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Sample records for wave cascade subject

  1. Analysis and synthesis of cascaded metasurfaces using wave matrices

    Science.gov (United States)

    Ranjbar, Amin; Grbic, Anthony

    2017-05-01

    Various matrix representations are used to analyze the propagation of electromagnetic waves through stratified (layered) media or cascaded circuit networks. These include ABCD matrices, scattering matrices, impedance matrices, and hybrid matrices. A less known network representation is the wave matrix. In this paper, a brief review of wave matrices is presented and their relation to other network representations derived. Wave matrices are found for common interfaces such as boundaries between dielectric media, dielectric slabs, as well as electric, magnetic, and magneto-electric sheet boundaries (generalized sheet transition conditions). These results are then used to develop an analytical synthesis approach for cascaded metasurfaces: metasurfaces consisting of a cascade of sheets separated by dielectric spacers. This is in contrast to earlier works which relied on numerical solvers or optimization methods to design such structures. A few design examples are presented to demonstrate the utility of the synthesis approach.

  2. Continuous wave room temperature external ring cavity quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Revin, D. G., E-mail: d.revin@sheffield.ac.uk; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W. [Physics and Astronomy Department, The University of Sheffield, S3 7RH Sheffield (United Kingdom); Hempler, N.; Maker, G. T.; Malcolm, G. P. A. [M Squared Lasers Ltd., G20 0SP Glasgow (United Kingdom)

    2015-06-29

    An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm{sup −1} is realized by the incorporation of a diffraction grating into the cavity.

  3. Excitation and diagnosis of cascading Langmuir waves in ionospheric plasmas at Gakona, Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Burton, L M; Cohen, J A; Pradipta, R; Labno, A; Lee, M C; Batishchev, O; Rokusek, D L [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Kuo, S P [Polytechnic University, Brooklyn, NY 11201 (United States); Watkins, B J; Oyama, S [University of Alaska Fairbanks, Fairbanks, AK 99775 (United States)], E-mail: mclee@mit.edu

    2008-12-15

    Ionospheric plasma heating experiments were conducted at Gakona, Alaska to investigate cascading spectra of Langmuir wave turbulence, excited by parametric instabilities diagnosed by Modular UHF Ionospheric Radar (MUIR). This work is aimed at testing the recent theory of Kuo and Lee (2005 J. Geophys. Res. 110 A01309) that addresses how the cascade of Langmuir waves can distribute spatially via the resonant and non-resonant decay processes. The non-resonant cascade proceeds at the location where parametric decay instability (PDI) or oscillating two-stream instability (OTSI) is excited and severely hampered by the frequency mismatch effect. By contrast, the resonant cascade, which takes place at lower matching heights, has to overcome the propagation loss of the Langmuir pump waves in each cascade step. Our experimental results have corroborated these predictions about the generation of cascading Langmuir waves by the HAARP heater.

  4. Normal Incident Long Wave Infrared Quantum Dash Quantum Cascade Photodetector.

    Science.gov (United States)

    Wang, Feng-Jiao; Ren, Fei; Liu, Shu-Man; Zhuo, Ning; Zhai, Shen-Qiang; Liu, Jun-Qi; Liu, Feng-Qi; Wang, Zhan-Guo

    2016-12-01

    We demonstrate a quantum dash quantum cascade photodetector (QDash-QCD) by incorporating self-assembled InAs quantum dashes into the active region of a long wave infrared QCD. Sensitive photoresponse to normal incident light at 10 μm was observed, which is attributed to the intersubband (ISB) transitions in the quantum well/quantum dash (QW/QDash) hybrid absorption region and the following transfer of excited electrons on the extraction stair-like quantum levels separated by LO-phonon energy. The high density InAs quantum dashes were formed in the Stranski-Krastanow mode and stair-like levels were formed by a lattice matched InGaAs/InAlAs superlattice. A stable responsivity from 5 mA/W at 77 K to 3 mA/W at as high as 190 K was observed, which makes the QDash-QCD promising in high temperature operation.

  5. Lower Band Cascade of Whistler Waves Excited by Anisotropic Hot Electrons: One-Dimensional PIC Simulations

    Science.gov (United States)

    Chen, Huayue; Gao, Xinliang; Lu, Quanming; Ke, Yangguang; Wang, Shui

    2017-10-01

    Based on Time History of Events and Macroscale Interactions during Substorms waveform data, Gao, Lu, et al. (2016) have reported two special multiband chorus events, where upper band waves are located at harmonics of lower band waves. And they proposed a new generation mechanism to explain this multiband chorus wave, named as lower band cascade. With a 1-D particle-in-cell (PIC) simulation model, we have investigated the lower band cascade of whistler waves excited by anisotropic hot electrons. During each simulation, lower band whistler mode waves are firstly excited by the anisotropy of hot electrons. Later, upper band harmonic waves are generated through the nonlinear coupling between the electromagnetic and electrostatic components of lower band waves, which supports the scenario of lower band cascade. Moreover, the peak wave number (or frequency) of lower band waves will continuously drift to smaller values due to the decline of the anisotropy of hot electrons. While the peak wave number of upper band harmonic waves will be kept nearly unchanged, but their amplitude continues to decrease after their saturation. We further find that the magnetic amplitude of upper band harmonic waves tends to increase with the increase of the wave normal angle of lower band waves or the anisotropy of hot electrons. Besides, the amplitude ratio between upper band and lower band waves is positively correlated with the wave normal angle of lower band waves but is anticorrelated with the anisotropy of hot electrons. Our study has provided a more comprehensive understanding of the lower band cascade of whistler waves.

  6. Inverse energy cascade and emergence of large coherent vortices in turbulence driven by Faraday waves.

    Science.gov (United States)

    Francois, N; Xia, H; Punzmann, H; Shats, M

    2013-05-10

    We report the generation of large coherent vortices via inverse energy cascade in Faraday wave driven turbulence. The motion of floaters in the Faraday waves is three dimensional, but its horizontal velocity fluctuations show unexpected similarity with two-dimensional turbulence. The inverse cascade is detected by measuring frequency spectra of the Lagrangian velocity, and it is confirmed by computing the third moment of the horizontal velocity fluctuations. This is observed in deep water in a broad range of wavelengths and vertical accelerations. The results broaden the scope of recent findings on Faraday waves in thin layers [A. von Kameke et al., Phys. Rev. Lett. 107, 074502 (2011)].

  7. Perpendicular cascade of initial parallel Alfvén-cyclotron wave spectrum

    Science.gov (United States)

    Maneva, Yana; Ofman, Leon; Vinas, Adolfo; Poedts, Stefaan

    2015-04-01

    Solar wind turbulence at ion and electron scales often shows anisotropic nature throughout the heliosphere, with different power in parallel and perpendicular direction with respect to the orientation of the background magnetic field. The ratio between the power of the magnetic field fluctuations in k|| and k⊥ at the ion scales may vary with the heliospheric distance and depends on various parameters, such as the plasma compressibility, waves properties and the non-thermal plasma features, such as temperature anisotropies and relative drift speeds. In this work we perform 2.5D hybrid simulations to study the importance of relative drifts and a gradual solar wind expansion in a multi-species plasma, consisting of fluid electrons, kinetic (particle-in-cell) protons and a drifting population of kinetic He++ ions. At the beginning of the simulations we impose a turbulent spectrum of strictly parallel propagating Alfvén-cyclotron waves, co-existing with the drifting multi-species plasma. In the course of nonlinear evolution of the system we observe substantial anisotropic cascade of the magnetic field power spectra towards perpendicular wave numbers. The nature of the anisotropic turbulent cascade depends on the differential streaming between the different ion populations and is affected by the solar wind expansion. In the case of sub-Alfvénic differential streaming the perpendicular wave power is enhanced and the anisotropic cascade occurs at smaller parallel wave numbers. In the non-drifting case in addition to the perpendicular cascade there is also a prominent inverse parallel cascade towards larger scales. A direct parallel cascade is observed when relative drifts are present. Similar parallel cascade can be found in hybrid and compressible MHD studies in the context of nonlinear parametric instabilities scenario.

  8. Progress in high-power continuous-wave quantum cascade lasers [Invited].

    Science.gov (United States)

    Figueiredo, Pedro; Suttinger, Matthew; Go, Rowel; Tsvid, Eugene; Patel, C Kumar N; Lyakh, Arkadiy

    2017-11-01

    Multi-watt continuous-wave room temperature operation with efficiency exceeding 10% has been demonstrated for quantum cascade lasers essentially in the entire mid-wave and long-wave infrared spectral regions. Along with interband cascade lasers, these devices are the only room-temperature lasers that directly convert electrical power into mid- and long-infrared optical power. In this paper, we review the progress in high-power quantum cascade lasers made over the last 10 years. Specifically, an overview of the most important active region, waveguide, and thermal design techniques is presented, and various aspects of die packaging for high-power applications are discussed. Prospects of power scaling with lateral device dimensions for reaching optical power level in the range from 10 W to 20 W are also analyzed. Finally, coherent and spectral beam-combining techniques for very high-power infrared platforms are discussed.

  9. Harnessing rogue wave for supercontinuum generation in cascaded photonic crystal fiber.

    Science.gov (United States)

    Zhao, Saili; Yang, Hua; Zhao, Chujun; Xiao, Yuzhe

    2017-04-03

    Based on induced modulation instability, we present a numerical study on harnessing rogue wave for supercontinuum generation in cascaded photonic crystal fibers. By selecting optimum modulation frequency, we achieve supercontinuum with a great improvement on spectrum stability when long-pulse is used as the pump. In this case, rogue wave can be obtained in the first segmented photonic crystal fiber with one zero dispersion wavelength in a controllable manner. Numerical simulations show that spectral range and flatness can be regulated in an extensive range by cascading a photonic crystal fiber with two zero dispersion wavelengths. Some novel phenomena are observed in the second segmented photonic crystal fiber. When the second zero dispersion wavelength is close to the first one, rogue wave is directly translated into dispersion waves, which is conducive to the generation of smoother supercontinuum. When the second zero dispersion wavelength is far away from the first one, rogue wave is translated into the form of fundamental soliton steadily propagating in the vicinity of the second zero dispersion wavelength. Meanwhile, the corresponding red-shifted dispersion wave is generated when the phase matching condition is met, which is beneficial to the generation of wider supercontinuum. The results presented in this work provide a better application of optical rogue wave to generate flat and broadband supercontinuum in cascaded photonic crystal fibers.

  10. Magnetotransport in very long wave infrared quantum cascade detectors: Analyzing the current with and without illumination

    Energy Technology Data Exchange (ETDEWEB)

    Jasnot, François-Régis; Maëro, Simon; Vaulchier, Louis-Anne de; Guldner, Yves; Carosella, Francesca; Ferreira, Robson [Laboratoire Pierre Aigrain, École Normale Supérieure, CNRS (UMR 8551), Université P. et M. Curie, Université Paris Diderot, 24 rue Lhomond, 75231 Paris Cedex 05 (France); Delga, Alexandre; Doyennette, Laetitia; Berger, Vincent [Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Diderot - Paris 7, CNRS - UMR7162, Bâtiment Condorcet, 75205 Paris Cedex 13 (France); Carras, Mathieu [Alcatel-Thales 3-5 lab, Route départementale 128, 91767 Palaiseau Cedex (France)

    2013-12-04

    Current measurements of current have been performed on a very long wave infrared quantum cascade detector under magnetic field under both dark and light conditions. The analysis of dark current as a function of temperature highlights three regimes of transport. Under illumination, the model developed is in agreement with the oscillatory component of the experimental magnetophotocurrent. It allows to identify the key points controlling the electronic transport: crucial role of extraction, location of ionized impurities and scattering mechanisms involved in the structure. This work is valuable for the future conception of high-performance quantum cascade detectors in the infrared range.

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

    Science.gov (United States)

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

    2017-04-01

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

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

    Science.gov (United States)

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

    2014-05-05

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

  13. MAGNETOHYDRODYNAMIC KINK WAVES IN NONUNIFORM SOLAR FLUX TUBES: PHASE MIXING AND ENERGY CASCADE TO SMALL SCALES

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Roberto; Terradas, Jaume, E-mail: roberto.soler@uib.es [Departament de Física, Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain)

    2015-04-10

    Magnetohydrodynamic (MHD) kink waves are ubiquitously observed in the solar atmosphere. The propagation and damping of these waves may play relevant roles in the transport and dissipation of energy in the solar atmospheric medium. However, in the atmospheric plasma dissipation of transverse MHD wave energy by viscosity or resistivity needs very small spatial scales to be efficient. Here, we theoretically investigate the generation of small scales in nonuniform solar magnetic flux tubes due to phase mixing of MHD kink waves. We go beyond the usual approach based on the existence of a global quasi-mode that is damped in time due to resonant absorption. Instead, we use a modal expansion to express the MHD kink wave as a superposition of Alfvén continuum modes that are phase mixed as time evolves. The comparison of the two techniques evidences that the modal analysis is more physically transparent and describes both the damping of global kink motions and the building up of small scales due to phase mixing. In addition, we discuss that the processes of resonant absorption and phase mixing are closely linked. They represent two aspects of the same underlying physical mechanism: the energy cascade from large scales to small scales due to naturally occurring plasma and/or magnetic field inhomogeneities. This process may provide the necessary scenario for efficient dissipation of transverse MHD wave energy in the solar atmospheric plasma.

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

    Science.gov (United States)

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

    2012-08-15

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

  15. Tracer Studies In A Laboratory Beach Subjected To Waves

    Science.gov (United States)

    This work investigated the washout of dissolved nutrients from beaches due to waves by conducting tracer studies in a laboratory beach facility. The effects of waves were studied in the case where the beach was subjected to the tide, and that in which no tidal action was present...

  16. High power, low divergent, substrate emitting quantum cascade ring laser in continuous wave operation

    Directory of Open Access Journals (Sweden)

    D. H. Wu

    2017-03-01

    Full Text Available We demonstrate a surface grating coupled substrate emitting quantum cascade ring laser with high power room temperature continuous wave operation at 4.64 μm. A second order surface metal/semiconductor distributed-feedback grating is used for in-plane feedback and vertical out-coupling. A device with 400 μm radius ring cavity exhibits an output power of 202 mW in room temperature continuous wave operation. Single mode operation with a side mode suppression ratio of 25 dB is obtained along with a good linear tuning with temperature. The far field measurement exhibits a low divergent concentric ring beam pattern with a lobe separation of ∼0.34°, which indicates that the device operates in fundamental mode (n = 1.

  17. Nonlinear evolution of the plasma beat wave: Compressing the laser beat notes via electromagnetic cascading.

    Science.gov (United States)

    Kalmykov, Serguei; Shvets, Gennady

    2006-04-01

    The near-resonant beat wave excitation of an electron plasma wave (EPW) can be employed for generating the trains of few-femtosecond electromagnetic (EM) pulses in rarefied plasmas. The EPW produces a comoving index grating that induces a laser phase modulation at the difference frequency. As a result, the cascade of sidebands red and blue shifted by integer multiples of the beat frequency is generated in the laser spectrum. The bandwidth of the phase-modulated laser is proportional to the product of the plasma length, laser wavelength, and amplitude of the electron density perturbation. When the beat frequency is lower than the electron plasma frequency, the redshifted spectral components are advanced in time with respect to the blueshifted ones near the center of each laser beat note. The group velocity dispersion of plasma compresses so chirped beat notes to a few-laser-cycle duration thus creating a train of sharp EM spikes with the beat periodicity. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same, or sequentially in different plasmas. Evolution of the laser beat wave and electron density perturbations is described in time and one spatial dimension in a weakly relativistic approximation. Using the compression effect, we demonstrate that the relativistic bistability regime of the EPW excitation [G. Shvets, Phys. Rev. Lett. 93, 195004 (2004)] can be achieved with the initially subthreshold beat wave pulse.

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

    Directory of Open Access Journals (Sweden)

    Tawfig Eltaif

    2017-01-01

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

  19. Grid Connection of Wave Power Farm Using an N-Level Cascaded H-Bridge Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    Rickard Ekström

    2013-01-01

    Full Text Available An N-level cascaded H-bridge multilevel inverter is proposed for grid connection of large wave power farms. The point-absorber wave energy converters are individually rectified and used as isolated DC-sources. The variable power characteristics of the wave energy converters are discussed, and a method of mitigating this issue is demonstrated. The complete power control system is given in detail and has been experimentally verified for a single-phase setup of the 9-level inverter. Theoretical expressions of the power sharing between multilevel cells are derived and show good correspondence with the experimental results.

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

    Directory of Open Access Journals (Sweden)

    Rosa Weigand

    2015-09-01

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

  1. Design of a Novel High Power V-Band Helix-Folded Waveguide Cascaded Traveling Wave Tube Amplifier

    Directory of Open Access Journals (Sweden)

    Tianxiang Zhuge

    2015-01-01

    Full Text Available A design of a V-band Helix-Folded Waveguide (H-FWG cascaded traveling wave tube (TWT is presented. In this cascaded structure, a digitized nonlinear theory model is put forward first to simulate these two types of the tubes by common process. Then, an initial design principle is proposed, which can design these two different kinds of tubes universally. Using this principle, a high-gain helix TWT is carefully designed as a first stage amplifier followed by a FWG TWT to obtain high power. Simulations predict that a peak power of 800 W with saturated gain of 60 dB from 55 GHz to 60 GHz can be achieved.

  2. Stabilization of ODE-Schrodinger cascaded systems subject to boundary control matched disturbance

    Directory of Open Access Journals (Sweden)

    Ya-Ping Guo

    2015-09-01

    Full Text Available In this article, we consider the state feedback stabilization of ODE-Schrodinger cascaded systems with the external disturbance. We use the backstepping transformation to handle the unstable part of the ODE, then design a feedback control which is used to cope with the disturbance and stabilize the Schrodinger part. By active disturbance rejection control (ADRC approach, the disturbance is estimated by a constant high gain estimator, then the feedback control law can be designed. Next, we show that the resulting closed-loop system is practical stable, where the peaking value appears in the initial stage and the stabilized result requires that the derivative of disturbance be uniformly bounded. To avoid the peak phenomenon and to relax the restriction on the disturbance, a time varying high gain estimator is presented and asymptotical stabilization of the corresponding closed-loop system is proved. Finally, the effectiveness of the proposed control is verified by numerical simulations.

  3. High-power terahertz quantum cascade lasers with ∼0.23 W in continuous wave mode

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xuemin; Shen, Changle; Jiang, Tao; Zhan, Zhiqiang; Deng, Qinghua; Li, Weihua; Wu, Weidong, E-mail: wuweidongding@163.com [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, 621900, Sichuan (China); Yang, Ning; Chu, Weidong; Duan, Suqing [Institute of Applied Physics and Computational Mathematics, Beijing, 100088 (China)

    2016-07-15

    Terahertz quantum cascade lasers with a record output power up to ∼0.23 W in continuous wave mode were obtained. We show that the optimal 2.9-mm-long device operating at 3.11 THz has a low threshold current density of 270 A/cm{sup 2} at ∼15 K. The maximum operating temperature arrived at ∼65 K in continuous wave mode and the internal quantum efficiencies decreased from 0.53 to 0.19 for the devices with different cavity lengths. By using one convex lens with the effective focal length of 13 mm, the beam profile was collimated to be a quasi Gaussian distribution.

  4. P-wave complexity in normal subjects and computer models

    NARCIS (Netherlands)

    Potse, Mark; Lankveld, Theo A. R.; Zeemering, Stef; Dagnelie, Pieter C.; Stehouwer, Coen D. A.; Henry, Ronald M.; Linnenbank, André C.; Kuijpers, Nico H. L.; Schotten, Ulrich

    2016-01-01

    P waves reported in electrocardiology literature uniformly appear smooth. Computer simulation and signal analysis studies have shown much more complex shapes. We systematically investigated P-wave complexity in normal volunteers using high-fidelity electrocardiographic techniques without filtering.

  5. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    National Research Council Canada - National Science Library

    Wang, Liguo; Engström, Jens; Leijon, Mats; Isberg, Jan

    2016-01-01

    ...) damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four converters based on the concept developed by Uppsala University is studied...

  6. Evaluations on the R Wave in asymptomatic subjects: a preliminary ...

    African Journals Online (AJOL)

    This preliminary cross-sectional survey on the R wave of the 12-lead electrocardiogram (ECG) was undertaken to evaluate the normal R wave duration and amplitude of the young adult Nigerian from Jos; to ascertain significant correlation coefficients for R wave duration and amplitude, age and anthropometric ...

  7. Coordinated Control of Wave Energy Converters Subject to Motion Constraints

    Directory of Open Access Journals (Sweden)

    Liguo Wang

    2016-06-01

    Full Text Available In this paper, a generic coordinated control method for wave energy converters is proposed, and the constraints on motion amplitudes and the hydrodynamic interaction between converters are considered. The objective of the control problem is to maximize the energy converted from ocean waves, and this is achieved by coordinating the power take-off (PTO damping of each wave energy converter in the frequency domain in each sea state. In a case study, a wave energy farm consisting of four converters based on the concept developed by Uppsala University is studied. In the solution, motion constraints, including constraints on the amplitudes of displacement and velocity, are included. Twelve months of sea states, based on measured wave data at the Lysekil test site on the Swedish west coast, are used in the simulation to evaluate the performance of the wave energy farm using the new method. Results from the new coordinated control method and traditional control method are compared, indicating that the coordinated control of wave energy converters is an effective way to improve the energy production of wave energy farm in harmonic waves.

  8. Ultrabright GeV Photon Source via Controlled Electromagnetic Cascades in Laser-Dipole Waves

    Science.gov (United States)

    Gonoskov, A.; Bashinov, A.; Bastrakov, S.; Efimenko, E.; Ilderton, A.; Kim, A.; Marklund, M.; Meyerov, I.; Muraviev, A.; Sergeev, A.

    2017-10-01

    Electromagnetic cascades have the potential to act as a high-energy photon source of unprecedented brightness. Such a source would offer new experimental possibilities in fundamental science, but in the cascade process radiation reaction and rapid electron-positron plasma production seemingly restrict the efficient production of photons to sub-GeV energies. Here, we show how to overcome these energetic restrictions and how to create a directed GeV photon source, with unique capabilities as compared to existing sources. Our new source concept is based on a controlled interplay between the cascade and anomalous radiative trapping. Using specially designed advanced numerical models supported with analytical estimates, we demonstrate that the concept becomes feasible at laser powers of around 7 PW, which is accessible at soon-to-be-available facilities. A higher peak power of 40 PW can provide 1 09 photons with GeV energies in a well-collimated 3-fs beam, achieving peak brilliance 9 ×1024 ph s-1 mrad-2 mm-2/0.1 %BW .

  9. Dense water cascading, bottom currents and sediment wave formation at the exit of the Bari canyon (Southern Adriatic Sea, Italy)

    Science.gov (United States)

    Langone, Leonardo; Miserocchi, Stefano; Boldrin, Alfredo; Turchetto, Margherita; Foglini, Federica; Trincardi, Fabio

    2010-05-01

    The dense water forming in the North Adriatic (NAdDW) spreading southward along the Italian continental shelf, sinks in the Southern Adriatic basin through particular cascading events. Such events are seasonal, occurring specially in April, with variable intensity. These phenomena control the water mass mixing, the deep ocean ventilation, the behaviour of deep ecosystems, the formation of complex erosive and depositional bedforms and the abyssal export and burial of nutrients and carbon. Because of the NadDW formation is linked to climate factors (frequency, duration and size of Bura winds), the temporal variations of the NadDW dispersion into the Southern Adriatic allow to make inferences of the impact of recent climate changes on the ecosystems of the deep Mediterranean Sea. Previous research projects (EuroStrataform, HERMES) acquired a large data set of bathymetric, side-scan sonar (TOBI) and Chirp sonar profiles, which were used to build detailed morpho-bathymetric maps of the Southern Adriatic margin. There, the seabed is extremely complex, characterized by a large variety of bedforms (sediment waves, erosive scours, longitudinal furrows and giant comet marks). A branch of the cascading NAdDW is confined and accelerated through the Bari canyon where it produces a strong current capable of reaching down-slope velocities greater than 60 cm s-1 near the bottom at ~600 m of water depth, eroding the canyon thalweg and entraining large amounts of fine-grained sediment. At the exit of the canyon, in water depth greater than 800 m, the current becomes less confined, spreads laterally and generates an 80-km2-wide field of mud waves; these bedforms migrate up current and show amplitudes up to 50 m and wavelengths of about 1 km. Cruise IMPACT-09 of RV Urania was carried out in the Southern Adriatic Sea from 17-30 March 2009 with main scope of studying the impact of NadDW cascading events on the deep ecosystems of the Southern Adriatic. Experiments planned in the cruise

  10. Surface-emitting terahertz quantum cascade lasers with continuous-wave power in the tens of milliwatt range

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Gangyi, E-mail: gangyi.xu@mail.sitp.ac.cn [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France); Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Li, Lianhe; Giles Davies, A.; Linfield, Edmund H. [School of Electronic and Electrical Engineering, University of Leeds, Leeds LS9 2JT (United Kingdom); Isac, Nathalie; Halioua, Yacine; Colombelli, Raffaele, E-mail: raffaele.colombelli@u-psud.fr [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France)

    2014-03-03

    We demonstrate efficient surface-emitting terahertz frequency quantum cascade lasers with continuous wave output powers of 20–25 mW at 15 K and maximum operating temperatures of 80–85 K. The devices employ a resonant-phonon depopulation active region design with injector, and surface emission is realized using resonators based on graded photonic heterostructures (GPHs). GPHs can be regarded as energy wells for photons and have recently been implemented through grading the period of the photonic structure. In this paper, we show that it is possible to keep the period constant and grade instead the lateral metal coverage across the GPH. This strategy ensures spectrally single-mode operation across the whole laser dynamic range and represents an additional degree of freedom in the design of confining potentials for photons.

  11. Particle dynamics and spatial e-e+ density structures at QED cascading in circularly polarized standing waves

    Science.gov (United States)

    Bashinov, A. V.; Kumar, P.; Kim, A. V.

    2017-04-01

    We present a comprehensive analysis of longitudinal particle drifting in a standing circularly polarized wave at extreme intensities when quantum radiation reaction (RR) effects should be accounted for. To get an insight into the physics of this phenomenon we made a comparative study considering the RR force in the Landau-Lifshitz or quantum-corrected form, including the case of photon emission stochasticity. Specific features of particle dynamics have a strong impact on spatial structures of the electron-positron (e-e+ ) density created in vacuum through quantum electrodynamic (QED) cascades in counterpropagating laser pulses. Three-dimensional particle-in-cell modeling accounting for QED effects confirms realization of different pair plasma structures.

  12. Wave fronts and cascades of soliton interactions in the periodic two dimensional Volterra system

    Science.gov (United States)

    Bury, Rhys; Mikhailov, Alexander V.; Wang, Jing Ping

    2017-05-01

    In the paper we develop the dressing method for the solution of the two-dimensional periodic Volterra system with a period N. We derive soliton solutions of arbitrary rank k and give a full classification of rank 1 solutions. We have found a new class of exact solutions corresponding to wave fronts which represent smooth interfaces between two nonlinear periodic waves or a periodic wave and a trivial (zero) solution. The wave fronts are non-stationary and they propagate with a constant average velocity. The system also has soliton solutions similar to breathers, which resembles soliton webs in the KP theory. We associate the classification of soliton solutions with the Schubert decomposition of the Grassmannians GrR(k , N) and GrC(k , N) .

  13. Behaviour of Large Cylindrical Offshore Structures Subjected to Wave Loads

    Directory of Open Access Journals (Sweden)

    Begüm Yurdanur DAĞLI

    2017-08-01

    Full Text Available Spar-type and monopole substructures consisting of a large-diameter, single vertical cylinders have been used as wind turbine towers, oil storage platforms, tankers and wave energy converters at deepwater region in the sea. These towers and platforms are exposed to environmental forces such as wind, wave and current. Wave force is the most effective force in the total environmental force. The body disturbs the incident wave and Diffraction Theory is used for computing the pressure distribution for designing the structure. Therefore, this study aims to present the effect of structural design of towers on dynamic behavior due to wave actions. Two different cases of structural models are selected to employ bidirectional fluid structure interaction (FSI analysis. Diffraction Theory is utilized to investigate wave forces. Solid and fluid domains are modeled in Abaqus finite elements program. Behaviors of various types of offshore structures are evaluated and compared according to the significant stresses and displacements. The hydrodynamic pressure on the cylindrical structure surface and the diffraction forces acting on structures are presented. Mode shapes, first three natural frequencies are comparatively given.

  14. Broadband multiple-cascaded integration of electroabsorption modulators and high impedance transmission lines by lowering standing-wave effect.

    Science.gov (United States)

    Wu, Jui-Pin; Chen, Rui-Ren; Chiu, Yi-Jen

    2012-04-09

    Standing wave effect of applied electrical field on optical modulation in multiple-cascaded integration (CI) electroabsorption modulator (EAM) and high-impedance transmission line (HITL) has been investigated in this paper. As modulation frequency is increased to the scale that electrical wavelength is in the order of optical modulator length, multiple electrical reflection and self-interference on impedance-mismatch boundaries becomes significant, leading to strong position-dependent field distribution and degrading modulation bandwidth. Sharp bandwidth roll of electrical-optical (EO) conversion by standing wave has been found experimentally in CI structure, consistent with simulation results. By comparing different segment number and length of CI- structure, larger section number of design can overcome such problem to get more flatten bandwidth response. Such simple CI for 300μm long EAM has been demonstrated with flat EO response of -3dB drop 45GHz and -10dB microwave reflection (up to 65GHz) in 6-segement device, suggesting this scheme design is quite useful for efficient broad band modulation.

  15. Ultra-bright GeV photon source via controlled electromagnetic cascades in laser-dipole waves

    Science.gov (United States)

    Gonoskov, Arkady; Bashinov, Alexey; Efimenko, Evgeny; Muraviev, Alexander; Kim, Arkady; Ilderton, Anton; Bastrakov, Sergey; Meyerov, Iosif; Marklund, Mattias; Sergeev, Alexander

    2017-10-01

    The prospect of achieving conditions for triggering strong-field QED phenomena at upcoming large-scale laser facilities raises a number of intriguing questions. What kind of new effects and interaction regimes can be accessed by basic QED phenomena? What are the minimal (optimal) requirements to trigger these effects and enter these regimes? How can we, from this, gain new fundamental knowledge or create important applications? The talk will concern the prospects of producing high fluxes of GeV photons by triggering a special type of self-sustaining cascade in the field of several colliding laser pulses that form a dipole wave. Apart from reaching the highest field strength for a given total power of laser pulses, the dipole wave enables anomalous radiative trapping that favors pair production and high-energy photon generation. An extensive theoretical analysis and 3D QED-PIC simulations indicate that the concept is feasible at upcoming large-scale laser facilities of 10 PW level and can provide an extraordinary intense source of GeV photons for novel experimental studies in nuclear and quark-nuclear physics.

  16. Design and Realization Aspects of 1-THz Cascade Backward Wave Amplifier Based on Double Corrugated Waveguide

    DEFF Research Database (Denmark)

    Paoloni, Claudio; Di Carlo, Aldo; Bouamrane, Fayçal

    2013-01-01

    The design and fabrication challenges in the first ever attempt to realize a 1-THz vacuum tube amplifier are described. Implementation of innovative solutions including a slow-wave structure in the form of a double corrugated waveguide, lateral tapered input and output couplers, deep X-ray LIGA f...

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

    Science.gov (United States)

    Karki, Khadga J.

    2017-10-01

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

  18. Competing turbulent cascades and eddy-wave interactions in shallow water equilibria

    Science.gov (United States)

    Weichman, Peter B.

    2017-03-01

    In recent work, Renaud, Venaille, and Bouchet (RVB) [Renaud et al., J. Stat. Phys. 163, 784 (2016), 10.1007/s10955-016-1496-x] revisit the equilibrium statistical mechanics theory of the shallow water equations, within a microcanonical approach, focusing on a more careful treatment of the energy partition between inertial gravity wave and eddy motions in the equilibrium state and deriving joint probability distributions for the corresponding dynamical degrees of freedom. The authors derive a Liouville theorem that determines the underlying phase space statistical measure, but then, through some physical arguments, actually compute the equilibrium statistics using a measure that violates this theorem, choosing equal volume vs equal area fluid parcels. Here, using a more convenient, but essentially equivalent, grand canonical approach, the full statistical theory consistent with the Liouville theorem is derived. The results reveal several significant differences from the previous results (1) The microscale wave motions lead to a strongly fluctuating thermodynamics, including long-range correlations, in contrast to the mean-field-like behavior found by RVB. The final effective model is equivalent to that of an elastic membrane with a nonlinear wave-renormalized surface tension. (2) Even when a mean-field approximation is made, a rather more complex joint probability distribution is revealed. Alternative physical arguments fully support the consistency of the results. Of course, the true fluid final steady state relies on dissipative processes not included in the shallow water equations, such as wave breaking and viscous effects, but it is argued that the current theory provides a more mathematically consistent starting point for future work aimed at assessing their impacts.

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

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2010-04-01

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

  20. Gigabit radio-over-fiber link for converged baseband and millimeter-wave band signal transmission using cascaded injection-locked Fabry-Pérot laser diodes.

    Science.gov (United States)

    Hong, Moon-Ki; Won, Yong-Yuk; Han, Sang-Kook

    2009-05-11

    A novel scheme, for both baseband and millimeter-wave band gigabit data transmission in radio-over-fiber system, is proposed and experimentally demonstrated by using cascaded injection-locked Fabry- Pérot laser diodes. It was able to improve suppression ratio of carrier suppressed signal using the cascaded injection-locking. The suppression ratio improvement of the optical carrier suppressed signal of 20 dB was verified. Applying this mechanism, 60-GHz millimeter-wave carrier of enhanced signal quality could be accomplished. Its peak power and phase noise were obtained as -40 dBm and -103.5 dBm/Hz respectively, which was suitable for 60-GHz data transmission. In addition, a successful bidirectional transmission of 1.25-Gbps wired and wireless data was achieved by adopting remodulation technique using a gain-saturated reflective semiconductor optical amplifier for uplink.

  1. Nonlinear Passive Control of a Wave Energy Converter Subject to Constraints in Irregular Waves

    Directory of Open Access Journals (Sweden)

    Liguo Wang

    2015-06-01

    Full Text Available This paper investigates a passive control method of a point absorbing wave energy converter by considering the displacement and velocity constraints under irregular waves in the time domain. A linear generator is used as a power take-off unit, and the equivalent damping force is optimized to improve the power production of the wave energy converter. The results from nonlinear and linear passive control methods are compared, and indicate that the nonlinear passive control method leads to the excitation force in phase with the velocity of the converter that can significantly improve the energy production of the converter.

  2. Watt-Level Continuous-Wave Emission from a Bi-Functional Quantum Cascade Laser/Detector

    Science.gov (United States)

    2017-04-18

    Faist, J. Quantum -cascade-laser structures as photodetectors. Applied Physics Letters 2002, 81, 2683. (17) Gendron, L.; Carras, M.; Huynh, A.; Ortiz, V...Koeniguer, C.; Berger, V. Quantum cascade photodetector. Applied Physics Letters 2004, 85, 2824. (18) Reininger, P.; Zederbauer, T.; Schwarz, B...Detz, H.; MacFarland, D.; Andrews, A. M.; Schrenk, W.; Strasser, G. InAs/AlAsSb based quantum cascade detector. Applied Physics Letters 2015, 107

  3. Cascading pulse tubes on a large diaphragm pressure wave generator to increase liquefaction potential

    Science.gov (United States)

    Caughley, A.; Meier, J.; Nation, M.; Reynolds, H.; Boyle, C.; Tanchon, J.

    2017-12-01

    Fabrum Solutions, in collaboration with Absolut System and Callaghan Innovation, produce a range of large pulse tube cryocoolers based on metal diaphragm pressure wave generator technology (DPWG). The largest cryocooler consists of three in-line pulse tubes working in parallel on a 1000 cm3 swept volume DPWG. It has demonstrated 1280 W of refrigeration at 77 K, from 24 kW of input power and was subsequently incorporated into a liquefaction plant to produce liquid nitrogen for an industrial customer. The pulse tubes on the large cryocooler each produced 426 W of refrigeration at 77 K. However, pulse tubes can produce more refrigeration with higher efficiency at higher temperatures. This paper presents the results from experiments to increase overall liquefaction throughput by operating one or more pulse tubes at a higher temperature to pre-cool the incoming gas. The experiments showed that the effective cooling increased to 1500 W resulting in an increase in liquefaction rate from 13 to 16 l/hour.

  4. Comparison of the VISX WaveScan and OPD-Scan Ⅲ with the subjective refraction

    Directory of Open Access Journals (Sweden)

    Ran Zhu

    2014-10-01

    Full Text Available AIM: To compare the refractive errors measured by the VISX WaveScan, OPD-Scan Ⅲ and the subjective refraction.METHODS: Seventy-six patients(152 eyeswere recruited from January 2013 to December 2013. All patients were measured with subjective refraction by the phoropter(NIDEK, RT-5 100, objective refraction by the WaveScan(AMO Company, USA, OPD-Scan Ⅲ(Nidek Technologies, Japan. The sphere, cylinder, axis of the three methods were compared and analyzed.RESULTS: The sphere measured by WaveScan was lower than that by subjective refraction, the difference was 0.13±0.30D(t=3.753, Pt=3.664, PP>0.05. The value of the difference between WaveScan and subjective refraction was 5.87°±6.19° for the axis and the difference between OPD-Scan Ⅲ and subjective refraction was 3.82°±3.95°. There was statistic significance(t=2.817, P=0.006. CONCLUSION: For sphere and cylinder,WaveScan generated some deviation relative to subjective refraction. The Nidek OPD-Scan Ⅲ gives more accurate measures of objective refraction when compared with subjective refraction.

  5. Running interfacial waves in a two-layer fluid system subject to longitudinal vibrations.

    Science.gov (United States)

    Goldobin, D S; Pimenova, A V; Kovalevskaya, K V; Lyubimov, D V; Lyubimova, T P

    2015-05-01

    We study the waves at the interface between two thin horizontal layers of immiscible fluids subject to high-frequency horizontal vibrations. Previously, the variational principle for energy functional, which can be adopted for treatment of quasistationary states of free interface in fluid dynamical systems subject to vibrations, revealed the existence of standing periodic waves and solitons in this system. However, this approach does not provide regular means for dealing with evolutionary problems: neither stability problems nor ones associated with propagating waves. In this work, we rigorously derive the evolution equations for long waves in the system, which turn out to be identical to the plus (or good) Boussinesq equation. With these equations one can find all the time-independent-profile solitary waves (standing solitons are a specific case of these propagating waves), which exist below the linear instability threshold; the standing and slow solitons are always unstable while fast solitons are stable. Depending on initial perturbations, unstable solitons either grow in an explosive manner, which means layer rupture in a finite time, or falls apart into stable solitons. The results are derived within the long-wave approximation as the linear stability analysis for the flat-interface state [D.V. Lyubimov and A.A. Cherepanov, Fluid Dynamics 21, 849 (1986)] reveals the instabilities of thin layers to be long wavelength.

  6. Wave-speed-determined flow limitation at peak flow in normal and asthmatic subjects.

    Science.gov (United States)

    Pedersen, O F; Brackel, H J; Bogaard, J M; Kerrebijn, K F

    1997-11-01

    The purpose of this study was to examine whether peak expiratory flow is determined by the wave-speed flow-limiting mechanism. We examined 17 healthy subjects and 11 subjects with stable asthma, the latter treated with inhaled bronchodilators and corticosteroids. We used an esophageal balloon and a Pitot-static probe positioned at five locations between the right lower lobe and midtrachea to obtain dynamic area-transmural pressure (A-Ptm) curves as described (O. F. Pedersen, B. Thiessen, and S. Lyager. J. Appl. Physiol. 52: 357-369, 1982). From these curves we obtained cross-sectional area (A) and airway compliance (Caw = dA/dPtm) at PEF, calculated flow at wave speed (Vws = A[A/(Caw*rho)0.5], where rho is density) and speed index is (SI = V/Vws). In 13 of 15 healthy and in 4 of 10 asthmatic subjects, who could produce satisfactory curves, SI at PEF was > 0.9 at one or more measured positions. Alveolar pressure continued to increase after PEF was achieved, suggesting flow limitation somewhere in the airway in all of these subjects. We conclude that wave speed is reached in central airways at PEF in most subjects, but it cannot be excluded that wave speed is also reached in more peripheral airways.

  7. Dynamic Response of Offshore Wind Turbines subjected to Joint Wave and Wind Loads

    DEFF Research Database (Denmark)

    Liu, Weiliang; Chen, Jianbing; Liu, Wenfeng

    2013-01-01

    This paper investigates the dynamic response of offshore wind turbine systems subjected joint wind and wave loads. Relying on the finite element model, Kane’s equation is adopted to consider the rotation of blades. Besides, the generator-torque control and blade-pitch control are taken into consi...

  8. Dynamic Response of Underground Circular Lining Tunnels Subjected to Incident P Waves

    Directory of Open Access Journals (Sweden)

    Hua Xu

    2014-01-01

    Full Text Available Dynamic stress concentration in tunnels and underground structures during earthquakes often leads to serious structural damage. A series solution of wave equation for dynamic response of underground circular lining tunnels subjected to incident plane P waves is presented by Fourier-Bessel series expansion method in this paper. The deformation and stress fields of the whole medium of surrounding rock and tunnel were obtained by solving the equations of seismic wave propagation in an elastic half space. Based on the assumption of a large circular arc, a series of solutions for dynamic stress were deduced by using a wave function expansion approach for a circular lining tunnel in an elastic half space rock medium subjected to incident plane P waves. Then, the dynamic response of the circular lining tunnel was obtained by solving a series of algebraic equations after imposing its boundary conditions for displacement and stress of the circular lining tunnel. The effects of different factors on circular lining rock tunnels, including incident frequency, incident angle, buried depth, rock conditions, and lining stiffness, were derived and several application examples are presented. The results may provide a good reference for studies on the dynamic response and aseismic design of tunnels and underground structures.

  9. Subjective loudness and annoyance of filtered N-wave sonic booms.

    Science.gov (United States)

    Niedzwiecki, A; Ribner, H S

    1979-03-01

    The contribution of the "infrasonic" low-frequency content of sonic boom N waves to subjective loudness and annoyance has been investigated. An extended low-frequency response loudspeaker-driven simulation booth was employed, with computer-generated input test signals. For test N waves of 1 ms rise time and 150 ms duration, frequencies below 25 and 50 Hz, respectively, were cut off by digital filters simulating simple RC circuits. The filtered signal amplitude was adjusted versus the amplitude (48 Pa) of a reference unfiltered N wave (effective low-frequency cutoff approximately 0.1 Hz) until the two sounded equally loud (first experiment) or equally annoying (second experiment). The amplitude differences for equality were very slight: less than 0.6 dB at most. Surprisingly, while loss of the low frequencies slightly decreased the loudness, it slightly increased the annoyance.

  10. Generation of reactive oxygen species in 1-methyl-4-phenylpyridinium (MPP+ treated dopaminergic neurons occurs as an NADPH oxidase-dependent two-wave cascade

    Directory of Open Access Journals (Sweden)

    Das Mita

    2011-10-01

    Full Text Available Abstract Background Reactive oxygen species (ROS, superoxide and hydrogen peroxide (H2O2, are necessary for appropriate responses to immune challenges. In the brain, excess superoxide production predicts neuronal cell loss, suggesting that Parkinson's disease (PD with its wholesale death of dopaminergic neurons in substantia nigra pars compacta (nigra may be a case in point. Although microglial NADPH oxidase-produced superoxide contributes to dopaminergic neuron death in an MPTP mouse model of PD, this is secondary to an initial die off of such neurons, suggesting that the initial MPTP-induced death of neurons may be via activation of NADPH oxidase in neurons themselves, thus providing an early therapeutic target. Methods NADPH oxidase subunits were visualized in adult mouse nigra neurons and in N27 rat dopaminergic cells by immunofluorescence. NADPH oxidase subunits in N27 cell cultures were detected by immunoblots and RT-PCR. Superoxide was measured by flow cytometric detection of H2O2-induced carboxy-H2-DCFDA fluorescence. Cells were treated with MPP+ (MPTP metabolite following siRNA silencing of the Nox2-stabilizing subunit p22phox, or simultaneously with NADPH oxidase pharmacological inhibitors or with losartan to antagonize angiotensin II type 1 receptor-induced NADPH oxidase activation. Results Nigral dopaminergic neurons in situ expressed three subunits necessary for NADPH oxidase activation, and these as well as several other NADPH oxidase subunits and their encoding mRNAs were detected in unstimulated N27 cells. Overnight MPP+ treatment of N27 cells induced Nox2 protein and superoxide generation, which was counteracted by NADPH oxidase inhibitors, by siRNA silencing of p22phox, or losartan. A two-wave ROS cascade was identified: 1 as a first wave, mitochondrial H2O2 production was first noted at three hours of MPP+ treatment; and 2 as a second wave, H2O2 levels were further increased by 24 hours. This second wave was eliminated by

  11. Laser-tissue interaction of a continuous-wave 2-μm, 3-μm cascade oscillation fiber laser: sharp incision with controlled coagulation layer thickness

    Science.gov (United States)

    Arai, Tsunenori; Sumiyoshi, Tetsumi; Naruse, Kyota; Ishihara, Miya; Sato, Shunichi; Kikuchi, Makoto; Kasamatsu, Tadashi; Sekita, Hitoshi; Obara, Minoru

    2000-06-01

    We studied coagulation layer controlled incision with newly developed continuous wave 2 micrometer, 3 micrometer cascade oscillation fiber laser in vitro. Since this laser device simultaneously oscillates 2 micrometer and 3 micrometer radiation, we could change tissue interaction by arranging power ratio of 2 micrometer to 3 micrometer radiation. About one watt of total irradiation power with various power ratios was focused to extracted fresh porcine myocardium or anesthetized rabbit on an automatic moving stage to obtain line incision. Macro photograph and microscopic histology were used to observe tissue interaction phenomenon. The incised specimen showed that precise cutting groove with thin coagulation layer was attained by a 3 micrometer based radiation, meanwhile addition of 2 micrometer radiation to 3 micrometer radiation made coagulation layer thicker. A heat conduction simulator using finite-element method was used to qualitatively explain obtained coagulation layer thickness. This precise incision with controllable side coagulation layer may effective to control bleeding during incision, for instance, for skin, liver, and kidney incisions. Pure continuous wave radiation of 2 micrometer and 3 micrometer may eliminate stress wave induced tissue damage which is frequently found in Ho:YAG and/or Er:YAG tissue interactions. Moreover, sapphire fiber might offer flexible power delivery to this new laser to establish endoscopic application and/or to improved beam handling.

  12. High power, widely tunable, mode-hop free, continuous wave external cavity quantum cascade laser for multi-species trace gas detection

    Energy Technology Data Exchange (ETDEWEB)

    Centeno, R.; Marchenko, D.; Mandon, J.; Cristescu, S. M.; Harren, F. J. M., E-mail: F.Harren@science.ru.nl [Life Science Trace Gas Facility, Molecular and Laser Physics, Institute for Molecules and Materials, Radboud University, P.O. Box 9010, NL-6500 GL Nijmegen (Netherlands); Wulterkens, G. [TechnoCentrum, Radboud University, Heyendaalseweg 135, 6525AJ Nijmegen (Netherlands)

    2014-12-29

    We present a high power, widely tunable, continuous wave external cavity quantum cascade laser designed for infrared vibrational spectroscopy of molecules exhibiting broadband and single line absorption features. The laser source exhibits single mode operation with a tunability up to 303 cm{sup −1} (∼24% of the center wavelength) at 8 μm, with a maximum optical output power of 200 mW. In combination with off-axis integrated output spectroscopy, trace-gas detection of broadband absorption gases such as acetone was performed and a noise equivalent absorption sensitivity of 3.7 × 10{sup −8 }cm{sup −1 }Hz{sup −1/2} was obtained.

  13. Performance of Pre-Stressed Sandwich Composites Subjected to Shock Wave Loading

    Directory of Open Access Journals (Sweden)

    Shukla A.

    2010-06-01

    Full Text Available The present paper experimentally studies the dynamic behaviour of prestressed sandwich composites under blast loading. The in-plane static compression loadings are implemented on the sandwich composites before they are subjected to the transverse shock wave loading. Three different pre-stress levels are chosen. 3-D realtime deformation data are captured by two high-speed photography systems: a backview Digital Image Correlation (DIC system and a side-view camera system. The results show that pre-stresses can induce local buckling in the front face-sheet of sandwich composites, consequently reduce the blast resistance of sandwich composites.

  14. Autocorrelation and Cross-Correlation Analyses of Alpha Waves in Reflection to Subjective Preference of a Flickering Light

    National Research Council Canada - National Science Library

    Soeta, Y

    2001-01-01

    To clarify the relationship between the human brain activity and subjective preference of a flickering light under changing temporal frequency and mean luminance, alpha waves were analyzed by autocorrelation function (ACF...

  15. Reduced Slow-Wave Rebound during Daytime Recovery Sleep in Middle-Aged Subjects

    Science.gov (United States)

    Lafortune, Marjolaine; Gagnon, Jean-François; Latreille, Véronique; Vandewalle, Gilles; Martin, Nicolas; Filipini, Daniel; Doyon, Julien; Carrier, Julie

    2012-01-01

    Cortical synchronization during NREM sleep, characterized by electroencephalographic slow waves (SW 75 µV), is strongly related to the number of hours of wakefulness prior to sleep and to the quality of the waking experience. Whether a similar increase in wakefulness length leads to a comparable enhancement in NREM sleep cortical synchronization in young and older subjects is still a matter of debate in the literature. Here we evaluated the impact of 25-hours of wakefulness on SW during a daytime recovery sleep episode in 29 young (27y ±5), and 34 middle-aged (51y ±5) subjects. We also assessed whether age-related changes in NREM sleep cortical synchronization predicts the ability to maintain sleep during daytime recovery sleep. Compared to baseline sleep, sleep efficiency was lower during daytime recovery sleep in both age-groups but the effect was more prominent in the middle-aged than in the young subjects. In both age groups, SW density, amplitude, and slope increased whereas SW positive and negative phase duration decreased during daytime recovery sleep compared to baseline sleep, particularly in anterior brain areas. Importantly, compared to young subjects, middle-aged participants showed lower SW density rebound and SW positive phase duration enhancement after sleep deprivation during daytime recovery sleep. Furthermore, middle-aged subjects showed lower SW amplitude and slope enhancements after sleep deprivation than young subjects in frontal and prefrontal derivations only. None of the SW characteristics at baseline were associated with daytime recovery sleep efficiency. Our results support the notion that anterior brain areas elicit and may necessitate more intense recovery and that aging reduces enhancement of cortical synchronization after sleep loss, particularly in these areas. Age-related changes in the quality of wake experience may underlie age-related reduction in markers of cortical synchronization enhancement after sustained wakefulness. PMID

  16. Reduced slow-wave rebound during daytime recovery sleep in middle-aged subjects.

    Directory of Open Access Journals (Sweden)

    Marjolaine Lafortune

    Full Text Available Cortical synchronization during NREM sleep, characterized by electroencephalographic slow waves (SW 75 µV, is strongly related to the number of hours of wakefulness prior to sleep and to the quality of the waking experience. Whether a similar increase in wakefulness length leads to a comparable enhancement in NREM sleep cortical synchronization in young and older subjects is still a matter of debate in the literature. Here we evaluated the impact of 25-hours of wakefulness on SW during a daytime recovery sleep episode in 29 young (27 y ± 5, and 34 middle-aged (51 y ± 5 subjects. We also assessed whether age-related changes in NREM sleep cortical synchronization predicts the ability to maintain sleep during daytime recovery sleep. Compared to baseline sleep, sleep efficiency was lower during daytime recovery sleep in both age-groups but the effect was more prominent in the middle-aged than in the young subjects. In both age groups, SW density, amplitude, and slope increased whereas SW positive and negative phase duration decreased during daytime recovery sleep compared to baseline sleep, particularly in anterior brain areas. Importantly, compared to young subjects, middle-aged participants showed lower SW density rebound and SW positive phase duration enhancement after sleep deprivation during daytime recovery sleep. Furthermore, middle-aged subjects showed lower SW amplitude and slope enhancements after sleep deprivation than young subjects in frontal and prefrontal derivations only. None of the SW characteristics at baseline were associated with daytime recovery sleep efficiency. Our results support the notion that anterior brain areas elicit and may necessitate more intense recovery and that aging reduces enhancement of cortical synchronization after sleep loss, particularly in these areas. Age-related changes in the quality of wake experience may underlie age-related reduction in markers of cortical synchronization enhancement after

  17. DEVELOPING OF ELECTRONIC TEACHING MATERIAL BASED ON MOBILE LEARNING IN THE WAVE SUBJECTS

    Directory of Open Access Journals (Sweden)

    D. H. Rif’ati

    2015-07-01

    Full Text Available In the advanced and modern era, technological sophistication led to learning which initially runs, in which teachers and students meet each other and communicate in the classroom, can be implemented through of information technology. Along with the development of information, where books and teachers who initially as a primary source of learning, are now beginning to experience growth from the internet. Mobile learning defined as mobile devices that are used in the learning process. The wave course is one of subject that must be taken by students of physics education in the third semester. This course emphasizes the concepts of wave were reviewed mathematically and the phenomenon that occurs in everyday life. Mobile learning developed in this study in the form of electronic teaching materials on subjects of waves. The aim of this study was to develop electronic teaching material in the form of mobile learning. The sample of this study is 80 students in the third semester students who are taking waves courses. The results show that mobile learning that has been developed has score 3.8 and included valid criteria. Pada era yang serba maju dan modern, kecanggihan teknologi menyebabkan pembelajaran yang awalnya berjalan satu arah, dimana guru dan siswa saling bertemu dan berkomunikasi di dalam kelas, dapat dilaksanakan melalui bantuan teknologi.informasi. Seiring dengan perkembangan informasi, buku dan guru yang awalnya sebagai sumber belajar utama, saat ini sudah mulai mengalami perkembangan dimana sumber belajar yang berasal dari internet sudah mulai sering dimanfaatkan dalam proses pembelajaran. Mobile larning didefinisikan sebagai perangkat mobile yang dipergunakan dalam proses belajar mengajar. Mata kuliah gelombang sendiri merupakan salah satu mata kuliah yang wajib ditempuh oleh mahasiswa program studi pendidikan fisika semester 3. Mata kuliah ini menekankan pada konsep gelombang yang ditinjau secara matematis dan fenomenanya yang terjadi

  18. Relationships of CRP and P wave dispersion with atrial fibrillation in hypertensive subjects.

    Science.gov (United States)

    Tsioufis, Costas; Syrseloudis, Dimitris; Hatziyianni, Awalia; Tzamou, Vanessa; Andrikou, Ioannis; Tolis, Panaglotis; Toutouzas, Kostas; Michaelidis, Andreas; Stefanadis, Christodoulos

    2010-02-01

    Although inflammation has been shown to be implicated in the pathophysiology of atrial fibrillation (AF), little is known about its involvement in the accompanying atrial electrical remodeling expressed by P wave dispersion (P(disp)). Fifty hypertensive subjects with documented paroxysmal AF (AF group) and 50 matched for body mass index, sex and office systolic blood pressure (BP) subjects with no history of AF (SR group) were subjected to electrocardiogram (ECG) and P(disp) assessment, hs-CRP determination, a complete echocardiographic study and 24-h ambulatory BP monitoring. The AF as compared to the SR subjects were older by 14 years (P < 0.0001) and they exhibited lower office and 24-h diastolic BP (7 mm Hg, P < 0.0001 and by 8 mm Hg, P < 0.0001, respectively) and higher office and 24-h pulse pressure (by 4 mm Hg, P = 0.03 and 6 mm Hg, P = 0.001, respectively) mean values. A higher mean of left atrial (LA) diameter index (by 1.9 mm/m(2), P < 0.0001) and left ventricular mass index (by 16 g/m(2), P < 0.0001) were observed in the AF vs. SR group. P(disp) mean and hs-CRP median values were higher in the AF group (by 22 ms, P < 0.0005 and by 4.63 mg/l, P < 0.0005, respectively). Standard multiple and multiple logistic regression analysis identified log(10)(hs-CRP) as independent determinant of P(disp) and log(10)(CRP) and P(disp) as independent determinants of AF. In hypertensive subjects hs-CRP and P(disp) are interrelated and associated with AF, suggesting an active implication of inflammation in the atrial electrophysiological remodeling predisposing to AF.

