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1

Coherent control of spontaneous emission near a photonic band edge  

Microsoft Academic Search

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

Mesfin Woldeyohannes; Sajeev John

2003-01-01

2

Controlling spontaneous emission with plasmonic optical patch antennas.  

PubMed

We experimentally demonstrate the control of the spontaneous emission rate and the radiation pattern of colloidal quantum dots deterministically positioned in a plasmonic patch antenna. The antenna consists of a thin gold microdisk separated from a planar gold layer by a few tens of nanometers thick dielectric layer. The emitters are shown to radiate through the entire patch antenna in a highly directional and vertical radiation pattern. Strong acceleration of spontaneous emission is observed, depending on the antenna geometry. Considering the double dipole structure of the emitters, this corresponds to a Purcell factor up to 80 for dipoles perpendicular to the disk. PMID:23461679

Belacel, C; Habert, B; Bigourdan, F; Marquier, F; Hugonin, J-P; de Vasconcellos, S Michaelis; Lafosse, X; Coolen, L; Schwob, C; Javaux, C; Dubertret, B; Greffet, J-J; Senellart, P; Maitre, A

2013-03-12

3

Spontaneous emission control in a tunable hybrid photonic system.  

PubMed

We experimentally demonstrate control of the rate of spontaneous emission in a tunable hybrid photonic system that consists of two canonical building blocks for spontaneous emission control, an optical antenna and a mirror, each providing a modification of the local density of optical states (LDOS). We couple fluorophores to a plasmonic antenna to create a superemitter with an enhanced decay rate. In a superemitter analog of the seminal Drexhage experiment we probe the LDOS of a nanomechanically approached mirror. Because of the electrodynamic interaction of the antenna with its own mirror image, the superemitter traces the inverse of the LDOS enhancement provided by the mirror, in stark contrast to a bare source, whose decay rate is proportional to the mirror LDOS. PMID:23745934

Frimmer, Martin; Koenderink, A Femius

2013-05-23

4

Spontaneous Emission Control in a Tunable Hybrid Photonic System  

NASA Astrophysics Data System (ADS)

We experimentally demonstrate control of the rate of spontaneous emission in a tunable hybrid photonic system that consists of two canonical building blocks for spontaneous emission control, an optical antenna and a mirror, each providing a modification of the local density of optical states (LDOS). We couple fluorophores to a plasmonic antenna to create a superemitter with an enhanced decay rate. In a superemitter analog of the seminal Drexhage experiment we probe the LDOS of a nanomechanically approached mirror. Because of the electrodynamic interaction of the antenna with its own mirror image, the superemitter traces the inverse of the LDOS enhancement provided by the mirror, in stark contrast to a bare source, whose decay rate is proportional to the mirror LDOS.

Frimmer, Martin; Koenderink, A. Femius

2013-05-01

5

Spontaneous emission lifetimes of infrared quantum dots controlled with photonic crystals  

Microsoft Academic Search

The spontaneous emission decay rate of light sources is determined both by intrinsic properties of the emitter, and by the Local Density of Optical States (LDOS). Spontaneous emission control is relevant for light-matter interaction studies, vacuum field engineering, in the areas of telecommunication and quantum computing. Control over the spontaneous emission decay rate can be used to make efficient light

Bart H. Husken; Willem L. Vos

2009-01-01

6

Controllable enhancement of spontaneous emission in perpendicular direction by single quantum well embedded in planar microcavities  

Microsoft Academic Search

Based on the cavity quantum electrodynamics, the controllable enhancement of spontaneous emission in perpendicular direction by single quantum well embedded in a planar micro-cavity has been studied. The spontaneous emission spectra are obtained for different mirror reflectivity and cavity length when the carrier density is fixed. The results show that the spontaneous emission intensity can be enhanced by increasing the

Hongdong Zhao; Guangdi Shen; Tao Yin; Changhua Chen; Zuntu Xu; Peng Lian; Guo Gao; Shiming Lin

1998-01-01

7

Controlled spontaneous emission in plasmonic whispering gallery antennas  

NASA Astrophysics Data System (ADS)

We present a plasmonic whispering gallery nanoantenna doped with an ATTO680 dye that shows cavity-modified spontaneous emission. The plasmonic ring antenna consists of a circular groove cavity in a single-crystal Au surface that sustains resonances with different azimuthal and radial mode order. We observe spectral reshaping of the dye emission that can be tuned over a broad band by varying the cavity resonance conditions.

Vesseur, Ernst Jan R.; Polman, Albert

2011-12-01

8

White light emission on amplified spontaneous emission with dye content controlled polymer system  

NASA Astrophysics Data System (ADS)

White light emission from amplified spontaneous emission (ASE) was realized by optically pumping fluorescent dye 4-(dicy-anomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped semiconducting poly(9,9-dioctylfluorene) (PFO) polymer thin films. Two individual ASE peaks originating from DCJTB and PFO were observed by carefully controlling the DCJTB concentration in PFO. The studies of the ASE characteristics of DCJTB:PFO thin films lead to the conclusion that the DCJTB:PFO system with 0.3% w/w DCJTB dopant concentration in PFO showed the best ASE performance. In the DCJTB:PFO system with 0.3% w/w DCJTB dopant concentration, the net gains, loss coefficients, and threshold reached 36.3 and 22.35 cm-1, 7.39 and 15.88 cm-1, and 0.072 and 0.035 mJ pulse-1, for DCJTB emission and PFO emission, respectively. Our results predict an approach to achieve white light emission through amplified spontaneous emission in host polymer systems via controlled dye content.

Zhang, Dingke; Chen, Zhenyu; Ma, Dongge

2008-06-01

9

Controlling the dynamics of spontaneous emission from quantum dots by photonic crystals  

Microsoft Academic Search

Control of spontaneously emitted light lies at the heart of quantum optics. It is essential for diverse applications ranging from miniature lasers and light-emitting diodes, to single-photon sources for quantum information, and to solar energy harvesting. To explore such new quantum optics applications, a suitably tailored dielectric environment is required in which the vacuum fluctuations that control spontaneous emission can

Peter Lohdahl; A. Floris van Driel; Ivan S. Nikolaev; Arie Irman; Karin Overgaag; Daniël Vanmaekelbergh; Willem L. Vos

2004-01-01

10

Control of spontaneous emission in InGaAs\\/GaAs quantum structure lattices  

Microsoft Academic Search

We report the control of spontaneous emission wavelength of quantum wells (QWs) using an artificial design of semiconductor lattice, i.e., quantum structure lattice (QSL). Two-dimension square quantum box arrays fabricated in strained InGaAs\\/GaAs QW samples are used as active lattice units in QSL for this study. The photoluminescence peak wavelength of the QSL can be adjusted to blue-shift, red-shift, or

K. Y. Cheng; Chien-Chia Cheng; K. C. Hsieh

2011-01-01

11

Control of spontaneous emission in InGaAs/GaAs quantum structure lattices  

NASA Astrophysics Data System (ADS)

We report the control of spontaneous emission wavelength of quantum wells (QWs) using an artificial design of semiconductor lattice, i.e., quantum structure lattice (QSL). Two-dimension square quantum box arrays fabricated in strained InGaAs/GaAs QW samples are used as active lattice units in QSL for this study. The photoluminescence peak wavelength of the QSL can be adjusted to blue-shift, red-shift, or unchanged from that of the as-grown QW by fitting the in-plane Bragg diffraction condition of the QSL. The wavelength-shift has values of multiple phonon energies indicating that the phonon-assisted recombination process may play a significant role in the observed spontaneous emission.

Cheng, K. Y.; Cheng, Chien-Chia; Hsieh, K. C.

2011-10-01

12

X-ray Spontaneous Emission Control By 1D-PBG Structure  

SciTech Connect

The control of the decay rate of an excited atom through the photonic mode density (PMD) was pointed out at radiofrequency by Purcell in 1946. Nowadays the development of sophisticated photonic band structures makes it possible to monitor the PMD at shorter radiation wavelengths and then to manipulate the spontaneous emission of atoms in the hard region of the electromagnetic spectrum especially in the visible domain. In this communication we study the possibility of monitoring the x-ray emission by means of one-dimensional photonic band structures such as periodic multilayer systems. Enhancement or inhibition of soft x-ray emissions seems now to be feasible by means of the state-of-the art in x-ray optics.

Andre, Jean-Michel; Jonnard, Philippe [Laboratoire de Chimie Physique-Matiere et Rayonnement, CNRS, Universite Paris 6, UMR 7614, 11 rue Pierre et Marie Curie, F-75231 Paris CEDEX 05 (France)

2010-04-06

13

X-ray Spontaneous Emission Control By 1D-PBG Structure  

NASA Astrophysics Data System (ADS)

The control of the decay rate of an excited atom through the photonic mode density (PMD) was pointed out at radiofrequency by Purcell in 1946. Nowadays the development of sophisticated photonic band structures makes it possible to monitor the PMD at shorter radiation wavelengths and then to manipulate the spontaneous emission of atoms in the hard region of the electromagnetic spectrum especially in the visible domain. In this communication we study the possibility of monitoring the x-ray emission by means of one-dimensional photonic band structures such as periodic multilayer systems. Enhancement or inhibition of soft x-ray emissions seems now to be feasible by means of the state-of-the art in x-ray optics.

André, Jean-Michel; Jonnard, Philippe

2010-04-01

14

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

PubMed

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

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

2012-12-27

15

Coherent Control of Spontaneous Emission near a Photonic Band Edge: A Single-Atom Optical Memory Device  

NASA Astrophysics Data System (ADS)

We demonstrate coherent control of spontaneous emission from a three-level atom with one resonant frequency near the edge of a photonic band gap. As a result of quantum interference and photon localization, spontaneous emission can be totally suppressed or strongly enhanced depending on the relative phase between the control and pump laser fields. The fractionalized steady state inversion of the atom depends sensitively on the initial conditions, suggesting the possibility of a phase-sensitive, optical memory device on the atomic scale.

Quang, Tran; Woldeyohannes, Mesfin; John, Sajeev; Agarwal, Girish S.

1997-12-01

16

Evidence for Confined Tamm Plasmon Modes under Metallic Microdisks and Application to the Control of Spontaneous Optical Emission  

NASA Astrophysics Data System (ADS)

We demonstrate strong confinement of the optical field by depositing a micron sized metallic disk on a planar distributed Bragg reflector. Confined Tamm plasmon modes are evidenced both experimentally and theoretically, with a lateral confinement limited to the disk area and strong coupling to TE polarized fields. Single quantum dots controllably coupled to these modes are shown to experience acceleration of their spontaneous emission when spectrally resonant with the mode. For quantum dots spectrally detuned from the confined Tamm plasmon mode, an inhibition of spontaneous emission by a factor 40±4 is observed, a record value in the optical domain.

Gazzano, O.; de Vasconcellos, S. Michaelis; Gauthron, K.; Symonds, C.; Bloch, J.; Voisin, P.; Bellessa, J.; Lemaître, A.; Senellart, P.

2011-12-01

17

Control of spontaneous emission spectra and simulation of multiple spontaneously generated coherence in a four-level atomic system  

NASA Astrophysics Data System (ADS)

We investigate the fluorescence spectrum for a four-level atomic system, three levels of which are coupled with two laser fields in a ladder configuration, and the upper-most level decays to the fourth level via spontaneous emission. The results show that a few interesting phenomena such as spectral-line narrowing, spectral-line enhancement, spectral-line suppression, and spontaneous emission quenching can be realized in our system and can be manipulated via adjusting the proper parameters. It is found that, in the dressed-state picture, this system is equivalent to the system with multiple spontaneously generated coherence studied by Joshi et al. [A. Joshi, W. Yang, M. Xiao, Phys. Lett. A 325 (2004) 30].PACS42.50.Gy32.80.Qk32.50.+dKeywordsSpontaneous emission spectraMultiple spontaneously generated coherenceDressed state pictureReferencesS.Y.ZhuL.M.NarducciM.O.ScullyPhys. Rev. A5219954791S.Y.ZhuR.C.F.ChanC.P.LeePhys. Rev. A521995710S.Y.ZhuH.ChenH.HuangPhys. Rev. Lett.791997205S.JohnT.QuangPhys. Rev. Lett.7819971888P.ZhouS.SwainPhys. Rev. A551997772H.HuangS.Y.ZhuM.S.ZubairyPhys. Rev. A551997744Y.WuPhys. Rev. A612000033803Y.WuP.T.LeungPhys. Rev. A601999630Y.WuX.YangP.T.LeungOpt. Lett.241999345C.H.KeitelP.L.KnightL.M.NarducciM.O.ScullyOpt. Commun.1181995143F.GhafoorS.Y.ZhuM.S.ZubairyPhys. Rev. A622000013811E.PaspalakisC.H.KeitelP.L.KnightPhys. Rev. A5819984868E.PaspalakisP.L.KnightPhys. Rev. Lett.811998293K.T.KapaleM.O.ScullyS.Y.ZhuM.S.ZubairyPhys. Rev. A672003023804M.A.AntónO.G.CalderónF.CarreñoPhys. Rev. A722005023809X.M.HuJ.S.PengJ. Phys. B: At. Mol. Opt. Phys.332000921H.LeeP.PolynkinM.O.ScullyS.Y.ZhuPhys. Rev. A5519974454S.Y.ZhuM.O.ScullyPhys. Rev. Lett.761996388P.R.BermanPhys. Rev. A5819984886P.ZhouS.SwainPhys. Rev. Lett.781997832C.H.KeitelPhys. Rev. Lett.8319991307T.HongC.CramerW.NagourneyE.N.FortsonPhys. Rev. Lett.942005050801F.GhafoorS.QamarM.S.ZubairyPhys. Rev. A652002043819M.A.G.MartinezP.R.HerczfeldC.SamuelsL.M.NarducciC.H.KeitelPhys. Rev. A5519974483G.S.AgarwalPhys. Rev. Lett.671991980A.S.ZibrovM.D.LukinD.E.NikonovL.HollbergM.O.ScullyV.L.VelichanskyH.G.RobinsonPhys. Rev. Lett.7519951499S.E.HarrisPhys. Rev. Lett.6219891033J.Y.GaoC.GuoX.Z.GuoG.X.JinQ.W.WangJ.ZhaoH.Z.ZhangY.JiangD.Z.WangD.M.JiangOpt. Commun.931992323M.O.ScullyM.FleischhauerPhys. Rev. Lett.6919921360M.FleischhauerA.B.MatskoM.O.ScullyPhys. Rev. A622000013808T.HongC.CramerW.NagourneyE.N.FortsonPhys. Rev. Lett.942005050801M.O.ScullyPhys. Rev. Lett.6719911855M.FleischhauerC.H.KeitelM.O.ScullyC.SuB.T.UlrichS.Y.ZhuPhys. Rev. A4619921468C.H.BennettD.P.DivincenzoNature4042000247D.PetrosyanY.P.MalakyanPhys. Rev. A702004023822M.PaternostroM.S.KimP.L.KnightPhys. Rev. A712005022311E.ArimondoE.WolfProgress in Optics1996ElsevierAmsterdam257G.S.AgarwalQuantum Optics1974Springer-VerlagBerlinJ.JavanainenEurophys. Lett.171992407A.FountoulakisA.F.TerzisE.PaspalakisPhys. Rev. A732006033811S.MenonG.S.AgarwalPhys. Rev. A611999013807W.HarshawardhanG.S.AgarwalPhys. Rev. A581998598O.KocharovskayaA.B.MatskoY.RostovtsevPhys. Rev. A652001013803S.MenonG.S.AgarwalPhys. Rev. A5719984014G.X.LiF.L.LiS.Y.ZhuPhys. Rev. A642001013819For early work on this subject, see alsoG.S.AgarwalPhys. Rev. Lett.8420005500J.H.WuA.J.LiY.DingY.C.ZhaoJ.Y.GaoPhys. Rev. A722005023802A.J.LiJ.Y.GaoJ.H.WuL.WangJ. Phys. B: At. Mol. Opt. Phys.3820053815J.H.LiJ.B.LiuA.X.ChenC.C.QiPhys. Rev. A742006033816A.JoshiM.XiaoEur. Phys. J. D352005547A.JoshiW.YangM.XiaoPhys. Lett. A325200430Y.WuX.YangPhys. Rev. A712005053806Y.WuX.YangPhys. Rev. A702004053818Y.WuJ.SaldanaY.ZhuPhys. Rev. A672003013811Y.WuL.WenY.ZhuOpt. Lett.282003631V.WeisskopfE.P.WignerZ. Phys.54193063S.M.BarnettP.M.RadmoreMethods in Theoretical Quantum Optics1997Oxford University PressOxfordWithout loss of generality, we have assumed that the probe field ?p and the coupling field ?c are real in this part.

Li, Jia-Hua; Chen, Ai-Xi; Liu, Ji-Bing; Yang, Xiaoxue

2007-10-01

18

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

NASA Astrophysics Data System (ADS)

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.

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

19

Directional spontaneous emission enhancement in hyperbolic metamaterials  

NASA Astrophysics Data System (ADS)

In this paper, we experimentally demonstrate the control of spontaneous emission enhancement in multilayered Au/Al2O3 hyperbolic metamaterials (HMMs). The hyperbolic dispersion of the Au/Al2O3 multilayers at optical frequencies is confirmed by using effective medium theory, and then the results are validated by experiments performed through variable angle spectroscopic ellipsometry. The modification of spontaneous emission enhancement is observed when the emission wavelengths of different chromophores deposited on top of the multilayer are tuned from the elliptical to hyperbolic spectral region of the HMM. The simulation results further support the modification of spontaneous emission enhancement in designed HMM. This proposed concept and methodology promises potential applications in areas such as single photon sources and biosensing.

Sreekanth, K. V.; Biaglow, T.; Strangi, G.

2013-10-01

20

Inhibited spontaneous emission in solid-state physics and electronics  

Microsoft Academic Search

It has been recognized for some time that the spontaneous emission by atoms is not necessarily a fixed and immutable property of the coupling between matter and space, but that it can be controlled by modification of the properties of the radiation field. This is equally true in the solid state, where spontaneous emission plays a fundamental role in limiting

Eli Yablonovitch

1987-01-01

21

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

SciTech Connect

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.

Jiang, X. Q.; Zhang, B.; Sun, X. D. [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Lu, Z. W. [National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150001 (China)

2011-05-15

22

Controllable diffusion of cold atoms in a harmonically driven and tilted optical lattice: decoherence by spontaneous emission  

Microsoft Academic Search

We have studied some transport properties of cold atoms in an accelerated optical lattice in the presence of decohering effects due to spontaneous emission. One new feature added is the effect of an external ac drive. As a result we obtain a tunable diffusion coefficient and its nonlinear enhancement with increasing drive amplitude. We report an interesting maximum diffusion condition.

Navinder Singh

2008-01-01

23

Spontaneous emission control of CdSe/ZnS nanoparticle monolayer in polymer nanosheet waveguide assembled on a one-dimensional silver grating surface.  

PubMed

We present spontaneous emission control of a core-shell CdSe/ZnS nanoparticle array assembled with polymer ultrathin films consisting of polymer nanosheets on a silver grating substrate, which served as a unique and simple photonic cavity. The grating-coupled waveguide modes enabled 10(3) order luminescence enhancement and one-fourth spectral narrowing. The light emission from a CdSe/ZnS nanoparticle array can be controlled by tuning the film thickness of hybrid polymer nanoassemblies, which provides multiple emission performance with good tuning ability from red to green at low-power continuous wave laser excitation (??W). PMID:22260265

Mitsuishi, Masaya; Morita, Shimpei; Tawa, Keiko; Nishii, Junji; Miyashita, Tokuji

2012-01-23

24

Nonperturbative theory of cavity-controlled spontaneous emission of two-level atom trapped in two crossed cavities  

NASA Astrophysics Data System (ADS)

The time-dependent spontaneous emission spectral line shape of two level motionless atom placed in common antinode of two symmetrically detuned lossless modes has been investigated nonperturbatively. The line shape and its temporal evolution have been found to be a function of modes detuning and natural line width of isolated atom. The spectrum varies between singlet and triplet taking on the well-known Lorentz-shape form when detuning and natural line width become much larger than the coupling constant of interaction of the atom with modes.

Cheltsov, Vladislav F.

1998-08-01

25

Nuclear-spin noise and spontaneous emission  

Microsoft Academic Search

The spontaneous emission from nuclear spins has been observed at liquid-4He temperatures. The spins, 35Cl nuclei, are placed in the inductor of a tuned LCR circuit coupled to a dc superconducting quantum interference device used as a radio-frequency amplifier. When the spins are saturated and have zero polarization, the emission is observed at the nuclear quadrupole Larmor frequency as a

Tycho Sleator; Claude Hilbert; John Clarke

1987-01-01

26

Fast reset and suppressing spontaneous emission of a superconducting qubit  

NASA Astrophysics Data System (ADS)

Spontaneous emission through a coupled cavity can be a significant decay channel for qubits in circuit quantum electrodynamics. We present a circuit design that effectively eliminates spontaneous emission due to the Purcell effect while maintaining strong coupling to a low-Q cavity. Excellent agreement over a wide range in frequency is found between measured qubit relaxation times and the predictions of a circuit model. Using fast (nanosecond time-scale) flux biasing of the qubit, we demonstrate in situ control of qubit lifetime over a factor of 50. We realize qubit reset with 99.9% fidelity in 120 ns.

Reed, M. D.; Johnson, B. R.; Houck, A. A.; Dicarlo, L.; Chow, J. M.; Schuster, D. I.; Frunzio, L.; Schoelkopf, R. J.

2010-05-01

27

Spontaneous lifetime control in a native-oxide-apertured microcavity  

Microsoft Academic Search

Spontaneous lifetime control is demonstrated using very small apertured microcavities, with quantum-dot light emitters used to obtain electronic confinement within the aperture. A factor of 2.3 increase in the averaged spontaneous emission rate is achieved due to the optical confinement. The enhancement\\/inhibition ratio of the spontaneous emission rate tracks the optical mode size and spectral response of the apertured microcavity.

L. A. Graham; D. L. Huffaker; D. G. Deppe

1999-01-01

28

Shaping the Spontaneous Emission Pulse from a Superconducting Qubit  

NASA Astrophysics Data System (ADS)

We report on measurements of spontaneous emission in a circuit quantum electrodynamics system. A superconducting qubit with tunable coupling to a coplanar waveguide cavity is operated in a regime where the qubit relaxation time, and consequently the spontaneous emission rate, is dominated by the interaction strength. This fast control knob on the coupling strength is used to shape the emitted single photon's wavepacket. The independent control over the coupling allows the dressed qubit frequency to remain truly constant during the emission. The wavepacket shape becomes important in experiments where quantum information needs to be transported between various nodes in a quantum network. The transfer can happen with a very high fidelity if the wavepacket is time-symmetric, since emission by the source and absorption by the destination become time reversed processes.

Srinivasan, Srikanth; Liu, Yanbing; Zhang, Gengyan; Yu, Terri; Gambetta, Jay; Girvin, Steven; Houck, Andrew

2013-03-01

29

Enhanced Kerr nonlinearity via quantum interference from spontaneous emission  

NASA Astrophysics Data System (ADS)

A novel atom configuration is proposed for a giant Kerr nonlinearity in zero linear and nonlinear probe absorption. It is shown that without coherent control field and just by quantum interference of spontaneous emission, a giant Kerr nonlinearity can be obtained.

Asadpour, S. H.; Sahrai, M.; Soltani, A.; Hamedi, H. R.

2012-01-01

30

Quenching of spontaneous emission coefficients in plasmas  

SciTech Connect

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.

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

1987-09-01

31

On spontaneous photon emission in collapse models  

NASA Astrophysics Data System (ADS)

We reanalyze the problem of spontaneous photon emission in collapse models. We show that the extra term found by Bassi and Dürr is present for non-white (colored) noise, but its coefficient is proportional to the zero frequency Fourier component of the noise. This leads one to suspect that the extra term is an artifact. When the calculation is repeated with the final electron in a wave packet and with the noise confined to a bounded region, the extra term vanishes in the limit of continuum state normalization. The result obtained by Fu and by Adler and Ramazano?lu from application of the Golden Rule is then recovered.

Adler, Stephen L.; Bassi, Angelo; Donadi, Sandro

2013-06-01

32

Cooperative spontaneous emission of three identical atoms  

NASA Astrophysics Data System (ADS)

We study cooperative single-photon spontaneous emission from three multilevel atoms with one of them being excited for different atomic configurations in optical vector theory. The dynamic evolution is solved by finding the eigenvalues of a 3 × 3 matrix, and then the relevant decay rates and Lamb shifts are obtained analytically. It is shown that the symmetry of atomic configuration has a big influence on the super-radiance of the system. To obtain strong super-radiance requires not only the distances among the three atoms to be much shorter than the wavelength, but also to have symmetrical distribution. We also calculate the emission spectra and find that it normally has three peaks, but it has two peaks under the equilateral-triangle configuration.

Feng, Wei; Li, Yong; Zhu, Shi-Yao

2013-09-01

33

Spontaneous emission near the edge of a photonic band gap  

Microsoft Academic Search

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

Sajeev John; Tran Quang

1994-01-01

34

Spontaneous emission and photon dynamics in dielectric microcavities  

SciTech Connect

We consider spontaneous emission in dielectric microcavities with multiple resonances that may overlap in both position and frequency. By projecting the Green tensor onto a set of quasimodes associated with the resonances, we derive the reduced spontaneous emission rate. To demonstrate the accuracy and computational efficiency of our approach, we model spontaneous emission in a two-dimensional photonic crystal with two coupled defects. Employing a quantum mechanical interpretation, we show that the spontaneous emission involves both direct decay into the individual quasimodes and photon transfer between the quasimodes. The quantum path interference between these different emission channels can cause the spontaneous emission rate to differ dramatically from the rate obtained by the summation over resonant line shapes. We also show how our approach can be used to determine the emission into particular quasimodes of multiple-resonance microcavities.

Fussell, D. P.; Dignam, M. M. [Department of Physics, Queen's University, Kingston, Ontario, K7K 3N6 (Canada); Steel, M. J. [RSoft Design Group, Inc., 65 O'Connor Street, Chippendale, New South Wales 2008 (Australia); Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS), School of Physics, University of Sydney, Sydney 2006 (Australia); Sterke, C. Martijn de; McPhedran, R. C. [Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS), School of Physics, University of Sydney, Sydney 2006 (Australia)

2006-10-15

35

Spontaneous emission from a fractal vacuum  

NASA Astrophysics Data System (ADS)

Spontaneous emission of a quantum emitter coupled to a QED vacuum with a deterministic fractal structure of its spectrum is considered. We show that the decay probability does not follow a Wigner-Weisskopf exponential decrease but rather an overall power law behavior with a rich oscillatory structure, both depending on the local fractal properties of the vacuum spectrum. These results are obtained by giving first a general perturbative derivation for short times. Then we propose a simplified model which retains the main features of a fractal spectrum to establish analytic expressions valid for all time scales. Finally, we discuss the case of a Fibonacci cavity and its experimental relevance to observe these results.

Akkermans, Eric; Gurevich, Evgeni

2013-08-01

36

Manipulation of Spontaneous Emission via Quantum Interference in an Elliptically Polarized Laser Field  

NASA Astrophysics Data System (ADS)

Manipulation of spontaneous emission from an atom confined in three kinds of modified reservoirs has been investigated by means of an elliptically polarized laser field. Some interesting phenomena such as the multi-peak structure, extreme spectral narrowing, and cancellation of spontaneous emission can be observed by adjusting controllable system parameters. Moreover, these phenomena depend on the constructive or destructive quantum interference between multiple decay channels and which can be changed appreciably by varying the phase difference between the two circularly polarized components of the probe field. These results demonstrate the importance of an elliptically polarized laser field in controlling the spontaneous emission and its potential applications in high-precision spectroscopy.

Ding, Chun-Ling; Li, Jia-Hua; Yu, Rong; Zhang, Duo; Yang, Xiao-Xue

2013-05-01

37

Spontaneous otoacoustic emissions in monitor lizards.  

PubMed

Monitors (all of which belong to the genus Varanus) make up a very uniform family of often large lizards. They have a large auditory papilla that is not highly specialized, but is divided into two unequal sub-papillae. All hair cells are covered by a tectorial membrane. Spontaneous otoacoustic emissions (SOAE) were examined in Cape monitor lizards (Varanus exanthematicus) and found between 1.08 and 2.91 kHz (at 32 degrees C) and with levels between -2.8 and 25.8 dB SPL. The frequency of SOAE was temperature dependent, with a maximal shift of 0.07 octaves/degrees C. All SOAE could be suppressed by external tones, most easily by tones near the center frequency and thus suppression tuning curves were V-shaped. In addition, SOAE could be facilitated by external tones, the amplitude increasing up to 10 dB. The most effective tones were generally those between 0.33 and 0.75 octaves above the respective center frequency of the SOAE. External tones could also change the center frequency of SOAE by up to several hundred Hz, most tones causing frequency 'pushing'. Compared to SOAE of other lizards, Varanus SOAE have larger amplitudes and show larger frequency shifts with temperature. Both of these features may be the result of the coupling of large numbers of hair cells via the continuous tectorial membrane. PMID:14987751

Manley, Geoffrey A

2004-03-01

38

The fine structure constant determines spontaneous emission rates from semiconductors  

NASA Astrophysics Data System (ADS)

The probability of spontaneous emission from a semiconductor, per oscillation of the optical field, is proportional to the cube of the fine structure constant ? and the ratio of the semiconductor dipole parameter Ep to hydrogen's Rydberg energy. Expressions for radiative recombination rates in quantum wells and bulk semiconductors are given, including the bimolecular radiative recombination coefficient B. We show that ? sets the natural scale for spectral density of spontaneous emission per square wavelength area of a quantum well. The fine structure constant also sets a physical limit to the Purcell enhancement factor for spontaneous emission.

Szkopek, Thomas

2011-05-01

39

Coherent spontaneous emission and spontaneous phase locking in a free-electron laser  

Microsoft Academic Search

We present measurements that demonstrate the existence of spontaneous coherence between independently generated laser pulses in the FELIX free-electron laser. The experiments show that the interpulse coherence is caused by a high level of coherently enhanced spontaneous emission. We have been able to manipulate the level of interpulse coherence by changing the settings of the electron accelerating system. The shape

H. H. Weits; D. Oepts

1999-01-01

40

Temporal and transverse coherence of self-amplified spontaneous emission  

SciTech Connect

The authors review the coherence properties of the self-amplified spontaneous emission (SASE). Temporally, SASE is similar to the spontaneous undulator radiation except that the spectral bandwidth is about ten times narrower compared with typical undulator radiation. The situation is quite different in the transverse dimension, where SASE is fully coherent.

Kim, K.J.

1997-06-01

41

Modified spontaneous emissions of europium complex in weak PMMA opals.  

PubMed

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

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

2011-09-22

42

Coherent spontaneous emission in high gain free-electron lasers  

Microsoft Academic Search

We investigate finite pulse effects in self-amplified spontaneous emission (SASE), especially the role of coherent spontaneous emission (CSE) in the start and the evolution of the free-electron laser (FEL) process. When the FEL interaction is negligible, we solve the one-dimensional Maxwell equation exactly and clarify the meaning of the slowly varying envelope approximation (SVEA). In the exponential gain regime, we

Zhirong Huang; Kwan-Je Kim

1999-01-01

43

Coherent spontaneous emission in high gain free-electron lasers  

Microsoft Academic Search

The authors investigate finite pulse effects in self-amplified spontaneous emission (SASE), especially the role of coherent spontaneous emission (CSE) in the start and the evolution of the free-electron laser (FEL) process. When the FEL interaction is negligible, they solve the one-dimensional Maxwell equation exactly and clarify the meaning of the slowly varying envelope approximation (SVEA). In the exponential gain regime,

muang

1999-01-01

44

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

SciTech Connect

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.

Nikolaev, Ivan S.; Lodahl, Peter; Vos, Willem L. [Complex Photonic Systems (COPS), Department of Science and Technology, and MESA Institute of Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

2005-05-15

45

Reversible modulation of spontaneous emission by strain in silicon nanowires.  

PubMed

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

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

2012-06-15

46

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

Microsoft Academic Search

Summary form only given. 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

H. Kirkici; J. Kralovec

1995-01-01

47

Spontaneous emission in cavity QED with a terminated waveguide  

NASA Astrophysics Data System (ADS)

We investigate the effects of a nanophotonic boundary on the spontaneous emission properties of an excited two-level atom in cavity quantum electrodynamics (QED) geometry. We show that a boundary provides temporally delayed interference, which can be either constructive or destructive. Consequently, the decay of the atomic excitation can be either increased or greatly inhibited. As a concrete example, we investigate the spontaneous emission process in cavity QED with a terminated line-defect waveguide, and show the rich behavior of the atomic response due to the boundary. We also show that the output photonic wave form is strongly influenced by the boundary.

Bradford, Matthew; Shen, Jung-Tsung

2013-06-01

48

ATOMIC AND MOLECULAR PHYSICS: Spontaneous Emission of a Polarized Atom in a Medium Between Two Parallel Mirrors  

NASA Astrophysics Data System (ADS)

Using the photon closed orbit theory, the spontaneous emission rate of a polarized atom in a medium between two parallel mirrors is derived and calculated. It is found that the spontaneous emission rate of a polarized atom between the mirrors is related to the atomic position and the polarization direction. The results show that in the vicinity of the mirror, the variation of the spontaneous emission rate depends crucially on the atomic polarization direction. With the increase of the polarization angle, the oscillation in the spontaneous emission rate becomes decreased. For the polarization direction parallel to the mirror plane, the oscillation is the greatest; while for the perpendicular polarization direction, the oscillation is nearly vanished. The agreement between our result and the quantum electrodynamics result suggests the correctness of our calculation. This study further verifies that the atomic spontaneous emission process can be effectively controlled by changing the polarization orientation of the atom.

Wang, De-Hua; Huang, Kai-Yun; Xu, Qiang

2010-01-01

49

Spontaneous emission of bound photons from relativistic free electrons  

NASA Astrophysics Data System (ADS)

If the states of photons are bound, another type of spontaneous emission becomes possible for a relativistic electron due to the symmetry breaking in space. We obtain the radiation probability for a relativistic electron passing through a box-shaped cavity. The radiation spectrum is discrete in which line positions are determined by the boundary condition of the cavity.

Nitta, H.; Miyazaki, T.

2002-09-01

50

Spontaneous emission of Weibel fluctuations by anisotropic distributions  

NASA Astrophysics Data System (ADS)

Recently [Yoon, Phys. Plasmas 14, 064504 (2007)], the spontaneous emission of magnetic field fluctuations in isotropic particle distribution functions was investigated. Here, the question is addressed as to how these fluctuations develop for an anisotropic distribution function that supports the Weibel instability. It is shown that, depending on the parameters, either electromagnetic or aperiodic magnetic fluctuations are dominant.

Tautz, R. C.; Schlickeiser, R.

2007-10-01

51

Spatial and spectral characteristics of spontaneous emission in microcylinder LEDs  

Microsoft Academic Search

We have numerically calculated the optical modes of cylindrical microcavity structures enclosed by the lateral boundaries with air, used the calculated values to find the spontaneous emission from strained quantum wells placed in the microcavity and examined the spectral and spatial distribution of the emitted light. We find that microcavity LEDs are capable of producing highly collimated vertical light output

I. Vurgaftman; J. Singh

1995-01-01

52

Casthouse emission control system  

Microsoft Academic Search

During blast furnace casting operations, the hot metal generates fume and particulate emissions. Environmental regulations require that blast furnace casting emissions by controlled. The casthouse of the No. 3 Blast Furnace at USS\\/KOBE in Lorain, Ohio was completely redesigned and rebuilt during the modernization of this facility. A state of the art casthouse emission control system was designed and installed

T. F. Bernarding; K. K. Krol; R. C. Stinson; V. Carson; M. Hahn

1993-01-01

53

Spontaneous emission of the non-Wiener type  

SciTech Connect

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.

Basharov, A. M., E-mail: basharov@gmail.com [Russian Research Centre Kurchatov Institute (Russian Federation)

2011-09-15

54

Generation of squeezed light via spontaneous emission from a three-level cascade system  

Microsoft Academic Search

A theoretical investigation is made into the possibility of generating squeezed states of light in spontaneous emission from a three-level atom. Spontaneous emission is known as a source of the noise which destroys coherence effects. We find that rather than destroy squeezing, spontaneous emission from a three-level cascade system can actually create squeezing in an initially unsqueezed source field provided

M. R Ferguson; Z Ficek; B. J Dalton

1996-01-01

55

Tailoring and enhancing spontaneous two-photon emission using resonant plasmonic nanostructures  

NASA Astrophysics Data System (ADS)

The rate of spontaneous emission is known to depend on the environment of a emitter, and the enhancement of one-photon emission in a resonant cavity is known as the Purcell effect. Here we develop a theory of spontaneous two-photon emission for a general electromagnetic environment including inhomogeneous dispersive and absorptive media. This theory is used to evaluate the two-photon Purcell enhancement in the vicinity of metallic nanoparticles and demonstrates that the surface-plasmon resonances supported by these particles can increase the emission rate by more than two orders of magnitude. The control over two-photon Purcell enhancement given by tailored nanostructured environments could provide an emitter with any desired spectral response and may serve as an ultimate route for designing light sources with novel properties.

Poddubny, Alexander N.; Ginzburg, Pavel; Belov, Pavel A.; Zayats, Anatoly V.; Kivshar, Yuri S.

