WorldWideScience

Sample records for near-uv emission spectrum

  1. Uranium plasma emission coefficient in the visible and near UV.

    Science.gov (United States)

    Mack, J. M., Jr.; Usher, J. L.; Schneider, R. T.; Campbell, H. D.

    1971-01-01

    Measurements of the specific emission coefficient in the near ultra-violet and visible region of a uranium arc plasma are reported. Spatial unfolding of the intensity profile is used to determine the emission coefficient in the spectral range of 2000 A to 6000 A. The uranium partial pressure is estimated to range between .001 and .01 atmosphere, and the corresponding temperature range is 5000 - 10,000 K.

  2. Uranium plasma emission coefficient in the visible and near UV.

    Science.gov (United States)

    Mack, J. M., Jr.; Usher, J. L.; Schneider, R. T.; Campbell, H. D.

    1971-01-01

    Measurements of the specific emission coefficient in the near ultra-violet and visible region of a uranium arc plasma are reported. Spatial unfolding of the intensity profile is used to determine the emission coefficient in the spectral range of 2000 A to 6000 A. The uranium partial pressure is estimated to range between .001 and .01 atmosphere, and the corresponding temperature range is 5000 - 10,000 K.

  3. Galactic Outflows in Absorption and Emission: Near-UV Spectroscopy of Galaxies at 1

    CERN Document Server

    Erb, Dawn K; Henry, Alaina L; Martin, Crystal L

    2012-01-01

    We study large-scale outflows in a sample of 96 star-forming galaxies at 1near-UV spectroscopy of FeII and MgII absorption and emission. The average blueshift of the FeII interstellar absorption lines with respect to the systemic velocity is -85+/-10 km/s at z~1.5, with standard deviation 87 km/s; this is a decrease of a factor of two from the average blueshift measured for far-UV interstellar absorption lines in similarly selected galaxies at z~2. The profiles of the MgII 2796, 2803 lines show much more variety than the FeII profiles, which are always seen in absorption; MgII ranges from strong emission to pure absorption, with emission more common in galaxies with blue UV slopes and at lower stellar masses. Outflow velocities, as traced by the centroids and maximum extent of the absorption lines, increase with increasing stellar mass with 2-3sigma significance, in agreement with previous results. We study fine structure emission from FeII*, finding several lines of evidence in support of t...

  4. The Near-UV Pulse Profile and Spectrum of the Pulsar PSR B0656+14

    CERN Document Server

    Shibanov, Y A; Lundqvist, P; Gull, T R; Lindler, D; Shibanov, Yu.A.

    2005-01-01

    We have observed the middle-aged pulsar PSR B0656+14 with the prism and the NUV MAMA detector of the Space Telescope Imaging Spectrograph (STIS) to measure the pulsar spectrum and periodic pulsations in the near-ultraviolet (NUV). The pulsations are clearly detected, double-peaked and very similar to the optical pulse profile. The NUV pulsed fraction is 70 +/- 12%. The spectral slope of the dereddened phase-integrated spectrum in the 1800 - 3200 A range is 0.35 +/- 0.5 which together with the high pulse fraction indicates a non-thermal origin for the NUV emission. The total flux in the range 1700-3400 A is estimated to be 3.4 +/- 0.3e-15 erg/s/cm2 when corrected for E(B-V)=0.03. At a distance of 288 pc this corresponds to a luminosity 3.4e28 erg/s assuming isotropy of the emission. We compare the NUV pulse profile with observations from radio to gamma-rays. The first NUV sub-pulse is in phase with the gamma-ray pulse marginally detected with the EGRET, while the second NUV sub-pulse is similar both in shape a...

  5. HAZMAT. I. The evolution of far-UV and near-UV emission from early M stars

    Energy Technology Data Exchange (ETDEWEB)

    Shkolnik, Evgenya L. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Barman, Travis S., E-mail: shkolnik@lowell.edu, E-mail: barman@lpl.arizona.edu [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

    2014-10-01

    The spectral energy distribution, variability, and evolution of the high-energy radiation from an M dwarf planet host is crucial in understanding the planet's atmospheric evolution and habitability and in interpreting the planet's spectrum. The star's extreme-UV (EUV), far-UV (FUV), and near-UV (NUV) emission can chemically modify, ionize, and erode the atmosphere over time. This makes determining the lifetime exposure of such planets to stellar UV radiation critical for both the evolution of a planet's atmosphere and our potential to characterize it. Using the early M star members of nearby young moving groups, which sample critical ages in planet formation and evolution, we measure the evolution of the GALEX NUV and FUV flux as a function of age. The median UV flux remains at a 'saturated' level for a few hundred million years, analogous to that observed for X-ray emission. By the age of the Hyades Cluster (650 Myr), we measure a drop in UV flux by a factor of 2-3 followed by a steep drop from old (several Gyrs) field stars. This decline in activity beyond 300 Myr follows roughly t {sup –1}. Despite this clear evolution, there remains a wide range, of 1-2 orders of magnitude, in observed emission levels at every age. These UV data supply the much-needed constraints to M dwarf upper-atmosphere models, which will provide empirically motivated EUV predictions and more accurate age-dependent UV spectra as inputs to planetary photochemical models.

  6. Effect of Mg doping in Sr2 SiO4 :Eu(2)(+) nanophosphors for blue and white emission at near-UV excitation.

    Science.gov (United States)

    Dubey, Sumit; Deshmukh, Pratik; Satapathy, S; Singh, M K; Gupta, P K

    2017-08-01

    Nanophosphors of (Sr0.98-x Mgx Eu0.02 )2 SiO4 (x = 0, 0.18, 0.38, 0.58 and 0.78) were prepared through low temperature solution combustion method and their luminescence properties were studied. The emission peak for Eu(2)(+)  -doped Sr2 SiO4 nanophosphor is observed at ~490 nm and ~553 nm corresponding to two Sr(2)(+) sites Sr(I) and Sr(II) respectively for 395 nm excitation. However the addition of Mg(2)(+) dopant in Sr2 SiO4 leads to suppression of ~553 nm emission peak due to absence of energy levels of Sr (II) sites which results in a single broad emission at ~460 nm. It was shown that the emission peak blue shifted with increase in Mg concentration which may be attributed to change in crystal field environment around Sr(I) sites. Therefore, the (Mg0.78 Sr0.20 Eu0.02 )2 SiO4 nanophosphor can be used for blue emission and the Sr2 SiO4 :Eu0.04(2+) for green-yellow emission at 395 nm excitations. The Commission International de L'Eclairage (CIE) chromaticity coordinates for mixed powders of (Mg0.78 Sr0.20 Eu0.02 )2 SiO4 and Sr2 SiO4 :Eu0.04(2+) (in a 1:1 ratio) fall in the white region demonstrating the possible use of the mixture in white light generation using near-UV excitation source. Copyright © 2017 John Wiley & Sons, Ltd.

  7. White emitting polyfluorene functionalized with azide hybridized on near-UV light emitting diode for high color rendering index.

    Science.gov (United States)

    Huyal, Ilkem Ozge; Ozel, Tuncay; Koldemir, Unsal; Nizamoglu, Sedat; Tuncel, Donus; Demir, Hilmi Volkan

    2008-01-21

    We develop and demonstrate high-quality white light generation that relies on the use of a single-type simple conjugated polymer of polyfluorene functionalized with azide groups (PFA) integrated on a near-UV LED platform. The high-quality white emission from the polyfluorene is achieved by using the azide functionalization to facilitate cross-linking intentionally when cast into solid-state form. Hybridized on n-UV InGaN/GaN LED at 378 nm, the PFA emitters collectively generate a very broad down-converting photoluminescence at longer wavelengths across the entirety of the visible spectrum, yielding high color rendering indices up to 91.

  8. Near UV-Blue Excitable Green-Emitting Nanocrystalline Oxide

    Directory of Open Access Journals (Sweden)

    C. E. Rodríguez-García

    2011-01-01

    Full Text Available Green-emitting Eu-activated powders were produced by a two-stage method consisting of pressure-assisted combustion synthesis and postannealing in ammonia. The as-synthesized powders exhibited a red photoluminescence (PL peak located at =616 nm when excited with =395 nm UV. This emission peak corresponds to the 5D0→7F2 transition in Eu3+. After annealing in ammonia, the PL emission changed to an intense broad-band peak centered at =500 nm, most likely produced by 4f65d1→4f7 electronic transitions in Eu2+. This green-emitting phosphor has excitation band in the near UV-blue region (=300–450 nm. X-ray diffraction analysis reveals mainly the orthorhombic EuAlO3 and Al2O3 phases. Transmission electron microscopy observations showed that the grains are formed by faceted nanocrystals (~4 nm of polygonal shape. The excellent excitation and emission properties make these powders very promising to be used as phosphors in UV solid-state diodes coupled to activate white-emitting lamps.

  9. Characterizing the Near-UV Environment of M Dwarfs

    CERN Document Server

    Walkowicz, Lucianne M; Hawley, Suzanne L

    2007-01-01

    We report the results of our HST snapshot survey with the ACS HRC PR200L prism, designed to measure the near-UV emission in a sample of nearby M dwarfs. 33 stars were observed, spanning the mass range from 0.1 - 0.6 solar masses (T_eff ~ 2200K - 4000K) where the UV energy distributions vary widely between active and inactive stars. These observations provide much-needed constraints on models of the habitability zone and the atmospheres of possible terrestrial planets orbiting M dwarf hosts, and will be useful in refining the target selection for future space missions such as TPF. We compare our data with a new generation of M dwarf atmospheric models and discuss their implication for the chromospheric energy budget. These NUV data will also be valuable in conjunction with existing optical, FUV and X-ray data to explore unanswered questions regarding the dynamo generation and magnetic heating in low-mass stars.

  10. Spinning dust emission from ultrasmall silicates: emissivity and polarization spectrum

    CERN Document Server

    Hoang, Thiem; Lan, Nguyen Quynh

    2016-01-01

    Anomalous microwave emission (AME) is an important Galactic foreground of Cosmic Microwave Background (CMB) radiation. It is believed that the AME arises from rotational emission by spinning polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM). In this paper, we assume that a population of ultrasmall silicate grains may exist in the ISM, and quantify rotational emissivity from these tiny particles and its polarization spectrum. We found that spinning silicate nanoparticles can produce strong rotational emission when those small grains follow a log-normal size distribution. The polarization fraction of spinning dust emission from tiny silicates increases with decreasing the dipole moment per atom ($\\beta$) and can reach $P\\sim 20\\%$ for $\\beta\\sim 0.1$D at grain temperature of 60 K. We identify a parameter space $(\\beta,Y_{Si})$ for silicate nanoparticles in which its rotational emission can adequately reproduce both the observed AME and the polarization of the AME, without violating the ob...

  11. Europium-activated barium/strontium silicates for near-UV light emitting diode applications

    Energy Technology Data Exchange (ETDEWEB)

    Han, J.K. [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); Hannah, M.E.; Piquette, A. [OSRAM SYLVANIA Central Research, 71 Cherry Hill Drive Beverly, MA 01915 (United States); Micone, J. [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); Hirata, G.A. [Centro de Nanociencias y Nanotecnolgia, Universidad Nacional Autonoma de Mexico, Km. 107 Carretera Tijuana-Ensenada Apdo, Ensenada, MX CP 22860 (Mexico); Talbot, J.B. [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); University of California, San Diego, Department of Nanoengineering, La Jolla, CA 92093 (United States); Mishra, K.C. [OSRAM SYLVANIA Central Research, 71 Cherry Hill Drive Beverly, MA 01915 (United States); McKittrick, J., E-mail: jmckittrick@UCSD.Edu [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); University of California, San Diego, Department of Mechanical and Aerospace Engineering, La Jolla, CA 92093 (United States)

    2013-01-15

    This paper reports on the luminescence properties of submicron-sized green-yellow emitting (Ba{sub 1-x}Sr{sub x}Eu{sub 0.03}){sub 2}SiO{sub 4} (0{<=}x{<=}1) phosphors. These phosphors were prepared by a modified sol-gel/Pechini method. The X-ray diffraction analysis shows that the single phase products are obtained. The particle size - ranges from 200 to 500 nm with a spherical or needlelike shape depending on x. These phosphors show strong absorption in the near UV range and the photoluminescence emission spectra consist of a strong broad green-yellow band centered between 512 and 570 nm, depending on x. Furthermore, the phosphors have high quantum efficiencies: 94% for x=0 and 85% for x=0.25. The emission lifetime at 400 K is 97% of that at 40 K, demonstrating good thermal stability. - Highlights: Black-Right-Pointing-Pointer (Ba{sub 1-x}Sr{sub x}Eu{sub 0.03}){sub 2}SiO{sub 4} (0{<=}x{<=}1) phosphors were prepared by a sol-gel/Pechini method. Black-Right-Pointing-Pointer Submicron-sized (200-500 nm) particle had a spherical or needlelike morphology. Black-Right-Pointing-Pointer Strong absorption and high quantum efficiencies (85-94%) in the near UV range. Black-Right-Pointing-Pointer Emission lifetime at 400 K is 97% of that at 40 K, showing good thermal stability.

  12. Title: Near-UV behaviour of observed TNO reflectance spectra

    Science.gov (United States)

    Seccull, Tom; Fraser, Wesley Cristopher; Izawa, Matthew; Brown, Michael E.

    2016-10-01

    Observed spectra provide the best diagnostics of the surface compositions of Trans-Neptunian Objects (TNOs). We have observed the spectra of 7 TNOs, from across almost the full range of dynamical classes, using the VLT's X-Shooter spectrograph. Compared to the 5 targets in our sample which exhibit linear spectra in the UV-optical range, two of of our targets show highly unusual spectral behaviour, whereby their reflectance decreases sharply at wavelengths below ~440nm. Those same objects exhibit typically unremarkable spectra in the optical and near-IR spectral regions. In these regions where available, our observed spectra of the targets are in agreement with spectra or photometry available in the literature. Using a different solar analogue to produce our reflectance spectra does not remove the UV decrease exhibited by the two targets. Further, it appears that neither reducing the spectra with different pipelines, nor using drastically different parameters in those pipelines changes this general behaviour. Based on laboratory spectra of complex hydrocarbons it is plausible that the near-UV behaviour is the result of a surface coating of organic substances on the TNOs which exhibit it. The spectra of organics are also consistent in having a general red slope similar to that observed in the spectra of many TNOs. While laboratory spectra of some silicate substances also show a decrease in reflectance in the near-UV spectral region that is in principle consistent with our observations, those silicates do not exhibit a red slope consistent with our optical spectra. Hence, the hypothesis that silicates are present seems less likely than the hypothesis that this UV decrease is due to the presence of organics on the surfaces of these objects.

  13. Physical Retrieval of Surface Emissivity Spectrum from Hyperspectral Infrared Radiances

    Science.gov (United States)

    Li, Jun; Weisz, Elisabeth; Zhou, Daniel K.

    2007-01-01

    Retrieval of temperature, moisture profiles and surface skin temperature from hyperspectral infrared (IR) radiances requires spectral information about the surface emissivity. Using constant or inaccurate surface emissivities typically results in large retrieval errors, particularly over semi-arid or arid areas where the variation in emissivity spectrum is large both spectrally and spatially. In this study, a physically based algorithm has been developed to retrieve a hyperspectral IR emissivity spectrum simultaneously with the temperature and moisture profiles, as well as the surface skin temperature. To make the solution stable and efficient, the hyperspectral emissivity spectrum is represented by eigenvectors, derived from the laboratory measured hyperspectral emissivity database, in the retrieval process. Experience with AIRS (Atmospheric InfraRed Sounder) radiances shows that a simultaneous retrieval of the emissivity spectrum and the sounding improves the surface skin temperature as well as temperature and moisture profiles, particularly in the near surface layer.

  14. Passive remote sensing of aerosol layer height using near-UV multiangle polarization measurements

    Science.gov (United States)

    Wu, Lianghai; Hasekamp, Otto; Diedenhoven, Bastiaan; Cairns, Brian; Yorks, John E.; Chowdhary, Jacek

    2016-08-01

    We demonstrate that multiangle polarization measurements in the near-UV and blue part of the spectrum are very well suited for passive remote sensing of aerosol layer height. For this purpose we use simulated measurements with different setups (different wavelength ranges, with and without polarization, different polarimetric accuracies) as well as airborne measurements from the Research Scanning Polarimeter (RSP) obtained over the continental USA. We find good agreement of the retrieved aerosol layer height from RSP with measurements from the Cloud Physics Lidar showing a mean absolute difference of less than 1 km. Furthermore, we found that the information on aerosol layer height is provided for large part by the multiangle polarization measurements with high accuracy rather than the multiangle intensity measurements. The information on aerosol layer height is significantly decreased when the shortest RSP wavelength (410 nm) is excluded from the retrieval and is virtually absent when 550 nm is used as shortest wavelength.

  15. A study on near-UV blue photoluminescence in graphene oxide prepared by Langmuir–Blodgett method

    Energy Technology Data Exchange (ETDEWEB)

    Han, Feng; Yang, Shuming, E-mail: shuming.yang@mail.xjtu.edu.cn; Jing, Weixuan; Jiang, Zhuangde; Liu, Huan; Li, Lei

    2015-08-01

    Highlights: • GO films were deposited on substrates using LB method and reduced into rGO at 800 °C. • The PL of GO and rGO showed the near-UV blue emission. • This blue shift and decrease in PL was due to the newly formed sp{sup 2} clusters in rGO. - Abstract: The paper reports a study on a near-UV blue photoluminescence (PL) in graphene oxide (GO) films prepared by Langmuir–Blodgett (LB)-based method. GO films was reduced into reduced-graphene oxide (rGO) through thermal process at 800 °C. The surface morphology of both GO and rGO is characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). X-ray photoelectron spectroscopy (XPS) analysis shows the largely restoration of graphitic domains in GO after reduction. The photoluminescence (PL) of rGO shows the near-UV blue emission, which is blueshifted along with luminescent decreased as compared to GO. This blueshift and decrease in PL is mainly due to the newly formed sp{sup 2} clusters in rGO, which established percolation pathways between the sp{sup 2} clusters already present.

  16. Biomarkers in disk-averaged near-UV to near-IR Earth spectra using Earthshine observations

    CERN Document Server

    Hamdani, S; Foellmi, C; Berthier, J; Billeres, M; Briot, D; Riaud, P; Schneider, J; Hamdani, Slim; Arnold, Luc

    2006-01-01

    We analyse the detectability of vegetation on a global scale on Earth's surface. Considering its specific reflectance spectrum showing a sharp edge around 700 nm, vegetation can be considered as a potential global biomarker. This work, based on observational data, aims to characterise and to quantify this signature in the disk-averaged Earth's spectrum. Earthshine spectra have been used to test the detectability of the "Vegetation Red Edge" (VRE) in the Earth spectrum. We obtained reflectance spectra from near UV (320 nm) to near IR (1020 nm) for different Earth phases (continents or oceans seen from the Moon) with EMMI on the NTT at ESO/La Silla, Chile. We accurately correct the sky background and take into account the phase-dependent colour of the Moon. VRE measurements require a correction of the ozone Chappuis absorption band and Rayleigh plus aerosol scattering. Results : The near-UV spectrum shows a dark Earth below 350 nm due to the ozone absorption. The Vegetation Red Edge is observed when forests are...

  17. Synthesis and luminescent features of NaCaPO{sub 4}:Tb{sup 3+} green phosphor for near UV-based LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Ratnam, B.V. [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Jayasimhadri, M., E-mail: jayaphysics@yahoo.com [Department of Applied Physics, Delhi Technological University, Delhi 110 042 (India); Bhaskar Kumar, G. [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Jang, Kiwan, E-mail: kwjang@changwon.ac.kr [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Kim, S.S. [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Lee, Y.I.; Lim, J.M.; Shin, D.S. [Department of Chemistry, Changwon National University, Changwon 641-773 (Korea, Republic of); Song, T.K. [School of Nano and Advanced Materials Engineering, Changwon National University, Changwon 641-773 (Korea, Republic of)

    2013-07-05

    Highlights: ► Successfully synthesized orthorhombic phase of NaCaPO{sub 4} (NCP) phosphors ► Structural and Luminescent properties have been investigated. ► In the excitation spectrum, {sup 7}F{sub 6}→{sup 5}G{sub 6} transition at 370 nm exhibit highest intensity. ► CIE coordinates of Tb{sup 3+}: NCP phosphor indicate green light emission in CIE diagram. ► Hence, Tb{sup 3+} doped NaCaPO{sub 4} is suitable for UV based pc-LEDs. -- Abstract: An efficient green emitting Tb{sup 3+} doped NaCaPO{sub 4} (NCP) phosphor was synthesized by using conventional solid-state reaction for solid-state lighting applications. X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), FT-IR, emission and excitation properties were extensively investigated for NCP phosphors. X-ray diffraction analysis confirmed the formation of NaCaPO{sub 4} with orthorhombic structure. The excitation spectrum consists of strong 4f–4f transition at around 370 nm, which has higher intensity than the f–d transition. Emission spectra indicated that this phosphor can be efficiently excited by UV light in the range from 250 to 400 nm, and shows strong emission band centered at 547 nm. Analysis of the emission spectra with different Tb{sup 3+} concentrations revealed that the optimum dopant concentration for these NCP phosphors is about 5 mol% of Tb{sup 3+}. Diminishing of {sup 5}D{sub 3} level and increasing of {sup 5}D{sub 4} level emission intensity with the Tb{sup 3+} concentration explained successfully. The emission color was analyzed and confirmed with the help of chromaticity coordinates and color temperature. The excellent luminescent properties of NaCaPO{sub 4}:Tb{sup 3+} phosphor makes it as a potential green phosphor upon near-UV LED excitation.

  18. Uranium M x-ray emission spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Keski-Rahkonen, O.; Krause, M.O.

    1977-03-01

    The uranium M x-ray spectrum from a thick metallic target excited by 12-keV electrons was measured by the PAX (photoelectron spectrometry for the analysis of x rays) technique. Energies of the strongest lines were obtained with an accuracy of 0.1 eV using Ag L..beta../sub 1/ and Ag L..cap alpha../sub 1/ as standards. Widths of the uranium lines were obtained by deconvoluting the measured Voigt profiles, and the experimental values were found to agree satisfactorily with McGuire's Hartree-Slater predictions. Natural widths of 4.0(3) and 3.8(3) eV were derived for the M/sub 4/ and M/sub 5/ levels, respectively, and the energies of the M/sub 4/, M/sub 5/, N/sub 2/, and N/sub 3/ levels in uranium metal were determined. Relative intensities of the M lines were measured, and branching ratios were found to be in fair agreement with relativistic Hartree-Slater predictions. The satellite structures of the M..cap alpha../sub 1/ and M..beta.. lines were interpreted in terms of the pertinent multiple-hole configurations. Finally, an approximate analytic expression for the Voigt half-width and its graphical representation are given.

  19. Emission spectrum of soft massless states from heavy superstring

    CERN Document Server

    Kawamoto, Shoichi

    2013-01-01

    We calculate emission rates of various bosonic/fermionic soft massless states of open/closed superstring from an ensemble of a highly excited open/closed superstring in the flat background. The resulting spectrum shows thermal distributions at the Hagedorn temperature. We find greybody factors for each process and observe their relation to the ones from blackholes.

  20. Non-LTE modeling of the near UV band of late-type stars

    CERN Document Server

    Short, C Ian

    2008-01-01

    We investigate the ability of both LTE and Non-LTE models to fit the near UV band absolute flux distribution and individual spectral line profiles of three standard stars for which high quality spectrophotometry and high resolution spectroscopy are available: The Sun (G2 V), Arcturus (K2 III), and Procyon (F5 IV-V). We investigate 1) the effect of the choice of atomic line list on the ability of NLTE models to fit the near UV band flux level, 2) the amount of a hypothesized continuous thermal absorption extinction source required to allow NLTE models to fit the observations, and 3) the semi-empirical temperature structure required to fit the observations with NLTE models and standard continuous near UV extinction. We find that all models that are computed with high quality atomic line lists predict too much flux in the near UV band for Arcturus, but fit the warmer stars well. The variance among independent measurements of the solar irradiance in the near UV is sufficiently large that we cannot definitely conc...

  1. Luminescent properties of red-light-emitting phosphors CaWO4 : Eu3+, Li+ for near UV LED

    Indian Academy of Sciences (India)

    F B Xiong; H F Lin; L J Wang; H X Shen; Y P Wang; W Z Zhu

    2015-12-01

    A series of red phosphors Ca1−2WO4 : Eu3+, Li+ ( = 0.01, 0.02, 0.04, 0.06, 0.12, 0.20 and 0.30) in pure phase were synthesized via high-temperature solid-state reaction and their luminescent properties were investigated. For comparison, the 6 mol% Eu3+-doped CaWO4 was also obtained and investigated. The crystal structures of these phosphors were characterized by powder X-ray diffraction, and the luminescent properties of Eu3+-, Li+-codoped CaWO4 were investigated by diffuse reflectance spectra, photoluminescence emission spectra, photoluminescence excitation spectra, and the Commission International de L' Eclairage (CIE) chromaticity indexes. These spectra illustrated that Eu3+-, Li+-codoped CaWO4 phosphors could effectively be excited by a 270 nm ultraviolet (UV) or 394 nm near UV chip, and exhibit red emission originated from the 5D0 $\\rightarrow$ 7F ( = 1 and 2) transitions of Eu3+. The fluorescent intensities of red emission band centred at 610 nm of 6 mol% Eu3+-, Li+-codoped CaWO4 were about 1.27 times stronger than that of 6 mol% Eu3+-doped CaWO4 under 394 nm excitation. The 12 mol% doping concentration of Eu3+ ions in CaWO4 is optimum when excited at 394 nm, while excited at 270 nm the sample with 6 mol% was the best one. The concentration quenching mechanism could be attributed to the dipole–dipole interaction between the Eu3+ ions. The CIE colour coordinates can be tuned from yellowish red to deep red with varying concentrations of Eu3+. The present work suggests that Eu3+-, Li+-codoped CaWO4 as red phosphors exhibit great potential application in the near UV excited white-light-emitting diode.

  2. Significant improvement of near-UV electroluminescence from ZnO quantum dot LEDs via coupling with carbon nanodot surface plasmons.

    Science.gov (United States)

    Zhang, Cen; Zhu, Feifei; Xu, Haiyang; Liu, Weizhen; Yang, Liu; Wang, Zhongqiang; Ma, Jiangang; Kang, Zhenhui; Liu, Yichun

    2017-10-05

    Short-wavelength LEDs, a hot research topic in modern optoelectronics, have attracted tremendous attention in recent years because of their great application potential in both civil and military domains. Compared to conventional metallic surface-plasmons (SPs), carbon nanodot (CD) SPs with less optical loss and low cost, broader SP resonant frequency and good biocompatibility are expected to provide more prominent luminescence enhancement for light emitters. Herein, SP-enhanced near-UV emission quantum dot LEDs (Q-LED) were fabricated via introducing CDs into p-GaN/Al2O3/ZnO Q-LEDs by optimizing the molar ratio of ZnO quantum dots to CDs and a significant enhancement (∼20-fold) of the near-UV electroluminescence (EL) intensity from the ZnO-based Q-LEDs was achieved. Time-resolved spectroscopy studies reveal that the observed luminescence enhancement arises due to the resonant coupling between ZnO excitons and CD SPs. The current study not only demonstrates a feasible way to acquire near-UV emission from all-inorganic Q-LEDs, but also provides an effective strategy to enhance the EL intensity of these QD light emitters, which can further be extended to other types of light-emitting devices to improve EL efficiency.

  3. Observations of the spectrum of the interplanetary dust emission

    Science.gov (United States)

    Salama, A.; de Bernardis, P.; Masi, S.; Moreno, G.

    Published data from satellite (IRAS), rocket-borne (ZIP), and balloon-borne (ARGO) spectroscopic observations of interplanetary dust emission in the FIR are compiled and analyzed, extending the spatial-distribution results of Salama et al. (1986) to evaluate the possible role of silicate and graphite grains in determining the FIR spectrum. The zodiacal dust spectra in the ecliptic plane at solar elongations epsilon = 45 and 90 deg are calculated on the basis of theoretical models and compared with the observations. A model based on a flat distribution of 10-micron-diameter silicate grains is shown to reproduce the observed spectrum at epsilon = 45 deg but not at epsilon = 90 deg, where a model with a mixture of silicate and graphite grains gives a better, but still unsatisfactory fit to the observations.

  4. Emission spectrum of the atomic chain excited by channeled particle

    CERN Document Server

    Epp, V

    2014-01-01

    Basic properties of radiation of the atomic chains excited by a channeled particle are considered. Using a very simple two-dimensional model of a crystal lattice we have shown that the main part of this radiation is generated on the frequency of oscillations of a channeled particle between the crystal planes, shifted by the Doppler effect. Spectral and angular distribution and spectral distribution of the radiation of the atomic chain excited by channeled particle were calculated. Emission spectrum of the atomic chain excited by channeled particle was plotted.

  5. Photometric observation of HAT-P-16b in the near-UV

    CERN Document Server

    Pearson, Kyle A; Sagan, Thomas A G

    2014-01-01

    We present the first primary transit light curve of the hot Jupiter HAT-P-16b in the near-UV photometric band. We observed this object on December 29,2012 in order to update the transit ephemeris, constrain its planetary parameters and search for magnetic field interference. Vidotto et al. (2011a) postulate that the magnetic field of HAT-P-16b can be constrained if its near-UV light curve shows an early ingress compared to its optical light curve, while its egress remains unchanged. However, we did not detect an early ingress in our night of observing when using a cadence of 60 seconds and an average photometric precision of 2.26mmag. We find a near-UV planetary radius of Rp=1.274+-0.057RJup which is consistent with its near-IR radius of Rp=1.289+-0.066RJup (Buchhave et al., 2010). We developed an automated reduction pipeline and modeling package to process our data. The data reduction package synthesizes a set of IRAF scripts to calibrate images and perform aperture photometry. The modeling package utilizes ...

  6. Near-UV and optical observations of the transiting exoplanet TrES-3b

    CERN Document Server

    Turner, Jake D; Hardegree-Ullman, Kevin K; Carleton, Timothy M; Walker-LaFollette, Amanda M; Crawford, Benjamin E; Smith, Carter-Thaxton W; McGraw, Allison M; Small, Lindsay C; Rocchetto, Marco; Cunningham, Kathryn I; Towner, Allison P M; Zellem, Robert; Robertson, Amy N; Guvenen, Blythe C; Schwarz, Kamber R; Hardegree-Ullman, Emily E; Collura, Daniel; Henz, Triana N; Lejoly, Cassandra; Richardson, Logan L; Weinand, Michael A; Taylor, Joanna M; Daugherty, Michael J; Wilson, Ashley A; Austin, Carmen L

    2012-01-01

    We observed nine primary transits of the hot Jupiter TrES-3b in several optical and near-UV photometric bands from 2009 June to 2012 April in an attempt to detect its magnetic field. Vidotto, Jardine and Helling suggest that the magnetic field of TrES-3b can be constrained if its near-UV light curve shows an early ingress compared to its optical light curve, while its egress remains unaffected. Predicted magnetic field strengths of Jupiter-like planets should range between 8 G and 30 G. Using these magnetic field values and an assumed B_star of 100 G, the Vidotto et al. method predicts a timing difference of 5-11 min. We did not detect an early ingress in our three nights of near-UV observations, despite an average cadence of 68 s and an average photometric precision of 3.7 mmag. However, we determined an upper limit of TrES-3b's magnetic field strength to range between 0.013 and 1.3 G (for a 1-100 G magnetic field strength range for the host star, TrES-3) using a timing difference of 138 s derived from the N...

  7. Star formation in the hosts of GHz peaked spectrum and compact steep spectrum radio galaxies

    NARCIS (Netherlands)

    Labiano, A.; O'Dea, C. P.; Barthel, P. D.; Vries, W. H. de; Baum, S. A.

    2007-01-01

    Abstract: AIMS: Search for star formation regions in the hosts of potentially young radio galaxies (Gigahertz Peaked Spectrum and Compact Steep Spectrum sources). METHODS: Near-UV imaging with the Hubble Space Telescope Advanced Camera for Surveys.} RESULTS: We find near-UV light which could be the

  8. KCa4(BO33:Ln3+ (Ln = Dy, Eu, Tb phosphors for near UV excited white–light–emitting diodes

    Directory of Open Access Journals (Sweden)

    Allu Amarnath Reddy

    2013-02-01

    Full Text Available A series of doped KCa4(BO33:Ln3+ (Ln: Dy, Eu and Tb compositions were synthesized by solid–state reaction method and their photoluminescent properties were systematically investigated to ascertain their suitability for application in white light emitting diodes. The X–ray diffraction (XRD and nuclear magnetic resonance (MAS–NMR data indicates that Ln3+–ions are successfully occupied the non–centrosymmetric Ca2+ sites, in the orthorhombic crystalline phase of KCa4(BO33 having space group Ama2, without affecting the boron chemical environment. The present phosphor systems could be efficiently excitable at the broad UV wavelength region, from 250 to 350 nm, compatible to the most commonly available UV light–emitting diode (LED chips. Photoluminescence studies revealed optimal near white–light emission for KCa4(BO33 with 5 wt.% Dy3+ doping, while warm white–light (CIE; X = 0.353, Y = 0.369 is obtained at 1wt.% Dy3+ ion concentration. The principle of energy transfer between Eu3+ and Tb3+ also demonstrates the potential white–light from KCa4(BO33:Eu3+,Tb3+ phosphor. Whereas, single Tb3+ and Eu3+–doped systems showed bright green (Tb3+ and red (Eu3+ emissions, respectively. Having structural flexibility along with remarkable chemical/thermal stability and suitable quantum efficiency these phosphors can be promising candidates as white–light–emitter for near UV LEDs.

  9. Spectrum analysis of national greenhouse gas emission: a case study of Germany

    Energy Technology Data Exchange (ETDEWEB)

    Su, Meirong [Dongguan University of Technology, School of Chemistry and Environmental Engineering, Dongguan, Guangdong Province (China); Beijing Normal University, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Beijing (China); Technical University of Munich, Strategic Landscape Planning and Management, Freising (Germany); Pauleit, Stephan; Xu, Chao [Technical University of Munich, Strategic Landscape Planning and Management, Freising (Germany)

    2016-10-15

    It is essential to abstract the key information from accounting results of greenhouse gas (GHG) emissions because it can provide a highly generalized and clear picture of GHG emissions, which is especially helpful for the public and policy makers. To clearly display the composition of GHG emissions, the concept of spectrum analysis is introduced and defined in this paper. Next, a multilayer analysis framework for national GHG emissions was proposed, which is represented by a pyramid of three layers: total emissions (first layer), emissions decomposed by gas type or sector (second layer), and emissions decomposed by both gas type and sector (third layer). Based on the analysis results from the first to third layers, the main compositional information of national GHG emissions was gradually summarized and analyzed until a spectrum of GHG emissions was acquired. The spectrum of GHG emissions displays the compositional structure of national GHG emissions in the different layers, which is helpful in identifying priorities for emissions reduction. A case study of Germany's GHG emissions during 1990-2012 was conducted, which indicated that CO{sub 2} and the energy sector were the biggest contributors to the total GHG emissions. Some suggestions for reducing GHG emissions are offered based on the obtained results. And the potential development of spectrum analysis for GHG emissions is also expected from aspects of both research and technology. (orig.)

  10. [Field measurement of Gobi surface emissivity spectrum at Dunhuang calibration site of China].

    Science.gov (United States)

    Zhang, Yong; Li, Yuan; Rong, Zhi-guo; Hu, Xiu-qing; Zhang, Li-jun; Liu, Jing-jing

    2009-05-01

    Gobi surface emissivity spectrum of Dunhuang radiometric calibration site of China is one of the key factors to calibrate the thermal infrared remote sensors using land surface. Based on the iterative spectrally smooth temperature/emissivity separation (ISSTES)algorithm, Dunhuang Gobi surface emissivity spectrum was measured using BOMEM MR154 Fourier transform spectroradiometer and Infrared Golden Board. Emissivity spectrum data were obtained at different time and locations. These spectrum data were convolved with the channel response function of CE312 radiometer and compared with the channel emissivity measured by the same instrument. The results showed that the difference between these two kinds of channel emissivity was within 0.012 and exhibited a good consistency. With these measured emissivity spectra, all of the mainstream thermal infrared remote sensors can be calibrated using Dunhuang Gobi surface at radiometric calibration site of China.

  11. Synthesis and luminescence properties of a novel phosphor Ca2-x/2Si1-xPxO4:Eu2+for near UV-excited white-light-emitting diodes

    Institute of Scientific and Technical Information of China (English)

    訾文文; 崔天杰; 于泓; 李琳琳; 甘树才; 徐学纯

    2013-01-01

    A novel green-emitting phosphor, Eu2+-doped Ca2-x/2Si1-xPxO4 (0.25≤x≤0.30), was prepared through a conventional solid-state reaction. X-ray diffraction (XRD), photoluminescence (PL) and decay studies were employed to characterize the sample, which was assigned to P63mc space group in the hexagonal system. The effect of P-doping on theα-Ca2SiO4 was studied and P2O5 broken down by the raw material of (NH4)2HPO4 played an important role in stabilizingα-Ca2SiO4 which can only be stable at high tem-perature. The XRD patterns of the Ca2-x/2Si1-xPxO4 host were found pure and optimized when the mole fraction of P2O5 was 14.5%. The diffuse reflectance spectra of the Ca1.855Si0.71P0.29O4 and Ca1.845Si0.71P0.29O4:0.01Eu2+covered the spectral region of 230-400 nm, implying that the phosphor was suitable for UV or near-UV LED excitation. The phosphor could be effectively excited in the near UV region with the maximum at 372 nm. The emission spectrum of the Ca1.845Si0.71P0.29O4:0.01Eu2+phosphor showed an asymmet-rical single intensive band centered at 513 nm, which corresponded to the 4f65d1→4f7 transition of Eu2+. Eu2+ions might occupy two types of Ca2+sites in the Ca1.855Si0.71P0.29O4 lattice and form two corresponding emission centers, which led to the asymmetrical emis-sion of Eu2+in Ca1.855Si0.71P0.29O4. The effects of Eu2+-doped concentration in Ca1.855-xSi0.71P0.29O4:xEu2+on the PL were also dis-cussed, the optimum doping concentration of Eu2+was 1 mol.%and the critical distance of the energy transfer was also calculated by the concentration-quenching method. The non-radiative energy transfer between Eu2+seemed to be caused by the multipole-multipole interaction. The fluorescence lifetime of Eu2+was found to be 0.55711μs. The results suggested that these phosphors might be prom-ising candidates used for near UV light excited white LEDs.

  12. Near-uv and optical observations of the transiting hot Jupiter WASP-1b

    Science.gov (United States)

    Pearson, K. A.; Zellem, R.; Biddle, L. I.; Amaya, H.; Watson, Z.; Griffith, C.; Small, L.; Hume, J.

    2014-03-01

    We present simultaneous near-UV (U-band) and optical (B-band) photometric observations of the primary transit of the highly irradiated, hot-Jupiter WASP-1b on the Kuiper 61" telescope. We use our results to search for timing transit variations, which would indicate additional planets, and provide new constraints on WASP-1b's physical parameters. Assuming the opacity at these two photometric bands is dominated by Rayleigh scattering by molecular hydrogen, we can place strong upper limits on its radius. Such constraints can limit the degeneracy between an exoplanet's physical radius and atmospheric composition in radiative transfer retrievals. Additionally its host star is chromospherically active and WASP-1b orbits within in the co-rotation radius of the star making it likely that WASP-1b has a bowshock. Therefore, we will search for a planetary magnetic field as indicated by an early ingress in the near-UV light curve compared to the optical due to the bowshock itself. Such measurements would confirm the observational methodology of detecting magnetic fields around transiting exoplanets, place an upper limit on WASP-1b's magnetic field strength, and confirm previous theoretical estimations of hot Jupiter magnetic fields.

  13. A sensitive spectral survey of interstellar features in the near-UV [3050-3700{\\AA}

    CERN Document Server

    Bhatt, Neil Hemant

    2014-01-01

    We present a comprehensive and sensitive unbiased survey of interstellar features in the near-UV range (3050-3700 {\\AA}). We combined a large number of VLT/UVES archival observations of a sample of highly reddened early type stars -- typical diffuse interstellar band (DIB) targets -- and unreddened standards. We stacked the individual observations to obtain a reddened "superspectrum" in the interstellar rest frame with a signal-to-noise (S/N) ratio exceeding 1500. We compared this to the analogous geocentric and stellar rest frame superspectra as well as to an unreddened superspectrum to find interstellar absorption features. We find 30 known features (11 atomic and 19 molecular) and tentatively detect up to 7 new interstellar absorption lines of unknown origin. Our survey is sensitive to narrow and weak features; telluric residuals preclude us from detecting broader features. For each sightline, we measured fundamental parameters (radial velocities, line widths, and equivalent widths) of the detected interst...

  14. Improvements to the OMI Near-uv Aerosol Algorithm Using A-train CALIOP and AIRS Observations

    Science.gov (United States)

    Torres, O.; Ahn, C.; Zhong, C.

    2014-01-01

    The height of desert dust and carbonaceous aerosols layers and, to a lesser extent, the difficulty in assessing the predominant size mode of these absorbing aerosol types, are sources of uncertainty in the retrieval of aerosol properties from near UV satellite observations. The availability of independent, near-simultaneous measurements of aerosol layer height, and aerosol-type related parameters derived from observations by other A-train sensors, makes possible the direct use of these parameters as input to the OMI (Ozone Monitoring Instrument) near UV retrieval algorithm. A monthly climatology of aerosol layer height derived from observations by the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) sensor, and real-time AIRS (Atmospheric Infrared Sounder) CO observations are used in an upgraded version of the OMI near UV aerosol algorithm. AIRS CO measurements are used as a reliable tracer of carbonaceous aerosols, which allows the identification of smoke layers in areas and times of the year where the dust-smoke differentiation is difficult in the near-UV. The use of CO measurements also enables the identification of elevated levels of boundary layer pollution undetectable by near UV observations alone. In this paper we discuss the combined use of OMI, CALIOP and AIRS observations for the characterization of aerosol properties, and show a significant improvement in OMI aerosol retrieval capabilities.

  15. Diffuse galactic continuum emission measured by COMPTEL and the cosmic-ray electron spectrum

    Science.gov (United States)

    Strong, A. W.; Diehl, R.; Schoenfelder, V.; Varendorff, M.; Youssefi, G.; Bloemen, H.; Hermsen, W.; De Vries, C.; Morris, D.; Stacy, J. G.

    1994-01-01

    Diffuse galactic continuum gamma-ray emission in the 0.75-30 MeV range from the inner Galaxy has been studied using data from COMPTEL on the Compton Gamma-Ray Observatory. Observations of the inner Galaxy from the Sky Survey have been used. The imaging properties of COMPTEL enable spatial analysis of the gamma-ray distribution using model fitting. A model based on atomic and molecular gas distributions in the Galaxy has been used to derive the emissivity spectrum of the gamma-ray emission and this spectrum is compared with theoretical estimates of bremsstrahlung emission from cosmic-ray electrons.

  16. Near-UV Transmittance of Basalt Dust as an Analog of the Martian Regolith: Implications for Sensor Calibration and Astrobiology

    Directory of Open Access Journals (Sweden)

    J. Martínez-Frías

    2006-06-01

    Full Text Available The Martian regolith is exposed to solar irradiation in the near-UV (200-390 nm.Basalt is one of the main components of the dust on Mars surface. The near-UV irradiationof basalt dust on Mars is simulated experimentally in order to determine the transmittance asa function of the mass and thickness of the dust. This data can serve to quantify theabsorption of dust deposited on sensors aiming to measure the UV intensity on Marssurface. The minimum thickness of the dust that corresponds to near-zero-transmittance inthe near-UV is measured. Hypothetical Martian microorganisms living on the dusty regolithat deeper layers would be preserved from the damaging solar UV irradiation.

  17. A europium(III) organic ternary complex applied in fabrication of near UV-based white light-emitting diodes

    Science.gov (United States)

    Wang, H.; He, P.; Liu, S.; Shi, J.; Gong, M.

    2009-10-01

    A β-diketone, 2-acetylfluorene-4,4,4-trifluorobutane-1,3-dione (HAFTFBD), and its three europium(III) complexes, Eu(AFTFBD)3ṡ2H2O, Eu(AFTFBD)3(TPPO)2 and Eu(AFTFBD)3phen, were designed and synthesized, where TPPO was triphenylphosphine oxide and phen was 1,10-phenanthroline. The complexes were characterized by IR, UV-visible, photoluminescence (PL) spectroscopy and thermogravimetric analysis (TGA). The results show that the Eu(III) complexes exhibit a high thermal stability,and wide and strong excitation bands when monitored at 613 nm. Excited by ˜395 nm near UV light, the complexes emitted strong and characteristic red light due to f- f transitions of the central Eu3+ ion, and no emission from the ligands was found. The photoluminescence mechanism of the europium(III) complexes was investigated and proposed as a ligand-sensitized luminescence process. Among the three europium(III) complexes, Eu(AFTFBD)3phen exhibits the highest thermal stability and the most excellent photoluminescence properties. A bright red light-emitting diode was fabricated by coating the Eu(AFTFBD)3phen complex onto an ˜395 nm-emitting InGaN chip, and the LED showed appropriate CIE chromaticity coordinates ( x=0.66, y=0.33). A white LED with CIE chromaticity coordinates ( x=0.32, y=0.32) was prepared with Eu(AFTFBD)3phen as red phosphor, indicating that Eu(AFTFBD)3phen can be applied as a red component for fabrication of near ultraviolet-based white light-emitting diodes.

  18. Amplified spontaneous emission spectrum and gain characteristic of a two-electrode semiconductor optical amplifier*

    Institute of Scientific and Technical Information of China (English)

    Wang Hanchao; Huang Lirong; Shi Zhongwei

    2011-01-01

    A two-electrode multi-quantum-well semiconductor optical amplifier is designed and fabricated. The amplified spontaneous emission (ASE) spectrum and gain were measured and analyzed. It is shown that the ASE spectrum and gain characteristic are greatly influenced by the distribution of the injection current density. By changing the injection current density of two electrodes, the full width at half maximum, peak wavelength, peak power of the ASE spectrum and the gain characteristic can be easily controlled.

  19. A Two-stage Polynomial Method for Spectrum Emissivity Modeling

    OpenAIRE

    Qiu, Qirong; Liu, Shi; Teng, Jing; Yan, Yong

    2015-01-01

    Spectral emissivity is a key in the temperature measurement by radiation methods, but not easy to determine in a combustion environment, due to the interrelated influence of temperature and wave length of the radiation. In multi-wavelength radiation thermometry, knowing the spectral emissivity of the material is a prerequisite. However in many circumstances such a property is a complex function of temperature and wavelength and reliable models are yet to be sought. In this study, a two stages...

  20. The Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068

    Science.gov (United States)

    2005-04-10

    THE FAR-INFRARED EMISSION LINE AND CONTINUUM SPECTRUM OF THE SEYFERT GALAXY NGC 10681 Luigi Spinoglio Istituto di Fisica dello Spazio Interplanetario...circumnuclear ring of 1500–1600 in radius within the last 4–40 Myr. CO interferometer observa- tions revealed molecular gas very close to the nucleus...from 43 to 197 m showing both atomic and molecular emission lines (x 2). We model the composite UV to far-IR atomic emission-line and continuum

  1. Identification and quantitation of near-UV absorbing compounds (S-320) in a hermatypic scleractinian

    Science.gov (United States)

    Dunlap, W. C.; Chalker, B. E.

    1986-12-01

    Reef-building corals from shallow waters are known to contain a suite of water soluble compounds (collectively named S-320) which strongly absorb near-UV light. Compounds of this type have now been isolated from the Pacific staghor coral Acropora formosa and identified as a series of mycosporine-like amino acids including mycosporine-Gly (λmax=310nm), palythine (λmax=320nm) and palythinol (λmax=332nm). These compounds were separated and quantified by high-performance liquid chromatography. Serial extraction efficiencies were calculated using a simple formula which is derived herein. For 12-cm long coral branches collected from a depth of 3 m at Rib Reef, Great Barrier Reef, Australia (146° 53'E, 18° 29'S) the average concentrations of mycosporine-Gly, palythine, and palythinol were 37.8, 56.4 and 0.895 nmol per mg coral protein, respectively. The coral samples can be stored at-20°C for at least 144 days without degradation of the mycosporinelike amino acids.

  2. Liquid crystal chiroptical polarization rotators for the near-UV region: theory, materials, and device applications

    Science.gov (United States)

    Saulnier, D.; Taylor, B.; Marshall, K. L.; Kessler, T. J.; Jacobs, S. D.

    2013-09-01

    The helical structure of a chiral-nematic liquid crystal (CLC) material produces a number of interesting optical properties, including selective reflection and optical rotatory power. To take advantage of the high optical rotation near the selective reflection peak for applications in the UV, either large concentrations of chiral components or those possessing very large helical twisting powers (HTP's) are necessary. It is difficult to find chiral twisting agents with high HTP that do not degrade the UV transmission. We report what we believe to be the first experimental observation of extraordinarily high optical rotation (LC) layer thickness. Using this model, the optical rotation at λ = 355 nm for the 1% CB 15/ZLI-1646 mixture is determined computationally, with the results in agreement with experimental data obtained by evaluating a series of wedged cells using an areal mapping, Hinds Exicor 450XT Mueller Matrix Polarimeter. This finding now opens a path to novel LC optics for numerous near-UV applications. One such envisioned application for this class of materials would be UV distributed polarization rotators (UV-DPR's) for largeaperture, high-peak-power lasers.

  3. The angular power spectrum of radio emission at 2.3 GHz

    CERN Document Server

    Giardino, G; Fosalba, P; Górski, K M; Jonas, J L; O'Mullane, W; Tauber, J A

    2001-01-01

    We have analysed the Rhodes/HartRAO survey at 2326 MHz and derived the global angular power spectrum of Galactic continuum emission. In order to measure the angular power spectrum of the diffuse component, point sources were removed from the map by median filtering. A least-square fit to the angular power spectrum of the entire survey with a power law spectrum C_l proportional to l^{-alpha}, gives alpha = 2.43 +/- 0.01 for l = 2-100. The angular power spectrum of radio emission appears to steepen at high Galactic latitudes and for observed regions with |b| > 20 deg, the fitted spectral index is alpha = 2.92 +/- 0.07. We have extrapolated this result to 30 GHz (the lowest frequency channel of Planck) and estimate that no significant contribution to the sky temperature fluctuation is likely to come from synchrotron at degree-angular scales

  4. Anomalous Microwave Emission from Spinning Dust and its Polarization Spectrum

    CERN Document Server

    Hoang, Thiem

    2015-01-01

    Nearly twenty years after the discovery of anomalous microwave emission (AME) that contaminates to the cosmic microwave background (CMB) radiation, its origin remains inconclusive. Observational results from numerous experiments have revealed that AME is most consistent with spinning dust emission from rapidly spinning ultrasmall interstellar grains. In this paper, I will first review our improved model of spinning dust, which treats realistic dynamics of wobbling non-spherical grains, impulsive interactions of grains with ions in the ambient plasma, and some other important effects. I will then discuss recent progress in quantifying the polarization of spinning dust emission from polycyclic aromatic hydrocarbons. I will finish with a brief discussion on remaining issues about the origins of AME.

  5. The Supercritical Pile Model: Prompt Emission Across the Electromagnetic Spectrum

    Science.gov (United States)

    Kazanas, Demos; Mastichiadis, A.

    2008-01-01

    The "Supercritical Pile" GRB model is an economical model that provides the dissipation necessary to convert explosively the energy stored in relativistic protons in the blast wave of a GRB into radiation; at the same time it produces spectra whose luminosity peaks at 1 MeV in the lab frame, the result of the kinematics of the proton-photon - pair production reaction that effects the conversion of proton energy to radiation. We outline the fundamental notions behind the "Supercritical Pile" model and discuss the resulting spectra of the prompt emission from optical to gamma-ray energies of order Gamma^2 m_ec^2, (Gamma is the Lorentz factor of the blast wave) present even in the absence of an accelerated particle distribution and compare our results to bursts that cover this entire energy range. Particular emphasis is given on the emission at the GLAST energy range both in the prompt and the afterglow stages of the burst.

  6. The Supercritical Pile Model: Prompt Emission Across the Electromagnetic Spectrum

    Science.gov (United States)

    Kazanas, Demos; Mastichiadis, A.

    2008-01-01

    The "Supercritical Pile" GRB model is an economical model that provides the dissipation necessary to convert explosively the energy stored in relativistic protons in the blast wave of a GRB into radiation; at the same time it produces spectra whose luminosity peaks at 1 MeV in the lab frame, the result of the kinematics of the proton-photon - pair production reaction that effects the conversion of proton energy to radiation. We outline the fundamental notions behind the "Supercritical Pile" model and discuss the resulting spectra of the prompt emission from optical to gamma-ray energies of order Gamma^2 m_ec^2, (Gamma is the Lorentz factor of the blast wave) present even in the absence of an accelerated particle distribution and compare our results to bursts that cover this entire energy range. Particular emphasis is given on the emission at the GLAST energy range both in the prompt and the afterglow stages of the burst.

  7. Thermal infrared emissivity spectrum and its characteristics of crude oil slick covered seawater.

    Science.gov (United States)

    Xiong, Pan; Gu, Xing-Fai; Yu, Taol; Meng, Qing-Yan; Li, Jia-Guoi; Shi, Ji-xiang; Cheng, Yang; Wang, Liang; Liu, Wen-Song; Liu, Qi-Yuei; Zhao, Li-Min

    2014-11-01

    Detecting oil slick covered seawater surface using the thermal infrared remote sensing technology exists the advantages such as: oil spill detection with thermal infrared spectrum can be performed in the nighttime which is superior to visible spectrum, the thermal infrared spectrum is superior to detect the radiation characteristics of both the oil slick and the seawater compared to the mid-wavelength infrared spectrum and which have great potential to detect the oil slick thickness. And the emissivity is the ratio of the radiation of an object at a given temperature in normal range of the temperature (260-320 K) and the blackbody radiation under the same temperature , the emissivity of an object is unrelated to the temperature, but only is dependent with the wavelength and material properties. Using the seawater taken from Bohai Bay and crude oil taken from Gudao oil production plant of Shengli Oilfield in Dongying city of Shandong Province, an experiment was designed to study the characteristics and mechanism of thermal infrared emissivity spectrum of artificial crude oil slick covered seawater surface with its thickness. During the experiment, crude oil was continuously dropped into the seawater to generate artificial oil slick with different thicknesses. By adding each drop of crude oil, we measured the reflectivity of the oil slick in the thermal infrared spectrum with the Fourier transform infrared spectrometer (102F) and then calculated its thermal infrared emissivity. The results show that the thermal infrared emissivity of oil slick changes significantly with its thickness when oil slick is relatively thin (20-120 μm), which provides an effective means for detecting the existence of offshore thin oil slick In the spectrum ranges from 8 to 10 μm and from 13. 2 to 14 μm, there is a steady emissivity difference between the seawater and thin oil slick with thickness of 20 μm. The emissivity of oil slick changes marginally with oil slick thickness and

  8. Spectrum of the Anomalous Microwave Emission in the North Celestial Pole with WMAP 7-Year data

    CERN Document Server

    Bonaldi, Anna; 10.1155/2012/853927

    2013-01-01

    We estimate the frequency spectrum of the diffuse anomalous microwave emission (AME) on the North Celestial Pole (NCP) region of the sky with the Correlated Component Analysis (CCA) component separation method applied to WMAP 7-yr data. The NCP is a suitable region for this analysis because the AME is weakly contaminated by synchrotron and free-free emission. By modeling the AME component as a peaked spectrum we estimate the peak frequency to be $21.7\\pm0.8$\\,GHz, in agreement with previous analyses which favored $\

  9. Silicate Emission in the Spitzer IRS spectrum of FSC 10214+4724

    CERN Document Server

    Teplitz, H I; Charmandaris, V; Eisenhardt, P R M; Hao, L; Herter, T; Higdon, S; Houck, J R; Lacy, M; Lawrence, C R; Marshall, J A; Soifer, B T; Spoon, H; Wu, Y

    2006-01-01

    We present the first MIR spectrum of the z=2.2856 ultraluminous, infrared galaxy FSC 10214+4724, obtained with the Infrared Spectrograph onboard the Spitzer Space Telescope. The spectrum spans a rest wavelength range of 2.3-11.5 microns, covering a number of key diagnostic emission and absorption features. The most prominent feature in the IRS spectrum is the silicate emission at rest-frame 10 microns. We also detect an unresolved emission line at a rest wavelength of 7.65 microns which we identify with [NeVI], and a slightly resolved feature at 5.6 microns identified as a blend of [Mg VII] and [Mg V]. There are no strong PAH emission features in the FSC 10214+4724 spectrum. We place a limit of 0.1 micron on the equivalent width of 6.2 micron PAH emission but see no evidence of a corresponding 7.7 micron feature. Semi-empirical fits to the spectral energy distribution suggest about 45% of the bolometric luminosity arises from cold 50 K dust, half arises from warm (190 K) dust, and the remainder, 5%, originate...

  10. Structure dependent luminescence characterization of green-yellow emitting Sr{sub 2}SiO{sub 4}:Eu{sup 2+} phosphors for near UV LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Han, J.K. [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); Hannah, M.E.; Piquette, A. [Central Research, OSRAM SYLVANIA, 71 Cherry Hill Drive Beverly, MA 01915 (United States); Hirata, G.A. [Centro de Nanociencias y Nanotecnolgia, Universidad Nacional Autonoma de Mexico, Km. 107 Carretera Tijuana-Ensenada Apdo, Ensenada, MX CP 22860 (Mexico); Talbot, J.B. [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); Mishra, K.C. [Central Research, OSRAM SYLVANIA, 71 Cherry Hill Drive Beverly, MA 01915 (United States); McKittrick, J., E-mail: jmckittrick@ucsd.edu [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States)

    2012-01-15

    This paper reports on the luminescence properties of mixtures of {alpha}- and {beta}-(Sr{sub 0.97}Eu{sub 0.03}){sub 2}SiO{sub 4} phosphors. These phosphors were prepared by 3 different synthesis techniques: a modified sol-gel/Pechini method, a co-precipitation method and a combustion method. The structural and optical properties of these phosphors were compared to those of solid state synthesized powders. The emission spectra consist of a weak broad blue band centered near 460 nm and a strong broad green-yellow band centered between 543 and 573 nm depending on the crystal structure. The green-yellow emission peak blue-shifts as the amount of {beta} phase increases and the photoluminescence emission intensity and quantum efficiency of the mixed phase powders is greater than those of predominant {alpha}-phase powders when excited between 370 and 410 nm. Thus, (Sr{sub 1-x}Eu{sub x}){sub 2}SiO{sub 4} with larger proportion of the {beta} phase are more promising candidates than single {alpha}-phase powders for use as a green-yellow emitting phosphor for near UV LED applications. Finally the phosphors prepared by the sol-gel/Pechini method, which have larger amount of {beta} phase, have a higher emission intensity and quantum efficiency than those prepared by co-precipitation or combustion synthesis. - Highlights: > Mixtures of {alpha}- and {beta}-Sr{sub 2}SiO{sub 4}:Eu{sup 2+} phosphors were prepared by 3 different synthesis methods. > Emission peak blue-shifts as the amount of {beta} phase increases. > Emission intensity and QE of the {alpha}+{beta} powders are greater than those of single {alpha} phase. > Phosphors prepared by sol-gel/Pechini have the highest emission intensity and QE.

  11. A broadband cavity-enhanced spectrometer for measuring the extinction of aerosols at blue and near-UV wavelengths

    Science.gov (United States)

    Venables, Dean; Fullam, Donovan; Hoa Le, Phuoc; Chen, Jun; Böge, Olaf; Herrmann, Hartmut

    2016-04-01

    We describe a new broadband cavity-enhanced absorption spectrometer for sensitive extinction measurements of aerosols. The instrument is distinguished by its broad and continuous spectral coverage from the near-UV to blue wavelengths (ca. 320 to 450 nm). The short wavelength region has been little explored compared to visible wavelengths, but is important because (1) brown carbon (BrC) absorbs strongly in this wavelength region, and (2) absorption of near-UV radiation in the atmosphere alters the photolysis rate of the key atmospheric species O3, NO2, and HONO, with implications for air quality and atmospheric oxidation capacity. The instrument performance and the effect of a switchable in-line filter are characterised. Early results using the instrument in the TROPOS atmospheric simulation chamber are presented. These experiments include studies of secondary organic aerosol formation (SOA), and biomass burning experiments of rice and wheat straw, followed by experiments simulating particle aging under daytime and nighttime conditions.

  12. Phosphors for near UV-Emitting LED's for Efficacious Generation of White Light

    Energy Technology Data Exchange (ETDEWEB)

    McKittrick, Joanna

    2013-09-30

    1) We studied phosphors for near-UV (nUV) LED application as an alternative to blue LEDs currently being used in SSL systems. We have shown that nUV light sources could be very efficient at high current and will have significantly less binning at both the chip and phosphor levels. We identified phosphor blends that could yield 4100K lamps with a CRI of approximately 80 and LPWnUV,opt equal to 179 for the best performing phosphor blend. Considering the fact that the lamps were not optimized for light coupling, the results are quite impressive. The main bottleneck is an optimum blue phosphor with a peak near 440 nm with a full width half maximum of about 25 nm and a quantum efficiency of >95%. Unfortunately, that may be a very difficult task when we want to excite a phosphor at ~400 nm with a very small margin for Stokes shift. Another way is to have all the phosphors in the blend having the excitation peak at 400 nm or slightly shorter wavelength. This could lead to a white light source with no body color and optimum efficacy due to no self-absorption effects by phosphors in the blend. This is even harder than finding an ideal blue phosphor, but not necessarily impossible. 2) With the phosphor blends identified, light sources using nUV LEDs at high current could be designed with comparable efficacy to those using blue LEDs. It will allow us to design light sources with multiple wattages using the same chips and phosphor blends simply by varying the input current. In the case of blue LEDs, this is not currently possible because varying the current will lower the efficacy at high current and alter the color point. With improvement of phosphor blends, control over CRI could improve. Less binning at the chip level and also at the phosphor blend level could reduce the cost of SSL light sources. 3) This study provided a deeper understanding of phosphor characteristics needed for LEDs in general and nUV LEDs in particular. Two students received Ph.D. degrees and three

  13. A Compact, Tunable Near-UV Source for Quantitative Microgravity Combustion Diagnostics

    Science.gov (United States)

    Peterson, K. A.; Oh, D. B.

    1999-01-01

    There is a need for improved optical diagnostic methods for use in microgravity combustion research. Spectroscopic methods with fast time response that can provide absolute concentrations and concentration profiles of important chemical species in flames are needed to facilitate the understanding of combustion kinetics in microgravity. Although a variety of sophisticated laser-based diagnostics (such as planar laser induced fluorescence, degenerate four wave mixing and coherent Raman methods) have been applied to the study of combustion in laboratory flames, the instrumentation associated with these methods is not well suited to microgravity drop tower or space station platforms. Important attributes of diagnostic systems for such applications include compact size, low power consumption, ruggedness, and reliability. We describe a diode laser-based near-UV source designed with the constraints of microgravity research in mind. Coherent light near 420 nm is generated by frequency doubling in a nonlinear crystal. This light source is single mode with a very narrow bandwidth suitable for gas phase diagnostics, can be tuned over several 1/cm and can be wavelength modulated at up to MHz frequencies. We demonstrate the usefulness of this source for combustion diagnostics by measuring CH radical concentration profiles in an atmospheric pressure laboratory flame. The radical concentrations are measured using wavelength modulation spectroscopy (WMS) to obtain the line-of-sight integrated absorption for different paths through the flame. Laser induced fluorescence (LIF) measurements are also demonstrated with this instrument, showing the feasibility of simultaneous WMS absorption and LIF measurements with the same light source. LIF detection perpendicular to the laser beam can be used to map relative species densities along the line-of-sight while the integrated absorption available through WMS provides a mathematical constraint on the extraction of quantitative information

  14. Lanthanides post-functionalized indium metal-organic frameworks (MOFs) for luminescence tuning, polymer film preparation and near-UV white LED assembly.

    Science.gov (United States)

    Wu, Jing-Xing; Yan, Bing

    2016-11-22

    A class of hybrid materials based on indium 2,2'-bipyridine-5,5'-dicarboxylate metal-organic frameworks, In(OH)bpydc, was synthesized by postsynthetic introduction with lanthanide ions (Eu(3+), Tb(3+) and Sm(3+)). The structure, thermal stability, morphology and more detailed information about these materials were characterized by XRD, DSC, BET, FTIR, SEM and so forth. The further study of luminescent properties in detail showed that these compounds possess characteristic emission, and the In-MOF-Eu maintains different colors of light from blue-green to red under different excitation wavelengths (excited at 400 nm to 320 nm), which includes the near-white light region (the color coordinates are X = 0.34, Y = 0.36). It is a remarkable fact that the trend of ligand-central emission is opposite to that of the characteristic emission of Eu(3+). Moreover, a kind of thin film and assembled white light near-UV LED based on the optically lanthanide-functionalized MOFs was prepared in order to extend their potential applications; both of them lead to desirable white light (X = 0.34, Y = 0.36; X = 0.35, Y = 0.37). In addition, the matrix does not affect the white luminescence.

  15. Optical emission spectrum of filamentary nanosecond surface dielectric barrier discharge

    Science.gov (United States)

    Shcherbanev, S. A.; Khomenko, A. Yu; Stepanyan, S. A.; Popov, N. A.; Starikovskaia, S. M.

    2017-02-01

    Streamer-to-filament transition is a general feature of high pressure high voltage (HV) nanosecond surface dielectric barrier discharges. The transition was studied experimentally using time- and space-resolved optical emission in UV and visible parts of spectra. The discharge was initiated by HV pulses 20 ns in duration and 2 ns rise time, positive or negative polarity, 20-60 kV in amplitude on the HV electrode. The experiments were carried out in a single-shot regime at initial pressures P  >  3 bar and ambient initial temperature in air, N2, H2:N2 and O2:Ar mixtures. It was shown that the transition to filamentary mode is accompanied by the appearance of intense continuous radiation and broad atomic lines. Electron density calculated from line broadening is characterized by high absolute values and long decay in the afterglow. The possible reasons for the continuous spectra were analyzed.

  16. Photolysis quantum yield measurements in the near-UV; a critical analysis of 1-(2-nitrophenyl)ethyl photochemistry.

    Science.gov (United States)

    Corrie, John E T; Kaplan, Jack H; Forbush, Biff; Ogden, David C; Trentham, David R

    2016-05-11

    The photolysis quantum yield, Qp, of 1-(2-nitrophenyl)ethyl phosphate (caged Pi) measured in the near-UV (342 nm peak with 60 nm half-bandwidth) is 0.53 and is based on results reported in 1978 (Biochemistry, 17, 1929-1935). This article amplifies methodology for determining that Qp in view of different recent estimates. Some general principles together with other examples relating to measurement of Qp values are discussed together with their relevance to biological research.

  17. GMRT 150 MHz follow up of diffuse steep spectrum radio emission in galaxy clusters

    CERN Document Server

    Macario, G; Dallacasa, D; Giacintucci, S; Brunetti, G; Cassano, R; Ishwara-Chandra, C H; Athreya, R

    2011-01-01

    It has been recently found that a few galaxy clusters host diffuse radio halo emission with very steep synchrotron spectra ($\\alpha$ > 1.6), which may be classified as Ultra Steep Spectrum Radio Halos (USSRHs). USSRHs are expected in the turbulence re-acceleration model for the origin of cluster radio halos, and are best discovered and studied at low frequencies. We performed GMRT follow up observations of three galaxy clusters at 150MHz, selected from the GMRT radio halo survey, which are known to host an USSRH or candidate very steep spectrum diffuse emission. This project is aimed to characterize the low frequency spectrum of USSRHs for a detailed study of their origin and connection with cluster mergers. We present preliminary results at 150 MHz of the cluster A697.

  18. Repair and actio spectrum of oxygen-independent lethality of near uv light on Haemophilus influenzae and lack of mutation

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera-Juarez, E.; Setlow, J.K.

