WorldWideScience

Sample records for spontaneous four-wave mixing

  1. Frequency conversion through spontaneous degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Olausson, Christina Bjarnal Thulin

    2014-01-01

    Frequency conversion through spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers. Different FWM processes are observed, phasematching between fiber modes of orthogonal polarization, intermodal phasematching across bandgaps, and intramoda...... phasematching within the same transmission band as the one containing the pump laser. Furthermore first and second order Raman scattering is observed. The interplay between the different FWM processes and Raman scattering are investigated....

  2. Optimisation of spontaneous four-wave mixing in a ring microcavity

    Science.gov (United States)

    Chuprina, I. N.; An, P. P.; Zubkova, E. G.; Kovalyuk, V. V.; Kalachev, A. A.; Gol’tsman, G. N.

    2017-11-01

    A theory of spontaneous four-wave mixing in a ring microcavity is developed. The rate of emission of biphotons for pulsed and monochromatic pumping with allowance for the dispersion of group velocities is analytically calculated. In the first case, pulses in the form of an increasing exponential are considered, which are optimal for excitation of an individual resonator mode. The behaviour of the group velocity dispersion as a function of the width and height of the waveguide is studied for a specific case of a ring microcavity made of silicon nitride. The results of the numerical calculation are in good agreement with the experimental data. The ring microcavity is made of two types of waveguides: completely etched and half etched. It is found that the latter allow for better control over the parameters in the manufacturing process, making them more predictable. Presented at the Russian – British Symposium on Quantum Technologies (Moscow, 20 – 23 March 2017)

  3. Broadband photon pair generation in green fluorescent proteins through spontaneous four-wave mixing

    Science.gov (United States)

    Shi, Siyuan; Thomas, Abu; Corzo, Neil V.; Kumar, Prem; Huang, Yuping; Lee, Kim Fook

    2016-04-01

    Recent studies in quantum biology suggest that quantum mechanics help us to explore quantum processes in biological system. Here, we demonstrate generation of photon pairs through spontaneous four-wave mixing process in naturally occurring fluorescent proteins. We develop a general empirical method for analyzing the relative strength of nonlinear optical interaction processes in five different organic fluorophores. Our results indicate that the generation of photon pairs in green fluorescent proteins is subject to less background noises than in other fluorophores, leading to a coincidence-to-accidental ratio ~145. As such proteins can be genetically engineered and fused to many biological cells, our experiment enables a new platform for quantum information processing in a biological environment such as biomimetic quantum networks and quantum sensors.

  4. Broadband photon pair generation in green fluorescent proteins through spontaneous four-wave mixing

    Science.gov (United States)

    Shi, Siyuan; Thomas, Abu; Corzo, Neil V.; Kumar, Prem; Huang, Yuping; Lee, Kim Fook

    2016-01-01

    Recent studies in quantum biology suggest that quantum mechanics help us to explore quantum processes in biological system. Here, we demonstrate generation of photon pairs through spontaneous four-wave mixing process in naturally occurring fluorescent proteins. We develop a general empirical method for analyzing the relative strength of nonlinear optical interaction processes in five different organic fluorophores. Our results indicate that the generation of photon pairs in green fluorescent proteins is subject to less background noises than in other fluorophores, leading to a coincidence-to-accidental ratio ~145. As such proteins can be genetically engineered and fused to many biological cells, our experiment enables a new platform for quantum information processing in a biological environment such as biomimetic quantum networks and quantum sensors. PMID:27076032

  5. Stimulated and spontaneous four-wave mixing in silicon-on-insulator coupled photonic wire nano-cavities

    OpenAIRE

    Azzini, Stefano; Grassani, Davide; Galli, Matteo; Gerace, Dario; Patrini, Maddalena; Liscidini, Marco; Velha, Philippe; Bajoni, Daniele

    2013-01-01

    We report on four-wave mixing in coupled photonic crystal nano-cavities on a silicon-on-insulator platform. Three photonic wire cavities are side-coupled to obtain three modes equally separated in energy. The structure is designed to be self-filtering, and we show that the pump is rejected by almost two orders of magnitudes. We study both the stimulated and the spontaneous four-wave mixing processes: owing to the small modal volume, we find that signal and idler photons are generated with a h...

  6. Stimulated and spontaneous four-wave mixing in silicon-on-insulator coupled photonic wire nano-cavities

    Science.gov (United States)

    Azzini, Stefano; Grassani, Davide; Galli, Matteo; Gerace, Dario; Patrini, Maddalena; Liscidini, Marco; Velha, Philippe; Bajoni, Daniele

    2013-07-01

    We report on four-wave mixing in coupled photonic crystal nano-cavities on a silicon-on-insulator platform. Three photonic wire cavities are side-coupled to obtain three modes equally separated in energy. The structure is designed to be self-filtering, and we show that the pump is rejected by almost two orders of magnitude. We study both the stimulated and the spontaneous four-wave mixing processes: owing to the small modal volume, we find that signal and idler photons are generated with a hundred-fold increase in efficiency as compared to silicon micro-ring resonators.

  7. Counter-propagating spontaneous four wave mixing: photon-pair factorability and ultra-narrowband single photons

    Science.gov (United States)

    Monroy-Ruz, Jorge; Garay-Palmett, Karina; U'Ren, Alfred B.

    2016-10-01

    We introduce a new kind of spontaneous four wave mixing process for the generation of photon pairs, in which the four waves involved counter-propagate in a guided-wave {χ }(3) medium; we refer to this process as counter-propagating spontaneous four wave mixing (CP-SFWM). We show that for the simplest CP-SFWM source, in which all waves propagate in the same polarization and transverse mode and in which self- and cross-phase modulation effects are negligible, phasematching is attained automatically regardless of dispersion in the fiber or waveguide. Furthermore, we show that in two distinct versions of this source (both pumps pulsed, or one pump pulsed and the remaining one monochromatic), the two-photon state is automatically factorable provided that the length of the nonlinear medium exceeds a certain threshold, easily achievable in practice since this threshold length tends to be in the range of mm to cm. We also show that if one of the pumps approaches the monochromatic limit, and for a sufficient nonlinear medium length, the bandwidth of one of the two photons in a given pair may be reduced to the level of MHz, compatible with electronic transitions for the implementation of atom-photon interfaces, without the use of optical cavities.

  8. Spectrally pure heralded single photons by spontaneous four-wave mixing in a fiber: reducing impact of dispersion fluctuations

    DEFF Research Database (Denmark)

    Koefoed, Jacob Gade; Friis, Søren Michael Mørk; Christensen, Jesper Bjerge

    2017-01-01

    We model the spectral quantum-mechanical purity of heralded single photons from a photon-pair source based on nondegenerate spontaneous four-wave mixing taking the impact of distributed dispersion fluctuations into account. The considered photon-pair-generation scheme utilizes pump-pulse walk......-off to produce pure heralded photons and phase matching is achieved through the dispersion properties of distinct spatial modes in a few-mode silica step-index fiber. We show that fiber-core-radius fluctuations in general severely impact the single-photon purity. Furthermore, by optimizing the fiber design we...... show that generation of single photons with very high spectral purity is feasible even in the presence of large core-radius fluctuations. At the same time, contamination from spontaneous Raman scattering is greatly mitigated by separating the single-photon frequency by more than 32 THz from the pump...

  9. Generation of pure heralded single-photon states by cross-polarized spontaneous four-wave mixing

    DEFF Research Database (Denmark)

    Christensen, Jesper Bjerge; McKinstrie, Colin J.; Rottwitt, Karsten

    2016-01-01

    We propose a novel scheme which employs cross-polarized pumps to generate temporally and spectrally uncorrelated signal-idler photon-pairs through spontaneous fourwave mixing in a birefringent third-order nonlinear waveguide.......We propose a novel scheme which employs cross-polarized pumps to generate temporally and spectrally uncorrelated signal-idler photon-pairs through spontaneous fourwave mixing in a birefringent third-order nonlinear waveguide....

  10. Diffraction manipulation by four-wave mixing.

    Science.gov (United States)

    Katzir, Itay; Ron, Amiram; Firstenberg, Ofer

    2015-03-09

    We suggest a scheme to manipulate paraxial diffraction by utilizing the dependency of a four-wave mixing process on the relative angle between the light fields. A microscopic model for four-wave mixing in a Λ-type level structure is introduced and compared to recent experimental data. We show that images with feature size as low as 10 μm can propagate with very little or even negative diffraction. The mechanism is completely different from that conserving the shape of spatial solitons in nonlinear media, as here diffraction is suppressed for arbitrary spatial profiles. At the same time, the gain inherent to the nonlinear process prevents loss and allows for operating at high optical depths. Our scheme does not rely on atomic motion and is thus applicable to both gaseous and solid media.

  11. Four-wave mixing with femtosecond pulses

    Energy Technology Data Exchange (ETDEWEB)

    Skenderovic, H [Institute of Physics, Bijenicka cesta 46, HR-10001 Zagreb (Croatia)], E-mail: hrvoje@ifs.hr

    2009-07-15

    The recent development of noncollinear optical parametric amplifiers (NOPAs) has equipped many laboratories with widely tunable, spectrally broad ultrashort laser pulses with a duration of 15-30 fs. The present work deals with sub-20 fs pulsed degenerate four wave mixing (DFWM) on high-frequency vibrational levels in all-trans-{beta}-carotene. The observed wavepacket motion on the electronic ground state revealed fast oscillating vibrational modes whose frequencies and time development were measured. The coherent control in an open loop is demonstrated by appropriate phase shaping of the pulses.

  12. Four Wave Mixing using Intermodal Nonlinearities

    DEFF Research Database (Denmark)

    Rishøj, Lars Søgaard

    The nonlinear process of four-wave mixing (FWM) enables coupling of energy between wavelengths. This is useful for both optical amplification and wavelength conversion. A crucial prerequisite for the process is phase matching. This PhD project investigates how higher order modes (HOMs) in fibers...... around 800 nm. Using pulse propagation simulations this process is investigated in details, which includes examining the impact of the overlap integrals and outer diameter (OD) variations along the fiber. Experimentally, it is demonstrated that using a long period grating (LPG), it is possible to convert...... 99.8 % of the power from the fundamental mode to a specific HOM in the custom designed fiber. Furthermore, it is demonstrated that stable propagation in the considered fiber is possible, without deterioration from mode coupling. Finally, modulation instability and multiple FWM signal and idler lines...

  13. Generation of two-temporal-mode photon states by vector four-wave mixing

    DEFF Research Database (Denmark)

    Mckinstrie, C. J.; Christensen, J. B.; Rottwitt, Karsten

    2017-01-01

    Photon pair states and multiple-photon squeezed states have many applications in quantum information science. In this paper, Green functions are derived for spontaneous four-wave mixing in the low-and high-gain regimes. Nondegenerate four-wave mixing in a strongly-birefringent medium generates...

  14. Polarization switch of four-wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Olausson, Christina Bjarnal Thulin

    2015-01-01

    Degenerate spontaneous four-wave mixing is considered in a large mode area hybrid photonic crystal fiber. Numerical and experimental results show birefringence assisted four-wave mixing for a certain polarization state of the pump field. The parametric gain can be turned on and off by switching...... the polarization state of the pump field between the two principal axis of the hybrid photonic crystal fiber. (C) 2015 Optical Society of America...

  15. Optical solitons with DWDM technology and four-wave mixing

    Science.gov (United States)

    Ekici, Mehmet; Zhou, Qin; Sonmezoglu, Abdullah; Moshokoa, Seithuti P.; Ullah, Malik Zaka; Biswas, Anjan; Belic, Milivoj

    2017-07-01

    This paper obtains bright and singular optical soliton solutions to DWDM system in presence of four-wave mixing. The extended trial function scheme is adopted. The two types of nonlinear media studied are Kerr law and parabolic law. There are other types of waves that appears as a byproduct to this scheme.

  16. Continuum contribution to excitonic four-wave mixing

    DEFF Research Database (Denmark)

    Birkedal, Dan; Sayed, Karim El; Vadim, Lyssenko

    1996-01-01

    Summary form only given. We present an experimental and theoretical investigation of ultrafast transient four-wave mixing (TFWM) of GaAs-AlGaAs quantum wells for simultaneous excitation of exciton and continuum states. Recent TFWM experiments on semiconductors have shown unexpected results when b...

  17. Temporally uncorrelated photon-pair generation by dual-pump four-wave mixing

    DEFF Research Database (Denmark)

    Christensen, Jesper Bjerge; McKinstrie, C. J.; Rottwitt, Karsten

    2016-01-01

    We study the preparation of heralded single-photon states using dual-pump spontaneous four-wave mixing. The dual-pump configuration, which in our case employs cross-polarized pumps, allows for a gradual variation of the nonlinear interaction strength enabled by a birefringence-induced walk-off be...

  18. Generation of two-temporal-mode photon states by vector four-wave mixing.

    Science.gov (United States)

    McKinstrie, C J; Christensen, J B; Rottwitt, K; Raymer, M G

    2017-08-21

    Photon pair states and multiple-photon squeezed states have many applications in quantum information science. In this paper, Green functions are derived for spontaneous four-wave mixing in the low- and high-gain regimes. Nondegenerate four-wave mixing in a strongly-birefringent medium generates signal and idler photons that are associated with only one pair of temporal (Schmidt) modes, for a wide range of pump powers and arbitrary pump shapes. The Schmidt coefficients (expected photon numbers) depend sensitively on the pump powers, and the Schmidt functions (shapes of the photon wavepackets) depend sensitively on the pump powers and shapes, which can be controlled.

  19. Four-Wave Mixing Aplication in Semiconductor Optical Amplifier

    Directory of Open Access Journals (Sweden)

    Radoslav Odrobinak

    2004-01-01

    Full Text Available Four-Wave Mixing (FWM in semiconductor optical amplifiers is an attrative mechanism for wavelenght coversion in wavelenght-division multiplexed (WDM systems since it provides modulation format and bit rate transparency over wide tuning ranges. A series of systems experiments evaluating several aspects of the performance of these devices at bit rates of 2.5 and 10 Gb/s are presented.

  20. Multi-component optical azimuthons of four-wave mixing

    Science.gov (United States)

    Wang, Rui-Min; Wang, Xing-Peng; Wu, Zhen-Kun; Yao, Xin; Zhang, Yi-Qi; Zhang, Yan-Peng

    2014-05-01

    We report the multi-component optical azimuthons of four-wave mixing (FWM) composed of several modulated vortex beams, the so-called azimuthons, in V-type three-level and two-level atomic systems. We analyze the formation mechanisms of the FWM azimuthons theoretically and experimentally. In addition, we illustrate the interactions between the co-propagating azimuthon components. Finally, we also compare the stabilities of azimuthons in V-type three-level and two-level atomic systems.

  1. Coherent control of dressed images of four-wave mixing

    Science.gov (United States)

    Wu, Zhen-Kun; Zhang, Yi-Qi; Liu, Tai-Kun; Zhang, Zhao-Yang; Li, Cheng; Zhang, Yan-Peng; Xiao, Min

    2013-04-01

    In two-level as well as V-type three-level atomic systems, we study probe transmission, four-wave mixing (FWM) and fluorescence signals with dressing effect experimentally and theoretically. We find both the hyperfine structure (at the same energy level) and the transition dipole moment (at different energy levels) can affect the dressing effect. We also experimentally investigate that angle-control dynamics in the nonlinear propagation of the images of the probe and generated FWM in two-level atomic systems, and find that the focusing and defocusing of probe beam and FWM signals can be greatly affected by the angles between dressing fields.

  2. Photon-pair generation by four-wave mixing in optical fibers.

    Science.gov (United States)

    Lin, Q; Yaman, F; Agrawal, Govind P

    2006-05-01

    We present a theory to quantify a fundamental limit on correlated photon pairs generated through four-wave mixing inside optical fibers in the presence of spontaneous Raman scattering (SpRS). Our theory is able to explain current experimental data. We show that if correlated photon pairs are generated with polarization orthogonal to the pump the effect of SpRS is significantly reduced over a broad spectral region extending from 5 to 15 THz.

  3. Theoretical analysis of four wave mixing in quantum dot optical amplifiers

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Mørk, Jesper

    2003-01-01

    The four wave mixing properties of semiconductor quantum dot amplifiers have been investigated. The combination of strong non-equilibrium depletion of dot levels and a small linewidth enhancement factor results in efficient and symmetric four wave mixing.......The four wave mixing properties of semiconductor quantum dot amplifiers have been investigated. The combination of strong non-equilibrium depletion of dot levels and a small linewidth enhancement factor results in efficient and symmetric four wave mixing....

  4. Parametric Four-Wave Mixing Using a Single cw Laser

    Science.gov (United States)

    Brekke, Erik; Herman, Emily; Alderson, Laura

    2014-05-01

    We present progress in using parametric four-wave mixing in a rubidium cell for the generation of coherent emission at 420 nm and 5.4 μm. A simple system using a single external cavity diode laser at 778 nm and a tapered amplifier supplies the needed optical beams. The efficiency is limited by absorption of the 420 nm beam, with single pass outputs of 40 μW. Optical pumping presents a possibility for increased output powers, but radiation trapping must be overcome at high densities. Several methods for increasing the effectiveness of the process are currently underway. The resulting beam at 420 nm presents an intriguing alternative method of exciting Rydberg states in Rubidium atoms.

  5. Degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Lægsgaard, Jesper

    2013-01-01

    Spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers, in which photonic bandgap guidance and index guidance is combined. Calculations show the parametric gain is maximum on the edge of a photonic bandgap, for a large range of pump...... wavelengths. The FWM products are observed on the edges of a transmission band experimentally, in good agreement with the numerical results. Thereby the bandedges can be used to control the spectral positions of FWM products through a proper fiber design. The parametric gain control combined with a large mode...

  6. Saturation properties of four-wave mixing between short optical pulses in semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Mørk, Jesper; Mecozzi, A.; Diez, S.

    1999-01-01

    Summary form only given. The authors report the first comparison between theory and experiment on the four wave mixing between trains of short pulses in semiconductor optical amplifiers. The theory is able to explain all qualitative features seen in the experiment.......Summary form only given. The authors report the first comparison between theory and experiment on the four wave mixing between trains of short pulses in semiconductor optical amplifiers. The theory is able to explain all qualitative features seen in the experiment....

  7. Intermodal parametric gain of degenerate four wave mixing in large mode area hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Lægsgaard, Jesper; Alkeskjold, Thomas Tanggaard

    2013-01-01

    Intermodal degenerate four wave mixing (FWM) is investigated numerically in large mode area hybrid photonic crystal fibers. The dispersion is controlled independently of core size, and thus allows for power scaling of the FWM process.......Intermodal degenerate four wave mixing (FWM) is investigated numerically in large mode area hybrid photonic crystal fibers. The dispersion is controlled independently of core size, and thus allows for power scaling of the FWM process....

  8. Polarization Insensitive Wavelength Conversion Based on Four-Wave Mixing in a Silicon Nanowire

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Peucheret, Christophe

    2012-01-01

    We experimentally demonstrate, for the first time, polarization-insensitive wavelength conversion of a 10 Gb/s NRZ-OOK data signal based on four-wave mixing in a silicon nanowire with bit-error rate measurements.......We experimentally demonstrate, for the first time, polarization-insensitive wavelength conversion of a 10 Gb/s NRZ-OOK data signal based on four-wave mixing in a silicon nanowire with bit-error rate measurements....

  9. Effect of Particular Nonlinear Dispersion in Photorefractive Four wave Mixing on Slow and Fast Light (Preprint)

    Science.gov (United States)

    2018-01-31

    coupling strength increases. The conclusions of the theoretical analysis are confirmed experimentally for photorefractive four-wave mixing in...fast light Konstantin Shcherbin*a, Pierre Matheyb, and Dean R. Evansc aInstitute of Physics , National Academy of Sciences, Prospekt Nauki 46, 03680...conclusions of the theoretical analysis are confirmed experimentally for photorefractive four-wave mixing in barium titanate. Keywords: slow light

  10. Quantum-state-preserving Frequency Conversion Using Four-wave Mixing

    DEFF Research Database (Denmark)

    Andersen, Lasse Mejling; Reddy, Dileep V.; McKinstrie, Colin J.

    2013-01-01

    We investigate the applicability of temporal multiplexing using four-wave mixing Bragg scattering for quantum frequency conversion. Various pump shapes are considered and we find that a large selectivity is possible for all the pump shapes.......We investigate the applicability of temporal multiplexing using four-wave mixing Bragg scattering for quantum frequency conversion. Various pump shapes are considered and we find that a large selectivity is possible for all the pump shapes....

  11. [Study on phase-matching of four-wave mixing spectrum in photonic crystal fiber].

    Science.gov (United States)

    Liu, Xiao-xu; Wang, Shu-tao; Zhao, Xing-tao; Chen, Shuang; Zhou, Gui-yao; Wu, Xi-jun; Li, Shu-guang; Hou, Lan-Tian

    2014-06-01

    In the present paper, the four-wave mixing principle of fiber was analyzed, and the high-gain phase-matching conditions were shown. The nonlinear coefficient and dispersion characteristics of photonic crystal fibers were calculated by multipole method. The phase mismatch characteristics of fibers with multiple zero-dispersion wavelengths were analyzed for the first time. The changing rules of phase matching wavelength with the pump wavelength and the pump power were obtained, and the phase matching curves were shown. The characteristics of phase matching wavelengths for different dispersion curves were analyzed. There are four new excitation wavelengths of four-wave mixing spectrum in two zero-dispersion wavelength photonic crystal fiers. Four-wave mixing spectroscopy of photonic crystal fibers with two zero-dispersion wavelengths was obtained in the experi-ent, which is consistent with the theoretical analysis, and verified the reliability of the phase matching theory. The fiber with multiple zero-dispersion wavelengths can create a ricbhphase-matching topology, excite more four-wave mixing wavelengths, ena-ling enhanced control over the spectral locations of the four-wave mixing and resonant-radiation bands emitted by solitons and short pulses. These provide theoretical guidance for photonic crystal fiber wavelength conversion and supercontinoum generation based on four-wave mixing.

  12. Enhanced continuous-wave four-wave mixing efficiency in nonlinear AlGaAs waveguides.

    Science.gov (United States)

    Apiratikul, Paveen; Wathen, Jeremiah J; Porkolab, Gyorgy A; Wang, Bohan; He, Lei; Murphy, Thomas E; Richardson, Christopher J K

    2014-11-03

    Enhancements of the continuous-wave four-wave mixing conversion efficiency and bandwidth are accomplished through the application of plasma-assisted photoresist reflow to reduce the sidewall roughness of sub-square-micron-modal area waveguides. Nonlinear AlGaAs optical waveguides with a propagation loss of 0.56 dB/cm demonstrate continuous-wave four-wave mixing conversion efficiency of -7.8 dB. Narrow waveguides that are fabricated with engineered processing produce waveguides with uncoated sidewalls and anti-reflection coatings that show group velocity dispersion of +0.22 ps²/m. Waveguides that are 5-mm long demonstrate broadband four-wave mixing conversion efficiencies with a half-width 3-dB bandwidth of 63.8-nm.

  13. Schmidt decompositions of parametric processes II: vector four-wave mixing.

    Science.gov (United States)

    McKinstrie, C J; Ott, J R; Karlsson, M

    2013-05-06

    In vector four-wave mixing, one or two strong pump waves drive two weak signal and idler waves, each of which has two polarization components. In this paper, vector four-wave mixing processes in a randomly-birefringent fiber (modulation interaction, phase conjugation and Bragg scattering) are studied in detail. For each process, the Schmidt decompositions of the coupling matrices facilitate the solution of the signal-idler equations and the Schmidt decomposition of the associated transfer matrix. The results of this paper are valid for arbitrary pump polarizations.

  14. Mode-selective wavelength conversion based on four-wave mixing in a multimode silicon waveguide

    DEFF Research Database (Denmark)

    Ding, Yunhong; Xu, Jing; Ou, Haiyan

    2014-01-01

    to phase mismatch. A two-mode division multiplexing circuit with tapered directional coupler based (de)multiplexers and a multimode waveguide is designed and fabricated for this application. Experimental results show clear eye-diagrams and moderate power penalties for the wavelength conversion of both......We propose and demonstrate all-optical mode-selective wavelength conversion in a silicon waveguide. The mode-selective wavelength conversion relies on strong four-wave mixing when pump and signal light are on the same spatial mode, while weak four-wave mixing is obtained between different modes due...... modes....

  15. Resonant four-wave mixing of gold nanoparticles for three-dimensional cell microscopy.

    Science.gov (United States)

    Masia, Francesco; Langbein, Wolfgang; Watson, Peter; Borri, Paola

    2009-06-15

    By detecting the transient four-wave mixing from gold nanoparticles in resonance with their surface plasmon, we demonstrate a multiphoton imaging modality suited for cell microscopy. Four-wave mixing is measured free from background using a three-beam excitation geometry and heterodyne detection. We achieve a spatial resolution of 140 nm in-plane and 470 nm in the axial direction, surpassing the one-photon diffraction limit. With this technique, high-contrast photostable imaging of Golgi structures is demonstrated in HepG2 cells labeled with gold nanoparticles of 10 nm and 5 nm diameter.

  16. Correlation in photon pairs generated using four-wave mixing in a cold atomic ensemble

    Science.gov (United States)

    Ferdinand, Andrew Richard; Manjavacas, Alejandro; Becerra, Francisco Elohim

    2017-04-01

    Spontaneous four-wave mixing (FWM) in atomic ensembles can be used to generate narrowband entangled photon pairs at or near atomic resonances. While extensive research has been done to investigate the quantum correlations in the time and polarization of such photon pairs, the study and control of high dimensional quantum correlations contained in their spatial degrees of freedom has not been fully explored. In our work we experimentally investigate the generation of correlated light from FWM in a cold ensemble of cesium atoms as a function of the frequencies of the pump fields in the FWM process. In addition, we theoretically study the spatial correlations of the photon pairs generated in the FWM process, specifically the joint distribution of their orbital angular momentum (OAM). We investigate the width of the distribution of the OAM modes, known as the spiral bandwidth, and the purity of OAM correlations as a function of the properties of the pump fields, collected photons, and the atomic ensemble. These studies will guide experiments involving high dimensional entanglement of photons generated from this FWM process and OAM-based quantum communication with atomic ensembles. This work is supported by AFORS Grant FA9550-14-1-0300.

  17. Correlation coefficient measurement of the mode-locked laser tones using four-wave mixing.

    Science.gov (United States)

    Anthur, Aravind P; Panapakkam, Vivek; Vujicic, Vidak; Merghem, Kamel; Lelarge, Francois; Ramdane, Abderrahim; Barry, Liam P

    2016-06-01

    We use four-wave mixing to measure the correlation coefficient of comb tones in a quantum-dash mode-locked laser under passive and active locked regimes. We study the uncertainty in the measurement of the correlation coefficient of the proposed method.

  18. Theory of nondegenerate four-wave mixing between pulses in a semiconductor waveguide

    DEFF Research Database (Denmark)

    Mørk, Jesper; Mecozzi, A.

    1997-01-01

    We develop a perturbation theory for calculating the effects of saturation on nondegenerate four-wave mixing between short optical pulses in a semiconductor optical amplifier. Saturation due to ultrafast intraband dynamics like carrier heating and spectral hole burning is found to be important...

  19. 320 Gbit/s DQPSK all-optical wavelength conversion using four wave mixing

    DEFF Research Database (Denmark)

    Galili, Michael; Huettl, B.; Schmidt-Langhorst, C.

    2007-01-01

    In this paper we demonstrate wavelength conversion of 320 Gbit/s DQPSK and 160 Gbit/s DPSK data signals by four wave mixing in highly nonlinear fibre. Error free operation is shown for conversion of both DPSK and DQPSK...

  20. Integrated CARS source based on seeded four-wave mixing in silicon nitride

    NARCIS (Netherlands)

    Epping, J.P.; Kues, M.; van der Slot, Petrus J.M.; Lee, Christopher James; Fallnich, C.; Boller, Klaus J.

    2013-01-01

    We present a theoretical investigation of an integrated nonlinear light source for coherent anti-Stokes Raman scattering (CARS) based on silicon nitride waveguides. Wavelength tunable and temporally synchronized signal and idler pulses are obtained by using seeded four-wave mixing. We find that the

  1. Four-wave mixing in InAlGaAs quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Birkedal, Dan; Hvam, Jørn Märcher

    2001-01-01

    broadening strongly reduce the interaction with the electromagnetic field. Until now, four-wave mixing (FWM) in III-V quantum dots has only been reported in optical amplifiers at room temperature, where the interaction length is increased by waveguiding in the quantum dot plane. We have carried out...

  2. Mode-Selective Wavelength Conversion Based on Four-Wave Mixing in a Multimode Silicon Waveguide

    DEFF Research Database (Denmark)

    Ding, Yunhong; Xu, Jing; Ou, Haiyan

    2013-01-01

    We report all-optical mode-selective wavelength conversion based on four-wave mixing in a multimode Si waveguide. A two-mode division multiplexing circuit using tapered directional coupler based (de)multiplexers is used for the application. Experimental results show clear eye-diagrams and moderate...... power penalties for the conversion of both modes....

  3. Quantum frequency translation by four-wave mixing in a fiber: low-conversion regime

    DEFF Research Database (Denmark)

    Andersen, Lasse Mejling; McKinstrie, C. J.; Raymer, M. G.

    2012-01-01

    In this paper we consider frequency translation enabled by Bragg scattering, a four-wave mixing process. First we introduce the theoretical background of the Green function formalism and the Schmidt decomposition. Next the Green functions for the low-conversion regime are derived perturbatively...

  4. Image processing by four-wave mixing in photorefractive GaAs

    Science.gov (United States)

    Gheen, Gregory; Cheng, Li-Jen

    1987-01-01

    Three image processing experiments were performed by degenerate four-wave mixing in photorefractive GaAs. The experiments were imaging by phase conjugation, edge enhancement, and autocorrelation. The results show that undoped, semiinsulating, liquid-encapsulated Czochralski-grown GaAs crystals can be used as effective optical processing media despite their small electrooptic coefficient.

  5. Continuum contribution to excitonic four-wave mixing due to interaction-induced nonlinearities

    DEFF Research Database (Denmark)

    Birkedal, Dan; Vadim, Lyssenko; Hvam, Jørn Märcher

    1996-01-01

    We present an experimental and theoretical investigation of ultrafast transient four-wave mixing of GaAs/AlxGa1-xAs quantum wells for coherent excitation of exciton and continuum states. The signal appears at the exciton resonance and is shown to consist of two contributions: an intense spectrally...

  6. Transient four-wave mixing in T-shaped GaAs quantum wires

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Gislason, Hannes; Hvam, Jørn Märcher

    1999-01-01

    The binding energy of excitons and biexcitons and the exciton dephasing in T-shaped GaAs quantum wires is investigated by transient four-wave mixing. The T-shaped structure is fabricated by cleaved-edge overgrowth, and its geometry is engineered to optimize the one-dimensional confinement...

  7. Bit rate and pulse width dependence of four-wave mixing of short optical pulses in semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Diez, S.; Mecozzi, A.; Mørk, Jesper

    1999-01-01

    We investigate the saturation properties of four-wave mixing of short optical pulses in a semiconductor optical amplifier. By varying the gain of the optical amplifier, we find a strong dependence of both conversion efficiency and signal-to-background ratio on pulse width and bit rate....... In particular, the signal-to-background ratio can be optimized for a specific amplifier gain. This behavior, which is coherently described in experiment and theory, is attributed to the dynamics of the amplified spontaneous emission, which is the main source of noise in a semiconductor optical amplifier....

  8. Study of Raman-free photon pair generation using inter-modal four-wave mixing in a few-mode silica fiber

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Christensen, Jesper Bjerge; Koefoed, Jacob Gade

    2017-01-01

    Single-photon sources are key components in applications of photonic quantum technologies such as quantum key distribution (QKD) [1]. One way of realizing single-photon sources is generation of photon pairs (PP) using spontaneous four-wave mixing (FWM): two photons from a pump p annihilate...

  9. Detailed characterization of CW- and pulsed-pump four-wave mixing in highly nonlinear fibers

    DEFF Research Database (Denmark)

    Lillieholm, Mads; Galili, Michael; Grüner-Nielsen, L.

    2016-01-01

    We present a quantitative comparison of continuouswave- (CW) and pulsed-pump four-wave mixing (FWM) in commercially available highly nonlinear fibers (HNLFs), and suggest properties for which the CW and pulsed FWM bandwidths are limited in practice. The CWand pulsed-pump parametric gain is charac......We present a quantitative comparison of continuouswave- (CW) and pulsed-pump four-wave mixing (FWM) in commercially available highly nonlinear fibers (HNLFs), and suggest properties for which the CW and pulsed FWM bandwidths are limited in practice. The CWand pulsed-pump parametric gain...... bandwidth. However, an inverse scaling of the TOD with the dispersion fluctuations, leads to different CW-optimized fibers, which depend only on the even dispersion-orders....

  10. Monitoring Gold Nanoparticle Growth in Situ via the Acoustic Vibrations Probed by Four-Wave Mixing.

    Science.gov (United States)

    Wu, Jian; Xiang, Dao; Gordon, Reuven

    2017-02-21

    We monitor in situ gold nanoparticle growth in aqueous solution by probing the acoustic vibrations with four-wave mixing. We observe two acoustic vibrational modes of gold nanoparticles from the nonlinear optical response: an extensional mode with longitudinal expansion and transverse contraction and a breathing mode with radial expansion and contraction. The mode frequencies, which show an inverse dependence on the nanoparticle diameter, allow one to monitor the nanoparticle size and size distribution during synthesis. The information about the nanoparticle size and size distribution calculated on the basis of the mode frequencies agrees well with the results obtained from the electron microscopy analysis, validating the four-wave mixing technique as an accurate and effective tool for in situ monitoring of colloidal growth.

  11. Classical-to-quantum transition with broadband four-wave mixing.

    Science.gov (United States)

    Vered, Rafi Z; Shaked, Yaakov; Ben-Or, Yelena; Rosenbluh, Michael; Pe'er, Avi

    2015-02-13

    A key question of quantum optics is how nonclassical biphoton correlations at low power evolve into classical coherence at high power. Direct observation of the crossover from quantum to classical behavior is desirable, but difficult due to the lack of adequate experimental techniques that cover the ultrawide dynamic range in photon flux from the single photon regime to the classical level. We investigate biphoton correlations within the spectrum of light generated by broadband four-wave mixing over a large dynamic range of ∼80  dB in photon flux across the classical-to-quantum transition using a two-photon interference effect that distinguishes between classical and quantum behavior. We explore the quantum-classical nature of the light by observing the interference contrast dependence on internal loss and demonstrate quantum collapse and revival of the interference when the four-wave mixing gain in the fiber becomes imaginary.

  12. Enhancement of ultrafast four-wave mixing in a polar molecule medium.

    Science.gov (United States)

    Yang, Weifeng; Gong, Shangqing; Xu, Zhizhan

    2006-08-07

    We investigate the ultrafast four-wave mixing (FWM) with two-color few-cycle ultrashort pulses propagating in a two-level polar molecule medium. It is found that the enhancement of FWM can be achieved even for low intensity pulses due to the effects of permanent dipole moments (PDM) in polar molecules. Moreover, the conversion efficiency of FWM can be controlled by the carrier-envelope phases (CEP) of two ultrashort pulses.

  13. Spectrally resolved four-wave mixing in semiconductors: Influence of inhomogeneous broadening

    DEFF Research Database (Denmark)

    Erland, J.; Pantke, K.-H.; Mizeikis, V.

    1994-01-01

    We study the influence of inhomogeneous broadening on results obtained from spectrally resolved transient four-wave mixing. In particular, we study the case where more resonances are coherently excited, leading to polarization interference or quantum beats, depending on the microscopic nature of ...... of the resonances. To demonstrate the ideas, we present experimental results from bulk CdSe and from GaAs multiple quantum wells....

  14. Quantum exciton-polariton networks through inverse four-wave mixing

    Science.gov (United States)

    Liew, T. C. H.; Rubo, Y. G.

    2018-01-01

    We demonstrate the potential of quantum operation using lattices of exciton-polaritons in patterned semiconductor microcavities. By introducing an inverse four-wave mixing scheme acting on localized modes, we show that it is possible to develop nonclassical correlations between individual condensates. This allows a concept of quantum exciton-polariton networks, characterized by the appearance of multimode entanglement even in the presence of realistic levels of dissipation.

  15. Quantum properties of a parametric four-wave mixing in a Raman type atomic system

    Directory of Open Access Journals (Sweden)

    Sharypov A.V.

    2017-01-01

    Full Text Available We present a study of the quantum properties of two light fields used to parametric four-wave mixing in a Raman type atomic system. The system realizes an effective Hamiltonian of beamsplitter type coupling between the light fields, which allows to control squeezing and amplitude distribution of the light fields, as well as realizing their entanglement. The scheme can be feasibly applied to engineer the quantum properties of two single-mode light fields in properly chosen input states.

  16. Far-detuned cascaded intermodal four-wave mixing in a multimode fiber.

    Science.gov (United States)

    Dupiol, R; Bendahmane, A; Krupa, K; Tonello, A; Fabert, M; Kibler, B; Sylvestre, T; Barthelemy, A; Couderc, V; Wabnitz, S; Millot, G

    2017-04-01

    We demonstrate far-detuned parametric frequency conversion processes in a few mode graded-index optical fibers pumped by a Q-switched picosecond laser at 1064 nm. Through a detailed analytical and numerical analysis, we show that the multiple sidebands are generated through a complex cascaded process involving inter-modal four-wave mixing. The resulting parametric wavelength detuning spans in the visible down to 405 nm and in the near-infrared up to 1355 nm.

  17. Robust and compact entanglement generation from diode-laser-pumped four-wave mixing

    Energy Technology Data Exchange (ETDEWEB)

    Lawrie, B. J., E-mail: lawriebj@ornl.gov; Pooser, R. C. [Quantum Information Science Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Yang, Y. [Quantum Information Science Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Department of Physics, Wabash College, Crawfordsville, Indiana 47933 (United States); Eaton, M. [Quantum Information Science Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Department of Physics, Southern Illinois University Carbondale, Carbondale, Illinois 62901 (United States); Black, A. N. [Quantum Information Science Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Department of Physics and Astronomy, Middle Tennessee State University, Murfreesboro, Tennessee 37132 (United States)

    2016-04-11

    Four-wave-mixing processes are now routinely used to demonstrate multi-spatial-mode Einstein-Podolsky-Rosen entanglement and intensity difference squeezing. Diode-laser-pumped four-wave mixing processes have recently been shown to provide an affordable, compact, and stable source for intensity difference squeezing, but it was unknown if excess phase noise present in power amplifier pump configurations would be an impediment to achieving quadrature entanglement. Here, we demonstrate the operating regimes under which these systems are capable of producing entanglement and under which excess phase noise produced by the amplifier contaminates the output state. We show that Einstein-Podolsky-Rosen entanglement in two mode squeezed states can be generated by a four-wave-mixing source deriving both the pump field and the local oscillators from a tapered-amplifier diode-laser. This robust continuous variable entanglement source is highly scalable and amenable to miniaturization, making it a critical step toward the development of integrated quantum sensors and scalable quantum information processors, such as spatial comb cluster states.

  18. Influence of Four-Wave Mixing and Walk-Off on the Self-Focusing of Coupled Waves

    DEFF Research Database (Denmark)

    Bergé, L.; Bang, Ole; Krolikowski, W.

    2000-01-01

    Four-wave mixing and walk-off between two optical beams are! investigated For focusing Kerr media. It is shown that four-wave mixing reinforces the self-focusing of mutually trapped waves by lowering their power threshold for collapse, only when their phase mismatch is small. On the contrary, walk...

  19. Detailed phase matching characterization of inter-modal four-wave mixing in a two-mode fiber

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Jung, Y.; Begleris, I.

    2016-01-01

    We experimentally characterize the phase matching properties of two inter-modal four-wave mixing processes in a graded index fiber guiding the LP01 and LP11 mode-groups.......We experimentally characterize the phase matching properties of two inter-modal four-wave mixing processes in a graded index fiber guiding the LP01 and LP11 mode-groups....

  20. Spatially nondegenerate four-wave mixing in a broad area semiconductor laser: Modeling

    DEFF Research Database (Denmark)

    Jensen, Søren Blaaberg; Tromborg, Bjarne; Petersen, P. M.

    We present a numerical model of spatially nondegenerate four-wave mixing in a bulk broad area semiconductor laser with an external reflector and a spatial filter. The external reflector provides a feedback with an off-aixs direction of propagation. Such a configuration has experimentally been seen...... to improve the coherence of the output of a broad area laser. While the far-field of a broad area laser is often double-lobed. the reflector feeds only one of the lobes back into the cavity in the same angle as the emission angle. As our model assumes only four waves inside the cavity it consists of four...... coupled equations for the field components in the cavity and a rate equation is used to describe the carrier density of the semiconductor material. The interference pattern of the four field components inside the cavity induces a periodic spatial modulation of the carrier density and thus of the complex...

  1. Vortex algebra by multiply cascaded four-wave mixing of femtosecond optical beams.

    Science.gov (United States)

    Hansinger, Peter; Maleshkov, Georgi; Garanovich, Ivan L; Skryabin, Dmitry V; Neshev, Dragomir N; Dreischuh, Alexander; Paulus, Gerhard G

    2014-05-05

    Experiments performed with different vortex pump beams show for the first time the algebra of the vortex topological charge cascade, that evolves in the process of nonlinear wave mixing of optical vortex beams in Kerr media due to competition of four-wave mixing with self-and cross-phase modulation. This leads to the coherent generation of complex singular beams within a spectral bandwidth larger than 200nm. Our experimental results are in good agreement with frequency-domain numerical calculations that describe the newly generated spectral satellites.

  2. Femtosecond Non-degenerate Four Wave Mixing Spectroscopy: The Two Color Photon Echo Peak Shift

    CERN Document Server

    Prall, B S

    2005-01-01

    The couplings between multiple electronic states and electronic and nuclear coordinates are examined for condensed phase systems by femtosecond degenerate and non-degenerate four wave mixing. The two-color photon echo peak shift experiment is developed which allows measurement of the correlation between transition frequencies in two different spectral regions. Two-color photon echo peak shift (2C3PEPS) experiments are used to study coupling between electronic states in the lutetium bisphthalocyanine anion, LuPc2−. Electronically induced mixing between exciton and charge resonance states leads to correlations in transition energies for the two observed transitions. This correlation generates non-zero 2C3PEPS which, when compared with 1C3PEPS, allows experimental determination of the degree of mixing, which was in good agreement with theoretical predictions. By exploiting a coherently excited nuclear wavepacket, the nuclear dependence on the electronic mixing between exciton and charge resonance state...

  3. Nonlinear fiber-optic strain sensor based on four-wave mixing in microstructured optical fiber

    DEFF Research Database (Denmark)

    Gu, Bobo; Yuan, Scott Wu; Frosz, Michael H.

    2012-01-01

    We demonstrate a nonlinear fiber-optic strain sensor, which uses the shifts of four-wave mixing Stokes and anti-Stokes peaks caused by the strain-induced changes in the structure and refractive index of a microstructured optical fiber. The sensor thus uses the inherent nonlinearity of the fiber...... and does not require any advanced post-processing of the fiber. Strain sensitivity of -0.23 pm/mu epsilon is achieved experimentally and numerical simulations reveal that for the present fiber the sensitivity can be increased to -4.46 pm/mu epsilon by optimizing the pump wavelength and power....

  4. Nonlinear fiber-optic strain sensor based on four-wave mixing in microstructured optical fiber.

    Science.gov (United States)

    Gu, Bobo; Yuan, Wu; Frosz, Michael H; Zhang, A Ping; He, Sailing; Bang, Ole

    2012-03-01

    We demonstrate a nonlinear fiber-optic strain sensor, which uses the shifts of four-wave mixing Stokes and anti-Stokes peaks caused by the strain-induced changes in the structure and refractive index of a microstructured optical fiber. The sensor thus uses the inherent nonlinearity of the fiber and does not require any advanced postprocessing of the fiber. Strain sensitivity of -0.23 pm/με is achieved experimentally and numerical simulations reveal that for the present fiber the sensitivity can be increased to -4.46 pm/με by optimizing the pump wavelength and power. © 2012 Optical Society of America

  5. Observation of multi-component spatial vector solitons of four-wave mixing.

    Science.gov (United States)

    Wang, Ruimin; Wu, Zhenkun; Zhang, Yiqi; Zhang, Zhaoyang; Yuan, Chenzhi; Zheng, Huaibin; Li, Yuanyuan; Zhang, Jinhai; Zhang, Yanpeng

    2012-06-18

    We report the observation of multi-component dipole and vortex vector solitons composed of eight coexisting four-wave mixing (FWM) signals in two-level atomic system. The formation and stability of the multi-component dipole and vortex vector solitons are observed via changing the experiment parameters, including the frequency detuning, powers, and spatial configuration of the involved beams and the temperature of the medium. The transformation between modulated vortex solitons and rotating dipole solitons is observed at different frequency detunings. The interaction forces between different components of vector solitons are also investigated.

  6. Four-wave mixing in quantum dot SOAs: Theory of carrier heating

    Science.gov (United States)

    Flayyih, Ahmed H.; Al-Shatravi, Ali Gehad; Al-Khursan, Amin H.

    Carrier heating (CH) theory in a four-wave mixing quantum dot structure has been investigated. The impact of wetting layer (WL) carrier density, CH time constant, effective intraband relaxation time have been examined. The derived heat capacity for QD structure have (T-1) dependence. It is shown here that both WL carrier density and QD excited state (ES) occupation controls the overall nonlinear contributions. Then inclusion of WL and ES in the CH induces a new equilibrium reached at a faster recovery time. The proposed model yields results in a line with experiments at high carrier density reflecting the efficiency of our model.

  7. Demonstration of almost octave-spanning cascaded four-wave mixing in optical microfibers.

    Science.gov (United States)

    Li, Y H; Zhao, Y Y; Wang, L J

    2012-08-15

    We demonstrate almost octave-spanning cascaded four-wave mixing (CFWM) in optical microfibers. Pumped by two synchronized picosecond lasers at about 850 nm, microfibers with a length of 10-20 cm can generate CFWM spanning from a few hundred nanometers to almost one octave, depending on the diameter of the microfibers and the detuning between the two pumps. CFWM in microfibers, which has the advantages of easy fabrication, highly efficient coupling, relatively short length, and easy integration with fiber systems, can be used for applications in widely tunable multiline phase-sensitive amplification, multiwavelength coherent sources, and ultrashort pulse synthesis.

  8. Polarization resolved electric field measurements on plasma bullets in N2 using four-wave mixing

    Science.gov (United States)

    van der Schans, Marc; Boehm, Patrick; Nijdam, Sander; Ijzerman, Wilbert; Czarnetzki, Uwe

    2016-09-01

    Atmospheric pressure plasma jets generated by kHz AC or pulsed DC voltages typically consist of discrete guided ionization waves called plasma bullets. In this work, the electric field of plasma bullets generated in a pulsed DC jet with N2 as feed gas is investigated using the four-wave mixing method. In this diagnostic two laser beams, where one is Stokes shifted from the other, non-linearly interact with the N2 molecules and the bullet's electric field. As a result of the interaction a coherent anti-Stokes Raman scattered (CARS) beam and an infrared beam are generated from which the electric field can be determined. Compared to emission-based methods, this technique has the advantage of being able to also probe the electric field in regions around the plasma bullet where no photons are emitted. The four-wave mixing method and its analysis have been adapted to work with the non-uniform electric field of plasma bullets. In addition, an ex-situ calibration procedure using an electrode geometry different from the discharge geometry has been developed. An experimentally obtained radial profile of the axial electric field component of a plasma bullet in N2 is presented. The position of this profile is related to the location of the propagating bullet from temporally resolved images.

  9. Broadband Polarization-Insensitive Wavelength Conversion Based on Non-Degenerate Four-Wave Mixing in a Silicon Nanowire

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua

    2012-01-01

    We experimentally demonstrate broadband polarization-insensitive one-to-two wavelength conversion of a 10-Gb/s DPSK data signal based on non-degenerate four-wave mixing in a silicon nanowire with bit-error rate measurements.......We experimentally demonstrate broadband polarization-insensitive one-to-two wavelength conversion of a 10-Gb/s DPSK data signal based on non-degenerate four-wave mixing in a silicon nanowire with bit-error rate measurements....

  10. On-chip wavelength switch based on thermally tunable discrete four-wave mixing in a silicon waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Chen, Yaohui; Hu, Hao

    2014-01-01

    An on-chip wavelength switch is proposed based on discrete four-wave mixing in a silicon waveguide. Switching operation can be realized by thermal tuning the waveguide dispersion. We also discuss optimal dimension design concerning device performances.......An on-chip wavelength switch is proposed based on discrete four-wave mixing in a silicon waveguide. Switching operation can be realized by thermal tuning the waveguide dispersion. We also discuss optimal dimension design concerning device performances....

  11. Temporal imaging based on four-wave mixing in slow-light photonic crystal waveguide

    Science.gov (United States)

    Zhou, Mingyang; Liu, Hongjun; Wang, Zhaolu; Huang, Nan; Han, Jing

    2017-12-01

    We have proposed a temporal imaging system based on four-wave mixing (FWM) in the dispersion engineered slow-light photonic crystal waveguide (PCW). Dispersion relations of the modified PCW are calculated through the 3D plane wave expansion method. Time lens is demonstrated by solving the couple-mode equations describing the FWM process inside the PCW directly. Intensity and phase evolutions of the signal, pump and idler waves during the FWM process are calculated to investigate temporal imaging. Meanwhile, temporal magnifications with different magnification factors are realized by tuning the total dispersion of the input signals. Furthermore, influences of dispersion and free-carrier effects inside PCW on the temporal imaging performance are analyzed. The simulation results show the capability to realize temporal imaging system based on the FWM process in slow-light engineered PCW.

  12. Vacuum-induced suppression and enhancement of four-wave mixing in an optical cavity

    Science.gov (United States)

    Chen, Haixia; Wang, Xiuxiu; Ahmed, Irfan; Yao, Xin; Wu, Zhenkun; Zhu, Dayu; Zhang, Yanpeng

    2015-09-01

    We report on an experimental study of vacuum-induced suppression and enhancement of four-wave mixing (FWM) signal in a composite atom-cavity system. By scanning the additional dressing field, the suppression ratio of the FWM signal can reach 90 % compared with 40 % without cavity. We attribute the enhanced suppression and enhancement to the atom-cavity coupling arising from a vacuum-induced Raman process, which amplifies the dressing effect from the additional field. Also, the dressing asymmetry of the atom-cavity coupling is discussed and used to estimate the nonlinearity of atomic medium in the cavity. The suppression and enhancement can be interpreted by a dressed-state picture and agree with theoretical calculations. The investigation may find applications in optical switch and quantum memory controlled by cavity.

  13. Quantitative degenerate four-wave mixing spectroscopy: Probes for molecular species

    Energy Technology Data Exchange (ETDEWEB)

    Farrow, R.; Rakestraw, D.; Paul, P.; Lucht, R.; Danehy, P.; Friedman-Hill, E.; Germann, G. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    Resonant degenerate four-wave mixing (DFWM) is currently the subject of intensive investigation as a sensitive diagnostic tool for molecular species. DFWM has the advantage of generating a coherent (beam-like) signal which results in null-background detection and provides excellent immunity to background-light interference. Since multiple one-photon resonances are involved in the signal generation process, the DFWM technique can allow sensitive detection of molecules via electronic, vibrational or rotational transitions. These properties combine to make DFWM a widely applicable diagnostic technique for the probing of molecular species. The authors are conducting fundamental and applied investigations of DFWM for quantitative measurements of trace species in reacting gases. During the past year, efforts have been focussed in two areas: (1) understanding the effects of collisional processes on the DFWM signal generation process, and (2) exploring the applicability of infrared DFWM to detect polyatomic molecules via rovibrational transitions.

  14. Observation of the four wave mixing photonic band gap signal in electromagnetically induced grating.

    Science.gov (United States)

    Ullah, Zakir; Wang, Zhiguo; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2014-12-01

    For the first time, we experimentally and theoretically research about the probe transmission signal (PTS), the reflected four wave mixing band gap signal(FWM BGS) and fluorescence signal (FLS) under the double dressing effect in an inverted Y-type four level system. FWM BGS results from photonic band gap structure. We demonstrate that the characteristics of PTS, FWM BGS and FLS can be controlled by power, phase and the frequency detuning of the dressing beams. It is observed in our experiment that FWM BGS switches from suppression to enhancement, corresponding to the switch from transmission enhancement to absorption enhancement in the PTS with changing the relative phase. We also observe the relation among the three signals, which satisfy the law of conservation of energy. Such scheme could have potential applications in optical diodes, amplifiers and quantum information processing.

  15. Identification of a new low energy 1ustate in dicopper with resonant four-wave mixing.

    Science.gov (United States)

    Visser, B; Beck, M; Bornhauser, P; Knopp, G; van Bokhoven, J A; Marquardt, R; Gourlaouen, C; Radi, P P

    2017-12-07

    The low energy electronic structure of the copper dimer has been re-investigated using non-linear four-wave mixing spectroscopy and high level ab initio calculations. In addition to the measurement of the previously reported A, B, and C electronic states, a new state denoted A' is identified with T 0 = 20 100.4090(16) cm -1 ( 63 Cu 2 ). Rotational analysis of the A'-X (0,0) and (1,0) transitions leads to the assignment of A' 1 u . Ab initio calculations present the first theoretical description of the low energy states of the copper dimer in Hund's case (c) and confirm the experimental assignment. The discovery of this new low energy excited state emphasizes that spin-orbit coupling is significant in states with d-hole electronic configurations and resolves a decades-long mystery in the initial assignment of the A state.

  16. Stimulated generation of superluminal light pulses via four-wave mixing.

    Science.gov (United States)

    Glasser, Ryan T; Vogl, Ulrich; Lett, Paul D

    2012-04-27

    We report on the four-wave mixing of superluminal pulses, in which both the injected and generated pulses involved in the process propagate with negative group velocities. Generated pulses with negative group velocities of up to v(g)=-1/880c are demonstrated, corresponding to the generated pulse's peak exiting the 1.7 cm long medium ≈50 ns earlier than if it had propagated at the speed of light in vacuum, c. We also show that in some cases the seeded pulse may propagate with a group velocity larger than c, and that the generated conjugate pulse peak may exit the medium even earlier than the amplified seed pulse peak. We can control the group velocities of the two pulses by changing the seed detuning and the input seed power.

  17. Competing four-wave mixing processes in dispersion oscillating telecom fiber.

    Science.gov (United States)

    Finot, Christophe; Fatome, Julien; Sysoliatin, Alexej; Kosolapov, A; Wabnitz, Stefan

    2013-12-15

    We experimentally study the dynamics of the generation of multiple sidebands by means of a quasi-phase-matched four-wave mixing (FWM) process occurring in a dispersion-oscillating, highly nonlinear optical fiber. The fiber under test is pumped by a ns microchip laser operating in the normal average group-velocity dispersion regime and in the telecom C band. We reveal that the growth of higher-order sidebands is strongly influenced by the competition with cascade FWM between the pump and the first-order quasi-phase matched sidebands. The properties of these competing FWM processes are substantially affected when a partially coherent pump source is used, leading to a drastic reduction of the average power needed for sideband generation.

