium complex in UV, violet, green, and red spectral regions at room temperature. Such a multiple emission is found from a mixed-ligand iridium(III) complex, (8-quinolinolato) bis(2-phenylpyridyl) iridium IrQ(ppy)2, which consists of IrQ and Ir(ppy)2 components (Q: 8-quinolinolato, ppy: phenylpyridyl). Of the four emission bands, the UV emission band with maximum at about 330 nm and the red emission band are attributed to the ligand-centered (1LC) 1n?* and metal-to-ligand charge transfer (3MLCT) 3(??*) states from IrQ, respectively, while the violet emission band with maximum at about 400 nm and the green emission band at about 513 nm are attributed to the 1LC 1(n?*) and 3MLCT 3??* states from Ir(ppy). It is suggested that (1) IrQ and Ir(ppy) generate their own emissions by the inefficient Förster energy transfer between IrQ and Ir(ppy) due to the orientation factor of nearly zero, and (2) each of IrQ and Ir(ppy) gives rise to two emissions from the singlet and triplet states by the inefficient intersystem crossing.

Tsuboi, Taiju; Huang, Duo-Fong; Chow, Tahsin J.; Huang, Wei

2014-08-01

409

High Accuracy of Narrow Band Imaging Without Magnification for the Real-Time Characterization of Polyp Histology and Its Comparison With High-Definition White Light Colonoscopy: A Prospective Study  

Microsoft Academic Search

OBJECTIVES:Standard white light colonoscopy has limited ability to differentiate between polyp types (adenomatous vs. hyperplastic). Narrow band imaging (NBI) highlights the superficial mucosal\\/vascular patterns on polyps and may facilitate real-time characterization of polyp histology. The aim of this study was to prospectively evaluate and compare the diagnostic characteristics of high-definition white light colonoscopy (HDWL) and NBI without magnification in the

Amit Rastogi; John Keighley; Vikas Singh; Peggy Callahan; Ajay Bansal; Sachin Wani; Prateek Sharma

2009-01-01

410

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

411

OH Vibrational Prompt Emission and Water Hot-Band Fluorescent Emission in C/2000 WM1 (LINEAR)  

NASA Astrophysics Data System (ADS)

Two methods for deriving cometary water production rates from ground-based high-resolution near-infrared spectra have now been developed. The water molecule can be directly sampled through "hot-band" fluorescent emission near 2.0, 2.9, 4.6, and 5.0 ? m [1]. Knowledge of the H2O rotational temperature and ortho-to-para ratio is needed to fully constrain its production rate via this method. More recently, vibrational prompt emission from OH has also been used as a proxy for water production. This method depends on the accuracy of the OH emission efficiencies derived from simultaneous observations of H2O and OH in comets C/1999 H1 (Lee) and C/2001 A2 (Linear) [2]. We report water production rates for a third comet (C/2000 WM1) based on independent analyses of H2O hot-band lines near 2.9 ? m and of OH prompt emission lines near 3046 cm-1, observed with NIRSPEC at the W. M. Keck Observatory. This comparison further reveals the capabilities and potential limitations of the two methods, while placing a special emphasis on the newer OH-based method. This work was supported by grants to M. J. Mumma (RTOP 344-32-30-07) and to H. A. Weaver and G. Chin (NAG5-12230) under NASA's Planetary Astronomy Program, and to N. Dello Russo (NAG5-10795) under NASA's Planetary Atmospheres Program. [1] Dello Russo et al. 2002, JGR, 107 (E11) 5095. [2] Bonev et al. 2004, ApJ, in press.

Bonev, B. P.; Mumma, M. J.; Dello Russo, N.; DiSanti, M. A.; Gibb, E. L.; Magee-Sauer, K.; Weaver, H. A.; Chin, G.