    1980-01-01

    Haemophilus influenzae has been inactivated anaerobically at 313, 334, 365, and 405 nm, and exhibits the greatest sensitivity at 334 nm. The rec1 and uvr1 mutants show the greatest increase in sensitivity over the wild-type at 313 nm, but differences could be seen also at the other wavelengths. Anaerobic irradiation is less effective for killing at all the wavelengths than irradiation under aerobic conditions, but the greatest difference was observed at 365 nm. No induced mutation was seen as a result of anaerobic irradiation at 334 nm, although purified transforming DNA can be mutated at this wavelength.

  19. Spontaneous emission spectrum of a four-level atom in a double-band photonic crystal

    Institute of Scientific and Technical Information of China (English)

    Wang Jian; Yang Dong; Zhang Han-Zhang

    2005-01-01

    The spontaneous emission spectrum from a four-level atom in a double-band photonic crystal has been investigated.We use the model which assumes three atomic transitions. One of the transitions interacts with the free vacuum modes,and the other two transitions couple to the modes of the isotropic photonic band gap (PBG), the anisotropic PBG and another free vacuum. The effects of the fine structure of the lower levels on the spontaneous emission spectrum of an atom are investigated in detail in the three cases. New features of four (two) transparencies with two (one) spontaneous emission peaks, resulting from the fine structure of the lower levels of an atom, are predicted in the case of isotropic PBG modes.

  20. Orbitally modulated photoexcited Si I emission in the eclipsing composite-spectrum binary ζ Aurigae

    Science.gov (United States)

    Harper, G. M.; Griffin, R. E. M.; Bennett, P. D.; O'Riain, N.

    2016-02-01

    We examine the little-known phenomenon of orbitally modulated Si I emission at λ 3905.523 Å and λ 4102.936 Å in composite-spectrum binaries, with specific reference to ζ Aurigae (K4 Ib + B5 V). The emission is detected in the isolated spectrum of the B-type dwarf secondary, and while λ 4102 Å is heavily blended with Hδ, λ 3905 Å falls in the B-star's featureless continuum. The narrowness of the emission (vturb ≃ 6 km s-1) demonstrates that it originates in the upper photosphere or deep chromosphere of the K star primary. We propose that photoexcitation by the hot star's UV continuum, followed by recombination and cascades, leads to resonant scattering and subsequent pumping of lower opacity transitions in the singlet and triplet systems of Si I. This process channels the UV continuum into select narrow emission lines. We have also identified weaker photoexcited emission of Fe II at λ 3938.289 Å. The strengths, positions, and widths of the λ 3905 Å emission line vary with orbital phase owing to changes in the dilution of the irradiating flux and in the geometrical aspect of the irradiated hemisphere. Utilizing the inherent spatial resolution provided by the illuminated patch, and assuming that the K star is spherical with isotropic emission, yields vsin i ˜ 5.7 km s-1. Evidence of tidal distortion was deduced from the timing of the rapidly rising phase of the emission just after periastron. Increasing the diagnostic potential requires radiative transfer modelling of the formation and centre-to-limb variation of the emission.

  1. 153 MHz GMRT follow-up of steep-spectrum diffuse emission in galaxy clusters

    CERN Document Server

    Macario, G; Intema, H T; Dallacasa, D; Brunetti, G; Cassano, R; Giacintucci, S; Ferrari, C; Ishwara-Chandra, C H; Athreya, R

    2013-01-01

    In this paper we present new high sensitivity 153 MHz Giant Meterwave Radio Telescope follow-up observations of the diffuse steep spectrum cluster radio sources in the galaxy clusters Abell 521, Abell 697, Abell 1682. Abell 521 hosts a relic, and together with Abell 697 it also hosts a giant very steep spectrum radio halo. Abell 1682 is a more complex system with candidate steep spectrum diffuse emission. We imaged the diffuse radio emission in these clusters at 153 MHz, and provided flux density measurements of all the sources at this frequency. Our new flux density measurements, coupled with the existing data at higher frequencies, allow us to study the total spectrum of the halos and relic over at least one order of magnitude in frequency. Our images confirm the presence of a very steep "diffuse component" in Abell 1682. We found that the spectrum of the relic in Abell 521 can be fitted by a single power-law with $\\alpha=1.45\\pm0.02$ from 153 MHz to 5 GHz. Moreover, we confirm that the halos in Abell 521 a...

  2. Novel red phosphors LaBSiO5 co-doped with Eu3+, Al3+ for near-UV light-emitting diodes

    Science.gov (United States)

    Wang, Zhengliang; Cheng, Ping; Liu, Yong; Zhou, Yayun; Zhou, Qiang; Guo, Junmin

    2014-11-01

    Red-emitting phosphors LaBSiO5:Eu3+ and LaBSiO5:Eu3+, Al3+ were synthesized by the conventional solid state method at 1100 °C. The structure and luminescent properties of these phosphors are investigated. LaBSiO5:Eu3+ and LaBSiO5:Eu3+, Al3+ could be efficiently excited by near ultraviolet light with the strongest excitation peak at 395 nm. The main emission peak is located at around 616 nm, which corresponds to the transition of 5D0 → 7F2 of Eu3+ ions. The emission intensity of LaBSiO5:Eu3+ was enhanced by introducing Al3+ ions. Compared with Y2O2S:0.05Eu3+, the sample La0.70B0.75SiO5:0.30Eu3+, 0.25Al3+ shares the intense red emission, and its emission intensity is about 3.8 times as strong as that of Y2O2S:0.05Eu3+ under 395 nm light excitation. Bright red light can be observed from the red LED based on La0.70B0.75SiO5:0.30Eu3+, 0.25Al3+, hence La0.70B0.75SiO5:0.30Eu3+, 0.25Al3+ maybe find application on near-UV InGaN-based white LEDs.

  3. In Situ Measurement of Alkali Metals in an MSW Incinerator Using a Spontaneous Emission Spectrum

    Directory of Open Access Journals (Sweden)

    Weijie Yan

    2017-03-01

    Full Text Available This paper presents experimental investigations of the in situ diagnosis of the alkali metals in the municipal solid waste (MSW flame of an industrial grade incinerator using flame emission spectroscopy. The spectral radiation intensities of the MSW flame were obtained using a spectrometer. A linear polynomial fitting method is proposed to uncouple the continuous spectrum and the characteristic line. Based on spectra processing and a non-gray emissivity model, the flame temperature, emissivity, and intensities of the emission of alkali metals were calculated by means of measuring the spectral radiation intensities of the MSW flame. Experimental results indicate that the MSW flame contains alkali metals, including Na, K, and even Rb, and it demonstrates non-gray characteristics in a wavelength range from 500 nm to 900 nm. Peak intensities of the emission of the alkali metals were found to increase when the primary air was high, and the measured temperature varied in the same way as the primary air. The temperature and peak intensities of the lines of emission of the alkali metals may be used to adjust the primary airflow and to manage the feeding of the MSW to control the alkali metals in the MSW flame. It was found that the peak intensity of the K emission line had a linear relationship with the peak intensity of the Na emission line; this correlation may be attributed to their similar physicochemical characteristics in the MSW. The variation trend of the emissivity of the MSW flame and the oxygen content in the flue gas were almost opposite because the increased oxygen content suppressed soot formation and decreased soot emissivity. These results prove that the flame emission spectroscopy technique is feasible for monitoring combustion in the MSW incinerator in situ.

  4. Genetic control of prophage induction in Haemophilus influenzae after exposure to psoralen plus near-uv light

    Energy Technology Data Exchange (ETDEWEB)

    George, M.; Notani, N.K.

    1980-09-01

    Prophage S2 could be induced by psoralen plus near-uv light (PNUV) from a wild-type strain of Haemophilus influenzae, from uv light-sensitive strains uvr-1 and uvr-2, and PNUV-sensitive strains PSO1 and PSO7, but not from a recombination-deficient strain, rec-1. The levels of prophage induction were comparable in the wild type and an ATP-dependent DNase-deficient strain, KW31, even though the PNUV-induced degradation in the latter strain was considerably lower. Prophage induction could be observed even with chloramphenicol present before, during, and 30 min after PNUV treatment.

  5. OMI/Aura Near UV Aerosol Optical Depth and Single Scattering Albedo 1-orbit L2 Swath 13x24 km V003 NRT

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI/Aura level-2 near UV Aerosol data product 'OMAERUV', recently re-processed using an enhanced algorithm, is now released (April 2012) to the public. The data...

  6. Bayesian modelling of the emission spectrum of the JET Li-BES system

    CERN Document Server

    Kwak, Sehyun; Brix, M; Ghim, Y -c; Contributors, JET

    2015-01-01

    A Bayesian model of the emission spectrum of the JET lithium beam has been developed to infer the intensity of the Li I (2p-2s) line radiation and associated uncertainties. The detected spectrum for each channel of the lithium beam emission spectroscopy (Li-BES) system is here modelled by a single Li line modified by an instrumental function, Bremsstrahlung background, instrumental offset, and interference filter curve. Both the instrumental function and the interference filter curve are modelled with non-parametric Gaussian processes. All free parameters of the model, the intensities of the Li line, Bremsstrahlung background, and instrumental offset, are inferred using Bayesian probability theory with a Gaussian likelihood for photon statistics and electronic background noise. The prior distributions of the free parameters are chosen as Gaussians. Given these assumptions, the intensity of the Li line and corresponding uncertainties are analytically available using a Bayesian linear inversion technique. The p...

  7. Time variation of emission lines structure in the spectrum of HR Delfini

    Energy Technology Data Exchange (ETDEWEB)

    Babaev, M.B. (AN Azerbajdzhanskoj SSR, Baku. Shemakhinskaya Astrofizicheskaya Observatoriya)

    1983-04-01

    It is found that H..beta.., HeII lambda4686 and (OIII)lambdalambda4959, 5007 emission lines in the spectrum of nova HR Del had in 1981 four-component structure, as they did earlier. A comparison with 1968-1978 spectra reveals the changes in relative intensities of the internal and external components of these lines. It is concluded that time variations of physical conditions occur in some condensation in the envelope of HR Del.

  8. Gamma-ray emission spectrum from thermonuclear fusion reactions without intrinsic broadening

    DEFF Research Database (Denmark)

    Nocente, M.; Källne, J.; Salewski, Mirko

    2015-01-01

    First principle calculations of the gamma-ray energy spectrum arising from thermonuclear reactions without intrinsic broadening in fusion plasmas are presented, extending the theoretical framework needed to interpret measurements up to the accuracy level enabled by modern high resolution instrume......First principle calculations of the gamma-ray energy spectrum arising from thermonuclear reactions without intrinsic broadening in fusion plasmas are presented, extending the theoretical framework needed to interpret measurements up to the accuracy level enabled by modern high resolution...... information that can be extracted from the gamma-ray emission spectrum of fusion reactions without intrinsic broadening and are of relevance for applications to high performance plasmas of present and next generation devices....

  9. Near-UV stress in salmonella typhimurium: 4-thiouridine in tRNA, ppGpp, and ApppGpp as components of an adaptive response

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, G.F.; Baker, J.C.; Ames, B.N.

    1988-05-01

    We have examined the role of 4-thiouridine in the responses of Salmonella typhimurium to near-UV irradiation. Mutants lacking 4-thiouridine (nuv) and mutants defective in the synthesis of ppGpp (guanosine 5'-diphosphate-3'-diphosphate) (relA) were found to be sensitive to killing by near-UV. Near-UV induced the synthesis of a set of proteins that were not induced in the nuv mutant. Some of these proteins were identified as oxidative defense proteins, and others were identified as ppGpp-inducible proteins. Over 100-fold increases in ApppGpp (adenoisine 5', 5'''-triphosphoguanosine-3'''-diphosphate, the adenylylated form of ppGpp) were observed in wild-type cells after near-UV irradiation but not in the 4-thiouridine-deficient mutant. These data support a model in which ppGpp and ApppGpp, a dinucleotide proposed to be synthesized by tRNA-aminoacyl synthetases as a response to the cross-linking of 4-thiouridine in tRNA by near-UV, induce the synthesis of proteins necessary for resistance to near-UV irradiation.

  10. BPO4@B2O3 and (BPO4@B2O3):Eu3+: The novel single-emitting-component phosphors for near UV-white LEDs

    Science.gov (United States)

    Cao, Xiyu; Liu, Wei; Jiang, Yu; Cao, Lixin; Su, Ge; Gao, Rongjie

    2016-08-01

    Nowadays much effort has been devoted to exploring novel luminescent materials with low-cost, high stability and excellent luminescent properties. In this paper, a new kind of luminescent material BPO4@B2O3 was prepared by using a facile method. The as-obtained samples contain numerous BPO4 nanoparticles enclosed by amorphous and crystalline B2O3 homogeneously, which exhibits a broad emission band ranging from 380 to 700 nm under near-UV irradiation. More importantly, it is worth noting that the BPO4@B2O3 phosphor exhibits the excellent thermal quenching property, which endows it with a promising prospect as phosphors for high power white LEDs. To further promote its application as white light phosphors, Eu3+ ions were doped into the BPO4@B2O3 samples and prepared the (BPO4@B2O3):Eu3+ phosphors with chromaticity coordinates (0.3022, 0.3122). The corresponding packaging of LEDs indicates that both BPO4@B2O3 and (BPO4@B2O3):Eu3+ can be considered as the promising phosphors for WLEDs.

  11. Wide and deep near-UV (360nm) galaxy counts and the extragalactic background light with the Large Binocular Camera

    CERN Document Server

    Grazian, A; Giallongo, E; Gallozzi, S; Fontanot, F; Fontana, A; Testa, V; Ragazzoni, R; Baruffolo, A; Beccari, G; Diolaiti, E; Di Paola, A; Farinato, J; Gasparo, F; Gentile, G; Green, R; Hill, J; Kuhn, O; Pasian, F; Pedichini, F; Radovich, M; Smareglia, R; Speziali, R; Thompson, D; Wagner, R M

    2009-01-01

    Deep multicolour surveys are the main tool to explore the formation and evolution of the faint galaxies which are beyond the spectroscopic limit with the present technology. The photometric properties of these faint galaxies are usually compared with current renditions of semianalytical models to provide constraints on the fundamental physical processes involved in galaxy formation and evolution, namely the mass assembly and the star formation. Galaxy counts over large sky areas in the near-UV band are important because they are difficult to obtain given the low efficiency of near-UV instrumentation, even at 8m class telescopes. A large instrumental field of view helps in minimizing the biases due to the cosmic variance. We have obtained deep images in the 360nm U band provided by the blue channel of the Large Binocular Camera at the prime focus of the Large Binocular Telescope. We have derived over an area of ~0.4 sq. deg. the galaxy number counts down to U=27 in the Vega system (corresponding to U=27.86 in ...

  12. Steep-Spectrum Radio Emission from the Low-Mass Active Galactic Nucleus GH 10

    CERN Document Server

    Wróbel, J M; Ho, L C; Ulvestad, J S

    2008-01-01

    GH 10 is a broad-lined active galactic nucleus (AGN) energized by a black hole of mass 800,000 Solar masses. It was the only object detected by Greene et al. in their Very Large Array (VLA) survey of 19 low-mass AGNs discovered by Greene & Ho. New VLA imaging at 1.4, 4.9, and 8.5 GHz reveals that GH 10's emission has an extent of less than 320 pc, has an optically-thin synchrotron spectrum with a spectral index -0.76+/-0.05, is less than 11 percent linearly polarized, and is steady - although poorly sampled - on timescales of weeks and years. Circumnuclear star formation cannot dominate the radio emission, because the high inferred star formation rate, 18 Solar masses per year, is inconsistent with the rate of less than 2 Solar masses per year derived from narrow Halpha and [OII] 3727 emission. Instead, the radio emission must be mainly energized by the low-mass black hole. GH 10's radio properties match those of the steep-spectrum cores of Palomar Seyfert galaxies, suggesting that, like those Seyferts, t...

  13. [Investigation on the gas temperature of a plasma jet at atmospheric pressure by emission spectrum].

    Science.gov (United States)

    Li, Xue-chen; Yuan, Ning; Jia, Peng-ying; Niu, Dong-ying

    2010-11-01

    A plasma jet of a dielectric barrier discharge in coaxial electrode was used to produce plasma plume in atmospheric pressure argon. Spatially and temporally resolved measurement was carried out by photomultiplier tubes. The light emission signals both from the dielectric barrier discharge and from the plasma plume were analyzed. Furthermore, emission spectrum from the plasma plume was collected by high-resolution optical spectrometer. The emission spectra of OH (A 2sigma + --> X2 II, 307.7-308.9 nm) and the first negative band of N2+ (B2 sigma u+ --> X2 IIg+, 390-391.6 nm) were used to estimate the rotational temperature of the plasma plume by fitting the experimental spectra to the simulated spectra. The rotational temperature obtained is about 443 K by fitting the emission spectrum from the OH, and that from the first negative band of N2+ is about 450 K. The rotational temperatures obtained by the two method are consistent within 5% error band. The gas temperature of the plasma plume at atmospheric pressure was obtained because rotational temperature equals to gas temperature approximately in gas discharge at atmospheric pressure. Results show that gas temperature increases with increasing the applied voltage.

  14. Nitride superluminescent diodes with broadened emission spectrum fabricated using laterally patterned substrate.

    Science.gov (United States)

    Kafar, A; Stanczyk, S; Sarzynski, M; Grzanka, S; Goss, J; Targowski, G; Nowakowska-Siwinska, A; Suski, T; Perlin, P

    2016-05-01

    We demonstrate InGaN/GaN superluminescent diodes with broadened emission spectra fabricated on surface-shaped bulk GaN (0001) substrates. The patterning changes the local vicinal angle linearly along the device waveguide, which results in an indium incorporation profile in InGaN quantum wells. The structure was investigated by microphotoluminescence mapping, showing a shift of central emission wavelength from 413 nm to 430 nm. Spectral full width at half maximum of processed superluminescent diodes is equal to 6.1 nm, while the reference chips show 3.4 nm. This approach may open the path for using nitride devices in applications requiring broad emission spectrum and high beam quality, such as optical coherence tomography.

  15. Continuous Emission Spectrum Measurement for Electron Temperature Determination in Low-Temperature Collisional Plasmas%Continuous Emission Spectrum Measurement for Electron Temperature Determination in Low-Temperature Collisional Plasmas

    Institute of Scientific and Technical Information of China (English)

    刘秋艳; 李弘; 陈志鹏; 谢锦林; 刘万东

    2011-01-01

    Continuous emission spectrum measurement is applied for the inconvenient diagnos- tics of low-temperature collisional plasmas. According to the physical mechanism of continuous emission, a simplified model is presented to analyze the spectrum in low temperature plasma. The validity of this model is discussed in a wide range of discharge parameters, including electron tem- perature and ionization degree. Through the simplified model, the continuous emission spectrum in a collisional argon internal inductively coupled plasma is experimentally measured to determine the electron temperature distribution for different gas pressures and radio-frequency powers. The inverse Abel transform is also applied for a better spatially resoluted results. Meanwhile, the result of the continuous emission spectrum measurement is compared to that of the electrostatic double probes, which indicates the effectiveness of this method.

  16. Spectrum

    DEFF Research Database (Denmark)

    Høgfeldt Hansen, Leif

    2016-01-01

    The publication functions as a proces description of the development and construction of an urban furniture SPECTRUM in the city of Gwangju, Republic of Korea. It is used as the cataloque for the exhibition of Spectrum.......The publication functions as a proces description of the development and construction of an urban furniture SPECTRUM in the city of Gwangju, Republic of Korea. It is used as the cataloque for the exhibition of Spectrum....

  17. Spectrum of the Anomalous Microwave Emission in the North Celestial Pole with WMAP 7-Year Data

    Directory of Open Access Journals (Sweden)

    Anna Bonaldi

    2012-01-01

    Full Text Available We estimate the frequency spectrum of the diffuse anomalous microwave emission (AME on the North Celestial Pole (NCP region of the sky with the Correlated Component Analysis (CCA component separation method applied to WMAP 7-yr data. The NCP is a suitable region for this analysis because the AME is weakly contaminated by synchrotron and free-free emission. By modeling the AME component as a peaked spectrum we estimate the peak frequency to be 21.7±0.8 GHz, in agreement with previous analyses which favored νp < 23 GHz. The ability of our method to correctly recover the position of the peak is verified through simulations. We compare the estimated AME spectrum with theoretical spinning dust models to constrain the hydrogen density nH. The best results are obtained with densities around 0.2–0.3 cm−3, typical of warm ionised medium (WIM to warm neutral medium (WNM conditions. The degeneracy with the gas temperature prevents an accurate determination of nH, especially for low hydrogen ionization fractions, where densities of a few cm−3 are also allowed.

  18. The Nuclear Region of Low Luminosity Flat Radio Spectrum Sources. II. Emission-Line Spectra

    CERN Document Server

    Gonçalves, A C

    2004-01-01

    We report on the spectroscopic study of 19 low luminosity Flat Radio Spectrum (LL FRS) sources selected from Marcha's et al. (1996) 200 mJy sample. In the optical, these objects are mainly dominated by the host galaxy starlight. After correcting the data for this effect, we obtain a new set of spectra clearly displaying weak emission lines; such features carry valuable information concerning the excitation mechanisms at work in the nuclear regions of LL FRS sources. We have used a special routine to model the spectra and assess the intensities and velocities of the emission lines; we have analyzed the results in terms of diagnostic diagrams. Our analysis shows that 79% of the studied objects harbour a Low Ionization Nuclear Emission-line Region (or LINER) whose contribution was swamped by the host galaxy starlight. The remaining objects display a higher ionization spectrum, more typical of Seyferts; due to the poor quality of the spectra, it was not possible to identify any possible large Balmer components. T...

  19. Bloated stars as agn broad line clouds the emission line spectrum

    CERN Document Server

    Alexander, T; Tal Alexander; Hagai Netzer

    1994-01-01

    The `Bloated Stars Scenario' proposes that AGN broad line emission originates in the winds or envelopes of bloated stars (BS). Its main advantage over BLR cloud models is the gravitational confinement of the gas and its major difficulty the large estimated number of BSs and resulting high mass loss rate. We calculate the emission line spectrum by a detailed numerical photoionization code for a wide range of wind structures and a detailed QSO nucleus model with L(ion)=7E45 erg/s, M(bh)=8E7 Mo. The size and boundary density of the BS wind are determined by various processes: Comptonization by the central continuum source, calculated self consistently, tidal disruption by the black hole and the limit set by the wind's finite mass. We find that the emission spectrum is mainly determined by the conditions at the boundary of the line emitting fraction of the wind rather than by its internal structure. Comptonization results in very high ionization parameters at the boundary which produces an excess of unobserved br...

  20. The 2 μm spectrum of the auroral emission in the polar regions of Jupiter

    Science.gov (United States)

    Kedziora-Chudczer, L.; Cotton, D. V.; Kedziora, D. J.; Bailey, J.

    2017-09-01

    We report observations of the high (R ∼ 18000) and medium (R ∼ 5900) resolution, near-infrared spectra of Jupiter's polar regions with the GNIRS instrument at the Gemini North telescope. The observations correspond to the area of main auroral oval in the South and the main spot of the Io footprint in the North. We detected and assigned 18 emission lines of the H3+ , 2ν2 → 0 overtone band in the region from 4800 to 4980 cm-1 and 5 additional lines in the extended low-resolution spectrum. We use our new modelling scheme, ATMOF to remove telluric absorption bands of CO2 that feature strongly in the 2 μm region. The H2 1-0 S(1), S(2) and S(3) emission lines are also detected in the observed spectral region. We found the rotational temperature and column density of H3+ emission at the peak intensity for both northern and southern auroral regions to be the same within the measurement errors (Trot ∼ 950K and N(H3+) ∼ 4.5× 1016 m-2). The estimates of Trot from H2 are consistent within much higher uncertainties with temperatures derived from H3+ emissions. We derived the profiles of the H3+ emissivity and ion density for both auroral regions providing the first such measurement for the emission associated with the main spot of the Io footprint. We also found a number of weaker lines in the high-resolution spectra that could be associated with emission from high excitation levels in neutral iron, which could be deposited in Jupiter's atmosphere as a result of meteor ablation.

  1. Synthesis and photoluminescence characteristics of (Y,Gd)BO3:RE (RE = Eu(3+), Ce(3+), Dy(3+) and Tb(3+)) phosphors for blue chip and near-UV white LEDs.

    Science.gov (United States)

    Rangari, V V; Singh, V; Dhoble, S J

    2016-03-01

    A series of Eu(3+)-, Ce(3+)-, Dy(3+)- and Tb(3+)-doped (Y,Gd)BO3 phosphors was synthesized by a solid-state diffusion method. X-Ray diffraction confirmed their hexagonal structure and the scanning electron microscopy results showed crystalline particles. The excitation spectra revealed that (Y,Gd)BO3 phosphors doped with Eu(3+), Ce(3+), Dy(3+) and Tb(3+) are effectively excited with near UV-light of 395 nm/blue light, 364, 351 and 314 nm, respectively. Photoluminescence spectra of Eu(3+)-, Ce(3+)- and Tb(3+)/Dy(3+)-doped phosphor showed intense emission of reddish orange, blue and white light, respectively. The phosphor Y0.60Gd0.38BO3:Ce0.02 showed CIE 1931 color coordinates of (0.158, 0.031) and better color purity compared with commercially available blue BAM:Eu(2+) phosphor. The phosphor (Y,Gd)BO3 doped with Eu(3+), Dy(3+) and Tb(3+) showed CIE 1931 color coordinates of (0.667, 0.332), (0.251, 0.299) and (0.333, 0.391) respectively. Significant photoluminescence characteristics of the prepared phosphors indicate that they might serve as potential candidates for blue chip and near-UV white light-emitting diode applications. Copyright © 2015 John Wiley & Sons, Ltd.

  2. Enhancement of near-UV GaN LED light extraction efficiency by GaN/sapphire template patterning

    Science.gov (United States)

    Ali, M.; Svensk, O.; Riuttanen, L.; Kruse, M.; Suihkonen, S.; Romanov, A. E.; Törmä, P. T.; Sopanen, M.; Lipsanen, H.; Odnoblyudov, M. A.; Bougrov, V. E.

    2012-08-01

    We present near-UV GaN light-emitting diodes (LEDs) grown on patterned GaN/sapphire templates with improved material quality and light extraction efficiency. Enhancement of light extraction efficiency is attributed to voids generated at the GaN/sapphire interface. The sidewall inclination angle of the voids can be controlled from nearly vertical (˜ 85°) to fully inclined (˜ 60°) by changing the initial patterning dimensions. Light extraction efficiency and material quality improve with a decreasing void sidewall angle. A 20% increase in the light output is observed at 20 mA of input current for LED structures with ˜60° inclined sidewall voids.

  3. A GIANO-TNG high resolution IR spectrum of the airglow emission

    CERN Document Server

    Oliva, E; Maiolino, R; Baffa, C; Biliotti, V; Bruno, P; Falcini, G; Gavriousev, V; Ghinassi, F; Giani, E; Gonzalez, M; Leone, F; Lodi, M; Massi, F; Montegriffo, P; Mochi, I; Pedani, M; Rossetti, E; Scuderi, S; Sozzi, M; Tozzi, A; Valenti, E

    2013-01-01

    A flux-calibrated high resolution spectrum of the airglow emission is a practical lambda-calibration reference for astronomical spectral observations. It is also useful for constraining the molecular parameters of the OH molecule and the physical conditions in the upper mesosphere. methods: We use the data collected during the first technical commissioning of the GIANO spectrograph at the Telescopio Nazionale Galileo (TNG). The high resolution (R~50,000) spectrum simultaneously covers the 0.95-2.4 micron wavelength range. Relative flux calibration is achieved by the simultaneous observation of spectrophotometric standard star. results: We derive a list of improved positions and intensities of OH infrared lines. The list includes Lambda-split doublets many of which are spectrally resolved. Compared to previous works, the new results correct errors in the wavelengths of the Q-branch transitions. The relative fluxes of OH lines from different vibrational bands show remarkable deviations from theoretical predicti...

  4. Constraining the neutrino emission of gravitationally lensed Flat-Spectrum Radio Quasars with ANTARES data

    Energy Technology Data Exchange (ETDEWEB)

    Adrián-Martínez, S.; Ardid, M.; Bou-Cabo, M. [Institut d' Investigació per a la Gestió Integrada de les Zones Costaneres (IGIC), Universitat Politècnica de València, C/ Paranimf 1, Gandia, 46730 Spain (Spain); Albert, A. [GRPHE - Institut universitaire de technologie de Colmar, 34 rue du Grillenbreit BP 50568, Colmar, 68008 France (France); André, M. [Technical University of Catalonia, Laboratory of Applied Bioacoustics, Rambla Exposició, Vilanova i la Geltrú, Barcelona, 08800 Spain (Spain); Anton, G. [Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, Erlangen, 91058 Germany (Germany); Aubert, J.-J.; Bertin, V.; Brunner, J.; Busto, J. [Aix Marseille Université, CNRS/IN2P3, CPPM UMR 7346, Marseille, 13288 France (France); Baret, B. [APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu, Observatoire de Paris, Sorbonne Paris Cité, 10, rue Alice Domon et Léonie Duquet, Paris Cedex 13, F-75205 France (France); Barrios-Martí, J. [IFIC - Instituto de Física Corpuscular, Edificios Investigación de Paterna, CSIC - Universitat de València, Apdo de Correos 22085, Valencia, 46071 Spain (Spain); Basa, S. [LAM - Laboratoire d' Astrophysique de Marseille, Pôle de l' Étoile Site de Château-Gombert, rue Frédéric Joliot-Curie 38, Marseille Cedex 13, 13388 France (France); Biagi, S. [INFN - Sezione di Bologna, Viale Berti-Pichat 6/2, Bologna, 40127 Italy (Italy); Bogazzi, C.; Bormuth, R.; Bouwhuis, M.C.; Bruijn, R. [Nikhef, Science Park 105, Amsterdam, 1098XG The Netherlands (Netherlands); Capone, A. [INFN -Sezione di Roma, P.le Aldo Moro 2, Roma, 00185 Italy (Italy); Caramete, L., E-mail: antares.spokesperson@in2p3.fr [Institute for Space Sciences, Bucharest, Măgurele, R-77125 Romania (Romania); and others

    2014-11-01

    This paper proposes to exploit gravitational lensing effects to improve the sensitivity of neutrino telescopes to the intrinsic neutrino emission of distant blazar populations. This strategy is illustrated with a search for cosmic neutrinos in the direction of four distant and gravitationally lensed Flat-Spectrum Radio Quasars. The magnification factor is estimated for each system assuming a singular isothermal profile for the lens. Based on data collected from 2007 to 2012 by the ANTARES neutrino telescope, the strongest constraint is obtained from the lensed quasar B0218+357, providing a limit on the total neutrino luminosity of this source of 1.08× 10{sup 46} erg s{sup -1}. This limit is about one order of magnitude lower than those previously obtained in the ANTARES standard point source searches with non-lensed Flat-Spectrum Radio Quasars.

  5. A ten-year global record of absorbing aerosols above clouds from OMI's near-UV observations

    Science.gov (United States)

    Jethva, Hiren; Torrres, Omar; Ahn, Changwoo

    2016-05-01

    Aerosol-cloud interaction continues to be one of the leading uncertain components of climate models, primarily due to the lack of an adequate knowledge of the complex microphysical and radiative processes associated with the aerosolcloud system. The situations when aerosols and clouds are found in the same atmospheric column, for instance, when light-absorbing aerosols such as biomass burning generated carbonaceous particles or wind-blown dust overlay low-level cloud decks, are commonly found over several regional of the world. Contrary to the cloud-free scenario over dark surface, for which aerosols are known to produce a net cooling effect (negative radiative forcing) on climate, the overlapping situation of absorbing aerosols over cloud can potentially exert a significant level of atmospheric absorption and produces a positive radiative forcing at top-of-atmosphere. The magnitude of direct radiative effects of aerosols above cloud depends directly on the aerosol loading, microphysical-optical properties of the aerosol layer and the underlying cloud deck, and geometric cloud fraction. We help in addressing this problem by introducing a novel product of optical depth of absorbing aerosols above clouds retrieved from near-UV observations made by the Ozone Monitoring Instrument (OMI) on board NASA's Aura platform. The presence of absorbing aerosols above cloud reduces the upwelling radiation reflected by cloud and produces a strong `color ratio' effect in the near-UV region, which can be unambiguously detected in the OMI measurements. Physically based on this effect, the OMACA algorithm retrieves the optical depths of aerosols and clouds simultaneously under a prescribed state of atmosphere. The algorithm architecture and results from a ten-year global record including global climatology of frequency of occurrence and above-cloud aerosol optical depth, and a discussion on related future field campaigns are presented.

  6. The influence of an external cavity on the emission spectrum of a mercury germicidal lamp

    Science.gov (United States)

    Solomonov, V. I.; Surkov, Yu. S.; Gorbunkov, V. I.

    2016-09-01

    The spectrum of emission from the cylindrical duralumin cavity of a TUV 8wG8 T5 UV industrial germicidal mercury lamp is studied. It is shown that, due to reflection from the inner surface of the cavity and reabsorption in the gas discharge, the resonance line of a mercury atom is significantly weakened. The dependence of the resonance line intensity on the discharge current has a maximum, and the discharge current corresponding to the intensity maximum depends on the reflection coefficient of the inner surface of the cavity.

  7. Constraining the neutrino emission of gravitationally lensed Flat-Spectrum Radio Quasars with ANTARES data

    CERN Document Server

    Adrián-Martínez, S; André, M; Anton, G; Ardid, M; Aubert, J -J; Baret, B; Barrios-Martì, J; Basa, S; Bertin, V; Biagi, S; Bogazzi, C; Bormuth, R; Bou-Cabo, M; Bouwhuis, M C; Bruijn, R; Brunner, J; Busto, J; Capone, A; Caramete, L; Carr, J; Chiarusi, T; Circella, M; Coniglione, R; Core, L; Costantini, H; Coyle, P; Creusot, A; De Rosa, G; Dekeyser, I; Deschamps, A; DeBonis, G; Distefano, C; Donzaud, C; Dornic, D; Dorosti, Q; Drouhin, D; Dumas, A; Eberl, T; Elsässer, D; Enzenhöfer, A; Escoffier, S; Fehn, K; Felis, I; Fermani, P; Folger, F; Fusco, L A; Galatà, S; Gay, P; Geißelsöder, S; Geyer, K; Giordano, V; Gleixner, A; Gómez-González, J P; Graf, K; Guillard, G; van Haren, H; Heijboer, A J; Hello, Y; Hernández-Rey, J J; Herold, B; Herrero, A; Hößl, J; Hofestädt, J; Hugon, C; James, C W; de Jong, M; Kadler, M; Kalekin, O; Kappes, A; Katz, U; Kießling, D; Kooijman, P; Kouchner, A; Kreykenbohm, I; Kulikovskiy, V; Lahmann, R; Lambard, E; Lambard, G; Lefèvre, D; Leonora, E; Loehner, H; Loucatos, S; Mangano, S; Marcelin, M; Margiotta, A; Martínez-Mora, J A; Martini, S; Mathieu, A; Michael, T; Migliozzi, P; Müller, C; Neff, M; Nezri, E; Palioselitis, D; Păvălaş, G E; Perrina, C; Popa, V; Pradier, T; Racca, C; Riccobene, G; Richter, R; Roensch, K; Rostovtsev, A; Saldaña, M; Samtleben, D F E; Sánchez-Losa, A; Sanguineti, M; Schmid, J; Schnabel, J; Schulte, S; Schüssler, F; Seitz, T; Sieger, C; Spies, A; Spurio, M; Steijger, J J M; Stolarczyk, Th; Taiuti, M; Tamburini, C; Tayalati, Y; Trovato, A; Tselengidou, M; Tönnis, C; Vallage, B; Vallée, C; Van Elewyck, V; Visser, E; Vivolo, D; Wagner, S; Wilms, J; de Wolf, E; Yatkin, K; Yepes, H; Zornoza, J D; Zúñiga, J; Falco, E E

    2014-01-01

    Context. The jets of radio-loud Active Galactic Nuclei are among the most powerful particle accelerators in the Universe, and a plausible production site for high-energy cosmic rays. The detection of high-energy neutrinos from these sources would provide unambiguous evidence of a hadronic component in such jets. High-luminosity blazars, such as the flat-spectrum radio quasars (FSRQs), are promising candidates to search for such emission. Because of the low fluxes due to large redshift, these sources are however challenging for the current generation of neutrino telescopes such as ANTARES and IceCube. Aims. This paper proposes to exploit gravitational lensing effects to improve the sensitivity of neutrino telescopes to the intrinsic neutrino emission of distant blazars. Methods. This strategy is illustrated with a search for cosmic neutrinos in the direction of four distant and gravitationally lensed blazars, using data collected from 2007 to 2012 by ANTARES. The magnification factor is estimated for each syst...

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

    Science.gov (United States)

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

    1982-01-01

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

  9. Power spectrum analysis of polarized emission from the Canadian galactic plane survey

    Energy Technology Data Exchange (ETDEWEB)

    Stutz, R. A.; Rosolowsky, E. W. [University of British Columbia Okanagan, 3333 University Way, Kelowna BC, V1V 1V7 (Canada); Kothes, R.; Landecker, T. L. [National Research Council Canada, Dominion Radio Astrophysical Observatory, Box 248, Penticton, BC, V2A 6J9 (Canada)

    2014-05-20

    Angular power spectra are calculated and presented for the entirety of the Canadian Galactic Plane Survey polarization data set at 1.4 GHz covering an area of 1060 deg{sup 2}. The data analyzed are a combination of data from the 100 m Effelsberg Telescope, the 26 m Telescope at the Dominion Radio Astrophysical Observatory, and the Synthesis Telescope at the Dominion Radio Astrophysical Observatory, allowing all scales to be sampled down to arcminute resolution. The resulting power spectra cover multipoles from ℓ ≈ 60 to ℓ ≈ 10{sup 4} and display both a power-law component at low multipoles and a flattening at high multipoles from point sources. We fit the power spectrum with a model that accounts for these components and instrumental effects. The resulting power-law indices are found to have a mode of 2.3, similar to previous results. However, there are significant regional variations in the index, defying attempts to characterize the emission with a single value. The power-law index is found to increase away from the Galactic plane. A transition from small-scale to large-scale structure is evident at b = 9°, associated with the disk-halo transition in a 15° region around l = 108°. Localized variations in the index are found toward H II regions and supernova remnants, but the interpretation of these variations is inconclusive. The power in the polarized emission is anticorrelated with bright thermal emission (traced by Hα emission) indicating that the thermal emission depolarizes background synchrotron emission.

  10. Green's functions technique for calculating the emission spectrum in a quantum dot-cavity system

    Directory of Open Access Journals (Sweden)

    Edgar Arturo Gómez

    2016-12-01

    Full Text Available We introduce the Green's functions technique as an alternative theory to the quantum regression theorem formalism for calculating the two-time correlation functions in open quantum systems at the steady state. In order to investigate the potential of this theoretical approach, we consider a dissipative system composed of a single quantum dot inside a semiconductor cavity and the emission spectrum is computed due to the quantum dot as well as the cavity. We propose an algorithm based on the Green's functions technique for computing the emission spectrum that can easily be adapted to more complex open quantum systems. We found that the numerical results based on the Green's functions technique are in perfect agreement with the quantum regression theorem formalism. Moreover, it allows overcoming the inherent theoretical difficulties associated with the direct application of the quantum regression theorem in open quantum systems. Received: 6 September 2016, Accepted: 5 November 2016; Edited by: J. P. Paz; DOI: http://dx.doi.org/10.4279/PIP.080008 Cite as: E A Gómez, J D Hernández-Rivero, H Vinck-Posada, Papers in Physics 8, 080008 (2016

  11. High-accuracy measurement of the emission spectrum of liquid xenon in the vacuum ultraviolet region

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Keiko, E-mail: fujii-keiko-nv@ynu.jp [Faculty of Engineering, Yokohama National University, Yokohama, Kanagawa 240-8501 (Japan); Endo, Yuya; Torigoe, Yui; Nakamura, Shogo [Faculty of Engineering, Yokohama National University, Yokohama, Kanagawa 240-8501 (Japan); Haruyama, Tomiyoshi; Kasami, Katsuyu [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan); Mihara, Satoshi; Saito, Kiwamu; Sasaki, Shinichi [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan); The Graduate School of Advanced Studies, Hayama, Kanagawa 240-0193 (Japan); Tawara, Hiroko [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan)

    2015-09-21

    The emission spectrum of cryogenic liquid xenon in the vacuum ultraviolet region was measured by irradiating liquid xenon with gamma-rays from a radioactive source. To achieve a high signal-to-noise ratio, we employed coincident photon counting. Additionally, the charge of the photo-sensor signals was measured to estimate the number of detected photons accurately. In addition, proper corrections were incorporated for the wavelength; response functions of the apparatus obtained using a low-pressure mercury lamp, and photon detection efficiencies of the optical system were considered. The obtained emission spectrum is found to be in the shape of a Gaussian function, with the center at 57,199±34 (stat.)±33 (syst.) cm{sup −1} (174.8±0.1 (stat.)±0.1 (syst.) nm) and the full width at half maximum of 3328±72 (stat.)±65 (syst.) cm{sup −1} (10.2±0.2 (stat.)±0.2 (sys.) nm). These results are the most accurate values obtained in terms of the data acquisition method and the calibration for the experimental system and provide valuable information regarding the high-precision instruments that employ a liquid-xenon scintillator.

  12. Ambient temperature dependence on emission spectrum of InAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Ngo, C.Y.; Yoon, S.F. [School of Electrical and Electronic Engineering, Nanyang Technological University (Singapore); Chua, S.J. [Institute of Materials Research and Engineering, Faculty of Engineering (Singapore)

    2009-04-15

    Semiconductor superluminescent diodes (SLDs) are important broadband light source for fiber optic gyroscope and biomedical imaging. Quantum dots (QDs) have been proposed to be the best candidate for broadband light sources due to the inhomogeneous broadening of the gain spectrum as a result of the inherited size inhomogeneity of the self-assembled QD growth. In this work, the effect of ambient temperature (25-100 C) on the emission spectrum of InAs QDs with wideband emission was investigated. It was found that the full-width at half-maximum (FWHM) of the photoluminescence (PL) spectra remains more than 125 nm throughout the temperature range, and the redshift as function of temperature is approximately 0.27 meV/K. Activation energy of 270 meV is extracted from the Arrhenius plot and the PL quenching at high temperature is attributed to thermally induced carriers escaping out of the In{sub 0.15}Ga{sub 0.85}As strain-reducing layer. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Injected spectrum for TeV-γ-ray emission from the galactic center

    Institute of Scientific and Technical Information of China (English)

    Yan-Ping Wang; Ye Lu; Li Chen

    2009-01-01

    The detection of very high energy γ-ray emission from the Galactic center has been reported by four independent groups. One of these γ-ray sources, the 10TeV γ-ray radiation reported by HESS, has been suggested as having a hadronic origin when relativistic protons are injected into and interact with the dense ambient gas. Assuming that such relativistic protons required by the hadronic model come from the tidal disruption of a star by the massive black hole of Sgr A*, we explore the spectrum of the relativistic protons. In the calculations, we investigate cases where different types of stars are tidally disrupted by the black hole of Sgr A*, and we consider that different diffusion mechanisms are used for the propagation of protons. The initial energy distribution of the injected spectrum of protons is assumed to follow a power-law with an exponential cut-off, and we derive the different indices of the injected spectra for the tidal disruption of different types of stars. For the best fit to the spectrum of photons detected by HESS, the spectral index of the injected relativistic protons is about 2.05 when a red giant is tidally disrupted by the black hole of Sgr A* and the diffusion mechanism is the Effective Confinement of Protons.

  14. Steep-spectrum sources and the duty cycle of the radio emission

    CERN Document Server

    Orienti, M

    2010-01-01

    It is currently accepted that intrinsically compact and bright radio sources characterized by a convex spectrum peaking at frequencies ranging from 100 MHz to a few GHz are young objects. Following the evolutionary models, these objects would evolve into the population of classical radio galaxies. However, the fraction of young radio sources in flux density-limited samples is much larger than what expected from the number counts of large radio sources. This may suggest that for some reason a significant fraction of young objects would never become large radio galaxies with sizes up to a few Mpc. The discovery of the young radio source PKS 1518+047 characterized by an uncommonly steep spectrum confirms that the radio emission may switch off shortly after its onset. Then the source spectrum steepens and evolves due to energy losses. If the interruption is not temporary, the fate of the fading sources is to disappear at frequencies lower than those explored by current radio telescopes. Fossils of past activities...

  15. The Spectrum of Isotropic Diffuse Gamma-Ray Emission Between 100 Mev and 820 Gev

    Science.gov (United States)

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Brandt, T. J.; Hays, E.; Perkins, J. S.

    2014-01-01

    The gamma-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse gamma-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission, and a longer data accumulation of 50 months, allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature, and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 plus or minus 0.02 and a break energy of (279 plus or minus 52) GeV using our baseline diffuse Galactic emission model. The total intensity attributed to the IGRB is (7.2 plus or minus 0.6) x 10(exp -6) cm(exp -2) s(exp -1) sr(exp -1) above 100 MeV, with an additional +15%/-30% systematic uncertainty due to the Galactic diffuse foregrounds.

  16. The Mid-Infrared Spectrum of Star-Forming Galaxies: Global Properties of PAH Emission

    CERN Document Server

    Smith, J D T; Dale, D A; Moustakas, J; Kennicutt, R C; Helou, G; Armus, L; Roussel, H; Sheth, K; Bendo, G J; Buckalew, B A; Engelbracht, C W; Gordon, K D; Hollenbach, D J; Li, A; Malhotra, S; Murphy, E J; Walter, F

    2006-01-01

    We present a sample of low-resolution 5-38um Spitzer IRS spectra of the inner few square kiloparsecs of 59 nearby galaxies spanning a large range of star formation properties. A robust method for decomposing mid-infrared galaxy spectra is described, and used to explore the behavior of PAH emission and the prevalence of silicate dust extinction. Evidence for silicate extinction is found in ~1/8 of the sample, at strengths which indicate most normal galaxies undergo A_V < ~3 magnitudes averaged over their centers. The contribution of PAH emission to the total infrared power is found to peak near 10% and extend up to ~20%, and is suppressed at metallicities Z < ~Z_sun/4, as well as in low-luminosity AGN environments. Strong inter-band PAH feature strength variations (2-5x) are observed, with the presence of a weak AGN and, to a lesser degree, increasing metallicity shifting power to the longer wavelength bands. A peculiar PAH emission spectrum with markedly diminished 5-8um features arises among the sample...

  17. A ground-based near-infrared emission spectrum of the exoplanet HD 189733b.

    Science.gov (United States)

    Swain, Mark R; Deroo, Pieter; Griffith, Caitlin A; Tinetti, Giovanna; Thatte, Azam; Vasisht, Gautam; Chen, Pin; Bouwman, Jeroen; Crossfield, Ian J; Angerhausen, Daniel; Afonso, Cristina; Henning, Thomas

    2010-02-01

    Detection of molecules using infrared spectroscopy probes the conditions and compositions of exoplanet atmospheres. Water (H(2)O), methane (CH(4)), carbon dioxide (CO(2)), and carbon monoxide (CO) have been detected in two hot Jupiters. These previous results relied on space-based telescopes that do not provide spectroscopic capability in the 2.4-5.2 microm spectral region. Here we report ground-based observations of the dayside emission spectrum for HD 189733b between 2.0-2.4 microm and 3.1-4.1 microm, where we find a bright emission feature. Where overlap with space-based instruments exists, our results are in excellent agreement with previous measurements. A feature at approximately 3.25 microm is unexpected and difficult to explain with models that assume local thermodynamic equilibrium (LTE) conditions at the 1 bar to 1 x 10(-6) bar pressures typically sampled by infrared measurements. The most likely explanation for this feature is that it arises from non-LTE emission from CH(4), similar to what is seen in the atmospheres of planets in our own Solar System. These results suggest that non-LTE effects may need to be considered when interpreting measurements of strongly irradiated exoplanets.

  18. Strong-field effects in the photo-emission spectrum of the C$_{60}$ fullerene

    CERN Document Server

    Gao, Cong-Zhang; Kluepfel, Peter; Meier, Chris; Reinhard, Paul-Gerhard; Suraud, Eric

    2016-01-01

    Considering C$_{60}$ as a model system for describing field emission from the extremity of a carbon nanotip, we explore electron emission from this fullerene excited by an intense, near-infrared, few-cycle laser pulse ($10^{13}$-$10^{14}~{\\rm W/cm}^2$, 912 nm, 8-cycle). To this end, we use time-dependent density functional theory augmented by a self-interaction correction. The ionic background of C$_{60}$ is described by a soft jellium model. Particular attention is paid to the high energy electrons. Comparing the spectra at different emission angles, we find that, as a major result of this study, the photoelectrons are strongly peaked along the laser polarization axis forming a highly collimated electron beam in the forward direction, especially for the high energy electrons. Moreover, the high-energy plateau cut-off found in the simulations agrees well with estimates from the classical three-step model. We also investigate the build-up of the high-energy part of a photoelectron spectrum by a time-resolved a...

  19. Mechanism of generation of the emission bands in the dynamic spectrum of the Crab pulsar

    CERN Document Server

    Ardavan, H; Singleton, J; Pérez, M

    2008-01-01

    We show that the proportionately spaced emission bands in the dynamic spectrum of the Crab pulsar (Hankins T. H. & Eilek J. A., 2007, ApJ, 670, 693) fit the oscillations of the square of a Bessel function whose argument exceeds its order. This function has already been encountered in the analysis of the emission from a polarization current with a superluminal distribution pattern: a current whose distribution pattern rotates (with an angular frequency $\\omega$) and oscillates (with a frequency $\\Omega>\\omega$ differing from an integral multiple of $\\omega$) at the same time (Ardavan H., Ardavan A. & Singleton J., 2003, J Opt Soc Am A, 20, 2137). Using the results of our earlier analysis, we find that the dependence on frequency of the spacing and width of the observed emission bands can be quantitatively accounted for by an appropriate choice of the value of the single free parameter $\\Omega/\\omega$. In addition, the value of this parameter, thus implied by Hankins & Eilek's data, places the last ...

  20. A ground-based near-infrared emission spectrum of the exoplanet HD 189733b

    CERN Document Server

    Swain, Mark R; Griffith, Caitlin A; Tinetti, Giovanna; Thatte, Azam; Vasisht, Gautam; Chen, Pin; Bouwman, Jeroen; Crossfield, Ian J; Angerhausen, Daniel; Afonso, Cristina; Henning, Thomas

    2010-01-01

    Detection of molecules using infrared spectroscopy probes the conditions and compositions of exoplanet atmospheres. Water (H2O), methane (CH4), carbon dioxide (CO2), and carbon monoxide (CO) have been detected in two hot Jupiters. These previous results relied on space-based telescopes that do not provide spectroscopic capability in the 2.4 - 5.2 micron spectral region. Here we report ground-based observations of the dayside emission spectrum for HD 189733b between 2.0-2.4 micron and 3.1-4.1 micron, where we find a bright emission feature. Where overlap with space-based instruments exists, our results are in excellent agreement with previous measurements. A feature at ~3.25 micron is unexpected and difficult to explain with models that assume local thermodynamic equilibrium (LTE) conditions at the 1 bar to 1 x 10-6 bar pressures typically sampled by infrared measurements. The most likely explanation for this feature is that it arises from non-LTE emission from CH4, similar to what is seen in the atmospheres o...

  1. On the Evolution of and High-Energy Emission from GHz-Peaked-Spectrum Sources

    Energy Technology Data Exchange (ETDEWEB)

    Stawarz, L.; Ostorero, L.; Begelman, M.C.; Moderski, R.; Kataoka, J.; Wagner, S.

    2007-12-18

    Here we discuss evolution and broad-band emission of compact (< kpc) lobes in young radio sources. We propose a simple dynamical description for these objects, consisting of a relativistic jet propagating into a uniform gaseous medium in the central parts of an elliptical host. In the framework of the proposed model, we follow the evolution of ultrarelativistic electrons injected from a terminal hotspot of a jet to expanding lobes, taking into account their adiabatic energy losses as well as radiative cooling. This allows us to discuss the broad-band lobe emission of young radio sources. In particular, we argue that the observed spectral turnover in the radio synchrotron spectra of these objects cannot originate from the synchrotron self-absorption process but is most likely due to free-free absorption effects connected with neutral clouds of interstellar medium engulfed by the expanding lobes and photoionized by active centers. We also find a relatively strong and complex high-energy emission component produced by inverse-Compton up-scattering of various surrounding photon fields by the lobes electrons. We argue that such high energy radiation is strong enough to account for several observed properties of GHz-peaked-spectrum (GPS) radio galaxies at UV and X-ray frequencies. In addition, this emission is expected to extend up to GeV (or possibly even TeV) photon energies and can thus be probed by several modern {gamma}-ray instruments. In particular, we suggest that GPS radio galaxies should constitute a relatively numerous class of extragalactic sources detected by GLAST.

  2. Locally Optimally Emitting Clouds and the Variable Broad Emission Line Spectrum of NGC 5548

    Science.gov (United States)

    Korista, Kirk T.; Goad, Michael R.

    2000-06-01

    In recent work Baldwin et al. proposed that in the geometrically extended broad-line regions (BLRs) of quasars and active galactic nuclei, a range in line-emitting gas properties (e.g., density, column density) might exist at each radius and showed that under these conditions the broad emission line spectra of these objects may be dominated by selection effects introduced by the atomic physics and general radiative transfer within the large pool of line-emitting entities. In this picture, the light we see originates in a vast amalgam of emitters but is dominated by those emitters best able to reprocess the incident continuum into a particular emission line. We test this ``locally optimally emitting clouds'' (LOC) model against the extensive spectroscopic database of the Seyfert 1 galaxy NGC 5548. The time-averaged, integrated-light UV broad emission line spectrum from the 1993 Hubble Space Telescope (HST) monitoring campaign is reproduced via the optimization of three global geometric parameters: the outer radius, the index controlling the radial cloud covering fraction of the continuum source, and the integrated cloud covering fraction. We make an ad hoc selection from the range of successful models, and for a simple spherical BLR geometry we simulate the emission-line light curves for the 1989 IUE and 1993 HST campaigns, using the respective observed UV continuum light curves as drivers. We find good agreement between the predicted and observed light curves and lags-a demonstration of the LOC picture's viability as a means to understanding the BLR environment. Finally, we discuss the next step in developing the LOC picture, which involves the marriage of echo-mapping techniques with spectral simulation grids such as those presented here, using the constraints provided by a high-quality, temporally well-sampled spectroscopic data set.

  3. Hybrid white light sources based on layer-by-layer assembly of nanocrystals on near-UV emitting diodes

    Science.gov (United States)

    Nizamoglu, Sedat; Demir, Hilmi Volkan

    2007-10-01

    We present the design, growth, fabrication, integration and characterization of alternative hybrid white light sources based on the controlled layer-by-layer assembly of nanocrystals on UV-emitting nitride diodes for adjustable white light parameters. We hybridize CdSe/ZnS core-shell nanocrystals of different sizes (1.9-3.2-5.2 nm) on InGaN/GaN LEDs as a near-UV excitation source at 383 nm for efficient pumping. The first device includes layer-by-layer assembly of dichromatic cyan- and red-emitting nanocrystals (λPL = 504-615 nm) leading to the tristimulus coordinates (x = 0.37,y = 0.46); the second device uses the trichromatic combination of layer-by-layer hybridized cyan-, yellow- and red-emitting nanocrystals (λPL = 504-580-615 nm), yielding (x = 0.38,y = 0.48). Such layer-by-layer hybridization offers the advantages of precisely controlling individual nanocrystal film thicknesses and order in addition to concentrations. By utilizing such multiple combinations of nanocrystals in the assembly, the light parameters are well controlled and adjusted. Leveraging rapidly advancing UV technology into efficient lighting with nanocrystal based color conversion, it is critical to develop and demonstrate hybrid light sources on UV pumping platforms.

  4. Synthesis, characteristics and luminescent properties of a new Tb(III) ternary complex applied in near UV-based LED

    Science.gov (United States)

    Sun, Naiqun; Li, Liping; Yang, Yamin; Zhang, Aiqin; Jia, Husheng; Liu, Xuguang; Xu, Bingshe

    2015-11-01

    A novel Tb(III) ternary complex, Tb(p-BBA)3UA, was synthesized with 4-benzoylbenzoic acid (p-BBA) as primary ligand and undecylenic acid (UA) as reactive ligand. Tb(III) complex exhibits high thermal stability and wide and strong excitation bands from 310 nm to 400 nm when monitored at 543 nm, which matches well with the 365 nm UV chip. The complex displays Tb(III) characteristic peaks at 488, 543, 584 and 619 nm under the excitation of 365 nm UV-light. The intramolecular energy transfer process was also discussed. Meanwhile, the complex has longer fluorescence lifetime (1.317 ms) and higher quantum yield (44.8%). When used in LED with 365 nm UV chip (power efficiency is 17.3 lm/W), the complex still maintained its qualified luminescent performance. All the results indicate that Tb(p-BBA)3UA can be applied as a green component for fabrication of near UV-based white LED.

  5. Ground-based near-UV observations of 15 transiting exoplanets: Constraints on their atmospheres and no evidence for asymmetrical transits

    CERN Document Server

    Turner, Jake D; Biddle, Lauren I; Smart, Brianna M; Zellem, Robert T; Teske, Johanna K; Hardegree-Ullman, Kevin K; Griffith, Caitlin C; Leiter, Robin M; Cates, Ian T; Nieberding, Megan N; Smith, Carter-Thaxton W; Thompson, Robert M; Hofmann, Ryan; Berube, Michael P; Nguyen, Chi H; Small, Lindsay C; Guvenen, Blythe C; Richardson, Logan; McGraw, Allison; Raphael, Brandon; Crawford, Benjamin E; Robertson, Amy N; Tombleson, Ryan; Carleton, Timothy M; Towner, Allison P M; Walker-LaFollette, Amanda M; Hume, Jeffrey R; Watson, Zachary T; Jones, Christen K; Lichtenberger, Matthew J; Hoglund, Shelby R; Cook, Kendall L; Crossen, Cory A; Jorgensen, Curtis R; Thompson, James M Romine Alejandro R; Villegas, Christian F; Wilson, Ashley A; Sanford, Brent; Taylor, Joanna M

    2016-01-01

    Transits of exoplanets observed in the near-UV have been used to study the scattering properties of their atmospheres and possible star-planet interactions. We observed the primary transits of 15 exoplanets (CoRoT-1b, GJ436b, HAT-P-1b, HAT-P-13b, HAT-P-16b, HAT-P-22b, TrES-2b, TrES-4b, WASP-1b, WASP-12b, WASP-33b, WASP-36b, WASP-44b, WASP-48b, and WASP-77Ab) in the near-UV and several optical photometric bands to update their planetary parameters, ephemerides, search for a wavelength dependence in their transit depths to constrain their atmospheres, and determine if asymmetries are visible in their light curves. Here we present the first ground-based near-UV light curves for 12 of the targets (CoRoT-1b, GJ436b, HAT-P-1b, HAT-P-13b, HAT-P-22b, TrES-2b, TrES-4b, WASP-1b, WASP-33b, WASP-36b, WASP-48b, and WASP-77Ab). We find that none of the near-UV transits exhibit any non-spherical asymmetries, this result is consistent with recent theoretical predictions by Ben-Jaffel et al. and Turner et al. The multi-wavele...

  6. Fluorescence Efficiency and Visible Re-emission Spectrum of Tetraphenyl Butadiene Films at Extreme Ultraviolet Wavelengths

    CERN Document Server

    Gehman, V M; Rielage, K; Hime, A; Sun, Y; Mei, D -M; Maassen, J; Moore, D

    2011-01-01

    A large number of current and future experiments in neutrino and dark matter detection use the scintillation light from noble elements as a mechanism for measuring energy deposition. The scintillation light from these elements is produced in the extreme ultraviolet (EUV) range, from 60 - 200 nm. Currently, the most practical technique for observing light at these wavelengths is to surround the scintillation volume with a thin film of Tetraphenyl Butadiene (TPB) to act as a fluor. The TPB film absorbs EUV photons and reemits visible photons, detectable with a variety of commercial photosensors. Here we present a measurement of the re-emission spectrum of TPB films when illuminated with 128, 160, 175, and 250 nm light. We also measure the fluorescence efficiency as a function of incident wavelength from 120 to 250 nm.

  7. Detection of an unidentified emission line in the stacked X-ray spectrum of galaxy clusters

    Energy Technology Data Exchange (ETDEWEB)

    Bulbul, Esra; Foster, Adam; Smith, Randall K.; Randall, Scott W. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Markevitch, Maxim [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Loewenstein, Michael, E-mail: ebulbul@cfa.harvard.edu [CRESST and X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-07-01

    We detect a weak unidentified emission line at E = (3.55-3.57) ± 0.03 keV in a stacked XMM-Newton spectrum of 73 galaxy clusters spanning a redshift range 0.01-0.35. When the full sample is divided into three subsamples (Perseus, Centaurus+Ophiuchus+Coma, and all others), the line is seen at >3σ statistical significance in all three independent MOS spectra and the PN 'all others' spectrum. It is also detected in the Chandra spectra of the Perseus Cluster. However, it is very weak and located within 50-110 eV of several known lines. The detection is at the limit of the current instrument capabilities. We argue that there should be no atomic transitions in thermal plasma at this energy. An intriguing possibility is the decay of sterile neutrino, a long-sought dark matter particle candidate. Assuming that all dark matter is in sterile neutrinos with m{sub s} = 2E = 7.1 keV, our detection corresponds to a neutrino decay rate consistent with previous upper limits. However, based on the cluster masses and distances, the line in Perseus is much brighter than expected in this model, significantly deviating from other subsamples. This appears to be because of an anomalously bright line at E = 3.62 keV in Perseus, which could be an Ar XVII dielectronic recombination line, although its emissivity would have to be 30 times the expected value and physically difficult to understand. Another alternative is the above anomaly in the Ar line combined with the nearby 3.51 keV K line also exceeding expectation by a factor of 10-20. Confirmation with Astro-H will be critical to determine the nature of this new line.

  8. Amplified spontaneous emission spectrum at the output of a diode amplifier saturated by an input monochromatic wave

    Science.gov (United States)

    Bogatov, A. P.; Drakin, A. E.; D'yachkov, N. V.; Gushchik, T. I.

    2016-08-01

    Expressions for the amplitudes of amplified spontaneous emission waves in a diode amplifier near the frequency ω0 of a 'strong' input monochromatic wave have been derived in terms of a random function of a stationary Gaussian process. We have found expressions for the spectral density of the amplitudes and shown that, on the red side of the spectrum with respect to frequency ω0, spontaneous emission waves obtain additional nonlinear gain, induced by the strong wave, whereas on the blue side of the spectrum an additional loss is induced. Such behaviour of the amplitudes of amplified waves agrees with previous results.

  9. Back reaction, the Hawking emission spectrum from the charged black hole

    Energy Technology Data Exchange (ETDEWEB)

    Xu Pingchuan; Wang Zhihong [Institute of Theoretical Physics, China West Normal University, Nanchong, Sichuan 637002 (China); Han Yan, E-mail: pcxu@163.com [College of Mathematic and Information, China West Normal University, Nanchong, Sichuan 637002 (China)

    2011-06-21

    The Hawking emission spectrum of the Schwarzschild-like black hole has been successfully described in the tunneling picture. In this paper, we develop the idea for the case of the charged black hole with back reaction. First, the most general, static spherically symmetric charged black hole, in the presence of back reaction, has been provided by solving the Einstein equations with a non-zero vacuum expectation value of the energy-momentum tensor (T{sub {mu}{nu}}({phi}, g{sub {mu}{nu}})). At the one-loop corrections, we also produce the modified expressions for the Hawking temperature and Bekenstein-Hawking entropy. It is found that the leading correction to the semiclassical entropy is logarithmic and next to the leading order is inverse of the horizon area, just as the expected well-known results. In particular, as our main focus in this paper, we show that the modified black hole still radiates with a perfect blackbody spectrum, only the temperature undergoing quantum corrections. Also, the Hawking fluxes of the electric current and energy-momentum tensor to include the effect of back reaction are obtained. The results are interestingly found sharing the same form as that from the point of anomaly.

  10. The Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived From First-Year Fermi Large Area Telescope Data

    Energy Technology Data Exchange (ETDEWEB)

    Abdo, A. A.

    2011-08-19

    We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called 'extra-galactic' diffuse {gamma}-ray emission (EGB). This component of the diffuse {gamma}-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modelling of the bright foreground diffuse Galactic {gamma}-ray emission (DGE), the detected LAT sources and the solar {gamma}-ray emission. We find the spectrum of the EGB is consistent with a power law with differential spectral index {gamma} = 2.41 {+-} 0.05 and intensity, I(> 100 MeV) = (1.03 {+-} 0.17) x 10{sup -5} cm{sup -2} s{sup -1} sr{sup -1}, where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.

  11. Spontaneous emission spectrum of a three-level atom embedded in photonic crystal

    Institute of Scientific and Technical Information of China (English)

    刘国强; 王健; 张汉壮

    2005-01-01

    The two models of three-level (one upper level and two lower levels, or two upper levels and one lower level) atom embedded in a double-band photonic crystal are adopted. The atomic transitions from the upper levels to the lower levels are assumed to be coupled by the same reservoir which are respectively the isotropic photonic band gap (PBG)modes, the anisotropic PBG modes and the free vacuum modes. The effects of the fine structure of the atomic ground state levels in the model with one upper level and two lower levels, and the quantum interferences in the model with two upper levels and one lower level on the spontaneous emission spectrum of an atom are investigated in detail. Most interestingly, it is shown that new spontaneous emission lines are produced from the fine splitting of atomic ground state levels in the isotropic PBG case. The quantum interferences induce additional narrow spontaneous lines near the transition from the empty upper level to the lower level.

  12. Locally Optimally-Emitting Clouds and the Variable Broad Emission Line Spectrum of NGC 5548

    CERN Document Server

    Korista, K T; Korista, Kirk T.; Goad, Michael R.

    2000-01-01

    [abridged] We test the ``locally optimally-emitting clouds'' (LOC) model against the extensive spectroscopic data base of the Seyfert~1, NGC 5548. The time-averaged, integrated-light UV broad emission line spectrum from the 1993 global geometric parameters: the outer radius, the index controlling the radial cloud covering fraction of the continuum source, and the integrated cloud covering fraction. We make an {\\em ad~hoc} selection from the range of successful models, and for a simple spherical BLR geometry we simulate the emission line light curves for the 1989 {\\em IUE} and 1993 {\\em HST} campaigns, using the respective observed UV continuum light curves as drivers. We find good agreement between the predicted and observed light curves and lags --- a demonstration of the LOC picture's viability as a means to understanding the BLR environment. Finally, we discuss the next step in developing the LOC picture which involves the marriage of echo-mapping techniques with spectral simulation grids such as those pre...

  13. LOFAR insights into the epoch of reionization from the cross-power spectrum of 21 cm emission and galaxies

    NARCIS (Netherlands)

    Wiersma, R. P. C.; Ciardi, B.; Thomas, R. M.; Harker, G. J. A.; Zaroubi, S.; Bernardi, G.; Brentjens, M.; de Bruyn, A. G.; Daiboo, S.; Jelic, V.; Kazemi, S.; Koopmans, L. V. E.; Labropoulos, P.; Martinez, O.; Offringa, A.; Pandey, V. N.; Schaye, J.; Veligatla, V.; Vedantham, H.; Yatawatta, S.; Mellema, G.

    2013-01-01

    Using a combination of N-body simulations, semi-analytic models and radiative transfer calculations, we have estimated the theoretical cross-power spectrum between galaxies and the 21 cm emission from neutral hydrogen during the epoch of reionization. In accordance with previous studies, we find tha

  14. Understanding different efficiency droop behaviors in InGaN-based near-UV, blue and green light-emitting diodes through differential carrier lifetime measurements

    CERN Document Server

    Wang, Lai; Wang, Jiaxing; Hao, Zhibiao; Luo, Yi; Sun, Changzheng; Han, Yanjun; Xiong, Bing; Wang, Jian; Li, Hongtao

    2016-01-01

    Efficiency droop effect under high injection in GaN-based light emitting diodes (LEDs) strongly depends on wavelength, which is still not well understood. In this paper, through differential carrier lifetime measurements on commercialized near-UV, blue, and green LEDs, their different efficiency droop behaviors are attributed to different carrier lifetimes, which are prolonged as wavelength increases. This relationship between carrier lifetime and indium composition of InGaN quantum well is believed owing to the polarization-induced quantum confinement Stark effect. Long carrier lifetime not only increases the probability of carrier leakage, but also results in high carrier concentration in quantum well. In other words, under the same current density, the carrier concentration in active region in near-UV LED is the lowest while that in green one is the highest. If considering the efficiency droop depending on carrier concentration, the behaviors of LEDs with different wavelengths do not show any abnormality. ...