  18. Nonlinear Sagnac interferometer based on the four-wave mixing process.

    Science.gov (United States)

    Xin, Jun; Liu, Jinming; Jing, Jietai

    2017-01-23

    A new nonlinear Sagnac interferometer (NSI) is proposed by replacing the beam-splitter in the traditional Sagnac interferometer (TSI) with a four-wave mixing process. Such a NSI has better angular velocity sensitivity than the one of the TSI. The standard quantum limit can be beaten and the Heisenberg Limit can even be reached for the ideal case by the NSI. We study the effect of the losses on the angular velocity sensitivity of the NSI and find that the optimal angular velocity, where the best angular velocity sensitivity can be obtained, of the NSI may be dependent on the losses inside the interferometer. Such a NSI has its advantages compared with the TSI and may find its potential applications in quantum metrology.

  19. Phase-locking in Multi-Frequency Brillouin Oscillator via Four Wave Mixing

    CERN Document Server

    Buettner, Thomas F S; Hudson, Darren D; Pant, Ravi; Poulton, Christopher G; Judge, Alexander C; Eggleton, Benjamin J

    2014-01-01

    Stimulated Brillouin scattering (SBS) and Kerr-nonlinear four wave-mixing (FWM) are among the most important and widely studied nonlinear effects in optical fibres. At high powers SBS can be cascaded producing multiple Stokes waves spaced by the Brillouin frequency shift. Here, we investigate the complex nonlinear interaction of the cascade of Stokes waves, generated in a Fabry-Perot chalcogenide fibre resonator through the combined action of SBS and FWM. We demonstrate the existence of parameter regimes, in which pump and Stokes waves attain a phase-locked steady state. Real-time measurements of 40ps pulses with 8GHz repetition rate are presented, confirming short-and long-term stability. Numerical simulations qualitatively agree with experiments and show the significance of FWM in phase-locking of pump and Stokes waves. Our findings can be applied for the design of novel picosecond pulse sources with GHz repetition rate for optical communication systems.

  20. Optical bistability and four-wave mixing in a hybrid optomechanical system

    Science.gov (United States)

    Jiang, Lei; Yuan, Xiaorong; Cui, Yuanshun; Chen, Guibin; Zuo, Fen; Jiang, Cheng

    2017-10-01

    We explore theoretically the optical bistability and four-wave mixing (FWM) in a hybrid optomechanical system, where the mechanical resonator is simultaneously coupled to a cavity field and a two-level system (qubit). We can use a strong control field driving the cavity to control the bistable behavior of the steady-state photon number, phonon number, and the population inversion. The impact of qubit-resonator coupling strength on the bistable behavior is discussed. Furthermore, the two-level system can significantly modify the output fields of the cavity, leading to double optomechanically induced transparency (OMIT) and the enhancement of the FWM intensity. We find that the distance between the two peaks in the FWM spectrum can be controlled by the qubit-resonator coupling strength, and the peak value of the FWM intensity can be adjusted by the Rabi frequency of the control field.

  1. Tuneable four-wave mixing in AlGaAs nanowires.

    Science.gov (United States)

    Dolgaleva, Ksenia; Sarrafi, Peyman; Kultavewuti, Pisek; Awan, Kashif M; Feher, Norbert; Aitchison, J Stewart; Qian, Li; Volatier, Maïté; Arès, Richard; Aimez, Vincent

    2015-08-24

    We have experimentally demonstrated broadband tuneable four-wave mixing in AlGaAs nanowires with the widths ranging between 400 and 650 nm and lengths from 0 to 2 mm. We performed a detailed experimental study of the parameters influencing the FWM performance in these devices (experimental conditions and nanowire dimensions). The maximum signal-to-idler conversion range was 100 nm, limited by the tuning range of the pump source. The maximum conversion efficiency, defined as the ratio of the output idler power to the output signal power, was -38 dB. In support of our explanation of the experimentally observed trends, we present modal analysis and group velocity dispersion numerical analysis. This study is what we believe to be a step forward towards realization of all-optical signal processing devices.

  2. Degenerate four-wave-mixing in a silica hollow bottle-like microresonator

    CERN Document Server

    Yang, Yong; Thompson, Ruth; Ward, Jonathan; Chormaic, Síle Nic

    2015-01-01

    A hollow bottle-like microresonator (BLMR) with ultra-high quality factor is fabricated from a microcapillary with nearly parabolic profile. At 1.55 $\\mu m$ pumping, degenerate four-wave mixing can be observed for a BLMR of diameter 102 $\\mu$m. The parabolic profile of the BLMR guarantees a nearly zero waveguide dispersion, which is theoretically discussed in detail. From the simulation, at 1.55 $\\mu$m wavelength in such a BLMR, the fundamental bottle mode is in the anomalous dispersion regime, whilst the ordinary whispering gallery mode (WGM) confined at the center of the BLMR is in the normal dispersion regime. Experimentally, no degenerate FWM is observed for the WGM selected by positioning the coupling tapered fiber in the same BLMR. Furthermore, dispersion tuning is briefly discussed. As the work predicted, the BLMR shows promise for the implementation of sparsely distributed, widely spanned frequency combs at the telecommunication wavelength.

  3. Sub-10 fs deep-ultraviolet pulses generated by chirped-pulse four-wave mixing.

    Science.gov (United States)

    Kida, Yuichiro; Liu, Jun; Teramoto, Takahiro; Kobayashi, Takayoshi

    2010-06-01

    We propose and demonstrate experimentally a novel way of generating sub-10fs deep-UV pulses. The technique is based on chirped-pulse four-wave mixing induced by a broadband near-IR (NIR) pulse and a near-UV pulse. The broadband IR pulse is prepared by preliminarily broadening the spectral width of an NIR pulse by self-phase modulation. The positively chirped broadband IR pulse is suitable for generating a negatively chirped deep-UV pulse, which can be compressed by normal group-velocity dispersion in a transparent medium. Self-compression of the generated deep-UV pulse in air has been demonstrated to produce sub-10fs deep-UV pulses with excellent temporal and spectral profiles for ultrafast spectroscopy in the deep UV.

  4. Inter-modal four-wave mixing study in a two-mode fiber

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Begleris, I.; Jung, Y.

    2016-01-01

    We demonstrate efficient four-wave mixing among different spatial modes in a 1-km long two-mode fiber at telecommunication wavelengths. Two pumps excite the LP01 and LP11 modes, respectively, while the probe signal excites the LP01 mode, and the phase conjugation (PC) and Bragg scattering (BS......) idlers are generated in the LP11 mode. For these processes we experimentally characterize their phase matching efficiency and bandwidth and find that they depend critically on the wavelength separation of the two pumps, in good agreement with the numerical study we carried out. We also confirm...... experimentally that BS has a larger bandwidth than PC for the optimum choice of the pump wavelength separation....

  5. Generating quantum correlated twin beams by four-wave mixing in hot cesium vapor

    Science.gov (United States)

    Ma, Rong; Liu, Wei; Qin, Zhongzhong; Jia, Xiaojun; Gao, Jiangrui

    2017-10-01

    Using a nondegenerate four-wave mixing process based on a double-Λ scheme in hot cesium vapor, we generate quantum correlated twin beams with a maximum intensity-difference squeezing of 6.5 dB. The substantially improved squeezing can be mainly attributed to very good frequency and phase-difference stability between the pump and probe beams in our experiment. Intensity-difference squeezing can be observed within a wide experimental parameter range, which guarantees its robust generation. Since this scheme produces multi-spatial-mode twin beams at the Cs D1 line, it is of interest for experiments involving quantum imaging and coherent interfaces between atomic and solid-state systems.

  6. Visualization of Oil Body Distribution in Jatropha curcas L. by Four-Wave Mixing Microscopy

    Science.gov (United States)

    Ishii, Makiko; Uchiyama, Susumu; Ozeki, Yasuyuki; Kajiyama, Sin'ichiro; Itoh, Kazuyoshi; Fukui, Kiichi

    2013-06-01

    Jatropha curcas L. (jatropha) is a superior oil crop for biofuel production. To improve the oil yield of jatropha by breeding, the development of effective and reliable tools to evaluate the oil production efficiency is essential. The characteristics of the jatropha kernel, which contains a large amount of oil, are not fully understood yet. Here, we demonstrate the application of four-wave mixing (FWM) microscopy to visualize the distribution of oil bodies in a jatropha kernel without staining. FWM microscopy enables us to visualize the size and morphology of oil bodies and to determine the oil content in the kernel to be 33.2%. The signal obtained from FWM microscopy comprises both of stimulated parametric emission (SPE) and coherent anti-Stokes Raman scattering (CARS) signals. In the present situation, where a very short pump pulse is employed, the SPE signal is believed to dominate the FWM signal.

  7. Heterodyne pump-probe and four-wave mixing in semiconductor optical amplifiers using balanced lock-in detection

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang; Mørk, Jesper

    1999-01-01

    We demonstrate a new detection scheme for pump-probe and four-wave mixing heterodyne experiments, using balanced detection and a dual-phase lock-in for spectral filtering. The technique allows the use of low repetition-rate laser systems, as is demonstrated on an InGaAsP/InP bulk optical amplifier....... The results for small perturbations are consistent with previous pump-probe experiments reported in literature. Time-resolved four-wave mixing in the absorption regime of the device is measured, and compared with numerical simulations, indicating a 100 fs dephasing time....

  8. Electric field measurements on plasma bullets in N2 using four-wave mixing

    Science.gov (United States)

    van der Schans, Marc; Böhm, Patrick; Teunissen, Jannis; Nijdam, Sander; IJzerman, Wilbert; Czarnetzki, Uwe

    2017-11-01

    Atmospheric pressure plasma jets generated by kHz nanosecond voltage pulses typically consist of guided streamer discharges called plasma bullets. In this work, plasma bullets are generated in a pulsed plasma jet using N2 as feed gas and their electric field distribution is investigated by polarization-resolved four-wave mixing. The method and its analysis have been extended to resolve radial profiles of non-uniform, but radially symmetric, electric field distributions. In addition, a calibration procedure using an electrode geometry different from the discharge geometry has been developed. A radially resolved profile of the axial electric field component of a plasma bullet in N2 is presented, as well as the temporal development of the (line-integrated) radial and axial components of the electric field. To verify the results, they are compared to a streamer model adapted to the conditions of the experiment. The peak values obtained from the experiment are in the range expected from streamer literature. However, there are some quantitative differences with the model, which predicts values approximately a factor two lower than those found in the experiment, as well as a faster radial decay. The temporal development shows similar features in both the experiment and the model. Explanations for these differences are provided and further improvements for the method are outlined.

  9. Time-resolved four-wave-mixing spectroscopy for inner-valence transitions

    CERN Document Server

    Ding, Thomas; Kaldun, Andreas; Blättermann, Alexander; Meyer, Kristina; Stooß, Veit; Rebholz, Marc; Birk, Paul; Hartmann, Maximilian; Brown, Andrew; Van Der Hart, Hugo; Pfeifer, Thomas

    2015-01-01

    Non-collinear four-wave mixing (FWM) techniques at near-infrared (NIR), visible, and ultraviolet frequencies have been widely used to map vibrational and electronic couplings, typically in complex molecules. However, correlations between spatially localized inner-valence transitions among different sites of a molecule in the extreme ultraviolet (XUV) spectral range have not been observed yet. As an experimental step towards this goal we perform time-resolved FWM spectroscopy with femtosecond NIR and attosecond XUV pulses. The first two pulses (XUV-NIR) coincide in time and act as coherent excitation fields, while the third pulse (NIR) acts as a probe. As a first application we show how coupling dynamics between odd- and even-parity inner-valence excited states of neon can be revealed using a two-dimensional spectral representation. Experimentally obtained results are found to be in good agreement with ab initio time-dependent R-matrix calculations providing the full description of multi-electron interactions,...

  10. Broadband Enhancement of Optical Frequency Comb Using Cascaded Four-Wave Mixing in Photonic Crystal Fiber

    Directory of Open Access Journals (Sweden)

    Tawfig Eltaif

    2017-01-01

    Full Text Available A cascaded intensity modulator (IM and phase modulator (PM are used to modulate a continuous-wave (CW laser and generate an optical frequency comb (OFC. Thus, the generated comb is utilized as an initial seed and combined with another CW-laser to generate four-wave mixing (FWM in photonic crystal fiber (PCF. Results show that an initial flat 30 GHz OFC of 29, 55 lines within power fluctuation of 0.8 dB and 2 dB, respectively, can be achieved by setting the ratio of the DC bias to amplitude of sinusoidal signal at 0.1 and setting the modulation indices of both IM and PM at 10. Moreover, the 1st order of FWM created through 14 m of PCF has over 68 and 94 lines with fluctuation of 0.8 dB and 2 dB, respectively. Hence, the generated wavelengths of 1st left and right order of FWM can be tuned in a range from ~1500 nm to ~1525 nm and ~1590 nm to ~1604 nm, respectively.

  11. Polarization-dependent intermodal four-wave mixing in a birefringent multimode photonic crystal fiber.

    Science.gov (United States)

    Yuan, Jinhui; Kang, Zhe; Li, Feng; Zhou, Guiyao; Sang, Xinzhu; Wu, Qiang; Yan, Binbin; Zhou, Xian; Zhong, Kangping; Wang, Liang; Wang, Kuiru; Yu, Chongxiu; Lu, Chao; Tam, Hwa Yaw; Wai, P K A

    2017-05-01

    In this Letter, polarization-dependent intermodal four-wave mixing (FWM) is demonstrated experimentally in a birefringent multimode photonic crystal fiber (BM-PCF) designed and fabricated in-house. Femtosecond pump pulses at wavelengths ∼800  nm polarized along one of the principal axes of the BM-PCF are coupled into a normal dispersion region away from the zero-dispersion wavelengths of the fundamental guided mode of the BM-PCF. Anti-Stokes and Stokes waves are generated in the 2nd guided mode at visible and near-infrared wavelengths, respectively. For pump pulses at an average input power of 500 mW polarized along the slow axis, the conversion efficiencies ηas and ηs of the anti-Stokes and Stokes waves generated at wavelengths 579.7 and 1290.4 nm are 19% and 14%, respectively. For pump pulses polarized along the fast axis, the corresponding ηas and ηs at 530.4 and 1627 nm are 23% and 18%, respectively. We also observed that fiber bending and intermodal walk-off have a small effect on the polarization-dependent intermodal FWM-based frequency conversion process.

  12. Electric field strength determination in filamentary DBDs by CARS-based four-wave mixing

    Science.gov (United States)

    Boehm, Patrick; Kettlitz, Manfred; Brandenburg, Ronny; Hoeft, Hans; Czarnetzki, Uwe

    2016-09-01

    The electric field strength is a basic parameter of non-thermal plasmas. Therefore, a profound knowledge of the electric field distribution is crucial. In this contribution a four wave mixing technique based on Coherent Anti-Stokes Raman spectroscopy (CARS) is used to measure electric field strengths in filamentary dielectric barrier discharges (DBDs). The discharges are operated with a pulsed voltage in nitrogen at atmospheric pressure. Small amounts hydrogen (10 vol%) are admixed as tracer gas to evaluate the electric field strength in the 1 mm discharge gap. Absolute values of the electric field strength are determined by calibration of the CARS setup with high voltage amplitudes below the ignition threshold of the arrangement. Alteration of the electric field strength has been observed during the internal polarity reversal and the breakdown process. In this case the major advantage over emission based methods is that this technique can be used independently from emission, e.g. in the pre-phase and in between two consecutive, opposite discharge pulses where no emission occurs at all. This work was supported by the Deutsche Forschungsgemeinschaft, Forschergruppe FOR 1123 and Sonderforschungsbereich TRR 24 ``Fundamentals of complex plasmas''.

  13. Fiber-based source for multiplex-CARS microscopy based on degenerate four-wave mixing.

    Science.gov (United States)

    Gottschall, Thomas; Baumgartl, Martin; Sagnier, Aude; Rothhardt, Jan; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2012-05-21

    We present a fiber-based laser source for multiplex coherent anti-Stokes Raman scattering (CARS) microscopy. This source is very compact and potentially alignment-free. The corresponding pump and Stokes pulses for the CARS process are generated by degenerate four-wave mixing (FWM) in photonic-crystal fibers. In addition, an ytterbium-doped fiber laser emitting spectrally narrow 100 ps pulses at 1035 nm wavelength serves as pump for the FWM frequency conversion. The FWM process delivers narrow-band pulses at 648 nm and drives a continuum-like spectrum ranging from 700 to 820 nm. With the presented source vibrational resonances with energies between 1200 cm-1 and 3200 cm-1 can be accessed with a resolution of 10 cm-1. Additionally, the temporal characteristics of the FWM output have been investigated by a cross-correlation setup, revealing the suitability of the emitted pulses for CARS microscopy. This work marks a significant step towards a simple and powerful all-fiber, maintenance-free multiplex-CARS source for real-world applications outside a laboratory environment.

  14. Continuum contribution to excitonic four-wave mixing due to interaction-induced nonlinearities: A numerical study

    DEFF Research Database (Denmark)

    Sayed, Karim El; Birkedal, Dan; Vadim, Lyssenko

    1997-01-01

    We present a theoretical investigation of ultrafast transient four-wave mixing (FWM) of GaAs quantum wells for coherent excitation of excitons and a large number of continuum states. It is shown that in this case the line shape of the FWM signal is drastically altered due to an interaction-induce...

  15. Optimisation of 40 Gb/s wavelength converters based on four-wave mixing in a semiconductor optical amplifier

    DEFF Research Database (Denmark)

    Schulze, K.; Petersen, Martin Nordal; Herrera, J.

    2007-01-01

    The optimum operating powers and wavelengths for a 40 Gb/s wavelength converter based on four-wave mixing in a semiconductor 14 optical amplifier are inferred from experimental results. From these measurements, some general rules of thumb are derived for this kind of devices. Generally, the optimum...

  16. Intermodal and cross-polarization four-wave mixing in large-core hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Olausson, Christina Bjarnal Thulin

    2015-01-01

    Degenerate four-wave mixing is considered in large mode area hybrid photonic crystal fibers, combining photonic bandgap guidance and index guidance. Co- and orthogonally polarized pump, signal and idler fields are considered numerically by calculating the parametric gain and experimentally...

  17. Phase-sensitive Four-wave Mixing in AlGaAs-on-Insulator Nano-waveguides

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Pu, Minhao; Ottaviano, Luisa

    2016-01-01

    Phase-sensitive four-wave mixing is experimentally demonstrated in a 5-mm long AlGaAsOI nano-waveguide. More than 7 dB of phase-sensitive extinction ratio are reported without neither using active biasing nor polarization-assisted schemes. Measurements show a good match with numerical predictions....

  18. Transient and time-resolved four-wave mixing with collinear pump and probe pulses using the heterodyne technique

    DEFF Research Database (Denmark)

    Mecozzi, A.; Mørk, Jesper

    1998-01-01

    We review the recently proposed heterodyne technique for four-wave mixing experiments with collinear and co-polarized pulses. We discuss issues related to the parameters of the nonlinear dynamics of the sample that can be extracted by this technique....

  19. Sensitive absorption detection for micro-column liquid chromatography by ultraviolet forward-scattering degenerate four-wave mixing.

    NARCIS (Netherlands)

    de Beer, T.; Beso, P.; Velthorst, N.H.; Brinkman, U.A.T.; Gooijer, C.; Hoornweg, G.Ph.

    1999-01-01

    The performance of forward-scattering degenerate four-wave mixing (F-D4WM) in the mid-ultraviolet (UV) region (351nm) as a detection technique for micro-column liquid chromatography (μLC) is studied, using nitro-substituted polycyclic aromatic hydrocarbons (NO

  20. Bragg-Scattering Four-Wave Mixing in Nonlinear Fibers with Intracavity Frequency-Shifted Laser Pumps

    Directory of Open Access Journals (Sweden)

    Katarzyna Krupa

    2012-01-01

    Full Text Available We experimentally study four-wave mixing in highly nonlinear fibers using two independent and partially coherent laser pumps and a third coherent signal. We focus our attention on the Bragg-scattering frequency conversion. The two pumps were obtained by amplifying two Intracavity frequency-shifted feedback lasers working in a continuous wave regime.

  1. Low-noise mid-IR upconversion detector for improved IR-degenerate four-wave mixing gas sensing

    DEFF Research Database (Denmark)

    Høgstedt, Lasse; Dam, Jeppe Seidelin; Sahlberg, Anna-Lena

    2014-01-01

    -to-noise ratio. The two detectors are compared for the detection of a coherent degenerate four-wave mixing (DFWM) signal in the mid-infrared, and applied to measure trace-level acetylene in a gas flow at atmospheric pressure, probing its fundamental rovibrational transitions. In addition to lower noise...

  2. Full-vectorial propagation model and modified effective mode area of four-wave mixing in straight waveguides

    DEFF Research Database (Denmark)

    Guo, Kai; Friis, Søren Michael Mørk; Christensen, Jesper Bjerge

    2017-01-01

    We derive from Maxwell's equations full-vectorial nonlinear propagation equations of four-wave mixing valid in straight semiconductor-on-insulator waveguides. Special attention is given to the resulting effective mode area, which takes a convenient form known from studies in photonic crystal fibers...

  3. Nanoroughness localization of excitons in GaAs multiple quantum wells studied by transient four-wave mixing

    DEFF Research Database (Denmark)

    Birkedal, Dan; Vadim, Lyssenko; Pantke, Karl-Heinz

    1995-01-01

    The interface roughness on a nanometer scale plays a decisive role in dephasing of excitons in GaAs multiple quantum wells. The excitonic four-wave mixing signal shows a free polarization decay and a corresponding homogeneously broadened line from areas with interface roughness on a scale larger ...

  4. Fundamentals of Highly Non-Degenerate Cascaded Four-Wave Mixing

    Directory of Open Access Journals (Sweden)

    Rosa Weigand

    2015-09-01

    Full Text Available By crossing two intense ultrashort laser pulses with different colors in a transparent medium, like a simple piece of glass, a fan of multicolored broadband light pulses can be simultaneously generated. These newly generated pulses are emitted in several well-defined directions and can cover a broad spectral range, from the infrared to the ultraviolet and beyond. This beautiful phenomenon, first observed and described 15 years ago, is due to highly-nondegenerate cascaded four-wave mixing (cascaded FWM, or CFWM. Here, we present a review of our work on the generation and measurement of multicolored light pulses based on third-order nonlinearities in transparent solids, from the discovery and first demonstration of highly-nondegenerate CFWM, to the coherent synthesis of single-cycle pulses by superposition of the multicolored light pulses produced by CFWM. We will also present the development and main results of a dedicated 2.5-D nonlinear propagation model, i.e., with propagation occurring along a two-dimensional plane while assuming cylindrically symmetric pump beam profiles, capable of adequately describing noncollinear FWM and CFWM processes. A new method for the generation of femtosecond pulses in the deep-ultraviolet (DUV based on FWM and CFWM will also be described. These experimental and theoretical results show that highly-nondegenerate third-order nonlinear optical processes are formally well understood and provide broader bandwidths than other nonlinear optical processes for the generation of ultrashort light pulses with wavelengths extending from the near-infrared to the deep-ultraviolet, which have many applications in science and technology.

  5. Quantitative measurement of rubidium isotope ratio using forward degenerate four-wave mixing

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Xuemei [State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, National Photoelectric Technology, and Functional Materials and Application of Science and Technology International Cooperation Center, Northwest University, Xi' an 710069 (China); Ren Zhaoyu, E-mail: rzy@nwu.edu.cn [State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, National Photoelectric Technology, and Functional Materials and Application of Science and Technology International Cooperation Center, Northwest University, Xi' an 710069 (China); Wang Jian; Miao Yizhu [State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, National Photoelectric Technology, and Functional Materials and Application of Science and Technology International Cooperation Center, Northwest University, Xi' an 710069 (China); Xu Xinlong [State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, National Photoelectric Technology, and Functional Materials and Application of Science and Technology International Cooperation Center, Northwest University, Xi' an 710069 (China); Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Jia Lajiang [State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, National Photoelectric Technology, and Functional Materials and Application of Science and Technology International Cooperation Center, Northwest University, Xi' an 710069 (China); Fan Haiming, E-mail: haiming.fan@nuigalway.ie [State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, National Photoelectric Technology, and Functional Materials and Application of Science and Technology International Cooperation Center, Northwest University, Xi' an 710069 (China); School of Physics, National University of Ireland Galway (NUIG), Galway (Ireland); and others

    2012-04-15

    In the present study, forward degenerate four-wave mixing (FDFWM) is employed to measure rubidium (Rb) isotope ratio quantitatively with excellent reproducibility regardless of laser intensity turbulence. The effects of power saturation, atomic absorption and Doppler broadening on measurements are investigated. The results indicate that optimized pump power for isotope ratio measurement is 5-37.3 mW and the optimized atomic number density is around 10{sup 14} m{sup -3} for the sample cell with a length of 50 mm. In addition, the signal of FDFWM is almost independent on Doppler effect in isotope ratio determination. The measured {sup 85}Rb and {sup 87}Rb ratios in Rb vapor cell and RbCl are 2.590 {+-} 0.001 and 2.649 {+-} 0.002 respectively, which are in good agreement with the values obtained by absorption spectroscopy and mass spectrometry. A low detection limit as 18.41 fg/mL is achieved. The information obtained from this work suggests that FDFWM is a reliable laser spectroscopic technique in quantitative isotope trace analysis for various applications such as geological and archeological dating. - Highlights: Black-Right-Pointing-Pointer Rb isotope ratio was quantitatively determined with DFWM for the first time. Black-Right-Pointing-Pointer Saturation effect and atomic absorption were studied to optimize the parameters. Black-Right-Pointing-Pointer High resolution was realized in graphite furnace with high temperature of 2000 Degree-Sign C. Black-Right-Pointing-Pointer Detection limit as low as 18.41 fg/mL was achieved.

  6. Efficient four-wave mixing by usage of resonances in mercury; Effizientes Vierwellenmischen durch Ausnutzen von Resonanzen in Quecksilber

    Energy Technology Data Exchange (ETDEWEB)

    Kolbe, Daniel

    2011-05-05

    A continuous, coherent radiation source in the vacuum ultraviolet spectral region is presented. It is based on four-wave-mixing in mercury vapor with fundamental beams at 253.7 nm, 407.9 nm und 545.5 nm wavelength. The fundamental beams are produced by frequency doubling and quadrupling of beams from solid-state laser-systems respectively. Due to the 6{sup 1}S-7{sup 1}S two-photon resonance and additionally the 6{sup 1}S-6{sup 3}P one-photon resonance the efficiency can be increased compared to former sources. A near one-photon resonance reduces the optimal phasematching temperature of the four-wave-mixing process. This leads to smaller Doppler and pressure broadening resulting in a higher four-wave-mixing efficiency. A maximum power of 0.3 nW at 121.56 nm wavelength, the 1S-2P Lyman-{alpha} transition in hydrogen, can be obtained. This Lyman-{alpha} source is needed for future laser cooling of antihydrogen. Apart from the Lyman-{alpha} generation, four-wave-mixing with a slightly different third fundamental wavelength results in radiation near a one-photon resonance in the VUV at the 6{sup 1}S-12{sup 1}P transition in mercury. Due to this additional one-photon resonance the nonlinear susceptibility, responsible for the four-wave-mixing, can be strongly increased without an influence on the phasematching. With such a mixing process the efficiency can be enlarged by three orders of magnitude and powers up to 6 {mu}W in the VUV could be realised. This is an improvement of a factor of 30 to former laser sources in this VUV regime. Furthermore the two-photon resonance of mercury could be investigated in detail. We observed a velocity-selective double resonance at small Rabi frequencies of the fundamental beams, which has the same origin as dark resonances in {lambda}-systems. At high Rabi frequencies excitation to the two-photon level can be high enough to initiate a laser process on the 7{sup 1}S-6{sup 1}P transition. This process could be observed with continuouswave

  7. Broadband and Efficient Dual-Pump Four-Wave Mixing in AlGaAs-On-Insulator Nano-Waveguide

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Pu, Minhao; Ottaviano, Luisa

    2016-01-01

    We characterize dual-pump four-wave-mixing in AlGaAs-on-insulator nano-waveguides and demonstrate an output conversion efficiency as high as -8.5 dB at 155-mW pump power. The idler optical signal-to-noise ratio is above 25 dB over a 26-nm bandwidth.......We characterize dual-pump four-wave-mixing in AlGaAs-on-insulator nano-waveguides and demonstrate an output conversion efficiency as high as -8.5 dB at 155-mW pump power. The idler optical signal-to-noise ratio is above 25 dB over a 26-nm bandwidth....

  8. Broadband and efficient dual-pump four-wave-mixing in AlGaAs-on-insulator nano-waveguides

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Pu, Minhao; Ottaviano, Luisa

    2016-01-01

    We characterize dual-pump four-wave-mixing in AlGaAs-on-insulator nano-waveguides and demonstrate an output conversion efficiency as high as −8.5 dB at 155-mW pump power. The idler optical signal-to-noise ratio is above 25 dB over a 26-nm bandwidth.......We characterize dual-pump four-wave-mixing in AlGaAs-on-insulator nano-waveguides and demonstrate an output conversion efficiency as high as −8.5 dB at 155-mW pump power. The idler optical signal-to-noise ratio is above 25 dB over a 26-nm bandwidth....

  9. Four-wave mixing parametric oscillation and frequency comb generation at visible wavelengths in a silica microbubble resonator

    CERN Document Server

    Yang, Yong; Kasumie, Sho; Zhao, Guangming; Xu, Linhua; Ward, Jonathan; Yang, Lan; Chormaic, Síle Nic

    2016-01-01

    Frequency comb generation in microresonators at visible wavelengths has found applications in a variety of areas such as metrology, sensing, and imaging. To achieve Kerr combs based on four-wave mixing in a microresonator, dispersion must be in the anomalous regime. In this work, we demonstrate dispersion engineering in a microbubble resonator (MBR) fabricated by a two-CO$_2$ laser beam technique. By decreasing the wall thickness of the MBR down to 1.4 $\\mu$m, the zero dispersion wavelength shifts to values shorter than 764 nm, making phase matching possible around 765 nm. With the optical \\textit{Q}-factor of the MBR modes being greater than $10^7$, four-wave mixing is observed at 765 nm for a pump power of 3 mW. By increasing the pump power, parametric oscillation is achieved, and a frequency comb with 14 comb lines is generated at visible wavelengths.

  10. Generation of 12 fs deep-ultraviolet pulses by four-wave mixing through filamentation in neon gas.

    Science.gov (United States)

    Fuji, Takao; Horio, Takuya; Suzuki, Toshinori

    2007-09-01

    Generation of deep-ultraviolet femtosecond pulses by four-wave mixing through filamentation in neon gas was demonstrated. Fundamental (omega) and second-harmonic (2omega) pulses of 25 fs Ti:sapphire amplifier output were focused into neon gas, and 20 microJ pulses with the center wavelength of 260 nm were produced by a four-wave mixing process, 2omega+2omega-omega?3omega through an ~15 cm filament. Additionally, pulses with an energy of 2 microJ at 200 nm were generated, probably by a cascaded process, 3omega+2omega-omega?4omega. The 260 nm pulses were compressed by a grating-based compressor and characterized by a dispersion-free transient grating frequency-resolved optical gating. The estimated pulse width was 12 fs.

  11. Phase conjugation of vector fields by degenerate four-wave mixing in a Fe-doped LiNbO₃.

    Science.gov (United States)

    Qian, Sheng-Xia; Li, Yongnan; Kong, Ling-Jun; Tu, Chenghou; Wang, Hui-Tian

    2014-08-15

    We propose a method to generate the phase-conjugate wave of the vector field by degenerate four-wave mixing in a c-cut Fe-doped LiNbO3 crystal. We demonstrate experimentally that the phase-conjugate wave of the vector field can be generated. In particular, the phase-conjugate vector field has also the peculiar function of compensating the polarization distortion, as the traditional phase-conjugate scaler field can compensate the phase distortion.

  12. High-Energy Four-Wave Mixing, with Large-Mode-Area Higher-Order Modes in Optical Fibres

    DEFF Research Database (Denmark)

    Rishøj, Lars Søgaard; Steinvurzel, P. E.; Chen, Y.

    2012-01-01

    We demonstrate, for the first time, four-wave mixing, in the 1-μm spectral regime, in an LMA silica fiber. Pumping a 618-μm2 LP07 mode (λo = 1038.4 nm) with a 1064.6-nm Nd:YAG laser results in the generation of modulation instability, and multiple Stokes/anti-Stokes lines, opening up the prospect...

  13. Controllable steep dispersion with gain in a four-level N-scheme with four-wave mixing

    Science.gov (United States)

    Phillips, Nathaniel B.; Novikova, Irina; Mikhailov, Eugeniy E.; Budker, Dmitry; Rochester, Simon

    2013-01-01

    We present a theoretical analysis of the propagation of light pulses through a medium of four-level atoms, with two strong pump fields and a weak probe field in an N-scheme arrangement. We show that four-wave mixing has a profound effect on the probe-field group velocity and absorption, allowing the probe-field propagation to be tuned from superluminal to slow-light regimes with amplification.

  14. Simulation of pattern and defect detection in periodic amplitude and phase structures using photorefractive four-wave mixing

    Science.gov (United States)

    Nehmetallah, Georges; Banerjee, Partha; Khoury, Jed

    2015-03-01

    The nonlinearity inherent in four-wave mixing in photorefractive (PR) materials is used for adaptive filtering. Examples include script enhancement on a periodic pattern, scratch and defect cluster enhancement, periodic pattern dislocation enhancement, etc. through intensity filtering image manipulation. Organic PR materials have large space-bandwidth product, which makes them useful in adaptive filtering techniques in quality control systems. For instance, in the case of edge enhancement, phase conjugation via four-wave mixing suppresses the low spatial frequencies of the Fourier spectrum of an aperiodic image and consequently leads to image edge enhancement. In this work, we model, numerically verify, and simulate the performance of a four wave mixing setup used for edge, defect and pattern detection in periodic amplitude and phase structures. The results show that this technique successfully detects the slightest defects clearly even with no enhancement. This technique should facilitate improvements in applications such as image display sharpness utilizing edge enhancement, production line defect inspection of fabrics, textiles, e-beam lithography masks, surface inspection, and materials characterization.

  15. Kinetic Temperature and Electron Density Measurement in an Inductively Coupled Plasma Torch using Degenerate Four-Wave Mixing

    Science.gov (United States)

    Schafer, Julia; Lyons, Wendy; Tong, WIlliam G.; Danehy, Paul M.

    2008-01-01

    Laser wave mixing is presented as an effective technique for spatially resolved kinetic temperature measurements in an atmospheric-pressure radio-frequency inductively-coupled plasma. Measurements are performed in a 1 kW, 27 MHz RF plasma using a continuous-wave, tunable 811.5-nm diode laser to excite the 4s(sup 3)P2 approaches 4p(sup 3)D3 argon transition. Kinetic temperature measurements are made at five radial steps from the center of the torch and at four different torch heights. The kinetic temperature is determined by measuring simultaneously the line shape of the sub-Doppler backward phase-conjugate degenerate four-wave mixing and the Doppler-broadened forward-scattering degenerate four-wave mixing. The temperature measurements result in a range of 3,500 to 14,000 K+/-150 K. Electron densities measured range from 6.1 (+/-0.3) x 10(exp 15)/cu cm to 10.1 (+/-0.3) x 10(exp 15)/cu cm. The experimental spectra are analyzed using a perturbative treatment of the backward phase-conjugate and forward-geometry wave-mixing theory. Stark width is determined from the collisional broadening measured in the phase-conjugate geometry. Electron density measurements are made based on the Stark width. The kinetic temperature of the plasma was found to be more than halved by adding deionized water through the nebulizer.

  16. Analysis of power-dependent phase-matched four-wave mixing in dispersion-managed transmission systems.

    Science.gov (United States)

    Gao, Shiming; Yang, Changxi; Jin, Guofan

    2003-12-20

    We investigate power-dependent phase-matched four-wave mixing (FWM) in wavelength division multiplexing transmission lines, in which positive and negative dispersion fibers are alternately arranged to manage the dispersion and the dispersion slope. The FWM effect shows power-independent phase matching when the channel power is low. However, it is power dependent at high power. The maximum FWM conversion efficiency is shifted away from the zero channel space in the case of power-dependent phase matching. Optimization of the dispersion system for suppression of the FWM effect is determined.

  17. Stimulated emission pumping of NH in flames by using two-color resonant four-wave mixing

    Energy Technology Data Exchange (ETDEWEB)

    Radi, P.P.; Frey, H.M.; Mischler, B.; Tzannis, A.P.; Beaud, P.; Gerber, T. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    In this work we examine the analytical potential of two-color resonant four-wave mixing for the determination and characterization of trace elements in a combustion environment. Experimental results for NH in flames at atmospheric pressure are presented. The selectivity of the technique is used to simplify the Q-branch region of the (0-0)A{sup 3}{Pi}-X{sup 3}{Sigma} vibronic transition of NH. In addition, we demonstrate that the technique is sensitive to state changing collisions. (author) 2 figs., 5 refs.

  18. Upconversion enhanced degenerate four-wave mixing in the mid-infrared for sensitive detection of acetylene in gas flows

    DEFF Research Database (Denmark)

    Høgstedt, Lasse; Dam, Jeppe Seidelin; Sahlberg, Anna-Lena

    2014-01-01

    We present a new background free method for in situ gas detection that combines degenerate four-wave mixing with an infra-red light detector based on parametric frequency upconversion of infra-red light. The system is demonstrated at mid infrared wavelengths for low concentration measurements...... of acetylene diluted in a N2 gas flow at ambient conditions. It is demonstrated that the system is able to cover more than 100 nm in scanning range and detect concentrations as low as 3 ppm based on the R9e line. A major issue in small signal measurements is scattered light and it is showed how a spatial...

  19. Highly sensitive and simple method for refractive index sensing of liquids in microstructured optical fibers using four-wave mixing

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch; Stefani, Alessio; Bang, Ole

    2011-01-01

    We present both experimental measurements and simulations for a simple fiber-optical liquid refractive index sensor, made using only commercially available components and without advanced postprocessing of the fiber. Despite the simplicity, we obtain the highest sensitivity experimentally...... demonstrated to date for aqueous solutions (refractive index around 1.33), which is relevant for extensions to biosensing. The sensor is based on measuring the spectral shift of peaks arising from four-wave mixing (FWM), when filling the holes of a microstructured fiber with different liquid samples...

  20. Time-resolved four-wave mixing in InAs/InGaAs quantum-dot amplifiers under electrical injection

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang Werner; Hvam, Jørn Märcher

    2000-01-01

    Time-resolved four-wave mixing in an InAs/InGaAs/GaAs electrically pumped quantum-dot amplifier is measured at room temperature for different applied bias currents going from optical absorption to gain of the device. The four-wave mixing signal from 140 fs pulses shows a transition from a delayed...... photon-echo response in the absorption regime to a prompt free polarization decay in the gain regime. This corresponds to a pronounced reduction of the dephasing time from 250 fs at zero bias to less than 50 fs at the maximum applied current. The four-wave mixing response at transparency of the device...

  1. Tunable, multiwavelength Tm-doped fiber laser based on polarization rotation and four-wave-mixing effect.

    Science.gov (United States)

    Wang, Xiong; Zhu, Yadong; Zhou, Pu; Wang, Xiaolin; Xiao, Hu; Si, Lei

    2013-11-04

    We propose and demonstrate a tunable multiwavelength fiber laser employing polarization-maintaining Tm-doped fiber based on polarization rotation and four-wave-mixing effect. Polarization-maintaining Tm-doped fiber and polarization controllers were employed to manipulate the polarization modes in the laser, and 400 m long single-mode passive fiber was used to enhance the four-wave-mixing effect and suppress the polarization mode competition. Stable fiber laser operation of 1-6 wavelengths around 1.9 μm was achieved at room temperatures. The wavelengths can be tuned through adjusting the polarization controllers. The optical signal-to-noise ratio of the laser is more than 31 dB. The wavelength shift is less than 0.05 nm and the peak fluctuation of each wavelength is analyzed. For most of the wavelengths the peak fluctuations are less than 3 dB and the peak fluctuations of wavelengths with more stability are below 1.5 dB.

  2. Analysis of third harmonic generation and four wave mixing in gold nanostructures by nonlinear finite difference time domain.

    Science.gov (United States)

    Sasanpour, Pezhman; Shahmansouri, Afsaneh; Rashidian, Bizhan

    2010-11-01

    Third order nonlinear effects and its enhancement in gold nanostructures has been numerically studied. Analysis method is based on computationally solving nonlinear Maxwell's equations, considering dispersion behavior of permittivity described by Drude model and third order nonlinear susceptibility. Simulation is done by method of nonlinear finite difference time domain method, in which nonlinear equations of electric field are solved by Newton-Raphshon method. As the main outcomes of third order nonlinear susceptibility, four wave mixing and third harmonic generation terms are produced around gold nanostructures. Results of analysis on different geometries and structures show that third order nonlinearity products are more enhanced in places where electric field enhancement is occurred due to surface plasmons. Results indicates that enhancement of nonlinearities is strongly occurred in structures whose interface is dielectric. According to analysis results, nonlinear effects are highly concentrated in the vicinity of nanostructures. Hence this approach can be used in applications where localized ultraviolet light is required.

  3. A novel approach to photonic generate microwave signals based on optical injection locking and four-wave mixing

    Science.gov (United States)

    Zhu, Huatao; Wang, Rong; Xiang, Peng; Pu, Tao; Fang, Tao; Zheng, Jilin; Li, Yuandong

    2017-10-01

    In this paper, a novel approach for photonic generation of microwave signals based on frequency multiplication using an injected distributed-feedback (DFB) semiconductor laser is proposed and demonstrated by a proof-of-concept experiment. The proposed system is mainly made up of a dual-parallel Mach-Zehnder modulator (DPMZM) and an injected DFB laser. By properly setting the bias voltage of the DPMZM, ±2-order sidebands with carrier suppression are generated, which are then injected into the slave laser. Due to the optical sideband locking and four-wave mixing (FWM) nonlinearity in the slave laser, new sidebands are generated. Then these sidebands are sent to an optical notch filter where all the undesired sidebands are removed. Finally, after photodetector detection, frequency multiplied microwave signals can be generated. Thanks to the flexibility of the optical sideband locking and FWM, frequency octupling, 12-tupling, 14-tupling and 16-tupling can be obtained.

  4. Polarization-insensitive 640 Gb/s demultiplexing based on four wave mixing in a polarization-maintaining fibre loop

    DEFF Research Database (Denmark)

    Hu, Hao; Mulvad, Hans Christian Hansen; Galili, Michael

    2010-01-01

    Polarization-insensitive 640 Gbit/s demultiplexing for OTDM data signals is demonstrated using a 100 m polarization-maintaining highly non-linear fibre. The scheme is based on four wave mixing (FWM) in a polarization-maintaining fibre loop (PMFL) with bidirectional operation. Less than 0.2 d......B polarization dependence is obtained. The FWM efficiency is about -6 dB if the passive loss of the PMFL is not included. The flatness characteristic of the FWM efficiencies allows for the OTDM demultiplexing of a high speed signal with a bandwidth of 1.2 THz. Error free performance with low penalty...... for the demultiplexed 10 Gbit/s signal is achieved for the polarization scrambled 640 Gbit/s data signal. BER measurements and eye-diagrams show that the demultiplexed 10 Gbit/s signals with and without polarization scrambling have almost identical performance....

  5. Measurement of laser-induced molecular alignment in cold, low density targets using femtosecond degenerate four wave mixing

    Science.gov (United States)

    Ren, Xiaoming; Makhija, Varun; Kumarappan, Vinod

    2011-05-01

    A femtosecond degenerate four wave mixing (DFWM) technique for measuring the laser induced non-adiabatic alignment of asymmetric top molecules in a dilute gas jet is reported. The alignment is probed using three beams in a folded BOXCARS geometry. By generating the three beams using a physical mask in a single probe beam, automatic overlap in space and time is obtained. By scanning the pump-probe delay and measuring the background-free DFWM signal, the alignment of rotationally-cold and low-density molecular targets can be rapidly characterized. We demonstrate the technique by measuring the alignment low-density iodobenzene in a high-pressure helium jet. This scheme can also be used with arbitrarily-shaped aligning pulses and pulse sequences, and for a wide variety of molecules. This work is supported by the US Department of Energy.

  6. Nonlinear mode conversion for intermodal four-wave mixing Stokes and anti-Stokes in a multimode fiber

    Science.gov (United States)

    Pourbeyram, Hamed; Mafi, Arash

    2017-02-01

    In this paper we study, both experimentally and by theory, a new nonlinear dynamic in multimode optical fiber where intermodal four-wave mixing (IM-FWM) and Kerr-induced nonlinear mode coupling (NLC) are strongly interacting. We show that presence of phase-matched IM-FWM and strong nonlinear mode coupling results in an unprecedented saturable mode conversion in the FWM anti-Stokes beam. We investigate the evolution of modal conversion as a function of fiber length and show that the result of this novel nonlinear dynamic is a controllable, length independent mode conversion. Our theoretical calculations suggest that the converted anti-Stokes beam can also be amplified via IM-FWM. We observe a mode conversion with an efficiency as high as 90 percent.

  7. Dynamic analysis of optical soliton pair and four-wave mixing via Fano interference in multiple quantum wells

    Science.gov (United States)

    Yan, Wei; Qu, Junle; Niu, H. B.

    2014-08-01

    We perform a time-dependent analysis of the formation and stable propagation of an ultraslow optical soliton pair, and four-wave mixing (FWM) via tunable Fano interference in double-cascade type semiconductor multiple quantum wells (SMQWs). By using the probability amplitude method to describe the interaction of the system, we demonstrate that the electromagnetically induced transparency (EIT) can be controlled by Fano interference in the linear case and the strength of Fano interference has an important effect on the group velocity and amplitude of the soliton pair in the nonlinear case. Then, when the signal field is removed, the dynamic FWM process is analyzed in detail, and we find that the strength of Fano interference also has an important effect on the FWM’s efficiency: the maximum FWM efficiency is ~28% in appropriate conditions. The investigations are promising for practical applications in optical devices and optical information processing for solid systems.

  8. Low-noise mid-IR upconversion detector for improved IR-degenerate four-wave mixing gas sensing.

    Science.gov (United States)

    Høgstedt, Lasse; Dam, Jeppe Seidelin; Sahlberg, Anna-Lena; Li, Zhongshan; Aldén, Marcus; Pedersen, Christian; Tidemand-Lichtenberg, Peter

    2014-09-15

    We compare a nonlinear upconversion detector with a conventional cryogenic InSb detector for the detection of coherent infrared light showing near-shot-noise-limited performance in the upconversion system. The InSb detector is limited by dark noise, which results in a 500 times lower signal-to-noise ratio. The two detectors are compared for the detection of a coherent degenerate four-wave mixing (DFWM) signal in the mid-infrared, and applied to measure trace-level acetylene in a gas flow at atmospheric pressure, probing its fundamental rovibrational transitions. In addition to lower noise, the upconversion system provides image information of the signal, thus adding new functionality compared to standard point detection methods. We further show that the upconversion detector system can be implemented as a simple replacement of the cryogenic detector.

  9. Generation and Amplification of Tunable Multicolored Femtosecond Laser Pulses by Using Cascaded Four-Wave Mixing in Transparent Bulk Media

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2010-04-01

    Full Text Available We have reviewed the generation and amplification of wavelength-tunable multicolored femtosecond laser pulses using cascaded four-wave mixing (CFWM in transparent bulk media, mainly concentrating on our recent work. Theoretical analysis and calculations based on the phase-matching condition could explain well the process semi-quantitatively. The experimental studies showed: (1 as many as fifteen spectral up-shifted and two spectral down-shifted sidebands were obtained simultaneously with spectral bandwidth broader than 1.8 octaves from near ultraviolet (360 nm to near infrared (1.2 μm; (2 the obtained sidebands were spatially separated well and had extremely high beam quality with M2 factor better than 1.1; (3 the wavelengths of the generated multicolor sidebands could be conveniently tuned by changing the crossing angle or simply replacing with different media; (4 as short as 15-fs negatively chirped or nearly transform limited 20-fs multicolored femtosecond pulses were obtained when one of the two input beams was negatively chirped and the other was positively chirped; (5 the pulse energy of the sideband can reach a μJ level with power stability better than 1% RMS; (6 broadband two-dimensional (2-D multicolored arrays with more than ten periodic columns and more than ten rows were generated in a sapphire plate; (7 the obtained sidebands could be simultaneously spectra broadened and power amplified in another bulk medium by using cross-phase modulation (XPM in conjunction with four-wave optical parametric amplification (FOPA. The characterization showed that this is interesting and the CFWM sidebands generated by this novel method have good enough qualities in terms of power stability, beam quality, and temporal features suited to various experiments such as ultrafast multicolor time-resolved spectroscopy and multicolor-excitation nonlinear microscopy.

  10. Increasing the density of modes in an optical frequency comb by cascaded four-wave mixing in a nonlinear optical fiber

    Science.gov (United States)

    Karki, Khadga J.

    2017-10-01

    Here, it is shown that when two optical frequency combs with identical mode spacing but different offset frequencies copropagate through a nonlinear optical fiber, four-wave mixing between them generates new modes. Although the spacings between the new modes depend on the difference of the offset frequencies, they appear irregular because of the large number of possible four-wave-mixing processes. However, when the difference in the offset frequencies is an integer fraction of the mode spacing of the original combs, the cascaded four-wave mixing generates a new comb with a fixed mode spacing given by the difference in the offset frequencies. This process can be used to substantially increase the mode density of a frequency comb. The method can be used in conjunction with new sources of frequency combs, such as quantum cascade lasers and microresonators, which have large mode spacing of tens of GHz. Decreasing the mode spacing of such sources is likely to increase their applicability.

  11. Highly Efficient Four-Wave Mixing in an AlGaAs-On-Insulator (AlGaAsOI) Nano-Waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Ottaviano, Luisa; Semenova, Elizaveta

    2015-01-01

    We propose an AlGaAs-on-insulator platform for nonlinear integrated photonics. We demonstrate highly efficient four-wave mixing in a 3-mm long AlGaAs-on-insulator nanowaveguide. A conversion efficiency of -21.1 dB is obtained with only a 45-mW pump......We propose an AlGaAs-on-insulator platform for nonlinear integrated photonics. We demonstrate highly efficient four-wave mixing in a 3-mm long AlGaAs-on-insulator nanowaveguide. A conversion efficiency of -21.1 dB is obtained with only a 45-mW pump...

  12. Continuous Wave Phase-Sensitive Four-Wave Mixing in Silicon Waveguides With Reverse-Biased p-i-n Junctions

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Vukovic, Dragana; Gajda, A.

    2013-01-01

    Phase-sensitive four-wave mixing is experimentally demonstrated using continuous wave pumps in silicon waveguides with p-i-n junctions. The reverse biasing allows decreasing the free carrier lifetime, enabling a phase-sensitive extinction ratio in excess of 15 dB.......Phase-sensitive four-wave mixing is experimentally demonstrated using continuous wave pumps in silicon waveguides with p-i-n junctions. The reverse biasing allows decreasing the free carrier lifetime, enabling a phase-sensitive extinction ratio in excess of 15 dB....

  13. Non-Degenerate Four-Wave Mixing in a Silicon Nanowire and its Application for One-to-Six WDM Multicasting

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua

    2011-01-01

    We present WDM multicasting based on non-degenerate four-wave mixing in a silicon nanowire. A one-to-six phase-preserving wavelength multicasting of 10 Gb/s differential phase-shift-keying data is experimentally demonstrated with bit-error rate measurements.......We present WDM multicasting based on non-degenerate four-wave mixing in a silicon nanowire. A one-to-six phase-preserving wavelength multicasting of 10 Gb/s differential phase-shift-keying data is experimentally demonstrated with bit-error rate measurements....

  14. Superluminal pulse propagation and amplification without inversion of microwave radiation via four-wave mixing in superconducting phase quantum circuits

    Science.gov (United States)

    Amini Sabegh, Z.; Vafafard, A.; Maleki, M. A.; Mahmoudi, M.

    2015-08-01

    We study the interaction of the microwave fields with an array of superconducting phase quantum circuits. It is shown that the different four-level configurations i.e. cascade, N-type, diamond, Y-type and inverted Y-type systems can be obtained in the superconducting phase quantum circuits by keeping the third order of the Josephson junction potential expansion whereas by dropping the third order term, just the cascade configuration can be established. We study the propagation and amplification of a microwave field in a four-level cascade quantum system, which is realized in an array of superconducting phase quantum circuits. We find that by increasing the microwave pump tones feeding the system, the normal dispersion switches to the anomalous and the gain-assisted superluminal microwave propagation is obtained in an array of many superconducting phase quantum circuits. Moreover, it is demonstrated that the stimulated microwave field is generated via four-wave mixing without any inversion population in the energy levels of the system (amplification without inversion) and the group velocity of the generated pulse can be controlled by the external oscillating magnetic fluxes. We also show that in some special set of parameters, the absorption-free superluminal generated microwave propagation is obtained in superconducting phase quantum circuit system.

  15. Generation of octave-spanning supercontinuum by Raman-assisted four-wave mixing in single-crystal diamond.

    Science.gov (United States)

    Lu, Chih-Hsuan; Yang, Li-Fan; Zhi, Miaochan; Sokolov, Alexei V; Yang, Shang-Da; Hsu, Chia-Chen; Kung, A H

    2014-02-24

    An octave-spanning coherent supercontinuum is generated by non-collinear Raman-assisted four-wave mixing in single-crystal diamond using 7.7 fs laser pulses that have been chirped to about 420 fs in duration. The use of ultrabroad bandwidth pulses as input results in substantial overlap of the generated spectrum of the anti-Stokes sidebands, creating a phase-locked supercontinuum when all the sidebands are combined to overlap in time and space. The overall bandwidth of the generated supercontinuum is sufficient to support its compression to isolated few-to-single cycle attosecond transients. The significant spectral overlap of adjacent anti-Stokes sidebands allows the utilization of straight-forward spectral interferometry to test the relative phase coherence of the anti-Stokes outputs and is demonstrated here for two adjacent pairs of sidebands. The method can subsequently be employed to set the relative phase of the sidebands for pulse compression and for the synthesis of arbitrary field transients.