2004-11-01

412

Non-lte Diagnostics Of High Altitude Co2 Hot Band Emissions On Mars By The Orbiting Thermal Emission Spectrometer  

NASA Astrophysics Data System (ADS)

Using 12.5 cm-1 resolution MGS/TES limb observations from four Martian seasons (Ls=104-124, 170-190, 260-280 and 350-10), we have produced limb-geometry spec- tral averages from 40-120 km above the limb at 3 km resolution. Observations in the middle atmosphere (60-80 km) of Mars exhibit strong non-LTE IR emission in the 9.4 and 10.4um CO2 hot bands. The emission varies systematically with solar zenith angle and season. For each season we observe a single continuous non-LTE emit- ting region extending over approximately 120 degrees of latitude. At both equinoxes, the emitting region is approximately centered on the equator. The height of the mean emission is approximately independent of latitude. On the other hand, at each solstice the emitting region is centered at a low latitude in its respective summer hemisphere. The mean heights of these emission regions increase with latitude toward their respec- tive summer pole (N in northern summer, S in northern winter). We describe the CO2 non-LTE model for the Martian atmosphere which reproduces well the observed fea- tures and provides good quantitative agreement between theory and observations. The non-LTE IR radiative cooling/heating rates of Martian atmosphere for four seasons are discussed. This work was supported in part by NASA's Mars Data Analysis Program. We ac- knowledge NAS/NRC support from NASA's RRA Program.

Maguire, W. C.; Pearl, J. C.; Smith, M. D.; Conrath, B. J.; Kutepov, A. A.; Gusev, O. A.; Christensen, P. R.

413

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

414

ROSAT and ASCA Observations of the Narrow-Line SEYFER 1 GALAXY RXJ0136.9-3510 : Blueshifted Fe K? Line and Extended Soft X-Ray Emission  

NASA Astrophysics Data System (ADS)

RX J0136.9-3510 is an unusual Narrow-line Seyfert 1 galaxy (NLS1). We have detected extended ( ˜12" or ˜54 kpc) soft X-ray emission in the ROSAT HRI image, accounting for 20% of the total emission. We have also detected a highly blueshifted (7.6 keV in the source frame) Fe K? line in the ASCA SIS spectrum. This is the first detection of such a highly blueshifted line in a NLS1. Near-IR and FIR studies indicate the presence of a possible starburst component in this NLS1. Physical models of the accretion and/or outflow and the evolution of this NLS1 are discussed in the context of these results.

Ghosh, K.; Swartz, D. A.; Tennant, A. F.; Kinwah, W.

2003-05-01

415

Coherent control of spontaneous emission near a photonic band edge: A qubit for quantum computation  

NASA Astrophysics Data System (ADS)

We demonstrate the coherent control of spontaneous emission for a three-level atom located within a photonic band-gap structure with one resonant frequency near the edge of the photonic band gap. Spontaneous emission from the 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 the pump laser pulse used to create an excited state of the atom in the form of a coherent superposition of the two upper levels. Unlike the free-space case, the steady-state inversion of the atomic system is strongly dependent on the externally prescribed initial conditions. This nonzero steady-state population is achieved by virtue of the localization of light in the vicinity of the emitting atom. It is robust to decoherence effects provided that the Rabi frequency of the control laser field-atom interaction exceeds the rate of dephasing interactions. As a result, such a system may be relevant for a single-atom, phase-sensitive, optical memory device on the atomic scale. The protected electric dipole within the photonic band gap provides a basis for a qubit to encode information for quantum computations.