  15. Ground-based near-UV observations of 15 transiting exoplanets: Constraints on their atmospheres and no evidence for asymmetrical transits

    OpenAIRE

    Turner, Jake D.; Pearson, Kyle A.; Biddle, Lauren I.; Smart, Brianna M.; Zellem, Robert T.; Teske, Johanna K.; Hardegree-Ullman, Kevin K.; Griffith, Caitlin C.; Leiter, Robin M.; Cates, Ian T.; Nieberding, Megan N.; Smith, Carter-Thaxton W.; Thompson, Robert M.; Hofmann, Ryan; Berube, Michael P.

    2016-01-01

    Transits of exoplanets observed in the near-UV have been used to study the scattering properties of their atmospheres and possible star-planet interactions. We observed the primary transits of 15 exoplanets (CoRoT-1b, GJ436b, HAT-P-1b, HAT-P-13b, HAT-P-16b, HAT-P-22b, TrES-2b, TrES-4b, WASP-1b, WASP-12b, WASP-33b, WASP-36b, WASP-44b, WASP-48b, and WASP-77Ab) in the near-UV and several optical photometric bands to update their planetary parameters, ephemerides, search for a wavelength dependen...

  16. Ortho-vanadates K{sub 3}RE(VO{sub 4}){sub 2} (RE = La, Pr, Eu, Gd, Dy, Y) for near UV-converted phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Lin [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Wei, Dong-Lei [Department of Physics and Center for Marine-Integrated Biomedical Technology, Pukyong National University, Busan 608-737 (Korea, Republic of); Huang, Yanlin [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Qin, Chuanxiang, E-mail: qinchuanxiang@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Cai, Peiqing; Kim, Sun-Il [Department of Physics and Center for Marine-Integrated Biomedical Technology, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo-Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Center for Marine-Integrated Biomedical Technology, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2014-10-15

    The orthovanadate poly-crystals K{sub 3}RE(VO{sub 4}){sub 2} (RE = La, Pr, Eu, Gd, Dy, Y) were synthesized via the solid-state reaction route. The crystal phase formation was verified through X-ray diffraction (XRD) studies and was performed by structural refinements. The optical properties were also investigated in detail. K{sub 3}RE(VO{sub 4}){sub 2} (RE = Eu, Dy, Gd, Pr, La, Y) phosphors present different luminescence behaviors: the profiles of excitation and emission spectra, the spectra shift, the luminescence decay lifetimes, the absolute quantum efficiency (QE), and the CIE color coordinates are very different. The luminescence of K{sub 3}RE(VO{sub 4}){sub 2} (RE = La, Gd, Y, Pr) presents yellow or yellowish green color, while, K{sub 3}Dy(VO{sub 4}){sub 2} and K{sub 3}Eu(VO{sub 4}){sub 2} show white and red luminescence, respectively. This was discussed on the base of the different micro-structure, activator centers, and the charge transfer transitions from [VO{sub 4}]{sup 3−} groups in the lattices. K{sub 3}Y(VO{sub 4}){sub 2} and K{sub 3}Eu(VO{sub 4}){sub 2} show higher QE values of 47.0% and 45.0% at room temperature, respectively. All the phosphors have efficient absorption in the region of near-UV wavelengths or blue wavelength region. This can well match with the light from UV-LED (360–400 nm) or blue LED chips (450–480 nm) based on GaN semiconductor. K{sub 3}RE(VO{sub 4}){sub 2} could be suggested to be a potential candidate to give further investigations for the application on near-UV excited white LEDs. - Graphical abstract: A series of orthovanadates K{sub 3}RE(VO{sub 4}){sub 2} (RE = Eu, Dy, Gd, Pr, La, Y) have been developed to be new phosphors with rich luminescence colors; there are efficiency excitation in the near UV wavelength region. Compared with the reported vanadate phosphors K{sub 3}R(VO{sub 4}){sub 2} has rich luminescence color, rich color, no concentration quenching, and comparable luminescence QE. - Highlights: • A

  17. Evolution of the complex refractive index in the near UV spectral region in ageing secondary organic aerosol

    Directory of Open Access Journals (Sweden)

    J. M. Flores

    2014-02-01

    Full Text Available The chemical and physical properties of secondary organic aerosol (SOA formed by the photochemical degradation of biogenic and anthropogenic volatile organic compounds (VOC are yet poorly constrained. The evolution of the complex refractive index (RI of SOA, formed from purely biogenic VOC and mixtures of biogenic and anthropogenic VOC was studied over a diurnal cycle in the SAPHIR photochemical outdoor chamber in Jülich, Germany. The correlation of RI with SOA chemical and physical properties such as oxidation level and volatility was examined. The RI was retrieved by a newly developed broadband cavity enhanced spectrometer for aerosol optical extinction measurements in the near UV spectral region (360 to 420 nm. Chemical composition and volatility of the particles were monitored by a high resolution time of flight aerosol mass spectrometer, and a volatility tandem differential mobility analyzer. SOA was formed by ozonolysis of either (i a mixture of biogenic VOC (α-pinene and limonene, (ii biogenic VOC mixture with subsequent addition of an anthropogenic VOC (p-xylene-d10, or (iii a mixture of biogenic and anthropogenic VOC. The SOA aged by ozone / OH reactions up to 29.5 h was found to be non-absorbing in all cases. The SOA with p-xylene-d10 showed an increase of the scattering component of the RI correlated with an increase of the O / C ratio and with an increase in the SOA density. There was a greater increase in the scattering component of the RI when the SOA was produced from the mixture of biogenic VOCs and anthropogenic VOC than from the sequential addition of the VOCs after the approximate same ageing time. The increase of the scattering component was inversely correlated with the SOA volatility. Two RI retrievals determined for the pure biogenic SOA showed a constant RI for up to 5 h of ageing. Mass spectral characterization shows the three types of the SOA formed in this study have significant amount of semivolatile components. The

  18. Evolution of the complex refractive index in the near UV spectral region in ageing secondary organic aerosol

    Science.gov (United States)

    Flores, J. M.; Zhao, D. F.; Segev, L.; Schlag, P.; Kiendler-Scharr, A.; Fuchs, H.; Watne, Å. K.; Bluvshtein, N.; Mentel, Th. F.; Hallquist, M.; Rudich, Y.

    2014-02-01

    The chemical and physical properties of secondary organic aerosol (SOA) formed by the photochemical degradation of biogenic and anthropogenic volatile organic compounds (VOC) are yet poorly constrained. The evolution of the complex refractive index (RI) of SOA, formed from purely biogenic VOC and mixtures of biogenic and anthropogenic VOC was studied over a diurnal cycle in the SAPHIR photochemical outdoor chamber in Jülich, Germany. The correlation of RI with SOA chemical and physical properties such as oxidation level and volatility was examined. The RI was retrieved by a newly developed broadband cavity enhanced spectrometer for aerosol optical extinction measurements in the near UV spectral region (360 to 420 nm). Chemical composition and volatility of the particles were monitored by a high resolution time of flight aerosol mass spectrometer, and a volatility tandem differential mobility analyzer. SOA was formed by ozonolysis of either (i) a mixture of biogenic VOC (α-pinene and limonene), (ii) biogenic VOC mixture with subsequent addition of an anthropogenic VOC (p-xylene-d10), or (iii) a mixture of biogenic and anthropogenic VOC. The SOA aged by ozone / OH reactions up to 29.5 h was found to be non-absorbing in all cases. The SOA with p-xylene-d10 showed an increase of the scattering component of the RI correlated with an increase of the O / C ratio and with an increase in the SOA density. There was a greater increase in the scattering component of the RI when the SOA was produced from the mixture of biogenic VOCs and anthropogenic VOC than from the sequential addition of the VOCs after the approximate same ageing time. The increase of the scattering component was inversely correlated with the SOA volatility. Two RI retrievals determined for the pure biogenic SOA showed a constant RI for up to 5 h of ageing. Mass spectral characterization shows the three types of the SOA formed in this study have significant amount of semivolatile components. The influence

  19. Study of Temporal Evolution of Emission Spectrum in a Steeply Rising Submillimeter Burst

    CERN Document Server

    Li, J P; Wang, X D

    2015-01-01

    In the paper the spectral temporal evolution of a steeply rising submillimeter (THz) burst occurred on 2003 November 2 was investigated in detail for the first time. Observations show that the flux density of the THz spectrum increased steeply with frequency above 200 GHz. Their average rising rates reached a value of 235 sfu/GHz (corresponding spectral index $\\alpha$ of 4.8) during the burst. The flux densities reached about 4,000 and 70,000 sfu at 212 and 405 GHz at maximum phase, respectively. The emissions at 405 GHz maintained continuous high level that they exceed largely the peak values of the microwave (MW) spectra during the main phase. Our studies suggest that only energetic electrons with a low-energy cutoff of $\\sim$1 MeV and number density of $\\sim$$10^{6}$--$10^{8}$ cm$^{-3}$ can produce such strong and steeply rising THz component via gyrosynchrotron (GS) radiation based on numerical simulations of burst spectra in the nonuniform magnetic field case. The electron number density $N$, derived fro...

  20. Imprint of DESI fiber assignment on the anisotropic power spectrum of emission line galaxies

    CERN Document Server

    Pinol, Lucas; Hand, Nick; Seljak, Uros; White, Martin

    2016-01-01

    The Dark Energy Spectroscopic Instrument (DESI), a multiplexed fiber-fed spectrograph, is a Stage-IV ground-based dark energy experiment aiming to measure redshifts for 29 million Emission-Line Galaxies (ELG), 4 million Luminous Red Galaxies (LRG), and 2 million Quasi-Stellar Objects (QSO). The survey design includes a pattern of tiling on the sky and the locations of the fiber positioners in the focal plane of the telescope, with the observation strategy determined by a fiber assignment algorithm that optimizes the allocation of fibers to targets. This strategy allows a given region to be covered on average five times for a five-year survey, but with coverage varying between zero and twelve, which imprints a spatially-dependent pattern on the galaxy clustering. We investigate the systematic effects of the fiber assignment coverage on the anisotropic galaxy clustering of ELGs and show that, in the absence of any corrections, it leads to discrepancies of order ten percent on large scales for the power spectrum...

  1. Power Spectrum Analysis of Polarized Emission from the Canadian Galactic Plane Survey

    CERN Document Server

    Stutz, R A; Kothes, R; Landecker, T

    2014-01-01

    Angular power spectra are calculated and presented for the entirety of the Canadian Galactic Plane Survey polarization dataset at 1.4 GHz covering an area of 1060 deg$^2$. The data analyzed are a combination of data from the 100-m Effelsberg Telescope, the 26-m Telescope at the Dominion Radio Astrophysical Observatory, and the Synthesis Telescope at the Dominion Radio Astrophysical Observatory, allowing all scales to be sampled down to arcminute resolution. The resulting power spectra cover multipoles from $\\ell \\approx 60$ to $\\ell \\approx 10^4$ and display both a power-law component at low multipoles and a flattening at high multipoles from point sources. We fit the power spectrum with a model that accounts for these components and instrumental effects. The resulting power-law indices are found to have a mode of 2.3, similar to previous results. However, there are significant regional variations in the index, defying attempts to characterize the emission with a single value. The power-law index is found to ...

  2. Semiconductor diode laser material and devices with emission in visible region of the spectrum

    Science.gov (United States)

    Ladany, I.; Kressel, H.

    1975-01-01

    Two alloy systems, (AlGa)As and (InGa)P, were studied for their properties relevant to obtaining laser diode operation in the visible region of the spectrum. (AlGa)As was prepared by liquid-phase epitaxy (LPE) and (InGa)P was prepared both by vapor-phase epitaxy and by liquid-phase epitaxy. Various schemes for LPE growth were applied to (InGa)P, one of which was found to be capable of producing device material. All the InGaP device work was done using vapor-phase epitaxy. The most successful devices were fabricated in (AlGa)As using heterojunction structures. At room temperature, the large optical cavity design yielded devices lasing in the red (7000 A). Because of the relatively high threshold due to the basic band structure limitation in this alloy, practical laser diode operation is presently limited to about 7300 A. At liquid-nitrogen temperature, practical continuous-wave operation was obtained at a wavelength of 6500 to 6600 A, with power emission in excess of 50 mW. The lowest pulsed lasing wavelength is 6280 A. At 223 K, lasing was obtained at 6770 A, but with high threshold currents. The work dealing with CW operation at room temperature was successful with practical operation having been achieved to about 7800 A.

  3. Genomic Survey and Biochemical Analysis of Recombinant Candidate Cyanobacteriochromes Reveals Enrichment for Near UV/Violet Sensors in the Halotolerant and Alkaliphilic Cyanobacterium Microcoleus IPPAS B353.

    Science.gov (United States)

    Cho, Sung Mi; Jeoung, Sae Chae; Song, Ji-Young; Kupriyanova, Elena V; Pronina, Natalia A; Lee, Bong-Woo; Jo, Seong-Whan; Park, Beom-Seok; Choi, Sang-Bong; Song, Ji-Joon; Park, Youn-Il

    2015-11-20

    Cyanobacteriochromes (CBCRs), which are exclusive to and widespread among cyanobacteria, are photoproteins that sense the entire range of near-UV and visible light. CBCRs are related to the red/far-red phytochromes that utilize linear tetrapyrrole (bilin) chromophores. Best characterized from the unicellular cyanobacterium Synechocystis sp. PCC 6803 and the multicellular heterocyst forming filamentous cyanobacteria Nostoc punctiforme ATCC 29133 and Anabaena sp. PCC 7120, CBCRs have been poorly investigated in mat-forming, nonheterocystous cyanobacteria. In this study, we sequenced the genome of one of such species, Microcoleus IPPAS B353 (Microcoleus B353), and identified two phytochromes and seven CBCRs with one or more bilin-binding cGMP-specific phosphodiesterase, adenylyl cyclase and FhlA (GAF) domains. Biochemical and spectroscopic measurements of 23 purified GAF proteins from phycocyanobilin (PCB) producing recombinant Escherichia coli indicated that 13 of these proteins formed near-UV and visible light-absorbing covalent adducts: 10 GAFs contained PCB chromophores, whereas three contained the PCB isomer, phycoviolobilin (PVB). Furthermore, the complement of Microcoleus B353 CBCRs is enriched in near-UV and violet sensors, but lacks red/green and green/red CBCRs that are widely distributed in other cyanobacteria. We hypothesize that enrichment in short wavelength-absorbing CBCRs is critical for acclimation to high-light environments where this organism is found.

  4. Conditions for Statistical Determination of the Neutrino Mass Spectrum in Radiative Emission of Neutrino Pairs in Atoms

    CERN Document Server

    Song, Ningqiang; Gomez-Cadenas, J J; Gonzalez-Garcia, M C; Conde, A Peralta; Taron, Josep

    2015-01-01

    The photon spectrum in macrocoherent atomic de-excitation via radiative emission of neutrino pairs (RENP) has been proposed as a sensitive probe of the neutrino mass spectrum, capable of competing with conventional neutrino experiments. In this paper we revisit this intriguing technique in order to quantify the requirements for statistical determination of some of the properties of the neutrino spectrum, in particular the neutrino mass scale and the mass ordering. Our results are sobering. We find that, even under ideal conditions, the determination of neutrino parameters needs experimental live times of the order of days to years for several laser frequencies, assuming a target of volume of order 100 cm3 containing about 10^21 atoms per cubic centimeter in a totally coherent state with maximum value of the electric field in the target. Such conditions seem to be, as of today, way beyond the reach of our current technology.

  5. Near-IR Emission Spectrum of WASP-103b using Hubble Space Telescope/Wide Field Camera 3

    CERN Document Server

    Cartier, Kimberly M S; Zhao, Ming; Line, Michael; Ngo, Henry; Mawet, Dimitri; Stassun, Keivan G; Wright, Jason T; Kreidberg, Laura; Fortney, Jonathan; Knutson, Heather

    2016-01-01

    We present here our observations and analysis of the dayside emission spectrum of the hot Jupiter WASP-103b. We observed WASP-103b during secondary eclipse using two visits of the Hubble Space Telescope with the G141 grism on Wide Field Camera 3 in spatial scan mode. We generated secondary eclipse light curves of the planet in both blended white-light and spectrally binned wavechannels from 1.1-1.7 micron and corrected the light curves for flux contamination from a nearby companion star. We modeled the detector systematics and secondary eclipse spectrum using Gaussian process regression and found that the near-IR emission spectrum of WASP-103b is featureless across the observed near-IR region to down to a sensitivity of 175 ppm, and shows a shallow slope towards the red. The atmosphere has a single brightness temperature of T_B = 2890 K across this wavelength range. This region of the spectrum is indistinguishable from isothermal, but may not manifest from a physically isothermal system, i.e. pseudo-isotherma...

  6. Multi-spectrum retrieval of Venus IR surface emissivity maps from VIRTIS/VEX nightside measurements at Themis Regio

    Science.gov (United States)

    Kappel, David; Arnold, Gabriele; Haus, Rainer

    2016-02-01

    Surface emissivity maps in the infrared can contribute to explore Venus' geology. Nightside radiance spectra at Themis Regio acquired by the IR mapping channel of the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS-M-IR) aboard Venus EXpress (VEX) are used to derive emissivity data from the three accessible spectral surface windows at 1.02, 1.10, and 1.18 μm. The measured spectra are simulated by applying a full radiative transfer model. Neglecting geologic activity, a multi-spectrum retrieval algorithm is utilized to determine the emissivity maps of the surface target as parameter vectors that are common to many spectrally resolved images that cover this target. Absolute emissivity values are difficult to obtain due to strong interferences from other parameters. The true emissivity mean of the target cannot be retrieved, nor can the emissivity mean of a retrieved map be strictly preset. The retrieved map can exhibit trends with latitude and topography that are probably artificial. Once the trends have been removed in a post-processing step, it can be observed that the magnitude of the resulting spatial emissivity fluctuations around their mean value increases with increasing mean value. A linear transformation is applied that converts the de-trended map to exhibit a defined emissivity mean value called reference emissivity, here 0.5, yielding the 'renormalized emissivity map' with accordingly transformed fluctuations. It is verified that renormalized emissivity maps are largely independent of the emissivity mean before renormalization, of modifications to interfering atmospheric, surface, and instrumental parameters, and of selected details of the retrieval pipeline and data calibration and preprocessing. Extremely large emissivity retrieval errors due to imperfect or unconsidered forward model parameters are effectively avoided. If the absolute emissivity at a given bin of the target were known, the absolute emissivity map of the entire target could be

  7. Effects of Hydrogen-bonding Interaction and Polarity on Emission Spectrum of Naphthalene-Triethylamine in Mixed Solvent

    Institute of Scientific and Technical Information of China (English)

    XIE Guo-bin; Yoshimi Sueishi; Shunzo Yamamoto

    2004-01-01

    The effects of the protic and aprotic polar solvents on the emission spectrum of the naphthalene-triethylamine system in THF were studied under conditions of steady-state illumination. The fluorescence spectrum of the naphthalene-triethylamine system consists of two emission bands, the fluorescence band of naphthalene (band A, 329 nm) and the emission band of the exciplex(band B, 468 nm). The intensities of both the emission bands decrease with increasing the solvent polarity. The intensity of band B also decreases due to the hydrogen-bonding interaction between triethylamine and protic solvent, while that of band A increases. It is thus suggested that the quenching of naphthalene fluorescence by triethylamine in THF occurs through the charge transfer and electron transfer reactions. The spectral changes upon the increase of solvent polarity can be explained by the dependences of the equilibrium constant between exciplex and ion-pair and the rate constant for the electron transfer reaction from triethylamine to the excited naphthalene on the relative permittivity of solvent. It is shown that the formation of intermolecular hydrogen-bonding between triethylamine and protic solvent suppresses the quenching reaction by the decrease in free amine. Acetonitrile has only a polar effect and trichloroacetic acid only a hydrogen-bonding(or protonation) effect, while alcohols have both the effects. The effects of alcohols could be separated into the effects of solvent polarity and intermolecular hydrogen-bonding interaction quantitatively.

  8. Local electron spectrum above 100 MeV derived from gamma-ray emissivity spectra

    Science.gov (United States)

    Strong, A. W.

    1985-01-01

    Two new determinations of the local gamma-ray emmissivity spectrum are in good accord and were used to derive constraints on the local electron spectrum. The requirement for an electron intensity above 1 GeV larger than previously believed is confirmed and no low energy upturn is then needed.

  9. Near-infrared Emission Spectrum of WASP-103b Using Hubble Space Telescope/Wide Field Camera 3

    Science.gov (United States)

    Cartier, Kimberly M. S.; Beatty, Thomas G.; Zhao, Ming; Line, Michael; Ngo, Henry; Mawet, Dimitri; Stassun, Keivan G.; Wright, Jason T.; Kreidberg, Laura; Fortney, Jonathan; Knutson, Heather

    2017-01-01

    We present here our observations and analysis of the dayside emission spectrum of the hot Jupiter WASP-103b. We observed WASP-103b during secondary eclipse using two visits of the Hubble Space Telescope with the G141 grism on Wide Field Camera 3 in spatial scan mode. We generated secondary eclipse light curves of the planet in both blended white-light and spectrally binned wavechannels from 1.1 {to} 1.7 μ {{m}} and corrected the light curves for flux contamination from a nearby companion star. We modeled the detector systematics and secondary eclipse spectrum using Gaussian process regression and found that the near-IR emission spectrum of WASP-103b is featureless across the observed near-IR region to down to a sensitivity of 175 ppm, and shows a shallow slope toward the red. The atmosphere has a single brightness temperature of {T}{{B}}=2890 K across this wavelength range. This region of the spectrum is indistinguishable from isothermal, but may not manifest from a physically isothermal system, i.e., pseudo-isothermal. A solar-metallicity profile with a thermal inversion layer at 10‑2 bar fits the spectrum of WASP-103b with high confidence, as do an isothermal profile with solar metallicity and a monotonically decreasing atmosphere with C/O > 1. The data rule out a monotonically decreasing atmospheric profile with solar composition, and we rule out a low-metallicity decreasing profile as unphysical for this system. The pseudo-isothermal profile could be explained by a thermal inversion layer just above the layer probed by our observations, or by clouds or haze in the upper atmosphere. Transmission spectra at optical wavelengths would allow us to better distinguish between potential atmospheric models. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  10. 应变补偿InGaN/AlGaN超晶格改善近紫外LED性能%Near-UV LED photoelectric properties of strain-compensated InGaN/AlGaN superlattice layers

    Institute of Scientific and Technical Information of China (English)

    尹以安; 章勇; 范广涵; 李述体

    2015-01-01

    通过应变平衡理论设计出应变补偿的In0.1Ga0.9N/Al0.2Ga0.8N超晶格结构。为了验证该结构具有低的应变,实验生长了相应的样品,并通过双晶衍射(XRD)和拉曼(Raman)光谱实验证实其具有低应力。最后把该结构用于近紫外LED的两处构建,一是替代量子阱中的GaN垒层,二是作p型层的接触层。实验发现,该结构的应用不但可以减弱量子阱的Stark效应和抑制电子泄露,而且降低p型接触层的欧姆接触电阻。且发现不用电子阻挡层情况下,其输出功率、PL光谱和I-V特性等都得到极大改善。%The strain-compensated In0.1Ga0.9N/Al0.2Ga0.8N superlattice structure was designed by strain equilibrium theory. To verify the structure with low stress, p-InGaN/p-AlGaN superlattice lattice layers (SLs) with a strain-compensated structure was fabricated by epitaxial growth technology, and low stress in the structure was verified by double-crystal x-ray diffraction (XRD) and Raman spectroscopy (Raman). The experimental results show that the near-UV LEDs with strain-compensated In0.1Ga0.9N/Al0.2Ga0.8N SLs have higher emission power over their conventional counterparts with GaN barriers due to the mitigation of the quantum-confined Stark effect and the suppression of electron leakage. Furthermore, the performances of the near-UV LEDs with proposed InGaN/AlGaN barriers can be further improved without electron blocking layers.

  11. Emission spectrum from an Al/Mg tracer in the blow-off region of a radiativelv ablated cansule

    Institute of Scientific and Technical Information of China (English)

    Pu Yu-Dong; Chen Bo-Lun; Zhang Lu; Yang Jia-Min; Huang Tian-Xuan; Ding Yong-Kun

    2011-01-01

    A study of X-ray emissions from Al/Mg tracers buried at two different depths in a plastic shell is presented. The X-rays originating from the K-shell transitions of the Al/Mg ions begin to irradiate after the ablative heating wave has passed through the trace layer and are recorded with a streaked crystal spectrometer. Only emissions from the capsule with the trace layer buried at a smaller depth are observed. Hydrodynamic simulations and a collisional-radiative model including detailed atomic physics are used to investigate the measured spectrum. It is found that the effects of the radiative heating play important roles in the formation of the K-shell emission. The time correlation between the simulations and the measurements is obtained by comparing the measured time profile of the He a emission with the calculated one. The line ratio of Ly a to He a is also calculated and is found to be in fairly good agreement with the experimental data. Finally,the relation between the time profile of the He a emission and the ablation velocity is also discussed.

  12. Formation Mechanism and Emission Spectrum of AlO Radicals in Reaction of Laser-ablated Al Atom and Oxygen

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu-dong; LI Hai-Yang

    2003-01-01

    The emission spectrum of AlO radicals was analyzed in 440-540 nm in the reaction of laser ablated Al beam and O2. The carrier of spectrum was assigned to Δν=0, ±1, ±2 vibrational sequences of B2Σ+-X2Σ+ transition of AlO radicals, the observed maximum vibrational quantum number was ν′=6. The rotational and vibrational temperatures of B state were estimated at 3000 and 7500 K by spectrally simulating the rovibronic population distribution. There is a strong evidence that the production of excited Al(2S) atoms is essential to the formation of excited AlO radicals.

  13. Possibility of precise measurement of the cosmological power spectrum with a dedicated survey of 21 cm emission after reionization.

    Science.gov (United States)

    Loeb, Abraham; Wyithe, J Stuart B

    2008-04-25

    Measurements of the 21 cm line emission by residual cosmic hydrogen after reionization can be used to trace the power spectrum of density perturbations through a significant fraction of the observable volume of the Universe. We show that a dedicated 21 cm observatory could probe a number of independent modes that is 2 orders of magnitude larger than currently available, and enable a cosmic-variance limited detection of the signature of a neutrino mass approximately 0.05 eV. The evolution of the linear growth factor with redshift could also constrain exotic theories of gravity or dark energy to an unprecedented precision.

  14. The angular power spectrum measurement of the Galactic synchrotron emission in two fields of the TGSS survey

    Science.gov (United States)

    Choudhuri, Samir; Bharadwaj, Somnath; Ali, Sk. Saiyad; Roy, Nirupam; Intema, Huib. T.; Ghosh, Abhik

    2017-09-01

    Characterizing the diffuse Galactic synchrotron emission at arcminute angular scales is needed to reliably remove foregrounds in cosmological 21-cm measurements. The study of this emission is also interesting in its own right. Here, we quantify the fluctuations of the diffuse Galactic synchrotron emission using visibility data for two of the fields observed by the TIFR GMRT Sky Survey. We have used the 2D Tapered Gridded Estimator to estimate the angular power spectrum (Cℓ) from the visibilities. We find that the sky signal, after subtracting the point sources, is likely dominated by the diffuse Galactic synchrotron radiation across the angular multipole range 240 ≤ ℓ ≲ 500. We present a power-law fit, C_{ℓ}=A× \\big (1000/l\\big )^{β }, to the measured Cℓ over this ℓ range. We find that (A, β) have values (356 ± 109 mK2, 2.8 ± 0.3) and (54 ± 26 mK2, 2.2 ± 0.4) in the two fields. For the second field, however, there is indication of a significant residual point source contribution and for this field we interpret the measured Cℓ as an upper limit for the diffuse Galactic synchrotron emission. While in both fields the slopes are consistent with earlier measurements, the second field appears to have an amplitude that is considerably smaller compared to similar measurements in other parts of the sky.

  15. The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV

    CERN Document Server

    Ackermann, M; Albert, A; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Bissaldi, E; Blandford, R D; Bloom, E D; Bottacini, E; Brandt, T J; Bregeon, J; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Caragiulo, M; Caraveo, P A; Cavazzuti, E; Cecchi, C; Charles, E; Chekhtman, A; Chiang, J; Chiaro, G; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Cuoco, A; Cutini, S; D'Ammando, F; de Angelis, A; de Palma, F; Dermer, C D; Digel, S W; Silva, E do Couto e; Drell, P S; Favuzzi, C; Ferrara, E C; Focke, W B; Franckowiak, A; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Germani, S; Giglietto, N; Giommi, P; Giordano, F; Giroletti, M; Godfrey, G; Gomez-Vargas, G A; Grenier, I A; Guiriec, S; Gustafsson, M; Hadasch, D; Hayashi, K; Hays, E; Hewitt, J W; Ippoliti, P; Jogler, T; Jóhannesson, G; Johnson, A S; Johnson, W N; Kamae, T; Kataoka, J; Knödlseder, J; Kuss, M; Larsson, S; Latronico, L; Li, J; Li, L; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Manfreda, A; Massaro, F; Mayer, M; Mazziotta, M N; McEnery, J E; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nemmen, R; Nuss, E; Ohsugi, T; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Panetta, J H; Perkins, J S; Pesce-Rollins, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Romani, R W; Sánchez-Conde, M; Schaal, M; Schulz, A; Sgrò, C; Siskind, E J; Spandre, G; Spinelli, P; Strong, A W; Suson, D J; Takahashi, H; Thayer, J G; Thayer, J B; Tibaldo, L; Tinivella, M; Torres, D F; Tosti, G; Troja, E; Uchiyama, Y; Vianello, G; Werner, M; Winer, B L; Wood, K S; Wood, M; Zaharijas, G; Zimmer, S

    2014-01-01

    The {\\gamma}-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse {\\gamma}-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission, and a longer data accumulation of 50 months, allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a sig...

  16. X-ray emission from open star clusters with Spectrum-Rontgen-Gamma

    DEFF Research Database (Denmark)

    Singh, K.P.; Ojha, D.K.; Schnopper, H.W.;

    1998-01-01

    throughput of SPECTRUM-Rontgen-Gamma will help detect main sequence stars like Sun in middle-aged and old clusters. We will study the relationships between various parameters - age, rotation, abundance, UBV colors, X-ray luminosity, coronal temperature etc. X-ray spectra of younger and brighter populations...

  17. A qubit strongly coupled to a resonant cavity: asymmetry of the spontaneous emission spectrum beyond the rotating wave approximation

    Energy Technology Data Exchange (ETDEWEB)

    Cao, X [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, 361005 (China); You, J Q; Nori, F [Advanced Science Institute, RIKEN, Wako-shi 351-0198 (Japan); Zheng, H, E-mail: xfcao@xmu.edu.cn [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2011-07-15

    We investigate the spontaneous emission (SE) spectrum of a qubit in a lossy resonant cavity. We use neither the rotating-wave approximation nor the Markov approximation. For the weak-coupling case, the SE spectrum of the qubit is a single peak, with its location depending on the spectral density of the qubit environment. Then, the asymmetry (of the location and heights of the two peaks) of the two SE peaks (which are related to the vacuum Rabi splitting) changes as the qubit-cavity coupling increases. Explicitly, for a qubit in a low-frequency intrinsic bath, the height asymmetry of the splitting peaks is enhanced as the qubit-cavity coupling strength increases. However, for a qubit in an Ohmic bath, the height asymmetry of the spectral peaks is inverted compared to the low-frequency bath case. With further increasing the qubit-cavity coupling to the ultra-strong regime, the height asymmetry of the left and right peaks is slightly inverted, which is consistent with the corresponding case of a low-frequency bath. This inversion of the asymmetry arises from the competition between the Ohmic bath and the cavity bath. Therefore, after considering the anti-rotating terms, our results explicitly show how the height asymmetry in the SE spectrum peaks depends on the qubit-cavity coupling and the type of intrinsic noise experienced by the qubit.

  18. High energy emission from flat-spectrum radio sources with ˜ kpc-scale structure

    Science.gov (United States)

    Augusto, Pedro

    Active Galactic Nuclei emit a substantial portion of their bolometric luminosities in X-rays. For example, the knots in radio jets are prominent sources of synchrotron X-rays while the hotspots of the brightest FRIIs emit self-synchrotron or Inverse Compton radiation. Most high-energy studies on flat-spectrum radio sources have been conducted for blazars which are dominant at γ-rays.Augusto et al. (1998) have built a sample of 55 flat-spectrum radio sources dominated by structures (knots, hotspots, etc.) ˜0.1-2 kpc away from the nucleus. Seventeen (31%) of these are detected in X-rays (they tend to be the radio strongest) evenly splitting, morphologically, both at optical (radio) bands: nine QSO/BLLac (core-jets) on one-side; eight Galaxy/Sy2 (CSO/MSO/FRII) on the other. We have identified five confirmed compact/medium symmetric objects (CSO/MSOs) as X-ray emitters. A comparable type of source to CSO/MSOs is the physically similar (1-15 kpc) compact steep spectrum source (CSS), 28/129 (22%) of which are detected in X-rays, from a literature-selected sample (the percentage is smaller than for the 55-source sample due to a lower ). A 95% conf. level relation is found for CSSs: S_X ∝ (S4.85)0.6 and we found undistinguishable radio/X-ray properties for both the 55-source and CSS samples: clearly, their similar morphologies (e.g. knots in jets) stand up stronger than their radical radio spectrum differences.Only two sources among the 55 (4%) have γ-ray detections and they seem quite abnormal (in αxγ values, at least)-one of them is in a Sy2, not in a blazar.

  19. Non-equilibrium electron features in X-ray emission spectrum from inertial confinement fusion implosions

    Science.gov (United States)

    Kagan, Grigory; Landen, O. L.; Svyatsky, D.; Thorn, D.; Schneider, M. B.; Bradley, D.; Kilkenny, J. D.

    2016-10-01

    An X-ray spectrometer proposed for the National Ignition Facility will infer the imploded core electron temperature from the free-free continuum spectra of the emitted photons with energies of 15 to 30 keV. In this range reabsorption rates are low so one might expect a rather unambiguous temperature measurement from the spectrum slope at the higher energy cut-off. It can be noticed, however, that the harder X-ray radiation is emitted by the tail of the electron distribution. The mean- free-path for the suprathermal electrons is much larger than for their thermal counterparts, making this tail to deviate from Maxwellian and obscuring interpretation of the data. We utilize solutions for the reduced kinetic equation to investigate modification to the X-ray spectra due to suprathermal electrons' deviation from equilibrium. The logarithmic slope of the spectrum from the depleted electron distribution is found to increasingly drop at higher photon energies compared to the case of perfectly Maxwellian electrons. Interpreting the spectrum from a depleted distribution with assumption of Maxwellian electrons enforced gives the electron temperature lower than the actual one. The newly predicted effects are further enhanced in the presence of hydrodynamic mix. This work is performed under the auspices of the U.S. Department of Energy by the Los Alamos National Security, LLC, Los Alamos National Laboratory under Contract No. DE-AC52-06NA25396.

  20. Sub-photospheric, radiation mediated shocks in GRBs: Multiple shock emission and the Band spectrum

    CERN Document Server

    Keren, Shai

    2014-01-01

    We compute the time integrated, thermal emission produced by a series of radiation mediated shocks that emerge from the photosphere of a GRB outflow. We show that for a sufficiently broad distribution of shock strengths, the overall shape of the time integrated spectral energy distribution below the peak is a power law, $\

  1. Constraining the neutrino emission of gravitationally lensed Flat-Spectrum Radio Quasars with ANTARES data

    NARCIS (Netherlands)

    Adrián-Martínez, S.; Albert, A.; André, M.; Anton, G.; Ardid, M.; Aubert, J. J.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bogazzi, C.; Bormuth, R.; Bou-Cabo, M.; Bouwhuis, M. C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Chiarusi, T.; Circella, M.; Coniglione, R.; Core, L.; Costantini, H.; Coyle, P.; Creusot, A.; De Rosa, G.; Dekeyser, I.; Deschamps, A.; De Bonis, G.; Distefano, C.; Donzaud, C.; Dornic, D.; Dorosti, Q.; Drouhin, D.; Dumas, A.; Eberl, T.; Elsässer, D.; Enzenhöfer, A.; Escoffier, S.; Fehn, K.; Felis, I.; Fermani, P.; Folger, F.; Fusco, L. A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Gómez-González, J. P.; Graf, K.; Guillard, G.; Haren, H. Van; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Herold, B.; Herrero, A.; Hößl, J.; Hofestädt, J.; Hugon, C.; James, C. W.; De Jong, M.; Kadler, M.; Kalekin, O.; Kappes, A.; Katz, U.; Kießling, D.; Kooijman, P.; Kouchner, A.; Kreykenbohm, I.; Kulikovskiy, V.; Lahmann, R.; Lambard, E.; Lambard, G.; Lefèvre, D.; Leonora, E.; Loehner, H.; Loucatos, S.; Mangano, S.; Marcelin, M.; Margiotta, A.; Martínez-Mora, J. A.; Martini, S.; Mathieu, A.; Michael, T.; Migliozzi, P.; Müller, C.; Neff, M.; Nezri, E.; Palioselitis, D.; Pəvəlaš, G. E.; Perrina, C.; Popa, V.; Pradier, T.; Racca, C.; Riccobene, G.; Richter, R.; Roensch, K.; Rostovtsev, A.; Saldaña, M.; Samtleben, D. F E; Sánchez-Losa, A.; Sanguineti, M.; Schmid, J.; Schnabel, J.; Schulte, S.; Schüssler, F.; Seitz, T.; Sieger, C.; Spies, A.; Spurio, M.; Steijger, J. J M; Stolarczyk, Th; Taiuti, M.; Tamburini, C.; Tayalati, Y.; Trovato, A.; Tselengidou, M.; Tönnis, C.; Vallage, B.; Vallée, C.; Elewyck, V. Van; Visser, E.; Vivolo, D.; Wagner, S.; Wilms, J.; De Wolf, E.; Yatkin, K.; Yepes, H.; Zornoza, J. D.; Zúñiga, J.; Falco, E. E.

    2014-01-01

    This paper proposes to exploit gravitational lensing effects to improve the sensitivity of neutrino telescopes to the intrinsic neutrino emission of distant blazar populations. This strategy is illustrated with a search for cosmic neutrinos in the direction of four distant and gravitationally lensed

  2. Biased impurity tunneling current emission spectrum in the presence of quasi-particle interaction

    Science.gov (United States)

    Maslova, N. S.; Arseyev, P. I.; Mantsevich, V. N.

    2016-09-01

    We performed theoretical investigations of the tunneling current noise spectra through single-level impurity in the presence of quasi-particle (electron-phonon) interaction by means of the non-equilibrium Green function formalism. We demonstrated a fundamental link between quantum noise in tunneling contact and light emission processes. We calculated tunneling current noise spectra through a single level impurity atom both in the presence and in the absence of quasi-particle interaction for a finite bias voltage and identified it as a source of experimentally observed light emission from bias STM contacts. The results turn out to be sensitive to the tunneling contact parameters. Our findings provide important insight into the nature of non-equilibrium electronic transport in tunneling junctions with quasi-particle interaction.

  3. [Quantitative inversion of rock SiO2 content based on thermal infrared emissivity spectrum].

    Science.gov (United States)

    Yang, Hang; Zhang, Li-Fu; Huang, Zhao-Qiang; Zhang, Xue-Wen; Tong, Qing-Xi

    2012-06-01

    The present paper used the emissivity of non-processed rocks measured by M304, a hyperspectral Fourier transform infrared (FTIR) spectroradiometer, and SiO2 content by the X-ray fluorescence spectrometry. After continuum removal and normalization, stepwise regress method was employed to select the feature bands of rocks emissivity. And then quantitative relationship between SiO2 content and continuum removal emissivity of feature bands was analysed. Based on that, by comparing twelve SiO2 indices models, the optimal model for predicting SiO2 content was built. The result showed that the SiO2 indices can predict SiO2 content efficiently, and especially the normalization silicon dioxide index (NSDI) about 11.18 and 12.36 microm is the best; compared with regression models, NSDI is simpler and has higher practicality; the result has an important application value in rock classification and SiO2 content extraction with high precision.

  4. An Impurity Emission Survey in the near UV and Visible Spectral Ranges of Electron Cyclotron Heated (ECH) Plasma in the TJ-II Stellarator

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, K. J.; Zurro, B.; Baciero, A.

    2001-07-01

    We report on a near-ultraviolet and visible spectroscopic survey (220-600 nm) of electron cyclotron resonance (ECR) heated plasmas created in the TJ-II stellarator, with central electron temperatures up to 2 keV and central electron densities up to 1.7 x 10 ''19 m''-3. Approximately 1200 lines from thirteen elements have been identified. The purpose of the work is to identify the principal impurities and spectral lines present in TJ-II plasmas, as well as their possible origin to search for transitions from highly ionised ions. This work will act as a base for identifying suitable transitions for following the evolution of impurities under different operating regimens and multiplet systems for line polarisation studies. It is intended to use the database creates as a spectral line reference for comparing spectra under different operating and plasma heating regimes. (Author)

  5. Population Dynamics and Emission Spectrum of a Cascade Three-Level Jaynes-Cummings Model with Intensity-Dependent Coupling in a Kerr-like Medium

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    By using the method of eigenvectors, the atomic populations and emission spectrum are investigated in a system that consists of a cascade three-level atom resonantly interacting with a single-mode field in a Kerr-like medium.The atom and the field are assumed to be initially in the upper atomic state and the Fock state, respectively. Results for models with intensity-dependent coupling and with intensity-independent coupling are compared. It is found that both population dynamics and emission spectrum show no indications of atom-field decoupling in the strong field limit if the intensity-dependent coupling is taken into account.

  6. The 2.4 micron spectrum of Comet Halley - A search for H2 emission

    Science.gov (United States)

    Smith, W. Hayden; Wolstencroft, Ramon D.; Lutz, Barry L.

    1989-01-01

    A 2.4-micron spectrum of Comet Halley was obtained on April 1, 1986 with the UKIRT scanning Fabry-Perot-CVF equipped with an InSb detector. From the ratio of the measured flux from comet Halley to Zeta Her in the 8.8 x 10 to the -4th micron bandwidth, Comet Halley produced a detected flux of about 1.3 x 10 to the 5th photons/sec with a 1-sigma variance of 385 photons. The flux detected in the same spectral region by Maillard et al. (1986) agrees with the measurements reported here to within a factor of two. The data obtained are examined from the standpoint of the possible mechanisms of H2 production.

  7. CH^+ Spectrum and Diffuse Interstellar Bands Toward Herschel 36 Excited by Dust Emission

    Science.gov (United States)

    Dahlstrom, Julie; Oka, Takeshi; Johnson, Sean; Welty, Daniel E.; Hobbs, Lew M.; York, Donald G.

    2012-06-01

    All electronic CH^+ interstellar absorption lines so far observed had been limited to the R(0) transition starting from the J = 0 ground level; this is because of the very rapid J = 1 → 0 spontaneous emission with the life time of ˜ 140 s. We have observed the R(1) and Q(1) lines of the A^1π ← X^1Σ band from the excited J = 1 level 40.08 K (27.86 cm-1) above the J = 0 level toward Herschel 36 indicating high radiative temperature of T_r = 17.5 K. The high temperature is most likely due to far infrared dust emission from the Her 36 SE. We have also observed the R_1(3/2) line of CH starting from the excited fine structure level J = 3/2 which is 25.76 - 25.57 K above the J = 1/2 level. The effect of high radiative temperature is also noticed as unique lineshapes of diffuse interstellar bands (DIBs) observed toward Her 36. We have examined seven DIBs including λ 5780.5, λ 5797.1, λ 6190.0, and λ 6613.0 that are correlated with each other with correlation coefficients > 0.93. While for ordinary sightlines the lineshapes of these DIBs are more or less symmetric, those toward Her 36 show a long tail toward the red. This is due to far infrared pumping of high J rotational levels of polar carriers of the DIBs by the dust emission. We have developed a model calculation of relaxation taking into account of both radiative and collisional processes. A linear molecule with about 6 carbon atoms can explain some of the DIBs. For the DIBs we have examined, probably the carriers are of this size since we cannot explain the large difference between the DIBs toward ordinary sightlines and toward Her 36 with larger molecules. Goto, M., Stecklum, B., Linz, H., Feldt, M., Henning, Th., Pascucci, I., and Usuda, T. 2006, ApJ, {649} 299.

  8. An Ultraviolet Spectrum of the Tidal Disruption Flare ASASSN-14li

    CERN Document Server

    Cenko, S Bradley; Roth, Nathaniel; Veilleux, Sylvain; Prochaska, J Xavier; Yan, Lin; Guillochon, James; Maksym, W Peter; Arcavi, Iair; Butler, Nathaniel R; Filippenko, Alexei V; Fruchter, Andrew S; Gezari, Suvi; Kasen, Daniel; Levan, Andrew J; Miller, Jon M; Pasham, Dheeraj R; Ramirez-Ruiz, Enrico; Strubbe, Linda E; Tanvir, Nial R; Tombesi, Francesco

    2016-01-01

    We present a Hubble Space Telescope STIS spectrum of ASASSN-14li, the first rest-frame UV spectrum of a tidal disruption flare (TDF). The underlying continuum is well fit by a blackbody with $T_{\\mathrm{UV}} = 3.5 \\times 10^{4}$ K, an order of magnitude smaller than the temperature inferred from X-ray spectra (and significantly more precise than previous efforts based on optical and near-UV photometry). Super-imposed on this blue continuum, we detect three classes of features: narrow absorption from the Milky Way (probably a High-Velocity Cloud), and narrow absorption and broad (FWHM $\\approx 2000$-8000 km s$^{-1}$) emission lines at/near the systemic host velocity. The absorption lines are blueshifted with respect to the emission lines by $\\Delta v = -(250$-400) km s$^{-1}$. Together with the lack of common low-ionization features (Mg II, Fe II), we argue these arise from the same absorbing material responsible for the low-velocity outflow discovered at X-ray wavelengths. The broad nuclear emission lines dis...

  9. The absorption and emission spectrum of radiative cooling galactic fountain gas

    Science.gov (United States)

    Benjamin, Robert A.; Shapiro, Paul R.

    1993-01-01

    We have calculated the time-dependent, nonequilibrium thermal and ionization history of gas cooling radiatively from 10(exp 6) K in a one-dimensional, planar, steady-state flow model of the galactic fountain, including the effects of radiative transfer. Our previous optically thin calculations explored the effects of photoionization on such a flow and demonstrated that self-ionization was sufficient to cause the flow to match the observed galactic halo column densities of C 4, Si 4, and N 5 and UV emission from C 4 and O 3 in the constant density (isochoric) limit, which corresponded to cooling regions homogeneous on scales D less than or approximately equal to 1 kpc. Our new calculations which take full account of radiative transfer confirm the importance of self-ionization in enabling such a flow to match the data but allow a much larger range for cooling region sizes, i.e. D(sub 0) greater than or approximately equal to 15 pc. For an initial flow velocity v(sub 0) approximately equal to 100 km/s, comparable to the sound speed of a 10(exp 6) K gas, the initial density is found to be n(sub h,0) is approximately 2 x 10(exp -2) cm(exp -3), in reasonable agreement with other observation estimates, and D(sub 0) is approximately equal to 40 pc. We also compare predicted H(alpha) fluxes, UV line emission, and broadband x-ray fluxes with observed values. One dimensional numerical hydrodynamical calculations including the effects of radiative cooling are also presented.

  10. A Search for TeV Gamma-Ray Emission from High-Peaked Flat Spectrum Radio Quasars Using the Whipple Air-Cherenkov Telescope

    CERN Document Server

    Falcone, A D; Boyle, P J; Bradbury, S M; Buckley, J H; Carter-Lewis, D A; Celik, O; Cui, W; Dowdall, C; Duke, C; Fegan, D J; La Perez, I C; Fegan, S J; Finley, J P; Fortson, L F; Gaidos, J A; Gibbs, K; Gammell, S; Hall, J; Hall, T A; Hillas, A M; Holder, J; Horan, D; Jordan, M; Kertzman, M; Kieda, D; Kildea, J; Knapp, J; Kosack, K; Krawczynski, H; Krennrich, F; Le Bohec, S; Linton, E T; Lloyd-Evans, J; Moriarty, P; Müller, D; Nagai, T N; Ong, R A; Page, M; Pallassini, R; Petry, D; Power-Mooney, B; Quinn, J; Rebillot, P; Reynolds, P T; Rose, H J; Schroedter, M; Sembroski, G H; Swordy, S P; Vasilev, V V; Wakely, S P; Walker, G; Weekes, T C

    2004-01-01

    Blazars have traditionally been separated into two broad categories based upon their optical emission characteristics; BL Lacs, with faint or no emission lines, and flat spectrum radio quasars (FSRQs) with prominent, broad emission lines. The spectral energy distribution of FSRQs has generally been thought of as being more akin to the low-peaked BL Lacs, which exhibit a peak in the infrared region of the spectrum, as opposed to high-peaked BL Lacs (HBLs), which exhibit a peak in UV/X-ray region of the spectrum. All blazars currently confirmed as sources of TeV emission are HBLs. Recent surveys have found several FSRQs exhibiting spectral properties similar to HBLs, particularly the synchrotron peak frequency. These objects are potential sources of TeV emission according to several models of blazar jet emission and blazar evolution. Measurements of TeV flux or upper limits could impact existing theories explaining the links between different blazar types and could have a significant impact on our understanding...

  11. X-ray irradiated protoplanetary disk atmospheres I: Predicted emission line spectrum and photoevaporation

    CERN Document Server

    Ercolano, Barbara; Raymond, John C; Clarke, Cathie C

    2008-01-01

    We present MOCASSIN 2D photoionisation and dust radiative transfer models of a prototypical T Tauri disk irradiated by X-rays from the young pre-main sequence star. The calculations demonstrate a layer of hot gas reaching temperatures of ~10^6 K at small radii and ~10^4 K at a distance of 1 AU. The gas temperatures decrease sharply with depth, but appear to be completely decoupled from dust temperatures down to a column depth of ~5*10^21 cm^-2. We predict that several fine-structure and forbidden lines of heavy elements, as well as recombination lines of hydrogen and helium, should be observable with current and future instrumentation, although optical lines may be smothered by the stellar spectrum. Predicted line luminosities are given for the the brightest collisionally excited lines (down to ~10^-8L_sun, and for recombination transitions from several levels of HI and HeI. The mass loss rate due to X-ray photoevaporation estimated from our models is of the order of 10^-8 M_sun yr^-1, implying a dispersal ti...

  12. Orbital parameters and variability of the emission spectrum for the massive binary system 103 Tau

    Science.gov (United States)

    Tarasov, A. E.

    2016-09-01

    Based on high-resolution spectra taken near the He I 6678 Å line for the massive binary system 103 Tau, we have detected a weak absorption component belonging to the binary's secondary component. We have measured the radial velocities of both components, improved the previously known orbital parameters, and determined the new ones. The binary has an orbital period P orb = 58.305d, an orbital eccentricity e = 0.277, a radial velocity semi-amplitude of the bright component K A = 44.8 km s-1, and a component mass ratio M A / M B = 1.77. The absence of photometric variability and the estimates of physical parameters for the primary component suggest that the binary most likely has a considerable inclination of the orbital plane to the observer, i ≈ 50°-60°. In this case, the secondary component is probably a normal dwarf of spectral type B5-B8. Based on the spectra taken near the H α line, we have studied the variability of the emission profile. It is shown to be formed in the Roche lobe of the secondary component, but no traces of active mass exchange in the binary have been detected.

  13. Analysis Of The ATV1 Re-Entry Using Near-UV Spectroscopic Data From The ESA/NASA Multi-Instrument Aircraft Observation Campaign

    Science.gov (United States)

    Lohle, Stefan; Marynowski, Thomas; Knapp, Andreas; Wernitz, Ricarda; Lips, Tobias

    2011-05-01

    The first Automated Transfer Vehicle (ATV1) named Jules Verne was launched in March 2009 to carry over seven tons of experiments, fuel, water, food and other supplies to the International Space Station (ISS) orbiting at about 350 km. Attached to the ISS, it served as an extension to the space station, giving extra space for the six astronauts and cosmonauts who will ultimately form the permanent ISS Crew. On September 29, 2009, a controlled de-orbit maneuver lead the spacecraft to enter the Earth's atmosphere over the south pacific ocean. The following destructive re-entry was observed by two aircraft equipped with a wide variety of imaging and spectroscopic instruments. In this paper, we present quantitative results from the near-UV spectroscopic measurements acquired aboard an experimental DC-8 aircraft operated by NASA. The wavelength range of observation allows a determination of temperatures from radiation and the investigation of atomic radiation with respect to the identification of the destructive process. Furthermore, the excitation temperatures of chromium give an insight into the explosive events occurring during re-entry. Analysing the continuum of the measured spectra, the Planck radiation temperature is fitted to the data. These temperatures indicate that most of the radiating parts are titanium alloys, i.e. the outer structure of ATV1. All results within this paper are compared to a simulated break-up scenario and related to basic results from other experimenters which allows drawing an overall scenario for this destructive re-entry.

  14. The design and development of a high-resolution visible-to-near-UV telescope for balloon-borne astronomy: SuperBIT

    CERN Document Server

    Romualdez, L Javier; Clark, Paul; Damaren, Christopher J; Eifler, Tim; Fraisse, Aurelien A; Galloway, Mathew N; Hartley, John W; Jones, William C; Li, Lun; Lipton, Leeav; Luu, Thuy Vy T; Massey, Richard J; Netterfield, C Barth; Padilla, Ivan; Rhodes, Jason D; Schmoll, Jürgen

    2016-01-01

    Balloon-borne astronomy is unique in that it allows for a level of image stability, resolution, and optical backgrounds that are comparable to space-borne systems due to greatly reduced atmospheric interference, but at a fraction of the cost and over a significantly reduced development time-scale. Instruments operating within visible-to-near-UV bands ($300$ - $900$ um) can achieve a theoretical diffraction limited resolution of $0.01"$ from the stratosphere ($35$ - $40$ km altitude) without the need for extensive adaptive optical systems required by ground-based systems. The {\\it Superpressure Balloon-borne Imaging Telescope} ("SuperBIT") is a wide-field imager designed to achieve 0.02$"$ stability over a 0.5$^\\circ$ field-of-view, for deep single exposures of up to 5 minutes. SuperBIT is thus well-suited for many astronomical observations, from solar or extrasolar planetary observations, to resolved stellar populations and distant galaxies (whether to study their morphology, evolution, or gravitational lensi...

  15. Residual structures in the unfolded state of starch-binding domain of glucoamylase revealed by near-UV circular dichroism and protein engineering techniques.

    Science.gov (United States)

    Ota, Chiaki; Ikeguchi, Masamichi; Tanaka, Akiyoshi; Hamada, Daizo

    2016-10-01

    Protein folding is a thermodynamic process driven by energy gaps between the native and unfolded states. Although a wealth of information is available on the structure of folded species, there is a paucity of data on unfolded species. Here, we analyzed the structural properties of the unfolded state of the starch-binding domain of glucoamylase from Aspergillus niger (SBD) formed in the presence of guanidinium hydrochloride (GuHCl). Although far-UV CD and intrinsic tryptophan fluorescence spectra as well as small angle X-ray scattering suggested that SBD assumes highly unfolded structures in the presence of GuHCl, near-UV circular dichroism of wild-type SBD suggested the presence of residual structures in the unfolded state. Analyses of the unfolded states of tryptophan mutants (W543L, W563A, W590A and W615L) using Similarity Parameter, a modified version of root mean square deviation as a measure of similarity between two spectra, suggested that W543 and W563 have preferences to form native-like residual structures in the GuHCl-unfolded state. In contrast, W615 was entirely unstructured, while W590 tended to form non-native ordered structures in the unfolded state. These data and the amino acid sequence of SBD suggest that local structural propensities in the unfolded state can be determined by the probability of the presence of hydrophobic or charged residues nearby tryptophan residues. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Broad-band transmission spectrum and K-band thermal emission of WASP-43b as observed from the ground

    Science.gov (United States)

    Chen, G.; van Boekel, R.; Wang, H.; Nikolov, N.; Fortney, J. J.; Seemann, U.; Wang, W.; Mancini, L.; Henning, Th.

    2014-03-01

    Aims: WASP-43b is the closest-orbiting hot Jupiter, and it has high bulk density. It causes deep eclipse depths in the system's light curve in both transit and occultation that is attributed to the cool temperature and small radius of its host star. We aim to secure a broad-band transmission spectrum and to detect its near-infrared thermal emission in order to characterize its atmosphere. Methods: We observed one transit and one occultation event simultaneously in the g', r', i', z', J, H, K bands using the GROND instrument on the MPG/ESO 2.2-m telescope, where the telescope was heavily defocused in staring mode. After modeling the light curves, we derived wavelength-dependent transit depths and flux ratios and compared them to atmospheric models. Results: From the transit event, we have independently derived WASP-43's system parameters with high precision and improved the period to be 0.81347437(13) days based on all the available timings. No significant variation in transit depths is detected, with the largest deviations coming from the i'-, H-, and K-bands. Given the observational uncertainties, the broad-band transmission spectrum can be explained by either (i) a flat featureless straight line that indicates thick clouds; (ii) synthetic spectra with absorption signatures of atomic Na/K, or molecular TiO/VO that in turn indicate cloud-free atmosphere; or (iii) a Rayleigh scattering profile that indicates high-altitude hazes. From the occultation event, we detected planetary dayside thermal emission in the K-band with a flux ratio of 0.197 ± 0.042%, which confirms previous detections obtained in the 2.09 μm narrow band and KS-band. The K-band brightness temperature 1878+108-116 K favors an atmosphere with poor day- to nightside heat redistribution. We also have a marginal detection in the i'-band (0.037+0.023-0.021%), corresponding to TB = 2225+139-225 K, which is either a false positive, a signature of non-blackbody radiation at this wavelength, or an

  17. Ion gyro-harmonic structuring in the stimulated radiation spectrum and optical emissions during electron gyro-harmonic heating

    Science.gov (United States)

    Mahmoudian, A.; Scales, W. A.; Bernhardt, P. A.; Samimi, A.; Kendall, E.; Ruohoniemi, J. M.; Isham, B.; Vega-Cancel, O.; Bordikar, M.

    2013-03-01

    Stimulated electromagnetic emissions (SEEs) are secondary radiation produced during active space experiments in which the ionosphere is actively heated with high power high frequency (HF) ground-based radio transmitters. Recently, there has been significant interest in ion gyro-harmonic structuring the SEE spectrum due to the potential for new diagnostic information available such as electron acceleration and creation of artificial ionization layers. These relatively recently discovered gyro-harmonic spectral features have almost exclusively been studied when the transmitting frequency is near the second electron gyro-harmonic frequency. The first extensive systematic experimental investigations of the possibility of these spectral features for third electron gyro-harmonic heating are provided here. Discrete spectral features shifted from the transmit frequency ordered by harmonics of the ion gyro-frequency were observed for third electron gyro-harmonic heating for the first time at a recent campaign at the High Frequency Active Auroral Research Program (HAARP) facility. These features were also closely correlated with a broader band feature at a larger frequency shift from the transmit frequency known as the downshifted peak (DP). The power threshold of these spectral features was measured, as well as their behavior with heater beam angle, and proximity of the transmit frequency to the third electron gyro-harmonic frequency. Comparisons were also made with similar spectral features observed during second electron gyro-harmonic heating during the same campaign. A theoretical model is provided that interprets these spectral features as resulting from parametric decay instabilities in which the pump field ultimately decays into high frequency upper hybrid/electron Bernstein and low frequency neutralized ion Bernstein IB and/or obliquely propagating ion acoustic waves at the upper hybrid interaction altitude. Coordinated optical and SEE observations were carried out

  18. Emissions of Escherichia coli Carrying Extended-Spectrum β-Lactamase Resistance from Pig Farms to the Surrounding Environment

    Directory of Open Access Journals (Sweden)

    Lili Gao

    2015-04-01

    Full Text Available The dissemination of extended-spectrum β-lactamase (ESBL-producing Escherichia coli (E. coli from food-producing animals to the surrounding environment has attracted much attention. To determine the emissions of ESBL-producing E. coli from pig farms to the surrounding environment, fecal and environmental samples from six pig farms were collected. In total, 119 ESBL-producing E. coli were isolated from feces, air samples, water, sludge and soil samples. Antibiotic susceptibility testing showed that the ESBL-producing isolates were resistant to multiple antibiotics and isolates of different origin within the same farm showed similar resistance phenotypes. Both CTX-M and TEM ESBL-encoding genes were detected in these isolates. CTX-M-14 and CTX-M-15 were the predominant ESBL genes identified. ESBL producers from feces and environmental samples within the same farm carried similar CTX-M types. The results indicated that the ESBL-producing E. coli carrying multidrug resistance could readily disseminate to the surrounding environment.

  19. Broad-band transmission spectrum and K-band thermal emission of WASP-43b as observed from the ground

    CERN Document Server

    Chen, Guo; Wang, Hongchi; Nikolov, Nikolay; Fortney, Jonathan J; Seemann, Ulf; Wang, Wei; Mancini, Luigi; Henning, Thomas

    2014-01-01

    (Abridged) We observed one transit and one occultation of the hot Jupiter WASP-43b simultaneously in the g'r'i'z'JHK bands using the GROND instrument on the MPG/ESO 2.2-meter telescope. From the transit event, we have independently derived WASP-43's system parameters with high precision, and improved the period to be 0.81347437(13) days. No significant variation in transit depths is detected, with the largest deviations coming from the i', H, and K bands. Given the observational uncertainties, the broad-band transmission spectrum can be explained by either a flat featureless straight line that indicates thick clouds, synthetic spectra with absorption signatures of atomic Na/K or molecular TiO/VO that indicate cloud-free atmosphere, or a Rayleigh scattering profile that indicates high-altitude hazes. From the occultation event, we have detected planetary dayside thermal emission in the K-band with a flux ratio of 0.197 +/- 0.042%, which confirms previous detections obtained in the 2.09 micron narrow band and K...

  20. The prospects of measuring the angular power spectrum of the diffuse Galactic synchrotron emission with SKA1 Low

    CERN Document Server

    Ali, Sk Saiyad; Choudhuri, Samir; Ghosh, Abhik; Roy, Nirupam

    2016-01-01

    The diffuse Galactic syncrotron emission (DGSE) is the most important diffuse foreground component for future cosmological 21-cm observations. The DGSE is also an important probe of the cosmic ray electron and magnetic field distributions in the turbulent interstellar medium (ISM) of our Galaxy. In this paper we briefly review the Tapered Gridded Estimator (TGE) which can be used to quantify the angular power spectrum of the sky signal directly from the visibilities measured in radio-interferometric observations. The salient features of the TGE are (1.) it deals with the gridded data which makes it computationally very fast (2.) it avoids a positive noise bias which normally arises from the system noise inherent to the visibility data, and (3.) it allows us to taper the sky response and thereby suppresses the contribution from unsubtracted point sources in the outer parts and the sidelobes of the antenna beam pattern. We also summarize earlier work where the TGE was used to measure the C_l of the DGSE using 1...

  1. Background dust emission following grassland fire: a snapshot across the particle-size spectrum highlights how high-resolution measurements enhance detection

    Energy Technology Data Exchange (ETDEWEB)

    Whicker, Jeffrey J [Los Alamos National Laboratory; Martin, Luis M [UNIV OF ARIZONA; Field, Jason P [UNIV OF ARIZONA; Villegas, Juan C [UNIV OF ARIZONA; Brehsears, David D [UNIV OF ARIZONA; Law, Darin J [UNIV OF ARIZONA; Urgeghe, Anna M [UNIV OF ARIZONA

    2009-01-01

    Dust emission rates vary temporally and with particle size. Many studies of dust emission focus on a particular temporal scale and the portion of the particle-size spectrum associated with a single instrument; fewer studies have assessed dust emission across the particle-size spectrum and associated temporal scales using multiple instruments. Particularly lacking are measurements following disturbances such as fire that are high-resolution and focused on finer particles - those with direct implications for human health and potential for long-distance biogeochemical transport - during less windy but more commonly occurring background conditions. We measured dust emissions in unburned and burned semiarid grassland using four different instruments spanning different combinations of temporal resolution and particle-size spectrum: Big Springs Number Eight (BSNE) and Sensit instruments for larger saltating particles, DustTrak instruments for smaller suspended particles, and Total Suspended Particulate (TSP) samplers for measuring the entire range of particle sizes. Unburned and burned sites differed in vegetation cover and aerodynamic roughness, yet surprisingly differences in dust emission rates were only detectable for saltation using BSNE and for smaller aerosols using DustTrak. Our results, surprising in the lack of consistently detected differences, indicate that high-resolution DustTrak measurements offered the greatest promise for detecting differences in background emission rates and that BSNE samplers, which integrate across height, were effective for longer intervals. More generally, our results suggest that interplay between particle size, temporal resolution, and integration across time and height can be complex and may need to be considered more explicitly for effective sampling for background dust emissions.

  2. The role of cloud contamination, aerosol layer height and aerosol model in the assessment of the OMI near-UV retrievals over the ocean

    Science.gov (United States)

    Gassó, Santiago; Torres, Omar

    2016-07-01

    Retrievals of aerosol optical depth (AOD) at 388 nm over the ocean from the Ozone Monitoring Instrument (OMI) two-channel near-UV algorithm (OMAERUV) have been compared with independent AOD measurements. The analysis was carried out over the open ocean (OMI and MODerate-resolution Imaging Spectrometer (MODIS) AOD comparisons) and over coastal and island sites (OMI and AERONET, the AErosol RObotic NETwork). Additionally, a research version of the retrieval algorithm (using MODIS and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) information as constraints) was utilized to evaluate the sensitivity of the retrieval to different assumed aerosol properties. Overall, the comparison resulted in differences (OMI minus independent measurements) within the expected levels of uncertainty for the OMI AOD retrievals (0.1 for AOD 0.3). Using examples from case studies with outliers, the reasons that led to the observed differences were examined with specific purpose to determine whether they are related to instrument limitations (i.e., pixel size, calibration) or algorithm assumptions (such as aerosol shape, aerosol height). The analysis confirms that OMAERUV does an adequate job at rejecting cloudy scenes within the instrument's capabilities. There is a residual cloud contamination in OMI pixels with quality flag 0 (the best conditions for aerosol retrieval according to the algorithm), resulting in a bias towards high AODs in OMAERUV. This bias is more pronounced at low concentrations of absorbing aerosols (AOD 388 nm ˜ distribution, aerosol height, particle shape). It was found that the spherical shape assumption for dust in the current retrieval is the main cause of the underestimate. In addition, it is demonstrated in an example how an incorrect assumption of the aerosol height can lead to an underestimate. Nevertheless, this is not as significant as the effect of particle shape. These findings will be incorporated in a future version of the retrieval algorithm.

