Sample records for high gain spontaneous

  1. Theory of high gain cavity-enhanced spontaneous parametric down-conversion

    NASA Astrophysics Data System (ADS)

    Zieli?ska, Joanna A.; Mitchell, Morgan W.

    2014-12-01

    We compute the output of multimode cavity-enhanced spontaneous parametric down-conversion (SPDC) for subthreshold, but otherwise arbitrary, gain. We find analytic Bogoliubov transformations that allow us to calculate arbitrary field correlation functions, including the second-order intensity correlation function G(2 )(T ) . The results show evidence of increased coherence due to stimulated SPDC. We extend an earlier model [Lu and Ou, Phys. Rev. A 62, 033804 (2000), 10.1103/PhysRevA.62.033804] to arbitrary gain and finesse, and show the extension gives accurate results in most scenarios. The results will allow simple, analytic description of cavity-based nonclassical light sources for quantum networking, quantum-enhanced sensing of atoms, and generation of highly nonclassical field states.

  2. Gain media edge treatment to suppress amplified spontaneous emission in a high power laser

    DOEpatents

    Hackel, Lloyd A. (Livermore, CA); Soules, Thomas F. (Livermore, CA); Fochs, Scott N. (Livermore, CA); Rotter, Mark D. (San Ramon, CA); Letts, Stephan A. (San Ramon, CA)

    2008-12-09

    A novel method and apparatus for suppressing ASE and parasitic oscillation modes in a high average power laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges using a substantially high index bonding elastomer or epoxy to a predetermined electromagnetic absorbing arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE and parasitic oscillation modes can be effectively suppressed.

  3. Gain media edge treatment to suppress amplified spontaneous emission in a high power laser

    DOEpatents

    Hackel, Lloyd A. (Livermore, CA); Soules, Thomas F. (Livermore, CA); Fochs, Scott N. (Livermore, CA); Rotter, Mark D. (San Ramon, CA); Letts, Stephan A. (San Ramon, CA)

    2011-02-22

    A novel method and apparatus for suppressing ASE and/or parasitic oscillation modes in a laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges to a predetermined electromagnetic absorbing material arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE, parasitic oscillation modes and/or residual pump energy can be effectively suppressed.

  4. Quantum-to-classical transition via fuzzy measurements on high-gain spontaneous parametric down-conversion

    SciTech Connect

    Vitelli, Chiara; Spagnolo, Nicolo [Dipartimento di Fisica, 'Sapienza' Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Toffoli, Lorenzo [Dipartimento di Fisica, 'Sapienza' Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Sciarrino, Fabio [Dipartimento di Fisica, 'Sapienza' Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Istituto Nazionale di Ottica Applicata, Largo Fermi 6, I-50125 Firenze (Italy); De Martini, Francesco [Dipartimento di Fisica, 'Sapienza' Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma (Italy); Accademia Nazionale dei Lincei, via della Lungara 10, I-00165 Roma (Italy)

    2010-03-15

    We consider the high-gain spontaneous parametric down-conversion in a noncollinear geometry as a paradigmatic scenario to investigate the quantum-to-classical transition by increasing the pump power, that is, the average number of generated photons. The possibility of observing quantum correlations in such a macroscopic quantum system through dichotomic measurement will be analyzed by addressing two different measurement schemes, based on different dichotomization processes. More specifically, we will investigate the persistence of nonlocality in an increasing size (n/2)-spin singlet state by studying the change in the correlations form as n increases, both in the ideal case and in presence of losses. We observe a fast decrease in the amount of Bell's inequality violation for increasing system size. This theoretical analysis is supported by the experimental observation of macro-macro correlations with an average number of photons of about 10{sup 3}. Our results shed light on the practical extreme difficulty of observing nonlocality by performing such a dichotomic fuzzy measurement.

  5. Helicopter high gain control

    NASA Technical Reports Server (NTRS)

    Cunningham, T. B.; Nunn, E. C.

    1979-01-01

    High gain control is explored through a design study of the CH-47B helicopter. The plans are designed to obtain the maximum bandwidth possible given the hardware constraints. Controls are designed with modal control theory to specific bandwidths and closed loop mode shapes. Comparisons are made to an earlier complementary filter approach. Bandwidth improvement by removal of limitations is explored in order to establish hardware and mechanization options. Improvements in the pitch axis control system and in the rate gyro sensor noise characteristics in all axes are discussed. The use of rotor state feedback is assessed.

  6. Low-noise high gain dispersion compensating broadband Raman amplifier

    Microsoft Academic Search

    S. A. E. Lewis; F. Koch; S. V. Chernikov; J. R. Taylor

    2000-01-01

    Raman gain module compensating for both loss and dispersion of a 40 km standard telecommunication fiber span over the 1510-1565 nm band is reported. The optimized configuration ensures a low signal-spontaneous noise figure and negligible double Rayleigh scattering noise. The high gain margin of the amplifier makes it applicable for compensation of an 80 km span

  7. Recent Progress in High-Gain FEL Theory

    SciTech Connect

    Huang, Z.; /SLAC

    2005-09-30

    High-gain free electron lasers (FEL) are being developed as extremely bright x-ray sources of a next-generation radiation facility. In this paper, we review the basic theory and the recent progress in understanding the startup, the exponential growth and the saturation of the high-gain process, emphasizing the self-amplified spontaneous emission (SASE). We will also discuss how the FEL performance may be affected by various errors and wakefield effects in the undulator.

  8. Unidirectional high gain brake stop

    NASA Technical Reports Server (NTRS)

    Lang, David J. (Inventor)

    1987-01-01

    This invention relates to a unidirectional high gain brake arrangement that includes in combination a shaft mounted for rotation within a housing. The shaft is rotatable in either direction. A brake is selectively releasably coupled to the housing and to the shaft. The brake has a first member. An intermittent motion device is respectively coupled through the first member to the housing and through a one-way clutch to the shaft. The brake also has a second member that is mechanically coupled to the first brake member and to the housing. The intermittent motion device causes the brake to be activated by movement imparted to the first brake member after a preset number of revolutions of the shaft in one direction. The brake is released by rotation of the shaft in an opposite direction whereby torque transmitted through the one-way clutch to the first brake member is removed.

  9. High temperature electronic gain device

    DOEpatents

    McCormick, J. Byron (Los Alamos, NM); Depp, Steven W. (Los Alamos, NM); Hamilton, Douglas J. (Tucson, AZ); Kerwin, William J. (Tucson, AZ)

    1979-01-01

    An integrated thermionic device suitable for use in high temperature, high radiation environments. Cathode and control electrodes are deposited on a first substrate facing an anode on a second substrate. The substrates are sealed to a refractory wall and evacuated to form an integrated triode vacuum tube.

  10. Quantum effects in high-gain free-electron lasers.

    PubMed

    Schroeder, C B; Pellegrini, C; Chen, P

    2001-11-01

    A many-particle fully quantized theory for a free-electron laser which is valid in the high-gain regime is presented. We examine quantum corrections for the high-gain single-pass free-electron laser. It is shown that quantum effects become significant when the photon energy becomes comparable to the gain bandwidth. The initiation of the free-electron laser process from quantum fluctuations in the position and momentum of the electrons is considered, and the parameter regime for enhanced start-up is identified. Photon statistics of the free-electron laser radiation are discussed, and the photon number statistics for the self-amplified spontaneous emission are calculated. PMID:11736108

  11. The Galileo high gain antenna deployment anomaly

    NASA Technical Reports Server (NTRS)

    Johnson, Michael R.

    1994-01-01

    On April 11, 1991, the Galileo spacecraft executed a sequence that would open the spacecraft's High Gain Antenna. The Antenna's launch restraint had been released just after deployment sequence, the antenna, which opens like an umbrella, never reached the fully deployed position. The analyses and tests that followed allowed a conclusive determination of the likely failure mechanisms and pointed to some strategies to use for recovery of the high gain antenna.

  12. Proton-transfer laser: gain spectrum and amplification of spontaneous emission of 3-hydroxyflavone

    SciTech Connect

    Chou, P.; McMorrow, D.; Aartsma, T.J.; Kasha, M.

    1984-09-27

    The efficient generations of amplified spontaneous emission (ASE) in 3-hydroxyflavone in methylcyclohexane and p-dioxane solutions at 293 K is reported. This application of excited-state proton-transfer tautomerization approaches an ideal four-level laser system involving four different molecular electronic species in separate electronic states and constitutes a photoinduced chemical laser. The gain coefficient for the ASE (530 nm) of 3-hydroxyflavone in methylcyclohexane (293 K) is calculated to be 10-15. Under similar conditions in our apparatus, the gain coefficient is observed to be in the range 7-9 for a proprietary coumarin laser dye (Molectron 70371-4 C485) and for rhodamine-6G. The tunable range for 3-hydroxyflavone is observed to be 518-545 nm. The peak laser power is comparable with that observed for the coumarin dye.

  13. Exponential Gain and Saturation of a Self-Amplified Spontaneous Emission Free-Electron Laser

    Microsoft Academic Search

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

    2001-01-01

    Self-amplified spontaneous emission in a free-electron laser has been proposed for the generation of very high brightness coherent x-rays. This process involves passing a high-energy, high-charge, short-pulse, low-energy-spread, and low-emittance electron beam through the periodic magnetic field of a long series of high-quality undulator magnets. The radiation produced grows exponentially in intensity until it reaches a saturation point. We report

  14. Angular multiplexing as a technique for short-pulse amplification in a high-gain xenon amplifier

    Microsoft Academic Search

    R. P. Sandoval

    1978-01-01

    Experimental demonstration of the angular-multplexing technique on a high-gain Xe laser is outlined. This technique proposes to amplify short laser pulses by sequentially passing these pulses through the final amplifier at slightly different angles. The properties of the Xe laser amplifier are ascertained, particularly the small signal gain, saturation intensity, and spontaneous emission parameters. It is shown that a train

  15. Progress toward high-gain laser fusion

    SciTech Connect

    Storm, E.

    1988-09-28

    A 1985-1986 Review of the US inertial confinement fusion program by the National Academy of Sciences concluded that five more years might be required to obtain enough data to determine the future course of the program. Since then, data from the Nova laser and from the Halite/Centurion program have resolved most of the outstanding problems identified by the NAS review. In particular, we now believe that we can produce a sufficiently uniform target; that we can keep the energy content in hot electrons and high-energy photons low enough (/approximately/1--10% of drive energy, depending on target design) and achieve enough pulse-shaping accuracy (/approximately/10%, with a dynamic range of 100:1) to keep the fuel on a near-Fermi-degenerate adiabat; that we can produce an /approximately/100-Mbar pressure pulse of sufficient uniformity (/approximately/1%), and can we control hydrodynamic instabilities so that the mix of the pusher into the hot spot is low enough to permit marginal ignition. These results are sufficiently encouraging that the US Department of Energy is planning to complete a 10-MJ laboratory microfusion facility to demonstrate high-gain ICF in the laboratory within a decade. 22 refs., 1 fig.

  16. High gain, multiatmosphere CO2 laser amplifier

    NASA Astrophysics Data System (ADS)

    Stuart, G. C.; Houtman, H.; Meyer, J.

    1987-02-01

    A novel TE discharge, 15-mm aperture, multiatmosphere, CO2 laser amplifier is described, with measured electrical characteristics and gain measurements on the 9.294-micron, 9R (16) line. The electrical circuit used in this amplifier is a realistic alternative to the Marx bank or conventional LC inversion circuit and, similarly, it would be useful for excitation of other gas lasers as well. This automatically preionized, double-sided, fourfold LC inversion circuit uses only one spark gap, and it is shown to provide small-signal gains of 5.7 percent/cm, at 120 J/l atm and 10 atm. The generalization to an n-stage device, which would be suitable for higher pressures, and larger apertures, is discussed.

  17. High upconversion optical gain of Er3+-doped tellurite glass

    NASA Astrophysics Data System (ADS)

    Fu, S. B.; Chen, B. J.; Zhang, J. S.; Li, X. P.; Zhong, H.; Tian, B. N.; Wang, Y. Z.; Sun, M.; Zhang, X. Q.; Cheng, L. H.; Zhong, H. Y.; Xia, H. P.

    2014-06-01

    The upconversion technique of rare-earth-doped glasses or crystals is a potential route for achieving short-wavelength lasers (SWLs). The optical gain is an important parameter for evaluating lasing medium performance. Therefore, upconversion luminescence in glass with composition of 70TeO2-9PbF2-10AlF3-10BaF2-1Er2O3 was demonstrated, and the small-signal optical gain was measured via an amplified spontaneous emission technique when the sample was excited with a 980 nm laser. It was found that the optical gain was as large as 4.0 dB/cm, thus indicating that this glass may be a good medium for SWLs.

  18. Temporal coherence of a photonic crystal nanocavity laser with high spontaneous emission coupling factor

    Microsoft Academic Search

    Masahiro Nomura; Satoshi Iwamoto; Naoto Kumagai; Yasuhiko Arakawa

    2007-01-01

    Temporal coherence of a continuous-wave photonic crystal nanocavity laser is investigated in detail using interference experiments at room temperature. The nanocavity laser operates at 1.3mum with InAs quantum dot gain material and has a very high spontaneous emission coupling factor beta=0.9 with a threshold absorbed pump power of ˜375nW . The coherence around the laser threshold of such a high-

  19. High gain Sierpinski Gasket fractal shape antenna designed for RFID

    Microsoft Academic Search

    B. R. Franciscatto; T. P. Vuong; G. Fontgalland

    2011-01-01

    In this paper a high gain Sierpinski fractal shape antenna (reader) for RFID applications is proposed. With the increasing needs of multiband, high gain, very directive antennas and good capability of integration of various wireless technologies, the antenna's research can be oriented following different ways. One of them is use fractals elements. Traditionally, an antenna works at a single frequency

  20. Soft-switching interleaved boost converter with high voltage gain

    Microsoft Academic Search

    R. N. A. L. Silva; G. A. L. Henn; P. P. Praca; L. H. S. C. Barreto; D. S. Oliveira Jr; F. L. M. Antunes

    2008-01-01

    In this paper a soft-switching interleaved boost converter with high voltage gain is presented. The high voltage gain converter is far suitable for applications where a high step-up voltage is required, as in some renewable energy systems, which use, for example, photovoltaic panels and\\/or fuel cells. Besides, in order to guarantee small switching losses and, consequently, a high efficiency, a

  1. JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. , NO. , MONTH 2004 1 Dynamics of high gain fiber laser arrays

    E-print Network

    PeleÂ?, Slaven

    fiber laser arrays Jeffrey L. Rogers, Slaven Peles, and Kurt Wiesenfeld (Invited Paper) Abstract-- Recent experiments [1] have shown that a small number of fiber lasers can spontaneously form coherent. In this paper we develop a dynamical model for fiber laser arrays that is valid in the high gain regime

  2. Stacking nonenzymatic circuits for high signal gain

    PubMed Central

    Chen, Xi; Briggs, Neima; McLain, Jeremy R.; Ellington, Andrew D.

    2013-01-01

    Signal amplification schemes that do not rely on protein enzymes show great potential in areas as abstruse as DNA computation and as applied as point-of-care molecular diagnostics. Toehold-mediated strand displacement, a programmable form of dynamic DNA hybridization, can be used to design powerful amplification cascades that can achieve polynomial or exponential amplification of input signals. However, experimental implementation of such amplification cascades has been severely hindered by circuit leakage due to catalyst-independent side reactions. In this study, we systematically analyzed the origins, characteristics, and outcomes of circuit leakage in amplification cascades and devised unique methods to obtain high-quality DNA circuits that exhibit minimal leakage. We successfully implemented a two-layer cascade that yielded 7,000-fold signal amplification and a two-stage, four-layer cascade that yielded upward of 600,000-fold signal amplification. Implementation of these unique methods and design principles should greatly empower molecular programming in general and DNA-based molecular diagnostics in particular. PMID:23509255

  3. Extended Reach GPON Using High Gain Semiconductor Optical Amplifiers

    Microsoft Academic Search

    Derek Nesset; Shamil Appathurai; Russell Davey; T. Kelly

    2008-01-01

    A 1300 nm semiconductor optical amplifier has been developed for extended reach GPON applications. The high gain of 29 dB has and enabled a commercial GPON system to operate over 60 km and with 128-way split.

  4. Computer simulation of space station computer steered high gain antenna

    NASA Technical Reports Server (NTRS)

    Beach, S. W.

    1973-01-01

    The mathematical modeling and programming of a complete simulation program for a space station computer-steered high gain antenna are described. The program provides for reading input data cards, numerically integrating up to 50 first order differential equations, and monitoring up to 48 variables on printed output and on plots. The program system consists of a high gain antenna, an antenna gimbal control system, an on board computer, and the environment in which all are to operate.

  5. Superradiance in the high-gain free-electron laser

    Microsoft Academic Search

    R. Bonifacio; B. W. J. McNeil; P. Pierini

    1989-01-01

    In this paper we describe the effects of slippage on the single-pass high-gain free-electron laser (FEL) amplifier. We use a one-dimensional computational code to show the existence of two new dynamical regimes characterized by a dimensionless parameter K, which is a measure of the slippage in one gain length. We define the long-pulse limit to be when K<<1 or the

  6. High gain amplifiers: Power oscillations and harmonic generation

    SciTech Connect

    Dattoli, G.; Ottaviani, P. L.; Pagnutti, S. [ENEA, Dipartimento Tecnologie Fisiche e Nuovi Materiali, Centro Ricerche Frascati, C.P. 65-00044 Frascati, Rome (Italy)

    2007-08-01

    We discuss the power oscillations in saturated high gain free electron laser amplifiers and show that the relevant period can be written in terms of the gain length. We use simple arguments following from the solution of the pendulum equation in terms of Jacobi elliptic functions. Nontrivial effects due to nonlinear harmonic generation and inhomogeneous broadening are discussed too, as well as the saturated dynamics of short pulses.

  7. Caustic Singularities Of High-Gain, Dual-Shaped Reflectors

    NASA Technical Reports Server (NTRS)

    Galindo, Victor; Veruttipong, Thavath W.; Imbriale, William A.; Rengarajan, Sambiam

    1991-01-01

    Report presents study of some sources of error in analysis, by geometric theory of diffraction (GTD), of performance of high-gain, dual-shaped antenna reflector. Study probes into underlying analytic causes of singularity, with view toward devising and testing practical methods to avoid problems caused by singularity. Hybrid physical optics (PO) approach used to study near-field spillover or noise-temperature characteristics of high-gain relector antenna efficiently and accurately. Report illustrates this approach and underlying principles by presenting numerical results, for both offset and symmetrical reflector systems, computed by GTD, PO, and PO/GO methods.

  8. High Spontaneous Mutation Rate of an Avian Sarcoma Virus

    PubMed Central

    Zarling, David A.; Temin, Howard M.

    1976-01-01

    Three genetically distinct types of chicken sarcoma virus Bratislava 77 (B77 virus) differing in their ability to infect duck cells were identified. B77 virus type I does not infect duck cells; B77 virus type II has a low efficiency of infection of duck cells; and B77 virus type III has a high efficiency of infection of duck cells. B77 viruses type I and III are produced by spontaneous mutation during the growth of B77 virus type II in chicken cells. The spontaneous mutation of B77 virus type II to B77 virus type III occurs with a high rate (approximately 1 mutation per 50 infected cell generations), requires cell replication, and neither occurs during the synthesis of viral DNA on an RNA template nor during the transcription of progeny viral RNA from the provirus. The rate of spontaneous mutation of B77 virus type II to B77 virus type I is greater than the rate of spontaneous mutation of B77 virus type II to B77 virus type III. PMID:173893

  9. High gain proportional rf control stability at TESLA cavities

    NASA Astrophysics Data System (ADS)

    Vogel, Elmar

    2007-05-01

    Fast proportional rf control is used as the basis for rf field regulation in actual linear accelerator projects like the international linear collider (ILC) and the European x-ray free electron laser (XFEL) based on TESLA technology. Additional control loops improve the field regulation by treating repetitive effects and compensating the beam loading. Nevertheless, the ability for high gain operation of the fast loops is desirable for the strong suppression of nonpredictive and nonrepetitive disturbances. TESLA cavities host nine fundamental modes (FMs) where only one is used for beam acceleration. The unwanted FMs have a significant influence on the proportional rf control loop stability at high gains. Within this paper, the stability of proportional rf control loops taking the FMs and digitalization effects into account will be discussed in detail together with measures enabling a significant increase of the gain values.

  10. Radiation Response of Emerging High Gain, Low Noise Detectors

    NASA Technical Reports Server (NTRS)

    Becker, Heidi N.; Farr, William H; Zhu, David Q.

    2007-01-01

    Data illustrating the radiation response of emerging high gain, low noise detectors are presented. Ionizing dose testing of silicon internal discrete avalanche photodiodes, and 51-MeV proton testing of InGaAs/InAlAs avalanche photodiodes operated in Geiger mode are discussed.

  11. Dispersion relations for 1D high-gain FELs

    SciTech Connect

    Webb, S.D.; Litvinenko, V.N.

    2010-08-23

    We present analytical results for the one-dimensional dispersion relation for high-gain FELs. Using kappa-n distributions, we obtain analytical relations between the dispersion relations for various order kappa distributions. Since an exact solution exists for the kappa-1 (Lorentzian) distribution, this provides some insight into the number of modes on the way to the Gaussian distribution.

  12. Topex high-gain antenna system deployment actuator mechanism

    NASA Technical Reports Server (NTRS)

    Jones, Stephen R.

    1991-01-01

    A deployment actuator mechanism was developed to drive a two-axis gimbal assembly and a high-gain antenna to a deployed and locked position on the Jet Propulsion Laboratory Ocean Topography Experiment (TOPEX) satellite. The Deployment Actuator Mechanism requirements, design, test, and associated problems and their solutions are discussed.

  13. A hybrid nanoantenna for highly enhanced directional spontaneous emission

    SciTech Connect

    Chou, R. Yuanying; Lu, Guowei, E-mail: guowei.lu@pku.edu.cn; Shen, Hongming; He, Yingbo; Cheng, Yuqing [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Perriat, Pascal [MATEIS, UMR 5510 CNRS, INSA-Lyon, Université de Lyon, Villeurbanne Cedex 69621 (France); Martini, Matteo; Tillement, Olivier [ILM, UMR 5306 CNRS, Université de Lyon, Villeurbanne Cedex 69622 (France); Gong, Qihuang [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100871 (China)

    2014-06-28

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

  14. High-Frequency Power Gain in the Mammalian Cochlea

    NASA Astrophysics Data System (ADS)

    Maoiléidigh, Dáibhid Ó.; Hudspeth, A. J.

    2011-11-01

    Amplification in the mammalian inner ear is thought to result from a nonlinear active process known as the cochlear amplifier. Although there is much evidence that outer hair cells (OHCs) play a central role in the cochlear amplifier, the mechanism of amplification remains uncertain. In non-mammalian ears hair bundles can perform mechanical work and account for the active process in vitro, yet in the mammalian cochlea membrane-based electromotility is required for amplification in vivo. A key issue is how OHCs conduct mechanical power amplification at high frequencies. We present a physical model of a segment of the mammalian cochlea that can amplify the power of external signals. In this representation both electromotility and active hair-bundle motility are required for mechanical power gain at high frequencies. We demonstrate how the endocochlear potential, the OHC resting potential, Ca2+ gradients, and ATP-fueled myosin motors serve as the energy sources underlying mechanical power gain in the cochlear amplifier.

  15. High resolution BPMS with integrated gain correction system

    SciTech Connect

    Wendt, M.; Briegel, C.; Eddy, N.; Fellenz, B.; Gianfelice, E.; Prieto, P.; Rechenmacher, R.; Voy, D.; /Fermilab; Terunuma, N.; Urakawa, J.; /KEK, Tsukuba

    2009-08-01

    High resolution beam position monitors (BPM) are an essential tool to achieve and reproduce a low vertical beam emittance at the KEK Accelerator Test Facility (ATF) damping ring. The ATF damping ring (DR) BPMs are currently upgraded with new high resolution read-out electronics. Based on analog and digital down-conversion techniques, the upgrade includes an automatic gain calibration system to correct for slow drift effects and ensure high reproducible beam position readings. The concept and its technical realization, as well as preliminary results of beam studies are presented.

  16. High-Gain Harmonic-Generation Free-Electron Laser

    Microsoft Academic Search

    L.-H. Yu; M. Babzien; I. Ben-Zvi; L. F. DiMauro; A. Doyuran; W. Graves; E. Johnson; S. Krinsky; R. Malone; I. Pogorelsky; J. Skaritka; G. Rakowsky; L. Solomon; X. J. Wang; M. Woodle; V. Yakimenko; S. G. Biedron; J. N. Galayda; E. Gluskin; J. Jagger; V. Sajaev; I. Vasserman; OTD-APS

    2000-01-01

    A high-gain harmonic-generation free-electron laser is demonstrated. Our approach uses a laser-seeded free-electron laser to produce amplified, longitudinally coherent, Fourier transform-limited output at a harmonic of the seed laser. A seed carbon dioxide laser at a wavelength of 10.6 micrometers produced saturated, amplified free-electron laser output at the second-harmonic wavelength, 5.3 micrometers. The experiment verifies the theoretical foundation for the

  17. Applications of high power tapered gain region devices

    Microsoft Academic Search

    J. C. Livas; S. R. Chinn; E. S. Kintzer; J. N. Walpole; C. A. Wang; L. J. Missaggia

    1994-01-01

    An important application of tapered gain region semiconductor lasers is as a pump source for erbium doped fiber amplifiers. We have been developing a 1 Watt-class erbium-doped transmitter amplifier for optical intersatellite communications. Previously, high power erbium-doped amplifiers have been demonstrated using erbium-ytterbium codoped fiber and Nd:YAG pumps, but this approach has a lower wall-plug efficiency than directly pumping at

  18. Photometry And Colorimetry Of High Gain Projection Screens

    NASA Astrophysics Data System (ADS)

    Jenkins, A. J.

    1982-02-01

    The introduction of projection screens with high gains has had an important effect on the development of projection television. These screens have very directional reflectance characteristics which have been measured by a specially built goniophotometer. The measurements from the instrument give a direct indication of the field of view that can be obtained from a screen for a given fall in apparent luminance. The measured results can also be used to calculate some of the less obvious photometric and colorimetric consequences of using and misusing these screens.

  19. A high gain antenna system for airborne satellite communication applications

    NASA Technical Reports Server (NTRS)

    Maritan, M.; Borgford, M.

    1990-01-01

    A high gain antenna for commercial aviation satellites communication is discussed. Electromagnetic and practical design considerations as well as candidate systems implementation are presented. An evaluation of these implementation schemes is given, resulting in the selection of a simple top mounted aerodynamic phased array antenna with a remotely located beam steering unit. This concept has been developed into a popular product known as the Canadian Marconi Company CMA-2100. A description of the technical details is followed by a summary of results from the first production antennas.

  20. High-gain resonance Er:glass amplifier

    NASA Astrophysics Data System (ADS)

    Wan, Peng; Liu, Jian

    2011-02-01

    A novel and compact hybrid resonant amplifier has been demonstrated for further scaling energy/power level from 1.55 ?m fiber lasers by using Er3+/Yb3+ co-doped phosphate glass. The seed laser is a pulse shaping fiber laser at an eye safe wavelength of 1.55 ?m. The wavelength was temperature controllable and was stabilized at one of amplifier's resonance wavelengths. Pulse shaping technology provides a vital solution in generating different input wave formats, for both CW and pulsed outputs. For Pulsed amplification, the pulse duration can be varied from microsecond to nanosecond and repetition rate from a few Hz to 250 kHz. Gain as high as 20 dB was obtained for nanosecond pulses at 10 Hz repetition rate, comparing with a single pass gain of only 0.64 dB. High OSNR, high extinction ratio and low background noise were also achieved at this low repetition rate by our new amplification method. In our CW input experiment, an optical conversion efficiency of up to 20% was obtained. This new optical amplifier is very compact. The size of the amplifier is less than 5 mm. It has a great potential for broad applications.

  1. A high gain tunable laser medium - XeF doped Ar crystals

    NASA Astrophysics Data System (ADS)

    Zerza, G.; Kometer, R.; Sliwinski, G.; Schwentner, N.

    1991-03-01

    Small signal gain coefficients are derived from XeF concentrations, absolute emission intensities, line narrowing of amplified spontaneous emission and from amplification measurements on the D-X (286 nm), B-X (411 nm) and C-A (536 nm) transitions. The gain values of the order of 10 to 30/cm for rather low pump energies and the large spectral range can be interesting for ps applications.

  2. Estimation of peak Raman gain coefficients for Barium-Bismuth-Tellurite glasses from spontaneous Raman cross-section experiments.

    PubMed

    Jackson, Jessica; Smith, Charmayne; Massera, Jonathan; Rivero-Baleine, Clara; Bungay, Corey; Petit, Laeticia; Richardson, Kathleen

    2009-05-25

    In this paper we explore the TeO(2)-Bi(2)O(3)-BaO glass family with varied TeO(2) concentration for Raman gain applications, and we report, for the first time, the peak Raman gain coefficients of glasses within this glass family extrapolated from non-resonant absolute Raman cross-section measurements at 785 nm. Estimated Raman gain coefficients show peak values of up to 40 times higher than silica for the main TeO(2) bands. Other optical properties, including index dispersion from the visible to the long wave Infrared (LWIR) are also summarized in this paper. PMID:19466157

  3. Spontaneous Raman Scattering Diagnostics for High-pressure Gaseous Flames

    NASA Technical Reports Server (NTRS)

    Kojima, Jun; Nguyen, Quang-Viet; Reddy, D. R. (Technical Monitor)

    2002-01-01

    A high-pressure (up to 60 atm) gaseous burner facility with optical access that provides steady, reproducible flames with high precision, and the ability to use multiple fuel/oxidizer combinations has been developed. In addition, a high-performance spontaneous Raman scattering system for use in the above facility has also been developed. Together, the two systems will be used to acquire and establish a comprehensive Raman scattering spectral database for use as a quantitative high-pressure calibration of single-shot Raman scattering measurements in high-pressure combustion systems. Using these facilities, the Raman spectra of H2-Air flames were successfully measured at pressures up to 20 atm. The spectra demonstrated clear rotational and ro-vibrational Raman features of H2, N2, and H2O. theoretical Raman spectra of pure rotational H2, vibrational H2, and vibrational N2 were calculated using a classical harmonic-oscillator model with pressure broadening effects and fitted to the data. At a gas temperature of 1889 K for a phi = 1.34 H2-Air flame, the model and the data showed good agreement, confirming a ro-vibrational equilibrium temperature.

  4. Optical resonator design studies for high gain free electron lasers

    SciTech Connect

    McVey, B.D.; Tokar, R.L.; Bender, S.C.

    1987-01-01

    Optical resonator design studies have been performed for free electron laser oscillator configurations driven by an rf linac. The resonator designs were for an FEL configuration with large saturated gain (50 to 100%) through the electron beam-wiggler region. For the case of large saturated gain, the power loading on the mirrors is reduced, however, the resonator design must compensate for the optical gain and refractive properties of the electron beam.

  5. A high gain energy amplifier operated with fast neutrons

    NASA Astrophysics Data System (ADS)

    Rubbia, Carlo

    1995-09-01

    The basic concept and the main practical considerations of an Energy Amplifier (EA) have been exhaustively described in Ref. . Here the concept of the EA is further explored and additional schemes are described which offer a higher gain, a larger maximum power density and an extended burn-up. All these benefits stem from the use of fast neutrons, instead of thermal or epithermal ones, which was the case in Ref. . The higher gain is due both to a more efficient high energy target configuration and to a larger, practical value of the multiplication factor. The higher power density results from the higher permissible neutron flux, which in turn is related to the reduced rate of 233Pa neutron captures (which, as is well known, suppress the formation of the fissile 233U fuel) and the much smaller k variations after switch-off due to 233Pa decays for a given burn-up rate. Finally a longer integrated burn-up is made possible by reduced capture rate by fission fragments of fast neutrons. In practice a 20 MW proton beam (20 mA @ 1 GeV) accelerated by a cyclotron will suffice to operate a compact EA at the level of ?1 GWe. The integrated fuel burn-up can be extended in excess of 100 GW d/ton, limited by the mechanical survival of the fuel elements. Radio-Toxicity accumulated at the end of the cycle is found to be largely inferior to the one of an ordinary Reactor for the same energy produced. Schemes are proposed which make a ``melt-down'' virtually impossible. The conversion ratio, namely the rate of production of 233U relative to consumption is generally larger than unity, which permits production of fuel for other uses. Alternatively the neutron excess can be used to transform unwanted ``ashes'' into more acceptable elements.

  6. High-Gain Avalanche Rushing amorphous Photoconductor (HARP) detector

    NASA Astrophysics Data System (ADS)

    Tanioka, K.

    2009-09-01

    We have been studying a very sensitive image sensor since the early 1980s. In 1985, the author found for the first time that an experimental pickup tube with an amorphous selenium photoconductive target exhibits high sensitivity with excellent picture quality because of a continuous and stable avalanche multiplication phenomenon. We named the pickup tube with an amorphous photoconductive layer operating in the avalanche-mode "HARP": High-gain Avalanche Rushing amorphous Photoconductor. A color camera equipped with the HARP pickup tubes has a maximum sensitivity of 11 lx at F8. This means that the HARP camera is about 100 times as sensitive as that of CCD camera for broadcasting. This ultrahigh-sensitivity HARP pickup tube is a powerful tool for reporting breaking news at night and other low-light conditions, the production of scientific programs, and numerous other applications, including medical diagnoses, biotech research, and nighttime surveillance. In addition, since the HARP target can convert X-rays into electrons directly, it should be possible to exploit this capability to produce X-ray imaging devices with unparalleled levels of resolution and sensitivity.

  7. Solar Dynamics Observatory High Gain Antenna Handover Planning

    NASA Technical Reports Server (NTRS)

    Hashmall, Joseph A.; Mann, Laurie

    2007-01-01

    The Solar Dynamics Observatory (SDO) is planned to launch in early 2009 as a mission to study the solar variability and its impact on Earth. To best satisfy its science goal, SDO will fly in a geosynchronous orbit with an inclination of approximately 29 deg. The spacecraft attitude is designed so that the science instruments point directly at the Sun with high accuracy. One of SDO's principal requirements is to obtain long periods of uninterrupted observations. The observations have an extremely high data volume so SDO must be in continuous contact with the ground during the observation periods. To maintain this contact, SDO is equipped with a pair of high gain antennas (HGAs) transmitting to a pair of ground antennas at the SDO ground station (SDOGS) located in White Sands, New Mexico. Either HGA can transmit to either SDOGS antenna. Neither HGA can be powered down. During a portion of each year, each of the HGA beams will intersect with the SDO body for a portion of the orbit. The original SDO antenna contact plan used each HGA for the half of each year during which its beam would not intersect the spacecraft. No data would be lost except, possibly, when switching from one antenna to another. After this plan was adopted, further analysis showed that daily handovers would be necessary for significant periods of the year. This unexpected need for extensive handovers necessitated that a handover design be developed to minimize the impact on the mission. This antenna handover design was developed and successfully tested with simulated data using the slew rate limits from preliminary jitter analysis. Subsequent analysis provided significant revision of allowed rates requiring modification of the handover plans.

  8. Design of a high linearity and high gain accuracy analog baseband circuit for DAB receiver

    NASA Astrophysics Data System (ADS)

    Li, Ma; Zhigong, Wang; Jian, Xu; Yiqiang, Wu; Junliang, Wang; Mi, Tian; Jianping, Chen

    2015-02-01

    An analog baseband circuit of high linearity and high gain accuracy for a digital audio broadcasting receiver is implemented in a 0.18-?m RFCMOS process. The circuit comprises a 3rd-order active-RC complex filter (CF) and a programmable gain amplifier (PGA). An automatic tuning circuit is also designed to tune the CF's pass band. Instead of the class-A fully differential operational amplifier (FDOPA) adopted in the conventional CF and PGA design, a class-AB FDOPA is specially employed in this circuit to achieve a higher linearity and gain accuracy for its large current swing capability with lower static current consumption. In the PGA circuit, a novel DC offset cancellation technique based on the MOS resistor is introduced to reduce the settling time significantly. A reformative switching network is proposed, which can eliminate the switch resistor's influence on the gain accuracy of the PGA. The measurement result shows the gain range of the circuit is 10–50 dB with a 1-dB step size, and the gain accuracy is less than ±0.3 dB. The OIP3 is 23.3 dBm at the gain of 10 dB. Simulation results show that the settling time is reduced from 100 to 1 ms. The image band rejection is about 40 dB. It only draws 4.5 mA current from a 1.8 V supply voltage.

  9. Dual-Band Plasmonic Enhancement of Ag-NS@SiO 2 on Gain Medium’s Spontaneous Emission

    Microsoft Academic Search

    Jiunn-Woei Liaw; Chuan-Li Liu; Mao-Kuen Kuo

    We present a theoretical study on plasmonic enhancement of molecular fluorescence near a nanocomposite, Ag nanoshell (Ag-NS)\\u000a coated by a gain medium of molecule-doped SiO2 layer. We use an average enhancement factor (AEF), which considers contributions from all possible orientations and locations\\u000a of molecules in the silica layer to estimate the overall performance of Ag-NS@SiO2 at specific excitation and emission

  10. High-power phased array and tailored gain semiconductor lasers

    SciTech Connect

    Lindsey, C.P.

    1987-01-01

    Most phase locked semiconductor laser arrays suffer from undesirable twin lobed farfield patterns, making them unsuitable for many applications. This thesis makes a detailed theoretical and experimental study of this problem, and solves it by tailoring the spatial gain profile across the array. Stripe geometry lasers for use in phased arrays are examined in Chapter 2, as are design considerations for evanescently coupled phased arrays. A powerful numerical method for analyzing a nearly arbitrary one-dimensional dielectric waveguide with gain and/or loss is described. Chapter 3 analyzes in detail the simplest array of two adjacent waveguides, both real index and gain guided and both weakly and strongly coupled. Chapter 4 discusses why a uniform array has a twin lobed farfield pattern, and introduces the concept of a nonuniform real index guided chirped array of lasers with widths which increase monotonically across the array. Chapter 5 demonstrates another method for gain tailoring, the halftone process, which can create nearly arbitrary two-dimensional spatial gain profiles in an optoelectronic device, thereby offering a new degree of freedom to the designer of semiconductor lasers.

  11. Mechanisms underlying obesity resistance associated with high spontaneous physical activity

    PubMed Central

    Teske, Jennifer A.; Billington, Charles J.; Kotz, Catherine M.

    2013-01-01

    Obesity resistance due to elevated orexin signaling is accompanied by high levels of spontaneous physical activity (SPA). The behavioral and neural mechanisms underlying this observation have not been fully worked out. We determined the contribution of hypothalamic orexin receptors (OXR) to SPA stimulated by orexin A (OXA), whether OXA-stimulated SPA was secondary to arousal and whether voluntary wheel running led to compensations in 24-h SPA. We further tested whether orexin action on dopamine one receptors (DA1R) in the substantia nigra (SN) plays an important role in generation of SPA. To test this, SPA response was determined in lean and obese rats with cannulae targeted towards the rostral lateral hypothalamus (rLH) or SN. Sleep/wake states were also measured in rats with rLH cannula and EEG/EMG radiotelemetry transmitters. SPA in lean rats was more sensitive to antagonism of the orexin 1 receptor (OX1R) and in the early response to the orexin 2 agonist. OXA increased arousal equally in lean and obese rodents, which is discordant from the greater SPA response in lean rats. Obesity resistant rats ran more and wheel running was directly related to 24-h SPA levels. The OX1R antagonist, SB-334867-A, and the DA1R antagonist, SCH3390, in SN more effectively reduced SPA stimulated by OXA in OR rats. These data suggest OXA-stimulated SPA is not secondary to enhanced arousal, propensity for SPA parallels inclination to run and that orexin action on dopaminergic neurons in SN may participate in mediation of SPA and running wheel activity. PMID:24161277

  12. High gain cylindrical reflector antennas with low sidelobes

    Microsoft Academic Search

    Atef Z. Elsherbeni

    1989-01-01

    A technique for improving the efficiency of reflector antennas by increasing the gain and lowering the levels of the sidelobes of the far field pattern is investigated. The technique is based on using an array of radiators instead of a single feed element. The number of radiators are selected to be as minimum as possible to facilitate the actual design

  13. Double-pass high-gain low-noise EDFA over S- and C+L-bands by tunable fundamental-mode leakage loss

    NASA Astrophysics Data System (ADS)

    Hung, Chi-Ming; Chen, Nan-Kuang; Lai, Yinchieh; Chi, Sien

    2007-02-01

    We demonstrate a high-gain low-noise double-pass tunable EDFA over S- and C+L-bands by discretely introducing fundamental-mode leakage loss in a 16-m-long standard C-band Er3+-doped fiber. The amplified spontaneous emission at the wavelengths of longer than 1530 nm can be substantially attenuated by the ASE suppressing filters to maintain high population inversion and to squeeze out the optical gain for S-band signals. When the filters are disabled, the gain bandwidth immediately returns back to the C+L-bands. Under S-band operation, a 37 dB small signal gain and a minimum 4.84 dB noise figure at 1486.9 nm are achieved with a 980 nm pump power of 154 mW.

  14. High gain cylindrical reflector antennas with low sidelobes

    NASA Astrophysics Data System (ADS)

    Elsherbeni, Atef Z.

    1989-12-01

    A technique for improving the efficiency of reflector antennas by increasing the gain and lowering the levels of the sidelobes of the far field pattern is investigated. The technique is based on using an array of radiators instead of a single feed element. The number of radiators are selected to be as minimum as possible to facilitate the actual design procedure. The method of moments is then used to evaluate the induced current on the surface of the antenna from which the aperture field distribution, far field pattern and the radiation characteristics of the antenna are computed. The position, amplitude and phase of the complex current of each radiator are optimized in order to enhance the main lobe and suppress the sidelobes by minimizing the effect of edge diffracted fields. Numerical results for the radiation patterns, gain and sidelobe levels for a class of cylindrical antennas such as strip, corner, circular and parabolic reflectors are analyzed and presented.

  15. High-Efficiency DC-DC Converter With High Voltage Gain and Reduced Switch Stress

    Microsoft Academic Search

    Rong-Jong Wai; Chung-You Lin; Rou-Yong Duan; Yung-Ruei Chang

    2007-01-01

    In this paper, a high-efficiency dc-dc converter with high voltage gain and reduced switch stress is proposed. Generally speaking, the utilization of a coupled inductor is useful for raising the step-up ratio of the conventional boost converter. However, the switch surge voltage may be caused by the leakage inductor so that it will result in the requirement of high-voltage-rated devices.

  16. Prolonged hyperphagia with high-fat feeding contributes to exacerbated weight gain in rats with adult-onset obesity

    PubMed Central

    Judge, M. K.; Zhang, J.; Tümer, N.; Carter, C.; Daniels, M. J.; Scarpace, P. J.

    2008-01-01

    Leptin-resistant rats, when given a high-fat (HF) diet, have a delayed normalization of caloric intake and greater weight gain than those on a chow diet. Because aged, obese rats are leptin resistant, these data predict that they will also have a delayed normalization of caloric intake and exacerbated weight gain when provided a HF diet. To investigate this hypothesis, along with the consequences of a HF diet on voluntary wheel running, we compared various ages of rats on a HF or chow diet. HF-fed young rats spontaneously divided into diet-induced obese and diet-resistant rats. However, all aged rats were susceptible to the weight-gaining effects of HF feeding. Rate of initial weight gain was proportional to age, and peak caloric intake on the HF diet and the days required to normalize caloric intake to basal levels increased with age. Responsiveness to peripheral leptin before HF feeding revealed a dose-response decrease in food intake and body weight in the young but no responses in the aged to even the highest dose, 0.5 mg/day. In addition, both age and HF feeding decreased the tendency for wheel running, suggesting the propensity for inactivity with age and HF feeding may contribute to age-related obesity and accelerate the rate of diet-induced obesity. These results demonstrate that aged rats are more susceptible to the detrimental effects of a HF diet. PMID:18596107

  17. Improved noise sensitivity under high-gain feedback in nano-positioning motion systems

    Microsoft Academic Search

    Marcel Heertjes; George Leenknegt; Bram van Goch; Henk Nijmeijer

    2009-01-01

    To avoid an increased noise response under high-gain feedback in nano-positioning motion systems, a nonlinear (N-PID) control design is proposed. The design is of particular interest in the wafer scanning industry where nano-accuracy should be achieved under high-speed motion. In a variable gain controller setting, the N-PID control design has an observer structure with state-dependent low-pass filter characteristics. Under high-gain

  18. NUTRIENT REQUIREMENTS OF HIGH-LEAN GAIN SWINE AT A HIGH ENVIRONMENTAL TEMPERATURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High-lean gain swine initially averaging 85 kg were assigned to 96 individual pens and given one of six diets ranging in the ratio of Total Ileal Digestible (TID) Lysine:Metabolizable Energy (ME) of 1.23 to 2.28 g/MCal. Pigs and feed intake were weighed weekly and backfat was measured on two week i...

  19. Suppression of body weight gain preserves acute insulin response to glucose in the portal vein of spontaneously type 2 diabetic rats with visceral obesity.

    PubMed

    Mori, Yutaka; Kitahara, Yoshirou; Miura, Kyouko; Itoh, Yohta; Tajima, Naoko

    2005-03-01

    The age-related changes in acute insulin response after glucose loading and the influence of suppression of body weight gain were investigated by using blood samples from portal and peripheral veins. We placed indwelling catheters in the portal vein of 12- and 24- wk-old Otsuka Long-Evans Tokushima fatty (OLETF) rats (n = 8, 12), and age-matched control Long-Evans Tokushima Otsuka (LETO) rats (n = 8, 6). To suppress the body weight gain, 6 out of 12 OLETF rats were fed chow containing 50 ppm voglibose (VOG) from 8 until 24 wk of age. After fasting for 17 h, rats underwent 1 g/kg oral glucose tolerance test (OGTT). Peripheral glucose levels after glucose loading were significantly higher in 12- and 24-wk-old OLETF rats than in the age-matched LETO rats. Values for delta insulin 15 min/delta glucose 15 min (delta I15 min/delta G15 min) in portal blood were 0.029 +/- 0.011 and 0.009 +/- 0.009 (12 wk of age) and 0.03 +/- 0.03 and -0.01 +/- 0.01 (24 wk of age) in the LETO rats and OLETF rats. At the age of 24 wk, the body weights in VOG-treated OLETF rats were significantly lower than those in the OLETF rats. And there was significantly greater acute insulin response to glucose in VOG-treated OLETF rats than in the OLETF rats. Acute insulin response to glucose decreased with advancing age and the suppression of body weight gain preserved the response in spontaneously type 2 diabetic rats with visceral fat obesity. PMID:15888925

  20. A high gain microstrip array adopting EMC dipoles

    NASA Astrophysics Data System (ADS)

    Russo, P.; Ruggieri, M.

    1988-10-01

    The design and operation of microstrip antenna arrays based on commercial feed boards and electromagnetically coupled (EMC) dipoles are described and illustrated with extensive drawings, graphs, and diagrams. The analysis of the radiating element and feeder network is outlined, and a 4 x 1 H-plane array and a 4 x 4 array operating at 11.7-12.5 GHz in linear or circular polarization are characterized in detail. With uniform illumination the latter array had directivity 21.75-22.08 db, gain 20.85-21.27 dB, voltage/standing-wave ratio 1.35-1.55:1, and efficiency 79-85 percent.

  1. High Gain Patch Antenna with Composite Right-Left Handed Structure and Dendritic Cell Metamaterials

    Microsoft Academic Search

    Yahong Liu; Xiaopeng Zhao

    2010-01-01

    We present a novel high-gain patch antenna utilizing composite right-left handed (CRLH) structure and dendritic cell metamaterials.\\u000a The proposed CRLH antenna, composed of modified Sievenpiper mushroom unit-cells, is based on the positive first-order resonance\\u000a mode for high gain. In addition, the dendritic cell metamaterials are used to surround the proposed antenna to further increase\\u000a the antenna directivity and gain due

  2. High gain ytterbium doped Ge pedestal large pitch fiber

    NASA Astrophysics Data System (ADS)

    Gaida, Christian; Stutzki, Fabian; Jansen, Florian; Otto, Hans-Jürgen; Eidam, Tino; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2014-03-01

    Large mode area rod-type fibers have enabled amplification of ultra-short pulses to mJ pulse energy and MW peak powers. For very large mode field areas, fibers have to be designed as rigid rods with typical fiber lengths of around 1 m for efficient operation. A shorter fiber length can be desirable to reduce the packaging size of commercial systems and to decrease the impact of parasitic nonlinear effects for peakpower scaling. The fiber design presented here is based on a modified large-pitch fiber with an effectively higher ytterbium concentration in the fiber core. To achieve index matching the cladding index needs to be changed. In this contribution we propose to co-dope the passive host material with germanium to match both indices and to obtain a higher Yb-concentration within the active core. Compared to standard LPF, where the core index is reduced by co-doping the core with Flourine, the ytterbium doping concentration of this novel germanium-pedestal LPF is doubled. A detailed numerical and experimental investigation shows that with short fiber lengths <40cm is feasible to achieve output powers beyond 100W with 10W seed. Significantly higher gains, of nearly 30 dB, can be achieved for fiber lengths in the order of 60cm. A similar gain can be expected in a conventional LPF with 1.20 m length. In conclusion, we demonstrate a fiber design for significantly enhanced energy storage per fiber length and improved pump absorption. This concept will notably reduce the footprint of ultra-short fiber laser systems.

  3. Machine Copy for Proofreading, 2005 ANALYSIS AND DESIGN OF A HIGH-GAIN ANTENNA

    E-print Network

    Paris-Sud XI, Université de

    Machine Copy for Proofreading, 2005 ANALYSIS AND DESIGN OF A HIGH-GAIN ANTENNA BASED ON METALLIC Electromagnetic Bandgap (EBG) material, with metallic wires and without defect is described. To design the antenna], [5], and designing high-gain antennas with a single feed [6]-[16]. This paper presents the analysis

  4. Statistical theory of high-gain free-electron laser saturation Julien Barr,1,2,

    E-print Network

    Dauxois, Thierry

    Statistical theory of high-gain free-electron laser saturation Julien Barré,1,2, * Thierry Dauxois, to predict the saturated state of a single-pass, high-gain free-electron laser. In analogy with the violent of generating coherent and tunable radiation sources, such as free-electron lasers (FELs). In this case

  5. Longitudinally resolved measurements of carrier concentration and gain in 980-nm InGaAs/GaAs high-power quantum well lasers

    NASA Astrophysics Data System (ADS)

    Bennett, Andrew J.; Sargent, Edward H.; Clayton, Rick D.; Kim, H. B.; Xu, Jing Ming

    1997-05-01

    Measurements of longitudinal variation in critical laser parameters such as gain and carrier concentration are invaluable in understanding and diagnosing device performance and failure mechanisms. However, traditional front-facet measurements cannot reveal the variation of these parameters along the length of the laser. Other methods require physical modifications to the laser itself, such as the fabrication of a top window, and are thus invasive. We describe a new experimental technique based on analysis of side spontaneous emission. A tapered optical fiber translated along the side of the laser using a micropositioner collects spontaneous emission from the active region, allowing spatially-resolved gain and carrier concentration measurements to be made. Such measurements can be used to track the evolution of dark lines caused by defects where non-radiative recombination is dominant. We applied this method to a 980 nm high power laser with an In0.2Ga0.8As, 80 angstroms SQW and facets of 90%/10% reflectivity. It was predicted through a 1D rate equation model that the carrier concentration would increase near the high-reflectivity mirror, due to lower optical field intensities. Using the bimolecular recombination equation to determine the carrier density, this expectation was confirmed. The peak modal gain also increased with proximity to the high-reflectivity mirror, and modulations in the gain peak profile attributed to spatial hole burning were observed.

  6. High-frequency spontaneous emission of an electron beam injected into the ionospheric plasma

    Microsoft Academic Search

    J. Lavergnat; R. Pellat

    1979-01-01

    This paper gives a detailed quantitative analysis of the high-frequency spontaneous wave emissions produced by an electron beam injected into the ionospheric plasma. A general discussion about individual-collective and incoherent-coherent characteristics of the emissions is given. Then attention is focused on the spontaneous coherent emission in three different modes: plasma waves, Bernstein modes, and electromagnetic whistler mode. Comparisons with experimental

  7. Current gain and cutoff frequency falloff at high currents

    Microsoft Academic Search

    R. J. Whittier; D. A. Tremere

    1969-01-01

    A theoretical and experimental study of the effects of high-level injection of carriers into a reverse-biased collector-base junction has been performed. Two models which describe the high-current behavior of the junction space-charge region are discussed. The first deals with the formation of a current-induced base region at space-charge-limited current densities. The second model assumes that two-dimensional effects are predominant; at

  8. A Combined High Gain Observer and High-Order Sliding Mode Controller for a DFIG-Based Wind

    E-print Network

    Paris-Sud XI, Université de

    A Combined High Gain Observer and High-Order Sliding Mode Controller for a DFIG-Based Wind Turbine optimization of a DFIG- based wind turbine. The proposed control strategy combines an MPPT using a high gain observer and second-order sliding mode for the DFIG control. This strategy presents attractive features

  9. DFIG-Based Wind Turbine Robust Control Using High-Order Sliding Modes and a High Gain Observer

    E-print Network

    Brest, Université de

    DFIG-Based Wind Turbine Robust Control Using High-Order Sliding Modes and a High Gain Observer is proposed to ensure power extraction optimization of a DFIG- based wind turbine. The proposed control strategy combines an MPPT using a high gain observer and second-order sliding mode for the DFIG control

  10. Collective instabilities and high-gain regime in a free electron laser

    Microsoft Academic Search

    R. Bonifacio; C. Pellegrini; L. M. Narducci

    1984-01-01

    The behavior of a free electron laser in the high gain regime and the conditions for the emergence of a collective instability in the electron beam-undulator-field system are studied. The equations presented here, in the appropriate limit, yield the traditional small gain formula. In the nonlinear regime, numerical solutions of the coupled equations of motion support the correctness of the

  11. A Study on High Gain Circular Waveguide Array Antenna Using Metamaterial Structure

    Microsoft Academic Search

    Li Bin; Wu Bian; Liang Chang-hong

    2006-01-01

    A new method of improving the gain of circular waveguide array antenna using metamaterial structure is presented in this paper. The electromagnetic characteristics of metamaterial and high-gain circular waveguide antenna with the metamaterial structure are studied by using the numerical simulation method, which were also compared with those of the conventional circular waveguide antenna. The simulation results show that this

  12. High gain photoconductive semiconductor switch having tailored doping profile zones

    Microsoft Academic Search

    Albert G. Baca; Guillermo M. Loubriel; Alan Mar; Fred J Zutavern; Harold P. Hjalmarson; Andrew A. Allerman; Thomas E. Zipperian; Martin W. OMalley; Wesley D. Helgeson; Gary J. Denison; Darwin J. Brown; Charles T. Sullivan; Hong Q. Hou

    2001-01-01

    A photoconductive semiconductor switch with tailored doping profile zones beneath and extending laterally from the electrical contacts to the device. The zones are of sufficient depth and lateral extent to isolate the contacts from damage caused by the high current filaments that are created in the device when it is turned on. The zones may be formed by etching depressions

  13. In-circuit-measurement of parasitic elements in high gain high bandwidth low noise transimpedance amplifiers

    NASA Astrophysics Data System (ADS)

    Cochems, P.; Kirk, A.; Zimmermann, S.

    2014-12-01

    Parasitic elements play an important role in the development of every high performance circuit. In the case of high gain, high bandwidth transimpedance amplifiers, the most important parasitic elements are parasitic capacitances at the input and in the feedback path, which significantly influence the stability, the frequency response, and the noise of the amplifier. As these parasitic capacitances range from a few picofarads down to only a few femtofarads, it is nearly impossible to measure them accurately using traditional LCR meters. Unfortunately, they also cannot be easily determined from the transfer function of the transimpedance amplifier, as it contains several overlapping effects and its measurement is only possible when the circuit is already stable. Therefore, we developed an in-circuit measurement method utilizing minimal modifications to the input stage in order to measure its parasitic capacitances directly and with unconditional stability. Furthermore, using the data acquired with this measurement technique, we both proposed a model for the complicated frequency response of high value thick film resistors as they are used in high gain transimpedance amplifiers and optimized our transimpedance amplifier design.

  14. High current gain InGaN=GaN HBTs with C operating temperature

    E-print Network

    Asbeck, Peter M.

    High current gain InGaN=GaN HBTs with 300 C operating temperature D.M. Keogh, P.M. Asbeck, T. Chung, J. Limb, D. Yoo, J.-H. Ryou, W. Lee, S.-C. Shen and R.D. Dupuis High current gain InGaN base, respectively. Device operation was demonstrated at temperatures as high as 300 C. Introduction: InGaN=GaN

  15. High Gain Antenna Gimbal for the 2003-2004 Mars Exploration Rover Program

    NASA Technical Reports Server (NTRS)

    Sokol, Jeff; Krishnan, Satish; Ayari, Laoucet

    2004-01-01

    The High Gain Antenna Assemblies built for the 2003-2004 Mars Exploration Rover (MER) missions provide the primary communication link for the Rovers once they arrive on Mars. The High Gain Antenna Gimbal (HGAG) portion of the assembly is a two-axis gimbal that provides the structural support, pointing, and tracking for the High Gain Antenna (HGA). The MER mission requirements provided some unique design challenges for the HGAG. This paper describes all the major subsystems of the HGAG that were developed to meet these challenges, and the requirements that drove their design.

  16. A very high frequency CMOS Variable Gain Amplifier

    E-print Network

    Tan, Siang Tong

    2001-01-01

    . Linearity of the transconductor B. Source degeneration amplifier C. Analog multiplier. D. Differential pair with diode-connected load. . . . . E. Conclusions 6 8 10 . . . 12 17 HIGH SWING CURRENT MIRROR. 19 A. DC characteristics . B. Bias... level . . . . Page 2 Block diagram of a direct conversion receiver. 3 Single transistor transconductor 4 Differential pair 5 Source degeneration amplifier. 6 Four-quadrant multiplier basic architectures . . . . . . . . 10 7 Multiplier as a...

