Science.gov

Sample records for controlling spontaneous emission

  1. Controlling spontaneous emission in bioreplica photonic crystals

    NASA Astrophysics Data System (ADS)

    Jorgensen, Matthew R.; Butler, Elizabeth S.; Bartl, Michael H.

    2012-04-01

    Sophisticated methods have been created by nature to produce structure-based colors as a way to address the need of a wide variety of organisms. This pallet of available structures presents a unique opportunity for the investigation of new photonic crystal designs. Low-temperature sol-gel biotemplating methods were used to transform a single biotemplate into a variety of inorganic oxide structures. The density of optical states was calculated for a diamond-based natural photonic crystal, as well as several structures templated from it. Calculations were experimentally probed by spontaneous emission studies using time correlated single photon counting measurements.

  2. Ultrafast non-local control of spontaneous emission.

    PubMed

    Jin, Chao-Yuan; Johne, Robert; Swinkels, Milo Y; Hoang, Thang B; Midolo, Leonardo; van Veldhoven, Peter J; Fiore, Andrea

    2014-11-01

    The radiative interaction of solid-state emitters with cavity fields is the basis of semiconductor microcavity lasers and cavity quantum electrodynamics (CQED) systems. Its control in real time would open new avenues for the generation of non-classical light states, the control of entanglement and the modulation of lasers. However, unlike atomic CQED or circuit quantum electrodynamics, the real-time control of radiative processes has not yet been achieved in semiconductors because of the ultrafast timescales involved. Here we propose an ultrafast non-local moulding of the vacuum field in a coupled-cavity system as an approach to the control of radiative processes and demonstrate the dynamic control of the spontaneous emission (SE) of quantum dots (QDs) in a photonic crystal (PhC) cavity on a ? 200 ps timescale, much faster than their natural SE lifetimes. PMID:25218324

  3. Ultrafast non-local control of spontaneous emission

    NASA Astrophysics Data System (ADS)

    Jin, Chao-Yuan; Johne, Robert; Swinkels, Milo Y.; Hoang, Thang B.; Midolo, Leonardo; van Veldhoven, Peter J.; Fiore, Andrea

    2014-11-01

    The radiative interaction of solid-state emitters with cavity fields is the basis of semiconductor microcavity lasers and cavity quantum electrodynamics (CQED) systems. Its control in real time would open new avenues for the generation of non-classical light states, the control of entanglement and the modulation of lasers. However, unlike atomic CQED or circuit quantum electrodynamics, the real-time control of radiative processes has not yet been achieved in semiconductors because of the ultrafast timescales involved. Here we propose an ultrafast non-local moulding of the vacuum field in a coupled-cavity system as an approach to the control of radiative processes and demonstrate the dynamic control of the spontaneous emission (SE) of quantum dots (QDs) in a photonic crystal (PhC) cavity on a ?200 ps timescale, much faster than their natural SE lifetimes.

  4. Controlled spontaneous emission in erbium-doped microphotonic materials

    NASA Astrophysics Data System (ADS)

    Kalkman, Jeroen

    2005-03-01

    Erbium is a rare-earth metal that, when incorporated in a solid, can emit light at a wavelength of 1.5 ?m. It plays a key role in current day telecommunication technology as the principle ingredient of optical fiber amplifiers. In this thesis the control of the Er spontaneous emission in three different types of microphotonic materials is described. Part I of this thesis focuses on the effect of a metallo-dielectric interface on the spontaneous emission of optical emitters in silica glass. It is shown that Er ions near a Ag interface can couple to surface plasmons (SPs) via a near-field interaction. By coupling SPs out into the far field, large changes in the Er photoluminescence emission distribution, spectra, and polarization can be observed. The excitation of SPs also results in an increase of the Er photoluminescence decay rate. The observed decay rates are in good agreement with calculations based on a classical dipole oscillator model. From the change in photoluminescence decay rate of Si nanocrystals near a Ag interface it is shown that Si nanocrystals can efficiently excite SPs and have an internal quantum efficiency of 77 %. Part II focuses on the effect of a microcavity on the spontaneous emission of Er and describes how ion implantation can be used to dope dielectric microresonators with optically active Er ions. The fabrication and characterization of an Er ion-implanted silica microsphere resonator is described that shows lasing at 1.5 ?m when pumped above its lasing threshold. Ion implantation is also used to dope toroidal microcavities on a Si chip with Er. The microtoroids are doped by either pre-implantation into the SiO2 base material, or by post-implantation in a fully fabricated microtoroid. The optical activation of Er ions in the microtoroid is investigated and Er lasing at 1.5 ?m is observed for both types of microcavities with the lowest threshold (4.5 ?W) for the pre-implanted microtoroids. Part III describes the fabrication of an Er-doped Si-inverse opal photonic crystal. These photonic crystals can potentially have a photonic bandgap that can fully inhibit the spontaneous emission of on optical emitter. Fabrication criteria are derived for such a photonic crystal, based on the lattice parameter, filling fraction, and Si refractive index. In the opal photonic crystal composed of both Si and SiO2 we show that Er ions can be selectively excited in both the Si and SiO2 part of the photonic crystal by changing the excitation wavelength and/or the measurement temperature.

  5. Active magneto-optical control of spontaneous emission in graphene

    SciTech Connect

    Kort-Kamp, W. J. M.; Amorim, B.; Bastos, G.; Pinheiro, F. A.; Rosa, F. S. S.; Peres, N. M. R.; Farina, C.

    2015-11-13

    In this study, we investigate the spontaneous emission rate of a two-level quantum emitter near a graphene-coated substrate under the influence of an external magnetic field or strain induced pseudomagnetic field. We demonstrate that the application of the magnetic field can substantially increase or decrease the decay rate. We show that a suppression as large as 99% in the Purcell factor is achieved even for moderate magnetic fields. The emitter's lifetime is a discontinuous function of |B|, which is a direct consequence of the occurrence of discrete Landau levels in graphene. We demonstrate that, in the near-field regime, the magnetic field enables an unprecedented control of the decay pathways into which the photon/polariton can be emitted. Our findings strongly suggest that a magnetic field could act as an efficient agent for on-demand, active control of light-matter interactions in graphene at the quantum level.

  6. Active magneto-optical control of spontaneous emission in graphene

    NASA Astrophysics Data System (ADS)

    Kort-Kamp, W. J. M.; Amorim, B.; Bastos, G.; Pinheiro, F. A.; Rosa, F. S. S.; Peres, N. M. R.; Farina, C.

    2015-11-01

    We investigate the spontaneous emission rate of a two-level quantum emitter near a graphene-coated substrate under the influence of an external magnetic field or strain induced pseudomagnetic field. We demonstrate that the application of the magnetic field can substantially increase or decrease the decay rate. We show that a suppression as large as 99 % in the Purcell factor is achieved even for moderate magnetic fields. The emitter's lifetime is a discontinuous function of |B | , which is a direct consequence of the occurrence of discrete Landau levels in graphene. We demonstrate that, in the near-field regime, the magnetic field enables an unprecedented control of the decay pathways into which the photon/polariton can be emitted. Our findings strongly suggest that a magnetic field could act as an efficient agent for on-demand, active control of light-matter interactions in graphene at the quantum level.

  7. Active magneto-optical control of spontaneous emission in graphene

    DOE PAGESBeta

    Kort-Kamp, W. J. M.; Amorim, B.; Bastos, G.; Pinheiro, F. A.; Rosa, F. S. S.; Peres, N. M. R.; Farina, C.

    2015-11-13

    In this study, we investigate the spontaneous emission rate of a two-level quantum emitter near a graphene-coated substrate under the influence of an external magnetic field or strain induced pseudomagnetic field. We demonstrate that the application of the magnetic field can substantially increase or decrease the decay rate. We show that a suppression as large as 99% in the Purcell factor is achieved even for moderate magnetic fields. The emitter's lifetime is a discontinuous function of |B|, which is a direct consequence of the occurrence of discrete Landau levels in graphene. We demonstrate that, in the near-field regime, the magneticmore » field enables an unprecedented control of the decay pathways into which the photon/polariton can be emitted. Our findings strongly suggest that a magnetic field could act as an efficient agent for on-demand, active control of light-matter interactions in graphene at the quantum level.« less

  8. Controlling spontaneous emission dynamics in semiconductor micro cavities

    NASA Astrophysics Data System (ADS)

    Gayral, B.

    Spontaneous emission of light can be controlled, cavity quantum electrodynamics tells us, and many experiments in atomic physics demonstrated this fact. In particular, coupling an emitter to a resonant photon mode of a cavity can enhance its spontaneous emission rate: this is the so-called Purcell effect. Though appealing it might seem to implement these concepts for the benefit of light-emitting semiconductor devices, great care has to be taken as to which emitter/cavity system should be used. Semiconductor quantum boxes prove to be good candidates for witnessing the Purcell effect. Also, low volume cavities having a high optical quality in other words a long photon storage time are required. State-of-the-art fabrication techniques of such cavities are presented and discussed.We demonstrate spontaneous emission rate enhancement for InAs/GaAs quantum boxes in time-resolved and continuous-wave photoluminescence experiments. This is done for two kinds of cavities, namely GaAs/AlAs micropillars (global enhancement by a factor of 5), and GaAs microdisks (global enhancement by a factor of 20). Prospects for lasers, light-emitting diodes and single photon sources based on the Purcell effect are discussed. L'mission spontane de lumire peut tre contrle, ainsi que nous l'enseigne l'lectrodynamique quantique en cavit, ce fait a t dmontr exprimentalement en physique atomique. En particulier, coupler un metteur un mode photonique rsonnant d'une cavit peut exalter son taux d'mission spontane : c'est l'effet Purcell. Bien qu'il semble trs prometteur de mettre en pratique ces concepts pour amliorer les dispositifs semi-conducteurs metteurs de lumire, le choix du systme metteur/cavit est crucial. Nous montrons que les botes quantiques semi-conductrices sont des bons candidats pour observer l'effet Purcell. Il faut par ailleurs des cavits de faible volume ayant une grande qualit optique en d'autres mots un long temps de stockage des photons. Des techniques de fabrication l'tat de l'art de telles cavits sont prsentes et discutes.Nous dmontrons une exaltation du taux d'mission spontane pour des botes quantiques InAs/GaAs dans des expriences de photoluminescence rsolues en temps et en continu. Ceci est ralis pour deux types de cavits, savoir des micropiliers GaAs/AlAs (exaltation globale par un facteur 5) et des microdisques (exaltation globale d'un facteur 20). Quelques perspectives pour l'application de l'effet Purcell des lasers, des diodes lectroluminescentes et des sources de photons uniques sont prsentes et discutes.

  9. Plasmonic phase-gradient metasurface for spontaneous emission control

    NASA Astrophysics Data System (ADS)

    Langguth, L.; Schokker, A. H.; Guo, K.; Koenderink, A. F.

    2015-11-01

    We combine the concept of phase-gradient metasurfaces with fluorescence directionality control of an ensemble of incoherent emitters. We design a periodic metasurface to control the scattering amplitude of the lattice in momentum space. The lattice is embedded in a waveguiding layer doped with organic fluorophores. In contrast to the usual symmetric directionality that plasmonic lattices impart on emission, we find that the phase gradient translates into asymmetric directional emission into the far field, determined by scattering on a subset of the reciprocal lattice vectors. The measured asymmetry is well explained by analytical modeling.

  10. Quantum dot spontaneous emission control in a ridge waveguide

    SciTech Connect

    Stepanov, Petr; Delga, Adrien; Bleuse, Joël; Dupuy, Emmanuel; Peinke, Emanuel; Gérard, Jean-Michel; Claudon, Julien; Zang, Xiaorun; Lalanne, Philippe

    2015-01-26

    We investigate the spontaneous emission (SE) of self-assembled InAs quantum dots (QDs) embedded in GaAs ridge waveguides that lay on a low index substrate. In thin enough waveguides, the coupling to the fundamental guided mode is vanishingly small. A pronounced anisotropy in the coupling to non-guided modes is then directly evidenced by normal-incidence photoluminescence polarization measurements. In this regime, a measurement of the QD decay rate reveals a SE inhibition by a factor up to 4. In larger wires, which ensure an optimal transverse confinement of the fundamental guided mode, the decay rate approaches the bulk value. Building on the good agreement with theoretical predictions, we infer from calculations the fraction β of SE coupled to the fundamental guided mode for some important QD excitonic complexes. For a charged exciton (isotropic in plane optical dipole), β reaches 0.61 at maximum for an on-axis QD. In the case of a purely transverse linear optical dipole, β increases up to 0.91. This optimal configuration is achievable through the selective excitation of one of the bright neutral excitons.

  11. Single Photon Subradiance: Quantum Control of Spontaneous Emission and Ultrafast Readout

    NASA Astrophysics Data System (ADS)

    Scully, Marlan O.

    2015-12-01

    Recent work has shown that collective single photon emission from an ensemble of resonate two-level atoms, i.e., single photon superradiance, is a rich field of study. The present Letter addresses the flip side of superradiance, i.e., subradiance. Single photon subradiant states are potentially stable against collective spontaneous emission and can have ultrafast readout. In particular it is shown how many atom collective effects provide a new way to control spontaneous emission by preparing and switching between subradiant and superradiant states.

  12. Single Photon Subradiance: Quantum Control of Spontaneous Emission and Ultrafast Readout.

    PubMed

    Scully, Marlan O

    2015-12-11

    Recent work has shown that collective single photon emission from an ensemble of resonate two-level atoms, i.e., single photon superradiance, is a rich field of study. The present Letter addresses the flip side of superradiance, i.e., subradiance. Single photon subradiant states are potentially stable against collective spontaneous emission and can have ultrafast readout. In particular it is shown how many atom collective effects provide a new way to control spontaneous emission by preparing and switching between subradiant and superradiant states. PMID:26705632

  13. Nanoscale imaging and spontaneous emission control with a single nano-positioned quantum dot

    NASA Astrophysics Data System (ADS)

    Ropp, Chad; Cummins, Zachary; Nah, Sanghee; Fourkas, John T.; Shapiro, Benjamin; Waks, Edo

    2013-02-01

    Plasmonic nanostructures confine light on the nanoscale, enabling ultra-compact optical devices that exhibit strong light-matter interactions. Quantum dots are ideal for probing plasmonic devices because of their nanoscopic size and desirable emission properties. However, probing with single quantum dots has remained challenging because their small size also makes them difficult to manipulate. Here we demonstrate the use of quantum dots as on-demand probes for imaging plasmonic nanostructures, as well as for realizing spontaneous emission control at the single emitter level with nanoscale spatial accuracy. A single quantum dot is positioned with microfluidic flow control to probe the local density of optical states of a silver nanowire, achieving 12?nm imaging accuracy. The high spatial accuracy of this scanning technique enables a new method for spontaneous emission control where interference of counter-propagating surface plasmon polaritons results in spatial oscillations of the quantum dot lifetime as it is positioned along the wire axis.

  14. Nanoscale imaging and spontaneous emission control with a single nano-positioned quantum dot.

    PubMed

    Ropp, Chad; Cummins, Zachary; Nah, Sanghee; Fourkas, John T; Shapiro, Benjamin; Waks, Edo

    2013-01-01

    Plasmonic nanostructures confine light on the nanoscale, enabling ultra-compact optical devices that exhibit strong light-matter interactions. Quantum dots are ideal for probing plasmonic devices because of their nanoscopic size and desirable emission properties. However, probing with single quantum dots has remained challenging because their small size also makes them difficult to manipulate. Here we demonstrate the use of quantum dots as on-demand probes for imaging plasmonic nanostructures, as well as for realizing spontaneous emission control at the single emitter level with nanoscale spatial accuracy. A single quantum dot is positioned with microfluidic flow control to probe the local density of optical states of a silver nanowire, achieving 12 nm imaging accuracy. The high spatial accuracy of this scanning technique enables a new method for spontaneous emission control where interference of counter-propagating surface plasmon polaritons results in spatial oscillations of the quantum dot lifetime as it is positioned along the wire axis. PMID:23385591

  15. Controlling spontaneous emission rates of quantum dots with plasmonic nanopatch antennas

    NASA Astrophysics Data System (ADS)

    Hoang, Thang; Akselrod, Gleb; Argyropoulos, Christos; Huang, Jiani; Smith, David; Mikkelsen, Maiken

    2015-03-01

    The radiative processes associated with quantum emitters can be strongly enhanced due to intense electromagnetic fields created by plasmonic nanostructures. Here, we experimentally demonstrate large enhancements of the spontaneous emission rate of colloidal quantum dots coupled to single plasmonic nanopatch antennas. The antennas consist of silver nanocubes (75 nm) coupled to a gold film separated by a thin polyelectrolyte spacer layer (~1 nm) and core-shell CdSe/ZnS quantum dots (~6 nm). By optimizing the size of the nanopatch antenna, the plasmonic mode is tuned to be on resonance with the quantum dot emission. We show an increase in the spontaneous emission rate by a factor of 880 (Purcell factor) and a 2300-fold enhancement in the total fluorescence while maintaining a high radiative quantum efficiency of ~50 %. The nanopatch antenna, as demonstrated here, offers highly directional and broadband radiation that can be tailored for emitters from the visible to the near infrared, providing a promising approach for the spontaneous emission control of single quantum emitters.

  16. Quantum state-controlled directional spontaneous emission of photons into a nanophotonic waveguide

    PubMed Central

    Mitsch, R.; Sayrin, C.; Albrecht, B.; Schneeweiss, P.; Rauschenbeutel, A.

    2014-01-01

    The spin of light in subwavelength-diameter waveguides can be orthogonal to the propagation direction of the photons because of the strong transverse confinement. This transverse spin changes sign when the direction of propagation is reversed. Using this effect, we demonstrate the directional spontaneous emission of photons by laser-trapped caesium atoms into an optical nanofibre and control their propagation direction by the excited state of the atomic emitters. In particular, we tune the spontaneous emission into the counter-propagating guided modes from symmetric to strongly asymmetric, where more than % of the optical power is launched into one or the other direction. We expect our results to have important implications for research in quantum nanophotonics and for implementations of integrated optical signal processing in the quantum regime. PMID:25502565

  17. Controlling the spontaneous emission rate of monolayer MoS2 in a photonic crystal nanocavity

    PubMed Central

    Gan, Xuetao; Gao, Yuanda; Fai Mak, Kin; Yao, Xinwen; Shiue, Ren-Jye; van der Zande, Arend; Trusheim, Matthew E.; Hatami, Fariba; Heinz, Tony F.; Hone, James; Englund, Dirk

    2013-01-01

    We report on controlling the spontaneous emission (SE) rate of a molybdenum disulfide (MoS2) monolayer coupled with a planar photonic crystal (PPC) nanocavity. Spatially resolved photoluminescence (PL) mapping shows strong variations of emission when the MoS2 monolayer is on the PPC cavity, on the PPC lattice, on the air gap, and on the unpatterned gallium phosphide substrate. Polarization dependences of the cavity-coupled MoS2 emission show a more than 5 times stronger extracted PL intensity than the un-coupled emission, which indicates an underlying cavity mode Purcell enhancement of the MoS2 SE rate exceeding a factor of 70. PMID:24273329

  18. Control of spontaneous emission of an inverted Y-type atomic system coupled by three coherent fields

    SciTech Connect

    Qi Jianbing

    2009-10-15

    We investigate the spontaneous emission from an inverted Y-type atomic system coupled by three coherent fields. We use the Schroedinger equation to calculate the probability amplitudes of the wave function of the system and derive an analytical expression of the spontaneous emission spectrum to trace the origin of the spectral features. Quantum interference effects, such as the spectral line narrowing, spectrum splitting, and dark resonance, are observed. The number of spectral components, the spectral linewidth, and relative heights can be very different depending on the physical parameters. A variety of spontaneous emission spectral features can be controlled by the amplitude of the coupling fields and the preparation of the initial quantum state of the atom. We propose an ultracold atomic {sup 87}Rb system for experimental observation.

  19. Spontaneous emission control of single quantum dots by electrostatic tuning of a double-slab photonic crystal cavity

    NASA Astrophysics Data System (ADS)

    Midolo, Leonardo; Pagliano, Francesco; Hoang, Thang B.; Xia, Tian; van Otten, Frank W. M.; Li, Lianhe; Linfield, Edmund H.; Lermer, Matthias; Höfling, Sven; Fiore, Andrea

    2013-02-01

    We report the electromechanical control of spontaneous emission of single InAs quantum dots (QDs) embedded in wavelength-tunable double-membrane photonic crystal cavities (PCC). The tuning is achieved by modulating the distance between two parallel GaAs membranes by applying electrostatic forces across a p-i-n diode under reverse bias. The spontaneous emission rate of single dots has been modified by over a factor of ten, tuning the cavity reversibly between on- and off-resonant conditions without altering the emission energy of the dots. We also discuss a possible approach to integrate the double membrane structure with ridge waveguides, for the transmission of light within a photonic chip.

  20. Optical antenna enhanced spontaneous emission

    PubMed Central

    Eggleston, Michael S.; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C.

    2015-01-01

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ?200 THz optical frequency show a spontaneous emission intensity enhancement of 35 corresponding to a spontaneous emission rate speedup ?115, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ?2,500 spontaneous emission speedup at d ? 10 nm, proportional to 1/d2. Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, Io = q?|xo|/d, feeding the antenna-enhanced spontaneous emission, where q|xo| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency. PMID:25624503

  1. Controlling spontaneous emission with the local density of states of honeycomb photonic crystals

    NASA Astrophysics Data System (ADS)

    Tsai, Ya-Chih; Lin, Chien-Fan; Chang, Jui-Wen

    2009-05-01

    We calculated the local density of state for various positions in a photonic crystal of honeycomb lattice to study how the spontaneous emission rate of a radiating dipole is altered in the presence of the photonic crystal. The local density of states is found to be position-sensitive and its value can be enhanced or depressed relative to the density of states, depending on the location of the dipole. Our study shows that the density of states tends to underestimate the effect of a photonic crystal on the prohibition of light propagation, while on the contrary tends to overestimate the effect on the enhancement of light emission. The calculations also indicate that it is possible to tailor the spontaneous emission of an active medium by careful selecting its location in the photonic crystal. The results are helpful in determining the insertion location of the active medium and in evaluating the efficiency of active photonic crystal devices such as light-emitting diodes or lasers.

  2. Laser cooling without spontaneous emission.

    PubMed

    Corder, Christopher; Arnold, Brian; Metcalf, Harold

    2015-01-30

    This Letter reports the demonstration of laser cooling without spontaneous emission, and thereby addresses a significant controversy. It works by restricting the atom-light interaction to a time short compared to a cycle of absorption followed by natural decay. It is achieved by using the bichromatic force on an atomic transition with a relatively long excited state lifetime and a relatively short cooling time so that spontaneous emission effects are minimized. The observed width of the one-dimensional velocity distribution is reduced by ×2 thereby reducing the "temperature" by ×4. Moreover, our results comprise a compression in phase space because the spatial expansion of the atomic sample is limited. This accomplishment is of interest to direct laser cooling of molecules or in experiments where working space or time is limited. PMID:25679888

  3. Quenching of spontaneous emission through interference of incoherent pump processes

    SciTech Connect

    Kapale, Kishore T.; Scully, Marlan O.; Zhu Shiyao; Zubairy, M. Suhail

    2003-02-01

    We investigate the steady-state spontaneous emission of a V-type three-level atom, with the coherence between the two upper levels modified and controlled via incoherent pumping to a fourth auxiliary level. The external pumping gives us an easily controllable handle in manipulating the spontaneous emission to such an extent that, under certain conditions, complete quenching of spontaneous emission is possible. We also show that even the interference between the decay channels, which is considered a key requirement in spontaneous emission quenching through quantum interference, is not essential to achieve near 100% trapping and almost complete suppression of spontaneous emission. Thus we provide a scheme for spontaneous emission quenching which can be easily realized experimentally.

  4. InAs quantum boxes in GaAs/AlAs pillar microcavities: from spectroscopic investigations to spontaneous emission control

    NASA Astrophysics Data System (ADS)

    Grard, J. M.; Legrand, B.; Gayral, B.; Costard, E.; Sermage, B.; Kuszelewicz, R.; Barrier, D.; Thierry-Mieg, V.; Rivera, T.; Marzin, J. Y.

    1998-07-01

    GaAs/AlAs pillar microcavities containing an array of InAs quantum boxes in their core region have been fabricated by molecular beam epitaxy, electron-beam lithography and reactive ion etching. By placing this broadband light emitter in the cavity, we can probe precisely by photoluminescence the modal structure of the micropillars. After having validated this approach through the study of circular pillars, we address two important issues in context of spontaneous emission control. We show first that it is possible, by choosing an elliptical cross-section, to lift the polarization degeneracy of the fundamental mode of circular micropillars. By measuring Purcells factor for small pillars containing quantum boxes, we then highlight their potential for observing large cavity quantum electrodynamic effects in the weak coupling regime, which is confirmed by recent preliminary time-resolved experiments.

  5. Control of spontaneous emission from a microwave-field-coupled three-level{Lambda}-type atom in photonic crystals

    SciTech Connect

    Jiang, X. Q.; Zhang, B.; Sun, X. D.; Lu, Z. W.

    2011-05-15

    The spontaneous emission spectrum of a three-level {Lambda}-type atom driven by a microwave field was studied. For the two transitions coupled to the same modified reservoir, we discussed the influence of photonic band gap and Rabi frequency of the microwave field on the emission spectrum. The emission spectrum is given for different locations of the upper band-edge frequency. With the transition frequencies moving from outside the band gap to inside, the number of peaks decreases in the emission spectrum and the multipeak structure of spectral line is finally replaced by a strong non-Lorentzian shape. With increase of the Rabi frequency of the microwave field, we find the spectral line changes from a multipeak structure to a two-peak structure, originating from the inhibition of spontaneous emission for the corresponding decay channel.

  6. Dynamics of spontaneous otoacoustic emissions

    NASA Astrophysics Data System (ADS)

    Bergevin, Christopher; Salerno, Anthony

    2015-12-01

    Spontaneous otoacoustic emissions (SOAEs) have become a hallmark feature in modern theories of an `active' inner ear, given their numerous correlations to auditory function (e.g., threshold microstructure, neurophysiological tuning curves), near universality across tetrapod classes, and physiological correlates at the single hair cell level. However, while several different classes of nonlinear models exist that describe the mechanisms underlying SOAE generation (e.g., coupled limit-cycle oscillators, global standing waves), there is still disagreement as to precisely which biophysical concepts are at work. Such is further compounded by the idiosyncratic nature of SOAEs: Not all ears emit, and when present, SOAE activity can occur at seemingly arbitrary frequencies (though always within the most sensitive range of the audiogram) and in several forms (e.g., peaks, broad `baseline' plateaus). The goal of the present study was to develop new signal processing and stimulation techniques that would allow for novel features of SOAE activity to be revealed. To this end, we analyzed data from a variety of different species: human, lizard, and owl. First, we explored several strategies for examining SOAE waveforms in the absence of external stimuli to further ascertain what constitutes `self-sustained sinusoids' versus `filtered noise'. We found that seemingly similar peaks in the spectral domain could exhibit key differences in the time domain, which we interpret as providing critical information about the underlying oscillators and their coupling. Second, we introduced dynamic stimuli (swept-tones, tone bursts) at a range of levels, whose interaction with SOAEs could be visualized in the time-frequency domain. Aside from offering a readily accessible way to visualize many previously reported effects (e.g., entrainment, facilitation), we observed several new features such as subharmonic distortion generation and competing pulling/pushing effects when multiple tones were present. Furthermore, the tone burst data provide quantitative bounds on the dynamics of the relaxation oscillations. These data should provide new insights into how precisely how SOAE generators are related to (the more commonly measured) OAEs evoked via external stimuli and presumably speak to the robustness of the hair cell as the underlying basis for SOAE activity.

  7. Coherent control of cooperative spontaneous emission from two identical three-level atoms in a photonic crystal

    NASA Astrophysics Data System (ADS)

    Woldeyohannes, Mesfin; Idehenre, Ighodalo; Hardin, Tyler

    2015-08-01

    The coherent control of cooperative spontaneous emission from two identical non-overlapping three-level atoms in the V-configuration located within a photonic band gap (PBG) material with two resonant frequencies near the upper band edge of the PBG and confined to a region small in comparison to their radiation wavelengths but still greater than their atomic sizes is investigated. The dependencies of cooperative effects in which a photon emitted by one atom is reabsorbed by the other atom on the inter-atomic separation, on the initial state of the two-atom system, on the strength of the driving control laser field, and on the detuning of the atomic resonant frequencies from the upper band edge frequency is analyzed so as to identify the conditions for which these cooperative effects are enhanced or inhibited. Cooperative effects between atoms are shown to be influenced more by the PBG than by the nature of the atomic transitions involved. Excited state populations as well as coherences between excited levels are expressed in terms of time-dependent amplitudes which are shown to satisfy coupled integro-differential equations for which analytic solutions are derived under special conditions. Unlike for the case of one atom in a PBG where the fractional non-zero steady state populations on the excited levels as well as the coherence between the excited levels are constants independent of time, in the case of two atoms in PBG these quantities continuously oscillate as a manifestation of beating due to the continuous exchange between the two atoms of the photon trapped by the PBG. The values of these quantities as well as the amplitudes and frequencies of their oscillations depend of the parameters of the system, providing different ways of manipulating the system. The general formalism presented here is shown to recapture the special results of investigations of similar systems in free space when the non-Markovian memory kernels of the PBG are replaced by delta function dependent Markovian memory kernels.

  8. Blue shift of spontaneous emission in hyperbolic metamaterial

    PubMed Central

    Gu, Lei; Tumkur, T. U.; Zhu, G.; Noginov, M. A.

    2014-01-01

    Spontaneous emission is one of the most fundamental quantum phenomena in optics. Following the seminal work of Purcell and in agreement with the Fermi's Golden Rule, its rate can be controlled with the photonic density of states (PDOS). In recent years, this effect has been demonstrated in metamaterials with hyperbolic dispersion highly anisotropic composite materials, which have a broad-band singularity of the density of photonic states. At this time, we show that hyperbolic metamaterials can control spontaneous emission spectra as well. Experimentally, DCM laser dye has been embedded into lamellar metal/dielectric metamaterial. The observed 18?nm blue shift of emission is explained by strong dispersion of the density of photonic states. On the other hand, practically no spectral shift has been observed in the excitation spectra of the same dye. This suggests that the effect of PDOS on spontaneous emission is very different from its effect on excitation and absorption. PMID:24957679

  9. Ultrafast spontaneous emission source using plasmonic nanoantennas.

    PubMed

    Hoang, Thang B; Akselrod, Gleb M; Argyropoulos, Christos; Huang, Jiani; Smith, David R; Mikkelsen, Maiken H

    2015-01-01

    Typical emitters such as molecules, quantum dots and semiconductor quantum wells have slow spontaneous emission with lifetimes of 1-10?ns, creating a mismatch with high-speed nanoscale optoelectronic devices such as light-emitting diodes, single-photon sources and lasers. Here we experimentally demonstrate an ultrafast (<11?ps) yet efficient source of spontaneous emission, corresponding to an emission rate exceeding 90?GHz, using a hybrid structure of single plasmonic nanopatch antennas coupled to colloidal quantum dots. The antennas consist of silver nanocubes coupled to a gold film separated by a thin polymer spacer layer and colloidal core-shell quantum dots, a stable and technologically relevant emitter. We show an increase in the spontaneous emission rate of a factor of 880 and simultaneously a 2,300-fold enhancement in the total fluorescence intensity, which indicates a high radiative quantum efficiency of ?50%. The nanopatch antenna geometry can be tuned from the visible to the near infrared, providing a promising approach for nanophotonics based on ultrafast spontaneous emission. PMID:26212857

  10. Ultrafast spontaneous emission source using plasmonic nanoantennas

    NASA Astrophysics Data System (ADS)

    Hoang, Thang B.; Akselrod, Gleb M.; Argyropoulos, Christos; Huang, Jiani; Smith, David R.; Mikkelsen, Maiken H.

    2015-07-01

    Typical emitters such as molecules, quantum dots and semiconductor quantum wells have slow spontaneous emission with lifetimes of 1-10 ns, creating a mismatch with high-speed nanoscale optoelectronic devices such as light-emitting diodes, single-photon sources and lasers. Here we experimentally demonstrate an ultrafast (<11 ps) yet efficient source of spontaneous emission, corresponding to an emission rate exceeding 90 GHz, using a hybrid structure of single plasmonic nanopatch antennas coupled to colloidal quantum dots. The antennas consist of silver nanocubes coupled to a gold film separated by a thin polymer spacer layer and colloidal core-shell quantum dots, a stable and technologically relevant emitter. We show an increase in the spontaneous emission rate of a factor of 880 and simultaneously a 2,300-fold enhancement in the total fluorescence intensity, which indicates a high radiative quantum efficiency of ~50%. The nanopatch antenna geometry can be tuned from the visible to the near infrared, providing a promising approach for nanophotonics based on ultrafast spontaneous emission.

  11. Ultrafast spontaneous emission source using plasmonic nanoantennas

    PubMed Central

    Hoang, Thang B.; Akselrod, Gleb M.; Argyropoulos, Christos; Huang, Jiani; Smith, David R.; Mikkelsen, Maiken H.

    2015-01-01

    Typical emitters such as molecules, quantum dots and semiconductor quantum wells have slow spontaneous emission with lifetimes of 1–10 ns, creating a mismatch with high-speed nanoscale optoelectronic devices such as light-emitting diodes, single-photon sources and lasers. Here we experimentally demonstrate an ultrafast (<11 ps) yet efficient source of spontaneous emission, corresponding to an emission rate exceeding 90 GHz, using a hybrid structure of single plasmonic nanopatch antennas coupled to colloidal quantum dots. The antennas consist of silver nanocubes coupled to a gold film separated by a thin polymer spacer layer and colloidal core–shell quantum dots, a stable and technologically relevant emitter. We show an increase in the spontaneous emission rate of a factor of 880 and simultaneously a 2,300-fold enhancement in the total fluorescence intensity, which indicates a high radiative quantum efficiency of ∼50%. The nanopatch antenna geometry can be tuned from the visible to the near infrared, providing a promising approach for nanophotonics based on ultrafast spontaneous emission. PMID:26212857

  12. Quenching of spontaneous emission coefficients in plasmas

    SciTech Connect

    Chung, Y.; Lemaire, P.; Suckewer, S.

    1987-09-01

    We have observed changing Einstein coefficients of spontaneous emission as a function of electron density in CO/sub 2/ laser-produced plasmas. These measurements are based on the intensity branching ratio of CIV lines 5801 to 5812 A and 312.41 to 312.46 A which share a common upper level. Similar observations for CIII lines are also discussed. 12 refs., 3 figs.

  13. Modified spontaneous emission in nanophotonic structures

    NASA Astrophysics Data System (ADS)

    Pelton, Matthew

    2015-07-01

    Spontaneous emission is not an inherent property of a luminescent material; rather, it arises due to interaction between the material and its local electromagnetic environment. Changing the environment can thus alter the emission rate, with potential applications in sensing, integrated photonics and solar energy conversion. Significant increases in emission rate require an optical resonator that stores light in as small a volume as possible, for as long as possible. This is currently achieved using two main systems: photonic crystal microcavities and plasmonic metal nanoparticles. These two systems have largely been developed independently, but the underlying physical mechanisms are the same. Comparing the two provides insight into emission modification and illustrates some of the subtleties involved in interpreting experimental results.

  14. Competition between coherent emission and broadband spontaneous emission in the quantum free electron laser

    SciTech Connect

    Robb, G. R. M.; Bonifacio, R.

    2013-03-15

    We extend previous analyses of spontaneous emission in a quantum free electron laser (QFEL) and competition between spontaneous and coherent QFEL emission to include a broad distribution of photon frequencies and momenta appropriate for spontaneous undulator radiation. We show that although the predictions of monochromatic and broadband models predict different electron momentum distributions for the quantum regime due to spontaneous emission alone after many photon emissions, the inclusion of broadband spontaneous emission has a negligible effect on the competition between spontaneous and coherent emission in the QFEL. Numerical results from both models are well described by the same condition for the threshold/critical value of spontaneous emission rate.

  15. Excess spontaneous-emission factor in unstable-resonator lasers.

    PubMed

    Yao, G; Chen, Y C; Harding, C M; Sherrick, S M; Dalby, R J; Waters, R G; Largent, C

    1992-09-01

    The spontaneous-emission factor in an unstable-resonator semiconductor laser is enhanced by more than 2 orders of magnitude compared with that of a Fabry-Perot semiconductor laser having the same volume. A clear linkage has been observed among the spontaneous-emission factor, the waveguiding property, and the width of the lasing spectral envelope. PMID:19798135

  16. Coherent and spontaneous emission in the quantum free electron laser

    SciTech Connect

    Robb, G. R. M.; Bonifacio, R.

    2012-07-15

    We present an analysis of quantum free electron laser (QFEL) dynamics including the effects of spontaneous emission. The effects of spontaneous emission are undesirable for coherent short-wave generation using FELs and have been shown in previous studies to limit the capabilities of classical self amplified spontaneous emission (SASE)-FELs at short wavelengths {approx}1 A due to growth of electron beam energy spread. As one of the attractive features of the QFEL is its potential as a relatively compact coherent x-ray source, it is important to understand the role of spontaneous emission, but to date there has not been a model which is capable of consistently describing the dynamics of both coherent FEL emission and incoherent spontaneous emission. In this paper, we present such a model, and use it to show that the limitations imposed by spontaneous emission on coherent FEL operation are significantly different in the quantum regime to those in the classical regime. An example set of parameters constituting a QFEL using electron and laser parameters which satisfy the condition for neglect of spontaneous emission during coherent QFEL emission is presented.

  17. Controlling spontaneous-emission noise in measurement-based feedback cooling of a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Hush, M. R.; Szigeti, S. S.; Carvalho, A. R. R.; Hope, J. J.

    2013-11-01

    Off-resonant optical imaging is a popular method for continuous monitoring of a Bose-Einstein condensate. However, the disturbance caused by scattered photons places a serious limitation on the lifetime of such continuously monitored condensates. In this paper, we demonstrate that a new choice of feedback control can overcome the heating effects of the measurement backaction. In particular, we show that the measurement backaction caused by off-resonant optical imaging is a multi-mode quantum-field effect, as the entire heating process is not seen in single-particle or mean-field models of the system. Simulating such continuously monitored systems is possible with the number-phase Wigner particle filter, which currently gives both the highest precision and largest timescale simulations amongst competing methods. It is a hybrid between the leading techniques for simulating non-equilibrium dynamics in condensates and particle filters for simulating high-dimensional non-Gaussian filters in the field of engineering. The new control scheme will enable long-term continuous measurement and feedback on one of the leading platforms for precision measurement and the simulation of quantum fields, allowing for the possibility of single-shot experiments, adaptive measurements and robust state-preparation and manipulation.

  18. Single photon production by rephased amplified spontaneous emission

    NASA Astrophysics Data System (ADS)

    Stevenson, R. N.; Hush, M. R.; Carvalho, A. R. R.; Beavan, S. E.; Sellars, M. J.; Hope, J. J.

    2014-03-01

    The production of single photons using rephased amplified spontaneous emission is examined. This process produces single photons on demand with high efficiency by detecting the spontaneous emission from an atomic ensemble, then applying a population-inverting pulse to rephase the ensemble and produce a photon echo of the spontaneous emission events. The theoretical limits on the efficiency of the production are determined for several variants of the scheme. For an ensemble of uniform optical density, generating the initial spontaneous emission and its echo using transitions of different strengths is shown to produce single photons at 70% efficiency, limited by reabsorption. Tailoring the spatial and spectral density of the atomic ensemble is then shown to prevent reabsorption of the rephased photon, resulting in emission efficiency near unity.

  19. Modified spontaneous emissions of europium complex in weak PMMA opals.

    PubMed

    Wang, Wei; Song, Hongwei; Bai, Xue; Liu, Qiong; Zhu, Yongsheng

    2011-10-28

    Engineering spontaneous emission by means of photonic crystals (PHC) is under extensive study. However PHC modification of line emissions of rare earth (RE) ions has not been thoroughly understood, especially in cases of weak opal PHCs and while emitters are well dispersed into dielectric media. In this study, poly-methyl methacrylate (PMMA) opal PHCs containing uniformly dispersed europium chelate were fabricated with finely controlled photonic stop band (PSB) positions. Measurements of luminescent dynamics and angle resolved/integrated emission spectra as well as numerical calculations of total densities of states (DOS) were performed. We determined that in weak opals, the total spontaneous emission rate (SER) of ?(5)D(0)-(7)F(J) for Eu(3+) was independent of PSB positions but was higher than that of the disordered powder sample, which was attributed to higher effective refractive indices in the PHC rather than PSB effect. Branch SER of (5)D(0)-(7)F(2) for Eu(3+) in the PHCs, on the other hand, was spatially redistributed, suppressed or enhanced in directions of elevated or reduced optical modes, keeping the angle-integrated total unchanged. All the results are in agreement with total DOS approximation. Our paper addressed two unstudied issues regarding modified narrow line emission in weak opal PHCs: firstly whether PSB could change the SER of emitters and whether there exist, apart from PSB, other reasons to change SERs; secondly, while directional enhancement and suppression by PSB has been confirmed, whether the angle-integrated overall effect is enhancing or suppressing. PMID:21938288

  20. Quantitative analysis of directional spontaneous emission spectra from light sources in photonic crystals

    SciTech Connect

    Nikolaev, Ivan S.; Lodahl, Peter; Vos, Willem L.

    2005-05-15

    We have performed angle-resolved measurements of spontaneous-emission spectra from laser dyes and quantum dots in opal and inverse opal photonic crystals. Pronounced directional dependencies of the emission spectra are observed: angular ranges of strongly reduced emission adjoin with angular ranges of enhanced emission. It appears that emission from embedded light sources is affected both by the periodicity and by the structural imperfections of the crystals: the photons are Bragg diffracted by lattice planes and scattered by unavoidable structural disorder. Using a model comprising diffuse light transport and photonic band structure, we quantitatively explain the directional emission spectra. This work provides detailed understanding of the transport of spontaneously emitted light in real photonic crystals, which is essential in the interpretation of quantum optics in photonic-band-gap crystals and for applications wherein directional emission and total emission power are controlled.

  1. Tunable Casimir-Polder Forces and Spontaneous Emission Rates

    NASA Astrophysics Data System (ADS)

    Rosa, Felipe; Kort-Kamp, Wilton; Pinheiro, Felipe; Cysne, Tarik; Oliver, Diego; Farina, Carlos

    2015-03-01

    We investigate the dispersive Casimir-Polder interaction between a Rubidium atom and a graphene sheet subjected to an external magnetic field B. We demonstrate that this concrete physical system allows for a high degree of control of dispersive interactions at micro and nanoscales. Indeed, we show that the application of an external magnetic field can induce a 80 % reduction of the Casimir-Polder energy relative to its value without the field. We also show that sharp discontinuities emerge in the Casimir-Polder interaction energy for certain values of the applied magnetic field at low temperatures. In addition, we also show that atomic spontaneous emission rates can be greatly modified by the action of the magnetic field, with an order of magnitude enhancement or suppression depending on the dipole's moment orientation.

  2. Reversible Modulation of Spontaneous Emission by Strain in Silicon Nanowires

    PubMed Central

    Shiri, Daryoush; Verma, Amit; Selvakumar, C. R.; Anantram, M. P.

    2012-01-01

    We computationally study the effect of uniaxial strain in modulating the spontaneous emission of photons in silicon nanowires. Our main finding is that a one to two orders of magnitude change in spontaneous emission time occurs due to two distinct mechanisms: (A) Change in wave function symmetry, where within the direct bandgap regime, strain changes the symmetry of wave functions, which in turn leads to a large change of optical dipole matrix element. (B) Direct to indirect bandgap transition which makes the spontaneous photon emission to be of a slow second order process mediated by phonons. This feature uniquely occurs in silicon nanowires while in bulk silicon there is no change of optical properties under any reasonable amount of strain. These results promise new applications of silicon nanowires as optoelectronic devices including a mechanism for lasing. Our results are verifiable using existing experimental techniques of applying strain to nanowires. PMID:22708056

  3. QED (quantum-electrodynamical) theory of excess spontaneous emission noise

    SciTech Connect

    Milonni, P.W.

    1990-01-01

    The results of a quantum-electrodynamical theory of excess spontaneous emission noise in lossy resonators will be presented. The Petermann K factor'' does not enter into the spontaneous emission rate of a single atom in the cavity. The QED theory allows different interpretations of the K factor, and we use this fact to justify semiclassical analyses and to provide in one example a simple derivation of K in terms of the amplification of the quantum vacuum field entering the resonator through its mirrors. 17 refs.

  4. Spontaneous and stimulated emission tuning characteristics of a Josephson junction in a microcavity

    NASA Astrophysics Data System (ADS)

    Joseph, Andrea T.; Whiting, Robin; Andrews, Roger

    2004-11-01

    We have investigated theoretically the tuning characteristics of a Josephson junction within a microcavity for one-photon spontaneous emission and for one-photon and two-photon stimulated emission. For spontaneous emission, we have established the linear relationship between the magnetic induction and the voltage needed to tune the system to emit at resonant frequencies. For stimulated emission, we have found an oscillatory dependence of the emission rate on the initial Cooper pair phase difference and the phase of the applied field. Under specific conditions, we have also calculated the values of the applied radiation amplitude for the first few emission maxima of the system and for the first five junction-cavity resonances for each process. Because the emission of photons can be controlled, it may be possible to use such a system to produce photons on demand. Such sources will have applications in the fields of quantum cryptography, communications, and computation.

  5. Spontaneous Radio Frequency Emissions from Natural Aurora. Chapter 4

    NASA Technical Reports Server (NTRS)

    LaBelle, J.

    2009-01-01

    At high latitudes, suitably sensitive radio experiments tuned below 5 MHz detect up to three types of spontaneous radio emissions from the Earth s ionosphere. In recent years, ground-based and rocket-borne experiments have provided strong evidence for theoretical explanations of the generation mechanism of some of these emissions, but others remain unexplained. Achieving a thorough understanding of these ionospheric emissions, accessible to ground-based experiments, will not only bring a deeper understanding of Earth s radio environment and the interactions between waves and particles in the ionosphere but also shed light on similar spontaneous emissions occurring elsewhere in Earth s environment as well as other planetary and stellar atmospheres.

  6. Amplified spontaneous emission in solar-pumped iodine laser

    NASA Technical Reports Server (NTRS)

    Cho, Yong S.; Hwang, In H.; Han, Kwang S.; Lee, Ja H.

    1992-01-01

    The amplified spontaneous emission (ASE) from a long pulse, solar-simulating radiation pumped iodine laser amplifier is studied. The ASE threshold pump intensity is almost proportional to the inverse of the laser gain length when the gas pressure is constant in the laser tube.

  7. Spontaneous otoacoustic emissions in heterosexuals, homosexuals, and bisexuals.

    PubMed

    McFadden, D; Pasanen, E G

    1999-04-01

    Click-evoked otoacoustic emissions (CEOAEs) were previously shown to be significantly less strong in homosexual and bisexual females than in heterosexual females. Here it is reported that the spontaneous otoacoustic emissions (SOAEs) of those same 60 homosexual and bisexual females were less numerous and weaker than those in 57 heterosexual females. That is, the SOAEs of the homosexual and bisexual females were intermediate to those of heterosexual females and heterosexual males. The SOAE and CEOAE data both suggest that the cochleas of homosexual and bisexual females have been partially masculinized, possibly as part of some prenatal processes that also masculinized whatever brain structures are responsible for sexual orientation. For males of all sexual orientation, the SOAEs were less numerous and weaker than for the females, and there were no significant differences among the 56 heterosexual, 51 homosexual, and 11 bisexual males. All subjects passed a hearing screening test. When all SOAEs above 3000 Hz were excluded (as a control against incipient, undetected hearing loss) the same results were obtained as with the full range of data (550-9000 Hz). The differential use of oral contraceptives by the heterosexual and nonheterosexual females also could not explain the differences in their OAEs. PMID:10212421

  8. A hybrid nanoantenna for highly enhanced directional spontaneous emission

    SciTech Connect

    Chou, R. Yuanying; Lu, Guowei Shen, Hongming; He, Yingbo; Cheng, Yuqing; Perriat, Pascal; Martini, Matteo; Tillement, Olivier; Gong, Qihuang

    2014-06-28

    Spontaneous emission modulated by a hybrid plasmonic nanoantenna has been investigated by employing finite-difference time-domain method. The hybrid nanoantenna configurations constituted by a gap hot-spot and of a plasmonic corrugated grating and a metal reflector sandwiching a SiO{sub 2} thin layer which appears promising for high spontaneous emission enhancement devices. Simulation assays show that the coupling between the gap-antenna and plasmonic corrugations reaches an ultra-high near-field enhancement factor in the excitation process. Moreover, concerning the emission process, the corrugations concentrate the far-field radiated power within a tiny angular volume, offering unprecedented collection efficiency. In the past decades, many kinds of optical antennas have been proposed and optimized to enhance single molecule detection. However, the excitation enhancement effect for single individual or dimmer plasmonic nanostructure is limited due to intrinsic nonradiative decay of the nanoparticle plasmon and quantum tunneling effect. The proposed hybrid configuration overwhelms the enhancement limit of single individual plasmonic structure. The findings provide an insight into spontaneous emission high enhancement through integrating the functions of different metallic nanostructures.

  9. Spontaneous emission of the non-Wiener type

    SciTech Connect

    Basharov, A. M.

    2011-09-15

    The spontaneous emission of a quantum particle and superradiation of an ensemble of identical quantum particles in a vacuum electromagnetic field with zero photon density are examined under the conditions of significant Stark particle and field interaction. New fundamental effects are established: suppression of spontaneous emission by the Stark interaction, an additional 'decay' shift in energy of the decaying level as a consequence of Stark interaction unrelated to the Lamb and Stark level shifts, excitation conservation phenomena in a sufficiently dense ensemble of identical particles and suppression of superradiaton in the decay of an ensemble of excited quantum particles of a certain density. The main equations describing the emission processes under conditions of significant Stark interaction are obtained in the effective Hamiltonian representation of quantum stochastic differential equations. It is proved that the Stark interaction between a single quantum particle and a broadband electromagnetic field is represented as a quantum Poisson process and the stochastic differential equations are of the non-Wiener (generalized Langevin) type. From the examined case of spontaneous emission of a quantum particle, the main rules are formulated for studying open systems in the effective Hamiltonian representation.

  10. A hybrid nanoantenna for highly enhanced directional spontaneous emission

    NASA Astrophysics Data System (ADS)

    Chou, R. Yuanying; Lu, Guowei; Shen, Hongming; He, Yingbo; Cheng, Yuqing; Perriat, Pascal; Martini, Matteo; Tillement, Olivier; Gong, Qihuang

    2014-06-01

    Spontaneous emission modulated by a hybrid plasmonic nanoantenna has been investigated by employing finite-difference time-domain method. The hybrid nanoantenna configurations constituted by a gap hot-spot and of a plasmonic corrugated grating and a metal reflector sandwiching a SiO2 thin layer which appears promising for high spontaneous emission enhancement devices. Simulation assays show that the coupling between the gap-antenna and plasmonic corrugations reaches an ultra-high near-field enhancement factor in the excitation process. Moreover, concerning the emission process, the corrugations concentrate the far-field radiated power within a tiny angular volume, offering unprecedented collection efficiency. In the past decades, many kinds of optical antennas have been proposed and optimized to enhance single molecule detection. However, the excitation enhancement effect for single individual or dimmer plasmonic nanostructure is limited due to intrinsic nonradiative decay of the nanoparticle plasmon and quantum tunneling effect. The proposed hybrid configuration overwhelms the enhancement limit of single individual plasmonic structure. The findings provide an insight into spontaneous emission high enhancement through integrating the functions of different metallic nanostructures.

  11. Are Einstein's transition probabilities for spontaneous emission constant in plasmas?

    NASA Technical Reports Server (NTRS)

    Griem, H. R.; Huang, Y. W.; Wang, J.-S.; Moreno, J. C.

    1991-01-01

    An investigation is conducted with a ruby laser to experimentally confirm the quenching of spontaneous emission coefficients and propose a mechanism for the phenomenon. Results of previous experiments are examined to determine the consistency and validity of interpretations of the spontaneous emissions. For the C IV 3s-3p and 2s-3p transitions, the line-intensity ratios are found to be dependent on the separation of the laser from the target. Density gradients and Stark broadening are proposed to interpret the results in a way that does not invalidate the Einstein A values. The interpretation is extended to C III and N V, both of which demonstrate similar changes in A values in previous experiments. The apparent quenching of Ar II by photon collisions is explained by Rabi oscillations and power broadening in the argon-ion laser cavity. It is concluded that the changes in A values cannot result from dense plasma effects.

  12. Amplified spontaneous emission in a Ti:sapphire regenerative amplifier

    NASA Astrophysics Data System (ADS)

    Ivanov, Vladimir V.; Maksimchuk, Anatoly; Mourou, Gerard

    2003-12-01

    Amplified spontaneous emission power and contrast ratio in a linear miltipass Ti:sapphire regenerative amplifier with a wavelength centered at 1054 nm are calculated and measured. It is shown that the passive losses of a seed pulse and the losses in coupling to the regenerative amplifier cavity mode degrade the intensity contrast ratio to 10-6-10-7. The advantage of an optical parametric chirped pulse amplifier with respect to the contrast ratio is discussed.

  13. 2-.mu.m fiber amplified spontaneous emission (ASE) source

    NASA Technical Reports Server (NTRS)

    Jiang, Shibin (Inventor); Wu, Jianfeng (Inventor); Geng, Jihong (Inventor)

    2007-01-01

    A 2-.mu.m fiber Amplified Spontaneous Emission (ASE) source provides a wide emission bandwidth and improved spectral stability/purity for a given output power. The fiber ASE source is formed from a heavy metal oxide multicomponent glass selected from germanate, tellurite and bismuth oxides and doped with high concentrations, 0.5-15 wt. %, thulium oxides (Tm.sub.2O.sub.3) or 0.1-5 wt% holmium oxides (Ho.sub.2O.sub.3) or mixtures thereof. The high concentration of thulium dopants provide highly efficient pump absorption and high quantum efficiency. Co-doping of Tm and Ho can broaden the ASE spectrum.

  14. Spontaneous UV-emission from nitrogen and rare-gas halogen excimers in a fast-flowing crossed-beam plasma-mixing device for pollution control

    SciTech Connect

    Kirkici, H.; Kralovec, J.

    1995-12-31

    Air pollution, water (under ground or ground), and soil contamination have become major issues with increasing industrialization. In addition to conventional incineration techniques, non-thermal plasma techniques and photolysis have been demonstrated to be very powerful tools converting pollutants into harmless chemicals. The use of excimer lamps for pollution control provides an important advantage. Emission spectrum of excimer molecules depends on the type of the gas molecules in the discharge tube forming the particular excimer molecule. Therefore, by choosing the adequate gas mixture, an emission may be found which coincides with the absorption maximum of the pollutant. One other advantage of using excimer lamps is the high efficiency of these lamps in the UV region compared to the conventional lamps. The photon energy efficiency of an excimer lamp can be as high as 10% depending on the design. The authors have developed the technique of fast plasma mixing which overcomes some of the disadvantages of excimer generation in a glow discharge, or in an electron beam sustained gas discharge, and offers an effective way to generate continuous wave UV radiation. This technique utilizes near resonant energy and charge transfer from metastable rare gas atoms and ions to molecules. A fast-flowing crossed-beam plasma mixing device can be utilized to obtain high efficiency UV lamps for industrial use. In this work, basic concepts of the crossed-beam plasma-mixing device operation are presented.

  15. Directional and enhanced spontaneous emission with a corrugated metal probe

    NASA Astrophysics Data System (ADS)

    Shen, Hongming; Lu, Guowei; He, Yingbo; Cheng, Yuqing; Liu, Haitao; Gong, Qihuang

    2014-06-01

    A three-dimensional corrugated metal tapered probe with surface corrugated gratings at the tip apex is proposed and investigated theoretically, which leads to an obvious emission beaming effect of spontaneous emission from a single emitter near the probe. In contrast with conventional apertureless metal probes, where only the enhancement of an optical near-field is concerned, the corrugated probe is able to manipulate local excitation intensity and far-field emission direction simultaneously. The angular emission from a single dipole source, being placed close to the corrugated probe, falls into a cone with a maximum directivity angle of +/-11.6°, which improves the collection efficiency 25-fold. Such a probe simultaneously increases the localized field intensity to about twice as strong as the conventional bare tip. In addition, the radiation pattern is sensitive to the working wavelength and the dipole to tip-apex separation. These findings make a promising route to the development of plasmonic spontaneous emission manipulation based on corrugated tapered antenna--for instance, tip-enhanced spectroscopy, single-molecule sensing, and single-photon source .

  16. Amplified spontaneous emission in the spiropyran-biopolymer based system

    NASA Astrophysics Data System (ADS)

    Mysliwiec, Jaroslaw; Sznitko, Lech; Bartkiewicz, Stanislaw; Miniewicz, Andrzej; Essaidi, Zacaria; Kajzar, Francois; Sahraoui, Bouchta

    2009-06-01

    Amplified spontaneous emission (ASE) phenomenon in the 6-nitro-1',3',3'-trimethylspiro[2H-1-benzopyran-2,2'-indolin] organic dye dispersed in a solid matrix has been observed. The biopolymer system deoxyribonucleic acid blended with cationic surfactant molecule cetyltrimethyl-ammonium chloride served as a matrix. ASE appeared under sample excitation by UV light pulses (? =355 nm) coming from nanosecond or picosecond neodymium doped yttrium aluminum garnet lasers and has been reinforced with green (? =532 nm) light excitation followed UV light pulse. The ASE characteristics in function of different excitation pulse energies as well as signal gain were measured.

  17. Emission of photons in spontaneous fission of {sup 252}Cf

    SciTech Connect

    van der Ploeg, H.; Bacelar, J.C.S.; Buda, A.; Laurens, C.R.; van der Woude, A.; Gaardhoje, J.J.; Zelazny, Z.; van `t Hof, G.; Kalantar-Nayestanaki, N.

    1995-10-01

    High energy photon emission accompanying the spontaneous fission of {sup 252}Cf is measured for different mass splits. The photon yields up to an energy of 20 MeV are obtained at several angles relative to the fission direction. Statistical model calculations are used to interpret the data. The photon yield is found to be very sensitive to the initial excitation energy sharing among the daughter nuclei and to their level density parameters. Using experimentally extracted level densities obtained from neutron evaporation measurements, the photon yield is well described by calculations for all mass splits.

  18. Spontaneous Radiation Emission from Short, High Field Strength Insertion Devices

    SciTech Connect

    Geoffrey Krafft

    2005-09-15

    Since the earliest papers on undulaters were published, it has been known how to calculate the spontaneous emission spectrum from ''short'' undulaters when the magnetic field strength parameter is small compared to unity, or in ''single'' frequency sinusoidal undulaters where the magnetic field strength parameter is comparable to or larger than unity, but where the magnetic field amplitude is constant throughout the undulater. Fewer general results have been obtained in the case where the insertion device is both short, i.e., the magnetic field strength parameter changes appreciably throughout the insertion device, and the magnetic field strength is high enough that ponderomotive effects, radiation retardation, and harmonic generation are important physical phenomena. In this paper a general method is presented for calculating the radiation spectrum for short, high-field insertion devices. It is used to calculate the emission from some insertion device designs of recent interest.

  19. Amplified spontaneous emission properties of semiconducting organic materials.

    PubMed

    Calzado, Eva M; Boj, Pedro G; Díaz-García, María A

    2010-01-01

    This paper aims to review the recent advances achieved in the field of organic solid-state lasers with respect to the usage of semiconducting organic molecules and oligomers in the form of thin films as active laser media. We mainly focus on the work performed in the last few years by our research group. The amplified spontaneous emission (ASE) properties, by optical pump, of various types of molecules doped into polystyrene films in waveguide configuration, are described. The various systems investigated include N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD), several perilenediimide derivatives (PDIs), as well as two oligo-phenylenevinylene derivatives. The ASE characteristics, i.e., threshold, emission wavelength, linewidth, and photostability are compared with that of other molecular materials investigated in the literature. PMID:20640167

  20. Amplified Spontaneous Emission Properties of Semiconducting Organic Materials

    PubMed Central

    Calzado, Eva M.; Boj, Pedro G.; Daz-Garca, Mara A.

    2010-01-01

    This paper aims to review the recent advances achieved in the field of organic solid-state lasers with respect to the usage of semiconducting organic molecules and oligomers in the form of thin films as active laser media. We mainly focus on the work performed in the last few years by our research group. The amplified spontaneous emission (ASE) properties, by optical pump, of various types of molecules doped into polystyrene films in waveguide configuration, are described. The various systems investigated include N,N?-bis(3-methylphenyl)-N,N?-diphenylbenzidine (TPD), several perilenediimide derivatives (PDIs), as well as two oligo-phenylenevinylene derivatives. The ASE characteristics, i.e., threshold, emission wavelength, linewidth, and photostability are compared with that of other molecular materials investigated in the literature. PMID:20640167

  1. TRASER - Total Reflection Amplification of Spontaneous Emission of Radiation

    PubMed Central

    Zachary, Christopher B.; Gustavsson, Morgan

    2012-01-01

    Background and Objective Light and lasers in medical therapy have made dramatic strides since their invention five decades ago. However, the manufacture of lasers can be complex and expensive which often makes treatments limited and costly. Further, no single laser will provide the correct parameters to treat all things. Hence, laser specialists often need multiple devices to practice their specialty. A new concept is described herein that has the potential to replace many lasers and light sources with a single tunable device. Study Design/Material and Methods This device amplifies spontaneous emission of radiation by capturing and retaining photons through total internal reflection, hence the acronym Total Reflection Amplification of Spontaneous Emission of Radiation, or TRASER. Results Specific peaks of light can be produced in a reproducible manner with high peak powers of variable pulse durations, a large spot size, and high repetition rate. Conclusion Considering the characteristics and parameters of Traser technology, it is possible that this one device would likely be able to replace the pulsed dye laser and many other light based systems. PMID:22558261

  2. Experimental realization of light with time-separated correlations by rephasing amplified spontaneous emission.

    PubMed

    Ledingham, Patrick M; Naylor, William R; Longdell, Jevon J

    2012-08-31

    Amplified spontaneous emission is a common noise source in active optical systems, it is generally seen as being an incoherent process. Here we excite an ensemble of rare earth ion dopants in a solid with a ? pulse, resulting in amplified spontaneous emission. The application of a second ? pulse leads to a coherent echo of the amplified spontaneous emission that is correlated in both amplitude and phase. For small optical thicknesses, we see evidence that the amplified spontaneous emission and its echo are entangled. PMID:23002832

  3. Theory of Spontaneous Emission Noise in Multisection Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Loudon, Rodney; Ramoo, Desi; Adams, Michael J.

    2005-08-01

    Calculations of spontaneous emission noise in semiconductor lasers are mainly based on a fundamental theory developed by Henry in 1986, which is useful for simple systems, together with a formulation in terms of transfer matrices by Makino and others, which facilitates application of the theory to more complicated multisection systems. The aim of this review is to present a unified account of this theoretical work in a transparent form intended to encourage its further use in complex systems. The opportunity is taken to strengthen the existing theory by including the effects of differing optical wave vectors in different sections and the consequent reflections at interfaces, which are important in some applications. Sample calculations are presented for a range of systems with one, two, three, and four sections and the predictions compared with other theoretical and experimental results.

  4. Randomness generation based on spontaneous emissions of lasers

    NASA Astrophysics Data System (ADS)

    Zhou, Hongyi; Yuan, Xiao; Ma, Xiongfeng

    2015-06-01

    Random numbers play a key role in information science, especially in cryptography. Based on the probabilistic nature of quantum mechanics, quantum random number generators can produce genuine randomness. In particular, random numbers can be produced from laser phase fluctuations with a very high speed, typically in the Gbps regime. In this work, by developing a physical model, we investigate the origin of the randomness in quantum random number generators based on laser phase fluctuations. We show how the randomness essentially stems from spontaneous emissions. The laser phase fluctuation can be quantitatively evaluated from basic principles and qualitatively explained by the Brownian motion model. After taking account of practical device precision, we show that the randomness generation speed is limited by the finite resolution of detection devices. Our result also provides the optimal experiment design in order to achieve the maximum generation speed.