  3. Clouds on the hot Jupiter HD189733b: Constraints from the reflection spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Barstow, J. K.; Aigrain, S.; Irwin, P. G. J.; Hackler, T.; Fletcher, L. N. [Department of Physics, University of Oxford, Oxford (United Kingdom); Lee, J. M. [Institute for Theoretical Physics, University of Zürich, CH-8057 Zürich (Switzerland); Gibson, N. P., E-mail: jo.barstow@astro.ox.ac.uk [European Southern Observatory, D-85748 Garching bei München (Germany)

    2014-05-10

    The hot Jupiter HD 189733b is probably the best studied of the known extrasolar planets, with published transit and eclipse spectra covering the near UV to mid-IR range. Recent work on the transmission spectrum has shown clear evidence for the presence of clouds in its atmosphere, which significantly increases the model atmosphere parameter space that must be explored in order to fully characterize this planet. In this work, we apply the NEMESIS atmospheric retrieval code to the recently published HST/STIS reflection spectrum, and also to the dayside thermal emission spectrum in light of new Spitzer/IRAC measurements, as well as our own re-analysis of the HST/NICMOS data. We first use the STIS data to place some constraints on the nature of clouds on HD 189733b and explore solution degeneracy between different cloud properties and the abundance of Na in the atmosphere; as already noted in previous work, absorption due to Na plays a significant role in determining the shape of the reflection spectrum. We then perform a new retrieval of the temperature profile and abundances of H{sub 2}O, CO{sub 2}, CO, and CH{sub 4} from the dayside thermal emission spectrum. Finally, we investigate the effect of including cloud in the model on this retrieval process. We find that the current quality of data does not warrant the extra complexity introduced by including cloud in the model; however, future data are likely to be of sufficient resolution and signal-to-noise that a more complete model, including scattering particles, will be required.

  4. Prospects of Measuring the Angular Power Spectrum of the Diffuse Galactic Synchrotron Emission with SKA1 Low

    Indian Academy of Sciences (India)

    Sk. Saiyad Ali; Somnath Bharadwaj; Samir Choudhuri; Abhik Ghosh; Nirupam Roy

    2016-12-01

    The Diffuse Galactic Syncrotron Emission (DGSE) is the most important diffuse foreground component for future cosmological 21-cm observations. The DGSE is also an important probe of the cosmic ray electron and magnetic field distributions in the turbulent interstellar medium (ISM) of our galaxy. In this paper we briefly review the Tapered Gridded Estimator (TGE) which can be used to quantify the angular power spectrum $C_\\ell$ of the sky signal directly from the visibilities measured in radio-interferometric observations. The salient features of the TGE are: (1) it deals with the gridded data which makes it computationally very fast, (2) it avoids a positive noise bias which normally arises from the system noise inherent to the visibility data, and (3) it allows us to taper the sky response and thereby suppresses the contribution from unsubtracted point sources in the outer parts and the side lobes of the antenna beam pattern. We also summarize earlier work where the TGE was used to measure the $C_\\ell$ of the DGSE using 150 MHz GMRT data. Earlier measurements of $C_\\ell$ are restricted to $\\ell \\le \\ell _{\\max } \\sim 10^{3}$ for the DGSE, the signal at the larger $\\ell$ values is dominated by the residual point sources after source subtraction. The higher sensitivity of the upcoming SKA1 Low will allow the point sources to be subtracted to a fainter level than possible with existing telescopes. We predict that it will be possible to measure the $C_\\ell$ of the DGSE to larger values of $\\ell _{\\max }$ with SKA1 Low. Our results show that it should be possible to achieve $\\ell _{\\max }\\sim 10^{4}$ and $∼10^5$ with 2 minutes and 10 hours of observations respectively.

  5. Prospects of Measuring the Angular Power Spectrum of the Diffuse Galactic Synchrotron Emission with SKA1 Low

    Science.gov (United States)

    Ali, Sk. Saiyad; Bharadwaj, Somnath; Choudhuri, Samir; Ghosh, Abhik; Roy, Nirupam

    2016-12-01

    The Diffuse Galactic Syncrotron Emission (DGSE) is the most important diffuse foreground component for future cosmological 21-cm observations. The DGSE is also an important probe of the cosmic ray electron and magnetic field distributions in the turbulent interstellar medium (ISM) of our galaxy. In this paper we briefly review the Tapered Gridded Estimator (TGE) which can be used to quantify the angular power spectrum C ℓ of the sky signal directly from the visibilities measured in radio-interferometric observations. The salient features of the TGE are: (1) it deals with the gridded data which makes it computationally very fast, (2) it avoids a positive noise bias which normally arises from the system noise inherent to the visibility data, and (3) it allows us to taper the sky response and thereby suppresses the contribution from unsubtracted point sources in the outer parts and the side lobes of the antenna beam pattern. We also summarize earlier work where the TGE was used to measure the C ℓ of the DGSE using 150 MHz GMRT data. Earlier measurements of C ℓ are restricted to ℓ ≤ ℓ _{max } ˜ 103 for the DGSE, the signal at the larger ℓ values is dominated by the residual point sources after source subtraction. The higher sensitivity of the upcoming SKA1 Low will allow the point sources to be subtracted to a fainter level than possible with existing telescopes. We predict that it will be possible to measure the C ℓ of the DGSE to larger values of ℓ _{max } with SKA1 Low. Our results show that it should be possible to achieve ℓ _{max }˜ 104 and ˜105 with 2 minutes and 10 hours of observations respectively.

  6. The variable 6307A emission line in the spectrum of Eta Carinae: blueshifted [S III] 6313A from the interacting winds

    CERN Document Server

    Gull, T R

    2009-01-01

    The 6307A emission line in the spectrum of Eta Car (Martin et al. 2006) is blue-shifted [S III] 6313A emission originating from the outer wind structures of the massive binary system. We realized the identfication while analyzing multiple forbidden emission lines not normally seen in the spectra of massive stars. The high spatial and moderate spectral resolutions of HST/STIS resolve forbidden lines of Fe+, N+, Fe++, S++, Ne++ and Ar++ into spatially and velocity-resolved rope-like features originating from collisionally-excited ions photo-ionized by UV photons or collisions. While the [Fe II] emission extends across a velocity range of +/-500 km/s out to 0."7, more highly ionized forbidden emissions are systematically blue-shifted (-500 to +200 km/s) and extend only to 0."4. The [Fe II] defines the outer regions of the massive primary wind. The [N II], [Fe III] emission define the the outer wind interaction regions directly photo-ionized by far-UV radiation. Variations in emission of [S III] 9533A, 9071A and ...

  7. Visible part of the multiline electronic-vibro-rotational emission spectrum of the $D_2$ molecule measured with moderate resolution. I. Experimental technique and data processing

    CERN Document Server

    Lavrov, B P

    2013-01-01

    The visible part ($\\approx 419 \\div 696$ nm) of the multiline electronic-vibro-rotational emission spectrum of the $D_2$ molecule was recorded with moderate resolution mainly limited by Doppler broadening of spectral lines (line widths $FWHM \\approx 0.013$ nm). After numerical deconvolution of the recorded intensity distributions and proper calibration of the spectrometer the new set of wavenumber values was obtained.

  8. Site Evaluation and RFI spectrum measurements in Portugal at the frequency range 0.408-10 GHz for a GEM polarized galactic radio emission experiment

    CERN Document Server

    Fonseca, R; Cupido, L; dos Santos, D M; Smoot, G F; Tello, C A S

    2004-01-01

    We probed for Radio Frequency Interference (RFI) for the three potential Galactic Emission Mapping Experiment (GEM) sites at Portugal using custom made omnidirectional disconic antennas. For the installation of a 10-meter dish dedicated to the mapping of Polarized Galactic Emission foreground planned for 2005-2007 in the 5-10 GHz band, the three sites chosen as suitable to host the antenna were surveyed for local radio pollution in the frequency range [0.01-10] GHz. Tests were done to look for radio broadcasting and mobile phone emission lines in the radio spectrum. The results show one of the sites to be almost entirely RFI clean and showing good conditions to host the experiment.

  9. A flat-spectrum candidate for a track-type high-energy neutrino emission event, the case of blazar PKS 0723-008

    Science.gov (United States)

    Kun, E.; Biermann, P. L.; Gergely, L. Á.

    2017-03-01

    By cross-correlating both the Parkes Catalogue and the Second Planck Catalogue of Compact Sources with the arrival direction of the track-type neutrinos detected by the IceCube Neutrino Observatory, we find the flat-spectrum blazar PKS 0723-008 as a good candidate for the high-energy neutrino event 5 (ID5). Apart from its coordinates matching those of ID5, PKS 0723-008 exhibits further interesting radio properties. Its spectrum is flat up to high Planck frequencies, and it produced a fivefold-increased radio flux density through the last decade. Based upon these radio properties we propose a scenario of binary black hole evolution leading to the observed high-energy neutrino emission. The main contributing events are the spin-flip of the dominant black hole, the formation of a new jet with significant particle acceleration and interaction with the surrounding material, with the corresponding increased radio flux. Doppler boosting from the underlying jet pointing to the Earth makes it possible to identify the origin of the neutrinos, so the merger itself is the form of an extended flat-spectrum radio emission, a key selection criterion to find traces of this complex process.

  10. Experimental studies on the neutron emission spectrum and induced radioactivity of the sup 7 Li(d,n) reaction in the 20-40 MeV region

    CERN Document Server

    Baba, M; Hagiwara, M; Sugimoto, M; Miura, T; Kawata, N; Yamadera, A; Orihara, H

    2002-01-01

    To improve the data accuracy of the neutron emission spectrum of the sup 7 Li(d,n) reaction and the radioactivity ( sup 7 Be, sup 3 H, etc.) accumulated in the sup 7 Li target in IFMIF, we have measured the neutron emission spectrum and the radioactivity of sup 7 Be induced in the lithium target for 25 MeV deuterons at the Tohoku University AVF cyclotron (K=110) facility. Neutron spectra were measured with the time-of-flight (TOF) method at four laboratory angles by using a beam swinger system and a well collimated TOF channel. Induced radioactivity was measured by detecting the gamma-rays from sup 7 Be with a pure Ge detector. Experimental results are compared with other experimental data. The present result of neutron emission spectra are in qualitative agreement with other experimental data but that of sup 7 Be production was much larger than expected by the recent codes. Measurement will be extended to several incident energies up to 40 MeV.

  11. Experimental studies on the neutron emission spectrum and induced radioactivity of the {sup 7}Li(d,n) reaction in the 20-40 MeV region

    Energy Technology Data Exchange (ETDEWEB)

    Baba, M. E-mail: babam@cyric.tohoku.ac.jp; Aoki, T.; Hagiwara, M.; Sugimoto, M.; Miura, T.; Kawata, N.; Yamadera, A.; Orihara, H

    2002-12-01

    To improve the data accuracy of the neutron emission spectrum of the {sup 7}Li(d,n) reaction and the radioactivity ({sup 7}Be, {sup 3}H, etc.) accumulated in the {sup 7}Li target in IFMIF, we have measured the neutron emission spectrum and the radioactivity of {sup 7}Be induced in the lithium target for 25 MeV deuterons at the Tohoku University AVF cyclotron (K=110) facility. Neutron spectra were measured with the time-of-flight (TOF) method at four laboratory angles by using a beam swinger system and a well collimated TOF channel. Induced radioactivity was measured by detecting the gamma-rays from {sup 7}Be with a pure Ge detector. Experimental results are compared with other experimental data. The present result of neutron emission spectra are in qualitative agreement with other experimental data but that of {sup 7}Be production was much larger than expected by the recent codes. Measurement will be extended to several incident energies up to 40 MeV.

  12. Modification and control of coherence effects in the spontaneous emission spectrum of a three-level atom at weak field regime

    Science.gov (United States)

    Dutta, Bibhas Kumar; Panchadhyayee, Pradipta

    2016-09-01

    It has been shown that coherence effects have a marked influence in the spontaneous emission spectrum of a three-level Λ -type atom driven by weak coherent and incoherent fields. Phase dependent evolution of interference effects leading to spectral narrowing, generation of spectral hole and dark line are exhibited in the present scheme when the atom does not interact with the incoherent fields. The basic mechanism underlying this scheme seems to be appropriate for a phaseonium. Apart from phase-coherence introduced in the system the phenomenon of line narrowing, in the presence of weak incoherent pumping, can be achieved in a different way as a consequence of two competitive resonant effects: sharp non-Lorentzian and symmetric Fano-like-resonance contributions to the line shape. In both the situations, the evolution of narrow structures in the line shape can be achieved even when the emission is influenced by the dephasing of Raman coherence.

  13. Commentary Relative to the Emission Spectrum of the Solar Atmosphere: Further Evidence for a Distinct Solar Surface

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2013-07-01

    Full Text Available The chromosphere and corona of the Sun represent tenuous regions which are characterized by numerous optically thin emission lines in the ultraviolet and X-ray bands. When observed from the center of the solar disk outward, these emission lines experience modest brightening as the limb is approached. The intensity of many ultraviolet and X-ray emission lines nearly doubles when observation is extended just beyond the edge of the disk. These findings indicate that the solar body is opaque in this frequency range and that an approximately two fold greater region of the solar atmosphere is being sampled outside the limb. These observations provide strong support for the presence of a distinct solar surface. Therefore, the behavior of the emission lines in this frequency range constitutes the twenty fifth line of evidence that the Sun is comprised of condensed matter

  14. Simultaneous physical retrieval of surface emissivity spectrum and atmospheric parameters from infrared atmospheric sounder interferometer spectral radiances.

    Science.gov (United States)

    Masiello, Guido; Serio, Carmine

    2013-04-10

    The problem of simultaneous physical retrieval of surface emissivity, skin temperature, and temperature, water-vapor, and ozone atmospheric profiles from high-spectral-resolution observations in the infrared is formulated according to an inverse problem with multiple regularization parameters. A methodology has been set up, which seeks an effective solution to the inverse problem in a generalized L-curve criterion framework. The a priori information for the surface emissivity is obtained on the basis of laboratory data alone, and that for the atmospheric parameters by climatology or weather forecasts. To ensure that we deal with a problem of fewer unknowns than observations, the dimensionality of the emissivity is reduced through expansion in Fourier series. The main objective of this study is to demonstrate the simultaneous retrieval of emissivity, skin temperature, and atmospheric parameters with a two-dimensional L-curve criterion. The procedure has been demonstrated with spectra observed from the infrared atmospheric sounder interferometer, flying onboard the European Meteorological Operational satellite. To check the quality and reliability of the methodology, we have used spectra recorded over regions characterized by known or stable emissivity. These include sea surface, for which effective emissivity models are known, and arid lands (Sahara and Namib Deserts) that are known to exhibit the characteristic spectral signature of quartz-rich sand.

  15. Hubble Space Telescope Transmission Spectroscopy of the Exoplanet HD 189733b: High-altitude atmospheric haze in the optical and near-UV with STIS

    CERN Document Server

    Sing, D K; Aigrain, S; Charbonneau, D; Desert, J -M; Gibson, N; Gilliland, R; Hayek, W; Henry, G; Knutson, H; Etangs, A Lecavelier des; Mazeh, T; Tal-Or, L

    2011-01-01

    We present Hubble Space Telescope optical and near-ultraviolet transmission spectra of the transiting hot-Jupiter HD189733b, taken with the repaired Space Telescope Imaging Spectrograph (STIS) instrument. The resulting spectra cover the range 2900-5700 Ang and reach per-exposure signal-to-noise levels greater than 11,000 within a 500 Ang bandwidth. We used time series spectra obtained during two transit events to determine the wavelength dependance of the planetary radius and measure the exoplanet's atmospheric transmission spectrum for the first time over this wavelength range. Our measurements, in conjunction with existing HST spectra, now provides a broadband transmission spectrum covering the full optical regime. We find a planetary transmission spectrum in good agreement with that of Rayleigh scattering from a high-altitude atmospheric haze as previously found from HST ACS camera. The STIS data also shows unambiguous evidence of a large occulted stellar spot during one of our transit events, which we use...

  16. Broad-band spectrophotometry of the hot Jupiter HAT-P-12b from the near-UV to the near-IR

    CERN Document Server

    Mallonn, M; Weingrill, J; von Essen, C; Strassmeier, K G; Piotto, G; Pagano, I; Scandariato, G; Csizmadia, Sz; Herrero, E; Sada, P V; Dhillon, V S; Marsh, T R; Künstler, A; Bernt, I; Granzer, T

    2015-01-01

    The detection of trends or gradients in the transmission spectrum of extrasolar planets is possible with observations at very low spectral resolution. Transit measurements of sufficient accuracy using selected broad-band filters allow for an initial characterization of the atmosphere of the planet. We obtained time series photometry of 20 transit events and analyzed them homogeneously, along with eight light curves obtained from the literature. In total, the light curves span a range from 0.35 to 1.25 microns. During two observing seasons over four months each, we monitored the host star to constrain the potential influence of starspots on the derived transit parameters. We rule out the presence of a Rayleigh slope extending over the entire optical wavelength range, a flat spectrum is favored for HAT-P-12b with respect to a cloud-free atmosphere model spectrum. A potential cause of such gray absorption is the presence of a cloud layer at the probed latitudes. Furthermore, in this work we refine the transit pa...

  17. Near-UV and blue wavelength excitable Mg{sub 0.6}Ca{sub 2.16}Mo{sub 0.2}W{sub 0.8}O{sub 6}: Eu{sub 0.12}{sup 3+}/Na{sub 0.12}{sup +} high efficiency red phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Khanna, A. [Smart Lighting Engineering Research Center, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Electrical Computer and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Dutta, P.S., E-mail: duttap@rpi.edu [Smart Lighting Engineering Research Center, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Electrical Computer and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2015-05-15

    Red phosphors with narrow emission around 615 nm (with FWHM~5–10 nm) having chemical compositions of A{sub 0.6}Ca{sub 2.16}Mo{sub 0.2}W{sub 0.8}O{sub 6}: Eu{sub 0.12}{sup 3+}/Na{sub 0.12}{sup +} (A=Mg, Sr) have been found to exhibit the highest luminescence amongst the molybdate–tungstate family when excited by sources in the 380–420 nm wavelength range. Thus they are most suitable for enhancing color rendering index and lowering color temperature in phosphor converted white LEDs (pc-WLEDs) with near-UV/blue LED excitation sources. The excitation band edge in the near UV/blue wavelength in the reported phosphor has been attributed to the coordination environment of the transition metal ion (Mo{sup 6+}, W{sup 6+}) and host crystal structure. Furthermore the quantum efficiency of the phosphors has been enhanced by adjusting activator concentration, suitable compositional alloying using substitutional alkaline earth metal cations and charge compensation mechanisms. - Graphical abstract: The charge transfer excitation of orthorhombic Mg{sub 0.6}Ca{sub 2.16}Mo{sub 0.2}W{sub 0.8}O{sub 6}: Eu{sub 0.12}{sup 3+}/Na{sub 0.12}{sup +} is significantly higher than tetragonal CaMoO{sub 4}: Eu{sup 3+} phosphors making Mg{sub 0.6}Ca{sub 2.16}Mo{sub 0.2}W{sub 0.8}O{sub 6}: Eu{sub 0.12}{sup 3+}/Na{sub 0.12}{sup +} prime candidates for fabrication of warm white phosphor-converted LEDs. - Highlights: • LED excitable Mg{sub 0.6}Ca{sub 2.16}Mo{sub 0.2}W{sub 0.8}O{sub 6}: Eu{sub 0.12}{sup 3+}/Na{sub 0.12}{sup +} phosphors were synthesized. • These phosphors are 10 times more intense than CaMoO{sub 4}: Eu{sup 3+} red phosphors. • Their intensity and efficiency were enhanced by materials optimization techniques. • Such techniques include compositional alloying, charge compensation, etc.

  18. A hard ionizing spectrum in z=3-4 Ly-alpha emitters with intense [OIII] emission: Analogs of galaxies in the reionization era?

    CERN Document Server

    Nakajima, Kimihiko; Iwata, Ikuru; Inoue, Akio; Kusakabe, Haruka; Ouchi, Masami; Robertson, Brant

    2016-01-01

    We present Keck/MOSFIRE spectra of the diagnostic nebular emission lines [OIII]5007,4959, [OII]3727, and H-beta for a sample of 15 redshift z=3.1-3.7 Ly-alpha emitters (LAEs) and Lyman break galaxies (LBGs). In conjunction with spectra from other surveys, we confirm earlier indications that LAEs have a much higher [OIII]/[OII] line ratio than is seen in similar redshift LBGs. By comparing their distributions on a [OIII]/[OII] versus R23 diagram, we demonstrate that this difference cannot arise solely because of their lower metallicities but most likely is due to a harder ionizing spectrum. Using measures of H-beta and recombination theory, we demonstrate, for a subset of our LAEs, that xi_ion - the number of Lyman continuum photons per UV luminosity - is indeed 0.2-0.5 dex larger than for typical LBGs at similar redshifts. Using photoionization models we estimate the effect this would have on both [OIII]/[OII] and R23 and conclude such a hard spectrum can only partially explain such intense line emission. The...

  19. Chirped InAs/InP quantum-dash laser with enhanced broad spectrum of stimulated emission

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-03-01

    We report on the demonstration of 50 nm (full-width at half-maximum) broadband stimulated emission from a chirped AlGaInAs barrier thickness multi-stack InAs/InP quantum dash (Qdash) laser. The 2 ?m wide uncoated Fabry-Perot (FP) ridge-waveguide laser exhibits a total power of 0.18 W, corresponding to an average spectral power density of 3.5 mW/nm, under pulsed current conditions. Intentional extended inhomogeneity across the Qdash stacks have been attributed to the enhancement of broadband emission. © 2013 American Institute of Physics.

  20. Eu{sup 3+} ions co-doped CLPO: Dy{sup 3+} single phase white-light emitting phosphors for near UV-based white LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Yong Il; Bharat, L. Krishna; Yu, Jae Su, E-mail: jsyu@khu.ac.kr

    2015-11-15

    CaLaP{sub 3}O{sub 10}: Dy{sup 3+}/Eu{sup 3+} phosphor powders were prepared by a facile sol–gel method. These samples were thermally treated at 900 °C for 6 h to get monazite type structure with monoclinic unit cell. The phase, morphology and optical properties of phosphor samples were characterized by X-ray diffraction patterns, Fourier transform infrared spectra, scanning/transmission electron microscope images, and photoluminescence excitation and emission spectra. The Dy{sup 3+}/Eu{sup 3+} ions co-doped samples showed warm white-light emissions with lower correlated color temperature values at higher Eu{sup 3+} ion concentrations. The near-ultraviolet (NUV) excitation and the effective energy transfer form Dy{sup 3+} to Eu{sup 3+} ions can make these phosphors as potential candidates for NUV excitation based white light-emitting diodes. - Highlights: • Single crystalline CLPO phosphors were successfully prepared by a sol–gel process. • CLPO has monazite type structure with monoclinic unit cells. • Eu{sup 3+} co-doped CLPO: Dy{sup 3+} samples give warm white-light emission with low CCT values. • The NUV excitation (392 nm) allows the use of this material for WLED applications.

  1. Tracking biochemical changes correlated with ultra-weak photon emission using metabolomics

    NARCIS (Netherlands)

    Burgos, R.C.R.; Cervinková, K.; Laan, T. van der; Ramautar, R.; Wijk, E.P.A. van; Cifra, M.; Koval, S.; Berger, R.; Hankemeier, T.; Greef, J. van der

    2016-01-01

    Ultra-weak photon emission (UPE) is light emitted spontaneously by biological systems without the use of specific luminescent complexes. UPE is emitted in the near-UV/UV–Vis/near-IR spectra during oxidative metabolic reactions; however, the specific pathways involved in UPE remain poorly understood.

  2. Forward and Inverse Modeling of the Emission and Transmission Spectrum of GJ 436b: Investigating Metal Enrichment, Tidal Heating, and Clouds

    CERN Document Server

    Morley, Caroline V; Line, Michael; Fortney, Jonathan J; Thorngren, Daniel; Marley, Mark S; Teal, Dillon; Lupu, Roxana

    2016-01-01

    The Neptune-mass GJ 436b is one of the most-studied transiting exoplanets with repeated measurements of both its thermal emission and transmission spectra. We build on previous studies to answer outstanding questions about this planet, including its potentially high metallicity and tidal heating of its interior. We present new observations of GJ 436b's thermal emission at 3.6 and 4.5 micron, which reduce uncertainties in estimates of GJ 436b's flux at those wavelengths and demonstrate consistency between Spitzer observations spanning more than 7 years. We analyze the Spitzer thermal emission photometry and Hubble WFC3 transmission spectrum in tandem. We use a powerful dual-pronged modeling approach, comparing these data to both self-consistent and retrieval models. We vary the metallicity, intrinsic luminosity from tidal heating, disequilibrium chemistry, and heat redistribution. We also study the effect of clouds and photochemical hazes on the spectra, but do not find strong evidence for either. The self-con...

  3. Planck intermediate results XXX. The angular power spectrum of polarized dust emission at intermediate and high Galactic latitudes

    DEFF Research Database (Denmark)

    Adam, R.; Ade, P. A. R.; Aghanim, N.

    2016-01-01

    The polarized thermal emission from diffuse Galactic dust is the main foreground present in measurements of the polarization of the cosmic microwave background (CMB) at frequencies above 100 GHz. In this paper we exploit the uniqueness of the Planck HFI polarization data from 100 to 353 GHz...... to measure the polarized dust angular power spectra C-l(EE) and C-l(BB) over the multipole range 40 CMB polarization...... dust column densities. We show that even in the faintest dust-emitting regions there are no "clean" windows in the sky where primordial CMB B-mode polarization measurements could be made without subtraction of foreground emission. Finally, we investigate the level of dust polarization in the specific...

  4. Planck intermediate results. XXX. The angular power spectrum of polarized dust emission at intermediate and high Galactic latitudes

    CERN Document Server

    Adam, R; Aghanim, N; Arnaud, M; Aumont, J; Baccigalupi, C; Banday, A J; Barreiro, R B; Bartlett, J G; Bartolo, N; Battaner, E; Benabed, K; Benoit-Lévy, A; Bernard, J -P; Bersanelli, M; Bielewicz, P; Bonaldi, A; Bonavera, L; Bond, J R; Borrill, J; Bouchet, F R; Boulanger, F; Bracco, A; Bucher, M; Burigana, C; Butler, R C; Calabrese, E; Cardoso, J -F; Catalano, A; Challinor, A; Chamballu, A; Chary, R -R; Chiang, H C; Christensen, P R; Clements, D L; Colombi, S; Colombo, L P L; Combet, C; Couchot, F; Coulais, A; Curto, A; Cuttaia, F; Danese, L; Davies, R D; Davis, R J; de Bernardis, P; de Zotti, G; Delabrouille, J; Delouis, J -M; Désert, F -X; Dickinson, C; Diego, J M; Dolag, K; Dole, H; Donzelli, S; Doré, O; Douspis, M; Ducout, A; Dunkley, J; Dupac, X; Efstathiou, G; Elsner, F; Enßlin, T A; Eriksen, H K; Falgarone, E; Finelli, F; Forni, O; Frailis, M; Fraisse, A A; Franceschi, E; Frejsel, A; Galeotta, S; Galli, S; Ganga, K; Ghosh, T; Giard, M; Giraud-Héraud, Y; Gjerløw, E; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Gruppuso, A; Guillet, V; Hansen, F K; Hanson, D; Harrison, D L; Helou, G; Henrot-Versillé, S; Hernández-Monteagudo, C; Herranz, D; Hivon, E; Holmes, W A; Huffenberger, K M; Hurier, G; Jaffe, A H; Jaffe, T R; Jewell, J; Jones, W C; Juvela, M; Keihänen, E; Keskitalo, R; Kisner, T S; Kneissl, R; Knoche, J; Knox, L; Krachmalnicoff, N; Kunz, M; Kurki-Suonio, H; Lagache, G; Lamarre, J -M; Lasenby, A; Lattanzi, M; Lawrence, C R; Leahy, J P; Leonardi, R; Lesgourgues, J; Levrier, F; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maffei, B; Maino, D; Mandolesi, N; Mangilli, A; Maris, M; Martin, P G; Martínez-González, E; Masi, S; Matarrese, S; Mazzotta, P; Melchiorri, A; Mendes, L; Mennella, A; Migliaccio, M; Mitra, S; Miville-Deschênes, M -A; Moneti, A; Montier, L; Morgante, G; Mortlock, D; Moss, A; Munshi, D; Murphy, J A; Naselsky, P; Nati, F; Natoli, P; Netterfield, C B; Nørgaard-Nielsen, H U; Noviello, F; Novikov, D; Novikov, I; Pagano, L; Pajot, F; Paladini, R; Paoletti, D; Partridge, B; Pasian, F; Patanchon, G; Pearson, T J; Perdereau, O; Perotto, L; Perrotta, F; Pettorino, V; Piacentini, F; Piat, M; Pierpaoli, E; Pietrobon, D; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Popa, L; Pratt, G W; Prunet, S; Puget, J -L; Rachen, J P; Reach, W T; Rebolo, R; Remazeilles, M; Renault, C; Renzi, A; Ricciardi, S; Ristorcelli, I; Rocha, G; Rosset, C; Rossetti, M; Roudier, G; d'Orfeuil, B Rouillé; Rubiño-Martín, J A; Rusholme, B; Sandri, M; Santos, D; Savelainen, M; Savini, G; Scott, D; Soler, J D; Spencer, L D; Stolyarov, V; Stompor, R; Sudiwala, R; Sunyaev, R; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Terenzi, L; Tomasi, M; Tristram, M; Tucci, M; Tuovinen, J; Valenziano, L; Valiviita, J; Van Tent, B; Vibert, L; Vielva, P; Villa, F; Wade, L A; Wandelt, B D; Watson, R; Wehus, I K; White, M; White, S D M; Yvon, D; Zacchei, A; Zonca, A

    2016-01-01

    The polarized thermal emission from Galactic dust is the main foreground present in measurements of the polarization of the cosmic microwave background (CMB) at frequencies above 100GHz. We exploit the Planck HFI polarization data from 100 to 353GHz to measure the dust angular power spectra $C_\\ell^{EE,BB}$ over the range $40<\\ell<600$. These will bring new insights into interstellar dust physics and a precise determination of the level of contamination for CMB polarization experiments. We show that statistical properties of the emission can be characterized over large fractions of the sky using $C_\\ell$. For the dust, they are well described by power laws in $\\ell$ with exponents $\\alpha^{EE,BB}=-2.42\\pm0.02$. The amplitudes of the polarization $C_\\ell$ vary with the average brightness in a way similar to the intensity ones. The dust polarization frequency dependence is consistent with modified blackbody emission with $\\beta_d=1.59$ and $T_d=19.6$K. We find a systematic ratio between the amplitudes of ...

  5. The temporal changes in the emission spectrum of Comet 9P/Tempel 1 after Deep Impact

    CERN Document Server

    Jackson, William M; Shi, Xiaoyu; Cochran, Anita L

    2009-01-01

    The time dependence of the changes in the emission spectra of Comet 9P/Tempel 1 after Deep Impact are derived and discussed. This was a unique event because for the first time it gave astronomers the opportunity to follow the time history of the formation and decay of O(1S), OH, CN, C2, C3, NH, and NH2. Least squares fits of a modified Haser model with constraints using known rate constants were fit to the observed data. In the case of OH a simple two-step Haser model provides a reasonable fit to the observations. Fitting the emissions from O(1S), CN, C2, C3, NH, and NH2 requires the addition of a delayed component to a regular two or three step Haser model. From this information a picture of the Deep Impact encounter emerges where there is an initial formation of gas and dust, which is responsible for the prompt emission that occurs right after impact. A secondary source of gas starts later after impact when the initial dust has dissipated enough so that solar radiation can reach the surface of freshly expos...

  6. Fe K Emission and Absorption in the XMM-EPIC Spectrum of the Seyfert Galaxy IC 4329a

    CERN Document Server

    Markowitz, A; Reeves, J

    2006-01-01

    We present a detailed analysis of the XMM-Newton long-look of the Seyfert galaxy IC 4329a. The Fe K bandpass is dominated by two resolved peaks at 6.4 keV and 7.0 keV, consistent with neutral or near-neutral Fe K alpha and K beta emission. There is a prominent redward asymmetry in the 6.4 keV line, which could indicate emission from a Compton shoulder. Alternatively, models using dual relativistic disklines are found to describe the emission profile well. A low-inclination, moderately-relativistic dual-diskline model is possible if the contribution from narrow components, due to distant material, is small or absent. A high-inclination, moderately relativistic profile for each peak is possible if there are roughly equal contributions from both the broad and narrow components. Combining the XMM-Newton data with RXTE monitoring data, we explore the time-resolved spectral behavior on time scales from hours to 2 years. We find no strong evidence for variability of the Fe K line flux on any time scale, likely due t...

  7. THE SPECTRUM OF ISOTROPIC DIFFUSE GAMMA-RAY EMISSION BETWEEN 100 MeV AND 820 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, M.; Buehler, R. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M. [Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634-0978 (United States); Albert, A.; Blandford, R. D.; Bloom, E. D.; Bottacini, E.; Caliandro, G. A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Atwood, W. B. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Baldini, L.; Bellazzini, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d' Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D.; Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bechtol, K. [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Bissaldi, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, and Università di Trieste, I-34127 Trieste (Italy); Brandt, T. J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bregeon, J. [Laboratoire Univers et Particules de Montpellier, Université Montpellier 2, CNRS/IN2P3, F-34095 Montpellier (France); Bruel, P., E-mail: markus.ackermann@desy.de, E-mail: bechtol@kicp.uchicago.edu [Laboratoire Leprince-Ringuet, École Polytechnique, CNRS/IN2P3, F-91128 Palaiseau (France); and others

    2015-01-20

    The γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse γ-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission (DGE), and a longer data accumulation of 50 months allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 ± 0.02 and a break energy of (279 ± 52) GeV using our baseline DGE model. The total intensity attributed to the IGRB is (7.2 ± 0.6) × 10{sup –6} cm{sup –2} s{sup –1} sr{sup –1} above 100 MeV, with an additional +15%/–30% systematic uncertainty due to the Galactic diffuse foregrounds.

  8. Discovery of hard-spectrum \\gamma-ray emission from the BL Lac object 1ES 0414+009

    CERN Document Server

    Abramowski, A; Aharonian, F; Akhperjanian, A G; Anton, G; Balzer, A; Barnacka, A; de Almeida, U Barres; Becherini, Y; Becker, J; Behera, B; Bernlöhr, K; Birsin, E; Biteau, J; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Büsching, I; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Chounet, L -M; Clapson, A C; Coignet, G; Cologna, G; Conrad, J; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubois, F; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Farnier, C; Feinstein, F; Fernandes, M V; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gallant, Y A; Gast, H; Gérard, L; Gerbig, D; Giebels, B; Glicenstein, J F; Glück, B; Goret, P; Göring, D; Häffner, S; Hague, J D; Hampf, D; Hauser, M; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hinton, J A; Hoffmann, A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; de Jager, O C; Jahn, C; Jamrozy, M; Jung, I; Kastendieck, M A; Katarzynski, K; Katz, U; Kaufmann, S; Keogh, D; Khangulyan, D; Khélifi, B; Kluźniak, D Klochkov W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Laffon, H; Lamanna, G; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maurin, D; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Moderski, R; Moulin, E; Naumann, C L; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nekrassov, D; Nguyen, N; Nicholas, B; Niemiec, J; Nolan, S J; Ohm, S; Wilhelmi, E de Ona; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Arribas, M Paz; Pedaletti, G; Pelletier, G; Petrucci, P -O; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Rayner, S M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Ruppel, J; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schöck, F M; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sheidaei, F; Sikora, M; Skilton, J L; Sol, H; Spengler, G; Stawarz, L; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Vialle, J P; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorobiov, S; Vorster, M; Wagner, S J; Ward, M; White, R; Wierzcholska, A; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S; Costamante, L; Fegan, S; Ajello, M

    2012-01-01

    1ES 0414+009 (z = 0.287) is a distant high-frequency-peaked BL Lac object, and has long been considered a likely emitter of very-high energy (VHE, E>100 GeV) gamma-rays due to its high X-ray and radio flux. Observations in the VHE gamma-ray band and across the electromagnetic spectrum can provide insights into the origin of highly energetic particles present in the source and the radiation processes at work. Because of the distance of the source, the gamma-ray spectrum might provide further limits on the level of the Extragalactic Background Light (EBL). We report observations made between October 2005 and December 2009 with H.E.S.S., an array of four imaging atmospheric Cherenkov telescopes. Observations at high energies (HE, 100 MeV - 100 GeV) with the Fermi-LAT instrument in the first 20 months of its operation are also reported. To complete the multi-wavelength picture, archival UV and X-ray observations with the Swift satellite and optical observations with the ATOM telescope are also used. Based on the ...

  9. A multicentre trial of the epilation efficacy of a new, large spot size, constant spectrum emission IPL device.

    Science.gov (United States)

    Ancona, Dvora; Stuve, Ranghild; Trelles, Mario A

    2007-09-01

    This study assesses the efficacy of a new, low fluence, constant spectrum IPL device. In three European centres, 52 females underwent epilation of one arm axilla with the new IPL, the contralateral axilla serving as a treatment control. Satisfied patients at the 1-month assessment received no further treatments and in the other patients up to five further monthly sessions were given. Clinical photography was taken at the pretreatment baseline and at approximately 1 month later. Side effects and hair attributes were graded. Patient satisfaction was graded. All patients completed the study: 11 required one treatment, with eight, 13, 11 and nine requiring two, three, four and five sessions, respectively. Side effects were minimal. A total of 44 patients were very satisfied with the final result, eight were somewhat satisfied and no patient expressed dissatisfaction, giving an overall satisfaction score of 84.6%. In all cases, hair regrowth in the treated side was finer and lighter. The greatest efficacy was seen in coarse dark hair in darker skin, and least efficacy was noted in fine blonde hair in lighter skin. Epilation with this constant spectrum IPL was safe, effective, well tolerated, and with high patient satisfaction. Repeated sessions were required in some patients with lighter hair and skin.

  10. Discovery of hard-spectrum γ-ray emission from the BL Lacertae object 1ES 0414+009

    Science.gov (United States)

    H.E.S.S. Collaboration; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Balzer, A.; Barnacka, A.; Barres de Almeida, U.; Becherini, Y.; Becker, J.; Behera, B.; Bernloehr, K.; Birsin, E.; Biteau, J.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Buesching, I.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Cologna, G.; Conrad, J.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Djannati-Ataie, A.; Domainko, W.; Drury, L. O'c.; Dubois, F.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Foerster, A.; Fuesling, M.; Gallant, Y. A.; Gast, H.; Gerard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J. F.; Glueck, B.; Goret, P.; Goering, D.; Haeffner, S.; Hague, J. D.; Hampf, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jamrozy, M.; Jung, I.; Kastendieck, M. A.; Katarzynski, K.; Katz, U.; Kaufmann, S.; Keogh, D.; Khangulyan, D.; Khelifi, B.; Klochkov, D.; Kluzniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Laffon, H.; Lamanna, G.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, D.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Medina, M. C.; Mehault, J.; Moderski, R.; Moulin, E.; Naumann, C. L.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; de Ona Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Paz Arribas, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Puehlhofer, G.; Punch, M.; Quirrenbach, A.; Raue, M.; Rayner, S. M.; Reimer, A.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schoeck, F. M.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sheidaei, F.; Sikora, M.; Skilton, J. L.; Sol, H.; Spengler, G.; Stawarz, L.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Terrier, R.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Vialle, J. P.; Viana, A.; Vincent, P.; Voelk, H. J.; Volpe, F.; Vorobiov, S.; Vorster, M.; Wagner, S. J.; Ward, M.; White, R.; Wierzcholska, A.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S. L.; Costamante, L.; Fegan, S.; Ajello, M.

    2012-02-01

    Context. 1ES 0414 + 009 (z = 0.287) is a distant high-frequency-peaked BL Lac object, and has long been considered a likely emitter of very-high-energy (VHE, E > 100 GeV) γ-rays due to its high X-ray and radio flux. Aims: Observations in the VHE γ-ray band and across the electromagnetic spectrum can provide insights into the origin of highly energetic particles present in the source and the radiation processes at work. Because of the distance of the source, the γ-ray spectrum might provide further limits on the level of the extragalactic background light (EBL). Methods: We report observations made between October 2005 and December 2009 with H.E.S.S., an array of four imaging atmospheric Cherenkov telescopes. Observations at high energies (HE, 100 MeV-100 GeV) with the Fermi-LAT instrument in the first 20 months of its operation are also reported. To complete the multi-wavelength picture, archival UV and X-ray observations with the Swift satellite and optical observations with the ATOM telescope are also used. Results: Based on the observations with H.E.S.S., 1ES 0414 + 009 is detected for the first time in the VHE band. An excess of 224 events is measured, corresponding to a significance of 7.8σ. The photon spectrum of the source is well described by a power law, with photon index of ΓVHE = 3.45 ± 0.25stat ± 0.20syst. The integral flux above 200 GeV is (1.88 ± 0.20stat ± 0.38syst) × 10-12 cm-2 s-1. Observations with the Fermi-LAT in the first 20 months of operation show a flux between 200 MeV and 100 GeV of (2.3 ± 0.2stat) × 10-9 erg cm-2 s-1, and a spectrum well described by a power-law function with a photon index ΓHE = 1.85 ± 0.18. Swift/XRT observations show an X-ray flux between 2 and 10 keV of (0.8-1) × 10-11 erg cm-2 s-1, and a steep spectrum ΓX = (2.2-2.3). Combining X-ray with optical-UV data, a fit with a log-parabolic function locates the synchrotron peak around 0.1 keV. Conclusions: Although the GeV-TeV observations do not provide better

  11. Investigation on luminescence properties of Eu2+-doped Ba3Al2O5Cl2 phosphor for near-UV-excited white LEDs.

    Science.gov (United States)

    Pawade, V B; Dhoble, S J

    2012-01-01

    Ba3Al2O5Cl2:Eu(2+) phosphor was prepared by combustion synthesis (CS). The prepared phosphor was excited at 329 nm; the phosphors shows an efficient bluish-green wide-band emission centred at 490 nm, which originates from the 4f(6)d(1)  →  4f(7) transition of Eu(2+) ions. The excitation spectra of the phosphors have a band centred at 329 nm. It was also characterized by XRD, FT-IR for confirmation of phase purity, and FT-IR analysis indicated the vibrations of metal-oxygen (M-O) groups. SEM shows the morphology of the phosphor at the submicron scale. The results indicate that Ba3Al2O5Cl2:Eu(2+) phosphor may be applicable for solid-state lighting purposes.

  12. Imaging spectrum and pitfalls of {sup 11}C-methionine position emission tomography in a series of patients with intracranial lesions

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Kimiteru [Dept. of Radiology, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo (Japan); Matsuda, Hiroshi [Integrative Brain Imaging Center, National Center of Neurology and Psychiatry, Tokyo (Japan); Kubota, Kazoo [Div. of Nuclear Medicine, National Center for Global Health and Medicine, Tokyo (Japan)

    2016-06-15

    {sup 11}C-methionine (Met) positron emission tomography (PET) is one of the most commonly used PET tracers for evaluating brain tumors. However, few reports have described tips and pitfalls of {sup 11}C-Met PET for general practitioners. Physiological {sup 11}C-Met uptake, anatomical variations, vascular disorders, non-tumorous lesions such as inflammation or dysplasia, benign brain tumors and patient condition during {sup 11}C-Met PET examination can potentially affect the image interpretation and cause false positives and negatives. These pitfalls in the interpretation of {sup 11}C-Met PET images are important for not only nuclear medicine physicians but also general radiologists. Familiarity with the spectrum and pitfalls of {sup 11}C-Met images could help prevent unfavorable clinical results caused by misdiagnoses.

  13. Fine splits of photon emission spectrum of hydrogen atom caused by transitions between different dressed states in intense high frequency laser field

    Institute of Scientific and Technical Information of China (English)

    Zhou Zhao-Yan; Yuan Jian-Min

    2008-01-01

    The photon emission spectrum of the hydrogen atoms in an intense high-frequency laser pulse is simulated by using one-dimensional soft Coulomb potential. Regular fine structures appear on the two sides of both the odd and even multiples of photon energy of the laser field besides the ordinary odd harmonic peaks. It is proved that the splits of the fine structures are responsible for hyper-Raman lines and the energy spacing between the odd harmonic lines is equal to the difference in energy between the eigenstates with the same parity of the time averaged Krameters-Henneberger (KH) potential. By analysing the features of the fine structures, we also verify that the so-called even order harmonics under the stabilization condition are indeed hyper-Raman lines caused by the transitions between the dressed atomic states with different values of parity.

  14. Atlas and wavenumber tables for visible part ($419 \\div 696$ nm) of the rovibronic multiline emission spectrum of the $D_2$ molecule measured with moderate resolution

    CERN Document Server

    Lavrov, B P

    2012-01-01

    The visible part ($\\approx 419 \\div 696$ nm) of the multiline electronic-vibro-rotational emission spectrum of the $D_2$ molecule was recorded with moderate resolution (line widths $\\approx 0.013$ nm). The resolution was limited by Doppler broadening of spectral lines. After numerical deconvolution of the recorded intensity distributions and proper calibration of the spectrometer the new set of wavenumber values was obtained. The results are reported in the form of an atlas divided into 158 sections (each section covers about 1.5 nm) containing pictures of images in the focal plane of the spectrometer, intensity distributions in linear and logarithmic scales and the table containing wavenumber and relative intensity values for 11990 spectral lines together with existing line assignments.

  15. Planck intermediate results. XXX. The angular power spectrum of polarized dust emission at intermediate and high Galactic latitudes

    Science.gov (United States)

    Planck Collaboration; Adam, R.; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bracco, A.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dolag, K.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Ghosh, T.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Guillet, V.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hivon, E.; Hobson, M.; Holmes, W. A.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jewell, J.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Krachmalnicoff, N.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leahy, J. P.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Remazeilles, M.; Renault, C.; Renzi, A.; Ricciardi, S.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rouillé d'Orfeuil, B.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Soler, J. D.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vibert, L.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Watson, R.; Wehus, I. K.; White, M.; White, S. D. M.; Yvon, D.; Zacchei, A.; Zonca, A.

    2016-02-01

    The polarized thermal emission from diffuse Galactic dust is the main foreground present in measurements of the polarization of the cosmic microwave background (CMB) at frequencies above 100 GHz. In this paper we exploit the uniqueness of the Planck HFI polarization data from 100 to 353 GHz to measure the polarized dust angular power spectra CℓEE and CℓBB over the multipole range 40 <ℓ< 600 well away from the Galactic plane. These measurements will bring new insights into interstellar dust physics and allow a precise determination of the level of contamination for CMB polarization experiments. Despite the non-Gaussian and anisotropic nature of Galactic dust, we show that general statistical properties of the emission can be characterized accurately over large fractions of the sky using angular power spectra. The polarization power spectra of the dust are well described by power laws in multipole, Cℓ ∝ ℓα, with exponents αEE,BB = -2.42 ± 0.02. The amplitudes of the polarization power spectra vary with the average brightness in a way similar to the intensity power spectra. The frequency dependence of the dust polarization spectra is consistent with modified blackbody emission with βd = 1.59 and Td = 19.6 K down to the lowest Planck HFI frequencies. We find a systematic difference between the amplitudes of the Galactic B- and E-modes, CℓBB/CℓEE = 0.5. We verify that these general properties are preserved towards high Galactic latitudes with low dust column densities. We show that even in the faintest dust-emitting regions there are no "clean" windows in the sky where primordial CMB B-mode polarization measurements could be made without subtraction of foreground emission. Finally, we investigate the level of dust polarization in the specific field recently targeted by the BICEP2 experiment. Extrapolation of the Planck 353 GHz data to 150 GHz gives a dust power 𝒟ℓBB ≡ ℓ(ℓ+1)CℓBB/(2π) of 1.32 × 10-2 μKCMB2 over the multipole range

  16. Can the bump in the composite spectrum of GRB 910503 be an emission line feature of gamma-ray bursts?

    Institute of Scientific and Technical Information of China (English)

    Yi-Ping Qin; Fu-Wen Zhang

    2005-01-01

    Appearing in the composite spectral data of BATSE, EGRET and COMPTEL for GRB 910503, there is a bump at around 1600keV. We perform a statistical analysis on the spectral data, trying to find out if the bump could be accounted for by a blue-shifted and significantly broadened rest frame line due to the Doppler effect of an expanding fireball surface. We made an F-test and adopted previously proposed criteria. The study reveals that the criteria are well satisfied and the feature can be interpreted as the blue shifted 6.4 keV line. From the fit with this line taken into account, we find the Lorentz factor of this source to be Γ = 116+9-9 (at the 68% confident level,△X2 = 1) and the rest frame spectral peak energy to be EO,p= 2.96+0.24-0.18 keV. Although the existence of the emission line feature requires other independent tests to confirm, the analysis suggests that it is feasible to detect emission line features in the high energy range of GRB spectra when taking into account the Doppler effect of fireball expansion.

  17. A flat spectrum candidate for a track-type high energy neutrino emission event, the case of blazar PKS 0723-008

    CERN Document Server

    Kun, E; Gergely, L Á

    2016-01-01

    In this Letter we present a model for consecutive emission of low frequency gravitational waves, high energy neutrinos, ultra-high energy cosmic rays, and luminous radio afterglow, all generated by the merger of two supermassive black holes acting as engine. The main contributing events are the spin-flip of the dominant black hole, gravitational wave burst, final coalescence, followed by formation of a new jet, particle acceleration and interaction with the surrounding material (leading to a radio flux density peak and the hardening at radio frequencies). Cross-correlating the Parkes Catalogue and the 2nd Planck Catalogue of Compact Sources with the arrival direction of the track-type neutrino detections by the IceCube, two flat spectrum radio sources emerge as possible origin in the framework of the proposed model. We discuss the blazar PKS 0723-008 as an excellent candidate exhibiting key elements of this complex process, with traces of a spin-flip, high-energy neutrino emission, and five-fold increased rad...

  18. A Relativistic Fe K-alpha Emission Line in the Intermediate Luminosity BeppoSAX Spectrum of the Galactic Microquasar V4641 Sgr

    CERN Document Server

    Miller, J M; in 't Zand, J J M; Reynolds, C S; Wijnands, R; Nowak, M A; Lewin, W H G

    2002-01-01

    Broad Fe K-alpha emission lines have recently been reported in a number of Galactic black holes. Such lines are useful accretion flow diagnostics because they may be produced at the inner accretion disk and shaped by relativistic effects, but in general they have only been observed at luminosities of L_X = 10^(37-38) erg/s in soft X-rays. The Galactic microquasar V4641 Sgr -- widely known for its 12.2 Crab (1.5-12 keV) outburst in 1999 September -- displayed low-level activity in 1999 March. BeppoSAX observed the source in this state and Fe K-alpha line emission was found (in 't Zand et al. 2000). In re-analyzing these data, we find strong evidence that the Fe K-alpha line profile is broadened. For the most likely values of the source distance and black hole mass measured by Orosz et al. (2001), our fits to the total spectrum indicate that the source was observed at a luminosity of L_X = 1.9 (+1.0, -0.8) * 10^(36) erg/s (2-10 keV), or L_(2-10)/L_(Eddington) = 1.8 (+0.9, -0.8) * 10^(-3). Advection-dominated ac...

  19. Timing and Energy Resolution of new near-UV SiPMs coupled to LaBr3:Ce for TOF-PET

    Science.gov (United States)

    Schmall, Jeffrey P.; Wiener, Rony I.; Surti, Suleman; Ferri, Alessandro; Gola, Alberto; Tarolli, Alessandro; Piemonte, Claudio; Karp, Joel S.

    2014-01-01

    The high light output and fast decay time of LaBr3:Ce scintillation detectors leads to excellent timing performance. To realize the potential of timing resolution with LaBr3:Ce we have investigated the performance with SiPMs, which enable 1-to-1 coupling to individual crystals, and which have been optimized for the near-ultraviolet (NUV) scintillation light emission of LaBr3:Ce. Coincidence timing resolution (CTR) of 100 ps was measured for a 4×4×5 mm3 LaBr3:30%Ce crystal directly coupled to a large-area 4×4 mm2 NUV-SiPM. Results show very little dependence on temperature, in the range of −20° to 20°C, and bias voltage, from 2 V to 5 V over breakdown. Optimal performance was achieved at an over-voltage (OV) range of 3 V – 5 V, at which high gain and high photon detection efficiency are achieved. Though saturation was evident at 511 keV, an energy resolution of 6.8% was measured after correcting for non-linearity. We also measured a CTR of 110 ps for a 4×4×5mm3 LaBr3:5%Ce crystal and 245 ps for a 4×4×30 mm3 LaBr3:5%Ce crystal using the NUV-SIPM. The poorer timing measurement for the 30-mm long crystal is due mainly to a systematic shift in the time pick-off as a function of the depth-of-interaction. The excellent temperature stability, fast rise time, high gain, and low noise of the NUV-SiPM make it a practical and highly appealing photodetector for the readout of a LaBr3:Ce TOF-PET detector. PMID:25530626

  20. Forward and Inverse Modeling of the Emission and Transmission Spectrum of GJ 436b: Investigating Metal Enrichment, Tidal Heating, and Clouds

    Science.gov (United States)

    Morley, Caroline V.; Knutson, Heather; Line, Michael; Fortney, Jonathan J.; Thorngren, Daniel; Marley, Mark S.; Teal, Dillon; Lupu, Roxana

    2017-02-01

    The Neptune-mass GJ 436b is one of the most studied transiting exoplanets with repeated measurements of its thermal emission and transmission spectra. We build on previous studies to answer outstanding questions about this planet, including its potentially high metallicity and tidal heating of its interior. We present new observations of GJ 436b’s thermal emission at 3.6 and 4.5 μm, which reduce uncertainties in estimates of GJ 436b’s flux at those wavelengths and demonstrate consistency between Spitzer observations spanning more than 7 yr. We analyze the Spitzer thermal emission photometry and Hubble WFC3 transmission spectrum. We use a dual-pronged modeling approach of both self-consistent and retrieval models. We vary the metallicity, intrinsic luminosity from tidal heating, disequilibrium chemistry, and heat redistribution. We also study clouds and photochemical hazes, but do not find strong evidence for either. The self-consistent and retrieval models combine to suggest that GJ 436b has a high atmospheric metallicity, with best fits at or above several hundred times solar metallicity, tidal heating warming its interior with best-fit intrinsic effective temperatures around 300–350 K, and disequilibrium chemistry. High metal enrichments (>600× solar) occur from the accretion of rocky, rather than icy, material. Assuming the interior temperature Tint ∼ 300–350 K, we find a dissipation factor Q‧ ∼ 2 × 105–106, larger than Neptune’s Q‧, implying a long tidal circularization timescale for the orbit. We suggest that Neptune-mass planets may be more diverse than imagined, with metal enhancements spanning several orders of magnitude, to perhaps over 1000× solar metallicity. High-fidelity observations with instruments like the James Webb Space Telescope will be critical for characterizing this diversity.

  1. Thermal X-Ray Emission from Shocked Ejecta in Type Ia Supernova Remnants II: Parameters Affecting the Spectrum

    CERN Document Server

    Badenes, C; Bravo, E

    2005-01-01

    The supernova remnants left behind by Type Ia supernovae provide an excellent opportunity for the study of these enigmatic objects. In a previous work, we showed that it is possible to use the X-ray spectra of young Type Ia supernova remnants to explore the physics of Type Ia supernovae and identify the relevant mechanism underlying these explosions. Our simulation technique is based on hydrodynamic and nonequilibrium ionization calculations of the interaction of a grid of Type Ia explosion models with the surrounding ambient medium, coupled to an X-ray spectral code. In this work we explore the influence of two key parameters on the shape of the X-ray spectrum of the ejecta: the density of the ambient medium around the supernova progenitor and the efficiency of collisionless electron heating at the reverse shock. We also discuss the performance of recent 3D simulations of Type Ia SN explosions in the context of the X-ray spectra of young SNRs. We find a better agreement with the observations for Type Ia supe...

  2. The Early Spectra of Eta Carinae 1892 to 1941 and the Onset of Its High Excitation Emission Spectrum

    CERN Document Server

    Humphreys, Roberta M; Koppleman, Michael

    2008-01-01

    The observed behavior of eta Car from 1860 to 1940 has not been considered in most recent accounts, nor has it been explained in any quantitative model. We have used modern digital processing techniques to examine Harvard objective-prism spectra made from 1892 to 1941. Relatively high-excitation He I 4471 and [Fe III] 4658 emission, conspicuous today, were weak and perhaps absent throughout those years. Feast et al. noted this qualitative fact for other pre-1920 spectra, but we quantify it and extend it to a time only three years before Gaviola's first observations of the high-excitation features. Evidently the supply of helium-ionizing photons(lambda < 504A) grew rapidly between 1941 and 1944. The apparent scarcity of such far-UV radiation before 1944 is difficult to explain in models that employ a hot massive secondary star,} because no feasible dense wind or obscuration by dust would have hidden the photoionization caused by the proposed companion during most of its orbital period. We also discuss the q...

  3. Comparison study of transparent RF-sputtered ITO/AZO and ITO/ZnO bilayers for near UV-OLED applications

    Science.gov (United States)

    Rezaie, Mahdiyar Nouri; Manavizadeh, Negin; Abadi, Ehsan Mohammadi Nasr; Nadimi, Ebrahim; Boroumand, Farhad Akbari

    2017-01-01

    (EL) spectra, the near band emission (NBE) peak for device with the structure of ITO/ZnO/MEH-PPV/Al is attained nearly in the wavelengths of 408 nm which is in N-UV region. For ITO/AZO/MEH-PPV/Al, a slightly blue shift in NBE peak is observed due to the Burstein-Moss (BM) effect. Ultimately, different charge carrier transport mechanisms of fabricated UV-OLEDs have been carefully investigated.

  4. The WEBT campaign on the BL Lac object PG 1553+113 in 2013. An analysis of the enigmatic synchrotron emission

    CERN Document Server

    Raiteri, C M; Villata, M; Larionov, V M; Acosta-Pulido, J A

    2015-01-01

    A multifrequency campaign on the BL Lac object PG 1553+113 was organized by the Whole Earth Blazar Telescope (WEBT) in 2013 April-August, involving 19 optical, two near-IR, and three radio telescopes. The aim was to study the source behaviour at low energies during and around the high-energy observations by the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes in April-July. We also analyse the UV and X-ray data acquired by the Swift and XMM-Newton satellites in the same period. The WEBT and satellite observations allow us to detail the synchrotron emission bump in the source spectral energy distribution (SED). In the optical we found a general bluer-when-brighter trend. The X-ray spectrum remained stable during 2013, but a comparison with previous observations suggests that it becomes harder when the X-ray flux increases. The long XMM-Newton exposure reveals a curved X-ray spectrum. In the SED, the XMM-Newton data show a hard near-UV spectrum, while Swift data display a softer shape that is co...

  5. New set of experimental wavenumber values for visible part of emission spectrum ($545 \\div 627$ nm) of the $D_2$ molecule with partly resolved fine structure of triplet-triplet rovibronic transitions

    CERN Document Server

    Lavrov, B P

    2011-01-01

    New set of wavenumber values for electronic-vibro-rotational (rovibronic) transitions in limited part of the emission spectrum of the $D_2$ molecule ($545 \\div 627$ nm) have been measured with a precision $0.007 \\div 0.1$ cm$^{-1}$ depending on the translational temperature in plasma, the signal-to-noise ratio, and the degree of overlap with adjacent spectral lines. For the first time partly resolved fine structure of the $D_2$ spectral lines has been observed in the visible part of the spectrum.

  6. The reaction of cardiovascular system and orbital vessels after THz irradiation of molecular spectrum of emission and absorption of 129.0 GHz atmospheric oxygen in healthy volunteers and in patients with involutional macular degeneration

    Directory of Open Access Journals (Sweden)

    Vyacheslav F. Kirichuk

    2013-11-01

    Full Text Available The study aims the influence of THz radiation on 129.0 GHz of atmospheric oxygen on blood pressure (BP and pulse, hemodynamic parameters of orbital arteries during the irradiation of biological active points of application in healthy volunteers and in patients with involutional macular degeneration (IMD. It had been noticed a decrease of systolic and diastolic components of arterial pressure and pulse; a normalization of systolic velocity of bloodstream (SVB and of resistance index (RI in orbital arteries in patients with IMD. The result of the research is: 1 the method of THz influence of on molecular spectrum of emission and absorption of 129.0 GHz atmospheric oxygen is safe and does not cause any negative side effects on common state in healthy volunteers and in patients with IMD; 2 single of THz influence of molecular spectrum of emission and absorption of 129.0 GHz atmospheric oxygen caused a statistical important improvement in vascular system of eyeball.

  7. Retrieval Analysis of the Emission Spectrum of WASP-12b: Sensitivity of Outcomes to Prior Assumptions and Implications for Formation History

    Science.gov (United States)

    Oreshenko, Maria; Lavie, Baptiste; Grimm, Simon L.; Tsai, Shang-Min; Malik, Matej; Demory, Brice-Olivier; Mordasini, Christoph; Alibert, Yann; Benz, Willy; Quanz, Sascha P.; Trotta, Roberto; Heng, Kevin

    2017-09-01

    We analyze the emission spectrum of the hot Jupiter WASP-12b using our HELIOS-R retrieval code and HELIOS-K opacity calculator. When interpreting Hubble and Spitzer data, the retrieval outcomes are found to be prior-dominated. When the prior distributions of the molecular abundances are assumed to be log-uniform, the volume mixing ratio of HCN is found to be implausibly high. A VULCAN chemical kinetics model of WASP-12b suggests that chemical equilibrium is a reasonable assumption even when atmospheric mixing is implausibly rigorous. Guided by (exo)planet formation theory, we set Gaussian priors on the elemental abundances of carbon, oxygen, and nitrogen with the Gaussian peaks being centered on the measured C/H, O/H, and N/H values of the star. By enforcing chemical equilibrium, we find substellar O/H and stellar to slightly superstellar C/H for the dayside atmosphere of WASP-12b. The superstellar carbon-to-oxygen ratio is just above unity, regardless of whether clouds are included in the retrieval analysis, consistent with Madhusudhan et al. Furthermore, whether a temperature inversion exists in the atmosphere depends on one’s assumption for the Gaussian width of the priors. Our retrieved posterior distributions are consistent with the formation of WASP-12b in a solar-composition protoplanetary disk, beyond the water iceline, via gravitational instability or pebble accretion (without core erosion) and migration inward to its present orbital location via a disk-free mechanism, and are inconsistent with both in situ formation and core accretion with disk migration, as predicted by Madhusudhan et al. We predict that the interpretation of James Webb Space Telescope WASP-12b data will not be prior-dominated.

  8. The discovery of a new infrared emission feature at 1905 wavenumbers (5.25 microns) in the spectrum of BD + 30 deg 3639 and its relation to the polycyclic aromatic hydrocarbon model

    Science.gov (United States)

    Allamandola, L. J.; Bregman, J. D.; Sandford, S. A.; Tielens, A. G. G. M.; Witteborn, F. C.

    1989-01-01

    A new IR emission feature at 1905/cm (5.25 microns) has been discovered in the spectrum of BD + 30 deg 3639. This feature joins the family of well-known IR emission features at 3040, 2940, 1750, 1610, '1310', 1160, and 890/cm. The origin of this new feature is discussed and it is assigned to an overtone or combination band involving C-H bending modes of polycyclic aromatic hydrocarbons (PAHs). Laboratory work suggests that spectral studies of the 2000-1650/cm region may be very useful in elucidating the molecular structure of interstellar PAHs. The new feature, in conjunction with other recently discovered spectral structures, suggests that the narrow IR emission features originate in PAH molecules rather than large carbon grains.

  9. Emission color variation of (Ba,Sr)3BP3O12:Eu2+ phosphors for white light LEDs.

    Science.gov (United States)

    Kuo, Te-Wen; Liu, Wei-Ren; Chen, Teng-Ming

    2010-02-01

    A series of alkaline earth borophosphate phosphors, (Ba,Sr)(3)BP(3)O(12) doped with Eu(2+) ions, were synthesized by a solid state reaction. Two emission bands at 465 nm and 520 nm were attributed to the f-d transitions of doped Eu(2+) ions occupying in two different cation sites in host lattices and emission color variation was observed by substituting the M(2+) sites, which was rationalized in terms of two competing factors of the crystal field strength and bond covalence. Green and bluish-white pc-LEDs were fabricated by combination of a 370 nm near-UV chip and composition-optimized Ba(3)BP(3)O(12):Eu(2+) and (Ba,Sr)(3)BP(3)O(12):Eu(2+) phosphors, respectively. The series of phosphors may serve as a promising green and bluish-white luminescent materials used in fabrication of near UV-based white pc-LEDs.

  10. The Complete Ultraviolet Spectrum of the Archetypal "Wind-dominated" Quasar Mrk 231: Absorption and Emission from a High-speed Dusty Nuclear Outflow

    Science.gov (United States)

    Veilleux, S.; Meléndez, M.; Tripp, T. M.; Hamann, F.; Rupke, D. S. N.

    2016-07-01

    New near- and far-ultraviolet (NUV and FUV) Hubble Space Telescope spectra of Mrk 231, the nearest quasar known, are combined with ground-based optical spectra to study the remarkable dichotomy between the FUV and NUV-optical spectral regions in this object. The FUV emission-line features are faint, broad, and highly blueshifted (up to ˜7000 km s-1), with no significant accompanying absorption. In contrast, the profiles of the NUV absorption features resemble those of the optical Na i D, He i, and Ca ii H and K lines, exhibiting broad blueshifted troughs that overlap in velocity space with the FUV emission-line features and indicate a dusty, high-density and patchy broad absorption line (BAL) screen covering ˜90% of the observed continuum source at a distance ≲2-20 pc. The FUV continuum emission does not show the presence of any obvious stellar features and is remarkably flat compared with the steeply declining NUV continuum. The NUV (FUV) features and continuum emission have not varied significantly over the past ˜22 (3) years and are unresolved on scales ˜40 (170) pc. These results favor an active galactic nucleus origin for the NUV-FUV line and continuum emission. The observed FUV line emission is produced in the outflowing BAL cloud system, while the Balmer lines arise primarily from the standard broad line region seen through the dusty BAL screen. Our data are inconsistent with the recently proposed binary black hole model. We argue instead that Mrk 231 is the nearest example of weak-lined “wind-dominated” quasars with high Eddington ratios and geometrically thick (“slim”) accretion disks; these quasars are likely more common in the early universe.

  11. The Complete Ultraviolet Spectrum of the Archetypal "Wind-Dominated" Quasar Mrk~231: Absorption and Emission from a High-Speed Dusty Nuclear Outflow

    CERN Document Server

    Veilleux, S; Tripp, T M; Hamann, F; Rupke, D S N

    2016-01-01

    New near- and far-ultraviolet (NUV and FUV) HST spectra of Mrk 231, the nearest quasar known, are combined with ground-based optical spectra to study the remarkable dichotomy between the FUV and NUV-optical spectral regions in this object. The FUV emission-line features are faint, broad, and highly blueshifted (up to ~7000 km/s), with no significant accompanying absorption. In contrast, the profiles of the NUV absorption features resemble those of the optical Na I D, He I, and Ca II H and K lines, exhibiting broad blue-shifted troughs that overlap in velocity space with the FUV emission-line features and indicate a dusty, high-density and patchy broad absorption line (BAL) screen covering ~90% of the observed continuum source at a distance less than ~2 - 20 pc. The FUV continuum emission does not show the presence of any obvious stellar features and is remarkably flat compared with the steeply declining NUV continuum. The NUV (FUV) features and continuum emission have not varied significantly over the past ~2...

  12. The discovery of a new infrared emission feature at 1905 wavenumbers (5.25 microns) in the spectrum of BD +30 degrees 3639 and its relation to the polycyclic aromatic hydrocarbon model

    Science.gov (United States)

    Allamandola, L. J.; Bregman, J. D.; Sandford, S. A.; Tielens, A. G.; Witteborn, F. C.; Wooden, D. H.; Rank, D.

    1989-01-01

    We have discovered a new IR emission feature at 1905 cm-1 (5.25 microns) in the spectrum of BD +30 degrees 3639. This feature joins the family of well-known IR emission features at 3040, 2940, 1750, 1610, "1310," 1160, and 890 cm-1 (3.3, 3.4, 5.7, 6.2, "7.7," 8.6, and 11.2 microns). The origin of this new feature is discussed and it is assigned to an overtone or combination band involving C-H bending modes of polycyclic aromatic hydrocarbons (PAHs). Laboratory work suggests that spectral studies of the 2000-1650 cm-1 (5.0-6.1 microns) region may be very useful in elucidating the molecular structure of interstellar PAHs. The new feature, in conjunction with other recently discovered spectral structure, suggests that the narrow IR emission features originate in PAH molecules rather than large carbon grains. Larger species are likely to be the source of the broad underlying "plateaus" seen in many of the spectra.