2012-09-01

56

Atomic dipole traps with Amplified Spontaneous Emission: A proposal  

Microsoft Academic Search

We propose what we believe to be a novel type of optical source for ultra-cold atomic Far Off-Resonance optical-dipole Traps. The source is based on an Erbium Amplified Spontaneous Emission (ASE) source that seeds a high power Erbium Doped Fiber Amplifier. The main interest of this source is its very short coherence length, thus allowing an incoherent superposition of several

Jean-François Clément; Véronique Zehnlé; Jean Claude Garreau; Pascal Szriftgiser

2010-01-01

57

Temperature-induced spontaneous emission of uranyl nitrate hexahydrate  

Microsoft Academic Search

The spectrum of the temperature-induced spontaneous emission (TSE) from uranyl nitrate hexahydrate, UOâ(N-Oâ)â x 6HâO, has been recorded for the first time. It was observed as brilliant spark-like flashes in the temperature range 100-135 K on slow cooling and warming of its crystals. The TSE, as well as photoluminescence, originates from the first excited electronic state (³II\\/sub u\\/) of the

H. D. Bist; T. Nishiya; M. Baba; I. Hanazaki

1988-01-01

58

Self-amplified spontaneous emission for short wavelength coherent radiation  

SciTech Connect

We review the recent progress in our understanding of the self-amplified spontaneous emission (SASE), emphasizing the application to short wavelength generation. Simple formulae are given for the start-up, exponential gain and the saturation of SASE. Accelerator technologies producing high brightness electron beams required for short wavelength SASE are discussed. An example utilizing electron beams from a photocathode-linac system to produce 4nm SASE in the multigigawatt range is presented.

Kim, K.J.; Xie, M.

1992-09-01

59

Spontaneous pion emission as a new natural radioactivity  

NASA Astrophysics Data System (ADS)

In this paper the pionic nuclear radioactivity or spontaneous poin emission by a nucleus from its ground state is investigated. The Q?-values as well as the statistical factors are calculated using the experimental masses tabulated by Wapstra and Audi. Then it was shown that the pionic radioactivity of the nuclear ground state is energetically possible via three-body channels for all nuclides with Z > 80. This new type of natural radioactivity is statistically favored especially for Z = 92 - 106 for which F ?/F SF = 40 - 200 [ MeV] 2. Experimental detection of the neutral pion and also some possible emission mechanisms are discussed.

Ion, D. B.; Ivascu, M.; Ion-Mihai, R.

1986-10-01

60

Bremsstrahlung Emission Accompanying Decays and Spontaneous Fission of Heavy Nuclei  

NASA Astrophysics Data System (ADS)

We present the first results in our study of the bremsstrahlung emission of photons accompanying the spontaneous fission of the 252Cf nucleus. We compare calculations obtained on the basis of our fully quantum model with the experimental data available in literature for photon energies up to about 25 MeV. We find a well agreement between theory and experiment. The results of the bremsstrahlung emission accompanying the ?-decay of the 226Ra nucleus, which has a relevant quadrupole deformation, are also included in the paper.

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

61

Natural noise of laser emission and the effect on it of spontaneous-emission capture  

SciTech Connect

It is shown that the amplitude noise of laser emission cannot be analyzed using the fluctuation--dissipation theorem. The conditions under which this noise is a minimum are determined, and the effect on it of spontaneous-emission capture, which in some cases is decisive, is analyzed.

Golubev, Y.M.; Gryaznevich, V.P.

1985-07-01

62

Quantum theory of spontaneous and stimulated emission of surface plasmons  

SciTech Connect

We introduce a quantization scheme that can be applied to surface waves propagating along a plane interface. An important result is the derivation of the energy of the surface wave for dispersive nonlossy media without invoking any specific model for the dielectric constant. Working in Coulomb's gauge, we use a modal representation of the fields. Each mode can be associated with a quantum harmonic oscillator. We have applied the formalism to derive quantum mechanically the spontaneous emission rate of surface plasmon by a two-level system. The result is in very good agreement with Green's tensor approach in the nonlossy case. Green's approach allows also to account for losses, so that the limitations of a quantum approach of surface plasmons are clearly defined. Finally, the issue of stimulated versus spontaneous emission has been addressed. Because of the increasing density of states near the asymptote of the dispersion relation, it is quantitatively shown that the stimulated emission probability is too small to obtain gain in this frequency region.

Archambault, Alexandre; Marquier, Francois; Greffet, Jean-Jacques; Arnold, Christophe [Laboratoire Charles Fabry, Institut d Optique, CNRS-Univ Paris-Sud, Campus Polytechnique, RD128, 91127 Palaiseau Cedex (France); Laboratoire de Photonique et de Nanostructures, CNRS, Route de Nozay, 91460 Marcoussis (France)

2010-07-15

63

Stack Emission Control  

Microsoft Academic Search

Control of emissions from ceramic processes involves legal consideration, technical evaluation, and engineering procedures in the proper sequence. Combined industrial team effort can result in minimizing and solving air pollution problems.

Michael Bozsin

1971-01-01

64

Casthouse emission control system  

SciTech Connect

During blast furnace casting operations, the hot metal generates fume and particulate emissions. Environmental regulations require that blast furnace casting emissions by controlled. The casthouse of the No. 3 Blast Furnace at USS/KOBE in Lorain, Ohio was completely redesigned and rebuilt during the modernization of this facility. A state of the art casthouse emission control system was designed and installed as an integral part of the casthouse. Casthouse operations and maintenance, and environmental performance were foremost in the design considerations. This paper discusses the design, operations and results of this newly operational system along with some key design issues that were addressed with the EPA. The casthouse emission system as installed and permitted consists of the following: local evacuated hooding above the taphole to capture drilling, plugging and trough emissions near the taphole; a close fitting evacuated trough cover over that portion of the trough that is not covered by local hooding; an evacuated hood over the iron dam and skimmer; close fitting evacuated iron and slag runners covers on the entire length of the iron and slag runner system to capture iron and slag runner emissions; an evacuated enclosure covering the tilting iron spout to capture iron spout emissions; a baghouse operating at not less than 300,000 ACFM during casting operation to collect the captured emissions.

Bernarding, T.F.; Krol, K.K.; Stinson, R.C.; Carson, V.; Hahn, M.

1993-01-01

65

Spontaneous Radiation Emission from Short, High Field Strength Insertion Devices  

SciTech Connect

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.

Geoffrey Krafft

2005-09-15

66

Alpha emission and spontaneous fission through quasi-molecular shapes  

NASA Astrophysics Data System (ADS)

The potential energy governing ? emission has been determined within a liquid drop model including proximity effects between the ? particle and the daughter nucleus and adjusted to reproduce the experimental Q?. The ? emission half-lives have been deduced from the WKB barrier penetration probability as for a spontaneous asymmetric fission. The RMS deviation between the theoretical and experimental values of log 10[T1/2(s)] is only 0.63 for a recent data set of 373 ? emitters and 0.35 for the subset of even-even nuclides. Predictions for the heaviest and superheavy elements are presented as well as simple analytical formulae for log 10[T1/2(s)].

Royer, G.

2000-08-01

67

Non-exponential spontaneous emission dynamics for emitters in a time-dependent optical cavity  

NASA Astrophysics Data System (ADS)

We have theoretically studied the effect of deterministic temporal control of spontaneous emission in a dynamic optical microcavity. We propose a new paradigm in light emission: we envision an ensemble of two-level emitters in an environment where the local density of optical states is modified on a time scale shorter than the decay time. A rate equation model is developed for the excited state population of two-level emitters in a time-dependent environment in the weak coupling regime in quantum electrodynamics. As a realistic experimental system, we consider emitters in a semiconductor microcavity that is switched by free-carrier excitation. We demonstrate that a short temporal increase of the radiative decay rate depletes the excited state and drastically increases the emission intensity during the switch time. The resulting time-dependent spontaneous emission shows a distribution of photon arrival times that strongly deviates from the usual exponential decay: A deterministic burst of photons is spontaneously emitted during the switch event.

Thyrrestrup, Henri; Hartsuiker, Alex; Gérard, Jean-Michel; Vos, Willem L.

2013-10-01

68

Control VOC emissions  

SciTech Connect

Hydrocarbon processing industry (HPI) operators can select volatile organic compound (VOC) reduction programs more cost-effectively using these suggestions. New environmental regulations mandate reducing VOC emissions from process units because of: (1) their potential ozone-producing reactions in the atmosphere and (2) their perceived risk from exposure. Typical VOC sources are: fugitive equipment leaks; loading/transfer operations; wastewater treatment units; storage tanks. In almost all cases, fugitive equipment leaks are the largest source of hydrocarbons and air toxics. In locations with large uncontrolled marine or product-loading facilities, loading emissions may also be high. Costs for implementing these controls are based on the referenced EPA documents and are likely to vary for specific plant conditions and requirements. The challenge facing HPI operators is selecting the most applicable and cost-effective control systems for the specific emission sources. Balancing VOC-emission reductions with capital investment is a complex problem given the many potential paths to achieve compliance. However, these suggestions provide a framework to comprehensively investigate, develop, evaluate (both for capital costs and level of emission control), implement and review results when planning VOC control strategies.

Siegell, J.H. [Exxon Research and Engineering Co., Florham Park, NJ (United States)

1995-08-01

69

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

ERIC Educational Resources Information Center

|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…

Snihur, Adrian W. K.; Hampson, Elizabeth

2011-01-01

70

Continuous-variable entanglement in a correlated spontaneous emission laser  

SciTech Connect

We discuss the generation and evolution of entangled light in a correlated spontaneous emission laser. The master equation for the two-mode field in a cavity is derived and solved analytically. The time-dependent characteristic function in the Wigner representation for the two-mode field is obtained. It shows that the two-mode field in the cavity evolves in a two-mode Gaussian state. The entanglement degree of the two-mode field in the cavity increases initially, then decreases, and finally vanishes as the field evolves from an initial vacuum. The period of the entanglement is extended as the intensity of the driving field is increased. It is found that the entanglement still exists even when the two-mode squeezing disappears. During the entanglement period, the intensity of the field is amplified. The entanglement for the initial field being a two-mode squeezed vacuum and the entanglement of the output field are also discussed.

Tan Huatang [Department of Physics, Hong Kong Baptist University, Hong Kong (China); Department of Physics, Huazhong Normal University, Wuhan (China); Zhu Shiyao [Department of Physics, Hong Kong Baptist University, Hong Kong (China); Zubairy, M. Suhail [Institute for Quantum Studies and Department of Physics, Texas A and M University, Texas 77843-4242 (United States)

2005-08-15

71

Spatial Pauli blocking of spontaneous emission in optical lattices  

SciTech Connect

Spontaneous emission by an excited fermionic atom can be suppressed due to the Pauli exclusion principle if the relevant final states after the decay are already occupied by identical atoms in the ground state. Here we discuss a setup where a single atom is prepared in the first excited state on a single site of an optical lattice under conditions of very tight trapping. We investigate these phenomena in the context of two experimental realizations: (1) with alkali-metal atoms, where the decay rate of the excited state is large, and (2) with alkaline-earth-metal-like atoms, where the decay rate from metastable states can be tuned in experiments. This phenomenon has potential applications towards reservoir engineering and dissipative many-body state preparation in an optical lattice.

Sandner, R. M.; Zoller, P. [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck (Austria); Mueller, M. [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck (Austria); Departamento de Fisica Teorica I, Universidad Complutense, E-28040 Madrid (Spain); Daley, A. J. [Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck (Austria); Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)

2011-10-15

72

Transfer matrix analysis of the amplified spontaneous emission of DFB semiconductor laser amplifiers  

Microsoft Academic Search

Analytical expressions ware derived for the amplified spontaneous emission of a DFB semiconductor laser amplifier with reflective cavity ends. The analysis is extended to a multisection DFB structure including a phase-shifted DFB semiconductor laser amplifier. It is shown that the spontaneous emission power per unit frequency bandwidth emitted from one facet is proportional to the transmission gain and to a

T. Makino; J. Glinski

1988-01-01

73

Enhanced spontaneous emission from GaAs quantum wells in monolithic microcavities  

Microsoft Academic Search

Enhanced spontaneous emission has been observed with wavelength-sized monolithic Fabry–Perot cavities containing GaAs quantum wells. With an on-resonance cavity structure, the photoluminescence intensity increases in the cavity axis direction, and the spontaneous emission lifetime is experimentally found to decrease.

H. Yokoyama; K. Nishi; T. Anan; H. Yamada; S. D. Brorson; E. P. Ippen

1990-01-01

74

Entanglement and nonlocality versus spontaneous emission in two-atom systems  

Microsoft Academic Search

We study evolution of entanglement of two two-level atoms in the presence of dissipation caused by spontaneous emission. We find explicit formulas for the amount of entanglement as a function of time, in the case of destruction of the initial entanglement and possible creation of a transient entanglement between atoms. We also discuss how spontaneous emission influences nonlocality of states

L. Jakóbczyk; A. Jamróz

2003-01-01

75

Prompt Neutron Emission in 252CF Spontaneous Fission  

NASA Astrophysics Data System (ADS)

The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics. The goal was to compare the results from digital data acquisition and digital signal processing analysis with results of the pioneering work of Budtz-Jørgensen and Knitter. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 107 fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The results are in very good agreement with literature. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

Hambsch, F.-J.; Oberstedt, S.; Zeynalov, Sh.

2011-10-01

76

Temperature-induced spontaneous emission of uranyl nitrate hexahydrate  

SciTech Connect

The spectrum of the temperature-induced spontaneous emission (TSE) from uranyl nitrate hexahydrate, UO/sub 2/(N-O/sub 3/)/sub 2/ x 6H/sub 2/O, has been recorded for the first time. It was observed as brilliant spark-like flashes in the temperature range 100-135 K on slow cooling and warming of its crystals. The TSE, as well as photoluminescence, originates from the first excited electronic state (/sup 3/II/sub u/) of the uranyl ion. Each TSE pulse is accompanied by a pulsed electric charge generation between two surfaces of a single crystal. The pulsed charge appears with opposite signs for cooling and warming processes, and in good correlation with the TSE pulse. It is suggested that the internal strain formed in a crystal during the cooling and warming processes causes microcracks, which lead to irregular transient pulses of both TSE and charge generation. The mechanism of excitation of TSE is discussed in detail.

Bist, H.D.; Nishiya, T.; Baba, M.; Hanazaki, I.

1988-05-11

77

Vacuum field energy and spontaneous emission in anomalously dispersive cavities  

SciTech Connect

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.

Bradshaw, Douglas H.; Di Rosa, Michael D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2011-05-15

78

Linac-based, intense, coherent x-ray source using self-amplified spontaneous emission  

SciTech Connect

In this article, the author discusses the principles of self-amplified spontaneous emission (SASE), how the SASE could be the basis of next generation light sources exceeding the current performance -- by many orders of magnitude in spectral brightness, and by a factor of a hundred in time resolution. He also discusses how the SLAC linac, due to its high energy and its precision control, is ideally suited for the x-ray SASE. Therefore, using the SLAC linac for generation of x-ray SASE for the frontier of the photon sciences will ensure that the SLAC linac remain scientifically vigorous for a long time.

Kim, K.J.

1997-09-01

79

Emission of alpha particles during the spontaneous fission of 244Pu  

NASA Astrophysics Data System (ADS)

We have measured the light charged particle (LCP) emission probabililty for the spontaneous fission of 244Pu. For the LCP emission to binary fission probability ratio a value of (2.96+/-0.31)×10-3 was found. This result is in agreement with the previously observed trends concerning the LCP emission probability.

Verboven, M.; Jacobs, E.; de Frenne, D.; Thierens, H.; D'hondt, P.

1994-03-01

80

Amplified spontaneous emission and efficient tunable laser emission from a substituted thiophene-based oligomer  

NASA Astrophysics Data System (ADS)

We investigated gain and lasing in spin-coated films of a soluble substituted oligothiophene. With increasing excitation power, the photoluminescence spectra show a clear line narrowing due to amplified spontaneous emission. We measure a low threshold (20 muJ cm-2) for line narrowing and a large gain cross section (6 x10-16 cm2), indicating that this molecule is a promising active material for organic solid-state lasers. As a demonstrator, we realize a transverse electromagnetic (TEM00) single-mode laser with tunable emission from the yellow to the red (a range of 37 nm), with a pump threshold as low as 18 muJ cm-2 and efficiency of 1.9%. These results are among the best so far reported for organic lasers.

Pisignano, Dario; Anni, Marco; Gigli, Giuseppe; Cingolani, Roberto; Zavelani-Rossi, Margherita; Lanzani, Guglielmo; Barbarella, Giovanna; Favaretto, Laura

2002-11-01

81

UV emission of I2 from the ion-pair state following amplified spontaneous emission  

NASA Astrophysics Data System (ADS)

This paper reports the results of processes resulting in D0u+-X 1?g+ emission when a single rovibrational level of the E0g+ state is prepared. Our study reveals that two kinds of processes populate the D0u+ state; which one occurs depends on the experimental conditions. One process involves amplified spontaneous emission from the E0g+ state. The other is collision-induced energy transfer in self-quenching. We distinguish these two processes from the time profiles of fluorescence signals. These processes give completely different vibrational distributions in the D0u+ state from a given rovibrational level of the E0g+ state. The discrepancy between our results and previous results for the E0g+-->D0u+ relaxation is briefly discussed.

Nakano, Yukio; Fujiwara, Hisashi; Fukushima, Masaru; Ishiwata, Takashi

2008-04-01

82

Influence of amplified spontaneous emission on gain lifetime in high-aperture Ti:sapphire amplifiers.  

PubMed

We demonstrate that by lowering gain lifetime, transverse amplified spontaneous emission imposes practical limit on usable aspect ratio of large-aperture amplifiers in a high-energy Ti:sapphire system. PMID:23670763

Yanovsky, Victor; Krushelnick, Karl

2013-04-10

83

Calculations of the self-amplified spontaneous emission performance of a free-electron laser.  

National Technical Information Service (NTIS)

The linear integral equation based computer code (RON: Roger Oleg Nikolai), which was recently developed at Argonne National Laboratory, was used to calculate the self-amplified spontaneous emission (SASE) performance of the free-electron laser (FEL) bein...

R. Dejus

1999-01-01

84

Entanglement and nonlocality versus spontaneous emission in two-atom system  

Microsoft Academic Search

We study evolution of entanglement of two two-level atoms in the presence of\\u000adissipation caused by spontaneous emission. We find explicit fromulas for the\\u000aamount of entanglement as a function of time, in the case of destruction of the\\u000ainitial entanglement and possible creation of a transient entanglement between\\u000aatoms. We also discuss how spontaneous emission influences nonlocality of\\u000astates

L. Jakobczyk; A. Jamroz

2003-01-01

85

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

NASA Astrophysics Data System (ADS)

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.

Goldberg, David; Menon, Vinod M.

2013-02-01

86

Advanced Emissions Control Development Program  

SciTech Connect

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.

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

2001-03-31

87

ADVANCED EMISSIONS CONTROL DEVELOPMENT PROGRAM  

SciTech Connect

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. The project goal is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPs), fabric filters (baghouses), and wet flue gas desulfurization (WFGD) systems. Development work initially concentrated on the capture of trace metals, fine particulate, hydrogen chloride, and hydrogen fluoride. Recent work has focused almost exclusively on the control of mercury emissions.

G.A. Farthing

2001-02-06

88

Measurements and calculations of spontaneous emission of tensile and compressively strained multiple quantum-wells structures  

NASA Astrophysics Data System (ADS)

The characterization of material and structural properties is essential in the development of high-performance optoelectronics devices. The gain and spontaneous emission of semiconductor emitters are intrinsically related, and knowing one determines the other. In this paper, we report on a comparison between the measured and calculated spontaneous emission spectra of complex semiconductor structures that were developed in our laboratory. Transversely emitted spontaneous emission spectra over a wide range of carrier densities have been obtained for GRIN-SCH-MQW InxGa1-xAsyP1-y structures consisting of three tensile and three compressive wells. Information from these measurements and materials parameters were used to estimate carrier density for each well and subsequently used in the calculation of the emission spectra. The theoretical results were obtained by calculating the spontaneous emission rate for each well independently and then by summing over the six wells. We first calculate the band structure from a 6x6 Luttinger-Kohn Hamiltonian and find the spontaneous emission rate using the carrier density obtained from experimental measurements. A comparison between the Markovian (Lorentzian) and non-Markovian (Gaussian) line shape functions is established, considering the bandgap renormalization. We show that the Gaussian broadening function gives better agreement with the experimental data.

Matei, Rodica; Mercure, Philippe; Champagne, Alain; Lestrade, Michel; Maciejko, Romain; Kashyap, Raman

2005-09-01

89

Doubly enhanced spontaneous emission due to increased photon density of states at photonic band edge frequencies.  

PubMed

Double enhancement of spontaneous emission due to increased photon density of states at the emission frequency and the small group velocity of light at the excitation frequency was clearly demonstrated by angle-resolved photoluminescence experiments for dielectric multilayers composed of Ta2O5 and SiO2 with oxygen vacancies as light emitters. Theoretical emission profiles given by the weak modulation approximation agreed well with the experimental observations. PMID:19654722

Kuroda, Keiji; Sawada, Tsutomu; Kuroda, Takashi; Watanabe, Kenji; Sakoda, Kazuaki

2009-07-20

90

Carbon emissions control strategies  

SciTech Connect

This study was undertaken to address a fundamental issue: the cost of slowing climate change. Experts in eight nations were asked to evaluate, using the best economic models available, the prospects for reducing fossil fuel-based carbon emissions in their respective nations. The nations selected as case studies include: the Soviet Union, Poland, the United States, Japan, Hungary, France, the United Kingdom, and Canada. As important contributors to the greenhouse effect, these industrialized nations must find ways to substantially reduce their emissions. This is especially critical given that developing nations' emissions are expected to rise in the coming decades in the search for economic development. Ten papers have been processed separately for inclusion in the appropriate data bases.

Chandler, W.U. (ed.)

1990-01-01

91

Surface-plasmon-induced modification on the spontaneous emission spectrum via subwavelength-confined anisotropic Purcell factor.  

PubMed

The mechanism of using the anisotropic Purcell factor to control the spontaneous emission linewidths in a four-level atom is theoretically demonstrated; if the polarization angle bisector of the two dipole moments lies along the axis of large/small Purcell factor, destructive/constructive interference narrows/widens the fluorescence center spectral lines. Large anisotropy of the Purcell factor, confined in the subwavelength optical mode volume, leads to rapid spectral line narrowing of atom approaching a metallic nanowire, nanoscale line width pulsing following periodically varying decay rates near a periodic metallic nanostructure, and dramatic modification on the spontaneous emission spectrum near a custom-designed resonant plasmon nanostructure. The combined system opens a good perspective for applications in ultracompact active quantum devices. PMID:22512860

Gu, Ying; Wang, Luojia; Ren, Pan; Zhang, Junxiang; Zhang, Tiancai; Martin, Olivier J F; Gong, Qihuang

2012-04-23

92

A model for the relation between stimulus frequency and spontaneous otoacoustic emissions in lizard papillae.  

PubMed

Spontaneous otoacoustic emissions (SOAEs) and stimulus frequency otoacoustic emissions (SFOAEs) have been described from lizard ears. Although there are several models for these systems, none has modeled the characteristics of both of these types of otoacoustic emissions based upon their being derived from hair cells as active oscillators. Data from the ears of two lizard species, one lacking a tectorial membrane and one with a chain of tectorial sallets, as described by Bergevin et al. ["Coupled, active oscillators and lizard otoacoustic emissions," AIP Conf. Proc. 1403, 453 (2008)], are modeled as an array of coupled self-sustained oscillators. The model, originally developed by Vilfan and Duke ["Frequency clustering in spontaneous otoacoustic emissions from a lizard's ear," Biophys. J. 95, 4622-4630 (2008)], well describes both the amplitude and phase characteristics of SFOAEs and the relation between SFOAEs and SOAEs. PMID:23145611

Wit, Hero P; van Dijk, Pim; Manley, Geoffrey A

2012-11-01

93

Broadband amplified spontaneous emission from Er3+-doped single-mode tellurite fibre  

NASA Astrophysics Data System (ADS)

This paper reports on the fabrication and characterization of a newly erbium-doped single-mode tellurite glass-fibre applicable for 1.5-?m optical amplifiers. A very broad erbium amplified spontaneous emission in the range 1450-1650 nm from erbium-doped single-mode tellurite glass-fibre is obtained upon excitation of a 980-nm laser diode. The effects of the length of glass-fibre and the pumping power of laser diode on the amplified spontaneous emission are discussed. The result indicates that the tellurite glass-fibre is a promising candidate for designing fibre-optic amplifiers and lasers.

Chen, Dong-Dan; Zhang, Qin-Yuan; Liu, Yue-Hui; Xu, Shan-Hui; Yang, Zhong-Min; Deng, Zai-De; Jiang, Zhong-Hong

2006-12-01

94

Spontaneous Emission Lifetime of a Single Trapped Ca+ Ion in a High Finesse Cavity  

NASA Astrophysics Data System (ADS)

We investigate the spontaneous emission lifetime of a single trapped 40Ca+ ion placed at different positions in the vacuum standing wave inside a high finesse cavity which is stabilized to the atomic transition. The lifetime is measured by quantum state detection after ?-pulse excitation. The result for the natural lifetime of the D5/2 metastable state of 1161(22)ms agrees, within 1 standard deviation, with the most precise published value. We observe a reduction of the spontaneous emission lifetime of ?15% in the node of the vacuum field.

Kreuter, A.; Becher, C.; Lancaster, G. P.; Mundt, A. B.; Russo, C.; Häffner, H.; Roos, C.; Eschner, J.; Schmidt-Kaler, F.; Blatt, R.

2004-05-01

95

The spontaneous emission of waves by a fast shock wave in a longitudinal magnetic field  

NASA Astrophysics Data System (ADS)

The stability of a fast longitudinal shock wave relative to small disturbances in the discontinuity surface is considered from the standpoint of ideal magnetic hydrodynamics. It is shown that the region of spontaneous wave emission caused by a discontinuity in a plasma with an arbitrary equation of state is determined by the magnetic field and that it expands in relation to the case in ordinary hydrodynamics. It is noted that in a sufficiently strong magnetic field spontaneous wave emission by a discontinuity can occur in an ideal gas whose heat capacity is a constant.

Pimenov, S. F.

1982-07-01

96

Photon statistics of amplified spontaneous emission in a dense wavelength-division multiplexing regime  

NASA Astrophysics Data System (ADS)

The photon statistics of amplified spontaneous emission in the few-modes regime and in single mode, conditions that are typical of dense wavelength-division multiplexing transmission, have been experimentally proved by direct detection. The dependence of the degeneracy factor for the Bose-Einstein distribution on the degree of second-order coherence of light is stated. The theoretical dependence of the number of amplified spontaneous emission modes on the ratio between the optical channel and the detector bandwidths has also been confirmed by experiments, thus quantifying the loss of validity of asymptotic approximations when they are extended to the few-modes regime.

Pietralunga, Silvia M.; Martelli, Paolo; Martinelli, Mario

2003-02-01

97

Photon statistics of amplified spontaneous emission in a dense wavelength-division multiplexing regime.  

PubMed

The photon statistics of amplified spontaneous emission in the few-modes regime and in single mode, conditions that are typical of dense wavelength-division multiplexing transmission, have been experimentally proved by direct detection. The dependence of the degeneracy factor for the Bose-Einstein distribution on the degree of second-order coherence of light is stated. The theoretical dependence of the number of amplified spontaneous emission modes on the ratio between the optical channel and the detector bandwidths has also been confirmed by experiments, thus quantifying the loss of validity of asymptotic approximations when they are extended to the few-modes regime. PMID:12656315

Pietralunga, Silvia M; Martelli, Paolo; Martinelli, Mario

2003-02-01

98

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

NASA Astrophysics Data System (ADS)

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 ?g 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.

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

2013-11-01

99

Immunogenetics of Spontaneous Control of HIV  

PubMed Central

Host genetic variation is presently estimated to account for about one-fourth of the observed differences in control of HIV across infected individuals. Genome-wide association studies have confirmed that polymorphism within the HLA class I locus is the primary host genetic contributor to determining outcome after infection. Here we progress beyond the genetic associations alone to consider the functional explanations for these correlations. In this process, the complex and multidimensional effects of HLA molecules in viral disease become apparent.

Carrington, Mary; Walker, Bruce D.

2013-01-01

100

Interactions between Hair Cells Shape Spontaneous Otoacoustic Emissions in a Model of the Tokay Gecko's Cochlea  

PubMed Central

Background The hearing of tetrapods including humans is enhanced by an active process that amplifies the mechanical inputs associated with sound, sharpens frequency selectivity, and compresses the range of responsiveness. The most striking manifestation of the active process is spontaneous otoacoustic emission, the unprovoked emergence of sound from an ear. Hair cells, the sensory receptors of the inner ear, are known to provide the energy for such emissions; it is unclear, though, how ensembles of such cells collude to power observable emissions. Methodology and Principal Findings We have measured and modeled spontaneous otoacoustic emissions from the ear of the tokay gecko, a convenient experimental subject that produces robust emissions. Using a van der Pol formulation to represent each cluster of hair cells within a tonotopic array, we have examined the factors that influence the cooperative interaction between oscillators. Conclusions and Significance A model that includes viscous interactions between adjacent hair cells fails to produce emissions similar to those observed experimentally. In contrast, elastic coupling yields realistic results, especially if the oscillators near the ends of the array are weakened so as to minimize boundary effects. Introducing stochastic irregularity in the strength of oscillators stabilizes peaks in the spectrum of modeled emissions, further increasing the similarity to the responses of actual ears. Finally, and again in agreement with experimental findings, the inclusion of a pure-tone external stimulus repels the spectral peaks of spontaneous emissions. Our results suggest that elastic coupling between oscillators of slightly differing strength explains several properties of the spontaneous otoacoustic emissions in the gecko.

Gelfand, Michael; Piro, Oreste; Magnasco, Marcelo O.; Hudspeth, A. J.

2010-01-01

101

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

SciTech Connect

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.

Marocico, C. A.; Knoester, J. [Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747 AG Groningen (Netherlands)

2011-11-15

102

Spontaneous emission from two coaxial disks of atoms  

NASA Astrophysics Data System (ADS)

The spontaneous radiation pattern is calculated for two coaxial disks of atoms, separated by a distance L. The atoms are modeled as having J=0 ground states and J=1 excited states. At t=0 the atoms in one disk are excited to their m=1 excited-state sublevels, while the atoms in the second disk can be either in their ground or excited states. The manner in which the atoms in each disk modify the radiation pattern of the atoms in the other disk is described. It is shown, for example, that when the atoms in the second disk are in their ground states, they can still lead to an increase in the signal radiated by the first disk in certain directions. The dependence on the Fresnel number of the radiation pattern is calculated. Moreover, it is shown that analytic expressions can be obtained for the radiation pattern if the disks are replaced by Gaussian density distributions.

Berman, P. R.

2013-10-01

103

Enhanced spontaneous emission of CdSe quantum dots in monolithic II-VI pillar microcavities  

Microsoft Academic Search

The emission properties of CdSe\\/ZnSe quantum dots in ZnSe-based pillar microcavities are studied. All-epitaxial cavities made of ZnSSe and MgS\\/ZnCdSe superlattices with a single quantum-dot sheet embedded have been grown by molecular beam epitaxy. Pillar structures with diameters down to 500 nm have been realized by focused-ion-beam etching. A pronounced enhancement of the spontaneous emission rate of quantum dots coupling

H. Lohmeyer; C. Kruse; K. Sebald; J. Gutowski; D. Hommel

2006-01-01

104

Spontaneous emission lifetime distribution of infinite line antennas in two-dimensional photonic crystals with finite size  

Microsoft Academic Search

The authors calculate the lifetime distribution functions of spontaneous emission from infinite line antennas embedded in two-dimensional disordered photonic crystals with finite size. The calculations indicate the coexistence of both accelerated and inhibited decay processes in disordered photonic crystals with finite size. The decay behavior of the spontaneous emission from infinite line antennas changes significantly by varying factors such as

Xingsheng Xu; Yiquan Wang

2007-01-01

105

Nanoscale plasmonic resonators with high Purcell factor: spontaneous and stimulated emission  

Microsoft Academic Search

Plasmonic nanoparticles with silver cores and silica shells containing Eu fluorophores near the surface have been produced by wet chemistry method and their spontaneous emission properties characterized. Fluorescence amplification and decreased lifetime is interpreted within the Purcell framework which highlights the role of surface plasmon polariton modes of the nanoparticle. These behave as energy-storing resonators, with values of the Q

Ewa M. Goldys; Wei Deng; Nils P. Calander; K. Drozdowicz-Tomsia; Dayong Jin

2011-01-01

106

Novel nanosecond spectral continuum source - high intensity mode-less amplified spontaneous emission  

Microsoft Academic Search

A broadband (up to about 70 nm) amplified spontaneous emission source giving an energy output of several milijoules and the very good spectral continuum has been developed. Its construction is fairly simple, the unit consists of two rectangular 1 cm cuvettes containing suitable dye solutions one of which is pumped by an excimer laser.

Robert Kolos; Jerzy Sepiol

1989-01-01

107

Scalarized photon analysis of spontaneous emission in the uniform magnetic field free-electron laser  

Microsoft Academic Search

The recently developed concept of scalarized photons (formally photons of any polarization) is used to analyze the spontaneous emission in the uniform magnetic field free-electron laser in the microwave spectral region. With the electron beam energy of up to 10 MeV and the uniform magnetic field of up to 4 Tesla, the radiation (occurring with the fundamental and higher harmonic

Josip Soln

1990-01-01

108

Are human spontaneous otoacoustic emissions generated by a chain of coupled nonlinear oscillators?  

PubMed

Spontaneous otoacoustic emissions (SOAEs) are generated by self-sustained cochlear oscillators. Properties of a computational model for a linear array of active oscillators with nearest neighbor coupling are investigated. The model can produce many experimentally well-established properties of SOAEs. PMID:22894214

Wit, Hero P; van Dijk, Pim

2012-08-01

109

Interactions between Hair Cells Shape Spontaneous Otoacoustic Emissions in a Model of the Tokay Gecko's Cochlea  

Microsoft Academic Search

BackgroundThe hearing of tetrapods including humans is enhanced by an active process that amplifies the mechanical inputs associated with sound, sharpens frequency selectivity, and compresses the range of responsiveness. The most striking manifestation of the active process is spontaneous otoacoustic emission, the unprovoked emergence of sound from an ear. Hair cells, the sensory receptors of the inner ear, are known

Michael Gelfand; Oreste Piro; Marcelo O. Magnasco; A. J. Hudspeth; Vladimir Brezina

2010-01-01

110

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

SciTech Connect

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.

Habiger, R.G.K.; Risken, H. (Abteilung fuer Theoretische Physik, Universitaet Ulm, D-7900 Ulm, Federal Republic of Germany (DE)); James, M.; Moss, F. (Department of Physics, University of Missouri at Saint Louis, Saint Louis, Missouri 63121 (USA)); Schleich, W. (Max-Planck-Institut fuer Quantenoptik, D-8046 Garching bei Muenchen, Federal Republic of Germany (DE) Center for Advanced Studies and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 (USA))

1990-04-01

111

Advanced Emissions Control Development Program  

SciTech Connect

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.

M. J. Holmes

1998-12-03

112

Advanced Emissions Control Development Program  

SciTech Connect

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.

A. P. Evans

1998-12-03

113

Advanced Emissions Control Development Program  

SciTech Connect

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.

A. P. Evans

1998-12-03

114

Electrically controllable spontaneous magnetism in nanoscale mixed phase multiferroics.  

PubMed

Magnetoelectrics and multiferroics present exciting opportunities for electric-field control of magnetism. However, there are few room-temperature ferromagnetic-ferroelectrics. Among the various types of multiferroics the bismuth ferrite system has received much attention primarily because both the ferroelectric and the antiferromagnetic orders are quite robust at room temperature. Here we demonstrate the emergence of an enhanced spontaneous magnetization in a strain-driven rhombohedral and super-tetragonal mixed phase of BiFeO?. Using X-ray magnetic circular dichroism-based photoemission electron microscopy coupled with macroscopic magnetic measurements, we find that the spontaneous magnetization of the rhombohedral phase is significantly enhanced above the canted antiferromagnetic moment in the bulk phase, as a consequence of a piezomagnetic coupling to the adjacent tetragonal-like phase and the epitaxial constraint. Reversible electric-field control and manipulation of this magnetic moment at room temperature is also shown. PMID:21407191

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

2011-01-01

115

Spontaneous and stimulated emission dynamics of PbS quantum dots in a glass matrix  

NASA Astrophysics Data System (ADS)

Optical properties and relaxation mechanisms of PbS quantum dots in glass matrix (PbS:Glass) have been systematically investigated by transmission and (steady-state and transient) photoluminescence spectroscopy. Key parameters are determined by combining the data with semiempirical expressions, based on which the recombination mechanisms including spontaneous and stimulated emissions have been discussed as a function of temperature by referring to a multilevel model including intrinsic (or band-to-band transition), bright, dark, and ground states. The results disclose that (i) the existence of a dark exciton state is the main reason for thermal quenching of the emission even at low temperatures due to the strong multiacoustic phonon coupling, (ii) the ‘‘intrinsic’’ spontaneous emission related to the intrinsic state is observed with an approximately nanosecond lifetime, in contrast to the ‘‘regular’’ spontaneous emission from the bright exciton state with an approximately microsecond lifetime, and (iii) stimulated emission, which has a lifetime of 20-40 ps and shows power-dependence of excitation density (or temperature), only appears from the intrinsic state but not the (bright) exciton state when enough accumulation of photogenerated carriers is reached. Furthermore, we find that the thermal conductivity will become crucial for future PbS:Glass related optoelectronic device applications.

Yue, Fangyu; Tomm, Jens W.; Kruschke, Detlef

2013-05-01

116

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

SciTech Connect

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.

Jun, Y.C.

2010-03-02

117

Emission control system  

SciTech Connect

A gaseous fueled Otto cycle internal combustion engine is described, comprising: (1) at least one combustion chamber formed by a piston and a cylinder having intake and outlet valves; (2) intake manifold means for delivering a charge of fuel-air mixture through the intake valve to the combustion chamber; (3) mixing means connected to the intake manifold means and disposed upstream with respect to the intake valve for controlling the ratio of the fuel-air mixture; (4) spark ignition means for igniting the charge in the combustion chamber; (5) an inlet communicating with the intake manifold means and adjacent the upstream side of the intake valve, the air inlet being disposed to create when the intake valve is opened a gradient of fuel concentration within the combustion chamber consisting essentially of a layer of air adjacent the piston with the remaining portion of the combustion chamber towards the spark ignition means containing a gradually richer fuel concentration and (6) air control means adapted to permit the adjustment of the amount of air delivered through the air inlet.

Novy, V.A.