  17. Enhanced gain and noise figure performance of high concentration Er3+Yb3+-codoped phosphate fiber amplifiers

    Microsoft Academic Search

    B. Mohammadfam; E. Soltani

    2010-01-01

    A full characterization of Er3+-Yb3+ co-doped fiber amplifiers (EYDFA) is done by numerically solving the simultaneous calculation of the rate and propagation equations considering the forward- and backward-amplified spontaneous emissions (ASE +\\/- ) propagation. The effect of erbium and ytterbium codoping concentrations on the gain of the amplifier is evaluated. With optimal calculated parameters, a gain of 32.7 dB and

  18. High gain photoconductive semiconductor switch having tailored doping profile zones

    SciTech Connect

    Baca, Albert G. (Albuquerque, NM); Loubriel, Guillermo M. (Albuquerque, NM); Mar, Alan (Albuquerque, NM); Zutavern, Fred J (Albuquerque, NM); Hjalmarson, Harold P. (Albuquerque, NM); Allerman, Andrew A. (Albuquerque, NM); Zipperian, Thomas E. (Edgewood, NM); O'Malley, Martin W. (Edgewood, NM); Helgeson, Wesley D. (Albuquerque, NM); Denison, Gary J. (Sandia Park, NM); Brown, Darwin J. (Albuquerque, NM); Sullivan, Charles T. (Albuquerque, NM); Hou, Hong Q. (Albuquerque, NM)

    2001-01-01

    A photoconductive semiconductor switch with tailored doping profile zones beneath and extending laterally from the electrical contacts to the device. The zones are of sufficient depth and lateral extent to isolate the contacts from damage caused by the high current filaments that are created in the device when it is turned on. The zones may be formed by etching depressions into the substrate, then conducting epitaxial regrowth in the depressions with material of the desired doping profile. They may be formed by surface epitaxy. They may also be formed by deep diffusion processes. The zones act to reduce the energy density at the contacts by suppressing collective impact ionization and formation of filaments near the contact and by reducing current intensity at the contact through enhanced current spreading within the zones.

  19. High Gain Transformerless DC-DC Converters for Renewable Energy Sources

    E-print Network

    Denniston, Nicholas Aaron

    2011-08-08

    Renewable energy sources including photovoltaic cells, fuel cells, and wind turbines require converters with high voltage gain in order to interface with power transmission and distribution networks. These conversions are conventionally made using...

  20. Microwave radiation from a high-gain free-electron laser amplifier

    Microsoft Academic Search

    T. J. Orzechowski; B. Anderson; W. M. Fawley; D. Prosnitz; E. T. Scharlemann; S. Yarema; D. Hopkins; A. C. Paul; A. M. Sessler; J. Wurtele

    1985-01-01

    A high-gain, high-extraction-efficiency, linearly polarized free-electron laser amplifier has been operated at 34.6 GHz. At low signal levels, expontential gain of 13.4 dB\\/m has been measured. With a 30-kW input signal, saturation was observed with an 80-MW output and a 5 percent extraction efficiency. The results are in good agreement with linear models at small signal levels and nonlinear models

  1. Noise analysis of high-gain, low-noise column readout circuits for CMOS image sensors

    Microsoft Academic Search

    Nobuhiro Kawai; Shoji Kawahito

    2004-01-01

    The temporal read noise on the signal path of a complementary metal-oxide semiconductor image sensor is analyzed to investigate the effectiveness of high-gain column amplifiers in enhancing sensor sensitivity. The signal path examined includes a pixel source follower, a switched-capacitor, noise-cancelling, high-gain amplifier, and a sample-and-hold circuit in each column. It is revealed that the total random readout noise consists

  2. Theta and High-Frequency Activity Mark Spontaneous Recall of Episodic Memories

    PubMed Central

    Burke, John F.; Sharan, Ashwini D.; Sperling, Michael R.; Ramayya, Ashwin G.; Evans, James J.; Healey, M. Karl; Beck, Erin N.; Davis, Kathryn A.; Lucas, Timothy H.

    2014-01-01

    Humans possess the remarkable ability to search their memory, allowing specific past episodes to be re-experienced spontaneously. Here, we administered a free recall test to 114 neurosurgical patients and used intracranial theta and high-frequency activity (HFA) to identify the spatiotemporal pattern of neural activity underlying spontaneous episodic retrieval. We found that retrieval evolved in three electrophysiological stages composed of: (1) early theta oscillations in the right temporal cortex, (2) increased HFA in the left hemisphere including the medial temporal lobe (MTL), left inferior frontal gyrus, as well as the ventrolateral temporal cortex, and (3) motor/language activation during vocalization of the retrieved item. Of these responses, increased HFA in the left MTL predicted recall performance. These results suggest that spontaneous recall of verbal episodic memories involves a spatiotemporal pattern of spectral changes across the brain; however, high-frequency activity in the left MTL represents a final common pathway of episodic retrieval. PMID:25143616

  3. High-precision atom localization via controllable spontaneous emission in a cycle-configuration atomic system.

    PubMed

    Ding, Chunling; Li, Jiahua; Yu, Rong; Hao, Xiangying; Wu, Ying

    2012-03-26

    A scheme for realizing two-dimensional (2D) atom localization is proposed based on controllable spontaneous emission in a coherently driven cycle-configuration atomic system. As the spatial-position-dependent atom-field interaction, the frequency of the spontaneously emitted photon carries the information about the position of the atom. Therefore, by detecting the emitted photon one could obtain the position information available, and then we demonstrate high-precision and high-resolution 2D atom localization induced by the quantum interference between the multiple spontaneous decay channels. Moreover, we can achieve 100% probability of finding the atom at an expected position by choosing appropriate system parameters under certain conditions. PMID:22453461

  4. Repeated allopregnanolone exposure induces weight gain in schedule fed rats on high fat diet.

    PubMed

    Holmberg, E; Johansson, M; Bäckström, T; Löfgren, M; Haage, D

    2015-03-01

    Ingestion of energy rich high fat diets is one of the determining factors associated with the obesity epidemic. Therefore, much can be learned from studies of obesity-related substances given to animals fed a high fat diet. The progesterone metabolite allopregnanolone is a potent positive modulator of the gamma-aminobutyric acid (GABA)A-receptor, and both allopregnanolone and GABA have been implicated in evoking hyperphagia. In this study, food intake and body weight gain were investigated during repeated allopregnanolone exposure. Male Wistar rats were studied when fed chow ad libitum, with chow access for 4h per day or with 45% high fat pellets for 4h per day. Rats on the high fat diet were separated into obesity prone and obesity resistant individuals. Subcutaneous injections of allopregnanolone were given once daily over five consecutive days. Repeated exposure to allopregnanolone lead to increased weight gain, significantly so in schedule fed rats on a high fat diet. The increased weight gain was correlated to an increased energy intake. Both obesity resistant and obesity prone rats responded to allopregnanolone with increased weight gain. Obesity resistant rats treated with allopregnanolone increased their energy intake and ate as much as vehicle treated obesity prone rats. Their weight gain was also increased to the level of obesity prone rats injected with just the vehicle carrier oil. Thus, it appears that allopregnanolone may be one of the endogenous factors involved in weight gain, especially when the diet is rich in fat. PMID:25484355

  5. Plasmonic amplification and suppression in nanowaveguide coupled to gain-assisted high-quality plasmon resonances

    NASA Astrophysics Data System (ADS)

    Im, Song-Jin; Ho, Gum-Song

    2015-04-01

    We study transmission in a nano waveguide coupled to high-quality plasmon resonances for which the metal loss is overcompensated by gain. The on-resonance transmission can vary widely from lower than ?20 dB to higher than 20 dB for a range of gain coefficient. A reversible transition between the high-quality amplification and the suppression can be induced by a quite small change of gain coefficient for a moderately increased distance between the waveguide and the resonator. It is expected that in practice a small change of gain coefficient can be made by flexibly controlling pumping rate or utilizing nonlinear gain. Additionally, based on the frequency-dependant model for gain-transition susceptibility, it is shown that the wide variation of the on-resonance transmission can also be observed for defferent detuning of the gain-transition line-center. Such a widely controllable on-resonance transmission is promising for applications such as well-controlled lumped amplification of surface plasmon-polariton as well as plasmonic switching.

  6. High-gain pseudomorphic InGaAs base ballistic hot-electron device

    SciTech Connect

    Seo, K.; Heiblum, M.; Knoedler, C.M.; Oh, J.E.; Pamulapati, J.; Bhattacharya, P.

    1989-02-01

    The authors report on a high-gain ballistic hot-electron device. The GaAs-AlGaAs heterostructure device, with a 21-nm-thick pseudomorphic In/sub 0.12/Ga/sub 0.88/As base, had a current gain of 27 at 77 K and 41 at 4.2 K. As characteristically seen in ballistic devices, transfer into the 1 valleys limited the maximum gain. The /Gamma/-L valley separation in the strained In/sub 0.12/Ga/sub 0.88/As was estimated to be about 380 meV.

  7. TA 7.4: A High-Swing 2V CMOSOperational Amplifier with Gain Enhancement usinga Replica Amplifier

    E-print Network

    Lee, Hae-Seung "Harry"

    TA 7.4: A High-Swing 2V CMOSOperational Amplifier with Gain Enhancement usinga Replica Amplifier output resistance, butby matching main andreplica amplifiers, high effectiveopen-stageamplifiercircuitdemon- strates gain enhancementfor low-voltage applications. Consider a transconductance amplifier

  8. DEMONSTRATION OF 3D EFFECTS WITH HIGH GAIN AND EFFICIENCY IN A UV FEL OSCILLATOR

    SciTech Connect

    Stephen Benson; George Biallas; Keith Blackburn; James Boyce; Donald Bullard; James Coleman; Cody Dickover; David Douglas; Forrest Ellingsworth; Pavel Evtushenko; Carlos Hernandez-Garcia; Christopher Gould; Joseph Gubeli; David Hardy; Kevin Jordan; John Klopf; James Kortze; Robert Legg; Matthew Marchlik; Steven Moore; George Neil; Thomas Powers; Daniel Sexton; Michelle D. Shinn; Christopher Tennant; Richard Walker; Anne Watson; Gwyn Williams; Frederick Wilson; Shukui Zhang

    2011-03-01

    We report on the performance of a high gain UV FEL oscillator operating on an energy recovery linac at Jefferson Lab. The high brightness of the electron beam leads to both gain and efficiency that cannot be reconciled with a one-dimensional model. Three-dimensional simulations do predict the performance with reasonable precision. Gain in excess of 100% per pass and an efficiency close to 1/2NW, where NW is the number of wiggler periods, is seen. The laser mirror tuning curves currently permit operation in the wavelength range of 438 to 362 nm. Another mirror set allows operation at longer wavelengths in the red with even higher gain and efficiency.

  9. A high-gain, low-noise CMOS amplifier for sampled bio-potential recording

    Microsoft Academic Search

    Robert Rieger; Yan-Ru Huang

    2010-01-01

    There is a growing demand for low-noise, small-size and programmable biopotential acquisition systems. A crucial circuit block is the high-gain amplifier which also constitutes the interface to the patient. We propose a low-power and low-noise front-end with configurable gain for recording of signals such as the electroneurogram (ENG) or electromyogram (EMG). The proposed circuit consists of an input stage using

  10. Multiple-Module High-Gain High-Voltage DC–DC Transformers for Offshore Wind Energy Systems

    Microsoft Academic Search

    Nicholas Denniston; Ahmed M. Massoud; Shehab Ahmed; Prasad N. Enjeti

    2011-01-01

    Renewable energy sources, such as offshore wind farms, require high voltage gains in order to interface with power transmission networks. These conversions are normally made us- ing bulky, complex, and costly transformers and high-voltage ac- dc converters with unnecessary bidirectional power flow capability. Multiple modules of single-switch single-inductor dc- dc converters can reach high gains without transformers in these applications

  11. Development and Testing of a High-Gain Magnetic Flux Compression Generator

    Microsoft Academic Search

    J. V. Parker; T. C. Cavazos; C. E. Roth; J. H. Degnan; G. F. Kiuttu; F. M. Lehr

    2006-01-01

    The performance of a high-gain FCG is often limited by internal electrical breakdown caused by the high voltage generated during operation. Modern diagnostic techniques provide the opportunity to diagnose internal breakdowns so that generator designs can be improved. This paper describes the internal breakdowns observed in the JAKE FCG developed at the AFRL during the late 1990's. A revision to

  12. HIGH GAIN FEL AMPLIFICATION OF CHARGE MODULATION CAUSED BY A HADRON *

    E-print Network

    HIGH GAIN FEL AMPLIFICATION OF CHARGE MODULATION CAUSED BY A HADRON * Vladimir N. LitvinenkoC) scheme [1,2], a modulation of the electron beam density induced by a co- propagation hadron is amplified an hour - for high-energy hadron colliders such as RHIC and LHC [1,2]. Strong cooling, in return, has

  13. The 2.45 GHz 36 W CW Si recessed gate type SIT with high gain and high voltage operation

    Microsoft Academic Search

    Jun-ichi Nishizawa; Kaoru Motoya; Akira Itoh

    2000-01-01

    The Si microwave recess gate type SIT (Static Induction Transistor) has been fabricated and the high drain blocking voltage up to 140 V with high gain was obtained. The power gain of 13.7 dB up to 1.7 GHz, 10 dB at 2 GHz, 6 dB at 3 GHz, and the maximum frequency of oscillation of 4 GHz in common gate

  14. High-gain X-ray free electron laser by beat-wave terahertz undulator

    SciTech Connect

    Chang, Chao; Hei, DongWei [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an City 710024 (China) [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an City 710024 (China); Institute of Energy, Tsinghua University, Beijing 100084 (China); Pellegrin, Claudio; Tantawi, Sami [SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94309 (United States)] [SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94309 (United States)

    2013-12-15

    The THz undulator has a higher gain to realize a much brighter X-ray at saturation, compared with the optical undulator under the same undulator strength and beam quality. In order to fill the high-power THz gap and realize the THz undulator, two superimposed laser pulses at normal incidence to the electron-beam moving direction form an equivalent high-field THz undulator by the frequency difference to realize the high-gain X-ray Free electron laser. The pulse front tilt of lateral fed lasers is used to realize the electron-laser synchronic interaction. By PIC simulation, a higher gain and a larger X-ray radiation power by the beat wave THz undulator could be realized, compared with the optical undulator for the same electron beam parameters.

  15. Spontaneous Steinbeck: The Influence of Arts Integration, Primarily Spontaneous Painting, on the Reader Response of High School Juniors to "The Grapes of Wrath"

    ERIC Educational Resources Information Center

    Klasek, Catherine Huey

    2010-01-01

    This paper addresses my experience with a group of 11th grade students and their reading of The Grapes of Wrath (1939, 2002) by John Steinbeck. I questioned how the application of visual arts integration strategies, specifically the use of spontaneously created paintings, might influence the reader responses of my high school junior-level…

  16. High-content screening assay for identification of chemicals impacting spontaneous activity in zebrafish embryos.

    PubMed

    Raftery, Tara D; Isales, Gregory M; Yozzo, Krystle L; Volz, David C

    2014-01-01

    Although cell-based assays exist, rapid and cost-efficient high-content screening (HCS) assays within intact organisms are needed to support prioritization for developmental neurotoxicity testing in rodents. During zebrafish embryogenesis, spontaneous tail contractions occur from late-segmentation (?19 h postfertilization, hpf) through early pharyngula (?29 hpf) and represent the first sign of locomotion. Using transgenic zebrafish (fli1:egfp) that stably express eGFP beginning at ?14 hpf, we have developed and optimized a 384-well-based HCS assay that quantifies spontaneous activity within single zebrafish embryos after exposure to test chemicals in a concentration-response format. Following static exposure of one embryo per well from 5 to 25 hpf, automated image acquisition procedures and custom analysis protocols were used to quantify total body area and spontaneous activity in live embryos. Survival and imaging success rates across control plates ranged from 87.5 to 100% and 93.3-100%, respectively. Using our optimized procedures, we screened 16 chemicals within the US EPA's ToxCast Phase-I library, and found that exposure to abamectin and emamectin benzoate-both potent avermectins-abolished spontaneous activity in the absence of gross malformations. Overall, compared to existing locomotion-based zebrafish assays conducted later in development, this method provides a simpler discovery platform for identifying potential developmental neurotoxicants. PMID:24328182

  17. Three-dimensional analysis of harmonic generation in high-gain free-electron lasers

    PubMed

    Huang; Kim

    2000-11-01

    In a high-gain free-electron laser (FEL) employing a planar undulator, strong bunching at the fundamental wavelength can drive substantial bunching and power levels at the harmonic frequencies. In this paper we investigate the three-dimensional evolution of harmonic radiation based on the coupled Maxwell-Klimontovich equations that take into account nonlinear harmonic interactions. Each harmonic field is a sum of a linear amplification term and a term driven by nonlinear harmonic interactions. After a certain stage of exponential growth, the dominant nonlinear term is determined by interactions of the lower nonlinear harmonics and the fundamental radiation. As a result, the gain length, transverse profile, and temporal structure of the first few harmonics are eventually governed by those of the fundamental. Transversely coherent third-harmonic radiation power is found to approach 1% of the fundamental power level for current high-gain FEL projects. PMID:11102089

  18. Resolved discrepancies between visible spontaneous Raman cross-section and direct near-infrared Raman gain measurements in TeO2-based glasses.

    PubMed

    Rivero, Clara; Stegeman, Robert; Couzi, Michel; Talaga, David; Cardinal, Thierry; Richardson, Kathleen; Stegeman, George

    2005-06-13

    Disagreements on the Raman gain response of different tellurite-based glasses, measured at different wavelengths, have been recently reported in the literature. In order to resolve this controversy, a multi-wavelength Raman cross-section experiment was conducted on two different TeO2-based glass samples. The estimated Raman gain response of the material shows good agreement with the directly-measured Raman gain data at 1064 nm, after correction for the dispersion and wavelength-dependence of the Raman gain process. PMID:19495394

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  20. Analytical treatment of the high-gain free electron laser equation

    Microsoft Academic Search

    G. Dattoli; S. Lorenzutta; G. Maino; A. Torre

    1996-01-01

    Exact solutions are obtained for the monodimensional and higher dimensional Free Electron Laser high-gain equations. These equations, which belong to the class of integrodifferential Volterra equations are treated within the context of a perturbative approach, yielding suitable closed-form expressions for the relevant solutions. The proposed method allows to obtain a unified analytical formalism for the full FEL dynamics. Numerical results

  1. Design and Analysis of Gain-Flattened Raman Amplifiers with Novel Highly Nonlinear Photonic Crystal Fibers

    Microsoft Academic Search

    Dong Wang; Nianyu Zou; Yoshinori Namihira; Yinghai Zhang; Zhe Kang; Jingjing Liu

    2011-01-01

    In order to get a flat gain among the dense wavelength division multiplexing (DWDM) channels, design and numerical analysis of Raman fiber amplifier (RFA) based on photonic crystal fibers (PCFs) have been done. Simple pure silica square PCFs with 5 rings air-hole and hexagonal PCFs with 8 rings air- hole owning high nonlinearity, low flat-dispersion as well as low confinement

  2. A novel broadband and high gain antenna for GSM, UMTS, and LTE WiMAX applications

    Microsoft Academic Search

    Mehmet Abbak; Cahit Karakus; Ibrahim Akduman

    2010-01-01

    This paper describes the proposed novel broadband and high gain suspended plate antenna and its feeding structure. It is very applicable for applications which include GSM, UMTS, WLAN and LTE Wi-Max technologies. Simulations are performed using a commercial EM software package, additionally suspended plate antenna is realized and validated by measurements. From the network analyzer and anechoic chamber measurements of

  3. High-gain weakly nonlinear flux-modulated Josephson parametric amplifier using a SQUID-array

    E-print Network

    Boyer, Edmond

    High-gain weakly nonlinear flux-modulated Josephson parametric amplifier using a SQUID-array X devices (SQUIDs). This amplifier is parametrically pumped by modulating the flux threading the SQUIDs be obtained with a single SQUID of the same inductance, due to the smaller nonlinearity of the SQUID array. 1

  4. Plasmonic Amplification with Ultra-High Optical Gain at Room Temperature

    E-print Network

    Wang, Wei Hua

    Plasmonic Amplification with Ultra-High Optical Gain at Room Temperature Ning Liu1 , Hong Wei1, ohmic losses are inherent to all plasmonic devices so that further development of integrated plasmonics we show that CdSe nanobelt/Al2O3/Ag hybrid plasmonic waveguides allow for efficient broadband loss

  5. Neural Computation 9, 971983 (1997) Physiological Gain Leads to High ISI Variability in

    E-print Network

    Columbia University

    Neural Computation 9, 971­983 (1997) Physiological Gain Leads to High ISI Variability in a Simple@phy.ucsf.edu, ken@phy.ucsf.edu Abstract To understand the interspike interval (ISI) variability displayed by visual that have previously been proposed. When ISI's are dominated by post­spike recovery, 1= p N arguments hold

  6. High-precision neutron spectrometer for study of spontaneous and ion induced fission

    SciTech Connect

    Batenkov, O.; Blinov, M.; Majorov, M.; Mogaev, A.; Smirnov, S.; Veshikov, A. [V.G. Khlopin Radium Institute, St. Petersburg (Russian Federation); Conde, H.; Elmgren, K.; Hultqvist, S.; Nilsson, J. [Uppsala Univ. (Sweden)] [and others

    1994-12-31

    A high-precision neutron spectrometer system to study the dependences of the fission process is presented. One advantage of the spectrometer is the possibility to investigate both spontaneous fission and fission induced by light or heavy ions of intermediate energies. Systematic errors can thereby be reduced and {sup 252}Cf can be used for calibration purposes. The time evolution in the process is studied by measuring the energy and angular distributions of the emitted neutrons. Some preliminary data is also presented.

  7. Doc2b Is a High-Affinity Ca2+ Spontaneous Neurotransmitter Release

    E-print Network

    McMahon, Harvey

    . H. de Jong,1 Natalia A. Goriounova,1,3 Ron L. P. Habets,5 Yoshimi Takai,5 J. Gerard Borst,4 NilsDoc2b Is a High-Affinity Ca2+ Sensor for Spontaneous Neurotransmitter Release Alexander J. Groffen be addressed. E-mail: sander.groffen@cncr.vu.nl (A.J.G.) and sascha.martens@ univie.ac.at (S.M.) Fig. 1

  8. High Average Power Laser Gain Medium With Low Optical Distortion Using A Transverse Flowing Liquid Host

    DOEpatents

    Comaskey, Brian J. (Walnut Creek, CA); Ault, Earl R. (Livermore, CA); Kuklo, Thomas C. (Oakdale, CA)

    2005-07-05

    A high average power, low optical distortion laser gain media is based on a flowing liquid media. A diode laser pumping device with tailored irradiance excites the laser active atom, ion or molecule within the liquid media. A laser active component of the liquid media exhibits energy storage times longer than or comparable to the thermal optical response time of the liquid. A circulation system that provides a closed loop for mixing and circulating the lasing liquid into and out of the optical cavity includes a pump, a diffuser, and a heat exchanger. A liquid flow gain cell includes flow straighteners and flow channel compression.

  9. High-precision gas gain and energy transfer measurements in Ar-CO2 mixtures

    NASA Astrophysics Data System (ADS)

    ?ahin, Özkan; Kowalski, Tadeusz Z.; Veenhof, Rob

    2014-12-01

    Ar-CO2 is a Penning mixture since a fraction of the energy stored in Ar 3p5 3 d and higher excited states can be transferred to ionize CO2 molecules. In the present work, concentration and pressure dependence of Penning transfer rate and photon feedback parameter in Ar-CO2 mixtures have been investigated with recent systematic high-precision gas gain measurements which cover the range 1-50% CO2 at 400, 800, 1200, 1800 hPa and gas gain from 1 to 5×105.

  10. High-Gain Regenerative Chirped-Pulse Amplifier Using Photonic Crystal Rod Fiber

    NASA Astrophysics Data System (ADS)

    Ogino, Jumpei; Sueda, Keiichi; Kurita, Takashi; Kawashima, Toshiyuki; Miyanaga, Noriaki

    2013-12-01

    We have demonstrated a high-gain regenerative chirped-pulse amplifier (CPA) using an Yb-doped photonic crystal rod fiber of 100 µm core diameter. The input pulse energy is 150 nJ in a pulse width of 2.5 ns at a repetition rate of 1 kHz with a central wavelength of 1053 nm. At a pump power of 13.2 W, the amplified pulse energy is 0.26 mJ, yielding a gain of 1700.

  11. High gain microstrip antenna element and array on low and high permittivity substrate

    Microsoft Academic Search

    A. Abdel-Rahman; A. K. Verma; A. S. Omar

    2005-01-01

    A new combination of aperture coupled microstrip antenna and a quasi-planar penetrating substrate PVC horn is demonstrated to increase the gain of the patch antenna by 6 dB - 8.68 dB for the patch on substrate having ?r=2.2-13. We also report a new compact 4-element linear aperture coupled microstrip antenna array with surface mounted horn-frame to achieve 3.5 dB gain

  12. High-gain on-chip antenna using a sapphire substrate for implantable wireless medical systems

    NASA Astrophysics Data System (ADS)

    Okabe, Kenji; Akita, Ippei; Ishida, Makoto

    2014-01-01

    This paper presents a high-gain on-chip antenna using a sapphire substrate for implantable wireless medical systems. The antenna model is based on a dipole and the antenna elements are appropriately rolled for impedance matching. The center frequency of the fabricated on-chip antenna was measured as 360 MHz. The return loss was -3.58 dB and the input impedance was 190.5 - j74.7 ? at 360 MHz. The maximum antenna gain of the fabricated on-chip antenna was -29.2 dBi. The on-chip antenna using a sapphire substrate achieved a 12.9 dB higher gain than that using a silicon substrate and successfully induced signal transmission at a distance of 10 cm with a transmitter chip. The implemented on-chip antenna can improve the power efficiency of implantable wireless medical systems by 95%.

  13. A Zero-Voltage-Switching DC–DC Converter With High Voltage Gain

    Microsoft Academic Search

    Hyun-Lark Do

    2011-01-01

    A zero-voltage-switching (ZVS) dc-dc converter with high voltage gain is proposed. It consists of a ZVS boost converter stage and a ZVS half-bridge converter stage and two stages are merged into a single stage. The ZVS boost converter stage pro- vides a continuous input current and ZVS operation of the power switches. The ZVS half-bridge converter stage provides a high

  14. High-power optically pumped VECSEL using a double-well resonant periodic gain structure

    Microsoft Academic Search

    Li Fan; Jörg Hader; Marc Schillgalies; Mahmoud Fallahi; Aramais R. Zakharian; Jerome V. Moloney; Robert Bedford; James T. Murray; Stephan W. Koch; Wolfgang Stolz

    2005-01-01

    We present the design and fabrication of an optically pumped vertical-external-cavity surface-emitting lasers with double-well resonant periodic gain structure. Each double-well consists of two 4-nm-thick InGaAs strained quantum wells. The double-well provides optimum overlap between the quantum wells and the antinodes of the standing wave of laser signal at high-power and high-temperature operation. The structure is more tolerant to variation

  15. High gain, Fast Scan, Broad Spectrum Parallel Beam Wavelength Dispersive X-ray Spectrometer for SEM

    SciTech Connect

    OHara, David

    2009-05-08

    During contract # DE-FG02-ER83545, Parallax Research, Inc. developed a High gain, Fast Scan Broad Spectrum Parallel beam Wavelength Dispersive X-ray Spectrometer for use on Scanning Electron Microscopes (SEM). This new spectrometer allows very fast high resolution elemental analysis of samples in an electron microscope. By comparison to previous WDS spectrometers, it can change from one energy position to another very quickly and has an extended range compared to some similar products.

  16. High-gain visual feedback exacerbates ankle movement variability in children.

    PubMed

    Moon, Hwasil; Kim, Changki; Kwon, MinHyuk; Chen, Yen-Ting; Fox, Emily; Christou, Evangelos A

    2015-05-01

    The purpose was to compare the effect of low- and high-gain visual feedback on ankle movement variability and muscle activation in children and young adults. Six young adults (19.8 ± 0.6 years) and nine children (9.4 ± 1.6 years) traced a sinusoidal target by performing ankle plantar/dorsiflexion movements. The targeted range of motion was 10°, and the frequency of the sinusoidal target was 0.4 Hz for 35 s. Low-gain visual feedback was 0.66°, and high-gain visual feedback was 4.68°. Surface EMG was recorded from the tibialis anterior (TA) muscle. Movement variability amplitude was quantified as the standard deviation of the position fluctuations after the task frequency was removed with a notch filter (second-order; 0.3-0.5 Hz). We quantified the oscillations in movement variability and TA EMG burst using the following frequency bands: 0-0.3, 0.3-0.6, 0.6-0.9, 0.9-1.2, and 1.2-1.5 Hz. Children exhibited greater movement variability than young adults, which was exacerbated during the high-gain visual feedback condition (P < 0.05). The greater ankle movement variability in children at the high-gain visual feedback condition was predicted by greater power within the 0-0.3 Hz of their movement variability (R (2) = 0.51, P < 0.001). The greater power in movement variability from 0 to 0.3 Hz in children was predicted by greater power within the 0-0.3 Hz in their TA EMG burst activity (R (2) = 0.6, P < 0.001). The observed deficiency in movement control with amplified visual feedback in children may be related to an ineffective use of visual feedback and the immaturity of the cortico-motor systems. PMID:25744054

  17. The Physics of Advanced High-Gain Targets for Inertial Fusion Energy

    NASA Astrophysics Data System (ADS)

    Perkins, L. John

    2010-11-01

    In ca. 2011-2012, the National Ignition Facility is poised to demonstrate fusion ignition and gain in the laboratory for the first time. This key milestone in the development of inertial confinement fusion (ICF) can be expected to engender interest in the development of inertial fusion energy (IFE) and expanded efforts on a number of advanced targets that may achieve high fusion energy gain at lower driver energies. In this tutorial talk, we will discuss the physics underlying ICF ignition and thermonuclear burn, examine the requirements for high gain, and outline candidate R&D programs that will be required to assess the performance of these target concepts under various driver systems including lasers, heavy-ions and pulsed power. Such target concepts include those operating by fast ignition, shock ignition, impact ignition, dual-density, magnetically-insulated, one- and two-sided drive, etc., some of which may have potential to burn advanced, non-DT fusion fuels. We will then delineate the role of such targets in their application to the production of high average fusion power. Here, systems studies of IFE economics suggest that we should strive for target fusion gains of around 100 at drive energies of 1MJ, together with corresponding rep-rates of up to 10Hz and driver electrical efficiencies around 15%. In future years, there may be exciting opportunities to study such ``innovative confinement concepts'' with prospects of fielding them on facilities such as NIF to obtain high fusion energy gains on a single shot basis.

  18. Inertial Confinement Fusion: steady progressInertial Confinement Fusion: steady progress towards ignition and high gaintowards ignition and high gain

    E-print Network

    ignition and high gaintowards ignition and high gain (summary talk)(summary talk) M. M. Basko Institute, Vilamoura, Portugal. #12;Main route to ignition: indirect laser drive with central hot-spot ignition and ignition implosion DT capsule hohlraum case ~ 30 m of Au (or Pb)µ laser beams 5.5 mm 9.5 mm ablator DT ice

  19. Gain-assisted high-dimensional self-trapped laser beams at very low light levels

    SciTech Connect

    Li Huijun [Institute of Nonlinear Physics, Zhejiang Normal University, Jinhua 321004, Zhejiang (China); Dong Liangwei [Department of Physics, Zhejiang Normal University, Jinhua 321004, Zhejiang (China); Hang Chao [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China); Huang Guoxiang [Institute of Nonlinear Physics, Zhejiang Normal University, Jinhua 321004, Zhejiang (China); State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China)

    2011-02-15

    We propose a scheme to generate high-dimensional self-trapped laser beams at a very low light intensity via atomic coherence. The system we consider is a resonant four-level atomic ensemble, working in an active Raman gain regime and at room temperature. We derive a high-dimensional nonlinear envelope equation for a signal field with a specific saturable nonlinearity. We show that because of the quantum interference effect induced by a control field, the imaginary part of the coefficients of the signal-field envelope equation can be much smaller than their real part. We demonstrate that the system supports gain-assisted, stable, high-dimensional spatial optical solitons and long-lifetime vortices, which can be produced with light power at the microwatt level.

  20. High-efficiency high-gain monolithic heterostructure FET amplifier at 31 GHz

    NASA Technical Reports Server (NTRS)

    Tserng, H. Q.; Saunier, P.; Kao, Y.-C.

    1993-01-01

    A three-stage heterostructure FET monolithic amplifier has achieved a power-added efficiency of 36 percent with 200 mW output and 18 dB gain at 31 GHz. At a higher drain voltage, the output power increases to 280 mW (with 17.5 dB gain and 31 percent PAE) at a power density of 0.7 W/mm. The MMIC chip measures 2.63 x 1.35 sq mm and requires only a single drain bias and a single gate bias.

  1. High-performance adhesives resulting from spontaneous formation of nanogels within miniemulsion particles.

    PubMed

    Daniloska, Vesna; Carretero, Paula; Tomovska, Radmila; Paulis, Maria; Asua, José M

    2014-03-12

    Molecular structure plays a crucial role in determining the final properties of pressure-sensitive adhesives. Here, we demonstrate that the molecular structure of polyurethane/(meth)acrylic hybrids synthesized by miniemulsion photopolymerization changes during storage of the dispersion at room temperature because of the spontaneous formation of nanogels by the assembly of polymer chains within the polymer particles. Analysis of the nanogel structure by asymmetric-flow field-flow fractionation allows identification of the molecular structure that provides the unusual combination of high tack adhesion and excellent shear resistance at high temperature [maximum value of the shear-adhesion failure temperature (SAFT) test, >210 °C]. PMID:24484476

  2. Enhanced gain and noise figure performance of high concentration Er3+-Yb3+-codoped phosphate fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Mohammadfam, B.; Soltani, E.

    2010-06-01

    A full characterization of Er3+-Yb3+ co-doped fiber amplifiers (EYDFA) is done by numerically solving the simultaneous calculation of the rate and propagation equations considering the forward- and backward-amplified spontaneous emissions (ASE +/- ) propagation. The effect of erbium and ytterbium codoping concentrations on the gain of the amplifier is evaluated. With optimal calculated parameters, a gain of 32.7 dB and a fiber length of 3.54 cm with pump and signal powers of 200 mWand 1 ?W in optimal codoping concentrations is obtained. Simulations have been done for gain characteristic and noise figure of an erbium-doped fiber amplifier (EDFA) with parameters similar to EYDFA to compare the obtained results. The proposed model and simulation results are validated with published experimental results.

  3. Suppression of parasitics and pencil beams in the high-gain National Ignition Facility multipass preamplifier

    NASA Astrophysics Data System (ADS)

    Moran, Bryan D.; Dane, C. Brent; Crane, John K.; Martinez, Mikael D.; Penko, Frank A.; Hackel, Lloyd A.

    1998-06-01

    The multi-pass amplifier (MPA) is the last subsystem of the NIF preamplifier, which feeds the main amplification stages of the NIF beamline. The MPA is based on a flashlamp pumped 5-cm diameter by 48 cm long Nd:glass rod amplifier operated at a single pass small signal gain of 15 to 17. The MPA is an off-axis multi-pass image relayed system, which uses two gain isolating image relaying telescopes and passive polarization switching using a Faraday rotator to output the pulse. We describe the MPA system, techniques used to avoid parasitic oscillation at high gain, and suppression of pencil beams. The system is used to generate a well- conditioned 22-joule output from one millijoule input. The output pulse requirements include 22 joules in a square, flat topped beam, and with near field spatial contrast of <5% RMS, square pulse temporal distortion <2.3, and an RMS energy stability of <3%. All of these requirements have been exceeded. The largest impediment to successful operation was overcoming parasitic oscillation. Sources of oscillation could be generally divided into two categories: those due to birefringence, which compromised the polarization contrast of the system; and those due to unwanted reflections from optical surfaces. Baffling in the vacuum spatial filters helps to control the system sensitivity to unwanted stray reflections from flat AR coated surfaces. Stress birefringence in the rather large glass volume of the rod (942 cm3) and the four vacuum loaded lenses are significant, as each of these elements is double passed between each polarizing beam splitter pass. This lowers the polarization contrast of the system, which can prevent the system from operating at sufficient gain. Careful analysis and layout of the MPA architecture has allowed us to address the challenges posed by a system small signal gain of approximately equals 33000 and with an output pulse of as high as 27 joules.

  4. High-gain backup antenna design for Pioneer Venus Orbiter spacecraft

    NASA Technical Reports Server (NTRS)

    Glaser, J. I.

    1986-01-01

    The development and performance is described of a high-gain antenna designed to serve on the Pioneer Venus Orbiter spacecraft as a backup to the principal high-gain antenna unit in the unlikely event the mechanically despun antenna mechanism malfunctioned. The final design, a center-fed standing wave array of six sleeve dipoles enclosed in a fiber glass radome, performed successfully, as did all the antennas, on the Pioneer Orbiter spacecraft which was launched on May 20, 1978, as part of the Pioneer Venus mission. Photographs of experimental models giving details of design and construction are included, as well as graphs showing measured pattern and impedance matching characteristics of the subject antenna.

  5. High-Gain Fully Printed Organic Complementary Circuits on Flexible Plastic Foils

    Microsoft Academic Search

    A. Daami; E. Bergeret; E. Benevent; P. Pannier; R. Coppard; Mathieu Guerin

    2011-01-01

    We present several fully printed organic complemen- tary circuits using n- and p-type organic thin-film transistors. n-Type and p-type devices are developed on a flexible poly- ethylene-naphthalate substrate. All organic layers are deposited using a low-cost screen-printing technique. The inverters show a high gain and a switching point at exactly V DD\\/2. A seven-stage voltage-controlled oscillator (VCO) is designed with

  6. First Ultraviolet High-Gain Harmonic-Generation Free-Electron Laser

    Microsoft Academic Search

    L. H. Yu; L. Dimauro; A. Doyuran; W. S. Graves; E. D. Johnson; R. Heese; S. Krinsky; H. Loos; J. B. Murphy; G. Rakowsky; J. Rose; T. Shaftan; B. Sheehy; J. Skaritka; X. J. Wang; Z. Wu

    2003-01-01

    We report the first experimental results on a high-gain harmonic-generation (HGHG) free-electron laser (FEL) operating in the ultraviolet. An 800nm seed from a Ti:sapphire laser has been used to produce saturated amplified radiation at the 266nm third harmonic. The results confirm the predictions for HGHG FEL operation: stable central wavelength, narrow bandwidth, and small pulse-energy fluctuation.

  7. High Gestational Weight Gain Does Not Improve Birth Weight in a Cohort of African American Adolescents

    Microsoft Academic Search

    Jennifer Notkin Nielsen; Frank R. Witter; Shih-Chen Chang; Jeri Mancini; Maureen Schulman Nathanson; Laura E. Caulfield

    2006-01-01

    Background: Because pregnant African American women and teensareatriskoflowbirthweight,theyarefrequentlycounseledto strive for gestational weight gains at the upper limits of the Institute of Medicine's recommended ranges. Objective:Theobjectivewastoexaminewhethersuchweightgains improvebirthoutcomesinacohortofdisadvantagedAfricanAmer- ican adolescents of low (19.8), average (19.8 to26.0), or high (26) prepregnancy body mass index (BMI; in kg\\/m2). Design: Data were extracted from the medical charts of 1120 Afri- can American adolescents who received

  8. Adaptive gain equalizer in high-index-contrast SiON technology

    Microsoft Academic Search

    B. J. Offrein; F. Horst; G. L. Bona; R. Germann; H. W. M. Salemink; R. Beyeler

    2000-01-01

    An adaptive gain equalization filter is presented. The filter is based on the resonant coupler principle, a cascade of power couplers and delay lines. Reconfigurability and tuning is achieved by varying coupling strength and delay line length via the thermo optic effect. A device consisting of seven delay line stages was realized in high-index-contrast silicon-oxynitride technology. This device flattens the

  9. Norepinephrine and Epinephrine-deficient Mice Gain Weight Normally on a High-fat Diet

    Microsoft Academic Search

    Linda Ste. Marie; Serge Luquet; Wendy Curtis; Richard D. Palmiter

    2005-01-01

    Objective: Signaling through adrenergic receptors (ARs) by norepinephrine (NE) and epinephrine (Epi) regulates weight gain when mice are fed a high-fat diet (HFD) by controlling diet-induced thermogenesis. Thus, one would predict that mice unable to make NE\\/Epi because of inactivation of the dopamine ?-hydroxylase gene (Dbh-null mice) would have a propensity to become obese. We characterized the response of Dbh-null

  10. Optimization of single-step tapering amplitude and energy detuning for high-gain FELs

    NASA Astrophysics Data System (ADS)

    Li, He-Ting; Jia, Qi-Ka

    2015-01-01

    We put forward a method to optimize the single-step tapering amplitude of undulator strength and initial energy tuning of electron beam to maximize the saturation power of high gain free-electron lasers (FELs), based on the physics of longitudinal electron beam phase space. Using the FEL simulation code GENESIS, we numerically demonstrate the accuracy of the estimations for parameters corresponding to the linac coherent light source and the Tesla test facility.

  11. Robust Stabilization of Non-Minimum Phase Nonlinear Systems Using Extended High-Gain Observers

    Microsoft Academic Search

    Shahid Nazrulla; Hassan K. Khalil

    2011-01-01

    A robust, stabilizing output feedback controller for systems in the normal form, which could potentially in- clude unstable zero dynamics, is presented. The control scheme adopted herein incorporates continuously-implemented sliding mode control—chosen for its robustness properties as well as its ability to prescribe or constrain the motion of trajectories in the sliding phase—and an extended high gain observer to estimate

  12. Spontaneous high piezoelectricity in poly(vinylidene fluoride) nanoribbons produced by iterative thermal size reduction technique.

    PubMed

    Kanik, Mehmet; Aktas, Ozan; Sen, Huseyin Sener; Durgun, Engin; Bayindir, Mehmet

    2014-09-23

    We produced kilometer-long, endlessly parallel, spontaneously piezoelectric and thermally stable poly(vinylidene fluoride) (PVDF) micro- and nanoribbons using iterative size reduction technique based on thermal fiber drawing. Because of high stress and temperature used in thermal drawing process, we obtained spontaneously polar ? phase PVDF micro- and nanoribbons without electrical poling process. On the basis of X-ray diffraction (XRD) analysis, we observed that PVDF micro- and nanoribbons are thermally stable and conserve the polar ? phase even after being exposed to heat treatment above the melting point of PVDF. Phase transition mechanism is investigated and explained using ab initio calculations. We measured an average effective piezoelectric constant as -58.5 pm/V from a single PVDF nanoribbon using a piezo evaluation system along with an atomic force microscope. PVDF nanoribbons are promising structures for constructing devices such as highly efficient energy generators, large area pressure sensors, artificial muscle and skin, due to the unique geometry and extended lengths, high polar phase content, high thermal stability and high piezoelectric coefficient. We demonstrated two proof of principle devices for energy harvesting and sensing applications with a 60 V open circuit peak voltage and 10 ?A peak short-circuit current output. PMID:25133594

  13. Small-signal gain measurements for highly doped and co-doped Er3+:YAG at 2.936 ?m

    NASA Astrophysics Data System (ADS)

    Joshi, Abhijeet; Furtado, Mario; Shori, Ramesh; Stafsudd, Oscar M.

    2014-03-01

    Direct small-signal gain measurements have been made for a 50% doped Er3+:YAG rods for the 2.936 ?m wavelength. We also provide gain measurements for 55% Er3+:YAG and co-doped 55% Er3+:YAG rods. Erbium doped solid-state lasers are typically used in a flash-pumped configuration, where the gain dynamics is highly dependent on the pump-pulse length. In this paper we have reported the small-signal gain over the pulse duration, along with average small-signal gain, so as to provide the laser-engineer with data to efficiently design the mid-IR laser system.

  14. Gains of ubiquitylation sites in highly conserved proteins in the human lineage

    PubMed Central

    2012-01-01

    Background Post-translational modification of lysine residues of specific proteins by ubiquitin modulates the degradation, localization, and activity of these target proteins. Here, we identified gains of ubiquitylation sites in highly conserved regions of human proteins that occurred during human evolution. Results We analyzed human ubiquitylation site data and multiple alignments of orthologous mammalian proteins including those from humans, primates, other placental mammals, opossum, and platypus. In our analysis, we identified 281 ubiquitylation sites in 252 proteins that first appeared along the human lineage during primate evolution: one protein had four novel sites; four proteins had three sites each; 18 proteins had two sites each; and the remaining 229 proteins had one site each. PML, which is involved in neurodevelopment and neurodegeneration, acquired three sites, two of which have been reported to be involved in the degradation of PML. Thirteen human proteins, including ERCC2 (also known as XPD) and NBR1, gained human-specific ubiquitylated lysines after the human-chimpanzee divergence. ERCC2 has a Lys/Gln polymorphism, the derived (major) allele of which confers enhanced DNA repair capacity and reduced cancer risk compared with the ancestral (minor) allele. NBR1 and eight other proteins that are involved in the human autophagy protein interaction network gained a novel ubiquitylation site. Conclusions The gain of novel ubiquitylation sites could be involved in the evolution of protein degradation and other regulatory networks. Although gains of ubiquitylation sites do not necessarily equate to adaptive evolution, they are useful candidates for molecular functional analyses to identify novel advantageous genetic modifications and innovative phenotypes acquired during human evolution. PMID:23157318

  15. Movement Recognition Technology as a Method of Assessing Spontaneous General Movements in High Risk Infants

    PubMed Central

    Marcroft, Claire; Khan, Aftab; Embleton, Nicholas D.; Trenell, Michael; Plötz, Thomas

    2015-01-01

    Preterm birth is associated with increased risks of neurological and motor impairments such as cerebral palsy. The risks are highest in those born at the lowest gestations. Early identification of those most at risk is challenging meaning that a critical window of opportunity to improve outcomes through therapy-based interventions may be missed. Clinically, the assessment of spontaneous general movements is an important tool, which can be used for the prediction of movement impairments in high risk infants. Movement recognition aims to capture and analyze relevant limb movements through computerized approaches focusing on continuous, objective, and quantitative assessment. Different methods of recording and analyzing infant movements have recently been explored in high risk infants. These range from camera-based solutions to body-worn miniaturized movement sensors used to record continuous time-series data that represent the dynamics of limb movements. Various machine learning methods have been developed and applied to the analysis of the recorded movement data. This analysis has focused on the detection and classification of atypical spontaneous general movements. This article aims to identify recent translational studies using movement recognition technology as a method of assessing movement in high risk infants. The application of this technology within pediatric practice represents a growing area of inter-disciplinary collaboration, which may lead to a greater understanding of the development of the nervous system in infants at high risk of motor impairment. PMID:25620954

  16. Interpolating gain-scheduled H? loop shaping design for high speed ball screw feed drives.

    PubMed

    Dong, Liang; Tang, WenCheng; Bao, DaFei

    2015-03-01

    This paper presents a method to design servo controllers for flexible ball screw drives with time-varying dynamics, which are mainly due to the time-varying table position and the workpiece mass. A gain-scheduled H? loop shaping controller is designed to achieve high tracking performance against the dynamic variations. H? loop shaping design procedure incorporates open loop shaping by a set of compensators to obtain performance/robust stability tradeoffs. The interpolating gain-scheduled controller is obtained by interpolating the state space model of the linear time-invariant (LTI) controllers estimated for fixed values of the scheduling parameters and a linear least squares problem can be solved. The proposed controller has been compared with P/PI with velocity and acceleration feedforward and adaptive backstepping sliding mode control experimentally. The experimental results indicate that the tracking performance has been improved and the robustness for time-varying dynamics has been achieved with the proposed scheme. PMID:25592980

  17. A bootstrapped, low-noise, and high-gain photodetector for shot noise measurement

    SciTech Connect

    Zhou, Haijun; Yang, Wenhai; Li, Zhixiu; Li, Xuefeng; Zheng, Yaohui, E-mail: yhzheng@sxu.edu.cn [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China)] [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China)

    2014-01-15

    We presented a low-noise, high-gain photodetector based on the bootstrap structure and the L-C (inductance and capacitance) combination. Electronic characteristics of the photodetector, including electronic noise, gain and frequency response, and dynamic range, were verified through a single-frequency Nd:YVO{sub 4} laser at 1064 nm with coherent output. The measured shot noise of 50 ?W laser was 13 dB above the electronic noise at the analysis frequency of 2 MHz, and 10 dB at 3 MHz. And a maximum clearance of 28 dB at 2 MHz was achieved when 1.52 mW laser was illuminated. In addition, the photodetector showed excellent linearities for both DC and AC amplifications in the laser power range between 12.5 ?W and 1.52 mW.

  18. Effects of Bandwidth, Compression Speed, and Gain at High Frequencies on Preferences for Amplified Music

    PubMed Central

    2012-01-01

    This article reviews a series of studies on the factors influencing sound quality preferences, mostly for jazz and classical music stimuli. The data were obtained using ratings of individual stimuli or using the method of paired comparisons. For normal-hearing participants, the highest ratings of sound quality were obtained when the reproduction bandwidth was wide (55 to 16000 Hz) and ripples in the frequency response were small (less than ± 5 dB). For hearing-impaired participants listening via a simulated five-channel compression hearing aid with gains set using the CAM2 fitting method, preferences for upper cutoff frequency varied across participants: Some preferred a 7.5- or 10-kHz upper cutoff frequency over a 5-kHz cutoff frequency, and some showed the opposite preference. Preferences for a higher upper cutoff frequency were associated with a shallow high-frequency slope of the audiogram. A subsequent study comparing the CAM2 and NAL-NL2 fitting methods, with gains slightly reduced for participants who were not experienced hearing aid users, showed a consistent preference for CAM2. Since the two methods differ mainly in the gain applied for frequencies above 4 kHz (CAM2 recommending higher gain than NAL-NL2), these results suggest that extending the upper cutoff frequency is beneficial. A system for reducing “overshoot” effects produced by compression gave small but significant benefits for sound quality of a percussion instrument (xylophone). For a high-input level (80 dB SPL), slow compression was preferred over fast compression. PMID:23172008

  19. Effects of bandwidth, compression speed, and gain at high frequencies on preferences for amplified music.

    PubMed

    Moore, Brian C J

    2012-09-01

    This article reviews a series of studies on the factors influencing sound quality preferences, mostly for jazz and classical music stimuli. The data were obtained using ratings of individual stimuli or using the method of paired comparisons. For normal-hearing participants, the highest ratings of sound quality were obtained when the reproduction bandwidth was wide (55 to 16000 Hz) and ripples in the frequency response were small (less than ± 5 dB). For hearing-impaired participants listening via a simulated five-channel compression hearing aid with gains set using the CAM2 fitting method, preferences for upper cutoff frequency varied across participants: Some preferred a 7.5- or 10-kHz upper cutoff frequency over a 5-kHz cutoff frequency, and some showed the opposite preference. Preferences for a higher upper cutoff frequency were associated with a shallow high-frequency slope of the audiogram. A subsequent study comparing the CAM2 and NAL-NL2 fitting methods, with gains slightly reduced for participants who were not experienced hearing aid users, showed a consistent preference for CAM2. Since the two methods differ mainly in the gain applied for frequencies above 4 kHz (CAM2 recommending higher gain than NAL-NL2), these results suggest that extending the upper cutoff frequency is beneficial. A system for reducing "overshoot" effects produced by compression gave small but significant benefits for sound quality of a percussion instrument (xylophone). For a high-input level (80 dB SPL), slow compression was preferred over fast compression. PMID:23172008

  20. Moderate Volume of High Relative Training Intensity Produces Greater Strength Gains Compared With Low and High Volumes in Competitive Weightlifters

    Microsoft Academic Search

    Juan José González-Badillo; Mikel Izquierdo; Esteban M. Gorostiaga

    2006-01-01

    Gonzalez-Badillo, J.J., M. Izquierdo, and E.M. Gorostiaga. Moderate volume of high relative training in- tensity produces greater strength gains compared with low and high volumes in competitive weightlifters. J. Strength Cond. Res. 20(1)73-81. 2006.—The purpose of this study was to examine the effect of 3 volumes of heavy resistance, average relative training intensity (expressed as a percentage of 1 repetition

  1. Loop gain analysis and development of high-speed high-accuracy current sensors for switching converters

    Microsoft Academic Search

    Hylas Y. H. Lam; Wing-hung Ki; Dongsheng Ma

    2004-01-01

    Loop gain analysis for performance evaluation of current sensors for switching converters is presented. The MOS transistor scaling technique is reviewed and employed in developing high-speed and high-accuracy current-sensors with offset-current cancellation. Using a standard 0.35?m CMOS process, and integrated full-range inductor current sensor for a boost converter is designed. It operated at a supply voltage of 1.5 V with

  2. Suppression of body weight gain preserves acute insulin response to glucose in the portal vein of spontaneously type 2 diabetic rats with visceral obesity

    Microsoft Academic Search

    Yutaka Mori; Yoshirou Kitahara; Kyouko Miura; Yohta Itoh; Naoko Tajima

    2005-01-01

    The age-related changes in acute insulin response after glucose loading and the influence of suppression of body weight gain\\u000a were investigated by using blood samples from portal and peripheral veins. We placed indwelling catheters in the portal vein\\u000a of 12- and 24-wk-old Otsuka Long-Evans Tokushima fatty (OLETF) rats (n=8, 12), and age-matched control Long-Evans Tokushima Otsuka (LETO) rats (n=8, 6).

  3. Broadband optical parametric gain by novel highly nonlinear tellurite hybrid microstructured optical fiber with four zero-dispersion wavelengths

    NASA Astrophysics Data System (ADS)

    Tuan, Tong Hoang; Cheng, Tonglei; Asano, Koji; Duan, Zhongchao; Suzuki, Takenobu; Ohishi, Yasutake

    2014-03-01

    Fiber-optical parametric amplification (FOPA) has been intensively studied and exploited for various interesting applications such as wavelength conversion, wavelength division multiplexing, optical signal processing and so on. However, its efficiency is governed by the fiber nonlinearity and chromatic dispersion. By employing tellurite glass we propose novel highly nonlinear tellurite hybrid microstructured optical fibers (HMOFs) which have nonlinearity of 6642 W-1km-1 and near-zero flattened dispersion profiles from 1.3 to 2.3 ?m with four zero dispersion wavelengths for FOPA applications. The linear phase-mismatch, optical signal gain and gain bandwidth are precisely calculated by using a full propagation constant which includes the contribution of all high-order dispersion parameters. In contrast with silica fibers, the signal gain is shown to be generated in the wavelength regions where ??<-4?P and the parametric gain coefficient g is imaginary. It is shown that the proposed tellurite HMOFs with short fiber length L<90 cm have the gain bandwidth as broad as 760 nm when it is pumped at 1550 nm. The increase in pump power from 1 to 4 W not only increases the signal gain but also broadens the FOPA gain bandwidth. At 1700-nm pump wavelength, the signal gain larger than 14 dB is obtained over a very broad gain bandwidth of 1200 nm (from 1290 to 2490 nm). To our best knowledge, it is the first time that highly nonlinear tellurite HMOFs are demonstrated as attractive candidates for high performance of FOPA.

  4. Spontaneous high-yield hydrogen production from cellulosic materials and water catalyzed by enzyme cocktail

    SciTech Connect

    Ye, Xinhao [Virginia Polytechnic Institute and State University (Virginia Tech); Wang, Yiran [Virginia Polytechnic Institute and State University (Virginia Tech); Hopkins, Robert C. [University of Georgia, Athens, GA; Adams, Michael W. W. [University of Georgia, Athens, GA; Evans, Barbara R [ORNL; Mielenz, Jonathan R [ORNL; Zhang, Y.-H. Percival [Virginia Polytechnic Institute and State University (Virginia Tech)

    2009-01-01

    Carbon-neutral hydrogen gas is a compelling energy carrier, especially for the transportation section. Low-cost hydrogen can be produced from abundant renewable lignocellulosic biomass through a number of methods employing chemical catalysis, biocatalysis or a combination of both, but these technologies suffer from low hydrogen yields (well below the theoretical yield of 12 H2 per glucose), undesired side-products and/or required severe reaction conditions. Here we present a novel in vitro synthetic biology approach for producing near theoretical hydrogen yields from cellulosic materials (cellodextrins) and water at 32oC and 1 atm. These non-natural catabolic pathways containing up to 14 enzymes and one coenzyme degrade cellodextrins initially to glucose-1-phosphate and eventually to CO2, split water and finally release the chemical energy in the form of hydrogen gas. Up to 11.2 H2 per anhydroglucose was produced in a batch reaction. This spontaneous endothermic reaction is driven by entropy gain, suggesting that the thermal energy is adsorbed for generating more chemical energy (hydrogen gas) than that in cellodextrins, i.e., output/input of chemical energy > 1, with an input of ambient-temperature thermal energy.

  5. Oscillator Seeding of a High Gain Harmonic Generation FEL in a Radiator-First Configuration

    SciTech Connect

    Gandhi, P.; Wurtele, J.; Penn, G.; Reinsch, M.

    2012-05-20

    A longitudinally coherent X-ray pulse from a high repetition rate free electron laser (FEL) is desired for a wide variety of experimental applications. However, generating such a pulse with a repetition rate greater than 1 MHz is a significant challenge. The desired high repetition rate sources, primarily high harmonic generation with intense lasers in gases or plasmas, do not exist now, and, for the multi-MHz bunch trains that superconducting accelerators can potentially produce, are likely not feasible with current technology. In this paper, we propose to place an oscillator downstream of a radiator. The oscillator generates radiation that is used as a seed for a high gain harmonic generation (HGHG) FEL which is upstream of the oscillator. For the first few pulses the oscillator builds up power and, until power is built up, the radiator has no HGHG seed. As power in the oscillator saturates, the HGHG is seeded and power is produced. The dynamics and stability of this radiator-first scheme is explored analytically and numerically. A single-pass map is derived using a semi-analytic model for FEL gain and saturation. Iteration of the map is shown to be in good agreement with simulations. A numerical example is presented for a soft X-ray FEL.

  6. ONT High Gain Initiative WRAP (Wide Area Rapid Acoustic Prediction) computational performance section

    SciTech Connect

    McGraw, J.R.; Hedstrom, G.; De Groot, T.

    1990-10-02

    LLNL received a contract during March 1990 to perform three tasks for ONT. This letter report covers Task I which concerned a supercomputing effort in a program termed the High Gain Initiative, which is an anti-submarine (ASW) project that requires substantial computational and signal processing expertise. The core of the computational aspects at the present time is a code called WRAP (Wide Area Rapid Acoustic Prediction). LLNL's objective was to study the WRAP model and determine the feasibility and limits of its optimization. At the present time, the WRAP code runs on a single processor VAX computer.

  7. High Gain Antenna System Deployment Mechanism Integration, Characterization, and Lessons Learned

    NASA Technical Reports Server (NTRS)

    Parong, Fil; Russell, Blair; Garcen, Walter; Rose, Chris; Johnson, Chris; Huber, Craig

    2014-01-01

    The integration and deployment testing of the High Gain Antenna System for the Global Precipitation Measurement mission is summarized. The HGAS deployment mechanism is described. The gravity negation system configuration and its influence on vertical, ground-based, deployment tests are presented with test data and model predictions. A focus is made on the late discovery and resolution of a potentially mission degrading deployment interference condition. The interaction of the flight deployment mechanism, gravity negation mechanism, and use of dynamic modeling is described and lessons learned presented.

  8. Free electron laser amplifiers in the high gain Compton regime with variable wigglers

    NASA Astrophysics Data System (ADS)

    Hartzell, Kenneth R.