  5. High spectral density transmission emulation using amplified spontaneous emission noise.

    PubMed

    Elson, Daniel J; Galdino, Lidia; Maher, Robert; Killey, Robert I; Thomsen, Benn C; Bayvel, Polina

    2016-01-01

    We demonstrate the use of spectrally shaped amplified spontaneous emission (SS-ASE) noise for wideband channel loading in the investigation of nonlinear transmission limits in wavelength-division multiplexing transmission experiments using Nyquist-spaced channels. The validity of this approach is explored through statistical analysis and experimental transmission of Nyquist-spaced 10GBaud polarization-division multiplexing (PDM) quadrature phase-shift keying and PDM-16-ary quadrature amplitude modulation (QAM) channels, co-propagated with SS-ASE over single mode fiber. It is shown that this technique, which is simpler to implement than a fully modulated comb of channels, is valid for distances exceeding 240km for PDM-16QAM with dispersion of 16ps/nm/km, yields a good agreement with theory, and provides a conservative measure of system performance. PMID:26696160

  6. Sex and Ear Differences in Spontaneous and Click-Evoked Otoacoustic Emissions in Young Adults

    ERIC Educational Resources Information Center

    Snihur, Adrian W. K.; Hampson, Elizabeth

    2011-01-01

    Effects of sex and handedness on the production of spontaneous and click-evoked otoacoustic emissions (OAEs) were explored in a non-hearing impaired population (ages 17-25 years). A sex difference in OAEs, either produced spontaneously (spontaneous OAEs or SOAEs) or in response to auditory stimuli (click-evoked OAEs or CEOAEs) has been reported in

  7. Sex and Ear Differences in Spontaneous and Click-Evoked Otoacoustic Emissions in Young Adults

    ERIC Educational Resources Information Center

    Snihur, Adrian W. K.; Hampson, Elizabeth

    2011-01-01

    Effects of sex and handedness on the production of spontaneous and click-evoked otoacoustic emissions (OAEs) were explored in a non-hearing impaired population (ages 17-25 years). A sex difference in OAEs, either produced spontaneously (spontaneous OAEs or SOAEs) or in response to auditory stimuli (click-evoked OAEs or CEOAEs) has been reported in…

  8. Spontaneous emission noise in long-range surface plasmon polariton waveguide based optical gyroscope.

    PubMed

    Wang, Yang-Yang; Zhang, Tong

    2014-01-01

    Spontaneous emission noise is an important limit to the performance of active plasmonic devices. Here, we investigate the spontaneous emission noise in the long-range surface plasmon-polariton waveguide based optical gyroscope. A theoretical model of the sensitivity is established to study the incoherent multi-beam interference of spontaneous emission in the gyroscope. Numerical results show that spontaneous emission produces a drift in the transmittance spectra and lowers the signal-to-noise-ratio of the gyroscope. It also strengthens the shot noise to be the main limit to the sensitivity of the gyroscope for high propagation loss. To reduce the negative effects of the spontaneous emission noise on the gyroscope, an external feedback loop is suggested to estimate the drift in the transmittance spectra and therefor enhance the sensitivity. Our work lays a foundation for the improvement of long-range surface plasmon-polariton gyroscope and paves the way to its practical application. PMID:25234712

  9. Vacuum field energy and spontaneous emission in anomalously dispersive cavities

    SciTech Connect

    Bradshaw, Douglas H.; Di Rosa, Michael D.

    2011-05-15

    Anomalously dispersive cavities, particularly white-light cavities, may have larger bandwidth to finesse ratios than their normally dispersive counterparts. Partly for this reason, they have been proposed for use in laser interferometer gravitational-wave observatory (LIGO)-like gravity-wave detectors and in ring-laser gyroscopes. In this paper we analyze the quantum noise associated with anomalously dispersive cavity modes. The vacuum field energy associated with a particular cavity mode is proportional to the cavity-averaged group velocity of that mode. For anomalously dispersive cavities with group index values between 1 and 0, this means that the total vacuum field energy associated with a particular cavity mode must exceed ({h_bar}/2{pi}){omega}/2. For white-light cavities in particular, the group index approaches zero and the vacuum field energy of a particular spatial mode may be significantly enhanced. We predict enhanced spontaneous emission rates into anomalously dispersive cavity modes and broadened laser linewidths when the linewidth of intracavity emitters is broader than the cavity linewidth.

  10. A coupling model for amplified spontaneous emission in laser resonators

    NASA Astrophysics Data System (ADS)

    Su, Hua; Wang, Xiaojun; Shang, Jianli; Yu, Yi; Tang, Chun

    2015-10-01

    The competition between amplified spontaneous emission (ASE) and main laser in solid-state laser resonators is investigated both theoretically and experimentally. A coupled model using the spatial volume integral instead of the Monte Carlo type raytrace technique is proposed to depict ASE in the laser resonators. This model is able to evaluate all possible reflections at both the polishing surface and the diffusive side, to calculate ASE for an inhomogeneous gain distribution, and to include the spectral correction. An experiment is carefully designed to verify the theoretical model and to investigate the distinct physical properties caused by the coupling between ASE and the laser oscillations. The experimental data exhibit an excellent agreement with the theoretical predictions. According to that model, we confirm that ASE in thin-disk lasers can be characterized approximately by the product of the threshold gain of the resonator and the diameter of the disks, as laser modes are highly overlapped with the pumping beam. Theoretical evaluation shows that the scattering characteristic of the disk side impacts on ASE significantly. Furthermore, we point out that ASE decreases output laser power by affecting threshold pumping power, while slope efficiency is not changed by ASE. This observation provides us with a simple way to estimate the decrease of the optical efficiency by ASE.

  11. Efficient computation of spontaneous emission dynamics in arbitrary photonic structures

    NASA Astrophysics Data System (ADS)

    Teimourpour, M. H.; El-Ganainy, R.

    2015-12-01

    Defining a quantum mechanical wavefunction for photons is one of the remaining open problems in quantum physics. Thus quantum states of light are usually treated within the realm of second quantization. Consequently, spontaneous emission (SE) in arbitrary photonic media is often described by Fock space Hamiltonians. Here, we present a real space formulation of the SE process that can capture the physics of the problem accurately under different coupling conditions. Starting from first principles, we map the unitary evolution of a dressed two-level quantum emitter onto the problem of electromagnetic radiation from a self-interacting complex harmonic oscillator. Our formalism naturally leads to an efficient computational scheme of SE dynamics using finite difference time domain method without the need for calculating the photonic eigenmodes of the surrounding environment. In contrast to earlier investigations, our computational framework provides a unified numerical treatment for both weak and strong coupling regimes alike. We illustrate the versatility of our scheme by considering several different examples.

  12. Excitation dependent two-component spontaneous emission and ultrafast amplified spontaneous emission in dislocation-free InGaN nanowires

    SciTech Connect

    You, Guanjun; Zhang, Chunfeng; Xu, Jian; Guo, Wei; Bhattacharya, Pallab; Henderson, Ron

    2013-03-04

    Amplified spontaneous emission (ASE) at 456 nm from In{sub 0.2}Ga{sub 0.8}N nanowires grown on (001) silicon by catalyst-free molecular beam epitaxy was observed at room temperature under femtosecond excitation. The photoluminescence spectra below ASE threshold consist of two spontaneous emission bands centered at {approx}555 nm and {approx}480 nm, respectively, revealing the co-existence of deeply and shallowly localized exciton states in the nanowires. The ASE peak emerges from the 480 nm spontaneous emission band when the excitation density exceeds {approx}120 {mu}J/cm{sup 2}, indicating that optical gain arises from the radiative recombination of shallowly localized excitons in the nanowires. Time-resolved photoluminescence measurements revealed that the ASE process completes within 1.5 ps, suggesting a remarkably high stimulated emission recombination rate in one-dimensional InGaN nanowires.

  13. Automotive Emissions Control

    NASA Astrophysics Data System (ADS)

    Graham, George

    2002-03-01

    Serious efforts to control emissions from automobiles commenced more than thirty-five years ago, focusing initially on aspects of engine design and the combustion process. For the past quarter century, however, the major emphasis has been on treating the engine exhaust gas before it leaves the vehicle, in order to limit the release of toxic and other pollutants. The system that was eventually devised and is now used on most gasoline-burning automobiles combines sensing, electronic engine control, and catalysis to decrease the emission of certain pollutants by more than ninety percent. This presentation will describe how the system works and briefly touch upon some of the consequences of automotive emissions control.

  14. Modified spontaneous-emission rate in an inverted-opal structure with complete photonic bandgap

    NASA Astrophysics Data System (ADS)

    Hermann, Christian; Hess, Ortwin

    2002-12-01

    A finite three-dimensional photonic-crystal structure with a complete photonic bandgap is shown to drastically modify the spontaneous-emission rate of an embedded dipole. Calculations on the basis of the finite-difference time-domain method with perfectly matched layer boundary conditions demonstrate a strong position and polarization dependence of spontaneous emission within the unit cell. Strong enhancement effects are predicted at interfaces between the high-index and the low-index material. The inhibition of spontaneous emission within the bandgap is of the order of two magnitudes, even for relatively small crystallites.

  15. Automotive Emission Control.

    ERIC Educational Resources Information Center

    Lee, Billy D.; Ragazzi, Ronald

    This guide designed to assist teachers in improving instruction in the area of automotive emission control curriculum includes four areas. Each area consists of one or more units of instruction, with each instructional unit including some or all of the following basic components: Performance objectives, suggested activities for teacher and…

  16. Automotive Emission Control.

    ERIC Educational Resources Information Center

    Lee, Billy D.; And Others

    This publication contains instructional materials for both teachers and students for a course in automotive emission control. Instructional materials in this publication are written in terms of student performance using measurable objectives. The course includes 16 units. Each instructional unit includes some or all of the basic components of a…

  17. Fast and bright spontaneous emission of Er3+ ions in metallic nanocavity

    PubMed Central

    Song, Jung-Hwan; Kim, Jisu; Jang, Hoon; Yong Kim, In; Karnadi, Indra; Shin, Jonghwa; Shin, Jung H.; Lee, Yong-Hee

    2015-01-01

    By confining light in a small cavity, the spontaneous emission rate of an emitter can be controlled via the Purcell effect. However, while Purcell factors as large as ?10,000 have been predicted, actual reported values were in the range of about 1030 only, leaving a huge gap between theory and experiment. Here we report on enhanced 1.54-?m emission from Er3+ ions placed in a very small metallic cavity. Using a cavity designed to enhance the overall Purcell effect instead of a particular component, and by systematically investigating its photonic properties, we demonstrate an unambiguous Purcell factor that is as high as 170 at room temperature. We also observe >90 times increase in the far-field radiant flux, indicating that as much as 55% of electromagnetic energy that was initially supplied to Er3+ ions in the cavity escape safely into the free space in just one to two optical cycles. PMID:25940839

  18. Enhanced amplified spontaneous emission from colloidal quantum dots in all-dielectric monolithic microcavities

    NASA Astrophysics Data System (ADS)

    Goldberg, David; Menon, Vinod M.

    2013-02-01

    We report enhanced amplified spontaneous emission from CdSe/ZnS (core/shell) quantum dots embedded in an all-dielectric microcavity. The vertical cavity surface emitting structure was grown via plasma enhanced chemical vapor deposition and the quantum dots were sandwiched in the cavity layer via dip coating. The enhancement in emission is observed when the cavity mode is in resonance with the biexciton energy. The microcavity shows a factor of two improvement in the slope efficiency of amplified spontaneous emission along with significant modification in the directionality of the emission.

  19. A semi-analytical approach for evaluating effects of amplified spontaneous emission on characteristics of Q-switched lasers

    SciTech Connect

    Razzaghi, D; Hajiesmaeilbaigi, F; Ruzbehani, M

    2012-08-31

    Possible effects of amplified spontaneous emission on output pulse characteristics of a Q-switched laser are discussed within the framework of a semi-analytical approach. It is shown that output energy decreases almost exponentially with average path length of the spontaneously emitted photons which in turn depends on geometrical specification and active medium properties as well as on optical finishing of the surfaces (for solid-state lasers). Optimal coupling dependence on the average path length is also investigated and shown to increase with average path length increment. (control of laser radiation parameters)

  20. Excess spontaneous emission in non-Hermitian optical systems. I. Laser amplifiers

    SciTech Connect

    Siegman, A.E.

    1989-02-01

    Petermann first predicted in 1979 the existence of an excess-spontaneous-emission factor in gain-guided semiconductor lasers. We show that an excess spontaneous emission of this type, and also a correlation between the spontaneous emission into different cavity modes, will in fact be present in all open-sided laser resonators or optical lens guides. These properties arise from the non-self-adjoint or non-power-orthogonal nature of the optical resonator modes. The spontaneous-emission rate is only slightly enhanced in stable-resonator or index-guided structures, but can become very much larger than normal in gain-guided or geometrically unstable structures. Optical resonators or lens guides that have an excess noise emission necessarily also exhibit an ''excess initial-mode excitation factor'' for externally injected signals. As a result, the excess spontaneous emission can be balanced out and the usual quantum-noise limit recovered in laser amplifiers and in injection-seeded laser oscillators, but not in free-running laser oscillators.

  1. Manipulation of the spontaneous emission in mesoporous synthetic opals impregnated with fluorescent guests.

    PubMed

    Yamada, Yuri; Yamada, Hisashi; Nakamura, Tadashi; Yano, Kazuhisa

    2009-12-01

    The spontaneous emission of light from light-emitting materials adsorbed within the ordered pores of monodispersed mesoporous silica spheres (MMSS) has been investigated. By taking advantage of the ordered starburst pores of MMSS, we can provide a simple strategy for fabricating synthetic opals consisting of homogeneous individual building blocks in which fluorescent guests are uniformly and stably impregnated. In this study, tris(8-hydroxyquinolinato)aluminum(III) (Alq(3)) and Rhodamine B (Rh B) are selected as the fluorescent guests. The former has a wider emission band than the reflection spectrum of MMSS synthetic opals, whereas the emission band of the latter is considerably narrower than the reflection spectrum of the opals. The spontaneous emissions of these functionalized synthetic opals are clearly influenced by the stop band governed by the Bragg equation. In the case of the Alq(3)-MMSS conjugate, the shape of the Alq(3) emission spectrum varies in accordance with the shift in the stop band. The emission of the Rh B-MMSS conjugate is noticeably narrowed, and its intensity is enhanced when the excitation intensity is increased. These results are well explained by an inhibition of spontaneous emission caused by a reduction in the density of optical states within the stop band. The results of this study indicate that MMSS synthetic opals are promising for use in novel optical applications in which the spontaneous emission can be manipulated. PMID:19642624

  2. Spontaneous emission of electromagnetic radiation in turbulent plasmas

    SciTech Connect

    Ziebell, L. F.; Yoon, P. H.; Simões, F. J. R.; Pavan, J.; Gaelzer, R.; Instituto de Física e Matemática, UFPel, Pelotas, Rio Grande do Sul

    2014-01-15

    Known radiation emission mechanisms in plasmas include bremmstrahlung (or free-free emission), gyro- and synchrotron radiation, cyclotron maser, and plasma emission. For unmagnetized plasmas, only bremmstrahlung and plasma emissions are viable. Of these, bremmstrahlung becomes inoperative in the absence of collisions, and the plasma emission requires the presence of electron beam, followed by various scattering and conversion processes. The present Letter proposes a new type of radiation emission process for plasmas in a state of thermodynamic quasi-equilibrium between particles and enhanced Langmuir turbulence. The radiation emission mechanism proposed in the present Letter is not predicted by the linear theory of thermal plasmas, but it relies on nonlinear wave-particle resonance processes. The electromagnetic particle-in-cell numerical simulation supports the new mechanism.

  3. EMISSION CONTROL: CONTROL OF FINE PARTICULATE EMISSIONS

    EPA Science Inventory

    This paper reviews the results of fine particulate control technology tests by the Particulate Technology Branch (PATB) of EPA's IERL-RTP over the last 3 years. The review covers characterization of conventional control equipment, assessment of the collectability of dusts, and ne...

  4. Spontaneous emission lifetimes in the ground electronic states of HD/+/ and H2/+/a

    NASA Technical Reports Server (NTRS)

    Peek, J. M.; Hashemi-Attar, A.-R.; Beckel, C. L.

    1979-01-01

    Because of their simplicity, H2(+) and its isotopic species are of particular interest to molecular theorists and experimentalists. If these ions are formed in excited vibrational states under conditions of highly improbable electron-ion recombination or other reactions, spontaneous emission will occur. The present note calculates the (vibrational quantum number, J prime = 0) state lifetimes under spontaneous emission for all 22 excited vibrations of HD(+) and all 19 excited vibrations of H2(+) in their ground electron states. The lifetimes presented in Tables I and III justify the assumption that spontaneous radiative processes are unimportant under certain realizable conditions. When spontaneous radiation plays a role, however, minimum lifetime at intermediate vibrational quantum number could lead to unusual vibrational distribution functions.

  5. Protecting remote atomic entanglement against spontaneous emission by separated photonic pulses

    NASA Astrophysics Data System (ADS)

    Zong, Xiao-Lan; Du, Chao-Qun; Yang, Ming; Zhang, Gang; Yang, Qing; Cao, Zhuo-Liang

    2015-07-01

    We study the entanglement dynamics between two spatially separated atoms trapped in two separate optical cavities. Based on cavity-assisted interactions between the atoms and separated photonic pulses, we propose a scheme for the implemention of a controlled-phase-flip gate (CPF gate) between each of the atoms and the photonic pulse to protect the remote atomic quantum entanglement against the decaying caused by spontaneous emission. What we need to do is to shoot the horizontally polarized photons onto the cavity mirror successively, plus a train of Hadamard operations on the atoms, and no measurement is needed here. It is shown that the quantum entanglement of the two remote atoms can be protected effectively in this way. We also extend our scheme to the case of weak coupling and low Q cavity cases. The simplicity of the current scheme may warrant its experimental realization.

  6. Spontaneous emission by rotating objects: a scattering approach.

    PubMed

    Maghrebi, Mohammad F; Jaffe, Robert L; Kardar, Mehran

    2012-06-01

    We study the quantum electrodynamics vacuum in the presence of a body rotating along its axis of symmetry and show that the object spontaneously emits energy if it is lossy. The radiated power is expressed as a general trace formula solely in terms of the scattering matrix, making an explicit connection to the conjecture of Zel'dovich [JETP Lett. 14, 180 (1971)] on rotating objects. We further show that a rotating body drags along nearby objects while making them spin parallel to its own rotation axis. PMID:23003926

  7. Progress in emission control technologies

    SciTech Connect

    1994-12-31

    Partial contents of this book include: Ozone precursor emissions from alternatively fueled vehicles; Cycle resolved measurements of diesel particulate by optical techniques; A lubricant formulation for lower unburnt hydrocarbon emissions; Chassis test cycles for assessing emissions from heavy duty trucks; A non-intrusive method of measuring PCV blowby constituents; Some problems in the improvement of measurement of transient emissions; and Oxidation catalyst systems for emission control of LPG-powered forklift trucks.

  8. Bichromatic and trichromatic manipulation of spontaneous emission in a three-level Λ system

    NASA Astrophysics Data System (ADS)

    Hu, Xiang-ming; Xu, Qing; Li, Jing-yan; Li, Xiao-xia; Shi, Wen-xing; Zhang, Xiu

    2006-04-01

    Bichromatic and trichromatic manipulation of spontaneous emission in a three-level system in Λ configuration is studied on the basis of density matrix equation and quantum regression theorem. The spontaneous emission spectrum is numerically calculated by using harmonic expansion and matrix inversion. Two characteristic features are shown. Firstly, the central resonance peak, which is absent in the case of monochromatic excitation, is recovered for the bichromatic or trichromatic excitation. Secondly, selective elimination of the spectral lines is obtained by varying the amplitudes and phases of the trichromatic components. For the phase dependence, it is the sum of the relative phases of the two sideband components to the central component that plays a crucial role. The spontaneous emission spectrum is drastically modified once the sum phase is changed, but is kept unchanged regardless of the respective phases when the sum phase is fixed.

  9. Control of Emissions

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor); Chung, Landy (Inventor)

    2013-01-01

    Methods and apparatus utilizing chlorine dioxide and hydrogen peroxide are useful to reduce NOx emissions, as well as SOx and mercury (or other heavy metal) emissions, from combustion flue gas streams.

  10. Spontaneous emission from a two-level atom in a bisphere microcavity

    NASA Astrophysics Data System (ADS)

    Ochiai, Tetsuyuki; Inoue, Jun-Ichi; Sakoda, Kazuaki

    2006-12-01

    Dynamics of the spontaneous emission from a two-level atom embedded in a bisphere microcavity is analyzed theoretically. A bisphere supports a morphology-dependent resonance having such a high quality factor with local field enhancement that the strong coupling between the atom and the cavity can be realized. By taking full account of the photon degree of freedom, we derive theoretically the coupling constant between the atom and the cavity as well as the radiation damping constants, which are used in the conventional cavity QED approach. In addition, we show that the power spectrum of the spontaneous emission at a local observation point is strongly affected by the photon Green function.

  11. Spontaneous emission measurements from a low voltage pre-bunched electron beam

    SciTech Connect

    Dearden, G.; Mayhew, S.E.; Lucas, J.

    1995-12-31

    Recently we have carried out measurements on the spontaneous microwave (8.2 GHz) emission which results when a low-voltage (55kV) pre-punched electron beam is passed through a waveguide in a wiggler magnetic field. The variation of the spontaneous emission output power level with the average electron beam current and energy are reported and compared with the theory presented by Doria et al. The effect of the degree of bunching of the electron beam has also been observed and compared with theory.

  12. Spontaneous synchrotron emission from a plasma with an energetic runaway electron tail

    NASA Technical Reports Server (NTRS)

    Freund, H. P.; Dillenburg, D.; Wu, C. S.; Lee, L. C.

    1978-01-01

    The emissivity of spontaneous synchrotron radiation is computed for a plasma consisting of a background thermal plasma in addition to an energetic runaway electron component. The analysis is performed for both the ordinary and extraordinary modes, for frequencies in the vicinity of the electron plasma frequency and the higher harmonics of the electron gyrofrequency, and for the case when the electron plasma frequency is approximately the same as or smaller than the cyclotron frequency. The relativistic gyroresonance with the runaway electrons is found to result in a level of spontaneous emission which, for frequencies in the neighborhood of the electron plasma frequency, is significantly enhanced over the thermal radiation.

  13. Increased Spontaneous Otoacoustic Emissions in Mice with a Detached Tectorial Membrane.

    PubMed

    Cheatham, Mary Ann; Ahmad, Aisha; Zhou, Yingjie; Goodyear, Richard J; Dallos, Peter; Richardson, Guy P

    2016-04-01

    Mutations in genes encoding tectorial membrane (TM) proteins are a significant cause of human hereditary hearing loss (Hildebrand et al. 2011), and several mouse models have been developed to study the functional significance of this accessory structure in the mammalian cochlea. In this study, we use otoacoustic emissions (OAE), signals obtained from the ear canal that provide a measure of cochlear function, to characterize a mouse in which the TM is detached from the spiral limbus due to an absence of otoancorin (Otoa, Lukashkin et al. 2012). Our results demonstrate that spontaneous emissions (SOAE), sounds produced in the cochlea without stimulation, increase dramatically in mice with detached TMs even though their hearing sensitivity is reduced. This behavior is unusual because wild-type (WT) controls are rarely spontaneous emitters. SOAEs in mice lacking Otoa predominate around 7 kHz, which is much lower than in either WT animals when they generate SOAEs or in mutant mice in which the TM protein Ceacam16 is absent (Cheatham et al. 2014). Although both mutants lack Hensen's stripe, loss of this TM feature is only observed in regions coding frequencies greater than ~15 kHz in WT mice so its loss cannot explain the low-frequency, de novo SOAEs observed in mice lacking Otoa. The fact that ~80 % of mice lacking Otoa produce SOAEs even when they generate smaller distortion product OAEs suggests that the active process is still functioning in these mutants but the system(s) involved have become less stable due to alterations in TM structure. PMID:26691158

  14. Highly elevated emission of mercury vapor due to the spontaneous combustion of refuse in a landfill

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Sommar, Jonas; Li, Zhonggen; Feng, Xinbin; Lin, Che-Jen; Li, Guanghui

    2013-11-01

    Refuse disposal (e.g., landfilling and incineration) have been recognized as a significant anthropogenic source of mercury (Hg) emission globally. However, in-situ measurements of Hg emission from landfill or refuse dumping sites where fugitive spontaneous combustion occurs have not been reported. Gaseous elemental mercury (Hg0) concentration and emission flux were observed near spontaneous combustions of refuse at a landfill site in southwestern China. Ambient Hg0 concentrations above the refuse surface ranged from 42.7 ± 20.0 to 396.4 ± 114.2 ng m-3, up to 10 times enhancement due to the spontaneous burning. Using a box model with Hg0 data obtained from 2004 to 2013, we estimated that the Hg0 emission from refuse was amplified by 8-40 times due to spontaneous combustion. A micrometeorological flux measurement system based on relaxed eddy accumulation was configured downwind of the combustion sites to quantify the Hg0 emission. Extremely large turbulent deposition fluxes (up to -128.6 μg m-2 h-1, 20 min average) were detected during periods of high Hg0 concentration events over the measurement footprint. The effect of temperature, moisture and light on the air-surface exchange of Hg0 exchange was found to be masked by the overwhelming deposition of Hg0 from the enriched air from the refuse combustion plumes. This research reveals that mercury emission from the landfill refuse can be boosted by fugitive spontaneous combustion of refuse. The emission represents an anthropogenic source that has been overlooked in Hg inventory estimates.

  15. Electrically Controllable Spontaneous Magnetism in Nanoscale Mixed Phase Multiferroics

    SciTech Connect

    He, Q.; Chu, Y. H.; Heron, J. T.; Yang, S. Y.; Wang, C. H.; Kuo, C. Y.; Lin, H. J.; Yu, P.; Liang, C. W.; Zeches, R. J.; Chen, C. T.; Arenholz, E.; Scholl, A.; Ramesh, R.

    2010-08-02

    The emergence of enhanced spontaneous magnetic moments in self-assembled, epitaxial nanostructures of tetragonal (T-phase) and rhombohedral phases (R-phase) of the multiferroic BiFeO{sub 3} system is demonstrated. X-ray magnetic circular dichroism based photoemission electron microscopy (PEEM) was applied to investigate the local nature of this magnetism. We find that the spontaneous magnetization of the R-phase is significantly enhanced above the canted antiferromagnetic moment in the bulk phase, as a consequence of a piezomagnetic coupling to the adjacent T-phase and the epitaxial constraint. Reversible electric field control and manipulation of this magnetic moment at room temperature is shown using a combination of piezoresponse force microscopy and PEEM studies.

  16. Optical instabilities and spontaneous light emission in moving media

    NASA Astrophysics Data System (ADS)

    Silveirinha, Mario

    2015-03-01

    We show that when an uncharged plasmonic material is set in relative motion with respect to another uncharged polarizable body the system may be electromagnetically unstable. Particularly, when the relative velocity of the two bodies is enforced to remain constant the system may support natural oscillations that grow exponentially with time, even in presence of realistic material loss and dispersion. It is proven that a friction-type force acts on the moving bodies to oppose their relative motion. Hence, the optical instabilities result from the conversion of kinetic energy into electromagnetic energy. This new purely classical phenomenon is analogous to the Cherenkov and Smith-Purcell effects but for uncharged polarizable matter. We link the optical instabilities to a spontaneous parity-time symmetry breaking of the system, and demonstrate the possibility of optical amplification of a light pulse in the broken parity-time symmetry regime. This work is supported in part by Fundao para a Cincia e a Tecnologia Grant Number PTDC/EEI-TEL/2764/2012.

  17. Effect of surface-plasmon polaritons on spontaneous emission and intermolecular energy-transfer rates in multilayered geometries

    SciTech Connect

    Marocico, C. A.; Knoester, J.

    2011-11-15

    We use a Green's tensor method to investigate the spontaneous emission rate of a molecule and the energy-transfer rate between molecules placed in two types of layered geometries: a slab geometry and a planar waveguide. We focus especially on the role played by surface-plasmon polaritons in modifying the spontaneous emission and energy-transfer rates as compared to free space. In the presence of more than one interface, the surface-plasmon polariton modes split into several branches, and each branch can contribute significantly to modifying the electromagnetic properties of atoms and molecules. Enhancements of several orders of magnitude both in the spontaneous emission rate of a molecule and the energy-transfer rate between molecules are obtained and, by tuning the parameters of the geometry, one has the ability to control the range and magnitude of these enhancements. For the energy-transfer rate interference effects between contributions of different plasmon-polariton branches are observed as oscillations in the distance dependence of this rate.

  18. Comparative investigations of the spontaneous and stimulated emissions from nitrogen molecules in air with femtosecond laser excitation pulses

    NASA Astrophysics Data System (ADS)

    Li, Ziting; Chu, Wei; Zeng, Bin; Yao, Jinping; Li, Guihua; Xie, Hongqiang; Wang, Zhanshan; Cheng, Ya

    2016-03-01

    We report on experimental investigations on the spontaneous and stimulated emissions from excited nitrogen molecules generated in both linearly and circularly polarized intense laser fields. The spontaneous emission is measured from the side direction of the laser-induced filament whereas the stimulated emission generated by seed amplification is measured in the forward direction of the laser propagation. The comparison between the signal intensities of the spontaneous fluorescence emission and the seed-amplified stimulated emission provides an insight into the population inversion generated in nitrogen molecules with circularly polarized femtosecond laser pulses.

  19. Plasmonic engineering of spontaneous emission from silicon nanocrystals

    PubMed Central

    Goffard, Julie; Gérard, Davy; Miska, Patrice; Baudrion, Anne-Laure; Deturche, Régis; Plain, Jérôme

    2013-01-01

    Silicon nanocrystals offer huge advantages compared to other semi-conductor quantum dots as they are made from an abundant, non-toxic material and are compatible with silicon devices. Besides, among a wealth of extraordinary properties ranging from catalysis to nanomedicine, metal nanoparticles are known to increase the radiative emission rate of semiconductor quantum dots. Here, we use gold nanoparticles to accelerate the emission of silicon nanocrystals. The resulting integrated hybrid emitter is 5-fold brighter than bare silicon nanocrystals. We also propose an in-depth analysis highlighting the role of the different physical parameters in the photoluminescence enhancement phenomenon. This result has important implications for the practical use of silicon nanocrystals in optoelectronic devices, for instance for the design of efficient down-shifting devices that could be integrated within future silicon solar cells. PMID:24037020

  20. Nonlocal effects: relevance for the spontaneous emission rates of quantum emitters coupled to plasmonic structures

    NASA Astrophysics Data System (ADS)

    Filter, Robert; Bösel, Christoph; Toscano, Giuseppe; Lederer, Falk; Rockstuhl, Carsten

    2014-11-01

    The spontaneous emission rate of dipole emitters close to plasmonic dimers are theoretically studied within a nonlocal hydrodynamic model. A nonlocal model has to be used since quantum emitters in the immediate environment of a metallic nanoparticle probe its electronic structure. Compared to local calculations, the emission rate is significantly reduced. The influence is mostly pronounced if the emitter is located close to sharp edges. We suggest to use quantum emitters to test nonlocal effects in experimentally feasible configurations.

  1. Advanced Emissions Control Development Program

    SciTech Connect

    G. A. Farthing; G. T. Amrhein; G. A. Kudlac; D. A. Yurchison; D. K. McDonald; M. G. Milobowski

    2001-03-31

    The primary objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (HAPs, or air toxics) from coal-fired boilers. This objective is being met by identifying ways to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPs), fabric filters (fabric filters), and wet flue gas desulfurization (wet FGD) systems. Development work initially concentrated on the capture of trace metals, hydrogen chloride, and hydrogen fluoride. Recent work has focused almost exclusively on the control of mercury emissions.

  2. Low threshold amplified spontaneous emission and ambipolar charge transport in non-volatile liquid fluorene derivatives.

    PubMed

    Ribierre, Jean-Charles; Zhao, Li; Inoue, Munetomo; Schwartz, Pierre-Olivier; Kim, Ju-Hyung; Yoshida, Kou; Sandanayaka, Atula S D; Nakanotani, Hajime; Mager, Loic; Mry, Stphane; Adachi, Chihaya

    2016-02-11

    Highly fluorescent non-volatile fluidic fluorene derivatives functionalized with siloxane chains were synthesized and used in monolithic solvent-free liquid organic semiconductor distributed feedback lasers. The photoluminescence quantum yield values, the amplified spontaneous emission thresholds and the ambipolar charge carrier mobilities demonstrate that this class of materials is extremely promising for organic fluidic light-emitting and lasing devices. PMID:26734693

  3. Slow-light enhancement of spontaneous emission in active photonic crystal waveguides

    NASA Astrophysics Data System (ADS)

    Ek, Sara; Chen, Yaohui; Semenova, Elizaveta; Lunnemann Hansen, Per; Yvind, Kresten; Mrk, Jesper

    2012-03-01

    Photonic crystal defect waveguides with embedded active layers containing single or multiple quantum wells or quantum dots have been fabricated. Spontaneous emission spectra are enhanced close to the bandedge, consistently with the enhancement of gain by slow light effects. These are promising results for future compact devices for terabit/s communication, such as miniaturised semiconductor optical amplifiers and mode-locked lasers.

  4. Noise-color-induced quenching of fluctuations in a correlated spontaneous-emission laser model

    SciTech Connect

    Habiger, R.G.K.; Risken, H. ); James, M.; Moss, F. ); Schleich, W. Center for Advanced Studies and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 )

    1990-04-01

    We show via (1) an approximate, analytical technique, (2) a formally exact matrix continued-fraction analysis, and (3) an analog simulation of the classical Langevin equation of a correlated spontaneous-emission laser (CEL) that noise of nonzero correlation time leads to an enhancement of the characteristic CEL noise quenching.

  5. Spontaneous otoacoustic emissions, threshold microstructure, and psychophysical tuning over a wide frequency range in humansa

    PubMed Central

    Baiduc, Rachael R.; Lee, Jungmee; Dhar, Sumitrajit

    2014-01-01

    Hearing thresholds have been shown to exhibit periodic minima and maxima, a pattern known as threshold microstructure. Microstructure has previously been linked to spontaneous otoacoustic emissions (SOAEs) and normal cochlear function. However, SOAEs at high frequencies (>4 kHz) have been associated with hearing loss or cochlear pathology in some reports. Microstructure would not be expected near these high-frequency SOAEs. Psychophysical tuning curves (PTCs), the expression of frequency selectivity, may also be altered by SOAEs. Prior comparisons of tuning between ears with and without SOAEs demonstrated sharper tuning in ears with emissions. Here, threshold microstructure and PTCs were compared at SOAE frequencies ranging between 1.2 and 13.9 kHz using subjects without SOAEs as controls. Results indicate: (1) Threshold microstructure is observable in the vicinity of SOAEs of all frequencies; (2) PTCs are influenced by SOAEs, resulting in shifted tuning curve tips, multiple tips, or inversion. High frequency SOAEs show a greater effect on PTC morphology. The influence of most SOAEs at high frequencies on threshold microstructure and PTCs is consistent with those at lower frequencies, suggesting that high-frequency SOAEs reflect the same cochlear processes that lead to SOAEs at lower frequencies. PMID:24437770

  6. Fast and bright spontaneous emission of Er(3+) ions in metallic nanocavity.

    PubMed

    Song, Jung-Hwan; Kim, Jisu; Jang, Hoon; Yong Kim, In; Karnadi, Indra; Shin, Jonghwa; Shin, Jung H; Lee, Yong-Hee

    2015-01-01

    By confining light in a small cavity, the spontaneous emission rate of an emitter can be controlled via the Purcell effect. However, while Purcell factors as large as ∼10,000 have been predicted, actual reported values were in the range of about 10-30 only, leaving a huge gap between theory and experiment. Here we report on enhanced 1.54-μm emission from Er(3+) ions placed in a very small metallic cavity. Using a cavity designed to enhance the overall Purcell effect instead of a particular component, and by systematically investigating its photonic properties, we demonstrate an unambiguous Purcell factor that is as high as 170 at room temperature. We also observe >90 times increase in the far-field radiant flux, indicating that as much as 55% of electromagnetic energy that was initially supplied to Er(3+) ions in the cavity escape safely into the free space in just one to two optical cycles. PMID:25940839

  7. Decoherence of Quantum Tunneling Induced by Spontaneous Emission

    NASA Astrophysics Data System (ADS)

    Zheng, Li; Xiao, Zhi-Hong; Liu, Yu-Jie; Shi, Ying

    2015-07-01

    We study the decoherence dynamics of quantum tunneling of a two-level atom coupled into a single-mode electromagnetic field. Atomic internal and external degrees are entangled with the cavity field due to recoil during emission of a photon. We show that the quantum tunneling period depends on the distance between the two wells, and the tunneling process itself may or may not decohere depending on the distance between the two wells of the external potential compared to the wavelength corresponding to the internal transition.

  8. The interplay between spontaneous and controlled processing in creative cognition

    PubMed Central

    Mok, Leh Woon

    2014-01-01

    Neural studies of creativity have yielded relatively little consistent results. For example, in functional neuroanatomical studies, the prefrontal cortex (PFC) has often been implicated as a critical neural substrate. However, results in electrophysiological (EEG) studies have been inconsistent as to the role of the PFC. EEG results have more often implicated widespread alpha synchronization, particularly in posterior regions, in creative cognition. Recent fMRI evidence has indicated that the PFC may be activated as a part of and together with other components of a deliberate control brain network. Controlled processing is neurologically dissociated from, but may co-occur with, spontaneous cognition mediated by a subset of the default-mode network (e.g., the angular gyrus [BA 39] in the posterior parietal cortex, which has been increasingly implicated in creative cognition). When the demand for controlled processing is substantially increased, default-mode processing may be suppressed. There is now preliminary evidence to suggest an association between alpha synchronization and default-mode processing. Creative cognition likely emerges from an optimal balance between spontaneous processing and controlled processing. PMID:25221497

  9. Master equation for collective spontaneous emission with quantized atomic motion

    NASA Astrophysics Data System (ADS)

    Damanet, François; Braun, Daniel; Martin, John

    2016-02-01

    We derive a Markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion. Our equation provides a unifying picture of the consequences of recoil and indistinguishability of atoms beyond the Lamb-Dicke regime on both their dissipative and conservative dynamics, and applies equally well to distinguishable and indistinguishable atoms. We give general expressions for the decay rates and the dipole-dipole shifts for any motional states, and we find closed-form formulas for a number of relevant states (Gaussian states, Fock states, and thermal states). In particular, we show that dipole-dipole interactions and cooperative photon emission can be modulated through the external state of motion.

  10. Spontaneous ultraweak photon emission imaging of oxidative metabolic processes in human skin: effect of molecular oxygen and antioxidant defense system.

    PubMed

    Rastogi, Anshu; Pospsil, Pavel

    2011-09-01

    All living organisms emit spontaneous ultraweak photon emission as a result of cellular metabolic processes. In this study, the involvement of reactive oxygen species (ROS) formed as the byproduct of oxidative metabolic processes in spontaneous ultraweak photon emission was studied in human hand skin. The effect of molecular oxygen and ROS scavengers on spontaneous ultraweak photon emission from human skin was monitored using a highly sensitive photomultiplier tube and charged coupled device camera. When spontaneous ultraweak photon emission was measured under anaerobic conditions, the photon emission was decreased, whereas under hyperaerobic condition the enhancement in photon emission was observed. Spontaneous ultraweak photon emission measured after topical application of glutathione, ?-tocopherol, ascorbate, and coenzyme Q10 was observed to be decreased. These results reveal that ROS formed during the cellular metabolic processes in the epidermal cells play a significant role in the spontaneous ultraweak photon emission. It is proposed that spontaneous ultraweak photon emission can be used as a noninvasive tool for the temporal and spatial monitoring of the oxidative metabolic processes and intrinsic antioxidant system in human skin. PMID:21950919

  11. Spontaneous ultraweak photon emission imaging of oxidative metabolic processes in human skin: effect of molecular oxygen and antioxidant defense system

    NASA Astrophysics Data System (ADS)

    Rastogi, Anshu; Pospil, Pavel

    2011-09-01

    All living organisms emit spontaneous ultraweak photon emission as a result of cellular metabolic processes. In this study, the involvement of reactive oxygen species (ROS) formed as the byproduct of oxidative metabolic processes in spontaneous ultraweak photon emission was studied in human hand skin. The effect of molecular oxygen and ROS scavengers on spontaneous ultraweak photon emission from human skin was monitored using a highly sensitive photomultiplier tube and charged coupled device camera. When spontaneous ultraweak photon emission was measured under anaerobic conditions, the photon emission was decreased, whereas under hyperaerobic condition the enhancement in photon emission was observed. Spontaneous ultraweak photon emission measured after topical application of glutathione, ?-tocopherol, ascorbate, and coenzyme Q10 was observed to be decreased. These results reveal that ROS formed during the cellular metabolic processes in the epidermal cells play a significant role in the spontaneous ultraweak photon emission. It is proposed that spontaneous ultraweak photon emission can be used as a noninvasive tool for the temporal and spatial monitoring of the oxidative metabolic processes and intrinsic antioxidant system in human skin.

  12. Spontaneous emission in the presence of a realistically sized cylindrical waveguide

    NASA Astrophysics Data System (ADS)

    Dung, Ho Trung

    2016-02-01

    Various quantities characterizing the spontaneous emission process of a dipole emitter including the emission rate and the emission pattern can be expressed in terms of the Green tensor of the surrounding environment. By expanding the Green tensor around some analytically known background one as a Born series, and truncating it under appropriate conditions, complicated boundaries can be tackled with ease. However, when the emitter is embedded in the medium, even the calculation of the first-order term in the Born series is problematic because of the presence of a singularity. We show how to eliminate this singularity for a medium of arbitrary size and shape by expanding around the bulk medium rather than vacuum. In the highly symmetric configuration of an emitter located on the axis of a realistically sized cylinder, it is shown that the singularity can be removed by changing the integral variables and then the order of integration. Using both methods, we investigate the spontaneous emission rate of an initially excited two-level dipole emitter, embedded in a realistically sized cylinder, which can be a common optical fiber in the long-length limit and a disk in the short-length limit. The spatial distribution of the emitted light is calculated using the Born-expansion approach, and local-field corrections to the spontaneous emission rate are briefly discussed.

  13. Amplified spontaneous emission of glass forming DCM derivatives in PMMA films

    NASA Astrophysics Data System (ADS)

    Vembris, Aivars; Zarinsh, Elmars; Kokars, Valdis

    2014-05-01

    4-(dicyanomethylene)-2-methyl- 6-(p-dimethylaminostyryl)-4H-pyran (DCM) is well known red laser dye which can be used also in solid state organic lasers. The lowest threshold value of amplified spontaneous emission was achieved by doping 2wt% of DCM molecule in tris-(8-hydroxy quinoline) aluminium (Alq3) matrix. Further increase of dye concentration also increases threshold value. It is due to large intermolecular interaction which reduce photoluminescence quantum yield. Compounds with small intermolecular interaction and which exhibit similar amplified spontaneous properties as DCM could be useful for solid state organic lasers. In the work photoluminescence and amplified spontaneous emission properties of two DCM derivatives in poly (methyl methacrylate) (PMMA) matrix were investigated. Bulky trityloxyethyl groups are attached to the donor part of investigated molecules. These groups reduce intermolecular distance wherewith reduce photoluminescence quenching. More than one order of magnitude lower excitation threshold energy of the amplified spontaneous emission was achieved in doped polymer films with investigated compound in comparison to doped polymer with DCM. It means that the investigated compound is more perspective as a laser material compared to previously study.

  14. Emission control system

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor); Chung, J. Landy (Inventor)

    2009-01-01

    Methods and apparatus utilizing hydrogen peroxide are useful to reduce SOx and mercury (or other heavy metal) emissions from combustion flue gas streams. The methods and apparatus may further be modified to reduce NOx emissions. Continuous concentration of hydrogen peroxide to levels approaching or exceeding propellant-grade hydrogen peroxide facilitates increased system efficiency. In this manner, combustion flue gas streams can be treated for the removal of SOx and heavy metals, while isolating useful by-products streams of sulfuric acid as well as solids for the recovery of the heavy metals. Where removal of NOx emissions is included, nitric acid may also be isolated for use in fertilizer or other industrial applications.

  15. Nonresonant enhancement of spontaneous emission in metal-dielectric-metal plasmon waveguide structures

    SciTech Connect

    Jun, Y.C.

    2010-03-02

    We theoretically investigate the spontaneous emission process of an optical, dipolar emitter in metal-dielectric-metal slab and slot waveguide structures. We find that both structures exhibit strong emission enhancements at nonresonant conditions, due to the tight confinement of modes between two metallic plates. The large enhancement of surface plasmon-polariton excitation enables dipole emission to be preferentially coupled into plasmon waveguide modes. These structures find applications in creating nanoscale local light sources or in generating guided single plasmons in integrated optical circuits.

  16. Spontaneous emission with a cascaded driving field in the same transition channel

    NASA Astrophysics Data System (ADS)

    Liu, Ronggang; Liu, Tong

    2015-11-01

    We study the spontaneous emission spectrum of a driven four-level atom in both Markovian reservoir and non-Markovian reservoir, in which the two driving fields are applied to the same transition channel. It is very interesting that the increase of the Rabi frequency of the first driving field leads to the emission spectrum enhancement in Markovian reservoir, but the increase of the second one can suppress the emission spectrum significantly. The phenomenon originates from the dressed states variation induced by the first driving field. For non-Markovian reservoir case, the rich spectrum behavior is due to a strong coupling between driving fields and modified reservoir.

  17. Fabrication and characterization of plasmonic nanocone antennas for strong spontaneous emission enhancement

    NASA Astrophysics Data System (ADS)

    Hoffmann, Björn; Vassant, Simon; Chen, Xue-Wen; Götzinger, Stephan; Sandoghdar, Vahid; Christiansen, Silke

    2015-10-01

    Plasmonic antennas are attractive nanostructures for a large variety of studies ranging from fundamental aspects of light-matter interactions at the nanoscale to industry-relevant applications such as ultrasensitive sensing, enhanced absorption in solar cells or solar fuel generation. A particularly interesting feature of these antennas is that they can enhance the fluorescence properties of emitters. Theoretical calculations have shown that nanocone antennas provide ideal results, but a high degree of manufacturing precision and control is needed to reach optimal performance. In this study, we report on the fabrication of nanocones with base diameters and heights in the range of 100 nm with variable aspect ratios using focused ion beam milling of sputtered nano-crystalline gold layers. The controlled fabrication process allows us to obtain cones with tailored plasmon resonances. The measured plasmon spectra show very good agreement with finite-difference time-domain calculations. Theoretical investigations predict that these nanocones can enhance the spontaneous emission rate of a quantum emitter by several hundred times while keeping its quantum efficiency above 60%.

  18. Fabrication and characterization of plasmonic nanocone antennas for strong spontaneous emission enhancement.

    PubMed

    Hoffmann, Björn; Vassant, Simon; Chen, Xue-Wen; Götzinger, Stephan; Sandoghdar, Vahid; Christiansen, Silke

    2015-10-01

    Plasmonic antennas are attractive nanostructures for a large variety of studies ranging from fundamental aspects of light-matter interactions at the nanoscale to industry-relevant applications such as ultrasensitive sensing, enhanced absorption in solar cells or solar fuel generation. A particularly interesting feature of these antennas is that they can enhance the fluorescence properties of emitters. Theoretical calculations have shown that nanocone antennas provide ideal results, but a high degree of manufacturing precision and control is needed to reach optimal performance. In this study, we report on the fabrication of nanocones with base diameters and heights in the range of 100 nm with variable aspect ratios using focused ion beam milling of sputtered nano-crystalline gold layers. The controlled fabrication process allows us to obtain cones with tailored plasmon resonances. The measured plasmon spectra show very good agreement with finite-difference time-domain calculations. Theoretical investigations predict that these nanocones can enhance the spontaneous emission rate of a quantum emitter by several hundred times while keeping its quantum efficiency above 60%. PMID:26376922

  19. ADVANCED EMISSIONS CONTROL DEVELOPMENT PROGRAM

    SciTech Connect

    M.J. Holmes

    1998-07-01

    The objective of this project is to develop practical strategies and systems for the simultaneous control of SO{sub 2}, NO{sub x}, particulate matter, and air toxics emissions from coal-fired boilers in such a way as to keep coal economically and environmentally competitive as a utility boiler fuel. Of particular interest is the control of air toxics emissions through the cost-effective use of conventional flue gas clean-up equipment such as electrostatic precipitators (ESP's), fabric filters (baghouses), and SO{sub 2} removal systems such as wet scrubbers and various clean coal technologies. This objective will be achieved through extensive development testing in the state-of-the art, 10 MW{sub e} equivalent, Clean Environment Development Facility (CEDF). The project has extended the capabilities of the CEDF to facilitate air toxics emissions control development work on backend flue gas cleanup equipment. Specifically, an ESP, a baghouse, and a wet scrubber for SO{sub 2} (and air toxics) control were added--all designed to yield air toxics emissions data under controlled conditions, and with proven predictability to commercial systems. A schematic of the CEDF and the project test equipment is shown in Figure 1. The specific objectives of the project are to: (1) Measure and understand production and partitioning of air toxics species in coal-fired power plant systems; (2) Optimize the air toxics removal performance of conventional flue gas cleanup systems; (3) Quantify the impacts of coal cleaning on air toxics emissions; (4) Identify and/or develop advanced air toxics emissions control concepts; (5) Develop and validate air toxics emissions measurement and monitoring techniques; (6) Establish an air toxics data library to facilitate studies of the impacts of coal selection, coal cleaning, and emissions control strategies on the emissions of coal-fired power plants.

  20. ADVANCED EMISSIONS CONTROL DEVELOPMENT PROGRAM

    SciTech Connect

    M.J. Holmes

    1999-01-01

    The objective of this project is to develop practical strategies and systems for the simultaneous control of SO{sub 2}, NO{sub x}, particulate matter, and air toxics emissions from coal-fired boilers in such a way as to keep coal economically and environmentally competitive as a utility boiler fuel. Of particular interest is the control of air toxics emissions through the cost-effective use of conventional flue gas clean-up equipment such as electrostatic precipitators (ESP's), fabric filters (baghouses), and SO{sub 2} removal systems such as wet scrubbers and various clean coal technologies. This objective will be achieved through extensive development testing in the state-of-the art, 10 MW{sub e} equivalent, Clean Environment Development Facility (CEDF). The project has extended the capabilities of the CEDF to facilitate air toxics emissions control development work on backend flue gas cleanup equipment. Specifically, an ESP, a baghouse, and a wet scrubber for SO{sub 2} (and air toxics) control were added--all designed to yield air toxics emissions data under controlled conditions, and with proven predictability to commercial systems. A schematic of the CEDF and the project test equipment is shown in Figure 1. The specific objectives of the project are to: (1) Measure and understand production and partitioning of air toxics species in coal-fired power plant systems; (2) Optimize the air toxics removal performance of conventional flue gas cleanup systems; (3) Quantify the impacts of coal cleaning on air toxics emissions; (4) Identify and/or develop advanced air toxics emissions control concepts; (5) Develop and validate air toxics emissions measurement and monitoring techniques; (6) Establish an air toxics data library to facilitate studies of the impacts of coal selection, coal cleaning, and emissions control strategies on the emissions of coal-fired power plants.

  1. ADVANCED EMISSIONS CONTROL DEVELOPMENT PROGRAM

    SciTech Connect

    M.J. Holmes

    1998-10-01

    The objective of this project is to develop practical strategies and systems for the simultaneous control of SO{sub 2}, NO{sub x}, particulate matter, and air toxics emissions from coal-fired boilers in such a way as to keep coal economically and environmentally competitive as a utility boiler fuel. Of particular interest is the control of air toxics emissions through the cost-effective use of conventional flue gas clean-up equipment such as electrostatic precipitators (ESP's), fabric filters (baghouses), and SO{sub 2} removal systems such as wet scrubbers and various clean coal technologies. This objective will be achieved through extensive development testing in the state-of-the art, 10 MW{sub e} equivalent, Clean Environment Development Facility (CEDF). The project has extended the capabilities of the CEDF to facilitate air toxics emissions control development work on backend flue gas cleanup equipment. Specifically, an ESP, a baghouse, and a wet scrubber for SO{sub 2} (and air toxics) control were added--all designed to yield air toxics emissions data under controlled conditions, and with proven predictability to commercial systems. A schematic of the CEDF and the project test equipment is shown in Figure 1. The specific objectives of the project are to: (1) Measure and understand production and partitioning of air toxics species in coal-fired power plant systems; (2) Optimize the air toxics removal performance of conventional flue gas cleanup systems; (3) Quantify the impacts of coal cleaning on air toxics emissions; (4) Identify and/or develop advanced air toxics emissions control concepts; (5) Develop and validate air toxics emissions measurement and monitoring techniques; (6) Establish an air toxics data library to facilitate studies of the impacts of coal selection, coal cleaning, and emissions control strategies on the emissions of coal-fired power plants.

  2. Emission control system

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2008-01-01

    Methods and apparatus utilizing hydrogen peroxide are useful to reduce NOx, SOx and mercury (or other heavy metal) emissions from combustion flue gas streams. Continuous concentration of hydrogen peroxide to levels approaching or exceeding propellant-grade hydrogen peroxide facilitates increased system efficiency. In this manner, combustion flue gas streams can be treated for the removal of NOx, SOx and heavy metals, while isolating useful by-products streams of sulfuric acid and nitric acid as well as solids for the recovery of the heavy metals.

  3. Multicolor Amplified Spontaneous Emissions Based on Organic Polymorphs That Undergo Excited-State Intramolecular Proton Transfer.

    PubMed

    Cheng, Xiao; Zhang, Yufei; Han, Shenghua; Li, Feng; Zhang, Hongyu; Wang, Yue

    2016-03-24

    Two polymorphs emitting near-infrared (1 R form: α phase, λem =702 nm, Φf =0.41) and orange-red fluorescence (1 O form: β phase, λem =618 nm, Φf =0.05) were synthesized by finely controlling the crystallization conditions of compound 1, a structurally simple excited-state intramolecular proton transfer (ESIPT)-active molecule. Multicolor amplified spontaneous emissions (ASEs) were realized, for the first time, based on these polymorphs. Notably, the 1 O crystal underwent heating-induced phase transformation from the β phase to the α form in a single-crystal to single-crystal (SCSC) manner accompanied with an unprecedented ASE changing. The ASE behavior of polymorphs 1 R, 1 O as well as the ASE changing during SCSC was investigated. The feasibility of multicolor lasing based on the present organic polymorphs was confirmed, which may provide a new development strategy for organic laser science and technology. PMID:26917274

  4. Cavity-enhanced spontaneous emission rates for rhodamine 6-G in levitated microdroplets

    SciTech Connect

    Barnes, M.D.; Whitten, W.B.; Ramsey, J.M. ); Arnold, S. )

    1992-01-01

    Fluorescence decay kinetics of Rhodamine 6-G molecules in levitated glycerol microdroplets (4--20 microns in diameter) have been investigated to determine the effects of spherical cavity resonances on spontaneous emission rates. For droplet diameters greater than 10 microns, the fluorescence lifetime is essentially the same as in bulk glycerol. As the droplet diameter is decreased below 10 microns, bi-exponential decay behavior is observed with a slow component whose rate is similar to bulk glycerol, and a fast component whose rate is as much as a factor of 10 larger than the bulk decay rate. This fast component is attributed to cavity enhancement of the spontaneous emission rate and, within the weak coupling approximation, a value for the homogeneous linewidth at room temperature can be estimated from the fluorescence lifetime data.

  5. Cavity-enhanced spontaneous emission rates for rhodamine 6-G in levitated microdroplets

    SciTech Connect

    Barnes, M.D.; Whitten, W.B.; Ramsey, J.M.; Arnold, S.

    1992-11-01

    Fluorescence decay kinetics of Rhodamine 6-G molecules in levitated glycerol microdroplets (4--20 microns in diameter) have been investigated to determine the effects of spherical cavity resonances on spontaneous emission rates. For droplet diameters greater than 10 microns, the fluorescence lifetime is essentially the same as in bulk glycerol. As the droplet diameter is decreased below 10 microns, bi-exponential decay behavior is observed with a slow component whose rate is similar to bulk glycerol, and a fast component whose rate is as much as a factor of 10 larger than the bulk decay rate. This fast component is attributed to cavity enhancement of the spontaneous emission rate and, within the weak coupling approximation, a value for the homogeneous linewidth at room temperature can be estimated from the fluorescence lifetime data.

  6. Directional spontaneous emission and lateral Casimir-Polder force on an atom close to a nanofiber

    NASA Astrophysics Data System (ADS)

    Scheel, Stefan; Buhmann, Stefan Yoshi; Clausen, Christoph; Schneeweiss, Philipp

    2015-10-01

    We study the spontaneous emission of an excited atom close to an optical nanofiber and the resulting scattering forces. For a suitably chosen orientation of the atomic dipole, the spontaneous emission pattern becomes asymmetric and a resonant Casimir-Polder force parallel to the fiber axis arises. For a simple model case, we show that such a lateral force is due to the interaction of the circularly oscillating atomic dipole moment with its image inside the material. With the Casimir-Polder energy being constant in the lateral direction, the predicted lateral force does not derive from a potential in the usual way. Our results have implications for optical force measurements on a substrate as well as for laser cooling of atoms in nanophotonic traps.

  7. Precision localization of single atom via spontaneous emission in three dimensions

    NASA Astrophysics Data System (ADS)

    Wang, Zhiping; Yu, Benli

    2015-11-01

    We present a new scheme for high-efficiency three-dimensional (3D) atom localization in a three-level atomic system via spontaneous emission. Owing to the space-dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the spontaneous emission. It is found that, by properly varying the parameters of the system, the probability of finding the atom at a particular position can be almost 100 %. Our scheme opens a promising way to achieve high-precision and high-efficiency 3D atom localization, which provides some potential applications to spatially selective single-qubit phase gate, entangling gates, and quantum error correction for quantum information processing.

  8. Spontaneous and stimulated emission due to cooperative processes in cadmium telluride

    NASA Astrophysics Data System (ADS)

    Cingolani, A.; Ferrara, M.; Lugarà, M.; Avlijas, T.

    1984-08-01

    The spontaneous and the stimulated emission of both undoped and n-type CdTe crystals have been studied in a wide temperature range under dye laser excitation. Optical gain spectra have been also measured. The competition among the cooperative processes resulting in luminescence of CdTe is governed by the sample temperature and the doping level. When the exciton—electron collision is dominant, i.e. in n-type samples, the highest quantum efficiency is also achieved.

  9. GENERAL: Steady State Entanglement and Saturation Effects in Correlated Spontaneous Emission Lasers

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Hu, Xiang-Ming; Shi, Wen-Xing

    2009-08-01

    It has recently been shown that correlated spontaneous emission lasers (CEL) exhibit transient entanglement in the linear regime. Here we re-examine the quantum correlations in two-photon CEL and explore the saturation effects on continuous variable entanglement. It is shown that the steady state entanglement is obtainable in the weak or moderate saturation regime, while is washed out in the deep saturation regime.

  10. Enhanced Spontaneous Emission by Quantum Boxes in a Monolithic Optical Microcavity

    NASA Astrophysics Data System (ADS)

    Grard, J. M.; Sermage, B.; Gayral, B.; Legrand, B.; Costard, E.; Thierry-Mieg, V.

    1998-08-01

    Semiconductor quantum boxes (QB's) are well suited to cavity quantum electrodynamic experiments in the solid state because of their sharp emission. We study by time-resolved photoluminescence InAs QB's placed in the core of small-volume and high-finesse GaAs/AlAs pillar microresonators. A spontaneous emission rate enhancement by a factor of up to 5 is selectively observed for the QB's which are on resonance with one-cavity mode. We explain its magnitude by considering the Purcell figure of merit of the micropillars and the effect of the random spatial and spectral distributions of the QB's.

  11. Advanced Emissions Control Development Program: Mercury Control

    SciTech Connect

    Evans, A.P.; Redinger, K.W.; Holmes, M.J.

    1997-07-01

    McDermott Technology, Inc. (a subsidiary of Babcock & Wilcox) is conducting the Advanced Emissions Control Development Project (AECDP) which is aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (HAPS) from coal-fired electric utility plants. The need for such controls may arise as the US Environmental Protection Agency (EPA) proceeds with implementation of requirements set forth in the Clean Air Act Amendments (CAAA`s) of 1990. Promulgation of air toxics emissions regulations for electric utility plants could dramatically impact utilities burning coal, their industrial and residential customers, and the coal industry. AECDP project work will supply the information needed by utilities to respond to potential HAPs regulations in a timely, cost-effective, enviromnentally-sound manner which supports the continued use of the Nation`s abundant reserves of coal, such as those in the State of Ohio. The development work is being carried out using the 10 MW Clean Environment Development Facility wherein air toxics emissions control strategies can be developed under controlled conditions. The specific objectives of the project are to (1) measure and understand production and partitioning of air toxics species for a variety of coals, (2) optimize the air toxics removal performance of conventional flue gas cleanup systems, (3) develop advanced air toxics emissions control concepts, (4) develop and validate air toxics emissions measurement and monitoring techniques, and (5) establish a comprehensive, self-consistent air toxics data library. This project is supported by the Department of Energy, the Ohio Coal Development Office within the Ohio Department of Development and Babcock & Wilcox. A comprehensive assessment of HAP emissions from coal-fired electric utility boilers sponsored by the Department of Energy and the Electric Power Research Institute concluded that with the exception of selenium and mercury, the majority of trace elements are well controlled due to their association with the particulate phase of flue gas. Reflecting the current focus of the US EPA and state environmental agencies on mercury as a potential candidate for regulation, the project specifically targets the measurement and control of mercury species. This paper discusses the results of testing on the quantity and species distribution of mercury while firing Ohio high-sulfur coal to assess the mercury emissions control potential of conventional SO{sub 2} and particulate control systems. Results from recent AECDP tests are presented and two alternative mercury speciation methods are compared. The AECDP results clearly show that higher total mercury control efficiency can be achieved with a wet FGD scrubber than recently reported in the interim final US EPA report on HAP emissions from fossil-fired electric utility steam generating units.

  12. Spontaneous otoacoustic emissions in an active nonlinear cochlear model in the time domain

    NASA Astrophysics Data System (ADS)

    Fruth, Florian; Jlicher, Frank; Lindner, Benjamin

    2015-12-01

    A large fraction of human cochleas emits sounds even in the absence of external stimulation. These so-called spontaneous otoacoustic emissions (SOAEs) are a hallmark of the active nonlinear amplification process taking place in the cochlea. Here, we extend a previously proposed frequency domain model and put forward an active nonlinear one-dimensional model of the cochlea in the time domain describing human SOAEs [5]. In our model, oscillatory elements are close to an instability (Hopf bifurcation), they are subject to dynamical noise and coupled by hydrodynamic, elastic and dissipative interactions. Furthermore, oscillators are subject to a weak spatial irregularity in their activity (normally distributed and exponentially correlated in space) that gives rise to the individuality of each simulated cochlea. Our model captures main statistical features of the distribution of emission frequencies, the distribution of the numbers of emissions per cochlea, and the distribution of the distances between neighboring emissions as were previously measured in experiment [14].

  13. Advanced Emissions Control Development Program

    SciTech Connect

    A.P.Evans; K.E. Redinger; M.J. Holmes

    1998-04-01

    The objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. Ideally, the project aim is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPS), fabric filters (baghouse), and wet flue gas desulfurization. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate and hydrogen chloride. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on the evaluation of mercury and several other air toxics emissions. The AECDP is jointly funded by the United States Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (oCDO), and Babcock& Wilcox-a McDermott company (B&W).

  14. Using spontaneous photon emission to image lipid oxidation patterns in plant tissues.

    PubMed

    Birtic, Simona; Ksas, Brigitte; Genty, Bernard; Mueller, Martin J; Triantaphylids, Christian; Havaux, Michel

    2011-09-01

    Plants, like almost all living organisms, spontaneously emit photons of visible light. We used a highly sensitive, low-noise cooled charge coupled device camera to image spontaneous photon emission (autoluminescence) of plants. Oxidative stress and wounding induced a long-lasting enhancement of plant autoluminescence, the origin of which is investigated here. This long-lived phenomenon can be distinguished from the short-lived chlorophyll luminescence resulting from charge recombinations within the photosystems by pre-adapting the plant to darkness for about 2 h. Lipids in solvent were found to emit a persistent luminescence after oxidation in vitro, which exhibited the same time and temperature dependence as plant autoluminescence. Other biological molecules, such as DNA or proteins, either did not produce measurable light upon oxidation or they did produce a chemiluminescence that decayed rapidly, which excludes their significant contribution to the in vivo light emission signal. Selective manipulation of the lipid oxidation levels in Arabidopsis mutants affected in lipid hydroperoxide metabolism revealed a causal link between leaf autoluminescence and lipid oxidation. Addition of chlorophyll to oxidized lipids enhanced light emission. Both oxidized lipids and plants predominantly emit light at wavelengths higher than 600 nm; the emission spectrum of plant autoluminescence was shifted towards even higher wavelengths, a phenomenon ascribable to chlorophyll molecules acting as luminescence enhancers in vivo. Taken together, the presented results show that spontaneous photon emission imaged in plants mainly emanates from oxidized lipids. Imaging of this signal thus provides a simple and sensitive non-invasive method to selectively visualize and map patterns of lipid oxidation in plants. PMID:21595761

  15. Strong modification of quantum dot spontaneous emission via gap plasmon coupling in metal nanoslits

    SciTech Connect

    Jun, Y.C.

    2010-02-24

    A metal-dielectric-metal (MDM) waveguide with a nanoscale gap supports highly confined surface plasmon-polariton modes, termed gap plasmons. The spontaneous emission of an emitter placed in such a metal nanogap is expected to be strongly modified due to coupling to gap plasmons. We investigate the light emission properties of semiconductor quantum dots (QD) in a metal nanoslit, which is a truncated MDM waveguide. More specifically, we measure both the lifetime and the state of polarization of the out-coupled QD emission from a metal nanoslit. We observe clear lifetime and polarization changes of QD emission. As the slit width gets smaller, the QD exciton lifetime gradually decreases, and its emission becomes polarized normal to the slit, as expected for gap plasmon coupled light emission. We also find that the polarization of the collected QD emission is flipped (i.e., becomes parallel to a slit) when the excited emitters are located just outside the slit. We have conducted dipole emission calculations in metal nanoslits, and these explain the experimentally observed lifetime and polarization changes well. These findings may have novel applications in nanoscale optical sources, sensors, and active devices.

