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Sample records for weak counter-propagating pulse

  1. Atomic Interferometry with Detuned Counter-Propagating Electromagnetic Pulses

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, Ming -Yee [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-09-05

    Atomic fountain interferometry uses atoms cooled with optical molasses to 1 μK, which are then launched in a fountain mode. The interferometer relies on the nonlinear Raman interaction of counter-propagating visible light pulses. We present models of these key transitions through a series of Hamiltonians. Our models, which have been verified against special cases with known solutions, allow us to incorporate the effects of non-ideal pulse shapes and realistic laser frequency or wavevector jitter.

  2. Correlation between light-flux fluctuations of two counter-propagating waves in weak atmospheric turbulence.

    Science.gov (United States)

    Chen, Chunyi; Yang, Huamin

    2017-05-29

    Expressions for the correlation coefficient between light-flux fluctuations of two waves counter-propagating along a common path in weak turbulence are developed. Only the aperture and inner-scale Fresnel parameters are needed for evaluation of the correlation coefficient if the turbulence spectrum has no path dependence, and of the path weighting functions for the cross-covariance and variances of normalized light-flux fluctuations if the turbulence spectrum is dependent on path locations. Under the condition that atmospheric turbulence is statistically homogeneous over a path, although good correlation between light-flux fluctuations of two counter-propagating spherical waves may be achieved for a relatively small aperture Fresnel parameter or relatively large inner-scale Fresnel parameter, the correlation coefficient between light-flux fluctuations of two counter-propagating plane waves is always lower than 1 obviously. When the aperture Fresnel parameter becomes larger than the inner-scale Fresnel parameter, the inner scale of turbulence tends to play an unimportant role in determining the correlation coefficient.

  3. Cooling and trapping of atoms and molecules by the counter-propagating pulses trains

    CERN Document Server

    Romanenko, V I; Romanenko, A V; Yatsenko, L P

    2014-01-01

    We discuss a possible one-dimensional trapping and cooling of atoms and molecules due to their non-resonant interaction with the counter-propagating light pulses trains. The counter-propagating pulses form a one-dimensional trap for atoms and molecules, and properly chosen the carrier frequency detuning from the transition frequency of the atoms or molecules keeps the "temperature" of the atomic or molecular ensemble close to the Doppler cooling limit. The calculation by the Monte-Carlo wave function method is carried out for the two-level and three-level schemes of the atom's and the molecule's interaction with the field, correspondingly. The discussed models are applicable to atoms and molecules with almost diagonal Frank-Condon factor arrays. Illustrative calculations where carried out for ensemble averaged characteristics for sodium atoms and SrF molecules in the trap. Perspective for the nanoparticle light pulses's trap formed by counter-propagating light pulses trains is also discussed.

  4. Mapping surface plasmon polariton propagation via counter-propagating light pulses

    DEFF Research Database (Denmark)

    Lemke, Christoph; Leißner, Till; Jauernik, Stephan

    2012-01-01

    In an interferometric time-resolved photoemission electron microscopy (ITR-PEEM) experiment, the near-field associated with surface plasmon polaritons (SPP) can be locally sensed via interference with ultrashort laser pulses. Here, we present ITR-PEEM data of SPP propagation at a gold vacuum...

  5. Counter-propagating patterns in the BioPhotonics Workstation

    DEFF Research Database (Denmark)

    Palima, Darwin; Lindballe, T.; Kristensen, M.V.

    2010-01-01

    The counter-propagating geometry opens an extra degree of freedom for shaping light while subsuming single-sided illumination as a special case (i.e., one beam set turned off). In its conventional operation, our BioPhotonics Workstation (BWS) uses symmetric, co-axial counter-propagating beams...

  6. Counter-propagating wave interaction for contrast-enhanced ultrasound imaging

    Science.gov (United States)

    Renaud, G.; Bosch, J. G.; ten Kate, G. L.; Shamdasani, V.; Entrekin, R.; de Jong, N.; van der Steen, A. F. W.

    2012-11-01

    Most techniques for contrast-enhanced ultrasound imaging require linear propagation to detect nonlinear scattering of contrast agent microbubbles. Waveform distortion due to nonlinear propagation impairs their ability to distinguish microbubbles from tissue. As a result, tissue can be misclassified as microbubbles, and contrast agent concentration can be overestimated; therefore, these artifacts can significantly impair the quality of medical diagnoses. Contrary to biological tissue, lipid-coated gas microbubbles used as a contrast agent allow the interaction of two acoustic waves propagating in opposite directions (counter-propagation). Based on that principle, we describe a strategy to detect microbubbles that is free from nonlinear propagation artifacts. In vitro images were acquired with an ultrasound scanner in a phantom of tissue-mimicking material with a cavity containing a contrast agent. Unlike the default mode of the scanner using amplitude modulation to detect microbubbles, the pulse sequence exploiting counter-propagating wave interaction creates no pseudoenhancement behind the cavity in the contrast image.

  7. Co- and Counter- propagating fields in an four level `N-scheme'

    Science.gov (United States)

    Narducci, Frank A.; Davis, Jon P.

    2012-06-01

    A four level ``N-scheme'' atomic system consists of a standard λ EIT configuration with an additional level being driven by an additional switch field. We theoretically extend our earlier studies of this model to include a counter-propagating, weak probe field. We investigate the dispersion experienced by the weak probe under a variety of conditions including cold and warm samples, as well as weak and strong switching fields. We find conditions in which the forward propagating probe field experiences normal dispersion while the backward propagating field experiences negative dispersion. We examine regions of high dispersion with vanishing absorption. We discuss applications of our results to high-dispersion gyroscopes.

  8. Real-time reconfigurable counter-propagating beam-traps

    DEFF Research Database (Denmark)

    Tauro, Sandeep; Bañas, Andrew Rafael; Palima, Darwin

    2010-01-01

    We present a versatile technique that enhances the axial stability and range in counter-propagating (CP) beam-geometry optical traps. It is based on computer vision to track objects in unison with software implementation of feedback to stabilize particles. In this paper, we experimentally...... which simulates biosamples. By working on differences rather than absolute values, this feedback based technique makes CPtrapping nullify many of the commonly encountered pertubations such as fluctuations in the laser power, vibrations due to mechanical instabilities and other distortions emphasizing...

  9. Blind quantum computing with weak coherent pulses.

    Science.gov (United States)

    Dunjko, Vedran; Kashefi, Elham; Leverrier, Anthony

    2012-05-18

    The universal blind quantum computation (UBQC) protocol [A. Broadbent, J. Fitzsimons, and E. Kashefi, in Proceedings of the 50th Annual IEEE Symposiumon Foundations of Computer Science (IEEE Computer Society, Los Alamitos, CA, USA, 2009), pp. 517-526.] allows a client to perform quantum computation on a remote server. In an ideal setting, perfect privacy is guaranteed if the client is capable of producing specific, randomly chosen single qubit states. While from a theoretical point of view, this may constitute the lowest possible quantum requirement, from a pragmatic point of view, generation of such states to be sent along long distances can never be achieved perfectly. We introduce the concept of ϵ blindness for UBQC, in analogy to the concept of ϵ security developed for other cryptographic protocols, allowing us to characterize the robustness and security properties of the protocol under possible imperfections. We also present a remote blind single qubit preparation protocol with weak coherent pulses for the client to prepare, in a delegated fashion, quantum states arbitrarily close to perfect random single qubit states. This allows us to efficiently achieve ϵ-blind UBQC for any ϵ>0, even if the channel between the client and the server is arbitrarily lossy.

  10. Blind Quantum Computing with Weak Coherent Pulses

    Science.gov (United States)

    Dunjko, Vedran; Kashefi, Elham; Leverrier, Anthony

    2012-05-01

    The universal blind quantum computation (UBQC) protocol [A. Broadbent, J. Fitzsimons, and E. Kashefi, in Proceedings of the 50th Annual IEEE Symposiumon Foundations of Computer Science (IEEE Computer Society, Los Alamitos, CA, USA, 2009), pp. 517-526.] allows a client to perform quantum computation on a remote server. In an ideal setting, perfect privacy is guaranteed if the client is capable of producing specific, randomly chosen single qubit states. While from a theoretical point of view, this may constitute the lowest possible quantum requirement, from a pragmatic point of view, generation of such states to be sent along long distances can never be achieved perfectly. We introduce the concept of ɛ blindness for UBQC, in analogy to the concept of ɛ security developed for other cryptographic protocols, allowing us to characterize the robustness and security properties of the protocol under possible imperfections. We also present a remote blind single qubit preparation protocol with weak coherent pulses for the client to prepare, in a delegated fashion, quantum states arbitrarily close to perfect random single qubit states. This allows us to efficiently achieve ɛ-blind UBQC for any ɛ>0, even if the channel between the client and the server is arbitrarily lossy.

  11. Superluminal pulse reflection from a weakly absorbing dielectric slab.

    Science.gov (United States)

    Wang, Li-Gang; Zhu, Shi-Yao

    2006-07-15

    Group delay for a reflected light pulse from a weakly absorbing dielectric slab is theoretically investigated, and large negative group delay is found for weak absorption near a resonance of the slab [Re(kd)=mpi]. The group delay for both the reflected and transmitted pulses will be saturated with an increase of the absorption.

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

    Science.gov (United States)

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

    2016-10-01

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

  13. Alternative modes for optical trapping and manipulation using counter-propagating shaped beams

    DEFF Research Database (Denmark)

    Palima, Darwin; Lindballe, T.B.; Kristensen, M.V.

    2011-01-01

    Counter-propagating beams have enabled the first stable three-dimensional optical trapping of microparticles and this procedure has been enhanced and developed over the years to achieve independent and interactive manipulation of multiple particles. In this work, we analyse counter...... that deviating from using perfectly counter-propagating beams to use oblique beams can improve the axial stability of the traps and improve the axial trapping stiffness. These alternative geometries can be particularly useful for handling larger particles. These results hint at a rich potential for light shaping......-propagating shaped-beam traps that depart from the conventional geometry based on symmetric, coaxial counter-propagating beams. We show that projecting shaped beams with separation distances previously considered axially unstable can, in fact, enhance the axial and transverse trapping stiffnesses. We also show...

  14. Dispersion in a four level N-scheme atomic system with co- and counter- propagating beams

    Science.gov (United States)

    Davis, J. P.; Narducci, F. A.

    2012-03-01

    We motivate the study of an 'N-scheme' atomic system for the case of a bi-directional probe field. We derive the equations of motion. The equations were expanded in order of the counter-propagating field strength over the co-propagating field strength. We solve the equations numerically in steady state in a perturbative manner. The zeroth order solutions describe the dispersion and absorption of the co-propagating field, while the first order solutions describe the dispersion and absorption of the counter-propagating field. We investigate the solutions in two temperature regimes for a variety of field strengths. Regimes of similar dispersion for the co- and counter-propagating fields were found, as well as regimes of opposite behavior. In most cases, absorption of the fields is still a problem.

  15. The instability of counter-propagating kernel gravity waves in a constant shear flow

    CERN Document Server

    Umurhan, O M; Harnik, N; Lott, F

    2007-01-01

    The mechanism describing the recently developed notion of kernel gravity waves (KGWs) is reviewed and such structures are employed to interpret the unstable dynamics of an example stratified plane parallel shear flow. This flow has constant vertical shear, is infinite in the vertical extent, and characterized by two density jumps of equal magnitude each decreasing successively with height, in which the jumps are located symmetrically away from the midplane of the system. We find that for a suitably defined bulk-Richardson number there exists a band of horizontal wavenumbers which exhibits normal-mode instability. The instability mechanism closely parallels the mechanism responsible for the instability seen in the problem of counter-propagating Rossby waves. In this problem the instability arises out of the interaction of counter-propagating gravity waves. We argue that the instability meets the Hayashi-Young criterion for wave instability. We also argue that the instability is the simplest one that can arise ...

  16. Polarization attraction using counter-propagating waves in optical fiber at telecommunication wavelengths.

    Science.gov (United States)

    Pitois, S; Fatome, J; Millot, G

    2008-04-28

    In this work, we report the experimental observation of a polarization attraction process which can occur in optical fibers at telecommunication wavelengths. More precisely, we have numerically and experimentally shown that a polarization attractor, based on the injection of two counter-propagating waves around 1.55microm into a 2-m long high nonlinear fiber, can transform any input polarization state into a unique well-defined output polarization state.

  17. Experimental demonstration of robust entanglement distribution over reciprocal noisy channels assisted by a counter-propagating classical reference light.

    Science.gov (United States)

    Ikuta, Rikizo; Nozaki, Shota; Yamamoto, Takashi; Koashi, Masato; Imoto, Nobuyuki

    2017-07-06

    Embedding a quantum state in a decoherence-free subspace (DFS) formed by multiple photons is one of the promising methods for robust entanglement distribution of photonic states over collective noisy channels. In practice, however, such a scheme suffers from a low efficiency proportional to transmittance of the channel to the power of the number of photons forming the DFS. The use of a counter-propagating coherent pulse can improve the efficiency to scale linearly in the channel transmission, but it achieves only protection against phase noises. Recently, it was theoretically proposed [Phys. Rev. A 87, 052325(2013)] that the protection against bit-flip noises can also be achieved if the channel has a reciprocal property. Here we experimentally demonstrate the proposed scheme to distribute polarization-entangled photon pairs against a general collective noise including the bit flip noise and the phase noise. We observed an efficient sharing rate scaling while keeping a high quality of the distributed entangled state. Furthermore, we show that the method is applicable not only to the entanglement distribution but also to the transmission of arbitrary polarization states of a single photon.

  18. Interaction of super intense laser pulses with thin foil: Dopler transformation of coherent light into X-ray and gamma-ray bands

    OpenAIRE

    Cherepenin, Vladimir A.; Kulagin, Victor V.

    2001-01-01

    The formation of relativistic electron mirror produced via ionization of thin solid target by ultraintense femtosecond laser pulse is considered with the help of computer simulations. It is shown that the reflection of weak counter-propagating wave from such a mirror can produce the coherent radiation in X-ray and gamma-ray bands. The spectrum of up-conversed radiation is investigated.

  19. Atoms in the counter-propagating frequency-modulated waves: splitting, cooling, confinement

    Science.gov (United States)

    Romanenko, Victor I.; Kornilovska, Nataliya V.

    2017-09-01

    We show that the counter-propagating frequency-modulated (FM) waves of the same intensity can split an orthogonal atomic beam into two beams. We calculate the temperature of the atomic ensemble for the case when the atoms are grouped around zero velocity in the direction of the waves propagation. The high-intensity laser radiation with a properly chosen carrier frequency can form a one-dimensional trap for atoms. We carry out the numerical simulation of the atomic motion (two-level model of the atom-field interaction) using parameters appropriate for sodium atoms and show that sub-Doppler cooling can be reached. We suppose that such a cooling is partly based on the cooling without spontaneous emission in polychromatic waves [H. Metcalf, Phys. Rev. A 77, 061401 (2008)]. We calculate the state of the atom in the field by the Monte Carlo wave-function method and describe its mechanical motion by the classical mechanics.

  20. Optical trapping of nanoparticles with significantly reduced laser powers by using counter-propagating beams (Presentation Recording)

    Science.gov (United States)

    Zhao, Chenglong; LeBrun, Thomas W.

    2015-08-01

    Gold nanoparticles (GNP) have wide applications ranging from nanoscale heating to cancer therapy and biological sensing. Optical trapping of GNPs as small as 18 nm has been successfully achieved with laser power as high as 855 mW, but such high powers can damage trapped particles (particularly biological systems) as well heat the fluid, thereby destabilizing the trap. In this article, we show that counter propagating beams (CPB) can successfully trap GNP with laser powers reduced by a factor of 50 compared to that with a single beam. The trapping position of a GNP inside a counter-propagating trap can be easily modulated by either changing the relative power or position of the two beams. Furthermore, we find that under our conditions while a single-beam most stably traps a single particle, the counter-propagating beam can more easily trap multiple particles. This (CPB) trap is compatible with the feedback control system we recently demonstrated to increase the trapping lifetimes of nanoparticles by more than an order of magnitude. Thus, we believe that the future development of advanced trapping techniques combining counter-propagating traps together with control systems should significantly extend the capabilities of optical manipulation of nanoparticles for prototyping and testing 3D nanodevices and bio-sensing.

  1. Soliton-like behavior in fast two-pulse collisions in weakly perturbed linear physical systems

    Science.gov (United States)

    Peleg, Avner; Nguyen, Quan M.; Huynh, Toan T.

    2017-12-01

    We demonstrate that pulses of linear physical systems, weakly perturbed by nonlinear dissipation, exhibit soliton-like behavior in fast collisions. The behavior is demonstrated for linear waveguides with weak cubic loss and for systems described by linear diffusion-advection models with weak quadratic loss. We show that in both systems, the expressions for the collision-induced amplitude shifts due to the nonlinear loss have the same form as the expression for the amplitude shift in a fast collision between two solitons of the cubic nonlinear Schrödinger equation in the presence of weak cubic loss. Our analytic predictions are confirmed by numerical simulations with the corresponding coupled linear evolution models with weak nonlinear loss. These results open the way for studying dynamics of fast collisions between pulses of weakly perturbed linear physical systems in an arbitrary spatial dimension.

  2. Pulsed photothermal phase-shift spectroscopy for weak absorption measurement.

    Science.gov (United States)

    Li, B; Deng, Y; Cheng, J

    1996-04-01

    A novel photothermal phase-shift spectroscopy configuration based on the retro-reflected beam interference has been developed and its operational principle is described. The weak absorption measurement ability of this technique is experimentally proven with a water/ethanol solution of standard Pyronine G dye and the limit of detection is found to be 1.8 x 10(-6) absorbance. Potential applications of the technique are discussed.

  3. Fuzzy Counter Propagation Neural Network Control for a Class of Nonlinear Dynamical Systems

    Directory of Open Access Journals (Sweden)

    Vandana Sakhre

    2015-01-01

    Full Text Available Fuzzy Counter Propagation Neural Network (FCPN controller design is developed, for a class of nonlinear dynamical systems. In this process, the weight connecting between the instar and outstar, that is, input-hidden and hidden-output layer, respectively, is adjusted by using Fuzzy Competitive Learning (FCL. FCL paradigm adopts the principle of learning, which is used to calculate Best Matched Node (BMN which is proposed. This strategy offers a robust control of nonlinear dynamical systems. FCPN is compared with the existing network like Dynamic Network (DN and Back Propagation Network (BPN on the basis of Mean Absolute Error (MAE, Mean Square Error (MSE, Best Fit Rate (BFR, and so forth. It envisages that the proposed FCPN gives better results than DN and BPN. The effectiveness of the proposed FCPN algorithms is demonstrated through simulations of four nonlinear dynamical systems and multiple input and single output (MISO and a single input and single output (SISO gas furnace Box-Jenkins time series data.

  4. Destabilization of counter-propagating TAEs by off-axis, co-current Neutral Beam Injection

    Science.gov (United States)

    Podesta', M.; Fredrickson, E.; Gorelenkova, M.

    2017-10-01

    Neutral Beam injection (NBI) is a common tool to heat the plasma and drive current non-inductively in fusion devices. Energetic particles (EP) resulting from NBI can drive instabilities that are detrimental for the performance and the predictability of plasma discharges. A broad NBI deposition profile, e.g. by off-axis injection aiming near the plasma mid-radius, is often assumed to limit those undesired effects by reducing the radial gradient of the EP density, thus reducing the ``universal'' drive for instabilities. However, this work presents new evidence that off-axis NBI can also lead to undesired effects such as the destabilization of Alfvénic instabilities, as observed in NSTX-U plasmas. Experimental observations indicate that counter propagating toroidal AEs are destabilized as the radial EP density profile becomes hollow as a result of off-axis NBI. Time-dependent analysis with the TRANSP code, augmented by a reduced fast ion transport model (known as kick model), indicates that instabilities are driven by a combination of radial and energy gradients in the EP distribution. Understanding the mechanisms for wave-particle interaction, revealed by the phase space resolved analysis, is the basis to identify strategies to mitigate or suppress the observed instabilities. Work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Contract Number DE-AC02-09CH11466.

  5. Counter-propagating dual-trap optical tweezers based on linear momentum conservation

    Energy Technology Data Exchange (ETDEWEB)

    Ribezzi-Crivellari, M.; Huguet, J. M. [Small Biosystems Lab, Dept. de Fisica Fonamental, Universitat de Barcelona, Avda. Diagonal 647, 08028 Barcelona (Spain); Ritort, F. [Small Biosystems Lab, Dept. de Fisica Fonamental, Universitat de Barcelona, Avda. Diagonal 647, 08028 Barcelona (Spain); Ciber-BBN de Bioingenieria, Biomateriales y Nanomedicina, Instituto de Salud Carlos III, Madrid (Spain)

    2013-04-15

    We present a dual-trap optical tweezers setup which directly measures forces using linear momentum conservation. The setup uses a counter-propagating geometry, which allows momentum measurement on each beam separately. The experimental advantages of this setup include low drift due to all-optical manipulation, and a robust calibration (independent of the features of the trapped object or buffer medium) due to the force measurement method. Although this design does not attain the high-resolution of some co-propagating setups, we show that it can be used to perform different single molecule measurements: fluctuation-based molecular stiffness characterization at different forces and hopping experiments on molecular hairpins. Remarkably, in our setup it is possible to manipulate very short tethers (such as molecular hairpins with short handles) down to the limit where beads are almost in contact. The setup is used to illustrate a novel method for measuring the stiffness of optical traps and tethers on the basis of equilibrium force fluctuations, i.e., without the need of measuring the force vs molecular extension curve. This method is of general interest for dual trap optical tweezers setups and can be extended to setups which do not directly measure forces.

  6. Counter-propagating radiative shock experiments on the Orion laser and the formation of radiative precursors

    Science.gov (United States)

    Clayson, T.; Suzuki-Vidal, F.; Lebedev, S. V.; Swadling, G. F.; Stehlé, C.; Burdiak, G. C.; Foster, J. M.; Skidmore, J.; Graham, P.; Gumbrell, E.; Patankar, S.; Spindloe, C.; Chaulagain, U.; Kozlová, M.; Larour, J.; Singh, R. L.; Rodriguez, R.; Gil, J. M.; Espinosa, G.; Velarde, P.; Danson, C.

    2017-06-01

    We present results from new experiments to study the dynamics of radiative shocks, reverse shocks and radiative precursors. Laser ablation of a solid piston by the Orion high-power laser at AWE Aldermaston UK was used to drive radiative shocks into a gas cell initially pressurised between 0.1 and 1.0 bar with different noble gases. Shocks propagated at 80 ± 10 km/s and experienced strong radiative cooling resulting in post-shock compressions of ×25 ± 2. A combination of X-ray backlighting, optical self-emission streak imaging and interferometry (multi-frame and streak imaging) were used to simultaneously study both the shock front and the radiative precursor. These experiments present a new configuration to produce counter-propagating radiative shocks, allowing for the study of reverse shocks and providing a unique platform for numerical validation. In addition, the radiative shocks were able to expand freely into a large gas volume without being confined by the walls of the gas cell. This allows for 3-D effects of the shocks to be studied which, in principle, could lead to a more direct comparison to astrophysical phenomena. By maintaining a constant mass density between different gas fills the shocks evolved with similar hydrodynamics but the radiative precursor was found to extend significantly further in higher atomic number gases (∼4 times further in xenon than neon). Finally, 1-D and 2-D radiative-hydrodynamic simulations are presented showing good agreement with the experimental data.

  7. Excitation of monochromatic and stable electron acoustic wave by two counter-propagating laser beams

    Science.gov (United States)

    Xiao, C. Z.; Liu, Z. J.; Zheng, C. Y.; He, X. T.

    2017-07-01

    The undamped electron acoustic wave is a newly-observed nonlinear electrostatic plasma wave and has potential applications in ion acceleration, laser amplification and diagnostics due to its unique frequency range. We propose to make the first attempt to excite a monochromatic and stable electron acoustic wave (EAW) by two counter-propagating laser beams. The matching conditions relevant to laser frequencies, plasma density, and electron thermal velocity are derived and the harmonic effects of the EAW are excluded. Single-beam instabilities, including stimulated Raman scattering and stimulated Brillouin scattering, on the excitation process are quantified by an interaction quantity, η =γ {τ }B, where γ is the growth rate of each instability and {τ }B is the characteristic time of the undamped EAW. The smaller the interaction quantity, the more successfully the monochromatic and stable EAW can be excited. Using one-dimensional Vlasov-Maxwell simulations, we excite EAW wave trains which are amplitude tunable, have a duration of thousands of laser periods, and are monochromatic and stable, by carefully controlling the parameters under the above conditions.

  8. Array design considerations for exploitation of stable weakly dispersive modal pulses in the deep ocean

    Science.gov (United States)

    Udovydchenkov, Ilya A.

    2017-07-01

    Modal pulses are broadband contributions to an acoustic wave field with fixed mode number. Stable weakly dispersive modal pulses (SWDMPs) are special modal pulses that are characterized by weak dispersion and weak scattering-induced broadening and are thus suitable for communications applications. This paper investigates, using numerical simulations, receiver array requirements for recovering information carried by SWDMPs under various signal-to-noise ratio conditions without performing channel equalization. Two groups of weakly dispersive modal pulses are common in typical mid-latitude deep ocean environments: the lowest order modes (typically modes 1-3 at 75 Hz), and intermediate order modes whose waveguide invariant is near-zero (often around mode 20 at 75 Hz). Information loss is quantified by the bit error rate (BER) of a recovered binary phase-coded signal. With fixed receiver depths, low BERs (less than 1%) are achieved at ranges up to 400 km with three hydrophones for mode 1 with 90% probability and with 34 hydrophones for mode 20 with 80% probability. With optimal receiver depths, depending on propagation range, only a few, sometimes only two, hydrophones are often sufficient for low BERs, even with intermediate mode numbers. Full modal resolution is unnecessary to achieve low BERs. Thus, a flexible receiver array of autonomous vehicles can outperform a cabled array.

  9. Delay-Dependent Response in Weakly Electric Fish under Closed-Loop Pulse Stimulation.

    Science.gov (United States)

    Forlim, Caroline Garcia; Pinto, Reynaldo Daniel; Varona, Pablo; Rodríguez, Francisco B

    2015-01-01

    In this paper, we apply a real time activity-dependent protocol to study how freely swimming weakly electric fish produce and process the timing of their own electric signals. Specifically, we address this study in the elephant fish, Gnathonemus petersii, an animal that uses weak discharges to locate obstacles or food while navigating, as well as for electro-communication with conspecifics. To investigate how the inter pulse intervals vary in response to external stimuli, we compare the response to a simple closed-loop stimulation protocol and the signals generated without electrical stimulation. The activity-dependent stimulation protocol explores different stimulus delivery delays relative to the fish's own electric discharges. We show that there is a critical time delay in this closed-loop interaction, as the largest changes in inter pulse intervals occur when the stimulation delay is below 100 ms. We also discuss the implications of these findings in the context of information processing in weakly electric fish.

  10. Weakly pulse-coupled oscillators, FM interactions, synchronization, and oscillatory associative memory.

    Science.gov (United States)

    Izhikevich, E M

    1999-01-01

    We study pulse-coupled neural networks that satisfy only two assumptions: each isolated neuron fires periodically, and the neurons are weakly connected. Each such network can be transformed by a piece-wise continuous change of variables into a phase model, whose synchronization behavior and oscillatory associative properties are easier to analyze and understand. Using the phase model, we can predict whether a given pulse-coupled network has oscillatory associative memory, or what minimal adjustments should be made so that it can acquire memory. In the search for such minimal adjustments we obtain a large class of simple pulse-coupled neural networks that can memorize and reproduce synchronized temporal patterns the same way a Hopfield network does with static patterns. The learning occurs via modification of synaptic weights and/or synaptic transmission delays.

  11. Observation of energy oscillation between strongly-coupled counter-propagating ultra-high Q whispering gallery modes.

    Science.gov (United States)

    Yoshiki, Wataru; Chen-Jinnai, Akitoshi; Tetsumoto, Tomohiro; Tanabe, Takasumi

    2015-11-30

    We report the first experimental observation of an energy oscillation between two coupled ultra-high Q whispering gallery modes in the time domain. Two counter-propagating whispering gallery modes in a silica toroid microcavity were employed for this purpose. The combination of a large coupling coefficient between the two modes and an ultra-high Q factor, which creates a large Γ value of > 10, results in a clear energy oscillation. Our measurement is based on a drop-port measurement technique, which enables us to observe the light energy in the two modes directly. The oscillation period measured in the time domain precisely matched that inferred from mode splitting in the frequency domain, and the measured results showed excellent agreement with results calculated with the developed numerical model.

  12. Comparison of all-optical co- and counter-propagating high-speed signal processing in SOA-based Mach-Zehnder interferometers

    DEFF Research Database (Denmark)

    Bischoff, Svend; Buxens, Alvaro; Fischer, S.

    2001-01-01

    The all-optical signal processing performance of a Mach-Zehnder interferometer (MZI) is investigated. Calculated switching windows are used to investigate and understand the physical mechanisms limiting the high speed performance. Especially, the co- and counter-propagating operation of the MZI i...

  13. Three- and four-class classification models for P-glycoprotein inhibitors using counter-propagation neural networks.

    Science.gov (United States)

    Thai, K-M; Huynh, N-T; Ngo, T-D; Mai, T-T; Nguyen, T-H; Tran, T-D

    2015-01-01

    P-glycoprotein (P-gp) is an ATP binding cassette (ABC) transporter that helps to protect several certain human organs from xenobiotic exposure. This efflux pump is also responsible for multi-drug resistance (MDR), an issue of the chemotherapy approach in the fight against cancer. Therefore, the discovery of P-gp inhibitors is considered one of the most popular strategies to reverse MDR in tumour cells and to improve therapeutic efficacy of commonly used cytotoxic drugs. Until now, several generations of P-gp inhibitors have been developed but they have largely failed in preclinical and clinical studies due to lack of selectivity, poor solubility and severe pharmacokinetic interactions. In this study, three models (SION, SIO, SIN) to classify specific 'true' P-gp inhibitors as well as three other models (CPBN, CPB1, CPN) to distinguish between P-gp inhibitors, CYP 3A inhibitors and co-inhibitors of these proteins with rather high accuracy values for the test set and the external set were generated based on counter-propagation neural networks (CPG-NN). Such three and four-class classification models helped provide more information about the bioactivities of compounds not only on one target (P-gp), but also on a combination of multiple targets (P-gp, CYP 3A).

  14. Robust modelling of acute toxicity towards fathead minnow (Pimephales promelas) using counter-propagation artificial neural networks and genetic algorithm.

    Science.gov (United States)

    Drgan, V; Župerl, Š; Vračko, M; Como, F; Novič, M

    2016-07-01

    Large worldwide use of chemicals has caused great concern about their possible adverse effects on human health, flora and fauna. Increased production of new chemicals has also increased demand for their risk assessment. Traditionally, results from animal tests have been used to assess toxicity of chemicals. However, such methods are ethically questionable since they involve killing and causing suffering of the test animals. Therefore, new in silico methods are being sought to replace the traditional in vivo and in vitro testing methods. In this article we report on one method that can be used to build robust models for the prediction of compounds' properties from their chemical structure. The method has been developed by combining a genetic algorithm, a counter-propagation artificial neural network and cross-validation. It has been tested using existing data on toxicity to fathead minnow (Pimephales promelas). The results show that the method may give reliable results for chemicals belonging to the applicability domain of the developed models. Therefore, it can aid the risk assessment of chemicals and consequently reduce demand for animal tests.

  15. 3D characterization of the forces in optical traps based on counter-propagation beams shaped by a spatial light modulator

    DEFF Research Database (Denmark)

    Kristensen, M. V.; Lindballe, T.; Kylling, A.

    2010-01-01

    An experimental characterization of the 3D forces, acting on a trapped polystyrene bead in a counter-propagating beam geometry, is reported. Using a single optical trap with a large working distance (in the BioPhotonics Workstation), we simultaneously measure the transverse and longitudinal...... trapping force constants. Two different methods were used: The Drag force method and the Equipartition method. We show that the counterpropagating beams traps are simple harmonic for small displacements. The force constants reveal a transverse asymmetry as - = 9.7 pN/µm and + = 11.3 pN/µm (at a total laser...... power of 2x35 mW) for displacements in opposite directions. The Equipartition method is limited by mechanical noise and is shown to be applicable only when the total laser power in a single 10 µm counter-propagating trap is below 2x20 mW....

  16. Mean-square angle-of-arrival difference between two counter-propagating spherical waves in the presence of atmospheric turbulence.

    Science.gov (United States)

    Chen, Chunyi; Yang, Huamin; Tong, Shoufeng; Lou, Yan

    2015-09-21

    The mean-square angle-of-arrival (AOA) difference between two counter-propagating spherical waves in atmospheric turbulence is theoretically formulated. Closed-form expressions for the path weighting functions are obtained. It is found that the diffraction and refraction effects of turbulent cells make negative and positive contributions to the mean-square AOA difference, respectively, and the turbulent cells located at the midpoint of the propagation path have no contributions to the mean-square AOA difference. If the mean-square AOA difference is separated into the refraction and diffraction parts, the refraction part always dominates the diffraction one, and the ratio of the diffraction part to the refraction one is never larger than 0.5 for any turbulence spectrum. Based on the expressions for the mean-square AOA difference, formulae for the correlation coefficient between the angles of arrival of two counter-propagating spherical waves in atmospheric turbulence are derived. Numerical calculations are carried out by considering that the turbulence spectrum has no path dependence. It is shown that the mean-square AOA difference always approximates to the variance of AOA fluctuations. It is found that the correlation coefficient between the angles of arrival in the x or y direction of two counter-propagating spherical waves ranges from 0.46 to 0.5, implying that the instantaneous angles of arrival of two counter-propagating spherical waves in atmospheric turbulence are far from being perfectly correlated even when the turbulence spectrum does not vary along the path.

  17. Phase-only laser control in the weak-field limit: Two-pulse control of IBr photofragmentation revisited

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Henriksen, Niels Engholm

    2016-01-01

    We demonstrate theoretically that laser-induced coherent quantum interference control of asymptotic states of dissociating molecules is possible, starting from a single vibrational eigenstate, after the interaction with two laser pulses-at a fixed time delay-both operating in the weak-field limit...

  18. Class 1 neural excitability, conventional synapses, weakly connected networks, and mathematical foundations of pulse-coupled models.

    Science.gov (United States)

    Izhikevich, E M

    1999-01-01

    Many scientists believe that all pulse-coupled neural networks are toy models that are far away from the biological reality. We show here, however, that a huge class of biophysically detailed and biologically plausible neural-network models can be transformed into a canonical pulse-coupled form by a piece-wise continuous, possibly noninvertible, change of variables. Such transformations exist when a network satisfies a number of conditions; e.g., it is weakly connected; the neurons are Class 1 excitable (i.e., they can generate action potentials with an arbitrary small frequency); and the synapses between neurons are conventional (i.e., axo-dendritic and axo-somatic). Thus, the difference between studying the pulse-coupled model and Hodgkin-Huxley-type neural networks is just a matter of a coordinate change. Therefore, any piece of information about the pulse-coupled model is valuable since it tells something about all weakly connected networks of Class 1 neurons. For example, we show that the pulse-coupled network of identical neurons does not synchronize in-phase. This confirms Ermentrout's result that weakly connected Class 1 neurons are difficult to synchronize, regardless of the equations that describe dynamics of each cell.