    1988-10-01

    We present a theoretical model of a free electron laser (FEL) in the high gain Compton regime with a variable wiggler patterned after the work of Bonifacio, Pellegrini, and Narducci for the constant wiggler configuration. This model incorporates a variable wiggler subject to the constraint ?wBw = constant where ?wBw are the spatial periodicity and field strength of the wiggler, respections of motion are numerically integrated for various spatial dependencies of the wiggler wavelength. The subsequent behavior of the radiation field relative to position and wiggler geometry is then presented, demonstrating significant improvement over the constant wiggler configuration.

  9. High Gain Antenna System Deployment Mechanism Integration, Characterization, and Lessons Learned

    NASA Technical Reports Server (NTRS)

    Parong, Fil; Russell, Blair; Garcen, Walter; Rose, Chris; Johnson, Chris; Huber, Craig

    2014-01-01

    The integration and deployment testing of the High Gain Antenna System (HGAS) for the Global Precipitation Measurement mission is summarized. The HGAS deployment mechanism is described. The gravity negation system configuration and its influence on vertical, ground-based deployment tests are presented with test data and model predictions. A focus is made on the late discovery and resolution of a potentially mission-degrading deployment interference condition. The interaction of the flight deployment mechanism, gravity-negation mechanism, and use of dynamic modeling is described and lessons learned presented

  10. High gain FEL amplification of charge modulation caused by a hadron

    SciTech Connect

    Litvinenko,V.; Ben-Zvi, I.; Hao, Y.; Kayran, D.; Pozdeyev, E.; Wang, G.; Reiche, S.; Shevchenko, O.; Vinokurov, N. A.

    2008-08-24

    In scheme of coherent electron cooling (CeC) [1,2], a modulation of electron beam density induced by a copropagation hadron is amplified in high gain FEL. The resulting amplified modulation of electron beam, its shape, form and its lethargy determine number of important properties of the coherent electron cooling. In this talk we present both analytical and numerical (using codes RON [3] and Genesis [4]) evaluations of the corresponding Green functions. We also discuss influence of electron beam parameters on the FEL response.

  11. Redesign of a Variable-Gain Output Feedback Longitudinal Controller Flown on the High-Alpha Research Vehicle (HARV)

    NASA Technical Reports Server (NTRS)

    Ostroff, Aaron J.

    1998-01-01

    This paper describes a redesigned longitudinal controller that flew on the High-Alpha Research Vehicle (HARV) during calendar years (CY) 1995 and 1996. Linear models are developed for both the modified controller and a baseline controller that was flown in CY 1994. The modified controller was developed with three gain sets for flight evaluation, and several linear analysis results are shown comparing the gain sets. A Neal-Smith flying qualities analysis shows that performance for the low- and medium-gain sets is near the level 1 boundary, depending upon the bandwidth assumed, whereas the high-gain set indicates a sensitivity problem. A newly developed high-alpha Bode envelope criterion indicates that the control system gains may be slightly high, even for the low-gain set. A large motion-base simulator in the United Kingdom was used to evaluate the various controllers. Desired performance, which appeared to be satisfactory for flight, was generally met with both the low- and medium-gain sets. Both the high-gain set and the baseline controller were very sensitive, and it was easy to generate pilot-induced oscillation (PIO) in some of the target-tracking maneuvers. Flight target-tracking results varied from level 1 to level 3 and from no sensitivity to PIO. These results were related to pilot technique and whether actuator rate saturation was encountered.

  12. High gain GaAs Photoconductive Semiconductor Switches for impulse sources

    SciTech Connect

    Loubriel, G.M.; Zutavern, F.J.; O`Malley, M.W.; Helgeson, W.D.

    1994-11-01

    A high peak power impulse pulser that is controlled with high gain, optically triggered GaAs Photoconductive Semiconductor Switches (PCSS) has been constructed and tested. The system has a short 50 {Omega} line that is charged to 100 kV and discharged through the switch when the switch is triggered with as little as 90 nJ of laser energy. We have demonstrated that the GaAs switches can be used to produce either a monocycle or a monopulse with a period or total duration of about 3 ns. For the monopulse, the voltage switched was above 100 kV, producing a peak power of about 48 MW to the 30 {Omega} load at a burst repetition rate of 1 kHz. The laser that is used is a small laser diode array whose output is delivered through a fiber to the switch. The current in the system has rise times of 430 ps and a pulse width of 1.4 ns when two laser diode arrays are used to trigger the switch. The small trigger energy and switch jitter are due to a high gain switching mechanism in GaAs.

  13. Spontaneous Raman scattering as a high-resolution XUV radiation source

    NASA Technical Reports Server (NTRS)

    Rothenberg, J. E.; Young, J. F.; Harris, S. E.

    1983-01-01

    A type of high resolution XUV radiation source is described which is based upon spontaneous anti-Stokes scattering of tunable incident laser radiation from atoms excited to metastable levels. The theory of the source is summarized and two sets of experiments using He (1s2s)(1)S atoms, produced in a CW hollow cathode and in a pulsed high power microwave discharge, are discussed. The radiation source is used to examine transitions originating from the 3p(6) shell of potassium. The observed features include four previously unreported absorption lines and several sharp interferences of closely spaced autoionizing lines. A source linewidth of about 1.9 cm(-1) at 185,000 cm(-1) is demonstrated. Previously announced in STAR as N83-18422

  14. Yb3+ doped fluorophosphate laser glasses with high gain coefficient and improved laser property

    NASA Astrophysics Data System (ADS)

    Wang, P. F.; Peng, B.; Li, W. N.; Hou, Ch. Q.; She, J. B.; Guo, H. T.; Lu, M.

    2012-04-01

    Yb3+ doped fluorophosphate glasses with high stimulated emission cross-section, large gain coefficient and low hydroxyl absorption coefficient were prepared by high temperature melting for fiber laser applications, and their spectral, general laser parameters were investigated accordingly by means of fluorescence emission spectrum, decay cure and infrared absorption spectra. Compared with previously reported fluorophosphate glasses, the investigated fluorophosphate glasses have highest grain coefficient and maintain a maximum laser systematical factor over other various types of laser glasses. The introduction of fluorides to fluorophosphate glasses results in the low level of hydroxyl absorption coefficient and concentration. All these advantages might mean that Yb3+ doped fluorophosphate glasses are a good candidate as an active laser media for short pulse, high power laser generation used for next generation nuclear fusion.

  15. High perceptual load leads to both reduced gain and broader orientation tuning.

    PubMed

    Stolte, Moritz; Bahrami, Bahador; Lavie, Nilli

    2014-01-01

    Due to its limited capacity, visual perception depends on the allocation of attention. The resultant phenomena of inattentional blindness, accompanied by reduced sensory visual cortex response to unattended stimuli in conditions of high perceptual load in the attended task, are now well established (Lavie, 2005; Lavie, 2010, for reviews). However, the underlying mechanisms for these effects remain to be elucidated. Specifically, is reduced perceptual processing under high perceptual load a result of reduced sensory signal gain, broader tuning, or both? We examined this question with psychophysical measures of orientation tuning under different levels of perceptual load in the task performed. Our results show that increased perceptual load leads to both reduced sensory signal and broadening of tuning. These results clarify the effects of attention on elementary visual perception and suggest that high perceptual load is critical for attentional effects on sensory tuning. PMID:24610952

  16. High perceptual load leads to both reduced gain and broader orientation tuning

    PubMed Central

    Stolte, Moritz; Bahrami, Bahador; Lavie, Nilli

    2014-01-01

    Due to its limited capacity, visual perception depends on the allocation of attention. The resultant phenomena of inattentional blindness, accompanied by reduced sensory visual cortex response to unattended stimuli in conditions of high perceptual load in the attended task, are now well established (Lavie, 2005; Lavie, 2010, for reviews). However, the underlying mechanisms for these effects remain to be elucidated. Specifically, is reduced perceptual processing under high perceptual load a result of reduced sensory signal gain, broader tuning, or both? We examined this question with psychophysical measures of orientation tuning under different levels of perceptual load in the task performed. Our results show that increased perceptual load leads to both reduced sensory signal and broadening of tuning. These results clarify the effects of attention on elementary visual perception and suggest that high perceptual load is critical for attentional effects on sensory tuning. PMID:24610952

  17. Technology developments and first measurements of Low Gain Avalanche Detectors (LGAD) for high energy physics applications

    NASA Astrophysics Data System (ADS)

    Pellegrini, G.; Fernández-Martínez, P.; Baselga, M.; Fleta, C.; Flores, D.; Greco, V.; Hidalgo, S.; Mandi?, I.; Kramberger, G.; Quirion, D.; Ullan, M.

    2014-11-01

    This paper introduces a new concept of silicon radiation detector with intrinsic multiplication of the charge, called Low Gain Avalanche Detector (LGAD). These new devices are based on the standard Avalanche Photo Diodes (APD) normally used for optical and X-ray detection applications. The main differences to standard APD detectors are the low gain requested to detect high energy charged particles, and the possibility to have fine segmentation pitches: this allows fabrication of microstrip or pixel devices which do not suffer from the limitations normally found [1] in avalanche detectors. In addition, a moderate multiplication value will allow the fabrication of thinner devices with the same output signal of standard thick substrates. The investigation of these detectors provides important indications on the ability of such modified electrode geometry to control and optimize the charge multiplication effect, in order to fully recover the collection efficiency of heavily irradiated silicon detectors, at reasonable bias voltage, compatible with the voltage feed limitation of the CERN High Luminosity Large Hadron Collider (HL-LHC) experiments [2]. For instance, the inner most pixel detector layers of the ATLAS tracker will be exposed to fluences up to 2×1016 1 MeV neq/cm2, while for the inner strip detector region fluences of 1×1015 neq/cm2 are expected. The gain implemented in the non-irradiated devices must retain some effect also after irradiation, with a higher multiplication factor with respect to standard structures, in order to be used in harsh environments such those expected at collider experiments.

  18. Highly nondegenerate four-wave mixing and gain nonlinearity in a strained multiple-quantum=weII optical amplifier

    E-print Network

    Park, Namkyoo

    Highly nondegenerate four-wave mixing and gain nonlinearity in a strained multiple four-wave mixing was investigated in a 1.5 pm compressively strained multi-quantum-well semiconductor traveling-wave optical amplifier at detuning frequencies up to 600 GHz. A gain nonlinearity

  19. Inflection point caustic problems and solutions for high-gain dual-shaped reflectors

    NASA Technical Reports Server (NTRS)

    Galindo-Israel, Victor; Veruttipong, Thavath; Imbriale, William; Rengarajan, Sembiam

    1990-01-01

    The singular nature of the uniform geometrical theory of diffraction (UTD) subreflector scattered field at the vicinity of the main reflector edge (for a high-gain antenna design) is investigated. It is shown that the singularity in the UTD edge-diffracted and slope-diffracted fields is due to the reflection distance parameter approaching infinity in the transition functions. While the geometrical optics (GO) and UTD edge-diffracted fields exhibit singularities of the same order, the edge slope-diffracted field singularity is more significant and is substantial for greater subreflector edge tapers. The diffraction analysis of such a subreflector in the vicinity of the main reflector edge has been carried out efficiently and accurately by a stationary phase evaluation of the phi-integral, whereas the theta-integral is carried out numerically. Computational results from UTD and physical optics (PO) analysis of a 34-m ground station dual-shaped reflector confirm the analytical formulations for both circularly symmetric and offset asymmetric subreflectors. It is concluded that the proposed PO(theta)GO(phi) technique can be used to study the spillover or noise temperature characteristics of a high-gain reflector antenna efficiently and accurately.

  20. Inflection point caustic problems and solutions for high-gain dual-shaped reflectors

    NASA Astrophysics Data System (ADS)

    Galindo-Israel, Victor; Veruttipong, Thavath; Imbriale, William; Rengarajan, Sembiam

    1990-02-01

    The singular nature of the uniform geometrical theory of diffraction (UTD) subreflector scattered field at the vicinity of the main reflector edge (for a high-gain antenna design) is investigated. It is shown that the singularity in the UTD edge-diffracted and slope-diffracted fields is due to the reflection distance parameter approaching infinity in the transition functions. While the geometrical optics (GO) and UTD edge-diffracted fields exhibit singularities of the same order, the edge slope-diffracted field singularity is more significant and is substantial for greater subreflector edge tapers. The diffraction analysis of such a subreflector in the vicinity of the main reflector edge has been carried out efficiently and accurately by a stationary phase evaluation of the phi-integral, whereas the theta-integral is carried out numerically. Computational results from UTD and physical optics (PO) analysis of a 34-m ground station dual-shaped reflector confirm the analytical formulations for both circularly symmetric and offset asymmetric subreflectors. It is concluded that the proposed PO(theta)GO(phi) technique can be used to study the spillover or noise temperature characteristics of a high-gain reflector antenna efficiently and accurately.

  1. Spontaneous Raman Scattering (SRS) System for Calibrating High-Pressure Flames Became Operational

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet

    2003-01-01

    A high-performance spontaneous Raman scattering (SRS) system for measuring quantitative species concentration and temperature in high-pressure flames is now operational. The system is located in Glenn s Engine Research Building. Raman scattering is perhaps the only optical diagnostic technique that permits the simultaneous (single-shot) measurement of all major species (N2, O2, CO2, H2O, CO, H2, and CH4) as well as temperature in combustion systems. The preliminary data acquired with this new system in a 20-atm hydrogen-air (H2-air) flame show excellent spectral coverage, good resolution, and a signal-to-noise ratio high enough for the data to serve as a calibration standard. This new SRS diagnostic system is used in conjunction with the newly developed High- Pressure Gaseous Burner facility (ref. 1). The main purpose of this diagnostic system and the High-Pressure Gaseous Burner facility is to acquire and establish a comprehensive Raman-scattering spectral database calibration standard for the combustion diagnostic community. A secondary purpose of the system is to provide actual measurements in standardized flames to validate computational combustion models. The High-Pressure Gaseous Burner facility and its associated SRS system will provide researchers throughout the world with new insights into flame conditions that simulate the environment inside the ultra-high-pressure-ratio combustion chambers of tomorrow s advanced aircraft engines.

  2. A novel design for high gain lens antennas with homogeneous media

    NASA Astrophysics Data System (ADS)

    Huang, Lujun; Wang, Ziqian; Zhou, Shutong; Li, Guanhai; Ni, Bo; Wang, Xiaofang; Li, Zhifeng; Chen, Xiaoshuang; Lu, Wei

    2012-10-01

    A high gain lens antenna is designed by using a new transformation different from the discrete optical transformation. The antenna is composed of two blocks. Each block is made of homogenous and anisotropic materials, and thus can be easily achieved by metamaterial. The numerical results based on full wave simulation indicate that the antenna can be used to realize highly directive radiation beam, and the direction of radiation beam can be controlled artificially by changing the geometry parameters of the device. The electromagnetic field in the transformation region can be either stretched or compressed along both transverse and longitudinal directions by varying the geometry parameters in the virtual space while the distribution of electromagnetic field outside the antenna is little influenced. Moreover, effective medium theory is applied to realize such an antenna with isotropic materials. Also, the multi-beams antenna is investigated. It is indicated that this antenna can generate multi-collimated beams radiating at the desired angles.

  3. Design of a high-power, high-gain, 2nd harmonic, 22.848 GHz gyroklystron

    SciTech Connect

    Veale, M. [University of California, Berkeley, CA, 24720 (United States)] [University of California, Berkeley, CA, 24720 (United States); Purohit, P. [Qualcomm Technologies, Inc. USA (United States)] [Qualcomm Technologies, Inc. USA (United States); Lawson, W. [University of Maryland, College Park, MD 20742 (United States)] [University of Maryland, College Park, MD 20742 (United States)

    2013-08-15

    In this paper we consider the design of a four-cavity, high-gain K-band gyroklystron experiment for high gradient structure testing. The frequency doubling gyroklystron utilizes a beam voltage of 500 kV and a beam current of 200 A from a magnetron injection gun (MIG) originally designed for a lower-frequency device. The microwave circuit features input and gain cavities in the circular TE{sub 011} mode and penultimate and output cavities that operate at the second harmonic in the TE{sub 021} mode. We investigate the MIG performance and study the behavior of the circuit for different values of perpendicular to parallel velocity ratio (?= V{sub ?}/ V{sub z}). This microwave tube is expected to be able to produce at least 20 MW of power in 1?s pulses at a repetition rate of at least 120 Hz. A maximum efficiency of 26% and a large signal gain of 58 dB under zero-drive stable conditions were simulated for a velocity ratio equal to 1.35.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  5. A Unity Gain High Speed Buffer to Improve Signal Integrity in High Frequency Test Interface

    Microsoft Academic Search

    Iboun Taimiya Sylla; Mustapha Slamani; Bozena Kaminska

    2001-01-01

    The availability of faster electronic components allows the design of more effective and efficient test equipments. However in high-speed applications, the effect of interconnects between the tester and the device under test “DUT” introduces ringing, overshoot and timing delay problems. In this paper we present an output high speed buffer which helps to cancel the overshoot, undershoot, and ringing. The

  6. Progress in laboratory high gain ICF (inertial confinement fusion): Prospects for the future

    SciTech Connect

    Storm, E.; Lindl, J.D.; Campbell, E.M.; Bernat, T.P.; Coleman, L.W.; Emmett, J.L.; Hogan, W.J.; Hunt, J.T.; Krupke, W.F.; Lowdermilk, W.H.

    1988-01-01

    Inertial confinement fusion (ICF), a thermonuclear reaction in a small (/approximately/5 mm diameter) fuel capsule filled with a few milligrams of deuterium and tritium, has been the subject of very fruitful experimentation since the early 1970's. High gain ICF is now on the threshold of practical applications. With a Laboratory Microfusion Facility (LMF), these applications will have major implications for national defense, basic and applied science, and power production. With a driver capable of delivering about 10 MJ in a 10-ns pulse at an intensity of /approximately/3 /times/ 10/sup 14/ W/cm/sup 2/, an appropriately configured cryogenic capsule could be compressed to a density of about 200 g/cm/sup 3/ and a temperature of 3--5 keV. Under these conditions, up to 10 mg of DT could be ignited, and with a burn efficiency of about 30%, release up to 1000 MJ of fusion energy, an energy gain of about 100. A thousand megajoules is equivalent to about one quarter ton of TNT, or about 7 gallons of oil--an amount of energy tractable under laboratory conditions and potentially very useful for a variety of applications. 61 refs., 33 figs.

  7. Compact gain-switching linearly polarized high-power Yb pulse fiber laser

    NASA Astrophysics Data System (ADS)

    Wei, K. H.; Cai, S. S.; Jiang, P. P.; Hua, D. C.; Yan, Y. X.; Wu, B.; Shen, Y. H.

    2014-08-01

    A compact gain-switching pumped linearly polarized high-power Yb pulse fiber laser is experimentally demonstrated. The laser was mainly composed of a piece of polarization-maintaining (PM) Yb-doped fiber and a pair of PM FBGs. Three fiber pig-tailed laser diodes (LDs) were applied as the pump source through a (6+1)?×?1 fiber coupler and configured in a pulse-working scheme. Stable pulse operation was achieved with repetition rate up to 200?kHz, pulse duration of 120?ns and a spectral FWHM of 0.08?nm. A maximum average laser output power of 21?W was obtained at 200?kHz with respect to the pump power of 30.3?W. The polarization extinction ratio was as good as 15?dB.

  8. High-gain inverters based on WSe2 complementary field-effect transistors.

    PubMed

    Tosun, Mahmut; Chuang, Steven; Fang, Hui; Sachid, Angada B; Hettick, Mark; Lin, Yongjing; Zeng, Yuping; Javey, Ali

    2014-05-27

    In this work, the operation of n- and p-type field-effect transistors (FETs) on the same WSe2 flake is realized,and a complementary logic inverter is demonstrated. The p-FET is fabricated by contacting WSe2 with a high work function metal, Pt, which facilities hole injection at the source contact. The n-FET is realized by utilizing selective surface charge transfer doping with potassium to form degenerately doped n+ contacts for electron injection. An ON/OFF current ratio of >10(4) is achieved for both n- and p-FETs with similar ON current densities. A dc voltage gain of >12 is measured for the complementary WSe2 inverter. This work presents an important advance toward realization of complementary logic devices based on layered chalcogenide semiconductors for electronic applications. PMID:24684575

  9. A gain-of-function positive-selection expression plasmid that enables high-efficiency cloning.

    PubMed

    Prosser, Gareth A; Williams, Elsie M; Sissons, Jack A; Walmsley, Katherine E; Parker, Madeleine R; Ackerley, David F

    2015-02-01

    Directed enzyme evolution is now a routine approach to improve desirable biocatalytic properties. When only a low-throughput screen is available to detect improved variants from a mutant gene library, it is imperative that cloning efficiency be maximized during library synthesis to avoid wasting effort screening empty plasmids. To achieve this we developed pUCXKT, a gain-of-function positive selection expression vector. Insertion of genes amplified using a specialized downstream PCR primer restores key regulatory and genetic elements necessary for co-expression of a kanamycin resistance marker adjacent to the pUCXKT cloning region. We show that pUCXKT enables 100 % cloning efficiency as well as high-level expression of inserted genes. Unlike previous positive selection expression plasmids, the strategy we used to design pUCXKT is readily adaptable to different vector backbones, antibiotic marker genes, and multiple cloning regions. PMID:25257589

  10. Calibration of Gimbaled Platforms: The Solar Dynamics Observatory High Gain Antennas

    NASA Technical Reports Server (NTRS)

    Hashmall, Joseph A.

    2006-01-01

    Simple parameterization of gimbaled platform pointing produces a complete set of 13 calibration parameters-9 misalignment angles, 2 scale factors and 2 biases. By modifying the parameter representation, redundancy can be eliminated and a minimum set of 9 independent parameters defined. These consist of 5 misalignment angles, 2 scale factors, and 2 biases. Of these, only 4 misalignment angles and 2 biases are significant for the Solar Dynamics Observatory (SDO) High Gain Antennas (HGAs). An algorithm to determine these parameters after launch has been developed and tested with simulated SDO data. The algorithm consists of a direct minimization of the root-sum-square of the differences between expected power and measured power. The results show that sufficient parameter accuracy can be attained even when time-dependent thermal distortions are present, if measurements from a pattern of intentional offset pointing positions is included.

  11. Monoclinic m-LaVO4—a novel high Raman gain SRS-active crystal

    NASA Astrophysics Data System (ADS)

    Kaminskii, A. A.; Yu, H.; Zhang, H.; Wang, J.; Lux, O.; Rhee, H.; Eichler, H. J.; Yoneda, H.; Shirakawa, A.; Zhang, J.; Tang, G.

    2014-12-01

    Monoclinic m-LaVO4, having a monazite-type structure and being known as a host crystal for Nd3+-lasants, is an attractive ?(3)-nonlinear optical material for Raman laser converters. This paper presents the stimulated Raman scattering (SRS) spectroscopy of m-LaVO4 in the visible and near-IR spectral range using picosecond laser excitation. High-order SRS and Raman-induced four-wave parametric mixing processes result in an almost two-octave-wide Stokes and anti-Stokes frequency comb. All the measured spectral lines were assigned to the participating molecular vibration modes of the studied vanadate. Finally, an estimation of the steady-state Raman gain coefficient for first Stokes generation in near-IR was performed.

  12. High-resolution MR imaging of periarterial edema associated with biological inflammation in spontaneous carotid dissection.

    PubMed

    Naggara, Olivier; Touzé, Emmanuel; Marsico, Rodolpho; Leclerc, Xavier; Nguyen, Thanh; Mas, Jean-Louis; Pruvo, Jean-Pierre; Meder, Jean-François; Oppenheim, Catherine

    2009-09-01

    It has been suggested that spontaneous cervical carotid artery dissection (sCAD) may result from arterial inflammation. Periarterial edema (PAE), occasionally described in the vicinity of the mural hematoma in patients with sCAD, may support this hypothesis. Using cervical high-resolution magnetic resonance imaging, three readers, blinded to the mechanism of carotid artery dissection, searched for PAE, defined as periarterial T2-hyperintensity and T1-hypointensity, in 29 consecutive CAD patients categorized as spontaneous CAD (sCAD, n = 18) or traumatic CAD (tCAD, n = 11; i.e., major head or neck trauma within 2 weeks before the clinical onset). The relationships between PAE, inflammatory biological markers, history of infection and CAD mechanism were explored. Multiple CADs (n = 8) were found only in sCAD patients. Compared with tCAD, patients with sCAD were more likely to have a recent history of infection (OR = 12.5 [(95%)CI = 1.3-119], p = 0.03), PAE (83% vs. 27%; OR = 13.3 [(95%)CI = 2.2-82.0], p = 0.005) and to have elevated CRP (OR = 6.1 [(95%)CI = 1.2-32.1], p = 0.0002) or ESR (OR = 8.8 [(95%)CI = 1.5-50.1], p = 0.002) values. Interobserver agreement was 0.84 or higher for PAE identification. sCAD was associated with PAE and biological inflammation. Our results support the hypothesis of an underlying arterial inflammation in sCAD. PMID:19396444

  13. Fructose-induced leptin resistance exacerbates weight gain in response to subsequent high-fat feeding

    NSDL National Science Digital Library

    Alexandra Shapiro (University of Florida Pharmacology and Therapeutics)

    2008-08-16

    It has been suggested that increased fructose intake is associated with obesity. We hypothesized that chronic fructose consumption causes leptin resistance, which subsequently may promote the development of obesity in response to a high fat diet. Sprague-Dawley rats were fed a fructose-free control or 60% fructose diet for six months and then tested for leptin resistance. Half of the rats in each group were then switched to high fat diet for two weeks, while the other half continued on their respective diets. Chronic fructose consumption caused leptin resistance while serum leptin levels, weight and adiposity were the same as in control rats that were leptin responsive. Intraperitoneal leptin injections reduced 24-hour food intake in fructose-free group (73.7 ± 6.3 vs 58.1 ± 8 kcal, p=0.02), but had no effect in fructose-fed rats (71.2 ± 6.6 vs 72.4 ± 6.4 kcal, p=0.9). Absence of anorexic response to intraperitoneal leptin injection was associated with 25.7% decrease in hypothalamic signal transducer and activator of transcription 3 (STAT3) phosphorylation in the high-fructose fed rats compared with controls (p=0.015). Subsequent exposure of the fructose-mediated leptin-resistant rats to a high fat diet lead to exacerbated weight gain (50.2 ± 2 g) compared with correspondingly fed leptin-responsive animals that were pre-treated with the fructose-free diet (30.4 ± 5.8 g, p= 0.012). Our data indicate that chronic fructose consumption induces leptin resistance prior to body weight, adiposity, serum leptin, insulin or glucose increases, and this fructose-induced leptin resistance accelerates high fat induced obesity

  14. Influence of statistical gain fluctuations of the high-frequency amplifier on the sensitivity of a Dicke-Radiometer

    Microsoft Academic Search

    Andreas Magun; Klaus Künzi

    1971-01-01

    The influence of statistical gain fluctuations of the high-frequency amplifier on the sensitivity of a Dicke radiometer with selective videoamplifier is calculated with methods that are used in describing random processes. It is shown that the radiometer sensitivity depends on the power density spectrumSg(f) of the gain fluctuations for a Dicke-radiometer of the zero-balanced as well as the unbalanced type.

  15. High-gain harmonic generation of soft X-rays with the `fresh bunch` technique

    SciTech Connect

    Yu, Li-Hua; Ben-Zvi, I.

    1996-10-01

    We report numerical simulations (using the TDA code) and analytic verification of the generation of 64 {Angstrom} high power soft X- rays from an exponential regime single pass seeded FEL. The seed is generated in the FEL using the High Gain Harmonic Generation (HGHG) technique combined with the `Fresh bunch` technique. A seed pulse at 2944 {Angstrom} is generated by conventional laser techniques. The seed pulse produces an intense energy modulation of the rear part of a I GeV, 1245 {Angstrom} electron beam in a `modulator` wiggler. In the `radiator` wiggler, (resonant to 64 {Angstrom}), the energy modulation creates beam density modulation followed by radiation of the 46{sup th} harmonic of the seed. We use a magnetic delay to position the 64 A{Angstrom} radiation at the undisturbed front of the bunch to serve as a seed for a single pass, exponential growth FEL. After a 9 m long exponential section followed by a 7 m long tapered section the radiation power reaches 3.3 GW.

  16. A Current Balancing Instrumentation Amplifier (CBIA) Bioamplifier with High Gain Accuracy

    E-print Network

    Dwobeng, Ebenezer

    2012-02-14

    of the closed loop system for differential signals Avd is given by Avd R2 R1 1 1 A 1 R2 R1 (2.1) For large open loop gain (A), the gain of the feedback system approaches the resistor or capacitor ratio R2 R1 . However increasing...

  17. Commensal E. coli Stx2 lysogens produce high levels of phages after spontaneous prophage induction

    PubMed Central

    Iversen, Hildegunn; L' Abée-Lund, Trine M.; Aspholm, Marina; Arnesen, Lotte P. S.; Lindbäck, Toril

    2015-01-01

    Enterohemorrhagic E. coli (EHEC) is a food-borne pathogen that causes disease ranging from uncomplicated diarrhea to life-threatening hemolytic uremic syndrome (HUS) and nervous system complications. Shiga toxin 2 (Stx2) is the major virulence factor of EHEC and is critical for development of HUS. The genes encoding Stx2 are carried by lambdoid bacteriophages and the toxin production is tightly linked to the production of phages during lytic cycle. It has previously been suggested that commensal E. coli could amplify the production of Stx2-phages and contribute to the severity of disease. In this study we examined the susceptibility of commensal E. coli strains to the Stx2-converting phage ?734, isolated from a highly virulent EHEC O103:H25 (NIPH-11060424). Among 38 commensal E. coli strains from healthy children below 5 years, 15 were lysogenized by the ?734 phage, whereas lytic infection was not observed. Three of the commensal E. coli ?734 lysogens were tested for stability, and appeared stable and retained the phage for at least 10 cultural passages. When induced to enter lytic cycle by H2O2 treatment, 8 out of 13 commensal lysogens produced more ?734 phages than NIPH-11060424. Strikingly, five of them even spontaneously (non-induced) produced higher levels of phage than the H2O2 induced NIPH-11060424. An especially high frequency of HUS (60%) was seen among children infected by NIPH-11060424 during the outbreak in 2006. Based on our findings, a high Stx2 production by commensal E. coli lysogens cannot be ruled out as a contributor to the high frequency of HUS during this outbreak. PMID:25692100

  18. Design and performance of an Automatic Gain Control system for the High Energy X-Ray Timing Experiment

    NASA Technical Reports Server (NTRS)

    Pelling, Michael R.; Rothschild, Richard E.; Macdonald, Daniel R.; Hertel, Robert; Nishiie, Edward

    1991-01-01

    The High Energy X-Ray Timing Experiment (HEXTE), currently under development for the X-Ray Timing Explorer (XTE) mission, employs a closed loop gain control system to attain 0.5 percent stabilization of each of eight-phoswich detector gains. This Automatic Gain Control (AGC) system utilizes a split window discriminator scheme to control the response of each detector pulse height analyzer to gated Am-241 X-ray events at 60 keV. A prototype AGC system has been implemented and tested within the gain perturbation environment expected to be experienced by the HEXTE instrument in flight. The AGC system and test configuration are described. Response, stability and noise characteristics are measured and compared with theoretical predictions. The system is found to be generally suitable for the HEXTE application.

  19. High-gain AlGaAs/GaAs double heterojunction Darlington phototransistors for optical neural networks

    NASA Technical Reports Server (NTRS)

    Kim, Jae H. (inventor); Lin, Steven H. (inventor)

    1991-01-01

    High-gain MOCVD-grown (metal-organic chemical vapor deposition) AlGaAs/GaAs/AlGaAs n-p-n double heterojunction bipolar transistors (DHBTs) and Darlington phototransistor pairs are provided for use in optical neural networks and other optoelectronic integrated circuit applications. The reduced base doping level used results in effective blockage of Zn out-diffusion, enabling a current gain of 500, higher than most previously reported values for Zn-diffused-base DHBTs. Darlington phototransitor pairs of this material can achieve a current gain of over 6000, which satisfies the gain requirement for optical neural network designs, which advantageously may employ neurons comprising the Darlington phototransistor pairs in series with a light source.

  20. A MMI-based ultra-linear high-gain modulator and its performance analysis

    NASA Astrophysics Data System (ADS)

    Yue, P.; Mao, B. M.; Yi, X.; Li, Q. N.; Liu, Z. J.

    2013-12-01

    An electric optical modulator including a 1×2 multimode interference (MMI) coupler and an integrated Mach-Zehnder Interferometer (MZI) modulator that consists of a microring and a Phase Modulator (PM) is suggested in this paper. Such a modulator can achieve large output RF gain and high linearity performance at the same time. Moreover, due to the application of MMI coupler, traditional direct current (DC) bias circuits can be omitted and the modulator's deterioration caused by the phase error can be decreased a lot, which leads to reduced device complexity and increased device stability. The presented numerical and simulation results confirm the advantages of the newly proposed modulator over conventional modulators (MZI, RAMZI and IMPACC). Further analysis manifests that the proposed modulator has good tolerance in two aspects. Firstly, the modulator has an inherent ability to mitigate the detrimental effects of microring waveguide loss on slope efficiency and linearity by simply adjusting the external RF power split ratio. Secondly, the application of the MMI device increases the modulator's tolerance for the phase deviation caused by some environmental factors.

  1. A Modified Lunar Reconnaissance Orbiter (LRO) High Gain Antenna (HGA) Controller Based on Flight Performance

    NASA Technical Reports Server (NTRS)

    Shah, Neerav

    2010-01-01

    The National Aeronautics and Space Administration's (NASA) Lunar Reconnaissance Orbiter (LRO) was launched on June 18, 2009 and is currently in a 50 km mean altitude polar orbit around the Moon. LRO was designed and built by the NASA Goddard Space Flight Center in Greenbelt, MD. The spacecraft is three-axis stabilized via the attitude control system (ACS), which is composed of various control modes using different sets of sensors and actuators. In addition to pointing the spacecraft, the ACS is responsible for pointing LRO s two appendages, the Solar Array (SA) and the High Gain Antenna (HGA). This study reviews LRO s HGA control system. Starting with an overview of the HGA system, the paper delves into the single input single output (SISO) linear analysis followed by the controller design. Based on flight results, an alternate control scheme is devised to address inherent features in the flight control system. The modified control scheme couples the HGA loop with the spacecraft pointing control loop, and through analysis is shown to be stable and improve transient performance. Although proposed, the LRO project decided against implementing this modification.

  2. Microlens array-based high-gain screen design for direct projection head-up displays.

    PubMed

    Hedili, M Kivanc; Freeman, Mark O; Urey, Hakan

    2013-02-20

    Head-up display (HUD) systems have been used in recent car models to provide essential information to the drivers while keeping their eyes on the road. Virtual image HUD systems have been the preferred method, but they have the drawback of requiring a large volume of space in order to accommodate the relay optics that creates the virtual image. This is especially significant as the desired field of view increases. Direct projection HUD systems have been developed with a separate stand-alone microlens array (MLA)-based transparent screen on the dashboard, offering a compact solution. In this paper, we propose a direct projection HUD system based on a unique, windshield-embedded see-through screen that uses minimal space under the dashboard, offering an elegant and compact solution to the HUD problem. The screen is based on MLAs with varying surface normal angles such that the light from the projector is directed to the viewer's eyes from all positions across the field of view. Varying tilts provide an efficient relay and high brightness even with a low-lumen output projector. The calculated screen gain is about 69 and the eyebox area is about 30 cm×30 cm. PMID:23435009

  3. Angular multiplexing as a technique for short-pulse amplification in a high-gain xenon amplifier

    Microsoft Academic Search

    Robert P. Sandoval

    1978-01-01

    It has been proposed that the technique of angular multiplexing could provide an efficient scheme for extracting short pulses from a high-gain laser with a high degree of spatial and temporal control of the extracted laser beam. The scheme of angular multiplexing proposes to amplify short laser pulses (?1 nsec) by sequentially passing these pulses through the amplifier at slightly

  4. Progress towards a high-gain and robust target design for heavy ion fusion

    SciTech Connect

    Henestroza, Enrique; Grant Logan, B. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2012-07-15

    Recently [E. Henestroza et al., Phys. Plasmas 18, 032702 (2011)], a new inertial-fusion target configuration, the X-target, using one-sided axial illumination has been explored. This class of target uses annular and solid-profile heavy ion beams to compress and ignite deuterium-tritium (DT) fuel that fills the interior of metal cases that have side-view cross sections in the shape of an 'X.' X-targets using all-DT-filled metal cases imploded by three annular ion beams resulted in fuel densities of {approx}50 g/cm{sup 3} at peak compression, and fusion gains of {approx}50, comparable to heavy ion driven hohlraum targets [D. A. Callahan-Miller and M. Tabak, Phys. Plasmas 7, 2083 (2000)]. This paper discusses updated X-target configurations that incorporate inside the case a propellant (plastic) and a pusher (aluminum) surrounding the DT fuel. The updated configurations are capable of assembling higher fuel areal densities {approx}2 g/cm{sup 2} using two annular beams to implode the target to peak DT densities {approx}100 g/cm{sup 3}, followed by a fast-ignition solid ion beam which heats the high-density fuel to thermonuclear temperatures in {approx}200 ps to start the burn propagation, obtaining gains of {approx}300. These targets have been modeled using the radiation-hydrodynamics code HYDRA [M. M. Marinak et al., Phys. Plasmas 8, 2275 (2001)] in two- and three- dimensions to study the properties of the implosion as well as the ignition and burn propagation phases. At typical Eulerian mesh resolutions of a few microns, the aluminum-DT interface shows negligible Rayleigh-Taylor (RT) and Richtmyer-Meshkov instability growth; also, the shear flow of the DT fuel as it slides along the metal X-target walls, which drives the RT and Kelvin Helmholtz instabilities, does not have a major effect on the burning rate. An analytic estimate of the RT instability process at the Al-DT interface shows that the aluminum spikes generated during the pusher deceleration phase would not reach the ignition zone in time to affect the burning process. Also, preliminary HYDRA calculations, using a higher resolution mesh to study the shear flow of the DT fuel along the X-target walls, indicate that metal-mixed fuel produced near the walls would not be transferred to the DT ignition zone (at maximum {rho}R) located at the vertex of the X-target.

  5. High spatial resolution BOTDA using simultaneously launched gain and loss pump pulses

    NASA Astrophysics Data System (ADS)

    Motil, A.; Danon, O.; Peled, Y.; Tur, M.

    2013-05-01

    We report a 10cm spatial resolution in a Brillouin-based distributed sensing system using two simultaneously launched gain and loss pump pulses, having slightly different durations. Post-recording subtraction of the probe signal, excited by the shorter pulse, from the corresponding one, obtained from the longer pump pulse, is no longer required, since it is done automatically by the overlapping parts of the gain and loss pump pulses. Using a 30ns gain pump pulse and a 29ns loss pump pulse we were able to improve upon previously published results, achieving a distributed strain measurement along a standard single mode optical fiber with a spatial resolution of ~10cm. This technique does not broaden the involved Brillouin gain spectra so that the strain/temperature sensitivity is not compromised.

  6. High-rate pacing-induced atrial fibrillation effectively reveals properties of spontaneously occurring paroxysmal atrial fibrillation in humans

    PubMed Central

    Calvo, David; Atienza, Felipe; Jalife, José; Martínez-Alzamora, Nieves; Bravo, Loreto; Almendral, Jesús; González-Torrecilla, Esteban; Arenal, Ángel; Bermejo, Javier; Fernández-Avilés, Francisco; Berenfeld, Omer

    2012-01-01

    Aims Research on paroxysmal atrial fibrillation (AF) assumes that fibrillation induced by rapid pacing adequately reproduces spontaneously occurring paroxysmal AF in humans. We aimed to compare the spectral properties of spontaneous vs. induced AF episodes in paroxysmal AF patients. Methods and results Eighty-five paroxysmal AF patients arriving in sinus rhythm to the electrophysiology laboratory were evaluated prior to ablation. Atrial fibrillation was induced by rapid pacing from the pulmonary vein-left atrial junctions (PV-LAJ), the coronary sinus (CS), or the high right atrium (HRA). Simultaneous recordings were obtained using multipolar catheters. Off-line power spectral analysis of 5 s bipolar electrograms was used to determine dominant frequency (DF) at recording sites with regularity index >0.2. Sixty-eight episodes were analysed for DF. Comparisons were made between spontaneous (n= 23) and induced (n= 45) AF episodes at each recording site. No significant differences were observed between spontaneous and induced AF episodes in HRA (5.18 ± 0.69 vs. 5.06 ± 0.91 Hz; P= 0.64), CS (5.27 ± 0.69 vs. 5.36 ± 0.76 Hz; P= 0.69), or LA (5.72 ± 0.88 vs. 5.64 ± 0.75 Hz; P= 0.7) regardless of pacing site. Consistent with these results, paired analysis in seven patients with both spontaneous and induced AF episodes, showed no regional DFs differences. Moreover, a left-to-right DF gradient was also present in both spontaneous (PV-LAJ 5.71 ± 0.81 vs. HRA 5.18 ± 0.69 Hz; P= 0.005) and induced (PV-LAJ 5.62 ± 0.72 vs. HRA 5.07 ± 0.91 Hz; P= 0.002) AF episodes, with no differences between them (P= not specific). Conclusion In patients with paroxysmal AF, high-rate pacing-induced AF adequately mimics spontaneously initiated AF, regardless of induction site. PMID:22696516

  7. Interval Mapping of High Growth (Hg), a Major Locus That Increases Weight Gain in Mice

    PubMed Central

    Horvat, S.; Medrano, J. F.

    1995-01-01

    The high growth locus (hg) causes a major increase in weight gain and body size in mice. As a first step to map-based cloning of hg, we developed a genetic map of the hg-containing region using interval mapping of 403 F(2) from a C57BL/6J-hghg X CAST/EiJ cross. The maximum likelihood position of hg was at the chromosome 10 marker D10Mit41 (LOD = 24.8) in the F(2) females and 1.5 cM distal to D10Mit41 (LOD = 9.56) in the F(2) males with corresponding LOD 2 support intervals of 3.7 and 5.4 cM, respectively. The peak LOD scores were significantly higher than the estimated empirical threshold LOD values. The localization of hg by interval mapping was supported by a test cross of F(2) mice recombinant between the LOD 2 support interval and the flanking marker. The interval mapping and test-cross results indicate that hg is not allelic with candidate genes Igf1 or decorin (Dcn), a gene that was mapped close to hg in this study. The hg inheritance was recessive in females, although we could not reject recessive or additive inheritance in males. Possible causes for sex differences in peak LOD scores and for the distortion of transmission ratios observed in F(2) males are discussed. The genetic map of the hg region will facilitate further fine mapping and cloning of hg, and allow searches for a homologous quantitative trait locus affecting growth in humans and domestic animals. PMID:7789774

  8. Verification of the Solar Dynamics Observatory High Gain Antenna Pointing Algorithm Using Flight Data

    NASA Technical Reports Server (NTRS)

    Bourkland, Kristin L.; Liu, Kuo-Chia

    2011-01-01

    The Solar Dynamics Observatory (SDO), launched in 2010, is a NASA-designed spacecraft built to study the Sun. SDO has tight pointing requirements and instruments that are sensitive to spacecraft jitter. Two High Gain Antennas (HGAs) are used to continuously send science data to a dedicated ground station. Preflight analysis showed that jitter resulting from motion of the HGAs was a cause for concern. Three jitter mitigation techniques were developed and implemented to overcome effects of jitter from different sources. These mitigation techniques include: the random step delay, stagger stepping, and the No Step Request (NSR). During the commissioning phase of the mission, a jitter test was performed onboard the spacecraft, in which various sources of jitter were examined to determine their level of effect on the instruments. During the HGA portion of the test, the jitter amplitudes from the single step of a gimbal were examined, as well as the amplitudes due to the execution of various gimbal rates. The jitter levels were compared with the gimbal jitter allocations for each instrument. The decision was made to consider implementing two of the jitter mitigating techniques on board the spacecraft: stagger stepping and the NSR. Flight data with and without jitter mitigation enabled was examined, and it is shown in this paper that HGA tracking is not negatively impacted with the addition of the jitter mitigation techniques. Additionally, the individual gimbal steps were examined, and it was confirmed that the stagger stepping and NSRs worked as designed. An Image Quality Test was performed to determine the amount of cumulative jitter from the reaction wheels, HGAs, and instruments during various combinations of typical operations. The HGA-induced jitter on the instruments is well within the jitter requirement when the stagger step and NSR mitigation options are enabled.

  9. Interval mapping of high growth (hg), a major locus that increases weight gain in mice

    SciTech Connect

    Horvat, S.; Medrano, J.F. [Univ. of California, Davis, CA (United States)

    1995-04-01

    The high growth locus (hg) causes a major increase in weight gain and body size in mice. As a first step to map-based cloning of hg, we developed a genetic map of the hg-containing region using interval mapping of 403 F{sub 2} from a C57BL/6J-hghg x CAST/EiJ cross. The maximum likelihood position of hg was at the chromosome 10 marker D10Mit41 (LOD = 24.8) in the F{sub 2} females and 1.5 cM distal to D10Mit41 (LOD = 9.56) in the F{sub 2} males with corresponding LOD 2 support intervals of 3.7 and 5.4 cM, respectively. The peak LOD scores were significantly higher than the estimated empirical threshold LOD values. The localization of hg by interval mapping was supported by a test cross of F{sub 2} mice recombinant between the LOD 2 support interval and the flanking marker. The interval mapping and test-cross indicate that hg is not allelic with candidate genes Igf1 or decorin (Dcn), a gene that was mapped close to hg in this study. The hg inheritance was recessive in females, although we could not reject recessive or additive inheritance in males. Possible causes for sex differences in peak LOD scores and for the distortion of transmission ratios observed in F{sub 2} males are discussed. The genetic map of the hg region will facilitate further fine mapping and cloning of hg, and allow searches for a homologous quantitative trait locus affecting growth in humans and domestic animals. 48 refs., 3 figs., 3 tabs.

  10. Factors influencing individual variability in high fat diet-induced weight gain in out-bred MF1 mice.

    PubMed

    Vaanholt, L M; Sinclair, R E; Mitchell, S E; Speakman, J R

    2015-05-15

    Easy access to high-energy palatable foods has been suggested to have contributed to the world-wide obesity epidemic. However, within these 'obesogenic' environments many people manage to remain lean. Mice also show variability in their weight gain responses to high-fat diet (HFD) feeding and their weight loss responses to calorically restricted (CR) feeding. In this study we investigated which factors contribute to determining susceptibility to HFD-induced obesity in mice, and whether the responses in weight gain on HFD are correlated with the responses to CR. One-hundred twenty four mice were exposed to 30% CR for 28days followed by a 14day recovery period, and subsequent exposure to 60% HFD for 28days. Responses in various metabolic factors were measured before and after each exposure (body mass; BM, body composition, food intake; FI, resting metabolic rate; RMR, physical activity, body temperature and glucose tolerance; GT). Weight changes on HFD ranged from -1 to 26%, equivalent to -0.2g to 10.5g in absolute mass. Multiple regression models showed that fat free mass (FFM) of the mice before exposure to HFD predicted 12% of the variability in weight gain on HFD (p<0.001). Also, FI during the first week of HFD feeding predicted 20% of the variability in BM and fat mass (FM) gain 4weeks later. These data may point to a role for the reward system in driving individual differences in FI and weight gain. Weight gain on the HFD was significantly negatively correlated to weight loss on CR, indicating that animals that are poor at defending against weight gain on HFD, were also poor at defending against CR-induced weight loss. Changes in FM and FFM in response to HFD or CR were not correlated however. PMID:25817538

  11. High mobility polymer based on a ?-extended benzodithiophene and its application for fast switching transistor and high gain photoconductor

    PubMed Central

    Park, Sungmin; Lim, Byung Tack; Kim, BongSoo; Son, Hae Jung; Chung, Dae Sung

    2014-01-01

    Here we present synthesis and electronic properties of a new alternating copolymer composed of dithieno[2,3-d;2?,3?-d?]benzo[1,2-b;4,5-b?]dithiophene (DTBDT) and diketopyrrolopyrrole units, poly dithienobenzodithiophene-co-diketopyrrolopyrrolebithiophene (PDPDBD). The resulting polymer showed hysteresis free, fast switching and highly reliable organic thin-film transistor properties comparable to a-Si. Hole mobility of the polymer is about 2.7?cm2V?1s?1, which is remarkably improved compared with its benzodithiophene (BDT)-analougue that contains a smaller aromatic ring of BDT in the place of DTBDT. This is mainly due to much increased intramolecular charge transport originated from PDPDBD's rigid molecular backbone. Furthermore, photoconductor devices fabricated by using PDPDBD as an active layer showed a high performance with the highest photoconductive gain of ~105. Taken together, the successful PDPDBD's transistor and photoconductor performances with high device stability demonstrated practical applicability of PDPDBD in low-cost and flexible optoelectronic devices. PMID:24970637

  12. Single stage high voltage gain boost converter with voltage Multiplier Cells for battery charging using photovoltaic panels

    Microsoft Academic Search

    Luiz H. S. C. Barreto; Paulo P. Praca; Gustavo A. L. Henn; Ranoyca N. A. L. Silva; Demercil S. Oliveira

    2012-01-01

    This paper presents a non-isolated high frequency DC-DC converter, which integrates a battery charger, photovoltaic panels, and a high voltage gain boost converter in a single conversion stage with soft-switching characteristic. The proposed topology uses voltage Multiplier Cells (MCs), leading do high voltage step-up. Also, the bidirectional behavior admits the DC bus to be generated via battery bank, or photovoltaic

  13. Investigation Into the Effects of the Patch-Type FSS Superstrate on the High-Gain Cavity Resonance Antenna Design

    Microsoft Academic Search

    Alireza Foroozesh; Lotfollah Shafai

    2010-01-01

    Results of modeling, design, simulation and fabrication are presented for a high-gain cavity resonance antenna (CRA), employing highly-reflective patch-type superstrates. In order to determine the resonant conditions, the antenna is first analyzed using the transverse equivalent network (TEN) model, as well as the well known simple ray-tracing method. Prior to that, a highly-reflective patch-type frequency selective surface (FSS) is designed

  14. Verbal Marking of Affect by Children with Asperger Syndrome and High Functioning Autism during Spontaneous Interactions with Family Members

    Microsoft Academic Search

    Eve Müller; Adriana Schuler

    2006-01-01

    Verbal marking of affect by older children with Asperger Syndrome (AS) and high functioning autism (HFA) during spontaneous\\u000a interactions is described. Discourse analysis of AS and HFA and typically developing children included frequency of affective\\u000a utterances, affective initiations, affective labels and affective explanations, attribution of affective responses to self\\u000a and others, and positive and negative markers of affect. Findings indicate

  15. High-Gain, Direct-Drive Foam Target Designs for the National Ignition Facility

    SciTech Connect

    Collins, T.J.B.; Skupsky, S.; Goncharov, V. N.; Betti, R.; McKenty, P.W.; Radha, P.B.; Epstein, R.; Poludnonko,A.; Frank, A.; Mitran, S.

    2004-08-02

    Initial designs for direct-drive targets for the National Ignition Facility had a one-dimensional (1-D) gain of 45. A pure cryogenic DT shell with the fuel set on a = 3 adiabat was used to provide adequate hydrodynamic stability. One-dimensional calculations indicate that a gain of over 80 may be acheived through the use of an outer layer of foam wetted by cryogenic deuterium and tritium (DT). The presence of higher-Z absorbers (C) in the foam increases the absorbed energy, allowing the target to contain more fuel.

  16. High energy gain in three-dimensional simulations of light sail acceleration

    SciTech Connect

    Sgattoni, A., E-mail: andrea.sgattoni@polimi.it [Dipartimento di Energia, Politecnico di Milano, Milano (Italy); CNR, Istituto Nazionale di Ottica, u.o.s. “Adriano Gozzini,” Pisa (Italy); Sinigardi, S. [CNR, Istituto Nazionale di Ottica, u.o.s. “Adriano Gozzini,” Pisa (Italy); Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna (Italy); INFN sezione di Bologna, Bologna (Italy); Macchi, A. [CNR, Istituto Nazionale di Ottica, u.o.s. “Adriano Gozzini,” Pisa (Italy); Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Pisa (Italy)

    2014-08-25

    The dynamics of radiation pressure acceleration in the relativistic light sail regime are analysed by means of large scale, three-dimensional (3D) particle-in-cell simulations. Differently to other mechanisms, the 3D dynamics leads to faster and higher energy gain than in 1D or 2D geometry. This effect is caused by the local decrease of the target density due to transverse expansion leading to a “lighter sail.” However, the rarefaction of the target leads to an earlier transition to transparency limiting the energy gain. A transverse instability leads to a structured and inhomogeneous ion distribution.

  17. A 12-dB high-gain monolithic distributed amplifier

    NASA Astrophysics Data System (ADS)

    Larue, Ross A.; Bandy, Steve G.; Zdasiuk, George A.

    1986-12-01

    By reducing gate and drain line loss associated with the active elements of a distributed amplifier, significant gain improvements are possible. Loss reduction is achieved in a novel monolithic distributed amplifier by replacing the common-source FET's of the conventional design with cascode elements having a gate length of one-quarter micron. A record gain of over 10 dB from 2 to 18 GHz and a noise figure of 4 dB at 7 GHz have been achieved on a working amplifier. Details of the design and fabrication process are described.

  18. Two-color operation in high-gain free-electron lasers

    PubMed

    Freund; O'Shea

    2000-03-27

    Two-color operation in free-electron laser (FEL) amplifiers is studied using a 3D nonlinear polychromatic simulation. We assume the FEL is seeded at two closely spaced wavelengths within the gain band, and study the growth of the seeds and a discrete spectrum of beat waves that are outside the gain band. The beat waves grow parasitically due to electron bunching in the seeded waves with growth rates higher than the seeded waves. Injection of narrow-band seeds ensures a discrete spectrum. An example is discussed corresponding to an x-ray FEL; however, the physics is applicable to all spectral ranges. PMID:11018961

  19. Pulse code modulation of a gain-switched LD and its application to a high-speed electrooptical time multiplexer

    Microsoft Academic Search

    Keishi Habara; Katsuaki Kikuchi

    1987-01-01

    This paper describes the direct pulse code modulation (PCM) method of a gain-switched LD and its application to a high-speed electrooptical time division multiplexer. The method can effectively remove the PCM pattern effect. An experimental modulation is demonstrated at a repetition rate of 1 GHz. Also discussed is a 4 × 1 electrooptical time division multiplexer operating in the multigigabit

  20. EFFECTS OF PREVIOUS LIVEWEIGHT GAIN ON VISCERAL ORGAN MASS AND OXYGEN CONSUMPTION IN CATTLE DUING HIGH-GRAIN FEEDING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Forty-eight fall-weaned crossbred steers (231+/-25 kg) were used in a completely random design to determine the effect of previous liveweight gain on visceral organ mass and oxygen consumption. During the 143-d growing phase, treatments were high (HGW; 1.28 kg/d) or low (LGW; .48 kg/d) daily BW gai...

  1. Realising high-current gain p-n-p transistors using a novel surface accumulation layer transistor

    E-print Network

    Kumar, M. Jagadesh

    Realising high-current gain p-n-p transistors using a novel surface accumulation layer transistor accumulation layer transistor (SALTran) on SOI, which uses the concept of surface accumulation of holes near of the previously published conventional p-n-p lateral bipolar transistor (LBT) structure. From the simulation

  2. The New Horizons high gain antenna: reflector design for a spin-stabilized bus at cryogenic temperatures

    Microsoft Academic Search

    R. C. Schulze; S. Hill

    2004-01-01

    The New Horizons antenna system is subjected to cryogenic temperatures during the Pluto and KBO encounters. The RF performance of the high gain antenna (HGA) during and after these encounters is critical for the science and communications mission requirements. In order to satisfy these requirements, the angular alignment of the HGA bore-site and spacecraft spin axis must be maintained within

  3. Modelling Plant and Soil Nitrogen Feedbacks Affecting Forest Carbon Gain at High CO2

    NASA Astrophysics Data System (ADS)

    McMurtrie, R. E.; Norby, R. J.; Franklin, O.; Pepper, D. A.

    2007-12-01

    Short-term, direct effects of elevated atmospheric CO2 concentrations on plant carbon gain are relatively well understood. There is considerable uncertainty, however, about longer-term effects, which are influenced by various plant and ecosystem feedbacks. A key feedback in terrestrial ecosystems occurs through changes in plant carbon (C) allocation patterns. For instance, if high CO2 were to increase C allocation to roots, then plants may experience positive feedback through improved plant nutrition. A second type of feedback, associated with decomposition of soil-organic matter, may reduce soil-nutrient availability at high CO2. This paper will consider mechanistic models of both feedbacks. Effects of high CO2 on plant C allocation will be investigated using a simple model of forest net primary production (NPP) that incorporates the primary mechanisms of plant carbon and nitrogen (N) balance. The model called MATE (Model Any Terrestrial Ecosystem) includes an equation for annual C balance that depends on light- saturated photosynthetic rate and therefore on [CO2], and an equation for N balance incorporating an expression for N uptake as a function of root mass. The C-N model is applied to a Free Air CO2 Exchange (FACE) experiment at Oak Ridge National Laboratory (ORNL) in Tennessee, USA, where closed-canopy, monoculture stands of the deciduous hardwood sweetgum ( Liquidambar styraciflua) have been growing at [CO2] of 375 and 550 ppm for ten years. Features of this experiment are that the annual NPP response to elevated CO2 has averaged approximately 25% over seven years, but that annual fine-root production has almost doubled on average, with especially large increases in later years of the experiment (Norby et al. 2006). The model provides a simple graphical approach for analysing effects of elevated CO2 and N supply on leaf/root/wood C allocation and productivity. It simulates increases in NPP and fine-root production at the ORNL FACE site that are consistent with experimental measurements. Increased below-ground C allocation has been observed at other forest high-CO2 experiments including the Duke FACE and Flakaliden experiments in North Carolina, USA, and Sweden, respectively. This result is predicted by MATE, but not by biogeochemical-cycling models such as our plant-soil model G'DAY (Generic Decomposition And Yield), which predicts instead that a positive CO2 response will enhance litter quantity, and hence will increase soil N immobilisation and reduce the pool of N available for plant uptake (Pepper et al. 2007). We will use G'DAY and MATE to determine the sensitivity of the modelled CO2 response to key model parameters on contrasting timescales. One conclusion is that models are required that simulate both increased N uptake at high CO2 as a consequence of increased root production and soil N-cycling feedbacks. References: Norby RJ, Wullschleger SD, Hanson PJ, Gunderson CA, Tschaplinski TJ, Jastrow JD (2006) CO2 enrichment of a deciduous forest: the Oak Ridge FACE experiment. Ecological Studies 187: 231-251 (Springer-Verlag, Berlin). Pepper DA, Eliasson PE, McMurtrie RE, Corbeels M, Ågren GI, Strömgren M, Linder S (2007) Simulated mechanisms of soil N feedback on the forest CO2 response. Global Change Biology 13: 1265-1281.