  19. Electro-optic millimeter-wave harmonic downconversion and vector demodulation using cascaded phase modulation and optical filtering.

    Science.gov (United States)

    Pagán, Vincent R; Murphy, Thomas E

    2015-06-01

    We describe and demonstrate an electro-optic technique to simultaneously downconvert and demodulate vector-modulated millimeter-wave signals. The system uses electro-optic phase modulation and optical filtering to perform harmonic downconversion of the RF signal to an intermediate frequency (IF) or to baseband. We demonstrate downconversion of RF signals between 7 and 70-GHz to IFs below 20-GHz. Furthermore, we show harmonic downconversion and vector demodulation of 2.5-Gb/s QPSK and 5-Gb/s 16-QAM signals at carrier frequencies of 40-GHz to baseband.

  20. Alfvén wave interaction with inhomogeneous plasmas: acceleration and energy cascade towards small-scales

    Directory of Open Access Journals (Sweden)

    V. Génot

    2004-06-01

    Full Text Available Investigating the process of electron acceleration in auroral regions, we present a study of the temporal evolution of the interaction of Alfvén waves (AW with a plasma inhomogeneous in a direction transverse to the static magnetic field. This type of inhomogeneity is typical of the density cavities extended along the magnetic field in auroral acceleration regions. We use self-consistent Particle In Cell (PIC simulations which are able to reproduce the full nonlinear evolution of the electromagnetic waves, as well as the trajectories of ions and electrons in phase space. Physical processes are studied down to the ion Larmor radius and electron skin depth scales. We show that the AW propagation on sharp density gradients leads to the formation of a significant parallel (to the magnetic field electric field (E-field. It results from an electric charge separation generated on the density gradients by the polarization drift associated with the time varying AW E-field. Its amplitude may reach a few percents of the AW E-field. This parallel component accelerates electrons up to keV energies over a distance of a few hundred Debye lengths, and induces the formation of electron beams. These beams trigger electrostatic plasma instabilities which evolve toward the formation of nonlinear electrostatic structures (identified as electron holes and double layers. When the electrostatic turbulence is fully developed we show that it reduces the further wave/particle exchange. This sequence of mechanisms is analyzed with the program WHAMP, to identify the instabilities at work and wavelet analysis techniques are used to characterize the regime of energy conversions (from electromagnetic to electrostatic structures, from large to small length scales. This study elucidates a possible scenario to account for the particle acceleration and the wave dissipation in inhomogeneous plasmas. It would consist of successive phases of acceleration along the magnetic field

  1. Subjectivity

    Directory of Open Access Journals (Sweden)

    Jesús Vega Encabo

    2015-11-01

    Full Text Available In this paper, I claim that subjectivity is a way of being that is constituted through a set of practices in which the self is subject to the dangers of fictionalizing and plotting her life and self-image. I examine some ways of becoming subject through narratives and through theatrical performance before others. Through these practices, a real and active subjectivity is revealed, capable of self-knowledge and self-transformation. 

  2. ABCA1-dependent serum cholesterol efflux capacity inversely correlates with pulse wave velocity in healthy subjects.

    Science.gov (United States)

    Favari, Elda; Ronda, Nicoletta; Adorni, Maria Pia; Zimetti, Francesca; Salvi, Paolo; Manfredini, Matteo; Bernini, Franco; Borghi, Claudio; Cicero, Arrigo F G

    2013-01-01

    The capacity of HDL to induce cell cholesterol efflux is considered one of its main antiatherogenic properties. Little is known about the impact of such HDL function on vascular physiology. We investigated the relationship between ABCA1-dependent serum cholesterol efflux capacity (CEC), an HDL functionality indicator, and pulse wave velocity (PWV), an indicator of arterial stiffness. Serum of 167 healthy subjects was used to conduct CEC measurement, and carotid-femoral PWV was measured with a high-fidelity tonometer. J774 macrophages, labeled with [(3)H]cholesterol and stimulated to express ABCA1, were exposed to sera; the difference between cholesterol efflux from stimulated and unstimulated cells provided specific ABCA1-mediated CEC. PWV is inversely correlated with ABCA1-dependent CEC (r = -0.183; P = 0.018). Moreover, controlling for age, sex, body mass index, mean arterial pressure, serum LDL, HDL-cholesterol, and fasting plasma glucose, PWV displays a significant negative regression on ABCA1-dependent CEC (β = -0.204; 95% confidence interval, -0.371 to -0.037). The finding that ABCA1-dependent CEC, but not serum HDL cholesterol level (r = -0.002; P = 0.985), is a significant predictor of PWV in healthy subjects points to the relevance of HDL function in vascular physiology and arterial stiffness prevention.

  3. Experimental Investigation of Wave Velocity-Permeability Model for Granite Subjected to Different Temperature Processing

    Directory of Open Access Journals (Sweden)

    Guanghui Jiang

    2017-01-01

    Full Text Available Understanding the change of permeability of rocks before and after heating is of great significance for exploitation of hydrocarbon resources and disposal of nuclear waste. The rock permeability under high temperature cannot be measured with most of the existing methods. In this paper, quality, wave velocity, and permeability of granite specimen from Maluanshan tunnel are measured after high temperature processing. Quality and wave velocity of granite decrease and permeability of granite increases with increasing temperature. Using porosity as the medium, a new wave velocity-permeability model is established with modified wave velocity-porosity formula and Kozeny-Carman formula. Under some given wave velocities and corresponding permeabilities through experiment, the permeabilities at different temperatures and wave velocities can be obtained. By comparing the experimental and the theoretical results, the proposed formulas are verified. In addition, a sensitivity analysis is performed to examine the effect of particle size, wave velocities in rock matrix, and pore fluid on permeability: permeability increases with increasing particle size, wave velocities in rock matrix, and pore fluid; the higher the rock wave velocity, the lower the effect of wave velocities in rock matrix and pore fluid on permeability.

  4. Six-Year Outcome of Subjects Without Overt Heart Disease With an Early Repolarization/J Wave Electrocardiographic Pattern.

    Science.gov (United States)

    Lanza, Gaetano Antonio; Argirò, Alessia; Mollo, Roberto; De Vita, Antonio; Spera, Francesco; Golino, Michele; Rota, Elisabetta; Filice, Monica; Crea, Filippo

    2017-12-01

    "Early repolarization" (ER) is a frequent finding at standard electrocardiogram (ECG). In this study we assessed whether ER is associated with an increased risk of events, as recently suggested by some studies. We prospectively enrolled 4,176 consecutive subjects without any heart disease who underwent routine ECG recording. ER was diagnosed in case of typical concave ST-segment elevation ≥0.1 mV; a J wave was diagnosed when the QRS showed a notch or a slur in its terminal part. In this study we compared the 6-year outcome of all 687 subjects with ER/J wave and 687 matched subjects without ER/J wave (controls). Both groups included 335 males and 352 females, and age was 48.8 ± 18 years. Overall, 145 deaths occurred (11%), only 11 of which attributed to cardiac causes. No sudden death was reported. Cardiac deaths occurred in 5 (0.8%) and 6 (0.9%) ER/J wave subjects and controls, respectively (odds ratio [OR] 0.85, 95% confidence interval [CI] 0.26 to 2.80, p = 0.79). Both ER (OR 1.68, 95% CI 0.21 to 13.3, p = 0.62) and J wave (OR 0.91, 95% CI 0.28 to 3.00, p = 0.88) showed no association with cardiac death. Total mortality was 11.5% in the ER/J wave group and 10.6% in the control group (OR 1.10, 95% CI 0.78 to 1.56, p = 0.58). Both ER (OR 0.44, 95% CI 0.16 to 1.24, p = 0.12) and J wave (OR 1.20, 95% CI 0.85 to 1.70, p = 0.30) showed also no association with all-cause death. In subjects without any evidence of heart disease, we found no significant association of ER/J wave with the risk of cardiac, as well as all-cause, death at medium-term follow-up. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Learning Cascading

    CERN Document Server

    Covert, Michael

    2015-01-01

    This book is intended for software developers, system architects and analysts, big data project managers, and data scientists who wish to deploy big data solutions using the Cascading framework. You must have a basic understanding of the big data paradigm and should be familiar with Java development techniques.

  6. Cascades in helical turbulence

    CERN Document Server

    Ditlevsen, P D

    2001-01-01

    The existence of a second quadratic inviscid invariant, the helicity, in a turbulent flow leads to coexisting cascades of energy and helicity. An equivalent of the four-fifth law for the longitudinal third order structure function, which is derived from energy conservation, is easily derived from helicity conservation cite{Procaccia,russian}. The ratio of dissipation of helicity to dissipation of energy is proportional to the wave-number leading to a different Kolmogorov scale for helicity than for energy. The Kolmogorov scale for helicity is always larger than the Kolmogorov scale for energy so in the high Reynolds number limit the flow will always be helicity free in the small scales, much in the same way as the flow will be isotropic and homogeneous in the small scales. A consequence is that a pure helicity cascade is not possible. The idea is illustrated in a shell model of turbulence.

  7. Seismic Waves Scattering Impact through Tunnel Excavation on Adjacent Monuments Subjected to Far Field Earthquakes

    Directory of Open Access Journals (Sweden)

    Ghobakhloo E.

    2015-09-01

    Full Text Available The study of the effect of seismic wave scattering has attracted extensive attention in the past couple of decades especially in infrastructures like tunnels. A seismic wave, meeting the tunnel, can generate scattering which, in most cases, may incur damages in adjacent structures. In this study, using Finite Element Method (FEM, the effect of seismic wave scattering in far field has been investigated. The twin tunnels of Shiraz subway system are selected as the case study in this research and three far field seismic waves were chosen for time history analyses. Investigating the normal mode (before tunnel construction in comparison to the excavation mode (after tunnel construction enables calculation of the effect of displacement in adjacent structures. The analysis results indicate there is a significant difference between before and after tunnel construction (P-value<0.05. Accordingly, the influence of constructing a tunnel on adjacent surface structures is very important for tunnel design.

  8. Change Analysis of Laser Scans of Laboratory Rock Slopes Subject to Wave Attack Testing

    Science.gov (United States)

    Shen, Y.; Lindenbergh, R.; Hofland, B.; Kramer, R.

    2017-09-01

    For better understanding how coastal structures with gentle slopes behave during high energy events, a wave attack experiment representing a storm of 3000 waves was performed in a flume facility. Two setups with different steepness of slope were compared under the same conditions. In order to quantify changes in the rock slopes after the wave attack, a terrestrial laser scanner was used to obtain 3D coordinates of the rock surface before and after each experiment. Next, through a series of processing steps, the point clouds were converted to a suitable 2D raster for change analysis. This allowed to estimate detailed and quantitative change information. The results indicate that the area around the artificial coast line, defined as the intersection between sloped surface and wave surface, is most strongly affected by wave attacks. As the distances from the sloped surface to the waves are shorter, changes for the mildly sloped surface, slope 1 (1 : 10), are distributed over a larger area compared to the changes for the more steeply sloped surface, slope 2 (1 : 5). The results of this experiment show that terrestrial laser scanning is an effective and feasible method for change analysis of rock slopes in a laboratory setting. Most striking results from a process point of view is that the transport direction of the rocks change between the two different slopes: from seaward transport for the steeper slope to landward transport for the milder slope.

  9. Expenditure Cascades

    OpenAIRE

    Frank, R; Levine, A.; Dijk, O.

    2014-01-01

    Prevailing economic models of consumer behavior completely ignore the well-documented link between context and evaluation. We propose and test a theory that explicitly incorporates this link. Changes in one group's spending shift the frame of reference that defines consumption standards for others just below them on the income scale, giving rise to expenditure cascades. Our model, a descendant of James Duesenberry's relative income hypothesis, predicts the observed ways in which individual sa...

  10. ABCA1-dependent serum cholesterol efflux capacity inversely correlates with pulse wave velocity in healthy subjects[S

    OpenAIRE

    Favari, Elda; Ronda, Nicoletta; Adorni, Maria Pia; Zimetti, Francesca; Salvi, Paolo; Manfredini, Matteo; Bernini, Franco; Borghi, Claudio; Cicero, Arrigo F. G.

    2013-01-01

    The capacity of HDL to induce cell cholesterol efflux is considered one of its main antiatherogenic properties. Little is known about the impact of such HDL function on vascular physiology. We investigated the relationship between ABCA1-dependent serum cholesterol efflux capacity (CEC), an HDL functionality indicator, and pulse wave velocity (PWV), an indicator of arterial stiffness. Serum of 167 healthy subjects was used to conduct CEC measurement, and carotid-femoral PWV was measured with a...

  11. Negative Pressures and Spallation in Water Drops Subjected to Nanosecond Shock Waves.

    Science.gov (United States)

    Stan, Claudiu A; Willmott, Philip R; Stone, Howard A; Koglin, Jason E; Liang, Mengning; Aquila, Andrew L; Robinson, Joseph S; Gumerlock, Karl L; Blaj, Gabriel; Sierra, Raymond G; Boutet, Sébastien; Guillet, Serge A H; Curtis, Robin H; Vetter, Sharon L; Loos, Henrik; Turner, James L; Decker, Franz-Josef

    2016-06-02

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below -100 MPa were reached in the drops. We model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.

  12. Effect of Extracorporeal Shock Wave Therapy on Hamstring Tightness in Healthy Subjects: A Pilot Study.

    Science.gov (United States)

    Kim, Yong Wook; Chang, Won Hyuk; Kim, Na Young; Kwon, Jun Beom; Lee, Sang Chul

    2017-05-01

    To assess the effect of extracorporeal shock wave therapy (ESWT) for healthy participants with hamstring tightness. This study was performed at a university rehabilitation hospital. Twenty nine healthy adults with hamstring tightness were enrolled and randomly allocated into four groups (ESWT, stretching exercise, ESWT with stretching exercise, and control). The effects of individual treatments were compared by the finger-to-floor test and popliteal angle. The ESWT group, stretching exercise group and ESWT with stretching exercise group had decreased finger-to-floor distances and right popliteal angles immediately after intervention, compared with the control group (pstretching exercise group showed a significant improvement, compared with the control group (p=0.008 and 0.023). While ESWT and stretching both reduced hamstring tightness immediately after interventions, only ESWT with stretching exercise maintained the significantly improved relief of hamstring tightness significantly after 4 weeks.

  13. Experimental studies on the deformation and rupture of thin metal plates subject to underwater shock wave loading

    Directory of Open Access Journals (Sweden)

    Chen Pengwan

    2015-01-01

    Full Text Available In this paper, the dynamic deformation and rupture of thin metal plates subject to underwater shock wave loading are studied by using high-speed 3D digital image correlation (3D-DIC. An equivalent device consist of a gas gun and a water anvil tube was used to supplying an exponentially decaying pressure in lieu of explosive detonation which acted on the panel specimen. The thin metal plate is clamped on the end of the shock tube by a flange. The deformation and rupture process of the metal plates subject to underwater shock waves are recorded by two high-speed cameras. The shape, displacement fields and strain fields of the metal plates under dynamic loading are obtained by using VIC-3D digital image correlation software. The strain gauges also were used to monitor the structural response on the selected position for comparison. The DIC data and the strain gauges results show a high level of correlation, and 3D-DIC is proven to be an effective method to measure 3D full-field dynamic response of structures under underwater impact loading. The effects of pre-notches on the failure modes of thin circular plate were also discussed.

  14. Numerical simulation of solitary blood waves in an elastic tube subjected to a localised deformation

    Science.gov (United States)

    Ntchantcho, R.; Noubissie, S.; Woafo, P.

    2007-12-01

    In order to well apprehend what really happens in a locally deformed elastic tube, a numerical analysis of the liquid flow in such a media has been undertaken. A cylindrical tube with constant rigidity subjected to a localised dilatation is first considered and results obtained help to understand the behaviour and the developing process of aneurysm. The analysis of the effects of stenoses on blood flow is also done.

  15. Comparative Study on the Pulse Wave Variables and Sasang Constitution in Cerebral Infarction Patients and Healthy Subjects

    Directory of Open Access Journals (Sweden)

    Ko KiDuk

    2007-06-01

    Full Text Available This study was performed to determine whether a pulse analyzer was useful 1 to characterize the variables of pulse wave of cerebral infarction patieno (CI, compared with those of healthy subjects, as well as 2 to determine Sasang Constitution in CI and healthy subjects. 1. Calibrated in Gwan, the amount of energy(Energy, height of main peak(H1, height of aorticvalley(H2, height of aortic peak(H3, total area of pulse wave(At, and area of main peak width(Aw of the CI group were higher than those of the healthy group. 2. Calibrated in Cheek, Energy, H1, H2, H3, height of valve valley(H4, At, Aw, and main peak angle(MPA of the CI group were higher than those of the healthy group. 3. Among the healthy (subjects group, Taeumin showed the highest contact pressure(CP and height of valve peak(H5 calibrated in Chon. The main peak width divided by whole time of pulse wave(MPW/T calibrated in Gwan and Cheok, was highest in Soyangin and was lowest in Taeumin. The H3 divided by H1(H3/H1 and the time to valve valley minus the time to main peak and divided by T[(T4-T1/T] calibrated in Cheek were highest in Soyangin. The time to main peak(T1 was longest in Soumin. 4. Among the CI group, At calibrated in Chon was widest in Taeumin and was narrowest in Soumin The time to aortic peak(T3 calibrated in Cheek was longest in Soumin and was shortest in Soyangin. The time to valve peak(T5 was shortest in Soyangin. 5. There were main effects of cerebral infarction in the area of systolic period(As and area of diastolic period(Ad calibrated in Chon, Energy calibrated in Cwan, and Energy, H1, H2, H3, (H4+H5/Hl, and MPA calibrated in Cheek. 6. There were main effects of Sasang Constitution in (T4-T1/T, area of systolic period(As, and Ad calibrated in Chon. 7. The interactions between the cerebral infarction and Sasang Constitution were observed in H5/H1 , T, At, As, Ad, and MPA calibrated in Chon, H4, T4, (T4-T1/T, As, and Ad calibrated in Cwan, and 74,75, and MPW calibrated

  16. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  17. ABCA1-dependent serum cholesterol efflux capacity inversely correlates with pulse wave velocity in healthy subjects[S

    Science.gov (United States)

    Favari, Elda; Ronda, Nicoletta; Adorni, Maria Pia; Zimetti, Francesca; Salvi, Paolo; Manfredini, Matteo; Bernini, Franco; Borghi, Claudio; Cicero, Arrigo F. G.

    2013-01-01

    The capacity of HDL to induce cell cholesterol efflux is considered one of its main antiatherogenic properties. Little is known about the impact of such HDL function on vascular physiology. We investigated the relationship between ABCA1-dependent serum cholesterol efflux capacity (CEC), an HDL functionality indicator, and pulse wave velocity (PWV), an indicator of arterial stiffness. Serum of 167 healthy subjects was used to conduct CEC measurement, and carotid-femoral PWV was measured with a high-fidelity tonometer. J774 macrophages, labeled with [3H]cholesterol and stimulated to express ABCA1, were exposed to sera; the difference between cholesterol efflux from stimulated and unstimulated cells provided specific ABCA1-mediated CEC. PWV is inversely correlated with ABCA1-dependent CEC (r = −0.183; P = 0.018). Moreover, controlling for age, sex, body mass index, mean arterial pressure, serum LDL, HDL-cholesterol, and fasting plasma glucose, PWV displays a significant negative regression on ABCA1-dependent CEC (β = −0.204; 95% confidence interval, −0.371 to −0.037). The finding that ABCA1-dependent CEC, but not serum HDL cholesterol level (r = −0.002; P = 0.985), is a significant predictor of PWV in healthy subjects points to the relevance of HDL function in vascular physiology and arterial stiffness prevention. PMID:23103472

  18. Unsteady turbulence cascades.

    Science.gov (United States)

    Goto, Susumu; Vassilicos, J C

    2016-11-01

    We have run a total of 311 direct numerical simulations (DNSs) of decaying three-dimensional Navier-Stokes turbulence in a periodic box with values of the Taylor length-based Reynolds number up to about 300 and an energy spectrum with a wide wave-number range of close to -5/3 power-law dependence at the higher Reynolds numbers. On the basis of these runs, we have found a critical time when (i) the rate of change of the square of the integral length scale turns from increasing to decreasing, (ii) the ratio of interscale energy flux to high-pass filtered turbulence dissipation changes from decreasing to very slowly increasing in the inertial range, (iii) the signature of large-scale coherent structures disappears in the energy spectrum, and (iv) the scaling of the turbulence dissipation changes from the one recently discovered in DNSs of forced unsteady turbulence and in wind tunnel experiments of turbulent wakes and grid-generated turbulence to the classical scaling proposed by G. I. Taylor [Proc. R. Soc. London, Ser. A 151, 421 (1935)1364-502110.1098/rspa.1935.0158] and A. N. Kolmogorov [Dokl. Akad. Nauk SSSR 31, 538 (1941)]. Even though the customary theoretical basis for this Taylor-Kolmogorov scaling is a statistically stationary cascade where large-scale energy flux balances dissipation, this is not the case throughout the entire time range of integration in all our DNS runs. The recently discovered dissipation scaling can be reformulated physically as a situation in which the dissipation rates of the small and large scales evolve together. We advance two hypotheses that may form the basis of a theoretical approach to unsteady turbulence cascades in the presence of large-scale coherent structures.

  19. Evaluation of the optic nerve using strain and shear wave elastography in patients with multiple sclerosis and healthy subjects.

    Science.gov (United States)

    İnal, Mikail; Tan, Sinan; Yumusak, Erhan M; Şahan, Mehmet Hamdi; Alpua, Murat; Örnek, Kemal

    2017-01-31

    Our aim was to evaluate the elasticity features of the optic nerve using strain (SE) and shear wave elastography (SWE) in multiple sclerosis (MS) patients in comparison with healthy subjects. One hundred and seven optic nerves from 54 MS patients and 118 optic nerves from 59 healthy subjects were examined prospectively by SE and SWE. Optic nerves were divided into three types in accordance to the elasticity designs, as follows: type 1 predominantly blue (hardest tissue); type 2 predominantly blue/green (hard tissue); and type 3 predominantly green (intermediate tissue). Quantitative measurements of optic nerve hardness with SWE were analyzed in kilopascals. Elastographic images from healthy volunteers showed mostly type 3 optic nerves (61.9%); type 2 was also found (38.1%), but type 1 was not observed. Elastographic examination of MS patients showed mostly type 2 optic nerves (88%), while some type 1 (4.6%) and type 3 optic nerves (6.5%) were rarely observed. There was a statistically significant difference in terms of elasticity patterns between patients and healthy volunteers (p<0.001). Statistically significant differences were observed between patients and healthy volunteers in the analysis of SWE values (10.381±3.48 kPa and 33.87±11.64 p<0.001). The receiver operating characteristic curve analysis was perfect (0.993; 95% confidence interval [CI]=0.971-0.999), and a cut-off value of 18.3 kPa shear had very high sensitivity and specificity for the patient group. No significant differences were observed between patients with and without previous optic neuritis. SE and SWE examination findings concerning the optic nerve in MS patients demonstrated remarkable differences according to the healthy group.

  20. The Complexity of H-wave Amplitude Fluctuations and Their Bilateral Cross-Covariance Are Modified According to the Previous Fitness History of Young Subjects under Track Training

    Directory of Open Access Journals (Sweden)

    Maria E. Ceballos-Villegas

    2017-11-01

    Full Text Available The Hoffmann reflex (H-wave is produced by alpha-motoneuron activation in the spinal cord. A feature of this electromyography response is that it exhibits fluctuations in amplitude even during repetitive stimulation with the same intensity of current. We herein explore the hypothesis that physical training induces plastic changes in the motor system. Such changes are evaluated with the fractal dimension (FD analysis of the H-wave amplitude-fluctuations (H-wave FD and the cross-covariance (CCV between the bilateral H-wave amplitudes. The aim of this study was to compare the H-wave FD as well as the CCV before and after track training in sedentary individuals and athletes. The training modality in all subjects consisted of running three times per week (for 13 weeks in a concrete road of 5 km. Given the different physical condition of sedentary vs. athletes, the running time between sedentary and athletes was different. After training, the FD was significantly increased in sedentary individuals but significantly reduced in athletes, although there were no changes in spinal excitability in either group of subjects. Moreover, the CCV between bilateral H-waves exhibited a significant increase in athletes but not in sedentary individuals. These differential changes in the FD and CCV indicate that the plastic changes in the complexity of the H-wave amplitude fluctuations as well as the synaptic inputs to the Ia-motoneuron systems of both legs were correlated to the previous fitness history of the subjects. Furthermore, these findings demonstrate that the FD and CCV can be employed as indexes to study plastic changes in the human motor system.

  1. Terahertz Quantum Cascade Laser Based 3D Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — LongWave Photonics proposes a terahertz quantum-cascade laser based swept-source optical coherence tomography (THz SS-OCT) system for single-sided, 3D,...

  2. Next Generation Mid-Wave Infrared Cascaded Light Emitting Diodes: Growth of Broadband, Multispectral, and Single Color Devices on Gaas and Integrated Circuits

    Science.gov (United States)

    Provence, Sydney R.

    InAs/GaSb superlattices are an attractive material system for infrared light emitting diodes, due to the ability to tune the band gap throughout most of the infrared regime. A key consideration in the epitaxial growth of these heterostructures is crystalline material quality. In developing thick layers of epitaxially grown material, there are moderate amounts of elastic strain that can be incorporated into a heterostructure, beyond which deformations will form that will alleviate the lattice mismatch. This thesis investigates the optical and electronic properties of lattice-mismatched and strained materials through the study of thick dual-color light emitting diodes, broadband light emitting diodes, and InAs/GaSb superlattice devices developed on GaAs substrates and GaAs integrated circuits. A dual-color infrared light emitting diode is demonstrated emitting in the mid-wave infrared band at 3.81 mum and 4.72 mum. The design of the device stacks two independently operable InAs/GaSb superlattices structures on top of one another, so that 10 mum of material is grown with molecular beam epitaxy. Each layer is lattice-matched to a GaSb substrate. At quasi-continuous operation, radiances of 5.48 W/cm2-sr and 2.67 W/cm 2-sr are obtained. A broadband light emitting diode spanning the mid-wave infrared is demonstrated with eight stages of InAs/GaSb superlattices individually tuned to a different color. The performance of the device is compared with an identical eight stage device emitting in the middle of the mid-wave infrared. The emission of the fabricated broadband device spans from 3.2 ?m to 6 mum with peak radiance of 137.1 mW/cm2-sr. Growth of antimonide-based devices on GaAs is desirable to the relative transparency of semi-insulating substrates throughout the infrared, and as semi-insulating GaSb substrates are not available. The growth of bulk GaSb on GaAs is explored through different techniques in order to confine relaxation due to lattice mismatch strain to the

  3. Turbulence: does energy cascade exist?

    CERN Document Server

    Josserand, Christophe; Lehner, Thierry; Pomeau, Yves

    2016-01-01

    To answer the question whether a cascade of energy exists or not in turbulence, we propose a set of correlation functions able to test if there is an irreversible transfert of energy, step by step, from large to small structures. These tests are applied to real Eulerian data of a turbulent velocity flow, taken in the wind grid tunnel of Modane, and also to a prototype model equation for wave turbulence. First we demonstrate the irreversible character of the flow by using multi-time correlation function at a given point of space. Moreover the unexpected behavior of the test function leads us to connect irreversibility and finite time singularities (intermittency). Secondly we show that turbulent cascade exists, and is a dynamical process, by using a test function depending on time and frequency. The cascade shows up only in the inertial domain where the kinetic energy is transferred more rapidly (on average) from the wavenumber $k_{1}$ to $k_{2}$ than from $k_{1}$ to $k'_{2}$ larger than $k_{2}$.

  4. Variations in height of jugular "a" wave in relation to heart rate in normal subjects and in patients with atrial septal defect.

    OpenAIRE

    Thiron, J M; Cribier, A.; Cazor, J L; Letac, B

    1980-01-01

    Analysis of jugular tracings in seven normal subjects in sinus rhythm whose heart rate varied spontaneously from one moment to another during expiratory apnoea, showed that a pronounced variation occurred in the size of the "a" waves in relation to that of the "v" waves and in accordance with the corresponding RR interval. In the 53 measurements which were carried out, the "a/v" ratio had a mean value of 0.9 for a heart rate above 87, 1.4 for a heart rate between 87 and 68, and 1.1 for a hear...

  5. Nonlinear surface waves over topography

    NARCIS (Netherlands)

    Janssen, T.T.

    2006-01-01

    As ocean surface waves radiate into shallow coastal areas and onto beaches, their lengths shorten, wave heights increase, and the wave shape transforms from nearsinusoidal to the characteristic saw-tooth shapes at the onset of breaking; in the ensuing breaking process the wave energy is cascaded to

  6. Single-subject-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mild traumatic brain injury.

    Science.gov (United States)

    Huang, Ming-Xiong; Nichols, Sharon; Baker, Dewleen G; Robb, Ashley; Angeles, Annemarie; Yurgil, Kate A; Drake, Angela; Levy, Michael; Song, Tao; McLay, Robert; Theilmann, Rebecca J; Diwakar, Mithun; Risbrough, Victoria B; Ji, Zhengwei; Huang, Charles W; Chang, Douglas G; Harrington, Deborah L; Muzzatti, Laura; Canive, Jose M; Christopher Edgar, J; Chen, Yu-Han; Lee, Roland R

    2014-01-01

    Traumatic brain injury (TBI) is a leading cause of sustained impairment in military and civilian populations. However, mild TBI (mTBI) can be difficult to detect using conventional MRI or CT. Injured brain tissues in mTBI patients generate abnormal slow-waves (1-4 Hz) that can be measured and localized by resting-state magnetoencephalography (MEG). In this study, we develop a voxel-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mTBI on a single-subject basis. A normative database of resting-state MEG source magnitude images (1-4 Hz) from 79 healthy control subjects was established for all brain voxels. The high-resolution MEG source magnitude images were obtained by our recent Fast-VESTAL method. In 84 mTBI patients with persistent post-concussive symptoms (36 from blasts, and 48 from non-blast causes), our method detected abnormalities at the positive detection rates of 84.5%, 86.1%, and 83.3% for the combined (blast-induced plus with non-blast causes), blast, and non-blast mTBI groups, respectively. We found that prefrontal, posterior parietal, inferior temporal, hippocampus, and cerebella areas were particularly vulnerable to head trauma. The result also showed that MEG slow-wave generation in prefrontal areas positively correlated with personality change, trouble concentrating, affective lability, and depression symptoms. Discussion is provided regarding the neuronal mechanisms of MEG slow-wave generation due to deafferentation caused by axonal injury and/or blockages/limitations of cholinergic transmission in TBI. This study provides an effective way for using MEG slow-wave source imaging to localize affected areas and supports MEG as a tool for assisting the diagnosis of mTBI.

  7. Single-subject-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mild traumatic brain injury

    Directory of Open Access Journals (Sweden)

    Ming-Xiong Huang

    2014-01-01

    Full Text Available Traumatic brain injury (TBI is a leading cause of sustained impairment in military and civilian populations. However, mild TBI (mTBI can be difficult to detect using conventional MRI or CT. Injured brain tissues in mTBI patients generate abnormal slow-waves (1–4 Hz that can be measured and localized by resting-state magnetoencephalography (MEG. In this study, we develop a voxel-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mTBI on a single-subject basis. A normative database of resting-state MEG source magnitude images (1–4 Hz from 79 healthy control subjects was established for all brain voxels. The high-resolution MEG source magnitude images were obtained by our recent Fast-VESTAL method. In 84 mTBI patients with persistent post-concussive symptoms (36 from blasts, and 48 from non-blast causes, our method detected abnormalities at the positive detection rates of 84.5%, 86.1%, and 83.3% for the combined (blast-induced plus with non-blast causes, blast, and non-blast mTBI groups, respectively. We found that prefrontal, posterior parietal, inferior temporal, hippocampus, and cerebella areas were particularly vulnerable to head trauma. The result also showed that MEG slow-wave generation in prefrontal areas positively correlated with personality change, trouble concentrating, affective lability, and depression symptoms. Discussion is provided regarding the neuronal mechanisms of MEG slow-wave generation due to deafferentation caused by axonal injury and/or blockages/limitations of cholinergic transmission in TBI. This study provides an effective way for using MEG slow-wave source imaging to localize affected areas and supports MEG as a tool for assisting the diagnosis of mTBI.

  8. Influence of V-Diagrams on 10th Grade Turkish Students' Achievement in the Subject of Mechanical Waves

    Science.gov (United States)

    Tekes, Hanife; Gonen, Selahattin

    2012-01-01

    The purpose of the present study was to examine how the use of V-diagrams one of the learning techniques used in laboratory studies in experiments conducted regarding the 10th grade lesson unit of "waves" influenced students' achievements. In the study, a quasi-experimental design with a pretest and posttest control group was used. The…

  9. Dynamic interaction of twin vertically overlapping lined tunnels in an elastic half space subjected to incident plane waves

    Science.gov (United States)

    Liu, Zhongxian; Wang, Yirui; Liang, Jianwen

    2016-06-01

    The scattering of plane harmonic P and SV waves by a pair of vertically overlapping lined tunnels buried in an elastic half space is solved using a semi-analytic indirect boundary integration equation method. Then the effect of the distance between the two tunnels, the stiffness and density of the lining material, and the incident frequency on the seismic response of the tunnels is investigated. Numerical results demonstrate that the dynamic interaction between the twin tunnels cannot be ignored and the lower tunnel has a significant shielding effect on the upper tunnel for high-frequency incident waves, resulting in great decrease of the dynamic hoop stress in the upper tunnel; for the low-frequency incident waves, in contrast, the lower tunnel can lead to amplification effect on the upper tunnel. It also reveals that the frequency-spectrum characteristics of dynamic stress of the lower tunnel are significantly different from those of the upper tunnel. In addition, for incident P waves in low-frequency region, the soft lining tunnels have significant amplification effect on the surface displacement amplitude, which is slightly larger than that of the corresponding single tunnel.

  10. Frozen-wave instability in near-critical hydrogen subjected to horizontal vibration under various gravity fields.

    Science.gov (United States)

    Gandikota, G; Chatain, D; Amiroudine, S; Lyubimova, T; Beysens, D

    2014-01-01

    The frozen-wave instability which appears at a liquid-vapor interface when a harmonic vibration is applied in a direction tangential to it has been less studied until now. The present paper reports experiments on hydrogen (H2) in order to study this instability when the temperature is varied near its critical point for various gravity levels. Close to the critical point, a liquid-vapor density difference and surface tension can be continuously varied with temperature in a scaled, universal way. The effect of gravity on the height of the frozen waves at the interface is studied by performing the experiments in a magnetic facility where effective gravity that results from the coupling of the Earth's gravity and magnetic forces can be varied. The stability diagram of the instability is obtained. The experiments show a good agreement with an inviscid model [Fluid Dyn. 21 849 (1987)], irrespective of the gravity level. It is observed in the experiments that the height of the frozen waves varies weakly with temperature and increases with a decrease in the gravity level, according to a power law with an exponent of 0.7. It is concluded that the wave height becomes of the order of the cell size as the gravity level is asymptotically decreased to zero. The interface pattern thus appears as a bandlike pattern of alternate liquid and vapor phases, a puzzling phenomenon that was observed with CO2 and H2 near their critical point in weightlessness [Acta Astron. 61 1002 (2007); Europhys. Lett. 86 16003 (2009)].

  11. A database of virtual healthy subjects to assess the accuracy of foot-to-foot pulse wave velocities for estimation of aortic stiffness.

    Science.gov (United States)

    Willemet, Marie; Chowienczyk, Phil; Alastruey, Jordi

    2015-08-15

    While central (carotid-femoral) foot-to-foot pulse wave velocity (PWV) is considered to be the gold standard for the estimation of aortic arterial stiffness, peripheral foot-to-foot PWV (brachial-ankle, femoral-ankle, and carotid-radial) are being studied as substitutes of this central measurement. We present a novel methodology to assess theoretically these computed indexes and the hemodynamics mechanisms relating them. We created a database of 3,325 virtual healthy adult subjects using a validated one-dimensional model of the arterial hemodynamics, with cardiac and arterial parameters varied within physiological healthy ranges. For each virtual subject, foot-to-foot PWV was computed from numerical pressure waveforms at the same locations where clinical measurements are commonly taken. Our numerical results confirm clinical observations: 1) carotid-femoral PWV is a good indicator of aortic stiffness and correlates well with aortic PWV; 2) brachial-ankle PWV overestimates aortic PWV and is related to the stiffness and geometry of both elastic and muscular arteries; and 3) muscular PWV (carotid-radial, femoral-ankle) does not capture the stiffening of the aorta and should therefore not be used as a surrogate for aortic stiffness. In addition, our analysis highlights that the foot-to-foot PWV algorithm is sensitive to the presence of reflected waves in late diastole, which introduce errors in the PWV estimates. In this study, we have created a database of virtual healthy subjects, which can be used to assess theoretically the efficiency of physiological indexes based on pulse wave analysis. Copyright © 2015 the American Physiological Society.

  12. Vortex merging and spectral cascade in two-dimensional flows

    DEFF Research Database (Denmark)

    Nielsen, A.H.; He, X.; Juul Rasmussen, J.

    1996-01-01

    The merging of two identical vortices is studied numerically using a spectral code. It is noted that the enstrophy cascade is most active on the distorted vortex boundaries, with a Kolmogorov-like spectrum E(k) approximate to k(-alpha), alpha less than or equal to 4, developed at high wave numbers....... The inverse energy cascade is completed when the vortices merge into one of larger size. (C) 1996 American Institute of Physics....

  13. Active control of light based on polarization-coupling cascading

    Science.gov (United States)

    Huo, Juan; Zheng, Yuanlin; Chen, Xianfeng

    2014-10-01

    In this letter, we proposed a novel method for optical manipulation based on polarization-coupling cascading in MgO-doped periodically poled lithium niobate crystal. Polarization-coupling cascading, a series of energy exchanges between two orthogonally polarized beams close to phase matching condition, can also lead to phase shifts, in analogy with that in cascaded second-order nonlinearities. In addition, the parameters of light such as phase, amplitude, and group velocity can be modulated by changing the relative power ratio of the incident continuous wave beams. The phase control was demonstrated by Newton's rings experiment, which was in good agreement with the theoretical prediction.

  14. Sawtooth waves during REM sleep after administration of haloperidol combined with total sleep deprivation in healthy young subjects

    Directory of Open Access Journals (Sweden)

    L.R. Pinto Jr.

    2002-05-01

    Full Text Available We sought to examine the possible participation of dopaminergic receptors in the phasic events that occur during rapid eye movement (REM sleep, known as sawtooth waves (STW. These phasic phenomena of REM sleep exhibit a unique morphology and, although they represent a characteristic feature of REM sleep, little is known about the mechanisms which generate them and which are apparently different from rapid eye movements. STW behavior was studied in 10 male volunteers aged 20 to 35 years, who were submitted to polysomnographic monitoring (PSG. On the adaptation night they were submitted to the first PSG and on the second night, to the basal PSG. On the third night the volunteers received placebo or haloperidol and spent the whole night awake. On the fourth night they were submitted to the third PSG. After a 15-day rest period, the volunteers returned to the sleep laboratory and, according to a double-blind crossover randomized design, received haloperidol or placebo and spent the whole night awake, after which they were submitted to the fourth PSG. The volunteers who were given haloperidol combined with sleep deprivation exhibited an elevation of the duration and density of the STW, without significant alterations of the other REM sleep phasic phenomena such as rapid eye movement. These findings suggest that sawtooth waves must have their own generating mechanisms and that the dopaminergic receptors must exert a modulating role since REM sleep deprivation, as well as administration of neuroleptics, produces supersensitivity of dopaminergic receptors.

  15. Comparative effects of pulsed and continuous short wave diathermy on pain and selected physiological parameters among subjects with chronic knee osteoarthritis.

    Science.gov (United States)

    Teslim, Onigbinde Ayodele; Adebowale, Adenle Charles; Ojoawo, Adesola Ojo; Sunday, Odejide Akinwole; Bosede, Arilewola

    2013-01-01

    The purposes of this study were to compare the effects of pulsed and continuous short wave diathermy on pain, range of motion, pulse rate and skin temperature in subjects with chronic knee osteoarthritis. 24 Participants with grade 111 OA of the knee were randomly selected into CSWD and PSWD groups. Pre and post treatment parameters were recorded at onset and the end of 4th week. ANO VA, independent, paired t-test and chi-square were used to analyze the data. The pain experienced by participants in the CSWD group was significantly lower than that of the PSWD groups (P effective than PSWD in alleviating pain and in increasing knee flexion range of motion among subjects with chronic knee OA. Also, a mild elevation of skin temperature was able to elicit physiological effects that could exert therapeutic effects.

  16. Cascade Organic Solar Cells

    KAUST Repository

    Schlenker, Cody W.

    2011-09-27

    We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

  17. Complementary numerical–experimental benchmarking for shape optimization and validation of structures subjected to wave and current forces

    DEFF Research Database (Denmark)

    Markus, D.; Ferri, Francesco; Wüchner, R.

    2015-01-01

    A new benchmark problem is proposed and evaluated targeting fluid related shape optimization problems, motivated by design related ocean engineering tasks. The analyzed test geometry is a bottom mounted, polygonal structure in a channel flow. The aim of the study is to analyze the effect of shape...... is to provide clear and thorough information for validation and verification of methods and codes used to analyze fluid related shape optimization problems....... variations of the structure on the resulting horizontal forces. Steady current conditions, dynamic loading due to waves, and combined wave–current scenarios are considered. A clear focus is put on simplicity and reproducibility, allowing for efficient testing of related methods and codes. This is achieved...

  18. Shallow Water Waves and Solitary Waves

    OpenAIRE

    Hereman, Willy

    2013-01-01

    Encyclopedic article covering shallow water wave models used in oceanography and atmospheric science. Sections: Definition of the Subject; Introduction and Historical Perspective; Completely Integrable Shallow Water Wave Equations; Shallow Water Wave Equations of Geophysical Fluid Dynamics; Computation of Solitary Wave Solutions; Numerical Methods; Water Wave Experiments and Observations; Future Directions, and Bibliography.

  19. Electron-ion temperature ratio estimations in the summer polar mesosphere when subject to HF radio wave heating

    Science.gov (United States)

    Pinedo, H.; La Hoz, C.; Havnes, O.; Rietveld, M.

    2014-10-01

    We have inferred the electron temperature enhancements above mesospheric altitudes under Polar Mesospheric Summer Echoes (PMSE) conditions when the ionosphere is exposed to artificial HF radio wave heating. The proposed method uses the dependence of the radar cross section on the electron-to-ion temperature ratio to infer the heating factor from incoherent scatter radar (ISR) power measurements above 90 km. Model heating temperatures match our ISR estimations between 90 and 130 km with 0.94 Pearson correlation index. The PMSE strength measured by the MORRO MST radar is about 50% weaker during the heater-on period when the modeled electron-to-ion mesospheric temperature is approximately 10 times greater than the unperturbed value. No PMSE weakening is found when the mesospheric temperature enhancement is by a factor of three or less. The PMSE weakening and its absence are consistent with the modeled mesospheric electron temperatures. This consistency supports to the proposed method for estimating mesospheric electron temperatures achieved by independent MST and ISR radar measurements.

  20. Howling about Trophic Cascades

    Science.gov (United States)

    Kowalewski, David

    2012-01-01

    Following evolutionary theory and an agriculture model, ecosystem research has stressed bottom-up dynamics, implying that top wild predators are epiphenomenal effects of more basic causes. As such, they are assumed expendable. A more modern co-evolutionary and wilderness approach--trophic cascades--instead suggests that top predators, whose…

  1. Extracorporeal shock wave therapy in patients with plantar fasciitis. A randomized, placebo-controlled trial with ultrasonographic and subjective outcome assessments

    Directory of Open Access Journals (Sweden)

    Babak Vahdatpour

    2012-01-01

    Full Text Available Background and Aim: Results of previous studies have been conflicting on the efficacy of extracorporeal shock wave therapy (ESWT in the treatment of plantar fasciitis. We evaluated the effects of ESWT on plantar fasciitis in terms of ultrasonographic and subjective evaluations. Materials and Methods: In this randomized placebo-controlled trial, patients with plantar fasciitis were assigned to receive ESWT (4000 shock waves/session of 0.2 mJ/mm 2 in 3 sessions at weekly intervals or sham therapy (n = 20 in each group. Outcomes were documented by the ultrasonographic appearance of the aponeurosis and by patients′ pain scores, performed at baseline and 12 weeks after completion of the therapy. Results : The two groups were similar in baseline characteristics. Over the study period, plantar fascia thickness significantly reduced in the ESWT group (4.1 ± 1.3 to 3.6 ± 1.2 mm, P < 0.001, but slightly increased in the sham group (4.1 ± 0.8 to 4.5 ± 0.9 mm, P = 0.03. Both groups showed significant pain improvement over the course of the study (P < 0.001, though pain scores were significantly more reduced in the ESWT than the sham group (-4.2 ± 2.9 vs. -2.7 ± 1.8, P = 0.049. Conclusions: Extracorporeal shock wave therapy contributes to healing and pain reduction in plantar fasciitis and ultrasound imaging is able to depict the morphologic changes related to plantar fasciitis as a result of this therapy.

  2. Phase synchronization of baroclinic waves in a differentially heated rotating annulus experiment subject to periodic forcing with a variable duty cycle

    Science.gov (United States)

    Read, P. L.; Morice-Atkinson, X.; Allen, E. J.; Castrejón-Pita, A. A.

    2017-12-01

    A series of laboratory experiments in a thermally driven, rotating fluid annulus are presented that investigate the onset and characteristics of phase synchronization and frequency entrainment between the intrinsic, chaotic, oscillatory amplitude modulation of travelling baroclinic waves and a periodic modulation of the (axisymmetric) thermal boundary conditions, subject to time-dependent coupling. The time-dependence is in the form of a prescribed duty cycle in which the periodic forcing of the boundary conditions is applied for only a fraction δ of each oscillation. For the rest of the oscillation, the boundary conditions are held fixed. Two profiles of forcing were investigated that capture different parts of the sinusoidal variation and δ was varied over the range 0.1 ≤δ≤1 . Reducing δ was found to act in a similar way to a reduction in a constant coupling coefficient in reducing the width of the interval in forcing frequency or period over which complete synchronization was observed (the "Arnol'd tongue") with respect to the detuning, although for the strongest pulse-like forcing profile some degree of synchronization was discernible even at δ=0.1 . Complete phase synchronization was obtained within the Arnol'd tongue itself, although the strength of the amplitude modulation of the baroclinic wave was not significantly affected. These experiments demonstrate a possible mechanism for intraseasonal and/or interannual "teleconnections" within the climate system of the Earth and other planets that does not rely on Rossby wave propagation across the planet along great circles.

  3. Extracorporeal shock wave therapy in patients with plantar fasciitis. A randomized, placebo-controlled trial with ultrasonographic and subjective outcome assessments

    Science.gov (United States)

    Vahdatpour, Babak; Sajadieh, Sepideh; Bateni, Vahid; Karami, Mehdi; Sajjadieh, Hamidreza

    2012-01-01

    Background and Aim: Results of previous studies have been conflicting on the efficacy of extracorporeal shock wave therapy (ESWT) in the treatment of plantar fasciitis. We evaluated the effects of ESWT on plantar fasciitis in terms of ultrasonographic and subjective evaluations. Materials and Methods: In this randomized placebo-controlled trial, patients with plantar fasciitis were assigned to receive ESWT (4000 shock waves/session of 0.2 mJ/mm2) in 3 sessions at weekly intervals) or sham therapy (n = 20 in each group). Outcomes were documented by the ultrasonographic appearance of the aponeurosis and by patients’ pain scores, performed at baseline and 12 weeks after completion of the therapy. Results: The two groups were similar in baseline characteristics. Over the study period, plantar fascia thickness significantly reduced in the ESWT group (4.1 ± 1.3 to 3.6 ± 1.2 mm, P plantar fasciitis and ultrasound imaging is able to depict the morphologic changes related to plantar fasciitis as a result of this therapy. PMID:23826009

  4. Relationship Between Subjective Preference and the Alpha-Brain Wave in Relation to the Initial Time Delay Gap with Vocal Music

    Science.gov (United States)

    MOURI, K.; AKIYAMA, K.; ANDO, Y.

    2000-04-01

    Previously, it was reported that the most preferred initial time delay gap [Δt1]pand subsequent reverberation time are described by the minimum value of the effective duration (τe)minof the running autocorrelation function (ACF) of music signals (2 T=2·0 s) (Y. ANDO et al. 1989 Journal of Acoustical Society of America86, 644-649). This paper shows whether this result is supported or not by use of the electro-physiological method. Experiments were performed for sound fields changing the initial time delay gapΔt1 of a single reflection with vocal music as a source signal, which has large changes in runningτe . The results at the time interval when (τe)minof the music is observed reveal that the scale value of subjective preference is closely related to the value of τeof the alpha wave obtained from the left heimsphere.

  5. Time scales and structures of wave interaction exemplified with water waves

    Science.gov (United States)

    Kartashova, Elena

    2013-05-01

    Presently two models for computing energy spectra in weakly nonlinear dispersive media are known: kinetic wave turbulence theory, using a statistical description of an energy cascade over a continuous spectrum (K-cascade), and the D-model, describing resonant clusters and energy cascades (D-cascade) in a deterministic way as interaction of distinct modes. In this letter we give an overview of these structures and their properties and a list of criteria about which model of energy cascade should be used in the analysis of a given experiment, using water waves as an example. Applying the time scale analysis to weakly nonlinear wave systems modeled by the focusing nonlinear Schödinger equation, we demonstrate that K-cascade and D-cascade are not competing processes but rather two processes taking place at different time scales, at different characteristic levels of nonlinearity and based on different physical mechanisms. Applying those criteria to data known from experiments with surface water waves we find that the energy cascades observed occur at short characteristic times compatible only with a D-cascade. The only pre-requisite for a D-cascade being a focusing nonlinear Schödinger equation, the same analysis may be applied to existing experiments with wave systems appearing in hydrodynamics, nonlinear optics, electrodynamics, plasma, convection theory, etc.

  6. Simultaneous versus Sequential Accelerated Corneal Collagen Cross-Linking and Wave Front Guided PRK for Treatment of Keratoconus: Objective and Subjective Evaluation

    Directory of Open Access Journals (Sweden)

    Waleed Ali Abou Samra

    2016-01-01

    Full Text Available Aim. To compare objective and subjective outcome after simultaneous wave front guided (WFG PRK and accelerated corneal cross-linking (CXL in patients with progressive keratoconus versus sequential WFG PRK 6 months after CXL. Methods. 62 eyes with progressive keratoconus were divided into two groups; the first including 30 eyes underwent simultaneous WFG PRK with accelerated CXL. The second including 32 eyes underwent subsequent WFG PRK performed 6 months later after accelerated CXL. Visual, refractive, topographic, and aberrometric data were determined preoperatively and during 1-year follow-up period and the results compared in between the 2 studied groups. Results. All evaluated visual, refractive, and aberrometric parameters demonstrated highly significant improvement in both studied groups (all P<0.001. A significant improvement was observed in keratometric and Q values. The improvement in all parameters was stable till the end of follow-up. Likewise, no significant difference was determined in between the 2 groups in any of recorded parameters. Subjective data revealed similarly significant improvement in both groups. Conclusions. WFG PRK and accelerated CXL is an effective and safe option to improve the vision in mild to moderate keratoconus. In one-year follow-up, there is no statistically significant difference between the simultaneous and sequential procedure.

  7. Optical Cherenkov radiation in ultrafast cascaded second-harmonic generation

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Zhou, Binbin

    2010-01-01

    We show through theory and numerics that when few-cycle femtosecond solitons are generated through cascaded (phase-mismatched) second-harmonic generation, these broadband solitons can emit optical Cherenkov radiation in the form of linear dispersive waves located in the red part of the spectrum. ...

  8. Polymorphisms of COL4A1 gene are associated with arterial pulse wave velocity in healthy Han Chinese and Uygur subjects

    Science.gov (United States)

    Adi, Dilare; Xie, Xiang; Xiang, Yang; Ma, Yi-Tong; Yang, Yi-Ning; Fu, Zhen-Yan; Li, Xiao-Mei; Liu, Fen; Chen, Bang-Dang

    2015-01-01

    Pulse wave velocity (PWV) is a noninvasive index of arterial stiffness and an independent predictor of cardiovascular outcomes. Type IV collagen is an important structural component of the vascular basement membrane, thus it is important for the integrity and functions of basement membrane. However, the relationship between genetic polymorphisms of COL4A1 gene and PWV in healthy Han Chinese and Uygur subjects remains unclear. We aimed to investigate the association between PWV and COL4A1 genetic polymorphisms in healthy Han Chinese and Uygur subjects. A total of 1533 subjects (909 Han, 624 Uygur) were selected from the Cardiovascular Risk Survey (CRS) study. Two SNPs (rs605143 and rs565470) were genotyped by using the polymerase chain reaction-restriction fragment length (PCR-RFLP) method. In the Uygur population, the two SNPs (rs605143 and rs565470) were associated with PWV by analyses of a recessive model (p = 0.002, p = 0.008, respectively), and the difference remained significant after multivariate adjustment (p = 0.004, p = 0.001, respectively); the AA genotype of rs605143 was associated with increased PWV value compared with the AG or GG genotype (1543.36 ± 324.79 cm/s vs. 1530.45 ± 314.24 cm/s and 1522.93 ± 316.00 cm/s); and the CC genotype of rs565470 was associated with increased PWV value compared with the CT or TT genotype (1647.90 ± 553.27 cm/s vs. 1506.8 ± 357.35 cm/s and 1488.4 ± 344.32 cm/s). But for healthy Han Chinese subjects, this association was not observed in rs605143 and rs565470 before and after multivariate adjustment. Both rs605143 and rs565470 in the COL4A1 gene are associated with PWV in healthy Uygur subjects, indicating that carriers of the A allele of rs605143 and the C allele of rs565470 have a high risk of Arterial stiffness. PMID:25932222

  9. Inverse cascades sustained by the transfer rate of angular momentum in a 3D turbulent flow.

    Science.gov (United States)

    López-Caballero, Miguel; Burguete, Javier

    2013-03-22

    The existence of energy cascades as signatures of conserved magnitudes is one of the universal characteristics of turbulent flows. In homogeneous 3D turbulence, the energy conservation produces a direct cascade from large to small scales, although in 2D, it produces an inverse cascade pointing towards small wave numbers. In this Letter, we present the first evidence of an inverse cascade in a fully developed 3D experimental turbulent flow where the conserved magnitude is the angular momentum. Two counterrotating flows collide in a central region where very large fluctuations are produced, generating a turbulent drag that transfers the external torque between different fluid layers.

  10. Evolution of the reflection and focusing patterns and stress states in two-fluid cylindrical shell systems subjected to an external shock wave

    Science.gov (United States)

    Iakovlev, S.; Dooley, G.; Williston, K.; Gaudet, J.