  16. Measurement of field-free alignment of jet-cooled molecules by nonresonant femtosecond degenerate four-wave mixing

    Science.gov (United States)

    Ren, Xiaoming; Makhija, Varun; Kumarappan, Vinod

    2012-03-01

    A femtosecond degenerate four-wave mixing (fs-DFWM) technique for probing the alignment of molecules is described. The rotational wave packet generated by a strong pump beam modulates the nonresonant third-order susceptibility of the gas and this modulation is observed using a noncollinear background-free setup. As a demonstration of the technique, we measure the alignment of a linear molecule (nitrogen), a symmetric top (benzene), and an asymmetric top (iodobenzene) in a supersonic jet. The measured signal is shown to agree well with calculations of the nonresonant third-order susceptibility from the solution of the time-dependent Schrödinger equation. The pump-DFWM measurement scheme can be used with dilute jet-cooled targets, allows arbitrary pump pulses to be used, and is rapid enough to be incorporated into a feedback optimization loop. The scheme can easily be made polarization-sensitive, indicating the possibility of measuring and optimizing three-dimensional alignment of asymmetric-top molecules.

  17. Single-step fabrication of scalable multimode quantum resources using four-wave mixing with a spatially structured pump

    Science.gov (United States)

    Wang, Hailong; Fabre, Claude; Jing, Jietai

    2017-05-01

    Multimode quantum resources or states, in which quantum correlations are shared and distributed among multiple parties, are important not only for fundamental tests of quantum effects but also for their numerous possible applications in quantum technologies, such as quantum imaging and quantum metrology. Here we demonstrate the single-step fabrication of a multimode quantum resource from four-wave mixing (FWM) process in hot Rb vapor using a spatially structured pump, which consists of a coherent combination of two tilted pump beams. During this FWM process, one probe beam is amplified, three conjugate and two new probe beams are generated. The measured degrees of the intensity squeezing for the four-beam case and six-beam case are around -4.1 ±0.1 dB and -4.7 ±0.1 dB, respectively. The generated multiple quantum correlated beams are naturally separated with distinct directions, which is crucial for sending them out to quantum nodes at different locations in quantum communication. Our scheme is compact, simple, phase insensitive, and easily scalable to larger number of quantum-correlated modes.

  18. Polarization rotation of light propagating through a medium with efficient four-wave mixing and cross-phase modulation

    Science.gov (United States)

    Sahoo, Sushree S.; Bhowmick, Arup; Mohapatra, Ashok K.

    2017-03-01

    We have studied the rotation of an elliptically polarized light propagating through thermal rubidium vapor with efficient four-wave mixing (FWM) and cross-phase modulation (XPM). These nonlinear processes are enhanced by Zeeman coherence within the degenerate sub-levels of the two-level atomic system. The elliptically polarized light with small ellipticity is considered as the superposition of a strong-linearly-polarized pump beam and a weak-orthogonal-polarized probe beam. The interference of the probe and the newly generated light field due to degenerate FWM and their gain in the medium due to a large XPM induced by the pump beam leads to the rotation of the elliptical polarized light. A theoretical analysis of the probe propagation through the nonlinear medium was used to explain the experimental observation and the fitting of the experimental data gives the estimates of the third-order non-linear susceptibilities associated with FWM and XPM. Our study can provide useful parameters for the generation of efficient squeezed vacuum states and squeezed polarization states of light. Furthermore our study finds application in controlling the diffraction of a linearly-polarized light beam traversing the medium.

  19. Determination of the electric field strength of filamentary DBDs by CARS-based four-wave mixing

    Science.gov (United States)

    Böhm, P.; Kettlitz, M.; Brandenburg, R.; Höft, H.; Czarnetzki, U.

    2016-10-01

    It is demonstrated that a four-wave mixing technique based on coherent anti-Stokes Raman spectroscopy (CARS) can determine the electric field strength of a pulsed-driven filamentary dielectric barrier discharge (DBD) of 1 mm gap, using hydrogen as a tracer medium in nitrogen at atmospheric pressure. The measurements are presented for a hydrogen admixture of 10%, but even 5% H2 admixture delivers sufficient infrared signals. The lasers do not affect the discharge by photoionization or by other radiation-induced processes. The absolute values of the electric field strength can be determined by the calibration of the CARS setup with high voltage amplitudes below the ignition threshold of the arrangement. This procedure also enables the determination of the applied breakdown voltage. The alteration of the electric field is observed during the internal polarity reversal and the breakdown process. One advantage of the CARS technique over emission-based methods is that it can be used independently of emission, e.g. in the pre-phase and in between two consecutive discharges, where no emission occurs at all.

  20. Wavelength-agile high-power sources via four-wave mixing in higher-order fiber modes.

    Science.gov (United States)

    Demas, J; Prabhakar, G; He, T; Ramachandran, S

    2017-04-03

    Frequency doubling of conventional fiber lasers in the near-infrared remains the most promising method for generating integrated high-peak-power lasers in the visible, while maintaining the benefits of a fiber geometry; but since the shortest wavelength power-scalable fiber laser sources are currently restricted to either the 10XX nm or 15XX nm wavelength ranges, accessing colors other than green or red remains a challenge with this schematic. Four-wave mixing using higher-order fiber modes allows for control of dispersion while maintaining large effective areas, thus enabling a power-scalable method to extend the bandwidth of near-infrared fiber lasers, and in turn, the bandwidth of potential high-power sources in the visible. Here, two parametric sources using the LP0,7 and LP0,6 modes of two step-index multi-mode fibers are presented. The output wavelengths for the sources are 880, 974, 1173, and 1347 nm with peak powers of 10.0, 16.2, 14.7, and 6.4 kW respectively, and ~300-ps pulse durations. The efficiencies of the sources are analyzed, along with a discussion of wavelength tuning and further power scaling, representing an advance in increasing the bandwidth of near-infrared lasers as a step towards high-peak-power sources at wavelengths across the visible spectrum.

  1. All-optical OTDM-to-WDM signal-format translation and OTDM add-drop functionality using bidirectional four wave mixing in semiconductor optical amplifier

    DEFF Research Database (Denmark)

    Buxens Azcoaga, Alvaro Juan; Poulsen, Henrik Nørskov; Clausen, Anders

    2000-01-01

    The authors report simultaneous demultiplexing and wavelength conversion of two 10Gbit/s channels from a 40Gbit/s OTDM signal using bidirectional four wave mixing in a single semiconductor optical amplifier. Simultaneous demultiplexing and clearing of a 10Gbit/s channel from the 40Gbit/s OTDM dat...

  2. All-optical wavelength multicasting with extinction ratio enhancement using pump-modulated four-wave mixing in a dispersion-flattened nonlinear photonic crystal fiber

    DEFF Research Database (Denmark)

    Chow, K.K.; Shu, Chester; Lin, Chinlon

    2006-01-01

    All optical wavelength multicasting at 4 x 10 Gb/s with extinction ratio enhancement has been demonstrated based on pump-modulated four-wave mixing in a nonlinear photonic crystal fiber. We show that the input signal wavelength can simultaneously convert to four different wavelengths, with a powe...

  3. QPSK-to-2×BPSK wavelength and modulation format conversion through phase-sensitive four-wave mixing in a highly nonlinear optical fiber

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Dalgaard, Kjeld; Lei, Lei

    2013-01-01

    A phase-sensitive four-wave mixing (FWM) scheme enabling the simultaneous conversion of the two orthogonal quadratures of an optical signal to different wavelengths is demonstrated for the first time under dynamic operation using a highly nonlinear optical fiber (HNLF) as the nonlinear medium...

  4. Hybrid imaging of fluorescently labeled cancer drugs and label-free four-wave mixing microscopy of cancer cells and tissues

    NARCIS (Netherlands)

    Krabbendam, Rick; Pool, Martin; de Vries, Liesbeth G.; Offerhaus, Herman L.; Herek, Jennifer L.; Otto, Cees

    Fluorescent labels are well suited as tracers for cancer drug monitoring. Identifying cellular target regions of these drugs with a high resolution is important to assess the working principle of a drug. We investigate the applications of label-free nonresonant four-wave mixing (NR-FWM) microscopy

  5. Effects of noninstantaneous nonlinear processes on photon-pair generation by spontaneous four-wave mixing

    DEFF Research Database (Denmark)

    Koefoed, Jacob Gade; Christensen, Jesper Bjerge; Rottwitt, Karsten

    2017-01-01

    -production rate depends weakly on the waveguide temperature, due to higher-order Raman scattering events, and more strongly on pump-pair frequency detuning. From the analytical model, a numerical scheme is derived, based on the well-known split-step method. This scheme allows computation of joint states where...

  6. One-to-six WDM multicasting of DPSK signals based on dual-pump four-wave mixing in a silicon waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua

    2011-01-01

    We present WDM multicasting based on dual-pump four-wave mixing in a 3-mm long dispersion engineered silicon waveguide. One-to-six phase-preserving WDM multicasting of 10-Gb/s differential phase-shiftkeying (DPSK) data is experimentally demonstrated with bit-error rate measurements. All the six...... multicast signals show error-free performance with power penalty less than 3.8 dB....

  7. Redistribution of pump power and impairments in gain-equalized distributed fiber Raman amplifiers due to four-wave mixing and parametric amplification

    OpenAIRE

    Soto, Marcelo A.; Olivares,Ricardo

    2008-01-01

    In this work, by using a comprehensive numerical model which rigorously describes the interaction between stimulated Raman scattering (SRS) and four-wave mixing (FWM), we verify that FWM processes, including depletion and parametric gain, generate a redistribution of pump power in distributed fiber Raman amplifiers (DFRAs). As a consequence of pump–pump FWM, several FWM components can be generated, which act as new sources of SRS for Raman pumping. Due to new SRS–FWM interactions, a redistrib...

  8. Effects of Temperature and Axial Strain on Four-Wave Mixing Parametric Frequencies in Microstructured Optical Fibers Pumped in the Normal Dispersion Regime

    Directory of Open Access Journals (Sweden)

    Javier Abreu-Afonso

    2014-10-01

    Full Text Available A study of the effect of temperature and axial strain on the parametric wavelengths produced by four-wave mixing in microstructured optical fibers is presented. Degenerate four-wave mixing was generated in the fibers by pumping at normal dispersion, near the zero-dispersion wavelength, causing the appearance of two widely-spaced four-wave mixing spectral bands. Temperature changes, and/or axial strain applied to the fiber, affects the dispersion characteristics of the fiber, which can result in the shift of the parametric wavelengths. We show that the increase of temperature causes the signal and idler wavelengths to shift linearly towards shorter and longer wavelengths, respectively. For the specific fiber of the experiment, the band shift at rates ­–0.04 nm/ºC and 0.3 nm/ºC, respectively. Strain causes the parametric bands to shift in the opposite way. The signal band shifted 2.8 nm/me and the idler -5.4 nm/me. Experimental observations are backed by numerical simulations.

  9. Role of the phase-matching condition in nondegenerate four-wave mixing in hot vapors for the generation of squeezed states of light

    Science.gov (United States)

    Turnbull, M. T.; Petrov, P. G.; Embrey, C. S.; Marino, A. M.; Boyer, V.

    2013-09-01

    Nondegenerate forward four-wave mixing in hot atomic vapors has been shown to produce strong quantum correlations between twin beams of light [McCormick , Opt. Lett.OPLEDP0146-959210.1364/OL.32.000178 32, 178 (2007)], in a configuration which minimizes losses by absorption. In this paper, we look at the role of the phase-matching condition in the trade-off that occurs between the efficiency of the nonlinear process and the absorption of the twin beams. To this effect, we develop a semiclassical model by deriving the atomic susceptibilities in the relevant double-Λ configuration and by solving the classical propagation of the twin-beam fields for parameters close to those found in typical experiments. These theoretical results are confirmed by a simple experimental study of the nonlinear gain experienced by the twin beams as a function of the phase mismatch. The model shows that the amount of phase mismatch is key to the realization of the physical conditions in which the absorption of the twin beams is minimized while the cross coupling between the twin beams is maintained at the level required for the generation of strong quantum correlations. The optimum is reached when the four-wave mixing process is not phase matched for fully resonant four-wave mixing.

  10. SOLUTION METHOD OF DYNAMIC ROUTING AND WAVE LENGTH ASSIGNMENT PROBLEM FOR WDM NETWORKS WITH TAKING INTO ACCOUNT FOUR-WAVE MIXING EFFECT

    Directory of Open Access Journals (Sweden)

    D. V. Ageyev

    2016-05-01

    Full Text Available The problem of dynamic route selection and wavelengths assignment in WDM networks is solved. This problem is important in WDM network management when requests are serviced for short-term connection installation and excess traffic is transferred. The proposed solution method is heuristic and is an improvement of the previously known method by taking into account the influence of four-wave mixing and using the new metric for finding the routes prospective for application. This makes it possible to reduce the probability of blocking calls during the connections at the average of 13% and the value of Q factor at 0.812.

  11. Generation of a phase-conjugate wave by degenerate four-wave mixing in an erythrosin-B-doped planar waveguide.

    Science.gov (United States)

    Miyanaga, S; Yamabayashi, T; Fujiwara, H

    1988-11-01

    A phase-conjugate wave (PCW) generated by degenerate four-wave mixing (DFWM) in a nonlinear-optical waveguide excited by a cw Ar-ion laser was observed. The planar waveguide consisted of a transparent polyvinyl alcohol layer partly doped with erythrosin-B. The DFWM excitation was performed as follows: Two pump waves impinged in the interaction region of the waveguide from the outside, and a probe wave was introduced into the guiding layer by a prism coupler. A PCW reflectivity of 6.3 x 10(-5) outside the prism coupler was obtained at a pump intensity of 1.2 W/cm(2).

  12. Pump-probe and Four-wave Mixing Spectra Arising from Recoil-induced Resonance in an Operating Cesium Magneto-Optical Trap

    Science.gov (United States)

    Ji, Zhonghua; Zhang, Hongshan; Su, Dianqiang; Zhao, Yanting; Xiao, Liantuan; Jia, Suotang

    2018-02-01

    We present experimental observation of recoil-induced resonance (RIR) in an operating cesium magneto-optical trap (MOT) by both pump-probe absorption and four-wave mixing spectra simultaneously. We investigate the dependence of amplitudes of these two spectra on pump beam intensity and frequency. The measurement results agree well with the recoil-induced theory with modifications of Raman transition effect and atomic number. The systematical study on RIR spectra is meaningful for the diagnostic measurement of cold atoms in an operating MOT.

  13. Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

    OpenAIRE

    Oleg A. Louchev; Norihito Saito; Yu Oishi; Koji Miyazaki; Kotaro Okamura; Jumpei Nakamura; Masahiko Iwasaki; Satoshi Wada

    2016-01-01

    We develop a set of analytical approximations for the estimation of the combined effect of various photoionization processes involved in the resonant four-wave mixing generation of ns pulsed Lyman-α (L-α) radiation by using 212.556 nm and 820-845 nm laser radiation pulses in Kr-Ar mixture: (i) multi-photon ionization, (ii) step-wise (2+1)-photon ionization via the resonant 2-photon excitation of Kr followed by 1-photon ionization and (iii) laser-induced avalanche ionization produced by genera...

  14. The first search for sub-eV scalar fields via four-wave mixing at a quasi-parallel laser collider

    CERN Document Server

    Homma, Kensuke; Kume, Kazuki

    2014-01-01

    A search for sub-eV scalar fields coupling to two photons has been performed via four-wave mixing at a quasi-parallel laser collider for the first time. The experiment demonstrates the novel approach to search for resonantly produced sub-eV scalar fields by combining two-color laser fields in the vacuum. The aim of this paper is to provide the concrete experimental setup and the analysis method based on specific combinations of polarization states between incoming and outgoing photons, which is extendable to higher intensity laser systems operated at high repetition rates. No significant signal of four-wave mixing was observed by combining a $0.2\\mu$J/0.75ns pulse laser and a 2mW CW laser on the same optical axis. Based on the prescription developed for this particular experimental approach, we obtained the upper limit at a confidence level of 95% on the coupling-mass relation.

  15. Mechanism and computational model for Lyman-α-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

    Science.gov (United States)

    Louchev, Oleg A.; Bakule, Pavel; Saito, Norihito; Wada, Satoshi; Yokoyama, Koji; Ishida, Katsuhiko; Iwasaki, Masahiko

    2011-09-01

    We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-α (Ly-α) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-α generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-α radiation generation can achieve a value of ˜5×10-4 which is restricted by the total combined absorption of the fundamental and generated radiation.

  16. All-optical ultrafast wavelength and mode converter based on inter-modal four-wave mixing in few-mode fibers

    Science.gov (United States)

    Weng, Yi; He, Xuan; Wang, Junyi; Pan, Zhongqi

    2015-08-01

    An ultrafast all-optical simultaneous wavelength and mode conversion scheme is purposed based on intermodal four-wave mixing (IM-FWM), with the capability of switching state of polarization (SOP) and mode degeneracy orientation (MDO) in few-mode fibers (FMF). The relation among the conversion efficiency, pump power and phase matching conditions is investigated in theory analysis and simulation. Using this scheme, cross-polarization modulation (XPolM) and cross-mode modulation (XMM) can be achieved, by in the best case up to 50% conversion efficiency. Furthermore, numerical results further indicate that the proposed configuration has the potential application for generating doughnut modes by the mixing of three characteristic spatial frequencies.

  17. Non-degenerate four-wave mixing in an optically injection-locked InAs/InP quantum dot Fabry–Perot laser

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.; Schires, K.; Grillot, F. [Télécom ParisTech, Ecole Nationale Supérieure des Télécommunications, CNRS LTCI, 46 rue Barrault, 75013 Paris Cedex (France); Poole, P. J. [National Research Council Canada, 1200 Montreal Road, Ottawa, Ontario K1A 0R6 (Canada)

    2015-04-06

    Non-degenerate four-wave mixing in an InAs/InP quantum dot Fabry–Perot laser is investigated with an optical injection-locking scheme. Wavelength conversion is obtained for frequency detunings ranging from +2.5 THz to −3.5 THz. The normalized conversion efficiency is maintained above −40 dB between −1.5 and +0.5 THz with an optical signal-to-noise ratio above 20 dB and a maximal third-order nonlinear susceptibility normalized to material gain of 2 × 10{sup −19} m{sup 3}/V{sup 2}. In addition, we show that injection-locking at different positions in the gain spectrum has an impact on the nonlinear conversion process and the symmetry between up- and down- converted signals.

  18. Four-wave mixing and octave-spanning supercontinuum generation in a small core hydrogenated amorphous silicon fiber pumped in the mid-infrared.

    Science.gov (United States)

    Shen, L; Healy, N; Xu, L; Cheng, H Y; Day, T D; Price, J H V; Badding, J V; Peacock, A C

    2014-10-01

    An octave-spanning supercontinuum is generated in a hydrogenated amorphous silicon core fiber when pumped in the mid-infrared regime. The broadband wavelength conversion which extends from the edge of the telecommunications band into the mid-infrared (1.64-3.37 μm) is generated by four-wave mixing (FWM) and subsequent pulse break-up, facilitated by the high material nonlinear figure of merit and the anomalous dispersion of the relatively small 1.7 μm diameter core fiber. The FWM sidebands and corresponding supercontinuum can be tuned through the pump parameters, and show good agreement with the predicted phase-matching curves for the fiber.

  19. Dynamically controlled two-color photonic band gaps via balanced four-wave mixing in one-dimensional cold atomic lattices

    Science.gov (United States)

    Yang, Hong; Yang, Liu; Wang, Xiao-Chang; Cui, Cui-Li; Zhang, Yan; Wu, Jin-Hui

    2013-12-01

    We study an ensemble of cold atoms driven to the four-level double-Λ configuration and trapped in the one-dimensional optical lattices for achieving dynamically controlled photonic band gaps (PBGs) via the balanced four-wave mixing interaction. Numerical results show that a pair of PBGs characterized by high platforms of probe reflectivities and reduced density of photonic states are established, simultaneously, on both probe transitions in one symmetric driving scheme. Such two-color PBGs can be easily manipulated in position and width by modulating, e.g., the balanced Rabi frequencies of two coupling fields and the Gaussian widths of atomic density distributions, to change the equal probe detunings fulfilling both Bragg conditions. Each two-color PBG as predicted in the coherent atomic lattices may be explored to attain robust light entanglement, even for single-probe photons, via an efficient frequency conversion during the nonlinearly correlated reflection.

  20. Performance investigation of suppression of four wave mixing using optical phase conjugation with different modulation format in DWDM soliton communication system

    Science.gov (United States)

    Kaur, G.; Kaler, R. S.; Singh, S.

    2017-03-01

    The performance of dense wavelength division multiplexed (DWDM) soliton transmission system for returnto-zero (RZ) and non-return-to-zero (NRZ) modulation formats have been investigated. The main aim of this paper is to estimate and mitigate the four wave mixing (FWM) power by using in-line optical phase conjugator (OPC). The effect of FWM has been estimated using real fiber link having nonlinear and attenuation losses. The FWM power is strongly suppressed by introducing destructive interference between the first and second halves of in-line OPC. It has been indicated that RZ with OPC yields the better performance with FWM power suppression (more than 20 dBm in certain cases) with reasonable bit error rate and Q-factor.

  1. Simultaneous multichannel wavelength multicasting and XOR logic gate multicasting for three DPSK signals based on four-wave mixing in quantum-dot semiconductor optical amplifier.

    Science.gov (United States)

    Qin, Jun; Lu, Guo-Wei; Sakamoto, Takahide; Akahane, Kouichi; Yamamoto, Naokatsu; Wang, Danshi; Wang, Cheng; Wang, Hongxiang; Zhang, Min; Kawanishi, Tetsuya; Ji, Yuefeng

    2014-12-01

    In this paper, we experimentally demonstrate simultaneous multichannel wavelength multicasting (MWM) and exclusive-OR logic gate multicasting (XOR-LGM) for three 10Gbps non-return-to-zero differential phase-shift-keying (NRZ-DPSK) signals in quantum-dot semiconductor optical amplifier (QD-SOA) by exploiting the four-wave mixing (FWM) process. No additional pump is needed in the scheme. Through the interaction of the input three 10Gbps DPSK signal lights in QD-SOA, each channel is successfully multicasted to three wavelengths (1-to-3 for each), totally 3-to-9 MWM, and at the same time, three-output XOR-LGM is obtained at three different wavelengths. All the new generated channels are with a power penalty less than 1.2dB at a BER of 10(-9). Degenerate and non-degenerate FWM components are fully used in the experiment for data and logic multicasting.

  2. Observation of the exciton and Urbach band tail in low-temperature-grown GaAs using four-wave mixing spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Webber, D.; Yildirim, M.; Hacquebard, L.; March, S.; Mathew, R.; Gamouras, A.; Hall, K. C. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2 (Canada); Liu, X.; Dobrowolska, M.; Furdyna, J. K. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2014-11-03

    Four-wave mixing (FWM) spectroscopy reveals clear signatures associated with the exciton, free carrier inter-band transitions, and the Urbach band tail in low-temperature-grown GaAs, providing a direct measure of the effective band gap as well as insight into the influence of disorder on the electronic structure. The ability to detect (and resolve) these contributions, in contrast to linear spectroscopy, is due to an enhanced sensitivity of FWM to the optical joint density of states and to many-body effects. Our experiments demonstrate the power of FWM for studying the near-band-edge optical properties and coherent carrier dynamics in low-temperature-grown semiconductors.

  3. Perturbation Facilitated Optical Optical Double Resonance Investigation of the Quintet Manifold of C_2 by Applying Two-Color Four-Wave Mixing

    Science.gov (United States)

    Bornhauser, Peter; Marquardt, Roberto; Radi, Peter

    2014-06-01

    The potential of four-wave mixing spectroscopy for deperturbation studies has been demonstrated by an analysis of the spin-orbit and L-uncoupling interaction between the d ^3Π_g,v=4 and the b ^3Σ_g^-, v=16 states of C_2. The double-resonance method provides unambiguous assignments of perturbed transitions by intermediate level labeling. Furthermore, the sensitivity of the method unveiled extra transitions that originate from the perturbing b ^3Σ_g^-, v=16 state. A following study has successfully applied the method to deperturb the d ^3Π_g,v=6 state of the dicarbon and lead to the discovery of the first high-spin state of C_2. The energetically lowest quintet (^5Π_g) %and the additionally perturbing b ^3Σ_g^-, v=19 state% has been characterized by applying a conventional Hamiltonian. The detailed study unraveled major issues of the so-called high-pressure band of C_2 which were initially observed back in 1910 and later observed in numerous experimental environments. In this work we take into account our recent studies on tri-carbon where we used perturbation-facilitated two-color resonant four-wave mixing spectroscopy to access the (dark) triplet manifold of C_3 from the singlet tilde{X}^1Σ_g^+ ground state via ``gate-way" levels (i.e. singlet-triplet mixed levels). In a similar way, we performed for this study perturbation-facilitated optical-optical double-resonance experiments to access the first excited quintet state of C_2 via ``gate-way states" in the perturbed d ^3Π_g,v=6. The newly found ^5Π_u state is characterized at rotational resolution by performing a least-squares fit of the observed transitions to a ^5Π_u - ^5Π_g Hamiltionian. The work represents a rare case of a successful analysis of a quintet manifold of a molecule exhibiting a singlet ground state (^1Σ_g^+). P. Bornhauser, G. Knopp, T. Gerber, and P.P. Radi, Journal of Molecular Spectroscopy 262, 69 (2010). P. Bornhauser, Y. Sych, G. Knopp, T. Gerber, and P.P. Radi, J. Chem. Phys. 134

  4. An all-optical frequency up-converter utilizing four-wave mixing in a semiconductor optical amplifier for sub-carrier multiplexed radio-over-fiber applications.

    Science.gov (United States)

    Kim, Hyoung-Jun; Song, Jong-In; Song, Ho-Jin

    2007-03-19

    A novel all-optical frequency up-converter utilizing four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) was proposed and experimentally demonstrated. The frequency up-converter converted an optical intermediate frequency (IF) signal (f(IF) = 2.5 GHz) to an optical radio frequency (RF) signal (f(RF) = 35 and 40 GHz) through mixing with an optical local oscillator (LO) signal (f(LO) = 37.5 GHz). The up-converter showed positive conversion efficiency of 5.77 dB for the optical IF power of -22 dBm and the optical LO power of -13 dBm. This scheme showed broad bandwidths with respect to both LO and IF frequencies. The up-converter showed a phase noise of -84.5 dBc/Hz for the LO frequency of 37.5 GHz (f(LO)) and the offset frequency of 10 kHz after the frequency up-conversion.

  5. A C- and L-band dual-wavelength erbium-doped fibre laser for assisting four-wave mixing self-stability

    Science.gov (United States)

    Liu, Xueming; Zhao, Wei; Liu, Hongjun; Zou, Kuaisheng; Zhang, Tongyi; Lu, Keqing; Sun, Chuandong; Wang, Yishan; Ouyang, Xian; Chen, Guofu; Hou, Xun

    2006-06-01

    A kind of photonic 'Robin Hood' based on four-wave mixing is proposed and proved to be effective, theoretically and experimentally, in detail. Its applications for L-band dual-wavelength erbium-doped fibre (EDF) laser use are experimentally demonstrated at room temperature. The experimental results show that the conventional EDF cavity only induces a very unstable L-band laser, but the novel Robin Hood can effectively suppress the homogeneous gain in the erbium laser. By using suitable fibre Bragg gratings and stretching them, the proposed EDF laser can operate from ~1520 to ~1635 nm, so our dual-wavelength EDF laser can be used in lasing operation not only for the L band but also for the C band. The outstanding merits of our dual-wavelength laser are the flexible tuning and the ultrabroad spectral range of more than 115 nm. The experimental results show that the stability and uniformity of the proposed dual-wavelength laser in C-band operation are better than those for the same laser in L-band operation.

  6. Background-Free 3D Nanometric Localization and Sub-nm Asymmetry Detection of Single Plasmonic Nanoparticles by Four-Wave Mixing Interferometry with Optical Vortices

    Science.gov (United States)

    Zoriniants, George; Masia, Francesco; Giannakopoulou, Naya; Langbein, Wolfgang; Borri, Paola

    2017-10-01

    Single nanoparticle tracking using optical microscopy is a powerful technique with many applications in biology, chemistry, and material sciences. Despite significant advances, localizing objects with nanometric position precision in a scattering environment remains challenging. Applied methods to achieve contrast are dominantly fluorescence based, with fundamental limits in the emitted photon fluxes arising from the excited-state lifetime as well as photobleaching. Here, we show a new four-wave-mixing interferometry technique, whereby the position of a single nonfluorescing gold nanoparticle of 25-nm radius is determined with 16 nm precision in plane and 3 nm axially from rapid single-point measurements at 1-ms acquisition time by exploiting optical vortices. The precision in plane is consistent with the photon shot-noise, while axially it is limited by the nano-positioning sample stage, with an estimated photon shot-noise limit of 0.5 nm. The detection is background-free even inside biological cells. The technique is also uniquely sensitive to particle asymmetries of only 0.5% ellipticity, corresponding to a single atomic layer of gold, as well as particle orientation. This method opens new ways of unraveling single-particle trafficking within complex 3D architectures.

  7. Experimental observation of multi-spatial-mode quantum correlations in four-wave mixing with a conical pump and a conical probe

    Science.gov (United States)

    Du, Jinjian; Cao, Leiming; Zhang, Kai; Jing, Jietai

    2017-06-01

    Extensive attention has been drawn in generating multimode quantum states in recent years. Many efforts have been made during the last decade to produce such states. In this paper, we have experimentally demonstrated a scheme for generating a multi-spatial-mode quantum light source by a non-degenerated four-wave mixing process with a conical pump and a conical probe in a hot atomic vapor cell. The degree of the intensity-difference squeezing between the generated twin beams is about -4.1 dB. Due to the similar conical shape of the concentric quantum correlated beams, both the amplified probe and the generated conjugate beams can be decomposed into many angular modes. We have also experimentally verified the multi-spatial-mode nature of the generated quantum correlation by comparing the noise levels' variation tendencies of global attenuation and local cutting attenuations. In addition, we have also found the optimal values of each parameter in this scheme for further applications. Due to our scheme's advantages such as compactness, phase-insensitivity, and easy scalability, we have already shown a promising candidate for generating multi-spatial-mode quantum states, which may find potential applications in quantum metrology and quantum imaging, such as quantum-enhanced superresolution and the generation of multiple quantum correlated images.

  8. Novel Raman Parametric Hybrid L-Band Amplifier with Four-Wave Mixing Suppressed Pump for Terabits Dense Wavelength Division Multiplexed Systems

    Directory of Open Access Journals (Sweden)

    Gaganpreet Kaur

    2016-01-01

    Full Text Available We demonstrate improved performance of parametric amplifier cascaded with Raman amplifier for gain of 54.79 dB. We report amplification of L-band using 100 × 10 Gbps Dense Wavelength Division Multiplexed (DWDM system with 25 GHz channel spacing. The gain achieved is the highest reported so far with gain flatness of 3.38 dB without using any gain flattening technique. Hybrid modulated parametric pump is used for suppressing four-wave mixing (FWM around pump region, resulting in improvement of gain flatness by 2.42 dB. The peak to peak variation of gain is achieved less than 1.6 dB. DWDM system with 16-channel, 25 GHz spaced system has been analyzed thoroughly with hybrid modulated parametric pump amplified Raman-FOPA amplifier for gain flatness and improved performance in terms of BER and Q-factor.

  9. Analysis of Signal-to-Crosstalk Ratio Variations due to Four-Wave Mixing in Dense Wavelength Division Multiplexing Systems Implemented with Standard Single-Mode Fibers

    Directory of Open Access Journals (Sweden)

    Sait Eser KARLIK

    2016-10-01

    Full Text Available In this paper, variation of the signal-to-crosstalk ratio (SXR due to effects of four-wave mixing (FWM has been analyzed on center channels of 5-, 7-, 9-channel dense wavelength division multiplexing (DWDM systems implemented with G.652 standard single-mode fibers (SSMFs for 12.5 GHz, 25 GHz, 50 GHz and 100 GHz equal channel spacing values. Center channels on such systems are the most severely impacted channels by FWM. Therefore, results obtained are the worst-case values for the DWDM system performance and important for system design. Simulations have been performed for systems using three different commercially available SMFs having different design parameter values for chromatic dispersion, dispersion slope, nonlinearity coefficient and attenuation coefficient which are all in the scope of the G.652 Recommendation of Telecommunication Standardization Sector of International Telecommunication Union (ITU-T for SSMFs. In those simulations, under the impact of FWM, variation of SXR with variations in input powers, channel spacings and link lengths have been observed. Simulation results display the combined effect of the optical fiber and system design parameters on FWM performance of DWDM systems and give important clues for not only long-haul but also access network implementations of DWDM systems.

  10. Coherent wavepacket motion in an ultrafast electron transfer system monitored by femtosecond degenerate four-wave-mixing and pump–probe spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nagasawa, Yutaka, E-mail: nagasawa@chem.es.osaka-u.ac.jp [Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Center for Quantum Science and Technology under Extreme Conditions, Osaka University, Toyonaka, Osaka 560-8531 (Japan); PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); Yoneda, Yusuke; Nambu, Shohei; Muramatsu, Masayasu; Takeuchi, Eisuke; Tsumori, Hiroki; Morikawa, Soichiro [Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Katayama, Tetsuro [PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); Miyasaka, Hiroshi [Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Center for Quantum Science and Technology under Extreme Conditions, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

    2014-10-17

    Highlights: • Coherent wavepacket motion was investigated for ultrafast electron transfer (ET) system. • Vibrations originating from ground and excited states were extracted with high accuracy. • The dephasing of the excited state vibration was accelerated by the ultrafast ET. - Abstract: Coherent nuclear wavepacket motions were monitored by three types of femtosecond time-resolved spectroscopy, namely, transient absorption measurement utilizing white-light supercontinuum (WC-TA), degenerate four-wave-mixing (DFWM), and pump–probe (PP) measurements, for an ultrafast intermolecular electron transfer (ET) system with a dye molecule, oxazine 1 (Ox1), dissolved in an electron donating solvent, N,N-dimethylaniline (DMA). Vibrational frequencies of the wavepacket motion in the excited and in the ground states were 560–562 and 567–569 cm{sup −1}, respectively, with only a few frequency difference of 5–9 cm{sup −1}, which were clearly distinguishable by the highly accurate measurements. In DMA, the excited state wavepacket motion declined with time constant of 160–240 fs which is somewhat longer than that of the ultrafast ET; 60–80 fs.

  11. Deep-ultraviolet second-harmonic generation by combined degenerate four-wave mixing and surface nonlinearity polarization in photonic crystal fiber.

    Science.gov (United States)

    Yuan, Jinhui; Kang, Zhe; Li, Feng; Zhou, Guiyao; Zhang, Xianting; Mei, Chao; Sang, Xinzhu; Wu, Qiang; Yan, Binbin; Zhou, Xian; Zhong, Kangping; Wang, Kuiru; Yu, Chongxiu; Lu, Chao; Tam, Hwa Yaw; Wai, P K A

    2017-08-23

    Deep-ultraviolet (UV) second-harmonics (SHs) have important applications in basic physics and applied sciences. However, it still remains challenging to generate deep-UV SHs especially in optical fibers. Here, for the first time, we experimentally demonstrate the deep-UV SH generations (SHGs) by combined degenerate four-wave mixing (FWM) and surface nonlinearity polarization in an in-house designed and fabricated air-silica photonic crystal fiber (PCF). When femtosecond pump pulses with average input power P av of 650 mW and center wavelength λ p of 810, 820, 830, and 840 nm are coupled into the normal dispersion region close to the zero-dispersion wavelength of the fundamental mode of the PCF, the anti-Stokes waves induced by degenerate FWM process are tunable from 669 to 612 nm. Then, they serve as the secondary pump, and deep-UV SHs are generated within the wavelength range of 334.5 to 306 nm as a result of surface nonlinearity polarization at the core-cladding interface of the PCF. The physical mechanism of the SHGs is confirmed by studying the dependences of the output power P SH of the SHs on the PCF length and time. Finally, we also establish a theoretical model to analyze the SHGs.

  12. Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

    Science.gov (United States)

    Louchev, Oleg A.; Saito, Norihito; Oishi, Yu; Miyazaki, Koji; Okamura, Kotaro; Nakamura, Jumpei; Iwasaki, Masahiko; Wada, Satoshi

    2016-09-01

    We develop a set of analytical approximations for the estimation of the combined effect of various photoionization processes involved in the resonant four-wave mixing generation of ns pulsed Lyman-α (L-α ) radiation by using 212.556 nm and 820-845 nm laser radiation pulses in Kr-Ar mixture: (i) multi-photon ionization, (ii) step-wise (2+1)-photon ionization via the resonant 2-photon excitation of Kr followed by 1-photon ionization and (iii) laser-induced avalanche ionization produced by generated free electrons. Developed expressions validated by order of magnitude estimations and available experimental data allow us to identify the area for the operation under high input laser intensities avoiding the onset of full-scale discharge, loss of efficiency and inhibition of generated L-α radiation. Calculations made reveal an opportunity for scaling up the output energy of the experimentally generated pulsed L-α radiation without significant enhancement of photoionization.

  13. Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

    Directory of Open Access Journals (Sweden)

    Oleg A. Louchev

    2016-09-01

    Full Text Available We develop a set of analytical approximations for the estimation of the combined effect of various photoionization processes involved in the resonant four-wave mixing generation of ns pulsed Lyman-α (L-α radiation by using 212.556 nm and 820-845 nm laser radiation pulses in Kr-Ar mixture: (i multi-photon ionization, (ii step-wise (2+1-photon ionization via the resonant 2-photon excitation of Kr followed by 1-photon ionization and (iii laser-induced avalanche ionization produced by generated free electrons. Developed expressions validated by order of magnitude estimations and available experimental data allow us to identify the area for the operation under high input laser intensities avoiding the onset of full-scale discharge, loss of efficiency and inhibition of generated L-α radiation. Calculations made reveal an opportunity for scaling up the output energy of the experimentally generated pulsed L-α radiation without significant enhancement of photoionization.

  14. PUMP-PUMP FOUR-WAVE MIXING IN DISTRIBUTED FIBER RAMAN AMPLIFIERS MEZCLA DE CUATRO ONDAS ENTRE BOMBAS EN AMPLIFICADORES DE FIBRA RAMAN DISTRIBUIDOS

    Directory of Open Access Journals (Sweden)

    Marcelo Soto

    2007-08-01

    Full Text Available In this work, a comprehensive mathematical model which rigorously describes the interaction between stimulated Raman scattering (SRS and four-wave mixing (FWM in distributed fiber Raman amplifiers (DFRAs is presented. The parametric effects on DFRAs due to pump-pump FWM processes are completely characterized. Numerical simulations are contrasted with experimental measurements which were carried out with different configurations of DFRAs. The results validate the proposed mathematical model, which can be extended to include other non-linear effects. Finally, the pump-to-pump FWM effects on the spectral gain of a DFRA are analyzed.En este trabajo se presenta un modelo matemático que describe rigurosamente la interacción entre esparcimiento Raman estimulado (SRS y mezcla de cuatro ondas (FWM en amplificadores Raman distribuidos (DFRAs. Los efectos paramétricos ocurridos en DFRAs debido al proceso de FWM entre bombas, son completamente caracterizados. Los resultados de las simulaciones numéricas son contrastados con mediciones experimentales llevadas a cabo en diferentes configuraciones de DFRAs. Los resultados permiten validar el modelo matemático propuesto, el cual puede ser extendido para incluir otras no-linealidades. Finalmente, se analizan los efectos de FWM entre bombas en el comportamiento espectral de la ganancia de un DFRA.

  15. On the non-linear spectroscopy including saturated absorption and four-wave mixing in two and multi-level atoms: a computational study

    Science.gov (United States)

    Patel, M.; De Jager, G.; Nkosi, Z.; Wyngaard, A.; Govender, K.

    2017-10-01

    In this paper we report on the study of two and multi-level atoms interacting with multiple laser beams. The semi-classical approach is used to describe the system in which the atoms are treated quantum mechanically via the density matrix operator, while the laser beams are treated classically using Maxwells equations. We present results of a two level atom interacting with single and multiple laser beams and demonstrate Rabi oscillations between the levels. The effects of laser modulation on the dynamics of the atom (atomic populations and coherences) are examined by solving the optical Bloch equations. Plots of the density matrix elements as a function of time are presented for various parameters such as laser intensity, detuning, modulation etc. In addition, phase-space plots and Fourier analysis of the density matrix elements are provided. The atomic polarization, estimated from the coherence terms of the density matrix elements, is used in the numerical solution of Maxwells equations to determine the behaviour of the laser beams as they propagate through the atomic ensemble. The effects of saturation and hole-burning are demonstrated in the case of two counter propagating beams with one being a strong beam and the other being very weak. The above work is extended to include four-wave mixing in four level atoms in a diamond configuration. Two co-propagating beams of different wavelengths drive the atoms from a ground state |1〉 to an excited state |3〉 via an intermediate state |2〉. The atoms then move back to the ground state via another intermediate state |4〉, resulting in the generation of two additional correlated photon beams. The characteristics of these additional photons are studied.

  16. Generation of 3.6  μm radiation and telecom-band amplification by four-wave mixing in a silicon waveguide with normal group velocity dispersion.

    Science.gov (United States)

    Kuyken, B; Verheyen, P; Tannouri, P; Liu, X; Van Campenhout, J; Baets, R; Green, W M J; Roelkens, G

    2014-03-15

    Mid-infrared light generation through four-wave mixing-based frequency down-conversion in a normal group velocity dispersion silicon waveguide is demonstrated. A telecom-wavelength signal is down-converted across more than 1.2 octaves using a pump at 2190 nm in a 1 cm-long waveguide. At the same time, a 13 dB on-chip parametric gain of the telecom signal is obtained.

  17. 10 Gbps WDM transmission performance limits using in-line SOAs and an optical phase conjugator based on four-wave mixing in SOAs as a mid-span spectral inversion technique.

    Science.gov (United States)

    Hur, Sub; Kim, Yonggyou; Jang, Hodeok; Jeong, Jichai

    2006-05-29

    We have theoretically investigated the transmission performance limits of all semiconductor optical amplifiers (SOA)-based 10 Gb/s wavelength division multiplexing (WDM) systems using in-line SOAs and an optical phase conjugator (OPC) based on four-wave mixing in SOAs as a mid-span spectral inversion technique. With a verified numerical model of SOAs, we have found that the crosstalk from SOAs in OPC is a dominant factor to limit the number of channels in WDM systems. In order to increase the available number of channels, we optimize the input optical power and the injection current to SOAs in OPC with using a reservoir channel in in-line SOAs. All SOA-based 10 Gb/s WDM systems using the OPC can transmit 16 channel signals up to 240 km distance with a 3 dB power penalty.

  18. Geometric interpretation of four-wave mixing

    DEFF Research Database (Denmark)

    Ott, Johan Raunkjær; Steffensen, Henrik; Rottwitt, Karsten

    2013-01-01

    -like coordinates of the electric fields, which reduce the FWM dynamics to a closed two-dimensional surface, similar to the Bloch sphere of quantum electrodynamics or the Pointcare´ sphere in polarization dynamics. The coordinates are chosen so as to use the gauge invariance symmetries of the FWM equations which...... also give the conservation of action flux known as the Manley-Rowe relations. This reduces the dynamics of FWM to the one-dimensional intersection between the closed two-dimensional surface and the phase-plane given by the conserved Hamiltonian. The analysis is advantageous for visualizing phase...

  19. Highly efficient non-degenerate four-wave mixing under dual-mode injection in InP/InAs quantum-dash and quantum-dot lasers at 1.55 μm

    Science.gov (United States)

    Sadeev, T.; Huang, H.; Arsenijević, D.; Schires, K.; Grillot, F.; Bimberg, D.

    2015-11-01

    This work reports on non-degenerate four-wave mixing under dual-mode injection in metalorganic vapor phase epitaxy grown InP/InAs quantum-dash and quantum dot Fabry-Perot laser operating at 1550 nm. High values of normalized conversion efficiency of -18.6 dB, optical signal-to-noise ratio of 37 dB, and third order optical susceptibility normalized to material gain χ(3)/g0 of ˜4 × 10-19 m3/V3 are measured for 1490 μm long quantum-dash lasers. These values are similar to those obtained with distributed-feedback lasers and semiconductor optical amplifiers, which are much more complicated to fabricate. On the other hand, due to the faster gain saturation and enhanced modulation of carrier populations, quantum-dot lasers demonstrate 12 dB lower conversion efficiency and 4 times lower χ(3)/g0 compared to quantum dash lasers.

  20. Highly efficient non-degenerate four-wave mixing under dual-mode injection in InP/InAs quantum-dash and quantum-dot lasers at 1.55 μm

    Energy Technology Data Exchange (ETDEWEB)

    Sadeev, T., E-mail: tagir@mailbox.tu-berlin.de; Arsenijević, D. [Institut für Festkörperphysik, Technische Universität Berlin, Berlin 10623 (Germany); Huang, H.; Schires, K. [Télécom Paristech, Université Paris-Saclay, 46 rue Barrault, CNRS LTCI 75634 Paris Cedex 13 (France); Grillot, F. [Télécom Paristech, Université Paris-Saclay, 46 rue Barrault, CNRS LTCI 75634 Paris Cedex 13 (France); Center for High Technology Materials, University of New-Mexico, Albuquerque, New Mexico 1313 (United States); Bimberg, D. [Institut für Festkörperphysik, Technische Universität Berlin, Berlin 10623 (Germany); King Abdulaziz University, 22254 Jeddah (Saudi Arabia)

    2015-11-09

    This work reports on non-degenerate four-wave mixing under dual-mode injection in metalorganic vapor phase epitaxy grown InP/InAs quantum-dash and quantum dot Fabry-Perot laser operating at 1550 nm. High values of normalized conversion efficiency of −18.6 dB, optical signal-to-noise ratio of 37 dB, and third order optical susceptibility normalized to material gain χ{sup (3)}/g{sub 0} of ∼4 × 10{sup −19} m{sup 3}/V{sup 3} are measured for 1490 μm long quantum-dash lasers. These values are similar to those obtained with distributed-feedback lasers and semiconductor optical amplifiers, which are much more complicated to fabricate. On the other hand, due to the faster gain saturation and enhanced modulation of carrier populations, quantum-dot lasers demonstrate 12 dB lower conversion efficiency and 4 times lower χ{sup (3)}/g{sub 0} compared to quantum dash lasers.

  1. Electrically controllable spontaneous magnetism in nanoscale mixed phase multiferroics.

    Science.gov (United States)

    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

    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 BiFeO₃. 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.

  2. Quantum Image Processing and Storage with Four Wave Mixing

    Science.gov (United States)

    2016-08-10

    Joint Quantum Institute NIST/University of Maryland CSS Building (224), Room 2207 4254 Stadium Drive College Park, MD 20742 Abstract Interest in...interferometer [17] and recently we have performed a number of simulations that have led us to propose different interferometer designs and compare

  3. Mixed lipid bilayers with locally varying spontaneous curvature and bending.

    Science.gov (United States)

    Gueguen, Guillaume; Destainville, Nicolas; Manghi, Manoel

    2014-08-01

    A model of lipid bilayers made of a mixture of two lipids with different average compositions on both leaflets, is developed. A Landau Hamiltonian describing the lipid-lipid interactions on each leaflet, with two lipidic fields ψ 1 and ψ 2, is coupled to a Helfrich one, accounting for the membrane elasticity, via both a local spontaneous curvature, which varies as C 0 + C 1(ψ 1 - ψ 2/2), and a bending modulus equal to κ 0 + κ 1(ψ 1 + ψ 2)/2. This model allows us to define curved patches as membrane domains where the asymmetry in composition, ψ 1 - ψ 2, is large, and thick and stiff patches where ψ 1 + ψ 2 is large. These thick patches are good candidates for being lipidic rafts, as observed in cell membranes, which are composed primarily of saturated lipids forming a liquid-ordered domain and are known to be thick and flat nano-domains. The lipid-lipid structure factors and correlation functions are computed for globally spherical membranes and planar ones and for a whole set of parameters including the surface tension and the coupling in the two leaflet compositions. Phase diagrams are established, within a Gaussian approximation, showing the occurrence of two types of Structure Disordered phases, with correlations between either curved or thick patches, and an Ordered phase, corresponding to the divergence of the structure factor at a finite wave vector. The varying bending modulus plays a central role for curved membranes, where the driving force κ 1 C 0 (2) is balanced by the line tension, to form raft domains of size ranging from 10 to 100 nm. For planar membranes, raft domains emerge via the cross-correlation with curved domains. A global picture emerges from curvature-induced mechanisms, described in the literature for planar membranes, to coupled curvature- and bending-induced mechanisms in curved membranes forming a closed vesicle.

  4. Observation of correlated atom pairs in spontaneous four wave mixing of two colliding Bose-Einstein condensates; Observation de paires d'atomes correles au travers de la collision de deux condensats de Bose-Einstein

    Energy Technology Data Exchange (ETDEWEB)

    Perrin, A

    2007-11-15

    In this thesis, we report on the observation of pairs of correlated atoms produced in the collision of two Bose-Einstein condensates of metastable helium. Three laser beams perform a Raman transfer which extracts the condensate from the magnetic trap and separates it into two parts with opposite mean momenta. While the condensates propagate, elastic scattering of pairs of atoms occurs, whose momenta satisfy energy and momentum conservation laws. Metastable helium atoms large internal energy allows the use of a position-sensitive, single-atom detector which permits a three-dimensional reconstruction of the scattered atoms'momenta. The statistics of these momenta show correlations for atoms with opposite momenta. The measured correlation volume can be understood from the uncertainty-limited momentum spread of the colliding condensates. This interpretation is confirmed by the observation of the momentum correlation function for two atoms scattered in the same direction. This latter effect is a manifestation of the Hanbury Brown-Twiss effect for indistinguishable bosons. Such a correlated-atom-pair source is a first step towards experiments in which one would like to confirm the pairs'entanglement. (author)

  5. Efficient algorithms for non-linear four-wave interactions

    NARCIS (Netherlands)

    Van Vledder, G.P.

    2012-01-01

    This paper addresses the on-going activities in the development of efficient methods for computing the non-linear four-wave interactions in operational discrete third-generation wind-wave models. It is generally assumed that these interactions play an important role in the evolution of wind

  6. Impact of Molecular Orientation and Spontaneous Interfacial Mixing on the Performance of Organic Solar Cells

    KAUST Repository

    Ngongang Ndjawa, Guy Olivier

    2015-07-28

    A critically important question that must be answered to understand how organic solar cells operate and should be improved is how the orientation of the donor and acceptor molecules at the interface influences exciton diffusion, exciton dissociation by electron transfer and recombination. It is exceedingly difficult to probe the orientation in bulk heterojunctions because there are many interfaces and they are arranged with varying angles with respect to the substrate. One of the best ways to study the interface is to make bilayer solar cells with just one donor-acceptor interface. Zinc phthalocyanine is particularly interesting to study because its orientation can be adjusted by using a 2-nm-thick copper iodide seed layer before it is deposited. Previous studies have claimed that solar cells in which fullerene acceptor molecules touch the face of zinc phthalocyanine have more current than ones in which the fullerenes touch the edge of zinc phthalocyanine because of suppressed recombination. We have more thoroughly characterized the system using in situ x-ray photoelectron spectroscopy and found that the interfaces are not as sharp as previous studies claimed when formed at room temperature or above. Fullerenes have a much stronger tendency to mix into the face-on films than into the edge-on films. Moreover we show that almost all of the increase in the current with face-on films can be attributed to improved exciton diffusion and to the formation of a spontaneously mixed interface, not suppressed recombination. This work highlights the importance of spontaneous interfacial molecular mixing in organic solar cells, the extent of which depends on molecular orientation of frontier molecules in donor domains.

  7. A new model of central lid margin apposition and tear film mixing in spontaneous blinking.

    Science.gov (United States)

    Pult, Heiko; Korb, Donald R; Murphy, Paul J; Riede-Pult, Britta H; Blackie, Caroline

    2015-06-01

    To investigate tear film spreading and central lid position in spontaneous blinks and to propose a model of the central lid position of the closed eye in such blinks. In vivo: lid margin position and geometry of 15 subjects (9 female; median age=45 years) were evaluated by high-speed video and slit-lamp microscope video in consecutive spontaneous blinks. Upper lid (UL) tear meniscus (TM) depth was observed in the open and almost closed eye. Eyelid geometry, position and UL TM depth were analysed by Image-J Software. Lid margin thicknesses were measured with a Scheimpflug camera. In vitro: tear film spreading and lipid layer formation were simulated on a lubricated glass plate and videoed by high-speed camera (JVC, GZ-GX1BE, Japan). In vivo: the median central lid margin thickness was not significantly (p=0.258) different between UL (1.8mm) and LL (1.7mm) in the opened eye. During blinking, UL remained perpendicular to the corneal surface, while LL tilted in and thinned. A scaled model diagram was created and revealed an over-blink of the UL over the LL (>0.7mm) and a height offset of the posterior lid margin of >0.7mm. In vitro: the LL TM fused with the UL TM even before full lid touch due to capillary bridge building. The central UL overlaps the central LL during spontaneous blinking. This provides the appearance of complete closure. The space that results from the lack of lid margin apposition influences the fusion of the upper and lower TM and ultimately tear film mixing. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  8. Wave-turbulence theory of four-wave nonlinear interactions

    Science.gov (United States)

    Chibbaro, Sergio; Dematteis, Giovanni; Josserand, Christophe; Rondoni, Lamberto

    2017-08-01

    The Sagdeev-Zaslavski (SZ) equation for wave turbulence is analytically derived, both in terms of a generating function and of a multipoint probability density function (PDF), for weakly interacting waves with initial random phases. When the initial amplitudes are also random, a one-point PDF equation is derived. Such analytical calculations remarkably agree with results obtained in totally different fashions. Numerical investigations of the two-dimensional nonlinear Schrödinger equation (NLSE) and of a vibrating plate prove the following: (i) Generic Hamiltonian four-wave systems rapidly attain a random distribution of phases independently of the slower dynamics of the amplitudes, vindicating the hypothesis of initially random phases. (ii) Relaxation of the Fourier amplitudes to the predicted stationary distribution (exponential) happens on a faster time scale than relaxation of the spectrum (Rayleigh-Jeans distribution). (iii) The PDF equation correctly describes dynamics under different forcings: The NLSE has an exponential PDF corresponding to a quasi-Gaussian solution, as the vibrating plates, that also shows some intermittency at very strong forcings.