Woldeyohannes, Mesfin; John, Sajeev

1999-12-01

416

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

SciTech Connect

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

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

2013-09-10

417

Probing Unification with Chandra HETGS and XMM-Newton EPIC and RGS Spectroscopy of the Narrow Emission Line Galaxy NGC 2110  

NASA Astrophysics Data System (ADS)

We present results from Chandra HETGS (250 ks over two epochs) and XMM-Newton EPIC and RGS (60 ks) observations of NGC 2110, which has been historically classified as a narrow emission line galaxy. Our results support the interpretation that the source is a Seyfert 2 viewed through a patchy absorber. The nuclear X-ray spectrum of the source is best described by a power law of photon index ?~1.7, modified by absorption from multiple layers of neutral material at a large distance from the central supermassive black hole. We report the strong detections of Fe K? and Si K? lines, which are marginally resolved with the Chandra HETGS, and we constrain the emission radius of the fluorescing material to >~1 pc. There is some evidence for modest additional broadening at the base of the narrow Fe K? core with a velocity ~4500 km s-1. We find tentative evidence for ionized emission (O VIII Ly?, an O VIII RRC feature, and possibly a Ne IX forbidden line) in the Chandra MEG and XMM-Newton RGS spectra, which could be associated with the known extended X-ray emission that lies ~160 pc from the nucleus. We suggest that the 1023 cm-2 partially covering absorber originates in broad-line region clouds in the vicinity of the AGN, and that the 3×1022 cm-2 coverer is likely to have a more distant origin and have a flattened geometry in order to allow the small-scale radio jet to escape.

Evans, Daniel A.; Lee, Julia C.; Turner, T. Jane; Weaver, Kimberly A.; Marshall, Herman L.

2007-12-01

418

Emission spectra of CF3 radicals. III. Spectra and quenching of CF3 emission bands produced in the VUV photolyses of CF3Cl and CF3Br  

Microsoft Academic Search

Fluorescence in the photolysis of CF3Cl and CF3Br was investigated using various vacuum ultraviolet light sources of atomic lines (Ar, Kr, H, and O). Both UV and visible emission bands of CF3 were observed as in the case of the photolysis of CF3H. Lower v? levels of the emission bands were excited when CF3X was photolyzed by the lower energy

Masako Suto; Nobuaki Washida; Hajime Akimoto; Masatoshi Nakamura

1983-01-01

419

Control of spontaneous emission from a driven five-level atom in a photonic-band-gap reservoir  

NASA Astrophysics Data System (ADS)

We investigate the spontaneous emission properties of a five-level atom driven by a microwave field, where the two transitions are coupled to a double-band photonic-band-gap reservoir. The effects of the band-edge positions and the Rabi frequency of the microwave field on the emission spectrum are discussed. It is found that several interesting phenomena in spontaneous emission spectra such as spectral-line enhancement, spectral-line elimination, and fluorescence quenching can be controlled simply by adjusting the Rabi frequency of the driving field and the transition frequency detunings from band edges. These phenomena originate from quantum interference induced by band-edge modes and the driving field.

Liu, Ronggang

2014-05-01

420

Evaluating calibration of MODIS thermal emissive bands using infrared atmospheric sounding interferometer measurements  

NASA Astrophysics Data System (ADS)

This paper evaluates the performance of MODIS (Terra and Aqua) thermal emissive bands using current Collection 5 (C5) and newly released Collection 6 (C6) Level 1B products with a focus on relative differences between the two instruments. Data from the Infrared Atmospheric Sounding Interferometer (IASI) serves as a transfer reference. Comparison was conducted using observations from simultaneous nadir overpasses (SNO) of the Metop-A satellite and Terra/Aqua satellites. SNO times and locations were determined based on satellite orbital two-line element sets and the SNO time difference was limited to within 30 seconds. Each IASI instantaneous field of view of 12 km is co-located with multiple MODIS pixels. The corresponding IASI simulated MODIS radiances are derived by convolutions of IASI hyperspectral data and MODIS relative spectral response functions. Data analysis results show that correlations of MODIS aggregated brightness temperature (BT) and IASI simulated BT are greater than 0.9. Differences between Aqua and Terra MODIS C5 are ranging between 2 and 6 K at lower BT and are within +/-1 K at higher BT for photovoltaic bands 20-25 and 27-30. Corresponding differences from C6 products are significantly reduced to less than 2 K (except band 20). For photoconductive