  13. Specific solvent effects of linear alcohols on the emission spectrum and the excited state decay of tris(2,2'-bipyridyl) ruthenium(I)

    Science.gov (United States)

    Hartmann, Paul; Leiner, Marc J. P.; Draxler, Sonja; Lippitsch, Max E.

    1996-06-01

    This study aims at a quantitative extraction of specific solvent effects of hydroxylic solvents on the non-radiative decay of tris(2,2'-bipyridyl) ruthenium(II). For this purpose the emission spectra, quantum yields and excited state lifetimes of the dye were measured in a series of monovalent linear alcohols. Separation of the non-radiative decay via the energy gap was achieved by evaluating the temperature dependence of quantum yields to account for temperature-activated transitions. The parameters determining the shapes of the emission spectra were calculated by a modified Franck-Condon analysis including the anharmonic Morse potential, and correlated with the non-radiative rate with the help of the energy gap law. The specific effects of hydroxylic solvents were finally obtained by comparison with the well-known behavior in non-hydroxylic solvents, and interpreted with the help of the energy gap law theory.

  14. Fermi-LAT Detection of a Hard Spectrum and Enhanced Gamma-ray Emission from the Blazar PMN J2052-5533

    Science.gov (United States)

    Carpenter, Bryce; Magill, Jeff; Ojha, Roopesh

    2015-09-01

    The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed an unusually hard spectrum gamma-ray flare from a source positionally consistent with the blazar PMN J2052-5533 (3FGL J2051.8-5535; Acero et al. 2015, ApJS 218, 23), with coordinates RA: 20h52m13.68s, Dec: -55d33m10.0s, J2000, (Healey et al. 2007, ApJS, 171, 61). There is no redshift reported for this source in the literature.

  15. Realization of color hue tuning via efficient Tb3+-Mn2+ energy transfer in Sr3Tb(PO4)3:Mn2+, a potential near-UV excited phosphor for white LEDs.

    Science.gov (United States)

    Jia, Yongchao; Lü, Wei; Guo, Ning; Lü, Wenzhen; Zhao, Qi; You, Hongpeng

    2013-04-28

    A n-UV convertible phosphor Sr3Tb(PO4)3:Mn(2+) with tunable-emitting color has been synthesized by solid state reaction. The GSAS refinement shows that the obtained powder crystallizes as a cubic unit cell with space group I43d, and Mn(2+) ions occupy the Sr(2+) crystallographic sites. Under (7)F6→(5)D3 of Tb(3+) excitation at 381 nm, Sr3Tb(PO4)3:Mn(2+) not only exhibits (5)D4→(7)F6-3 of Tb(3+) green emission lines but also (4)T1→(6)A1 of the Mn(2+) orange emission band. In addition, the intensity ratio of the orange/green emission bands can be enhanced through the increase of Mn(2+) content. The intense orange emission band of the Mn(2+) ions is attributed to the efficient energy transfer from the Tb(3+) to Mn(2+) ions, which has been justified through the luminescence spectra and fluorescence decay dynamics. The energy transfer mechanism was demonstrated to be the electric dipole-dipole interaction based on the Inokuti-Hirayama theoretical model, and the energy transfer efficiency was calculated. Optimal-composition samples show high external quantum efficiency, up to 59.3%, indicating the potential of the powder as a n-UV convertible phosphor for white LEDs.

  16. The angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its Dark Matter interpretation

    CERN Document Server

    Fornasa, Mattia; Zavala, Jesus; Gaskins, Jennifer M; Sanchez-Conde, Miguel A; Gomez-Vargas, German; Komatsu, Eiichiro; Linden, Tim; Prada, Francisco; Zandanel, Fabio; Morselli, Aldo

    2016-01-01

    The isotropic gamma-ray background arises from the contribution of unresolved sources, including members of confirmed source classes and proposed gamma-ray emitters such as the radiation induced by dark matter annihilation and decay. Clues about the properties of the contributing sources are imprinted in the anisotropy characteristics of the gamma-ray background. We use 81 months of Pass 7 Reprocessed data from the Fermi Large Area Telescope to perform a measurement of the anisotropy angular power spectrum of the gamma-ray background. We analyze energies between 0.5 and 500 GeV, extending the range considered in the previous measurement based on 22 months of data. We also compute, for the first time, the cross-correlation angular power spectrum between different energy bins. We find that the derived angular spectra are compatible with being Poissonian, i.e. constant in multipole. Moreover, the energy dependence of the anisotropy suggests that the signal is due to two populations of sources, contributing, resp...

  17. Fermi-LAT Detection of an Unusual Hard Spectrum and Enhanced Gamma-ray Emission from the FSRQ PKS B1035-281

    Science.gov (United States)

    Carpenter, Bryce; Ojha, Roopesh

    2016-02-01

    The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed increasing gamma-ray flux and an unusually hard spectrum from a source positionally consistent with the flat spectrum radio quasar PKS B1035-281 (also known as 3FGL J1037.5-2821, Acero et al. 2015, ApJS, 218, 23) with radio coordinates R.A.: 159.4269058 deg, Dec: -28.3844750 deg (J2000, Beasley et al. 2002, ApJS, 141, 13) at redshift z=1.066 (Shaw et al. 2012, ApJ, 748, 49). Preliminary analysis indicates that on 24 February 2016 this source was in a high-flux state, with a daily averaged gamma-ray flux (E > 100MeV) of (0.7+/-0.1) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only) corresponding to a flux increase of a factor of about 30 over its four-year average flux (3FGL J1037.5-2821).

  18. Atlas and wavenumber tables for visible part of the rovibronic multiline emission spectrum of the $D_2$ molecule. I. Wavenumber range $23894 \\div 18161$ cm$^{-1}$ measured with moderate resolution

    CERN Document Server

    Lavrov, B P

    2012-01-01

    The visible part ($\\approx 419 \\div 550$ nm) of the multiline electronic-vibro-rotational emission spectrum of the $D_2$ molecule was recorded with moderate resolution (line widths $\\approx 0.013$ nm). The resolution was limited by Doppler broadening of spectral lines. After numerical deconvolution of the recorded intensity distributions and proper calibration of the spectrometer the new set of wavenumber values was obtained. The results are reported in the form of an atlas divided into 36 sections covering about 1.5 nm, containing pictures of images in the focal plane of the spectrometer, intensity distributions in linear and logarithmic scales and the table containing wavenumber and relative intensity values for 6545 spectral lines together with existing line assignments.

  19. Atlas and wavenumber tables for visible part of the rovibronic multiline emission spectrum of the $D_2$ molecule. II. Wavenumber range $18161 \\div 14379$ cm$^{-1}$ measured with moderate resolution

    CERN Document Server

    Lavrov, B P

    2012-01-01

    The visible part ($\\approx 550 \\div 696$ nm) of the multiline electronic-vibro-rotational emission spectrum of the $D_2$ molecule was recorded with moderate resolution (line widths $\\approx 0.013$ nm). The resolution was limited by Doppler broadening of spectral lines. After numerical deconvolution of the recorded intensity distributions and proper calibration of the spectrometer the new set of wavenumber values was obtained. The results are reported in the form of an atlas divided into 43 sections covering about 1.5 nm, containing pictures of images in the focal plane of the spectrometer, intensity distributions in linear and logarithmic scales and the table containing wavenumber and relative intensity values for 5445 spectral lines together with existing line assignments.

  20. Neutron activation of natural materials in a PWR spectrum: feedback on {sup 116m}In relative γ emission intensities and half-life

    Energy Technology Data Exchange (ETDEWEB)

    Gruel, Adrien; Geslot, Benoit; Di Salvo, Jacques; Blaise, Patrick; Girard, Jean-Michel; Destouches, Christophe [CEA, DEN, SPEx, Cadarache, F-13108 St Paul lez Durance (France)

    2015-07-01

    During the MAESTRO program, carried out between 2011 and 2014 in MINERVE zero power reactor, common Gen-II and Gen-III light water reactor materials were irradiated. For some of these materials, the decay of their activation products was also measured by γ spectrometry. Initially devoted to the measurement of the integral capture cross section by activation and reactivity-oscillation method, these results can also provide useful information on decay data of various radionuclides. This approach of this experiment led to a common roadmap shared by the Experimental Physics Section and the Henri Becquerel National Laboratory to improve decay data in nuclear data libraries. Results discussed in this paper concern the relative emission intensities of the main γ rays of {sup 116m}In. Six irradiations of samples with various physical forms of {sup nat}In were carried out. Measurements were analyzed using decay data from several evaluations and it is shown that γ ray activities are not consistent. Analyses were carried out to provide new relative γ emission intensities from these measurements. The {sup 116m}In half-life has also been measured and shows a good agreement with existing values. Finally, an overview of the foreseen results on additional decay data from the MAESTRO program is given. (authors)

  1. [Study on the method for the determination of trace boron, molybdenum, silver, tin and lead in geochemical samples by direct current arc full spectrum direct reading atomic emission spectroscopy (DC-Arc-AES)].

    Science.gov (United States)

    Hao, Zhi-hong; Yao, Jian-zhen; Tang, Rui-ling; Zhang, Xue-mei; Li, Wen-ge; Zhang, Qin

    2015-02-01

    The method for the determmation of trace boron, molybdenum, silver, tin and lead in geochemical samples by direct current are full spectrum direct reading atomic emission spectroscopy (DC-Arc-AES) was established. Direct current are full spectrum direct reading atomic emission spectrometer with a large area of solid-state detectors has functions of full spectrum direct reading and real-time background correction. The new electrodes and new buffer recipe were proposed in this paper, and have applied for national patent. Suitable analytical line pairs, back ground correcting points of elements and the internal standard method were selected, and Ge was used as internal standard. Multistage currents were selected in the research on current program, and each current set different holding time to ensure that each element has a good signal to noise ratio. Continuous rising current mode selected can effectively eliminate the splash of the sample. Argon as shielding gas can eliminate CN band generating and reduce spectral background, also plays a role in stabilizing the are, and argon flow 3.5 L x min(-1) was selected. Evaporation curve of each element was made, and it was concluded that the evaporation behavior of each element is consistent, and combined with the effects of different spectrographic times on the intensity and background, the spectrographic time of 35s was selected. In this paper, national standards substances were selected as a standard series, and the standard series includes different nature and different content of standard substances which meet the determination of trace boron, molybdenum, silver, tin and lead in geochemical samples. In the optimum experimental conditions, the detection limits for B, Mo, Ag, Sn and Pb are 1.1, 0.09, 0.01, 0.41, and 0.56 microg x g(-1) respectively, and the precisions (RSD, n=12) for B, Mo, Ag, Sn and Pb are 4.57%-7.63%, 5.14%-7.75%, 5.48%-12.30%, 3.97%-10.46%, and 4.26%-9.21% respectively. The analytical accuracy was

  2. Experimental studies on the neutron emission spectrum and activation cross-section for 40 MeV deuterons in IFMIF accelerator structural elements

    Energy Technology Data Exchange (ETDEWEB)

    Hagiwara, M. E-mail: hagi@cyric.tohoku.ac.jp; Itoga, T.; Baba, M.; Uddin, M.S.; Hirabayashi, N.; Oishi, T.; Yamauchi, T

    2004-08-01

    In order to improve the nuclear data required in the safety design of the International Fusion Materials Irradiation Facility (IFMIF), we have measured the neutron emission spectra and the activation cross-sections of the IFMIF accelerator structural elements, C and Al, for 40 MeV deuterons using the Tohoku University AVF cyclotron. Neutron spectra from thick C and Al targets were measured with the time-of-flight method at ten laboratory angles between 0- and 110-deg. using a beam swinger system and a well collimated neutron flight channel. The data were obtained over almost entire energy range of secondary neutrons using a two-detector method. Activation cross-sections were measured by detecting the {gamma}-rays from C and Al targets with a high-pure Ge detector. The stacked target technique was used to obtain the data from 40 MeV down to the threshold energy.

  3. On the use of laser induced breakdown spectroscopy to characterize the naturally existing crystal in Pakistan and its optical emission spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Javed; Mahmood, S.; Tufail, Iram; Asghar, H.; Ahmed, R.; Baig, M.A., E-mail: baig@qau.edu.pk

    2015-09-01

    We have used the Laser Induced Breakdown Spectroscopic (LIBS) technique to qualitatively identify the naturally existing transparent crystal as a pure quartz (SiO{sub 2}) by observing its optical emission spectra using a Q-switched Nd:YAG laser, fundamental wavelength at 1064 nm and second harmonic at 532 nm. The spectra were registered using a set of five miniature spectrometers covering the spectral range from 200 nm to 720 nm. The plasma temperature has been calculated in the range from 8500 K to 10,200 K and the electron densities determined from the Stark broadened spectral lines in the range of 1.0 × 10{sup 17} cm{sup −3} to 6.0 × 10{sup 17} cm{sup −3}. We report here the full widths at maximum of the spectral lines associated with the 3p4s {sup 3}P{sub 0,1,2} → 3p{sup 23}P{sub 0,1,2}, {sup 1}S{sub 0}, {sup 1}D{sub 2} transitions in Si and four multiplets of singly ionized silicon. - Highlights: • Characterization of naturally existing transparent crystal as pure quartz (SiO{sub 2}) using LIBS. • Determination of plasma parameters and full width at half maximum of the neutral and singly ionized silicon lines. • Confirmation of optically thin plasma validity of LTE.

  4. Measurement of the 1s2l3l’ Dielectronic Recombination Emission Line in Li-Like Ar and Its Contribution to the Faint X-Ray Feature Found in the Stacked Spectrum of Galaxy Clusters

    Science.gov (United States)

    Gall, Amy Christina; Silwal, Roshani; Dreiling, Joan; Borovik, Alexander; Ajello, Marco; Gillaspy, John; Kilgore, Ethan; Ralchenko, Yuri; Takacs, Endre

    2016-06-01

    Driven by the recent detection of an unidentified emission line previously reported at 3.55-3.57 keV in a stacked spectrum of galaxy clusters, we investigated the resonant DR process in Li-like Ar as a possible source of, or contributor to, the emission line. The Li-like transition 1s22l-1s2l3l’ was suggested to produce a 3.62 keV photon [1] near the unidentified line at 3.57 keV and was the primary focus of our investigation. Apart from the mentioned transitions, we have found other features that can be possible contributors to the emission in this region. The Electron Beam Ion Trap at NIST was used to produce and trap the highly-charged ions of argon. The energy of the quasi-monoenergetic electron beam was incremented in steps of 15 eV to scan over all of the Li-like Ar DR resonances. A Johann-type crystal spectrometer and a solid-state germanium detector were used to take x-ray measurements perpendicular to the electron beam. The DR cross sections were measured and normalized to the well-known photoionization cross sections using radiative recombination peaks in the measured spectra. Corrections for different instrument and method related effects such as charge state balance, electron beam space charge, and charge exchange have been considered. Our high-resolution crystal spectra allowed the experimental separation of features that are less than 2 eV apart. We have used a collisional radiative model NOMAD [2] aided by atomic data calculations by FAC [3] to interpret our observations and account for the corrections and uncertainties. Experimental results were compared to the AtomDB theoretical emission lines used to fit the galaxy cluster spectra containing the unidentified 3.57 keV line. These data points can be added benchmarks in the database and used to accurately interpret spectra from current x-ray satellites, including Hitomi, Chandra, and XMM-Newton x-ray observatories.[1] Bulbul E. et al., 2014, ApJ, 789, 13[2] Ralchenko Yu. et al., 2014, JQSRT, 71

  5. Blue-emitting K2Al2B2O7:Eu(2+) phosphor with high thermal stability and high color purity for near-UV-pumped white light-emitting diodes.

    Science.gov (United States)

    Xiao, Wenge; Zhang, Xia; Hao, Zhendong; Pan, Guo-Hui; Luo, Yongshi; Zhang, Ligong; Zhang, Jiahua

    2015-04-06

    Novel blue-emitting K2Al2B2O7:Eu(2+) (KAB:Eu(2+)) phosphor was synthesized by solid state reaction. The crystal structural and photoluminescence (PL) properties of KAB:Eu(2+) phosphor, as well as its thermal properties of the photoluminescence, were investigated. The KAB:Eu(2+) phosphor exhibits broad excitation spectra ranging from 230 to 420 nm, and an intense asymmetric blue emission band centered at 450 nm under λex = 325 nm. Two different Eu(2+) emission centers in KAB:Eu(2+) phosphor were confirmed via their fluorescence decay lifetimes. The optimal concentration of Eu(2+) ions in K2-xEuxAl2B2O7 was determined to be x = 0.04 (2 mol %), and the corresponding concentration quenching mechanism was verified to be the electric dipole-dipole interactions. The PL intensity of the nonoptimized KAB:0.04Eu(2+) phosphor was measured to be ∼58% that of the commercial blue-emitting BaMgAl10O17:Eu(2+) phosphor, and this phosphor has high color purity with the CIE coordinate (0.147, 0.051). When heated up to 150 °C, the KAB:0.04Eu(2+) phosphor still has 82% of the initial PL intensity at room temperature, indicating its high thermal stability. These results suggest that the KAB:Eu(2+) is a promising candidate as a blue-emitting n-UV convertible phosphor for application in white light emitting diodes.

  6. Global Analysis of the High Temperature Infrared Emission Spectrum of 12CH_4 in the Dyad (ν_2/ν_4) Region

    Science.gov (United States)

    Amyay, Badr; Louviot, Maud; Pirali, Olivier; Georges, Robert; Vander Auwera, Jean; Boudon, Vincent

    2016-06-01

    We report new assignments of vibration-rotation line positions of methane (12CH_4) in the so-called Dyad (ν_2/ν_4) region (1000 -- 1500 cm-1), and the resulting update of the vibration-rotation effective model of methane, previously reported by Nikitin et al. [A.V. Nikitin et al. PCCP, 15, (2013), 10071], up to and including the Tetradecad. High resolution (0.01 cm-1) emission spectra of methane have been recorded up to about 1400 K using the high-enthalpy source developed at IPR associated with the Fourier transform spectrometer of the SOLEIL synchrotron facility (AILES beamline). Analysis of these spectra allowed extending rotational assignments in the well-known cold band (Dyad-GS) and related hot bands in the Pentad-Dyad system (3000 cm-1) up to Jmax=30 and 29, respectively. In addition, 8512 new transitions belonging to the Octad-Pentad (up to J=28) and Tetradecad-Octad (up to J=21) hot band systems were successfully identified. As a result, the MeCaSDa database of methane was significantly improved. The line positions assigned in this work, together with the information available in the literature, were fitted using 1096 effective parameters with a dimensionless standard deviation σ = 2.09. The root mean square deviations dRMS are 3.60 × 10-3 cm-1 for Dyad-GS cold band, 4.47 × 10-3 cm-1 for the Pentad-Dyad, 5.43 × 10-3 cm-1 for the Octad-Pentad and 4.70 × 10-3 cm-1 for the Tetradecad-Octad hot bands. The resulting new line list will contribute to improve opacity and radiative transfer models for hot atmospheres, such as those of hot-Jupiter type exoplanets.

  7. On the Location of the gamma-Ray Outburst Emission in the BL Lacertae Object AO 0235 + 164 Through Observations Across the Electromagnetic Spectrum

    Science.gov (United States)

    Agudo, Ivan; Marscher, Alan P.; Jorstad, Svetlana G.; Larionov, Valeri M.; Gomez, Jose L.; Laehteenmaeki, Anne; Smith, Paul S.; Nilsson, Kari; Readhead, Anthony C. S.; Aller, Margo F.; Heidt, Jochien; Gurwell, Mark; Thum, Clemens; Wehrle, Ann E.; Nikolashvili, Maria G.; Aller, Hugh D.; Benitez, Erika; Blinov, Dmitriy A.; Hagen-Thorn, Vladimir A.; Hiriart, David; Jannuzi, Buell T.; Joshi, Manasvita; Kimeridze, Givi N.; Kurtanidze, Omar M.; Kurtanidze, Sofia O.

    2011-01-01

    We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and gamma-ray wavelengths of the BL Lacertae object AO 0235+164. We analyze the timing of multi-waveband variations in the flux and linear polarization, as well as changes in Very Long Baseline Array images at A = 7 mm with approx.0.15 milliarcsec resolution. The association of the events at different wavebands is confirmed at high statistical significance by probability arguments and Monte Carlo simulations. A series of sharp peaks in optical linear polarization, as well as a pronounced maximum in the 7 mm polarization of a superluminal jet knot, indicate rapid fluctuations in the degree of ordering of the magnetic field. These results lead us to conclude that the outburst occurred in the jet both in the quasi-stationary "core" and in the superluminal knot, both parsecs downstream of the supermassive black hole. We interpret the outburst as a consequence of the propagation of a disturbance, elongated along the line of sight by light-travel time delays, that passes through a standing recollimation shock in the core and propagates down the jet to create the superluminal knot. The multi-wavelength light curves vary together on long timescales (months/ years), but the correspondence is poorer on shorter timescales. This, as well as the variability of the polarization and the dual location of the outburst, agrees with the expectations of a multi-zone emission model in which turbulence plays a major role in modulating the synchrotron and inverse Compton fluxes.

  8. On the Location of the gamma-Ray Outburst Emission in the BL Lacertae Object AO 0235 + 164 Through Observations Across the Electromagnetic Spectrum

    Science.gov (United States)

    Agudo, Ivan; Marscher, Alan P.; Jorstad, Svetlana G.; Larionov, Valeri M.; Gomez, Jose L.; Laehteenmaeki, Anne; Smith, Paul S.; Nilsson, Kari; Readhead, Anthony C. S.; Aller, Margo F.; hide

    2011-01-01

    We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and gamma-ray wavelengths of the BL Lacertae object AO 0235+164. We analyze the timing of multi-waveband variations in the flux and linear polarization, as well as changes in Very Long Baseline Array images at A = 7 mm with approx.0.15 milliarcsec resolution. The association of the events at different wavebands is confirmed at high statistical significance by probability arguments and Monte Carlo simulations. A series of sharp peaks in optical linear polarization, as well as a pronounced maximum in the 7 mm polarization of a superluminal jet knot, indicate rapid fluctuations in the degree of ordering of the magnetic field. These results lead us to conclude that the outburst occurred in the jet both in the quasi-stationary "core" and in the superluminal knot, both parsecs downstream of the supermassive black hole. We interpret the outburst as a consequence of the propagation of a disturbance, elongated along the line of sight by light-travel time delays, that passes through a standing recollimation shock in the core and propagates down the jet to create the superluminal knot. The multi-wavelength light curves vary together on long timescales (months/ years), but the correspondence is poorer on shorter timescales. This, as well as the variability of the polarization and the dual location of the outburst, agrees with the expectations of a multi-zone emission model in which turbulence plays a major role in modulating the synchrotron and inverse Compton fluxes.

  9. Global analysis of the high temperature infrared emission spectrum of {sup 12}CH{sub 4} in the dyad (ν{sub 2}/ν{sub 4}) region

    Energy Technology Data Exchange (ETDEWEB)

    Amyay, Badr, E-mail: badr.amyay@gmail.com, E-mail: vincent.boudon@u-bourgogne.fr; Louviot, Maud; Boudon, Vincent, E-mail: badr.amyay@gmail.com, E-mail: vincent.boudon@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS, Université Bourgogne Franche-Comté, 9 Avenue A. Savary, BP 47870, 21078 Dijon Cedex (France); Pirali, Olivier [Ligne AILES, Synchrotron SOLEIL, L’Orme des Merisiers, F-91192 Gif-sur-Yvette, France and Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS, Université Paris Sud, Université Paris-Saclay, F-91405 Orsay (France); Georges, Robert [Institut de Physique de Rennes, UMR 6251, Campus de Beaulieu, Université de Rennes 1/CNRS, F-35042 Rennes Cedex (France); Vander Auwera, Jean [Service de Chimie Quantique et Photophysique, C.P. 160/09, Université Libre de Bruxelles, 50 Avenue F. D. Roosevelt, B-1050 Brussels (Belgium)

    2016-01-14

    We report new assignments of vibration-rotation line positions of methane ({sup 12}CH{sub 4}) in the so-called dyad (ν{sub 2}/ν{sub 4}) region (1100–1500 cm{sup −1}), and the resulting update of the vibration-rotation effective model of methane, previously reported by Nikitin et al. [Phys. Chem. Chem. Phys. 15, 10071 (2013)], up to and including the tetradecad. High resolution (0.01 cm{sup −1}) emission spectra of methane have been recorded up to about 1400 K using the high-enthalpy source developed at Institut de Physique de Rennes associated with the Fourier transform spectrometer of the SOLEIL synchrotron facility (AILES beamline). Analysis of these spectra allowed extending rotational assignments in the well-known cold band (dyad-ground state (GS)) and related hot bands in the pentad–dyad system (3000 cm{sup −1}) up to J{sub max} = 30 and 29, respectively. In addition, 8512 new transitions belonging to the octad–pentad (up to J = 28) and tetradecad-octad (up to J = 21) hot band systems were successfully identified. As a result, the MeCaSDa database of methane was significantly improved. The line positions assigned in this work, together with the information available in the literature, were fitted using 1096 effective parameters with a dimensionless standard deviation σ = 2.09. The root mean square deviations d{sub RMS} are 3.60 × 10{sup −3} cm{sup −1} for dyad-GS cold band, 4.47 ×10{sup −3} cm{sup −1} for the pentad–dyad, 5.43 × 10{sup −3} cm{sup −1} for the octad–pentad, and 4.70 × 10{sup −3} cm{sup −1} for the tetradecad–octad hot bands. The resulting new line list will contribute to improve opacity and radiative transfer models for hot atmospheres, such as those of hot-Jupiter type exoplanets.

  10. New yellow-emitting Whitlockite-type structure Sr(1.75)Ca(1.25)(PO4)2:Eu(2+) phosphor for near-UV pumped white light-emitting devices.

    Science.gov (United States)

    Ji, Haipeng; Huang, Zhaohui; Xia, Zhiguo; Molokeev, Maxim S; Atuchin, Victor V; Fang, Minghao; Huang, Saifang

    2014-05-19

    New compound discovery is of interest in the field of inorganic solid-state chemistry. In this work, a whitlockite-type structure Sr1.75Ca1.25(PO4)2 newly found by composition design in the Sr3(PO4)2-Ca3(PO4)2 join was reported. Crystal structure and luminescence properties of Sr1.75Ca1.25(PO4)2:Eu(2+) were investigated, and the yellow-emitting phosphor was further employed in fabricating near-ultraviolet-pumped white light-emitting diodes (w-LEDs). The structure and crystallographic site occupancy of Eu(2+) in the host were identified via X-ray powder diffraction refinement using Rietveld method. The Sr1.75Ca1.25(PO4)2:Eu(2+) phosphors absorb in the UV-vis spectral region of 250-430 nm and exhibit an intense asymmetric broadband emission peaking at 518 nm under λex = 365 nm which is ascribed to the 5d-4f allowed transition of Eu(2+). The luminescence properties and mechanism are also investigated as a function of Eu(2+) concentration. A white LED device which is obtained by combining a 370 nm UV chip with commercial blue phosphor and the present yellow phosphor has been fabricated and exhibit good application properties.

  11. Zellweger Spectrum

    Science.gov (United States)

    ... severe defect, resulting in essentially nonfunctional peroxisomes. This phenomenon produces the range of severity of the disorders. How is the Zellweger Spectrum Diagnosed? The distinctive shape of the head and face of a child born with one of the diseases of the ...

  12. Gd{sub 3}B(W,Mo)O{sub 9}: Eu{sup 3+} red phosphor: From structure design to photoluminescence behavior and near-UV white-LEDs performance

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Shuangli [State Key Lab of Luminescent Materials and Devices, and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510641 (China); Ye, Shi, E-mail: msyes@scut.edu.cn [State Key Lab of Luminescent Materials and Devices, and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510641 (China); Wang, Lingli [Institute of Rare Metals, Guangzhou Research Institute of Non-Ferrous Metals, Guangzhou 510650 (China); Chen, Xingyuan; Yang, Shaobei; Zhao, Yujun [State Key Lab of Luminescent Materials and Devices, and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510641 (China); Wang, Jiaguo; Jing, Xiping [Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Zhang, Qinyuan, E-mail: qyzhang@scut.edu.cn [State Key Lab of Luminescent Materials and Devices, and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510641 (China)

    2014-10-15

    Highlights: • Red phosphor Gd{sub 3}B(W,Mo)O{sub 9}:Eu{sup 3+} designed according to structure was synthesized. • The substitution of W{sup 6+} by Mo{sup 6+} makes the absorption band edge of this phosphor extend to 440 nm. • The energy transfer from MoO{sub 6} to Eu{sup 3+} improves the temperature quenching property of photoluminescence in this system. • Red emission of the optimized phosphor is almost 10 times stronger than that of Y{sub 2}O{sub 2}S:Eu{sup 3+}. • The performance of NUV w-LEDs device fabricated with this phosphor verified the potential application. - Abstract: The photoluminescence behavior of a high efficient red phosphor Gd{sub 3}B(W,Mo)O{sub 9}:Eu{sup 3+} designed according to crystal structure and electronic structure is presented in detail. The substitution of isolated WO{sub 6} group by MoO{sub 6} makes the absorption band edge extend from 360 nm to 440 nm, as designed to fit the excitation of near ultraviolet (NUV) LED chip, which could be interpreted by the density functional theory calculations. The extreme low symmetry (C{sub 1}) of Eu{sup 3+}(Gd{sup 3+}) site enables Eu{sup 3+} ion to show dominant electronic dipole transition {sup 5}D{sub 0} → {sup 7}F{sub 2} (∼616 nm) with five apparent splitting peaks according to group theory, which is almost 10 times stronger than that of commercial Y{sub 2}O{sub 2}S:Eu{sup 3+} upon ∼385 nm excitation. The outstanding thermal stability of photoluminescence of this phosphor up to 523 K may probably be owed to the energy transfer from isolated MoO{sub 6} groups to the well-dispersed Eu{sup 3+} ion separated by BO{sub 3} groups. The performance of NUV white-LEDs package fabricated with a blue, green and this red phosphor is also demonstrated. It shows high color stability of the white light (CIE coordinate (0.320, 0.349), CCT 6031K, at 20 mA) under the DC drive current varied from 20 mA to 350 mA, verifying the potential application of the red phosphor in tri-color phosphors coated

  13. Phenomenology of magnetospheric radio emissions

    Science.gov (United States)

    Carr, T. D.; Desch, M. D.; Alexander, J. K.

    1983-01-01

    Jupiter has now been observed over 24 octaves of the radio spectrum, from about 0.01 MHz to 300,000 MHz. Its radio emissions fill the entire spectral region where interplanetary electromagnetic propagation is possible at wavelengths longer than infrared. Three distinct types of radiation are responsible for this radio spectrum. Thermal emission from the atmosphere accounts for virtually all the radiation at the high frequency end. Synchrotron emission from the trapped high-energy particle belt deep within the inner magnetosphere is the dominant spectral component from about 4000 to 40 MHz. The third class of radiation consists of several distinct components of sporadic low frequency emission below 40 MHz. The decimeter wavelength emission is considered, taking into account the discovery of synchrotron emission, radiation by high-energy electrons in a magnetic field, and the present status of Jovian synchrotron phenomenology. Attention is also given to the decameter and hectometer wavelength emission, and emissions at kilometric wavelengths.

  14. Luminescence properties and energy transfer of site-sensitive Ca(6-x-y)Mg(x-z)(PO(4))(4):Eu(y)(2+),Mn(z)(2+) phosphors and their application to near-UV LED-based white LEDs.

    Science.gov (United States)

    Kwon, Ki Hyuk; Im, Won Bin; Jang, Ho Seong; Yoo, Hyoung Sun; Jeon, Duk Young

    2009-12-21

    On the basis of the structural information that the host material has excellent charge stabilization, blue-emitting Ca(6-x-y)Mg(x)(PO(4))(4):Eu(y)(2+) (CMP:Eu(2+)) phosphors were synthesized and systematically optimized, and their photoluminescence (PL) properties were evaluated. Depending upon the amount of Mg added, the emission efficiency of the phosphors could be enhanced. The substitution of Eu(2+) affected their maximum wavelength (lambda(max)) and thermal stability because the substitution site of Eu(2+) could be varied. To obtain single-phase two-color-emitting phosphors, we incorporated Mn(2+) into CMP:Eu(2+) phosphors. Weak red emission resulting from the forbidden transition of Mn(2+) could be enhanced by the energy transfer from Eu(2+) to Mn(2+) that occurs because of the spectral overlap between the photoluminescence excitation (PLE) spectrum of Mn(2+) and the PL spectrum of Eu(2+). The energy transfer process was confirmed by the luminescence spectra, energy transfer efficiency, and decay curve of the phosphors. Finally, the optimized Ca(6-x-y)Mg(x-z)(PO(4))(4):Eu(y)(2+),Mn(z)(2+) (CMP:Eu(2+),Mn(2+)) phosphors were applied with green emitting Ca(2)MgSi(2)O(7):Eu(2+) (CMS:Eu(2+)) phosphors to ultraviolet (UV) light emitting diode (LED)-pumped white LEDs. The CMS:Eu(2+)-mixed CMP:Eu(2+), Mn(2+)-based white LEDs showed an excellent color rendering index (CRI) of 98 because of the broader emission band and more stable color coordinates than those of commercial Y(3)Al(5)O(12):Ce(3+) (YAG:Ce(3+))-based white LEDs under a forward bias current of 20 mA. The fabricated white LEDs showed very bright natural white light that had the color coordinate of (0.3288, 0.3401), and thus CMP:Eu(2+),Mn(2+) could be regarded as a good candidate for UV LED-based white LEDs.

  15. 近紫外光-AgCl体系脱色处理活性艳红K-2BP染料废水%Treatment for Decoloring Reactive Brilliant Red K-2BP Dye Wastewater By Near UV-AgCl

    Institute of Scientific and Technical Information of China (English)

    孙琪娟

    2011-01-01

    以近紫外光为光源,AgCl为催化剂,考查了染料初始浓度、催化剂用量、pH值、不同光源等因素对活性艳红K-2BP染料废水脱色的影响.结果表明,当染料初始浓度为50mg/L,催化剂浓度为1000mg/L,pH值为4.0时,活性艳红K-2BP模拟染料废水脱色率达到72.1%.在该工艺条件下,用于实际染料废水,脱色效果也很明显.在此基础上,建立了活性艳红K-2BP降解的动力学方程,分析了活性艳红K-2BP降解机制,确定了K-2BP降解过程中一些被取代的芳香化合物的结构组成以及反应的中间产物和最终产物,并由此推测出其降解路线.%The dye wasterwater has some unique features: high CODCry high intensity of color, high salinity, hard to degradation, great changes in water quality and quantity and so on. It becomes oxidation resistant and anti-bio-degradable, which makes it difficult to be treated. The general aim of treatment is to remove COD and to decolor, which is more difficult. Color is the most important indicator to chock whether the printing and dyeing wastewater treatment can meet the emission standards. With the traditional method of wastewater treatment to hydrophilic or water-soluble dye wastewater, the decoloring effect is not satisfactory. The biological decoloring is less effective, while the physical and chemical decoloring does cost much. This paper is to find a simple, economical as well as effective way of decoloring printing and dyeing wastewater. Photocatalytic oxidation can be done in an ordinary condition (normal temperature,atmospheric pressure), but with strong oxidizing ability, with a great speed and without secondary pollution. In the water treatment domain, the AOP technology is widely used in environmental protection. Currently TiO2 is used as the photocatalytic oxidation catalyst,with the ultraviolet ray as the light source, mostly in a man-made form. Its use is limited because of its large energy consumption and poor efficiency in

  16. A CATALOG OF GALEX ULTRAVIOLET EMISSION FROM SPECTROSCOPICALLY CONFIRMED M DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Jones, David O. [Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); West, Andrew A., E-mail: djones@pha.jhu.edu [Astronomy Department of Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States)

    2016-01-20

    We present a catalog of Galaxy Evolution Explorer Near-UV (NUV) and Far-UV (FUV) photometry for the Palomar/MSU and SDSS DR7 spectroscopic M dwarf catalogs. The catalog contains NUV measurements matched to 577 spectroscopically confirmed M dwarfs and FUV measurements matched to 150 spectroscopically confirmed M dwarfs. Using these data, we find that NUV and FUV luminosities strongly correlate with Hα emission, a typical indicator of magnetic activity in M dwarfs. We also examine the fraction of M dwarfs with varying degrees of strong line emission at NUV wavelengths. Our results indicate that the frequency of M dwarf NUV emission peaks at intermediate spectral types, with at least ∼30% of young M4–M5 dwarfs having some level of activity. For mid-type M dwarfs, we show that NUV emission decreases with distance from the Galactic plane, a proxy for stellar age. Our complete matched source catalog is available online.

  17. Hydrogen Spectrum

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    The series of absorption or emission lines that are characteristic of the hydrogen atom. According to the Bohr theory of the hydrogen atom, devised by Danish physicist Neils Bohr (1885-1962) in 1913, the hydrogen atom can be envisaged as consisting of a central nucleus (a proton) around which a single electron revolves. The electron is located in one of a number of possible permitted orbits, each...

  18. Controlled Energy Transfer from a Ligand to an Eu(III) Ion: A Unique Strategy To Obtain Bright-White-Light Emission and Its Versatile Applications.

    Science.gov (United States)

    Boddula, Rajamouli; Singh, Kasturi; Giri, Santanab; Vaidyanathan, Sivakumar

    2017-09-05

    A new diphenylamine-functionalized ancillary-ligand-coordinated europium(III) β-diketonate complex showed incomplete photoexcitation energy transfer from a ligand to a Eu(III) ion. A solvatochromism study led to a balancing of the primary colors to obtain single-molecule white-light emission. Thermal-sensing analysis of the europium complex was executed. The europium complex, conjugated with a near-UV-light-emitting diode (395 nm), showed appropriate white-light-emission CIE color coordinates (x = 0.34 and y = 0.33) with a 5152 K correlated color temperature.

  19. A spectrum of an extrasolar planet.

    Science.gov (United States)

    Richardson, L Jeremy; Deming, Drake; Horning, Karen; Seager, Sara; Harrington, Joseph

    2007-02-22

    Of the over 200 known extrasolar planets, 14 exhibit transits in front of their parent stars as seen from Earth. Spectroscopic observations of the transiting planets can probe the physical conditions of their atmospheres. One such technique can be used to derive the planetary spectrum by subtracting the stellar spectrum measured during eclipse (planet hidden behind star) from the combined-light spectrum measured outside eclipse (star + planet). Although several attempts have been made from Earth-based observatories, no spectrum has yet been measured for any of the established extrasolar planets. Here we report a measurement of the infrared spectrum (7.5-13.2 microm) of the transiting extrasolar planet HD 209458b. Our observations reveal a hot thermal continuum for the planetary spectrum, with an approximately constant ratio to the stellar flux over this wavelength range. Superposed on this continuum is a broad emission peak centred near 9.65 microm that we attribute to emission by silicate clouds. We also find a narrow, unidentified emission feature at 7.78 microm. Models of these 'hot Jupiter' planets predict a flux peak near 10 microm, where thermal emission from the deep atmosphere emerges relatively unimpeded by water absorption, but models dominated by water fit the observed spectrum poorly.

  20. Fission Spectrum

    Science.gov (United States)

    Bloch, F.; Staub, H.

    1943-08-18

    Measurements of the spectrum of the fission neutrons of 25 are described, in which the energy of the neutrons is determined from the ionization produced by individual hydrogen recoils. The slow neutrons producing fission are obtained by slowing down the fast neutrons from the Be-D reaction of the Stanford cyclotron. In order to distinguish between fission neutrons and the remaining fast cyclotron neutrons both the cyclotron current and the pusle amplifier are modulated. A hollow neutron container, in which slow neutrons have a lifetime of about 2 milliseconds, avoids the use of large distances. This method results in much higher intensities than the usual modulation arrangement. The results show a continuous distribution of neutrons with a rather wide maximum at about 0.8 MV falling off to half of its maximum value at 2.0 MV. The total number of netrons is determined by comparison with the number of fission fragments. The result seems to indicate that only about 30% of the neutrons have energies below .8 MV. Various tests are described which were performed in order to rule out modification of the spectrum by inelastic scattering. Decl. May 4, 1951

  1. Broad-band spectrophotometry of HAT-P-32 b: search for a scattering signature in the planetary spectrum

    Science.gov (United States)

    Mallonn, M.; Bernt, I.; Herrero, E.; Hoyer, S.; Kirk, J.; Wheatley, P. J.; Seeliger, M.; Mackebrandt, F.; von Essen, C.; Strassmeier, K. G.; Granzer, T.; Künstler, A.; Dhillon, V. S.; Marsh, T. R.; Gaitan, J.

    2016-11-01

    Multicolour broad-band transit observations offer the opportunity to characterize the atmosphere of an extrasolar planet with small- to medium-sized telescopes. One of the most favourable targets is the hot Jupiter HAT-P-32 b. We combined 21 new transit observations of this planet with 36 previously published light curves for a homogeneous analysis of the broad-band transmission spectrum from the Sloan u' band to the Sloan z' band. Our results rule out cloud-free planetary atmosphere models of solar metallicity. Furthermore, a discrepancy at reddest wavelengths to previously published results makes a recent tentative detection of a scattering feature less likely. Instead, the available spectral measurements of HAT-P-32 b favour a completely flat spectrum from the near-UV to the near-IR. A plausible interpretation is a thick cloud cover at high altitudes.

  2. Broad-band spectrophotometry of HAT-P-32 b: Search for a scattering signature in the planetary spectrum

    CERN Document Server

    Mallonn, M; Herrero, E; Hoyer, S; Kirk, J; Wheatley, P J; Seeliger, M; Mackebrandt, F; von Essen, C; Strassmeier, K G; Granzer, T; Künstler, A; Dhillon, V S; Marsh, T R; Gaitan, J

    2016-01-01

    Multi-colour broad-band transit observations offer the opportunity to characterise the atmosphere of an extrasolar planet with small- to medium-sized telescopes. One of the most favourable targets is the hot Jupiter HAT-P-32 b. We combined 21 new transit observations of this planet with 36 previously published light curves for a homogeneous analysis of the broad-band transmission spectrum from the Sloan u' band to the Sloan z' band. Our results rule out cloud-free planetary atmosphere models of solar metallicity. Furthermore, a discrepancy at reddest wavelengths to previously published results makes a recent tentative detection of a scattering feature less likely. Instead, the available spectral measurements of HAT-P-32 b favour a completely flat spectrum from the near-UV to the near-IR. A plausible interpretation is a thick cloud cover at high altitudes.

  3. Near-UV absorption in very cool DA white dwarfs

    CERN Document Server

    Saumon, D; Kowalski, P M

    2014-01-01

    The atmospheres of very cool, hydrogen-rich white dwarfs (Teff <6000 K) are challenging to models because of the increased complexity of the equation of state, chemical equilibrium, and opacity sources in a low-temperature, weakly ionized dense gas. In particular, many models that assume relatively simple models for the broadening of atomic levels and mostly ideal gas physics overestimate the flux in the blue part of their spectra. A solution to this problem that has met with some success is that additional opacity at short wavelengths comes for the extreme broadening of the Lyman alpha line of atomic H by collisions primarily with H2. For the purpose of validating this model more rigorously, we acquired Hubble Space Telescope STIS spectra of 8 very cool white dwarfs (5 DA and 3 DC stars). Combined with their known parallaxes, BVRIJHK and Spitzer IRAC photometry, we analyze their entire spectral energy distribution (from 0.24 to 9.3 micron) with a large grid of model atmospheres and synthetic spectra. We f...

  4. Color discrimination in halobacteria: spectroscopic characterization of a second sensory receptor covering the blue-green region of the spectrum.

    Science.gov (United States)

    Wolff, E K; Bogomolni, R A; Scherrer, P; Hess, B; Stoeckenius, W

    1986-10-01

    Halobacterium halobium is attracted by green and red light and repelled by blue-green and shorter wavelength light. a photochromic, rhodopsin-like protein in the cell membrane, sensory rhodopsin sR587, has been identified as the receptor for the long-wavelength and near-UV stimuli. Discrepancies between the action spectrum for the repellent effect of blue light and the absorption spectrum of sR587 and its photocycle intermediate S373 strongly suggest the existence of an additional photoreceptor for the blue region of the spectrum. Transient light-induced absorbance changes in intact cells and cell membranes show, in addition to sR587, the presence of a second photoactive pigment with maximal absorption near 480 nm. It undergoes a cyclic photoreaction with a half-time of 150 msec. One intermediate state with maximal absorption near 360 nm has been resolved. The spectral properties of the new pigment are consistent with a function as the postulated photoreceptor for the repellent effect of blue light. The phototactic reactions and both pigments are absent when retinal synthesis is blocked; both can be restored by the addition of retinal. These results confirm and extend similar observations by Takahashi et al. [Takahashi, T., Tomioka, H., Kamo, N. & Kobatake, Y. (1985) FEMS Microbiol. Lett. 28, 161-164]. The archaeobacterium H. halobium thus uses two different mechanisms for color discrimination; it uses two rhodopsin-like receptors with different spectral sensitivities and also the photochromicity of at least one of these receptors to distinguish between three regions covering the visible and near-UV spectrum.

  5. Spectrum Trading for Efficient Spectrum Utilization

    Directory of Open Access Journals (Sweden)

    Cong Xiong

    2014-04-01

    Full Text Available The conventional command and control based spectrum management has led to substantial underutilization of some spectrum bands while severely crowding others due to the uneven and dynamic needs that vary over time and at different locations. Spectrum trading has emerged as a promising management approach to substantially improve spectrum utilization and user experience in wireless communications by taking advantage of market-based mechanisms. This article presents an overview of spectrum trading, including the fundamental characteristics of spectrum trading markets, the state-of-the-art techniques for modeling and resolving various spectrum trading issues, and trading based dynamic spectrum sharing and access. Moreover, some open issues in spectrum trading are identified for future research in this area.

  6. Seyfert 1 composite spectrum using SDSS Legacy survey data

    Science.gov (United States)

    Pol, Nihan; Wadadekar, Yogesh

    2017-02-01

    We present a rest-frame composite spectrum for Seyfert 1 galaxies using spectra obtained from the 12th Data Release of the Sloan Digital Sky Survey. The spectrum is constructed by combining data from a total of 10112 galaxies, spanning a redshift range of 0-0.793. We produce an electronic table of the median and geometric mean composite Seyfert 1 spectrum. We measure the spectral index of the composite spectrum, and compare it with that of the composite quasar spectrum. We also measure the flux and width of the strong emission lines present in the composite spectrum. We compare the entire spectrum with the quasar spectrum in the context of the unification model for active galactic nuclei. The two composite spectra match extremely well in the blue part of the spectrum, while there is an offset in flux in the red portion of the spectrum.

  7. On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main-sequence stars

    Science.gov (United States)

    Mendigutía, I.; Oudmaijer, R. D.; Rigliaco, E.; Fairlamb, J. R.; Calvet, N.; Muzerolle, J.; Cunningham, N.; Lumsden, S. L.

    2015-09-01

    Correlations between the accretion luminosity and emission line luminosities (Lacc and Lline) of pre-main-sequence (PMS) stars have been published for many different spectral lines, which are used to estimate accretion rates. Despite the origin of those correlations is unknown, this could be attributed to direct or indirect physical relations between the emission line formation and the accretion mechanism. This work shows that all (near-UV/optical/near-IR) Lacc-Lline correlations are the result of the fact that the accretion luminosity and the stellar luminosity (L*) are correlated, and are not necessarily related with the physical origin of the line. Synthetic and observational data are used to illustrate how the Lacc-Lline correlations depend on the Lacc-L* relationship. We conclude that because PMS stars show the Lacc-L* correlation immediately implies that Lacc also correlates with the luminosity of all emission lines, for which the Lacc-Lline correlations alone do not prove any physical connection with accretion but can only be used with practical purposes to roughly estimate accretion rates. When looking for correlations with possible physical meaning, we suggest that Lacc/L* and Lline/L* should be used instead of Lacc and Lline. Finally, the finding that Lacc has a steeper dependence on L* for T Tauri stars than for intermediate-mass Herbig Ae/Be stars is also discussed. That is explained from the magnetospheric accretion scenario and the different photospheric properties in the near-UV.

  8. The spectrum of a single photoionized cloud

    CERN Document Server

    Ferland, G J

    2003-01-01

    The emission-line spectrum of a quasar is most likely emitted by an ensemble of photoionized clouds moving with a variety of velocities, with a range of densities and distances from the central object. The state of the art in this field is to first compute the emission from a single cloud, and then prescribe a mix of clouds to reproduce line intensities, profiles, and reverberation lags. Here I review the parameters that de-fine emission from a single cloud and the outstanding problems in qua-sar emission-line analysis.

  9. Behavior of the x-ray spectrum of multiply charged ions during forced plasma expansion

    Energy Technology Data Exchange (ETDEWEB)

    Zhidkov, A.G.; Marchenko, V.S.

    1982-07-01

    The behavior of the x-ray emission spectrum of a dense plasma during forced expansion is studied. The optical transparency of the plasma varies during the expansion. The plasma emission spectrum integrated over the expansion time is calculated from the analytic solutions of the equations. The intensity of the line emission is calculated in the average-ion approximation.

  10. rf excited optical emission spectrum of radicals generated during hot wire chemical vapour deposition for the preparation of microcrystalline silicon thin film%射频激发热丝化学气相沉积制备硅薄膜过程中光发射谱的研究

    Institute of Scientific and Technical Information of China (English)

    李天微; 刘丰珍; 朱美芳

    2011-01-01

    To study the radicals behavior in the hot wire chemical vapour deposition (HWCVD) process for the preparation of microcrystalline Si (μc-Si: H) thin film, a weak radio frequency (rf) power was introduced to excite the radicals generated in HWCVD chamber. The spectrum of fi-excited HWCVD (rf-HWCVD) was obtained by subtracting the emission of hot wires from the spectrum measured by OES. The influence of the rf power on the rf-HWCVD spectrum can be neglected as the rf power density was less than 0. 1 W/cm2. Under the same deposition parameters, the emission spectra for rf-HWCVD and plasma enhanced CVD (PECVD) processes are different. Under the low deposition pressure ( 7.5 Pa), the intensities of Sill * and Hα vary with the hot wire temperature reversely, which is characteristic of HWCVD with high gas dissociation rate and high concentration of atomic H. The ratio of intensity of Hα to Sill * in the emission spectrum of rf-HWCVD varying with deposition pressure is consistent with the crystalline fraction of μc-Si: H film. The results indicate that the optical emission spectroscopy measurement is a suitable method for the investigation of the HWCVD process excited by a weak rf-power.%采用射频(rf)激发,在热丝化学气相沉积(HWCVD)制备微晶硅薄膜的过程中产生发光基元,测量了rf激发HWCVD(rf-HWCVD)的光发射谱,比较了相同工艺条件下rf-HWCVD和等离子体增强CVD(PECVD)的光发射谱,分析了rf功率、热丝温度和沉积气压对rf-HWCVD光发射谱的影响.结果表明,在射频功率<0.1W/cm1时,rf-HWCVD发射光谱反映了HWCVD高的气体分解效率和高浓度原子氢的特点,能够解释气压变化与微晶硅薄膜微结构的关系,是研究HWCVD气相过程的有效方法之一.

  11. Seyfert 1 Composite Spectrum using SDSS Legacy Survey Data

    CERN Document Server

    Pol, Nihan

    2016-01-01

    We present a rest-frame composite spectrum for Seyfert 1 galaxies using spectra obtained from the DR12 release of the Sloan Digital Sky Survey (SDSS). The spectrum is constructed by combining data from a total of 10,112 galaxies, spanning a redshift range of 0 to 0.793. We produce an electronic table of the median and geometric mean composite Seyfert 1 spectrum. We measure the spectral index of the composite spec- trum, and compare it with that of the composite quasar spectrum. We also measure the flux and width of the strong emission lines present in the composite spectrum. We compare the entire spectrum with the quasar spectrum in the context of the AGN unification model. The two composite spectra match extremely well in the blue part of the spectrum, while there is an offset in flux in the red portion of the spectrum.

  12. Emission Trading

    OpenAIRE

    2009-01-01

    The work concerns Emission Trading Scheme from perspektive of taxes and accounting. I should show problems with emission trading. The work concerns practical example of trading with emission allowance.

  13. CORA: Emission Line Fitting with Maximum Likelihood

    Science.gov (United States)

    Ness, Jan-Uwe; Wichmann, Rainer

    2011-12-01

    CORA analyzes emission line spectra with low count numbers and fits them to a line using the maximum likelihood technique. CORA uses a rigorous application of Poisson statistics. From the assumption of Poissonian noise, the software derives the probability for a model of the emission line spectrum to represent the measured spectrum. The likelihood function is used as a criterion for optimizing the parameters of the theoretical spectrum and a fixed point equation is derived allowing an efficient way to obtain line fluxes. CORA has been applied to an X-ray spectrum with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra observatory.

  14. Probing the Absorption and Emission Transition Dipole Moment of DNA Stabilized Silver Nanoclusters

    DEFF Research Database (Denmark)

    Hooley, Emma Nicole; Carro Temboury, Miguel R.; Vosch, Tom André Jos

    2017-01-01

    Using single molecule polarization measurements, we investigate the excitation and emission polarization characteristics of DNA stabilized silver nanoclusters (C24-AgNCs). Although small changes in the polarization generally accompany changes to the emission spectrum, the emission and excitation ...

  15. Thermospheric emissions of the early Earth

    Science.gov (United States)

    Bernard, D.; Barthélémy, M.; Gronoff, G.; Ménager, H.; Lilensten, J.

    2012-09-01

    The aim of this work is to examine the thermospheric emission of the Earth over its history. In this first step, we adapt a kinetic transport code developed for different planets of the Solar System to the first atmosphere of the Earth. We take into account the possible changes in the solar emission spectrum to compute the diurnal ionizations, excitations and dissociations. We deduce a thermospheric spectrum averaged over the planet. The effect of solar wind electron precipitation is also considered.

  16. 激光诱导AlO自由基B2Σ+-X 2Σ+跃迁光谱研究%Study on the emission spectrum of AlO radical B2Σ+-X 2Σ+transition using laser-induced breakdown spectroscopy

    Institute of Scientific and Technical Information of China (English)

    郭连波; 郝荣飞; 郝中骐; 李阔湖; 沈萌; 任昭; 李祥友; 曾晓雁

    2013-01-01

    基于激光诱导击穿光谱技术,利用Nd:YAG脉冲激光激发Al2O3(含量为99%)陶瓷片产生等离子体,获得了AlO自由基B2Σ+-X 2Σ+跃迁的33条发射谱线。就AlO自由基光谱的时间演化规律和激光能量对谱线的影响规律进行了研究与分析。结果表明, AlO自由基光谱出现在Al原子和Al离子光谱之后,且持续时间较长。当激光的脉冲能量由10 mJ起不断增加时, AlO自由基光谱强度逐渐减小,且最大值出现时间随激光能量的增加而后移。在此基础上,进行了陶瓷等离子体在空气和氩气环境下的对比试验,发现从Al2 O3陶瓷片中激发所产生的AlO自由基必须有空气中O2参与反应。%Based on laser-induced breakdown spectroscopy, a short pulse laser is used to excite Al2O3 (content of 99%) ceramic to produce ceramic plasma. The plasma emission spectrum is collected, and 33 spectral lines of AlO radical B2Σ+-X 2Σ+transition are obtained. The time-resolved AlO radical spectrum and its relationship with laser pulse energy are investigated. The results show that the emission spectrum of AlO radical appears later and lasts longer than those of Al atom and Al ion. With the increase of the laser pulse energy, the spectral intensity of AlO radical decreases and the time when the maximum spectral intensity appears moves backward. Finally, the ceramic plasma produced in air is compared with that produced in Ar environment. The results prove that the formation of AlO radical spectrum has an important relationship with O2 in air.

  17. On Removing Interloper Contamination from Intensity Mapping Power Spectrum Measurements

    CERN Document Server

    Lidz, Adam

    2016-01-01

    Line intensity mapping experiments seek to trace large scale structure by measuring the spatial fluctuations in the combined emission, in some convenient spectral line, from individually unresolved galaxies. An important systematic concern for these surveys is line confusion from foreground or background galaxies emitting in other lines that happen to lie at the same observed frequency as the "target" emission line of interest. We develop an approach to separate this "interloper" emission at the power spectrum level. If one adopts the redshift of the target emission line in mapping from observed frequency and angle on the sky to co-moving units, the interloper emission is mapped to the wrong co-moving coordinates. Since the mapping is different in the line of sight and transverse directions, the interloper contribution to the power spectrum becomes anisotropic, especially if the interloper and target emission are at widely separated redshifts. This distortion is analogous to the Alcock-Paczynski test, but her...

  18. Emissions Trading

    NARCIS (Netherlands)

    Woerdman, Edwin; Backhaus, Juergen

    2014-01-01

    Emissions trading is a market-based instrument to achieve environmental targets in a cost-effective way by allowing legal entities to buy and sell emission rights. The current international dissemination and intended linking of emissions trading schemes underlines the growing relevance of this

  19. Emissions Trading

    NARCIS (Netherlands)

    Woerdman, Edwin; Backhaus, Juergen

    2014-01-01

    Emissions trading is a market-based instrument to achieve environmental targets in a cost-effective way by allowing legal entities to buy and sell emission rights. The current international dissemination and intended linking of emissions trading schemes underlines the growing relevance of this instr

  20. Flat radio-spectrum galaxies and BL Lacs I. Core properties

    NARCIS (Netherlands)

    Dennett-Thorpe, J; Marcha, MJ

    2000-01-01

    This paper concerns the relationship of BL Lacs and flat-spectrum weak emission-line galaxies. We compare the weak emission-line galaxies and the BL Lacs in a sample of 57 flat-spectrum objects (Marcha et al. 1996), using high-frequency radio and non-thermal optical flux densities, spectral indices

  1. Flat radio-spectrum galaxies and BL Lacs I. Core properties

    NARCIS (Netherlands)

    Dennett-Thorpe, J; Marcha, MJ

    This paper concerns the relationship of BL Lacs and flat-spectrum weak emission-line galaxies. We compare the weak emission-line galaxies and the BL Lacs in a sample of 57 flat-spectrum objects (Marcha et al. 1996), using high-frequency radio and non-thermal optical flux densities, spectral indices

  2. NON-Shock-Plasticity/Fracture Burst Acoustic-Emission(BAE) ``1''/f -``Noise'' Power-Spectrum(PS) Power-Law UNIVERSALITY is Merely F =ma Time-Series Integral-Transform, aka ``Bak'' -``SOC'' REdiscovery'' PRE(1687)-``Bak'' (1988)

    Science.gov (United States)

    Siegel, Edward

    2015-06-01

    NON-shock plasticity/fracture BAE[E.S.:MSE 8,310(71); PSS:(a)5,601/607(71); Xl.-Latt.Defects 5,277(74); Scripta Met.:6,785(72); 8,587/617(74); 3rd Tokyo AE Symp.(76); Acta Met. 5,383(77); JMMM 7,312(78)] ``1''/ ω-``noise'' power-spectrum ``pink''-Zipf(NOT ``red'' =Pareto) power-law UNIVERSALITY is manifestly-demonstrated in two distinct ways to be nothing but Newton 3rd Law of Motion F = ma REdiscovery!!! (aka ``Bak''(1988)-``SOC'':1687 0a<0) PS P(ω) = 1/ω 1 . 000 ... pink/flicker/HYPERBOLICITY.

  3. 47 CFR 90.669 - Emission limits.

    Science.gov (United States)

    2010-10-01

    ... MOBILE RADIO SERVICES Regulations Governing Licensing and Use of Frequencies in the 806-824, 851-869, 896... 896-901/935-940 Mhz Band § 90.669 Emission limits. (a) On any frequency in an MTA licensee's spectrum block that is adjacent to a non-MTA frequency, the power of any emission shall be attenuated below...

  4. Emission Facilities - Air Emission Plants

    Data.gov (United States)

    NSGIC Education | GIS Inventory — Represents the Primary Facility type Air Emission Plant (AEP) point features. Air Emissions Plant is a DEP primary facility type related to the Air Quality Program....

  5. Emission Facilities - Air Emission Plants

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — Represents the Primary Facility type Air Emission Plant (AEP) point features. Air Emissions Plant is a DEP primary facility type related to the Air Quality Program....

  6. Emission inventory; Inventaire des emissions

    Energy Technology Data Exchange (ETDEWEB)

    Fontelle, J.P. [CITEPA, Centre Interprofessionnel Technique d`Etudes de la Pollution Atmospherique, 75 - Paris (France)

    1997-12-31

    Statistics on air pollutant (sulfur dioxide, nitrogen oxides and ammonium) emissions, acid equivalent emissions and their evolution since 1990 in the various countries of Europe and the USA, are presented. Emission data from the industrial, agricultural, transportation and power sectors are given, and comparisons are carried out between countries based on Gnp and population, pollution import/export fluxes and compliance to the previous emission reduction objectives

  7. The long wavelength emission of interstellar PAHs: characterizing the spinning dust emission

    CERN Document Server

    Ysard, Nathalie

    2009-01-01

    The emission of cold dust grains at long wavelengths will soon be observed by the Planck and Herschel satellites and provide new constraints on the nature of interstellar dust. The microwave anomalous emission, proposed to be due to spinning PAHs, should help to better define these species. Moreover, understanding the fluctuations of the anomalous emission over the sky is crucial for CMB studies. We focus on the long wavelength emission of interstellar PAHs in their rovibrational and rotational transitions. The PAH emission spectrum from the IR to the microwave range is presented and compared to anomalous emission observations. To model their long wavelength emission, we treat PAHs as isolated systems and follow consistently their IR and rotational emissions. We consider several interstellar phases and discuss how the anomalous emission may constrain their size distribution. Our model of PAH emission accounts for the mid-IR spectra of the diffuse interstellar medium and of the Orion Bar. For lambda<3mm the...

  8. Radio emission of the sun and planets

    CERN Document Server

    Zheleznyakov, V V

    1970-01-01

    International Series of Monographs in Natural Philosophy, Volume 25: Radio Emission of the Sun and Planets presents the origin of the radio emission of the planets. This book examines the outstanding triumphs achieved by radio astronomy of the solar system. Comprised of 10 chapters, this volume begins with an overview of the physical conditions in the upper layers of the Sun, the Moon, and the planets. This text then examines the three characteristics of radio emission, namely, the frequency spectrum, the polarization, and the angular spectrum. Other chapters consider the measurements of the i

  9. Fundamental molecules of life are pigments which arose and evolved to dissipate the solar spectrum

    Science.gov (United States)

    Michaelian, K.; Simeonov, A.

    2015-02-01

    The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of today, oxygen and ozone derived from life processes are performing the short wavelength UVC and UVB dissipation. On Earth's surface, water and organic pigments in water facilitate the near UV and visible photon dissipation. The first organic pigments probably formed, absorbed, and dissipated at those photochemically active wavelengths in the UVC that could have reached Earth's surface during the Archean. Proliferation of these pigments can be understood as an autocatalytic photochemical process obeying non-equilibrium thermodynamic directives related to increasing solar photon dissipation rate. Under these directives, organic pigments would have evolved over time to increase the global photon dissipation rate by; (1) increasing the ratio of their effective photon cross sections to their physical size, (2) decreasing their electronic excited state life times, (3) quenching radiative de-excitation channels (e.g. fluorescence), (4) covering ever more completely the prevailing solar spectrum, and (5) proliferating and dispersing to cover an ever greater surface area of Earth. From knowledge of the evolution of the spectrum of G-type stars, and considering the most probable history of the transparency of Earth's atmosphere, we construct the most probable Earth surface solar spectrum as a function of time and compare this with the history of molecular absorption maxima obtained from the available data in the literature. This comparison supports the conjecture that many fundamental molecules of life are pigments which arose and evolved to dissipate the solar spectrum, supports the thermodynamic dissipation theory for the origin of life, constrains models for Earth's early atmosphere, and sheds some new light on the origin of

  10. Fundamental molecules of life are pigments which arose and evolved to dissipate the solar spectrum

    Directory of Open Access Journals (Sweden)

    K. Michaelian

    2015-02-01

    Full Text Available The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of today, oxygen and ozone derived from life processes are performing the short wavelength UVC and UVB dissipation. On Earth's surface, water and organic pigments in water facilitate the near UV and visible photon dissipation. The first organic pigments probably formed, absorbed, and dissipated at those photochemically active wavelengths in the UVC that could have reached Earth's surface during the Archean. Proliferation of these pigments can be understood as an autocatalytic photochemical process obeying non-equilibrium thermodynamic directives related to increasing solar photon dissipation rate. Under these directives, organic pigments would have evolved over time to increase the global photon dissipation rate by; (1 increasing the ratio of their effective photon cross sections to their physical size, (2 decreasing their electronic excited state life times, (3 quenching radiative de-excitation channels (e.g. fluorescence, (4 covering ever more completely the prevailing solar spectrum, and (5 proliferating and dispersing to cover an ever greater surface area of Earth. From knowledge of the evolution of the spectrum of G-type stars, and considering the most probable history of the transparency of Earth's atmosphere, we construct the most probable Earth surface solar spectrum as a function of time and compare this with the history of molecular absorption maxima obtained from the available data in the literature. This comparison supports the conjecture that many fundamental molecules of life are pigments which arose and evolved to dissipate the solar spectrum, supports the thermodynamic dissipation theory for the origin of life, constrains models for Earth's early atmosphere, and sheds some new light on the origin of

  11. Steep Spectrum Radio Sources in Galaxy Clusters

    Science.gov (United States)

    Clarke, Tracy E.

    2012-05-01

    Steep spectrum radio emission associated with galaxy clusters comes from compact central active galactic nuclei (AGN) driven radio sources in dense cool core clusters as well as from large regions of diffuse (halo and relic) emission associated with dynamically complex merging systems. These radio halos and relics are best traced at low radio frequencies where details of their morphology, location and spectral index distribution can be used to probe the underlying acceleration mechanism(s) as well as important details of large scale structure formation. Low frequency radio observations also play an important role in the study of AGN feedback into the intracluster medium and the regulation of cooling cores. While spectacular results are coming from the current generation of low frequency instruments, there will soon be a new revolution in studies of steep spectrum sources with the upcoming generation of low frequency interferometers on Earth and ultimately the moon.

  12. Nonlinear photoluminescence spectrum of single gold nanostructures.

    Science.gov (United States)

    Knittel, Vanessa; Fischer, Marco P; de Roo, Tjaard; Mecking, Stefan; Leitenstorfer, Alfred; Brida, Daniele

    2015-01-27

    We investigate the multiphoton photoluminescence characteristics of gold nanoantennas fabricated from single crystals and polycrystalline films. By exciting these nanostructures with ultrashort pulses tunable in the near-infrared range, we observe distinct features in the broadband photoluminescence spectrum. By comparing antennas of different crystallinity and shape, we demonstrate that the nanoscopic geometry of plasmonic devices determines the shape of the emission spectra. Our findings rule out the contribution of the gold band structure in shaping the photoluminescence.

  13. Compact Microwave Fourier Spectrum Analyzer

    Science.gov (United States)

    Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

    2009-01-01

    A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.

  14. Autism Spectrum Disorder (ASD)

    Science.gov (United States)

    ... Español (Spanish) Recommend on Facebook Tweet Share Compartir Autism spectrum disorder (ASD) is a developmental disability that can cause ... factors that may put children at risk for autism spectrum disorder (ASD) and other developmental disabilities. More E-mail ...

  15. The CMBR spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Stebbins, A.

    1997-05-01

    Here we give an introduction to the observed spectrum of the Cosmic Microwave Background Radiation (CMBR) and discuss what can be learned about it. Particular attention will be given to how Compton scattering can distort the spectrum of the CMBR. An incomplete bibliography of relevant papers is also provided.

  16. 5G Spectrum Sharing

    OpenAIRE

    Nekovee, Maziar; Rudd, Richard

    2017-01-01

    In this paper an overview is given of the current status of 5G industry standards, spectrum allocation and use cases, followed by initial investigations of new opportunities for spectrum sharing in 5G using cognitive radio techniques, considering both licensed and unlicensed scenarios. A particular attention is given to sharing millimeter-wave frequencies, which are of prominent importance for 5G.

  17. Fetal Alcohol Spectrum Disorder

    Science.gov (United States)

    Caley, Linda M.; Kramer, Charlotte; Robinson, Luther K.