  4. A High-Resolution Spontaneous 3D Dynamic Facial Expression Database

    E-print Network

    Cohn, Jeffrey F.

    behavior. Because posed and un-posed (aka "spontaneous") facial expressions differ along several dimensions.g., anger, disgust, fear, happiness, sadness, and surprise) [3][5][13]. Many studies about emotion use") facial expression differ along several dimensions [32], including complexity (especially with respect

  5. Evidence for high frequency of chromosomal mosaicism in spontaneous abortions revealed by interphase FISH analysis.

    PubMed

    Vorsanova, Svetlana G; Kolotii, Alexei D; Iourov, Ivan Y; Monakhov, Viktor V; Kirillova, Elena A; Soloviev, Ilia V; Yurov, Yuri B

    2005-03-01

    Numerical chromosomal imbalances are a common feature of spontaneous abortions. However, the incidence of mosaic forms of chromosomal abnormalities has not been evaluated. We have applied interphase multicolor fluorescence in situ hybridization using original DNA probes for chromosomes 1, 9, 13, 14, 15, 16, 18, 21, 22, X, and Y to study chromosomal abnormalities in 148 specimens of spontaneous abortions. We have detected chromosomal abnormalities in 89/148 (60.1%) of specimens. Among them, aneuploidy was detected in 74 samples (83.1%). In the remaining samples, polyploidy was detected. The mosaic forms of chromosome abnormality, including autosomal and sex chromosomal aneuploidies and polyploidy (31 and 12 cases, respectively), were observed in 43/89 (48.3%) of specimens. The most frequent mosaic form of aneuploidy was related to chromosome X (19 cases). The frequency of mosaic forms of chromosomal abnormalities in samples with male chromosomal complement was 50% (16/32 chromosomally abnormal), and in samples with female chromosomal complement, it was 47.4% (27/57 chromosomally abnormal). The present study demonstrates that the postzygotic or mitotic errors leading to chromosomal mosaicism in spontaneous abortions are more frequent than previously suspected. Chromosomal mosaicism may contribute significantly to both pregnancy complications and spontaneous fetal loss. PMID:15750024

  6. High-gain 35GHz free-electron laser-amplifier experiment

    Microsoft Academic Search

    S. H. Gold; D. L. Hardesty; A. K. Kinkead; L. R. Barnett; V. L. Granatstein

    1984-01-01

    A new intense-beam free-electron laser experiment, operating as a short-pulse amplifier at 35 GHz, has demonstrated linear growth rates of 1.2 dB\\/cm, total gain of 50 dB, and coherent emission of 17 MW, corresponding to an experimental efficiency of greater than 3%.

  7. High-gain Cerenkov free-electron laser at far infrared wavelengths

    Microsoft Academic Search

    E. P. Garate; C. H. Shaughnessy; J. E. Walsh

    1987-01-01

    The small-signal gain is derived for a Cernekov free-electron laser operating in the collective beam limit. The device consists of two dielectrically lined parallel plates driven by a cold, relativistic electron beam. The dependence of the output wavelength on the resonator parameters and the electron beam energy is examined with particular attention devoted to device operation in the far infrared

  8. The Linguistic Gains and Acculturation of American High School Students on Exchange Programs in Germany

    ERIC Educational Resources Information Center

    Lovitt, Ashli

    2013-01-01

    There has been a sharp rise in study abroad participation over the last few decades (Institute for International Education, 2011), which can largely be explained by the rise of short-term study abroad programs. While there is much to be gained from participation in such programs, mid-length and year programs may offer the greatest benefits for…

  9. Wideband and flat-gain amplifier based on high concentration erbium-doped fibres in parallel double-pass configuration

    SciTech Connect

    Hamida, B A; Cheng, X S; Harun, S W; Naji, A W; Arof, H; Al-Khateeb, W; Khan, S; Ahmad, H

    2012-03-31

    A wideband and flat gain erbium-doped fibre amplifier (EDFA) is demonstrated using a hybrid gain medium of a zirconiabased erbium-doped fibre (Zr-EDF) and a high concentration erbium-doped fibre (EDF). The amplifier has two stages comprising a 2-m-long ZEDF and 9-m-long EDF optimised for C- and L-band operations, respectively, in a double-pass parallel configuration. A chirp fibre Bragg grating (CFBG) is used in both stages to ensure double propagation of the signal and thus to increase the attainable gain in both C- and L-band regions. At an input signal power of 0 dBm, a flat gain of 15 dB is achieved with a gain variation of less than 0.5 dB within a wide wavelength range from 1530 to 1605 nm. The corresponding noise figure varies from 6.2 to 10.8 dB within this wavelength region.

  10. Spontaneous formation of highly regular superlattice structure in InGaN epilayers grown by molecular beam epitaxy

    SciTech Connect

    Wu, Z. H. [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Graduate School of Engineering, Akasaki Research Center, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Kawai, Y.; Honda, Y.; Yamaguchi, M.; Amano, H. [Graduate School of Engineering, Akasaki Research Center, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Fang, Y.-Y.; Chen, C. Q. [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Kondo, H.; Hori, M. [Graduate School of Engineering, Plasma Nanotechnology Research Center, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan)

    2011-04-04

    In this letter, we have investigated the structural properties of thick InGaN layers grown on GaN by plasma-assisted molecular beam epitaxy, using two growth rates of 1.0 and 3.6 A/s. A highly regular superlattice (SL) structure is found to be spontaneously formed in the film grown at 3.6 A/s but not in the film grown at 1.0 A/s. The faster grown film also exhibits superior structural quality, which could be due to the surface roughness suppression caused by kinetic limitation, and the inhibition of the Frank-Read dislocation generation mechanism within the spontaneously formed SL structure.

  11. Properties and preparation of high quality, free-standing GaN substrates and study of spontaneous separation mechanism

    NASA Astrophysics Data System (ADS)

    Ashraf, H.; Kudrawiec, R.; Weyher, J. L.; Serafinczuk, J.; Misiewicz, J.; Hageman, P. R.

    2010-08-01

    High quality free-standing (FS) GaN layers of thickness ˜600 ?m were prepared by exploiting spontaneous separation mechanism. Study of the mechanism revealed that the separation took place inside the GaN layer and not from the sapphire substrate. The abrupt changes in growth conditions during the deposition process and thermal mismatch between GaN and sapphire are discussed as possible causes of such spontaneous separation of GaN layers. The substrates were prepared by overgrowing GaN templates using the HCl based hydride vapor phase epitaxy (HVPE). The obtained FS-GaN substrates had a dislocation density (DD) in the order of 10 6 cm -2. Low temperature photoluminescence (PL) and reflection spectroscopy showed that the FS-GaN have good optical quality. The substrates were nearly stress free as revealed by X-ray diffraction (XRD), PL, and reflection spectroscopy.

  12. Verification of the Solar Dynamics Observatory High Gain Antenna Pointing Algorithm Using Flight Data

    NASA Technical Reports Server (NTRS)

    Bourkland, Kristin L.; Liu, Kuo-Chia

    2011-01-01

    The Solar Dynamics Observatory (SDO) is a NASA spacecraft designed to study the Sun. It was launched on February 11, 2010 into a geosynchronous orbit, and uses a suite of attitude sensors and actuators to finely point the spacecraft at the Sun. SDO has three science instruments: the Atmospheric Imaging Assembly (AIA), the Helioseismic and Magnetic Imager (HMI), and the Extreme Ultraviolet Variability Experiment (EVE). SDO uses two High Gain Antennas (HGAs) to send science data to a dedicated ground station in White Sands, New Mexico. In order to meet the science data capture budget, the HGAs must be able to transmit data to the ground for a very large percentage of the time. Each HGA is a dual-axis antenna driven by stepper motors. Both antennas transmit data at all times, but only a single antenna is required in order to meet the transmission rate requirement. For portions of the year, one antenna or the other has an unobstructed view of the White Sands ground station. During other periods, however, the view from both antennas to the Earth is blocked for different portions of the day. During these times of blockage, the two HGAs take turns pointing to White Sands, with the other antenna pointing out to space. The HGAs handover White Sands transmission responsibilities to the unblocked antenna. There are two handover seasons per year, each lasting about 72 days, where the antennas hand off control every twelve hours. The non-tracking antenna slews back to the ground station by following a ground commanded trajectory and arrives approximately 5 minutes before the formerly tracking antenna slews away to point out into space. The SDO Attitude Control System (ACS) runs at 5 Hz, and the HGA Gimbal Control Electronics (GCE) run at 200 Hz. There are 40 opportunities for the gimbals to step each ACS cycle, with a hardware limitation of no more than one step every three GCE cycles. The ACS calculates the desired gimbal motion for tracking the ground station or for slewing, and sends the command to the GCE at 5 Hz. This command contains the number of gimbals steps for that ACS cycle, the direction of motion, the spacing of the steps, and the delay before taking the first step. The AIA and HMI instruments are sensitive to spacecraft jitter. Pre-flight analysis showed that jitter from the motion of the HGAs was a cause of concern. Three jitter mitigation techniques were developed to overcome the effects of jitter from different sources. The first method is the random step delay, which avoids gimbal steps hitting a cadence on a jitter-critical mode by pseudo-randomly delaying the first gimbal step in an ACS cycle. The second method of jitter mitigation is stagger stepping, which forbids the two antennas from taking steps during the same ACS cycle in order to avoid constructively adding jitter from two antennas. The third method is the inclusion of an instrument No Step Request (NSR), which allows the instruments to request a stoppage in gimbal stepping during the times when they are taking images. During the commissioning phase of the mission, a jitter test was performed onboard the spacecraft. Various sources of jitter, such as the reaction wheels, the High Gain Antenna motors, and the motion of the instrument filter wheels, were examined to determine the level of their effect on the instruments. During the HGA portion of the test, the jitter amplitudes from the single step of a gimbal were examined, as well as the amplitudes due to the execution of various gimbal rates. These jitter levels are compared with the gimbal jitter allocations for each instrument. Additionally, the jitter test provided insight into a readback delay that exists with the GCE. Pre-flight analysis suggested that gimbal steps scheduled to occur during the later portion of an ACS cycle would not be read during that cycle, resulting in a delay in the telemetered current gimbal position. Flight data from the jitter test confirmed this expectation. Analysis is presentehat shows the readback delay does not have a negative impact on gimbal control. The decision was

  13. A numerical algorithm for optimal feedback gains in high dimensional linear quadratic regulator problems

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Ito, K.

    1991-01-01

    A hybrid method for computing the feedback gains in linear quadratic regulator problem is proposed. The method, which combines use of a Chandrasekhar type system with an iteration of the Newton-Kleinman form with variable acceleration parameter Smith schemes, is formulated to efficiently compute directly the feedback gains rather than solutions of an associated Riccati equation. The hybrid method is particularly appropriate when used with large dimensional systems such as those arising in approximating infinite-dimensional (distributed parameter) control systems (e.g., those governed by delay-differential and partial differential equations). Computational advantages of the proposed algorithm over the standard eigenvector (Potter, Laub-Schur) based techniques are discussed, and numerical evidence of the efficacy of these ideas is presented.

  14. A numerical algorithm for optimal feedback gains in high dimensional LQR problems

    NASA Technical Reports Server (NTRS)

    Banks, H. T.; Ito, K.

    1986-01-01

    A hybrid method for computing the feedback gains in linear quadratic regulator problems is proposed. The method, which combines the use of a Chandrasekhar type system with an iteration of the Newton-Kleinman form with variable acceleration parameter Smith schemes, is formulated so as to efficiently compute directly the feedback gains rather than solutions of an associated Riccati equation. The hybrid method is particularly appropriate when used with large dimensional systems such as those arising in approximating infinite dimensional (distributed parameter) control systems (e.g., those governed by delay-differential and partial differential equations). Computational advantage of the proposed algorithm over the standard eigenvector (Potter, Laub-Schur) based techniques are discussed and numerical evidence of the efficacy of our ideas presented.

  15. Polymer-nanocrystal hybrid photodetectors with planar heterojunctions designed strategically to yield a high photoconductive gain

    NASA Astrophysics Data System (ADS)

    Kyu An, Tae; Eon Park, Chan; Sung Chung, Dae

    2013-05-01

    We demonstrate an approach to enhancing the photoresponsivity of a polymer photodetector (PPD). Both conventional bulk heterojunction (BHJ) and planar heterojunction (PHJ) PPDs were fabricated considering that the interface between a CdSe nanocrystal and a polymer can create photoconductive gain. A systematic study of the illumination wavelength and light power dependence of the photocurrent gain, combined with the charge carrier transport analysis, suggested that the PHJ-PPD could yield a higher hole mobility than could be achieved in a BHJ-PPD without compromising on the selective electron trapping effects. The optimized PHJ-PPD led to a photoconductive detectivity of 1.3 × 1010 cm Hz1/2/W.

  16. High Risk of Obesity and Weight Gain for HIV-Infected Uninsured Minorities

    PubMed Central

    Taylor, Barbara S.; Liang, Yuanyuan; Garduño, L. Sergio; Walter, Elizabeth A.; Gerardi, Margit; Anstead, Gregory M.; Bullock, Delia; Turner, Barbara J.

    2014-01-01

    Background Obesity and HIV disproportionately affect minorities and have significant health risks, but few studies have examined disparities in weight change in HIV-seropositive (HIV+) cohorts. Objective To determine racial and health insurance disparities in significant weight gain in a predominately Hispanic HIV+ cohort. Methods Our observational cohort study of 1,214 non-underweight HIV+ adults from 2007-2010 had significant weight gain (?3% annual BMI increase) as primary outcome. The secondary outcome was continuous BMI over time. A four-level race-ethnicity/insurance predictor reflected the interaction between race-ethnicity and insurance: insured white (non-Hispanic), uninsured white, insured minority (Hispanic or black), or uninsured minority. Logistic and mixed effects models adjusted for: baseline BMI; age; gender; household income; HIV transmission category; antiretroviral therapy type; CD4+ count; plasma HIV-1 RNA; observation months; and visit frequency. Results The cohort was 63% Hispanic and 14% black; 13.3% were insured white, 10.0% uninsured white, 40.9% insured minority, and 35.7% uninsured minority. At baseline, 37.5% were overweight, 22.1% obese. Median observation was 3.25 years. 24.0% had significant weight gain, which was more likely for uninsured minority patients than insured whites (adjusted odds ratio=2.85 , 95%CI: 1.66, 4.90). The rate of BMI increase in mixed effects models was greatest for uninsured minorities. Of 455 overweight at baseline, 29% were projected to become obese in 4 years. Conclusions and Relevance In this majority Hispanic HIV+ cohort, 60% were overweight or obese at baseline, and uninsured minority patients gained weight more rapidly. These data should prompt greater attention by HIV providers to prevention of obesity. PMID:24121754

  17. High gain wideband compact microstrip antenna with quasi-planar surface mount horn

    Microsoft Academic Search

    A. Abdel Rahman; A. K. VennaZ; A. S Omarl

    2003-01-01

    We report a new compact square microstrip antenna with a surface mounted quasi-planar horn. The horn is made of plastic sheet and painted with silver epoxy. The horn improves the gain of the patch by 3-4.5 dB without adversely affecting bandwidth which is 2.3-9%.. Also the horn improves the isolation between array elements by 10 dB. The total thickness of

  18. High-Current-Gain SiC BJTs With Regrown Extrinsic Base and Etched JTE

    Microsoft Academic Search

    Hyung-Seok Lee; Martin Domeij; Reza Ghandi; Carl-Mikael Zetterling; Mikael Ostling

    2008-01-01

    This paper describes successful fabrication of 4H-SiC bipolar junction transistors (BJTs) with a regrown extrinsic base layer and an etched junction termination extension (JTE). Large-area 4H-SiC BJTs measuring 1.8 times 1.8 mm (with an active area of 3.24 ) showed a common emitter current gain of 42, specific on-resistance of 9 , and open-base breakdown voltage of 1.75 kV at

  19. High Gain, Fast Scan, Broad Spectrum, Parallel Beam Wavelength Dispersive X-ray Spectrometer for SEM

    SciTech Connect

    David OHara; Dr. Eric Lochmer

    2003-09-12

    Parallax Research, Inc. proposes to produce a new type of x-ray spectrometer for use with Scanning Electron Microscopy (SEM) that would have the energy resolution of WDS and the ease of use of EDS with sufficient gain for lower energies that it can be used at low beam currents as is EDS. Parallax proposes to do this by development of new multiple reflection x-ray collimation optics, new diffractor technology, new detector technology and new scan algorithms.

  20. A low power, high dynamic-range, broadband variable gain amplifier for an ultra wideband receiver

    E-print Network

    Chen, Lin

    2007-09-17

    of cross-couple transconductors multiplier ........................ 15 Fig 2.8 Differential pair with source degeneration ................................................. 16 Fig 2.9 Complementary differential pair with source degeneration... differential pairs with source degeneration as its input transconductor to convert the input voltage into current, then a programmable current mirror as its current gain stage to further amplify the current, and fixed load resistors to provide the linear...

  1. Gain-scheduled controller for the suppression of convection at high Rayleigh number.

    PubMed

    Or, A C; Speyer, J L

    2005-04-01

    Recent studies in the feedback control of Rayleigh-Bénard convection indicate that one can sustain the no-motion state at a moderate supercritical Rayleigh number (Ra) using only proportional compensation. However, stabilization occurs at a much higher Rayleigh number using linear-quadratic-Gaussian (LQG) control synthesis. The restriction is that the convection model is linear. In this paper, we show that a comparable degree of stabilization is achievable for a fully nonlinear convection state. The process is demonstrated in two stages using a fully nonlinear, 3D Boussinseq model, compensated by a reduced-order LOQ controller and a gain-schedule table. In the first stage a fully-developed convective state is suppressed through the control action at a moderate supercritical Ra. After the residual convection decays to a sufficiently small amplitude, in the second stage, we increase the Ra by a large step and switch the compensator gains using the gain-schedule table. During this change the control action is in place. Our nonlinear simulation results suggest that the nonlinear system can be stabilized to the limit predicted by the linear analysis. The simulation shows that the large Ra jump induces a large transient temperature in the conductive component, which appears to have very small impact on the stabilization. PMID:15903781

  2. Spontaneous emission spectrum of a two-level atom in a very high Q cavity

    E-print Network

    Alexia Auffèves; Benjamin Besga; Jean-Michel Gérard; Jean-Philippe Poizat

    2008-05-20

    In this paper we consider an initially excited two-level system coupled to a monomode cavity, and compute exact expressions for the spectra spontaneously emitted by each system in the general case where they have arbitrary linewidths and frequencies. Our method is based on the fact that this problem has an easily solvable classical counterpart, which provides a clear interpretation of the evidenced phenomena. We show that if the cavity linewidth is much lower than the atomic linewidth, photons are emitted at the cavity frequency, even if the atom and the cavity are strongly detuned. We also study the links between the spontaneous emission spectra and the fluorescence spectra emitted when the atom is driven by a classical field of tunable frequency.

  3. Spontaneous formation of liquid crystalline phases and phase transitions in highly concentrated plasmid DNA

    Microsoft Academic Search

    Piotr Hanczyc; Katarzyna Matczyszyn; Krzysztof Pawlik; Joanna Olesiak; Herve Leh; Malcolm Buckle

    2011-01-01

    The liquid crystalline (LC) properties of two supercoiled plasmid DNA samples, pBSK (2958 bp) and pGEM (3000 bp), have been studied using polarised light microscopy (PLM), circular dichroism (CD) and UV–Vis spectroscopy. The influence of methods of isolation on plasmid LC behaviour is described, and using PLM we have demonstrated the spontaneous formation of cholesteric fingerprint-like textures. Preliminary studies of

  4. Investigation into the influence of a high fat diet on antipsychotic-induced weight gain in female rats.

    PubMed

    Fell, M J; Neill, J C; Anjum, N; Peltola, L M; Marshall, K M

    2008-03-01

    Atypical antipsychotic drug therapy may result in substantial weight gain, increased adiposity and the promotion of metabolic abnormalities. The mechanism(s) which underlie such effects remain unclear. Previous studies in our laboratory have demonstrated significant weight gain in female rats maintained on a standard laboratory diet after sub-chronic administration of olanzapine and risperidone, but not ziprasidone. The aim of this paper is to investigate the effect of antipsychotic drugs on body weight, ingestive behaviour and adiposity in female rats with access to a high fat diet. Adult female rats given free access to a high fat diet received either olanzapine (2 mg/kg), risperidone (0.5 mg/kg), ziprasidone (2.5 mg/kg) or vehicle for 28 days. Body weight, food and water intake in addition to intra-abdominal fat deposition were assessed. Olanzapine initially increased body weight but by the end of the study olanzapine animals appeared to have lost weight compared to the vehicle-treated group. Olanzapine-induced reductions in body weight were accompanied by a significant hypophagia during weeks 3 and 4. Risperidone increased body weight during week 1 only and reduced intake of a high fat diet during weeks 3 and 4. Ziprasidone was without effect on indices of body weight and ingestive behaviour. There were no effects of antipsychotic drugs on intra-abdominal fat deposition. Access to a diet high in fat attenuated weight gain induced by olanzapine and risperidone in female rats. PMID:18308803

  5. Master-Oscillator-Power-Amplifier (MOPA) Laser Sources Used as Drive Lasers for Photoinjectors for High-Gain, Free Electron Lasers (FELs)

    E-print Network

    Anlage, Steven

    Master-Oscillator-Power-Amplifier (MOPA) Laser Sources Used as Drive Lasers for Photoinjectors for High-Gain, Free Electron Lasers (FELs) By David Leonard Demske Scholarly paper submitted In partial Milchberg #12;- 1 - Abstract The realization of extremely high gain, and high power in Free Electron Lasers

  6. A multifunctional switched-capacitor programmable gain amplifier for high-definition video analog front-ends

    NASA Astrophysics Data System (ADS)

    Hong, Zhang; Jie, Zhang; Mudan, Zhang; Xue, Li; Jun, Cheng

    2015-03-01

    A multifunctional programmable gain amplifier (PGA) that provides gain and offset adjusting abilities for high-definition video analog front-ends (AFE) is presented. With a switched-capacitor structure, the PGA also acts as a sample and holder of the analog-to-digital converter (ADC) in the AFE to reduce the power consumption and chip area of the whole AFE. Furthermore, the PGA converts the single-ended video signal into differential signal for the following ADC to reject common-mode noise and interferences. The 9-bit digital-to-analog converter (DAC) for gain and offset adjusting is embedded into the switched capacitor networks of the PGA. A video AFE integrated circuit based on the proposed PGA is fabricated in a 0.18-?m process. Simulation and measurement results show that the PGA achieves a gain control range of 0.90 to 2.34 and an offset control range of ?220 to 220 mV while consuming 10.1 mA from a 1.8 V power supply. Project supported by the National Natural Science Foundation of China (No. 61106027), and the Science and Technology Project of Shanxi Province (No. 2014K05-14).

  7. Interplay of the Chirps and Chirped Pulse Compression in a High-gain Seeded Free-electron Laser

    SciTech Connect

    Wu, Juhao; /SLAC; Murphy, J.B.; /LBNL, ALS; Emma, P.J.; /SLAC; Wang, X.J.; Watanabe, T.; /LBNL, ALS; Zhong, Xinming; /Beijing Normal U.

    2007-01-03

    In a seeded high-gain Free-electron Laser (FEL), where a coherent laser pulse interacts with an ultra-relativistic electron beam, the seed laser pulse can be frequency chirped, and the electron beam can be energy chirped. Besides these two chirps, the FEL interaction introduces an intrinsic frequency chirp in the FEL even if the above mentioned two chirps are absent. In this paper we examine the interplay of these three chirps. The problem is formulated as an initial value problem, and solved via a Green function approach. Besides the chirp evolution, we also give analytical expressions for the pulse duration and bandwidth of the FEL, which remains fully longitudinally coherent in the high gain exponential growth regime. Because the chirps are normally introduced for a final compression of the FEL pulse, some conceptual issues are discussed. We show that in order to get a short pulse duration, an energy chirp in the electron beam is necessary.

  8. High magnetic shear gain in a liquid sodium stable couette flow experiment A prelude to an alpha - omega dynamo

    SciTech Connect

    Colgate, Stirling [Los Alamos National Laboratory; Li, Jui [Los Alamos National Laboratory; Finn, John [Los Alamos National Laboratory; Pariev, Vladimir [Los Alamos National Laboratory; Beckley, Howard [NM INSTIT. OF MINING AND TECH; Si, Jiahe [NM INSTIT. OF MINING AND TECH.; Martinic, Joe [NM INSTIT. OF MINING AND TECH.; Westpfahl, David [NM INSTIT. OF TECH.; Slutz, James [NM INSTIT. OF MINING AND TECH.; Westrom, Zeb [NM INSTIT. OF TECH.; Klein, Brianna [NM INSTIT. OF MINING AND TECH.

    2010-11-08

    The {Omega}-phase of the liquid sodium {alpha}-{Omega} dynamo experiment at NMIMT in cooperation with LANL has successfully demonstrated the production of a high toroidal field, B{sub {phi}} {approx_equal} 8 x B{sub r} from the radial component of an applied poloidal magnetic field, B{sub r}. This enhanced toroidal field is produced by rotational shear in stable Couette Row within liquid sodium at Rm {approx_equal} 120. The small turbulence in stable Taylor-Couette Row is caused by Ekman Row where ({delta}v/v){sup 2} {approx} 10{sup -3}. This high {Omega}-gain in low turbulence flow contrasts with a smaller {Omega}-gain in higher turbulence, Helmholtz-unstable shear flows. This result supports the ansatz that large scale astrophysical magnetic fields are created within semi-coherent large scale motions in which turbulence plays a diffusive role that enables magnetic flux linkage.

  9. MODERATE RESISTANCE TRAINING VOLUME PRODUCES MORE FAVORABLE STRENGTH GAINS THAN HIGH OR LOW VOLUMES DURING A SHORT TERM TRAINING CYCLE

    Microsoft Academic Search

    JUAN J. GONZALEZ-BADILLO; ESTEBAN M. GOROSTIAGA; RAUL ARELLANO; MIKEL IZQUIERDO

    Gonzalez-Badillo, J.J., E.M. Gorostiaga, R. Arellano, and M. Izquierdo. Moderate resistance training volume produces more favorable strength gains than high or low volumes during a short-term training cycle. J. Strength Cond. Res. 19(3):689- 697. 2005.—The purpose of this study was to examine the effects of 3 resistance training volumes on maximal strength in the snatch (Sn), clean & jerk (C&J),

  10. Photodetectors: high-gain and low-driving-voltage photodetectors based on organolead triiodide perovskites (adv. Mater. 11/2015).

    PubMed

    Dong, Rui; Fang, Yanjun; Chae, Jungseok; Dai, Jun; Xiao, Zhengguo; Dong, Qingfeng; Yuan, Yongbo; Centrone, Andrea; Zeng, Xiao Cheng; Huang, Jinsong

    2015-03-01

    On page 1912, J. Huang, and co-workers develop a solution-processed organolead trihalide perovskite photodetector that combines a high photoconductive gain with a broad spectral response across the ultraviolet (UV) to the near-infrared (NIR). The hole traps at the top surface of the perovskites are exploited to boost the performance with an ingenious device design at extremely low driving voltage, which enables a compact integration with low-voltage circuits. PMID:25765615

  11. Sensor fault detection and isolation via high-gain observers: Application to a double-pipe heat exchanger

    Microsoft Academic Search

    R. F. Escobar; C. M. Astorga-Zaragoza; A. C. Téllez-Anguiano; D. Juárez-Romero; J. A. Hernández; G. V. Guerrero-Ramírez

    2011-01-01

    This paper deals with fault detection and isolation (FDI) in sensors applied to a concentric-pipe counter-flow heat exchanger. The proposed FDI is based on the analytical redundancy implementing nonlinear high-gain observers which are used to generate residuals when a sensor fault is presented (as software sensors). By evaluating the generated residual, it is possible to switch between the sensor and

  12. Quercetin decreases high-fat diet induced body weight gain and accumulation of hepatic and circulating lipids in mice.

    PubMed

    Hoek-van den Hil, E F; van Schothorst, E M; van der Stelt, I; Swarts, H J M; Venema, D; Sailer, M; Vervoort, J J M; Hollman, P C H; Rietjens, I M C M; Keijer, J

    2014-09-01

    Dietary flavonoids may protect against cardiovascular diseases (CVD). Increased circulating lipid levels and hepatic lipid accumulation are known risk factors for CVD. The aim of this study was to investigate the effects and underlying molecular mechanisms of the flavonoid quercetin on hepatic lipid metabolism in mice with high-fat diet induced body weight gain and hepatic lipid accumulation. Adult male mice received a 40 energy% high-fat diet without or with supplementation of 0.33 % (w/w) quercetin for 12 weeks. Body weight gain was 29 % lower in quercetin fed mice (p < 0.01), while the energy intake was not significantly different. Quercetin supplementation lowered hepatic lipid accumulation to 29 % of the amount present in the control mice (p < 0.01). (1)H nuclear magnetic resonance serum lipid profiling revealed that the supplementation significantly lowered serum lipid levels. Global gene expression profiling of liver showed that cytochrome P450 2b (Cyp2b) genes, key target genes of the transcription factor constitutive androstane receptor (Car; official symbol Nr1i3), were downregulated. Quercetin decreased high-fat diet induced body weight gain, hepatic lipid accumulation and serum lipid levels. This was accompanied by regulation of cytochrome P450 2b genes in liver, which are possibly under transcriptional control of CAR. The quercetin effects are likely dependent on the fat content of the diet. PMID:25047408

  13. Transgenic Rescue of Adipocyte Glucose-dependent Insulinotropic Polypeptide Receptor Expression Restores High Fat Diet-induced Body Weight Gain*

    PubMed Central

    Ugleholdt, Randi; Pedersen, Jens; Bassi, Maria Rosaria; Füchtbauer, Ernst-Martin; Jørgensen, Signe Marie; Kissow, Hanne-Louise; Nytofte, Nikolaj; Poulsen, Steen Seier; Rosenkilde, Mette Marie; Seino, Yutaka; Thams, Peter; Holst, Peter Johannes; Holst, Jens Juul

    2011-01-01

    The glucose-dependent insulinotropic polypeptide receptor (GIPr) has been implicated in high fat diet-induced obesity and is proposed as an anti-obesity target despite an uncertainty regarding the mechanism of action. To independently investigate the contribution of the insulinotropic effects and the direct effects on adipose tissue, we generated transgenic mice with targeted expression of the human GIPr to white adipose tissue or beta-cells, respectively. These mice were then cross-bred with the GIPr knock-out strain. The central findings of the study are that mice with GIPr expression targeted to adipose tissue have a similar high fat diet -induced body weight gain as control mice, significantly greater than the weight gain in mice with a general ablation of the receptor. Surprisingly, this difference was due to an increase in total lean body mass rather than a gain in total fat mass that was similar between the groups. In contrast, glucose-dependent insulinotropic polypeptide-mediated insulin secretion does not seem to be important for regulation of body weight after high fat feeding. The study supports a role of the adipocyte GIPr in nutrient-dependent regulation of body weight and lean mass, but it does not support a direct and independent role for the adipocyte or beta-cell GIPr in promoting adipogenesis. PMID:22027838

  14. On the Fielding of a High Gain, Shock-Ignited Target on the National Ignitiion Facility in the Near Term

    SciTech Connect

    Perkins, L J; Betti, R; Schurtz, G P; Craxton, R S; Dunne, A M; LaFortune, K N; Schmitt, A J; McKenty, P W; Bailey, D S; Lambert, M A; Ribeyre, X; Theobald, W R; Strozzi, D J; Harding, D R; Casner, A; Atzemi, S; Erbert, G V; Andersen, K S; Murakami, M; Comley, A J; Cook, R C; Stephens, R B

    2010-04-12

    Shock ignition, a new concept for igniting thermonuclear fuel, offers the possibility for a near-term ({approx}3-4 years) test of high gain inertial confinement fusion on the National Ignition Facility at less than 1MJ drive energy and without the need for new laser hardware. In shock ignition, compressed fusion fuel is separately ignited by a strong spherically converging shock and, because capsule implosion velocities are significantly lower than those required for conventional hotpot ignition, fusion energy gains of {approx}60 may be achievable on NIF at laser drive energies around {approx}0.5MJ. Because of the simple all-DT target design, its in-flight robustness, the potential need for only 1D SSD beam smoothing, minimal early time LPI preheat, and use of present (indirect drive) laser hardware, this target may be easier to field on NIF than a conventional (polar) direct drive hotspot ignition target. Like fast ignition, shock ignition has the potential for high fusion yields at low drive energy, but requires only a single laser with less demanding timing and spatial focusing requirements. Of course, conventional symmetry and stability constraints still apply. In this paper we present initial target performance simulations, delineate the critical issues and describe the immediate-term R&D program that must be performed in order to test the potential of a high gain shock ignition target on NIF in the near term.

  15. High-gain amplification in Yb:CaF2 crystals pumped by a high-brightness Yb-doped 976 nm fiber laser

    NASA Astrophysics Data System (ADS)

    Machinet, G.; Andriukaitis, G.; Sévillano, P.; Lhermite, J.; Descamps, D.; Pugžlys, A.; Baltuška, A.; Cormier, E.

    2013-05-01

    We report on high single-pass gain in Yb:CaF2 crystal longitudinally pumped with a 40 W high-brightness fiber laser source based on an ytterbium-doped ultra-large core photonic crystal rod-type fiber operating at 976 nm. A single-pass small-signal gain of 3.2 has been achieved in a 6 % Yb-doped 10-mm-long CaF2 crystal at room temperature, outperforming any CW-diode-pumped scheme and paving the way towards very promising innovative lasers and amplifiers schemes merging the Yb-doped solid-state and fiber technologies.

  16. Driving high-gain shock-ignited inertial confinement fusion targets by green laser light

    SciTech Connect

    Atzeni, Stefano; Marocchino, Alberto; Schiavi, Angelo [Dipartimento SBAI, Universita di Roma 'La Sapienza' and CNISM, Via A. Scarpa 14-16, I-00161 Roma (Italy)

    2012-09-15

    Standard direct-drive inertial confinement fusion requires UV light irradiation in order to achieve ignition at total laser energy of the order of 1 MJ. The shock-ignition approach opens up the possibility of igniting fusion targets using green light by reducing the implosion velocity and laser-driven ablation pressure. An analytical model is derived, allowing to rescale UV-driven targets to green light. Gain in the range 100-200 is obtained for total laser energy in the range 1.5-3 MJ. With respect to the original UV design, the rescaled targets are less sensitive to irradiation asymmetries and hydrodynamic instabilities, while operating in the same laser-plasma interaction regime.

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

    SciTech Connect

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

    2010-07-15

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

  18. Eigenmode analysis of a high-gain free-electron laser based on a transverse gradient undulator

    NASA Astrophysics Data System (ADS)

    Baxevanis, Panagiotis; Huang, Zhirong; Ruth, Ronald; Schroeder, Carl B.

    2015-01-01

    The use of a transverse gradient undulator (TGU) is viewed as an attractive option for free-electron lasers (FELs) driven by beams with a large energy spread. By suitably dispersing the electron beam and tilting the undulator poles, the energy spread effect can be substantially mitigated. However, adding the dispersion typically leads to electron beams with large aspect ratios. As a result, the presence of higher-order modes in the FEL radiation can become significant. To investigate this effect, we study the eigenmode properties of a TGU-based, high-gain FEL, using both an analytically-solvable model and a variational technique. Our analysis, which includes the fundamental and the higher-order FEL eigenmodes, can provide an estimate of the mode content for the output radiation. This formalism also enables us to study the trade-off between FEL gain and transverse coherence. Numerical results are presented for a representative soft X-ray, TGU FEL example.

  19. Sustained mild hypergravity reduces spontaneous cardiac baroreflex sensitivity.

    PubMed

    Yanagida, Ryo; Ogawa, Yojiro; Ueda, Kaname; Aoki, Ken; Iwasaki, Ken-ichi

    2014-10-01

    Head-to-foot gravitational force >1G (+Gz hypergravity) augments venous pooling in the lower body and reduces central blood volume during exposure, compared with 1Gz. Central hypovolemia has been reported to reduce spontaneous cardiac baroreflex sensitivity. However, no investigations have examined spontaneous cardiac baroreflex sensitivity during exposure to sustained mild +Gz hypergravity. We therefore hypothesized that mild +Gz hypergravity would reduce spontaneous cardiac baroreflex sensitivity, compared with 1Gz. To test this hypothesis, we examined spontaneous cardiac baroreflex sensitivity in 16 healthy men during exposure to mild +Gz hypergravity using a short-arm centrifuge. Beat-to-beat arterial blood pressure (tonometry) and R-R interval (electrocardiography) were obtained during 1Gz and 1.5Gz exposures. Spontaneous cardiac baroreflex sensitivity was assessed by sequence slope and transfer function gain. Stroke volume was calculated from the arterial pressure waveform using a three-element model. All indices of spontaneous cardiac baroreflex sensitivity decreased significantly (up slope: 18.6±2.3?12.7±1.6ms/mmHg, P<0.001; down slope: 19.0±2.5?13.2±1.3ms/mmHg, P=0.002; transfer function gain in low frequency: 14.4±2.2?10.1±1.1ms/mmHg, P=0.004; transfer function gain in high frequency: 22.2±7.5?12.4±3.5ms/mmHg, P<0.001). Stroke volume decreased significantly (88±5?80±6ml, P=0.025). Moreover, although systolic arterial pressure variability increased, R-R interval variability did not increase. These results suggest that even mild +Gz hypergravity reduces spontaneous cardiac baroreflex sensitivity, increasing the risk of cardiovascular disturbance during the exposure. PMID:25156804

  20. General and persistent effects of high-intensity sweeteners on body weight gain and caloric compensation in rats

    PubMed Central

    Swithers, Susan E.; Baker, Chelsea R.; Davidson, T.L.

    2009-01-01

    In four experiments, we assessed the generality of previous findings (Swithers & Davidson, 2008) that increased caloric intake, body weight gain, and reduced caloric compensation are exhibited by rats that consume a diet containing a nonnutritive, high intensity sweetener. In this earlier work, rats consumed a diet in which saccharin was mixed in low-fat yogurt, and animals were provided with a fixed amount of the yogurt. The present experiments showed that the effects of saccharin on energy intake and body weight gain are also obtained when rats were given Acesulfame Potassium (AceK), a nonnutritive high intensity sweetener that is chemically distinct from saccharin. Increased energy intake and body weight gain and impaired caloric compensation were also obtained with a saccharin-sweetened base diet (refried beans) that was calorically similar, but nutritionally distinct from low-fat yogurt. The present studies also extended earlier findings by showing that body weight differences persist after saccharin-sweetened diets are discontinued and following a shift to a diet sweetened with glucose. In addition, rats first exposed to a diet sweetened with glucose still gain additional weight when subsequently exposed to a saccharin sweetened diet. The effect of saccharin on caloric compensation was more complex in that it appeared to depend on the type of diet (yogurt or beans) in which saccharin was consumed prior to testing. The results of these experiments add support to the hypothesis that exposure to weak or non-predictive relationships between sweet tastes and caloric consequences may lead to positive energy balance. PMID:19634935

  1. Current gain collapse in microwave multifinger heterojunction bipolar transistors operated at very high power densities

    Microsoft Academic Search

    William Liu; Steve Nelson; Darrell G. Hill; Ali Khatibzadeh

    1993-01-01

    The rapid development of heterojunction bipolar transistor (HBT) technologies has led to the demonstration of high power single-chip microwave amplifiers. Because HBTs are operated at high power densities, the ultimate limits on the performance of HBTs are imposed by thermal considerations. The authors address a thermal phenomenon observed when a multifinger power HBT is operating at high power densities. This

  2. MuSET: A multiparameter and high precision sensor for downhole spontaneous electrical potential measurements

    NASA Astrophysics Data System (ADS)

    Pezard, Philippe A.; Gautier, Stéphanie; Le Borgne, Tanguy; Legros, Bruno; Deltombe, Jean-Luc

    2009-10-01

    On the basis of an existing multiparameter borehole fluid sensor ( p, T, Cw, pH, Eh), a new downhole tool designed for 200 bars and 75 °C was developed to measure the spontaneous electrical potential in situ with great precision (better than a ?V). To this end, the new sensor is based on the use of unpolarizable Pb/PbCl 2 electrodes either at the surface or downhole. In situ testing has demonstrated a capacity to identify several subsurface sources of natural electrical potential such as diffusion ones (membrane potential in the presence of clays, Fickian processes due to pore fluid salinity gradients), or else the electrokinetic mechanisms with gradients in pore fluid pressure. As a consequence, Multi-Sensors Electrical Tool (MuSET) might be used as an "electrical flowmeter" sensitive to both horizontal and vertical fluid flow in a vertical borehole.

  3. Characterization of system calibration parameters for high gain dual polarization satellite beacon diagnostics of ionospheric variations

    NASA Astrophysics Data System (ADS)

    Anderson, James P.; Phelps, Eric B.; Erickson, Philip J.; Lind, Frank D.; Coster, Anthea J.; Langston, Glen I.

    2011-10-01

    We present complementary methods for calibrating the dual-polarization feed of a ground-based tracking antenna used for ionospheric measurements. Several calibration parameters are defined which describe the state of the measurement equipment. These key parameters then form a transformational Mueller matrix which may be used to remove system bias in data received from known beacons. Several strategies are developed to quantify these time-dependent distortions for the Green Bank 140' diameter antenna and receiver, although these methods could be applied to other similar systems. One approach quantifies the receiver biases in terms of amplitude and gain differentials. This is accomplished by measuring polarimetric differences between channels using a test signal with a known amplitude and phase. Due to variations over time periods on the scale of a beacon track, this procedure is most effective when the calibration signal is injected concurrently with the beacon measurements. To determine antenna feed distortion, including cross-polarization and ellipticity, data is recorded from an external celestial source. An example shows the effectiveness of this calibration technique by comparing calibrated data to data without correction. Error estimates of the calibration parameters in the example establish an upper bound of 0.22 TEC units for measurements at 150 MHz along track.

  4. Very High Energy Gain at the Neptune Inverse Free Electron Laser Experiment

    SciTech Connect

    Musumeci, P.; Boucher, S.; Doyuran, A.; England, R. J.; Pellegrini, C.; Rosenzweig, J. B.; Travish, G.; Yoder, R. [Neptune Laboratory Department of Physics and Astronomy, University of California, Los Angeles, CA, 90095 (United States); Tochitsky, S.Ya.; Joshi, C.; Ralph, J.; Sung, C. [Department of Electrical Engineering. University of California, Los Angeles, CA, 90095 (United States); Tolmachev, S.; Varfolomeev, A.; Varfolomeev, A. Jr.; Yarovoi, T. [RRCKI, Moscow (Russian Federation)

    2004-12-07

    We report the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in an undulator strongly tapered in period and field amplitude. The IFEL driver is a CO2 10.6 {mu}m laser with power larger than 400 GW. The Rayleigh range of the laser, {approx} 1.8 cm, is much shorter than the undulator length so that the interaction is diffraction dominated. A few per cent of the injected particles are trapped in a stable accelerating bucket. Electrons with energies up to 35 MeV are measured by a magnetic spectrometer. Three-dimensional simulations, in good agreement with the measured electron energy spectrum, indicate that most of the acceleration occurs in the first 25 cm of the undulator, corresponding to an energy gradient larger than 70 MeV/m. The measured energy spectrum also indicates that higher harmonic Inverse Free Electron Laser interaction takes place in the second section of the undulator.

  5. A high-fat diet rich in corn oil reduces spontaneous locomotor activity and induces insulin resistance in mice.

    PubMed

    Wong, Chi Kin; Botta, Amy; Pither, Jason; Dai, Chuanbin; Gibson, William T; Ghosh, Sanjoy

    2015-04-01

    Over the last few decades, polyunsaturated fatty acid (PUFA), especially n-6 PUFA, and monounsaturated fatty acid content in 'Western diets' has increased manyfold. Such a dietary shift also parallels rising sedentary behavior and diabetes in the Western world. We queried if a shift in dietary fats could be linked to physical inactivity and insulin insensitivity in mice. Eight-week old female C57/Bl6 mice were fed either high-fat (HF) diets [40% energy corn oil (CO) or isocaloric olive oil (OO) diets] or chow (n=10/group) for 6 weeks, followed by estimation of spontaneous locomotor activity, body composition and in vivo metabolic outcomes. Although lean mass and resting energy expenditure stayed similar in both OO- and CO-fed mice, only CO-fed mice demonstrated reduced spontaneous locomotor activity. Such depressed activity in CO-fed mice was accompanied by a lower respiratory ratio, hyperinsulinemia and impaired glucose disposal following intraperitoneal glucose tolerance and insulin tolerance tests compared to OO-fed mice. Unlike the liver, where both HF diets increased expression of fat oxidation genes like PPARs, the skeletal muscle of CO-fed mice failed to up-regulate such genes, thereby supporting the metabolic insufficiencies observed in these mice. In summary, this study demonstrates a specific contribution of n-6 PUFA-rich oils like CO to the loss of spontaneous physical activity and insulin sensitivity in mice. If these data hold true for humans, this study could provide a novel link between recent increases in dietary n-6 PUFA to sedentary behavior and the development of insulin resistance in the Western world. PMID:25555452

  6. Shuttle orbiter Ku-band radar/communications system design evaluation: High gain antenna/widebeam horn

    NASA Technical Reports Server (NTRS)

    Iwasaki, R.; Dodds, J. G.; Broad, P.

    1979-01-01

    The physical characteristics of the high gain antenna reflector and feed elements are described. Deficiencies in the sum feed are discussed, and lack of atmospheric venting is posed as a potential problem area. The measured RF performance of the high gain antenna is examined and the high sidelobe levels measured are related to the physical characteristics of the antenna. An examination of the attributes of the feed which might be influenced by temperature extremes shows that the antenna should be insensitive to temperature variations. Because the feed support bipod structure is considered a significant contributor to the high sidelobe levels measured in the azimuth plane, pod relocation, material changes, and shaping are suggested as improvements. Alternate feed designs are presented to further improve system performance. The widebeam horn and potential temperature effects due to the polarizer are discussed as well as in the effects of linear polarization on TDRS acquisition, and the effects of circular polarization on radar sidelobe avoidance. The radar detection probability is analyzed as a function of scan overlap and target range.

  7. Transverse and temporal characteristics of a high-gain free-electron laser in the saturation regime

    NASA Astrophysics Data System (ADS)

    Huang, Zhirong; Kim, Kwang-Je

    2002-05-01

    The transverse and the temporal characteristics of a high-gain free-electron laser are governed by refractive guiding and sideband instability, respectively. Using the self-consistent Vlasov-Maxwell equations, we explicitly determine the effective index of refraction and the guided radiation mode for an electron beam with arbitrary transverse size. Electrons trapped by the guided radiation execute synchrotron oscillation and hence are susceptible to the sideband instability. We explain the spectral evolution and determine the sideband growth rate. These theoretical predictions agree well with GINGER simulation results.

  8. Statistical properties of radiation power levels from a high-gain free-electron laser at and beyond saturation

    SciTech Connect

    Schroeder, Carl B.; Fawley, William M.; Esarey, Eric

    2002-09-24

    We investigate the statistical properties (e.g., shot-to-shot power fluctuations) of the radiation from a high-gain free-electron laser (FEL) operating in the nonlinear regime. We consider the case of an FEL amplifier reaching saturation whose shot-to-shot fluctuations in input radiation power follow a gamma distribution. We analyze the corresponding output power fluctuations at and beyond first saturation, including beam energy spread effects, and find that there are well-characterized values of undulator length for which the fluctuation level reaches a minimum.

  9. High gain, low noise, fully complementary logic inverter based on bi-layer WSe{sub 2} field effect transistors

    SciTech Connect

    Das, Saptarshi; Roelofs, Andreas [Center for Nanoscale Material, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Dubey, Madan [U.S. Army Research Laboratory, Adelphi, Maryland 20783 (United States)

    2014-08-25

    In this article, first, we show that by contact work function engineering, electrostatic doping and proper scaling of both the oxide thickness and the flake thickness, high performance p- and n-type WSe{sub 2} field effect transistors (FETs) can be realized. We report record high drive current of 98??A/?m for the electron conduction and 110 ?A/?m for the hole conduction in Schottky barrier WSe{sub 2} FETs. Then, we combine high performance WSe{sub 2} PFET with WSe{sub 2} NFET in double gated transistor geometry to demonstrate a fully complementary logic inverter. We also show that by adjusting the threshold voltages for the NFET and the PFET, the gain and the noise margin of the inverter can be significantly enhanced. The maximum gain of our chemical doping free WSe{sub 2} inverter was found to be ?25 and the noise margin was close to its ideal value of ?2.5?V for a supply voltage of V{sub DD}?=?5.0?V.

  10. High gain, low noise, fully complementary logic inverter based on bi-layer WSe2 field effect transistors

    NASA Astrophysics Data System (ADS)

    Das, Saptarshi; Dubey, Madan; Roelofs, Andreas

    2014-08-01

    In this article, first, we show that by contact work function engineering, electrostatic doping and proper scaling of both the oxide thickness and the flake thickness, high performance p- and n-type WSe2 field effect transistors (FETs) can be realized. We report record high drive current of 98 ?A/?m for the electron conduction and 110 ?A/?m for the hole conduction in Schottky barrier WSe2 FETs. Then, we combine high performance WSe2 PFET with WSe2 NFET in double gated transistor geometry to demonstrate a fully complementary logic inverter. We also show that by adjusting the threshold voltages for the NFET and the PFET, the gain and the noise margin of the inverter can be significantly enhanced. The maximum gain of our chemical doping free WSe2 inverter was found to be ˜25 and the noise margin was close to its ideal value of ˜2.5 V for a supply voltage of VDD = 5.0 V.

  11. Weight Gain Induced by High-Fat Feeding Involves Increased Liver Oxidative Stress

    Microsoft Academic Search

    Fermín I. Milagro; Javier Campión; J. Alfredo Martínez

    2006-01-01

    Objective: To assess the effects of high-fat feeding on white adipose tissue gene expression and liver oxidative stress.Research Methods and Procedures: Male Wistar rats were fed on standard pelleted or high-fat diet to produce a diet-induced obesity model. Therefore, body composition, serum biochemical values and liver malondialdehyde (MDA) were determined after 56 days of feeding. Expression (mRNA) values of three

  12. High-power 1664.7-nm fiber source based on Raman and parametric gain

    Microsoft Academic Search

    D. A. Chestnut; C. J. S. de Matos; J. R. Taylor

    2002-01-01

    Summary form only given. We present a CW, single-pass, coherent fiber source at 1664.7 nm based on four-wave mixing (FWM) and first and second-order stimulated Raman scattering (SRS) from two high-power pumps. The source had a 1.7-nm 3-dB linewidth and up to 371 mW of power. The two high-power pumps consisted of a CW 1454.5-nm fiber Raman laser (FRL) and

  13. A critical examination of the evidence relating high fructose corn syrup and weight gain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of high fructose corn syrup (HFCS) has increased over the past several decades in the United States while overweight and obesity rates have risen dramatically. Some scientists hypothesize that HFCS consumption has uniquely contributed to the increasing mean body mass index (BMI) of the U.S....

  14. A Critical Examination of the Evidence Relating High Fructose Corn Syrup and Weight Gain

    Microsoft Academic Search

    Richard A. Forshee; Maureen L. Storey; David B. Allison; Walter H. Glinsmann; Gayle L. Hein; David R. Lineback; Sanford A. Miller; Theresa A. Nicklas; Gary A. Weaver; John S. White

    2007-01-01

    The use of high fructose corn syrup (HFCS) has increased over the past several decades in the United States while overweight and obesity rates have risen dramatically. Some scientists hypothesize that HFCS consumption has uniquely contributed to the increasing mean body mass index (BMI) of the U.S. population. The Center for Food, Nutrition, and Agriculture Policy convened an expert panel

  15. TARGET: Teachers As Researchers Gaining Excellence Together. Tech Prep Potential at Goshen High School.

    ERIC Educational Resources Information Center

    Hemminger, Marci; Lenfestey, Karen; Miller, Joy; Shipley, Nancy

    Three tech prep teachers and one counselor at a Vermont high school examined tech prep's effectiveness in influencing students' career decisions and their intentions to receive postsecondary education. Three methods were used to collect data at the end of the third 9-week quarter of the school year: analyzing students' course selections, grades,…

  16. A Coherent Compton Backscattering High Gain FEL using an X-Band Microwave Undulator

    Microsoft Academic Search

    S. Tantawi; V. Dolgashev; C. Nantista; C. Pellegrini; J. Rosenzweig; G. Travish

    2005-01-01

    High power microwave sources at X-Band, delivering 400 to 500 of megawatts for about 400 ns, have been recently developed. These sources can power a microwave undulator with short period and large gap, and can be used in short wavelength FELs reaching the nm region at a beam energy of about 1 GeV. We present here an experiment designed to

  17. 75 FR 61228 - Board Meeting: Technical Lessons Gained From High-Level Nuclear Waste Disposal Efforts

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-04

    ...5051 of Public Law 100-203, Nuclear Waste Policy Amendments Act of 1987, the U.S. Nuclear Waste Technical Review Board will meet in Dulles...of spent nuclear fuel and high-level radioactive waste. The Board will consider technical...

  18. Characteristics of trap-filled gallium arsenide photoconductive switches used in high gain pulsed power applications

    SciTech Connect

    ISLAM,N.E.; SCHAMILOGLU,E.; MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; JOSHI,R.P.

    2000-05-30

    The electrical properties of semi-insulating (SI) Gallium Arsenide (GaAs) have been investigated for some time, particularly for its application as a substrate in microelectronics. Of late this material has found a variety of applications other than as an isolation region between devices, or the substrate of an active device. High resistivity SI GaAs is increasingly being used in charged particle detectors and photoconductive semiconductor switches (PCSS). PCSS made from these materials operating in both the linear and non-linear modes have applications such as firing sets, as drivers for lasers, and in high impedance, low current Q-switches or Pockels cells. In the non-linear mode, it has also been used in a system to generate Ultra-Wideband (UWB) High Power Microwaves (HPM). The choice of GaAs over silicon offers the advantage that its material properties allow for fast, repetitive switching action. Furthermore photoconductive switches have advantages over conventional switches such as improved jitter, better impedance matching, compact size, and in some cases, lower laser energy requirement for switching action. The rise time of the PCSS is an important parameter that affects the maximum energy transferred to the load and it depends, in addition to other parameters, on the bias or the average field across the switch. High field operation has been an important goal in PCSS research. Due to surface flashover or premature material breakdown at higher voltages, most PCSS, especially those used in high power operation, need to operate well below the inherent breakdown voltage of the material. The lifetime or the total number of switching operations before breakdown, is another important switch parameter that needs to be considered for operation at high bias conditions. A lifetime of {approximately} 10{sup 4} shots has been reported for PCSS's used in UWB-HPM generation [5], while it has exceeded 10{sup 8} shots for electro-optic drivers. Much effort is currently being channeled in the study related to improvements of these two parameters high bias operation and lifetime improvement for switches used in pulsed power applications. The contact material and profiles are another important area of study. Although these problems are being pursued through the incorporation of different contact materials and introducing doping near contacts, it is important that the switch properties and the conduction mechanism in these switches be well understood such that the basic nature of the problems can be properly addressed. In this paper the authors report on these two basic issues related to the device operation, i.e., mechanisms for increasing the hold-off characteristics through neutron irradiation, and the analysis of transport processes at varying field conditions in trap dominated SI GaAs in order to identify the breakdown mechanism during device operation. It is expected that this study would result in a better understanding of photoconductive switches, specifically those used in high power operation.

  19. Origin of high photoconductive gain in fully transparent heterojunction nanocrystalline oxide image sensors and interconnects.

    PubMed

    Jeon, Sanghun; Song, Ihun; Lee, Sungsik; Ryu, Byungki; Ahn, Seung-Eon; Lee, Eunha; Kim, Young; Nathan, Arokia; Robertson, John; Chung, U-In

    2014-11-01

    A technique for invisible image capture using a photosensor array based on transparent conducting oxide semiconductor thin-film transistors and transparent interconnection technologies is presented. A transparent conducting layer is employed for the sensor electrodes as well as interconnection in the array, providing about 80% transmittance at visible-light wavelengths. The phototransistor is a Hf-In-Zn-O/In-Zn-O heterostructure yielding a high quantum-efficiency in the visible range. PMID:25219518

  20. Inflection point caustic problems and solutions for high-gain dual-shaped reflectors

    Microsoft Academic Search

    Victor Galindo-Israel; Thavath Veruttipong; S. Rengarajan; W. Imbriale

    1990-01-01

    The singular nature of the UTD (uniform geometrical theory of diffraction) subreflector scattered field at the vicinity of the main reflector edge (for a high-grain antenna design) is investigated. It is shown that the singularity in the UTD edge-diffracted and slope-diffracted fields is due to the reflection distance parameter approaching infinity in the transition functions. While the GO (geometrical optics)

  1. Role of spontaneous current oscillations during high-efficiency electrotransformation of thermophilic anaerobes.

    PubMed

    Tyurin, Michael V; Sullivan, Charles R; Lynd, Lee R

    2005-12-01

    Current oscillations at about 24 MHz were observed during electrotransformation (ET) of the thermophilic anaerobes Clostridium thermocellum ATCC 27405, C. thermocellum DSM 1313, and Thermoanaerobacterium saccharolyticum YS 485, using a pulse gated by a square signal generated by a custom generator. In experiments in which only the field strength was varied, all three of these strains resulted in a one-to-one correspondence between the appearance of current oscillations and successful ET. Oscillations accompanied ET of both C. thermocellum strains only at field strengths of > or =12 kV/cm, and ET was only observed above the same threshold. Similarly, for T. saccharolyticum, oscillations were only observed at field strengths of > or =10 kV/cm, and ET was only observed above the same threshold. When a passive electrical filter consisting of an inductor and resistor in parallel was added to the system to prevent the development of oscillations, ET efficiencies were reduced dramatically for all three strains at all field strengths tested. The maximum tested field strength, 25 kV/cm, resulted in the maximum measured transformation efficiency for all three strains. At this field strength, the efficiency of ET in the absence of oscillations was decreased compared to that observed in the presence of oscillations by 500-fold for C. thermocellum ATCC 27405, 2,500-fold for C. thermocellum DSM 1313, and 280-fold for T. saccharolyticum. Controls using the same apparatus with Escherichia coli cells or a resistor with a value representative of the direct current resistance of typical cell samples did not develop oscillations, and ET efficiencies obtained with E. coli were the same with or without the electrical filter included in the pulse generator circuit. The results are interpreted to indicate that spontaneously arising oscillations have a large beneficial effect on transformation efficiency in the system employed here and that the development of oscillations in this system is affected by the cell species present. PMID:16332787

  2. Caffeine prevents weight gain and cognitive impairment caused by a high-fat diet while elevating hippocampal BDNF

    PubMed Central

    Moy, Gregory A.; McNay, Ewan C.