    2011-12-01

    Several most important features of the hydrodynamic field induced inside a circular cylindrical shell filled with and submerged into different fluids when it is subjected to an external shock wave are considered. This investigation is a follow-up of an earlier study of the two-fluid shell-shock interaction [S. Iakovlev, Interaction between an external shock wave and a cylindrical shell filled with and submerged into different fluids, Journal of Sound and Vibration 322 (2009) 401-437], and it addresses a number of practically important issues not covered in that work. The focus of this study is on the evolution of the respective hydrodynamic patterns in response to the continuous change of the parameters of the fluids, in particular the speed of sound. Along with the analysis of the hydrodynamic patterns it is also demonstrated that when one is concerned with the highest pressure attained inside the shell, the most dangerous combination of the parameters occurs when the ratio of the internal and external acoustic speeds is close to 0.48, with the respective pressure exceeding the maximum incident pressure by more than 110 percent. The effect that the hydrodynamic features discussed have on the stress state of the shell is addressed as well, and it is observed that the maximum tensile stress is significantly affected by the evolution of the considered hydrodynamic features, whereas the maximum compressive stress is not. It is also observed that the maximum tensile stress is very sensitive to the change of the ratio of the acoustic speeds in the internal and external fluids, with as little an increase of the latter as 13 percent resulting in more than doubling of the former in some cases.

  11. Fractal Levy correlation cascades

    Energy Technology Data Exchange (ETDEWEB)

    Eliazar, Iddo [Department of Technology Management, Holon Institute of Technology, Holon 58102 (Israel); Klafter, Joseph [School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

    2007-04-20

    The correlation structure of a wide class of random processes, driven by stable non-Gaussian Levy noise sources, is explored. Since these noises are of infinite variance, correlations cannot be measured via auto-covariance functions. Exploiting the underlying Poissonian structure of Levy noises, we present a cascade of 'Poissonian correlation functions' which characterize the correlation structure and the process distribution of the processes under consideration. The theory developed is applied to various examples including motions, Ornstein-Uhlenbeck and moving-average processes, and fractional motions and noises-all driven by stable non-Gaussian Levy noises. (fast track communication)

  12. Cascading Corruption News

    DEFF Research Database (Denmark)

    Damgaard, Mads

    2018-01-01

    Through a content analysis of 8,800 news items and six months of front pages in three Brazilian newspapers, all dealing with corruption and political transgression, this article documents the remarkable skew of media attention to corruption scandals. The bias is examined as an information...... phenomenon, arising from systemic and commercial factors of Brazil’s news media: An information cascade of news on corruption formed, destabilizing the governing coalition and legitimizing the impeachment process of Dilma Rousseff. As this process gained momentum, questions of accountability were disregarded...

  13. Quantum Cascade Lasers Modulation and Applications

    Science.gov (United States)

    Luzhansky, Edward

    The mid-wave IR (MWIR) spectral band, extending from 3 to 5 microns, is considered to be a low loss atmospheric window. There are several spectral sub-bands with relatively low atmospheric attenuation in this region making it popular for various commercial and military applications. Relatively low thermal and solar background emissions, effective penetration through the natural and anthropogenic obscurants and eye safety add to the long list of advantages of MWIR wavelengths. Quantum Cascade Lasers are compact semiconductor devices capable of operating in MWIR spectrum. They are based on inter-subband transitions in a multiple-quantum-well (QW) hetero-structure, designed by means of band-structure engineering. The inter-subband nature of the optical transition has several key advantages. First, the emission wavelength is primarily a function of the QW thickness. This characteristic allows choosing well-understood and reliable semiconductors for the generation of light in a wavelength range of interest. Second, a cascade process in which tens of photons are generated per injected electron. This cascading process is behind the intrinsic high-power capabilities of QCLs. This dissertation is focused on modulation properties of Quantum Cascade Lasers. Both amplitude and phase/frequency modulations were studied including modulation bandwidth, modulation efficiency and chirp linearity. Research was consisted of the two major parts. In the first part we describe the theory of frequency modulation (FM) response of Distributed Feedback Quantum Cascade Lasers (DFB QCL). It includes cascading effect on the QCL's maximum modulation frequency. The "gain levering" effect for the maximum FM response of the two section QCLs was studied as well. In the second part of research we concentrated on the Pulse Position Amplitude Modulation of a single section QCL. The low complexity, low size, weight and power Mid-Wavelength Infra-Red optical communications transceiver concept is

  14. Cascaded impedance networks for NPC inverter

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang

    2010-01-01

    Multilevel inverters are getting more and more attracted because they have better output waveform quality and lower semiconductor voltage stress. The Z-source NPC is a kind of single stage multilevel inverter which has the ability of voltage boost. But the boost capability is relatively low when...... they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...... would have a higher output voltage gain. It is anticipated that it would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually requested. Experimental testing has already been conducted and verifies the theory....

  15. On the turbulent energy cascade in anisotropic magnetohydrodynamic turbulence

    CERN Document Server

    Carbone, V; Marino, R

    2010-01-01

    The problem of the occurrence of an energy cascade for Alfv\\'enic turbulence in solar wind plasmas was hystorically addressed by using phenomenological arguments based to the weakness of nonlinear interactions and the anisotropy of the cascade in wave vectors space. Here, this paradox is reviewed through the formal derivation of a Yaglom relation from anisotropic Magnetohydrodynamic equation. The Yaglom relation involves a third-order moment calculated from velocity and magnetic fields and involving both Els\\"asser vector fields, and is particularly useful to be used as far as spacecraft observations of turbulence are concerned.

  16. Cascade Distillation System Development

    Science.gov (United States)

    Callahan, Michael R.; Sargushingh, Miriam; Shull, Sarah

    2014-01-01

    NASA's Advanced Exploration Systems (AES) Life Support System (LSS) Project is chartered with de-veloping advanced life support systems that will ena-ble NASA human exploration beyond low Earth orbit (LEO). The goal of AES is to increase the affordabil-ity of long-duration life support missions, and to re-duce the risk associated with integrating and infusing new enabling technologies required to ensure mission success. Because of the robust nature of distillation systems, the AES LSS Project is pursuing develop-ment of the Cascade Distillation Subsystem (CDS) as part of its technology portfolio. Currently, the system is being developed into a flight forward Generation 2.0 design.

  17. Progress in high-performance quantum cascade lasers

    Science.gov (United States)

    Lyakh, Arkadiy; Maulini, Richard; Tsekoun, Alexei G.; Patel, C. Kumar N.

    2010-11-01

    Because of their compact size, reliability, tunability, and convenience of direct electrical pumping, quantum cascade lasers have found a number of important civilian and defense applications in the midwave infrared and long-wave-infrared spectral range. Most of these applications would benefit from higher laser optical power and higher wall-plug efficiency. We describe some of the most important features of high-efficiency quantum cascade laser design and realization of high-power quantum cascade laser systems. Specifically, optimization of the active region and waveguide, thermal management on the chip level, and impact of the laser facet coating on laser efficiency and scaling of optical power with cavity length are discussed. Also, we present experimental results demonstrating multiwatt operation with reliability of at least several thousands of hours on a system level.

  18. Analysis of cascading failure in gene networks

    Directory of Open Access Journals (Sweden)

    Shudong eWang

    2012-12-01

    Full Text Available It is an important subject to research the functional mechanism of cancer-related genes make in formation and development of cancers. The modern methodology of data analysis plays a very important role for deducing the relationship between cancers and cancer-related genes and analyzing functional mechanism of genome. In this research, we construct mutual information networks using gene expression profiles of glioblast and renal in normal condition and cancer conditions. We investigate the relationship between structure and robustness in gene networks of the two tissues using a cascading failure model based on betweenness centrality. Define some important parameters such as the percentage of failure nodes of the network, the average size-ratio of cascading failure and the cumulative probability of size-ratio of cascading failure to measure the robustness of the networks. By comparing control group and experiment groups, we find that the networks of experiment groups are more robust than that of control group. The gene that can cause large scale failure is called structural key gene (SKG. Some of them have been confirmed to be closely related to the formation and development of glioma and renal cancer respectively. Most of them are predicted to play important roles during the formation of glioma and renal cancer, maybe the oncogenes, suppressor genes, and other cancer candidate genes in the glioma and renal cancer cells. However, these studies provide little information about the detailed roles of identified cancer genes.

  19. Inferring network structure from cascades

    Science.gov (United States)

    Ghonge, Sushrut; Vural, Dervis Can

    2017-07-01

    Many physical, biological, and social phenomena can be described by cascades taking place on a network. Often, the activity can be empirically observed, but not the underlying network of interactions. In this paper we offer three topological methods to infer the structure of any directed network given a set of cascade arrival times. Our formulas hold for a very general class of models where the activation probability of a node is a generic function of its degree and the number of its active neighbors. We report high success rates for synthetic and real networks, for several different cascade models.

  20. Cascade Mountain Range in Oregon

    Science.gov (United States)

    Sherrod, David R.

    2016-01-01

    The Cascade mountain system extends from northern California to central British Columbia. In Oregon, it comprises the Cascade Range, which is 260 miles long and, at greatest breadth, 90 miles wide (fig. 1). Oregon’s Cascade Range covers roughly 17,000 square miles, or about 17 percent of the state, an area larger than each of the smallest nine of the fifty United States. The range is bounded on the east by U.S. Highways 97 and 197. On the west it reaches nearly to Interstate 5, forming the eastern margin of the Willamette Valley and, farther south, abutting the Coast Ranges. 

  1. Emergence of a turbulent cascade in a quantum gas

    Science.gov (United States)

    Navon, Nir; Gaunt, Alexander L.; Smith, Robert P.; Hadzibabic, Zoran

    2016-11-01

    A central concept in the modern understanding of turbulence is the existence of cascades of excitations from large to small length scales, or vice versa. This concept was introduced in 1941 by Kolmogorov and Obukhov, and such cascades have since been observed in various systems, including interplanetary plasmas, supernovae, ocean waves and financial markets. Despite much progress, a quantitative understanding of turbulence remains a challenge, owing to the interplay between many length scales that makes theoretical simulations of realistic experimental conditions difficult. Here we observe the emergence of a turbulent cascade in a weakly interacting homogeneous Bose gas—a quantum fluid that can be theoretically described on all relevant length scales. We prepare a Bose-Einstein condensate in an optical box, drive it out of equilibrium with an oscillating force that pumps energy into the system at the largest length scale, study its nonlinear response to the periodic drive, and observe a gradual development of a cascade characterized by an isotropic power-law distribution in momentum space. We numerically model our experiments using the Gross-Pitaevskii equation and find excellent agreement with the measurements. Our experiments establish the uniform Bose gas as a promising new medium for investigating many aspects of turbulence, including the interplay between vortex and wave turbulence, and the relative importance of quantum and classical effects.

  2. Cascading effects following intervention.

    Science.gov (United States)

    Patterson, Gerald R; Forgatch, Marion S; Degarmo, David S

    2010-11-01

    Four different sources for cascade effects were examined using 9-year process and outcome data from a randomized controlled trial of a preventive intervention using the Parent Management Training-Oregon Model (PMTO™). The social interaction learning model of child antisocial behavior serves as one basis for predicting change. A second source addresses the issue of comorbid relationships among clinical diagnoses. The third source, collateral changes, describes events in which changes in one family member correlate with changes in another. The fourth component is based on the long-term effects of reducing coercion and increasing positive interpersonal processes within the family. New findings from the 9-year follow-up show that mothers experienced benefits as measured by standard of living (i.e., income, occupation, education, and financial stress) and frequency of police arrests. It is assumed that PMTO reduces the level of coercion, which sets the stage for a massive increase in positive social interaction. In effect, PMTO alters the family environment and thereby opens doors to healthy new social environments.

  3. Injectorless quantum cascade lasers

    Science.gov (United States)

    Katz, Simeon; Vizbaras, Augustinas; Meyer, Ralf; Amann, Markus-Christian

    2011-04-01

    This review focuses on recent progress on injectorless quantum cascade lasers, an increasingly attractive approach in comparison to the "classical" injectorbased concepts. This particularly holds for the wavelength range between 7 and 12 μm, where fundamental vibrational modes of many important molecules exist, so that sensor systems for medical, industrial and military applications highly benefit from these laser sources. The atmospheric transmission window between 8 and 12 μm, with very low damping, also enables free space applications like communication, military countermeasures, and environmental sensors. Injectorless devices operate closer to the original design principle for intersubband lasers as suggested by Suris and Kazarinov [Sov. Phys. Semicond. 5, 707 (1971)]. Therefore, a short description of their features is given in comparison to injectorbased devices. Within recent years, injectorless devices have seen rapid improvement in performance. Best injectorless devices reach threshold current densities of 450 A/cm2 at 300 K, a factor of 1.6 smaller than that for the best injectorbased devices. Their output efficiency has also increased from 2% to more than 7% within the last 2 years, reaching comparable levels and making the injectorless device concept competitive and very attractive for applications.

  4. Deep-cascade: Cascading 3D Deep Neural Networks for Fast Anomaly Detection and Localization in Crowded Scenes.

    Science.gov (United States)

    Sabokrou, Mohammad; Fayyaz, Mohsen; Fathy, Mahmood; Klette, Reinhard

    2017-02-17

    This paper proposes a fast and reliable method for anomaly detection and localization in video data showing crowded scenes. Time-efficient anomaly localization is an ongoing challenge and subject of this paper. We propose a cubicpatch- based method, characterised by a cascade of classifiers, which makes use of an advanced feature-learning approach. Our cascade of classifiers has two main stages. First, a light but deep 3D auto-encoder is used for early identification of "many" normal cubic patches. This deep network operates on small cubic patches as being the first stage, before carefully resizing remaining candidates of interest, and evaluating those at the second stage using a more complex and deeper 3D convolutional neural network (CNN). We divide the deep autoencoder and the CNN into multiple sub-stages which operate as cascaded classifiers. Shallow layers of the cascaded deep networks (designed as Gaussian classifiers, acting as weak single-class classifiers) detect "simple" normal patches such as background patches, and more complex normal patches are detected at deeper layers. It is shown that the proposed novel technique (a cascade of two cascaded classifiers) performs comparable to current top-performing detection and localization methods on standard benchmarks, but outperforms those in general with respect to required computation time.

  5. Cascade dynamics on complex networks.

    OpenAIRE

    Hackett, Adam W.

    2011-01-01

    peer-reviewed The network topologies on which many natural and synthetic systems are built provide ideal settings for the emergence of complex phenomena. One well-studied manifestation of this, called a cascade or avalanche, is observed when interactions between the components of a system allow an initially localized effect to propagate globally. For example, the malfunction of technological systems like email networks or electrical power grids is often attributable to a cascade o...

  6. Long-term reliability study and failure analysis of quantum cascade lasers

    Science.gov (United States)

    Xie, Feng; Nguyen, Hong-Ky; Leblanc, Herve; Hughes, Larry; Wang, Jie; Miller, Dean J.; Lascola, Kevin

    2017-02-01

    Here we present lifetime test results of 4 groups of quantum cascade lasers (QCL) under various aging conditions including an accelerated life test. The total accumulated life time exceeds 1.5 million device·hours, which is the largest QCL reliability study ever reported. The longest single device aging time was 46.5 thousand hours (without failure) in the room temperature test. Four failures were found in a group of 19 devices subjected to the accelerated life test with a heat-sink temperature of 60 °C and a continuous-wave current of 1 A. Visual inspection of the laser facets of failed devices revealed an astonishing phenomenon, which has never been reported before, which manifested as a dark belt of an unknown substance appearing on facets. Although initially assumed to be contamination from the environment, failure analysis revealed that the dark substance is a thermally induced oxide of InP in the buried heterostructure semiinsulating layer. When the oxidized material starts to cover the core and blocks the light emission, it begins to cause the failure of QCLs in the accelerated test. An activation energy of 1.2 eV is derived from the dependence of the failure rate on laser core temperature. With the activation energy, the mean time to failure of the quantum cascade lasers operating at a current density of 5 kA/cm2 and heat-sink temperature of 25°C is expected to be 809 thousand hours.

  7. Interband Cascade Photovoltaic Cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui Q. [Univ. of Oklahoma, Norman, OK (United States); Santos, Michael B. [Univ. of Oklahoma, Norman, OK (United States); Johnson, Matthew B. [Univ. of Oklahoma, Norman, OK (United States)

    2014-09-24

    In this project, we are performing basic and applied research to systematically investigate our newly proposed interband cascade (IC) photovoltaic (PV) cells [1]. These cells follow from the great success of infrared IC lasers [2-3] that pioneered the use of quantum-engineered IC structures. This quantum-engineered approach will enable PV cells to efficiently convert infrared radiation from the sun or other heat source, to electricity. Such cells will have important applications for more efficient use of solar energy, waste-heat recovery, and power beaming in combination with mid-infrared lasers. The objectives of our investigations are to: achieve extensive understanding of the fundamental aspects of the proposed PV structures, develop the necessary knowledge for making such IC PV cells, and demonstrate prototype working PV cells. This research will focus on IC PV structures and their segments for utilizing infrared radiation with wavelengths from 2 to 5 μm, a range well suited for emission by heat sources (1,000-2,000 K) that are widely available from combustion systems. The long-term goal of this project is to push PV technology to longer wavelengths, allowing for relatively low-temperature thermal sources. Our investigations address material quality, electrical and optical properties, and their interplay for the different regions of an IC PV structure. The tasks involve: design, modeling and optimization of IC PV structures, molecular beam epitaxial growth of PV structures and relevant segments, material characterization, prototype device fabrication and testing. At the end of this program, we expect to generate new cutting-edge knowledge in the design and understanding of quantum-engineered semiconductor structures, and demonstrate the concepts for IC PV devices with high conversion efficiencies.

  8. Inverse cascades and resonant triads in rotating and stratified turbulence

    Science.gov (United States)

    Oks, D.; Mininni, P. D.; Marino, R.; Pouquet, A.

    2017-11-01

    Kraichnan's seminal ideas on inverse cascades yielded new tools to study common phenomena in geophysical turbulent flows. In the atmosphere and the oceans, rotation and stratification result in a flow that can be approximated as two-dimensional at very large scales but which requires considering three-dimensional effects to fully describe turbulent transport processes and non-linear phenomena. Motions can thus be classified into two classes: fast modes consisting of inertia-gravity waves and slow quasi-geostrophic modes for which the Coriolis force and horizontal pressure gradients are close to balance. In this paper, we review previous results on the strength of the inverse cascade in rotating and stratified flows and then present new results on the effect of varying the strength of rotation and stratification (measured by the inverse Prandtl ratio N/f, of the Coriolis frequency to the Brunt-Väisäla frequency) on the amplitude of the waves and on the flow quasi-geostrophic behavior. We show that the inverse cascade is more efficient in the range of N/f for which resonant triads do not exist, 1 /2 ≤N /f ≤2 . We then use the spatio-temporal spectrum to show that in this range slow modes dominate the dynamics, while the strength of the waves (and their relevance in the flow dynamics) is weaker.

  9. The Cascade of Non-Stationarity

    Science.gov (United States)

    Belmont, P.; Kumarasamy, K.; Kelly, S. A.; Schaffrath, K. R.; Beach, T. J.

    2014-12-01

    Landscapes and channel networks are dynamic systems, often characterized by immense variability in time and space. Systematic shifts in hydrologic, geomorphic, or ecologic drivers can cause a cascade of changes within the system, which may fundamentally alter the way the system itself functions. Due to variability in resilience and resisting forces throughout the landscape, this cascade of changes may manifest in different ways within any given system. Humans may also exert considerable influence, often amplifying or damping system response. We illustrate the cascading effects of non-stationary hydrology and geomorphology in the Minnesota River Basin (MRB), a 44,000 km2 natural laboratory in which pervasive landscape disturbance has been triggered by several well-documented events. Rapid base-level lowering 13,400 YBP along the mainstem Minnesota River created a wave of incision, which continues to propagate up tributary channel networks. Temperature and precipitation have changed significantly in the MRB over the past century with rising temperatures, shifting precipitation patterns and an increase in heavy rainfall events. Streamflow has changed drastically and variably throughout the basin with 5% exceedance flows increasing 60-100% in recent decades, as increases in precipitation have been amplified by land management and artificial drainage. Increases in channel width and depth have occurred variably in the mainstem Minnesota River, the actively incising lower (knick zone) reaches of tributaries, and the low gradient, passively meandering reaches above the knick zones. Altered hydrologic regimes and channel morphologies, combined with increased sedimentation and nutrient loading have adversely affected aquatic biota via disruption of life cycles and habitat degradation. Existing landscape, water quality, and flood risk models are poorly equipped to deal with the cascading effects of non-stationarity and therefore may grossly over- or under

  10. Cascaded failures in weighted networks

    Science.gov (United States)

    Mirzasoleiman, Baharan; Babaei, Mahmoudreza; Jalili, Mahdi; Safari, Mohammadali

    2011-10-01

    Many technological networks can experience random and/or systematic failures in their components. More destructive situations can happen if the components have limited capacity, where the failure in one of them might lead to a cascade of failures in other components, and consequently break down the structure of the network. In this paper, the tolerance of cascaded failures was investigated in weighted networks. Three weighting strategies were considered including the betweenness centrality of the edges, the product of the degrees of the end nodes, and the product of their betweenness centralities. Then, the effect of the cascaded attack was investigated by considering the local weighted flow redistribution rule. The capacity of the edges was considered to be proportional to their initial weight distribution. The size of the survived part of the attacked network was determined in model networks as well as in a number of real-world networks including the power grid, the internet in the level of autonomous system, the railway network of Europe, and the United States airports network. We found that the networks in which the weight of each edge is the multiplication of the betweenness centrality of the end nodes had the best robustness against cascaded failures. In other words, the case where the load of the links is considered to be the product of the betweenness centrality of the end nodes is favored for the robustness of the network against cascaded failures.

  11. Relations between depressive symptoms, anxiety, and T Wave abnormalities in subjects without clinically-apparent cardiovascular disease (from the Multi-Ethnic Study of Atherosclerosis [MESA]).

    Science.gov (United States)

    Whang, William; Peacock, James; Soliman, Elsayed Z; Alcantara, Carmela; Nazarian, Saman; Shah, Amit J; Davidson, Karina W; Shea, Steven; Muntner, Paul; Shimbo, Daichi

    2014-12-15

    The aim of this study was to test the hypothesis that depression and anxiety are associated with electrocardiographic (ECG) repolarization abnormalities in the Multi-Ethnic Study of Atherosclerosis (MESA), a cohort free of symptomatic cardiovascular disease. Depressive symptoms were assessed by using the Center for Epidemiologic Studies Depression Scale and trait anxiety symptoms by using the Spielberger State-Trait Anxiety Inventory; both were categorized according to uppermost quartile. T-wave inversions in ECG leads other than V1 to V3 were obtained from electrocardiograms obtained at rest during the baseline examination. Participants with major intraventricular conduction abnormalities and those taking antiarrhythmics, antidepressants, and/or antipsychotics were excluded. Logistic regression models were estimated with multivariable adjustment for traditional cardiovascular disease risk factors. Among 5,906 participants, elevated depressive symptoms were associated with increased odds of T-wave inversion after multivariable adjustment (odds ratio 2.02, 95% confidence interval 1.33 to 3.06, p = 0.001), whereas greater trait anxiety was associated with reduced odds of T-wave inversion (odds ratio 0.47, 95% confidence interval 0.29 to 0.77, p = 0.003). The divergent associations of depressive symptoms and trait anxiety with ECG T-wave inversions were similar in men and women, and these associations were present across the racial and ethnic subgroups (non-Hispanic white, African-American, Hispanic, and Chinese). In conclusion, symptoms of depression and anxiety were independently yet oppositely associated with ECG T-wave inversions. Negative emotions may have a differential impact on cardiovascular mortality through unique relations with cardiac repolarization. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Supersymmetric cascade decays at NLO

    Energy Technology Data Exchange (ETDEWEB)

    Popenda, Eva; Muehlleitner, Margarete; Hangst, Christian [KIT, Institut fuer Theoretische Physik (Germany); Kraemer, Michael [RWTH Aachen University, Institut fuer Theoretische Teilchenphysik und Kosmologie (Germany); Spira, Michael [Paul Scherrer Institut, Theory Group LTP (Switzerland)

    2012-07-01

    The search for supersymmetric particles and determination of their properties is a major task at the LHC and is based on the analysis of the cascade decay chains in which SUSY particles are produced. This project aims at improving predictions for SUSY cascade decays through the inclusion of higher-order corrections in the production and decay processes and by embedding them in a fully flexible Monte Carlo program. In this talk we report on the progress of the implementation of squark pair production followed by the decay into a quark and the lightest neutralino including supersymmetric QCD corrections at next-to-leading order in a completely differential form.

  13. Bosonic cascades of indirect excitons

    Science.gov (United States)

    Nalitov, A. V.; De Liberato, S.; Lagoudakis, P.; Savvidis, P. G.; Kavokin, A. V.

    2017-08-01

    Recently, the concept of the terahertz bosonic cascade laser (BCL) based on a parabolic quantum well (PQW) embedded in a microcavity was proposed. We refine this proposal by suggesting transitions between indirect exciton (IX) states as a source of terahertz emission. We explicitly propose a structure containing a narrow-square QW and a wide-parabolic QW for the realisation of a bosonic cascade. Advantages of this type of structures are in large dipole matrix elements for terahertz transitions and in long exciton radiative lifetimes which are crucial for realisation of threshold and quantum efficiency BCLs.

  14. Quantum cascade lasers for defense and security

    Science.gov (United States)

    Day, Timothy; Pushkarsky, Michael; Caffey, Dave; Cecchetti, Kristen; Arp, Ron; Whitmore, Alex; Henson, Michael; Takeuchi, Eric B.

    2013-10-01

    Quantum cascade laser (QCL) systems are mature and at the vanguard of a new generation of products that support military applications such as Infrared Countermeasures (IRCM) and targeting. The demanding product requirements for aircraft platforms that include reduced size, weight, power consumption and cost (SWaP-C) extends to portable, battery powered handheld products. QCL technology operates throughout the mid-wave (MWIR) and long-wave (LWIR) infrared to provide new capabilities that leverage existing thermal imaging cameras. In addition to their suitability for aircraft platforms, QCL products are a natural fit to meet operator demands for small, lightweight pointer and beacon capabilities. Field-testing of high power, lightweight, battery operated devices has demonstrated their utility across a range of air and ground applications. This talk will present an overview of QCL technology and the Defense and Security products and capabilities that are enabled by it. This talk will also provide an overview of the extensive environmental and performance testing associated with products based on QCL technology.

  15. Evaluation of Optic Nerve with Strain and Shear Wave Elastography in Patients with Behçet's Disease and Healthy Subjects.

    Science.gov (United States)

    Inal, Mikail; Tan, Sinan; Demirkan, Serkan; Burulday, Veysel; Gündüz, Özgür; Örnek, Kemal

    2017-07-01

    The objective of this study was to investigate the elasticity characteristics of the optic nerve using strain and shear wave elastography in patients with Behçet's disease and to compare the results with those of healthy volunteers. Forty-six optic nerves from patients with Behçet's disease and 54 optic nerves from healthy volunteers were investigated prospectively in this study using strain and shear wave elastography. There was a statistically significant difference in terms of elasticity patterns between patients and healthy volunteers (p < 0.001). Elastographic images of healthy volunteers revealed most optic nerves to be type 3 (51.8%); however, type 2 (40.7%) and type 1 (7.5%) were also observed. Elastographic examination of Behçet's disease patients revealed type 2 in 52.2%, type 1 in 43.5% and type 3 in 4.3% of patients. Statistically significant differences were observed between patients and healthy volunteers in the analysis of shear wave elastography values (p < 0.001). Receiver operating characteristic curve analysis was perfect (0.933) (95% CI = 0.885-0.980), and a cutoff value of 16.5 kPa shear had very high sensitivity and specificity for the patient group. Strain and shear wave elastography findings for the optic nerves of patients with Behçet's disease were significantly different from those for healthy volunteers. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  16. Effect of pulsed short-wave diathermy on pain and function of subjects with osteoarthritis of the knee: a placebo-controlled double-blind clinical trial.

    Science.gov (United States)

    Laufer, Y; Zilberman, R; Porat, R; Nahir, A M

    2005-05-01

    To examine the effects of pulsed short-wave diathermy (PSWD), delivered at an intensity sufficient to induce a thermal sensation and at an athermal intensity, in comparison with a placebo short-wave diathermy treatment, on reported pain, stiffness and functional ability and on mobility performance of patients with osteoarthritis of the knee. A placebo-controlled double-blind trial with sequential allocation of patients to different treatment groups. Outpatient physiotherapy department. One hundred and three consecutive patients, mean age 73.7 (+/-6.6) years with osteoarthritis of one or both knees for at least three months. All participants received three 20-min-long treatments per week for three weeks. One group received PSWD with mean power of 18 W (thermal effect), one group received PSWD with mean power of 1.8 W (athermal effect), and one group received sham short-wave diathermy treatment. Patients were assessed before the initial treatment, immediately following the last treatment, and at a three-month follow-up. Outcome measures included the WOMAC Osteoarthritis Index, which assessed reported pain, stiffness, and functional ability, and four measures of mobility performance: Timed Get Up and Go test (TGUG), stair-climbing, stair, descending and a 3-min walk. A difference across time was observed for the pain and stiffness categories of the WOMAC Osteoarthritis Index (p = 0.033 and p = 0.008, respectively), with no differences between groups. No other significant differences across time or between groups were observed in any of the other measures. The findings do not demonstrate pulsed short-wave diathermy, as it is utilized in clinical settings, to be effective in the treatment of osteoarthritis of the knee.

  17. Self-induced plantar-flexion objectively reduces wave amplitude of detrusor overactivity and subjectively improve urinary urgency: a pilot study.

    Science.gov (United States)

    Stav, Kobi; Leibovici, Dan; Yoram, Siegel I; Ronny, Ohlgisser; Zisman, Amnon

    2014-11-01

    To estimate the effect of plantar-flexion on the wave amplitude of involuntary detrusor contraction and the severity of urinary urgency during filling cystometry in patients with detrusor overactivity (DO). Twenty-two consecutive patients with DO were enrolled. During urodynamics, the mean peak detrusor pressures of each contraction were documented and compared. At the beginning of the 2nd or 3rd wave, patients were asked to perform continuous plantar-flexion by pushing their tiptoes against the floor. Following each wave, patients were asked to grade the severity of the urgency by a visual analogue scale (VAS). The mean peak detrusor pressure without plantar-flexion was 58 cmH2 O (95% CI: 46.3-69.7) compared to 31 cmH2 O (95% CI: 23.1-38.9) with plantar-flexion (P < 0.001). All patients reported a reduced degree of urgency during plantar-flexion reflected in a significant reduction in mean VAS score from 9.3 (95% CI: 9-9.5) to 4.7 (95% CI: 3.9-5.4; P < 0.0001). Self-performed plantar-flexion maneuver might reduce the severity of urinary urgency and the magnitude of overactive detrusor contractions, which may have a role in the conservative therapy of detrusor overactivity. © 2013 Wiley Periodicals, Inc.

  18. An Analytical Solution for Dynamic Response of Water Barrier Subjected to Strong Shock Waves Caused by an Underwater Explosion to Dams

    Directory of Open Access Journals (Sweden)

    Lu Lu

    2017-08-01

    Full Text Available Shock waves arriving at a dam site are close to plane waves when the center of an underwater explosion is far from the dam site. In general, the wave pressure is calculated with COLE empirical formula. The COLE formula is a negative exponential function with respect to time. In this paper, a new analytical solution algorithm is proposed, which does not require the use of step-by-step time integration. In Comparison with the step-by-step time integration, the proposed algorithm requires relatively less calculation and avoids high-frequency oscillation. Furthermore, the vertical upstream surface and the sloping upstream surface in two types of the dams are analyzed in this paper. The research results indicate that the analytical solution can be applied for a dam with a vertical upstream surface. However, because the upstream face of a dam is inclined, the analytical solution can be obtained only for dams that are at lower height. Whenever the height of a dam is higher, then no analytical solution can be obtained, and only the use of step-by-step time integration can obtain a solution.

  19. Cascaded logic gates in nanophotonic plasmon networks

    National Research Council Canada - National Science Library

    Wei, Hong; Wang, Zhuoxian; Tian, Xiaorui; Käll, Mikael; Xu, Hongxing

    2011-01-01

    ... integrated logic units and cascade devices have not been reported. Here we demonstrate that a plasmonic binary NOR gate, a 'universal logic gate', can be realized through cascaded OR and NOT gates in four-terminal plasmonic nanowire networks...

  20. Cascade Support Vector Machines with Dimensionality Reduction

    Directory of Open Access Journals (Sweden)

    Oliver Kramer

    2015-01-01

    Full Text Available Cascade support vector machines have been introduced as extension of classic support vector machines that allow a fast training on large data sets. In this work, we combine cascade support vector machines with dimensionality reduction based preprocessing. The cascade principle allows fast learning based on the division of the training set into subsets and the union of cascade learning results based on support vectors in each cascade level. The combination with dimensionality reduction as preprocessing results in a significant speedup, often without loss of classifier accuracies, while considering the high-dimensional pendants of the low-dimensional support vectors in each new cascade level. We analyze and compare various instantiations of dimensionality reduction preprocessing and cascade SVMs with principal component analysis, locally linear embedding, and isometric mapping. The experimental analysis on various artificial and real-world benchmark problems includes various cascade specific parameters like intermediate training set sizes and dimensionalities.

  1. Activation Cascading in Sign Production

    Science.gov (United States)

    Navarrete, Eduardo; Peressotti, Francesca; Lerose, Luigi; Miozzo, Michele

    2017-01-01

    In this study, we investigated how activation unfolds in sign production by examining whether signs that are not produced have their representations activated by semantics (cascading of activation). Deaf signers were tested with a picture-picture interference task. Participants were presented with pairs of overlapping pictures and named the green…

  2. Dynamics robustness of cascading systems.

    Directory of Open Access Journals (Sweden)

    Jonathan T Young

    2017-03-01

    Full Text Available A most important property of biochemical systems is robustness. Static robustness, e.g., homeostasis, is the insensitivity of a state against perturbations, whereas dynamics robustness, e.g., homeorhesis, is the insensitivity of a dynamic process. In contrast to the extensively studied static robustness, dynamics robustness, i.e., how a system creates an invariant temporal profile against perturbations, is little explored despite transient dynamics being crucial for cellular fates and are reported to be robust experimentally. For example, the duration of a stimulus elicits different phenotypic responses, and signaling networks process and encode temporal information. Hence, robustness in time courses will be necessary for functional biochemical networks. Based on dynamical systems theory, we uncovered a general mechanism to achieve dynamics robustness. Using a three-stage linear signaling cascade as an example, we found that the temporal profiles and response duration post-stimulus is robust to perturbations against certain parameters. Then analyzing the linearized model, we elucidated the criteria of when signaling cascades will display dynamics robustness. We found that changes in the upstream modules are masked in the cascade, and that the response duration is mainly controlled by the rate-limiting module and organization of the cascade's kinetics. Specifically, we found two necessary conditions for dynamics robustness in signaling cascades: 1 Constraint on the rate-limiting process: The phosphatase activity in the perturbed module is not the slowest. 2 Constraints on the initial conditions: The kinase activity needs to be fast enough such that each module is saturated even with fast phosphatase activity and upstream changes are attenuated. We discussed the relevance of such robustness to several biological examples and the validity of the above conditions therein. Given the applicability of dynamics robustness to a variety of systems, it

  3. Cascaded Bragg scattering in fiber optics.

    Science.gov (United States)

    Xu, Y Q; Erkintalo, M; Genty, G; Murdoch, S G

    2013-01-15

    We report on a theoretical and experimental study of cascaded Bragg scattering in fiber optics. We show that the usual energy-momentum conservation of Bragg scattering can be considerably relaxed via cascade-induced phase-matching. Experimentally we demonstrate frequency translation over six- and 11-fold cascades, in excellent agreement with derived phase-matching conditions.

  4. Phase-locking in cascaded stimulated Brillouin scattering

    CERN Document Server

    Büttner, Thomas F S; Steel, M J; Hudson, Darren D; Eggleton, Benjamin J

    2015-01-01

    Cascaded stimulated Brillouin scattering (SBS) is a complex nonlinear optical process that results in the generation of several optical waves that are frequency shifted by an acoustic resonance frequency. Four-wave mixing (FWM) between these Brillouin shifted optical waves can create an equally spaced optical frequency comb with a stable spectral phase, i.e. a Brillouin frequency comb (BFC). Here, we investigate phase-locking of the spectral components of BFCs, considering FWM interactions arising from the Kerr-nonlinearity as well as from coupling by the acoustic field. Deriving for the first time the coupled-mode equations that include all relevant nonlinear interactions, we examine the contribution of the various nonlinear processes to phase-locking, and show that different regimes can be obtained that depend on the length scale on which the field amplitudes vary.

  5. The E-wave propagation index (EPI): A novel echocardiographic parameter for prediction of left ventricular thrombus. Derivation from computational fluid dynamic modeling and validation on human subjects.

    Science.gov (United States)

    Harfi, Thura T; Seo, Jung-Hee; Yasir, Hayder S; Welsh, Nathaniel; Mayer, Susan A; Abraham, Theodore P; George, Richard T; Mittal, Rajat

    2017-01-15

    To describe the derivation and validation of a novel echocardiographic metric for prediction of left ventricle thrombus (LVT). Computational fluid dynamic modeling using cardiac CT images was used to derive a novel echocardiography-based metric to predict the presence of LVT. We retrospectively reviewed 25 transthoracic echocardiograms showing definite LVT (LVT group). We then randomly selected 25 patients with LVEF ≥55% (Normal EF group) and 25 patients with severe cardiomyopathy (CMP) with LVEF ≤40% without evidence of LVT (CMP group). The E-wave Propagation Index (EPI) was measured as the E-wave velocity time-integral divided by the LV length. An EPI>1 indicates penetration of the mitral jet into the apex whereas an EPIEPI was compared between the three groups. Crude and adjusted odd ratios of EPI and LVT association were also measured. Mean EPI was highest for the normal EF group and lowest in the LVT group (1.7 vs. 0.8; pEPI also differed significantly between LVT and CMP groups (0.8 vs. 1.2; pEPI EPI EPI of less than 1 is an independent predictor of LVT formation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. Nonlocal description of X waves in quadratic nonlinear materials

    DEFF Research Database (Denmark)

    Larsen, Peter Ulrik Vingaard; Sørensen, Mads Peter; Bang, Ole

    2006-01-01

    We study localized light bullets and X-waves in quadratic media and show how the notion of nonlocality can provide an alternative simple physical picture of both types of multi-dimensional nonlinear waves. For X-waves we show that a local cascading limit in terms of a nonlinear Schrodinger equation...

  7. Multi-component optical solitary waves

    DEFF Research Database (Denmark)

    Kivshar, Y. S.; Sukhorukov, A. A.; Ostrovskaya, E. A.

    2000-01-01

    We discuss several novel types of multi-component (temporal and spatial) envelope solitary waves that appear in fiber and waveguide nonlinear optics. In particular, we describe multi-channel solitary waves in bit-parallel-wavelength fiber transmission systems for highperformance computer networks......, multi-color parametric spatial solitary waves due to cascaded nonlinearities of quadratic materials, and quasiperiodic envelope solitons due to quasi-phase-matching in Fibonacci optical superlattices. (C) 2000 Elsevier Science B.V. All rights reserved....

  8. Effect of a gas on the ejection of particles from the free surface of a sample subjected to a shock wave with various intensities

    Energy Technology Data Exchange (ETDEWEB)

    Ogorodnikov, V. A., E-mail: root@gdd.vniief.ru; Mikhailov, A. L.; Sasik, V. S.; Erunov, S. V.; Syrunin, M. A.; Fedorov, A. V.; Nevmerzhitskii, N. V.; Kulakov, E. V.; Kleshchevnikov, O. A.; Antipov, M. V.; Yurtov, I. V.; Rudnev, A. V.; Chapaev, A. V.; Pupkov, A. S.; Sen’kovskii, E. D.; Sotskov, E. A.; Glushikhin, V. V.; Kalashnik, I. A.; Finyushin, S. A.; Chudakov, E. A. [Russian Federal Nuclear Center All-Russia Research Institute of Experimental Physics (VNIIEF) (Russian Federation); and others

    2016-08-15

    In view of the possible effect of contamination of a plasma by metal particles on the operation of a number of facilities or on the detection of the motion of liners by Doppler methods, a particular attention has been recently focused on the problem of the ejection of particles from the shock-loaded free surface of a sample or on the “dusting” problem. Most information concerns the dusting source associated with the roughness of the surface, manufacturing technology, and the defectiveness and aging of a material. Factors affecting this process such as the profile and amplitude of the pressure on the front of the shock wave arriving at the free surface of the sample, the presence of the gas in front of the free surface, and the pressure in this gas are less studied.

  9. Neuro-fuzzy control strategy for an offshore steel jacket platform subjected to wave-induced forces using magneto rheological dampers

    Energy Technology Data Exchange (ETDEWEB)

    Sarrafan, Atabak; Zareh, Seiyed Hamid; Khayyat, Amir Ali Akbar; Zabihollah, Abolghassem [Sharif University of Technology, Teheran (Iran, Islamic Republic of)

    2012-04-15

    Magnetorheological (MR) damper is a prominent semi-active control device to vibrate mitigation of structures. Due to the inherent non-linear nature of MR damper, an intelligent non-linear neuro-fuzzy control strategy is designed to control wave-induced vibration of an offshore steel jacket platform equipped with MR dampers. In the proposed control system, a dynamic-feedback neural network is adapted to model non-linear dynamic system, and the fuzzy logic controller is used to determine the control forces of MR dampers. By use of two feed forward neural networks required voltages and actual MR damper forces are obtained, in which the first neural network and the second one acts as the inverse dynamics model, and the forward dynamics model of the MR dampers, respectively. The most important characteristic of the proposed intelligent control strategy is its inherent robustness and its ability to handle the non-linear behavior of the system. Besides, no mathematical model needed to calculate forces produced by MR dampers. According to linearized Morison equation, wave-induced forces are determined. The performance of the proposed neuro-fuzzy control system is compared with that of a traditional semi-active control strategy, i.e., clipped optimal control system with LQG-target controller, through computer simulations, while the uncontrolled system response is used as the baseline. It is demonstrated that the design of proposed control system framework is more effective than that of the clipped optimal control scheme with LQG-target controller to reduce the vibration of offshore structure. Furthermore, the control strategy is very important for semi-active control.

  10. Transfer functions of laminar premixed flames subjected to forcing by acoustic waves, AC electric fields, and non-thermal plasma discharges

    KAUST Repository

    Lacoste, Deanna

    2016-06-23

    The responses of laminar methane-air flames to forcing by acoustic waves, AC electric fields, and nanosecond repetitively pulsed (NRP) glow discharges are reported here. The experimental setup consists of an axisymmetric burner with a nozzle made from a quartz tube. Three different flame geometries have been studied: conical, M-shaped and V-shaped flames. A central stainless steel rod is used as a cathode for the electric field and plasma excitations. The acoustic forcing is obtained with a loudspeaker located at the bottom part of the burner. For forcing by AC electric fields, a metallic grid is placed above the rod and connected to an AC power supply. Plasma forcing is obtained by applying high-voltage pulses of 10-ns duration applied at 10 kHz, between the rod and an annular stainless steel ring, placed at the outlet of the quartz tube. The chemiluminescence of CH is used to determine the heat release rate fluctuations. For forcing by acoustic waves and plasma, the geometry of the flame plays a key role in the response of the combustion, while the flame shape does not affect the response of the combustion to electric field forcing. The flame response to acoustic forcing of about 10% of the incoming flow is similar to those obtained in the literature. The flames are found to be responsive to an AC electric field across the whole range of frequencies studied. A forcing mechanism, based on the generation of ionic wind, is proposed. The gain of the transfer function obtained for plasma forcing is found to be up to 5 times higher than for acoustic forcing. A possible mechanism of plasma forcing is introduced.

  11. Bankruptcy cascades in interbank markets.

    Directory of Open Access Journals (Sweden)

    Gabriele Tedeschi

    Full Text Available We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank's liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable.

  12. Thermal cascaded lattice Boltzmann method

    CERN Document Server

    Fei, Linlin

    2016-01-01

    In this paper, a thermal cascaded lattice Boltzmann method (TCLBM) is developed in combination with the double-distribution-function (DDF) approach. A density distribution function relaxed by the cascaded scheme is employed to solve the flow field, and a total energy distribution function relaxed by the BGK scheme is used to solve temperature field, where two distribution functions are coupled naturally. The forcing terms are incorporated by means of central moments, which is consistent with the previous force scheme [Premnath \\emph{et al.}, Phys. Rev. E \\textbf{80}, 036702 (2009)] but the derivation is more intelligible and the evolution process is simpler. In the method, the viscous heat dissipation and compression work are taken into account, the Prandtl number and specific-heat ratio are adjustable, the external force is considered directly without the Boussinesq assumption, and the low-Mach number compressible flows can also be simulated. The forcing scheme is tested by simulating a steady Taylor-Green f...

  13. Lens Coupled Quantum Cascade Laser

    Science.gov (United States)

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)

    2013-01-01

    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  14. Psychosocial job quality, mental health, and subjective wellbeing: a cross-sectional analysis of the baseline wave of the Australian Longitudinal Study on Male Health.

    Science.gov (United States)

    LaMontagne, Anthony D; Milner, Allison; Krnjacki, Lauren; Schlichthorst, Marisa; Kavanagh, Anne; Page, Kathryn; Pirkis, Jane

    2016-10-31

    Employment status and working conditions are strong determinants of male health, and are therefore an important focus in the Australian Longitudinal Study on Male Health (Ten to Men). In this paper, we describe key work variables included in Ten to Men, and present analyses relating psychosocial job quality to mental health and subjective wellbeing at baseline. A national sample of males aged 10 to 55 years residing in private dwellings was drawn using a stratified multi-stage cluster random sample design. Data were collected between October 2013 and July 2014 for a cohort of 15,988 males, representing a response fraction of 35 %. This analysis was restricted to 18-55 year old working age participants (n = 13,456). Work-related measures included employment status, and, for those who were employed, a number of working conditions including an ordinal scale of psychosocial job quality (presence of low job control, high demand and complexity, high job insecurity, and low fairness of pay), and working time-related stressors such as long working hours and night shift work. Associations between psychosocial job quality and two outcome measures, mental ill-health and subjective wellbeing, were assessed using multiple linear regression. The majority of participants aged 18-55 years were employed at baseline (85.6 %), with 8.4 % unemployed and looking for work, and 6.1 % not in the labour force. Among employed participants, there was a high prevalence of long working hours (49.9 % reported working more than 40 h/week) and night shift work (23.4 %). Psychosocial job quality (exposure to 0/1/2/3+ job stressors) prevalence was 36 %/ 37 %/ 20 %/ and 7 % of the working respondents. There was a dose-response relationship between psychosocial job quality and each of the two outcome measures of mental health and subjective wellbeing after adjusting for potential confounders, with higher magnitude associations between psychosocial job quality and subjective wellbeing

  15. Advanced Dementia Research in the Nursing Home: The CASCADE Study

    Science.gov (United States)

    Mitchell, Susan L.; Kiely, Dan K.; Jones, Richard N.; Prigerson, Holly; Volicer, Ladislav; Teno, Joan M.

    2009-01-01

    Despite the growing number of persons with advanced dementia, and the need to improve their end-of-life care, few studies have addressed this important topic. The objectives of this report are to present the methodology established in the CASCADE (Choices, Attitudes, and Strategies for Care of Advanced Dementia at the End-of-Life) study, and to describe how challenges specific to this research were met. The CASCADE study is an ongoing, federally funded, 5-year prospective cohort study of nursing [nursing home (NH)] residents with advanced dementia and their health care proxies (HCPs) initiated in February 2003. Subjects were recruited from 15 facilities around Boston. The recruitment and data collection protocols are described. The demographic features, ownership, staffing, and quality of care of participant facilities are presented and compared to NHs nationwide. To date, 189 resident/HCP dyads have been enrolled. Baseline data are presented, demonstrating the success of the protocol in recruiting and repeatedly assessing NH residents with advanced dementia and their HCPs. Factors challenging and enabling implementation of the protocol are described. The CASCADE experience establishes the feasibility of conducting rigorous, multisite dementia NH research, and the described methodology serves as a detailed reference for subsequent CASCADE publications as results from the study emerge. PMID:16917187

  16. Skeletal Muscle in Healthy Subjects versus Those with GNE-Related Myopathy: Evaluation with Shear-Wave US--A Pilot Study.

    Science.gov (United States)

    Carpenter, Elizabeth L; Lau, Heather A; Kolodny, Edwin H; Adler, Ronald S

    2015-11-01

    To determine whether quantitative differences in shear-wave velocity (SWV) exist between normal skeletal muscle and those affected by GNE-related myopathy and to examine the effects of muscle anisotropy, depth, and axial preload on SWV in a healthy control group. This study was approved by the institutional review board and compliant with HIPAA. Informed consent was obtained from all study volunteers. Eight patients (four women and four men aged 30-50 years) with genetically and biopsy-proved GNE-related myopathy and five healthy volunteers (three women and two men aged 27-33 years) underwent SWV imaging with use of a 9-MHz linear transducer. The gastrocnemius muscles were evaluated in the patients with GNE-related myopathy, and the gastrocnemius, vastus lateralis, and rectus femoris muscles were evaluated in the healthy cohort. The effect of muscle anisotropy, axial preload, and sample volume depth were examined in the healthy cohort. The effect of anisotropy at a fixed depth and preload were examined in the patients with GNE-related myopathy. Irrespective of the muscle, the mean SWV was significantly higher with the transverse orientation than with the longitudinal orientation (P muscle anisotropy in GNE-related myopathy. © RSNA, 2015

  17. MCDF calculations of Auger cascade processes

    Science.gov (United States)

    Beerwerth, Randolf; Fritzsche, Stephan

    2017-10-01

    We model the multiple ionization of near-neutral core-excited atoms where a cascade of Auger processes leads to the emission of several electrons. We utilize the multiconfiguration Dirac-Fock (MCDF) method to generate approximate wave functions for all fine-structure levels and to account for all decays between them. This approach allows to compute electron spectra, the population of final-states and ion yields, that are accessible in many experiments. Furthermore, our approach is based on the configuration interaction method. A careful treatment of correlation between electronic configurations enables one to model three-electron processes such as an Auger decay that is accompanied by an additional shake-up transition. Here, this model is applied to the triple ionization of atomic cadmium, where we show that the decay of inner-shell 4p holes to triply-charged final states is purely due to the shake-up transition of valence 5s electrons. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, Grzegorz Karwasz.

  18. [Possible effects of climate changes (particularly heat waves) on body functions with a special emphasis on subjects taking psychopharmacons: a narrative review].

    Science.gov (United States)

    Radics, Judit

    2016-03-01

    Climate change and global warming have become increasingly discussed in the last few years - but mainly as an economical-social problem. Due to the preceding years' hot summers, as a clinical psychiatrist I considered it important to examine the effect of heat on body functions especially among those who are taking psychiatric drugs. The problem has a clinical significance, since heat is an extreme environmental factor with unexpected consequences. Due to heat various adverse reactions are expected especially in subjects on combined pharmacotherapy regimes. The present article points out the clinical importance of heat and also its potential adverse (and sometimes life-threatening) consequences.

  19. DECREASING OF WATER TROPHY IN CASCADE SYSTEMS, ON EXAMPLE OF THE SOŁA RIVER DAM CASCADE (SOUTHERN POLAND

    Directory of Open Access Journals (Sweden)

    Ewa Jachniak

    2014-10-01

    Full Text Available In this thesis the subject of water self-purification in cascade systems of water reservoirs was engaged. The results of hydrobiological research of three dam reservoirs (Tresna, Porąbka and Czaniec, creating the Soła river dam cascade were presented. The trophic status of these reservoirs was defined on the grounds of the concentration of chlorophyll a, biomass of phytoplankton and occurrence of indicating species of planktonic algae. The results of research indicated on decreasing of water trophy in the layout from the highest into the lowest reservoir of the cascade. The average concentrations of chlorophyll a amounted appropriately 19,99 μg·dm-3, 8,74 μg·dm-3 and 4,29 μg·dm-3, instead the average biomass of phytoplankton amounted appropriately 4,1 mg·dm-3, 3,4 mg·dm-3 and 0,1 mg·dm-3. The observed species of algae confirmed occurrence of differences between reservoirs. In Tresna reservoir more species of phytoplankton indicating for eutrophy were thrived, instead in Porąbka and Czaniec reservoirs the species occurring in oligomesotrophic water thrived. Water self-purification in the Soła river dam cascade expressed decreasing of their fertility is important for water management of the region, because the Czaniec reservoir fulfill a function of water-supply reservoir.

  20. Intermittent Flow Regimes in a Transonic Fan Airfoil Cascade

    Science.gov (United States)

    Lepicovsky, J.; McFarland, E. R.; Chima, R. V.; Capece, V. R.; Hayden, J.

    2002-01-01

    A study was conducted in the NASA Glenn Research Center linear cascade on the intermittent flow on the suction surface of an airfoil section from the tip region of a modern low aspect ratio fan blade. Experimental results revealed that, at a large incidence angle, a range of transonic inlet Mach numbers exist where the leading-edge shock-wave pattern was unstable. Flush mounted high frequency response pressure transducers indicated large local jumps in the pressure in the leading edge area, which generates large intermittent loading on the blade leading edge. These measurements suggest that for an inlet Mach number between 0.9 and 1.0 the flow is bi-stable, randomly switching between subsonic and supersonic flows. Hence, it appears that the change in overall flow conditions in the transonic region is based on the frequency of switching between two stable flow states rather than on the continuous increase of the flow velocity. To date, this flow behavior has only been observed in a linear transonic cascade. Further research is necessary to confirm this phenomenon occurs in actual transonic fans and is not the byproduct of an endwall restricted linear cascade.

  1. Azobenzene-functionalized cascade molecules

    DEFF Research Database (Denmark)

    Archut, A.; Vogtle, F.; De Cola, L.

    1998-01-01

    Cascade molecules bearing up to 32 azobenzene groups in the periphery have been prepared from poly(propylene imine) dendrimers and N-hydroxysuccinimide esters. The dendritic azobenzene species show similar isomerization properties as the corresponding azobenzene monomers. The all-E azobenzene...... shows there is so far no effective steric constraint towards photoisomerism on increasing dimension (generation) of the dendrimer, The first attempts to use dendrimers for holography materials are described: It is shown that holographic gratings with diffraction efficiencies up to about 20 % can...

  2. Disaster Mythology and Availability Cascades

    Directory of Open Access Journals (Sweden)

    Lisa Grow Sun

    2013-04-01

    Full Text Available Sociological research conducted in the aftermath of natural disasters has uncovered a number of “disaster myths” – widely shared misconceptions about typical post-disaster human behavior. This paper discusses the possibility that perpetuation of disaster mythology reflects an “availability cascade,” defined in prior scholarship as a “self-reinforcing process of collective belief formation by which an expressed perception triggers a chain reaction that gives the perception increasing plausibility through its rising availability in public discourse.” (Kuran and Sunstein 1999. Framing the spread of disaster mythology as an availability cascade suggests that certain tools may be useful in halting the myths’ continued perpetuation. These tools include changing the legal and social incentives of so-called “availability entrepreneurs” – those principally responsible for beginning and perpetuating the cascade, as well as insulating decision-makers from political pressures generated by the availability cascade. This paper evaluates the potential effectiveness of these and other solutions for countering disaster mythology. Las investigaciones sociológicas realizadas tras los desastres naturales han hecho evidentes una serie de “mitos del desastre”, conceptos erróneos ampliamente compartidos sobre el comportamiento humano típico tras un desastre. Este artículo analiza la posibilidad de que la perpetuación de los mitos del desastre refleje una “cascada de disponibilidad”, definida en estudios anteriores como un “proceso de auto-refuerzo de la formación de una creencia colectiva, a través del que una percepción expresada produce una reacción en cadena que hace que la percepción sea cada vez más verosímil, a través de una mayor presencia en el discurso público” (Kuran y Sunstein 1999. Enmarcar la propagación de los mitos del desastre como una cascada de disponibilidad sugiere que ciertas herramientas pueden ser

  3. WHISTLER TURBULENCE FORWARD CASCADE VERSUS INVERSE CASCADE: THREE-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Ouliang [Oracle Corporation, Redwood Shores, CA (United States); Gary, S. Peter [Space Science Institute, Boulder, CO (United States); Wang, Joseph, E-mail: ouliang@usc.edu, E-mail: pgary@lanl.gov, E-mail: josephjw@usc.edu [University of Southern California, Los Angeles, CA (United States)

    2015-02-20

    We present the results of the first fully three-dimensional particle-in-cell simulations of decaying whistler turbulence in a magnetized, homogeneous, collisionless plasma in which both forward cascades to shorter wavelengths, and inverse cascades to longer wavelengths are allowed to proceed. For the electron beta β {sub e} = 0.10 initial value considered here, the early-time rate of inverse cascade is very much smaller than the rate of forward cascade, so that at late times the fluctuation energy in the regime of the inverse cascade is much weaker than that in the forward cascade regime. Similarly, the wavevector anisotropy in the inverse cascade regime is much weaker than that in the forward cascade regime.