1989-05-02

118

300 ps switching of spontaneous emission by quantum confined field effect in a light emitting triode  

NASA Astrophysics Data System (ADS)

High-speed switching (as fast as 300 ps) of spontaneous emission was achieved in a quantum-confined field-effect light-emitting triode. As a result of the combination of the field control of radiative lifetime with modulation of carrier-generation rate, the light intensity modulation does not rely on changes in carrier population at all, but on the field control of the radiative lifetime in the quantum well structure of the device. The allowable deviation of the modulation depth of the injection current from the optimum condition was studied experimentally. Without the help of the slit used in the work, the present modulation scheme would be possible in a device where an inner current blocking layer restricts the collector current flow within the quantum well existing beneath the emitter mesa. It is pointed out that the high-speed capability, together with the extremely low current density of about 10 A/sq cm for the device operation and the high quantum yield eta(ex) = 1 percent or greater in the device may open up entirely new opportunities in interchip optical communication.

Ohnishi, T.; Mukaiyama, K.; Yamanishi, M.; Ochi, N.; Ono, Y.

1990-08-01

119

Electrically Controllable Spontaneous Magnetism in Nanoscale Mixed Phase Multiferroics  

SciTech Connect

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.

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

120

Spontaneous emission lifetime distribution of infinite line antennas in two-dimensional photonic crystals with finite size  

NASA Astrophysics Data System (ADS)

The authors calculate the lifetime distribution functions of spontaneous emission from infinite line antennas embedded in two-dimensional disordered photonic crystals with finite size. The calculations indicate the coexistence of both accelerated and inhibited decay processes in disordered photonic crystals with finite size. The decay behavior of the spontaneous emission from infinite line antennas changes significantly by varying factors such as the line antennas' positions in the disordered photonic crystal, the shape of the crystal, the filling fraction, and the dielectric constant. Moreover, the authors analyze the effect of the degree of disorder on spontaneous emission.

Xu, Xingsheng; Wang, Yiquan

2007-07-01

121

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

SciTech Connect

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.

Barnes, M.D.; Whitten, W.B.; Ramsey, J.M. (Oak Ridge National Lab., TN (United States)); Arnold, S. (Polytechnic Inst., of New York, Brooklyn, NY Microparticle Photophysics Lab. (United States))

1992-01-01

122

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

SciTech Connect

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.

Barnes, M.D.; Whitten, W.B.; Ramsey, J.M. [Oak Ridge National Lab., TN (United States); Arnold, S. [Polytechnic Inst., of New York, Brooklyn, NY Microparticle Photophysics Lab. (United States)

1992-11-01

123

Observation of Self-Amplified Spontaneous Emission and Exponential Growth at 530 nm  

Microsoft Academic Search

Experimental evidence for self-amplified spontaneous emission (SASE) at 530 nm is reported. The measurements were made at the low-energy undulator test line facility at the Advanced Photon Source, Argonne National Laboratory. The experimental setup and details of the experimental results are presented, as well as preliminary analysis. This experiment extends to shorter wavelengths the operational knowledge of a linac-based SASE

S. V. Milton; E. Gluskin; S. G. Biedron; R. J. Dejus; P. K. den Hartog; J. N. Galayda; K.-J. Kim; J. W. Lewellen; E. R. Moog; V. Sajaev; N. S. Sereno; G. Travish; N. A. Vinokurov; N. D. Arnold; C. Benson; W. Berg; J. A. Biggs; M. Borland; J. A. Carwardine; Y.-C. Chae; G. Decker; B. N. Deriy; M. J. Erdmann; H. Friedsam; C. Gold; A. E. Grelick; M. W. Hahne; K. C. Harkay; Z. Huang; E. S. Lessner; R. M. Lill; A. H. Lumpkin; O. A. Makarov; G. M. Markovich; D. Meyer; A. Nassiri; J. R. Noonan; S. J. Pasky; G. Pile; T. L. Smith; R. Soliday; B. J. Tieman; E. M. Trakhtenberg; G. F. Trento; I. B. Vasserman; D. R. Walters; X. J. Wang; G. Wiemerslage; S. Xu; B.-X. Yang; APS-USR

2000-01-01

124

Emission of Long-Range Alpha Particles in the Spontaneous Fission of Cf252  

Microsoft Academic Search

An experimental investigation of alpha-particle emission in the spontaneous fission of Cf252 is described. The measured angular distribution and energy distribution of the alpha particles are presented, as well as the mass-ratio distribution of the fission fragments and the single-fragment energy distribution in fission accompanied by long-range alpha particles (LRA fission). Also shown is the angular distribution of the alpha

Z. Fraenkel

1967-01-01

125

Amplified spontaneous emission from GaSb quantum dots in Si grown by MBE  

Microsoft Academic Search

Light amplifying characteristics of GaSb quantum dots embedded in Si grown on SOI were studied. Amplified spontaneous emission was observed at 6.6K under pulsed visible laser excitation. Pump power dependence of on–off gain measured in a pump-and-probe configuration showed a threshold behavior, which indicates the relevance of a three level system. At 30K, however, gain was diminished while absorption dominated,

N. Yasuhara; M. Jo; Y. Sugawara; K. Kawamoto; S. Fukatsu

2007-01-01

126

Spontaneous emission high-gain harmonic generation free-electron laser  

Microsoft Academic Search

A scheme, spontaneous emission high-gain harmonic generation (SEHG) free-electron laser (FEL), is proposed and analyzed for generating the X-ray FEL. The SEHG scheme works in a similar mechanism as high-gain harmonic generation (HGHG), but without the need for a seed laser. The scheme requires two undulators. The 1st undulator must be sufficiently long so that the energies of electrons are

Qingzi Xing; Xinlu Xu; Chao Feng; Chuanxiang Tang

2011-01-01

127

Localization of the relative position of two atoms induced by spontaneous emission  

SciTech Connect

We reexamine the back-action of emitted photons on the wave packet evolution about the relative position of two cold atoms. We show that photon recoil resulting from the spontaneous emission can induce the localization of the relative position of the two atoms through the entanglement between the spatial motion of individual atoms and their emitted photons. The obtained result provides a more realistic model for the analysis of the environment-induced localization of a macroscopic object.

Zheng, L. [Center of Theoretical Physics, Jilin University, Changchun, 130023 (China) and Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100080 (China); Li, C.; Li, Y.; Sun, C.P. [Institute of Theoretical Physics, The Chinese Academy of Science, Beijing, 100080 (China)

2005-06-15

128

Synthesis and photophysical properties of new oligophenylene vinylenes showing amplified spontaneous emission  

NASA Astrophysics Data System (ADS)

Three new phenylene vinylene oligomers containing either a bis(oligoether)phenyl ring or a benzothiadiazole central unit and either carbazole or triphenylamine end capping groups were synthesized and characterized. The photophysical characterization in solution reveals a significant variation in properties depending on the combined moieties. Amplified spontaneous emission in neat drop cast films of two of these compounds was studied. One of them was also characterized in terms of its two-photon photoluminescence.

Mendonça, A. L.; Charas, A.; Di Paolo, R. E.; Scotognella, F.; Lanzani, G.; Morgado, J.

2013-10-01

129

Scalarized photon analysis of spontaneous emission in the uniform magnetic field free-electron laser  

NASA Astrophysics Data System (ADS)

The recently developed concept of scalarized photons (formally photons of any polarization) is used to analyze the spontaneous emission in the uniform magnetic field free-electron laser in the microwave spectral region. With the electron beam energy of up to 10 MeV and the uniform magnetic field of up to 4 Tesla, the radiation (occurring with the fundamental and higher harmonic frequencies) can easily cover a 10- to 10,000 GHz spectral region.

Soln, Josip

1990-04-01

130

Spontaneous emission of a photon: Wave-packet structures and atom-photon entanglement  

Microsoft Academic Search

Spontaneous emission of a photon by an atom is described theoretically in three dimensions with the initial wave function of a finite-mass atom taken in the form of a finite-size wave packet. Recoil and wave-packet spreading are taken into account. The total atom-photon wave function is found in the momentum and coordinate representations as the solution of an initial-value problem.

M. V. Fedorov; M. A. Efremov; A. E. Kazakov; K. W. Chan; J. H. Eberly; C. K. Law

2005-01-01

131

Amplification of spontaneous emission in erbium-doped single-mode fibers  

Microsoft Academic Search

Amplification of spontaneous emission (ASE) in erbium-doped single-mode fiber amplifiers operating at ?=1.53 ?m is studied theoretically and experimentally. The ASE noise spectra obtained from the theory are found to be in excellent quantitative agreement with the experimental data. The observed changes in ASE spectral shapes under different population inversion conditions are also explained. The model may be used to

Emmanuel Desurvire; JAY R. SIMPSON

1989-01-01

132

A unified analysis of spontaneous and super-radiant emissions in free-electron lasers  

Microsoft Academic Search

A generalized formulation of spontaneous emission and super-radiance effects in a free-electron laser is presented. We consider a stream of electrons of arbitrary temporal duration propagating through the undulator. The sum of the undulator synchrotron radiation emitted by individual wiggling electrons entering the wiggler at random, results in shot-noise in the radiation field.Using the waveguide excitation equations formulated in the

Y. Pinhasi; A. Gover

1997-01-01

133

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

NASA Astrophysics Data System (ADS)

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.

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

2009-08-01

134

Periodontal disease and spontaneous preterm birth: a case control study  

PubMed Central

Background Several studies have suggested an association between periodontal disease and prematurity but this finding has not been consistently observed. Methods Case control study. Cases (n = 50) were women who had delivered after spontaneous preterm labor at <35 weeks gestation. Two groups of controls (n = 101) were recruited: women who were undelivered but at a preterm gestation and women who delivered at term. A standard, clinical, periodontal examination was performed and gingival crevicular fluid was obtained from standardized locations and tested for neutrophil elastase along with the bacterial enzymes gingipain and dipeptidylpeptidase. Data were analyzed with Fisher's exact tests, ANOVA and multivariate logistic regression. Results There was no difference in the proportion of sites with significant attachment loss (?3 mm): Cases-3.2%, Controls-2.2% p = 0.21. The gingival crevicular fluid concentrations of elastase and gingipain were elevated in cases vs. controls 238.8 uU/ul vs. 159.6 uU/ul p = .007 and 2.70 uU/ul vs. 1.56 uU/ul p = .001. On multivariate analysis, the mean log concentration of elastase, but not of gingipain, remained a significant predictor of preterm labor p = .0.015. Conclusion We found no evidence that clinical periodontal disease is associated with spontaneous preterm birth. Elevated gingival crevicular fluid levels of elastase were associated with preterm birth but further research is needed before this can be assumed to be a causal relationship.

Wood, Stephen; Frydman, Albert; Cox, Stephen; Brant, Rollin; Needoba, Sheilia; Eley, Barry; Sauve, Reg

2006-01-01

135

Review of the Pollution Control and Ecological Restoration of Coal Waste Piles with Spontaneous Combustion  

Microsoft Academic Search

Spontaneous combustion of coal waste piles lead to a lot of pollutions. Pollution control and ecological restoration of coal waste piles with spontaneous combustion has become central issue of national research. In this paper, the mechanism of spontaneous combustion of coal waste piles is discussed, types and causes of pollution are analyzed, and technologies of pollution control and ecological restoration

Lei Zhang; Bi Kai Gong; Xue Ran Liu; Meng Peng; Guo Qiang Zhang; Ya Li Shi

2011-01-01

136

Amplified spontaneous emission in an organic semiconductor multilayer waveguide structure including a highly conductive transparent electrode  

NASA Astrophysics Data System (ADS)

We demonstrate that the amplified spontaneous emission (ASE) threshold in multilayer waveguide structures suitable for the use in future organic injection lasers can be drastically reduced by inserting a crosslinked hole transport layer (HTL) between a highly conductive indium tin oxide (ITO) electrode and the polymer emission layer. While no ASE is observed when the active layer material is directly spincoated onto the ITO electrode, it can be completely restored upon insertion of a 300-nm-thick HTL. This observation is attributed to reduced attenuation of the waveguided mode enabling the ASE process and is theoretically confirmed by calculations of the mode intensity fraction propagating in the absorptive ITO electrode.

Reufer, M.; Feldmann, J.; Rudati, P.; Ruhl, A.; Müller, D.; Meerholz, K.; Karnutsch, C.; Gerken, M.; Lemmer, U.

2005-05-01

137

Study of the gamma emission probability accompanying the spontaneous fission of 252Cf.  

NASA Astrophysics Data System (ADS)

A study of the gamma emission accompanying the spontaneous fission process of 252Cf has been performed. The photon emission probability between 3 and 70 MeV and its angular dependence with respect to the fission direction were measured. These measurements were performed as a function of the mass asymmetry of the fission fragments. A large anisotropy in the energy region between 8 and 12 MeV has been found, confirming the results of a previous performed experiment [1]. This phenomena up till now remains unexplained.

van der Ploeg, H.; Laurens, C. R.; Bacelar, J. C. S.; Buda, A.; Gaardhøje, J. J.; van't Hof, G.; Kalantar-Nayestanaki, N.; van der Woude, A.; Zelazny, Z.

1994-03-01

138

Amplified spontaneous emission from single CdS nanoribbon with low symmetric cross sections.  

PubMed

CdS nanoribbons with various cross sections offer the opportunity to deeply understand the interaction between optical cavity and spontaneous emission. Herein, long tapered nanoribbons with the cross sections gradually changing were synthesized by a simple physical vapour deposition method. Morphology dependent micro-region photoluminescence (PL) spectroscopy is employed to show Purcell effect along different low symmetry cross sections. Spikes on the PL spectra reveal that local density of optical modes increases when the mode match happens between optical cavity and spontaneous emission. Bound exciton complex related amplified spontaneous emission is observed in a single CdS nanoribbon with well-defined elliptical cross sections and optimized width/thickness ratio ?1.45. Polarized Raman and TEM confirmed that the nanoribbon with the elliptical cross section adopts the [0002] growth direction with good quality. The results suggest that the cross section resonant cavity would be of importance for both fundamental and practical application of cavity quantum electrodynamics in CdS nanoribbon. PMID:22868895

Xu, Xin Long; Wang, Jian Xiong; Jing, Guang Yin; Shen, Ze Xiang; Zou, Bing Suo; Fan, Hai Ming; Olivo, Malini

2012-08-07

139

Amplified spontaneous emission from single CdS nanoribbon with low symmetric cross sections  

NASA Astrophysics Data System (ADS)

CdS nanoribbons with various cross sections offer the opportunity to deeply understand the interaction between optical cavity and spontaneous emission. Herein, long tapered nanoribbons with the cross sections gradually changing were synthesized by a simple physical vapour deposition method. Morphology dependent micro-region photoluminescence (PL) spectroscopy is employed to show Purcell effect along different low symmetry cross sections. Spikes on the PL spectra reveal that local density of optical modes increases when the mode match happens between optical cavity and spontaneous emission. Bound exciton complex related amplified spontaneous emission is observed in a single CdS nanoribbon with well-defined elliptical cross sections and optimized width/thickness ratio ~1.45. Polarized Raman and TEM confirmed that the nanoribbon with the elliptical cross section adopts the [0002] growth direction with good quality. The results suggest that the cross section resonant cavity would be of importance for both fundamental and practical application of cavity quantum electrodynamics in CdS nanoribbon.

Xu, Xin Long; Wang, Jian Xiong; Jing, Guang Yin; Shen, Ze Xiang; Zou, Bing Suo; Fan, Hai Ming; Olivo, Malini

2012-08-01

140

Numerical study of amplified spontaneous emission and lasing in random media  

SciTech Connect

We simulate the transition from amplified spontaneous emission (ASE) to lasing in random systems with varying degrees of mode overlap. This is accomplished by solving the stochastic Maxwell-Bloch equations with the finite-difference time-domain method. Below lasing threshold, the continuous emission spectra are narrowed by frequency-dependent amplification. Our simulations reproduce the stochastic emission spikes in the spectra. Well-defined peaks, corresponding to the system resonances, emerge at higher pumping and are narrowed by stimulated emission before lasing takes place. Noise tends to distribute pump energy over many modes, resulting in multimode operation. Well above the lasing threshold, the effects of noise lessen and results become similar to those without noise. By comparing systems of different scattering strength, we find that weaker scattering extends the transition region from ASE to lasing, where the effects of noise are most significant.

Andreasen, Jonathan [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Cao Hui [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States)

2010-12-15

141

Quantum interference due to energy shifts and its effect on spontaneous emission  

SciTech Connect

We study the quantum interference in spontaneous emission with the inclusion of counterrotating terms and energy shifts. The energy shifts come from the emission and then reabsorption of virtual photons as well as the real photon emission. We show that the quantum interference resulting from the energy shifts has significant influence on the effective decay rates of the two levels, even when the transition dipole elements are the same and the energy separation of the two levels is small. We also show that the energy shift has substantial influence on the spectrum emitted by the atom. The result is valid in the long time limit. The effect of the energy shift can be observed at the time scale of 1 over the atomic decay rate. We suggest an experiment to test the effect of quantum interference because of energy shifts on the emission spectrum.

Li Zhenghong; Zhu Shiyao [Beijing Computational Science Research Center, Beijing 100084 (China); Department of Physics, Hong Kong Baptist University (Hong Kong); Wang Dawei; Zheng Hang [Beijing Computational Science Research Center, Beijing 100084 (China); Zubairy, M. Suhail [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843-4242 (United States)

2010-11-15

142

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

SciTech Connect

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.

Jun, Y.C.

2010-02-24

143

Spontaneous emission near the band edge of a three-dimensional photonic crystal: a fractional calculus approach  

Microsoft Academic Search

We suggest a better mathematical method, fractional calculus, for studying the behavior of the atom-field interaction in photonic crystals. By studying the spontaneous emission of an atom in a photonic crystal with a one-band isotropic model, we found that the long-time inducing memory of the spontaneous emission is a fractional phenomenon. This behavior could be well described by fractional calculus.

Szu-Cheng Cheng; Jing-Nuo Wu; Ming-Rung Tsai; Wen-Feng Hsieh

2009-01-01

144

Performance of a quantum teleportation protocol based on spontaneous emission from a pair of atoms  

NASA Astrophysics Data System (ADS)

Recently a quantum teleportation protocol has been proposed by Chen, et al. in New Journal of Physics 7, 172 (2005) which is based on the collective spontaneous emission of a photon from a pair of atoms. If one can successfully distinguish between the superradiant and subradiant emission channels then one can teleport the state of the second atom onto a cavity field mode with which the first atom has previously interacted. One can employ temporal resolution, spatial resolution, or both in combination, of the emitted photon in order to distinguish superradiant from subradiant emission on the basis of a single detected photon. Using a quantum trajectory unraveling of the superradiance master equation developed previously [Phys. Rev. A 68, 023809 (2003)] we calculate the overall success probability and the fidelity of the teleportation protocol under all three detection strategies. We investigate the performance of the protocol, optimizing with respect to the spacing of the two atoms.

Clemens, James

2006-05-01

145

Optimization of a quantum teleportation protocol based on collective spontaneous emission  

NASA Astrophysics Data System (ADS)

Recently a quantum teleportation protocol has been proposed by Chen, et al. in New Journal of Physics 7, 172 (2005) which is based on the collective spontaneous emission of a photon from a pair of atoms. If one can successfully distinguish between the superradiant and subradiant emission channels then one can teleport the state of the second atom onto a cavity field mode with which the first atom has previously interacted. One can employ temporal resolution, spatial resolution, or both in combination, of the emitted photon in order to distinguish superradiant from subradiant emission on the basis of a single detected photon. The overall success probability of the teleportation protocol is calculated under all three detection strategies and is optimized with respect to the spacing of the two atoms.

Clemens, James

2006-03-01

146

Evidence for the stochastic aspect of prompt ? emission in spontaneous fission  

NASA Astrophysics Data System (ADS)

The prompt ?-ray energy and multiplicity distributions in the spontaneous fission of 252Cf have been measured using a highly segmented 4? ?-ray calorimeter. Corrections were made for both distributions according to the detector response, which is simulated numerically using a model validated with the ?-ray calibration sources. A comparison of the total ?-ray energy distribution was made between the measurement and a simulation performed by random sampling of the corrected ?-ray energy and multiplicity distributions and then transporting those ? rays through the response of the detector array. The agreement between the measurement and simulation for the mean energy and width is markedly improved at higher multiplicities compared to the lower ones, illustrating the diminishing correlation between the ?-ray and multiplicity energy and the stochastic aspect of the prompt ? emission in spontaneous fission at higher multiplicities.

Chyzh, A.; Wu, C. Y.; Kwan, E.; Henderson, R. A.; Gostic, J. M.; Bredeweg, T. A.; Haight, R. C.; Hayes-Sterbenz, A. C.; Jandel, M.; O'Donnell, J. M.; Ullmann, J. L.

2012-02-01

147

Observation of Free-Electron-Laser-Induced Collective Spontaneous Emission (Superfluorescence)  

NASA Astrophysics Data System (ADS)

We have observed and characterized 501.6 nm collective spontaneous emission (superfluorescence) following 1s2?1s3p excitation of helium atoms by 53.7 nm free-electron laser radiation. Emitted pulse energies of up to 100 nJ are observed, corresponding to a photon number conversion efficiency of up to 10%. We observe the peak intensity to scale as ?2 and the emitted pulse width and delay to scale as ?-1, where ? is the atom number density. Emitted pulses as short as 1 ps are observed, which corresponds to a rate around 75 000 times faster than the spontaneous 1s3p?1s2s decay rate. To our knowledge, this is the first observation of superfluorescence following pumping in the extreme ultraviolet wavelength region, and extension of the technique to the generation of extreme ultraviolet and x-ray superfluorescence pulses should be straightforward by using suitable atomic systems and pump wavelengths.

Nagasono, Mitsuru; Harries, James R.; Iwayama, Hiroshi; Togashi, Tadashi; Tono, Kensuke; Yabashi, Makina; Senba, Yasunori; Ohashi, Haruhiko; Ishikawa, Tetsuya; Shigemasa, Eiji

2011-11-01

148

Microscopic Theory of Optical Nonlinearities and Spontaneous Emission Lifetime in Group-III Nitride Quantum Wells  

SciTech Connect

Microscopic calculations of the absorption/gain and luminescence spectra are presented for wide bandgap Ga{sub 1{minus}x}In{sub x}N/GaN quantum well systems. Whereas structures with narrow well widths exhibit the usual excitation dependent bleaching of the exciton resonance without shifting spectral position, a significant blue shift of the exciton peak is obtained for wider quantum wells. This blue shift, which is also present in the excitation dependent luminescence spectra, is attributed to the interplay between the screening of a strain induced piezoelectric field and the density dependence of many-body Coulomb effects. The calculations also show an over two orders of magnitude increase in the spontaneous electron-hole-pair lifetime with well width: due to the reduction of the electron-hole wavefunction overlap in the wider wells. The resulting decrease in spontaneous emission loss is predicted to lead to improved threshold properties in wide quantum well lasers.

Chow, W.; Kira, M.; Koch, S.W.

1999-03-16

149

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

SciTech Connect

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.

Maydanyuk, S. P.; Olkhovsky, V. S.; Mandaglio, G.; Manganaro, M.; Fazio, G.; Giardina, G. [Institute for Nuclear Research, National Academy of Science of Ukraine, Kiev 03680 (Ukraine); Dipartimento di Fisica dell'Universita di Messina, I-98166 Messina (Italy) and Istituto Nazionale di Fisica Nucleare, Sezione di Catania, I-95123 Catania (Italy)

2010-07-15

150

Bremsstrahlung emission of high energy accompanying spontaneous fission of Cf252  

NASA Astrophysics Data System (ADS)

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 Cf252 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 Cf252 is presented.

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

2010-07-01

151

Output power stabilized dual-order Raman fiber laser by generated amplified spontaneous emission  

NASA Astrophysics Data System (ADS)

A dual-order Raman fiber laser (RFL) is numerically presented with suppressed low-frequency relative-intensity-noise transfer from pump sources to both the first- and second-order Stokes output. It is accomplished by generating the amplified spontaneous emission near second-order Stokes shift from the launched pump. Their powers can be tuned in a large dynamic range. Besides these, the low-power second-order Stokes output is also stabilized in the RFL setup. These special behaviors fit the proposed RFL for use as dual-order pump sources in Raman fiber amplifiers.

Zhou, Yingwu; Cheng, Min; Luo, Zhizhao

2008-11-01

152

Spontaneous emission and collection efficiency enhancement of single emitters in diamond via plasmonic cavities and gratings  

NASA Astrophysics Data System (ADS)

We demonstrate an approach, based on plasmonic apertures and gratings, to enhance the radiative decay rate of single nitrogen-vacancy (NV) centers in diamond while simultaneously improving their collection efficiency. Our structures are based on metallic resonators formed by surrounding sub-wavelength diamond nanoposts with a silver film, which can enhance the spontaneous emission rate of an embedded NV center. However, the collection efficiency of emitted photons remains low due to losses to surface plasmons and reflections at the diamond-air interface. In this work, we mitigate photon losses into these channels by incorporating grating structures into the plasmonic cavity system.

Choy, Jennifer T.; Bulu, Irfan; Hausmann, Birgit J. M.; Janitz, Erika; Huang, I.-Chun; Lon?ar, Marko

2013-10-01

153

Measurement of the amplified spontaneous emission loss in an iodine photodissociation laser amplifier  

SciTech Connect

The directional amplified spontaneous emission (ASE) along the laser tube of an iodine photodissociation laser (IPL) amplifier is measured and the experimental results are compared with the one-dimensional ASE theory. Also, we have measured the loss of the stored energy in the IPL amplifier due to the omnidirectional ASE. The loss is found to be 13.5% for the present amplifier when the laser medium i-C/sub 3/F/sub 7/I is 72 Torr and no argon buffer gas is added. But by adding the argon buffer gas to 210 Torr, it is reduced to 4.2%.

Hahn, J.W.; Lee, S.S.

1985-11-15

154

Intuitive and rigorous derivation of spontaneous emission and Landau damping of Langmuir waves through classical mechanics  

SciTech Connect

Classical mechanics provides the intuitive and unified description of spontaneous emission, Landau growth and damping of Langmuir waves, the cold beam{endash}plasma instability, and van Kampen modes. This is done by studying the interaction between {ital M} weak modes of a plasma without resonant particles and {ital N} quasiresonant particles, which leads to an exactly solvable high-dimensional Floquet problem. Growth corresponds to an eigenmode of the system, whereas damping requires statistical averaging. Both imply synchronization of near-resonant particles with waves, and the corresponding force on individual particles is computed explicitly. {copyright} {ital 1996 American Institute of Physics.}

Escande, D.F.; Zekri, S.; Elskens, Y. [Equipe Turbulence Plasma de l`URA 773 CNRS---Universite de Provence, Institut Mediterraneen de Technologie, F-13451 Marseille cedex 20 (France)

1996-10-01

155

Observation of {sup 10}Be Emission in the Cold Ternary Spontaneous Fission of {sup 252}Cf  

SciTech Connect

The emission of {sup 10}Be in ternary cold neutronless spontaneous fission of {sup 252}Cf is observed with the Gammasphere consisting of 72 detectors. The {gamma} ray corresponding to the decay of the first 2{sup +} state in {sup 10}Be is observed in coincidence with the {gamma} rays of the fission partners of {sup 96}Sr and {sup 146}Ba . The yield to the first excited state of {sup 10}Be in the {sup 96}Sr- {sup 146}Ba split is the order of 4.0{times}10{sup {minus}4} per 100 fission events. {copyright} {ital 1998} {ital The American Physical Society}

Ramayya, A.V.; Hwang, J.K.; Hamilton, J.H.; Sandulescu, A.; Florescu, A.; Ter-Akopian, G.M.; Daniel, A.V.; Popeko, G.S.; Greiner, W. [Physics Department, Vanderbilt University, Nashville, Tennessee 37235 (United States); Sandulescu, A.; Florescu, A. [Institute for Atomic Physics, Bucharest, P.O. Box MG-6 (Romania); Sandulescu, A.; Greiner, W. [Institute fuer Theoretische Physik der J. W. Goethe Universitaet, D-60054, Frankfurt am Main (Germany); Ter-Akopian, G.M.; Daniel, A.V.; Oganessian, Y.T.; Popeko, G.S. [Joint Institute for Nuclear Research, Dubna 141980 (Russia); Florescu, A.; Ter-Akopian, G.M.; Daniel, A.V.; Greiner, W. [Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee 37830 (United States); Cole, J.D. [Idaho National Engineering Laboratory, Idaho Falls, Idaho 83415-2114 (United States)

1998-08-01

156

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

157

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

Microsoft Academic Search

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

Xiulin Wang; Wencai Huang

2006-01-01

158

Amplified spontaneous emission and pulse train amplification in a KrF amplifier  

SciTech Connect

We present modeling status of pulse-train amplification experiments conducted at Sandia National Laboratory in Albuquerque (SNLA) with an e-beam pumped KrF laser amplifier. The laser geometry is such that the dominant amplified spontaneous emission (ASE) growth is along the propagation axis. Our numerical studies include the propagation of on axis co- and counter-propagating fields for both the pulse train and ASE simultaneously. The time-dependent gain, absorption, formation and quenching rates are obtained from a state-of-the-art kinetics code developed at Los Alamos National Laboratory (LANL). 12 refs., 12 figs.

Ackerhalt, J.R.; Hanson, D.E.; Adams, R.G.; Raymond, T.D.; Reiser, C.; Rice, J.K.; Michie, R.B.

1988-01-01

159

Long-lived quantum coherence of two-level spontaneous emission models within structured environments.  

PubMed

We investigate the long-lived quantum coherence of two-level spontaneous emission models within structured environments. The population of the system under the asymptotic non-Markovian dynamics is linked to the spectral density of the reservoir through a general functional relation between them. We figure out explicitly the preservation of quantum coherence, via notions of entanglement and quantum discord, in connection with the spectral parameters of Ohmic class reservoirs, and then show how to achieve them optimally. We expect these results to contribute to reservoir engineering with the aim of enhancing stationary quantum coherence in noisy environments. PMID:24104837

Zhang, Ping; You, Bo; Cen, Li-Xiang

2013-09-15

160

Observation of Self-Amplified Spontaneous Emission and Exponential Growth at 530 nm  

NASA Astrophysics Data System (ADS)

Experimental evidence for self-amplified spontaneous emission (SASE) at 530 nm is reported. The measurements were made at the low-energy undulator test line facility at the Advanced Photon Source, Argonne National Laboratory. The experimental setup and details of the experimental results are presented, as well as preliminary analysis. This experiment extends to shorter wavelengths the operational knowledge of a linac-based SASE free-electron laser and explicitly shows the predicted exponential growth in intensity of the optical pulse as a function of length along the undulator.

Milton, S. V.; Gluskin, E.; Biedron, S. G.; Dejus, R. J.; den Hartog, P. K.; Galayda, J. N.; Kim, K.-J.; Lewellen, J. W.; Moog, E. R.; Sajaev, V.; Sereno, N. S.; Travish, G.; Vinokurov, N. A.; Arnold, N. D.; Benson, C.; Berg, W.; Biggs, J. A.; Borland, M.; Carwardine, J. A.; Chae, Y.-C.; Decker, G.; Deriy, B. N.; Erdmann, M. J.; Friedsam, H.; Gold, C.; Grelick, A. E.; Hahne, M. W.; Harkay, K. C.; Huang, Z.; Lessner, E. S.; Lill, R. M.; Lumpkin, A. H.; Makarov, O. A.; Markovich, G. M.; Meyer, D.; Nassiri, A.; Noonan, J. R.; Pasky, S. J.; Pile, G.; Smith, T. L.; Soliday, R.; Tieman, B. J.; Trakhtenberg, E. M.; Trento, G. F.; Vasserman, I. B.; Walters, D. R.; Wang, X. J.; Wiemerslage, G.; Xu, S.; Yang, B.-X.

2000-07-01

161

Tuning Spontaneous Emission versus Forster Energy Transfer in Biological Systems by Manipulating the Density of Photonic States  

Microsoft Academic Search

We theoretically discuss how to tune the competition between Forster transfer and spontaneous emission in a continuous and nondestructive fashion. The proposed approach is especially suitable for delicate biological systems like light harvesting complexes and fluorescent protein oligomers. We demonstrate that the manipulation of the density of photonic states at the emission frequency of the energy donor results in a

Christian Blum; Willem L. Vos; Vinod Subramaniam

2007-01-01

162

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...

163

Probing the Spontaneous Emission Dynamics in Si-Nanocrystals-Based Microdisk Resonators  

NASA Astrophysics Data System (ADS)

As a possible cavity quantum electrodynamical system, unlike III-V quantum dots, Si-NCs are not considered ideal emitters for emission rate enhancement observations (Purcell effect). Here, we report on direct measurements of spontaneous emission rate enhancement of Si-NCs embedded in a whispering-gallery mode resonator at room temperature. Using time-resolved microphotoluminescence experiments, we demonstrate important lifetime reductions (˜70%) for Si-NCs coupled to cavity modes with respect to uncoupled ones. Comparing experiments with the theoretical Purcell enhancement in a bad emitter regime, we estimate effective linewidths of ˜10meV through which Si-NC emitters are coupled to cavity photons. Finally, our study provides an alternative method for the estimation of subnatural linewidths of quantum dots at room temperature.

Pitanti, A.; Ghulinyan, M.; Navarro-Urrios, D.; Pucker, G.; Pavesi, L.

2010-03-01

164

Modification of visible spontaneous emission with silicon nitride photonic crystal nanocavities.  

PubMed

Photonic crystal (PC) nanocavities based on silicon nitride membranes are studied as tools for the manipulation of spontaneous emission in the wavelength range between 550 nm and 800 nm. We observe a strong modification of the fluorescence spectrum of dye molecules spin-cast on top of the PC, indicating an efficient coupling of the dye emission to the cavity modes. The cavity design is optimized with respect to the quality factor and values of nearly 1500 are achieved experimentally. Taking into account the small mode volume, which leads to a strong Purcell enhancement, these nanocavities enable the realization of efficient single photon sources in the visible region of the spectrum. Furthermore, their fabrication is fully compatible with existing CMOS technology, making an integration into more complex optoelectronic devices feasible. PMID:19551016

Barth, Michael; Kouba, Josef; Stingl, Johannes; Löchel, Bernd; Benson, Oliver

2007-12-10

165

Dynamics of spontaneous emission in a single-end photonic waveguide  

NASA Astrophysics Data System (ADS)

We investigate the spontaneous emission of a two-level system, e.g., an atom or atomlike object, coupled to a single-end, i.e., a semi-infinite, one-dimensional photonic waveguide such that one end behaves as a perfect mirror while light can pass through the opposite end with no backreflection. Through a quantum microscopic model we show that such geometry can cause nonexponential and long-lived atomic decay. Under suitable conditions, a bound atom-photon stationary state appears in the atom-mirror interspace so as to trap a considerable amount of initial atomic excitation. Yet this can be released by applying an atomic frequency shift, causing a revival of photon emission. The resilience of such effects to typical detrimental factors is analyzed.

Tufarelli, Tommaso; Ciccarello, Francesco; Kim, M. S.

2013-01-01

166

Enhanced spontaneous emission of CdSe quantum dots in monolithic II-VI pillar microcavities  

NASA Astrophysics Data System (ADS)

The emission properties of CdSe/ZnSe quantum dots in ZnSe-based pillar microcavities are studied. All-epitaxial cavities made of ZnSSe and MgS/ZnCdSe superlattices with a single quantum-dot sheet embedded have been grown by molecular beam epitaxy. Pillar structures with diameters down to 500 nm have been realized by focused-ion-beam etching. A pronounced enhancement of the spontaneous emission rate of quantum dots coupling to the fundamental mode of the cavities is found as evidence for the Purcell effect. The enhancement by a factor of up to 3.8 depends systematically on the pillar diameter and thus on the Purcell factor of the individual pillars.

Lohmeyer, H.; Kruse, C.; Sebald, K.; Gutowski, J.; Hommel, D.

2006-08-01

167

Enhanced spontaneous emission of CdSe quantum dots in monolithic II-VI pillar microcavities  

SciTech Connect

The emission properties of CdSe/ZnSe quantum dots in ZnSe-based pillar microcavities are studied. All-epitaxial cavities made of ZnSSe and MgS/ZnCdSe superlattices with a single quantum-dot sheet embedded have been grown by molecular beam epitaxy. Pillar structures with diameters down to 500 nm have been realized by focused-ion-beam etching. A pronounced enhancement of the spontaneous emission rate of quantum dots coupling to the fundamental mode of the cavities is found as evidence for the Purcell effect. The enhancement by a factor of up to 3.8 depends systematically on the pillar diameter and thus on the Purcell factor of the individual pillars.

Lohmeyer, H.; Kruse, C.; Sebald, K.; Gutowski, J.; Hommel, D. [Institute of Solid State Physics, University of Bremen, Postfach 330 440, 28334 Bremen (Germany)

2006-08-28

168

Amplified spontaneous emission (ASE) models and approximations for thin-disk laser modeling  

NASA Astrophysics Data System (ADS)

It is well-known that amplified spontaneous emission (ASE) can be a major source of upper laser level loss in high gain pulsed or steady-state solid state lasers. This paper briefly reviews the theory of ASE and, using a simple rate equation model of the upper laser level, a geometric, radiative transport equation to describe the ASE intensity, and the perturbation method of multiple time scales, demonstrates that the loss rate of the upper laser level due to ASE adiabatically follows the spontaneous emission source term. This result which includes gain saturation is applicable to both quasi-three level and four level lasers and rigorously justifies formally using the steady-state expression derived heuristically by Lowenthal and Eggleston1 to model ASE loss in pulsed laser media. Then, it is shown that the frequency integral occurring in the ASE loss term can be evaluated analytically for both a broad "flat-top" and a Lorentzian stimulated emission lineshape but must be evaluated numerically or using an approximation due to Tommasini and Balmer2 for a Gaussian stimulated emission lineshape. It is shown that at high gain loss due to ASE is mitigated by ASE line narrowing. For a thin disk laser an approximate expression for the rate of ASE loss (or ASE lifetime) can be obtained by evaluating the remaining volume integral using either the method of Speiser3 or of Vretenar et al4. A new approximate expression for the ASE loss rate is obtained which, unlike Speiser's3 expression, accounts for ASE line narrowing and, unlike Vretenar et al's4 expression, correctly scales with the cylindrical volume of the disk. Application to both 1D and 3D laser modeling is briefly discussed.