    2013-01-01

    Obesity, high-fat diets, and subsequent type 2 diabetes (T2DM) are associated with cognitive impairment. Moreover, T2DM increases the risk of Alzheimer’s disease (AD) and leads to abnormal elevation of brain beta-amyloid levels, one of the hallmarks of AD. The psychoactive alkaloid caffeine has been shown to have therapeutic potential in AD but the central impact of caffeine has not been well-studied in the context of a high-fat diet. Here we investigated the impact of caffeine administration on metabolism and cognitive performance, both in control rats and in rats placed on a high-fat diet. The effects of caffeine were significant: caffeine both (i) prevented the weight-gain associated with the high-fat diet and (ii) prevented cognitive impairment. Caffeine did not alter hippocampal metabolism or insulin signaling, likely because the high-fat-fed animals did not develop full-blown diabetes; however, caffeine did prevent or reverse a decrease in hippocampal brain-derived neurotrophic factor (BDNF) seen in high-fat-fed animals. These data confirm that caffeine may serve as a neuroprotective agent against cognitive impairment caused by obesity and/or a high-fat diet. Increased hippocampal BDNF following caffeine administration could explain, at least in part, the effects of caffeine on cognition and metabolism. PMID:23220362

  3. High matrix metalloproteinase-9 expression induces angiogenesis and basement membrane degradation in stroke-prone spontaneously hypertensive rats after cerebral infarction

    PubMed Central

    Hou, Huilian; Zhang, Guanjun; Wang, Hongyan; Gong, Huilin; Wang, Chunbao; Zhang, Xuebin

    2014-01-01

    Basement membrane degradation and blood-brain barrier damage appear after cerebral infarction, severely impacting neuronal and brain functioning; however, the underlying pathogenetic mechanisms remain poorly understood. In this study, we induced cerebral infarction in stroke-prone spontaneously hypertensive rats by intragastric administration of high-sodium water (1.3% NaCl) for 7 consecutive weeks. Immunohistochemical and immunofluorescence assays demonstrated that, compared with the non-infarcted contralateral hemisphere, stroke-prone spontaneously hypertensive rats on normal sodium intake and Wistar-Kyoto rats, matrix metalloproteinase-9 expression, the number of blood vessels with discontinuous collagen IV expression and microvessel density were significantly higher, and the number of continuous collagen IV-positive blood vessels was lower in the infarct border zones of stroke-prone spontaneously hypertensive rats given high-sodium water. Linear correlation analysis showed matrix metalloproteinase-9 expression was positively correlated with the number of discontinuously collagen IV-labeled blood vessels and microvessel density in cerebral infarcts of stroke-prone spontaneously hypertensive rats. These results suggest that matrix metalloproteinase-9 upregulation is associated with increased regional angiogenesis and degradation of collagen IV, the major component of the basal lamina, in stroke-prone spontaneously hypertensive rats with high-sodium water-induced focal cerebral infarction. PMID:25206775

  4. Imaging at soft X-ray wavelengths with high-gain microchannel plate detector systems

    NASA Technical Reports Server (NTRS)

    Timothy, J. Gethyn

    1986-01-01

    Multianode microchannel array (MAMA) detector systems with formats of 256 x 1024 pixels and active areas of 6 x 26 mm are now under evaluation at visible, UV and soft X-ray wavelengths. Very-large-format versions of the MAMA detectors with formats of 2048 x 2048 pixels and active areas of 52 x 52 mm are under development for use in the NASA Goddard Space Telescope Imaging Spectrograph (STIS). Open-structure versions of these detectors with Cs I photocathodes can provide a high-resolution imaging capability at EUV and soft X-ray wavelengths and can deliver a maximum count rate from each array in excess of 10 to the 6th counts/s. In addition, these detector systems have the unique capability to determine the arrival time of a detected photon to an accuracy of 100 ns or better. The construction, mode of operation, and performance characteristics of the MAMA detectors are described, and the program for the development of the very-large-format detectors is outlined.

  5. Theory of quantum frequency conversion and type-II parametric down-conversion in the high-gain regime

    NASA Astrophysics Data System (ADS)

    Christ, Andreas; Brecht, Benjamin; Mauerer, Wolfgang; Silberhorn, Christine

    2013-05-01

    Frequency conversion (FC) and type-II parametric down-conversion (PDC) processes serve as basic building blocks for the implementation of quantum optical experiments: type-II PDC enables the efficient creation of quantum states such as photon-number states and Einstein-Podolsky-Rosen (EPR)-states. FC gives rise to technologies enabling efficient atom-photon coupling, ultrafast pulse gates and enhanced detection schemes. However, despite their widespread deployment, their theoretical treatment remains challenging. Especially the multi-photon components in the high-gain regime as well as the explicit time-dependence of the involved Hamiltonians hamper an efficient theoretical description of these nonlinear optical processes. In this paper, we investigate these effects and put forward two models that enable a full description of FC and type-II PDC in the high-gain regime. We present a rigorous numerical model relying on the solution of coupled integro-differential equations that covers the complete dynamics of the process. As an alternative, we develop a simplified model that, at the expense of neglecting time-ordering effects, enables an analytical solution. While the simplified model approximates the correct solution with high fidelity in a broad parameter range, sufficient for many experimental situations, such as FC with low efficiency, entangled photon-pair generation and the heralding of single photons from type-II PDC, our investigations reveal that the rigorous model predicts a decreased performance for FC processes in quantum pulse gate applications and an enhanced EPR-state generation rate during type-II PDC, when EPR squeezing values above 12 dB are considered.

  6. Transverse-to-Longitudinal Emittance Exchange to Improve Performance of High-Gain Free-Electron Lasers

    SciTech Connect

    Emma, P.; Huang, Z.; /SLAC; Kim, K.-J.; /Argonne; Piot, P.; /Northern Illinois U. /Fermilab

    2006-09-21

    The ability to generate small transverse emittance is perhaps the main limiting factor for the performance of high-gain x-rays free-electron lasers (FELs). Noting that beams from an rf photocathode gun can have energy spread much smaller than required for efficient FEL interaction, we present a method to produce normalized transverse emittance at or below about 0.1 {micro}m, which will lead to a significantly shorter length undulator as well as a lower electron beam energy for an x-ray FEL project. The beam manipulation consists of producing an unequal partition of the initially equal emittances into two dissimilar emittances by a flat beam technique and exchanging the larger transverse emittance with a small longitudinal emittance. We study various issues involved in the manipulation. In particular, a new emittance exchange optics we found enables an exact emittance exchange necessary for this scheme.

  7. Highly entangled photons and rapidly responding polarization qubit phase gates in a room-temperature active Raman gain medium

    SciTech Connect

    Hang Chao [State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University, Shanghai 200062 (China); Centro de Fisica Teorica e Computacional, Universidade de Lisbon, Complex Interdisciplinary, Avenida Professor Gama Pinto 2, Lisbon P-1649-003 (Portugal); Huang Guoxiang [State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University, Shanghai 200062 (China); Institute of Nonlinear Physics, Zhejiang Normal University, Jinhua, Zhejiang 321004 (China)

    2010-11-15

    We present a scheme for obtaining entangled photons and quantum phase gates in a room-temperature four-state tripod-type atomic system with two-mode active Raman gain (ARG). We analyze the linear and nonlinear optical responses of this ARG system and show that the scheme is fundamentally different from those based on electromagnetically induced transparency and hence can avoid significant probe-field absorption as well as a temperature-related Doppler effect. We demonstrate that highly entangled photon pairs can be produced and rapidly responding polarization qubit phase gates can be constructed based on the unique features of the enhanced cross-phase-modulation and superluminal probe-field propagation of the system.

  8. Air-stable n-type organic thin-film transistor array and high gain complementary inverter on flexible substrate

    NASA Astrophysics Data System (ADS)

    Fujisaki, Yoshihide; Nakajima, Yoshiki; Kumaki, Daisuke; Yamamoto, Toshihiro; Tokito, Shizuo; Kono, Takahiro; Nishida, Jun-ichi; Yamashita, Yoshiro

    2010-09-01

    Air-stable n-type organic thin-film transistor (TFT) arrays and a complementary inverter circuit were fabricated on a flexible substrate. A benzobis(thiadiazole) (BBT) derivative-based TFT showed excellent air- stability and performances such as an electron mobility of over 0.1 cm2/V s, a large ON/OFF ratio over 108 when combined with a cross-linkable olefin-type polymer gate dielectric. In addition, an organic complementary inverter that combined the BBT derivative and a pentacene TFT demonstrated a sharp switching behavior and a high gain of over 150. We attribute these excellent characteristics to a combination of the low-lying lowest unoccupied molecular orbital level of n-type semiconductor material and the low interface trap of the gate dielectric.

  9. Gimbals Drive and Control Electronics Design, Development and Testing of the LRO High Gain Antenna and Solar Array Systems

    NASA Technical Reports Server (NTRS)

    Chernyakov, Boris; Thakore, Kamal

    2010-01-01

    Launched June 18, 2009 on an Atlas V rocket, NASA's Lunar Reconnaissance Orbiter (LRO) is the first step in NASA's Vision for Space Exploration program and for a human return to the Moon. The spacecraft (SC) carries a wide variety of scientific instruments and provides an extraordinary opportunity to study the lunar landscape at resolutions and over time scales never achieved before. The spacecraft systems are designed to enable achievement of LRO's mission requirements. To that end, LRO's mechanical system employed two two-axis gimbal assemblies used to drive the deployment and articulation of the Solar Array System (SAS) and the High Gain Antenna System (HGAS). This paper describes the design, development, integration, and testing of Gimbal Control Electronics (GCE) and Actuators for both the HGAS and SAS systems, as well as flight testing during the on-orbit commissioning phase and lessons learned.

  10. VUV RADIATION SOURCES: High-power short-pulse xenon dimer spontaneous radiation source

    NASA Astrophysics Data System (ADS)

    Lomaev, Mikhail I.; Mesyats, Gennadii A.; Rybka, D. V.; Tarasenko, Viktor F.; Baksht, E. Kh

    2007-06-01

    A high-power VUV radiation source based on a self-sustained nanosecond volume discharge in an inhomogeneous electric field is developed. It is shown that the volume discharge can be formed at high xenon and helium pressures without using a preionisation source. The 8-ns (FWHM), 172-nm, 1-MW radiation pulses emitted into a total solid angle are obtained in xenon at a pressure of 12 atm.

  11. Measurement and Simulation of Spontaneous Raman Scattering Spectra in High-Pressure, Fuel-Rich H2-Air Flames

    NASA Technical Reports Server (NTRS)

    Kojima, Jun; Nguyen, Quang-Viet

    2003-01-01

    Rotational vibrational spontaneous Raman spectra (SRS) of H2, N2, and H2O have been measured in H2-air flames at pressures up to 30 atm as a first stem towards establishing a comprehensive Raman spectral database for temperatures and species in high-pressure combustion. A newly developed high-pressure burner facility provides steady, reproducible flames with a high degree of flow precision. We have obtained an initial set of measurements that indicate the spectra are of sufficient quality in terms of spectral resolution, wavelength coverage, and signal-to-noise ratio for use in future reference standards. The fully resolved Stokes and anti-Stokes shifted SRS spectra were collected in the visible wavelength range (400-700 nm) using pulse-stretched 532 nm excitation and a non-intensified CCD spectrograph with a high-speed shutter. Reasonable temperatures were determined via the intensity distribution of rotational H2 lines at stoichiometry and fuel-rich conditions. Theoretical Raman spectra of H2 were computed using a semi-classical harmonic-oscillator model with recent pressure broadening data and were compared with experimental results. The data and simulation indicated that high-J rotational lines of H2 might interfere with the N2 vibrational Q-branch lines, and this could lead to errors in N2-Raman thermometry based on the line-fitting method. From a comparison of N2 Q-branch spectra in lean H2 low-pressure (1.2 atm) and high-pressure (30 atm) flames, we found no significant line-narrowing or -broadening effects at the current spectrometer resolution of 0.04 nm.

  12. Do High-Functioning People with Autism Spectrum Disorder Spontaneously Use Event Knowledge to Selectively Attend to and Remember Context-Relevant Aspects in Scenes?

    ERIC Educational Resources Information Center

    Loth, Eva; Gomez, Juan Carlos; Happe, Francesca

    2011-01-01

    This study combined an event schema approach with top-down processing perspectives to investigate whether high-functioning children and adults with autism spectrum disorder (ASD) spontaneously attend to and remember context-relevant aspects of scenes. Participants read one story of story-pairs (e.g., burglary or tea party). They then inspected a…

  13. Effects of a high-fat diet on spontaneous metastasis of Lewis lung carcinoma in plasminogen activator inhibitor-1 deficient and wild-type mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated the effects of plasminogen activator inhibitor-1 (PAI-1) deficiency on spontaneous metastasis of Lewis lung carcinoma (LLC) in PAI-1 deficient (PAI-1-/-) and wildtype mice (C57BL/6J background) fed the AIN93G diet or that diet modified with 45% calories from fat. The high-fat diet i...

  14. Low loss high gain 300 V-200 A class normally-off SIT module for DC motor control

    Microsoft Academic Search

    Shinobu AOKI; Naoshi TSUKIYAMA; Toshimitsu IRIE; Hiroshi TADANO; Jun-ichi NISHIZAWA

    1988-01-01

    A 300 V, 200 A normally-off-type SIT (static induction transistor) module has been fabricated. The module consists of two 100 A planar-gate SIT chips which show a current gain of 325 and voltage gain of 0.23 V at ID=100 A. The design, fabrication and electrical characteristics are discussed. Improved trade off between the current gain and breakdown voltage has been

  15. Design considerations and implementation of a programmable high-frequency continuous-time filter and variable-gain amplifier in submicrometer CMOS

    Microsoft Academic Search

    Venu Gopinathan; Maurice Tarsia; Davy Choi

    1999-01-01

    We report on an approach to designing high-speed, low-voltage programmable continuous-time filters with an embedded variable-gain amplifier (VGA). The methods we describe here are aimed at implementation in ultra-short-channel, low-voltage CMOS technologies. The seventh-order equiripple filter and VGA combination described here has a -3-dB frequency programmable from 30 to 100 MHz, gain programmable from 0 to 17 dB and 12

  16. Design and testing of a large-aperture, high-gain, Brewster{close_quote}s angle zigzag Nd:glass slab amplifier

    Microsoft Academic Search

    M. J. Shoup; J. H. Kelly; D. L. Smith

    1997-01-01

    At the University of Rochester we have constructed and tested a large-aperture, (1.0Ã6.5 cm), high-gain (8) Brewster{close_quote}s angle zigzag Nd:glass amplifier with a repetition rate of 2 Hz. This amplifier has a gain uniformity of ±3% and a maximum stress-induced depolarization >2.5%. {copyright} 1997 Optical Society of America

  17. Consumption of Clarified Grapefruit Juice Ameliorates High-Fat Diet Induced Insulin Resistance and Weight Gain in Mice

    PubMed Central

    Chudnovskiy, Rostislav; Thompson, Airlia; Tharp, Kevin; Hellerstein, Marc; Napoli, Joseph L.; Stahl, Andreas

    2014-01-01

    To determine the metabolic effects of grapefruit juice consumption we established a model in which C57Bl/6 mice drank 25–50% sweetened GFJ, clarified of larger insoluble particles by centrifugation (cGFJ), ad libitum as their sole source of liquid or isocaloric and sweetened water. cGFJ and control groups consumed similar amounts of liquids and calories. Mice fed a high-fat diet and cGFJ experienced a 18.4% decrease in weight, a 13–17% decrease in fasting blood glucose, a three-fold decrease in fasting serum insulin, and a 38% decrease in liver triacylglycerol values, compared to controls. Mice fed a low-fat diet that drank cGFJ experienced a two-fold decrease in fasting insulin, but not the other outcomes observed with the high-fat diet. cGFJ consumption decreased blood glucose to a similar extent as the commonly used anti-diabetic drug metformin. Introduction of cGFJ after onset of diet-induced obesity also reduced weight and blood glucose. A bioactive compound in cGFJ, naringin, reduced blood glucose and improved insulin tolerance, but did not ameliorate weight gain. These data from a well-controlled animal study indicate that GFJ contains more than one health-promoting neutraceutical, and warrant further studies of GFJ effects in the context of obesity and/or the western diet. PMID:25296035

  18. Consumption of clarified grapefruit juice ameliorates high-fat diet induced insulin resistance and weight gain in mice.

    PubMed

    Chudnovskiy, Rostislav; Thompson, Airlia; Tharp, Kevin; Hellerstein, Marc; Napoli, Joseph L; Stahl, Andreas

    2014-01-01

    To determine the metabolic effects of grapefruit juice consumption we established a model in which C57Bl/6 mice drank 25-50% sweetened GFJ, clarified of larger insoluble particles by centrifugation (cGFJ), ad libitum as their sole source of liquid or isocaloric and sweetened water. cGFJ and control groups consumed similar amounts of liquids and calories. Mice fed a high-fat diet and cGFJ experienced a 18.4% decrease in weight, a 13-17% decrease in fasting blood glucose, a three-fold decrease in fasting serum insulin, and a 38% decrease in liver triacylglycerol values, compared to controls. Mice fed a low-fat diet that drank cGFJ experienced a two-fold decrease in fasting insulin, but not the other outcomes observed with the high-fat diet. cGFJ consumption decreased blood glucose to a similar extent as the commonly used anti-diabetic drug metformin. Introduction of cGFJ after onset of diet-induced obesity also reduced weight and blood glucose. A bioactive compound in cGFJ, naringin, reduced blood glucose and improved insulin tolerance, but did not ameliorate weight gain. These data from a well-controlled animal study indicate that GFJ contains more than one health-promoting neutraceutical, and warrant further studies of GFJ effects in the context of obesity and/or the western diet. PMID:25296035

  19. A low-carbohydrate/high-fat diet reduces blood pressure in spontaneously hypertensive rats without deleterious changes in insulin resistance

    PubMed Central

    Bosse, John D.; Lin, Han Yi; Sloan, Crystal; Zhang, Quan-Jiang; Abel, E. Dale; Pereira, Troy J.; Dolinsky, Vernon W.; Symons, J. David

    2013-01-01

    Previous studies reported that diets high in simple carbohydrates could increase blood pressure in rodents. We hypothesized that the converse, a low-carbohydrate/high-fat diet, might reduce blood pressure. Six-week-old spontaneously hypertensive rats (SHR; n = 54) and Wistar-Kyoto rats (WKY; n = 53, normotensive control) were fed either a control diet (C; 10% fat, 70% carbohydrate, 20% protein) or a low-carbohydrate/high-fat diet (HF; 20% carbohydrate, 60% fat, 20% protein). After 10 wk, SHR-HF had lower (P < 0.05) mean arterial pressure than SHR-C (148 ± 3 vs. 159 ± 3 mmHg) but a similar degree of cardiac hypertrophy (33.4 ± 0.4 vs. 33.1 ± 0.4 heart weight/tibia length, mg/mm). Mesenteric arteries and the entire aorta were used to assess vascular function and endothelial nitric oxide synthase (eNOS) signaling, respectively. Endothelium-dependent (acetylcholine) relaxation of mesenteric arteries was improved (P < 0.05) in SHR-HF vs. SHR-C, whereas contraction (potassium chloride, phenylephrine) was reduced (P < 0.05). Phosphorylation of eNOSSer1177 increased (P < 0.05) in arteries from SHR-HF vs. SHR-C. Plasma glucose, insulin, and homoeostatic model of insulin assessment were lower (P < 0.05) in SHR-HF vs. SHR-C, whereas peripheral insulin sensitivity (insulin tolerance test) was similar. After a 10-h fast, insulin stimulation (2 U/kg ip) increased (P < 0.05) phosphorylation of AktSer473 and S6 in heart and gastrocnemius similarly in SHR-C vs. SHR-HF. In conclusion, a low-carbohydrate/high-fat diet reduced blood pressure and improved arterial function in SHR without producing signs of insulin resistance or altering insulin-mediated signaling in the heart, skeletal muscle, or vasculature. PMID:23604708

  20. Asymmetric Two-Beam Coupling with High Optical Gain and High Beam Diffraction in External-Electric-Field-Free Polymer Composites

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Naoto; Shimizu, Yusuke

    2004-06-01

    This paper presents high-performance asymmetric two-beam coupling, beam diffraction and holographic recording in polymeric composites without poling and applying an external electric field. The polymer composites are based on poly(2-(9-carbazoyl)ethyl methacrylate) (PCzEMA) and poly(N-vinyl carbazole) (PVCz) as host matrices with 2,4,7-trinitro-9-fluorenone (TNF) as a sensitizer, four kinds of plasticizer; tricresyl phosphate (TCP), n-butyl benzyl phthalate (BBP), diphenyl phthalate (DPP), and dicyclohexyl phthalate (DCP); and (s)-(-)-1-(4-nitrophenyl)-2-pyrrolidine-methanol (NPP) as a nonlinear optical dye. The gain coefficient and diffraction efficiency increased markedly with increasing TNF and NPP concentrations. The highest net gain coefficient of 101.9 cm-1 with optical gain of 224 cm-1 and absorption coefficient of 122.1 cm-1 was obtained for PVCz/NPP/DDP/TNF (35/20/40/5), and the highest diffraction efficiency of 88% was achieved for PCzEMA/NPP/TCP/TNF (35/30/30/5) and PVCz/NPP/DDP/TNF (35/20/39/6) composites. The BBP plasticizer significantly enhanced the speed of two-beam coupling and diffraction grating formation for both PVCz and PCzEMA composites. Holographic images stored in the polymer composites were clearly read out using a probe beam. The key point for achieving the external-electric-field-free high performance of asymmetric energy transfer and diffraction efficiency is to have a high concentration of TNF (5 or 7 wt%).

  1. Cooling by spontaneous decay of highly excited antihydrogen atoms in magnetic traps.

    PubMed

    Pohl, T; Sadeghpour, H R; Nagata, Y; Yamazaki, Y

    2006-11-24

    An efficient cooling mechanism of magnetically trapped, highly excited antihydrogen (H) atoms is presented. This cooling, in addition to the expected evaporative cooling, results in trapping of a large number of H atoms in the ground state. It is found that the final fraction of trapped atoms is insensitive to the initial distribution of H magnetic quantum numbers. Expressions are derived for the cooling efficiency, demonstrating that magnetic quadrupole (cusp) traps provide stronger cooling than higher order magnetic multipoles. The final temperature of H confined in a cusp trap is shown to depend as approximately 2.2T(n0)n(0)(-2/3) on the initial Rydberg level n0 and temperature T(n0). PMID:17155740

  2. SPONTANEOUS CATALYTIC WET AIR OXIDATION DURING PRE-TREATMENT OF HIGH-LEVEL RADIOACTIVE WASTE SLUDGE

    SciTech Connect

    Koopman, D.; Herman, C.; Pareizs, J.; Bannochie, C.; Best, D.; Bibler, N.; Fellinger, T.

    2009-10-01

    Savannah River Remediation, LLC (SRR) operates the Defense Waste Processing Facility for the U.S. Department of Energy at the Savannah River Site. This facility immobilizes high-level radioactive waste through vitrification following chemical pretreatment. Catalytic destruction of formate and oxalate ions to carbon dioxide has been observed during qualification testing of non-radioactive analog systems. Carbon dioxide production greatly exceeded hydrogen production, indicating the occurrence of a process other than the catalytic decomposition of formic acid. Statistical modeling was used to relate the new reaction chemistry to partial catalytic wet air oxidation of both formate and oxalate ions driven by the low concentrations of palladium, rhodium, and/or ruthenium in the waste. Variations in process conditions led to increases or decreases in the total oxidative destruction, as well as partially shifting the preferred species undergoing destruction from oxalate ion to formate ion.

  3. Quantitative Analysis of Spectral Interference of Spontaneous Raman Scattering in High-Pressure Fuel-Rich H2-Air Combustion

    NASA Technical Reports Server (NTRS)

    Kojima, Jun; Nguyen, Quang-Viet

    2004-01-01

    We present a theoretical study of the spectral interferences in the spontaneous Raman scattering spectra of major combustion products in 30-atm fuel-rich hydrogen-air flames. An effective methodology is introduced to choose an appropriate line-shape model for simulating Raman spectra in high-pressure combustion environments. The Voigt profile with the additive approximation assumption was found to provide a reasonable model of the spectral line shape for the present analysis. The rotational/vibrational Raman spectra of H2, N2, and H2O were calculated using an anharmonic-oscillator model using the latest collisional broadening coefficients. The calculated spectra were validated with data obtained in a 10-atm fuel-rich H2-air flame and showed excellent agreement. Our quantitative spectral analysis for equivalence ratios ranging from 1.5 to 5.0 revealed substantial amounts of spectral cross-talk between the rotational H2 lines and the N2 O-/Q-branch; and between the vibrational H2O(0,3) line and the vibrational H2O spectrum. We also address the temperature dependence of the spectral cross-talk and extend our analysis to include a cross-talk compensation technique that removes the nterference arising from the H2 Raman spectra onto the N2, or H2O spectra.

  4. Fast Ionic Diffusion-Enabled Nanoflake Electrode by Spontaneous Electrochemical Pre-Intercalation for High-Performance Supercapacitor

    PubMed Central

    Mai, Liqiang; Li, Han; Zhao, Yunlong; Xu, Lin; Xu, Xu; Luo, Yanzhu; Zhang, Zhengfei; Ke, Wang; Niu, Chaojiang; Zhang, Qingjie

    2013-01-01

    Layered intercalation compounds NaxMnO2 (x = 0.7 and 0.91) nanoflakes have been prepared directly through wet electrochemical process with Na+ ions intercalated into MnO2 interlayers spontaneously. The as-prepared NaxMnO2 nanoflake based supercapacitors exhibit faster ionic diffusion with enhanced redox peaks, tenfold-higher energy densities up to 110?Wh·kg?1 and higher capacitances over 1000?F·g?1 in aqueous sodium system compared with traditional MnO2 supercapacitors. Due to the free-standing electrode structure and suitable crystal structure, NaxMnO2 nanoflake electrodes also maintain outstanding electrochemical stability with capacitance retention up to 99.9% after 1000 cycles. Besides, pre-intercalation effect is further studied to explain this enhanced electrochemical performance. This study indicates that the suitable pre-intercalation is effective to improve the diffusion of electrolyte cations and other electrochemical performance for layered oxides, and suggests that the as-obtained nanoflakes are promising materials to achieve the hybridization of both high energy and power density for advanced supercapacitors.

  5. Prismatic louver active façades for natural illumination and thermal energy gain in high-rise and commercial buildings

    NASA Astrophysics Data System (ADS)

    Vlachokostas, A.; Volkmann, C.; Madamopoulos, N.

    2013-06-01

    High-rise and commercial buildings in urban centers present a great challenge in terms of their energy consumption. Due to maximization of rentable square footage, the preferred urban façade system over the past 50 years has been the "curtain wall", only a few inches thick and comprised of modular steel or aluminum framing and predominant glass infills. The perceived Achilles heel of these modern glass façade systems is their thermal inefficiency: They are inadequate thermal barriers and exhibit excessive solar gain. The excessive solar gain has a negative impact on lighting and cooling loads of the entire building. This negative impact will be further exacerbated with rising energy costs. However, rather than view the glass façade's uncontrolled solar gain merely as a weakness contributing to higher energy consumption, the condition could indeed be considered as related to an energy solution. These glass façades can be retrofitted to operate as a provider of daylight and energy for the rest of the building, taking advantage of the overexposure to the sun. With today's technology, the sun's abundant renewable energy can be the driving force for the energy transition of these building envelopes. Illumination, thermal energy, and electricity production can be directly supplied from the sun, and when correctly and efficiently managed, they can lead to a significantly less energy-intensive building stock. We propose a multi-purpose, prismatic, louver-based façade to perform both daylight and thermal energy harvesting with a goal of offering a better daylight environment for the occupants, and reduce the energy consumption and carbon footprint of the building. While decentralized air-conditioning units are commonly accepted as façade "plug-ins", such decentralization could be utilized with more benefits by passively managing the interior space conditions, without using any extra power. Just as living organisms respond and adapt to the environmental changes in their surroundings, the proposed multi-purpose prismatic louver façade can be responsive and resilient to daytime sky conditions, environmental temperatures and occupant needs by exploiting options presented by the three sides of the prismatic louvers. The façade is highly configurable since every side of the prismatic louver façade can perform a different operation. The prism itself operates as a redirector of sunlight from the glass façade to the ceiling and consequently diffuses the sunlight throughout the room, providing higher and more uniform illumination levels. In addition, each side of the prismatic louver can be implemented in multiple ways (e.g., visibly transparent photovoltaic cells, luminescent solar concentrators). The ability to rotate the prismatic louvers along their axes allows the user to expose a set of different surfaces to the sun's radiation in accordance with different climatic conditions and occupant needs. Thus, the prismatic louvers help achieve a selective control and management of the incoming light that allows us to manipulate the incoming energy for the benefit of the building and its occupants.

  6. Sensor fault detection and isolation via high-gain observers: application to a double-pipe heat exchanger.

    PubMed

    Escobar, R F; Astorga-Zaragoza, C M; Téllez-Anguiano, A C; Juárez-Romero, D; Hernández, J A; Guerrero-Ramírez, G V

    2011-07-01

    This paper deals with fault detection and isolation (FDI) in sensors applied to a concentric-pipe counter-flow heat exchanger. The proposed FDI is based on the analytical redundancy implementing nonlinear high-gain observers which are used to generate residuals when a sensor fault is presented (as software sensors). By evaluating the generated residual, it is possible to switch between the sensor and the observer when a failure is detected. Experiments in a heat exchanger pilot validate the effectiveness of the approach. The FDI technique is easy to implement allowing the industries to have an excellent alternative tool to keep their heat transfer process under supervision. The main contribution of this work is based on a dynamic model with heat transfer coefficients which depend on temperature and flow used to estimate the output temperatures of a heat exchanger. This model provides a satisfactory approximation of the states of the heat exchanger in order to allow its implementation in a FDI system used to perform supervision tasks. PMID:21501838

  7. A study of the Rayleigh-Taylor instability in direct drive for LMJ high gain fusion targets

    NASA Astrophysics Data System (ADS)

    Meyer, Christophe; Canaud, Benoit; Fortin, Xavier; Garaude, Florence

    2002-11-01

    A comparative study of the Rayleigh-Taylor instability at the ablation front during the acceleration stage was undertaken. The hydrodynamic behavior of two different types of high gain fusion capsules was investigated. The growth rate and surface roughness were inferred through the use of 1D simulations carried out with the hydrodynamics code FCI2, coupled to the Goncharov-Betti, Takabe and Haan models. The growth rates obtained by the Goncharov-Betti model are in good agreement with 2D simulation results. It is also shown that the ablative stabilisation term used in the Takabe relation is strongly material dependent with a value of 1.5 for CH and 2.5 for cryogenic DT. It appears clearly from this study that the 'all DT' target produces lower growth rates (1.9 ns-1) than the plastic target (3.9 ns-1). Finally, by applying the Haan saturation model, we reveal that the CH target is very likely to break-up while perturbations from the 'all DT' target are still kept below a safe level.

  8. Pulse compression using angular multiplexing in a high-gain 1.7 kJ amplifier

    Microsoft Academic Search

    G. N. Hays; J. M. Hoffman

    1981-01-01

    Pulse compression using angular multiplexing is demonstrated on a large-scale hydrogen-fluoride laser system. For a train of two 24 ns pulses, the essential elements of this scheme are evaluated as a function of interpulse separation time. Included are energy-extraction efficiency, overall temporal pulse distortion, leading-edge contrast-ratio distortion, and suppression of amplified spontaneous emission relative to a single long-duration input pulse.

  9. Spontaneously formed unilamellar vesicles.

    PubMed

    Nieh, Mu-Ping; Kucerka, Norbert; Katsaras, John

    2009-01-01

    Mixtures of long- and short-chain phospholipids can spontaneously form uniform unilamellar vesicles (ULVs) with diameters 50 nm (polydispersities of <0.3) or less. The morphology of these ULVs has mainly been characterized using small angle neutron scattering (SANS), a technique highly suited for the study of hydrogenous materials. Once formed, these ULVs have turned out to be highly stable and show great promise as imaging and therapeutic carriers. PMID:19913159

  10. The X-Target: A novel high gain target with single-sided heavy-ion beam illumination

    NASA Astrophysics Data System (ADS)

    Henestroza, Enrique

    2012-10-01

    A new inertial-fusion target configuration, the X-target, using one-sided heavy ion axial illumination has been explored [1]. It takes advantage of the unique energy deposition properties of heavy ion beams that have a classical, long penetration range. This class of target uses heavy ion beams to compress and ignite deuterium-tritium (DT) fuel that fills the interior of metal cases that have side-view cross sections in the shape of an ``X''. X-targets that incorporate inside the case a propellant (plastic) and a pusher (aluminum) surrounding the DT are capable of assembling fuel areal densities ˜2 g/cm^2 using two MJ-scale annular beams to implode quasi-spherically the target to peak DT densities ˜100 g/cm^3. A 3MJ fast-ignition solid ion beam heats the fuel to thermonuclear temperatures in ˜200 ps to start the burn propagation, obtaining gains of ˜300. The main concern for the X-target is the amount of high-Z atomic mixing at the ignition zone produced by hydro-instabilities, which, if large enough, could cool the fuel during the ignition process and prevent the propagation of the fusion burn. Analytic estimates and implosion calculations using the radiation hydrodynamics code HYDRA in 2D (RZ), at typical Eulerian mesh resolutions of a few microns, have shown that for the relatively low implosion velocities, low stagnation fuel densities, and low quasi-spherical fuel convergence ratios of the X-target, these hydro-instabilities do not have a large effect on the burning process. These preliminary studies need to be extended by further hydrodynamic calculations using finer resolution, complemented with turbulent mix modeling and validated by experiments, to ascertain the stability of the X-target design. We will present the current status of the X-target. [4pt] [1] E. Henestroza and B. G. Logan, Phys. Plasmas 19, 072706 (2012)

  11. Early Spontaneous Deficiency of Calcitonin Renal Binding Sites in Rats with a High Incidence of Calcitonin-secreting Tumors (WAG\\/Rij)1

    Microsoft Academic Search

    Z. Bouizar; W. H. Rostone; F. Treilhou-Lahille; E. Pidoux; G. Milhaud; M. S. Moukhtar

    1987-01-01

    Old rats of the WAG\\/Rij strain have a high incidence (50%) of medullary thyroid carcinoma, a calcitonin (CT>secrering tumor. We have characterized and quantified the topographical distribution of (125I)salmon calcitonin (sCT) binding sites in the kidneys of this strain, as compared to Wistar CF rats (2% incidence of spontaneous medullary thyroid carcinoma). We report here that, up to 15 days

  12. Gaining Ground

    ERIC Educational Resources Information Center

    Newman, Leslie A.; Rollison, Margaret L.

    2011-01-01

    In the 2006-07 school year, North Brunswick High School--a rural, racially and economically diverse high school in Leland, North Carolina--was identified as a priority school by the North Carolina Department of Public Instruction. Overall student proficiency was at 48.6%, indicating that less than one-half of all students earned a score of…

  13. The dynamics of amplified spontaneous emission in CdSe/ZnSe quantum dots

    E-print Network

    Kundys, D O; Wells, J P R; Tartakovskii, A I; Skolnick, M S; Dang, Le Si; Lutsenko, E V; Tarasuk, N P; Lyublinskaya, O G; Toropov, A A; Ivanov, S V

    2014-01-01

    We have used the variable stripe technique and pump-probe spectroscopy to investigate both gain and the dynamics of amplified spontaneous emission from CdSe quantum dot structures. We have found modal gain coefficients of 75 and 32 1/cm for asymmetric and symmetric waveguide structures, respectively. Amplified spontaneous emission decay times of 150 and 300 ps and carrier capture times of 15 and 40 ps were measured for the structures with high and low material gains respectively. The difference in the capture times are related to the fact that for the symmetric waveguide, carriers diffuse into the active region from the uppermost ZnMgSSe cladding layer, yielding a longer rise time for the pump-probe signals for this sample.

  14. An analysis of gain-switched semiconductor lasers generating pulse-code-modulated light with a high bit rate

    Microsoft Academic Search

    M. S. Demokan; A. Nacaroglu

    1984-01-01

    A theoretical analysis of gain-switched semiconductor lasers is described. Results of the numerical solution of the coupled rate equations for photon and electron densities are presented, along with analytical expressions which have been derived by using certain approximations to solve these nonlinear differential equations. The two sets of results are seen to be in good agreement. The design requirements to

  15. Gaining Acceptance

    ERIC Educational Resources Information Center

    Villano, Matt

    2007-01-01

    Back in the 1990s, when Bill Clinton was president and the internet was still a novelty, college recruitment was remarkably low-tech. Most prospective students visited high school guidance offices, wrote away for information about schools, attended college fairs, and visited campuses they were considering. Most admissions and recruiting activities…

  16. Blue-green small-signal gain and saturation in a luminescent polymer gain medium

    NASA Astrophysics Data System (ADS)

    Kobayashi, Takeyuki; Flämmich, Michael; Jordan, Grace; D'Arcy, Rebekah; Rüther, Manuel; Blau, Werner J.; Suzuki, Yasuhiro; Kaino, Toshikuni

    2006-09-01

    The authors study the optical gain and saturation behavior in a blue-green-emitting luminescent polymer gain medium. Based on the results of amplified spontaneous emission measurements, the gain coefficients, the gain-length product, and the corresponding small-signal gain are determined. By the use of the variable stripe length method, large net gain coefficients of up to 106±6cm-1 have been measured under nanosecond photopumping. The large gain has favorable implications for the development of short wavelength lasers and amplifiers. Their study shows that a small-signal gain of 19dB is achievable with a very compact optical amplifier with a 400?m length.

  17. High CO2 concentration increases relative leaf carbon gain under dynamic light in Dipterocarpus sublamellatus seedlings in a tropical rain forest, Malaysia.

    PubMed

    Tomimatsu, Hajime; Iio, Atsuhiro; Adachi, Minaco; Saw, Leng-Guan; Fletcher, Christine; Tang, Yanhong

    2014-09-01

    Understory plants in tropical forests often experience a low-light environment combined with high CO2 concentration. We hypothesized that the high CO2 concentration may compensate for leaf carbon loss caused by the low light, through increasing light-use efficiency of both steady-state and dynamic photosynthetic properties. To test the hypothesis, we examined CO2 gas exchange in response to an artificial lightfleck in Dipterocarpus sublamellatus Foxw. seedlings under contrasting CO2 conditions: 350 and 700??mol?CO2?mol(-1) air in a tropical rain forest, Pasoh, Malaysia. Total photosynthetic carbon gain from the lightfleck was about double when subjected to the high CO2 when compared with the low CO2 concentration. The increase of light-use efficiency in dynamic photosynthesis contributed 7% of the increased carbon gain, most of which was due to reduction of photosynthetic induction to light increase under the high CO2. The light compensation point of photosynthesis decreased by 58% and the apparent quantum yield increased by 26% at the high CO2 compared with those at the low CO2. The study suggests that high CO2 increases photosynthetic light-use efficiency under both steady-state and fluctuating light conditions, which should be considered in assessing the leaf carbon gain of understory plants in low-light environments. PMID:25187569

  18. Diffusion tensor imaging using a high-temperature superconducting resonator in a 3 T magnetic resonance imaging for a spontaneous rat brain tumor

    NASA Astrophysics Data System (ADS)

    Lin, In-Tsang; Yang, Hong-Chang; Chen, Jyh-Horng

    2013-02-01

    This study investigates the peri-tumor signal abnormalities of a spontaneous brain tumor in a rat by using a 4 cm high-temperature superconducting (HTS) surface resonator. Fractional anisotropy (FA) values derived from diffusion tensor imaging reflect the interstitial characteristic of the peri-lesional tissues of brain tumors. Low FA indicates interstitial tumor infiltration and tissue injury, while high FA indicates better tissue integrity. Better delineation of tissue contents obtained by the HTS surface resonator at 77 K may facilitate therapeutic strategy and improve clinical outcomes.

  19. Ultrabroad-band Raman amplifiers pumped and gain-equalized by wavelength-division-multiplexed high-power laser diodes

    Microsoft Academic Search

    Shu Namiki; Yoshihiro Emori

    2001-01-01

    This paper reviews recent progress in broad-band Raman amplifiers for wavelength-division-multiplexed (WDM) applications. After the fundamentals of Raman amplifiers are discussed in contrast to erbium-doped fiber amplifiers, a new technique called “WDM pumping” is introduced to obtain ultrabroad and flat gain in Raman amplifiers only using WDM diode pumps. The design issues of this technique are then developed to realize

  20. High gain-density K-band P-HEMT LNA MMIC for LMDS and satellite communication

    Microsoft Academic Search

    Yutaka Mimino; M. Hirata; K. Nakamura; K. Sakamoto; Y. Aoki; S. Kuroda

    2000-01-01

    A miniature and broadband, K-band p-HEMT LNA MMIC, that incorporates simple lumped matching elements and series bias topologies, has been developed for LMDS (Local Multi-point Distribution Service) and satellite communication. The gain and noise figure is 14.5 +\\/- 1.5 dB and 1.7 +\\/- 0.2 dB, respectively, at frequencies between 23 and 30 GHz. The die size of the MMIC is

  1. "Making it explicit" makes a difference: evidence for a dissociation of spontaneous and intentional level 1 perspective taking in high-functioning autism.

    PubMed

    Schwarzkopf, Sarah; Schilbach, Leonhard; Vogeley, Kai; Timmermans, Bert

    2014-06-01

    The ability of perspective taking is a fundamental aspect of social cognition. The ability to decide, what another person can or cannot see is referred to as "level 1 perspective taking." This is thought to be a process that we can make use of intentionally, but which also takes place spontaneously. Autism is characterized by impairments of social interaction, which are thought to be related to deficits in implicit rather than explicit perspective taking. In order to assess both levels of processing with regard to perspective taking, we employed an established task in patients and controls. Our results demonstrate that both groups engage in spontaneous level 1 perspective taking. In contrast to controls, however, patients reacted more slowly if they had to verify the other's as compared to their own perspective, which shows that participants with high-functioning autism have selective difficulties in explicit, but not implicit, level 1 perspective taking. These findings demonstrate that while spontaneous level 1 perspective taking appears to be intact in autism, this ability is impaired in patients when used explicitly. PMID:24632324

  2. High spin studies of neutron-rich nuclei produced in the spontaneous fission process of californium-252

    NASA Astrophysics Data System (ADS)

    Zhang, Xueqian

    2001-08-01

    From an experiment with GAMMMASPHERE and a 252Cf spontaneous fission source, high spin studies of several neutron-rich nuclei have been carried out. In the mass region A ~ 150, a new negative-parity band in 154Nd and new negative-parity levels in 152Nd were identified and the yrast bands were extended to 18+ in 154Nd and 20+ 152Nd in a triple gamma coincidence study. These new negative-parity bands are consistent with octupole vibrational mode rather than the stable octupole deformation seen in Ba and Ce nuclei. There is a constant difference as a function of spin between the J1 values for the negative-parity band in 152Nd and J1 for the similar negative-parity band in 154Nd, however, their J2 values are essentially identical above the 4 + state. These bands indicate a new kind of identical bands associated with an octupole vibrational mode. In mass region A ~ 110, we have observed new bands in 113,115,117,118 Pd up to moderately high spin. The newly identified negative-parity yrast band energy level systematics built on the / isomeric states fit smoothly with the known systematic for other Pd isotopes, and show a minimum excitation energy at N = 68 related to a mid-shell closure. These new negative- parity yrast bands indicate a first band crossing at ¢? ~ 0.45 MeV, nearly identical to those seen in 109,111Pd, but significantly higher than those in the positive yrast parity bands in 113,115Pd and in the even-even Pd isotopes. We have interpreted the new negative-parity yrast bands as having band crossings from the alignment of a nh/ pair, and this suggests that 113,115,117Pd maintain a prolate shape. Additionally, we have observed two new bands in 113,115 Pd, which are tentatively assigned positive parity with band crossings about 0.25 and 0.32 MeV. These lower frequencies are consistent with a nh/ pair alignment. In the neutron-rich 118Pd, the first band crossing at a frequency of ¢? ~ 0.29 MeV was observed in its yrast band. This band crossing frequency is substantially lower than the first band crossing frequency of ¢? ~ 0.45 MeV observed the yrast bands in the lighter odd mass Pd isotopes and the crossing at ¢? = 0.35 in the yrast bands in 112,114,116Pd. This lower crossing frequency is well reproduced by the quasi- neutron Routhian calculation by assuming that the neutron-pairing gap is reduced in 118Pd. The calculation show a two nh/ band crossing at ¢? ~ 0.3 in agreement with the experimental value. A reduction in neutron pairing is responsible in Cranking model for lowering the crossing frequency. This band crossing in the new yrast cascade in 118Pd as well as those in 112,114,116Pd are interpreted based on a two h/ neutron configuration. Our result indicates 118 Pd still maintains a prolate shape. It's found that the crossing frequency in 118Pd is considerably lower and weaker than for the other even Pd isotopes. In the even-even 88,90,92Kr, all yrast bands were studied and extended to 8+, 10+, 12+, respectively. Quasi-gamma bands in 90,92Kr, and possibly one in 88Kr were identified. These data provide useful information about the interplay of collective and independent particle excitations in these three nuclei. Additionally, the coexisting of vibrational motion near the ground state and rotational collective motion at intermediate spins is observed in neutron-rich 90Kr.

  3. Improving proliferation resistance of high breeding gain generation 4 reactors using blankets composed of light water reactor waste

    SciTech Connect

    Hellesen, C.; Grape, S.; Haakanson, A.; Jacobson Svaerd, S.; Jansson, P. [Division of Applied Nuclear Physics, Uppsala University, Aangstroemlaboratoriet Laegerhyddsvaegen 1, 751 20 Uppsala (Sweden)

    2013-07-01

    Fertile blankets can be used in fast reactors to enhance the breeding gain as well as the passive safety characteristics. However, such blankets typically result in the production of weapons grade plutonium. For this reason they are often excluded from Generation IV reactor designs. In this paper we demonstrate that using blankets manufactured directly from spent light water (LWR) reactor fuel it is possible to produce a plutonium product with non-proliferation characteristics on a par with spent LWR fuel of 30-50 MWd/kg burnup. The beneficial breeding and safety characteristics are retained. (authors)

  4. Single crystalline Er2O3:sapphire films as potentially high-gain amplifiers at telecommunication wavelength

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. S.; Sadofev, S.; Schäfer, P.; Kalusniak, S.; Henneberger, F.

    2014-11-01

    Single crystalline thin films of Er2O3, demonstrating efficient 1.5 ?m luminescence of Er3+ at room temperature were grown on Al2O3 substrate by molecular beam epitaxy. The absorption coefficient at 1.536 ?m was found to reach 270 cm-1 translating in a maximal possible gain of 1390 dBcm-1. In conjunction with the 10% higher refractive index as compared to Al2O3, this opens the possibility to use Er2O3:sapphire films as short-length waveguide amplifiers in telecommunication.

  5. Design of a high-gain laser diode-array pumped Nd:YAG alternating precessive slab amplifier (APS amplifier)

    NASA Technical Reports Server (NTRS)

    Coyle, D. B.

    1991-01-01

    In the design of space-qualifiable laser systems for ranging and altimetry, such as NASA's Geodynamic Laser Ranging System (GLRS), the transmitter must be kept small, powerful yet efficient, and must consist of as few components as possible. A novel preamplifier design is examined which requires no external beam steering optics, yielding a compact component with simple alignment procedures. The gains achieved are comparable to multipass zigzag amplifiers using two or more sets of external optics for extra passes through the amplifying medium.

  6. Targeting Binge Eating for the Prevention of Excessive Weight Gain: Interpersonal Psychotherapy for Adolescents at High-Risk for Adult Obesity

    PubMed Central

    Tanofsky-Kraff, Marian; Wilfley, Denise E.; Young, Jami F.; Mufson, Laura; Yanovski, Susan Z.; Glasofer, Deborah R.; Salaita, Christine G.

    2007-01-01

    The most prevalent disordered eating pattern described in overweight youth is loss of control (LOC) eating, during which individuals experience an inability to control the type or amount of food they consume. LOC eating is associated cross-sectionally with greater adiposity in children and adolescents, and appears to predispose youth to gain weight or body fat above that expected during normal growth, thus likely contributing to obesity in susceptible individuals. No prior studies have examined whether LOC eating can be decreased by interventions in children or adolescents without full-syndrome eating disorders, or whether programs reducing LOC eating prevent inappropriate weight gain attributable to LOC eating. Interpersonal psychotherapy, a form of therapy that was designed to treat depression and has been adapted for the treatment of eating disorders, has demonstrated efficacy in reducing binge eating episodes and inducing weight stabilization among adults diagnosed with binge eating disorder. In this paper, we propose a theoretical model of excessive weight gain in adolescents at high-risk for adult obesity who engage in LOC eating and associated overeating patterns. A rationale is provided for interpersonal psychotherapy as an intervention to slow the trajectory of weight gain in at-risk youth, with the aim of preventing or ameliorating obesity in adulthood. PMID:17557971

  7. Time resolved gain/loss studies under low and high power loading for the XeF C-A transition

    SciTech Connect

    Sze, R.C. (Los Alamos National Lab., NM (USA)); Sentis, M. (Institut de Mecanique des Fluides, 13 - Marseille (France)); Vannini, M. (Consiglio Nazionale delle Ricerche, Florence (Italy). Ist. di Elettronica Quantistica)

    1990-01-01

    The behavior of gain versus peak power deposition and the gain-length product versus total energy deposited are measured for devices with power deposition levels from 1 to 13 MW/cm{sup 3} under a variety of gas mixtures. The temporal correlation between the power deposition and gain shows that both the fluorescence and the gain occur after the power deposition has concluded for excitation pulses in the range of 10--30 ns. We find that both B-X and C-A fluorescence takes place in the afterglow and their temporal shapes are similar. This indicates that the C and B states are tightly coupled. This tight coupling has two detrimental consequences for C-state lasing. First is that the population of the B and C states are approximately equal rather than 90% in the C state believed to exist for short pulse electron beam excitation. We believe this close coupling is due to the presence of electric fields in the afterglow which keep the electron temperature relatively hot. The relative populations of the B and C states are determined by a Boltzman distribution governed by the electron temperature and their relative energy separation. Second is that with the C state lifetime approximately the same as the B state lifetime the C-A saturation intensity is very high and efficient energy extraction is substantially more difficult. 5 refs., 10 figs.

  8. High d(+)-fructose diet adversely affects testicular weight gain in weaning rats?protection by moderate d(+)-glucose diet.

    PubMed

    Shibata, Katsumi; Fukuwatari, Tsutomu

    2013-01-01

    The use of high D(+)-fructose corn syrup has increased over the past several decades in the developed countries, while overweight and obesity rates and the related diseases have risen dramatically. However, we found that feeding a high D(+)-fructose diet (80% D(+)-fructose as part of the diet) to weaning rats for 21 days led to reduced food intake (50% less, P < 0.0001) and thus delayed the weight gains in the body (40% less, P < 0.0001) and testes (40% less, P < 0.0001) compared to the no D(+)-fructose diet. We also challenged a minimum requirement of dietary D(+)-glucose for preventing the adverse effects of D(+)-fructose, such as lower food intake and reduction of body weight and testicular weight; the minimum requirement of D(+)-glucose was ?23% of the diet. This glucose amount may be the minimum requirement of exogenous glucose for reducing weight gain. PMID:23935370

  9. Investigation of the gain regimes and gain parameters of the free electron laser dispersion equation

    Microsoft Academic Search

    E. Jerby; A. Gover

    1985-01-01

    The small signal gain curve and various gain parameters have been computed by solving numerically the generalized gain-dispersion equation of free electron lasers (FEL), which characterizes the conventional magnetic bremsstrahlung FEL, as well as a large number of other FEL devices. The method includes high gain, collective, and axial velocity spread effects, and some waveguide effects. The FEL gain regimes

  10. Heat Resistance and Salt Hypersensitivity in Lactococcus lactis Due to Spontaneous Mutation of llmg_1816 (gdpP) Induced by High-Temperature Growth

    PubMed Central

    Smith, William M.; Pham, Thi Huong; Lei, Lin; Dou, Junchao; Soomro, Aijaz H.; Beatson, Scott A.; Dykes, Gary A.

    2012-01-01

    During construction of several gene deletion mutants in Lactococcus lactis MG1363 which involved a high-temperature (37.5°C) incubation step, additional spontaneous mutations were observed which resulted in stable heat resistance and in some cases salt-hypersensitive phenotypes. Whole-genome sequencing of one strain which was both heat resistant and salt hypersensitive, followed by PCR and sequencing of four other mutants which shared these phenotypes, revealed independent mutations in llmg_1816 in all cases. This gene encodes a membrane-bound stress signaling protein of the GdpP family, members of which exhibit cyclic dimeric AMP (c-di-AMP)-specific phosphodiesterase activity. Mutations were predicted to lead to single amino acid substitutions or protein truncations. An independent llmg_1816 mutant (?1816), created using a suicide vector, also displayed heat resistance and salt hypersensitivity phenotypes which could be restored to wild-type levels following plasmid excision. L. lactis ?1816 also displayed improved growth in response to sublethal concentrations of penicillin G. High-temperature incubation of a wild-type industrial L. lactis strain also resulted in spontaneous mutation of llmg_1816 and heat-resistant and salt-hypersensitive phenotypes, suggesting that this is not a strain-specific phenomenon and that it is independent of a plasmid integration event. Acidification of milk by the llmg_1816-altered strain was inhibited by lower salt concentrations than the parent strain. This study demonstrates that spontaneous mutations can occur during high-temperature growth of L. lactis and that inactivation of llmg_1816 leads to temperature resistance and salt hypersensitivity. PMID:22923415

  11. High-power diode side-pumped Nd:YAG laser on the low gain three lines near 1.1 ?m

    Microsoft Academic Search

    Z. Wang; Y. Bo; S. Xie; C. Li; Y. Xu; F. Yang; J. Xu; Q. Peng; J. Zhang; D. Cui; Z. Xu

    2011-01-01

    We demonstrate a high-power diode side-pumped Nd:YAG laser on the low gain three lines near 1.1 ?m. By tuning the tilting\\u000a angle of a solid etalon in the cavity, the laser can be selectively operated at 1112, 1116 and 1123 nm either in continuous-wave\\u000a (CW) mode or in actively Q-switched (QS) mode, respectively. The highest average CW output powers were 75, 47

  12. High-power continuous-wave diode-pumped Nd:YAlO3 laser that emits on low-gain 1378-and 1385-nm transitions

    E-print Network

    Paris-Sud XI, Université de

    High-power continuous-wave diode-pumped Nd:YAlO3 laser that emits on low-gain 1378- and 1385-nm transitions Sylvie Yiou, Franc¸ ois Balembois, Patrick Georges, and Alain Brun Efficient operation of a diode than for the 1.34- m line.10 Consequently, an efficient diode-pumped laser at 1378 and 1385 nm presents

  13. Spontaneous Resolution of Pneumocystis jirovecii Pneumonia on High-Resolution Computed Tomography in a Patient with Renal Cell Carcinoma

    PubMed Central

    Tanaka, Yasutaka; Saraya, Takeshi; Kurai, Daisuke; Ishii, Haruyuki; Takizawa, Hajime; Goto, Hajime

    2014-01-01

    Patient: Male, 59 Final Diagnosis: Pneumocystis jirovecii pneumonia Symptoms: Low grade fever Medication: — Clinical Procedure: Transbronchial lung biopsy Specialty: Pulmonology Objective: Rare disease Background: Spontaneous resolution of Pneumocystis jirovecii pneumonia has rarely been reported. Case Report: A 59-year-old man presented to our hospital because of pyrexia (38°C) and shaking chills for 2 days. He had a history of right nephrectomy due to renal cell carcinoma and left upper lobectomy for lung metastasis in the last 1.5 years. Two months previously, he was treated with oral prednisolone (20 mg/day) plus the intravenous mTOR inhibitor, temsirolimus (25 mg/week), for brain metastasis. On radiological examination, thoracic computed tomography showed diffuse ground glass opacities spreading in bilateral middle to lower lung fields. Although transbronchial biopsy specimens and bronchoalveolar lavage fluid demonstrated the presence of accumulation of black-colored Pneumocystis jirovecii cysts in the lung, his chief complaints and radiological abnormalities disappeared completely with no treatment. This case demonstrates a unique clinical presentation of Pneumocystis jirovecii pneumonia, in that spontaneous resolution was noted on clinical and sequential radiological evaluations. Conclusions: Increasing numbers of cytotoxic drugs and biological therapies have emerged, and changes in the immune status due to underlying diseases or administration of immunosuppressive drugs might affect the inflammatory process of Pneumocystis jirovecii pneumonia, as in the present case. PMID:25396336

  14. A gain-coefficient switched Alexandrite laser

    NASA Astrophysics Data System (ADS)

    Lee, Chris J.; van der Slot, Peter J. M.; Boller, Klaus-J.

    2013-01-01

    We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.

  15. A gain-coefficient switched Alexandrite laser

    E-print Network

    Lee, Chris J; Boller, Klaus-J

    2012-01-01

    We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.

  16. Early metabolic adaptation in C57BL/6 mice resistant to high fat diet induced weight gain involves an activation of mitochondrial oxidative pathways.

    PubMed

    Boulangé, Claire L; Claus, Sandrine P; Chou, Chieh J; Collino, Sebastiano; Montoliu, Ivan; Kochhar, Sunil; Holmes, Elaine; Rezzi, Serge; Nicholson, Jeremy K; Dumas, Marc E; Martin, François-Pierre J

    2013-04-01

    We investigated the short-term (7 days) and long-term (60 days) metabolic effect of high fat diet induced obesity (DIO) and weight gain in isogenic C57BL/6 mice and examined the specific metabolic differentiation between mice that were either strong-responders (SR), or non-responders (NR) to weight gain. Mice (n = 80) were fed a standard chow diet for 7 days prior to randomization into a high-fat (HF) (n = 56) or a low-fat (LF) (n = 24) diet group. The (1)H NMR urinary metabolic profiles of LF and HF mice were recorded 7 and 60 days after the diet switch. On the basis of the body weight gain (BWG) distribution of HF group, we identified NR mice (n = 10) and SR mice (n = 14) to DIO. Compared with LF, HF feeding increased urinary excretion of glycine conjugates of ?-oxidation intermediate (hexanoylglycine), branched chain amino acid (BCAA) catabolism intermediates (isovalerylglycine, ?-keto-?-methylvalerate and ?-ketoisovalerate) and end-products of nicotinamide adenine dinucleotide (NAD) metabolism (N1-methyl-2-pyridone-5-carboxamide, N1-methyl-4-pyridone-3-carboxamide) suggesting up-regulation of mitochondrial oxidative pathways. In the HF group, NR mice excreted relatively more hexanoylglycine, isovalerylglycine, and fewer tricarboxylic acid (TCA) cycle intermediate (succinate) in comparison to SR mice. Thus, subtle regulation of ketogenic pathways in DIO may alleviate the saturation of the TCA cycle and mitochondrial oxidative metabolism. PMID:23473242

  17. Structure of neutron-rich nuclei and neutron multiplicities in spontaneous fission

    Microsoft Academic Search

    J. H. Hamilton; G. M. Ter-Akopian; Yu. Ts. Oganessian; J. Kormicki; S. J. Zhu; M. G. Wang; L. Q; K. Butler-Moore; A. V. Ramayya; W. C. Ma; B. R. S. Babu; D. Shi; J. K. Deng; G. S. Popeko; A. V. Daniel; W. Greiner; A. Sandulescu; J. D. Cole; R. Aryaeinejad; J. Kliman; V. Polhorsky; M. Morhac; N. R. Johnson; I. Y. Lee; F. K. McGowan; L. K. Peker

    1996-01-01

    New insights into the fission process and the structure of neutron-rich nuclei have been gained by measuring ?-? and ?-?-? coincidences of the prompt ?-rays following the spontaneous fission of 252Cf. The data were taken with the Compton Suppression Spectrometer System at HHIRF. New high spin levels were observed in 143,145,147Ba Only in 143Ba are intertwined bands observed with the

  18. Management of intractable spontaneous epistaxis

    PubMed Central

    Rudmik, Luke

    2012-01-01

    Background: Epistaxis is a common otolaryngology emergency and is often controlled with first-line interventions such as cautery, hemostatic agents, or anterior nasal packing. A subset of patients will continue to bleed and require more aggressive therapy. Methods: Intractable spontaneous epistaxis was traditionally managed with posterior nasal packing and prolonged hospital admission. In an effort to reduce patient morbidity and shorten hospital stay, surgical and endovascular techniques have gained popularity. A literature review was conducted. Results: Transnasal endoscopic sphenopalatine artery ligation and arterial embolization provide excellent control rates but the decision to choose one over the other can be challenging. The role of transnasal endoscopic anterior ethmoid artery ligation is unclear but may be considered in certain cases when bleeding localizes to the ethmoid region. Conclusion: This article will focus on the management of intractable spontaneous epistaxis and discuss the role of endoscopic arterial ligation and embolization as it pertains to this challenging clinical scenario. PMID:22391084

  19. Compact high power mid-infrared optical parametric oscillator pumped by a gain-switched fiber laser with "figure-of-h" pulse shape.