  9. Mixed cryoglobulinemia-associated Sjögren's syndrome leading to spontaneous rupture of the kidney: a case report

    Directory of Open Access Journals (Sweden)

    Haddiya I

    2016-03-01

    Full Text Available Intissar Haddiya,1 Hakim Hamzaoui,1 Zitouna Alhamany,2 Fatime-zohra Berkchi,1 Hakima Rhou,1 Loubna Benamar,1 Naima Ouzeddoun,1 Rabea Bayahia1 1Department of Nephrology-Dialysis-Renal Transplantation, Ibn Sina University Hospital, Rabat, Morocco; 2Department of Pathology, Rabat Children's Hospital, Ibn Sina University Hospital, Rabat, Morocco Background: Spontaneous rupture of the kidney is uncommon and is mainly caused by renal tumors. Only a few cases are caused by vasculitis. We report here the first case of spontaneous rupture of kidney resulting from mixed cryoglobulinemia. Case presentation: A 44-year-old man presented with sudden onset of fever, acute pulmonary edema, left flank abdominal pain unassociated with trauma, and rapidly progressive renal failure requiring dialysis. Computed tomography of the abdomen revealed a large perirenal hematoma of the left kidney. During conservative surgery, the patient underwent renal biopsy that showed renal vasculitis and membranoproliferative glomerulonephritis with intracapillary microthrombi. Tests were positive for mixed cryoglobulinemia caused by Sjögren's syndrome. The patient was better after immunosuppressive therapy, with the disappearance of clinical symptoms and the recovery of baseline renal function. Conclusion: We report on this case and discuss a possible link between spontaneous rupture of kidney and mixed cryoglobulinemia-associated Sjögren's syndrome. Keywords: mixed cryoglobulinemia, Sjögren's syndrome, spontaneous rupture of kidney, renal hematoma, Wünderlich syndrome

  10. Establishment of primary mixed cell cultures from spontaneous canine mammary tumors: Characterization of classic and new cancer-associated molecules

    Science.gov (United States)

    Gentile, Luciana B.; Nagamine, Marcia K.; Biondi, Luiz R.; Sanches, Daniel S.; Toyota, Fábio; Giovani, Tatiane M.; de Jesus, Isis P.; da Fonseca, Ivone I. M.; Queiroz-Hazarbassanov, Nicolle; Diaz, Bruno L.; Salles Gomes, Cristina de O. Massoco

    2017-01-01

    There are many factors which make canine cancer like cancer in humans. The occurrence of spontaneous mammary tumors in pet dogs, tumor genetics, molecular targets and exposure to the same environmental risk factors are among these factors. Therefore, the study of canine cancer can provide useful information to the oncology field. This study aimed to establish and characterize a panel of primary mixed cell cultures obtained from spontaneous canine mammary tumors. Eight established cell cultures obtained from one normal mammary gland, one complex adenoma, one mixed adenoma, two complex carcinomas and two mixed carcinomas were analyzed. The gene expression levels of classic molecular cancer players such as fibroblast growth factor receptor (FGFR) 2, breast cancer (BRCA) 1, BRCA2 and estrogen receptor (ESR) 1 were evaluated. For the first time, three orphan nuclear receptors, estrogen-related receptors (ERRs) α, β and γ were studied in canine mammary cancer. The highest expression level of ERRα was observed in complex carcinoma-derived cell culture, while the highest levels of ERRβ and γ were observed in cells derived from a mixed carcinoma. Meanwhile, complex carcinomas presented the highest levels of expression of ESR1, BRCA1 and FGFR2 among all samples. BRCA2 was found exclusively in complex adenoma. The transcription factor GATA3 had its highest levels in mixed carcinoma samples and its lowest levels in complex adenoma. Proliferation assays were also performed to evaluate the mixed cell cultures response to ER ligands, genistein and DES, both in normoxia and hypoxic conditions. Our results demonstrate that morphological and functional studies of primary mixed cell cultures derived from spontaneous canine mammary tumors are possible and provide valuable tool for the study of various stages of mammary cancer development. PMID:28945747

  11. Short-time fourth-order squeezing effects in spontaneous and stimulated four- and six-wave mixing processes

    CERN Document Server

    Giri, D K

    2003-01-01

    The concept of fourth-order squeezing of the electromagnetic field is investigated in the fundamental mode in spontaneous and stimulated four- and six-wave mixing processes under the short-time approximation based on a fully quantum mechanical approach. The coupled Heisenberg equations of motion involving real and imaginary parts of the quadrature operators are established. The possibility of obtaining fourth-order squeezing is studied. The dependence of fourth-order squeezing on the number of photons is also investigated. It is shown that fourth-order squeezing, which is a higher-order squeezing, allows a much larger fractional noise reduction than lower-order squeezing. It is shown that squeezing is greater in a stimulated process than the corresponding squeezing in spontaneous interaction. The conditions for obtaining maximum and minimum squeezing are obtained. We have also established the non-classical nature of squeezed radiation using the Glauber-Sudarshan representation.

  12. Numerical model of frequency converter based on four-wave mixing in semiconductor amplifiers

    DEFF Research Database (Denmark)

    Cassioli, D.; Scotti, S.; Mecozzi, A.

    1999-01-01

    We describe a numerical model of the dynamics of a semiconductor optical amplifier that includes the description of the nonlinear optical processes within the waveguide and the longitudinal inhomogeneity caused by the saturating field.......We describe a numerical model of the dynamics of a semiconductor optical amplifier that includes the description of the nonlinear optical processes within the waveguide and the longitudinal inhomogeneity caused by the saturating field....

  13. Bidirectional Four-Wave Mixing in Semiconductor Optical Amplifiers: Theory and Experiment

    DEFF Research Database (Denmark)

    Bischoff, Svend; Buxens, Alvaro A.; Poulsen, Henrik Nørskov

    1999-01-01

    ) is theoretically predicted for bit rates of 10, 20 and 40 Gb/s and is shown to be in agreement with measurements performed at 10 and 20 Gb/s. Measurements of the clear/drop functionality using the bidirectional technique show excellent performance for a 4 x 10 Gb/s signal and is again in good agreement...

  14. Effects of nonlinear phase modulation on quantum frequency conversion using four-wave mixing Bragg scattering

    DEFF Research Database (Denmark)

    Andersen, Lasse Mejling; McKinstrie, C. J.; Rottwitt, Karsten

    2013-01-01

    Recently, we solved the coupled-mode equations for Bragg scattering (BS) in the low- and high-conversion regimes, but without the effects of nonlinear phase modulation (NPM). We now present solutions and Green functions in the low-conversion regime that include NPM. We find that NPM does not change...

  15. Flexible DWDM Grid Manipulation Using Four Wave Mixing-based Time Lenses

    DEFF Research Database (Denmark)

    Røge, Kasper Meldgaard; Guan, Pengyu; Mulvad, Hans Christian Hansen

    2014-01-01

    An experimental demonstration of dense wavelength-division multiplexing (DWDM) grid manipulation is carried out using two time lenses. A DWDM spectrum is compressed from a 100-GHz to a 28-GHz grid with error-free performance.......An experimental demonstration of dense wavelength-division multiplexing (DWDM) grid manipulation is carried out using two time lenses. A DWDM spectrum is compressed from a 100-GHz to a 28-GHz grid with error-free performance....

  16. Silicon-on-Sapphire Waveguides: Mode-converting Couplers and Four-wave Mixing

    Science.gov (United States)

    2014-09-01

    and Engineering (NISE) Program at SSC Pacific funded this Basic Research project. This is a work of the United States Government and...masking step. Then they were coated with a 390-nm UV210 photoresist. The wafers were exposed in a Canon® FPA-3000 EX5 stepper at 280 J/m2. Using this... stepper at 180 J/m2. We also used PECVD to deposit SiN. The PECVD nitride deposited is not very stoichiometric (0.8 to 1.0:1 vs. 0.75:1 for thermal

  17. Transient Gratings, Four-Wave Mixing and Polariton Effects in Nonlinear Optics

    NARCIS (Netherlands)

    Knoester, Jasper; Mukamel, Shaul

    1991-01-01

    Nonlinear optical susceptibilities provide a convenient means of relating macroscopic optical measurements to microscopic models. The susceptibilities are most useful when the radiation field and the material degrees of freedom are weakly coupled. In the opposite case, the dynamics is interpreted in

  18. Investigation of soot by two-color four-wave mixing

    Energy Technology Data Exchange (ETDEWEB)

    Hemmerling, B.; Stampanoni-Panariello, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    A novel, non-intrusive technique has been used for the temporally resolved investigation of the interaction of laser radiation and soot in a flame. While there is a fairly good agreement between measurement and simulation remaining discrepancies indicate some shortcomings of the model employed. (author) 2 figs., 2 refs.

  19. Diffractive optics based four-wave, six-wave, ..., nu-wave nonlinear spectroscopy.

    Science.gov (United States)

    Miller, R J Dwayne; Paarmann, Alexander; Prokhorenko, Valentyn I

    2009-09-15

    A detailed understanding of chemical processes requires information about both structure and dynamics. By definition, a reaction involves nonstationary states and is a dynamic process. Structure describes the atomic positions at global minima in the nuclear potential energy surface. Dynamics are related to the anharmonicities in this potential that couple different minima and lead to changes in atomic positions (reactions) and correlations. Studies of molecular dynamics can be configured to directly access information on the anharmonic interactions that lead to chemical reactions and are as central to chemistry as structural information. In this regard, nonlinear spectroscopies have distinct advantages over more conventional linear spectroscopies. Because of this potential, nonlinear spectroscopies could eventually attain a comparable level of importance for studying dynamics on the relevant time scales to barrier crossings and reactive processes as NMR has for determining structure. Despite this potential, nonlinear spectroscopy has not attained the same degree of utility as linear spectroscopy largely because nonlinear studies are more technically challenging. For example, unlike the linear spectrometers that exist in almost all chemistry departments, there are no "black box" four-wave mixing spectrometers. This Account describes recent advances in the application of diffractive optics (DOs) to nonlinear spectroscopy, which reduces the complexity level of this technology to be closer to that of linear spectroscopy. The combination of recent advances in femtosecond laser technology and this single optic approach could bring this form of spectroscopy out of the exclusive realm of specialists and into the general user community. However, the real driving force for this research is the pursuit of higher sensitivity limits, which would enable new forms of nonlinear spectroscopy. This Account chronicles the research that has now extended nonlinear spectroscopy to six

  20. Relationship between mixed venous oxygen saturation and regional cerebral oxygenation in awake, spontaneously breathing cardiac surgery patients.

    Science.gov (United States)

    Schön, J; Heringlake, M; Berger, K-U; Volker Groesdonk, H; Sedemund-Adib, B; Paarmann, H

    2011-10-01

    In search of a non-invasive method for estimation of the oxygen balance this prospective study evaluates the relationship between regional cerebral oxygenation (rScO2) and mixed venous oxygen saturation in awake, spontaneously breathing patients after cardiac surgery. After approval by the local ethical committee and written informed consent, 26 consecutive patients after cardiac surgery with cardiopulmonary bypass were enrolled. On intensive care unit (ICU), several hours after extubation, patients were connected to the INVOS 5100 cerebral monitor. Blood samples for determination of mixed venous oxygen saturation (SvO2) and central venous oxygen saturation (ScvO2) were drawn successively and rScO2 was documented. Patients were studied twice, breathing room air for the first measurement cycle, and breathing 4L/min supplemental oxygen by face mask, achieving a transcutaneous oxygen saturation above 98%, for a second measurement. Hemodynamic variables, hemoglobin and arterial carbon dioxide tension (PaCO2) remained stable between the two measurement cycles. Without oxygen, SvO2 and rScO2 showed a bias of -2.0%, limits of agreement (LOA) of -15.0 to 10.9% and a percentage error (PE) of 20.3%. SvO2 and ScvO2 showed a bias of -3.9%, LOA of -13.9 to 6.2% and PE 15.7%. With oxygen, the bias between SvO2 and rScO2 was -2.5%, LOA -14.2 to 9.2%, PE 17.2%. Between SvO2 and ScvO2 the bias was -4.1%, LOA -10.2 to 2.1%, PE 9.0%. The rScO2 measured by near infrared spectroscopy was sufficiently representing mixed venous oxygen saturation in awake, hemodynamically stable, spontaneously breathing patients after cardiac surgery. The agreement was comparable to the agreement between SvO2 and ScvO2 with smaller differences in the lower ranges of SvO2.

  1. Spontaneous Time Symmetry Breaking in System with Mixed Strategy Nash Equilibrium: Evidences in Experimental Economics Data

    Science.gov (United States)

    Wang, Zhijian; Xu, Bin; Zhejiang Collaboration

    2011-03-01

    In social science, laboratory experiment with human subjects' interaction is a standard test-bed for studying social processes in micro level. Usually, as in physics, the processes near equilibrium are suggested as stochastic processes with time-reversal symmetry (TRS). To the best of our knowledge, near equilibrium, the breaking time symmetry, as well as the existence of robust time anti-symmetry processes, has not been reported clearly in experimental economics till now. By employing Markov transition method to analysis the data from human subject 2x2 Games with wide parameters and mixed Nash equilibrium, we study the time symmetry of the social interaction process near Nash equilibrium. We find that, the time symmetry is broken, and there exists a robust time anti-symmetry processes. We also report the weight of the time anti-symmetry processes in the total processes of each the games. Evidences in laboratory marketing experiments, at the same time, are provided as one-dimension cases. In these cases, time anti-symmetry cycles can also be captured. The proposition of time anti-symmetry processes is small, but the cycles are distinguishable.

  2. Spontaneous adsorption of coiled-coil model peptides K and E to a mixed lipid bilayer.

    Science.gov (United States)

    Pluhackova, Kristyna; Wassenaar, Tsjerk A; Kirsch, Sonja; Böckmann, Rainer A

    2015-03-26

    A molecular description of the lipid-protein interactions underlying the adsorption of proteins to membranes is crucial for understanding, for example, the specificity of adsorption or the binding strength of a protein to a bilayer, or for characterizing protein-induced changes of membrane properties. In this paper, we extend an automated in silico assay (DAFT) for binding studies and apply it to characterize the adsorption of the model fusion peptides E and K to a mixed phospholipid/cholesterol membrane using coarse-grained molecular dynamics simulations. In addition, we couple the coarse-grained protocol to reverse transformation to atomistic resolution, thereby allowing to study molecular interactions with high detail. The experimentally observed differential binding of the peptides E and K to membranes, as well as the increased binding affinity of helical over unstructered peptides, could be well reproduced using the polarizable Martini coarse-grained (CG) force field. Binding to neutral membranes is shown to be dominated by initial binding of the positively charged N-terminus to the phospholipid headgroup region, followed by membrane surface-aligned insertion of the peptide at the interface between the hydrophobic core of the membrane and its polar headgroup region. Both coarse-grained and atomistic simulations confirm a before hypothesized snorkeling of lysine side chains for the membrane-bound state of the peptide K. Cholesterol was found to be enriched in peptide vicinity, which is probably of importance for the mechanism of membrane fusion. The applied sequential multiscale method, using coarse-grained simulations for the slow adsorption process of peptides to membranes followed by backward transformation to atomistic detail and subsequent atomistic simulations of the preformed peptide-lipid complexes, is shown to be a versatile approach to study the interactions of peptides or proteins with biomembranes.

  3. Adverse events associated with incretin-based drugs in Japanese spontaneous reports: a mixed effects logistic regression model

    Directory of Open Access Journals (Sweden)

    Daichi Narushima

    2016-03-01

    Full Text Available Background: Spontaneous Reporting Systems (SRSs are passive systems composed of reports of suspected Adverse Drug Events (ADEs, and are used for Pharmacovigilance (PhV, namely, drug safety surveillance. Exploration of analytical methodologies to enhance SRS-based discovery will contribute to more effective PhV. In this study, we proposed a statistical modeling approach for SRS data to address heterogeneity by a reporting time point. Furthermore, we applied this approach to analyze ADEs of incretin-based drugs such as DPP-4 inhibitors and GLP-1 receptor agonists, which are widely used to treat type 2 diabetes. Methods: SRS data were obtained from the Japanese Adverse Drug Event Report (JADER database. Reported adverse events were classified according to the MedDRA High Level Terms (HLTs. A mixed effects logistic regression model was used to analyze the occurrence of each HLT. The model treated DPP-4 inhibitors, GLP-1 receptor agonists, hypoglycemic drugs, concomitant suspected drugs, age, and sex as fixed effects, while the quarterly period of reporting was treated as a random effect. Before application of the model, Fisher’s exact tests were performed for all drug-HLT combinations. Mixed effects logistic regressions were performed for the HLTs that were found to be associated with incretin-based drugs. Statistical significance was determined by a two-sided p-value <0.01 or a 99% two-sided confidence interval. Finally, the models with and without the random effect were compared based on Akaike’s Information Criteria (AIC, in which a model with a smaller AIC was considered satisfactory. Results: The analysis included 187,181 cases reported from January 2010 to March 2015. It showed that 33 HLTs, including pancreatic, gastrointestinal, and cholecystic events, were significantly associated with DPP-4 inhibitors or GLP-1 receptor agonists. In the AIC comparison, half of the HLTs reported with incretin-based drugs favored the random effect

  4. [Spontaneous transformation in mixed cultures of various types of Acinetobacter and during joint growth of Acinetobacter calcoaceticus with Escherichia coli and Pseudomonas aeruginosa].

    Science.gov (United States)

    Mindlin, S Z; Gorlenko, Zh M; Bass, I A; Khachikian, N A

    1990-10-01

    The transfer of chromosomal and plasmid genes was studied via spontaneous transformation is mixed cultures of Acinetobacter spp. It turned out that any Acinetobacter strain, irrespective of its species specificity, serves as chromosomal DNA donor in case the mixed culture contains competent cells of the recipient strain. No transfer took place when non-related bacteria were used as donors. We also studied the transfer into Ac. calcoaceticus competent strain cells of small non-conjugative plasmids having broad host range (RSF1010, pAK1). In these cases, DNA donors could be not only acinetobacters of other species, but bacteria belonging to other systematic groups (families)--E. coli and P. aeruginosa. The transfer of plasmids from cells of unrelated bacteria took place with a frequency of about 10(-5)-10(-6). The possible role of spontaneous transformation in horizontal gene transfer is discussed.

  5. Self-Organization in Active Cytoskeletal Mixtures: Cilia-like Beating of Microtubule Bundles and Spontaneous Bulk Mixing

    Science.gov (United States)

    Sanchez, Tim

    This thesis discusses circularization and supercoiling of actin biofilaments, as well as the various examples of self-organization observed in a simple non-equilibrium system of microtubules, motor clusters, and a depletion agent (PEG). When the ends of an actin filament approach each other, annealing can occur, resulting in the assumption of a circular conformation. In order to facilitate this experimentally, we dramatically reduce the space available for the ends to explore by confining the filaments to a quasi-2D region. This is accomplished through the use of a depletion attraction. In addition to the pronounced effects of this topological ring constraint on the statistical fluctuations of the filaments, we also observe a spontaneous supercoiling transition in fluorescently labeled actin rings that is directly driven by illumination. To better understand this transition in natural twist, we investigate real-time twist of a filament trapped between two beads, held by optical traps. The main focus of this graduate work was on the behavior of non-equilibrium in vitro mixtures of microtubules, kinesin motor clusters, and a depletion agent. We observed several striking and distinct examples of self-organization on near-macroscopic length scales, due to the interactions of very simple components. First we investigate the driving mechanism behind the beating of biological cilia and flagella, and find that this beating functionality can be reproduced in our vastly simpler system. This occurs only when minimalist components are reconstituted: motors, biofilaments, elastic links to hold the filaments together, and a basal attachment. Beyond the cooperativity of the motors to produce oscillatory beating in individual bundles, we also observe that active bundles in close proximity can synchronize their beating to produce stable, periodic metachronal waves that propagate along the bundle array. By changing only the length distribution of the microtubules in our system, we

  6. Four-Wave Optical Parametric Amplification in a Raman-Active Gas

    Directory of Open Access Journals (Sweden)

    Yuichiro Kida

    2015-08-01

    Full Text Available Four-wave optical parametric amplification (FWOPA in a Raman-active medium is experimentally investigated by use of an air-filled hollow fiber. A femtosecond pump pulse shorter than the period of molecular motion excites the coherent molecular motion of the Raman-active molecules during the parametric amplification of a signal pulse. The excited coherent motion modulates the frequency of the signal pulse during the parametric amplification, and shifts it to lower frequencies. The magnitude of the frequency redshift depends on the pump intensity, resulting in intensity-dependent spectral characteristics that are different from those in the FWOPA induced in a noble-gas-filled hollow fiber.

  7. SU(3) gauge family symmetry and prediction for the lepton-flavor mixing and neutrino masses with maximal spontaneous CP violation

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yueliang, E-mail: ylwu@itp.ac.cn [State Key Laboratory of Theoretical Physics (SKLTP), Kavli Institute for Theoretical Physics China (KITPC), Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2012-08-14

    A model for the lepton-flavor mixing and CP violation is proposed based on the SU{sub F}(3) gauge family symmetry and the Majorana feature of neutrinos. A consistent prediction for the lepton-flavor mixing and masses is shown to be resulted from the appropriate vacuum structure of SU{sub F}(3) gauge symmetry breaking. By choosing the SU{sub F}(3) gauge fixing condition to possess a residual Z{sub 2} symmetry and requiring the vacuum structure of spontaneous symmetry breaking to have approximate global U(1) family symmetries, we obtain naturally the tri-bimaximal mixing matrix and largely degenerate neutrino masses in the neutrino sector and the small mixing matrix in the charged-lepton sector. With a simple ansatz that all the smallness due to the approximate global U(1) family symmetries is characterized by a single Wolfenstein parameter {lambda} Asymptotically-Equal-To 0.22, and the charged-lepton mixing matrix has a similar hierarchy structure as the CKM quark mixing matrix, we arrive at a consistent prediction for the MNSP lepton-flavor mixing with a maximal spontaneous CP violation: {delta}={pi}/2, sin{sup 2}{theta}{sub 13} Asymptotically-Equal-To 1/2 {lambda}{sup 2} Asymptotically-Equal-To 0.024 (sin{sup 2}2{theta}{sub 13} Asymptotically-Equal-To 0.094), sin{sup 2}{theta}{sub 12} Asymptotically-Equal-To 1/3 (1-2{lambda}{sup 3}) Asymptotically-Equal-To 0.326 and sin{sup 2}{theta}{sub 23} Asymptotically-Equal-To 1/2 (1-{lambda}{sup 2}) Asymptotically-Equal-To 0.48, which agree well with the current experimental data. The CP-violating Jarlskog-invariant is obtained to be J{sub CP} Asymptotically-Equal-To 1/6 {lambda}(1-{lambda}{sup 2}/2-{lambda}{sup 3})sin{delta} Asymptotically-Equal-To 0.035, which is detectable in next generation neutrino experiment. The small masses of the neutrinos and charged leptons are simply attributed to the standard seesaw mechanism. The largely degenerate neutrino masses with the normal hierarchy and inverse hierarchy are discussed

  8. Three-wave and four-wave interactions in gravity wave turbulence

    Science.gov (United States)

    Aubourg, Quentin; Campagne, Antoine; Peureux, Charles; Ardhuin, Fabrice; Sommeria, Joel; Viboud, Samuel; Mordant, Nicolas

    2017-11-01

    Weak-turbulence theory is a statistical framework to describe a large ensemble of nonlinearly interacting waves. The archetypal example of such system is the ocean surface that is made of interacting surface gravity waves. Here we describe a laboratory experiment dedicated to probe the statistical properties of turbulent gravity waves. We set up an isotropic state of interacting gravity waves in the Coriolis facility (13-m-diam circular wave tank) by exciting waves at 1 Hz by wedge wave makers. We implement a stereoscopic technique to obtain a measurement of the surface elevation that is resolved in both space and time. Fourier analysis shows that the laboratory spectra are systematically steeper than the theoretical predictions and the field observations in the Black Sea by Leckler et al. [F. Leckler et al., J. Phys. Oceanogr. 45, 2484 (2015), 10.1175/JPO-D-14-0237.1]. We identify a strong impact of surface dissipation on the scaling of the Fourier spectrum at the scales that are accessible in the experiments. We use bicoherence and tricoherence statistical tools in frequency and/or wave-vector space to identify the active nonlinear coupling. These analyses are also performed on the field data by Leckler et al. for comparison with the laboratory data. Three-wave coupling is characterized by and shown to involve mostly quasiresonances of waves with second- or higher-order harmonics. Four-wave coupling is not observed in the laboratory but is evidenced in the field data. We discuss temporal scale separation to explain our observations.

  9. Experimental investigation of gravity wave turbulence and of non-linear four wave interactions..

    Science.gov (United States)

    Berhanu, Michael

    2017-04-01

    Using the large basins of the Ecole Centrale de Nantes (France), non-linear interactions of gravity surface waves are experimentally investigated. In a first part we study statistical properties of a random wave field regarding the insights from the Wave Turbulence Theory. In particular freely decaying gravity wave turbulence is generated in a closed basin. No self-similar decay of the spectrum is observed, whereas its Fourier modes decay first as a time power law due to nonl-inear mechanisms, and then exponentially due to linear viscous damping. We estimate the linear, non-linear and dissipative time scales to test the time scale separation. By estimation of the mean energy flux from the initial decay of wave energy, the Kolmogorov-Zakharov constant of the weak turbulence theory is evaluated. In a second part, resonant interactions of oblique surface gravity waves in a large basin are studied. We generate two oblique waves crossing at an acute angle. These mother waves mutually interact and give birth to a resonant wave whose properties (growth rate, resonant response curve and phase locking) are fully characterized. All our experimental results are found in good quantitative agreement with four-wave interaction theory. L. Deike, B. Miquel, P. Gutiérrez, T. Jamin, B. Semin, M. Berhanu, E. Falcon and F. Bonnefoy, Role of the basin boundary conditions in gravity wave turbulence, Journal of Fluid Mechanics 781, 196 (2015) F. Bonnefoy, F. Haudin, G. Michel, B. Semin, T. Humbert, S. Aumaître, M. Berhanu and E. Falcon, Observation of resonant interactions among surface gravity waves, Journal of Fluid Mechanics (Rapids) 805, R3 (2016)

  10. Longitudinal interplay between posttraumatic stress symptoms and coping self-efficacy : A four-wave prospective study

    NARCIS (Netherlands)

    Bosmans, M.W.G.; van der Velden, P.G.

    2015-01-01

    Trauma-related coping self-efficacy (CSE), the perceived capability to manage one's personal functioning and the myriad environmental demands of the aftermath of potentially traumatic events (PTE), has been shown to affect psychological outcomes after these events. Aim of the present four-wave study

  11. Quantum frequency conversion and strong coupling of photonic modes using four-wave mixing in integrated microresonators

    CERN Document Server

    Vernon, Z; Sipe, J E

    2016-01-01

    Single photon-level quantum frequency conversion has recently been demonstrated using silicon nitride microring resonators. The resonance enhancement offered by such systems enables high-efficiency translation of quantum states of light across wide frequency ranges at sub-watt pump powers. Using a quantum-mechanical Hamiltonian formalism, we present a detailed theoretical analysis of the conversion dynamics in these systems, and show that they are capable of converting single- and multi-photon quantum states. Analytic formulas for the conversion efficiency, spectral conversion probability density, and pump power requirements are derived which are in good agreement with previous theoretical and experimental results. We show that with only modest improvement to the state of the art, efficiencies exceeding 95% are achievable using less than 100 mW of pump power. At the critical driving strength that yields maximum conversion efficiency, the spectral conversion probability density is shown to exhibit a flat-toppe...

  12. Design of photonic crystal fibers with highly nonlinear glasses for four-wave-mixing based telecom applications.

    Science.gov (United States)

    Kanka, Jiri

    2008-12-08

    A fully-vectorial mode solver based on the finite element method is employed in a combination with the downhill simplex method the dispersion optimization of photonic crystal fibers made from highly nonlinear glasses. The nonlinear fibers are designed for telecom applications such as parametric amplification, wavelength conversion, ultra-fast switching and regeneration of optical signals. The optimization is carried in terms of the zero dispersion wavelength, dispersion magnitude and nonlinear coefficient and confinement loss in the wavelength range around 1.55 microm. We restrict our work to the index-guiding fiber structures a small number of hexagonally arrayed air holes.

  13. Applications and Optimization of Optical Time Lenses based on Four-Wave Mixing in Highly Nonlinear Fibre

    DEFF Research Database (Denmark)

    Lillieholm, Mads

    2017-01-01

    as a method to implement time lenses, for its ability to impart a parabolic phase profile with high fidelity, and to transparently process and preserve arbitrary amplitude and phase information at ultrahigh data rates. Many time lens demonstrations have been based on FWM with linearly chirped pump pulses...... of dispersion fluctuations on the FWM performance, with the aim of enabling broadband and efficient time lens operation. The fibre is demonstrated for time lens processing of all 32 channels in a 1.6 THz input WDM superchannel with uniform efficiency. The last part of the thesis begins with a detailed numerical...... DF-HNLF are used for the first demonstration of time lenses for advanced optical modulation formats. In this demonstration we perform 4×spectral magnification for quadrature amplitude modulation (QAM) signals up to16-QAM, with >18 nm operational bandwidth observed. The bit-error rate measurements...

  14. Orthogonal Phase Quadratures Conversion to Different Wavelengths Through Phase-Sensitive Four Wave Mixing in an Highly Nonlinear Fiber

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Marco Calabrese, Pachito; Kang, Ning

    2013-01-01

    Phase-sensitive processes exploiting FWM in an HNLF allow simultaneously converting two orthogonal quadratures of an optical signal to different wavelengths. Conversion efficiencies to two 90°-phase-shifted idlers exceeding 10dB of phase-sensitive extinction ratio are obtained experimentally....

  15. A 21-35 kDa Mixed Protein Component from Helicobacter pylori Activates Mast Cells Effectively in Chronic Spontaneous Urticaria.

    Science.gov (United States)

    Tan, Ran-Jing; Sun, He-Qiang; Zhang, Wei; Yuan, Han-Mei; Li, Bin; Yan, Hong-Tao; Lan, Chun-Hui; Yang, Jun; Zhao, Zhuo; Wu, Jin-Jin; Wu, Chao

    2016-12-01

    Helicobacter pylori (H. pylori) seem to involve in the etiology of chronic spontaneous urticaria (CSU). But studies of the pathogenic mechanism are very little. In this study, we detected the serum-specific anti-H. pylori IgG and IgE antibodies in 211 CSU and 137 normal subjects by enzyme-linked immunosorbent assay (ELISA), evaluated the direct activation effects of H. pylori preparations and its protein components on human LAD2 mast cell line in vitro, and analyzed the specific protein ingredients and functions of the most effective H. pylori mixed protein component using liquid chromatography-mass spectrometry and ELISA assay. In CSU patients, the positive rate of anti-H. pylori IgG positive rate was significantly higher than that in normal controls, and the anti-H. pylori IgE levels had no statistical difference between H. pylori-infected patients with and without CSU. Further studies suggested that H. pylori preparations can directly activate human LAD2 mast cell line in a dose-dependent manner and its most powerful protein component was a mixture of 21-35 kDa proteins. Moreover, the 21-35 kDa mixed protein component mainly contained 23 kinds of proteins, which can stimulate the release of histamine, TNF-a, IL-3, IFN-γ, and LTB4 by LAD2 cells in a dose-dependent or time-dependent manner. A 21-35 kDa mixed protein component should be regarded as the most promising pathogenic factor contributing to the CSU associated with H. pylori infection. © 2016 John Wiley & Sons Ltd.

  16. Mixed

    Directory of Open Access Journals (Sweden)

    Pau Baya

    2011-05-01

    Full Text Available Remenat (Catalan (Mixed, "revoltillo" (Scrambled in Spanish, is a dish which, in Catalunya, consists of a beaten egg cooked with vegetables or other ingredients, normally prawns or asparagus. It is delicious. Scrambled refers to the action of mixing the beaten egg with other ingredients in a pan, normally using a wooden spoon Thought is frequently an amalgam of past ideas put through a spinner and rhythmically shaken around like a cocktail until a uniform and dense paste is made. This malleable product, rather like a cake mixture can be deformed pulling it out, rolling it around, adapting its shape to the commands of one’s hands or the tool which is being used on it. In the piece Mixed, the contortion of the wood seeks to reproduce the plasticity of this slow heavy movement. Each piece lays itself on the next piece consecutively like a tongue of incandescent lava slowly advancing but with unstoppable inertia.

  17. Forage yield and nutritive value of Elephant grass, Italian ryegrass and spontaneous growing species mixed with forage peanut or red clover

    Directory of Open Access Journals (Sweden)

    Michelle Schalemberg Diehl

    2014-10-01

    Full Text Available The objective of this research was to evaluate of three grazing systems (GS with elephant grass (EG, Italian ryegrass (IR + spontaneous growing species (SGS; EG + IR + SGS + forage peanut (FP; and EG + IR + SGS + red clover (RC, during the winter and summer periods in rotational grazing with dairy cattle. Experimental design was completely randomized with three treatments, two replicates with repeated measures. Lactating Holstein cows receiving 1% BW-daily feed supplement with concentrate were used in the evaluation. Eight grazing cycles were performed during the experimental period. The values of pre forage mass and stocking rate were 2.52, 2.60 and 2.99 t ha-1 and 2.64, 2.77 and 3.14 animal unit ha-1, respectively for GS. Samples of forage were collected by hand-plucking technique to analyze the crude protein (CP, neutral detergent fiber (NDF, in situ dry matter digestibility (ISDMD, in situ organic matter digestibility (ISOMD of forage present between rows of elephant grass, in the rows of elephant grass and the legumes. Higher value of CP, ISOMD and lower of NDF were observed for the grazing systems mixed with legumes forage.

  18. Wave-mixing solitons in bulk photorefractive crystals

    Science.gov (United States)

    Bugaychuk, S. A.; Kovács, Laszlo; Mandula, Gabor; Polgár, Katalin; Rupp, Romano A.

    2003-12-01

    Instead of unstable solutions for conventional four-wave mixing equation set, we obtain the stationary soliton solution for the dynamic grating amplitude and stable auto-oscillations of the dynamic grating. The dynamics of grating recording is described by the sine-Gordon equations in transmission four-wave mixing with non-local grating. The method to calculate the grating amplitude profile and the both steady state and oscillation regimes is developed.

  19. Rapid Palatal Expansion in the absence of posterior cross-bite to intercept maxillary incisor crowding in the mixed dentition: a CBCT evaluation of spontaneous changes of untouched permanent molars.

    Science.gov (United States)

    Rosa, M; Lucchi, P; Manti, G; Caprioglio, A

    2016-12-01

    The aim of this study was to investigate the reaction of untouched permanent molars following RPE, anchored on deciduous teeth in the early mixed dentition, aimed to solve maxillary anterior crowding in the absence of posterior cross-bite. A prospective clinical trial comprised 35 consecutive patients (20 males and 15 females) treated by the same orthodontist (MR). All patients showed crowding of the upper permanent incisors in the early mixed dentition in the absence of posterior cross-bite. RPE was anchored on second deciduous molars and on the deciduous canines. CBCT was taken before and after the removal of the RPE appliance. The transverse linear changes in width and the variation in the torque of the permanent molars were measured in the coronal plane. Relief of incisor crowding was found in all patients. The transverse width between permanent molars increased significantly. The apices of the upper permanent molars spontaneously expanded more than the crowns, while the opposite happened on the lower permanent molars. Moreover, the untouched upper permanent molars spontaneously uprighted palatally, while the lower permanent molars spontaneously uprighted buccally. The variation in the torque of the permanent molars mirrored transverse normal growth. In the early mixed dentition and in the absence of posterior cross-bite, it is possible to expand transversally the palate while uprighting the upper permanent molars in the opposite direction. RPE anchored on the deciduous teeth in the early mixed dentition, in the absence of posterior cross-bite, provides an "anticipation of transverse growth" and could be indicated to expand the anterior portion of the maxillary arch perimeter to solve upper incisor crowding.

  20. Spontaneous deregulation

    NARCIS (Netherlands)

    Edelman, Benjamin; Geradin, Damien

    Platform businesses such as Airbnb and Uber have risen to success partly by sidestepping laws and regulations that encumber their traditional competitors. Such rule flouting is what the authors call “spontaneous private deregulation,” and it’s happening in a growing number of industries. The authors

  1. Exploiting the spontaneous potential of the electrodes used in the capacitive mixing technique for the extraction of energy from salinity difference

    NARCIS (Netherlands)

    Brogioli, D.; Ziano, R.; Rica, R.A.; Salerno, D.; Kozynchenko, O.; Hamelers, H.V.M.; Mantegazza, F.

    2012-01-01

    The "capacitive mixing" (CAPMIX) technique is aimed at the extraction of energy from the salinity difference between the sea and rivers. It is based on the voltage rise that takes place at the electrodes when changing the salt concentration of the solution in which the two electrodes are dipped. In

  2. Amplitude Equalization of 40 Gb/s RZ-DPSK Signals using Saturation of Four-Wave Mixing in a Highly Nonlinear Fiber

    DEFF Research Database (Denmark)

    Geng, Yan; Peucheret, Christophe; Jeppesen, Palle

    2006-01-01

    We report the first experimental demonstration of amplitude equalization of 40 Gb/s RZ-DPSK signals using saturation of FWM in a HNLF. We show effective power penalty reduction after wavelength conversion of an amplitude distorted signal......We report the first experimental demonstration of amplitude equalization of 40 Gb/s RZ-DPSK signals using saturation of FWM in a HNLF. We show effective power penalty reduction after wavelength conversion of an amplitude distorted signal...

  3. Entanglement and four-wave mixing effects in the dissipation-free nonlinear interaction of two photons at a single atom

    OpenAIRE

    Hofmann, Holger Friedrich; Kojima, Kunihiro; Takeuchi, Shigeki; Sasaki, Keiji

    2003-01-01

    We investigate the nonlinear interaction between two photons in a single-input pulse at an atomic two-level nonlinearity. A one-dimensional model for the propagation of light to and from the atom is used to describe the precise spatiotemporal coherence of the two-photon state. It is shown that the interaction generates spatiotemporal entanglement in the output state similar to the entanglement observed in parametric down-conversion. A method of generating photon pairs from coherent pump light...

  4. MODELAMIENTO DE UN ALGORITMO PARA LA ASIGNACION DE LONGITUDES DE ONDA EN UN MULTIPLEXOR DWDM MINIMIZANDO EL PROCESO DE MEZCLADO DE LA CUARTA ONDA FWM (FOUR WAVE MIXING

    Directory of Open Access Journals (Sweden)

    Jorge Arturo Mojica Cáceres

    2013-07-01

    Full Text Available Uno de los medios de transmisión de alta velocidad más utilizados en nuestro entorno es la fibra óptica especificada en el estándar ITU-T G.625; sin embargo, su despliegue y utilización plantea en la actualidad varios desafíos a resolver debido a su característica de no linealidad, dentro de los cuales se encuentra el relacionado con la disminución del nivel de interferencia. Con el ánimo de brindar un aporte en la solución de esta problemática se propone modelar el comportamiento no lineal de FWM cuando se implementan sistemas de multiplexación de longitudes de onda por un único hilo de fibra óptica a fin de poder estimar las características fundamentales que rige esta tecnología y poder plantear un algoritmo que sea capaz de reducir la interferencia no lineal de cuarta onda (FWM. Como conclusión principal se encontró que el modelo propuesto reduce la interferencia no lineal FWM, lo que permite un aumento en la asignación de canales DWDM aumentando el ancho de banda establecido en cada enlace óptico.

  5. Transverse Field Dispersion in the Generalized Nonlinear Schrödinger Equation: Four Wave Mixing in a Higher Order Mode Fiber

    DEFF Research Database (Denmark)

    Pedersen, Martin Erland Vestergaard; Cheng, Ji; Xu, Chris

    2013-01-01

    An improved version of the generalized nonlinear Schrödinger equation is derived, which takes into account the correct dispersion of the transverse field distribution. The new improved version of the generalized nonlinear Schrödinger equation is verified to give the same results as the standard...

  6. Novel single/multiple wavelength RZ pulsesource based on Four-Wave Mixing in newly developed Highly Non-linear Fibre

    DEFF Research Database (Denmark)

    Grüner-Nielsen, L.; Clausen, Anders; Oxenløwe, Leif Katsuo

    2000-01-01

    A tuneable RZ-pulsesource over the entire EDFA gain bandwidth is proposed. The pulses show good performance in a transmission-experiment over 160 km Standard Single Mode Fibre and multiplexing/demultiplexing experiments. Expandable to a multiple RZ pulsesource....

  7. Mixed Aqueous Extract of Salvia Miltiorrhiza Reduces Blood Pressure through Inhibition of Vascular Remodelling and Oxidative Stress in Spontaneously Hypertensive Rats

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    2016-11-01

    Full Text Available Background/Aims: Salvia miltiorrhiza (SM contains four major aqueous active ingredients, which have been isolated, purified and identified as danshensu (DSS, salvianolic acid A (Sal-A, salvianolic acid B (Sal-B and protocatechuic aldehyde (PAL, totally abbreviated as SABP. Although SM is often used to treat various cardiovascular diseases in traditional Chinese medicine, the efficacy and function of optimal compatibility ratio of SM's active ingredients (SABP in the prevention and treatment of cardiovascular diseases remain uncertain. This study investigated antihypertensive effect and underlying mechanisms of SABP vs. SM lyophilized powder (SMLP in spontaneously hypertensive rats (SHR and to establish the ratio of the optimal compatibility of DSS, Sal-A, Sal-B and PAL in improving cardiovascular functions. Methods: The SHRs were treated with either SABP or SMLP and their systolic blood pressures (SBP were monitored. The isolated thoracic aorta of SHRs was segregated for immunohistochemistry, Hematoxylin-Eosin stain and mRNA and protein expression of NOX4, TGF-β1, Col-I, ET-1, α-SMA and Smad7. Moreover, the adventitial fibroblasts (AFs were isolated and cultured from SD rats' aorta and the reactive oxygen species (ROS production was determined after SABP or SMLP treatment. Results: SABP, but not SMLP, significantly reduced SBP, which were accompanied by the inhibited morphological changes in the thoracic aorta and the reduced mRNA and protein expression of NOX4, TGF-β1, Col-I, ET-1 and α-SMA, but the increased Smad 7 expression in SHRs. Moreover, SABP also resulted in a decreased ROS production in AFs of SD rats. Conclusions: These results indicate that SABP, but not SMLP, treatment potently inhibits hypertension through improvements of vascular remodeling and oxidative stress. The present study provides new evidence that the efficacy and function from optimal compatibility ratio of SM active ingredients is much better than its lyophilized

  8. Spontaneous hemoperitoneum.

    Science.gov (United States)

    Lucha, P A

    1996-06-01

    Massive hemoperitoneum seen without an obvious precipitating event is rare. A 21-year-old man was seen with diffuse abdominal pain of 48 hours' duration. He had no fever, nausea, or vomiting, and most laboratory values were normal. Exploration of the abdomen revealed free intraperitoneal blood with clotting but failed to reveal a source. The patient could recall no trauma or other inciting event. The only abnormalities found during laparotomy were multiple adhesions of the omentum to the lateral abdominal wall and localization of most of the clot within the greater omentum. The author cautions that a high index of suspicion followed by laparotomy are the management tools for controlling spontaneous hemoperitoneum. Conservative management produces a high mortality rate.

  9. Spontaneous Pneumothorax

    Directory of Open Access Journals (Sweden)

    John Costumbrado

    2017-09-01

    Full Text Available History of present illness: A 16-year-old male with asthma was brought to the emergency department by his parents for increasing right-sided chest pain associated with cough and mild dyspnea over the past week. Albuterol inhaler did not provide relief. He denied recent trauma, fever, sweats, and chills. The patient’s vitals and oxygen saturations were stable. Physical exam revealed a tall, slender body habitus with no signs of chest wall injuries. Bilateral breath sounds were present, but slightly diminished on the right. A chest radiograph was ordered to determine the etiology of the patient’s symptoms. Significant findings: Initial chest radiograph showed a 50% right-sided pneumothorax with no mediastinal shift, which can be identified by the sharp line representing the pleural lung edge (see arrows and lack of peripheral lung markings extending to the chest wall. While difficult to accurately estimate volume from a two-dimensional image, a 2 cm pneumothorax seen on chest radiograph correlates to approximately 50% volume.1 The patient underwent insertion of a pigtail pleural drain on the right and repeat chest radiograph showed resolution of previously seen pneumothorax. Ultimately the pigtail drain was removed and chest radiograph showed clear lung fields without evidence of residual pneumothorax or pleural effusion. Discussion: Pneumothorax is characterized by air between the lungs and the chest wall.2 Spontaneous pneumothorax (SP occurs when the pneumothorax is not due to trauma or any discernable etiology. 3 SP is multifactorial and may be associated with subpleural blebs, bullae, and other connective tissue changes that predispose the lungs to leak air into the pleural space.4 SP can be further subdivided into primary (no history of underlying lung disease or secondary (history of chronic obstructive pulmonary disease, tuberculosis, cystic fibrosis, lung malignancy, etc..2 It is estimated that the incidence of SP among US pediatric

  10. Measurements of Electric Field in a Nanosecond Pulse Discharge by 4-WAVE Mixing

    Science.gov (United States)

    Baratte, Edmond; Adamovich, Igor V.; Simeni Simeni, Marien; Frederickson, Kraig

    2017-06-01

    Picosecond four-wave mixing is used to measure temporally and Picosecond four-wave mixing is used to measure temporally and spatially resolved electric field in a nanosecond pulse dielectric discharge sustained in room air and in an atmospheric pressure hydrogen diffusion flame. Measurements of the electric field, and more precisely the reduced electric field (E/N) in the plasma is critical for determination rate coefficients of electron impact processes in the plasma, as well as for quantifying energy partition in the electric discharge among different molecular energy modes. The four-wave mixing measurements are performed using a collinear phase matching geometry, with nitrogen used as the probe species, at temporal resolution of about 2 ns . Absolute calibration is performed by measurement of a known electrostatic electric field. In the present experiments, the discharge is sustained between two stainless steel plate electrodes, each placed in a quartz sleeve, which greatly improves plasma uniformity. Our previous measurements of electric field in a nanosecond pulse dielectric barrier discharge by picosecond 4-wave mixing have been done in air at room temperature, in a discharge sustained between a razor edge high-voltage electrode and a plane grounded electrode (a quartz plate or a layer of distilled water). Electric field measurements in a flame, which is a high-temperature environment, are more challenging because the four-wave mixing signal is proportional to the to square root of the difference betwen the populations of N2 ground vibrational level (v=0) and first excited vibrational level (v=1). At high temperatures, the total number density is reduced, thus reducing absolute vibrational level populations of N2. Also, the signal is reduced further due to a wider distribution of N2 molecules over multiple rotational levels at higher temperatures, while the present four-wave mixing diagnostics is using spectrally narrow output of a ps laser and a high

  11. Spontaneous EEG activity and spontaneous emotion regulation.

    Science.gov (United States)

    Tortella-Feliu, M; Morillas-Romero, A; Balle, M; Llabrés, J; Bornas, X; Putman, P

    2014-12-01

    Variability in both frontal and parietal spontaneous EEG activity, using α and β band power and θ/β and δ/β ratios, was explored in a sample of 96 healthy volunteers as a potential correlate of individual differences in spontaneous emotion regulation (SER). Following a baseline EEG recording, participants were asked to continuously rate their discomfort while looking at affective pictures, as well as for a period of time after exposure. Greater spontaneous β band power in parietal locations, lower frontal and parietal δ/β ratios, and lower parietal θ/β ratio were associated with lower ratings of discomfort after the offset of unpleasant pictures. Moreover, lower parietal δ/β ratio was also related to less time needed to recover from discomfort after exposure to aversive pictures, while only a greater frontal and parietal α band power appeared to be associated with faster recovery from discomfort induced by normative-neutral pictures. However, parietal δ/β ratio was the only predictor of both minimum discomfort ratings and time needed to downregulate following exposure to unpleasant pictures, and frontal α band power the only spontaneous EEG index that predicted variability in spontaneous down-regulation after the exposure to normative-neutral pictures. Results are discussed focusing on the utility of diverse spontaneous EEG measures in several cortical regions when capturing trait-like individual differences in emotion regulation capabilities and processes. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Mixed biexcitons in single quantum wells

    DEFF Research Database (Denmark)

    Wagner, Hans Peter; Langbein, Wolfgang Werner; Hvam, Jørn Märcher

    1999-01-01

    Biexcitonic complexes in a ZnSe single quantum well are investigated by spectrally resolved four-wave mixing (FWM). The formation of heavy-heavy-hole XXh and of mixed heavy-light-hole XXm biexcitons showing binding energies of Delta(h) = 4.8 meV and Delta(m)= 2.8 meV is identified by polarization...... selection rules. The coherent dynamics of the FWM response and the observed FWM intensity ratio between the XXh and XXm biexciton-induced nonlinear signals are in agreement with the solution of an extended optical Bloch equation....

  13. Peritonitis - spontaneous bacterial

    Science.gov (United States)

    Spontaneous bacterial peritonitis (SBP); Ascites - peritonitis; Cirrhosis - peritonitis ... who are on peritoneal dialysis for kidney failure. Peritonitis may have other causes . These include infection from ...

  14. Spontaneous intracranial hypotension.

    LENUS (Irish Health Repository)

    Fullam, L

    2012-01-31

    INTRODUCTION: Spontaneous\\/primary intracranial hypotension is characterised by orthostatic headache and is associated with characteristic magnetic resonance imaging findings. CASE REPORT: We present a case report of a patient with typical symptoms and classical radiological images. DISCUSSION: Spontaneous intracranial hypotension is an under-recognised cause of headache and can be diagnosed by history of typical orthostatic headache and findings on MRI brain.

  15. Controlling spontaneous emission

    DEFF Research Database (Denmark)

    Lodahl, Peter

    Control over spontaneous emission of light is of great importance in quantum optics. It is essential for diverse applications such as miniature lasers, light-emitting diodes, and single-photon sources for quantum information. We present experimental studies on spontaneous emission of CdSe quantum...

  16. Spontaneous Resolution of Massive Spontaneous Tubercular Pneumothorax

    Science.gov (United States)

    Kant, Surya; Saheer, S.; Hassan, G.; Parengal, Jabeed

    2011-01-01

    A 29-year-old female presented with complaints of fever and productive cough of three weeks duration. Pulmonary tuberculosis was diagnosed bacteriologically and she was prescribed antituberculosis drugs. During follow-up she developed massive pneumothorax, for which patient refused surgical management and was managed conservatively. After six months there was complete spontaneous resolution of pneumothorax. The unusual presentation and unexpected outcome prompted us to report this case. PMID:22937428

  17. Spontaneous rupture of pyometra

    National Research Council Canada - National Science Library

    Mallah, Fatemeh; Eftekhar, Tahere; Naghavi-Behzad, Mohammad

    2013-01-01

    Spontaneous perforation is a very rare complication of pyometra. The clinical findings of perforated pyometra are similar to perforation of the gastrointestinal tract and other causes of acute abdomen...

  18. Spontaneous Perforation of Pyometra

    Directory of Open Access Journals (Sweden)

    Begüm Yildizhan

    2006-01-01

    Full Text Available Pyometra is the accumulation of purulent material in the uterine cavity. Its reported incidence is 0.01–0.5% in gynecologic patients; however, as far as elderly patients are concerned, its incidence is 13.6% [3]. The most common cause of pyometra is malignant diseases of genital tract and the consequences of their treatment (radiotherapy. Other causes are benign tumors like leiomyoma, endometrial polyps, senile cervicitis, cervical occlusion after surgery, puerperal infections, and congenital cervical anomalies. Spontaneous rupture of the uterus is an extremely rare complication of pyometra. To our knowledge, only 21 cases of spontaneous perforation of pyometra have been reported in English literature since 1980. This paper reports an additional case of spontaneous uterine rupture.

  19. Spontaneous renal artery dissection.

    Science.gov (United States)

    John, Santhosh G; Pillai, Unnikrishnan; Vaidyan, Philip B; Ishiyama, Takaaki

    2010-01-01

    Isolated spontaneous dissection of renal arteries or its branches are extremely rare. Most cases of renal artery dissection are associated with underlying pathology of the renal arteries. We report a case of spontaneous dissection of the left main renal artery and infarction of the left kidney with positive antiphospholipid antibody. Extensive work up of the patient including imaging studies confirmed the diagnosis of SRAD. Antiphospholipid antibodies may have a role in the pathogenesis of arterial dissection by causing endothelial dysfunction. This is a first literature report.

  20. Spontaneous Atraumatic Mediastinal Hemorrhage

    Directory of Open Access Journals (Sweden)

    Morkos Iskander BSc, BMBS, MRCS, PGCertMedEd

    2013-04-01

    Full Text Available Spontaneous atraumatic mediastinal hematomas are rare. We present a case of a previously fit and well middle-aged lady who presented with acute breathlessness and an increasing neck swelling and spontaneous neck bruising. On plain chest radiograph, widening of the mediastinum was noted. The bruising was later confirmed to be secondary to mediastinal hematoma. This life-threatening diagnostic conundrum was managed conservatively with a multidisciplinary team approach involving upper gastrointestinal and thoracic surgeons, gastroenterologists, radiologists, intensivists, and hematologists along with a variety of diagnostic modalities. A review of literature is also presented to help surgeons manage such challenging and complicated cases.

  1. SOLUTION DYNAMICS BY LINE-SHAPE ANALYSIS, RESONANCE LIGHT-SCATTERING AND FEMTOSECOND 4-WAVE-MIXING

    NARCIS (Netherlands)

    NIBBERING, ETJ; DUPPEN, K; WIERSMA, DA

    1992-01-01

    The results of line shape analysis, resonance light scattering and femtosecond four-wave mixing measurements are reported on several organic molecules in solution. It is shown that a Brownian oscillator model for line broadening provides a full description for the optical dynamics in aprotic

  2. Antenatal depressive symptoms as a predictor of deterioration in perceived social support across the perinatal period: a four-wave cohort study in Turkey.

    Science.gov (United States)

    Senturk, V; Abas, M; Dewey, M; Berksun, O; Stewart, R

    2017-03-01

    In a perinatal cohort of women in urban and rural Turkey, we investigated associations between antenatal depressive symptoms and subsequent changes in perceived quality of key family relationships. Of 730 women recruited in their third trimester (94.6% participation), 578 (79.2%) were reassessed at a mean of 4.1 (s.d. = 3.3) months after childbirth, 488 (66.8%) were reassessed at 13.7 (s.d. = 2.9) months, and 448 (61.4%) at 20.8 (s.d. = 2.7) months. At all four examinations, self-reported quality of relationship with the husband, mother and mother-in-law was ascertained using the Close Persons Questionnaire with respect to emotional support, practical support and negative aspects of the relationship. Antenatal depressive symptoms were defined using the Edinburgh Postnatal Depression Scale. A range of covariates in mixed models was considered including age, education, number of children, family structure, physical health, past emotional problems and stressful life events. Key findings were as follows: (i) reported emotional and practical support from all three relationships declined over time in the cohort overall; (ii) reported emotional support from the husband, and emotional and practical support from the mother-in-law, declined more strongly in women with antenatal depressive symptoms; (iii) associations between depressive symptoms and worsening spouse relationship were more pronounced in traditional compared with nuclear families. Antenatal depressive symptoms predicted marked decline in the quality of key relationships over the postnatal period. This may account for some of the contemporaneous associations between depression and worse social support, and may compound the risk of perinatal depression in subsequent pregnancies.