  19. Finite-key analysis for quantum key distribution with weak coherent pulses based on Bernoulli sampling

    Science.gov (United States)

    Kawakami, Shun; Sasaki, Toshihiko; Koashi, Masato

    2017-07-01

    An essential step in quantum key distribution is the estimation of parameters related to the leaked amount of information, which is usually done by sampling of the communication data. When the data size is finite, the final key rate depends on how the estimation process handles statistical fluctuations. Many of the present security analyses are based on the method with simple random sampling, where hypergeometric distribution or its known bounds are used for the estimation. Here we propose a concise method based on Bernoulli sampling, which is related to binomial distribution. Our method is suitable for the Bennett-Brassard 1984 (BB84) protocol with weak coherent pulses [C. H. Bennett and G. Brassard, Proceedings of the IEEE Conference on Computers, Systems and Signal Processing (IEEE, New York, 1984), Vol. 175], reducing the number of estimated parameters to achieve a higher key generation rate compared to the method with simple random sampling. We also apply the method to prove the security of the differential-quadrature-phase-shift (DQPS) protocol in the finite-key regime. The result indicates that the advantage of the DQPS protocol over the phase-encoding BB84 protocol in terms of the key rate, which was previously confirmed in the asymptotic regime, persists in the finite-key regime.

  20. Three- and two-dimensional simulations of counter-propagating shear experiments at high energy densities at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ping; Zhou, Ye, E-mail: yezhou@llnl.gov; MacLaren, Stephan A.; Huntington, Channing M.; Raman, Kumar S. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Doss, Forrest W.; Flippo, Kirk A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2015-11-15

    Three- and two-dimensional numerical studies have been carried out to simulate recent counter-propagating shear flow experiments on the National Ignition Facility. A multi-physics three-dimensional, time-dependent radiation hydrodynamics simulation code is used. Using a Reynolds Averaging Navier-Stokes model, we show that the evolution of the mixing layer width obtained from the simulations agrees well with that measured from the experiments. A sensitivity study is conducted to illustrate a 3D geometrical effect that could confuse the measurement at late times, if the energy drives from the two ends of the shock tube are asymmetric. Implications for future experiments are discussed.

  1. Laser-pulse-shape control of photofragmentation in the weak-field limit

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Dey, Diptesh; Henriksen, Niels Engholm

    2014-01-01

    We demonstrate theoretically that laser-induced coherent quantum interference control of asymptotic states of dissociating molecules is possible even in the (one-photon) weak-field limit starting from a single vibrational eigenstate. Thus, phase dependence in the interaction with a fixed energy...

  2. Phase-only shaped laser pulses in optimal control theory: Application to indirect photofragmentation dynamics in the weak-field limit

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Henriksen, Niels E.

    2012-01-01

    We implement phase-only shaped laser pulses within quantum optimal control theory for laser-molecule interaction. This approach is applied to the indirect photofragmentation dynamics of NaI in the weak-field limit. It is shown that optimized phase-modulated pulses with a fixed frequency distribut...

  3. Nuclear quadrupole spin dynamics: How weak RF pulses and double resonance cross-relaxation contribute to explosives detection

    Science.gov (United States)

    Prescott, David

    Nuclear quadrupole resonance (NQR) is a type of radio-frequency (rf) spectroscopy which can detect quadrupolar nuclei (I > 1/2), such as nitrogen, in crystalline solids. NQR spectroscopy is useful for the detection of the many types of explosives containing 14N, however it suffers from a low signal to noise ratio (SNR) particularly in samples with long spin-lattice relaxation times. To improve the SNR the nuclear quadrupole spin dynamics are exploited in two limiting cases: systems with long spin relaxation times and systems where the excitation power is limited. The former is addressed through double resonance effects and the latter through spin echoes created by weak rf pulses. The double resonance effect occurs in samples that also contain a second faster relaxing nuclear species, such as 1H in ammonium nitrate. In this sample an 1H-14N double resonance can be created between the species that improves the SNR. While the focus is on the common case of solids containing both nitrogen and hydrogen, the theory is generally applicable to solids containing spin-1 and spin-1/2 nuclei. A model of this system is developed that treats the motionally averaged secular dipolar Hamiltonian as a perturbation of the combined quadrupole and Zeeman Hamiltonians. This model reveals three types of double resonance conditions, involving static and rf fields, and predicts expressions for the cross-relaxation rate (Wd) between the two species. Using this cross-relaxation rate, in addition to the hydrogen and nitrogen autorelaxation rates, expressions governing the relaxation back to equilibrium in a spin-1/2 and spin-1 system are determined. The three different types of double resonance conditions are created experimentally; one of them for the first time in any system and another for the first time in a solid. Under these double resonance conditions, the increase in Wd and improvements in SNR are explored both theoretically and experimentally using ammonium nitrate. The second effect

  4. Cell Proliferation, Migration, and Neurogenesis in the Adult Brain of the Pulse Type Weakly Electric Fish, Gymnotus omarorum

    Science.gov (United States)

    Olivera-Pasilio, Valentina; Lasserre, Moira; Castelló, María E.

    2017-01-01

    Adult neurogenesis, an essential mechanism of brain plasticity, enables brain development along postnatal life, constant addition of new neurons, neuronal turnover, and/or regeneration. It is amply distributed but negatively modulated during development and along evolution. Widespread cell proliferation, high neurogenic, and regenerative capacities are considered characteristics of teleost brains during adulthood. These anamniotes are promising models to depict factors that modulate cell proliferation, migration, and neurogenesis, and might be intervened to promote brain plasticity in mammals. Nevertheless, the migration path of derived cells to their final destination was not studied in various teleosts, including most weakly electric fish. In this group adult brain morphology is attributed to sensory specialization, involving the concerted evolution of peripheral electroreceptors and electric organs, encompassed by the evolution of neural networks involved in electrosensory information processing. In wave type gymnotids adult brain morphology is proposed to result from lifelong region specific cell proliferation and neurogenesis. Consistently, pulse type weakly electric gymnotids and mormyrids show widespread distribution of proliferation zones that persists in adulthood, but their neurogenic potential is still unknown. Here we studied the migration process and differentiation of newborn cells into the neuronal phenotype in the pulse type gymnotid Gymnotus omarorum. Pulse labeling of S-phase cells with 5-Chloro-2′-deoxyuridine thymidine followed by 1 to 180 day survivals evidenced long distance migration of newborn cells from the rostralmost telencephalic ventricle to the olfactory bulb, and between layers of all cerebellar divisions. Shorter migration appeared in the tectum opticum and torus semicircularis. In many brain regions, derived cells expressed early neuronal markers doublecortin (chase: 1–30 days) and HuC/HuD (chase: 7–180 days). Some newborn

  5. Cell Proliferation, Migration, and Neurogenesis in the Adult Brain of the Pulse Type Weakly Electric Fish, Gymnotus omarorum

    Directory of Open Access Journals (Sweden)

    Valentina Olivera-Pasilio

    2017-08-01

    Full Text Available Adult neurogenesis, an essential mechanism of brain plasticity, enables brain development along postnatal life, constant addition of new neurons, neuronal turnover, and/or regeneration. It is amply distributed but negatively modulated during development and along evolution. Widespread cell proliferation, high neurogenic, and regenerative capacities are considered characteristics of teleost brains during adulthood. These anamniotes are promising models to depict factors that modulate cell proliferation, migration, and neurogenesis, and might be intervened to promote brain plasticity in mammals. Nevertheless, the migration path of derived cells to their final destination was not studied in various teleosts, including most weakly electric fish. In this group adult brain morphology is attributed to sensory specialization, involving the concerted evolution of peripheral electroreceptors and electric organs, encompassed by the evolution of neural networks involved in electrosensory information processing. In wave type gymnotids adult brain morphology is proposed to result from lifelong region specific cell proliferation and neurogenesis. Consistently, pulse type weakly electric gymnotids and mormyrids show widespread distribution of proliferation zones that persists in adulthood, but their neurogenic potential is still unknown. Here we studied the migration process and differentiation of newborn cells into the neuronal phenotype in the pulse type gymnotid Gymnotus omarorum. Pulse labeling of S-phase cells with 5-Chloro-2′-deoxyuridine thymidine followed by 1 to 180 day survivals evidenced long distance migration of newborn cells from the rostralmost telencephalic ventricle to the olfactory bulb, and between layers of all cerebellar divisions. Shorter migration appeared in the tectum opticum and torus semicircularis. In many brain regions, derived cells expressed early neuronal markers doublecortin (chase: 1–30 days and HuC/HuD (chase: 7–180 days

  6. Evaluating the applicability domain in the case of classification predictive models for carcinogenicity based on the counter propagation artificial neural network.

    Science.gov (United States)

    Fjodorova, Natalja; Novič, Marjana; Roncaglioni, Alessandra; Benfenati, Emilio

    2011-12-01

    The applicability domain (AD) of models developed for regulatory use has attached great attention recently. The AD of quantitative structure-activity relationship (QSAR) models is the response and chemical structure space in which the model makes predictions with a given reliability. The evaluation of AD of regressions QSAR models for congeneric sets of chemicals can be find in many papers and books while the issue about metrics for the evaluation of an AD for the non-linear models (like neural networks) for the diverse set of chemicals represents the new field of investigations in QSAR studies. The scientific society is standing before the challenge to find out reliable way for the evaluation of an AD of non linear models. The new metrics for the evaluation of the AD of the counter propagation artificial neural network (CP ANN) models are discussed in the article: the Euclidean distances between an object (molecule) and the corresponding excited neuron of the neural network and between an object (molecule) and the representative object (vector of average values of descriptors). The investigation of the training and test sets chemicals coverage in the descriptors space was made with the respect to false predicted chemicals. The leverage approach was used to compare non linear (CP ANN) models with linear ones.

  7. Assessment of applicability domain for multivariate counter-propagation artificial neural network predictive models by minimum euclidean distance space analysis: a case study.

    Science.gov (United States)

    Minovski, Nikola; Župerl, Špela; Drgan, Viktor; Novič, Marjana

    2013-01-08

    Alongside the validation, the concept of applicability domain (AD) is probably one of the most important aspects which determine the quality as well as reliability of the established quantitative structure-activity relationship (QSAR) models. To date, a variety of approaches for AD estimation have been devised which can be applied to particular type of QSAR models and their practical utilization is extensively elaborated in the literature. The present study introduces a novel, simple, and effective distance-based method for estimation of the AD in case of developed and validated predictive counter-propagation artificial neural network (CP ANN) models through a proficient exploitation of the euclidean distance (ED) metric in the structure-representation vector space. The performance of the method was evaluated and explained in a case study by using a pre-built and validated CP ANN model for prediction of the transport activity of the transmembrane protein bilitranslocase for a diverse set of compounds. The method was tested on two more datasets in order to confirm its performance for evaluation of the applicability domain in CP ANN models. The chemical compounds determined as potential outliers, i.e., outside of the CP ANN model AD, were confirmed in a comparative AD assessment by using the leverage approach. Moreover, the method offers a graphical depiction of the AD for fast and simple determination of the extreme points. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Classification of sphingosine kinase inhibitors using counter propagation artificial neural networks: A systematic route for designing selective SphK inhibitors.

    Science.gov (United States)

    Neiband, M S; Mani-Varnosfaderani, A; Benvidi, A

    2017-02-01

    Accurate and robust classification models for describing and predicting the activity of 330 chemicals that are sphingosine kinase 1 (SphK1) and/or sphingosine kinase 2 (SphK2) inhibitors were derived. The classification models developed in this work assist in finding selective subspaces in chemical space occupied by particular groups of SphK inhibitors. A combination of a genetic algorithm (GA) and a counter propagation artificial neural network (CPANN) was utilized to select the most efficient subsets of the molecular descriptors. The optimized models in this work reasonably separate active inhibitors of SphK1 from active SphK2 inhibitors. Generally, the CPANN models in this work were used to classify the compounds according to their therapeutic targets and activities. The simplicity of the chosen descriptors and their relative importance sheds some light on the structural features necessary to induce selective inhibitory activity to the studied molecules. The areas under the receiver operating characteristic (ROC) curves for the GA-CPANN models in this work were 0.934 and 0.922 for active SphK1 and SphK2 inhibitors, respectively. Generally, the results in this work suggest some important molecular features and pharmacophores that could help medicinal chemists develop selective and potent SphK inhibitors.

  9. On the mechanism of the picosecond switching phenomenon in devices based on the open discharge with counter-propagating electron beams

    Science.gov (United States)

    Bokhan, P. A.; Gugin, P. P.; Lavrukhin, M. A.; Zakrevsky, Dm E.

    2016-06-01

    The subnanosecond breakdown stage in the kivotron, a switching device with counter-propagating electron beams based on the open discharge in helium, was experimentally studied. It was shown that the fast discharge stage arises when the discharge self-sustaining regime is ensured by the photoelectron emission from of the cathodes due to the resonant radiation, emitted by fast helium atoms that have large Doppler shifts with respect to the line center; as a result, the emitted radiation reaches the cathodes without imprisonment by the helium gas. Since the cross-section for the excitation of a helium atom with another (fast) helium atom increases rapidly with the energy of the fast atom, the duration of the breakdown stage strongly depends on the working voltage. The transient characteristic is modulated by microwave oscillations of ~4.4 GHz frequency generated during the discharge of kivotron self-capacitance through its self-induction. An increase in working pressure leads to suppression of oscillations. A switching time of 80 ps was achieved in a discharge circuit loaded to a resistance R L  ⩾  50 Ω. On decreasing the value of R L down to 10 Ω, the switching time increases to about 100 ps at 1.5 kA current. A minimum switching time that can be achieved via kivotron design optimization is estimated to be about 35 ps.

  10. Scattering of relativistic electron beam by two counter-propagating laser pulses: A new approach to Raman X-ray amplification

    Directory of Open Access Journals (Sweden)

    Andriyash I.A.

    2013-11-01

    Full Text Available We present a detailed study of the properties of electron beam injected and trapped in an high intensity optical lattice. By using the hydrodynamic and kinetic approaches, we identified the beam trapping conditions, the high-frequency longitudinal beam eigenmodes and their dependence on the electron angular and energy spread. The coupling of these beam eigenmodes to the laser waves is also considered. This corresponds to the convective parametric instability: a stimulated scattering of two laser beams creating the optical lattice on the trapped electron beam mode. The amplification coefficients for the up-scattered Raman modes propagating parallel to the electron beam are calculated and their dependence on the beam characteristics is analyzed.

  11. Vortex states near absolute zero in a weak-pinning amorphous Mo x Ge1-x film probed by pulsed mode-locking resonance

    Science.gov (United States)

    Sohara, N.; Ochi, A.; Murakami, E.; Ienaga, K.; Kaneko, S.; Kokubo, N.; Okuma, S.

    2017-07-01

    We have developed measurements of the mode-locking (ML) resonance with pulsed currents, which generates much less heat than the conventional one with continuous currents. Here, we present the experimental details of the pulsed ML measurement. Using this technique, we have succeeded in determining the dynamic melting field of a driven vortex lattice for a weak-pinning thick amorphous Mo x Ge1-x film down to 0.05 K. We construct an ideal vortex phase diagram in the absence of pinning near zero temperature as a function of magnetic field.

  12. Measurement of the dynamic response of low-gain solid-state photodetector under weak pulse illumination

    CERN Document Server

    Clément, D; Morel, Christian

    2000-01-01

    This paper presents the development of a Tunable Light Pulse Generator built to measure the quantum efficiency of photodetectors under continuous or pulsed (20 ns FWHM) illumination as a function of wavelength in the Visible-UV region. For this purpose, a miniature Hamamatsu R5600U-04 PMT with low cathode resistivity can be used as reference detector. Dedicated electronics was developed in order to measure simultaneously the cathode and anode currents. This should allow to determine precisely the gain as a function of the high voltage applied to the PMT. Preliminary measurements using the TLPG do not demonstrate significant differences between the dynamic (approx 10 000 photons) and DC responses of PIN photodiodes down to 300 nm.

  13. Two-frequency mutual coherence function for Gaussian-beam pulses propagating along a horizontal path in weak anisotropic atmospheric turbulence.

    Science.gov (United States)

    Chen, Chunyi; Yang, Huamin; Tong, Shoufeng; Lou, Yan

    2015-06-20

    A theoretical formulation of the spherical-wave two-frequency mutual coherence function (MCF) for a propagation path characterized by a complex ABCD matrix with anisotropic atmospheric turbulence existing somewhere is developed. A specialization of this formulation leads to an expression for the two-frequency MCF of an equivalent pulsed Gaussian beam propagating in weak anisotropic atmospheric turbulence along a horizontal line-of-sight path; relevant closed-form analytical solutions under both near- and far-field conditions are obtained. The small- and large-scale solutions for both the plane- and spherical-wave spatial-coherence radii in either horizontal or vertical direction are derived. Analysis shows that the formula for the on-axis two-frequency MCF of a pulsed Gaussian beam under the weak-turbulence condition in both the near- and far-field regions is distinguished from that applicable in the strong-turbulence limit only by whether the turbulence-induced beam broadening can be thought of as negligible. Under both the near- and far-field conditions, the turbulence-induced increment of the mean-square temporal-pulse half-width is proportional to the effective anisotropy factor of turbulence. The MCF becomes statistically anisotropic due to the anisotropy of turbulence. For the spatial coherence radius of either a plane or spherical wave propagating along a horizontal line-of-sight path in anisotropic atmospheric turbulence, the corresponding small-scale solution is proportional to that for the plane-wave spatial-coherence radius in the isotropic-turbulence case with a proportionality coefficient depending only on the effective anisotropy factor of turbulence. The corresponding large-scale solution is proportional to that for the plane-wave spatial-coherence radius in the isotropic-turbulence case with a proportionality coefficient that depends on both the effective anisotropy factor and spectral index of turbulence.

  14. Two-photon interference of weak coherent laser pulses recalled from separate solid-state quantum memories.

    Science.gov (United States)

    Jin, Jeongwan; Slater, Joshua A; Saglamyurek, Erhan; Sinclair, Neil; George, Mathew; Ricken, Raimund; Oblak, Daniel; Sohler, Wolfgang; Tittel, Wolfgang

    2013-01-01

    Quantum memories allowing reversible transfer of quantum states between light and matter are central to quantum repeaters, quantum networks and linear optics quantum computing. Significant progress regarding the faithful transfer of quantum information has been reported in recent years. However, none of these demonstrations confirm that the re-emitted photons remain suitable for two-photon interference measurements, such as C-NOT gates and Bell-state measurements, which constitute another key ingredient for all aforementioned applications. Here, using pairs of laser pulses at the single-photon level, we demonstrate two-photon interference and Bell-state measurements after either none, one or both pulses have been reversibly mapped to separate thulium-doped lithium niobate waveguides. As the interference is always near the theoretical maximum, we conclude that our solid-state quantum memories, in addition to faithfully mapping quantum information, also preserve the entire photonic wavefunction. Hence, our memories are generally suitable for future applications of quantum information processing that require two-photon interference.

  15. Two-photon interference of weak coherent laser pulses recalled from separate solid-state quantum memories

    Science.gov (United States)

    Jin, Jeongwan; Slater, Joshua A.; Saglamyurek, Erhan; Sinclair, Neil; George, Mathew; Ricken, Raimund; Oblak, Daniel; Sohler, Wolfgang; Tittel, Wolfgang

    2013-08-01

    Quantum memories allowing reversible transfer of quantum states between light and matter are central to quantum repeaters, quantum networks and linear optics quantum computing. Significant progress regarding the faithful transfer of quantum information has been reported in recent years. However, none of these demonstrations confirm that the re-emitted photons remain suitable for two-photon interference measurements, such as C-NOT gates and Bell-state measurements, which constitute another key ingredient for all aforementioned applications. Here, using pairs of laser pulses at the single-photon level, we demonstrate two-photon interference and Bell-state measurements after either none, one or both pulses have been reversibly mapped to separate thulium-doped lithium niobate waveguides. As the interference is always near the theoretical maximum, we conclude that our solid-state quantum memories, in addition to faithfully mapping quantum information, also preserve the entire photonic wavefunction. Hence, our memories are generally suitable for future applications of quantum information processing that require two-photon interference.

  16. High power sub-200fs pulse generation from a colliding pulse modelocked VECSEL

    Science.gov (United States)

    Laurain, Alexandre; Marah, Declan; Rockmore, Robert; McInerney, John G.; Hader, Jorg; Ruiz Perez, Antje; Koch, Stephan W.; Stolz, Wolfgang; Moloney, Jerome V.

    2017-02-01

    We present a passive and robust mode-locking scheme for a Vertical External Cavity Surface Emitting Laser (VECSEL).We placed the semiconductor gain medium and the semiconductor saturable absorber mirror (SESAM) strategically in a ring cavity to provide a stable colliding pulse operation. With this cavity geometry, the two counter propagating pulses synchronize on the SESAM to saturate the absorber together. This minimizes the energy lost and creates a transient carrier grating due to the interference of the two beams. The interaction of the two counter-propagating pulses in the SESAM is shown to extend the range of the modelocking regime and to enable higher output power when compared to the conventional VECSEL cavity geometry. In this configuration, we demonstrate a pulse duration of 195fs with an average power of 225mW per output beam at a repetition rate of 2.2GHz, giving a peak power of 460W per beam. The remarkable robustness of the modelocking regime is discussed and a rigorous pulse characterization is presented.

  17. Influence of a Weak Field of Pulsed DC Electricity on the Behavior and Incidence of Injury in Adult Steelhead and Pacific Lamprey, Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Mesa, Matthew

    2009-02-13

    electrofishing operations typically use high voltage and amperage settings and a variety of waveforms, pulse widths (PW), and pulse frequencies (PF), depending on conditions and target species. For example, when backpack electrofishing for trout in a small stream, one might use settings such as 500 V pulsed DC, a PW of 1 ms, and a PF of 60 Hz. In contrast, the electrical barrier proposed by SRI will produce electrical conditions significantly lower than those used in electrofishing, particularly for PW and PF (e.g., PW ranging from 300-1,000 {micro}s and PF from 2-3 Hz). Further, voltage gradients (in V/cm) are predicted to be lower in the electric barrier than those produced during typical electrofishing. Although the relatively weak, pulsed DC electric fields to be produced by the barrier may be effective at deterring pinnipeds, little, if anything, is known about the effects of such low intensity electrical fields on fish behavior. For this research, we evaluated the effects of weak, pulsed DC electric currents on the behavior of adult steelhead and Pacific lamprey and the incidence of injury in steelhead only. In a series of laboratory experiments, we: (1) documented the rate of passage of fish over miniature, prototype electric barriers when they were on and off; (2) determined some electric thresholds beyond which fish would not pass over the barrier; and (3) assessed the incidence and severity of injury in steelhead exposed to relatively severe electrical conditions. The results of this study should be useful for making decisions about whether to install electrical barriers in the lower Columbia River, or elsewhere, to reduce predation on upstream migrating salmonids and other fishes by marine pinnipeds.

  18. Prediction of aqueous solubility of drug-like molecules using a novel algorithm for automatic adjustment of relative importance of descriptors implemented in counter-propagation artificial neural networks.

    Science.gov (United States)

    Erić, Slavica; Kalinić, Marko; Popović, Aleksandar; Zloh, Mire; Kuzmanovski, Igor

    2012-11-01

    In this work, we present a novel approach for the development of models for prediction of aqueous solubility, based on the implementation of an algorithm for the automatic adjustment of descriptor's relative importance (AARI) in counter-propagation artificial neural networks (CPANN). Using this approach, the interpretability of the models based on artificial neural networks, which are traditionally considered as "black box" models, was significantly improved. For the development of the model, a data set consisting of 374 diverse drug-like molecules, divided into training (n=280) and test (n=94) sets using self-organizing maps, was used. Heuristic method was applied in preselecting a small number of the most significant descriptors to serve as inputs for CPANN training. The performances of the final model based on 7 descriptors for prediction of solubility were satisfactory for both training (RMSEP(train)=0.668) and test set (RMSEP(test)=0.679). The model was found to be a highly interpretable in terms of solubility, as well as rationalizing structural features that could have an impact on the solubility of the compounds investigated. Therefore, the proposed approach can significantly enhance model usability by giving guidance for structural modifications of compounds with the aim of improving solubility in the early phase of drug discovery. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Harmonic generation enhancement due to interaction of few-cycle light pulses in nonlinear dielectric coating on a mirror

    Science.gov (United States)

    Buyanovskaya, Elizaveta M.; Kniazev, Mikhail A.; Kozlov, Sergei A.; Sukhorukov, Andrey A.

    2017-11-01

    We theoretically investigate reflection of a few-cycle light pulse from a mirror with nonlinear dielectric coating. We employ a nonlinear equation that describes spatiotemporal evolution of a few-cycle light pulse with a broad spectrum that lies in the transparency range of nonlinear dielectric media. This model is formulated directly for the electric field without slowly varying amplitude approximation. Analytical and numerical analysis shows that counter-propagating wave interactions in thin films can strongly enhance or suppress third harmonic generation of the central frequency, whereas this effect is neglected in the framework of slowly varying amplitude approximation.

  20. Controlling Charge and Current Neutralization of an Ion Beam Pulse in a Background Plasma by Application of a Solenoidal Magnetic Field I: Weak Magnetic Field Limit

    Energy Technology Data Exchange (ETDEWEB)

    Kaganovich, I. D., Startsev, E. A., Sefkow, A. B., Davidson, R. C.

    2008-10-10

    Propagation of an intense charged particle beam pulse through a background plasma is a common problem in astrophysics and plasma applications. The plasma can effectively neutralize the charge and current of the beam pulse, and thus provides a convenient medium for beam transport. The application of a small solenoidal magnetic field can drastically change the self-magnetic and self- electric fields of the beam pulse, thus allowing effective control of the beam transport through the background plasma. An analytic model is developed to describe the self-magnetic field of a finite- length ion beam pulse propagating in a cold background plasma in a solenoidal magnetic field. The analytic studies show that the solenoidal magnetic field starts to infuence the self-electric and self-magnetic fields when ωce > ωpeβb, where ωce = eβ/mec is the electron gyrofrequency, ωpe is the electron plasma frequency, and βb = Vb/c is the ion beam velocity relative to the speed of light. This condition typically holds for relatively small magnetic fields (about 100G). Analytical formulas are derived for the effective radial force acting on the beam ions, which can be used to minimize beam pinching. The results of analytic theory have been verified by comparison with the simulation results obtained from two particle-in-cell codes, which show good agreement.

  1. Spatially resolved analysis of Kα x-ray emission from plasmas induced by a femtosecond weakly relativistic laser pulse at various polarizations.

    Science.gov (United States)

    Cristoforetti, G; Anania, M P; Faenov, A Ya; Giulietti, A; Giulietti, D; Hansen, S B; Koester, P; Labate, L; Levato, T; Pikuz, T A; Gizzi, L A

    2013-02-01

    Spatially resolved K-shell spectroscopy is used here to investigate the interaction of an ultrashort laser pulse (λ=800 nm, τ=40 fs) with a Ti foil under intense irradiation (Iλ(2)=2×10(18)Wμm(2)cm(-2)) and the following fast electron generation and transport into the target. The effect of laser pulse polarization (p, s, and circular) on the Kα yield and line shape is probed. The radial structure of intensity and width of the lines, obtained by a discretized Abel deconvolution algorithm, suggests an annular distribution of both the hot electron propagation into the target and the target temperature. An accurate modeling of Kα line shapes was performed, revealing temperature gradients, going from a few eV up to 15-20 eV, depending on the pulse polarization. Results are discussed in terms of mechanisms of hot electron generation and of their transport through the preplasma in front of the target.

  2. Pulsed-induced electromagnetically induced transparency in the acetylene-filled hollow-core fibers

    Science.gov (United States)

    Rodríguez, Nayeli Casillas; Stepanov, Serguei; Miramontes, Manuel Ocegueda; Hernández, Eliseo Hernández

    2017-06-01

    Experimental results on pulsed excitation of electromagnetically induced transparency (EIT) in the acetylene-filled hollow-core photonic crystal fiber (HC-PCF) at pressures 0.1-0.4 Torr are reported. The EIT was observed both in Λ and V interaction configurations with the continuous probe wave tuned to R9 (1520.08 nm) acetylene absorption line and with the control pulses tuned to P11 (1531.58 nm) and P9 (1530.37 nm) lines, respectively. The utilized control pulses were of up to 40 ns duration with <2.5 ns fronts and with maximum input power 1 W. The maximum modulation depth of the initial probe wave absorption via EIT was up to 40 and 15% for the co- and counter-propagation of the probe and control waves, respectively, and importance of the waves polarization matching was demonstrated. For a qualitative explanation of reduction in the counter-propagation EIT efficiency a simple model of the accelerated mismatch of the two-frequency EIT resonance with deviation of the molecule thermal velocity from the resonance value was utilized. It was shown experimentally that the EIT efficiencies in both configurations do not depend on the longitudinal velocity of the molecules. The characteristic relaxation time of the of the EIT response was found to be about 9 ns, i.e., is close to the relaxation times T 1,2 of the acetylene molecules under the utilized experimental conditions.

  3. Synergistic effect of EMF-BEMER-type pulsed weak electromagnetic field and HPMA-bound doxorubicin on mouse EL4 T-cell lymphoma.

    Science.gov (United States)

    Říhová, Blanka; Etrych, Tomáš; Šírová, Milada; Tomala, Jakub; Ulbrich, Karel; Kovář, Marek

    2011-12-01

    We have investigated the effects of low-frequency pulsed electromagnetic field (LF-EMF) produced by BEMER device on experimental mouse T-cell lymphoma EL4 growing on conventional and/or athymic (nude) mice. Exposure to EMF-BEMER slowed down the growth of tumor mass and prolonged the survival of experimental animals. The effect was more pronounced in immuno-compromised nude mice compared to conventional ones. Acceleration of tumor growth was never observed. No measurable levels of Hsp 70 or increased levels of specific anti-EL4 antibodies were detected in the serum taken from experimental mice before and at different intervals during the experiment, i.e. before solid tumor appeared, at the time of its aggressive growth, and at the terminal stage of the disease. A significant synergizing antitumor effect was seen when EL4 tumor-bearing mice were simultaneously exposed to EMF-BEMER and treated with suboptimal dose of synthetic HPMA copolymer-based doxorubicin, DOX(HYD)-HPMA. Such a combination may be especially useful for heavily treated patients suffering from advanced tumor and requiring additional aggressive chemotherapy which, however, at that time could represent almost life-threatening way of medication.

  4. Chirped-Pulse Fourier-Transform Microwave Spectroscopy of the Prototypical C-H\\cdotsπ Interaction: the BENZENE\\cdotsACETYLENE Weakly Bound Dimer

    Science.gov (United States)

    Ulrich, Nathan; Seifert, Nathan A.; Dorris, Rachel E.; Peebles, Rebecca A.; Peebles, Sean A.; Pate, Brooks

    2014-06-01

    The rotational spectrum of the CH\\cdotsπ bonded complex between benzene and acetylene has been measured in the 6-20 GHz range using chirped-pulse Fourier-transform microwave spectroscopy. The spectra for the normal isotopologue, three unique 13C substituted species, and the d_1-benzene\\cdotsHCCH species have allowed determination of the dimer structure. The spectrum is that of a symmetric top, with effective C6v symmetry, and a CH\\cdotsπ distance of 2.4921(1) Å. The dipole moment has been measured using the Stark effect, and is 0.438(11) D. In addition to the ground state spectrum, three additional sets of transitions corresponding to similar rotational constants have been observed, likely due to excitation of the three low energy intermolecular vibrational modes of the dimer. Analysis of these excited state transitions is in progress. Comparison of the binding energy and structure of the benzene\\cdotsHCCH dimer with other H\\cdotsπ complexes will be presented.

  5. Colliding pulse mode-locked VECSEL

    Science.gov (United States)

    Marah, Declan; Laurain, Alexandre; Stolz, Wolfgang; Koch, Stephan; Ruiz Perez, Antje; McInerney, John; Moloney, Jerome

    2016-03-01

    Recent development of high power femtosecond pulse modelocked VECSEL with gigahertz pulse repetition rates sparked an increased interest from the scientific community due to the broad field of applications for such sources, such as frequency metrology, high-speed optical communication systems or high-resolution optical sampling. To the best of our knowledge, we report for the first time a colliding pulse modelocked VECSEL, where the VECSEL gain medium and a semiconductor saturable absorber (SESAM) are placed inside a ring cavity. This cavity geometry provides both a practical and an efficient way to get optimum performance from a modelocked laser system. The two counter propagating pulses in our ring cavity synchronize in the SESAM because the minimum energy is lost when they saturate the absorber together. This stronger saturation of the absorber increases the stability of the modelocking and reduces the overall losses of the laser for a given intra-cavity fluence, leading to a lower modelocking threshold. This also allows the generation of fundamental modelocking at a relatively low repetition rate (pulse repetition rate of 1GHz and a pulse duration ranging from 1ps to 3ps. The emitted spectrum was centered at 1007nm with a FWHM of 3.1nm, suggesting that shorter pulses can be obtained with adequate dispersion compensation. The laser characteristics such as the pulse duration and stability are studied in detail.

  6. A nonlinear plasma retroreflector for single pulse Compton backscattering

    CERN Document Server

    Palastro, J P; Gordon, D; Hafizi, B; Helle, M; Penano, J; Ting, A

    2014-01-01

    Compton scattered x-rays can be generated using a configuration consisting of a single, ultra-intense laser pulse, and a shaped gas target. The gas target incorporates a hydrodynamically formed density spike, which nonlinearly scatters the incident pump radiation, to produce a counter-propagating electromagnetic wiggler. This self-generated wiggler field Compton scatters from electrons accelerated in the laser wakefield of the pump radiation. The nonlinear scattering mechanism in the density spike is examined theoretically and numerically in order to optimize the Compton scattered radiation. It is found that narrow-band x-rays are produced by moderate intensity pump radiation incident on the quarter-critical surface of the density spike, while high fluence, broadband x-rays are produced by high intensity pump radiation reflected near the critical surface.

  7. Weak relativity

    CERN Document Server

    Selleri, Franco

    2015-01-01

    Weak Relativity is an equivalent theory to Special Relativity according to Reichenbach’s definition, where the parameter epsilon equals to 0. It formulates a Neo-Lorentzian approach by replacing the Lorentz transformations with a new set named “Inertial Transformations”, thus explaining the Sagnac effect, the twin paradox and the trip from the future to the past in an easy and elegant way. The cosmic microwave background is suggested as a possible privileged reference system. Most importantly, being a theory based on experimental proofs, rather than mutual consensus, it offers a physical description of reality independent of the human observation.