Copeland, Drew A.

2013-03-01

169

Effects of low-frequency biasing on spontaneous otoacoustic emissions: Frequency modulation  

PubMed Central

It was previously reported that low-frequency biasing of cochlear structures can suppress and modulate the amplitudes of spontaneous otoacoustic emissions (SOAEs) in humans [Bian, L. and Watts, K. L. (2008). “Effects of low-frequency biasing on spontaneous otoacoustic emissions: Amplitude modulation,” J. Acoust. Soc. Am. 123, 887–898]. In addition to amplitude modulation, the bias tone produced an upward shift of the SOAE frequency and a frequency modulation. These frequency effects usually occurred prior to significant modifications of SOAE amplitudes and were dependent on the relative strength of the bias tone and a particular SOAE. The overall SOAE frequency shifts were usually less than 2%. A quasistatic modulation pattern showed that biasing in either positive or negative pressure direction increased SOAE frequency. The instantaneous SOAE frequency revealed a “W-shaped” modulation pattern within one biasing cycle. The SOAE frequency was maximal at the biasing extremes and minimized at the zero crossings of the bias tone. The temporal modulation of SOAE frequency occurred with a short delay. These static and dynamic effects indicate that modifications of the mechanical properties of the cochlear transducer could underlie the frequency shift and modulation. These biasing effects are consistent with the suppression and modulation of SOAE amplitude due to shifting of the cochlear transducer operating point.

Bian, Lin

2008-01-01

170

Collective spontaneous emission in coupled quantum dots: Physical mechanism of quantum nanoantenna  

NASA Astrophysics Data System (ADS)

We investigate the collective spontaneous emission in a system of two identical quantum dots (QDs) strongly coupled through the dipole-dipole (d-d) interaction. The QDs are modeled as two-level quantum objects, while the d-d interaction is described as the exchange of a virtual photon through the photonic reservoir. The master equation approach is used in the analysis. The main attention is focused on antenna characteristics of the two-QD system—the radiation intensity dependence on the meridian and azimuthal angles of observation. We show that the radiation pattern of such a system is nonstationary and its temporal behavior depends on the initial quantum state. In particular, for entangled initial states the radiative pattern exhibits oscillations on the frequency which corresponds to the d-d interaction energy. We also analyze spectral properties of the directional diagram. The comparison of radiation patterns is carried out for two QDs and two classical dipoles. The concept of quantum nanoantenna is proposed based on collective spontaneous emission in QD ensembles.

Mokhlespour, Salman; Haverkort, J. E. M.; Slepyan, Gregory; Maksimenko, Sergey; Hoffmann, A.

2012-12-01

171

Mesoscopic Entanglement Induced by Spontaneous Emission in Solid-State Quantum Optics  

NASA Astrophysics Data System (ADS)

Implementations of solid-state quantum optics provide us with devices where qubits are placed at fixed positions in photonic or plasmonic one-dimensional waveguides. We show that solely by controlling the position of the qubits and with the help of a coherent driving, collective spontaneous decay may be engineered to yield an entangled mesoscopic steady state. Our scheme relies on the realization of pure superradiant Dicke models by a destructive interference that cancels dipole-dipole interactions in one dimension.

González-Tudela, Alejandro; Porras, Diego

2013-02-01

172

Performance of a quantum teleportation protocol based on collective spontaneous emission  

SciTech Connect

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.

Wagner, Richard Jr.; Clemens, James P. [Department of Physics, Miami University, Oxford, Ohio 45056 (United States)

2009-03-15

173

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 ...

174

Comparison of the classical rate and the Einstein coefficient for spontaneous emission in a light-absorbing cavity  

NASA Astrophysics Data System (ADS)

The rate of spontaneous electromagnetic emission in a cavity is the normalized output radiation rate in the classical electrodynamics and the Einstein A coefficient in a quantum theory. We reveal the difference and similarity between the quantum and classical rates by calculations of the relative output power of the resonant spontaneous electric-dipole emission as a function of light absorption in a high- Q cavity. We show that the relative resonant output power is equal to the relative width of a morphology-dependent resonance in the spectral dependence of the Einstein A coefficient. The validity of the theory is demonstrated by numerical verification of an experimental result on a microsphere.

Datsyuk, Vitaly V.; Juodkazis, Saulius; Misawa, Hiroaki

2005-08-01

175

Observation of novel radioactive decay by spontaneous emission of complex nuclei  

SciTech Connect

Two years of experimental investigation on the subject of spontaneous emission of intermediate-mass fragments is described in this manuscript. A short introduction on this subject and a historical review are presented in chapter 1. In chapter 2, the author describe the experimental methods which led to the observation of /sup 14/C emission in polycarbonate etched-track detectors from the isotopes /sup 222/Ra, /sup 223/Ra, /sup 224/Ra and /sup 226/Ra at the branching ratios with respect to ..cap alpha..-decay of (3.7 +/- 0.6) x 10/sup -10/, (6.1 +/- 1.0) x 10/sup -10/, (4.3 +/- 1.2) x 10/sup -10/ and (2.9 +/- 1.0) x 10/sup -11/ respectively. Branching ratio limits for heavy-ion emission from /sup 221/Fr, /sup 221/Ra and /sup 225/Ac were determined to be at < 5.0 x 10/sup -14/, < 1.2 x 10/sup -13/ and < 4.0 x 10/sup -13/ respectively for the 90% C.L. The emission of /sup 24/Ne from /sup 232/U at a branching ratio of (2.0 +/- 0.5) x 10/sup -12/ has been discovered using polyethylene terephthalate etched-track plastics. A confirmation of /sup 24/Ne and/or /sup 25/Ne emission from /sup 233/U at a branching ratio of (5.3 +/- 2.3) x 10/sup -13/ is also reported. In chapter 3, three models of intermediate-mass decay are discussed-the analytic superasymmetric fission model, the model by Shi and Swiatecki, and a model based on a square-well + Coulomb potential.

Barwick, S.W.

1986-01-01

176

Multidimensional Monte Carlo model for two-photon laser-induced fluorescence and amplified spontaneous emission  

NASA Astrophysics Data System (ADS)

This paper describes the development of a multidimensional model based on the Monte Carlo (MC) method for the modeling of laser-induced fluorescence (LIF) and amplified spontaneous emission (ASE) signals involved in multi-photon processes. Multi-photon LIF finds applications in a broad range of topics; however, the interpretation of the LIF signal is plagued by the nonlinear effects caused by the ASE. Past work focused on developing one-dimensional (1D) models. Therefore, this work developed an MC method to solve the governing equations of ASE and LIF in multidimension. The results were validated using existing 1D data, both experimental and modeling. The results suggest that past 1D models cause noticeable error in the ASE signal even when the measurement volume has a large aspect ratio. We expect this work to facilitate the ongoing research of multi-photon LIF, and to stimulate new experiments that can provide data to validate the model in 2D.

Zhao, Yan; Li, Xuesong; Ma, Lin

2012-08-01

177

Low threshold amplified spontaneous emission from dye-doped DNA biopolymer  

NASA Astrophysics Data System (ADS)

In this study, we investigate the amplified spontaneous emission (ASE) properties and conduct a comparative study for two kinds of dye-doped deoxyribonucleic acid (DNA) biopolymers. The system consists of optical films made of DNA modified by two types of surfactants and doped with a common laser dye rhodamine 6G (Rh6G). The ASE properties of the optical films were characterized by a pulsed Nd:YAG laser. The results show that low threshold of DNA biopolymer can be achieved by the employment of suitable surfactant in the system, resulting from an efficient energy transfer process. Coupled with the fluorescence enhancement exhibited in DNA, this effect can further advance biopolymers toward highly efficient media for lasing applications and organic solid-state lasers.

Hung, Yu-Chueh; Su, Che-Hsuan; Huang, Hsien-Wen

2012-06-01

178

Ultra-broadband amplified spontaneous emission source by using heterogeneous optical amplifier  

NASA Astrophysics Data System (ADS)

In this work, we propose and experimentally investigate an ultra-broadband amplified spontaneous emission (ASE) light source with 113.8 nm bandwidth (1446.2 to 1560.0 nm) by using a cascaded two-stage optical amplifier, which is consisted of semiconductor optical amplifier (SOA, 1st stage) and erbiumdoped fiber amplifier (EDFA, 2nd stage), when the output intensity is above -35 dBm/0.01 nm. And, the EDFA only uses a 3 m long erbium-doped fiber (EDF) with a 27 mW pumping power and SOA is driven at 200 mA bias current. Moreover, the proposed amplifier also can provide a broadband gain amplification of 114 nm in the wavelengths of 1464.0 and 1578.0 nm with the noise figure distribution of 6.8 to 8.1 dB.

Yeh, C. H.; Chow, C. W.; Chen, J. H.; Lu, S. S.

2012-11-01

179

Enhancing mammalian hearing by a balancing between spontaneous otoacoustic emissions and spatial coupling  

NASA Astrophysics Data System (ADS)

Nonlinear dynamics has provided significant insights into the origin of frequency discrimination and signal amplification underlying mammalian hearing. Existing signal amplification models, however, tend to ignore two basic known aspects of the hearing: spontaneous otoacoustic emissions (SOAEs) and intrinsic dynamical coupling in the cochlea. We construct and study a class of coupled-oscillator models to remedy this deficiency. Our analysis and computations reveal that the interplay and balance between the two aspects can naturally explain the phenomena of frequency discrimination and signal amplification and, more strikingly, the origin of hearing loss, all at a quantitative level. In the presence of SOAEs, there exists a critical coupling threshold below which hearing loss can occur, suggesting enhancement of coupling as a potentially effective therapeutic strategy to restore or even significantly enhance hearing.

Liu, Zonghua; Li, Baowen; Lai, Ying-Cheng

2012-04-01

180

Suppression of spontaneous emission and superradiance over macroscopic distances in media with negative refraction  

NASA Astrophysics Data System (ADS)

The possibility of negative optical path length in left-handed media (LHM) is shown to lead to complete suppression of spontaneous emission of an atom in front of a mirror with a layer of LHM. For the same reason two atoms put at the foci of a perfect lens formed by a parallel LHM slab [J. B. Pendry, Phys. Rev. Lett.8520003966] exhibit perfect subradiance and superradiance. It is shown that these effects occur over distances that can be orders of magnitude larger than the transition wavelength and are only limited by the propagation length within the free-space decay time of the atoms. Single- and two-atom decay rates are calculated from the Greens function of the electric field in the presence of a LHM and limitations as well as potential applications are discussed.

Kästel, Jürgen; Fleischhauer, Michael

2005-01-01

181

Start-up noise in 3-D self-amplified spontaneous emission  

SciTech Connect

The Self-Amplified-Spontaneous Emission (SASE) is receiving a renewed interest recently in connection with the proposal to build x-ray FEL facilities. A consistent theory of how the initial incoherent undulator radiation develops into an exponentially growing coherent signal was derived in 1-D case previously. How the theory could be extended to a 3-D case was also explained previously. In the case of the parallel electron beam, the problem was explicitly solved previously. In particular, the equivalent noise power was identified as the undulator radiation in one gain length. In this paper, we study how the result should be modified when the electrons` angular divergence is taken into account. We find that the equivalent noise power is the portion of the undulator power within the coherent phase space area, a result that should have been expected.

Kim, Kwang-Je

1996-08-01

182

Suppression of spontaneous emission and superradiance over macroscopic distances in media with negative refraction  

SciTech Connect

The possibility of negative optical path length in left-handed media (LHM) is shown to lead to complete suppression of spontaneous emission of an atom in front of a mirror with a layer of LHM. For the same reason two atoms put at the foci of a perfect lens formed by a parallel LHM slab [J. B. Pendry, Phys. Rev. Lett. 85, 3966 (2000)] exhibit perfect subradiance and superradiance. It is shown that these effects occur over distances that can be orders of magnitude larger than the transition wavelength and are only limited by the propagation length within the free-space decay time of the atoms. Single- and two-atom decay rates are calculated from the Greens function of the electric field in the presence of a LHM and limitations as well as potential applications are discussed.

Kaestel, Juergen; Fleischhauer, Michael [Fachbereich Physik, Technische Universitaet Kaiserslautern, D-67663 Kaiserslautern (Germany)

2005-01-01

183

Photoexcitation dynamics in polyfluorene-based thin films: Energy transfer and amplified spontaneous emission  

NASA Astrophysics Data System (ADS)

The dynamics of photoexcitations in thin films based on the polymer poly(9,9-dioctylfluorene) is investigated by a combination of stationary spectroscopy, femtosecond absorption and time-resolved fluorescence measurements. Excitation energy transfer to keto defects within the polyfluorene host matrix and to guest molecules in a dye doped host/guest system is observed and modeled by rate equations. Characteristic parameters for the exciton dynamics are extracted. At high excitation densities, amplified spontaneous emission from the edge of the films arises accompanied by strongly nonexponential signal decay in transient absorption. The underlying coupled excited-state and photon dynamics in the films are included in the model, which describes the measured data consistently for various excitation densities.

Marciniak, Henning; Teicher, Maik; Scherf, Ullrich; Trost, Sara; Riedl, Thomas; Lehnhardt, Marcus; Rabe, Torsten; Kowalsky, Wolfgang; Lochbrunner, Stefan

2012-06-01

184

Amplified spontaneous emission in polymer films doped with a perylenediimide derivative  

NASA Astrophysics Data System (ADS)

The presence of amplified spontaneous emission (ASE) by optical pump in polystyrene films doped with N,N?-di(10-nonadecyl)perylene-3,4:9,10-tetracarboxylic diimide (PDI-N) in a range of PDI-N concentrations between 0.25 and 5 wt. % is reported. Gain coefficients up to 10 cm-1, at a pump intensity of 74 kW/cm2, were obtained. The lowest thresholds (˜15 kW/cm2) and largest photostabilities measured at 50% (˜50 min, i.e., 30,000 pump pulses) were obtained for concentrations up to 1 wt. %. The observation of an increase in the ASE threshold and a decrease in the photostability for larger concentrations is attributed to the presence of aggregated species.

Calzado, Eva M.; Villalvilla, José M.; Boj, Pedro G.; Quintana, José A.; Gómez, Rafael; Segura, José L.; Díaz García, María A.

2007-06-01

185

Three-dimensional analysis of harmonic generation in self-amplified spontaneous emission.  

SciTech Connect

In a high-gain free-electron laser, strong bunching at the fundamental wavelength can drive substantial harmonic bunching and sizable power levels at the harmonic frequencies. In this paper, we investigate the three-dimensional evolution of the harmonic fields based on the coupled Maxwell-Vlasov equations that take into account the nonlinear harmonic interaction. Each harmonic field is the sum of a self-amplified term and a term driven by the nonlinear harmonic interaction. In the exponential gain regime, the growth rate of the dominant nonlinear term is much faster than that of the self-amplified harmonic field. As a result, the gain length and the transverse profile of the first few harmonics are completely determined by those of the fundamental. A percentage of the fundamental power level is found at the third harmonic frequency right before saturation for the current self-amplified spontaneous emission projects.

Huang, Z.; Kim, K.-J.

1999-09-01

186

Controlling air emissions from incinerators  

SciTech Connect

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.

Foisy, M.B.; Li, R.; Chattapadhyay, A. [Malcolm Pirnie, Inc., White Plains, NY (United States)] [and others

1994-04-01

187

Surface plasmon-enhanced spontaneous emission rate in an organic light-emitting device structure: Cathode structure for plasmonic application  

Microsoft Academic Search

The surface plasmon-enhanced spontaneous emission based on an organic light-emitting device is reported in this paper. For surface plasmon localization, silver nanoparticles were thermally deposited in a high vacuum on cathode that had a 1-nm-thick LiF spacer. Since plasmons provide a strong oscillator decay channel, time-resolved photoluminescence (PL) results displayed a 1.75-fold increased emission rate, and continuous wave PL results

Ki Youl Yang; Kyung Cheol Choi; Chi Won Ahn

2009-01-01

188

New Experimental Method of Investigation the Rare Nuclear Transformations Accompanying Atomic Processes:. Bremsstrahlung Emission in Spontaneous Fission of 252Cf  

NASA Astrophysics Data System (ADS)

High energy bremsstrahlung emission during spontaneous fission of 252Cf is observed. The new experimental method to detect rare coincident events by digital storage oscilloscope is used. The ?-rays with energies up to 60 MeV have been measured (by a BGO detector) in coincidence with neutrons detected by a plastic scintillator. The determination of ?-ray emission probability up to the value of about 8 × 10-9event/(MeV × fission) at E?= 60 MeV is achieved.

Eremin, N. V.; Paskhalov, A. A.; Markochev, S. S.; Tsvetkov, E. A.; Mandaglio, G.; Manganaro, M.; Fazio, G.; Giardina, G.; Romaniuk, M. V.

189

Enhanced Spontaneous Emission of CdSe\\/ZnSe Quantum Dots in Monolithic II-VI Pillar Microcavities  

Microsoft Academic Search

The emission properties of CdSe\\/ZnSe quantum dots in ZnSe-based pillar microcavities are studied. All-epitaxial cavities made of ZnSSe and MgS\\/ZnCdSe superlattices with a single quantum-dot sheet embedded have been grown by molecular-beam epitaxy. Pillar structures with diameters down to 500 nm have been realized by focused-ion-beam etching. As evidence for the Purcell effect a pronounced enhancement of the spontaneous emission

H. Lohmeyer; K. Sebald; C. Kruse; D. Hommel; J. Gutowski

2007-01-01

190

Mesoscopic entanglement induced by spontaneous emission in solid-state quantum optics.  

PubMed

Implementations of solid-state quantum optics provide us with devices where qubits are placed at fixed positions in photonic or plasmonic one-dimensional waveguides. We show that solely by controlling the position of the qubits and with the help of a coherent driving, collective spontaneous decay may be engineered to yield an entangled mesoscopic steady state. Our scheme relies on the realization of pure superradiant Dicke models by a destructive interference that cancels dipole-dipole interactions in one dimension. PMID:23473122

González-Tudela, Alejandro; Porras, Diego

2013-02-20

191

Towards the two-dimensional imaging of spontaneous ultra-weak photon emission from microbial, plant and animal cells  

PubMed Central

Two-dimensional imaging of spontaneous ultra-weak photon emission was measured in the yeast cells, Arabidopsis plant and the human hand using highly sensitive charge coupled device (CCD) camera. For the first time, the detail analysis of measuring parameters such as accumulation time and binning is provided with the aim to achieve two-dimensional images of spontaneous ultra-weak photon emission of good quality. We present data showing that using a hardware binning with binning factor 4 × 4, the accumulation time decreases in the following order: yeast cells (30?min) > the human hand (20?min) > Arabidopsis plant (10?min). Analysis of measuring parameters provides a detailed description of standard condition to be used for two-dimensional spontaneous ultra-weak photon imaging in microbes, plants and animals. Thus, CCD imaging can be employed as a unique tool to examine the oxidative state of the living organism with the application in microbiological, plant and medical research.

Prasad, Ankush; Pospisil, Pavel

2013-01-01

192

Difference values of spontaneous emission rate of a single-impurity molecule of pentacene in biaxial p-terphenyl crystal  

Microsoft Academic Search

The spontaneous emission rate of a single-impurity molecule in a birefringent host crystal depends on the angles between the transition dipole moment and the principal axes of the dielectric (permittivity) tensor as well as on the main dielectric constants of a host crystal. The transition dipole moment of a single pentacene impurity in p-terphenyl crystal may have four different orientations

Inna Rebane

2007-01-01

193

Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line  

Microsoft Academic Search

Exponential growth of self-amplified spontaneous emission at 530nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

N. D. Arnold; J. Attig; G. Banks; R. Bechtold; K. Beczek; C. Benson; S. Berg; W. Berg; S. G Biedron; J. A Biggs; M. Borland; K. Boerste; M. Bosek; W. R Brzowski; J. Budz; J. A Carwardine; P. Castro; Y.-C Chae; S. Christensen; C. Clark; M. Conde; E. A Crosbie; G. A Decker; R. J Dejus; H. DeLeon; P. K Den Hartog; B. N Deriy; D. Dohan; P. Dombrowski; D. Donkers; C. L Doose; R. J Dortwegt; G. A Edwards; Y. Eidelman; M. J Erdmann; J. Error; R. Ferry; J. Forrestal; H. Freund; H. Friedsam; J. Gagliano; W. Gai; J. N Galayda; R. Gerig; R. L Gilmore; E. Gluskin; G. A Goeppner; J. Goetzen; C. Gold; A. J Gorski; A. E Grelick; M. W Hahne; S. Hanuska; K. C Harkay; G. Harris; A. L Hillman; R. Hogrefe; J. Hoyt; Z. Huang; J. M Jagger; W. G Jansma; M. Jaski; S. J Jones; R. T Keane; A. L Kelly; C. Keyser; K.-J Kim; S. H Kim; M. Kirshenbaum; J. H Klick; K. Knoerzer; R. J Koldenhoven; M. Knott; S. Labuda; R. Laird; J. Lang; F. Lenkszus; E. S Lessner; J. W Lewellen; Y. Li; R. M Lill; A. H Lumpkin; O. A Makarov; G. M Markovich; M. McDowell; W. P McDowell; P. E McNamara; T. Meier; D. Meyer; W. Michalek; S. V. Milton; H. Moe; E. R Moog; L. Morrison; A. Nassiri; J. R Noonan; R. Otto; J. Pace; S. J Pasky; J. M Penicka; A. F Pietryla; G. Pile; C. Pitts; J. Power; T. Powers; C. C. Putnam; A. J Puttkammer; D. Reigle; L. Reigle; D. Ronzhin; E. R Rotela; E. F Russell; V. Sajaev; S. Sarkar; J. C Scapino; K. Schroeder; R. A Seglem; N. S Sereno; S. K Sharma; J. F Sidarous; O. Singh; T. L Smith; R. Soliday; G. A Sprau; S. J Stein; B. Stejskal; V. Svirtun; L. C Teng; E. Theres; K. Thompson; B. J Tieman; J. A Torres; E. M Trakhtenberg; G. Travish; G. F Trento; J. Vacca; I. B Vasserman; N. A Vinokurov; D. R Walters; J. Wang; X. J Wang; J. Warren; S. Wesling; D. L Weyer; G. Wiemerslage; K. Wilhelmi; R. Wright; D. Wyncott; S. Xu; B.-X. Yang; W. Yoder; R. B Zabel

2001-01-01

194

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

Microsoft Academic Search

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

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

195

Effective gain clamping of semiconductor optical amplifiers by injecting broad-band self-generated amplified spontaneous emission  

Microsoft Academic Search

A conventional SOA is effectively gain-clamped by the injection of self-generated broadband amplified spontaneous emission. The gain is clamped up to an input power of-2 dBm with an output power in excess of 11 dBm.

J. M. Oh; D. Lee

2007-01-01

196

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

Microsoft Academic Search

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

S. Roshan Entezar

2009-01-01

197

Simple method for the temporal characterization of amplified spontaneous emission in femtosecond terawatt Ti:sapphire lasers  

Microsoft Academic Search

We have analyzed the temporal characteristics of amplified spontaneous emission (ASE) in femtosecond terawatt Ti:sapphire lasers by using a simple method based on fast photodiodes. Instead of measuring ASE directly with fast photodiodes, we created a narrow gap in the spectrum of seed pulses and, after amplification, detected the pure ASE signal through the gap by using a fast photodiode

Yong-Ho Cha; Yong-Woo Lee; Sung Mo Nam; Jae Min Han; Yong Joo Rhee; Byung Duk Yoo; Byoung Chul Lee; Young Uk Jeong

2007-01-01

198

Observation and analysis of self-amplified spontaneous emission at the APS low-energy undulator test line  

NASA Astrophysics Data System (ADS)

Exponential growth of self-amplified spontaneous emission at 530nm was first experimentally observed at the Advanced Photon Source low-energy undulator test line in December 1999. Since then, further detailed measurements and analysis of the results have been made. Here, we present the measurements and compare these with calculations based on measured electron beam properties and theoretical expectations.

Arnold, N. D.; Attig, J.; Banks, G.; Bechtold, R.; Beczek, K.; Benson, C.; Berg, S.; Berg, W.; Biedron, S. G.; Biggs, J. A.; Borland, M.; Boerste, K.; Bosek, M.; Brzowski, W. R.; Budz, J.; Carwardine, J. A.; Castro, P.; Chae, Y.-C.; Christensen, S.; Clark, C.; Conde, M.; Crosbie, E. A.; Decker, G. A.; Dejus, R. J.; DeLeon, H.; Den Hartog, P. K.; Deriy, B. N.; Dohan, D.; Dombrowski, P.; Donkers, D.; Doose, C. L.; Dortwegt, R. J.; Edwards, G. A.; Eidelman, Y.; Erdmann, M. J.; Error, J.; Ferry, R.; Flood, R.; Forrestal, J.; Freund, H.; Friedsam, H.; Gagliano, J.; Gai, W.; Galayda, J. N.; Gerig, R.; Gilmore, R. L.; Gluskin, E.; Goeppner, G. A.; Goetzen, J.; Gold, C.; Gorski, A. J.; Grelick, A. E.; Hahne, M. W.; Hanuska, S.; Harkay, K. C.; Harris, G.; Hillman, A. L.; Hogrefe, R.; Hoyt, J.; Huang, Z.; Jagger, J. M.; Jansma, W. G.; Jaski, M.; Jones, S. J.; Keane, R. T.; Kelly, A. L.; Keyser, C.; Kim, K.-J.; Kim, S. H.; Kirshenbaum, M.; Klick, J. H.; Knoerzer, K.; Koldenhoven, R. J.; Knott, M.; Labuda, S.; Laird, R.; Lang, J.; Lenkszus, F.; Lessner, E. S.; Lewellen, J. W.; Li, Y.; Lill, R. M.; Lumpkin, A. H.; Makarov, O. A.; Markovich, G. M.; McDowell, M.; McDowell, W. P.; McNamara, P. E.; Meier, T.; Meyer, D.; Michalek, W.; Milton, S. V.; Moe, H.; Moog, E. R.; Morrison, L.; Nassiri, A.; Noonan, J. R.; Otto, R.; Pace, J.; Pasky, S. J.; Penicka, J. M.; Pietryla, A. F.; Pile, G.; Pitts, C.; Power, J.; Powers, T.; Putnam, C. C.; Puttkammer, A. J.; Reigle, D.; Reigle, L.; Ronzhin, D.; Rotela, E. R.; Russell, E. F.; Sajaev, V.; Sarkar, S.; Scapino, J. C.; Schroeder, K.; Seglem, R. A.; Sereno, N. S.; Sharma, S. K.; Sidarous, J. F.; Singh, O.; Smith, T. L.; Soliday, R.; Sprau, G. A.; Stein, S. J.; Stejskal, B.; Svirtun, V.; Teng, L. C.; Theres, E.; Thompson, K.; Tieman, B. J.; Torres, J. A.; Trakhtenberg, E. M.; Travish, G.; Trento, G. F.; Vacca, J.; Vasserman, I. B.; Vinokurov, N. A.; Walters, D. R.; Wang, J.; Wang, X. J.; Warren, J.; Wesling, S.; Weyer, D. L.; Wiemerslage, G.; Wilhelmi, K.; Wright, R.; Wyncott, D.; Xu, S.; Yang, B.-X.; Yoder, W.; Zabel, R. B.

2001-12-01

199

Multilevel quantum electrodynamic calculation of spontaneous emission and small signal gain in high voltage free electron lasers  

Microsoft Academic Search

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

C. S. Chang; H. U. Fluhler

1991-01-01

200

Prolonged spontaneous emission and dephasing of localized excitons in air-bridged carbon nanotubes.  

PubMed

The bright exciton emission of carbon nanotubes is appealing for optoelectronic devices and fundamental studies of light-matter interaction in one-dimensional nanostructures. However, to date, the photophysics of excitons in carbon nanotubes is largely affected by extrinsic effects. Here we perform time-resolved photoluminescence measurements over 14 orders of magnitude for ultra-clean carbon nanotubes bridging an air gap over pillar posts. Our measurements demonstrate a new regime of intrinsic exciton photophysics with prolonged spontaneous emission times up to T1=18 ns, about two orders of magnitude better than prior measurements and in agreement with values hypothesized by theorists about a decade ago. Furthermore, we establish for the first time exciton decoherence times of individual nanotubes in the time domain and find fourfold prolonged values up to T2=2.1 ps compared with ensemble measurements. These first observations motivate new discussions about the magnitude of the intrinsic dephasing mechanism while the prolonged exciton dynamics is promising for applications. PMID:23845935

Sarpkaya, Ibrahim; Zhang, Zhengyi; Walden-Newman, William; Wang, Xuesi; Hone, James; Wong, Chee W; Strauf, Stefan

2013-01-01

201

Prolonged spontaneous emission and dephasing of localized excitons in air-bridged carbon nanotubes  

NASA Astrophysics Data System (ADS)

The bright exciton emission of carbon nanotubes is appealing for optoelectronic devices and fundamental studies of light-matter interaction in one-dimensional nanostructures. However, to date, the photophysics of excitons in carbon nanotubes is largely affected by extrinsic effects. Here we perform time-resolved photoluminescence measurements over 14 orders of magnitude for ultra-clean carbon nanotubes bridging an air gap over pillar posts. Our measurements demonstrate a new regime of intrinsic exciton photophysics with prolonged spontaneous emission times up to T1=18?ns, about two orders of magnitude better than prior measurements and in agreement with values hypothesized by theorists about a decade ago. Furthermore, we establish for the first time exciton decoherence times of individual nanotubes in the time domain and find fourfold prolonged values up to T2=2.1?ps compared with ensemble measurements. These first observations motivate new discussions about the magnitude of the intrinsic dephasing mechanism while the prolonged exciton dynamics is promising for applications.

Sarpkaya, Ibrahim; Zhang, Zhengyi; Walden-Newman, William; Wang, Xuesi; Hone, James; Wong, Chee W.; Strauf, Stefan

2013-07-01

202

Plasmonic Structures for CMOS Photonics and Control of Spontaneous Emission.  

National Technical Information Service (NTIS)

In this project, we have (i) demonstrated modulation of the refractive index n >1 at near infrared frequencies during field effect gating of conducting oxide (ITO) thin films for switching applications; (ii) demonstrated record low coupling loss from sili...

H. A. Atwater

2013-01-01

203

Diesel engine emissions: A timing control approach  

Microsoft Academic Search

Growing demands are being placed on the diesel engine industry to lower emission levels. A key ingredient in emissions reduction is precise injection pump to engine timing control. This paper outlines a unique approach to dynamically time an injection pump to an engine during its initial test cycle while developing the ability to repeat the timing function using the same

P. T. Henderson; D. Wells; M. Haddox

1987-01-01

204

Dry scrubbing controls kiln emissions  

Microsoft Academic Search

The Clean Air Act Amendments of 1990 require that industrial emissions be significantly reduced by 2000, and some states require reductions with earlier deadlines. This is a critical time for US ceramic industries. There are only a few ways to conform to the upcoming regulations, singularly or in combination: change the composition of raw materials, change the way kilns are

1994-01-01

205

Structure-Property Relationship of Amplified Spontaneous Emission in Organic Semiconductor Materials: TPD, DPABP, and NPB.  

PubMed

N,N'-Diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) was demonstrated to be suitable for stimulated emission in doping and nondoping planar waveguide structure, but the mechanism for its lasing is of ambiguity. With the aim of providing a microsscopic picture for its lasing, we performed a combined experimental and theortical investigation of the absorption, photoluminescence (PL), and stimulated emission of TPD and other two similar molecules: 1,4-bis (diphenylamino)biphenyl (DPABP) and N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4?-diamine (NPB). It was found that DPABP shows the same amplified spontaneous emission (ASE) characteristics as TPD, but NPB did not. In theory, density functional theory (DFT) and Franck-Condon Principle were used to analyze the molecular geometry in the electronic ground state as well as the optically excited state and the vibrational levels in electronic ground state, respectively. The calculation results show that for TPD and DPABP, several strongly elongated high-frequency modes (1199-1664 cm(-1)) in the carbon rings contribute to the distinct first vibronic sideband in the PL spectra, which form an effective four-level system for lasing. For NPB, when the peripheral toluene or benzene is replaced with naphthyl, a number of strongly elongated low-frequency modes (11-689 cm(-1)) deriving from naphthyl leads to a series of energy sublevels, which destroys the four-level system. Our results provided a new insight and better understanding into the lasing of organic molecules. PMID:24032429

Wu, Zhaoxin; Ma, Lin; Liu, Peng; Zhou, Caihua; Ning, Shuya; El-Shafei, Ahmed; Zhao, Xiang; Hou, Xun

2013-10-16

206

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

NASA Astrophysics Data System (ADS)

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 new finite-volume code for the numerical simulation of a continuously stratified liquid in a differentially heated rotating annulus, we here investigate whether such an experiment might be useful for studies of spontaneous imbalance. A major problem was the identification of experimental parameters yielding an atmosphere-like regime where the Brunt-Vaisala frequency is larger than the inertial frequency, so that energy transport by the lowest-frequency waves is predominantly horizontal while high-frequency GWs transport energy vertically. We show that this is indeed the case for a wide and shallow annulus with relatively large temperature difference between the inner and outer cylinder walls. We also show that this set-up yields a conspicuous signal in the horizontal divergence field close to the meandering jet. Various analyses support the notion that this signal is predominantly due to GWs superposed on a geostrophic flow. 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 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

Borchert, S.; Achatz, U.; Rieper, F.; Fruman, M. D.

2012-04-01

207

Formalising the informal?: Dynamic social order, bottom-up social control, and spontaneous normative relations  

Microsoft Academic Search

The right framework for studying normative issues in infosociety and MAS is that of deliberate or spontaneous social order, and intended or unintended, centralised or decentralised forms of social control. For effectively supporting human cooperation it is necessary to \\

Cristiano Castelfranchi

2003-01-01

208

Gaseous Emissions from Plants in Controlled Environments.  

National Technical Information Service (NTIS)

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...

D. T. Dubay

1988-01-01

209

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

NASA Astrophysics Data System (ADS)

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.

Razzaghi, D.; Hajiesmaeilbaigi, F.; Ruzbehani, M.

2012-08-01

210

Effect of confined radiation field on spontaneous-emission lifetime in vacuum-deposited fluorescent dye films  

NASA Astrophysics Data System (ADS)

Spontaneous emission lifetimes of fluorescent dye layers in front of a metallic mirror were observed using a picosecond time-resolved fluorescence measurement system. Multilayer thin-film samples composed of glass substrate/indium—tinoxide layer/organic spacer layer/emission dye layer/organic spacer layer/MgAg mirror were prepared with vacuum-vapor deposition. The distance between an MgAg mirror and an emission dye layer was varied from 25 to 180 nm. The emission lifetime of the fluorescent dye layer largely depended on the MgAg mirror—emission layer distance and assumed a maximum at around 150 nm. A promising application of organic multilayer structures for the study on optical microcavity was suggested.

Tsutsui, T.; Adachi, C.; Saito, S.; Watanabe, M.; Koishi, M.

1991-07-01

211

Laser cooling of molecules by zero-velocity selection and single spontaneous emission  

SciTech Connect

A laser-cooling scheme for molecules is presented based on repeated cycle of zero-velocity selection, deceleration, and irreversible accumulation. Although this scheme also employs a single spontaneous emission as in [Raymond Ooi, Marzlin, and Audretsch, Eur. Phys. J. D 22, 259 (2003)], in order to circumvent the difficulty of maintaining closed pumping cycles in molecules, there are two distinct features which make the cooling process of this scheme faster and more practical. First, the zero-velocity selection creates a narrow velocity-width population with zero mean velocity, such that no further deceleration (with many stimulated Raman adiabatic passage (STIRAP) pulses) is required. Second, only two STIRAP processes are required to decelerate the remaining hot molecular ensemble to create a finite population around zero velocity for the next cycle. We present a setup to realize the cooling process in one dimension with trapping in the other two dimensions using a Stark barrel. Numerical estimates of the cooling parameters and simulations with density matrix equations using OH molecules show the applicability of the cooling scheme. For a gas at temperature T=1 K, the estimated cooling time is only 2 ms, with phase-space density increased by about 30 times. The possibility of extension to three-dimensional cooling via thermalization is also discussed.

Ooi, C. H. Raymond [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2010-11-15

212

Wavelength swept amplified spontaneous emission source for high speed retinal optical coherence tomography at 1060 nm.  

PubMed

The wavelength swept amplified spontaneous emission (ASE) source presented in this paper is an alternative approach to realize a light source for high speed swept source optical coherence tomography (OCT). ASE alternately passes a cascade of different optical gain elements and tunable optical bandpass filters. In this work we show for the first time a wavelength swept ASE source in the 1060 nm wavelength range, enabling high speed retinal OCT imaging. We demonstrate ultra-rapid retinal OCT at a line rate of 170 kHz, a record sweep rate at 1060 nm of 340 kHz with 70 nm full sweep width, enabling an axial resolution of 11 ?m. Two different implementations of the source are characterized and compared to each other. The last gain element is either a semiconductor optical amplifier or an Ytterbium-doped fibre amplifier enabling high average output power of >40 mW. Various biophotonic imaging examples provide a wide range of quality benchmarks achievable with such sources. PMID:21780301

Eigenwillig, Christoph M; Klein, Thomas; Wieser, Wolfgang; Biedermann, Benjamin R; Huber, Robert

2010-11-12

213

Simulation and analytical study of amplified spontaneous emission in N2-lasers  

NASA Astrophysics Data System (ADS)

By applying the geometrical model of the gain coefficient and population, we managed to describe the amplified spontaneous emission (ASE) in a N2-laser. For this purpose, and also for verifying the geometrical modeling we used the earliest available experimental data for the N2-laser output energy ?ASE versus the laser excitation length reported by Leonard for a N2-laser operating at low gas pressure (20 Torr), with no preionization. The ASE output energy calculation was performed both numerically and analytically. Upon applying the full description of the gain coefficient and upper state population (with b-parameters?0), the numerical calculations found to explain the experimental measurements of the ?ASE versus excitation length correctly. For the analytical approach, we used the approximate expression for the gain and population (with b-parameters=0) for simplifying the calculation. The results corresponding to both cases are introduced. Furthermore, the calculated gain coefficient for describing the Leonard's experiment has been compared with our recent gain measurements in a N2-laser with corona preionization, and higher operational gas pressure (?100 Torr). This observation is indicating that while the gain coefficients in both experiments are obeying the generalized formulation of the gain coefficient, but the gain profile for the higher gas pressure is slightly higher than the case when the laser is operating at a low gas pressure. That is, the laser geometry still has the dominant contribution for the laser gain coefficient.