    2005-01-01

    Fetal alcohol spectrum disorder (FASD) is a serious and widespread problem in this country. Positioned within the community with links to children, families, and healthcare systems, school nurses are a critical element in the prevention and treatment of those affected by fetal alcohol spectrum disorder. Although most school nurses are familiar…

  18. Wave Reflection Coefficient Spectrum

    Institute of Scientific and Technical Information of China (English)

    俞聿修; 邵利民; 柳淑学

    2003-01-01

    The wave reflection coefficient frequency spectrum and directional spectrum for concrete face slope breakwaters and rubble mound breakwaters are investigated through physical model tests in the present study. The reflection coefficients of oblique irregular waves are analyzed by the Modified Two-Point Method (MTPM) proposed by the authors. The results show that the wave reflection coefficient decreases with increasing wave frequency and incident angle or decreasing structure slope. The reflection coefficient frequency spectrum and its variation with Iribarren number are given in this paper. The paper also suggests an empirical 3-dimensional reflection coefficient spectrum, i.e. reflection coefficient directional spectrum, which can be used to illustrate quantitatively the variation of reflection coefficient with the incident angle and the Iribarren number for oblique irregular waves.

  19. Experimental determination of the antineutrino spectrum of the fission products of {sup 238}U

    Energy Technology Data Exchange (ETDEWEB)

    Haag, Nils-Holger

    2013-10-09

    Fission of {sup 238}U contributes about 10 % to the antineutrino emission of a pressurized water reactor. In the present thesis, the beta spectrum of the fission products of {sup 238}U was determined in an experiment at the neutron source FRM II. This beta spectrum was subsequently converted into an antineutrino spectrum. This first measurement of the antineutrino spectrum supports all current and future reactor antineutrino experiments.

  20. Polarized Emission from Interstellar Dust

    CERN Document Server

    Vaillancourt, J E

    2006-01-01

    Observations of far-infrared (FIR) and submillimeter (SMM) polarized emission are used to study magnetic fields and dust grains in dense regions of the interstellar medium (ISM). These observations place constraints on models of molecular clouds, star-formation, grain alignment mechanisms, and grain size, shape, and composition. The FIR/SMM polarization is strongly dependent on wavelength. We have attributed this wavelength dependence to sampling different grain populations at different temperatures. To date, most observations of polarized emission have been in the densest regions of the ISM. Extending these observations to regions of the diffuse ISM, and to microwave frequencies, will provide additional tests of grain and alignment models. An understanding of polarized microwave emission from dust is key to an accurate measurement of the polarization of the cosmic microwave background. The microwave polarization spectrum will put limits on the contributions to polarized emission from spinning dust and vibrat...

  1. Probability-consistent spectrum and code spectrum

    Institute of Scientific and Technical Information of China (English)

    沈建文; 石树中

    2004-01-01

    In the seismic safety evaluation (SSE) for key projects, the probability-consistent spectrum (PCS), usually obtained from probabilistic seismic hazard analysis (PSHA), is not consistent with the design response spectrum given by Code for Seismic Design of Buildings (GB50011-2001). Sometimes, there may be a remarkable difference between them. If the PCS is lower than the corresponding code design response spectrum (CDS), the seismic fortification criterion for the key projects would be lower than that for the general industry and civil buildings. In the paper, the relation between PCS and CDS is discussed by using the ideal simple potential seismic source. The results show that in the most areas influenced mainly by the potential sources of the epicentral earthquakes and the regional earthquakes, PCS is generally lower than CDS in the long periods. We point out that the long-period response spectra of the code should be further studied and combined with the probability method of seismic zoning as much as possible. Because of the uncertainties in SSE, it should be prudent to use the long-period response spectra given by SSE for key projects when they are lower than CDS.

  2. Mining Study of Oil Atomic Emission Spectrum Data of Certain Diesel Engine%某型柴油机润滑油发射光谱数据挖掘研究*

    Institute of Scientific and Technical Information of China (English)

    张乔斌; 张春辉; 朱爱芳

    2014-01-01

    Atomic emission spectroscopy is one of the most widely used techniques for oil analysis in the world now .In order to deeply mine the relation between the concentration of wearing elements of diesel engine and its loads ,cylinders'clearances and runtime after renewing oil ,a simulation model and a prediction model of Fe concentration of a type of six cyl‐inder diesel engine are established by applying neural network .The engine set up seven different working conditions and measured concentration of sixty‐nine oil samples .The results show that the relative errors of the simulation value of the 69 samples are within less than 15% .The absolute errors of prediction value of the 19 samples are lower than the acceptable ac‐curacy indices and the relative errors of 84% samples are within 15% .It is proved that Fe concentration can be predicted ef‐fectively by Neural Network algorithm .%油料原子发射光谱仪是目前国内外广泛应用的油液分析技术之一。为了深入挖掘某型柴油机润滑油中磨损元素的浓度与柴油机负荷、气缸间隙和运行时间之间的对应关系,应用神经网络建立了某型六缸柴油机主要磨损元素 Fe的浓度仿真模型和预测模型。柴油机设置了7种工况,测量了69个油样。仿真模型中,69个油样仿真值的相对误差均小于15%;预测模型中,19个油样预测值的绝对误差均小于光谱仪精确度值,且84%的油样预测值的相对误差小于15%。预测结果表明:神经网络算法能较好地预测Fe元素浓度。

  3. Anti-Stokes emissions and determination of Stark sub-level diagram of Er{sup 3+} ions in KY{sub 3}F{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Boulma, E [Laboratoire d' Energetique et d' Optique, UTAP, Universite de Reims Champagne-Ardenne, BP 1039, Reims Cedex 51 687 (France); Diaf, M [Departement de Physique, Universite Badji Mokhtar Annaba, BP12, 23000 Annaba, Algerie (Germany); Jouart, J P [Laboratoire d' Energetique et d' Optique, UTAP, Universite de Reims Champagne-Ardenne, BP 1039, Reims Cedex 51 687 (France); Bouffard, M [Laboratoire d' Energetique et d' Optique, UTAP, Universite de Reims Champagne-Ardenne, BP 1039, Reims Cedex 51 687 (France); Doualan, J L [Centre Interdisciplinaire de Recherches Ions Lasers (CIRIL), UMR 6637 CNRS-CEA-ISMRA, ENSI de Caen, 6 Boulevard Marechal Juin, 14050 Caen Cedex (France); Moncorge, R [Centre Interdisciplinaire de Recherches Ions Lasers (CIRIL), UMR 6637 CNRS-CEA-ISMRA, ENSI de Caen, 6 Boulevard Marechal Juin, 14050 Caen Cedex (France)

    2006-07-26

    We are interested, in this work, in determining the Stark sub-level of Er{sup 3+} ions doping a KY{sub 3}F{sub 10} single crystal with a molar concentration of 1%. We have used a new method of measurement of energies of the ground level and emitting levels from excitation and anti-Stokes emission spectra recorded at liquid nitrogen temperature. This technique is based on a spectral analysis of the anti-Stokes emissions recorded after selective excitation with a red dye tunable laser. Thus, we could determine the Stark sub-levels of the ground and the principal emitting levels in the infrared, visible and near-UV ranges with a very good precision.

  4. Visible Spectrum Incandescent Selective Emitter

    Energy Technology Data Exchange (ETDEWEB)

    Sonsight Inc.

    2004-04-30

    The purpose of the work performed was to demonstrate the feasibility of a novel bi-layer selective emitter. Selective emitters are incandescent radiant bodies with emissivities that are substantially larger in a selected part of the radiation spectrum, thereby significantly shifting their radiated spectral distribution from that of a blackbody radiating at the same temperature. The major research objectives involved answering the following questions: (1) What maximum VIS/NIR radiant power and emissivity ratios can be attained at 2650 K? (2) What is the observed emitter body life and how does its performance vary with time? (3) What are the design tradeoffs for a dual heating approach in which both an internally mounted heating coil and electrical resistance self-heating are used? (4) What are the quantitative improvements to be had from utilizing a bi-layer emitter body with a low emissivity inner layer and a partially transmissive outer layer? Two approaches to obtaining selective emissivity were investigated. The first was to utilize large optical scattering within an emitter material with a spectral optical absorption that is much greater within the visible spectrum than that within the NIR. With this approach, an optically thick emitter can radiate almost as if optically thin because essentially, scattering limits the distance below the surface from which significant amounts of internally generated radiation can emerge. The performance of thin emitters was also investigated (for optically thin emitters, spectral emissivity is proportional to spectral absorptivity). These emitters were fabricated from thin mono-layer emitter rods as well as from bi-layer rods with a thin emitter layer mounted on a substrate core. With an initially estimated energy efficiency of almost three times that of standard incandescent bulbs, a number of energy, economic and environmental benefits such as less energy use and cost, reduced CO{sub 2} emissions, and no mercury contamination

  5. Ionized Outflows from Compact Steep Spectrum Sources

    CERN Document Server

    Shih, Hsin-Yi; Kewley, Lisa

    2013-01-01

    Massive outflows are known to exist, in the form of extended emission-line regions (EELRs), around about one-third of powerful FR II radio sources. We investigate the origin of these EELRs by studying the emission-line regions around compact-steep-spectrum (CSS) radio galaxies that are younger (10$^3$ to 10$^5$ years old) versions of the FR II radio galaxies. We have searched for and analyzed the emission-line regions around 11 CSS sources by taking integral field spectra using GMOS on Gemini North. We fit the [\\ion{O}{3}] $\\lambda 5007$ line and present the velocity maps for each detected emission-line region. We find, in most cases, that the emission-line regions have multi-component velocity structures with different velocity dispersions and/or flux distributions for each component. The velocity gradients of the emission-line gas are mostly well aligned with the radio axis, suggesting a direct causal link between the outflowing gas and the radio jets. The complex velocity structure may be a result of diffe...

  6. Absorptivity of brown carbon in fresh and photo-chemically aged biomass-burning emissions

    Directory of Open Access Journals (Sweden)

    R. Saleh

    2013-08-01

    Full Text Available Experiments were conducted to investigate light absorption of organic aerosol (OA in fresh and photo-chemically aged biomass-burning emissions. The experiments considered residential hardwood fuel (oak and fuels commonly consumed in wild-land and prescribed fires in the United States (pocosin pine and gallberry. Photo-chemical aging was performed in an environmental chamber. We constrained the effective light-absorption properties of the OA using conservative limiting assumptions, and found that both primary organic aerosol (POA in the fresh emissions and secondary organic aerosol (SOA produced by photo-chemical aging contain brown carbon, and absorb light to a significant extent. This work presents the first direct evidence that SOA produced in aged biomass-burning emissions is absorptive. For the investigated fuels, SOA is less absorptive than POA in the long visible, but exhibits stronger wavelength-dependence and is more absorptive in the short visible and near-UV. Light absorption by SOA in biomass-burning emissions might be an important contributor to the global radiative forcing budget.

  7. Absorptivity of brown carbon in fresh and photo-chemically aged biomass-burning emissions

    Directory of Open Access Journals (Sweden)

    R. Saleh

    2013-05-01

    Full Text Available Experiments were conducted to investigate light absorption of organic aerosol (OA in fresh and photo-chemically aged biomass-burning emissions. The experiments considered residential hardwood fuel (oak and fuels commonly consumed in wild-land and prescribed fires in the United States (pocosin pine and gallberry. Photo-chemical aging was performed in an environmental chamber. We constrained the light-absorption properties of the OA using conservative limiting assumptions, and found that both primary organic aerosol (POA in the fresh emissions and secondary organic aerosol (SOA produced by photo-chemical aging absorb light to a significant extent, and are categorized as brown carbon. This work presents the first direct evidence that SOA produced in aged biomass-burning emissions is absorptive. For the investigated fuels, SOA is less absorptive than POA in the long visible, but exhibits steeper wavelength-dependence (larger Absorption Ångström Exponent and is more absorptive in the short visible and near-UV. Light absorption by SOA in biomass-burning emissions might be an important contributor to the global radiative forcing budget.

  8. Stimulated emission of surface plasmon polaritons

    CERN Document Server

    Noginov, M A; Mayy, M F; Ritzo, B A; Noginova, N; Podolskiy, V A

    2008-01-01

    We have observed laser-like emission of surface plasmon polaritons (SPPs) decoupled to the glass prism in an attenuated total reflection setup. SPPs were excited by optically pumped molecules in a polymeric film deposited on the top of the silver film. Stimulated emission was characterized by a distinct threshold in the input-output dependence and narrowing of the emission spectrum. The observed stimulated emission and corresponding to it compensation of the metallic absorption loss by gain enables many applications of metamaterials and nanoplasmonic devices.

  9. The marine diversity spectrum

    DEFF Research Database (Denmark)

    Reuman, Daniel C.; Gislason, Henrik; Barnes, Carolyn

    2014-01-01

    of taxonomy (all the species in a region regardless of clade) are much less studied but are equally important and will illuminate a different set of ecological and evolutionary processes. We develop and test a mechanistic model of how diversity varies with body mass in marine ecosystems. The model predicts...... the form of the diversity spectrum', which quantifies the distribution of species' asymptotic body masses, is a species analogue of the classic size spectrum of individuals, and which we have found to be a new and widely applicable description of diversity patterns. The marine diversity spectrum...... is predicted to be approximately linear across an asymptotic mass range spanning seven orders of magnitude. Slope -0 center dot 5 is predicted for the global marine diversity spectrum for all combined pelagic zones of continental shelf seas, and slopes for large regions are predicted to lie between -0 center...

  10. Fast Spectrum Reactors

    CERN Document Server

    Todd, Donald; Tsvetkov, Pavel

    2012-01-01

    Fast Spectrum Reactors presents a detailed overview of world-wide technology contributing to the development of fast spectrum reactors. With a unique focus on the capabilities of fast spectrum reactors to address nuclear waste transmutation issues, in addition to the well-known capabilities of breeding new fuel, this volume describes how fast spectrum reactors contribute to the wide application of nuclear power systems to serve the global nuclear renaissance while minimizing nuclear proliferation concerns. Readers will find an introduction to the sustainable development of nuclear energy and the role of fast reactors, in addition to an economic analysis of nuclear reactors. A section devoted to neutronics offers the current trends in nuclear design, such as performance parameters and the optimization of advanced power systems. The latest findings on fuel management, partitioning and transmutation include the physics, efficiency and strategies of transmutation, homogeneous and heterogeneous recycling, in addit...

  11. Is the Galactic Cosmic Ray Spectrum Constant in Time?

    CERN Document Server

    Eichler, David; Pohl, Martin

    2013-01-01

    The hypothesis is considered that the present Galactic cosmic ray spectrum is at present softer than its time average due to source intermittency. Measurements of muogenic nuclides underground could provide an independent measurement of the time averaged spectrum. Source intermittency could also account for the surprising low anisotropy reported by the IceCube collaboration. Predictions for Galactic emission of ultrahigh-energy quanta, such as UHE gamma rays and neutrinos, might be higher or lower than previously estimated.

  12. Spectrum and network measurements

    CERN Document Server

    Witte, Robert A

    2014-01-01

    This new edition of Spectrum and Network Measurements enables readers to understand the basic theory, relate it to measured results, and apply it when creating new designs. This comprehensive treatment of frequency domain measurements successfully consolidates all the pertinent theory into one text. It covers the theory and practice of spectrum and network measurements in electronic systems. It also provides thorough coverage of Fourier analysis, transmission lines, intermodulation distortion, signal-to-noise ratio and S-parameters.

  13. Infrared emission from M31

    Science.gov (United States)

    Habing, H. J.; Miley, G.; Young, E.; Baud, B.; Boggess, N.; Clegg, P. E.; Harris, S.; Rowan-Robinson, M.; De Jong, T.; Raimond, E.

    1984-01-01

    Maps of M31 have been obtained at wavelengths of 12, 25, 60, and 100 microns. Emission is detected from the center and from a ring of 50 arcmin radius. The ring is that also seen in H I, in H II, and in radio continuum radiation. The spectrum of the central emission suggests a hotter dust temperature than in the ring. M31 is a weak infrared source, the radiation measured longward of 12 microns being only 3 percent of its total luminosity. The two closest companion galaxies, M32 and NGC 205, have also been detected.

  14. Black hole quantum spectrum

    National Research Council Canada - National Science Library

    Corda, Christian

    2013-01-01

    Introducing a black hole (BH) effective temperature, which takes into account both the non-strictly thermal character of Hawking radiation and the countable behavior of emissions of subsequent Hawking quanta, we recently re...

  15. Spectral and surface investigations of Ca{sub 2}V{sub 2}O{sub 7}:Eu{sup 3+} nanophosphors prepared by citrate-gel combustion method: a potential red-emitting phosphor for near-UV light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinay [Shri Mata Vaishno Devi University, School of Physics, Katra, J and K (India); University of the Free State, Department of Physics, P.O. Box 339, Bloemfontein (South Africa); Bedyal, A.K.; Sharma, J. [Shri Mata Vaishno Devi University, School of Physics, Katra, J and K (India); Kumar, V.; Ntwaeaborwa, O.M.; Swart, H.C. [University of the Free State, Department of Physics, P.O. Box 339, Bloemfontein (South Africa)

    2014-09-15

    In the present work, red-emitting Ca{sub 2}V{sub 2}O{sub 7}:xEu{sup 3+} (x = 0.5-6.0 mol%) nanophosphors, in the form of powders, were synthesized by the citrate-gel combustion method using metal nitrates as precursors and citric acid as fuel. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy, photoluminescence (PL) and cathodoluminescence (CL) spectroscopy were used to study the structure, morphology and spectral properties of the samples. The chemical compositions and electronic states of the powders were analyzed with X-ray photoelectron spectroscopy. The average crystallite sizes estimated using the XRD data were found to be in the range of 30-45 nm, and were cross verified by TEM. The lattice parameters determined by the POWD program were approximated as a = 7.242 Aa, b = 6.674 Aa, c = 6.932 Aa and V = 291.24 Aa{sup 3}, respectively. Under UV (395 nm) (PL) and electron (CL) excitation, the nanophosphors show characteristic emission from the Eu{sup 3+} ion ({sup 5}D{sub 0} → {sup 7}F{sub j}, j = 1-5) with the main peaks at 612 and 616 nm. The maximum emission intensity was recorded from the sample with an Eu{sup 3+} concentration of 4 mol% and a critical energy distance of 19.084 Aa between the donor and the acceptor. Above this concentration, there was a reduction in the intensity due to dipole-dipole induced concentration quenching effects. The potential applications of this phosphor as a high color-purity phosphor in light-emitting diodes are evaluated. (orig.)

  16. IR Spectrum Data Bank System

    Institute of Scientific and Technical Information of China (English)

    Xie Dilin

    2004-01-01

    The infrared spectra of pure compounds of ninety thousands, poly compounds of twelve thousand, drugs of one thousand were included in the data bank. All of them can be searched out according to their serial number, chemical name, commercial name, amount of each atoms, or molecular formula, as well as their spectrum peak appearances. Program for spectrum information inputting, program for spectrum information search and program for spectrum peak appearance search were included in the system; in addition, spectrum information data bank, spectrum peak code data bank and spectrum figure data bank were attached to the system. System program was written by Visial Basic, and run under Windows system. The spectrum information data bank and spectrum figure data bank were administrated by Microsoft Access.The program for spectrum message inputting can be used to add message data and spectrum figure of some new compounds into the data banks by users themselves. The program for spectrum message search was designed to find out all the message data and spectrum figure of interested compound according to someone of the message data. The program for spectrum peak search was designed to find out some spectra most similar in peak shape with unknown spectrum by peak to peak comparison. When the wavenumbers and transmittances of main peaks in the spectrum of unknown sample were entered, the spectrum peak search was performed and several hits with higher similarity were reported including their similarity scores, spectrum serial numbers, sample's states,melt points, molecular formulas as well as spectrum images. If the search result was not satisfactory,some methods to modify spectrum parameters were reminded and search was performed again.

  17. The First Science Flight of the Faint Intergalactic medium Redshifted Emission Balloon (FIREBALL)

    Science.gov (United States)

    Martin, Christopher; Milliard, Bruno; Schiminovich, David; Tuttle, Sarah; Matuszewski, Matt; Rahman, Shahin; Evrard, Jean; Frank, Stephan; Deharveng, Jean-Michel; Peroux, Celine

    We have completed the second flight of the path-finding experiment, the Faint Intergalactic medium Redshifted Emission Balloon (FIREBALL), designed to discover and map faint emis-sion from the Intergalactic Medium (IGM). The second flight was fully successful, proving a fully functional fine pointing gondola with arcsec level capability, a 1 meter diameter (fixed) parabola primary telescope with planar sidereostat for pointing, a complete closed loop guide camera and control software, and a fiber fed UV integral field spectrograph feeding a spare GALEX Near UV detector. Three scientific targets were observed, and analysis of the data shows that the instrument performed as expected. The flux measurements obtained will be compared to models for IGM emission. We discuss future modifications to the payload that will achieve a 10-to 30-fold increase in sensitivity over science flight 1. We also discuss other instrument configurations that can utilize the 1-meter UV telescope and arcsecond pointing platform, and their corresponding science objectives. FIREBALL is a collaboration of NASA, Caltech, Columbia University, CNES, and Laboratorie Astrophysique Marseille, and is sup-ported by NASA, CNES, and CNRS.

  18. The character of biological tissue's SHG spectrum

    Science.gov (United States)

    Tian, Long; Guo, Zhouyi; Deng, Xiaoyuan; Zhai, Juan; Zhuang, Zhengfei

    2009-08-01

    In biological tissue, the relative strongly SHG (second-harmonic Generation) will be shown in the collagen and the cell membrane with dye molecules under the irradiation of laser. The SHG has a broad prospect in detecting and imaging of the biological tissue for its non-phototoxicity and non-photobleaching. In biological tissue, not only the SHG intensity and emission angle will have more obvious change, but also the spectrum of the SHG will be subject to certain changes when the temperature in the outside world and its structure got a obviously change. According to Kuzyk and Kruhlak's dipole-free sum-over-states theory which gives a introduction for the nonlinear susceptibilities, the relationship between hyperpolarizability of biological tissue, environment temperature and biological tissue's structure is shown in mathematics. In the conditions of control the temperature in experiments, the biological tissue's structure shift can be detected by analyze the SHG spectrum of biological. Also diverse biological tissues' differences in structure can be demonstrated in the spectrum. The change of SHG spectrum for the same biological tissue with environment temperature is discussed. Therefore, SHG spectroscopy analysis provides a new technology for the process of biological tissue lesions. Beside, this research gives a theory results provided by environment temperature which give an explanation for experiment result.

  19. A Novel Technique to Measure Gain Spectrum for Fabry-Pérot Semiconductor Lasers

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel gain measurement technique based on the integration of the measured amplified spontaneous emission spectrum multiplying a phase function over one longitudinal mode interval is proposed for Fabry-Perot semiconductor lasers.

  20. Estimation of Black Hole Masses from Steep Spectrum Radio Quasars

    Indian Academy of Sciences (India)

    Ye Chen; Zhi-Fu Chen; Yi-Ping Qin; You-Bing Li

    2011-03-01

    In this work, we employ a sample of 185 steep-spectrum radio quasars (SSRQs) to estimate their black hole masses from broad emission lines. Our black hole masses are compared with the virial black hole masses estimated by Shen (2010). We find that there is a large deviation between the two kinds of values if the black hole masses are estimated from broad emission line of CIV. However, both values are in agreement if the black hole masses are estimated from broad emission line of MgII or H.

  1. Sinclair ZX Spectrum.

    Science.gov (United States)

    Rodwell, Peter

    1982-01-01

    Describes and evaluates the hardware, software, peripheral devices, performance capabilities, and programing capacity of the Sinclair ZX Spectrum microcomputer. The computer's display system, its version of the BASIC programing language, its graphics capabilities, and the unique features of its data entry keyboard are discussed. (JL)

  2. Autism Spectrum Disorder (ASD)

    Science.gov (United States)

    ... with: 1 Communication and interaction with other people Restricted interests and repetitive behaviors Different people with autism can have different symptoms. For this reason, autism is known as a spectrum disorder —which means that there is a range of ...

  3. Autism Spectrum Disorder

    Centers for Disease Control (CDC) Podcasts

    2014-04-02

    This podcast discusses autism spectrum disorder (ASD), a developmental disability that causes problems with social, communication, and behavioral skills. CDC estimates that one in 68 children has been identified as having ASD.  Created: 4/2/2014 by National Center on Birth Defects and Developmental Disabilities (NCBDDD).   Date Released: 4/2/2014.

  4. What is a Spectrum?

    CERN Document Server

    Bolton, Adam S; Brownstein, Joel; Pandey, Parul; Schlegel, David; Shu, Yiping

    2011-01-01

    This contribution describes the "spectro-perfectionism" algorithm of Bolton & Schlegel (2010, PASP, 122, 248) that is being implemented within the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III (SDSS-III), in terms of its potential to deliver Poisson-limited sky subtraction and lossless compression of the input spectrum likelihood functional given raw CCD data.

  5. Battlefield spectrum management

    Science.gov (United States)

    Sivakumar, C.

    1997-06-01

    Modern tactical communications systems rely on radios to support network and user connectivity. One of the challenges for network planners and managers is to make best use of scarce and vulnerable frequency spectrum resources to support the communication needs of war fighters. With the wide variety of Iris radio types typically to be deployed in the battlefield (ranging from high frequency to super high frequency), a comprehensive suite of tools is necessary to ensure that frequency interference is kept minimum. Without a sophisticated frequency spectrum management system, the most advanced tactical communications systems could be rendered useless, jeopardizing human life and national security. For these reasons, it is important to develop an Iris wide battlefield spectrum management capability that takes full advantage of current frequency spectrum management research and development (R&D), related tools, and supporting technology for assigning frequencies. This session briefly describes various assignment strategies being adopted in the Iris BFSM for overcoming cosite/collocated/farsite interferences along with the propagation models [from high frequency (HF) to super high frequency (SHF)] used for the assignment of frequencies. Also a brief thread outlining the process for generating frequency allocation/assignment request and analysis of frequency interference is discussed.

  6. Spectrum emission considerations for baseband-modeled CALLUM architectures

    DEFF Research Database (Denmark)

    Strandberg, Roland; Andreani, Pietro; Sundström, Lars

    2005-01-01

    . Simulation examples are presented on how three different CALLUM architectures behave for enhanced data rates for global system for mobile communications evolution and wide-band code-division multiple-access signals. In addition, we have considered the effects of loop time delay, which is the ultimate...... of the control equations governing it. The main purpose of this paper has been the derivation of a linearized model for the control equations, which enables the use of linear network theory in the study of CALLUM. In particular, it can be used to analyze the stability and maximize the bandwidth of the system...

  7. Spectrum emission considerations for baseband-modeled CALLUM architectures

    DEFF Research Database (Denmark)

    Strandberg, Roland; Andreani, Pietro; Sundström, Lars

    2005-01-01

    . Simulation examples are presented on how three different CALLUM architectures behave for enhanced data rates for global system for mobile communications evolution and wide-band code-division multiple-access signals. In addition, we have considered the effects of loop time delay, which is the ultimate...

  8. Absorption spectrum, mass spectrometric properties, and electronic structure of 1,2-benzoquinone.

    Science.gov (United States)

    Albarran, Guadalupe; Boggess, William; Rassolov, Vitaly; Schuler, Robert H

    2010-07-22

    Absorption spectrophotometric and mass spectrometric properties of 1,2-benzoquinone, prepared in aqueous solution by the hexachloroiridate(IV) oxidation of catechol and isolated by HPLC, are reported. Its absorption spectrum has a broad moderately intense band in the near UV with an extinction coefficient of 1370 M(-1)cm(-1) at its 389 nm maximum. The oscillator strength of this band contrasts with those of the order-of-magnitude stronger approximately 250 nm bands of most 1,4-benzoquinones. Gaussian analysis of its absorption spectrum indicates that it also has modestly intense higher energy bands in the 250-320 nm region. In atmospheric pressure mass spectrometric studies 1,2-benzoquinone exhibits very strong positive and negative mass 109 signals that result from the addition of protons and hydride ions in APCI and ESI ion sources. It is suggested that the hydride adduct is formed as the result of the highly polar character of ortho-quinone. On energetic collision the hydride adduct loses an H atom to produce the 1,2-benzosemiquinone radical anion. The present studies also show that atmospheric pressure mass spectral patterns observed for catechol are dominated by signals of 1,2-benzoquinone resulting from oxidation of catechol in the ion sources. Computational studies of the electronic structures of 1,2-benzoquinone, its proton and hydride ion adducts, and 1,2-benzosemiquinone radical anion are reported. These computational studies show that the structures of the proton and hydride adducts are similar and indicate that the hydride adduct is the proton adduct of a doubly negatively charged 1,2-benzoquinone. The contrast between the properties of 1,2- and 1,4-benzoquinone provides the basis for considerations on the effects of conjugation in aromatic systems.

  9. Roper resonance and the baryon spectrum

    Science.gov (United States)

    Elsey, J. A.; Afnan, I. R.

    1989-10-01

    We present a method for calculating the baryon spectrum in the cloudy-bag model in which the masses of the baryons are identical to the poles of the S matrix in the complex energy plane. In particular, we demonstrate that the width for the decay of these resonances by pion emission is dependent on whether the calculations are carried out on the real energy axis or at the resonance poles, the latter being consistent with the scattering experiments that determine these widths. Results for N*(1440) are presented.

  10. Roper resonance and the baryon spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Elsey, J.A.; Afnan, I.R. (School of Physical Sciences, The Flinders University of South Australia, Bedford Park, South Australia 5042, Australia (AU))

    1989-10-01

    We present a method for calculating the baryon spectrum in the cloudy-bag model in which the masses of the baryons are identical to the poles of the {ital S} matrix in the complex energy plane. In particular, we demonstrate that the width for the decay of these resonances by pion emission is dependent on whether the calculations are carried out on the real energy axis or at the resonance poles, the latter being consistent with the scattering experiments that determine these widths. Results for {ital N}{sup *}(1440) are presented.

  11. Infrared diode laser studies of the products from the reaction CH2($\\tilde{X}$3B1) + O2 and from the near-UV photolysis of CH3NCS

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, Ramon Arturo [Univ. of California, Berkeley, CA (United States)

    1993-12-01

    Absolute yields of CO, CO2, and H2CO formed in reaction of triplet methylene ($\\tilde{X}$3B1 ≡CH2) with O2 were determined using a flash kinetic spectrometer. CH2 radicals were generated by excimer laser photolysis of ketene and product formation was monitored by time-resolved infrared diode laser absorption. Reaction was carried out in a static gas cell at room temperature at 1--25 torr. Measured product yields were CO, 0.34 ± 0.06; CO2, 0.40 ± 0.08 H2CO, 0.16 ± 0.04. Rate constants for production of CO and CO2 were equivalent to the published rate constant for removal of CH2. Indirect evidence indicated that yield of OH is 0.30 ± 0.05. Ultraviolet spectrum of methyl isothiocyanate (CH3NCS ≡ MITC) and quantum yield for dissociation into methyl isocyanide (CH3NC) and atomic sulfur at 308 nm, Φ 0.98 ± 0.24, were measured. MITC is widely used as a fumigant and readily enters the atmosphere during and after application. Results indicate that photodissociation by sunlight is an effective pathway for removal of MITC from atmosphere. A mechanism is proposed to account for the observed formation of methyl isocyanate (CH3NCO) as a secondary product in controlled laboratory studies.

  12. The Electromagnetic Spectrum of Neutron Stars

    CERN Document Server

    Baykal, Altan; Inam, Sitki C; Grebenev, Sergei

    2005-01-01

    Neutron stars hold a central place in astrophysics, not only because they are made up of the most extreme states of the condensed matter, but also because they are, along with white dwarfs and black holes, one of the stable configurations that stars reach at the end of stellar evolution. Neutron stars posses the highest rotation rates and strongest magnetic fields among all stars. They radiate prolifically, in high energy electromagnetic radiation and in the radio band. This book is devoted to the selected lectures presented in the 6th NATO-ASI series entitled "The Electromagnetic Spectrum of Neutron Stars" in Marmaris, Turkey, on 7-18 June 2004. This ASI is devoted to the spectral properties of neutron stars. Spectral observations of neutron stars help us to understand the magnetospheric emission processes of isolated radio pulsars and the emission processes of accreting neutron stars. This volume includes spectral information from the neutron stars in broadest sense, namely neutrino and gravitational radiat...

  13. A Solar Minimum Irradiance Spectrum for Wavelengths below 1200 Å

    Science.gov (United States)

    Warren, Harry P.

    2005-03-01

    NRLEUV represents an independent approach to modeling the Sun's EUV irradiance and its variability. Our model utilizes differential emission measure distributions derived from spatially and spectrally resolved solar observations, full-disk solar images, and a database of atomic physics parameters to calculate the solar EUV irradiance. In this paper we present a new solar minimum irradiance spectrum for wavelengths below 1200 Å. This spectrum is based on extensive observations of the quiet Sun taken with the CDS and SUMER spectrometers on the Solar and Heliospheric Observatory (SOHO) and the most recent version of the CHIANTI atomic physics database. In general, we find excellent agreement between this new irradiance spectrum and our previous quiet-Sun reference spectrum derived primarily from Harvard Skylab observations. Our analysis does show that the quiet-Sun emission measure above about 1 MK declines more rapidly than in our earlier emission measure distribution and that the intensities of the EUV free-bound continua at some wavelengths are somewhat smaller than indicated by the Harvard observations. Our new reference spectrum is also generally consistent with recent irradiance observations taken near solar minimum. There are, however, two areas of persistent disagreement. Our solar spectrum indicates that the irradiance measurements overestimate the contribution of the EUV free-bound continua at some wavelengths by as much as a factor of 10. Our model also cannot reproduce the observed irradiances at wavelengths below about 150 Å. Comparisons with spectrally resolved solar and stellar observations indicate that only a small fraction of the emission lines in the 60-120 Å wavelength range are accounted for in CHIANTI.

  14. Analytical Account for the Constant Magnetic Field Effect on the Undulator Radiation Spectrum

    Science.gov (United States)

    Zhukovsky, K. V.

    2013-11-01

    The effect of the constant magnetic field on the planar undulator radiation (UR) is studied. We employ generalized special functions to investigate the UR intensity and spectrum, calculate critical strength of the constant field, affecting the electron motion in undulators. The influence of the Earth magnetism on several real undulators' emission and spectrum is investigated.

  15. Spread spectrum image steganography.

    Science.gov (United States)

    Marvel, L M; Boncelet, C R; Retter, C T

    1999-01-01

    In this paper, we present a new method of digital steganography, entitled spread spectrum image steganography (SSIS). Steganography, which means "covered writing" in Greek, is the science of communicating in a hidden manner. Following a discussion of steganographic communication theory and review of existing techniques, the new method, SSIS, is introduced. This system hides and recovers a message of substantial length within digital imagery while maintaining the original image size and dynamic range. The hidden message can be recovered using appropriate keys without any knowledge of the original image. Image restoration, error-control coding, and techniques similar to spread spectrum are described, and the performance of the system is illustrated. A message embedded by this method can be in the form of text, imagery, or any other digital signal. Applications for such a data-hiding scheme include in-band captioning, covert communication, image tamperproofing, authentication, embedded control, and revision tracking.

  16. Raman spectrum of asphaltene

    KAUST Repository

    Abdallah, Wael A.

    2012-11-05

    Asphaltenes extracted from seven different crude oils representing different geological formations from around the globe were analyzed using the Raman spectroscopic technique. Each spectrum is fitted with four main peaks using the Gaussian function. On the basis of D1 and G bands of the Raman spectrum, asphaltene indicated an ordered structure with the presence of boundary defected edges. The average aromatic sheet size of the asphaltene molecules is estimated within the range of 1.52-1.88 nm, which represents approximately seven to eight aromatic fused rings. This estimation is based on the integrated intensity of D1 and G bands, as proposed by Tunistra and Koenig. The results here are in perfect agreement with so many other used techniques and indicate the potential applicability of Raman measurements to determine the average aromatic ring size and its boundary. © 2012 American Chemical Society.

  17. The Supersymmetric Particle Spectrum

    CERN Document Server

    Barger, V; Ohmann, P

    1994-01-01

    We examine the spectrum of supersymmetric particles predicted by grand unified theoretical (GUT) models where the electroweak symmetry breaking is accomplished radiatively. We evolve the soft supersymmetry breaking parameters according to the renormalization group equations (RGE). The minimization of the Higgs potential is conveniently described by means of tadpole diagrams. We present complete one-loop expressions for these minimization conditions, including contributions from the matter and the gauge sectors. We concentrate on the low $\\tan \\beta$ fixed point region (that provides a natural explanation of a large top quark mass) for which we find solutions to the RGE satisfying both experimental bounds and fine-tuning criteria. We also find that the constraint from the consideration of the lightest supersymmetric particle as the dark matter of the universe is accommodated in much of parameter space where the lightest neutralino is predominantly gaugino. The supersymmetric mass spectrum displays correlations...

  18. [Clinical spectrum of neuroborreliosis].

    Science.gov (United States)

    Owecki, Michał K; Kozubski, Wojciech

    2007-01-01

    Lyme disease is a multisystem infectious disease with a wide variety of symptoms involving the skin as well as nervous, musculosceletal and cardiovascular systems. Lyme disease is caused by spirochaete Borrelia burgdorferi transmitted by Ixodes tics in endemic regions. The diverse manifestations of neuroborreliosis require it to be included in differential diagnosis of many neurological disorders. The paper reviews the spectrum of clinical symptoms of nervous system involvement in early and late Lyme disease.

  19. AUTISM SPECTRUM DISORDERS (ASD)

    OpenAIRE

    Middha Akanksha; Kataria Sahil; Sandhu Premjeet; Kapoor Bhawna

    2011-01-01

    Autism or Autism Spectrum Disorders (ASD) is a serious neurological disorder affecting communication skills, social interactions, adaptability in an individual, and also causes dramatic changes in behavioral patterns. This condition typically lasts throughout one’s lifetime and affects both, children as well as adults. Research has shown a tenfold increase in autism cases over the past decade and still rising at an alarming pace. The origins of autism are not known even to modern science. Aut...

  20. Model-based x-ray energy spectrum estimation algorithm from CT scanning data with spectrum filter

    Science.gov (United States)

    Li, Lei; Wang, Lin-Yuan; Yan, Bin

    2016-10-01

    With the development of technology, the traditional X-ray CT can't meet the modern medical and industry needs for component distinguish and identification. This is due to the inconsistency of X-ray imaging system and reconstruction algorithm. In the current CT systems, X-ray spectrum produced by X-ray source is continuous in energy range determined by tube voltage and energy filter, and the attenuation coefficient of object is varied with the X-ray energy. So the distribution of X-ray energy spectrum plays an important role for beam-hardening correction, dual energy CT image reconstruction or dose calculation. However, due to high ill-condition and ill-posed feature of system equations of transmission measurement data, statistical fluctuations of X ray quantum and noise pollution, it is very hard to get stable and accurate spectrum estimation using existing methods. In this paper, a model-based X-ray energy spectrum estimation method from CT scanning data with energy spectrum filter is proposed. First, transmission measurement data were accurately acquired by CT scan and measurement using phantoms with different energy spectrum filter. Second, a physical meaningful X-ray tube spectrum model was established with weighted gaussian functions and priori information such as continuity of bremsstrahlung and specificity of characteristic emission and estimation information of average attenuation coefficient. The parameter in model was optimized to get the best estimation result for filtered spectrum. Finally, the original energy spectrum was reconstructed from filtered spectrum estimation with filter priori information. Experimental results demonstrate that the stability and accuracy of X ray energy spectrum estimation using the proposed method are improved significantly.

  1. Electric Current Induced Light Emission from C60

    NARCIS (Netherlands)

    Palstra, T.T.M.; Haddon, R.C.; Lyons, K.B.

    1997-01-01

    We report the luminescence of C60 crystals and films due to the passage of an electrical current. The current-voltage behavior is highly non-linear with light-emission beyond a threshold voltage. The emission spectrum is featureless and resembles black-body radiation with an effective temperature on

  2. Spectrum Services 2007

    Science.gov (United States)

    Dobos, L.; Budavári, T.; Csabai, I.; Szalay, A. S.

    2008-10-01

    We present the Filter and Spectrum Services consisting of easy-to-use web applications and web services for searching, plotting and managing large collections of spectral energy distribution data and filter profiles as well as for performing various scientific operations on spectra in a unified framework. The services provide keyword search, advanced query forms and SQL query possibilities for selecting spectra or bandpass curves which may be retrieved in a variety of file formats including XML, VOTable and ASCII. All SDSS DR1-DR5 spectra had been loaded into a database as well as the entire 2dF catalog that adds up to more than 2.5 million SEDs of about a million spatial objects, but registered users can upload their own data making it available for the rest of the community and are free to modify or delete them at any time. Theoretical catalogs, such as the Bruzual-Charlot stochastic burst model spectrum library (100k spectra) and the BaSeL stellar library are also available. Scientific services allow building rest-frame composite spectra out of selected spectra; calculating synthetic magnitudes by convolving spectra with an arbitrary set of bandpass curves of optical instrument filters to generate simulated photometric catalogs on-the-fly; galactic extinction correction, fitting of the continuum using different set of templates (Bruzual-Charlot '03 templates, SDSS eigenspectra), line fitting. All scientific functionalities are available from the web user interface and via the SOAP web services for programmers. MySpectrum is a cross-platform version of the spectrum web service for setting up your own spectrum repository. It integrates into the main service allowing easy access to your data for the whole VO community. The main idea behind our web services is to move scientific functionalities physically close to the database in order to spare network bandwidth. This way scientists may do research without setting up expensive hardware, downloading large datasets

  3. High flux lithium antineutrino source with variable hard spectrum

    CERN Document Server

    Lyashuk, V I

    2016-01-01

    The high flux antineutrino source with hard antineutrino spectrum based on neutron activation of 7Li and subsequent fast beta-decay (T 1/2 = 0.84 s) of the 8Li isotope with emission of antineutrino with energy up to 13 MeV - is discussed. Creation of the intensive isotope neutrino source of hard spectrum will allow to increase the detection statistics of neutrino interaction and it is especially urgent for oscillation experiments. The scheme of the proposed neutrino source is based on the continuous transport of the created 8Li to the neutrino detector, which moved away from the place of neutron activation. Analytical expressions for lithium antineutrino flux is obtained. The discussed source will ensure to increase the cross section for reactions with deuteron from several times to tens compare to the reactor antineutrino spectrum. An another unique feature of the installation is the possibility to vary smoothly the hardness of the antineutrino spectrum.

  4. Sharing a quota on cumulative carbon emissions

    Science.gov (United States)

    Raupach, Michael R.; Davis, Steven J.; Peters, Glen P.; Andrew, Robbie M.; Canadell, Josep G.; Ciais, Philippe; Friedlingstein, Pierre; Jotzo, Frank; van Vuuren, Detlef P.; Le Quéré, Corinne

    2014-10-01

    Any limit on future global warming is associated with a quota on cumulative global CO2 emissions. We translate this global carbon quota to regional and national scales, on a spectrum of sharing principles that extends from continuation of the present distribution of emissions to an equal per-capita distribution of cumulative emissions. A blend of these endpoints emerges as the most viable option. For a carbon quota consistent with a 2 °C warming limit (relative to pre-industrial levels), the necessary long-term mitigation rates are very challenging (typically over 5% per year), both because of strong limits on future emissions from the global carbon quota and also the likely short-term persistence in emissions growth in many regions.

  5. Hybrid spread spectrum radio system

    Science.gov (United States)

    Smith, Stephen F [London, TN; Dress, William B [Camas, WA

    2010-02-09

    Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.

  6. [Analyses of spectral emissivity in radiation temperature measurement].

    Science.gov (United States)

    Fu, Tai-Ran; Cheng, Xiao-Fang; Zhong, Mao-Hua; Yang, Zang-Jian

    2008-01-01

    The complexity of the spectral emissivity of actual surfaces is the key point in the research and applications of radiation temperature measurement, resulting in the difficulty in the achievement of the temperature measurement. In the present paper, based on the discussions of the Taylor expansion, the non-dimension wavelength and the exponent, the authors describe the mathematical expression of the spectral emissivity of actual surfaces, and establish the general spectral emissivity function. Through the fitting of experimental data of the spectral emissivities of different metals at different temperatures, the applicability of the spectral emissivity function is verified which especially becomes the fundamental in the research of primary spectrum pyrometry.

  7. Discrete quantum spectrum of black holes

    Energy Technology Data Exchange (ETDEWEB)

    Lochan, Kinjalk, E-mail: kinjalk@iucaa.in; Chakraborty, Sumanta, E-mail: sumanta@iucaa.in

    2016-04-10

    The quantum genesis of Hawking radiation is a long-standing puzzle in black hole physics. Semi-classically one can argue that the spectrum of radiation emitted by a black hole look very much sparse unlike what is expected from a thermal object. It was demonstrated through a simple quantum model that a quantum black hole will retain a discrete profile, at least in the weak energy regime. However, it was suggested that this discreteness might be an artifact of the simplicity of eigen-spectrum of the model considered. Different quantum theories can, in principle, give rise to different complicated spectra and make the radiation from black hole dense enough in transition lines, to make them look continuous in profile. We show that such a hope from a geometry-quantized black hole is not realized as long as large enough black holes are dubbed with a classical mass area relation in any gravity theory ranging from GR, Lanczos–Lovelock to f(R) gravity. We show that the smallest frequency of emission from black hole in any quantum description, is bounded from below, to be of the order of its inverse mass. That leaves the emission with only two possibilities. It can either be non-thermal, or it can be thermal only with the temperature being much larger than 1/M.

  8. Tritium diagnostics by Balmer-alpha emission

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, C.H.; Ramsey, A.T.; Johnson, D.W.; Diesso, M.

    1993-02-01

    Spectral line emission from tritium in a plasma may be distinguished from deuterium emission by a small isotope shift. A diagnostic system to measure tritium Balmer-alpha emission from the plasma edge has been installed on TFTR. This system has been used in deuterium plasmas, and the deuterium alpha line profile used as a basis to predict the spectrum at differing tritium concentrations in future D-T runs. The tritium and deuterium lines are partially blended, however, analysis of the predicted D-T spectra by a line fitting program produced estimates of the tritium density that closely matched those input to the spectra, providing confidence that the tritium density can be reliably measured. The spectrum maps the tritium velocity distribution at the plasma edge and will be important for studies of tritium edge physics.

  9. Hubble Space Telescope Studies of Nearby Type Ia Supernovae: The Mean Maximum Light Ultraviolet Spectrum and its Dispersion

    CERN Document Server

    Cooke, Jeff; Sullivan, Mark; Nugent, Peter; Howell, D Andrew; Gal-Yam, Avishay; Lidman, Chris; Bloom, Joshua S; Cenko, S Bradley; Kasliwal, Mansi M; Kulkarni, Shrinivas R; Law, Nicholas M; Ofek, Eran O; Quimby, Robert M

    2010-01-01

    We present the first results of an ongoing campaign using the STIS spectrograph on-board the Hubble Space Telescope (HST) whose primary goal is the study of near ultraviolet (UV) spectra of local Type Ia supernovae (SNe Ia). Using events identified by the Palomar Transient Factory and subsequently verified by ground-based spectroscopy, we demonstrate the ability to locate and classify SNe Ia as early as 16 days prior to maximum light. This enables us to trigger HST in a non-disruptive mode to obtain near UV spectra within a few days of maximum light for comparison with earlier equivalent ground-based spectroscopic campaigns conducted at intermediate redshifts, z ~ 0.5. We analyze the spectra of 12 Type Ia supernovae located in the Hubble flow with 0.01 < z < 0.08. Although a fraction of our eventual sample, these data, together with archival data, already provide a substantial advance over that previously available. Restricting samples to those of similar phase and stretch, the mean UV spectrum agrees r...

  10. Oxygen-independent inactivation of Haemophilus influenzae transforming DNA by monochromatic radiation: action spectrum, effect of histidine and repair

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera-Juarez, E.; Setlow, J.K.; Swenson, P.A.; Peak, M.J.

    1976-01-01

    The action spectrum for the oxygen-independent inactivation of native transforming DNA from Haemophilus influenzae with near-uv radiation revealed a shoulder beginning at 334 and extending to 460 nm. The presence of 0.2 M histidine during irradiation produced a small increase in inactivation at 254, 290 and 313 nm, a large increase at 334 nm and a decrease in inactivation at 365, 405, and 460 nm. Photoreactivation did not reverse the DNA damage produced at pH 7.0 at 334, 365, 405 and 460 nm, but did reactivate the DNA after irradiation at 254, 290 and 313 nm. The inactivation of DNA irradiated at 254, 290 and 313 nm was considerably greater when the transforming ability was assayed in an excision-defective mutant compared with the wild type, although DNA irradiated at 334, 365, 405 and 460 nm showed smaller differences. These results suggest that the oxygen-independent inactivation of H. influenzae DNA at pH 7 by irradiation at 334, 365, 405 and 460 nm is caused by lesions other than pyrimidine dimers.

  11. Supernovae anisotropy power spectrum

    CERN Document Server

    Ghodsi, Hoda; Habibi, Farhang

    2016-01-01

    We contribute another anisotropy study to this field of research using Supernovae Type Ia (SNe Ia). In this work, we utilise the power spectrum calculation method and apply it to both the current SNe Ia data and simulation. Our simulations are constructed with the characteristics of the upcoming survey of the Large Synoptic Survey Telescope (LSST), which shall bring us the largest SNe Ia collection to date. We make predictions for the amplitude of a possible dipole anisotropy or anisotropy in higher multipole moments that would be detectable by the LSST.

  12. Hyperspectrally-Resolved Surface Emissivity Derived Under Optically Thin Clouds

    Science.gov (United States)

    Zhou, Daniel K.; Larar, Allen M.; Liu, Xu; Smith, William L.; Strow, L. Larrabee; Yang, Ping

    2010-01-01

    Surface spectral emissivity derived from current and future satellites can and will reveal critical information about the Earth s ecosystem and land surface type properties, which can be utilized as a means of long-term monitoring of global environment and climate change. Hyperspectrally-resolved surface emissivities are derived with an algorithm utilizes a combined fast radiative transfer model (RTM) with a molecular RTM and a cloud RTM accounting for both atmospheric absorption and cloud absorption/scattering. Clouds are automatically detected and cloud microphysical parameters are retrieved; and emissivity is retrieved under clear and optically thin cloud conditions. This technique separates surface emissivity from skin temperature by representing the emissivity spectrum with eigenvectors derived from a laboratory measured emissivity database; in other words, using the constraint as a means for the emissivity to vary smoothly across atmospheric absorption lines. Here we present the emissivity derived under optically thin clouds in comparison with that under clear conditions.

  13. The near-to-mid infrared spectrum of quasars

    CERN Document Server

    Hernán-Caballero, Antonio; Alonso-Herrero, Almudena; Mateos, Silvia

    2016-01-01

    We analyse a sample of 85 luminous L3um > 10^45.5 erg/s quasars with restframe ~2-11um spectroscopy from AKARI and Spitzer. Their high luminosity allows a direct determination of the near-infrared quasar spectrum free from host galaxy emission. A semi-empirical model consisting of a single template for the accretion disk and two blackbodies for the dust emission successfully reproduces the 0.1-10um spectral energy distributions (SEDs). Excess emission at 1-2um over the best-fitting model suggests that hotter dust is necessary in addition to the ~1200K blackbody and the disk to reproduce the entire near-infrared spectrum. Variation in the extinction affecting the disk and in the relative strength of the disk and dust components accounts for the diversity of individual SEDs. Quasars with higher dust-to-disk luminosity ratios show slightly redder infrared continua and less prominent silicate emission. We find no luminosity dependence in the shape of the average infrared quasar spectrum. The equivalent width of P...

  14. The Spitzer-IRS spectrum of SMP LMC 11

    CERN Document Server

    Bernard-Salas, J; Sloan, G C; Cami, J; Guiles, S; Houck, J R

    2006-01-01

    We present the first mid-infrared spectra of SMP LMC 11 in the Large Magellanic Cloud. While this object resembles a planetary nebula in the optical, its infrared properties are more similar to an object in transition from the asymptotic giant branch to the planetary nebula phase. A warm dust continuum dominates the infrared spectrum. The peak emission corresponds to a mean dust temperature of 330 K. The spectrum shows overlapping molecular absorption bands from 12 to 17 um corresponding to acetylene and polyacetylenic chains and benzene. This is the first detection of C4H2, C6H2, C6H6 and other molecules in an extragalactic object. The infrared spectrum of SMP LMC 11 is similar in many ways to that of the pre-planetary nebula AFGL 618. The IRS spectrum shows little evidence of nitrogen-based molecules which are commonly seen in Galactic AGB stars. Polycyclic aromatic hydrocarbons are also absent from the spectrum. The detection of the [NeII] 12.8 um line in the infrared and other forbidden emission lines in ...

  15. Extremely narrow spectrum of GRB110920A: further evidence for localised, subphotospheric dissipation

    CERN Document Server

    Iyyani, S; Ahlgren, B; Burgess, J M; Larsson, J; Pe'er, A; Lundman, C; Axelsson, M; McGlynn, S

    2015-01-01

    Much evidence points towards that the photosphere in the relativistic outflow in GRBs plays an important role in shaping the observed MeV spectrum. However, it is unclear whether the spectrum is fully produced by the photosphere or whether a substantial part of the spectrum is added by processes far above the photosphere. Here we make a detailed study of the $\\gamma-$ray emission from single pulse GRB110920A which has a spectrum that becomes extremely narrow towards the end of the burst. We show that the emission can be interpreted as Comptonisation of thermal photons by cold electrons in an unmagnetised outflow at an optical depth of $\\tau \\sim 20$. The electrons receive their energy by a local dissipation occurring close to the saturation radius. The main spectral component of GRB110920A and its evolution is thus, in this interpretation, fully explained by the emission from the photosphere including localised dissipation at high optical depths.

  16. Autistic spectrum disorders.

    Science.gov (United States)

    Singhania, Rajeshree

    2005-04-01

    Autistic spectrum disorders is a complex developmental disorder with social and communication dysfunction at its core. It has a wide clinical spectrum with a common triad of impairments -- social communication, social interaction and social imagination. Even mild or subtle difficulties can have a profound and devastating impact on the child. To be able to provide suitable treatments and interventions the distinctive way of thinking and learning of autistic children has to be understood. The core areas of social, emotional, communication and language deficits have to be addressed at all levels of functioning. The important goals of assessment include a categorical diagnosis of autism that looks at differential diagnosis, a refined precise documentation of the child's functioning in various developmental domains and ascertaining presence of co-morbid conditions. The interventions have to be adapted to the individual's chronological age, developmental phase and level of functioning. The strategies of curriculum delivery and teaching the child with autism is distinctive and includes presence of structure to increase predictability and strategies to reduce arousal of anxiety.

  17. Transverse myelitis spectrum disorders

    Directory of Open Access Journals (Sweden)

    Pandit Lekha

    2009-01-01

    Full Text Available Acute transverse myelitis (ATM is an inflammatory demyelinating disorder that affects the spinal cord focally resulting in motor sensory and autonomic dysfunction. Establishing the diagnosis of ATM is not as difficult as determining the possible etiology. There is a difference in the perception of ATM seen in the West as compared to developing countries. In the West multiple sclerosis (MS is the most common inflammatory disorder of the central nervous system. An attack of ATM may be the beginning of MS. However, this may not be the case in developing countries where MS is uncommon. Most often transverse myelitis is monophasic and at best represents a site-restricted form of acute disseminated encephalomyelitis (ADEM. Traditionally the combination of optic neuritis and ATM, occurring as a monophasic illness would have been called as neuromyelitis optica (NMO. Changing concepts in the definition of NMO and the discovery of a biomarker, neuromyelitis optica immunoglobulin (NMO_IgG, has changed the way relapsing autoimmune disorders are being perceived currently. A variety of idiopathic inflammatory disorders such as Japanese form of optic spinal MS, recurrent myelitis, and recurrent optic neuritis have been brought under the umbrella of neuromyelitis spectrum disorders because of the association with NMO-IgG. Complete transverse myelitis accompanied by longitudinally extensive transverse myelitis which is seronegative for this biomarker has also been reported from several countries including Japan, Australia, and India. Thus, ATM is a heterogeneous disorder with a varied clinical spectrum, etiology, and outcome.

  18. A LIGHT CURVE ANALYSIS OF CLASSICAL NOVAE: FREE-FREE EMISSION VERSUS PHOTOSPHERIC EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Hachisu, Izumi [Department of Earth Science and Astronomy, College of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902 (Japan); Kato, Mariko, E-mail: hachisu@ea.c.u-tokyo.ac.jp, E-mail: mariko@educ.cc.keio.ac.jp [Department of Astronomy, Keio University, Hiyoshi, Kouhoku-ku, Yokohama 223-8521 (Japan)

    2015-01-10

    We analyzed light curves of seven relatively slower novae, PW Vul, V705 Cas, GQ Mus, RR Pic, V5558 Sgr, HR Del, and V723 Cas, based on an optically thick wind theory of nova outbursts. For fast novae, free-free emission dominates the spectrum in optical bands rather than photospheric emission, and nova optical light curves follow the universal decline law. Faster novae blow stronger winds with larger mass-loss rates. Because the brightness of free-free emission depends directly on the wind mass-loss rate, faster novae show brighter optical maxima. In slower novae, however, we must take into account photospheric emission because of their lower wind mass-loss rates. We calculated three model light curves of free-free emission, photospheric emission, and their sum for various white dwarf (WD) masses with various chemical compositions of their envelopes and fitted reasonably with observational data of optical, near-IR (NIR), and UV bands. From light curve fittings of the seven novae, we estimated their absolute magnitudes, distances, and WD masses. In PW Vul and V705 Cas, free-free emission still dominates the spectrum in the optical and NIR bands. In the very slow novae, RR Pic, V5558 Sgr, HR Del, and V723 Cas, photospheric emission dominates the spectrum rather than free-free emission, which makes a deviation from the universal decline law. We have confirmed that the absolute brightnesses of our model light curves are consistent with the distance moduli of four classical novae with known distances (GK Per, V603 Aql, RR Pic, and DQ Her). We also discussed the reason why the very slow novae are about ∼1 mag brighter than the proposed maximum magnitude versus rate of decline relation.

  19. Integrated Emissivity And Temperature Measurement

    Science.gov (United States)

    Poulsen, Peter

    2005-11-08

    A multi-channel spectrometer and a light source are used to measure both the emitted and the reflected light from a surface which is at an elevated temperature relative to its environment. In a first method, the temperature of the surface and emissivity in each wavelength is calculated from a knowledge of the spectrum and the measurement of the incident and reflected light. In the second method, the reflected light is measured from a reference surface having a known reflectivity and the same geometry as the surface of interest and the emitted and the reflected light are measured for the surface of interest. These measurements permit the computation of the emissivity in each channel of the spectrometer and the temperature of the surface of interest.

  20. Possible effect of subsurface inhomogeneities on the lunar microwave spectrum

    Science.gov (United States)

    Fisher, A. D.; Staelin, D. H.

    1977-01-01

    Inhomogeneities beneath the lunar surface could alter the average microwave emission spectrum of the moon in a fashion generally consistent with observations, even in the absence of an average heat flux or density gradients with depth. The lunar subsurface was modeled as an inhomogeneous lossy dielectric with three-dimensional refractive-index fluctuations characterized by independent horizontal and vertical correlation lengths. The model suggests that attempts to infer the physical properties of the moon from the lunar microwave spectrum could be significantly inaccurate if subsurface scattering were neglected.

  1. On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main sequence stars

    CERN Document Server

    Mendigutía, I; Rigliaco, E; Fairlamb, J R; Calvet, N; Muzerolle, J; Cunningham, N; Lumsden, S L

    2015-01-01

    Correlations between the accretion luminosity and emission line luminosities (L_acc and L_line) of pre-main sequence (PMS) stars have been published for many different spectral lines, which are used to estimate accretion rates. Despite the origin of those correlations is unknown, this could be attributed to direct or indirect physical relations between the emission line formation and the accretion mechanism. This work shows that all (near-UV/optical/near-IR) L_acc-L_line correlations are the result of the fact that the accretion luminosity and the stellar luminosity (L_star) are correlated, and are not necessarily related with the physical origin of the line. Synthetic and observational data are used to illustrate how the L_acc-L_line correlations depend on the L_acc-L_star relationship. We conclude that because PMS stars show the L_acc-L_star correlation immediately implies that L_acc also correlates with the luminosity of all emission lines, for which the L_acc-L_line correlations alone do not prove any phy...

  2. AURORA on MEGSAT 1 a photon counting observatory for the Earth UV night-sky background and Aurora emission

    CERN Document Server

    Monfardini, A; Stalio, R; Mahne, N; Battiston, R; Menichelli, M; Mazzinghi, P

    2001-01-01

    A low-mass, low-cost photon-counting scientific payload has been developed and launched on a commercial microsatellite in order to study the near-UV night-sky background emission with a telescope nicknamed 'Notte' and the Aurora emission with 'Alba'. AURORA, this is the name of the experiment, will determine, with the 'Notte' channel, the overall night-side photon background in the 300-400 nm spectral range, together with a particular 2 sup + N sub 2 line (lambda sub c =337 nm). The 'Alba' channel, on the other hand, will study the Aurora emissions in four different spectral bands (FWHM=8.4-9.6 nm) centered on: 367 nm (continuum evaluation), 391 nm (1 sup - N sup + sub 2), 535 nm (continuum evaluation), 560 nm (OI). The instrument has been launched on the 26 September, 2000 from the Baikonur cosmodrome on a modified SS18 Dnepr-1 'Satan' rocket. The satellite orbit is nearly circular (h sub a sub p sub o sub g sub e sub e =648 km, e=0.0022), and the inclination of the orbital plane is 64.56 deg. An overview of...

  3. Quantum corrected non-thermal radiation spectrum from the tunnelling mechanism

    CERN Document Server

    Chakraborty, Subenoy; Corda, Christian

    2015-01-01

    Tunnelling mechanism is today considered a popular and widely used method in describing Hawking radiation. However, in relation to black hole (BH) emission, this mechanism is mostly used to obtain the Hawking temperature by comparing the probability of emission of an outgoing particle with the Boltzmann factor. On the other hand, Banerjee and Majhi reformulated the tunnelling framework deriving a black body spectrum through the density matrix for the outgoing modes for both the Bose-Einstein distribution and the Fermi-Dirac distribution. In contrast, Parikh and Wilczek introduced a correction term performing an exact calculation of the action for a tunnelling spherically symmetric particle and, as a result, the probability of emission of an outgoing particle corresponds to a non-strictly thermal radiation spectrum. Recently, one of us (C. Corda) introduced a BH effective state and was able to obtain a non-strictly black body spectrum from the tunnelling mechanism corresponding to the probability of emission o...

  4. A Cognitive Agent for Spectrum Monitoring and Informed Spectrum Access

    Science.gov (United States)

    2017-06-01

    ARL-TR-8041 ● JUNE 2017 US Army Research Laboratory A Cognitive Agent for Spectrum Monitoring and Informed Spectrum Access by...needed. Do not return it to the originator. ARL-TR-8041 ● JUNE 2017 US Army Research Laboratory A Cognitive Agent for Spectrum...should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of

  5. Rotational spectrum of tryptophan

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, M. Eugenia, E-mail: maria.sanz@kcl.ac.uk; Cabezas, Carlos, E-mail: ccabezas@qf.uva.es; Mata, Santiago, E-mail: santiago.mata@uva.es; Alonso, Josè L., E-mail: jlalonso@qf.uva.es [Grupo de Espectroscopia Molecular (GEM), Edificio Quifima, Laboratorios de Espectroscopia y Bioespectroscopia, Unidad Asociada CSIC, Parque Científico Uva, Universidad de Valladolid, 47011 Valladolid (Spain)

    2014-05-28

    The rotational spectrum of the natural amino acid tryptophan has been observed for the first time using a combination of laser ablation, molecular beams, and Fourier transform microwave spectroscopy. Independent analysis of the rotational spectra of individual conformers has conducted to a definitive identification of two different conformers of tryptophan, with one of the observed conformers never reported before. The analysis of the {sup 14}N nuclear quadrupole coupling constants is of particular significance since it allows discrimination between structures, thus providing structural information on the orientation of the amino group. Both observed conformers are stabilized by an O–H···N hydrogen bond in the side chain and a N–H···π interaction forming a chain that reinforce the strength of hydrogen bonds through cooperative effects.

  6. Rotational Spectrum of Tryptophan

    Science.gov (United States)

    Sanz, M. Eugenia; Cabezas, Carlos; Mata, Santiago; Alonso, José L.

    2014-06-01

    The rotational spectrum of the natural amino acid tryptophan has been observed using a recently constructed LA-MB-FTMW spectrometer, specifically designed to optimize the detection of heavier molecules at a lower frequency range. Independent analyses of the rotational spectra of individual conformers have conducted to a definitive identification of two different conformers of tryptophan, with one of the observed conformers never reported before. The experimental values of the 14N nuclear quadrupole coupling constants have been found capital in the discrimination of the conformers. Both observed conformers are stabilized by a O-H\\cdotsN hydrogen bond in the side chain and a N-H\\cdotsπ interaction forming a chain that reinforces the strength of hydrogen bonds through cooperative effects.

  7. Autism Spectrum Disorders

    Directory of Open Access Journals (Sweden)

    Rebecca E. Rosenberg

    2011-01-01

    Full Text Available We used a national online registry to examine variation in cumulative prevalence of community diagnosis of psychiatric comorbidity in 4343 children with autism spectrum disorders (ASD. Adjusted multivariate logistic regression models compared influence of individual, family, and geographic factors on cumulative prevalence of parent-reported anxiety disorder, depression, bipolar disorder, and attention deficit/hyperactivity disorder or attention deficit disorder. Adjusted odds of community-assigned lifetime psychiatric comorbidity were significantly higher with each additional year of life, with increasing autism severity, and with Asperger syndrome and pervasive developmental disorder—not otherwise specified compared with autistic disorder. Overall, in this largest study of parent-reported community diagnoses of psychiatric comorbidity, gender, autistic regression, autism severity, and type of ASD all emerged as significant factors correlating with cumulative prevalence. These findings could suggest both underlying trends in actual comorbidity as well as variation in community interpretation and application of comorbid diagnoses in ASD.

  8. Electromagnetic spectrum management system

    Science.gov (United States)

    Seastrand, Douglas R.

    2017-01-31

    A system for transmitting a wireless countermeasure signal to disrupt third party communications is disclosed that include an antenna configured to receive wireless signals and transmit wireless counter measure signals such that the wireless countermeasure signals are responsive to the received wireless signals. A receiver processes the received wireless signals to create processed received signal data while a spectrum control module subtracts known source signal data from the processed received signal data to generate unknown source signal data. The unknown source signal data is based on unknown wireless signals, such as enemy signals. A transmitter is configured to process the unknown source signal data to create countermeasure signals and transmit a wireless countermeasure signal over the first antenna or a second antenna to thereby interfere with the unknown wireless signals.

  9. Microwave Spectrum of Hexafluoroisopropanol

    Science.gov (United States)

    Shahi, Abhishek; Mani, Devendra; Arunan, E.

    2012-06-01

    Hexafluoroisopropanol (HFIP) is an important organic solvent and probably the only solvent which can dissolve polythene. IR studies, on this molecule confirm the existence of antiperiplanar (ap) and synclinical (sc) conformers. We have observed pure rotational spectrum of this molecule and the fitted rotational constants (A= 2105.1208(11) MHz, B= 1053.9942(3) MHz, C= 932.3398(3) MHz) confirm the presence of ap conformer. There are many other observed lines which most probably corresponds to sc structure and due to the large amplitude motion of H-atom, some of these transitions show tunneling splitting. Work is in progress for the deuterated (OD) and C-13 isotopologues of the monomer. HFIP is expected to exhibit interesting hydrogen bonding properties and we are planning to investigate them by studying its complex with water. The results will be presented in this talk. H. Schaal, T. Höber, and M. A. Suhm, J. Phys. Chem. A 104, 265 (2000).