  3. Spontaneous uterine rupture

    African Journals Online (AJOL)

    had had hysteroscopy and repeated curettage7, but it happened during labor and not before labor as in our case. Diagnosis of spontaneous uterine rupture during pregnancy occuring on a scarred uterus can be made by ultrasound scan in which case there can be protrusion of membranes at the site of the scar8. If possible ...

  4. Spontaneous Appendicocutaneous Fistula I

    African Journals Online (AJOL)

    M T0k0de* MB, BS and. Dr 0. A. AWOj0bi+ FMCS (Nig). ABSTRACT. Ruptured appendicitis is not a common cause of spontaneous enterocutaneous fistula. A case of ruptured retrocaecal appendicitis presenting as an enterocutaneous fistula in a Nigerian woman is presented. The literature on this disorder is also reviewed.

  5. Spontaneous Grammar Explanations.

    Science.gov (United States)

    Tjoo, Hong Sing; Lewis, Marilyn

    1998-01-01

    Describes one New Zealand university language teacher's reflection on her own grammar explanations to university-level students of Bahasa Indonesian. Examines form-focused instruction through the teacher's spontaneous answers to students' questions about the form of the language they are studying. The teacher's experiences show that it takes time…

  6. Spontaneous rib fractures.

    Science.gov (United States)

    Katrancioglu, Ozgur; Akkas, Yucel; Arslan, Sulhattin; Sahin, Ekber

    2015-07-01

    Other than trauma, rib fracture can occur spontaneously due to a severe cough or sneeze. In this study, patients with spontaneous rib fractures were analyzed according to age, sex, underlying pathology, treatment, and complications. Twelve patients who presented between February 2009 and February 2011 with spontaneous rib fracture were reviewed retrospectively. The patients' data were evaluated according to anamnesis, physical examination, and chest radiographs. The ages of the patients ranged from 34 to 77 years (mean 55.91 ± 12.20 years), and 7 (58.4%) were male. All patients had severe cough and chest pain. The fractures were most frequently between 4th and 9th ribs; multiple rib fractures were detected in 5 (41.7%) patients. Eight (66.7%) patients had chronic obstructive pulmonary disease, 2 (16.7%) had bronchial asthma, and 2 (16.7%) had osteoporosis. Bone densitometry revealed a high risk of bone fracture in all patients. Patients with chronic obstructive pulmonary disease or bronchial asthma had been treated with high-dose steroids for over a year. Spontaneous rib fracture due to severe cough may occur in patients with osteoporosis, chronic obstructive pulmonary disease, or bronchial asthma, receiving long-term steroid therapy. If these patients have severe chest pain, chest radiography should be performed to check for bone lesions. © The Author(s) 2015.

  7. [Spontaneous bacterial peritonitis].

    Science.gov (United States)

    Velkey, Bálint; Vitális, Eszter; Vitális, Zsuzsanna

    2017-01-01

    Spontaneous bacterial peritonitis occurs most commonly in cirrhotic patients with ascites. Pathogens get into the circulation by intestinal translocation and colonize in peritoneal fluid. Diagnosis of spontaneous bacterial peritonitis is based on elevated polymorphonuclear leukocyte count in the ascites (>0,25 G/L). Ascites culture is often negative but aids to get information about antibiotic sensitivity in positive cases. Treatment in stable patient can be intravenous then orally administrated ciprofloxacin or amoxicillin/clavulanic acid, while in severe cases intravenous III. generation cephalosporin. Nosocomial spontaneous bacterial peritonitis often caused by Gram-positive bacteria and multi-resistant pathogens can also be expected thus carbapenem should be the choice of the empiric treatment. Antibiotic prophylaxis should be considered. Norfloxacin is used most commonly, but changes are expected due to increase in quinolone resistance. As a primary prophylaxis, a short-term antibiotic treatment is recommended after gastrointestinal bleeding for 5 days, while long-term prophylaxis is for patients with low ascites protein, and advanced disease (400 mg/day). Secondary prophylaxis is recommended for all patients recovered from spontaneous bacterial peritonitis. Due to increasing antibiotic use of antibiotics prophylaxis is debated to some degree. Orv. Hetil., 2017, 158(2), 50-57.

  8. [Augmented spontaneous breathing].

    Science.gov (United States)

    Hachenberg, T

    1996-09-01

    Impaired pulmonary gas exchange can result from lung parenchymal failure inducing oxygenation deficiency and fatigue of the respiratory muscles, which is characterized by hypercapnia or a combination of both mechanisms. Contractility of and coordination between the diaphragm and the thoracoabdominal respiratory muscles predominantly determine the efficiency of spontaneous breathing. Sepsis, cardiac failure, malnutrition or acute changes of the load conditions may induce fatigue of the respiratory muscles. Augmentation of spontaneous breathing is not only achieved by the application of different technical principles or devices; it also has to improve perfusion, metabolism, load conditions and contractility of the respiratory muscles. Intermittent mandatory ventilation (IMV) allows spontaneous breathing of the patient and augments alveolar ventilation by periodically applying positive airway pressure tidal volumes, which are generated by the respirator. Potential advantages include lower mean airway pressure (PAW), as compared with controlled mechanical ventilation, and improved haemodynamics. Suboptimal IMV systems may impose increased work and oxygen cost of breathing, fatigue of the respiratory muscles and CO2 retention. During pressure support ventilation (PSV), inspiratory alterations of PAW or gas flow (trigger) are detected by the respirator, which delivers a gas flow to maintain PAW at a fixed value (usually 5-20 cm H2O) during inspiration. PSV may be combined with other modalities of respiratory therapy such as IMV or CPAP. Claimed advantages of PSV include decreased effort of breathing, reduced systemic and respiratory muscle consumption of oxygen, prophylaxis of diaphragmatic fatigue and an improved extubation rate after prolonged periods of mechanical ventilation. Minimum alveolar ventilation is not guaranteed during PSV; thus, close observation of the patient is mandatory to avoid serious respiratory complications. Continuous positive airway pressure

  9. Spontaneous recovery from acalculia.

    Science.gov (United States)

    Basso, Anna; Caporali, Alessandra; Faglioni, Pietro

    2005-01-01

    A topic much considered in research on acalculia was its relationship with aphasia. Far less attention has been given to the natural course of acalculia. In this retrospective study, we examined the relationship between aphasia and acalculia in an unselected series of 98 left-brain-damaged patients and the spontaneous recovery from acalculia in 92 acalculic patients with follow-up. There was a significant association between aphasia and acalculia although 19 participants exhibited aphasia with no acalculia and six acalculia with no aphasia. We observed significant improvement between a first examination carried out between 1 and 5 months post-onset and a second examination carried out between 3 and 11 months later (mean: 5 months). The mechanisms of spontaneous recovery are discussed.

  10. Spontaneous Rupture of Pyometra

    Directory of Open Access Journals (Sweden)

    Fatemeh Mallah

    2013-01-01

    Full Text Available Spontaneous perforation is a very rare complication of pyometra. The clinical findings of perforated pyometra are similar to perforation of the gastrointestinal tract and other causes of acute abdomen. In most cases, a correct and definite diagnosis can be made only by laparotomy. We report two cases of diffuse peritonitis caused by spontaneous perforated pyometra. The first case is a 78-year-old woman with abdominal pain for which laparotomy was performed because of suspected incarcerated hernia. The second case is a 61-year-old woman with abdominal pain for which laparotomy was performed because of symptoms of peritonitis. At laparotomy of both cases, 1 liter of pus with the source of uterine was found in the abdominal cavity. The ruptured uterine is also detected. More investigations revealed no malignancy as the reason of the pyometra.

  11. [Spontaneous pneumothorax in children].

    Science.gov (United States)

    Michel, J L

    2000-03-01

    Spontaneous pneumothorax is rare in childhood. Before 12 years of age the main underlying pathologies are asthma, cystic malformations, post infectious bullae, and infectious pneumoniae. After 12 years of age it is mainly associated with cystic fibrosis and constitutional slim morphology. Symptoms vary according to the extent of lung collapse and the diagnosis is confirmed on chest X rays. In mildly symptomatic pneumothorax, spontaneous resolution is achieved within few days. When cardiorespiratory difficulties are present, mechanical evacuation of air from the pleural cavity is necessary through a tube drainage maintained until complete pulmonary reexpansion. Surgical treatment is indicated in case of persisting air leakage after one week of efficient drainage, large cystic malformation or post infectious bullae, recurring or bilateral pneumothorax.

  12. [Spontaneous bilateral Petit hernia].

    Science.gov (United States)

    Fontoura, Rodrigo Dias; Araújo, Emerson Silveira de; Oliveira, Gustavo Alves de; Sarmenghi Filho, Deolindo; Kalil, Mitre

    2011-01-01

    Petit's lumbar hernia is an uncommon defect of the posterior abdominal wall that represents less than 1% of all abdominal wall hernias. It is more often unilateral and founded in young females, rarely containing a real herniated sac. There are two different approaches to repair: laparoscopy and open surgery. The goal of this article is to report one case of spontaneous bilateral lumbar Petit's hernia treated with open surgery.

  13. Spontaneous spinal epidural abscess.

    LENUS (Irish Health Repository)

    Ellanti, P

    2011-10-01

    Spinal epidural abscess is an uncommon entity, the frequency of which is increasing. They occur spontaneously or as a complication of intervention. The classical triad of fever, back pain and neurological symptoms are not always present. High index of suspicion is key to diagnosis. Any delay in diagnosis and treatment can have significant neurological consequences. We present the case of a previously well man with a one month history of back pain resulting from an epidural abscess.

  14. Spontaneous Perforation of Pyometra

    OpenAIRE

    Sharma, Nalini; Singh, Ahanthem Santa; Bhaphiralyne, Wankhar

    2016-01-01

    Pyometra is collection of purulent material which occurs when there is interference with its normal drainage. It is an uncommon condition with incidence of 0.1 to 0.5% of all gynecological patients. Spontaneous rupture of uterus is an extremely rare complication of pyometra. A 65-year-old lady presented with pain abdomen and purulent vaginal discharge. Preoperative diagnosis of pyometra was made by magnetic resonance imaging (MRI). Laparotomy followed by peritoneal lavage and repair of perfor...

  15. Optical frequency mixing at coupled gold nanoparticles.

    Science.gov (United States)

    Danckwerts, Matthias; Novotny, Lukas

    2007-01-12

    We present nonlinear-optical four-wave mixing (4WM) at coupled gold nanoparticles. By decreasing the interparticle distance from large separation to touching contact, the 4WM yield increases by 4 orders of magnitude. The reason for this dramatic enhancement lies in the shift of the localized plasmon resonance to infrared wavelengths as the dimer is formed, making one of the input wavelengths doubly resonant. At the touching point, the 4WM signal changes discontinuously because of a sudden charge redistribution imposed by the formation of a conductive bridge. The 4-wave mixing signal provides an ultrasensitive measure for the contact point between a pair of particles and it can be employed as a spatially and temporally controllable photon source.

  16. Bilateral spontaneous hemotympanum: Case report

    Directory of Open Access Journals (Sweden)

    Economou Nicolas C

    2006-10-01

    Full Text Available Abstract Background The most common causes of hemotympanum are therapeutic nasal packing, epistaxis, blood disorders and blunt trauma to the head. Hemotympanum is characterized as idiopathic, when it is detected in the presence of chronic otitis media. A rare case of spontaneous bilateral hemotympanum in a patient treated with anticoagulants is presented herein. Case presentation A 72-year-old male presented with acute deterioration of hearing. In the patient's medical history aortic valve replacement 1 year before presentation was reported. Since then he had been administered regularly coumarinic anticoagulants, with INR levels maintained between 3.4 and 4.0. Otoscopy revealed the presence of bilateral hemotympanum. The audiogram showed symmetrical moderately severe mixed hearing loss bilaterally, with the conductive component predominating. Tympanograms were flat bilaterally with absent acoustic reflexes. A computerized tomography scan showed the presence of fluid in the mastoid and middle ear bilaterally. Treatment was conservative and consisted of a 10-day course of antibiotics, anticongestants and temporary interruption of the anticoagulant therapy. After 3 weeks, normal tympanic membranes were found and hearing had returned to previous levels. Conclusion Anticoagulant intake should be included in the differential diagnosis of hemotympanum, because its detection and appropriate treatment may lead to resolution of the disorder.

  17. Nonlinear spatial mode imaging of hybrid photonic crystal fibers

    DEFF Research Database (Denmark)

    Petersen, Sidsel Rübner; Alkeskjold, Thomas Tanggaard; Laurila, Marko

    2013-01-01

    Degenerate spontaneous four wave mixing is studied for the rst time in a large mode area hybrid photonic crystal ber, where light con nement is achieved by combined index- and bandgap guiding. Four wave mixing products are generated on the edges of the bandgaps, which is veri ed by numerical...

  18. Spontaneous Thigh Compartment Syndrome

    Directory of Open Access Journals (Sweden)

    Khan, Sameer K

    2011-02-01

    Full Text Available A young man presented with a painful and swollen thigh, without any history of trauma, illness, coagulopathic medication or recent exertional exercise. Preliminary imaging delineated a haematoma in the anterior thigh, without any fractures or muscle trauma. Emergent fasciotomies were performed. No pathology could be identified intra-operatively, or on follow-up imaging. A review of thigh compartment syndromes described in literature is presented in a table. Emergency physicians and traumatologists should be cognisant of spontaneous atraumatic presentations of thigh compartment syndrome, to ensure prompt referral and definitive management of this limb-threatening condition. [West J Emerg Med. 2011;12(1:134-138].

  19. High-resolution inverse Raman and resonant-wave-mixing spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rahn, L.A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    These research activities consist of high-resolution inverse Raman spectroscopy (IRS) and resonant wave-mixing spectroscopy to support the development of nonlinear-optical techniques for temperature and concentration measurements in combustion research. Objectives of this work include development of spectral models of important molecular species needed to perform coherent anti-Stokes Raman spectroscopy (CARS) measurements and the investigation of new nonlinear-optical processes as potential diagnostic techniques. Some of the techniques being investigated include frequency-degenerate and nearly frequency-degenerate resonant four-wave-mixing (DFWM and NDFWM), and resonant multi-wave mixing (RMWM).

  20. Spying on spontaneous combustion

    Energy Technology Data Exchange (ETDEWEB)

    1994-11-01

    The British Coal Technical Services and Research Executive (TSRE) has carried out a project to investigate potential applications of fibre optic based distributed temperature sensing (DTS) technology within a mining environment. The objective was to determine whether DTS could identify and locate spontaneous combustion earlier than conventional systems. The trials took place in a British mine from April to September 1992 and from August to November 1993 using a commercially available system from York Sensors Ltd. Results indicate that DTS is capable of very sensitive temperature monitoring, revealing sub-degree thermal trends resulting from various activities and local heatings. DTS has several prospective mining applications, e.g. monitoring known hot spots, investigating ventilation and heat flow through mine workings. The trials show that the system can be installed, calibrated, operated and maintained by relatively inexperienced personnel. 1 photo.

  1. Screening for spontaneous preterm birth

    NARCIS (Netherlands)

    van Os, M.A.; van Dam, A.J.E.M.

    2015-01-01

    Preterm birth is the most important cause of perinatal morbidity and mortality worldwide. In this thesis studies on spontaneous preterm birth are presented. The main objective was to investigate the predictive capacity of mid-trimester cervical length measurement for spontaneous preterm birth in a

  2. Observation of Bs mixing

    CERN Multimedia

    CERN. Geneva

    2007-01-01

    A peculiar and most important property of Bs mesons is that they transform spontaneously into their own antiparticles, and back again. These transitions, known as flavor oscillations or mixing, are extremely rapid, rendering their measurement a very challenging experimental task. The determination of the Bs oscillation frequency is, at the same time, of great interest for constraining elements of the Standard Model CKM matrix and its unitarity. Large samples of Bs mesons collected by the CDF and D0 experiments operating at the Fermilab Tevatron have recently yielded unprecedented results, which are here reported. Emphasis is given to details of the analysis developed at CDF, presenting the observation of Bs mixing, the precise measurement of the oscillation frequency, and a discussion of its impact on the description of the flavor sector.

  3. Spontaneous intracranial hypotension

    Energy Technology Data Exchange (ETDEWEB)

    Haritanti, A. [Department of Radiology, Aristotele' s University School of Medicine, AHEPA University Hospital, 54636 Thessaloniki (Greece); Karacostas, D. [Department of Neurology, Aristotele' s University School of Medicine, AHEPA University Hospital, 54636 Thessaloniki (Greece)], E-mail: bneurol@med.auth.gr; Drevelengas, A. [Department of Radiology, Aristotele' s University School of Medicine, AHEPA University Hospital, 54636 Thessaloniki (Greece); Kanellopoulos, V. [Department of Radiology, Aristotele' s University School of Medicine, AHEPA University Hospital, 54636 Thessaloniki (Greece)], E-mail: vasikanel@hotmail.com; Paraskevopoulou, E. [Department of Neurology, Aristotele' s University School of Medicine, AHEPA University Hospital, 54636 Thessaloniki (Greece); Lefkopoulos, A.; Economou, I.; Dimitriadis, A.S. [Department of Radiology, Aristotele' s University School of Medicine, AHEPA University Hospital, 54636 Thessaloniki (Greece)

    2009-02-15

    Spontaneous intracranial hypotension (SIH) is an uncommon but increasingly recognized syndrome. Orthostatic headache with typical findings on magnetic resonance imaging (MRI) are the key to diagnosis. Delayed diagnosis of this condition may subject patients to unnecessary procedures and prolong morbidity. We describe six patients with SIH and outline the important clinical and neuroimaging findings. They were all relatively young, 20-54 years old, with clearly orthostatic headache, minimal neurological signs (only abducent nerve paresis in two) and diffuse pachymeningeal gadolinium enhancement on brain MRI, while two of them presented subdural hygromas. Spinal MRI was helpful in detecting a cervical cerebrospinal fluid leak in three patients and dilatation of the vertebral venous plexus with extradural fluid collection in another. Conservative management resulted in rapid resolution of symptoms in five patients (10 days-3 weeks) and in one who developed cerebral venous sinus thrombosis, the condition resolved in 2 months. However, this rapid clinical improvement was not accompanied by an analogous regression of the brain MR findings that persisted on a longer follow-up. Along with recent literature data, our patients further point out that SIH, to be correctly diagnosed, necessitates increased alertness by the attending physician, in the evaluation of headaches.

  4. Spontaneous Intracapsular Tonsillar Hemorrhage

    Directory of Open Access Journals (Sweden)

    Güçlü Beriat

    2012-07-01

    Full Text Available In this case report, we discussed a case of spontaneous intracapsular tonsillar haemorrhage appearing as a tumor medial to the left palatine tonsil and clinging to the tonsillar tissue with a pedicle. The patient was a 30 years old healthy pregnant woman. She had a growing sensation of a lump in her oropharynx and dysphagia in the past three months. She had no history of acute and chronic tonsillitis or trauma. On examination, a mobile brown mass with a 2 cm diameter having a small pedicle at the upper pole of the left palatine tonsil was seen. Other laboratory results were normal. The mass was excised under general anesthesia. Histological evaluation revealed tonsillar intracapsular bleeding with lymphoepi-thelial tissue and acute hemorrhagic fields bounded by a capsule. A postpartum tonsillectomy was planned for our patient. Tonsillectomy must be performed to patients followed up with this diagnosis in order to differentiate between dyspha-gia, risks of bleeding and aspiration, and malignant tumors.

  5. Patient satisfaction with antiretroviral services at primary health-care facilities in the Free State, South Africa – a two-year study using four waves of cross-sectional data

    Directory of Open Access Journals (Sweden)

    Meulemans Herman

    2008-10-01

    Full Text Available Abstract Background The study's first objective was to determine the levels of patient satisfaction with services at antiretroviral treatment (ART assessment sites. Differences in patient satisfaction with several aspects of service over time and among health districts were measured. The second objective was to examine the association between human resource shortages and levels of patient satisfaction with services. Methods Four cross-sectional waves of data were collected from a random sample of 975 patients enrolled in the Free State's public-sector ART programme. One-way analysis of variance (ANOVA with the Bonferroni adjustment for multiple comparisons was used to assess the differences in patient satisfaction among the Province's five districts and among the four waves of data. Correlation coefficient analysis using Pearson's r was used to assess the association between ART nurse vacancy rates and patient satisfaction with the services provided by nurses over time. Results With respect to both general services and the services provided by nurses, our results indicate high overall satisfaction among Free State patients receiving public-sector ART. However, our data present a less positive picture of patient satisfaction with waiting times. Patients in Fezile Dabi District were generally slightly dissatisfied with the waiting times at their assessment sites. In fact, waiting times at assessment sites were the most important predictor of discontent among ART patients. Significant geographical (P P r = -0.438, P Conclusion Collectively, our findings show high levels of patient satisfaction with ART-related services, but also confirm claims by other studies, which have identified human resource shortages as the most important obstacle to a successful South African AIDS strategy.

  6. Ziprasidone-induced spontaneous orgasm.

    Science.gov (United States)

    Boora, K; Chiappone, K; Dubovsky, S; Xu, J

    2010-06-01

    Neuroleptic treatment in schizophrenic patients has been associated with sexual dysfunction, including impotence and decreased libido. Spontaneous ejaculation without sexual arousal during typical antipsychotic treatment is a rare condition that has been described with zuclopentixol, trifluoperazine, and thiothixene. Here, we are reporting a case of spontaneous orgasm with ziprasidone in a bipolar patient. This patient began to repeatedly experience spontaneous sexual arousal and orgasm, which she had never experienced in the past. Ziprasidone might be causing an increase in sexual orgasm by 5-HT2 receptor antagonism, which preclinical evidence suggests that it facilitates dopamine release in the cortex.

  7. Spontaneous intraorbital hematoma: case report

    Directory of Open Access Journals (Sweden)

    Vinodan Paramanathan

    2010-12-01

    Full Text Available Vinodan Paramanathan, Ardalan ZolnourianQueen's Hospital NHS Foundation Trust, Burton on Trent, Staffordshire DE13 0RB, UKAbstract: Spontaneous intraorbital hematoma is an uncommon clinical entity seen in ophthalmology practice. It is poorly represented in the literature. Current evidence attributes it to orbital trauma, neoplasm, vascular malformations, acute sinusitis, and systemic abnormalities. A 65-year-old female presented with spontaneous intraorbital hematoma manifesting as severe ocular pains, eyelid edema, proptosis, and diplopia, without a history of trauma. Computer tomography demonstrated a fairly well defined extraconal lesion with opacification of the paranasal sinuses. The principal differential based on all findings was that of a spreading sinus infection and an extraconal tumor. An unprecedented finding of a spontaneous orbital hematoma was discovered when the patient was taken to theater. We discuss the rarity of this condition and its management.Keywords: hemorrhage, ophthalmology, spontaneous, intra-orbital, hematoma

  8. Spontaneous ischaemic stroke in dogs

    DEFF Research Database (Denmark)

    Gredal, Hanne Birgit; Skerritt, G. C.; Gideon, P.

    2013-01-01

    Translation of experimental stroke research into the clinical setting is often unsuccessful. Novel approaches are therefore desirable. As humans, pet dogs suffer from spontaneous ischaemic stroke and may hence offer new ways of studying genuine stroke injury mechanisms.......Translation of experimental stroke research into the clinical setting is often unsuccessful. Novel approaches are therefore desirable. As humans, pet dogs suffer from spontaneous ischaemic stroke and may hence offer new ways of studying genuine stroke injury mechanisms....

  9. Spontaneous closure of midline diastema following frenectomy.

    Science.gov (United States)

    Koora, Kiran; Muthu, M S; Rathna, Prabhu V

    2007-03-01

    Maxillary midline diastema is a common aesthetic problem in mixed and early permanent dentitions. The space can occur either as a transient malocclusion or created by developmental, pathological or iatrogenical factors. Many innovative therapies varying from restorative procedures such as composite build-up to surgery (frenectomies) and orthodontics are available. Although literature says every frenectomy procedure should be preceded by orthodontic treatment, we opted for frenectomy technique without any orthodontic intervention. Presented herewith is a case report of a 9-year-old girl with a high frenal attachment that had caused spacing of the maxillary central incisors. A spontaneous closure of the midline diastema was noted within 2 months following frenectomy. The patient was followed up for 4 months after which the space remained closed and there was no necessity for an orthodontic treatment at a later stage.

  10. Spontaneous closure of midline diastema following frenectomy

    Directory of Open Access Journals (Sweden)

    Koora Kiran

    2007-03-01

    Full Text Available Maxillary midline diastema is a common aesthetic problem in mixed and early permanent dentitions. The space can occur either as a transient malocclusion or created by developmental, pathological or iatrogenical factors. Many innovative therapies varying from restorative procedures such as composite build-up to surgery (frenectomies and orthodontics are available. Although literature says every frenectomy procedure should be preceded by orthodontic treatment, we opted for frenectomy technique without any orthodontic intervention. Presented herewith is a case report of a 9-year-old girl with a high frenal attachment that had caused spacing of the maxillary central incisors. A spontaneous closure of the midline diastema was noted within 2 months following frenectomy. The patient was followed up for 4 months after which the space remained closed and there was no necessity for an orthodontic treatment at a later stage.

  11. Quantum Measurement Driven by Spontaneous Symmetry Breaking

    Science.gov (United States)

    Morikawa, M.; Nakamichi, A.

    2006-10-01

    Quantum mechanics cannot be applied within a closed system. Inevitable measurement process in quantum mechanics is usually treated separately from the basic principles of the framework and requires outside observer of the system. In this paper, we propose that the quantum measurement process is actually a physical process associated with the ubiquitous mechanism of spontaneous symmetry breaking. Based on this proposal, we construct a quantum measurement model in which the mixed state evolves into a pure state as the dynamical pro-coherence process. Furthermore, the classically distinguishable pointer parameter emerges as the c-number order parameter in the formalism of closed time-path quantum field theory. We also discuss the precision of the measurement and the possible deduction of the Born probability postulate.

  12. The Relationship among Spontaneity, Impulsivity, and Creativity

    Science.gov (United States)

    Kipper, David A.; Green, Doreen J.; Prorak, Amanda

    2010-01-01

    The present study was designed to investigate two characteristics of spontaneity, its relationship to creativity and to impulsivity. We hypothesized a positive relationship between spontaneity and creativity, consistent with Moreno, 1953 "canon of spontaneity-creativity." We also predicted a negative relationship between spontaneity and…

  13. Optical antenna enhanced spontaneous emission.

    Science.gov (United States)

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

    2015-02-10

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

  14. Pseudoarachnoiditis in Spontaneous Intracranial Hypotension

    Directory of Open Access Journals (Sweden)

    Özlem Alkan

    2011-03-01

    Full Text Available Spontaneous intracranial hypotension is an important cause of new daily persistent headaches in young and middle-aged individuals. The diagnosis is made based on low cerebrospinal fluid pressure with characteristic findings upon brain and spinal magnetic resonance imaging (MRI. We present the case of a 15-year-old boy with spontaneous intracranial hypotension. Although his brain MRI was normal, his lumbar spinal MRI showed clustering of the nerve roots characteristic of arachnoiditis. Radionuclide cisternography revealed an epidural leak, which was treated with an epidural blood patch. The patient reached a near-full recovery within 24 h, and the lumbar spinal MRI findings mimicking arachnoiditis disappeared.

  15. Spontaneous waves in muscle fibres

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, Stefan; Kruse, Karsten [Department of Theoretical Physics, Saarland University, 66041 Saarbruecken (Germany); Max Planck Institute for the Physics of Complex Systems, Noethnitzer Street 38, 01187 Dresden (Germany)

    2007-11-15

    Mechanical oscillations are important for many cellular processes, e.g. the beating of cilia and flagella or the sensation of sound by hair cells. These dynamic states originate from spontaneous oscillations of molecular motors. A particularly clear example of such oscillations has been observed in muscle fibers under non-physiological conditions. In that case, motor oscillations lead to contraction waves along the fiber. By a macroscopic analysis of muscle fiber dynamics we find that the spontaneous waves involve non-hydrodynamic modes. A simple microscopic model of sarcomere dynamics highlights mechanical aspects of the motor dynamics and fits with the experimental observations.

  16. Spontaneous isolated celiac artery dissection

    Directory of Open Access Journals (Sweden)

    Tuba Cimilli Ozturk

    2011-01-01

    Full Text Available Dyspepsia with mild, stabbing epigastric discomfort without history of trauma is a very common symptom that emergency physicians see in their daily practice. Vascular emergencies, mostly the aortic dissection and aneurysm, are always described in the differential diagnosis with persistent symptoms. Isolated celiac artery dissection occurring spontaneously is a very rare diagnosis. The involvement of branch vessels is generally observed and patients show various clinical signs and symptoms according to the involved branch vessel. Here we are presenting a case with spontaneous isolated celiac artery dissection, without any branch vessel involvement or visceral damage, detected by computed tomography scans taken on admission.

  17. Spontaneous breakdown and the scalar nonet

    Energy Technology Data Exchange (ETDEWEB)

    Scadron, M.D.

    1982-07-01

    In the context of the QCD quark model and on the basis of dynamical Bethe-Salpeter ladder graphs, we suggest that (i) the existence of the scalar q-barq hadron multiplet, like the pseudoscalar q-barq multiplet, is a direct consequence of dynamical spontaneous breakdown of chiral symmetry with a chiral-limiting nonstrange mass scale of m/sub sigmaNS//sup CL/ = 2m/sub dyn/ roughly-equal630 MeV, (ii) the lifting of the nonstrange sigma-delta degeneracy is expected from the s-wave quark-gluon annihilation diagram, and (iii) the observed sigma-S* mixing follows from the existence of the p-wave scalar quark-annihilation diagram. The resulting predicted 0q-barq nonet is then sigma(750 MeV), kappa(800), S*(980), and delta(985), in agreement with data for the resonant masses, the mixing angle, and also decay widths except for the kappa(800).

  18. Biomarkers of spontaneous preterm birth

    DEFF Research Database (Denmark)

    Polettini, Jossimara; Cobo, Teresa; Kacerovsky, Marian

    2017-01-01

    Despite decades of research on risk indicators of spontaneous preterm birth (PTB), reliable biomarkers are still not available to screen or diagnose high-risk pregnancies. Several biomarkers in maternal and fetal compartments have been mechanistically linked to PTB, but none of them are reliable...

  19. THE RATE OF SPONTANEOUS MUTATION

    Indian Academy of Sciences (India)

    The Rate of Spontaneous Mutation of a Human Gene. (Published on 1935 J. Genet. 31, 317-326). J. B. S. Haldane. J. Genet. Classic Volume 83 Issue 3 December 2004 pp 235-244. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/jgen/083/03/0235-0244. Author Affiliations.

  20. Spontaneously disappearing lumbar disc protrusion

    OpenAIRE

    Ushewokunze, Shungu; Abbas, Naeem; Dardis, Ronan; Killeen, Ian

    2008-01-01

    Spontaneous disappearance of a herniated lumbar disc is known to occur. This case study describes a 45-year-old patient whose symptoms of lumbar radiculopathy resolved and follow-up imaging showed complete disappearance of the disc prolapse. This phenomenon strengthens the role of conservative treatment in the management of lumbar disc protrusions.

  1. Spontaneous fission of superheavy nuclei

    Indian Academy of Sciences (India)

    and penetrability for binary nuclear configurations typical for fission processes. The deformed two- ... Finally, the WKB method is used to calculate penetrabilities and spontaneous fission half-lives. Calculations ... the mass tensor components contain binary character of the process, because the pairing. Pramana – J. Phys.

  2. Shell theorem for spontaneous emission

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; Mortensen, Jakob Egeberg; Lodahl, Peter

    2013-01-01

    and therefore is given exactly by the dipole approximation theory. This surprising result is a spontaneous emission counterpart to the shell theorems of classical mechanics and electrostatics and provides insights into the physics of mesoscopic emitters as well as great simplifications in practical calculations....

  3. Spontaneous complete chorioamniotic membrane separation ...

    African Journals Online (AJOL)

    Apart from the association with Down syndrome, other complications include preterm labour, premature rupture of membranes, IUGR, fetal malformation and fetal death. Such pregnancies require close fetal surveillance and occasionally inpatient management. Case: We present a case of spontaneous complete CAS and ...

  4. Prediction of Spontaneous Preterm Birth

    NARCIS (Netherlands)

    Dijkstra, Karolien

    2002-01-01

    Preterm birth is a leading cause of neonatal morbidity and mortality. It is a major goal in obstetrics to lower the incidence of spontaneous preterm birth (SPB) and related neonatal morbidity and mortality. One of the principal objectives is to discover early markers that would allow us to identify

  5. Silicosis with bilateral spontaneous pneumothorax

    Directory of Open Access Journals (Sweden)

    Fotedar Sanjay

    2010-01-01

    Full Text Available Presentation with simultaneous bilateral pneumothorax is uncommon and usually in the context of secondary spontaneous pneumothorax.The association of pneumothorax and silicosis is infrequent and most cases are unilateral. Bilateral pneumothorax in silicosis is very rare with just a few reports in medical literature.

  6. Experiments on Detection of Voiced Hesitations in Russian Spontaneous Speech

    Directory of Open Access Journals (Sweden)

    Vasilisa Verkhodanova

    2016-01-01

    Full Text Available The development and popularity of voice-user interfaces made spontaneous speech processing an important research field. One of the main focus areas in this field is automatic speech recognition (ASR that enables the recognition and translation of spoken language into text by computers. However, ASR systems often work less efficiently for spontaneous than for read speech, since the former differs from any other type of speech in many ways. And the presence of speech disfluencies is its prominent characteristic. These phenomena are an important feature in human-human communication and at the same time they are a challenging obstacle for the speech processing tasks. In this paper we address an issue of voiced hesitations (filled pauses and sound lengthenings detection in Russian spontaneous speech by utilizing different machine learning techniques, from grid search and gradient descent in rule-based approaches to such data-driven ones as ELM and SVM based on the automatically extracted acoustic features. Experimental results on the mixed and quality diverse corpus of spontaneous Russian speech indicate the efficiency of the techniques for the task in question, with SVM outperforming other methods.

  7. Spontaneous Wave Generation from Submesoscale Fronts and Filaments

    Science.gov (United States)

    Shakespeare, C. J.; Hogg, A.

    2016-02-01

    Submesoscale features such as eddies, fronts, jets and filaments can be significant sources of spontaneous wave generation at the ocean surface. Unlike near-inertial waves forced by winds, these spontaneous waves are typically of higher frequency and can propagate through the thermocline, whereupon they break and drive mixing in the ocean interior. Here we investigate the spontaneous generation, propagation and subsequent breaking of these waves using a combination of theory and submesoscale resolving numerical models. The mechanism of generation is nearly identical to that of lee waves where flow is deflected over a rigid obstacle on the sea floor. Here, very sharp fronts and filaments of order 100m width moving in the submesoscale surface flow generate "surface lee waves" by presenting an obstacle to the surrounding stratified fluid. Using our numerical model we quantify the net downward wave energy flux from the surface, and where it is dissipated in the water column. Our results suggest an alternative to the classical paradigm where the energy associated with mixing in the ocean interior is sourced from bottom-generated lee waves.

  8. Spontaneous Retropharyngeal Emphysema: A Case Report | Chi ...

    African Journals Online (AJOL)

    ... is a rare clinical condition in pediatric otolaryngology. The predominant symptoms are sore throat, odynophagia, dysphagia, and neck pain. Here, we report a case of spontaneous retropharyngeal emphysema. Keywords: Iatrogenic injury, retropharyngeal emphysema, spontaneous retropharyngeal emphysem, trauma ...

  9. Lunar Cycle Influences Spontaneous Delivery in Cows

    OpenAIRE

    Yonezawa, Tomohiro; Uchida, Mona; Tomioka, Michiko; Matsuki, Naoaki

    2016-01-01

    There is a popular belief that the lunar cycle influences spontaneous delivery in both humans and cattle. To assess this relationship, we investigated the synodic distribution of spontaneous deliveries in domestic Holstein cows. We used retrospective data from 428 spontaneous, full-term deliveries within a three-year period derived from the calving records of a private farm in Hokkaido, Japan. Spontaneous birth frequency increased uniformly from the new moon to the full moon phase and decreas...

  10. The moral significance of spontaneous abortion.

    OpenAIRE

    Murphy, T F

    1985-01-01

    Spontaneous abortion is rarely addressed in moral evaluations of abortion. Indeed, 'abortion' is virtually always taken to mean only induced abortion. After a brief review of medical aspects of spontaneous abortion, I attempt to articulate the moral implications of spontaneous abortion for the two poles of the abortion debate, the strong pro-abortion and the strong anti-abortion positions. I claim that spontaneous abortion has no moral relevance for strict pro-abortion positions but that the ...

  11. Mixed Movements

    DEFF Research Database (Denmark)

    Brabrand, Helle

    2010-01-01

    levels than those related to building, and this exploration is a special challenge and competence implicit artistic development work. The project Mixed Movements generates drawing-material, not primary as representation, but as a performance-based media, making the body being-in-the-media felt and appear......Mixed Movements is a research project engaged in performance-based architectural drawing. Architectonic implementation questions relations between the human body and a body of architecture by the different ways we handle drawing materials. A drawing may explore architectonic problems at other...

  12. Spontaneous Photon Emission in Cavities

    Directory of Open Access Journals (Sweden)

    Alber G.

    2014-01-01

    Full Text Available We investigate spontaneous photon emission processes of two-level atoms in parabolic and ellipsoidal cavities thereby taking into account the full multimode scenario. In particular, we calculate the excitation probabilities of the atoms and the energy density of the resulting few-photon electromagnetic radiation field by using semiclassical methods for the description of the multimode scenario. Based on this approach photon path representations are developed for relevant transition probability amplitudes which are valid in the optical frequency regime where the dipole and the rotating-wave approximations apply. Comparisons with numerical results demonstrate the quality of these semiclassical results even in cases in which the wave length of a spontaneously emitted photon becomes comparable or even larger than characteristic length scales of the cavity. This is the dynamical regime in which diffraction effects become important so that geometric optical considerations are typically not applicable.

  13. Spontaneous rupture of the ureter

    Science.gov (United States)

    Eken, Alper; Akbas, Tugana; Arpaci, Taner

    2015-01-01

    Spontaneous rupture of the ureter is a very rare condition and usually results from ureteral obstruction by a calculus. Only theoretical mecha­nisms have been proposed and no possible explanation has yet been reported in the literature. Intravenous contrast-enhanced computed tomography is the most informative study with high sensitivity. Treatment should be individualised, and depends on the state of the patient. Minimally invasive endourological procedures with double-J catheter placement and percutaneous drainage offer excellent results. Conservative management with analgesics and antibiotic coverage may be an alternative to surgery. Herein, we present a case of spontaneous rupture of the proximal ureter with no evidence of an underlying pathological condition. PMID:25715862

  14. Spontaneous regression of colon cancer.

    Science.gov (United States)

    Kihara, Kyoichi; Fujita, Shin; Ohshiro, Taihei; Yamamoto, Seiichiro; Sekine, Shigeki

    2015-01-01

    A case of spontaneous regression of transverse colon cancer is reported. A 64-year-old man was diagnosed as having cancer of the transverse colon at a local hospital. Initial and second colonoscopy examinations revealed a typical cancer of the transverse colon, which was diagnosed as moderately differentiated adenocarcinoma. The patient underwent right hemicolectomy 6 weeks after the initial colonoscopy. The resected specimen showed only a scar at the tumor site, and no cancerous tissue was proven histologically. The patient is alive with no evidence of recurrence 1 year after surgery. Although an antitumor immune response is the most likely explanation, the exact nature of the phenomenon was unclear. We describe this rare case and review the literature pertaining to spontaneous regression of colorectal cancer. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. Spontaneous Rotational Inversion in Phycomyces

    KAUST Repository

    Goriely, Alain

    2011-03-01

    The filamentary fungus Phycomyces blakesleeanus undergoes a series of remarkable transitions during aerial growth. During what is known as the stagea IV growth phase, the fungus extends while rotating in a counterclockwise manner when viewed from above (stagea IVa) and then, while continuing to grow, spontaneously reverses to a clockwise rotation (stagea IVb). This phase lasts for 24-48Ah and is sometimes followed by yet another reversal (stageAIVc) before the overall growth ends. Here, we propose a continuum mechanical model of this entire process using nonlinear, anisotropic, elasticity and show how helical anisotropy associated with the cell wall structure can induce spontaneous rotation and, under appropriate circumstances, the observed reversal of rotational handedness. © 2011 American Physical Society.

  16. Spontaneous Perforation of Rectosigmoid Colon

    Directory of Open Access Journals (Sweden)

    Farhad Haj Sheikholeslami

    2010-12-01

    Full Text Available Spontaneous perforation of the sigmoid colon or rectom is definedas a sudden perforation of the colon in the absence of diseasessuch as tumors, diverticulosis or external injury. It is avery rare finding, and if neglected, results in severe peritonitisand high mortality. The causes of this rare condition are numerous,and in this case it might be due to the chronic constipationinduced by an anticholinergic antipsychotic.Iran J Med Sci 2010; 35(4: 339-341.

  17. Spontaneous esophageal-pleural fistula

    Directory of Open Access Journals (Sweden)

    Sameer Vyas

    2011-01-01

    Full Text Available Spontaneous esophageal-pleural fistula (EPF is a rare entity. We describe a case in a middle-aged female who presented with severe retrosternal chest pain and shortness of breadth. Chest computed tomography showed right EPF and hydropneumothorax. She was managed conservatively keeping the chest tube drainage and performing feeding jejunostomy. A brief review of the imaging finding and management of EPF is discussed.

  18. Study of spontaneous fission lifetimes using nuclear density functional theory

    Directory of Open Access Journals (Sweden)

    Sadhukhan Jhilam

    2013-12-01

    Full Text Available The spontaneous fission lifetimes have been studied microscopically by minimizing the collective action integral in a two-dimensional collective space of quadrupole moments (Q20, Q22 representing elongation and triaxiality. The microscopic collective potential and inertia tensor are obtained by solving the self-consistent Hartree-Fock-Bogoliubov (HFB equations with the Skyrme energy density functional and mixed pairing interaction. The mass tensor is computed within the perturbative Adiabatic Time-Dependent HFB (ATDHFB approach in the cranking approximation. The dynamic fission trajectories have been obtained by minimizing the collective action using two different numerical techniques. The values of spontaneous fission lifetimes obtained in this way are compared with the static results.

  19. Spontaneous Splenic Rupture in Melanoma

    Directory of Open Access Journals (Sweden)

    Hadi Mirfazaelian

    2014-01-01

    Full Text Available Spontaneous rupture of spleen due to malignant melanoma is a rare situation, with only a few case reports in the literature. This study reports a previously healthy, 30-year-old man who came with chief complaint of acute abdominal pain to emergency room. On physical examination, abdominal tenderness and guarding were detected to be coincident with hypotension. Ultrasonography revealed mild splenomegaly with moderate free fluid in abdominopelvic cavity. Considering acute abdominal pain and hemodynamic instability, he underwent splenectomy with splenic rupture as the source of bleeding. Histologic examination showed diffuse infiltration by tumor. Immunohistochemical study (positive for S100, HMB45, and vimentin and negative for CK, CD10, CK20, CK7, CD30, LCA, EMA, and chromogranin confirmed metastatic malignant melanoma. On further questioning, there was a past history of a nasal dark skin lesion which was removed two years ago with no pathologic examination. Spontaneous (nontraumatic rupture of spleen is an uncommon situation and it happens very rarely due to neoplastic metastasis. Metastasis of malignant melanoma is one of the rare causes of the spontaneous rupture of spleen.

  20. Competition between atomic coherence and electromagnetically induced population grating in multi-wave mixing

    Science.gov (United States)

    Lou, Lin; Sun, Jia; Feng, Weikang; Wu, Zhenkun; Zhang, Yiqi; Zhang, Yanpeng

    2014-12-01

    We study the competition and transfer between atomic coherence and electromagnetically induced population grating of multi-wave mixing (MWM) in four- and five-level atomic systems. The MWM signal falls into a new type electromagnetically induced transparency (EIT) window that depends on propagating directions of the related fields rather than atomic system configuration. By blocking different coupling laser beams, we experimentally distinguish different wave mixing processes. In addition, by changing the detuning of pump beams, we can observe double peaks for both EIT and MWM signals. The results may have potential applications in correlated photon-pair generations in four-wave mixing as well as six-wave mixing and quantum information processing.

  1. Wave-mixing solitons in ferroelectric crystals

    Science.gov (United States)

    Bugaychuk, S.; Kovacs, L.; Mandula, G.; Polgar, K.; Rupp, R. A.

    Although the sine-Gordon equation was originally obtained for the description of four-wave mixing in transmission geometry, it describes self-diffraction of the wave from shifted gratings as well. The sine-Gordon equation governs soliton propagation. The photoinduced amplitude of the refractive-index grating exhibits also a soliton shape in the crystal volume. The origin of this effect is the change of the contrast of light due to energy transfer between coupled waves during their propagation, which occurs in bulk crystals with strong photorefractive gain. The theoretical description shows the possibility to control the soliton properties by changing the input intensity ratio and/or input phase difference of the wave. The effect can lead to diffraction efficiency management, auto-oscillations and bistability of the output waves due to wave-mixing in ferroelectrics. Results on the first experimental observation of non-uniform distribution of the grating amplitude profile and its changes versus input intensity ratio are presented.

  2. Mixed parentage

    DEFF Research Database (Denmark)

    Bang Appel, Helene; Singla, Rashmi

    2016-01-01

    Despite an increase in cross border intimate relationships and children of mixed parentage, there is little mention or scholarship about them in the area of childhood and migrancy in the Nordic countries. The international literature implies historical pathologisation, contestation and current...

  3. Mixed segmentation

    DEFF Research Database (Denmark)

    Hansen, Allan Grutt; Bonde, Anders; Aagaard, Morten

    This book is about using recent developments in the fields of data analytics and data visualization to frame new ways of identifying target groups in media communication. Based on a mixed-methods approach, the authors combine psychophysiological monitoring (galvanic skin response) with textual...

  4. Treatment of Chronic Spontaneous Urticaria

    Science.gov (United States)

    2012-01-01

    Chronic spontaneous urticaria is defined as persistent symptoms of urticaria for 6 weeks or more. It is associated with autoimmunity in approximately 45 percent of patients. Therapy is often difficult however the initial approach should employ high-dose non-sedating antihistamines; 4-6 tablets/day may be necessary. It has been shown that the response to 4 tablets/day exceeds 3, and exceeds 2, which exceeds 1. However the dose that corresponds to the maximal dose of first generation antihistamines (hydroxyzine, diphenhydramine) used previously, is 6/day. Yet over half the patients are refractory to antihistamines and other agents should be tried next. Whereas current guidelines (published) often add leukotriene antagonists and/or H2 receptor antogonists next, these are of little utility. Likewise drugs effective for urticarial vasculitis (colchicine, dapsone, sulfasalazine, hydroxychloroquine) are effective in a small percentage of patients and no study suggests that the response rate of any of them exceeds the 30% placebo responses seen in most double-blind, placebo controlled studies. The drugs that are effective for antihistamine-resistant chronic spontaneous urticaria are corticosteroids, cyclosporine, and Omalizumab. Use of steroids is limited by toxicity. If used at all, a dose of no more than 10 mg/day should be employed with a weekly reduction of 1 mg. The response rates to cyclosporine and Omalizumab are each close to 75%. Cyclosporine can be used effectively if care is taken to monitor blood pressure, urine protein, blood urea nitrogen, and creatinine, every 6 weeks. Omalizumab has the best profile in terms of efficacy/toxicity and, once approved by federal agencies for use in chronic spontaneous urticaria, a dramatic change in the treatment paradigm, whether associated with autoimmunity or not, is predicted. A phase 3 trial is currently in place. Refractoriness to both Omalizumab and cyclosporine is expected to be less than 5 percent of patients. Other

  5. Spontaneous Biliary Peritonitis in Children

    Directory of Open Access Journals (Sweden)

    Supreethi Kohli

    2013-01-01

    Full Text Available Pediatric Spontaneous Bile duct perforation is a rare clinical condition with only around 150 cases reported worldwide. Early management gives excellent prognosis but the condition often presents a diagnostic dilemma. Hepato-biliary Technetium-99m-iminodiacetic acid scintiscan is the diagnostic investigation of choice but its availability in third world countries is limited. We present two cases of spontaneous biliary peritonitis in children, which were diagnosed without scintiscanning. The first case was a one-and -a half-year-old child, who was diagnosed with biliary peritonitis without pneumoperitoneum by a combination of Ultrasound (USG, Contrast enhanced computed tomography (CECT, and Magnetic Resonance Imaging (MRI. The child underwent USG-guided drainage and subsequent cholecystectomy with hepatico-jejunostomy. The second child also had biliary peritonitis without pneumoperitoneum, which was initially suspected on USG. CECT revealed dilated gall bladder and fluid collection in sub-hepatic space and pelvis. Abdominal paracentesis revealed presence of bile. The child responded to conservative therapy. Both are doing well on two-year follow-up. In a patient with jaundice, biliary tract abnormalities and/or free fluid, either generalized or localized to peri-cholecystic/sub-hepatic space on USG/CT/MRI, in the absence of pneumoperitoneum, suggest a diagnosis of biliary perforation even in the absence of scintiscanning.

  6. A Case of Multiple Spontaneous Keloid Scars

    Directory of Open Access Journals (Sweden)

    Abdulhadi Jfri

    2015-07-01

    Full Text Available Keloid scars result from an abnormal healing response to cutaneous injury or inflammation that extends beyond the borders of the original wound. Spontaneous keloid scars forming in the absence of any previous trauma or surgical procedure are rare. Certain syndromes have been associated with this phenomenon, and few reports have discussed the evidence of single spontaneous keloid scar, which raises the question whether they are really spontaneous. Here, we present a 27-year-old mentally retarded single female with orbital hypertelorism, broad nasal bridge, repaired cleft lip and high-arched palate who presented with progressive multiple spontaneous keloid scars in different parts of her body which were confirmed histologically by the presence of typical keloidal collagen. This report supports the fact that keloid scars can appear spontaneously and are possibly linked to a genetic factor. Furthermore, it describes a new presentation of spontaneous keloid scars in the form of multiple large lesions in different sites of the body.

  7. Spontaneous Uterine Perforation of Pyometra Presenting as Acute Abdomen

    Directory of Open Access Journals (Sweden)

    Toshihiro Kitai

    2014-01-01

    Full Text Available Pyometra is the accumulation of pus in the uterine cavity, and spontaneous perforation of pyometra resulting in generalized diffuse peritonitis is extremely uncommon. We report a rare case of diffuse peritonitis caused by spontaneous perforation of pyometra. A 66-year-old postmenopausal woman with diffuse abdominal pain and vomiting was admitted to our institution. She had a history of mixed connective-tissue disease and had been taking steroids for 20 years. Under a diagnosis of generalized peritonitis secondary to perforation of the gastrointestinal tract or uterus, supravaginal hysterectomy and bilateral salpingo-oophorectomy were performed. Unfortunately, wound dehiscence and infection occurred during the postoperative course, which were exacerbated by her immunocompromised state. Despite intensive care and a course of antibiotics, the patient died of multiple organ failure resulting from sepsis on the 36th postoperative day. Although correct diagnosis, early intervention, and proper treatment can reduce morbidity and mortality of spontaneous perforation of pyometra, if severe infection occurs, this disease can be life threatening for immunocompromised hosts.

  8. Multiphoton laser wave-mixing absorption spectroscopy for samarium using a graphite furnace atomizer

    Energy Technology Data Exchange (ETDEWEB)

    Maniaci, Michael J.; Tong, William G. E-mail: william.tong@sdsu.edu

    2004-07-30

    Nonlinear laser wave-mixing optical technique is presented as a sensitive atomic spectroscopic method for the analysis of rare earth elements using an unmodified commercially available graphite furnace (GF) atomizer. A simple nonplanar backward-scattering degenerate four-wave mixing optical arrangement offers sub-picogram detection sensitivity with sub-Doppler Lorentzian-broadened resolution. Nonlinear wave mixing is an unusually sensitive absorption-based optical method that offers both excellent detection sensitivity and sub-Doppler spectral resolution. A mass detection limit of 0.7 pg and a concentration detection limit of 70 pg/ml are determined for a rare earth element, samarium, using the 429.7-nm excitation line.

  9. Spontaneous germinal centers and autoimmunity.

    Science.gov (United States)

    Domeier, Phillip P; Schell, Stephanie L; Rahman, Ziaur S M

    2017-02-01

    Germinal centers (GCs) are dynamic microenvironments that form in the secondary lymphoid organs and generate somatically mutated high-affinity antibodies necessary to establish an effective humoral immune response. Tight regulation of GC responses is critical for maintaining self-tolerance. GCs can arise in the absence of purposeful immunization or overt infection (called spontaneous GCs, Spt-GCs). In autoimmune-prone mice and patients with autoimmune disease, aberrant regulation of Spt-GCs is thought to promote the development of somatically mutated pathogenic autoantibodies and the subsequent development of autoimmunity. The mechanisms that control the formation of Spt-GCs and promote systemic autoimmune diseases remain an open question and the focus of ongoing studies. Here, we discuss the most current studies on the role of Spt-GCs in autoimmunity.

  10. Detailed description of spontaneous emission

    Science.gov (United States)

    Guryev, M. V.

    2012-08-01

    The wave side of wave-photon duality, describing light as an electromagnetic field (EMF), is used in this article. The EMF of spontaneous light emission (SE) of a laser-excited atom is calculated from first principles for the first time. This calculation is done using the simple method of atomic quantum electrodynamics. The EMF of SE is also calculated for three types of polyatomic light sources excited by a laser. It is shown that light radiated by such sources can be coherent, which explains recent experiments on SE of laser-excited atoms. Small sources of SE can be superradiant, which also conforms to experiment. Thus, SE is shown not to be a random event itself. Random properties of natural light are simply explained as a result of thermal excitation randomness without additional hypotheses. The EMF of SE is described by simple complex functions, but not real ones.