Sarikhani, S.; Hariri, A.

2013-01-01

214

Blue amplified spontaneous emission from a stilbenoid-compound-doped polymer optical fiber.  

PubMed

We report on the fabrication and characteristics of a step-index glass-clad polymer optical fiber that uses a novel fluorescent stilbenoid compound for lasing and amplification applications. The compound, 1, 4-bis(4-diphenyl-amino-styryl)-benzene, is specifically designed for the blue region of the spectrum and has a very high quantum yield of 0.85 in a solid-state polymer host and a large Stokes shift. Significant spectral narrowing and superlinear increase of output intensity are observed under photoexcitation at 355 nm, which are indicative of the occurrence of amplified spontaneous emission. By means of gain spectroscopy, a large optical gain of up to 36 cm(-1) at 494 nm has been obtained for the fiber when it is transversely photoexcited at 12 mJ/cm(2) . The waveguide loss has been measured to be 0.7 cm(-1) at 494 nm. The demonstration of high gain and low waveguide loss has favorable implications for the construction of a very compact, tunable coherent light source. PMID:18059742

Kobayashi, T; Blau, W J; Tillmann, H; Hörhold, H H

2001-12-15

215

Measurement of spectrum, bias dependence, and intensity of spontaneous emission in GaAs lasers  

SciTech Connect

Spontaneous emission spectra and intensity measurements are made on buried heterostructure lasers with transparent windows above the active stripe. The bias voltage V, where eV is the separation of quasi-Fermi levels, is determined from spectral measurements. The total luminescence intensity increases as exp(eV/nkT), where n changes from 1.0 to about 2 as V increases from 1.3 V to the threshold voltage of 1.415 V. The change in n is due primarily to saturation of the low-energy electron states as a result of electron degeneracy. The spectral determination of bias voltage is justified by the close agreement between the threshold voltage determined by spectral analysis and the voltage determined by extrapolation of directly measured light versus voltage data. Calibration of the absolute radiative rate with optical absorption data yields a predicted radiative recombination current of Jth/droughly-equal5.8 kA cm/sup -2/ ..mu..m/sup -1/, in reasonable agreement with empirical threshold data.

Henry, C.H.; Logan, R.A.; Bertness, K.A.

1981-07-01

216

Spontaneous emission of a photon: Wave-packet structures and atom-photon entanglement  

SciTech Connect

Spontaneous emission of a photon by an atom is described theoretically in three dimensions with the initial wave function of a finite-mass atom taken in the form of a finite-size wave packet. Recoil and wave-packet spreading are taken into account. The total atom-photon wave function is found in the momentum and coordinate representations as the solution of an initial-value problem. The atom-photon entanglement arising in such a process is shown to be closely related to the structure of atom and photon wave packets which can be measured in the coincidence and single-particle schemes of measurements. Two predicted effects, arising under the conditions of high entanglement, are anomalous narrowing of the coincidence wave packets and, under different conditions, anomalous broadening of the single-particle wave packets. Fundamental symmetry relations between the photon and atom single-particle and coincidence wave-packet widths are established. The relationship with the famous scenario of Einstein-Podolsky-Rosen is discussed.

Fedorov, M.V.; Efremov, M.A.; Kazakov, A.E. [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, 38 Vavilov Street, Moscow, 119991 (Russian Federation); Chan, K.W.; Eberly, J.H. [Center for Quantum Information and Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States); Law, C.K. [Department of Physics, Chinese University of Hong Kong, NT, Hong Kong (China)

2005-09-15

217

Economic growth and carbon emission control  

NASA Astrophysics Data System (ADS)

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

Zhang, Zhenyu

218

Spontaneous emission near the band edge of a three-dimensional photonic crystal: a fractional calculus approach  

NASA Astrophysics Data System (ADS)

We suggest a better mathematical method, fractional calculus, for studying the behavior of the atom-field interaction in photonic crystals. By studying the spontaneous emission of an atom in a photonic crystal with a one-band isotropic model, we found that the long-time inducing memory of the spontaneous emission is a fractional phenomenon. This behavior could be well described by fractional calculus. The results show no steady photon-atom bound state for the atomic resonant transition frequency lying in the proximity of the allowed band edge which was encountered in a previous study (Woldeyohannes and John 2003 J. Opt. B: Quantum Semiclass. Opt. 5 R43). The correctness of this result is validated by the 'cut-off smoothing' density of photon states (DOS) with fractional calculus. By obtaining a rigorous solution without the multiple-valued problem for the system, we show that the method of fractional calculus has a logically concise property.

Cheng, Szu-Cheng; Wu, Jing-Nuo; Tsai, Ming-Rung; Hsieh, Wen-Feng

2009-01-01

219

Quantum computing in the presence of spontaneous emission by a combined dynamical decoupling and quantum-error-correction strategy  

SciTech Connect

A method for quantum computation in the presence of spontaneous emission is proposed. The method combines strong and fast (dynamical decoupling) pulses and a quantum error correcting code that encodes n logical qubits into only n+1 physical qubits. Universal, fault-tolerant, quantum computation is shown to be possible in this scheme using Hamiltonians relevant to a range of promising proposals for the physical implementation of quantum computers.

Khodjasteh, K.; Lidar, D. A. [Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario, Canada M5S 1A7 (Canada); Chemical Physics Theory Group, Chemistry Department, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6 (Canada)

2003-08-01

220

Lifetime distribution of spontaneous emission from line antennas in two-dimensional quasi-periodic photonic crystals  

Microsoft Academic Search

We investigate the lifetime distribution functions of spontaneous emission from line antennas embedded in finite-size two-dimensional 12-fold quasi-periodic photonic crystals. Our calculations indicate that two-dimensional quasi-periodic crystals lead to the coexistence of both accelerated and inhibited decay processes. The decay behaviors of line antennas are drastically changed as the locations of the antennas are varied from the center to the

Xingsheng Xu; Haiyang Hu; Toshiki Yamada; Hongda Chen; Yiquan Wang

2008-01-01

221

Start-to-end simulation of self-amplified spontaneous emission free electron lasers from the gun through the undulator  

Microsoft Academic Search

It is widely appreciated that the performance of self-amplified spontaneous emission free-electron lasers (FELs) depends critically on the properties of the drive beam. In view of this, a multi-laboratory collaboration has explored methods and software tools for integrated simulation of the photoinjector, linear accelerator, bunch compressor, and FEL. Rather than create a single code to handle such a system, our

M. Borland; Y. C. Chae; P. Emma; J. W. Lewellen; V. Bharadwaj; W. M. Fawley; P. Krejcik; C. Limborg; S. V. Milton; H.-D. Nuhn; R. Soliday; M. Woodley

2002-01-01

222

Observation of Anomalously Large Spectral Bandwidth in a High-Gain Self-Amplified Spontaneous Emission Free-Electron Laser  

Microsoft Academic Search

Observation of ultra-wide bandwidth, up to a full width of 15%, 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 (?E\\/E ? 1.7%) emitted from the accelerator. Because of non- linear pulse compression during beam transport, a short, high current pulse with strong mismatch

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

223

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

SciTech Connect

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.

Matveev, Oleg I.; Omenetto, Nicolo' [EC, Joint Research Centre, Environment Institute, 21020 Ispra, Varese (Italy)

1995-04-01

224

Evaluation of lesion in a spontaneous osteonecrosis of the knee using 18 F-fluoride positron emission tomography  

Microsoft Academic Search

Positron-emission tomography (PET) imaging has several advantages over conventional scintigraphy, including a high spatial\\u000a resolution and the ability to quantify disease progression. Recently, 18F-fluoride PET has been applied to the evaluation of malignant tumors and musculoskeletal disorders. In our current study,\\u000a spontaneous osteonecrosis of the knee (SONK) was visualized using this technique. We determined whether PET images can reveal\\u000a SONK

Masato Aratake; Tayama Yoshifumi; Akira Takahashi; Ryohei Takeuchi; Tomio Inoue; Tomoyuki Saito

2009-01-01

225

Optically pumped amplified spontaneous emission in an ionic liquid-based polymer light-emitting electrochemical cell  

NASA Astrophysics Data System (ADS)

Optically pumped amplified spontaneous emission (ASE) is demonstrated in the active layer of the polymer light-emitting electrochemical cells (LECs). The active layer blend of the light-emitting polymer and the ionic liquid retained a high degree of transparency, enabling its use as an optical slab waveguide, allowing a low ASE threshold energy of 4.1 ?J cm-2 to be achieved. We also demonstrate a planar LEC that showed fast turn on, bright linear shape emission in the middle of the two contacts, and a relatively high current density of 36 A cm-2 with a low driving voltage of 6 V.

Sakanoue, Tomo; Sawabe, Kosuke; Yomogida, Yohei; Takenobu, Taishi; Seki, Shiro; Ono, Shimpei

2012-06-01

226

Enhanced Spontaneous Emission of CdSe/ZnSe Quantum Dots in Monolithic II-VI Pillar Microcavities  

NASA Astrophysics Data System (ADS)

The emission properties of CdSe/ZnSe quantum dots in ZnSe-based pillar microcavities are studied. All-epitaxial cavities made of ZnSSe and MgS/ZnCdSe superlattices with a single quantum-dot sheet embedded have been grown by molecular-beam epitaxy. Pillar structures with diameters down to 500 nm have been realized by focused-ion-beam etching. As evidence for the Purcell effect a pronounced enhancement of the spontaneous emission rate by a factor of up to 3.8 is found for quantum dots coupling to the fundamental mode of the cavities.

Lohmeyer, H.; Sebald, K.; Kruse, C.; Hommel, D.; Gutowski, J.

2007-04-01

227

Simulation of amplified spontaneous emission in high gain KrF laser amplifiers  

NASA Astrophysics Data System (ADS)

High gain KrF amplifier simulations require a realistic model of amplified spontaneous emission (ASE). We have recently developed an accurate three-dimensional time-dependent code to model ASE and parasitic oscillations in the Nike and Electra amplifiers. It currently includes arbitrary specular reflections at all of the walls and can be easily extended to nonspecular reflections. It can also simulate the ASE that would be seen by another amplifier stage or a camera located outside the amplifier module. The code approximates the ASE light by a discrete set of ordinates or quasi-plane waves whose propagation vectors represent all directions, but cluster preferentially around the amplifier axis, where the gain is highest. At each grid point, it updates the directed intensity by adding an analytic solution of the radiation transport equation within time increment ?t to the earlier intensity at a ``local look-back'' (LLB) point; this point is located a distance c?t back along the ordinate's characteristic direction. Because the LLB does not generally lie at a grid point, interpolation is required to calculate the earlier flux. Trilinear interpolation is simple and computationally fast, but it can introduce numerical spatial diffusion in the specific intensity. This diffusion is usually tolerable, but it can be a significant limitation if one attempts to treat a problem where the operating conditions or ASE viewing position favor a narrow range of directions that are not parallel to one of the Cartesian axes. For those conditions, we use an alternative interpolation scheme based on the flux-corrected transport algorithm, which previously has been used only to treat shock wave propagation in fluids. This article describes the code in detail, then shows ASE simulations illustrating the code's capabilities and the effects of transient excitation, diffusion, and gain narrowing.

Lehmberg, R. H.; Giuliani, J. L.

2003-07-01

228

Triple amplified spontaneous emissions from a conjugated copolymer BEHP-co-MEH-PPV in solution  

NASA Astrophysics Data System (ADS)

The spectral and laser properties of conjugated polymer {[2-[2?,5?-bis(2?-ethylhexyloxy)phenyl]-1,4-phenylenevinylene]-co-[2-methoxy-5-(2?-ethylhexyloxy)-1,4-phenylenevinylene]} (BEHP-co-MEH-PPV) in benzene had been studied and presented in this paper. BEHP-co-MEH-PPV was dissolved in benzene to form solutions of concentrations ranging from 1 mM to 10 mM. The absorption spectra had shown no new band when concentration increased; this indicates no dimer formation in these solutions for all concentrations mentioned above. The fluorescence spectra for the concentration 2.5 mM have shown two peaks at 560 nm and 600 nm, which could be attributed to monomer and excimer of MEH-PPV alone. At higher concentration (5 mM) the band at 560 nm almost disappeared and the band at 600 nm became dominant. At still higher concentration, the longer wavelength side of these spectra, there was a hump at 650 nm. So, this new band around 650 nm could be due to double excimer of MEH-PPV alone. When the laser pump power at 355 nm and concentration of above solution were suitably chosen, we observed amplified spontaneous emission (ASE) at 570 nm, 605 nm and 650 nm. These ASE peaks could arise from the monomer, excimer and double excimer states of MEH-PPV as a segment. To the best of our knowledge this is perhaps the first report on ASE from double excimer of the conjugated copolymer, BEHP-co-MEH-PPV, in liquid solution.

Ibnaouf, K. H.; Prasad, Saradh; Masilamani, V.; AlSalhi, M. S.; Mustapha, N.; Alyamani, A.

2013-09-01

229

Direction-dependent spontaneous emission from near-infrared quantum dots at the angular band edges of a three-dimensional photonic crystal  

Microsoft Academic Search

Engineering spontaneous emission from light emitters embedded within three-dimensional photonic crystals is of great significance in both fundamental research of quantum optics and applications of microphotonic devices. In this letter, we report on the effective modification of spontaneous emission from near-infrared PbSe quantum dots infiltrated in a three-dimensional woodpile polymeric photonic crystal through adjusting its angle-dependent stop gaps. A significant

Jiafang Li; Baohua Jia; Guangyong Zhou; Min Gu

2007-01-01

230

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

NASA Astrophysics Data System (ADS)

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.

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

231

Thermal emission control with periodic microstructures  

Microsoft Academic Search

In this thesis, the control of thermal emission with periodic microstructures is investigated. An important class of these structures, known as photonic crystals, are considered and Kirchhoff's law for photonic crystal films is discussed. Using fluctuational electrodynamics and a Green's function formalism, it is proved that Kirchhoff's law is obeyed for any photonic crystal films. This formalism allows the calculation

Sang Eon Han

2009-01-01

232

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...

233

Controllable optical emission spectroscopy plasma diagnostic system  

Microsoft Academic Search

Optical emission spectroscopy (OES) does not always produce signals useful for plasma diagnostics, including endpoint detection. Fluctuations in plasma power or deposition on walls, cause the OES signal to drift. To overcome such shortcomings, we have developed a method and tool that allows independent control of both electron energy (Ee) and density (ne). A description of the method and resulting

P. L. Stephan Thamban; Jimmy Hosch; Daniel Self; Matthew Goeckner

2008-01-01

234

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...

235

Variable emissivity laser thermal control system  

DOEpatents

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.

Milner, J.R.

1994-10-25

236

Analysing emission controls for power plants  

SciTech Connect

Congress is considering several bills specifically dealing with the issue of acid deposition and the control of SO/sub 2/ and NO /SUB X/ emissions. These bills are targeted principally at utility power plants. As a result, utility planners are now faced with the problem of how to evaluate and plan for the various proposals being made. Emission reduction evaluations and planning study results are dependent on the control technology cost and performance data, the utility's energy forecasts, and the size of the mandated or anticipated emission reductions. Changes in assumptions relative to those items can often outdate an extensive and complete analysis shortly after its completion. From a practical standpoint, due to the number of plants where various emission reduction technologies can be applied and the number of choices regarding when such actions should be taken, it is simply not possible to demonstrate that a chosen overall emission reduction plan is the best unless some sort of computerized optimization tool is used in the analysis. Not being able to demonstrate that a chosen plan is the best can unfavorably affect the confidence which the public places in the study, which in turn can limit the study's usefulness in determining what should be done.

Neumeyer, D.G.

1983-04-01

237

HIV controllers: a multifactorial phenotype of spontaneous viral suppression  

PubMed Central

A small minority of HIV-infected individuals, known as HIV controllers, is able to exert long-term control over HIV replication in the absence of treatment. Increasing evidence suggests that the adaptive immune system plays a critical role in this control but also that a combination of several host and/or viral factors, rather than a single cause, leads to this rare phenotype. Here, we review recent advances in the study of these remarkable individuals. We summarize the epidemiology and clinical characteristics of HIV controllers, and subsequently describe contributing roles of host genetic factors, innate and adaptive immune responses, and viral factors to this phenotype. We emphasize distinctive characteristics of HIV-specific CD4 T cell responses and of CD4 T cell subpopulations that are frequently found in HIV controllers. We discuss major controversies in the field and the relevance of the study of HIV controllers for the development of novel therapeutic strategies and vaccines.

Theze, Jacques; Chakrabarti, Lisa A.; Vingert, Benoit; Porichis, Filippos; Kaufmann, Daniel E.

2011-01-01

238

The emission of prompt neutrons from the spontaneous fission of 252No and 244Fm  

NASA Astrophysics Data System (ADS)

The neutron detector with 3He -filled counters placed in the focal plane of the VASSILISSA separator is used for measuring the average number and determining the multiplicity distribution of prompt neutrons from the spontaneous fission of heavy short-lived isotopes. The test reaction ensuremath {^{48}Ca}+{^{206}Pb}=2n+{^{252}No} is used for tuning the separator settings and calibrating the detector system with the spontaneous fission of the 252No . The average neutron number per 252No spontaneous fission event is as large as ensuremath bar{?}=4.06 ± 0.12 . The short-lived heavy isotope 244Fm , produced in the complete fusion reaction 40Ar + 206Pb , is investigated. The average number of neutrons per spontaneous fission of 244Fm from the experimental data ( ensuremath bar{?}=3.3 ± 0.3 is determined for the first time.

Svirikhin, A. I.; Andreev, A. V.; Dushin, V. N.; Chelnokov, M. L.; Chepigin, V. I.; Gupta, M.; Isaev, A. V.; Izosimov, I. N.; Katrasev, D. E.; Kuznetsov, A. N.; Malyshev, O. N.; Mullins, S.; Popeko, A. G.; Sokol, E. A.; Yeremin, A. V.

2012-09-01

239

Ternary particle emission in spontaneous fission of 250Cf and 252Cf and in neutron induced fission of 249Cf and 251Cf  

NASA Astrophysics Data System (ADS)

The emission probabilities and the energy distributions of tritons, ? and 6He particles emitted in the spontaneous ternary fission (zero excitation energy) of 250Cf and 252Cf and in the cold neutron induced fission (excitation energy ?6.5 MeV) of 249Cf and 251Cf are determined. The particle identification was done with suited ?E-E telescope detectors, at the IRMM (Geel, Belgium) for the spontaneous fission and at the ILL (Grenoble, France) for the neutron induced fission measurements. Hence particle emission characteristics of the fissioning systems 250Cf and 252Cf are obtained at zero and at about 6.5 MeV excitation energies. While the triton emission probability is hardly influenced by the excitation energy, the 4He and 6He emission probability in spontaneous fission is higher than for neutron induced fission. This can be explained by the strong influence of the cluster preformation probability on the ternary particle emission probability.

Vermote, S.; Wagemans, C.; Serot, O.; Heyse, J.; van Gils, J.; Soldner, T.; Geltenbort, P.; Almahamid, I.; Tian, G.; Rao, L.

2010-06-01

240

Enhanced control of mercury emissions through modified speciation.  

National Technical Information Service (NTIS)

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 measur...

C. D. Livengood M. H. Mendelsohn

1997-01-01

241

Spontaneous cognitive strategies for the control of clinical pain and stress  

Microsoft Academic Search

The spontaneous cognitive strategies employed by 75 patients undergoing dental extractions or mandibular block injections were elicited using a structured interview. Interest focused on the relationship between these strategies and several personality variables, including state and trait anxiety, locus of control, and absorption. In addition, the effect of strategy utilization on perceived pain and stress was assessed. Fourty-four percent of

John F. Chaves; Jude M. Brown

1987-01-01

242

Carbon nanotubes and optical confinement: controlling light emission in nanophotonic devices  

Microsoft Academic Search

We report here recent progress in nanophotonics with single-wall carbon nanotubes (SWNTs). A photonic model structure, the planar lambda\\/2-microcavity, modifies the photonic density of modes at the location of the embedded SWNTs. As a result, the radiative properties of the SWNTs are modified due to the enhancement or inhibition of the microcavity-controlled spontaneous emission (scattering) rate. We use single-molecule optical

Mathias Steiner; Fengnian Xia; Huihong Qian; Yu-Ming Lin; Achim Hartschuh; Alfred J. Meixner; Phaedon Avouris

2008-01-01

243

Lifetime distribution of spontaneous emission from line antennas in two-dimensional quasi-periodic photonic crystals  

NASA Astrophysics Data System (ADS)

We investigate the lifetime distribution functions of spontaneous emission from line antennas embedded in finite-size two-dimensional 12-fold quasi-periodic photonic crystals. Our calculations indicate that two-dimensional quasi-periodic crystals lead to the coexistence of both accelerated and inhibited decay processes. The decay behaviors of line antennas are drastically changed as the locations of the antennas are varied from the center to the edge in quasi-periodic photonic crystals and the location of transition frequency is varied.

Xu, Xingsheng; Hu, Haiyang; Yamada, Toshiki; Chen, Hongda; Wang, Yiquan

2008-03-01

244

EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Distributed extraction of amplified spontaneous emission from a randomly inhomogeneous active medium  

NASA Astrophysics Data System (ADS)

This paper investigates the dynamics of amplified spontaneous x-ray emission escaping from a randomly inhomogeneous plasma active medium through its ends and lateral surface. It is shown that the scattering of radiation by fluctuations in the dielectric permittivity, ?˜, can be utilized to extract energy through the lateral surface of the active medium. The radiant intensity is maximal in an off-axis direction in this case. When both regular refraction and scattering by ?˜ are operating, the distributed extraction of the light is determined by that effect which has the smaller characteristic length (i.e., the scattering length or the refraction length).

Starikov, F. A.

1993-05-01

245

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

SciTech Connect

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.

Schleich, W.; Scully, M.O.

1988-02-15

246

784-nm amplified spontaneous emission from Tm3+-doped fluoride glass fiber pumped by an 1120-nm fiber laser.  

PubMed

We report 784-nm (1G4 --> 3H5 transition) amplified spontaneous emission (ASE) from Tm3+-doped fluoride (ZrF4-BaF2-LaF3-AlF3-NaF) glass fiber pumped by an 1120-nm fiber laser. To our best knowledge, this is the first report of 784-nm (1G4 --> 3H5 transition) ASE in a Tm3+-doped fluoride fiber laser. Its effects on a 480-nm (1G4 --> 3H6 transition) blue laser were also discussed. PMID:15751881

Qin, Guanshi; Huang, Shenghong; Feng, Yan; Shirakawa, A; Ueda, Ken-ichi

2005-02-01

247

Systematics of spontaneous emission of intermediate mass fragments from heavy nuclei  

SciTech Connect

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.

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

1986-07-01

248

Mobility control through spontaneous formation of nanoparticle stabilized emulsions  

NASA Astrophysics Data System (ADS)

We report on measurements of the flow pattern and in-situ saturations when n-octane displaces a brine in which surface treated silica nanoparticles are dispersed. The nanoparticles are known to stabilize octane-in-water emulsions. We find that the displacement front is more spatially uniform, and with a later breakthrough when compared to a control displacement with no in-situ nanoparticles. Pressure measurements during the displacement are consistent with generation of a viscous phase such as an emulsion. These observations suggest that a nanoparticle stabilized emulsion is formed during the displacement which acts to suppress the viscous instability. We argue that generation of droplets of nonwetting phase occurs at the leading edge of all drainage displacements. The droplets rejoin the bulk phase in the absence of stabilizing agents, but are preserved when nanoparticles adhere to the fluid/fluid interface.

DiCarlo, D. A.; Aminzadeh, B.; Roberts, M.; Chung, D. H.; Bryant, S. L.; Huh, C.

2011-12-01

249

Effect of Colorpuncture on Spontaneous Photon Emission in a Subject Suffering from Multiple Sclerosis  

Microsoft Academic Search

Spontaneous photon signals from four sites of a human subject suffering from multiple sclerosis were detected in 3600 bins of 50 milliseconds by a photo multiplier sensitive in 160–630nm, before and after a session of colorpuncture treatment. Measurements were made in 22 sessions over a period of 9 months. Each signal was analyzed to determine if it was a quantum

RP Bajpai; M Drexel

2008-01-01

250

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...

251

MINIMISATION OF NOx EMISSION BY FLAME TEMPERATURE CONTROL  

Microsoft Academic Search

Emission control technology has advanced to an extent whereby pollutant levels are now controlled by legislation. Techniques for controlling emissions vary and include improved fuel mixture preparation, multi stage combustion, exhaust gas recirculation, inhibitors such as ammonia and other techniques which reduce the intensity of combustion and hence flame temperature.This paper examines ways in which ultra low NOx, emission combustors

S. A. MACGREGOR; N. SYRED; T. C. CLAYPOLE

1987-01-01

252

Photogeneration of charge carrier correlated with amplified spontaneous emission in single crystals of a thiophene/phenylene co-oligomer.  

PubMed

Thiophene/phenylene co-oligomers have substantial promise for the use of not only organic electronics but also organic optical devices. However, considerably less is known about the correlation between their optical and optoelectronic properties. We have investigated the charge carrier generation in 1,4-bis(5-phenylthiophen-2-yl)benzene (AC5) single crystals by flash-photolysis time-resolved microwave conductivity (TRMC) and transient absorption spectroscopy (TAS). It was found that the dependence of photocarrier generation efficiency on excitation photon density differed from that of emission efficiency once amplified spontaneous emission (ASE) and resultant spectrally narrowed emission occur upon exposure to 355 nm. In contrast, the dependences of emission and photocarrier generation efficiencies were identical when ASE was not involved at a different excitation wavelength (193 nm). An approximated analytical solution of rate equation considering ASE or singlet-singlet annihilation was applied to the experiments, exhibiting good agreement. On the basis of TRMC, TAS, and extinction coefficient of radical cation assessed by pulse radiolysis, the minimum charge carrier mobility was estimated, without electrodes, to be 0.12 cm(2) V(-1) s(-1). The dynamics of charge carrier and triplet excited state is discussed, accompanying with examination by time-dependent density functional theory. The present work would open the way to a deeper understanding of the fate of excited state in optically robust organic semiconducting crystals. PMID:20387943

Saeki, Akinori; Seki, Shu; Shimizu, Yasuhiro; Yamao, Takeshi; Hotta, Shu

2010-04-01

253

Photogeneration of charge carrier correlated with amplified spontaneous emission in single crystals of a thiophene/phenylene co-oligomer  

NASA Astrophysics Data System (ADS)

Thiophene/phenylene co-oligomers have substantial promise for the use of not only organic electronics but also organic optical devices. However, considerably less is known about the correlation between their optical and optoelectronic properties. We have investigated the charge carrier generation in 1,4-bis(5-phenylthiophen-2-yl)benzene (AC5) single crystals by flash-photolysis time-resolved microwave conductivity (TRMC) and transient absorption spectroscopy (TAS). It was found that the dependence of photocarrier generation efficiency on excitation photon density differed from that of emission efficiency once amplified spontaneous emission (ASE) and resultant spectrally narrowed emission occur upon exposure to 355 nm. In contrast, the dependences of emission and photocarrier generation efficiencies were identical when ASE was not involved at a different excitation wavelength (193 nm). An approximated analytical solution of rate equation considering ASE or singlet-singlet annihilation was applied to the experiments, exhibiting good agreement. On the basis of TRMC, TAS, and extinction coefficient of radical cation assessed by pulse radiolysis, the minimum charge carrier mobility was estimated, without electrodes, to be 0.12 cm2 V-1 s-1. The dynamics of charge carrier and triplet excited state is discussed, accompanying with examination by time-dependent density functional theory. The present work would open the way to a deeper understanding of the fate of excited state in optically robust organic semiconducting crystals.

Saeki, Akinori; Seki, Shu; Shimizu, Yasuhiro; Yamao, Takeshi; Hotta, Shu

2010-04-01

254

Spontaneous coherent microwave emission and the sawtooth instability in a compact storage ring  

Microsoft Academic Search

Strong evidence for self-excited emission of coherent synchrotron radiation in the microwave spectral region was observed at the Synchrotron Ultraviolet Radiation Facility (SURF III) electron storage ring at the NIST. The microwave emission between 25 and 35 mm was dominated by intense bursts of radiation. The intensity enhancement during these bursts was on the order of 10 000 to 50

U. Arp; G. T. Fraser; A. R. Hight Walker; T. B. Lucatorto; K. K. Lehmann; K. Harkay; N. Sereno; K.-J. Kim

2001-01-01

255

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...

256

Imaging of Ultraweak Spontaneous Photon Emission from Human Body Displaying Diurnal Rhythm  

PubMed Central

The human body literally glimmers. The intensity of the light emitted by the body is 1000 times lower than the sensitivity of our naked eyes. Ultraweak photon emission is known as the energy released as light through the changes in energy metabolism. We successfully imaged the diurnal change of this ultraweak photon emission with an improved highly sensitive imaging system using cryogenic charge-coupled device (CCD) camera. We found that the human body directly and rhythmically emits light. The diurnal changes in photon emission might be linked to changes in energy metabolism.

Kobayashi, Masaki; Kikuchi, Daisuke; Okamura, Hitoshi

2009-01-01

257

Controllable frequency entanglement via auto-phase-matched spontaneous parametric down-conversion  

NASA Astrophysics Data System (ADS)

A method for generating entangled photons with controllable frequency correlation via spontaneous parametric down-conversion (SPDC) is presented. The method entails initiating counterpropagating SPDC in a single-mode nonlinear waveguide by pumping with a pulsed beam perpendicular to the waveguide. The method offers several advantages over other schemes, including the ability to generate frequency-correlated photon pairs regardless of the dispersion characteristics of the system.

Walton, Zachary D.; Booth, Mark C.; Sergienko, Alexander V.; Saleh, Bahaa E.; Teich, Malvin C.

2003-05-01

258

Postoperative vomiting following strabismus surgery in paediatric outpatients: spontaneous versus controlled ventilation  

Microsoft Academic Search

The study was designed to compare the frequency and severity of postoperative vomiting in paediatric out-patients receiving\\u000a controlled ventilation (IPPV) or breathing spontaneously (SV) during anaesthesia for strabismus repair. One hundred and twenty\\u000a unpremedicated children (ages 2-12 years) were studied in a randomized fashion. After intravenous induction of anaesthesia\\u000a and tracheal intubation, patients breathed halothane 1-1.5 per cent inspired and

Catherine Walsh; Charles E. Smith; Beverly Ryan rn; Robert C. Polomeno; Joan C. Bevan

1988-01-01

259

Method for controlling dust and spontaneous combustion in the drying, handling, transporting and storing of coal  

SciTech Connect

A method is described of controlling dust formation and spontaneous combustion in drying, handling, transporting, and storing of low rank coal selected from the group consisting of lignite, peat, and subbituminous coal containing about 20-50% water comprising: applying to the coal a dust inhibiting amount of an aqueous solution consisting essentially of gelatinized starch at a temperature of from about 60/sup 0/C. to about 200/sup 0/C. by spraying the solution over the coal.

Yan, T.Y.

1987-02-10

260

IDENTIFICATION, ASSESSMENT, AND CONTROL OF FUGITIVE PARTICULATE EMISSIONS  

EPA Science Inventory

The technical manual, designed to assist national, state, and local control agency personnel and industry personnel in evaluating fugitive emission control plans and in developing cost-effective control strategies, describes the identification, assessment, and control of fugitive...

261

Enhancement of Spontaneous Erbium Emission near the Photonic Band Edge of Distributed Bragg Reflectors Based on a-Si:H/a-SiO{sub x}:H  

SciTech Connect

Results obtained in an experimental study of spontaneous emission from erbium ions in a spectral range corresponding to the lower photonic band edge of distributed Bragg reflectors (1D photonic crystals) are presented. The photonic crystals were constituted of alternating quarter-wave a-Si:H and a-SiO{sub x}:H layers grown by PECVD. Erbium was introduced into the a-Si:H layers by magnetron sputtering of an erbium target in the course of structure growth. The change observed in the intensity of spontaneous emission is due to the nonmonotonic behavior of the density of optical modes near the photonic band edge.

Medvedev, A.V.; Feoktistov, N.A.; Pevtsov, A.B.; Golubev, V.G. [Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, 194021 (Russian Federation)

2005-11-15

262

Enhanced control of mercury emissions through modified speciation  

Microsoft Academic Search

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

C. D. Livengood; M. H. Mendelsohn

1997-01-01

263

Identifying and controlling WTE (waste-to-energy) stack emissions  

Microsoft Academic Search

This article focuses on stack emissions from large, mass burn WTE plants equipped with acid gas and high efficiency particulate controls. Several dozen mass burn plants are operating or in the planning, design, and construction stages in the US. The emission data in this article come from plants that began operation in the 1980s. Optimal furnace operation and emissions control

R. Li; P. W. Frillici; J. W. Wilson

1990-01-01

264

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...

265

Spontaneous emission rates of a single-impurity molecule in dependence on its orientation in biaxial host crystal  

NASA Astrophysics Data System (ADS)

The spontaneous emission rate (SER) of a single impurity molecule for the electric dipole transition has been found in the case where the birefringence of a host crystal is taken into account. SER depends on the orientation of the dipole moment with respect to the principal axes of the dielectric (permittivity) tensor of the host crystal and on the principal refiactive indices of the crystal. We use the model where the average electromagnetic field in the crystal is classical and effective electric field vectors at the site of the impurity molecule are found for the interstitial impurity which is located in the center of the crystal cell. The results of calculations for seven biaxial host crystals (anthracene, chrysene, diphenyl, fluorine, naphthalene, phenanthrene, terphenyl) are presented. It is shown that values of SER form in the space a three- axial ellipsoid. Differences in the values of SER for the electric dipole transition in the same host crystal are up to 34%.

Rebane, Inna

2005-08-01

266

Importance of dye host on absorption, propagation losses, and amplified spontaneous emission for dye-doped polymer thin films.  

PubMed

The absorption spectra of dye-doped polymer thin films made from a variety of five dyes and six matrices, either organic or organomineral, are analyzed to evaluate the residual absorption in the red wavelength tail and in particular at amplified spontaneous emission (ASE) wavelengths. An absorption cutoff wavelength is defined as the extrapolated wavelength at which the absorption losses are expected to become negligible compared to the structure losses. Such absorption-spectrum-extrapolated wavelengths are compared to the ASE wavelengths and found to correlate for most of the dye-matrix couples. The propagation losses of PM597-doped organic polymers are also measured and accordingly found to increase with the glass transition temperature of the host matrix. PMID:17068612

Goudket, Hélène; Nhung, Tran Hong; Ea-Kim, Buntha; Roger, Gisèle; Canva, Michael

2006-10-10

267

Importance of dye host on absorption, propagation losses, and amplified spontaneous emission for dye-doped polymer thin films  

NASA Astrophysics Data System (ADS)

The absorption spectra of dye-doped polymer thin films made from a variety of five dyes and six matrices, either organic or organomineral, are analyzed to evaluate the residual absorption in the red wavelength tail and in particular at amplified spontaneous emission (ASE) wavelengths. An absorption cutoff wavelength is defined as the extrapolated wavelength at which the absorption losses are expected to become negligible compared to the structure losses. Such absorption-spectrum-extrapolated wavelengths are compared to the ASE wavelengths and found to correlate for most of the dye-matrix couples. The propagation losses of PM597-doped organic polymers are also measured and accordingly found to increase with the glass transition temperature of the host matrix.

Goudket, Hélène; Nhung, Tran Hong; Ea-Kim, Buntha; Roger, Gisèle; Canva, Michael

2006-10-01

268

Biopolymer based system doped with nonlinear optical dye as a medium for amplified spontaneous emission and lasing  

NASA Astrophysics Data System (ADS)

In this paper, we present results of detailed studies on amplified spontaneous emission (ASE) and lasing achieved in a double-layer system consisted of a biopolymer based matrix loaded with 3-(1,1-dicyanoethenyl1)-1phenyl-4,5dihydro-1H-pyrazole organic nonlinear optical dye and photochromic polymer. The laser action was achieved via distributed feedback configuration with third order of Bragg scattering on surface relief grating generated in photochromic polymer. To excite the luminescence, we have used 6 ns pulses of Nd:YAG laser at 532 nm. The ASE and lasing thresholds were estimated to be 17 mJ/cm2 and 11 mJ/cm2, respectively.

Sznitko, Lech; Mysliwiec, Jaroslaw; Karpinski, Pawel; Palewska, Krystyna; Parafiniuk, Kacper; Bartkiewicz, Stanislaw; Rau, Ileana; Kajzar, Francois; Miniewicz, Andrzej

2011-07-01

269

Simple method for the temporal characterization of amplified spontaneous emission in femtosecond terawatt Ti:sapphire lasers.  

PubMed

We have analyzed the temporal characteristics of amplified spontaneous emission (ASE) in femtosecond terawatt Ti:sapphire lasers by using a simple method based on fast photodiodes. Instead of measuring ASE directly with fast photodiodes, we created a narrow gap in the spectrum of seed pulses and, after amplification, detected the pure ASE signal through the gap by using a fast photodiode covered with a bandpass filter with high transmission at the gap. Because the detected ASE signal was completely separated from amplified main pulses, preceding and even trailing ASEs could be characterized quantitatively in a single-shot measurement. We believe that our method is a good alternative or a complement to conventional methods for ASE measurements. PMID:17906710

Cha, Yong-Ho; Lee, Yong-Woo; Nam, Sung Mo; Han, Jae Min; Rhee, Yong Joo; Yoo, Byung Duk; Lee, Byoung Chul; Jeong, Young Uk

2007-10-01

270

A linear integral-equation-based computer code for self-amplified spontaneous emission calculations of free-electron lasers  

NASA Astrophysics Data System (ADS)

The linear integral-equation-based computer code ``Roger Oleg Nikolai'' (RON), which was recently developed at Argonne National Laboratory, was used to calculate the self-amplified spontaneous emission (SASE) performance of the free-electron laser (FEL) being built at Argonne. Signal growth calculations under different conditions were used to estimate tolerances of actual design parameters and to estimate optimal length of the break sections between undulator segments. Explicit calculation of the radiation field was added recently. The measured magnetic fields of five undulators were used to calculate the gain for the Argonne FEL. The result indicates that the real undulators for the Argonne FEL (the effect of magnetic field errors alone) will not significantly degrade the FEL performance. The capability to calculate the small-signal gain for an FEL-oscillator is also demonstrated.