  4. Cascading rainfall uncertainty into flood inundation impact models

    Science.gov (United States)

    Souvignet, Maxime; Freer, Jim E.; de Almeida, Gustavo A. M.; Coxon, Gemma; Neal, Jeffrey C.; Champion, Adrian J.; Cloke, Hannah L.; Bates, Paul D.

    2014-05-01

    Observed and numerical weather prediction (NWP) simulated precipitation products typically show differences in their spatial and temporal distribution. These differences can considerably influence the ability to predict hydrological responses. For flood inundation impact studies, as in forecast situations, an atmospheric-hydrologic-hydraulic model chain is needed to quantify the extent of flood risk. Uncertainties cascaded through the model chain are seldom explored, and more importantly, how potential input uncertainties propagate through this cascade, and how best to approach this, is still poorly understood. This requires a combination of modelling capabilities, the non-linear transformation of rainfall to river flow using rainfall-runoff models, and finally the hydraulic flood wave propagation based on the runoff predictions. Improving the characterisation of uncertainty, and what is important to include, in each component is important for quantifying impacts and understanding flood risk for different return periods. In this paper, we propose to address this issue by i) exploring the effects of errors in rainfall on inundation predictive capacity within an uncertainty framework by testing inundation uncertainty against different comparable meteorological conditions (i.e. using different rainfall products) and ii) testing different techniques to cascade uncertainties (e.g. bootstrapping, PPU envelope) within the GLUE (generalised likelihood uncertainty estimation) framework. Our method cascades rainfall uncertainties into multiple rainfall-runoff model structures using the Framework for Understanding Structural Errors (FUSE). The resultant prediction uncertainties in upstream discharge provide uncertain boundary conditions that are cascaded into a simplified shallow water hydraulic model (LISFLOOD-FP). Rainfall data captured by three different measurement techniques - rain gauges, gridded radar data and numerical weather predictions (NWP) models are evaluated

  5. Contingency Analysis of Cascading Line Outage Events

    Energy Technology Data Exchange (ETDEWEB)

    Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

    2011-03-01

    As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

  6. Optical Cherenkov radiation by cascaded nonlinear interaction: an efficient source of few-cycle energetic near- to mid-IR pulses

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Zhou, Binbin

    2011-01-01

    When ultrafast noncritical cascaded second-harmonic generation of energetic femtosecond pulses occur in a bulk lithium niobate crystal optical Cherenkov waves are formed in the near- to mid-IR. Numerical simulations show that the few-cycle solitons radiate Cherenkov (dispersive) waves in the λ = ...... efficiency is up to 25%. Thus, optical Cherenkov waves formed with cascaded nonlinearities could become an efficient source of energetic near- to mid-IR few-cycle pulses.......When ultrafast noncritical cascaded second-harmonic generation of energetic femtosecond pulses occur in a bulk lithium niobate crystal optical Cherenkov waves are formed in the near- to mid-IR. Numerical simulations show that the few-cycle solitons radiate Cherenkov (dispersive) waves in the λ = 2...

  7. Physics of interband cascade lasers

    Science.gov (United States)

    Vurgaftman, I.; Bewley, W. W.; Merritt, C. D.; Canedy, C. L.; Kim, C. S.; Abell, J.; Meyer, J. R.; Kim, M.

    2012-01-01

    The interband cascade laser (ICL) is a unique device concept that combines the effective parallel connection of its multiple-quantum-well active regions, interband active transitions, and internal generation of electrons and holes at a semimetallic interface within each stage of the device. The internal generation of carriers becomes effective under bias, and the role of electrical injection is to replenish the carriers consumed by recombination processes. Major strides have been made toward fundamentally understanding the rich and intricate ICL physics, which has in turn led to dramatic improvements in the device performance. In this article, we review the physical principles of the ICL operation and designs of the active region, electron and hole injectors, and optical waveguide. The results for state-of- the-art ICLs spanning the 3-6 μm wavelength range are also briefly reviewed. The cw threshold input powers at room temperature are more than an order of magnitude lower than those for quantum cascade lasers throughout the mid-IR spectral range. This will lengthen battery lifetimes and greatly relax packaging and size/weight requirements for fielded sensing systems.

  8. Lifespans of Cascade Arc volcanoes

    Science.gov (United States)

    Calvert, A. T.

    2015-12-01

    Compiled argon ages reveal inception, eruptive episodes, ages, and durations of Cascade stratovolcanoes and their ancestral predecessors. Geologic mapping and geochronology show that most Cascade volcanoes grew episodically on multiple scales with periods of elevated behavior lasting hundreds of years to ca. 100 kyr. Notable examples include the paleomag-constrained, few-hundred-year-long building of the entire 15-20 km3 Shastina edifice at Mt. Shasta, the 100 kyr-long episode that produced half of Mt. Rainier's output, and the 30 kyr-long episode responsible for all of South and Middle Sister. Despite significant differences in timing and rates of construction, total durations of active and ancestral volcanoes at discrete central-vent locations are similar. Glacier Peak, Mt. Rainier, Mt. Adams, Mt. Hood, and Mt. Mazama all have inception ages of 400-600 ka. Mt. St. Helens, Mt. Jefferson, Newberry Volcano, Mt. Shasta and Lassen Domefield have more recent inception ages of 200-300 ka. Only the Sisters cluster and Mt. Baker have established eruptive histories spanning less than 50 kyr. Ancestral volcanoes centered 5-20 km from active stratocones appear to have similar total durations (200-600 kyr), but are less well exposed and dated. The underlying mechanisms governing volcano lifecycles are cryptic, presumably involving tectonic and plumbing changes and perhaps circulation cycles in the mantle wedge, but are remarkably consistent along the arc.

  9. A Semisupervised Cascade Classification Algorithm

    Directory of Open Access Journals (Sweden)

    Stamatis Karlos

    2016-01-01

    Full Text Available Classification is one of the most important tasks of data mining techniques, which have been adopted by several modern applications. The shortage of enough labeled data in the majority of these applications has shifted the interest towards using semisupervised methods. Under such schemes, the use of collected unlabeled data combined with a clearly smaller set of labeled examples leads to similar or even better classification accuracy against supervised algorithms, which use labeled examples exclusively during the training phase. A novel approach for increasing semisupervised classification using Cascade Classifier technique is presented in this paper. The main characteristic of Cascade Classifier strategy is the use of a base classifier for increasing the feature space by adding either the predicted class or the probability class distribution of the initial data. The classifier of the second level is supplied with the new dataset and extracts the decision for each instance. In this work, a self-trained NB∇C4.5 classifier algorithm is presented, which combines the characteristics of Naive Bayes as a base classifier and the speed of C4.5 for final classification. We performed an in-depth comparison with other well-known semisupervised classification methods on standard benchmark datasets and we finally reached to the point that the presented technique has better accuracy in most cases.

  10. Bidirectional Energy Cascades and the Origin of Kinetic Alfvenic and Whistler Turbulence in the Solar Wind

    Science.gov (United States)

    Che, H.; Goldstein, M. L.; Vinas, A. F.

    2014-01-01

    The observed steep kinetic scale turbulence spectrum in the solar wind raises the question of how that turbulence originates. Observations of keV energetic electrons during solar quiet time suggest them as a possible source of free energy to drive kinetic turbulence. Using particle-in-cell simulations, we explore how the free energy released by an electron two-stream instability drives Weibel-like electromagnetic waves that excite wave-wave interactions. Consequently, both kinetic Alfvénic and whistler turbulence are excited that evolve through inverse and forward magnetic energy cascades.

  11. Power quality enhancement using cascaded multilevel inverter ...

    African Journals Online (AJOL)

    This paper investigates mitigation of current harmonics using different configuration of cascaded multilevel inverter based shunt hybrid active power filter (SHAPF) and to improve power quality of the system. The main objective of this paper is to develop and analyze the compensation characteristics of cascaded multilevel ...

  12. Cascading disaster models in postburn flash flood

    Science.gov (United States)

    Fred May

    2007-01-01

    A useful method of modeling threats from hazards and documenting their disaster causation sequences is called “cascading threat modeling.” This type of modeling enables emergency planners to address hazard and risk assessments systematically. This paper describes a cascading threat modeling and analysis process. Wildfire and an associated postburn flash flood disaster...

  13. Cascade Harvest’ red raspberry

    Science.gov (United States)

    Cascade Harvest’ is a new floricane fruiting raspberry cultivar (Rubus idaeus L.) jointly released by Washington State University (WSU), Oregon State University (OSU) and the U.S. Department of Agriculture (USDA). ‘Cascade Harvest’ produces a high yield of large, firm fruit suited to machine harves...

  14. Effects of acoustic waves on stick-slip in granular media and implications for earthquakes

    Science.gov (United States)

    Johnson, P.A.; Savage, H.; Knuth, M.; Gomberg, J.; Marone, Chris

    2008-01-01

    It remains unknown how the small strains induced by seismic waves can trigger earthquakes at large distances, in some cases thousands of kilometres from the triggering earthquake, with failure often occurring long after the waves have passed. Earthquake nucleation is usually observed to take place at depths of 10-20 km, and so static overburden should be large enough to inhibit triggering by seismic-wave stress perturbations. To understand the physics of dynamic triggering better, as well as the influence of dynamic stressing on earthquake recurrence, we have conducted laboratory studies of stick-slip in granular media with and without applied acoustic vibration. Glass beads were used to simulate granular fault zone material, sheared under constant normal stress, and subject to transient or continuous perturbation by acoustic waves. Here we show that small-magnitude failure events, corresponding to triggered aftershocks, occur when applied sound-wave amplitudes exceed several microstrain. These events are frequently delayed or occur as part of a cascade of small events. Vibrations also cause large slip events to be disrupted in time relative to those without wave perturbation. The effects are observed for many large-event cycles after vibrations cease, indicating a strain memory in the granular material. Dynamic stressing of tectonic faults may play a similar role in determining the complexity of earthquake recurrence. ??2007 Nature Publishing Group.

  15. Effects of acoustic waves on stick-slip in granular media and implications for earthquakes.

    Science.gov (United States)

    Johnson, Paul A; Savage, Heather; Knuth, Matt; Gomberg, Joan; Marone, Chris

    2008-01-03

    It remains unknown how the small strains induced by seismic waves can trigger earthquakes at large distances, in some cases thousands of kilometres from the triggering earthquake, with failure often occurring long after the waves have passed. Earthquake nucleation is usually observed to take place at depths of 10-20 km, and so static overburden should be large enough to inhibit triggering by seismic-wave stress perturbations. To understand the physics of dynamic triggering better, as well as the influence of dynamic stressing on earthquake recurrence, we have conducted laboratory studies of stick-slip in granular media with and without applied acoustic vibration. Glass beads were used to simulate granular fault zone material, sheared under constant normal stress, and subject to transient or continuous perturbation by acoustic waves. Here we show that small-magnitude failure events, corresponding to triggered aftershocks, occur when applied sound-wave amplitudes exceed several microstrain. These events are frequently delayed or occur as part of a cascade of small events. Vibrations also cause large slip events to be disrupted in time relative to those without wave perturbation. The effects are observed for many large-event cycles after vibrations cease, indicating a strain memory in the granular material. Dynamic stressing of tectonic faults may play a similar role in determining the complexity of earthquake recurrence.

  16. Suppressing cascades of load in interdependent networks

    CERN Document Server

    Brummitt, Charles D; Leicht, E A

    2011-01-01

    Understanding how interdependence among systems affects cascading behaviors is increasingly important across many fields of science and engineering. Inspired by cascades of load shedding in coupled electric grids and other infrastructure, we study the Bak-Tang-Wiesenfeld sandpile model on modular random graphs and on graphs based on actual, interdependent power grids. Starting from two isolated networks, adding some connectivity between them is beneficial, for it suppresses the largest cascades in each system. Too much interconnectivity, however, becomes detrimental for two reasons. First, interconnections open pathways for neighboring networks to inflict large cascades. Second, as in real infrastructure, new interconnections increase capacity and total possible load, which fuels even larger cascades. Using a multi-type branching process and simulations we show these effects and estimate the optimal level of interconnectivity that balances their tradeoffs. Such equilibria could allow, for example, power grid ...

  17. MAPK cascades in guard cell signal transduction

    Directory of Open Access Journals (Sweden)

    Yuree eLee

    2016-02-01

    Full Text Available Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions.

  18. Experimental study of flow through compressor Cascade

    Directory of Open Access Journals (Sweden)

    Satyam Panchal

    2017-09-01

    Full Text Available The objective of this research work is to study the behaviour of flow at the inlet, within the blade passage and at the exit of a compressor cascade. For this purpose, a cascade with six numbers of aerofoil blades was designed and constructed. The cascade was fitted on the cascade test tunnel. Out of six blades two were instrumented for measuring the pressure distribution on the pressure and suction surface. The blades had a parabolic camber line, with a maximum camber position at 40% of the chord from the leading edge of the blade. The profile of the blade was C4, height of the blade was 160 mm, chord length was 80 mm, camber angle was 45° and stagger angle was 30°. Similarly, the length of the cascade was 300 mm, span was 160 mm, pitch was 60 mm, the actual chord of the cascade was 80 mm, the axial chord of the cascade was 70 mm, the stagger angle of the cascade was 30° and the pitch-chord ratio was 0.75. The data was taken and analyzed at −500% of the axial chord before the cascade, −25% of the axial chord before the leading edge, 25%, 50%, 75% and 150% of the axial chord from the leading edge of the blade. The readings were taken from the cascade wall to the mid span position along the pitch wise direction. The angle of incidence was also changed during the experiment and varied from i=−50°, −30°, −10° to 5°.

  19. The blue light indicator in rubidium 5S-5P-5D cascade excitation

    Science.gov (United States)

    Raja, Waseem; Ali, Md. Sabir; Chakrabarti, Alok; Ray, Ayan

    2017-07-01

    The cascade system has played an important role in contemporary research areas related to fields like Rydberg excitation, four wave mixing and non-classical light generation, etc. Depending on the specific objective, co or counter propagating pump-probe laser experimental geometry is followed. However, the stepwise excitation of atoms to states higher than the first excited state deals with increasingly much fewer number of atoms even compared to the population at first excited level. Hence, one needs a practical indicator to study the complex photon-atom interaction of the cascade system. Here, we experimentally analyze the case of rubidium 5S → 5P → 5D as a specimen of two-step excitation and highlight the efficacy of monitoring one branch, which emits 420 nm, of associated cascade decay route 5D → 6P → 5S, as an effective monitor of the coherence in the system.

  20. W-Band Millimeter-Wave Vector Signal Generation Based on Precoding-Assisted Random Photonic Frequency Tripling Scheme Enabled by Phase Modulator

    National Research Council Canada - National Science Library

    Li, Xinying; Xu, Yuming; Xiao, Jiangnan; Yu, Jianjun

    2016-01-01

    We propose W-band photonic millimeter-wave (mm-wave) vector signal generation employing a precoding-assisted random frequency tripling scheme enabled by a single phase modulator cascaded with a wavelength selective switch (WSS...

  1. MAPK cascade signalling networks in plant defence.

    Science.gov (United States)

    Pitzschke, Andrea; Schikora, Adam; Hirt, Heribert

    2009-08-01

    The sensing of stress signals and their transduction into appropriate responses is crucial for the adaptation and survival of plants. Kinase cascades of the mitogen-activated protein kinase (MAPK) class play a remarkably important role in plant signalling of a variety of abiotic and biotic stresses. MAPK cascade-mediated signalling is an essential step in the establishment of resistance to pathogens. Here, we describe the most recent insights into MAPK-mediated pathogen defence response regulation with a particular focus on the cascades involving MPK3, MPK4 and MPK6. We also discuss the strategies developed by plant pathogens to circumvent, inactivate or even 'hijack' MAPK-mediated defence responses.

  2. Limits of Predictability of Cascading Overload Failures in Spatially-Embedded Networks with Distributed Flows.

    Science.gov (United States)

    Moussawi, A; Derzsy, N; Lin, X; Szymanski, B K; Korniss, G

    2017-09-15

    Cascading failures are a critical vulnerability of complex information or infrastructure networks. Here we investigate the properties of load-based cascading failures in real and synthetic spatially-embedded network structures, and propose mitigation strategies to reduce the severity of damages caused by such failures. We introduce a stochastic method for optimal heterogeneous distribution of resources (node capacities) subject to a fixed total cost. Additionally, we design and compare the performance of networks with N-stable and (N-1)-stable network-capacity allocations by triggering cascades using various real-world node-attack and node-failure scenarios. We show that failure mitigation through increased node protection can be effectively achieved against single-node failures. However, mitigating against multiple node failures is much more difficult due to the combinatorial increase in possible sets of initially failing nodes. We analyze the robustness of the system with increasing protection, and find that a critical tolerance exists at which the system undergoes a phase transition, and above which the network almost completely survives an attack. Moreover, we show that cascade-size distributions measured in this region exhibit a power-law decay. Finally, we find a strong correlation between cascade sizes induced by individual nodes and sets of nodes. We also show that network topology alone is a weak predictor in determining the progression of cascading failures.

  3. Astrophysical Gyrokinetics: Kinetic and Fluid Turbulent Cascades In Magentized Weakly Collisional Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Schekochihin, A. A.; Cowley, S. C.; Dorland, W.; Hammett, G. W.; Howes, G. G.; Quataert, E.; Tatsuno, T.

    2009-04-23

    become the slow and entropy modes of the conventional MHD). In the "dissipation range" below ion gyroscale, there are again two cascades: the kinetic-Alfven-wave (KAW) cascade governed by two fluid-like Electron Reduced Magnetohydrodynamic (ERMHD) equations and a passive cascade of ion entropy fluctuations both in space and velocity. The latter cascade brings the energy of the inertial-range fluctuations that was Landau-damped at the ion gyroscale to collisional scales in the phase space and leads to ion heating. The KAWenergy is similarly damped at the electron gyroscale and converted into electron heat. Kolmogorov-style scaling relations are derived for all of these cascades. The relationship between the theoretical models proposed in this paper and astrophysical applications and observations is discussed in detail.

  4. Mount Rainier active cascade volcano

    Science.gov (United States)

    1994-01-01

    Mount Rainier is one of about two dozen active or recently active volcanoes in the Cascade Range, an arc of volcanoes in the northwestern United States and Canada. The volcano is located about 35 kilometers southeast of the Seattle-Tacoma metropolitan area, which has a population of more than 2.5 million. This metropolitan area is the high technology industrial center of the Pacific Northwest and one of the commercial aircraft manufacturing centers of the United States. The rivers draining the volcano empty into Puget Sound, which has two major shipping ports, and into the Columbia River, a major shipping lane and home to approximately a million people in southwestern Washington and northwestern Oregon. Mount Rainier is an active volcano. It last erupted approximately 150 years ago, and numerous large floods and debris flows have been generated on its slopes during this century. More than 100,000 people live on the extensive mudflow deposits that have filled the rivers and valleys draining the volcano during the past 10,000 years. A major volcanic eruption or debris flow could kill thousands of residents and cripple the economy of the Pacific Northwest. Despite the potential for such danger, Mount Rainier has received little study. Most of the geologic work on Mount Rainier was done more than two decades ago. Fundamental topics such as the development, history, and stability of the volcano are poorly understood.

  5. Electromagnetic Waves

    DEFF Research Database (Denmark)

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis...

  6. Dual Waves

    OpenAIRE

    Kallosh, Renata

    1994-01-01

    We study the gravitational waves in the 10-dimensional target space of the superstring theory. Some of these waves have unbroken supersymmetries. They consist of Brinkmann metric and of a 2-form field. Sigma-model duality is applied to such waves. The corresponding solutions we call dual partners of gravitational waves, or dual waves. Some of these dual waves upon Kaluza-Klein dimensional reduction to 4 dimensions become equivalent to the conformo-stationary solutions of axion-dilaton gravity...

  7. Resilience and Regime Shifts: Assessing Cascading Effects

    National Research Council Canada - National Science Library

    Kinzig, Ann P; Ryan, Paul; Etienne, Michel; Allison, Helen; Elmqvist, Thomas; Walker, Brian H

    2006-01-01

    .... "Cascading thresholds," i.e., the tendency of the crossing of one threshold to induce the crossing of other thresholds, often lead to very resilient, although often less desirable, alternative states.

  8. Substrate-emitting ring interband cascade lasers

    Science.gov (United States)

    Holzbauer, Martin; Szedlak, Rolf; Detz, Hermann; Weih, Robert; Höfling, Sven; Schrenk, Werner; Koeth, Johannes; Strasser, Gottfried

    2017-10-01

    We demonstrate interband cascade lasers fabricated into ring-shaped cavities with vertical light emission through the substrate at a wavelength of λ ≈ 3.7 μm. The out-coupling mechanism is based on a metallized second-order distributed feedback grating. At room-temperature, a pulsed threshold current-density of 0.75 kA/cm2 and a temperature-tuning rate of 0.3 nm/°C are measured. In contrast to the azimuthal polarization of ring quantum cascade lasers, we observe a radial polarization of the projected nearfield of ring interband cascade lasers. These findings underline the fundamental physical difference between light generation in interband and intersubband cascade lasers, offering new perspectives for device integration.

  9. Compression limits in cascaded quadratic soliton compression

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw

    2008-01-01

    Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency.......Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency....

  10. Cascade of links in complex networks

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yeqian; Sun, Bihui [Department of Management Science, School of Government, Beijing Normal University, 100875 Beijing (China); Zeng, An, E-mail: anzeng@bnu.edu.cn [School of Systems Science, Beijing Normal University, 100875 Beijing (China)

    2017-01-30

    Cascading failure is an important process which has been widely used to model catastrophic events such as blackouts and financial crisis in real systems. However, so far most of the studies in the literature focus on the cascading process on nodes, leaving the possibility of link cascade overlooked. In many real cases, the catastrophic events are actually formed by the successive disappearance of links. Examples exist in the financial systems where the firms and banks (i.e. nodes) still exist but many financial trades (i.e. links) are gone during the crisis, and the air transportation systems where the airports (i.e. nodes) are still functional but many airlines (i.e. links) stop operating during bad weather. In this letter, we develop a link cascade model in complex networks. With this model, we find that both artificial and real networks tend to collapse even if a few links are initially attacked. However, the link cascading process can be effectively terminated by setting a few strong nodes in the network which do not respond to any link reduction. Finally, a simulated annealing algorithm is used to optimize the location of these strong nodes, which significantly improves the robustness of the networks against the link cascade. - Highlights: • We propose a link cascade model in complex networks. • Both artificial and real networks tend to collapse even if a few links are initially attacked. • The link cascading process can be effectively terminated by setting a few strong nodes. • A simulated annealing algorithm is used to optimize the location of these strong nodes.

  11. Hot electron bolometer heterodyne receiver with a 4.7-THz quantum cascade laser as a local oscillator

    NARCIS (Netherlands)

    Kloosterman, J.L.; Hayton, D.J.; Ren, Y.; Kao, T.Y.; Hovenier, J.N.; Gao, J.R.; Klapwijk, T.M.; Hu, Q.; Walker, C.K.; Reno, J.L.

    2013-01-01

    We report on a heterodyne receiver designed to observe the astrophysically important neutral atomic oxygen [OI] line at 4.7448?THz. The local oscillator is a third-order distributed feedback quantum cascade laser operating in continuous wave mode at 4.741?THz. A quasi-optical, superconducting NbN

  12. Numerical optimization of multi-wavelength and cascaded Raman fiber lasers

    Science.gov (United States)

    Cierullies, Sven; Renner, Hagen; Brinkmeyer, Ernst

    2003-03-01

    We present a model for the simulation and optimization of Raman fiber lasers. Applications include cascaded Raman lasers as well as lasers running on several wavelengths within one Stokes band. The model takes into account forward and backward propagating waves as well as Raman induced interactions between all pump and Stokes lines. Example calculations for both the simulation of a laser and the optimization of the mirror reflectivities for maximum overall output power and equalized laser lines are performed.

  13. Design, Prototyping and Measurement of a Cascaded 6-GHz Frequency Selective Surface Array

    Directory of Open Access Journals (Sweden)

    Marcelo Bender Perotoni

    2016-04-01

    Full Text Available The design, prototyping, and free-space measurement of a 6-GHz Frequency Selective Surface filter is presented. The prototyping resolution of a large (A4 sheet size Frequency Selective Surface with small loops as elements is checked, as well as the correlation with measurements performed with a 3-D full-wave solver. The test also involved the effect of cascading two different Frequency Selective Surfaces with a viewpoint towards a narrower frequency range, which provided good results.

  14. Quantum cascade laser: Applications in chemical detection and environmental monitoring

    Directory of Open Access Journals (Sweden)

    Radovanović Jelena

    2009-01-01

    Full Text Available In this paper we consider the structural parameter optimization of the active region of a GaAs-based quantum cascade laser in order to maximize the optical gain of the laser at the characteristic wavelengths, which are best suited for detection of pollutant gasses, such as SO2, HNO3, CH4, and NH3, in the ambient air by means of direct absorption. The procedure relies on applying elaborate tools for global optimization, such as the genetic algorithm. One of the important goals is to extend the applicability of a single active region design to the detection of several compounds absorbing at close wave-lengths, and this is achieved by introducing a strong external magnetic field perpendicularly to the epitaxial layers. The field causes two-dimensional continuous energy subbands to split into the series of discrete Landau levels. Since the arrangement of Landau levels depends strongly on the magnitude of the magnetic field, this enables one to control the population inversion in the active region, and hence the optical gain. Furthermore, strong effects of band non-parabolicity result in subtle changes of the lasing wavelength at magnetic fields which maximize the gain, thus providing a path for fine-tuning of the output radiation properties and changing the target compound for detection. The numerical results are presented for quantum cascade laser structures designed to emit at specified wavelengths in the mid-infrared part of the spectrum.

  15. Cascades and statistical equilibrium in shell models of turbulence

    CERN Document Server

    Ditlevsen, P D

    1996-01-01

    We study the GOY shell model simulating the cascade processes of turbulent flow. The model has two inviscid invariants governing the dynamical behavior. Depending on the choice of interaction coefficients, or coupling parameters, the two invariants are either both positive definite, analogous to energy and enstrophy of 2D flow, or only one is positive definite and the other not, analogous to energy and helicity of 3D flow. In the 2D like model the dynamics depend on the spectral ratio of enstrophy to energy. That ratio depends on wave-number as $k^{\\alpha}$. The enstrophy transfer through the inertial sub-range can be described as a forward cascade for $\\alpha 2$. The $\\alpha =2$ case, corresponding to 2D turbulence, is a borderline between the two descriptions. The difference can be understood in terms of the ratio of typical timescales in the inertial sub-range and in the viscous sub-range. The multi fractality of the enstrophy dissipation also depends on the parameter $\\alpha$, and seems to be related to ...

  16. Terahertz Quantum Cascade Laser With Efficient Coupling and Beam Profile

    Science.gov (United States)

    Chattopadhyay, Goutam; Kawamura, Jonathan H.; Lin, Robert H.; Williams, Benjamin

    2012-01-01

    Quantum cascade lasers (QCLs) are unipolar semiconductor lasers, where the wavelength of emitted radiation is determined by the engineering of quantum states within the conduction band in coupled multiple-quantum-well heterostructures to have the desired energy separation. The recent development of terahertz QCLs has provided a new generation of solid-state sources for radiation in the terahertz frequency range. Terahertz QCLs have been demonstrated from 0.84 to 5.0 THz both in pulsed mode and continuous wave mode (CW mode). The approach employs a resonant-phonon depopulation concept. The metal-metal (MM) waveguide fabrication is performed using Cu-Cu thermo-compression bonding to bond the GaAs/AlGaAs epitaxial layer to a GaAs receptor wafer.

  17. SUBJECT INDEX

    Indian Academy of Sciences (India)

    179. Arabian Sea. Improved bathymetric datasets for the shallow water regions in the Indian Ocean. 261. Vertical propagation of baroclinic Kelvin waves along the west coast of India. 331. Arabian Sea Monsoon Experiment (ARMEX). Surface and upper air meteorological features during onset phase of 2003 monsoon. 305.

  18. New quantum cascade laser sources for sensing applications (Conference Presentation)

    Science.gov (United States)

    Troccoli, Mariano

    2017-05-01

    In this presentation we will review our most recent results on development of Quantum Cascade Lasers (QCLs) for analytical and industrial applications. QCLs have demonstrated the capability to cover the entire range of Mid-IR, Far-IR, and THz wavelengths by skillful tuning of the material design and composition and by use of intrinsic material properties via a set of techniques collectively called "bandgap engineering". The use of MOCVD, pioneered on industrial scale by AdTech Optics, has enabled the deployment of QCL devices into a diverse range of environments and applications. QCLs can be tailored to the specific application requirements due to their unprecedented flexibility in design and thanks to the leveraging of well-known III-V fabrication technologies inherited from the NIR domain. Nevertheless, several applications and new frontiers in R and D need the constant support of new developments in device features, capabilities, and performances. We have developed a wide range of devices, from high power, high efficiency multi-mode sources, to narrow-band, single mode devices with low-power consumption, and from non-linear, multi-wavelength generating devices to broadband sources and multi-emitter arrays. All our devices are grown and processed using MOCVD technology and allow us to attain competitive performances across the whole mid-IR spectral range. This talk will present an overview of our current achievements. References 1. M. Troccoli, "High power emission and single mode operation of quantum cascade lasers for industrial applications", J. Sel. Topics in Quantum Electron., 21 (6), 1-7 (2015). Invited Review. 2. Seungyong Jung, Aiting Jiang, Yifan Jiang, Karun Vijayraghavan, Xiaojun Wang, Mariano Troccoli, and Mikhail A. Belkin, "Broadly Tunable Monolithic Terahertz Quantum Cascade Laser Sources", Nature Comm. 5, 4267 (2014).. 3. Mariano Troccoli, Arkadiy Lyakh, Jenyu Fan, Xiaojun Wang, Richard Maulini, Alexei G Tsekoun, Rowel Go, C Kumar N Patel, "Long-Wave

  19. Robustness of localized DNA strand displacement cascades.

    Science.gov (United States)

    Teichmann, Mario; Kopperger, Enzo; Simmel, Friedrich C

    2014-08-26

    Colocalization can strongly alter the kinetics and efficiency of chemical processes. For instance, in DNA-templated synthesis unfavorable reactions are sped up by placing reactants into close proximity onto a DNA scaffold. In biochemistry, clustering of enzymes has been demonstrated to enhance the reaction flux through some enzymatic cascades. Here we investigate the effect of colocalization on the performance of DNA strand displacement (DSD) reactions, an important class of reactions utilized in dynamic DNA nanotechnology. We study colocalization by immobilizing a two-stage DSD reaction cascade comprised of a “sender” and a “receiver” gate onto a DNA origami platform. The addition of a DNA (or RNA) input strand displaces a signal strand from the sender gate, which can then transfer to the receiver gate. The performance of the cascade is found to vary strongly with the distance between the gates. A cascade with an intermediate gate distance of ≈20 nm exhibits faster kinetics than those with larger distances, whereas a cascade with smaller distance is corrupted by excessive intraorigami leak reactions. The 20 nm cascade is found to be considerably more robust with respect to a competing reaction, and implementation of multiple receiver gates further increases this robustness. Our results indicate that for the 20 nm distance a fraction of signal strands is transferred locally to a receiver gate on the same platform, probably involving direct physical contact between the gates. The performance of the cascade is consistent with a simple model that takes “local” and “global” transfer processes into account.

  20. An Analysis of Shot Noise Propagation and Amplificationin Harmonic Cascade FELs

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z.; /SLAC

    2006-12-11

    The harmonic generation process in a harmonic cascade (HC) FEL is subject to noise degradation which is proportional to the square of the total harmonic order. In this paper, we study the shot noise evolution in the first-stage modulator and radiator of a HC FEL that produces the dominant noise contributions. We derive the effective input noise for a modulator operating in the low-gain regime, and analyze the radiator noise for a density-modulated beam. The significance of these noise sources in different harmonic cascade designs is also discussed.

  1. Expanding subjectivities

    DEFF Research Database (Denmark)

    Lundgaard Andersen, Linda; Soldz, Stephen

    2012-01-01

    A major theme in recent psychoanalytic thinking concerns the use of therapist subjectivity, especially “countertransference,” in understanding patients. This thinking converges with and expands developments in qualitative research regarding the use of researcher subjectivity as a tool to understa...

  2. MAP kinase cascades in Arabidopsis innate immunity

    DEFF Research Database (Denmark)

    Rasmussen, Magnus Wohlfahrt; Roux, Milena Edna; Petersen, Morten

    2012-01-01

    Plant mitogen-activated protein kinase (MAPK) cascades generally transduce extracellular stimuli into cellular responses. These stimuli include the perception of pathogen-associated molecular patterns (PAMPs) by host transmembrane pattern recognition receptors which trigger MAPK-dependent innate...... immune responses. In the model Arabidopsis, molecular genetic evidence implicates a number of MAPK cascade components in PAMP signaling, and in responses to immunity-related phytohormones such as ethylene, jasmonate, and salicylate. In a few cases, cascade components have been directly linked...... to the transcription of target genes or to the regulation of phytohormone synthesis. Thus MAPKs are obvious targets for bacterial effector proteins and are likely guardees of resistance proteins, which mediate defense signaling in response to the action of effectors, or effector-triggered immunity. This mini...

  3. Bifurcations analysis of turbulent energy cascade

    Energy Technology Data Exchange (ETDEWEB)

    Divitiis, Nicola de, E-mail: n.dedivitiis@gmail.com

    2015-03-15

    This note studies the mechanism of turbulent energy cascade through an opportune bifurcations analysis of the Navier–Stokes equations, and furnishes explanations on the more significant characteristics of the turbulence. A statistical bifurcations property of the Navier–Stokes equations in fully developed turbulence is proposed, and a spatial representation of the bifurcations is presented, which is based on a proper definition of the fixed points of the velocity field. The analysis first shows that the local deformation can be much more rapid than the fluid state variables, then explains the mechanism of energy cascade through the aforementioned property of the bifurcations, and gives reasonable argumentation of the fact that the bifurcations cascade can be expressed in terms of length scales. Furthermore, the study analyzes the characteristic length scales at the transition through global properties of the bifurcations, and estimates the order of magnitude of the critical Taylor-scale Reynolds number and the number of bifurcations at the onset of turbulence.

  4. Seeded QED cascades in counterpropagating laser pulses.

    Science.gov (United States)

    Grismayer, T; Vranic, M; Martins, J L; Fonseca, R A; Silva, L O

    2017-02-01

    The growth rates of seeded QED cascades in counterpropagating lasers are calculated with first-principles two- and three-dimensional QED-PIC (particle-in-cell) simulations. The dependence of the growth rate on the laser polarization and intensity is compared with analytical models that support the findings of the simulations. The models provide insight regarding the qualitative trend of the cascade growth when the intensity of the laser field is varied. A discussion about the cascade's threshold is included, based on the analytical and numerical results. These results show that relativistic pair plasmas and efficient conversion from laser photons to γ rays can be observed with the typical intensities planned to operate on future ultraintense laser facilities such as ELI or Vulcan.

  5. Emergence of event cascades in inhomogeneous networks

    CERN Document Server

    Onaga, Tomokatsu

    2016-01-01

    There is a commonality among contagious diseases, tweets, urban crimes, nuclear reactions, and neuronal firings that past events facilitate the future occurrence of events. The spread of events has been extensively studied such that the systems exhibit catastrophic chain reactions if the interaction represented by the ratio of reproduction exceeds unity; however, their subthreshold states for the case of the weaker interaction are not fully understood. Here, we report that these systems are possessed by nonstationary cascades of event-occurrences already in the subthreshold regime. Event cascades can be harmful in some contexts, when the peak-demand causes vaccine shortages, heavy traffic on communication lines, frequent crimes, or large fluctuations in nuclear reactions, but may be beneficial in other contexts, such that spontaneous activity in neural networks may be used to generate motion or store memory. Thus it is important to comprehend the mechanism by which such cascades appear, and consider controlli...

  6. Epidemic and Cascading Survivability of Complex Networks

    DEFF Research Database (Denmark)

    Manzano, Marc; Calle, Eusebi; Ripoll, Jordi

    2014-01-01

    Our society nowadays is governed by complex networks, examples being the power grids, telecommunication networks, biological networks, and social networks. It has become of paramount importance to understand and characterize the dynamic events (e.g. failures) that might happen in these complex...... networks. For this reason, in this paper, we propose two measures to evaluate the vulnerability of complex networks in two different dynamic multiple failure scenarios: epidemic-like and cascading failures. Firstly, we present epidemic survivability ( ES ), a new network measure that describes...... the vulnerability of each node of a network under a specific epidemic intensity. Secondly, we propose cascading survivability ( CS ), which characterizes how potentially injurious a node is according to a cascading failure scenario. Then, we show that by using the distribution of values obtained from ES and CS...

  7. Epidemic and Cascading Survivability of Complex Networks

    CERN Document Server

    Manzano, Marc; Ripoll, Jordi; Fagertun, Anna Manolova; Torres-Padrosa, Victor; Pahwa, Sakshi; Scoglio, Caterina

    2014-01-01

    Our society nowadays is governed by complex networks, examples being the power grids, telecommunication networks, biological networks, and social networks. It has become of paramount importance to understand and characterize the dynamic events (e.g. failures) that might happen in these complex networks. For this reason, in this paper, we propose two measures to evaluate the vulnerability of complex networks in two different dynamic multiple failure scenarios: epidemic-like and cascading failures. Firstly, we present \\emph{epidemic survivability} ($ES$), a new network measure that describes the vulnerability of each node of a network under a specific epidemic intensity. Secondly, we propose \\emph{cascading survivability} ($CS$), which characterizes how potentially injurious a node is according to a cascading failure scenario. Then, we show that by using the distribution of values obtained from $ES$ and $CS$ it is possible to describe the vulnerability of a given network. We consider a set of 17 different compl...

  8. Plasma waves

    CERN Document Server

    Swanson, DG

    1989-01-01

    Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th

  9. Piscivores, Trophic Cascades, and Lake Management

    Directory of Open Access Journals (Sweden)

    Ray W. Drenner

    2002-01-01

    Full Text Available The concept of cascading trophic interactions predicts that an increase in piscivore biomass in lakes will result in decreased planktivorous fish biomass, increased herbivorous zooplankton biomass, and decreased phytoplankton biomass. Though often accepted as a paradigm in the ecological literature and adopted by lake managers as a basis for lake management strategies, the trophic cascading interactions hypothesis has not received the unequivocal support (in the form of rigorous experimental testing that might be expected of a paradigm. Here we review field experiments and surveys, testing the hypothesis that effects of increasing piscivore biomass will cascade down through the food web yielding a decline in phytoplankton biomass. We found 39 studies in the scientific literature examining piscivore effects on phytoplankton biomass. Of the studies, 22 were confounded by supplemental manipulations (e.g., simultaneous reduction of nutrients or removal of planktivores and could not be used to assess piscivore effects. Of the 17 nonconfounded studies, most did not find piscivore effects on phytoplankton biomass and therefore did not support the trophic cascading interactions hypothesis. However, the trophic cascading interactions hypothesis also predicts that lake systems containing piscivores will have lower phytoplankton biomass for any given phosphorus concentration. Based on regression analyses of chlorophyll�total phosphorus relationships in the 17 nonconfounded piscivore studies, this aspect of the trophic cascading interactions hypothesis was supported. The slope of the chlorophyll vs. total phosphorus regression was lower in lakes with planktivores and piscivores compared with lakes containing only planktivores but no piscivores. We hypothesize that this slope can be used as an indicator of “functional piscivory” and that communities with extremes of functional piscivory (zero and very high represent classical 3- and 4-trophic level

  10. Turbulence of Weak Gravitational Waves in the Early Universe

    Science.gov (United States)

    Galtier, Sébastien; Nazarenko, Sergey V.

    2017-12-01

    We study the statistical properties of an ensemble of weak gravitational waves interacting nonlinearly in a flat space-time. We show that the resonant three-wave interactions are absent and develop a theory for four-wave interactions in the reduced case of a 2.5 +1 diagonal metric tensor. In this limit, where only plus-polarized gravitational waves are present, we derive the interaction Hamiltonian and consider the asymptotic regime of weak gravitational wave turbulence. Both direct and inverse cascades are found for the energy and the wave action, respectively, and the corresponding wave spectra are derived. The inverse cascade is characterized by a finite-time propagation of the metric excitations—a process similar to an explosive nonequilibrium Bose-Einstein condensation, which provides an efficient mechanism to ironing out small-scale inhomogeneities. The direct cascade leads to an accumulation of the radiation energy in the system. These processes might be important for understanding the early Universe where a background of weak nonlinear gravitational waves is expected.

  11. Turbulence of Weak Gravitational Waves in the Early Universe.

    Science.gov (United States)

    Galtier, Sébastien; Nazarenko, Sergey V

    2017-12-01

    We study the statistical properties of an ensemble of weak gravitational waves interacting nonlinearly in a flat space-time. We show that the resonant three-wave interactions are absent and develop a theory for four-wave interactions in the reduced case of a 2.5+1 diagonal metric tensor. In this limit, where only plus-polarized gravitational waves are present, we derive the interaction Hamiltonian and consider the asymptotic regime of weak gravitational wave turbulence. Both direct and inverse cascades are found for the energy and the wave action, respectively, and the corresponding wave spectra are derived. The inverse cascade is characterized by a finite-time propagation of the metric excitations-a process similar to an explosive nonequilibrium Bose-Einstein condensation, which provides an efficient mechanism to ironing out small-scale inhomogeneities. The direct cascade leads to an accumulation of the radiation energy in the system. These processes might be important for understanding the early Universe where a background of weak nonlinear gravitational waves is expected.

  12. Volcano geodesy in the Cascade arc, USA

    Science.gov (United States)

    Poland, Michael; Lisowski, Michael; Dzurisin, Daniel; Kramer, Rebecca; McLay, Megan; Pauk, Benjamin

    2017-01-01

    Experience during historical time throughout the Cascade arc and the lack of deep-seated deformation prior to the two most recent eruptions of Mount St. Helens might lead one to infer that Cascade volcanoes are generally quiescent and, specifically, show no signs of geodetic change until they are about to erupt. Several decades of geodetic data, however, tell a different story. Ground- and space-based deformation studies have identified surface displacements at five of the 13 major Cascade arc volcanoes that lie in the USA (Mount Baker, Mount St. Helens, South Sister, Medicine Lake, and Lassen volcanic center). No deformation has been detected at five volcanoes (Mount Rainier, Mount Hood, Newberry Volcano, Crater Lake, and Mount Shasta), and there are not sufficient data at the remaining three (Glacier Peak, Mount Adams, and Mount Jefferson) for a rigorous assessment. In addition, gravity change has been measured at two of the three locations where surveys have been repeated (Mount St. Helens and Mount Baker show changes, while South Sister does not). Broad deformation patterns associated with heavily forested and ice-clad Cascade volcanoes are generally characterized by low displacement rates, in the range of millimeters to a few centimeters per year, and are overprinted by larger tectonic motions of several centimeters per year. Continuous GPS is therefore the best means of tracking temporal changes in deformation of Cascade volcanoes and also for characterizing tectonic signals so that they may be distinguished from volcanic sources. Better spatial resolution of volcano deformation can be obtained through the use of campaign GPS, semipermanent GPS, and interferometric synthetic aperture radar observations, which leverage the accumulation of displacements over time to improve signal to noise. Deformation source mechanisms in the Cascades are diverse and include magma accumulation and withdrawal, post-emplacement cooling of recent volcanic deposits, magmatic

  13. Cascade morphology transition in bcc metals.

    Science.gov (United States)

    Setyawan, Wahyu; Selby, Aaron P; Juslin, Niklas; Stoller, Roger E; Wirth, Brian D; Kurtz, Richard J

    2015-06-10

    Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent, b, in the defect production curve as a function of cascade energy (N(F) ~ E(MD)(b)). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, μ, between the high- and the low-energy regime. Using Cr, Fe, Mo and W data, an empirical formula of μ as a function of displacement threshold energy, E(d), is presented for bcc metals.

  14. Cascade morphology transition in bcc metals

    OpenAIRE

    Setyawan, Wahyu; Selby, Aaron P.; Juslin, Niklas; Stoller, Roger E; Wirth, Brian D.; Kurtz, Richard J.

    2014-01-01

    Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent, $b$, in the defect production curve as a function of cascade energy ($N_F \\sim E_{MD}^b$). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, $\\mu$, between the high- and the l...

  15. Robustness of networks against cascading failures

    Science.gov (United States)

    Dou, Bing-Lin; Wang, Xue-Guang; Zhang, Shi-Yong

    2010-06-01

    Inspired by other related works, this paper proposes a non-linear load-capacity model against cascading failures, which is more suitable for real networks. The simulation was executed on the B-A scale-free network, E-R random network, Internet AS level network, and the power grid of the western United States. The results show that the model is feasible and effective. By studying the relationship between network cost and robustness, we find that the model can defend against cascading failures better and requires a lower investment cost when higher robustness is required.

  16. Robustness of network controllability in cascading failure

    Science.gov (United States)

    Chen, Shi-Ming; Xu, Yun-Fei; Nie, Sen

    2017-04-01

    It is demonstrated that controlling complex networks in practice needs more inputs than that predicted by the structural controllability framework. Besides, considering the networks usually faces to the external or internal failure, we define parameters to evaluate the control cost and the variation of controllability after cascades, exploring the effect of number of control inputs on the controllability for random networks and scale-free networks in the process of cascading failure. For different topological networks, the results show that the robustness of controllability will be stronger through allocating different control inputs and edge capacity.

  17. Volcano geodesy in the Cascade arc, USA

    Science.gov (United States)

    Poland, Michael P.; Lisowski, Michael; Dzurisin, Daniel; Kramer, Rebecca; McLay, Megan; Pauk, Ben

    2017-08-01

    Experience during historical time throughout the Cascade arc and the lack of deep-seated deformation prior to the two most recent eruptions of Mount St. Helens might lead one to infer that Cascade volcanoes are generally quiescent and, specifically, show no signs of geodetic change until they are about to erupt. Several decades of geodetic data, however, tell a different story. Ground- and space-based deformation studies have identified surface displacements at five of the 13 major Cascade arc volcanoes that lie in the USA (Mount Baker, Mount St. Helens, South Sister, Medicine Lake, and Lassen volcanic center). No deformation has been detected at five volcanoes (Mount Rainier, Mount Hood, Newberry Volcano, Crater Lake, and Mount Shasta), and there are not sufficient data at the remaining three (Glacier Peak, Mount Adams, and Mount Jefferson) for a rigorous assessment. In addition, gravity change has been measured at two of the three locations where surveys have been repeated (Mount St. Helens and Mount Baker show changes, while South Sister does not). Broad deformation patterns associated with heavily forested and ice-clad Cascade volcanoes are generally characterized by low displacement rates, in the range of millimeters to a few centimeters per year, and are overprinted by larger tectonic motions of several centimeters per year. Continuous GPS is therefore the best means of tracking temporal changes in deformation of Cascade volcanoes and also for characterizing tectonic signals so that they may be distinguished from volcanic sources. Better spatial resolution of volcano deformation can be obtained through the use of campaign GPS, semipermanent GPS, and interferometric synthetic aperture radar observations, which leverage the accumulation of displacements over time to improve signal to noise. Deformation source mechanisms in the Cascades are diverse and include magma accumulation and withdrawal, post-emplacement cooling of recent volcanic deposits, magmatic

  18. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....

  19. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and ... having trouble with the heat. If a heat wave is predicted or happening… - Slow down. Avoid strenuous ...

  20. Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, H. C.

    1998-01-01

    This paper concerns with the development of the wave energy converter (WEC) Wave Dragon. This WEC is based on the overtopping principle. An overview of the performed research done concerning the Wave Dragon over the past years is given, and the results of one of the more comprehensive studies......, concerning a hydraulic evaluation and optimisation of the geometry of the Wave Dragon, is presented. Furthermore, the plans for the future development projects are sketched....

  1. Gravitational Waves

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Jonah Maxwell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-18

    This report has slides on Gravitational Waves; Pound and Rebka: A Shocking Fact; Light is a Ruler; Gravity is the Curvature of Spacetime; Gravitational Waves Made Simple; How a Gravitational Wave Affects Stuff Here; LIGO; This Detection: Neutron Stars; What the Gravitational Wave Looks Like; The Sound of Merging Neutron Stars; Neutron Star Mergers: More than GWs; The Radioactive Cloud; The Kilonova; and finally Summary, Multimessenger Astronomy.

  2. The Role Of Torsional Alfvén Waves in Coronal Heating

    Science.gov (United States)

    Antolin, P.; Shibata, K.

    2010-03-01

    In the context of coronal heating, among the zoo of magnetohydrodynamic (MHD) waves that exist in the solar atmosphere, Alfvén waves receive special attention. Indeed, these waves constitute an attractive heating agent due to their ability to carry over the many different layers of the solar atmosphere sufficient energy to heat and maintain a corona. However, due to their incompressible nature these waves need a mechanism such as mode conversion (leading to shock heating), phase mixing, resonant absorption, or turbulent cascade in order to heat the plasma. Furthermore, their incompressibility makes their detection in the solar atmosphere very difficult. New observations with polarimetric, spectroscopic, and imaging instruments such as those on board the Japanese satellite Hinode, or the Crisp spectropolarimeter of the Swedish Solar Telescope or the Coronal Multi-channel Polarimeter, are bringing strong evidence for the existence of energetic Alfvén waves in the solar corona. In order to assess the role of Alfvén waves in coronal heating, in this work we model a magnetic flux tube being subject to Alfvén wave heating through the mode conversion mechanism. Using a 1.5 dimensional MHD code, we carry out a parameter survey varying the magnetic flux tube geometry (length and expansion), the photospheric magnetic field, the photospheric velocity amplitudes, and the nature of the waves (monochromatic or white-noise spectrum). The regimes under which Alfvén wave heating produces hot and stable coronae are found to be rather narrow. Independently of the photospheric wave amplitude and magnetic field, a corona can be produced and maintained only for long (>80 Mm) and thick (area ratio between the photosphere and corona >500) loops. Above a critical value of the photospheric velocity amplitude (generally a few km s-1) the corona can no longer be maintained over extended periods of time and collapses due to the large momentum of the waves. These results establish several

  3. Electromagnetic Waves

    OpenAIRE

    Blok, H.; van den Berg, P.M.

    2011-01-01

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis, material characterization, electromagnetic properties of plasma, analysis and applications of periodic structures and waveguide components, etc.

  4. Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter; Knapp, W.

    2006-01-01

    Wave Dragon is a floating wave energy converter working by extracting energy principally by means of overtopping of waves into a reservoir. A 1:4.5 scale prototype has been sea tested for 20 months. This paper presents results from testing, experiences gained and developments made during...

  5. Wave phenomena

    CERN Document Server

    Towne, Dudley H

    1988-01-01

    This excellent undergraduate-level text emphasizes optics and acoustics, covering inductive derivation of the equation for transverse waves on a string, acoustic plane waves, boundary-value problems, polarization, three-dimensional waves and more. With numerous problems (solutions for about half). ""The material is superbly chosen and brilliantly written"" - Physics Today. Problems. Appendices.

  6. Developmental cascade models linking peer victimization, depression, and academic achievement in Chinese children.

    Science.gov (United States)

    Liu, Junsheng; Bullock, Amanda; Coplan, Robert J; Chen, Xinyin; Li, Dan; Zhou, Ying

    2017-10-04

    This study explored the longitudinal relations among peer victimization, depression, and academic achievement in Chinese primary school students. Participants were N = 945 fourth-grade students (485 boys, 460 girls; Mage  = 10.16 years, SD = 2 months) attending elementary schools in Shanghai, People's Republic of China. Three waves of data on peer victimization, depression, and academic achievement were collected from peer nominations, self-reports, and school records, respectively. The results indicated that peer victimization had both direct and indirect effects on later depression and academic achievement. Depression also had both direct and indirect negative effects on later academic achievement, but demonstrated only an indirect effect on later peer victimization. Finally, academic achievement had both direct and indirect negative effects on later peer victimization and depression. The findings show that there are cross-cultural similarities and differences in the various transactions that exist among peer victimization, depression, and academic achievement. Statement of contribution What is already known on this subject? Peer victimization directly and indirectly relates to depression and academic achievement. Depression directly and indirectly relates to academic achievement. Academic achievement directly and indirectly relates to depression. What the present study adds? A developmental cascade approach was used to assess the interrelations among peer victimization, depression, and academic achievement. Academic achievement mediates the relation between peer victimization and depression. Depression is related to peer victimization through academic achievement. Academic achievement directly and indirectly relates to peer victimization. Academic achievement is related to depression through peer victimization. © 2017 The British Psychological Society.

  7. Gene regulation by MAP kinase cascades

    DEFF Research Database (Denmark)

    Fiil, Berthe Katrine; Petersen, Klaus; Petersen, Morten

    2009-01-01

    Mitogen-activated protein kinase (MAPK) cascades are signaling modules that transduce extracellular stimuli to a range of cellular responses. Research in yeast and metazoans has shown that MAPK-mediated phosphorylation directly or indirectly regulates the activity of transcription factors. Plant ...... gene expression....

  8. Multilevel Inverter by Cascading Industrial VSI

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede; Pedersen, John Kim

    2002-01-01

    by a standard triphase IGBT inverter module. Thus, a high fault tolerance is being achieved and the output transformer requirement is eliminated. A staggered space-vector modulation technique applicable to three-phase cascaded voltage-source inverter topologies is also demonstrated. Both computer simulations...

  9. Criticality in a cascading failure blackout model

    Energy Technology Data Exchange (ETDEWEB)

    Nedic, Dusko P.; Kirschen, Daniel S. [University of Manchester (United Kingdom). School of Electrical and Electronic Engineering; Dobson, Ian [University of Wisconsin, Madison, WI (United States). ECE Department; Carreras, Benjamin A.; Lynch, Vickie E. [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2006-11-15

    We verify and examine criticality in a 1000 bus network with an AC blackout model that represents many of the interactions that occur in cascading failure. At the critical loading there is a sharp rise in the mean blackout size and a power law probability distribution of blackout size that indicates a significant risk of large blackouts. (author)

  10. Geothermal research, Oregon Cascades: Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Priest, G.R.; Black, G.L.

    1988-10-27

    Previous USDOE-funded geothermal studies have produced an extensive temperature gradient and heat flow data base for the State of Oregon. One of the important features identified as a result of these studies is a rapid transition from heat flow values on the order of 40 mW/m/sup 2/ in the Willamette Valley and Western Cascades to values of greater than or equal to100 mW/m/sup 2/ in the High Cascades and the eastern portion of the Western Cascades. These data indicate that the Cascade Range in Oregon has potential as a major geothermal province and stimulated much of the later work completed by government agencies and private industry. Additional data generated as a result of this grant and published in DOGAMI Open-File Report 0-86-2 further define the location and magnitude of this transition zone. In addition, abundant data collected from the vicinity of Breitenbush and Austin Hot Springs have permitted the formulation of relatively detailed models of these hydrothermal systems. These models are published in DOGAMI Open-File Report 0-88-5. Task 1.2 of the Deliverables section of Amendment M001 is fulfilled by DOGAMI publication GMS-48, Geologic map of the McKenzie Bridge quadrangle, Lane County, Oregon. This map was printed in October, 1988, and is part of the final submission to USDOE. 8 refs.