  8. Experimental quantum fingerprinting with weak coherent pulses

    Science.gov (United States)

    Xu, Feihu; Arrazola, Juan Miguel; Wei, Kejin; Wang, Wenyuan; Palacios-Avila, Pablo; Feng, Chen; Sajeed, Shihan; Lütkenhaus, Norbert; Lo, Hoi-Kwong

    2015-01-01

    Quantum communication holds the promise of creating disruptive technologies that will play an essential role in future communication networks. For example, the study of quantum communication complexity has shown that quantum communication allows exponential reductions in the information that must be transmitted to solve distributed computational tasks. Recently, protocols that realize this advantage using optical implementations have been proposed. Here we report a proof-of-concept experimental demonstration of a quantum fingerprinting system that is capable of transmitting less information than the best-known classical protocol. Our implementation is based on a modified version of a commercial quantum key distribution system using off-the-shelf optical components over telecom wavelengths, and is practical for messages as large as 100 Mbits, even in the presence of experimental imperfections. Our results provide a first step in the development of experimental quantum communication complexity. PMID:26515586

  9. Muscle Weakness

    Directory of Open Access Journals (Sweden)

    Ali Al Kaissi MD, MSc

    2017-01-01

    Full Text Available Marked ligamentous hyperlaxity and muscle weakness/wasting associated with awkward gait are the main deficits confused with the diagnosis of myopathy. Seven children (6 boys and 1 girl with an average age of 8 years were referred to our department because of diverse forms of skeletal abnormalities. No definitive diagnosis was made, and all underwent a series of sophisticated investigations in other institutes in favor of myopathy. We applied our methodology through the clinical and radiographic phenotypes followed by targeted genotypic confirmation. Three children (2 boys and 1 girl were compatible with the diagnosis of progressive pseudorheumatoid chondrodysplasia. The genetic mutation was correlated with the WISP 3 gene actively expressed by articular chondrocytes and located on chromosome 6. Klinefelter syndrome was the diagnosis in 2 boys. Karyotyping confirmed 47,XXY (aneuploidy of Klinefelter syndrome. And 2 boys were finally diagnosed with Morquio syndrome (MPS type IV A as both showed missense mutations in the N-acetylgalactosamine-sulfate sulfatase gene. Misdiagnosis can lead to the initiation of a long list of sophisticated investigations.

  10. Attosecond gamma-ray pulses via nonlinear Compton scattering in the radiation dominated regime

    CERN Document Server

    Li, Jian-Xing; Galow, Benjamin J; Keitel, Christoph H

    2015-01-01

    The interaction of a relativistic electron bunch with a counter-propagating tightly-focused laser beam is investigated for intensities when the dynamics is strongly affected by its own radiation. The Compton scattering spectra of gamma-radiation are evaluated employing a semiclassical description for the laser-driven electron dynamics and a quantum electrodynamical description for the photon emissions. We show for laser facilities under construction that gamma-ray bursts of few hundred attoseconds and dozens of megaelectronvolt photon energies may be detected in the near-backwards direction of the initial electron motion. Tight focussing of the laser beam and radiation reaction are demonstrated to be jointly responsible for such short gamma-ray bursts which are independent of both duration of electron bunch and laser pulse. Furthermore, the stochastic nature of the gamma-photon emission features signatures in the resulting gamma-ray comb in the case of the application of a multi-cycle laser pulse.

  11. Time-resolved measurements with intense ultrashort laser pulses: a 'molecular movie' in real time

    Science.gov (United States)

    Rudenko, A.; Ergler, Th; Feuerstein, B.; Zrost, K.; Schröter, C. D.; Moshammer, R.; Ullrich, J.

    2007-11-01

    We report on the high-resolution multidimensional real-time mapping of H2+ and D2+ nuclear wave packets performed employing time-resolved three-dimensional Coulomb explosion imaging with intense laser pulses. Exploiting a combination of a "reaction microscope" spectrometer and a pump-probe setup with two intense 6-7 fs laser pulses, we simultaneously visualize both vibrational and rotational motion of the molecule, and obtain a sequence of snapshots of the squared ro-vibrational wave function with time-step resolution of ~ 0.3 fs, allowing us to reconstruct a real-time movie of the ultrafast molecular motion. We observe fast dephasing, or 'collapse' of the vibrational wave packet and its subsequent revival, as well as signatures of rotational excitation. For D2+ we resolve also the fractional revivals resulting from the interference between the counter-propagating parts of the wave packet.

  12. Gauge-invariant theory of quasiparticle and condensate dynamics in response to terahertz optical pulses in superconducting semiconductor quantum wells. I. s -wave superconductivity in the weak spin-orbit coupling limit

    Science.gov (United States)

    Yu, T.; Wu, M. W.

    2017-10-01

    We investigate the quasiparticle and condensate dynamics in response to the terahertz optical pulses in the weak spin-orbit-coupled s -wave superconducting semiconductor quantum wells by using the gauge-invariant optical Bloch equations in the quasiparticle approximation. Specifically, in the Bloch equations, not only can the microscopic description for the quasiparticle dynamics be realized, but also the dynamics of the condensate is included, with the superfluid velocity and the effective chemical potential naturally incorporated. We reveal that the superfluid velocity itself can contribute to the pump of quasiparticles (pump effect), with its rate of change acting as the drive field to drive the quasiparticles (drive effect). We find that the oscillations of the Higgs mode with twice the frequency of the optical field are contributed dominantly by the drive effect but not the pump effect as long as the driven superconducting momentum is less than the Fermi momentum. This is in contrast to the conclusion from the Liouville or Bloch equations in the literature, in which the drive effect on the anomalous correlation is overlooked with only the pump effect considered. Furthermore, in the gauge-invariant optical Bloch equations, the charge neutrality condition is consistently considered based on the two-component model for the charge, in which the charge imbalance of quasiparticles can cause the fluctuation of the effective chemical potential for the condensate. It is predicted that during the optical process, the quasiparticle charge imbalance can be induced by both the pump and drive effects, leading to the fluctuation of the chemical potential. This fluctuation of the chemical potential is further demonstrated to directly lead to a relaxation channel for the charge imbalance even with the elastic scattering due to impurities. This is very different from the previous understanding that in the isotropic s -wave superconductivity, the impurity scattering cannot cause

  13. Beat wave injection of electrons into plasma waves using two interfering laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Fubiani, G.; Esarey, E.; Schroeder, C.B.; Leemans, W.P.

    2004-03-04

    An electron injector concept that uses a single injection laser pulse colliding with a pump laser pulse in a plasma is analyzed. The pump pulse generates a large amplitude laser wakefield (plasma wave). The counter propagating injection pulse collides with the pump laser pulse to generate a beat wave with a slow phase velocity. The ponderomotive force of the slow beat wave is responsible for injecting plasma electrons into the wakefield near the back of the pump pulse. Test particle simulations indicate that significant amounts of charge can be trapped and accelerated ({approx} 10 pC). For higher charge, beam loading limits the validity of the simulations. The accelerated bunches are ultrashort ({approx} 1 fs) with good beam quality (relative energy spread of a few percent at a mean energy of {approx} 10 MeV and a normalized rms emittance on the order 0.4 mm.mrad). The effects of interaction angle and polarization are also explored, e.g., efficient trapping can occur for near-collinear geometries. Beat wave injection using a single injection pulse has the advantages of simplicity, ease of experimental implementation, and requires modest laser intensity I {approx_equal} 8.8 x 10{sup 17} W/cm{sup 2}.

  14. Laser and Plasma Parameters for Laser Pulse Amplification by Stimulated Brillouin Backscattering in the Strong Coupling Regime

    Science.gov (United States)

    Gangolf, Thomas; Blecher, Marius; Bolanos, Simon; Lancia, Livia; Marques, Jean-Raphael; Cerchez, Mirela; Prasad, Rajendra; Aurand, Bastian; Loiseau, Pascal; Fuchs, Julien; Willi, Oswald

    2017-10-01

    In the ongoing quest for novel techniques to obtain ever higher laser powers, plasma amplification has drawn much attention, benefiting from the fact that a plasma can sustain much higher energy densities than a solid state amplifier. As a plasma process, Stimulated Brillouin Backscattering in the strong coupling regime (sc-SBS) can be used to transfer energy from one laser pulse (pump) to another (seed), by a nonlinear ion oscillation forced by the pump laser. Here, we report on experimental results on amplification by sc-SBS using the ARCTURUS Ti:Sapphire multi-beam laser system at the University of Duesseldorf, Germany. Counter-propagating in a supersonic Hydrogen gas jet target, an ultrashort seed pulse with a pulse duration between 30 and 160 fs and an energy between 1 and 12 mJ was amplified by a high-energy pump pulse (1.7 ps, 700 mJ). For some of the measurements, the gas was pre-ionized with a separate laser pulse (780 fs, 460 mJ). Preliminary analysis shows that the amplification was larger for the longer seed pulses, consistent with theoretical predictions.

  15. Coherent and dynamic beam splitting based on light storage in cold atoms

    OpenAIRE

    Kwang-Kyoon Park; Tian-Ming Zhao; Jong-Chan Lee; Young-Tak Chough; Yoon-Ho Kim

    2016-01-01

    We demonstrate a coherent and dynamic beam splitter based on light storage in cold atoms. An input weak laser pulse is first stored in a cold atom ensemble via electromagnetically-induced transparency (EIT). A set of counter-propagating control fields, applied at a later time, retrieves the stored pulse into two output spatial modes. The high visibility interference between the two output pulses clearly demonstrates that the beam splitting process is coherent. Furthermore, by manipulating the...

  16. Ultrashort vortex from a Gaussian pulse - An achromatic-interferometric approach.

    Science.gov (United States)

    Naik, Dinesh N; Saad, Nabil A; Rao, D Narayana; Viswanathan, Nirmal K

    2017-05-24

    The more than a century old Sagnac interferometer is put to first of its kind use to generate an achromatic single-charge vortex equivalent to a Laguerre-Gaussian beam possessing orbital angular momentum (OAM). The interference of counter-propagating polychromatic Gaussian beams of beam waist ωλ with correlated linear phase (ϕ 0  ≥ 0.025 λ) and lateral shear (y 0  ≥ 0.05 ωλ) in orthogonal directions is shown to create a vortex phase distribution around the null interference. Using a wavelength-tunable continuous-wave laser the entire range of visible wavelengths is shown to satisfy the condition for vortex generation to achieve a highly stable white-light vortex with excellent propagation integrity. The application capablitiy of the proposed scheme is demonstrated by generating ultrashort optical vortex pulses, its nonlinear frequency conversion and transforming them to vector pulses. We believe that our scheme for generating robust achromatic vortex (implemented with only mirrors and a beam-splitter) pulses in the femtosecond regime, with no conceivable spectral-temporal range and peak-power limitations, can have significant advantages for a variety of applications.

  17. Pulse on Pulse

    DEFF Research Database (Denmark)

    Schmidt, Ulrik; Carlson, Merete

    2012-01-01

    of the visitor’s beating heart to the blink of a fragile light bulb, thereby transforming each light bulb into a register of individual life. But at the same time the blinking light bulbs together produce a chaotically flickering light environment composed by various layers of repetitive rhythms, a vibrant...... and pulsating ‘room’. Hence, the visitors in Pulse Room are invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic ‘rhythm of life’) and instants of pure material processuality...... (flickering light bulbs; polyrhythmic layers). Taking our point of departure in a discussion of Gilles Deleuze’s concepts of modulation and signaletic material in relation to electronic media, we examine how the complex orchestration of pulsation between signification and material modulation produces...

  18. WEAK GORENSTEIN GLOBAL DIMENSION

    OpenAIRE

    Bennis, Driss

    2010-01-01

    In this paper, we investigate the weak Gorenstein global dimensions. We are mainly interested in studying the problem when the left and right weak Gorenstein global dimensions coincide. We first show, for GF-closed rings, that the left and right weak Gorenstein global dimensions are equal when they are finite. Then, we prove that the same equality holds for any two-sided coherent ring. We conclude the paper with some examples and a brief discussion of the scope and limits of our results.

  19. History of Weak Interactions

    Science.gov (United States)

    Lee, T. D.

    1970-07-01

    While the phenomenon of beta-decay was discovered near the end of the last century, the notion that the weak interaction forms a separate field of physical forces evolved rather gradually. This became clear only after the experimental discoveries of other weak reactions such as muon-decay, muon-capture, etc., and the theoretical observation that all these reactions can be described by approximately the same coupling constant, thus giving rise to the notion of a universal weak interaction. Only then did one slowly recognize that the weak interaction force forms an independent field, perhaps on the same footing as the gravitational force, the electromagnetic force, and the strong nuclear and sub-nuclear forces.

  20. Weak bond screening system

    Science.gov (United States)

    Chuang, S. Y.; Chang, F. H.; Bell, J. R.

    Consideration is given to the development of a weak bond screening system which is based on the utilization of a high power ultrasonic (HPU) technique. The instrumentation of the prototype bond strength screening system is described, and the adhesively bonded specimens used in the system developmental effort are detailed. Test results obtained from these specimens are presented in terms of bond strength and level of high power ultrasound irradiation. The following observations were made: (1) for Al/Al specimens, 2.6 sec of HPU irradiation will screen weak bond conditions due to improper preparation of bonding surfaces; (2) for composite/composite specimens, 2.0 sec of HPU irradiation will disrupt weak bonds due to under-cured conditions; (3) for Al honeycomb core with composite skin structure, 3.5 sec of HPU irradiation will disrupt weak bonds due to bad adhesive or oils contamination of bonding surfaces; and (4) for Nomex honeycomb with Al skin structure, 1.3 sec of HPU irradiation will disrupt weak bonds due to bad adhesive.

  1. Bagging Weak Predictors

    DEFF Research Database (Denmark)

    Lukas, Manuel; Hillebrand, Eric

    Relations between economic variables can often not be exploited for forecasting, suggesting that predictors are weak in the sense that estimation uncertainty is larger than bias from ignoring the relation. In this paper, we propose a novel bagging predictor designed for such weak predictor...... variables. The predictor is based on a test for finitesample predictive ability. Our predictor shrinks the OLS estimate not to zero, but towards the null of the test which equates squared bias with estimation variance. We derive the asymptotic distribution and show that the predictor can substantially lower...

  2. Charged weak currents

    CERN Document Server

    Turlay, René

    1979-01-01

    In this review of charged weak currents the author concentrates on inclusive high energy neutrino physics. The authors discusses the general structure of charged currents, new results on total cross- sections, the Callan-Gross relation, antiquark distributions, scaling violations and tests of QCD. A very short summary on multilepton physics is given. (44 refs).

  3. On Weak Markov's Principle

    DEFF Research Database (Denmark)

    Kohlenbach, Ulrich Wilhelm

    2002-01-01

    We show that the so-called weak Markov's principle (WMP) which states that every pseudo-positive real number is positive is underivable in E-HA + AC. Since allows one to formalize (atl eastl arge parts of) Bishop's constructive mathematics, this makes it unlikely that WMP can be proved within...

  4. Pulse-to-pulse intensity modulation and drifting subpulses in recycled pulsars

    OpenAIRE

    Edwards, R; Stappers, B. W.

    2003-01-01

    We report the detection of pulse-to-pulse periodic intensity modulations, in observations of recycled pulsars. Even though the detection of individual pulses was generally not possible due to their low flux density and short duration, through the accumulation of statistics over sequences of 10^5--10^6 pulses we were able to determine the presence and properties of the pulse-to-pulse intensity variations of six pulsars. In most cases we found that the modulation included a weak, broadly quasi-...

  5. Pulse growth dynamics in laser mode locking

    Science.gov (United States)

    Popov, Mark; Gat, Omri

    2018-01-01

    We analyze theoretically and numerically the nonlinear process of pulse formation in mode-locked lasers, starting from a perturbation of a continuous wave. Focusing on weak-to-moderate dispersion systems, we show that pulse growth is initially slow, dominated by a cascade of energy from low to high axial modes, followed by fast strongly nonlinear growth, and finally relaxation to the stable pulse wave form. The pulse grows initially by condensing a fixed amount of energy into a decreasing time interval, with peak power growing toward a finite-time singularity that is checked when the gain bandwidth is saturated by the pulse.

  6. Weak lensing with GEST

    Science.gov (United States)

    Rhodes, J. D.; Bennett, D. P.; Kaiser, N.

    2001-12-01

    Weak lensing by large-scale structure (cosmic shear) provides an opportunity to directly observe the dark matter in the universe. Current ground-based and space-based surveys have demonstrated the efficacy of this technique in determining the mass distribution and thus placing constraints on cosmological parameters such as Ω m, σ 8, and the bias parameter b. Current surveys have been hampered by the comparatively low resolution of ground-based telescopes and the small field of view of HST. To make significant progress in this field, wide field space-based surveys are needed. The Galactic Exoplanet Survey Telescope (GEST) will be able to provide 500- 1000 sqare degrees with a resolution of better than 0.2 arcseconds in multiple filters. This will make it an ideal instrument for a weak lensing survey.

  7. Composite weak bosons

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, M.

    1988-04-01

    Dynamical mechanism of composite W and Z is studied in a 1/N field theory model with four-fermion interactions in which global weak SU(2) symmetry is broken explicitly by electromagnetic interaction. Issues involved in such a model are discussed in detail. Deviation from gauge coupling due to compositeness and higher order loop corrections are examined to show that this class of models are consistent not only theoretically but also experimentally.

  8. The Weak Haagerup Property II

    DEFF Research Database (Denmark)

    Haagerup, Uffe; Knudby, Søren

    2015-01-01

    The weak Haagerup property for locally compact groups and the weak Haagerup constant were recently introduced by the second author [27]. The weak Haagerup property is weaker than both weak amenability introduced by Cowling and the first author [9] and the Haagerup property introduced by Connes [6......] and Choda [5]. In this paper, it is shown that a connected simple Lie group G has the weak Haagerup property if and only if the real rank of G is zero or one. Hence for connected simple Lie groups the weak Haagerup property coincides with weak amenability. Moreover, it turns out that for connected simple...... Lie groups the weak Haagerup constant coincides with the weak amenability constant, although this is not true for locally compact groups in general. It is also shown that the semidirect product R2 × SL(2,R) does not have the weak Haagerup property....

  9. Measurement of weak radioactivity

    CERN Document Server

    Theodorsson , P

    1996-01-01

    This book is intended for scientists engaged in the measurement of weak alpha, beta, and gamma active samples; in health physics, environmental control, nuclear geophysics, tracer work, radiocarbon dating etc. It describes the underlying principles of radiation measurement and the detectors used. It also covers the sources of background, analyzes their effect on the detector and discusses economic ways to reduce the background. The most important types of low-level counting systems and the measurement of some of the more important radioisotopes are described here. In cases where more than one type can be used, the selection of the most suitable system is shown.

  10. ICU-Acquired Weakness.

    Science.gov (United States)

    Jolley, Sarah E; Bunnell, Aaron E; Hough, Catherine L

    2016-11-01

    Survivorship after critical illness is an increasingly important health-care concern as ICU use continues to increase while ICU mortality is decreasing. Survivors of critical illness experience marked disability and impairments in physical and cognitive function that persist for years after their initial ICU stay. Newfound impairment is associated with increased health-care costs and use, reductions in health-related quality of life, and prolonged unemployment. Weakness, critical illness neuropathy and/or myopathy, and muscle atrophy are common in patients who are critically ill, with up to 80% of patients admitted to the ICU developing some form of neuromuscular dysfunction. ICU-acquired weakness (ICUAW) is associated with longer durations of mechanical ventilation and hospitalization, along with greater functional impairment for survivors. Although there is increasing recognition of ICUAW as a clinical entity, significant knowledge gaps exist concerning identifying patients at high risk for its development and understanding its role in long-term outcomes after critical illness. This review addresses the epidemiologic and pathophysiologic aspects of ICUAW; highlights the diagnostic challenges associated with its diagnosis in patients who are critically ill; and proposes, to our knowledge, a novel strategy for identifying ICUAW. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  11. STUCTURE OF PULSED BED

    Directory of Open Access Journals (Sweden)

    I. A. Bokun

    2014-01-01

    Full Text Available The structure of pulsed layer is proposed which can be suggested as a state of particulates that is blown by intermittent gas flow with speed which has the force to start material moving. Layer during one cycle is in a suspension, falling down and immobile state resulting in changes of particles arrangement as well as ways of gas flowing through layer. Moreover, it allows carrying out effective interphase heat exchange even adamant real granulation.The process of formation of impact flows is considered aw well as their influence on formation of air bubbles in pulsed layer. At startup of air blast the balance between the force of hydro-dynamic resistance is broken, on one side, and forces of gravity, particles inertia and their links with walls on the other side. The layer is transferred in the state of pulsed pseudo-fluidization, and presents gas-disperse mixture, inside of which impulse of pressure increasing is spreading to all sides as pressure waves (compression. These waves are the sources of impact flows’ formation, the force of which is two times more than during the stationary flow.The waves of pressure are divided into weak and strong ones depending on movement velocity within gas-disperse system. Weak waves are moving with a sound speed and strong ones in active phase of pulsed layer are moving over the speed of sound limit within gas-disperse system. The peculiarity of strong wave is that parameters of system (pressure, density and others are changing in discrete steps.The article describes the regime of layer’s falling down in the passive stage of cycle, which begins after finishing of gas impulse action. And suspension layer of moving up granular material is transferred in the state of falling resulting in change of the layer structure.

  12. Pulse Oximetry

    Science.gov (United States)

    ... people need more oxygen when asleep than when awake. Some need more oxygen with activity than when ... oxygen saturation levels (below 80%) or with very dark skin. When should I use a pulse oximeter? ...

  13. Weak Quantum Ergodicity

    CERN Document Server

    Kaplan, L

    1998-01-01

    We examine the consequences of classical ergodicity for the localization properties of individual quantum eigenstates in the classical limit. We note that the well known Schnirelman result is a weaker form of quantum ergodicity than the one implied by random matrix theory. This suggests the possibility of systems with non-gaussian random eigenstates which are nonetheless ergodic in the sense of Schnirelman and lead to ergodic transport in the classical limit. These we call "weakly quantum ergodic.'' Indeed for a class of "slow ergodic" classical systems, it is found that each eigenstate becomes localized to an ever decreasing fraction of the available state space, in the semiclassical limit. Nevertheless, each eigenstate in this limit covers phase space evenly on any classical scale, and long-time transport properties betwen individual quantum states remain ergodic due to the diffractive effects which dominate quantum phase space exploration.

  14. Time-resolved measurements with intense ultrashort laser pulses: a 'molecular movie' in real time

    Energy Technology Data Exchange (ETDEWEB)

    Rudenko, A; Ergler, Th; Feuerstein, B; Zrost, K; Schroeter, C D; Moshammer, R; Ullrich, J [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1 69117 Heidelberg (Germany)

    2007-11-15

    We report on the high-resolution multidimensional real-time mapping of H{sub 2}{sup +} and D{sub 2}{sup +} nuclear wave packets performed employing time-resolved three-dimensional Coulomb explosion imaging with intense laser pulses. Exploiting a combination of a 'reaction microscope' spectrometer and a pump-probe setup with two intense 6-7 fs laser pulses, we simultaneously visualize both vibrational and rotational motion of the molecule, and obtain a sequence of snapshots of the squared ro-vibrational wave function with time-step resolution of {approx} 0.3 fs, allowing us to reconstruct a real-time movie of the ultrafast molecular motion. We observe fast dephasing, or 'collapse' of the vibrational wave packet and its subsequent revival, as well as signatures of rotational excitation. For D{sub 2}{sup +} we resolve also the fractional revivals resulting from the interference between the counter-propagating parts of the wave packet.

  15. Short-pulse, high-energy radiation generation from laser-wakefield accelerated electron beams

    Science.gov (United States)

    Schumaker, Will

    2013-10-01

    Recent experimental results of laser wakefield acceleration (LWFA) of ~GeV electrons driven by the 200TW HERCULES and the 400TW ASTRA-GEMINI laser systems and their subsequent generation of photons, positrons, and neutrons are presented. In LWFA, high-intensity (I >1019 W /cm2), ultra-short (τL counter-propagating, ultra-high intensity (I >1021 W /cm2) laser pulse to undergo inverse Compton scattering and emit a high-peak brightness beam of high-energy photons. Preliminary results and experimental sensitivities of the electron-laser beam overlap are presented. The high-energy photon beams can be spectrally resolved using a forward Compton scattering spectrometer. Moreover, the photon flux can be characterized by a pixelated scintillator array and by nuclear activation and (γ,n) neutron measurements from the photons interacting with a secondary solid target. Monte-Carlo simulations were performed using FLUKA to support the yield estimates. This research was supported by DOE/NSF-PHY 0810979, NSF CAREER 1054164, DARPA AXiS N66001-11-1-4208, SF/DNDO F021166, and the Leverhulme Trust ECF-2011-383.

  16. Photodiode Preamplifier for Laser Ranging With Weak Signals

    Science.gov (United States)

    Abramovici, Alexander; Chapsky, Jacob

    2007-01-01

    An improved preamplifier circuit has been designed for processing the output of an avalanche photodiode (APD) that is used in a high-resolution laser ranging system to detect laser pulses returning from a target. The improved circuit stands in contrast to prior such circuits in which the APD output current pulses are made to pass, variously, through wide-band or narrow-band load networks before preamplification. A major disadvantage of the prior wide-band load networks is that they are highly susceptible to noise, which degrades timing resolution. A major disadvantage of the prior narrow-band load networks is that they make it difficult to sample the amplitudes of the narrow laser pulses ordinarily used in ranging. In the improved circuit, a load resistor is connected to the APD output and its value is chosen so that the time constant defined by this resistance and the APD capacitance is large, relative to the duration of a laser pulse. The APD capacitance becomes initially charged by the pulse of current generated by a return laser pulse, so that the rise time of the load-network output is comparable to the duration of the return pulse. Thus, the load-network output is characterized by a fast-rising leading edge, which is necessary for accurate pulse timing. On the other hand, the resistance-capacitance combination constitutes a lowpass filter, which helps to suppress noise. The long time constant causes the load network output pulse to have a long shallow-sloping trailing edge, which makes it easy to sample the amplitude of the return pulse. The output of the load network is fed to a low-noise, wide-band amplifier. The amplifier must be a wide-band one in order to preserve the sharp pulse rise for timing. The suppression of noise and the use of a low-noise amplifier enable the ranging system to detect relatively weak return pulses.

  17. Pulse plating

    CERN Document Server

    Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

    2012-01-01

    The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

  18. Weak Measurement and Quantum Correlation

    Indian Academy of Sciences (India)

    Arun Kumar Pati

    The concept of the weak measurements, for the first time, was introduced by Aharonov et al.1. Quantum state is preselected in |ψi〉 and allowed to interact weakly with apparatus. Measurement strength can be tuned and for “small g(t)” it is called 'weak measurement'. With postselection in |ψf 〉, apparatus state is shifted by an ...

  19. Resisting Weakness of the Will.

    Science.gov (United States)

    Levy, Neil

    2011-01-01

    I develop an account of weakness of the will that is driven by experimental evidence from cognitive and social psychology. I will argue that this account demonstrates that there is no such thing as weakness of the will: no psychological kind corresponds to it. Instead, weakness of the will ought to be understood as depletion of System II resources. Neither the explanatory purposes of psychology nor our practical purposes as agents are well-served by retaining the concept. I therefore suggest that we ought to jettison it, in favour of the vocabulary and concepts of cognitive psychology.

  20. Weak Coupling Phases future directions

    CERN Document Server

    Rosner, Jonathan L.

    2003-01-01

    Recent results obtained from B decays on the phases of weak couplings described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix are discussed, with particular emphasis on $\\alpha$ and $\\gamma = \\pi - \\beta - \\alpha$.

  1. Weakly compact operators and interpolation

    OpenAIRE

    Maligranda, Lech

    1992-01-01

    The class of weakly compact operators is, as well as the class of compact operators, a fundamental operator ideal. They were investigated strongly in the last twenty years. In this survey, we have collected and ordered some of this (partly very new) knowledge. We have also included some comments, remarks and examples. The class of weakly compact operators is, as well as the class of compact operators, a fundamental operator ideal. They were investigated strongly in the last twenty years. I...

  2. Weak interactions of elementary particles

    CERN Document Server

    Okun, Lev Borisovich

    1965-01-01

    International Series of Monographs in Natural Philosophy, Volume 5: Weak Interaction of Elementary Particles focuses on the composition, properties, and reactions of elementary particles and high energies. The book first discusses elementary particles. Concerns include isotopic invariance in the Sakata model; conservation of fundamental particles; scheme of isomultiplets in the Sakata model; universal, unitary-symmetric strong interaction; and universal weak interaction. The text also focuses on spinors, amplitudes, and currents. Wave function, calculation of traces, five bilinear covariants,

  3. Acute muscular weakness in children

    Directory of Open Access Journals (Sweden)

    Ricardo Pablo Javier Erazo Torricelli

    Full Text Available ABSTRACT Acute muscle weakness in children is a pediatric emergency. During the diagnostic approach, it is crucial to obtain a detailed case history, including: onset of weakness, history of associated febrile states, ingestion of toxic substances/toxins, immunizations, and family history. Neurological examination must be meticulous as well. In this review, we describe the most common diseases related to acute muscle weakness, grouped into the site of origin (from the upper motor neuron to the motor unit. Early detection of hyperCKemia may lead to a myositis diagnosis, and hypokalemia points to the diagnosis of periodic paralysis. Ophthalmoparesis, ptosis and bulbar signs are suggestive of myasthenia gravis or botulism. Distal weakness and hyporeflexia are clinical features of Guillain-Barré syndrome, the most frequent cause of acute muscle weakness. If all studies are normal, a psychogenic cause should be considered. Finding the etiology of acute muscle weakness is essential to execute treatment in a timely manner, improving the prognosis of affected children.

  4. Precision metrology using weak measurements.

    Science.gov (United States)

    Zhang, Lijian; Datta, Animesh; Walmsley, Ian A

    2015-05-29

    Weak values and measurements have been proposed as a means to achieve dramatic enhancements in metrology based on the greatly increased range of possible measurement outcomes. Unfortunately, the very large values of measurement outcomes occur with highly suppressed probabilities. This raises three vital questions in weak-measurement-based metrology. Namely, (Q1) Does postselection enhance the measurement precision? (Q2) Does weak measurement offer better precision than strong measurement? (Q3) Is it possible to beat the standard quantum limit or to achieve the Heisenberg limit with weak measurement using only classical resources? We analyze these questions for two prototypical, and generic, measurement protocols and show that while the answers to the first two questions are negative for both protocols, the answer to the last is affirmative for measurements with phase-space interactions, and negative for configuration space interactions. Our results, particularly the ability of weak measurements to perform at par with strong measurements in some cases, are instructive for the design of weak-measurement-based protocols for quantum metrology.

  5. Quantum discord with weak measurements

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Uttam, E-mail: uttamsingh@hri.res.in; Pati, Arun Kumar, E-mail: akpati@hri.res.in

    2014-04-15

    Weak measurements cause small change to quantum states, thereby opening up the possibility of new ways of manipulating and controlling quantum systems. We ask, can weak measurements reveal more quantum correlation in a composite quantum state? We prove that the weak measurement induced quantum discord, called as the “super quantum discord”, is always larger than the quantum discord captured by the strong measurement. Moreover, we prove the monotonicity of the super quantum discord as a function of the measurement strength and in the limit of strong projective measurement the super quantum discord becomes the normal quantum discord. We find that unlike the normal discord, for pure entangled states, the super quantum discord can exceed the quantum entanglement. Our results provide new insights on the nature of quantum correlation and suggest that the notion of quantum correlation is not only observer dependent but also depends on how weakly one perturbs the composite system. We illustrate the key results for pure as well as mixed entangled states. -- Highlights: •Introduced the role of weak measurements in quantifying quantum correlation. •We have introduced the notion of the super quantum discord (SQD). •For pure entangled state, we show that the SQD exceeds the entanglement entropy. •This shows that quantum correlation depends not only on observer but also on measurement strength.

  6. Warping the Weak Gravity Conjecture

    Directory of Open Access Journals (Sweden)

    Karta Kooner

    2016-08-01

    Full Text Available The Weak Gravity Conjecture, if valid, rules out simple models of Natural Inflation by restricting their axion decay constant to be sub-Planckian. We revisit stringy attempts to realise Natural Inflation, with a single open string axionic inflaton from a probe D-brane in a warped throat. We show that warped geometries can allow the requisite super-Planckian axion decay constant to be achieved, within the supergravity approximation and consistently with the Weak Gravity Conjecture. Preliminary estimates of the brane backreaction suggest that the probe approximation may be under control. However, there is a tension between large axion decay constant and high string scale, where the requisite high string scale is difficult to achieve in all attempts to realise large field inflation using perturbative string theory. We comment on the Generalized Weak Gravity Conjecture in the light of our results.

  7. Cosmology and the weak interaction

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, D.N. (Fermi National Accelerator Lab., Batavia, IL (USA)):(Chicago Univ., IL (USA))

    1989-12-01

    The weak interaction plays a critical role in modern Big Bang cosmology. This review will emphasize two of its most publicized cosmological connections: Big Bang nucleosynthesis and Dark Matter. The first of these is connected to the cosmological prediction of Neutrino Flavours, N{sub {nu}} {approximately} 3 which is now being confirmed at SLC and LEP. The second is interrelated to the whole problem of galaxy and structure formation in the universe. This review will demonstrate the role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure. 87 refs., 3 figs., 5 tabs.

  8. Nonlinear waves and weak turbulence

    CERN Document Server

    Zakharov, V E

    1997-01-01

    This book is a collection of papers on dynamical and statistical theory of nonlinear wave propagation in dispersive conservative media. Emphasis is on waves on the surface of an ideal fluid and on Rossby waves in the atmosphere. Although the book deals mainly with weakly nonlinear waves, it is more than simply a description of standard perturbation techniques. The goal is to show that the theory of weakly interacting waves is naturally related to such areas of mathematics as Diophantine equations, differential geometry of waves, Poincaré normal forms, and the inverse scattering method.

  9. Counter-propagating wave interaction for contrast-enhanced ultrasound imaging

    NARCIS (Netherlands)

    G. Renaud (G.); J.G. Bosch (Hans); E.J.G. Sijbrands (Eric); V. Shamdasani (V.); R. Entrekin (R.); N. de Jong (Nico); A.F.W. van der Steen (Ton)

    2012-01-01

    textabstractMost techniques for contrast-enhanced ultrasound imaging require linear propagation to detect nonlinear scattering of contrast agent microbubbles. Waveform distortion due to nonlinear propagation impairs their ability to distinguish microbubbles from tissue. As a result, tissue can be

  10. Absolute instability from linear conversion of counter-propagating positive and negative energy waves

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, A.N.; Brizard, A.J.; Morehead, J.J. [Lawrence Berkeley National Lab., CA (United States); Tracy, E.R. [College of William and Mary, Williamsburg, VA (United States)

    1997-12-31

    The resonant interaction of a negative-energy wave with a positive-energy wave gives rise to a linear instability. Whereas a single crossing of rays in a nonuniform medium leads to a convectively saturated instability, we show that a double crossing can yield an absolute instability.