  16. Advanced Emission Control Development Program.

    SciTech Connect

    Evans, A.P.

    1997-12-31

    Babcock & Wilcox (B&W) is conducting a five-year project aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (commonly called air toxics) from coal-fired electric utility plants. The need for air toxic emissions controls may arise as the U. S. Environmental Protection Agency proceeds with implementation of Title III of the Clean Air Act Amendment (CAAA) of 1990. Data generated during the program will provide utilities with the technical and economic information necessary to reliably evaluate various air toxics emissions compliance options such as fuel switching, coal cleaning, and flue gas treatment. The development work is being carried out using B&W`s new Clean Environment Development Facility (CEDF) wherein air toxics emissions control strategies can be developed under controlled conditions, and with proven predictability to commercial systems. Tests conducted in the CEDF provide high quality, repeatable, comparable data over a wide range of coal properties, operating conditions, and emissions control systems. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate, and the inorganic species hydrogen chloride and hydrogen fluoride.

  17. Advanced Emissions Control Development Program

    SciTech Connect

    M. J. Holmes

    1998-12-03

    McDermott Technology, Inc. (MTI) is conducting a five-year project aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (commonly called air toxics) from coal-fired electric utility plants. The need for air toxic emissions controls may arise as the U. S. Environmental Protection Agency proceeds with implementation of Title III of the Clean Air Act Amendment (CAAA) of 1990. Data generated during the program will provide utilities with the technical and economic information necessary to reliably evaluate various air toxics emissions compliance options such as fuel switching, coal cleaning, and flue gas treatment. The development work is being carried out using the Clean Environment Development Facility (CEDF) wherein air toxics emissions control strategies can be developed under controlled conditions, and with proven predictability to commercial systems. Tests conducted in the CEDF provide high quality, repeatable, comparable data over a wide range of coal properties, operating conditions, and emissions control systems. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate, and hydrogen chloride and hydrogen fluoride.

  18. Advanced Emissions Control Development Program

    SciTech Connect

    A. P. Evans

    1998-12-03

    McDermott Technology, Inc. (MTI) is conducting a five-year project aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (commonly called air toxics) from coal-fired electric utility plants. The need for air toxic emissions controls may arise as the U. S. Environmental Protection Agency proceeds with implementation of Title III of the Clean Air Act Amendment (CAAA) of 1990. Data generated during the program will provide utilities with the technical and economic information necessary to reliably evaluate various air toxics emissions compliance options such as fuel switching, coal cleaning, and flue gas treatment. The development work is being carried out using the Clean Environment Development Facility (CEDF) wherein air toxics emissions control strategies can be developed under controlled conditions, and with proven predictability to commercial systems. Tests conducted in the CEDF provide high quality, repeatable, comparable data over a wide range of coal properties, operating conditions, and emissions control systems. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate, and the inorganic species, hydrogen chloride and hydrogen fluoride.

  19. Advanced Emissions Control Development Program

    SciTech Connect

    A. P. Evans

    1998-12-03

    Babcock & Wilcox (B&W) is conducting a five-year project aimed at the development of practical, cost-effective strategies for reducing the emissions of hazardous air pollutants (commonly called air toxics) from coal-fired electric utility plants. The need for air toxic emissions controls may arise as the U. S. Environmental Protection Agency proceeds with implementation of Title III of the Clean Air Act Amendment (CAAA) of 1990. Data generated during the program will provide utilities with the technical and economic information necessary to reliably evaluate various air toxics emissions compliance options such as fuel switching, coal cleaning, and flue gas treatment. The development work is being carried out using B&W�s new Clean Environment Development Facility (CEDF) wherein air toxics emissions control strategies can be developed under controlled conditions, and with proven predictability to commercial systems. Tests conducted in the CEDF provide high quality, repeatable, comparable data over a wide range of coal properties, operating conditions, and emissions control systems. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate, and the inorganic species hydrogen chloride and hydrogen fluoride.

  20. Spontaneous emission of electric and magnetic dipoles in the vicinity of thin and thick metal.

    PubMed

    Hussain, R; Keene, D; Noginova, N; Durach, M

    2014-04-01

    Strong modification of spontaneous emission of Eu(3+) ions placed in close vicinity to thin and thick gold and silver films was clearly demonstrated in a microscope setup separately for electric and magnetic dipole transitions. We have shown that the magnetic transition was very sensitive to the thickness of the gold substrate and behaved distinctly different from the electric transition. The observations were described theoretically based on the dyadic Green's function approach for layered media and explained through modified image models for the near and far-field emissions. We established that there exists a "near-field event horizon", which demarcates the distance from the metal at which the dipole emission is taken up exclusively in the near field. PMID:24718150

  1. Worldwide emission control: Automotive catalysts

    SciTech Connect

    Not Available

    1985-01-01

    This book presents the papers given at a conference on catalytic converters for internal combustion engines. Topics considered at the conference included catalytic automotive exhaust purification, exhaust emission control in Western Europe, three-way catalysts, the durability of automotive catalysts for European applications, and the high temperature aging cycle for European catalyst applications.

  2. Molecular hot electroluminescence due to strongly enhanced spontaneous emission rates in a plasmonic nanocavity.

    PubMed

    Chen, Gong; Li, Xiao-Guang; Zhang, Zhen-Yu; Dong, Zhen-Chao

    2015-02-14

    We have recently demonstrated anomalous relaxationless hot electroluminescence from molecules in the tunnel junction of a scanning tunneling microscope [Dong et al., Nat. Photonics, 2010, 4, 50]. In the present paper, based on physically realistic parameters, we aim to unravel the underlying physical mechanism using a multiscale modeling approach that combines classical generalized Mie theory with the quantum master equation. We find that the nanocavity-plasmon-tuned spontaneous emission rate plays a crucial role in shaping the spectral profile. In particular, on resonance, the radiative decay rate can be enhanced by three-to-five orders of magnitude, which enables the radiative process to occur on the lifetime scale of picoseconds and become competitive to the vibrational relaxation. Such a large Purcell effect opens up new emission channels to generate the hot luminescence that arises directly from higher vibronic levels of the molecular excited state. We also stress that the critical role of resonant plasmonic nanocavities in tunneling electron induced molecular luminescence is to enhance the spontaneous radiative decay through plasmon enhanced vacuum fluctuations rather than to generate an efficient plasmon stimulated emission process. This improved understanding has been partly overlooked in previous studies but is believed to be very important for further developments of molecular plasmonics and optoelectronics. PMID:25565003

  3. Bremsstrahlung emission of high energy accompanying spontaneous fission of {sup 252}Cf

    SciTech Connect

    Maydanyuk, S. P.; Olkhovsky, V. S.; Mandaglio, G.; Manganaro, M.; Fazio, G.; Giardina, G.

    2010-07-15

    The study of the bremsstrahlung photon emission accompanying fragments produced in the spontaneous fission of heavy nuclei by a fully quantum approach is presented for the first time. This kind of problem requires the knowledge of wave functions of the fissioning system leading to a wide distribution of couples of fragments that are the products of fission. With the aim of obtaining these wave functions, the interaction potential between the emitted fragment and residual nucleus is calculated by a standard approach. A new procedure was performed that allows an increase in the accuracy of calculations of radial integrals in the far asymptotic region and the achievement of the convenient convergence in calculations of the spectra. The total probability of the emitted photons in the spontaneous fission of {sup 252}Cf was calculated in such a way. We obtained good agreement between theory and experimental data up to 38 MeV for the bremsstrahlung spectrum of photons while the calculation of the total probability of photon emission accompanying fragments was performed up to an energy of 60 MeV. The analysis of contributions in the bremsstrahlung spectrum accompanying the emission of light, medium, and heavy fragments in the fission of {sup 252}Cf is presented.

  4. An Active Oscillator Model Describes the Statistics of Spontaneous Otoacoustic Emissions

    PubMed Central

    Fruth, Florian; Jlicher, Frank; Lindner, Benjamin

    2014-01-01

    Even in the absence of external stimulation, the cochleas of most humans emit very faint sounds below the threshold of hearing, sounds that are known as spontaneous otoacoustic emissions. They are a signature of the active amplification mechanism in the cochlea. Emissions occur at frequencies that are unique for an individual and change little over time. The statistics of a population of ears exhibit characteristic features such as a preferred relative frequency distance between emissions (interemission intervals). We propose a simplified cochlea model comprising an array of active nonlinear oscillators coupled both hydrodynamically and viscoelastically. The oscillators are subject to a weak spatial disorder that lends individuality to the simulated cochlea. Our model captures basic statistical features of the emissions: distributions of 1), emission frequencies; 2), number of emissions per ear; and 3), interemission intervals. In addition, the model reproduces systematic changes of the interemission intervals with frequency. We show that the mechanism for the preferred interemission interval in our model is the occurrence of synchronized clusters of oscillators. PMID:25140416

  5. An erbium-doped 1-D fiber-Bragg grating and its effect upon erbium (3+) radiative spontaneous emission

    NASA Astrophysics Data System (ADS)

    Boggs, Bryan S.

    Spontaneous atomic emission is not a process of the isolated atom but rather a cooperative effect of the atom and the vacuum field. It is now well established that spontaneous radiative decay rates can be enhanced or suppressed through the effect of cavities comprising various types of discrete, reflective-mirror type, boundaries. The cavity effect is generally understood in terms of a cavity-induced modification of the vacuum spectral energy density. Recently, interest has grown in the possibility that systems characterized by distributed periodic boundary conditions, such as a spatially varying index of refraction, might be effective in controlling radiative atomic processes. A semi-classical theory is given that enables an estimate of the size of the lifetime modification of a two-level radiator contained within a three-dimensionally incomplete photonic bandgap structure called a fiber-Bragg grating. Following this is an exploration of a specific system and its effect upon radiative spontaneous emission. It is found through fluorescence line narrowing and frequency hole burning measurements that the observation of lifetime modification of the specific system is complicated due to intra and inter Stark energy migration. A lifetime modification measurement then shows that no change in lifetime is observed beyond the error bars on the measurement results. The tuning and coherence properties of a short-external-cavity diode laser that may be useful for future time-dependent spectroscopic measurements are examined using a fiber-based, self-heterodyne technique. Coherence properties during active frequency scans are characterized through analysis of time-dependent heterodyne beat signals at the output of a fiber interferometer.

  6. Trace element emissions from spontaneous combustion of gob piles in coal mines, Shanxi, China

    USGS Publications Warehouse

    Zhao, Y.; Zhang, Jiahua; Chou, C.-L.; Li, Y.; Wang, Z.; Ge, Y.; Zheng, C.

    2008-01-01

    The emissions of potentially hazardous trace elements from spontaneous combustion of gob piles from coal mining in Shanxi Province, China, have been studied. More than ninety samples of solid waste from gob piles in Shanxi were collected and the contents of twenty potentially hazardous trace elements (Be, F, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, Hg, Tl, Pb, Th, and U) in these samples were determined. Trace element contents in solid waste samples showed wide ranges. As compared with the upper continental crust, the solid waste samples are significantly enriched in Se (20x) and Tl (12x) and are moderately enriched in F, As, Mo, Sn, Sb, Hg, Th, and U (2-5x). The solid waste samples are depleted in V, Cr, Mn, Co, Ni, Cu, and Zn. The solid waste samples are enriched in F, V, Mn, Cr, Co, Ni, Cu, Zn, Sb, Th, and U as compared with the Shanxi coals. Most trace elements are higher in the clinker than in the unburnt solid waste except F, Sn, and Hg. Trace element abundances are related to the ash content and composition of the samples. The content of F is negatively correlated with the ash content, while Pb is positively correlated with the ash. The concentrations of As, Mn, Zn, and Cd are highly positively correlated with Fe2O3 in the solid waste. The As content increases with increasing sulfur content in the solid waste. The trace element emissions are calculated for mass balance. The emission factors of trace elements during the spontaneous combustion of the gobs are determined and the trace element concentrations in the flue gas from the spontaneous combustion of solid waste are calculated. More than a half of F, Se, Hg and Pb are released to the atmosphere during spontaneous combustion. Some trace element concentrations in flue gas are higher than the national emission standards. Thus, gob piles from coal mining pose a serious environmental problem. ?? 2007 Elsevier B.V. All rights reserved.

  7. Study of the amplified spontaneous emission in a dye-doped biopolymer-based material

    NASA Astrophysics Data System (ADS)

    Mysliwiec, J.; Sznitko, L.; Miniewicz, A.; Kajzar, F.; Sahraoui, B.

    2009-04-01

    In this paper we investigate the amplified spontaneous emission (ASE) phenomenon in the system based on a dye dissolved in a modified deoxyribonucleic acid (DNA). The system consisted of a biopolymeric matrix made of DNA blended with cationic surfactant molecule cetyltrimethyl-ammonium chloride (CTMA) and doped with a well-known rhodamine (Rh 6G) laser dye. Thin films of the DNA-CTMA : Rh6G were excited at ? = 532 nm wavelength with 8 ns laser pulses. We report on ASE intensity as a function of the laser power, dependence of polarization state of the excitation beam, ASE gain and temporal stability of the signal for the investigated system.

  8. Modeling of an optically side-pumped alkali vapor amplifier with consideration of amplified spontaneous emission.

    PubMed

    Yang, Zining; Wang, Hongyan; Lu, Qisheng; Hua, Weihong; Xu, Xiaojun

    2011-11-01

    Diode pumped alkali vapor amplifier (DPAA) is a potential candidate in high power laser field. In this paper, we set up a model for the diode double-side-pumped alkali vapor amplifier. For the three-dimensional volumetric gain medium, both the longitudinal and transverse amplified spontaneous emission (ASE) effects are considered and coupled into the rate equations. An iterative numerical approach is proposed to solve the model. Some important influencing factors are simulated and discussed. The results show that in the case of saturated amplification, the ASE effect can be well suppressed rather than a limitation in power scaling of a DPAA. PMID:22109192

  9. Modified spontaneous emission of organic molecules in-filled in inverse opals.

    PubMed

    Deng, Lier; Wang, Yongsheng; He, Dawei

    2011-11-01

    Inverse opals were prepared by replication of colloidal crystal templates made from silica spheres 298 nm in diameter. The air between the silica spheres was filled with the mixture of the monomer poly(methyl methacrylate) (PMMA) and the organic molecule Alq3 that can be subsequently polymerized. After removing the silica sphere templates, the photonic bandgap effect on the spontaneous emission of Alq3 were investigated. The dip in the fluorescence spectrum was interpreted in terms of redistribution of the photon density of states in the photonic crystal. PMID:22413286

  10. Broadband filters for abatement of spontaneous emission in circuit quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Bronn, Nicholas T.; Liu, Yanbing; Hertzberg, Jared B.; Crcoles, Antonio D.; Houck, Andrew A.; Gambetta, Jay M.; Chow, Jerry M.

    2015-10-01

    The ability to perform fast, high-fidelity readout of quantum bits (qubits) is essential to the goal of building a quantum computer. However, coupling a fast measurement channel to a superconducting qubit typically also speeds up its relaxation via spontaneous emission. Here, we use impedance engineering to design a filter by which photons may easily leave the resonator at the cavity frequency but not at the qubit frequency. We implement this broadband filter in both an on-chip and off-chip configuration.

  11. Spontaneous Emission Spectrum of a ?-Typed Atom in a Coherent Photonic Reservoir

    NASA Astrophysics Data System (ADS)

    Huang, Xian-Shan; Liu, Hai-Lian

    2011-12-01

    The spontaneous emission of a three-level A-typed atom embedded in anisotropic photonic crystals with two coherent bands is investigated. The relative position of the atom is described by a position-dependent parameter ?(r0), in regard as the coherence of the two bands. The spectrum of the transition in free space vacuum is discussed. The spectral center can be manipulated by the coherent parameter ?(r0), and the spectral intensity can be adjusted via the atomic transition in the coherent photonic reservoir.

  12. Amplified spontaneous emission of Rhodamine 6G embedded in pure deoxyribonucleic acid

    NASA Astrophysics Data System (ADS)

    Rau, Ileana; Szukalski, Adam; Sznitko, Lech; Miniewicz, Andrzej; Bartkiewicz, Stanislaw; Kajzar, Francois; Sahraoui, Bouchta; Mysliwiec, Jaroslaw

    2012-10-01

    Deoxyribonucleic acid (DNA) is commonly viewed as a genetic information carrier. However, now it is recognized as a nanomaterial, rather than as a biological material, in the research field of nanotechnology. Here, we show that using pure DNA, doped with rhodamine 6G, we are able to observe amplified spontaneous emission (ASE) phenomenon. Moderate ASE threshold, photodegradation, and reasonable gain coefficient observed in this natural host gives some perspectives for practical applications of this system in biophotonics. Obtained results open the way and will be leading to construction of truly bio-lasers using nature made luminophores, such as anthocyanins.

  13. Light-charged-particle emission in the spontaneous fission of /sup 250/Cf, /sup 256/Fm, and /sup 257/Fm

    SciTech Connect

    Wild, J.F.; Baisden, P.A.; Dougan, R.J.; Hulet, E.K.; Lougheed, R.W.; Landrum, J.H.

    1985-08-01

    We have measured the energy spectra for the emission of long-range ..cap alpha.. particles from the spontaneous fission of /sup 250/Cf, /sup 256/Fm, and /sup 257/Fm, and for tritons and protons from the spontaneous fission of /sup 250/Cf and /sup 256/Fm. We have determined ..cap alpha.., triton, and proton emission probabilities and estimated total light-particle emission probabilities for these nuclides. We compare these and known emission probabilities for five other spontaneously fissioning nuclides with the deformation energy available at scission and show that there is a possible correlation that is consistent with a one-body dissipation mechanism for transferring release energy to particle clusters.

  14. Amplified spontaneous emission and lasing from lanthanide-doped up-conversion nanocrystals.

    PubMed

    Zhu, Hai; Chen, Xian; Jin, Li Min; Wang, Qi Jie; Wang, Feng; Yu, Siu Fung

    2013-12-23

    Lanthanide-doped nanocrystals (NCs), which found applications in bioimaging and labeling, have recently demonstrated significant improvement in up-conversion efficiency. Here, we report the first up-conversion multicolor microcavity lasers by using NaYF4:Yb/Er@NaYF4 core-shell NCs as the gain medium. It is shown that the optical gain of the NCs, which arises from the 2- and 3-photon up-conversion processes, can be maximized via sequential pulses pumping. Amplified spontaneous emission is observed from a Fabry-Perot cavity containing the NCs dispersed in cyclohexane solution. By coating a drop of silica resin containing the NCs onto an optical fiber, a microcavity with a bottle-like geometry is fabricated. It is demonstrated that the microcavity supports lasing emission through the formation of whispering gallery modes. PMID:24266853

  15. On the spontaneous emission of electromagnetic radiation in the CSL model

    SciTech Connect

    Donadi, Sandro; Istituto Nazionale di Fisica Nucleare, Trieste Section, Via Valerio 2, 34127 Trieste ; Deckert, Dirk-Andr; Bassi, Angelo; Istituto Nazionale di Fisica Nucleare, Trieste Section, Via Valerio 2, 34127 Trieste

    2014-01-15

    Spontaneous photon emission in the Continuous Spontaneous Localization (CSL) model is studied one more time. In the CSL model each particle interacts with a noise field that induces the collapse of its wave function. As a consequence of this interaction, when the particle is electrically charged, it radiates. As discussed in Adler (2013) the formula for the emission rate, to first perturbative order, contains two terms: one is proportional to the Fourier component of the noise field at the same frequency as that of the emitted photon and one is proportional to the zero Fourier component of the noise field. As discussed in previous works, this second term seems unphysical. In Adler (2013) it was shown that the unphysical term disappears when the noise is confined to a bounded region and the final particles state is a wave packet. Here we investigate the origin of this unphysical term and why it vanishes according to the previous prescription. We will see that perturbation theory is formally not valid in the large time limit since the effect of the noise accumulates continuously in time. Therefore either one performs an exact calculation (or at least in some way includes higher order terms) as we do here, or one finds a way to make a perturbative calculation meaningful, e.g., by confining the system as in Adler (2013). -- Highlights: We compute the electromagnetic radiation emission in collapse models. Under only the dipole approximation, the equations of motion are solved exactly. The electromagnetic interaction must be treated exactly. In order to obtain the correct emission rate the particle must be bounded.

  16. Madey's theorems for free-electron devices, spontaneous emission, and applications

    NASA Astrophysics Data System (ADS)

    Becker, W.; McIver, J. K.

    1988-12-01

    Two theorems due to Madey occupy a central position in free-electron laser physics: one relates the gain to the derivative of the spontaneous emission line shape and the other one relates it to the derivative of the electron energy spread in stimulated emission. We use quantum mechanical perturbation thoery of first order in the radiation field to give a general derivation of the theorems based on (a) the hermiticity of the electronfield interaction, (b) the applicability of lowest order perturbation theory, and (c) the assumption that the emitted photon have a sufficiently low energy. Assumption (b) restricts the validity of the theorems to the small-signal weak-field regime, (c) to the small recoil regime where the gain is classical. We use scalar quantum electrodynamics in the Furry picture in order to keep effects which are nonlinear in the undulator field, e.g. higher harmonic emission. We consider a fairly general one-dimensional (i.e. not having transverse variations) monochromatic undulator field (magnetic or optical undulator, linear or circular polarization, possible presence of a diffractive medium). An appendix considers nonmonochromatic fields. We derive explicit results for the linearly polarized and the helical undulator allowing for an arbitrary orientation of the undulator axis, the electron beam and the emitted radiation with respect to each other. In particular, we discuss the case of Gaussian modes where the applicability of the first theorem has been questioned. It turns out that the theorem is applicable provided that spontaneous emission into the Gaussian mode in question is considered (more generally, into whatever mode is of interest for the gain).

  17. Brillouin optical correlation domain analysis with 4 millimeter resolution based on amplified spontaneous emission.

    PubMed

    Cohen, Raphael; London, Yosef; Antman, Yair; Zadok, Avi

    2014-05-19

    A new technique for Brillouin scattering-based, distributed fiber-optic measurements of temperature and strain is proposed, analyzed, simulated, and demonstrated. Broadband Brillouin pump and signal waves are drawn from the filtered amplified spontaneous emission of an erbium-doped fiber amplifier, providing high spatial resolution. The reconstruction of the position-dependent Brillouin gain spectra along 5 cm of a silica single-mode fiber under test, with a spatial resolution of 4 mm, is experimentally demonstrated using a 25 GHz-wide amplified spontaneous emission source. A 4 mm-long localized hot spot is identified by the measurements. The uncertainty in the reconstruction of the local Brillouin frequency shift is 1.5 MHz. The single correlation peak between the pump and signal is scanned along a fiber under test using a mechanical variable delay line. The analysis of the expected spatial resolution and the measurement signal-to-noise ratio is provided. The measurement principle is supported by numerical simulations of the stimulated acoustic field as a function of position and time. Unlike most other Brillouin optical correlation domain analysis configurations, the proposed scheme is not restricted by the bandwidth of available electro-optic modulators, microwave synthesizers, or pattern generators. Resolution is scalable to less than one millimeter in highly nonlinear media. PMID:24921326

  18. On the spontaneous emission of electromagnetic radiation in the CSL model

    NASA Astrophysics Data System (ADS)

    Donadi, Sandro; Deckert, Dirk-André; Bassi, Angelo

    2014-01-01

    Spontaneous photon emission in the Continuous Spontaneous Localization (CSL) model is studied one more time. In the CSL model each particle interacts with a noise field that induces the collapse of its wave function. As a consequence of this interaction, when the particle is electrically charged, it radiates. As discussed in Adler (2013) the formula for the emission rate, to first perturbative order, contains two terms: one is proportional to the Fourier component of the noise field at the same frequency as that of the emitted photon and one is proportional to the zero Fourier component of the noise field. As discussed in previous works, this second term seems unphysical. In Adler (2013) it was shown that the unphysical term disappears when the noise is confined to a bounded region and the final particle's state is a wave packet. Here we investigate the origin of this unphysical term and why it vanishes according to the previous prescription. We will see that perturbation theory is formally not valid in the large time limit since the effect of the noise accumulates continuously in time. Therefore either one performs an exact calculation (or at least in some way includes higher order terms) as we do here, or one finds a way to make a perturbative calculation meaningful, e.g., by confining the system as in Adler (2013).

  19. Parasitic Oscillations And Amplified Spontaneous Emission In Face-Pumped Total Internal Reflection Lasers

    NASA Astrophysics Data System (ADS)

    Brown, D. C.; Benfey, D. P.; Gehm, W. J.; Holmes, D. H.; Lee, K. K.

    1987-04-01

    Parasitic oscillations and amplified spontaneous emission (ASE) can often strongly influence the operation and efficiency of laser devices, as has been shown previously for disk and active-mirror amplifiers. Here we report the first comprehensive investigation of those phenomena in total internal reflection (TIR) face-pumped lasers. The results to be presented here were made possible by the development of two three-dimensional computer codes. The first (PARA) systematically searches for parasitic oscillations in slab lasers and determines the gain required to reach threshold. Our second code (AMSPE) is a three dimensional raytrace model which includes temporal gain and allows for non-uniform gain profiles. AMSPE calculates the gain depletion as well as changes in spatial gain profile and thus the decrease in amplifier efficiency as a function of a number of critical parameters such as slab aspect ratio, spontaneous emission spectral profile, and slab face angle. In this paper we first review the classes of parasitics in slab lasers and show how symmetry breaking can significantly increase the energy storage capability of such deyices. We then review the construction of the AMSPE code and show how it may be used to identify maximum efficiency slab laser configurations.

  20. Spontaneous emission of electromagnetic and electrostatic fluctuations in magnetized plasmas: Quasi-parallel modes

    NASA Astrophysics Data System (ADS)

    Kim, Sunjung; Yoon, Peter H.; Choe, G. S.

    2016-02-01

    The present paper is devoted to the theoretical and numerical analysis of the spontaneously emitted electromagnetic fluctuations characterized by quasi-parallel wave vectors relative to the ambient magnetic field. The formulation is based upon the Klimontovich plasma kinetic theory. The comparative study is carried out between the spontaneously emitted field fluctuation spectrum constructed on the basis of a single Maxellian velocity distribution function (VDF) and the spectrum that arises from multi-component electron VDFs similar to those found in the solar wind. Typical solar wind electron VDF is composed of a Gaussian core and kappa distributions of halo and super-halo components. Of these, the halo and super-halo populations represent tenuous but energetic components. It is found that the energetic electrons make important contributions to the total emission spectrum. It is also found that the halo electrons are largely responsible for the emission spectrum in the whistler frequency range, whereas the more energetic super-halo electrons emit quasi-longitudinal fluctuations in the Langmuir frequency range, thus validating the recent quasi-steady state model of the solar wind electrons put forth by the present authors [Kim et al., Astrophys. J. 806, 32 (2015); Yoon et al., Astrophys. J. 812, 169 (2015)].

  1. Investigation of the spontaneous emission rate of perylene dye molecules encapsulated into three-dimensional nanofibers via FLIM method

    NASA Astrophysics Data System (ADS)

    Acikgoz, Sabriye; Demir, Mustafa M.; Yapasan, Ece; Kiraz, Alper; Unal, Ahmet A.; Inci, M. Naci

    2014-09-01

    The decay dynamics of perylene dye molecules encapsulated in polymer nanofibers produced by electrospinning of polymethyl methacrylate are investigated using a confocal fluorescence lifetime imaging microscopy technique. Time-resolved experiments show that the fluorescence lifetime of perylene dye molecules is enhanced when the dye molecules are encapsulated in a three-dimensional photonic environment. It is hard to produce a sustainable host with exactly the same dimensions all the time during fabrication to accommodate dye molecules for enhancement of spontaneous emission rate. The electrospinning method allows us to have a control over fiber diameter. It is observed that the wavelength of monomer excitation of perylene dye molecules is too short to cause enhancement within nanofiber photonic environment of 330 nm diameters. However, when these nanofibers are doped with more concentrated perylene, in addition to monomer excitation, an excimer excitation is generated. This causes observation of the Purcell effect in the three-dimensional nanocylindrical photonic fiber geometry.

  2. Performance of a quantum teleportation protocol based on collective spontaneous emission

    SciTech Connect

    Wagner, Richard Jr.; Clemens, James P.

    2009-03-15

    Recently a conditional quantum teleportation protocol has been proposed by Chen et al. [New J. Phys. 7, 172 (2005)], which is based on the collective spontaneous emission of a photon from a pair of quantum dots. We formulate a similar protocol for collective emission from a pair of atoms, one of which is entangled with a single mode of an optical cavity. We focus on the performance of the protocol as characterized by the fidelity of the teleported state and the overall success probability. We consider a strategy employing spatially resolved photodetection of the emitted photon in order to distinguish superradiant from subradiant emission on the basis of a single detected photon. We find that fidelity approaches unity as the spacing of the atoms becomes much smaller than the emission wavelength with a success probability of 0.25. The fidelity remains above the classical limit of 2/3 for arbitrary atomic separations with the ultimate limit of performance coming from the spatial resolution of the detectors.

  3. USER'S GUIDE: EMISSION CONTROL TECHNOLOGIES AND EMISSION FACTORS FOR UNPAVED ROAD FUGITIVE EMISSIONS

    EPA Science Inventory

    This document assists control agency personnel in evaluating unpaved road fugitive emissions control plans and helps industry personnel develop effective control strategies for unpaved roads. he brochure describes control techniques for reducing unpaved road emissions and methods...

  4. Spontaneous Emission Between - and Para-Levels of Water-Ion H_2O^+

    NASA Astrophysics Data System (ADS)

    Tanaka, Keiichi; Harada, Kensuke; Nanbu, Shinkoh; Oka, Takeshi

    2012-06-01

    Nuclear spin conversion interaction of water ion, H_2O^+, has been studied to derive spontaneous emission lifetime between ortho- and para-levels. H_2O^+ is a radical ion with the ^2B_1 electronic ground state. Its off-diagonal electron spin-nuclear spin interaction term, Tab(S_a? I_b + S_b? I_a), connects para and ortho levels, because ? I = I_1 - I_2 has nonvanishing matrix elements between I = 0 and 1. The mixing by this term with Tab = 72 MHz predicted by ab initio theory in the MRD-CI/Bk level, is many orders of magnitude larger than for closed shell molecules because of the large magnetic interaction due to the un-paired electron. Using the molecular constants reported by Mrtz et al. by FIR-LMR, we searched for ortho and para coupling channels below 1000 cm-1 with accidental near degeneracy between para and ortho levels. For example, hyperfine components of the 42,2(ortho) and 33,0(para) levels mix by 1.2 10-3 due to their near degeneracy (? E = 0.417 cm-1), and give the ortho-para spontaneous emission lifetime of about 0.63 year. The most significant low lying 10,1(para) and 11,1(ortho) levels, on the contrary, mix only by 8.7 10-5 because of their large separation (? E = 16.267 cm-1) and give the spontaneous emission lifetime from 10,1(para) to 00,0(ortho) of about 100 year.These results qualitatively help to understand the observed high ortho- to para- H_2O^+ ratio of 4.8 0.5 toward Sgr B2 but they are too slow to compete with the conversion by collision unless the number density of the region is very low (n 1 cm-3) or radiative temperature is very high (T_r > 100 K). M. Staikova, B. Engels, M. Peric, and S.D. Peyerimhoff, Mol. Phys. 80, 1485 (1993) P. Mrtz, L.R. Zink, K.M. Evenson, and J.M. Brown J. Chem. Phys. 109, 9744 (1998). LP. Schilke, et al., A&A 521, L11 (2010).

  5. Final LDRD report : enhanced spontaneous emission rate in visible III-nitride LEDs using 3D photonic crystal cavities.

    SciTech Connect

    Fischer, Arthur Joseph; Subramania, Ganapathi S.; Coley, Anthony J.; Lee, Yun-Ju; Li, Qiming; Wang, George T.; Luk, Ting Shan; Koleske, Daniel David; Fullmer, Kristine Wanta

    2009-09-01

    The fundamental spontaneous emission rate for a photon source can be modified by placing the emitter inside a periodic dielectric structure allowing the emission to be dramatically enhanced or suppressed depending on the intended application. We have investigated the relatively unexplored realm of interaction between semiconductor emitters and three dimensional photonic crystals in the visible spectrum. Although this interaction has been investigated at longer wavelengths, very little work has been done in the visible spectrum. During the course of this LDRD, we have fabricated TiO{sub 2} logpile photonic crystal structures with the shortest wavelength band gap ever demonstrated. A variety of different emitters with emission between 365 nm and 700 nm were incorporated into photonic crystal structures. Time-integrated and time-resolved photoluminescence measurements were performed to measure changes to the spontaneous emission rate. Both enhanced and suppressed emission were demonstrated and attributed to changes to the photonic density of states.

  6. Readiness potentials preceding spontaneous motor acts: voluntary vs. involuntary control.

    PubMed

    Keller, I; Heckhausen, H

    1990-10-01

    Libet et al. (1983) developed a method to compare the onset time of a readiness potential (RP) with the onset time of the corresponding intention to perform a spontaneous voluntary motor act. In relation to the onset of the RP, the time of conscious intention to move followed 350 msec later. From these results Libet (1985) concluded that the cerebral initiation of a spontaneous voluntary act begins unconsciously. We investigated the alternative interpretation that with the instruction to pay attention to feelings of 'wanting to move,' automatic and normally unconscious motor acts might have been brought to a level of conscious awareness. Therefore we conducted 3 kinds of experiment. In the first, RPs were measured from subjects performing unconscious movements. The second experiment was a replication of Libet's study while the third was a resting condition in which subjects looked for intentions to move introspectively. The results showed that RPs beginning approximately 500 msec before movement onset can be obtained with unconsciously as well as consciously performed spontaneous motor acts. The different scalp distributions of the two types of RP indicate that unconscious movements can be attributed to the activation of a contralateral process (lateral premotor system (LPS), primary motor cortex), whereas voluntary spontaneous motor acts seemed to be predominated by the medial premotor system (MPS). It is proposed that in the Libet situation focused attention on internal events led to the conscious detection of a normally unconscious process. This resulted in the activation of the MPS, especially the supplementary motor area (SMA), which released the starting signal for the execution of the motor act. We believe that the activation of the SMA and the urge to move occurred at the same time. PMID:1699728

  7. Enhanced amplified spontaneous emission using layer-by-layer assembled cowpea mosaic virus

    NASA Astrophysics Data System (ADS)

    Li, Na; Deng, Zhaoqi; Lin, Yuan; Zhang, Xiaojie; Geng, Yanhou; Ma, Dongge; Su, Zhaohui

    2009-01-01

    Layer-by-layer assembly technique was used to construct ultrathin film of cowpea mosaic virus (CPMV) by electrostatic interactions, and the film was employed as a precursor on which an OF8T2 film was deposited by spin coating. Amplified spontaneous emission (ASE) was observed and improved for the OF8T2 film. Compared with OF8T2 film on quartz, the introduction of CPMV nanoparticles reduced the threshold and loss, and remarkably increased the net gain. The threshold, loss, and gain reached 0.05 mJ/pulse, 6.9 cm-1, and 82 cm-1, respectively. CPMV nanoparticles may enormously scatter light, resulting in a positive feedback, thus the ASE is easily obtained and improved.

  8. Influence of the neodymium glass parameters on the amplified spontaneous emission in slab amplifier

    NASA Astrophysics Data System (ADS)

    Wang, Bingyan; Zhang, Junyong; Zhang, Yanli; Wang, Li; Zhu, Jianqiang

    2015-02-01

    Amplified spontaneous emission (ASE) causes the decrease of the inverted population density and the nonuniformity of gain in slab amplifier for high power laser systems. In this paper, a three dimension model, based on the data in SG-II, in which the residual reflection in the cladding and the ASE process are taken into consideration, is built to analyze the space distribution and time evolution of small signal gain coefficient using Monte Carlo algorithm and ray tracing. This model has been verified by comparing with the experimental data. The traverse size of slab is 68.2cm×36.3cm, which is usually decided by the clear aperture and the manufacture. By means of the model, the impact of thickness, residual reflectivity and the stimulated cross section of neodymium glass to the ASE are analyzed in detail.

  9. Spontaneous emission rate and optical amplification of Er3+ in double slot waveguide

    NASA Astrophysics Data System (ADS)

    Wang, XingJun; Jiang, LingJun; Guo, RuiMin; Ye, Rui; Zhou, ZhiPing

    2015-12-01

    The spontaneous emission (SE) of Er3+ embedded in a double slot dielectric structure was studied by a quantum-electrodynamical formalism. The study shows that the slot width and the position of Er3+ in slot structure have a significant effect on the SE. The double slot waveguides were fabricated by embedding two low-index Er/Yb silicate material layers into high-index silicon. The radiative efficiency of Er3+ in the double slot waveguides is found to be higher than that of the single slot waveguide, which is consistent with the theory simulation. The 0.67 dB signal enhancement at 1.53 m in a 4.6-mm-long slot waveguide was observed pumped by 1476 nm laser. These results show the relevance of our model to study the SE processes in multilayer structures and are important for future realization of silicon-compatible active optical devices.

  10. High-power thulium-doped all-fibre amplified spontaneous emission sources

    NASA Astrophysics Data System (ADS)

    Jin, Xiaoxi; Wang, Xiong; Xu, Jiangming; Wang, Xiaolin; Zhou, Pu

    2015-04-01

    We demonstrate high-power thulium-doped all-fibre amplified spontaneous emission (ASE) sources operating at ~2 ?m with both broadband and narrowband spectra based on thulium-doped fibre master oscillator power amplifier configuration. The maximum output power of broadband thulium-doped all-fibre ASE source reached 316 W with the spectral full width at half maximum (FWHM) of 24 nm and the slope efficiency of 53%. The maximum output power of 292 W and the FWHM of 1.5 nm were obtained with the slope efficiency of 56% in narrowband thulium-doped all-fibre ASE source. To the best of our knowledge, this is the highest output power of both broadband and narrowband all-fibre ASE sources operating at 2 ?m. Output power could be further enhanced via increasing pump power and/or employing better cooling management.

  11. Spatially-selective amplified spontaneous emission source derived from an ultrahigh gain solid-state amplifier.

    PubMed

    Smith, G; Damzen, M J

    2006-04-17

    An investigation is made into the performance of a high power solid-state amplified spontaneous emission (ASE) source with near-diffraction-limited beam quality. The radiation from this ASE source has high spatial quality and power, but unlike a laser it has a high misalignment tolerance and does not require a precisely aligned cavity. The source is based on a diode-pumped Nd:YVO4 laser crystal in a bounce amplifier geometry with a uniquely ultra-high gain (~104-105). Double-pass ASE radiation with high power levels (>6W) is achieved in a near-diffraction-limited spatial quality. We further demonstrate that the double-pass ASE source also displays high spatial selectivity and capability to compensate for a phase diffuser, inserted in the double-pass arm, with only a small degradation in beam quality and power. PMID:19516475

  12. Ultrabroadband ghost imaging exploiting optoelectronic amplified spontaneous emission and two-photon detection.

    PubMed

    Hartmann, Sbastien; Molitor, Andreas; Elser, Wolfgang

    2015-12-15

    Ghost imaging (GI) is one of the recent fascinating and probably counterintuitive topics of quantum optics. Here, we present an alternative classical GI scheme using spectrally ultrabroadband amplified spontaneous emission from an optoelectronic quantum dot based superluminescent diode source. This light source exhibits highly incoherent properties regarding both first- and second-order correlations with a 70nm-wide optical spectrum as well as thermal-like photon statistics. Exploiting a two-photon-absorption detection method, we demonstrate for the first time, to the best of our knowledge, a GI experiment handling the corresponding femtosecond correlation timescales. By introducing compact broadband light sources to GI, this work contributes toward practical application of GI. PMID:26670508

  13. Photo-physical properties and amplified spontaneous emission of a new derivative of fluorescein

    NASA Astrophysics Data System (ADS)

    Al-Shamiri, Hamdan A. S.; Kana, Maram T. H. Abou; Azzouz, I. M.; Elwahy, Ahmed H. M.

    2010-04-01

    The synthesis of new high-performance dyes and the implementation of new ways of incorporating the organic molecules into the solid host matrices have produced a great deal of activity in the field of solid-state dye lasers. In this article, the new laser dye, 2-(6-allyl-3-oxo-3H-xanthen-9-yl)-benzoic acid ethyl ester [AXBE] has been synthesized, and its chemical structure was confirmed by 1H NMR, 13C NMR, IR and elemental analysis. This new dye was covalently bonded with methyl methacrylate (MMA) and 2-hydroxy ethyl methacrylate (HEMA) copolymer backbone and evaluated as the active medium of the solid-state laser dye. Its optical properties were experimentally investigated. Amplified spontaneous emission (ASE) and photostability were studied by pumping the dye sample with 355 nm (8 ns) pulsed Nd-YAG laser.

  14. Computational analysis of the amplified spontaneous emission in quantum dot doped plastic optical fibers

    NASA Astrophysics Data System (ADS)

    Peng, Xuefeng; Wu, Pinghui; Han, Yinxia; Hu, Guoqiang

    2014-11-01

    The properties of amplified spontaneous emission (ASE) in CdSe/ZnS quantum dot (QD) doped step-index polymer optical fibers (POFs) were computationally analyzed in this paper. A theoretical model based on the rate equations between two main energy levels of CdSe/ZnS QD was built in terms of time (t), distance traveled by light (z) and wavelength (?), which can describe the ASE successfully. Through analyzing the spectral evolution with distance of the pulses propagating along the CdSe/ZnS QD doped POFs, dependences of the ASE threshold and the slope efficiency on the numerical aperture were obtained. Compared to the ASE in common dye-doped POFs, the pump threshold was just about 1/1000, but the slope efficiency was much higher.

  15. Spontaneous Hot-Electron Light Emission from Electron-Fed Optical Antennas.

    PubMed

    Buret, Mickael; Uskov, Alexander V; Dellinger, Jean; Cazier, Nicolas; Mennemanteuil, Marie-Maxime; Berthelot, Johann; Smetanin, Igor V; Protsenko, Igor E; Colas-des-Francs, Gérard; Bouhelier, Alexandre

    2015-09-01

    Nanoscale electronics and photonics are among the most promising research areas providing functional nanocomponents for data transfer and signal processing. By adopting metal-based optical antennas as a disruptive technological vehicle, we demonstrate that these two device-generating technologies can be interfaced to create an electronically driven self-emitting unit. This nanoscale plasmonic transmitter operates by injecting electrons in a contacted tunneling antenna feedgap. Under certain operating conditions, we show that the antenna enters a highly nonlinear regime in which the energy of the emitted photons exceeds the quantum limit imposed by the applied bias. We propose a model based upon the spontaneous emission of hot electrons that correctly reproduces the experimental findings. The electron-fed optical antennas described here are critical devices for interfacing electrons and photons, enabling thus the development of optical transceivers for on-chip wireless broadcasting of information at the nanoscale. PMID:26214575

  16. Temporal phase mask encrypted optical steganography carried by amplified spontaneous emission noise.

    PubMed

    Wu, Ben; Wang, Zhenxing; Shastri, Bhavin J; Chang, Matthew P; Frost, Nicholas A; Prucnal, Paul R

    2014-01-13

    A temporal phase mask encryption method is proposed and experimentally demonstrated to improve the security of the stealth channel in an optical steganography system. The stealth channel is protected in two levels. In the first level, the data is carried by amplified spontaneous emission (ASE) noise, which cannot be detected in either the time domain or spectral domain. In the second level, even if the eavesdropper suspects the existence of the stealth channel, each data bit is covered by a fast changing phase mask. The phase mask code is always combined with the wide band noise from ASE. Without knowing the right phase mask code to recover the stealth data, the eavesdropper can only receive the noise like signal with randomized phase. PMID:24515055

  17. Systematic study of spontaneous emission in a two-dimensional arbitrary inhomogeneous environment

    SciTech Connect

    Qiao Pengfei; Sha, Wei E. I.; Choy, Wallace C. H.; Chew, Weng Cho

    2011-04-15

    The spontaneous emission (SE) of the excited atoms in a two-dimensional (2D) arbitrary inhomogeneous environment has been systematically studied. The local density of states, which determines the radiation dynamics of a point source (for 3D) or a line source (for 2D), in particular, the SE rate, is represented by the electric dyadic Green's function. The numerical solution of the electric Green's tensor has been accurately obtained with the finite-difference frequency-domain method with the proper approximations of the monopole and dipole sources. The SE of atoms in photonic crystal and plasmonic metal plates has been comprehensively and comparatively investigated. For both the photonic crystal and plasmonic plates systems, the SEs depend on their respective dispersion relations and could be modified by the finite-structure or finite-size effects. This work is important for SE engineering and the optimized design of optoelectronic devices.

  18. Spontaneous emission of radiation by relativistic electrons in a gyro-klystron

    NASA Astrophysics Data System (ADS)

    Mishra, G.; Prakash, Bramha; Sharma, Geetanjali

    2016-03-01

    In this paper, we study spontaneous emission of radiation by relativistic electrons in a gyro-klystron. The scheme consists of two solenoid sections separated by a dispersive section. In the dispersive section the electrons are made non resonant with the radiation. The dispersive section transforms a small change of the velocity into changes of the phases of the electrons.This leads to enhanced radiation as compared to a conventional gyrotron type device driven by cyclotron maser interaction. It is shown that the klystron modulated spectrum depends on the dispersive field strength, finite perpendicular velocity component and length of the solenoids but do not depend on the axial magnetic field strength. The analysis is further extended to include the combined effects of the undulator aided gyrotron klystron radiation.

  19. Exhaust emission control and diagnostics

    DOEpatents

    Mazur, Christopher John; Upadhyay, Devesh

    2006-11-14

    A diesel engine emission control system uses an upstream oxidation catalyst and a downstream SCR catalyst to reduce NOx in a lean exhaust gas environment. The engine and upstream oxidation catalyst are configured to provide approximately a 1:1 ratio of NO to NO2 entering the downstream catalyst. In this way, the downstream catalyst is insensitive to sulfur contamination, and also has improved overall catalyst NOx conversion efficiency. Degradation of the system is determined when the ratio provided is no longer near the desired 1:1 ratio. This condition is detected using measurements of engine operating conditions such as from a NOx sensor located downstream of the catalysts. Finally, control action to adjust an injected amount of reductant in the exhaust gas based on the actual NO to NO2 ratio upstream of the SCR catalyst and downstream of the oxidation catalyst.

  20. Gravity Wave Emission by Spontaneous Imbalance of Baroclinic Waves in the Continuously Stratified Rotating Annulus

    NASA Astrophysics Data System (ADS)

    Borchert, Sebastian; Achatz, Ulrich; Rieper, Felix; Fruman, Mark

    2013-04-01

    We use a numerical model of the classic differentially heated rotating annulus experiment to study the spontaneous emission of gravity waves (GWs) from jet stream imbalances, which is a major source of these waves in the atmosphere for which no satisfactory parameterization exists. Atmospheric observations are the main tool for the testing and verification of theoretical concepts but have their limitations. Given their specific potential for yielding reproducible data and for studying process dependence on external system parameters, laboratory experiments are an invaluable complementary tool. Experiments with a rotating annulus exhibiting a jet modulated by large-scale waves due to baroclinic instability have already been used to study GWs: Williams et al (2008) observed spontaneously emitted interfacial GWs in a two-layer flow, and Jacoby et al (2011) detected GWs emitted from boundary-layer instabilities in a differentially heated rotating annulus. Employing a finite-volume code for the numerical simulation of a continuously stratified liquid in a differentially heated rotating annulus, we here investigate the GWs in a wide and shallow annulus with relatively large temperature difference between inner and outer cylinder walls. In this atmosphere-like regime where the Brunt-Vaisala frequency is larger than the inertial frequency, various analyses suggest a distinct gravity wave activity. To identify regions of GW emission we decompose the flow into the geostrophic and ageostrophic part through the inversion of the quasi-geostrophic potential vorticity (e.g. Verkley, 2009). The analysis of the geostrophic sources of the ageostrophic flow indicates that, in addition to boundary layer instabilities, spontaneous imbalance in the jet region acts as an important source mechanism. Jacoby, T. N. L., Read, P. L., Williams, P. D. and Young, R. M. B., 2011: Generation of inertia-gravity waves in the rotating thermal annulus by a localised boundary layer instability. Geophys. Astrophys. Fluid Dyn., 105, 161-181. Doi:10.1080/03091929.2011.560151 Verkley, W.T.M., 2009: A balanced approximation of the one-layer shallow-water equations on a sphere. J. Atmos. Sci., 66, 1735-1748. Doi:10.1175/2008JAS2837.1 Williams, P. D., Haine, T. W. N. and Read, P. L., 2008: Inertia-gravity waves emitted from balanced flow: observations, properties, and consequences. J. Atmos. Sci., 65, 3543-3556. Doi:10.1175/2008JAS2480.1

  1. Spontaneous and stimulated emission from Cd{sub x}Hg{sub 1-x} Te semiconductor films

    SciTech Connect

    Andronov, A. A.; Nozdrin, Yu. N.; Okomel'kov, A. V. Varavin, V. S. Smirnov, R. N.; Ikusov, D. G.

    2006-11-15

    The experimental data on observation of spontaneous and stimulated emission from thin epitaxial Cd{sub x}Hg{sub 1-x} Te films optically pumped by Nd: YAG laser radiation are reported. A simple theoretical model is suggested to describe the initiation of population inversion under these conditions. The parameters realized under the experimental conditions are theoretically estimated.

  2. EFFECTS OF INSTILLED EMISSION PARTICULATE MATTER ON ELECTROCARDIOGRAPHIC INDICES AND HEART RATE VARIABILITY (HRV) IN SPONTANEOUSLY HYPERTENSIVE RATS

    EPA Science Inventory

    EFFECTS OF INSTILLED EMISSION PARTICULATE MATTER (EPM) ON ELECTROCARDIOGRAPHIC INDICES AND HEART RATE VARIABILITY (HRV) IN SPONTANEOUSLY HYPERTENSIVE (SH) RATS. L.B. Wichers1, J.P. Nolan2, W.H. Rowan2, M.J. Campen3, T.P. Jenkins4, D.L. Costa2, and W.P. Watkinson2. 1UNC SPH, Chap...

  3. Spectroscopic properties and amplified spontaneous emission of fluorescein laser dye in ionic liquids as green media

    NASA Astrophysics Data System (ADS)

    AL-Aqmar, Dalal M.; Abdelkader, H. I.; Abou Kana, Maram T. H.

    2015-09-01

    The use of ionic liquids (ILs) as milieu materials for laser dyes is a promising field and quite competitive with volatile organic solvents and solid state-dye laser systems. This paper investigates some photo-physical parameters of fluorescein dye incorporated into ionic liquids; 1-Butyl-3-methylimidazolium chloride (BMIM Cl), 1-Butyl-3-methylimidazolium tetrachloroaluminate (BMIM AlCl4) and 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4) as promising host matrix in addition to ethanol as reference. These parameters are: absorption and emission cross-sections, fluorescence lifetime and quantum yield, in addition to the transition dipole moment, the attenuation length and oscillator strength were also investigated. Lasing characteristics such as amplified spontaneous emission (ASE), the gain, and the photostability of fluorescein laser dye dissolved in different host materials were assessed. The composition and properties of the matrix of ILs were found that it has great interest in optimizing the laser performance and photostability of the investigated laser dye. Under transverse pumping of fluorescein dye by blue laser diode (450 nm) of (400 mW), the initial ASE for dye dissolved in BMIM AlCl4 and ethanol were decreased to 39% and 36% respectively as time progressed 132 min. Relatively high efficiency and high fluorescence quantum yield (11.8% and 0.82% respectively) were obtained with good photostability in case of fluorescein in BMIM BF4 that was decreased to ?56% of the initial ASE after continuously pumping with 400 mW for 132 min.

  4. Accurate binaural mirroring of spontaneous otoacoustic emissions suggests influence of time-locking in medial efferents.

    PubMed

    Braun, M

    1998-04-01

    Spontaneous otoacoustic emissions (SOAEs) of nearly identical acoustic frequency in both ears are a common observation, but it is unknown if this binaural mirroring effect is random, artefactual, genetic, developmental, or of other origin. The available raw data of all human SOAE surveys were pooled, and the intervals of all possible binaural emission pairs (N = 9555) were listed according to size on the Cent-scale (1 Cent = 1/100 semitone = 1/1200 octave). Statistical analysis showed (1) a slight broad-band mirroring in the 0-100 Cent range (P < 0.05), and (2) a strong narrow-band mirroring (NBM) in the 0-20 Cent range (P < 0.001). Negative results in a detailed SOAE cluster detection program excluded experimental artefacts as causes of NBM. Analysis of the large subgroup of twin data excluded genetic and intrauterine developmental causes. Systemic developmental causes are unrealistic, as 20 Cent corresponds to only approximately 80 microm on the cochlear map. Analysis of infant data indicated that the effect may be introduced after birth by secondary factors. Interaural crosstalk was examined but had to be rejected. It is suggested that bilaterally spreading period information in the medial olivocochlear system influences outer hair cells of the same best frequency in both ears very similarly. Evidence concerning possible effects on electromotility is discussed, and experimental tests are proposed. PMID:9606068

  5. Standoff detection of nitrotoluenes using 213-nm amplified spontaneous emission from nitric oxide.

    PubMed

    Arnold, Bradley; Kelly, Lisa; Oleske, Jeffrey B; Schill, Alexander

    2009-09-01

    A method of standoff detection based on the observation of laser-induced fluorescence-amplified spontaneous emission (LIF-ASE) is described. LIF-ASE generates uniaxial intensity distributions of the observed fluorescence with the majority of intensity propagating along the excitation axis in both the forward and backward directions. The detection of bulk vapor at significant standoff distances is readily achieved. This method was used to detect NO directly and as a photoproduct after 213-nm excitation of 2-, 3-, and 4-nitrotoluene. The NO LIF-ASE spectra were studied as a function of buffer gas. These studies showed that the emission from different vibrational states was dependent upon the buffer gas used, suggesting that the populations of vibrational states were influenced by the environment. A similar sensitivity of the vibrational populations was observed when the different nitroaromatic precursors were used in nitrogen buffer gas. Such sensitivity to environmental influences can be used to distinguish among the different nitroaromatic precursors and facilitate the identification of the bulk vapor of these analytes. PMID:19649618

  6. Mammalian spontaneous otoacoustic emissions are amplitude-stabilized cochlear standing waves.

    PubMed

    Shera, Christopher A

    2003-07-01

    Mammalian spontaneous otoacoustic emissions (SOAEs) have been suggested to arise by three different mechanisms. The local-oscillator model, dating back to the work of Thomas Gold, supposes that SOAEs arise through the local, autonomous oscillation of some cellular constituent of the organ of Corti (e.g., the "active process" underlying the cochlear amplifier). Two other models, by contrast, both suppose that SOAEs are a global collective phenomenon--cochlear standing waves created by multiple internal reflection--but differ on the nature of the proposed power source: Whereas the "passive" standing-wave model supposes that SOAEs are biological noise, passively amplified by cochlear standing-wave resonances acting as narrow-band nonlinear filters, the "active" standing-wave model supposes that standing-wave amplitudes are actively maintained by coherent wave amplification within the cochlea. Quantitative tests of key predictions that distinguish the local-oscillator and global standing-wave models are presented and shown to support the global standing-wave model. In addition to predicting the existence of multiple emissions with a characteristic minimum frequency spacing, the global standing-wave model accurately predicts the mean value of this spacing, its standard deviation, and its power-law dependence on SOAE frequency. Furthermore, the global standing-wave model accounts for the magnitude, sign, and frequency dependence of changes in SOAE frequency that result from modulations in middle-ear stiffness. Although some of these SOAE characteristics may be replicable through artful ad hoc adjustment of local-oscillator models, they all arise quite naturally in the standing-wave framework. Finally, the statistics of SOAE time waveforms demonstrate that SOAEs are coherent, amplitude-stabilized signals, as predicted by the active standing-wave model. Taken together, the results imply that SOAEs are amplitude-stabilized standing waves produced by the cochlea acting as a biological, hydromechanical analog of a laser oscillator. Contrary to recent claims, spontaneous emission of sound from the ear does not require the autonomous mechanical oscillation of its cellular constituents. PMID:12880039

  7. PARTICULATE EMISSION MEASUREMENTS FROM CONTROLLED CONSTRUCTION ACTIVITIES

    EPA Science Inventory

    The report summarized the results of field testing of the effectiveness of control measures for sources of fugitive particulate emissions found at construction sites. The effectiveness of watering temporary, unpaved travel surfaces on emissions of particulate matter with aerodyna...

  8. Brain modularity controls the critical behavior of spontaneous activity

    NASA Astrophysics Data System (ADS)

    Russo, R.; Herrmann, H. J.; de Arcangelis, L.

    2014-03-01

    The human brain exhibits a complex structure made of scale-free highly connected modules loosely interconnected by weaker links to form a small-world network. These features appear in healthy patients whereas neurological diseases often modify this structure. An important open question concerns the role of brain modularity in sustaining the critical behaviour of spontaneous activity. Here we analyse the neuronal activity of a model, successful in reproducing on non-modular networks the scaling behaviour observed in experimental data, on a modular network implementing the main statistical features measured in human brain. We show that on a modular network, regardless the strength of the synaptic connections or the modular size and number, activity is never fully scale-free. Neuronal avalanches can invade different modules which results in an activity depression, hindering further avalanche propagation. Critical behaviour is solely recovered if inter-module connections are added, modifying the modular into a more random structure.

  9. Brain modularity controls the critical behavior of spontaneous activity.

    PubMed

    Russo, R; Herrmann, H J; de Arcangelis, L

    2014-01-01

    The human brain exhibits a complex structure made of scale-free highly connected modules loosely interconnected by weaker links to form a small-world network. These features appear in healthy patients whereas neurological diseases often modify this structure. An important open question concerns the role of brain modularity in sustaining the critical behaviour of spontaneous activity. Here we analyse the neuronal activity of a model, successful in reproducing on non-modular networks the scaling behaviour observed in experimental data, on a modular network implementing the main statistical features measured in human brain. We show that on a modular network, regardless the strength of the synaptic connections or the modular size and number, activity is never fully scale-free. Neuronal avalanches can invade different modules which results in an activity depression, hindering further avalanche propagation. Critical behaviour is solely recovered if inter-module connections are added, modifying the modular into a more random structure. PMID:24621482

  10. Coherent coupling and modified spontaneous emission of a single ion in a high finesse optical cavity

    NASA Astrophysics Data System (ADS)

    Becher, Christoph

    2003-05-01

    thanksIn collaboration with A. Kreuter, A.B. Mundt, C. Russo, H. Hffner, C. Roos, J. Eschner, F. Schmidt-Kaler and R. Blatt, Institut fr Experimentalphysik, Universitt Innsbruck, Technikerstrae 25, A-6020 Innsbruck, Austria. Laser-cooled trapped atoms or ions are ideally suited systems for storing and processing quantum information. The transport of this quantum information over large distances via photons requires an interface between atoms and photons (J.I. Cirac et al., Phys. Rev. Lett. 78, 3221 (1997)). Such an interface is based on the deterministic coherent coupling of a single atom or ion to macroscopic and vacuum fields inside a high finesse optical cavity. Here, we perform two experiments to investigate such an interaction of a single Ca^+ ion and a cavity field: first, we excite Rabi oscillations with short resonant laser pulses injected into the cavity, and second, we measure the modification of the spontaneous emission rate from the metastable D_5/2 level induced by the cavity-enhanced vacuum field. The ^40Ca^+ ion is stored in a spherical Paul trap placed in the center of a high finesse near-confocal resonator (Finesse approx. 30.000 at 729 nm). The ion is laser-cooled to the Lamb-Dicke regime, confining its spatial wave packet to a region much smaller than the optical wavelength. We stabilize the cavity to the S_1/2 - D_5/2 quadrupole transition frequency (wavelength: 729 nm) using a transfer lock technique (A.B. Mundt et al., Appl. Phys. B, in press). To demonstrate coherent coupling of the ion and a macroscopic cavity field, we inject resonant laser pulses of different pulse lengths at 729 nm into the cavity and record the excitation on the S_1/2 - D_5/2 transition via the electron shelving technique. We observe a Rabi oscillation frequency of up to 9 MHz when the ion is placed in a node of the cavity standing wave field. (Rabioscillations) For the measurement of the cavity modified spontaneous emission (Purcell effect), we repeat the following sequence for 1oo times: first, we excite the ion with a ?-pulse on the S_1/2 - D_5/2 transition. We then detect whether the excitation was successful (electron shelving), wait for a certain delay time and measure the D_5/2 population again. Every second experimental run, we shift the cavity by approx. 5 linewidths away from resonance. By repeating this procedure for many times we infer the spontaneous decay rate from the metastable level for the cavity on resonance and off resonance (equivalent to free space emission), thus excluding systematic errors due to environmental effects. For the free-space lifetime we measure a value of 1129(19) ms, close to the currently most precisely measured value of 1168 ms (P. Barton et al., Phys. Rev. A 62, 032503 (2000)). First experiments with a delay time of 90 ms show a lifetime reduction of approx. 10% on resonance. 78, l. Phys. B, in pr ess.

  11. CONTROL OF COPPER SMELTER FUGITIVE EMISSIONS

    EPA Science Inventory

    This report deals with fugitive emissions from copper smelting and with related emission control measures. The study involved evaluation of the controls now used in the copper smelting industry and development of suggestions for alternative control devices and practices. A brief ...

  12. Loss of the Tectorial Membrane Protein CEACAM16 Enhances Spontaneous, Stimulus-Frequency, and Transiently Evoked Otoacoustic Emissions

    PubMed Central

    Goodyear, Richard J.; Homma, Kazuaki; Legan, P. Kevin; Korchagina, Julia; Naskar, Souvik; Siegel, Jonathan H.; Dallos, Peter; Zheng, Jing

    2014-01-01

    ?-Tectorin (TECTA), ?-tectorin (TECTB), and carcinoembryonic antigen-related cell adhesion molecule 16 (CEACAM) are secreted glycoproteins that are present in the tectorial membrane (TM), an extracellular structure overlying the hearing organ of the inner ear, the organ of Corti. Previous studies have shown that TECTA and TECTB are both required for formation of the striated-sheet matrix within which collagen fibrils of the TM are imbedded and that CEACAM16 interacts with TECTA. To learn more about the structural and functional significance of CEACAM16, we created a Ceacam16-null mutant mouse. In the absence of CEACAM16, TECTB levels are reduced, a clearly defined striated-sheet matrix does not develop, and Hensen's stripe, a prominent feature in the basal two-thirds of the TM in WT mice, is absent. CEACAM16 is also shown to interact with TECTB, indicating that it may stabilize interactions between TECTA and TECTB. Although brain-stem evoked responses and distortion product otoacoustic emissions are, for most frequencies, normal in young mice lacking CEACAM16, stimulus-frequency and transiently evoked emissions are larger. We also observed spontaneous otoacoustic emissions (SOAEs) in 70% of the homozygous mice. This incidence is remarkable considering that <3% of WT controls have SOAEs. The predominance of SOAEs >15 kHz correlates with the loss of Hensen's stripe. Results from mice lacking CEACAM16 are consistent with the idea that the organ of Corti evolved to maximize the gain of the cochlear amplifier while preventing large oscillations. Changes in TM structure appear to influence the balance between energy generation and dissipation such that the system becomes unstable. PMID:25080593

  13. Mono- to few-layered graphene oxide embedded randomness assisted microcavity amplified spontaneous emission source

    NASA Astrophysics Data System (ADS)

    Das, Pratyusha; Maiti, Rishi; Barman, Prahalad K.; Ray, Samit K.; Shivakiran, Bhaktha B. N.

    2016-02-01

    The realization of optoelectronic devices using two-dimensional materials such as graphene and its intermediate product graphene oxide (GO) is extremely challenging owing to the zero band gap of the former. Here, a novel amplified spontaneous emission (ASE) system based on a GO-embedded all-dielectric one-dimensional photonic crystal (1DPhC) micro-resonator is presented. The mono- to few-layered GO sheet is inserted within a microcavity formed by two 5-bilayered SiO2/SnO2 Bragg reflectors. Significantly enhanced photoluminescence (PL) emission of GO embedded in 1DPhC is explicated by studying the electric field confined within the micro-resonator using the transfer matrix method. The inherent randomness, due to fabrication limitations, in the on-average periodic 1DPhC is exploited to further enhance the PL of the optically active micro-resonator. The 1DPhC and randomness assisted field confinement reduces the ASE threshold of the mono- to few-layered weak emitter making the realization of an ASE source feasible. Consequently, ASE at the microcavity resonance and at the low-frequency band-edge of photonic stop-band is demonstrated. Variation of the detection angle from 5° to 30°, with respect to the sample surface normal allows reallocation of the defect mode ASE peak over a spectral range of 558–542 nm, making the GO-incorporated 1DPhC a novel and attractive system for integrated optic applications.