  10. EVN observations of low-luminosity flat-spectrum AGNs

    CERN Document Server

    Caccianiga, A; Thean, A; Dennett-Thorpe, J

    2001-01-01

    We present and discuss the results of VLBI (EVN) observations of three low-luminosity (P(5 GHz)<10^25 W/Hz) Broad Emission Line AGNs carefully selected from a sample of flat spectrum radio sources (CLASS). Based on the total and the extended radio power at 5 GHz and at 1.4 GHz respectively, these objects should be technically classified as radio-quiet AGN and thus the origin of their radio emission is not clearly understood. The VLBI observations presented in this paper have revealed compact radio cores which imply a lower limit on the brightness temperature of about 3X10^8 K. This result rules out a thermal origin for the radio emission and strongly suggests an emission mechanism similar to that observed in more powerful radio-loud AGNs. Since, by definition, the three objects show a flat (or inverted) radio spectrum between 1.4 GHz and 8.4 GHz, the observed radio emission could be relativistically beamed. Multi-epoch VLBI observations can confirm this possibility in two years time.

  11. Stoppage in Autism Spectrum Disorders

    DEFF Research Database (Denmark)

    Grønborg, Therese Koops; Hansen, Stefan Nygaard; Nielsen, Svend V

    2015-01-01

    of bias in sibling recurrence risk estimation. This study investigated whether stoppage occurs in Danish families with a firstborn child diagnosed with autism spectrum disorders, and if stoppage was differential. We found that stoppage occurs moderately in Danish families affected by autism spectrum...... disorders, and that stoppage is differential. However, differential stoppage is a minor source of estimation bias in Danish sibling recurrence risk studies of autism spectrum disorders....

  12. CsI(Tl) infrared scintillation light yield and spectrum

    CERN Document Server

    Belogurov, S; Carugno, Giovanni; Conti, E; Iannuzzi, D; Meneguzzo, Anna Teresa

    2000-01-01

    Infrared emission from CsI(Tl) excited by approx 70 keV electrons was detected with an InGaAs PIN photodiode. Some parameters of infrared scintillation were studied. The emission spectrum is located between 1.55 and 1.70 mu m with a maximum at 1.60 mu m. The light yield of infrared scintillation is (4.9+-0.3)x10 sup 3 photons/MeV. Infrared scintillation caused by 3 MeV alpha-particles is detected as well.

  13. Characterization of multiphoton emission from aggregated gold nano particles

    Science.gov (United States)

    Eguchi, Akira; Lu, Phat; Kim, Youngsik; Milster, Tom D.

    2016-09-01

    Although gold nanoparticles (GNPs) are promising probes for biological imaging because of their attracting optical properties and bio-friendly nature, properties of the multi-photon (MP) emission from GNP aggregates produced by a short-wave infrared (SWIR) laser have not been examined. In this paper, characterization of MP emission from aggregated 50 nm GNPs excited by a femtosecond (fs) laser at 1560 nm is discussed with respect to aggregate structures. The key technique in this work is single particle spectroscopy. A pattern matching technique is applied to correlate MP emission and SEM images, which includes an optimization processes to maximize cross correlation coefficients between a binary microscope image and a binary SEM image with respect to xy displacement, image rotation angle, and image magnification. Once optimization is completed, emission spots are matched to the SEM image, which clarifies GNP ordering and emission properties of each aggregate. Correlation results showed that GNP aggregates have stronger MP emission than single GNPs. By combining the pattern matching technique with spectroscopy, MP emission spectrum is characterized for each GNP aggregate. A broad spectrum in the visible region and near infrared (NIR) region is obtained from GNP dimers, unlike previously reported surface plasmon enhanced emission spectrum.

  14. Regression in autistic spectrum disorders.

    Science.gov (United States)

    Stefanatos, Gerry A

    2008-12-01

    A significant proportion of children diagnosed with Autistic Spectrum Disorder experience a developmental regression characterized by a loss of previously-acquired skills. This may involve a loss of speech or social responsitivity, but often entails both. This paper critically reviews the phenomena of regression in autistic spectrum disorders, highlighting the characteristics of regression, age of onset, temporal course, and long-term outcome. Important considerations for diagnosis are discussed and multiple etiological factors currently hypothesized to underlie the phenomenon are reviewed. It is argued that regressive autistic spectrum disorders can be conceptualized on a spectrum with other regressive disorders that may share common pathophysiological features. The implications of this viewpoint are discussed.

  15. C iii] Emission in Star-forming Galaxies at z ∼ 1

    Science.gov (United States)

    Du, Xinnan; Shapley, Alice E.; Martin, Crystal L.; Coil, Alison L.

    2017-03-01

    The C iii]λλ1907, 1909 rest-frame UV emission doublet has recently been detected in galaxies during the epoch of reionization (z > 6), with a high equivalent width (EW; 10 Å, rest frame). Currently, it is possible to obtain much more detailed information for star-forming galaxies at significantly lower redshift. Accordingly, studies of their far-UV spectra are useful for understanding the factors modulating the strength of C iii] emission. We present the first statistical sample of C iii] emission measurements in star-forming galaxies at z ∼ 1. Our sample is drawn from the DEEP2 survey and spans the redshifts 0.64 ≤slant z ≤slant 1.35 ( =1.08). We find that the median EW of individual C iii] detections in our sample (1.30 Å) is much smaller than the typical value observed thus far at z > 6. Furthermore, out of 184 galaxies with coverage of C iii], only 40 have significant detections. Galaxies with individual C iii] detections have bluer colors and lower luminosities on average than those without, implying that strong C iii] emitters are in general young and low-mass galaxies without significant dust extinction. Using stacked spectra, we further investigate how C iii] strength correlates with multiple galaxy properties (M B , U ‑ B, M *, star formation rate, specific star formation rate) and rest-frame near-UV (Fe ii* and Mg ii) and optical ([O iii] and Hβ) emission line strengths. These results provide a detailed picture of the physical environment in star-forming galaxies at z ∼ 1, and motivate future observations of strong C iii] emitters at similar redshifts.

  16. Fundamental molecules of life are pigments which arose and co-evolved as a response to the thermodynamic imperative of dissipating the prevailing solar spectrum

    Science.gov (United States)

    Michaelian, K.; Simeonov, A.

    2015-08-01

    The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of today, oxygen and ozone derived from life processes are performing the short-wavelength UV-C and UV-B dissipation. On Earth's surface, water and organic pigments in water facilitate the near-UV and visible photon dissipation. The first organic pigments probably formed, absorbed, and dissipated at those photochemically active wavelengths in the UV-C and UV-B that could have reached Earth's surface during the Archean. Proliferation of these pigments can be understood as an autocatalytic photochemical process obeying non-equilibrium thermodynamic directives related to increasing solar photon dissipation rate. Under these directives, organic pigments would have evolved over time to increase the global photon dissipation rate by (1) increasing the ratio of their effective photon cross sections to their physical size, (2) decreasing their electronic excited state lifetimes, (3) quenching radiative de-excitation channels (e.g., fluorescence), (4) covering ever more completely the prevailing solar spectrum, and (5) proliferating and dispersing to cover an ever greater surface area of Earth. From knowledge of the evolution of the spectrum of G-type stars, and considering the most probable history of the transparency of Earth's atmosphere, we construct the most probable Earth surface solar spectrum as a function of time and compare this with the history of molecular absorption maxima obtained from the available data in the literature. This comparison supports the conjecture that many fundamental molecules of life are pigments which arose, proliferated, and co-evolved as a response to dissipating the solar spectrum, supports the thermodynamic dissipation theory for the origin of life, constrains models for Earth's early atmosphere, and sheds

  17. Spectrum handoff algorithm with imperfect spectrum sensing incognitive radio networks

    Science.gov (United States)

    Ma, Bin; Bao, Xiao-min; Xie, Xian-zhong

    2016-10-01

    To guarantee the quality of service of licensed users, the unlicensed users must vacate the occupied channel by spectrum handoff if licensed users appear in the licensed spectrum. However, spectrum sensing with false alarm and missed detection may lead to more inaccuracy problems when unlicensed users perform spectrum handoff. To improve the problems mentioned before, we utilize PRP M/G/1 queuing network model to propose a spectrum handoff algorithm with error data retransmission mechanism and analyze its performance by transmission delay and extended data delivery time. In addition, we discuss the relationship between false alarm probability, extended data delivery time and user traffic load and verify the effectiveness of the proposed algorithm.

  18. PKA spectrum file

    Energy Technology Data Exchange (ETDEWEB)

    Kawai, M. [Toshiba Corp., Kawasaki, Kanagawa (Japan). Nuclear Engineering Lab.

    1997-03-01

    In the Japanese Nuclear Data Committee, the PKA/KERMA file containing PKA spectra, KERMA factors and DPA cross sections in the energy range between 10{sup -5} eV and 50 MeV is being prepared from the evaluated nuclear data. The processing code ESPERANT was developed to calculate quantities of PKA, KERMA and DPA from evaluated nuclear data for medium and heavy elements by using the effective single particle emission approximation (ESPEA). For light elements, the PKA spectra are evaluated by the SCINFUL/DDX and EXIFON codes, simultaneously with other neutron cross sections. The DPA cross sections due to charged particle emitted from light elements are evaluated for high neutron energy above 20 MeV. (author)

  19. Black hole quantum spectrum

    Science.gov (United States)

    Corda, Christian

    2013-12-01

    Introducing a black hole (BH) effective temperature, which takes into account both the non-strictly thermal character of Hawking radiation and the countable behavior of emissions of subsequent Hawking quanta, we recently re-analysed BH quasi-normal modes (QNMs) and interpreted them naturally in terms of quantum levels. In this work we improve such an analysis removing some approximations that have been implicitly used in our previous works and obtaining the corrected expressions for the formulas of the horizon's area quantization and the number of quanta of area and hence also for Bekenstein-Hawking entropy, its subleading corrections and the number of micro-states, i.e. quantities which are fundamental to realize the underlying quantum gravity theory, like functions of the QNMs quantum "overtone" number n and, in turn, of the BH quantum excited level. An approximation concerning the maximum value of n is also corrected. On the other hand, our previous results were strictly corrected only for scalar and gravitational perturbations. Here we show that the discussion holds also for vector perturbations. The analysis is totally consistent with the general conviction that BHs result in highly excited states representing both the "hydrogen atom" and the "quasi-thermal emission" in quantum gravity. Our BH model is somewhat similar to the semi-classical Bohr's model of the structure of a hydrogen atom. The thermal approximation of previous results in the literature is consistent with the results in this paper. In principle, such results could also have important implications for the BH information paradox.

  20. Identification of OSSO as a near-UV absorber in the Venusian atmosphere

    DEFF Research Database (Denmark)

    Frandsen, Benjamin Normann; Wennberg, Paul O.; Kjærgaard, Henrik Grum

    2016-01-01

    The planet Venus exhibits atmospheric absorption in the 320–400 nm wavelength range produced by unknown chemistry. We investigate electronic transitions in molecules that may exist in the atmosphere of Venus. We identify two different S2O2 isomers, cis-OSSO and trans-OSSO, which are formed...... are similar to those of sulfur monoxide (SO), generally thought to be the second most abundant sulfur oxide on Venus....

  1. Near-UV Sources in the Hubble Ultra Deep Field: The Catalog

    CERN Document Server

    Voyer, Elysse N; Siana, Brian; Gardner, Jonathan P; Quirk, Cori; Teplitz, Harry I

    2009-01-01

    The catalog from the first high resolution U-band image of the Hubble Ultra Deep Field, taken with Hubble's Wide Field Planetary Camera 2 through the F300W filter, is presented. We detect 96 U-band objects and compare and combine this catalog with a Great Observatories Origins Deep Survey (GOODS) B-selected catalog that provides B, V, i, and z photometry, spectral types, and photometric redshifts. We have also obtained Far-Ultraviolet (FUV, 1614 \\AA) data with Hubble's Advanced Camera for Surveys Solar Blind Channel (ACS/SBC) and with Galaxy Evolution Explorer (GALEX). We detected 31 sources with ACS/SBC, 28 with GALEX/FUV, and 45 with GALEX/NUV. The methods of observations, image processing, object identification, catalog preparation, and catalog matching are presented.

  2. Star Formation and AGN Activity in Interacting Galaxies: A Near-UV Perspective

    CERN Document Server

    Scott, Caroline

    2013-01-01

    We study nearby galaxies in close pairs to study the key factors affecting star formation and AGN activity triggered during galaxy interactions. Close pairs are selected from the Sloan Digital Sky Survey assuming a projected separation of $<$30kpc and recessional velocity difference $<$500km s$^{-1}$. Near-ultraviolet (NUV) fluxes from GALEX are used to estimate specific star formation rates (SSFRs). We find a factor of $\\sim$5.3 increase in SSFR for low mass (10$^{8}-10^{11}$M$_{\\odot}$) close pair galaxies and a factor of $\\sim$2.1 increase in SSFR for high mass mass (10$^{11}-10^{13}$M$_{\\odot}$) close pairs compared to the general galaxy population. Considering galaxies of all masses, we find a factor of $\\sim$1.8 enhancement in SSFR for close pairs in field environments compared to non-pairs, with no significant increase for pairs in group and cluster environments. A modest decrease of a factor of $\\sim$1.4 is found in the Seyfert fraction in close pair galaxies when compared to isolated galaxies, ...

  3. Near-UV cyanobacteriochrome signaling system elicits negative phototaxis in the cyanobacterium Synechocystis sp. PCC 6803

    OpenAIRE

    Song, Ji-Young; Cho, Hye Sun; Cho, Jung-Il; Jeon, Jong-Seong; Lagarias, J. Clark; Park, Youn-Il

    2011-01-01

    Positive phototaxis systems have been well studied in bacteria; however, the photoreceptor(s) and their downstream signaling components that are responsible for negative phototaxis are poorly understood. Negative phototaxis sensory systems are important for cyanobacteria, oxygenic photosynthetic organisms that must contend with reactive oxygen species generated by an abundance of pigment photosensitizers. The unicellular cyanobacterium Synechocystis sp. PCC6803 exhibits type IV pilus-dependen...

  4. Modeling the near-UV band of GK stars, Paper III: Dependence on abundance pattern

    CERN Document Server

    Short, C Ian

    2013-01-01

    We extend the grid of NLTE models presented in Paper II to explore variations in abundance pattern in two ways: 1) The adoption of the Asplund et al. (2009) (GASS10) abundances, 2) For stars of metallicity, [M/H], of -0.5, the adoption of a non-solar enhancement of alpha-elements by +0.3 dex. Moreover, our grid of synthetic spectral energy distributions (SEDs) is interpolated to a finer numerical resolution in both T_eff (Delta T_eff = 25 K) and log g (Delta log g = 0.25). We compare the values of T_eff and log g inferred from fitting LTE and Non-LTE SEDs to observed SEDs throughout the entire visible band, and in an ad hoc "blue" band. We compare our spectrophotometrically derived T_eff values to a variety of T_eff calibrations, including more empirical ones, drawn from the literature. For stars of solar metallicity, we find that the adoption of the GASS10 abundances lowers the inferred T_eff value by 25 - 50 K for late-type giants, and NLTE models computed with the GASS10 abundances give T_eff results that ...

  5. Ozone ground-based measurements by the GASCOD near-UV and visible DOAS system

    Science.gov (United States)

    Giovanelli, G.; Bonasoni, P.; Cervino, M.; Evangelisti, F.; Ravegnani, F.

    1994-01-01

    GASCOD, a near-ultraviolet and visible differential optical spectrometer, was developed at CNR's FISBAT Institute in Bologna, Italy, and first tested at Terra Nova Bay station in Antarctica (74.6 deg S, 164.6 deg E) during the summer expeditions 1988-1990 of PNRA (PNRA is the national research program in Antarctica, 'Programma Nazionale di Ricerche in Atartide'). A comparison with coincident O3 total column measurements taken in the same Antarctic area is presented, as is another comparison performed in Italy. Also introduced is an updated model for solar zenith measurements taken from a ground-based, upward-looking GASCOD spectrometer, which was employed for the 1991-92 winter campaign at Aer-Ostersund in Sweden (63.3 deg N, 13.1 deg E) during AESOE (European Arctic Stratospheric Ozone Experiment). The GASCOD can examine the spectra from 300 to 700 nm, in 50 nm steps, by moving the spectrometer's grating. At present, it takes measurements of solar zenith radiation in the 310-342 nm range for O3 and in the 405-463 nm range for NO2.

  6. Complex refractive indices of Saharan dust samples at visible and near UV wavelengths: a laboratory study

    Directory of Open Access Journals (Sweden)

    R. Wagner

    2011-07-01

    Full Text Available We have retrieved the wavelength-dependent imaginary parts of the complex refractive index for five different Saharan dust aerosol particles of variable mineralogical composition at wavelengths between 305 and 955 nm. The dust particles were generated by re-dispersing soil samples into a laboratory aerosol chamber, typically yielding particle sizes with mean diameters ranging from 0.3 to 0.4 μm and maximum diameters from 2 to 4 μm. The extinction and absorption coefficients as well as the number size distribution of the dust particles were simultaneously measured by various established techniques. An inversion scheme based on a spheroidal dust model was employed to deduce the refractive indices. The retrieved imaginary parts of the complex refractive index were in the range from 0.003 to 0.005, 0.005 to 0.011, and 0.016 to 0.050 at the wavelengths 955, 505, and 305 nm. The hematite content of the dust particles was determined by electron-microscopical single particle analysis. Hematite volume fractions in the range from 1.1 to 2.7 % were found for the different dusts, a range typical for atmospheric mineral dust. We have performed a sensitivity study to assess how accurately the retrieved imaginary refractive indices could be reproduced by calculations with mixing rule approximations using the experimentally determined hematite contents as input.

  7. Near UV imager with an MCP-based photon counting detector

    Science.gov (United States)

    Ambily, S.; Mathew, Joice; Sarpotdar, Mayuresh; Sreejith, A. G.; Nirmal, K.; Prakash, Ajin; Safonova, Margarita; Murthy, Jayant

    2016-07-01

    We are developing a compact UV Imager using light weight components, that can be own on a small CubeSat or a balloon platform. The system has a lens-based optics that can provide an aberration-free image over a wide field of view. The backend instrument is a photon counting detector with off-the-shelf MCP, CMOS sensor and electronics. We are using a Z-stack MCP with a compact high voltage power supply and a phosphor screen anode, which is read out by a CMOS sensor and the associated electronics. The instrument can be used to observe solar system objects and detect bright transients from the upper atmosphere with the help of CubeSats or high altitude balloons. We have designed the imager to be capable of working in direct frame transfer mode as well in the photon-counting mode for single photon event detection. The identification and centroiding of each photon event are done using an FPGA-based data acquisition and real-time processing system.

  8. Selective removal of composite sealants with near-UV laser pulses

    Science.gov (United States)

    Louie, Tiffany M.; Jones, Robert S.; Sarma, Anupama V.; Fried, Daniel

    2004-05-01

    It is often necessary to replace pit and fissure sealants and composite restorations. This task is complicated by the necessity for complete removal of the remaining composite to enable suitable adhesion of new composite. Previous studies have shown that lasers pulses from a frequency-tripled Nd:YAG laser (355-nm) can selectively remove residual composite after orthodontic bracket removal on enamel surfaces. UV laser light is preferentially absorbed by polymeric resins and the organic content of the tooth enamel. The objective of this study was to determine if such laser pulses are suitable for selective removal of the old composite from pit and fissure sealants and restorations without damaging surrounding sound tissues. Optical coherence tomography was used to acquire optical cross sections of the occlusal topography and peripheral tooth structure non-destructively before application of the sealants, after sealant application, and after sealant removal with 355-nm laser pulses with intensities ranging from 0-10 J/cm2. Thermocouples were used to monitor the temperature in the pulp chamber during composite removal under clinically relevant ablation rates, i.e., 30 Hz and 30 mJ per laser pulse. At an irradiation intensity of 1.3 J/cm2 pit and fissure sealants were completely removed without visible damage to the underlying enamel. At intensities above 1.5 J/cm2, the laser removes the resin layer while at the same time preferentially etching the surface of the enamel. Temperature excursions in the pulp chamber of extracted teeth was limited to less than 5°C if air-cooling was used during the rapid removal (1-2 min) of sealants, water-cooling was not needed. This is the first presentation of a method for the selective removal of composite restorative materials without damage to the underlying sound tooth structure.

  9. Near-UV to near-IR disk-averaged Earth's reflectance spectra

    CERN Document Server

    Hamdani, S; Foellmi, C; Berthier, J; Briot, D; François, P; Riaud, P; Schneider, J

    2005-01-01

    We report 320 to 1020nm disk-averaged Earth reflectance spectra obtained from Moon's Earthshine observations with the EMMI spectrograph on the NTT at ESO La Silla (Chile). The spectral signatures of Earth atmosphere and ground vegetation are observed. A vegetation red-edge of up to 9% is observed on Europe and Africa and ~2% upon Pacific Ocean. The spectra also show that Earth is a blue planet when Rayleigh scattering dominates, or totally white when the cloud cover is large.

  10. Near-UV Sources in the Hubble Ultra Deep Field: The Catalog

    Science.gov (United States)

    Gardner, Jonathan P.; Voyrer, Elysse; de Mello, Duilia F.; Siana, Brian; Quirk, Cori; Teplitz, Harry I.

    2009-01-01

    The catalog from the first high resolution U-band image of the Hubble Ultra Deep Field, taken with Hubble s Wide Field Planetary Camera 2 through the F300W filter, is presented. We detect 96 U-band objects and compare and combine this catalog with a Great Observatories Origins Deep Survey (GOODS) B-selected catalog that provides B, V, i, and z photometry, spectral types, and photometric redshifts. We have also obtained Far-Ultraviolet (FUV, 1614 Angstroms) data with Hubble s Advanced Camera for Surveys Solar Blind Channel (ACS/SBC) and with Galaxy Evolution Explorer (GALEX). We detected 31 sources with ACS/SBC, 28 with GALEX/FUV, and 45 with GALEX/NUV. The methods of observations, image processing, object identification, catalog preparation, and catalog matching are presented.

  11. Prospects and merits of metal-clad semiconductor lasers from nearly UV to far IR

    CERN Document Server

    Khurgin, Jacob B

    2015-01-01

    Using metal-clad (or plasmonic) waveguide structures in semiconductor lasers carries a promise of reduced size, threshold, and power consumption. This promise is put to a rigorous theoretical test, that takes into account increased waveguide loss, Auger recombination, and Purcell enhancement of spontaneous recombination. The conclusion is that purported benefits of metal waveguides are small to nonexistent for all the band-to-band and intersubband lasers operating from UV to Mid-IR range, with a prominent exception of far-IR and THz quantum cascade lasers. For these devices, however, metal waveguides already represent the state of the art, and the guiding mechanism in them has far more in common with a ubiquitous transmission line than with plasmonics.

  12. Nebular Continuum and Line Emission in Stellar Population Synthesis Models

    CERN Document Server

    Byler, Nell; Conroy, Charlie; Johnson, Benjamin D

    2016-01-01

    Accounting for nebular emission when modeling galaxy spectral energy distributions (SEDs) is important, as both line and continuum emission can contribute significantly to the total observed flux. In this work, we present a new nebular emission model integrated within the Flexible Stellar Population Synthesis code that computes the total line and continuum emission for complex stellar populations using the photoionization code Cloudy. The self-consistent coupling of the nebular emission to the matched ionizing spectrum produces emission line intensities that correctly scale with the stellar population as a function of age and metallicity. This more complete model of galaxy SEDs will improve estimates of global gas properties derived with diagnostic diagrams, star formation rates based on H$\\alpha$, and stellar masses derived from NIR broadband photometry. Our models agree well with results from other photoionization models and are able to reproduce observed emission from H II regions and star-forming galaxies...

  13. Emission Inventory for Fugitive Emissions in Denmark

    DEFF Research Database (Denmark)

    Plejdrup, Marlene Schmidt; Nielsen, Ole-Kenneth; Nielsen, Malene

    This report presents the methodology and data used in the Danish inventory of fugitive emissions from fuels for the years until 2007. The inventory of fugitive emissions includes CO2, CH4, N2O, NOx, CO, NMVOC, SO2, dioxin, PAH and particulate matter. In 2007 the total Danish emission of greenhouse...

  14. Egret observations of the extragalactic gamma-ray emission

    DEFF Research Database (Denmark)

    Sreekumar, P.; Bertsch, D.L.; Dingus, B.L.

    1998-01-01

    with the local interstellar gas and radiation, as well as an almost uniformly distributed component that is generally believed to originate outside the Galaxy. Through a careful study and removal of the Galactic diffuse emission, the flux, spectrum, and uniformity of the extragalactic emission are deduced......The all-sky survey in high-energy gamma rays (E > 30 MeV) carried out by EGRET aboard the Compton Gamma Ray Observatory provides a unique opportunity to examine in detail the diffuse gamma-ray emission. The observed diffuse emission has a Galactic component arising from cosmic-ray interactions...

  15. The First Spectrum of the Coldest Brown Dwarf

    CERN Document Server

    Skemer, Andrew; Allers, Katelyn; Geballe, Thomas; Marley, Mark; Fortney, Jonathan; Faherty, Jacqueline; Bjoraker, Gordon; Lupu, Roxana

    2016-01-01

    The recently discovered brown dwarf WISE 0855 presents our first opportunity to directly study an object outside the Solar System that is nearly as cold as our own gas giant planets. However the traditional methodology for characterizing brown dwarfs---near infrared spectroscopy---is not currently feasible as WISE 0855 is too cold and faint. To characterize this frozen extrasolar world we obtained a 4.5-5.2 $\\mu$m spectrum, the same bandpass long used to study Jupiter's deep thermal emission. Our spectrum reveals the presence of atmospheric water vapor and clouds, with an absorption profile that is strikingly similar to Jupiter. The spectrum is high enough quality to allow the investigation of dynamical and chemical processes that have long been studied in Jupiter's atmosphere, but now on an extrasolar world.

  16. The Solar Convection Spectrum

    Science.gov (United States)

    Bachmann, Kurt T.

    2000-01-01

    I helped to complete a research project with NASA scientists Dr. David Hathaway (my mentor), Rick Bogart, and John Beck from the SOHO/SOI collaboration. Our published paper in 'Solar Physics' was titled 'The Solar Convection Spectrum' (April 2000). Two of my undergraduate students were named on the paper--Gavrav Khutri and Josh Petitto. Gavrav also wrote a short paper for the National Conference of Undergraduate Research Proceedings in 1998 using a preliminary result. Our main result was that we show no evidence of a scale of convection named 'mesogranulation'. Instead, we see only direct evidence for the well-known scales of convection known as graduation and supergranulation. We are also completing work on vertical versus horizontal flow fluxes at the solar surface. I continue to work on phase relationships of solar activity indicators, but I have not yet written a paper with my students on this topic. Along with my research results, I have developed and augmented undergraduate courses at Birmingham-Southern College by myself and with other faculty. We have included new labs and observations, speakers from NASA and elsewhere, new subject material related to NASA and space science. I have done a great deal of work in outreach, mostly as President and other offices in the Birmingham Astronomical Society. My work includes speaking, attracting speakers, giving workshops, and governing.

  17. PINS Spectrum Identification Guide

    Energy Technology Data Exchange (ETDEWEB)

    A.J. Caffrey

    2012-03-01

    The Portable Isotopic Neutron Spectroscopy—PINS, for short—system identifies the chemicals inside munitions and containers without opening them, a decided safety advantage if the fill chemical is a hazardous substance like a chemical warfare agent or an explosive. The PINS Spectrum Identification Guide is intended as a reference for technical professionals responsible for the interpretation of PINS gamma-ray spectra. The guide is divided into two parts. The three chapters that constitute Part I cover the science and technology of PINS. Neutron activation analysis is the focus of Chapter 1. Chapter 2 explores PINS hardware, software, and related operational issues. Gamma-ray spectral analysis basics are introduced in Chapter 3. The six chapters of Part II cover the identification of PINS spectra in detail. Like the PINS decision tree logic, these chapters are organized by chemical element: phosphorus-based chemicals, chlorine-based chemicals, etc. These descriptions of hazardous, toxic, and/or explosive chemicals conclude with a chapter on the identification of the inert chemicals, e.g. sand, used to fill practice munitions.

  18. Rotational Spectrum of Saccharine

    Science.gov (United States)

    Alonso, Elena R.; Mata, Santiago; Alonso, José L.

    2017-06-01

    A significant step forward in the structure-activity relationships of sweeteners was the assignment of the AH-B moiety in sweeteners by Shallenberger and Acree. They proposed that all sweeteners contain an AH-B moiety, known as glucophore, in which A and B are electronegative atoms separated by a distance between 2.5 to 4 Å. H is a hydrogen atom attached to one of the electronegative atom by a covalent bond. For saccharine, one of the oldest artificial sweeteners widely used in food and drinks, two possible B moieties exist ,the carbonyl oxygen atom and the sulfoxide oxygen atom although there is a consensus of opinion among scientists over the assignment of AH-B moieties to HN-SO. In the present work, the solid of saccharine (m.p. 220°C) has been vaporized by laser ablation (LA) and its rotational spectrum has been analyzed by broadband CP-FTMW and narrowband MB-FTMW Fourier transform microwave techniques. The detailed structural information extracted from the rotational constants and ^{14}N nuclear quadrupole coupling constants provided enough information to ascribe the glucophore's AH and B sites of saccharine. R. S. Shallenberger, T. E. Acree. Nature 216, 480-482 Nov 1967. R. S. Shallenberger. Taste Chemistry; Blackie Academic & Professional, London, (1993).

  19. The Cu II Spectrum

    Directory of Open Access Journals (Sweden)

    Alexander Kramida

    2017-02-01

    Full Text Available New wavelength measurements in the vacuum ultraviolet (VUV, ultraviolet and visible spectral regions have been combined with available literature data to refine and extend the description of the spectrum of singly ionized copper (Cu II. In the VUV region, we measured 401 lines using a concave grating spectrograph and photographic plates. In the UV and visible regions, we measured 276 lines using a Fourier-transform spectrometer. These new measurements were combined with previously unpublished data from the thesis of Ross, with accurate VUV grating measurements of Kaufman and Ward, and with less accurate older measurements of Shenstone to construct a comprehensive list of ≈2440 observed lines, from which we derived a revised set of 379 optimized energy levels, complemented with 89 additional levels obtained using series formulas. Among the 379 experimental levels, 29 are new. Intensities of all lines observed in different experiments have been reduced to the same uniform scale by using newly calculated transition probabilities (A-values. We combined our calculations with published measured and calculated A-values to provide a set of 555 critically evaluated transition probabilities with estimated uncertainties, 162 of which are less than 20%.

  20. The worldwide leaf economics spectrum

    NARCIS (Netherlands)

    Wright, I.J.; Reich, P.B.; Westoby, M.; Ackerly, D.D.; Baruch, Z.; Bongers, F.J.J.M.; Cavender-Bares, J.; Chapin, T.; Cornelissen, J.H.C.; Diemer, M.; Flexas, J.; Garnier, E.; Groom, P.K.; Gulias, J.; Hikosaka, K.; Lamont, B.B.; Lee, T.; Lee, W.; Lusk, C.; Midgley, J.J.; Navas, M.L.; Niinements, Ü.; Oleksyn, J.; Osada, N.; Poorter, H.; Poot, P.; Prior, L.; Pyankov, V.I.; Roumet, C.; Thomas, S.C.; Tjoelker, M.G.; Veneklaas, E.J.; Villar, R.

    2004-01-01

    Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients

  1. The spectrum of spinning superparticles

    NARCIS (Netherlands)

    Bergshoeff, E.; Holten, J.W. van

    1989-01-01

    We construct the action and transformation rules of a massless spinning superparticle in D dimensions which has N worldline as well as M target space supersymmetries. The spectrum of physical states for different values of N, M and D is presented. We also discuss the action, symmetries and spectrum

  2. Dynamic Spectrum Sharing among Femtocells

    DEFF Research Database (Denmark)

    Da Costa, Gustavo Wagner Oliveira

    2012-01-01

    The ever-growing demand for mobile broadband is leading to an imminent spectrum scarcity. In order to cope with such situation dynamic spectrum sharing and the widespread deployment of small cells (femtocells) are promising solutions. Delivering such a view is not short of challenges. Massive dep...

  3. Spectrum properties analysis of different soil moisture content

    Science.gov (United States)

    Fang, Shenghui; Hu, Bo; Lin, Fan

    2009-10-01

    Soil moisture content is one of the most important factors in soil business. The basic of detecting soil moisture content using remote sensing technology is to analyze the relationship between soil moisture content and emissivity. In this paper, based on the analysis of spectrum collection and processing by a portable spectrometer, a set of measure schemes were first established which can accurately measure the reflectivity and emissivity of soil spectrum with different moisture content in near-infrared and thermal infrared bands. Then we selected different bare soil areas as the areas for survey, and studied the relationship of different moisture content and the spectrum curve in the soil both of the same kind and of different kind (like the soil whose structure has been modified caused by the change of organic matter contents or soil particle size). Finally, we emphasized on the quantitative relationship between soil reflectivity & emissivity and soil moisture content using the test data, and establish a model depicting the quantitative relationship above in near-infrared and thermal infrared bands.

  4. Retrieving capillary-gravity wave spectrum from polarimetric microwave radiation of ocean surface

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A new simple two-scale model on the polarimetric microwave emission of ocean surface is derived at first, which can be ex-pressed as an integral of weighting functions (M0 and M2) and ocean surface curvature spectrum coefficients (C0 and C2). This provides a simple way to investigate the effect of curvature spectrum on ocean emission. It is found that ocean waves with wavelengths both comparable to and much greater than the electromagnetic wavelength can contribute to the harmonics of ocean surface microwave emission, depending on the magnitude of the ocean surface spectrum in these length scales. Bright-ness temperature predictions differ significantly due to present diverse spectrum models, and thus a study on wave spectrum obtained inversely from brightness temperature measurements is necessary. From the ocean surface radiation data measured by polarimetric microwave radiometer, we derived an ocean wave spectrum with a wider wave number range, using the proposed two-scale model and constrained linear least-squares method. The derived ocean wave spectrum is useful for comparing with present diverse models.

  5. The variable XMM-Newton spectrum of Markarian 766

    CERN Document Server

    Page, M J; Carrera, F J; Clavel, J; Kaastra, J S; Puchnarewicz, E M; Santos-Lleó, M; Brunner, H; Ferrigno, C; George, I M; Paerels, F B S; Pounds, K A; Trudolyubov, S P

    2001-01-01

    The narrow-line Seyfert 1 galaxy Markarian 766 was observed for 60 ks with the XMM-Newton observatory. The source shows a complex X-ray spectrum. The 2-10 keV spectrum can be adequately represented by a power law and broad Fe Ka emission. Between 0.7 and 2 keV the spectrum is harder and exhibits a flux deficit with respect to the extrapolated medium energy slope. Below 0.7 keV, however, there is a strong excess of emission. The RGS spectrum shows an edge-like feature at 0.7 keV; the energy of this feature is inconsistent with that expected for an OVII edge from a warm absorber. Markarian 766 varies by a factor of ~ 2 in overall count rate in the EPIC and RGS instruments on a timescale of a few thousand seconds, while no significant flux changes are observed in the ultraviolet with the OM. The X-ray variability is spectrally dependent with the largest amplitude variability occurring in the 0.4-2 keV band. The spectral variability can be explained by a change in flux and slope of the medium energy continuum emi...

  6. The X-ray Spectrum of Supernova Remnant 1987A

    CERN Document Server

    Michael, E; McCray, R; Hwang, U; Burrows, D N; Park, S; Garmire, G P; Holt, S S; Hasinger, G; Michael, Eli; Zhekov, Svetozar; Cray, Richard Mc; Hwang, Una; Burrows, David N.; Park, Sangwook; Garmire, Gordon P.; Holt, Stephen S.; Hasinger, Guenther

    2002-01-01

    We discuss the X-ray emission observed from Supernova Remnant 1987A with the Chandra X-ray Observatory. We analyze a high resolution spectrum obtained in 1999 October with the high energy transmission grating (HETG). From this spectrum we measure the strengths and an average profile of the observed X-ray lines. We also analyze a high signal-to-noise ratio CCD spectrum obtained in 2000 December. The good statistics (~ 9250 counts) of this spectrum and the high spatial resolution provided by the telescope allow us to perform spectroscopic analyses of different regions of the remnant. We discuss the relevant shock physics that can explain the observed X-ray emission. The X-ray spectra are well fit by plane parallel shock models with post-shock electron temperatures of ~ 2.6 keV and ionization ages of ~ 6 x 10^10 cm^3/s. The combined X-ray line profile has a FWHM of ~ 5000 km/s, indicating a blast wave speed of ~ 3500 km/s. At this speed, plasma with a mean post-shock temperature of ~ 17 keV is produced. This is ...

  7. Comparison of RF spectrum prediction methods for dynamic spectrum access

    Science.gov (United States)

    Kovarskiy, Jacob A.; Martone, Anthony F.; Gallagher, Kyle A.; Sherbondy, Kelly D.; Narayanan, Ram M.

    2017-05-01

    Dynamic spectrum access (DSA) refers to the adaptive utilization of today's busy electromagnetic spectrum. Cognitive radio/radar technologies require DSA to intelligently transmit and receive information in changing environments. Predicting radio frequency (RF) activity reduces sensing time and energy consumption for identifying usable spectrum. Typical spectrum prediction methods involve modeling spectral statistics with Hidden Markov Models (HMM) or various neural network structures. HMMs describe the time-varying state probabilities of Markov processes as a dynamic Bayesian network. Neural Networks model biological brain neuron connections to perform a wide range of complex and often non-linear computations. This work compares HMM, Multilayer Perceptron (MLP), and Recurrent Neural Network (RNN) algorithms and their ability to perform RF channel state prediction. Monte Carlo simulations on both measured and simulated spectrum data evaluate the performance of these algorithms. Generalizing spectrum occupancy as an alternating renewal process allows Poisson random variables to generate simulated data while energy detection determines the occupancy state of measured RF spectrum data for testing. The results suggest that neural networks achieve better prediction accuracy and prove more adaptable to changing spectral statistics than HMMs given sufficient training data.

  8. Effects of transparent inorganic pigment on spectral properties of spectrum-fingerprint anti-counterfeiting fiber containing rare earths

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jishu; GE Mingqiao

    2012-01-01

    Transparent inorganic pigment is the color-filler material for manufacturing spectrum-fingerprint anti-counterfeiting fiber,and has great effects on the emission spectral characteristics of the fiber.In order to explain the change mechanism of the emission spectral characteristics of spectrum-fingerprint anti-counterfeiting fiber and to promote the development of the fiber,several kinds of spectrum-fingerprint fiber samples were prepared by using rare-earth strontium aluminate and polyethylene terephthalate (PET) as raw materials and by adding different kinds of transparent inorganic pigments respectively in this research.The effect of transparent inorganic pigment on the spectral characteristics of the fiber was analyzed in detail by means of scanning electron microscopy (SEM),X-ray diffraction (XRD) and fluorescence spectrometer.The results showed that transparent inorganic pigment had no effect on the dispersion state and phase structure of rare-earth luminescent material in spectrum-fingerprint fiber and the microscopic morphology of the fiber.However,transparent inorganic pigment did affect the excitation and emission process of spectrum-fingerprint fiber so as to decrease its excitation and emission efficiency.The change of both the type and content of transparent inorganic pigment exerted great effects on the excitation and emission spectra of the fiber.Therefore,it was a feasible way to control the emission spectrum of spectntm-fmgerprint fiber through changing the type and content of transparent inorganic pigment.

  9. Simulation of UIB spectra with IR emission from CHONS molecules

    CERN Document Server

    Papoular, Renaud

    2012-01-01

    The present work purports to identify candidate carriers of the UIBs. This requires a procedure for the computation of the emission spectrum of any given candidate. The procedure used here consists in exciting the carrier into a state of internal vibration, waiting until the system has reached dynamic equilibrium and, then, monitoring the time variations of the overall electric dipole moment associated with this vibration. The emission spectrum is shown to be simply related to the FT of these variations. This procedure was applied to more than 100 different chemical structures, inspired by the exhaustive experimental and theoretical analyses of Kerogens, the terrestrial sedimentary matter, which is known to be mainly composed of C, H, O, N and S atoms. From this data base, 21 structures were extracted, which fall in 4 classes, each of which contributes preferentially to one of the main UIBs. Summing their adequately weighted spectra delivers an emission spectrum which indeed exhibits the main UIB features (al...

  10. A Guided-Inquiry Lab for the Analysis of the Balmer Series of the Hydrogen Atomic Spectrum

    Science.gov (United States)

    Bopegedera, A. M. R. P.

    2011-01-01

    A guided-inquiry lab was developed to analyze the Balmer series of the hydrogen atomic spectrum. The emission spectrum of hydrogen was recorded with a homemade benchtop spectrophotometer. By drawing graphs and a trial-and-error approach, students discover the linear relationship presented in the Rydberg formula and connect it with the Bohr model…

  11. Infrared absorption and emission characteristics of interstellar PAHs

    Science.gov (United States)

    Barker, J. R.; Allamandola, Louis J.; Tielens, Alexander G. G. M.; Barker, J. R.; Barker, J. R.

    1986-01-01

    The mid-infrared interstellar emission spectrum with features at 3.28, 6.2, 7.7, 8.7 and 11.3 microns is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis, which is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the IR and Raman properties are discussed. Interstellar IR band emission is due to relaxation from highly vibrationally excited PAHs excited by ultraviolet photons. The excitation/emission process is described and the IR fluorescence from one PAH, chrysene, is traced. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs contain between 20 and 30 carbon atoms are responsible for the emission.

  12. True CMB Power Spectrum Estimation

    CERN Document Server

    Paykari, P; Fadili, M J

    2012-01-01

    The cosmic microwave background (CMB) power spectrum is a powerful cosmological probe as it entails almost all the statistical information of the CMB perturbations. Having access to only one sky, the CMB power spectrum measured by our experiments is only a realization of the true underlying angular power spectrum. In this paper we aim to recover the true underlying CMB power spectrum from the one realization that we have without a need to know the cosmological parameters. The sparsity of the CMB power spectrum is first investigated in two dictionaries; Discrete Cosine Transform (DCT) and Wavelet Transform (WT). The CMB power spectrum can be recovered with only a few percentage of the coefficients in both of these dictionaries and hence is very compressible in these dictionaries. We study the performance of these dictionaries in smoothing a set of simulated power spectra. Based on this, we develop a technique that estimates the true underlying CMB power spectrum from data, i.e. without a need to know the cosmo...

  13. A green fluorescent protein with photoswitchable emission from the deep sea.

    Directory of Open Access Journals (Sweden)

    Alexander Vogt

    Full Text Available A colorful variety of fluorescent proteins (FPs from marine invertebrates are utilized as genetically encoded markers for live cell imaging. The increased demand for advanced imaging techniques drives a continuous search for FPs with new and improved properties. Many useful FPs have been isolated from species adapted to sun-flooded habitats such as tropical coral reefs. It has yet remained unknown if species expressing green fluorescent protein (GFP-like proteins also exist in the darkness of the deep sea. Using a submarine-based and -operated fluorescence detection system in the Gulf of Mexico, we discovered ceriantharians emitting bright green fluorescence in depths between 500 and 600 m and identified a GFP, named cerFP505, with bright fluorescence emission peaking at 505 nm. Spectroscopic studies showed that approximately 15% of the protein bulk feature reversible ON/OFF photoswitching that can be induced by alternating irradiation with blue und near-UV light. Despite being derived from an animal adapted to essentially complete darkness and low temperatures, cerFP505 maturation in living mammalian cells at 37 degrees C, its brightness and photostability are comparable to those of EGFP and cmFP512 from shallow water species. Therefore, our findings disclose the deep sea as a potential source of GFP-like molecular marker proteins.

  14. Evidence of delayed light emission of TetraPhenyl Butadiene excited by liquid Argon scintillation light

    CERN Document Server

    Segreto, Ettore

    2014-01-01

    TetraPhenyl Butadiene is the wavelength shifter most widely used in combination with liquid Argon. The latter emits scintillation photons with a wavelength of 127 nm that need to be downshifted to be detected by photomultipliers with glass or quartz windows. TetraPhenyl Butadiene has been demonstrated to have an extremely high conversion efficiency, possibly higher than 100% for 127 nm photons, while there is no precise information about the time dependence of its emission. It is usually assumed to be exponentially decaying with a characteristic time of the order of one ns, as an extrapolation from measurements with exciting radiation in the near UV. This work shows that TetraPhenyl Butadiene, when excited by 127 nm photons, reemits photons not only with a very short decay time, but also with slower ones due to triplet states de-excitations. This fact can strongly contribute to clarify the anomalies of liquid Argon scintillation light reported in literature since seventies, namely the inconsistency in the mea...

  15. Constraining isocurvature perturbations with the 21cm emission from minihaloes

    OpenAIRE

    Takeuchi, Yoshitaka; Chongchitnan, Sirichai

    2013-01-01

    We investigate the effects of isocurvature perturbations on the 21cm radiation from minihaloes (MHs) at high redshifts and examine constraints on the isocurvature amplitude and power spectrum using the next generation of radio telescopes such as the Square Kilometre Array. We find that there is a realistic prospect of observing the isocurvature imprints in the 21cm emission from MHs, but only if the isocurvature spectral index is close to $3$ (i.e., the spectrum is blue). When the isocurvatur...

  16. DEVELOPING SPEED DEPENDENT EMISSION FACTORS USING ON-BOARD EMISSION MEASURING EQUIPMENT IN INDIA

    Directory of Open Access Journals (Sweden)

    Sushant Sharma

    2016-09-01

    Full Text Available Vehicular emission models are important tools in several environmental impact studies. Although several studies have been conducted for emission control purposes, few attempts have been made on the planning side. For instance, long-term transportation network capacity improvement models do not explicitly consider emission in the objective function. Incorporating vehicular emission into the objective function is effective only if speed dependent emission factor is used in the estimation of emission. Although this issue is well addressed in the developed countries, owing to the heterogeneity of vehicles and absence of speed dependent emission factors the benefit from network investment is often underestimated in developing countries like India. Therefore, an attempt is made to explore the possibility of developing speed dependent emission factor for Indian conditions and vehicles. For accurate measurement an onboard test is conducted on typical vehicles; namely, a passenger car, a sports utility vehicle, and a truck. On board test equipment collected the data while the vehicle traversed with different speed ranges. The data obtained is processed and used for developing emission factor in the form of second degree polynomial with speed as the dependent variable. The emission factors for the three types of vehicles and for CO, CO2, NOX, and HC are developed. The results have been compared with Indian driving cycle based emission factors as well as UK based speed dependent emission factors for car in particular. The study gave a preliminary insight into the behaviors of pollutants with respect to speed. However, there is a need to develop such factor using large spectrum of vehicles and diverse driving conditions.

  17. Fundamentals of spread spectrum modulation

    CERN Document Server

    Ziemer, Rodger E

    2007-01-01

    This lecture covers the fundamentals of spread spectrum modulation, which can be defined as any modulation technique that requires a transmission bandwidth much greater than the modulating signal bandwidth, independently of the bandwidth of the modulating signal. After reviewing basic digital modulation techniques, the principal forms of spread spectrum modulation are described. One of the most important components of a spread spectrum system is the spreading code, and several types and their characteristics are described. The most essential operation required at the receiver in a spread spect

  18. Broad-spectrum antiviral agents

    Directory of Open Access Journals (Sweden)

    Jun-Da eZhu

    2015-05-01

    Full Text Available Development of highly effective, broad-spectrum antiviral agents is the major objective shared by the fields of virology and pharmaceutics. Antiviral drug development has focused on targeting viral entry and replication, as well as modulating cellular defense system. High throughput screening of molecules, genetic engineering of peptides, and functional screening of agents have identified promising candidates for development of optimal broad-spectrum antiviral agents to intervene in viral infection and control viral epidemics. This review discusses current knowledge, prospective applications, opportunities, and challenges in the development of broad-spectrum antiviral agents.

  19. CORA - emission line fitting with Maximum Likelihood

    Science.gov (United States)

    Ness, J.-U.; Wichmann, R.

    2002-07-01

    The advent of pipeline-processed data both from space- and ground-based observatories often disposes of the need of full-fledged data reduction software with its associated steep learning curve. In many cases, a simple tool doing just one task, and doing it right, is all one wishes. In this spirit we introduce CORA, a line fitting tool based on the maximum likelihood technique, which has been developed for the analysis of emission line spectra with low count numbers and has successfully been used in several publications. CORA uses a rigorous application of Poisson statistics. From the assumption of Poissonian noise we derive the probability for a model of the emission line spectrum to represent the measured spectrum. The likelihood function is used as a criterion for optimizing the parameters of the theoretical spectrum and a fixed point equation is derived allowing an efficient way to obtain line fluxes. As an example we demonstrate the functionality of the program with an X-ray spectrum of Capella obtained with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra observatory and choose the analysis of the Ne IX triplet around 13.5 Å.

  20. The far-infrared spectrum of the core of Sagittarius B2

    Science.gov (United States)

    Erickson, E. F.; Caroff, L. J.; Simpson, J. P.; Strecker, D. W.; Goorvitch, D.

    1977-01-01

    A Michelson interferometer aboard NASA's Kuiper Airborne Observatory has been used to measure the spectrum of Sgr B2 from 40 to 200 kaysers with 5-kayser resolution in a 1.4-arcmin beam. The measured spectrum is smooth and featureless with a broad maximum at about 85 kaysers. The data can be fitted analytically with a model corresponding to thermal emission by a uniform sla of dust filling the beam, with an average temperature of approximately 32 K, an optical depth at 100 microns of about 1.6, and a spectral index of the dust emissivity about 1.5. The absence of features implies either that the source is optically thick or that the emission spectrum of the individual grains is smooth in the passband. The possible physical significance of this model is discussed.

  1. THE EFFECTS OF POLARIZED FOREGROUNDS ON 21 cm EPOCH OF REIONIZATION POWER SPECTRUM MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Moore, David F.; Aguirre, James E. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA (United States); Parsons, Aaron R.; Pober, Jonathan C. [Astronomy Department, University of California, Berkeley, Berkeley, CA (United States); Jacobs, Daniel C., E-mail: damo@sas.upenn.edu [School of Earth and Space Exploration, Arizona State University, Tempe, AZ USA (United States)

    2013-06-01

    Experiments aimed at detecting highly-redshifted 21 cm emission from the epoch of reionization (EoR) are plagued by the contamination of foreground emission. A potentially important source of contaminating foregrounds may be Faraday-rotated, polarized emission, which leaks into the estimate of the intrinsically unpolarized EoR signal. While these foregrounds' intrinsic polarization may not be problematic, the spectral structure introduced by the Faraday rotation could be. To better understand and characterize these effects, we present a simulation of the polarized sky between 120 and 180 MHz. We compute a single visibility, and estimate the three-dimensional power spectrum from that visibility using the delay spectrum approach presented in Parsons et al. Using the Donald C. Backer Precision Array to Probe the Epoch of Reionization as an example instrument, we show the expected leakage into the unpolarized power spectrum to be several orders of magnitude above the expected 21 cm EoR signal.

  2. AUTISM SPECTRUM DISORDERS (ASD

    Directory of Open Access Journals (Sweden)

    Middha Akanksha

    2011-05-01

    Full Text Available Autism or Autism Spectrum Disorders (ASD is a serious neurological disorder affecting communication skills, social interactions, adaptability in an individual, and also causes dramatic changes in behavioral patterns. This condition typically lasts throughout one’s lifetime and affects both, children as well as adults. Research has shown a tenfold increase in autism cases over the past decade and still rising at an alarming pace. The origins of autism are not known even to modern science. Autism exists at different levels in individuals affected by the disease and is classified into five types. Symptoms for autism are more pronounced and prevalent in children compared to adults. Though some studies attribute autism to gene abnormality, science is yet to furnish hard facts about exact autism causes. Scientists and doctors are also unanimous in their opinion that autism, as of yet, has no cure. Treatments of autism are widely available and help in alleviating the symptoms of autism which make living with the condition easier.Several factors work together in causing autism but isolation and identification of a chief cause or causes has yet to be accomplished by modern science. Some people mistakenly believe that autism is related to bad parenting, vaccinations, or malnutrition. But these misconceptions are due to improper knowledge related to the disease. Symptoms of autism usually surface within the first two years of birth in children. Autistic children usually avoid eye contact and are poor imitators of sound together with a disliking towards a change in routines as well as non adaptability to new environments. At present, there is an absence of medical tests which can diagnose autism. The diagnosis of autism is largely based on developmental history and behavioral patterns. Medicinal treatments of autism have a downside as autism patients develop resistance to certain drugs over long period of use. All types of autism demand a good plan of

  3. Cyclostationary Beacon for Assisting Spectrum Sensing in Opportunistic Spectrum Access

    Directory of Open Access Journals (Sweden)

    Thomas Kaiser

    2011-03-01

    Full Text Available Cognitive radio is a promising solution to the problem of spectrum scarcity by means of allowing secondary radio networks access the spectrum opportunistically. One of the most important issues in cognitive radio is how to detect existing over-the-air signals reliably. Not a few literatures have reported that signals could be detected via their inherent or embedded properties. However, this approach may not be reliable and flexible enough for all kinds of signals with different modulation types. In this paper, we propose a type of multitone beacon signal carrying cyclostationary signatures, which is able to enhance the reliability and efficiency of signal detection at low cost of spectrum overhead. This beacon not only can indicate the presence or absence of user signal but also can reveal some other information helpful to opportunistic spectrum access through the information bits carried on its cyclostationary signatures. It could be applied to device/network identification, indication of spectrum allocation and spectrum rendezvous, both for primary and secondary users. Based on our previous work reported in [1], the generation and detection algorithm of the beacon signal are extended with improved spectral efficiency. Performance is discussed with both computer simulation and testbed validation.

  4. NEAR-ULTRAVIOLET EXCESS IN SLOWLY ACCRETING T TAURI STARS: LIMITS IMPOSED BY CHROMOSPHERIC EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Ingleby, Laura; Calvet, Nuria; Bergin, Edwin; McClure, Melissa [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Herczeg, Gregory [Max-Planck-Institut fuer Extraterrestriche Physik, Postfach 1312, D-85741 Garching (Germany); Brown, Alexander; France, Kevin [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389 (United States); Alexander, Richard [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Edwards, Suzan [Department of Astronomy, Smith College, Northampton, MA 01063 (United States); Espaillat, Catherine; Brown, Joanna [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States); Gregory, Scott G.; Hillenbrand, Lynne [Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Roueff, Evelyne; Abgrall, Herve [LUTH and UMR 8102 du CNRS, Observatoire de Paris, Section de Meudon, Place J. Janssen, F-92195 Meudon (France); Valenti, Jeff [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Walter, Frederick [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Johns-Krull, Christopher [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States); Linsky, Jeffrey [JILA, University of Colorado and NIST, 440 UCB Boulder, CO 80309-0440 (United States); Ardila, David, E-mail: lingleby@umich.edu, E-mail: ncalvet@umich.edu, E-mail: gregoryh@mpe.mpg.de [NASA Herschel Science Center, California Institute of Technology, Mail Code 100-22, Pasadena, CA 91125 (United States); and others

    2011-12-20

    Young stars surrounded by disks with very low mass accretion rates are likely in the final stages of inner disk evolution and therefore particularly interesting to study. We present ultraviolet (UV) observations of the {approx}5-9 Myr old stars RECX-1 and RECX-11, obtained with the Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph on the Hubble Space Telescope, as well as optical and near-infrared spectroscopic observations. The two stars have similar levels of near-UV emission, although spectroscopic evidence indicates that RECX-11 is accreting and RECX-1 is not. The line profiles of H{alpha} and He I {lambda}10830 in RECX-11 show both broad and narrow redshifted absorption components that vary with time, revealing the complexity of the accretion flows. We show that accretion indicators commonly used to measure mass accretion rates, e.g., U-band excess luminosity or the Ca II triplet line luminosity, are unreliable for low accretors, at least in the middle K spectral range. Using RECX-1 as a template for the intrinsic level of photospheric and chromospheric emission, we determine an upper limit of 3 Multiplication-Sign 10{sup -10} M{sub Sun} yr{sup -1} for RECX-11. At this low accretion rate, recent photoevaporation models predict that an inner hole should have developed in the disk. However, the spectral energy distribution of RECX-11 shows fluxes comparable to the median of Taurus in the near-infrared, indicating that substantial dust remains. Fluorescent H{sub 2} emission lines formed in the innermost disk are observed in RECX-11, showing that gas is present in the inner disk, along with the dust.

  5. Spectroscopy of an unusual emission line M star

    Science.gov (United States)

    Schneider, Donald P.; Greenstein, Jesse L.; Schmidt, Maarten; Gunn, James E.

    1991-01-01

    Moderate-resolution spectroscopy of an unusual late-type faint emission-line star, PC 0025 + 0047, is reported. A very strong (greater than 250 A equivalent width) an H-alpha emission line was detected by the present automated line search algorithm. The spectrum was found to have two unresolved emission lines (H-alpha and H-beta) near zero velocity, superposed on the absorption spectrum of a very red M dwarf which has strong K I, and relatively weak bands of TiO. From the weakness of the subordinate lines of Na I (8192 A) and other spectral features, it is inferred that it is definitely a cooler, and probably fainter, analog of LHS 2924. The strength of the emission lines indicates that PC 0025 + 0447 is very young and may be a fading predecessor brown drawf at an estimated M(bol) approaching 14m at a distance of about 60 pc.

  6. Features of exoelectron emission in amorphous metallic alloys

    CERN Document Server

    Veksler, A S; Morozov, I L; Semenov, A L

    2001-01-01

    The peculiarities of the photothermostimulated exoelectron emission in amorphous metallic alloys of the Fe sub 6 sub 4 Co sub 2 sub 1 B sub 1 sub 5 composition are studied. It is established that the temperature dependences of the exoelectron emission spectrum adequately reflect the two-stage character of the amorphous alloy transition into the crystalline state. The exoelectron emission spectrum is sensitive to the variations in the modes of the studied sample thermal treatment. The thermal treatment of the amorphous metallic alloy leads to growth in the intensity of the exoelectrons yield. The highest growth in the intensify of the exoelectron emission was observed in the alloys at the initial stage of their crystallization

  7. Multiple stimulated emission fluorescence photoacoustic sensing and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gaoming [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Key Laboratory of OptoElectronic Science and Technology for Medicine, Ministry of Education, Fujian Normal University, Fuzhou 350007 (China); Gao, Fei; Feng, Xiaohua; Zheng, Yuanjin, E-mail: yjzheng@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Qiu, Yishen [Key Laboratory of OptoElectronic Science and Technology for Medicine, Ministry of Education, Fujian Normal University, Fuzhou 350007 (China)

    2016-07-04

    Multiple stimulated emission fluorescence photoacoustic (MSEF-PA) phenomenon is demonstrated in this letter. Under simultaneous illumination of pumping light and stimulated emission light, the fluorescence emission process is speeded up by the stimulated emission effect. This leads to nonlinear enhancement of photoacoustic signal while the quantity of absorbed photons is more than that of fluorescent molecules illuminated by pumping light. The electronic states' specificity of fluorescent molecular can also be labelled by the MSEF-PA signals, which can potentially be used to obtain fluorescence excitation spectrum in deep scattering tissue with nonlinearly enhanced photoacoustic detection. In this preliminary study, the fluorescence excitation spectrum is reconstructed by MSEF-PA signals through sweeping the wavelength of exciting light, which confirms the theoretical derivation well.

  8. Autism Spectrum Disorder and Fragile X Syndrome

    Science.gov (United States)

    ... Just Figuring Out CGG Repeats! Donate Print PDF Autism Spectrum Disorder and Fragile X Syndrome Fragile X ... known single gene cause of ASD What Is Autism Spectrum Disorder? Read my Story Autism spectrum disorder ( ...

  9. Autism Spectrum Disorder and Fragile X Syndrome

    Science.gov (United States)

    ... only after another family member has been diagnosed. Autism Spectrum Disorder and Fragile X Syndrome Fragile X ... known single gene cause of ASD What Is Autism Spectrum Disorder? Autism spectrum disorder (ASD) is a ...

  10. Genetics Home Reference: ataxia neuropathy spectrum

    Science.gov (United States)

    ... Understand Genetics Home Health Conditions ataxia neuropathy spectrum ataxia neuropathy spectrum Enable Javascript to view the expand/ ... boxes. Download PDF Open All Close All Description Ataxia neuropathy spectrum is part of a group of ...

  11. Longitudinal peak detected Schottky spectrum

    CERN Document Server

    Shaposhnikova, E

    2009-01-01

    The "peak detected Schottky" spectrum is a diagnostic used since the late seventies for beam observation in the SPS and now already applied to the LHC. This tool was always believed, however without proof, to give a good picture of the particle distribution in synchrotron frequencies similar to the longitudinal Schottky spectrum of unbunched beam for revolution frequencies.In this paper an analysis of this measurement technique is presented both in a general form and for the particular realisation in the SPS. In addition the limitations of the present experimental set-up are discussed together with possible improvements. The analysis shows that for an optimised experimental set-up the spectrum of the peak detected signal is very close to the synchrotron frequency distribution inside the bunch - much closer than that given by the traditional longitudinal bunched-beam Schottky spectrum.

  12. Ion cyclotron emission by spontaneous emission

    Energy Technology Data Exchange (ETDEWEB)

    Da Costa, O. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Gresillon, D. [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises

    1994-07-01

    The goal of the study is to examine whether the spontaneous emission can account for ICE (ion cyclotron emission) experimental results, or part of them. A straightforward approach to plasma emission is chosen, investigating the near equilibrium wave radiation by gyrating ions, and thus building from the majority and fast fusion ions the plasma fluctuations and emission on the fast magnetoacoustic or compressional Alfven wave mode in the IC frequency range. Similarities with the ICE experiments are shown: the emission temperature in the presence of fast ions (even in a very small amount), the strong fast ion emission increase with the harmonic, the fine double-line splitting of each peak, the linear but not proportional increase of the peak width with the harmonic. 3 refs., 2 figs.

  13. Correlated amplitude fluctuations of spontaneous otoacoustic emissions in six lizard species

    NARCIS (Netherlands)

    van Dijk, P; Manley, GA; Gallo, L

    Spontaneous otoacoustic emissions were recorded from 17 lizard ears (six species: Gerrhosaurus major, Iguana iguana, Basiliscus vittatus, Tupinambis teguixin, Varanus exanthematicus, and Cordylus tropidosternum), The spectrum of each recording contained multiple spectral peaks. For each peak, the

  14. Correlated amplitude fluctuations of spontaneous otoacoustic emissions in six lizard species

    NARCIS (Netherlands)

    van Dijk, P; Manley, GA; Gallo, L

    1998-01-01

    Spontaneous otoacoustic emissions were recorded from 17 lizard ears (six species: Gerrhosaurus major, Iguana iguana, Basiliscus vittatus, Tupinambis teguixin, Varanus exanthematicus, and Cordylus tropidosternum), The spectrum of each recording contained multiple spectral peaks. For each peak, the en

  15. Spectrum Trading in India and 5G

    DEFF Research Database (Denmark)

    Tripathi, Purnendu; Prasad, Ramjee

    2013-01-01

    Currently radio spectrum is largely managed through Command and Control method. Public mobile services require spectrum below 3 GHz for providing cost effective services. The existing method has created artificial shortage of spectrum especially below 3 GHz. Spectrum trading is a new concept in w...... for spectrum trading and it could provide a boost to the Indian telecom sector. Further, it will also discuss spectrum issue related with 5G in the direction of millimeter waves....

  16. Beyond the Spectrum: Rethinking Autism

    Directory of Open Access Journals (Sweden)

    Heather Thomas

    2017-03-01

    Full Text Available The "spectrum" has become the dominant metaphor for conceptualizing autism, with fundamental consequences for notions of disability, diversity, and normality. In this article, we draw on ethnographic research with autistic communities to explore how the notion of the autism spectrum has become a focus of explicit identification, reflection, and contestation. To further this inquiry, we place these debates into conversation with earlier debates regarding another spectrum—the Kinsey Scale, a "spectrum" for conceptualizing sexual orientation that first appeared in 1948 but has been critiqued since the 1970s. How might responses to the Kinsey Scale (like the Klein Grid contribute to rethinking the autism spectrum? This is a question about the cultural and political implications of metaphors and conceptual models. It is of broad importance because the spectrum metaphor is being extended to a range of conditions beyond autism itself. Our goal is thus to build on insights from sexuality studies as well as the insights of autistic persons, advocates, and researchers who wish to forestall the naturalization of "the spectrum." In doing so, we seek to contribute to a discussion of what alternative frameworks might bring to questions of social justice, ability, and human flourishing.

  17. Liquid-Arc/Spark-Excitation Atomic-Emission Spectroscopy

    Science.gov (United States)

    Schlagen, Kenneth J.

    1992-01-01

    Constituents of solutions identified in situ. Liquid-arc/spark-excitation atomic-emission spectroscopy (LAES) is experimental variant of atomic-emission spectroscopy in which electric arc or spark established in liquid and spectrum of light from arc or spark analyzed to identify chemical elements in liquid. Observations encourage development of LAES equipment for online monitoring of process streams in such industries as metal plating, electronics, and steel, and for online monitoring of streams affecting environment.

  18. Post-synthesis annealing effects on SrGa2Se4:Eu2+ phosphors with peak emission wavelength in the green gap

    Science.gov (United States)

    Zhu, Yiting; Dutta, Partha; Narendran, Nadarajah

    2010-08-01

    A high-quality white light source requires high luminous efficacy (lumens per input watt). Theoretically, in the "greenyellow" spectral region (with a peak wavelength at around 555 nm), the luminous efficiency (lumens per radiant watt) reaches a maximum based on the luminous efficiency function, V(λ), and can potentially generate high luminous efficacy. Unfortunately, the light-emitting diode (LED) suffers from low external quantum efficiency in the "greenyellow" region, thereby lowering the luminous efficacy value. Researchers have sought solutions such as nonpolar or semipolar InGaN/GaN LEDs. An alternative to generating green light is to use phosphor down-conversion by exciting a green emission phosphor with a near-UV or blue LED of higher external quantum efficiency. In this study, a SrGa2Se4:Eu2+ phosphor with peak emission wavelength at 555 nm was initially synthesized and followed by a systematic study of the post-synthesis annealing. The purpose of this study was to investigate how post-synthesis annealing conditions, including annealing temperature, annealing duration, and annealing ambient atmosphere, can affect phosphor performance. The phosphor performance was characterized in terms of external quantum efficiency and emission properties. How the external quantum efficiency of the phosphor can be further improved is also discussed.

  19. Atlas of uranium emission intensities in a hollow cathode discharge

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, B.A.; Keller, R.A.; Engleman, R. Jr.

    1980-07-01

    The uranium emission spectrum from a hollow cathode discharge is displayed from 11,000 to 26,000 cm/sup -1/. This atlas lists 4928 spectral lines of uranium; 3949 are classified to the neutral spectrum and 431 are classified to the singly ionized spectrum. Listed wavenumbers are accurate to +-0.003 cm/sup -1/ and the listed relative intensities to +-8%. The richness of the spectrum makes this atlas useful for wavenumber calibration of lasers, spectrographs, and monochromators to an accuracy of 1 part in 10/sup 7/. This atlas is also useful as a guide to the uranium spectrum, and relative oscillator strengths (gf values) can be calculated from the intensities to a precision of +-20%.

  20. Classification of peaked spectrum sources by using neural networks

    Science.gov (United States)

    Vera, R. J. C.; Tornikoski, M.; Lähteenmäki, A.

    2017-07-01

    Compact steep-spectrum sources (CSS), high frequency peakers (HFP), and gigahertz-peaked spectrum sources (GPS) are compact radio sources with an intense emission (O'Dea 1998, and references therein). Morphological studies, dense gas analyses, and surveys suggesting the absence of a halo diffusion emission, suggest the idea that peaked spectrum sources (PSS) are young AGN (see, Fanti et al. 1995; Readhead et al. 1996; Stanghellini et al. 1997; Bicknell et al. 1997). Previously, Torniainen et al. (2008) carried out a study of GPS sources, finding that those sources do not follow a distinct morphological classification. In addition, they found that many blazars in a flaring state are misclassified as GPS sources (Torniainen et al. 2005). These findings compromised the simple vision of the g alaxy-quasar dualism, and the amount of genuine GPS sources. For this reason, we endeavour a new classification of 363 sources with the aim to find new insights about their spectral properties using neural networks. Through clustering methods, we have grouped galaxies that present a set of similar physical properties. In total, 18 physical variables were used for this purpose. In particular, we used Multi-dimensional Scaling (MDS) and t-distributed Stochastic Neighbour Embedding (t-SNE) analyses. Those analyses proved to be robust for analysing data of the order of hundreds of data. From our analyses, we were unable to find a clear classification for PSS. Moreover, new galaxies presented a flat spectra emission, or high variability in the radio emission, compromising their classification as genuine PSS.