  11. Simulations of collisionless counter-propagating plasma flows in support of two-wire implosion experiments

    Science.gov (United States)

    Caplinger, James; Sotnikov, Vladimir; Hamilton, Andrew; Plasma Physics Sensors Laboratory Team

    2017-10-01

    One of the simplest configurations leading to colliding plasma flows is created by driving strong currents through a pair of parallel wires. The azimuthal magnetic fields generated around each wire, and the Ohmic current dissipation and heating occurring upon wire evaporation, launches powerful radial outflows of magnetized plasmas. Upon colliding they form a flow pattern suggestive of magnetic field reconnection, and the development of various plasma instabilities. In the current effort, we analyzed collision of two high-temperature precursor light ion plasma flows via PIC (Particle-In-Cell) simulations using LSP. The aim is to demonstrate the appearance of an electric field parallel to the direction of a plasma flow. This field appears in colliding plasma flows due to the charge separation and is associated with the Buneman instability. It is responsible for the creation of ExB drift of electrons. Next, an interaction between drifting electrons and unmagnetized ions, moving parallel to them, lead to excitation of a modified Buneman instability in the frequency range close to the Lower-Hybrid frequency. Simulation results will allow us to identify the characteristics of nonlinear density fluctuations that appear in the process of such an interaction. This work was supported by the Air Force Office of Scientific Research.

  12. Counter-Propagating Optical Trapping System for Size and Refractive Index Measurement of Microparticles

    National Research Council Canada - National Science Library

    Flynn, Richard A; Shao, Bing; Chachisvilis, Mirianas; Ozkan, Mihrimah; Esener, Sadik C

    2005-01-01

    We propose and demonstrate a novel approach to measure the size and refractive index of microparticles based on two beam optical trapping, where forward scattered light is detected to give information about the particle...

  13. Submanifolds weakly associated with graphs

    Indian Academy of Sciences (India)

    Sci. (Math. Sci.) Vol. 119, No. 3, June 2009, pp. 297–318. © Printed in India. Submanifolds weakly associated with graphs. A CARRIAZO, L M FERN ´ANDEZ and A RODRÍGUEZ-HIDALGO. Department of Geometry and Topology, Faculty of Mathematics, University of Sevilla,. Apartado de Correos 1160, 41080-Sevilla, Spain.

  14. Beam splitting on weak illumination.

    Science.gov (United States)

    Snyder, A W; Buryak, A V; Mitchell, D J

    1998-01-01

    We demonstrate, in both two and three dimensions, how a self-guided beam in a non-Kerr medium is split into two beams on weak illumination. We also provide an elegant physical explanation that predicts the universal character of the observed phenomenon. Possible applications of our findings to guiding light with light are also discussed.

  15. On Weak-BCC-Algebras

    Science.gov (United States)

    Thomys, Janus; Zhang, Xiaohong

    2013-01-01

    We describe weak-BCC-algebras (also called BZ-algebras) in which the condition (x∗y)∗z = (x∗z)∗y is satisfied only in the case when elements x, y belong to the same branch. We also characterize ideals, nilradicals, and nilpotent elements of such algebras. PMID:24311983

  16. Voltage Weak DC Distribution Grids

    NARCIS (Netherlands)

    Hailu, T.G.; Mackay, L.J.; Ramirez Elizondo, L.M.; Ferreira, J.A.

    2017-01-01

    This paper describes the behavior of voltage weak DC distribution systems. These systems have relatively small system capacitance. The size of system capacitance, which stores energy, has a considerable effect on the value of fault currents, control complexity, and system reliability. A number of

  17. Competing weak localization and weak antilocalization in ultrathin topological insulators.

    Science.gov (United States)

    Lang, Murong; He, Liang; Kou, Xufeng; Upadhyaya, Pramey; Fan, Yabin; Chu, Hao; Jiang, Ying; Bardarson, Jens H; Jiang, Wanjun; Choi, Eun Sang; Wang, Yong; Yeh, Nai-Chang; Moore, Joel; Wang, Kang L

    2013-01-09

    We demonstrate evidence of a surface gap opening in topological insulator (TI) thin films of (Bi(0.57)Sb(0.43))(2)Te(3) below six quintuple layers through transport and scanning tunneling spectroscopy measurements. By effective tuning the Fermi level via gate-voltage control, we unveil a striking competition between weak localization and weak antilocalization at low magnetic fields in nonmagnetic ultrathin films, possibly owing to the change of the net Berry phase. Furthermore, when the Fermi level is swept into the surface gap of ultrathin samples, the overall unitary behaviors are revealed at higher magnetic fields, which are in contrast to the pure WAL signals obtained in thicker films. Our findings show an exotic phenomenon characterizing the gapped TI surface states and point to the future realization of quantum spin Hall effect and dissipationless TI-based applications.

  18. Pulsed laser illumination of photovoltaic cells

    Science.gov (United States)

    Yater, Jane A.; Lowe, Roland A.; Jenkins, Phillip P.; Landis, Geoffrey A.

    1995-01-01

    In future space missions, free electron lasers (FEL) may be used to illuminate photovoltaic receivers to provide remote power. Both the radio-frequency (RF) and induction FEL produce pulsed rather than continuous output. In this work we investigate cell response to pulsed laser light which simulates the RF FEL format. The results indicate that if the pulse repetition is high, cell efficiencies are only slightly reduced compared to constant illumination at the same wavelength. The frequency response of the cells is weak, with both voltage and current outputs essentially dc in nature. Comparison with previous experiments indicates that the RF FEL pulse format yields more efficient photovoltaic conversion than does an induction FEL format.

  19. Coherent Control of Photofragment Distributions Using Laser Phase Modulation in the Weak-Field Limit

    DEFF Research Database (Denmark)

    Garcia-Vela, Alberto; Henriksen, Niels Engholm

    2015-01-01

    The possibility of quantum interference control of the final state distributions of photodissociation fragments by means of pure phase modulation of the pump laser pulse in the weak-field regime is demonstrated theoretically for the first time. The specific application involves realistic wave...... to persist for long times (about 200 ps) after the pulse is over due to interference between overlapping resonances in Ne-Br-2(B)....

  20. Optimal Weak Lensing Skewness Measurements

    OpenAIRE

    Zhang, Tong-Jie; Pen, Ue-Li; Zhang, Pengjie; Dubinski, John

    2003-01-01

    Weak lensing measurements are entering a precision era to statistically map the distribution of matter in the universe. The most common measurement has been of the variance of the projected surface density of matter, which corresponds to the induced correlation in alignments of background galaxies. This measurement of the fluctuations is insensitive to the total mass content, like using waves on the ocean to measure its depths. But when the depth is shallow as happens near a beach, waves beco...

  1. Weak neutral-current interactions

    Energy Technology Data Exchange (ETDEWEB)

    Barnett, R.M.

    1978-08-01

    The roles of each type of experiment in establishing uniquely the values of the the neutral-current couplings of u and d quarks are analyzed together with their implications for gauge models of the weak and electromagnetic interactions. An analysis of the neutral-current couplings of electrons and of the data based on the assumption that only one Z/sup 0/ boson exists is given. Also a model-independent analysis of parity violation experiments is discussed. 85 references. (JFP)

  2. [Muscle weakness in cerebral palsy].

    Science.gov (United States)

    Givon, Uri

    2009-01-01

    Over the last two decades, muscle weakness has been shown to be a major component of cerebral palsy (CP) pathology. Caused by multiple etiologies including variations in the muscle fiber type, pathologic motor unit function, co-contraction of agonists and antagonists, and muscle size and rigidity, weakness interferes with function and leads to limited function and participation. Muscle strength was found to be associated with walking ability and with functional scales. Children with CP were found to be weaker than typically developing children, and differences were found with respect to muscle groups in children with CP. Muscle weakness should be evaluated as objectively as possible to improve the quality of diagnosis and treatment. Manual muscle testing is not sufficient for evaluation, and instrumented muscle testing is validated in CP. Muscle strengthening is an important part of treatment of CP. Several methods of strengthening have been described. Muscle lengthening and other spasticity-modifying therapies have been shown to have a positive effect on muscle strength. Children who participated in muscle strengthening programs had a better quality of life and improved function.

  3. Pulse-train control of photofragmentation at constant field energy

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Henriksen, Niels Engholm

    2014-01-01

    We consider a phaselocked two-pulse sequence applied to photofragmentation in the weak-field limit. The two pulses are not overlapping in time, i.e., the energy of the pulse-train is constant for all time delays. It is shown that the relative yield of excited Br* in the nonadiabatic process: I + Br......*←IBr → I + Br, changes as a function of time delay when the two excited wave packets interfere. The underlying mechanisms are analyzed and the change in the branching ratio as a function of time delay is only a reflection of a changing frequency distribution of the pulse train; the branching ratio does...

  4. Completely continuous and weakly completely continuous abstract ...

    Indian Academy of Sciences (India)

    if the operator ρa of right multiplication by a is compact (weakly compact, respectively). An algebra A is called right completely continuous (right weakly completely continuous) if any element a ∈ A is right completely continuous (right weakly completely con- tinuous, respectively). Left completely continuous (left weakly ...

  5. Inductive Pulse Generation

    OpenAIRE

    Lindblom, Adam

    2006-01-01

    Pulsed power generators are a key component in compact systems for generation of high-power microwaves (HPM). HPM generation by virtual cathode devices such as Vircators put high demands on the source. The rise time and the pulse length of the source voltage are two key issues in the generation of HPM radiation. This thesis describes the construction and tests of several inductive high power pulse generators. The pulse generators were designed with the intent to deliver a pulse with fast rise...

  6. Protecting weak measurements against systematic errors

    OpenAIRE

    Pang, Shengshi; Alonso, Jose Raul Gonzalez; Brun, Todd A.; Jordan, Andrew N.

    2016-01-01

    In this work, we consider the systematic error of quantum metrology by weak measurements under decoherence. We derive the systematic error of maximum likelihood estimation in general to the first-order approximation of a small deviation in the probability distribution, and study the robustness of standard weak measurement and postselected weak measurements against systematic errors. We show that, with a large weak value, the systematic error of a postselected weak measurement when the probe u...

  7. Gossip and Distributed Kalman Filtering: Weak Consensus Under Weak Detectability

    Science.gov (United States)

    Kar, Soummya; Moura, José M. F.

    2011-04-01

    The paper presents the gossip interactive Kalman filter (GIKF) for distributed Kalman filtering for networked systems and sensor networks, where inter-sensor communication and observations occur at the same time-scale. The communication among sensors is random; each sensor occasionally exchanges its filtering state information with a neighbor depending on the availability of the appropriate network link. We show that under a weak distributed detectability condition: 1. the GIKF error process remains stochastically bounded, irrespective of the instability properties of the random process dynamics; and 2. the network achieves \\emph{weak consensus}, i.e., the conditional estimation error covariance at a (uniformly) randomly selected sensor converges in distribution to a unique invariant measure on the space of positive semi-definite matrices (independent of the initial state.) To prove these results, we interpret the filtered states (estimates and error covariances) at each node in the GIKF as stochastic particles with local interactions. We analyze the asymptotic properties of the error process by studying as a random dynamical system the associated switched (random) Riccati equation, the switching being dictated by a non-stationary Markov chain on the network graph.

  8. Pulsed water jet generated by pulse multiplication

    Czech Academy of Sciences Publication Activity Database

    Dvorský, R.; Sitek, Libor; Sochor, T.

    2016-01-01

    Roč. 23, č. 4 (2016), s. 959-967 ISSN 1330-3651 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : high-pressure pulses * pulse intensifier * pulsed water jet * water hammer effect Subject RIV: JQ - Machines ; Tools Impact factor: 0.723, year: 2016 http://hrcak.srce.hr/163752?lang=en

  9. Weak polyelectrolytes in Confined Geometries

    Science.gov (United States)

    Whitmer, Jonathan K.; Rathee, Vikramjit S.; Sikora, Benjamin

    Crucial to the behavior of recently designed charge-rejection and mosaic membranes are the conformations of polyelectrolyte brushes and oligomeric grafts used to control the membranes' surface charge. The use of pH-tunable weak polyelectrolytes with associative interactions enables fine tuning of material transport properties. Here, we apply constant-pH molecular dynamics along with free energy sampling algorithms to understand the subtle tug-of-war between pH, salt concentrations, and solvation forces in confined systems, and determine how each of these effects alters transport within the system. We further discuss the implications of our findings for the design of electrolyte separation membranes.

  10. Weak lensing and cosmological investigation

    CERN Document Server

    Acquaviva, V

    2005-01-01

    In the last few years the scientific community has been dealing with the challenging issue of identifying the dark energy component. We regard weak gravitational lensing as a brand new, and extremely important, tool for cosmological investigation in this field. In fact, the features imprinted on the cosmic microwave background radiation by the lensing from the intervening distribution of matter represent a pretty unbiased estimator, and can thus be used for putting constraints on different dark energy models. This is true in particular for the magnetic-type B-modes of CMB polarization, whose unlensed spectrum at large multipoles (l approximately=1000) is very small even in presence of an amount of gravitational waves as large as currently allowed by the experiments: therefore, on these scales the lensing phenomenon is the only responsible for the observed power, and this signal turns out to be a faithful tracer of the dark energy dynamics. We first recall the formal apparatus of the weak lensing in extended t...

  11. Time—periodic weak solutions

    Directory of Open Access Journals (Sweden)

    Eliana Henriques de Brito

    1990-01-01

    Full Text Available In continuing from previous papers, where we studied the existence and uniqueness of the global solution and its asymptotic behavior as time t goes to infinity, we now search for a time-periodic weak solution u(t for the equation whose weak formulation in a Hilbert space H isddt(u′,v+δ(u′,v+αb(u,v+βa(u,v+(G(u,v=(h,vwhere: ′=d/dt; (′ is the inner product in H; b(u,v, a(u,v are given forms on subspaces U⊂W, respectively, of H; δ>0, α≥0, β≥0 are constants and α+β>0; G is the Gateaux derivative of a convex functional J:V⊂H→[0,∞ for V=U, when α>0 and V=W when α=0, hence β>0; v is a test function in V; h is a given function of t with values in H.

  12. Political corruption and weak state

    Directory of Open Access Journals (Sweden)

    Stojiljković Zoran

    2013-01-01

    Full Text Available The author starts from the hypothesis that it is essential for the countries of the region to critically assess the synergy established between systemic, political corruption and a selectively weak, “devious” nature of the state. Moreover, the key dilemma is whether the expanded practice of political rent seeking supports the conclusion that the root of all corruption is in the very existence of the state - particularly in excessive, selective and deforming state interventions and benefits that create a fertile ground for corruption? The author argues that the destructive combination of weak government and rampant political corruption is based on scattered state intervention, while also rule the parties cartel in the executive branch subordinate to parliament, the judiciary and the police. Corrupt exchange takes place with the absence of strong institutional framework and the precise rules of the political and electoral games, control of public finances and effective political and anti-monopoly legislation and practice included. Exit from the current situation can be seen in the realization of effective anti­corruption strategy that integrates preventive and repressive measures and activities and lead to the establishment of principles of good governance. [Projekat Ministarstva nauke Republike Srbije, br. 179076: Politički identitet Srbije u regionalnom i globalnom kontekstu

  13. Measurement and Control of Attosecond Pulses

    Science.gov (United States)

    2016-04-25

    the re-collision electron wave packet and therefore on the attosecond pulse that it produces. This modification deflects the beam and the deflection ...TYPE. State the type of report, such as final, technical, interim, memorandum, master’s thesis , progress, quarterly, research, special, group study...illustrated in Figure 1. A weak beam is incident on the nonlinear medium at a slight angle to the fundamental. It imposes a phased modification on

  14. Compact bright pulse and ultrashort-pulse in the nonlinear Kerr-like media

    Science.gov (United States)

    Pokam Nguewawe, Chancelor; Yemele, David; Donkeng, Hatou-Yvelin; Kofane, Timoléon Crépin

    2017-02-01

    The extended nonlinear Schrödinger equation describing the propagation of light beam in the weak nonlocal nonlinear media in general, and in the optical fibers with nearly instantaneous nonlinear response of the medium in particular, is investigated. In the zero-dispersion limit, we show that the system exhibits stable stationary compact bright pulse with an arbitrary nonlinear phase-shift both for the focusing and the defocusing media. However, in the presence of the large linear dispersion, this compact pulse become unstable and may be either disintegrate or transform into the ultrashort bright pulse according to whether the system operates in the normal or in the anomalous region. The exact analytical expressions of these two pulses are derived and the results checked through numerical simulations.

  15. Weak transitions in lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Maturana, G.

    1984-01-01

    Some techniques to calculate the effects of the strong interactions on the matrix elements of weak processes are described. The lattice formulation of Quantum Chromodynamics is used to account for the low energy gluons, and the corresponding numerical methods are explained. The high energy contributions are included in effective lagrangians and the problem of matching the different scales related to the renormalization of the operators and wavefunctions is also discussed. The ..delta..l = 1/2 enhancement rule and the K/sup 0/-anti-K/sup 0/ are used to illustrate these techniques and the results of a numerical calculation is reported. The values obtained are very encouraging and they certainly show good qualitative agreement with the experimental values. The emphasis is on general techniques, and in particular, several improvements to this particular calculation are proposed.

  16. Strengths, weaknesses, opportunities and threats

    DEFF Research Database (Denmark)

    Bull, Joseph William; Jobstvogt, N.; Böhnke-Henrichs, A.

    2016-01-01

    The ecosystem services concept (ES) is becoming a cornerstone of contemporary sustainability thought. Challenges with this concept and its applications are well documented, but have not yet been systematically assessed alongside strengths and external factors that influence uptake. Such an assess......The ecosystem services concept (ES) is becoming a cornerstone of contemporary sustainability thought. Challenges with this concept and its applications are well documented, but have not yet been systematically assessed alongside strengths and external factors that influence uptake....... Such an assessment could form the basis for improving ES thinking, further embedding it into environmental decisions and management.The Young Ecosystem Services Specialists (YESS) completed a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis of ES through YESS member surveys. Strengths include the approach...

  17. Fault zone fabric and fault weakness

    NARCIS (Netherlands)

    Collettini, C.; Niemeijer, A.; Viti, C.; Marone, C.

    2009-01-01

    Geological and geophysical evidence suggests that some crustal faults are weak1–6 compared to laboratory measurements of frictional strength7. Explanations for fault weakness include the presence of weak minerals4, high fluid pressures within the fault core8,9 and dynamic processes such as

  18. Weakly distributive modules. Applications to supplement submodules

    Indian Academy of Sciences (India)

    Abstract. In this paper, we define and study weakly distributive modules as a proper generalization of distributive modules. We prove that, weakly distributive supplemented modules are amply supplemented. In a weakly distributive supplemented module every submodule has a unique coclosure. This generalizes a result of ...

  19. Zeptosecond precision pulse shaping.

    Science.gov (United States)

    Köhler, Jens; Wollenhaupt, Matthias; Bayer, Tim; Sarpe, Cristian; Baumert, Thomas

    2011-06-06

    We investigate the temporal precision in the generation of ultrashort laser pulse pairs by pulse shaping techniques. To this end, we combine a femtosecond polarization pulse shaper with a polarizer and employ two linear spectral phase masks to mimic an ultrastable common-path interferometer. In an all-optical experiment we study the interference signal resulting from two temporally delayed pulses. Our results show a 2σ-precision of 300 zs = 300 × 10(-21) s in pulse-to-pulse delay. The standard deviation of the mean is 11 zs. The obtained precision corresponds to a variation of the arm's length in conventional delay stage based interferometers of 0.45 Å. We apply these precisely generated pulse pairs to a strong-field quantum control experiment. Coherent control of ultrafast electron dynamics via photon locking by temporal phase discontinuities on a few attosecond timescale is demonstrated.

  20. Weak matrix elements of kaons

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, C. (California Univ., Santa Barbara, CA (USA). Inst. for Theoretical Physics); Soni, A. (Brookhaven National Lab., Upton, NY (USA))

    1989-01-01

    We present results from the Wilson fermion part of the Grand Challenge'' weak matrix element project. A new procedure for correcting the chiral behavior of {Beta}{sub LL}{sup sd}, the K{sup 0}-{bar K}{sup 0} {Beta} parameter,'' is proposed and applied. On our largest lattice (24{sup 3} {times} 40 at {beta} = 6.0), we get {Beta}{sub LL}{sup sd} = .86 {plus minus} .11 {plus minus} .05, where the first error is statistical and the second is a measure of the systematic errors due to the procedure and to related finite-size effects. Results for the direct K{sup +} {yields} {pi}{sup +}{pi}{sup 0} amplitude are also presented. There is some evidence for higher order chiral effects which may make these results compatible both with experiment and with the {Beta}{sub LL}{sup sd} computation. The status of the direct K{sub s}{sup 0} {yields} {pi} {sup +} {pi}{sup {minus}} {Delta}I = 1/2 amplitude is then discussed. 11 refs., 6 figs., 1 tab.

  1. A Universe without Weak Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Harnik, Roni; Kribs, Graham D.; Perez, Gilad

    2006-04-07

    A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical ''Weakless Universe'' is matched to our Universe by simultaneously adjusting Standard Model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the Weakless Universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multi-parameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe.

  2. Protecting weak measurements against systematic errors

    Science.gov (United States)

    Pang, Shengshi; Alonso, Jose Raul Gonzalez; Brun, Todd A.; Jordan, Andrew N.

    2016-07-01

    In this work, we consider the systematic error of quantum metrology by weak measurements under decoherence. We derive the systematic error of maximum likelihood estimation in general to the first-order approximation of a small deviation in the probability distribution and study the robustness of standard weak measurement and postselected weak measurements against systematic errors. We show that, with a large weak value, the systematic error of a postselected weak measurement when the probe undergoes decoherence can be significantly lower than that of a standard weak measurement. This indicates another advantage of weak-value amplification in improving the performance of parameter estimation. We illustrate the results by an exact numerical simulation of decoherence arising from a bosonic mode and compare it to the first-order analytical result we obtain.

  3. Spin effects in the weak interaction

    Energy Technology Data Exchange (ETDEWEB)

    Freedman, S.J. (Argonne National Lab., IL (USA) Chicago Univ., IL (USA). Dept. of Physics Chicago Univ., IL (USA). Enrico Fermi Inst.)

    1990-01-01

    Modern experiments investigating the beta decay of the neutron and light nuclei are still providing important constraints on the theory of the weak interaction. Beta decay experiments are yielding more precise values for allowed and induced weak coupling constants and putting constraints on possible extensions to the standard electroweak model. Here we emphasize the implications of recent experiments to pin down the strengths of the weak vector and axial vector couplings of the nucleon.

  4. Weak isometries of the Boolean cube

    OpenAIRE

    Winter, S De; Korb, M

    2014-01-01

    Consider the metric space $\\mathcal{C}$ consisting of the $n$-dimensional Boolean cube equipped with the Hamming distance. A weak isometry of $\\mathcal{C}$ is a permutation of $\\mathcal{C}$ preserving a given subset of Hamming distances. In \\cite{Krasin} Krasin showed that in most cases preserving a single Hamming distance forces a weak isometry to be an isometry. In this article we study those weak isometries that are not automatically an isometry, providing a complete classification of weak...

  5. Pseudo-Weak-R0 Algebras

    Directory of Open Access Journals (Sweden)

    Yong Lin Liu

    2014-01-01

    Full Text Available A positive answer to the open problem of Iorgulescu on extending weak-R0 algebras and R0-algebras to the noncommutative forms is given. We show that pseudo-weak-R0 algebras are categorically isomorphic to pseudo-IMTL algebras and that pseudo-R0 algebras are categorically isomorphic to pseudo-NM algebras. Some properties, the noncommutative forms of the properties in weak-R0 algebras and R0-algebras, are investigated. The simplified axiom systems of pseudo-weak-R0 algebras and pseudo-R0 algebras are obtained.

  6. Pulse Tube Refrigerator

    Science.gov (United States)

    Matsubara, Yoichi

    The pulse tube refrigerator is one of the regenerative cycle refrigerators such as Stirling cycle or Gifford-McMahon cycle which gives the cooling temperature below 150 K down to liquid helium temperature. In 1963, W. E. Gifford invented a simple refrigeration cycle which is composed of compressor, regenerator and simple tube named as pulse tube which gives a similar function of the expander in Stirling or Gifford-McMahon cycle. The thermodynamically performance of this pulse tube refrigerator is inferior to that of other regenerative cycles. In 1984, however, Mikulin and coworkers made a significant advance in pulse tube configuration called as orifice pulse tube. After this, several modifications of the pulse tube hot end configuration have been developed. With those modifications, the thermodynamic performance of the pulse tube refrigerator became the same order to that of Stirling and Gifford-McMahon refrigerator. This article reviews the brief history of the pulse tube refrigerator development in the view point of its thermodynamically efficiency. Simplified theories of the energy flow in the pulse tube have also been described.

  7. Ultrashort Laser Pulse Phenomena

    CERN Document Server

    Diels, Jean-Claude

    2006-01-01

    Ultrashort Laser Pulse Phenomena, 2e serves as an introduction to the phenomena of ultra short laser pulses and describes how this technology can be used to examine problems in areas such as electromagnetism, optics, and quantum mechanics. Ultrashort Laser Pulse Phenomena combines theoretical backgrounds and experimental techniques and will serve as a manual on designing and constructing femtosecond (""faster than electronics"") systems or experiments from scratch. Beyond the simple optical system, the various sources of ultrashort pulses are presented, again with emphasis on the basic

  8. Apparatus and method for characterizing ultrafast polarization varying optical pulses

    Science.gov (United States)

    Smirl, A.; Trebino, R.P.

    1999-08-10

    Practical techniques are described for characterizing ultrafast potentially ultraweak, ultrashort optical pulses. The techniques are particularly suited to the measurement of signals from nonlinear optical materials characterization experiments, whose signals are generally too weak for full characterization using conventional techniques. 2 figs.

  9. Numerical continuation of travelling waves and pulses in neural fields

    NARCIS (Netherlands)

    Meijer, Hil Gaétan Ellart; Coombes, Stephen

    2013-01-01

    We study travelling waves and pulses in neural fields. Neural fields are a macroscopic description of the activity of brain tissue, which mathematically are formulated as integro-differential equations. While linear and weakly nonlinear analysis can describe instabilities and small amplitude

  10. A classification of weakly acyclic games

    NARCIS (Netherlands)

    Apt, K.R.; Simon, S.

    2012-01-01

    Weakly acyclic games form a natural generalization of the class of games that have the finite improvement property (FIP). In such games one stipulates that from any initial joint strategy some finite improvement path exists. We classify weakly acyclic games using the concept of a scheduler recently

  11. Revisiting Weak Simulation for Substochastic Markov Chains

    DEFF Research Database (Denmark)

    Jansen, David N.; Song, Lei; Zhang, Lijun

    2013-01-01

    The spectrum of branching-time relations for probabilistic systems has been investigated thoroughly by Baier, Hermanns, Katoen and Wolf (2003, 2005), including weak simulation for systems involving substochastic distributions. Weak simulation was proven to be sound w.r.t. the liveness fragment...

  12. A note on Weak Stability Boundaries

    OpenAIRE

    García González, Fernando; Gómez Muntané, Gerard

    2006-01-01

    This paper is devoted to clarify the algorithmic definition of the weak stability boundary in the framework of the planar Restricted Three Body Problem. The role of the invariant hyperbolic manifolds associated to the central manifolds of the libration points L1 and L2, as boundary of the weak stability region, is shown Peer Reviewed

  13. CP Violation, Neutral Currents, and Weak Equivalence

    Science.gov (United States)

    Fitch, V. L.

    1972-03-23

    Within the past few months two excellent summaries of the state of our knowledge of the weak interactions have been presented. Correspondingly, we will not attempt a comprehensive review but instead concentrate this discussion on the status of CP violation, the question of the neutral currents, and the weak equivalence principle.

  14. Towards a classification of weak hand holds

    NARCIS (Netherlands)

    Kimmelman, V.; Sáfár, A.; Crasborn, O.

    2016-01-01

    The two symmetrical manual articulators (the hands) in signed languages are a striking modalityspecific phonetic property. The weak hand can maintain the end position of an articulation while the other articulator continues to produce additional signs. This weak hand spreading (hold) has been

  15. Spin Seebeck effect in a weak ferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Arboleda, Juan David, E-mail: juan.arboledaj@udea.edu.co; Arnache Olmos, Oscar [Instituto de Física, Universidad de Antioquia, A.A. 1226, Medellín (Colombia); Aguirre, Myriam Haydee; Ibarra, Manuel Ricardo [Instituto de Nanociencia de Aragón, Universidad de Zaragoza, E-50018 Zaragoza (Spain); Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Laboratorio de Microscopías Avanzadas, Universidad de Zaragoza, E-50018 Zaragoza (Spain); Ramos, Rafael [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Spin Quantum Rectification Project, ERATO, Japan Science and Technology Agency, Sendai 980-8577 (Japan); Anadon, Alberto [Instituto de Nanociencia de Aragón, Universidad de Zaragoza, E-50018 Zaragoza (Spain); Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza (Spain)

    2016-06-06

    We report the observation of room temperature spin Seebeck effect (SSE) in a weak ferromagnetic normal spinel Zinc Ferrite (ZFO). Despite the weak ferromagnetic behavior, the measurements of the SSE in ZFO show a thermoelectric voltage response comparable with the reported values for other ferromagnetic materials. Our results suggest that SSE might possibly originate from the surface magnetization of the ZFO.

  16. On modeling weak sinks in MODPATH

    Science.gov (United States)

    Abrams, Daniel B.; Haitjema, Henk; Kauffman, Leon J.

    2012-01-01

    Regional groundwater flow systems often contain both strong sinks and weak sinks. A strong sink extracts water from the entire aquifer depth, while a weak sink lets some water pass underneath or over the actual sink. The numerical groundwater flow model MODFLOW may allow a sink cell to act as a strong or weak sink, hence extracting all water that enters the cell or allowing some of that water to pass. A physical strong sink can be modeled by either a strong sink cell or a weak sink cell, with the latter generally occurring in low resolution models. Likewise, a physical weak sink may also be represented by either type of sink cell. The representation of weak sinks in the particle tracing code MODPATH is more equivocal than in MODFLOW. With the appropriate parameterization of MODPATH, particle traces and their associated travel times to weak sink streams can be modeled with adequate accuracy, even in single layer models. Weak sink well cells, on the other hand, require special measures as proposed in the literature to generate correct particle traces and individual travel times and hence capture zones. We found that the transit time distributions for well water generally do not require special measures provided aquifer properties are locally homogeneous and the well draws water from the entire aquifer depth, an important observation for determining the response of a well to non-point contaminant inputs.

  17. Intensive care unit-acquired weakness

    NARCIS (Netherlands)

    Horn, J.; Hermans, G.

    2017-01-01

    When critically ill, a severe weakness of the limbs and respiratory muscles often develops with a prolonged stay in the intensive care unit (ICU), a condition vaguely termed intensive care unit-acquired weakness (ICUAW). Many of these patients have serious nerve and muscle injury. This syndrome is

  18. Pulse Distortion in Saturated Fiber Optical Parametric Chirped Pulse Amplification

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Da Ros, Francesco; Rottwitt, Karsten

    2012-01-01

    Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation....

  19. Persisting weakness after withdrawal of a statin.

    Science.gov (United States)

    Mygland, Åse; Ljøstad, Unn; Krossnes, Bård Kronen

    2014-04-08

    An 81-year-old woman treated with simvastatin for several years followed by atorvastatin for about 1 year presented with fatigue, weakness and unsteady gait. The finding of elevated creatine kinase (CK) and symmetric muscle weakness around shoulders and hips led to suspicion of a toxic statin-associated myopathy. Atorvastatin was withdrawn, but her weakness persisted. Owing to persisting weakness, an autoimmune myopathy (myositis) was suspected, but initially disregarded since a muscle biopsy showed necrotic muscle fibres without inflammatory cell infiltrates and myositis-specific autoantibodies were absent. After 18 months with slowly progressive weakness and increasing CK values, awareness of new knowledge about autoimmunity as a cause of necrotic myopathy, led to a successful treatment trial with intravenous immunoglobulines, followed by steroids and metothrexate. Antibodies to the target enzyme of statins (HMGCR (3-hydroksy-3-methylglutaryl-coenzyme A reductase)) were detected in her serum, and she was diagnosed with autoimmune necrotic myositis probably triggered by atorvastatin.

  20. Chaotic Pulse Trains

    CERN Document Server

    Balmforth, N J; Spiegel, E A

    1993-01-01

    Abstract: We study a third-order nonlinear ordinary differential equation whose solutions, under certain specific conditions, are individual pulses. These correspond to homoclinic orbits in the phase space of the equation and we study the possible pulse types in some detail. Sufficiently close to the conditions under which a homoclinic orbit exists, the solutions take the form of trains of well-separated pulses. A measure of closeness to homoclinic conditions provides a small parameter for the development of an asymptotic solution consisting of superposed, isolated pulses. The solvability condition in the resulting singular perturbation theory is a {\\its timing map} relating successive pulse spacings. This map of the real line onto itself, together with the known form of the homoclinic orbit, provides a concise and accurate solution of the equation.

  1. Weak Solution and Weakly Uniformly Bounded Solution of Impulsive Heat Equations Containing “Maximum” Temperature

    OpenAIRE

    Oyelami, Benjamin Oyediran

    2013-01-01

    In this paper, criteria for the existence of weak solutions and uniformly weak bounded solution of impulsive heat equation containing maximum temperature are investigated and results obtained. An example is given for heat flow system with impulsive temperature using maximum temperature simulator and criteria for the uniformly weak bounded of solutions of the system are obtained.

  2. Weak Solution and Weakly Uniformly Bounded Solution of Impulsive Heat Equations Containing “Maximum” Temperature

    Directory of Open Access Journals (Sweden)

    Oyelami, Benjamin Oyediran

    2013-09-01

    Full Text Available In this paper, criteria for the existence of weak solutions and uniformly weak bounded solution of impulsive heat equation containing maximum temperature are investigated and results obtained. An example is given for heat flow system with impulsive temperature using maximum temperature simulator and criteria for the uniformly weak bounded of solutions of the system are obtained.