    PubMed

    Jiang, Peipei; Chen, Tao; Wu, Bo; Yang, Dingzhong; Hu, Chengzhi; Wu, Pinghui; Shen, Yonghang

    2015-02-01

    We demonstrate a compact high power mid-infrared (MIR) optical parametric oscillator (OPO) pumped by a gain-switched linearly polarized, pulsed fiber laser. The gain-switched fiber laser was constructed with a piece of Yb doped polarization maintaining (PM) fiber, a pair of fiber Bragg gratings written into the matched passive PM fiber and 6 pigtailed pump laser diodes working at 915 nm with 30 W output peak power each. By modulating the pulse width of the pump laser diode, simple pedestal-free pulse shape or pedestal-free trailing pulse shape ("figure-of-h" as we call it) could be achieved from the gain-switched fiber laser. The laser was employed as the pump of a two-channel, periodically poled magnesium oxide lithium niobate-based OPO system. High power MIR emission was generated with average output power of 5.15 W at 3.8 ?m channel and 8.54 W at 3.3 ?m channel under the highest pump power of 45 W. The corresponding pump-to-idler conversion efficiency was computed to be 11.7% and 19.1%, respectively. Experimental results verify a significant improvement to signal-to-idler conversion efficiency by using "figure-of-h" pulses over simple pedestal-free pulses. Compared to the master oscillator power amplifier (MOPA) fiber laser counterpart, the presented gain switched fiber laser is more attractive in OPO pumping due to its compactness and simplicity which are beneficial to construction of OPO systems for practical MIR applications. PMID:25836126

  20. Weight Gain during Pregnancy

    MedlinePLUS

    ... this page It's been added to your dashboard . Weight gain during pregnancy When you’re pregnant, you ... in sight! Be careful about the amount of weight you gain during your pregnancy. Gaining too much ...

  1. High-Fat-Diet-Induced Weight Gain Ameliorates Bone Loss without Exacerbating A?PP Processing and Cognition in Female APP/PS1 Mice

    PubMed Central

    Peng, Yunhua; Liu, Jing; Tang, Ying; Liu, Jianshu; Han, Tingting; Han, Shujun; Li, Hua; Hou, Chen; Liu, Jiankang; Long, Jiangang

    2014-01-01

    Osteoporosis is negatively correlated with body mass, whereas both osteoporosis and weight loss occur at higher incidence during the progression of Alzheimer’s disease (AD) than the age-matched non-dementia individuals. Given that there is no evidence that being overweight is associated with AD-type cognitive dysfunction, we hypothesized that moderate weight gain might have a protective effect on the bone loss in AD without exacerbating cognitive dysfunction. In this study, feeding a high-fat diet (HFD, 45% calorie from fat) to female APP/PS1 transgenic mice, an AD animal model, induced weight gain. The bone mineral density, microarchitecture, and biomechanical properties of the femurs were then evaluated. The results showed that the middle-aged female APP/PS1 transgenic mice were susceptible to osteoporosis of the femoral bones and that weight gain significantly enhanced bone mass and mechanical properties. Notably, HFD was not detrimental to brain insulin signaling and A?PP processing, as well as to exploration ability and working, learning, and memory performance of the transgenic mice measured by T maze and Morris water maze, compared with the mice fed a normal-fat diet (10% calorie from fat). In addition, the circulating levels of leptin but not estradiol were remarkably elevated in HFD-treated mice. These results suggest that a body weight gain induced by the HFD feeding regimen significantly improved bone mass in female APP/PS1 mice with no detriments to exploration ability and spatial memory, most likely via the action of elevated circulating leptin. PMID:25152713

  2. JUNGFRAU 0.2: prototype characterization of a gain-switching, high dynamic range imaging system for photon science at SwissFEL and synchrotrons

    NASA Astrophysics Data System (ADS)

    Jungmann-Smith, J. H.; Bergamaschi, A.; Cartier, S.; Dinapoli, R.; Greiffenberg, D.; Johnson, I.; Maliakal, D.; Mezza, D.; Mozzanica, A.; Ruder, Ch; Schaedler, L.; Schmitt, B.; Shi, X.; Tinti, G.

    2014-12-01

    JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional pixel detector for photon science applications at free electron lasers and synchrotron light sources. It is developed for the SwissFEL currently under construction at the Paul Scherrer Institute, Switzerland. Characteristics of this application-specific integrating circuit readout chip include single photon sensitivity and low noise over a dynamic range of over four orders of magnitude of photon input signal. These characteristics are achieved by a three-fold gain-switching preamplifier in each pixel, which automatically adjusts its gain to the amount of charge deposited on the pixel. The final JUNGFRAU chip comprises 256 × 256 pixels of 75 × 75 ?m2 each. Arrays of 2 × 4 chips are bump-bonded to monolithic detector modules of about 4 × 8 cm2. Multi-module systems up to 16 Mpixels are planned for the end stations at SwissFEL. A readout rate in excess of 2 kHz is anticipated, which serves the readout requirements of SwissFEL and enables high count rate synchrotron experiments with a linear count rate capability of > 20 MHz/pixel. Promising characterization results from a 3.6 × 3.6 mm2 prototype (JUNGFRAU 0.2) with fluorescence X-ray, infrared laser and synchrotron irradiation are shown. The results include an electronic noise as low as 100 electrons root-mean-square, which enables single photon detection down to X-ray energies of about 2 keV. Noise below the Poisson fluctuation of the photon number and a linearity error of the pixel response of about 1% are demonstrated. First imaging experiments successfully show automatic gain switching. The edge spread function of the imaging system proves to be comparable in quality to single photon counting hybrid pixel detectors.

  3. Mice with Low Metabolic Rates Are Not Susceptible to Weight Gain When Fed a High-Fat Diet

    Microsoft Academic Search

    Catherine Hambly; Andrew Adams; Jean-Michel Fustin; Kellie A. Rance; Lutz Bünger; John R. Speakman

    2005-01-01

    Objective: Mice divergently selected for high or low food intake (FI) at constant body mass differ in their resting metabolic rates (RMRs). Low-intake individuals (ML) have significantly lower RMR (by 30%) compared with those from the high-intake line (MH). We hypothesized that MLs might, therefore, be more likely to increase their body and fat mass when exposed to a high-fat

  4. Black and Hispanic Charter Students More Likely to Gain Admission to Selective NYC High Schools. Issue Brief No. 4

    ERIC Educational Resources Information Center

    Winters, Marcus A.

    2010-01-01

    A recent review of data provided by the New York City Department of Education reveals that African-American charter school students were 60 percent more likely than their public school counterparts to earn a seat in one of New York City's specialized high schools in 2009. For Hispanics, the rate of acceptance was twice as high for charter school…

  5. Novel high-gain, improved-bandwidth, finned-ladder V-band Traveling-Wave Tube slow-wave circuit design

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.; Wilson, Jeffrey D.

    1994-01-01

    The V-band frequency range of 59-64 GHz is a region of the millimeter-wave spectrum that has been designated for inter-satellite communications. As a first effort to develop a high-efficiency V-band Traveling-Wave Tube (TWT), variations on a ring-plane slow-wave circuit were computationally investigated to develop an alternative to the more conventional ferruled coupled-cavity circuit. The ring-plane circuit was chosen because of its high interaction impedance, large beam aperture, and excellent thermal dissipation properties. Despite these advantages, however, low bandwidth and high voltage requirements have, until now, prevented its acceptance outside the laboratory. In this paper, the three-dimensional electrodynamic simulation code MAFIA (solution of MAxwell's Equation by the Finite-Integration-Algorithm) is used to investigate methods of increasing the bandwidth and lowering the operating voltage of the ring-plane circuit. Calculations of frequency-phase dispersion, beam on-axis interaction impedance, attenuation and small-signal gain per wavelength were performed for various geometric variations and loading distributions of the ring-plane TWT slow-wave circuit. Based on the results of the variations, a circuit termed the finned-ladder TWT slow-wave circuit was designed and is compared here to the scaled prototype ring-plane and a conventional ferruled coupled-cavity TWT circuit over the V-band frequency range. The simulation results indicate that this circuit has a much higher gain, significantly wider bandwidth, and a much lower voltage requirement than the scaled ring-plane prototype circuit, while retaining its excellent thermal dissipation properties. The finned-ladder circuit has a much larger small-signal gain per wavelength than the ferruled coupled-cavity circuit, but with a moderate sacrifice in bandwidth.

  6. Transcriptional changes associated with reduced spontaneous liver tumor incidence in mice chronically exposed to high dose arsenic.

    PubMed

    Nelson, Gail M; Ahlborn, Gene J; Allen, James W; Ren, Hongzu; Corton, J Christopher; Waalkes, Michael P; Kitchin, Kirk T; Diwan, Bhalchandra A; Knapp, Geremy; Delker, Don A

    2009-12-21

    Exposure of male C3H mice in utero (from gestational days 8-18) to 85ppm sodium arsenite via the dams' drinking water has previously been shown to increase liver tumor incidence by 2 years of age. However, in our companion study (Ahlborn et al., 2009), continuous exposure to 85ppm sodium arsenic (from gestational day 8 to postnatal day 365) did not result in increased tumor incidence, but rather in a significant reduction (0% tumor incidence). The purpose of the present study was to examine the gene expression responses that may lead to the apparent protective effect of continuous arsenic exposure. Genes in many functional categories including cellular growth and proliferation, gene expression, cell death, oxidative stress, protein ubiquitination, and mitochondrial dysfunction were altered by continuous arsenic treatment. Many of these genes are known to be involved in liver cancer. One such gene associated with rodent hepatocarcinogenesis, Scd1, encodes stearoyl-CoA desaturase and was down-regulated by continuous arsenic treatment. An overlap between the genes in our study affected by continuous arsenic exposure and those from the literature affected by long-term caloric restriction suggests that reduction in the spontaneous tumor incidence under both conditions may involve similar gene pathways such as fatty acid metabolism, apoptosis, and stress response. PMID:19822182

  7. High-gain effects minimized at the ends of the anodes in position sensitive gas proportional counters for SSM on ASTROSAT

    NASA Astrophysics Data System (ADS)

    Ramadevi, M. C.; Babu, V. C.; Ashoka, B. N.; Seetha, S.

    2014-12-01

    The Scanning Sky Monitor (SSM) on ASTROSAT is a position-sensitive gas-filled proportional counter with a wide field of view. The science objective of SSM is to scan the sky to detect and locate transient X-ray sources in the outburst phase. The energy range of operation of SSM is 2.5 to 10 keV. Gas-filled proportional counters are known to have distorted electric fields at the ends of the anodes inside the detector. The electric field and hence the gas gain is different at the ends of the anodes compared to that of the central region. In SSM, the ends of the anode wires were found to have high electric field values and hence high gas gain initially. These effects had to be minimized as they would result in huge charge collection for incidence of highly energetic photons and charged particles, leading to probable discharge effects which would limit the life time of the detector. They also result in undesirable signals, the amplitude of which may not be proportional to the energy of the incident photon. In this paper, we discuss the technique which we use to reduce the field at the ends of the anodes in SSM detectors.

  8. Porcine Adiponectin Receptor 1 Transgene Resists High-fat/Sucrose Diet-Induced Weight Gain, Hepatosteatosis and Insulin Resistance in Mice

    PubMed Central

    Liu, Bing-Hsien; Lin, Yuan-Yu; Wang, Ya-Chin; Huang, Chao-Wei; Chen, Chih-Chien; Wu, Shinn-Chih; Mersmann, Harry J.; Cheng, Winston T.K.; Ding, Shih-Torng

    2013-01-01

    Adiponectin and its receptors have been demonstrated to play important roles in regulating glucose and lipid metabolism in mice. Obesity, type II diabetes and cardiovascular disease are highly correlated with down-regulated adiponectin signaling. In this study, we generated mice overexpressing the porcine Adipor1 transgene (pAdipor1) to study its beneficial effects in metabolic syndromes as expressed in diet-induced obesity, hepatosteatosis and insulin resistance. Wild-type (WT) and pAdipor1 transgenic mice were fed ad libitum with a standard chow diet (Chow) or a high-fat/sucrose diet (HFSD) for 24 weeks, beginning at 6 to 7 weeks of age. There were 12 mice per genetic/diet/sex group. When challenged with HFSD to induce obesity, the pAdipor1 transgenic mice resisted development of weight gain, hepatosteatosis and insulin resistance. These mice had lowered plasma adiponectin, triglyceride and glycerol concentrations compared to WT mice. Moreover, we found that (indicated by mRNA levels) fatty acid oxidation was enhanced in skeletal muscle and adipose tissue, and liver lipogenesis was inhibited. The pAdipor1 transgene also restored HFSD-reduced phosphoenolpyruvate carboxykinase 1 (Pck1) and glucose transporter 4 mRNA in the adipose tissues, implying that the increased Pck1 may promote glyceroneogenesis to reduce glucose intolerance and thus activate the flux of glyceride-glycerol to resist diet-induced weight gain in the adipose tissues. Taken together, we demonstrated that pAdipor1 can prevent diet-induced weight gain and insulin resistance. Our findings may provide potential therapeutic strategies for treating metabolic syndromes and obesity, such as treatment with an ADIPOR1 agonist or activation of Adipor1 downstream targets. PMID:24172199

  9. How Much Professional Development Is Needed to Effect Positive Gains in K-6 Student Achievement on High Stakes Science Tests?

    ERIC Educational Resources Information Center

    Shymansky, James A.; Wang, Tzu-Ling; Annetta, Leonard A.; Yore, Larry D.; Everett, Susan A.

    2012-01-01

    This paper is a report of a study that examines the relationship between teacher participation in a multi-year, K-6 professional development effort and the "high stakes" science test scores of different student groups in 33 rural mid-west school districts in the USA. The professional development program involved 1,269 elementary school teachers…

  10. Three Months of High-Fructose Feeding Fails to Induce Excessive Weight Gain or Leptin Resistance in Mice

    PubMed Central

    Tillman, Erik J.; Morgan, Donald A.; Rahmouni, Kamal; Swoap, Steven J.

    2014-01-01

    High-fructose diets have been implicated in obesity via impairment of leptin signaling in humans and rodents. We investigated whether fructose-induced leptin resistance in mice could be used to study the metabolic consequences of fructose consumption in humans, particularly in children and adolescents. Male C57Bl/6 mice were weaned to a randomly assigned diet: high fructose, high sucrose, high fat, or control (sugar-free, low-fat). Mice were maintained on their diets for at least 14 weeks. While fructose-fed mice regularly consumed more kcal and expended more energy, there was no difference in body weight compared to control by the end of the study. Additionally, after 14 weeks, both fructose-fed and control mice displayed similar leptin sensitivity. Fructose-feeding also did not change circulating glucose, triglycerides, or free fatty acids. Though fructose has been linked to obesity in several animal models, our data fail to support a role for fructose intake through food lasting 3 months in altering of body weight and leptin signaling in mice. The lack of impact of fructose in the food of growing mice on either body weight or leptin sensitivity over this time frame was surprising, and important information for researchers interested in fructose and body weight regulation. PMID:25211467

  11. High Magnetic Shear Gain in a Liquid Sodium Stable Couette Flow Experiment: A Prelude to an alpha-Omega Dynamo

    Microsoft Academic Search

    Stirling A. Colgate; Howard Beckley; Jiahe Si; Joe Martinic; David Westpfahl; James Slutz; Cebastian Westrom; Brianna Klein; Paul Schendel; Cletus Scharle; Travis McKinney; Rocky Ginanni; Ian Bentley; Timothy Mickey; Regnar Ferrel; Hui Li; Vladimir Pariev; John Finn

    2011-01-01

    The Omega phase of the liquid sodium alpha-Omega dynamo experiment at New Mexico Institute of Mining and Technology in cooperation with Los Alamos National Laboratory has demonstrated a high toroidal field Bvarphi that is ~=8×Br, where Br is the radial component of an applied poloidal magnetic field. This enhanced toroidal field is produced by the rotational shear in stable Couette

  12. Gathering Feedback for Teaching: Combining High-Quality Observations with Student Surveys and Achievement Gains. Research Paper. MET Project

    ERIC Educational Resources Information Center

    Kane, Thomas J.; Staiger, Douglas O.

    2012-01-01

    There is a growing consensus that teacher evaluation in the United States is fundamentally broken. Few would argue that a system that tells 98 percent of teachers they are "satisfactory" benefits anyone--including teachers. The nation's collective failure to invest in high-quality professional feedback to teachers is inconsistent with decades of…

  13. High Magnetic Shear Gain in a Liquid Sodium Stable Couette Flow Experiment: A Prelude to an - Dynamo

    Microsoft Academic Search

    Stirling A. Colgate; Howard Beckley; Jiahe Si; Joe Martinic; David Westpfahl; James Slutz; Cebastian Westrom; Brianna Klein; Paul Schendel; Cletus Scharle; Travis McKinney; Rocky Ginanni; Ian Bentley; Timothy Mickey; Regnar Ferrel; Hui Li; Vladimir Pariev; John Finn

    2011-01-01

    The phase of the liquid sodium - dynamo experiment at New Mexico Institute of Mining and Technology in cooperation with Los Alamos National Laboratory has demonstrated a high toroidal field B{sub } that is 8xB{sub r}, where B{sub r} is the radial component of an applied poloidal magnetic field. This enhanced toroidal field is produced by the rotational shear in

  14. Spectroscopic and microscopic studies of self-assembled nc-Si/a-SiC thin films grown by low pressure high density spontaneous plasma processing.

    PubMed

    Das, Debajyoti; Kar, Debjit

    2014-12-14

    In view of suitable applications in the window layer of nc-Si p-i-n solar cells in superstrate configuration, the growth of nc-Si/a-SiC composite films was studied, considering the trade-off relation between individual characteristics of its a-SiC component to provide a wide optical-gap and electrically conducting nc-Si component to simultaneously retain enough crystalline linkages to facilitate proper crystallization to the i-nc-Si absorber-layer during its subsequent growth. Self-assembled nc-Si/a-SiC thin films were spontaneously grown by low-pressure planar inductively coupled plasma CVD, operating in electromagnetic mode, providing high atomic-H density. Spectroscopic simulations of ellipsometry and Raman data, and systematic chemical and structural analysis by XPS, TEM, SEM and AFM were performed. Corresponding to optimized inclusion of C essentially incorporated as Si-C bonds in the network, the optical-gap of the a-SiC component widened, void fraction including the incubation layer thickness reduced. While the bulk crystallinity decreased only marginally, Si-ncs diminished in size with narrower distribution and increased number density. With enhanced C-incorporation, formation of C-C bonds in abundance deteriorates the Si continuous bonding network and persuades growth of an amorphous dominated silicon-carbon heterostructure containing high-density tiny Si-ncs. Stimulated nanocrystallization identified in the Si-network, induced by a limited amount of carbon incorporation, makes the material most suitable for applications in nc-Si solar cells. The novelty of the present work is to enable spontaneous growth of self-assembled superior quality nc-Si/a-SiC thin films and simultaneous spectroscopic simulation-based optimization of properties for utilization in devices. PMID:25342429

  15. High magnetic shear gain in a liquid sodium stable Couette flow experiment: a prelude to an ?-? dynamo.

    PubMed

    Colgate, Stirling A; Beckley, Howard; Si, Jiahe; Martinic, Joe; Westpfahl, David; Slutz, James; Westrom, Cebastian; Klein, Brianna; Schendel, Paul; Scharle, Cletus; McKinney, Travis; Ginanni, Rocky; Bentley, Ian; Mickey, Timothy; Ferrel, Regnar; Li, Hui; Pariev, Vladimir; Finn, John

    2011-04-29

    The ? phase of the liquid sodium ?-? dynamo experiment at New Mexico Institute of Mining and Technology in cooperation with Los Alamos National Laboratory has demonstrated a high toroidal field B(?) that is ?8×B(r), where B(r) is the radial component of an applied poloidal magnetic field. This enhanced toroidal field is produced by the rotational shear in stable Couette flow within liquid sodium at a magnetic Reynolds number Rm?120. Small turbulence in stable Taylor-Couette flow is caused by Ekman flow at the end walls, which causes an estimated turbulence energy fraction of (?v/v)(2)?10(-3). PMID:21635041

  16. High Magnetic Shear Gain in a Liquid Sodium Stable Couette Flow Experiment: A Prelude to an {alpha}-{Omega} Dynamo

    SciTech Connect

    Colgate, Stirling A. [T-2, MS B-227, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Physics, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801 (United States); Beckley, Howard; Si, Jiahe; Martinic, Joe; Westpfahl, David; Slutz, James; Westrom, Cebastian; Klein, Brianna; Schendel, Paul; Scharle, Cletus; McKinney, Travis; Ginanni, Rocky; Bentley, Ian; Mickey, Timothy; Ferrel, Regnar [Department of Physics, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801 (United States); Li, Hui; Pariev, Vladimir [T-2, MS B-227, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Finn, John [T-5, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2011-04-29

    The {Omega} phase of the liquid sodium {alpha}-{Omega} dynamo experiment at New Mexico Institute of Mining and Technology in cooperation with Los Alamos National Laboratory has demonstrated a high toroidal field B{sub {phi}} that is {approx_equal}8xB{sub r}, where B{sub r} is the radial component of an applied poloidal magnetic field. This enhanced toroidal field is produced by the rotational shear in stable Couette flow within liquid sodium at a magnetic Reynolds number Rm{approx_equal}120. Small turbulence in stable Taylor-Couette flow is caused by Ekman flow at the end walls, which causes an estimated turbulence energy fraction of ({delta}v/v){sup 2{approx}}10{sup -3}.

  17. New insights into hydrochemical processes in lowland river systems gained from in situ, high-resolution monitoring

    NASA Astrophysics Data System (ADS)

    Wade, Andrew; Palmer-Felgate, Elizabeth; Halliday, Sarah; Skeffington, Richard; Loewenthal, Matthew; Jarvie, Helen; Bowes, Michael; Greenway, Gillian; Haswell, Stephen; Bell, Ian; Joly, Etienne; Fallatah, Ahmed; Neal, Colin; Williams, Richard; Gozzard, Emma; Newman, Jonathan

    2013-04-01

    This work focuses on the insights obtained from in situ, high-resolution hydrochemical monitoring in three lowland UK catchments experiencing different levels of nutrient enrichment. Between November 2009 and February 2012, the upper River Kennet, the River Enborne and The Cut, all located within the Thames basin, southeast England, were instrumented with in situ analytical equipment to make hourly measurements of a range of hydrochemical determinands. The upper River Kennet is a rural catchment with limited effluent inputs above the selected monitoring point. The River Enborne is a rural catchment, impacted by agricultural runoff, and septic tank and sewage treatment works (STWs) discharges. The Cut is a highly urbanised system significantly affected by STW discharges. On the upper River Kennet and the River Enborne hourly measurements of Total Reactive Phosphorus (TRP) were made using a Systea Micromac C. In addition on the River Enborne, a Hach Lange Nitratax was used to measure nitrate (NO3). On The Cut both Total P and TRP were measured using a Hach Lange Phosphax Sigma. At all stations nutrient monitoring was supplemented with hourly pH, chlorophyll, dissolved oxygen, conductivity, turbidity and water temperature using YSI 6600 Multi-parameter sondes. Instream hydrochemical dynamics were investigated using non-stationary time-series analysis techniques. The results reveal complex nutrient dynamics, with diurnal patterns which exhibit seasonal changes in phase and amplitude, and are influenced by flow conditions, shading and nutrient sources. On the River Enborne a marked diurnal cycle was present within the streamwater NO3 time-series. The cycle was strongest in the spring before riparian shading developed. At times of low flow a two peak diurnal cycle was also evident in the streamwater NO3 time-series. The reduction in diurnal NO3 processing after the development of riparian shading was also accompanied by a marked drop in dissolved oxygen at this time. The presence of a two peak diurnal cycle is indicative of the dominance of STW discharges to the system, as STW discharges exhibit a marked two peak diurnal cycle associated with peak water usage. This two peak diurnal cycling can also been seen in the River Enborne TRP data. The dominance of effluent discharges was also evident in the River Enborne seasonal NO3 and TRP dynamics. Both determinands displayed summer time peaks caused by the reduced dilution capacity of the system and increased water residence time during the low flow summer months. The TP and TRP dynamics on The Cut were highly complex with significant diurnal fluctuations. Although, a two peak diurnal signal was evident within the TRP time-series it was difficult to characterise due to the complexity of the dynamics observed. Monitoring on the upper River Kennet highlighted the challenges associated with undertaking in situ analytical monitoring without mains electricity. Resampling of the data at lower sampling frequencies demonstrated that within the point-source dominated catchments, daily monitoring was sufficient for accurate load estimation.

  18. High guided mode-cavity mode coupling for an efficient extraction of spontaneous emission of a single quantum dot embedded in a photonic crystal nanobeam cavity

    NASA Astrophysics Data System (ADS)

    Enderlin, Alexandre; Ota, Yasutomo; Ohta, Ryuichi; Kumagai, Naoto; Ishida, Satomi; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2012-08-01

    We demonstrate efficient extraction of a single InAs quantum dot spontaneous emission through an air-suspended waveguide to which a photonic crystal nanobeam cavity is coupled. First, the quantum dot emission into the cavity mode is enhanced due to a high Purcell effect arising from a large quality factor and a small mode volume of the cavity mode. Second, the cavity photons can be efficiently transferred to the guided mode by optimizing the design of a structure that exhibits a high coupling rate between the two modes. This configuration has lead to the observation of a high extraction efficiency (79%) of the quantum dot emission through the waveguide. Moreover, as a result of the high extraction efficiency to the guided mode, the unwanted microphotoluminescence coupling to the free space modes and detected from the top surface of the sample is strongly suppressed. Indeed, we show that it exhibits a negative peak as a function of the detuning between the cavity mode energy and the quantum dot transition energy.

  19. Preventing Weight Gain

    MedlinePLUS

    ... a diet, it's a lifestyle! Share Compartir Preventing Weight Gain If you're currently at a healthy ... of cancer. Choosing an Eating Plan to Prevent Weight Gain So, how do you choose a healthful ...

  20. A mitochondrial-targeted coenzyme q analog prevents weight gain and ameliorates hepatic dysfunction in high-fat-fed mice.

    PubMed

    Fink, Brian D; Herlein, Judith A; Guo, Deng Fu; Kulkarni, Chaitanya; Weidemann, Benjamin J; Yu, Liping; Grobe, Justin L; Rahmouni, Kamal; Kerns, Robert J; Sivitz, William I

    2014-12-01

    We hypothesized that the mitochondrial-targeted antioxidant, mitoquinone (mitoQ), known to have mitochondrial uncoupling properties, might prevent the development of obesity and mitigate liver dysfunction by increasing energy expenditure, as opposed to reducing energy intake. We administered mitoQ or vehicle (ethanol) to obesity-prone C57BL/6 mice fed high-fat (HF) or normal-fat (NF) diets. MitoQ (500 µM) or vehicle (ethanol) was added to the drinking water for 28 weeks. MitoQ significantly reduced total body mass and fat mass in the HF-fed mice but had no effect on these parameters in NF mice. Food intake was reduced by mitoQ in the HF-fed but not in the NF-fed mice. Average daily water intake was reduced by mitoQ in both the NF- and HF-fed mice. Hypothalamic expression of neuropeptide Y, agouti-related peptide, and the long form of the leptin receptor were reduced in the HF but not in the NF mice. Hepatic total fat and triglyceride content did not differ between the mitoQ-treated and control HF-fed mice. However, mitoQ markedly reduced hepatic lipid hydroperoxides and reduced circulating alanine aminotransferase, a marker of liver function. MitoQ did not alter whole-body oxygen consumption or liver mitochondrial oxygen utilization, membrane potential, ATP production, or production of reactive oxygen species. In summary, mitoQ added to drinking water mitigated the development of obesity. Contrary to our hypothesis, the mechanism involved decreased energy intake likely mediated at the hypothalamic level. MitoQ also ameliorated HF-induced liver dysfunction by virtue of its antioxidant properties without altering liver fat or mitochondrial bioenergetics. PMID:25301169

  1. Exercise Prevents Weight Gain and Alters the Gut Microbiota in a Mouse Model of High Fat Diet-Induced Obesity

    PubMed Central

    Evans, Christian C.; LePard, Kathy J.; Kwak, Jeff W.; Stancukas, Mary C.; Laskowski, Samantha; Dougherty, Joseph; Moulton, Laura; Glawe, Adam; Wang, Yunwei; Leone, Vanessa; Antonopoulos, Dionysios A.; Smith, Dan; Chang, Eugene B.; Ciancio, Mae J.

    2014-01-01

    Background Diet-induced obesity (DIO) is a significant health concern which has been linked to structural and functional changes in the gut microbiota. Exercise (Ex) is effective in preventing obesity, but whether Ex alters the gut microbiota during development with high fat (HF) feeding is unknown. Objective Determine the effects of voluntary Ex on the gastrointestinal microbiota in LF-fed mice and in HF-DIO. Methods Male C57BL/6 littermates (5 weeks) were distributed equally into 4 groups: low fat (LF) sedentary (Sed) LF/Sed, LF/Ex, HF/Sed and HF/Ex. Mice were individually housed and LF/Ex and HF/Ex cages were equipped with a wheel and odometer to record Ex. Fecal samples were collected at baseline, 6 weeks and 12 weeks and used for bacterial DNA isolation. DNA was subjected both to quantitative PCR using primers specific to the 16S rRNA encoding genes for Bacteroidetes and Firmicutes and to sequencing for lower taxonomic identification using the Illumina MiSeq platform. Data were analyzed using a one or two-way ANOVA or Pearson correlation. Results HF diet resulted in significantly greater body weight and adiposity as well as decreased glucose tolerance that were prevented by voluntary Ex (p<0.05). Visualization of Unifrac distance data with principal coordinates analysis indicated clustering by both diet and Ex at week 12. Sequencing demonstrated Ex-induced changes in the percentage of major bacterial phyla at 12 weeks. A correlation between total Ex distance and the ?Ct Bacteroidetes: ?Ct Firmicutes ratio from qPCR demonstrated a significant inverse correlation (r2?=?0.35, p?=?0.043). Conclusion Ex induces a unique shift in the gut microbiota that is different from dietary effects. Microbiota changes may play a role in Ex prevention of HF-DIO. PMID:24670791

  2. Spaceliner Class Operability Gains Via Combined Airbreathing/ Rocket Propulsion: Summarizing an Operational Assessment of Highly Reusable Space Transports

    NASA Technical Reports Server (NTRS)

    Nix, Michael B.; Escher, William J. d.

    1999-01-01

    In discussing a new NASA initiative in advanced space transportation systems and technologies, the Director of the NASA Marshall Space Flight Center, Arthur G. Stephenson, noted that, "It would use new propulsion technology, air-breathing engine so you don't have to carry liquid oxygen, at least while your flying through the atmosphere. We are calling it Spaceliner 100 because it would be 100 times cheaper, costing $ 100 dollars a pound to orbit." While airbreathing propulsion is directly named, rocket propulsion is also implied by, "... while you are flying through the atmosphere." In-space final acceleration to orbital speed mandates rocket capabilities. Thus, in this informed view, Spaceliner 100 will be predicated on combined airbreathing/rocket propulsion, the technical subject of this paper. Interestingly, NASA's recently concluded Highly Reusable Space Transportation (HRST) study focused on the same affordability goal as that of the Spaceliner 100 initiative and reflected the decisive contribution of combined propulsion as a way of expanding operability and increasing the design robustness of future space transports, toward "aircraft like" capabilities. The HRST study built on the Access to Space Study and the Reusable Launch Vehicle (RLV) development activities to identify and characterize space transportation concepts, infrastructure and technologies that have the greatest potential for reducing delivery cost by another order of magnitude, from $1,000 to $100-$200 per pound for 20,000 lb. - 40.000 lb. payloads to low earth orbit (LEO). The HRST study investigated a number of near-term, far-term, and very far-term launch vehicle concepts including all-rocket single-stage-to-orbit (SSTO) concepts, two-stage-to-orbit (TSTO) concepts, concepts with launch assist, rocket-based combined cycle (RBCC) concepts, advanced expendable vehicles, and more far term ground-based laser powered launchers. The HRST study consisted of preliminary concept studies, assessments and analysis tool development for advanced space transportation systems, followed by end-to-end system concept definitions and trade analyses, specific system concept definition and analysis, specific key technology and topic analysis, system, operational and economics model development, analysis, and integrated assessments. The HRST Integration Task Force (HITF) was formed to synthesize study results in several specific topic areas and support the development of conclusions from the study: Systems Concepts Definitions, Technology Assessment, Operations Assessment, and Cost Assessment. This paper summarizes the work of the Operations Assessment Team: the six approaches used, the analytical tools and methodologies developed and employed, the issues and concerns, and the results of the assessment. The approaches were deliberately varied in measures of merit and procedure to compensate for the uncertainty inherent in operations data in this early phase of concept exploration. In general, rocket based combined cycle (RBCC) concepts appear to have significantly greater potential than all-rocket concepts for reducing operations costs.

  3. Whey-reduced weight gain is associated with a temporary growth reduction in young mice fed a high-fat diet.

    PubMed

    Tranberg, Britt; Madsen, Andreas N; Hansen, Axel K; Hellgren, Lars I

    2015-01-01

    Whey protein consumption reportedly alleviates parameters of the metabolic syndrome. Here, we investigated the effects of whey protein isolate (whey) in young mice fed a high-fat diet. We hypothesized that whey as the sole protein source reduced early weight gain associated with retarded growth and decreased concentration of insulin-like growth factor-1. Moreover, we hypothesized that these changes were explained by increased nitrogen loss via elevated urea production and/or increased energy expenditure. Male 5-week-old C57BL/6 mice were fed high-fat diets with the protein source being either whey, casein or a combination of both for 5 weeks. After 1, 3 or 5 weeks, respectively, the mice were subjected to a meal challenge with measurements of blood and urinary urea before and 1 and 3 h after eating a weighed meal of their respective diets. In a subset of mice, energy expenditure was measured by indirect calorimetry during the first week of dietary intervention. Observed exclusively during the first week of intervention, whey significantly reduced body length (P<.01) and weight gain (P<.001) correlating positively with plasma concentrations of insulin-like growth factor-1. The combination diet displayed intermediate results indicating an interactive effect. Urea production, urea cycle activity, food intake and energy expenditure were unaffected by protein source. In conclusion, whey decreased growth-related parameters exclusively during the first week of dietary intervention. The early effect of whey could not be explained by food intake, energy expenditure, urea production or urea cycle activity but was correlated with plasma levels of insulin-like growth factor-1. PMID:25315863

  4. Gain of the triceps surae stretch reflex in decerebrate and spinal cats during postural and locomotor activities.

    PubMed Central

    Bennett, D J; De Serres, S J; Stein, R B

    1996-01-01

    1. The triceps surae (TS) stretch reflex was measured in decerebrate cats during crossed extensor stimulation and after spinalization during rhythmic locomotor activity induced by clonidine and manual perineal stimulation. The TS force in response to sinusoidal stretch was measured at a given contraction level before and after deafferentation, and the 'reflex force' was computed by subtracting these two responses. Reflex 'gain' was computed as the ratio of the reflex and deafferented force responses (a unitless estimate of the open loop feedback gain). 2. Prior to locomotion the spontaneous muscle activity was low (less than 15% of maximum), but the reflex gain was relatively high (close to 1.0 with a 5 Hz stretch). When locomotion commenced the reflex gain was markedly lowered when measured at the same contraction level as before locomotion (25% of the gain prior to locomotion). At higher contraction levels the reflex gain was not significantly increased. The reflex force and EMG responses to stretch increased with the contraction level, but their effect on the total reflex gain was cancelled by an associated increase in the intrinsic muscle stiffness. 3. In the decerebrate cat, during weak tonic contractions (spontaneous), the reflex gain was high and comparable with the gain in the resting spinal cat. However, with increased tonic contractions produced by crossed extensor stimulation the reflex gain dropped. At higher contraction levels the gain was not significantly different from the gain during spinal locomotion. 4. When the frequency of stretch was increased from 3 to 20 Hz, EMG responses to stretch increased, but the reflex force decreased, since a more fused contraction developed with the more frequent reflex activations. Overall, the reflex gain decreased with frequency in both spinal and decerebrate cats. The phase lag of the reflex force, relative to the intrinsic muscle force, increased with increasing frequency, due to reflex delays, with a 180 deg lag occurring between 12 and 18 Hz (tremor frequencies). The mean gain was significantly lower and the phase lag was significantly greater during locomotion than during tonic crossed extensor contractions, suggesting different reflex mechanisms. 5. In conclusion, during locomotion in spinal cats afferent feedback from low frequency ankle movements, similar to those occurring during the normal step cycle, reflexly produces a small but significant fraction of the extensor force (about a quarter of the stretch-related force modulation). This fraction is remarkably constant at the different contraction levels of the step cycle. Afferent feedback during higher frequency movement is less effective, minimizing the chance of instability and tremor. In contrast during tonic contractions afferent feedback produces half of the total muscle force during perturbations, clearly contributing to the maintenance of posture. PMID:8930848

  5. Spontaneous Spinal Subarachnoid Hemorrhage with Spontaneous Resolution

    PubMed Central

    Lee, Sang-Ho

    2009-01-01

    Spontaneous spinal subarachnoid hematoma (SSH) is a rare entity to cause spinal cord or nerve root compression and is usually managed as surgical emergencies. We report a case of spontaneous SSH manifesting as severe lumbago, which demonstrated nearly complete clinical resolution with conservative treatment. A 58-year-old female patient developed a large SSH, which was not related to blood dyscrasia, anticoagulation, lumbar puncture, or trauma. Patient had severe lumbago but no neurologic deficits. Because of absence of neurologicl deficits, she was treated conservatively. Follow-up magnetic resonance (MR) image showed complete resolution. Conservative treatment of SSH may be considered if the patient with spontaneous SSH has no neurologic deficits. PMID:19444355

  6. Statistical analysis of the chaotic optical field from a self-amplified spontaneous-emission free-electron laser

    NASA Astrophysics Data System (ADS)

    Krinsky, S.; Li, Y.

    2006-06-01

    We use Rice’s theory of shot noise random processes to provide a statistical analysis of the evolution of the amplitude and phase of the chaotic optical field from a high-gain, self-amplified, spontaneous-emission (SASE) free-electron laser. The theoretical framework developed is compared with recent frequency-resolved optical-gating measurements of the SASE output at the LEUTL facility at Argonne National Laboratory.

  7. Current Biology 21, 306310, February 22, 2011 2011 Elsevier Ltd All rights reserved DOI 10.1016/j.cub.2011.01.026 High Spontaneous Rate of Gene

    E-print Network

    Lynch, Michael

    hybridization yields the first direct estimate of the genome-wide rate of gene duplication in a multicellular.cub.2011.01.026 Report High Spontaneous Rate of Gene Duplication in Caenorhabditis elegans Kendra J of Biology, Indiana University, Bloomington, IN 47405, USA Summary Gene and genome duplications

  8. Effects of a High-Fat Diet on Spontaneous Metastasis of Lewis Lung Carcinoma in Plasminogen Activator Inhibitor-1 Deficient and Wild-Type Mice

    PubMed Central

    Yan, Lin; DeMars, Lana C.

    2014-01-01

    This study investigated the effects of a high-fat diet on spontaneous metastasis of Lewis lung carcinoma (LLC) in plasminogen activator inhibitor-1 deficient (PAI-1?/?) and wild-type mice. The high-fat diet increased the number of pulmonary metastases by 60% (p<0.01), tumor cross-sectional area by 82% (p<0.05) and tumor volume by 130% (p<0.05) compared to the AIN93G diet. Deficiency in PAI-1 reduced the number of metastases by 35% (p<0.01) compared to wild-type mice. In mice fed the high-fat diet, PAI-1 deficiency reduced tumor cross-sectional area by 52% (p<0.05) and tumor volume by 61% (p<0.05) compared to their wild-type counterparts; however, PAI-1 deficiency affected neither area nor volume in mice fed the AIN93G diet. Adipose and plasma concentrations of PAI-1 were significantly higher in high-fat fed wild-type mice than in their AIN93G-fed counterparts. Adipose and plasma PAI-1 were not detectable in PAI-1?/? mice regardless of the diet. Mice deficient in PAI-1 showed significantly greater plasma concentrations of monocyte chemotactic protein-1, tumor necrosis factor-?, leptin, vascular endothelial growth factor, tissue inhibitor of metalloproteinase-1 and insulin compared to wild-type mice, indicating a compensatory overproduction of inflammatory cytokines, angiogenic factors and insulin in the absence of PAI-1. We conclude that PAI-1 produced by the host, including that by adipose tissue, promotes high-fat enhanced metastasis of LLC. PMID:25356654

  9. Achieving high-resolution soft-tissue imaging with cone-beam CT: a two-pronged approach for modulation of x-ray fluence and detector gain

    NASA Astrophysics Data System (ADS)

    Graham, S. A.; Siewerdsen, J. H.; Moseley, D. J.; Keller, H.; Shkumat, N. A.; Jaffray, D. A.

    2005-04-01

    Cone-beam computed tomography (CBCT) presents a highly promising and challenging advanced application of flat-panel detectors (FPDs). The great advantage of this adaptable technology is in the potential for sub-mm 3D spatial resolution in combination with soft-tissue detectability. While the former is achieved naturally by CBCT systems incorporating modern FPD designs (e.g., 200 - 400 um pixel pitch), the latter presents a significant challenge due to limitations in FPD dynamic range, large field of view, and elevated levels of x-ray scatter in typical CBCT configurations. We are investigating a two-pronged strategy to maximizing soft-tissue detectability in CBCT: 1) front-end solutions, including novel beam modulation designs (viz., spatially varying compensators) that alleviate detector dynamic range requirements, reduce x-ray scatter, and better distribute imaging dose in a manner suited to soft-tissue visualization throughout the field of view; and 2) back-end solutions, including implementation of an advanced FPD design (Varian PaxScan 4030CB) that features dual-gain and dynamic gain switching that effectively extends detector dynamic range to 18 bits. These strategies are explored quantitatively on CBCT imaging platforms developed in our laboratory, including a dedicated CBCT bench and a mobile isocentric C-arm (Siemens PowerMobil). Pre-clinical evaluation of improved soft-tissue visibility was carried out in phantom and patient imaging with the C-arm device. Incorporation of these strategies begin to reveal the full potential of CBCT for soft-tissue visualization, an essential step in realizing broad utility of this adaptable technology for diagnostic and image-guided procedures.

  10. Gain weighted eigenspace assignment

    NASA Technical Reports Server (NTRS)

    Davidson, John B.; Andrisani, Dominick, II

    1994-01-01

    This report presents the development of the gain weighted eigenspace assignment methodology. This provides a designer with a systematic methodology for trading off eigenvector placement versus gain magnitudes, while still maintaining desired closed-loop eigenvalue locations. This is accomplished by forming a cost function composed of a scalar measure of error between desired and achievable eigenvectors and a scalar measure of gain magnitude, determining analytical expressions for the gradients, and solving for the optimal solution by numerical iteration. For this development the scalar measure of gain magnitude is chosen to be a weighted sum of the squares of all the individual elements of the feedback gain matrix. An example is presented to demonstrate the method. In this example, solutions yielding achievable eigenvectors close to the desired eigenvectors are obtained with significant reductions in gain magnitude compared to a solution obtained using a previously developed eigenspace (eigenstructure) assignment method.

  11. Spontaneous emission of a two-level static atom coupling with the electromagnetic vacuum fluctuations outside a high-dimensional Einstein Gauss-Bonnet black hole

    E-print Network

    Ming Zhang; Zhan-Ying Yang; Rui-Hong Yue

    2014-07-04

    In present paper, by using the generalized DDC formalism, we investigate the spontaneous excitation of an static atom interacting with electromagnetic vacuum fluctuations outside a EGB black hole in $d$-dimensions. We find that spontaneous excitation does not occur in Boulware vacuum. The Gauss-Bonnet term has no effect on the stability of the atom. Finally, we discuss the contribution of the coupling constant and dimensional factor to the results in three different kinds of spacetime.

  12. Effects of olmesartan and enalapril at low or high doses on cardiac, renal and vascular interstitial matrix in spontaneously hypertensive rats.

    PubMed

    Porteri, Enzo; Rodella, Luigi; Rizzoni, Damiano; Rezzani, Rita; Paiardi, Silvia; Sleiman, Intissar; De Ciuceis, Carolina; Boari, Gianluca E M; Castellano, Maurizio; Bianchi, Rossella; Agabiti-Rosei, Enrico

    2005-01-01

    We have evaluated the effects of different doses of an angiotensin-converting enzyme (ACE) inhibitor, enalapril (ENA) and of an angiotensin II type 1 receptor blocker olmesartan (OLM), on extracellular matrix of the heart, kidney, aorta and mesenteric artery of spontaneously hypertensive rats (SHR). Forty SHR and eight Wistar-Kyoto controls (WKY) were included in the study. Eight SHR were treated with high-dose OLM 15 mg/kg per day, eight with high-dose ENA 25 mg/kg per day, eight with low-dose OLM 1 mg/kg per day and eight with low-dose ENA (2 mg/kg per day). Eight SHR and eight WKY were kept untreated as controls. Treatment was from age 4 to 12 weeks. Systolic blood pressure (SBP) was measured non-invasively every week. The left ventricular weight to body weight (RLVM) was measured, and the cardiac, aortic and glomerular interstitial collagen content was evaluated using Sirius red staining and image analysis. Mesenteric small arteries were dissected and mounted on a micromyograph, and the media:lumen ratio (M/L) was calculated. Collagen subtypes were evaluated by polarized light microscopy. The SHR treated with high-dose OLM or ENA showed a normalization of SBP. The RLVM was significantly increased in untreated SHR compared with untreated WKY, whereas significantly lower values were observed in the groups of SHR treated with high-dose OLM or ENA. A significant increase in cardiac and glomerular collagen content was observed in untreated SHR. Both high- or low-dose OLM and ENA normalized collagen content in the heart and the kidney. Both high-dose OLM and high-dose ENA normalized M/L ratio; however, OLM proved to be more effective than ENA in normalizing collagen pattern. In fact, aortic collagen content was normalized by both high-dose and low-dose OLM, but only by high-dose ENA. In conclusion, both OLM and ENA were significantly and equally effective in the prevention of cardiac and renal damage in SHR, whereas OLM was more effective than ENA in terms of effects on vascular extracellular matrix. PMID:16036499

  13. The effect of a county's public high school summer remediation program on student gains on end-of-course standard of learning tests in Algebra I, Biology, Chemistry, Geometry and World History and Geography II

    NASA Astrophysics Data System (ADS)

    Aiken, Brenda L.

    The Commonwealth of Virginia requires high school students to receive a passing grade in core courses and a passing score on End-of-Course Standards of Learning (EOC SOL) tests to receive verified credits that lead to a Virginia high school diploma. These tests are believed to accurately reflect what students should know and be able to do in order to experience success in their endeavors beyond high school. For some students remediation is required to experience success on EOC SOL tests. This study sought to determine the effect of a County's public high school summer remediation program on student gains on EOC SOL tests in Algebra I, Biology, Chemistry, Geometry, and World History and Geography II. Specifically, the purpose of the study sought to determine the following: (a) If significant gains were made by students who attended the summer remediation program; (b) If significant gains were made by students who did not attend the summer remediation program; (c) If there were differences in gain scores of students who attended and those who did not attend the summer remediation program; and (d) If there were differences in gain scores among students who attended the summer remediation program related to school site, gender, ethnicity, learning ability group, socioeconomic status, and level of English proficiency. The results of the study indicate that students who attended and those who did not attend the summer remediation program made significant gains. However, the gains for students who attended the summer remediation program were significantly greater than the gains made by students who did not attend. The study also found that there were no significant differences in gain scores among students who attended the summer remediation program related to gender, ethnicity, learning ability group, socioeconomic status, and level of English proficiency. There were significant differences in Algebra I gain scores related to school site. Recommendations for practitioners and further research are presented. The study contributes to research on standards-based summer remediation programs and their effect on student gains on high-stakes tests.

  14. Antihypertensive Effect of Radix Paeoniae Alba in Spontaneously Hypertensive Rats and Excessive Alcohol Intake and High Fat Diet Induced Hypertensive Rats

    PubMed Central

    Su-Hong, Chen; Qi, Chen; Bo, Li; Jian-Li, Gao; Jie, Su; Gui-Yuan, Lv

    2015-01-01

    Radix Paeoniae Alba (Baishao, RPA) has long been used in traditional Chinese medicine formulation to treat hypertension by repression the hyperfunction of liver. However, whether the RPA itself has the antihypertensive effect or not is seldom studied. This study was to evaluate the protective effect of RPA on hypertensive rats. Alcohol in conjunction with a high fat diet- (ACHFD-) induced hypertensive rats and spontaneously hypertensive rats (SHR) was constantly received either RPA extract (25 or 75?mg/kg) or captopril (15?mg/kg) all along the experiments. As a result, RPA extract (75?mg/kg) could significantly reduce systolic blood pressure of both ACHFD-induced hypertensive rats and SHR after 9-week or 4-week treatment. In ACHFD-induced hypertensive rats, the blood pressure was significantly increased and the lipid profiles in serum including triglyceride, total cholesterol, LDL-cholesterol, and HDL-cholesterol were significantly deteriorated. Also, hepatic damage was manifested by a significant increase in alanine transaminase (ALT) and aspartate transaminase (AST) in serum. The RPA extract significantly reversed these parameters, which revealed that it could alleviate the liver damage of rats. In SHR, our result suggested that the antihypertensive active of RPA extract may be related to its effect on regulating serum nitric oxide (NO) and endothelin (ET) levels. PMID:25784949

  15. A Combination of Cytokines Rescues Highly Purified Leukemic CLL B-Cells from Spontaneous Apoptosis In Vitro

    PubMed Central

    Ghamlouch, Hussein; Ouled-Haddou, Hakim; Damaj, Gandhi; Royer, Bruno

    2013-01-01

    B-chronic lymphocytic leukemia (B-CLL), the most common human leukemia, is characterized by predominantly non-dividing malignant mature CD5+ B lymphocytes with an apoptosis defect. Various microenvironmental stimuli confer a growth advantage on these leukemic cells and extend their survival in vivo. Nevertheless, when cultured in vitro, CLL B-cells rapidly die from apoptosis. Certain cytokines may extend the survival capacity of CLL B-cells in vitro and individual anti-apoptotic effects of several cytokines have been reported. The potential cumulative effect of such cytokines has not been studied. We therefore investigated the effects on CLL B-cells survival in vitro of humoral factors, polyclonal lymphocyte activators and a combination of cytokines known for their anti-apoptotic effects. Purified CLL B-cells were cultured in the presence or absence of various soluble molecules and the leukemic cell response was assessed in terms of viability. Apoptotic cell death was detected by flow cytometry using annexinV and 7-amino-actinomycin. The survival of CLL B-cells in vitro was highly variable. When tested separately, cytokines (IL-2, -6, -10, -12, -15, -21, BAFF and APRIL) improved CLL B cell survival moderately; in combination, they significantly enhanced survival of these cells, even up to 7 days of culture. We also report that humoral factors from autologous serum are important for survival of these malignant cells. Our findings support the concept that the CLL microenvironment is critical and suggest that soluble factors may contribute directly to the prolonged survival of CLL B-cells. Therefore, the combination of cytokines we describe as providing strong resistance to apoptosis in vitro might be used to improve the treatment of CLL. PMID:23555960

  16. Invention and Gain Analysis.

    ERIC Educational Resources Information Center

    Weber, Robert J.; Dixon, Stacey

    1989-01-01

    Gain analysis is applied to the invention of the sewing needle as well as different sewing implements and modes of sewing. The analysis includes a two-subject experiment. To validate the generality of gain heuristics and underlying switching processes, the invention of the assembly line is also analyzed. (TJH)

  17. Nutrition During Weight Gain

    E-print Network

    , Department of Food Science and Human Nutrition, 3/09 MSU is an affirmative-action, equal-opportunity employerNutrition During Pregnancy Weight Gain: The right weight gain (not too little and not too much you are taking, such as vitamins, minerals or herbs. Nutrition during pregnancy is very important

  18. Underrepresented Minority High School and College Students Report STEM-Pipeline Sustaining Gains After Participating in the Loma Linda University Summer Health Disparities Research Program

    PubMed Central

    Salto, Lorena M.; Riggs, Matt L.; Delgado De Leon, Daisy; Casiano, Carlos A.; De Leon, Marino

    2014-01-01

    An urgent need exists for graduate and professional schools to establish evidence-based STEM (science, technology, engineering, and math) pipeline programs to increase the diversity of the biomedical workforce. An untapped yet promising pool of willing participants are capable high school students that have a strong STEM interest but may lack the skills and the guided mentoring needed to succeed in competitive STEM fields. This study evaluates and compares the impact of the Loma Linda University (LLU) Summer Health Disparities Research Program on high school (HS) and undergraduate (UG) student participants. The primary focus of our summer research experience (SRE) is to enhance the research self-efficacy of the participants by actively involving them in a research project and by providing the students with personalized mentoring and targeted career development activities, including education on health disparities. The results of our study show that our SRE influenced terminal degree intent and increased participant willingness to incorporate research into future careers for both the HS and the UG groups. The quantitative data shows that both the HS and the UG participants reported large, statistically significant gains in self-assessed research skills and research self-efficacy. Both participant groups identified the hands-on research and the mentor experience as the most valuable aspects of our SRE and reported increased science skills, increased confidence in science ability and increased motivation and affirmation to pursue a science career. The follow-up data indicates that 67% of the HS participants and 90% of the UG participants graduated from college with a STEM degree; for those who enrolled in graduate education, 61% and 43% enrolled in LLU, respectively. We conclude that structured SREs can be highly effective STEM strengthening interventions for both UG and HS students and may be a way to measurably increase institutional and biomedical workforce diversity. PMID:25250695

  19. Comparing gains and losses.

    PubMed

    McGraw, A Peter; Larsen, Jeff T; Kahneman, Daniel; Schkade, David

    2010-10-01

    Loss aversion in choice is commonly assumed to arise from the anticipation that losses have a greater effect on feelings than gains, but evidence for this assumption in research on judged feelings is mixed. We argue that loss aversion is present in judged feelings when people compare gains and losses and assess them on a common scale. But many situations in which people judge and express their feelings lack these features. When judging their feelings about an outcome, people naturally consider a context of similar outcomes for comparison (e.g., they consider losses against other losses). This process permits gains and losses to be normed separately and produces psychological scale units that may not be the same in size or meaning for gains and losses. Our experiments show loss aversion in judged feelings for tasks that encourage gain-loss comparisons, but not tasks that discourage them, particularly those using bipolar scales. PMID:20739673

  20. Rice koji reduced body weight gain, fat accumulation, and blood glucose level in high-fat diet-induced obese mice

    PubMed Central

    Yoshizaki, Yumiko; Kawasaki, Chihiro; Cheng, Kai-Chun; Ushikai, Miharu; Amitani, Haruka; Asakawa, Akihiro; Okutsu, Kayu; Sameshima, Yoshihiro; Takamine, Kazunori

    2014-01-01

    Rice koji is considered a readily accessible functional food that may have health-promoting effects. We investigated whether white, yellow, and red koji have the anti-obesity effect in C57BL/6J mice fed a high-fat diet (HFD), which is a model for obesity. Mice were fed HFD containing 10% (w/w) of rice koji powder or steamed rice for 4 weeks. Weight gain, epididymal white adipose tissue, and total adipose tissue weight were significantly lower in all rice koji groups than in the HFD-rice group after 4 weeks. Feed efficiency was significantly reduced in the yellow koji group. Blood glucose levels were significantly lower in the white and red koji groups with HOMA-R and leptin levels being reduced in the white koji group. White and red koji increased glucose uptake and GLUT4 protein expression in L6 myotube cells. These results showed that all rice koji have the anti-obesity or anti-diabetes effects although the mechanisms may differ depending on the type of rice koji consumed. PMID:25237599

  1. Effective spontaneous PT-symmetry breaking in hybridized metamaterials

    E-print Network

    Kang, Ming; Li, Jensen

    2013-01-01

    We show that metamaterials can be used as a testing ground to investigate spontaneous symmetry breaking associated with non-Hermitian quantum systems. By exploring the interplay between near-field dipolar coupling and material absorption or gain, we demonstrate various spontaneous breaking processes of the $\\mathcal{PT}$-symmetry for a series of effective Hamiltonians associated to the scattering matrix. By tuning the coupling parameter, coherent perfect absorption, laser action and gain-induced complete reflection ($\\pi$ reflector) by using an ultra-thin metamaterial can be obtained. Moreover, an ideal $\\mathcal{PT}$-symmetry can be established effectively in a passive system by using metamaterials.

  2. Effective spontaneous PT-symmetry breaking in hybridized metamaterials

    NASA Astrophysics Data System (ADS)

    Kang, Ming; Liu, Fu; Li, Jensen

    2013-05-01

    We show that metamaterials can be used as a testing ground to investigate spontaneous symmetry breaking associated with non-Hermitian quantum systems. By exploring the interplay between near-field dipolar coupling and material absorption or gain, we demonstrate various spontaneous breaking processes of the PT symmetry for a series of effective Hamiltonians associated with the scattering matrix. By tuning the coupling parameter, coherent perfect absorption, laser action, and gain-induced complete reflection (? reflector) by using an ultrathin metamaterial can be obtained. Moreover, an ideal PT symmetry can be established effectively in a passive system by exploring the balance between scattering and absorption loss using metamaterials.