  11. The Attention Cascade Model and Attentional Blink

    Science.gov (United States)

    Shih, Shui-I

    2008-01-01

    An attention cascade model is proposed to account for attentional blinks in rapid serial visual presentation (RSVP) of stimuli. Data were collected using single characters in a single RSVP stream at 10 Hz [Shih, S., & Reeves, A. (2007). "Attentional capture in rapid serial visual presentation." "Spatial Vision", 20(4), 301-315], and single words,…

  12. Quantum Cascade Lasers in Biomedical Infrared Imaging.

    Science.gov (United States)

    Bird, Benjamin; Baker, Matthew J

    2015-10-01

    Technological advances, namely the integration of quantum cascade lasers (QCLs) within an infrared (IR) microscope, are enabling the development of valuable label-free biomedical-imaging tools capable of targeting and detecting salient chemical species within practical clinical timeframes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Nonconforming finite elements and the Cascade iteration

    NARCIS (Netherlands)

    Stevenson, R.

    1999-01-01

    We derive sucient conditions under which the Cascade iteration applied to nonconforming nite element discretizations yields an optimal solver. Key ingredients are optimal error estimates of such discretizations, which we therefore study in detail. We derive a new, ecient modied Morley nite element

  14. Cascade Training and Teachers' Professional Development.

    Science.gov (United States)

    Hayes, David

    2000-01-01

    Examines the experience of a nationwide inservice teacher development project in Sri Lanka that aims to remedy the potential deficiencies of cascade models of teacher development. Shows how project training and development strategies that are context sensitive, collaborative, and reflexive seek to involve teachers in managing their own…

  15. Cascading effects of overfishing marine systems

    NARCIS (Netherlands)

    Scheffer, M.; Carpenter, S.; Young, de B.

    2005-01-01

    Profound indirect ecosystem effects of overfishing have been shown for coastal systems such as coral reefs and kelp forests. A new study from the ecosystem off the Canadian east coast now reveals that the elimination of large predatory fish can also cause marked cascading effects on the pelagic food

  16. Modeling and simulation of cascading contingencies

    Science.gov (United States)

    Zhang, Jianfeng

    This dissertation proposes a new approach to model and study cascading contingencies in large power systems. The most important contribution of the work involves the development and validation of a heuristic analytic model to assess the likelihood of cascading contingencies, and the development and validation of a uniform search strategy. We model the probability of cascading contingencies as a function of power flow and power flow changes. Utilizing logistic regression, the proposed model is calibrated using real industry data. This dissertation analyzes random search strategies for Monte Carlo simulations and proposes a new uniform search strategy based on the Metropolis-Hastings Algorithm. The proposed search strategy is capable of selecting the most significant cascading contingencies, and it is capable of constructing an unbiased estimator to provide a measure of system security. This dissertation makes it possible to reasonably quantify system security and justify security operations when economic concerns conflict with reliability concerns in the new competitive power market environment. It can also provide guidance to system operators about actions that may be taken to reduce the risk of major system blackouts. Various applications can be developed to take advantage of the quantitative security measures provided in this dissertation.

  17. Cascade theory in isotopic separation processes; Theorie des cascades en separation isotopique

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, J.P.

    1994-06-01

    Three main areas are developed within the scope of this work: - the first one is devoted to fundamentals: separative power, value function, ideal cascade and square cascade. Applications to two main cases are carried out, namely: Study of binary isotopic mix, Study of processes with a small enrichment coefficient. - The second one is devoted to cascade coupling -high-flux coupling (more widely used and better known) as well as low-flux coupling are presented and compared to one another. - The third one is an outlook on problems linked to cascade transients. Those problem are somewhat intricate and their interest lies mainly into two areas: economics where the start-up time may have a large influence on the interests paid during the construction and start-up period, military productions where the start-up time has a direct bearing on the production schedule. (author). 50 figs. 3 annexes. 12 refs. 6 tabs.

  18. Higher-order Kerr effect and harmonic cascading in gases

    OpenAIRE

    Bache, Morten; Eilenberger, Falk; Minardi, Stefano

    2012-01-01

    The higher-order Kerr effect (HOKE) has recently been advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth-order nonlinearity that is negative and significant. Higher-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths, cascading increases the HOKE sat...

  19. A Modeling Framework for System Restoration from Cascading Failures

    OpenAIRE

    Chaoran Liu; Daqing Li; Enrico Zio; Rui Kang

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling f...

  20. Exploring cascading outages and weather via processing historic data

    OpenAIRE

    Dobson, Ian; Carrington, NichelleLe K.; Zhou, Kai; Wang, Zhaoyu; Carreras, Benjamin A.; Reynolds-Barredo, Jose M.

    2017-01-01

    We describe some bulk statistics of historical initial line outages and the implications for forming contingency lists and understanding which initial outages are likely to lead to further cascading. We use historical outage data to estimate the effect of weather on cascading via cause codes and via NOAA storm data. Bad weather significantly increases outage rates and interacts with cascading effects, and should be accounted for in cascading models and simulations. We suggest how weather effe...

  1. Acoustics waves and oscillations

    CERN Document Server

    Sen, S.N.

    2013-01-01

    Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...

  2. SUBJECT INDEX

    Indian Academy of Sciences (India)

    Subject Index. Variation of surface electric field during geomagnetic disturbed period at Maitri, Antarctica. 1721. Geomorphology. A simple depression-filling method for raster and irregular elevation datasets. 1653. Decision Support System integrated with Geographic. Information System to target restoration actions in water-.

  3. Calculation of transonic flow in radial turbine blade cascade

    Science.gov (United States)

    Petr, Straka

    2017-09-01

    Numerical modeling of transonic centripetal turbulent flow in radial blade cascade is described in this paper. Attention is paid to effect of the outlet confusor on flow through the radial blade cascade. Parameters of presented radial blade cascade are compared with its linear representation

  4. Hollow Anode Cascading Plasma Focus | Alabraba | Journal of the ...

    African Journals Online (AJOL)

    Journal of the Nigerian Association of Mathematical Physics ... Using the 3-phase model for each focus event, the 9-phase, two solid disc auxiliary anode cascading plasma focus has been extended to include holes at the center of each cascade anode (hereafter referred to as hollow anode cascading focus) with a view of ...

  5. Assessment of resting electrocardiogram, P wave dispersion and duration in different genders applying for registration to the School of Physical Education and Sports - results of a single centre Turkish Trial with 2093 healthy subjects.

    Science.gov (United States)

    Yildiz, Mustafa; Aygin, Dilek; Pazarli, Pinar; Sayan, Ayse; Semiz, Olcay; Kahyaoglu, Osman; Yildiz, Banu S; Hasdemir, Hakan; Akin, Ibrahim; Keser, Nurgul; Altinkaynak, Sevin

    2011-10-01

    The 12-lead electrocardiogram shows a broad range of abnormal patterns in trained athletes. The primary end point of this study was to investigate P wave dispersion, and P wave durations and related factors in different genders applying for registration to the School of Physical Education and Sports. From 2006 to 2009, a total of 2093 students - 1674 boys with a mean age of 19.8 plus or minus 1.9 years and 419 girls with a mean age of 19.1 plus or minus 1.8 years - were included in the study. All 12 leads of the resting electrocardiogram were evaluated for P wave dispersion and electrocardiogram abnormalities. Baseline parameters such as age, body weight, body height, and body mass index, as well as electrocardiogram findings such as P wave maximal duration and P wave dispersion, were significantly higher in boys than in girls. Of all the parameters tested with correlation analysis, only gender (p = 0.03) (r = 0.04), body weight (p gender, body weight, body height, and body mass index.

  6. LANGMUIR WAVE DECAY IN INHOMOGENEOUS SOLAR WIND PLASMAS: SIMULATION RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Krafft, C. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, F-91128 Palaiseau Cedex (France); Volokitin, A. S. [IZMIRAN, Troitsk, 142190, Moscow (Russian Federation); Krasnoselskikh, V. V., E-mail: catherine.krafft@u-psud.fr [Laboratoire de Physique et Chimie de l’Environnement et de l’Espace, 3A Av. de la Recherche Scientifique, F-45071 Orléans Cedex 2 (France)

    2015-08-20

    Langmuir turbulence excited by electron flows in solar wind plasmas is studied on the basis of numerical simulations. In particular, nonlinear wave decay processes involving ion-sound (IS) waves are considered in order to understand their dependence on external long-wavelength plasma density fluctuations. In the presence of inhomogeneities, it is shown that the decay processes are localized in space and, due to the differences between the group velocities of Langmuir and IS waves, their duration is limited so that a full nonlinear saturation cannot be achieved. The reflection and the scattering of Langmuir wave packets on the ambient and randomly varying density fluctuations lead to crucial effects impacting the development of the IS wave spectrum. Notably, beatings between forward propagating Langmuir waves and reflected ones result in the parametric generation of waves of noticeable amplitudes and in the amplification of IS waves. These processes, repeated at different space locations, form a series of cascades of wave energy transfer, similar to those studied in the frame of weak turbulence theory. The dynamics of such a cascading mechanism and its influence on the acceleration of the most energetic part of the electron beam are studied. Finally, the role of the decay processes in the shaping of the profiles of the Langmuir wave packets is discussed, and the waveforms calculated are compared with those observed recently on board the spacecraft Solar TErrestrial RElations Observatory and WIND.

  7. Geothermal gradient drilling, north-central Cascades of Oregon, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Youngquist, W.

    1980-01-01

    A geothermal gradient drilling program was conducted on the western flank of the north-central Cascade Mountains in Oregon. Six wells were drilled during this program, although in effect seven were drilled, as two wells were drilled at site 3, the second well, however, actually going to a lesser depth than the first. Three of the wells (3, 4, and 5) were drilled in areas which topographically are subject to strong throughflows of ground water. None of these wells reached the regional water table, and all showed essentially isothermal geothermal gradients. The single well which was started essentially at the water table (well 6) shows a linear temperature rise with depth essentially from the top of the well bore. Well No. 2 shows an isothermal gradient down to the level of the regional water table and then shows a linear gradient of about 70/sup 0/C/km from the regional water table to total depth.

  8. Higher-order Kerr effect and harmonic cascading in gases

    DEFF Research Database (Denmark)

    Bache, Morten; Eilenberger, Falk; Minardi, Stefano

    2012-01-01

    The higher-order Kerr effect (HOKE) has recently been advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth-order nonlinearity that is negative and significant. Higher......-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths, cascading increases the HOKE saturation intensity, while for longer wavelengths cascading will decrease the HOKE saturation intensity....

  9. Higher-order Kerr effect and harmonic cascading in gases.

    Science.gov (United States)

    Bache, Morten; Eilenberger, Falk; Minardi, Stefano

    2012-11-15

    The higher-order Kerr effect (HOKE) has recently been advocated to explain measurements of the saturation of the nonlinear refractive index in gases. Here we show that cascaded third-harmonic generation results in an effective fifth-order nonlinearity that is negative and significant. Higher-order harmonic cascading will also occur from the HOKE, and the cascading contributions may significantly modify the observed nonlinear index change. At lower wavelengths, cascading increases the HOKE saturation intensity, while for longer wavelengths cascading will decrease the HOKE saturation intensity.

  10. Wave motion in elastic solids

    CERN Document Server

    Graff, Karl F

    1991-01-01

    This highly useful textbook presents comprehensive intermediate-level coverage of nearly all major topics of elastic wave propagation in solids. The subjects range from the elementary theory of waves and vibrations in strings to the three-dimensional theory of waves in thick plates. The book is designed not only for a wide audience of engineering students, but also as a general reference for workers in vibrations and acoustics. Chapters 1-4 cover wave motion in the simple structural shapes, namely strings, longitudinal rod motion, beams and membranes, plates and (cylindrical) shells. Chapter

  11. INTERFERENCE OF UNIDIRECTIONAL SHOCK WAVES

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2015-05-01

    Full Text Available Subject of study.We consider interference of unidirectional shock waves or, as they are called, catching up shock waves. The scope of work is to give a classification of the shock-wave structures that arise in this type of interaction of shock waves, and the area of their existence. Intersection of unidirectional shock waves results in arising of a shock-wave structure at the intersection point, which contains the main shock wave, tangential discontinuity and one more reflected gas-dynamic discontinuity of unknown beforehand type. The problem of determining the type of reflected discontinuity is the main problem that one has to solve in the study of catching shock waves interference. Main results.The paper presents the pictures of shock-wave structures arising at the interaction of catching up shock waves. The areas with a regular and irregular unidirectional interaction of shocks are described. Characteristic shock-wave structures are of greatest interest, where reflected gas-dynamic discontinuity degenerates into discontinuous characteristics. Such structures have a number of extreme properties. We have found the areas of existence for such shock-wave structures. There are also areas in which the steady-state solution is not available. The latter has determined revival of interest for the theoretical study of the problem, because the facts of sudden shock-wave structure destruction inside the air intake of supersonic aircrafts at high Mach numbers have been discovered. Practical significance.The theory of interference for unidirectional shock waves and design procedure are usable in the design of supersonic air intakes. It is also relevant for application possibility investigation of catching up oblique shock waves to create overcompressed detonation in perspective detonation air-jet and rocket engines.

  12. Reflected-wave maser. [low noise amplifier

    Science.gov (United States)

    Clauss, R. C. (Inventor)

    1976-01-01

    A number of traveling-wave, slow-wave maser structures, containing active maser material but absent the typical ferrite isolators, are immersed in a nonuniform magnetic field. The microwave signal to be amplified is inserted at a circulator which directs the signal to a slow-wave structure. The signal travels through the slow-wave structure, being amplified according to the distance traveled. The end of the slow-wave structure farthest from the circulator is arranged to be a point of maximum reflection of the signal traveling through the slow-wave structure. As a consequence, the signal to be amplified traverses the slow-wave structure again, in the opposite direction (towards the circulator) experiencing amplification equivalent to that achieved by a conventional traveling-wave maser having twice the length. The circulator directs the amplified signal to following like stages of amplification. Isolators are used in between stages to prevent signals from traveling in the wrong direction, between the stages. Reduced signal loss is experienced at each stage. The high gain produced by each slow-wave structure is reduced to a moderate value by use of a nonuniform magnetic field which also broadens the line width of the maser material. The resulting bandwidth can be exceptionally wide. Cascaded stages provide high gain, exceptionally wide bandwith and very low noise temperature.

  13. Gravitation Waves

    CERN Multimedia

    CERN. Geneva

    2005-01-01

    We will present a brief introduction to the physics of gravitational waves and their properties. We will review potential astrophysical sources of gravitational waves, and the physics and astrophysics that can be learned from their study. We will survey the techniques and technologies for detecting gravitational waves for the first time, including bar detectors and broadband interferometers, and give a brief status report on the international search effort, with special emphasis on the LIGO detectors and search results.

  14. Optical vortex interaction and generation via nonlinear wave mixing

    Energy Technology Data Exchange (ETDEWEB)

    Lenzini, F. [INLN, Universite de Nice-Sophia Antipolis, CNRS, 1361 route des Lucioles, FR-06560 Valbonne (France); Dipartimento di Fisica, Universita di Firenze, via Sansone 1, IT-50019 Sesto Fiorentino (Italy); Residori, S.; Bortolozzo, U. [INLN, Universite de Nice-Sophia Antipolis, CNRS, 1361 route des Lucioles, FR-06560 Valbonne (France); Arecchi, F. T. [Dipartimento di Fisica, Universita di Firenze, via Sansone 1, IT-50019 Sesto Fiorentino (Italy)

    2011-12-15

    Optical vortex beams are made to interact via degenerate two-wave mixing in a Kerr-like nonlinear medium. Vortex mixing is shown to occur inside the medium, leading to exchange of topological charge and cascaded generation of vortex beams. A mean-field model is developed and is shown to account for the selection rules of the topological charges observed after the wave-mixing process. Fractional charges are demonstrated to follow the same rules as for integer charges.

  15. Vlasov simulations of kinetic Alfvén waves at proton kinetic scales

    Energy Technology Data Exchange (ETDEWEB)

    Vásconez, C. L. [Dipartimento di Fisica, Università della Calabria, I-87036 Cosenza (Italy); Observatorio Astronómico de Quito, Escuela Politécnica Nacional, Quito (Ecuador); Valentini, F.; Veltri, P. [Dipartimento di Fisica, Università della Calabria, I-87036 Cosenza (Italy); Camporeale, E. [Centrum Wiskunde and Informatica, Amsterdam (Netherlands)

    2014-11-15

    Kinetic Alfvén waves represent an important subject in space plasma physics, since they are thought to play a crucial role in the development of the turbulent energy cascade in the solar wind plasma at short wavelengths (of the order of the proton gyro radius ρ{sub p} and/or inertial length d{sub p} and beyond). A full understanding of the physical mechanisms which govern the kinetic plasma dynamics at these scales can provide important clues on the problem of the turbulent dissipation and heating in collisionless systems. In this paper, hybrid Vlasov-Maxwell simulations are employed to analyze in detail the features of the kinetic Alfvén waves at proton kinetic scales, in typical conditions of the solar wind environment (proton plasma beta β{sub p} = 1). In particular, linear and nonlinear regimes of propagation of these fluctuations have been investigated in a single-wave situation, focusing on the physical processes of collisionless Landau damping and wave-particle resonant interaction. Interestingly, since for wavelengths close to d{sub p} and β{sub p} ≃ 1 (for which ρ{sub p} ≃ d{sub p}) the kinetic Alfvén waves have small phase speed compared to the proton thermal velocity, wave-particle interaction processes produce significant deformations in the core of the particle velocity distribution, appearing as phase space vortices and resulting in flat-top velocity profiles. Moreover, as the Eulerian hybrid Vlasov-Maxwell algorithm allows for a clean almost noise-free description of the velocity space, three-dimensional plots of the proton velocity distribution help to emphasize how the plasma departs from the Maxwellian configuration of thermodynamic equilibrium due to nonlinear kinetic effects.

  16. Cascade morphology transition in bcc metals

    Energy Technology Data Exchange (ETDEWEB)

    Setyawan, Wahyu; Selby, A.; Juslin, Niklas; Stoller, Roger E.; Wirth, Brian D.; Kurtz, Richard J.

    2015-06-10

    Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent, $b$, in the defect production curve as a function of cascade energy ($N_F$$ \\sim$$E_{MD}^b$). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, $\\mu$, between the high- and the low-energy regime. Using Cr, Fe, Mo and W data, an empirical formula of $\\mu$ as a function of displacement threshold energy, $E_d$, is presented for bcc metals.

  17. Cascade Apartments: Deep Energy Multifamily Retrofit

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Mattheis, L. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kunkle, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Howard, L. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lubliner, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2014-02-01

    In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington (marine climate.)This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary BA research questions : 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio (SIR) of the retrofit package after considering utility window incentives and KCHA capitol improvement funding.

  18. Cascade Apartments: Deep Energy Multifamily Retrofit

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, A. [Washington State Univ. Energy Program, Olympia, WA (United States); Mattheis, L. [Washington State Univ. Energy Program, Olympia, WA (United States); Kunkle, R. [Washington State Univ. Energy Program, Olympia, WA (United States); Howard, L. [Washington State Univ. Energy Program, Olympia, WA (United States); Lubliner, M. [Washington State Univ. Energy Program, Olympia, WA (United States)

    2014-02-01

    In December of 2009-10, King County Housing Authority (KCHA) implemented energy retrofit improvements in the Cascade multifamily community, located in Kent, Washington (marine climate.)This research effort involved significant coordination from stakeholders KCHA, WA State Department of Commerce, utility Puget Sound Energy, and Cascade tenants. This report focuses on the following three primary BA research questions: 1. What are the modeled energy savings using DOE low income weatherization approved TREAT software? 2. How did the modeled energy savings compare with measured energy savings from aggregate utility billing analysis? 3. What is the Savings to Investment Ratio (SIR) of the retrofit package after considering utility window incentives and KCHA capitol improvement funding.

  19. Regimes of turbulence without an energy cascade

    CERN Document Server

    Barenghi, C F; Baggaley, A W

    2016-01-01

    Experiments and numerical simulations of turbulent $^4$He and $^3$He-B have established that, at hydrodynamic length scales larger than the average distance between quantum vortices, the energy spectrum obeys the same 5/3 Kolmogorov law which is observed in the homogeneous isotropic turbulence of ordinary fluids. The importance of the 5/3 law is that it points to the existence of a Richardson energy cascade from large eddies to small eddies. However, there is also evidence of quantum turbulent regimes without Kolmogorov scaling. This raises the important questions of why, in such regimes, the Kolmogorov spectrum fails to form, what is the physical nature of turbulence without energy cascade, and whether hydrodynamical models can account for the unusual behaviour of turbulent superfluid helium. In this work we describe simple physical mechanisms which prevent the formation of Kolmogorov scaling in the thermal counterflow, and analyze the conditions necessary for emergence of quasiclassical regime in quantum tu...

  20. Cascaded Multicell Trans-Z-Source Inverters

    DEFF Research Database (Denmark)

    Li, Ding; Chiang Loh, Poh; Zhu, Miao

    2013-01-01

    strictly be small to prevent overvoltages caused by switching of their winding currents. To avoid these related problems, cascaded trans-Z-source inverters are proposed. They use multiple magnetic cells in an alternately cascading pattern rather than a single magnetic cell with large turns ratio....... Simulation and experimental results have shown that the multicell inverters can produce the same high-voltage gain, while keeping currents and voltages of the components low. The inverters can also step down their output voltages like a traditional voltage-source inverter without compromising waveform......Inverters with high-output voltage gain usually face the problem of high-input current flowing through their components. The problem might further be exaggerated if the inverters use high-frequency magnetic devices like transformers or coupled inductors. Leakage inductances of these devices must...

  1. Cascaded trans-z-source inverters

    DEFF Research Database (Denmark)

    Li, Ding; Loh, Poh Chiang; Zhu, Miao

    2011-01-01

    Z-source inverter is a recently proposed single-stage inverter with added voltage-boost capability for complementing the usual voltage-buck operation of a traditional voltage-source inverter. As long as the transformer element added in to the z-source concept, a trans-z-source inverter with one...... transformer and one capacitor is reported recently. This paper has adapted the cascaded concept into the trans-z-source and trans-quasi-z-source inverters to extend each to the cascaded topologies before combination is made with allowing more sources embedded which reduces the capacitor voltage and enhanced...... the compatibility for distributed sources. Unlike existing techniques, voltage stresses within the proposed inverters are better distributed among the passive components. Theoretical analysis for explaining these operating features has already been discussed before simulation were performed and an experimental...

  2. Janus Waves

    OpenAIRE

    Papazoglou, Dimitris G.; Fedorov, Vladimir Yu.; Tzortzakis, Stelios

    2016-01-01

    We show the existence of a family of waves that share a common interesting property affecting the way they propagate and focus. These waves are a superposition of twin waves, which are conjugate to each other under inversion of the propagation direction. In analogy to holography, these twin "real" and "virtual" waves are related respectively to the converging and the diverging part of the beam and can be clearly visualized in real space at two distinct foci under the action of a focusing lens...

  3. Supersonic Chordwise Bending Flutter in Cascades

    Science.gov (United States)

    1975-05-31

    bonding agent was injected via hypodermic needles after the blade tabs were properly inserted, The integrity and repeatability of the mounting of the indi...in conjunction with NASTRAN predictions and supersonic cascade aerodynamic computa- tions. Comparisons between theory and experiment are discussed. DD...explored by using the theory of .ieferences 3 and 4 to calculate the aero- dynamic damping for a typical chordwise blade deformation (Reference 6 and

  4. How do cilia organize signalling cascades?

    Science.gov (United States)

    Nachury, Maxence V

    2014-09-05

    Cilia and flagella are closely related centriole-nucleated protrusions of the cell with roles in motility and signal transduction. Two of the best-studied signalling pathways organized by cilia are the transduction cascade for the morphogen Hedgehog in vertebrates and the mating pathway that initiates gamete fusion in the unicellular green alga Chlamydomonas reinhardtii. What is the role of cilia in these signalling transduction cascades? In both Hedgehog and mating pathways, all signalling intermediates have been found to localize to cilia, and, for some signalling factors, ciliary localization is regulated by pathway activation. Given a concentration factor of three orders of magnitude provided by translocating a protein into the cilium, the compartment model proposes that cilia act as miniaturized reaction tubes bringing signalling factors and processing enzymes in close proximity. On the other hand, the scaffolding model views the intraflagellar transport machinery, whose primary function is to build cilia and flagella, as a molecular scaffold for the mating transduction cascade at the flagellar membrane. While these models may coexist, it is hoped that a precise understanding of the mechanisms that govern signalling inside cilia will provide a satisfying answer to the question 'how do cilia organize signalling?'. This review covers the evidence supporting each model of signalling and outlines future directions that may address which model applies in given biological settings. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  5. Cascade laser applications: trends and challenges

    Science.gov (United States)

    d'Humières, B.; Margoto, Éric; Fazilleau, Yves

    2016-03-01

    When analyses need rapid measurements, cost effective monitoring and miniaturization, tunable semiconductor lasers can be very good sources. Indeed, applications like on-field environmental gas analysis or in-line industrial process control are becoming available thanks to the advantage of tunable semiconductor lasers. Advances in cascade lasers (CL) are revolutionizing Mid-IR spectroscopy with two alternatives: interband cascade lasers (ICL) in the 3-6μm spectrum and quantum cascade lasers (QCL), with more power from 3 to 300μm. The market is getting mature with strong players for driving applications like industry, environment, life science or transports. CL are not the only Mid-IR laser source. In fact, a strong competition is now taking place with other technologies like: OPO, VCSEL, Solid State lasers, Gas, SC Infrared or fiber lasers. In other words, CL have to conquer a share of the Mid-IR application market. Our study is a market analysis of CL technologies and their applications. It shows that improvements of components performance, along with the progress of infrared laser spectroscopy will drive the CL market growth. We compare CL technologies with other Mid-IR sources and estimate their share in each application market.

  6. Metamaterials and wave control

    CERN Document Server

    Lheurette, Eric

    2013-01-01

    Since the concept was first proposed at the end of the 20th Century, metamaterials have been the subject of much research and discussion throughout the wave community. More than 10 years later, the number of related published articles is increasing significantly. Onthe one hand, this success can be attributed to dreams of new physical objects which are the consequences of the singular properties of metamaterials. Among them, we can consider the examples of perfect lensing and invisibility cloaking. On other hand,metamaterials also provide new tools for the design of well-known wave functions s

  7. High sensitivity detection of NO2 employing cavity ringdown spectroscopy and an external cavity continuously tunable quantum cascade laser.

    Science.gov (United States)

    Rao, Gottipaty N; Karpf, Andreas

    2010-09-10

    A trace gas sensor for the detection of nitrogen dioxide based on cavity ringdown spectroscopy (CRDS) and a continuous wave external cavity tunable quantum cascade laser operating at room temperature has been designed, and its features and performance characteristics are reported. By measuring the ringdown times of the cavity at different concentrations of NO(2), we report a sensitivity of 1.2 ppb for the detection of NO(2) in Zero Air.

  8. Improvements of sensorimotor processes during action cascading associated with changes in sensory processing architecture-insights from sensory deprivation.

    Science.gov (United States)

    Gohil, Krutika; Hahne, Anja; Beste, Christian

    2016-06-20

    In most everyday situations sensorimotor processes are quite complex because situations often require to carry out several actions in a specific temporal order; i.e. one has to cascade different actions. While it is known that changes to stimuli affect action cascading mechanisms, it is unknown whether action cascading changes when sensory stimuli are not manipulated, but the neural architecture to process these stimuli is altered. In the current study we test this hypothesis using prelingually deaf subjects as a model to answer this question. We use a system neurophysiological approach using event-related potentials (ERPs) and source localization techniques. We show that prelingually deaf subjects show improvements in action cascading. However, this improvement is most likely not due to changes at the perceptual (P1-ERP) and attentional processing level (N1-ERP), but due to changes at the response selection level (P3-ERP). It seems that the temporo-parietal junction (TPJ) is important for these effects to occur, because the TPJ comprises overlapping networks important for the processing of sensory information and the selection of responses. Sensory deprivation thus affects cognitive processes downstream of sensory processing and only these seem to be important for behavioral improvements in situations requiring complex sensorimotor processes and action cascading.

  9. Rossby Waves

    OpenAIRE

    2005-01-01

    tut quiz Tutorial Quiz Interactive Media Element This interactive tutorial reviews the mechanisms of Rossby waves. Rossby waves in both the northern and southern hemispheres are considered. The interactions involve answering simple fill-in-the-blank questions. Diagrams are used to illustrate some of the concepts reviewed. MR4322 Dynamic Meteorology

  10. Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter; Friis-Madsen, Erik

    2008-01-01

    Since March 2003 a prototype of Wave Dragon has been tested in an inland sea in Denmark. This has been a great success with all subsystems tested and improved through working in an offshore environment. The project has proved the Wave Dragon device and has enabled the next stage, a production sized...

  11. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star.......Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star....

  12. Picosecond-pulse generation over 10 GHz repetition rate based on cascaded semiconductor optical amplifiers

    Science.gov (United States)

    Tai, Wenlong; Yang, Tianxin; Ge, Chunfeng; Jia, Dongfang

    2017-02-01

    A cavity-free setup to generate short pulses at high repetition rate is introduced, which is based on four-wave mixing (FWM) in cascaded semiconductor optical amplifiers (SOAs). High repetition rate picosecond-pulse is important in optical communication and all-optic information processing systems. Cavity-free setup based on SOA means without ring cavity, which is stable and easy to be large-scale integrated. In this paper, we obtain picosecond-pulse around 10GHz repetition rate and the side-mode suppression ratio is 23 dB. Moreover, the repetition rate and center wavelength of optical pulse is tunable.

  13. Superradiant emission from a cascade atomic ensemble by positive-P phase space method simulation

    Science.gov (United States)

    Jen, Hsiang-Hua

    2012-06-01

    We numerically simulate the superradiant emission properties from an atomic ensemble with cascade level configuration. The correlated spontaneous emissions (signal then idler fields) are initiated by quantum fluctuations of the ensemble. We apply the positive-P phase space method to investigate the dynamics of the atoms and counter-propagating emissions in the four-wave mixing condition. The light field intensities are calculated, and the signal-idler correlation function is studied for different optical depths of the atomic ensemble. Shorter correlation time scale for a denser atomic ensemble implies a broader spectral window required to store or retrieve the idler pulse.

  14. Cascaded Brillouin lasing in monolithic barium fluoride whispering gallery mode resonators

    CERN Document Server

    Lin, Guoping; Saleh, Khaldoun; Martinenghi, Romain; Beugnot, Jean-Charles; Sylvestre, Thibaut; Chembo, Yanne K

    2015-01-01

    We report the observation of stimulated Brillouin scattering and lasing at 1550~nm in barium fluoride (BaF$_2$) crystal. Brillouin lasing was achieved with ultra-high quality ($Q$) factor monolithic whispering gallery mode (WGM) mm-size disk resonators. Overmoded resonators were specifically used to provide cavity resonances for both the pump and all Brillouin Stokes waves. Single and multiple Brillouin Stokes radiations with frequency shift ranging from $8.2$ GHz up to $49$ GHz have been generated through cascaded Brillouin lasing. BaF$_2$ resonator-based Brillouin lasing can find potential applications for high-coherence lasers and microwave photonics.

  15. Wave Solutions

    CERN Document Server

    Christov, Ivan C

    2012-01-01

    In classical continuum physics, a wave is a mechanical disturbance. Whether the disturbance is stationary or traveling and whether it is caused by the motion of atoms and molecules or the vibration of a lattice structure, a wave can be understood as a specific type of solution of an appropriate mathematical equation modeling the underlying physics. Typical models consist of partial differential equations that exhibit certain general properties, e.g., hyperbolicity. This, in turn, leads to the possibility of wave solutions. Various analytical techniques (integral transforms, complex variables, reduction to ordinary differential equations, etc.) are available to find wave solutions of linear partial differential equations. Furthermore, linear hyperbolic equations with higher-order derivatives provide the mathematical underpinning of the phenomenon of dispersion, i.e., the dependence of a wave's phase speed on its wavenumber. For systems of nonlinear first-order hyperbolic equations, there also exists a general ...

  16. Water Waves The Mathematical Theory with Applications

    CERN Document Server

    Stoker, J J

    2011-01-01

    Offers an integrated account of the mathematical hypothesis of wave motion in liquids with a free surface, subjected to gravitational and other forces. Uses both potential and linear wave equation theories, together with applications such as the Laplace and Fourier transform methods, conformal mapping and complex variable techniques in general or integral equations, methods employing a Green's function. Coverage includes fundamental hydrodynamics, waves on sloping beaches, problems involving waves in shallow water, the motion of ships and much more.

  17. Low Power Consumption Substrate-Emitting DFB Quantum Cascade Lasers

    Science.gov (United States)

    Liu, Chuan-Wei; Zhang, Jin-Chuan; Jia, Zhi-Wei; Zhuo, Ning; Zhai, Shen-Qiang; Wang, Li-Jun; Liu, Jun-Qi; Liu, Shu-Man; Liu, Feng-Qi; Wang, Zhan-Guo

    2017-09-01

    In the present work, an ultra-low power consumption substrate-emitting distributed feedback (DFB) quantum cascade laser (QCL) was developed. The continuous-wave (CW) threshold power dissipation is reduced to 0.43 W at 25 °C by shortening the cavity length to 0.5 mm and depositing high-reflectivity (HR) coating on both facets. As far as we know, this is the recorded threshold power dissipation of QCLs in the same conditions. Single-mode emission was achieved by employing a buried second-order grating. Mode-hop free emission can be observed within a wide temperature range from 15 to 105 °C in CW mode. The divergence angles are 22.5o and 1.94o in the ridge-width direction and cavity-length direction, respectively. The maximum optical power in CW operation was 2.4 mW at 25 °C, which is sufficient to spectroscopy applications.

  18. The Seismic Structure of the Mantle Wedge under Cascade Volcanoes

    Science.gov (United States)

    Levander, A.; Liu, K.; Porritt, R. W.; Allen, R. M.

    2011-12-01

    Under a number of Cascade volcanoes we have identified a characteristic seismic signature in individual station Ps receiver functions and in Ps CCP image volumes made from USArray Transportable Array and Flexible Array stations. In the mantle wedge, the CCP images and the RFs show a strong negative event just below the Moho, paired with a weak to moderate positive event between 50-70 km, and a strong slab event. At most of these volcanoes, a strong negative signal also appears between 15 and 25 km depth in the crust. The signature is particularly clear under Mt. Lassen and Mt. Shasta in data from FAME (Flexible Array Mendocino Experiment), where instruments were close to the volcanic centers. Comparing the average Cascadia volcano signature to those of stations throughout the western U.S. and specifically those of the Cascadia backarc region, shows that this signal is unique to the Cascadia volcanoes. Joint inversion of the Ps receiver functions and ambient noise Rayleigh wave phase velocities (Porritt et al., 2011; Liu et al., submitted) for those volcanoes with the paired events provides 1D shear velocity profiles having common characteristics. A strong sub-Moho low velocity zone from 5 to 15 km thick gives rise to the paired negative-positive signals in the receiver functions. The sub-Moho low velocity zones, with velocities of 3.7 CIDER 2011 summer program.

  19. Artificial earthquake record generation using cascade neural network

    Directory of Open Access Journals (Sweden)

    Bani-Hani Khaldoon A.

    2017-01-01

    Full Text Available This paper presents the results of using artificial neural networks (ANN in an inverse mapping problem for earthquake accelerograms generation. This study comprises of two parts: 1-D site response analysis; performed for Dubai Emirate at UAE, where eight earthquakes records are selected and spectral matching are performed to match Dubai response spectrum using SeismoMatch software. Site classification of Dubai soil is being considered for two classes C and D based on shear wave velocity of soil profiles. Amplifications factors are estimated to quantify Dubai soil effect. Dubai’s design response spectra are developed for site classes C & D according to International Buildings Code (IBC -2012. In the second part, ANN is employed to solve inverse mapping problem to generate time history earthquake record. Thirty earthquakes records and their design response spectrum with 5% damping are used to train two cascade forward backward neural networks (ANN1, ANN2. ANN1 is trained to map the design response spectrum to time history and ANN2 is trained to map time history records to the design response spectrum. Generalized time history earthquake records are generated using ANN1 for Dubai’s site classes C and D, and ANN2 is used to evaluate the performance of ANN1.

  20. Quantum cascade laser-based photoacoustic sulfuryl fluoride sensing

    Science.gov (United States)

    Minini, Kariza Mayra Silva; Bueno, Sâmylla Cristina Espécie; da Silva, Marcelo Gomes; Sthel, Marcelo Silva; Vargas, Helion; Angster, Judit; Miklós, András

    2017-02-01

    Although sulfuryl fluoride (SO2F2) is an efficient fumigant that does not react with the surface of indoor materials and does not reduce the stratospheric ozone shield, there are some concerns about its use. It is a toxic gas that attacks the central nervous system, and its global warming potential (GWP) value is 4780 for 100 years' time. Therefore, it is a clear necessity of implementing detection methods for tracing such a molecule. In this work a sensitive photoacoustic setup was built to detect SO2F2 at concentrations of parts per billion by volume (ppbv). The symmetric S-O stretching mode was excited by a continuous-wave quantum cascade laser with radiation wavenumber ranging from 1275.7 to 1269.3 cm-1. The photoacoustic signal was generated by modulating the laser wavenumber at the first longitudinal mode of the photoacoustic cell with amplitude depth of 5 × 10-3 cm-1. The detection of a minimum SO2F2 concentration of 20 ppbv was achieved.

  1. Cascade pathway of filopodia formation downstream of SCAR.

    Science.gov (United States)

    Biyasheva, Assel; Svitkina, Tatyana; Kunda, Patricia; Baum, Buzz; Borisy, Gary

    2004-02-29

    The protrusion of two distinct actin-containing organelles, lamellipodia and filopodia, is thought to be regulated by two parallel pathways: from Rac1 through Scar/WAVEs to lamellipodia, and from Cdc42 through N-WASP to filopodia. We tested this hypothesis in Drosophila, which contains a single gene for each WASP subfamilies, SCAR and WASp. We performed targeted depletion of SCAR or WASp by dsRNA-mediated interference in two Drosophila cultured cell lines expressing lamellipodial and filopodial protrusion. Knockdown was verified by laser capture microdissection and RT-PCR, as well as western blotting. Morphometrical, kinetic and electron microscopy analyses of the SCAR-depleted phenotype in both cell types revealed strong inhibition of lamellipodial formation and cell spreading, as expected. More importantly, filopodia formation was also strongly inhibited, which is not consistent with the parallel pathway hypothesis. By contrast, depletion of WASp did not produce any significant phenotype, except for a slight inhibition of spreading, showing that both lamellipodia and filopodia in Drosophila cells are regulated predominantly by SCAR. We propose a new, cascade pathway model of filopodia regulation in which SCAR signals to lamellipodia and then filopodia arise from lamellipodia in response to additional signal(s).

  2. Lipid-cytokine-chemokine cascades orchestrate leukocyte recruitment in inflammation.

    Science.gov (United States)

    Sadik, Christian D; Luster, Andrew D

    2012-02-01

    Chemoattractants are pivotal mediators of host defense, orchestrating the recruitment of immune cells into sites of infection and inflammation. Chemoattractants display vast chemical diversity and include bioactive lipids, proteolytic fragments of serum proteins, and chemokines (chemotactic cytokines). All chemoattractants induce chemotaxis by activating seven-transmembrane-spanning GPCRs expressed on immune cells, establishing the concept that all chemoattractants are related in function. However, although chemoattractants have overlapping functions in vitro, recent in vivo data have revealed that they function, in many cases, nonredundantly in vivo. The chemically diverse nature of chemoattractants contributes to the fine control of leukocyte trafficking in vivo, with sequential chemoattractant use guiding immune cell recruitment into inflammatory sites. Lipid mediators frequently function as initiators of leukocyte recruitment, attracting the first immune cells into tissues. These initial responding immune cells produce cytokines locally, which in turn, induce the local release of chemokines. Local chemokine production then markedly amplifies subsequent waves of leukocyte recruitment. These new discoveries establish a paradigm for leukocyte recruitment in inflammation--described as lipid-cytokine-chemokine cascades--as a driving force in the effector phase of immune responses.

  3. Vertebrate predators have minimal cascading effects on plant production or seed predation in an intact grassland ecosystem

    Science.gov (United States)

    John L. Maron; Dean E. Pearson

    2011-01-01

    The strength of trophic cascades in terrestrial habitats has been the subject of considerable interest and debate. We conducted an 8-year experiment to determine how exclusion of vertebrate predators, ungulates alone (to control for ungulate exclusion from predator exclusion plots) or none of these animals influenced how strongly a three-species assemblage of rodent...

  4. Wave loads on foundations for wind turbines. A literature survey; Vaaglaster paa fundament till vindkraftverk - systemdynamik och utmattning: Litteraturstudie

    Energy Technology Data Exchange (ETDEWEB)

    Carlen, Ingemar

    2001-05-01

    This report is an overview of literature covering the influence of wave loads on foundations for wind power plants. Relevant subjects are wave motion, wave forces on slender structures, wave statistics for the Swedish coast together with planning and certification.

  5. Nonlinear Water Waves

    CERN Document Server

    2016-01-01

    This volume brings together four lecture courses on modern aspects of water waves. The intention, through the lectures, is to present quite a range of mathematical ideas, primarily to show what is possible and what, currently, is of particular interest. Water waves of large amplitude can only be fully understood in terms of nonlinear effects, linear theory being not adequate for their description. Taking advantage of insights from physical observation, experimental evidence and numerical simulations, classical and modern mathematical approaches can be used to gain insight into their dynamics. The book presents several avenues and offers a wide range of material of current interest. Due to the interdisciplinary nature of the subject, the book should be of interest to mathematicians (pure and applied), physicists and engineers. The lectures provide a useful source for those who want to begin to investigate how mathematics can be used to improve our understanding of water wave phenomena. In addition, some of the...

  6. Design of Triple-Band Bandpass Filter Using Cascade Tri-Section Stepped Impedance Resonators

    Directory of Open Access Journals (Sweden)

    Gunawan Wibisono

    2016-06-01

    Full Text Available In this research, a triple-band bandpass filter (BPF using a cascade tri section step impedance resonator (TSSIR, which can be operated at 900 MHz, 1,800 MHz, and 2,600 MHz simultaneously, was designed, fabricated and evaluated. Advanced Design System (ADS was used to design and simulate the proposed BPF. The proposed BPF using cascade TSSIR was fabricated on an FR4 substrate with dielectric permittivity, substrate thickness and loss tangent at 4.3, 1.6 mm and 0.0017, respectively. The performance parameters of the proposed BPF were characterized by insertion loss, return loss, voltage standing wave ratio (VSWR and group delay. The performance results from the simulation were compared to those of the fabricated BPF. The results showed that the performances from both the simulated and the fabricated BPF satisfied the design specifications and were in close agreement with each other. Furthermore, the results indicated that the proposed BPF using cascade TSSIR performed better than a hairpin BPF with TSSIR.

  7. Design and Fabrication of Tri-Stopband Bandstop Filters Using Cascaded and Multi-Armed Methods

    Directory of Open Access Journals (Sweden)

    A. Boutejdar

    2017-10-01

    Full Text Available In this paper, we proposed a compact C-open-loop ring resonator and its equivalent circuit. The second cascaded BSF are designed using this simple C-ring resonator. The double ring BPF consists of two cascaded C-ring resonators, which are placed on the RO4003 substrate, while the other triple BSF structure consists of tree cascaded C-ring resonators, which are connected with input and output through microstrip feed lines. The both filters are simulated, optimized and partially realized using MWR simulator and Anritsu E5072A vector network analyzer VNA. In order to reduce the size and to improve the filter characteristics, novel compact filter topologies are designed basing on the previous structures. The proposed multi-band bandstop filters consist of several open-loop ring resonators placed vertically overlapping (coupled multi-armed ring resonator. Using this idea, the filter topologies with design flexibility, close size and excellent results are reached. The novel compact multi-band bandstop filters produce several stopband along a frequency range from DC to 9 GHz, in which each separate band exhibits an acceptable and useful bandwidth. Each stopband has regenerated two reflexion zeros, what leads to a good sharpness factors in the transition domains. Good agreement between the experimental results, full-wave simulation has been achieved. This new filter idea can be very attractive for the nowadays multilayer and compact radio frequency integrated circuit design.

  8. Cascade Type-I Quantum Well GaSb-Based Diode Lasers

    Directory of Open Access Journals (Sweden)

    Leon Shterengas

    2016-05-01

    Full Text Available Cascade pumping of type-I quantum well gain sections was utilized to increase output power and efficiency of GaSb-based diode lasers operating in a spectral region from 1.9 to 3.3 μm. Carrier recycling between quantum well gain stages was realized using band-to-band tunneling in GaSb/AlSb/InAs heterostructure complemented with optimized electron and hole injector regions. Coated devices with an ~100-μm-wide aperture and a 3-mm-long cavity demonstrated continuous wave (CW output power of 1.96 W near 2 μm, 980 mW near 3 μm, 500 mW near 3.18 μm, and 360 mW near 3.25 μm at 17–20 °C—a nearly or more than twofold increase compared to previous state-of-the-art diode lasers. The utilization of the different quantum wells in the cascade laser heterostructure was demonstrated to yield wide gain lasers, as often desired for tunable laser spectroscopy. Double-step etching was utilized to minimize both the internal optical loss and the lateral current spreading penalties in narrow-ridge lasers. Narrow-ridge cascade diode lasers operate in a CW regime with ~100 mW of output power near and above 3 μm and above 150 mW near 2 μm.

  9. Heat cascading regenerative sorption heat pump

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1995-01-01

    A simple heat cascading regenerative sorption heat pump process with rejected or waste heat from a higher temperature chemisorption circuit (HTCC) powering a lower temperature physisorption circuit (LTPC) which provides a 30% total improvement over simple regenerative physisorption compression heat pumps when ammonia is both the chemisorbate and physisorbate, and a total improvement of 50% or more for LTPC having two pressure stages. The HTCC contains ammonia and a chemisorbent therefor contained in a plurality of canisters, a condenser-evaporator-radiator system, and a heater, operatively connected together. The LTPC contains ammonia and a physisorbent therefor contained in a plurality of compressors, a condenser-evaporator-radiator system, operatively connected together. A closed heat transfer circuit (CHTC) is provided which contains a flowing heat transfer liquid (FHTL) in thermal communication with each canister and each compressor for cascading heat from the HTCC to the LTPC. Heat is regenerated within the LTPC by transferring heat from one compressor to another. In one embodiment the regeneration is performed by another CHTC containing another FHTL in thermal communication with each compressor. In another embodiment the HTCC powers a lower temperature ammonia water absorption circuit (LTAWAC) which contains a generator-absorber system containing the absorbent, and a condenser-evaporator-radiator system, operatively connected together. The absorbent is water or an absorbent aqueous solution. A CHTC is provided which contains a FHTL in thermal communication with the generator for cascading heat from the HTCC to the LTAWAC. Heat is regenerated within the LTAWAC by transferring heat from the generator to the absorber. The chemical composition of the chemisorbent is different than the chemical composition of the physisorbent, and the absorbent. The chemical composition of the FHTL is different than the chemisorbent, the physisorbent, the absorbent, and ammonia.

  10. The identification of a cascade hypernucleus

    CERN Document Server

    Mondal, A S; Husain, A; Kasim, M M

    1979-01-01

    In a systematic search for rare hypernuclear species in nuclear emulsion exposed to 3.0 GeV/c K/sup -/-mesons at the CERN PS, an event with three connecting stars has been observed. The two secondary stars are most probably due to the decay of a cascade hypernucleus according to the following channel: /sub Xi //sup -13/-C to /sub Lambda //sup 8 /Be+/sub Lambda //sup 5/He+Q. The binding energy of the Xi - hypernucleus is B/sub Xi /-(/sub Xi //sup 13/-C)=(18.1+or-3.2) MeV. (11 refs).

  11. Chronic traumatic encephalopathy and the availability cascade.

    Science.gov (United States)

    Solomon, Gary S; Sills, Allen

    2014-09-01

    Chronic traumatic encephalopathy (CTE) in sports has been known for > 85 years, and has experienced a resurgence of interest over the past decade, both in the media and in the scientific community. However, there appears to be a disconnection between the public's perception of CTE and the currently available scientific data. The cognitive bias known as the "availability cascade" has been suggested as a reason to explain this rift in knowledge. This review summarizes and updates the history of CTE in sports, discusses recent epidemiological and autopsy studies, summarizes the evidence base related to CTE in sports, and offers recommendations for future directions.

  12. Tracking Control for Switched Cascade Nonlinear Systems

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Dong

    2015-01-01

    Full Text Available The issue of H∞ output tracking for switched cascade nonlinear systems is discussed in this paper, where not all the linear parts of subsystems are stabilizable. The conditions of the solvability for the issue are given by virtue of the structural characteristics of the systems and the average dwell time method, in which the total activation time for stabilizable subsystems is longer than that for the unstabilizable subsystems. At last, a simulation example is used to demonstrate the validity and advantages of the proposed approach.

  13. Cascaded recompression closed brayton cycle system

    Energy Technology Data Exchange (ETDEWEB)

    Pasch, James J.

    2018-01-02

    The present disclosure is directed to a cascaded recompression closed Brayton cycle (CRCBC) system and method of operation thereof, where the CRCBC system includes a compressor for compressing the system fluid, a separator for generating fluid feed streams for each of the system's turbines, and separate segments of a heater that heat the fluid feed streams to different feed temperatures for the system's turbines. Fluid exiting each turbine is used to preheat the fluid to the turbine. In an embodiment, the amount of heat extracted is determined by operational costs.

  14. Long-Haul TCP vs. Cascaded TCP

    OpenAIRE

    Feng, Wu-chun

    2006-01-01

    In this work, we investigate the bandwidth and transfer time of long-haul TCP versus cascaded TCP [5]. First, we discuss the models for TCP throughput. For TCP flows in support of bulk data transfer (i.e., long-lived TCP flows), the TCP throughput models have been derived [2, 3]. These models rely on the congestion-avoidance algorithm of TCP. Though these models cannot be applied with short-lived TCP connections, our interest relative to logistical networking is in longer-li...

  15. Plant MAPK cascades: Just rapid signaling modules?

    KAUST Repository

    Boudsocq, Marie

    2015-08-27

    © 2015 Taylor & Francis Group, LLC. Abscisic acid (ABA) is a major phytohormone mediating important stress-related processes. We recently unveiled an ABA-activated MAPK signaling module constituted of MAP3K17/18-MKK3-MPK1/2/7/14. Unlike classical rapid MAPK activation, we showed that the activation of the new MAPK module is delayed and relies on the MAP3K protein synthesis. In this addendum, we discuss the role of this original and unexpected activation mechanism of MAPK cascades which suggests that MAPKs can regulate both early and longterm plant stress responses.

  16. The impact of a network split on cascading failure processes

    OpenAIRE

    Sloothaak, Fiona; Borst, Sem C.; Zwart, Bert

    2017-01-01

    Cascading failure models are typically used to capture the phenomenon where failures possibly trigger further failures in succession, causing knock-on effects. In many networks this ultimately leads to a disintegrated network where the failure propagation continues independently across the various components. In order to gain insight in the impact of network splitting on cascading failure processes, we extend a well-established cascading failure model for which the number of failures obeys a ...

  17. Large phase shift via polarization-coupling cascading.

    Science.gov (United States)

    Huo, Juan; Chen, Xianfeng

    2012-06-04

    Herein, we propose a phenomenon of "polarization-coupling (PC) cascading" generated in MgO doped periodically poled lithium niobate crystal (PPMgLN). PC cascading contributes to the effective electro-optical (EO) Kerr effect that is several orders of magnitude stronger than the classical ones. Experiment of Newton's rings demonstrates the large phase accumulation during the PC cascaded processes, and the experimental data is identical with the theoretical simulation.

  18. Estimating Failure Propagation in Models of Cascading Blackouts

    Energy Technology Data Exchange (ETDEWEB)

    Dobson, Ian [University of Wisconsin, Madison; Carreras, Benjamin A [ORNL; Lynch, Vickie E [ORNL; Nkei, Bertrand [ORNL; Newman, David E [University of Alaska

    2005-09-01

    We compare and test statistical estimates of failure propagation in data from versions of a probabilistic model of loading-dependent cascading failure and a power systems blackout model of cascading transmission line overloads. The comparisons suggest mechanisms affecting failure propagation and are an initial step towards monitoring failure propagation from practical system data. Approximations to the probabilistic model describe the forms of probability distributions of cascade sizes.

  19. On the relevance of the NPY2-receptor variation for modes of action cascading processes.

    Science.gov (United States)

    Beste, Christian; Stock, Ann-Kathrin; Epplen, Jörg T; Arning, Larissa

    2014-11-15

    Every day, we encounter situations in which we have to deal with multiple response options. In order not to overstrain response selection resources, we need to cascade the associated task goals. Yet, the neurobiological foundations of these action cascading processes are largely unknown. Aiming at determining the possible relevance of the neuropeptide Y Y2 receptor for action cascading processes, this study investigates a functional promoter variation (rs2234759) in the neuropeptide Y Y2 receptor gene (NPY2R). 176 healthy subjects completed a stop-change paradigm. Applying mathematical constraints to the obtained behavioral data allowed for a classification of the action cascading processing mode on a serial to parallel continuum. Neurophysiological data (EEG) were analyzed along this mathematical constraint. The behavioral data show that the Y2-receptor high expression G allele is associated with a less efficient mode of action cascading where different task goals are activated in parallel. The neurophysiological data indicate that this effect is based on modulations at the response selection stage but not on changes in the preceding attentional selection processes. Analyses show that the interrelation between behavioral and neurophysiological data is mediated by genotype effects. At the level of response selection, genotype effects are associated with activity changes in the anterior cingulate cortex (ACC). Changes in the reliability of neural synchronization processes in the theta frequency band are also related to these effects. Possibly, these Y2-receptor-related effects emerge from the receptor's strong interrelation with the dopamine system. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. All passive architecture for high efficiency cascaded Raman conversion

    Science.gov (United States)

    Balaswamy, V.; Arun, S.; Chayran, G.; Supradeepa, V. R.

    2018-02-01

    Cascaded Raman fiber lasers have offered a convenient method to obtain scalable, high-power sources at various wavelength regions inaccessible with rare-earth doped fiber lasers. A limitation previously was the reduced efficiency of these lasers. Recently, new architectures have been proposed to enhance efficiency, but this came at the cost of enhanced complexity, requiring an additional low-power, cascaded Raman laser. In this work, we overcome this with a new, all-passive architecture for high-efficiency cascaded Raman conversion. We demonstrate our architecture with a fifth-order cascaded Raman converter from 1117nm to 1480nm with output power of ~64W and efficiency of 60%.

  1. Consolidation Waves

    OpenAIRE

    Berg, Ward; Smit, Han

    2007-01-01

    textabstractThis paper explains why consolidation acquisitions occur in waves and it predicts the differing role each firm is likely to play in the consolidation game. We propose that whether a firm assumes the role of rival consolidator, target, or passive observer depends on the position of the firm relative to the entity that merges first. Our model predicts that an initial acquisition triggers a wave of follow-on acquisitions, where the process of asset accumulation by the consolidator is...

  2. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Andersen, Thomas Lykke

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star....

  3. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star....