  3. Quadriceps weakness and osteoarthritis of the knee.

    Science.gov (United States)

    Slemenda, C; Brandt, K D; Heilman, D K; Mazzuca, S; Braunstein, E M; Katz, B P; Wolinsky, F D

    1997-07-15

    The quadriceps weakness commonly associated with osteoarthritis of the knee is widely believed to result from disuse atrophy secondary to pain in the involved joint. However, quadriceps weakness may be an etiologic factor in the development of osteoarthritis. To explore the relation between lower-extremity weakness and osteoarthritis of the knee. Cross-sectional prevalence study. Population-based, with recruitment by random-digit dialing. 462 volunteers 65 years of age or older. Radiographs of the knee were graded for the presence of osteoarthritis. Knee pain and function were assessed with the Western Ontario and McMaster Universities Arthritis Index, the strength of leg flexors and extensors was assessed with isokinetic dynamometry, and lower-extremity lean tissue mass was assessed with dual-energy x-ray absorptiometry. Among participants with osteoarthritis, quadriceps weakness, but not hamstring weakness, was common. The ratio of extensor strength to body weight was approximately 20% lower in those with than in those without radiographic osteoarthritis. Notably, among women with tibiofemoral osteoarthritis, extensor weakness was present in the absence of knee pain and was seen in participants with normal lower-extremity lean mass (extensor strength, 30.1 lb-ft for those with osteoarthritis and 34.8 lb-ft for those without osteoarthritis; P osteoarthritis of the knee (odds ratio for prevalence of osteoarthritis per 10 lb-ft loss of strength, 0.8 [95% CI, 0.71 to 0.90] for radiographic osteoarthritis and 0.71 [CI, 0.51 to 0.87] for symptomatic osteoarthritis). Quadriceps weakness may be present in patients who have osteoarthritis but do not have knee pain or muscle atrophy; this suggests that the weakness may be due to muscle dysfunction. The data are consistent with the possibility that quadriceps weakness is a primary risk factor for knee pain, disability, and progression of joint damage in persons with osteoarthritis of the knee.

  4. RF Pulsed Heating

    Energy Technology Data Exchange (ETDEWEB)

    Pritzkau, David P.

    2002-01-03

    RF pulsed heating is a process by which a metal is heated from magnetic fields on its surface due to high-power pulsed RF. When the thermal stresses induced are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Pulsed heating limits the maximum magnetic field on the surface and through it the maximum achievable accelerating gradient in a normal conducting accelerator structure. An experiment using circularly cylindrical cavities operating in the TE{sub 011} mode at a resonant frequency of 11.424 GHz is designed to study pulsed heating on OFE copper, a material commonly used in normal conducting accelerator structures. The high-power pulsed RF is supplied by an X-band klystron capable of outputting 50 MW, 1.5 {micro}s pulses. The test pieces of the cavity are designed to be removable to allow testing of different materials with different surface preparations. A diagnostic tool is developed to measure the temperature rise in the cavity utilizing the dynamic Q change of the resonant mode due to heating. The diagnostic consists of simultaneously exciting a TE{sub 012} mode to steady-state in the cavity at 18 GHz and measuring the change in reflected power as the cavity is heated from high-power pulsed RF. Two experimental runs were completed. One run was executed at a calculated temperature rise of 120 K for 56 x 10{sup 6} pulses. The second run was executed at a calculated temperature rise of 82 K for 86 x 10{sup 6} pulses. Scanning electron microscope pictures show extensive damage occurring in the region of maximum temperature rise on the surface of the test pieces.

  5. Strong versus Weak Ties in Migration

    OpenAIRE

    Giulietti, Corrado; Wahba, Jackline; Zenou, Yves

    2014-01-01

    This paper studies the role of strong versus weak ties in the rural-to-urban migration decision in China. We first develop a network model that puts forward the different roles of weak and strong ties in helping workers to migrate to the city. We then use a unique longitudinal data that allows us to test our model by focusing on first-time migration. Strong ties are measured by the closest family contact (excluding household members) while weak ties are determined by the fraction of migrants ...

  6. Quantum correlation cost of the weak measurement

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jun; Wu, Shao-xiong; Yu, Chang-shui, E-mail: quaninformation@sina.com

    2014-12-15

    Quantum correlation cost (QCC) characterizing how much quantum correlation is used in a weak-measurement process is presented based on the trace norm. It is shown that the QCC is related to the trace-norm-based quantum discord (TQD) by only a factor that is determined by the strength of the weak measurement, so it only catches partial quantumness of a quantum system compared with the TQD. We also find that the residual quantumness can be ‘extracted’ not only by the further von Neumann measurement, but also by a sequence of infinitesimal weak measurements. As an example, we demonstrate our outcomes by the Bell-diagonal state.

  7. High performance pulse generator

    Science.gov (United States)

    Grothaus, Michael G.; Moran, Stuart L.; Hardesty, Leonard W.

    1992-06-01

    The device is a compact Marx-type generator capable of producing a high-voltage burst of pulses having risetimes less than 10 nanoseconds at repetition rates up to 10 kHz. High-pressure hydrogen switches are used as the switching elements to achieve high rep-rate. A small coaxial design provides low inductance and a fast risetime. The device may be used as a high-rep-rate high-voltage trigger generator, or as a high-voltage pulse source capable of producing up to 1 MV pulses at high repetition rates.

  8. Pulse joining cartridges

    Energy Technology Data Exchange (ETDEWEB)

    Golovashchenko, Sergey Fedorovich; Bonnen, John Joseph Francis

    2017-09-26

    A pulsed joining tool includes a tool body that defines a cavity that receives an inner tubular member and an outer tubular member and a pulse joining cartridge. The tubular members are nested together with the cartridge being disposed around the outer tubular member. The cartridge includes a conductor, such as a wire or foil, that extends around the outer tubular member and is insulated to separate a supply segment from a return segment. A source of stored electrical energy is discharged through the conductor to join the tubular members with an electromagnetic force pulse.

  9. SHORT PULSE STRETCHER

    Science.gov (United States)

    Branum, D.R.; Cummins, W.F.

    1962-12-01

    >A short pulse stretching circuit capable of stretching a short puise to enable it to be displayed on a relatively slow sweeping oscilloscope is described. Moreover, the duration of the pulse is increased by charging a capacitor through a diode and thereafter discharging the capacitor at such time as is desired. In the circuit the trigger pulse alone passes through a delay line, whereas the main signal passes through the diode only, and results in over-all circuit losses which are proportional to the low losses of the diode only. (AEC)

  10. DogPulse

    DEFF Research Database (Denmark)

    Skovgaard, Christoffer; Thomsen, Josephine Raun; Verdezoto, Nervo

    2015-01-01

    This paper presents DogPulse, an ambient awareness system to support the coordination of dog walking among family members at home. DogPulse augments a dog collar and leash set to activate an ambient shape-changing lamp and visualize the last time the dog was taken for a walk. The lamp gradually...... changes its form and pulsates its lights in order to keep the family members aware of the dog walking activity. We report the iterative prototyping of DogPulse, its implementation and its preliminary evaluation. Based on our initial findings, we present the limitations and lessons learned as well...

  11. Numerical investigation of enhanced femtosecond supercontinuum via a weak seed in noble gases.

    Science.gov (United States)

    Shanor, C; Ensley, T; Hagan, D J; Van Stryland, E W; Wright, E M; Kolesik, M

    2016-06-27

    Numerical simulations are employed to elucidate the physics underlying the enhanced femtosecond supercontinuum generation previously observed during optical filamentation in noble gases and in the presence of a weak seed pulse. Simulations based on the metastable electronic state approach are shown not only to capture the qualitative features of the experiment, but also reveal the relation of the observed enhancement to recent developments in the area of sub-cycle engineering of filaments.

  12. Current problems in the weak interactions

    Energy Technology Data Exchange (ETDEWEB)

    Pais, A

    1977-01-01

    Some reasons are discussed showing why the recent SU(2) x U(1) gauge theory of weak and electromagnetic interactions is not a complete theory of these interactions, Lepton theory, charm, and the CP problem are considered. 60 references. (JFP)

  13. Regularity of Tor for weakly stable ideals

    Directory of Open Access Journals (Sweden)

    Katie Ansaldi

    2015-05-01

    Full Text Available It is proved that if I and J are weakly stable ideals in a polynomial ring R = k[x_1, . . ., x_n], with k a field, then the regularity of Tor^R_i (R/I, R/J has the expected upper bound. We also give a bound for the regularity of Ext^i_R (R/I, R for I a weakly stable ideal.

  14. The regularization of Old English weak verbs

    OpenAIRE

    Marta Tío Sáenz

    2015-01-01

    [EN] This article deals with the regularization of non-standard spellings of the verbal forms extracted from a corpus. It addresses the question of what the limits of regularization are when lemmatizing Old English weak verbs. The purpose of such regularization, also known as normalization, is to carry out lexicological analysis or lexicographical work. The analysis concentrates on weak verbs from the second class and draws on the lexical database of Old English Nerthus, which has incorporate...

  15. Drift waves in a weakly ionized plasma

    DEFF Research Database (Denmark)

    Popovic, M.; Melchior, H.

    1968-01-01

    A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated.......A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated....

  16. Muscle weakness causes joint degeneration in rabbits.

    Science.gov (United States)

    Rehan Youssef, A; Longino, D; Seerattan, R; Leonard, T; Herzog, W

    2009-09-01

    The objective of this study was to investigate the effects of botulinum toxin type-A (BTX-A) induced quadriceps weakness on micro-structural changes in knee cartilage of New Zealand White (NZW) rabbits. Fifteen rabbits were divided randomly into an experimental and a sham control group. Each group received a unilateral single quadriceps muscle injection either with saline (sham control; n=4) or BTX-A (experimental; n=11). BTX-A injection produced significant quadriceps muscle weakness (Pmuscle mass (Pknee cartilage, assessed with the Mankin grading system, were the same for the injected and non-injected hind limbs of the experimental group animals. Sham injection had no effect on joint degeneration but all control animals showed some degenerative changes in the knee. Degenerative changes of the retro-patellar cartilage were more severe in the experimental compared to sham control group rabbits (P0.05). Quadriceps muscle weakness caused increased degeneration in the retro-patellar cartilage of NZW rabbits, providing evidence that muscle weakness might be a risk factor for the onset and progression of osteoarthritis (OA). Future work needs to delineate whether muscle weakness directly affects joint degeneration, or if changes in function and movement execution associated with muscle weakness are responsible for the increased rate of OA onset and progression observed here.

  17. Pulsed spallation Neutron Sources

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, J.M. [Argonne National Lab., IL (United States)

    1994-12-31

    This paper reviews the early history of pulsed spallation neutron source development at Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provides a few examples of applications in fundamental condensed matter physics, materials science and technology.

  18. A Computer Controlled Pulse Programmer for Pulsed NQR Experiments

    OpenAIRE

    Horiuchi, Keizo; 堀内, 敬三

    1987-01-01

    We constructed a computer controlled pulse programmer for the measurement of nuclear quadrupole resonance relaxation times. Programmable interval timer 8253 was used as device for pulse programming. The circuit is very simple and construction is also easy in comparison with the usual pulse programmer. This programmer is sufficiently useful concerning the pulse programming of slimple pulse sequences such as π-τ-π/2 and π/2-τ-π, which are usually used in the measurement of relaxation times. We ...

  19. SIMULATION OF SUBGRADE EMBANKMENT ON WEAK BASE

    Directory of Open Access Journals (Sweden)

    V. D. Petrenko

    2015-08-01

    Full Text Available Purpose. This article provides: the question of the sustainability of the subgrade on a weak base is considered in the paper. It is proposed to use the method of jet grouting. Investigation of the possibility of a weak base has an effect on the overall deformation of the subgrade; the identification and optimization of the parameters of subgrade based on studies using numerical simulation. Methodology. The theoretical studies of the stress-strain state of the base and subgrade embankment by modeling in the software package LIRA have been conducted to achieve this goal. Findings. After making the necessary calculations perform building fields of a subsidence, borders cramped thickness, bed’s coefficients of Pasternak and Winkler. The diagrams construction of vertical stress performs at any point of load application. Also, using the software system may perform peer review subsidence, rolls railroad tracks in natural and consolidated basis. Originality. For weak soils is the most appropriate nonlinear model of the base with the existing areas of both elastic and limit equilibrium, mixed problem of the theory of elasticity and plasticity. Practical value. By increasing the load on the weak base as a result of the second track construction, adds embankment or increasing axial load when changing the rolling stock process of sedimentation and consolidation may continue again. Therefore, one of the feasible and promising options for the design and reconstruction of embankments on weak bases is to strengthen the bases with the help of jet grouting. With the expansion of the railway infrastructure, increasing speed and weight of the rolling stock is necessary to ensure the stability of the subgrade on weak bases. LIRA software package allows you to perform all the necessary calculations for the selection of a proper way of strengthening weak bases.

  20. Nonlinear Waveforms for Ion-Acoustic Waves in Weakly Relativistic Plasma of Warm Ion-Fluid and Isothermal Electrons

    Directory of Open Access Journals (Sweden)

    S. A. El-Wakil

    2012-01-01

    Full Text Available The reductive perturbation method has been employed to derive the Korteweg-de Vries (KdV equation for small- but finite-amplitude electrostatic ion-acoustic waves in weakly relativistic plasma consisting of warm ions and isothermal electrons. An algebraic method with computerized symbolic computation is applied in obtaining a series of exact solutions of the KdV equation. Numerical studies have been made using plasma parameters which reveal different solutions, that is, bell-shaped solitary pulses, rational pulses, and solutions with singularity at finite points, which called “blowup” solutions in addition to the propagation of an explosive pulses. The weakly relativistic effect is found to significantly change the basic properties (namely, the amplitude and the width of the ion-acoustic waves. The result of the present investigation may be applicable to some plasma environments, such as ionosphere region.

  1. Pulse shaping with transmission lines

    Science.gov (United States)

    Wilcox, Russell B.

    1987-01-01

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  2. Coherent control of light-pulse propagation in a Raman induced grating

    Science.gov (United States)

    Arkhipkin, V. G.; Myslivets, S. A.

    2017-05-01

    We study light-pulse propagation in a dynamically controllable periodic structure (grating) resulting from Raman interaction of a weak probe pulse with a standing-wave pump and a second control laser field in N-type four-level atomic media. The grating is induced due to periodic spatial modulation of the Raman gain in a standing pump field (Raman gain grating). We show that it is possible to control both the probe pulse amplitude and the group velocity of the pulse from subluminal to superluminal by varying the pump or control field. Such a grating is of interest for all-optical switches and transistors.

  3. Laser Energy Monitor for Double-Pulsed 2-Micrometer IPDA Lidar Application

    Science.gov (United States)

    Refaat, Tamer F.; Petros, Mulugeta; Remus, Ruben; Yu, Jirong; Singh, Upendra N.

    2014-01-01

    Integrated path differential absorption (IPDA) lidar is a remote sensing technique for monitoring different atmospheric species. The technique relies on wavelength differentiation between strong and weak absorbing features normalized to the transmitted energy. 2-micron double-pulsed IPDA lidar is best suited for atmospheric carbon dioxide measurements. In such case, the transmitter produces two successive laser pulses separated by short interval (200 microseconds), with low repetition rate (10Hz). Conventional laser energy monitors, based on thermal detectors, are suitable for low repetition rate single pulse lasers. Due to the short pulse interval in double-pulsed lasers, thermal energy monitors underestimate the total transmitted energy. This leads to measurement biases and errors in double-pulsed IPDA technique. The design and calibration of a 2-micron double-pulse laser energy monitor is presented. The design is based on a high-speed, extended range InGaAs pin quantum detectors suitable for separating the two pulse events. Pulse integration is applied for converting the detected pulse power into energy. Results are compared to a photo-electro-magnetic (PEM) detector for impulse response verification. Calibration included comparing the three detection technologies in single-pulsed mode, then comparing the pin and PEM detectors in double-pulsed mode. Energy monitor linearity will be addressed.

  4. [Pulse oximetry in pediatric practice].

    Science.gov (United States)

    Brackel, H J; van Essen-Zandvliet, E E; de Jongste, J C; Kerrebijn, K F

    1990-02-01

    Pulse oximetry is a reliable technique for continuous, transcutaneous measurement of oxygen saturation and pulse frequency. Common indications for pulse oximetry in general pediatrics include: monitoring of oxygenation during an asthma attack, detection of apnea or hypoventilation, diagnosis of hypoxemia in patients with chronic respiratory insufficiency and monitoring of oxygen suppletion. In this article we discuss the various applications and limitations of pulse oximetry in clinical practice and describe a method to store, analyse and present pulse oximeter-results.

  5. The First Gauge Theory of Weak Interactions and the Prediction of Weak Neutral Currents

    OpenAIRE

    Bludman, S. A.

    1992-01-01

    The three theoretical and historical components of the Standard Model are the exact chiral gauge theory of weak interactions, electroweak unification, and the Higgs mechanism for spontaneous symmetry breaking. I put into historical perspective my 1958 invention of the first gauge theory of weak interactions, predicting weak neutral currents, and show how the fundamental differences between global and gauge symmetries and between partial flavour and exact gauge symmetries, emerged in the stron...

  6. Geometric phase topology in weak measurement

    Science.gov (United States)

    Samlan, C. T.; Viswanathan, Nirmal K.

    2017-12-01

    The geometric phase visualization proposed by Bhandari (R Bhandari 1997 Phys. Rep. 281 1–64) in the ellipticity-ellipse orientation basis of the polarization ellipse of light is implemented to understand the geometric aspects of weak measurement. The weak interaction of a pre-selected state, acheived via spin-Hall effect of light (SHEL), results in a spread in the polarization ellipticity (η) or ellipse orientation (χ) depending on the resulting spatial or angular shift, respectively. The post-selection leads to the projection of the η spread in the complementary χ basis results in the appearance of a geometric phase with helical phase topology in the η ‑ χ parameter space. By representing the weak measurement on the Poincaré sphere and using Jones calculus, the complex weak value and the geometric phase topology are obtained. This deeper understanding of the weak measurement process enabled us to explore the techniques’ capabilities maximally, as demonstrated via SHEL in two examples—external reflection at glass-air interface and transmission through a tilted half-wave plate.

  7. Effect of extremely weak pulsed magnetic field type Bemer 3000 on ratings of perceived exertion

    National Research Council Canada - National Science Library

    D Gazurek; K Spodaryk

    2008-01-01

    The aim of this study was to examine whether is an influence of the exposition on different inductions of magnetic fields on rating of perceived exertion during 10 min long standardised physical cycloergometer exercise...

  8. Quantum cryptography protocols robust against photon number splitting attacks for weak laser pulse implementations.

    Science.gov (United States)

    Scarani, Valerio; Acín, Antonio; Ribordy, Grégoire; Gisin, Nicolas

    2004-02-06

    We introduce a new class of quantum key distribution protocols, tailored to be robust against photon number splitting (PNS) attacks. We study one of these protocols, which differs from the original protocol by Bennett and Brassard (BB84) only in the classical sifting procedure. This protocol is provably better than BB84 against PNS attacks at zero error.

  9. Emission of strong Terahertz pulses from laser wakefields in weakly coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Divya, E-mail: dsingh@rajdhani.du.ac.in [PWAPA Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India); Department of Physics & Electronics, Rajdhani College, University of Delhi, Raja Garden, Ring Road, New Delhi 110015 (India); Malik, Hitendra K. [PWAPA Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India)

    2016-09-01

    The present paper discusses the laser plasma interaction for the wakefield excitation and the role of external magnetic field for the emission of Terahertz radiation in a collisional plasma. Flat top lasers are shown to be more appropriate than the conventional Gaussian lasers for the effective excitation of wakefields and hence, the generation of strong Terahertz radiation through the transverse component of wakefield.

  10. Effect of extremely weak pulsed magnetic field type Bemer 3000 on ratings of perceived exertion

    Directory of Open Access Journals (Sweden)

    D Gazurek

    2008-06-01

    Full Text Available The aim of this study was to examine whether is an influence of the exposition on different inductions of magnetic fields on rating of perceived exertion during 10 min long standardised physical cycloergometer exercise. The investigation was performed in 40 healthy, non-smoking, fit men, mean age 202. The participants were randomly attributed to 4 groups, each including 10 subjects. The first one (group E18 consisted of subjects exposed to the magnetic field with the intensity of 18 μT, the second one (group E64 exposed to the magnetic field with the intensity of 64 μT. Two control groups were formed to accompany these exposed to the magnetic field. In these placebo groups (S-T subjects were not exposed to the magnetic field (so called false therapy, „sham treatment”. The study consisted of 4 steps: pilot study, the first endurance test, exposure to the magnetic field, the second endurance test. The aim of the pilot study was to define subjective feelings of the participant during the effort, his reaction to the effort and also practical familiarization with the character and rules of the endurance test and Borg scale interpretation during 10 min of endurance cycloergometer test. The first endurance test was performed two days after the pilot study with the same rules and its goal was to measure the level of tiredness according to the Borg scale during 10 min long standardised physical effort. The second endurance test was performed according to the same rules as the first one and its goal was to analyse the effect of 20 exposures to the magnetic field with the intensity of 18 and 64 μT repeated daily on the perception of tiredness increase as expressed in the Borg scale when performing 10 min long standardised physical effort. In subjects exposed to 18 μT magnetic field neither changes in the perception of fatigue nor changes in the heart rate at particular levels of the Borg scale have been observed. When compared with both control and placebo group subjects exposed to 64 μT strong magnetic field exhibited statistically significant increase in the period of attaining consecutive levels of fatigue as measured in the Borg scale. Results of the present study demonstrated beneficial influence of the magnetic field with 64 μT intensity on changes in the perception of fatigue during physical workload.

  11. Lowering backward Raman and Brillouin scattering in waveguide Raman wavelength converters

    National Research Council Canada - National Science Library

    Phan Huy, Min Châu; Delaye, Philippe; Pauliat, Gilles; Dubreuil, Nicolas; Gérôme, Frédéric; Debord, Benoît; Benabid, Fetah; Lebrun, Sylvie

    2017-01-01

    .... However, and depending on the pulse duration, the optimization of Raman converters turns to be rather challenging since the desired forward Raman scattering may compete with counter-propagating...

  12. Weak KAM theory for a weakly coupled system of Hamilton–Jacobi equations

    KAUST Repository

    Figalli, Alessio

    2016-06-23

    Here, we extend the weak KAM and Aubry–Mather theories to optimal switching problems. We consider three issues: the analysis of the calculus of variations problem, the study of a generalized weak KAM theorem for solutions of weakly coupled systems of Hamilton–Jacobi equations, and the long-time behavior of time-dependent systems. We prove the existence and regularity of action minimizers, obtain necessary conditions for minimality, extend Fathi’s weak KAM theorem, and describe the asymptotic limit of the generalized Lax–Oleinik semigroup. © 2016, Springer-Verlag Berlin Heidelberg.

  13. Weak layer fracture: facets and depth hoar

    Directory of Open Access Journals (Sweden)

    I. Reiweger

    2013-09-01

    Full Text Available Understanding failure initiation within weak snow layers is essential for modeling and predicting dry-snow slab avalanches. We therefore performed laboratory experiments with snow samples containing a weak layer consisting of either faceted crystals or depth hoar. During these experiments the samples were loaded with different loading rates and at various tilt angles until fracture. The strength of the samples decreased with increasing loading rate and increasing tilt angle. Additionally, we took pictures of the side of four samples with a high-speed video camera and calculated the displacement using a particle image velocimetry (PIV algorithm. The fracture process within the weak layer could thus be observed in detail. Catastrophic failure started due to a shear fracture just above the interface between the depth hoar layer and the underlying crust.

  14. Pulse Propagation in a simple probabilistic transport model

    Energy Technology Data Exchange (ETDEWEB)

    van Milligen, B. Ph. [Asociacion EURATOM-CIEMAT; Carreras, Benjamin A [ORNL; Lynch, Vickie E [ORNL; Sanchez, Raul [ORNL

    2007-01-01

    The response to perturbations of a simplified transport model is studied. The model is used as a paradigmatic example of transport controlled by a critical gradient. Long-time system behavior is diffusive when most of the system is sub-critical. However, when the critical mechanism becomes significant, it is observed to dominate the system behavior at both short- and long-time scales. While the pulse amplitude decays in an approximately diffusive manner at long times for weakly critical situations, the pulse shape is not self-similar.

  15. Extrapolating Weak Selection in Evolutionary Games

    Science.gov (United States)

    Wu, Bin; García, Julián; Hauert, Christoph; Traulsen, Arne

    2013-01-01

    In evolutionary games, reproductive success is determined by payoffs. Weak selection means that even large differences in game outcomes translate into small fitness differences. Many results have been derived using weak selection approximations, in which perturbation analysis facilitates the derivation of analytical results. Here, we ask whether results derived under weak selection are also qualitatively valid for intermediate and strong selection. By “qualitatively valid” we mean that the ranking of strategies induced by an evolutionary process does not change when the intensity of selection increases. For two-strategy games, we show that the ranking obtained under weak selection cannot be carried over to higher selection intensity if the number of players exceeds two. For games with three (or more) strategies, previous examples for multiplayer games have shown that the ranking of strategies can change with the intensity of selection. In particular, rank changes imply that the most abundant strategy at one intensity of selection can become the least abundant for another. We show that this applies already to pairwise interactions for a broad class of evolutionary processes. Even when both weak and strong selection limits lead to consistent predictions, rank changes can occur for intermediate intensities of selection. To analyze how common such games are, we show numerically that for randomly drawn two-player games with three or more strategies, rank changes frequently occur and their likelihood increases rapidly with the number of strategies . In particular, rank changes are almost certain for , which jeopardizes the predictive power of results derived for weak selection. PMID:24339769

  16. Extrapolating weak selection in evolutionary games.

    Directory of Open Access Journals (Sweden)

    Bin Wu

    Full Text Available In evolutionary games, reproductive success is determined by payoffs. Weak selection means that even large differences in game outcomes translate into small fitness differences. Many results have been derived using weak selection approximations, in which perturbation analysis facilitates the derivation of analytical results. Here, we ask whether results derived under weak selection are also qualitatively valid for intermediate and strong selection. By "qualitatively valid" we mean that the ranking of strategies induced by an evolutionary process does not change when the intensity of selection increases. For two-strategy games, we show that the ranking obtained under weak selection cannot be carried over to higher selection intensity if the number of players exceeds two. For games with three (or more strategies, previous examples for multiplayer games have shown that the ranking of strategies can change with the intensity of selection. In particular, rank changes imply that the most abundant strategy at one intensity of selection can become the least abundant for another. We show that this applies already to pairwise interactions for a broad class of evolutionary processes. Even when both weak and strong selection limits lead to consistent predictions, rank changes can occur for intermediate intensities of selection. To analyze how common such games are, we show numerically that for randomly drawn two-player games with three or more strategies, rank changes frequently occur and their likelihood increases rapidly with the number of strategies [Formula: see text]. In particular, rank changes are almost certain for [Formula: see text], which jeopardizes the predictive power of results derived for weak selection.

  17. Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

    Science.gov (United States)

    Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

    2013-01-01

    A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

  18. A theoretical overview of hypernuclear weak decay

    Energy Technology Data Exchange (ETDEWEB)

    Chumillas, C. [Departament d' Estructura i Constituents de la Materia and Institut de Ciencies del Cosmos, Universitat de Barcelona, E-08028 Barcelona (Spain); Garbarino, G. [Dipartimento di Fisica Teorica, Universita di Torino and INFN, Sezione di Torino, I-10125 Torino (Italy)], E-mail: garbarin@to.infn.it; Parreno, A.; Ramos, A. [Departament d' Estructura i Constituents de la Materia and Institut de Ciencies del Cosmos, Universitat de Barcelona, E-08028 Barcelona (Spain)

    2008-05-15

    The physics of the weak decay of hypernuclei is briefly reviewed from a theoretical point of view. Special regard is devoted to the recent progress concerning the determination of the non-mesonic decay widths and the asymmetry parameters. Convincing evidence has been achieved for a solution of the long-standing puzzle on the ratio {gamma}{sub n}/{gamma}{sub p}. Very recently, it has been shown that the exchange of a {pi}{pi} pair in the weak mechanism plays a crucial role in explaining the discrepancies between theory and experiment on the decay asymmetries.

  19. Weak interactions at high energies. [Lectures, review

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, J.

    1978-08-01

    Review lectures are presented on the phenomenological implications of the modern spontaneously broken gauge theories of the weak and electromagnetic interactions, and some observations are made about which high energy experiments probe what aspects of gauge theories. Basic quantum chromodynamics phenomenology is covered including momentum dependent effective quark distributions, the transverse momentum cutoff, search for gluons as sources of hadron jets, the status and prospects for the spectroscopy of fundamental fermions and how fermions may be used to probe aspects of the weak and electromagnetic gauge theory, studies of intermediate vector bosons, and miscellaneous possibilities suggested by gauge theories from the Higgs bosons to speculations about proton decay. 187 references. (JFP)

  20. From Suitable Weak Solutions to Entropy Viscosity

    KAUST Repository

    Guermond, Jean-Luc

    2010-12-16

    This paper focuses on the notion of suitable weak solutions for the three-dimensional incompressible Navier-Stokes equations and discusses the relevance of this notion to Computational Fluid Dynamics. The purpose of the paper is twofold (i) to recall basic mathematical properties of the three-dimensional incompressible Navier-Stokes equations and to show how they might relate to LES (ii) to introduce an entropy viscosity technique based on the notion of suitable weak solution and to illustrate numerically this concept. © 2010 Springer Science+Business Media, LLC.

  1. A Continuation Method for Weakly Kannan Maps

    Directory of Open Access Journals (Sweden)

    Ariza-Ruiz David

    2010-01-01

    Full Text Available The first continuation method for contractive maps in the setting of a metric space was given by Granas. Later, Frigon extended Granas theorem to the class of weakly contractive maps, and recently Agarwal and O'Regan have given the corresponding result for a certain type of quasicontractions which includes maps of Kannan type. In this note we introduce the concept of weakly Kannan maps and give a fixed point theorem, and then a continuation method, for this class of maps.

  2. Pulsed welding plasma source

    Science.gov (United States)

    Knyaz'kov, A.; Pustovykh, O.; Verevkin, A.; Terekhin, V.; Shachek, A.; Tyasto, A.

    2016-04-01

    It is shown that in order to form the current pulse of a near rectangular shape, which provides conversion of the welding arc into a dynamic mode, it is rational to connect a forming element made on the basis of an artificial forming line in series to the welding DC circuit. The paper presents a diagram of a pulsed device for welding with a non-consumable electrode in argon which was developed using the forming element. The conversion of the arc into the dynamic mode is illustrated by the current and voltage oscillograms of the arc gap and the dynamic characteristic of the arc within the interval of one pulse generation time in the arc gap. The background current travels in the interpulse interval.

  3. Discharge pulse phenomenology

    Science.gov (United States)

    Frederickson, A. R.

    1985-01-01

    A model was developed which places radiation induced discharge pulse results into a unified conceptual framework. Only two phenomena are required to interpret all space and laboratory results: (1) radiation produces large electrostatic fields inside insulators via the trapping of a net space charge density; and (2) the electrostatic fields initiate discharge streamer plasmas similar to those investigated in high voltage electrical insulation materials; these streamer plasmas generate the pulsing phenomena. The apparent variability and diversity of results seen is an inherent feature of the plasma streamer mechanism acting in the electric fields which is created by irradiation of the dielectrics. The implications of the model are extensive and lead to constraints over what can be done about spacecraft pulsing.

  4. Two pulse recoupling

    Science.gov (United States)

    Khaneja, Navin; Kumar, Ashutosh

    2017-08-01

    The paper describes a family of novel recoupling pulse sequences in magic angle spinning (MAS) solid state NMR, called two pulse recoupling. These pulse sequences can be employed for both homonuclear and heteronuclear recoupling experiments and are robust to dispersion in chemical shifts and rf-inhomogeneity. The homonuclear pulse sequence consists of a building block (π)ϕ(π) - ϕ where ϕ =π/4n, and n is number of blocks in a rotor period. The recoupling block is made robust to rf-inhomogeneity by extending it to (π)ϕ(π) - ϕ(π) π + ϕ(π) π - ϕ . The heteronuclear recoupling pulse sequence consists of a building block (π)ϕ1(π)-ϕ1 and (π)ϕ2(π)-ϕ2 on channel I and S, where ϕ1 = 3π/8n, ϕ2 = π/8n and n is number of blocks in a rotor period. The recoupling block is made robust to rf-inhomogeneity by extending it to (π)ϕ1(π)-ϕ1(π) π +ϕ1(π) π -ϕ1 and (π)ϕ2(π)-ϕ2(π) π +ϕ2(π) π -ϕ2 on two channels respectively. The recoupling pulse sequences mix the z magnetization. Experimental quantification of this method is shown for 13Cα-13CO homonuclear recoupling in a sample of Glycine and 15N-13Cα heteronuclear recoupling in Alanine. Application of this method is demonstrated on a sample of tripeptide N-formyl-[U-13C,15N]-Met-Leu-Phe-OH (MLF). Compared to R-sequences (Levitt, 2002), these sequences are more robust to rf-inhomogeneity and give better sensitivity, as shown in Fig. 3.

  5. Highly Effective Crosstalk Mitigation Method Using Counter-Propagation in Semiconductor Optical Amplifier for Remodulation WDM-PONs

    Directory of Open Access Journals (Sweden)

    Quang Thai Pham

    2014-01-01

    Full Text Available Remodulation-induced crosstalk mitigation in WDM-PON using remodulation approach is presented in this paper. Utilizing all-optical signal processing, the proposed method has been able to significantly improve system performance in terms of bit error rate (BER and bit rate distance product. Moreover, the proposed method could be used for both baseband and modulated downstream electrical signals.

  6. Millimicrosecond pulse techniques

    CERN Document Server

    Lewis, Ian A D

    1959-01-01

    Millimicrosecond Pulse Techniques, Second Edition focuses on millimicrosecond pulse techniques and the development of devices of large bandwidth, extending down to comparatively low frequencies (1 Mc/s). Emphasis is on basic circuit elements and pieces of equipment of universal application. Specific applications, mostly in the field of nuclear physics instrumentation, are considered. This book consists of eight chapters and opens with an introduction to some of the terminology employed by circuit engineers as well as theoretical concepts, including the laws of circuit analysis, Fourier analysi

  7. Pulsed ESP handles AFBC

    Energy Technology Data Exchange (ETDEWEB)

    Larva, J.; Wilkomm, T.; Lugar, T.; Follett, R.E.

    1988-08-01

    The Black Dog 2 retrofit AFBC at Burnsville, Minnesota started coal firing in June 1986 using the units' existing precipitators for particulate control. The effects of various fuel blends, bed material, pulse power supplies and air atomized water injection flue gas conditioning were studied. The plant has been used for tests in the following areas: fired clay bed material, higher sulfur coal blends, ash recycle optimization, improved boiler operation, improved air heater thermal performance, improved rapper effectiveness, barbed wire electrodes, intermittent energization controls, pulse energization, and water injection. 4 refs., 4 figs., 1 tab.

  8. Pulse Doppler radar

    CERN Document Server

    Alabaster, Clive

    2012-01-01

    This book is a practitioner's guide to all aspects of pulse Doppler radar. It concentrates on airborne military radar systems since they are the most used, most complex, and most interesting of the pulse Doppler radars; however, ground-based and non-military systems are also included. It covers the fundamental science, signal processing, hardware issues, systems design and case studies of typical systems. It will be a useful resource for engineers of all types (hardware, software and systems), academics, post-graduate students, scientists in radar and radar electronic warfare sectors and milit

  9. Coherent and dynamic beam splitting based on light storage in cold atoms.

    Science.gov (United States)

    Park, Kwang-Kyoon; Zhao, Tian-Ming; Lee, Jong-Chan; Chough, Young-Tak; Kim, Yoon-Ho

    2016-09-28

    We demonstrate a coherent and dynamic beam splitter based on light storage in cold atoms. An input weak laser pulse is first stored in a cold atom ensemble via electromagnetically-induced transparency (EIT). A set of counter-propagating control fields, applied at a later time, retrieves the stored pulse into two output spatial modes. The high visibility interference between the two output pulses clearly demonstrates that the beam splitting process is coherent. Furthermore, by manipulating the control lasers, it is possible to dynamically control the storage time, the power splitting ratio, the relative phase, and the optical frequencies of the output pulses. With further improvements, the active beam splitter demonstrated in this work might have applications in photonic photonic quantum information and in all-optical information processing.