  14. Mono- to few-layered graphene oxide embedded randomness assisted microcavity amplified spontaneous emission source.

    PubMed

    Das, Pratyusha; Maiti, Rishi; Barman, Prahalad K; Ray, Samit K; Shivakiran, Bhaktha B N

    2016-02-01

    The realization of optoelectronic devices using two-dimensional materials such as graphene and its intermediate product graphene oxide (GO) is extremely challenging owing to the zero band gap of the former. Here, a novel amplified spontaneous emission (ASE) system based on a GO-embedded all-dielectric one-dimensional photonic crystal (1DPhC) micro-resonator is presented. The mono- to few-layered GO sheet is inserted within a microcavity formed by two 5-bilayered SiO2/SnO2 Bragg reflectors. Significantly enhanced photoluminescence (PL) emission of GO embedded in 1DPhC is explicated by studying the electric field confined within the micro-resonator using the transfer matrix method. The inherent randomness, due to fabrication limitations, in the on-average periodic 1DPhC is exploited to further enhance the PL of the optically active micro-resonator. The 1DPhC and randomness assisted field confinement reduces the ASE threshold of the mono- to few-layered weak emitter making the realization of an ASE source feasible. Consequently, ASE at the microcavity resonance and at the low-frequency band-edge of photonic stop-band is demonstrated. Variation of the detection angle from 5° to 30°, with respect to the sample surface normal allows reallocation of the defect mode ASE peak over a spectral range of 558-542 nm, making the GO-incorporated 1DPhC a novel and attractive system for integrated optic applications. PMID:26670725

  15. Measurements of amplified spontaneous emission in π-conjugated polymer films with different morphology

    NASA Astrophysics Data System (ADS)

    Wang, Yuchen; Yang, Xiao; Wang, Ruizhi; Sheng, Chuanxiang

    2014-09-01

    π-conjugated polymers (PCPs) are attractive candidates as gain media in laser applications due to their high photoluminescence quantum efficiency in broad spectral range. However, the self-absorption of long-lived excited states was considered to be a limitation for achieving more effective organic lasers. Moreover, the morphology of films is found to be crucial to their optical and electrical properties recently. In this work, we studied amplified spontaneous emission (ASE) of a typical PCP, namely, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) films with a 10 ns 532 nm pulse laser focused by a cylindrical lens for obtaining an excitation area in the form of a 100 μm wide and 1 cm long stripe. In an as cast MEH-PPV film, the thresholds increase with the temperatures increase due to the thermal torsion and vibration mode shorten the conjugation chain. On the other hand, a MEH-PPV film which is annealed in Nitrogen at 350 K of half hour, the ASE is not observed at both 300 K and 77 K, for annealing will form π- stacks which increase the interchain interaction. Further analysis suggests that interchain excimers instead of intrachain excitons may be more primary to optical properties in annealed MEH-PPV film. Our measurements suggest that the morphology of the film instead of long lived photoexcitation with lifetime sensitive to the temperature is more crucial to threshold of ASE, as well as, to PCPs lasers.

  16. Spontaneous emission dynamics in an omnidirectional waveguide made of photonic crystals

    NASA Astrophysics Data System (ADS)

    Huang, Chih-Hsien; Cheng, Szu-Cheng; Wu, Jing-Nuo; Hsieh, Wen-Feng

    2011-06-01

    The spontaneous emission dynamics of atoms embedded in an omnidirectional waveguide (ODWG), a novel optical waveguide, is studied on the basis of the complete reflection of one-dimensional photonic crystals. With the dispersion curve of the single waveguide mode within the photonic band gap and various extents of background dissipation, we characterize the photon-atom interaction in the ODWG. The photon emitter of the system is a two-level atom embedded in the low-index medium of the multilayer-film ODWG or the atom-ODWG system. Fractional calculus, an innovative mathematical method in optical systems, is applied to solve the equation of motion for this atom-ODWG system. Two kinds of states with different group velocities exhibit totally distinctive dynamical behavior. The high frequency waveguide mode with a fast group velocity shows fast exponential decay in propagation while the band-edge mode with a slow group velocity displays non-Markovian dynamics with non-exponential oscillating time evolution. We therefore suggest different functions of this atom-ODWG system for these two kinds of states. The richness of the physical content of the system is also revealed through investigating the dynamical behavior of the band-edge mode. These results aid in further application and fundamental understanding of the atom-ODWG system.

  17. Validity of the Relation Between Spontaneous and Stimulated Emissions in Semiconductors

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Saini, Subhash (Technical Monitor)

    1999-01-01

    The Einstein relation between spontaneous emission and absorption was originally derived for a system consists of a two-state subsystem representing matter and harmonic fields representing radiation. The derivation is based on the detailed balance between these two subsystems under thermal equilibrium. The relationship was later investigated in connection with the interactions between radiation field and solids or semiconductors. The simple derivation dose not hold for semiconductors in general. In certain limiting cases, simple relation was obtained. The validity of this relation is important not only because of its fundamental role connecting two of the most fundamental optical processes in semiconductors, but mostly also because of its wide use as a practical method to measure the optical gain of a semiconductor. The validity of this relation for semiconductors has been an issue of controversial for some time. In this paper we numerically examine the validity of this relationship for several different lineshapes including Lorentzian, Gaussian, Sech, and a convoluted double Lorentzians (CDL). We find out that at relatively low density above transparency level, all first three lineshapes violate the Einstein relation. The relation is approximately valid at high density. At very high density, the validity of the Einstein relation holds well for all three lineshapes. The reason behind this observation is explained. The CDL lineshape has been shown analytically to obey the Einstein relationship previously. We show that for a 2D semiconductor with parabolic bands, the CDL lineshape can be integrated analytically. This analytic lineshape is compared with a simple Lorentzian lineshape.

  18. Low-threshold amplified spontaneous emission and lasing from colloidal nanocrystals of caesium lead halide perovskites

    NASA Astrophysics Data System (ADS)

    Yakunin, Sergii; Protesescu, Loredana; Krieg, Franziska; Bodnarchuk, Maryna I.; Nedelcu, Georgian; Humer, Markus; de Luca, Gabriele; Fiebig, Manfred; Heiss, Wolfgang; Kovalenko, Maksym V.

    2015-08-01

    Metal halide semiconductors with perovskite crystal structures have recently emerged as highly promising optoelectronic materials. Despite the recent surge of reports on microcrystalline, thin-film and bulk single-crystalline metal halides, very little is known about the photophysics of metal halides in the form of uniform, size-tunable nanocrystals. Here we report low-threshold amplified spontaneous emission and lasing from ~10 nm monodisperse colloidal nanocrystals of caesium lead halide perovskites CsPbX3 (X=Cl, Br or I, or mixed Cl/Br and Br/I systems). We find that room-temperature optical amplification can be obtained in the entire visible spectral range (440-700 nm) with low pump thresholds down to 5+/-1 ?J cm-2 and high values of modal net gain of at least 450+/-30 cm-1. Two kinds of lasing modes are successfully observed: whispering-gallery-mode lasing using silica microspheres as high-finesse resonators, conformally coated with CsPbX3 nanocrystals and random lasing in films of CsPbX3 nanocrystals.

  19. Enhanced Amplified Spontaneous Emission in Perovskites Using a Flexible Cholesteric Liquid Crystal Reflector.

    PubMed

    Stranks, Samuel D; Wood, Simon M; Wojciechowski, Konrad; Deschler, Felix; Saliba, Michael; Khandelwal, Hitesh; Patel, Jay B; Elston, Steve J; Herz, Laura M; Johnston, Michael B; Schenning, Albertus P H J; Debije, Michael G; Riede, Moritz K; Morris, Stephen M; Snaith, Henry J

    2015-08-12

    Organic-inorganic perovskites are highly promising solar cell materials with laboratory-based power conversion efficiencies already matching those of established thin film technologies. Their exceptional photovoltaic performance is in part attributed to the presence of efficient radiative recombination pathways, thereby opening up the possibility of efficient light-emitting devices. Here, we demonstrate optically pumped amplified spontaneous emission (ASE) at 780 nm from a 50 nm-thick film of CH3NH3PbI3 perovskite that is sandwiched within a cavity composed of a thin-film (?7 ?m) cholesteric liquid crystal (CLC) reflector and a metal back-reflector. The threshold fluence for ASE in the perovskite film is reduced by at least two orders of magnitude in the presence of the CLC reflector, which results in a factor of two reduction in threshold fluence compared to previous reports. We consider this to be due to improved coupling of the oblique and out-of-plane modes that are reflected into the bulk in addition to any contributions from cavity modes. Furthermore, we also demonstrate enhanced ASE on flexible reflectors and discuss how improvements in the quality factor and reflectivity of the CLC layers could lead to single-mode lasing using CLC reflectors. Our work opens up the possibility of fabricating widely wavelength-tunable "mirror-less" single-mode lasers on flexible substrates, which could find use in applications such as flexible displays and friend or foe identification. PMID:25989354

  20. Nonequilibrium quantum fluctuations of a dispersive medium: Spontaneous emission, photon statistics, entropy generation, and stochastic motion

    NASA Astrophysics Data System (ADS)

    Maghrebi, Mohammad F.; Jaffe, Robert L.; Kardar, Mehran

    2014-07-01

    We study the implications of quantum fluctuations of a dispersive medium, under steady rotation, either in or out of thermal equilibrium with its environment. A rotating object exhibits a quantum instability by dissipating its mechanical motion via spontaneous emission of photons, as well as internal heat generation. Universal relations are derived for the radiated energy and angular momentum as trace formulas involving the object's scattering matrix. We also compute the quantum noise by deriving the full statistics of the radiated photons out of thermal and/or dynamic equilibrium. The (entanglement) entropy generation is quantified and the total entropy is shown to be always increasing. Furthermore, we derive a Fokker-Planck equation governing the stochastic angular motion resulting from the fluctuating backreaction frictional torque. As a result, we find a quantum limit on the uncertainty of the object's angular velocity in steady rotation. Finally, we show in some detail that a rotating object drags nearby objects, making them spin parallel to its axis of rotation. A scalar toy model is introduced to simplify the technicalities and ease the conceptual complexities and then a detailed discussion of quantum electrodynamics is presented.

  1. Spontaneous emission and Lamb shift in QED based on self-energy

    SciTech Connect

    Salamin, Y.I.H.

    1987-01-01

    This work consists of two parts. In the first part, a general fully relativistic formula is derived for the decay rates in atoms which reproduces the correct Einstein A coefficient of spontaneous emission when the dipole limit is taken. The derivation involves the evaluation of spin sums and angular and radial integrals performed in closed analytical form. When applied to the decay of the low-lying excited states of hydrogen and muonium, the formula gives results that are more precise than the most-recent perturbation-theory calculations and the experiments performed so far. In the second part, the self-energy contribution to the Lamb shift is taken up. Here, too, the new approach yields a formula that reduces to the famous logarithm of Bethe in the dipole approximation. All radial and angular integrations are performed exactly, and it is shown that the energy integral is well-behaved at both its ultra-violet and infrared ends. In this sense, the finiteness of the theory is demonstrated without the need for cutoffs or mass and charge renormalization. The final result is written as an expansion in powers of Z..cap alpha...

  2. Cold test, spontaneous emission and gain in a rectangular Cerenkov amplifier

    SciTech Connect

    Scharer, J.E.; Joe, J.; Booske, J.H.; Basten, M.; Kirolous, H.

    1994-12-31

    The authors present experimental results for the rectangular Cerenkov grating amplifier. This research is being carried out to develop a Ka-band (35 GHz), low voltage (10 kV), moderate power (10 kW) source. They have constructed a Ku-band grating structure to study a scaled version of this source. The tapered grating consists of two tapered Ku-band smooth wave guide sections and two 3.5-inch sections of five-step-tapered gratings. Both tapered and untapered grating structures have been cold tested utilizing the network analyzer measurements. They find that their taper design reduced the reflection coefficient from {minus}5 dB to less than {minus}20 dB over a 12--15 GHz bandwidth. Spontaneous emission results resulting from passing the circular electron beam from a Litton thermionic gun over the grating structure will be presented. They have theoretically investigated the sheet beam interaction with hybrid modes in a deep groove rectangular grating waveguide. A complex dispersion relation, which includes a finite axial energy spread of the beam, describing the interaction has been solved. The authors find that the instability is always convective in the forward wave mode regime.

  3. A novel two-stage erbium amplified spontaneous emission fiber source with 80nm bandwidth

    NASA Astrophysics Data System (ADS)

    Wang, Xiulin; Ming, Hai; Huang, Wencai

    2005-11-01

    In this paper, a practical two-stage scheme is suggested for generating a C+L-band erbium-doped fiber amplified spontaneous emission (ASE) broadband light source. A considerable power increase of the L-band ASE spectrum is achieved by injecting the C-band ASE into the long section erbium-doped fiber. The C+L-band ASE source is obtained by combining the enhanced L-band ASE with the C-band ASE from two stages respectively. A spectrum flat ASE source with nearly 80nm bandwidth and about 15.9dBm output power is obtained with a total pump power of 180mW. Namely, the pump conversion efficiency is about 21.6%. Such a broadband incoherent light source is desirable for various applications in some areas like sliced wavelength- division multiplexed local-access networks, characteristic measurement for dense wavelength-division multiplexed components, and fiber-optic sensor systems etc.

  4. Near infrared amplified spontaneous emission in a dye-doped polymeric waveguide for active plasmonic applications.

    PubMed

    Keshmarzi, Elham Karami; Tait, R Niall; Berini, Pierre

    2014-05-19

    Near-infrared amplified spontaneous emission (ASE) from an optically-pumped dye-doped polymeric slab waveguide, consisting of IR-140 in PMMA on a glass substrate, has been characterised. The ASE gain was measured using the variable stripe length method. Linewidth narrowing with increasing pump intensity was observed, indicating ASE gain in this material. The effects of the dye concentration and pump intensity on the gain were investigated under linear operation. The maximum achieved gain coefficient is γ ~68 cm(-1) for a film with 0.8 wt % of IR-140 to PMMA for a pump intensity of 43.4 mJ/cm(2). The polarisation dependence of the ASE gain was also investigated by measuring the gain coefficient of orthogonal TE and TM modes and varying the pump polarisation relative to the amplifier length. It was observed that there is some degree of gain anisotropy when the pump polarisation is aligned perpendicular to the length, but that the gain was isotropic when the pump polarisation is aligned parallel the length. The applicability of IR-140 doped PMMA for active plasmonic applications is discussed. PMID:24921362

  5. Low-threshold amplified spontaneous emission and lasing from colloidal nanocrystals of caesium lead halide perovskites

    PubMed Central

    Yakunin, Sergii; Protesescu, Loredana; Krieg, Franziska; Bodnarchuk, Maryna I.; Nedelcu, Georgian; Humer, Markus; De Luca, Gabriele; Fiebig, Manfred; Heiss, Wolfgang; Kovalenko, Maksym V.

    2015-01-01

    Metal halide semiconductors with perovskite crystal structures have recently emerged as highly promising optoelectronic materials. Despite the recent surge of reports on microcrystalline, thin-film and bulk single-crystalline metal halides, very little is known about the photophysics of metal halides in the form of uniform, size-tunable nanocrystals. Here we report low-threshold amplified spontaneous emission and lasing from ∼10 nm monodisperse colloidal nanocrystals of caesium lead halide perovskites CsPbX3 (X=Cl, Br or I, or mixed Cl/Br and Br/I systems). We find that room-temperature optical amplification can be obtained in the entire visible spectral range (440–700 nm) with low pump thresholds down to 5±1 μJ cm−2 and high values of modal net gain of at least 450±30 cm−1. Two kinds of lasing modes are successfully observed: whispering-gallery-mode lasing using silica microspheres as high-finesse resonators, conformally coated with CsPbX3 nanocrystals and random lasing in films of CsPbX3 nanocrystals. PMID:26290056

  6. Red, Yellow, Green, and Blue Amplified Spontaneous Emission and Lasing Using Colloidal CdSe Nanoplatelets.

    PubMed

    She, Chunxing; Fedin, Igor; Dolzhnikov, Dmitriy S; Dahlberg, Peter D; Engel, Gregory S; Schaller, Richard D; Talapin, Dmitri V

    2015-10-27

    There have been multiple demonstrations of amplified spontaneous emission (ASE) and lasing using colloidal semiconductor nanocrystals. However, it has been proven difficult to achieve low thresholds suitable for practical use of nanocrystals as gain media. Low-threshold blue ASE and lasing from nanocrystals is an even more challenging task. Here, we show that colloidal nanoplatelets (NPLs) with electronic structure of quantum wells can produce ASE in the red, yellow, green, and blue regions of the visible spectrum with low thresholds and high gains. In particular, for blue-emitting NPLs, the ASE threshold is 50 μJ/cm(2), lower than any reported value for nanocrystals. We then demonstrate red, yellow, green, and blue lasing using NPLs with different thicknesses. We find that the lateral size of NPLs does not show any strong effect on the Auger recombination rates and, correspondingly, on the ASE threshold or gain saturation. This observation highlights the qualitative difference of multiexciton dynamics in CdSe NPLs and other quantum-confined CdSe materials, such as quantum dots and rods. Our measurements of the gain bandwidth and gain lifetime further support the prospects of colloidal NPLs as solution-processed optical gain materials. PMID:26302368

  7. Low-threshold amplified spontaneous emission and lasing from colloidal nanocrystals of caesium lead halide perovskites.

    PubMed

    Yakunin, Sergii; Protesescu, Loredana; Krieg, Franziska; Bodnarchuk, Maryna I; Nedelcu, Georgian; Humer, Markus; De Luca, Gabriele; Fiebig, Manfred; Heiss, Wolfgang; Kovalenko, Maksym V

    2015-01-01

    Metal halide semiconductors with perovskite crystal structures have recently emerged as highly promising optoelectronic materials. Despite the recent surge of reports on microcrystalline, thin-film and bulk single-crystalline metal halides, very little is known about the photophysics of metal halides in the form of uniform, size-tunable nanocrystals. Here we report low-threshold amplified spontaneous emission and lasing from ?10?nm monodisperse colloidal nanocrystals of caesium lead halide perovskites CsPbX3 (X=Cl, Br or I, or mixed Cl/Br and Br/I systems). We find that room-temperature optical amplification can be obtained in the entire visible spectral range (440-700?nm) with low pump thresholds down to 51??J?cm(-2) and high values of modal net gain of at least 45030?cm(-1). Two kinds of lasing modes are successfully observed: whispering-gallery-mode lasing using silica microspheres as high-finesse resonators, conformally coated with CsPbX3 nanocrystals and random lasing in films of CsPbX3 nanocrystals. PMID:26290056

  8. Examination of bleederless ventilation practices for spontaneous combustion control in US coal mines

    SciTech Connect

    Organiscak, J.A.; Smith, A.C.; Diamond, W.P.; Mucho, T.P.

    1995-12-31

    The U.S. Bureau of Mines examined bleederless ventilation practices to evaluate their use as a spontaneous combustion control measure in U.S. coal mines. Results indicate that restricting airflow into mined-out areas (bleederless ventilation) is recognized worldwide as a spontaneous combustion control measure. However, ventilation practices commonly used to limit airflow to mined-out areas are not easily applicable to United States mining conditions, systems, experience and regulations. The types of bleederless ventilation systems used throughout the world and the spontaneous combustion risks associated with these systems are discussed. Primary design considerations for bleederless ventilation consist of the interaction of ventilation practices, methane drainage, ground control, seal construction and mine monitoring. Technological improvements needed for U.S. application of bleederless ventilation are also discussed.

  9. Realization of dynamic thermal emission control.

    PubMed

    Inoue, Takuya; De Zoysa, Menaka; Asano, Takashi; Noda, Susumu

    2014-10-01

    Thermal emission in the infrared range is important in various fields of research, including chemistry, medicine and atmospheric science. Recently, the possibility of controlling thermal emission based on wavelength-scale optical structures has been intensively investigated with a view towards a new generation of thermal emission devices. However, all demonstrations so far have involved the 'static' control of thermal emission; high-speed modulation of thermal emission has proved difficult to achieve because the intensity of thermal emission from an object is usually determined by its temperature, and the frequency of temperature modulation is limited to 10-100 Hz even when the thermal mass of the object is small. Here, we experimentally demonstrate the dynamic control of thermal emission via the control of emissivity (absorptivity), at a speed four orders of magnitude faster than is possible using the conventional temperature-modulation method. Our approach is based on the dynamic control of intersubband absorption in n-type quantum wells, which is enhanced by an optical resonant mode in a photonic crystal slab. The extraction of electrical carriers from the quantum wells leads to an immediate change in emissivity from 0.74 to 0.24 at the resonant wavelength while maintaining much lower emissivity at all other wavelengths. PMID:25064232

  10. Calculation of spontaneous emission from a V-type three-level atom in photonic crystals using fractional calculus

    SciTech Connect

    Huang, Chih-Hsien; Hsieh, Wen-Feng; Wu, Jing-Nuo; Cheng, Szu-Cheng; Li, Yen-Yin

    2011-07-15

    Fractional time derivative, an abstract mathematical operator of fractional calculus, is used to describe the real optical system of a V-type three-level atom embedded in a photonic crystal. A fractional kinetic equation governing the dynamics of the spontaneous emission from this optical system is obtained as a fractional Langevin equation. Solving this fractional kinetic equation by fractional calculus leads to the analytical solutions expressed in terms of fractional exponential functions. The accuracy of the obtained solutions is verified through reducing the system into the special cases whose results are consistent with the experimental observation. With accurate physical results and avoiding the complex integration for solving this optical system, we propose fractional calculus with fractional time derivative as a better mathematical method to study spontaneous emission dynamics from the optical system with non-Markovian dynamics.

  11. Controlling air emissions from incinerators

    SciTech Connect

    Foisy, M.B.; Li, R.; Chattapadhyay, A.

    1994-04-01

    Last year, EPA published final rules establishing technical standards for the use and disposal of wastewater biosolids (40 CFR, Part 503). Subpart E specifically regulates the operations of and emissions from municipal wastewater biosolids incinerators.

  12. A novel, simple and efficient dye laser with low amplified spontaneous emission background for analytical fluorescence and ionization spectroscopy

    SciTech Connect

    Matveev, Oleg I.; Omenetto, Nicolo'

    1995-04-01

    A new, simple, compact and efficient, grazing- incidence type of dye laser is suggested which has a low level of Amplified Spontaneous Emission. By using a Coumarin dye (LD 5000) pumped with a 20 mJ XeCl excimer laser, and a diffraction grating with 3000 grooves/mm, an efficiency of 11%, a spectral bandwidth of 0.6 cm{sup -1} and a tuning range from 458 to 517 nm have been obtained.

  13. Spontaneous centralization of control in a network of company ownerships.

    PubMed

    Krause, Sebastian M; Peixoto, Tiago P; Bornholdt, Stefan

    2013-01-01

    We introduce a model for the adaptive evolution of a network of company ownerships. In a recent work it has been shown that the empirical global network of corporate control is marked by a central, tightly connected "core" made of a small number of large companies which control a significant part of the global economy. Here we show how a simple, adaptive "rich get richer" dynamics can account for this characteristic, which incorporates the increased buying power of more influential companies, and in turn results in even higher control. We conclude that this kind of centralized structure can emerge without it being an explicit goal of these companies, or as a result of a well-organized strategy. PMID:24324594

  14. Spontaneous Centralization of Control in a Network of Company Ownerships

    PubMed Central

    Krause, Sebastian M.; Peixoto, Tiago P.; Bornholdt, Stefan

    2013-01-01

    We introduce a model for the adaptive evolution of a network of company ownerships. In a recent work it has been shown that the empirical global network of corporate control is marked by a central, tightly connected “core” made of a small number of large companies which control a significant part of the global economy. Here we show how a simple, adaptive “rich get richer” dynamics can account for this characteristic, which incorporates the increased buying power of more influential companies, and in turn results in even higher control. We conclude that this kind of centralized structure can emerge without it being an explicit goal of these companies, or as a result of a well-organized strategy. PMID:24324594

  15. Analysis and simulation of nonlinearity and effects of spontaneous emission in Schottky-junction-based plasmonic amplifiers.

    PubMed

    Livani, Abdolber Mallah; Kaatuzian, Hassan

    2015-07-01

    An amplifier that operates on surface plasmon polaritons has been analyzed and simulated. Nonlinearity behavior and the spontaneous emission effects of the plasmonic amplifier are investigated in this paper. A rate equations approach has been used in which parameters are derived from simulation results of the plasmonic amplifier (Silvaco/ATLAS). Details on the method of this derivation are included, which were not previously reported. Rate equations are solved numerically by MATLAB codes. These codes verify the Silvaco results. The plasmonic amplifier operates on surface plasmons with a free-space wavelength of 1550 nm. Results show that, even without the effect of spontaneous emission, gain of the plasmonic amplifier saturates in high input levels. Saturation power, which can be used for comparing nonlinearity of different amplifiers, is 2.1 dBm for this amplifier. Amplified spontaneous emission reduces the gain of the amplifiers, which is long. There is an optimum value for the length of the amplifier. For the amplifier of this work, the optimum length for the small signal condition is 265 ?m. PMID:26193159

  16. Broadening and tuning of spontaneous Raman emission in porous silicon at 1.5 μm

    NASA Astrophysics Data System (ADS)

    Sirleto, L.; Ferrara, M. A.; Rendina, I.; Jalali, B.

    2006-05-01

    In the last three years, the possibility of light generation and/or amplification in silicon, based on Raman emission, has achieved significant results. However, limitations inherent to the physics of silicon have been pointed out, too. In this letter, an approach based on Raman scattering in porous silicon is investigated. Two significant advantages with respect to silicon are proved: the broadening of spontaneous Raman emission and the tuning of the Stokes shift. Finally, we discuss about the prospect of Raman amplifier in porous silicon.

  17. Spontaneous Raman emission in porous silicon at 1.5 µm and prospects for a Raman amplifier

    NASA Astrophysics Data System (ADS)

    Sirleto, L.; Ferrara, M. A.; Jalali, B.; Rendina, I.

    2006-07-01

    In the last three years, the possibility of light generation and/or amplification in silicon, based on Raman emission, has achieved significant results. However, limitations inherent to the physics of silicon have also been pointed out. One possible option to overcome these limitations is to consider low dimensional silicon. In this paper, an approach based on Raman scattering in porous silicon is theoretically and experimentally investigated. We prove two significant advantages with respect to silicon: the broadening of the spontaneous Raman emission and the tuning of the Stokes shift. Finally, we discuss the prospect of a Raman amplifier in porous silicon.

  18. Detailed Study of the Angular Correlations in the Prompt Neutron Emission in Spontaneous Fission of 252Cf

    NASA Astrophysics Data System (ADS)

    Kopatch, Yu.; Chietera, A.; Stuttg, L.; Gnnenwein, F.; Mutterer, M.; Gagarski, A.; Guseva, I.; Chernysheva, E.; Dorvaux, O.; Hambsch, F.-J.; Hanappe, F.; Mezentseva, Z.; Telezhnikov, S.

    An experiment has been performed at IPHC Strasbourg, aimed at the detailed investigation of angular correlations in the neutron emission from spontaneous fission of 252Cf. Fission fragments were measured by the angle-sensitive double ionization chamber CODIS while neutrons were detected by a set of 60 DEMON scintillator counters. The main aim of the experiment is the observation of the correlation between the fragment spins and neutron emission anisotropy. Preliminary results, based on the Monte-Carlo simulations, as well as the preliminary analysis of the experimental data are shown.

  19. Method and composition for controlling dust emissions

    SciTech Connect

    Kalau, H.

    1990-02-14

    The invention relates in general to a method and composition for controlling the emission of dust in a variety of settings, and in particular, to a composition comprising a polyethylene oxide polymer and an anionic surfactant which can be used to enhance the coal-wetting action in a water spray and reduce the emission of coal dust in an underground mining operation.

  20. Comment on “Competition between coherent emission and broadband spontaneous emission in the quantum free electron laser” [Phys. Plasmas 20, 033106 (2013)

    SciTech Connect

    Petrillo, V.; Rossi, A. R.; Serafini, L.

    2013-12-15

    We point out that in the equation for the electron distribution evolution during Thomson/Compton or undulator radiation used in the paper: “Competition between coherent emission and broadband spontaneous emission in the quantum free electron laser” by G. R. M. Robb and R. Bonifacio [Phys. Plasmas 20, 033106 (2013)], the weight function should be the distribution of the number of emitted photons and not the photon energy distribution. Nevertheless, the considerations expressed in this comment do not alter the conclusions drawn in the paper in object.

  1. Variable emissivity laser thermal control system

    DOEpatents

    Milner, Joseph R.

    1994-01-01

    A laser thermal control system for a metal vapor laser maintains the wall mperature of the laser at a desired level by changing the effective emissivity of the water cooling jacket. This capability increases the overall efficiency of the laser.

  2. Recent trends in automotive emissions control

    SciTech Connect

    Not Available

    1990-01-01

    This book contains the proceedings on recent trends in automotive emissions control. Topics included are: The role of durability and evaluation conditions on the performance of Pt/Rh and Pd/Rh automotive catalysts, Systems approach to packaging design for automotive catalytic converters, Recent developments in electrically heated metal monoliths, and control of H{sub 2}S emissions from high-tech TWC converters.

  3. Acidic emissions control technology and costs

    SciTech Connect

    Emmel, T.E.; Waddell, J.T.; Adams, R.C. )

    1989-01-01

    This book describes acidic emissions control technology and costs. The objectives are: to identify and characterize stationary combustion and industrial sources of directly emitted acidic materials in the United States; to evaluate the feasibility of control technologies for these sources; and to estimate the costs of applying these control technologies. This book gives results of estimates, using a model plant approach, of costs for retrofitting selected acidic emission control systems to utility and industrial boilers, Claus sulfur recovery plants, catalytic cracking units, primary copper smelters, coke oven plants, primary aluminum smelters, and municipal solid waste incinerators.

  4. Systematics of spontaneous emission of intermediate mass fragments from heavy nuclei

    NASA Astrophysics Data System (ADS)

    Barwick, S. W.; Price, P. B.; Ravn, H. L.; Hourani, E.; Hussonnois, M.

    1986-07-01

    We have used polycarbonate track-recording films to confirm the rare decay mode of 226Ra by 14C emission and to set stringent upper limits on 14emission rates of 221Fr, 221Ra, and 225Ac. The 14emission rate exhibits a pronounced odd-even effect. For Ra isotopes the hindrance factor for odd-even parents relative to even-even parents is at least 10 times higher for 14C emission than for ? emission.

  5. CO2 emission of coal spontaneous combustion and its relation with coal microstructure, China.

    PubMed

    Wang, Haiyan; Chen Chen; Huang, Tao; Gao, Wei

    2015-07-01

    Coal spontaneous combustion is widely distributed all over the world. CO2 is the main greenhouse gas emitted by coal spontaneous combustion. In the present study characters of CO2 emitted by 10 typical Chinese coal spontaneous combustion and the influence of raw coal functional group on CO2 was studied. CO2 already exists under normal temperature as coal exposed in atmosphere. Under low temperature, the quality of CO2 released by coal spontaneous combustion is relatively small, but tends to increase. And corresponding with it, the oxygen consumption amount is also small. At medium temperature, the oxygen consumption increases rapidly and CO2 mass release rate begins to increase rapidly. Then, CO2 release rate increase rapidly under relatively high temperature (higher than 673 K). Over 873K, concentration of O2 is 6% and release rate of CO2 tends to be steady. It also concluded that mass ratio of CO to CO2 (CO/CO2) during coal spontaneous combustion was lowerthan 0.10 at low temperature. And then, it increased rapidly at medium temperature and reached to top at about 673 K. At 673-873 K, the ratio decreased again, and did not decrease evidently at about 873K. At temperature higher than 873K, the ratio was about 0.13. During the whole testing temperature range, CO/CO2 was not be higher than 0.26, lower than 0.2. This means that release rate of CO2 was much higher than CO during the whole process of coal spontaneous combustion. Moreover, the gas release quantity of CO2 is positively related with carbony content in raw coal. Carbonyl and carboxyl were both material basis of CO2. PMID:26364484

  6. Multi-level quantum electrodynamic calculation of spontaneous emission and small signal gain in high voltage free electron lasers

    NASA Astrophysics Data System (ADS)

    Chang, C. S.; Fluhler, H. U.

    1991-12-01

    Using the Weisskopf-Wigner technique, a self consistent quantum electrodynamic (SCQED) theory of spontaneous emission of radiation and single photon small signal gain is developed for high voltage free electron lasers (FEL). Excellent agreement is obtained simultaneously to our knowledge for the first time between the predictions and the experimental observations for lineshift, linewidth and gain. The SCQED theory predicts lineshift and broadening due to quantum mechanical effects for linear, helical and tapered undulator FELs which are not predicted by the classical/conventional FEL theories, but which have been observed 4,5,18,22,23,45,46. Excellent agreement is obtained between the SCQED theory predicted spontaneous emission spectra and the 1980?81 ACO FEL4,18, ACO Optical Klystron FEL45,46, Stanford 10.6 ?m FEL22 and Stanford 3.4 ?m FEL23 experimental spectra. This agreement is much better than the prediction from the classical/conventional FEL theory which gives errors of many tens of percent. We show that the spontaneous emission spectrum obtained from classical/conventional FEL theories is valid only in the limit of a short undulator containing a small number of periods. The small signal gain derived from the SCQED theory is shown to reduce to Colson's gain formula12,34 in the classical limit. However, the SCQED theory predicts significant reductions in the small signal gain which agree well with the ACO gain data5, and are not predicted well by Colson's formula. Due to the non-neglible finite electron state lifetime, it is discovered that a fundamental physical gain limit exists which is universal to all types of FELs within the limits of the single photon transition scheme considered (i.e. if multiphoton effects are ignored). Finally, the implications of the theoretically obtained results are discussed for practical conditions of experimental interest. It is shown that under practical experimental conditions quantum effects can be quite important in the FEL.

  7. Economic growth and carbon emission control

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenyu

    The question about whether environmental improvement is compatible with continued economic growth remains unclear and requires further study in a specific context. This study intends to provide insight on the potential for carbon emissions control in the absence of international agreement, and connect the empirical analysis with theoretical framework. The Chinese electricity generation sector is used as a case study to demonstrate the problem. Both social planner and private problems are examined to derive the conditions that define the optimal level of production and pollution. The private problem will be demonstrated under the emission regulation using an emission tax, an input tax and an abatement subsidy respectively. The social optimal emission flow is imposed into the private problem. To provide tractable analytical results, a Cobb-Douglas type production function is used to describe the joint production process of the desired output and undesired output (i.e., electricity and emissions). A modified Hamiltonian approach is employed to solve the system and the steady state solutions are examined for policy implications. The theoretical analysis suggests that the ratio of emissions to desired output (refer to 'emission factor'), is a function of productive capital and other parameters. The finding of non-constant emission factor shows that reducing emissions without further cutting back the production of desired outputs is feasible under some circumstances. Rather than an ad hoc specification, the optimal conditions derived from our theoretical framework are used to examine the relationship between desired output and emission level. Data comes from the China Statistical Yearbook and China Electric Power Yearbook and provincial information of electricity generation for the year of 1993-2003 are used to estimate the Cobb-Douglas type joint production by the full information maximum likelihood (FIML) method. The empirical analysis shed light on the optimal policies of emissions control required for achieving the social goal in a private context. The results suggest that the efficiency of abatement technology is crucial for the timing of executing the emission tax. And emission tax is preferred to an input tax, as long as the detection of emissions is not costly and abatement technology is efficient. Keywords: Economic growth, Carbon emission, Power generation, Joint production, China

  8. Self-Amplified Spontaneous Emission Free-Electron Laser with an Energy-Chirped Electron Beam and Undulator Tapering

    SciTech Connect

    Giannessi, L.; Ciocci, F.; Dattoli, G.; Del Franco, M.; Petralia, A.; Quattromini, M.; Ronsivalle, C.; Sabia, E.; Spassovsky, I.; Surrenti, V.; Bacci, A.; Rossi, A. R.; Bellaveglia, M.; Castellano, M.; Chiadroni, E.; Cultrera, L.; Filippetto, D.; Di Pirro, G.; Ferrario, M.; Ficcadenti, L.

    2011-04-08

    We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. An increase of more than 1 order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.

  9. Quantum-noise quenching in the correlated spontaneous-emission laser as a multiplicative noise process. I. A geometrical argument

    SciTech Connect

    Schleich, W.; Scully, M.O.

    1988-02-15

    We show, via simple geometrical arguments, the quantum-noise quenching in a correlated (spontaneous) emission laser (CEL). This noise quenching is a consequence of the correlation between noise sources which results in a multiplicative noise process. The steady-state distribution for the phase difference between the two electric fields in a CEL is compared and contrasted to that of a standard phase-locked laser. Noise quenching is shown to occur in the case of the CEL via an explicit solution of the Fokker-Planck equation.

  10. Apparent deviations from causality in spontaneous light emission by atomic hydrogen in the mid- and far-field regions

    NASA Astrophysics Data System (ADS)

    Debierre, Vincent; Durt, Thomas

    2016-02-01

    We investigate, in the case of the 2 P -1 S transition in atomic hydrogen, the behavior of the spontaneously emitted electromagnetic field in space-time. We focus on Glauber's wave function for the emitted photon, a quantity which we find is nonzero outside the light cone at all times after the start of the emission. We identify the uncertainty on the position of the decaying electron as a source of departure from causality in the naive sense of the term. We carry out a detailed study of the emitted electric field in the mid- and far-field regions, through analytical and numerical computations as well as asymptotic arguments.

  11. CONTROL OF AIR EMISSIONS FROM SUPERFUND SITES

    EPA Science Inventory

    This handbook is an easy-to-use tool for decision makers to evaluate emission control devices for use with Superfund remediation actions. t will assist in the selection of cost-effective control options. t is intended for use by engineers and scientists involved in preparing reme...

  12. Auditing emissions control systems prevents compliance surprises

    SciTech Connect

    Kenson, R.E.

    1996-03-01

    Operation and maintenance of air pollution control systems is a vital part of the environmental compliance plan of many manufacturing facilities. Such systems were installed to satisfy state or federal air-quality regulations, or to gain exemption from these requirements by reducing facility emissions to below regulatory thresholds. Failure to operate and maintain such control systems properly could cause a facility to exceed its permit condition, lose its desired regulatory exemption, or trigger regulatory agency reporting. Because most air emissions are invisible, it is potentially easy for a facility to overlook, inadvertently, improper or sub-optimal emissions control system operation. In these cases, even trivial problems could lead to agency enforcement actions and adverse press for the facility. A thorough, annual audit of a facility`s air pollution control system can prevent air compliance surprises.

  13. Geometry effect on spontaneous emission decay in nanosized Y2O3-Eu3+ particles

    NASA Astrophysics Data System (ADS)

    Zaitsev, S. V.; Yermolayeva, Yu. V.; Gruzintsev, A. N.; Kudrenko, E. A.; Zverkova, I. I.; Bezkrovnyi, O.; Tolmachev, A. V.; Emelchenko, G. A.

    2014-11-01

    A strong influence of shape and size on spontaneous luminescence of Eu atoms has been observed in a new class of Y2O3-Eu3+ nanoparticles including nanospheres, nanopowder and nanoplates. We demonstrate a possibility of engineering recombination time ? in nano-objects by changing the local optical environment.

  14. Optimization of BOF air emission control systems

    SciTech Connect

    Cesta, T.; Wrona, L.M.

    1995-07-01

    Fume sources from a BOF facility originate from primary and secondary emissions. Primary emissions are generated from blowing oxygen into the furnace. Secondary emissions result from hot metal transfer, desulfurization, iron ladle skimming, furnace scrap and hot metal charging, tapping and, to a lesser extent, slagging and turndown. Techniques for optimizing pollution control include: (1) improving hood capture design using advanced methods; (2) automation and sequencing of system flow control dampers with the meltshop cycle to divert spare capacity to emission sources; (3) upgrading particulate collectors to reinstate or increase original flow capacity; (4) upgrading collectors to improve cleaning efficiency; and (5) primary off-gas scrubber system simulation of combustion and gas cooling to maximize flow capacity. Several case studies are presented to illustrate these techniques.

  15. Voltage-Mediated Control of Spontaneous Bundle Oscillations in Saccular Hair Cells.

    PubMed

    Meenderink, Sebastiaan W F; Quiones, Patricia M; Bozovic, Dolores

    2015-10-28

    Hair cells of the vertebrate vestibular and auditory systems convert mechanical inputs into electrical signals that are relayed to the brain. This transduction involves mechanically gated ion channels that open following the deflection of mechanoreceptive hair bundles that reside on top of these cells. The mechano-electrical transduction includes one or more active feedback mechanisms to keep the mechanically gated ion channels in their most sensitive operating range. Coupling between the gating of the mechanosensitive ion channels and this adaptation mechanism leads to the occurrence of spontaneous limit-cycle oscillations, which indeed have been observed in vitro in hair cells from the frog sacculus and the turtle basilar papilla. We obtained simultaneous optical and electrophysiological recordings from bullfrog saccular hair cells with such spontaneously oscillating hair bundles. The spontaneous bundle oscillations allowed us to characterize several properties of mechano-electrical transduction without artificial loading the hair bundle with a mechanical stimulus probe. We show that the membrane potential of the hair cell can modulate or fully suppress innate oscillations, thus controlling the dynamic state of the bundle. We further demonstrate that this control is exerted by affecting the internal calcium concentration, which sets the resting open probability of the mechanosensitive channels. The auditory and vestibular systems could use the membrane potential of hair cells, possibly controlled via efferent innervation, to tune the dynamic states of the cells. PMID:26511238

  16. On what controls the spacing of spontaneous adiabatic shear bands in collapsing thick-walled cylinders

    NASA Astrophysics Data System (ADS)

    Lovinger, Zev; Rosenberg, Zvi; Rittel, Daniel

    2015-09-01

    Shear bands formation in collapsing thick walled cylinders occurs in a spontaneous manner. The advantage of examining spontaneous, as opposed to forced shear localization, is that it highlights the inherent susceptibility of the material to adiabatic shear banding without prescribed geometrical constraints. The Thick-Walled Cylinder technique (TWC) provides a controllable and repeatable technique to create and study multiple adiabatic shear bands. The technique, reported in the literature uses an explosive cylinder to create the driving force, collapsing the cylindrical sample. Recently, we developed an electro-magnetic set-up using a pulsed current generator to provide the collapsing force, replacing the use of explosives. Using this platform we examined the shear band evolution at different stages of formation in 7 metallic alloys, spanning a wide range of strength and failure properties. We examined the number of shear bands and spacing between them for the different materials to try and figure out what controls these parameters. The examination of the different materials enabled us to better comprehend the mechanisms which control the spatial distribution of multiple shear bands in this geometry. The results of these tests are discussed and compared to explosively driven collapsing TWC results in the literature and to existing analytical models for spontaneous adiabatic shear localization.

  17. Cavity-enhanced single photon emission from site-controlled In(Ga)As quantum dots fabricated using nanoimprint lithography

    SciTech Connect

    Tommila, J.; Hakkarainen, T. V.; Schramm, A. Guina, M.; Belykh, V. V.; Sibeldin, N. N.; Heinonen, E.

    2014-05-26

    We report on the emission dynamics of single In(Ga)As quantum dots formed in etched GaAs pits and integrated into micropillar cavities. The site-controlled quantum dots were fabricated by molecular beam epitaxy on nanoimprint lithography patterned GaAs(001) surfaces. Triggered single photon emission confirmed by photon autocorrelation measurements is demonstrated. Time-resolved photoluminescence experiments clearly show an effect of the cavity on the spontaneous emission rate of the quantum dot.

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

    PubMed

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

    2015-06-01

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

  19. Estimate of sulfur, arsenic, mercury, fluorine emissions due to spontaneous combustion of coal gangue: An important part of Chinese emission inventories.

    PubMed

    Wang, Shaobin; Luo, Kunli; Wang, Xing; Sun, Yuzhuang

    2016-02-01

    A rough estimate of the annual amount of sulfur, arsenic, mercury and fluoride emission from spontaneous combustion of coal gangue in China was determined. The weighted mean concentrations of S, As, Hg, and F in coal gangue are 1.01%, 7.98, 0.18, and 365.54 mg/kg, respectively. Amounts of S, As, Hg, and F emissions from coal gangue spontaneous combustion show approximately 1.13 Mt, and 246, 45, and 63,298 tons in 2013, respectively. The atmospheric release amount of sulfur from coal gangue is more than one tenth of this from coal combustion, and the amounts of As, Hg, and F are close to or even exceed those from coal combustion. China's coal gangue production growth from 1992 to 2013 show an obvious growth since 2002. It may indicate that Chinese coal gangue has become a potential source of air pollution, which should be included in emission inventories. PMID:26650082

  20. Systematics of spontaneous emission of intermediate mass fragments from heavy nuclei

    SciTech Connect

    Barwick, S.W.; Price, P.B.; Ravn, H.L.; Hourani, E.; Hussonnois, M.

    1986-07-01

    We have used polycarbonate track-recording films to confirm the rare decay mode of /sup 226/Ra by /sup 14/C emission and to set stringent upper limits on /sup 14/C-emission rates of /sup 221/Fr, /sup 221/Ra, and /sup 225/Ac. The /sup 14/C-emission rate exhibits a pronounced odd-even effect. For Ra isotopes the hindrance factor for odd-even parents relative to even-even parents is at least 10 times higher for /sup 14/C emission than for ..cap alpha.. emission.

  1. Amplified spontaneous emission from 2,7-bis(4-pyridyl)fluorene-doped DNA-cetyltrimethyl ammonium complex films

    NASA Astrophysics Data System (ADS)

    Zhao, Xiuhua; Li, Xing; Zhao, Yayun; Zhang, Jie; Pan, Jianguo; Zhou, Jun

    2013-10-01

    The 2,7-bis(4-pyridyl)fluorene (BPF) was synthesized via a Suzuki coupling reaction. The optical spectra properties of BPF and BPF-deoxyribonucleic acid (DNA)-cetyltrimethyl ammonium (CTMA) thin films composed of BPF, DNA, and CTMA were characterized by the measurements of UV/Vis absorption spectra and fluorescence spectra. The amplified spontaneous emission (ASE) of the BPF-DNA-CTMA films was researched experimentally by pumping of a pulse laser with a wavelength of 355 nm. The results show that the absorption peak and the fluorescence peak of BPF are located at 327 and 380 nm, respectively. The emission peak of BPF corresponds to the vibronic transitions from an excited state of S1 level to the ground state of S0 level. The ASE peak of the BPF-DNA-CTMA film is located at 384 nm, and the threshold of ASE excited energy density is 3.12 mJ.cm-2.

  2. Advanced CIDI Emission Control System Development

    SciTech Connect

    Lambert, Christine

    2006-05-31

    Ford Motor Company, with ExxonMobil and FEV, participated in the Department of Energy's (DOE) Ultra-Clean Transportation Fuels Program with the goal to develop an innovative emission control system for light-duty diesel vehicles. The focus on diesel engine emissions was a direct result of the improved volumetric fuel economy (up to 50%) and lower CO2 emissions (up to 25%) over comparable gasoline engines shown in Europe. Selective Catalytic Reduction (SCR) with aqueous urea as the NOx reductant and a Catalyzed Diesel Particulate Filter (CDPF) were chosen as the primary emission control system components. The program expected to demonstrate more than 90% durable reduction in particulate matter (PM) and NOx emissions on a light-duty truck application, based on the FTP-75 drive cycle. Very low sulfur diesel fuel (<15 ppm-wt) enabled lower PM emissions, reduced fuel economy penalty due to the emission control system and improved long-term system durability. Significant progress was made toward a durable system to meet Tier 2 Bin 5 emission standards on a 6000 lbs light-duty truck. A 40% reduction in engine-out NOx emissions was achieved with a mid-size prototype diesel engine through engine recalibration and increased exhaust gas recirculation. Use of a rapid warm-up strategy and urea SCR provided over 90% further NOx reduction while the CDPF reduced tailpipe PM to gasoline vehicle levels. Development work was conducted to separately improve urea SCR and CDPF system durability, as well as improved oxidation catalyst function. Exhaust gas NOx and ammonia sensors were also developed further. While the final emission control system did not meet Tier 2 Bin 5 NOx after 120k mi of aging on the dynamometer, it did meet the standards for HC, NMOG, and PM, and an improved SCR catalyst was shown to have potential to meet the NOx standard, assuming the DOC durability could be improved further. Models of DOC and SCR function were developed to guide the study of several key design factors for SCR systems and aid in the development of urea control strategy for maximum NOx reduction with minimum NH3 slip. A durable co-fueling system was successfully built and tested, with the help of service station nozzle and dispenser manufacturers, for simultaneous delivery of diesel fuel and aqueous urea to the vehicle. The business case for an aqueous urea infrastructure in the US for light-duty vehicles was explored.

  3. Controlling formaldehyde emissions with MBS scrubbing

    SciTech Connect

    Lundquist, P.R.

    1998-12-31

    Sodium metabisulfite (MBS)-assisted water scrubbing was selected as the most cost-effective and reliable technology for removal of dilute formaldehyde emissions from a resin manufacturing plant. Dilute formaldehyde emission streams (e.g., from process hoods, sample hoods, and other miscellaneous captured sources) required treatment in order to meet the anticipated Maximum Achievable Control Technology (MACT) standards and state air toxic requirements. Other conventional technologies (e.g., thermal oxidation, carbon adsorption, and biofiltration) were considered, but later discarded because they were cost prohibitive or technically impractical. Segregation of dilute volatile organic compound (VOC) and hazardous air pollutant (HAP) emissions from other more concentrated VOC and HAP emissions facilitated the use of technologies tailored to the characteristics of each stream type, and thereby provided significant cost savings. While past experience has shown that simple water scrubbing of dilute formaldehyde emissions would not meet generally accepted treatment performance (90+% control), removals in excess of 95% can be readily achieved with the addition of a reactant like MBS to the scrubbing liquor. MBS in solution reacts with formaldehyde absorbed by the scrubber water to form a bisulfite salt, rendering the reacted formaldehyde non-volatile. The reaction accelerates mass transfer of formaldehyde into the scrubbing liquid, thereby decreasing the size and cost of emission control equipment. Design of such systems should also consider the chemistry of the make-up water (and scrubber water) used in the process. Recirculating water scrubbers can be susceptible to carbonate scaling and other inorganic fouling experienced in similar water treatment systems (e.g., air strippers). The addition of salts to the recirculating scrubber solutions can be controlled to limit potential sulfur dioxide emissions and deposits.

  4. Controllable cavity linewidth narrowing via spontaneously generated coherence in a four level atomic system

    NASA Astrophysics Data System (ADS)

    Tian, Si-Cong; Wan, Ren-Gang; Shan, Xiao-Nan; Tong, Cun-Zhu; Qin, Li; Ning, Yong-Qiang

    2015-12-01

    A scheme for cavity linewidth narrowing in a four-level atomic system with spontaneously generated coherence is proposed. The atomic system consists of three closely spaced excited levels, which decay to one common ground level. In such a system, spontaneously generated coherence can result in the appearance of two narrow transparency windows accomplished by steep normal dispersion. When the medium is embedded in a ring cavity, two ultranarrow transmission peaks locating close to the position of the transparency windows can be obtained simultaneously. The cavity linewidth narrowing is owing to the quantum interference between the three decay channels and can be controlled by the frequency splitting of the excited levels, requiring no coupling lasers.

  5. Photoelectric charging of dust particles: Effect of spontaneous and light induced field emission of electrons

    SciTech Connect

    Sodha, M. S.; Dixit, A.

    2009-09-07

    The authors have analyzed the charging of dust particles in a plasma, taking into account the electron/ion currents to the particles, electron/ion generation and recombination, electric field emission, photoelectric emission and photoelectric field emission of electrons under the influence of light irradiation; the irradiance has been assumed to be at a level, which lets the particles retain the negative sign of the charge. Numerical results and discussion conclude the papers.

  6. Controlling the emission from semiconductor quantum dots using ultra-small tunable optical microcavities

    NASA Astrophysics Data System (ADS)

    Di, Ziyun; Jones, Helene V.; Dolan, Philip R.; Fairclough, Simon M.; Wincott, Matthew B.; Fill, Johnny; Hughes, Gareth M.; Smith, Jason M.

    2012-10-01

    We report the control of spontaneous emission from CdSe/ZnS core-shell quantum dots coupled to novel open-access optical microcavities. The cavities are fabricated by focused ion beam milling and provide mode volumes less than a cubic micrometre. The quantum dot emission spectrum, spatial modes and lifetime are all modified substantially by the presence of the cavity, and can be tuned by actively varying the cavity length. An increase in emission rate of 75% is achieved at room temperature, attributed to the Purcell effect in the bad emitter regime. We demonstrate a high degree of control over the emission from the dots, including near single-mode operation and the ability to detect strong emission from individual nanocrystals.

  7. Averaged kinetic temperature controlling algorithm: Application to spontaneous alloying in microclusters

    NASA Astrophysics Data System (ADS)

    Kobayashi, Taizo R.; Ikeda, Kensuke S.; Shimizu, Yasushi; Sawada, Shin-ichi

    2003-04-01

    A simple algorithm of velocity scaling is proposed for the isothermal simulation of nonequilibrium relaxation processes accompanied with heat generation or absorption. The algorithm controls the kinetic temperature averaged over an arbitrary time interval at an arbitrary relaxation rate and at an arbitrary velocity scaling interval. The general conditions of controlling temperature are derived analytically and criteria for stable control are established. Our algorithm is applied to simulating the effect of substrate on the "spontaneous alloying" process of metal microclusters [H. Yasuda, H. Mori, M. Komatsu, K. Takeda, and H. Fujita, J. Electron Microsc. 41, 267 (1992)]. The results are compared with the results obtained by the Langevin algorithm in which the kinetic energy of every atom is controlled by respective stochastic heat reservoir. In spite of the marked difference between the two algorithms the relaxation dynamics agree very well in quantity over a sufficient wide range of control parameters.

  8. FIRED HEATERS: NITROGEN OXIDES EMISSIONS AND CONTROLS

    EPA Science Inventory

    The report gives results of a study of nitrogen oxide (NOx) emissions from, and controls for, fired heaters. The petroleum refining and chemical manufacturing industries account for most of fired-heater energy use with an estimated 4600 fired heaters in operation, in these two in...

  9. CONTROLLING ODOROUS EMISSIONS FROM IRON FOUNDRIES

    EPA Science Inventory

    The report discusses the control of odorous emissions from iron foundries. he main process sources of odors in iron foundries are mold and core making, casting, and sand shakeout. he odors are usually caused by chemicals, which may be present as binders and other additives to the...

  10. WASTE INCINERATION AND EMISSION CONTROL TECHNOLOGIES

    EPA Science Inventory

    The paper gives results of a survey of available waste incineration and emission control technologies in the U.S., Japan, and Western Europe. Increasing concern over landfills as a waste management option and the decreasing availability of sites have focused attention on incinera...

  11. Variable emissivity laser thermal control system

    DOEpatents

    Milner, J.R.

    1994-10-25

    A laser thermal control system for a metal vapor laser maintains the wall temperature of the laser at a desired level by changing the effective emissivity of the water cooling jacket. This capability increases the overall efficiency of the laser. 8 figs.

  12. CONTROLLING EMISSIONS FROM FUEL AND WASTE COMBUSTION

    EPA Science Inventory

    Control of emissions from combustion of fuels and wastes has been a traditional focus of air pollution regulations. Significant technology developments of the '50s and '60s have been refined into reliable chemical and physical process unit operations. In the U.S., acid rain legis...

  13. Neutron emission as a function of fragment energy in the spontaneous fission of /sup 260/Md

    SciTech Connect

    Wild, J.F.; van Aarle, J.; Westmeiser, W.; Lougheed, R.W.; Hulet, E.K.; Moody, K.J.; Dougan, R.J.; Brandt, R.; Patzelt, P.

    1989-04-19

    We have made the first measurement of the number of neutrons emitted in the spontaneous fission of a nuclide in which very high fragment energies dominate the fission process. In bombardments of /sup 254/Es, we produced 28-d /sup 260/Md, which was neutron-counted in a 1-m-diam spherical tank containing a Gd-doped scintillator solution. The average number of neutrons emitted per fission is only 2.58 +- 0.11, substantially less than for other actinides. A direct correlation of neutron multiplicity with fragment excitation energy is clearly demonstrated. 3 refs., 5 figs.

  14. Prompt neutron emission from the spontaneous fission of sup 260 Md

    SciTech Connect

    Wild, J.F.; van Aarle, J.; Westmeier, W.; Lougheed, R.W.; Hulet, E.K.; Moody, K.J.; Dougan, R.J.; Koop, E.; Glaser, R.E.; Brandt, R.; Patzelt, P. Philipps University, D-3550, Marburg an der Lahn, )

    1990-02-01

    We have made the first measurement of the number of neutrons emitted from the spontaneous fission of a nuclide in which very high fragment energies dominate the fission process. In bombardments of {sup 254}Es, we produced a large sample of 28-d {sup 260}Md, which was neutron counted in a 1-m-diameter spherical tank containing a Gd-doped scintillator solution. The average number of neutrons emitted per fission is only 2.58{plus minus}0.11, substantially less than for other actinides. A linear dependence of neutron multiplicity on fragment-excitation energy is observed to the highest values of total kinetic energy.

  15. Immune responses during spontaneous control of HIV and AIDS: what is the hope for a cure?

    PubMed Central

    Saez-Cirion, A.; Jacquelin, B.; Barré-Sinoussi, F.; Müller-Trutwin, M.

    2014-01-01

    HIV research has made rapid progress and led to remarkable achievements in recent decades, the most important of which are combination antiretroviral therapies (cART). However, in the absence of a vaccine, the pandemic continues, and additional strategies are needed. The ‘towards an HIV cure’ initiative aims to eradicate HIV or at least bring about a lasting remission of infection during which the host can control viral replication in the absence of cART. Cases of spontaneous and treatment-induced control of infection offer substantial hope. Here, we describe the scientific knowledge that is lacking, and the priorities that have been established for research into a cure. We discuss in detail the immunological lessons that can be learned by studying natural human and animal models of protection and spontaneous control of viraemia or of disease progression. In particular, we describe the insights we have gained into the immune mechanisms of virus control, the impact of early virus–host interactions and why chronic inflammation, a hallmark of HIV infection, is an obstacle to a cure. Finally, we enumerate current interventions aimed towards improving the host immune response. PMID:24821922

  16. Two-dimensional imaging of spontaneous ultra-weak photon emission from the human skin: role of reactive oxygen species.

    PubMed

    Prasad, Ankush; Pospiil, Pavel

    2011-11-01

    In the human skin, reactive oxygen species (ROS) produced continuously during oxidative metabolic processes (cellular respiration, oxidative burst) are essential for various cellular processes such as defense against infection, cellular signaling and apoptosis. On the other hand, when the formation of ROS exceeds a capacity of the non-enzymatic and the enzymatic antioxidant defense system, ROS cause the damage to the human skin known to initiate premature skin aging and skin cancer. In this study, two-dimensional spontaneous ultra-weak photon emission from the human skin has been measured using a highly sensitive charged coupled device (CCD) camera. It is demonstrated here that two-dimensional ultra-weak photon emission from the human skin increases with the topical application of exogenous ROS in the following order: hydrogen peroxide (H?O?) < superoxide anion radical (O??) < hydroxyl radical (HO). We propose here that the two-dimensional ultra-weak photon emission can be used as a non-invasive tool for the spatial and temporal monitoring of oxidative stress in the human skin. PMID:22012922

  17. Spontaneous emission interference enhancement with a {mu}-negative metamaterial slab

    SciTech Connect

    Zeng Xiaodong; Xu Jingping; Yang Yaping

    2011-09-15

    The spontaneous decay and quantum interference of a V-type Zeeman atom placed near a {mu}-negative metamaterial (MNG) slab are investigated. Based on the fact that MNG slab supports only TE-polarized surface-plasmon polariton (SPP) modes, the decay rate of the dipole component parallel to the interface would be much larger than that normal to the interface, because one can couple while another decouple to TE modes. Consequently, high-level anisotropic environment is created and the two dipoles can interfere with each other strongly by sharing such SPP modes even if they are orthogonal. In our work, we analyze the influence of the parameters of the MNG slab as well as the atomic location on the interference intensity in detail. In addition, the dissipation of the slab is considered, and the quantum interference is still excellent even with large absorption.

  18. Spontaneous emission and spectral properties of radiation by relativistic electrons in a gyro-klystron and optical-klystron undulator.

    PubMed

    Prakash, Bramha; Mishra, Ganeswar; Khullar, Roma

    2016-03-01

    In this paper spontaneous emission of radiation by relativistic electrons in a gyro-klystron is studied. The scheme consists of two solenoid sections separated by a dispersive section. In the dispersive section the electrons are made non-resonant with the radiation. The dispersive section transforms a small change of the velocity into changes of the phases of the electrons. This leads to enhanced radiation due to klystron-type modulation as compared with a conventional gyrotron-type device driven by cyclotron maser interaction. It is shown that the klystron-modulated spectrum depends on the dispersive field strength, finite perpendicular velocity component and length of the solenoids but is independent of the axial magnetic field strength. A simple scheme to design a gyro-klystron is discussed. PMID:26917129

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  20. Observation of anomalously large spectral bandwidth in a high-gain self-amplified spontaneous emission free-electron laser.

    PubMed

    Andonian, G; Murokh, A; Rosenzweig, J B; Agustsson, R; Babzien, M; Ben-Zvi, I; Frigola, P; Huang, J Y; Palumbo, L; Pellegrini, C; Reiche, S; Travish, G; Vicario, C; Yakimenko, V

    2005-07-29

    Observation of ultrawide bandwidth, up to 15% full-width, high-gain operation of a self-amplified spontaneous emission free-election laser (SASE FEL) is reported. This type of lasing is obtained with a strongly chirped beam (deltaE/E approximately 1.7%) emitted from the accelerator. Because of nonlinear pulse compression during transport, a short, high current bunch with strong mismatch errors is injected into the undulator, giving high FEL gain. Start-to-end simulations reproduce key features of the measurements and provide insight into mechanisms, such as angular spread in emitted photon and electron trajectory distributions, which yield novel features in the radiation spectrum. PMID:16090882

  1. Spectral discrimination between healthy people and cold patients using spontaneous photon emission

    PubMed Central

    Yang, Meina; Pang, Jiangxiang; Liu, Junyan; Liu, Yanli; Fan, Hua; Han, Jinxiang

    2015-01-01

    In this paper, ultra-weak photon emission (UPE) was used to distinguish cold patients from healthy subjects. The UPE intensity of fingertips of two hands from healthy subjects and cold patients was measured using a two-hand UPE detecting system and a group of cut-off filters. We found a significant difference in the maximum spectral peak and photon emission ratio between the filter of 550nm and 495nm, which can be used in distinguish cold patients from healthy people. Methods and results in this work could be useful for developing a new optical diagnostic tool for early disease diagnosis in the future. PMID:25909016

  2. Advanced Emissions Control Development Program: Phase III

    SciTech Connect

    G.T. Amrhein; R.T. Bailey; W. Downs; M.J. Holmes; G.A. Kudlac; D.A. Madden

    1999-07-01

    The primary objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. The project goal is to effectively control air toxic emissions through the use of conventional flue gas clean-up equipment such as electrostatic precipitators (ESPs), fabric filters (baghouses - BH), and wet flue gas desulfurization systems (WFGD). Development work concentrated on the capture of trace metals, fine particulate, hydrogen chloride and hydrogen fluoride, with an emphasis on the control of mercury. The AECDP project is jointly funded by the US Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (OCDO), and Babcock and Wilcox, a McDermott company (B and W). This report discusses results of all three phases of the AECDP project with an emphasis on Phase III activities. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on characterization of the emissions of mercury and other air toxics and the control of these emissions for typical operating conditions of conventional flue gas clean-up equipment. Some general comments that can be made about the control of air toxics while burning a high-sulfur bituminous coal are as follows: (1) particulate control devices such as ESP's and baghouses do a good job of removing non-volatile trace metals, (2) particulate control devices (ESPs and baghouses) effectively remove the particulate-phase mercury, but the particulate-phase mercury was only a small fraction of the total for the coals tested, (3) wet scrubbing can effectively remove hydrogen chloride and hydrogen fluoride, and (4) wet scrubbers show good potential for the removal of mercury when operated under certain conditions, however, for certain applications, system enhancements can be required to achieve high removals when the scrubber is operated downstream of an ESP. Phase III (Advanced Concepts and Comparison Coals) testing was directed at the development of enhanced air toxics emissions control strategies to further reduce the emissions of mercury. Phase III results further supported the findings of previous phases and demonstrated several methods of enhancing mercury control for both unscrubbed systems and systems equipped with WFGD. Results confirmed that the addition of sorbents can be used to significantly improve the capture of mercury in downstream particulate collection equipment. In addition, Phase III testing demonstrated three methods of minimizing the potential negative impact of an ESP on downstream control of mercury in WFGD systems. These methods included decreased oxidation air flow, the addition of H{sub 2}S into the flue gas at the scrubber inlet, and the addition of EDTA into the absorber reaction tank.

  3. Spontaneous rupture of a hepatic epithelioid angiomyolipoma: damage control surgery. A case report

    PubMed Central

    OCCHIONORELLI, S.; DELLACHIESA, L.; STANO, R.; CAPPELLARI, L.; TARTARINI, D.; SEVERI, S.; PALINI, G.M.; PANSINI, G.C.; VASQUEZ, G.

    2013-01-01

    SUMMARY Background Angiomyolipoma (AML) is a rare mesenchymal tumor composed by blood vessels, adipose tissue and smooth muscle cells in variable proportions. Although it is most often diagnosed in the kidney, this tumor may originate from any part of the liver. It is often misdiagnosed as hepatocellular carcinoma (HCC) or other benign liver tumor. We describe a case of spontaneous rupture of hepatic angiomyolipoma in a young woman, with evidence of internal hemorrhage and hemoperitoneum. Case report Liver tumor rupture is a rare but real surgical emergency. In our case it has been managed according to the trauma principles of the damage control surgery. At the time of the observation, the patient presented an instable condition, so the decision-making was oriented toward a less invasive first step of liver packing instead of a more aggressive intervention such as one shot hepatic resection. Conclusion Damage control surgery with deep parenchymal sutures of the liver and pro-coagulant tissue adhesives packing abbreviates surgical time before the development of critical and irreversible physiological endpoints and permits a more confident second time surgery. This surgical management concept helps to reduce the mortality rate and the incidence of complications not only in traumatic liver damages, it works very well in spontaneous liver ruptures as well. PMID:24342160

  4. Controlling NOx emission from industrial sources

    SciTech Connect

    Srivastava, R.K.; Nueffer, W.; Grano, D.; Khan, S.; Staudt, J.E.; Jozewicz, W.