Dejus, R. J.; Shevchenko, O. A.; Vinokurov, N. A.

2000-05-01

271

Spectral broadening effects of spontaneous emission and density of state on plasmonic enhancement in cermet waveguides.  

PubMed

Based on the full integration formula of Purcell factor (PF) deduced from Fermi's Golden Rule, the plasmonic enhancement in Au(1-?)S3N4(?) cermet waveguides is evaluated with the joint impact of finite emission linewidth and the broadening of PF spectrum. The calculation results indicate that the PF would be significantly degraded by the two broadening effects though the SPP resonance frequency can be tuned with different volume fractions (?) of Si3N4. It is also found that the critical emission linewidth is approximately linear to the PF spectrum linewidth. Thus in order to achieve strong plasmonic enhancement, both the emission and PF spectrum linewidths should be dramatically reduced. PMID:23388935

Chen, Keyong; Feng, Xue; Zhang, Chao; Cui, Kaiyu; Huang, Yidong

2013-01-14

272

Mercury emission control technologies: An EPRI synopsis  

SciTech Connect

The air toxics provisions under Title III of the 1990 Clean Air Act Amendments (CAAA) require the US Environmental Protection Agency (EPA) to conduct a study that focuses on electric utility emissions. Due to be completed by the end of 1995, this study is being conducted to determine whether the release of toxic materials, including mercury, present an unacceptable risk to public health. Of the 189 substances designated hazardous air pollutants (commonly called air toxics), mercury was also singled out for a separate report because of concerns that humans could be harmed by the consumption of fish that have accumulated methylmercury from their food sources. The Electric Power Research Institute (EPRI), the research and development arm of its member electric utilities, is conducting research on mercury in four areas: (1) determining the extent of mercury emissions from electric utility power plants, (2) understanding health effects, (3) modeling mercury dispersion transport, deposition and bioaccumulation, and (4) assessing mercury control strategies. While the focus of this paper is on the last area, a precis of the results obtained to date in the other three areas is presented first.

Change, R.; Offen, G.R.

1995-11-01

273

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

PubMed

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

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

2011-11-03

274

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

SciTech Connect

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.

Zeng Xiaodong; Xu Jingping; Yang Yaping [Key Laboratory of Advanced Micro-Structure Materials, Ministry of Education (China); Department of Physics, Tongji University, Shanghai 200092 (China)

2011-09-15

275

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

SciTech Connect

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.

Bergou, J.; Orszag, M.

1988-02-01

276

Amplified spontaneous emission light source near 640 nm in an organic–inorganic hybrid device based on a dye-filled hollow optical fiber  

Microsoft Academic Search

A new type of amplified spontaneous emission (ASE) source in the visible range is proposed and experimentally demonstrated using a novel dye-filled hollow optical fiber (HOF) with a ring core, where optical guiding is provided by silica fiber while the gain is obtained by organic dye to form an organic–inorganic hybrid active device. The pump and signal light intensity distributions

Seongwoo Yoo; Junki Kim; Kyunghwan Oh

2005-01-01

277

Spectrum of collective spontaneous emission beyond the rotating-wave approximation  

NASA Astrophysics Data System (ADS)

The spectrum of cooperative light emission from ensembles of multilevel atoms is studied in optical vector theory and without applying the rotating-wave approximation. The effects of counter-rotating terms are included using a unitary transformation method. The spectra are analyzed and interpreted in terms of the radiative eigenmodes of the atom ensemble. We further show how the qualitative features arise from the structure of the underlying two-particle dipole-dipole interaction induced by the the vacuum field. We predict that for a suitable modification of the ensemble properties, the sign of the cooperative Lamb shift can be reversed, while still maintaining strong superradiant emission. Finally, we discuss the effects of finite detection resolution and of averaging over many realizations of the random distribution of atoms for given ensemble parameters.

Li, Yong; Evers, Jörg; Feng, Wei; Zhu, Shi-Yao

2013-05-01

278

Spontaneous emission spectra and quantum light-matter interactions from a strongly coupled quantum dot metal-nanoparticle system  

NASA Astrophysics Data System (ADS)

We investigate the quantum optical properties of a quantum-dot dipole emitter coupled to a finite-size metal nanoparticle using a photon Green-function technique that rigorously quantizes the electromagnetic fields. We first obtain pronounced Purcell factors and photonic Lamb shifts for both a 7- and 20-nm-radius metal nanoparticle, without adopting a dipole approximation. We then consider a quantum-dot photon emitter positioned sufficiently near the metal nanoparticle so that the strong-coupling regime is possible. Accounting for nondipole interactions, quenching, and photon transport from the dot to the detector, we demonstrate that the strong-coupling regime should be observable in the far-field spontaneous emission spectrum, even at room temperature. The vacuum-induced emission spectra show that the usual vacuum Rabi doublet becomes a rich spectral triplet or quartet with two of the four peaks anticrossing, which survives in spite of significant nonradiative decays. We discuss the emitted light spectrum and the effects of quenching for two different dipole polarizations.

van Vlack, C.; Kristensen, Philip Trøst; Hughes, S.

2012-02-01

279

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

SciTech Connect

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.

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

2009-02-01

280

Ultraviolet spontaneous and stimulated emissions from ZnO microcrystallite thin films at room temperature  

Microsoft Academic Search

Room-temperature free excition absorption and luminescence are observed in ZnO thin films grown on sapphire substrates by the laser molecular beam epitaxy technique. At moderate optical pumping intensities, an excition-exciton collision induced stimulated emission peak is observed at 390 nm. The existence of this peak is related to the presence of closely packed hexagonally shaped microcrystallites in these films. Stimulated

P. Zu; Z. K. Tang; G. K. L. Wong; M. Kawasaki; A. Ohtomo; H. Koinuma; Y. Segawa

1997-01-01

281

Quantum theory of spontaneous emission and coherent effects in semiconductor microstructures  

Microsoft Academic Search

A fully quantum-mechanical theory for the interaction of light and electron–hole excitations in semiconductor quantum-well systems is developed. The resulting many-body hierarchy for the correlation functions is truncated using a dynamical decoupling scheme leading to coupled semiconductor luminescence and Bloch equations. For incoherent excitation conditions, the theory is used to describe nonlinear excitonic emission properties of single-quantum wells, optically coupled

M. Kira; F. Jahnke; W. Hoyer; S. W. Koch

1999-01-01

282

Non-Markovian theory of relativistic electric-dipole spontaneous emission of hydrogen-like atoms  

Microsoft Academic Search

The non-Markovian corrections to electric-dipole emission of hydrogen-like atoms of large atomic number Z are studied by multipole photon field formulation. The correlation functions are derived by the corresponding spectra, which show how the delta-function type correlation is approached. The decay of upper-level population is calculated by the relevant integro-differential equation. The numerical results show that the relativistic and finite

Chang-qi Cao; Xiao-wei Fu; Hui Cao

2005-01-01

283

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

NASA Astrophysics Data System (ADS)

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.

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

2007-06-01

284

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

SciTech Connect

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.

Qamar, Shahid [Centre for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Xiong Han [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Zubairy, M. Suhail [Centre for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Texas A and M University at Qatar, Education City, P.O. Box 23874, Doha (Qatar)

2007-06-15

285

Controlling nitrous oxide emissions from grassland livestock production systems  

Microsoft Academic Search

There is growing awareness that grassland livestock production systems are major sources of nitrous oxide (N2O). Controlling these emissions requires a thorough understanding of all sources and controlling factors at the farm level. This paper examines the various controlling factors and proposes farm management measures to decrease N2O emissions from intensively managed grassland livestock farming systems. Two types of regulating

O. Oenema; G. Gebauer; M. Rodriguez; A. Sapek; S. C. Jarvis; W. J. Corré; S. Yamulki

1998-01-01

286

Emissions Control in the Grain and Feed Industry: Volume II. Emission Inventory.  

National Technical Information Service (NTIS)

Volume I of this study reports on Emissions Control in the Grain and Feed Industry and contains much or all available information on emission sources within this industry. The objective in Volume II is to evaluate this information, prepare an emission inv...

L. J. Shannon P. G. Gorman

1974-01-01

287

COMPUTER-CONTROLLED, REAL-TIME AUTOMOBILE EMISSIONS MONITORING SYSTEM  

EPA Science Inventory

A minicomputer controlled automotive emissions sampling and analysis system (the Real-Time System) was developed to determine vehicular modal emissions over various test cycles. This data acquisition system can sample real-time emissions at a rate of 10 samples/s. A buffer utiliz...

288

Control of gas emissions in underground coal mines  

Microsoft Academic Search

A high level of knowledge is now available in the extremely relevant field of underground gas emissions from coal mines. However, there are still tasks seeking improved solutions, such as prediction of gas emissions, choice of the most suitable panel design, extension of predrainage systems, further optimization of postdrainage systems, options for the control of gas emissions during retreat mining

Klaus Noack

1998-01-01

289

Effect of colorpuncture on spontaneous photon emission in a subject suffering from multiple sclerosis.  

PubMed

Spontaneous photon signals from four sites of a human subject suffering from multiple sclerosis were detected in 3600 bins of 50 milliseconds by a photo multiplier sensitive in 160-630 nm, before and after a session of colorpuncture treatment. Measurements were made in 22 sessions over a period of 9 months. Each signal was analyzed to determine if it was a quantum signal in a squeezed state. The analysis first generates 10 signals of bin sizes (50 to 500 milliseconds at 50 millisecond intervals) by merging the counts at contiguous bins of the observed signal and then estimates three squeezed state parameters (r, theta and phi) in these ten signals and nine other combinations of signals. All estimations yield r=2.72.10(-10), theta = 101.91 degrees and phi = 69.53 degrees for TolX=10(-8) in every signal of a healthy subject. These are normal values of the parameters. Other values of parameters in a signal of any estimation indicate some ailment. The deviation from the squeezed state description of a signal is quantified by a new property, "coherency index", which appears to be a good indicator of health. A session of colorpuncture treatment changed coherency indices of signals from different sides and provided relief to the subject suffering from multiple sclerosis. The changes in coherency indices and relief were temporary. Changes in coherency indices lasting for longer periods occurred after many sessions of treatment. PMID:20633463

Bajpai, R P; Drexel, M

2008-12-01

290

Theory of spontaneous emission of quantum dots in the linear regime.  

PubMed

We develop a fully quantum-mechanical theory for the interaction of light and electron-hole excitations in semiconductor quantum dots. Our theoretical analysis results in an expression for the photoluminescence intensity of quantum dots in the linear regime. Taking into account the single-particle Hamiltonian, the free-photon Hamiltonian, the electron-hole interaction Hamiltonian, and the interaction of carriers with light, and applying the Heisenberg equation of motion to the photon number expectation values, to the carrier distribution functions and to the correlation term between the photon generation (destruction) and electron-hole pair, we obtain a set of luminescence equations. Under quasi-equilibrium conditions, these equations become a closed-set of equations. We solve them analytically, in the linear regime, and we find an approximate solution of the incoherent photoluminescence intensity. The validity of the theoretical analysis is tested by investigating the emission spectra in the high-temperature regime, interpreting the experimental findings for the emission spectra of a lens-shaped In(0.5)Ga(0.5)As self-assembled quantum dot. Our theoretical predictions for the interlevel spacing as well as for the dephasing time caused by electron-longitudinal optical phonon interactions are in good agreement with the experimental results. PMID:22049100

Zora, A; Simserides, C; Triberis, G P

2007-09-11

291

Pilot randomized controlled trial of Reciprocal Imitation Training for teaching elicited and spontaneous imitation to children with autism.  

PubMed

Children with autism exhibit significant deficits in imitation skills. Reciprocal Imitation Training (RIT), a naturalistic imitation intervention, was developed to teach young children with autism to imitate during play. This study used a randomized controlled trial to evaluate the efficacy of RIT on elicited and spontaneous imitation skills in 21 young children with autism. Results found that children in the treatment group made significantly more gains in elicited and spontaneous imitation, replicating previous single-subject design studies. Number of spontaneous play acts at pre-treatment was related to improvements in imitation during the intervention, suggesting that children with a greater play repertoire make greater gains during RIT. PMID:20155309

Ingersoll, Brooke

2010-09-01

292

Gas turbine combustion and emission control  

Microsoft Academic Search

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

B. Schetter

1993-01-01

293

Alternative Control Techniques Document: NOx Emissions from Cement Manufacturing.  

National Technical Information Service (NTIS)

This alternative control technique (ACT) document provides technical information for use by State and local agencies to develop and implement regulatory programs to control NOx emissions from cement kilns. Chapter 2 presents a summary of the findings of t...

W. J. Neuffer

1994-01-01

294

Evaluation of Emission Control Options at Leeds Architectural Products.  

National Technical Information Service (NTIS)

The U.S. Environmental Protection Agency's Control Technology Center evaluated feasible alternatives to control emissions of volatile organic compounds (VOC) from a specialty aluminum coating facility in CT. The facility desired to increase its use of hig...

J. N. Bolstad

1989-01-01

295

Landfill operation for carbon sequestration and maximum methane emission control.  

National Technical Information Service (NTIS)

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 generat...

D. Augenstein R. Yazdani R. Moore M. Byars J. Kieffer M. Barlaz R. Mehta

2000-01-01

296

Evaluation of Emission Control Devices at Waferboard Plants.  

National Technical Information Service (NTIS)

The document discusses emissions from wood chip dryers and the candidate control devices that should be considered in a best available control technology analysis. Specifically, the document characterizes wood chip dryer effluents and presents a general d...

C. C. Vaught

1989-01-01

297

APTI Course 415: Control of gaseous emissions. Instructor's guide  

Microsoft Academic Search

The Instructor's Guide is to be used for the Air Pollution Training Institute Course 415, Control of Gaseous Emissions. The publication contains complete information for conducting a 4-day course in gaseous emission control. The guide contains course goals and objectives, preparation instructions, lesson plans, exams and exam keys, and solution to the problem sets. The lesson plans include keys to

J. Joseph; D. Beachler; J. Jahnke; M. Leslie; J. Henry

1981-01-01

298

Controlling vehicular emissions in Beijing during the last decade  

Microsoft Academic Search

The vehicle population of Beijing is sharply increasing at an average annual rate of 14.5%, causing severe transportation and environmental problems. The Beijing municipal government and the public have worked hard to control vehicular emissions since 1995. Strategies and measures have been introduced to regulate land use and traffic planning, emission control of in-use vehicles and new vehicles, fuel quality

Jiming Hao; Jingnan Hu; Lixin Fu

2006-01-01

299

Safety hazards associated with air-emission controls  

Microsoft Academic Search

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

Henry Ozog; William J. Erny

2000-01-01

300

Systems approach to dust emission control at coal piles  

Microsoft Academic Search

At Detroit Edison's Superior Midwest Energy Terminal, dust emission control has been an ongoing concern. Testing and evaluation of different systems have been carried out since the terminal was built, and emission controls have been expanded. The latest addition is a coal pile spray system.

Mahr

1983-01-01

301

Spontaneous fission  

SciTech Connect

The spontaneous fission (SF) of the heaviest actinides and the transactinides is of particular interest because of the dramatic changes in properties observed in the region of the heavy fermion isotopes and for still heavier elements. The existing experimental information on SF properties including half-life systematics, fragment kinetic-energy and mass-yield distributions, prompt neutron emission, and gamma emission will be reviewed. Possibility for extending studies of SF properties to other regions are considered and the potential for obtaining additional information about low-energy fission properties is discussed.

Hoffman, D.C. [Lawrence Berkeley Lab., CA (United States)

1993-09-01

302

Spontaneous fission  

NASA Astrophysics Data System (ADS)

The spontaneous fission (SF) of the heaviest actinides and the transactinides is of particular interest, because of the dramatic changes in properties observed in the region of the heavy fermium isotopes and for still heavier elements. The existing experimental information on SF properties, including half-life systematics, fragment kinetic energy and mass yield distributions, prompt neutron emission and gamma emission, will be reviewed. Possibilities for extending studies of SF properties to other regions are considered, and the potential for obtaining additional information about low-energy fission properties is discussed.

Hoffman, Darleane C.

1994-10-01

303

Approximate Entropy Values Demonstrate Impaired Neuromotor Control of Spontaneous Leg Activity in Infants with Myelomeningocele  

PubMed Central

Purpose One obstacle to providing early intervention to infants with myelomeningocele (MMC) is the challenge of quantifying impaired neuromotor control of movements early in life. Methods We used the nonlinear analysis tool Approximate Entropy (ApEn) to analyze periodicity and complexity of supine spontaneous lower extremity movements of infants with MMC and typical development (TD) at 1, 3, 6 and 9 months of age. Results Movements of infants with MMC were more regular and repeatable (lower ApEn values) than movements of infants with TD indicating less adaptive and flexible movement patterns. For both groups ApEn values decreased with age, and the movements of infants with MMC were less complex than movements of infants with TD. Further, for infants with MMC, lesion level and age of walking onset correlated negatively with ApEn values. Conclusions Our study begins to demonstrate the feasibility of ApEn to identify impaired neuromotor control in infants with MMC.

Smith, Beth A.; Teulier, Caroline; Sansom, Jennifer; Stergiou, Nicholas; Ulrich, Beverly D.

2012-01-01

304

X-ray nonlinear optical processes using a self-amplified spontaneous emission free-electron laser  

SciTech Connect

In contrast to the long-wavelength regime, x-ray nonlinear optical processes 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 self-amplified spontaneous emission free-electron laser as fully chaotic, a quantum-mechanical analysis of inner-shell two-photon absorption is performed. It is demonstrated that double-core-hole formation via x-ray two-photon absorption is enhanced by chaotic photon statistics. Numerical calculations using rate equations illustrate the impact of field chaoticity on x-ray nonlinear ionization of helium and neon for photon energies near 1 keV. In the case of neon, processes are discussed that involve up to seven photons. Assuming an x-ray coherence time of 2.6 fs, double-core-hole formation in neon is found to be statistically enhanced by about 30% at an intensity of 10{sup 16} W/cm{sup 2}.

Rohringer, Nina; Santra, Robin [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2007-09-15

305

Cold-start hydrocarbon emissions control  

SciTech Connect

This article describes an effective, energy-efficient strategy for dealing with this problem using HC traps and heat-exchange related catalyst beds that have been successfully tested. The worldwide regulatory climate for continued and dramatic reductions in vehicle exhaust emissions will continue unabated for some time. The best known of these mandates includes California Air Resources Board`s Low Emission Vehicle (CARB LEV) program, the Ozone Transport Commission`s recent petition to the EPA for partial adoption of CARB`s LEV program, and the European Economic Community`s proposed staged multi-tier approach to reduce auto exhaust pollution. Since up to 70% of hydrocarbon tailpipe emissions occur during the cold-start portion of the Federal Test Procedure (FTP), significant reductions in total FTP HC emissions must include a cold-start HC abatement strategy.

NONE

1995-10-01

306

AIR TOXICS EMISSIONS CHARACTERIZATION, CONTROLS & PREVENTION  

EPA Science Inventory

The goals of this research are to develop improved techniques to characterize hazardous air pollutant emissions from outdoor and indoor sources; use thee techniques to better understand the relative contribution of specific sources to actual human exposure, and identify innovativ...

307

CO emissions in China: Uncertainties and implications of improved energy efficiency and emission control  

NASA Astrophysics Data System (ADS)

A bottom-up methodology and an improved database of emission factors combining the latest domestic field measurements are developed to estimate the emissions of anthropogenic CO from China at national and provincial levels. The CO emission factors for major economic sectors declined to varying degrees from 2005 to 2009, attributed to improved energy efficiency and/or emission control regulations. Total national CO emissions are estimated at 173 Tg for 2005 and have been relatively stable for subsequent years, despite fast growth of energy consumption and industrial production. While industry and transportation sources dominated CO emissions in developed eastern and north-central China, residential combustion played a much greater role in the less developed western provinces. The uncertainties of national Chinese CO emissions are quantified using Monte Carlo simulation at -20% to +45% (95% confidence interval). Due to poor understanding of emission factors and activity levels for combustion of solid fuels, the largest uncertainties are found for emissions from the residential sector. The trends of bottom-up emissions compare reasonably to satellite observation of CO columns and to ground observations of CO2-CO correlation slopes. The increase in the ratio for emissions of CO2 relative to CO suggests that China has successfully improved combustion efficiencies across its economy in recent years, consistent with national policies to improve energy efficiency and to control criteria air pollutants.

Zhao, Yu; Nielsen, Chris P.; McElroy, Michael B.; Zhang, Lin; Zhang, Jie

2012-03-01

308

Assessment and control of chrysotile asbestos emissions from unpaved roads  

NASA Astrophysics Data System (ADS)

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.

Serra, R. K.; Connor, M. A., Jr.

1981-05-01

309

Controls over hydrocarbon emissions from boreal forest conifers  

SciTech Connect

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.

Lerdau, M.; Litvak, M.; Monson, R. [State Univ. of New York, Stony Brook, NY (United States)]|[Univ. of Colorado, Boulder, CO (United States)

1995-06-01

310

CLASSICAL AREAS OF PHENOMENOLOGY: Modification of spontaneous emission rate of micrometer-sized light sources using hollow-core photonic crystal fibers  

NASA Astrophysics Data System (ADS)

We investigate numerically and experimentally the modification of the spontaneous emission rate for micrometer-sized light sources embedded in a hollow-core photonic crystal fiber (HCPCF). The diameter of the light source is deliberately chosen such that they could be easily introduced into the central hole of the hollow-core photonic crystal fiber by capillary force. The photoluminescence from the microparticles is measured by using an inverted microscope in combination with a spectrometer. The modification of the spontaneous emission rate is observed in a wavelength region where there is no band gap. The experimental observations are consistent with the simulation results obtained by the plane wave expansion and finite-difference time-domain techniques.

Lu, Jiao-Hua; Meng, Zi-Ming; Liu, Hai-Ying; Feng, Tian-Hua; Dai, Qiao-Feng; Wu, Li-Jun; Guo, Qi; Hu, Wei; Lan, Sheng

2009-10-01

311

Utilization of CTR to measure the evolution of electron-beam microbunching in a self-amplified spontaneous emission (SASE) free-electron laser (FEL)  

Microsoft Academic Search

We report on the first measurements of the z-dependent evolution of electron-beam microbunching as revealed through coherent transition radiation (CTR) measurements in a visible self-amplified spontaneous emission free-electron laser experiment. The increase in microbunching was detected by tracking the growth of the visible CTR signals as generated from insertable metal mirrors\\/foils after each of the last three undulators. The same

A. H Lumpkin; B. X. Yang; W. J Berg; Y. C Chae; J. W Lewellen; N. S Sereno; R. J Dejus; C. Benson; E. Moog

2002-01-01

312

Experimental characterization of the saturating, near infrared, self-amplified spontaneous emission free electron laser: Analysis of radiation properties and electron beam dynamics  

Microsoft Academic Search

In this work, the main results of the VISA experiment (Visible to Infrared SASE Amplifier) are presented and analyzed. The purpose of the experiment was to build a state-of-the-art single pass self-amplified spontaneous emission (SASE) free electron laser (FEL) based on a high brightness electron beam, and characterize its operation, including saturation, in the near infrared spectral region. This experiment

Alex Murokh

2002-01-01

313

Effect of a modified reservoir on the nature of interference in the spontaneous emission of a driven four-level atom  

Microsoft Academic Search

The effect of a modified reservoir on the nature of the quantum interference in the spontaneous emission of a driven double V-type four-level atom has been investigated. In the model used, the double V-type transitions of a driven atom interact respectively with a free vacuum reservoir and a modified reservoir, leading to the two possible types of quantum interference. The

S. Roshan Entezar; H. Vahed; H. Tajalli

2007-01-01

314

Three-dimensional simulations of the generation of one Angstrom radiation by a self-amplified spontaneous emission free-electron laser  

SciTech Connect

Three-dimensional numerical simulations of the generation of one Angstrom x-rays by a free-electron laser operating in the self-amplified spontaneous emission mode have been performed. Using model electron beam and wiggler parameters, we have investigated the length of wiggler needed to just avoid bandwidth broadening effects associated with gain saturation, and we have also obtained requirements for wiggler field errors to avoid significant loss of performance. 14 refs., 5 figs., 1 tab.

Goldstein, J.C.; Elliott, C.J.; Schmitt, M.J.

1990-01-01

315

Role of amplified spontaneous emission in optical free-space communication links with optical amplification: impact on isolation and data transmission and utilization for pointing, acquisition, and  

Microsoft Academic Search

We investigate the role of amplified spontaneous emission (ASE) produced by an optical booster amplifier at the transmitter of free-space optical communication links. In a communication terminal with a single telescope for both transmission and reception, this ASE power has to be taken into account in connection with transmit-to-receive channel isolation, especially since it partly occupies the same state of

Peter J. Winzer; Andras Kalmar; Walter R. Leeb

1999-01-01

316

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

SciTech Connect

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.

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

1988-04-15

317

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

PubMed

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

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

2012-12-12

318

Spontaneous emission from radiative chiral nematic liquid crystals at the photonic band-gap edge: an investigation into the role of the density of photon states near resonance.  

PubMed

In this article, we investigate the spontaneous emission properties of radiating molecules embedded in a chiral nematic liquid crystal, under the assumption that the electronic transition frequency is close to the photonic edge mode of the structure, i.e., at resonance. We take into account the transition broadening and the decay of electromagnetic field modes supported by the so-called "mirrorless"cavity. We employ the Jaynes-Cummings Hamiltonian to describe the electron interaction with the electromagnetic field, focusing on the mode with the diffracting polarization in the chiral nematic layer. As known in these structures, the density of photon states, calculated via the Wigner method, has distinct peaks on either side of the photonic band gap, which manifests itself as a considerable modification of the emission spectrum. We demonstrate that, near resonance, there are notable differences between the behavior of the density of states and the spontaneous emission profile of these structures. In addition, we examine in some detail the case of the logarithmic peak exhibited in the density of states in two-dimensional photonic structures and obtain analytic relations for the Lamb shift and the broadening of the atomic transition in the emission spectrum. The dynamical behavior of the atom-field system is described by a system of two first-order differential equations, solved using the Green's-function method and the Fourier transform. The emission spectra are then calculated and compared with experimental data. PMID:23848702

Mavrogordatos, Th K; Morris, S M; Wood, S M; Coles, H J; Wilkinson, T D

2013-06-17

319

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...

320

Sulfur oxide adsorbents and emissions control  

DOEpatents

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.

Li, Liyu (Richland, WA); King, David L. (Richland, WA)

2006-12-26

321

Control of benzene emissions from light-duty motor vehicles. Final report  

Microsoft Academic Search

Several strategies to reduce the total amount of exhaust and evaporative benzene emissions from light-duty gasoline-fueled vehicles have been investigated. A literature search was performed to determine automotive benzene emission levels and technologies for benzene emission control. Laboratory vehicle emission tests were performed to demonstrate benzene control technologies. Exhaust benzene emission control was addressed by reducing total hydrocarbon emissions (including

Heimrich

1991-01-01

322

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

SciTech Connect

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.

Lu, N.; Zhu, S. (Center for Advanced Studies and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 (US))

1989-11-15

323

Pump-Controlled Directional Light Emission from Random Lasers  

NASA Astrophysics Data System (ADS)

The angular emission pattern of a random laser is typically very irregular and difficult to tune. Here we show by detailed numerical calculations that one can overcome the lack of control over this emission pattern by actively shaping the spatial pump distribution. We demonstrate, in particular, how to obtain customized pump profiles to achieve highly directional emission. Going beyond the regime of strongly scattering media where localized modes with a given directionality can simply be selected by the pump, we present an optimization-based approach which shapes extended lasing modes in the weakly scattering regime according to any predetermined emission pattern.

Hisch, Thomas; Liertzer, Matthias; Pogany, Dionyz; Mintert, Florian; Rotter, Stefan

2013-07-01

324

Physical Coal Cleaning for Utility Boiler SO2 Emission Control.  

National Technical Information Service (NTIS)

The report examines physical coal cleaning as a control technique for sulfur oxides emissions. It includes an analysis of the availability of low-sulfur coal and of coal cleanable to compliance levels for alternate New Source Performance Standards (NSPS)....

E. H. Hall L. Hoffman J. Hoffman R. A. Schilling

1978-01-01

325

Formaldehyde Emission Control Technology for Methanol-Fueled Vehicles.  

National Technical Information Service (NTIS)

This program involved screening and evaluation of catalyst systems from manufacturers throughout the world for control for formaldehyde emissions from methanol-fueled vehicles. Initially, catalyst samples were screened using a vehicle operating on M90. Th...

M. S. Newkirk

1994-01-01

326

Self-organized global control of carbon emissions  

NASA Astrophysics Data System (ADS)

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.

Zhao, Zhenyuan; Fenn, Daniel J.; Hui, Pak Ming; Johnson, Neil F.

2010-09-01

327

Emission control cost-effectiveness of alternative-fuel vehicles  

SciTech Connect

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.

Wang, Q. [Argonne National Lab., IL (United States); Sperling, D.; Olmstead, J. [California Univ., Davis, CA (United States). Inst. of Transportation Studies

1993-06-14

328

Control emissions from aboveground storage tanks  

Microsoft Academic Search

Volatile organic compounds (VOCs) are emitted as vapors escape from aboveground organic liquid storage tanks. The US Environmental Protection Agency (EPA) estimates that in the petroleum industry along, in the absence of additional regulation, storage tank VOC emissions would reach 231,000 t\\/yr from the gasoline distribution industry and 122,000 t\\/yr from the petroleum refining industry by 1998. Proposed storage tank

C. Brown; P. Dixon

1996-01-01

329

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

PubMed Central

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.

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

2013-01-01

330

A prospective controlled trial comparing spontaneous closure and Epifilm(®) patching in traumatic tympanic membrane perforations.  

PubMed

The objective was to compare the outcomes of spontaneous closure and hyaluronic acid (HA) ester patching (Epifilm(®)) in subjects with traumatic tympanic membrane (TM) perforation. This was a prospective, controlled study performed at a tertiary teaching and research hospital. During 6-month period, subjects were divided into spontaneous closure (group A) and HA ester patch-Epifilm(®) (group B) group. Demographic data, presenting symptoms, closure rate, closure time and audiometric data were evaluated and compared between groups. In total, 155 subjects were evaluated. Group A consisted of 62.6 % (n = 97) of the subjects, whereas group B consisted of 37.4 % (n = 58) of the subjects. Group B had significantly shorter closure times when compared with group A (6.61 ± 4.59 vs. 10.60 ± 5.23 weeks, p = 0.001). When the closure time was evaluated according to perforation size both grade 1 and 2 perforations have significantly shorter closure times when compared with group A (6.33 ± 4.54 vs. 10.80 ± 5.69 weeks, for grade 1 and 6.650 ± 2.07 vs. 10.30 ± 4.32 weeks for grade 2 perforations). Closure rates were not significant between groups (85.6 % for group A and 94.8 % for group B). When the closure rate was evaluated according to perforation size no significant difference exists for grade 1, 2 and 3 perforations between groups. Both air conduction and air-bone gap were significantly improved in both groups. HA ester patch (Epifilm(®)) is a non-toxic material that can be used in traumatic tympanic membrane perforations. In this study, use of HA ester patching was resulted with earlier closure time but not resulted with higher closure rates. PMID:23292038

Sayin, Ibrahim; Kaya, Kamil Hakan; Ekizo?lu, O?uzhan; Erdim, Ibrahim; Kayhan, Fatma Tülin

2013-01-05

331

Correlation of angular light profiles of light-emitting diodes to spatial spontaneous emissions from photonic crystals  

NASA Astrophysics Data System (ADS)

Typically, photonic crystal light-emitting diodes employ shallow nanostructures which only higher-order optical modes can be interacted with. Here, both the shallow photonic crystals and nanohole arrays (etched through active layers) are fabricated, which serve to diffract, respectively, higher and lower optical modes in the active layer. Our results indicate that the photon lifetime can be controlled by adjusting the geometry of shallow nanostructures and nanohole arrays. The angular emission profiles are thus determined by the dominance of higher- and lower-order mode quality factors in the band structure.

Yin, Yu-Feng; Lin, Yen-Chen; Liu, Yi-Chen; Shen, Yi-Chun; Chiang, Hai-Pang; Huang, JianJang

2013-10-01

332

40 CFR 63.325 - Determination of equivalent emission control technology.  

Code of Federal Regulations, 2013 CFR

...Determination of equivalent emission control technology. 63.325 Section 63.325 Protection...Determination of equivalent emission control technology. (a) Any person requesting...illustrating the emission control technology, its operation and integration...

2013-07-01

333

Control of VOC emissions from nonferrous-metal rolling processes  

SciTech Connect

The document was developed in response to increasing inquiries into the environmental impacts of nonferrous metal rolling processes that use oil as a lubricant and coolant in rolling operations. VOC emissions result from evaporative fugitive losses caused by heat generated in the rolling processes. The focus of the document is VOC emission control techniques used by copper and aluminum rolling mills. A control cost analysis is also provided for each of the control techniques addressed. The control techniques are: carbon adsorption, absorption, incineration, and lubricant substitution.

Not Available

1992-06-01

334

Effect of spontaneous breathing on ventilator-induced lung injury in mechanically ventilated healthy rabbits: a randomized, controlled, experimental study  

PubMed Central

Introduction Ventilator-induced lung injury (VILI), one of the most serious complications of mechanical ventilation (MV), can impact patients' clinical prognoses. Compared to control ventilation, preserving spontaneous breathing can improve many physiological features in ventilated patients, such as gas distribution, cardiac performance, and ventilation-perfusion matching. However, the effect of spontaneous breathing on VILI is unknown. The goal of this study was to compare the effects of spontaneous breathing and control ventilation on lung injury in mechanically-ventilated healthy rabbits. Methods Sixteen healthy New Zealand white rabbits were randomly placed into a spontaneous breathing group (SB Group) and a control ventilation group (CV Group). Both groups were ventilated for eight hours using biphasic positive airway pressure (BIPAP) with similar ventilator parameters: inspiration pressure (PI) resulting in a tidal volume (VT) of 10 to 15 ml/kg, inspiratory-to-expiratory ratio of 1:1, positive end-expiration pressure (PEEP) of 2 cmH2O, and FiO2 of 0.5. Inflammatory markers in blood serum, lung homogenates and bronchoalveolar lavage fluid (BALF), total protein levels in BALF, mRNA expressions of selected cytokines in lung tissue, and lung injury histopathology scores were determined. Results Animals remained hemodynamically stable throughout the entire experiment. After eight hours of MV, compared to the CV Group, the SB Group had lower PaCO2 values and ratios of dead space to tidal volume, and higher lung compliance. The levels of cytokines in blood serum and BALF in both groups were similar, but spontaneous breathing led to significantly lower cytokine mRNA expressions in lung tissues and lower lung injury histological scores. Conclusions Preserving spontaneous breathing can not only improve ventilatory function, but can also attenuate selected markers of VILI in the mechanically-ventilated healthy lung.

2011-01-01

335

Programmable smart electron emission controller for hot filament  

NASA Astrophysics Data System (ADS)

In electron ionization source, electrons are produced through thermionic emission by heating a wire filament, accelerating the electrons by high voltage, and ionizing the analyzed molecules. In such a system, one important parameter is the filament emission current that determines the ionization rate; therefore, one needs to regulate this current. On the one hand, fast responses control is needed to keep the emission current constant, but on the other hand, we need to protect the filament from damage that occurs by large filaments current transients and overheating. To control our filament current and emission current, we developed a digital circuit based on a digital signal processing controller that has several modes of operation. We used a smart algorithm that has a fast response to a small signal and a slow response to a large signal. In addition, we have several protective measures that prevent the current from reaching unsafe values.

Flaxer, Eli

2011-02-01

336

Programmable smart electron emission controller for hot filament.  

PubMed

In electron ionization source, electrons are produced through thermionic emission by heating a wire filament, accelerating the electrons by high voltage, and ionizing the analyzed molecules. In such a system, one important parameter is the filament emission current that determines the ionization rate; therefore, one needs to regulate this current. On the one hand, fast responses control is needed to keep the emission current constant, but on the other hand, we need to protect the filament from damage that occurs by large filaments current transients and overheating. To control our filament current and emission current, we developed a digital circuit based on a digital signal processing controller that has several modes of operation. We used a smart algorithm that has a fast response to a small signal and a slow response to a large signal. In addition, we have several protective measures that prevent the current from reaching unsafe values. PMID:21361637

Flaxer, Eli

2011-02-01

337

Diesel particulate emission control without engine modifications  

SciTech Connect

This paper describes an ashless, fuel supplement which was found to typically reduce diesel particulate emissions by over 30% while significantly improving fuel economy and power output without any modifications to existing diesel engines or fuels. The treating cost is an order of magnitude less than the estimated cost of reducing aromatic content at the refinery to achieve particulate reductions. The particulate reduction is virtually all from the carbon (soot) fraction. The reduced soot formation translates into less abrasives and less soot-loading stress on the engine oil. Diesel tests conducted are also discussed.

Filowitz, M.S.; Vataru, M.