  10. Novel self-accelerating pulses generation via soliton pulses with cubic temporal phases in optical fibers

    Science.gov (United States)

    Zhong, Xianqiong; Yang, Ling; Cheng, Ke

    2017-11-01

    A novel self-accelerating pulse whose shape and spectrum consist of one main lobe and a series of weak decayed side ones is revealed numerically by a hyperbolic-secant soliton pulse with the cubic temporal phase (CTP). This novel self-accelerating pulse is somewhat similar to but never the same as the Airy one. The temporal main lobe is approximate sectioned parabolic curve and its bending direction may change more than once. Depending on different CTPs and soliton orders, the temporal trajectory bending directions, bending angles, bending ranges, bending times, and the concrete trajectory routes are also different. Depending on different CTPs, the spectra may be red- or blue-shifted. For the larger soliton order case, the spectral main lobe may vary its position. The results enable us to engineer the temporal trajectories and the corresponding spectra of the soliton pulses via introducing appropriate CTPs besides the conventional cubic spectral ones. Besides, the soliton order can be an auxiliary control parameter which can compress or stretch some of the temporal lobes.

  11. Studying dark matter haloes with weak lensing

    NARCIS (Netherlands)

    Velander, Malin Barbro Margareta

    2012-01-01

    Our Universe is comprised not only of normal matter but also of unknown components: dark matter and dark energy. This Thesis recounts studies of dark matter haloes, using a technique known as weak gravitational lensing, in order to learn more about the nature of these dark components. The haloes

  12. Common fixed points for weakly compatible maps

    Indian Academy of Sciences (India)

    The purpose of this paper is to prove a common fixed point theorem, from the class of compatible continuous maps to a larger class of maps having weakly compatible maps without appeal to continuity, which generalized the results of Jungck [3], Fisher [1], Kang and Kim [8], Jachymski [2], and Rhoades [9].

  13. Quantum mechanical calculations on weakly interacting complexes

    NARCIS (Netherlands)

    Heijmen, T.G.A.

    1998-01-01

    Symmetry-adapted perturbation theory (SAPT) has been applied to compute the intermolecular potential energy surfaces and the interaction-induced electrical properties of weakly interacting complexes. Asymptotic (large R) expressions have been derived for the contributions to the collision-induced

  14. Cultural capital: strengths, weaknesses and two advancements

    NARCIS (Netherlands)

    van de Werfhorst, H.G.

    2010-01-01

    In this paper I discuss two weaknesses in Bourdieu’s work on cultural capital, both of which are related to his integration of the multidimensional nature of social space in different domains of life: social mobility, lifestyle differentiation, and political orientation. First, there is an anomaly

  15. Reducing Weak to Strong Bisimilarity in CCP

    Directory of Open Access Journals (Sweden)

    Andrés Aristizábal

    2012-12-01

    Full Text Available Concurrent constraint programming (ccp is a well-established model for concurrency that singles out the fundamental aspects of asynchronous systems whose agents (or processes evolve by posting and querying (partial information in a global medium. Bisimilarity is a standard behavioural equivalence in concurrency theory. However, only recently a well-behaved notion of bisimilarity for ccp, and a ccp partition refinement algorithm for deciding the strong version of this equivalence have been proposed. Weak bisimiliarity is a central behavioural equivalence in process calculi and it is obtained from the strong case by taking into account only the actions that are observable in the system. Typically, the standard partition refinement can also be used for deciding weak bisimilarity simply by using Milner's reduction from weak to strong bisimilarity; a technique referred to as saturation. In this paper we demonstrate that, because of its involved labeled transitions, the above-mentioned saturation technique does not work for ccp. We give an alternative reduction from weak ccp bisimilarity to the strong one that allows us to use the ccp partition refinement algorithm for deciding this equivalence.

  16. Thermorheological effect on magnetoconvection in weak electrically ...

    Indian Academy of Sciences (India)

    Abstract. The thermorheological effect on magnetoconvection in fluids with weak elec- trical conductivity is studied numerically under 1g and μg conditions. The results with a non-linear thermorheological equation considered in the problem when compared with those of the classical approach with constant viscosity ...

  17. Solitons and Weakly Nonlinear Waves in Plasmas

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1985-01-01

    Theoretical descriptions of solitons and weakly nonlinear waves propagating in plasma media are reviewed, with particular attention to the Korteweg-de Vries (KDV) equation and the Nonlinear Schrödinger equation (NLS). The modifications of these basic equations due to the effects of resonant...

  18. Fermi and the Theory of Weak Interactions

    Indian Academy of Sciences (India)

    IAS Admin

    The history of weak interactions starting with. Fermi's creation of the beta decay theory and culminating in its modern avatar in the form of the electroweak gauge theory is described. Dis- coveries of parity violation, matter{antimatter asymmetry, W and Z bosons and neutrino mass are highlighted. Introduction. Sun gives us ...

  19. Phenomenological model of the weak interaction

    OpenAIRE

    Schunck, Franz E.

    2008-01-01

    We use the informations known so far about elementary particles in order to construct a simple model. We find a reason for the gyromagnetic factor of 2 for leptons and a vivid imagination for the weak interaction. By this, we understand, why the elementary particles with lowest mass are stable and all other unstable.

  20. Fermi and the Theory of Weak Interactions

    OpenAIRE

    Rajasekaran, G.

    2014-01-01

    The history of weak interactions starting with Fermi's creation of the beta decay theory and culminating in its modern avatar in the form of the electroweak gauge theory is described. Discoveries of parity violation, matter-antimatter asymmetry, W and Z bosons and neutrino mass are highlighted.

  1. Dynamical theory of weak and electromagnetic interactions

    CERN Document Server

    Englert, F

    1974-01-01

    The gauge theory of unified weak and electromagnetic interactions is developed without the use of scalar mesons. It is shown that the Glashow Weinberg scheme is unrealistic, but that a similar such scheme is possible if one includes two pairs of leptons, identified with e-, νe and μ-, νμ.

  2. The weak acid nature of precipitation

    Science.gov (United States)

    John O. Frohliger; Robert L. Kane

    1976-01-01

    Recent measurements of the pH of precipitation leave no doubt that rainfall is acidic. Evidence will be presented that precipitation is a weak acid system. The results of this research indicate the need to establish standard sampling procedures to provide uniform sampling of precipitation

  3. Neutrino propagation in a weakly magnetized medium

    Indian Academy of Sciences (India)

    of the W and Z bosons allowing us to neglect the momentum dependence in the. W and Z propagators. This is equivalent to lowest-order GF calculations and is justified for low-energy neutrinos and low temperatures and weak fields compared to the Fermi scale. Since, in this work we focus our attention on the possible astro ...

  4. Fermi and the Theory of Weak Interactions

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 1. Fermi and the Theory of Weak Interactions. G Rajasekaran. General Article Volume 19 Issue 1 January 2014 pp 18-44 ... Keywords. Fermi; beta decay; parity violation; electroweak theory; neutral current; quarks and leptons; neutrino mass.

  5. Weak organic acid stress in Bacillus subtilis

    NARCIS (Netherlands)

    ter Beek, A.S.

    2009-01-01

    Weak organic acids are commonly used food preservatives that protect food products from bacterial contamination. A variety of spore-forming bacterial species pose a serious problem to the food industry by causing extensive food spoilage or even food poisoning. Understanding the mechanisms of

  6. SNMR pulse sequence phase cycling

    Science.gov (United States)

    Walsh, David O; Grunewald, Elliot D

    2013-11-12

    Technologies applicable to SNMR pulse sequence phase cycling are disclosed, including SNMR acquisition apparatus and methods, SNMR processing apparatus and methods, and combinations thereof. SNMR acquisition may include transmitting two or more SNMR pulse sequences and applying a phase shift to a pulse in at least one of the pulse sequences, according to any of a variety cycling techniques. SNMR processing may include combining SNMR from a plurality of pulse sequences comprising pulses of different phases, so that desired signals are preserved and indesired signals are canceled.

  7. Optogenetic light pulses generator

    Science.gov (United States)

    Erofeev, A. I.; Matveev, M. V.; Zakharova, O. A.; Terekhin, S. G.; Kilimnik, V. A.; Bezprozvanny, I. B.; Vlasova, O. L.

    2017-11-01

    To date, optogenetics is one of the most popular methods in the world in neuroscience. There are new equipment and devices created to keep the progress of this method. This article describes a light pulse generator developed at the Laboratory of Molecular Neurodegeneration, designed for optogenetic experiments.

  8. Pulsed electric fields

    Science.gov (United States)

    The concept of pulsed electric fields (PEF) was first proposed in 1967 to change the behavior or microorganisms. The electric field phenomenon was identified as membrane rupture theory in the 1980s. Increasing the membrane permeability led to the application of PEF assisted extraction of cellular co...

  9. Efficient calculation of the polarization induced by N coherent laser pulses.

    Science.gov (United States)

    Gelin, Maxim F; Egorova, Dassia; Domcke, Wolfgang

    2009-11-21

    We have developed a novel method, the equation-of-motion phase-matching approach (EOM-PMA), for the calculation of the response of a quantum system to N coherent laser fields. The N-pulse EOM-PMA is limited to weak fields (its domain of validity is equivalent to the traditional nonlinear response functions approach), but allows for arbitrary pulse durations and automatically accounts for pulse-overlap effects. The N-pulse EOM-PMA allows the evaluation of the time evolution of the N-pulse-induced polarization in any phase-matching direction by performing 2(N)-1 independent propagations of certain auxiliary density matrices. The N-pulse EOM-PMA can straightforwardly be incorporated into codes which provide the time evolution of the density matrix of material systems of interest and can efficiently be implemented on parallel computers.

  10. Long-time Integration of a Multi-waveform for Weak Target Detectcion in Non-cooperative Passive Bistatic Radar

    Directory of Open Access Journals (Sweden)

    Qian Lichang

    2017-06-01

    Full Text Available Space, time, and phase synchronization problems make weak target detection evenmore difficult in the Non-cooperative Passive Bistatic Radar (NPBR than in conventional radar systems. Therefore, a time and phase synchronization method based on direct waveform parameter estimation and a weak target detection method based on long time coherent integration of a multi-waveform is presented in this paper. First, a universal pulse extraction method based on differential sequence indexing is proposed. Second, an estimation method for the direct waveform parameters, including pulse width, pulse repetition intervals, bandwidth, carrier frequency, and arrival time, is provided. Therefore, by using the estimated waveform parameters, the NPBR time and phase synchronization can be realized. Moreover, based on the waveform parameter estimation, a weak target detection method based on the generalized Radon-Fourier transform of a multi-waveform is provided. Finally, simulation and real data experiments for verifying the effectiveness of the waveform parameter estimation and weak target detection methods are provided.

  11. A compact nanosecond pulse modulator

    Science.gov (United States)

    Sha, Jizhang; Xue, Jianchao; Qiang, Bohan

    Two circuits of nanosecond pulse modulator which generate two different width rectangular pulses respectively are described. The basic configuration of the modulator is the Marx circuit, in which avalanche transistors are used as switching devices. In order to obtain the rectangular pulses a pulse-forming network (PFN) is introduced and fitted into the Marx. A multi-parallel arrangement of the Marx is used to satisfy the broad pulse requirement. Experiments have shown that the two different width rectangular pulses which have 130 V amplitudes and 30 and 200 ns widths respectively can be obtained at a 50 ohms load. The two pulses have steep front edges (3.6 ns and 10 ns respectively) and flat tops with less than + or - 5 percent ripples. Therefore, the modulator can meet the requirements of the nanosecond pulse radar.

  12. Wide spectrum microwave pulse measurement

    Energy Technology Data Exchange (ETDEWEB)

    King, R.J.

    1986-01-01

    Various techniques are postulated as diagnostics for wide band microwave pulses. The diagnostics include determinations of both the instantaneous amplitude and the frequency content of one-shot pulses. 6 refs., 11 figs. (WRF)

  13. Weak localization of light in ZnO nanorods in space and time

    Energy Technology Data Exchange (ETDEWEB)

    Mascheck, Manfred; Schmidt, Slawa; Silies, Martin; Lienau, Christoph [Carl von Ossietzky Universitaet, Oldenburg (Germany); Leipold, David; Runge, Erich [Technische Universitaet, Ilmenau (Germany); Yatsui, Takashi; Kitamura, Kokoro; Ohtsu, Motoichi [University of Tokyo (Japan)

    2011-07-01

    An array of ZnO nanorods is used to directly visualize the weak localization of light in both space and time. Ultrashort laser pulses from a Ti:Sapphire oscillator with a pulse duration of 6 fs are focused to their diffraction-limit of 1 {mu}m{sup 2} onto the ZnO nanorod array using an all-reflective Cassegrain objective. The generated SH emission is collected in reflection geometry and detected as a function of the lateral position of the laser focus. Pronounced intensity fluctuations on a sub-{mu}m scale due to the multiple random scattering inside the nanoneedle array are taken as the spatial hallmark of weak the localization of light. By varying the delay between the phase-stabilized pair of laser pulses from a dispersion-balanced Michelson interferometer, interferometric frequency-resolved autocorrelation (IFRAC) traces are measured. By analyzing these traces in the frequency domain, the dephasing time and therewith the temporal evolution of the electric field within the ZnO array could be deduced.

  14. New weak keys in simplified IDEA

    Science.gov (United States)

    Hafman, Sari Agustini; Muhafidzah, Arini

    2016-02-01

    Simplified IDEA (S-IDEA) is simplified version of International Data Encryption Algorithm (IDEA) and useful teaching tool to help students to understand IDEA. In 2012, Muryanto and Hafman have found a weak key class in the S-IDEA by used differential characteristics in one-round (0, ν, 0, ν) → (0,0, ν, ν) on the first round to produce input difference (0,0, ν, ν) on the fifth round. Because Muryanto and Hafman only use three differential characteristics in one-round, we conducted a research to find new differential characteristics in one-round and used it to produce new weak key classes of S-IDEA. To find new differential characteristics in one-round of S-IDEA, we applied a multiplication mod 216+1 on input difference and combination of active sub key Z1, Z4, Z5, Z6. New classes of weak keys are obtained by combining all of these characteristics and use them to construct two new differential characteristics in full-round of S-IDEA with or without the 4th round sub key. In this research, we found six new differential characteristics in one round and combined them to construct two new differential characteristics in full-round of S-IDEA. When two new differential characteristics in full-round of S-IDEA are used and the 4th round sub key required, we obtain 2 new classes of weak keys, 213 and 28. When two new differential characteristics in full-round of S-IDEA are used, yet the 4th round sub key is not required, the weak key class of 213 will be 221 and 28 will be 210. Membership test can not be applied to recover the key bits in those weak key classes. The recovery of those unknown key bits can only be done by using brute force attack. The simulation result indicates that the bit of the key can be recovered by the longest computation time of 0,031 ms.

  15. Sequentially pulsed traveling wave accelerator

    Science.gov (United States)

    Caporaso, George J [Livermore, CA; Nelson, Scott D [Patterson, CA; Poole, Brian R [Tracy, CA

    2009-08-18

    A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

  16. Bacterial inactivation using pulsed light

    OpenAIRE

    Elmnasser, Noura; Ritz, Magali; Leroi, Francoise; Orange, Nicole; Bakhrouf, Amina; Federighi, Michel

    2007-01-01

    Pulsed light is a new method intended for the decontamination of food surfaces using short, high frequency pulses of an intense broad spectrum. The effects of broad spectrum pulsed light on the survival of Listeria monocytogenes Scott A, Listeria monocytogenes CNL, Pseudomonas fluorescens MF37 and Photobacterium phosphoreum SF680 populations on agar and in a liquid medium were investigated during this study. The sterilisation system generated 1.5 J cm(-2) per pulse with eight lamps for 300 mu...

  17. Phase metrology with multi-cycle two-colour pulses

    Science.gov (United States)

    Petersson, C. L. M.; Carlström, S.; Schafer, K. J.; Mauritsson, J.

    2016-05-01

    Strong-field phenomena driven by an intense infrared (IR) laser depend on during what part of the field cycle they are initiated. By changing the sub-cycle character of the laser electric field it is possible to control such phenomena. For long pulses, sub-cycle shaping of the field can be done by adding a relatively weak, second harmonic of the driving field to the pulse. Through constructive and destructive interference, the combination of strong and weak fields can be used to change the probability of a strong-field process being initiated at any given part of the cycle. In order to control sub-cycle phenomena with optimal accuracy, it is necessary to know the phase difference of the strong and the weak fields precisely. If the weaker field is an even harmonic of the driving field, electrons ionized by the field will be asymmetrically distributed between the positive and negative directions of the combined fields. Information about the asymmetry can yield information about the phase difference. A technique to measure asymmetry for few-cycle pulses, called stereo-ATI (above threshold ionization), has been developed by Paulus et al (2003 Phys. Rev. Lett. 91 253004). This paper outlines an extension of this method to measure the phase difference between a strong IR and its second harmonic.

  18. Quantum Groups, Property (T), and Weak Mixing

    Science.gov (United States)

    Brannan, Michael; Kerr, David

    2017-11-01

    For second countable discrete quantum groups, and more generally second countable locally compact quantum groups with trivial scaling group, we show that property (T) is equivalent to every weakly mixing unitary representation not having almost invariant vectors. This is a generalization of a theorem of Bekka and Valette from the group setting and was previously established in the case of low dual by Daws, Skalski, and Viselter. Our approach uses spectral techniques and is completely different from those of Bekka-Valette and Daws-Skalski-Viselter. By a separate argument we furthermore extend the result to second countable nonunimodular locally compact quantum groups, which are shown in particular not to have property (T), generalizing a theorem of Fima from the discrete setting. We also obtain quantum group versions of characterizations of property (T) of Kerr and Pichot in terms of the Baire category theory of weak mixing representations and of Connes and Weiss in terms of the prevalence of strongly ergodic actions.

  19. Model Reduction of Strong-Weak Neurons

    Directory of Open Access Journals (Sweden)

    Steven James Cox

    2014-12-01

    Full Text Available We consider neurons with large dendritic trees that are weakly excitable in the sense that back propagating action potentials are severly attenuated as they travelfrom the small, strongly excitable, spike initiation zone. In previous workwe have shown that the computational size of weakly excitable cell modelsmay be reduced by two or more orders of magnitude, and that the size of stronglyexcitable models may be reduced by at least one order of magnitude,without sacrificing thespatio-temporal nature of its inputs (in the sense we reproduce the cell's precise mapping of inputs to outputs. We combine the best of these twostrategies via a predictor--corrector decomposition scheme andachieve a drastically reduced highly accurate model of a caricature of the neuron responsible for collision detection in the locust.

  20. Model reduction of strong-weak neurons.

    Science.gov (United States)

    Du, Bosen; Sorensen, Danny; Cox, Steven J

    2014-01-01

    We consider neurons with large dendritic trees that are weakly excitable in the sense that back propagating action potentials are severly attenuated as they travel from the small, strongly excitable, spike initiation zone. In previous work we have shown that the computational size of weakly excitable cell models may be reduced by two or more orders of magnitude, and that the size of strongly excitable models may be reduced by at least one order of magnitude, without sacrificing the spatio-temporal nature of its inputs (in the sense we reproduce the cell's precise mapping of inputs to outputs). We combine the best of these two strategies via a predictor-corrector decomposition scheme and achieve a drastically reduced highly accurate model of a caricature of the neuron responsible for collision detection in the locust.

  1. Towards weakly constrained double field theory

    Directory of Open Access Journals (Sweden)

    Kanghoon Lee

    2016-08-01

    Full Text Available We show that it is possible to construct a well-defined effective field theory incorporating string winding modes without using strong constraint in double field theory. We show that X-ray (Radon transform on a torus is well-suited for describing weakly constrained double fields, and any weakly constrained fields are represented as a sum of strongly constrained fields. Using inverse X-ray transform we define a novel binary operation which is compatible with the level matching constraint. Based on this formalism, we construct a consistent gauge transform and gauge invariant action without using strong constraint. We then discuss the relation of our result to the closed string field theory. Our construction suggests that there exists an effective field theory description for massless sector of closed string field theory on a torus in an associative truncation.

  2. Weak Gravitational Lensing of Finite Beams

    Science.gov (United States)

    Fleury, Pierre; Larena, Julien; Uzan, Jean-Philippe

    2017-11-01

    The standard theory of weak gravitational lensing relies on the infinitesimal light beam approximation. In this context, images are distorted by convergence and shear, the respective sources of which unphysically depend on the resolution of the distribution of matter—the so-called Ricci-Weyl problem. In this Letter, we propose a strong-lensing-inspired formalism to describe the lensing of finite beams. We address the Ricci-Weyl problem by showing explicitly that convergence is caused by the matter enclosed by the beam, regardless of its distribution. Furthermore, shear turns out to be systematically enhanced by the finiteness of the beam. This implies, in particular, that the Kaiser-Squires relation between shear and convergence is violated, which could have profound consequences on the interpretation of weak-lensing surveys.

  3. On Uniform Weak König's Lemma

    DEFF Research Database (Denmark)

    Kohlenbach, Ulrich

    2002-01-01

    The so-called weak Konig's lemma WKL asserts the existence of an infinite path b in any infinite binary tree (given by a representing function f). Based on this principle one can formulate subsystems of higher-order arithmetic which allow to carry out very substantial parts of classical mathematics...... is of interest in the context of explicit mathematics as developed by S. Feferman. The elimination process in Kohlenbach [10] actually can be used to eliminate even this uniform weak Konig's lemma provided that PRA only has a quantifier-free rule of extensionality QF-ER instead of the full axioms (E...... as the computational strength of UWKL relative to the intuitionistic variant of PRA both with and without the Markov principle....

  4. Weak mixing angle measurements at hadron colliders

    CERN Document Server

    Di Simone, Andrea; The ATLAS collaboration

    2015-01-01

    The Talk will cover weak mixing angle measurements at hadron colliders ATLAS and CMS in particular. ATLAS has measured the forward-backward asymmetry for the neutral current Drell Yan process in a wide mass range around the Z resonance region using dielectron and dimuon final states with $\\sqrt{s}$ =7 TeV data. For the dielectron channel, the measurement includes electrons detected in the forward calorimeter which extends the covered phase space. The result is then used to extract a measurement of the effective weak mixing angle. Uncertainties from the limited knowledge on the parton distribution functions in the proton constitute a significant part of the uncertainty and a dedicated study is performed to obtain a PDF set describing W and Z data measured previously by ATLAS. Similar studies from CMS will be reported.

  5. The regularization of Old English weak verbs

    Directory of Open Access Journals (Sweden)

    Marta Tío Sáenz

    2015-07-01

    Full Text Available This article deals with the regularization of non-standard spellings of the verbal forms extracted from a corpus. It addresses the question of what the limits of regularization are when lemmatizing Old English weak verbs. The purpose of such regularization, also known as normalization, is to carry out lexicological analysis or lexicographical work. The analysis concentrates on weak verbs from the second class and draws on the lexical database of Old English Nerthus, which has incorporated the texts of the Dictionary of Old English Corpus. As regards the question of the limits of normalization, the solution adopted are, in the first place, that when it is necessary to regularize, normalization is restricted to correspondences based on dialectal and diachronic variation and, secondly, that normalization has to be unidirectional.

  6. Asymptotic theory of weakly dependent random processes

    CERN Document Server

    Rio, Emmanuel

    2017-01-01

    Presenting tools to aid understanding of asymptotic theory and weakly dependent processes, this book is devoted to inequalities and limit theorems for sequences of random variables that are strongly mixing in the sense of Rosenblatt, or absolutely regular. The first chapter introduces covariance inequalities under strong mixing or absolute regularity. These covariance inequalities are applied in Chapters 2, 3 and 4 to moment inequalities, rates of convergence in the strong law, and central limit theorems. Chapter 5 concerns coupling. In Chapter 6 new deviation inequalities and new moment inequalities for partial sums via the coupling lemmas of Chapter 5 are derived and applied to the bounded law of the iterated logarithm. Chapters 7 and 8 deal with the theory of empirical processes under weak dependence. Lastly, Chapter 9 describes links between ergodicity, return times and rates of mixing in the case of irreducible Markov chains. Each chapter ends with a set of exercises. The book is an updated and extended ...

  7. Shock Wave Dynamics in Weakly Ionized Plasmas

    Science.gov (United States)

    Johnson, Joseph A., III

    1999-01-01

    An investigation of the dynamics of shock waves in weakly ionized argon plasmas has been performed using a pressure ruptured shock tube. The velocity of the shock is observed to increase when the shock traverses the plasma. The observed increases cannot be accounted for by thermal effects alone. Possible mechanisms that could explain the anomalous behavior include a vibrational/translational relaxation in the nonequilibrium plasma, electron diffusion across the shock front resulting from high electron mobility, and the propagation of ion-acoustic waves generated at the shock front. Using a turbulence model based on reduced kinetic theory, analysis of the observed results suggest a role for turbulence in anomalous shock dynamics in weakly ionized media and plasma-induced hypersonic drag reduction.

  8. Orbits in weak and strong bars

    CERN Document Server

    Contopoulos, George

    1980-01-01

    The authors study the plane orbits in simple bar models embedded in an axisymmetric background when the bar density is about 1% (weak), 10% (intermediate) or 100% (strong bar) of the axisymmetric density. Most orbits follow the stable periodic orbits. The basic families of periodic orbits are described. In weak bars with two Inner Lindblad Resonances there is a family of stable orbits extending from the center up to the Outer Lindblad Resonance. This family contains the long period orbits near corotation. Other stable families appear between the Inner Lindblad Resonances, outside the Outer Lindblad Resonance, around corotation (short period orbits) and around the center (retrograde). Some families become unstable or disappear in strong bars. A comparison is made with cases having one or no Inner Lindblad Resonance. (12 refs).

  9. Weakly Collisional and Collisionless Astrophysical Plasmas

    DEFF Research Database (Denmark)

    Berlok, Thomas

    investigate helium mixing in the weakly collisional intracluster medium of galaxy clusters using Braginskii MHD. Secondly, we present a newly developed Vlasov-fluid code which can be used for studying fully collisionless plasmas such as the solar wind and hot accretions flows. The equations of Braginskii MHD...... are used to study weakly collisional, stratified atmospheres which offer a useful model of the intracluster medium of galaxy clusters. Using linear theory and computer simulations, we study instabilities that feed off thermal and compositional gradients. We find that these instabilities lead to vigorous...... mixing of the composition and discuss the potential consequences for X-ray observations of galaxy clusters. Collisionless plasmas can be subject to microscale velocity-space instabilities which are not well-described by Braginskii MHD. In contrast, Vlasov-fluid theory captures all the kinetic phenomena...

  10. A dynamical weak scale from inflation

    Science.gov (United States)

    You, Tevong

    2017-09-01

    Dynamical scanning of the Higgs mass by an axion-like particle during inflation may provide a cosmological component to explaining part of the hierarchy problem. We propose a novel interplay of this cosmological relaxation mechanism with inflation, whereby the backreaction of the Higgs vacuum expectation value near the weak scale causes inflation to end. As Hubble drops, the relaxion's dissipative friction increases relative to Hubble and slows it down enough to be trapped by the barriers of its periodic potential. Such a scenario raises the natural cut-off of the theory up to ~ 1010 GeV, while maintaining a minimal relaxion sector without having to introduce additional scanning scalars or new physics coincidentally close to the weak scale.

  11. A photodiode amplifier system for pulse-by-pulse intensity measurement of an x-ray free electron laser.

    Science.gov (United States)

    Kudo, Togo; Tono, Kensuke; Yabashi, Makina; Togashi, Tadashi; Sato, Takahiro; Inubushi, Yuichi; Omodani, Motohiko; Kirihara, Yoichi; Matsushita, Tomohiro; Kobayashi, Kazuo; Yamaga, Mitsuhiro; Uchiyama, Sadayuki; Hatsui, Takaki

    2012-04-01

    We have developed a single-shot intensity-measurement system using a silicon positive-intrinsic-negative (PIN) photodiode for x-ray pulses from an x-ray free electron laser. A wide dynamic range (10(3)-10(11) photons/pulse) and long distance signal transmission (>100 m) were required for this measurement system. For this purpose, we developed charge-sensitive and shaping amplifiers, which can process charge pulses with a wide dynamic range and variable durations (ns-μs) and charge levels (pC-μC). Output signals from the amplifiers were transmitted to a data acquisition system through a long cable in the form of a differential signal. The x-ray pulse intensities were calculated from the peak values of the signals by a waveform fitting procedure. This system can measure 10(3)-10(9) photons/pulse of ~10 keV x-rays by direct irradiation of a silicon PIN photodiode, and from 10(7)-10(11) photons/pulse by detecting the x-rays scattered by a diamond film using the silicon PIN photodiode. This system gives a relative accuracy of ~10(-3) with a proper gain setting of the amplifiers for each measurement. Using this system, we succeeded in detecting weak light at the developmental phase of the light source, as well as intense light during lasing of the x-ray free electron laser. © 2012 American Institute of Physics

  12. On weakly D-differentiable operators

    DEFF Research Database (Denmark)

    Christensen, Erik

    2016-01-01

    Let DD be a self-adjoint operator on a Hilbert space HH and aa a bounded operator on HH. We say that aa is weakly DD-differentiable, if for any pair of vectors ξ,ηξ,η from HH the function 〈eitDae−itDξ,η〉〈eitDae−itDξ,η〉 is differentiable. We give an elementary example of a bounded operator aa...

  13. Dynamic properties of superconducting weak links

    Science.gov (United States)

    Schmid, Albert; Schön, Gerd; Tinkham, Michael

    1980-06-01

    A comprehensive theoretical picture of the dynamic properties of the order parameter and the quasiparticles in superconducting short weak links is presented. Both diffusion and inelastic scattering are found to be important in relaxing nonequilibrium populations. At low voltages a dissipative current, which is considerably larger than the normal ohmic current, is found and at higher voltages the maximum supercurrent is enhanced. These effects describe quantitatively well the foot structure in the I-V characteristic observed experimentally by Octavio, Skocpol, and Tinkham.

  14. On weak compactness in L_1 spaces

    Czech Academy of Sciences Publication Activity Database

    Fabian, Marián; Montesinos, V.; Zizler, Václav

    2009-01-01

    Roč. 39, č. 6 (2009), s. 1885-1893 ISSN 0035-7596 R&D Projects: GA AV ČR(CZ) IAA100190610; GA AV ČR IAA100190502; GA AV ČR IAA1019103 Institutional research plan: CEZ:AV0Z10190503 Keywords : weak compactness * subspace of L_1 * superreflexive space Subject RIV: BA - General Mathematics Impact factor: 0.260, year: 2009

  15. Summary of the Hadronic Weak Interaction session

    Science.gov (United States)

    Bock, G.; Bryman, D. A.; Numao, T.

    1993-07-01

    We summarize and discuss present and future experiments on decays of light mesons and muons that were presented in the Hadronic Weak Interaction working group session of the Workshop on Future Directions in Particle and Nuclear Physics at Multi-GeV Hadron Facilities. Precise measurements and rare-decay searches, which sense mass scales in the 1-1000 TeV region, are discussed in the context of the standard model and beyond.

  16. Summary of the Hadronic Weak Interaction session

    Energy Technology Data Exchange (ETDEWEB)

    Bock, G. [Fermi National Accelerator Lab., Batavia, IL (United States); Bryman, D.A.; Numao, T. [British Columbia Univ., Vancouver, BC (Canada). TRIUMF Facility

    1993-07-01

    We summarize and discuss present and future experiments on decays of light mesons and muons that were presented in the Hadronic Weak Interaction working group session of the ``Workshop on Future Directions in Particle and Nuclear Physics at Multi-GeV Hadron Facilities.`` Precise measurements and rare-decay searches, which sense mass scales in the 1--1000 TeV region, are discussed in the context of the standard model and beyond.

  17. Diffusion in a weakly random Hamiltonian flow

    OpenAIRE

    Komorowski, T.; Ryzhik, L.

    2005-01-01

    We consider the motion of a particle governed by a weakly random Hamiltonian flow. We identify temporal and spatial scales on which the particle trajectory converges to a spatial Brownian motion. The main technical issue in the proof is to obtain error estimates for the convergence of the solution of the stochastic acceleration problem to a momentum diffusion. We also apply our results to the system of random geometric acoustics equations and show that the energy density of the acoustic waves...

  18. Ultrashort Optical Pulse Propagation in terms of Analytic Signal

    Directory of Open Access Journals (Sweden)

    Sh. Amiranashvili

    2011-01-01

    Full Text Available We demonstrate that ultrashort optical pulses propagating in a nonlinear dispersive medium are naturally described through incorporation of analytic signal for the electric field. To this end a second-order nonlinear wave equation is first simplified using a unidirectional approximation. Then the analytic signal is introduced, and all nonresonant nonlinear terms are eliminated. The derived propagation equation accounts for arbitrary dispersion, resonant four-wave mixing processes, weak absorption, and arbitrary pulse duration. The model applies to the complex electric field and is independent of the slowly varying envelope approximation. Still the derived propagation equation posses universal structure of the generalized nonlinear Schrödinger equation (NSE. In particular, it can be solved numerically with only small changes of the standard split-step solver or more complicated spectral algorithms for NSE. We present exemplary numerical solutions describing supercontinuum generation with an ultrashort optical pulse.