    2005-07-01

    A number of regulatory actions focused on reducing NOx emissions from stationary combustion sources have been taken in the United States in the last decade. These actions include the Acid Rain NOx regulations, the Ozone Transport Commission's NOx Budget Program, and the NOx SIP Call rulemakings. In addition to these regulations, the recent Interstate Air Quality Rulemaking proposal and other bills in the Congress are focusing on additional reductions of NOx. Industrial combustion sources accounted for about 18016 of NOx emissions in the United States in 2000 and constituted the second largest emitting source category within stationary sources, only behind electric utility sources. Based on these data, reduction of NOx emissions from industrial combustion sources is an important consideration in efforts undertaken to address the environmental concerns associated with NOx. This paper discusses primary and secondary NOx control technologies applicable to various major categories of industrial sources. The sources considered in this paper include large boilers, furnaces and fired heaters, combustion turbines, large IC engines, and cement kilns. For each source category considered in this paper, primary NOx controls are discussed first, followed by a discussion of secondary NOx controls.

  5. Dynamically correlated spontaneous-emission laser: theory and comparison with experiment

    SciTech Connect

    Bergou, J.; Orszag, M.

    1988-02-01

    A higher-order correlated-emission laser (CEL) effect is found theoretically in a Doppler-broadened medium. A full quantum-mechanical account of the CEL in the nonlinear regime shows a large reduction in the beat-signal linewidth. This behavior is confirmed by a recent experiment.

  6. Model Identification for Optimal Diesel Emissions Control

    SciTech Connect

    Stevens, Andrew J.; Sun, Yannan; Song, Xiaobo; Parker, Gordon

    2013-06-20

    In this paper we develop a model based con- troller for diesel emission reduction using system identification methods. Specifically, our method minimizes the downstream readings from a production NOx sensor while injecting a minimal amount of urea upstream. Based on the linear quadratic estimator we derive the closed form solution to a cost function that accounts for the case some of the system inputs are not controllable. Our cost function can also be tuned to trade-off between input usage and output optimization. Our approach performs better than a production controller in simulation. Our NOx conversion efficiency was 92.7% while the production controller achieved 92.4%. For NH3 conversion, our efficiency was 98.7% compared to 88.5% for the production controller.

  7. Factors controlling dimethylsulfide emission from salt marshes

    NASA Technical Reports Server (NTRS)

    Dacey, John W. H.; Wakeham, S. G.; Howes, B. L.

    1985-01-01

    The factors that control the emission of methylated gases from salt marshes are being studied. Research focusses on dimethylsulfide (DMS) formation and the mechanism of DMS and CH4 emission to the atmosphere. The approach is to consider the plants as valves regulating the emission of methylated gases to the atmosphere with the goal of developing appropriate methods for emission measurement. In the case of CH4, the sediment is the source and transport to the atmosphere occurs primarily through the internal gas spaces in the plants. The source of DMS appears to be dimethyl sulfoniopropionate (DMSP) which may play a role in osmoregulation in plant tissues. Concentrations of DMSP in leaves are typically several-fold higher than in roots and rhizomes. Even so, the large below ground biomass of this plant means that 2/3 of the DMSP in the ecosystem is below ground on the aerial basis. Upon introduction to sediment water, DMSP rapidly decomposes to DMS and acrylic acid. The solubility of a gas (its equilibrium vapor pressure) is a fundamental aspect of gas exchange kinetics. The first comprehensive study was conducted of DMS solubility in freshwater and seawater. Data suggest that the Setchenow relation holds for H at intermediate salinities collected. These data support the concept that the concentration of DMS in the atmosphere is far from equilibrium with seawater.

  8. Spontaneous and stimulated emission of ZnO/ZnMgO asymmetric double quantum wells

    NASA Astrophysics Data System (ADS)

    Su, S. C.; Lu, Y. M.; Xing, G. Z.; Wu, T.

    2010-11-01

    ZnO/Zn 0.85Mg 0.15O asymmetric double quantum wells (ADQWs) were fabricated on an m-plane Al 2O 3 substrate by plasma-assisted molecular beam epitaxy (P-MBE). The ADQW structures were confirmed by comparing the photoluminescence (PL) spectra of the ZnO/Zn 0.85Mg 0.15O MQWs and ZnO/Zn 0.85Mg 0.15O ADQWs. The exciton tunnelling properties of the ADQWs were studied by means of temperature-dependent PL spectra. The carrier tunneling through the thin barrier is conducive to stimulated emission in the wide wells (WWs) of the ADQWs. The origin of the stimulated emission is exciton-exciton scattering in the WWs of ADQWs.

  9. Influence of pump-phase fluctuations on entanglement generation using a correlated spontaneous-emission laser

    SciTech Connect

    Qamar, Shahid; Xiong Han; Zubairy, M. Suhail

    2007-06-15

    In this paper, we study the effect of phase fluctuations of the pump field upon the entanglement generation in a two-photon correlated emission laser (CEL). We consider initial vacuum and coherent state for the two-cavity modes. In both cases, we find reduction in the entanglement due to the phase fluctuations. However, our results indicate that entanglement generation is highly sensitive to phase fluctuations when we have initial coherent state in the two modes.

  10. Influence of pump-phase fluctuations on entanglement generation using a correlated spontaneous-emission laser

    NASA Astrophysics Data System (ADS)

    Qamar, Shahid; Xiong, Han; Zubairy, M. Suhail

    2007-06-01

    In this paper, we study the effect of phase fluctuations of the pump field upon the entanglement generation in a two-photon correlated emission laser (CEL). We consider initial vacuum and coherent state for the two-cavity modes. In both cases, we find reduction in the entanglement due to the phase fluctuations. However, our results indicate that entanglement generation is highly sensitive to phase fluctuations when we have initial coherent state in the two modes.

  11. The Effect of Ear Canal Pressure on Spontaneous Otoacoustic Emissions:. Comparison Between Human and Lizard Ears

    NASA Astrophysics Data System (ADS)

    van Dijk, P.; Manley, G. A.

    2009-02-01

    The center frequency, height and width of peaks in SOAE spectra depend on ear canal pressure. The width is interpreted as a measure of the inner ear source-signal-to-(e.g. thermal)-noise ratio. In humans, width increases with decreasing height. Apparently, ear canal pressure modifies the amplitude of the inner ear emission source signal. In lizards, the relation between peak width and height is not consistent. Here, middle ear transmission changes may account for many the observed amplitude effects.

  12. The research and implementation of coalfield spontaneous combustion of carbon emission WebGIS based on Silverlight and ArcGIS server

    NASA Astrophysics Data System (ADS)

    Zhu, Z.; Bi, J.; Wang, X.; Zhu, W.

    2014-02-01

    As an important sub-topic of the natural process of carbon emission data public information platform construction, coalfield spontaneous combustion of carbon emission WebGIS system has become an important study object. In connection with data features of coalfield spontaneous combustion carbon emissions (i.e. a wide range of data, which is rich and complex) and the geospatial characteristics, data is divided into attribute data and spatial data. Based on full analysis of the data, completed the detailed design of the Oracle database and stored on the Oracle database. Through Silverlight rich client technology and the expansion of WCF services, achieved the attribute data of web dynamic query, retrieval, statistical, analysis and other functions. For spatial data, we take advantage of ArcGIS Server and Silverlight-based API to invoke GIS server background published map services, GP services, Image services and other services, implemented coalfield spontaneous combustion of remote sensing image data and web map data display, data analysis, thematic map production. The study found that the Silverlight technology, based on rich client and object-oriented framework for WCF service, can efficiently constructed a WebGIS system. And then, combined with ArcGIS Silverlight API to achieve interactive query attribute data and spatial data of coalfield spontaneous emmission, can greatly improve the performance of WebGIS system. At the same time, it provided a strong guarantee for the construction of public information on China's carbon emission data.

  13. Coherent optical transition radiation and self-amplified spontaneous emission generated by chicane-compressed electron beams

    SciTech Connect

    Lumpkin, A.H.; Dejus, R.J.; Sereno, N.S.; /Argonne

    2009-02-01

    Observations of strongly enhanced optical transition radiation (OTR) following significant bunch compression of photoinjector beams by a chicane have been reported during the commissioning of the Linac Coherent Light Source (LCLS) accelerator and recently at the Advanced Photon Source (APS) linac. These localized transverse spatial features involve signal enhancements of nearly a factor of 10 and 100 in the APS case at the 150-MeV and 375-MeV OTR stations, respectively. They are consistent with a coherent process seeded by noise and may be evidence of a longitudinal space charge (LSC) microbunching instability which leads to coherent OTR (COTR) emissions. Additionally, we suggest that localized transverse structure in the previous self-amplified spontaneous emission (SASE) free-electron laser (FEL) data at APS in the visible-UV regime as reported at FEL02 may be attributed to such beam structure entering the FEL undulators and inducing the SASE startup at those structures. Separate beam structures 120 microns apart in x and 2.9 nm apart in wavelength were reported. The details of these observations and operational parameters will be presented.

  14. Spontaneous emission of Bloch oscillation radiation under the competing influences of microcavity enhancement and inhomogeneous interface degradation

    SciTech Connect

    Sokolov, V. N.; Iafrate, G. J.

    2014-02-07

    A theory for the spontaneous emission (SE) of terahertz radiation for a Bloch electron traversing a single energy miniband of a superlattice (SL) in a cavity, while undergoing elastic scattering is presented. The Bloch electron is accelerated under the influence of a superimposed external constant electric field and an internal inhomogeneous electric field, while radiating into a microcavity. The analysis of the SE accounts for both the spectral structure of nonharmonic miniband components and the Bloch oscillation degradation effects arising from elastic scattering due to SL interface roughness. The interface roughness effects are decomposed into contributions arising from independent planar and cross-correlated neighboring planar interfaces; parametric numerical estimates show that the cross-correlated contribution to the SE relaxation rate is relatively small, representing less than roughly 10% of the total relaxation rate. It is shown that the degradation effects from SL interface roughness can be more than compensated for by the enhancements derived from microcavity-based tuning of the emission frequency to the cavity density of states peak. The theoretical approach developed herein has general applicability beyond its use for elastic scattering due to interface roughness. As well, the results obtained in this analysis can be useful in the development of SL-based Bloch-oscillator terahertz devices.

  15. Automated plasma control with optical emission spectroscopy

    SciTech Connect

    Ward, P.P.

    1995-08-01

    Plasma etching and desmear processes for printed wiring board (PWB) manufacture are difficult to predict and control. Non-uniformity of most plasma processes and sensitivity to environmental changes make it difficult to maintain process stability from day to day. To assure plasma process performance, weight loss coupons or post-plasma destructive testing must be used. These techniques are not real-time methods however, and do not allow for immediate diagnosis and process correction. These tests often require scrapping some fraction of a batch to insure the integrity of the rest. Since these tests verify a successful cycle with post-plasma diagnostics, poor test results often determine that a batch is substandard and the resulting parts unusable. These tests are a costly part of the overall fabrication cost. A more efficient method of testing would allow for constant monitoring of plasma conditions and process control. Process anomalies should be detected and corrected before the parts being treated are damaged. Real time monitoring would allow for instantaneous corrections. Multiple site monitoring would allow for process mapping within one system or simultaneous monitoring of multiple systems. Optical emission spectroscopy conducted external to the plasma apparatus would allow for this sort of multifunctional analysis without perturbing the glow discharge. In this paper, optical emission spectroscopy for non-intrusive, in situ process control will be explored along with applications of this technique to for process control, failure analysis and endpoint determination in PWB manufacture.

  16. Automated plasma control with optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Ward, P. P.

    Plasma etching and desmear processes for printed wiring board (PWB) manufacture are difficult to predict and control. Non-uniformity of most plasma processes and sensitivity to environmental changes make it difficult to maintain process stability from day to day. To assure plasma process performance, weight loss coupons or post-plasma destructive testing must be used. These techniques are not real-time methods however, and do not allow for immediate diagnosis and process correction. These tests often require scrapping some fraction of a batch to insure the integrity of the rest. Since these tests verify a successful cycle with post-plasma diagnostics, poor test results often determine that a batch is substandard and the resulting parts unusable. These tests are a costly part of the overall fabrication cost. A more efficient method of testing would allow for constant monitoring of plasma conditions and process control. Process anomalies should be detected and corrected before the parts being treated are damaged. Real time monitoring would allow for instantaneous corrections. Multiple site monitoring would allow for process mapping within one system or simultaneous monitoring of multiple systems. Optical emission spectroscopy conducted external to the plasma apparatus would allow for this sort of multifunctional analysis without perturbing the glow discharge. In this paper, optical emission spectroscopy for non-intrusive, in situ process control will be explored along with applications of this technique to for process control, failure analysis and endpoint determination in PWB manufacture.

  17. Asbestos emissions from baghouse controlled sources.

    PubMed

    Harwood, C F; Oestreich, D K; Siebert, P; Stockham, J D

    1975-08-01

    There is virtually no information published on the absolute efficiency of baghouses in reducing the emmisions of fine particles of asbestos. This lack of information is unfortunate because serious occupational health problems may result from the common practice of recirculating air to conserve energy. Emission testing has been conducted at five asbestos processing plants where the emissions are controlled by baghouses. The results showed that the mass removal efficiency frequently exceeded 99.00%. Membrane filter samples of the effluent were examined by optical and electron microscope. It was observed that despite the high mass efficiency, the number of fibers emitted, which were greater than 1.5 mum in length, was about 10(4)-10(5) fibers/m3, while the number of fibers less than 1.5 mum was 10(7)-10(8) fibers/m3. The significance of the size of the fibers in terms of probably health impact is briefly discussed. PMID:1227285

  18. CONTROLLING MULTIPLE EMISSIONS FROM COAL-FIRED POWER PLANTS

    EPA Science Inventory

    The paper presents and analyzes nine existing and novel control technologies designed to achieve multipollutant emissions reductions. It provides an evaluation of multipollutant emission control technologies that are potentially available for coal-fired power plants of 25 MW capa...

  19. Polyfunctional HIV-Specific Antibody Responses Are Associated with Spontaneous HIV Control.

    PubMed

    Ackerman, Margaret E; Mikhailova, Anastassia; Brown, Eric P; Dowell, Karen G; Walker, Bruce D; Bailey-Kellogg, Chris; Suscovich, Todd J; Alter, Galit

    2016-01-01

    Elite controllers (ECs) represent a unique model of a functional cure for HIV-1 infection as these individuals develop HIV-specific immunity able to persistently suppress viremia. Because accumulating evidence suggests that HIV controllers generate antibodies with enhanced capacity to drive antibody-dependent cellular cytotoxicity (ADCC) that may contribute to viral containment, we profiled an array of extra-neutralizing antibody effector functions across HIV-infected populations with varying degrees of viral control to define the characteristics of antibodies associated with spontaneous control. While neither the overall magnitude of antibody titer nor individual effector functions were increased in ECs, a more functionally coordinated innate immune-recruiting response was observed. Specifically, ECs demonstrated polyfunctional humoral immune responses able to coordinately recruit ADCC, other NK functions, monocyte and neutrophil phagocytosis, and complement. This functionally coordinated response was associated with qualitatively superior IgG3/IgG1 responses, whereas HIV-specific IgG2/IgG4 responses, prevalent among viremic subjects, were associated with poorer overall antibody activity. Rather than linking viral control to any single activity, this study highlights the critical nature of functionally coordinated antibodies in HIV control and associates this polyfunctionality with preferential induction of potent antibody subclasses, supporting coordinated antibody activity as a goal in strategies directed at an HIV-1 functional cure. PMID:26745376

  20. Polyfunctional HIV-Specific Antibody Responses Are Associated with Spontaneous HIV Control

    PubMed Central

    Ackerman, Margaret E.; Mikhailova, Anastassia; Brown, Eric P.; Dowell, Karen G.; Walker, Bruce D.; Bailey-Kellogg, Chris; Suscovich, Todd J.; Alter, Galit

    2016-01-01

    Elite controllers (ECs) represent a unique model of a functional cure for HIV-1 infection as these individuals develop HIV-specific immunity able to persistently suppress viremia. Because accumulating evidence suggests that HIV controllers generate antibodies with enhanced capacity to drive antibody-dependent cellular cytotoxicity (ADCC) that may contribute to viral containment, we profiled an array of extra-neutralizing antibody effector functions across HIV-infected populations with varying degrees of viral control to define the characteristics of antibodies associated with spontaneous control. While neither the overall magnitude of antibody titer nor individual effector functions were increased in ECs, a more functionally coordinated innate immune–recruiting response was observed. Specifically, ECs demonstrated polyfunctional humoral immune responses able to coordinately recruit ADCC, other NK functions, monocyte and neutrophil phagocytosis, and complement. This functionally coordinated response was associated with qualitatively superior IgG3/IgG1 responses, whereas HIV-specific IgG2/IgG4 responses, prevalent among viremic subjects, were associated with poorer overall antibody activity. Rather than linking viral control to any single activity, this study highlights the critical nature of functionally coordinated antibodies in HIV control and associates this polyfunctionality with preferential induction of potent antibody subclasses, supporting coordinated antibody activity as a goal in strategies directed at an HIV-1 functional cure. PMID:26745376

  1. Metallic nanoparticles enhanced the spontaneous emission of semiconductor nanocrystals embedded in nanoimprinted photonic crystals.

    PubMed

    Reboud, V; Lévêque, G; Striccoli, M; Placido, T; Panniello, A; Curri, M L; Alducin, J A; Kehoe, T; Kehagias, N; Mecerreyes, D; Newcomb, S B; Iacopino, D; Redmond, G; Sotomayor Torres, C M

    2013-01-01

    We report on a method to enhance the light-emission efficiency of printable thin films of a polymer doped with luminescent (CdSe)ZnS nanocrystals via metallic nanoparticles and nanoimprinted photonic crystals. We experimentally show a strong fluorescence enhancement of nanocrystals by coupling exciton-plasmon with the localized surface plasmon of metallic nanoparticles. The emitted light is efficiently diffracted by photonic crystals structures directly imprinted in the nanocomposite polymer. By combining the field susceptibility technique with optical Bloch equations, we examine the interaction of the quantum and plasmonic entities at small distances. PMID:23154433

  2. Hot stuff controls for VOC emissions

    SciTech Connect

    Yewshenko, P.

    1995-12-01

    For close to three decades, American industry has paved the way and led the world in controlling volatile organic compound (VOC) emissions. As more and more systems have been installed, the history of operation for the various types of systems has broadened dramatically, spurring significant technological advances, the traditional technologies and those on the cutting edge of VOC control. With the number of technologies available, the environmental professional may have a difficult task choosing the most strategic environmental solution. The conventional, traditional or proven methodology for VOC control has been incineration. Other technologies have been used for very specific applications. In deciding the specific type of incineration system to select, the environmental professional will look at a broad spectrum of evaluation factors. These include initial system cost, operational cost, maintenance requirements, reliability factors and most importantly, the projected success of achieving 99% VOC destruction efficiency. This article provides an overview of the basic differences among incineration technologies.

  3. Micrometric spatial control of rare earth ion emission in LiNbO3: A two-dimensional multicolor array

    NASA Astrophysics Data System (ADS)

    Molina, P.; Ramrez, M. O.; Garca-Santizo, J. V.; lvarez-Garca, S.; Pazik, R.; Strek, W.; Dere?, P. J.; Baus, L. E.

    2009-08-01

    We report on the preparation and optical characterization of a two-dimensional multicolor emission arrangement obtained by embedding high refractive-index Er3+ doped CaTiO3 nanoparticles into a Nd3+ doped LiNbO3 crystal substrate prepatterned with an array of microvoids. By controlling the spatial location of the rare earth ions at the micrometer scale, we show the possibility of simultaneous spatial and spectral control of the spontaneous emission in a two-dimensional rare earth optically activated array. The results can be useful for the development of microcomposite rare earth based photonic devices, such as multicolor emission displays or pixelated color structures.

  4. Spontaneous cell polarization: Feedback control of Cdc42 GTPase breaks cellular symmetry.

    PubMed

    Martin, Sophie G

    2015-11-01

    Spontaneous polarization without spatial cues, or symmetry breaking, is a fundamental problem of spatial organization in biological systems. This question has been extensively studied using yeast models, which revealed the central role of the small GTPase switch Cdc42. Active Cdc42-GTP forms a coherent patch at the cell cortex, thought to result from amplification of a small initial stochastic inhomogeneity through positive feedback mechanisms, which induces cell polarization. Here, I review and discuss the mechanisms of Cdc42 activity self-amplification and dynamic turnover. A robust Cdc42 patch is formed through the combined effects of Cdc42 activity promoting its own activation and active Cdc42-GTP displaying reduced membrane detachment and lateral diffusion compared to inactive Cdc42-GDP. I argue the role of the actin cytoskeleton in symmetry breaking is not primarily to transport Cdc42 to the active site. Finally, negative feedback and competition mechanisms serve to control the number of polarization sites. PMID:26338468

  5. Naphthyl-functionalized oligophenyls: Photophysical properties, film morphology, and amplified spontaneous emission

    NASA Astrophysics Data System (ADS)

    Ma, Lin; Wu, Zhaoxin; Lei, Ting; Yu, Yue; Yuan, Fang; Jiao, Bo; Hou, Xun

    2016-04-01

    Herein, we reported a series of deep-blue-emitting naphthyl-functionalized oligophenyls as new organic laser active materials with tunable wavelength from 385 to 410 nm in solid state. Introduction of peripheral naphthyl into the oligophenyls enabled the great sterical dimensions due to the prominent steric hindrance but not destroyed the molecular conjugation. We assumed that it would suppress the π-π stacking efficiently, driving by intermolecular interaction, to hinder crystallization in solid films. Finally, the neat films of naphthyl-functionalized oligophenyls demonstrated amorphous state compared to the polycrystalline state of oligophenyls. Thus, naphthyl-functionalized oligophenyls displayed high emission quantum yield (22-35%) in solid state neat films. In addition, these molecules possessed large oscillator strength and radiative decay rate, as predicted by the theoretical analysis. The outstanding photophysical properties and amorphous films render naphthyl-functionalized oligophenyls a new class of optical gain media in solid state.

  6. Amplified spontaneous emission from PicoGreen dye intercalated in deoxyribonucleic acid lipid complex

    NASA Astrophysics Data System (ADS)

    Pradeep, C.; Vallabhan, C. P. G.; Radhakrishnan, P.; Nampoori, V. P. N.

    2015-12-01

    DNA as a genetic biomolecule is more commonly referred to in life sciences, genetics, and microbiology. With the development of ‘DNA photonics’, it has shown tremendous applicability as an optical and photonic material. In this letter, we introduce a novel dye PicoGreen as a lasing medium in which DNA not only acts as a host matrix but also functions as a fluorescence enhancer. A dramatic increase in the fluorescence led us to the observation of optical amplification in dye doped DNA thin films. We also indicate the possible tunability of the output emission in the green–yellow region. With the obtained results, we have enough reasons to lead to the development of DNA-based bio-lasers.

  7. Complexin controls spontaneous and evoked neurotransmitter release by regulating the timing and properties of synaptotagmin activity.

    PubMed

    Jorquera, Ramon A; Huntwork-Rodriguez, Sarah; Akbergenova, Yulia; Cho, Richard W; Littleton, J Troy

    2012-12-12

    Neurotransmitter release following synaptic vesicle (SV) fusion is the fundamental mechanism for neuronal communication. Synaptic exocytosis is a specialized form of intercellular communication that shares a common SNARE-mediated fusion mechanism with other membrane trafficking pathways. The regulation of synaptic vesicle fusion kinetics and short-term plasticity is critical for rapid encoding and transmission of signals across synapses. Several families of SNARE-binding proteins have evolved to regulate synaptic exocytosis, including Synaptotagmin (SYT) and Complexin (CPX). Here, we demonstrate that Drosophila CPX controls evoked fusion occurring via the synchronous and asynchronous pathways. cpx(-/-) mutants show increased asynchronous release, while CPX overexpression largely eliminates the asynchronous component of fusion. We also find that SYT and CPX coregulate the kinetics and Ca(2+) co-operativity of neurotransmitter release. CPX functions as a positive regulator of release in part by coupling the Ca(2+) sensor SYT to the fusion machinery and synchronizing its activity to speed fusion. In contrast, syt(-/-); cpx(-/-) double mutants completely abolish the enhanced spontaneous release observe in cpx(-/-) mutants alone, indicating CPX acts as a fusion clamp to block premature exocytosis in part by preventing inappropriate activation of the SNARE machinery by SYT. CPX levels also control the size of synaptic vesicle pools, including the immediate releasable pool and the ready releasable pool-key elements of short-term plasticity that define the ability of synapses to sustain responses during burst firing. These observations indicate CPX regulates both spontaneous and evoked fusion by modulating the timing and properties of SYT activation during the synaptic vesicle cycle. PMID:23238737

  8. Accuracy of pulse oximetry and capnography in healthy and compromised horses during spontaneous and controlled ventilation

    PubMed Central

    Koenig, Judith; McDonell, Wayne; Valverde, Alexander

    2003-01-01

    The objective of this prospective clinical study was to evaluate the accuracy of pulse oximetry and capnography in healthy and compromised horses during general anesthesia with spontaneous and controlled ventilation. Horses anesthetized in a dorsal recumbency position for arthroscopy (n = 20) or colic surgery (n = 16) were instrumented with an earlobe probe from the pulse oximeter positioned on the tip of the tongue and a sample line inserted at the Y-piece for capnography. The horses were allowed to breathe spontaneously (SV) for the first 20 min after induction, and thereafter ventilation was controlled (IPPV). Arterial blood, for blood gas analysis, was drawn 20 min after induction and 20 min after IPPV was started. Relationships between oxygen saturation as determined by pulse oximetry (SpO2), arterial oxygen saturation (SaO2), arterial carbon dioxide partial pressure (PaCO2), and end tidal carbon dioxide (P(et)CO2), several physiological variables, and the accuracy of pulse oximetry and capnography, were evaluated by BlandAltman or regression analysis. In the present study, both SpO2 and P(et)CO2 provided a relatively poor indication of SaO2 and PaCO2, respectively, in both healthy and compromised horses, especially during SV. A difference in heart rate obtained by pulse oximetry, ECG, or palpation is significantly correlated with any pulse oximeter inaccuracy. If blood gas analysis is not available, ventilation to P(et)CO2 of 35 to 45 mmHg should maintain the PaCO2 within a normal range. However, especially in compromised horses, it should never substitute blood gas analysis. PMID:12889721

  9. Electric field-modulated amplified spontaneous emission in organo-lead halide perovskite CH3NH3PbI3

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Wu, Zhaoxin; Dong, Hua; Xia, Bin; Xi, Jun; Ning, Shuya; Ma, Lin; Hou, Xun

    2015-12-01

    The electric field-modulation of the spontaneous emission (SE) and amplified spontaneous emission (ASE) in organo-lead halide perovskite CH3NH3PbI3 (aliased as MAPbI3) layer has been investigated. With the increase of the external applied electric field, the electric field-induced quenching of the SE and ASE intensity was observed, accompanying with a blue-shift of the ASE emission peaks, which can be attributed to field-induced ionization of photogenerated excitons in the MAPbI3 layer. Based on the analysis of quenching factor and the dielectric constant, we estimated an exciton binding energy 36 meV at room temperature, which will provide useful insights into the optical-electrical characteristics of MAPbI3 and pave the way for the future optoelectronic applications.

  10. PARTICULATE EMISSIONS CONTROL AND ITS IMPACTS ON THE CONTROL OF OTHER AIR POLLUTANT EMISSIONS FROM MUNICIPAL WASTE COMBUSTORS

    EPA Science Inventory

    The paper discusses particulate emissions control and its impacts on the control of other air pollutant emissions from municipal waste combustors (MWCs). Generally, particulate control is an inherent part of the systems used to limit the emissions of these air pollutants. The rel...

  11. Plasma process control with optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Ward, P. P.

    Plasma processes for cleaning, etching and desmear of electronic components and printed wiring boards (PWB) are difficult to predict and control. Non-uniformity of most plasma processes and sensitivity to environmental changes make it difficult to maintain process stability from day to day. To assure plasma process performance, weight loss coupons or post-plasma destructive testing must be used. The problem with these techniques is that they are not real-time methods and do not allow for immediate diagnosis and process correction. These methods often require scrapping some fraction of a batch to insure the integrity of the rest. Since these methods verify a successful cycle with post-plasma diagnostics, poor test results often determine that a batch is substandard and the resulting parts unusable. Both of these methods are a costly part of the overall fabrication cost. A more efficient method of testing would allow for constant monitoring of plasma conditions and process control. Process failures should be detected before the parts being treated. are damaged. Real time monitoring would allow for instantaneous corrections. Multiple site monitoring would allow for process mapping within one system or simultaneous monitoring of multiple systems. Optical emission spectroscopy conducted external to the plasma apparatus would allow for this sort of multifunctional analysis without perturbing the glow discharge. In this paper, optical emission spectroscopy for non-intrusive, in situ process control will be explored. A discussion of this technique as it applies towards process control, failure analysis and endpoint determination will be conducted. Methods for identifying process failures, progress and end of etch back and desmear processes will be discussed.

  12. Plasma process control with optical emission spectroscopy

    SciTech Connect

    Ward, P.P.

    1995-04-01

    Plasma processes for cleaning, etching and desmear of electronic components and printed wiring boards (PWB) are difficult to predict and control. Non-uniformity of most plasma processes and sensitivity to environmental changes make it difficult to maintain process stability from day to day. To assure plasma process performance, weight loss coupons or post-plasma destructive testing must be used. The problem with these techniques is that they are not real-time methods and do not allow for immediate diagnosis and process correction. These methods often require scrapping some fraction of a batch to insure the integrity of the rest. Since these methods verify a successful cycle with post-plasma diagnostics, poor test results often determine that a batch is substandard and the resulting parts unusable. Both of these methods are a costly part of the overall fabrication cost. A more efficient method of testing would allow for constant monitoring of plasma conditions and process control. Process failures should be detected before the parts being treated. are damaged. Real time monitoring would allow for instantaneous corrections. Multiple site monitoring would allow for process mapping within one system or simultaneous monitoring of multiple systems. Optical emission spectroscopy conducted external to the plasma apparatus would allow for this sort of multifunctional analysis without perturbing the glow discharge. In this paper, optical emission spectroscopy for non-intrusive, in situ process control will be explored. A discussion of this technique as it applies towards process control, failure analysis and endpoint determination will be conducted. Methods for identifying process failures, progress and end of etch back and desmear processes will be discussed.

  13. Even-odd effects in prompt emission of spontaneously fissioning even-even Pu isotopes

    NASA Astrophysics Data System (ADS)

    Tudora, A.; Hambsch, F.-J.; Giubega, G.; Visan, I.

    2015-01-01

    The available experimental Y (A, TKE) data for 236,238,240,242,244Pu(SF) together with the Zp model prescription with appropriate parameters allows the investigation of even-odd effects in fragment distributions. The size of the global even-odd effect in Y (Z) is decreasing from 244Pu(SF) to 236Pu(SF) confirming the general observation of a decrease of the even-odd effect with the fissility parameter. Charge polarizations (?Z) and root-mean squares (rms) as a function of A of 236-244Pu(SF) were obtained for the first time. In the asymmetric fission region both ?Z (A) and rms (A) exhibit oscillations with a periodicity of about 5 mass units due to the even-odd effects. The total average charge deviations < ?Z > (obtained by averaging ?Z (A) over the experimental Y (A) distribution) are of about |0.5| for all studied Pu(SF) systems. The comparison of the calculated ?Z (A) and rms (A) of 240Pu(SF) with those of 239Pu (nth, f) reported by Wahl shows an in-phase oscillation with a higher amplitude in the case of 240Pu(SF), confirming the higher even-odd effect in the case of SF. As in the previously studied cases (233,235U (nth, f), 239Pu (nth, f), 252Cf(SF)) the even-odd effects in the prompt emission of 236-244Pu(SF) are mainly due to the Z even-odd effects in fragment distributions and charge polarizations and the N even-odd effects in the average neutron separation energies from fragments < Sn >. The size of the global N even-odd effect in < Sn > is decreasing with the fissility parameter, being higher for the Pu(SF) systems compared to the previously studied systems. The prompt neutron multiplicities as a function of Z, ? (Z), exhibit sawtooth shapes with a visible staggering for asymmetric fragmentations. The size of the global Z even-odd effect in ? (Z) exhibits a decreasing trend with increasing fissility. The average prompt neutron multiplicities as a function of TKE show an increase of the even-odd effect with increasing TKE, with global effect sizes close to each other (a decrease of the effect for heavier fissioning nuclei is not observed here). The amounts of the global even-odd effect in Y (Z) and of the N even-odd effect in < Sn > of 240Pu(SF) are larger compared to 239Pu (nth, f). This fact affects the prompt emission leading to a lower Z even-odd effect in the prompt neutron multiplicity of 240Pu(SF) compared to 239Pu (nth, f).

  14. Amplified spontaneous emission in polymer-CdSe/ZnS-nanocrystal DFB structures produced by the holographic method

    NASA Astrophysics Data System (ADS)

    Smirnova, T. N.; Sakhno, O. V.; Yezhov, P. V.; Kokhtych, L. M.; Goldenberg, L. M.; Stumpe, J.

    2009-06-01

    Amplified spontaneous emission (ASE) is demonstrated in volume-distributed feedback (DFB) structures, formed by colloidal CdSe/ZnS nanocrystals and ZrO2 nanoparticles (NPs) in a polymer matrix. Periodic redistribution of the NPs in an organic matrix was carried out by holographic photopolymerization in a specially developed light-sensitive nanocomposite. The composite consists of two acrylate monomers and two types of inorganic NPs. The NPs provide for the formation of two co-phased gratingsa refractive index grating and an optical gain (losses) grating. The core-shell CdSe/ZnS nanocrystals are used as a gain medium, while ZrO2 NPs create the refractive index grating and enhance the distributed feedback. The period of the volume structure provides the feedback for lasing at the wavelength ?las of about 575 nm in the second diffraction order. In contrast to known laser systems based on volume DFB cavities, in which the different components of the formulation provide optical gain and feedback, in our case the inorganic NPs serve as an emitting material and can provide simultaneously for feedback. By pumping of DFB structures by a titanium-sapphire laser (?pump = 400 nm, pulse duration of 120 fs) normal to the sample plane, the appearance of a sharp stimulated emission along the grating-vector direction is observed. Output intensity of ASE as a function of the pump energy shows a threshold behavior and full width at half-maximum (FWHM) of the ASE spectral band decreases from 33 to 12 nm.

  15. Decoupling activation and exhaustion of B cells in spontaneous controllers of HIV infection

    PubMed Central

    Sciaranghella, Gaia; Tong, Neath; Mahan, Alison E.; Suscovich, Todd J.; Alter, Galit

    2013-01-01

    Objective To define the impact of chronic viremia and associated immune activation on B-cell exhaustion in HIV infection. Design Progressive HIV infection is marked by B-cell anergy and exhaustion coupled with dramatic hypergammaglobulinemia. Although both upregulation of CD95 and loss of CD21 have been used as markers of infection-associated B-cell dysfunction, little is known regarding the specific profiles of dysfunctional B cells and whether persistent viral replication and its associated immune activation play a central role in driving B-cell dysfunction. Methods Multiparameter flow cytometry was used to define the profile of dysfunctional B cells. The changes in the expression of CD21 and CD95 were tracked on B-cell subpopulations in patients with differential control of viral replication. Results Although the emergence of exhausted, CD21low tissue-like memory B cells followed similar patterns in both progressors and controllers, the frequency of CD21low activated memory B cells was lower in spontaneous controllers. Conclusion Our results suggest that the loss of CD21 and the upregulation of CD95 occur as separate events during the development of B-cell dysfunction. The loss of CD21 is a marker of B-cell exhaustion induced in the absence of appreciable viral replication, whereas the upregulation of CD95 is tightly linked to persistent viral replication and its associated immune activation. Thus, these dysfunctional profiles potentially represent two functionally distinct states within the B-cell compartment. PMID:23135171

  16. Spontaneous emission and absorption properties of a driven three-level system. II. The Λ and cascade models

    NASA Astrophysics Data System (ADS)

    Manka, A. S.; Doss, H. M.; Narducci, L. M.; Ru, P.; Oppo, G.-L.

    1991-04-01

    This paper is concerned with the spectral profile of spontaneously emitted radiation from Λ and cascade models of driven three-level atoms, and with the absorption spectra of a weak probe. The atoms are excited by a pair of coherent external fields that are resonant or nearly resonant with the two dipole-allowed transitions of each of these two models. The main aim of this work is to extend earlier studies of the V-model configuration of three-level atoms and to present a comprehensive survey of the emission and absorption features of these systems. In addition to a derivation of exact formulas for the spectra and explicit analytic approximations in the high-intensity limit, we provide an explanation for the existence of simultaneous stationary population inversion between pairs of atomic levels and explore the effect of Doppler broadening on the absorption profile of the weak probe. In view of the latter analysis, in particular, we conclude that gain features persist even in the presence of inhomogeneous broadening. This suggests the possibility of experimental tests in a cell rather than an atomic-beam environment.

  17. Suppression of transverse parasitic lasing and amplified spontaneous emission in Ti:sapphire amplifier by polarization-selection pump.

    PubMed

    Chu, Yuxi; Liang, Xiaoyan; Gan, Zebiao; Yu, Lianghong; Xu, Lu; Li, Ruxin; Xu, Zhizhan

    2015-07-10

    Based on the polarized-dependent absorption characteristic of Ti:S crystals, we propose a method to reduce the absorption coefficient of Ti:S by using a ?-polarized pump. For Ti:S crystals, the absorption cross section of ?-polarized pump light is approximately half that of ?-polarized pump light, which reduces the excited state density near the surface of the amplifier crystal, resulting in reduced transverse parasitic lasing and amplified spontaneous emission. The experimental results based on a diameter of 80mm Ti:S confirmed the proposed method with different index-matched cladding materials [ethanol and bromonaphthalene (BN)]. In the case of an ethanol cladding, the maximum amplified output energies for ?- and ?-polarized pumping are 20.8J and 26.8J, respectively-corresponding to 28.8% energy improvement achieved by the ?-polarized pump. In the case of a BN cladding, the maximum amplified output energies achieved by ?- and ?-polarized pumping are 40J and 44J, respectively; this result corresponds to about 10% energy improvement achieved by the ?-polarized pump. This method can be used in larger size Ti:S amplifiers. PMID:26193406

  18. Amplified and directional spontaneous emission from arbitrary composite bodies: A self-consistent treatment of Purcell effect below threshold

    NASA Astrophysics Data System (ADS)

    Jin, Weiliang; Khandekar, Chinmay; Pick, Adi; Polimeridis, Athanasios G.; Rodriguez, Alejandro W.

    2016-03-01

    We study amplified spontaneous emission (ASE) from wavelength-scale composite bodies—complicated arrangements of active and passive media—demonstrating highly directional and tunable radiation patterns, depending strongly on pump conditions, materials, and object shapes. For instance, we show that under large enough gain, PT symmetric dielectric spheres radiate mostly along either active or passive regions, depending on the gain distribution. Our predictions are based on a recently proposed fluctuating-volume-current formulation of electromagnetic radiation that can handle inhomogeneities in the dielectric and fluctuation statistics of active media, e.g., arising from the presence of nonuniform pump or material properties, which we exploit to demonstrate an approach to modeling ASE in regimes where Purcell effect (PE) has a significant impact on the gain, leading to spatial dispersion and/or changes in power requirements. The nonlinear feedback of PE on the active medium, captured by the Maxwell-Bloch equations but often ignored in linear formulations of ASE, is introduced into our linear framework by a self-consistent renormalization of the (dressed) gain parameters, requiring the solution of a large system of nonlinear equations involving many linear scattering calculations.

  19. Control emissions from marine vessel loading

    SciTech Connect

    Lawrence, G.N.; Cross, S.R.

    1994-03-01

    Regulations set by the US Coast Guard require safety measures during the loading of marine vessels connected to vapor collection systems. These regulations (which were promulgated in July 1990) immediately impacted all companies involved with the loading of benzene, due to previously enacted US Environmental Protection Agency regulations governing benzene transfer. In addition, regulations issued by the states of California, New Jersey, and Louisiana impose additional marine emission control requirements. These regulations effectively work together--the federal or state environmental rule first requires the collection of the vapors generate from vessel loading, and then the Coast Guard regulation governs the safety features that must be applied to the system. Depending on the vapor pressure of the chemical, a 10,000-barrel barge may emit over one ton of chemical to the atmosphere. Such large volumes make marine loading a prime target for the push to further reduce atmospheric pollution, and its is a good be that many more companies will be asked to look at the recovery of vapors during the loading of marine vessels. This article will aid the engineer who may be asked to evaluate the various methods of controlling emissions from vessel loading. It provides some guidance on the requirements of the Coast Guard regulations and briefly outlines some of the technologies that have been used to process the collected vapors. Some important design considerations unique to marine systems are discussed to help engineers avoid some of the potential pitfalls. Finally, some estimated costs are provided for two common types of marine vapor control systems.

  20. Coke quench car emission control system

    SciTech Connect

    Baum, J.P.

    1983-07-19

    A coke quench car emission control system includes a coke car and a filter car connected in tandem for joint movement on rails disposed adjacent a coke oven. A hood and recuperator are mounted on a third car disposed on auxiliary rails which extend longitudinally along the upper portions of both the quench car and the filter car and in end-wise alignment. The hood is adapted to be coupled to the coke oven for receiving coke during a pushing operation. The recuperation has an inlet coupled to the hood for receiving emissions and withdrawing heat therefrom. The recuperator also has an outlet which is disposed adjacent the inlet of a filter system mounted on the filter car, when the third car is positioned atop the quench car. The third car is sized so that it can be moved on the auxiliary rails from a position atop the quench car to a position atop the filter car whereby the quench car can be exposed for a quenching operation.

  1. CONTROL OF HYDROCARBON EMISSIONS FROM GASOLINE LOADING BY REFRIGERATION SYSTEMS

    EPA Science Inventory

    The report gives results of a study of the capabilities of refrigeration systems, operated at three temperatures, to control volatile organic compound (VOC) emissions from truck loading at bulk gasoline terminals. Achievable VOC emission rates were calculated for refrigeration sy...

  2. Spontaneous spiking and synaptic depression underlie noradrenergic control of feed-forward inhibition

    PubMed Central

    Kuo, Sidney P.; Trussell, Laurence O.

    2011-01-01

    Summary Inhibitory interneurons across diverse brain regions commonly exhibit spontaneous spiking activity, even in the absence of external stimuli. It is not well understood how stimulus-evoked inhibition can be distinguished from background inhibition arising from spontaneous firing. We found that noradrenaline simultaneously reduced spontaneous inhibitory inputs and enhanced evoked inhibitory currents recorded from principal neurons of the mouse dorsal cochlear nucleus (DCN). Together, these effects produced a large increase in signal-to-noise ratio for stimulus-evoked inhibition. Surprisingly, the opposing effects on background and evoked currents could both be attributed to noradrenergic silencing of spontaneous spiking in glycinergic interneurons. During spontaneous firing, glycine release was decreased due to strong short-term depression. Elimination of background spiking relieved inhibitory synapses from depression and thereby enhanced stimulus-evoked inhibition. Our findings illustrate a simple yet powerful neuromodulatory mechanism to shift the balance between background and stimulus-evoked signals. PMID:21791289

  3. Wavelength conversion of spectrum-sliced broadband amplified spontaneous emission light by hybrid four-wave mixing in highly nonlinear, dispersion-shifted fibers.

    PubMed

    Gao, Shiming; Yang, Changxi; Xiao, Xiaosheng; Tian, Yu; You, Zheng; Jin, Guofan

    2006-04-01

    We propose and demonstrate wavelength conversion of spectrum-sliced broadband amplified spontaneous emission light sources based on hybrid four-wave mixing (HFWM) in highly nonlinear, dispersion- shifted fibers (HNL-DSFs). The theory of HFWM between coherent pumps and incoherent signal is analyzed. The degenerate HFWM is demonstrated experimentally in a 1-km-long HNL-DSF, where the coherent pump light is provided by a tunable cw laser source and the incoherent signal light is spectrum-sliced from a broadband amplified spontaneous emission light source. A conversion efficiency of about -20.4 dB and a bandwidth of about 38 nm are measured. The experimental result agrees well with the theoretical analysis. PMID:19516424

  4. Wavelength conversion of spectrum-sliced broadband amplified spontaneous emission light by hybrid four-wave mixing in highly nonlinear, dispersion-shifted fibers

    NASA Astrophysics Data System (ADS)

    Gao, Shiming; Yang, Changxi; Xiao, Xiaosheng; Tian, Yu; You, Zheng; Jin, Guofan

    2006-04-01

    We propose and demonstrate wavelength conversion of spectrum-sliced broadband amplified spontaneous emission light sources based on hybrid four-wave mixing (HFWM) in highly nonlinear, dispersion- shifted fibers (HNL-DSFs). The theory of HFWM between coherent pumps and incoherent signal is analyzed. The degenerate HFWM is demonstrated experimentally in a 1-km-long HNL-DSF, where the coherent pump light is provided by a tunable cw laser source and the incoherent signal light is spectrum-sliced from a broadband amplified spontaneous emission light source. A conversion efficiency of about 20.4 dB and a bandwidth of about 38 nm are measured. The experimental result agrees well with the theoretical analysis.

  5. Quantum-noise quenching in the correlated spontaneous-emission laser as a multiplicative noise process. II. Rigorous analysis including amplitude noise

    SciTech Connect

    Schleich, W.; Scully, M.O.; von Garssen, H.

    1988-04-15

    An analytical steady-state distribution for the phase difference psi in a correlated spontaneous-emission laser (CEL) is derived based on the amplitude and phase equations of a CEL. This distribution is shown to be an excellent approximation to that obtained from a numerical simulation of the complete set of CEL equations. In particular, the effects of amplitude noise on CEL operation are considered and it is shown that fluctuations in the relative amplitude are also noise quenched.

  6. High cell density induces spontaneous bifurcations of dissolved oxygen controllers during CHO cell fermentations.

    PubMed

    Chung, John D; Chang, Conway C; Groves, James Ashley

    2003-10-20

    High cell density cultures of CHO cells growing in a bioreactor under dissolved oxygen control were found to undergo spontaneous bifurcations and a subsequent loss of stability some time into the fermentation. This loss of stability was manifested by sustained and amplified oscillations in the bioreactor dissolved oxygen concentration and in the oxygen gas flow rate to the reactor. To identify potential biological and operational causes for the phenomenon, linear stability analysis was applied in a neighborhood of the experimentally observed bifurcation point. The analysis revealed that two steady state process gains, K(P1) and K(P2), regulated k(l)a and gas phase oxygen concentration inputs, respectively, and the magnitude of K(P1) was found to determine system stability about the bifurcation point. The magnitude of K(P1), and hence the corresponding open-loop steady state gain K(OL1), scaled linearly with the bioreactor cell density, increasing with increasing cell density. These results allowed the generation of a fermentation stability diagram, which partitioned K(C)-N operating space into stable and unstable regions separated by the loci of predicted critically stable controller constants, K(C,critical), as a function of bioreactor cell density. This consistency of this operating diagram with experimentally observed changes in system stability was demonstrated. We conclude that time-dependent increases in cell density are the cause of the observed instabilities and that cell density is the critical bifurcation parameter. The results of this study should be readily applicable to the design of a more robust controller. PMID:12966579

  7. Quantum theory of two-photon correlated-spontaneous-emission lasers: Exact atom-field interaction Hamiltonian approach

    SciTech Connect

    Lu, N.; Zhu, S. )

    1989-11-15

    A quantum theory of two-photon correlated-spontaneous-emission lasers (CEL's) is developed, starting from the exact atom-field interaction Hamiltonian for cascade three-level atoms interacting with a single-mode radiation field. We consider the situation where the active atoms are prepared initially in a coherent superposition of three atomic levels and derive a master equation for the field-density operator by using a quantum theory for coherently pumped lasers. The master equation is transformed into a Fokker-Planck equation for the antinormal-ordering {ital Q} function. The drift coefficients of the Fokker-Planck equation enable us to study the steady-state operation of the two-photon CEL's analytically. We have studied both resonant two-photon CEL for which there is no threshold, and off-resonant two-photon CEL for which there exists a threshold. In both cases the initial atomic coherences provide phase locking, and squeezing in the phase quadrature of the field is found. The off-resonant two-photon CEL can build up from a vacuum when its linear gain is larger than the cavity loss (even without population inversion). Maximum squeezing is found in the no-population-inversion region with the laser intensities far below saturation in both cases, which are more than 90% for the resonant two-photon CEL and nearly 50% for the off-resonant one. Approximate steady-state {ital Q} functions are obtained for the resonant two-photon CEL and, in certain circumstances, for the off-resonant one.

  8. Incidences and range of spontaneous findings in control cynomolgus monkeys (Macaca fascicularis) used in toxicity studies.

    PubMed

    Chamanza, Ronnie; Marxfeld, Heike A; Blanco, Ana I; Naylor, Stuart W; Bradley, Alys E

    2010-06-01

    The authors performed a retrospective study to determine the incidences and range of spontaneous pathology findings in control cynomolgus monkeys. Data were collected from 570 monkeys (285 animals per sex), aged twelve to thirty-six months, from sixty regulatory studies evaluated at our laboratory between 2003 and 2009. The most common finding overall was lymphoplasmacytic infiltrates observed in the following incidence: liver (60.7%), kidneys (28.8%), heart (25.8%), salivary glands (21.2%), and stomach (12.1%). Inflammation also commonly occurred in the heart, kidneys, lungs, and stomach. The most common degenerative changes were localized fatty change in the liver, myocardial degeneration, and mineralization and pigment deposits in various tissues. Parathyroid, thyroid, and pituitary cysts; ectopic thymus in the parathyroid or thyroid gland; accessory spleen within the pancreas; and adrenohepatic fusion were among the most common congenital findings. Some incidental findings bearing similarities to drug-induced lesions were also encountered in various organs. It is hoped that the results presented here and elsewhere could form the groundwork for the creation of a reliable database of incidental pathology findings in laboratory nonhuman primates. PMID:20448082

  9. A quantum dot single-photon source with on-the-fly all-optical polarization control and timed emission

    NASA Astrophysics Data System (ADS)

    Heinze, Dirk; Breddermann, Dominik; Zrenner, Artur; Schumacher, Stefan

    2015-10-01

    Sources of single photons are key elements for applications in quantum information science. Among the different sources available, semiconductor quantum dots excel with their integrability in semiconductor on-chip solutions and the potential that photon emission can be triggered on demand. Usually, the photon is emitted from a single-exciton ground state. Polarization of the photon and time of emission are either probabilistic or pre-determined by electronic properties of the system. Here, we study the direct two-photon emission from the biexciton. The two-photon emission is enabled by a laser pulse driving the system into a virtual state inside the band gap. From this intermediate state, the single photon of interest is then spontaneously emitted. We show that emission through this higher-order transition provides a versatile approach to generate a single photon. Through the driving laser pulse, polarization state, frequency and emission time of the photon can be controlled on-the-fly.

  10. The sensitivity of the Spontaneous Selective Attention Test (SSAT): a study of schizophrenic inpatients and outpatients versus normal controls.

    PubMed

    Myles-Worsley, M; Coon, H; Byerley, W

    1998-05-25

    The Spontaneous Selective Attention Task (SSAT) is a visual word-identification task that measures the type of selective attention that occurs spontaneously when there are multiple stimuli, all potentially relevant, and insufficient time to process each of them fully. The present study was designed to examine the sensitivity of the SSAT by comparing the performance of 40 schizophrenic inpatients and 30 schizophrenic outpatients to that of 70 normal controls. The pattern of results reported previously for schizophrenic inpatients versus normals was replicated, and these findings were extended to include schizophrenic outpatients in partial symptom remission. Schizophrenic inpatients and outpatients were just as accurate in identifying words as normals, but spontaneous selective attention under conditions of predictability was abnormal in both patient groups. Furthermore, the ability of the SSAT to discriminate between schizophrenic patients and controls was confirmed. A ratio measure of spontaneous selective attention had a sensitivity of 77% and a base rate of 9% in a normal population (when a cutoff value was set to minimize false positives and false negatives). Thus, the SSAT is a sensitive measure of an attentional phenotype that may be useful in genetic studies of schizophrenia. PMID:9689717

  11. Change in intrathoracic pressure in rats with spontaneous and controlled ventilation during microgravity by parabolic flight.

    PubMed

    Gotoh, Taro Miyahara; Fujiki, Nobuhiro; Tanaka, Kunihiko; Morita, Hironobu

    2005-02-01

    We previously reported that the intrathoracic pressure (ITP) decreases and the transmural pressure of the aortic wall (TMP) increases during 4.5 s of microgravity (muG) induced by free drop. To examine the ITP response to a longer period of muG in the absence of the respiratory rate (RR) decrease, i.e., bradypnea, which occurs at the onset of muG, we measured the aortic blood pressure at the diaphragma level (AP) and ITP. We then calculated the TMP at the aortic arch level during 20 s of muG induced by parabolic flight in anesthetized rats (n = 7) with either spontaneous ventilation (SPN-V) or controlled ventilation (CONT-V). In the SPN-V group, the bradypnea was observed in all rats after the onset of the muG (RR change -13.9 +/- 2.9/min). The ITP during muG (-9.3 +/- 0.9 mmHg) was significantly lower than that during 1 G (-7.7 +/- 0.9 mmHg), and the TMP was significantly increased during muG (112 +/- 6 mmHg) compared to 1 G (103 +/- 5 mmHg). Similar changes in ITP and TMP were observed in the CONT-V group: During muG and 1G, respectively, the ITP was -8.4 +/- 0.6 mmHg and -5.9 +/- 0.7 mmHg, and the TMP was 112 +/- 6 mmHg and 101 +/- 6 mmHg, whereas no change in RR was observed because of the controlled ventilation. These results show that the ITP decreases and the TMP increases during muG, and they are not affected by a disturbance of respiratory rhythm. PMID:15796791

  12. Controlled and spontaneous magnetic field generation in a gun-driven spheromak

    NASA Astrophysics Data System (ADS)

    Woodruff, S.; Cohen, B. I.; Hooper, E. B.; Mclean, H. S.; Stallard, B. W.; Hill, D. N.; Holcomb, C. T.; Romero-Talamas, C.; Wood, R. D.; Cone, G.; Sovinec, C. R.

    2005-05-01

    In the Sustained Spheromak Physics Experiment, SSPX [E. B. Hooper, D. Pearlstein, and D. D. Ryutov, Nucl. Fusion 39, 863 (1999)], progress has been made in understanding the mechanisms that generate fields by helicity injection. SSPX injects helicity (linked magnetic flux) from 1 m diameter magnetized coaxial electrodes into a flux-conserving confinement region. Control of magnetic fluctuations (?B /B1% on the midplane edge) yields Te profiles peaked at >200eV. Trends indicate a limiting beta (?e4%-6%), and so we have been motivated to increase Te by operating with stronger magnetic field. Two new operating modes are observed to increase the magnetic field: (A) Operation with constant current and spontaneous gun voltage fluctuations. In this case, the gun is operated continuously at the threshold for ejection of plasma from the gun: stored magnetic energy of the spheromak increases gradually with ?B /B2% and large voltage fluctuations (?V1kV), giving a 50% increase in current amplification, Itor/Igun. (B) Operation with controlled current pulses. In this case, spheromak magnetic energy increases in a stepwise fashion by pulsing the gun, giving the highest magnetic fields observed for SSPX (0.7T along the geometric axis). By increasing the time between pulses, a quasisteady sustainment is produced (with periodic good confinement), comparing well with resistive magnetohydrodynamic simulations. In each case, the processes that transport the helicity into the spheromak are inductive and exhibit a scaling of field with current that exceeds those previously obtained. We use our newly found scaling to suggest how to achieve higher temperatures with a series of pulses.

  13. Controlled and Spontaneous Magnetic Field Generation in a Gun-Driven Spheromak

    SciTech Connect

    Woodruff, S; Cohen, B I; Hooper, E B; McLean, H S; Stallard, B W; Hill, D N; Holcomb, C T; Romero-Talamas, C; Wood, R D; Cone, G; Sovinec, C R

    2004-10-01

    In the Sustained Spheromak Physics Experiment, SSPX, progress has been made in understanding the mechanisms that generate fields by helicity injection. SSPX injects helicity (linked magnetic flux) from 1-m diameter magnetized coaxial electrodes into a flux-conserving confinement region. Control of magnetic fluctuations ({delta}B/B{approx}1% on the midplane edge) yields T{sub e} profiles peaked at > 200eV. Trends indicate a limiting beta ({beta}{sub e} {approx} 4-6%), and so we have been motivated to increase T{sub e} by operating with stronger magnetic field. Two new operating modes are observed to increase the magnetic field: (A) Operation with constant current and spontaneous gun voltage fluctuations. In this case, the gun is operated continuously at the threshold for ejection of plasma from the gun: stored magnetic energy of the spheromak increases gradually with {delta}B/B {approx}2% and large voltage fluctuations ({delta}V {approx} 1kV), giving a 50% increase in current amplification, I{sub tor}/I{sub gun}. (B) Operation with controlled current pulses. In this case, spheromak magnetic energy increases in a stepwise fashion by pulsing the gun, giving the highest magnetic fields observed for SSPX ({approx}0.7T along the geometric axis). By increasing the time between pulses, a quasi-steady sustainment is produced (with periodic good confinement), comparing well with resistive MHD simulations. In each case, the processes that transport the helicity into the spheromak are inductive and exhibit a scaling of field with current that exceeds those previously obtained. We use our newly found scaling to suggest how to achieve higher temperatures with a series of pulses.

  14. Controlled and spontaneous magnetic field generation in a gun-driven spheromak

    SciTech Connect

    Woodruff, S.; Cohen, B.I.; Hooper, E.B.; Mclean, H.S.; Stallard, B.W.; Hill, D.N.; Holcomb, C.T.; Romero-Talamas, C.; Wood, R.D.; Cone, G.; Sovinec, C.R.

    2005-05-15

    In the Sustained Spheromak Physics Experiment, SSPX [E. B. Hooper, D. Pearlstein, and D. D. Ryutov, Nucl. Fusion 39, 863 (1999)], progress has been made in understanding the mechanisms that generate fields by helicity injection. SSPX injects helicity (linked magnetic flux) from 1 m diameter magnetized coaxial electrodes into a flux-conserving confinement region. Control of magnetic fluctuations ({delta}B/B{approx}1% on the midplane edge) yields T{sub e} profiles peaked at >200 eV. Trends indicate a limiting beta ({beta}{sub e}{approx}4%-6%), and so we have been motivated to increase T{sub e} by operating with stronger magnetic field. Two new operating modes are observed to increase the magnetic field: (A) Operation with constant current and spontaneous gun voltage fluctuations. In this case, the gun is operated continuously at the threshold for ejection of plasma from the gun: stored magnetic energy of the spheromak increases gradually with {delta}B/B{approx}2% and large voltage fluctuations ({delta}V{approx}1 kV), giving a 50% increase in current amplification, I{sub tor}/I{sub gun}. (B) Operation with controlled current pulses. In this case, spheromak magnetic energy increases in a stepwise fashion by pulsing the gun, giving the highest magnetic fields observed for SSPX ({approx}0.7 T along the geometric axis). By increasing the time between pulses, a quasisteady sustainment is produced (with periodic good confinement), comparing well with resistive magnetohydrodynamic simulations. In each case, the processes that transport the helicity into the spheromak are inductive and exhibit a scaling of field with current that exceeds those previously obtained. We use our newly found scaling to suggest how to achieve higher temperatures with a series of pulses.

  15. Unregulated emissions from a heavy-duty diesel engine with various fuels and emission control systems.

    PubMed

    Tang, Shida; Frank, Brian P; Lanni, Thomas; Rideout, Greg; Meyer, Norman; Beregszaszy, Chris

    2007-07-15

    This study evaluated the effects of various combinations of fuels and emission control technologies on exhaust emissions from a heavy-duty diesel engine tested on an engine dynamometer. Ten fuels were studied in twenty four combinations of fuel and emission control technology configurations. Emission control systems evaluated were diesel oxidation catalyst (DOC), continuously regenerating diesel particulate filter (CRDPF), and the CRDPF coupled with an exhaust gas recirculation system (EGRT). The effects of fuel type and emission control technology on emissions of benzene, toluene, ethylbenzene, xylene (BTEX), and 1,3-butadiene, elemental carbon and organic carbon (EC/OC), carbonyls, polycyclic aromatic hydrocarbons (PAHs), and nitro-PAHs (n-PAHs) are presented in this paper. Regulated gaseous criteria pollutants of total hydrocarbons (THC), carbon monoxide (CO), oxides of nitrogen (NO(x)) and particulate matter (PM) emissions have been reported elsewhere. In general, individual unregulated emission with a CRDPF or an EGRT system is similar (at very low emission level) or much lower than that operating solely with a DOC and choosing a "best" fuel. The water emulsion PuriNO(x) fuel exhibited higher BTEX, carbonyls and PAHs emissions compared to other ultralow sulfur diesel (ULSD) fuels tested in this study while n-PAH emissions were comparable to that from other ULSD fuels. Naphthalene accounted for greater than 50% of the total PAH emissions in this study and there was no significant increase of n-PAHs with the usage of CRDPF. PMID:17711220

  16. Emissions control for ground power gas turbines

    NASA Technical Reports Server (NTRS)

    Rudney, R. A.; Priem, R. J.; Juhasz, A. J.; Anderson, D. N.; Mroz, T. S.; Mularz, E. J.

    1977-01-01

    The similarities and differences of emissions reduction technology for aircraft and ground power gas turbines is described. The capability of this technology to reduce ground power emissions to meet existing and proposed emissions standards is presented and discussed. Those areas where the developing aircraft gas turbine technology may have direct application to ground power and those areas where the needed technology may be unique to the ground power mission are pointed out. Emissions reduction technology varying from simple combustor modifications to the use of advanced combustor concepts, such as catalysis, is described and discussed.

  17. 40 CFR 266.104 - Standards to control organic emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 28 2013-07-01 2013-07-01 false Standards to control organic emissions... Standards to control organic emissions. (a) DRE standard—(1) General. Except as provided in paragraph (a)(3... and removal efficiency (DRE) of 99.99% for all organic hazardous constituents in the waste feed....

  18. 40 CFR 266.104 - Standards to control organic emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Standards to control organic emissions... Standards to control organic emissions. (a) DRE standard—(1) General. Except as provided in paragraph (a)(3... and removal efficiency (DRE) of 99.99% for all organic hazardous constituents in the waste feed....

  19. 40 CFR 266.104 - Standards to control organic emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 28 2012-07-01 2012-07-01 false Standards to control organic emissions... Standards to control organic emissions. (a) DRE standard—(1) General. Except as provided in paragraph (a)(3... and removal efficiency (DRE) of 99.99% for all organic hazardous constituents in the waste feed....

  20. 40 CFR 266.104 - Standards to control organic emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 27 2014-07-01 2014-07-01 false Standards to control organic emissions... Standards to control organic emissions. (a) DRE standard—(1) General. Except as provided in paragraph (a)(3... and removal efficiency (DRE) of 99.99% for all organic hazardous constituents in the waste feed....

  1. 40 CFR 266.104 - Standards to control organic emissions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 27 2011-07-01 2011-07-01 false Standards to control organic emissions... Standards to control organic emissions. (a) DRE standard—(1) General. Except as provided in paragraph (a)(3... and removal efficiency (DRE) of 99.99% for all organic hazardous constituents in the waste feed....

  2. 40 CFR 52.987 - Control of hydrocarbon emissions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 3 2011-07-01 2011-07-01 false Control of hydrocarbon emissions. 52.987 Section 52.987 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Louisiana § 52.987 Control of hydrocarbon emissions. (a) Notwithstanding any...

  3. 40 CFR 52.987 - Control of hydrocarbon emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Control of hydrocarbon emissions. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Louisiana § 52.987 Control of hydrocarbon... compliance date of January 1, 1980. This shall result in an estimated hydrocarbon emission reduction of...

  4. 40 CFR 52.987 - Control of hydrocarbon emissions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 3 2013-07-01 2013-07-01 false Control of hydrocarbon emissions. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Louisiana § 52.987 Control of hydrocarbon... compliance date of January 1, 1980. This shall result in an estimated hydrocarbon emission reduction of...

  5. 40 CFR 52.987 - Control of hydrocarbon emissions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 3 2014-07-01 2014-07-01 false Control of hydrocarbon emissions. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Louisiana § 52.987 Control of hydrocarbon... compliance date of January 1, 1980. This shall result in an estimated hydrocarbon emission reduction of...

  6. 40 CFR 52.987 - Control of hydrocarbon emissions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 3 2012-07-01 2012-07-01 false Control of hydrocarbon emissions. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Louisiana § 52.987 Control of hydrocarbon... compliance date of January 1, 1980. This shall result in an estimated hydrocarbon emission reduction of...