  3. A high calcium diet containing nonfat dry milk reduces weight gain and associated adipose tissue inflammation in diet-induced obese mice when compared to high calcium alone

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High dietary calcium (Ca) has been reported to have anti-obesity and anti-inflammatory properties. Evidence for these properties of dietary Ca in animal models of polygenic obesity have been confounded by the inclusion of dairy food components (proteins and/or carbohydrates), thus the individual ef...

  4. A dairy-based high calcium diet improves glucose homeostasis and reduces further weight gain in high fat fed mice in the context of pre-existing obesity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: High dietary calcium (Ca) in the context of a dairy food matrix has been shown to reduce obesity development and associated inflammation in diet-induced obese (DIO) mice. However, the influence of Ca and dairy on these phenotypes in the context of pre-existing obesity is not known. Met...

  5. Spontaneous rupture of the liver in a patient with systemic AL amyloidosis undergoing treatment with high-dose melphalan and autologous stem cell transplantation: A case report with literature review

    PubMed Central

    TAM, MARTIN; SELDIN, DAVID C.; FORBES, BENJAMIN M.; CONNORS, LAWREEN H.; SKINNER, MARTHA; ORAN, BETUL; QUILLEN, KAREN; SANCHORAWALA, VAISHALI

    2010-01-01

    A 55-year-old woman with primary Immunoglobulin light chain (AL) systemic amyloidosis died due to spontaneous rupture of her liver following treatment with high-dose melphalan and autologous stem cell transplant (HDM/SCT). She was first diagnosed after developing nephrotic-range proteinuria. Spontaneous rupture of her liver occurred 10 days after treatment with HDM/SCT and was complicated by septic shock. She was not eligible for surgical intervention and died shortly after. Amyloid fibrils were extracted from the autopsied liver sample (05-135L) and the biochemical nature of the fibrils was analyzed using electrophoretic and immunohistochemical techniques. Our testing showed that the fibrils were composed of immunoglobulin lambda light chains that were not glycosylated. While the liver is often involved in AL amyloidosis, this is the first documented case of a spontaneous hepatic rupture in a patient during treatment with HDM/SCT. A literature review of spontaneous liver rupture in patients with amyloidosis is presented. PMID:20536404

  6. Spontaneous rupture of the ureter.

    PubMed

    Eken, A; Akbas, T; Arpaci, T

    2015-02-01

    Spontaneous rupture of the ureter is a very rare condition and usually results from ureteral obstruction by a calculus. Only theoretical mecha nisms 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

  7. Reduction of undulator radiation and FEL small gain due to wiggler errors

    SciTech Connect

    Friedman, A.

    1991-01-01

    A deterministic approach is taken to study the effect of errors in the wiggler magnet field on the spontaneous emission and the gain of Free Electron Lasers. A 3D formulation is used to derive the reduction in spontaneous emission due to changes in the time of flight of the electrons. A generalization of Madey's theorem to 3D is then used to calculate the reduction in the FEL small gain. 6 refs.

  8. High average power scaleable thin-disk laser

    DOEpatents

    Beach, Raymond J. (Livermore, CA); Honea, Eric C. (Sunol, CA); Bibeau, Camille (Dublin, CA); Payne, Stephen A. (Castro Valley, CA); Powell, Howard (Livermore, CA); Krupke, William F. (Pleasanton, CA); Sutton, Steven B. (Manteca, CA)

    2002-01-01

    Using a thin disk laser gain element with an undoped cap layer enables the scaling of lasers to extremely high average output power values. Ordinarily, the power scaling of such thin disk lasers is limited by the deleterious effects of amplified spontaneous emission. By using an undoped cap layer diffusion bonded to the thin disk, the onset of amplified spontaneous emission does not occur as readily as if no cap layer is used, and much larger transverse thin disks can be effectively used as laser gain elements. This invention can be used as a high average power laser for material processing applications as well as for weapon and air defense applications.

  9. Pregnancy and Weight Gain

    MedlinePLUS Videos and Cool Tools

    A service of the U.S. National Library of Medicine National Institutes of Health Home About MedlinePlus Site ... based on current recommendations from the Institute of Medicine. Nearly a third gained weight within the guidelines ...

  10. Weight gain - unintentional

    MedlinePLUS

    ... control pills Corticosteroids Some drugs used to treat bipolar disorder, schizophrenia, and depression Some drugs used to treat ... gain without a known cause Hair loss Feel cold more often than before Swollen feet and shortness ...

  11. Directive gain of circular Taylor patterns.

    NASA Technical Reports Server (NTRS)

    Rudduck, R. C.; Wu, D. C. F.; Hyneman, R. F.

    1971-01-01

    The practicality of various classes of planar aperture distributions in high-gain antenna design is discussed, and optimal circular Taylor distributions are illustrated. In particular, the directive gain of circular Taylor patterns is determined. It is shown that so-called optimum patterns - i.e., uniform sidelobes in all planes, are severly limited for planar apertures because of excessive sidelobe power. The optimum directive gain of the circular Taylor pattern with a given sidelobe level can be obtained by appropriate design.

  12. Scintillator high-gain avalanche rushing photoconductor active-matrix flat panel imager: Zero-spatial frequency x-ray imaging properties of the solid-state SHARP sensor structure

    PubMed Central

    Wronski, M.; Zhao, W.; Tanioka, K.; DeCrescenzo, G.; Rowlands, J. A.

    2012-01-01

    Purpose: The authors are investigating the feasibility of a new type of solid-state x-ray imaging sensor with programmable avalanche gain: scintillator high-gain avalanche rushing photoconductor active matrix flat panel imager (SHARP-AMFPI). The purpose of the present work is to investigate the inherent x-ray detection properties of SHARP and demonstrate its wide dynamic range through programmable gain. Methods: A distributed resistive layer (DRL) was developed to maintain stable avalanche gain operation in a solid-state HARP. The signal and noise properties of the HARP-DRL for optical photon detection were investigated as a function of avalanche gain both theoretically and experimentally, and the results were compared with HARP tube (with electron beam readout) used in previous investigations of zero spatial frequency performance of SHARP. For this new investigation, a solid-state SHARP x-ray image sensor was formed by direct optical coupling of the HARP-DRL with a structured cesium iodide (CsI) scintillator. The x-ray sensitivity of this sensor was measured as a function of avalanche gain and the results were compared with the sensitivity of HARP-DRL measured optically. The dynamic range of HARP-DRL with variable avalanche gain was investigated for the entire exposure range encountered in radiography/fluoroscopy (R/F) applications. Results: The signal from HARP-DRL as a function of electric field showed stable avalanche gain, and the noise associated with the avalanche process agrees well with theory and previous measurements from a HARP tube. This result indicates that when coupled with CsI for x-ray detection, the additional noise associated with avalanche gain in HARP-DRL is negligible. The x-ray sensitivity measurements using the SHARP sensor produced identical avalanche gain dependence on electric field as the optical measurements with HARP-DRL. Adjusting the avalanche multiplication gain in HARP-DRL enabled a very wide dynamic range which encompassed all clinically relevant medical x-ray exposures. Conclusions: This work demonstrates that the HARP-DRL sensor enables the practical implementation of a SHARP solid-state x-ray sensor capable of quantum noise limited operation throughout the entire range of clinically relevant x-ray exposures. This is an important step toward the realization of a SHARP-AMFPI x-ray flat-panel imager. PMID:23127101

  13. Scintillator high-gain avalanche rushing photoconductor active-matrix flat panel imager: Zero-spatial frequency x-ray imaging properties of the solid-state SHARP sensor structure

    SciTech Connect

    Wronski, M.; Zhao, W.; Tanioka, K.; DeCrescenzo, G.; Rowlands, J. A. [Department of Radiation Oncology, Sunnybrook Health Sciences Center, Toronto, Ontario M4N 3M5 (Canada); Department of Radiology, State University of New York at Stony Brook, Stony Brook, New York 11794-8460 (United States); Tokyo Denki University, Tokyo, 120-8551 (Japan); Thunder Bay Regional Research Institute, Thunder Bay, Ontario P7A 7T1 (Canada)

    2012-11-15

    Purpose: The authors are investigating the feasibility of a new type of solid-state x-ray imaging sensor with programmable avalanche gain: scintillator high-gain avalanche rushing photoconductor active matrix flat panel imager (SHARP-AMFPI). The purpose of the present work is to investigate the inherent x-ray detection properties of SHARP and demonstrate its wide dynamic range through programmable gain. Methods: A distributed resistive layer (DRL) was developed to maintain stable avalanche gain operation in a solid-state HARP. The signal and noise properties of the HARP-DRL for optical photon detection were investigated as a function of avalanche gain both theoretically and experimentally, and the results were compared with HARP tube (with electron beam readout) used in previous investigations of zero spatial frequency performance of SHARP. For this new investigation, a solid-state SHARP x-ray image sensor was formed by direct optical coupling of the HARP-DRL with a structured cesium iodide (CsI) scintillator. The x-ray sensitivity of this sensor was measured as a function of avalanche gain and the results were compared with the sensitivity of HARP-DRL measured optically. The dynamic range of HARP-DRL with variable avalanche gain was investigated for the entire exposure range encountered in radiography/fluoroscopy (R/F) applications. Results: The signal from HARP-DRL as a function of electric field showed stable avalanche gain, and the noise associated with the avalanche process agrees well with theory and previous measurements from a HARP tube. This result indicates that when coupled with CsI for x-ray detection, the additional noise associated with avalanche gain in HARP-DRL is negligible. The x-ray sensitivity measurements using the SHARP sensor produced identical avalanche gain dependence on electric field as the optical measurements with HARP-DRL. Adjusting the avalanche multiplication gain in HARP-DRL enabled a very wide dynamic range which encompassed all clinically relevant medical x-ray exposures. Conclusions: This work demonstrates that the HARP-DRL sensor enables the practical implementation of a SHARP solid-state x-ray sensor capable of quantum noise limited operation throughout the entire range of clinically relevant x-ray exposures. This is an important step toward the realization of a SHARP-AMFPI x-ray flat-panel imager.

  14. Brazilian Multicentre Study on Preterm Birth (EMIP): Prevalence and Factors Associated with Spontaneous Preterm Birth

    PubMed Central

    Passini, Renato; Cecatti, Jose G.; Lajos, Giuliane J.; Tedesco, Ricardo P.; Nomura, Marcelo L.; Dias, Tabata Z.; Haddad, Samira M.; Rehder, Patricia M.; Pacagnella, Rodolfo C.; Costa, Maria L.; Sousa, Maria H.

    2014-01-01

    Background Preterm birth rate is increasing and is currently a worldwide concern. The purpose of this study was to estimate the prevalence of preterm birth in a sample of health facilities in Brazil and to identify the main risk factors associated with spontaneous preterm births. Methods and Findings This was a multicentre cross sectional study on preterm births in 20 referral obstetric hospitals with a case-control component to identify factors associated with spontaneous preterm birth. Surveillance was implemented at all centres to identify preterm births. For eligible consenting women, data were collected through a post-delivery questionnaire completed with information from all mother-newborn medical records until death or discharge or at a maximum of 60 days post-delivery, whichever came first. The risk of spontaneous preterm birth was estimated with OR and 95%CI for several predictors. A non-conditional logistic regression analysis was then performed to identify independently associated factors. The overall prevalence of preterm birth was 12.3%. Among them, 64.6% were spontaneous and 35.4% therapeutic. In the case-control component, 2,682 spontaneous preterm births were compared to a sample of 1,146 term births. Multivariate analyses identified the following as risk factors for spontaneous preterm birth among women with at least one previous birth: a previous preterm birth (ORadj?=?3.19, 2.30–4.43), multiple pregnancy (ORadj?=?29.06, 8.43–100.2), cervical insufficiency (ORadj?=?2.93, 1.07–8.05), foetal malformation (ORadj?=?2.63, 1.43–4.85), polyhydramnios (ORadj?=?2.30, 1.17–4.54), vaginal bleeding (ORadj?=?2.16, 1.50–3.11), and previous abortion (ORadj?=?1.39, 1.08–1.78). High BMI (ORadj?=?0.94, 0.91–0.97) and weight gain during gestation (ORadj?=?0.92, 0.89–0.95) were found to be protective factors. Conclusions The preterm birth rate in these health facilities in Brazil is high and spontaneous preterm births account for two thirds of them. A better understanding of the factors associated with spontaneous preterm birth is of utmost importance for planning effective measures to reduce the burden of its increasing rates. PMID:25299699

  15. The Spatial and Temporal Variability of a High-Energy Beach: Insight Gained From Over 50 High-Resolution Sub-aerial Surveys

    NASA Astrophysics Data System (ADS)

    Hansen, J. E.; Barnard, P. L.

    2008-12-01

    Since April 2004 a monitoring program of 7 km-long Ocean Beach, San Francisco, CA, has led to the completion of 55 Global Positioning System topographic surveys of the sub-aerial beach. The four-year timeseries contains over 1 million beach elevation measurements and documents detailed changes of the beach over a variety of spatial, temporal, and physical forcing scales. The goal of this ongoing data collection is to understand the variability in beach response as a function of wave forcing and offshore morphology which will ultimately aid in sediment management and erosion mitigation efforts. Several statistical methods are used to describe and account for the observed beach change, including empirical orthogonal functions (EOFs) and linear regression. Results from the EOF analysis show that the first mode, and approximately 50% of the observed variance of either the mean high water (MHW) or mean sea level (MSL) position, is explained by the seasonal movement of sediment on and offshore. The second mode, and approximately 15% of the variance, is dominated by alongshore variability, possibly corresponding to the position of cusps and embayments. Higher level modes become increasingly variable in the alongshore direction and each explain little of the observed variance. In both cases the first temporal mode is well correlated (R2~=0.7) with offshore significant wave height averaged over the previous 80 to 110 days, suggesting that seasonal wave height variations are the primary driver of intra-annual shoreline position. No other modes exhibit good correlation with offshore wave parameters regardless of the averaging time. The observed seasonal change is superimposed on a longer term trend of net annual accretion at the north end of Ocean Beach and erosion at the south end. Areas at the northern end have seen as much as 60 m of cumulative shoreline progradation since 2004, while some areas of the southern portion have retrograded nearly as much. This pattern shows an overall rotation in the shoreline position hinged on a nodal point in the middle portion of the beach. The nodal point roughly corresponds to the location where the southern lobe of a large ebb tidal delta welds to the coast, suggesting that wave conditions coupled with offshore morphologic variability is a key control on short and long-term beach evolution.

  16. A low-power high-performance configurable auto-gain control loop for a digital hearing aid SoC

    NASA Astrophysics Data System (ADS)

    Chengying, Chen; Hainan, Liu; Yong, Hei; Jun, Fan; Xiaoyu, Hu

    2013-10-01

    A low-power, configurable auto-gain control loop for a digital hearing aid system on a chip (SoC) is presented. By adopting a mixed-signal feedback control structure and peak detection and judgment, it can work in automatic gain or variable gain control modes through a digital signal processing unit. A noise-reduction and dynamic range (DR) improvement technique is also used to ensure the DR of the circuit in a low-voltage supply. The circuit is implemented in an SMIC 0.13 ?m 1P8M CMOS process. The measurement results show that in a 1 V power supply, 1.6 kHz input frequency and 200 mVp—p, the SFDR is 74.3 dB, the THD is 66.1 dB, and the total power is 89 ?W, meeting the application requirements of hearing aid SoCs.

  17. Colloquium: Spontaneous magnon decays

    NASA Astrophysics Data System (ADS)

    Zhitomirsky, M. E.; Chernyshev, A. L.

    2013-01-01

    A theoretical overview of the phenomenon of spontaneous magnon decays in quantum antiferromagnets is presented. The intrinsic zero-temperature damping of magnons in quantum spin systems is a fascinating many-body effect, which has recently attracted significant attention in view of its possible observation in neutron-scattering experiments. An introduction to the theory of magnon interactions and a discussion of necessary symmetry and kinematic conditions for spontaneous decays are provided. Various parallels with the decays of anharmonic phonons and excitations in superfluid He4 are extensively used. Three principal cases of spontaneous magnon decays are considered: field-induced decays in Heisenberg antiferromagnets, zero-field decays in spiral antiferromagnets, and triplon decays in quantum-disordered magnets. Analytical results are compared with available numerical data and prospective materials for experimental observation of the decay-related effects are briefly discussed.

  18. Biomodal spontaneous fission

    SciTech Connect

    Hulet, E.K. (Lawrence Livermore National Lab., CA (USA))

    1989-09-26

    Investigations of mass and kinetic-energy distributions from spontaneous fission have been extended in recent years to an isotope of element 104 and, for half-lives, to an isotope of element 108. The results have been surprising in that spontaneous fission half-lives have turned out to be much longer than expected and mass and kinetic- energy distributions were found to abruptly shift away from those of the lighter actinides, showing two modes of fission. These new developments have caused a re-evaluation of our understanding of the fission process, bringing an even deeper appreciation of the role played by nuclear shell effects upon spontaneous fission properties. 16 refs., 10 figs.

  19. Microchannel plate modal gain variations with temperature

    NASA Technical Reports Server (NTRS)

    Slater, David C.; Timothy, J. G.

    1993-01-01

    Measurements of the modal gain of two high-gain curved-channel microchannel plates (MCPs) at various operating temperatures are presented. Both MCPs were fabricated from the Long Life glass with 12-micron diam channels on 15-micron centers. The modal gain was found to decrease with increasing temperature at a rate of -0.1 percent C. This reduction of gain with temperature is attributed primarily to an axial temperature gradient along each MCP channel creating a nonuniform electric field within the channel that lowers the effective output gain. A lowering of the secondary electron yield resulting from increased phonon scattering of secondary electrons released within the walls of the MCP channels was assessed, but was found to have a negligible contribution to the drop in gain with temperature.

  20. Current Feedback Loop Gain Analysis and

    E-print Network

    Lanterman, Aaron

    presents a high imped- ance to the input voltage, V+ , so as to not load the driving source. Any voltage voltage to follow the non-inverting input voltage while also providing a low impedance path for an error-couple the signal gain from the loop gain part of the overall transfer function. Commonly available voltage feedback

  1. Spontaneous vesicle recycling in the synaptic bouton

    PubMed Central

    Truckenbrodt, Sven; Rizzoli, Silvio O.

    2014-01-01

    The trigger for synaptic vesicle exocytosis is Ca2+, which enters the synaptic bouton following action potential stimulation. However, spontaneous release of neurotransmitter also occurs in the absence of stimulation in virtually all synaptic boutons. It has long been thought that this represents exocytosis driven by fluctuations in local Ca2+ levels. The vesicles responding to these fluctuations are thought to be the same ones that release upon stimulation, albeit potentially triggered by different Ca2+ sensors. This view has been challenged by several recent works, which have suggested that spontaneous release is driven by a separate pool of synaptic vesicles. Numerous articles appeared during the last few years in support of each of these hypotheses, and it has been challenging to bring them into accord. We speculate here on the origins of this controversy, and propose a solution that is related to developmental effects. Constitutive membrane traffic, needed for the biogenesis of vesicles and synapses, is responsible for high levels of spontaneous membrane fusion in young neurons, probably independent of Ca2+. The vesicles releasing spontaneously in such neurons are not related to other synaptic vesicle pools and may represent constitutively releasing vesicles (CRVs) rather than bona fide synaptic vesicles. In mature neurons, constitutive traffic is much dampened, and the few remaining spontaneous release events probably represent bona fide spontaneously releasing synaptic vesicles (SRSVs) responding to Ca2+ fluctuations, along with a handful of CRVs that participate in synaptic vesicle turnover. PMID:25538561

  2. Amplified spontaneous emission in solar-pumped iodine laser

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  3. Proton maser gain

    SciTech Connect

    Ensley, D.L.

    1989-02-01

    It is shown that in the low beam space-charge limit the small-signal gain for a proton maser, calculated from a dispersion relation, is proportional to (..omega../sub p//..omega../sub 0/)/sup 2/, and agrees to this order with that derived from orbital velocity perturbations, to order (qE/sub x//m..omega../sub 0/U/sub 0/)/sup 2/. The rf current density in the interaction space is derived; ''self-bunching'' and the underlying physics of the gain (''self-catching'') are explored and a comparison is made between the collective formulation and that of single-particle orbits.

  4. Spontaneous Lorentz Violation and Baryogenesis

    E-print Network

    Jing Shu

    2007-12-18

    In the presence of background fields that spontaneously violate Lorentz invariance, a matter-antimatter asymmetry can be generated even in thermal equilibrium. In this paper we systematically investigate models of this type, showing that either high-energy or electroweak versions of baryogenesis are possible, depending on the dynamics of the Lorentz-violating fields. We identify two scenarios of interest: baryogenesis from a weak-scale pseudo-Nambu-Goldstone boson with intermediate-scale baryon-number violation, and sphaleron-induced baryogenesis driven by a constant-magnitude vector with a late-time phase transition.

  5. Spontaneous Lorentz violation and baryogenesis.

    SciTech Connect

    Shu, J.; High Energy Physics; Univ. of Chicago

    2008-03-01

    In the presence of background fields that spontaneously violate Lorentz invariance, a matter-antimatter asymmetry can be generated even in thermal equilibrium. In this paper we systematically investigate models of this type, showing that either high-energy or electroweak versions of baryogenesis are possible, depending on the dynamics of the Lorentz-violating fields. We identify two scenarios of interest: baryogenesis from a weak-scale pseudo-Nambu-Goldstone boson with intermediate-scale baryon-number violation, and sphaleron-induced baryogenesis driven by a constant-magnitude vector with a late-time phase transition.

  6. Radion Induced Spontaneous Baryogenesis

    E-print Network

    G. L. Alberghi; R. Casadio; A. Tronconi

    2007-01-09

    We describe a possible scenario for the baryogenesis arising when matter is added on the branes of a Randall-Sundrum model with a radion stabilizing potential. We show that the radion field can naturally induce spontaneous baryogenesis when the cosmological evolution for the matter on the branes is taken into account.

  7. Management by Spontaneity.

    ERIC Educational Resources Information Center

    Olson, Richard M.; Thomas, M. Donald

    1999-01-01

    Management by spontaneity shuns job descriptions, supervisory duties, needs assessment, strategic planning, group process, and problem solving. Not for the fainthearted, MBS requires knowledge of psychology, lawyerly skills, and philosophic wisdom. MBS remains untested, as current job descriptions have confined authors to MBO and TQM. (MLH)

  8. Spontaneous intracranial hypotension.

    PubMed Central

    Renowden, S A; Gregory, R; Hyman, N; Hilton-Jones, D

    1995-01-01

    The clinical features and radiological appearances of spontaneous intracranial hypotension are described in three patients and the medical literature is reviewed. Awareness of this condition and its differentiation from more sinister meningitic processes is important to avoid unnecessary invasive investigations and to allow prompt diagnosis and effective treatment. Images PMID:8530936

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  10. A low-noise, and high-gain double-balanced mixer for 77 GHz automotive radar front-ends in SiGe bipolar technology

    Microsoft Academic Search

    W. Perndl; H. Knapp; M. Wurzer; K. Aufinger; T. F. Meister; T. F. Bock; W. Simburger; A. L. Scholtz

    2004-01-01

    An active down-conversion mixer for automotive radar applications at 76 GHz to 81 GHz was realized in a 200 GHz fT SiGe bipolar technology. A conversion gain of more than 24 dB and a single-sideband noise figure of less than 14 dB is achieved. The 1 dB output compression point is -4 dBm. The power consumption is 300 mW at

  11. Design of a high-gain laser diode-array pumped Nd:YAG Alternating Precessive Slab Amplifier (APS-Amplifier)

    NASA Technical Reports Server (NTRS)

    Coyle, D. Barry

    1991-01-01

    In the design of space qualifiable laser systems for ranging and altimetry, such as NASA's Geodynamic Laser Ranging System (GLRS), the transmitter must be kept small, powerful yet efficient, and must consist of as few components as possible. A novel preamplifier design is examined which requires no external beam steering optics, yielding a compact component with simple alignment procedures. The gains achieved are comparable to multipass zigzag amplifiers using two or more sets of external optics for extra passes through the amplifying medium.

  12. Gain and Phase-margin measurements

    NASA Technical Reports Server (NTRS)

    Pierce, B. D.

    1977-01-01

    Simple battery-powered test circuit will contribute negligible error when taking open-loop measurements of gain and phase parameters. This is especially helpful when measuring high-grain circuits containing integrators.

  13. Beyond secondary gain.

    PubMed

    van Egmond, J J

    2005-06-01

    Research suggests that a conscious desire for external illness gain can have internal unconscious effects, in that subjective symptoms can be heightened by external reward. This mechanism can be explained on the basis of Freud's later work, in which he mentions two types of resistance, which resemble each other--the need to be punished and the need to be ill. The concept of the need to be ill can explain why in modern society, with its established systems of support, regulations, and procedures that are conducive to illness behavior, patients who consciously strive for external gain can experience strengthening feelings of being ill and even deterioration without being aware of this process. PMID:15959674

  14. Spontaneous Quantum Hall Liquids

    NASA Astrophysics Data System (ADS)

    Zhang, Fan

    2012-02-01

    Driven by electron-electron interactions, bilayer graphene and its thicker cousins, chirally (ABC) stacked multilayers, exhibit a variety of distinct broken symmetry states in which each spin-valley flavor spontaneously transfers charge between layers, because of their flat touching bands and large pseudospin chiralities. These gapped states are accompanied by large momentum space Berry curvatures and different types of topological orders. These competing ground states are distinguished by their flavor Hall conductivities, orbital magnetizations, edge state properties, and response to external fields. These spontaneous quantum Hall (SQH) states at zero field smoothly evolve into quantum Hall ferromagnet states at finite field. Various phase transitions occur by tuning carrier densities, temperature, and external fields. Recently, SQH states have started to be observed and explored in transport and Hall experiments on suspended devices with dual gates.

  15. Spontaneous intracranial hypotension

    Microsoft Academic Search

    Bahram Mokri

    2001-01-01

    Spontaneous intracranial hypotension (SIH) is typically manifested by orthostatic headaches that may be associated with one\\u000a or more of several other symptoms, including pain or stiffness of the neck, nausea, emesis, horizontal diplopia, dizziness,\\u000a change in hearing, visual blurring or visual field cuts, photophobia, interscapular pain, and occasionally face numbness or\\u000a weakness or radicular upper-limb symptoms. Cerebrospinal fluid (CSF) pressures,

  16. Gain control mechanisms in spinal motoneurons

    PubMed Central

    Johnson, Michael D.; Heckman, Charles J.

    2014-01-01

    Motoneurons provide the only conduit for motor commands to reach muscles. For many years, motoneurons were in fact considered to be little more than passive “wires”. Systematic studies in the past 25 years however have clearly demonstrated that the intrinsic electrical properties of motoneurons are under strong neuromodulatory control via multiple sources. The discovery of potent neuromodulation from the brainstem and its ability to change the gain of motoneurons shows that the “passive” view of the motor output stage is no longer tenable. A mechanism for gain control at the motor output stage makes good functional sense considering our capability of generating an enormous range of forces, from very delicate (e.g., putting in a contact lens) to highly forceful (emergency reactions). Just as sensory systems need gain control to deal with a wide dynamic range of inputs, so to might motor output need gain control to deal with the wide dynamic range of the normal movement repertoire. Two problems emerge from the potential use of the brainstem monoaminergic projection to motoneurons for gain control. First, the projection is highly diffuse anatomically, so that independent control of the gains of different motor pools is not feasible. In fact, the system is so diffuse that gain for all the motor pools in a limb likely increases in concert. Second, if there is a system that increases gain, probably a system to reduce gain is also needed. In this review, we summarize recent studies that show local inhibitory circuits within the spinal cord, especially reciprocal and recurrent inhibition, have the potential to solve both of these problems as well as constitute another source of gain modulation. PMID:25120435

  17. Quantifying the mechanisms of domain gain in animal proteins

    E-print Network

    Buljan, Marija; Frankish, Adam; Bateman, Alex

    2010-07-15

    innovation. However, the relative contributions of the different molecular mechanisms that underlie domain gains in animals are still unknown. By using animal gene phylogenies we were able to identify a set of high confidence domain gain events and by looking...

  18. Models of baryogenesis via spontaneous Lorentz violation

    SciTech Connect

    Carroll, Sean M.; Shu Jing [Enrico Fermi Institute, Deptartment of Physics, Chicago, Illinois (United States) and Kavli Institute for Cosmological Physics University of Chicago, 5640 S. Ellis Avenue Chicago, Illinois 60637 (United States)

    2006-05-15

    In the presence of background fields that spontaneously violate Lorentz invariance, a matter-antimatter asymmetry can be generated even in thermal equilibrium. In this paper we systematically investigate models of this type, showing that either high-energy or electroweak versions of baryogenesis are possible, depending on the dynamics of the Lorentz-violating fields. In addition to the previously studied models of spontaneous baryogenesis and quintessential baryogenesis, we identify two scenarios of interest: baryogenesis from a weak-scale pseudo-Nambu-Goldstone boson with intermediate-scale baryon-number violation, and sphaleron-induced baryogenesis driven by a constant-magnitude vector with a late-time phase transition.

  19. Spontaneous emission through heavy photon bands

    NASA Astrophysics Data System (ADS)

    Yannopapas, Vassilios

    2004-07-01

    We examine the spontaneous emission spectrum of a Lgr-type three-level atom embedded in a coupled-resonator optical waveguide. Owing to the high degree of confinement of light within the resonators, the waveguide modes can be obtained in the framework of an electromagnetic tight-binding theory. The corresponding density of modes exhibits singularities at the band edges leading to interesting features in the spontaneous emission spectrum such as dark lines and narrow emission peaks. The position and the shape of these features depend strongly on the geometry and refractive index of the waveguide.

  20. High-speed and low-dark-current flip-chip InAlAs\\/InAlGaAs quaternary well superlattice APDs with 120 GHz gain-bandwidth product

    Microsoft Academic Search

    I. Watanabe; S. Sugou; H. Ishikawa; T. Anan; K. Makita; M. Tsuji; K. Taguchi

    1993-01-01

    High-speed flip-chip InAlAs\\/InAlGaAs quaternary well superlattice avalanche photodiodes grown by gas-source molecular beam epitaxy have been achieved with 120-GHz gain-bandwidth product. These photodiodes exhibit a maximum bandwidth of 15 GHz, 0.34-?A dark current at a multiplication factor of 20, a capacitance of 0.17 pF, 65% quantum efficiency, and a low breakdown voltage of about 20 V. A clear eye opening

  1. Spontaneous recovery in dynamical networks

    NASA Astrophysics Data System (ADS)

    Majdandzic, Antonio; Podobnik, Boris; Buldyrev, Sergey V.; Kenett, Dror Y.; Havlin, Shlomo; Eugene Stanley, H.

    2014-01-01

    Much research has been carried out to explore the structural properties and vulnerability of complex networks. Of particular interest are abrupt dynamic events that cause networks to irreversibly fail. However, in many real-world phenomena, such as brain seizures in neuroscience or sudden market crashes in finance, after an inactive period of time a significant part of the damaged network is capable of spontaneously becoming active again. The process often occurs repeatedly. To model this marked network recovery, we examine the effect of local node recoveries and stochastic contiguous spreading, and find that they can lead to the spontaneous emergence of macroscopic `phase-flipping' phenomena. As the network is of finite size and is stochastic, the fraction of active nodes z switches back and forth between the two network collective modes characterized by high network activity and low network activity. Furthermore, the system exhibits a strong hysteresis behaviour analogous to phase transitions near a critical point. We present real-world network data exhibiting phase switching behaviour in accord with the predictions of the model.

  2. Spontaneous stochasticity of velocity in turbulence models

    E-print Network

    Mailybaev, Alexei A

    2015-01-01

    We analyze the phenomenon of spontaneous stochasticity in fluid dynamics formulated as the nonuniqueness of solutions resulting from viscosity at infinitesimal scales acting through intermediate on large scales of the flow. We study the finite-time onset of spontaneous stochasticity in a real version of the GOY shell model of turbulence. This model allows high-accuracy numerical simulations for a wide range of scales (up to ten orders of magnitude) and demonstrates non-chaotic dynamics, but leads to an infinite number of solutions in the vanishing viscosity limit after the blowup time. Thus, the spontaneous stochasticity phenomenon is clearly distinguished from the chaotic behavior in turbulent flows. We provide the numerical and theoretical description of the system dynamics at all stages. This includes the asymptotic analysis before and after the blowup leading to universal (periodic and quasi-periodic) renormalized solutions, followed by nonunique stationary states at large times.

  3. Quantum theory of magnetic bremsstrahlung gain

    NASA Astrophysics Data System (ADS)

    Deck, Robert T.; Gill, Peter G.

    1982-07-01

    We present a quantum electrodynamic calculation of the gain associated with the stimulated emission and absorption of photons by high-energy electrons in the presence of a spatially periodic, static magnetic field. The calculation is relevant to the description of a high-energy electron laser in the long-interaction-length low-density (single-particle) regime. The different kinematic constraints imposed on the photon-emission and -absorption processes are shown to produce the effect of population inversion in an energetic electron beam which allows for a net gain in the number of photons produced per unit path length. The spectral dependence of the gain on the wave vector of the emitted photon has a width determined by the incident electron momentum distribution and a maximum in the vicinity of a k value [2(W10mc2)2 (2??0)] determined by the central electron momentum W10c and the spatial period of the magnetic field. Derived formulas for the gain and gain-minus-loss coefficients are compared with formulas obtained on the basis of the stimulated Comptonscattering model. While the separate gain and loss coefficients diverge in the limit ?-->0, the gain-minus-loss coefficient is shown to have a finite value in this limit which agrees with the result of a classical derivation.

  4. Assess the key physics that underpins high-hydro coupling-efficiency in NDCX-II experiments and high-gain heavy ion direct drive target designs using proven hydro codes like HYDRA

    SciTech Connect

    Barnard, J. J.; Hay, M. J.; Logan, B. G.; Ng, S. F.; Perkins, L. J.; Veitzer, S.; Yu, S. S.

    2010-07-01

    The simulations provided in this milestone have solidified the theoretical underpinning of direct drive targets and also the ability to design experiments on NDCX II that will enhance our understanding of ion-beam hydrodynamic coupling, and thus be relevant to IFE. For the case of the IFE targets, we have studied hydro and implosion efficiency using HYDRA in ID, a starting point towards the goal of polar direct drive in geometry compatible with liquid wall chambers. Recent analysis of direct drive fusion energy targets using heavy ion beams has found high coupling efficiency of ion beam energy into implosion energy. However, to obtain optimal coupling, the ion energy must increase during the pulse in order to penetrate the outflowing ablated material, and deposit the energy close enough to the fuel so that the fuel achieves sufficient implosion velocity. We have computationally explored ID (radial) time dependent models of ion driven direct drive capsule implosions using the Arbitrary Lagrangian-Eulerian (ALE) code HYDRA, to help validate the theoretical analysis done so far, particularly exploring the effects of varying the ion energy and ion current over the course of the pulse. On NDCX II, experiments have been proposed to explore issues of ion penetration of the outflowing plasma over the course of the ion pulse. One possibility is to create a first pulse of ions that heats a planar target, and produces an outflow of material. A second pulse, {approx}10 ns after the first, of higher ion energy (and hence larger projected range) will interact with this outflow before reaching and further heating the target. We have investigated whether the change in range can be tailored to match the evolution of the ablation front. We have carried out simulations using the one-dimensional hydrodynamic code DISH and HYDRA to set parameters for this class of experiments. DISH was upgraded with an ion deposition algorithm, and we have carried out ID (planar) simulations. HYDRA was also used for ID (planar) and 2D (r,z) simulations of potential experiments. We have also explored whether similar physics could be studied using an energy ramp (i.e., a velocity tilt) rather than two separate pulses. We have shown that an optimum occurs in the macropulse duration (with fixed velocity tilt) that maximizes the shock strength. In the area of IFE target design we have continued to explore direct drive targets composed of deuterium-tritium fuel and ablator layers. We have extended our previous target designs at 0.44 MJ drive energy, gain 50, (50 MeV foot, 500 MeV main pulse, Rb ion, which requires a large number of beams due to a high beam space charge constraint) to a power plant scale 3.7 MJ drive energy, gain {approx}150 (220 MeV foot, 2.2 GeV main pulse, Hg ion) that eases requirements on the accelerator. We have studied the effects of two important design choices on ICF target performance. We have shown that increasing the number of foot pulses may reduce the target's in-flight adiabat and consequently improve its compressibility and fusion yield. As in the case of laser drive, the first three shocks are the most important to the target's performance, with additional shocks contributing only marginally to compression and burn. We have also demonstrated that ion range lengthening during the main pulse can further reduce the target adiabat and improve the efficiency with which beam energy is coupled into the target. (Ion range lengthening using two different kinetic energies for the foot and main pulse has previously proven effective in the design of high gain targets).

  5. Idiopathic spontaneous haemoperitoneum due to a ruptured middle colic artery aneurysm

    PubMed Central

    Skouras, Christos; Lalountas, Miltiadis A.; Triantafyllou, Apostolos; Angelidou, Stamatia; Ballas, Konstantinos D.

    2011-01-01

    Introduction Idiopathic spontaneous intra-abdominal haemorrhage is a rare, but challenging condition, associated with high mortality if not managed appropriately. The preoperative diagnosis is difficult, despite the recent advances in imaging. We present the clinical manifestations of this condition, as well as the available diagnostic and therapeutic modalities. Presentation of case We report a case of a spontaneously ruptured dissecting aneurysm of the middle colic artery, which was managed with an emergency laparotomy and aneurysmatectomy. Interestingly, no evidence of vasculitis, infection or collagen disease was discovered during the histopathology examination of the specimen. Discussion The treatment of idiopathic spontaneous intra-abdominal haemorrhage revolves around patient resuscitation and management of the source of bleeding. In case of a ruptured aneurysm of the middle colic artery, the surgical management includes emergency laparotomy, arterial ligation and resection of the aneurysm. Transarterial embolisation has been suggested as a safe and less invasive alternative approach. Conclusion A ruptured middle colic artery aneurysm should be included in the differential diagnosis of any unexplained intra-abdominal haemorrhage. Aneurysmatectomy is the treatment of choice, with radiologic interventional techniques gaining ground in the management of this entity. PMID:22096715

  6. Spontaneously broken mass

    NASA Astrophysics Data System (ADS)

    Endlich, Solomon; Nicolis, Alberto; Penco, Riccardo

    2015-01-01

    The Galilei group involves mass as a central charge. We show that the associated superselection rule is incompatible with the observed phenomenology of superfluid helium 4: this is recovered only under the assumption that mass is spontaneously broken. This remark is somewhat immaterial for the real world, where the correct space-time symmetries are encoded by the Poincaré group, which has no central charge. Yet it provides an explicit example of how superselection rules can be experimentally tested. We elaborate on what conditions must be met for our ideas to be generalizable to the relativistic case of the integer/half-integer angular momentum superselection rule.

  7. Spontaneous wave packet reduction

    NASA Astrophysics Data System (ADS)

    Ghirardi, G. C.

    1994-06-01

    This article has taken into account the main conceptual difficulties met by standard quantum mechanics in dealing with physical processes involving macroscopic systems. An idea stressed has been how J. A. Wheeler's remarks and lucid analysis have been relevant in pinpointing and bringing to its extreme consequences the puzzling aspects of quantum phenomena. The recently proposed models of spontaneous dynamical reduction shown represent a consistent way to overcome the conceptual difficulties of the standard theory. Obviously, many nontrivial problems remain open, the first and more relevant one being that of generalizing the model theories considered to the relativistic case. This is the challenge of the dynamical reduction program.

  8. Initial state angular asymmetries in high energy p+A collisions: spontaneous breaking of rotational symmetry by a color electric field and C-odd fluctuations

    E-print Network

    Adrian Dumitru; Andre V. Giannini

    2014-09-15

    We present a simple model for generating initial-state azimuthal asymmetries in pA collisions from dipole scattering on an anisotropic dense target. Parity even angular harmonics arise from the C-even real part of the dipole S-matrix which spontaneously breaks rotational symmetry in two dimensions due to a condensate for the color electric field. This leads to an angular correlation with the direction of $\\vec E$. Parity odd harmonics are generated by the C-odd imaginary part (odderon) due to coupling to coherent target fluctuations which again break rotational invariance. We perform a first qualitative extraction of the amplitude and cutoff of C-odd fluctuations in the dense target.

  9. Unconventional modes in lasers with spatially varying gain and loss

    SciTech Connect

    Ge Li; Tuereci, H. E. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Chong, Y. D.; Stone, A. D. [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Rotter, S. [Institute for Theoretical Physics, Vienna University of Technology, A-1040 Vienna (Austria)

    2011-08-15

    We discuss a class of lasing modes created by a spatially inhomogeneous gain profile. These lasing modes are ''extra modes,'' in addition to, and very different from, conventional lasing modes, which arise from the passive cavity resonances. These new modes do not have high intensity across the entire gain region, but instead are localized at the gain boundary and throughout the gain-free region. They are surface modes, originating from the transmission resonances of the gain-free region. Using an S-matrix description we connect these surface modes to the lasing modes in PT-symmetric (balanced gain-loss) cavities.

  10. Controlling gain one photon at a time

    PubMed Central

    Schwartz, Gregory W; Rieke, Fred

    2013-01-01

    Adaptation is a salient property of sensory processing. All adaptational or gain control mechanisms face the challenge of obtaining a reliable estimate of the property of the input to be adapted to and obtaining this estimate sufficiently rapidly to be useful. Here, we explore how the primate retina balances the need to change gain rapidly and reliably when photons arrive rarely at individual rod photoreceptors. We find that the weakest backgrounds that decrease the gain of the retinal output signals are similar to those that increase human behavioral threshold, and identify a novel site of gain control in the retinal circuitry. Thus, surprisingly, the gain of retinal signals begins to decrease essentially as soon as background lights are detectable; under these conditions, gain control does not rely on a highly averaged estimate of the photon count, but instead signals from individual photon absorptions trigger changes in gain. DOI: http://dx.doi.org/10.7554/eLife.00467.001 PMID:23682314

  11. Fog spontaneously folds mosquito wings

    NASA Astrophysics Data System (ADS)

    Dickerson, Andrew K.; Liu, Xing; Zhu, Ting; Hu, David L.

    2015-02-01

    The flexibility of insect wings confers aerodynamic benefits, but can also present a hazard if exposed to fog or dew. Fog can cause water to accumulate on wings, bending them into tight taco shapes and rendering them useless for flight. In this combined experimental and theoretical study, we use high-speed video to film the spontaneous folding of isolated mosquito wings due to the evaporation of a water drop. We predict shapes of the deformed wing using two-dimensional elastica theory, considering both surface tension and Laplace pressure. We also recommend fold-resistant geometries for the wings of flapping micro-aerial vehicles. Our work reveals the mechanism of insect wing folding and provides a framework for further study of capillarity-driven folding in both natural and biomimetic systems at small scales.

  12. Spontaneous Pneumomediastinum with Concurrent Pneumorrhachis

    PubMed Central

    Jung, Hanna; Lee, Sang Cjeol; Lee, Deok Heon; Kim, Gun-Jik

    2014-01-01

    Spontaneous pneumomediastinum is a very uncommon entity that is defined as the presence of free air in the mediastinum without an obvious etiology. The presence of air in the spinal canal, known as concurrent pneumorrhachis, is an extremely rare epiphenomenon of spontaneous pneumomediastinum. We report a rare case of spontaneous pneumomediastinum with pneumorrhachis associated with influenza. The patient was diagnosed without invasive procedures, was managed with supportive treatment, and recovered without any complications. PMID:25551085

  13. Static and Spontaneous Electrowetting

    NASA Astrophysics Data System (ADS)

    Yeo, Leslie Y.; Chang, Hsueh-Chia

    There has been recent renewed interest in electrocapillary and electrowetting phenomena given its potential for microfluidic actuation and manipulation. Different approaches, in which a variety of electrode configurations have been adopted, however, have dominated the developments in this field. These different approaches have given rise to rich and varied behavior, which has often led to some overlap and confusion in the literature. In this article, we delineate the different observations and elucidate the relationship between these phenomena by re-stressing classical concepts and examining their limitations. Particular emphasis is placed on the distinction between static and spontaneous electrowetting. In the former, a static change in the liquid-solid macroscopic contact angle results when a dielectric film-coated planar plate electrode is employed. In the latter, a spontaneous thin fron-t-running electrowetting film is pulled out ahead of the macroscopic drop with the use of planar parallel line electrodes. This dynamically evolving electrowetting film advances much faster than the macroscopic drop itself and behaves in a self-similar manner analogous to gravity spreading films.

  14. Order in Spontaneous Behavior

    PubMed Central

    Maye, Alexander; Hsieh, Chih-hao; Sugihara, George; Brembs, Björn

    2007-01-01

    Brains are usually described as input/output systems: they transform sensory input into motor output. However, the motor output of brains (behavior) is notoriously variable, even under identical sensory conditions. The question of whether this behavioral variability merely reflects residual deviations due to extrinsic random noise in such otherwise deterministic systems or an intrinsic, adaptive indeterminacy trait is central for the basic understanding of brain function. Instead of random noise, we find a fractal order (resembling Lévy flights) in the temporal structure of spontaneous flight maneuvers in tethered Drosophila fruit flies. Lévy-like probabilistic behavior patterns are evolutionarily conserved, suggesting a general neural mechanism underlying spontaneous behavior. Drosophila can produce these patterns endogenously, without any external cues. The fly's behavior is controlled by brain circuits which operate as a nonlinear system with unstable dynamics far from equilibrium. These findings suggest that both general models of brain function and autonomous agents ought to include biologically relevant nonlinear, endogenous behavior-initiating mechanisms if they strive to realistically simulate biological brains or out-compete other agents. PMID:17505542

  15. Tertiary gain and disability syndromes.

    PubMed

    Kwan, O; Ferrari, R; Friel, J

    2001-10-01

    Since the introduction of the concept of tertiary gain by Dansak in 1973, there has been little further publication or research on this topic. Yet, tertiary gain is often the subject of debate amongst physicians, therapists, insurers, the media, and even at times the general public. Much of the controversy of disability syndromes and the health and economic burden they present has focused on secondary gain and illness behaviour. The role of tertiary gain in illness behaviour is likely also relevant, and a model of tertiary gain is needed to begin further understanding the implications of this phenomenon for patients and those who treat them. This article introduces a phraseology for tertiary gain, and models the effects of tertiary gain on illness behaviour and the interactions of secondary and tertiary gain in the setting of disability syndromes. PMID:11601869

  16. ‘Loss’ and ‘gain’ in comics

    Microsoft Academic Search

    Maria Grun; Cay Dollerup

    2003-01-01

    This article discusses translations of comics, a topic rarely dealt with in Translation Studies, with specific reference to ‘loss ‘ and ‘gain ‘. It is suggested that —for the purpose of a cogent discussion ? we may distinguish between gain with loss’ and ‘gain without loss’. Translations of comics represent a special challenge in that, in order to be successful,

  17. Gain and energy storage in holmium YLF

    NASA Technical Reports Server (NTRS)

    Storm, Mark E.; Deyst, John P.

    1991-01-01

    It is demonstrated that Q-switched holmium lasers are capable of high-gain and high-energy operation at 300 K. Small-signal gain coefficients of 0.50 and 0.12/cm have been measured in YLF and YAG, respectively. Small-signal gains of 0.50/cm are comparable to those achievable in Nd:YAG and are not typical of low-gain materials. This large gain in the Ho:YLF material is made possible by operating the amplifier in the ground state depletion mode. The amplifier performance data and associated analysis presented demonstrate that efficient energy storage is possible with very high excited state ion densities of the Ho 5I7 upper laser level. This is an important result since upconversion can limit the 5I7 population. Although upconversion was still present in this experiment, it was possible to achieve efficient energy storage, demonstrating that the problem is manageable even at high excitation densities in YLF.

  18. Spontaneous coronary artery dissection.

    PubMed

    Giacoppo, Daniele; Capodanno, Davide; Dangas, George; Tamburino, Corrado

    2014-07-15

    Spontaneous coronary artery dissection (SCAD) is a relatively rare and unexplored type of coronary disease. Although atherosclerosis, hormonal changes during pregnancy and connective tissue disorders might represent a sufficiently convincing explanation for some patients with SCAD, the many remaining cases display only a weak relationship with these causes. While on one side the clinical heterogeneity of SCAD masks a full understanding of their underlying pathophysiologic process, on the other side paucity of data and misleading presentations hamper the quick diagnosis and optimal management of this condition. A definite diagnosis of SCAD can be significantly facilitated by endovascular imaging techniques. In fact, intravascular ultrasound (IVUS) and optical coherence tomography (OCT) overcome the limitations of coronary angiography providing detailed endovascular morphologic information. In contrast, optimal treatment strategies for SCAD still represent a burning controversial question. Herein, we review the published data examining possible causes and investigating the best therapy for SCAD in different clinical scenarios. PMID:24861255

  19. Spontaneous abortion and occupation.

    PubMed

    McDonald, A D; Armstrong, B; Cherry, N M; Delorme, C; Diodati-Nolin, A; McDonald, J C; Robert, D

    1986-12-01

    Occupational factors in spontaneous abortion were studied in the current and previous pregnancies of 56,012 women interviewed in 11 Montreal maternity departments, 1982 to 1984. Ratios of observed to expected abortions (RR), after allowance for nonoccupational confounders, were significantly increased (P less than .05) among nursing assistants and attendants (RR 1.24 in current and 1.13 in previous pregnancies), food and beverage servers (RR 1.31 in current and 1.11 in previous pregnancies) and sales persons (RR 1.18 in current and 1.12 in previous pregnancies). Women whose work entailed heavy lifting, other physical effort, long hours, exposure to noise, and exposure to cold had also significantly increased risk ratios. However, when occupational groups were ranked according to work demands, thus avoiding potential bias from prior knowledge of outcome, increased risks were associated consistently only with heavy lifting and other physical effort. PMID:3806263

  20. High-dimensional immunomonitoring models of HIV-1–specific CD8 T-cell responses accurately identify subjects achieving spontaneous viral control

    PubMed Central

    Ndhlovu, Zaza M.; Chibnik, Lori B.; Proudfoot, Jacqueline; Vine, Seanna; McMullen, Ashley; Cesa, Kevin; Porichis, Filippos; Jones, R. Brad; Alvino, Donna Marie; Hart, Meghan G.; Stampouloglou, Eleni; Piechocka-Trocha, Alicja; Kadie, Carl; Pereyra, Florencia; Heckerman, David; De Jager, Philip L.; Walker, Bruce D.

    2013-01-01

    The development of immunomonitoring models to determine HIV-1 vaccine efficacy is a major challenge. Studies suggest that HIV-1–specific CD8 T cells play a critical role in subjects achieving spontaneous viral control (HIV-1 controllers) and that they will be important in immune interventions. However, no single CD8 T-cell function is uniquely associated with controller status and the heterogeneity of responses targeting different epitopes further complicates the discovery of determinants of protective immunity. In the present study, we describe immunomonitoring models integrating multiple functions of epitope-specific CD8 T cells that distinguish controllers from subjects with treated or untreated progressive infection. Models integrating higher numbers of variables and trained with the least absolute shrinkage and selection operator (LASSO) variant of logistic regression and 10-fold cross-validation produce “diagnostic tests” that display an excellent capacity to delineate subject categories. The test accuracy reaches 75% area under the receiving operating characteristic curve in cohorts matched for prevalence of protective alleles. Linear mixed-effects model analyses show that the proliferative capacity, cytokine production, and kinetics of cytokine secretion are associated with HIV-1 control. Although proliferative capacity is the strongest single discriminant, integrated modeling of different dimensions of data leverages individual associations. This strategy may have important applications in predictive model development and immune monitoring of HIV-1 vaccine trials. PMID:23233659

  1. Acting to gain information

    NASA Technical Reports Server (NTRS)

    Rosenchein, Stanley J.; Burns, J. Brian; Chapman, David; Kaelbling, Leslie P.; Kahn, Philip; Nishihara, H. Keith; Turk, Matthew

    1993-01-01

    This report is concerned with agents that act to gain information. In previous work, we developed agent models combining qualitative modeling with real-time control. That work, however, focused primarily on actions that affect physical states of the environment. The current study extends that work by explicitly considering problems of active information-gathering and by exploring specialized aspects of information-gathering in computational perception, learning, and language. In our theoretical investigations, we analyzed agents into their perceptual and action components and identified these with elements of a state-machine model of control. The mathematical properties of each was developed in isolation and interactions were then studied. We considered the complexity dimension and the uncertainty dimension and related these to intelligent-agent design issues. We also explored active information gathering in visual processing. Working within the active vision paradigm, we developed a concept of 'minimal meaningful measurements' suitable for demand-driven vision. We then developed and tested an architecture for ongoing recognition and interpretation of visual information. In the area of information gathering through learning, we explored techniques for coping with combinatorial complexity. We also explored information gathering through explicit linguistic action by considering the nature of conversational rules, coordination, and situated communication behavior.

  2. Model-based characterization of ventilatory stability using spontaneous breathing

    PubMed Central

    Edwards, Bradley A.; Sands, Scott A.; Berger, Philip J.; Wellman, Andrew; Verghese, George C.; Malhotra, Atul; Butler, James P.

    2011-01-01

    Cyclic ventilatory instabilities are widely attributed to an increase in the sensitivity or loop gain of the chemoreflex feedback loop controlling ventilation. A major limitation in the conventional characterization of this feedback loop is the need for labor-intensive methodologies. To overcome this limitation, we developed a method based on trivariate autoregressive modeling using ventilation, end-tidal Pco2 and Po2; this method provides for estimation of the overall “loop gain” of the respiratory control system and its components, chemoreflex gain and plant gain. Our method was applied to recordings of spontaneous breathing in 15 anesthetized, tracheostomized, newborn lambs before and after administration of domperidone (a dopamine D2-receptor antagonist that increases carotid body sensitivity). We quantified the known increase in hypoxic ventilatory sensitivity in response to domperidone; controller gain for O2 increased from 0.06 (0.03, 0.09) l·min?1·mmHg?1 to 0.09 (0.08, 0.13) l·min?1·mmHg?1; median (interquartile-range). We also report that domperidone increased the loop gain of the control system more than twofold [0.14 (0.12, 0.22) to 0.40 (0.15, 0.57)]. We observed no significant changes in CO2 controller gain, or plant gains for O2 and CO2. Furthermore, our estimate of the cycle duration of periodic breathing compared favorably with that observed experimentally [measured: 7.5 (7.2, 9.1) vs. predicted: 7.9 (7.0, 9.2) breaths]. Our results demonstrate that model-based analysis of spontaneous breathing can 1) characterize the dynamics of the respiratory control system, and 2) provide a simple tool for elucidating an individual's propensity for ventilatory instability, in turn allowing potential therapies to be directed at the underlying mechanisms. PMID:21474696

  3. Spontaneous rupture of the oesophagus

    Microsoft Academic Search

    S. M. Griffin; P. J. Lamb; J. Shenfine; D. L. Richardson; D. Karat; N. Hayes

    2008-01-01

    Background: The aim of this study was to evaluate the diagnosis, management and outcome of patients with spontaneous rupture of the oesophagus in a single centre. Methods: Between October 1993 and May 2007, 51 consecutive patients with spontaneous oesophageal rupture were evaluated with contrast radiology and flexible endoscopy. Patients with limited contamination who fulfilled specific criteria were managed by a

  4. Liturgical Spontaneity as Eschatological Rhetoric

    Microsoft Academic Search

    Cyprian Love

    2008-01-01

    As a result both of the influence of the Council of Trent, and of certain methodological approaches within the twentieth-century liturgical movement, the idea that Catholic liturgy might incorporate elements of spontaneous behaviour enjoyed at best a very muted acceptance before Vatican II. Moreover, despite its growth in Catholic and other Western liturgies in more recent decades, liturgical spontaneity remains

  5. Distribution of spontaneous plant hybrids

    Microsoft Academic Search

    NORMAN C. ELLSTRAND; R ICHARD WHITKUS; LOREN H. RIESEBERG

    1996-01-01

    Natural hybridization is a relatively common feature of vascular plant species and has been demonstrated to have played an important role in their evolution. Nonethe- less, it is not clear whether spontaneous hybridization occurs as a general feature of all plant families and genera or whether certain groups are especially prone to spontaneous hybrid- ization. Therefore, we inspected five modern

  6. Stimulated Raman scattering for variable gain amplification of small optically carried microwave signals

    E-print Network

    Boyer, Edmond

    to the gain of the stimulated Raman amplifier high quality variable gain amplification of optically carried microwave signals could be implemented using optimized Raman amplifiers Introduction: DistributionStimulated Raman scattering for variable gain amplification of small optically carried microwave

  7. Can LENR Energy Gains Exceed 1000?

    NASA Astrophysics Data System (ADS)

    Nagel, David J.

    2011-03-01

    Energy gain is defined as the energy realized from reactions divided by the energy required to produce those reactions. Low Energy Nuclear Reactions (LENR) have already been measured to significantly exceed the energy gain of 10 projected from ITER,possibly 15 years from now. Electrochemical experiments using the Pd-D system have shown energy gains exceeding 10. Gas phase experiments with the Ni-H system were reported to yield energy gains of over 100. Neither of these reports has been adequately verified or reproduced. However, the question in the title still deserves consideration. If, as thought by many, it is possible to trigger nuclear reactions that yield MeV energies with chemical energies of the order of eV, then the most optimistic expectation is that LENR gains could approach one million. Hence, the very tentative answer to the question above is yes. However, if LENR could be initiated with some energy cost, and then continue to "burn," very high energy gains might be realized. Consider a match and a pile of dry logs. The phenomenon termed "heat after death" will be examined to see if it might be the initial evidence for nuclear "burning."

  8. Optical gain in dye-impregnated oxidized porous silicon waveguides

    NASA Astrophysics Data System (ADS)

    Oton, C. J.; Navarro-Urrios, D.; Capuj, N. E.; Ghulinyan, M.; Pavesi, L.; González-Pérez, S.; Lahoz, F.; Martín, I. R.

    2006-07-01

    Positive optical gain under pulsed excitation in oxidized porous silicon planar waveguides impregnated with Nile blue (LC 6900) is reported. Amplified spontaneous emission measurements show a dramatic line narrowing when the pump energy is increased, together with a strong superlinear behavior. Variable stripe length measurements were performed to characterize quantitatively the amplification, and an unambiguous transition from losses to gain is observed with a threshold of ˜3mJ/cm2 at 700nm. A maximum gain coefficient of 8.7cm-1 (˜40dB/cm) is reported. Shifting excitation spot measurements confirm the reliability of our results. This system is interesting in view of an optically pumped silicon-based pulsed laser.