1989-01-01

338

Changes in children's nature-based experiences near home: from spontaneous play to adult-controlled, planned and organised activities  

Microsoft Academic Search

A qualitative case study from Brumunddalen, Norway, indicates that children's use of nature areas near their homes have changed substantially from being spontaneous and self-initiated to being part of planned, organised and adult-controlled activities. This study explores the association between changes in outdoor play and wider patterns of change in childhood today, as increasing amounts of play time is spent

Margrete Skår; Erling Krogh

2009-01-01

339

Brief Report: Pilot Randomized Controlled Trial of Reciprocal Imitation Training for Teaching Elicited and Spontaneous Imitation to Children with Autism  

ERIC Educational Resources Information Center

Children with autism exhibit significant deficits in imitation skills. Reciprocal Imitation Training (RIT), a naturalistic imitation intervention, was developed to teach young children with autism to imitate during play. This study used a randomized controlled trial to evaluate the efficacy of RIT on elicited and spontaneous imitation skills in 21…

Ingersoll, Brooke

2010-01-01

340

Association of TNF-? gene with spontaneous deep intracerebral hemorrhage in the Taiwan population: a case control study  

Microsoft Academic Search

BACKGROUND: Genetic factors may play a role in susceptibility to spontaneous deep intracerebral hemorrhage (SDICH). Previous studies have shown that TNF-? gene variation was associated with risks of subarachnoid hemorrhage in multiple ethnicities. The present case-control study tested the hypothesis that genetic variations of the TNF-? gene may affect the risk of Taiwanese SDICH. We examined the association of SDICH

Yi-Chun Chen; Fen-Ju Hu; Phoebe Chen; Yih-Ru Wu; Hsiu-Chuan Wu; Sien-Tsong Chen; Guey-Jen Lee-Chen; Chiung-Mei Chen

2010-01-01

341

Brief Report: Pilot Randomized Controlled Trial of Reciprocal Imitation Training for Teaching Elicited and Spontaneous Imitation to Children with Autism  

ERIC Educational Resources Information Center

|Children with autism exhibit significant deficits in imitation skills. Reciprocal Imitation Training (RIT), a naturalistic imitation intervention, was developed to teach young children with autism to imitate during play. This study used a randomized controlled trial to evaluate the efficacy of RIT on elicited and spontaneous imitation skills in…

Ingersoll, Brooke

2010-01-01

342

Ongoing Spontaneous Activity Controls Access to Consciousness: A Neuronal Model for Inattentional Blindness  

Microsoft Academic Search

Even in the absence of sensory inputs, cortical and thalamic neurons can show structured patterns of ongoing spontaneous activity, whose origins and functional significance are not well understood. We use computer simulations to explore the conditions under which spontaneous activity emerges from a simplified model of multiple interconnected thalamocortical columns linked by long-range, top-down excitatory axons, and to examine its

Stanislas Dehaene; Jean-Pierre Changeux

2005-01-01

343

Pollution control practices - hydrocarbon emission control in petroleum refineries  

SciTech Connect

This paper describes several years of experience with refinery fugitive emission rules and analyzes it in terms of recommendations for practice. It is shown that the data from the valve IandM program show a net economic return due to reduced stock losses when the Radian emission factors are used. Using lower emission factors or increasing the inspection frequency would adversely affect the cost effectiveness. The IandM program for pumps and compressors is a relatively cost-effective program from a regulatory agency's viewpoint. It is an expensive program to operate, but the cost effectiveness is as good as most other hydrocarbon reduction strategies currently under consideration for petroleum refineries. Estimating fugitive emissions is a critical part of obtaining construction permits for most new projects. Current IandM programs provide valuable data which helps to expedite the permitting process. 3 refs.

Freeberg, C.R.; Aarni, C.W.

1982-06-01

344

Determination of auto-PEEP during spontaneous and controlled ventilation by monitoring changes in end-expiratory thoracic gas volume.  

PubMed

Auto-PEEP, or PEEPi, occurs when alveolar pressure fails to decrease to zero at the end of exhalation. While PEEPi can be measured in paralyzed or apneic patients by occlusion of the ventilator expiratory valve at end-exhalation (PEEPi-OC), this may not be possible in patients with spontaneous respiratory efforts. When adjusting the ventilator PEEP valve, FRC increases only after PEEPi has been exceeded. In both mechanically ventilated and spontaneously breathing patients, changes in FRC are mirrored by changes in end-expiratory TGV as measured with RIP set in the DC mode. We compared PEEPi as measured by RIP to PEEPi-OC in 20 patients receiving mechanical ventilator support. Noninvasive measurement of changes in end-expiratory TGV by RIP is a convenient alternative method to estimate PEEPi in both controlled, assisted, and spontaneously ventilating patients. PMID:2670467

Hoffman, R A; Ershowsky, P; Krieger, B P

1989-09-01

345

Observational constraint on Jovian active longitude controlling decameter emissions  

NASA Astrophysics Data System (ADS)

The occurrence probability of the Io-controlled Jovian decameter radio emissions depends on both the central meridian longitude (CML) and the phase of the satellite Io. Recent investigations by Galopeau et al. (J. Geophys. Res. 112, 2007) have shown that some specific Jovian 'active' longitudes favour the radiation by considering that the emissions are produced near the local gyrofrequency, along an active magnetic field line carried away by Io along its revolution around Jupiter, within a hollow cone of constant angle. This model involves the cyclotron maser instability as the mechanism at the origin of the radio emission. The observed occurrence probability happens to be larger in some specific regions of the CML-Io phase diagram, the so-called Io-controlled emissions and well-known as Io-A, Io-B, Io-C and Io-D 'sources'. In the present investigation, we model four boxes representing the typical Io-controlled source regions in this diagram. We discuss the consequences and the constraints on the location of the Jovian active longitude at the origin of the Io-controlled radiation simultaneously for both hemispheres. The first results show that the active longitude model can only explain part of the emissions coming from restricted zones of the CML-Io phase diagram. This is particular the case for the emissions of the Io-D source.

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

2009-04-01

346

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

NASA Astrophysics Data System (ADS)

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.

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

347

Longitudinally Coherent Single-Spike Radiation from a Self-Amplified Spontaneous Emission Free-Electron Laser  

NASA Astrophysics Data System (ADS)

This work studies the production and measurement of longitudinally coherent, ultrashort pulses of light from a self-amplified spontaneous emission free-electron laser (SASE FEL) by using an energy-chirped electron beam in conjunction with a tapered undulator. This scheme effectively preserves the FEL gain only where an appropriate undulator taper compensates for the detuning experienced by an amplifying radiation spike as it slips forward in the electron beam rest frame. The simultaneous time and frequency-domain measurement of ultrashort pulses of light generated in this manner were made with an advanced transient-grating frequency-resolved optical gating (TG FROG) diagnostic, which has the potential to push ultrashort light pulse measurement at FEL facilities to shorter wavelength regimes. The theoretical framework presented in this dissertation has two components. The FEL theory presented here includes an analysis of the coupled wave and Vlasov equations, which are linearized in the one-dimensional case, and are solved in the frequency domain by the Laplace transform technique. The exponential gain regime for SASE FEL light is explored in detail to clearly identify concepts that are relevant to the energy-chirp and undulator tapering experiment. Some of these concepts are illustrated with fully three-dimensional, time-dependent numerical particle simulations using the FEL code GENESIS for the supportive case of ultrashort, low-charge electron beams. In addition, nonlinear optics, the foundation upon which all FROG diagnostics are built, is briefly explored using two complementary perspectives as they apply to the TG FROG geometry. The experimental section describes in detail the first direct time-domain measurements of a single coherent radiation spike from a SASE FEL amplifier employing the energy-chirped electron beam and tapered undulator technique at the SPARC FEL test facility in Frascati, Italy. Electron beams were accelerated and compressed using the velocity bunching technique, which leaves a residual energy-chirp in the longitudinal phase space. The energy-chirp was compensated by appropriately tapering individual undulator sections. This process was optimized at a resonant wavelength of ? = 530 nm. The ultrashort light pulses that were generated had a temporal full-width at half-maximum of 98 fs and a time-bandwidth product of TBP ˜ 1.2, indicating that the Fourier limit was nearly achieved. This experiment provides further insight into methods that can be used to shape the SASE FEL longitudinal profile and enhance coherence properties. In addition, the measurements were taken with an advanced, and relatively simple, TG FROG diagnostic that can potentially be used to measure ultrashort UV pulses at FEL facilities.

Marcus, Gabriel Andrew

348

Coal-fueled diesel emissions control technology development  

SciTech Connect

The objective of this project is to develop an emissions control system for a GE locomotive powered by a Coal Water Slurry (CWS) fuel diesel engine. The development effort is directed toward reducing particulate matter, SO[sub 2] and NO[sub x] emissions from the engine exhaust gas at 700--800F and 1-2 psig. The commercial system should be economically attractive while subject to limited space constraints. After testing various alternatives, a system composed of a barrier filter with sorbent injection ups was selected for controlling particulates, SO[sub 2] and NO[sub x] emissions. In bench scale and 500 acfm slip s tests, removal efficiencies greater than 90% for SO[sub 2] and 85% for NO[sub x] were achieved. Particulate emissions from the barrier filter are within NSPS limits.

Cook, C.; Gal, E.; Mengel, M.; Van Kleunen, W.

1993-01-01

349

Coal-fueled diesel emissions control technology development  

SciTech Connect

The objective of this project is to develop an emissions control system for a GE locomotive powered by a Coal Water Slurry (CWS) fuel diesel engine. The development effort is directed toward reducing particulate matter, SO{sub 2} and NO{sub x} emissions from the engine exhaust gas at 700--800F and 1-2 psig. The commercial system should be economically attractive while subject to limited space constraints. After testing various alternatives, a system composed of a barrier filter with sorbent injection ups was selected for controlling particulates, SO{sub 2} and NO{sub x} emissions. In bench scale and 500 acfm slip s tests, removal efficiencies greater than 90% for SO{sub 2} and 85% for NO{sub x} were achieved. Particulate emissions from the barrier filter are within NSPS limits.

Cook, C.; Gal, E.; Mengel, M.; Van Kleunen, W.

1993-03-01

350

The effect of ketamine on intracranial pressure during haemorrhagic shock under the conditions of both spontaneous breathing and controlled ventilation  

Microsoft Academic Search

Summary Seventeen piglets of both sexes, seven with O2\\/air-buprenorphine anaesthesia and controlled ventilation, and ten unanaesthetized animals with normal, spontaneous respiration, were used for the study. The intracranial pressure of both groups of animals was raised by insufflation of an epidural ballon and the arterial blood pressure was reduced to approximately 70% of the original value by controlled haemorrhage. 0.5

E. Pfenninger; A. Griinert; I. Bowdler; J. Kilian

1985-01-01

351

Mercury emissions control technologies for mixed waste thermal treatment  

Microsoft Academic Search

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

A. Chambers; M. Knecht; N. Soelberg; D. Eaton; D. Roberts; T. Broderick

1997-01-01

352

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...

353

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

SciTech Connect

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.

Rohringer, N

2008-08-08

354

Primary production control of methane emission from wetlands  

NASA Astrophysics Data System (ADS)

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.

Whiting, G. J.; Chanton, J. P.

1993-08-01

355

Design and control of a demand flow system assuring spontaneous breathing of a patient connected to an HFO ventilator.  

PubMed

Lung protective ventilation is intended to minimize the risk of ventilator induced lung injury and currently aimed at preservation of spontaneous breathing during mechanical ventilation. High-frequency oscillatory ventilation (HFOV) is a lung protective ventilation strategy. Commonly used high-frequency oscillatory (HFO) ventilators, SensorMedics 3100, were not designed to tolerate spontaneous breathing. Respiratory efforts in large pediatric and adult patients impose a high workload to the patient and may cause pressure swings that impede ventilator function. A Demand Flow System (DFS) was designed to facilitate spontaneous breathing during HFOV. Using a linear quadratic Gaussian state feedback controller, the DFS alters the inflow of gas into the ventilator circuit, so that it instantaneously compensates for the changes in mean airway pressure (MAP) in the ventilator circuit caused by spontaneous breathing. The undesired swings in MAP are thus eliminated. The DFS significantly reduces the imposed work of breathing and improves ventilator function. In a bench test the performance of the DFS was evaluated using a simulator ASL 5000. With the gas inflow controlled, MAP was returned to its preset value within 115 ms after the beginning of inspiration. The DFS might help to spread the use of HFOV in clinical practice. PMID:21859597

Roubík, Karel; Ráfl, Jakub; van Heerde, Marc; Markhorst, Dick G

2011-08-22

356

Controlled Trial of Chemoprevention Using COX-2 Inhibitors in an Avian Model of Spontaneous Ovarian Carcinogenesis.  

National Technical Information Service (NTIS)

While a strong rationale for chemoprevention of ovarian carcinoma exists, a mechanism for the comprehensive evaluation of novel compounds is severely impeded by the lack of a validated animal model of spontaneous ovarian carcinogenesis. At present, there ...

M. N. Barnes W. D. Berry

2005-01-01

357

Controlled Trial of Chemoprevention Using COX-2 Inhibitors in an Avian Model of Spontaneous Ovarian Carcinogesis.  

National Technical Information Service (NTIS)

While a strong rationale for chemoprevention of ovarian carcinoma exists, a mechanism for the comprehensive evaluation of novel compounds is severely impeded by the lack of a validated animal model of spontaneous ovarian carcinogenesis. At present, there ...

M. N. Barnes W. D. Berry

2006-01-01

358

Iron Foundry Cupola Recuperative Emission Control Demonstration.  

National Technical Information Service (NTIS)

The report gives results of a project intended to demonstrate the use of a dry, solid-media heat exchanger for the production of hot blast air for the cupola as an integral part of the air pollution control system. Economic advantages--in the form of redu...

J. F. Turner

1976-01-01

359

63 FR 15006 - National Emission Standards for Hazardous Air Pollutants and Control Techniques Guideline...  

Federal Register 2010, 2011, 2012, 2013

...National Emission Standards for Hazardous Air Pollutants and Control Techniques Guideline...National Emission Standards for Hazardous Air Pollutants and Control Techniques Guideline...national emission standards for hazardous air pollutants (NESHAP) for aerospace...

1998-03-27

360

24 CFR 3280.308 - Formaldehyde emission controls for certain wood products.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Formaldehyde emission controls for certain wood...Construction Requirements § 3280.308 Formaldehyde emission controls for certain wood products. (a) Formaldehyde emission levels. All...

2013-04-01

361

24 CFR 3280.308 - Formaldehyde emission controls for certain wood products.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Formaldehyde emission controls for certain wood...Construction Requirements § 3280.308 Formaldehyde emission controls for certain wood products. (a) Formaldehyde emission levels. All...

2009-04-01

362

24 CFR 3280.308 - Formaldehyde emission controls for certain wood products.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Formaldehyde emission controls for certain wood...Construction Requirements § 3280.308 Formaldehyde emission controls for certain wood products. (a) Formaldehyde emission levels. All...

2010-04-01

363

Spontaneous ordering, strain control and mutlifunctionality in vertical nanocomposite heteroepitaxial films  

Microsoft Academic Search

Two-phase nanocomposite heteroepitaxial films with vertical microstructures hold great promise for various (multi)functional (e.g. multiferroic) electronic device applications. With the aim of creating addressable arrays, it is necesary to form spontaneously ordered structures over large areas. However, such structures have not, so far, been demonstrated. We have recently shown remarkable spontaneously ordered phase assemblies and find that these structures form

J. L. MacManus-Driscoll; A. Fouchet; P. Zerrer; R. Yu; H. Wang; H. Yang; J. Yoon; Q. X. Jia

2008-01-01

364

Spontaneous Ordering, Strain Control, and Multifunctionality in Vertical Nanocomposite Heteroepitaxial Films  

Microsoft Academic Search

Two-phase nanocomposite heteroepitaxial films with vertical microstructures hold great promise for various (multi)functional (e.g., multiferroic) electronic device applications. With the aim of creating addressable arrays, it is necessary to form spontaneously ordered structures over large areas. However, such structures have not, so far, been demonstrated. We have recently produced remarkable spontaneously ordered phase assemblies and find that these structures form

Arnaud Fouchet; Haiyan Wang; Hao Yang; Jongsik Yoon; Quanxi Jia; Judith Macmanus-driscoll

2009-01-01

365

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

SciTech Connect

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.

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

366

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

SciTech Connect

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.

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. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); California Institute of Technology, Pasadena, California 91125 (United States); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); University of Wisconsin, Madison, Wisconsin 53706 (United States)

2005-05-15

367

Emission control from stationary power sources (control of NO\\/sub x\\/ emissions from liquid fuel-fired industrial boilers)  

Microsoft Academic Search

Modification of the combustion process is an effective means of controlling nitrogen oxides and other atmospheric pollutant emissions from stationary combustion sources. Discussed is the influence of fuel oil composition and spray characteristics on the formation and control of nitrogen oxides. Detailed testing of 15 liquid fuels was conducted, using a 20 kw tunnel furnace. Staged combustion was shown to

D. W. Pershing; G. C. England; M. P. Heap; G. Flament

1980-01-01

368

Wavefront analysis of nonlinear self-amplified spontaneous-emission free-electron laser harmonics in the single-shot regime.  

PubMed

The single-shot spatial characteristics of the vacuum ultraviolet self-amplified spontaneous emission of a free electron laser (FEL) is measured at different stages of amplification up to saturation with a Hartmann wavefront sensor. We show that the fundamental radiation at 61.5 nm tends towards a single-mode behavior as getting closer to saturation. The measurements are found in good agreement with simulations and theory. A near diffraction limited wavefront was measured. The analysis of Fresnel diffraction through the Hartmann wavefront sensor hole array also provides some further insight for the evaluation of the FEL transverse coherence, of high importance for various applications. PMID:21770510

Bachelard, R; Mercère, P; Idir, M; Couprie, M-E; Labat, M; Chubar, O; Lambert, G; Zeitoun, Ph; Kimura, H; Ohashi, H; Higashiya, A; Yabashi, M; Nagasono, M; Hara, T; Ishikawa, T

2011-06-08

369

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)

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.

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

2012-08-01

370

Coal-fueled diesel technology development Emissions Control  

SciTech Connect

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.

Van Kleunen, W.; Kaldor, S.; Gal, E.; Mengel, M.; Arnold, M.

1994-01-01

371

Mercury emissions control technologies for mixed waste thermal treatment  

SciTech Connect

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.

Chambers, A.; Knecht, M.; Soelberg, N.; Eaton, D. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Roberts, D.; Broderick, T. [ADA Technologies, Englewood, CO (United States)

1997-12-31

372

APTI Course 415: Control of gaseous emissions. Instructor's guide  

SciTech Connect

The Instructor's Guide is to be used for the Air Pollution Training Institute Course 415, Control of Gaseous Emissions. The publication contains complete information for conducting a 4-day course in gaseous emission control. The guide contains course goals and objectives, preparation instructions, lesson plans, exams and exam keys, and solution to the problem sets. The lesson plans include keys to 35 mm slides developed for the course and suggested reference materials. The publication is intended for use in conjunction with the Student Manual (PB91-101709) and the Student Workbook (PB91-101758) for APTI Course 415.

Joseph, J.; Beachler, D.; Jahnke, J.; Leslie, M.; Henry, J.

1981-05-01

373

Controlling formaldehyde emissions with boiler ash.  

PubMed

Fluidized wood ash reduces formaldehyde in air from about 20 to <1 ppmv. Methanol is removed to a much lower extent. The efficiency of formaldehyde reduction increases with increasing moisture content of the ash. Sorption of formaldehyde to ash can be substantially accounted for by partitioning to the water contained in the ash followed by rate-controlling binding to the ash solids. Adsorption occurs at temperatures of up to 165 degrees C; oxidation predominates thereafter. It is proposed that formaldehyde could be stripped from an air stream in a fluidized bed containing ash, which could then be returned to a boiler to incinerate the formaldehyde. PMID:16053116

Cowan, Jennifer; Abu-Daabes, Malyuba; Banerjee, Sujit

2005-07-01

374

Coherently controlled emission from two atoms dressed via a standing wave laser field  

NASA Astrophysics Data System (ADS)

The influence of the standing wave amplitude on the resonance fluorescence of a three-level system of radiators is discussed. Great attention is devoted to the peculiarities of dressed states in the standing wave and the exchange integrals between two atoms situated in the anti-nodes or the nodes. The correlation functions of emitted photons at two dressed frequencies were obtained. It is shown that in the case when the distance between two atoms is smaller than the wavelength of the field, the emitted photons are strongly correlated. As was observed, for large values of laser field intensity, the control of spontaneous emission is possible at two frequencies as well as the atom-atom interaction process. The dependence of the fluorescent light spectrum as a function of the position of two atoms dressed in the standing wave is investigated.

Enaki, N. A.; Ciobanu, N.; Orszag, M.

2011-11-01

375

Resource recovery emission control system comparison  

SciTech Connect

The response to the necessity for control of acid gases, fine particulate, mercury vapor, and organics present in the flue gas emitted from the incineration of municipal solid waste and hazardous waste has followed the conventional steps for emerging technology. These are: adaptation of existing equipment and its failure; development of new technologies; fear of failure of new technologies; modification of technology; overcoming of concerns by extended operation. It has been established that incineration of wastes produces a flue gas containing: particulates including fine particulates in which toxic heavy metals and organics are concentrated; acid gases, primarily HCl and SO/sub 2/ with quantities produced increasing with time; mercury and organic vapor; high concentrations of incandescent particles. The initial reponse was to apply existing types of equipment to the problem.

Teller, A.J.

1985-01-01

376

Cliffside 6 integrated emissions control system  

SciTech Connect

The article takes an inside look into the environmental hardware going into one of the highest profile coal-fired power plants projects in the US, a new 800 MW supercritical coal-fired facility at Cliffside, NC, Unit C6. This is currently under construction and scheduled to be in commercial service in 2012. To evaluate the alternative air quality control system (AQCS) options, Duke Energy established a cross-functional team and used a decision analysis process to select the 'best balanced choice'. Alstom's integrated AQCS which combines dry and wet flue gas desulfurization systems was the best balanced choice. Replacing an ESP with a spray dryer absorber achieved major cost savings and eliminated the need for wastewater treatment. 1 ref., 2 photos.

McGinnis, D.G.; Rader, P.C.; Gansley, R.R.; Wang, W. [Duke Energy, Charlotte, NC (United States)

2009-04-15

377

Angular, energy, and mass correlations for spontaneous fission of /sup 252/Cf with emission of /sup 3/H, /sup 4/He, and /sup 6/He nuclei  

SciTech Connect

Energy spectra and yields were measured for /sup 3/H, /sup 4/He, /sup 6/He nuclei and Li and Be isotopes, released during spontaneous fission of /sup 252/Cf. Energy and angular distributions were determined for /sup 3/H, /sup 4/He, and /sup 6/He in coincidence with heavy fission fragments, in the range 60--120/sup 0/ of particle emission angles relative to the light fragment direction of motion. Mass distributions were obtained for heavy fragments in ternary fission, and energy and angular correlations were determined for charged particles and fission fragments in the range 1.0--2.0 of mass ratios. The experimental data are compared with analogous results obtained from detailed investigation of thermal-neutron-induced fission of /sup 235/U with emission of ..cap alpha..-particles, and with existing trajectory calculations for ternary fission of nuclei.

Grache-dieresisv, V.T.; Gusev, Y.I.; Seliverstov, D.M.

1988-03-01

378

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)

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.

Moraes, Thiago A.; Barlow, Peter W.; Klingelé, Emile; Gallep, Cristiano M.

2012-06-01

379

Emissions, combustion dynamics, and control of a multiple swirl combustor  

NASA Astrophysics Data System (ADS)

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.

Li, Guoqiang

380

[Spontaneous closure of a intracraneal dural arteriovenous fistula by controlled hypotension during a general anesthesia procedure. A case report].  

PubMed

Intracranial dural arteriovenous fistulas (DAVF) are arteriovenous communications within the duramater, which seem to be pathophysiologically related to a venous sinus thrombosis. DAVF may require invasive treatment, although rarely spontaneous occlusion has been reported. The present case is a 48-year-old male with a diagnosed type III DAVF of the right lateral sinus. Complete endovascular embolization was not possible to perform, so he was considered a candidate for surgical treatment. During perioperative management, under general anesthesia, the intraoperative arteriographyc monitoritation showed a spontaneous closure of the DAVF after induced controlled hypotension, resulting in complete cure. We conclude that controlled hypotension could become an alternative for treatment of DAVF in high risk patients or when there is no chance for embolization.patients or when there is no chance for embolization. Neurología 2003;18(10):746-749 PMID:14648352

Ornaque, I; Alonso, P; Martí Valeri, C; de Miquel, M A; Cambra, R; Gabarrós, A; Conesa, G

2003-12-01

381

Emission control valve with internal spring  

SciTech Connect

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.

Betterton, J.T.; Glover, A.H.; McKee, T.S.; Romanczuk, C.S.

1990-03-06

382

Controlled drop emission by wetting properties in driven liquid filaments  

NASA Astrophysics Data System (ADS)

The controlled formation of micrometre-sized drops is of great importance to many technological applications. Here we present a wetting-based destabilization mechanism of forced microfilaments on either hydrophilic or hydrophobic stripes that leads to the periodic emission of droplets. The drop emission mechanism is triggered above the maximum critical forcing at which wetting, capillarity, viscous friction and gravity can balance to sustain a stable driven contact line. The corresponding critical filament velocity is predicted as a function of the static wetting angle, which can be tuned through the substrate behaviour, and shows a strong dependence on the filament size. This sensitivity explains the qualitative difference in the critical velocity between hydrophilic and hydrophobic stripes, and accounts for previous experimental results of splashing solids. We demonstrate that this mechanism can be used to control independently the drop size and emission period, opening the possibility of highly monodisperse and flexible drop production techniques in open microfluidic geometries.

Ledesma-Aguilar, R.; Nistal, R.; Hernández-Machado, A.; Pagonabarraga, I.

2011-05-01

383

Control of the shape of the spatial mode function of photons generated in noncollinear spontaneous parametric down-conversion  

SciTech Connect

We show experimentally how the spatial shape of the pump beam controls the ellipticity of the spatial mode function in noncollinear spontaneous parametric down-conversion. The degree of ellipticity depends on the pump beam width, especially for highly focused beams. We introduce an effective length, the so-called noncollinear length, that determines the importance of the ellipticity of the spatial mode function. We also discuss the ellipticity induced by the spectrum of the pump beam.

Molina-Terriza, Gabriel; Minardi, Stefano; Osorio, Clara I. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona) (Spain); Deyanova, Yana; Hendrych, Martin; Torres, Juan P. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona) (Spain); Department of Signal Theory and Communications, Universitat Politecnica de Catalunya, 08034 Barcelona (Spain)

2005-12-15

384

Brief Report: Pilot Randomized Controlled Trial of Reciprocal Imitation Training for Teaching Elicited and Spontaneous Imitation to Children with Autism  

Microsoft Academic Search

Children with autism exhibit significant deficits in imitation skills. Reciprocal Imitation Training (RIT), a naturalistic\\u000a imitation intervention, was developed to teach young children with autism to imitate during play. This study used a randomized\\u000a controlled trial to evaluate the efficacy of RIT on elicited and spontaneous imitation skills in 21 young children with autism.\\u000a Results found that children in the

Brooke Ingersoll

2010-01-01

385

Enhanced control of mercury emissions through modified speciation  

SciTech Connect

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}.

Livengood, C.D.; Mendelsohn, M.H.

1997-07-01

386

NOx Sensor for Direct Injection Emission Control  

SciTech Connect

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.

Betteridge, William J

2006-02-28

387

Optical gain and spontaneous emission of strain-compensated InGaN-AlGaN quantum wells including carrier screening effect  

NASA Astrophysics Data System (ADS)

Strain-compensated InGaN quantum well (QW) active region employing tensile AlGaN barriers was analyzed as improved gain media for laser diodes emitting at 430-440 nm by taking into account the carrier screening effect. The use of strain-compensated InGaN-AlGaN structure is advantageous because the tensile barriers compensate the compressive strain in the InGaN QW and the larger band offset allows high temperature operation. The band structure is calculated by using a 6-band k times p formalism, taking into account valence band mixing, strain effect, spontaneous and piezoelectric polarizations. The carrier screening effect is incorporated in the calculation, which is solved self-consistently. The spontaneous emission spectra show a significant improvement of the radiative emission for strain-compensated structure. The optical gain analysis shows enhancement in the peak optical gain for the strain-compensated QW structures. Threshold analysis of both the conventional InGaN-GaN QW and strain-compensated InGaN-AlGaN QW active regions indicate a reduction in the threshold carrier density and threshold current density for diode laser employing the strain-compensated QW as its active region.

Zhao, Hongping; Arif, Ronald A.; Ee, Yik Khoon; Tansu, Nelson

2008-03-01

388

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. ...

389

Kontrol af emissionsopgoerelse. (Control investigation of methods of emission estimation).  

National Technical Information Service (NTIS)

The aim was to carry out a control of the various methods of calculation of emission (in kg per time unit) of sulphur dioxide and nitrogen oxides from fossil-fuelled power plants in order to point out possible sources of errors. A number of discrepancies ...

P. Blinksbjerg O. Stausgaard Nielsen

1993-01-01

390

Alternative Control Technology Document for Bakery Oven Emissions.  

National Technical Information Service (NTIS)

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 documen...

C. W. Sanford

1992-01-01

391

Jovian longitudinal control of Io-related radio emissions  

Microsoft Academic Search

We propose a theoretical model to explain the control that Jupiter's rotational phase exercizes over Io-related radio emissions. Longitudinal asymmetries in the conductivity and electron content of Jupiter's ionosphere are generated by variations in the mirror altitudes of energetic electrons trapped in Jupiter's magnetosphere. Energetic electrons are absorbed by the atmosphere preferentially in regions where, because of higher-order magnetic moments,

A. J. Dessler; T. W. Hill

1979-01-01

392

PHYSICAL COAL CLEANING FOR UTILITY BOILER SO2 EMISSION CONTROL  

EPA Science Inventory

The report examines physical coal cleaning as a control technique for sulfur oxides emissions. It includes an analysis of the availability of low-sulfur coal and of coal cleanable to compliance levels for alternate New Source Performance Standards (NSPS). Various alternatives to ...

393

Health and climate policy impacts on sulfur emission control  

Microsoft Academic Search

Sulfate aerosol from burning fossil fuels not only has strong cooling effects on the Earth's climate but also imposes substantial costs on human health. To assess the impact of addressing air pollution on climate policy, we incorporate both the climate and health effects of sulfate aerosol into an integrated-assessment model of fossil fuel emission control. Our simulations show that a

Yi Ming; Lynn M. Russell; David F. Bradford

2005-01-01

394

Controlled Vacuum Breakdown in Carbon Nanotube Field Emission  

Microsoft Academic Search

We report a physical mechanism of controlling vacuum breakdown in field emission from carbon nanotubes (CNTs). The thermal evaporation or runaway of CNT emitters is considered to be responsible for destructive vacuum breakdowns due to an overcurrent through electronically shorted circuits, where misaligned or irregularly long CNT emitters were found. The occurrence of the destructive breakdown, however, could be under

Chan-Wook Baik; Jeonghee Lee; Deuk Seok Chung; Jun Hee Choi; In-Taek Han; Ha Jin Kim; Shang Hyeun Park; Sun Il Kim; Yong Wan Jin; Jong-Min Kim; Jin Young Kim; Segi Yu; Kyu-Ha Jang; Gun-Sik Park

2007-01-01

395

Particulate Emissions from a Pre-Emissions Control Era Spark-Ignition Vehicle: A Historical Benchmark  

SciTech Connect

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.

John M.E. Storey; C. Scott Sluder; Douglas A. Blom; Erin Higinbotham

2000-06-19

396

Revisiting factors controlling methane emissions from high-arctic tundra  

NASA Astrophysics Data System (ADS)

Among the numerous studies of methane emission from northern wetlands the number of measurements carried on at high latitudes (north of the Arctic Circle) is very limited, and within these there is a bias towards studies of the growing season. Here we present results of five years 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 period. The measurements show clear seasonal dynamics in methane emission. In the beginning of the growing season increase in CH4 fluxes was strongly related to the date of snow melt. The greatest variation in fluxes between the study years were 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 at least during three out of five years 2006 - 2010. The accumulated 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 investigate the drivers and links between growing season and late season fluxes. The reported surprising seasonal dynamics of CH4 emissions at this site show that there are important occasions where conventional knowledge on factors controlling methane emissions is overruled by other processes, acting in longer than seasonal time scales. Our findings suggest the importance of multiyear studies with continued focus on shoulder seasons.

Mastepanov, Mikhail; Sigsgaard, Charlotte; Tagesson, Torbern; Strom, Lena; Tamstorf, Mikkel; Lund, Magnus; Christensen, Torben

2013-04-01

397

Gamma Ray Multiplicity Comparison of a 2Neutron and a 4Neutron Emission ^252Cf Spontaneous Fission  

Microsoft Academic Search

The correlation between gamma-ray multiplicity and neutron multiplicity in the fission process is not currently well known. Competing theories predict opposite correlations and experiments have measured only average properties. We have measured the gamma-ray multiplicity spectrum of ^252Cf spontaneous fission using the LiBerACE array, comprised of six high-purity germanium (HPGe) Clover detectors, each surrounded by 16 bismuth-germanate (BGO) detectors. The

D. L. Bleuel; L. A. Bernstein; J. T. Burke; M. D. Heffner; E. B. Norman; N. D. Scielzo; S. A. Sheets; N. J. Snyderman; M. A. Stoyer; M. Wiedeking; J. Gibelin; L. W. Phair; J. Mintz

2008-01-01

398

Genetic Control of Spontaneous Arthritis in a Four-Way Advanced Intercross Line  

PubMed Central

Identifying the genetic basis of complex diseases, such as rheumatoid arthritis, remains a challenge that requires experimental models to reduce the genetic and environmental variability. Numerous loci for arthritis have been identified in induced animal models; however, few spontaneous models have been genetically studied. Therefore, we generated a four-way advanced intercross line (AIL) from four inbred strains, including BXD2/TyJ which spontaneously develops autoimmune arthritis. A genome-wide scan for spontaneous arthritis was performed in a cohort of 366 mice of the fourth generation (G4) of this cross. Five loci contributing to clinical phenotypes were identified in chromosomes 3, 7, 13, 18, and X. Three of the loci found in this study, confirm previously identified loci; whereas two of them are novel loci. Interesting candidate genes for the loci are highlighted. This study provides a genetic overview of spontaneous arthritis in mice and aids to solve the genetic etiology of rheumatoid arthritis and to gain a better understanding of the disease.

Ranea, Laura Mellado; de Castro Marques, Andreia; Moller, Steffen; Gupta, Yask; Ibrahim, Saleh M.

2013-01-01

399

Time-varying analysis of autonomic control in response to spontaneous sighs in sickle cell anemia  

Microsoft Academic Search

Sickle cell anemia (SCA) is a genetic disease which is characterized by painful episodes of vascular occlusions. In the present study, we investigated a potential contribution of the autonomic nervous system (ANS) in initiating such episodes. We observed prominent decreases in microvascular perfusion in response to spontaneous sighs, which may increase the likelihood of red blood cell polymerization followed by

S. Sangkatumvong; T. D. Coates; J. C. Wood; H. J. Meiselman; R. Kato; J. A. Detterich; A. Bush; M. C. K. Khoo

2010-01-01

400

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

ERIC Educational Resources Information Center

|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…

Spencer, Trina D.; Higbee, Thomas S.

2012-01-01

401

Control of Trace Metal Emissions During Coal Combustion  

SciTech Connect

Emissions of toxic trace metals in the form of metal fumes or submicron particulates from a coal-fired combustion source have received greater environmental and regulatory concern over the past years. Current practice of controlling these emissions is to collect them at the cold-end of the process by air-pollution control devices (APCDs) such as electrostatic precipitators and baghouses. However, trace metal fumes may not always be effectively collected by these devices because the formed fumes are extremely small. The proposed research is to explore the opportunities for improved control of toxic trace metal emissions, alternatively, at the hot-end of the coal combustion process, i.e., in the combustion chamber. The technology proposed is to prevent the metal fumes from forming during the process, which would effectively eliminate the metal emission problems. Specifically, the technology is to employ suitable sorbents to (1) reduce the amount of metal volatilization during combustion and (2) capture volatilized metal vapors. The objectives of the project are to demonstrate the technology and to characterize the metal capture process during coal combustion in a fluidized bed combustor.

Thomas C. Ho

1997-07-01

402

Control of Trace Metal Emissions During Coal Combustion  

SciTech Connect

Emissions of toxic trace metals in the form of metal fumes or submicron particulates from a coal-fired combustion source have received greater environmental and regulatory concern over the past years. Current practice of controlling these emissions is to collect them at the cold-end of the process by air-pollution control devices (APCDs) such as electrostatic precipitators and baghouses. However, trace metal fumes may not always be effectively collected by these devices because the formed fumes are extremely small. The proposed research is to explore the opportunities for improved control of toxic trace metal emissions, alternatively, at the hot-end of the coal combustion process, i.e., in the combustion chamber. The technology proposed is to prevent the metal fumes from forming during the process, which would effectively eliminate the metal emission problems. Specifically, the technology is to employ suitable sorbents to (1) reduce the amount of metal volatilization during combustion and (2) capture volatilized metal vapors. The objectives of the project are to demonstrate the technology and to characterize the metal capture process during coal combustion in a fluidized bed combustor. The project was started on July 1, 1994 and this is the thirteenth quarterly technical progress report. Specifically, the following progress has been made during this performance period from July 1, 1997 through September 30, 1997.

Thomas C. Ho

1997-10-01

403

A new self-controlled case series method for analyzing spontaneous reports of adverse events after vaccination.  

PubMed

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

Escolano, S; Hill, C; Tubert-Bitter, P

2013-09-07

404

76 FR 51901 - Approval and Promulgation of Air Quality Implementation Plans; Ohio; Control of Emissions of...  

Federal Register 2010, 2011, 2012, 2013

...Implementation Plans; Ohio; Control of Emissions of Organic Materials That Are Not Regulated by Volatile Organic Compound Reasonably Available Control Technology...3745-21-07, ``Control of emissions of organic materials from stationary sources...

2011-08-19

405

Soil acidification in China: Is controlling SO2 emissions enough?  