  11. Crows spontaneously exhibit analogical reasoning.

    Science.gov (United States)

    Smirnova, Anna; Zorina, Zoya; Obozova, Tanya; Wasserman, Edward

    2015-01-19

    Analogical reasoning is vital to advanced cognition and behavioral adaptation. Many theorists deem analogical thinking to be uniquely human and to be foundational to categorization, creative problem solving, and scientific discovery. Comparative psychologists have long been interested in the species generality of analogical reasoning, but they initially found it difficult to obtain empirical support for such thinking in nonhuman animals (for pioneering efforts, see [2, 3]). Researchers have since mustered considerable evidence and argument that relational matching-to-sample (RMTS) effectively captures the essence of analogy, in which the relevant logical arguments are presented visually. In RMTS, choice of test pair BB would be correct if the sample pair were AA, whereas choice of test pair EF would be correct if the sample pair were CD. Critically, no items in the correct test pair physically match items in the sample pair, thus demanding that only relational sameness or differentness is available to support accurate choice responding. Initial evidence suggested that only humans and apes can successfully learn RMTS with pairs of sample and test items; however, monkeys have subsequently done so. Here, we report that crows too exhibit relational matching behavior. Even more importantly, crows spontaneously display relational responding without ever having been trained on RMTS; they had only been trained on identity matching-to-sample (IMTS). Such robust and uninstructed relational matching behavior represents the most convincing evidence yet of analogical reasoning in a nonprimate species, as apes alone have spontaneously exhibited RMTS behavior after only IMTS training. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Children's Spontaneous Vocalisations during Play: Aesthetic Dimensions

    Science.gov (United States)

    Countryman, June; Gabriel, Martha; Thompson, Katherine

    2016-01-01

    This paper explores the phenomenon of spontaneous vocalisations in the self-chosen, unstructured outdoor play of children aged 3-12. Spontaneous vocalisations encompass the whole range of children's unprompted, natural, expressive vocal soundings beyond spoken language. Non-participant observations at childcare centres and on elementary school…

  13. The spontaneous in the therapeutic theater

    OpenAIRE

    Silva, Marisa Schmidt

    2012-01-01

    The author makes considerations about the historic influences on the creation of Spontaneous theater by Jacob Levy Moreno and the psychotherapy conditions of this theater, nowadays revigoratade in whole world. The author consider the specific way to deal with Spontaneous theater of "Troupe de Psicodramatores" in Curitiba, Parana.

  14. A new class of spontaneously polarized materials

    DEFF Research Database (Denmark)

    Field, David; Plekan, Oksana; Cassidy, Andrew

    2011-01-01

    Very large electric fields form spontaneously within films of seemingly prosaic chemicals such as nitrous oxide or propane.We describe how the discovery of this unexpected phenomenon took place and how we attempt to understand the nature of the new class of spontaneously polarized materials...

  15. Spontaneous Achilles tendon rupture in alkaptonuria | Mohammed ...

    African Journals Online (AJOL)

    Spontaneous Achilles tendon ruptures are uncommon. We present a 46-year-old man with spontaneous Achilles tendon rupture due to ochronosis. To our knowledge, this has not been previously reported in Sudan literature. The tendon of the reported patient healed well after debridement and primary repairs.

  16. Mathematical models of spontaneous symmetry breaking

    OpenAIRE

    Sardanashvily, G.

    2008-01-01

    The Higgs mechanism of mass generation is the main ingredient in the contemporary Standard Model and its various generalizations. However, there is no comprehensive theory of spontaneous symmetry breaking. We summarize the relevant mathematical results characterizing spontaneous symmetry breaking phenomena in algebraic quantum theory, axiomatic quantum field theory, group theory, and classical gauge theory.

  17. Spontaneous CP violation and CPT violation

    OpenAIRE

    Qian, Yu Kun

    2011-01-01

    At first we give a little formalism to show some features of spontaneous CP violation theory. Then we give a convincing argument show that Cronin etc's experiment is a evidence of CPT violation and spontaneous CP violation is absolutely necessary. Final we discuss some possible CPT violation mechanism.

  18. Spontaneous emission in nanoscopic dielectric particles.

    Science.gov (United States)

    Rogobete, Lavinia; Schniepp, Hannes; Sandoghdar, Vahid; Henkel, Carsten

    2003-10-01

    We report on theoretical studies of the inhibition of the spontaneous emission process in subwavelength dielectric media. We discuss the modification of the spontaneous emission rate as a function of the size and shape of the medium as well as the position of the emitter in it.

  19. Spontaneity and Equilibrium II: Multireaction Systems

    Science.gov (United States)

    Raff, Lionel M.

    2014-01-01

    The thermodynamic criteria for spontaneity and equilibrium in multireaction systems are developed and discussed. When N reactions are occurring simultaneously, it is shown that G and A will depend upon N independent reaction coordinates, ?a (a = 1,2, ..., N), in addition to T and p for G or T and V for A. The general criteria for spontaneity and…

  20. Spontaneous Retroperitoneal Hematoma: A Rare Devastating ...

    African Journals Online (AJOL)

    Spontaneous Retroperitoneal Hematoma: A Rare Devastating. Clinical Entity of a Pleiada of Less Common Origins. Definition of Wunderlich syndrome, also known as spontaneous retroperitoneal hemorrhage. (SRH), was first given in 1700 by ... of SRH as a complication of tumors, however, is low. In renal cell carcinoma, ...

  1. Spontaneous rupture of choledochal cyst: case report

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Ho Seob; Nam, Kyung Jin; Lee, Jin Hwa; Kim, Chan Sung; Choi, Jong Cheol; Oh, Jong Young [Dong-a University College of Medicine, Pusan (Korea, Republic of)

    2002-11-01

    Spontaneous rupture of a choledochal cyst leading to biliary peritonitis is a rare complication which can be fatal if not promptly diagnosed. The authors report the ultrasound and CT findings of two cases of spontaneous choledochal cystic rupture and the biliary peritonitis which ensued.

  2. Spontaneous pneumomediastinum after bench press training.

    Science.gov (United States)

    Nishino, Tomoya

    2017-04-01

    Spontaneous pneumomediastinum is often associated with asthma and mainly affects adolescent males with a tall, thin body habitus. A 17-year-old man complained of chest and pharyngeal pain after bench press training and spontaneous pneumomediastinum was diagnosed. It should be considered in the differential diagnosis of chest pain of uncertain cause.

  3. Early pregnancy angiogenic markers and spontaneous abortion

    DEFF Research Database (Denmark)

    Andersen, Louise B; Dechend, Ralf; Karumanchi, S Ananth

    2016-01-01

    BACKGROUND: Spontaneous abortion is the most commonly observed adverse pregnancy outcome. The angiogenic factors soluble Fms-like kinase 1 and placental growth factor are critical for normal pregnancy and may be associated to spontaneous abortion. OBJECTIVE: We investigated the association between...... maternal serum concentrations of soluble Fms-like kinase 1 and placental growth factor, and subsequent spontaneous abortion. STUDY DESIGN: In the prospective observational Odense Child Cohort, 1676 pregnant women donated serum in early pregnancy, gestational week ..., interquartile range 71-103). Concentrations of soluble Fms-like kinase 1 and placental growth factor were determined with novel automated assays. Spontaneous abortion was defined as complete or incomplete spontaneous abortion, missed abortion, or blighted ovum

  4. The (perceived) meaning of spontaneous thoughts.

    Science.gov (United States)

    Morewedge, Carey K; Giblin, Colleen E; Norton, Michael I

    2014-08-01

    Spontaneous thoughts, the output of a broad category of uncontrolled and inaccessible higher order mental processes, arise frequently in everyday life. The seeming randomness by which spontaneous thoughts arise might give people good reason to dismiss them as meaningless. We suggest that it is precisely the lack of control over and access to the processes by which they arise that leads people to perceive spontaneous thoughts as revealing meaningful self-insight. Consequently, spontaneous thoughts potently influence judgment. A series of experiments provides evidence supporting two hypotheses. First, we hypothesize that the more a thought is perceived to be spontaneous, the more it is perceived to provide meaningful self-insight. Participants perceived more spontaneous kinds of thought (e.g., intuition) to reveal greater self-insight than did more controlled kinds of thought in Study 1 (e.g., deliberation). In Studies 2 and 3, participants perceived thoughts with the same content and target to reveal greater self-insight when spontaneously rather than deliberately generated (i.e., childhood memories and impressions formed). Second, we hypothesize that the greater self-insight attributed to thoughts that are (perceived to be) spontaneous leads those thoughts to more potently influence judgment. Participants felt more sexually attracted to an attractive person whom they thought of spontaneously than deliberately in Study 4, and reported their commitment to a current romantic relationship would be more affected by the spontaneous rather than deliberate recollection of a good or bad experience with their romantic partner in Study 5. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  5. Spontaneous hemopneumothorax: our experience with surgical management.

    Science.gov (United States)

    Tay, Cheong Kiat Julian; Yee, Yong Chen; Asmat, Atasha

    2015-03-01

    Spontaneous hemopneumothorax is rare, accounting for only 1%-12% of patients presenting with spontaneous pneumothorax. The optimal management of these patients remains controversial with no definitive guidelines on patient selection and timing of surgery. The aim of this study was to review our institution's surgical experience in the management of patients with spontaneous hemopneumothorax. We performed a retrospective review of all patients with spontaneous hemopneumothorax who underwent surgery from January 2000 to June 2013. Patient data were obtained from our institution's primary spontaneous pneumothorax database. Of 510 patients who underwent surgery for spontaneous pneumothorax, 33 (6.4%) developed spontaneous hemopneumothorax. The mean age was 24.0 years (range 16-40 years). In 30 (90.9%) patients, it was their first presentation of pneumothorax. There were 25 (75.8%) patients with Vanderschueren stage III spontaneous pneumothorax. Blood loss ranged from 250 to 3000 mL (mean 1280 mL). In 28 patients, a torn adhesion band was the source of bleeding. Thoracotomy was the surgical approach in 9 (27.3%) patients, and video-assisted thoracic surgery was used in 24 (72.7%). One patient required reoperation for retained clots. There was no mortality. Our results suggest that surgical management of spontaneous hemopneumothorax can be undertaken with minimal morbidity and mortality. With the increasing use of video-assisted thoracic surgery, definitive surgical management of spontaneous hemopneumothorax can be instituted earlier. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  6. Spontaneous prosocial choice by chimpanzees.

    Science.gov (United States)

    Horner, Victoria; Carter, J Devyn; Suchak, Malini; de Waal, Frans B M

    2011-08-16

    The study of human and primate altruism faces an evolutionary anomaly: There is ample evidence for altruistic preferences in our own species and growing evidence in monkeys, but one of our closest relatives, the chimpanzee (Pan troglodytes), is viewed as a reluctant altruist, acting only in response to pressure and solicitation. Although chimpanzee prosocial behavior has been reported both in observational captive studies and in the wild, thus far Prosocial Choice Tests have failed to produce evidence. However, methodologies of previous Prosocial Choice Tests may have handicapped the apes unintentionally. Here we present findings of a paradigm in which chimpanzees chose between two differently colored tokens: one "selfish" token resulting in a reward for the actor only (1/0), and the other "prosocial" token rewarding both the actor and a partner (1/1). Seven female chimpanzees, each tested with three different partners, showed a significant bias for the prosocial option. Prosocial choices occurred both in response to solicitation by the partner and spontaneously without solicitation. However, directed requests and pressure by the partner reduced the actor's prosocial tendency. These results draw into question previous conclusions indicating that chimpanzees have a limited sensitivity to the needs of others and behave prosocially only in response to significant prompting.

  7. STUDENTS’ SPONTANEOUS SMILE IN EFL CLASSROOM

    Directory of Open Access Journals (Sweden)

    Daniela Gomes de Araújo Nóbrega

    2012-12-01

    Full Text Available This article discusses the importance of the students’ spontaneous smile in EFL classroom interaction, and its implication to their oral production. Findings proved that the students’ spontaneous smile served as a fundamental interactive nonverbal sign for it not only favors a closer relation among students, but also helps them in the co-construction of oral activities in group works. In sum, the students’ spontaneous smile appeared to be a nonverbal indicative of proximity and of increasing oral interaction among them.

  8. Herpetic viruses and spontaneous recovery in melanoma.

    Science.gov (United States)

    Motofei, I G

    1996-08-01

    The malignant melanoma may display extremely variable forms of development, from clinical forms with a lethal course to the unforeseeable situations of spontaneous cures. The basic immunotherapeutic procedures, as well as hypotheses regarding the mechanisms involved in courses towards spontaneous regressions, are presented. Since viruses of the herpes genus are involved in the mechanisms assumed to be at the basis of spontaneous regressions, it is suggested that these viruses (selected strains) be used in the clinic, in order to check the advanced hypothesis, an opportunity which could permit to study also the very probable therapeutic alternative offered by this virus, namely the association of the well-known immunotherapeutic methods.

  9. Clock frequency estimation under spontaneous emission

    Science.gov (United States)

    Qin, Xi-Zhou; Huang, Jia-Hao; Zhong, Hong-Hua; Lee, Chaohong

    2018-02-01

    We investigate the quantum dynamics of a driven two-level system under spontaneous emission and its application in clock frequency estimation. By using the Lindblad equation to describe the system, we analytically obtain its exact solutions, which show three different regimes: Rabi oscillation, damped oscillation, and overdamped decay. From the analytical solutions, we explore how the spontaneous emission affects the clock frequency estimation. We find that under a moderate spontaneous emission rate, the transition frequency can still be inferred from the Rabi oscillation. Our results enable potential practical applications in frequency measurement and quantum control under decoherence.

  10. Spontaneous emission from active dielectric microstructures

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Tromborg, Bjarne

    2001-01-01

    Spontaneous emission is one of the key factors that determine the noise properties of photonic devices and the pump power threshold of lasers. The spontaneous emission in dielectric microstructures (micro-cavities, photonic crystals, optical waveguides, etc.) can to some extend be controlled...... and engineered due to the dependence of the emission rate on the location and polarisation of the emitters in the structure. This paper addresses the methods of quantum electrodynamics of dielectric media which enable calculation of the local rate of spontaneous emission in active microstructures....

  11. Spontaneous Bacterial Peritonitis in Subclinical Hypothyroidism

    Directory of Open Access Journals (Sweden)

    Dalip Gupta

    2013-11-01

    Full Text Available Hypothyroidism is an uncommon cause of ascites. Here we describe a case of a 75 year-old female patient with spontaneous bacterial peritonitis and subclinical hypothyroidism that resolved with thyroid replacement and antibiotic therapy respectively. Ascitic fluid analysis revealed a gram-positive bacterium on gram staining. A review of the literature revealed just one other reported case of myxoedema ascites with concomitant spontaneous bacterial peritonitis and no case has till been reported of spontaneous bacterial peritonitis in subclinical hypothyroidism.

  12. Ultrasonographic features of spontaneous breast tumor infarction.

    Science.gov (United States)

    Oh, Hyeon Jeong; Kim, Sung Hun; Kang, Bong Joo; Lee, A Won; Song, Byung Joo; Kim, Hyen Sook; Cha, Eun Suk

    2015-11-01

    The aim of this paper is to evaluate the ultrasonographic features of spontaneous breast tumor infarction. The pathologic information system database of the Department of Radiology was retrospectively searched. Between 2009 and 2011, nine cases in eight patients were pathologically confirmed as spontaneous breast tumor infarctions. Mammographic images and the ultrasonographic images were acquired. Two other radiologists analyzed the mammographic and ultrasonographic findings. Most common features were oval, indistinct, heterogeneously hypoechoic mass with posterior enhancement. All lesions were classified as C4 (suspicious finding) except one case. Spontaneous breast tumor infarction should be included in the differential diagnoses of hetereogeneously hypoechoic suspicious solid lesions mimicking malignancy.

  13. Does Spontaneous Favorability to Power (vs. Universalism) Values Predict Spontaneous Prejudice and Discrimination?

    Science.gov (United States)

    Souchon, Nicolas; Maio, Gregory R; Hanel, Paul H P; Bardin, Brigitte

    2017-10-01

    We conducted five studies testing whether an implicit measure of favorability toward power over universalism values predicts spontaneous prejudice and discrimination. Studies 1 (N = 192) and 2 (N = 86) examined correlations between spontaneous favorability toward power (vs. universalism) values, achievement (vs. benevolence) values, and a spontaneous measure of prejudice toward ethnic minorities. Study 3 (N = 159) tested whether conditioning participants to associate power values with positive adjectives and universalism values with negative adjectives (or inversely) affects spontaneous prejudice. Study 4 (N = 95) tested whether decision bias toward female handball players could be predicted by spontaneous attitude toward power (vs. universalism) values. Study 5 (N = 123) examined correlations between spontaneous attitude toward power (vs. universalism) values, spontaneous importance toward power (vs. universalism) values, and spontaneous prejudice toward Black African people. Spontaneous positivity toward power (vs. universalism) values was associated with spontaneous negativity toward minorities and predicted gender bias in a decision task, whereas the explicit measures did not. These results indicate that the implicit assessment of evaluative responses attached to human values helps to model value-attitude-behavior relations. © 2016 The Authors. Journal of Personality Published by Wiley Periodicals, Inc.

  14. [Ischemic stroke related to spontaneous].

    Science.gov (United States)

    Benamer, H; Bouzid, M A; Dufay, A; Akodad, M; Russel, S; Halna du Fretay, X; Haziza, F

    2017-12-01

    Cardiovascular disease in women is a particularly complex pathology especially in the youngest population. The clinical presentation of acute coronary syndromes is sometimes misleading and does not necessarily point to the potential presence of cardiac disease given the frequent absence of cardiovascular risks. Such complexity results in delayed diagnosis, which worsens the outcome of myocardial infarction and generates complications related to the absence of coronary revascularization. We report the case of a patient who suffered an (undiagnosed) apical myocardial infarction that went undetected and was complicated by a voluminous intraventricular thrombus with embolus migration in the cerebral circulation resulting in an ischemic accident. The combination of these two pathologies make their therapeutic management particularly difficult. As widely reported in the literature, the outcome of myocardial infarction in women is poorer than in their male counterparts for a number of reasons. We can assume that in the youngest patients, another physiopathological mechanism is often involved, namely, the occurrence of hematoma and spontaneous coronary dissection. Diagnosis is often difficult even with coronary angiography diagnosis. As shown in the case reported here, initial examination results, if not thoroughly analyzed, may be erroneously interpreted as normal. It is also likely that the presence of hematoma or coronary wall dissection without any plaque rupture may negatively influence the outcome owing to the implementation of inappropriate treatments. In conclusion, in patients presenting with an ischemic cerebral accident, meticulous cardiac examination must be performed even in young women with no cardiovascular risk factors given that the occurrence of hematoma or coronary dissection may contribute to the formation of mural thrombi in the setting of myocardial infarction. Cardiac MRI seems to be particularly effective in the diagnosis of myocardial infarction

  15. Sleep in spontaneous dwarf rats.

    Science.gov (United States)

    Peterfi, Zoltan; Obal, Ferenc; Taishi, Ping; Gardi, Janos; Kacsoh, Balint; Unterman, Terry; Krueger, James M

    2006-09-07

    Spontaneous dwarf rats (SDRs) display growth hormone (GH) deficiency due to a mutation in the GH gene. This study investigated sleep in SDRs and their somatotropic axis and compared to Sprague-Dawley rats. SDRs had almost undetectable levels of plasma GH. Hypothalamic GH-releasing hormone (GHRH) mRNA was increased, whereas GHRH-receptor (GHRH-R) and somatostatin mRNAs were decreased in SDRs. Hypothalamic GHRH and somatostatin peptide content decreased in SDRs. Quantitative immunohistochemistry for GHRH and GHRH-R corroborated and extended these findings. In the arcuate nucleus, the number of GHRH-positive cells was significantly higher, whereas GHRH-R-positive perikarya were diminished in SDRs. Cortical GHRH and GHRH-R measurements showed similar expression characteristics as those found in the hypothalamus. SDRs had less rapid eye movement sleep (REMS) and more non-REMS (NREMS) than the control rats during the light period. The electroencephalogram (EEG) delta and theta power decreased during NREMS in the SDRs. After 4-h of sleep deprivation, SDRs had a significantly reduced REMS rebound compared to the controls, whereas NREMS rebound was normal in SDRs. The enhancement in delta power was significantly less than in the control group during recovery sleep. Intracerebroventricular (icv) administration of GHRH promoted NREMS in both strains of rats; however, increased REMS and EEG delta activity was observed only in control rats. Icv injection of insulin-like growth factor 1 increased NREMS in control rats, but not in the SDRs. These results support the ideas that GHRH is involved in NREMS regulation and that GH is involved in the regulation of REMS and in EEG slow wave activity regulation during NREMS.

  16. Spontaneous Toroidal Rotation in Tokamaks

    Science.gov (United States)

    Haines, Malcolm

    2007-11-01

    When two-fluid MHD theory of stability is employed the resulting growth rates are complex, and the perturbing magnetic fields move with a velocity that depends both on the components of the electron drift and heat flux perpendicular to the equilibrium magnetic field and on the diamagnetic velocity. On diffusing into a resistive wall a drag force is exerted on the wall which is proportional to the square-root of the velocity of the perturbing fields. The equal and opposite force or torque will be on the plasma, centred at the singular rational surface for each mode[1]. For typical experimental conditions this leads to a spontaneous, or intrinsic toroidal rotation of 20km/s occurring in a few milliseconds for perturbing magnetic fields of 0.0025tesla. The induced poloidal rotation by this mechanism is generally much larger, but there is considerable poloidal damping due to trapped particles on the ion-ion collision time- scale[2]. Furthermore poloidal angular momentum is in general not conserved for an isolated plasma, and any up-down asymmetry can act as a source or sink[3]; for example, Pfirsch-Schluter diffusion [3 damping by trapped particles[2] and the Ware pinch[4]. [1] J.B.Taylor, Phys.Rev.Lett. 91, 115002 (2003). [2] R.C.Morris, M.G.Haines and R.J.Hastie, Phys.Plasmas 3, 4513 (1996). [3] M.G.Haines, Phys.Rev.Lett. 25, 1480 (1970). [4] M.G.Haines and P.Martin, Phys.Plasmas 3, 4536 (1996).

  17. Mixed heterotopic gastrointestinal cyst and extranasal glial tissue of ...

    African Journals Online (AJOL)

    We report an unusual case of mixed choristoma in posterior tongue and left submandibular region in a 6-month-old male baby who had cleft palate. The patient presented with spontaneous bleeding from mouth and recurrent swelling in submandibular region. The histology of the surgical resected specimens displayed ...

  18. Lunar Cycle Influences Spontaneous Delivery in Cows.

    Science.gov (United States)

    Yonezawa, Tomohiro; Uchida, Mona; Tomioka, Michiko; Matsuki, Naoaki

    2016-01-01

    There is a popular belief that the lunar cycle influences spontaneous delivery in both humans and cattle. To assess this relationship, we investigated the synodic distribution of spontaneous deliveries in domestic Holstein cows. We used retrospective data from 428 spontaneous, full-term deliveries within a three-year period derived from the calving records of a private farm in Hokkaido, Japan. Spontaneous birth frequency increased uniformly from the new moon to the full moon phase and decreased until the waning crescent phase. There was a statistically significant peak between the waxing gibbous and full moon phases compared with those between the last quarter and the waning crescent. These changes were clearly observed in deliveries among multiparous cows, whereas they were not evident in deliveries among nulliparous cows. These data suggest the utility of dairy cows as models for bio-meteorological studies, and indicate that monitoring lunar phases may facilitate comprehensive understanding of parturition.

  19. Spontaneous Trait Inferences on Social Media.

    Science.gov (United States)

    Levordashka, Ana; Utz, Sonja

    2017-01-01

    The present research investigates whether spontaneous trait inferences occur under conditions characteristic of social media and networking sites: nonextreme, ostensibly self-generated content, simultaneous presentation of multiple cues, and self-paced browsing. We used an established measure of trait inferences (false recognition paradigm) and a direct assessment of impressions. Without being asked to do so, participants spontaneously formed impressions of people whose status updates they saw. Our results suggest that trait inferences occurred from nonextreme self-generated content, which is commonly found in social media updates (Experiment 1) and when nine status updates from different people were presented in parallel (Experiment 2). Although inferences did occur during free browsing, the results suggest that participants did not necessarily associate the traits with the corresponding status update authors (Experiment 3). Overall, the findings suggest that spontaneous trait inferences occur on social media. We discuss implications for online communication and research on spontaneous trait inferences.

  20. Rapid and spontaneous recovery in autistic disorder

    OpenAIRE

    Sitholey, Prabhat; Agarwal, Vivek; Pargaonkar, Amol

    2009-01-01

    Recovery in autistic disorder is rare. There are few reports of recovery from autistic disorder after a few years of therapeutic intervention. We report here a case of autistic disorder who recovered spontaneously without any intervention in 13 days.

  1. Right Diaphragm Spontaneous Rupture: A Surgical Approach

    Directory of Open Access Journals (Sweden)

    Duilio Divisi

    2011-01-01

    Full Text Available We present a case of spontaneous rupture of the diaphragm, characterized by nonspecific symptoms. The rapid diagnosis and appropriate surgical approach led to a positive resolution of the pathology.

  2. Recurrent spontaneous pneumoperitoneum: A surgical dilemma

    Directory of Open Access Journals (Sweden)

    Polly Estridge

    2017-01-01

    Conclusion: A trial of conservative management may be appropriate in patients with spontaneous pneumoperitoneum but it must always be borne in mind that clinical deterioration represents an indication for surgical intervention.

  3. Spontaneous coronary artery dissection during cabergoline therapy.

    Science.gov (United States)

    Mehta, Nishaki Kiran; Malkani, Samir; Ockene, Ira

    2012-01-01

    Although spontaneous coronary artery dissection is a rare cause of acute coronary syndrome, it should be considered during the evaluation of patients who have chest pain. Coronary vasospasm can lead to spontaneous dissection. The dopamine agonist cabergoline is known to cause digital vasospasm. Herein, we report a case of spontaneous right coronary artery dissection in a 43-year-old woman who was taking cabergoline as therapy for prolactinoma. To our knowledge, this is the first report of an apparent relationship between cabergoline therapy and spontaneous coronary artery dissection. The possible association of cabergoline with coronary artery spasm and dissection should be considered in patients who present with chest pain while taking this medication.

  4. Quantum wave mixing and visualisation of coherent and superposed photonic states in a waveguide.

    Science.gov (United States)

    Dmitriev, A Yu; Shaikhaidarov, R; Antonov, V N; Hönigl-Decrinis, T; Astafiev, O V

    2017-11-07

    Superconducting quantum systems (artificial atoms) have been recently successfully used to demonstrate on-chip effects of quantum optics with single atoms in the microwave range. In particular, a well-known effect of four wave mixing could reveal a series of features beyond classical physics, when a non-linear medium is scaled down to a single quantum scatterer. Here we demonstrate the phenomenon of quantum wave mixing (QWM) on a single superconducting artificial atom. In the QWM, the spectrum of elastically scattered radiation is a direct map of the interacting superposed and coherent photonic states. Moreover, the artificial atom visualises photon-state statistics, distinguishing coherent, one- and two-photon superposed states with the finite (quantised) number of peaks in the quantum regime. Our results may give a new insight into nonlinear quantum effects in microwave optics with artificial atoms.

  5. Depressive disorder and grief following spontaneous abortion.

    Science.gov (United States)

    Kulathilaka, Susil; Hanwella, Raveen; de Silva, Varuni A

    2016-04-12

    Abortion is associated with moderate to high risk of psychological problems such as depression, use of alcohol or marijuana, anxiety, depression and suicidal behaviours. The increased risk of depression after spontaneous abortion in Asian populations has not been clearly established. Only a few studies have explored the relationship between grief and depression after abortion. A study was conducted to assess the prevalence and risk factors of depressive disorder and complicated grief among women 6-10 weeks after spontaneous abortion and compare the risk of depression with pregnant women attending an antenatal clinic. Spontaneous abortion group consisted of women diagnosed with spontaneous abortion by a Consultant Obstetrician. Women with confirmed or suspected induced abortion were excluded. The comparison group consisted of randomly selected pregnant, females attending the antenatal clinics of the two hospitals. Diagnosis of depressive disorder was made according to ICD-10 clinical criteria based on a structured clinical interview. This assessment was conducted in both groups. The severity of depressive symptoms were assessed using the Patients Health Questionnaire (PHQ-9). Grief was assessed using the Perinatal Grief Scale which was administered to the women who had experienced spontaneous abortion. The sample consisted of 137 women in each group. The spontaneous abortion group (mean age 30.39 years (SD = 6.38) were significantly older than the comparison group (mean age 28.79 years (SD = 6.26)). There were more females with ≥10 years of education in the spontaneous abortion group (n = 54; SD = 39.4) compared to the comparison group (n = 37; SD = 27.0). The prevalence of depression in the spontaneous abortion group was 18.6 % (95 CI, 11.51-25.77). The prevalence of depression in the comparison group was 9.5 % (95 CI, 4.52-14.46). Of the 64 women fulfilling criteria for grief, 17 (26.6 %) also fulfilled criteria for a depressive episode. The relative risk of

  6. Assessment of Relationship between Spontaneous Abortion and Occupational Exposure to Organic Solvents

    Directory of Open Access Journals (Sweden)

    S Mohammadi

    2011-04-01

    Full Text Available Introduction & Objective: Nowadays, some studies indicate the adverse effects of exposure to chemicals, especially organic solvents on the reproductive system of females. This study aimed to assess the relationship between spontaneous abortion with occupational exposure to organic solvents in pharmaceutical industry. Materials & Methods: This is a cross-sectional and descriptive-analytical study which was carried out in 2010 in one of the pharmaceutical factories located in the suburbs of Tehran. During the study, married women who were working in the factory laboratory units and were exposed to mixed organic solvents were compared with married women who were working in the packing units of the factory without occupational exposure to organic solvents. Frequency of spontaneous abortion and duration of pregnancy were assessed in both two groups. Collected data were analyzed with the SPSS software using t-test, logistic regression, and chi-square test. Results: In the present study, the frequency of spontaneous abortion in employees with exposure to organic solvents mixture was 10.7%. This study showed that even after adjustment for confounding factors, there was a significant correlation between spontaneous abortion and occupational exposure to organic solvents mixture and this correlation increased with increasing levels of exposure to organic solvents. Moreover, a significant correlation was observed between occupational exposure to mixed organic solvents and waiting time to become pregnant (TTP. Furthermore, this study showed that even after adjustment for confounding variables, shift workers were significantly more affected by spontaneous abortion compared to daytime workers (P < 0.001. Conclusion: According to the results of this study, since there is probability of spontaneous abortion resulting from occupational exposure to various chemicals including organic solvents, review of the status of occupational exposure of workers can be helpful

  7. Spontaneous regression of metastatic Merkel cell carcinoma.

    LENUS (Irish Health Repository)

    Hassan, S J

    2010-01-01

    Merkel cell carcinoma is a rare aggressive neuroendocrine carcinoma of the skin predominantly affecting elderly Caucasians. It has a high rate of local recurrence and regional lymph node metastases. It is associated with a poor prognosis. Complete spontaneous regression of Merkel cell carcinoma has been reported but is a poorly understood phenomenon. Here we present a case of complete spontaneous regression of metastatic Merkel cell carcinoma demonstrating a markedly different pattern of events from those previously published.

  8. Spontaneous Trait Inferences on Social Media

    OpenAIRE

    Levordashka, Ana; Utz, Sonja

    2016-01-01

    The present research investigates whether spontaneous trait inferences occur under conditions characteristic of social media and networking sites: nonextreme, ostensibly self-generated content, simultaneous presentation of multiple cues, and self-paced browsing. We used an established measure of trait inferences (false recognition paradigm) and a direct assessment of impressions. Without being asked to do so, participants spontaneously formed impressions of people whose status updates they sa...

  9. Spontaneous intracranial epidural hematoma during rivaroxaban treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ruschel, Leonardo Gilmone; Rego, Felipe Marques Monteiro do; Milano, Jeronimo Buzetti; Jung, Gustavo Simiano; Silva Junior, Luis Fernando; Ramina, Ricardo, E-mail: leonardoruschel@yahoo.com.br [Instituto de Neurologia de Curitiba (INC), Curitiba, PR (Brazil)

    2016-11-15

    According to our research, this is the first case described in the literature of spontaneous intracranial epidural hematoma secondary to the use of Xarelto®. Spontaneous intracranial epidural hematomas are rarely described in the literature. They are associated with infectious diseases of the skull, coagulation disorders, vascular malformations of the dura mater and metastasis to the skull. Long-term post-marketing monitoring and independent reports will probably detect the full spectrum of hemorrhagic complications of the use of rivaroxaban. (author)

  10. Spontaneous mirror symmetry breaking via enantioselective autocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Avetisov, V.A. [N. N. Semenov Institute of Chemical Physics of the Russian Academy of Sciences, ul.Kossvgina 4, 11-7977 Moscow (Russia)

    1996-07-01

    The conditions for spontaneous generation of optically active product under autocatalytic type reactions is considered on the base of the general kinetic model of enantioselective autocatalytic stages. It is shown that the spontaneous generation of optical activity mostly depends on the enantioselectivity of catalytic transformations. The properties of autocatalytic reactions, which are needed for an experiment, as well as the necessary chemical conditions, are discussed. {copyright} {ital 1996 American Institute of Physics.}

  11. Symptomatic tarlov cyst following spontaneous subarachnoid hemorrhage.

    Science.gov (United States)

    Kong, Woo Keun; Cho, Keun-Tae; Hong, Seung-Koan

    2011-08-01

    Most of Tarlov or perineurial cysts remain asymptomatic throughout the patient's life. The pathogenesis is still unclear. Hemorrhage has been suggested as one of the possible causes and trauma with resultant hemorrhage into subarachnoid space has been suggested as an origin of these cysts. However, Tarlov cysts related to spontaneous subarachnoid hemorrhage has not been reported. The authors report a case of Tarlov cyst which was symptomatic following spontaneous subarachnoid hemorrhage.

  12. Symptomatic Tarlov Cyst Following Spontaneous Subarachnoid Hemorrhage

    OpenAIRE

    Kong, Woo Keun; Cho, Keun-Tae; Hong, Seung-Koan

    2011-01-01

    Most of Tarlov or perineurial cysts remain asymptomatic throughout the patient's life. The pathogenesis is still unclear. Hemorrhage has been suggested as one of the possible causes and trauma with resultant hemorrhage into subarachnoid space has been suggested as an origin of these cysts. However, Tarlov cysts related to spontaneous subarachnoid hemorrhage has not been reported. The authors report a case of Tarlov cyst which was symptomatic following spontaneous subarachnoid hemorrhage.

  13. Spontaneous lung herniation after a single cough

    Energy Technology Data Exchange (ETDEWEB)

    Tack, D.; Delcour, C. [Dept. of Radiology, C. H. U. de Charleroi (Belgium); Wattiez, A. [Dept. of Pneumology, C. H. U. de Charleroi (Belgium); Schtickzelle, J.C. [Dept. of Emergency Medicine, C. H. U. de Charleroi (Belgium)

    2000-03-01

    Herniation of the lung is commonly caused by congenital rib abnormalities, blunt trauma, or thoracic surgery. Spontaneous hernias are rarely described in the literature. We report a case of a spontaneous intercostal pulmonary hernia following a single cough. In addition, a review of the literature is presented which outlines the classification, causes, and incidence of lung hernias. Some reference is made to possible methods of treatment. (orig.)

  14. Characteristics of patients with spontaneous splenic rupture.

    Science.gov (United States)

    Kocael, Pinar Cigdem; Simsek, Osman; Bilgin, Ismail Ahmet; Tutar, Onur; Saribeyoglu, Kaya; Pekmezci, Salih; Goksoy, Ertugrul

    2014-01-01

    In the present study, we aim to share our clinical experience in patients with spontaneous splenic rupture. Splenic rupture without trauma is known as spontaneous splenic rupture. The major problems in the management of spontaneous splenic rupture are missed or delayed diagnosis due to the lack of trauma in most cases. The records of all patients, who were admitted to Cerrahpaşa Medical Faculty, Istanbul University, were retrospectively reviewed from January 2000 to March 2013. Twelve patients were admitted to the emergency department and they were diagnosed with spontaneous splenic rupture. The mean age was 47.6 years. All patients had complaints of abdominal pain. The mean hematocrit value was 22%. Radiologic assessment revealed hemoperitoneum and/or subcapsular hematoma in 8 patients while splenic abscess was diagnosed in 2 patients. Eleven patients underwent splenectomy whereas one was managed conservatively. The most common cause of spontaneous splenic rupture was determined to be use of anticoagulants. Etiology was considered to be idiopathic in 1 patient. Two patients died in the postoperative period. Although rare, spontaneous splenic rupture must be suspected in emergency patients who have used especially anticoagulants and antiaggregants and who have had no recent history of trauma. One of the important causes of mortality is missed or delayed diagnosis.

  15. FEL gain optimisation and spontaneous radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bali, L.M.; Srivastava, A.; Pandya, T.P. [Lucknow Univ. (India)] [and others

    1995-12-31

    Colson have evaluated FEL gains for small deviations from perfect electron beam injection, with radiation of the same polarisation as that of the wiggler fields. We find that for optimum gain the polarisation of the optical field should be the same as that of the spontaneous emission under these conditions. With a helical wiggler the axial oscillations resulting from small departures from perfect electron beam injection lead to injection dependent unequal amplitudes and phases of the spontaneous radiation in the two transverse directions. Viewed along the axis therefore the spontaneous emission is elliptically polarised. The azimuth of the ellipse varies with the difference of phase of the two transverse components of spontaneous emission but the eccentricity remains the same. With planar wigglers the spontaneous emission viewed in the axial direction is linearly polarised, again with an injection dependent azimuth. For optimum coherent gain of a radiation field its polarisation characteristics must be the same as those of the spontaneous radiation with both types of wiggler. Thus, with a helical wiggler and the data reported earlier, an increase of 10% in the FEL gain at the fundamental frequency and of 11% at the fifth harmonic has been calculated in the small gain per pass limit. Larger enhancements in gain may result from more favourable values of input parameters.

  16. Frequencies of spontaneous breast development and spontaneous menarche in Turner syndrome in Japan

    Science.gov (United States)

    Tanaka, Toshiaki; Igarashi, Yutaka; Ozono, Keiichi; Ohyama, Kenji; Ogawa, Masamichi; Osada, Hisao; Onigata, Kazumichi; Kanzaki, Susumu; Kohno, Hitoshi; Seino, Yoshiki; Takahashi, Hiroaki; Tajima, Toshihiro; Tachibana, Katsuhiko; Tanaka, Hiroyuki; Nishi, Yoshikazu; Hasegawa, Tomonobu; Fujita, Keinosuke; Yorifuji, Tohru; Horikawa, Reiko; Yokoya, Susumu

    2015-01-01

    Abstract. The Growject® database on human GH treatment in Turner syndrome was analyzed in the Turner Syndrome Research Collaboration, and the relationships of the frequencies of spontaneous breast development and spontaneous menarche with karyotype and GH treatment were investigated. One hundred and three cases started GH treatment with 0.5 IU/kg/ week (0.5 IU group), and their dose was increased to 0.35 mg/kg/wk midway through the treatment course. Another 109 cases started GH at a dose of 0.35 mg/kg/wk (0.35 mg group). Spontaneous breast development was observed in 77 (36.3%) of the 212 patients, and spontaneous menarche occurred in 31 patients (14.6%). The frequency of spontaneous breast development was significantly lower in patients with the 45,X karyotype and significantly higher in patients with a structural abnormality of the second X chromosome. The frequency of spontaneous menarche was significantly higher in patients with mosaicism characterized by X monosomy and a cellular line with no structural abnormality of the X chromosome. No significant differences in frequencies of spontaneous breast development and spontaneous menarche were observed between the two dose groups, indicating that GH treatment does not increase the frequency of spontaneous puberty. PMID:26568657

  17. Dynamics of spontaneous otoacoustic emissions

    Science.gov (United States)

    Bergevin, Christopher; Salerno, Anthony

    2015-12-01

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

  18. Immunohistochemical characterization of spontaneous and acrylonitrile-induced brain tumors in the rat.

    Science.gov (United States)

    Kolenda-Roberts, Holly Meredith; Harris, Nancy; Singletary, Emily; Hardisty, Jerry F

    2013-01-01

    Twenty-eight spontaneously occurring glial tumors (previously diagnosed as astrocytomas, oligodendrogliomas, and gliomas) and eleven granular cell tumors (GCTs) were selected for evaluation using a panel of immunohistochemistry (IHC) stains (Ricinus communis agglutinin type 1 [RCA-1], ionized calcium-binding adapter molecule 1 [Iba-1], OX-6/major immunohistocompatibility complex class II, oligodendrocytes transcription factor 2 [Olig2], glial fibrillary acidic protein [GFAP], S100 beta, glutamine synthetase, neurofilament, proliferating cell nuclear antigen). In addition, nine brain tumors from a 2-year drinking water study for acrylonitrile were obtained from the Acrylonitrile Group, Inc. Based on IHC staining characteristics, Olig2+ oligodendrogliomas were the most commonly diagnosed spontaneous tumor in these animals. Many of the spontaneous tumors previously diagnosed as astrocytomas were RCA-1+, Iba-1+ and negative for GFAP, S100beta, and glutamine synthetase; the diagnosis of malignant microglial tumor is proposed for these neoplasms. Three mixed tumors were identified with Olig2+ (oligodendrocytes) and Iba-1+ (macrophage/microglia) cell populations. The term mixed glioma is not recommended for these tumors, as it is generally used to refer to oligoastrocytomas, which were not observed in this study. GCT were positive for RCA-1 and Iba-1. All acrylonitrile tumors were identified as malignant microglial tumors. These results may indicate that oligodendrogliomas are more common as spontaneous tumors, while acrylonitrile-induced neoplasms are microglial/histiocytic in origin. No astrocytomas (GFAP, S100 beta, and/or glutamine synthetase-positive neoplasms) were observed.

  19. Spontaneous closure of muscular ventricular septal defects

    Directory of Open Access Journals (Sweden)

    Pejčić Ljiljana

    2017-01-01

    Full Text Available Introduction/Objective. Ventricular septal defect (VSD is the most frequently diagnosed congenital heart anomaly. The prognosis is usually good as it has spontaneous closure evolution, especially small muscular VSDs. The aim of this study was to determine the natural history of isolated muscular VSDs including the frequency of spontaneous closure in relation to location in the muscular septum and the age at the time of closure. Methods. The study included 96 children (52 girls and 44 boys with isolated muscular VSD diagnosed during the first month of life. We analyzed the tendency of spontaneous closure of these defects for the duration of childhood during a follow-up period of 16 years. Two-dimensional color Doppler echocardiography was performed to detect muscular VSD as a primary cardiac lesion. There was significant prevalence of small apical versus trabecular defects and their outcomes were evaluated. Results. Our study evaluated 91 children, 49 (53.8% girls and 42 (46.2% boys who did not undergo surgery. Apically located VSD was diagnosed in 68 (74.7%, while trabecular defects were found in 23 (25.3% children. Spontaneous closure occurred in 56 out of 91 cases (61.5%. The time of spontaneous closure was most commonly recorded during the first six months after birth (46.4%. The overall rate of spontaneous closure was 81.3% by the end of the first year. Apically located ventricular defects underwent spontaneous closure in the majority of patients, in comparison to trabecular ventricular defects (χ2 = 12.581; p < 0.001. Kaplan–Meier analysis demonstrated a significant difference in the average time required for spontaneous closure between the analyzed patient groups (log-rank = 9.64, p = 0.002. Conclusion. The frequency of spontaneous closure of muscular VSDs, especially apically located, is very high in the first six months, especially within the first year of life. It is advisable to detect them early on using color flow imaging and to

  20. Mixed plastics recycling technology

    CERN Document Server

    Hegberg, Bruce

    1995-01-01

    Presents an overview of mixed plastics recycling technology. In addition, it characterizes mixed plastics wastes and describes collection methods, costs, and markets for reprocessed plastics products.

  1. The spontaneous generation of magnetic fields at high temperature in a supersymmetric theory

    OpenAIRE

    Demchik, V. I.; Skalozub, V. V.

    2002-01-01

    The spontaneous generation of magnetic and chromomagnetic fields at high temperature in the minimal supersymmetric standard model (MSSM) is investigated. The consistent effective potential including the one-loop and the daisy diagrams of all bosons and fermions is calculated and the magnetization of the vacuum is observed. The mixing of the generated fields due to the quark and s-quark loop diagrams and the role of superpartners are studied in detail. It is found that the contribution of thes...

  2. Spontaneous abortion and maternal work in greenhouses.

    Science.gov (United States)

    Settimi, Laura; Spinelli, Angela; Lauria, Laura; Miceli, Giuseppe; Pupp, Nicoletta; Angotzi, Giuliano; Fedi, Aldo; Donati, Serena; Miligi, Lucia; Osborn, John; Figà-Talamanca, Irene

    2008-04-01

    A positive association between maternal occupational exposure to pesticide and spontaneous abortion has been reported in some studies. Work in greenhouses may imply exposure of pregnant women to pesticides continuously and at elevated level. A total of 717 women working in greenhouses provided information on 973 pregnancies, including 110 spontaneous abortions. These pregnancies were classified as exposed or not exposed according to maternal occupation, re-entry activities and application of pesticides in greenhouses during at least 1 month in the first trimester of pregnancy. The ORs for spontaneous abortion were estimated through a generalised estimate equations model for all orders of pregnancy together, and through a logistic regression model limited to first pregnancies. Increased risks of spontaneous abortion were found for maternal re-entry activities within 24 hr after pesticides were applied (all orders of pregnancy: OR 3.2, 95% CI 1.3-7.7; first pregnancies: OR 3.8, 95% CI 1.0-13.9) and for those who applied pesticides (all orders of pregnancy: OR 2.6, 95% CI 1.0-6.6; first pregnancies: OR 3.7, 95% CI 0.7-20,6) The observed results support the hypothesis of an association between maternal work in greenhouses and spontaneous abortion. The main limitations of the study are lack of information on the specific chemicals used and the small number of pregnancies heavily exposed to pesticides. (c) 2008 Wiley-Liss, Inc.

  3. Methodology in Aristotle's Theory of Spontaneous Generation.

    Science.gov (United States)

    Zwier, Karen R

    2017-10-10

    Aristotle's theory of spontaneous generation offers many puzzles to those who wish to understand his theory both within the context of his biology and within the context of his more general philosophy of nature. In this paper, I approach the difficult and vague elements of Aristotle's account of spontaneous generation not as weaknesses, but as opportunities for an interesting glimpse into the thought of an early scientist struggling to reconcile evidence and theory. The paper has two goals: (1) to give as charitable and full an account as possible of what Aristotle's theory of spontaneous generation was, and to examine some of its consequences; and (2) to reflect on Aristotle as a scientist, and what his comments reveal about how he approached a difficult problem. In particular, I propose that the well-recognized problem of the incompatibility between Aristotle's concept of spontaneity and his theory of spontaneous generation presents an opportunity for insight into his scientific methodology when approaching ill-understood phenomena.

  4. Spontaneous body movements in spatial cognition

    Directory of Open Access Journals (Sweden)

    Sergiu eTcaci Popescu

    2012-05-01

    Full Text Available People often perform spontaneous body movements during spatial tasks such as giving complex directions or orienting themselves on maps. How are these spontaneous gestures related to spatial problem-solving? We measured spontaneous movements during a perspective-taking task inspired by map reading. Analyzing the motion data to isolate rotation and translation components of motion in specific geometric relation to the task, we found out that most participants executed spontaneous miniature rotations of the head that were significantly related to the main task parameter. These head rotations were as if participants were trying to align themselves with the orientation on the map either in the image plane or on the ground plane, but with tiny amplitudes, typically below 1% of the actual movements. Our results are consistent with a model of sensorimotor prediction driving spatial reasoning. The efference copy of planned movements triggers this prediction mechanism. The movements themselves may then be mostly inhibited; the small spontaneous gestures that we measure are the visible traces of these planned but inhibited actions.

  5. Spontaneous intracranial hypotension: diagnosis to management.

    Science.gov (United States)

    Limaye, Kaustubh; Samant, Rohan; Lee, Ricky W

    2016-06-01

    Spontaneous Intracranial Hypotension typically occurs from spontaneous CSF leak. CSF volume depletion rather than decrease in CSF pressure is thought to be the main causative feature for intracranial hypotension. More and more cases of intracranial hypotension are getting diagnosed with the advances in the imaging. The advances in the imaging have also led to the better understanding of the dynamic changes that occur with intracranial hypotension. The old theories of CSF overproduction or CSF underproduction have not been substantially associated with intracranial hypotension. It has also led to the fore different atypical clinical features and presentations. Although, it has been known for a long time, the diagnosis is still challenging and dilemma persists over one diagnostic modality over other and the subsequent management. Spontaneous CSF leaks occur at the spinal level and the skull base and other locations are rare. The anatomy of spontaneous intracranial hypotension is a very complex process with significant overlap in connective tissue disorders, previous dural weakness or meningeal diverticula. To localize the location of the CSF leak-CT myelography is the modality of choice. CSF cysternography may provide additional confirmation in uncertain cases and also MRI spine imaging may be of significant help in some cases. Spontaneous intracranial hypotension continues to be a diagnostic dilemma and our effort was to consolidate available information on the clinical features, diagnostics, and management for a practicing neurologist for a "15-20 min quick update of the topic".

  6. Model for the spontaneous heating of coal

    Energy Technology Data Exchange (ETDEWEB)

    Schmal, D.; Duyzer, J.H.; Heuven, J.W. van

    1985-07-01

    As part of an investigation into the spontaneous heating of coal piles, a one-dimensional model has been developed to describe the spontaneous heating process at relatively low temperatures (less than about 100 C). The ultimate unsteady-state model takes into account depletion of oxygen and production of heat by chemisorption of oxygen in the coal, transport of oxygen by diffusion and convection and transport of heat by conduction, convection and evaporation/condensation of coal moisture. It consists of four differential equations, for conservation of oxygen mass, of coal moisture and of heat and rate of reaction of oxygen with coal. Calculations using data from laboratory and field experiments give results that describe the process of spontaneous heating semiquantitatively. The most important parameters in the process of spontaneous heating, particularly for the time between stacking and spontaneous ignition, are the porosity of the pile (degree of compaction), the initial temperature of the coal and the evaporation and condensation of coal moisture. The influence of other parameters (e.g. reactivity of the coal, thermal conductivity) is much less pronounced. 12 references.

  7. Spontaneous Regression of Lumbar Herniated Disc

    Directory of Open Access Journals (Sweden)

    Chun-Wei Chang

    2009-12-01

    Full Text Available Intervertebral disc herniation of the lumbar spine is a common disease presenting with low back pain and involving nerve root radiculopathy. Some neurological symptoms in the majority of patients frequently improve after a period of conservative treatment. This has been regarded as the result of a decrease of pressure exerted from the herniated disc on neighboring neurostructures and a gradual regression of inflammation. Recently, with advances in magnetic resonance imaging, many reports have demonstrated that the herniated disc has the potential for spontaneous regression. Regression coincided with the improvement of associated symptoms. However, the exact regression mechanism remains unclear. Here, we present 2 cases of lumbar intervertebral disc herniation with spontaneous regression. We review the literature and discuss the possible mechanisms, the precipitating factors of spontaneous disc regression and the proper timing of surgical intervention.

  8. Spontaneous hemothorax: primary pleural epithelioid angiosarcoma

    Directory of Open Access Journals (Sweden)

    Amit Panjwani

    2016-01-01

    Full Text Available Spontaneous hemothorax is a rare condition seen in coagulation and vascular disorders. Uncommonly, malignant neoplasms may cause spontaneous hemothorax. Primary pleural epithelioid angiosarcomas (excluding the cases with pleuropulmonary or chest wall involvement are extremely rare pleural tumors, which may be mistaken for mesothelioma or adenocarcinoma, and only 19 cases (one of them from India have been reported in the English literature, to date. It commonly occurs in older men, has a nonspecific clinicoradiological presentation, and carries a poor prognosis with no survivors beyond a year of establishing the diagnosis. We report a case of primary pleural epithelioid angiosarcoma presenting as a life-threatening spontaneous hemothorax. We also present a brief literature review on pleural angiosarcoma.

  9. Spontaneous Perforation of Pyometra: A Case Report

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Pyometra is the accumulation of purulent material in the uterine cavity. Its reported incidence is 0.01–0.5% in gynecologic patients; however, as far as elderly patients are concerned, its incidence is 13.6% [3]. The most common cause of pyometra is malignant diseases of genital tract and the consequences of their treatment (radiotherapy. Other causes are benign tumors like leiomyoma, endometrial polyps, senile cervicitis, cervical occlusion after surgery, puerperal infections, and congenital cervical anomalies. Spontaneous rupture of the uterus is an extremely rare complication of pyometra. To our knowledge, only 21 cases of spontaneous perforation of pyometra have been reported in English literature since 1980. This paper reports an additional case of spontaneous uterine rupture.

  10. Creating a Spontaneous Conversational Speech Corpus

    Directory of Open Access Journals (Sweden)

    Maria Husin

    2011-11-01

    Full Text Available Speech recognition and language analysis of spontaneous speech arising in naturally spoken conversations are becoming the subject of much research. However, there is a shortage of spontaneous speech corpora that are freely available for academics. We therefore undertook the building of a natural conversation speech database, recording over 200 hours of conversations in English by over 600 local university students. With few exceptions, the students used their own cell phones from their own rooms or homes to speak to one another, and they were permitted to speak on any topic they chose. Although they knew that they were being recorded and that they would receive a small payment, their conversations in the corpus are probably very close to being natural and spontaneous. This paper describes a detailed case study of the problems we faced and the methods we used to make the recordings and control the collection of these social science data on a limited budget.

  11. Ultrafast spontaneous emission source using plasmonic nanoantennas

    Science.gov (United States)

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

    2015-07-01

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

  12. Spontaneous loosening of hydroxyapatite peg sleeves.

    Science.gov (United States)

    Jordan, D R

    2001-11-01

    To report a new complication associated with pegging hydroxyapatite orbital implants: spontaneous loosening of the sleeve. Retrospective noncomparative case series. Four patients ranging in age from 38 to 60 years participated. Four patients are described who successfully received hydroxyapatite orbital implants with motility peg and sleeve systems. In each case spontaneous loosening of the sleeve developed. Clinical and surgical outcomes were assessed. Three patients had the peg and sleeve removed followed by repair of the peg hole, and one patient had placement of a larger diameter peg and sleeve system. All patients did well. Problems have been reported when motility coupling pegs are used with hydroxyapatite orbital implants. Spontaneous loosening of the sleeve is another potential complication to discuss with the patient considering an implant peg.

  13. Approach to the patient with spontaneous hypoglycemia.

    Science.gov (United States)

    Martens, Pieter; Tits, Jos

    2014-06-01

    Hypoglycemia is common in daily clinical practice and often occurs during the treatment of diabetes mellitus. However, a small minority of hypoglycemia encountered in clinical practice is spontaneous and thus not induced by glycemic lowering agents. These spontaneous hypoglycemic events confront the clinician with a diagnostic enigma. Although the trained clinician can recognize the autonomic and neuroglycopenic symptoms of hypoglycemia even in a patient not on insulin, it remains challenging to decipher the etiology of a spontaneous hypoglycemic event. A logical and stepwise approach to the spontaneous hypoglycemic event allows for a conclusive diagnosis. This diagnostic process consists of adequately diagnosing hypoglycemia by fulfilling Whipple's triad, stratifying patients according to their clinical status and analyzing a full hypoglycemic blood panel. A complete hypoglycemic blood panel should include the analysis of glucose, insulin, C-peptide, pro-insulin, insulin antibodies and the presence of oral hypoglycemic agents. For patients with episodes of hypoglycemia induced by excessive endogenous insulin, additional imaging is often required to detect the presence of an underlying insulinoma. By diagnosing the underlying cause of the spontaneous hypoglycemia, the physician also diagnosis the mechanism by which the hypoglycemic event occurs. Allowing for a problem orientated therapeutic approach. The present review is based upon a comprehensive PubMed search between 1985 and 2013. This uses search terms of spontaneous hypoglycemia, insulinoma, nesidioblastosis, insulin auto-immunity, noninsulinoma pancreatogenous hypoglycemia syndrome, hormone deficiency, pro-IGF II, and pro-insulin growth factor II, and cross reference searching of pivotal articles in the subject. Copyright © 2014 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  14. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

    Hjollund, N H; Jensen, T K; Bonde, J P

    2000-01-01

    Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short...... pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date...