  19. Francium Spectroscopy for Weak Interaction Studies

    Science.gov (United States)

    Orozco, Luis

    2014-05-01

    Francium, a radioactive element, is the heaviest alkali. Its atomic and nuclear structure makes it an ideal laboratory to study the weak interaction. Laser trapping and cooling in-line with the superconducting LINAC accelerator at Stony Brook opened the precision study of its atomic structure. I will present our proposal and progress towards weak interaction measurements at TRIUMF, the National Canadian Accelerator in Vancouver. These include the commissioning run of the Francium Trapping Facility, hyperfine anomaly measurements on a chain of Fr isotopes, the nuclear anapole moment through parity non-conserving transitions in the ground state hyperfine manifold. These measurements should shed light on the nucleon-nucleon weak interaction. This work is done by the FrPNC collaboration: S. Aubin College of William and Mary, J. A. Behr TRIUMF, R. Collister U. Manitoba, E. Gomez UASLP, G. Gwinner U. Manitoba, M. R. Pearson TRIUMF, L. A. Orozco UMD, M. Tandecki TRIUMF, J. Zhang UMD Supported by NSF and DOE from the USA; TRIUMF, NRC and NSERC from Canada; and CONACYT from Mexico

  20. Mechanisms Undlerlying Quadriceps Weakness in Knee Osteoarthritis

    Science.gov (United States)

    PETTERSON, STEPHANIE C.; BARRANCE, PETER; BUCHANAN, THOMAS; BINDER-MACLEOD, STUART; SNYDER-MACKLER, LYNN

    2013-01-01

    Purpose To identify determinants of quadriceps weakness among persons with end-stage knee osteoarthritis (OA). Methods One-hundred twenty-three individuals (mean age 64.9 ± 8.5 yr) with Kellgren/Lawrence grade IV knee OA participated. Quadriceps strength (MVIC) and volitional muscle activation (CAR) were measured using a burst superimposition test. Muscle composition (lean muscle cross-sectional area (LMCSA) and fat CSA (FCSA)) were quantified using magnetic resonance imaging. Specific strength (MVIC/LMCSA) was computed. Interlimb differences were analyzed using paired-sample t-tests. Regression analysis was applied to identify determinants of MVIC. An alpha level of 0.05 was adopted. Results The OA limb was significantly weaker, had lower CAR, and had smaller LMCSA than the contralateral limb. CAR explained 17% of the variance in the contralateral limb's MVIC compared with 40% in the OA limb. LMCSA explained 41% of the variance in the contralateral limb's MVIC compared with 27% in the OA limb. Conclusion Both reduced CAR and LMCSA contribute to muscle weakness in persons with knee OA. Similar to healthy elders, the best predictor of strength in the contralateral, nondiseased limb was largely determined by LMCSA, whereas CAR was found to be the primary determinant of strength in the OA limb. Deficits in CAR may undermine the effectiveness of volitional strengthening programs in targeting quadriceps weakness in the OA population. PMID:18379202

  1. Mechanisms underlying quadriceps weakness in knee osteoarthritis.

    Science.gov (United States)

    Petterson, Stephanie C; Barrance, Peter; Buchanan, Thomas; Binder-Macleod, Stuart; Snyder-Mackler, Lynn

    2008-03-01

    To identify determinants of quadriceps weakness among persons with end-stage knee osteoarthritis (OA). One-hundred twenty-three individuals (mean age 64.9 +/- 8.5 yr) with Kellgren/Lawrence grade IV knee OA participated. Quadriceps strength (MVIC) and volitional muscle activation (CAR) were measured using a burst superimposition test. Muscle composition (lean muscle cross-sectional area (LMCSA) and fat CSA (FCSA)) were quantified using magnetic resonance imaging. Specific strength (MVIC/LMCSA) was computed. Interlimb differences were analyzed using paired-sample t-tests. Regression analysis was applied to identify determinants of MVIC. An alpha level of 0.05 was adopted. The OA limb was significantly weaker, had lower CAR, and had smaller LMCSA than the contralateral limb. CAR explained 17% of the variance in the contralateral limb's MVIC compared with 40% in the OA limb. LMCSA explained 41% of the variance in the contralateral limb's MVIC compared with 27% in the OA limb. Both reduced CAR and LMCSA contribute to muscle weakness in persons with knee OA. Similar to healthy elders, the best predictor of strength in the contralateral, nondiseased limb was largely determined by LMCSA, whereas CAR was found to be the primary determinant of strength in the OA limb. Deficits in CAR may undermine the effectiveness of volitional strengthening programs in targeting quadriceps weakness in the OA population.

  2. International magnetic pulse compression

    Science.gov (United States)

    Kirbie, H. C.; Newton, M. A.; Siemens, P. D.

    1991-04-01

    Although pulsed-power engineering traditionally has been practiced by a fairly small, close community in the areas of defense and energy research, it is becoming more common in high-power, high-energy commercial pursuits such as material processing and lasers. This paper is a synopsis of the Feb. 12-14, 1990 workshop on magnetic switching as it applies primarily to pulse compression (power transformation). During the course of the Workshop at Granlibakken, a great deal of information was amassed and a keen insight into both the problems and opportunities as to the use of this switching approach was developed. The segmented workshop format proved ideal for identifying key aspects affecting optimum performance in a variety of applications. Individual groups of experts addressed network and system modeling, magnetic materials, power conditioning, core cooling and dielectrics, and finally circuits and application. At the end, they came together to consolidate their input and formulate the workshop's conclusions, identifying roadblocks or suggesting research projects, particularly as they apply to magnetic switching's trump card - its high-average-power-handling capability (at least on a burst-mode basis). The workshop was especially productive both in the quality and quantity of information transfer in an environment conducive to a free and open exchange of ideas. We will not delve into the organization proper of this meeting, rather we wish to commend to the interested reader this volume, which provides the definitive and most up-to-date compilation on the subject of magnetic pulse compression from underlying principles to current state of the art as well as the prognosis for the future of magnetic pulse compression as a consensus of the workshop's organizers and participants.

  3. PULSE Pilot Certification Results

    Directory of Open Access Journals (Sweden)

    Pamela Pape-Lindstrom

    2015-08-01

    Full Text Available The pilot certification process is an ambitious, nationwide endeavor designed to motivate important changes in life sciences education that are in line with the recommendations of the 2011 Vision and Change Report: A Call to Action (American Association for the Advancement of Science [AAAS], 2011.  It is the goal of the certification process to acknowledge departments that have progressed towards full implementation of the tenets of Vision and Change and to motivate departments that have not begun to adopt the recommendations to consider doing so.  More than 70 life science departments applied to be part of the pilot certification process, funded by a National Science Foundation grant, and eight were selected based on initial evidence of transformed and innovative educational practices.  The programs chosen represent a wide variety of schools, including two-year colleges, liberal-arts institutions, regional comprehensive colleges, research universities and minority serving institutions.  Outcomes from this pilot were released June 1, 2015 (www.pulsecommunity.org, with all eight programs being recognized as having progressed along a continuum of change.  Five levels of achievement were defined as PULSE Pilot Progression Levels.  Of the eight departments in the pilot, one achieved “PULSE Progression Level III: Accomplished”.  Six departments achieved “PULSE Progression Level II: Developing” and one pilot department achieved “PULSE Progression Level I: Beginning”.  All of the schools have made significant movement towards the recommendations of Vision and Change relative to a traditional life sciences curriculum.  Overall, the response from the eight pilot schools has been positive. 

  4. Systematic review: role of acid, weakly acidic and weakly alkaline reflux in gastroesophageal reflux disease

    OpenAIRE

    Boeckxstaens, Guy E; Smout, Smout J

    2010-01-01

    Abstract Background The importance of weakly acidic and weakly alkaline reflux in gastroesophageal reflux disease (GERD) is gaining recognition. Aim To quantify the proportions of reflux episodes that are acidic (pH 7) in adult patients with GERD, and to evaluate their correlation with symptoms. Methods Studies were identified by systematic PubMed and Embase searches. Data are presented as sample-size weighted ...

  5. Modeling Pilot Pulse Control

    Science.gov (United States)

    Bachelder, Edward; Hess, Ronald; Godfroy-Cooper, Martine; Aponso, Bimal

    2017-01-01

    In this study, behavioral models are developed that closely reproduced pulsive control response of two pilots from the experimental pool using markedly different control techniques (styles) while conducting a tracking task. An intriguing find was that the pilots appeared to: 1) produce a continuous, internally-generated stick signal that they integrated in time; 2) integrate the actual stick position; and 3) compare the two integrations to issue and cease pulse commands. This suggests that the pilots utilized kinesthetic feedback in order to perceive and integrate stick position, supporting the hypothesis that pilots can access and employ the proprioceptive inner feedback loop proposed by Hess' pilot Structural Model. The Pulse Models used in conjunction with the pilot Structural Model closely recreated the pilot data both in the frequency and time domains during closed-loop simulation. This indicates that for the range of tasks and control styles encountered, the models captured the fundamental mechanisms governing pulsive and control processes. The pilot Pulse Models give important insight for the amount of remnant (stick output uncorrelated with the forcing function) that arises from nonlinear pilot technique, and for the remaining remnant arising from different sources unrelated to tracking control (i.e. neuromuscular tremor, reallocation of cognitive resources, etc.).

  6. Petawatt pulsed-power accelerator

    Science.gov (United States)

    Stygar, William A.; Cuneo, Michael E.; Headley, Daniel I.; Ives, Harry C.; Ives, legal representative; Berry Cottrell; Leeper, Ramon J.; Mazarakis, Michael G.; Olson, Craig L.; Porter, John L.; Wagoner; Tim C.

    2010-03-16

    A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

  7. Foundations of pulsed power technology

    CERN Document Server

    Lehr, Janet

    2018-01-01

    Pulsed power technologies could be an answer to many cutting-edge applications. The challenge is in how to develop this high-power/high-energy technology to fit current market demands of low-energy consuming applications. This book provides a comprehensive look at pulsed power technology and shows how it can be improved upon for the world of today and tomorrow. Foundations of Pulsed Power Technology focuses on the design and construction of the building blocks as well as their optimum assembly for synergetic high performance of the overall pulsed power system. Filled with numerous design examples throughout, the book offers chapter coverage on various subjects such as: Marx generators and Marx-like circuits; pulse transformers; pulse-forming lines; closing switches; opening switches; multi-gigawatt to multi-terawatt systems; energy storage in capacitor banks; electrical breakdown in gases; electrical breakdown in solids, liquids and vacuum; pulsed voltage and current measurements; electromagnetic interferen...

  8. Research on diversity receive technology for wireless optical communication using PPM in weak turbulence atmosphere channel

    Science.gov (United States)

    Liu, Yang; Zhang, Guo-an

    2014-09-01

    In order to mitigate atmospheric turbulence, the free space optical (FSO) system model with spatial diversity is analyzed based on intensity detection pulse position modulation (PPM) in the weak turbulence atmosphere. The slot error rate (SER) calculating formula of the system without diversity is derived under pulse position modulation firstly. Then as a benchmark, independent of identical distribution, the average slot error rates of the three linear combining technologies, which are the maximal ratio combining (MRC), equal gain combining (EGC) and selection combining (SelC), are compared. Simulation results show that the performance of system is the best improved by MRC, followed by EGC, and is poor by SelC, but SelC is simpler and more convenient. Spatial diversity is efficient to improve the performance and has strong ability on resistance to atmospheric channel decline. The above scheme is more suitable for optical wireless communication systems.

  9. Parametric excitation of optical phonons in weakly polar narrow band gap magnetized semiconductor plasmas

    Science.gov (United States)

    Sandeep; Dahiya, Sunita; Singh, Navneet

    2017-11-01

    An analytical treatment based on the hydrodynamic model of plasmas is developed to study parametric amplification and oscillation of optical phonon modes in weakly polar narrow direct-gap magnetized semiconductor plasmas. Second-order optical susceptibility arising due to nonlinear polarization and the basic operational characteristics of the parametric device, viz. threshold nature, power gain mechanisms and conversion efficiency, are obtained. The effects of doping, magnetic field and excitation intensity, on the above operational characteristics have been studied in detail. Numerical estimates are made for an n-InSb crystal at 5 K duly irradiated by a pulsed 10.6 μm CO2 laser. The analysis suggests the possibility of observing super-fluorescent parametric emission and oscillation in moderately doped n-InSb crystal under off-resonant nanosecond pulsed not-too-high power laser irradiation, the crystal being immersed in a large magnetic field.

  10. Systematic review: role of acid, weakly acidic and weakly alkaline reflux in gastro-oesophageal reflux disease

    NARCIS (Netherlands)

    Boeckxstaens, G. E.; Smout, A.

    2010-01-01

    The importance of weakly acidic and weakly alkaline reflux in gastro-oesophageal reflux disease (GERD) is gaining recognition. To quantify the proportions of reflux episodes that are acidic (pH <4), weakly acidic (pH 4-7) and weakly alkaline (pH >7) in adult patients with GERD, and to evaluate their

  11. Coherent control of indirect photofragmentation in the weak-field limit: Control of transient fragment distributions

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Henriksen, Niels Engholm

    2011-01-01

    We demonstrate theoretically that laser-induced coherent quantum interference control of asymptotic states of dissociating molecules is possible - even in the (one-photon) weak-field limit starting from a single vibrational eigenstate - when resonances are in play. This is illustrated for the Na......I molecule, where it is shown that the probability of observing atomic fragments as well as the distribution of their relative momenta can be changed by a phase modulated pulse with a fixed bandwidth. This type of control is restricted to finite times during the indirect fragmentation. (C) 2011 American...

  12. The magnetosphere under weak solar wind forcing

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2007-02-01

    Full Text Available The Earth's magnetosphere was very strongly disturbed during the passage of the strong shock and the following interacting ejecta on 21–25 October 2001. These disturbances included two intense storms (Dst*≈−250 and −180 nT, respectively. The cessation of this activity at the start of 24 October ushered in a peculiar state of the magnetosphere which lasted for about 28 h and which we discuss in this paper. The interplanetary field was dominated by the sunward component [B=(4.29±0.77, −0.30±0.71, 0.49±0.45 nT]. We analyze global indicators of geomagnetic disturbances, polar cap precipitation, ground magnetometer records, and ionospheric convection as obtained from SuperDARN radars. The state of the magnetosphere is characterized by the following features: (i generally weak and patchy (in time low-latitude dayside reconnection or reconnection poleward of the cusps; (ii absence of substorms; (iii a monotonic recovery from the previous storm activity (Dst corrected for magnetopause currents decreasing from ~−65 to ~−35 nT, giving an unforced decreased of ~1.1 nT/h; (iv the probable absence of viscous-type interaction originating from the Kelvin-Helmholtz (KH instability; (v a cross-polar cap potential of just 20–30 kV; (vi a persistent, polar cap region containing (vii very weak, and sometimes absent, electron precipitation and no systematic inter-hemisphere asymmetry. Whereas we therefore infer the presence of a moderate amount of open flux, the convection is generally weak and patchy, which we ascribe to the lack of solar wind driver. This magnetospheric state approaches that predicted by Cowley and Lockwood (1992 but has never yet been observed.

  13. The magnetosphere under weak solar wind forcing

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2007-02-01

    Full Text Available The Earth's magnetosphere was very strongly disturbed during the passage of the strong shock and the following interacting ejecta on 21–25 October 2001. These disturbances included two intense storms (Dst*≈−250 and −180 nT, respectively. The cessation of this activity at the start of 24 October ushered in a peculiar state of the magnetosphere which lasted for about 28 h and which we discuss in this paper. The interplanetary field was dominated by the sunward component [B=(4.29±0.77, −0.30±0.71, 0.49±0.45 nT]. We analyze global indicators of geomagnetic disturbances, polar cap precipitation, ground magnetometer records, and ionospheric convection as obtained from SuperDARN radars. The state of the magnetosphere is characterized by the following features: (i generally weak and patchy (in time low-latitude dayside reconnection or reconnection poleward of the cusps; (ii absence of substorms; (iii a monotonic recovery from the previous storm activity (Dst corrected for magnetopause currents decreasing from ~−65 to ~−35 nT, giving an unforced decreased of ~1.1 nT/h; (iv the probable absence of viscous-type interaction originating from the Kelvin-Helmholtz (KH instability; (v a cross-polar cap potential of just 20–30 kV; (vi a persistent, polar cap region containing (vii very weak, and sometimes absent, electron precipitation and no systematic inter-hemisphere asymmetry. Whereas we therefore infer the presence of a moderate amount of open flux, the convection is generally weak and patchy, which we ascribe to the lack of solar wind driver. This magnetospheric state approaches that predicted by Cowley and Lockwood (1992 but has never yet been observed.

  14. Spurious Shear in Weak Lensing with LSST

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.; Kahn, S.M.; Jernigan, J.G.; Peterson, J.R.; AlSayyad, Y.; Ahmad, Z.; Bankert, J.; Bard, D.; Connolly, A.; Gibson, R.R.; Gilmore, K.; Grace, E.; Hannel, M.; Hodge, M.A.; Jee, M.J.; Jones, L.; Krughoff, S.; Lorenz, S.; Marshall, P.J.; Marshall, S.; Meert, A.

    2012-09-19

    The complete 10-year survey from the Large Synoptic Survey Telescope (LSST) will image {approx} 20,000 square degrees of sky in six filter bands every few nights, bringing the final survey depth to r {approx} 27.5, with over 4 billion well measured galaxies. To take full advantage of this unprecedented statistical power, the systematic errors associated with weak lensing measurements need to be controlled to a level similar to the statistical errors. This work is the first attempt to quantitatively estimate the absolute level and statistical properties of the systematic errors on weak lensing shear measurements due to the most important physical effects in the LSST system via high fidelity ray-tracing simulations. We identify and isolate the different sources of algorithm-independent, additive systematic errors on shear measurements for LSST and predict their impact on the final cosmic shear measurements using conventional weak lensing analysis techniques. We find that the main source of the errors comes from an inability to adequately characterise the atmospheric point spread function (PSF) due to its high frequency spatial variation on angular scales smaller than {approx} 10{prime} in the single short exposures, which propagates into a spurious shear correlation function at the 10{sup -4}-10{sup -3} level on these scales. With the large multi-epoch dataset that will be acquired by LSST, the stochastic errors average out, bringing the final spurious shear correlation function to a level very close to the statistical errors. Our results imply that the cosmological constraints from LSST will not be severely limited by these algorithm-independent, additive systematic effects.

  15. Supersymmetric Higgs bosons in weak boson fusion.

    Science.gov (United States)

    Hollik, Wolfgang; Plehn, Tilman; Rauch, Michael; Rzehak, Heidi

    2009-03-06

    We compute the complete supersymmetric next-to-leading-order corrections to the production of a light Higgs boson in weak-boson fusion. The size of the electroweak corrections is of similar order as the next-to-leading-order corrections in the standard model. The supersymmetric QCD corrections turn out to be significantly smaller than expected and than their electroweak counterparts. These corrections are an important ingredient to a precision analysis of the (supersymmetric) Higgs sector at the LHC, either as a known correction factor or as a contribution to the theory error.

  16. Are the Weak Measurements Really Measurements?

    Directory of Open Access Journals (Sweden)

    Dmitri Sokolovski

    2013-05-01

    Full Text Available Weak measurements can be seen as an attempt at answering the Which way? question without destroying interference between the pathways involved. Unusual mean values obtained in such measurements represent the response of a quantum system to this forbidden question, in which the true composition of virtual pathways is hidden from the observer. Such values indicate a failure of a measurement where the uncertainty principle says it must fail, rather than provide an additional insight into physical reality. Quanta 2013; 2: 50–57.

  17. Legitimacy Building under Weak Institutional Settings

    DEFF Research Database (Denmark)

    Wejs, Anja; Harvold, Kjell; Larsen, Sanne Vammen

    2014-01-01

    Local strategies for adaptation to climate change in Denmark and Norway are discussed. In both countries, the national impetus for local adaptation is weak; it is largely left to local actors to take the initiative. The dynamics of the different approaches to climate-change adaptation at the local...... level are illuminated. Using decision-making and learning theory, we present an analytical framework to examine four cases, two in Norway and two in Denmark, which represent two different responses, i.e. anticipatory actions and obligatory actions. We find that, by bringing in knowledge and resources...

  18. Superconductor in a weak static gravitational field

    Energy Technology Data Exchange (ETDEWEB)

    Ummarino, Giovanni Alberto [Dipartimento DISAT, Politecnico di Torino, Turin (Italy); National Research Nuclear University MEPhI-Moscow Engineering Physics Institute, Moscow (Russian Federation); Gallerati, Antonio [Dipartimento DISAT, Politecnico di Torino, Turin (Italy)

    2017-08-15

    We provide the detailed calculation of a general form for Maxwell and London equations that takes into account gravitational corrections in linear approximation. We determine the possible alteration of a static gravitational field in a superconductor making use of the time-dependent Ginzburg-Landau equations, providing also an analytic solution in the weak field condition. Finally, we compare the behavior of a high-T{sub c} superconductor with a classical low-T{sub c} superconductor, analyzing the values of the parameters that can enhance the reduction of the gravitational field. (orig.)

  19. Infrared spectroscopy of weakly bound molecular ions

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, Lisa I-Ching

    1988-11-01

    The infrared spectra of a series of hydrated hydronium cluster ions and of protonated ethane ion are presented. A tandem mass spectrometer is ideally suited to obtaining the spectra of such weakly bound molecular ions. Traditional absorption spectroscopy is not feasible in these situations, so the techniques described in this thesis make use of some consequence of photon absorption with higher sensitivity than simply attenuation of laser power. That consequence is dissociation. By first mass selecting the parent ion under study and then mass selecting the fragment ion formed from dissociation, the near unit detection efficiency of ion counting methods has been used to full advantage.

  20. Weak η production off the nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Alam, M. Rafi; Athar, M. Sajjad [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India); Alvarez-Ruso, L.; Vacas, M. J. Vicente [Departamento de Física Teórica and Instituto de Física Corpuscular, Centro Mixto Universidad de Valencia-CSIC, E-46071 Valencia (Spain)

    2015-05-15

    The weak η-meson production off the nucleon induced by (anti)neutrinos is studied at low and intermediate energies, the range of interest for several ongoing and future neutrino experiments. We consider Born diagrams and the excitation of N{sup *} (1535)S{sub 11} and N{sup *} (1650)S{sub 11} resonances. The vector part of the N-S{sub 11} transition form factors has been obtained from the MAID helicity amplitudes while the poorly known axial part is constrained with the help of the partial conservation of the axial current (PCAC) and assuming the pion-pole dominance of the pseudoscalar form factor.

  1. Coiled transmission line pulse generators

    Science.gov (United States)

    McDonald, Kenneth Fox

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  2. A pulsated weak-resonant-cavity laser diode with transient wavelength scanning and tracking for injection-locked RZ transmission.

    Science.gov (United States)

    Lin, Gong-Ru; Chi, Yu-Chieh; Liao, Yu-Sheng; Kuo, Hao-Chung; Liao, Zhi-Wang; Wang, Hai-Lin; Lin, Gong-Cheng

    2012-06-18

    By spectrally slicing a single longitudinal-mode from a master weak-resonant-cavity Fabry-Perot laser diode with transient wavelength scanning and tracking functions, the broadened self-injection-locking of a slave weak-resonant-cavity Fabry-Perot laser diode is demonstrated to achieve bi-directional transmission in a 200-GHz array-waveguide-grating channelized dense-wavelength-division-multiplexing passive optical network system. Both the down- and up-stream slave weak-resonant-cavity Fabry-Perot laser diodes are non-return-to-zero modulated below threshold and coherently injection-locked to deliver the pulsed carrier for 25-km bi-directional 2.5 Gbits/s return-to-zero transmission. The master weak-resonant-cavity Fabry-Perot laser diode is gain-switched at near threshold condition and delivers an optical coherent pulse-train with its mode linewidth broadened from 0.2 to 0.8 nm by transient wavelength scanning, which facilitates the broadband injection-locking of the slave weak-resonant-cavity Fabry-Perot laser diodes with a threshold current reducing by 10 mA. Such a transient wavelength scanning induced spectral broadening greatly releases the limitation on wavelength injection-locking range required for the slave weak-resonant-cavity Fabry-Perot laser diode. The theoretical modeling and numerical simulation on the wavelength scanning and tracking effects of the master and slave weak-resonant-cavity Fabry-Perot laser diodes are performed. The receiving power sensitivity for back-to-back transmission at bit-error-rate transmission is less than 2 dB for all 16 channels.

  3. Coherent hard x rays from attosecond pulse train-assisted harmonic generation.

    Science.gov (United States)

    Klaiber, Michael; Hatsagortsyan, Karen Z; Müller, Carsten; Keitel, Christoph H

    2008-02-15

    High-order harmonic generation from atomic systems is considered in the crossed fields of a relativistically strong infrared laser and a weak attosecond pulse train of soft x rays. Due to one-photon ionization by the x-ray pulse, the ionized electron obtains a starting momentum that compensates the relativistic drift, which is induced by the laser magnetic field, and allows the electron to efficiently emit harmonic radiation upon recombination with the atomic core in the relativistic regime. This way, short pulses of coherent hard x rays of up to 40 keV energy can be generated.

  4. Microwave and Pulsed Power

    Energy Technology Data Exchange (ETDEWEB)

    Freytag, E.K.

    1993-03-01

    The goals of the Microwave and Pulsed Power thrust area are to identify realizable research and development efforts and to conduct high-quality research in those pulse power and microwave technologies that support existing and emerging programmatic requirements at Lawrence Livermore National Laboratory (LLNL). Our main objective is to work on nationally important problems while enhancing our basic understanding of enabling technologies such as component design and testing, compact systems packaging, exploratory physics experiments, and advanced systems integration and performance. During FY-92, we concentrated our research efforts on the six project areas described in this report. (1) We are investigating the superior electronic and thermal properties of diamond that may make it an ideal material for a high-power, solid-state switch. (2) We are studying the feasibility of using advanced Ground Penetrating Imaging Radar technology for reliable non-destructive evaluation of bridges and other high-value concrete structures. These studies include conceptual designs, modeling, experimental verifications, and image reconstruction of simulated radar data. (3) We are exploring the efficiency of pulsed plasma processing techniques used for the removal of NO{sub x} from various effluent sources. (4) We have finished the investigation of the properties of a magnetically delayed low-pressure gas switch, which was designed here at LLNL. (5) We are applying statistical electromagnetic theory techniques to help assess microwave effects on electronic subsystems, by using a mode stirred chamber as our measurement tool. (6) We are investigating the generation of perfluoroisobutylene (PFIB) in proposed CFC replacement fluids when they are subjected to high electrical stresses and breakdown environments.

  5. Intense pulsed light therapy.

    Science.gov (United States)

    Soltes, Barbara

    2010-12-01

    Intense Pulsed Light (IPL) is an FDA-approved photo therapy for the treatment of a variety of conditions such as acne and hirsutism. It utilizes the principle of selective photothermolysis. Photothermolysis allows a specific wavelength to be delivered to a chromophore of a designated tissue while leaving the surrounding tissue unaffected. The results of IPL are similar to that of laser treatments but it offers the advantage of a relative low cost. It is a safe and rapid treatment with minimal discomfort to the patient. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. A Pulsed Sphere Tutorial

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, Dermott E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-01-30

    Here I attempt to explain what physically happens when we pulse an object with neutrons, specifically what we expect the time dependent behavior of the neutron population to look like. Emphasis is on the time dependent emission of both prompt and delayed neutrons. I also describe how the TART Monte Carlo transport code models this situation; see the appendix for a complete description of the model used by TART. I will also show that, as we expect, MCNP and MERCURY, produce similar results using the same delayed neutron model (again, see the appendix).

  7. Africa's Pulse, October 2014

    OpenAIRE

    Punam, Chuhan-Pole; Ferreira, Francisco H. G.

    2014-01-01

    Africa’s Pulse is a biannual publication containing an analysis of the near-term macro-economic outlook for the region. It also includes a section focusing on a topic that represents a particular development challenges for the continent. It is produced by the Office of the Chief Economist for the Africa Region.This issue is an analysis of issues shaping Africa's economic future. Growth remains stable in Sub-Saharan Africa. Some countries are seeing a slowdown, but the region's economic pros...

  8. Optimal Weak-Lensing Skewness Measurements

    Science.gov (United States)

    Zhang, Tong-Jie; Pen, Ue-Li; Zhang, Pengjie; Dubinski, John

    2003-12-01

    Weak-lensing measurements are starting to provide statistical maps of the distribution of matter in the universe that are increasingly precise and complementary to cosmic microwave background maps. The most common measurement is the correlation in alignments of background galaxies, which can be used to infer the variance of the projected surface density of matter. This measurement of the fluctuations is insensitive to the total mass content and is analogous to using waves on the ocean to measure its depths. However, when the depth is shallow, as happens near a beach, waves become skewed. Similarly, a measurement of skewness in the projected matter distribution directly measures the total matter content of the universe. While skewness has already been convincingly detected, its constraint on cosmology is still weak. We address optimal analyses for the Canada-France-Hawaii Telescope Legacy Survey in the presence of noise. We show that a compensated Gaussian filter with a width of 2.5‧ optimizes the cosmological constraint, yielding ΔΩm/Ωm~10%. This is significantly better than other filters that have been considered in the literature. This can be further improved with tomography and other sophisticated analyses.

  9. Conformational transitions of a weak polyampholyte

    KAUST Repository

    Nair, Arun Kumar Narayanan

    2014-10-07

    Using grand canonical Monte Carlo simulations of a flexible polyelectrolyte where the charges are in contact with a reservoir of constant chemical potential given by the solution pH, we study the behavior of weak polyelectrolytes in poor and good solvent conditions for polymer backbone. We address the titration behavior and conformational properties of a flexible diblock polyampholyte chain formed of two oppositely charged weak polyelectrolyte blocks, each containing equal number of identical monomers. The change of solution pH induces charge asymmetry in a diblock polyampholyte. For diblock polyampholyte chains in poor solvents, we demonstrate that a discontinuous transition between extended (tadpole) and collapsed (globular) conformational states is attainable by varying the solution pH. The double-minima structure in the probability distribution of the free energy provides direct evidence for the first-order like nature of this transition. At the isoelectric point electrostatically driven coil-globule transition of diblock polyampholytes in good solvents is found to consist of different regimes identified with increasing electrostatic interaction strength. At pH values above or below the isoelectric point diblock chains are found to have polyelectrolyte-like behavior due to repulsion between uncompensated charges along the chain.

  10. Synchronizability of nonidentical weakly dissipative systems

    Science.gov (United States)

    Sendiña-Nadal, Irene; Letellier, Christophe

    2017-10-01

    Synchronization is a very generic process commonly observed in a large variety of dynamical systems which, however, has been rarely addressed in systems with low dissipation. Using the Rössler, the Lorenz 84, and the Sprott A systems as paradigmatic examples of strongly, weakly, and non-dissipative chaotic systems, respectively, we show that a parameter or frequency mismatch between two coupled such systems does not affect the synchronizability and the underlying structure of the joint attractor in the same way. By computing the Shannon entropy associated with the corresponding recurrence plots, we were able to characterize how two coupled nonidentical chaotic oscillators organize their dynamics in different dissipation regimes. While for strongly dissipative systems, the resulting dynamics exhibits a Shannon entropy value compatible with the one having an average parameter mismatch, for weak dissipation synchronization dynamics corresponds to a more complex behavior with higher values of the Shannon entropy. In comparison, conservative dynamics leads to a less rich picture, providing either similar chaotic dynamics or oversimplified periodic ones.

  11. Do weak global stresses synchronize earthquakes?

    Science.gov (United States)

    Bendick, R.; Bilham, R.

    2017-08-01

    Insofar as slip in an earthquake is related to the strain accumulated near a fault since a previous earthquake, and this process repeats many times, the earthquake cycle approximates an autonomous oscillator. Its asymmetric slow accumulation of strain and rapid release is quite unlike the harmonic motion of a pendulum and need not be time predictable, but still resembles a class of repeating systems known as integrate-and-fire oscillators, whose behavior has been shown to demonstrate a remarkable ability to synchronize to either external or self-organized forcing. Given sufficient time and even very weak physical coupling, the phases of sets of such oscillators, with similar though not necessarily identical period, approach each other. Topological and time series analyses presented here demonstrate that earthquakes worldwide show evidence of such synchronization. Though numerous studies demonstrate that the composite temporal distribution of major earthquakes in the instrumental record is indistinguishable from random, the additional consideration of event renewal interval serves to identify earthquake groupings suggestive of synchronization that are absent in synthetic catalogs. We envisage the weak forces responsible for clustering originate from lithospheric strain induced by seismicity itself, by finite strains over teleseismic distances, or by other sources of lithospheric loading such as Earth's variable rotation. For example, quasi-periodic maxima in rotational deceleration are accompanied by increased global seismicity at multidecadal intervals.

  12. Weak gravity conjecture and effective field theory

    Science.gov (United States)

    Saraswat, Prashant

    2017-01-01

    The weak gravity conjecture (WGC) is a proposed constraint on theories with gauge fields and gravity, requiring the existence of light charged particles and/or imposing an upper bound on the field theory cutoff Λ . If taken as a consistency requirement for effective field theories (EFTs), it rules out possibilities for model building including some models of inflation. I demonstrate simple models which satisfy all forms of the WGC, but which through Higgsing of the original gauge fields produce low-energy EFTs with gauge forces that badly violate the WGC. These models illustrate specific loopholes in arguments that motivate the WGC from a bottom-up perspective; for example the arguments based on magnetic monopoles are evaded when the magnetic confinement that occurs in a Higgs phase is accounted for. This indicates that the WGC should not be taken as a veto on EFTs, even if it turns out to be a robust property of UV quantum gravity theories. However, if the latter is true, then parametric violation of the WGC at low energy comes at the cost of nonminimal field content in the UV. I propose that only a very weak constraint is applicable to EFTs, Λ ≲(log 1/g )-1 /2Mpl , where g is the gauge coupling, motivated by entropy bounds. Remarkably, EFTs produced by Higgsing a theory that satisfies the WGC can saturate but not violate this bound.

  13. Probing hysteretic elasticity in weakly nonlinear materials

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Paul A [Los Alamos National Laboratory; Haupert, Sylvain [UPMC UNIV PARIS; Renaud, Guillaume [UPMC UNIV PARIS; Riviere, Jacques [UPMC UNIV PARIS; Talmant, Maryline [UPMC UNIV PARIS; Laugier, Pascal [UPMC UNIV PARIS

    2010-12-07

    Our work is aimed at assessing the elastic and dissipative hysteretic nonlinear parameters' repeatability (precision) using several classes of materials with weak, intermediate and high nonlinear properties. In this contribution, we describe an optimized Nonlinear Resonant Ultrasound Spectroscopy (NRUS) measuring and data processing protocol applied to small samples. The protocol is used to eliminate the effects of environmental condition changes that take place during an experiment, and that may mask the intrinsic elastic nonlinearity. As an example, in our experiments, we identified external temperature fluctuation as a primary source of material resonance frequency and elastic modulus variation. A variation of 0.1 C produced a frequency variation of 0.01 %, which is similar to the expected nonlinear frequency shift for weakly nonlinear materials. In order to eliminate environmental effects, the variation in f{sub 0} (the elastically linear resonance frequency proportional to modulus) is fit with the appropriate function, and that function is used to correct the NRUS calculation of nonlinear parameters. With our correction procedure, we measured relative resonant frequency shifts of 10{sup -5} , which are below 10{sup -4}, often considered the limit to NRUS sensitivity under common experimental conditions. Our results show that the procedure is an alternative to the stringent control of temperature often applied. Applying the approach, we report nonlinear parameters for several materials, some with very small nonclassical nonlinearity. The approach has broad application to NRUS and other Nonlinear Elastic Wave Spectroscopy approaches.