  4. Blast Waves

    CERN Document Server

    Needham, Charles E

    2010-01-01

    The primary purpose of this text is to document many of the lessons that have been learned during the author’s more than forty years in the field of blast and shock. The writing therefore takes on an historical perspective, in some sense, because it follows the author’s experience. The book deals with blast waves propagating in fluids or materials that can be treated as fluids. It begins by distinguishing between blast waves and the more general category of shock waves. It then examines several ways of generating blast waves, considering the propagation of blast waves in one, two and three dimensions as well as through the real atmosphere. One section treats the propagation of shocks in layered gases in a more detailed manner. The book also details the interaction of shock waves with structures in particular reflections, progressing from simple to complex geometries, including planar structures, two-dimensional structures such as ramps or wedges, reflections from heights of burst, and three-dimensional st...

  5. Cascading walks model for human mobility patterns.

    Science.gov (United States)

    Han, Xiao-Pu; Wang, Xiang-Wen; Yan, Xiao-Yong; Wang, Bing-Hong

    2015-01-01

    Uncovering the mechanism behind the scaling laws and series of anomalies in human trajectories is of fundamental significance in understanding many spatio-temporal phenomena. Recently, several models, e.g. the explorations-returns model (Song et al., 2010) and the radiation model for intercity travels (Simini et al., 2012), have been proposed to study the origin of these anomalies and the prediction of human movements. However, an agent-based model that could reproduce most of empirical observations without priori is still lacking. In this paper, considering the empirical findings on the correlations of move-lengths and staying time in human trips, we propose a simple model which is mainly based on the cascading processes to capture the human mobility patterns. In this model, each long-range movement activates series of shorter movements that are organized by the law of localized explorations and preferential returns in prescribed region. Based on the numerical simulations and analytical studies, we show more than five statistical characters that are well consistent with the empirical observations, including several types of scaling anomalies and the ultraslow diffusion properties, implying the cascading processes associated with the localized exploration and preferential returns are indeed a key in the understanding of human mobility activities. Moreover, the model shows both of the diverse individual mobility and aggregated scaling displacements, bridging the micro and macro patterns in human mobility. In summary, our model successfully explains most of empirical findings and provides deeper understandings on the emergence of human mobility patterns.

  6. Wave Generation Theory

    DEFF Research Database (Denmark)

    Frigaard, Peter; Høgedal, Michael; Christensen, Morten

    The intention of this manual is to provide some formulas and techniques which can be used for generating waves in hydraulic laboratories. Both long crested waves (2-D waves) and short crested waves (3-D waves) are considered....

  7. Quaternary Magmatism in the Cascades - Geologic Perspectives

    Science.gov (United States)

    Hildreth, Wes

    2007-01-01

    Foreward The Cascade magmatic arc is a belt of Quaternary volcanoes that extends 1,250 km from Lassen Peak in northern California to Meager Mountain in Canada, above the subduction zone where the Juan de Fuca Plate plunges beneath the North American Plate. This Professional Paper presents a synthesis of the entire volcanic arc, addressing all 2,300 known Quaternary volcanoes, not just the 30 or so visually prominent peaks that comprise the volcanic skyline. Study of Cascade volcanoes goes back to the geological explorers of the late 19th century and the seminal investigations of Howel Williams in the 1920s and 1930s. However, major progress and application of modern scientific methods and instrumentation began only in the 1970s with the advent of systematic geological, geophysical, and geochemical studies of the entire arc. Initial stimulus from the USGS Geothermal Research Program was enhanced by the USGS Volcano Hazards Program following the 1980 eruption of Mount St. Helens. Together, these two USGS Programs have provided more than three decades of stable funding, staffing, and analytical support. This Professional Paper summarizes the resultant USGS data sets and integrates them with the parallel contributions of other investigators. The product is based upon an all-encompassing and definitive geological database, including chemical and isotopic analyses to characterize the rocks and geochronology to provide the critical time constraints. Until now, this massive amount of data has not been summarized, and a systematic and uniform interpretation firmly grounded in geological fact has been lacking. Herein lies the primary utility of this Cascade volume. It not only will be the mandatory starting point for new workers, but also will provide essential geological context to broaden the perspectives of current investigators of specific Cascade volcanoes. Wes Hildreth's insightful understanding of volcanic processes and his uncompromising scientific integrity make him

  8. Bi-Directional Energy Cascades and the Origin of Kinetic Alfvénic and Whistler Turbulence in the Solar Wind

    Science.gov (United States)

    Goldstein, M. L.; Che, H.; Vinas, A. F.

    2014-12-01

    The observed ion-kinetic scale turbulence spectrum in the solar wind raises the question of how that turbulence originates. Observations of keV energetic electrons during solar quiet-time suggest them as possible source of free energy to drive the turbulence. Using particle-in-cell simulations, we explore how free energy in energetic electrons, released by an electron two-stream instability drives Weibel-like electromagnetic waves that excite wave-wave interactions. Consequently, both kinetic Alfvénic and whistler turbulence are excited that evolve through inverse and forward magnetic energy cascades.

  9. Low-threshold terahertz molecular laser optically pumped by a quantum cascade laser

    Directory of Open Access Journals (Sweden)

    A. Pagies

    2016-06-01

    Full Text Available We demonstrate a low-threshold, compact, room temperature, and continuous-wave terahertz molecular laser optically pumped by a mid-infrared quantum cascade laser. These characteristics are obtained, thanks to large dipole transitions of the active medium: NH3 (ammonia in gas state. The low-power (<60 mW laser pumping excites the molecules, thanks to intense mid-infrared transitions around 10.3 μm. The molecules de-excite by stimulated emission on pure inversion “umbrella-mode” quantum transitions allowed by the tunnel effect. The tunability of the quantum cascade laser gives access to several pure inversion transitions with different rotation states: we demonstrate the continuous-wave generation of ten laser lines around 1 THz. At 1.07 THz, we measure a power of 34 μW with a very low-threshold of 2 mW and a high differential efficiency of 0.82 mW/W. The spectrum was measured showing that the linewidth is lower than 1 MHz. To our knowledge, this is the first THz molecular laser pumped by a solid-state source and this result opens the way for compact, simple, and efficient THz source at room temperature for imaging applications.

  10. A sulfur hexafluoride sensor using quantum cascade and CO2 laser-based photoacoustic spectroscopy.

    Science.gov (United States)

    Rocha, Mila; Sthel, Marcelo; Lima, Guilherme; da Silva, Marcelo; Schramm, Delson; Miklós, András; Vargas, Helion

    2010-01-01

    The increase in greenhouse gas emissions is a serious environmental problem and has stimulated the scientific community to pay attention to the need for detection and monitoring of gases released into the atmosphere. In this regard, the development of sensitive and selective gas sensors has been the subject of several research programs. An important greenhouse gas is sulphur hexafluoride, an almost non-reactive gas widely employed in industrial processes worldwide. Indeed it is estimated that it has a radiative forcing of 0.52 W/m(2). This work compares two photoacoustic spectrometers, one coupled to a CO(2) laser and another one coupled to a Quantum Cascade (QC) laser, for the detection of SF(6). The laser photoacoustic spectrometers described in this work have been developed for gas detection at small concentrations. Detection limits of 20 ppbv for CO(2) laser and 50 ppbv for quantum cascade laser were obtained.

  11. A Pole-Zero Filter Cascade Provides Good Fits to Human Masking Data and to Basilar Membrane and Neural Data

    Science.gov (United States)

    Lyon, Richard F.

    2011-11-01

    A cascade of two-pole-two-zero filters with level-dependent pole and zero dampings, with few parameters, can provide a good match to human psychophysical and physiological data. The model has been fitted to data on detection threshold for tones in notched-noise masking, including bandwidth and filter shape changes over a wide range of levels, and has been shown to provide better fits with fewer parameters compared to other auditory filter models such as gammachirps. Originally motivated as an efficient machine implementation of auditory filtering related to the WKB analysis method of cochlear wave propagation, such filter cascades also provide good fits to mechanical basilar membrane data, and to auditory nerve data, including linear low-frequency tail response, level-dependent peak gain, sharp tuning curves, nonlinear compression curves, level-independent zero-crossing times in the impulse response, realistic instantaneous frequency glides, and appropriate level-dependent group delay even with minimum-phase response. As part of exploring different level-dependent parameterizations of such filter cascades, we have identified a simple sufficient condition for stable zero-crossing times, based on the shifting property of the Laplace transform: simply move all the s-domain poles and zeros by equal amounts in the real-s direction. Such pole-zero filter cascades are efficient front ends for machine hearing applications, such as music information retrieval, content identification, speech recognition, and sound indexing.

  12. Efficient Wave Energy Amplification with Wave Reflectors

    OpenAIRE

    Kramer, Morten Mejlhede; Frigaard, Peter Bak

    2002-01-01

    Wave Energy Converters (WEC's) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased to approximately 130-140%. In the paper a procedure for calculating the efficiency and optimizing the geometry of wave reflectors are described, this by use of a 3D boundary element method. The calculations are verified ...

  13. Eruptive history of South Sister, Oregon Cascades

    Science.gov (United States)

    Fierstein, J.; Hildreth, W.; Calvert, A.T.

    2011-01-01

    South Sister is southernmost and highest of the Three Sisters, three geologically dissimilar stratovolcanoes that together form a spectacular 20km reach along the Cascade crest in Oregon. North Sister is a monotonously mafic edifice as old as middle Pleistocene, Middle Sister a basalt-andesite-dacite cone built between 48 and 14ka, and South Sister is a basalt-free edifice that alternated rhyolitic and intermediate modes from 50ka to 2ka (largely contemporaneous with Middle Sister). Detailed mapping, 330 chemical analyses, and 42 radioisotopic ages show that the oldest exposed South Sister lavas were initially rhyolitic ~50ka. By ~37ka, rhyolitic lava flows and domes (72-74% SiO2) began alternating with radially emplaced dacite (63-68% SiO2) and andesite (59-63% SiO2) lava flows. Construction of a broad cone of silicic andesite-dacite (61-64% SiO2) culminated ~30ka in a dominantly explosive sequence that began with crater-forming andesitic eruptions that left fragmental deposits at least 200m thick. This was followed at ~27ka by growth of a steeply dipping summit cone of agglutinate-dominated andesite (56-60.5% SiO2) and formation of a summit crater ~800m wide. This crater was soon filled and overtopped by a thick dacite lava flow and then by >150m of dacitic pyroclastic ejecta. Small-volume dacite lavas (63-67% SiO2) locally cap the pyroclastic pile. A final sheet of mafic agglutinate (54-56% SiO2) - the most mafic product of South Sister - erupted from and drapes the small (300-m-wide) present-day summit crater, ending a summit-building sequence that lasted until ~22ka. A 20kyr-long-hiatus was broken by rhyolite eruptions that produced (1) the Rock Mesa coulee, tephra, and satellite domelets (73.5% SiO2) and (2) the Devils Chain of ~20 domes and short coulees (72.3-72.8% SiO2) from N-S vent alignments on South Sister's flanks. The compositional reversal from mafic summit agglutinate to recent rhyolites epitomizes the frequently changing compositional modes of the

  14. Temporal switching induced by cascaded third order nonlinearity

    DEFF Research Database (Denmark)

    Eilenberger, Falk; Bache, Morten; Minardi, Stefano

    2012-01-01

    We investigate the impact of cascaded third harmonic generation and the intrinsic n4 material nonlinearity on the propagation of ultrashort pulses in noble-gas filled Kagome fibers. We show that the pressure tunability of the cascade allows for the implementation of temporal switching. We also...... investigate the relative strengths of both effects and show their ratio to be pressure tunable....

  15. Cascade vulnerability for risk analysis of water infrastructure.

    Science.gov (United States)

    Sitzenfrei, R; Mair, M; Möderl, M; Rauch, W

    2011-01-01

    One of the major tasks in urban water management is failure-free operation for at least most of the time. Accordingly, the reliability of the network systems in urban water management has a crucial role. The failure of a component in these systems impacts potable water distribution and urban drainage. Therefore, water distribution and urban drainage systems are categorized as critical infrastructure. Vulnerability is the degree to which a system is likely to experience harm induced by perturbation or stress. However, for risk assessment, we usually assume that events and failures are singular and independent, i.e. several simultaneous events and cascading events are unconsidered. Although failures can be causally linked, a simultaneous consideration in risk analysis is hardly considered. To close this gap, this work introduces the term cascade vulnerability for water infrastructure. Cascade vulnerability accounts for cascading and simultaneous events. Following this definition, cascade risk maps are a merger of hazard and cascade vulnerability maps. In this work cascade vulnerability maps for water distribution systems and urban drainage systems based on the 'Achilles-Approach' are introduced and discussed. It is shown, that neglecting cascading effects results in significant underestimation of risk scenarios.

  16. A nine-level hybrid symmetric cascaded multilevel converter for ...

    Indian Academy of Sciences (India)

    Bridge (TCHB) power cell and one three-level H-bridge power cell with equal dc link voltages, and they are connected in cascade. Due to cascade connection and equal dc link voltage, the power shared by each power cell is nearly equal.

  17. Hybrid Modulation Scheme for Cascaded H-Bridge Inverter Cells ...

    African Journals Online (AJOL)

    This work proposes a switching technique for cascaded H-Bridge (CHB) cells. Single carrier Sinusoidal PWM (SCSPWM) scheme is employed in the generation of the gating signals. A sequential switching and base PWM circulation schemes are presented for this fundamental cascaded multilevel inverter topology.

  18. Influence of blood flow on the coagulation cascade

    DEFF Research Database (Denmark)

    The influence of diffusion and convetive flows on the blood coagulation cascade is investigated for a controlled perfusion experiment. We present a cartoon model and reaction schemes for parts of the coagulation cascade with sunsequent set up of a mathematical model in two space dimensions plus one...

  19. Seeking the northern boundary of the Cascade strawberry

    Science.gov (United States)

    Fragaria cascadensis K.E. Hummer, an endemic decaploid strawberry species, was described from the Oregon Cascade Mountains in the Pacific North-western United States. Its range occurs near Mt. Hood, the highest peak in the northern Oregon Cascades, in a band of higher elevation sites southwards to n...

  20. 36 CFR 7.66 - North Cascades National Park.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false North Cascades National Park. 7.66 Section 7.66 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.66 North Cascades National Park. (a...

  1. Intermittent Flow Regimes in a Transonic Fan Airfoil Cascade

    Directory of Open Access Journals (Sweden)

    J. Lepicovsky

    2004-01-01

    velocity.To date, this flow behavior has only been observed in a linear transonic cascade. Further research is necessary to confirm this phenomenon occurs in actual transonic fans and is not the by-product of an endwall restricted linear cascade.

  2. A modeling framework for system restoration from cascading failures.

    Science.gov (United States)

    Liu, Chaoran; Li, Daqing; Zio, Enrico; Kang, Rui

    2014-01-01

    System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems.

  3. Impedance Coordinative Control for Cascaded Converter in Bidirectional Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe

    2015-01-01

    Two stage cascaded converters are widely used in bidirectional applications, but the negative impedance may cause system instability. Actually the impedance interaction is much different between forward power flow and reversed power flow, which will introduce more uncertainty to the system...... stability. This paper proposes a control method for the constant power controlled converter in cascaded system, and consequently it can change the negative impedance of constant power converter into resistive impedance, which will improve the cascaded system stability, as well as merge the impedance...... difference between forward and reversed power flow. This paper addresses the analysis with the topology of cascaded dual-active-bridge converter (DAB) with inverter, and the proposed control method can also be implemented in unidirectional applications and other general cascaded converter system...

  4. A modeling framework for system restoration from cascading failures.

    Directory of Open Access Journals (Sweden)

    Chaoran Liu

    Full Text Available System restoration from cascading failures is an integral part of the overall defense against catastrophic breakdown in networked critical infrastructures. From the outbreak of cascading failures to the system complete breakdown, actions can be taken to prevent failure propagation through the entire network. While most analysis efforts have been carried out before or after cascading failures, restoration during cascading failures has been rarely studied. In this paper, we present a modeling framework to investigate the effects of in-process restoration, which depends strongly on the timing and strength of the restoration actions. Furthermore, in the model we also consider additional disturbances to the system due to restoration actions themselves. We demonstrate that the effect of restoration is also influenced by the combination of system loading level and restoration disturbance. Our modeling framework will help to provide insights on practical restoration from cascading failures and guide improvements of reliability and resilience of actual network systems.

  5. Modelling of Attenuation and Crosstalk of Cascaded Transmission Lines

    Directory of Open Access Journals (Sweden)

    Pavel Lafata

    2011-01-01

    Full Text Available This paper deals with the measurements and modelling of attenuation and near-end (NEXT and far-end (FEXT crosstalk for cascaded metallic transmission lines. The transmission parameters of homogenous metallic line can be easily described by telegraph equations or cascade matrix; there are also several models for NEXT and FEXT frequency dependence. But these models and equations could not be applied in the situation of two or more different cascaded transmission lines, because these cascaded lines do not meet the essential condition of overall homogenous transmission line. However in such case, it is still possible to estimate the overall transmission characteristics of the whole combination thanks to the characteristics of each separate element. This paper brings the description of complex measurements performed for the combination of three different metallic cables and based on these measurements, several conclusions about the possibilities of modelling the attenuation and NEXT and FEXT crosstalk for cascaded transmission lines are presented.

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

    CERN Document Server

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

    2014-01-01

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

  7. Quantum cascade laser FM spectroscopy of explosives

    Science.gov (United States)

    Gutmann, Zach; Clasp, Trocia; Lue, Chris; Johnson, Tiffani; Ingle, Taylor; Jamison, Janet; Buchanan, Roger; Reeve, Scott

    2013-05-01

    Polyisobutylene is an industrial polymer that is widely used in a number of applications including the manufacture of military grade explosives. We have examined the vapor emanating from a series of different molecular weight samples of polyisobutylene using high resolution Quantum Cascade Laser FM spectroscopy. The vapor phase spectra all exhibit a rovibrational structure similar to that for the gas phase isobutylene molecule. We have assigned the structure in the 890 cm-1 and 1380 cm-1 regions to the isobutylene ν28 and ν7 fundamental bands respectively. These spectroscopic signatures may prove useful for infrared sensing applications. Here we will present the infrared signatures along with recent GCMS data from a sample of C4, utilizing solid-phase microextraction vapor collection fibers, which confirm the presence of isobutylene as one of the volatile bouquet species in RDX-based explosives.

  8. Control of cascaded induction generator systems

    Science.gov (United States)

    Ortmeyer, T. H.

    1984-12-01

    This report documents an investigation of the stability and control of cascaded doubly fed machines (CDFM). These machines are brushless variable speed constant frequency electric power generators with potential for application in aircraft. A previous analytical study indicated the CDFM system would be controllable in the subsynchronous operating mode with a passive RL load. The present study contains two steps. First is an investigation of the machine operation in the supersynchronous mode. The second step is an investigation of machine operation with output capacitors providing excitation VARs for the machine and load. Step 1 results show that the machines exhibit stability characteristics in the supersynchronous mode similar to those observed in the subsynchronous mode. Step 2 results show that output capacitors degrade the system performance, particularly at light loads. The results show that output current feedback can be employed to improve the system performance.

  9. Cascaded face alignment via intimacy definition feature

    Science.gov (United States)

    Li, Hailiang; Lam, Kin-Man; Chiu, Man-Yau; Wu, Kangheng; Lei, Zhibin

    2017-09-01

    Recent years have witnessed the emerging popularity of regression-based face aligners, which directly learn mappings between facial appearance and shape-increment manifolds. We propose a random-forest based, cascaded regression model for face alignment by using a locally lightweight feature, namely intimacy definition feature. This feature is more discriminative than the pose-indexed feature, more efficient than the histogram of oriented gradients feature and the scale-invariant feature transform feature, and more compact than the local binary feature (LBF). Experimental validation of our algorithm shows that our approach achieves state-of-the-art performance when testing on some challenging datasets. Compared with the LBF-based algorithm, our method achieves about twice the speed, 20% improvement in terms of alignment accuracy and saves an order of magnitude on memory requirement.

  10. Cascaded Amplitude Modulations in Sound Texture Perception

    DEFF Research Database (Denmark)

    McWalter, Richard Ian; Dau, Torsten

    2017-01-01

    Sound textures, such as crackling fire or chirping crickets, represent a broad class of sounds defined by their homogeneous temporal structure. It has been suggested that the perception of texture is mediated by time-averaged summary statistics measured from early auditory representations....... In this study, we investigated the perception of sound textures that contain rhythmic structure, specifically second-order amplitude modulations that arise from the interaction of different modulation rates, previously described as "beating" in the envelope-frequency domain. We developed an auditory texture...... model that utilizes a cascade of modulation filterbanks that capture the structure of simple rhythmic patterns. The model was examined in a series of psychophysical listening experiments using synthetic sound textures-stimuli generated using time-averaged statistics measured from real-world textures...

  11. Cascaded Quadratic Soliton Compression in Waveguide Structures

    DEFF Research Database (Denmark)

    Guo, Hairun

    between the Kerr nonlinear effects and the dispersive effects in the medium. A Kerr-like nonlinearity is produced through the cascaded phase mismatched quadratic process, e.g. the second harmonic generation process, which can be flexibly tuned in both the sign and the amplitude, making possible a strong...... and self-defocusing Kerr effect so that the soliton is created and the soliton self-compression happens in the normal dispersion region. Meanwhile, the chromatic dispersion in the waveguide is also tunable, understood as the dispersion engineering with structural designs. Therefore, compared to commonly......-focusing Kerr effects when under the self-defocusing regime. On the other hand, CQSC in quadratic waveguides seems highly complementary to that in quadratic bulk crystals. With bulk crystals dealing with high-energy, low-repetition-rate and large-beam-size pulses, quadratic waveguides could operate low...

  12. Cascaded FSO-VLC Communication System

    KAUST Repository

    Gupta, Akash

    2017-08-28

    The proposed cascaded free space optics (FSO)-visible light communication (VLC) system consists of multiple VLC access points which caters the end users connected via a decode and forward (DF) relay to the FSO backhaul link. The FSO link is assumed to be affected by path-loss, pointing error and atmospheric turbulence while the end-to-end signal-to-noise ratio (SNR) of VLC downlinks are statistically characterized considering the randomness of users position. In this study, the novel closed form expressions of the statistics like probability density function (PDF) and cumulative distribution function (CDF) of the equivalent SNR are derived. Capitalizing on these, the closed form expressions for various performance metrics such as outage probability and error probability are provided. The simulation results are provided to verify the functional curves of mathematical analysis.

  13. Information propagation in a noisy gene cascade

    Science.gov (United States)

    Monteoliva, D.; Diambra, L.

    2017-07-01

    We use information theory to study the information transmission through a simple gene cascade where the product of an unregulated gene regulates the expression activity of a cooperative genetic switch. While the input signal is provided by the upstream gene with two states, we consider that the expression of downstream gene is controlled by a cis-regulatory system with three binding sites for the regulator product, which can bind cooperatively. By computing exactly the associated probability distributions, we estimate information transmission thought the mutual information measure. We found that the mutual information associated with unimodal input signal is lower than the associated with bimodal inputs. We also observe that mutual information presents a maximum in the cooperativity intensity, and the position of this maximum depends on the kinetic rates of the promoter. Furthermore, we found that the bursting dynamics of the input signal can enhance the information transmission capacity.

  14. Book review: Extreme ocean waves

    Science.gov (United States)

    Geist, Eric L.

    2017-01-01

    “Extreme Ocean Waves”, edited by E. Pelinovsky and C. Kharif, second edition, Springer International Publishing, 2016; ISBN: 978-3-319-21574-7, ISBN (eBook): 978-3-319-21575-4The second edition of “Extreme Ocean Waves” published by Springer is an update of a collection of 12 papers edited by Efim Pelinovsky and Christian Kharif following the April 2007 meeting of the General Assembly of the European Geosciences Union. In this edition, three new papers have been added and three more have been substantially revised. Color figures are now included, which greatly aids in reading several of the papers, and is especially helpful in visualizing graphs as in the paper on symbolic computation of nonlinear wave resonance (Tobisch et al.). A note on terminology: extreme waves in this volume broadly encompass different types of waves, including deep-water and shallow-water rogue waves (which are alternatively termed freak waves), and internal waves. One new paper on tsunamis (Viroulet et al.) is now included in the second edition of this volume. Throughout the book, the reader will find a combination of laboratory, theoretical, and statistical/empirical treatment necessary for the complete examination of this subject. In the Introduction, the editors underscore the importance of studying extreme waves, documenting a dramatic instance of damaging extreme waves that recently occurred in 2014.

  15. Fluctuation sensitivity of a transcriptional signaling cascade

    Science.gov (United States)

    Pilkiewicz, Kevin R.; Mayo, Michael L.

    2016-09-01

    The internal biochemical state of a cell is regulated by a vast transcriptional network that kinetically correlates the concentrations of numerous proteins. Fluctuations in protein concentration that encode crucial information about this changing state must compete with fluctuations caused by the noisy cellular environment in order to successfully transmit information across the network. Oftentimes, one protein must regulate another through a sequence of intermediaries, and conventional wisdom, derived from the data processing inequality of information theory, leads us to expect that longer sequences should lose more information to noise. Using the metric of mutual information to characterize the fluctuation sensitivity of transcriptional signaling cascades, we find, counter to this expectation, that longer chains of regulatory interactions can instead lead to enhanced informational efficiency. We derive an analytic expression for the mutual information from a generalized chemical kinetics model that we reduce to simple, mass-action kinetics by linearizing for small fluctuations about the basal biological steady state, and we find that at long times this expression depends only on a simple ratio of protein production to destruction rates and the length of the cascade. We place bounds on the values of these parameters by requiring that the mutual information be at least one bit—otherwise, any received signal would be indistinguishable from noise—and we find not only that nature has devised a way to circumvent the data processing inequality, but that it must be circumvented to attain this one-bit threshold. We demonstrate how this result places informational and biochemical efficiency at odds with one another by correlating high transcription factor binding affinities with low informational output, and we conclude with an analysis of the validity of our assumptions and propose how they might be tested experimentally.

  16. Cascading walks model for human mobility patterns.

    Directory of Open Access Journals (Sweden)

    Xiao-Pu Han

    Full Text Available Uncovering the mechanism behind the scaling laws and series of anomalies in human trajectories is of fundamental significance in understanding many spatio-temporal phenomena. Recently, several models, e.g. the explorations-returns model (Song et al., 2010 and the radiation model for intercity travels (Simini et al., 2012, have been proposed to study the origin of these anomalies and the prediction of human movements. However, an agent-based model that could reproduce most of empirical observations without priori is still lacking.In this paper, considering the empirical findings on the correlations of move-lengths and staying time in human trips, we propose a simple model which is mainly based on the cascading processes to capture the human mobility patterns. In this model, each long-range movement activates series of shorter movements that are organized by the law of localized explorations and preferential returns in prescribed region.Based on the numerical simulations and analytical studies, we show more than five statistical characters that are well consistent with the empirical observations, including several types of scaling anomalies and the ultraslow diffusion properties, implying the cascading processes associated with the localized exploration and preferential returns are indeed a key in the understanding of human mobility activities. Moreover, the model shows both of the diverse individual mobility and aggregated scaling displacements, bridging the micro and macro patterns in human mobility. In summary, our model successfully explains most of empirical findings and provides deeper understandings on the emergence of human mobility patterns.

  17. Orexin/hypocretin receptor signalling cascades.

    Science.gov (United States)

    Kukkonen, J P; Leonard, C S

    2014-01-01

    Orexin (hypocretin) peptides and their two known G-protein-coupled receptors play essential roles in sleep-wake control and powerfully influence other systems regulating appetite/metabolism, stress and reward. Consequently, drugs that influence signalling by these receptors may provide novel therapeutic opportunities for treating sleep disorders, obesity and addiction. It is therefore critical to understand how these receptors operate, the nature of the signalling cascades they engage and their physiological targets. In this review, we evaluate what is currently known about orexin receptor signalling cascades, while a sister review (Leonard & Kukkonen, this issue) focuses on tissue-specific responses. The evidence suggests that orexin receptor signalling is multifaceted and is substantially more diverse than originally thought. Indeed, orexin receptors are able to couple to members of at least three G-protein families and possibly other proteins, through which they regulate non-selective cation channels, phospholipases, adenylyl cyclase, and protein and lipid kinases. In the central nervous system, orexin receptors produce neuroexcitation by postsynaptic depolarization via activation of non-selective cation channels, inhibition of K⁺ channels and activation of Na⁺/Ca²⁺ exchange, but they also can stimulate the release of neurotransmitters by presynaptic actions and modulate synaptic plasticity. Ca²⁺ signalling is also prominently influenced by these receptors, both via the classical phospholipase C-Ca²⁺ release pathway and via Ca²⁺ influx, mediated by several pathways. Upon longer-lasting stimulation, plastic effects are observed in some cell types, while others, especially cancer cells, are stimulated to die. Thus, orexin receptor signals appear highly tunable, depending on the milieu in which they are operating. © 2013 The British Pharmacological Society.

  18. Finite Amplitude Ocean Waves

    Indian Academy of Sciences (India)

    IAS Admin

    (2). Hence, small amplitude waves are also called linear waves. Most of the aspects of the ocean waves can be explained by the small amplitude wave theory. Let us now see the water particle motion due to waves. While wave energy is carried by the wave as it progresses forward, the water particles oscillate up and down.

  19. Wave groups in unidirectional surface wave models

    NARCIS (Netherlands)

    van Groesen, Embrecht W.C.

    1998-01-01

    Uni-directional wave models are used to study wave groups that appear in wave tanks of hydrodynamic laboratories; characteristic for waves in such tanks is that the wave length is rather small, comparable to the depth of the layer. In second-order theory, the resulting Nonlinear Schrödinger (NLS)

  20. Flow-dependent mass transfer may trigger endothelial signaling cascades.

    Science.gov (United States)

    Vandrangi, Prashanthi; Sosa, Martha; Shyy, John Y-J; Rodgers, Victor G J

    2012-01-01

    It is well known that fluid mechanical forces directly impact endothelial signaling pathways. But while this general observation is clear, less apparent are the underlying mechanisms that initiate these critical signaling processes. This is because fluid mechanical forces can offer a direct mechanical input to possible mechanotransducers as well as alter critical mass transport characteristics (i.e., concentration gradients) of a host of chemical stimuli present in the blood stream. However, it has recently been accepted that mechanotransduction (direct mechanical force input), and not mass transfer, is the fundamental mechanism for many hemodynamic force-modulated endothelial signaling pathways and their downstream gene products. This conclusion has been largely based, indirectly, on accepted criteria that correlate signaling behavior and shear rate and shear stress, relative to changes in viscosity. However, in this work, we investigate the negative control for these criteria. Here we computationally and experimentally subject mass-transfer limited systems, independent of mechanotransduction, to the purported criteria. The results showed that the negative control (mass-transfer limited system) produced the same trends that have been used to identify mechanotransduction-dominant systems. Thus, the widely used viscosity-related shear stress and shear rate criteria are insufficient in determining mechanotransduction-dominant systems. Thus, research should continue to consider the importance of mass transfer in triggering signaling cascades.

  1. The 2016 Kumamoto Earthquakes: Cascading Geological Hazards and Compounding Risks

    Directory of Open Access Journals (Sweden)

    Katsuichiro Goda

    2016-08-01

    Full Text Available A sequence of two strike-slip earthquakes occurred on 14 and 16 April 2016 in the intraplate region of Kyushu Island, Japan, apart from subduction zones, and caused significant damage and disruption to the Kumamoto region. The analyses of regional seismic catalog and available strong motion recordings reveal striking characteristics of the events, such as migrating seismicity, earthquake surface rupture, and major foreshock-mainshock earthquake sequences. To gain valuable lessons from the events, a UK Earthquake Engineering Field Investigation Team (EEFIT was dispatched to Kumamoto, and earthquake damage surveys were conducted to relate observed earthquake characteristics to building and infrastructure damage caused by the earthquakes. The lessons learnt from the reconnaissance mission have important implications on current seismic design practice regarding the required seismic resistance of structures under multiple shocks and the seismic design of infrastructure subject to large ground deformation. The observations also highlight the consequences of cascading geological hazards on community resilience. To share the gathered damage data widely, geo-tagged photos are organized using Google Earth and the kmz file is made publicly available.

  2. Complex interdependent supply chain networks: Cascading failure and robustness

    Science.gov (United States)

    Tang, Liang; Jing, Ke; He, Jie; Stanley, H. Eugene

    2016-02-01

    A supply chain network is a typical interdependent network composed of an undirected cyber-layer network and a directed physical-layer network. To analyze the robustness of this complex interdependent supply chain network when it suffers from disruption events that can cause nodes to fail, we use a cascading failure process that focuses on load propagation. We consider load propagation via connectivity links as node failure spreads through one layer of an interdependent network, and we develop a priority redistribution strategy for failed loads subject to flow constraint. Using a giant component function and a one-to-one directed interdependence relation between nodes in a cyber-layer network and physical-layer network, we construct time-varied functional equations to quantify the dynamic process of failed loads propagation in an interdependent network. Finally, we conduct a numerical simulation for two cases, i.e., single node removal and multiple node removal at the initial disruption. The simulation results show that when we increase the number of removed nodes in an interdependent supply chain network its robustness undergoes a first-order discontinuous phase transition, and that even removing a small number of nodes will cause it to crash.

  3. Wave Dragon

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    På foranledning af Löwenmark F.R.I, er der udført numeriske beregninger af Wave Dragons (herefter WD) armes effektivitet for forskellige geometriske udformninger. 5 geometriske modeller, hvor WD's arme er forkortet/forlænget er undersøgt for 3 forskellige drejninger af armene. I alt er 15...

  4. Acoustic detection of ultra-high energy cascades in ice

    Energy Technology Data Exchange (ETDEWEB)

    Boeser, S.

    2006-12-08

    Current underwater optical neutrino telescopes are designed to detect neutrinos from astrophysical sources with energies in the TeV range. Due to the low fluxes and small cross sections, no high energy neutrinos of extraterrestrial origin have been observed so far. Only the Cherenkov neutrino detectors on the km{sup 3} scale that are currently under construction will have the necessary volume to observe these rare interactions. For the guaranteed source of neutrinos from interactions of the ultra-high energy cosmic at EeV energies rays with the ambient cosmic microwave background, event rates of only one per year are expected in these experiments. To measure the flux and verify the predicted cross sections of these cosmogenic neutrinos, an observed volume of the order of 100 km{sup 3} will be necessary, that will not be feasible with existing detection techniques. Alternative methods are required to build a detector on these scales. One promising idea is to record the acoustic waves generated in hadronic or electromagnetic cascades following the neutrino interaction. The higher amplitudes of the sonic signal and the large expected absorption length of sound favour South Polar ice instead of sea water as a medium. The prerequisites for an estimate of the potential of such a detector are suitable acoustic sensors, a verification of the model of thermo-acoustic sound generation and a determination of the acoustic properties of the ice. In a theoretical derivation the mechanism of thermo-elastic excitation of acoustic waves was shown to be equivalent for isotropic solids and liquids. Following a detailed analysis of the existing knowledge a simulation study of a hybrid optical-radio-acoustic detector has been performed. Ultrasonic sensors dedicated to in-ice application were developed and have been used to record acoustic signals from intense proton and laser beams in water and ice. With the obtained experience, the hitherto largest array of acoustic sensors and

  5. Cascade Version 1: Theory and Model Formulation

    Science.gov (United States)

    2006-06-01

    that provides this modeling framework , potentially allowing for an arbitrary number of scales. The coupling between coastal evolution at different...breakpoint. The two equations are written as follows: 2 2cos coso go o b gb bH C H Cθ = θ (7) sin sino b o bC C θ θ= (8) where H = wave height

  6. Integrated analysis of energy transfers in elastic-wave turbulence.

    Science.gov (United States)

    Yokoyama, Naoto; Takaoka, Masanori

    2017-08-01

    In elastic-wave turbulence, strong turbulence appears in small wave numbers while weak turbulence does in large wave numbers. Energy transfers in the coexistence of these turbulent states are numerically investigated in both the Fourier space and the real space. An analytical expression of a detailed energy balance reveals from which mode to which mode energy is transferred in the triad interaction. Stretching energy excited by external force is transferred nonlocally and intermittently to large wave numbers as the kinetic energy in the strong turbulence. In the weak turbulence, the resonant interactions according to the weak turbulence theory produce cascading net energy transfer to large wave numbers. Because the system's nonlinearity shows strong temporal intermittency, the energy transfers are investigated at active and moderate phases separately. The nonlocal interactions in the Fourier space are characterized by the intermittent bundles of fibrous structures in the real space.

  7. Cascade dams influence on sediment characteristics and phosphorus distribution.

    Science.gov (United States)

    Rapin, Anne; Mourier, Brice; Rabiet, Marion; Malgorzata, Grybos; Kestens, Tim; Deluchat, Veronique

    2017-04-01

    Massive river artificialisation by dam construction, responding to the steadily increasing human demand of water and electricity leads to several environmental consequences, including alteration of hydrological dynamic and sediment discontinuity. Important decreases of water flows and sediment transport downstream impact phosphorus (P) flux to the ocean and its cycle, due to P sediment storage in dam reservoir. Moreover, the release of P from sediments may enhance eutrophication processes in dam reservoir. Our study focused on the influence of cascade dams on physical and chemical characteristics of sediments and particularly on P sedimentary speciation along river continuum. Considering these results, the potential of P release from dam reservoir sediments was appraised and compared to un-impacted river parts. In addition, key parameters controlling P release at sediment/water interface were evaluated. Champsanglard, Chézelles and Age are three consecutive hydroelectric reservoirs on Creuse River (France; respective surfaces area of 55 ha, 23 ha, 38 ha and approximative height of 20 m each) subjected to seasonal cyanobacterial blooms. Surface sediments (17 samples) were collected in dams and free-flow river sections (on a stretch of 17 km); chemical composition (Fe, Al, Ca, Mn and P), organic matter (OM) content, particle size distribution and P fractionation were analysed. An abrupt change in sediment granulometry from a coarse-medium sand to silt texture going through free-flow river to dam reservoirs was observed. The same assessment was made in regard to OM content (from 3 ± 3% in river parts to 18 ± 3% in dams) and total P (0.27 ± 0.11 mgP/g DW in river parts to 1.8 ± 0.3 mgP/gDW in dams). P enrichment in sediment from dam reservoir is due to the retention of fine size particles. Relation between total P content and sediment grain size within each dam reservoir highlighted the role of slowdown river flow occurring in dams. In Champsanglard reservoir

  8. Carbon dioxide/methanol conversion cycle based on cascade enzymatic reactions supported on superparamagnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    CATERINA G.C. MARQUES NETTO

    2017-10-01

    Full Text Available ABSTRACT The conversion of carbon dioxide into important industrial feedstock is a subject of growing interest in modern society. A possible way to achieve this goal is by carrying out the CO2/methanol cascade reaction, allowing the recycle of CO2 using either chemical catalysts or enzymes. Efficient and selective reactions can be performed by enzymes; however, due to their low stability, immobilization protocols are required to improve their performance. The cascade reaction to reduce carbon dioxide into methanol has been explored by the authors, using, sequentially, alcohol dehydrogenase (ADH, formaldehyde dehydrogenase (FalDH, and formate dehydrogenase (FDH, powered by NAD+/NADH and glutamate dehydrogenase (GDH as the co-enzyme regenerating system. All the enzymes have been immobilized on functionalized magnetite nanoparticles, and their reactions investigated separately in order to establish the best performance conditions. Although the stepwise scheme led to only 2.3% yield of methanol per NADH; in a batch system under CO2 pressure, the combination of the four immobilized enzymes increased the methanol yield by 64 fold. The studies indicated a successful regeneration of NADH in situ, envisaging a real possibility of using immobilized enzymes to perform the cascade CO2-methanol reaction.

  9. Normalized-Mutual-Information-Based Mining Method for Cascading Patterns

    Directory of Open Access Journals (Sweden)

    Cunjin Xue

    2016-09-01

    Full Text Available A cascading pattern is a sequential pattern characterized by an item following another item in order. Recent research has investigated a challenge of dealing with cascading patterns, namely, the exponential time dependence of database scanning with respect to the number of items involved. We propose a normalized-mutual-information-based mining method for cascading patterns (M3Cap to address this challenge. M3Cap embeds mutual information to reduce database-scanning time. First, M3Cap calculates the asymmetrical mutual information between items with one database scan and extracts pair-wise related items according to a user-specified information threshold. Second, a one-level cascading pattern is generated by scanning the database once for each pair-wise related item at the quantitative level. Third, a recursive linking–pruning–generating loop generates an (m + 1-level-candidate cascading pattern from m-dimensional patterns on the basis of antimonotonicity and non-additivity, repeating this step until no further candidate cascading patterns are generated. Fourth, meaningful cascading patterns are generated according to user-specified minimum evaluation indicators. Finally, experiments with remote sensing image datasets covering the Pacific Ocean demonstrate that the computation time of recursive linking and pruning is significantly less than that of database scanning; thus, M3Cap improves performance by reducing database scanning while increasing intensive computing.

  10. Out of control: Fluctuation of cascading dynamics in networks

    Science.gov (United States)

    Wang, Jianwei; Cai, Lin; Xu, Bo; Li, Peng; Sun, Enhui; Zhu, Zhiguo

    2016-11-01

    Applying two preferential selection mechanisms of flow destination, we develop two new methods to quantify the initial load of a node, where the flow is transported along the shortest path between two nodes. We propose a simple cascading model and study cascading dynamics induced by attacking the node with the highest load in some synthetic and actual networks. Surprisingly, we observe the abnormal fluctuation of cascading dynamics, i.e., more damage can be triggered if we spend significantly higher cost to protect a network. In particular, this phenomenon is independent of the initial flow distribution and the preferential selection mechanisms of flow destination. However, it remains unclear which specific structural patterns may affect the fluctuation of cascading dynamics. In this paper, we examine the local evolution of the cascading propagation by constructing some special networks. We show that revivals of some nodes in the double ring structure facilitate the transportation of the flow between two unconnected sub-networks, cause more damage and subsequently lead to the abnormal fluctuation of cascading dynamics. Compared with the traditional definition of the betweenness, we adopt two new proposed methods to further evaluate the resilience of several actual networks. We find that some real world networks reach the strongest resilience level against cascading failures in our preferential selection mechanisms of flow destination. Moreover, we explore how to use the minimum cost to maximize the resilience of the studied networks.

  11. Theory of inertial waves in rotating fluids

    Science.gov (United States)

    Gelash, Andrey; L'vov, Victor; Zakharov, Vladimir

    2017-04-01

    The inertial waves emerge in the geophysical and astrophysical flows as a result of Earth rotation [1]. The linear theory of inertial waves is known well [2] while the influence of nonlinear effects of wave interactions are subject of many recent theoretical and experimental studies. The three-wave interactions which are allowed by inertial waves dispersion law (frequency is proportional to cosine of the angle between wave direction and axes of rotation) play an exceptional role. The recent studies on similar type of waves - internal waves, have demonstrated the possibility of formation of natural wave attractors in the ocean (see [3] and references herein). This wave focusing leads to the emergence of strong three-wave interactions and subsequent flows mixing. We believe that similar phenomena can take place for inertial waves in rotating flows. In this work we present theoretical study of three-wave and four-wave interactions for inertial waves. As the main theoretical tool we suggest the complete Hamiltonian formalism for inertial waves in rotating incompressible fluids [4]. We study three-wave decay instability and then present statistical description of inertial waves in the frame of Hamiltonian formalism. We obtain kinetic equation, anisotropic wave turbulence spectra and study the problem of parametric wave turbulence. These spectra were previously found in [5] by helicity decomposition method. Taking this into account we discuss the advantages of suggested Hamiltonian formalism and its future applications. Andrey Gelash thanks support of the RFBR (Grant No.16-31-60086 mol_a_dk) and Dr. E. Ermanyuk, Dr. I. Sibgatullin for the fruitful discussions. [1] Le Gal, P. Waves and instabilities in rotating and stratified flows, Fluid Dynamics in Physics, Engineering and Environmental Applications. Springer Berlin Heidelberg, 25-40, 2013. [2] Greenspan, H. P. The theory of rotating fluids. CUP Archive, 1968. [3] Brouzet, C., Sibgatullin, I. N., Scolan, H., Ermanyuk, E

  12. Aerodynamics of Cascaded Airfoils Oscillating or Subject to Three-Dimensional Periodic Gusts.

    Science.gov (United States)

    1980-01-01

    enhanced by higher blade loading and increased flow speed. This creates many new problems in fluid mechanics, aerodynamics, and aeroelasticity. For...interaction between the fluid mechanics, the aerodynamics, and the structural dynamics of the blading systems. The main objective of our research was to...Aeroelasticity in Turbomachines, Revue Frandoise de Mecanique , Special Volume, pp. 97-1104, October 1976, Paris, France. 4. Carta, F.O. and St. Hilaire, A.O

  13. Heat stress in urban areas: Indoor and outdoor temperatures in different urban structure types and subjectively reported well-being during a heat wave in the city of Leipzig

    Directory of Open Access Journals (Sweden)

    Ulrich Franck

    2013-04-01

    Full Text Available Climate projections for Leipzig suggest elevated minimum and maximum temperatures as well as more frequent days with high temperatures. Hence, climate change is threatening human well-being and health. People spend the majority of their time indoors. Therefore, indoor temperatures (especially during the night are of special importance with respect to well-being and health. Indoor air temperature depends on outdoor air temperatures, but is for example modified by type of urban structure, housing area, and may be also influenced by differences in the behavior of the inhabitants. Especially in cities, outdoor air temperatures depend on urban structure e.g. housing density, building arrangement, unpaved areas, types of urban structures, urban green, and other factors. Hence, the questions arise how types of urban structures are related to inner-urban temperature differences and how outdoor air temperatures influence indoor temperatures in dependence on urban housing conditions. This work is a part of a pilot study conducted during the summer 2010 which gathered data from remote sensing, mobile measurements, stationary measurements of air temperatures and relative humidity in areas with different housing structures, and of indoor as well as outdoor temperatures in occupied apartments. Household-survey data reported the subjective perception of heat stress. The study resulted in rather complex relationships between type of housing areas, indoor and outdoor temperatures, morning and evening temperatures, indoor and outdoor temperatures as well as subjective heat perception. Green spaces and types of residential areas are related to air temperatures. More green resulted in lower temperatures. Temperatures have a tendency to increase with increasing story number and are significantly higher in the top floor. An indoor heat island effect corresponding to the outdoor effect could be shown for the homes: Distance to city center is a predicting variable for

  14. Production of Alfven Daughter Waves Through Nonlinear Interactions of Counterpropagating Alfven Waves

    Science.gov (United States)

    Hamilton, David; Dorfman, Seth; Howes, Gregory; Carter, Troy

    2017-10-01

    The current theoretical understanding of astrophysical turbulence is based largely upon the nonlinear interactions between counterpropagating Alfven waves. These interactions are the fundamental building block used to model energy transfer from large to small scales. We present current experimental findings obtained in a laboratory plasma at the Large Plasma Device (LAPD), in which counterpropagating Alfven waves with crossed polarizations interacted with each other after being generated by antennas at the two ends of the device. This work is largely based off of previous efforts conducted at the LAPD by G. G. Howes, et al., but with differing key parameters, such as the amplitudes and frequencies of the two waves. We expect to find a daughter wave produced by the nonlinear interactions of the two parent waves. Additionally, ongoing analysis may reveal the same phenomenon to occur between the main daughter wave and either of the two parent waves; this effect has not yet been observed in the laboratory. This work may assist in furthering our understanding of the energy cascade effect in astrophysical turbulence. This work was performed at UCLA's Basic Plasma Science Facility, which is supported by the DOE and NSF.

  15. Light Diffraction by Large Amplitude Ultrasonic Waves in Liquids

    Science.gov (United States)

    Adler, Laszlo; Cantrell, John H.; Yost, William T.

    2016-01-01

    Light diffraction from ultrasound, which can be used to investigate nonlinear acoustic phenomena in liquids, is reported for wave amplitudes larger than that typically reported in the literature. Large amplitude waves result in waveform distortion due to the nonlinearity of the medium that generates harmonics and produces asymmetries in the light diffraction pattern. For standing waves with amplitudes above a threshold value, subharmonics are generated in addition to the harmonics and produce additional diffraction orders of the incident light. With increasing drive amplitude above the threshold a cascade of period-doubling subharmonics are generated, terminating in a region characterized by a random, incoherent (chaotic) diffraction pattern. To explain the experimental results a toy model is introduced, which is derived from traveling wave solutions of the nonlinear wave equation corresponding to the fundamental and second harmonic standing waves. The toy model reduces the nonlinear partial differential equation to a mathematically more tractable nonlinear ordinary differential equation. The model predicts the experimentally observed cascade of period-doubling subharmonics terminating in chaos that occurs with increasing drive amplitudes above the threshold value. The calculated threshold amplitude is consistent with the value estimated from the experimental data.

  16. An Improved Phase Disposition SPWM Strategy for Cascaded Multilevel Inverter

    Directory of Open Access Journals (Sweden)

    Jinbang Xu

    2014-01-01

    Full Text Available The Carrier Phase Shifted (CPS strategy is conventional for cascaded multilevel inverter, because it can naturally ensure all cascaded cells to output balanced power. However, in point of spectra of the output line voltage, CPS is suboptimal to Phase Disposition (PD strategy, because the latter can not naturally ensure power balance. This paper presents an improved PD strategy, inspiration from the disposition of CPS strategy triangle carriers. Just reconstructing the triangle carriers of PD strategy, it can not only reserve the waveform quality of the line voltage to be optimal, but also naturally ensure the output power of each cascaded cells to be balanced.

  17. Revised tephra volumes for Cascade Range volcanoes

    Science.gov (United States)

    Nathenson, Manuel

    2017-01-01

    Isopach maps from tephra eruptions from Mount St. Helens were reported in Carey et al. (1995) and for tephra eruptions from Glacier Peak in Gardner et al. (1998). For exponential thinning, the isopach data only define a single slope on a log thickness versus square root of area plot. Carey et al. (1995) proposed a model that was used to estimate a second slope, and volumes were presented in both studies using this model. A study by Sulpizio (2005) for estimating the second slope and square root of area where the lines intersect involves a systematic analysis of many eruptions to provide correlation equations. The purpose of this paper is to recalculate the volumes of Cascades eruptions and compare results from the two methods. In order to gain some perspective on the methods for estimating the second slope, we use data for thickness versus distance beyond the last isopach that are available for some of the larger eruptions in the Cascades. The thickness versus square root of area method is extended to thickness versus distance by developing an approximate relation between the two assuming elliptical isopachs with the source at one of the foci. Based on the comparisons made between the Carey et al. (1995) and Sulpizio (2005) methods, it is felt that the later method provides a better estimate of the second slope. For Mount St. Helens, the estimates of total volume using the Sulpizio (2005) method are generally smaller than those using the Carey et al. (1995) method. For the volume estimates of Carey et al. (1995), the volume of the May 18, 1980, eruption of Mount St. Helens is smaller than six of the eight previous eruptions. With the new volumes using the Sulpizio (2005) method, the 1980 eruption is smaller in volume than the upper end of the range for only three of the layers (Wn, Ye, and Yn) and is the same size as layer We. Thus the 1980 eruption becomes representative of the mid-range of volumes rather than being in the lower range.

  18. Gravitational waves

    CERN Document Server

    Ciufolini, I; Moschella, U; Fre, P

    2001-01-01

    Gravitational waves (GWs) are a hot topic and promise to play a central role in astrophysics, cosmology, and theoretical physics. Technological developments have led us to the brink of their direct observation, which could become a reality in the coming years. The direct observation of GWs will open an entirely new field: GW astronomy. This is expected to bring a revolution in our knowledge of the universe by allowing the observation of previously unseen phenomena, such as the coalescence of compact objects (neutron stars and black holes), the fall of stars into supermassive black holes, stellar core collapses, big-bang relics, and the new and unexpected.With a wide range of contributions by leading scientists in the field, Gravitational Waves covers topics such as the basics of GWs, various advanced topics, GW detectors, astrophysics of GW sources, numerical applications, and several recent theoretical developments. The material is written at a level suitable for postgraduate students entering the field.

  19. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter; Brorsen, Michael

    Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004.......Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004....

  20. Wave Propagation

    CERN Document Server

    Ferrarese, Giorgio

    2011-01-01

    Lectures: A. Jeffrey: Lectures on nonlinear wave propagation.- Y. Choquet-Bruhat: Ondes asymptotiques.- G. Boillat: Urti.- Seminars: D. Graffi: Sulla teoria dell'ottica non-lineare.- G. Grioli: Sulla propagazione del calore nei mezzi continui.- T. Manacorda: Onde nei solidi con vincoli interni.- T. Ruggeri: "Entropy principle" and main field for a non linear covariant system.- B. Straughan: Singular surfaces in dipolar materials and possible consequences for continuum mechanics

  1. Shock Waves

    CERN Document Server

    Jiang, Z

    2005-01-01

    The International Symposium on Shock Waves (ISSW) is a well established series of conferences held every two years in a different location. A unique feature of the ISSW is the emphasis on bridging the gap between physicists and engineers working in fields as different as gas dynamics, fluid mechanics and materials sciences. The main results presented at these meetings constitute valuable proceedings that offer anyone working in this field an authoritative and comprehensive source of reference.

  2. Gravitational waves from binary black holes

    Indian Academy of Sciences (India)

    It is almost a century since Einstein predicted the existence of gravitational waves as one of the consequences of his general theory of relativity. A brief historical overview including Chandrasekhar's contribution to the subject is first presented. The current status of the experimental search for gravitational waves and the ...

  3. Herbivore release through cascading risk effects.

    Science.gov (United States)

    Schmidt-Entling, Martin H; Siegenthaler, Eva

    2009-12-23

    Predators influence prey through consumption, and through trait-mediated effects such as emigration in response to predation risk (risk effects). We studied top-down effects of (sub-) adult wolf spiders (Lycosidae) on arthropods in a meadow. We compared risk effects with the overall top-down effect (including consumption) by gluing the chelicers of wolf spiders to prevent them from killing the prey. In a field experiment, we created three treatments that included either: (i) intact ('predation') wolf spiders; (ii) wolf spiders with glued chelicers ('risk spiders'); or (iii) no (sub-) adult wolf spiders. Young wolf spiders were reduced by their (sub-) adult congeners. Densities of sheetweb spiders (Linyphiidae), a known intraguild prey of wolf spiders, were equally reduced by the presence of risk and predation wolf spiders. Plant- and leafhoppers (Auchenorrhyncha) showed the inverse pattern of higher densities in the presence of both risk and predation wolf spiders. We conclude that (sub-) adult wolf spiders acted as top predators, which reduced densities of intermediate predators and thereby enhanced herbivores. Complementary to earlier studies that found trait-mediated herbivore suppression, our results demonstrate that herbivores can be enhanced through cascading risk effects by top predators.

  4. Particle energy cascade in the intergalactic medium

    Science.gov (United States)

    Valdés, M.; Evoli, C.; Ferrara, A.

    2010-05-01

    We study the development of high-energy (Ein new code MEDEA (Monte Carlo Energy Deposition Analysis) which includes Bremsstrahlung and inverse Compton (IC) processes, along with H/He collisional ionizations and excitations, and electron-electron collisions. The cascade energy partition into heating, excitations and ionizations depends primarily not only on the IGM ionized fraction, xe, but also on redshift, z, due to IC on cosmic microwave background (CMB) photons. While Bremsstrahlung is unimportant under most conditions, IC becomes largely dominant at energies Ein >= 1 MeV. The main effect of IC at injection energies Ein = 1 GeV CMB photons are preferentially upscattered within the X-ray spectrum (hν > 104 eV) and can free stream to the observer. Complete tables of the fractional energy depositions as a function of redshift, Ein and ionized fraction are given. Our results can be used in many astrophysical contexts, with an obvious application related to the study of decaying/annihilating dark matter (DM) candidates in the high-z Universe.