  9. Anomalous lasing of high-speed 850?nm InGaAlAs oxide-confined vertical-cavity surface-emitting lasers with a large negative gain-to-cavity wavelength detuning

    SciTech Connect

    Blokhin, S. A., E-mail: blokh@mail.ioffe.ru; Bobrov, M. A.; Maleev, N. A.; Sakharov, A. V.; Ustinov, V. M. [A. F. Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 26 Polytekhnicheskaya Street, Saint Petersburg 194021 (Russian Federation); Kuzmenkov, A. G. [Submicron Heterostructures for Microelectronics, Research and Engineering Center of the Russian Academy of Sciences, 26 Polytekhnicheskaya Street, Saint Petersburg 194021 (Russian Federation); A. F. Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 26 Polytekhnicheskaya Street, Saint Petersburg 194021 (Russian Federation); Blokhin, A. A. [Saint Petersburg State Polytechnical University, 29 Polytekhnicheskaya Street, Saint Petersburg 195251 (Russian Federation); Moser, P.; Lott, J. A. [Zentrum für Nanophotonik, Technische Universität Berlin, Hardenbergstrasse 36, Berlin 10623, Federal Republic of Germany (Germany); Bimberg, D. [Zentrum für Nanophotonik, Technische Universität Berlin, Hardenbergstrasse 36, Berlin 10623, Federal Republic of Germany (Germany); Electric and Computer Engineering Department, King Abdul-Aziz University, Jeddah 21589 (Saudi Arabia)

    2014-08-11

    The impact of a large negative quantum well gain-to-cavity etalon wavelength detuning on the static and dynamic characteristics of 850?nm InGaAlAs high-speed oxide-confined vertical-cavity surface-emitting lasers (VCSELs) was investigated. Three distinct lasing regimes were revealed in large square aperture (?7??m per side) devices with large detuning including: (1) an anomalous lasing via higher order Hermite–Gaussian modes at low forward bias current; (2) lasing via the lowest order Hermite–Gaussian modes at high bias current; and (3) simultaneous lasing via both types of transverse modes at intermediate bias currents. In contrast to conventional multimode VCSELs a two-resonance modulation response was observed for the case of co-lasing via multiple transverse modes with high spectral separation. The reduction in the oxide aperture area resulted in classical lasing via the lowest order modes with a conventional single-resonance frequency response.

  10. Enhancing optical gains in Si nanocrystals via hydrogenation and cerium ion doping

    SciTech Connect

    Wang, Dong-Chen; Li, Yan-Li; Song, Sheng-Chi; Guo, Wen-Ping; Lu, Ming, E-mail: minglu55@fudan.edu.cn [Department of Optical Science and Engineering, and Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Fudan University, Shanghai 200433 (China); Chen, Jia-Rong [Department of Optical Science and Engineering, and Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Fudan University, Shanghai 200433 (China); School of Information Engineering, Guizhou Minzu University, Guiyang 550025 (China)

    2014-07-28

    We report optical gain enhancements in Si nanocrystals (Si-NCs) via hydrogenation and Ce{sup 3+} ion doping. Variable stripe length technique was used to obtain gains. At 0.3?W/cm{sup 2} pumping power density of pulsed laser, net gains were observed together with gain enhancements after hydrogenation and/or Ce{sup 3+} ion doping; gains after loss corrections were between 89.52 and 341.95?cm{sup ?1}; and the photoluminescence (PL) lifetime was found to decrease with the increasing gain enhancement. At 0.04?W/cm{sup 2} power density, however, no net gain was found and the PL lifetime increased with the increasing PL enhancement. The results were discussed according to stimulated and spontaneous excitation and de-excitation mechanisms of Si-NCs.

  11. Do gains in test scores explain labor market outcomes?

    Microsoft Academic Search

    Heather Rose

    2006-01-01

    Using data from the National Education Longitudinal Study of 1988, this article investigates whether students who made relatively large test score gains during high school had larger earnings 7 years after high school compared to students whose scores improved little. In models that control for pre-high school test scores, family background, and demographic characteristics, employed women who gain one standard

  12. Spontaneous and stimulated emission from quasifree electrons

    NASA Astrophysics Data System (ADS)

    Friedman, A.; Gover, A.; Kurizki, G.; Ruschin, S.; Yariv, A.

    1988-04-01

    This article presents a unified formulation and review of an extensive class of radiation effects and devices based on free or quasifree electrons. The effects and devices reviewed include slow-wave radiators [such as ?erenkov, Smith-Purcell, and TWT (traveling-wave tube) effects and devices], periodic bremsstrahlung radiators [such as undulator radiation, magnetic bremsstrahlung FEL's (free-electron lasers), and coherent bremsstrahlung in the crystal lattice], and transverse-binding radiators [such as the CRM (cyclotron resonance maser) and channeling radiation]. Starting from a general quantum-electrodynamic model, both quantum and classical effects and operating regimes of these radiation devices are described. The article provides a unified physical description of the interaction kinematics, and presents equations for the characterization of spontaneous and stimulated radiative emission in these various effects and devices. Universal relations between the spontaneous and stimulated emission parameters are revealed and shown to be related (in the quantum limit) to Einstein relations for atomic radiators and (in the classical limit) to the relations derived by Madey for magnetic bremsstrahlung FEL for on-axis radiative emission. Examples for the application of the formulation are given, estimating the feasibility of channeling radiation x-ray laser and optical regime Smith-Purcell FEL, and deriving the gain equations of magnetic bremsstrahlung FEL and CRM for arbitrary electron propagation direction, structure (wiggler) axis, and radiative emission angle.

  13. A 4Watt X-band compact coplanar high power amplifier MMIC with 18dB gain and 25-% PAE

    Microsoft Academic Search

    A. Bessemoulin; M. R. Quay; S. Ramberger; M. Schlechtweg

    2002-01-01

    The performance of a compact coplanar (CPW) microwave monolithic integrated circuit (MMIC) amplifier with high output power in the X-band is presented. Based on our 0.3-?m gate length GaAs power PHEMT process on 4\\

  14. Lower weight gain and hepatic lipid content in hamsters fed high fat diets supplemented with white rice protein, brown rice protein, and soy protein and their hydrolysates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The physiological effects of the hydrolysates from white rice, brown rice, and soy isolate were compared to the original protein source. White rice, brown rice, and soy protein were hydrolyzed with the food grade enzyme, alcalase2.4 L®. Male Syrian hamsters were fed high-fat diets containing eithe...

  15. Gaining Access Unique Opportunities

    E-print Network

    Oak Ridge National Laboratory

    structures of proteins, nucleic acids, and their higher-order complexes. CSMB tools will help researchers that drive it. The High Flux Isotope Reactor is the highest flux reactor-based source of neutrons

  16. Multiphase Tertiary erosion history and elevation gain of the High Plains of New Mexico and Texas: A signal of widespread mid-Tertiary lithospheric modification?

    NASA Astrophysics Data System (ADS)

    Landman, R.; Flowers, R. M.; Kelley, S.

    2013-12-01

    The undeformed High Plains of North America are located over 1,000 km east of the nearest plate boundary but reach elevations of >2 km at their boundary with the southern Rocky Mountains. East of the mountain front elevations decrease gradually, but remain as high as 1 km in northern Texas. Despite the accumulation of extensive geological and geophysical datasets, there is no consensus on the mechanisms that caused high elevations in the region or on how these mechanisms may be linked to the history of deformation and volcanism in the neighboring Rocky Mountains. The timing of unroofing and uplift is key to differentiating between these mechanisms, but this too remains debated. A 350 km-long integrated apatite fission-track (AFT) and (U-Th)/He (AHe) east-west transect from the southern Rocky Mountains of New Mexico across the High Plains into northern Texas provides insight into the spatial and temporal variability of unroofing across this region during Cenozoic time. The southern Sangre de Cristo Range separates the High Plains of northern New Mexico from the Rio Grande Rift. At the western edge of the southern Sangre de Cristo Range, AFT and AHe data from Precambrian basement samples show an age-elevation relationship and indicate cooling and rapid unroofing through the shallow crust during the early Tertiary Laramide orogeny. At the eastern edge of the range, both AFT and AHe data record a late Tertiary cooling episode as young as mid-Miocene. Samples from Triassic sandstones on the High Plains 50 km east of the mountain front yield mid-Tertiary AFT and late Tertiary AHe dates. These data require post-depositional heating of samples to above ~110 °C, followed by at least 1.5 km of relatively rapid unroofing on the western High Plains between 17 Ma and the initiation of Ogallala Group deposition at ~12 Ma. This interval of unroofing predates the <10 Ma volcanism along the nearby Jemez lineament. The easternmost samples in the Texas Panhandle suggest that a smaller degree of post-depositional heating caused minimal annealing of fission tracks and partial resetting of the AHe system prior to cooling and unroofing during the mid-Tertiary. Together these results indicate that multiphase Tertiary cooling and unroofing on the High Plains took place over a wide region that stretches as far as 300 km east of the rugged Cordilleran front. This implies Tertiary lithospheric modification over the same spatial extent as the cause, due either to volcanism associated with the mid-Tertiary ignimbrite flareup or to the initiation of the Rio Grande Rift system. The results may therefore constrain the development of the low-velocity mantle that contributes to high elevations throughout the Rocky Mountain-High Plains region.

  17. Property evaluation on the spontaneous polarity for nanopowders.

    PubMed

    Meng, Junping; Liang, Jinsheng; Ding, Yan; Han, Yilin; Yuan, Youde

    2011-11-01

    For the tourmaline fine powders, in view of their low polarized charge density and easily occurred neutralization, a new evaluation model on the spontaneous polarity was proposed. By adjusting the temperature and applying electric field, the polarized charge could be measured. On this basis, a portable evaluation device was designed and assembled into four parts: Voltage Input Unit, Temperature Control Unit, Sample Loading Unit, and Charge Detection Unit. Using the designed device, the property evaluation on the spontaneous polarity of tourmaline fine powders was carried out. The spontaneous polarization intensity was finally achieved. After experimental verification, the method had the characteristics of easy operation and high accuracy. PMID:22413324

  18. Spontaneous breaking of supersymmetry

    SciTech Connect

    Zumino, B.

    1981-12-01

    There has been recently a revival of interest in supersymmetric gauge theories, stimulated by the hope that supersymmetry might help in clarifying some of the questions which remain unanswered in the so called Grand Unified Theories and in particular the gauge hierarchy problem. In a Grand Unified Theory one has two widely different mass scales: the unification mass M approx. = 10/sup 15/GeV at which the unification group (e.g. SU(5)) breaks down to SU(3) x SU(2) x U(1) and the mass ..mu.. approx. = 100 GeV at which SU(2) x U(1) is broken down to the U(1) of electromagnetism. There is at present no theoretical understanding of the extreme smallness of the ratio ..mu../M of these two numbers. This is the gauge hierarchy problem. This lecture attempts to review the various mechanisms for spontaneous supersymmetry breaking in gauge theories. Most of the discussions are concerned with the tree approximation, but what is presently known about radiative correction is also reviewed.

  19. Spontaneous coronary artery dissection.

    PubMed

    Alfonso, Fernando; Bastante, Teresa; Rivero, Fernando; Cuesta, Javier; Benedicto, Amparo; Saw, Jacqueline; Gulati, Rajiv

    2014-01-01

    Spontaneous coronary artery dissection (SCAD) is a rare but challenging clinical entity of unknown etiology. From a pathophysiological standpoint, SCAD may occur in patients with a coronary intimal tear (presenting with the classic angiographic "flap" and multiple lumens), but also in patients without an intimal rupture (presenting as an intramural hematoma). Until now, available information on SCAD was largely based on multiple, small case-series studies but, recently, data from relatively large registries have cast a new light on this disease. Classically, SCAD was thought to present in young females without traditional atherosclerotic risk factors but recent reports suggest a broader clinical spectrum encompassing older patients with associated coronary artery disease. In this review, we concentrate on 3 main aspects of this unique disease: (1) the value of intracoronary diagnostic techniques (intravascular ultrasound and optical coherence tomography) to complement coronary angiography and to provide novel diagnostic insights on this elusive clinical condition; (2) the growing clinical evidence suggesting an association and potential causation between fibromuscular dysplasia and SCAD; and (3) the challenges of coronary revascularization in this adverse anatomic setting, together with recent data suggesting that a initial, conservative medical management may be preferable for the majority of patients with SCAD. PMID:25131524

  20. Wideband and high-gain frequency stabilization of a 100-W injection-locked Nd:YAG laser for second-generation gravitational wave detectors

    Microsoft Academic Search

    Noriaki Ohmae; Shigenori Moriwaki; Norikatsu Mio

    2010-01-01

    Second-generation gravitational wave detectors require a highly stable laser with an output power greater than 100 W to attain their target sensitivity. We have developed a frequency stabilization system for a 100-W injection-locked Nd:YAG (yttrium aluminum garnet) laser. By placing an external wideband electro-optic modulator used as a fast-frequency actuator in the optical path of the slave output, we can

  1. Gains in QTL detection using an ultra-high density SNP map based on population sequencing relative to traditional RFLP/SSR markers.

    PubMed

    Yu, Huihui; Xie, Weibo; Wang, Jia; Xing, Yongzhong; Xu, Caiguo; Li, Xianghua; Xiao, Jinghua; Zhang, Qifa

    2011-01-01

    Huge efforts have been invested in the last two decades to dissect the genetic bases of complex traits including yields of many crop plants, through quantitative trait locus (QTL) analyses. However, almost all the studies were based on linkage maps constructed using low-throughput molecular markers, e.g. restriction fragment length polymorphisms (RFLPs) and simple sequence repeats (SSRs), thus are mostly of low density and not able to provide precise and complete information about the numbers and locations of the genes or QTLs controlling the traits. In this study, we constructed an ultra-high density genetic map based on high quality single nucleotide polymorphisms (SNPs) from low-coverage sequences of a recombinant inbred line (RIL) population of rice, generated using new sequencing technology. The quality of the map was assessed by validating the positions of several cloned genes including GS3 and GW5/qSW5, two major QTLs for grain length and grain width respectively, and OsC1, a qualitative trait locus for pigmentation. In all the cases the loci could be precisely resolved to the bins where the genes are located, indicating high quality and accuracy of the map. The SNP map was used to perform QTL analysis for yield and three yield-component traits, number of tillers per plant, number of grains per panicle and grain weight, using data from field trials conducted over years, in comparison to QTL mapping based on RFLPs/SSRs. The SNP map detected more QTLs especially for grain weight, with precise map locations, demonstrating advantages in detecting power and resolution relative to the RFLP/SSR map. Thus this study provided an example for ultra-high density map construction using sequencing technology. Moreover, the results obtained are helpful for understanding the genetic bases of the yield traits and for fine mapping and cloning of QTLs. PMID:21390234

  2. Smoking cessation and weight gain.

    PubMed

    Filozof, C; Fernández Pinilla, M C; Fernández-Cruz, A

    2004-05-01

    Cigarette smoking is the single most important preventable cause of death and illness. Smoking cessation is associated with substantial health benefits. Weight gain is cited as a primary reason for not trying to quit smoking. There is a great variability in the amount of weight gain but younger ages, lower socio-economic status and heavier smoking are predictors of higher weight gain. Weight change after smoking cessation appears to be influenced by underlying genetic factors. Besides, weight gain after smoking cessation is largely because of increased body fat and some studies suggest that it mostly occurs in the subcutaneous region of the body. The mechanism of weight gain includes increased energy intake, decreased resting metabolic rate, decreased physical activity and increased lipoprotein lipase activity. Although there is convincing evidence for the association between smoking cessation and weight gain, the molecular mechanisms underlying this relationship are not well understood. This review summarizes current information of the effects of nicotine on peptides involved in feeding behaviour. Smoking was shown to impair glucose tolerance and insulin sensitivity and cross-sectional studies have demonstrated that smokers are insulin-resistant and hyperinsulinaemic, as compared with non-smokers. Smoking cessation seems to improve insulin sensitivity in spite of the weight gain. Nicotine replacement - in particular nicotine gum - appears to be effective in delaying post-cessation weight gain. In a group of women who failed to quit smoking because of weight gain, a dietary intervention (intermittent very-low-calorie diet) plus nicotine gum showed to both increase success rate in terms of smoking cessation and prevent weight gain. On the other hand, body weight gain at the end of treatment was significantly lower in the patients receiving bupropion or bupropion plus nicotine patch, compared with placebo. Studies with new drugs available for the treatment of obesity - sibutramine and orlistat - are warranted. PMID:15086863

  3. Gains in Teacher Quality

    ERIC Educational Resources Information Center

    Goldhaber, Dan; Walch, Joe

    2014-01-01

    The quality of the teacher workforce in the United States is of considerable concern to education stakeholders and policymakers. Numerous studies show that student academic success depends in no small part on access to high-quality teachers. Many pundits point to the fact that in the United States, teachers tend not to be drawn from the top of the…

  4. Staggered Gain for 100+ GHz Broadband Amplifiers

    Microsoft Academic Search

    Joohwa Kim; James F. Buckwalter

    2011-01-01

    A broadband amplifier is realized with cascaded stagger-tuned stages that are equalized for high bandwidth and low gain ripple. The staggered frequency response is demon- strated to improve the transimpedance limit of active circuits. The staggered response is demonstrated with a Darlington feed- back amplifier and a constructive wave amplifier, which achieves low group delay. The broadband amplifier is implemented

  5. Gain and linewidth enhancement factor in InAs quantum-dot laser diodes

    Microsoft Academic Search

    T. C. Newell; D. J. Bossert; A. Stintz; B. Fuchs; K. J. Malloy; L. F. Lester

    1999-01-01

    Amplified spontaneous emission measurements are investigated below threshold in InAs quantum-dot lasers emitting at 1.22 ?m. The dot layer of the laser was grown in a strained quantum well (QW) on a GaAs substrate. Ground state gain is determined from cavity mode Fabry-Perot modulation. As the injection current increases, the gain rises super-linearly while changes in the index of refraction

  6. Computer algorithm for coding gain

    NASA Technical Reports Server (NTRS)

    Dodd, E. E.

    1974-01-01

    Development of a computer algorithm for coding gain for use in an automated communications link design system. Using an empirical formula which defines coding gain as used in space communications engineering, an algorithm is constructed on the basis of available performance data for nonsystematic convolutional encoding with soft-decision (eight-level) Viterbi decoding.

  7. Spontaneous resolution of subfoveal perfluorocarbon

    PubMed Central

    Oellers, Patrick; Charkoudian, Leon D; Hahn, Paul

    2015-01-01

    Perfluorocarbon liquids (PFCL) have transformed the surgical approach to complex retinal detachments, but their use can be complicated by subretinal retention. Migration of peripherally located subretinal PFCL towards the fovea is well established, but spontaneous resolution of subfoveal PFCL without surgical evacuation or displacement has rarely been described. We present a case of a large single retained subfoveal PFCL droplet following vitrectomy with membrane peeling, inferior relaxing retinectomy, and silicone oil tamponade that demonstrated spontaneous resolution 3 weeks postoperatively, with subsequent anatomic and visual improvement. No residual subretinal PFCL was noted, and we hypothesize that the PFCL droplet spontaneously extruded through a transient hole created in the thinned retina overlying the droplet, which subsequently closed spontaneously. Further understanding of the mechanisms of PFCL migration and resolution may facilitate improved treatments for this complication.

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

    PubMed

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

    2014-05-19

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

  9. Perturbed and spontaneous regional cerebral blood flow responses to changes in blood pressure after high-level spinal cord injury: the effect of midodrine

    PubMed Central

    Phillips, Aaron A.; Krassioukov, Andrei V.; Ainslie, Philip N.

    2014-01-01

    Individuals with spinal cord injury (SCI) above the T6 spinal segment suffer from orthostatic intolerance. How cerebral blood flow (CBF) responds to orthostatic challenges in SCI is poorly understood. Furthermore, it is unclear how interventions meant to improve orthostatic tolerance in SCI influence CBF. This study aimed to examine 1) the acute regional CBF responses to rapid changes in blood pressure (BP) during orthostatic stress in individuals with SCI and able-bodied (AB) individuals; and 2) the effect of midodrine (alpha1-agonist) on orthostatic tolerance and CBF regulation in SCI. Ten individuals with SCI >T6, and 10 age- and sex-matched AB controls had beat-by-beat BP and middle and posterior cerebral artery blood velocity (MCAv, PCAv, respectively) recorded during a progressive tilt-test to quantify the acute CBF response and orthostatic tolerance. Dynamic MCAv and PCAv to BP relationships were evaluated continuously in the time domain and frequency domain (via transfer function analysis). The SCI group was tested again after administration of 10 mg midodrine to elevate BP. Coherence (i.e., linearity) was elevated in SCI between BP-MCAv and BP-PCAv by 35% and 22%, respectively, compared with AB, whereas SCI BP-PCAv gain (i.e., magnitudinal relationship) was reduced 30% compared with AB (all P < 0.05). The acute (i.e., 0–30 s after tilt) MCAv and PCAv responses were similar between groups. In individuals with SCI, midodrine led to improved PCAv responses 30–60 s following tilt (10 ± 3% vs. 4 ± 2% decline; P < 0.05), and a 59% improvement in orthostatic tolerance (P < 0.01). The vertebrobasilar region may be particularly susceptible to hypoperfusion in SCI, leading to increased orthostatic intolerance. PMID:24436297

  10. Spontaneous mutations in Drosophila melanogaster

    Microsoft Academic Search

    U. Graf

    1972-01-01

    Investigations on the rate of spontaneous mutations in Drosophila melanogazter have been conducted for many years. As the Muller-5 or C1B method is the most suitable one for such experiments, most information is available on spontaneous sex-linked recessive lethals. Table 1 gives some of the rates which were found by different authors. All the data are taken from experiments in

  11. Models of Baryogenesis via Spontaneous Lorentz Violation

    E-print Network

    Sean M. Carroll; Jing Shu

    2005-11-30

    In the presence of background fields that spontaneously violate Lorentz invariance, a matter-antimatter asymmetry can be generated even in thermal equilibrium. In this paper we systematically investigate models of this type, showing that either high-energy or electroweak versions of baryogenesis are possible, depending on the dynamics of the Lorentz-violating fields. In addition to the previously-studied models of spontaneous baryogenesis and quintessential baryogenesis, we identify two scenarios of interest: baryogenesis from a pseudo-Nambu-Goldstone boson with weak-scale mass and intermediate-scale baryon-number violation, and sphaleron-induced baryogenesis driven by a constant-magnitude vector with a late-time phase transition.

  12. Spontaneous stress fractures of the femoral neck

    SciTech Connect

    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.

  13. SABER CIENTÍFICO E CONHECIMENTO ESPONTÂNEO: OPINIÕES DE ALUNOS DO ENSINO MÉDIO SOBRE TRANSGÊNICOS Scientific and spontaneous knowledge: High School students' opinions on transgenics

    Microsoft Academic Search

    Vanessa Daiana Pedrancini; Maria Júlia Corazza-Nunes

    This research investigates the knowledge that High School students have on transgenics and their opinions on the application and implications of this type of biotechnology. Questionnaires were given to one hundred final year High School students in three government schools in the northwestern region of the state of Paraná, Brazil. Answers were grouped according to the students' knowledge of the

  14. Pressure-gain combustion for gas turbines

    SciTech Connect

    Gemmen, R.; Richards, G.; Janus, M.

    1995-12-01

    As part of the Department of Energy`s Advanced Gas Turbine Systems Program, an investigation has been performed to evaluate {open_quotes}pressure-gain{close_quotes} combustion systems for gas turbine applications. Results from the investigation have shown that, due to the oscillatory combustion process, a pressure boost can be achieved for suitable combustor geometries. The pressure gains achieved thus far have been as high as 1 percent. It has also been shown that for some combustor designs operating under typical gas turbine conditions, NO{sub x} and CO emissions are about 30 ppmv and 8 ppmv, respectively. It is believed that with optimized designs, further improvements in both pressure gain and emissions may be possible. We have concluded that this technology remains a candidate for improving the efficiency of a gas turbine while reducing pollutant emissions.

  15. The angle mouse: target-agnostic dynamic gain adjustment based on angular deviation

    Microsoft Academic Search

    Jacob O. Wobbrock; James Fogarty; Shunichi Kimuro

    2009-01-01

    We present a novel method of dynamic C-D gain adaptation that improves target acquisition for users with motor impairments. Our method, called the Angle Mouse, adjusts the mouse C-D gain based on the deviation of angles sampled during movement. When angular deviation is low, the gain is kept high. When angular deviation is high, the gain is dropped, making the

  16. ASTER Urgent Response to the 2006 Eruption of Augustine Volcano, Alaska: Science and Decision Support Gained From Frequent High-resolution, Satellite Thermal Infrared Imaging of Volcanic Events

    NASA Astrophysics Data System (ADS)

    Wessels, R. L.; Ramsey, M. S.; Schneider, D. S.; Coombs, M.; Dehn, J.; Realmuto, V. J.

    2006-12-01

    Augustine Volcano, Alaska explosively erupted on January 11, 2006 after nearly eight months of increasing seismicity, deformation, gas emission, and small phreatic explosions. The volcano produced a total of 13 explosive eruptions during the last three weeks of January 2006. A new summit lava dome and two short, blocky lava flows grew during February and March 2006. A series of 7 daytime and 15 nighttime Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) scenes were acquired in response to this new activity. This response was facilitated by a new ASTER Urgent Request Protocol system. The ASTER data provided several significant observations as a part of a much larger suite of real-time or near-real-time data from other satellite (AVHRR, MODIS), airborne (FLIR, visual, gas), and ground-based (seismometers, radiometers) sensors used at the Alaska Volcano Observatory (AVO). ASTER is well-suited to volcanic observations because of its 15-m to 90-m spatial resolution, its ability to be scheduled and point off-nadir, and its ability to collect visible-near infrared (VNIR) to thermal infrared (TIR) data during both the day and night. Aided by the volcano's high latitude (59.4°N) ASTER was able to provide frequent repeat imaging as short as one day between scenes with an average 6-day repeat during the height of activity. These data provided a time series of high-resolution VNIR, shortwave infrared (SWIR - detects temperatures from about 200°C to > 600°C averaged over a 30-m pixel), and TIR (detects temperatures up to about 100°C averaged over a 90-m pixel) data of the volcano and its eruptive products. Frequent satellite imaging of volcanoes is necessary to record rapid changes in activity and to avoid recurring cloud cover. Of the 22 ASTER scenes acquired between October 30, 2005 and May 30, 2006, the volcano was clear to partly cloudy in 13 scenes. The most useful pre-eruption ASTER Urgent Request image was acquired on December 20. These data showed a broad area of slightly elevated TIR radiances that correlated with new snow-free areas and fumaroles at the summit. Thin cirrus cloud cover prevented quantitative TIR temperature extraction. During the night of February 1, 2006, ASTER imaged an ash-rich plume and fresh pyroclastic-flow deposits near the end of a 6-day continuous phase of the eruption. A decorrelation stretch of ASTER TIR bands 14, 13, and 11 suggests that the eruption plume was a mixture of ash and SO2. The 90-m TIR sensor was able to detect subtle surface radiance differences between the cooler distal ends of the pyroclastic-flow deposits and the warmer proximal areas. These temperature differences were controlled by both the age (hours) and thickness of the deposits. The SWIR data show a region of ~ 700 m x 300 m of hot pixels centered at the summit dome with a maximum brightness temperature of 619°C. ASTER data spanning February 22 through March 14 documented the continued growth of the summit domes and lava flows and gradual cooling of the block and ash deposits.

  17. Geotech Smart24 data acquisition system input terminated noise seismic response adjusted test : StreckeisenSTS2-low and high gain, Guralp CMG3T and Geotech GS13 seismometers.

    SciTech Connect

    Rembold, Randy Kai; Hart, Darren M.; Harris, James Mark

    2008-08-01

    Sandia National Laboratories has tested, evaluated and reported on the Geotech Smart24 data acquisition system with active Fortezza crypto card data signing and authentication in SAND2008-. One test, Input Terminated Noise, allows us to characterize the self-noise of the Smart24 system. By computing the power spectral density (PSD) of the input terminated noise time series data set and correcting for the instrument response of different seismometers, the resulting spectrum can be compared to the USGS new low noise model (NLNM) of Peterson (1996), and determine the ability of the matched system of seismometer and Smart24 to be quiet enough for any general deployment location. Four seismometer models were evaluated: the Streckeisen STS2-Low and High Gain, Guralp CMG3T and Geotech GS13 models. Each has a unique pass-band as defined by the frequency band of the instrument corrected noise spectrum that falls below the new low-noise model.

  18. Trend analysis of body weight parameters, mortality, and incidence of spontaneous tumors in Tg.rasH2 mice.

    PubMed

    Paranjpe, Madhav G; Denton, Melissa D; Vidmar, Tom; Elbekai, Reem H

    2014-01-01

    Carcinogenicity studies have been performed in conventional 2-year rodent studies for at least 3 decades, whereas the short-term carcinogenicity studies in transgenic mice, such as Tg.rasH2, have only been performed over the last decade. In the 2-year conventional rodent studies, interlinked problems, such as increasing trends in the initial body weights, increased body weight gains, high incidence of spontaneous tumors, and low survival, that complicate the interpretation of findings have been well established. However, these end points have not been evaluated in the short-term carcinogenicity studies involving the Tg.rasH2 mice. In this article, we present retrospective analysis of data obtained from control groups in 26-week carcinogenicity studies conducted in Tg.rasH2 mice since 2004. Our analysis showed statistically significant decreasing trends in initial body weights of both sexes. Although the terminal body weights did not show any significant trends, there was a statistically significant increasing trend toward body weight gains, more so in males than in females, which correlated with increasing trends in the food consumption. There were no statistically significant alterations in mortality trends. In addition, the incidence of all common spontaneous tumors remained fairly constant with no statistically significant differences in trends. PMID:25260361

  19. Edge-facet pumped, multi-aperture, thin-disk laser geometry for very high average power output scaling

    DOEpatents

    Zapata, Luis E.

    2004-12-21

    The average power output of a laser is scaled, to first order, by increasing the transverse dimension of the gain medium while increasing the thickness of an index matched light guide proportionately. Strategic facets cut at the edges of the laminated gain medium provide a method by which the pump light introduced through edges of the composite structure is trapped and passes through the gain medium repeatedly. Spontaneous emission escapes the laser volume via these facets. A multi-faceted disk geometry with grooves cut into the thickness of the gain medium is optimized to passively reject spontaneous emission generated within the laser material, which would otherwise be trapped and amplified within the high index composite disk. Such geometry allows the useful size of the laser aperture to be increased, enabling the average laser output power to be scaled.

  20. Identification of bacterial pathogens in ascitic fluids from patients with suspected spontaneous bacterial peritonitis by use of broad-range PCR (16S PCR) coupled with high-resolution melt analysis.

    PubMed

    Hardick, Justin; Won, Helen; Jeng, Kevin; Hsieh, Yu-Hsiang; Gaydos, Charlotte A; Rothman, Richard E; Yang, Samuel

    2012-07-01

    Spontaneous bacterial peritonitis (SBP) can be a severe complication occurring in patients with cirrhosis and ascites, with associated mortality often as high as 40%. Traditional diagnostics for SBP rely on culture techniques for proper diagnosis, although recent reports suggest that the presence of bacterial DNA in peritoneal fluid in patients with cirrhosis and ascites is an indicator of SBP. A previously published broad-range PCR (16S PCR) coupled with high-resolution melt analysis (HRMA) was compared with standard culture techniques for diagnosis of SBP in 106 peritoneal fluid samples from patients with suspected SBP. The sensitivity and specificity for 16S PCR for detecting eubacterial DNA compared with those of standard culture techniques were 100% (17/17) and 91.5% (85/89), respectively. Overall, HRMA concordance with species identification was 70.6% (12/17), although the 5 samples that were discordant at the species level were SBP resulting from a polymicrobial infection, and species-level identification for polymicrobial infections is outside the capability of HRMA. Both the broad-range 16S PCR and HRMA analysis provide useful diagnostic adjunctive assays for clinicians in detecting and identifying pathogens responsible for SBP. PMID:22573594

  1. Optical antenna enhanced spontaneous emission.

    PubMed

    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, Io = q?|xo|/d, feeding the antenna-enhanced spontaneous emission, where q|xo| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency. PMID:25624503

  2. Optical antenna enhanced spontaneous emission

    PubMed Central

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

    2015-01-01

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

  3. No Pain, High Gain Standardized Test Preparation.

    ERIC Educational Resources Information Center

    Duke, Nell K.; Ritchart, Ron

    1997-01-01

    There are many connections between good test taking practices and good general learning practices. This article offers strategies related to reading and math instruction and testing. It also describes how to teach students the fundamentals of standardized tests. Tips for reducing test stress are provided. (SM)

  4. The Lloyd L. Gaines Collection

    NSDL National Science Digital Library

    Born in 1911, Lloyd Lionel Gaines was one of eleven children. Gaines excelled in his studies and applied to the University of Missouri School of Law in 1936. He was denied admission solely on the grounds that Missouri's state constitution called for "separate education of the races." Gaines did not back down from this injustice, and he sought legal assistance from the NAACP. In 1938, Gaines won his case before the United States Supreme Court, but tragically Gaines disappeared at age 28 in Chicago and was never seen or heard from again. This engaging collection from the University of Missouri Law Library brings together documents related to Gaines's life, including photographs, family correspondence, materials related to his Supreme Court case, and related secondary materials. Visitors to the site can perform a simple search across all the materials, or dig in deeper by perform a citation search. Legal scholars will find the Case Materials area particularly engaging, as it includes links to the trial briefs, respondents' statements, and so on.

  5. In vivo two-photon imaging of mouse hippocampal neurons in dentate gyrus using a light source based on a high-peak power gain-switched laser diode.

    PubMed

    Kawakami, Ryosuke; Sawada, Kazuaki; Kusama, Yuta; Fang, Yi-Cheng; Kanazawa, Shinya; Kozawa, Yuichi; Sato, Shunichi; Yokoyama, Hiroyuki; Nemoto, Tomomi

    2015-03-01

    In vivo two-photon microscopy is an advantageous technique for observing the mouse brain at high resolution. In this study, we developed a two-photon microscopy method that uses a 1064-nm gain-switched laser diode-based light source with average power above 4 W, pulse width of 7.5-picosecond, repetition rate of 10-MHz, and a high-sensitivity photomultiplier tube. Using this newly developed two-photon microscope for in vivo imaging, we were able to successfully image hippocampal neurons in the dentate gyrus and obtain panoramic views of CA1 pyramidal neurons and cerebral cortex, regardless of age of the mouse. Fine dendrites in hippocampal CA1 could be imaged with a high peak-signal-to-background ratio that could not be achieved by titanium sapphire laser excitation. Finally, our system achieved multicolor imaging with neurons and blood vessels in the hippocampal region in vivo. These results indicate that our two-photon microscopy system is suitable for investigations of various neural functions, including the morphological changes undergone by neurons during physiological phenomena. PMID:25798313

  6. In vivo two-photon imaging of mouse hippocampal neurons in dentate gyrus using a light source based on a high-peak power gain-switched laser diode

    PubMed Central

    Kawakami, Ryosuke; Sawada, Kazuaki; Kusama, Yuta; Fang, Yi-Cheng; Kanazawa, Shinya; Kozawa, Yuichi; Sato, Shunichi; Yokoyama, Hiroyuki; Nemoto, Tomomi

    2015-01-01

    In vivo two-photon microscopy is an advantageous technique for observing the mouse brain at high resolution. In this study, we developed a two-photon microscopy method that uses a 1064-nm gain-switched laser diode-based light source with average power above 4 W, pulse width of 7.5-picosecond, repetition rate of 10-MHz, and a high-sensitivity photomultiplier tube. Using this newly developed two-photon microscope for in vivo imaging, we were able to successfully image hippocampal neurons in the dentate gyrus and obtain panoramic views of CA1 pyramidal neurons and cerebral cortex, regardless of age of the mouse. Fine dendrites in hippocampal CA1 could be imaged with a high peak-signal-to-background ratio that could not be achieved by titanium sapphire laser excitation. Finally, our system achieved multicolor imaging with neurons and blood vessels in the hippocampal region in vivo. These results indicate that our two-photon microscopy system is suitable for investigations of various neural functions, including the morphological changes undergone by neurons during physiological phenomena. PMID:25798313

  7. Using an expiratory resistor, arterial pulse pressure variations predict fluid responsiveness during spontaneous breathing: an experimental porcine study

    Microsoft Academic Search

    Michael K Dahl; Simon T Vistisen; Jacob Koefoed-Nielsen; Anders Larsson

    2009-01-01

    ABSTRACT: INTRODUCTION: Fluid responsiveness prediction is difficult in spontaneously breathing patients. Because the swings in intrathoracic pressure are minor during spontaneous breathing, dynamic parameters like pulse pressure variation (PPV) and systolic pressure variation (SPV) are usually small. We hypothesized that during spontaneous breathing, inspiratory and\\/or expiratory resistors could induce high arterial pressure variations at hypovolemia and low variations at normovolemia

  8. Flow Friction or Spontaneous Ignition?

    NASA Technical Reports Server (NTRS)

    Stoltzfus, Joel M.; Gallus, Timothy D.; Sparks, Kyle

    2012-01-01

    "Flow friction," a proposed ignition mechanism in oxygen systems, has proved elusive in attempts at experimental verification. In this paper, the literature regarding flow friction is reviewed and the experimental verification attempts are briefly discussed. Another ignition mechanism, a form of spontaneous combustion, is proposed as an explanation for at least some of the fire events that have been attributed to flow friction in the literature. In addition, the results of a failure analysis performed at NASA Johnson Space Center White Sands Test Facility are presented, and the observations indicate that spontaneous combustion was the most likely cause of the fire in this 2000 psig (14 MPa) oxygen-enriched system.

  9. Insight into high-reflectivity AlN/GaN Bragg reflectors with spontaneously formed (Al,Ga)N transient layers at the interfaces

    NASA Astrophysics Data System (ADS)

    Ga?evi?, Ž.; Eljarrat, A.; Peiró, F.; Calleja, E.

    2013-05-01

    This work gives a detailed insight into how the formation of (Al,Ga)N transient layers (TLs) at the interfaces of AlN/GaN Bragg reflectors modifies their structural and optical properties. While abrupt AlN/GaN interfaces are typically characterized with a network of microcracks, those with TLs are characterized with a network of nanocracks. Transmission electron microscopy reveals a strong correlation between strain and the TLs thickness, identifying thus the strain as the driving force for TLs formation. The AlN/GaN intermixing preserves the targeted stopband position (˜410 nm), whereas the peak reflectivity and the stopband width are both reduced, but still significantly high: >90% and >30 nm, respectively. To model their optical properties, a reduced refractive index contrast approximation is used, a novel method which yields an excellent agreement with the experiment.

  10. Relationships and parenthood in couples after assisted reproduction and in spontaneous primiparous couples: a prospective long-term follow-up study

    Microsoft Academic Search

    Gunilla Sydsjo; Marie Wadsby; Svante Kjellberg; Adam Sydsjo

    BACKGROUND: The aim of this study was to analyse relationships and parenthood in primiparous IVF couples and spontaneous primiparous couples. METHOD: In total, 110 consecutive IVF couples were studied. The control group was matched for women's age and selected out of the total spontaneous pregnant population in the study area. Questionnaires and semi-structured telephone interviews were used to gain information

  11. Multiple genetic switches spontaneously modulating bacterial mutability

    PubMed Central

    2010-01-01

    Background All life forms need both high genetic stability to survive as species and a degree of mutability to evolve for adaptation, but little is known about how the organisms balance the two seemingly conflicting aspects of life: genetic stability and mutability. The DNA mismatch repair (MMR) system is essential for maintaining genetic stability and defects in MMR lead to high mutability. Evolution is driven by genetic novelty, such as point mutation and lateral gene transfer, both of which require genetic mutability. However, normally a functional MMR system would strongly inhibit such genomic changes. Our previous work indicated that MMR gene allele conversion between functional and non-functional states through copy number changes of small tandem repeats could occur spontaneously via slipped-strand mis-pairing during DNA replication and therefore may play a role of genetic switches to modulate the bacterial mutability at the population level. The open question was: when the conversion from functional to defective MMR is prohibited, will bacteria still be able to evolve by accepting laterally transferred DNA or accumulating mutations? Results To prohibit allele conversion, we "locked" the MMR genes through nucleotide replacements. We then scored changes in bacterial mutability and found that Salmonella strains with MMR locked at the functional state had significantly decreased mutability. To determine the generalizability of this kind of mutability 'switching' among a wider range of bacteria, we examined the distribution of tandem repeats within MMR genes in over 100 bacterial species and found that multiple genetic switches might exist in these bacteria and may spontaneously modulate bacterial mutability during evolution. Conclusions MMR allele conversion through repeats-mediated slipped-strand mis-pairing may function as a spontaneous mechanism to switch between high genetic stability and mutability during bacterial evolution. PMID:20836863

  12. Spontaneous physical activity in a respiratory chamber is correlated to habitual physical activity

    Microsoft Academic Search

    S Snitker; PA Tataranni; E Ravussin

    2001-01-01

    OBJECTIVE: During a stay in a respiratory chamber without an exercise protocol, physical activity is limited to activities of daily living, change of posture and ‘fidgeting,’ collectively referred to as spontaneous physical activity (SPA). SPA is quite variable among individuals and is a heritable trait. A low SPA during a chamber stay is a predictor of weight gain in men.

  13. Are Consonant Intervals Music to Their Ears?: Spontaneous Acoustic Preferences in a Nonhuman Primate

    ERIC Educational Resources Information Center

    McDermott, Josh; Hauser, Marc

    2004-01-01

    Humans find some sounds more pleasing than others; such preferences may underlie our enjoyment of music. To gain insight into the evolutionary origins of these preferences, we explored whether they are present in other animals. We designed a novel method to measure the spontaneous sound preferences of cotton-top tamarins, a species that has been…

  14. Roof Coating Procedures and Their Productivity Gains

    E-print Network

    Bonaby, J.; Schaub, D.

    2006-01-01

    Roof Coating Procedures and their Productivity Gains John Bonaby and Dr. Diane Schaub, University of Florida As building envelope improvements are realized in organizations as ways to insulate businesses from high energy costs, the relative... procedures coupled with this experiment include an extensive assessment of obtainable literature and existing studies along with consultation from noted authorities in similar fields. In addition, a range of commercially available roof coatings...

  15. An end to insight? New Caledonian crows can spontaneously solve problems without planning their actions

    PubMed Central

    Taylor, Alex H.; Knaebe, Brenna; Gray, Russell D.

    2012-01-01

    Animals rarely solve problems spontaneously. Some bird species, however, can immediately find a solution to the string-pulling problem. They are able to rapidly gain access to food hung on the end of a long string by repeatedly pulling and then stepping on the string. It is currently unclear whether these spontaneous solutions are produced by insight or by a perceptual-motor feedback loop. Here, we presented New Caledonian crows and humans with a novel horizontal string-pulling task. While the humans succeeded, no individual crow showed a significant preference for the connected string, and all but one failed to gain the food even once. These results clearly show that string pulling in New Caledonian crows is generated not by insight, but by perceptual feedback. Animals can spontaneously solve problems without planning their actions. PMID:23097511

  16. Classification of spontaneous EEG signals in migraine

    NASA Astrophysics Data System (ADS)

    Bellotti, R.; De Carlo, F.; de Tommaso, M.; Lucente, M.

    2007-08-01

    We set up a classification system able to detect patients affected by migraine without aura, through the analysis of their spontaneous EEG patterns. First, the signals are characterized by means of wavelet-based features, than a supervised neural network is used to classify the multichannel data. For the feature extraction, scale-dependent and scale-independent methods are considered with a variety of wavelet functions. Both the approaches provide very high and almost comparable classification performances. A complete separation of the two groups is obtained when the data are plotted in the plane spanned by two suitable neural outputs.

  17. Toddlers' Spontaneous Attention to Number

    ERIC Educational Resources Information Center

    Baroody, Arthur J.; Li, Xia; Lai, Meng-lung

    2008-01-01

    Hannula and Lehtinen (2001, 2005) defined spontaneous focusing on numerosity (SFON) as the tendency to notice the relatively abstract attribute of number despite the presence of other attributes. According to nativists, an innate concept of one to three directs young children's attention to these "intuitive numbers" in everyday situations--even…

  18. Spontaneous Mutation Accumulation Studies in

    E-print Network

    Keightley, Peter

    Spontaneous Mutation Accumulation Studies in Evolutionary Genetics Daniel L. Halligan and Peter D of mutation effects, dominance, epistasis, genotype-environment interaction, mutation rate Abstract Mutation accumulation (MA) experiments, in which mutations are allowed to drift to fixation in inbred lines, have been

  19. Socialize spontaneously with mobile applications

    Microsoft Academic Search

    Zimu Liu; Yuan Feng; Baochun Li

    2012-01-01

    With the proliferation of mobile devices in both smartphone and tablet form factors, it is intuitive and natural for users to socially interact with their collaborators or competitors in multi-party conferencing, productivity, or gaming applications. In this paper, we make a case that such social interactions should be much more spontaneous to users in these applications. We design and implement

  20. A rare spontaneous enterocutaneous fistula

    PubMed Central

    Weledji, Elroy P.; Puepi, Marlene A.; Chichom, Alain M.

    2014-01-01

    A 70-year-old woman presented with a short history of a spontaneous enterocutaneos fistula in the left inguinal region. A laparotomy revealed a fistulizing Richter's hernia. The fistulizing small bowel segment was resected and the femoral hernia repaired from below. Although rare, a complicating Richter's hernia should be considered in the differential diagnosis of a groin fistula. PMID:25391523

  1. Primary spontaneous pneumothorax in Arabs

    Microsoft Academic Search

    M. R El Sonbaty; Zouheir I Bitar; A. A Marafie; Prem N Sharma

    2000-01-01

    No data are available on primary spontaneous pneumothorax (PSP) in Arabs. Hence we sought to determine its characteristics in Arabs of the Al-Ahmadi Governorate in Kuwait. All patients over 10 years of age with pneumothorax who were admitted to the only free general hospital serving Ahmadi area from 1985 to 1996 were reviewed retrospectively. The study included all patients' medical

  2. Student Experiments in Spontaneous Fission.

    ERIC Educational Resources Information Center

    Becchetti, F. D.; Ying, J. S.

    1981-01-01

    Advanced undergraduate experiments utilizing a commercially available, thin spontaneous fission source are described, including studies of the energy and mass distribution of the fission fragments and their energy and angular correlation. The experiments provide a useful introduction to fission, nuclear mass equations, heavy-ion physics, and…

  3. Spontaneous Number Representation in Mosquitofish

    ERIC Educational Resources Information Center

    Dadda, Marco; Piffer, Laura; Agrillo, Christian; Bisazza, Angelo

    2009-01-01

    While there is convincing evidence that preverbal human infants and non-human primates can spontaneously represent number, considerable debate surrounds the possibility that such capacity is also present in other animals. Fish show a remarkable ability to discriminate between different numbers of social companions. Previous work has demonstrated…

  4. Subduction initiation: spontaneous and induced

    Microsoft Academic Search

    Robert J. Stern

    2004-01-01

    The sinking of lithosphere at subduction zones couples Earth's exterior with its interior, spawns continental crust and powers a tectonic regime that is unique to our planet. In spite of its importance, it is unclear how subduction is initiated. Two general mechanisms are recognized: induced and spontaneous nucleation of subduction zones. Induced nucleation (INSZ) responds to continuing plate convergence following

  5. Low noise fiber laser based on gain feedback in a rare-earth doped fiber amplifier chain

    NASA Astrophysics Data System (ADS)

    Wan, Hongdan; Gong, Yue; Li, Xianqin; Chen, Jinlong; Wu, Peichun; Sun, Xiaohan

    2012-02-01

    We demonstrate a low noise fiber laser (LN-FL) based on gain feedback controlled high efficiency fiber amplifier chain (FAC) which connect with other optical devices in a circle manner. The FAC contains two cascaded fiber amplifiers with core pumped and double-clad pumped Erbium and Erbium-Ytterbium co-doped fibers. Gain saturation effect and amplified spontaneous emission noise in the FAC is analyzed and suppressed through gain control method. Lasing mode in the LN-FL is stabilized with fiber pigtails setting in special orbits and ensuring fiber device splicing loss low without any filters. For continuous wave operation, mode-hopping free laser spectrum with output power of 2W and SNR of 50dB is achieved. The narrowest bandwidths are about 0.2nm and 0.01nm for lasing cavity without and with filters, respectively. Lasing wavelength can be tuned in a wavelength span of 7nm by adjusting of a fiber pigtailed polarization controller. Pulsed operation of the laser under different pump seeds injection is experimental investigated and analyzed.

  6. TEMPLATING SPONTANEOUS MOLECULAR CHAIN GROWTH WITH FEEDBACK-CONTROLLED LITHOGRAPHY

    E-print Network

    Shull, Kenneth R.

    with conventional silicon microelectronic technology. This figure is an atomic resolution ultra-high vacuum scanning on silicon surfaces using ultra-high vacuum scanning tunneling microscopy. Although FCL enables unsurpassed by combining FCL with a spontaneous molecular chain growth process. In particular, FCL is used to pattern

  7. Welfare Gains from Financial Liberalization

    PubMed Central

    Townsend, Robert M.; Ueda, Kenichi

    2010-01-01

    Financial liberalization has been a controversial issue, as empirical evidence for growth enhancing effects is mixed. Here, we find sizable welfare gains from liberalization (cost to repression), though the gain in economic growth is ambiguous. We take the view that financial liberalization is a government policy that alters the path of financial deepening, while financial deepening is endogenously chosen by agents given a policy and occurs in transition towards a distant steady state. This history-dependent view necessitates the use of simulation analysis based on a growth model. Our application is a specific episode: Thailand from 1976 to 1996. PMID:20806055

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

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

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

  9. Investigation of spontaneous Brillouin scattering generation based on non-adiabatic microfibres

    NASA Astrophysics Data System (ADS)

    Zarei, A.; Jasim, A. A.; Harun, S. W.; Ahmad, H.

    2014-12-01

    Brillouin Stokes and anti-Stokes generation is successfully demonstrated in backward direction using a non-adiabatic microfibre as the gain medium. The Stokes light wavelength is up-shifted by 0.088?nm (10?GHz) from the BP wavelength as monitored by using an optical spectrum analyzer. The Brillouin scattering can also be enhanced by employing a microfibre based inline Mach–Zehnder interferometer (IMZI) as the gain medium due to its stronger multimode interference effect. It is shown that the microfibre geometry plays an important role in the spontaneous Brillouin scattering generation and gain bandwidth broadening due to its effect on irritation of the acoustic modes inside the microfibre.

  10. Comparison of experimental and theoretical gain-current relations in GaInP quantum well lasers

    SciTech Connect

    Smowton, P.M.; Chow, W.W.; Blood, P.

    2000-01-10

    The authors compare the results of a microscopic laser theory with gain and recombination currents obtained from experimental spontaneous emission spectra. The calculated absorption spectrum is first matched to that measured on a laser, ensuring that the quasi-Fermi levels for the calculation and the experiment (spontaneous emission and gain) are directly related. This allows one to determine the inhomogeneous broadening in their experimental samples. The only other inputs to the theory are literature values of the bulk material parameter. The authors then estimate the non-radiative recombination current associated with the well and wave-guide core from a comparison of measured and calculated recombination currents.

  11. HF overtone performance and residual fundamental gain

    NASA Astrophysics Data System (ADS)

    Sentman, L. H.; Carroll, D. L.; Theodoropoulos, P. T.; Waldo, R. E.

    1991-06-01

    The overtone performance of a supersonic CW HF laser was optimized by the same set of flow rates that optimized the fundamental performance. When the absorption/scattering losses of the mirrors were taken into account, an overtone efficiency of 75 to 90 percent was achieved. Overtone performance was twice as sensitive to cavity pressure as fundamental performance. There was no significant change in overtone power and efficiency as the mode volume (mirror radii of curvature) increased. However, there were an increase in the number of lasing lines and a shift to higher J lines. The overtone efficiency decreased as the mirror reflectivity decreased. The residual fundamental gains for lines P1(4-9) and P2(4-9) were measured while the laser was operating on the overtone lines P20(7-10). The low J (4-6) fundamental gains were suppressed 50 to 82 percent and the high J (7-9) fundamental gains were suppressed 15 to 42 percent. For both low and high J lines, the maximum suppression occurred near the center of the overtone beam.

  12. Spontaneity of Communication in Individuals with Autism

    Microsoft Academic Search

    Hsu-Min Chiang; Mark Carter

    2008-01-01

    This article provides an examination of issues related to spontaneity of communication in children with autism. Deficits relating\\u000a to spontaneity or initiation are frequently reported in individuals with autism, particularly in relation to communication\\u000a and social behavior. Nevertheless, spontaneity is not necessarily clearly conceptualized or measured. Several approaches to\\u000a conceptualization of communicative spontaneity are examined with a particular focus on

  13. Galileo Mission Planning Low Gain Antenna Operations

    E-print Network

    Jet Propulsion Laboratory; R. Gershman; K. L. Buxbaum; B. G. Paczkowski

    The Galileo mission operations concept is undergoing substantial redesign, necessitated by the deployment failure of the High Gain Antenna, while the spacecraft is on its way to Jupiter. The new design applies state-of-the-art technology and processes to increase the telemetry rate available through the Low Gain Antenna and to increase the information density of the telemetry. This paper describes the mission planning process being developed as part of this redesign. Principal topics include a brief description of the new mission concept and anticipated science return (these have been covered more extensively in earlier papers), identification of key drivers on the mission planning process, a description of the process and its implementation schedule, a discussion of the application of automated mission planning tools to the process, and a status report on mission planning work to date. Galileo enhancements include extensive reprogramming of on-board computers and substantial ware ...

  14. High Resolution LC-MSn Fragmentation Pattern of Palytoxin as Template to Gain New Insights into Ovatoxin-a Structure. The Key Role of Calcium in MS Behavior of Palytoxins

    NASA Astrophysics Data System (ADS)

    Ciminiello, Patrizia; Dell'Aversano, Carmela; Dello Iacovo, Emma; Fattorusso, Ernesto; Forino, Martino; Grauso, Laura; Tartaglione, Luciana

    2012-05-01

    Palytoxin is a potent marine toxin and one of the most complex natural compounds ever described. A number of compounds identified as palytoxin congeners (e.g., ovatoxins, mascarenotoxins, ostreocins, etc.) have not been yet structurally elucidated due to lack of pure material in quantities sufficient to an NMR-based structural investigation. In this study, the complex fragmentation pattern of palytoxin in its positive high resolution liquid chromatography tandem mass spectra (HR LC-MSn) was interpreted. Under the used conditions, the molecule underwent fragmentation at many sites of its backbone, and a large number of diagnostic fragment ions were identified. The natural product itself was used with no need for derivatization. Interestingly, most of the fragments contained calcium in their elemental formula. Evidence for palytoxin tendency to form adduct ions with calcium and other divalent cations in its mass spectra was obtained. Fragmentation pattern of palytoxin was used as template to gain detailed structural information on ovatoxin-a, the main toxin produced by Ostreopsis ovata, (observe correct font) a benthic dinoflagellate that currently represents the major harmful algal bloom threat in the Mediterranean area. Either the regions or the specific sites where ovatoxin-a and palytoxin structurally differ have been identified.

  15. Spontaneous order: Michael Polanyi and Friedrich Hayek

    Microsoft Academic Search

    Struan Jacobs

    2000-01-01

    This paper compares Hayek and Polanyi on spontaneous social order. Although Hayek is widely believed to have first both coined the name and explicated the idea of ‘spontaneous order’, it is in fact Michael Polanyi who did so. Numerous differences emerge between the two thinkers. The characterisation of spontaneous order in Hayek, for example, involves different types of freedom to

  16. Spontaneous Prediction Error Generation in Schizophrenia

    E-print Network

    Tani, Jun

    Spontaneous Prediction Error Generation in Schizophrenia Yuichi Yamashita¤a , Jun Tani. In this study, we show that neural networks containing schizophrenia-like deficits can spontaneously generate: Yamashita Y, Tani J (2012) Spontaneous Prediction Error Generation in Schizophrenia. PLoS ONE 7(5): e37843

  17. Spontaneous Photon Emission in Cavities

    E-print Network

    Gernot Alber; Nils Trautmann

    2014-12-04

    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.

  18. Speeding up spontaneous disease extinction

    NASA Astrophysics Data System (ADS)

    Khasin, Michael

    2012-02-01

    The dynamics of epidemic in a susceptible population is affected both by the random character of interactions between the individuals and by environmental variations. As a consequence, the sizes of the population groups (infected, susceptible, etc.) fluctuate in the course of evolution of the epidemic. In a small community a rare large fluctuation in the number of infected can result in extinction of the disease. We suggest a novel paradigm of controlling the epidemic, where the control field, such as vaccination, is designed to maximize the rate of spontaneous disease extinction. We show that, for a limited-scope vaccination, the optimal vaccination protocol and its impact on the epidemics have universal features: (i) the vaccine must be applied in pulses, (ii) the spontaneous disease extinction is synchronized with the vaccination. We trace this universality to general properties of the response of large fluctuations to external perturbations.

  19. Give spontaneity and self-discovery a chance in ASD: spontaneous peripheral limb variability as a proxy to evoke centrally driven intentional acts

    PubMed Central

    Torres, Elizabeth B.; Yanovich, Polina; Metaxas, Dimitris N.

    2013-01-01

    Autism can be conceived as an adaptive biological response to an early unexpected developmental change. Under such conceptualization one could think of emerging biological compensatory mechanisms with unique manifestations in each individual. Within a large group of affected people this would result in a highly heterogeneous spectral disorder where it would be difficult to tap into the hidden potentials of any given individual. A pressing question is how to treat the disorder while harnessing the capabilities and predispositions that the individual has already developed. It would indeed be ideal to use such strengths to accelerate the learning of self-sufficiency and independence, important as the person transitions into adulthood. In this report, we introduce a new concept for therapeutic interventions and basic research in autism. We use visuo-spatial and auditory stimuli to help augment the physical reality of the child and sensory-substitute corrupted kinesthetic information quantified in his/her movement patterns to help the person develop volitional control over the hand motions. We develop a co-adaptive child-computer interface that closes the sensory-motor feedback loops by alerting the child of a cause-effect relationship between the statistics of his/her real-time hand movement patterns and those of external media states. By co-adapting the statistics of the media states and those of the child's real-time hand movements, we found that without any food/token reward the children naturally remained engaged in the task. Even in the absence of practice, the learning gains were retained, transferred and improved 2–4 weeks later. This new concept demonstrates that individuals with autism do have spontaneous sensory-motor adaptive capabilities. When led to their self-discovery, these patterns of spontaneous behavioral variability (SBV) morph into more predictive and reliable intentional actions. These can unlock and enhance exploratory behavior and autonomy in the individual with autism spectrum disorders (ASD). PMID:23898243

  20. Randoms and TOF gain revisited

    NASA Astrophysics Data System (ADS)

    Eriksson, Lars; Conti, Maurizio

    2015-02-01

    Time-of-flight (TOF) positron emission tomography (PET) typically reduces the variance in the images by a factor that is proportional to the size of the object to be scanned, and inversely proportional to the time resolution of the PET scanner. Attempts to better characterize this relationship and understand its limits have been published, showing that such gain also increases with random fraction. In this paper, new experimental and simulated data are analyzed and old results are incorporated in the study. The proportionality of TOF gain with time resolution is confirmed, the proportionality constant is measured, the effect of the randoms is validated, and the limit of the model for small objects is investigated.