  7. Gaseous emissions from plants in controlled environments

    NASA Technical Reports Server (NTRS)

    Dubay, Denis T.

    1988-01-01

    Plant growth in a controlled ecological life support system may entail the build-up over extended time periods of phytotoxic concentrations of volatile organic compounds produced by the plants themselves. Ethylene is a prominent gaseous emission of plants, and is the focus of this report. The objective was to determine the rate of ethylene release by spring wheat, white potato, and lettuce during early, middle, and late growth stages, and during both the light and dark segments of the diurnal cycle. Plants grown hydroponically using the nutrient film technique were covered with plexiglass containers for 4 to 6 h. At intervals after enclosure, gas samples were withdrawn with a syringe and analyzed for ethylene with a gas chromatograph. Lettuce produced 10 to 100 times more ethylene than wheat or potato, with production rates ranging from 141 to 158 ng g-dry/wt/h. Wheat produced from 1.7 to 14.3 ng g-dry/wt/h, with senescent wheat producing the least amount and flowering wheat the most. Potatoes produced the least amount of ethylene, with values never exceeding 5 ng g-dry/wt/h. Lettuce and potatoes each produced ethylene at similar rates whether in dark period or light period. Ethylene sequestering of 33 to 43 percent by the plexiglass enclosures indicated that these production estimates may be low by one-third to one-half. These results suggest that concern for ethylene build-up in a contained atmosphere should be greatest when growing lettuce, and less when growing wheat or potato.

  8. Self-amplified spontaneous emission saturation at the Advanced Photon Source free-electron laser (abstract) (invited)

    NASA Astrophysics Data System (ADS)

    Moog, E. R.; Milton, S. V.; Arnold, N. D.; Benson, C.; Berg, W.; Biedron, S. G.; Borland, M.; Chae, Y.-C.; Dejus, R. J.; Den Hartog, P. K.; Deriy, B.; Erdmann, M.; Gluskin, E.; Huang, Z.; Kim, K.-J.; Lewellen, J. W.; Li, Y.; Lumpkin, A. H.; Makarov, O.; Nassiri, A.; Sajaev, V.; Soliday, R.; Tieman, B. J.; Trakhtenberg, E. M.; Travish, G.; Vasserman, I. B.; Vinokurov, N. A.; Wiemerslage, G.; Yang, B. X.

    2002-03-01

    Today, many bright photon beams in the ultraviolet and x-ray wavelength range are produced by insertion devices installed in specially designed third-generation storage rings. There is the possibility of producing photon beams that are orders of magnitude brighter than presently achieved at synchrotron sources, by using self-amplified spontaneous emission (SASE). At the Advanced Photon Source (APS), the low-energy undulator test line (LEUTL) free-electron laser (FEL) project was built to explore the SASE process in the visible through vacuum ultraviolet wavelength range. While the understanding gained in these experiments will guide future work to extend SASE FELs to shorter wavelengths, the APS FEL itself will become a continuously tunable, bright light source. Measurements of the SASE process to saturation have been made at 530 and 385 nm. A number of quantities were measured to confirm our understanding of the SASE process and to verify that saturation was reached. The intensity of the FEL light was measured versus distance along the FEL, and was found to flatten out at saturation. The statistical variation of the light intensity was found to be wide in the exponential gain region where the intensity is expected to be noisy, and narrower once saturation was reached. Absolute power measurements compare well with GINGER simulations. The FEL light spectrum at different distances along the undulator line was measured with a high-resolution spectrometer, and the many sharp spectral spikes at the beginning of the SASE process coalesce into a single peak at saturation. The energy spread in the electron beam widens markedly after saturation due to the number of electrons that transfer a significant amount of energy to the photon beam. Coherent transition radiation measurements of the electron beam as it strikes a foil provide additional confirmation of the microbunching of the electron beam. The quantities measured confirm that saturation was indeed reached. Details are given in Milton et al., Science 292, 2037 (2001) (also online at www.sciencexpress.org as 10.1126/science. 1059955, 17 May 2001), and Lewellen et al., "Present Status and Recent Results from the APS SASE FEL," to be published in the Proceedings of the 23rd International Free-Electron Laser Conference, Darmstadt, Germany, 20-24 August 2001.

  9. Temperature Dependence of Factors Controlling Isoprene Emissions

    NASA Technical Reports Server (NTRS)

    Duncan, Bryan N.; Yoshida, Yasuko; Damon, Megan R.; Douglass, Anne R.; Witte, Jacquelyn C.

    2009-01-01

    We investigated the relationship of variability in the formaldehyde (HCHO) columns measured by the Aura Ozone Monitoring Instrument (OMI) to isoprene emissions in the southeastern United States for 2005-2007. The data show that the inferred, regional-average isoprene emissions varied by about 22% during summer and are well correlated with temperature, which is known to influence emissions. Part of the correlation with temperature is likely associated with other causal factors that are temperature-dependent. We show that the variations in HCHO are convolved with the temperature dependence of surface ozone, which influences isoprene emissions, and the dependence of the HCHO column to mixed layer height as OMI's sensitivity to HCHO increases with altitude. Furthermore, we show that while there is an association of drought with the variation in HCHO, drought in the southeastern U.S. is convolved with temperature.

  10. Cooperative spontaneous emission of N atoms: Many-body eigenstates, the effect of virtual Lamb shift processes, and analogy with radiation of N classical oscillators

    SciTech Connect

    Svidzinsky, Anatoly A.; Chang, J.-T.; Scully, Marlan O.

    2010-05-15

    We consider collective emission of a single photon from a cloud of N two-level atoms (one excited, N-1 ground state). For a dense cloud the problem is reduced to finding eigenfunctions and eigenvalues of an integral equation. We discuss an exact analytical solution of this many-atom problem for a spherically symmetric atomic cloud. Some eigenstates decay much faster then the single atom decay rate, while the others undergo very slow decay. We show that virtual processes yield a small effect on the evolution of rapidly decaying states. However, they change the long time dynamics from exponential decay into a power-law behavior which can be observed experimentally. For trapped states virtual processes are much more important yielding additional decay channels which results in a slow decay of the otherwise trapped states. We also show that quantum mechanical treatment of spontaneous emission of weakly excited atomic ensemble is analogous to emission of N classical harmonic oscillators.

  11. Gas turbine combustion and emission control

    NASA Astrophysics Data System (ADS)

    Schetter, B.

    The fundamentals of combustion are discussed in the context of gaseous and liquid fuels and gas turbine fuels. Methods for reducing the emission of pollutants in gas turbines are considered. These emissions are carbon monoxide, unburnt hydrocarbons, smoke/soot, nitrogen oxides, sulphur oxides, and carbon dioxide. The focus is on nitrogen oxides. The general principles of combustor and burner design are considered: aero/can type combustors, silo combustors, and annular combustors. Premix and diffusion flames are discussed.

  12. Combustion control of organic emissions from municipal-waste combustors

    SciTech Connect

    Kilgroe, J.D.; Nelson, L.P.; Schindler, P.J.; Lanier, W.S.

    1990-01-01

    The article (1) identifies specific combustion conditions which are postulated to lead to low emission of organics--components of good combustion practice (GCP), (2) summarizes experimental correlations between GCP components and organic emissions, and (3) briefly discusses strategies for applying GCP to ensure continuous control of organic emissions. Background information on chlorinated dibenzo-p-dioxin and -furan (CDD/CDF) formation theories is also presented and additional research needed to establish the effectiveness of combustion strategies for control of municipal waste combustor (MWC) organic emissions is discussed. (NOTE: GCP is defined as combustion conditions which lead to low emissions of trace organic pollutants.) CDD/CDF are some of the most widely studied organic compounds of environmental concern. EPA has announced that it intends to propose new rules for control of MWC air emissions. Technical background studies for these rules considered the control of CDD/CDF as a surrogate for controlling emission of 'MWC organics.' These studies on the control of CDD/CDF from MWC facilities provide useful information on strategies for controlling total organic emissions from combustion sources.

  13. X-RAY NONLINEAR OPTICAL PROCESSES IN ATOMS USING A SELF-AMPLIFIED SPONTANEOUS EMISSION FREE-ELECTRON LASER

    SciTech Connect

    Rohringer, N

    2008-08-08

    X-ray free electron lasers (xFEL) will open new avenues to the virtually unexplored territory of non-linear interactions of x rays with matter. Initially xFELs will be based on the principle of self-amplified spontaneous emission (SASE). Each SASE pulse consists of a number of coherent intensity spikes of random amplitude, i.e. the process is chaotic and pulses are irreproducible. The coherence time of SASE xFELs will be a few femtoseconds for a photon energy near 1 keV. The importance of coherence properties of light in non-linear optical processes was theoretically discovered in the early 1960s. In this contribution we will illustrate the impact of field chaoticity on x-ray non-linear optical processes on neon for photon energies around 1 keV and intensities up to 10{sup 18} W/cm{sup 2}. Resonant and non-resonant processes are discussed. The first process to be addressed is the formation of a double-core hole in neon by photoionization with x rays above 1.25 keV energy. In contrast to the long-wavelength regime, non-linear optical processes in the x-ray regime are characterized in general by sequential single-photon single-electron interactions. Despite this fact, the sequential absorption of multiple x-ray photons depends on the statistical properties of the radiation field. Treating the x rays generated by a SASE FEL as fully chaotic, a quantum-mechanical analysis of inner-shell two-photon absorption is performed. By solving a system of time-dependent rate equations, we demonstrate that double-core hole formation in neon via x-ray two-photon absorption is enhanced by chaotic photon statistics. At an intensity of 10{sup 16} W/cm{sup 2}, the statistical enhancement is about 30%, much smaller than typical values in the optical regime. The second part of this presentation discusses the resonant Auger effect of atomic neon at the 1s-3p transition (at 867.1 eV). For low X-ray intensity, the excitation process 1s {yields} 3p in Neon can be treated perturbatively. The core-hole excited 1s{sup -1} 3p state is embedded in the continuum and decays via Auger-process on the timescale of approximately 5 fs. Increasing the x-ray intensity above 1.5 x 10{sup 18} W/cm{sup 2}, a peak intensity accessible with xFEL sources in the near future, x-ray induced emission from 3p back to 1s becomes possible, i.e. Rabi oscillations between these two levels can be induced. For the numerical analysis of this process, an effective two-level model, including a description of the resonant Auger decay process, is employed. The observation of x-ray-driven atomic populations dynamics in the time domain is challenging for chaotic xFEL pulses. In addition to requiring single-shot measurements, sub-femtosecond temporal resolution would be needed. The Rabi oscillations will, however, be imprinted on the kinetic energy distribution of the resonant Auger electron (see Fig. 1). Measuring the resonant Auger-electron line profile will provide information on both atomic population dynamics and x-ray pulse properties.

  14. Precipitation controls isoprene emissions from tropical ecosystems

    NASA Astrophysics Data System (ADS)

    Potosnak, M. J.; Gatti, L. V.; Guenther, A. B.; Karl, T.; Trostdorf, C. R.; Martins, W. C.; Rinne, H. J.; Yamazaki, A.

    2003-12-01

    Isoprene emissions from tropical regions account for a majority of isoprene produced globally. Current estimates of global isoprene emissions use meteorological inputs (temperature and light), ecosystem leaf area, and a time invariant, ecosystem specific emissions factor. This approach has been verified to work well for deciduous mid-latitude forests, but the approach has not been tested for tropical ecosystems where seasonality is induced by precipitation. Recent flux studies at two field stations in the tropics found strong effects of precipitation regime (dry vs. wet season) on isoprene emissions. A flux study conducted during the wet season (October 1999) at the La Selva Biological Station (10 26' N, 83 59' W, precipitation 4000 mm yr{-1}) found whole system isoprene emissions rates between 2--10 mg C m-2 h-1, while a second campaign during the dry season (April 2003) found values ranging 8--16 mg C m-2 h-1. This difference could not be explained by changes in ambient temperature or light using established emissions algorithms. The second field site near Santarm, Brazil in the Floresta Nacional do Tapajs (2 51' S, 54 58' W, precipitation 2000 mm yr{-1}), part of the Large scale Biosphere-atmosphere experiment in Amaznia (LBA), showed a similar pattern. Additionally, a 13 month isoprene concentration record at this station found a 4 fold increase during the dry season. Application of a one dimensional chemistry model predicts a similar change in isoprene source strength. A standard emission model using temperature and light could not account for these seasonal changes, but adding an empirical term that accounted for previous precipitation greatly enhanced the fit.

  15. Dynamic control of light emission faster than the lifetime limit using VO2 phase-change

    PubMed Central

    Cueff, Sbastien; Li, Dongfang; Zhou, You; Wong, Franklin J.; Kurvits, Jonathan A.; Ramanathan, Shriram; Zia, Rashid

    2015-01-01

    Modulation is a cornerstone of optical communication, and as such, governs the overall speed of data transmission. Currently, the two main strategies for modulating light are direct modulation of the excited emitter population (for example, using semiconductor lasers) and external optical modulation (for example, using MachZehnder interferometers or ring resonators). However, recent advances in nanophotonics offer an alternative approach to control spontaneous emission through modifications to the local density of optical states. Here, by leveraging the phase-change of a vanadium dioxide nanolayer, we demonstrate broadband all-optical direct modulation of 1.5??m emission from trivalent erbium ions more than three orders of magnitude faster than their excited state lifetime. This proof-of-concept demonstration shows how integration with phase-change materials can transform widespread phosphorescent materials into high-speed optical sources that can be integrated in monolithic nanoscale devices for both free-space and on-chip communication. PMID:26489436

  16. Dynamic control of light emission faster than the lifetime limit using VO2 phase-change.

    PubMed

    Cueff, Sébastien; Li, Dongfang; Zhou, You; Wong, Franklin J; Kurvits, Jonathan A; Ramanathan, Shriram; Zia, Rashid

    2015-01-01

    Modulation is a cornerstone of optical communication, and as such, governs the overall speed of data transmission. Currently, the two main strategies for modulating light are direct modulation of the excited emitter population (for example, using semiconductor lasers) and external optical modulation (for example, using Mach-Zehnder interferometers or ring resonators). However, recent advances in nanophotonics offer an alternative approach to control spontaneous emission through modifications to the local density of optical states. Here, by leveraging the phase-change of a vanadium dioxide nanolayer, we demonstrate broadband all-optical direct modulation of 1.5 μm emission from trivalent erbium ions more than three orders of magnitude faster than their excited state lifetime. This proof-of-concept demonstration shows how integration with phase-change materials can transform widespread phosphorescent materials into high-speed optical sources that can be integrated in monolithic nanoscale devices for both free-space and on-chip communication. PMID:26489436

  17. Dynamic control of light emission faster than the lifetime limit using VO2 phase-change

    NASA Astrophysics Data System (ADS)

    Cueff, Sbastien; Li, Dongfang; Zhou, You; Wong, Franklin J.; Kurvits, Jonathan A.; Ramanathan, Shriram; Zia, Rashid

    2015-10-01

    Modulation is a cornerstone of optical communication, and as such, governs the overall speed of data transmission. Currently, the two main strategies for modulating light are direct modulation of the excited emitter population (for example, using semiconductor lasers) and external optical modulation (for example, using Mach-Zehnder interferometers or ring resonators). However, recent advances in nanophotonics offer an alternative approach to control spontaneous emission through modifications to the local density of optical states. Here, by leveraging the phase-change of a vanadium dioxide nanolayer, we demonstrate broadband all-optical direct modulation of 1.5 ?m emission from trivalent erbium ions more than three orders of magnitude faster than their excited state lifetime. This proof-of-concept demonstration shows how integration with phase-change materials can transform widespread phosphorescent materials into high-speed optical sources that can be integrated in monolithic nanoscale devices for both free-space and on-chip communication.

  18. Using Transfer of Stimulus Control Technology to Promote Generalization and Spontaneity of Language

    ERIC Educational Resources Information Center

    Spencer, Trina D.; Higbee, Thomas S.

    2012-01-01

    Children with autism often use newly acquired language in restricted contexts and with limited variability. Instructional tactics that embed generalization technology have shown promise for increasing spontaneity, response variation, and the generalized use of language across settings, people, and materials. In this study, we explored the

  19. Using Transfer of Stimulus Control Technology to Promote Generalization and Spontaneity of Language

    ERIC Educational Resources Information Center

    Spencer, Trina D.; Higbee, Thomas S.

    2012-01-01

    Children with autism often use newly acquired language in restricted contexts and with limited variability. Instructional tactics that embed generalization technology have shown promise for increasing spontaneity, response variation, and the generalized use of language across settings, people, and materials. In this study, we explored the…

  20. Assessment and control of chrysotile asbestos emissions from unpaved roads

    NASA Astrophysics Data System (ADS)

    Serra, R. K.; Connor, M. A., Jr.

    1981-05-01

    The findings of field surveys and a test program to assess chrysotile asbestos emissions generated by vehicular use of unpaved roads surfaced with crushed serpentinite rock are presented. Included are discussions of Federal asbestos regulations, sampling and analysis procedures, human health effects, and various emission control techniques. The Enviromental Protection Agency believes that asbestos emissions which occur from unpaved roads and other dusty sources surfaced with serpentinite should be reduced to the greatest extent practical. Local, State, and Federal agencies responsible for road maintenance in the limited areas where asbestos emissions occur are in the best position to assess local conditions and implement the most appropriate control measures.

  1. Controlling laser emission by selecting crystal orientation

    NASA Astrophysics Data System (ADS)

    Chen, Lijuan; Han, Shujuan; Wang, Zhengping; Wang, Jiyang; Zhang, Huanjin; Yu, Haohai; Han, Shuo; Xu, Xinguang

    2013-01-01

    Based on the anisotropy of laser crystal, we demonstrate a method of adjusting laser emission by selecting crystal orientation. When the light propagating direction varies from a to c axis of Nd:LiGd(MoO4)2 crystal, emission wavelength exhibits a sensitive change of 1061 nm → 1061/1062 + 1068 nm → 1068 nm. The experimental discipline is well explained by a theoretical study of simulating on the spatial distribution of stimulated emission cross-section. This letter manifests that the laser property along non-principal-axis direction is also valuable for research and application, which breaks through the traditional custom of using laser materials processed along principal-axis.

  2. A new self-controlled case series method for analyzing spontaneous reports of adverse events after vaccination.

    PubMed

    Escolano, S; Hill, C; Tubert-Bitter, P

    2013-11-01

    In this paper, we propose new methods for analyzing cases of vaccine adverse events spontaneously reported to a surveillance database. The methods use the self-controlled case series approach, extended in several ways with parametric and nonparametric assumptions to account for the specific features of the data (large amount of underreporting and variation of reporting with time since vaccination). This work was motivated by the documented risk of intussusception after RotaShield vaccination (Wyeth-Lederle Vaccines, Radnor, Pennsylvania) and used worldwide spontaneous reports of intussusception occurring after Rotarix vaccination (GlaxoSmithKline Biologics, Research Triangle Park, North Carolina) collected between January 2004 and February 2010. The estimated risk during the 3- to 7-day period after vaccination was approximately 5 times higher after dose 1 of Rotarix than after dose 2, which is similar to published findings on the same topic. We undertook a large simulation study to evaluate the performance of the method in different scenarios, including its robustness to different sample sizes and time-dependent reporting functions. The bias was generally small, the type I error rate was correctly controlled, and the power to detect a risk ratio of 4 was satisfactory, provided that the sample size was over 100. The proposed methods are an effective way to explore and quantify vaccine safety signals from spontaneous reports. PMID:24013203

  3. Controlling quantum-dot light absorption and emission by a surface-plasmon field.

    PubMed

    Huang, Danhong; Easter, Michelle; Gumbs, Godfrey; Maradudin, A A; Lin, Shawn-Yu; Cardimona, D A; Zhang, Xiang

    2014-11-01

    The possibility for controlling both the probe-field optical gain and absorption, as well as photon conversion by a surface-plasmon-polariton near field is explored for a quantum dot located above a metal surface. In contrast to the linear response in the weak-coupling regime, the calculated spectra show an induced optical gain and a triply-split spontaneous emission peak resulting from the interference between the surface-plasmon field and the probe or self-emitted light field in such a strongly-coupled nonlinear system. Our result on the control of the mediated photon-photon interaction, very similar to the 'gate' control in an optical transistor, may be experimentally observable and applied to ultra-fast intrachip/interchip optical interconnects, improvement in the performance of fiber-optic communication networks, and developments of optical digital computers and quantum communications. PMID:25401904

  4. High amplified spontaneous emission contrast of 1011 in a Nd:glass laser based on a hybrid double chirped pulse amplification scheme

    NASA Astrophysics Data System (ADS)

    Lu, X. M.; Leng, Y. X.; Sui, Z.; Li, Y. Y.; Zhang, Z. X.; Xu, Y.; Guo, X. Y.; Liu, Y. Q.

    2014-10-01

    By using a Ti:sapphire-Nd:glass hybrid double chirped pulse amplification scheme and a pulse cleaner based on optical parametric amplification and second harmonic generation, we demonstrate high amplified spontaneous emission (ASE) contrast at 1053 nm. The optimized ASE temporal contrast of the output pulse is about 1011 at about 160 ps before the main peak with an output of 140 mJ/500 fs. And the potential of 10 J level output with high ASE contrast is demonstrated in a laser system with attenuated injection.

  5. Amplified spontaneous emission of 3-(1,1-dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole molecule embedded in various polymer matrices

    NASA Astrophysics Data System (ADS)

    Mysliwiec, Jaroslaw; Sznitko, Lech; Szukalski, Adam; Parafiniuk, Kacper; Bartkiewicz, Stanislaw; Miniewicz, Andrzej; Sahraoui, Bouchta; Rau, Ileana; Kajzar, Francois

    2012-08-01

    Results of studies on the amplified spontaneous emission (ASE) phenomenon in 3-(1,1-dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (DCNP) molecules in four different polymeric matrices are reported. We have analyzed ASE spectra coming from thin films of DCNP-matrix samples when excited by the Nd:YAG nanosecond pulsed laser doubled in frequency (? = 532 nm). We report on ASE characteristics in function of different excitation pulse energy densities evaluating ASE thresholds, exponential gain coefficients and reporting the influence of the specific matrix-dye interactions on the photo-degradation process of the dye.

  6. Angular distribution of polarized spontaneous emissions and its effect on light extraction behavior in InGaN-based light emitting diodes

    SciTech Connect

    Yuan, Gangcheng; Chen, Xinjuan; Yu, Tongjun Lu, Huimin; Chen, Zhizhong; Kang, Xiangning; Wu, Jiejun; Zhang, Guoyi

    2014-03-07

    Angular intensity distributions of differently polarized light sources in multiple quantum wells (MQWs) and their effects on extraction behavior of spontaneous emission from light emitting diode (LED) chips have been studied. Theoretical calculation based on k·p approximation, ray tracing simulation and angular electroluminescence measurement were applied in this work. It is found that the electron-hole recombination in the InGaN MQWs produces a spherical distribution of an s-polarized source and a dumbbell-shaped p-polarized source. Light rays from different polarized sources experience different extraction processes, determining the polarization degree of electro-luminescence and extraction efficiency of LEDs.

  7. Mapping the transverse coherence of the self amplified spontaneous emission of a free-electron laser with the heterodyne speckle method.

    PubMed

    Alaimo, Matteo D; Anania, Maria Pia; Artioli, Marcello; Bacci, Alberto; Bellaveglia, Marco; Ciocci, Franco; Chiadroni, Enrica; Cianchi, Alessandro; Dattoli, Giuseppe; Di Pirro, Giampierro; Ferrario, Massimo; Gatti, Giancarlo; Giannessi, Luca; Manfredda, Michele; Martucci, Roberta; Mostacci, Andrea; Paroli, Bruno; Petralia, Alberto; Petrillo, Vittoria; Pompili, Riccardo; Potenza, Marco A C; Quattormini, Marcello; Rau, Julietta; Redoglio, Daniele; Rossi, Andrea R; Serafini, Luca; Surrenti, Vincenzo; Torre, Amalia; Vaccarezza, Cristina; Villa, Fabio

    2014-12-01

    The two-dimensional single shot transverse coherence of the Self-Amplified Spontaneous Emission of the SPARC_LAB Free-Electron Laser was measured through the statistical analysis of a speckle field produced by heterodyning the radiation beam with a huge number of reference waves, scattered by a suspension of particles. In this paper we report the measurements and the evaluation of the transverse coherence along the SPARC_LAB undulator modules. The measure method was demonstrated to be precise and robust, it does not require any a priori assumptions and can be implemented over a wide range of wavelengths, from the optical radiation to the x-rays. PMID:25606931

  8. Controls over hydrocarbon emissions from boreal forest conifers

    SciTech Connect

    Lerdau, M.; Litvak, M.; Monson, R. |

    1995-06-01

    The emissions of monoterpenes and isoprene were measured from two species of conifers native to the boreal forest of Canada, jack pine, Pinus rigida, and black spruce, Picea Mariana. We examined the effects of phenology and needle age on the emissions of these compounds, and the variations in tissue concentrations of monoterpenes. We measured photosynthetic carbon uptake and hydrocarbon emissions at two sites in northern Saskatchewan under controlled light, temperatures, and CO{sub 2} concentrations, and analyzed carbon uptake rates using an infra-red gas analyzer and hydrocarbon emissions using a solid sorbent/thermal desorption system coupled to a gas chromatograph with a mass spectrometer. Our data indicate a strong effect of temperature and seasonality on emissions but only small effects of site conditions. These results suggest that regional models of hydrocarbon emissions from boreal forests should focus on temperature and phenology as the most important controlling variables.

  9. Sulfur oxide adsorbents and emissions control

    DOEpatents

    Li, Liyu (Richland, WA); King, David L. (Richland, WA)

    2006-12-26

    High capacity sulfur oxide absorbents utilizing manganese-based octahedral molecular sieve (Mn--OMS) materials are disclosed. An emissions reduction system for a combustion exhaust includes a scrubber 24 containing these high capacity sulfur oxide absorbents located upstream from a NOX filter 26 or particulate trap.

  10. Emission control devices, fuel additive, and fuel composition changes.

    PubMed Central

    Piver, W T

    1977-01-01

    Emission control devices are installed to meet the exhaust standards of the Clean Air Act for carbon monoxide and hydrocarbons, and it is necessary to know, from a public health point of view, how exhaust emissions may be affected by changes in fuel additives and fuel composition. Since these topics are concerned with developing technologies, the available literature on exhaust emission characteristics and the limited information on health effects, is reviewed. PMID:71235

  11. Alternative control technology document for bakery oven emissions. Final report

    SciTech Connect

    Sanford, C.W.

    1992-12-01

    The document was produced in response to a request by the baking industry for Federal guidance to assist in providing a more uniform information base for State decision-making with regard to control of bakery oven emissions. The information in the document pertains to bakeries that produce yeast-leavened bread, rolls, buns, and similar products but not crackers, sweet goods, or baked foodstuffs that are not yeast leavened. Information on the baking processes, equipment, operating parameters, potential emissions from baking, and potential emission control options are presented. Catalytic and regenerative oxidation are identified as the most appropriate existing control technologies applicable to VOC emissions from bakery ovens. Cost analyses for catalytic and regenerative oxidation are included. A predictive formula for use in estimating oven emissions has been derived from source tests done in junction with the development of the document. Its use and applicability are described.

  12. Neurophysiology of spontaneous facial expressions: I. Motor control of the upper and lower face is behaviorally independent in adults.

    PubMed

    Ross, Elliott D; Gupta, Smita S; Adnan, Asif M; Holden, Thomas L; Havlicek, Joseph; Radhakrishnan, Sridhar

    2016-03-01

    Facial expressions are described traditionally as monolithic entities. However, humans have the capacity to produce facial blends, in which the upper and lower face simultaneously display different emotional expressions. This, in turn, has led to the Component Theory of facial expressions. Recent neuroanatomical studies in monkeys have demonstrated that there are separate cortical motor areas for controlling the upper and lower face that, presumably, also occur in humans. The lower face is represented on the posterior ventrolateral surface of the frontal lobes in the primary motor and premotor cortices and the upper face is represented on the medial surface of the posterior frontal lobes in the supplementary motor and anterior cingulate cortices. Our laboratory has been engaged in a series of studies exploring the perception and production of facial blends. Using high-speed videography, we began measuring the temporal aspects of facial expressions to develop a more complete understanding of the neurophysiology underlying facial expressions and facial blends. The goal of the research presented here was to determine if spontaneous facial expressions in adults are predominantly monolithic or exhibit independent motor control of the upper and lower face. We found that spontaneous facial expressions are very complex and that the motor control of the upper and lower face is overwhelmingly independent, thus robustly supporting the Component Theory of facial expressions. Seemingly monolithic expressions, be they full facial or facial blends, are most likely the result of a timing coincident rather than a synchronous coordination between the ventrolateral and medial cortical motor areas responsible for controlling the lower and upper face, respectively. In addition, we found evidence that the right and left face may also exhibit independent motor control, thus supporting the concept that spontaneous facial expressions are organized predominantly across the horizontal facial axis and secondarily across the vertical axis. PMID:26854960

  13. Integrated emissions control system for residential CWS furnace

    SciTech Connect

    Balsavich, J.C. Jr.

    1991-11-01

    To meet the emission goals set by the Pittsburgh Energy Technology Center (PETC), Tecogen Inc. is developing a novel, integrated emission control system to control NO{sub x}, SO{sub 2}, and particulate emissions. At the heart of this system is a unique emissions control reactor for the control of SO{sub 2}. This reactor provides high sorbent particle residence time within the reactor while doing so in a very compact geometry. In addition to controlling SO{sub 2} emissions, the reactor provides a means of extracting a substantial amount of the particulates present in the combustion gases. Final cleanup of any fine particulates exiting the reactor, including respirable-sized particulates, is completed with the use of high efficiency bag filters. With SO{sub 2} and particulate emissions being dealt with by an emissions control reactor and bag filters, the control of NO{sub x} emissions needs to be addressed. Under a previous contract with PETC (contract No. AC22-87PC79650), Tecogen developed a residential-scale Coal Water Slurry (CWS) combustor. This combustor makes use of centrifugal forces, set up by a predominantly tangential flow field, to separate and confine larger unburned coal particles in the furnace upper chamber. Various partitions are used to retard the axial, downward flow of these particles, and thus maximize their residence time in the hottest section of the combustor. By operating this combustor under staged conditions, the local stoichiometry in the primary zone can be controlled in such a manner as to minimize NO{sub x} emissions.

  14. On-demand optogenetic control of spontaneous seizures in temporal lobe epilepsy

    PubMed Central

    Krook-Magnuson, Esther; Armstrong, Caren; Oijala, Mikko; Soltesz, Ivan

    2013-01-01

    Temporal lobe epilepsy is the most common type of epilepsy in adults, is often medically refractory, and due to broad actions and long-time scales, current systemic treatments have major negative side-effects. However, temporal lobe seizures tend to arise from discrete regions before overt clinical behaviour, making temporally and spatially specific treatment theoretically possible. Here we report the arrest of spontaneous seizures using a real-time, closed-loop, response system and in vivo optogenetics in a mouse model of temporal lobe epilepsy. Either optogenetic inhibition of excitatory principal cells, or activation of a subpopulation of GABAergic cells representing <5% of hippocampal neurons, stops seizures rapidly upon light application. These results demonstrate that spontaneous temporal lobe seizures can be detected and terminated by modulating specific cell populations in a spatially restricted manner. A clinical approach built on these principles may overcome many of the side-effects of currently available treatment options. PMID:23340416

  15. EVALUATION OF MAINTENANCE FOR FUGITIVE VOC EMISSIONS CONTROL

    EPA Science Inventory

    The U.S. EPA Office of Air Quality Planning and Standards (OAQPS) has the responsibility for formulating regulations for the control of fugitive emissions of volatile organic compounds (VOC). 'Fugitive emissions' generally refers to the diffuse release of vaporized hydrocarbon or...

  16. IRON AND STEEL PLANT OPEN SOURCE FUGITIVE EMISSION CONTROL EVALUATION

    EPA Science Inventory

    The report gives results of measurements of the control efficiency of various techniques used to mitigate emissions from open dust sources in the iron and steel industry. Of estimated emissions of 88,800 tons/year suspended particulate in 1978 (based on a 10-plant survey), 70, 13...

  17. EVALUATION OF EMISSIONS AND CONTROL TECHNOLOGY FOR INDUSTRIAL STOKER BOILERS

    EPA Science Inventory

    The report gives results of a three-phase program to evaluate emissions and control technology for industrial stoker boilers. In Phase I, emission characteristics were determined for a variety of coals fired in a 200-kW stoker boiler. It was observed that significant amounts of s...

  18. Advanced Combustion and Emission Control Technical Team Roadmap

    SciTech Connect

    2013-06-01

    The Advanced Combustion and Emission Control (ACEC) Technical Team is focused on removing technical barriers to the commercialization of advanced, high-efficiency, emission-compliant internal combustion (IC) engines for light-duty vehicle powertrains (i.e., passenger car, minivan, SUV, and pickup trucks).

  19. CONTROL OF MOTOR VEHICLE EMISSIONS - THE U.S. EXPERIENCE

    EPA Science Inventory

    An historical overview of the U.S. experience with controlling emissions from highway motor vehicles is presented. he evolution of new motor vehicle emissions certification practice, end-of-assembly-line inspection, in-use surveillance and recall, inspection and maintenance, and ...

  20. PERFORMANCE OF EMISSIONS CONTROL SYSTEMS ON MUNICIPAL WASTE COMBUSTORS

    EPA Science Inventory

    The paper reports results of several EPA-supported field evaluations of data on gaseous pollutant emissions from modern municipal waste combustors/incinerators and emissions control by flue gas cleaning systems. The results are presented in terms of acid gas (HCl and SO2), trace ...

  1. Emission control technology for diesel trucks (draft). Report to Congress

    SciTech Connect

    Not Available

    1993-10-01

    The report provides an overview of the various technologies being developed to meet the exhaust emission standards for diesel engines. Each technology is evaluated for its potential emission control benefits, as well as its cost and effect on fuel economy and durability.

  2. Inhibitory Control and L2 Proficiency Modulate Bilingual Language Production: Evidence from Spontaneous Monologue and Dialogue Speech

    PubMed Central

    Pivneva, Irina; Palmer, Caroline; Titone, Debra

    2012-01-01

    Bilingual language production requires that speakers recruit inhibitory control (IC) to optimally balance the activation of more than one linguistic system when they produce speech. Moreover, the amount of IC necessary to maintain an optimal balance is likely to vary across individuals as a function of second language (L2) proficiency and inhibitory capacity, as well as the demands of a particular communicative situation. Here, we investigate how these factors relate to bilingual language production across monologue and dialogue spontaneous speech. In these tasks, 42 EnglishFrench and FrenchEnglish bilinguals produced spontaneous speech in their first language (L1) and their L2, with and without a conversational partner. Participants also completed a separate battery that assessed L2 proficiency and inhibitory capacity. The results showed that L2 vs. L1 production was generally more effortful, as was dialogue vs. monologue speech production although the clarity of what was produced was higher for dialogues vs. monologues. As well, language production effort significantly varied as a function of individual differences in L2 proficiency and inhibitory capacity. Taken together, the overall pattern of findings suggests that both increased L2 proficiency and inhibitory capacity relate to efficient language production during spontaneous monologue and dialogue speech. PMID:22438846

  3. Spontaneous ultra-weak light emissions from wheat seedlings are rhythmic and synchronized with the time profile of the local gravimetric tide

    NASA Astrophysics Data System (ADS)

    Moraes, Thiago A.; Barlow, Peter W.; Klingelé, Emile; Gallep, Cristiano M.

    2012-06-01

    Semi-circadian rhythms of spontaneous photon emission from wheat seedlings germinated and grown in a constant environment (darkened chamber) were found to be synchronized with the rhythm of the local gravimetric (lunisolar) tidal acceleration. Time courses of the photon-count curves were also found to match the growth velocity profile of the seedlings. Pair-wise analyses of the data—growth, photon count, and tidal—by local tracking correlation always revealed significant coefficients ( P > 0.7) for more than 80% of any of the time periods considered. Using fast Fourier transform, the photon-count data revealed periodic components similar to those of the gravimetric tide. Time courses of biophoton emissions would appear to be an additional, useful, and innovative tool in both chronobiological and biophysical studies.

  4. Spectroscopic studies, fluorescence quenching by molecular oxygen and amplified spontaneous emission of 1,4-bis [2-(2-pyridyl) vinyl] benzene (P2VB) diolefinic laser dye

    NASA Astrophysics Data System (ADS)

    El-Daly, Samy A.; Ebeid, E. M.

    2014-04-01

    The UV-visible electronic absorption spectra, molar absorptivity, fluorescence spectra, fluorescence quantum yield and excited state lifetime of 1,4-bis [2-(2-pyridyl) vinyl] benzene P2VB were measured in different solvents. The fluorescence quenching of P2VB by molecular oxygen was also studied using lifetime measurements. A 2 10-4 mol dm-3 solution of P2VB in dimethyl formamide (DMF) gave amplified spontaneous emission (ASE) in blue spectral region with emission maximum at 420 nm upon pumping by 337.1 nitrogen laser pulse. The photochemical quantum yields (?c) of trans-cis photoisomerization of P2VB were calculated in different organic solvents. The photoreactivity of P2VB are also studied PMMA matrix.

  5. EUROPEAN ACTIVITIES IN SO2 AND NOX EMISSION CONTROL

    EPA Science Inventory

    The paper gives updated details of major flue gas desulfurization (FGD) and nitrogen oxide (NOx) control installations in the Federal Republic of Germany (West Germany) for coal-fired boilers. The paper reviews applicable government regulations limiting stack emissions, provides ...

  6. Self-organized global control of carbon emissions

    NASA Astrophysics Data System (ADS)

    Zhao, Zhenyuan; Fenn, Daniel J.; Hui, Pak Ming; Johnson, Neil F.

    2010-09-01

    There is much disagreement concerning how best to control global carbon emissions. We explore quantitatively how different control schemes affect the collective emission dynamics of a population of emitting entities. We uncover a complex trade-off which arises between average emissions (affecting the global climate), peak pollution levels (affecting citizens’ everyday health), industrial efficiency (affecting the nation’s economy), frequency of institutional intervention (affecting governmental costs), common information (affecting trading behavior) and market volatility (affecting financial stability). Our findings predict that a self-organized free-market approach at the level of a sector, state, country or continent can provide better control than a top-down regulated scheme in terms of market volatility and monthly pollution peaks. The control of volatility also has important implications for any future derivative carbon emissions market.

  7. Influence of the CdSe quantum dots concentration on the amplified spontaneous emission from the conjugated polymer (MEH-PPV) in solution

    NASA Astrophysics Data System (ADS)

    Ibnaouf, K. H.

    2015-04-01

    The spectral properties of a conjugated polymer poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV) in benzene have been studied intensively. The fluorescence spectra for MEH-PPV, under low concentrations, have shown two peaks around 560 nm and 600 nm, which could be attributed to the monomer and excimer states respectively. In our earlier communication, we had shown that MEH-PPV alone could produce amplified spontaneous emission (ASE) only in its excimeric state (600 nm). The spectral properties of 5 nm size of CdSe (core) quantum dots have been investigated. The fluorescence spectra of CdSe core in benzene showed only one band at 590 nm. Mixtures made of MEH-PPV and CdSe (core) quantum dots have been utilized for studying the amplified spontaneous emission characteristics (ASE) in an organic solution under laser excitation. When the mixture was pumped by the third harmonic of Nd:YAG (355 nm), we observed two ASE peaks; one at 575 nm and another at 595 nm. These ASE peaks could arise from the monomer and excimer states of MEH-PPV. This is perhaps the first report on the influence of quantum dots on the laser from the conjugated polymer MEH-PPV, in liquid solution.

  8. VOC from Vehicular Evaporation Emissions: Status and Control Strategy.

    PubMed

    Liu, Huan; Man, Hanyang; Tschantz, Michael; Wu, Ye; He, Kebin; Hao, Jiming

    2015-12-15

    Vehicular evaporative emissions is an important source of volatile organic carbon (VOC), however, accurate estimation of emission amounts and scientific evaluation of control strategy for these emissions have been neglected outside of the United States. This study provides four kinds of basic emission factors: diurnal, hot soak, permeation, and refueling. Evaporative emissions from the Euro 4 vehicles (1.6 kg/year/car) are about four times those of U.S. vehicles (0.4 kg/year/car). Closing this emissions gap would have a larger impact than the progression from Euro 3 to Euro 6 tailpipe HC emission controls. Even in the first 24 h of parking, China's current reliance upon the European 24 h diurnal standard results in 508 g/vehicle/year emissions, higher than 32 g/vehicle/year from Tier 2 vehicles. The U.S. driving cycle matches Beijing real-world conditions much better on both typical trip length and average speed than current European driving cycles. At least two requirements should be added to the Chinese emissions standards: an onboard refueling vapor recovery to force the canister to be sized sufficiently large, and a 48-h evaporation test requirement to ensure that adequate purging occurs over a shorter drive sequence. PMID:26599318

  9. Emission control cost-effectiveness of alternative-fuel vehicles

    SciTech Connect

    Wang, Q.; Sperling, D.; Olmstead, J.

    1993-06-14

    Although various legislation and regulations have been adopted to promote the use of alternative-fuel vehicles for curbing urban air pollution problems, there is a lack of systematic comparisons of emission control cost-effectiveness among various alternative-fuel vehicle types. In this paper, life-cycle emission reductions and life-cycle costs were estimated for passenger cars fueled with methanol, ethanol, liquefied petroleum gas, compressed natural gas, and electricity. Vehicle emission estimates included both exhaust and evaporative emissions for air pollutants of hydrocarbon, carbon monoxide, nitrogen oxides, and air-toxic pollutants of benzene, formaldehyde, 1,3-butadiene, and acetaldehyde. Vehicle life-cycle cost estimates accounted for vehicle purchase prices, vehicle life, fuel costs, and vehicle maintenance costs. Emission control cost-effectiveness presented in dollars per ton of emission reduction was calculated for each alternative-fuel vehicle types from the estimated vehicle life-cycle emission reductions and costs. Among various alternative-fuel vehicle types, compressed natural gas vehicles are the most cost-effective vehicle type in controlling vehicle emissions. Dedicated methanol vehicles are the next most cost-effective vehicle type. The cost-effectiveness of electric vehicles depends on improvements in electric vehicle battery technology. With low-cost, high-performance batteries, electric vehicles are more cost-effective than methanol, ethanol, and liquified petroleum gas vehicles.

  10. Emission control options for power two wheelers in Europe

    NASA Astrophysics Data System (ADS)

    Ntziachristos, Leonidas; Mamakos, Athanasios; Samaras, Zissis; Xanthopoulos, Anastasios; Iakovou, Eleftherios

    This paper quantifies the emission contribution of motorcycles and mopeds in Europe, in the period 1999-2012. Projections show that these vehicles will emit more than 7% and 20% of total road transport CO and HC, respectively, by the year 2012, if no additional regulatory measures are taken. In contrast, they will continue to be negligible NO x (0.7%) and CO 2 (<1%) emitters, while their particulate matter (PM) emission contribution is expected to decline to below 1% in the future. The relative importance of their emissions, however, increases in urban environments, especially in southern European countries, which host large fleets of small two wheelers. Hence, further regulatory measures are being considered which include durability requirements for the emission controls, in-use compliance and roadworthiness procedures, on-board diagnostics, control of evaporation emissions, PM specific measures and new steps for emission standards. The study quantifies the environmental benefits and the costs associated with each measure, and calculates cost-effectiveness figures which may be used to evaluate each policy option. Results show that for the reduction of HC emissions, both evaporation control and roadworthiness tests are cost-effective while a further tightening of the emission standards for mopeds will bring the largest benefit. Additionally, on-board diagnosis for motorcycles is found to be an expensive measure with questionable effectiveness, while the replacement of mineral with synthetic lubricants would bring clear benefits with respect to PM of 2-stroke engines.

  11. Emission current control system for multiple hollow cathode devices

    NASA Technical Reports Server (NTRS)

    Beattie, John R. (Inventor); Hancock, Donald J. (Inventor)

    1988-01-01

    An emission current control system for balancing the individual emission currents from an array of hollow cathodes has current sensors for determining the current drawn by each cathode from a power supply. Each current sensor has an output signal which has a magnitude proportional to the current. The current sensor output signals are averaged, the average value so obtained being applied to a respective controller for controlling the flow of an ion source material through each cathode. Also applied to each controller are the respective sensor output signals for each cathode and a common reference signal. The flow of source material through each hollow cathode is thereby made proportional to the current drawn by that cathode, the average current drawn by all of the cathodes, and the reference signal. Thus, the emission current of each cathode is controlled such that each is made substantially equal to the emission current of each of the other cathodes. When utilized as a component of a multiple hollow cathode ion propulsion motor, the emission current control system of the invention provides for balancing the thrust of the motor about the thrust axis and also for preventing premature failure of a hollow cathode source due to operation above a maximum rated emission current.

  12. Glutamatergic system controls synchronization of spontaneous neuronal activity in the murine neonatal entorhinal cortex.

    PubMed

    Unichenko, Petr; Yang, Jeng-Wei; Luhmann, Heiko J; Kirischuk, Sergei

    2015-07-01

    Synchronized spontaneous neuronal activity is a characteristic feature of the developing brain. Rhythmic network discharges in the neonatal medial entorhinal cortex (mEC) in vitro depend on activation of ionotropic glutamate receptors, but spontaneously active neurons are required for their initiation. Field potential recordings revealed synchronized neuronal activity in the mEC in vivo developmentally earlier than in vitro. We suggested that not only ionotropic receptors, but also other components of the glutamatergic system modulate neuronal activity in the mEC. Ca(2+) imaging was used to record neuronal activity in neonatal murine brain slices. Two types of spontaneous events were distinguished: global synchronous discharges (synchronous activity) and asynchronously (not synchronized with global discharges) active cells (asynchronous activity). AMPA receptor blockade strongly reduced the frequency of synchronous discharges, while NMDA receptor inhibition was less effective. AMPA and NMDA receptor blockade or activation of group 2/3 metabotropic glutamate receptors (mGluR2/3) completely suppressed synchronous discharges and increased the number of active cells. Blockade of glutamate transporters with DL-TBOA led to NMDA receptor-mediated hyper-synchronization of neuronal activity. Inhibition of NMDA receptors in the presence of DL-TBOA failed to restore synchronous discharges. The latter were partially reestablished only after blockade of mGluR2/3. We conclude that the glutamatergic system can influence neuronal activity via different receptors/mechanisms. As both NMDA and mGluR2/3 receptors have a high affinity for glutamate, changes in extracellular glutamate levels resulting for instance from glutamate transporter malfunction can balance neuronal activity in the mEC, affecting in turn synapse and network formation. PMID:25163767

  13. Insertion/deletion polymorphism in intron 16 of ACE gene in idiopathic recurrent spontaneous abortion: case-control study, systematic review and meta-analysis.

    PubMed

    Pereza, Nina; Ostojić, Saša; Zdravčević, Matea; Volk, Marija; Kapović, Miljenko; Peterlin, Borut

    2016-02-01

    The insertion/deletion (I/D) polymorphism in intron 16 of the angiotensin I-converting enzyme gene (ACE) has been extensively studied as a predisposing factor for idiopathic recurrent spontaneous abortion (IRSA). A case-control study including 149 women with ≥3 spontaneous abortions and 149 controls was performed to test the association of ACE I/D polymorphism with IRSA. A systematic review was conducted of previous case-control studies, with strict selection criteria for meta-analyses. We also aimed to evaluate the potential differences in summary estimates between studies defining IRSA as ≥2 and ≥3 spontaneous abortions. Genotyping was performed by PCR, and systematic review conducted using PubMed and Scopus. There was no association of the polymorphism with IRSA in Slovenian women. Sixteen case-control studies, showing substantial differences regarding IRSA definition and selection criteria for women were identified. Meta-analysis was performed and included four studies defining IRSA as ≥2 spontaneous abortions and the current study, which defined IRSA as ≥3 spontaneous abortions. Based on random effects model, meta-analysis conducted on 1192 patients and 736 controls showed no association with IRSA under dominant(DD+IDvsII) and recessive(DDvsID+II) genetic models. Well-designed studies are needed to evaluate the role of ACE I/D polymorphism in IRSA defined as ≥3 spontaneous abortions. PMID:26673102

  14. Electric-utility emissions: control strategies and costs

    SciTech Connect

    Van Horn, A.; Arpi, D.; Bowen, C.; Chapman, R.; Cooper, R.; Greenfield, S.; Moffett, M.; Wells, M.

    1981-04-01

    The Utility Simulation Model has been used to project the emissions, costs, and operating decisions of the electric utilities for each year between 1980 and 2000. For each steam generating unit in the United States, the model simulates the compliance decision, including choice of fuels and pollution controls, as well as emissions and pollution control costs. Results are aggregated to state, regional, and national levels. The results presented here, summarized by strategy for selected years, include SO/sub 2/ and NO/sub x/ emissions, annual revenue requirements, the average price of electricity, dollars per ton of SO/sub 2/ reduced, coal capacity with FGD, utility fuel consumption, and regional production of coal for utility consumption. Because the strategies analyzed were aimed at SO/sub 2/ reduction, the results focus on the emissions and costs of controlling SO/sub 2/. This report is not intended to provide complete analysis and interpretation of the numerical results given in Section 3.

  15. The disrupted basal ganglia and behavioural control: an integrative cross-domain perspective of spontaneous stereotypy.

    PubMed

    McBride, Sebastian D; Parker, Matthew O

    2015-01-01

    Spontaneous stereotypic behaviour (SB) is common in many captive animal species, as well as in humans with some severe psychiatric disorders, and is often cited as being related to general basal ganglia dysfunction. Despite this assertion, there is little in the literature examining SB specifically in terms of the basal ganglia mechanics. In this review, we attempt to fill this gap by offering an integrative, cross-domain perspective of SB by linking what we currently understand about the SB phenotype with the ever-growing literature on the anatomy and functionality of the basal ganglia. After outlining current models of SB from different theoretical perspectives, we offer a broad but detailed overview of normally functioning basal ganglia mechanics, and attempt to link this with current neurophysiological evidence related to spontaneous SB. Based on this we present an empirically derived theoretical framework, which proposes that SB is the result of a dysfunctional action selection system that may reflect dysregulation of excitatory (direct) and inhibitory (indirect and hyperdirect) pathways as well as alterations in mechanisms of behavioural switching. This approach also suggests behaviours that specifically become stereotypic may reflect inbuilt low selection threshold behavioural sequences associated with early development and the species-specific ethogram or, low threshold behavioural sequences that are the result of stress-induced dopamine exposure at the time of performance. PMID:25052167

  16. Historical evaluation of vehicle emission control in Guangzhou based on a multi-year emission inventory

    NASA Astrophysics Data System (ADS)

    Zhang, Shaojun; Wu, Ye; Liu, Huan; Wu, Xiaomeng; Zhou, Yu; Yao, Zhiliang; Fu, Lixin; He, Kebin; Hao, Jiming

    2013-09-01

    The Guangzhou government adopted many vehicle emission control policies and strategies during the five-year preparation (2005-2009) to host the 2010 Asian Games. This study established a multi-year emission inventory for vehicles in Guangzhou during 2005-2009 and estimated the uncertainty in total vehicle emissions by taking the assumed uncertainties in fleet-average emission factors and annual mileage into account. In 2009, the estimated total vehicle emissions in Guangzhou were 313 000 (242 000-387 000) tons of CO, 60 900 (54 000-70 200) tons of THC, 65 600 (56 800-74 100) tons of NOx and 2740 (2100-3400) tons of PM10. Vehicle emissions within the urban area of Guangzhou were estimated to be responsible for 40% of total gaseous pollutants and 25% of total PM10 in the entire city. Although vehicle use intensity increased rapidly in Guangzhou during 2005-2009, vehicle emissions were estimated to have been reduced by 12% for CO, 21% for THC and 20% for PM10 relative to those in 2005. NOx emissions were estimated to have remained almost constant during this period. Compared to the "without control" scenario, 19% (15%-23%) of CO, 20% (18%-23%) of THC, 9% (8%-10%) of NOx and 16% (12%-20%) of PM10 were estimated to have been mitigated from a combination of the implementation of Euro III standards for light-duty vehicles (LDVs) and heavy-duty diesel vehicles and improvement of fuel quality. This study also evaluated several enhanced vehicle emission control actions taken recently. For example, the enhanced I/M program for LDVs was estimated to reduce 11% (9%-14%) of CO, 9% (8%-10%) of THC and 2% (2%-3%) of NOx relative to total vehicle emissions in 2009. Total emission reductions by temporary traffic controls for the Asian Games were estimated equivalent to 9% (7%-11%) of CO, 9% (8%-10%) of THC, 5% (5%-6%) of NOx and 10% (8%-13%) of PM10 estimated total vehicle emissions in 2009. Those controls are essential to further vehicle emission mitigation in Guangzhou required by the new National Ambient Air Quality Standards.

  17. CONTROLLING AGRICULTURAL EMISSIONS OF METHYL BROMIDE.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During the last 40 to 50 years, methyl bromide (MeBr) has been used to sterilize soils in preparation to planting various high-cash-value fruit and vegetable crops throughout the world. MeBr is a highly toxic chemical and is very effective in controlling a variety of soil-borne pests, such as nemato...

  18. Optical control of the emission direction of a quantum dot

    SciTech Connect

    Luxmoore, I. J.; Wasley, N. A.; Fox, A. M.; Skolnick, M. S.; Ramsay, A. J.; Thijssen, A. C. T.; Oulton, R.; Hugues, M.; CNRS-CRHEA, rue Bernard Grgory, 06560 Valbonne

    2013-12-09

    Using the helicity of a non-resonant excitation laser, control over the emission direction of an InAs/GaAs quantum dot is demonstrated. The quantum dot is located off-center in a crossed-waveguide structure, such that photons of opposite circular polarization are emitted into opposite waveguide directions. By preferentially exciting spin-polarized excitons, the direction of emission can therefore be controlled. The directional control is quantified by using the ratio of the intensity of the light coupled into the two waveguides, which reaches a maximum of 35%.

  19. CONTROL OF SULFUR EMISSIONS FROM OIL SHALE RETORTS

    EPA Science Inventory

    The objectives of this study were to determine the best available control technology (BACT) for control of sulfur emissions from oil shale processing facilities and then to develop a design for a mobile slipstream pilot plant that could be used to test and demonstrate that techno...

  20. SUMMARY REPORT CONTROL OF NOX EMISSIONS BY REBURNING

    EPA Science Inventory

    This report covers NOx control employing reburning technology: A new, effective method of controlling NOx emissions from a wide range of stationary combustion sources including large, coal-fired, utility boilers. Although reburning potentially is applicable ...

  1. CONTROL OF PARTICULATE EMISSIONS IN THE PRIMARY NONFERROUS METALS INDUSTRIES

    EPA Science Inventory

    The purpose of the symposium on 'Control of Particulate Emissions in the Primary Nonferrous Metals Industries' was to provide a forum for the exchange of knowledge and new ideas on particulate control technology with emphasis on industrial applications of environmental particulat...

  2. 40 CFR Appendix III to Part 1037 - Emission Control Identifiers

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM NEW HEAVY-DUTY MOTOR VEHICLES Pt. 1037, App. III Appendix III... of idling -IRTE—Expiring engine shutoff Tires -LRRA—Low rolling resistance tires (all) -LRRD—Low rolling resistance tires (drive) -LRRS—Low rolling resistance tires (steer) Aerodynamic Components...

  3. 40 CFR Appendix III to Part 1037 - Emission Control Identifiers

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... POLLUTION CONTROLS CONTROL OF EMISSIONS FROM NEW HEAVY-DUTY MOTOR VEHICLES Pt. 1037, App. III Appendix III... of idling -IRTE—Expiring engine shutoff Tires -LRRA—Low rolling resistance tires (all) -LRRD—Low rolling resistance tires (drive) -LRRS—Low rolling resistance tires (steer) Aerodynamic Components...

  4. The foxa2 Gene Controls the Birth and Spontaneous Degeneration of Dopamine Neurons in Old Age

    PubMed Central

    Awatramani, Rajeshwar B; McKay, Ronald D. G

    2007-01-01

    Parkinson disease affects more than 1% of the population over 60 y old. The dominant models for Parkinson disease are based on the use of chemical toxins to kill dopamine neurons, but do not address the risk factors that normally increase with age. Forkhead transcription factors are critical regulators of survival and longevity. The forkhead transcription factor, foxa2, is specifically expressed in adult dopamine neurons and their precursors in the medial floor plate. Gain- and loss-of-function experiments show this gene, foxa2, is required to generate dopamine neurons during fetal development and from embryonic stem cells. Mice carrying only one copy of the foxa2 gene show abnormalities in motor behavior in old age and an associated progressive loss of dopamine neurons. Manipulating forkhead function may regulate both the birth of dopamine neurons and their spontaneous death, two major goals of regenerative medicine. PMID:18076286

  5. Carrier-mediated transport controls hydroxyproline catabolism in heart mitochondria from spontaneously hypertensive rat.

    PubMed

    Atlante, A; Seccia, T M; Marra, E; Minervini, G M; Vulpis, V; Pirrelli, A; Passarella, S

    1996-11-01

    In this study we have investigated hydroxyproline transport in rat heart mitochondria and, in particular, in heart left ventricle mitochondria isolated from both spontaneously hypertensive and Wistar-Kyoto rats. Hydroxyproline uptake by mitochondria, where its catabolism takes place, occurs via a carrier-mediated process as demonstrated by the occurrence of both saturation kinetics and the inhibition shown by phenylsuccinate and the thiol reagent mersalyl. In any case, hydroxyproline transport was found to limit the rate of mitochondrial hydroxyproline catabolism. A significant change in Vmax and Km values was found in mitochondria from hypertensive/hypertrophied rats in which the Km value decreases and the Vmax value increases with respect to normotensive rats, thus accounting for the increase of hydroxyproline metabolism due to its increased concentration in a hypertrophic/hypertensive state. PMID:8915003

  6. Complex instability of axially compressed tubular lipid membrane with controlled spontaneous curvature.

    PubMed

    Golushko, I Yu; Rochal, S B; Lorman, V L

    2015-10-01

    Tubular lipid membranes (TLMs) are formed by an external pulling force from artificial or biological bilayer vesicles and can be subsequently stabilized by incorporating proteins or amphiphilic polymers into the lipid bilayer. The arising spontaneous curvature of the lipid sheet allows switching off the pulling force without TLM destabilization. However, here we show that during this process two different thermal fluctuation modes drastically increase their amplitudes making fluctuations of the TLM much greater than its radius. Due to the system's proximity to the critical fluctuation point, a weak axial compressive force is sufficient to destabilize the TLM. Its absolute value is shown to be much smaller than that of the pulling force required for the initial lipid nanotube formation. Induced complex instability was studied in the frame of Landau phase transition theory. The process involves two consecutive second-order phase transitions and leads to the tube deformation combining annular corrugation with completely unconventional chiral buckling. PMID:26507403

  7. Systems and methods for controlling diesel engine emissions

    DOEpatents

    Webb, Cynthia Chaffin; Weber, Phillip Anthony; Khair, Magdi K.

    2004-06-01

    Systems and methods for controlling diesel engine emissions, including, for example, oxides of nitrogen emissions, particulate matter emissions, and the like. The emission control system according to this invention is provided in the exhaust passageway of a diesel engine and includes a catalyst-based particulate filter; and first and second lean NO.sub.x trap systems coupled to the catalyst-based particulate filter. The first and second lean NO.sub.x trap systems are arranged in a parallel flow configuration with each other. Each of the first and second lean NO.sub.x trap systems include a carbon monoxide generating catalyst device, a sulfur trap device, a lean NO.sub.x device, a supplemental fuel injector device, and a plurality of flow diverter devices.

  8. Modeling study of natural emissions, source apportionment, and emission control of atmospheric mercury

    NASA Astrophysics Data System (ADS)

    Shetty, Suraj K.

    Mercury (Hg) is a toxic pollutant and is important to understand its cycling in the environment. In this dissertation, a number of modeling investigations were conducted to better understand the emission from natural surfaces, the source-receptor relationship of the emissions, and emission reduction of atmospheric mercury. The first part of this work estimates mercury emissions from vegetation, soil and water surfaces using a number of natural emission processors and detailed (LAI) Leaf Area Index data from GIS (Geographic Information System) satellite products. East Asian domain was chosen as it contributes nearly 50% of the global anthropogenic mercury emissions into the atmosphere. The estimated annual natural mercury emissions (gaseous elemental mercury) in the domain are 834 Mg yr-1 with 462 Mg yr-1 contributing from China. Compared to anthropogenic sources, natural sources show greater seasonal variability (highest in simmer). The emissions are significant, sometimes dominant, contributors to total mercury emission in the regions. The estimates provide possible explanation for the gaps between the anthropogenic emission estimates based on activity data and the emission inferred from field observations in the regions. To understand the contribution of domestic emissions to mercury deposition in the United States, the second part of the work applies the mercury model of Community Multi-scale Air Quality Modeling system (CMAQ-Hg v4.6) to apportion the various emission sources attributing to the mercury wet and dry deposition in the 6 United States receptor regions. Contributions to mercury deposition from electric generating units (EGU), iron and steel industry (IRST), industrial point sources excluding EGU and IRST (OIPM), the remaining anthropogenic sources (RA), natural processes (NAT), and out-of-boundary transport (BC) in domain was estimated. The model results for 2005 compared reasonably well to field observations made by MDN (Mercury Deposition Network) and CAMNet (Canadian Atmospheric Mercury Measurement Network). The model estimated a total deposition of 474 Mg yr-1 to the CONUS (Contiguous United States) domain, with two-thirds being dry deposited. Reactive gaseous mercury contributed the most to 60% of deposition. Emission speciation distribution is a key factor for local deposition as contribution from large point sources can be as high as 75% near (< 100 km) the emission sources, indicating that emission reduction may result in direct deposition decrease near the source locations. Among the sources, BC contributes to about 68% to 91% of total deposition. Excluding the BC's contribution, EGU contributes to nearly 50% of deposition caused by CONUS emissions in the Northeast, Southeast and East Central regions, while emissions from natural processes are more important in the Pacific and West Central regions (contributing up to 40% of deposition). The modeling results implies that implementation of the new emission standards proposed by USEPA (United States Environmental Protection Agency) would significantly benefit regions that have larger contributions from EGU sources. Control of mercury emissions from coal combustion processes has attracted great attention due to its toxicity and the emission-control regulations and has lead to advancement in state-of-the-art control technologies that alleviate the impact of mercury on ecosystem and human health. This part of the work applies a sorption model to simulate adsorption of mercury in flue gases, onto a confined-bed of activated carbon. The model's performances were studied at various flue gas flow rates, inlet mercury concentrations and adsorption bed temperatures. The process simulated a flue gas, with inlet mercury concentration of 300 ppb, entering at a velocity of 0.3 m s-1 from the bottom into a fixed bed (inside bed diameter of 1 m and 3 m bed height; bed temperature of 25 C) of activated carbon (particle size of 0.004 m with density of 0.5 g cm-3 and surface area of 90.25 cm2 g -1). The model result demonstrated that a batch of activated carbon

  9. Anthropogenic mercury flows in India and impacts of emission controls.

    PubMed

    Burger Chakraborty, Laura; Qureshi, Asif; Vadenbo, Carl; Hellweg, Stefanie

    2013-08-01

    India is a major emitter of mercury, a pollutant of global importance. However, quantitative information on mercury flows in the country is lacking. Here, we quantify major transfer pathways for anthropogenic mercury, its emissions to the environment (air, water, soil), and storage in consumer products and anthropogenic sinks (e.g., landfills) in India in the period 2001-2020, and evaluate the potential influence of six pollution control measures. Total mercury emissions in India were approximately 415 tonnes in 2001, 310 tonnes in 2010, and are projected to rise to 540 tonnes in 2020. In 2010, 76% of these emissions went to the atmosphere. The most important emission sources to atmosphere are coal power plants and zinc production. Pesticides were the most important source for emissions to soil in 2005 and dental amalgam in later years. Mercury stocks in products rose from 700 tonnes in 2001 to 1125 tonnes in 2010, and in landfills and ash-made structures (e.g., embankments) from 920 tonnes in 2001 to 1450 tonnes in 2010. These stocks are expected to rise further and may be regarded as stored toxicity, which may become a concern in the future. Total mercury emissions can be reduced by about 50% by combining pollution control measures that target different mercury emission sources. PMID:23834017

  10. Emissions and fuel economy effects of vehicle exhaust emission control device (revision). Technical report

    SciTech Connect

    Johnson, H.

    1998-10-01

    This report describes testing by EPA of the Vehicle Exhaust Emission Control Device (VEECD) retrofit device under Section 32918 of Title 49 U.S.C. Retrofit Devices (RD). The VEECD is described by the developer in the international patent application as an embodiment of air bleed principle. It is intended to be retrofitted to vehicles produced without any, or with earlier-technology emission control systems. The developer claims (RD Application Appendix A) that the valve significantly reduces CO and HC emissions without substantially increasing CO{sub 2} or NOx emissions. Incidental city fuel economy enhancement was also claimed. Non-FTP test data obtained for 1986/87 European vehicles from two laboratories in the UK was submitted. This data (Appendix B) was analyzed using the t-test for the difference of constant speed data (30/60/85MPH) at 95% confidence level.

  11. Positional control of plasmonic fields and electron emission

    SciTech Connect

    Word, R. C.; Fitzgerald, J. P. S.; Könenkamp, R.