  5. Cascaded Amplitude Modulations in Sound Texture Perception

    Directory of Open Access Journals (Sweden)

    Richard McWalter

    2017-09-01

    Full Text Available Sound textures, such as crackling fire or chirping crickets, represent a broad class of sounds defined by their homogeneous temporal structure. It has been suggested that the perception of texture is mediated by time-averaged summary statistics measured from early auditory representations. In this study, we investigated the perception of sound textures that contain rhythmic structure, specifically second-order amplitude modulations that arise from the interaction of different modulation rates, previously described as “beating” in the envelope-frequency domain. We developed an auditory texture model that utilizes a cascade of modulation filterbanks that capture the structure of simple rhythmic patterns. The model was examined in a series of psychophysical listening experiments using synthetic sound textures—stimuli generated using time-averaged statistics measured from real-world textures. In a texture identification task, our results indicated that second-order amplitude modulation sensitivity enhanced recognition. Next, we examined the contribution of the second-order modulation analysis in a preference task, where the proposed auditory texture model was preferred over a range of model deviants that lacked second-order modulation rate sensitivity. Lastly, the discriminability of textures that included second-order amplitude modulations appeared to be perceived using a time-averaging process. Overall, our results demonstrate that the inclusion of second-order modulation analysis generates improvements in the perceived quality of synthetic textures compared to the first-order modulation analysis considered in previous approaches.

  6. Quantum cascade lasers (QCLs) in biomedical spectroscopy.

    Science.gov (United States)

    Schwaighofer, Andreas; Brandstetter, Markus; Lendl, Bernhard

    2017-10-02

    Quantum cascade lasers (QCL) are the first room temperature semiconductor laser source for the mid-IR spectral region, triggering substantial development for the advancement of mid-IR spectroscopy. Mid-IR spectroscopy in general provides rapid, label-free and objective analysis, particularly important in the field of biomedical analysis. Due to their unique properties, QCLs offer new possibilities for development of analytical methods to enable quantification of clinically relevant concentration levels and to support medical diagnostics. Compared to FTIR spectroscopy, novel and elaborated measurement techniques can be implemented that allow miniaturized and portable instrumentation. This review illustrates the characteristics of QCLs with a particular focus on their benefits for biomedical analysis. Recent applications of QCL-based spectroscopy for analysis of a variety of clinically relevant samples including breath, urine, blood, interstitial fluid, and biopsy samples are summarized. Further potential for technical advancements is discussed in combination with future prospects for employment of QCL-based devices in routine and point-of-care diagnostics.

  7. Cascading reminiscence bumps in popular music.

    Science.gov (United States)

    Krumhansl, Carol Lynne; Zupnick, Justin Adam

    2013-10-01

    Autobiographical memories are disproportionately recalled for events in late adolescence and early adulthood, a phenomenon called the reminiscence bump. Previous studies on music have found autobiographical memories and life-long preferences for music from this period. In the present study, we probed young adults' personal memories associated with top hits over 5-and-a-half decades, as well as the context of their memories and their recognition of, preference for, quality judgments of, and emotional reactions to that music. All these measures showed the typical increase for music released during the two decades of their lives. Unexpectedly, we found that the same measures peaked for the music of participants' parents' generation. This finding points to the impact of music in childhood and suggests that these results reflect the prevalence of music in the home environment. An earlier peak occurred for 1960s music, which may be explained by its quality or by its transmission through two generations. We refer to this pattern of musical cultural transmission over generations as cascading reminiscence bumps.

  8. Enhanced performance of quantum cascade Raman laser

    Science.gov (United States)

    Yousefvand, Hossein Reza; Aahmadi, Vahid

    2015-05-01

    We present a self-consistent numerical approach for quantum cascade Raman laser (QC-RL) with a modified design to improve the device performance. Our modeling approach is based on monolithic integration of stimulated Raman scattering (SRS) and electrically pumped QC laser. The laser band structure utilizing techniques with both material-dependent effective mass and band nonparabolicity is calculated by solving the Schrodinger-Poisson equations self-consistently. A detailed analysis of output characteristics of the obtained structure is carried out within a simplified 4-level rate equations model taking into account the SRS process. The model accurately explains the operating characteristics found in QCLs, such as damping transient response and non-resonant behavior of modulation frequency response. Furthermore, modification of the structure is focused on improving the SRS in the QC-RL. This leads to an enhancement of the device performance such as threshold current, external quantum efficiency, conversion efficiency, turn-on delay and modulation response. The excellent agreement of the experimental data with the simulated light output-current characteristics confirms the validity of the model.

  9. A screening cascade to identify ERβ ligands.

    Science.gov (United States)

    Filgueira, Carly S; Benod, Cindy; Lou, Xiaohua; Gunamalai, Prem S; Villagomez, Rosa A; Strom, Anders; Gustafsson, Jan-Åke; Berkenstam, Anders L; Webb, Paul

    2014-01-01

    The establishment of effective high throughput screening cascades to identify nuclear receptor (NR) ligands that will trigger defined, therapeutically useful sets of NR activities is of considerable importance. Repositioning of existing approved drugs with known side effect profiles can provide advantages because de novo drug design suffers from high developmental failure rates and undesirable side effects which have dramatically increased costs. Ligands that target estrogen receptor β (ERβ) could be useful in a variety of diseases ranging from cancer to neurological to cardiovascular disorders. In this context, it is important to minimize cross-reactivity with ERα, which has been shown to trigger increased rates of several types of cancer. Because of high sequence similarities between the ligand binding domains of ERα and ERβ, preferentially targeting one subtype can prove challenging. Here, we describe a sequential ligand screening approach comprised of complementary in-house assays to identify small molecules that are selective for ERβ. Methods include differential scanning fluorimetry, fluorescence polarization and a GAL4 transactivation assay. We used this strategy to screen several commercially-available chemical libraries, identifying thirty ERβ binders that were examined for their selectivity for ERβ versus ERα, and tested the effects of selected ligands in a prostate cancer cell proliferation assay. We suggest that this approach could be used to rapidly identify candidates for drug repurposing.

  10. New achromatic quarter-wave combination of birefringent plates

    Science.gov (United States)

    Saha, Arijit; Bhattacharya, Kallol; Chakraborty, Ajoy Kumar

    2012-01-01

    Phase retarders usually exhibit strong wavelength dependence. For this paper, the design and characteristics of an achromatic cascaded system of birefringent plates were studied. The combination of three retarders in a series had been previously proposed by Pancharatnam, and he discussed the possibility of fabricating reasonably good achromatic quarter-wave plates with a suitable level of retardance. This combination, however, still shows substantial variation in terms of retardance within 500 to 700 nm. Here, the combination of four plates for the construction of an almost achromatic quarter-wave plate, which has a variation of only +/- 1 degree over the wavelength spectrum of 500 to 700 nm, is proposed. Moreover, spherical trigonometric considerations have been used by Pancharatnam for obtaining the transmission characteristics of a cascaded system. We, however, used the succinct and relatively simple Jones matrix formalism to derive a general expression for the equivalent retardation of this combination. The proposed arrangement of four birefringent plates promises better achromatic combinations.

  11. Optimization of quantum cascade laser operation by geometric design of cascade active band in open and closed models

    Directory of Open Access Journals (Sweden)

    M.V. Tkach

    2013-01-01

    Full Text Available Using the effective mass and rectangular potential approximations, the theory of electron dynamic conductivity is developed for the plane multilayer resonance tunnel structure placed into a constant electric field within the model of open nanosystem, and oscillator forces of quantum transitions within the model of closed nanosystem. For the experimentally produced quantum cascade laser with four-barrier active band of separate cascade, it is proven that just the theory of dynamic conductivity in the model of open cascade most adequately describes the radiation of high frequency electromagnetic field while the electrons transport through the resonance tunnel structure driven by a constant electric field.

  12. Terahertz quantum-cascade lasers based on an interlaced photon-phonon cascade

    Science.gov (United States)

    Köhler, Rüdeger; Tredicucci, Alessandro; Mauro, Cosimo; Beltram, Fabio; Beere, Harvey E.; Linfield, Edmund H.; Davies, A. Giles; Ritchie, David A.

    2004-02-01

    A THz (λ˜80 μm) quantum-cascade laser utilizing alternating photon- and phonon-emitting stages has been developed to achieve efficient extraction of electrons from the lower laser level. Thermal backfilling of electrons is drastically reduced leading to an operation up to 95 K and a weak temperature dependence of the power versus current slope efficiency. The threshold current density is 280 A cm-2 at 6 K and increases to 580 A cm-2 at 90 K. Peak output powers of 10 mW at 30 K and 4 mW at 80 K are obtained.

  13. On periodic orbits in discrete-time cascade systems

    Directory of Open Access Journals (Sweden)

    Huimin Li

    2006-01-01

    Full Text Available We present some results on existence, minimum period, number of periodic orbits, and stability of periodic orbits in discrete-time cascade systems. Some examples are presented to illustrate these results.

  14. Quantum cascade laser infrared spectroscopy of single cancer cells

    KAUST Repository

    Patel, Imran

    2017-03-27

    Quantum cascade laser infrared spectroscopy is a next generation novel imaging technique allowing high resolution spectral imaging of cells. We show after spectral pre-processing, identification of different cancer cell populations within minutes.

  15. Critical Boundary of Cascaded Quadratic Soliton Compression in PPLN

    OpenAIRE

    Guo, Hairun; Zeng, Xianglong; Zhou, Binbin; Bache, Morten

    2012-01-01

    Cascaded quadratic soliton compression in PPLN is investigated and a general critical soliton number is found as the compression boundary. An optimal-parameter diagram for compression at 1550 nm is presented.

  16. Multicompartment Artificial Organelles Conducting Enzymatic Cascade Reactions inside Cells

    DEFF Research Database (Denmark)

    Gallardo, Maria Godoy; Labay, Cédric Pierre; Trikalitis, Vasileios

    2017-01-01

    capsosome system, which consists of multiple liposomes and fluorescent gold nanoclusters embedded within a polymer carrier capsule. We subsequently demonstrate that encapsulated enzymes preserve their activity intracellularly, allowing for controlled enzymatic cascade reaction within a host cell....

  17. Cascaded spintronic logic with low-dimensional carbon

    Science.gov (United States)

    Friedman, Joseph S.; Girdhar, Anuj; Gelfand, Ryan M.; Memik, Gokhan; Mohseni, Hooman; Taflove, Allen; Wessels, Bruce W.; Leburton, Jean-Pierre; Sahakian, Alan V.

    2017-06-01

    Remarkable breakthroughs have established the functionality of graphene and carbon nanotube transistors as replacements to silicon in conventional computing structures, and numerous spintronic logic gates have been presented. However, an efficient cascaded logic structure that exploits electron spin has not yet been demonstrated. In this work, we introduce and analyse a cascaded spintronic computing system composed solely of low-dimensional carbon materials. We propose a spintronic switch based on the recent discovery of negative magnetoresistance in graphene nanoribbons, and demonstrate its feasibility through tight-binding calculations of the band structure. Covalently connected carbon nanotubes create magnetic fields through graphene nanoribbons, cascading logic gates through incoherent spintronic switching. The exceptional material properties of carbon materials permit Terahertz operation and two orders of magnitude decrease in power-delay product compared to cutting-edge microprocessors. We hope to inspire the fabrication of these cascaded logic circuits to stimulate a transformative generation of energy-efficient computing.

  18. Mutually independent cascades in anisotropic soap-film turbulence

    Science.gov (United States)

    Liu, Chien-Chia; Gioia, Gustavo; Chakraborty, Pinaki

    2015-03-01

    Computational, experimental and field data amassed to date indicate that in 2D turbulence the spectrum of longitudinal velocity fluctuations, E11 (k1) , and the spectrum of transverse velocity fluctuations, E22 (k1) , correspond always to the same cascade, consistent with isotropy, so that E11 (k1) ~k-α and E22 (k1) ~k-α , where the ``spectral exponent'' α is either 5/3 (for the inverse-energy cascade) or 3 (for the enstrophy cascade). Here, we carry out experiments on turbulent 2D soap-film flows in which E11 (k1) ~k - 5 / 3 and E22 (k1) ~k-3 , as if two mutually independent cascades were concurrently active within the same flow. To our knowledge, this species of spectrum has never been observed or predicted theoretically. Our finding might open up new vistas in the understanding of turbulence.

  19. Cascade Structure of Digital Predistorter for Power Amplifier Linearization

    Directory of Open Access Journals (Sweden)

    E. B. Solovyeva

    2015-12-01

    Full Text Available In this paper, a cascade structure of nonlinear digital predistorter (DPD synthesized by the direct learning adaptive algorithm is represented. DPD is used for linearization of power amplifier (PA characteristic, namely for compensation of PA nonlinear distortion. Blocks of the cascade DPD are described by different models: the functional link artificial neural network (FLANN, the polynomial perceptron network (PPN and the radially pruned Volterra model (RPVM. At synthesis of the cascade DPD there is possibility to overcome the ill conditionality problem due to reducing the dimension of DPD nonlinear operator approximation. Results of compensating nonlinear distortion in Wiener–Hammerstein model of PA at the GSM–signal with four carriers are shown. The highest accuracy of PA linearization is produced by the cascade DPD containing PPN and RPVM.

  20. PULSE MODULATION POWER AMPLIFIER WITH ENHANCED CASCADE CONTROL METHOD

    DEFF Research Database (Denmark)

    1998-01-01

    A digital switching power amplifier with Multivariable Enhanced Cascade Controlled (MECC) includes a modulator, a switching power stage and a low pass filter. In the first preferred embodiment an enhanced cascade control structure local to the switching power stage is added, characterised by havi...... and feedback path A to determine stable self-oscillating conditions. An implemented 250W example MECC digital power amplifier has proven superior performance in terms of audio performance (0.005 % distortion, 115 dB dynamic range) and efficiency (92 %).......A digital switching power amplifier with Multivariable Enhanced Cascade Controlled (MECC) includes a modulator, a switching power stage and a low pass filter. In the first preferred embodiment an enhanced cascade control structure local to the switching power stage is added, characterised by having...

  1. The importance of sensory integration processes for action cascading

    OpenAIRE

    Krutika Gohil; Ann-Kathrin Stock; Christian Beste

    2015-01-01

    Dual tasking or action cascading is essential in everyday life and often investigated using tasks presenting stimuli in different sensory modalities. Findings obtained with multimodal tasks are often broadly generalized, but until today, it has remained unclear whether multimodal integration affects performance in action cascading or the underlying neurophysiology. To bridge this gap, we asked healthy young adults to complete a stop-change paradigm which presented different stimuli in either ...

  2. Noise properties and cascadability of SOA-EA regenerators

    DEFF Research Database (Denmark)

    Öhman, Filip; Bischoff, Svend; Tromborg, Bjarne

    2002-01-01

    We suggest and analyse a new device containing concatenated pairs of semiconductor optical amplifiers (SOAs) and electroabsorption modulators (EAs). The device has regenerative properties and improves the cascadability of optical fibre links.......We suggest and analyse a new device containing concatenated pairs of semiconductor optical amplifiers (SOAs) and electroabsorption modulators (EAs). The device has regenerative properties and improves the cascadability of optical fibre links....

  3. Climate Change and Baleen Whale Trophic Cascades in Greenland

    Science.gov (United States)

    2009-09-30

    DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. Climate Change and Baleen Whale Trophic Cascades in Greenland...SUBTITLE Climate Change And Baleen Whale Trophic Cascades In Greenland 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...2009. Polar bears in Northwest Greenland – An interview survey about the catch and the climate . Meddelelser om Grønland. [In Press, refereed] Heide

  4. Critical Boundary of Cascaded Quadratic Soliton Compression in PPLN

    DEFF Research Database (Denmark)

    Guo, Hairun; Zeng, Xianglong; Zhou, Binbin

    2012-01-01

    Cascaded quadratic soliton compression in PPLN is investigated and a general critical soliton number is found as the compression boundary. An optimal-parameter diagram for compression at 1550 nm is presented.......Cascaded quadratic soliton compression in PPLN is investigated and a general critical soliton number is found as the compression boundary. An optimal-parameter diagram for compression at 1550 nm is presented....

  5. Parton-hadron cascade approach at SPS and RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Nara, Yasushi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-07-01

    A parton-hadron cascade model which is the extension of hadronic cascade model incorporating hard partonic scattering based on HIJING is presented to describe the space-time evolution of parton/hadron system produced by ultra-relativistic nuclear collisions. Hadron yield, baryon stopping and transverse momentum distribution are calculated and compared with HIJING and VNI. Baryon density, energy density and temperature for RHIC are calculated within this model. (author)

  6. Advanced Dementia Research in the Nursing Home: The CASCADE Study

    OpenAIRE

    Mitchell, Susan L.; Kiely, Dan K.; Jones, Richard N.; Prigerson, Holly; Volicer, Ladislav; Teno, Joan M.

    2006-01-01

    Despite the growing number of persons with advanced dementia, and the need to improve their end-of-life care, few studies have addressed this important topic. The objectives of this report are to present the methodology established in the CASCADE (Choices, Attitudes, and Strategies for Care of Advanced Dementia at the End-of-Life) study, and to describe how challenges specific to this research were met. The CASCADE study is an ongoing, federally funded, 5-year prospective cohort study of nurs...

  7. REFLECTION OF ELECTROMAGNETIC WAVES FROM SOUND WAVES

    Science.gov (United States)

    The reflection of electromagnetic waves normally incident on the wavefronts of a semi-infinite standing sound wave is discussed. By analogy with the...with the sound frequency. An experiment is described in which the Bragg reflection of 3 cm electromagnetic waves from a standing sound wave beneath a water surface is observed.

  8. Impact of Wave Dragon on Wave Climate

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Tedd, James; Kramer, Morten

    This report is an advisory paper for use in determining the wave dragon effects on hydrography, by considering the effect on the wave climate in the region of a wave dragon. This is to be used in the impact assessment for the Wave Dragon pre-commercial demonstrator....

  9. Drift waves in the turbulence of reversed field pinch plasmas

    Science.gov (United States)

    Thuecks, Derek

    2017-10-01

    Turbulence is one of the principal mediators of energy exchange in natural and laboratory plasma settings, for example wave-particle interactions that lead to collisionless heating and acceleration. The turbulent cascade carried by Alfvenic fluctuations is especially important in magnetized plasmas, operating on a wide range of scales larger than the ion gyroradius. The MST laboratory plasma exhibits a robust turbulent cascade driven by tearing instability, which is likely connected to powerful non-collisional ion heating that is also observed. New electric and magnetic field fluctuation measurements in the plasma edge reveal a broadband cascade that is anisotropic relative to the mean B0. Magnetic fluctuations dominate at the tearing scale, as expected, but energy equipartition is not observed at smaller scales. Instead, the kinetic energy, 1/2 mini (Ẽ ×B0)2 , begins to dominate at kperpρi > 0.2 . Statistical coherency between density, parallel magnetic field, and floating potential fluctuations reveals previously unobserved features at this energy-crossing scale that are consistent with electron-branch drift waves with a phase velocity comparable to the electron drift speed. The edge region contains a strong density gradient, and either drift-Alfven coupling or unstable modes could be responsible for the excess kinetic energy. The turbulent energy rises and falls in concert with the tearing mode amplitudes, which suggests nonlinear wave coupling powers the cascade, but the coherency at small scales is more persistent than at the tearing-scale during sawtooth relaxation cycles, which suggests possible independent drift wave instability. Gradient regions are a universal feature of plasma interfaces, and similarities may be exploited to better understand turbulent dynamics in other space and laboratory plasmas, e.g., the corona-wind interface. Supported by DOE and NSF.

  10. Diurnal changes of photosynthesis and growth of Arthrospira platensis cultured in a thin-layer cascade and an open pond

    Czech Academy of Sciences Publication Activity Database

    Benavides, A.M.S.; Ranglová, Karolína; Malapascua, José R.; Masojídek, Jiří; Torzillo, G.

    2017-01-01

    Roč. 28, DEC (2017), s. 48-56 ISSN 2211-9264 R&D Projects: GA MŠk(CZ) LO1416; GA MŠk EE2.3.30.0059 Grant - others:AV ČR(CZ) CNR-16-29 Program:Bilaterální spolupráce Institutional support: RVO:61388971 Keywords : Arthrospira platensis * Pond * Thin-layer cascade Subject RIV: EE - Microbiology, Virology Impact factor: 3.994, year: 2016

  11. Power system cascading risk assessment based on complex network theory

    Science.gov (United States)

    Wang, Zhuoyang; Hill, David J.; Chen, Guo; Dong, Zhao Yang

    2017-09-01

    When a single failure occurs in a vulnerable part of a power system, this may cause a large area cascading event. Therefore, an advanced method that can assess the risks during cascading events is needed. In this paper, an improved complex network model for power system risk assessment is proposed. Risk is defined by consequence and probability of the failures in this model, which are affected by both power factors and network structure. Compared with existing risk assessment models, the proposed one can evaluate the risk of the system comprehensively during a cascading event by combining the topological and electrical information. A new cascading event simulation module is adopted to identify the power grid cascading chain from a system-level view. In addition, simulations are investigated on the IEEE 14 bus system and IEEE 39 bus system respectively to illustrate the performance of the proposed module. The simulation results demonstrate that the proposed method is effective in a power grid risk assessment during cascading event.

  12. Signal transduction in a covalent post-assembly modification cascade

    Science.gov (United States)

    Pilgrim, Ben S.; Roberts, Derrick A.; Lohr, Thorsten G.; Ronson, Tanya K.; Nitschke, Jonathan R.

    2017-12-01

    Natural reaction cascades control the movement of biomolecules between cellular compartments. Inspired by these systems, we report a synthetic reaction cascade employing post-assembly modification reactions to direct the partitioning of supramolecular complexes between phases. The system is composed of a self-assembled tetrazine-edged FeII8L12 cube and a maleimide-functionalized FeII4L6 tetrahedron. Norbornadiene (NBD) functions as the stimulus that triggers the cascade, beginning with the inverse-electron-demand Diels-Alder reaction of NBD with the tetrazine moieties of the cube. This reaction generates cyclopentadiene as a transient by-product, acting as a relay signal that subsequently undergoes a Diels-Alder reaction with the maleimide-functionalized tetrahedron. Cyclooctyne can selectively inhibit the cascade by outcompeting NBD as the initial trigger. Initiating the cascade with 2-octadecyl NBD leads to selective alkylation of the tetrahedron upon cascade completion. The increased lipophilicity of the C18-tagged tetrahedron drives this complex into a non-polar phase, allowing its isolation from the initially inseparable mixture of complexes.

  13. Cascading off Davis Strait as seen from a NEMO simulation

    Science.gov (United States)

    Marson, Juliana M.; Myers, Paul G.; Hu, Xianmin; Petrie, Brian; Azetsu-Scott, Kumiko; Lee, Craig

    2017-04-01

    Cascading occurs when dense waters form and accumulate on the continental shelf, eventually sliding down the slope and reaching intermediate and deep layers of the ocean. It is an important process for ventilating the deep ocean and capturing carbon from the atmosphere. Although observed in several different locations, especially at high latitudes, cascading has never been reported for the western Greenland shelf. We use the results from a 2002-2014 NEMO ocean model simulation to show that cascading could happen sporadically at Davis Strait. Over the time span of the model run, cascading occurred during five winters with each event starting around February and persisting until the end of May. The occurrence of those events seems to be dependent on (1) the balance between sea ice formation and melting in the region; (2) the amount of freshwater coming from the Arctic through Fram Strait; (3) the presence of West Greenland Irminger Water on the shelf. The cascading water primarily flows into deep Baffin Bay, although not at a sufficient rate to be a primary source of Baffin Bay Deep Water. The simulation's temperature and salinity interannual variability in Davis Strait agrees reasonably with observations (CTD profiles and moorings) but overestimates the peak salinity and density and consequently the strength of the cascade process. Nonetheless, the model simulation indicates that this phenomenon has the potential to occur in this location.

  14. Cascading failures in spatially-embedded random networks.

    Science.gov (United States)

    Asztalos, Andrea; Sreenivasan, Sameet; Szymanski, Boleslaw K; Korniss, Gyorgy

    2014-01-01

    Cascading failures constitute an important vulnerability of interconnected systems. Here we focus on the study of such failures on networks in which the connectivity of nodes is constrained by geographical distance. Specifically, we use random geometric graphs as representative examples of such spatial networks, and study the properties of cascading failures on them in the presence of distributed flow. The key finding of this study is that the process of cascading failures is non-self-averaging on spatial networks, and thus, aggregate inferences made from analyzing an ensemble of such networks lead to incorrect conclusions when applied to a single network, no matter how large the network is. We demonstrate that this lack of self-averaging disappears with the introduction of a small fraction of long-range links into the network. We simulate the well studied preemptive node removal strategy for cascade mitigation and show that it is largely ineffective in the case of spatial networks. We introduce an altruistic strategy designed to limit the loss of network nodes in the event of a cascade triggering failure and show that it performs better than the preemptive strategy. Finally, we consider a real-world spatial network viz. a European power transmission network and validate that our findings from the study of random geometric graphs are also borne out by simulations of cascading failures on the empirical network.

  15. Mitigate Cascading Failures on Networks using a Memetic Algorithm.

    Science.gov (United States)

    Tang, Xianglong; Liu, Jing; Hao, Xingxing

    2016-12-09

    Research concerning cascading failures in complex networks has become a hot topic. However, most of the existing studies have focused on modelling the cascading phenomenon on networks and analysing network robustness from a theoretical point of view, which considers only the damage incurred by the failure of one or several nodes. However, such a theoretical approach may not be useful in practical situation. Thus, we first design a much more practical measure to evaluate the robustness of networks against cascading failures, termed Rcf. Then, adopting Rcf as the objective function, we propose a new memetic algorithm (MA) named MA-Rcf to enhance network the robustness against cascading failures. Moreover, we design a new local search operator that considers the characteristics of cascading failures and operates by connecting nodes with a high probability of having similar loads. In experiments, both synthetic scale-free networks and real-world networks are used to test the efficiency and effectiveness of the MA-Rcf. We systematically investigate the effects of parameters on the performance of the MA-Rcf and validate the performance of the newly designed local search operator. The results show that the local search operator is effective, that MA-Rcf can enhance network robustness against cascading failures efficiently, and that it outperforms existing algorithms.

  16. Implementation of a quantum cascade laser-based gas sensor prototype for sub-ppmv H2S measurements in a petrochemical process gas stream

    OpenAIRE

    Moser, Harald; P?lz, Walter; Waclawek, Johannes Paul; Ofner, Johannes; Lendl, Bernhard

    2016-01-01

    The implementation of a sensitive and selective as well as industrial fit gas sensor prototype based on wavelength modulation spectroscopy with second harmonic detection (2f-WMS) employing an 8-?m continuous-wave distributed feedback quantum cascade laser (CW-DFB-QCL) for monitoring hydrogen sulfide (H2S) at sub-ppm levels is reported. Regarding the applicability for analytical and industrial process purposes aimed at petrochemical environments, a synthetic methane (CH4) matrix of up to 1000?...

  17. Simulation model of harmonics reduction technique using shunt active filter by cascade multilevel inverter method

    Science.gov (United States)

    Andreh, Angga Muhamad; Subiyanto, Sunardiyo, Said

    2017-01-01

    Development of non-linear loading in the application of industry and distribution system and also harmonic compensation becomes important. Harmonic pollution is an urgent problem in increasing power quality. The main contribution of the study is the modeling approach used to design a shunt active filter and the application of the cascade multilevel inverter topology to improve the power quality of electrical energy. In this study, shunt active filter was aimed to eliminate dominant harmonic component by injecting opposite currents with the harmonic component system. The active filter was designed by shunt configuration with cascaded multilevel inverter method controlled by PID controller and SPWM. With this shunt active filter, the harmonic current can be reduced so that the current wave pattern of the source is approximately sinusoidal. Design and simulation were conducted by using Power Simulator (PSIM) software. Shunt active filter performance experiment was conducted on the IEEE four bus test system. The result of shunt active filter installation on the system (IEEE four bus) could reduce THD current from 28.68% to 3.09%. With this result, the active filter can be applied as an effective method to reduce harmonics.

  18. Freedom from band-gap slavery: from diode lasers to quantum cascade lasers

    Science.gov (United States)

    Capasso, Federico

    2010-02-01

    Semiconductor heterostructure lasers, for which Alferov and Kromer received part of the Nobel Prize in Physics in 2000, are the workhorse of technologies such as optical communications, optical recording, supermarket scanners, laser printers and fax machines. They exhibit high performance in the visible and near infrared and rely for their operation on electrons and holes emitting photons across the semiconductor bandgap. This mechanism turns into a curse at longer wavelengths (mid-infrared) because as the bandgap, shrinks laser operation becomes much more sensitive to temperature, material defects and processing. Quantum Cascade Laser (QCL), invented in 1994, rely on a radically different process for light emission. QCLs are unipolar devices in which electrons undergo transitions between quantum well energy levels and are recycled through many stages emitting a cascade of photons. Thus by suitable tailoring of the layers' thickness, using the same heterostructure material, they can lase across the molecular fingerprint region from 3 to 25 microns and beyond into the far-infrared and submillimiter wave spectrum. High power cw room temperature QCLs and QCLs with large continuous single mode tuning range have found many applications (infrared countermeasures, spectroscopy, trace gas analysis and atmospheric chemistry) and are commercially available. )

  19. Characterisation of the Rota Wewa tank cascade system in the vicinity of Anuradhapura, Sri Lanka

    Directory of Open Access Journals (Sweden)

    Schütt, Brigitta

    2013-09-01

    Full Text Available A complex and sustainable watershed management strategy was implemented in Sri Lanka during the ancient Anuradhapura period, from the 5th century BC to the 11th century AD. Like modern watershed management strategies, it focused on flood prevention, soil erosion control, water quality control and water storage for irrigation. Tank cascade systems were the key element of these ancient watershed management installations. The wewas investigated were constructed in valleys characterised by fluvial accumulation. Sedimentological analyses of these tank cascade systems show that a precise age determination and the reconstruction of sediment and water f luxes as triggered by human-environment interactions are difficult. This is caused by the shallow character of the wewas leading to the steady redeposition of the tank sediments by wave motions during the wet season and agricultural use of the desiccated wewas during the dry season. Beyond, the sediments analysed allow to distinguish between the weathered parent bedrock and the overlying sediments. A differentiation between wewa deposits and the underlying fluvial deposits remains challenging.

  20. Cooperative behavior cascades in human social networks

    National Research Council Canada - National Science Library

    James H. Fowler; Nicholas A. Christakis; Daniel Kahneman

    2010-01-01

    .... Observational data suggest that a wide variety of behaviors may spread in human social networks, but subjects in such studies can choose to befriend people with similar behaviors, posing difficulty for causal inference...

  1. Human initiated cascading failures in societal infrastructures.

    Directory of Open Access Journals (Sweden)

    Chris Barrett

    Full Text Available In this paper, we conduct a systematic study of human-initiated cascading failures in three critical inter-dependent societal infrastructures due to behavioral adaptations in response to a crisis. We focus on three closely coupled socio-technical networks here: (i cellular and mesh networks, (ii transportation networks and (iii mobile call networks. In crises, changes in individual behaviors lead to altered travel, activity and calling patterns, which influence the transport network and the loads on wireless networks. The interaction between these systems and their co-evolution poses significant technical challenges for representing and reasoning about these systems. In contrast to system dynamics models for studying these interacting infrastructures, we develop interaction-based models in which individuals and infrastructure elements are represented in detail and are placed in a common geographic coordinate system. Using the detailed representation, we study the impact of a chemical plume that has been released in a densely populated urban region. Authorities order evacuation of the affected area, and this leads to individual behavioral adaptation wherein individuals drop their scheduled activities and drive to home or pre-specified evacuation shelters as appropriate. They also revise their calling behavior to communicate and coordinate among family members. These two behavioral adaptations cause flash-congestion in the urban transport network and the wireless network. The problem is exacerbated with a few, already occurring, road closures. We analyze how extended periods of unanticipated road congestion can result in failure of infrastructures, starting with the servicing base stations in the congested area. A sensitivity analysis on the compliance rate of evacuees shows non-intuitive effect on the spatial distribution of people and on the loading of the base stations. For example, an evacuation compliance rate of 70% results in higher number

  2. Product lifecycle approach to cascade impaction measurements.

    Science.gov (United States)

    Tougas, Terrence P; Christopher, Dave; Mitchell, Jolyon; Lyapustina, Svetlana; Van Oort, Michiel; Bauer, Richard; Glaab, Volker

    2011-03-01

    Over the lifecycle of an orally inhaled product (OIP), multi-stage cascade impactor (CI) measurements are used for different purposes and to address different questions. Full-resolution CIs can provide important information during product development and are widely used but are time- and resource-intensive, highly variable, and suboptimal for OIP quality control (QC) testing. By contrast, Efficient Data Analysis (EDA) combined with Abbreviated Impactor Measurement (AIM) systems pertinent either for QC and-possibly-for adult Human Respiratory Tract (pHRT) has been introduced for OIP performance assessment during and post-development. This article summarizes available evidence and discusses a strategy for using either abbreviated or full-resolution CI systems depending on the purpose of the measurement, such that adequate, accurate, and efficient testing of aerodynamic particle size distribution (APSD) of OIPs can be achieved throughout the lifecycle of a product. Under these proposals, a comprehensive testing program should initially be conducted by full-resolution CI in OIP development to ascertain the product's APSD. Subsequently, correlations should be established from the selected AIM CIs to the corresponding full-resolution system, ideally developing specifications common to both techniques. In the commercial phase, it should be possible to release product using AIM/EDA, keeping the full-resolution CI for investigations, change control, and trouble-shooting, thus optimizing resources for APSD characterization throughout the product lifecycle. If an in vitro-in vivo relationship is established and clinically relevant sizes are known, an AIM-pHRT could serve as a quick indicator that clinically relevant fractions have not changed and also, in the management of post-approval changes. © 2011 American Association of Pharmaceutical Scientists

  3. Cascaded processing in written compound word production

    Directory of Open Access Journals (Sweden)

    Raymond eBertram

    2015-04-01

    Full Text Available In this study we investigated the intricate interplay between central linguistic processing and peripheral motor processes during typewriting. Participants had to typewrite two-constituent (noun-noun Finnish compounds in response to picture presentation while their typing behavior was registered. As dependent measures we used writing onset time to assess what processes were completed before writing and inter-key intervals to assess what processes were going on during writing. It was found that writing onset time was determined by whole word frequency rather than constituent frequencies, indicating that compound words are retrieved as whole orthographic units before writing is initiated. In addition, we found that the length of the first syllable also affects writing onset time, indicating that the first syllable is fully prepared before writing commences. The inter-key interval results showed that linguistic planning is not fully ready before writing, but cascades into the motor execution phase. More specifically, inter-key intervals were largest at syllable and morpheme boundaries, supporting the view that additional linguistic planning takes place at these boundaries. Bigram and trigram frequency also affected inter-key intervals with shorter intervals corresponding to higher frequencies. This can be explained by stronger memory traces for frequently co-occurring letter sequences in the motor memory for typewriting. These frequency effects were even larger in the second than in the first constituent, indicating that low-level motor memory starts to become more important during the course of writing compound words. We discuss our results in the light of current models of morphological processing and written word production.

  4. Longitudinal gradients along a reservoir cascade

    Science.gov (United States)

    Miranda, L.E.; Habrat, M.D.; Miyazono, S.

    2008-01-01

    Reservoirs have traditionally been regarded as spatially independent entities rather than as longitudinal segments of a river system that are connected upstream and downstream to the river and other reservoirs. This view has frustrated advancement in reservoir science by impeding adequate organization of available information and by hindering interchanges with allied disciplines that often consider impounded rivers at the basin scale. We analyzed reservoir morphology, water quality, and fish assemblage data collected in 24 reservoirs of the Tennessee River; we wanted to describe longitudinal changes occurring at the scale of the entire reservoir series (i.e., cascade) and to test the hypothesis that fish communities and environmental factors display predictable gradients like those recognized for unimpounded rivers. We used a data set collected over a 7-year period; over 3 million fish representing 94 species were included in the data set. Characteristics such as reservoir mean depth, relative size of the limnetic zone, water retention time, oxygen stratification, thermal stratification, substrate size, and water level fluctuations increased in upstream reservoirs. Conversely, reservoir area, extent of riverine and littoral zones, access to floodplains and associated wetlands, habitat diversity, and nutrient and sediment inputs increased in downstream reservoirs. Upstream reservoirs included few, largely lacustrine, ubiquitous fish taxa that were characteristic of the lentic upper reaches of the basin. Fish species richness increased in a downstream direction from 12 to 67 species/ reservoir as riverine species became more common. Considering impoundments at a basin scale by viewing them as sections in a river or links in a chain may generate insight that is not always available when the impoundments are viewed as isolated entities. Basin-scale variables are rarely controllable but constrain the expression of processes at smaller scales and can facilitate the

  5. Effect of polarization on the performance of ZnO/MgZnO quantum cascade detector

    Science.gov (United States)

    Li, Zhaoling; Wang, Ping; He, Jingfang; Chen, Hongyan; Cheng, Jingsi

    2017-11-01

    The impact of polarization effect on the performance of ZnO/MgZnO quantum cascade detector (QCD) is investigated with different scattering mechanisms taken into account. The energy band structure and wave functions are achieved by self-consistent calculation of Schrodinger-Poisson equations considering the spontaneous and piezoelectric polarization effects. The polarization field in the well or barrier of the QCD is obtained by assuming continuity of the displacement vector and the electronic transport is determined by piezoelectric polarization induced piezoelectric scattering, LO-phonon scattering and some other scattering mechanisms. The results show that the polarization charges at the interface make a significant contribution to the confining potential, which reduces the dark current, and increases the detectivity. The peak responsivity drops only 6.37% from 57 to 400 K without apparent redshift and the detectivity can be significantly improved by increasing doping concentration. This work is beneficial for the ZnO/MgZnO QCD design.

  6. Concept for power scaling second harmonic generation using a cascade of nonlinear crystals

    DEFF Research Database (Denmark)

    Hansen, Anders Kragh; Tawfieq, Mahmoud; Jensen, Ole Bjarlin

    2015-01-01

    Within the field of high-power second harmonic generation (SHG), power scaling is often hindered by adverse crystal effects such as thermal dephasing arising from the second harmonic (SH) light, which imposes limits on the power that can be generated in many crystals. Here we demonstrate a concept...... for efficient power scaling of single-pass SHG beyond such limits using a cascade of nonlinear crystals, in which the first crystal is chosen for high nonlinear efficiency and the subsequent crystal(s) are chosen for power handling ability. Using this highly efficient singlepass concept, we generate 3.7 W...... of continuous-wave diffraction-limited 2 ( 1.25) M = light at 532 nm from 9.5 W of non-diffraction-limited 2 ( 7.7) M = light from a tapered laser diode, while avoiding significant thermal effects. Besides constituting the highest SH power yet achieved using a laser diode, this demonstrates that the concept...

  7. Full potential solution of a transonic quasi-3-D flow through a cascade using artificial compressibility

    Science.gov (United States)

    Farrell, C.; Adamczyk, J.

    1981-01-01

    A reliable method is presented for calculating the flowfield about a cascade of arbitrary 2-D airfoils. The method approximates the three-dimensional flow in a turbomachinery blade row by correcting for streamtube convergence and radius change in the throughflow direction. The method is a fully conservative solution of the full potential equation incorporating the finite volume technique on a body-fitted periodic mesh, with an artificial density imposed in the transonic region to ensure stability and the capture of shock waves. Comparison of results for several supercritical blades shows good agreement with their hodograph solutions. Other calculations for these profiles as well as standard NACA blade sections indicate that this is a useful scheme for analyzing both the design and off-design performance of turbomachinery blading.

  8. Ultrasonic sensor employing two cascaded phase-shifted fiber Bragg gratings suitable for multiplexing.

    Science.gov (United States)

    Wu, Qi; Okabe, Yoji

    2012-08-15

    An ultrasonic sensor based on two cascaded phase-shifted fiber Bragg gratings (PS-FBGs) is proposed and demonstrated. In place of an external cavity laser, a broadband amplified spontaneous emission light source is used to demonstrate multiplexing ability suitable for sensor networks. The system has a high sensitivity to ultrasonic waves generated by a PZT actuator placed 7.5 cm away from the PS-FBG, because of the steep slope in the center of the PS-FBG spectrum. A second advantage of the phase shift is to reduce the effective sensor length, leading to the achievement of broadband characteristics. A pencil lead break test was performed and all results are compared to a traditional PZT sensor.

  9. Extended and quasi-continuous tuning of quantum cascade lasers using superstructure gratings and integrated heaters

    Energy Technology Data Exchange (ETDEWEB)

    Bidaux, Yves, E-mail: yves.bidaux@alpeslasers.ch [Alpes Lasers SA, 1-3 Passsage Max Meuron, CH-2001 Neuchâtel (Switzerland); Institute for Quantum Electronics, ETH-Zurich, CH-8093 Zurich (Switzerland); Bismuto, Alfredo, E-mail: alfredo.bismuto@alpeslasers.ch; Tardy, Camille; Terazzi, Romain; Gresch, Tobias; Blaser, Stéphane; Muller, Antoine [Alpes Lasers SA, 1-3 Passsage Max Meuron, CH-2001 Neuchâtel (Switzerland); Faist, Jerome [Institute for Quantum Electronics, ETH-Zurich, CH-8093 Zurich (Switzerland)

    2015-11-30

    In this work, we demonstrate broad electrical tuning of quantum cascade lasers at 9.25 μm, 8.5 μm, and 4.4 μm in continuous wave operation using Vernier-effect distributed Bragg reflectors based on superstructure gratings. Integrated micro-heaters allow to switch from one Vernier channel to the other, while predictable and mode-hop free tuning can be obtained in each channel modulating the laser current with a side mode suppression ratio as high as 30 dB. The resulting device behaves effectively as a switchable multicolour tunable source. Tuning up to 6.5% of the central wavelength is observed. To prove the importance of the developed devices for high resolution molecular spectroscopy, a N{sub 2}O absorption spectrum has been measured.

  10. QEPAS nitric oxide sensor based on a mid-infrared fiber-coupled quantum cascade laser

    Science.gov (United States)

    Ren, Wei; Shi, Chao; Wang, Zhen; Yao, Chenyu

    2017-04-01

    We report a quartz-enhanced photoacoustic sensor (QEPAS) for nitric oxide (NO) detection using a mid-infrared fibercoupled quantum cascade laser (QCL) near 5.2 μm. The QCL radiation was coupled into an InF3 fiber (100 μm core diameter) for light delivery to the quartz tuning fork, a tiny piezoelectric element converting the acoustic wave induced mechanical vibration to the gas-absorption associated electrical signal. This mid-infrared fiber can achieve nearly single-mode light delivery for the target wavelength. The off-beam configuration was adopted for the fiber-coupled detection considering its simpler installation, optical alignment and comparative sensitivity to the traditional on-beam setup.

  11. First Results of PIC Modeling of Kinetic Alfven Wave Dissipation

    Science.gov (United States)

    Chulaki, Anna; Hesse, Michael; Zenitani, Seiji

    2007-01-01

    We present first results of an investigation of the kinetic damping of Alfven wave turbulence. The methodology is based on a fully electromagnetic, three-dimensional, particle in cell code. The calculation is initialized by an Alfven wave spectrum. Subsequently, a cascade develops, and damping by coupling to both ions and electrons is observed. We discuss results of these calculations, and present first estimates of damping rates and of the effects of energy transfer on ion and electron distributions. The results pertain to solar wind heating and acceleration.

  12. P Wave Ananysis In Asymptomatic Healthy Adult Nigerian Students ...

    African Journals Online (AJOL)

    The P wave amplitude and duration were measured and analyzed in the 12-lead ECG in a hundred and nine subjects aged between 19 and 30 years. The mean P wave duration was 0.07 ± 0.02 sec. Significant correlation was found between P wave duration and amplitude and various anthropometric measurements.

  13. INTERFERENCE OF COUNTERPROPAGATING SHOCK WAVES

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2015-03-01

    Full Text Available The subject of study. We examined the interaction of counterpropagating shock waves. The necessity of counterpropagating shock waves studying occurs at designing of high Mach number modern internal compression air intakes, Ramjets with subsonic and supersonic combustion, in asymmetrical supersonic nozzles and in some other cases. In a sense, this problem is a generalization of the case of an oblique shock reflection from the wall or from the plane of symmetry. With the renewed vigor, the interest to this problem emerged at the end of the 90s. This was due to the start of the programs for flight study at hypersonic speeds. The first experiments performed with air intakes, which realized the interaction of counterpropagating shock waves have shown that the change in flow velocity is accompanied by abrupt alteration of shock-wave structure, the occurrence of nonstationary and oscillatory phenomena. With an increase of flow velocity these phenomena undesirable for aircraft structure became more marked. The reason is that there are two fundamentally different modes of interaction of counterpropagating shock waves: a four-wave regular and a five-wave irregular. The transition from one mode to another can be nonstationary abrupt or gradual, it can also be accompanied by hysteresis. Main results. Criteria for the transition from regular reflection of counterpropagating shock waves to irregular are described: the criterion of von Neumann and the stationary Mach configuration criterion. We described areas in which the transition from one reflection type to another is possible only in abrupt way, as well as areas of possible gradual transition. Intensity dependences of the reflected shock waves from the intensity of interacting counterpropagating shocks were given. Qualitative pictures of shock-wave structures arising from the interaction of counterpropagating shock waves were shown. Calculation results of the intensity of outgoing gas

  14. Efficient Wave Energy Amplification with Wave Reflectors

    DEFF Research Database (Denmark)

    Kramer, Morten Mejlhede; Frigaard, Peter Bak

    2002-01-01

    Wave Energy Converters (WEC's) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased to approximately 130......-140%. In the paper a procedure for calculating the efficiency and optimizing the geometry of wave reflectors are described, this by use of a 3D boundary element method. The calculations are verified by laboratory experiments and a very good agreement is found. The paper gives estimates of possible power benifit...... for different geometries of the wave reflectors and optimal geometrical design parameters are specified. On this basis inventors of WEC's can evaluate whether a specific WEC possible could benefit from wave reflectors....

  15. General relativity and gravitational waves

    CERN Document Server

    Weber, Johanna

    1961-01-01

    An internationally famous physicist and electrical engineer, the author of this text was a pioneer in the investigation of gravitational waves. Joseph Weber's General Relativity and Gravitational Waves offers a classic treatment of the subject. Appropriate for upper-level undergraduates and graduate students, this text remains ever relevant. Brief but thorough in its introduction to the foundations of general relativity, it also examines the elements of Riemannian geometry and tensor calculus applicable to this field.Approximately a quarter of the contents explores theoretical and experimenta

  16. Introduction to vibrations and waves

    CERN Document Server

    Pain, H John

    2015-01-01

    Based on the successful multi-edition book "The Physics ofVibrations and Waves" by John Pain, the authors carry overthe simplicity and logic of the approach taken in the originalfirst edition with its focus on the patterns underlying andconnecting so many aspects of physical behavior, whilst bringingthe subject up-to-date so it is relevant to teaching in the21st century.The transmission of energy by wave propagation is a key conceptthat has applications in almost every branch of physics withtransmitting mediums essentially acting as a continuum of coupledoscillators. The characterization of t

  17. Cascading effects of interparental conflict in adolescence: Linking threat appraisals, self-efficacy, and adjustment.

    Science.gov (United States)

    Fosco, Gregory M; Feinberg, Mark E

    2015-02-01

    This study examined the longitudinal implications of adolescents' exposure to interparental conflict for their developmental success. In the proposed developmental cascade model, adolescents' perceptions of parental conflict as threatening is a risk factor for diminished self-efficacy, which would account for diminished adjustment. This study presents longitudinal data for 768 sixth-grade students and their families over four time points, ending in eighth grade. Analyses were conducted in three steps. First, replication of longitudinal support for threat as a mediator of the link between interparental conflict and emotional distress was found; however, findings did not support threat as a mediator of behavior problems or subjective well-being. Second, threat was found to mediate the longitudinal association between interparental conflict and self-efficacy. Third, a developmental cascade model supported a risk process in which interparental conflict was related to adolescents' threat appraisals, which undermined self-efficacy beliefs, and was then linked with emotional distress, behavior problems, and subjective well-being.

  18. Contribution of non-resonant wave-wave interactions in the dynamics of long-crested sea wave fields

    Science.gov (United States)

    Benoit, Michel

    2017-04-01

    Gravity waves fields at the surface of the oceans evolve under the combined effects of several physical mechanisms, of which nonlinear wave-wave interactions play a dominant role. These interactions transfer energy between components within the energy spectrum and allow in particular to explain the shape of the distribution of wave energy according to the frequencies and directions of propagation. In the oceanic domain (deep water conditions), dominant interactions are third-order resonant interactions, between quadruplets (or quartets) of wave components, and the evolution of the wave spectrum is governed by a kinetic equation, established by Hasselmann (1962) and Zakharov (1968). The kinetic equation has a number of interesting properties, including the existence of self-similar solutions and cascades to small and large wavelengths of waves, which can be studied in the framework of the wave (or weak) turbulence theory (e.g. Badulin et al., 2005). With the aim to obtain more complete and precise modelling of sea states dynamics, we investigate here the possibility and consequences of taking into account the non-resonant interactions -quasi-resonant in practice- among 4 waves. A mathematical formalism has recently been proposed to account for these non-resonant interactions in a statistical framework by Annenkov & Shrira (2006) (Generalized Kinetic Equation, GKE) and Gramstad & Stiassnie (2013) (Phase Averaged Equation, PAE). In order to isolate the non-resonant contributions, we limit ourselves here to monodirectional (i.e. long-crested) wave trains, since in this case the 4-wave resonant interactions vanish. The (stochastic) modelling approaches proposed by Annenkov & Shrira (2006) and Gramstad & Stiassnie (2013) are compared to phase-resolving (deterministic) simulations based on a fully nonlinear potential approach (using a high-order spectral method, HOS). We study and compare the evolution dynamics of the wave spectrum at different time scales (i.e. over

  19. Three stage cascade diode lasers generating 500 mW near 3.2 μm

    Energy Technology Data Exchange (ETDEWEB)

    Hosoda, Takashi; Wang, Meng; Shterengas, Leon, E-mail: leon.shterengas@stonybrook.edu; Kipshidze, Gela; Belenky, Gregory [State University of New York at Stony Brook, Stony Brook, New York 11794 (United States)

    2015-09-14

    GaSb-based type-I quantum well 3.1–3.2 μm diode lasers with two- and three-cascade heterostructures were designed, fabricated, and characterized. Devices with ∼100-μm-wide aperture, 3-mm-long cavity, and anti-/high-reflection coated mirrors demonstrated continuous wave output power of 500 mW, threshold current density of ∼200 A/cm{sup 2}, and peak power conversion efficiency of ∼7% at 17 °C. This corresponds to more than twofold improvement in terms of output power and efficiency as compared to standard diode lasers operating in the same spectral region. The experiment showed that the increase in the number of cascades from two to three led to critical enhancement of the differential gain and reduction of the threshold current density. Light p-doping of the AlGaAsSb graded section did not introduce extra optical loss but aided hole transport as required for realization of the efficient multi-stage cascade pumping scheme.

  20. Three stage cascade diode lasers generating 500 mW near 3.2 μm

    Science.gov (United States)

    Hosoda, Takashi; Wang, Meng; Shterengas, Leon; Kipshidze, Gela; Belenky, Gregory

    2015-09-01

    GaSb-based type-I quantum well 3.1-3.2 μm diode lasers with two- and three-cascade heterostructures were designed, fabricated, and characterized. Devices with ˜100-μm-wide aperture, 3-mm-long cavity, and anti-/high-reflection coated mirrors demonstrated continuous wave output power of 500 mW, threshold current density of ˜200 A/cm2, and peak power conversion efficiency of ˜7% at 17 °C. This corresponds to more than twofold improvement in terms of output power and efficiency as compared to standard diode lasers operating in the same spectral region. The experiment showed that the increase in the number of cascades from two to three led to critical enhancement of the differential gain and reduction of the threshold current density. Light p-doping of the AlGaAsSb graded section did not introduce extra optical loss but aided hole transport as required for realization of the efficient multi-stage cascade pumping scheme.

  1. Aeration efficiency over stepped cascades: better predictions from flow regimes.

    Science.gov (United States)

    Khdhiri, Hatem; Potier, Olivier; Leclerc, Jean-Pierre

    2014-05-15

    Stepped cascades are recognized as high potential air-water gas exchangers. In natural rivers, these structures enhance oxygen transfer to water by creating turbulence at interface with increasing air entrainment in water and air-water surface exchange. Stepped cascades could be really useful to improve the natural self-purification process by providing oxygen to aerobic micro-organisms. The aeration performance of these structures depends on several operating and geometrical parameters. In the literature, several empirical correlations for aeration efficiency prediction on stepped cascades exist. Most of these correlations are only applicable for operating and geometrical parameters in the range of which they have been developed. In this paper, 398 experimental sets of data (from our experiments and collected from literature) were used to develop a correlation for aeration prediction over stepped cascades derived from dimensional analysis and parameterized for each individual flow regime in order to consider change in flow regime effect on oxygen transfer. This new correlation allowed calculating the whole set of data obtained for cascades with steps heights between 0.05 m and 0.254 m, cascade total height between 0.25 m and 2.5 m, for discharges per unit of width ranging from 0.28 10(-3) m(2)/s to 600 10(-3) m(2)/s and for cascade steps number between 3 and 25. In these ranges of parameters, standard deviation for aeration efficiency estimation was found to be less than 17%. Finally, advices were proposed to help and improve the structure design in order to improve aeration. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Millimeter-wave antennas configurations and applications

    CERN Document Server

    du Preez, Jaco

    2016-01-01

    This book comprehensively reviews the state of the art in millimeter-wave antennas, traces important recent developments and provides information on a wide range of antenna configurations and applications. While fundamental theoretical aspects are discussed whenever necessary, the book primarily focuses on design principles and concepts, manufacture, measurement techniques, and practical results. Each of the various antenna types scalable to millimeter-wave dimensions is considered individually, with coverage of leaky-wave and surface-wave antennas, printed antennas, integrated antennas, and reflector and lens systems. The final two chapters address the subject from a systems perspective, providing an overview of supporting circuitry and examining in detail diverse millimeter-wave applications, including high-speed wireless communications, radio astronomy, and radar. The vast amount of information now available on millimeter-wave systems can be daunting for researchers and designers entering the field. This b...