  15. Spontaneous conversion of first onset atrial fibrillation

    DEFF Research Database (Denmark)

    Lindberg, Søren Østergaard; Hansen, Sidsel; Nielsen, Tonny

    2011-01-01

    consecutive patients admitted to hospital with first onset AF from January 1, 2006, to December 31, 2009. The patients were divided into two groups, recent onset AF defined as AF defined as AF > 48 hours. Spontaneous conversion occurred in 54%, (n = 203; 95% CI: 49 - 59......%). In the group with first onset AF 48 hours. Logistic regression analysis identified duration of AF as a highly significant predictor of spontaneous conversion to sinus rhythm (OR 5.9; 95% CI; 4.0 - 8.6, P

  16. Spontaneous Bilateral Meningoencephalocoeles of the Temporal Bones

    Directory of Open Access Journals (Sweden)

    Oliver Rose

    2013-01-01

    Full Text Available Spontaneous tegmen tympani defects are rare with even rarer bilateral cases. The symptoms are nonspecific; hence, a high index of suspicion is required to prevent serious intracranial complications. We present a case of spontaneous bilateral tegmen tympani defects with associated meningoencephalocoeles in a 54-year-old male who presented with the signs and symptoms of severe meningitis. After careful workup which included a lumbar puncture, CT and MRI scans, both defects were repaired using a middle fossa approach. The patient made an uneventful recovery with complete cessation of otorrhoea and improvement in his hearing.

  17. Spontaneous lung lobe torsion in two pugs.

    Science.gov (United States)

    Rooney, M B; Lanz, O; Monnet, E

    2001-01-01

    Two, young adult, male pugs presented for spontaneous left-cranial lung lobe torsions. Clinical signs associated with these two cases included increased weakness, increased respiratory effort, tachypnea, acute collapse, lethargy, anorexia, and cyanosis. The torsed lung lobes were excised using a thoracoabdominal stapling device without detorsing the lobes. Both dogs recovered uneventfully, and at least one year postoperatively, no clinical abnormalities were noted by their owners. Results of this report suggest that spontaneous lung lobe torsion in pugs occurs and should be a differential diagnosis for pugs with increased respiratory effort, tachypnea, nonproductive cough, acute collapse, cyanosis, and lethargy. Surgical excision may be curative.

  18. Spontaneous symmetry breaking in gauge theories.

    Science.gov (United States)

    Kibble, T W B

    2015-01-13

    The aim of this historical article is to describe the development of the idea of spontaneous symmetry breaking in gauge theories as seen from my perspective as a member of Abdus Salam's group at Imperial College London, UK. Beginning with an account of particle physics in the years after the Second World War, I describe early attempts at constructing a unified theory of weak and electromagnetic interactions, the obstacles encountered and how they were eventually overcome with the mass-generating mechanism incorporating the idea of spontaneous symmetry breaking, one of whose features is the now-famous Higgs boson.

  19. Spontaneous subdural hematoma associated to Duret hemorrhage

    Directory of Open Access Journals (Sweden)

    William Alves Martins, MD

    2015-03-01

    Full Text Available Subdural hematoma (SH is a neurosurgical emergency, usually caused by head trauma. Non-traumatic causes include aneurysm or arterial–venous malformation rupture, coagulopathy and others. We report the case of a 66 year-old man who developed apparently unprovoked signs of increased intracranial pressure. Brain computed tomography scan showed an acute spontaneous SH, surgically treated. Throughout surgery, a ruptured cortical artery with intensive bleeding appeared and was cauterized. After surgery, patient remained comatose and a new CT demonstrated Duret hemorrhage at the brainstem. Acute spontaneous SH of arterial origin is rare and highly lethal, in which a good prognosis relies on early diagnosis and treatment.

  20. Primer on spontaneous heating and pyrophoricity

    Energy Technology Data Exchange (ETDEWEB)

    1994-12-01

    This primer was prepared as an information resource for personnel responsible for operation of DOE nuclear facilities. It has sections on combustion principles, spontaneous heating/ignition of hydrocarbons and organics, pyrophoric gases and liquids, pyrophoric nonmetallic solids, pyrophoric metals (including Pu and U), and accident case studies. Although the information in this primer is not all-encompassing, it should provide the reader with a fundamental knowledge level sufficient to recognize most spontaneous combustion hazards and how to prevent ignition and widespread fires. This primer is provided as an information resource only, and is not intended to replace any fire protection or hazardous material training.

  1. Proteomic Biomarkers for Spontaneous Preterm Birth

    DEFF Research Database (Denmark)

    Kacerovsky, Marian; Lenco, Juraj; Musilova, Ivana

    2014-01-01

    This review aimed to identify, synthesize, and analyze the findings of studies on proteomic biomarkers for spontaneous preterm birth (PTB). Three electronic databases (Medline, Embase, and Scopus) were searched for studies in any language reporting the use of proteomic biomarkers for PTB published...

  2. Maternal Factors Associated With Early Spontaneous Singleton ...

    African Journals Online (AJOL)

    Background: Knowledge of the maternal factors predisposing to preterm deliveries should affect the anticipatory care of mothers at risk of delivering preterm babies and improve perinatal outcome. Objective: To determine the maternal socio-biological characteristics associated with the delivery of early spontaneous ...

  3. Spontaneous Hedonic Reactions to Social Media Cues.

    Science.gov (United States)

    van Koningsbruggen, Guido M; Hartmann, Tilo; Eden, Allison; Veling, Harm

    2017-05-01

    Why is it so difficult to resist the desire to use social media? One possibility is that frequent social media users possess strong and spontaneous hedonic reactions to social media cues, which, in turn, makes it difficult to resist social media temptations. In two studies (total N = 200), we investigated less-frequent and frequent social media users' spontaneous hedonic reactions to social media cues using the Affect Misattribution Procedure-an implicit measure of affective reactions. Results demonstrated that frequent social media users showed more favorable affective reactions in response to social media (vs. control) cues, whereas less-frequent social media users' affective reactions did not differ between social media and control cues (Studies 1 and 2). Moreover, the spontaneous hedonic reactions to social media (vs. control) cues were related to self-reported cravings to use social media and partially accounted for the link between social media use and social media cravings (Study 2). These findings suggest that frequent social media users' spontaneous hedonic reactions in response to social media cues might contribute to their difficulties in resisting desires to use social media.

  4. Controlling spontaneous combustion in surface coal mines

    Energy Technology Data Exchange (ETDEWEB)

    Eroglu, N.

    2005-07-01

    The Witbank Coalfield in South Africa has historically been mined out using the bord-and-pillar method, with typically low coal-recovery ratios, leaving significant amounts of coal in pillars and as floor and roof coal. These pillars are being re-extracted by underground and surface mining methods. During surface mining, air enters through the cracks and bords into the old workings, causing spontaneous combustion of coal. Over the long term, air will also enter the old underground bord-and-pillar workings at shallow depth through sinkholes caused by bord collapse underground. The resulting environmental problems may necessitate future rehabilitation at great cost. Existing knowledge about spontaneous combustion in opencast collieries indicates that there is no typical fire and certainly no standard technique for preventing it from happening. However, with current measures it is possible to control the spontaneous combustion of coal in opencast collieries. A project supported by Coaltech 2020, a South African coal mining Collaborative Research Programme, has been completed to develop methods for minimising and controlling spontaneous combustion in old workings by surface mining methods and applications. However, the findings and recommendations of this study, which focused on the Witbank Coalfield, can be adapted to other surface coal mines. 11 figs.

  5. Association between Nutritional Status with Spontaneous Abortion

    Directory of Open Access Journals (Sweden)

    Rahimeh Ahmadi

    2016-11-01

    Full Text Available Background: Spontaneous abortion is the most common adverse pregnancy outcome. We aimed to investigate a possible link between nutrient deficiencies and the risk of spontaneous abortion. Materials and Methods: This case-control study included the case group (n=331 experiencing a spontaneous abortion before 14 weeks of pregnancy and the control group (n=331 who were healthy pregnant women over 14 weeks of pregnancy. The participants filled out Food Frequency Questionnaire (FFQ, in which they reported their frequency of consumption for a given serving of each food item during the past three months, on a daily, weekly or monthly basis. The reported frequency for each food item was converted to a daily intake. Then, consumption of nutrients was compared between the two groups. Results: There are significant differences between the two groups regarding consumed servings/day of vegetables, bread and cereal, meat, poultry, fish, eggs, beans, fats, oils and dairy products (P=0.012, P<0.001, P=0.004, P<0.001, P=0.019, respectively. There are significant differences between the two groups in all micronutrient including folic acid, iron, vitamin C, vitamin B6, vitamin B12 and zinc (P<0.001. Conclusion: Poor nutrientions may be correlated with increased risk of spontaneous abortion

  6. Synchronization of cubic distortion spontaneous otoacoustic emissions

    NARCIS (Netherlands)

    van Dijk, P; Wit, HP

    A spontaneous otoacoustic emission spectrum may contain equally spaced emission peaks. Then, two peaks, at frequencies, f(1) and f(2), respectively, apparently generate a distortion product at f(d)=2f(1)-f(2) [or 2f(2)-f(1)]. For the three emission peaks of nine of such triplets tin six emission

  7. Spontaneous regression of an intraspinal disc cyst

    Energy Technology Data Exchange (ETDEWEB)

    Demaerel, P.; Eerens, I.; Wilms, G. [University Hospital, Leuven (Belgium). Dept. of Radiology; Goffin, J. [Dept. of Neurosurgery, University Hospitals, Leuven (Belgium)

    2001-11-01

    We present a patient with a so-called disc cyst. Its location in the ventrolateral epidural space and its communication with the herniated disc are clearly shown. The disc cyst developed rapidly and regressed spontaneously. This observation, which has not been reported until now, appears to support focal degeneration with cyst formation as the pathogenesis. (orig.)

  8. Spontaneous Monochorionic Tetra‑amniotic Quadruplet Pregnancy ...

    African Journals Online (AJOL)

    Ron-El R, Mor Z, Weinraub Z, Schreyer P, Bukovsky I, Dolphin Z, et al. Triplet, quadruplet and quintuplet pregnancies: Management and outcome. Acta Obstet Gynaecol Scand 1992;71:347-50. How to cite this article: Nnadi D, Ibrahim A, Nwobodo E. Spontaneous monochorionic tetra-amniotic quadruplet pregnancy at term.

  9. Ovarian hyperstimulation syndrome in a spontaneous pregnancy ...

    African Journals Online (AJOL)

    It is known that most cases of Ovarian Hyperstimulation Syndrome (OHSS) are associated with the therapies for ovulation induction. However, OHSS may rarely be associated with a spontaneous ovulatory cycle, usually in the case of multiple gestations, hypothyroidism or polycystic ovary syndrome. We report a case of ...

  10. Surgical management of spontaneous ruptured hepatocellular adenoma

    Directory of Open Access Journals (Sweden)

    Marcelo Augusto Fontenelle Ribeiro Junior

    2009-01-01

    Full Text Available AIMS: Spontaneous ruptured hepatocellular adenoma (SRHA is a rare life-threatening condition that may require surgical treatment to control hemorrhaging and also stabilize the patient. We report a series of emergency surgeries performed at our institution for this condition. METHODS: We reviewed medical records and radiology files of 28 patients (from 1989 to 2006 with a proven diagnosis of hepatocellular adenoma (HA. Three (10.7% of 28 patients had spontaneous ruptured hepatocellular adenoma, two of which were associated with intrahepatic hemorrhage while one had intraperitoneal bleeding. Two patients were female and one was male. Both female patients had a background history of oral contraceptive use. Sudden abdominal pain associated with hemodynamic instability occurred in all patients who suffered from spontaneous ruptured hepatocellular adenoma. The mean age was 41.6 years old. The preoperative assessment included liver function tests, ultrasonography and computed tomography. RESULTS: The surgical approaches were as follows: right hemihepatectomy for controlling intraperitoneal bleeding, and right extended hepatectomy and non-anatomic resection of the liver for intrahepatic hemorrhage. There were no deaths, and the postoperative complications were bile leakage and wound infection (re-operation, as well as intraperitoneal abscess (re-operation and pleural effusion. CONCLUSION: Spontaneous ruptured hepatocellular adenoma may be treated by surgery for controlling hemorrhages and stabilizing the patient, and the decision to operate depends upon both the patient's condition and the expertise of the surgical team.

  11. Spontaneous Dimensional Reduction in Quantum Gravity

    CERN Document Server

    Carlip, S

    2016-01-01

    Hints from a number of different approaches to quantum gravity point to a phenomenon of "spontaneous dimensional reduction" to two spacetime dimensions near the Planck scale. I examine the physical meaning of the term "dimension" in this context, summarize the evidence for dimensional reduction, and discuss possible physical explanations.

  12. A Case of Idiopathic Spontaneous Intratesticular Hemorrhage

    Directory of Open Access Journals (Sweden)

    Takumi Takeuchi

    2017-09-01

    On visual inspection, the whole testis was black. The spermatic cord was neither distorted nor black. Testicular torsion could not be completely ruled out; thus, left orchiectomy was performed. Histopathology revealed diffuse intratesticular hemorrhage without the necrosis of seminiferous tubular cells. We encountered a case of idiopathic spontaneous intratesticular hemorrhage.

  13. Spontaneous Sourcing among Students Reading Multiple Documents

    Science.gov (United States)

    Stromso, Helge I.; Braten, Ivar; Britt, M. Anne; Ferguson, Leila E.

    2013-01-01

    This study used think-aloud methodology to explore undergraduates' spontaneous attention to and use of source information while reading six documents that presented conflicting views on a controversial social scientific issue in a Google-like environment. Results showed that students explicitly and implicitly paid attention to sources of documents…

  14. Spontaneous Type 2 Diabetic Rodent Models

    Directory of Open Access Journals (Sweden)

    Yang-wei Wang

    2013-01-01

    Full Text Available Diabetes mellitus, especially type 2 diabetes (T2DM, is one of the most common chronic diseases and continues to increase in numbers with large proportion of health care budget being used. Many animal models have been established in order to investigate the mechanisms and pathophysiologic progress of T2DM and find effective treatments for its complications. On the basis of their strains, features, advantages, and disadvantages, various types of animal models of T2DM can be divided into spontaneously diabetic models, artificially induced diabetic models, and transgenic/knockout diabetic models. Among these models, the spontaneous rodent models are used more frequently because many of them can closely describe the characteristic features of T2DM, especially obesity and insulin resistance. In this paper, we aim to investigate the current available spontaneous rodent models for T2DM with regard to their characteristic features, advantages, and disadvantages, and especially to describe appropriate selection and usefulness of different spontaneous rodent models in testing of various new antidiabetic drugs for the treatment of type 2 diabetes.

  15. Spontaneous type 2 diabetic rodent models.

    Science.gov (United States)

    Wang, Yang-Wei; Sun, Guang-Dong; Sun, Jing; Liu, Shu-Jun; Wang, Ji; Xu, Xiao-Hong; Miao, Li-Ning

    2013-01-01

    Diabetes mellitus, especially type 2 diabetes (T2DM), is one of the most common chronic diseases and continues to increase in numbers with large proportion of health care budget being used. Many animal models have been established in order to investigate the mechanisms and pathophysiologic progress of T2DM and find effective treatments for its complications. On the basis of their strains, features, advantages, and disadvantages, various types of animal models of T2DM can be divided into spontaneously diabetic models, artificially induced diabetic models, and transgenic/knockout diabetic models. Among these models, the spontaneous rodent models are used more frequently because many of them can closely describe the characteristic features of T2DM, especially obesity and insulin resistance. In this paper, we aim to investigate the current available spontaneous rodent models for T2DM with regard to their characteristic features, advantages, and disadvantages, and especially to describe appropriate selection and usefulness of different spontaneous rodent models in testing of various new antidiabetic drugs for the treatment of type 2 diabetes.

  16. [Spontaneous remission of objective tinnitus (author's transl)].

    Science.gov (United States)

    Chilla, R; Nordeck, E

    1975-09-01

    The presence of a systolic loud tinnitus over the right mastoid in a 21 year old male was established by auscultation and phonocardiograph recording. Selective angiography of the carotids excluded a vascular abnormality. The tinnitus, which persited for 1 year, disappeared spontaneously over a 4 week period. The cause and the course of this tinnitus are discussed.

  17. Massive Spontaneous Hemothorax, Giant Intrathoracic Meningocele ...

    African Journals Online (AJOL)

    Massive Spontaneous Hemothorax, Giant Intrathoracic. Meningocele, and Kyphoscoliosis in Neurofibromatosis Type 1. Ayodeji Salman Yusuf, Ashok Pillai1, Sajesh K. Menon1, Dilip Panikar1. INTRODUCTION. Neurofibromatosis type 1 (NF‑1) is an autosomal dominant disease with an incidence ranging from. 1 in 2500 to ...

  18. Spontaneous emission from saturated parametric amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Ott, Johan Raunkjær; Steffensen, Henrik

    2009-01-01

    Noise performance of parametric amplifiers is typically calculated assuming un-depleted operation. However, in many applications especially when applied as regenerative amplifiers in systems based on phase shift keyed modulation schemes, this assumption is not valid. Here we show the impact...... on accumulated spontaneous emission for a parametric amplifier operated in saturation....

  19. Identical Twin Primigravid Sisters -Spontaneous Labour and ...

    African Journals Online (AJOL)

    We report 2 cases of identical twin sisters, the older sibling getting married 14 months earlier but both got pregnant for their first child at about the same time and were managed by the same Obstetrician and fell into spontaneous labour within a few hours of each other. Both were delivered by emergency caesarean section ...

  20. Influence of spontaneous fermentation on some quality ...

    African Journals Online (AJOL)

    Spontaneous fermentation has been identified to improve the quality characteristics of foods derived from them. When combined with cowpea fortification and nixtamalization, it is expected to improve the nutritional, functional, physico- chemical and sensory qualities of maize based foods thereby improving the qualities as ...

  1. Spontaneous Non-verbal Counting in Toddlers

    Science.gov (United States)

    Sella, Francesco; Berteletti, Ilaria; Lucangeli, Daniela; Zorzi, Marco

    2016-01-01

    A wealth of studies have investigated numerical abilities in infants and in children aged 3 or above, but research on pre-counting toddlers is sparse. Here we devised a novel version of an imitation task that was previously used to assess spontaneous focusing on numerosity (i.e. the predisposition to grasp numerical properties of the environment)…

  2. Spatial Memory in Spontaneously Hypertensive Rats (SHR)

    NARCIS (Netherlands)

    Sontag, Thomas-A.; Fuermaier, Anselm B. M.; Hauser, Joachim; Kaunzinger, Ivo; Tucha, Oliver; Lange, Klaus W.

    2013-01-01

    The spontaneously hypertensive rat (SHR) is an established animal model of ADHD. It has been suggested that ADHD symptoms arise from deficits in executive functions such as working memory, attentional control and decision making. Both ADHD patients and SHRs show deficits in spatial working memory.

  3. Spontaneous baroreflex sensitivity in (pre)adolescents

    NARCIS (Netherlands)

    Dietrich, A; Riese, H; van Roon, AM; van Engelen, K; Ormel, J; Neeleman, J; Rosmalen, JGM

    Objective To present normal spontaneous baroreflex sensitivity (BRS) values and investigate the influence of posture, sex, age, pubertal stage, body mass index (BMI), , and physical activity level on BRS in (pre)adolescents. BRS is a sensitive measure of both sympathetic and parasympathetic

  4. Massive Spontaneous Hemothorax, Giant Intrathoracic Meningocele ...

    African Journals Online (AJOL)

    Neurofibromatosis type 1 (NF‑1) is a heterogeneous autosomal dominant disease with an incidence ranging from 1 in 2500 to 1 in 3000. Rare intrathoracic vascular disorders resulting in massive spontaneous hemothorax with fatal consequences may occur in these patients, so also are various types of skeletal dysplasia ...

  5. Spontaneous Language Markers of Spanish Language Impairment

    Science.gov (United States)

    Simon-Cereijido, Gabriela; Gutierrez-Clellen, Vera F.

    2007-01-01

    Spanish-speaking (SS) children with language impairment (LI) present with deficits in morphology and verb argument structure. These language areas may be useful for clinical identification of affected children. This study aimed to evaluate the discrimination accuracy of spontaneous language measures with SS preschoolers to tease out what…

  6. PERIODIC-SOLUTIONS IN SPONTANEOUSLY BROKEN THEORIES

    NARCIS (Netherlands)

    BRIHAYE, Y; KUNZ, J

    A class of spontaneously broken field theories is proposed, and the occurrence of their periodic, classical solutions is investigated in detail. The emergence of multiple solutions is observed, their normal modes of oscillation are studied, and the bifurcations of the classical energy functional are

  7. Editorial: Spontaneous bacterial peritonitis | Lule | East African ...

    African Journals Online (AJOL)

    Journal Home > Vol 81, No 3 (2004) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. Editorial: Spontaneous bacterial peritonitis. GN Lule. Abstract. No Abstract Available. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT ...

  8. Spontaneous hedonic reactions to social media cues

    NARCIS (Netherlands)

    Koningsbruggen, G.M. van; Hartmann, T.; Eden, A.; Veling, H.P.

    2017-01-01

    Why is it so difficult to resist the desire to use social media? One possibility is that frequent social media users possess strong and spontaneous hedonic reactions to social media cues, which, in turn, makes it difficult to resist social media temptations. In two studies (total N = 200), we

  9. Silicon photonic crystals and spontaneous emission

    NARCIS (Netherlands)

    Dood, Michiel Jacob Andries de

    2002-01-01

    Photonic crystals, i.e. materials that have a periodic variation in refractive index, form an interesting new class of materials that can be used to modify spontaneous emission and manipulate optical modes in ways that were impossible so far. This thesis is divided in three parts. Part I discusses

  10. Spontaneous Symmetry Breaking in Nonrelativistic Systems

    Science.gov (United States)

    Watanabe, Haruki

    The subject of condensed matter physics is very rich --- there are an infinite number of parameters producing a diversity of exciting phenomena. As a theorist, my goal is to distill general principles out of this complexity --- to construct theories that can coherently explain many known examples altogether. This thesis is composed of several attempts to develop such theories in topics related to spontaneously symmetry breaking. A remarkable feature of many-body interacting systems is that although they are described by equations respecting various symmetries, they may spontaneously organize into a state that explicitly breaks symmetries. Examples are numerous: various types of crystalline and magnetic orders, Bose-Einstein condensates of cold atoms, superfluids of liquid helium, chiral symmetry in QCD, neutron stars, and cosmic inflation. These systems with spontaneously broken continuous symmetries have gapless excitations, so called Nambu-Goldstone bosons (NGBs). Although the properties of NGBs are well understood in Lorentz-invariant systems, surprisingly, some basic properties of NGBs such as their number and dispersion in nonrelativistic systems have not been discussed from a general perspective. In the first part of this thesis, we solve this issue by developing and analyzing an effective Lagrangian that coherently captures the low-energy, long-distance physics of many different symmetry-breaking states all at once. Next, we examine whether these NGBs originating from spontaneous symmetry breaking remain to be well-defined excitations inside a metal, where low-energy electrons near Fermi surface can collide with them. Our result is a one equation criterion that specifies whether the interactions between electrons and NGBs can be ignored, or whether it completely changes their character. In the latter case, unusual phases of matter such as non-Fermi liquids may arise; in that case, NGBs are overdamped and cannot form particle-like excitations in spite of the

  11. Genetic polymorphisms and spontaneous preterm birth.

    Science.gov (United States)

    Gibson, Catherine S; MacLennan, Alastair H; Dekker, Gustaaf A; Goldwater, Paul N; Dambrosia, James M; Munroe, David J; Tsang, Shirley; Stewart, Claudia; Nelson, Karin B

    2007-02-01

    To examine whether selected genetic polymorphisms in the infant are associated with spontaneous preterm birth (less than 37 weeks) among children with or without later-diagnosed cerebral palsy. Exploratory case-control study investigating the relationship of gestational age at delivery to 31 single nucleotide polymorphisms measured in newborn screening bloodspots. Among all 443 children with later-diagnosed cerebral palsy born to white women in South Australia in 1986-1999, 234 were born after spontaneous onset of labor, and 108 of these were preterm (gestational age less than 37 weeks). The comparison group was 549 infants born after spontaneous onset of labor, of whom 147 were preterm. Distributions of genotypic frequencies were examined in preterm compared with term infants with and without cerebral palsy. Genotyping was performed using a Taqman assay. In children without cerebral palsy, preterm birth after spontaneous onset of labor was more frequent in association with a variant of the beta2 adrenergic receptor gene (ADRB2 Q27E, P=.003), inducible nitric oxide synthase (iNOS or NOS2A, P=.042), or thrombomodulin (G127A, P=.006). Among children with cerebral palsy, preterm birth was associated with polymorphisms in genes for endothelial nitric oxide synthase (eNOS -922, P=.012), plasminogen activator inhibitor-2 (P=.015 and .019), and alpha adducin (ADD1, P=.047). We confirm previous observations that variants of the beta adrenergic receptor and of nitric oxide synthase are associated with prematurity, and suggest that genetic variants of the placental antifibrinolytic plasminogen activator inhibitor-2, and thrombomodulin and alpha adducin may be contributors to risk of spontaneous preterm birth. II.

  12. Spontaneous sensorimotor coupling with multipart music.

    Science.gov (United States)

    Hurley, Brian K; Martens, Peter A; Janata, Petr

    2014-08-01

    Music often evokes spontaneous movements in listeners that are synchronized with the music, a phenomenon that has been characterized as being in "the groove." However, the musical factors that contribute to listeners' initiation of stimulus-coupled action remain unclear. Evidence suggests that newly appearing objects in auditory scenes orient listeners' attention, and that in multipart music, newly appearing instrument or voice parts can engage listeners' attention and elicit arousal. We posit that attentional engagement with music can influence listeners' spontaneous stimulus-coupled movement. Here, 2 experiments-involving participants with and without musical training-tested the effect of staggering instrument entrances across time and varying the number of concurrent instrument parts within novel multipart music on listeners' engagement with the music, as assessed by spontaneous sensorimotor behavior and self-reports. Experiment 1 assessed listeners' moment-to-moment ratings of perceived groove, and Experiment 2 examined their spontaneous tapping and head movements. We found that, for both musically trained and untrained participants, music with more instruments led to higher ratings of perceived groove, and that music with staggered instrument entrances elicited both increased sensorimotor coupling and increased reports of perceived groove. Although untrained participants were more likely to rate music as higher in groove, trained participants showed greater propensity for tapping along, and they did so more accurately. The quality of synchronization of head movements with the music, however, did not differ as a function of training. Our results shed new light on the relationship between complex musical scenes, attention, and spontaneous sensorimotor behavior.

  13. Mixing in explosions

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, A.L.

    1993-12-01

    Explosions always contain embedded turbulent mixing regions, for example: boundary layers, shear layers, wall jets, and unstable interfaces. Described here is one particular example of the latter, namely, the turbulent mixing occurring in the fireball of an HE-driven blast wave. The evolution of the turbulent mixing was studied via two-dimensional numerical simulations of the convective mixing processes on an adaptive mesh. Vorticity was generated on the fireball interface by baroclinic effects. The interface was unstable, and rapidly evolved into a turbulent mixing layer. Four phases of mixing were observed: (1) a strong blast wave phase; (2) and implosion phase; (3) a reshocking phase; and (4) an asymptotic mixing phase. The flowfield was azimuthally averaged to evaluate the mean and r.m.s. fluctuation profiles across the mixing layer. The vorticity decayed due to a cascade process. This caused the corresponding enstrophy parameter to increase linearly with time -- in agreement with homogeneous turbulence calculations of G.K. Batchelor.

  14. Socioeconomic position and the risk of spontaneous abortion

    DEFF Research Database (Denmark)

    Norsker, Filippa Nyboe; Espenhain, Laura; A Rogvi, Sofie

    2012-01-01

    To investigate the relationship between different indicators of socioeconomic position and the risk of spontaneous abortion.......To investigate the relationship between different indicators of socioeconomic position and the risk of spontaneous abortion....

  15. Spontaneous Perinephric Hemorrhage Associated with Urolithiasis in Pregnancy

    Directory of Open Access Journals (Sweden)

    Leah P. McMann

    2004-01-01

    Full Text Available Spontaneous perinephric hematoma in the absence of anticoagulation, arteritis, or trauma is uncommon. We report the case of a postpartum patient with nephrolithiasis who initially presented to the obstetric service with a spontaneous perinephric hemorrhage.

  16. Detection of target phonemes in spontaneous and read speech

    NARCIS (Netherlands)

    Mehta, G.; Cutler, A.

    1988-01-01

    Although spontaneous speech occurs more frequently in most listeners' experience than read speech, laboratory studies of human speech recognition typically use carefully controlled materials read from a script. The phonological and prosodic characteristics of spontaneous and read speech differ

  17. Visually Evoked Spiking Evolves While Spontaneous Ongoing Dynamics Persist

    DEFF Research Database (Denmark)

    Huys, Raoul; Jirsa, Viktor K; Darokhan, Ziauddin

    2016-01-01

    attractor. Its existence guarantees that evoked spiking return to the spontaneous state. However, the spontaneous ongoing spiking state and the visual evoked spiking states are qualitatively different and are separated by a threshold (separatrix). The functional advantage of this organization...

  18. Optimal Mixing Evolutionary Algorithms

    NARCIS (Netherlands)

    D. Thierens (Dirk); P.A.N. Bosman (Peter); N. Krasnogor

    2011-01-01

    htmlabstractA key search mechanism in Evolutionary Algorithms is the mixing or juxtaposing of partial solutions present in the parent solutions. In this paper we look at the efficiency of mixing in genetic algorithms (GAs) and estimation-of-distribution algorithms (EDAs). We compute the mixing

  19. Mixed methods research.

    Science.gov (United States)

    Halcomb, Elizabeth; Hickman, Louise

    2015-04-08

    Mixed methods research involves the use of qualitative and quantitative data in a single research project. It represents an alternative methodological approach, combining qualitative and quantitative research approaches, which enables nurse researchers to explore complex phenomena in detail. This article provides a practical overview of mixed methods research and its application in nursing, to guide the novice researcher considering a mixed methods research project.

  20. [Bacterial vaginosis and spontaneous preterm birth].

    Science.gov (United States)

    Brabant, G

    2016-12-01

    To determine if bacterial vaginosis is a marker for risk of spontaneous preterm delivery and if its detection and treatment can reduce this risk. Consultation of the database Pubmed/Medline, Science Direct, and international guidelines of medical societies. Bacterial vaginosis (BV) is a dysbiosis resulting in an imbalance in the vaginal flora through the multiplication of anaerobic bacteria and jointly of a disappearance of well-known protective Lactobacilli. His diagnosis is based on clinical Amsel criteria and/or a Gram stain with establishment of the Nugent score. The prevalence of the BV extraordinarily varies according to ethnic and/or geographical origin (4-58 %), in France, it is close to 7 % in the first trimester of pregnancy (EL2). The link between BV and spontaneous premature delivery is low with an odds ratio between 1.5 and 2 in the most recent studies (EL3). Metronidazole or clindamycin is effective to treat BV (EL3). It is recommended to prescribe one of these antibiotics in the case of symptomatic BV (Professional Consensus). The testing associated with the treatment of BV in the global population showed no benefit in the prevention of the risk of spontaneous preterm delivery (EL2). Concerning low-risk asymptomatic population (defined by the absence of antecedent of premature delivery), it has been failed profit to track and treat the BV in the prevention of the risk of spontaneous preterm delivery (EL1). Concerning the high-risk population (defined by a history of preterm delivery), it has been failed profit to track and treat the VB in the prevention of the risk of spontaneous preterm delivery (EL3). However, in the sub population of patients with a history of preterm delivery occurred in a context of materno-fetal bacterial infection, there may be a benefit to detect and treat early and systematically genital infection, and in particular the BV (Professional Consensus). The screening and treatment of BV during pregnancy in asymptomatic low

  1. Mixing of solids in different mixing devices

    Indian Academy of Sciences (India)

    as devices for powder mixing, are tested as well as Turbula and V-shaped drum mixer, since those devices .... 1679·90. 13 force on the particles exceeds the pull of gravity), its working capacity is about 50% to 60% of volume. ... In solid/solid mixing the unit is usually vertical with the flow being by gravity only. The material is ...

  2. F. VON HAYEK’S THEORY OF SPONTANEOUS ORDER

    Directory of Open Access Journals (Sweden)

    О. Nesterenko

    2013-04-01

    Full Text Available The essence and the genesis of spontaneous order are disclosed in the context of critical analysis of constructivism. The author’s approach to the definition of the characteristic features of the spontaneous order is proposed. The dichotomy of the order is revealed towards the economic sphere in form of spontaneous order and organization.

  3. Gravid med spontan ruptur af arteria uterina

    DEFF Research Database (Denmark)

    Jònsdòttir, Fjòla; Pinborg, Anja; Wilken-Jensen, Charlotte

    2014-01-01

    Pregnant women with acute abdominal pain are a clinical challenge. We present a rare but potential life-threatening condition of a pregnant woman with acute abdominal pain. The woman was in gestational week 37 with severe abdominal pain and was admitted to the labour ward. She became haemo-dynami......-dynamic instable 24 hours after vaginal delivery, and emergency laparotomi revealed a spontaneous rupture of the right uterine artery. Spontaneous rupture of the uterine artery is rare but should be considered as a possible cause of acute abdominal pain in pregnant women.......Pregnant women with acute abdominal pain are a clinical challenge. We present a rare but potential life-threatening condition of a pregnant woman with acute abdominal pain. The woman was in gestational week 37 with severe abdominal pain and was admitted to the labour ward. She became haemo...

  4. Spontaneously disappearing large herniated lumbar disc fragment

    Directory of Open Access Journals (Sweden)

    Umamaheswara V. Reddy

    2014-01-01

    Full Text Available There are reports of spontaneous regression of large extruded disc; however, the exact underlying mechanism and management of such cases remains controversial. We report a 40-year-old female who opted for conservative management for a large extruded lumbar disc. Follow-up magnetic resonance imaging (MRI showed complete disappearance of the disc fragment; however, there were degenerative changes in the upper and lower adjacent margins of the vertebral body. Spine surgeons should be aware of spontaneous regression of the disc phenomenon as a patient with a large extruded disc who opted for the conservative management initially can have persistence pain, but there may not be an underlying protruded disc.

  5. Characteristics of spontaneous fission of 250No

    Science.gov (United States)

    Svirikhin, A. I.; Andreev, A. V.; Yeremin, A. V.; Izosimov, I. N.; Isaev, A. V.; Kuznetsov, A. N.; Kuznetsova, A. A.; Malyshev, O. N.; Popeko, A. G.; Popov, Y. A.; Sokol, E. A.; Chelnokov, M. L.; Chepigin, V. I.; Schneidman, T. M.; Gall, B.; Dorvaux, O.; Brione, P.; Hauschild, K.; Lopez-Martenz, A.; Rezynkina, K.; Mullins, S.; Jones, P.; Mosat, P.

    2017-07-01

    This study describes an experiment on investigating the properties of spontaneous fission of shortlived neutron-deficient nuclei synthesized in the reaction of complete fusion 48Ca + 204Pb = 252No*. The experiment is performed using the SHELS separator and the beam of multicharged ions at U-400 accelerator (LNR, JINR). Two activities undergoing spontaneous fission, which can be related to the ground and isomeric states of 250No nucleus, are registered. The half-lives, total kinetic energies of fission fragments, and neutron multiplicities are measured for the short-lived nuclei. The average number of neutrons per fission for the activity with t 1/2 = 5.1 ± 0.3 μs is = 4.38 ± 0.13 μs, and for nuclei with the half-life t 1/2 = 36 ± 3 μs it is xxxxx.

  6. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

    Hjøllund, Niels Henrik Ingvar; Jensen, T.K.; Bonde, J.P.

    2000-01-01

    Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short...... time periods are the relevant measure. We followed a cohort of first pregnancy planners from termination of birth control until pregnancy for a maximum of six menstrual cycles. The analyses include 181 pregnancies, of which 32 were subclinical pregnancies detected by hCG analysis only. During early...... pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date...

  7. Spontaneous breaking of continuous translational invariance

    Science.gov (United States)

    Watanabe, Haruki; Brauner, Tomáš

    2012-04-01

    Unbroken continuous translational invariance is often taken as a basic assumption in discussions of spontaneous symmetry breaking (SSB), which singles out SSB of translational invariance itself as an exceptional case. We present a framework that allows us to treat translational invariance on the same footing as other symmetries. It is shown that existing theorems on SSB can be straightforwardly extended to this general case. As a concrete application, we analyze the Nambu-Goldstone modes in a (ferromagnetic) supersolid. We prove on the ground of the general theorems that the Bogoliubov mode stemming from a spontaneously broken internal U(1) symmetry and the longitudinal phonon due to a crystalline order are distinct physical modes.

  8. Spontaneous stress fractures of the femoral neck

    Energy Technology Data Exchange (ETDEWEB)

    Dorne, H.L.; Lander, P.H.

    1985-02-01

    The diagnosis of spontaneous stress fractures of the femoral neck, a form of insufficiency stress fracture, can be missed easily. Patients present with unremitting hip pain without a history of significant trauma or unusual increase in daily activity. The initial radiographic features include osteoporosis, minor alterations of trabecular alignment, minimal extracortical or endosteal reaction, and lucent fracture lines. Initial scintigraphic examinations performed in three of four patients showed focal increased radionuclide uptake in two and no focal abnormality in one. Emphasis is placed on the paucity of early findings. Evaluation of patients with persistent hip pain requires a high degree of clinical suspicion and close follow-up; the sequelae of undetected spontaneous fractures are subcapital fracture with displacement, angular deformity, and a vascular necrosis of the femoral head.

  9. Laboratory observations of spontaneous magnetic reconnection.

    Science.gov (United States)

    Egedal, J; Fox, W; Katz, N; Porkolab, M; Reim, K; Zhang, E

    2007-01-05

    Detailed measurements of spontaneous magnetic reconnection are presented. The experimental data, which were obtained in the new closed Versatile Toroidal Facility magnetic configuration, document the profile evolution of the plasma density, magnetic flux function, reconnection rate, and the current density during a spontaneous reconnection event in the presence of a strong guide magnetic field. The reconnection process is at first slow, which allows magnetic stress to build in the system while the current channel becomes increasingly narrow and intense. The onset of a fast reconnection event occurs as the width of the current channel approaches the ion-sound-Larmor radius rho s. During the reconnection event magnetically stored energy is channeled into energetic ion outflows and a rapid increase in the electron temperature.

  10. Motivational Projections of Russian Spontaneous Speech

    Directory of Open Access Journals (Sweden)

    Galina M. Shipitsina

    2017-06-01

    Full Text Available The article deals with the semantic, pragmatic and structural features of words, phrases, dialogues motivation, in the contemporary Russian popular speech. These structural features are characterized by originality and unconventional use. Language material is the result of authors` direct observation of spontaneous verbal communication between people of different social and age groups. The words and remarks were analyzed in compliance with the communication system of national Russian language and cultural background of popular speech. Studies have discovered that in spoken discourse there are some other ways to increase the expression statement. It is important to note that spontaneous speech identifies lacunae in the nominative language and its vocabulary system. It is proved, prefixation is also effective and regular way of the same action presenting. The most typical forms, ways and means to update language resources as a result of the linguistic creativity of native speakers were identified.

  11. Mixing and compaction temperatures for Superpave mixes

    Science.gov (United States)

    Yildirim, Yetkin

    According to Superpave mixture design, gyratory specimens are mixed and compacted at equiviscous binder temperatures corresponding to viscosities of 0.17 and 0.28 Pa.s. respectively. These were the values previously used in the Marshal mix design method to determine optimal mixing and compaction temperatures. In order to estimate the appropriate mixing and compaction temperatures for Superpave mixture design, a temperature-viscosity relationship for the binder needs to be developed (ASTM D 2493, Calculation of Mixing and Compaction Temperatures). The current approach is simple and provides reasonable temperatures for unmodified binders. However, some modified binders have exhibited unreasonably high temperatures for mixing and compaction using this technique. These high temperatures can result in construction problems, damage of asphalt, and production of fumes. Heating asphalt binder to very high temperatures during construction oxidizes the binder and separates the polymer from asphalt binder. It is known that polymer modified asphalt binders have many benefits to the roads, such as; increasing rutting resistance, enhancing low temperature cracking resistance, improving traction, better adhesion and cohesion, elevating tensile strength which are directly related to the service life of the pavement. Therefore, oxidation and separation of the polymer from the asphalt binder results in reduction of the service life. ASTM D 2493 was established for unmodified asphalt binders which are Newtonian fluids at high temperatures. For these materials, viscosity does not depend on shear rate. However, most of the modified asphalt binders exhibit a phenomenon known as pseudoplasticity, where viscosity does depend on shear rate. Thus, at the high shear rates occurring during mixing and compaction, it is not necessary to go to very high temperatures. This research was undertaken to determine the shear rate during compaction such that the effect of this parameter could be

  12. Leadership and persistency in spontaneous dishonesty

    OpenAIRE

    Braun, Susanne; Hornuf, Lars

    2015-01-01

    Extensive evidence shows that when given the opportunity, people cheat for monetary rewards, but only to the extent that they can keep a positive selfconcept. In this study, we investigate various factors that may influence the degree to which people can keep their positive self-concept while cheating for monetary gains. We find that authentic leadership, gender, cheating norm, experience of cheating, and expectations of others' cheating behavior have no effect on participants' spontaneous di...

  13. Spontaneous intracranial hypotension: use of unenhanced MRI

    Energy Technology Data Exchange (ETDEWEB)

    Quinones Tapia, D.; Lopez-Ibor, L. [Dept. of Neuroradiology, Clinica de La Zarzuela, Aravaca, Madrid (Spain); Pardo, J.; Anciones, V. [Dept. of Neurology, Clinica de La Zarzuela, Aravaca, Madrid (Spain); Serrano, J.M. [Dept. of Ophthalmology, Fundacion Jimenez Diaz, Madrid (Spain)

    2000-07-01

    We report a case of spontaneous intracranial hypotension diagnosed with unenhanced cranial MRI, showing laminar subdural fluid and engorgement of the hypophysis and perisellar sinuses. Cerebrospinal fluid pressure was low. MRI was normal after resolution of symptoms. Prior reports emphasise the enhancing pachymeninges seen in this syndrome. We maintain that, when subdural collections and perisellar engorgement are detected on unenhanced MRI in the proper clinical setting, contrast enhancement may not be necessary for the diagnosis. (orig.)

  14. Short wave diathermy for small spontaneous pneumothorax

    OpenAIRE

    Ma, Y.; Li, J; Liu, Y.

    1997-01-01

    BACKGROUND: The treatment of small spontaneous pneumothorax can involve observation, tube thoracostomy, and surgery. This study evaluated the use of short wave diathermy as a method of accelerating the resolution of small pneumothoraces. METHODS: Twenty two patients with pneumothoraces of less than 30% by volume were randomly allocated to receive short wave diathermy for 25 minutes each day (n = 11) or observation with bed rest (n = 11). Chest radiographs were taken until the pneumothor...

  15. Concentration-Independent Spontaneously Forming Biomimetric Vesicles

    Science.gov (United States)

    Nieh, M.-P.; Harroun, T. A.; Raghunathan, V. A.; Glinka, C. J.; Katsaras, J.

    2003-10-01

    In this Letter we present small-angle neutron scattering data from a biomimetic system composed of the phospholipids dimyristoyl and dihexanoyl phosphorylcholine (DMPC and DHPC, respectively). Doping DMPC-DHPC multilamellar vesicles with either the negatively charged lipid dimyristoyl phosphorylglycerol (DMPG, net charge -1) or the divalent cation, calcium (Ca2+), leads to the spontaneous formation of energetically stabilized monodisperse unilamellar vesicles whose radii are concentration independent and in contrast with previous experimental observations.

  16. Spontaneous remission of MAOI-induced anorgasmia.

    Science.gov (United States)

    Nurnberg, H G; Levine, P E

    1987-06-01

    The authors present three case reports illustrating that a conservative approach to anorgasmia induced by effective treatment with the monoamine oxidase inhibitor (MAOI) phenelzine can result in spontaneous remission. Precipitously stopping phenelzine or adding another medication to counteract the side effect can be avoided. The apparent synchrony between the development of the side effect of anorgasmia and positive treatment response may represent a valuable clinical marker.

  17. Spontaneous bladder rupture in acute alcohol intoxication

    Directory of Open Access Journals (Sweden)

    Bahjat Barakat

    2014-03-01

    Full Text Available Spontaneous bladder rupture is a rare condition that can be followed by an acute alcohol intoxication and can be associated with significant morbidity and mortality. We report a case diagnosed in a alcoholic young male who was admitted to our emergency room for epigastric pain. The case demonstrates the difficulties with diagnosis and the need for physicians who work in an emergency room to be aware of this condition.

  18. Spontaneous Hemocholecyst in an End-Stage Renal Failure Patient on Low Molecular Weight Heparin Hemodialysis

    Directory of Open Access Journals (Sweden)

    Konstantinos Blouhos

    2012-01-01

    Full Text Available The present paper describes a case of spontaneous hemocholecyst in a patient with end-stage renal failure on low molecular weight heparin hemodialysis. The patient presented with acute right upper quadrant pain. An initial ultrasound scan demonstrated a distended gallbladder containing echogenic bile without stones. During hospitalization the patient became febrile, and jaundiced, developed leukocytosis, and had an elevation in serum bilirubin, transaminases, and alkaline phosphatase. A new ultrasound demonstrated a thick-walled gallbladder containing echogenic bile and pericholecystic fluid. MRI depicted a distended gallbladder containing material of mixed signal intensity and a normal biliary tract. Open cholecystectomy revealed a gallbladder filled with blood and clots, and transcystic common bile duct exploration flushed blood clots out of the bile duct. To our knowledge this is the second case of spontaneous hemocholecyst reported in the literature as a consequence of uremic bleeding and LMWH hemodialysis in the absence of other pathology.

  19. A case of mirtazapine-induced spontaneous orgasms in a female patient.

    Science.gov (United States)

    Shalev, H; Ben-Zion, I; Shiber, A

    2009-01-01

    This is a case report of a 51-year-old woman admitted as a psychiatric outpatient with symptoms of moderate to severe depression and anxiety. She had received anti-depressants prior to her admission. The patient did not have a medical history of mania or hypomania, and did not complain of any sexual side-effects when taking prior medications. She was diagnosed in our clinic with mixed anxiety-depressive disorder. Due to lack of improvement she was commenced on mirtazapine and after three days complained of spontaneous orgasms and increased libido. The sexual symptoms resolved gradually after a few days and reappeared upon every dosage increase. On discontinuation of mirtazapine the side effects subsided. To the best of the author's knowledge this is the first report of spontaneous orgasms following treatment with mirtazapine.

  20. Spontaneous fission of the heaviest elements

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, D.C.

    1989-04-01

    Although spontaneous fission was discovered in /sup 238/U in 1940, detailed studies of the process were first made possible in the 1960's with the availability of milligram quantities of /sup 252/Cf. The advent of solid-state detectors made it possible to perform measurements of coincident fission fragments from even very short-lived spontaneous fission activities or those available in only very small quantities. Until 1971 it was believed that the main features of the mass and kinetic-energy distributions were essentially the same as those for thermal neutron-induced fission and that all low-energy fission proceeded via asymmetric mass division with total kinetic energies which could be derived by linear extrapolation from those of lighter elements. In 1971, measurements of /sup 257/Fm showed an increase in symmetric mass division with anomalously high TKE's. Subsequent experiments showed that in /sup 258/Fm and /sup 259/Fm, the most probable mass split was symmetric with very high total kinetic energy. Measurements for the heavier elements have shown symmetric mass distributions with both high and low total kinetic energies. Recent results for spontaneous fission properties of the heaviest elements are reviewed and compared with theory. 31 refs., 8 figs., 1 tab.

  1. Spontaneous Regression of a Cervical Disk Herniation

    Directory of Open Access Journals (Sweden)

    Emre Delen

    2014-03-01

    Full Text Available A 54 years old female patient was admitted to our outpatient clinic with a two months history of muscle spasms of her neck and pain radiating to the left upper extremity. Magnetic resonance imaging had shown a large left-sided paracentral disk herniation at the C6-C7 disk space (Figure 1. Neurological examination showed no obvious neurological deficit. She received conservative treatment including bed rest, rehabilitation, and analgesic drugs. After 13 months, requested by the patient, a second magnetic resonance imaging study showed resolution of the disc herniation.(Figure 2 Although the literature contains several reports about spontaneous regression of herniated lumbar disc without surgical intervention, that of phenomenon reported for herniated cervical level is rare, and such reports are few[1]. In conclusion, herniated intervertebral disc have the potential to spontaneously regress independently from the spine level. With further studies, determining the predictive signs for prognostic evaluation for spontaneous regression which would yield to conservative treatment would be beneficial.

  2. Spontaneous globe luxation in iatrogenic Cushing syndrome.

    Science.gov (United States)

    Ortega-Evangelio, Leticia; Navarrete-Sanchis, Javier; Williams, Basil K; Tomas-Torrent, Juan Miguel

    2015-10-01

    We report a rare case of spontaneous eyeball luxation associated with exophthalmos due to iatrogenic Cushing syndrome (CS). The normalization of serum hormones led to the regression of the picture. A 64-year-old man presented with spontaneous globe luxation of the left eye after a 6-month history of bilateral, painless, and slowly progressive exophthalmos. The patient had been receiving weekly infusions of methylprednisone over the previous 6 months. His best-corrected visual acuity (BCVA) at presentation was 20/40 in the right eye and 20/20 in the left eye. The patient demonstrated full extraocular motility. The intraocular pressure (IOP) was elevated in the right eye (24 mHg) and normal in the left eye (18 mmHg). Exophthalmometry demonstrated bilateral proptosis with measurements of 27 mm in the right eye and 28 mm in the left eye. Computed tomography scan of the brain and orbits revealed increased orbital and cervical fat. Clinical, radiographic and serologic findings ruled out potential diagnoses including orbital metastasis, thyroid orbitopathy, carotid-cavernous fistula, and idiopathic orbital pseudotumor. Clinical suspicion of iatrogenic CS was high, and additional serologic testing confirmed the diagnosis. Exophthalmos is an uncommon sign of CS, but to our knowledge, this is the first reported case of spontaneous globe luxation secondary to CS. In our case, normalization of cortisol was sufficient to resolve the clinical symptoms and eliminated the need for surgical intervention such as orbital decompression surgery.

  3. Spontaneous droplet trampolining on rigid superhydrophobic surfaces

    Science.gov (United States)

    Schutzius, Thomas M.; Jung, Stefan; Maitra, Tanmoy; Graeber, Gustav; Köhme, Moritz; Poulikakos, Dimos

    2015-11-01

    Spontaneous removal of condensed matter from surfaces is exploited in nature and in a broad range of technologies to achieve self-cleaning, anti-icing and condensation control. But despite much progress, our understanding of the phenomena leading to such behaviour remains incomplete, which makes it challenging to rationally design surfaces that benefit from its manifestation. Here we show that water droplets resting on superhydrophobic textured surfaces in a low-pressure environment can self-remove through sudden spontaneous levitation and subsequent trampoline-like bouncing behaviour, in which sequential collisions with the surface accelerate the droplets. These collisions have restitution coefficients (ratios of relative speeds after and before collision) greater than unity despite complete rigidity of the surface, and thus seemingly violate the second law of thermodynamics. However, these restitution coefficients result from an overpressure beneath the droplet produced by fast droplet vaporization while substrate adhesion and surface texture restrict vapour flow. We also show that the high vaporization rates experienced by the droplets and the associated cooling can result in freezing from a supercooled state that triggers a sudden increase in vaporization, which in turn boosts the levitation process. This effect can spontaneously remove surface icing by lifting away icy drops the moment they freeze. Although these observations are relevant only to systems in a low-pressure environment, they show how surface texturing can produce droplet-surface interactions that prohibit liquid and freezing water-droplet retention on surfaces.

  4. Spontaneously emerging cortical representations of visual attributes

    Science.gov (United States)

    Kenet, Tal; Bibitchkov, Dmitri; Tsodyks, Misha; Grinvald, Amiram; Arieli, Amos

    2003-10-01

    Spontaneous cortical activity-ongoing activity in the absence of intentional sensory input-has been studied extensively, using methods ranging from EEG (electroencephalography), through voltage sensitive dye imaging, down to recordings from single neurons. Ongoing cortical activity has been shown to play a critical role in development, and must also be essential for processing sensory perception, because it modulates stimulus-evoked activity, and is correlated with behaviour. Yet its role in the processing of external information and its relationship to internal representations of sensory attributes remains unknown. Using voltage sensitive dye imaging, we previously established a close link between ongoing activity in the visual cortex of anaesthetized cats and the spontaneous firing of a single neuron. Here we report that such activity encompasses a set of dynamically switching cortical states, many of which correspond closely to orientation maps. When such an orientation state emerged spontaneously, it spanned several hypercolumns and was often followed by a state corresponding to a proximal orientation. We suggest that dynamically switching cortical states could represent the brain's internal context, and therefore reflect or influence memory, perception and behaviour.

  5. The spontaneous market order and evolution.

    Science.gov (United States)

    Beck, Naomi

    2016-08-01

    Darwin's theory of natural selection and the idea of a spontaneous order share a fundamental feature: the claim that apparent design or order do not necessarily imply a designer or rational planning. But they also present important differences, which touch upon central questions such as the evolution of morality, the role of human agency in social evolution, the existence (or not) of directionality in undesigned processes, and the presence (nor not) of a providential element in evolutionary accounts. In this article, I explore these themes and probe the relationship between the notion of a spontaneous order and the theory of evolution by natural selection. The reflections of Nobel laureate in economics, F.A. von Hayek, provide the beginning and endpoint in this voyage, for they constitute the most pronounced effort to develop a full-fledged theory combining evolution and economics in recent times. But along the way, I also investigate the influence of classical political economy on Darwin's thought, primarily that of Adam Smith, and consider the reasons for which Darwin did not refer to Smith when discussing the principle of natural selection in The Origin of Species. I conclude that the spontaneous order, as understood by Hayek, and evolution by natural selection constitute two disparate concepts. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Perfect mixing of immiscible macromolecules at fluid interfaces

    Science.gov (United States)

    Sheiko, Sergei; Matyjaszewski, Krzysztof; Tsukruk, Vladimir; Carrillo, Jan-Michael; Rubinstein, Michael; Dobrynin, Andrey; Zhou, Jing

    2014-03-01

    Macromolecules typically phase separate unless their shapes and chemical compositions are tailored to explicitly drive mixing. But now our research has shown that physical constraints can drive spontaneous mixing of chemically different species. We have obtained long-range 2D arrays of perfectly mixed macromolecules having a variety of molecular architectures and chemistries, including linear chains, block-copolymer stars, and bottlebrush copolymers with hydrophobic, hydrophilic, and lipophobic chemical compositions. This is achieved by entropy-driven enhancement of steric repulsion between macromolecules anchored on a substrate. By monitoring the kinetics of mixing, we have proved that molecular intercalation is an equilibrium state. The array spacing is controlled by the length of the brush side chains. This entropic templating strategy opens new ways for generating patterns on sub-100 nm length scales with potential application in lithography, directed self-assembly, and biomedical assays. Financial support from the National Science Foundation DMR-0906985, DMR-1004576, DMR-1122483, and DMR-0907515.