  1. The spectrum and morphology of the Fermi bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, M.; Buehler, R. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Albert, A.; Blandford, R. D.; Bloom, E. D.; Bottacini, E.; Caliandro, G. A.; Cameron, R. A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Atwood, W. B. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Baldini, L.; Bellazzini, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d' Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Bastieri, D.; Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bissaldi, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, and Università di Trieste, I-34127 Trieste (Italy); Brandt, T. J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bregeon, J. [Laboratoire Univers et Particules de Montpellier, Université Montpellier 2, CNRS/IN2P3, Montpellier (France); Bruel, P. [Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, Palaiseau (France); Caragiulo, M., E-mail: afrancko@slac.stanford.edu, E-mail: malyshev@stanford.edu, E-mail: vahep@stanford.edu [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari (Italy); and others

    2014-09-20

    The Fermi bubbles are two large structures in the gamma-ray sky extending to 55° above and below the Galactic center. We analyze 50 months of Fermi Large Area Telescope data between 100 MeV and 500 GeV above 10° in Galactic latitude to derive the spectrum and morphology of the Fermi bubbles. We thoroughly explore the systematic uncertainties that arise when modeling the Galactic diffuse emission through two separate approaches. The gamma-ray spectrum is well described by either a log parabola or a power law with an exponential cutoff. We exclude a simple power law with more than 7σ significance. The power law with an exponential cutoff has an index of 1.9 ± 0.2 and a cutoff energy of 110 ± 50 GeV. We find that the gamma-ray luminosity of the bubbles is 4.4{sub −0.9}{sup +2.4}×10{sup 37} erg s{sup –1}. We confirm a significant enhancement of gamma-ray emission in the southeastern part of the bubbles, but we do not find significant evidence for a jet. No significant variation of the spectrum across the bubbles is detected. The width of the boundary of the bubbles is estimated to be 3.4{sub −2.6}{sup +3.7} deg. Both inverse Compton (IC) models and hadronic models including IC emission from secondary leptons fit the gamma-ray data well. In the IC scenario, synchrotron emission from the same population of electrons can also explain the WMAP and Planck microwave haze with a magnetic field between 5 and 20 μG.

  2. The Spectrum and Morphology of the Fermi Bubbles

    Science.gov (United States)

    Ackermann, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazini, R.; Bissaldi, E.; Brandt, T. J.; Ferrara, E. C.; Guiriec, S.; Harding, A. K.; Hayes, E.; Kocevski, D.; McEnery, J. E.; Nemmen, R.; Perkins, J. S.; Troja, E.

    2014-01-01

    The Fermi bubbles are two large structures in the gamma-ray sky extending to 55 deg above and below the Galactic center. We analyze 50 months of Fermi Large Area Telescope data between 100 MeV and 500 GeV above 10 deg in Galactic latitude to derive the spectrum and morphology of the Fermi bubbles. We thoroughly explore the systematic uncertainties that arise when modeling the Galactic diffuse emission through two separate approaches. The gamma-ray spectrum is well described by either a log parabola or a power law with an exponential cutoff. We exclude a simple power law with more than 7 sigma significance. The power law with an exponential cutoff has an index of 1.90+/-0.2 and a cutoff energy of 110+/- 50 GeV. We find that the gamma-ray luminosity of the bubbles is 4.4(+)2.4(-0.9 ) 10(exp 37) erg s-1. We confirm a significant enhancement of gamma-ray emission in the south-eastern part of the bubbles, but we do not find significant evidence for a jet. No significant variation of the spectrum across the bubbles is detected. The width of the boundary of the bubbles is estimated to be 3.4(+)3.7(-)2.6 deg. Both inverse Compton (IC) models and hadronic models including IC emission from secondary leptons t the gamma-ray data well. In the IC scenario, the synchrotron emission from the same population of electrons can also explain the WMAP and Planck microwave haze with a magnetic field between 5 and 20 micro-G.

  3. High latitude electromagnetic plasma wave emissions

    Science.gov (United States)

    Gurnett, D. A.

    1983-01-01

    The principal types of electromagnetic plasma wave emission produced in the high latitude auroral regions are reviewed. Three types of radiation are described: auroral kilometric radiation, auroral hiss, and Z mode radiation. Auroral kilometric radiation is a very intense radio emission generated in the free space R-X mode by electrons associated with the formation of discrete auroral arcs in the local evening. Theories suggest that this radiation is an electron cyclotron resonance instability driven by an enhanced loss cone in the auroral acceleration region at altitudes of about 1 to 2 R sub E. Auroral hiss is a somewhat weaker whistler mode emission generated by low energy (100 eV to 10 keV) auroral electrons. The auroral hiss usually has a V shaped frequency time spectrum caused by a freqency dependent beaming of the whistler mode into a conical beam directed upward or downward along the magnetic field.

  4. Luminescent solar concentrator improvement by stimulated emission

    Science.gov (United States)

    Kaysir, Md Rejvi; Fleming, Simon; MacQueen, Rowan W.; Schmidt, Timothy W.; Argyros, Alexander

    2015-12-01

    Luminescent solar concentrators (LSCs) offer the prospect of reducing the cost of solar energy, and are a promising candidate for building integrated photovoltaic (PV) structures. However, the realization of commercially viable efficiency of LSCs is currently hindered by reabsorption losses. In this work, a method is introduced for reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire length of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption, and directed by the seed laser towards a small target PV cell. A mathematical model of such a system is presented which identifies different physical parameters responsible for the power conversion efficiency and gives the net effective output power.

  5. Luminescent solar concentrators utilizing stimulated emission.

    Science.gov (United States)

    Kaysir, Md Rejvi; Fleming, Simon; MacQueen, Rowan W; Schmidt, Timothy W; Argyros, Alexander

    2016-03-21

    Luminescent solar concentrators (LSCs) are an emerging technology that aims primarily to reduce the cost of solar energy, with great potential for building integrated photovoltaic (PV) structures. However, realizing LSCs with commercially viable efficiency is currently hindered by reabsorption losses. Here, we introduce an approach to reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire area of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption to allow net gain in the system, and directed towards a small PV cell. A mathematical model, taking into account thermodynamic considerations, of such a system is presented which identifies key parameters and allows evaluation in terms of net effective output power.

  6. Quantum Corrected Non-Thermal Radiation Spectrum from the Tunnelling Mechanism

    Directory of Open Access Journals (Sweden)

    Subenoy Chakraborty

    2015-06-01

    Full Text Available The tunnelling mechanism is today considered a popular and widely used method in describing Hawking radiation. However, in relation to black hole (BH emission, this mechanism is mostly used to obtain the Hawking temperature by comparing the probability of emission of an outgoing particle with the Boltzmann factor. On the other hand, Banerjee and Majhi reformulated the tunnelling framework deriving a black body spectrum through the density matrix for the outgoing modes for both the Bose-Einstein distribution and the Fermi-Dirac distribution. In contrast, Parikh and Wilczek introduced a correction term performing an exact calculation of the action for a tunnelling spherically symmetric particle and, as a result, the probability of emission of an outgoing particle corresponds to a non-strictly thermal radiation spectrum. Recently, one of us (C. Corda introduced a BH effective state and was able to obtain a non-strictly black body spectrum from the tunnelling mechanism corresponding to the probability of emission of an outgoing particle found by Parikh and Wilczek. The present work introduces the quantum corrected effective temperature and the corresponding quantum corrected effective metric is written using Hawking’s periodicity arguments. Thus, we obtain further corrections to the non-strictly thermal BH radiation spectrum as the final distributions take into account both the BH dynamical geometry during the emission of the particle and the quantum corrections to the semiclassical Hawking temperature.

  7. Novel pricing model for spectrum leasing in secondary spectrum market

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; XU Xing-kun; XU Wen-jun; HE Zhi-qiang; LIN Jia-ru

    2010-01-01

    According to the property rights model of cognitive radio,primary users who own the spectral resource have the right to lease or trade part of it to secondary users in exchange for appropriate profit. In this paper,an implementation of this framework is investigated,where a primary link can lease the owned spectrum to secondary nodes in exchange for cooperation (relaying). A novel pricing model is proposed that enables the trading between spectrum and cooperation. Based on the demand of secondary nodes,the primary link attempts to maximize its quality of service (QoS) by setting the price of spectrum. Taking the price asked by primary link,the secondary nodes aim to obtain most profits by deciding the amount of spectrum to buy and then pay for it by cooperative transmission. The investigated model is conveniently cast in the framework of seller/buyer (Stackelberg) games. Analysis and numerical results show that our pricing model is effective and practical for spectrum leasing based on trading spectral resource for cooperation.

  8. Ammonia emissions in Europe

    DEFF Research Database (Denmark)

    Jacobsen, Brian H.

    2012-01-01

    The NEC (National Emission Ceiling) directive has set targets for the 2010 ammonia emissions from a number of European countries. The target will be reached by most EU-countries and the total emission for EU-27 has been reduced by 22% from 1990 to 2007. Denmark is one of the countries with the la......The NEC (National Emission Ceiling) directive has set targets for the 2010 ammonia emissions from a number of European countries. The target will be reached by most EU-countries and the total emission for EU-27 has been reduced by 22% from 1990 to 2007. Denmark is one of the countries...

  9. Investigation of RF Emissions from Two Beams Interacting with an Electric Field Dominated Plasma

    Science.gov (United States)

    1986-05-15

    emission spectrum is not random in character or due to inadequate video filtering; retracing of the spectrum with ^ a manual scan shows that the peaks are...Electrical Engineering, UTK. "A Study of Tokamak Confinement Time Scaling Based on MHD Current Penetration". A derivation of an alcator -like

  10. Analysis of (K^-,K^+) inclusive spectrum with semiclassical distorted wave model

    CERN Document Server

    Hashimoto, S; Kohno, M; Ogata, K

    2006-01-01

    The inclusive K^+ momentum spectrum in the 12C(K^-,K^+) reaction is calculated by the semiclassical distorted wave (SCDW) model, including the transition to the \\Xi^- bound state. The calculated spectra with the strength of the \\Xi^--nucleus potential -50, -20, and +10 MeV are compared with the experimental data measured at KEK with p_{K^-}=1.65 GeV/c. The shape of the spectrum is reproduced by the calculation. Though the inclusive spectrum changes systematically depending on the potential strength, it is not possible to obtain a constraint on the potential from the present data. The calculated spectrum is found to have strong emission-angle dependence. We also investigate the incident K^- momentum dependence of the spectrum to see the effect of the Fermi motion of the target nucleons which is explicitly treated in the SCDW method.

  11. Water, Methane, and Carbon Dioxide Present in the Dayside Spectrum of the Exoplanet HD 209458b

    CERN Document Server

    Swain, M; Vasisht, G; Deroo, P; Griffith, C; Bouwman, J; Chen, Pin; Yung, Y; Burrows, A; Brown, L R; Matthews, J; Roe, J F; Kuschnig, R; Angerhausen, D

    2009-01-01

    Using the NICMOS instrument on the Hubble Space Telescope, we have measured the dayside spectrum of HD 209458b between 1.5--2.5 microns. The emergent spectrum is dominated by features due to the presence of methane (CH4) and water vapor (H2O), with smaller contributions from carbon dioxide (CO2). Combining this near-infrared spectrum with existing mid-infrared measurements shows the existence of a temperature inversion and confirms the interpretation of previous photometry measurements. We find a family of plausible solutions for the molecular abundance and detailed temperature profile. Observationally resolving the ambiguity between abundance and temperature requires either (1) improved wavelength coverage or spectral resolution of the dayside emission spectrum, or (2) a transmission spectrum where abundance determinations are less sensitive to the temperature structure.

  12. The Spectrum and Laplacian Spectrum of the Dice Lattice

    Science.gov (United States)

    Li, Shuli; Yan, Weigen; Tian, Tao

    2016-07-01

    The dice lattice is the dual lattice of kagomé lattice. Many physical properties on the dice lattice have been studied by physicists, such as Ising model, Glassy dynamics of Josephson arrays, and Lattice Green's function. In this paper, we derive the spectrum and Laplacian spectrum of the dice lattice with toroidal boundary condition. In addition, we apply our results to obtain the formulae of the number of spanning trees, the Kirchhoff index, and the energy of the dice lattice with toroidal boundary condition.

  13. Non-strictly black body spectrum from the tunnelling mechanism

    CERN Document Server

    Corda, Christian

    2013-01-01

    A modern and largely used approach to obtain Hawking radiation is the tunnelling mechanism. However, in various papers in the literature, the analysis concerned almost only to obtain the Hawking temperature through a comparison of the probability of emission of an outgoing particle with the Boltzmann factor. In a interesting and well written paper, Banerjee and Majhi improved the approach, by explicitly finding a black body spectrum associated with black holes. On the other hand, this result, which has been obtained by using a reformulation of the tunnelling mechanism, is in contrast which the remarkable result by Parikh and Wilczek, that, indeed, found a probability of emission which is compatible with a non-strictly thermal spectrum. By using our recent introduction of an effective state for a black hole, here we solve such a contradiction, through a slight modification of the analysis by Banerjee and Majhi. The final result will be a non-strictly black body spectrum from the tunnelling mechanism. We also s...

  14. The Biokinetic Spectrum for Temperature.

    Directory of Open Access Journals (Sweden)

    Ross Corkrey

    Full Text Available We identify and describe the distribution of temperature-dependent specific growth rates for life on Earth, which we term the biokinetic spectrum for temperature. The spectrum has the potential to provide for more robust modeling in thermal ecology since any conclusions derived from it will be based on observed data rather than using theoretical assumptions. It may also provide constraints for systems biology model predictions and provide insights in physiology. The spectrum has a Δ-shape with a sharp peak at around 42°C. At higher temperatures up to 60°C there was a gap of attenuated growth rates. We found another peak at 67°C and a steady decline in maximum rates thereafter. By using Bayesian quantile regression to summarise and explore the data we were able to conclude that the gap represented an actual biological transition between mesophiles and thermophiles that we term the Mesophile-Thermophile Gap (MTG. We have not identified any organism that grows above the maximum rate of the spectrum. We used a thermodynamic model to recover the Δ-shape, suggesting that the growth rate limits arise from a trade-off between activity and stability of proteins. The spectrum provides underpinning principles that will find utility in models concerned with the thermal responses of biological processes.

  15. Emissions Modeling Clearinghouse

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Emissions Modeling Clearinghouse (EMCH) supports and promotes emissions modeling activities both internal and external to the EPA. Through this site, the EPA...

  16. Walkable dual emissions

    National Research Council Canada - National Science Library

    Xu, Hai-Bing; Jiao, Peng-Chong; Kang, Bin; Deng, Jian-Guo; Zhang, Yan

    2013-01-01

    Walkable dual emissions, in which the emission bands of the walker reversibly cross or leave those of the stationary ones depending on temperature and concentration, have been demonstrated in cyclic...

  17. National Emission Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The National Emission Inventory contains measured, modeled, and estimated data for emissions of all known source categories in the US (stationary sources, fires,...

  18. World Emission RETRO ANTHRO

    Data.gov (United States)

    Washington University St Louis — Anthropogenic and vegetation fire emissions data were generated monthly covering a period of 1960 to 2000. Anthropogenic emissions in the RETRO inventory are derived...

  19. Emissions & Measurements - Black Carbon

    Science.gov (United States)

    Emissions and Measurement (EM) research activities performed within the National Risk Management Research Lab NRMRL) of EPA's Office of Research and Development (ORD) support measurement and laboratory analysis approaches to accurately characterize source emissions, and near sour...

  20. What Is Emissions Trading?

    Science.gov (United States)

    Learn the basics about how emissions trading uses a market-based policy tool used to control large amounts of pollution emissions from a group of sources in order to protect human health and the environment.

  1. National Emission Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The National Emission Inventory contains measured, modeled, and estimated data for emissions of all known source categories in the US (stationary sources, fires,...

  2. Recognizing blue emission in artificial aurora

    Science.gov (United States)

    Holma, H.; Kaila, K.; Jussila, J.; Kosch, M.; Rietveld, M.

    On 12th November 2001, during the EISCAT UK/GE artificial aurora campaign, the optical group of University of Oulu performed the optical measurements at the EISCAT site in Ramfjordmoen. That campaign was the first successful attempt of inducing blue emission in artificial aurora at high latitudes. Optical instruments were monitoring emis-sions and they included a photometer, a real speed TV camera and a digital camera. The emissions measured by the photometer are 557.7 nm (OI), 630.0 nm (OI) and 427.8 nm (N2+). The threshold energies for these emissions to arise are 2 eV, 4 eV and 19 eV, re-spectively. In the natural aurora the blue emission at around 427 nm is always highly dominated by N2+ 1NG (0,1) rotational band. However, there are two weak emissions lying under this strong emission. These bands are N2 VK(4,15) (threshold energy 6 eV) and N2 2P(1,5) (threshold 11 eV). These energies are remarkably lower and could obviously have stronger intensity in the spectrum of artificial aurora than in natural aurora that is domi-nated by harder electron bombardment. The auroral photometer of the university of Oulu has been designed for investigating natural aurora, which results some limitations regarding the artificial aurora, to the data that has been obtained. The photometer was equipped with two channels measuring two close wavelength bands around 427 nm. These channels were aimed to be used to de-termine rotational temperature from the ratio of the intensities through the channels. Now they will be used to estimate the intensities of the three overlapping emission bands instead.

  3. Can the tinnitus spectrum identify tinnitus subgroups?

    NARCIS (Netherlands)

    Heijneman, Karin M.; de Kleine, Emile; Wiersinga-Post, Esther; van Dijk, Pim

    2013-01-01

    The tinnitus spectrum is a psycho-acoustic metric of tinnitus. Previous work found a tight relation between the spectrum and the tone audiogram. This suggests that the spectrum and the audiogram provide essentially the same information, and the added value of the spectrum is limited. In order to tes

  4. Density Spectrums from Kinetic Inflations

    CERN Document Server

    Hwang, J

    1996-01-01

    The pole-like accelerated expansion stages purely driven by the coupling between the gravity and the dilaton field without referring to the potential term can be realized in a class of generalized gravity theories. We consider three such scenarios based on the scalar-tensor gravity, the induced gravity and the string theory. Quantum fluctuations during the expansion stages (including more general situations) can be derived in exact analytic forms. Assuming that the pole-like acceleration stage provides a viable inflation scenario in the early universe we derive the generated classical density spectrums. The generated classical density field shows a generic tilted spectrum with $n \\simeq 4$ which differs from the observed spectrum supporting $n \\simeq 1$.

  5. The Sun's Photospheric Convection Spectrum

    CERN Document Server

    Hathaway, David H; Norton, Aimee A; Kitiashvili, Irina

    2015-01-01

    Spectra of the cellular photospheric flows are determined from full-disk Doppler velocity observations acquired by the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO) spacecraft. Three different analysis methods are used to separately determine spectral coefficients representing the poloidal flows, the toroidal flows, and the radial flows. The amplitudes of these spectral coefficients are constrained by simulated data analyzed with the same procedures as the HMI data. We find that the total velocity spectrum rises smoothly to a peak at a wavenumber of about 120 (wavelength of about 35 Mm), which is typical of supergranules. The spectrum levels off out to wavenumbers of about 400, and then rises again to a peak at a wavenumber of about 3500 (wavelength of about 1200 km), which is typical of granules. The velocity spectrum is dominated by the poloidal flow component (horizontal flows with divergence but no curl) at wavenumbers above 30. The toroidal flow component (hori...

  6. The high energy spectrum of 3C 273

    CERN Document Server

    Esposito, V; Jean, P; Tramacere, A; Türler, M; Lähteenmäki, A; Tornikoski, M

    2015-01-01

    Aims. The high energy spectrum of 3C 273 is usually understood in terms of inverse-Compton emission in a relativistic leptonic jet. This model predicts variability patterns and delays that could be tested with simultaneous observations from the radio to the GeV range. Methods. The instruments IBIS, SPI, JEM-X on board INTEGRAL, PCA on board RXTE, and LAT on board Fermi have enough sensitivity to follow the spectral variability of 3C 273 from the keV to the GeV. We looked for correlations between the different energy bands, including radio data at 37 GHz collected at the Mets\\"ahovi Radio Observatory and built quasi-simultaneous multiwavelength spectra in the high energy domain when the source is flaring either in the X-rays or in the {\\gamma} rays. Results. Both temporal and spectral analysis suggest a two-component model to explain the complete high energy spectrum. X-ray emission is likely dominated by a Seyfert-like component while the {\\gamma}-ray emission is dominated by a blazar-like component produced ...

  7. Compressive Wideband Spectrum Sensing for Fixed Frequency Spectrum Allocation

    CERN Document Server

    Liu, Yipeng

    2010-01-01

    Too high sampling rate is the bottleneck to wideband spectrum sensing for cognitive radio (CR). As the survey shows that the sensed signal has a sparse representation in frequency domain in the mass, compressed sensing (CS) can be used to transfer the sampling burden to the digital signal processor. An analog to information converter (AIC) can randomly sample the received signal with sub-Nyquist rate to obtained the random measurements. Considering that the static frequency spectrum allocation of primary radios means the bounds between different primary radios is known in advance, here we incorporate information of the spectrum boundaries between different primary user as a priori information to obtain a mixed l2/l1 norm denoising operator (MNDO). In the MNDO, the estimated power spectrum density (PSD) vector is divided into block sections with bounds corresponding different allocated primary radios. Different from previous standard l1-norm constraint on the whole PSD vector, a sum of the l2 norm of each sect...

  8. Luminosity Spectrum Reconstruction at Linear Colliders

    CERN Document Server

    Poss, Stéphane

    2014-01-01

    A good knowledge of the luminosity spectrum is mandatory for many measurements at future e+e- colliders. As the beam-parameters determining the luminosity spectrum cannot be measured precisely, the luminosity spectrum has to be measured through a gauge process with the detector. The measured distributions, used to reconstruct the spectrum, depend on Initial State Radiation, cross-section, and Final State Radiation. To extract the basic luminosity spectrum, a parametric model of the luminosity spectrum is created, in this case the spectrum at the 3 TeV Compact Linear Collider (CLIC). The model is used within a reweighting technique to extract the luminosity spectrum from measured Bhabha event observables, taking all relevant effects into account. The centre-of-mass energy spectrum is reconstructed within 5% over the full validity range of the model. The reconstructed spectrum does not result in a significant bias or systematic uncertainty in the exemplary physics benchmark process of smuon pair production.

  9. Dynamic spectrum auction in wireless communication

    CERN Document Server

    Chen, Yanjiao

    2015-01-01

    This brief explores current research on dynamic spectrum auctions, focusing on fundamental auction theory, characteristics of the spectrum market, spectrum auction architecture and possible auction mechanisms. The brief explains how dynamic spectrum auctions, which enable new users to gain spectrum access and existing spectrum owners to obtain financial benefits, can greatly improve spectrum efficiency by resolving the artificial spectrum shortage. It examines why operators and users face significant challenges due to specialty of the spectrum market and the related requirements imposed on the auction mechanism design. Concise and up-to-date, Dynamic Spectrum Auction in Wireless Communication is designed for researchers and professionals in computer science or electrical engineering. Students studying networking will also find this brief a valuable resource.

  10. Spread Spectrum Mobile Radio Communications.

    Science.gov (United States)

    1984-09-15

    seconds, yielding Z Y a =XMZ m M .-m The sequence of operacions is illustrated by the matrices of figures ’--3- and 1-3b. Each matrix is either a...sequence of K-bit numbers (code word, address, detection matrix) or a frequency-time spectrogram (traasmit spectrum, receive spectrum). The matrices pertain...and a reduced rank-sum receiver. In figure 3-1, we show the operation of a MRSR by means of matrices . 3-1 Reduced Rank-Sum Receiver With the values of

  11. Autism Spectrum Disorders in Iran

    OpenAIRE

    Mohammadi, Mohammad Reza; Salmanian, Maryam; Akhondzadeh, Shahin

    2011-01-01

    How to Cite this Article: Mohammadi MR, Salmanian M, Akhondzadeh Sh. Autism Spectrum Disorders in Iran. Iranian Journal of Child Neurology2011;5(4):1-9.ObjectiveAutistic disorder, Asperger syndrome, and PDD-Not Otherwise Specified are subsets of autism spectrum disorders (ASDs), which are characterized by impairments in social communication and stereotyped behavior. This article reviews the prevalence, etiology, diagnosis, and treatment of ASDs in Iran.Materials & MethodsWe searched PubMe...

  12. Nebular Continuum and Line Emission in Stellar Population Synthesis Models

    Science.gov (United States)

    Byler, Nell; Dalcanton, Julianne J.; Conroy, Charlie; Johnson, Benjamin D.

    2017-05-01

    Accounting for nebular emission when modeling galaxy spectral energy distributions (SEDs) is important, as both line and continuum emissions can contribute significantly to the total observed flux. In this work, we present a new nebular emission model integrated within the Flexible Stellar Population Synthesis code that computes the line and continuum emission for complex stellar populations using the photoionization code Cloudy. The self-consistent coupling of the nebular emission to the matched ionizing spectrum produces emission line intensities that correctly scale with the stellar population as a function of age and metallicity. This more complete model of galaxy SEDs will improve estimates of global gas properties derived with diagnostic diagrams, star formation rates based on Hα, and physical properties derived from broadband photometry. Our models agree well with results from other photoionization models and are able to reproduce observed emission from H ii regions and star-forming galaxies. Our models show improved agreement with the observed H ii regions in the Ne iii/O ii plane and show satisfactory agreement with He ii emission from z = 2 galaxies, when including rotating stellar models. Models including post-asymptotic giant branch stars are able to reproduce line ratios consistent with low-ionization emission regions. The models are integrated into current versions of FSPS and include self-consistent nebular emission predictions for MIST and Padova+Geneva evolutionary tracks.

  13. Extended Anomalous Foreground Emission in the WMAP 3-Year Data

    CERN Document Server

    Dobler, Gregory

    2007-01-01

    We study the spectral and morphological characteristics of the diffuse Galactic emission in the WMAP temperature data using a template-based multi-linear regression, and obtain the following results. 1. We confirm previous observations of a bump in the dust-correlated spectrum, consistent with the Draine & Lazarian spinning dust model. 2. We also confirm the "haze" signal in the inner Galaxy, and argue that it does not follow a free-free spectrum as first thought, but instead is synchrotron emission from a hard electron cosmic-ray population. 3. In a departure from previous work, we allow the spectrum of Halpha-correlated emission (which is used to trace the free-free component) to float in the fit, and find that it does not follow the expected free-free spectrum. Instead there is a bump near 50 GHz, modifying the spectrum at the 20% level, which we speculate is caused by spinning dust in the warm ionized medium. 4. The derived cross-correlation spectra are not sensitive to the map zero points, but are se...

  14. Minimum ionizing particle detection by secondary electron emission

    Energy Technology Data Exchange (ETDEWEB)

    Faivre, J.C.; Fanet, H.; Garin, A.; Robert, J.P.; Rouger, M.; Saudinos, J.

    1977-02-01

    The use of secondary electron emission to detect high energy particles is investigated. Low density KCl layers have been tested to detect MeV electrons, 400-750 MeV protons and high energy deuterons. The efficiency and the secondary electron spectrum are presented. The results justify the use of low-density KCl layer to detect minimum ionizing particles.

  15. Spontaneous Emission Enhancement at Finite-length Metal

    DEFF Research Database (Denmark)

    Filonenko, K.; Willatzen, Morten; Bordo, V.

    2013-01-01

    We study spontaneous emission enhancement of a two-level atomic emitter placed in a dielectric medium near a finite-length cylindrical metal nanowire. We calculate the dependence of the Purcell factor and the normalized decay rate to a continuous spectrum on the nanowire radius for several emitter...

  16. Kinerja Spectrum Sensing Dengan Metode Cyclostationary Feature Detector Pada Radio Kognitif

    Directory of Open Access Journals (Sweden)

    HENDRY CAHYO

    2017-06-01

    Full Text Available   Abstrak Perkembangan dalam dunia telekomunikasi nirkabel terutama spektrum frekuensi adalah hal yang perlu mendapatkan perhatian penting. Spektrum frekuensi merupakan sumber daya yang terbatas, penggunaannya harus dilakukan secara efisien dan se-maksimal mungkin. Penelitian ini membahas teknik spectrum sensing pada radio kognitif untuk menghadapi masalah keterbatasan penggunaan spektrum frekuensi. Radio kognitif merupakan sistem radio cerdas yang bisa mengatur parameternya seperti frekuensi kerja, daya pancar, dan skema modulasi secara optimal dalam melakukan proses komunikasi. Spectrum sensing merupakan teknik untuk memaksimalkan penggunaan spektrum frekuensi. Penelitian ini membandingkan kinerja metode cyclostationary feature detection dan metode energy detection pada teknik spectrum sensing menggunakan software matlab sehingga dapat diketahui bahwa kinerja cyclostationary feature detection untuk nilai Pd = 0,85 lebih handal sebesar 0,2 untuk fungsi probability of false dan lebih handal sebesar 2 dB untuk fungsi signal to noise ratio daripada energy detection. Kata kunci: radio kognitif, spectrum sensing, cyclostationary feature detection, energy detection, probability of false alarm.   Abstract Developments in the world of wireless telecommunications specially frequency spectrum is an important thing to get attention. Frequency spectrum is afinite resource, its use must be efficiently and as maximum as possible. This study discuss the technique of spectrum sensing in cognitive radio to faces the problem using restrictiveness of frequency spectrum. Cognitive radio is a smart radio system that can adjust its parameters like work frequency, emission power, and modulation scheme are optimal in the communication process. Spectrum sensing is a technique to maximize the use of the frequency spectrum. This study compared performance of cyclostationary feature detection methodh with energy detection methodh in spectrum sensing technique using

  17. The Ultraviolet Spectrum of η Carinae: Investigation of the Ejecta Absorption

    Science.gov (United States)

    Nielsen, K. E.; Gull, T. R.; Vieira Kober, G.

    2005-03-01

    We have investigated the far- through mid-UV (1150-2360 Å) spectrum of η Carinae during the late stages of its broad maximum using the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) moderate dispersion echelle modes. The η Car spectrum is a mixture of absorption and emission lines from the surrounding nebula superimposed on broad stellar wind features. This paper provides a description of the observed spectrum including the wind features, the interstellar absorption, and the emission spectrum from the surrounding nebula, but with the emphasis on the absorption spectrum formed in the foreground ejecta. The ejecta absorption spectrum has a complicated velocity structure in which two velocity structures, at -146 and -513 km s-1, are easily distinguished. These two velocity components, formed in different regions of the η Car nebula, have in an earlier analysis been identified and demonstrated to have very different spectral characteristics. The slower velocity component is time variable over the spectroscopic period and is characterized by spectral lines from mainly singly ionized iron-peak elements, while the faster one shows transitions from neutral and singly ionized elements in addition to molecular lines from the hydrogen Lyman bands. The high-velocity H2 lines dominate great parts of the spectrum with over 800 identified transitions from energy levels up to 30,000 cm-1. The STIS MAMA data provide the tool for spatial investigations of the central parts of η Car. H I Lyα pumped and semiforbidden emission lines are observed to be formed east of the central source toward Weigelt blobs B and C, located up to 0.2" from the central source. The complete spectrum, with nebular and interstellar line identifications, is available in the electronic edition of the paper. Laboratory for Astronomy and Solar Physics, Code 681, Goddard Space Flight Center, Greenbelt, MD 20771.

  18. Flare emission from Sagittarius A*

    CERN Document Server

    Eckart, A; Vogel, S N; Teuben, P; Morris, M R; Baganoff, F; Dexter, J; Schoedel, R; Witzel, G; Valencia-S., M; Karas, V; Kunneriath, D; Bremer, M; Straubmeier, C; Moser, L; Sabha, N; Buchholz, R; Zamaninasab, M; Muzic, K; Moultaka, J; Zensus, J A

    2012-01-01

    Based on Bremer et al. (2011) and Eckart et al. (2012) we report on simultaneous observations and modeling of the millimeter, near-infrared, and X-ray flare emission of the source Sagittarius A* (SgrA*) associated with the super-massive black hole at the Galactic Center. We study physical processes giving rise to the variable emission of SgrA* from the radio to the X-ray domain. To explain the statistics of the observed variability of the (sub-)mm spectrum of SgrA*, we use a sample of simultaneous NIR/X-ray flare peaks and model the flares using a synchrotron and SSC mechanism. The observations reveal flaring activity in all wavelength bands that can be modeled as the signal from adiabatically expanding synchrotron self-Compton (SSC) components. The model parameters suggest that either the adiabatically expanding source components have a bulk motion larger than v_exp or the expanding material contributes to a corona or disk, confined to the immediate surroundings of SgrA*. For the bulk of the synchrotron and ...

  19. The TeV spectrum of H1426+428

    CERN Document Server

    Petry, D; Bradbury, S M; Buckley, J H; Carter-Lewis, D A; Cui, W; Duke, C; De la Calle-Perez, I; Falcone, A D; Fegan, D J; Fegan, S J; Finley, J P; Gaidos, J A; Gibbs, K; Gammell, S; Hall, J; Hall, T A; Hillas, A M; Holder, J; Horan, D; Jordan, M; Kertzman, M P; Kieda, D B; Kildea, J; Knapp, J; Kosack, K; Krennrich, F; Le Bohec, S; Moriarty, P; Müller, D; Nagai, T N; Ong, R; Page, M; Pallassini, R; Power-Mooney, B; Quinn, J; Reay, N W; Reynolds, P T; Rose, H J; Schroedter, M; Sembroski, G H; Sidwell, R; Stanton, N; Swordy, S P; Vasilev, V; Wakely, S P; Walker, G; Weekes, T C

    2002-01-01

    The BL Lac object H1426+428 was recently detected as a high energy gamma-ray source by the VERITAS collaboration (Horan et al. 2002). We have reanalyzed the 2001 portion of the data used in the detection in order to examine the spectrum of H1426+428 above 250 GeV. We find that the time-averaged spectrum agrees with a power law of the shape dF/dE = 10^(-7.31 +- 0.15(stat) +- 0.16(syst)) x E^(-3.50 +- 0.35(stat) +- 0.05(syst)) m^(-2)s^(-1)TeV^(-1) The statistical evidence from our data for emission above 2.5 TeV is 2.6 sigma. With 95% c.l., the integral flux of H1426+428 above 2.5 TeV is larger than 3% of the corresponding flux from the Crab Nebula. The spectrum is consistent with the (non-contemporaneous) measurement by Aharonian et al. (2002) both in shape and in normalization. Below 800 GeV, the data clearly favours a spectrum steeper than that of any other TeV Blazar observed so far indicating a difference in the processes involved either at the source or in the intervening space.

  20. Giant many-body effects in liquid ammonia absorption spectrum

    Science.gov (United States)

    Ziaei, Vafa; Bredow, Thomas

    2016-11-01

    In the present work, we accurately calculate the absorption spectrum of liquid ammonia up to 13 eV using many-body perturbation approach. The electronic bandgap of liquid NH3 is perfectly described as the combination of density functional theory, Coulomb-hole screened exchange, and G0W0 approximation to the electronic self-energy, yielding a direct gap (Γ → Γ) of 7.71 eV, fully consistent with the experimentally measured gap from photo-emission spectroscopy. With respect to the NH3 optical properties, the entire spectrum in particular the low lying first absorption band is extremely affected by electron-hole interactions, leading to a fundamental redistribution of spectral weights of the independent-particle spectrum. Three well separated but broad main peaks are identified at 7.0, 9.8, and 11.8 eV with steadily increasing intensities in excellent agreement with the experimental data. Furthermore, we observe a giant net blue-shift of the first absorption peak of about 1.4 eV from gaseous to liquid phase as the direct consequence of many-body effects, allowing the associated liquid ammonia absorption band exciton to delocalize and feel more effectively the repulsion effects imposed by the surrounding solvent shells. Further, the spectrum is insensitive to the coupling of resonant and anti-resonant contributions. Concerning electronic response structure of liquid NH3, it is most sensitive to excitations at energies lower than its electronic gap.

  1. The 44Ti-powered spectrum of SN 1987A

    CERN Document Server

    Jerkstrand, Anders; Kozma, Cecilia

    2011-01-01

    SN 1987A provides a unique opportunity to study the evolution of a supernova from explosion into very late phases. Due to the rich chemical structure, the multitude of physical process involved, and extensive radiative transfer effects, detailed modeling is needed to interpret the emission from this and other supernovae. In this paper, we analyze the late-time (~8 years) HST spectrum of the SN 1987A ejecta, where 44Ti is the dominant power source. Based on an explosion model for a 19 Msun progenitor, we compute a model spectrum by calculating the degradation of positrons and gamma-rays from the radioactive decays, solving the equations governing temperature, ionization balance and NLTE level populations, and treating the radiative transfer with a Monte Carlo technique. We obtain a UV/optical/NIR model spectrum which is found to reproduce most of the lines in the observed spectrum to good accuracy. We find non-local radiative transfer in atomic lines to be an important process also at this late stage of the su...

  2. Detection of 183 GHz water megamaser emission towards NGC 4945

    CERN Document Server

    Humphreys, Elizabeth; Impellizzeri, Violette; Galametz, Maud; Olberg, Michael; Conway, John; Belitsky, Victor; De Breuck, Carlos

    2016-01-01

    Aim: The aim of this work is to search Seyfert 2 galaxy NGC 4945, a well-known 22 GHz water megamaser galaxy, for water (mega)maser emission at 183 GHz. Method: We used APEX SEPIA Band 5 to perform the observations. Results: We detected 183 GHz water maser emission towards NGC 4945 with a peak flux density of ~3 Jy near the galactic systemic velocity. The emission spans a velocity range of several hundred km/s. We estimate an isotropic luminosity of > 1000 Lsun, classifying the emission as a megamaser. A comparison of the 183 GHz spectrum with that observed at 22 GHz suggests that 183 GHz emission also arises from the active galactic nucleus (AGN) central engine. If the 183 GHz emission originates from the circumnuclear disk, then we estimate that a redshifted feature at 1084 km/s in the spectrum should arise from a distance of 0.022 pc from the supermassive black hole (1.6 x 10(5) Schwarzschild radii), i.e. closer than the water maser emission previously detected at 22 GHz. This is only the second time 183 G...

  3. The large-scale anomalous microwave emission revisited by WMAP

    CERN Document Server

    Lagache, G

    2003-01-01

    We present a new study of the high latitude galactic contributions to the millimeter sky, based on an analysis of the WMAP data combined with several templates of dust emission (DIRBE/COBE and FIRAS/COBE) and gas tracers (HI and Halpha). To study the IR to millimeter properties of the diffuse sky at high galactic latitude, we concentrate on the emission correlated with the HI gas. We compute the emission spectrum of the dust/free-free/synchrotron components associated with HI gas from low to large column densities. A significant residual WMAP emission over the free-free, synchrotron and the dust contribution is found from 3.2 to 9.1 mm. We show that this residual WMAP emission (normalised to 10$^{20}$ atoms/cm$^2$) (1) exhibits a constant spectrum from 3.2 to 9.1 mm and (2) significantly decreases in amplitude when N$_{HI}$ increases, contrary to the HI-normalised far-infrared emission which stays rather constant. It is thus very likely that the residual WMAP emission is not associated with the Large Grain du...

  4. Hard burst emission from the soft gamma repeater SGR 1900+14

    NARCIS (Netherlands)

    P.M. Woods; C. Kouveliotou; J. van Paradijs; M.S. Briggs; K. Hurley; E. Göğüş; R.D. Preece; T.W. Giblin; C. Thompson; R.C. Duncan

    1999-01-01

    We present evidence for burst emission from SGR 1900+14 with a power-law high-energy spectrum extending beyond 500 keV. Unlike previous detections of high-energy photons during bursts from soft gamma repeaters (SGRs), these emissions are not associated with extraordinarily bright flares. Not only is

  5. Is optical Fe II emission related to the soft X-ray properties of quasars?

    Science.gov (United States)

    Wilkes, Belinda J.; Elvis, Martin; Mchardy, Ian

    1987-01-01

    Radio-quiet quasars generally show broad, blended multiplets of Fe II emission in their optical and UV spectra. Radio-loud quasars also show UV Fe II emission, but their optical Fe II emission is generally weaker. No satisfactory theory connecting the generation of Fe II and radio emission has been found to explain this effect. A second, well-established distinction between the two clases of quasar is in their X-ray properties: radio-loud quasars are more X-ray luminous, and recent results have shown that they also have systematically flatter soft X-ray slopes. Here it is proposed that the second effect causes the first; i.e., that the primary factor controlling the optical Fe II emission is the soft X-ray spectrum. This proposition is supported by X-ray and optical data for nine quasars, which shows a correlation between the soft X-ray slope and the strength of the optical Fe II emission. One of these quasars (1803+676) is radio-quiet, and yet its optical spectrum shows no evidence for Fe II emission. This quasar is also unusual in that it has a flat X-ray spectrum. This further supports the proposal that the X-ray spectrum is important in determining the relative strengths of UV and optical Fe II emission.

  6. Hearing the music in the spectrum of hydrogen

    Science.gov (United States)

    LoPresto, Michael C.

    2016-03-01

    Throughout a general education course on sound and light aimed at music and art students, analogies between subjective perceptions of objective properties of sound and light waves are a recurring theme. Demonstrating that the pitch and loudness of musical sounds are related to the frequency and intensity of a sound wave is simple and students are easily able to draw the analogies with the color and brightness of light. When considering an entire spectrum, the presence of multiple frequencies and wavelengths of different intensities is perceived by the ear as sound quality, or musical timbre, while the perception of the eye is the tone or hue of a color. What follows is a description of a demonstration that draws the analogy between musical sound quality and the tone or hue of light in which the emission spectrum of hydrogen is considered and actually played as a musical chord.

  7. [Detonation temperature measurement of epoxypropane using instantaneous spectrum method].

    Science.gov (United States)

    Li, Ying; Li, Ping; Xiao, Hai-Bo; Hu, Dong; Yuan, Chang-Ying

    2008-03-01

    After solving the problems of synchronization of the measuring system and the avoidance of false trigger signal, the instantaneous emission spectrum of epoxypropane with an exposure time of 2 micros and a resolution of 0.2 nm was acquired from a side window of a shock tube at the very moment when the epoxypropane transformed from deflagration to detonation. The measuring system consists of an advanced intensified charge-coupled-device spectroscopic detector, a digital delay generator DG535, an explosion shock tube and optical fibers. The DDT process was monitored by pressure transducers. After correcting the intensity of the spectrum obtained, the background curve of the heat radiation intensity of the detonation was given immediately. The detonation temperature of 2 416 K for epoxypropane was derived from fitting the curve with Planck blackbody formula by least squares principle. The detonation temperature of epoxypropane can provide an experimental datum for analyzing the microscopic mechanism of DDT process.

  8. Shipping emissions in ports

    OpenAIRE

    2014-01-01

    Shipping emissions in ports are substantial, accounting for 18 million tonnes of CO2 emissions, 0.4 million tonnes of NOx, 0.2 million of SOx and 0.03 million tonnes of PM10 in 2011. Around 85% of emissions come from containerships and tankers. Containerships have short port stays, but high emissions during these stays. Most of CO2 emissions in ports from shipping are in Asia and Europe (58%), but this share is low compared to their share of port calls (70%). European ports have much less emi...

  9. International emissions trading

    DEFF Research Database (Denmark)

    Boom, Jan Tjeerd

    This thesis discusses the design and political acceptability of international emissions trading. It is shown that there are several designs options for emissions trading at the national level that have a different impact on output and thereby related factors such as employment and consumer prices....... The differences in impact of the design make that governments may prefer different designs of emissions trading in different situations. The thesis furthermore establishes that international emissions trading may lead to higher overall emissions, which may make it a less attractive instrument....

  10. An Anomalous Component of Galactic Emission

    CERN Document Server

    Leitch, E M; Pearson, T J; Myers, S

    1997-01-01

    We present results from microwave background observations at the Owens Valley Radio Observatory. These observations, at 14.5 and 32 GHz, are designed to detect intrinsic anisotropy on scales of 7'. After point source removal, we detect significant emission with temperature spectral index beta ~ -2 towards the North Celestial Pole (NCP). Comparison of our data with the IRAS 100 micron map of the same fields reveals a strong correlation between this emission and the infrared dust emission. From the lack of detectable H-alpha emission, we conclude that the signals are consistent either with flat-spectrum synchrotron radiation, or with free-free emission from T_e ~ 10^6 K gas, probably associated with a large HI feature known as the NCP Loop. Assuming beta = -2.2, our data indicate a conversion T_f/I_(100 micron) = 0.075*nu(GHz)^-2.2 K/(MJy/sr). The detection of such a component suggests that we should be cautious in any assumptions made regarding foregrounds when designing experiments to map the microwave backgr...

  11. Modified blackbody radiation spectrum of a selective emitter with application to incandescent light source design.

    Science.gov (United States)

    Matsumoto, Takahiro; Tomita, Makoto

    2010-06-21

    Using a selective emitter with high emissivity in the visible wavelength region and low emissivity in the infrared wavelength region, we reduced the infrared contribution to the blackbody radiation spectrum and shifted the peak emission to shorter wavelengths. We made precise measurements of thermal radiation loss. The conversion efficiency from input electric power to visible light radiation was quantitatively evaluated with high accuracy. Using the proposed selective emitter, the conversion efficiencies in excess of 95% could be produced. Our conclusions pave the way for the design of incandescent lamps with luminous efficiencies exceeding 400 lm/W.

  12. [Autism spectrum disorders in adults

    NARCIS (Netherlands)

    Kan, C.C.; Buitelaar, J.K.; Gaag, R.J. van der

    2008-01-01

    Early infantile autism' as defined by Kanner has grown into a spectrum of autistic disorders. The recognition of Asperger's disorder and of pervasive developmental disorder not otherwise specified (PDD-NOS), has led to increased demand for appropriate diagnostic assessment of autism in adults. The e

  13. Primordial power spectrum from Planck

    CERN Document Server

    Hazra, Dhiraj Kumar; Souradeep, Tarun

    2014-01-01

    Using modified Richardson-Lucy algorithm we reconstruct the primordial power spectrum (PPS) from Planck Cosmic Microwave Background (CMB) temperature anisotropy data. In our analysis we use different combinations of angular power spectra from Planck to reconstruct the shape of the primordial power spectrum and locate possible features. Performing an extensive error analysis we found the dip near $\\ell\\sim750-850$ represents the most prominent feature in the data. Feature near $\\ell\\sim1800-2000$ is detectable with high confidence only in 217 GHz spectrum and is apparently consequence of a small systematic as described in the revised Planck 2013 papers. Fixing the background cosmological parameters and the foreground nuisance parameters to their best fit baseline values, we report that the best fit power law primordial power spectrum is consistent with the reconstructed form of the PPS at 2$\\sigma$ C.L. of the estimated errors (apart from the local features mentioned above). As a consistency test, we found the...

  14. Diophantine approximation and automorphic spectrum

    CERN Document Server

    Ghosh, Anish; Nevo, Amos

    2010-01-01

    The present paper establishes qunatitative estimates on the rate of diophantine approximation in homogeneous varieties of semisimple algebraic groups. The estimates established generalize and improve previous ones, and are sharp in a number of cases. We show that the rate of diophantine approximation is controlled by the spectrum of the automorphic representation, and is thus subject to the generalised Ramanujan conjectures.

  15. The low lying glueball spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Adam Szczepaniak; Eric Swanson

    2003-12-18

    The complete low-lying positive charge conjugation glueball spectrum is obtained from QCD. The formalism relies on the construction of an efficient quasiparticle gluon basis for Hamiltonian QCD in Coulomb gauge. The resulting rapidly convergent Fock space expansion is exploited to derive quenched low-lying glueball masses with no free parameters which are in remarkable agreement with lattice gauge theory.

  16. Autism Spectrum Disorders and Epigenetics

    Science.gov (United States)

    Grafodatskaya, Daria; Chung, Brian; Szatmari, Peter; Weksberg, Rosanna

    2010-01-01

    Objective: Current research suggests that the causes of autism spectrum disorders (ASD) are multifactorial and include both genetic and environmental factors. Several lines of evidence suggest that epigenetics also plays an important role in ASD etiology and that it might, in fact, integrate genetic and environmental influences to dysregulate…

  17. Catatonia and Autistic Spectrum Disorders

    Science.gov (United States)

    Hare, Dougal Julian; Malone, Caroline

    2004-01-01

    The phenomenon of catatonic-like states in people with autistic spectrum disorders is discussed in the context of current knowledge about catatonia as it occurs in severe mental illness and, less frequently documented, in conjunction with developmental disorders. The existing literature on catatonic-like states in people with autistic spectrum…

  18. Autism Spectrum Disorders and Epigenetics

    Science.gov (United States)

    Grafodatskaya, Daria; Chung, Brian; Szatmari, Peter; Weksberg, Rosanna

    2010-01-01

    Objective: Current research suggests that the causes of autism spectrum disorders (ASD) are multifactorial and include both genetic and environmental factors. Several lines of evidence suggest that epigenetics also plays an important role in ASD etiology and that it might, in fact, integrate genetic and environmental influences to dysregulate…

  19. Neurofeedback in Autism Spectrum Disorders

    Science.gov (United States)

    Holtmann, Martin; Steiner, Sabina; Hohmann, Sarah; Poustka, Luise; Banaschewski, Tobias; Bolte, Sven

    2011-01-01

    Aim: To review current studies on the effectiveness of neurofeedback as a method of treatment of the core symptoms of autism spectrum disorders (ASD). Method: Studies were selected based on searches in PubMed, Ovid MEDLINE, EMBASE, ERIC, and CINAHL using combinations of the following keywords: "Neurofeedback" OR "EEG Biofeedback" OR "Neurotherapy"…

  20. Army PM UAS Spectrum Update

    Science.gov (United States)

    2012-07-01

    35.15GHz Sierra Nevada Corporation ( SNC ) 1 Aircraft (Wing) J/F-12 06982 TALS TS - Ground Unit RX 34.85 to 35.15GHz TX 34.78 to 35.08GHz Sierra...Nevada Corporation ( SNC ) 2 Runway J/F-12 06982 UNCLASSIFIED UNCLASSIFIED Gray Eagle RF Spectrum Requirements 23 System Component

  1. [Autism spectrum disorders in adults

    NARCIS (Netherlands)

    Kan, C.C.; Buitelaar, J.K.; Gaag, R.J. van der

    2008-01-01

    Early infantile autism' as defined by Kanner has grown into a spectrum of autistic disorders. The recognition of Asperger's disorder and of pervasive developmental disorder not otherwise specified (PDD-NOS), has led to increased demand for appropriate diagnostic assessment of autism in adults. The

  2. Nonthermal Emission of Tycho's Supernova Remnant

    Institute of Scientific and Technical Information of China (English)

    TANG Yun-Yong; FANG Jun; ZHANG Li

    2011-01-01

    The time-dependent non-thermal particle and photon spectra are reproduced for a Type Ia SNR Tycho with radio,x-ray,GeV and TeV emission within the framework of the diffusive shock acceleration of the non-thermal particles.TeV photons can come from the inverse Compton scattering of relativistic electrons and from the π0-decay process in proton-proton interaction.The results show that (1) the hadronic case can model the observed multiwavelength spectrum well and,peculiarly,the π0-decay process appears to be necessary to explain the GeV emission;and (2) magnetic field amplification is vital in the SNR.Tycho's supernova remnant (SNR) is a Type Ia SNR with an age of 438 y.At radio band,the images indicate a clear shell-like morphology with enhanced emission along the northeastern edge of the remnant,[1,2] the spectral index and the fiux density at 1.4 GHz are 0.65 and 40.5 Jy,respectively.[3]%The time-dependent non-thermal particle and photon spectra are reproduced for a Type /a SNR Tycho with radio, x-ray, GeV and TeV emission within the framework of the diffusive shock acceleration of the non-thermal particles. TeV photons can come from the inverse Compton scattering of relativistic electrons and from theπ°-decay process in proton-proton interaction. The results show that (1) the hadronic case can model the observed multiwavelength spectrum well and, peculiarly, the π°-decay process appears to be necessary to explain the GeV emission; and (2) magnetic field amplification is vital in the SNR.

  3. Spinning Dust Emission: Effects of irregular grain shape, transient heating and comparison with WMAP results

    CERN Document Server

    Hoang, Thiem; Draine, B T

    2011-01-01

    Planck is expected to answer crucial questions on the early Universe, but it also provides further understanding on anomalous microwave emission. Electric dipole emission from spinning dust grains continues to be the favored interpretation of anomalous microwave emission. In this paper, we present a method to calculate the rotational emission from small grains of irregular shape with moments of inertia $I_{1}\\ge I_{2}\\ge I_{3}$. We show that a torque-free rotating irregular grain with a given angular momentum radiates at multiple frequency modes. The resulting spinning dust spectrum has peak frequency and emissivity increasing with the degree of grain shape irregularity, which is defined by $I_{1}:I_{2}:I_{3}$. We discuss how the orientation of dipole moment $\\bmu$ in body coordinates affects the spinning dust spectrum for different regimes of internal thermal fluctuations. We show that the spinning dust emissivity for the case of strong thermal fluctuations is less sensitive to the orientation of $\\bmu$ than...

  4. Delay Spectrum with Phase-Tracking Arrays: Extracting the HI power spectrum from the Epoch of Reionization

    CERN Document Server

    Paul, Sourabh; Morales, Miguel F; Dwarkanath, K S; Shankar, N Udaya; Subrahmanyan, Ravi; Barry, N; Beardsley, A P; Bowman, Judd D; Briggs, F; Carroll, P; de Oliveira-Costa, A; Dillon, Joshua S; Ewall-Wice, A; Feng, L; Greenhill, L J; Gaensler, B M; Hazelton, B J; Hewitt, J N; Hurley-Walker, N; Jacobs, D J; Kim, Han-Seek; Kittiwisit, P; Lenc, E; Line, J; Loeb, A; McKinley, B; Mitchell, D A; Neben, A R; Offringa, A R; Pindor, B; Pober, J C; Procopio, P; Riding, J; Sullivan, I S; Tegmark, M; Thyagarajan, Nithyanandan; Tingay, S J; Trott, C M; Wayth, R B; Webster, R L; Wyithe, J S B; Cappallo, Roger; Johnston-Hollitt, M; Kaplan, D L; Lonsdale, C J; McWhirter, S R; Morgan, E; Oberoi, D; Ord, S M; Prabu, T; Srivani, K S; Williams, A; Williams, C L

    2016-01-01

    The Detection of redshifted 21 cm emission from the epoch of reionization (EoR) is a challenging task owing to strong foregrounds that dominate the signal. In this paper, we propose a general method, based on the delay spectrum approach, to extract HI power spectra that is applicable to tracking observations using an imaging radio interferometer (Delay Spectrum with Imaging Arrays (DSIA)). Our method is based on modelling the HI signal taking into account the impact of wide field effects such as the $w$-term which are then used as appropriate weights in cross-correlating the measured visibilities. Our method is applicable to any radio interferometer that tracks a phase center and could be utilized for arrays such as MWA, LOFAR, GMRT, PAPER and HERA. In the literature the delay spectrum approach has been implemented for near-redundant baselines using drift scan observations. In this paper we explore the scheme for non-redundant tracking arrays, and this is the first application of delay spectrum methodology to...

  5. EVN observations of low-luminosity flat-spectrum active galactic nuclei

    NARCIS (Netherlands)

    Caccianiga, A; Marcha, MJM; Thean, A; Dennett-Thorpe, J

    2001-01-01

    We present and discuss the results of very-long baseline interferometry (VLBI, EVN) observations of three low-luminosity (P-5GHz <10(25) W Hz(-1)) broad emission line active galactic nuclei (AGNs) carefully selected from a sample of flat-spectrum radio sources (CLASS). Based on the total and the ext

  6. The EUV Spectrum of Sunspot Plumes Observed by SUMER on SOHO

    Indian Academy of Sciences (India)

    W. Curdt; B. N. Dwivedi; U. Feldman

    2000-09-01

    We present results from sunspot observations obtained by SUMER on SOHO. In sunspot plumes the EUV spectrum differs from the quiet Sun; continua are observed with different slopes and intensities; emission lines from molecular hydrogen and many unidentified species indicate unique plasma conditions above sunspots. Sunspot plumes are sites of systematic downflow. We also discuss the properties of sunspot oscillations.

  7. Observing broad-absorption line quasars with Spectrum-Rontgen-Gamma

    DEFF Research Database (Denmark)

    Singh, K.P.; Schnopper, H.W.; Westergaard, Niels Jørgen Stenfeldt

    1998-01-01

    Broad-absorption line quasars are found to have extremely weak soft X-ray emission when compared with other optically selected quasars. In the only example of PHL 5200 for which a detailed X-ray spectrum has been obtained with ASCA, strong absorption in the source appears to be responsible...

  8. EVN observations of low-luminosity flat-spectrum active galactic nuclei

    NARCIS (Netherlands)

    Caccianiga, A; Marcha, MJM; Thean, A; Dennett-Thorpe, J

    2001-01-01

    We present and discuss the results of very-long baseline interferometry (VLBI, EVN) observations of three low-luminosity (P-5GHz <10(25) W Hz(-1)) broad emission line active galactic nuclei (AGNs) carefully selected from a sample of flat-spectrum radio sources (CLASS). Based on the total and the

  9. Cortical Serotonin Type-2 Receptor Density in Parents of Children with Autism Spectrum Disorders

    Science.gov (United States)

    Goldberg, Jeremy; Anderson, George M.; Zwaigenbaum, Lonnie; Hall, Geoffrey B. C.; Nahmias, Claude; Thompson, Ann; Szatmari, Peter

    2009-01-01

    Parents (N = 19) of children with autism spectrum disorders (ASD) and adult controls (N = 17) underwent positron emission tomography (PET) using [[superscript 18]F]setoperone to image cortical serotonin type-2 (5-HT2) receptors. The 5-HT2 binding potentials (BPs) were calculated by ratioing [[superscript 18]F]setoperone intensity in regions of…

  10. Characterizing the emissivity of materials under dynamic compression (final report for LDRD project 79877).

    Energy Technology Data Exchange (ETDEWEB)

    Dolan, Daniel H.

    2007-10-01

    Temperature measurements are crucial to equation of state development, but difficult to perform reliably. In the case of infrared pyrometry, a large uncertainty comes from the fact that sample emissivity (the deviation from a blackbody) is unknown. In this project, a method for characterizing the emissivity of shocked materials was developed. By coupling infrared radiation from the National Synchrotron Light Source to a gas gun system, broad spectrum emissivity changes were studied to a peak stress of 8 GPa. Emissivity measurements were performed on standard metals (Al, Cr, Cu, and Pt) as well as a high emissivity coating developed at Sandia.

  11. Generalized eigenvalue based spectrum sensing

    KAUST Repository

    Shakir, Muhammad

    2012-01-01

    Spectrum sensing is one of the fundamental components in cognitive radio networks. In this chapter, a generalized spectrum sensing framework which is referred to as Generalized Mean Detector (GMD) has been introduced. In this context, we generalize the detectors based on the eigenvalues of the received signal covariance matrix and transform the eigenvalue based spectrum sensing detectors namely: (i) the Eigenvalue Ratio Detector (ERD) and two newly proposed detectors which are referred to as (ii) the GEometric Mean Detector (GEMD) and (iii) the ARithmetic Mean Detector (ARMD) into an unified framework of generalize spectrum sensing. The foundation of the proposed framework is based on the calculation of exact analytical moments of the random variables of the decision threshold of the respective detectors. The decision threshold has been calculated in a closed form which is based on the approximation of Cumulative Distribution Functions (CDFs) of the respective test statistics. In this context, we exchange the analytical moments of the two random variables of the respective test statistics with the moments of the Gaussian (or Gamma) distribution function. The performance of the eigenvalue based detectors is compared with the several traditional detectors including the energy detector (ED) to validate the importance of the eigenvalue based detectors and the performance of the GEMD and the ARMD particularly in realistic wireless cognitive radio network. Analytical and simulation results show that the newly proposed detectors yields considerable performance advantage in realistic spectrum sensing scenarios. Moreover, the presented results based on proposed approximation approaches are in perfect agreement with the empirical results. © 2012 Springer Science+Business Media Dordrecht.

  12. Spectrum Simulation of Li-Like Aluminium Plasma

    Institute of Scientific and Technical Information of China (English)

    PENG Feng; JIANG Gang; ZHU Zheng-He

    2006-01-01

    X-ray emission spectra for L-shell of Li-like aluminium ions are simulated by using the flexible atomic code based on the collisional radiative model. Atomic processes including radiative recombination, dielectronic recombination, collisional ionization and resonance excitation from the neighbouring ion (Al9+ and Al11+) charge states of the target ion (Al10+) are considered in the model. In addition, the contributions of different atomic processes to the x-ray spectrum are analysed. The results show that dielectronic recombination, radiative recombination, collisional ionization and resonance excitation, other than direct collisional excitation, are very important processes.

  13. Simulations of the spectrum from a photoionized Si plasma

    Science.gov (United States)

    Lihua, Bao; Zeqing, Wu; Bin, Duan; Yongkun, Ding; Jun, Yan

    2011-02-01

    In order to interpret the spectrum of a photoionized Si plasma, we calculate the level populations and emissions using a collisional-radiative equilibrium model with detailed atomic data. In our calculations, levels with principal quantum number up to 9 are included and the electron impact processes are also taken into account. The peak around 1855 eV, which is not reproduced in the previous simulation, is obvious in the present results. Spectra analyzing shows that this peak mainly comes from the intercombination line of He-like Si. Our calculations indicate that the electron impact processes enhance this intercombination line about once, although the electron temperature is pretty low.

  14. Spectrum analysis of hydrogen plasma in spherically convergent beam fusion

    Energy Technology Data Exchange (ETDEWEB)

    Ogasawara, Kazuki; Yamauchi, Kunihito; Watanabe, Masato; Sunaga, Yoshitaka; Hotta, Eiki [Tokyo Institute of Technology, Dept. of Energy Sciences, Yokohama, Kanagawa (Japan); Okino, Akitoshi [Tokyo Institute of Technology, Dept. of Electrical and Electronic Engineering, Tokyo (Japan)

    2001-09-01

    Spectroscopic analysis of spherical glow discharge fusion device was carried out using hydrogen gas. Effects of the discharge current and cathode voltage on spectrum profiles of hydrogen Balmar lines were measured. The profiles of all hydrogen lines were broadened with the cathode voltage. From the relationship between the maximum broadening width and the cathode voltage, it was indicated that the broadening was caused by the Doppler effect. From the spatial distribution of emission intensity, it was found that plasma core size became larger with discharge current and smaller with cathode voltage. (author)

  15. Confronting GRB prompt emission with a model for subphotospheric dissipation

    CERN Document Server

    Ahlgren, Björn; Nymark, Tanja; Ryde, Felix; Pe'er, Asaf

    2015-01-01

    The origin of the prompt emission in gamma-ray bursts (GRBs) is still an unsolved problem and several different mechanisms have been suggested. Here we fit Fermi GRB data with a photospheric emission model which includes dissipation of the jet kinetic energy below the photosphere. The resulting spectra are dominated by Comptonization and contain no significant contribution from synchrotron radiation. In order to fit to the data we span a physically motivated part of the model's parameter space and create DREAM ($\\textit{Dissipation with Radiative Emission as A table Model}$), a table model for ${\\scriptsize XSPEC}$. We show that this model can describe different kinds of GRB spectra, including GRB 090618, representing a typical Band function spectrum, and GRB 100724B, illustrating a double peaked spectrum, previously fitted with a Band+blackbody model, suggesting they originate from a similar scenario. We suggest that the main difference between these two types of bursts is the optical depth at the dissipatio...

  16. Multilayer Photonic Crystal for Spectral Narrowing of Emission

    Directory of Open Access Journals (Sweden)

    Zhanfang LIU

    2017-08-01

    Full Text Available Multilayer colloidal crystal has been prepared by the layer-by-layer deposition of silica microspheres on a glass slide. Each layer is a slab consisting of a fcc close-packed colloidal arrays. By properly choosing the sizes of spheres, the whole spectral feature of multilayer colloidal crystal can be tuned. Here, we engineered a multilayer superlattice structure with an effective passband between two stop bands. This gives a strong narrowing effect on emission spectrum. With the stop bands at the shortwave and longwave edges of emission spectrum, the passband in the central wavelength region can be regarded as a strong decrease of suppression effect and enhancement of a narrow wavelength region of emission. The spectral narrowing modification effect of suitably engineered colloidal crystals shows up their importance in potential application as optical filters and lasing devices.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16320

  17. Spectrum Trading in India and 5G

    DEFF Research Database (Denmark)

    Tripathi, Purnendu; Prasad, Ramjee

    2013-01-01

    Currently radio spectrum is largely managed through Command and Control method. Public mobile services require spectrum below 3 GHz for providing cost effective services. The existing method has created artificial shortage of spectrum especially below 3 GHz. Spectrum trading is a new concept...... in which service providers are permitted to purchase spectrum from the market to fulfil their requirements. Spectrum trading has not yet been permitted in India. This paper provides an overview of possibilities of spectrum trading in India and concludes that necessary ingredients are present in India...... for spectrum trading and it could provide a boost to the Indian telecom sector. Further, it will also discuss spectrum issue related with 5G in the direction of millimeter waves....

  18. Broadband enhancement of spontaneous emission in a photonic-plasmonic structure

    DEFF Research Database (Denmark)

    Zhu, Xiaolong; Xie, Fengxian; Shi, Lei

    2012-01-01

    We demonstrate that a broadband enhancement of spontaneous emission can be achieved within a photonic-plasmonic structure. The structure can strongly modify the spontaneous emission by exciting plasmonic modes. Because of the excited plasmonic modes, an enhancement up to 30 times is observed, lea......, leading to a 4 times broader emission spectrum. The reflectance measurement and the finite-difference time-domain simulation are carried out to support these results....

  19. The complete submillimetre spectrum of NGC 891

    CERN Document Server

    Dupac, X; Bernard, J P; Giard, M; Lamarre, J M; Laureijs, R J; Pajot, F; Ristorcelli, I; Serra, G; Tauber, J; Torre, J P

    2003-01-01

    Submillimetre maps of NGC 891 have been obtained with the PRONAOS balloon-borne telescope and with the ISOPHOT instrument on board the ISO satellite. In this article, we also gather data from IRAS and SCUBA to present the complete submillimetre spectrum of this nearby edge-on spiral galaxy. We derive submillimetre emission profiles along the major axis. The modified blackbody fits, assuming a single dust component, lead to temperatures of 19-24 K toward the centre and 18-20 K toward the edges, with possible variations of the dust spectral index from 1.4 to 2. The two-component fits lead to a warm component temperature of 29 K all along the galaxy with a cold component at 16 K. The interstellar medium masses derived by these two methods are quite different: 4.6 x 10^9 Mo in the case of the one-component model and 12 x 10^9 Mo in the case of the two-component one. This two-component fit indicates that the cold dust to warm dust ratio is 20 to 40, the highest values being in the wings of this galaxy. Comparing t...

  20. The Nuclear Spectrum of M87

    CERN Document Server

    Tsvetanov, Z I; Ford, H C; Kriss, G A; Dopita, M A; Dressel, L L; Harms, R J

    1998-01-01

    The nuclear spectrum of M87 covering the Ly_a-H_a wavelength range was obtained with the HST Faint Object Spectrograph (FOS) trough a 0.21 arcsec aperture. Contrary to some previous claims, a single power law (F(nu)~nu^(-a)) can not reproduce the observed continuum shape and at least a broken power law is require for a good fit (a = 1.75 and 1.41 shortward and longward of the break at ~4500 A). We detect a set of broad (FWHM ~ 400 km/s) absorption lines arising in the gas associated with M87. These are only lines from neutral and very low ionization species blueshifted by ~150 km/s relative to the M87 systemic velocity, indicating a net gas outflow and turbulence. The excitation sensitive emission line ratios suggest that shocks may be the dominant energy supplier. The nuclear source in M87 is significantly variable. From the FOS target acquisition data, we have established that the flux from the optical nucleus varies by a factor ~2 on time scales of ~2.5 months and by as much as 25% over 3 weeks, and remain...