  3. Cascaded systems analysis of photon counting detectors.

    Science.gov (United States)

    Xu, J; Zbijewski, W; Gang, G; Stayman, J W; Taguchi, K; Lundqvist, M; Fredenberg, E; Carrino, J A; Siewerdsen, J H

    2014-10-01

    Photon counting detectors (PCDs) are an emerging technology with applications in spectral and low-dose radiographic and tomographic imaging. This paper develops an analytical model of PCD imaging performance, including the system gain, modulation transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). A cascaded systems analysis model describing the propagation of quanta through the imaging chain was developed. The model was validated in comparison to the physical performance of a silicon-strip PCD implemented on an experimental imaging bench. The signal response, MTF, and NPS were measured and compared to theory as a function of exposure conditions (70 kVp, 1-7 mA), detector threshold, and readout mode (i.e., the option for coincidence detection). The model sheds new light on the dependence of spatial resolution, charge sharing, and additive noise effects on threshold selection and was used to investigate the factors governing PCD performance, including the fundamental advantages and limitations of PCDs in comparison to energy-integrating detectors (EIDs) in the linear regime for which pulse pileup can be ignored. The detector exhibited highly linear mean signal response across the system operating range and agreed well with theoretical prediction, as did the system MTF and NPS. The DQE analyzed as a function of kilovolt (peak), exposure, detector threshold, and readout mode revealed important considerations for system optimization. The model also demonstrated the important implications of false counts from both additive electronic noise and charge sharing and highlighted the system design and operational parameters that most affect detector performance in the presence of such factors: for example, increasing the detector threshold from 0 to 100 (arbitrary units of pulse height threshold roughly equivalent to 0.5 and 6 keV energy threshold, respectively), increased the f50 (spatial-frequency at which the MTF falls to a value of

  4. The HIV care cascade: Japanese perspectives.

    Directory of Open Access Journals (Sweden)

    Aikichi Iwamoto

    Full Text Available Japan has been known as a low HIV-prevalence country with a concentrated epidemic among high-risk groups. However, it has not been determined whether Japan meets the 90-90-90 goals set by the Joint United Nations Programme on HIV/AIDS (UNAIDS/World Health Organization (WHO. Moreover, to date, the HIV care cascade has not been examined. We estimated the total number of diagnosed people living with HIV/AIDS (PLWHA (n = 22,840 based on legal reports to the Ministry of Health, Labour and Welfare by subtracting the number of foreigners who left Japan (n = 2,273 and deaths (n = 2,321 from the cumulative diagnosis report (n = 27,434. The number of total undiagnosed PLWHA was estimated by age and sex specific HIV-positive rates observed among first-time blood donors between 2011-2015 in Japan. Our estimates show that 14.4% (n = 3,830 of all PLWHA (n = 26,670 were undiagnosed in Japan at the end of 2015. The number of patients retained in care (n = 20,615: 77.3% of PLWHA, the percentage of those on antiretroviral therapy (n = 18,921: 70.9% of PLWHA and those with suppressed viral loads (<200 copies/mL; n = 18,756: 70.3% of PLWHA were obtained through a questionnaire survey conducted in the AIDS Core Hospitals throughout the country. According to these estimates, Japan failed to achieve the first two of the three UNAIDS/WHO targets (22,840/26,670 = 85.6% of HIV-positive cases were diagnosed; 18,921/22,840 = 82.8% of those diagnosed were treated; 18,756/18,921 = 99.1% of those treated experienced viral suppression. Although the antiretroviral treatment uptake and success after retention in medical care appears to be excellent in Japan, there are unmet needs, mainly at the surveillance level before patients are retained in care. The promotion of HIV testing and treatment programs among the key affected populations (especially men who have sex with men may contribute to further decreasing the HIV epidemic and achieving the UNAIDS/WHO targets in Japan.

  5. Cascades and Dissipative Anomalies in Compressible Fluid Turbulence

    Science.gov (United States)

    Eyink, Gregory L.; Drivas, Theodore D.

    2018-02-01

    We investigate dissipative anomalies in a turbulent fluid governed by the compressible Navier-Stokes equation. We follow an exact approach pioneered by Onsager, which we explain as a nonperturbative application of the principle of renormalization-group invariance. In the limit of high Reynolds and Péclet numbers, the flow realizations are found to be described as distributional or "coarse-grained" solutions of the compressible Euler equations, with standard conservation laws broken by turbulent anomalies. The anomalous dissipation of kinetic energy is shown to be due not only to local cascade but also to a distinct mechanism called pressure-work defect. Irreversible heating in stationary, planar shocks with an ideal-gas equation of state exemplifies the second mechanism. Entropy conservation anomalies are also found to occur via two mechanisms: an anomalous input of negative entropy (negentropy) by pressure work and a cascade of negentropy to small scales. We derive "4 /5 th-law"-type expressions for the anomalies, which allow us to characterize the singularities (structure-function scaling exponents) required to sustain the cascades. We compare our approach with alternative theories and empirical evidence. It is argued that the "Big Power Law in the Sky" observed in electron density scintillations in the interstellar medium is a manifestation of a forward negentropy cascade or an inverse cascade of usual thermodynamic entropy.

  6. Trend-driven information cascades on random networks.

    Science.gov (United States)

    Kobayashi, Teruyoshi

    2015-12-01

    Threshold models of global cascades have been extensively used to model real-world collective behavior, such as the contagious spread of fads and the adoption of new technologies. A common property of those cascade models is that a vanishingly small seed fraction can spread to a finite fraction of an infinitely large network through local infections. In social and economic networks, however, individuals' behavior is often influenced not only by what their direct neighbors are doing, but also by what the majority of people are doing as a trend. A trend affects individuals' behavior while individuals' behavior creates a trend. To analyze such a complex interplay between local- and global-scale phenomena, I generalize the standard threshold model by introducing a type of node called global nodes (or trend followers), whose activation probability depends on a global-scale trend, specifically the percentage of activated nodes in the population. The model shows that global nodes play a role as accelerating cascades once a trend emerges while reducing the probability of a trend emerging. Global nodes thus either facilitate or inhibit cascades, suggesting that a moderate share of trend followers may maximize the average size of cascades.

  7. Gradients in Catostomid assemblages along a reservoir cascade

    Science.gov (United States)

    Miranda, Leandro E.; Keretz, Kevin R.; Gilliland, Chelsea R.

    2017-01-01

    Serial impoundment of major rivers leads to alterations of natural flow dynamics and disrupts longitudinal connectivity. Catostomid fishes (suckers, family Catostomidae) are typically found in riverine or backwater habitats yet are able to persist in impounded river systems. To the detriment of conservation, there is limited information about distribution of catostomid fishes in impounded rivers. We examined the longitudinal distribution of catostomid fishes over 23 reservoirs of the Tennessee River reservoir cascade, encompassing approximately 1600 km. Our goal was to develop a basin-scale perspective to guide conservation efforts. Catostomid species composition and assemblage structure changed longitudinally along the reservoir cascade. Catostomid species biodiversity was greatest in reservoirs lower in the cascade. Assemblage composition shifted from dominance by spotted sucker Minytrema melanops and buffalos Ictiobus spp. in the lower reservoirs to carpsuckers Carpiodes spp. midway through the cascade and redhorses Moxostoma spp. in the upper reservoirs. Most species did not extend the length of the cascade, and some species were rare, found in low numbers and in few reservoirs. The observed gradients in catostomid assemblages suggest the need for basin-scale conservation measures focusing on three broad areas: (1) conservation and management of the up-lake riverine reaches of the lower reservoirs, (2) maintenance of the access to quality habitat in tributaries to the upper reservoirs and (3) reintroductions into currently unoccupied habitat within species' historic distributions

  8. INCAS: an analytical model to describe displacement cascades

    Science.gov (United States)

    Jumel, Stéphanie; Claude Van-Duysen, Jean

    2004-07-01

    REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricité de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory.

  9. INCAS: an analytical model to describe displacement cascades

    Energy Technology Data Exchange (ETDEWEB)

    Jumel, Stephanie E-mail: stephanie.jumel@edf.fr; Claude Van-Duysen, Jean E-mail: jean-claude.van-duysen@edf.fr

    2004-07-01

    REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricite de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory.

  10. Reducing Cascading Failure Risk by Increasing Infrastructure Network Interdependence

    Science.gov (United States)

    Korkali, Mert; Veneman, Jason G.; Tivnan, Brian F.; Bagrow, James P.; Hines, Paul D. H.

    2017-01-01

    Increased interconnection between critical infrastructure networks, such as electric power and communications systems, has important implications for infrastructure reliability and security. Others have shown that increased coupling between networks that are vulnerable to internetwork cascading failures can increase vulnerability. However, the mechanisms of cascading in these models differ from those in real systems and such models disregard new functions enabled by coupling, such as intelligent control during a cascade. This paper compares the robustness of simple topological network models to models that more accurately reflect the dynamics of cascading in a particular case of coupled infrastructures. First, we compare a topological contagion model to a power grid model. Second, we compare a percolation model of internetwork cascading to three models of interdependent power-communication systems. In both comparisons, the more detailed models suggest substantially different conclusions, relative to the simpler topological models. In all but the most extreme case, our model of a “smart” power network coupled to a communication system suggests that increased power-communication coupling decreases vulnerability, in contrast to the percolation model. Together, these results suggest that robustness can be enhanced by interconnecting networks with complementary capabilities if modes of internetwork failure propagation are constrained. PMID:28317835

  11. The physics of waves

    CERN Document Server

    Georgi, Howard

    1993-01-01

    The first complete introduction to waves and wave phenomena by a renowned theorist. Covers damping, forced oscillations and resonance; normal modes; symmetries; traveling waves; signals and Fourier analysis; polarization; diffraction.

  12. Sensibility and Subjectivity: Levinas’ Traumatic Subject

    Directory of Open Access Journals (Sweden)

    Rashmika Pandya

    2011-02-01

    Full Text Available The importance of Levinas’ notions of sensibility and subjectivity are evident in the revision of phenomenological method by current phenomenologists such as Jean-Luc Marion and Michel Henry. The criticisms of key tenants of classical phenomenology, intentionality and reduction, are of a particular note. However, there are problems with Levinas’ characterization of subjectivity as essentially sensible. In “Totality and Infinity” and “Otherwise than Being”, Levinas criticizes and recasts a traditional notion of subjectivity, particularly the notion of the subject as the first and foremost rational subject. The subject in Levinas’ works is characterized more by its sensibility and affectedness than by its capacity to reason or affect its world. Levinas ties rationality to economy and suggests an alternative notion of reason that leads to his analysis of the ethical relation as the face-to-face encounter. The ‘origin’ of the social relation is located not in our capacity to know but rather in a sensibility that is diametrically opposed to the reason understood as economy. I argue that the opposition in Levinas’ thought between reason and sensibility is problematic and essentially leads to a self-conflicted subject. In fact, it would seem that violence characterizes the subject’s self-relation and, thus, is also inscribed at the base of the social relation. Rather than overcoming a problematic tendency to dualistic thought in philosophy Levinas merely reverses traditional hierarchies of reason/emotion, subject/object and self/other. 

  13. Cascaded VLSI Chips Help Neural Network To Learn

    Science.gov (United States)

    Duong, Tuan A.; Daud, Taher; Thakoor, Anilkumar P.

    1993-01-01

    Cascading provides 12-bit resolution needed for learning. Using conventional silicon chip fabrication technology of VLSI, fully connected architecture consisting of 32 wide-range, variable gain, sigmoidal neurons along one diagonal and 7-bit resolution, electrically programmable, synaptic 32 x 31 weight matrix implemented on neuron-synapse chip. To increase weight nominally from 7 to 13 bits, synapses on chip individually cascaded with respective synapses on another 32 x 32 matrix chip with 7-bit resolution synapses only (without neurons). Cascade correlation algorithm varies number of layers effectively connected into network; adds hidden layers one at a time during learning process in such way as to optimize overall number of neurons and complexity and configuration of network.

  14. A Cascade-Based Emergency Model for Water Distribution Network

    Directory of Open Access Journals (Sweden)

    Qing Shuang

    2015-01-01

    Full Text Available Water distribution network is important in the critical physical infrastructure systems. The paper studies the emergency resource strategies on water distribution network with the approach of complex network and cascading failures. The model of cascade-based emergency for water distribution network is built. The cascade-based model considers the network topology analysis and hydraulic analysis to provide a more realistic result. A load redistribution function with emergency recovery mechanisms is established. From the aspects of uniform distribution, node betweenness, and node pressure, six recovery strategies are given to reflect the network topology and the failure information, respectively. The recovery strategies are evaluated with the complex network indicators to describe the failure scale and failure velocity. The proposed method is applied by an illustrative example. The results showed that the recovery strategy considering the node pressure can enhance the network robustness effectively. Besides, this strategy can reduce the failure nodes and generate the least failure nodes per time.

  15. Bearing-Only Formation Control for Cascade Multirobots

    Directory of Open Access Journals (Sweden)

    Qing Han

    2016-01-01

    Full Text Available A new formation control method is proposed, which is used to queue multirobots in a single-direction cascade structure. In the cascade formation, each robot is a follower for the previous robot and a leader for the next robot, and the robots in the middle act as both leader and follower. The follower robot can only observe the bearing information of the leader robot. The observability of the cascade leader-follower formation is studied, which shows that the bearing-only observation meets the observability conditions required for the nonlinear system. Based on the bearing-only observations, the unscented Kalman filter (UKF is employed for the state estimation of the leader and the follower robots at all levels, which enables the real-time movement control of the follower robots via the input-output feedback control. Simulation results demonstrate that the proposed approach can efficiently control the formation of multirobots as desired.

  16. Performance validation of a cascade control system through

    Directory of Open Access Journals (Sweden)

    A. Lakshmi Sangeetha

    2016-11-01

    Full Text Available The work analyzes the performance characteristics of a cascade control system when interconnected with various network architectures, such as Internet, mobile and wireless networks. The cascade control system consists of level and flow as primary and secondary variables, respectively. The web-enabled monitoring and control are realized using three techniques namely remote client–server, ActiveX-data socket and web publishing tool. Mobile network is established by interfacing the control system with a GSM modem which enables the monitoring of process parameters through mobile phones. The cascade control system is also monitored wirelessly from remote locations with advent of an indigenous wireless sensor node. The performance analysis proved that wireless monitoring may be considered as an effective alternate technique to the Internet-based communication especially for shorter distances.

  17. The Alzheimer's Disease Mitochondrial Cascade Hypothesis: Progress and Perspectives

    Science.gov (United States)

    Swerdlow, Russell H.; Burns, Jeffrey M.; Khan, Shaharyar M.

    2013-01-01

    Ten years ago we first proposed the Alzheimer's disease (AD) mitochondrial cascade hypothesis. This hypothesis maintains gene inheritance defines an individual's baseline mitochondrial function; inherited and environmental factors determine rates at which mitochondrial function changes over time; and baseline mitochondrial function and mitochondrial change rates influence AD chronology. Our hypothesis unequivocally states in sporadic, late-onset AD, mitochondrial function affects amyloid precursor protein (APP) expression, APP processing, or beta amyloid (Aβ) accumulation and argues if an amyloid cascade truly exists, mitochondrial function triggers it. We now review the state of the mitochondrial cascade hypothesis, and discuss it in the context of recent AD biomarker studies, diagnostic criteria, and clinical trials. Our hypothesis predicts biomarker changes reflect brain aging, new AD definitions clinically stage brain aging, and removing brain Aβ at any point will marginally impact cognitive trajectories. Our hypothesis, therefore, offers unique perspective into what sporadic, late-onset AD is and how to best treat it. PMID:24071439

  18. The Alzheimer's disease mitochondrial cascade hypothesis: progress and perspectives.

    Science.gov (United States)

    Swerdlow, Russell H; Burns, Jeffrey M; Khan, Shaharyar M

    2014-08-01

    Ten years ago we first proposed the Alzheimer's disease (AD) mitochondrial cascade hypothesis. This hypothesis maintains that gene inheritance defines an individual's baseline mitochondrial function; inherited and environmental factors determine rates at which mitochondrial function changes over time; and baseline mitochondrial function and mitochondrial change rates influence AD chronology. Our hypothesis unequivocally states in sporadic, late-onset AD, mitochondrial function affects amyloid precursor protein (APP) expression, APP processing, or beta amyloid (Aβ) accumulation and argues if an amyloid cascade truly exists, mitochondrial function triggers it. We now review the state of the mitochondrial cascade hypothesis, and discuss it in the context of recent AD biomarker studies, diagnostic criteria, and clinical trials. Our hypothesis predicts that biomarker changes reflect brain aging, new AD definitions clinically stage brain aging, and removing brain Aβ at any point will marginally impact cognitive trajectories. Our hypothesis, therefore, offers unique perspective into what sporadic, late-onset AD is and how to best treat it. © 2013.

  19. Substrate-driven chemotactic assembly in an enzyme cascade

    Science.gov (United States)

    Zhao, Xi; Palacci, Henri; Yadav, Vinita; Spiering, Michelle M.; Gilson, Michael K.; Butler, Peter J.; Hess, Henry; Benkovic, Stephen J.; Sen, Ayusman

    2018-03-01

    Enzymatic catalysis is essential to cell survival. In many instances, enzymes that participate in reaction cascades have been shown to assemble into metabolons in response to the presence of the substrate for the first enzyme. However, what triggers metabolon formation has remained an open question. Through a combination of theory and experiments, we show that enzymes in a cascade can assemble via chemotaxis. We apply microfluidic and fluorescent spectroscopy techniques to study the coordinated movement of the first four enzymes of the glycolysis cascade: hexokinase, phosphoglucose isomerase, phosphofructokinase and aldolase. We show that each enzyme independently follows its own specific substrate gradient, which in turn is produced by the preceding enzymatic reaction. Furthermore, we find that the chemotactic assembly of enzymes occurs even under cytosolic crowding conditions.

  20. Cascading Failures in Networks: Inference, Intervention and Robustness to WMDs

    Science.gov (United States)

    2016-08-01

    8725 John J. Kingman Road, MS 6201 Fort Belvoir, VA 22060-6201 T E C H N IC A L R E P O R T DTRA-TR-16-83 Cascading Failures in Networks...Austin   Project  Title:  Cascading   Failures  in  Networks:  Inference,  Intervention  and  Robustness  to   WMDs   What  are  the  major  goals  of...networks  are  prone  to  creating  cascading   failures :  events  where  the   initial  destruction/compromising  of  a  few  nodes  results  in  the

  1. High-Efficiency and High-Power Mid-Wave Infrared Cascade Lasers

    Science.gov (United States)

    2012-10-01

    Ω is the Rabi frequency associated with the optical field and is defined as (in the unit of energy) Ω...offset δU in Eq. (3.1). For QC lasers with design wavelength >8μm, lattice - matched In0.53Ga0.47As/Al0.48In0.52As on InP is used; for QC lasers with

  2. Special Issue ;Sediment cascades in cold climate geosystems;

    Science.gov (United States)

    Morche, David; Krautblatter, Michael; Beylich, Achim A.

    2017-06-01

    This Editorial introduces the Special Issue on sediment cascades in cold climate geosystems that evolved from the eighth I.A.G./A.I.G. SEDIBUD (Sediment Budgets in Cold Environments; http://www.geomorph.org/sedibud-working-group/) workshop. The workshop was held from 1st to 4th September 2014 at the Environmental Research Station ;Schneefernerhaus; (http://www.schneefernerhaus.de/en/home.html) located at Mt. Zugspitze, the highest peak of Germany, (2962 m asl). Paper and poster presentations focused on observations, measurements and modeling of geomorphological processes in sediment cascades in cold climate geosystems. This resulting Special Issue brings together ten selected contributions from arctic and alpine environments.

  3. Cascade Control of Magnetic Levitation with Sliding Modes

    Directory of Open Access Journals (Sweden)

    Eroğlu Yakup

    2016-01-01

    Full Text Available The effectiveness and applicability of magnetic levitation systems need precise feedback control designs. A cascade control approach consisting of sliding mode control plus sliding mode control (SMC plus SMC is designed to solve position control problem and to provide a high control performance and robustness to the magnetic levitation plant. It is shown that the SMC plus SMC cascade controller is able to eliminate the effects of the inductance related uncertainties of the electromagnetic coil of the plant and achieve a robust and precise position control. Experimental and numerical results are provided to validate the effectiveness and feasibility of the method.

  4. Process Evaluation Tools for Enzymatic Cascades Welcome Message

    DEFF Research Database (Denmark)

    Abu, Rohana

    limited reactions are not only via application of enzyme coupling reactions (coupling the unfavourable reaction with an energetically favourable reaction) but also by matching the relative reaction rates between the interconnecting enzymes. When the reaction steps are independent in a cascade......, the kinetics can be controlled in a highly efficient way to achieve a sufficiently favourable conversion to a given target product. This is exemplified in the second case study, in the kinetic modelling of the formation of 2-ketoglutarate from glucoronate, the second case study. This cascade consists of 4...

  5. Limits to compression with cascaded quadratic soliton compressors

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw

    2008-01-01

    We study cascaded quadratic soliton compressors and address the physical mechanisms that limit the compression. A nonlocal model is derived, and the nonlocal response is shown to have an additional oscillatory component in the nonstationary regime when the group-velocity mismatch (GVM) is strong....... This inhibits efficient compression. Raman-like perturbations from the cascaded nonlinearity, competing cubic nonlinearities, higher-order dispersion, and soliton energy may also limit compression, and through realistic numerical simulations we point out when each factor becomes important. We find...

  6. Fast perceptual image hash based on cascade algorithm

    Science.gov (United States)

    Ruchay, Alexey; Kober, Vitaly; Yavtushenko, Evgeniya

    2017-09-01

    In this paper, we propose a perceptual image hash algorithm based on cascade algorithm, which can be applied in image authentication, retrieval, and indexing. Image perceptual hash uses for image retrieval in sense of human perception against distortions caused by compression, noise, common signal processing and geometrical modifications. The main disadvantage of perceptual hash is high time expenses. In the proposed cascade algorithm of image retrieval initializes with short hashes, and then a full hash is applied to the processed results. Computer simulation results show that the proposed hash algorithm yields a good performance in terms of robustness, discriminability, and time expenses.

  7. Spectral energy transfer of atmospheric gravity waves through sum and difference nonlinear interactions

    Directory of Open Access Journals (Sweden)

    K. M. Huang

    2012-02-01

    Full Text Available Nonlinear interactions of gravity waves are studied with a two-dimensional, fully nonlinear model. The energy exchanges among resonant and near-resonant triads are examined in order to understand the spectral energy transfer through interactions. The results show that in both resonant and near-resonant interactions, the energy exchange between two high frequency waves is strong, but the energy transfer from large to small vertical scale waves is rather weak. This suggests that the energy cascade toward large vertical wavenumbers through nonlinear interaction is inefficient, which is different from the rapid turbulence cascade. Because of considerable energy exchange, nonlinear interactions can effectively spread high frequency spectrum, and play a significant role in limiting wave amplitude growth and transferring energy into higher altitudes. In resonant interaction, the interacting waves obey the resonant matching conditions, and resonant excitation is reversible, while near-resonant excitation is not so. Although near-resonant interaction shows the complexity of match relation, numerical experiments show an interesting result that when sum and difference near-resonant interactions occur between high and low frequency waves, the wave vectors tend to approximately match in horizontal direction, and the frequency of the excited waves is also close to the matching value.

  8. Cascading elastic perturbation in Japan due to the 2012 Mw 8.6 Indian Ocean earthquake

    Science.gov (United States)

    Delorey, Andrew A.; Chao, Kevin; Obara, Kazushige; Johnson, Paul A.

    2015-01-01

    Since the discovery of extensive earthquake triggering occurring in response to the 1992 Mw (moment magnitude) 7.3 Landers earthquake, it is now well established that seismic waves from earthquakes can trigger other earthquakes, tremor, slow slip, and pore pressure changes. Our contention is that earthquake triggering is one manifestation of a more widespread elastic disturbance that reveals information about Earth’s stress state. Earth’s stress state is central to our understanding of both natural and anthropogenic-induced crustal processes. We show that seismic waves from distant earthquakes may perturb stresses and frictional properties on faults and elastic moduli of the crust in cascading fashion. Transient dynamic stresses place crustal material into a metastable state during which the material recovers through a process termed slow dynamics. This observation of widespread, dynamically induced elastic perturbation, including systematic migration of offshore seismicity, strain transients, and velocity transients, presents a new characterization of Earth’s elastic system that will advance our understanding of plate tectonics, seismicity, and seismic hazards. PMID:26601289

  9. Ion Bernstein wave heating research

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Masayuki.

    1992-03-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW's low phase velocity ({omega}/k{sub {perpendicular}} {approx} V{sub Ti} {much lt} V{sub {alpha}}) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion {alpha}-particles. In addition, the property of IBW's that k{sub {perpendicular}} {rho}{sub i} {approx} 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW's can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research.

  10. Ion Bernstein wave heating research

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Masayuki

    1992-03-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW`s low phase velocity ({omega}/k{sub {perpendicular}} {approx} V{sub Ti} {much_lt} V{sub {alpha}}) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion {alpha}-particles. In addition, the property of IBW`s that k{sub {perpendicular}} {rho}{sub i} {approx} 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW`s can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research.

  11. Interrelation of structure and operational states in cascading failure of overloading lines in power grids

    Science.gov (United States)

    Xue, Fei; Bompard, Ettore; Huang, Tao; Jiang, Lin; Lu, Shaofeng; Zhu, Huaiying

    2017-09-01

    As the modern power system is expected to develop to a more intelligent and efficient version, i.e. the smart grid, or to be the central backbone of energy internet for free energy interactions, security concerns related to cascading failures have been raised with consideration of catastrophic results. The researches of topological analysis based on complex networks have made great contributions in revealing structural vulnerabilities of power grids including cascading failure analysis. However, existing literature with inappropriate assumptions in modeling still cannot distinguish the effects between the structure and operational state to give meaningful guidance for system operation. This paper is to reveal the interrelation between network structure and operational states in cascading failure and give quantitative evaluation by integrating both perspectives. For structure analysis, cascading paths will be identified by extended betweenness and quantitatively described by cascading drop and cascading gradient. Furthermore, the operational state for cascading paths will be described by loading level. Then, the risk of cascading failure along a specific cascading path can be quantitatively evaluated considering these two factors. The maximum cascading gradient of all possible cascading paths can be used as an overall metric to evaluate the entire power grid for its features related to cascading failure. The proposed method is tested and verified on IEEE30-bus system and IEEE118-bus system, simulation evidences presented in this paper suggests that the proposed model can identify the structural causes for cascading failure and is promising to give meaningful guidance for the protection of system operation in the future.

  12. Waves in metamaterials

    CERN Document Server

    Solymar, Laszlo

    2014-01-01

    Metamaterials is a young subject born in the 21st century. It is concerned with artificial materials which can have electrical and magnetic properties difficult or impossible to find in nature. The building blocks in most cases are resonant elements much smaller than the wavelength of the electromagnetic wave. The book offers a comprehensive treatment of all aspects of research in this field at a level that should appeal to final year undergraduates in physics or in electrical and electronic engineering. The mathematics is kept at a minimum; the aim is to explain the physics in simple terms and enumerate the major advances. It can be profitably read by graduate and post-graduate students in order to find out what has been done in the field outside their speciality, and by experts who may gain new insight about the inter-relationship of the physical phenomena involved.

  13. ELECTRON CYCLOTRON WAVES

    NARCIS (Netherlands)

    Westerhof, E.

    2010-01-01

    This lecture gives an overview of heating and current drive with electron cyclotron waves. We present the main theoretical aspects of wave propagation, wave absorption, and non-inductive current drive, as well as important technical aspects for the application of high power electron cyclotron waves,

  14. Electron cyclotron waves

    NARCIS (Netherlands)

    Westerhof, E.

    2012-01-01

    This lecture gives an overview of heating and current drive with electron cyclotron waves. We present the main theoretical aspects of wave propagation, wave absorption, and non-inductive current drive, as well as important technical aspects for the application of high power electron cyclotron waves,

  15. Electron cyclotron waves

    NARCIS (Netherlands)

    Westerhof, E.

    2008-01-01

    This lecture gives an overview of heating and current drive with electron cyclotron waves. We present the main theoretical aspects of wave propagation, wave absorption, and non-inductive current drive, as well as important technical aspects for the application of high power electron cyclotron waves,

  16. Waves in inhomogeneous media

    NARCIS (Netherlands)

    Gerritsen, S.

    2007-01-01

    In this thesis we study wave propagation in inhomogeneous media. Examples of the classical (massless) waves we consider are acoustic waves (sound) and electromagnetic waves (light, for example). Interaction with inhomogeneities embedded in a reference medium alter the propagation direction, velocity

  17. Thai Finger-Spelling Recognition Using a Cascaded Classifier Based on Histogram of Orientation Gradient Features

    Directory of Open Access Journals (Sweden)

    Kittasil Silanon

    2017-01-01

    Full Text Available Hand posture recognition is an essential module in applications such as human-computer interaction (HCI, games, and sign language systems, in which performance and robustness are the primary requirements. In this paper, we proposed automatic classification to recognize 21 hand postures that represent letters in Thai finger-spelling based on Histogram of Orientation Gradient (HOG feature (which is applied with more focus on the information within certain region of the image rather than each single pixel and Adaptive Boost (i.e., AdaBoost learning technique to select the best weak classifier and to construct a strong classifier that consists of several weak classifiers to be cascaded in detection architecture. We collected 21 static hand posture images from 10 subjects for testing and training in Thai letters finger-spelling. The parameters for the training process have been adjusted in three experiments, false positive rates (FPR, true positive rates (TPR, and number of training stages (N, to achieve the most suitable training model for each hand posture. All cascaded classifiers are loaded into the system simultaneously to classify different hand postures. A correlation coefficient is computed to distinguish the hand postures that are similar. The system achieves approximately 78% accuracy on average on all classifier experiments.

  18. Wave Data Analysis

    DEFF Research Database (Denmark)

    Alikhani, Amir; Frigaard, Peter; Burcharth, Hans F.

    1998-01-01

    The data collected over the course of the experiment must be analysed and converted into a form suitable for its intended use. Type of analyses range from simple to sophisticated. Depending on the particular experiment and the needs of the researcher. In this study three main part of irregular wave...... data analyses are presented e.g. Time Domain (Statistical) Analyses, Frequency Domain (Spectral) Analyses and Wave Reflection Analyses. Random wave profile and definitions of representative waves, distributions of individual wave height and wave periods and spectra of sea waves are presented....

  19. Cascade Screening in Families with Inherited Cardiac Diseases Driven by Cardiologists

    DEFF Research Database (Denmark)

    Theilade, Juliane; Kanters, Jørgen; Henriksen, Finn Lund

    2013-01-01

    We assessed the outcome of cascade screening of families with congenital long QT syndrome (LQTS) in Danish heart centers.......We assessed the outcome of cascade screening of families with congenital long QT syndrome (LQTS) in Danish heart centers....

  20. Cascading Constrained 2-D Arrays using Periodic Merging Arrays

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Laursen, Torben Vaarby

    2003-01-01

    We consider a method for designing 2-D constrained codes by cascading finite width arrays using predefined finite width periodic merging arrays. This provides a constructive lower bound on the capacity of the 2-D constrained code. Examples include symmetric RLL and density constrained codes...

  1. Energy Cascade Analysis: from Subscale Eddies to Mean Flow

    Science.gov (United States)

    Cheikh, Mohamad Ibrahim; Wonnell, Louis; Chen, James

    2017-11-01

    Understanding the energy transfer between eddies and mean flow can provide insights into the energy cascade process. Much work has been done to investigate the energy cascade at the level of the smallest eddies using different numerical techniques derived from the Navier-Stokes equations. These methodologies, however, prove to be computationally inefficient when producing energy spectra for a wide range of length scales. In this regard, Morphing Continuum Theory (MCT) resolves the length-scales issues by assuming the fluid continuum to be composed of inner structures that play the role of subscale eddies. The current study show- cases the capabilities of MCT in capturing the dynamics of energy cascade at the level of subscale eddies, through a supersonic turbulent flow of Mach 2.93 over an 8× compression ramp. Analysis of the results using statistical averaging procedure shows the existence of a statistical coupling of the internal and translational kinetic energy fluctuations with the corresponding rotational kinetic energy of the subscale eddies, indicating a multiscale transfer of energy. The results show that MCT gives a new characterization of the energy cascade within compressible turbulence without the use of excessive computational resources. This material is based upon work supported by the Air Force Office of Scientific Research under Award Number FA9550-17-1-0154.

  2. A nine-level hybrid symmetric cascaded multilevel converter for ...

    Indian Academy of Sciences (India)

    Indrajit Sarkar

    Therefore, due to this limitation of asymmetric or hybrid cascaded converters on input power quality, the use of these converters is popular for electric vehicle applications, and have limited industrial use [20]. Several attempts have been made to increase the number of output voltage levels of symmetric CHB–MLCs as well.

  3. Successful Treatment Of Homozygous Familial Hypercholesterolemia Using Cascade Filtration Plasmapheresis

    Directory of Open Access Journals (Sweden)

    Fatih Kardas

    2012-12-01

    Full Text Available OBJECTIVE: The aim of our study is to discuss the efficacy of low-density lipoprotein-cholesterol (LDL-C apheresis procedure using the cascade filtration system for pediatric patients with homozygous familial hypercholesterolemia (FH, and to clarify the adverse effects and difficulties. METHODS: LDL apheresis using the cascade filtration system was performed in 3 pediatric patients with homozygous FH. In total, 120 apheresis sessions were performed for all patients. RESULTS: Cascade filtration therapy significantly reduced the mean LDL-C values from 418 ± 62 mg/dl to 145 ± 43 mg/dl (p<0.05. We determined an acute mean reduction in the plasma levels of total cholesterol (57.9%, LDL cholesterol (70.8%, and high-density lipoprotein (HDL cholesterol (40.7%. Treatments were well tolerated. The most frequent clinical adverse effects were hypotension in 3 sessions (2.5%, chills/feeling cold (1.7% in 2 sessions, and nausea and vomiting in 3 sessions (2.5%. CONCLUSION: Our experience with three patients using the cascade filtration system were, good clinical outcomes, laboratory findings, safety of usage, minor adverse effects and technical problems.

  4. Thresholds and Complex Dynamics of Interdependent Cascading Infrastructure Systems

    Science.gov (United States)

    Carreras, B. A.; Newman, D. E.; Dobson, I.; Lynch, V. E.; Gradney, Paul

    Critical infrastructures have a number of the characteristic properties of complex systems. Among these are infrequent large failures through cascading events. These events, though infrequent, often obey a power law distribution in their probability versus size which suggests that conventional risk analysis does not apply to these systems. Real infrastructure systems typically have an additional layer of complexity, namely the heterogeneous coupling to other infrastructure systems that can allow a failure in one system to propagate to the other system. Here, we model the infrastructure systems through a network with complex system dynamics. We use both mean field theory to get analytic results and a numerical complex systems model, Demon, for computational results. An isolated system has bifurcated fixed points and a cascading threshold which is the same as the bifurcation point. When systems are coupled, this is no longer true and the cascading threshold is different from the bifurcation point of the fixed point solutions. This change in the cascading threshold caused by the interdependence of the system can have an impact on the "safe operation" of interdependent infrastructure systems by changing the critical point and even the power law exponent.

  5. Numerical optimization of a transcritical CO2/propylene cascaded ...

    Indian Academy of Sciences (India)

    application. Parallel compression economization is one of the promising cycle mod- ifications to improve the COP of transcritical CO2 cascaded systems. In this paper, ... liquefaction of petroleum vapors and natural gas, manufacturing of dry ice, precipitation hard- ening of special ..... first and second laws of thermodynamics.

  6. Reliable Broadcast under Cascading Failures in Interdependent Networks

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Sisi [ORNL; Lee, Sangkeun (Matt) [ORNL; Chinthavali, Supriya [ORNL; Shankar, Mallikarjun (Arjun) [ORNL

    2017-01-01

    Reliable broadcast is an essential tool to disseminate information among a set of nodes in the presence of failures. We present a novel study of reliable broadcast in interdependent networks, in which the failures in one network may cascade to another network. In particular, we focus on the interdependency between the communication network and power grid network, where the power grid depends on the signals from the communication network for control and the communication network depends on the grid for power. In this paper, we build a resilient solution to handle crash failures in the communication network that may cause cascading failures and may even partition the network. In order to guarantee that all the correct nodes deliver the messages, we use soft links, which are inactive backup links to non-neighboring nodes that are only active when failures occur. At the core of our work is a fully distributed algorithm for the nodes to predict and collect the information of cascading failures so that soft links can be maintained to correct nodes prior to the failures. In the presence of failures, soft links are activated to guarantee message delivery and new soft links are built accordingly for long term robustness. Our evaluation results show that the algorithm achieves low packet drop rate and handles cascading failures with little overhead.

  7. Probing supersymmetry with third-generation cascade decays

    Energy Technology Data Exchange (ETDEWEB)

    Graesser, Michael [Los Alamos National Laboratory; Shelton, Jessie [RUTGERS UNIV

    2008-01-01

    The chiral structure of supersymmetric particle couplings involving third generation Standard Model fermions depends on left-right squark and slepton mixings as well as gaugino-higgsino mixings. The shapes and intercorrelations of invariant mass distributions of a first or second generation lepton with bottoms and taus arising from adjacent branches of SUSY cascade decays are shown to be a sensitive probe of this chiral structure. All possible cascade decays that can give rise to such correlations within the MSSM are considered. For bottom-lepton correlations the distinctive structure of the invariant mass distributions distinguishes between decays originating from stop or sbottom squarks through either an intermediate chargino or neutralino. For decay through a chargino the spins of the stop and chargino are established by the form of the distribution. When the bottom charge is signed through soft muon tagging, the structure of the same-sign and opposite-sign invariant mass distributions depends on a set function of left-right and gaugino-higgsino mixings, as well as establishes the spins of all the superpartners in the sequential two-body cascade decay. Tau-lepton and tau-tau invariant mass distributions arising from MSSM cascade decays are likewise systematically considered with particular attention to their dependence on tau polarization. All possible tau-lepton and tau-tau distributions are plotted using a semi-analytic model for hadronic one-prong taus. Algorithms for fitting tau-tau and tau-lepton distributions to data are suggested.

  8. Numerical optimization of a transcritical CO2/propylene cascaded ...

    Indian Academy of Sciences (India)

    Use of organic refrigerants such as Hydrochlorofluorocarbons and Chlorofluorocarbons have been criticized for their adverse impact on the Earth's protective ozone layer and for their significant global warming potential (GWP). CO2 has been receiving great concern as an alternative refrigerant. Cascade refrigeration ...

  9. Fire severity in intermittent stream drainages, Western Cascade Range, Oregon.

    Science.gov (United States)

    Jennifer E. Tollefson; Frederick J. Swanson; John H. Cissel

    2004-01-01

    We quantified fire severity patterns within intermittent stream drainages in a recently burned area of the central western Cascades, Oregon. Aerial photographs were used to estimate post fire live canopy cover within streamside and upland zones on the southeast and southwest-facing slopes of 33 watersheds. Live canopy cover did not differ significantly between...

  10. DISPLACEMENT CASCADE SIMULATION IN TUNGSTEN AT 1025 K

    Energy Technology Data Exchange (ETDEWEB)

    Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.; Heinisch, Howard L.; Kurtz, Richard J.; Wirth, Brian D.

    2013-09-30

    Molecular dynamics simulation was employed to investigate the irradiation damage properties of bulk tungsten at 1025 K (0.25 melting temperature). A comprehensive data set of primary cascade damage was generated up to primary knock-on atom (PKA) energies 100 keV. The dependence of the number of surviving Frenkel pairs (NFP) on the PKA energy (E) exhibits three different characteristic domains presumably related to the different cascade morphologies that form. The low-energy regime < 0.2 keV is characterized by a hit-or-miss type of Frenkel pair (FP) production near the displacement threshold energy of 128 eV. The middle regime 0.3 – 30 keV exhibits a sublinear dependence of log(NFP) vs log(E) associated with compact cascade morphology with a slope of 0.73. Above 30 keV, the cascade morphology consists of complex branches or interconnected damage regions. In this extended morphology, large interstitial clusters form from superposition of interstitials from nearby damage regions. Strong clustering above 30 keV results in a superlinear dependence of log(NFP) vs log(E) with a slope of 1.365. At 100 keV, an interstitial cluster of size 92 and a vacancy cluster of size 114 were observed.

  11. Gamma irradiation of Fabry–Perot interband cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Myers, Tanya L. [Pacific Northwest National Laboratory, Richland, Washington; Cannon, Bret D. [Pacific Northwest National Laboratory, Richland, Washington; Brauer, Carolyn S. [Pacific Northwest National Laboratory, Richland, Washington; Canedy, Chadwick L. [Naval Research Laboratory, Washington, DC; Kim, Chul Soo [Naval Research Laboratory, Washington, DC; Kim, Mijin [Sotera Defense Solutions, Inc., Columbia, Maryland; Merritt, Charles D. [Naval Research Laboratory, Washington, DC; Bewley, William W. [Naval Research Laboratory, Washington, DC; Vurgaftman, Igor [Naval Research Laboratory, Washington, DC; Meyer, Jerry R. [Naval Research Laboratory, Washington, DC

    2017-09-20

    Two Fabry-Perot interband cascade lasers (ICLs) were exposed to Cobalt-60 gamma rays for a dosage of 500 krad(Si) each, which is higher than is typically encountered in space applications. The ICLs do not show any significant changes in threshold current or slope efficiency, suggesting the suitability of ICLs for use in radiation environments.

  12. ECG classification and abnormality detection using cascade forward ...

    African Journals Online (AJOL)

    user

    different networks and different algorithms are compared, it is found that to identify whether the ECG beat is normal or abnormal, cascade forward back network algorithm has shown 99.9 % correct classification. These results are compared with previous neural network techniques and found that method proposed in this ...

  13. Effect of field quantization on Rabi oscillation of equidistant cascade ...

    Indian Academy of Sciences (India)

    We have exactly solved a model of equidistant cascade four-level system interacting with a single-mode radiation field both semiclassically and quantum mechanically by exploiting its similarity with Jaynes-Cummings model. For the classical field, it is shown that the Rabi oscillation of the system initially in the first level ...

  14. Effect of field quantization on Rabi oscillation of equidistant cascade ...

    Indian Academy of Sciences (India)

    Abstract. We have exactly solved a model of equidistant cascade four-level system inter- acting with a single-mode radiation field both semiclassically and quantum mechanically by exploiting its similarity with Jaynes–Cummings model. For the classical field, it is shown that the Rabi oscillation of the system initially in the first ...

  15. Low crosstalk Arrayed Waveguide Grating with Cascaded Waveguide Grating Filter

    Energy Technology Data Exchange (ETDEWEB)

    Deng Yang; Liu Yuan; Gao Dingshan, E-mail: dsgao@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2011-02-01

    We propose a highly compact and low crosstalk arrayed waveguide grating (AWG) with cascaded waveguide grating (CWGF). The side lobes of the silicon nanowire AWG, which are normally introduced by fabrication errors, can be effectively suppressed by the CWGF. And the crosstalk can be improved about 15dB.

  16. Cascade reactions in an all-enzyme nanoreactor

    NARCIS (Netherlands)

    Delaittre, Guillaume; Reynhout, Irene C.; Cornelissen, Jeroen Johannes Lambertus Maria; Nolte, Roeland J.M.

    2009-01-01

    Good things come in small packages! Giant amphiphiles, consisting of a polymeric hydrophobic tail and a horseradish peroxidase head, were simultaneously synthesized and self-assembled into vesicles. During the self-assembly process, glucose oxidase was encapsulated to create enzymatic cascade

  17. Mitogen-activated protein kinase cascades in Vitis vinifera.

    Science.gov (United States)

    Çakır, Birsen; Kılıçkaya, Ozan

    2015-01-01

    Protein phosphorylation is one of the most important mechanisms to control cellular functions in response to external and endogenous signals. Mitogen-activated protein kinases (MAPK) are universal signaling molecules in eukaryotes that mediate the intracellular transmission of extracellular signals resulting in the induction of appropriate cellular responses. MAPK cascades are composed of four protein kinase modules: MAPKKK kinases (MAPKKKKs), MAPKK kinases (MAPKKKs), MAPK kinases (MAPKKs), and MAPKs. In plants, MAPKs are activated in response to abiotic stresses, wounding, and hormones, and during plant pathogen interactions and cell division. In this report, we performed a complete inventory of MAPK cascades genes in Vitis vinifera, the whole genome of which has been sequenced. By comparison with MAPK, MAPK kinases, MAPK kinase kinases and MAPK kinase kinase kinase kinase members of Arabidopsis thaliana, we revealed the existence of 14 MAPKs, 5 MAPKKs, 62 MAPKKKs, and 7 MAPKKKKs in Vitis vinifera. We identified orthologs of V. vinifera putative MAPKs in different species, and ESTs corresponding to members of MAPK cascades in various tissues. This work represents the first complete inventory of MAPK cascades in V. vinifera and could help elucidate the biological and physiological functions of these proteins in V. vinifera.

  18. Separation of an inulin mixture using cascaded nanofiltration

    NARCIS (Netherlands)

    Patil, N.V.; Feng, Xiaoxia; Sewalt, J.J.W.; Boom, R.M.; Janssen, A.E.M.

    2015-01-01

    This paper examines the use of a pilot-scale spiral wound nanofiltration cascade with regard to separation of mono- and disaccharides from a mixture of inulin of different polymer sizes. The choices of the membrane and operational conditions were based on single stage experiments. Two 3-stage

  19. Checklist of vertebrate animals of the Cascade Head Experimental Forest.

    Science.gov (United States)

    Chris Maser; Jerry F. Franklin

    1974-01-01

    Three months, April and August 1971 and August 1972, were spent studying the vertebrate fauna of Cascade Head Experimental Forest. The resulting annotated checklist includes 9 amphibians, 2 reptiles, 35 birds, and 40 mammals. A standardized animal habitat classification is presented in an effort to correlate the vertebrates in some meaningful way to their environment...

  20. Aspects of microstructure evolution under cascade damage conditions

    DEFF Research Database (Denmark)

    Singh, B.N.; Golubov, S.I.; Trinkaus, H.

    1997-01-01

    The conventional theoretical models describing the damage accumulation, particularly void swelling, under cascade damage conditions do not include treatments of important features such as intracascade clustering of self-interstitial atoms (SIAs) and one-dimensional glide of SIA clusters produced...

  1. Intensity correlations and anticorrelations in a three-level cascade ...

    Indian Academy of Sciences (India)

    Intensity correlations; two-photon coherence; non-classical light; three-level cascade system; incoherent pumping. ... Further, we show that by applying even a very weak incoherent pump, the nature of the emitted radiation can be switched from classical to non-classicalwithout significantly affecting the probe transparency ...

  2. Extension of CASCADE.04 to estimate neutron fluence and dose ...

    Indian Academy of Sciences (India)

    neutron source situated at the centre of the paraffin cylinder as described above and obtained neutron fluences at different radial distances from both the codes. The results of fluence per unit incident neutron are compared in figure 3. The cal- culated values from CASCADE.04.d code are close to that of the values obtained.

  3. A network approach for power grid robustness against cascading failures

    NARCIS (Netherlands)

    Wang, X.; Koç, Y.; Kooij, R.E.; Mieghem, P. van

    2015-01-01

    Cascading failures are one of the main reasons for blackouts in electrical power grids. Stable power supply requires a robust design of the power grid topology. Currently, the impact of the grid structure on the grid robustness is mainly assessed by purely topological metrics, that fail to capture

  4. Learning from a role model: A cascade or whirlpool effect?

    NARCIS (Netherlands)

    Jochemsen-van der Leeuw, H. G. A. Ria; Buwalda, Nienke; Wieringa-de Waard, Margreet; van Dijk, Nynke

    2015-01-01

    Continuing Professional Development (CPD) and Faculty Development (FD) courses have been designed in the expectation that a cascade effect will occur, consisting of a conveyance of information from the courses to clinical trainers to daily practice and/or to trainees by means of role modeling. The

  5. Cascading pressure reactor and method for solar-thermochemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Ermanoski, Ivan

    2017-11-14

    Reactors and methods for solar thermochemical reactions are disclosed. The reactors and methods include a cascade of reduction chambers at successively lower pressures that leads to over an order of magnitude pressure decrease compared to a single-chambered design. The resulting efficiency gains are substantial, and represent an important step toward practical and efficient solar fuel production on a large scale.

  6. Experiments on Cascaded Quadratic Soliton Compression in Unpoled LN Waveguide

    DEFF Research Database (Denmark)

    Guo, Hairun; Zhou, Binbin; Zeng, Xianglong

    2014-01-01

    Experiments on cascaded quadratic soliton compression in unpoled phasemismatched lithium niobate waveguides are presented. Pulse self-phasemodulation dominated by an overall self-defocusing nonlinearity is observed, with an variation of pump wavelength and waveguide core width. © 2014 Optical...... Society of America...

  7. Network protection against worms and cascading failures using modularity partitioning

    NARCIS (Netherlands)

    Omic, J.; Hernandez, J.M.; Van Mieghem, P.

    2010-01-01

    Communication networks are prone to virus and worms spreading and cascading failures. Recently, a number of social networking worms have spread over public Web sites. Another example is error propagation in routing tables, such as in BGP tables. The immunization and error curing applied to these

  8. Mitogen-activated protein kinase cascades in Vitis vinifera

    Science.gov (United States)

    Çakır, Birsen; Kılıçkaya, Ozan

    2015-01-01

    Protein phosphorylation is one of the most important mechanisms to control cellular functions in response to external and endogenous signals. Mitogen-activated protein kinases (MAPK) are universal signaling molecules in eukaryotes that mediate the intracellular transmission of extracellular signals resulting in the induction of appropriate cellular responses. MAPK cascades are composed of four protein kinase modules: MAPKKK kinases (MAPKKKKs), MAPKK kinases (MAPKKKs), MAPK kinases (MAPKKs), and MAPKs. In plants, MAPKs are activated in response to abiotic stresses, wounding, and hormones, and during plant pathogen interactions and cell division. In this report, we performed a complete inventory of MAPK cascades genes in Vitis vinifera, the whole genome of which has been sequenced. By comparison with MAPK, MAPK kinases, MAPK kinase kinases and MAPK kinase kinase kinase kinase members of Arabidopsis thaliana, we revealed the existence of 14 MAPKs, 5 MAPKKs, 62 MAPKKKs, and 7 MAPKKKKs in Vitis vinifera. We identified orthologs of V. vinifera putative MAPKs in different species, and ESTs corresponding to members of MAPK cascades in various tissues. This work represents the first complete inventory of MAPK cascades in V. vinifera and could help elucidate the biological and physiological functions of these proteins in V. vinifera. PMID:26257761

  9. Errata Field theoretic calculation of energy cascade rates in non ...

    Indian Academy of Sciences (India)

    Errata. Field theoretic calculation of energy cascade rates in non-helical magnetohydrodynamic turbulence. MAHENDRA K VERMA. (Pramana – J. Phys., Vol. 61, No. 3, pp. 577–594 (2003)). In our paper we committed some typographical errors. We are correcting them here. 1. In eqs (25) and (26), 〈Sub(k |p|q)〉 and 〈Sbu(k ...

  10. A comparative study on dual colour soft aperture cascaded second ...

    Indian Academy of Sciences (India)

    2014-02-09

    Feb 9, 2014 ... A comparative study in terms of optimized output power and stability is made on cascaded second-order nonlinear optical mode-locking with KTP, BBO and LBO crystals for both 1064 nm and 532 nm. Large nonlinear optical phase shift achieved in a non-phase-matched second harmonic generating crystal ...

  11. Neutron spallation source and the Dubna Cascade Code

    Indian Academy of Sciences (India)

    into a stationary state sometimes emitting several nucleons. At the third and the last stage the excited residual nucleus decays by competitive successive evaporation of nucleons, fission and emission of γ-quanta. Dubna Cascade Code [4] developed for the purpose of mathematical modeling of ADSS allows one to estimate ...

  12. A cascaded online uninterruptible power supply using reduced semiconductor

    DEFF Research Database (Denmark)

    Zhang, Lei; Loh, Poh Chiang; Gao, Feng

    2011-01-01

    are experienced by the presented UPS, as guaranteed through proper topological and control design. Advantages of the cascaded UPS can therefore be summarized as reduced system cost, improved redundancy, better waveform quality and the same reliable protection expected from an online system. The only disadvantage...

  13. An Algebraic Approach to Signaling Cascades with n Layers

    DEFF Research Database (Denmark)

    Feliu, Elisenda; Knudsen, Michael; Andersen, Lars Nørvang

    2011-01-01

    Posttranslational modification of proteins is key in transmission of signals in cells. Many signaling pathways contain several layers of modification cycles that mediate and change the signal through the pathway. Here, we study a simple signaling cascade consisting of n layers of modification...

  14. Cascade: an RNA-seq visualization tool for cancer genomics.

    Science.gov (United States)

    Shifman, Aaron R; Johnson, Radia M; Wilhelm, Brian T

    2016-01-25

    Cancer genomics projects are producing ever-increasing amounts of rich and diverse data from patient samples. The ability to easily visualize this data in an integrated an intuitive way is currently limited by the current software available. As a result, users typically must use several different tools to view the different data types for their cohort, making it difficult to have a simple unified view of their data. Here we present Cascade, a novel web based tool for the intuitive 3D visualization of RNA-seq data from cancer genomics experiments. The Cascade viewer allows multiple data types (e.g. mutation, gene expression, alternative splicing frequency) to be simultaneously displayed, allowing a simplified view of the data in a way that is tuneable based on user specified parameters. The main webpage of Cascade provides a primary view of user data which is overlaid onto known biological pathways that are either predefined or added by users. A space-saving menu for data selection and parameter adjustment allows users to access an underlying MySQL database and customize the features presented in the main view. There is currently a pressing need for new software tools to allow researchers to easily explore large cancer genomics datasets and generate hypotheses. Cascade represents a simple yet intuitive interface for data visualization that is both scalable and customizable.

  15. Neutron spallation source and the Dubna Cascade Code

    Indian Academy of Sciences (India)

    Neutron multiplicity per incident proton, /, in collision of high energy proton beam with voluminous Pb and W targets has been estimated from the Dubna Cascade Code and compared with the available experimental data for the purpose of benchmarking of the code. Contributions of various atomic and nuclear processes ...

  16. Gravity's kiss the detection of gravitational waves

    CERN Document Server

    Collins, Harry

    2017-01-01

    Scientists have been trying to confirm the existence of gravitational waves for fifty years. Then, in September 2015, came a "very interesting event" (as the cautious subject line in a physicist's email read) that proved to be the first detection of gravitational waves. In Gravity's Kiss, Harry Collins -- who has been watching the science of gravitational wave detection for forty-three of those fifty years and has written three previous books about it -- offers a final, fascinating account, written in real time, of the unfolding of one of the most remarkable scientific discoveries ever made. Predicted by Einstein in his theory of general relativity, gravitational waves carry energy from the collision or explosion of stars. Dying binary stars, for example, rotate faster and faster around each other until they merge, emitting a burst of gravitational waves. It is only with the development of extraordinarily sensitive, highly sophisticated detectors that physicists can now confirm Einstein's prediction. This is...

  17. Wave packet systems on local fields

    Science.gov (United States)

    Shah, Firdous A.; Ahmad, Owais

    2017-10-01

    In this paper, we introduce the notion of wave packet systems on local fields of positive characteristic and derive some characterizations of these systems by means of two basic equations in the Fourier domain. More precisely, we establish a complete characterization of orthogonal wave packet systems in L2(K) which include the corresponding results of wavelet analysis and Gabor theory as the special cases. We shall also provide a sufficient condition of the completeness of wave packet systems on local fields of positive characteristic subject to some mild conditions. The paper concludes with the necessary and sufficient conditions for the wave packet systems to be wave packet Parseval frames for L2(K) .

  18. Microstructural Design for Stress Wave Energy Management

    Science.gov (United States)

    2013-04-01

    dissipation (i.e. viscoelasticity ) to control the amplitude, energy, and direction of propagating stress-waves in a multilayered structure. 15. SUBJECT...Polyurea based foam 7 4) Controlling transmission and reflection of pressure and shear waves in a multilayered anisotropic structure 10 5...methods with conventional mechanisms for shear dissipation (i.e. viscoelasticity ) to control the amplitude, energy, and direction of propagating stress

  19. Wave disc engine apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Muller, Norbert; Piechna, Janusz; Sun, Guangwei; Parraga, Pablo-Francisco

    2018-01-02

    A wave disc engine apparatus is provided. A further aspect employs a constricted nozzle in a wave rotor channel. A further aspect provides a sharp bend between an inlet and an outlet in a fluid pathway of a wave rotor, with the bend being spaced away from a peripheral edge of the wave rotor. A radial wave rotor for generating electricity in an automotive vehicle is disclosed in yet another aspect.

  20. Development of a New Cascade Voltage-Doubler for Voltage Multiplication

    Directory of Open Access Journals (Sweden)

    Arash Toudeshki

    2014-01-01

    Full Text Available For more than eight decades, cascade voltage-doubler circuits are used as a method to produce DC output voltage higher than the input voltage. In this paper, the topological developments of cascade voltage-doublers are reviewed. A new circuit configuration for cascade voltage-doubler is presented. This circuit can produce a higher value of the DC output voltage and better output quality compared to the conventional cascade voltage-doubler circuits, with the same number of stages.