    2014-09-15

    We report the positional control of plasmonic fields and electron emission in a continuous gap antenna structure of sub-micron size. We show experimentally that a nanoscale area of plasmon-enhanced electron emission can be motioned by changing the polarization of an exciting optical beam of 800 nm wavelength. Finite-difference calculations are presented to support the experiments and to show that the plasmon-enhanced electric field distribution of the antenna can be motioned precisely and predictively.

  12. Primary production control of methane emission from wetlands

    NASA Technical Reports Server (NTRS)

    Whiting, G. J.; Chanton, J. P.

    1993-01-01

    Based on simultaneous measurements of CO2 and CH4 exchange in wetlands extending from subarctic peatlands to subtropical marshes, a positive correlation between CH4 emission and net ecosystem production is reported. It is suggested that net ecosystem production is a master variable integrating many factors which control CH4 emission in vegetated wetlands. It is found that about 3 percent of the daily net ecosystem production is emitted back to the atmosphere as CH4. With projected stimulation of primary production and soil microbial activity in wetlands associated with elevated atmospheric CO2 concentration, the potential for increasing CH4 emission from inundated wetlands, further enhancing the greenhouse effect, is examined.

  13. Environmental controls over methyl halide emissions from rice paddies

    NASA Astrophysics Data System (ADS)

    Redeker, K. R.; Cicerone, R. J.

    2004-03-01

    This paper examines primary controlling factors that affect methyl halide emissions from rice paddy ecosystems. Observations of four cultivars under multiple growth conditions during studies in commercial fields and the University of California, Irvine, greenhouse lead to the conclusion that daily emissions of methyl halides are primarily determined by the growth stage of the rice plant, with the exception that methyl chloride emissions show no clear seasonal pattern. Methyl chloride emissions appear to be more from the paddy water and/or soil as opposed to the plants; however, in soils with high chloride content, these emissions appear to peak during the reproductive phase. Strong secondary influences include air temperature, soil halide concentration, and soil pore water saturation. The cultivars studied had statistically separate seasonally integrated emissions. Irradiant light and aboveground biomass appear to have little effect on emissions. Emissions of methyl chloride, methyl bromide, and methyl iodide are estimated to be 3.5, 2.3, and 48 mg/m2/yr, or 5.3, 3.5, and 72 Gg/yr, from rice paddies globally.

  14. Suitability of nanodiamond nitrogen-vacancy centers for spontaneous emission control experiments

    NASA Astrophysics Data System (ADS)

    Mohtashami, Abbas; Femius Koenderink, A.

    2013-04-01

    Nitrogen-vacancy (NV) centers in diamond are generally recognized as highly promising as indefinitely stable highly efficient single-photon sources. We report an experimental quantification of the brightness, radiative decay rate, nonradiative decay rate and quantum efficiency of single NV centers in diamond nanocrystals. Our experiments show that the commonly observed large spread in fluorescence decay rates of NV centers in nanodiamond is inconsistent with the common explanation of large nanophotonic mode-density variations in the ultra-small high-index crystals at near-unity quantum efficiency. We report that NV centers in 25 nm nanocrystals are essentially insensitive to local density of optical states (LDOS) variations that we induce at a dielectric interface by using liquids to vary the refractive index, and propose that quantum efficiencies in such nanocrystals are widely distributed between 0 and 20%. For single NV centers in larger 100 nm nanocrystals, we show that decay rate changes can be reversibly induced by nanomechanically approaching a mirror to change the LDOS. Using this scanning mirror method, for the first time we report calibrated quantum efficiencies of NV centers, and show that different but nominally identical nanocrystals have widely distributed quantum efficiencies between 10 and 90%. Our measurements imply that nanocrystals that are to be assembled into hybrid photonic structures for cavity QED should first be individually screened to assess fluorescence properties in detail.

  15. Acoustic emission feedback control for control of boiling in a microwave oven

    DOEpatents

    White, Terry L.

    1991-01-01

    An acoustic emission based feedback system for controlling the boiling level of a liquid medium in a microwave oven is provided. The acoustic emissions from the medium correlated with surface boiling is used to generate a feedback control signal proportional to the level of boiling of the medium. This signal is applied to a power controller to automatically and continuoulsly vary the power applied to the oven to control the boiling at a selected level.

  16. Subtask 1 report: emission control system identification. Task 25

    SciTech Connect

    Not Available

    1982-10-22

    The emphasis here is the identification of emission control systems through information contained in the vehicle identification number (VIN). The data base which maps each combination of carline and engine symbol into the possible engine families is described in detail. The methods used in developing this data base are summarized. The instances in which major features of the emission control system can not be determined unambiguously from the VIN are identified. Recommendations are presented for resolving the ambiguities with the assistance of auto manufacturers. The ability of the several manufacturers to assist in further decoding of VINs and is reported and the information presently available on costs of doing so is provided. Data files that will be used to extract manufacturer, carline, and engine symbols from VINs and then access the master VIN/engine family data base are listed. The master data base is listed in its entirety. The cases of ambiguous emission control identification are listed. (MHR)

  17. Interaction of infiltrated colloidal PbS nanocrystals with high Q/V silicon photonic bandgap nanocavities for near-infrared enhanced spontaneous emissions

    NASA Astrophysics Data System (ADS)

    Bose, Ranojoy; Talapin, Dmitri V.; Yang, Xiaodong; Harniman, Richard J.; Nguyen, Phung T.; Wong, Chee Wei

    2005-11-01

    We study the interaction of silicon photonic crystal nanocavities with infiltrated colloidal PbS nanocrystals as a viable and efficient source for achieving indistinguishable and single photons. Nanocrystal-nanocavity coupling is predicted at near-infrared wavelengths, suggesting the possibility towards exciting silicon-based nanophotonic lasers, and novel efficient sources for fiber and silicon-based quantum information networks and systems. Two effective designs for nanocrystal-nanocavity coupling are illustrated that exhibit moderate to high cavity quality factors, and ultra-small modal volumes for spontaneous emission enhancements. It is shown that in principle our system can approach the observation of strong exciton-cavity coupling in a solid-state implementation at room temperature.

  18. The recombination mechanisms leading to amplified spontaneous emission at the true-green wavelength in CH3NH3PbBr3 perovskites

    NASA Astrophysics Data System (ADS)

    Priante, D.; Dursun, I.; Alias, M. S.; Shi, D.; Melnikov, V. A.; Ng, T. K.; Mohammed, O. F.; Bakr, O. M.; Ooi, B. S.

    2015-02-01

    We investigated the mechanisms of radiative recombination in a CH3NH3PbBr3 hybrid perovskite material using low-temperature, power-dependent (77 K), and temperature-dependent photoluminescence (PL) measurements. Two bound-excitonic radiative transitions related to grain size inhomogeneity were identified. Both transitions led to PL spectra broadening as a result of concurrent blue and red shifts of these excitonic peaks. The red-shifted bound-excitonic peak dominated at high PL excitation led to a true-green wavelength of 553 nm for CH3NH3PbBr3 powders that are encapsulated in polydimethylsiloxane. Amplified spontaneous emission was eventually achieved for an excitation threshold energy of approximately 350 ?J/cm2. Our results provide a platform for potential extension towards a true-green light-emitting device for solid-state lighting and display applications.

  19. Inducing quantum coherence via decays and incoherent pumping with application to population trapping, lasing without inversion, and quenching of spontaneous emission

    SciTech Connect

    Kozlov, Victor V.; Rostovtsev, Yuri; Scully, Marlan O.

    2006-12-15

    Quantum interference in a decaying three-level system of V type with degenerate upper levels driven by a single incoherent field is shown to lead to a coherent population-trapping state and more generally to a population-locked state. The latter is a state with half the population locked in two upper states regardless of the strength of incoherent pumping and decay rates. We reveal the mechanism by which half the population is pumped to the upper states no matter how weak is the incoherent pumping. Transient regimes of gain without inversion and inversion without gain are demonstrated. Quenching of spontaneous emission due to electron collisions is also discussed in support of the experiments and ideas of Suckewer and [Phys. Rev. Lett. 60, 1122 (1988)].

  20. Mercury emissions control technologies for mixed waste thermal treatment

    SciTech Connect

    Chambers, A.; Knecht, M.; Soelberg, N.; Eaton, D.; Roberts, D.; Broderick, T.

    1997-12-31

    EPA has identified wet scrubbing at low mercury feedrates, as well as carbon adsorption via carbon injection into the offgas or via flow through fixed carbon beds, as control technologies that can be used to meet the proposed Maximum Achievable Control Technology (MACT) rule limit for mercury emissions from hazardous waste incinerators. DOE is currently funding demonstrations of gold amalgamation that may also control mercury to the desired levels. Performance data from a variety of sources was reviewed to determine ranges of achievable mercury control. Preliminary costs were estimated for using these technologies to control mercury emissions from mixed waste incineration. Mercury emissions control for mixed waste incineration may need to be more efficient than for incineration of other hazardous wastes because of higher mercury concentrations in some mixed waste streams. However, mercury control performance data for wet scrubbing and carbon adsorption is highly variable. More information is needed to demonstrate control efficiencies that are achievable under various design and operating conditions for wet scrubbing, carbon adsorption, and gold amalgamation technologies. Given certain assumptions made in this study, capital costs, operating costs, and lifecycle costs for carbon injection, carbon beds, and gold amalgamation generally vary for different assumed mercury feedrates and for different offgas flowrates. Assuming that these technologies can in fact provide the necessary mercury control performance, each of these technologies may be less costly than the others for certain mercury feedrates and the offgas flowrates.

  1. New emission controls for Missouri batch-type charcoal kilns

    SciTech Connect

    Yronwode, P.; Graf, W.J.

    1999-07-01

    Charcoal kilns have been exempted from air emission regulation in the state of Missouri. Today, 80% of US charcoal production takes place in Missouri. As a result of a petition filed by people in the area around an installation in southern Missouri, the US Environmental Protection Agency (EPA) set up air monitors and measured ambient air levels at that charcoal manufacturing installation. These monitors yielded the highest particulate matter less than 10 micron (PM{sub 10}) levels ever recorded in the state. Earlier stack testing at another charcoal manufacturing installation indicated that toxics and carcinogens are present in charcoal kiln air emissions. A Charcoal Kiln Workgroup was formed to determine the Best Available Control Technology (BACT) for charcoal kilns and to draft a charcoal kiln rule that requires BACT. The BACT report determined that afterburners were suitable for controlling emissions from batch-type charcoal kilns. In addition, the charcoal industry supported incorporating the BACT limits and requirements into an enforceable state rule and submitting this rule to the EPA for federal approval. A consent agreement between the EPA and three major charcoal companies was signed with provisions to install, operate, and maintain emission control devices on charcoal kilns. This agreement was to settle complaints alleging that the three major charcoal producers had failed to report toxic air emissions to federal and state regulators. The agreement provided that industry would install control devices on a set schedule with some charcoal kilns being shut down.

  2. Coal-fueled diesel technology development Emissions Control

    SciTech Connect

    Van Kleunen, W.; Kaldor, S.; Gal, E.; Mengel, M.; Arnold, M.

    1994-01-01

    GEESI Emissions Control program activity ranged from control concept testing of 10 CFM slipstream from a CWS fuel single cylinder research diesel engine to the design, installation, and operation of a full-size Emissions Control system for a full-size CWS fuel diesel engine designed for locomotive operation.Early 10 CFM slipstream testing program activity was performed to determine Emissions Characteristics and to evaluate Emissions Control concepts such a Barrier filtration, Granular bed filtration, and Cyclone particulate collection for reduction of particulate and gaseous emissions. Use of sorbent injection into the engine exhaust gas upstream of the barrier filter or use of sorbent media in the granular bed filter were found to provide reduction of exhaust gas SO{sub 2} and NO{sub x} in addition to collection of ash particulate. Emergence of the use of barrier filtration as a most practical Emissions Control concept disclosed a need to improve cleanability of the filter media in order to avoid reduction of turbocharger performance by excessive barrier filter pressure drop. The next progression of program activity, after the slipstream feasibility state, was 500 CFM cold flow testing of control system concepts. The successful completion of 500 CFM cold flow testing of the Envelope Filter led to a subsequent progression to a similar configuration Envelope Filter designed to operate at 500 CFM hot gas flow from the CWS fuel research diesel engine in the GETS engine test laboratory. This Envelope Filter included the design aspect proven by cold flow testing as well as optimization of the selection of the installed filter media.

  3. Safety hazards associated with air-emission controls

    SciTech Connect

    Ozog, H.; Erny, W.J.

    2000-03-31

    Air-emission controls have been installed in refineries since 1990 to comply with environmental regulations such as Benzene NESHAP and the Clean Air Act. Companies have experienced incidents associated with these air-emission controls, but the extent of the problem could not be quantified. In this paper, the authors present the results of a survey of the member companies of API's Safety and Fire Protection Subcommittee (SFPS) to determine the number and type of air-emission controls which have been installed, and the types of incidents which they have experienced. The survey was completed in February 1998. The authors obtained responses from eight SFPS member companies, including 16 refineries, 1 gas plant, 2 chemical plants and 1 marketing terminal. Carbon canisters are the most common air-emission control installed (769) and there have been 10 unique incidents associated with carbon canisters/beds, of which 5 resulted in injury or significant property damage. Given the prevalence of carbon canister installations and the associated incidents, the SFPS Emission Control Safety Workgroups decided to focus mitigation/prevention efforts on carbon canisters. If carbon beds are overloaded with volatile organic compounds (VOCs) or highly reactive materials, they can overheat and catch fire, which can then provide an ignition source for VOC vapors. The industry however does not appear to be fully aware of the hazards associated with the use of carbon canisters and the limitations on their use. The objective of this project was to research and evaluate the safety hazards associated with certain air-emission control systems used in the petroleum industry and to develop recommendations to address these hazards.

  4. Coal-fueled diesel technology development emissions control

    NASA Astrophysics Data System (ADS)

    Vankleunen, W.; Kaldor, S.; Gal, E.; Mengel, M.; Arnold, M.

    1994-01-01

    General Electric Environmental Services, Inc. (GEESI), Emissions Control program activity ranged from control concept testing of 10 CFM slipstream from a coal-water-slurry (CWS) fuel single cylinder research diesel engine to the design, installation, and operation of a full-size emissions control system for a full-size CWS fuel diesel engine designed for locomotive operation. Early 10 CFM slipstream testing program activity was performed to determine emissions characteristics and to evaluate emissions control concepts such a barrier filtration, granular bed filtration, and cyclone particulate collection for reduction of particulate and gaseous emissions. Use of sorbent injection into the engine exhaust gas upstream of the barrier filter or use of sorbent media in the granular bed filter were found to provide reduction of exhaust gas SO2 and NO(x) in addition to collection of ash particulate. Emergence of the use of barrier filtration as a most practical emissions control concept disclosed a need to improve cleanability of the filter media in order to avoid reduction of turbocharger performance by excessive barrier filter pressure drop. The next progression of program activity, after the slipstream feasibility state, was 500 CFM cold flow testing of control system concepts. The successful completion of 500 CFM cold flow testing of the envelope filter led to a subsequent progression to a similar configuration envelope filter designed to operate at 500 CFM hot gas flow from the CWS fuel research diesel engine in the GETS engine test laboratory. This envelope filter included the design aspect proven by cold flow testing as well as optimization of the selection of the installed filter media.

  5. Emission control valve with internal spring

    SciTech Connect

    Betterton, J.T.; Glover, A.H.; McKee, T.S.; Romanczuk, C.S.

    1990-03-06

    This patent describe, with an internal combustion engine, a crankcase gas flow control device located between the engine crankcase and the engine fuel-air induction. It comprises: a hollow housing defining an inlet at one end, a cylindrical flow passage, a diverging orifice passage and an outlet passage; a slender rod extending coaxially through the cylindrical flow passage and the diverging orifice passage; a tubular valve element within the housing and supported about the slender rod thereby allowing axial movement of the valve element along the rod; a coil-type compression spring extending about the rod and within the tubular valve element, one end of the spring fixedly connected to the rod, the other end of the spring bearing against the tubular valve element tending to move it along the rod toward the housing inlet and away from the diverging orifice passage whereby a gas pressure differential produced between the crankcase and the fuel-air induction causes the valve element to move against the spring force and resultantly the gas flows over the exterior of the valve element without interference by the spring thereby preventing turbulence. The housing has a walled elbow portion between the diverging orifice passage and the outlet whereby the downstream end of the rod is supported by the elbow wall.

  6. Spontaneous oscillations in a model for active control of microvessel diameters.

    PubMed

    Arciero, J C; Secomb, T W

    2012-06-01

    A new theory is presented for the origin of spontaneous oscillations in blood vessel diameters that are observed experimentally in the microcirculation. These oscillations, known as vasomotion, involve timevarying contractions of the vascular smooth muscle in the walls of arterioles. It is shown that such oscillations can arise as a result of interactions between the mechanics of the vessel wall and the dynamics of the active contraction of smooth muscle cells in response to circumferential tension in the wall. A theoretical model is developed in which the diameter and the degree of activation in a vessel are dynamic variables. The model includes effects of wall shear stress and oxygen-dependent metabolic signals on smooth muscle activation and is applied to a single vessel and to simplified network structures. The model equations predict limit cycle oscillations for certain ranges of parameters such as wall shear stress, arterial pressure and oxygen consumption rate. Predicted characteristics of the oscillations, including their sensitivity to arterial pressure, are consistent with experimental observations. PMID:21525236

  7. On the understanding and control of the spontaneous heating of dried tannery wastewater sludge.

    PubMed

    Biasin, A; Della Zassa, M; Zerlottin, M; Refosco, D; Bertani, R; Canu, P

    2014-04-01

    We studied the spontaneous heating of dried sludge produced by treating wastewater mainly originating from tanneries. Heating up to burning has been observed in the presence of air and moisture, starting at ambient temperature. To understand and prevent the process we combined chemical and morphological analyses (ESEM) with thermal activity monitoring in insulated vessels. Selective additions of chemicals, either to amplify or depress the reactivity, have been used to investigate and identify both the chemical mechanism causing the sludge self-heating, and a prevention or a mitigation strategy. FeS additions accelerate the onset of reactivity, while S sustains it over time. On the contrary, Ca(OH)2, Na2CO3, NaHCO3, FeCl2, EDTA, NaClO can limit, up to completely preventing, the exothermic activity. All the experimental evidences show that the reactions supporting the dried sludge self-heating involve the Fe/S/O system. The total suppression of the reactivity requires amounts of additives that are industrially incompatible with waste reduction and economics. The best prevention requires reduction or removal of S and Fe from the dried solid matrix. PMID:24484766

  8. NOx Sensor for Direct Injection Emission Control

    SciTech Connect

    Betteridge, William J

    2006-02-28

    The Electricore/Delphi team continues to leverage the electrochemical planar sensor technology that has produced stoichiometric planar and wide range oxygen sensors as the basis for development of a NOx sensor. Zirconia cell technology with an integrated heater will provide the foundation for the sensor structure. Proven materials and packaging technology will help to ensure a cost-effective approach to the manufacture of this sensor. The electronics technique and interface is considered to be an area where new strategies need to be employed to produce higher S/N ratios of the NOx signal with emphasis on signal stability over time for robustness and durability Both continuous mode and pulse mode control techniques are being evaluated. Packaging the electronics requires careful design and circuit partitioning so that only the necessary signal conditioning electronics are coupled directly in the wiring harness, while the remainder is situated within the ECM for durability and costs reasons. This task continues to be on hold due to the limitation that the definition of the interface electronics was unavailable until very late in the project. The sense element is based on the amperometric method utilizing integrated alumina and zirconia ceramics. Precious metal electrodes are used to form the integrated heater, the cell electrodes and leads. Inside the actual sense cell structure, it is first necessary to separate NOx from the remaining oxygen constituents of the exhaust, without reducing the NOx. Once separated, the NOx will be measured using a measurement cell. Development or test coupons have been used to facilitate material selection and refinement, cell, diffusion barrier, and chamber development. The sense element currently requires elaborate interconnections. To facilitate a robust durable connection, mechanical and metallurgical connections are under investigation. Materials and process refinements continue to play an important role in the development of the sensor.

  9. Environmental controls on Pan-Arctic wetland methane emissions

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Bohn, Theodore; Lettenmaier, Dennis

    2015-04-01

    Environmental conditions such as soil temperature and moisture, incident solar radiation, and atmospheric carbon dioxide concentration are important environmental controls on methane emissions from northern wetlands. We investigated the spatio-temporal distributions of influence of these factors over northern wetland methane emissions via the Variable Infiltration Capacity (VIC) model. We simulated methane emissions from wetlands across the Pan-Arctic domain over the period 1948-2006, with annual average emissions of 35.1±6.7 TgCH4/year. From control simulations that each held one environmental factor constant, we characterized sensitivities to air temperature, precipitation, incident long- and short-wave radiation, and atmospheric [CO2] as a function of average summer air temperature and precipitation. Trade-offs between air temperature and precipitation caused maximal emissions to occur along a line in precipitation-temperature space with a slope of approximately 13 mm month-1 / K, leading to separation of wetlands into various combinations of water-limited and temperature-limited regimes. Emissions from relatively warm and dry wetlands in the southern (permafrost-free) portion of the domain tended to be positively correlated with precipitation and negatively correlated with air temperature, while emissions from wetter and colder wetlands further north (permafrost) tended to be positively correlated with air temperature. Over the period 1960-2006, emissions increased by 20%, over 90% of which can be attributed to climate change, with summer air temperatures explaining the majority of the variance. We estimated future emissions in response to CMIP5 model projections under the RCP4.5 scenario via two methods: (1) the VIC model and (2) the temperature- and precipitation-dependent sensitivities computed from the historical simulation. The two methods yielded similar projections of emissions, with end-of-century emissions at 142% of present-day levels, accompanied by an expansion of the area of water-limited wetlands. Both the magnitude of the increase in emissions and the widespread drying of wetlands are corroborated by other recent process-based studies.

  10. The controls of methane emission from an Indian mangrove

    NASA Astrophysics Data System (ADS)

    Purvaja, R.; Ramesh, R.; Frenzel, P.

    2003-04-01

    Mangroves have been rated for a long time as a minor methane source, but recent reports have shown that polluted mangroves may emit substantial amounts of methane. In an Indian mangrove dominated by Avicennia marina we measured annual methane emission rates of 10 g methane/year, comparable to those from Northern wetlands. Methane emission from a freshwater-influenced area was higher, but lower from a stunted mangrove growing on a hypersaline soil, respectively. Methane emission was mediated by the pneumatophores of Avicennia. This was consistent with the methane concentration in the aerenchyma that decreased on average from 350 ppmv in the cable roots to 10 ppmv in the emergent part of the pneumatophores. The number of pneumatophores varied seasonally. During the monsoon floods less pneumatophores emerged from the water, reducing methane fluxes largely. Hence, CH4 emission was controlled via the pneumatophores by the water level.

  11. Toxic emission control systems for mixed waste storage tanks

    SciTech Connect

    Robinson, J.D. ); Hansen, G.E. )

    1993-02-01

    The use of emission control systems on mixed waste storage tanks is a critical issue as characterization and remediation of tanks becomes a leading priority at DOE sites. The current tank ventilation systems, where installed, are designed primarily for the control of radionuclides with no treatment systems incorporated for toxic emissions. Many of the tanks also lack ammonia treatment systems, although ammonia, due to its noxious odor, is controlled in some applications. The need for emission control systems has become apparent by the numerous occurrences of occupational employee exposure and the buildup of toxic and/or flammable materials in the vapor space of tanks. This paper will focus on two alternate systems for the control of toxic emissions, and will provide a discussion of the key issues which must be addressed for each system. The contents of this paper are the results of two efforts being performed by Engineering-Science, Inc., under the contract to Battelle Environmental Management Operations (EMO), for the Westinghouse Hanford Company. These efforts are for the study, design, fabrication, installation, and testing of new modular exhaust units for the 241-C-103 Tank and for several tanks which are candidates for the Rotary Mode Core Sampling (RMCS) characterization. If one exhaust system can be used in several applications, during high activity and personnel exposure periods, then a tremendous savings to the capital investment needs, the annual operating budget, and decontamination and decommissioning costs can be realized.

  12. Emissions, combustion dynamics, and control of a multiple swirl combustor

    NASA Astrophysics Data System (ADS)

    Li, Guoqiang

    To achieve single digit NOx emission from gas turbine combustors and prevent the combustion dynamics encountered in Lean Premixed Combustion, it is essential to understand the correlations among emission characteristics, combustion dynamics, and dynamics and characteristics of swirling flow field. The focus of this dissertation is to investigate the emission characteristics and combustion dynamics of multiple swirl dump combustors either in premixing or non-premixed combustion (e.g. Lean Direct Injection), and correlate these combustion characteristics (emissions, combustion instability and lean flammability) to the fluids dynamics (flow structures and its evolution). This study covers measurement of velocity flow field, temperature field, and combustion under effects of various parameters, including inlet flow Reynolds number, inlet air temperature, swirl configurations, downstream exhaust nozzle contraction ratios, length of mixing tube. These parameters are tested in both liquid and gaseous fuel combustions. Knowledge obtained through this comprehensive study is applied to passive and active controls for improving gas turbine combustion performance in the aid of novel sensor and actuator technologies. Emissions and combustion characteristics are shown closely related to the shape and size of central recirculation zone (CRZ), the mean and turbulence velocity and strain rate, and dynamics of large vortical structures. The passive controls, mostly geometry factors, affect the combustion characteristics and emissions through their influences on flow fields, and consequently temperature and radical fields. Air assist, which is used to adjust the momentum of fuel spray, is effective in reducing NOx and depress combustion oscillation without hurting LBO. Fuel distribution/split is also one important factor for achieving low NOx emission and control of combustion dynamics. The dynamics of combustion, including flame oscillations close to LBO and acoustic combustion instability, can be characterized by OH*/CH* radical oscillations and phase-locked chemiluminescence imaging. The periodic fluctuation of jet velocity and formation of large vortical structures within CRZ are responsible for combustion instability in multiple swirl combustors.

  13. Enhanced control of mercury emissions through modified speciation

    SciTech Connect

    Livengood, C.D.; Mendelsohn, M.H.

    1997-07-01

    In anticipation of possible regulations regarding mercury emissions, research efforts sponsored by DOE, EPRI, and others are investigating the risks posed by mercury emissions, improved techniques for measuring those emissions, and possible control measures. The focus in the control research is on techniques that can be used in conjunction with existing flue-gas-cleanup (FGC) systems in order to minimize additional capital costs and operational complexity. Argonne National Laboratory has supported the DOE Fossil Energy Program for over 15 years with research on advanced environmental control technologies. The emphasis in Argonne`s work has been on integrated systems that combine control of several pollutants. Specific topics have included spray drying for sulfur dioxide and particulate-matter control with high-sulfur coal, combined sulfur dioxide and nitrogen oxides control technologies, and techniques to enhance mercury control in existing FGC systems. The latter area has focused on low-cost dry sorbents for use with fabric filters or electrostatic precipitators and techniques for improving the capture of mercury in wet flue-gas desulfurization (FGD) systems. This paper presents results from recent work that has studied the effects of several oxidizing agents in combination with typical flue-gas species (e.g., nitrogen oxides and sulfur dioxide) on the oxidation of Hg{sup 0}.

  14. An adaptive controller for the administration of closed-circuit anesthesia during spontaneous and assisted ventilation.

    PubMed

    Sharma, A; Griffith, R L; Roy, R J

    1993-01-01

    Although reduced waste of expensive anesthetic gases is a strong incentive to use closed-circuit anesthesia, manual methods of performing closed-circuit anesthesia are labor intensive and thus not widely used. Automation of closed-circuit anesthesia delivery may reduce the work. A pressure-based adaptive controller was designed and tested on mongrel dogs to evaluate the feasibility of automating closed-circuit anesthesia using an accessory to an existing clinical anesthesia machine and a gas analyzer. The controller was found stable and responsive with good control of oxygen concentration and acceptable control of halothane end-tidal concentration. The response time for oxygen was 5.23 +/- 1.26 minutes, and that for halothane was 2.67 +/- 1.83 minutes. The average peak overshoot for halothane at the start of the experiment was 26.9%. This pressure controller differs from previously published closed-circuit anesthesia controllers that measure gas volume changes within a mechanical ventilator. A pressure-based controller is easily attached to a standard anesthesia machine and is compatible with modes of ventilation other than controlled mechanical ventilation. The controller used in this study is not designed for clinical use, but was developed to investigate the feasibility of pressure as a basis for gas volume control in closed-circuit anesthesia administration. PMID:8463802

  15. Improved control over spontaneously formed GaN nanowires in molecular beam epitaxy using a two-step growth process.

    PubMed

    Zettler, J K; Corfdir, P; Geelhaar, L; Riechert, H; Brandt, O; Fernndez-Garrido, S

    2015-11-01

    We investigate the influence of modified growth conditions during the spontaneous formation of GaN nanowires (NWs) on Si(111) in plasma-assisted molecular beam epitaxy. We find that a two-step growth approach, where the substrate temperature is increased during the nucleation stage, is an efficient method to gain control over the area coverage, average diameter, and coalescence degree of GaN NW ensembles. Furthermore, we also demonstrate that the growth conditions employed during the incubation time that precedes nanowire nucleation do not influence the properties of the final nanowire ensemble. Therefore, when growing GaN NWs at elevated temperatures or with low Ga/N ratios, the total growth time can be reduced significantly by using more favorable growth conditions for nanowire nucleation during the incubation time. PMID:26457772

  16. Improved control over spontaneously formed GaN nanowires in molecular beam epitaxy using a two-step growth process

    NASA Astrophysics Data System (ADS)

    Zettler, J. K.; Corfdir, P.; Geelhaar, L.; Riechert, H.; Brandt, O.; Ferndez-Garrido, S.

    2015-11-01

    We investigate the influence of modified growth conditions during the spontaneous formation of GaN nanowires (NWs) on Si(111) in plasma-assisted molecular beam epitaxy. We find that a two-step growth approach, where the substrate temperature is increased during the nucleation stage, is an efficient method to gain control over the area coverage, average diameter, and coalescence degree of GaN NW ensembles. Furthermore, we also demonstrate that the growth conditions employed during the incubation time that precedes nanowire nucleation do not influence the properties of the final nanowire ensemble. Therefore, when growing GaN NWs at elevated temperatures or with low Ga/N ratios, the total growth time can be reduced significantly by using more favorable growth conditions for nanowire nucleation during the incubation time.

  17. Stark interaction of identical particles with the vacuum electromagnetic field as quantum Poisson process suppressing collective spontaneous emission

    SciTech Connect

    Basharov, A. M.

    2011-07-15

    The effective Hamiltonian describing resonant interaction of an ensemble of identical quantum particles with a photon-free vacuum electromagnetic field has been obtained with allowance for terms of second order in the coupling constant (the Stark interaction) by means of the perturbation theory on the basis of the unitary transformation of the system quantum state. It has been shown that in the Markov approximation the effective Hamiltonian terms of first order in the coupling constant are represented by the quantum Wiener process, whereas terms of second order are expressed by the quantum Poisson process. During the course of the investigation, it was established that the Stark interaction played a significant role in the ensemble dynamics, thus influencing the collective spontaneous decay of the ensemble of an appreciably high number of identical particles. Fundamental effects have been discovered, i.e., the excitation conservation in a sufficiently dense ensemble of identical particles and superradiance suppression in the collective decaying process of an excited ensemble with a determined number of particles.

  18. SPRAY CHARGING AND TRAPPING SCRUBBER FOR FUGITIVE PARTICLE EMISSION CONTROL

    EPA Science Inventory

    The report gives results of a theoretical and experimental evaluation of the control of fugitive particle emissions (FPE) with a Spray Charging and Trapping (SCAT) Scrubber that uses an air curtain and/or jets to contain, convey, and divert the FPE into a charged spray scrubber. ...

  19. ASSESSMENT OF THE USE OF FUGITIVE EMISSION CONTROL DEVICES

    EPA Science Inventory

    The report compares the efficiencies and utility consumptions expected from three fugitive emission control techniques--building evacuation, charged fog sprays, and water sprays with additives--if they were applied in primary lead and copper smelters. Estimates are provided of th...

  20. Spontaneous Fission

    DOE R&D Accomplishments Database

    Segre, Emilio

    1950-11-22

    The first attempt to discover spontaneous fission in uranium was made by [Willard] Libby, who, however, failed to detect it on account of the smallness of effect. In 1940, [K. A.] Petrzhak and [G. N.] Flerov, using more sensitive methods, discovered spontaneous fission in uranium and gave some rough estimates of the spontaneous fission decay constant of this substance. Subsequently, extensive experimental work on the subject has been performed by several investigators and will be quoted in the various sections. [N.] Bohr and [A.] Wheeler have given a theory of the effect based on the usual ideas of penetration of potential barriers. On this project spontaneous fission has been studied for the past several years in an effort to obtain a complete picture of the phenomenon. For this purpose the spontaneous fission decay constants {lambda} have been measured for separated isotopes of the heavy elements wherever possible. Moreover, the number {nu} of neutrons emitted per fission has been measured wherever feasible, and other characteristics of the spontaneous fission process have been studied. This report summarizes the spontaneous fission work done at Los Alamos up to January 1, 1945. A chronological record of the work is contained in the Los Alamos monthly reports.

  1. Particulate Emissions from a Pre-Emissions Control Era Spark-Ignition Vehicle: A Historical Benchmark

    SciTech Connect

    John M.E. Storey; C. Scott Sluder; Douglas A. Blom; Erin Higinbotham

    2000-06-19

    This study examined the particulate emissions from a pre-emissions control era vehicle operated on both leaded and unleaded fuels for the purpose of establishing a historical benchmark. A pre-control vehicle was located that had been rebuilt with factory original parts to approximate an as-new vehicle prior to 1968. The vehicle had less than 20,000 miles on the rebuilt engine and exhaust. The vehicle underwent repeated FTP-75 tests to determine its regulated emissions, including particulate mass. Additionally, measurements of the particulate size distribution were made, as well as particulate lead concentration. These tests were conducted first with UTG96 certification fuel, followed by UTG96 doped with tetraethyl lead to approximate 1968 levels. Results of these tests, including transmission electron micrographs of individual particles from both the leaded and unleaded case are presented. The FTP composite PM emissions from this vehicle averaged 40.5 mg/mile using unleaded fuel. The results from the leaded fuel tests showed that the FTP composite PM emissions increased to an average of 139.5 mg/mile. Analysis of the particulate size distribution for both cases demonstrated that the mass-based size distribution of particles for this vehicle is heavily skewed towards the nano-particle range. The leaded-fuel tests showed a significant increase in mass concentration at the <0.1 micron size compared with the unleaded-fuel test case. The leaded-fuel tests produced lead emissions of nearly 0.04 g/mi, more than a 4-order-of-magnitude difference compared with unleaded-fuel results. Analysis of the size-fractionated PM samples showed that the lead PM emissions tended to be distributed in the 0.25 micron and smaller size range.

  2. Solar wind control of Jupiter's hectometric radio emission

    NASA Technical Reports Server (NTRS)

    Barrow, C. H.; Desch, M. D.

    1989-01-01

    Radio, plasma, and magnetic field data obtained by Voyager 1 and Voyager 2 were used to examine the manner in which the Jovian hectometric radio emission (HOM) is controlled by the solar wind. Using the method of superposed epochs, it was found that the higher energy HOM is correlated with the IMF as well as with the solar wind density and pressure. However, unlike the Io-independent decametric radio emission (Non-Io DAM), the HOM displayed no correlation with the solar wind velocity, although this radio component appear to be also influenced by the IMF. The results suggest separate HOM amd Non-Io DAM sources.

  3. Air emission control equipment - the new challenge for equpiment suppliers

    SciTech Connect

    Lobb, F.H.

    1997-12-31

    The combination of Title V, the CAM Rule and the Credible Evidence Rule demand industrial sites view the selection and operation of emission control devices in a whole new light. No longer can users see these devices as detached end of pipe pieces of equipment essentially purchased off lowest bid. These regulatory changes force plants to fully integrate the operation of these devices into their process control systems and instrumentation. And this is specifically EPA`s stated intent. EPA believes that by forcing sites to exercise the same knowledge and attention to air emissions that they do to operate their production processes, emissions will undergo a natural reduction across the country. Process and operational data that historically has been the sole province of sites becomes public. And compliance with state defined requirements must be demonstrated essentially continuously. This paper explores the new approach to compliance and provides insight through specific field examples/installations of emission control equipment. The author seeks to promote understanding through discussion of these significant regulatory changes.

  4. Biofiltration: An innovative air pollution control technology for VOC emissions

    SciTech Connect

    Leson, G. ); Winer, A.M. )

    1991-08-01

    Biofiltration is a relatively recent air pollution control (APC) technology in which off-gases containing biodegradable volatile organic compounds (VOC) or inorganic air toxics are vented through a biologically active material. This technology has been successfully applied in Germany and The Netherlands in many full-scale applications to control odors, VOC and air toxic emissions from a wide range of industrial and public sector sources. Control efficiencies of more than 90 percent have been achieved for many common air pollutants. Due to lower operating costs, biofiltration can provide significant economic advantages over other APC technologies if applied to off-gases that contain readily biodegradable pollutants in low concentrations. Environmental benefits include low energy requirements and the avoidance of cross media transfer of pollutants. This paper reviews the history and current status of biofiltration, outlines its underlying scientific and engineering principles, and discusses the applicability of biofilters for a wide range of specific emission sources.

  5. Control of air pollution emissions from municipal waste combustors

    SciTech Connect

    Kolgroe, J.D.; Licata, A.

    1996-09-01

    The November 1990 Clear Air Act Amendments (CAAAs) directed EPA to establish municipal waste combustor (MWC) emissions limits for particulate matter, opacity, hydrogen chloride, sulfur dioxide, nitrogen oxides, carbon monoxide, dioxins, dibenzofurans, cadmium, lead, and mercury. Revised MWC air pollution regulations were subsequently proposed by EPA on September 20, 1994, and promulgated on December 19, 1995. The MWC emission limits were based on the application of maximum achievable control technology (MACT). This paper provides a brief overview of MWC technologies, a summary of EPA`s revised air pollution rules for MWCs, a review of current knowledge concerning formation and control of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, and a discussion of the behavior and control of mercury in MWC flue gases. 56 refs., 11 figs., 3 tabs.

  6. Peritonitis - spontaneous

    MedlinePLUS

    ... alcohol use Chronic viral hepatitis ( hepatitis B or hepatitis C ) Other diseases that lead to cirrhosis Spontaneous peritonitis ... dehydration . You may need to stay in the hospital so health care ... out conditions such as such as appendicitis and diverticulitis .

  7. Control of volatile organic compound emissions from batch processes. Alternative control techniques information document. Final report

    SciTech Connect

    Not Available

    1994-02-01

    The purpose of this document is to provide information on alternative control techniques for volatile organic compound (VOC) emissions from batch operations. Although the control techniques information applies to batch processing in all industries, the document focuses primarily on batch processes in the following six industries: plastic materials and resins (described by Standard Industrial Classification (SIC) Code 2821), pharmaceuticals (SIC 2833 and 2834), gum and wood chemicals (SIC 2861), cyclic crudes and intermediates (SIC 2865), industrial organic chemicals (2869), and agricultural chemicals (SIC 2879). The document contains information on emissions, controls, control options, and costs that States can use in developing rules based on reasonably available control technology.

  8. Spontaneous pre-stimulus fluctuations in the activity of right fronto-parietal areas influence inhibitory control performance

    PubMed Central

    Chavan, Camille F.; Manuel, Aurelie L.; Mouthon, Michael; Spierer, Lucas

    2013-01-01

    Inhibitory control refers to the ability to suppress planned or ongoing cognitive or motor processes. Electrophysiological indices of inhibitory control failure have been found to manifest even before the presentation of the stimuli triggering the inhibition, suggesting that pre-stimulus brain-states modulate inhibition performance. However, previous electrophysiological investigations on the state-dependency of inhibitory control were based on averaged event-related potentials (ERPs), a method eliminating the variability in the ongoing brain activity not time-locked to the event of interest. These studies thus left unresolved whether spontaneous variations in the brain-state immediately preceding unpredictable inhibition-triggering stimuli also influence inhibitory control performance. To address this question, we applied single-trial EEG topographic analyses on the time interval immediately preceding NoGo stimuli in conditions where the responses to NoGo trials were correctly inhibited [correct rejection (CR)] vs. committed [false alarms (FAs)] during an auditory spatial Go/NoGo task. We found a specific configuration of the EEG voltage field manifesting more frequently before correctly inhibited responses to NoGo stimuli than before FAs. There was no evidence for an EEG topography occurring more frequently before FAs than before CR. The visualization of distributed electrical source estimations of the EEG topography preceding successful response inhibition suggested that it resulted from the activity of a right fronto-parietal brain network. Our results suggest that the fluctuations in the ongoing brain activity immediately preceding stimulus presentation contribute to the behavioral outcomes during an inhibitory control task. Our results further suggest that the state-dependency of sensory-cognitive processing might not only concern perceptual processes, but also high-order, top-down inhibitory control mechanisms. PMID:23761747

  9. Control of mercury emissions from coal-fired boilers

    SciTech Connect

    Huang, H.S.; Livengood, C.D.

    1992-01-01

    This project at Argonne is designed to investigate new concepts leading to advanced control technologies for fossil-energy systems. The objective of this new task on air toxics control is to develop new or improved, cost-effective control technology for the abatement of emissions of hazardous air pollutants (HAPs) from fossil-fuel combustion plants and to evaluate the possible effects of any captured species on waste disposal. The HAPs to be investigated initially in this task include mercury and arsenic compounds.

  10. Control of mercury emissions from coal-fired boilers

    SciTech Connect

    Huang, H.S.; Livengood, C.D.

    1992-09-01

    This project at Argonne is designed to investigate new concepts leading to advanced control technologies for fossil-energy systems. The objective of this new task on air toxics control is to develop new or improved, cost-effective control technology for the abatement of emissions of hazardous air pollutants (HAPs) from fossil-fuel combustion plants and to evaluate the possible effects of any captured species on waste disposal. The HAPs to be investigated initially in this task include mercury and arsenic compounds.

  11. Chlorine vs. dioxins -- Control methods to minimize emissions

    SciTech Connect

    Santoleri, J.J.

    1996-09-01

    With the enactment of the Boiler and Industrial Furnace (BIF) regulations in August, 1991, hazardous waste combustors were required to sample and demonstrate compliance with chlorine (Cl{sub 2}) emissions. The Resource Conservation and Recovery Act of 1976 required analysis and control of hydrogen chloride (HCl) emissions with no requirements for chlorine emissions from combustion systems burning chlorinated organic and organic waste streams. Prior to the BIF regulations, the levels of chlorine emissions from waste combustion systems had not been measured or their impacts on emissions known. Recent studies have demonstrated that the formation of precursors that create the Products of Incomplete Combustion (PICs) such as PCDD/PCDFs is caused by the free Cl{sub 2}, more so than the HCl. The effect of ash deposition on metallic surfaces such as boiler tubes, heat exchange surfaces, pollution control devices, ductwork and bag filter supports cause cells of activity between the HCl, Cl{sub 2}, iron, and copper which again serve as catalysts for the formation of PCDD/PCDFs. The effect of chlorine concentration in the flue gases, the temperatures of the surfaces allowing the reactions to take place, and the time available for the reaction will be discussed in relationship to the PIC emission. HCl is easily absorbed in water, whether in a quench tower or spray dryer. Chlorine is much more difficult to neutralize than HCl and requires a basic solution of caustic or lime. Therefore, Cl{sub 2} often persists in those APC systems that are designed for the 99% removal of HCl only.

  12. A quantum dot single-photon source with on-the-fly all-optical polarization control and timed emission

    PubMed Central

    Heinze, Dirk; Breddermann, Dominik; Zrenner, Artur; Schumacher, Stefan

    2015-01-01

    Sources of single photons are key elements for applications in quantum information science. Among the different sources available, semiconductor quantum dots excel with their integrability in semiconductor on-chip solutions and the potential that photon emission can be triggered on demand. Usually, the photon is emitted from a single-exciton ground state. Polarization of the photon and time of emission are either probabilistic or pre-determined by electronic properties of the system. Here, we study the direct two-photon emission from the biexciton. The two-photon emission is enabled by a laser pulse driving the system into a virtual state inside the band gap. From this intermediate state, the single photon of interest is then spontaneously emitted. We show that emission through this higher-order transition provides a versatile approach to generate a single photon. Through the driving laser pulse, polarization state, frequency and emission time of the photon can be controlled on-the-fly. PMID:26436776

  13. Spontaneous and electric field–controlled front–rear polarization of human keratinocytes

    PubMed Central

    Saltukoglu, Deniz; Grünewald, Julian; Strohmeyer, Nico; Bensch, Robert; Ulbrich, Maximilian H.; Ronneberger, Olaf; Simons, Matias

    2015-01-01

    It has long been known that electrical fields (EFs) are able to influence the direction of migrating cells, a process commonly referred to as electrotaxis or galvanotaxis. Most studies have focused on migrating cells equipped with an existing polarity before EF application, making it difficult to delineate EF-specific pathways. Here we study the initial events in front–rear organization of spreading keratinocytes to dissect the molecular requirements for random and EF-controlled polarization. We find that Arp2/3-dependent protrusive forces and Rac1/Cdc42 activity were generally required for both forms of polarization but were dispensable for controlling the direction of EF-controlled polarization. By contrast, we found a crucial role for extracellular pH as well as G protein coupled–receptor (GPCR) or purinergic signaling in the control of directionality. The normal direction of polarization toward the cathode was reverted by lowering extracellular pH. Polarization toward the anode was also seen at neutral pH when GPCR or purinergic signaling was inhibited. However, the stepwise increase of extracellular pH in this scenario led to restoration of cathodal polarization. Overall our work puts forward a model in which the EF uses distinct polarization pathways. The cathodal pathway involves GPCR/purinergic signaling and is dominant over the anodal pathway at neutral pH. PMID:26424799

  14. Spontaneous and electric field-controlled front-rear polarization of human keratinocytes.

    PubMed

    Saltukoglu, Deniz; Grnewald, Julian; Strohmeyer, Nico; Bensch, Robert; Ulbrich, Maximilian H; Ronneberger, Olaf; Simons, Matias

    2015-12-01

    It has long been known that electrical fields (EFs) are able to influence the direction of migrating cells, a process commonly referred to as electrotaxis or galvanotaxis. Most studies have focused on migrating cells equipped with an existing polarity before EF application, making it difficult to delineate EF-specific pathways. Here we study the initial events in front-rear organization of spreading keratinocytes to dissect the molecular requirements for random and EF-controlled polarization. We find that Arp2/3-dependent protrusive forces and Rac1/Cdc42 activity were generally required for both forms of polarization but were dispensable for controlling the direction of EF-controlled polarization. By contrast, we found a crucial role for extracellular pH as well as G protein coupled-receptor (GPCR) or purinergic signaling in the control of directionality. The normal direction of polarization toward the cathode was reverted by lowering extracellular pH. Polarization toward the anode was also seen at neutral pH when GPCR or purinergic signaling was inhibited. However, the stepwise increase of extracellular pH in this scenario led to restoration of cathodal polarization. Overall our work puts forward a model in which the EF uses distinct polarization pathways. The cathodal pathway involves GPCR/purinergic signaling and is dominant over the anodal pathway at neutral pH. PMID:26424799

  15. Failing to Forget: Prospective Memory Commission Errors Can Result from Spontaneous Retrieval and Impaired Executive Control

    ERIC Educational Resources Information Center

    Scullin, Michael K.; Bugg, Julie M.

    2013-01-01

    Prospective memory (PM) research typically examines the ability to remember to execute delayed intentions but often ignores the ability to forget finished intentions. We had participants perform (or not perform; control group) a PM task and then instructed them that the PM task was finished. We later (re)presented the PM cue. Approximately 25% of

  16. LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL

    SciTech Connect

    Don Augenstein

    1999-01-11

    ''Conventional'' waste landfills emit methane, a potent greenhouse gas, in quantities such that landfill methane is a major factor in global climate change. Controlled landfilling is a novel approach to manage landfills for rapid completion of total gas generation, maximizing gas capture and minimizing emissions of methane to the atmosphere. With controlled landfilling, methane generation is accelerated and brought to much earlier completion by improving conditions for biological processes (principally moisture levels) in the landfill. Gas recovery efficiency approaches 100% through use of surface membrane cover over porous gas recovery layers operated at slight vacuum. A field demonstration project's results at the Yolo County Central Landfill near Davis, California are, to date, highly encouraging. Two major controlled landfilling benefits would be the reduction of landfill methane emissions to minuscule levels, and the recovery of greater amounts of landfill methane energy in much shorter times than with conventional landfill practice. With the large amount of US landfill methane generated, and greenhouse potency of methane, better landfill methane control can play a substantial role in reduction of US greenhouse gas emissions.

  17. Venturi/vortex technology for controlling chromium electroplating emissions

    SciTech Connect

    Hay, K.J.; Northrup, J.; Heck, S.R.

    1997-12-31

    A new technology has been developed to control air emissions from hexavalent chromium electroplating tanks. The venturi/vortex scrubber uses a patented drain assembly to pull plating solution, air with toxic particulates above the solution, and unpopped bubbles of generated gases down with a gravity generated vortex effect. The recirculated plating solution acts as the scrubbing liquid and air agitation is eliminated. Separated gases are passed through a condenser/filter to remove any remaining fumes. The device is almost entirely constructed of CPVC. This device offers several advantages over conventional end-of-pipe systems including significantly lower cost, no wastewater, no extensive ventilation system, and emissions are recycled. The system can be is easily retrofitted to existing tanks, however, a loose fitting tank lid is recommended. A pilot demonstration has been performed at Benet Laboratory, Watervliet, NY (US Army) with a 1,500 gallon chromic acid electroplating tank and 1,500 Amps of applied current. Overall chromium emissions results were 0.00002 mg/Amp-hr, surpassing the stringent California State requirement of 0.006 mg/Amp-hr. Emission prevention by capturing unpopped bubbles is the method in which this system reduces the most emissions. The system met current ambient worker safety standards. Two major improvements are recommended: an increase in gas flow rate through the system and a solution to the system`s sensitivity to the plating solution level.

  18. Control of Several Emissions during Olive Pomace Thermal Degradation

    PubMed Central

    Miranda, Teresa; Nogales, Sergio; Román, Silvia; Montero, Irene; Arranz, José Ignacio; Sepúlveda, Francisco José

    2014-01-01

    Biomass plays an important role as an energy source, being an interesting alternative to fossil fuels due to its environment-friendly and sustainable characteristics. However, due to the exposure of customers to emissions during biomass heating, evolved pollutants should be taken into account and controlled. Changing raw materials or mixing them with another less pollutant biomass could be a suitable step to reduce pollution. This work studied the thermal behaviour of olive pomace, pyrenean oak and their blends under combustion using thermogravimetric analysis. It was possible to monitor the emissions released during the process by coupling mass spectrometry analysis. The experiments were carried out under non-isothermal conditions at the temperature range 25–750 °C and a heating rate of 20 °C·min−1. The following species were analysed: aromatic compounds (benzene and toluene), sulphur emissions (sulphur dioxide), 1,4-dioxin, hydrochloric acid, carbon dioxide and nitrogen oxides. The results indicated that pollutants were mainly evolved in two different stages, which are related to the thermal degradation steps. Thus, depending on the pollutant and raw material composition, different emission profiles were observed. Furthermore, intensity of the emission profiles was related, in some cases, to the composition of the precursor. PMID:25314298

  19. Control of several emissions during olive pomace thermal degradation.

    PubMed

    Miranda, Teresa; Nogales, Sergio; Romn, Silvia; Montero, Irene; Arranz, Jos Ignacio; Seplveda, Francisco Jos

    2014-01-01

    Biomass plays an important role as an energy source, being an interesting alternative to fossil fuels due to its environment-friendly and sustainable characteristics. However, due to the exposure of customers to emissions during biomass heating, evolved pollutants should be taken into account and controlled. Changing raw materials or mixing them with another less pollutant biomass could be a suitable step to reduce pollution. This work studied the thermal behaviour of olive pomace, pyrenean oak and their blends under combustion using thermogravimetric analysis. It was possible to monitor the emissions released during the process by coupling mass spectrometry analysis. The experiments were carried out under non-isothermal conditions at the temperature range 25-750 C and a heating rate of 20 Cmin?. The following species were analysed: aromatic compounds (benzene and toluene), sulphur emissions (sulphur dioxide), 1,4-dioxin, hydrochloric acid, carbon dioxide and nitrogen oxides. The results indicated that pollutants were mainly evolved in two different stages, which are related to the thermal degradation steps. Thus, depending on the pollutant and raw material composition, different emission profiles were observed. Furthermore, intensity of the emission profiles was related, in some cases, to the composition of the precursor. PMID:25314298

  20. Dynamic Control of Thermal Emission with Plasmonically Active Graphene Metasurfaces

    NASA Astrophysics Data System (ADS)

    Brar, Victor; Sherrott, Michelle; Jang, Min; Kim, Seyoon; Kim, Laura; Lopez, Josue; Choi, Mansoo; Sweatlock, Luke; Atwater, Harry

    2015-03-01

    Thermal emission is typically viewed to be broadband, unpolarized and isotropic, with a spectral profile and intensity that depend on the emissivity of the material, and that vary only with changes in temperature. In this talk we demonstrate that the intensity, polarization and spectrum of thermal emission at constant temperature can be dynamically controlled through electrostatic gating of plasmonic graphene resonators on a heated SiNx substrate. We show that the plasmonic resonances in graphene act as antenna that to out-couple the thermal energy of substrate phonons and graphene electrons to create narrow, mid-infrared spectral features in the thermal emission profile. By varying the gate voltage and resonator width, we show that these features can be effectively turned on and off at kHz rates, and tuned across a broad frequency range. Our measurements show that at 7um the emissivity of the surface can be varied by 0.02, and that the emitted radiation is polarized, with a modulated power density of 0.02W/m2 over 100cm-1 of bandwidth.

  1. Ozone trends in Atlanta, Georgia - Have emission controls been effective?

    NASA Technical Reports Server (NTRS)

    Lindsay, Ronald W.; Richardson, Jennifer L.; Chameldes, William L.

    1989-01-01

    Nine years of summertime ozone data from the Atlanta metropolitan area are analyzed and compared to local emissions of volatile organic carbon and nitrogen oxides. Trends from 1979 to 1987 were studied for the number of days per year ozone exceeded the NAAQS standard, the second-highest ozone level observed per year, and the first quartile summertime average ozone observed, as well as the mean difference between the ozone level observed downwind and upwind of the city. Because this last parameter is sensitive to chemical factors but relatively insensitive to the number of days each year with meteorological conditions conducive to ozone formation, its trend may be best suited for determining how effective emission controls have been in reducing O3 in the Atlanta area. In spite of the fact that sizeable reductions have been claimed for volatile organic carbon emissions over the past several years, the data give no indication that ozone levels have decreased and in fact, imply that summertime ozone production may have increased. The results imply that either emissions have not decreased as much as has been claimed or that ozone is not sensitive to anthropogenic volatile organic carbon emissions.

  2. Emissions from premixed charge compression ignition (PCCI) combustion and affect on emission control devices

    SciTech Connect

    Parks, II, James E; Kass, Michael D; Huff, Shean P; Barone, Teresa L; Lewis Sr, Samuel Arthur; Prikhodko, Vitaly Y; Storey, John Morse

    2010-01-01

    A light-duty diesel engine has been operated in advanced combustion modes known generally as premixed charge compression ignition (PCCI). The emissions have been characterized for several load and speed combinations. Fewer NO{sub x} and particulate matter (PM) emissions are produced by PCCI, but higher CO and hydrocarbon (HC) emissions result. In addition, the nature of the PM differs from conventional combustion; the PM is smaller and has a much higher soluble organic fraction (SOF) content (68% vs. 30% for conventional combustion). Three catalyst technologies were studied to determine the affects of HECC on catalyst performance; the technologies were a lean NO{sub x} trap (LNT), diesel oxidation catalyst (DOC), and diesel particulate filter (DPF). The LNT benefited greatly from the reduced NO{sub x} emissions associated with PCCI. NO{sub x} capacity requirements are reduced as well as overall tailpipe NO{sub x} levels particularly at low load and temperature conditions where regeneration of the LNT is difficult. The DOC performance requirements for PCCI are more stringent due to the higher CO and HC emissions; however, the DOC was effective at controlling the higher CO and HC emissions at conditions above the light-off temperature. Below light-off, CO and HC emissions are problematic. The study of DPF technology focused on the fuel penalties associated with DPF regeneration or 'desoot' due to the different PM loading rates from PCCI vs. conventional combustion. Less frequent desoot events were required from the lower PM from PCCI and, when used in conjunction with an LNT, the lower PM from less frequent LNT regeneration. The lower desoot frequency leads a {approx}3% fuel penalty for a mixture of PCCI and conventional loads vs. {approx}4% for conventional only combustion.

  3. The effects of energy paths and emission controls and standards on future trends in China's emissions of primary air pollutants

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Zhang, J.; Nielsen, C. P.

    2014-09-01

    To examine the efficacy of China's actions to control atmospheric pollution, three levels of growth of energy consumption and three levels of implementation of emission controls are estimated, generating a total of nine combined activity-emission control scenarios that are then used to estimate trends of national emissions of primary air pollutants through 2030. The emission control strategies are expected to have more effects than the energy paths on the future emission trends for all the concerned pollutants. As recently promulgated national action plans of air pollution prevention and control (NAPAPPC) are implemented, China's anthropogenic pollutant emissions should decline. For example, the emissions of SO2, NOx, total suspended particles (TSP), PM10, and PM2.5 are estimated to decline 7, 20, 41, 34, and 31% from 2010 to 2030, respectively, in the "best guess" scenario that includes national commitment of energy saving policy and implementation of NAPAPPC. Should the issued/proposed emission standards be fully achieved, a less likely scenario, annual emissions would be further reduced, ranging from 17 (for primary PM2.5) to 29% (for NOx) declines in 2015, and the analogue numbers would be 12 and 24% in 2030. The uncertainties of emission projections result mainly from the uncertain operational conditions of swiftly proliferating air pollutant control devices and lack of detailed information about emission control plans by region. The predicted emission trends by sector and chemical species raise concerns about current pollution control strategies: the potential for emissions abatement in key sectors may be declining due to the near saturation of emission control devices use; risks of ecosystem acidification could rise because emissions of alkaline base cations may be declining faster than those of SO2; and radiative forcing could rise because emissions of positive-forcing carbonaceous aerosols may decline more slowly than those of SO2 emissions and thereby concentrations of negative-forcing sulfate particles. Expanded control of emissions of fine particles and carbonaceous aerosols from small industrial and residential sources is recommended, and a more comprehensive emission control strategy targeting a wider range of pollutants (volatile organic compounds, NH3 and CO, etc.) and taking account of more diverse environmental impacts is also urgently needed.

  4. Revisiting factors controlling methane emissions from high-Arctic tundra

    NASA Astrophysics Data System (ADS)

    Mastepanov, M.; Sigsgaard, C.; Tagesson, T.; Strm, L.; Tamstorf, M. P.; Lund, M.; Christensen, T. R.

    2013-07-01

    The northern latitudes are experiencing disproportionate warming relative to the mid-latitudes, and there is growing concern about feedbacks between this warming and methane production and release from high-latitude soils. Studies of methane emissions carried out in the Arctic, particularly those with measurements made outside the growing season, are underrepresented in the literature. Here we present results of 5 yr (2006-2010) of automatic chamber measurements at a high-Arctic location in Zackenberg, NE Greenland, covering both the growing seasons and two months of the following freeze-in periods. The measurements show clear seasonal dynamics in methane emission. The start of the growing season and the increase in CH4 fluxes were strongly related to the date of snowmelt. Within each particular growing season, CH4 fluxes were highly correlated with the soil temperature (R2 > 0.75), which is probably explained by high seasonality of both variables, and weakly correlated with the water table. The greatest variability in fluxes between the study years was observed during the first part of the growing season. Somewhat surprisingly, this variability could not be explained by commonly known factors controlling methane emission, i.e. temperature and water table position. Late in the growing season CH4 emissions were found to be very similar between the study years (except the extremely dry 2010) despite large differences in climatic factors (temperature and water table). Late-season bursts of CH4 coinciding with soil freezing in the autumn were observed during at least three years. The cumulative emission during the freeze-in CH4 bursts was comparable in size with the growing season emission for the year 2007, and about one third of the growing season emissions for the years 2009 and 2010. In all three cases the CH4 burst was accompanied by a corresponding episodic increase in CO2 emission, which can compose a significant contribution to the annual CO2 flux budget. The most probable mechanism of the late-season CH4 and CO2 bursts is physical release of gases accumulated in the soil during the growing season. In this study we discuss possible links between growing season and autumn fluxes. Multiannual dynamics of the subsurface CH4 storage pool are hypothesized to be such a link and an important driver of intearannual variations in the fluxes, capable of overruling the conventionally known short-term control factors (temperature and water table). Our findings suggest the importance of multiyear studies with a continued focus on shoulder seasons in Arctic ecosystems.

  5. Controlling automotive exhaust emissions: successes and underlying science.

    PubMed

    Twigg, Martyn V

    2005-04-15

    Photochemical reactions of vehicle exhaust pollutants were responsible for photochemical smog in many cities during the 1960s and 1970s. Engine improvements helped, but additional measures were needed to achieve legislated emissions levels. First oxidation catalysts lowered hydrocarbon and carbon monoxide, and later nitrogen oxides were reduced to nitrogen in a two-stage process. By the 1980s, exhaust gas could be kept stoichiometric and hydrocarbons, carbon monoxide and nitrogen oxides were simultaneously converted over a single 'three-way catalyst'. Today, advanced three-way catalyst systems emissions are exceptionally low. NOx control from lean-burn engines demands an additional approach because NO cannot be dissociated under lean conditions. Current lean-burn gasoline engine NOx control involves forming a nitrate phase and periodically enriching the exhaust to reduce it to nitrogen, and this is being modified for use on diesel engines. Selective catalytic reduction with ammonia is an alternative that can be very efficient, but it requires ammonia or a compound from which it can be obtained. Diesel engines produce particulate matter, and, because of health concerns, filtration processes are being introduced to control these emissions. On heavy duty diesel engines the exhaust gas temperature is high enough for NO in the exhaust to be oxidised over a catalyst to NO2 that smoothly oxidises particulate material (PM) in the filter. Passenger cars operate at lower temperatures, and it is necessary to periodically burn the PM in air at high temperatures. PMID:15901550

  6. Side stream separator for boiler particulate emission control

    SciTech Connect

    Skiven, D.A.; Sortor, C.J.; Tessier, R.J.

    1982-02-09

    A device is disclosed for controlling the particulate emission from coal-fired boilers. A cyclone type primary separator between the boiler and the stack and a bag filter is coupled in side stream relation to the cyclone separator such as to shunt and departiculatize up to about 20% of the gas stream entering the cyclone. The shunted gas is drawn from below the tube sheet of the cyclone separator, filtered through the bags and returned to the stack. Means are provided to control the temperature of the shunted gas within defined limits corresponding to the acid dew point of the gas and the thermal degradation temperature of the filter media.

  7. Enhancement in the excitonic spontaneous emission rates for Si nanocrystal multi-layers covered with thin films of Au, Ag, and Al.

    PubMed

    Estrin, Y; Rich, D H; Rozenfeld, N; Arad-Vosk, N; Ron, A; Sa'ar, A

    2015-10-30

    The enhancement in the spontaneous emission rate (SER) for Ag, Au, and Al films on multilayer Si nanocrystals (SiNCs) was probed with time-resolved cathodoluminescence (CL). The SiNCs were grown on Si(100) using plasma enhanced chemical vapor deposition. Electron-hole pairs were generated in the metal-covered SiNCs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures that are opaque to laser or light excitation. Spatially, spectrally, and temporally resolved CL was used to measure the excitonic lifetime of the SiNCs in metal-covered and bare regions of the same samples. The observed enhancement in the SER for the metal-covered SiNCs, relative to the SER for the bare sample, is attributed to a coupling of the SiNC excitons with surface plasmon polaritons (SPPs) of the thin metal films. A maximum SER enhancement of ?2.0, 1.4 and 1.2 was observed for the Ag, Au, and Al films, respectively, at a temperature of 55 K. The three chosen plasmonic metals of Ag, Au, and Al facilitate an interesting comparison of the exciton-SPP coupling for metal films that exhibit varying differences between the surface plasmon energy, ?(sp), and the SiNC excitonic emission energy. A modeling of the temperature dependence of the Purcell enhancement factor, Fp, was performed and included the temperature dependence of the dielectric properties of the metals. PMID:26436289

  8. Enhancement in the excitonic spontaneous emission rates for Si nanocrystal multi-layers covered with thin films of Au, Ag, and Al

    NASA Astrophysics Data System (ADS)

    Estrin, Y.; Rich, D. H.; Rozenfeld, N.; Arad-Vosk, N.; Ron, A.; Sa'ar, A.

    2015-10-01

    The enhancement in the spontaneous emission rate (SER) for Ag, Au, and Al films on multilayer Si nanocrystals (SiNCs) was probed with time-resolved cathodoluminescence (CL). The SiNCs were grown on Si(100) using plasma enhanced chemical vapor deposition. Electron-hole pairs were generated in the metal-covered SiNCs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures that are opaque to laser or light excitation. Spatially, spectrally, and temporally resolved CL was used to measure the excitonic lifetime of the SiNCs in metal-covered and bare regions of the same samples. The observed enhancement in the SER for the metal-covered SiNCs, relative to the SER for the bare sample, is attributed to a coupling of the SiNC excitons with surface plasmon polaritons (SPPs) of the thin metal films. A maximum SER enhancement of ˜2.0, 1.4 and 1.2 was observed for the Ag, Au, and Al films, respectively, at a temperature of 55 K. The three chosen plasmonic metals of Ag, Au, and Al facilitate an interesting comparison of the exciton-SPP coupling for metal films that exhibit varying differences between the surface plasmon energy, ωsp, and the SiNC excitonic emission energy. A modeling of the temperature dependence of the Purcell enhancement factor, Fp, was performed and included the temperature dependence of the dielectric properties of the metals.