NASA Astrophysics Data System (ADS)

Facing challenges of regional air pollution, China has been aggressively implementing flue gas desulfurization (FGD) and phasing out small inefficient units in the power sector, in order to achieve the national goal of 10% reduction in sulfur dioxide (SO2) emissions from 2005 to 2010. In this study, the effect of these measures on soil acidification is explored. An integrated methodology is used, combining emission inventory data, emission forecasts, air quality modeling, and ecological sensitivities indicated by critical load. National emissions of SO2, oxides of nitrogen (NOX), particulate matter (PM), and ammonia (NH3) in 2005 were estimated to be 30.7, 19.6, 31.3 and 16.6 Mt, respectively. Implementation of existing policy will lead to reductions in SO2 and PM emissions, while those of NOX and NH3 will continue to rise, even under tentatively proposed control measures. In 2005, the critical load for soil acidification caused by sulfur deposition (indicated by CLmax(S)) was exceeded in 28% of the country’s territory, mainly in eastern and south-central China. The area in exceedance will decrease to 26% and 20% in 2010 and 2020, respectively, given implementation of current plans for emission reductions. However, the exceedance of the critical load for nitrogen (combining effects of eutrophication and acidification, indicated by CL(N)) will double from 2005 to 2020 due to increased NOX and NH3 emissions. Combining the acidification effects of S and N(indicated by CL(S)), the benefits of SO2 reductions during 2005-2010 will almost be negated by increased N emissions. Therefore abatement of N emissions (both NOX and NH3) and deposition will be a major challenge to China, requiring both policy development and technology investments. To mitigate acidification in the future, China needs a multi-pollutant control strategy that integrates measures to reduce S, N and PM. Exceedances of critical loads for acidification and nutrient nitrogen in 2005, 2010, and 2020. Critical load exceedance in 2005, 2010 and 2020

Zhao, Y.; Duan, L.; Xing, J.; Larssen, T.; Nielsen, C. P.; Hao, J.

2009-12-01

406

Emissions from premixed charge compression ignition (PCCI) combustion and affect on emission control devices  

SciTech Connect

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.

Parks, II, James E [ORNL; Kass, Michael D [ORNL; Huff, Shean P [ORNL; Barone, Teresa L [ORNL; Lewis Sr, Samuel Arthur [ORNL; Prikhodko, Vitaly Y [ORNL; Storey, John Morse [ORNL

2010-01-01

407

Cost and Engineering Study - Control of Volatile Organic Emissions from Whiskey Warehousing.  

National Technical Information Service (NTIS)

This document provides cost and engineering information on control of volatile organic emissions from whiskey warehousing. Included are a description of whiskey aging, warehousing, and of volatile organic emissions from warehousing; a development of emiss...

D. C. Mascone

1978-01-01

408

Control of volatile organic compound emissions from batch processes. Alternative control techniques information document. Final report  

SciTech Connect

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.

Not Available

1994-02-01

409

Control of mercury emissions from coal-fired boilers  

SciTech Connect

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.

Huang, H.S.; Livengood, C.D.

1992-09-01

410

Control of mercury emissions from coal-fired boilers  

SciTech Connect

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.

Huang, H.S.; Livengood, C.D.

1992-01-01

411

Pronounced Purcell enhancement of spontaneous emission in CdTe/ZnTe quantum dots embedded in micropillar cavities  

NASA Astrophysics Data System (ADS)

The coupling of CdTe/ZnTe quantum dot (QD) emission to micropillar cavity eigenmodes in the weak coupling regime is demonstrated. We analyze photoluminescence spectra of QDs embedded in monolithic micropillar cavities based on Bragg mirrors which contain MgSe/ZnTe/MgTe superlattices as low-index material. The pillar emission shows pronounced cavity eigenmodes, and their spectral shape is in good agreement with simulations. QD emission in resonance with the cavity mode is shown to be efficiently guided toward the detector, and an experimental Purcell enhancement by a factor of 5.7 is determined, confirming theoretical expectations.

Jakubczyk, T.; Pacuski, W.; Smole?ski, T.; Golnik, A.; Florian, M.; Jahnke, F.; Kruse, C.; Hommel, D.; Kossacki, P.

2012-09-01

412

LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL  

SciTech Connect

''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.

Don Augenstein

1999-01-11

413

Health and climate policy impacts on sulfur emission control  

NASA Astrophysics Data System (ADS)

Sulfate aerosol from burning fossil fuels not only has strong cooling effects on the Earth's climate but also imposes substantial costs on human health. To assess the impact of addressing air pollution on climate policy, we incorporate both the climate and health effects of sulfate aerosol into an integrated-assessment model of fossil fuel emission control. Our simulations show that a policy that adjusts fossil fuel and sulfur emissions to address both warming and health simultaneously will support more stringent fossil fuel and sulfur controls. The combination of both climate and health objectives leads to an acceleration of global warming in the 21st century as a result of the short-term climate response to the decreased cooling from the immediate removal of short-lived sulfate aerosol. In the long term (more than 100 years), reducing sulfate aerosol emissions requires that we decrease fossil fuel combustion in general, thereby removing some of the coemitted carbon emissions and leading to a reduction in global warming.

Ming, Yi; Russell, Lynn M.; Bradford, David F.

2005-12-01

414

40 CFR 63.3555 - How do I determine the outlet THC emissions and add-on control device emission destruction or...  

Code of Federal Regulations, 2010 CFR

... false How do I determine the outlet THC emissions and add-on control device emission...63.3555 How do I determine the outlet THC emissions and add-on control device emission...this section to determine either the outlet THC emissions or add-on control device...

2009-07-01

415

40 CFR 63.3555 - How do I determine the outlet THC emissions and add-on control device emission destruction or...  

Code of Federal Regulations, 2010 CFR

...2010-07-01 true How do I determine the outlet THC emissions and add-on control device emission...63.3555 How do I determine the outlet THC emissions and add-on control device emission...this section to determine either the outlet THC emissions or add-on control device...

2010-07-01

416

On-demand optogenetic control of spontaneous seizures in temporal lobe epilepsy  

PubMed Central

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.

Krook-Magnuson, Esther; Armstrong, Caren; Oijala, Mikko; Soltesz, Ivan

2013-01-01

417

On-demand optogenetic control of spontaneous seizures in temporal lobe epilepsy.  

PubMed

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

Krook-Magnuson, Esther; Armstrong, Caren; Oijala, Mikko; Soltesz, Ivan

2013-01-01

418

Revisiting factors controlling methane emissions from high-Arctic tundra  

NASA Astrophysics Data System (ADS)

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.

Mastepanov, M.; Sigsgaard, C.; Tagesson, T.; Ström, L.; Tamstorf, M. P.; Lund, M.; Christensen, T. R.

2013-07-01

419

Inhibitory control and l2 proficiency modulate bilingual language production: evidence from spontaneous monologue and dialogue speech.  

PubMed

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 English-French and French-English 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

Pivneva, Irina; Palmer, Caroline; Titone, Debra

2012-03-16

420

The Effect of Static Ear Canal Pressure on Human Spontaneous Otoacoustic Emissions: Spectral Width as a Measure of the Intra-cochlear Oscillation Amplitude  

PubMed Central

Spontaneous otoacoustic emissions can be detected as peaks in the Fourier spectrum of a microphone signal recorded from the ear canal. The height, center frequency, and spectral width of SOAE peaks changed when a static pressure was applied to the ear canal. Most commonly, with either increasing or decreasing static pressure, the frequency increased, the amplitude decreased, and the width increased. These changes are believed to result from changes in the middle ear properties. Specifically, reduced middle ear transmission is assumed to attenuate the amplitude of emissions. We reconsidered this explanation by investigating the relation between peak height and width. We showed that the spectral width of SOAE peaks is approximately proportional to \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ 1/\\sqrt {{{\\hbox{peak}}\\;{\\hbox{height}}}} $$\\end{document}. This is consistent with a (Rayleigh) oscillator model in which broadening of the SOAE peak is caused by broadband intra-cochlear noise, which is assumed to be independent of static ear canal pressure. The relation between emission peak height and width implicates that the intra-cochlear oscillation amplitude attentuates relative to the intra-cochlear noise level when a static ear canal pressure is applied. Apparently, ear canal static pressure directly affects the active mechanics in the inner ear.

Maat, Bert; de Kleine, Emile

2010-01-01

421

Neutron and Prompt Gamma Ray Emission in the Proton Induced Fission of 239Np and 243Am and Spontaneous Fission of 252Cf  

NASA Astrophysics Data System (ADS)

Average prescission < Mnpre > and postscission < Mnpost > neutron multiplicities as well as average ?-ray multiplicity , average energy emitted by ?-rays and average energy per one gamma quantum as a function of mass and total kinetic energy (TKE) of fission fragments were measured in proton induced reactions p+242Pu?243Am, p+238U?239Np (at proton energy Ep=13, 20 and 55 MeV) and spontaneous fission of 252Cf. The solid angle aberration and the Doppler shift in the laboratory angular distribution of ?-ray emission were utilized to obtain the number and energy of ?-rays as functions of single fragment mass. The results in the case of 252Cf, for both average number and average energy as functions of single fragment mass, are characterized by a sawtooth behavior similar to that which is well known for neutron emission. The similar behavior is seen for proton induced fission of 239Np and 243Am. The fragment mass dependence < Mnpost > (m) and (m) show a clear sawtooth structure that is gradually washed out with increasing proton energy Ep. Using the response matrix techniques we were able to distinguish between the statistical dipole (E1) and collective quadrupole (E2) ?-ray emission of single fission fragments.

Krupa, L.; Kniajeva, G. N.; Kliman, J.; Bogatchev, A. A.; Chubarian, G. M.; Dorvaux, O.; Itkis, I. M.; Itkis, M. G.; Khlebnikov, S.; Kondratiev, N. A.; Kozulin, E. M.; Lyapin, V.; Materna, T.; Rubchenia, W.; Pokrovsky, I. V.; Trzaska, W.; Vakhtin, D.; Voskressensky, V. M.

2005-09-01

422

High guided mode-cavity mode coupling for an efficient extraction of spontaneous emission of a single quantum dot embedded in a photonic crystal nanobeam cavity  

NASA Astrophysics Data System (ADS)

We demonstrate efficient extraction of a single InAs quantum dot spontaneous emission through an air-suspended waveguide to which a photonic crystal nanobeam cavity is coupled. First, the quantum dot emission into the cavity mode is enhanced due to a high Purcell effect arising from a large quality factor and a small mode volume of the cavity mode. Second, the cavity photons can be efficiently transferred to the guided mode by optimizing the design of a structure that exhibits a high coupling rate between the two modes. This configuration has lead to the observation of a high extraction efficiency (79%) of the quantum dot emission through the waveguide. Moreover, as a result of the high extraction efficiency to the guided mode, the unwanted microphotoluminescence coupling to the free space modes and detected from the top surface of the sample is strongly suppressed. Indeed, we show that it exhibits a negative peak as a function of the detuning between the cavity mode energy and the quantum dot transition energy.

Enderlin, Alexandre; Ota, Yasutomo; Ohta, Ryuichi; Kumagai, Naoto; Ishida, Satomi; Iwamoto, Satoshi; Arakawa, Yasuhiko

2012-08-01

423

The use of molten salts in emission control  

Microsoft Academic Search

The use of molten salts in emission control was studied with a stainless steel salt bath scrubber or incinerator containing alkali sulfates, with lithium sulfate added to form a melt at 840°F and to inhibit the adsorption of water under ambient conditions. The system removed submicron particulates with 2.5 by wt of the liquid required in a water scrubber and

Greenberg

1979-01-01

424

Conceptual designs of a 50 nm FEL (free-electron laser) oscillator and a 20-40 nm SASE (self-amplified spontaneous emission) amplifier  

SciTech Connect

This paper consists of two parts: the conceptual design and optical performance characteristics of a grazing angle-of-incidence ring resonator utilizing multifaceted metal mirrors for use with a 50 nm rf-linac-driven XUV FEL oscillator; and electron beam and wiggler requirements for a self-amplified spontaneous emission (SASE) amplifier to produce high power in the 20 to 40 nm wavelength range. The basis for these studies is the 3-d FEL simulation code FELEX which is used to derive tolerances on mirror figure and thermal distortion, alignment sensitivity, and alternative output coupling methods. The sensitivity of the output characteristics of an XUV FEL SASE amplifier to wiggler field errors is also studied. 17 refs., 8 figs., 2 tabs.

Goldstein, J.C.; McVey, B.D.; Elliott, C.J.

1987-01-01

425

Inducing quantum coherence via decays and incoherent pumping with application to population trapping, lasing without inversion, and quenching of spontaneous emission  

SciTech Connect

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)].

Kozlov, Victor V. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Fock Institute of Physics, St. Petersburg University, Ulyanovskaya 1, St. Petersburg, 198904 (Russian Federation); Rostovtsev, Yuri [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Scully, Marlan O. [Institute for Quantum Studies and Department of Physics, Texas A and M University, College Station, Texas 77843 (United States); Applied Physics and Material Science Group, Engineering Quad, Princeton University, Princeton, New Jersey 08544 (United States); Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748, Garching (Germany)

2006-12-15

426

Transform-limited x-ray pulse generation from a high-brightness self-amplified spontaneous-emission free-electron laser.  

PubMed

A method to achieve high-brightness self-amplified spontaneous emission (HB-SASE) in the free-electron laser (FEL) is described. The method uses repeated nonequal electron beam delays to delocalize the collective FEL interaction and break the radiation coherence length dependence on the FEL cooperation length. The method requires no external seeding or photon optics and so is applicable at any wavelength or repetition rate. It is demonstrated, using linear theory and numerical simulations, that the radiation coherence length can be increased by approximately 2 orders of magnitude over SASE with a corresponding increase in spectral brightness. Examples are shown of HB-SASE generating transform-limited FEL pulses in the soft x-ray and near transform-limited pulses in the hard x-ray. Such pulses may greatly benefit existing applications and may also open up new areas of scientific research. PMID:23581327

McNeil, B W J; Thompson, N R; Dunning, D J

2013-03-26

427

Amplified spontaneous emission in polymethyl methacrylate doped with 3-(1,1-dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (DCNP)  

NASA Astrophysics Data System (ADS)

Luminescence and amplified spontaneous emission (ASE) phenomenon of 3-(1,1-dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (DCNP) dissolved in a polymethyl methacrylate (PMMA) matrix have been studied. We analyzed luminescence from thin films of DCNP-PMMA excited by the neodymium doped yttrium aluminum garnet (Nd:YAG) nanosecond pulsed laser doubled and tripled in frequency. We report on ASE in function of different excitation pulse energy densities (ASE threshold was estimated to be 10 and 13 mJ/cm 2 for pumping beams wavelengths of 532 and 355 nm, respectively). We observed the photo-degradation process of a dye and performed exponential gain coefficient measurements (up to 10 cm -1) in the system.

Sznitko, L.; Mysliwiec, J.; Parafiniuk, K.; Szukalski, A.; Palewska, K.; Bartkiewicz, S.; Miniewicz, A.

2011-08-01

428

The extension of gain spectra and accurate determination of the quasi-Fermi-level separation from measured amplified spontaneous emission spectra  

NASA Astrophysics Data System (ADS)

A method for obtaining the gain spectra of semiconductor lasers in an extended energy range from amplified spontaneous emission (ASE) spectra is presented. Hakki-Paoli gain measurement is first used to determine the quasi-Fermi-level separation. By using the fitting process proposed, a self-consistent correction in determining quasi-Fermi separation leads to a reduced error (<1 meV) and a recalibration of the intrinsic absorption coefficient is also self-consistently possible. Subsequently, with measured gain in a restricted energy range, we can obtain gain spectra in a much wider energy range by our proposed algorithm in conjunction with ASE data. The application of this method in obtaining the extended gain spectra of a double-quantum-well GaInP ridge waveguide laser is demonstrated.

Fu, Liwei; Wu, Linzhang; Schweizer, Heinz

1999-11-01

429

Suitability of nanodiamond nitrogen-vacancy centers for spontaneous emission control experiments  

NASA Astrophysics Data System (ADS)

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.

Mohtashami, Abbas; Femius Koenderink, A.

2013-04-01

430

40 CFR 270.315 - What air emissions control information must I keep at my facility?  

Code of Federal Regulations, 2013 CFR

...What air emissions control information must I keep at my facility...RCRA Standardized Permits for Storage and Treatment Units Information That Must Be Kept at Your...What air emissions control information must I keep at my...

2013-07-01

431

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...

432

Gamma Ray Multiplicity Comparison of a 2-Neutron and a 4-Neutron Emission ^252Cf Spontaneous Fission  

NASA Astrophysics Data System (ADS)

The correlation between ?-ray multiplicity and neutron multiplicity in the fission process is not currently well known. Competing theories predict opposite correlations and experiments have measured only average properties. We have measured the ?-ray multiplicity spectrum of ^252Cf spontaneous fission using the LiBerACE array, comprised of six high-purity germanium (HPGe) Clover detectors, each surrounded by 16 bismuth-germanate (BGO) detectors. The Clovers were arranged in a cubic pattern around a 1 ?Ci ^252Cf source. Neutron multiplicity was determined for two cases by identifying known correlated fission products from prompt ?-rays observed in the HPGe detectors. No difference in the ?-ray multiplicity spectrum was observed for fissions that produced ^106Mo/^144Ba (2 neutrons) compared to those producing ^106Mo/^142Ba (4 neutrons).

Bleuel, D. L.; Bernstein, L. A.; Burke, J. T.; Heffner, M. D.; Norman, E. B.; Scielzo, N. D.; Sheets, S. A.; Snyderman, N. J.; Stoyer, M. A.; Wiedeking, M.; Gibelin, J.; Phair, L. W.; Mintz, J.

2008-10-01

433

The processivity factor ? controls DNA polymerase IV traffic during spontaneous mutagenesis and translesion synthesis in vivo  

PubMed Central

The dinB-encoded DNA polymerase IV (Pol IV) belongs to the recently identified Y-family of DNA polymerases. Like other members of this family, Pol IV is involved in translesion synthesis and mutagenesis. Here, we show that the C-terminal five amino acids of Pol IV are essential in targeting it to the ?-clamp, the processivity factor of the replicative DNA polymerase (Pol III) of Escherichia coli. In vivo, the disruption of this interaction obliterates the function of Pol IV in both spontaneous and induced mutagenesis. These results point to the pivotal role of the processivity clamp during DNA polymerase trafficking in the vicinity of damaged-template DNA.

Lenne-Samuel, Nathalie; Wagner, Jerome; Etienne, Helene; Fuchs, Robert P. P.

2002-01-01

434

Technology for CO{sub 2} emission monitoring and control  

SciTech Connect

The authors examined three specific areas relative to CO{sub 2} emissions and controls: (1) the effect of deregulation of the utility industry on emissions, (2) the role of advanced power systems in reducing emissions, and (3) developing CO{sub 2} mitigation technologies. In this work the Energy Technologies program office at Los Alamos attempted to initiate an integrated approach that includes a range of tasks involving both point and distributed CO{sub 2} control. The authors have examined evolving mitigation (separation and sequestration) technologies for CO{sub 2} disposal. The separation of hydrogen gas from high-temperature CO{sub 2}-containing streams is a critical component of carbon dioxide mitigation technology, and cost-effective point sequestration will require separation of CO{sub 2} from H{sub 2}. They investigated four types of separation techniques: two high-temperature membrane technologies, an intermediate-temperature membrane technology, and a separation technology based on the formation of CO{sub 2} hydrate compounds through reaction of CO{sub 2} with water at near freezing conditions. At Los Alamos, sequestration technologies are being developed along three principal areas: mineral sequestration of CO{sub 2}, the enhancement of natural sinks using biotechnology methods, and the conversion of CO{sub 2} to methanol using high-temperature photolysis.

Joyce, E.L. Jr.; Unkefer, P.J.; Pendergrass, J.H.; Parkinson, W.J.; Loose, V.W.; Brainard, J.R.

1998-12-31

435

Exhaust emission control through a hydrogen peroxide fuel augmentation system  

SciTech Connect

A system for improving efficiency and reducing harmful emissions in an internal combustion engine and for allowing the engine to run in oxygen poor environments. An oxidant, such as hydrogen peroxide, is introduced into the induction air stream of the engine. A controller senses the temperature and oxygen level in the exhaust stream of the engine and operates a valve to vary the amount of oxidant introduced to maintain maximum efficiency and minimum emissions. The oxidant provides for near stoichiometric combustion to reduce combustion products and reduce the engine`s air requirements. The reduced air requirements allow for operation of the engine in oxygen poor environments, such as operation at high altitudes. Water is added to the oxidant to cool the stoichiometric combustion temperature to prevent excessive engine wear and to further block the formation of oxides of nitrogen.

Duva, A.W.

1996-06-24

436

POEM-PM: an emission model for secondary pollution control scenarios  

Microsoft Academic Search

The paper describes the POEM-PM (POllutant Emission Model for gas and Particulate Matter) emission model design. The model, providing actual and alternative emission scenarios, represents a decision support tool to evaluate emission control strategy effectiveness. It estimates emissions at local and mesoscale level and implements a combined top-down and bottom-up approach. The POEM-PM emission fields answer the GAMES (Gas Aerosol

Claudio Carnevale; Veronica Gabusi; Marialuisa Volta

2006-01-01

437

Control of the emission channels energy flow in a nonlinear laser-potassium atom interaction  

NASA Astrophysics Data System (ADS)

A numerical study of the emissions of a four-level potassium atom excited either by a single pulse or by a pair of temporally separated pulses is presented. For a low-intensity single-pulse two-photon excitation (|4S1/2>?|6S1/2>), parametric emissions along path-1 (|6S1/2>?|5P3/2>?|4S1/2>) are generated while along path-2 (|6S1/2>?|4P3/2>?|4S1/2>) are essentially inactive. But for high single-pulse excitation, the path-1 emissions saturate and delayed path-2 amplified spontaneous emissions appear. It is shown that in the case of a double-pulse excitation scheme, proper temporal separation of the pulses and saturation of path-1 emissions caused by the first pulse can be applied to selectively transfer the excitation energy from path-1 to path-2 emissions.

Pentaris, D.; Efthimiopoulos, T.; Merlemis, N.; Lyras, A.

2012-10-01

438

Temperature characteristics of spontaneous emission and optical gain in blue InGaN/GaN quantum well structures  

NASA Astrophysics Data System (ADS)

Temperature characteristics of the light emission in blue InGaN/GaN quantum well (QW) structures were investigated using the multiband effective mass theory. The light emission intensity decreases gradually with increasing temperature because of the reduction in the optical matrix element due to the decrease in the potential well depth. On the other hand, the spillover is shown to be negligible in the investigated range of temperature and the T0 value of about 255 K is obtained. The radiative recombination coefficient Beff decreases from 0.3 × to 0.2×10-4 cm6/s at the sheet carrier density of 5×1012 cm-2 when changing from 300 to 400 K. As a result, the internal efficiency is reduced with increasing temperature because of the reduction in the radiative recombination rate.

Park, Seoung-Hwan; Moon, Yong-Tae

2013-08-01

439

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...

440

Stark interaction of identical particles with the vacuum electromagnetic field as quantum Poisson process suppressing collective spontaneous emission  

SciTech Connect

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.

Basharov, A. M. [RRC ''Kurchatov Institute'', Moscow (Russian Federation)

2011-07-15

441

Effect of a fuel additive on emission control systems  

SciTech Connect

Ethyl has conducted extensive fleet testing to investigate the effect of a manganese-based anti-knock additive (MMT) on exhaust emissions from production cars. The fleet consisted of 48 cars - six cars each of eight models representing more than 50% of 1988 U.S. sales. Three of each model were tested for 75,000 miles using the base fuel. The other three used the base fuel plus 0.03125 gram manganese per gallon as MMT. Results of this testing provided in this book, show that use of the additive will not cause or contribute to the failure of emission control systems. Exhaust back pressure data for the 48-car fleet as well as a test of a close-coupled catalyst at 80 mph showed no indication of catalyst distress or plugging. Catalyst conversion efficiency was generally higher for units aged on the MMT fuel. Particulate emission data showed that less than 0.5% of the input manganese was exhausted as airborne for the FTP cycle.

Lenane, D.L.

1990-01-01

442

Greenhouse-Gas Emission Controls and International Carbon Leakage through Trade Liberalization  

Microsoft Academic Search

This paper studies greenhouse-gas (GHG) emission controls in the presence of carbon leakage through international firm relocation. The Kyoto Protocol requires developed countries to reduce GHG emissions by a certain amount. Comparing emission quotas with emission taxes, we show that taxes coupled with lower trade costs facilitate more firm relocations than quotas do, causing more international carbon leakage. Thus, if

ISHIKAWA Jota; OKUBO Toshihiro

2009-01-01

443

[Study on foreign regulations and standards of stationary sources VOCs emission control].  

PubMed

By investigating volatile organic compounds (VOCs) emission control regulations and standards of the United States, the European Union and Japan, the suggestions on VOCs emission control and standards formulating in China were presented. Referencing foreign successful environmental management approach and experience, as well as the corresponding regulations and standards, the author believed that China can find a simple and highly effective way for controlling VOCs, through establishing the emission standards system, innovating VOCs emission control approach, improving VOCs emission control efficiency and unifying VOCs monitoring methods. PMID:22468509

Zhang, Guo-Ning; Hao, Zheng-Ping; Jiang, Mei; Wang, Hai-Lin

2011-12-01

444

Ternary ? and triton emission in the spontaneous fission of 244Cm, 246Cm and 248Cm and in the neutron induced fission of 243Cm, 245Cm and 247Cm  

NASA Astrophysics Data System (ADS)

The emission probabilities and the energy distributions of tritons and ? particles emitted in the spontaneous ternary fission (zero excitation energy) of 244Cm, 246Cm and 248Cm and in the cold neutron induced fission (excitation energy ?6.5 MeV) of 243Cm, 245Cm and 247Cm are determined. The particle identification was done with suited ?E-E telescope detectors, at the IRMM (Geel, Belgium) for the spontaneous fission and at the ILL (Grenoble, France) for the neutron induced fission measurements. Hence particle emission characteristics of the fissioning systems 244Cm, 246Cm and 248Cm are obtained at zero excitation energy and at an excitation energy around 6.5 MeV. Whilst the triton emission probability is hardly influenced by the excitation energy, the 4He emission probability in spontaneous fission is about 20% higher than for neutron induced fission. This could be explained by the influence of the cluster preformation probability on the ternary ? emission.

Vermote, S.; Wagemans, C.; Serot, O.; Heyse, J.; van Gils, J.; Soldner, T.; Geltenbort, P.

2008-06-01

445

CONTROL OF TRACE METAL EMISSIONS DURING COAL COMBUSTION  

SciTech Connect

Emissions of toxic trace metals in the form of metal fumes or submicron particulates from a coal-fired combustion source have received greater environmental and regulatory concern over the past years. Current practice of controlling these emissions is to collect them at the cold-end of the process by air-pollution control devices (APCDs) such as electrostatic precipitators and baghouses. However, trace metal fumes may not always be effectively collected by these devices because the formed fumes are extremely small. The proposed research is to explore the opportunities for improved control of toxic trace metal emissions, alternatively, at the hot-end of the coal combustion process, i.e., in the combustion chamber. The technology proposed is to prevent the metal fumes from forming during the process, which would effectively eliminate the metal emission problems. Specifically, the technology is to employ suitable sorbents to (1) reduce the amount of metal volatilization during combustion and (2) capture volatilized metal vapors. The objectives of the project are to demonstrate the technology and to characterize the metal capture process during coal combustion in a fluidized bed combustor. This final technical report details the work performed, the conclusions obtained, and the accomplishments achieved over the project performance period from July 1, 1994 through December 31, 1997. Specifically, this report consists of the following five chapters: Chapter 1. Executive Summary; Chapter 2. Metal Capture by Various Sorbents; Chapter 3. Simultaneous Metal and Sulfur Capture; Chapter 4. Sorption and Desorption of Mercury on Sorbents; and Chapter 5. Project Conclusions. In summary, the metals involved in the project were arsenic, cadmium, chromium, lead, mercury and selenium and the sorbents tested included bauxite, zeolite and calcined limestone. The three sorbents have been found to have various degree of metal capture capability on arsenic, cadmium, chromium and lead. Among them, calcined limestone is capable of simultaneouely capturing metals and sulfur. Mercury and selenium, however, can not be effectively retained by these sorbents under the combustion conditions. Mercury adsorption by sorbents at low temperatures was also investigated and the developed mass transfer model for mercury absorption appears to describe reasonably well the experimental results. Overall, the project has generated 18 presentations and/or publications in professional conferences and journals.

THOMAS C. HO

1998-02-18

446

Environmental factors controlling methane emissions for peatlands in Northern Minnesota  

SciTech Connect

Controls on methane emission from peatlands in northern Minnesota were investigated by correlation to environmental variables and by field manipulations. From September 1988 through September 1990, methane flux measurements were made at weekly to monthly intervals at six sites in the Marcell Experimental Forest, northern Minnesota (two open bog sites, two forested bog sites, a poor fen, and a fen lagg). Flux was related to water table position and peat temperature with simple correlations at individual sites and multiple regression on all sites together. The effect of water table was also investigated experimentally in {open_quotes}bog corrals{close_quotes} (open-ended metal enclosures set in the peat) in which water table was artificially raised to the surface in the driest peatland. Temperature largely controlled variation in flux within individual ecosystems at Marcell, but hydrology distinguished between-site variation. Water table position, peat temperature, and degree of peat humification explained 91% of the variance in log CH{sub 4} flux, predicted annual methane emission from individual wetlands successfully, and predicted the change in flux due to the water table manipulation. Raising the water table in the bog corrals by an average of 6 cm in autumn 1989 and 10 cm in summer 1990 increased emission by 2.5x and 2.2x, respectively. Just as expanding the scale of investigation from a single habitat in a wetland to several wetlands necessitates incorporation of additional variables to explain flux (water table, peat characteristics), modeling flux from several wetland regions, if possible, will require the addition of climate parameters. 30 refs., 8 figs., 21 tabs.

Dise, N.B.; Gorham, E. [Univ. of Minnesota, Minneapolis, MN (United States); Verry, E.S. [Forest Service, Grand Rapids, MN (United States)

1993-06-20

447

CONTROL OF CENTER-OF-MASS MOTION STATE THROUGH CUING AND DECOUPLING OF SPONTANEOUS GAIT PARAMETERS IN LEVEL WALKING  

PubMed Central

Can the center of mass (COM) motion state, i.e., its position and velocity relative to the base of support (BOS), which dictate gait stability, be predictably controlled by the global gait parameters of step length and gait speed, or by extension, cadence? The precise relationships among step length and gait speed, and the COM motion state are unknown, partially due to the interdependence between step length and gait speed and the difficulty in independent control of both parameters during spontaneous level walking. The purposes of this study were to utilize simultaneous audio-visual cuing to independently manipulate step length and gait speed, and to determine the extent to which the COM position and velocity can be subsequently controlled. Fifty-six young adults trained at one of three gait patterns in which both the step length and gait speed were targeted simultaneously. The results showed that the cuing could successfully “decouple” gait speed from step length. Although this approach did yield reliable control of the COM velocity through manipulation of gait speed (R2 = 0.97), the manipulation of step length yielded less precise control of COM position (R2 = 0.60). This latter control appears to require manipulation of an additional degree of freedom at the local segment level, such that the inclusion of trunk inclination with step length improved the prediction of COM position (R2 =0.80).

Espy, D. D.; Yang, F.; Pai, Y.-C.

2010-01-01

448

Chronic baroreflex activation restores spontaneous baroreflex control and variability of heart rate in obesity-induced hypertension.  

PubMed

The sensitivity of baroreflex control of heart rate is depressed in subjects with obesity hypertension, which increases the risk for cardiac arrhythmias. The mechanisms are not fully known, and there are no therapies to improve this dysfunction. To determine the cardiovascular dynamic effects of progressive increases in body weight leading to obesity and hypertension in dogs fed a high-fat diet, 24-h continuous recordings of spontaneous fluctuations in blood pressure and heart rate were analyzed in the time and frequency domains. Furthermore, we investigated whether autonomic mechanisms stimulated by chronic baroreflex activation and renal denervation-current therapies in patients with resistant hypertension, who are commonly obese-restore cardiovascular dynamic control. Increases in body weight to ?150% of control led to a gradual increase in mean arterial pressure to 17 ± 3 mmHg above control (100 ± 2 mmHg) after 4 wk on the high-fat diet. In contrast to the gradual increase in arterial pressure, tachycardia, attenuated chronotropic baroreflex responses, and reduced heart rate variability were manifest within 1-4 days on high-fat intake, reaching 130 ± 4 beats per minute (bpm) (control = 86 ± 3 bpm) and ?45% and <20%, respectively, of control levels. Subsequently, both baroreflex activation and renal denervation abolished the hypertension. However, only baroreflex activation effectively attenuated the tachycardia and restored cardiac baroreflex sensitivity and heart rate variability. These findings suggest that baroreflex activation therapy may reduce the risk factors for cardiac arrhythmias as well as lower arterial pressure. PMID:23913707

Iliescu, Radu; Tudorancea, Ionut; Irwin, Eric D; Lohmeier, Thomas E

2013-08-02

449

Development and evaluation of an emissions control decision aid  

NASA Astrophysics Data System (ADS)

The DSA emissions control decision aid assists with the design and evaluation of mission control plans. As part of the Office of Naval Research operational decision aiding program, the aid was formally evaluated in tests conducted by an independent ONR consultant. This report describes modifications to the aid, preparation of user's manuals for test subjects, and development of scenarios for the test program. Aid improvements occurred primarily in response to suggestions during briefings, and suggest general principles of display design. The process for scenario development described here insured a set of test scenarios appropriate for an evaluation program. The user's manuals, included in the appendices describe how to use the aid to prepare EMCON plans.

Noble, D. F.; Pugh, G. F.; Densmore, J. E., Jr.; Nunenkamp, M. T.

1980-07-01

450

Controlling mercury emissions from coal-fired power plants  

SciTech Connect

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.

Chang, R. [Electric Power Research Institute, Palo Alto, CA (United States)

2009-07-15

451

Automated Boiler Combustion Controls for Emission Reduction and Efficiency Improvement  

SciTech Connect

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.

None

1998-12-02

452

Emission analysis & solution of control panel of elevator : A case study  

Microsoft Academic Search

EMC testing of products are essential requirement for export to Europe. This requirement covers emission as well as immunity testing. Compliance to emission requirement needs emission below to the limit line of a product specification. Compliance can be achieved by using better design practices & retrofit practices after the design of product. Control panel of elevator control the activities of

S. Chand; A. Sathyanarayanan

2006-01-01

453

Control of blowby emissions and lubricating oil consumption in I.C. engines  

Microsoft Academic Search

Blowby emissions contribute a significant part of total hydrocarbon emission by an automobile, but no effort has so far been made in our country to control the same. The diesel engineers have, so far, neglected investigations in this field and the literature available on blowby emissions investigation is very scarce. This paper deals with investigations on the control of blowby

H. C. Dhariwal

1997-01-01

454

Optical properties of the breast during spontaneous and birth control pill-mediated menstrual cycles.  

PubMed

Mastodynia is correlated with the menstrual cycle. Using frequency-domain near-infrared spectroscopy (FD-NIRS), we investigated changes in breast perfusion in women who were or were not using hormonal contraception. Healthy volunteers, on or not on hormonal contraception, were examined. Optical properties were measured in all quadrants of both breasts, and physiological parameters were calculated. Measurements were repeated every other day during one complete menstrual cycle. Measurements were comparable in all quadrants. Data remained unchanged during the entire cycle in patients using hormonal contraception. However, a biphasic variation of deoxyhemoglobin, oxyhemoglobin, total hemoglobin (tHb), and water content (H(2)O) was observed in women not using contraception. tHb and H(2)O distinctly increased during the ovulation period and remained elevated throughout the luteal phase. It was concluded that FD-NIRS allows accurate measurement of optical properties of human breasts. As opposed to the menstrual cycles of persons using oral contraception, spontaneous menstrual cycles exhibit biphasic variations of tissue perfusion parameters. These findings are important for the investigation of mastodynia. PMID:19291352

Stahel, Michèle C; Wolf, Martin; Baños, Ana; Hornung, R

2009-03-17

455

Chronic ?-adrenoceptor antagonist treatment controls cardiovascular remodeling in heart failure in the aging spontaneously hypertensive rat.  

PubMed

Selective ?1-adrenoceptor antagonists are part of standard therapy to prolong survival in human heart failure. This study has measured structural, functional, and electrical changes in the cardiovascular system of aging male spontaneously hypertensive rats (SHRs) to determine whether ?1-adrenoceptor antagonist treatment can prevent or reverse the development of cardiovascular remodeling and heart failure in these rats. Fifteen-month-old male Wistar-Kyoto (WKY) rats or SHRs were treated with increasing metoprolol doses (30 mg·kg·d for 4 weeks, then 50 mg·kg·d for 4 weeks, then 80 mg·kg·d for 16 weeks po). Cardiovascular structure and function were determined using organ wet weight, in vivo echocardiography, histological analysis of inflammation and collagen, isolated heart and thoracic aortic ring preparations, and single cell microelectrode measurements. From 15 months, untreated SHRs developed left ventricular dilation, hypertrophy, inflammatory cell infiltration and fibrosis, and action potential prolongation together with progressive systolic, diastolic, and endothelial dysfunction and increased cardiac stiffness. Treatment with metoprolol decreased systolic blood pressure at 21 months only but improved survival, decreased ventricular weight, prevented chamber dilation, reduced inflammation, decreased fibrosis, attenuated action potential prolongation, improved systolic and diastolic function, decreased stiffness and improved endothelium-independent vascular responses. Chronic metoprolol treatment markedly attenuated both cardiac and vascular remodeling in the aging SHRs, thus attenuating the onset of heart failure and improving survival, independent of blood pressure reduction. PMID:21709583

Chan, Vincent; Fenning, Andrew; Hoey, Andrew; Brown, Lindsay

2011-10-01

456

LANDFILL OPERATION FOR CARBON SEQUESTRATION AND MAXIMUM METHANE EMISSION CONTROL  

SciTech Connect

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.

Don Augenstein; Ramin Yazdani; Rick Moore; Michelle Byars; Jeff Kieffer; Professor Morton Barlaz; Rinav Mehta

2000-02-26