  7. MIXED AND MIXING SYSTEMS WORLDWIDE: A PREFACE

    Directory of Open Access Journals (Sweden)

    Seán Patrick Donlan

    2012-09-01

    Full Text Available This issue of the Potchefstroom Electronic Law Journal (South Africa sees thepublication of a selection of articles derived from the Third International Congress ofthe World Society of Mixed Jurisdiction Jurists (WSMJJ. That Congress was held atthe Hebrew University of Jerusalem, Israel in the summer of 2011. It reflected athriving Society consolidating its core scholarship on classical mixed jurisdictions(Israel, Louisiana, the Philippines, Puerto Rico, Quebec, Scotland, and South Africawhile reaching to new horizons (including Cyprus, Hong Kong and Macau, Malta,Nepal, etc. This publication reflects in microcosm the complexity of contemporaryscholarship on mixed and plural legal systems. This complexity is, of course, wellunderstoodby South African jurists whose system is derived both from the dominantEuropean traditions as well as from African customary systems, including both thosethat make up part of the official law of the state as well as those non-state norms thatcontinue to be important in the daily lives of many South Africans.

  8. European mixed forests

    DEFF Research Database (Denmark)

    Bravo-Oviedo, Andres; Pretzsch, Hans; Ammer, Christian

    2014-01-01

    Aim of study: We aim at (i) developing a reference definition of mixed forests in order to harmonize comparative research in mixed forests and (ii) review the research perspectives in mixed forests. Area of study: The definition is developed in Europe but can be tested worldwide. Material...... and Methods: Review of existent definitions of mixed forests based and literature review encompassing dynamics, management and economic valuation of mixed forests. Main results: A mixed forest is defined as a forest unit, excluding linear formations, where at least two tree species coexist at any...... developmental stage, sharing common resources (light, water, and/or soil nutrients). The presence of each of the component species is normally quantified as a proportion of the number of stems or of basal area, although volume, biomass or canopy cover as well as proportions by occupied stand area may be used...

  9. Utterance independent bimodal emotion recognition in spontaneous communication

    Science.gov (United States)

    Tao, Jianhua; Pan, Shifeng; Yang, Minghao; Li, Ya; Mu, Kaihui; Che, Jianfeng

    2011-12-01

    Emotion expressions sometimes are mixed with the utterance expression in spontaneous face-to-face communication, which makes difficulties for emotion recognition. This article introduces the methods of reducing the utterance influences in visual parameters for the audio-visual-based emotion recognition. The audio and visual channels are first combined under a Multistream Hidden Markov Model (MHMM). Then, the utterance reduction is finished by finding the residual between the real visual parameters and the outputs of the utterance related visual parameters. This article introduces the Fused Hidden Markov Model Inversion method which is trained in the neutral expressed audio-visual corpus to solve the problem. To reduce the computing complexity the inversion model is further simplified to a Gaussian Mixture Model (GMM) mapping. Compared with traditional bimodal emotion recognition methods (e.g., SVM, CART, Boosting), the utterance reduction method can give better results of emotion recognition. The experiments also show the effectiveness of our emotion recognition system when it was used in a live environment.

  10. Innervation by a GABAergic neuron depresses spontaneous release in glutamatergic neurons and unveils the clamping phenotype of synaptotagmin-1

    DEFF Research Database (Denmark)

    Wierda, Keimpe D B; Sørensen, Jakob Balslev

    2014-01-01

    The role of spontaneously occurring release events in glutamatergic and GABAergic neurons and their regulation is intensely debated. To study the interdependence of glutamatergic and GABAergic spontaneous release, we compared reciprocally connected "mixed" glutamatergic/GABAergic neuronal pairs...... from mice cultured on astrocyte islands with "homotypic" glutamatergic or GABAergic pairs and autaptic neurons. We measured mEPSC and mIPSC frequencies simultaneously from both neurons. Neuronal pairs formed both interneuronal synaptic and autaptic connections indiscriminately. We find that whereas m......EPSC and mIPSC frequencies did not deviate between autaptic and synaptic connections, the frequency of mEPSCs in mixed pairs was strongly depressed compared with either autaptic neurons or glutamatergic pairs. Simultaneous imaging of synapses, or comparison to evoked release amplitudes, showed...

  11. Mixing of solids in different mixing devices

    Indian Academy of Sciences (India)

    Agitation of the powder (especially powders with different bulk densities) may result in migration of smaller particles downwards and of larger ones upwards. Another problem is segregation whose main cause is the difference in particle size, density shape and resilience. There are standard mixing devices, such as drum ...

  12. Spontaneous site reorientation in a mixed molecular crystal : Tetracene in benzoic acid

    NARCIS (Netherlands)

    LEVINSKY, HB; WIERSMA, DA

    1983-01-01

    Absorption and fluorescence spectra of tetracene in a benzoic acid host crystal at 1.5 K are presented. The fluorescence zero-phonon line is shifted by more than 800 cm–1 to the red of the maximum of the 120 cm–1 broad absorption origin. This shift is attributed to a lateral site reorientation of

  13. Ultrafast spontaneous emission modulation of graphene quantum dots interacting with Ag nanoparticles in solution

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jianwei [Department of Physics, Shanghai University, Shanghai 200444 (China); Research Center of Quantum Macro-Phenomenon and Application, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210 (China); Lu, Jian, E-mail: luj@sari.ac.cn; Wang, Zhongyang, E-mail: wangzy@sari.ac.cn [Research Center of Quantum Macro-Phenomenon and Application, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210 (China); Wang, Liang [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Institute of Nanochemistry and Nanobiology, Shanghai University, Shanghai 200444 (China); Tian, Linfan [Research Center of Quantum Macro-Phenomenon and Application, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210 (China); School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210 (China); Deng, Xingxia [Research Center of Quantum Macro-Phenomenon and Application, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210 (China); School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Tian, Lijun [Department of Physics, Shanghai University, Shanghai 200444 (China); Pan, Dengyu [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China)

    2016-07-11

    We investigated the strong interaction between graphene quantum dots and silver nanoparticles in solution using time-resolved photoluminescence techniques. In solution, the silver nanoparticles are surrounded by graphene quantum dots and interacted with graphene quantum dots through exciton-plasmon coupling. An ultrafast spontaneous emission process (lifetime 27 ps) was observed in such a mixed solution. This ultrafast lifetime corresponds to the emission rate exceeding 35 GHz, with the purcell enhancement by a factor of ∼12. These experiment results pave the way for the realization of future high speed light sources applications.

  14. SPONTANEOUS POTENTIAL INVESTIGATIONS IN SEMENIC MOUNTAINS

    Directory of Open Access Journals (Sweden)

    P. URDEA

    2014-11-01

    Full Text Available Spontaneous Potential Investigations in Semenic Mountains. The use of geophysical methods such as that of Spontaneous Potential (SP to investigate areas where the geomorphological processes occur, has the role to identify less visible processes as for example subcutaneous erosion or piping, subsoil water drainage and finding specific spatial differences of these processes. Comparative study of these sites allows correlation between geomorphological factors, soil and climate, but also to observe the evolution of subsurface erosion or underground water infiltration over time. During this investigation a series of mesh grids have been made in areas with different characteristics (lithology, pedology, slope, exposition, etc. at different time periods in order to spot and analyse the change in data in the chosen sites, various conditions given. Values expressed in millivolts (mV obtained by the Spontaneous Potential method have been put into an algorithm for interpolation looking to yield a pattern of values of what is happening in the soil during that period of time. Thus, in the autumn, the investigation site at the nivation niche Baia Vulturilor, returned values of between -22.6 mV and 65.6 mV, while in spring in the same site, values were within the range of -14.4 mV / 30.1 mV. On the other hand, on the site of the cryopediment under the Semenic peak, in the spring, return values ranged from -40.4 mV and -1.1 mV. A particular case is that of the glacis near Piatra Goznei peak; in this area anthropogenic electricity influences on soil can be found. Based on some models a trend of water movement in the soil could be established, this depending heavily on the amount of precipitation infiltration, local lithology, depth of soil and their structure, and evapotranspiration process. Water movement in the soil may be a correlation with sediment movement in soil horizons and instability manifested on the slopes.

  15. Fetal primary hydrothorax with spontaneous resolution

    Directory of Open Access Journals (Sweden)

    Vera Trocado

    2017-07-01

    Full Text Available Fetal primary hydrothorax is a rare congenital anomaly with an estimated incidence of 1:10.000–15.000 pregnancies, with an unpredictable clinical course, ranging from spontaneous resolution to fetal death. We present a case of a unilateral fetal pleural effusion identified at 35th gestational week. A 37 year-old woman (G2P1 presented to our routine term pregnancy evaluation. The pregnancy had been otherwise uneventful. At ecographic evaluation a large anechogenic fluid collection was identified in the right fetal hemithorax, with atelectasis of right lung, displacing the heart and mediastinal structures to the contralateral hemithorax. Hydramnios was also identified. No other structural abnormalities were detected, as no signs of hydrops. Fetal biometry was compatible with gestational age. Fetal ecochardiogram was structurally and functionally normal. Doppler evaluation of the peak systolic velocity in the middle cerebral artery was normal. Screening for congenital infections was negative. Complete blood cell count, blood type and antibody screening rulled-out immune hydrops. Karyotype analysis was not performed as family decision. Serial ecographic re-evaluations showed a progressive volume decrease and at the 38th week there was total resolution of the effusion. A C-section was performed at the 39th week. A live female infant was born weighing 3205 g, with no need of ventilatory support. One year post-partum follow-up evaluation confirmed the child was healthy. Spontaneous regression has been reported to occur in 9–22% of primary fetal hydrothoraxes, but the features predicting a better prognosis remain difficult to define. Unilateral effusion, spontaneous resolution and absence of hydrops at the age of diagnosis seem to be indicators of better outcome.

  16. A neurodynamic account of spontaneous behaviour.

    Science.gov (United States)

    Namikawa, Jun; Nishimoto, Ryunosuke; Tani, Jun

    2011-10-01

    The current article suggests that deterministic chaos self-organized in cortical dynamics could be responsible for the generation of spontaneous action sequences. Recently, various psychological observations have suggested that humans and primates can learn to extract statistical structures hidden in perceptual sequences experienced during active environmental interactions. Although it has been suggested that such statistical structures involve chunking or compositional primitives, their neuronal implementations in brains have not yet been clarified. Therefore, to reconstruct the phenomena, synthetic neuro-robotics experiments were conducted by using a neural network model, which is characterized by a generative model with intentional states and its multiple timescales dynamics. The experimental results showed that the robot successfully learned to imitate tutored behavioral sequence patterns by extracting the underlying transition probability among primitive actions. An analysis revealed that a set of primitive action patterns was embedded in the fast dynamics part, and the chaotic dynamics of spontaneously sequencing these action primitive patterns was structured in the slow dynamics part, provided that the timescale was adequately set for each part. It was also shown that self-organization of this type of functional hierarchy ensured robust action generation by the robot in its interactions with a noisy environment. This article discusses the correspondence of the synthetic experiments with the known hierarchy of the prefrontal cortex, the supplementary motor area, and the primary motor cortex for action generation. We speculate that deterministic dynamical structures organized in the prefrontal cortex could be essential because they can account for the generation of both intentional behaviors of fixed action sequences and spontaneous behaviors of pseudo-stochastic action sequences by the same mechanism.

  17. A neurodynamic account of spontaneous behaviour.

    Directory of Open Access Journals (Sweden)

    Jun Namikawa

    2011-10-01

    Full Text Available The current article suggests that deterministic chaos self-organized in cortical dynamics could be responsible for the generation of spontaneous action sequences. Recently, various psychological observations have suggested that humans and primates can learn to extract statistical structures hidden in perceptual sequences experienced during active environmental interactions. Although it has been suggested that such statistical structures involve chunking or compositional primitives, their neuronal implementations in brains have not yet been clarified. Therefore, to reconstruct the phenomena, synthetic neuro-robotics experiments were conducted by using a neural network model, which is characterized by a generative model with intentional states and its multiple timescales dynamics. The experimental results showed that the robot successfully learned to imitate tutored behavioral sequence patterns by extracting the underlying transition probability among primitive actions. An analysis revealed that a set of primitive action patterns was embedded in the fast dynamics part, and the chaotic dynamics of spontaneously sequencing these action primitive patterns was structured in the slow dynamics part, provided that the timescale was adequately set for each part. It was also shown that self-organization of this type of functional hierarchy ensured robust action generation by the robot in its interactions with a noisy environment. This article discusses the correspondence of the synthetic experiments with the known hierarchy of the prefrontal cortex, the supplementary motor area, and the primary motor cortex for action generation. We speculate that deterministic dynamical structures organized in the prefrontal cortex could be essential because they can account for the generation of both intentional behaviors of fixed action sequences and spontaneous behaviors of pseudo-stochastic action sequences by the same mechanism.

  18. Being Spontaneous: The Future of Telehealth Implementation?

    Science.gov (United States)

    Mars, Maurice; Scott, Richard E

    2017-09-01

    The smartphone simplifies interprofessional communication, and smartphone applications can facilitate telemedicine activity. Much has been written about the steps that need to be followed to implement and establish a successful telemedicine service that is integrated into everyday clinical practice. A traditional and systematic approach has evolved incorporating activities such as strategy development, needs assessment, business cases and plans, readiness assessment, implementation plans, change management interventions, and ongoing monitoring and evaluation. This "best practice" has been promoted in the telehealth literature for many years. In contrast, several recent initiatives have arisen without any such formal undertakings. This article describes the strengths and weaknesses of two "spontaneous" telemedicine services in dermatology and burn management that have evolved in South Africa. Two spontaneous services were identified and reviewed. In one unsolicited service, doctors at rural referring hospitals have been taking photographs of skin lesions and sending them with a brief text message history to dermatologists using the instant messaging smartphone app, WhatsApp. In the other, burns service, admissions to the burns unit or the clinic were triaged by telephonic description of the case and completion of a preadmission questionnaire. More recently, management and referral decisions are made only after completion of the questionnaire and subsequent submission of photographs of the burn sent by WhatsApp, with the decision transmitted by text message. Although efficient and effective, potential legal and ethical shortcomings have been identified. These "spontaneous" telehealth services challenge traditional best practice, yet appear to lead to truly integrated practice and, therefore, are successful and warrant further study.

  19. [The cell number in spontaneous uncentrifuged urine].

    Science.gov (United States)

    Rebentisch, G; Braun, H; Muche, J

    1982-08-01

    The leucocytes and erythrocytes in spontaneous urines were determined in the counting chamber at native and experimentally reduced pH values after standing for various periods. The pH value remained constant for up 6 h, whereby the disintegration of cells increases with rising pH values. The investigations do not rule out a circadian rhythm of cell excretion referring to the quantity of cells/time. Depending on the absolute number of cells the methodic variation coefficient lies between 4 and 25%.

  20. Angyomatous vocal polypus: a complete spontaneous regression

    Directory of Open Access Journals (Sweden)

    Edmir Américo Lourenço

    Full Text Available The authors describe a male patient who had malignant lymphoma seven years ago which remitted with chemotherapy.Two years ago he developed dysphonia. An unilateral, pediculate smooth red lesion on the right vocal fold was later discovered. Even without benefit of medicamentosus treatment, the patient refused surgery. In a reevaluation using rigid telescopy of the larynx two years later, the lesion had disappeared, completely and spontaneously. As there are no existing publications on this topic, this case report is an alert that surgery should be recommended with extreme caution in this type of vocal disease.

  1. Recurring spontaneous pneumothorax concomitant with menstruation

    Science.gov (United States)

    Davies, Rosemary

    1968-01-01

    Details are given of nine cases of recurrent spontaneous pneumothorax concomitant with menstruation; of these, four are culled from the literature. In every case the time interval between the onset of menstruation and the development of a pneumothorax has been very close, and from the evidence presented some causal relationship is envisaged. Endometriosis is considered as a possible cause. Two of the patients had proven endometriosis of the diaphragm and this condition was almost certainly present in a third patient. Three patients had pelvic endometriosis. The pneumothorax always occurred on the right side, and the possible significance of this is discussed. PMID:5664697

  2. Spontaneous Brillouin scattering in a microdroplet

    Science.gov (United States)

    Ching, S. C.; Leung, P. T.; Young, K.

    1990-05-01

    Spontaneous Brillouin scattering in a micrometer-sized liquid droplet is analyzed from first principles, using the spherical-wave normal-mode basis. Instead of the conservation of linear momentum, this interaction is governed by a selection rule due to the conservation of angular momentum. The Brillouin spectrum is then calculated, both for observation at a given angle and for the sum over all angles, and compared with scattering in a bulk medium. Special attention is paid to the case where the incident and scattered radiation fall on an electromagnetic resonance of the droplet. The analysis lays the foundation for formulating stimulated Brillouin scattering in the same system.

  3. Promoting Spontaneous Second Harmonic Generation through Organogelation.

    Science.gov (United States)

    Marco, A Belén; Aparicio, Fátima; Faour, Lara; Iliopoulos, Konstantinos; Morille, Yohann; Allain, Magali; Franco, Santiago; Andreu, Raquel; Sahraoui, Bouchta; Gindre, Denis; Canevet, David; Sallé, Marc

    2016-07-27

    An organogelator based on the Disperse Red nonlinear optical chromophore was synthesized according to a simple and efficient three-step procedure. The supramolecular gel organization leads to xerogels which display a spontaneous second harmonic generation (SHG) response without any need for preprocessing, and this SHG activity appears to be stable over several months. These findings, based on an intrinsic structural approach, are supported by favorable intermolecular supramolecular interactions, which promote a locally non-centrosymmetric NLO-active organization. This is in sharp contrast with most materials designed for SHG purposes, which generally require the use of expensive or heavy-to-handle external techniques for managing the dipoles' alignment.

  4. Spontaneous Achilles tendon rupture in alkaptonuria

    Science.gov (United States)

    Alajoulin, Omar A.; Alsbou, Mohammed S.; Ja’afreh, Somayya O.; Kalbouneh, Heba M.

    2015-01-01

    Alkaptonuria (AKU) is a rare inborn metabolic disease characterized by accumulation of homogentisic acid (HGA). Excretion of HGA in urine causes darkening of urine and its deposition in connective tissues causes dark pigmentation (ochronosis), early degeneration of articular cartilage, weakening of the tendons, and subsequent rupture. In this case report, we present a rare case of a patient presented with unilateral spontaneous rupture of Achilles tendon due to AKU. The patient developed most of the orthopedic manifestations of the disease earlier than typical presentations. Alkaptonuria patients should avoid strenuous exercises and foot straining especially in patients developing early orthopedic manifestations. PMID:26620992

  5. Spontaneous electric fields in solid films: spontelectrics

    DEFF Research Database (Denmark)

    Field, David; Plekan, Oksana; Cassidy, Andrew

    2013-01-01

    When dipolar gases are condensed at sufficiently low temperature onto a solid surface, they form films that may spontaneously exhibit electric fields in excess of 108V/m. This effect, called the ‘spontelectric effect’, was recently revealed using an instrument designed to measure scattering...... and capture of low energy electrons by molecular films. In this review it is described how this discovery was made and the properties of materials that display the spontelectric effect, so-called ‘spontelectrics’, are set out. A discussion is included of properties that differentiate spontelectrics from...

  6. Spontaneous hygroma in intracranial arachnoid cyst

    Energy Technology Data Exchange (ETDEWEB)

    Agnoli, A.L.

    1984-06-01

    Anamnesis and treatment of two cases of arachnoid cysts extending into the subarachnoid space are described. No traumatic incident was discovered in the previous history of these two patients. The causal genesis of neurological signs of deficiency in patients with arachnoid and acquired cysts is discussed. However, the cause of the development of a subdural hygroma in arachnoid cysts remains unclarified. CT findings of arachnoid cysts with a hypodense zone between brain surface and the vault of the cranium always require an investigation into the possibility of a spontaneous emptying of the cyst or of a congenital and not only localised extension of the cyst itself.

  7. NSAIDs and spontaneous abortions - true effect or an indication bias?

    Science.gov (United States)

    Daniel, Sharon; Koren, Gideon; Lunenfeld, Eitan; Levy, Amalia

    2015-10-01

    The aim of the study was to characterize the extent of indication bias resulting from the excessive use of NSAIDs on the days preceding a spontaneous abortion to relieve pain. We used data from a retrospective cohort study assessing the risk for spontaneous abortions following exposure to NSAIDs. Three definitions of exposure for cases of spontaneous abortions were compared, from the first day of pregnancy until the day of spontaneous abortion and until 3 and 2 days before a spontaneous abortion. Statistical analysis was performed using multivariate time programmed Cox regression. A sharp increase was observed in the dispensation of indomethacin, diclofenac and naproxen, and a milder increase was found in the use of ibuprofen during the week before a spontaneous abortion. Non- selective COX inhibitors in general and specifically diclofenac and indomethacin were found to be associated with spontaneous abortions when the exposure period was defined until the day of spontaneous abortion (hazard ratio (HR) 1.15, 95% confidence interval (CI) 1.04, 1.28; HR 1.31, 95% CI 1.08, 1.59 and HR 3.33, 95% CI 2.09, 5.29, respectively). The effect disappears by excluding exposures occurring on the day before the spontaneous abortion for non-selective COX inhibitors and on the last week before the spontaneous abortion for indomethacin. In general, decreasing HRs were found with the exclusion of exposures occurring on the days immediately before the spontaneous abortion. The increased use of NSAIDs during the last few days that preceded a spontaneous abortion to relieve pain associated with the miscarriage could bias studies assessing the association between exposure to NSAIDs and spontaneous abortions. © 2015 The British Pharmacological Society.

  8. The Mixed language Debate

    DEFF Research Database (Denmark)

    A range of views on mixed languages and their connections to phenomena such as secret languages, massive borrowing, codeswitching and codemixing, and thier origin.......A range of views on mixed languages and their connections to phenomena such as secret languages, massive borrowing, codeswitching and codemixing, and thier origin....

  9. System equivalent model mixing

    NARCIS (Netherlands)

    Klaassen, Steven W.B.; van der Seijs, M.V.; de Klerk, D.

    2017-01-01

    This paper introduces SEMM: a method based on Frequency Based Substructuring (FBS) techniques that enables the construction of hybrid dynamic models. With System Equivalent Model Mixing (SEMM) frequency based models, either of numerical or experimental nature, can be mixed to form a hybrid model.

  10. High-mix insulins

    Directory of Open Access Journals (Sweden)

    Sanjay Kalra

    2015-01-01

    Full Text Available Premix insulins are commonly used insulin preparations, which are available in varying ratios of different molecules. These drugs contain one short- or rapid-acting, and one intermediate- or long-acting insulin. High-mix insulins are mixtures of insulins that contain 50% or more than 50% of short-acting insulin. This review describes the clinical pharmacology of high-mix insulins, including data from randomized controlled trials. It suggests various ways, in which high-mix insulin can be used, including once daily, twice daily, thrice daily, hetero-mix, and reverse regimes. The authors provide a rational framework to help diabetes care professionals, identify indications for pragmatic high-mix use.

  11. Progesterone to prevent spontaneous preterm birth

    Science.gov (United States)

    Romero, Roberto; Yeo, Lami; Chaemsaithong, Piya; Chaiworapongsa, Tinnakorn; Hassan, Sonia

    2014-01-01

    Summary Preterm birth is the leading cause of perinatal morbidity and mortality worldwide, and its prevention is an important healthcare priority. Preterm parturition is one of the ‘great obstetrical syndromes’ and is caused by multiple etiologies. One of the mechanisms of disease is the untimely decline in progesterone action, which can be manifested by a sonographic short cervix in the midtrimester. The detection of a short cervix in the midtrimester is a powerful risk factor for preterm delivery. Vaginal progesterone can reduce the rate of preterm delivery by 45%, and the rate of neonatal morbidity (admission to neonatal intensive care unit, respiratory distress syndrome, need for mechanical ventilation, etc.). To prevent one case of spontaneous preterm birth preterm birth in women with a short cervix both with and without a prior history of preterm birth. In patients with a prior history of preterm birth, vaginal progesterone is as effective as cervical cerclage to prevent preterm delivery. 17α-Hydroxyprogesterone caproate has not been shown to be effective in reducing the rate of spontaneous preterm birth in women with a short cervix. PMID:24315687

  12. Spontaneous ad hoc mobile cloud computing network.

    Science.gov (United States)

    Lacuesta, Raquel; Lloret, Jaime; Sendra, Sandra; Peñalver, Lourdes

    2014-01-01

    Cloud computing helps users and companies to share computing resources instead of having local servers or personal devices to handle the applications. Smart devices are becoming one of the main information processing devices. Their computing features are reaching levels that let them create a mobile cloud computing network. But sometimes they are not able to create it and collaborate actively in the cloud because it is difficult for them to build easily a spontaneous network and configure its parameters. For this reason, in this paper, we are going to present the design and deployment of a spontaneous ad hoc mobile cloud computing network. In order to perform it, we have developed a trusted algorithm that is able to manage the activity of the nodes when they join and leave the network. The paper shows the network procedures and classes that have been designed. Our simulation results using Castalia show that our proposal presents a good efficiency and network performance even by using high number of nodes.

  13. [Spontaneous achilles tendon rupture in granulomatous vasculitis].

    Science.gov (United States)

    Benthien, Jan Philipp; Delling, G; Rüther, W

    2003-08-01

    A 66-year old patient sustained a non-traumatic rupture of her left achilles tendon. She suffered from Sjögren's syndrome which occurred in conjunction with a systemic vasculitis, and recurrent episcleritis. The combination of Sjögren's syndrome and systemic vasculitis is well known. Subsequently, she was treated with high-dose systemic steroids over a period of 2 years. In order to reduce the amount of steroids due to preexisting severe osteoporosis and thoracic vertebral fractures, her medication was changed to cyclophosphamide shortly before her injury. Intraoperatively, a granuloma was discovered at the site of the rupture. This granuloma had infiltrated most of the achilles tendon at this site and virtually replaced viable tendon tissue. Originally, the rupture was supposedly due to the high dose steroids. This theory had to be revised according to the intraoperative findings. Following excision of the granuloma and operative treatment of the achilles tendon rupture, the continuity of the tendon could be completely restored. A MRI scan 3 months after the procedure demonstrated a completely healed Achilles tendon. Spontaneous achilles tendon rupture due to a granuloma in patients with vasculitis seems to be a rare event. However, tendon ruptures in combination with systemic lupus erythematodes have been described. Mostly, these events are attributed to long term application of steroids. Spontaneous rupture in combination with high dose treatment of steroids seems to be an underestimated problem.

  14. Body Mass Index and spontaneous miscarriage.

    LENUS (Irish Health Repository)

    Turner, Michael J

    2012-02-01

    OBJECTIVE: We compared the incidence of spontaneous miscarriage in women categorised as obese, based on a Body Mass Index (BMI) >29.9 kg\\/m(2), with women in other BMI categories. STUDY DESIGN: In a prospective observational study conducted in a university teaching hospital, women were enrolled at their convenience in the first trimester after a sonogram confirmed an ongoing singleton pregnancy with fetal heart activity present. Maternal height and weight were measured digitally and BMI calculated. Maternal body composition was measured by advanced bioelectrical impedance analysis. RESULTS: In 1200 women, the overall miscarriage rate was 2.8% (n=33). The mean gestational age at enrolment was 9.9 weeks. In the obese category (n=217), the miscarriage rate was 2.3% compared with 3.3% in the overweight category (n=329), and 2.3% in the normal BMI group (n=621). There was no difference in the mean body composition parameters, particularly fat mass parameters, between those women who miscarried and those who did not. CONCLUSIONS: In women with sonographic evidence of fetal heart activity in the first trimester, the rate of spontaneous miscarriage is low and is not increased in women with BMI>29.9 kg\\/m(2) compared to women in the normal BMI category.

  15. Spontaneous delivery is related to barometric pressure.

    Science.gov (United States)

    Akutagawa, Osamu; Nishi, Hirotaka; Isaka, Keiichi

    2007-04-01

    Many studies have shown that changes in the weather affect health. In the field of obstetrics and gynecology, several events have been empirically shown to be related to the weather. Labor pain is controlled by the autonomic nervous system and various hormones, and is expected to be influenced by the weather and environmental changes. Several studies have been conducted on the relationship between delivery and barometric pressure, which shows constant changes with changes in weather, but there is no generally accepted view on this. We conducted a retrospective study in our patients who had a spontaneous cephalic delivery in this hospital between January 1997 and December 2003, in order to determine whether low barometric pressure induces labor pains, premature rupture of the membranes, and delivery, and whether changes in barometric pressure affect delivery. There was a significant increase in the number of deliveries and rupture of the membranes at low barometric pressure (P barometric pressure. This tendency was noted in both women with spontaneous rupture of the fetal membranes and those with premature rupture of the membranes (P barometric pressure, regardless of whether it was increasing or decreasing, the number of deliveries increased and the relationship was statistically significant (P barometric pressure, suggesting that low barometric pressure induces rupture of the fetal membranes and delivery.

  16. Spontaneous Ad Hoc Mobile Cloud Computing Network

    Directory of Open Access Journals (Sweden)

    Raquel Lacuesta

    2014-01-01

    Full Text Available Cloud computing helps users and companies to share computing resources instead of having local servers or personal devices to handle the applications. Smart devices are becoming one of the main information processing devices. Their computing features are reaching levels that let them create a mobile cloud computing network. But sometimes they are not able to create it and collaborate actively in the cloud because it is difficult for them to build easily a spontaneous network and configure its parameters. For this reason, in this paper, we are going to present the design and deployment of a spontaneous ad hoc mobile cloud computing network. In order to perform it, we have developed a trusted algorithm that is able to manage the activity of the nodes when they join and leave the network. The paper shows the network procedures and classes that have been designed. Our simulation results using Castalia show that our proposal presents a good efficiency and network performance even by using high number of nodes.

  17. [Spontaneous remission of congenital leukemia cutis].

    Science.gov (United States)

    Eberst, E; Michel, B; Stoebner, P; Dandurand, M; Meunier, L

    2011-01-01

    Aleukaemic leukaemia--without blasts in the blood or the bone marrow--with isolated cutaneous manifestations has been very rarely reported since only seven patients have been described to date. The prognosis is variable, and the indications for an aggressive treatment such as polychemotherapy are currently unclear. We report a case of spontaneously remitting aleukaemic leukaemia in a newborn child and compare it with other cases in the literature. A male newborn presented diffuse, violaceous skin nodules reminiscent of the so-called "blueberry muffin syndrome" present since birth. Blood and marrow examinations did not show any blasts and karyotype was normal. Biopsy of a nodule established the diagnosis of acute myeloid leukaemia type 5. The course was spontaneously favourable despite the absence of specific therapy and the boy was asymptomatic after one year of follow-up. Of the eight reported infants (including ours), three died, including two through acute transformation of the leukaemia. The prognosis seems to be highly dependent on cytogenetic features with the 11q23 rearrangement being at higher risk of acute transformation, prompting recourse to aggressive chemotherapy. Our case further illustrates the favourable prognostic value of a normal karyotype, a situation in which therapeutic abstention seems possible, and is even recommended. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  18. Controlling collective spontaneous emission with plasmonic waveguides.

    Science.gov (United States)

    Li, Ying; Argyropoulos, Christos

    2016-11-14

    We demonstrate a plasmonic route to control the collective spontaneous emission of two-level quantum emitters. Superradiance and subradiance effects are observed over distances comparable to the operating wavelength inside plasmonic nanochannels. These plasmonic waveguides can provide an effective epsilon-near-zero operation in their cut-off frequency and Fabry-Pérot resonances at higher frequencies. The related plasmonic resonant modes are found to efficiently enhance the constructive (superradiance) or destructive (subradiance) interference between different quantum emitters located inside the waveguides. By increasing the number of emitters located in the elongated plasmonic channel, the superradiance effect is enhanced at the epsilon-near-zero operation, leading to a strong coherent increase in the collective spontaneous emission rate. In addition, the separation distance between neighboring emitters and their emission wavelengths can be changed to dynamically control the collective emission properties of the plasmonic system. It is envisioned that the dynamic modification between quantum superradiant and subradiant modes will find applications in quantum entanglement of qubits, low-threshold nanolasers and efficient sensors.

  19. Spontaneous avalanche dephasing in large Rydberg ensembles

    Science.gov (United States)

    Boulier, T.; Magnan, E.; Bracamontes, C.; Maslek, J.; Goldschmidt, E. A.; Young, J. T.; Gorshkov, A. V.; Rolston, S. L.; Porto, J. V.

    2017-11-01

    Strong dipole-exchange interactions due to spontaneously produced contaminant states can trigger rapid dephasing in many-body Rydberg ensembles [E. A. Goldschmidt et al., Phys. Rev. Lett. 116, 113001 (2016), 10.1103/PhysRevLett.116.113001]. Such broadening has serious implications for many proposals to coherently use Rydberg interactions, particularly Rydberg dressing proposals. The dephasing arises as a runaway process where the production of the first contaminant atoms facilitates the creation of more contaminant atoms. Here we study the time dependence of this process with stroboscopic approaches. Using a pump-probe technique, we create an excess "pump" Rydberg population and probe its effect with a different "probe" Rydberg transition. We observe a reduced resonant pumping rate and an enhancement of the excitation on both sides of the transition as atoms are added to the pump state. We also observe a time scale for population growth that is significantly shorter than predicted by homogeneous mean-field models, as expected from a clustered growth mechanism where high-order correlations dominate the dynamics. These results support earlier works and confirm that the time scale for the onset of dephasing is reduced by a factor which scales as the inverse of the atom number. In addition, we discuss several approaches to minimize these effects of spontaneous broadening, including stroboscopic techniques and operating at cryogenic temperatures. It is challenging to avoid the unwanted broadening effects, but under some conditions they can be mitigated.

  20. ADVANCED MIXING MODELS

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S; Richard Dimenna, R; David Tamburello, D

    2008-11-13

    The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank with one to four dual-nozzle jet mixers located within the tank. The typical criteria to establish a mixed condition in a tank are based on the number of pumps in operation and the time duration of operation. To ensure that a mixed condition is achieved, operating times are set conservatively long. This approach results in high operational costs because of the long mixing times and high maintenance and repair costs for the same reason. A significant reduction in both of these costs might be realized by reducing the required mixing time based on calculating a reliable indicator of mixing with a suitably validated computer code. The work described in this report establishes the basis for further development of the theory leading to the identified mixing indicators, the benchmark analyses demonstrating their consistency with widely accepted correlations, and the application of those indicators to SRS waste tanks to provide a better, physically based estimate of the required mixing time. Waste storage tanks at SRS contain settled sludge which varies in height from zero to 10 ft. The sludge has been characterized and modeled as micron-sized solids, typically 1 to 5 microns, at weight fractions as high as 20 to 30 wt%, specific gravities to 1.4, and viscosities up to 64 cp during motion. The sludge is suspended and mixed through the use of submersible slurry jet pumps. To suspend settled sludge, water is added to the tank as a slurry medium and stirred with the jet pump. Although there is considerable technical literature on mixing and solid suspension in agitated tanks, very little literature has been published on jet mixing in a large-scale tank. If shorter mixing times can be shown to support Defense Waste Processing Facility (DWPF) or other feed requirements, longer pump lifetimes can be achieved with associated operational cost and

  1. Maternal smoking predicts the risk of spontaneous abortion

    DEFF Research Database (Denmark)

    Nielsen, Ann; Hannibal, Charlotte Gerd; Lindekilde, Bodil Eriksen

    2006-01-01

    BACKGROUND: Few studies have examined smoking prior to pregnancy and the occurrence of spontaneous abortion, as most studies have addressed the risk of spontaneous abortion in relation to smoking during pregnancy. However, results are not entirely consistent. The aim of the present study...... was to assess the risk of spontaneous abortion considering smoking prior to pregnancy. METHODS: We performed a nested case-control study using prospective data from a population-based cohort comprising 11,088 women aged 20-29 years. From this cohort, women who experienced either a spontaneous abortion (n=343......) or who gave birth (n=1,578) during follow-up were selected. Associations between self-reported smoking at enrollment and subsequent spontaneous abortion were analyzed by means of multiple logistic regression. RESULTS: The risk of spontaneous abortion in relation to pre-pregnancy smoking showed a clear...

  2. Maternal underweight and the risk of spontaneous abortion

    DEFF Research Database (Denmark)

    Helgstrand, Stine; Andersen, Anne-Marie Nybo

    2005-01-01

    BACKGROUND: To evaluate the risk of spontaneous abortion in relation to maternal pre-pregnant underweight. METHODS: The study was designed as a cohort study within the framework of the Danish National Birth Cohort (DNBC). The participants were a total of 23 821 women recruited consecutively...... spontaneous abortion. Relative risk of spontaneous abortion was calculated as Hazard Ratios using Cox regression with delayed entry. RESULTS: The outcome measure was spontaneous abortion. The hazard ratio for spontaneous abortion in women with a pre-pregnant body mass index (BMI) below 18.5 was 1.24 (95......% confidence limits 0.95-1.63) compared to women with pre-pregnant BMI 18.5-24.9. Women with a BMI of 25 or more had a smaller increase in risk of spontaneous abortion. Adjustment for maternal age, parity, previous miscarriages, and lifestyle factors did not affect the estimates substantially, neither did...

  3. Impairments of spontaneous and deliberative mentalizing co-occur, yet dissociate, in schizophrenia.

    Science.gov (United States)

    Langdon, Robyn; Flynn, Michaela; Connaughton, Emily; Brüne, Martin

    2017-11-01

    Evidence of impairment in explicit mentalizing in people with schizophrenia has inspired interventions to improve awareness of others' mental states in these individuals. Less is known of implicit mentalizing in schizophrenia, with current findings mixed. We sought to resolve previous inconsistencies using Heider & Simmel's (H&S) classic animation to elicit spontaneous mentalizing and examined relations between spontaneous and deliberative mentalizing. Forty-five schizophrenia outpatients and 27 general-community controls completed two explicit theory-of-mind (TOM) tasks and then described the H&S animation (to elicit spontaneous social attributions about emotionally driven, as well as goal-driven, behaviours), before and after an instruction to think of the shapes as people. Accuracy of basic and social facts and frequencies of personification and different mental-state terms were recorded. Explicit TOM performance was impaired in patients. Patients also generated fewer social (but not basic) facts than controls to describe the H&S animation, and used less mental-state language, before, and even more so, after the 'people' instruction, despite that both groups had used more personification terms after the 'people' instruction. Measures of explicit and spontaneous mentalizing contributed independently to discriminating between groups. Patients respond less to the bottom-up signals of agency that ought normally to elicit spontaneous social attributions, even when cued to think of the stimuli as people, and the stimuli depict emotionally driven, as well as goal-driven, behaviour. That impairments of spontaneous and deliberative mentalizing dissociate in schizophrenia suggests that training deliberative mentalizing may not be enough; interventions to improve spontaneous mentalizing are also needed. Findings People with schizophrenia were less likely than controls to spontaneously attribute causal mental states when viewing dynamic signals of emotionally driven and

  4. Effects of Raman scattering and attenuation in silica fiber-based parametric frequency conversion

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Andersen, Lasse Mejling; Rottwitt, Karsten

    2017-01-01

    Four-wave mixing in the form of Bragg scattering (BS) has been predicted to enable quantum noise-less frequency conversion by analytic quantum approaches. Using a semi-classical description of quantum noise that accounts for loss and stimulated and spontaneous Raman scattering, which...

  5. Spontaneous Rupture of Pyometra Causing Peritonitis in Elderly Female Diagnosed on Dynamic Transvaginal Ultrasound

    Directory of Open Access Journals (Sweden)

    Sharad M. Malvadkar

    2016-01-01

    Full Text Available Pyometra is collection of pus within the uterine cavity and is usually associated with underlying gynaecological malignancy or other benign causes. Spontaneous rupture of pyometra is a rare complication. We report a case of a 65-year-old female who presented with acute abdomen and was diagnosed with a ruptured uterus secondary to pyometra and consequent peritonitis on dynamic transvaginal sonography (TVS which was later confirmed on contrast enhanced computed tomography (CECT. An emergency laparotomy was performed and about 800 cc of pus was drained from the peritoneal cavity. A rent was found in the anterior uterine wall and hence hysterectomy was performed. Histopathology revealed mixed inflammatory cell infiltrate with no evidence of malignancy. There are only 31 cases of ruptured pyometra reported till date, most of which were definitively diagnosed only on laparotomy. In only two of these cases the preoperative diagnosis was made on CECT. We report this case, as the correct and definitive diagnosis was made preoperatively on dynamic TVS. To our knowledge, this is the first case report revealing spontaneous ruptured pyometra being diagnosed preoperatively on dynamic TVS. This report is aimed at giving emphasis on the use of simple dynamic TVS for accurate diagnosis of rare spontaneous ruptured pyometra causing peritonitis.

  6. Spontaneous Uterine Perforation Caused by Pyometra: A Case Report

    OpenAIRE

    Yousefi, Zohreh; sharifi, Noorieh; Morshedy, Maryam

    2014-01-01

    Introduction: Pyometra is an accumulation of purulent material or pus in the uterine cavity. Spontaneous perforation of uterus by pyometra is rare. This is a clinical presentation and management of a spontaneous perforation of uterine caused by pyometra. Case Presentation: This is a case report on spontaneously perforated associated with pyometra secondary to cervical malignancy. The patient underwent exploratory laparotomy with total hysterectomy and bilateral salpingo-oophorectomy. Conclusi...

  7. Spontaneous globe luxation associated with chronic obstructive pulmonary disease

    Directory of Open Access Journals (Sweden)

    M Ashok Kumar

    2012-01-01

    Full Text Available Spontaneous globe luxation is a rarely reported condition which can lead to complications like optic neuropathy. Common causes are thyroid eye disease, shallow orbit and floppy eyelid syndrome. We report a case of spontaneous globe luxation with the onset and severity associated with chronic obstructive pulmonary disease (COPD. To our knowledge, this is the first case of spontaneous globe luxation associated with COPD.

  8. Multi-copy entanglement purification with practical spontaneous parametric down conversion sources

    Science.gov (United States)

    Zhang, Shuai-Shuai; Shu, Qi; Zhou, Lan; Sheng, Yu-Bo

    2017-06-01

    Entanglement purification is to distill the high quality entanglement from the low quality entanglement with local operations and classical communications. It is one of the key technologies in long-distance quantum communication. We discuss an entanglement purification protocol (EPP) with spontaneous parametric down conversion (SPDC) sources, in contrast to previous EPP with multi-copy mixed states, which requires ideal entanglement sources. We show that the SPDC source is not an obstacle for purification, but can benefit the fidelity of the purified mixed state. This EPP works for linear optics and is feasible in current experiment technology. Project supported by the National Natural Science Foundation of China (Grant Nos. 11474168 and 61401222), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20151502), the Qing Lan Project in Jiangsu Province, China, and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, China.

  9. Connecting nonzero θ 13, Dirac CP phase and leptogenesis through spontaneous CP violation

    Science.gov (United States)

    Karmakar, Biswajit; Sil, Arunansu

    2017-09-01

    We have analyzed a Type-I+II seesaw scenario to generate neutrino masses and mixing in a A 4 based flavor symmetric framework. The Standard Model (SM) particle content is extended by three singlet right handed neutrinos, an additional higgs triplet along with few SM singlet flavon fields. In this set-up, the pure type-I contribution to the neutrino mass matrix exhibits a tribimaximal (TBM) of lepton mixing where the triplet contribution generates θ 13. Complex vev of one flavon provides a unique source of spontaneous CP violation. Here it turns out that the triplet contribution provides a common source for θ 13, Dirac CP phase (δ) and CP violation required for leptogenesis.

  10. ADVANCED MIXING MODELS

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S; Dimenna, R; Tamburello, D

    2011-02-14

    The process of recovering and processing High Level Waste (HLW) the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank with one to four mixers (pumps) located within the tank. The typical criteria to establish a mixed condition in a tank are based on the number of pumps in operation and the time duration of operation. To ensure that a mixed condition is achieved, operating times are typically set conservatively long. This approach results in high operational costs because of the long mixing times and high maintenance and repair costs for the same reason. A significant reduction in both of these costs might be realized by reducing the required mixing time based on calculating a reliable indicator of mixing with a suitably validated computer code. The focus of the present work is to establish mixing criteria applicable to miscible fluids, with an ultimate goal of addressing waste processing in HLW tanks at SRS and quantifying the mixing time required to suspend sludge particles with the submersible jet pump. A single-phase computational fluid dynamics (CFD) approach was taken for the analysis of jet flow patterns with an emphasis on the velocity decay and the turbulent flow evolution for the farfield region from the pump. Literature results for a turbulent jet flow are reviewed, since the decay of the axial jet velocity and the evolution of the jet flow patterns are important phenomena affecting sludge suspension and mixing operations. The work described in this report suggests a basis for further development of the theory leading to the identified mixing indicators, with benchmark analyses demonstrating their consistency with widely accepted correlations. Although the indicators are somewhat generic in nature, they are applied to Savannah River Site (SRS) waste tanks to provide a better, physically based estimate of the required mixing time. Waste storage tanks at SRS contain settled sludge which varies in

  11. The mixing of fluids

    Energy Technology Data Exchange (ETDEWEB)

    Ottino, J.M.

    1989-01-01

    What do the eruption of Krakatau, the manufacture of puff pastry and the brightness of stars have in common Each involves some aspect of mixing. Mixing also plays a critical role in modern technology. Chemical engineers rely on mixing to ensure that substances react properly, to produce polymer blends that exhibit unique properties and to disperse drag-reducing agents in pipelines. Yet in spite of its of its ubiquity in nature and industry, mixing is only imperfectly under-stood. Indeed, investigators cannot even settle on a common terminology: mixing is often referred to as stirring by oceanographers and geophysicists, as blending by polymer engineers and as agitation by process engineers. Regardless of what the process is called, there is little doubt that it is exceedingly complex and is found in a great variety of systems. In constructing a theory of fluid mixing, for example, one has to take into account fluids that can be miscible or partially miscible and reactive or inert, and flows that are slow and orderly or very fast and turbulent. It is therefore not surprising that no single theory can explain all aspect of mixing in fluids and that straightforward computations usually fail to capture all the important details. Still, both physical experiments and computer simulations can provide insight into the mixing process. Over the past several years the authors and his colleague have taken both approaches in an effort to increase understanding of various aspect of the process-particularly of mixing involving slow flows and viscous fluids such as oils.

  12. Spontaneous regression of a lumbar disc herniation: case report

    Directory of Open Access Journals (Sweden)

    Mostarchid Brahim El

    2016-12-01

    Full Text Available Lumbar disc herniation is a common disease that induces back pain and radicular pain. Some cases require conservative treatment or at times relived spontaneously. Spontaneous regression of disc herniation is an atypical clinical presentation, and it has been recognized with the advancement of recent advances in imaging techniques. We present a 35-year-old woman presented a spontaneous regression of a lumbar disc herniation with good outcome after intensive physical therapy program. Spontaneous regression of disc herniation is thought to occur via an inflammatory reaction with molecular mechanisms of phagocytic processes.

  13. Dorsomedial prefontal cortex supports spontaneous thinking per se.

    Science.gov (United States)

    Raij, T T; Riekki, T J J

    2017-06-01

    Spontaneous thinking, an action to produce, consider, integrate, and reason through mental representations, is central to our daily experience and has been suggested to serve crucial adaptive purposes. Such thinking occurs among other experiences during mind wandering that is associated with activation of the default mode network among other brain circuitries. Whether and how such brain activation is linked to the experience of spontaneous thinking per se remains poorly known. We studied 51 healthy subjects using a comprehensive experience-sampling paradigm during 3T functional magnetic resonance imaging. In comparison with fixation, the experiences of spontaneous thinking and spontaneous perception were related to activation of wide-spread brain circuitries, including the cortical midline structures, the anterior cingulate cortex and the visual cortex. In direct comparison of the spontaneous thinking versus spontaneous perception, activation was observed in the anterior dorsomedial prefrontal cortex. Modality congruence of spontaneous-experience-related brain activation was suggested by several findings, including association of the lingual gyrus with visual in comparison with non-verbal-non-visual thinking. In the context of current literature, these findings suggest that the cortical midline structures are involved in the integrative core substrate of spontaneous thinking that is coupled with other brain systems depending on the characteristics of thinking. Furthermore, involvement of the anterior dorsomedial prefrontal cortex suggests the control of high-order abstract functions to characterize spontaneous thinking per se. Hum Brain Mapp 38:3277-3288, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  14. Visually evoked spiking evolves while spontaneous ongoing dynamics persist

    Directory of Open Access Journals (Sweden)

    Raoul eHuys

    2016-01-01

    Full Text Available Neurons in the primary visual cortex spontaneously spike even when there are no visual stimuli. It is unknown whether the spiking evoked by visual stimuli is just a modification of the spontaneous ongoing cortical spiking dynamics or whether the spontaneous spiking state disappears and is replaced by evoked spiking. This study of laminar recordings of spontaneous spiking and visually evoked spiking of neurons in the ferret primary visual cortex shows that the spiking dynamics does not change: the spontaneous spiking as well as evoked spiking is controlled by a stable and persisting fixed point attractor. Its existence guarantees that evoked spiking return to the spontaneous state. However, the spontaneous ongoing spiking state and the visual evoked spiking states are qualitatively different and are separated by a threshold (separatrix. The functional advantage of this organization is that it avoids the need for a system reorganization following visual stimulation, and impedes the transition of spontaneous spiking to evoked spiking and the propagation of spontaneous spiking from layer 4 to layers 2-3.

  15. Spontaneous closure of an ileostomy: A rare occurrence

    Directory of Open Access Journals (Sweden)

    Ashish Saxena

    2015-01-01

    CONCLUSION: Further research is warranted to understand the mechanism behind spontaneous regression of a stoma. Relationship between this event and intestinal tuberculosis or ATT needs to be analysed.

  16. General Anesthesia with Preserved Spontaneous Breathing through an Intubation Tube

    Directory of Open Access Journals (Sweden)

    V. V. Moroz

    2010-01-01

    Full Text Available Objective: to study whether spontaneous patient breathing may be preserved during elective operations under general anesthesia with tracheal intubation. Subjects and methods. One hundred and twelve patients undergoing elective surgeries under general endotracheal anesthesia were randomized into 2 groups: 1 patients who had forced mechanical ventilation in the volume-controlled mode and 2 those who received assisted ventilation as spontaneous breathing with mechanical support. Conclusion. The study shows that spontaneous breathing with mechanical support may be safely used during some surgical interventions in patients with baseline healthy lungs. Key words: Pressure Support, assisted ventilation, spontaneous breathing, general anesthesia, lung function.

  17. News on Deep Mixing

    Science.gov (United States)

    Lattanzio, John C.; Dearborn, Davis S. P.; Eggleton, Peter P.

    2008-04-01

    We briefly summarize the abundant observational evidence for the need of a ``deep mixing'' mechanism in first-ascent red-giant stars, and probably in AGB stars as well. By the term ``deep mixing'' we mean some mixing mechanism which operates in the radiative zone below the convective envelope, and which transports material from the convective region to hotter regions, near the top of the hydrogen shell, where nuclear burning may take place. We then discuss a recent discovery of deep-mixing caused by the burning of 3He following first dredge-up in low-mass stars. This is expected to be a thermohaline process and preliminary calculations show that it has many of the properties required to explain the observations.

  18. Spontaneous exfoliation of a drying gel.

    Science.gov (United States)

    Chung, Jun Young; Regev, Ido; Mahadevan, L

    2016-09-20

    Wet starch cracks when it dries inhomogeneously, while hot glass cracks when it cools non-uniformly. In both cases, differential shrinkage induced by drying/cooling from the surface causes superficial cracks to grow perpendicular to the surface in different patterns. In contrast with these observations of bulk cracking in brittle materials, when a soft and homogeneously swollen polymer gel dries, differential strains lead to the peeling of a thin layer that spontaneously tears away from the bulk. Continued drying leads to the process repeating itself, forming a peeled-layered structure. The emergent thickness of the exfoliated layer is a function of both the geometry of the original gel and the physical parameters associated with the drying rate and external temperature. We characterize the experimental conditions under which layer peeling can arise, and use simulations to corroborate these observations. Finally, a minimal theory explains the scaling of the peel thickness, consistent with our experiments.

  19. Spontaneous Heterotopic Triplet Pregnancy With Tubal Rupture

    Directory of Open Access Journals (Sweden)

    Lima Arsala MBBS, BBMedSci

    2014-04-01

    Full Text Available The recent increase in heterotopic pregnancies has been largely attributed to the increased use of assisted reproduction technologies. We report the rare case of a multiparous woman with a spontaneous conception resulting in a triplet heterotopic pregnancy: a twin intrauterine pregnancy and a single right tubal ectopic pregnancy. Heterotopic pregnancy is a rare and potentially life-threatening condition in which simultaneous gestations occur at 2 or more implantation sites. It is infrequent in natural conception cycles, occurring in 1:30 000 pregnancies. However, the prevalence is rising with the increased use of assisted reproduction techniques to that of 1:100 to 1:500 in these patient subgroups, highlighting the need to incorporate it into a clinician’s diagnostic algorithm.

  20. [Spontaneous rupture of the esophagus. Case report].

    Science.gov (United States)

    Pădureanu, S; Burcoveanu, C; Mârţ, Laura; Ignat, Mihaela

    2004-01-01

    We present a 50 years old man who was admitted for severe pain in the chest appeared after vomiting, dyspnoea, cardiovascular collapse. The diagnosis of spontaneous perforation of the esophagus (Boerhaave's syndrome) was confirmed by a radiopaque swallow. We performed a laparotomy, mediastinal drainage, cervical esophagostomy and jejunostomy. Postoperatively, the general state was severe--with high fever, important pleurezia, necessitating pleural drainage, mechanical ventilation for 8 days, parenteral and jejunostomy nutrition. It was possible to close the esophagostomy in the 43rd postoperative day. The patient has been dismissed on the 59th day. Five days later he presented in the ER with severe dyspnoea due to tracheal stenosis--emergency tracheotomy was performed, followed by resection of the stenotic cartilages.