  9. Solution processable 2-(trityloxy)ethyl and tert-butyl group containing amorphous molecular glasses of pyranylidene derivatives with light-emitting and amplified spontaneous emission properties

    NASA Astrophysics Data System (ADS)

    Zarins, Elmars; Vembris, Aivars; Misina, Elina; Narels, Martins; Grzibovskis, Raitis; Kokars, Valdis

    2015-11-01

    Small organic molecules with incorporated 4H-pyran-4-ylidene (pyranylidene) fragment as the ?-conjugation system which bonds the electron acceptor fragment (A) with electron donor part (D) in the molecule - also well known as derivatives of 4-(dicyano-methylene)-2-methyl-6-[p-(dimethylamino)styryl]-4H-pyran (DCM) laser dye-have attracted considerable attention of scientists as potential new generation materials for organic photonics and molecular electronics due to their low-cost fabrication possibility, flexibility and low-weight. Six glassy derivatives of 4H-pyran-4-ylidene (pyranylidene) with attached bulky 2-(trityloxy)ethyl and tert-butyl groups are described in this report. Almost all of the synthesized compounds form good optical quality transparent amorphous films from volatile organic solvents and could be obtained in good yields up to 75%. Their light emission in solution and thin solid films is in the range of 600-700 nm, they are thermally stable and show glass transition in the range of 108-158 C. The amplified spontaneous emission threshold values of the neat films of the glassy pyranylidene derivatives vary from 155 to 450 ?J/cm2 and their HOMO and LUMO energy levels are between of those of tris(8-hydroxy quinolinato) aluminum (Alq3). The photoluminescence quantum yields of the glassy compounds are in the range from 1% to about 7.7% and their electroluminescence properties have been investigated. Therefore, glassy pyranylidene derivatives could be a very potential low-cost solution processable materials for Alq3 hosted light-amplification and light-emitting application studies.

  10. THE IMPACT OF PARTICULATE EMISSIONS CONTROL ON THE CONTROL OF OTHER MWC AIR EMISSIONS

    EPA Science Inventory

    On December 20, 1989, the Environmental Protection Agency (EPA) proposed revised new source performance standards for new municipal waste combustion (MWC) units and guidelines for existing sources. The proposed national regulations require tighter particulate matter control and a...

  11. Effects of macro-bending on 1500-nm amplified spontaneous emission, gain, and noise figure of erbium-gallium co-doped fiber

    NASA Astrophysics Data System (ADS)

    Jian, Leong Chia; Abdul Rashid, Hairul Azhar; Mokhtar, Mohd Ridzuan

    2015-12-01

    The relationships among macro-bending loss, power of the 1500-nm amplified spontaneous emission (ASE), gain, and noise figure of an erbium-gallium co-doped silica fiber amplifier are investigated and explained. The dependence of macro-bending loss on different bending radii is examined. Using different fiber lengths and bending radii, the effects of macro-bending on ASE, gain, and noise figure are analyzed in comparison to an unbent fiber. The ASE power changes because macro-bending alters the number of Er3+ ions in the I4 level that decay to the I4 level emitting photons of shorter and longer wavelengths. The trade-off relationship that exists between the change in the ASE power and signal loss, where both result from macro-bending, explains the gain change. Fiber length also affects the changes in the ASE power and gain. Noise figure in the longer-wavelength region increases. In the shorter-wavelength region, for a long fiber, the noise figure improves only slightly. For a short fiber, it worsens due to gain decrement. The findings from this study explain the reason for gain improvement upon suppressing either a competing or a noncompeting ASE via filters or macro-bending in other rare-earth-doped fibers.

  12. Self-assembly, highly modified spontaneous emission and energy transfer properties of LaPO4:Ce3+, Tb3+ inverse opals.

    PubMed

    Zhu, Yongsheng; Sun, Zhipeng; Yin, Ze; Song, Hongwei; Xu, Wen; Wang, Yunfeng; Zhang, Ligong; Zhang, Hanzhuang

    2013-06-14

    The modification of photonic crystals (PCs) on photoluminescence of rare earth (RE) ions has attracted considerable interest, however, the modification of PCs on energy transfer (ET) processes of two separate RE centers has not been investigated yet. In this paper, three-dimensional Ce(3+), Tb(3+)-codoped LaPO4 inverse opal PCs (IOPCs) were fabricated by the PMMA colloidal template method. The modification of the photonic stop band (PSB) on emission spectra and the dynamics of the 5d-4f transition of Ce(3+) and the 4f-4f transition of Tb(3+) ions were systematically studied. It is interesting to observe that the spontaneous decay rates (SDR) of (5)D4-(7)F5 in the IOPCs were suppressed as highly as 173% in contrast to the reference ground powder samples (REF) due to the modification of the effective refractive index (n(eff)). The energy transfer (ET) rate of Ce(3+) to Tb(3+) did not change in the IOPCs, however, the energy migration rate among Tb(3+) ions was largely restrained. It is also significant to observe that, in the IOPCs, the temperature quenching and radiation trapping of photoluminescence were greatly suppressed due to the periodic empty cavity structure of IOPCs, which is significant for high-power light sources and laser devices. PMID:23571776

  13. Air-Stable Surface-Passivated Perovskite Quantum Dots for Ultra-Robust, Single- and Two-Photon-Induced Amplified Spontaneous Emission.

    PubMed

    Pan, Jun; Sarmah, Smritakshi P; Murali, Banavoth; Dursun, Ibrahim; Peng, Wei; Parida, Manas R; Liu, Jiakai; Sinatra, Lutfan; Alyami, Noktan; Zhao, Chao; Alarousu, Erkki; Ng, Tien Khee; Ooi, Boon S; Bakr, Osman M; Mohammed, Omar F

    2015-12-17

    We demonstrate ultra-air- and photostable CsPbBr3 quantum dots (QDs) by using an inorganic-organic hybrid ion pair as the capping ligand. This passivation approach to perovskite QDs yields high photoluminescence quantum yield with unprecedented operational stability in ambient conditions (60 5% lab humidity) and high pump fluences, thus overcoming one of the greatest challenges impeding the development of perovskite-based applications. Due to the robustness of passivated perovskite QDs, we were able to induce ultrastable amplified spontaneous emission (ASE) in solution processed QD films not only through one photon but also through two-photon absorption processes. The latter has not been observed before in the family of perovskite materials. More importantly, passivated perovskite QD films showed remarkable photostability under continuous pulsed laser excitation in ambient conditions for at least 34 h (corresponds to 1.2 10(8) laser shots), substantially exceeding the stability of other colloidal QD systems in which ASE has been observed. PMID:26624490

  14. Spontaneous acromegaly: a retrospective case control study in German shepherd dogs.

    PubMed

    Fracassi, F; Zagnoli, L; Rosenberg, D; Furlanello, T; Caldin, M

    2014-10-01

    Acromegaly results from the overproduction of growth hormone in adulthood and is characterised by overgrowth of soft tissue and/or bone as well as insulin resistance. There are few data indicating the risk factors associated with this disease in dogs or its clinicopathological features and sequelae. The objective of this retrospective study was to catalogue and assess these aspects of the disease in German shepherd dogs (GSDs) which were found to be over-represented among acromegalic dogs attending two veterinary referral clinics over a period of 7?years. Each acromegalic dog (AD) was compared with two breed/age/sex matched controls. Clinical signs of acromegaly included panting, polyuria/polydipsia, widened interdental spaces, weakness, inspiratory stridor, macroglossia, weight gain, redundant skin folds, thick coat, exophthalmos and mammary masses. Serum alkaline phosphatase, creatine-kinase, glucose, triglyceride, phosphate ion, and 'calcium per phosphate product' concentrations were significantly higher in acromegalic animals while haemoglobin concentration, blood urea nitrogen, sodium and chloride ion concentrations, and urinary specific gravity, osmolality and fractional excretion of phosphate were significantly lower. Although, in the majority of cases clinicopathological abnormalities resolved following ovariohysterectomy, in one dog, acromegalic signs abated and insulin-like growth factor-1 concentrations normalised only following the surgical excision of mammary tumours carried out 2?months after ovariohysterectomy. The findings of this study indicate that GSDs are predisposed to the development of acromegaly with a suspected inherited susceptibility. PMID:24986315

  15. Spontaneous Gac Mutants of Pseudomonas Biological Control Strains: Cheaters or Mutualists? ?

    PubMed Central

    Driscoll, William W.; Pepper, John W.; Pierson, Leland S.; Pierson, Elizabeth A.

    2011-01-01

    Bacteria rely on a range of extracellular metabolites to suppress competitors, gain access to resources, and exploit plant or animal hosts. The GacS/GacA two-component regulatory system positively controls the expression of many of these beneficial external products in pseudomonad bacteria. Natural populations often contain variants with defective Gac systems that do not produce most external products. These mutants benefit from a decreased metabolic load but do not appear to displace the wild type in nature. How could natural selection maintain the wild type in the presence of a mutant with enhanced growth? One hypothesis is that Gac mutants are cheaters that do not contribute to the public good, favored within groups but selected against between groups, as groups containing more mutants lose access to ecologically important external products. An alternative hypothesis is that Gac mutants have a mutualistic interaction with the wild type, so that each variant benefits by the presence of the other. In the biocontrol bacterium Pseudomonas chlororaphis strain 30-84, Gac mutants do not produce phenazines, which suppress competitor growth and are critical for biofilm formation. Here, we test the predictions of these alternative hypotheses by quantifying interactions between the wild type and the phenazine- and biofilm-deficient Gac mutant within growing biofilms. We find evidence that the wild type and Gac mutants interact mutualistically in the biofilm context, whereas a phenazine-defective structural mutant does not. Our results suggest that the persistence of alternative Gac phenotypes may be due to the stabilizing role of local mutualistic interactions. PMID:21873476

  16. A feedback-controlled treadmill (treadmill-on-demand) and the spontaneous speed of walking and running in humans.

    PubMed

    Minetti, Alberto E; Boldrini, Lorenzo; Brusamolin, Laura; Zamparo, Paola; McKee, Tom

    2003-08-01

    A novel apparatus, composed by a controllable treadmill, a computer, and an ultrasonic range finder, is here proposed to help investigation of many aspects of spontaneous locomotion. The acceleration or deceleration of the subject, detected by the sensor and processed by the computer, is used to accelerate or decelerate the treadmill in real time. The system has been used to assess, in eight subjects, the self-selected speed of walking and running, the maximum "reasonable" speed of walking, and the minimum reasonable speed of running at different gradients (from level up to +25%). This evidenced the speed range at which humans neither walk nor run, from 7.2 +/- 0.6 to 8.4 +/- 1.1 km/h for level locomotion, slightly narrowing at steeper slopes. These data confirm previous results, obtained indirectly from stride frequency recordings. The self-selected speed of walking decreases with increasing gradient (from 5.0 +/- 0.8 km/h at 0% to 3.0 +/- 0.9 km/h at +25%) and seems to be approximately 30% higher than the speed that minimizes the metabolic energy cost of walking, obtained from the literature, at all the investigated gradients. The advantages, limitations, and potential applications of the newly proposed methodology in physiology, biomechanics, and pathology of locomotion are discussed in this paper. PMID:12692139

  17. VOC emissions controls for aluminum cold rolling mills

    SciTech Connect

    Genoble, A.L.; Lagoe, D.J.; Wasyluk, W.J.R.

    1997-12-31

    This paper is a case history of retrofitting VOC emissions controls to two (2) aluminum cold rolling mills at an aluminum sheet complex in central New York. The plant site was located in the northeast ozone transport region, and it was necessary to achieve compliance with VOC emissions limitations. Emissions control equipment included high efficiency filters for VOC mists and a wash oil process for scrubbing VOC vapors. All rolling oil was recovered for reuse on site. A vacuum distillation process was used to separate wash oil from rolling oil. The equipment began operating in mid-1995, and long term results have proven the validity of the recovery concept. Total project costs were $7.2 million for two (2) 60,000 ACFM systems. Project duration from the date of the initial request for equipment price quotations to the first round of stack testing was twenty (20) months. The modular construction of the vacuum distillation equipment simplified field erection and shortened the duration of field work. Stack testing indicated overall VOC collection efficiencies that exceeded regulatory requirements. Initially, problems were experienced with Method 25 stack testing methodology. Final results were confirmed by two (2) independent methods.

  18. Solid state carbon nanotube device for controllable trion electroluminescence emission.

    PubMed

    Liang, Shuang; Ma, Ze; Wei, Nan; Liu, Huaping; Wang, Sheng; Peng, Lian-Mao

    2016-03-17

    Semiconducting carbon nanotubes (CNTs) have a direct chirality-dependent bandgap and reduced dimensionality-related quantum confinement effects, which are closely related to the performance of optoelectronic devices. Here, taking advantage of the large energy separations between neutral singlet excitons and charged excitons, i.e. trions in CNTs, we have achieved for the first time all trion electroluminescence (EL) emission from chirality-sorted (8,3) and (8,4) CNT-based solid state devices. We showed that strong trion emission can be obtained as a result of localized impact excitation and electrically injected holes, with an estimated efficiency of ∼5 × 10(-4) photons per injected hole. The importance of contact-controlled carrier injection (including symmetric and asymmetric contact configurations) and EL spectral stability for gradually increasing bias were also investigated. The realization of electrically induced pure trion emission opens up a new opportunity for CNT film-based optoelectronic devices, providing a new degree of freedom in controlling the devices to extend potential applications in spin or magnetic optoelectronics fields. PMID:26953676

  19. Emission control of gas effluents from geothermal power plants.

    PubMed

    Axtmann, R C

    1975-01-01

    Geothermal steam at the world's five largest power plants contains from 0.15 to 30% noncondensable gases including CO(2), H(2)S, H(2), CH(4), N(2), H(3)BO(3), and NH(3). At four of the plants the gases are first separated from the steam and then discharged to the environment; at the fifth, the noncondensables exhaust directly to the atmosphere along with spent steam. Some CO(2) and sulfur emission rates rival those from fossil-fueled plants on a per megawatt-day basis. The ammonia and boron effluents can interfere with animal and plant life. The effects of sulfur (which emerges as H(2)S but may oxidize to SO(2)) on either ambient air quality or longterm human health are largely unknown. Most geothermal turbines are equipped with direct contact condensers which complicate emission control because they provide two or more pathways for the effluents to reach the environment. Use of direct contact condensers could permit efficient emission control if coupled to processes that produce saleable quantities of purified carbon dioxide and elemental sulfur. PMID:1132388

  20. Active Control of Combustor Instability Shown to Help Lower Emissions

    NASA Technical Reports Server (NTRS)

    DeLaat, John C.; Chang, Clarence T.

    2002-01-01

    In a quest to reduce the environmental impact of aerospace propulsion systems, extensive research is being done in the development of lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle. However, these lean-burning combustors have an increased susceptibility to thermoacoustic instabilities, or high-pressure oscillations much like sound waves, that can cause severe high-frequency vibrations in the combustor. These pressure waves can fatigue the combustor components and even the downstream turbine blades. This can significantly decrease the safe operating life of the combustor and turbine. Thus, suppression of the thermoacoustic combustor instabilities is an enabling technology for lean, low-emissions combustors. Under the Aerospace Propulsion and Power Base Research and Technology Program, the NASA Glenn Research Center, in partnership with Pratt & Whitney and United Technologies Research Center, is developing technologies for the active control of combustion instabilities. With active combustion control, the fuel is pulsed to put pressure oscillations into the system. This cancels out the pressure oscillations being produced by the instabilities. Thus, the engine can have lower pollutant emissions and long life.The use of active combustion instability control to reduce thermo-acoustic-driven combustor pressure oscillations was demonstrated on a single-nozzle combustor rig at United Technologies. This rig has many of the complexities of a real engine combustor (i.e., an actual fuel nozzle and swirler, dilution cooling, etc.). Control was demonstrated through modeling, developing, and testing a fuel-delivery system able to the 280-Hz instability frequency. The preceding figure shows the capability of this system to provide high-frequency fuel modulations. Because of the high-shear contrarotating airflow in the fuel injector, there was some concern that the fuel pulses would be attenuated to the point where they would not be effective for control. Testing in the combustor rig showed that open-loop pulsing of the fuel was, in fact, able to effectively modulate the combustor pressure. To suppress the combustor pressure oscillations due to thermoacoustic instabilities, it is desirable to time the injection of the fuel so that it interferes with the instability. A closed-loop control scheme was developed that uses combustion pressure feedback and a phase-shifting controller to time the fuel-injection pulses. Some suppression of the pressure oscillations at the 280-Hz instability frequency was demonstrated (see the next figure). However, the overall peak-to- peak pressure oscillations in the combustor were only mildly reduced. Improvements to control hardware and control methods are being continued to gain improved closed-loop reduction of the pressure oscillations.pulse the fuel at

  1. CONTROL OF AIR EMISSIONS FROM MOLYBDENUM ROASTING. VOLUME 1. EMISSIONS CHARACTERIZATION AND PARTICULATE CONTROL

    EPA Science Inventory

    The primary objective of this project was to evaluate a baghouse employing Teflon coated fabric bags for particulate recovery and control. This system was of great interest because of the corrosion resistance of Teflon coated fabric filters and this unique application in the nonf...

  2. Spontaneous Recovery

    ERIC Educational Resources Information Center

    Rescorla, Robert A.

    2004-01-01

    Spontaneous recovery from extinction is one of the most basic phenomena of Pavlovian conditioning. Although it can be studied by using a variety of designs, some procedures are better than others for identifying the involvement of underlying learning processes. A wide range of different learning mechanisms has been suggested as being engaged by

  3. DEGRADATION OF EMISSIONS CONTROL PERFORMANCE OF WOODSTOVES IN CRESTED BUTTE, CO

    EPA Science Inventory

    The report discusses the degradation of emissions control performance of woodstoves in Crested Butte, Colorado. Four seasons of field monitoring of EPA-certified woodstoves in and around Crested Butte has demonstrated some significant failures in emissions control performance. In...

  4. COMBUSTION CONTROL OF PCDD/PCDF EMISSIONS FROM MUNICIPAL WASTE INCINERATORS IN NORTH AMERICA

    EPA Science Inventory

    The paper discusses combustion control of emissions of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) from municipal waste incinerators in North America. New regulations to control air pollution emissions from municipal waste incineration have b...

  5. Effects of a T-type calcium channel blocker, ABT-639, on spontaneous activity in C-nociceptors in patients with painful diabetic neuropathy: a randomized controlled trial.

    PubMed

    Serra, Jordi; Duan, W Rachel; Locke, Charles; Sol, Rom; Liu, Wei; Nothaft, Wolfram

    2015-11-01

    T-type calcium channels are a potential novel target for treatment of neuropathic pain such as painful diabetic neuropathy. ABT-639 is a peripherally acting highly selective T-type Ca(v)3.2 calcium channel blocker that has demonstrated analgesic efficacy in preclinical models and may have the potential to reduce spontaneous fiber activity. Microneurography is a unique technique that directly assesses the function of peripheral sensory afferents and measures abnormal spontaneous activity in single peripheral nociceptive C fibers. Abnormal spontaneous activity in C-nociceptors functions as a marker for spontaneous pain, as reduction of this activity could indicate analgesic efficacy. This randomized, double-blind controlled study evaluated the effects of a single 100-mg oral dose of ABT-639, compared with placebo, on abnormal spontaneous activity in peripheral C-nociceptors, measured for the first time by microneurography in adult patients with painful diabetic neuropathy. Lidocaine was included in this study and compared with placebo. Pharmacokinetics and safety of ABT-639 were evaluated. Thirty-nine patients were randomized, and a total of 56 analyzable C-nociceptors with spontaneous activity were identified in 34 patients. There were no significant differences in C-nociceptor activities after ABT-639 treatment vs placebo. Similar findings were observed for lidocaine vs placebo. There were no clinically significant findings in the safety of ABT-639. Further research of T-type Ca(v)3.2 calcium channels as potential treatment targets for painful diabetic neuropathy is warranted. The utilization of microneurography as a means to measure abnormal activity in C-nociceptors in human clinical studies opens new possibilities for future studies of compounds targeting peripheral nerve hyperexcitability. ClinicalTrials.gov identifier: NCT01589432. PMID:26035253

  6. Coal cleaning as an SO sub 2 emissions control option

    SciTech Connect

    Leadenham, D.J.

    1988-01-01

    Continuing analysis of EPRI Coal Combustion Systems R D programs led to an investigation of coal cleaning as an SO{sub 2} air emissions control. Pending acid rain legislation requiring significant statewide SO{sub 2} reductions suggested coal cleaning as an adjunct air pollution control similar to switching fuels to low sulfur coals. This book discusses current publications on modeling cost and quality of cleaned coals which permitted an objective study using a computer program. Data on coals suitable for a cleaning analysis exist and more ambitious coal databases are in development and planning. The study suggests that the market for coal cleaning is not strongly affected by technologies used to achieve SO{sub 2} control and is only midly sensitive to the price of compliance coal.

  7. 40 CFR 63.325 - Determination of equivalent emission control technology.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... control technology. 63.325 Section 63.325 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Determination of equivalent emission control technology. (a) Any person requesting that the use of certain... equivalent emission reductions: (1) Diagrams, as appropriate, illustrating the emission control...

  8. 40 CFR 75.34 - Units with add-on emission controls.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 17 2014-07-01 2014-07-01 false Units with add-on emission controls... add-on emission controls. (a) The owner or operator of an affected unit equipped with add-on SO2 and... which the add-on emission controls are documented to be operating properly, as described in the...

  9. 40 CFR 75.34 - Units with add-on emission controls.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Units with add-on emission controls... add-on emission controls. (a) The owner or operator of an affected unit equipped with add-on SO2 and... which the add-on emission controls are documented to be operating properly, as described in the...

  10. 40 CFR 75.34 - Units with add-on emission controls.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 17 2013-07-01 2013-07-01 false Units with add-on emission controls... add-on emission controls. (a) The owner or operator of an affected unit equipped with add-on SO2 and... which the add-on emission controls are documented to be operating properly, as described in the...

  11. 40 CFR 75.34 - Units with add-on emission controls.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 16 2011-07-01 2011-07-01 false Units with add-on emission controls... add-on emission controls. (a) The owner or operator of an affected unit equipped with add-on SO2 and... which the add-on emission controls are documented to be operating properly, as described in the...

  12. 40 CFR 75.34 - Units with add-on emission controls.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 17 2012-07-01 2012-07-01 false Units with add-on emission controls... add-on emission controls. (a) The owner or operator of an affected unit equipped with add-on SO2 and... which the add-on emission controls are documented to be operating properly, as described in the...

  13. Mine planning and emission control strategies using geostatistics

    SciTech Connect

    Martino, F.; Kim, Y.C.

    1983-03-01

    This paper reviews the past four years' research efforts performed jointly by the University of Arizona and the Homer City Owners in which geostatistics were applied to solve various problems associated with coal characterization, mine planning, and development of emission control strategies. Because geostatistics is the only technique which can quantify the degree of confidence associated with a given estimate (or prediction), it played an important role throughout the research efforts. Through geostatistics, it was learned that there is an urgent need for closely spaced sample information, if short-term coal quality predictions are to be made for mine planning purposes.

  14. Molecular host-guest energy-transfer system with an ultralow amplified spontaneous emission threshold employing an ambipolar semiconducting host matrix.

    PubMed

    Toffanin, Stefano; Capelli, Raffaella; Hwu, Tsyr-Yuan; Wong, Ken-Tsung; Pltzing, Tobias; Frst, Michael; Muccini, Michele

    2010-01-14

    We report on the characteristics of a host-guest lasing system obtained by coevaporation of an oligo(9,9-diarylfluorene) derivative named T3 with the red-emitter 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran dye (DCM). We demonstrate that the ambipolar semiconductor T3 can be implemented as an active matrix in the realization of a host-guest system in which an efficient energy transfer takes place from the T3 matrix to the lasing DCM molecules. We performed a detailed spectroscopic study on the system by systematically varying the DCM concentration in the T3 matrix. Measurements of steady-state photoluminescence (PL), PL quantum yield (PLQY), time-resolved picosecond PL, and amplified spontaneous emission (ASE) threshold are used to optimize the acceptor concentration at which the ASE from DCM molecules takes place with the lowest threshold. The sample with a DCM relative deposition ratio of 2% shows an ASE threshold as low as 0.6 kW/cm(2) and a net optical gain measured by femtosecond time-resolved pump-and-probe spectroscopy as high as 77 cm(-1). The reference model system Alq(3):DCM sample measured in exactly the same experimental conditions presents an one-order-of-magnitude higher ASE threshold. The ASE threshold of T3:DCM is the lowest reported to date for a molecular host-guest energy-transfer system, which makes the investigated blend an appealing system for use as an active layer in lasing devices. In particular, the ambipolar charge transport properties of the T3 matrix and its field-effect characteristics make the host-guest system presented here an ideal candidate for the realization of electrically pumped organic lasers. PMID:19961197

  15. Nonlinear theory of a two-photon correlated-spontaneous-emission laser: A coherently pumped two-level--two-photon laser

    SciTech Connect

    Lu, N.; Zhao, F.; Bergou, J.

    1989-05-15

    We develop a nonlinear theory of a two-photon correlated-spontaneous-emission laser (CEL) by using an effective interaction Hamiltonian for a two-level system coupled by a two-photon transition. Assuming that the active atoms are prepared initially in a coherent superposition of two atomic levels involved in the two-photon transition, we derive a master equation for the field-density operator by using our quantum theory for coherently pumped lasers. The steady-state properties of the two-photon CEL are studied by converting the field master equation into a Fokker-Planck equation for the antinormal-ordering Q representation of the field-density operator. Because of the injected atomic coherence, the drift and diffusion coefficients become phase sensitive. This leads to laser phase locking and an extra two-photon CEL gain. The laser field can build up from a vacuum in the no-population-inversion region, in contrast to an ordinary two-photon laser for which triggering is needed. We find an approximate steady-state solution of the Q representation for the laser field, which consists of two identical peaks of elliptical type. We calculate the phase variance and, for any given mean photon number, obtain the minimum variance in the phase quadrature as a function of the initial atomic variables. Squeezing of the quantum noise in the phase quadrature is found and it exhibits the following features: (1) it is possible only when the laser intensity is smaller than a certain value; (2) it becomes most significant for small mean photon number, which is achievable in the no-population-inversion region; and (3) a maximum of 50% squeezing can be asymptotically approached in the small laser intensity limit.

  16. Role of hindbrain melanocortin-4 receptor activity in controlling cardiovascular and metabolic functions in spontaneously hypertensive rats

    PubMed Central

    do Carmo, Jussara M.; da Silva, Alexandre A.; Hall, John E.

    2016-01-01

    Background Although we previously demonstrated that activation of central nervous system (CNS) melanocortin3/4 receptors (MC3/4R) play a key role in blood pressure (BP) regulation, especially in spontaneously hypertensive rats (SHRs), the importance of hindbrain MC4R is still unclear. Method In the present study, we examined the cardiovascular and metabolic effects of chronic inhibition of MC3/4R in the hindbrain of SHRs and normotensive WistarKyoto (WKY) rats. Male WKY rats (n = 6) and SHRs (n = 7) were implanted with telemetry probes to measure BP and heart rate (HR) 24 h/day, and an intracerebroventricular cannula was placed into the fourth ventricle. After 10 days of recovery and 5 days of control measurements, the MC3/4R antagonist (SHU-9119) was infused into the fourth ventricle (1 nmol/h) to antagonize hindbrain MC4R for 10 days, followed by a 5-day recovery period. Results Chronic hindbrain MC3/4R antagonism significantly increased food intake and body weight in WKY rats (17 1 to 35 2 g/day and 280 8 to 353 8 g) and SHRs (19 2 to 35 2 g/day and 323 7 to 371 11 g), and markedly increased fasting insulin and leptin levels while causing no changes in blood glucose levels (99 4 to 87 4 and 89 5 to 89 4 mg/dl, respectively, for WKY rats and SHRs). Chronic SHU-9119 infusion reduced mean arterial pressure and HR similarly in WKY rats (?8 1 mmHg and ?47 3 b.p.m.) and SHRs (?11 3 mmHg and ?44 3 b.p.m.). Conclusion These results suggest that although hindbrain MC4R activity contributes to appetite and HR regulation, it does not play a major role in mediating the elevated BP in SHRs. PMID:25668357

  17. Survey of Emissions Associated with Enclosed Combustor Emission Control Devices in the Denver-Julesburg Basin

    NASA Astrophysics Data System (ADS)

    Knighton, W. B.; Floerchinger, C. R.; Wormhoult, J.; Massoli, P.; Fortner, E.; Brooks, B.; Roscioli, J. R.; Bon, D.; Herndon, S. C.

    2014-12-01

    Volatile organic compounds (VOCs) play an important role in local and regional air quality. A large source of VOCs comes from the oil and gas industry and the Denver-Julesburg Basin (D-J Basin) has seen a sharp increase in production in recent years primarily due to advances in horizontal drilling techniques. To help curb emissions with extraction and production of natural gas and its associated oil, emission control devices are required for facilities emitting over 6 tons of hydrocarbons per year. Within the ozone non-attainment area, which encompasses Denver and much of the front range, enclosed combustion devices (enclosed flares) are required to reduce hydrocarbon emissions by at least 95%. While certification tests indicate that these enclosed combustor devices provide high destruction removal efficiencies, there is considerable interest in knowing how well they perform in the field. As part of Front Range Air Pollution and Photochemistry Experiment (FRAPPE) project conducted during the Summer of 2014, the Aerodyne Mobile Laboratory (AML) surveyed oil and gas operations within the Wattenberg gas field and the surrounding D-J Basin. The AML deployed a full suite of gas and particle phase instrumentation providing a comprehensive set of on-line, real-time measurements for the major natural gas components (methane and ethane) and their combustion products (CO2, CO, NOx) using a variety of spectroscopic techniques. Additional gas phase organic gas emissions were made using a proton transfer reaction mass spectrometer (PTR-MS). Particle number and composition were determined using a condensation particle counter and an Aerodyne Aerosol Mass Spectrometer (AMS). A summary of the number of enclosed combustor devices measured and their observed combustion efficiencies will be presented.

  18. Control of acid mist emissions from FGD systems

    SciTech Connect

    Dahlin, R S; Brown, T D

    1991-01-01

    Improved control of acid mist emissions can be achieved by replacing or augmenting the conventional mist eliminators with a wet electrostatic precipitator (WESP). This paper describes a two-phased study performed to determine the degree of control that can be achieved with this approach. Phase I was a study of the electrical operation of a lab-scale WESP collecting an acid mist from a coal combustion pilot plant equipped with a spray chamber. The results of this study were used to develop and validate a computer model of the WESP. In Phase II, measurements were made at two utility scrubber installations to determine the loadings of acid mist, fly ash, and scrubber carryover. These measurements were used as input to the model to project the performance of a retrofitted WESP.

  19. Work with existing hardware to maximize emissions control

    SciTech Connect

    Makansi, J.

    1995-03-01

    Regulatory uncertainty cripples capital investment, but has also helped unleash a surprising level of ingenuity to lower the costs of compliance. Techniques described here could become popular as CAA Phase 2 unfolds. Regulated rate-of-return structures are eroding as competitive forces erupt, permanently changing the business landscape. Meanwhile, complying with Title IV of the Clean Air Act Amendments of 1990 (CAA), a relative certainty, is clouded by a host of other potential environmental compliance issues -- air-toxics regulations, solid-waste restrictions, global warming and CO{sub 2} discharges, water management, and differing state, regional, and local regulations. As a result, utilities are reacting by spending as little as possible, especially in terms of compliance with CAA Phase 2. But by doing so, they are applying and/or demonstrating a variety of low-cost techniques that achieve significant emissions reductions. In some cases, these techniques may simply involve a trade off of capital investment for higher operating costs. But in a significant number of other cases, the techniques could emerge as key design improvements for the new generation of powerplants. To these techniques must be added the buying of SO{sub 2} allowances as a replacement for, or enhancement of, SO{sub 2}removal strategies. What many of these techniques have in common are (1) maximum use of existing hardware and (2) integration of emissions control into standard powerplant components. Broadly surveying the industry reveals the following general areas that are explored here: fuel changes, reducing NO{sub x} emissions through better control over the combustion process, employing low-cost catalyst and/or selective non-catalytic reduction (SNCR), getting more out of existing flue-gas desulfurization (FGD) processes, and improving existing particulate collection devices.

  20. "APEC Blue": Secondary Aerosol Reductions from Emission Controls in Beijing.

    PubMed

    Sun, Yele; Wang, Zifa; Wild, Oliver; Xu, Weiqi; Chen, Chen; Fu, Pingqing; Du, Wei; Zhou, Libo; Zhang, Qi; Han, Tingting; Wang, Qingqing; Pan, Xiaole; Zheng, Haitao; Li, Jie; Guo, Xiaofeng; Liu, Jianguo; Worsnop, Douglas R

    2016-01-01

    China implemented strict emission control measures in Beijing and surrounding regions to ensure good air quality during the 2014 Asia-Pacific Economic Cooperation (APEC) summit. We conducted synchronous aerosol particle measurements with two aerosol mass spectrometers at different heights on a meteorological tower in urban Beijing to investigate the variations in particulate composition, sources and size distributions in response to emission controls. Our results show consistently large reductions in secondary inorganic aerosol (SIA) of 61-67% and 51-57%, and in secondary organic aerosol (SOA) of 55% and 37%, at 260 m and ground level, respectively, during the APEC summit. These changes were mainly caused by large reductions in accumulation mode particles and by suppression of the growth of SIA and SOA by a factor of 2-3, which led to blue sky days during APEC commonly referred to as "APEC Blue". We propose a conceptual framework for the evolution of primary and secondary species and highlight the importance of regional atmospheric transport in the formation of severe pollution episodes in Beijing. Our results indicate that reducing the precursors of secondary aerosol over regional scales is crucial and effective in suppressing the formation of secondary particulates and mitigating PM pollution. PMID:26891104

  1. Controlling mercury emissions from coal-fired power plants

    SciTech Connect

    Chang, R.

    2009-07-15

    Increasingly stringent US federal and state limits on mercury emissions form coal-fired power plants demand optimal mercury control technologies. This article summarises the successful removal of mercury emissions achieved with activated carbon injection and boiler bromide addition, technologies nearing commercial readiness, as well as several novel control concepts currently under development. It also discusses some of the issues standing in the way of confident performance and cost predictions. In testing conducted on western coal-fired units with fabric filters or TOXECON to date, ACI has generally achieved mercury removal rates > 90%. At units with ESPs, similar performance requires brominated ACI. Alternatively, units firing western coals can use boiler bromide addition to increase flue gas mercury oxidation and downstream capture in a wet scrubber, or to enhance mercury removal by ACI. At eastern bituminous fired units with ESPs, ACI is not as effective, largely due to SO{sub 3} resulting from the high sulfur content of the coal or the use of SO{sub 3} flue gas conditioning to improve ESP performance. 7 refs., 3 figs.

  2. Controlling GT arc length from arc light emissions

    SciTech Connect

    Richardson, R.W.; Edwards, F.S.

    1996-12-31

    Conventional systems for mechanized Gas Tungsten Arc (GTA) welding control arc length by utilizing its well known relationship with arc voltage. Such systems maintain a constant arc voltage by movement of the torch relative to the work surface. This has proven to be practicable over the years where the welding machine operator can make frequent visual observations of arc length, and then adjust the arc voltage set point in order to compensate for subtle changes in the arc length/arc voltage relationship. Fully automated robotic type welding systems do not present this luxury since weld cycles are required to proceed over long periods without manual intervention. The key fundamental difficulty is that the arc voltage is dominated by large voltage drops near the electrode surfaces which are independent of arc length. This paper presents a review of past and related work in the area, followed by results of a new study of arc light sensitivity and its application to arc length control. For this work, a standard automatic voltage controller was used which was modified to receive either arc voltage or a suitably scaled voltage signal derived from an arc light emission sensor. This allowed a direct comparison of conventional and arc light based control approaches. It was found that arc light control behaved more robustly when encountering disturbances which are known to seriously trouble a voltage based control. A prime example is welding from one base material onto another which was found to produce only a minor effect on a light based control, but unacceptable behavior of a voltage control. Details of experiments and results are presented.

  3. CO₂ laser emission modes to control enamel erosion.

    PubMed

    Scatolin, Renata Siqueira; Alonso-Filho, Fernando Luiz; Galo, Rodrigo; Rios, Daniela; Borsatto, Maria Cristina; Corona, Silmara Aparecida Milori

    2015-08-01

    Considering the importance and prevalence of dental erosion, the aim of this in vitro study was to evaluate the influence of different modes of pulse emission of CO2 laser associated or not to acidulated phosphate fluoride (APF) 1.23% gel, in controlling enamel erosion by profilometry. Ninety-six fragments of bovine enamel were flattened and polished, and the specimens were subjected to initial erosive challenge with hydrochloric acid (pH = 2). Specimens were randomly assigned according to surface treatment: APF 1.23% gel and gel without fluoride (control), and subdivided according to the modes of pulse CO2 laser irradiation: no irradiation (control), continuous, ultrapulse, and repeated pulse (n = 12). After surface treatment, further erosive challenges were performed for 5 days, 4 × 2 min/day. Enamel structure loss was quantitatively determined by a profilometer, after surface treatment and after 5 days of erosive challenges. Two-away ANOVA revealed a significant difference between the pulse emission mode of the CO2 laser and the presence of fluoride (P ≤ 0.05). The Duncan's test showed that CO2 laser irradiation in continuous mode and the specimens only received fluoride, promoted lower enamel loss than that other treatments. A lower dissolution of the enamel prisms was observed when it was irradiated with CO2 laser in continuous mode compared other groups. It can be concluded that CO2 laser irradiation in continuous mode was the most effective to control the enamel structure loss submitted to erosive challenges with hydrochloric acid. PMID:25988247

  4. Automated Boiler Combustion Controls for Emission Reduction and Efficiency Improvement

    SciTech Connect

    1998-12-02

    In the late 1980s, then President Bush visited Krakow, Poland. The terrible air quality theremotivated him to initiate a USAID-funded program, managed by DOE, entitled �Krakow Clean Fossil Fuels and Energy Efficiency Program.� The primary objective of this program was to encourage the formation of commercial ventures between U.S. and Polish firms to provide equipment and/or services to reduce pollution from low-emission sources in Krakow, Poland. This program led to the award of a number of cooperative agreements, including one to Control Techtronics International. The technical objective of CTI�s cooperative agreement is to apply combustion controls to existing boiler plants in Krakow and transfer knowledge and technology through a joint U.S. and Polish commercial venture. CTI installed automatic combustion controls on five coal boilers for the district heating system in Krakow. Three of these were for domestic hot-water boilers, and two were for steam for industrial boilers. The following results have occurred due to the addition of CTI�s combustion controls on these five existing boilers: ! 25% energy savings ! 85% reduction in particulate emissions The joint venture company CTI-Polska was then established. Eleven additional technical and costing proposals were initiated to upgrade other coal boilers in Krakow. To date, no co-financing has been made available on the Polish side. CTI-Polska continues in operation, serving customers in Russia and Ukraine. Should the market in Poland materialize, the joint venture company is established there to provide equipment and service.

  5. LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL

    SciTech Connect

    Don Augenstein; Ramin Yazdani; Rick Moore; Michelle Byars; Jeff Kieffer; Professor Morton Barlaz; Rinav Mehta

    2000-02-26

    Controlled landfilling is an approach to manage solid waste landfills, so as to rapidly complete methane generation, while maximizing gas capture and minimizing the usual emissions of methane to the atmosphere. With controlled landfilling, methane generation is accelerated to more rapid and earlier completion to full potential by improving conditions (principally moisture, but also temperature) to optimize biological processes occurring within the landfill. Gas is contained through use of surface membrane cover. Gas is captured via porous layers, under the cover, operated at slight vacuum. A field demonstration project has been ongoing under NETL sponsorship for the past several years near Davis, CA. Results have been extremely encouraging. Two major benefits of the technology are reduction of landfill methane emissions to minuscule levels, and the recovery of greater amounts of landfill methane energy in much shorter times, more predictably, than with conventional landfill practice. With the large amount of US landfill methane generated, and greenhouse potency of methane, better landfill methane control can play a substantial role both in reduction of US greenhouse gas emissions and in US renewable energy. The work described in this report, to demonstrate and advance this technology, has used two demonstration-scale cells of size (8000 metric tons [tonnes]), sufficient to replicate many heat and compaction characteristics of larger ''full-scale'' landfills. An enhanced demonstration cell has received moisture supplementation to field capacity. This is the maximum moisture waste can hold while still limiting liquid drainage rate to minimal and safely manageable levels. The enhanced landfill module was compared to a parallel control landfill module receiving no moisture additions. Gas recovery has continued for a period of over 4 years. It is quite encouraging that the enhanced cell methane recovery has been close to 10-fold that experienced with conventional landfills. This is the highest methane recovery rate per unit waste, and thus progress toward stabilization, documented anywhere for such a large waste mass. This high recovery rate is attributed to moisture, and elevated temperature attained inexpensively during startup. Economic analyses performed under Phase I of this NETL contract indicate ''greenhouse cost effectiveness'' to be excellent. Other benefits include substantial waste volume loss (over 30%) which translates to extended landfill life. Other environmental benefits include rapidly improved quality and stabilization (lowered pollutant levels) in liquid leachate which drains from the waste.

  6. Implementing Strategies for Drying and Pressing Wood Without Emissions Controls

    SciTech Connect

    Sujit Banerjee; Terrance Conners

    2007-09-07

    Drying and pressing wood for the manufacture of lumber, particleboard, oriented strand board (OSB), veneer and medium density fiberboard (MDF) release volatile organic compounds (VOCs) into the atmosphere. These emissions require control equipment that are capital-intensive and consume significant quantities of natural gas and electricity. The objective of our work was to understand the mechanisms through which volatile organic compounds are generated and released and to develop simple control strategies. Of the several strategies developed, two have been implemented for OSB manufacture over the course of this study. First, it was found that increasing final wood moisture by about 2-4 percentage points reduced the dryer emissions of hazardous air pollutants by over 70%. As wood dries, the escaping water evaporatively cools the wood. This cooling tapers off wood when the wood is nearly dry and the wood temperature rises. Thermal breakdown of the wood tissue occurs and VOCs are released. Raising the final wood moisture by only a few percentage points minimizes the temperature rise and reduces emissions. Evaporative cooling also impacts has implications for VOC release from wood fines. Flaking wood for OSB manufacture inevitable generates fines. Fines dry out rapidly because of their high surface area and evaporative cooling is lost more rapidly than for flakes. As a result, fines emit a disproportionate quantity of VOCs. Fines can be reduced in two ways: through screening of the green furnish and through reducing their generation during flaking. The second approach is preferable because it also increased wood yield. A procedure to do this by matching the sharpness angle of the flaker knife to the ambient temperature was also developed. Other findings of practical interests are as follows: Dielectric heating of wood under low-headspace conditions removes terpenes and other extractives from softwood; The monoterpene content in trees depend upon temperature and seasonal effects; Method 25A emissions from lumber drying can be modeled from a knowledge of the airflow through the kiln; A heat transfer model shows that VOCs released during hot-pressing mainly originate from the surface of the board; and Boiler ash can be used to adsorb formaldehyde from air streams.

  7. N2O and NO2 Emissions from Heavy-Duty Diesel Trucks with Advanced Emission Controls

    NASA Astrophysics Data System (ADS)

    Preble, C.; Harley, R.; Kirchstetter, T.

    2014-12-01

    Diesel engines are the largest source of nitrogen oxides (NOx) emissions nationally, and also a major contributor to the black carbon (BC) fraction of fine particulate matter (PM). Recently, diesel particle filter (DPF) and selective catalytic reduction (SCR) emission control systems that target exhaust PM and NOx have become standard equipment on new heavy-duty diesel trucks. However, the deliberate catalytic oxidation of engine-out nitric oxide (NO) to nitrogen dioxide (NO2) in continuously regenerating DPFs leads to increased tailpipe emission of NO2. This is of potential concern due to the toxicity of NO2 and the resulting increases in atmospheric formation of other air pollutants such as ozone, nitric acid, and fine PM. While use of SCR reduces emissions of both NO and NO2, it may lead to increased emissions of nitrous oxide (N2O), a potent greenhouse gas. Here we report results from on-road measurements of heavy-duty diesel truck emissions conducted at the Port of Oakland and the Caldecott Tunnel in the San Francisco Bay Area. Emission factors (g pollutant per kg of diesel) were linked via recorded license plates to individual truck attributes, including engine model year and installed emission control equipment. Between 2009 and 2013, the fraction of DPF-equipped trucks at the Port of Oakland increased from 2 to 99%, and median engine age decreased from 11 to 6 years. Over the same period, fleet-average emission factors for black carbon and NOx decreased by 76 ± 22% and 53 ± 8%, respectively. However, direct emissions of NO2 increased, and consequently the NO2/NOx emission ratio increased from 0.03 ± 0.02 to 0.18 ± 0.03. Older trucks retrofitted with DPFs emitted approximately 3.5 times more NO2 than newer trucks equipped with both DPF and SCR. Preliminary data from summer 2014 measurements at the Caldecott Tunnel suggest that some older trucks have negative emission factors for N2O, and that for newer trucks, N2O emission factors have changed sign and are significantly increased. More comprehensive analysis of the effects of SCR on diesel NOx and N2O emissions will be reported in the presentation. These on-road emission studies indicate that advanced emission control systems such as DPF and SCR dramatically reduce PM and NOx emissions, but can cause undesirable side effects like increased NO2 and N2O emissions.

  8. A bi-hemispheric neuronal network model of the cerebellum with spontaneous climbing fiber firing produces asymmetrical motor learning during robot control

    PubMed Central

    Pinzon-Morales, Ruben-Dario; Hirata, Yutaka

    2014-01-01

    To acquire and maintain precise movement controls over a lifespan, changes in the physical and physiological characteristics of muscles must be compensated for adaptively. The cerebellum plays a crucial role in such adaptation. Changes in muscle characteristics are not always symmetrical. For example, it is unlikely that muscles that bend and straighten a joint will change to the same degree. Thus, different (i.e., asymmetrical) adaptation is required for bending and straightening motions. To date, little is known about the role of the cerebellum in asymmetrical adaptation. Here, we investigate the cerebellar mechanisms required for asymmetrical adaptation using a bi-hemispheric cerebellar neuronal network model (biCNN). The bi-hemispheric structure is inspired by the observation that lesioning one hemisphere reduces motor performance asymmetrically. The biCNN model was constructed to run in real-time and used to control an unstable two-wheeled balancing robot. The load of the robot and its environment were modified to create asymmetrical perturbations. Plasticity at parallel fiber-Purkinje cell synapses in the biCNN model was driven by error signal in the climbing fiber (cf) input. This cf input was configured to increase and decrease its firing rate from its spontaneous firing rate (approximately 1 Hz) with sensory errors in the preferred and non-preferred direction of each hemisphere, as demonstrated in the monkey cerebellum. Our results showed that asymmetrical conditions were successfully handled by the biCNN model, in contrast to a single hemisphere model or a classical non-adaptive proportional and derivative controller. Further, the spontaneous activity of the cf, while relatively small, was critical for balancing the contribution of each cerebellar hemisphere to the overall motor command sent to the robot. Eliminating the spontaneous activity compromised the asymmetrical learning capabilities of the biCNN model. Thus, we conclude that a bi-hemispheric structure and adequate spontaneous activity of cf inputs are critical for cerebellar asymmetrical motor learning. PMID:25414644

  9. Particulate-phase and gaseous elemental mercury emissions during biomass combustion: controlling factors and correlation with particulate matter emissions.

    PubMed

    Obrist, Daniel; Moosmller, Hans; Schrmann, Roger; Chen, L W Antony; Kreidenweis, Sonia M

    2008-02-01

    Mercury emissions from wildfires are significant natural sources of atmospheric mercury, but little is known about what controls speciation of emissions important to mercury deposition processes. The goal of this study was to quantify gaseous elemental mercury (GEM) and particulate-phase mercury (PHg) emissions from biomass combustion to identify key factors controlling the speciation. Emissions were characterized in an exhaust stack 17 m above fires using a gaseous mercury analyzer and quartz-fiber filters. Fuels included fresh and air-dried leaves, needles, and branches with different fuel moistures (9-95% of dry weight) and combustion properties (e.g., from < 10 to 90% of fire durations characterized by flaming phases). Fuel moisture was the overall driving factor defining emissions, with GEM being the dominant fraction (> or = 95%) in low moisture fuels and substantial PHg contributions--up to 50% of total mercury emissions--in fresh fuels. High PHg emissions were observed during smoldering combustion whereas flaming-dominated fires showed insignificant PHg emissions. PHg mass emissions were correlated with particulate matter (PM; r2 = 0.67), organic carbon (OC; r2 = 0.63) and sulfur (S; r2 = 0.46) mass emissions, but not with elemental carbon (EC) nor with the total mercury emissions. These data suggest that the formation of PHg involves similar processes as the formation of particulate OC, for example condensation of volatile species onto preexisting smoke particles during cooling and dilution. Based on the observed relationship between PM and OC mass concentrations and published emission inventories, we estimate global PHg emissions by wildfires of 4-5 Mg yr(-1). PMID:18323093

  10. Three years operation demonstrates exhaust emission control system

    SciTech Connect

    1995-10-01

    The first field installation of a patented NO{sub x} emissions system completed its third year of operation as a demonstration site last August. The cogeneration site is powered by three Caterpillar 350 kW G398 natural gas-fueled engines. The Hybrid Low NO{sub x} system has achieved NO{sub x} and CO levels below 10 ppm consistently. Although this system initially appears complicated and somewhat sophisticated, it has been relatively maintenance free and easy to operate, according to university officials. Petrocon Technologies, of Beaumont, Texas, acquired the license to use the technology in 1994. The first step in the Hybrid Low NO{sub x} system`s process is an afterburner fired at substoichiometric conditions to increase the temperature while also increasing the CO content of the engine exhaust. The added fuel consumption of the burner limits the economy of the system to sites that have use for the additional thermal energy. Cogeneration plants are good candidates. Downstream from the burner, the high-temperature, CO-enriched exhaust passes through a heat recovery steam generator where the gas temperature is reduced to about 538{degree}C. Exhaust then passes over an Allied Signal-supplied reduction catalyst, where NO{sub x} is reduced to below 10 ppm. Controlled levels of CO in contact with the proprietary catalyst is the primary factor in achieving such extraordinarily low NO{sub x} emission levels.

  11. Solar control of the earth's emission of energetic O(+)

    NASA Technical Reports Server (NTRS)

    Lennartsson, W.

    1991-01-01

    Energetic (0.1-16 keV/e) O(+) data obtained in the earth's plasma sheet (between 10 and 23 RE) by an ion mass spectrometer on the ISEE-1 spacecraft are compared statistically with published data on the concurrent solar wind and IMF. The most strongly variable parameter of the plasma sheet O(+) is its density, which is found to be well correlated with certain solar wind parameters, especially with the solar wind flow speed and the IMF component perpendicular to the flow vector. When those two solar wind parameters are combined to form an electric field (-v x B), both the number density and the energy density of the O(+) are found to vary in proportion to the square of that electric field, on average, suggesting that the emission of energetic O(+) ions from the earth may be powered by that same field. Based on this and on the previously published correlation with solar activity, it is argued that the emission of O(+) is controlled by a combination of HF (ionizing) and quasi-static (accelerating) solar electromagnetic fields.

  12. Control of the emissions of transportation and stationary diesel engines

    SciTech Connect

    Levendis, Y.A.

    1996-12-31

    This manuscript describes a novel exhaust aftertreatment system for effective reduction of all diesel engine emissions. This system employs high-efficiency ceramic filter elements and filtered exhaust gas recirculation (EGR) to control particulate and NO{sub x} emissions. The filters are periodically regenerated aerodynamically, that is, by pulses of compressed air flowing in the opposite to the exhaust direction. The fact that the filtration system is kept at moderate temperatures, at all times, promotes the condensation of volatile hydrocarbons on the soot. Results obtained from extensive road-testing of various configurations of such systems show that (a) soot filtration efficiencies of over 99% can be achieved, (b) volatile hydrocarbon reductions of over 50% are feasible by condensation and (c) 50% reduction of NO{sub x} can be obtained with 20% EGR. Additional benefits include capture of ash and sulfates. To accommodate engines of different sizes a multi-module system is proposed. The optimum number of filters and the frequency of regeneration varies according to the size of the engine. Upon regeneration, soot is collected in a separate chamber where it is incinerated or it is periodically removed by a vacuum system.

  13. Catalytic destruction vs. adsorption in controlling dioxin emission.

    PubMed

    Hsu, Wei Ting; Hung, Pao Chen; Chang, Moo Been

    2015-12-01

    This study investigates the removal efficiencies of PCDD/Fs achieved with a catalytic filter (CF) and with activated carbon injection followed by bag filter (ACI+BF) as applied in an industrial waste incinerator (IWI) and a hazardous waste incinerator (HWI), respectively. Catalytic filtration has been successfully applied to remove PCDD/Fs from gas streams. Comparing the CF to the ACI+BF system, it appears that the PCDD/F removal efficiency achieved with a CF is higher than that of an ACI+BF system. The PCDD/F emissions from both incinerators are well controlled to meet the regulatory limit of 0.1 ng I-TEQ/Nm(3). Additionally, the PCDD/F concentration in BF ash is higher than the regulation limit of Taiwan (1.0 ng I-TEQ/g). In contrast, the PCDD/F concentration in CF ash is only 0.274 ng I-TEQ/g. The difference is attributed to the fact that the ACI+BF system just transfers PCDD/Fs from gas phase to solid phase and further increases the PCDD/F concentration in fly ash, while CF technology effectively destroys the gas-phase PCDD/Fs. Therefore, the disposal of the fly ash discharged from CF would be less expensive compared with the fly ash discharged from the ACI+BF system. In this study, the PCDD/F emission factors of both incinerators are also established. PMID:26350401

  14. Methane emissions from process equipment at natural gas production sites in the United States: pneumatic controllers.

    PubMed

    Allen, David T; Pacsi, Adam P; Sullivan, David W; Zavala-Araiza, Daniel; Harrison, Matthew; Keen, Kindal; Fraser, Matthew P; Daniel Hill, A; Sawyer, Robert F; Seinfeld, John H

    2015-01-01

    Emissions from 377 gas actuated (pneumatic) controllers were measured at natural gas production sites and a small number of oil production sites, throughout the United States. A small subset of the devices (19%), with whole gas emission rates in excess of 6 standard cubic feet per hour (scf/h), accounted for 95% of emissions. More than half of the controllers recorded emissions of 0.001 scf/h or less during 15 min of measurement. Pneumatic controllers in level control applications on separators and in compressor applications had higher emission rates than controllers in other types of applications. Regional differences in emissions were observed, with the lowest emissions measured in the Rocky Mountains and the highest emissions in the Gulf Coast. Average methane emissions per controller reported in this work are 17% higher than the average emissions per controller in the 2012 EPA greenhouse gas national emission inventory (2012 GHG NEI, released in 2014); the average of 2.7 controllers per well observed in this work is higher than the 1.0 controllers per well reported in the 2012 GHG NEI. PMID:25488196

  15. Application of microturbines to control emissions from associated gas

    SciTech Connect

    Schmidt, Darren D.

    2013-04-16

    A system for controlling the emission of associated gas produced from a reservoir. In an embodiment, the system comprises a gas compressor including a gas inlet in fluid communication with an associated gas source and a gas outlet. The gas compressor adjusts the pressure of the associated gas to produce a pressure-regulated associated gas. In addition, the system comprises a gas cleaner including a gas inlet in fluid communication with the outlet of the gas compressor, a fuel gas outlet, and a waste product outlet. The gas cleaner separates at least a portion of the sulfur and the water from the associated gas to produce a fuel gas. Further, the system comprises a gas turbine including a fuel gas inlet in fluid communication with the fuel gas outlet of the gas cleaner and an air inlet. Still further, the system comprises a choke in fluid communication with the air inlet.

  16. Overview of emerging control technologies for treating VOC emissions

    SciTech Connect

    Traister, M.; Hamel, T.M.

    1996-12-31

    An increasingly competitive global marketplace has prompted industries worldwide to seek out new and more cost-effective ways of doing business. These economic forces have collided with increasingly stringent environmental regulations to produce a myriad of environmental technologies. For instance, the 1990 Clean Air Act Amendments have placed a significant burden upon American industry to control nearly 200 toxic air contaminants. Clearly, this presents a dynamic marketplace for the development and implementation of new air emission control technologies. This paper presents an overview of four such technologies: high-energy corona discharge; biofiltration; steam reforming; and membrane separation and discusses the potential applications and operational considerations associated with each technology. Each technology has its own niche, depending on the contaminants to be controlled and other factors such as the volume of air to be treated, regulatory requirements for destruction, and space availability. These practical considerations are the focus of how these emerging technologies may provide industry with more efficient ways of complying with environmental mandates. 14 refs., 4 figs., 3 tabs.

  17. Condensing economizers for thermal efficiency improvements and emissions control

    SciTech Connect

    Heaphy, J.P.; Carbonara, J.; Litzke, W.; Butcher, T.A.

    1993-12-31

    Flue gas condensing economizers improve the thermal efficiency of boilers by recovering sensible heat and water vapor latent heat from flue gas exhaust. In addition to improving thermal efficiency, condensing economizers also have the potential to act as control devices for emissions of particulates, SO{sub x}, and air toxics. Both Consolidated Edison of New York and Brookhaven National LaborAtory are currently working on condensing economizer technology with an emphasis on developing their potential for emissions control. Con Edison is currently conducting a condensing economizer demonstration at their oil-fired 74th Street Station in New York. Since installing this equipment in February of 1992 a heat rate improvement of 800 Btu/kWh has been seen. At another location, Ravenswood Station, a two stage condensing economizer has been installed in a pilot test. In this advanced configuration -the ``Integrated Flue Gas Treatment or IFGT system- two heat exchanger sections are installed and sprays of water with and without SO{sub 2} sorbents are included. Detailed studies of the removal of particulates, SO{sub 2}, SO{sub 3}, and selected air toxics have been done for a variety of operating conditions. Removal efficiencies for SO{sub 2} have been over 98% and for SO{sub 3} over 65%. Brookhaven National Laboratory`s studies involve predicting and enhancing particulate capture in condensing economizers with an emphasis on small, coal-fired applications. This work is funded by the Pittsburgh Energy Technology Center of the Department of Energy. Flyash capture efficiencies as high as 97% have been achieved to date with a single stage economizer.

  18. Landfill aeration for emission control before and during landfill mining.

    PubMed

    Raga, Roberto; Cossu, Raffaello; Heerenklage, Joern; Pivato, Alberto; Ritzkowski, Marco

    2015-12-01

    The landfill of Modena, in northern Italy, is now crossed by the new high velocity railway line connecting Milan and Bologna. Waste was completely removed from a part of the landfill and a trench for the train line was built. With the aim of facilitating excavation and further disposal of the material extracted, suitable measures were defined. In order to prevent undesired emissions into the excavation area, the aerobic in situ stabilisation by means of the Airflow technology took place before and during the Landfill Mining. Specific project features involved the pneumatic leachate extraction from the aeration wells (to keep the leachate table low inside the landfill and increase the volume of waste available for air migration) and the controlled moisture addition into a limited zone, for a preliminary evaluation of the effects on process enhancement. Waste and leachate were periodically sampled in the landfill during the aeration before the excavation, for quality assessment over time; the evolution of biogas composition in the landfill body and in the extraction system for different plant set-ups during the project was monitored, with specific focus on uncontrolled migration into the excavation area. Waste biological stability significantly increased during the aeration (waste respiration index dropped to 33% of the initial value after six months). Leachate head decreased from 4 to 1.5m; leachate recirculation tests proved the beneficial effects of moisture addition on temperature control, without hampering waste aerobization. Proper management of the aeration plant enabled the minimization of uncontrolled biogas emissions into the excavation area. PMID:26445364

  19. Dynamics of non-Controlled Emission of Biogas From Landfills

    NASA Astrophysics Data System (ADS)

    Lima, R.; Salazar, J.; Hernandez, P.; Perez, N.

    2001-12-01

    Landfills are important sources of CH4 and CO2 as well as other toxic gas components to the atmosphere. A significant amount of gases could be released to the surrounding environment as a "non-controlled" emission in a diffuse form. To understand the dynamics of non-controlled emission of biogas from landfills several soil gas and CO2 efflux surveys were performed at Arico's landfill (Tenerife, Canary Islands). Estimated diffuse CO2 emission for Arico's landfill (0.33 Km2) were 507 td-1 (1998) and 131 td-1 (2000), showing different spatial CO2 efflux patterns that can be explained in terms of new waste disposal and covering materials as well as the action of the biogas extraction system. Secular variations of diffuse CO2 efflux and meteorological and soil variables were measured hourly at one site in the center of the landfill for 11 months. Diffuse CO2 efflux ranged from 9.9 to 433.3 gm-2d^{-1} with a median value of 242.7 \\pm 73.3 gm^{-2}d-1. Diffuse CO2 efflux showed a temporal behavior that could be divided in two different periods: (a) a quasi-stationary period with minor fluctuations due to the influence of meteorological and soil variables, and (b) a non-stationary period with changing CO2 efflux level and major variations related to the preliminary tests on the biogas extraction system for Arico's landfill. Air and ground temperatures exhibit significant positive correlation with the observed CO2 efflux. Peaks of maximum inverse correlation between barometric pressure and CO2 efflux are found at semi-diurnal and diurnal frequencies. Wind speed and wind direction are cross-correlated with CO2 efflux by 12 hours. These results suggest that (i) minor fluctuations in the CO2 efflux could be driven by meteorological variations (solar radiation cycles and local wind patterns), and (ii) sudden and major fluctuations in the CO2 efflux cannot be explained sufficiently in terms of the observed meteorological and soil variables' fluctuations.

  20. The Effect of Pleural Abrasion on the Treatment of Primary Spontaneous Pneumothorax: A Systematic Review of Randomized Controlled Trials

    PubMed Central

    Ming, Mo-yu; Cai, Shuang-qi; Chen, Yi-Qiang

    2015-01-01

    Background Pleural abrasion has been widely used to control the recurrence of primary spontaneous pneumothorax (PSP). However, controversy still exists regarding the advantages and disadvantages of pleural abrasion compared with other interventions in preventing the recurrence of PSP. Methods The PubMed, Embase, and Cochrane Central Register of Controlled Trials databases were searched up to December 15, 2014 to identify randomized controlled trials (RCTs) that compared the effects of pleural abrasion with those of other interventions in the treatment of PSP. The study outcomes included the PSP recurrence rate and the occurrence rate of adverse effects. Results Mechanical pleural abrasion and apical pleurectomy after thoracoscopic stapled bullectomy exhibited similarly persistent postoperative air leak occurrence rates (p = 0.978) and 1-year PSP recurrence rates (p = 0.821), whereas pleural abrasion led to reduced residual chest pain and discomfort (p = 0.001) and a smaller rate of hemothorax (p = 0.036) than did apical pleurectomy. However, the addition of minocycline pleurodesis to pleural abrasion did not reduce the pneumothorax recurrence rate compared with apical pleurectomy (3.8% for both procedures) but was associated with fewer complications. There was no statistical difference in the pneumothorax recurrence rate between mechanical pleural abrasion and chemical pleurodesis with minocycline on either an intention-to-treat basis (4 of 42 versus 0 of 42, p = 0.12; Fisher exact test) or after exclusions (2 of 40 versus 0 of 42, p = 0.24; Fisher exact test). Pleural abrasion plus minocycline pleurodesis also did not reduce the pneumothorax recurrence rate compared with pleural abrasion alone (p = 0.055). Moreover, pleural abrasion plus minocycline pleurodesis was associated with more intense acute chest pain. The postoperative overall recurrence rate in patients who underwent staple line coverage with absorbable cellulose mesh and fibrin glue was similar to that with mechanical abrasion after thoracoscopic bullectomy (13.8% vs. 14.2%, respectively; p = 0.555), but staple line coverage resulted in less postoperative residual pain than mechanical abrasion (0.4% vs.3.2%; p<0.0001). Pleural abrasion after thoracoscopic wedge resection did not decrease the recurrence of pneumothorax compared with wedge resection alone (p = 0.791), but the intraoperative bleeding and postoperative pleural drainage rates were higher when pleural abrasion was performed. Conclusions In addition to resulting in the same pneumothorax recurrence rate, thoracoscopic pleural abrasion with or without minocycline pleurodesis is safer than apical pleurectomy in the treatment of PSP. However, minocycline pleurodesis with or without pleural abrasion is not any more effective than pleural abrasion alone. Moreover, additional mechanical abrasion is not safer than additional staple line coverage with absorbable cellulose mesh and fibrin glue after thoracoscopic bullectomy because of increased postoperative pain. Additionally, pleural abrasion after thoracoscopic wedge resection should not be recommended for routine application due to the greater incidence of adverse effects than wedge resection alone. However, further large-scale, well-designed RCTs are needed to confirm the best procedure. PMID:26042737