  14. A Bibliographical Research of the Correlation Among Sasang Constitutional Disease and the Pulse Diagnosis

    Directory of Open Access Journals (Sweden)

    Kim Dong-jun

    2003-06-01

    Full Text Available The purpose of this research was to investigate the correlation Among Sasang Constitutional Disease and Examination of the pulse. I have gone over literatures of mainly 「Dongyi Soose Bowon」and the others Oriental Medical book was studied about the Pulse Diagnosis. And then I came to get some conclusion as follows. 1. Soeumin(소음인 the initial-stage symptoms of wulkwang disease(울광증; when the Superficial Pulse and the Superficial+Moderate Pulse is made a diagnosis, Ceongunggyegitang(천궁계지탕 and Gunggyuhyangsosan(궁귀향소산 can be used. 2. Soeumin(소음인 the initial-stage blood disease symptoms of wulkwang disease(울광증; when the Minute+deep Pulse is made a diagnosis, Palmulgunjatang(팔물군자탕 and Guakhyanggeonggisan(곽향정기산 can be used. 3. Soeumin(소음인 the initial-stage symptoms of mangyang disease(망양증; when the Yang region Superficial Pulse and the Yin region Weak Pulse is made a diagnosis, Hwanggigyegitang(황기계지탕, Bojungikgitang(보중익기탕 and Sengyangikgitang(승양익기탕 can be used. 4. Soeumin(소음인 the symptoms of taeum disease(태음증; when the Minute Pulse and Deep+Thin Pulse is made a diagnosis, Sasang Prescription can be used. 5. Soeumin(소음인 the symptoms of soeum disease(소음증; when the Minute+Thin Pulse, Deep Pulse and Thin+Deep+Rapid Pulse is made a diagnosis, Sasang Prescription can be used. 6. Soyangin(소양인 Wind of soyang disease(소양상풍증; when the Superficial+Tight Pulse is made a diagnosis, Hungbangpaedogsan(형방패독산 can be used. And when the Deep+Full with strong power Pulse is made a diagnosis, Hyungbangdojeoksan(형방도적산 can be used. 7. Soyangin(소양인 the symptoms of mangyeum disease(망음증; when the Superficial+Large+Rapid Pulse and Flood+Large Pulse is made a diagnosis, Hungbangsabaeksan(형방사백산 can be used. And when the Wiry+Thin Pulse is made a diagnosis, Hungbanggiwhangtang(형방지황탕 can

  15. Bipolar pulse forming line

    Science.gov (United States)

    Rhodes, Mark A.

    2008-10-21

    A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  16. Heat driven pulse pump

    Science.gov (United States)

    Benner, Steve M (Inventor); Martins, Mario S. (Inventor)

    2000-01-01

    A heat driven pulse pump includes a chamber having an inlet port, an outlet port, two check valves, a wick, and a heater. The chamber may include a plurality of grooves inside wall of the chamber. When heated within the chamber, a liquid to be pumped vaporizes and creates pressure head that expels the liquid through the outlet port. As liquid separating means, the wick, disposed within the chamber, is to allow, when saturated with the liquid, the passage of only liquid being forced by the pressure head in the chamber, preventing the vapor from exiting from the chamber through the outlet port. A plurality of grooves along the inside surface wall of the chamber can sustain the liquid, which is amount enough to produce vapor for the pressure head in the chamber. With only two simple moving parts, two check valves, the heat driven pulse pump can effectively function over the long lifetimes without maintenance or replacement. For continuous flow of the liquid to be pumped a plurality of pumps may be connected in parallel.

  17. Assembly delay line pulse generators

    CERN Multimedia

    CERN PhotoLab

    1971-01-01

    Assembly of six of the ten delay line pulse generators that will power the ten kicker magnet modules. One modulator part contains two pulse generators. Capacitors, inductances, and voltage dividers are in the oil tank on the left. Triggered high-pressure spark gap switches are on the platforms on the right. High voltage pulse cables to the kicker magnet emerge under the spark gaps. In the centre background are the assembled master gaps.

  18. Pulse Dispersion in Phased Arrays

    Directory of Open Access Journals (Sweden)

    Randy L. Haupt

    2017-01-01

    Full Text Available Phased array antennas cause pulse dispersion when receiving or transmitting wideband signals, because phase shifting the signals does not align the pulse envelopes from the elements. This paper presents two forms of pulse dispersion that occur in a phased array antenna. The first results from the separation distance between the transmit and receive antennas and impacts the definition of far field in the time domain. The second is a function of beam scanning and array size. Time delay units placed at the element and/or subarrays limit the pulse dispersion.

  19. Analysis of Pulse Modulated Control Systems (Ⅲ) Stability of Systems with Pulse Frequency Modulation and Systems with Combined Pulse Frequency and Pulse Width Modulation

    OpenAIRE

    OI,Shigemitsu

    1993-01-01

    Sufficient conditions for finite pulse stability of interconnected systems with combined pulse frequency and pulse width modulation are developed in this paper using a direct method. The stability criteria established provide upper bounds on the number of pulses emitted by each modulator. The results are also applicable to those systems which contain a finite number of pulse frequency modulators and a finite number of combined pulse frequency and pulse width modulators

  20. Weak and strong typicality in quantum systems.

    Science.gov (United States)

    Santos, Lea F; Polkovnikov, Anatoli; Rigol, Marcos

    2012-07-01

    We study the properties of mixed states obtained from eigenstates of many-body lattice Hamiltonians after tracing out part of the lattice. Two scenarios emerge for generic systems: (i) The diagonal entropy becomes equivalent to the thermodynamic entropy when a few sites are traced out (weak typicality); and (ii) the von Neumann (entanglement) entropy becomes equivalent to the thermodynamic entropy when a large fraction of the lattice is traced out (strong typicality). Remarkably, the results for few-body observables obtained with the reduced, diagonal, and canonical density matrices are very similar to each other, no matter which fraction of the lattice is traced out. Hence, for all physical quantities studied here, the results in the diagonal ensemble match the thermal predictions.

  1. Search for a new weakly interacting particle

    Science.gov (United States)

    Decamp, D.; Deschizeaux, B.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Alemany, R.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Gaitan, V.; Garrido, Ll.; Mato, P.; Ll. M., Mir; Pacheco, A.; Catanesi, M. G.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Maggi, M.; Natali, S.; Nuzzo, S.; Quattromini, M.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Gao, Y.; Hu, H.; Huang, D.; Huang, X.; Lin, J.; Lou, J.; Qiao, C.; Ruan, T.; Wang, T.; Xie, Y.; Xu, D.; Xu, R.; Zhang, J.; Zhao, W.; Atwood, W. B.; Bird, F.; Blucher, E.; Bonvicini, G.; Bossi, F.; Brown, D.; Burnett, T. H.; Drevermann, H.; Dydak, F.; Forty, R. W.; Grab, C.; Hagelberg, R.; Haywood, S.; Hilgart, J.; Jost, B.; Kasemann, M.; Knobloch, J.; Lacourt, A.; Lançon, E.; Lehraus, I.; Lohse, T.; Marchioro, A.; Martinez, M.; Menary, S.; Minten, A.; Miotto, A.; Miguel, R.; Moser, H.-G.; Nash, J.; Palazzi, P.; Ranjard, F.; Redlinger, G.; Roth, A.; Rothberg, J.; Rotscheidt, H.; St. Denis, R.; Schlatter, D.; Takashima, M.; Talby, M.; Tejessy, W.; Wachsmuth, H.; Wasserbaech, S.; Wheeler, S.; Wiedenmann, W.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Bardadin-Otwinowska, M.; Falvard, A.; El Fellous, R.; Gay, P.; Harvey, J.; Henrard, P.; Jousset, J.; Michel, B.; Montret, J.-C.; Pallin, D.; Perret, P.; Proriol, J.; Prulhière, F.; Stimpfl, G.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Møllerud, R.; Nielsen, E. R.; Nilsson, B. S.; Efthymiopoulos, I.; Simopoulou, E.; Vayaki, A.; Badier, J.; Blondel, A.; Bonneaud, G.; Bourotte, J.; Braems, F.; Brient, J. C.; Fouque, G.; Gamess, A.; Guirlet, R.; Orteu, S.; Rosowsky, A.; Rougé, A.; Rumpf, M.; Tanaka, R.; Videau, H.; Candlin, D. J.; Veitch, E.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Ikeda, M.; Lannutti, J.; Levinthal, D.; Mermikides, M.; Sawyer, L.; Antonelli, A.; Baldini, R.; Bencivenni, G.; Bologna, G.; Campana, P.; Capon, G.; Chiarella, V.; D'Ettorre-Piazzoli, B.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Nicoletti, G.; Passalacqua, L.; Pepe-Altarelli, M.; Picchi, P.; Zografou, P.; Altoon, B.; Boyle, O.; Halley, A. W.; Ten Have, I.; Hearns, J. L.; Lynch, J. G.; Morton, W. T.; Raine, C.; Scarr, J. M.; Smith, K.; Thompson, A. S.; Turnbull, R. M.; Brandl, B.; Braun, O.; Geiges, R.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Maumary, Y.; Putzer, A.; Rensch, B.; Stahl, A.; Tittel, K.; Wunsch, M.; Belk, A. T.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Cattaneo, M.; Dornan, P. J.; Dugeay, S.; Greene, A. M.; Hassard, J. F.; Lieske, N. M.; Patton, S. J.; Payne, D. G.; Phillips, M. J.; Sedgbeer, J. K.; Taylor, G.; Tomalin, I. R.; Wright, A. G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Keemer, N. R.; Nuttall, M.; Patel, A.; Rowlingson, B. S.; Sloan, T.; Snow, S. W.; Whelan, E. P.; Barczewski, T.; Bauerdick, L. A. T.; Kleinknecht, K.; Renk, B.; Roehn, S.; Sander, H.-G.; Schmelling, M.; Schmidt, H.; Steeg, F.; Albanese, J.-P.; Aubert, J.-J.; Benchouk, C.; Bernard, V.; Bonissent, A.; Courvoisier, D.; Etienne, F.; Papalexiou, S.; Payre, P.; Pietrzyk, B.; Qian, Z.; Becker, H.; Blum, W.; Cattaneo, P.; Cowan, G.; Dehning, B.; Dietl, H.; Fernandez-Bosman, M.; Hansl-Kozanecka, T.; Jahn, A.; Kozanecki, W.; Lange, E.; Lauber, J.; Lütjens, G.; Lutz, G.; Männer, W.; Pan, Y.; Richter, R.; Schröder, J.; Schwarz, A. S.; Settles, R.; Stierlin, U.; Thomas, J.; Wolf, G.; Bertin, V.; Boucrot, J.; Callot, O.; Chen, X.; Cordier, A.; Davier, M.; Ganis, G.; Grivaz, J.-F.; Heusse, Ph.; Janot, P.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Veillet, J.-J.; Videau, I.; Zhang, Z.; Zomer, F.; Amendolia, S. R.; Bagliesi, G.; Batignani, G.; Bosisio, L.; Bottigli, U.; Bradaschia, C.; Carpinelli, M.; Ciocci, M. A.; dell'Orso, R.; Ferrante, I.; Fidecaro, F.; Foà, L.; Focardi, E.; Forti, F.; Giassi, A.; Giorgi, M. A.; Ligabue, F.; Lusiani, A.; Mannelli, E. B.; Marrocchesi, P. S.; Messineo, A.; Moneta, L.; Palla, F.; Sanguinetti, G.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Vannini, C.; Venturi, A.; Verdini, P. G.; Walsh, J.; Carter, J. M.; Green, M. G.; March, P. V.; Medcalf, T.; Quazi, I. S.; Saich, M. R.; Strong, J. A.; Thomas, R. M.; West, L. R.; Wildish, T.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Edwards, M.; Fisher, S. M.; Jones, T. J.; Norton, P. R.; Salmon, D. P.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Klopfenstein, C.; Locci, E.; Loucatos, S.; Monnier, E.; Perez, P.; Perlas, J. A.; Perrier, F.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Vallage, B.; Ashman, J. G.; Booth, C. N.; Buttar, C.; Carney, R.; Cartwright, S.; Combley, F.; Dinsdale, M.; Dogru, M.; Hatfield, F.; Martin, J.; Parker, D.; Reeves, P.; Thompson, L. F.; Brandt, S.; Burkhardt, H.; Grupen, C.; Meinhard, H.; Mirabito, L.; Neugebauer, E.; Schäfer, U.; Seywerd, H.; Apollinari, G.; Giannini, G.; Gobbo, B.; Liello, F.; Ragusa, F.; Rolandi, L.; Stiegler, U.; Bellantoni, L.; Boudreau, J. F.; Cinabro, D.; Conway, J. S.; Cowen, D. F.; Deweerd, A. J.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; Grahl, J.; Harton, J. L.; Jacobsen, J. E.; Jared, R. C.; Johnson, R. P.; Leclaire, B. W.; Pan, Y. B.; Pater, J. R.; Saadi, Y.; Sharma, V.; Walsh, A. M.; Wear, J. A.; Weber, F. V.; Whitney, M. H.; Sau, Lan, Wu; Zhou, Z. L.; Zobernig, G.

    1991-06-01

    A search for events of the type e+e--->l+l-X0, where X0 can be any weakly interacting particle which couples to the Z, has been performed with the ALEPH detector at LEP, by searching for acollinear lepton pairs. Such particles can be excluded up to a mass of 7.0 GeV/c2 for a value of the ratio of branching fractions, Br(Z-->X0l+l-)/Br(Z-->l+l-), greater than 2.5 × 10-3 if the X0 has third component of isospin, I3 greater than 1/2 and decays to a pair of virtual gauge bosons. When this analysis is combined with the previous results of the Higgs particle searches from ALEPH, this limit can be extended to an X0 mass of 60 GeV/c2.

  2. Simulating Error in Cluster Weak Lensing Tomography

    Science.gov (United States)

    Murphy, Kellen J.

    2012-01-01

    We present the results of an N-body simulation of the various sources of systematic error in constraining the dark energy equation of state via cluster weak lensing tomography. The use of tomographic techniques to constrain the dark energy equation of state parameter is a pivotal component of future large survey missions, however, the application of tomography to cosmic shear necessitates the exclusion of regions around galaxy clusters from analysis. We therefore test the applicability tomography to cluster-induced shear as a secondary, complementary sample through which estimates of the dark energy e.o.s. parameter can be made. Furthermore, we demonstrate the application of this technique to a test sample of 10 massive galaxy clusters imaged by the Hubble Space Telescope.

  3. Casimir apparatuses in a weak gravitational field

    DEFF Research Database (Denmark)

    Bimonte, Giuseppe; Calloni, Enrico; Esposito, Giampiero

    2009-01-01

    We review and assess a part of the recent work on Casimir apparatuses in the weak gravitational field of the Earth. For a free, real massless scalar field subject to Dirichlet or Neumann boundary conditions on the parallel plates, the resulting regularized and renormalized energy-momentum tensor...... is covariantly conserved, while the trace anomaly vanishes if the massless field is conformally coupled to gravity. Conformal coupling also ensures a finite Casimir energy and finite values of the pressure upon parallel plates. These results have been extended to an electromagnetic field subject to perfect...... conductor (hence idealized) boundary conditions on parallel plates, by various authors. The regularized and renormalized energy-momentum tensor has beene valuated up to second order in the gravity acceleration. In both the scalar and the electromagnetic case, studied to first order in the gravity...

  4. A Soberania Fraca / The Weak Sovereignty

    Directory of Open Access Journals (Sweden)

    Maíra Matthes

    2012-12-01

    Full Text Available Resumo Em Vadios: Dois Ensaios sobre a Razão, Derrida propõe que se entenda o conceito de soberania a partir de duas noções principais: incondicionalidade e indivisibilidade. O objetivo desse artigo é mostrar que o autor aborda esses dois pontos com o intuito de criar uma compreensão da soberania como uma força fraca e divisível no tempo. Palavras Chaves: Soberania, Jacques Derrida, Filosofia Francesa, Voyous, Política. Abstract In Rogues: Two Essays on Reason, Derrida argues that sovereignty is comprised of two main features: the unconditional and the indivisible. The aim of this article is to show that the author approaches these aspects in order to make a point about the concept of sovereignty. This point is precisely to think sovereignty as a weak force and as something divisible in time. Key Words: Sovereignty, Jacques Derrida, French Philosophy, Rogues, Politics.

  5. Sex hormones and skeletal muscle weakness

    DEFF Research Database (Denmark)

    Sipilä, Sarianna; Narici, Marco; Kjaer, Michael

    2013-01-01

    Human ageing is accompanied with deterioration in endocrine functions the most notable and well characterized of which being the decrease in the production of sex hormones. Current research literature suggests that low sex hormone concentration may be among the key mechanism for sarcopenia...... and muscle weakness. Within the European large scale MYOAGE project, the role of sex hormones, estrogens and testosterone, in causing the aging-related loss of muscle mass and function was further investigated. Hormone replacement therapy (HRT) in women is shown to diminish age-associated muscle loss, loss...... properties. HRT influences gene expression in e.g. cytoskeletal and cell-matrix proteins, has a stimulating effect upon IGF-I, and a role in IL-6 and adipokine regulation. Despite low circulating steroid-hormone level, postmenopausal women have a high local concentration of steroidogenic enzymes in skeletal...

  6. Magnified Weak Lensing Cross Correlation Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ulmer, Melville P., Clowe, Douglas I.

    2010-11-30

    This project carried out a weak lensing tomography (WLT) measurement around rich clusters of galaxies. This project used ground based photometric redshift data combined with HST archived cluster images that provide the WLT and cluster mass modeling. The technique has already produced interesting results (Guennou et al, 2010,Astronomy & Astrophysics Vol 523, page 21, and Clowe et al, 2011 to be submitted). Guennou et al have validated that the necessary accuracy can be achieved with photometric redshifts for our purposes. Clowe et al titled "The DAFT/FADA survey. II. Tomographic weak lensing signal from 10 high redshift clusters," have shown that for the **first time** via this purely geometrical technique, which does not assume a standard rod or candle, that a cosmological constant is **required** for flat cosmologies. The intent of this project is not to produce the best constraint on the value of the dark energy equation of state, w. Rather, this project is to carry out a sustained effort of weak lensing tomography that will naturally feed into the near term Dark Energy Survey (DES) and to provide invaluable mass calibration for that project. These results will greatly advance a key cosmological method which will be applied to the top-rated ground-based project in the Astro2020 decadal survey, LSST. Weak lensing tomography is one of the key science drivers behind LSST. CO-I Clowe is on the weak lensing LSST committee, and senior scientist on this project, at FNAL James Annis, plays a leading role in the DES. This project has built on successful proposals to obtain ground-based imaging for the cluster sample. By 1 Jan, it is anticipated the project will have accumulated complete 5-color photometry on 30 (or about 1/3) of the targeted cluster sample (public webpage for the survey is available at http://cencos.oamp.fr/DAFT/ and has a current summary of the observational status of various clusters). In all, the project has now been awarded the equivalent of over 60

  7. Crossover between weak antilocalization and weak localization of bulk states in ultrathin Bi₂Se₃ films.

    Science.gov (United States)

    Wang, Huichao; Liu, Haiwen; Chang, Cui-Zu; Zuo, Huakun; Zhao, Yanfei; Sun, Yi; Xia, Zhengcai; He, Ke; Ma, Xucun; Xie, X C; Xue, Qi-Kun; Wang, Jian

    2014-07-24

    We report transport studies on the 5 nm thick Bi₂Se₃ topological insulator films which are grown via molecular beam epitaxy technique. The angle-resolved photoemission spectroscopy data show that the Fermi level of the system lies in the bulk conduction band above the Dirac point, suggesting important contribution of bulk states to the transport results. In particular, the crossover from weak antilocalization to weak localization in the bulk states is observed in the parallel magnetic field measurements up to 50 Tesla. The measured magneto-resistance exhibits interesting anisotropy with respect to the orientation of parallel magnetic field B// and the current I, signifying intrinsic spin-orbit coupling in the Bi₂Se₃ films. Our work directly shows the crossover of quantum interference effect in the bulk states from weak antilocalization to weak localization. It presents an important step toward a better understanding of the existing three-dimensional topological insulators and the potential applications of nano-scale topological insulator devices.

  8. Pulse-shaping strategies in short-pulse fiber amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Schimpf, Damian Nikolaus

    2010-02-09

    Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

  9. Pulsed depressed collector

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Mark A

    2015-11-03

    A high power RF device has an electron beam cavity, a modulator, and a circuit for feed-forward energy recovery from a multi-stage depressed collector to the modulator. The electron beam cavity include a cathode, an anode, and the multi-stage depressed collector, and the modulator is configured to provide pulses to the cathode. Voltages of the electrode stages of the multi-stage depressed collector are allowed to float as determined by fixed impedances seen by the electrode stages. The energy recovery circuit includes a storage capacitor that dynamically biases potentials of the electrode stages of the multi-stage depressed collector and provides recovered energy from the electrode stages of the multi-stage depressed collector to the modulator. The circuit may also include a step-down transformer, where the electrode stages of the multi-stage depressed collector are electrically connected to separate taps on the step-down transformer.

  10. Nanofabrication with Pulsed Lasers

    Directory of Open Access Journals (Sweden)

    Kabashin AV

    2010-01-01

    Full Text Available Abstract An overview of pulsed laser-assisted methods for nanofabrication, which are currently developed in our Institute (LP3, is presented. The methods compass a variety of possibilities for material nanostructuring offered by laser–matter interactions and imply either the nanostructuring of the laser-illuminated surface itself, as in cases of direct laser ablation or laser plasma-assisted treatment of semiconductors to form light-absorbing and light-emitting nano-architectures, as well as periodic nanoarrays, or laser-assisted production of nanoclusters and their controlled growth in gaseous or liquid medium to form nanostructured films or colloidal nanoparticles. Nanomaterials synthesized by laser-assisted methods have a variety of unique properties, not reproducible by any other route, and are of importance for photovoltaics, optoelectronics, biological sensing, imaging and therapeutics.

  11. Capacitor discharge pulse analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Michael Sean; Griffiths, Stewart K.; Tanner, Danelle Mary

    2013-08-01

    Capacitors used in firing sets and other high discharge current applications are discharge tested to verify performance of the capacitor against the application requirements. Parameters such as capacitance, inductance, rise time, pulse width, peak current and current reversal must be verified to ensure that the capacitor will meet the application needs. This report summarizes an analysis performed on the discharge current data to extract these parameters by fitting a second-order system model to the discharge data and using this fit to determine the resulting performance metrics. Details of the theory and implementation are presented. Using the best-fit second-order system model to extract these metrics results in less sensitivity to noise in the measured data and allows for direct extraction of the total series resistance, inductance, and capacitance.

  12. Critical types of Krasnoselskii fixed point theorems in weak topologies

    African Journals Online (AJOL)

    In this note, by means of the technique of measures of weak noncompactness, we establish a generalized form of fixed point theorem for the sum of T + S in weak topology setups of a metrizable locally convex space, where S is not weakly compact, I − T allows to be noninvertible, and T is not necessarily continuous.

  13. The influence of weak impacts on certain processes of nanotechnology

    Science.gov (United States)

    Tupik, V. A.; Margolin, V. I.; Potekhin, M. S.

    2017-07-01

    The article deals with the influence of weak and super weak impacts on certain technological processes in nanotechnology related to the synthesis of nanoscale films and coatings. We also touch upon the impacts of weak diffraction fields of complex shape on the formation of fractal films and coatings.

  14. NMR in pulsed magnetic field

    KAUST Repository

    Abou-Hamad, Edy

    2011-09-01

    Nuclear magnetic resonance (NMR) experiments in pulsed magnetic fields up to 30.4 T focused on 1H and 93Nb nuclei are reported. Here we discuss the advantage and limitation of pulsed field NMR and why this technique is able to become a promising research tool. © 2011 Elsevier Inc. All Rights Reserved.

  15. Electrode cartridge for pulse welding

    Energy Technology Data Exchange (ETDEWEB)

    Bonnen, John Joseph Francis; Golovashchenko, Sergey Fedorovich; Mamutov, Alexander; Maison, Lloyd Douglas

    2017-06-14

    A cartridge assembly for a tool includes a cartridge body or casing that contains a conductor. A conductor is connected to a pulse generator or source of stored charge that is discharged to vaporize the conductor and create an electro-hydraulic or electro-magnetic shockwave that is used to impact or pulse weld two parts together.

  16. Pulse Characteristic Curves of Vidicons,

    Science.gov (United States)

    microamps, and in vidicons with heterotransition screens, up to 10 microamps. The use of static modulation characteristic curves of vidicons for the...determination of the pulse beam current can lead to an error > 100%. With the help of pulse-modulation characteristic curves, it is possible to obtain the

  17. Numerical investigation of trichel pulse of negative corona discharge in N2–O2 mixture

    Science.gov (United States)

    Xia, Qing; Zhang, Yu; Jiang, Zhaorui; Wang, Ronggang; Ouyang, Jiting

    2017-12-01

    Trichel pulse of negative corona discharge in atmospheric air is investigated numerically using a 2D fluid model. The model consists of a hyperbolic cathode tip and a plane anode, and considers 11 kinds of particles and the most important interactions among them. The spatio-temporal evolution of charged species and the electric field are evaluated during the pulse process. During the pulse rising edge, the positive ions accumulate ahead of the tip forming the temporal cathode sheath, significantly enhancing the local field. In the pulse decay edge, the temporal sheath collapses and the discharge falls back to a low-current mode. In the pulse interval, the discharge does not cease but sustains weakly until the next pulse. The location of the temporal sheath is independent of the averaged value during the Trichel pulse regime and also the same with that in a normal glow regime, which determines a nearly constant pulse rising time at given configurations. However, a smaller tip radius will lead to their decrease. The effect of negative ions on the pulse process is studied by adjusting the attachment rates. It indicates that the negative ions are actually not necessary in the Trichel pulse process, but will influence the pulse waveform significantly.

  18. Characterization of fast photoelectron packets in weak and strong laser fields in ultrafast electron microscopy.

    Science.gov (United States)

    Plemmons, Dayne A; Tae Park, Sang; Zewail, Ahmed H; Flannigan, David J

    2014-11-01

    The development of ultrafast electron microscopy (UEM) and variants thereof (e.g., photon-induced near-field electron microscopy, PINEM) has made it possible to image atomic-scale dynamics on the femtosecond timescale. Accessing the femtosecond regime with UEM currently relies on the generation of photoelectrons with an ultrafast laser pulse and operation in a stroboscopic pump-probe fashion. With this approach, temporal resolution is limited mainly by the durations of the pump laser pulse and probe electron packet. The ability to accurately determine the duration of the electron packets, and thus the instrument response function, is critically important for interpretation of dynamics occurring near the temporal resolution limit, in addition to quantifying the effects of the imaging mode. Here, we describe a technique for in situ characterization of ultrashort electron packets that makes use of coupling with photons in the evanescent near-field of the specimen. We show that within the weakly-interacting (i.e., low laser fluence) regime, the zero-loss peak temporal cross-section is precisely the convolution of electron packet and photon pulse profiles. Beyond this regime, we outline the effects of non-linear processes and show that temporal cross-sections of high-order peaks explicitly reveal the electron packet profile, while use of the zero-loss peak becomes increasingly unreliable. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Forensic bitemark identification: weak foundations, exaggerated claims

    Science.gov (United States)

    Saks, Michael J.; Albright, Thomas; Bohan, Thomas L.; Bierer, Barbara E.; Bowers, C. Michael; Bush, Mary A.; Bush, Peter J.; Casadevall, Arturo; Cole, Simon A.; Denton, M. Bonner; Diamond, Shari Seidman; Dioso-Villa, Rachel; Epstein, Jules; Faigman, David; Faigman, Lisa; Fienberg, Stephen E.; Garrett, Brandon L.; Giannelli, Paul C.; Greely, Henry T.; Imwinkelried, Edward; Jamieson, Allan; Kafadar, Karen; Kassirer, Jerome P.; Koehler, Jonathan ‘Jay’; Korn, David; Mnookin, Jennifer; Morrison, Alan B.; Murphy, Erin; Peerwani, Nizam; Peterson, Joseph L.; Risinger, D. Michael; Sensabaugh, George F.; Spiegelman, Clifford; Stern, Hal; Thompson, William C.; Wayman, James L.; Zabell, Sandy; Zumwalt, Ross E.

    2016-01-01

    Abstract Several forensic sciences, especially of the pattern-matching kind, are increasingly seen to lack the scientific foundation needed to justify continuing admission as trial evidence. Indeed, several have been abolished in the recent past. A likely next candidate for elimination is bitemark identification. A number of DNA exonerations have occurred in recent years for individuals convicted based on erroneous bitemark identifications. Intense scientific and legal scrutiny has resulted. An important National Academies review found little scientific support for the field. The Texas Forensic Science Commission recently recommended a moratorium on the admission of bitemark expert testimony. The California Supreme Court has a case before it that could start a national dismantling of forensic odontology. This article describes the (legal) basis for the rise of bitemark identification and the (scientific) basis for its impending fall. The article explains the general logic of forensic identification, the claims of bitemark identification, and reviews relevant empirical research on bitemark identification—highlighting both the lack of research and the lack of support provided by what research does exist. The rise and possible fall of bitemark identification evidence has broader implications—highlighting the weak scientific culture of forensic science and the law's difficulty in evaluating and responding to unreliable and unscientific evidence. PMID:28852538

  20. Forensic bitemark identification: weak foundations, exaggerated claims.

    Science.gov (United States)

    Saks, Michael J; Albright, Thomas; Bohan, Thomas L; Bierer, Barbara E; Bowers, C Michael; Bush, Mary A; Bush, Peter J; Casadevall, Arturo; Cole, Simon A; Denton, M Bonner; Diamond, Shari Seidman; Dioso-Villa, Rachel; Epstein, Jules; Faigman, David; Faigman, Lisa; Fienberg, Stephen E; Garrett, Brandon L; Giannelli, Paul C; Greely, Henry T; Imwinkelried, Edward; Jamieson, Allan; Kafadar, Karen; Kassirer, Jerome P; Koehler, Jonathan 'Jay'; Korn, David; Mnookin, Jennifer; Morrison, Alan B; Murphy, Erin; Peerwani, Nizam; Peterson, Joseph L; Risinger, D Michael; Sensabaugh, George F; Spiegelman, Clifford; Stern, Hal; Thompson, William C; Wayman, James L; Zabell, Sandy; Zumwalt, Ross E

    2016-12-01

    Several forensic sciences, especially of the pattern-matching kind, are increasingly seen to lack the scientific foundation needed to justify continuing admission as trial evidence. Indeed, several have been abolished in the recent past. A likely next candidate for elimination is bitemark identification. A number of DNA exonerations have occurred in recent years for individuals convicted based on erroneous bitemark identifications. Intense scientific and legal scrutiny has resulted. An important National Academies review found little scientific support for the field. The Texas Forensic Science Commission recently recommended a moratorium on the admission of bitemark expert testimony. The California Supreme Court has a case before it that could start a national dismantling of forensic odontology. This article describes the (legal) basis for the rise of bitemark identification and the (scientific) basis for its impending fall. The article explains the general logic of forensic identification, the claims of bitemark identification, and reviews relevant empirical research on bitemark identification-highlighting both the lack of research and the lack of support provided by what research does exist. The rise and possible fall of bitemark identification evidence has broader implications-highlighting the weak scientific culture of forensic science and the law's difficulty in evaluating and responding to unreliable and unscientific evidence.

  1. Atomic Inference from Weak Gravitational Lensing Data

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Phil; /KIPAC, Menlo Park

    2005-12-14

    We present a novel approach to reconstructing the projected mass distribution from the sparse and noisy weak gravitational lensing shear data. The reconstructions are regularized via the knowledge gained from numerical simulations of clusters, with trial mass distributions constructed from n NFW profile ellipsoidal components. The parameters of these ''atoms'' are distributed a priori as in the simulated clusters. Sampling the mass distributions from the atom parameter probability density function allows estimates of the properties of the mass distribution to be generated, with error bars. The appropriate number of atoms is inferred from the data itself via the Bayesian evidence, and is typically found to be small, reecting the quality of the data. Ensemble average mass maps are found to be robust to the details of the noise realization, and succeed in recovering the demonstration input mass distribution (from a realistic simulated cluster) over a wide range of scales. As an application of such a reliable mapping algorithm, we comment on the residuals of the reconstruction and the implications for predicting convergence and shear at specific points on the sky.

  2. Pulse shaping using a spatial light modulator

    CSIR Research Space (South Africa)

    Botha, N

    2009-07-01

    Full Text Available Femtosecond pulse shaping can be done by different kinds of pulse shapers, such as liquid crystal spatial light modulators (LC SLM), acousto optic modulators (AOM) and deformable and movable mirrors. A few applications where pulse shaping...

  3. Strong and Weak Chaos in Weakly Nonintegrable Many-Body Hamiltonian Systems

    Science.gov (United States)

    Mulansky, M.; Ahnert, K.; Pikovsky, A.; Shepelyansky, D. L.

    2011-12-01

    We study properties of chaos in generic one-dimensional nonlinear Hamiltonian lattices comprised of weakly coupled nonlinear oscillators by numerical simulations of continuous-time systems and symplectic maps. For small coupling, the measure of chaos is found to be proportional to the coupling strength and lattice length, with the typical maximal Lyapunov exponent being proportional to the square root of coupling. This strong chaos appears as a result of triplet resonances between nearby modes. In addition to strong chaos we observe a weakly chaotic component having much smaller Lyapunov exponent, the measure of which drops approximately as a square of the coupling strength down to smallest couplings we were able to reach. We argue that this weak chaos is linked to the regime of fast Arnold diffusion discussed by Chirikov and Vecheslavov. In disordered lattices of large size we find a subdiffusive spreading of initially localized wave packets over larger and larger number of modes. The relations between the exponent of this spreading and the exponent in the dependence of the fast Arnold diffusion on coupling strength are analyzed. We also trace parallels between the slow spreading of chaos and deterministic rheology.

  4. Pulse source requirements for OTDM systems

    DEFF Research Database (Denmark)

    Clausen, Anders; Poulsen, Henrik Nørskov; Oxenløwe, Leif Katsuo

    2003-01-01

    A simulation model for investigating the impact of incoherent crosstalk due to pulse tail overlapping is proposed. Requirements to pulse width and pulse tail extinction ratio introducing a maximum of 1 dB penalty is extracted.......A simulation model for investigating the impact of incoherent crosstalk due to pulse tail overlapping is proposed. Requirements to pulse width and pulse tail extinction ratio introducing a maximum of 1 dB penalty is extracted....

  5. Bomb pulse biology

    Energy Technology Data Exchange (ETDEWEB)

    Falso, Miranda J. Sarachine [Center for Accelerator Mass Spectrometry, Mail Stop L-397, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States); Buchholz, Bruce A., E-mail: buchholz2@llnl.gov [Center for Accelerator Mass Spectrometry, Mail Stop L-397, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States)

    2013-01-15

    The past decade has seen an explosion in use of the {sup 14}C bomb pulse to do fundamental cell biology. Studies in the 1960s used decay counting to measure tissue turnover when the atmospheric {sup 14}C/C concentration was changing rapidly. Today bulk tissue measurements are of marginal interest since most of the carbon in the tissue resides in proteins, lipids and carbohydrates that turn over rapidly. Specific cell types with specialized functions are the focus of cell turnover investigations. Tissue samples need to be fresh or frozen. Fixed or preserved samples contain petroleum-derived carbon that has not been successfully removed. Cell or nuclear surface markers are used to sort specific cell types, typically by fluorescence-activated cell sorting (FACS). Specific biomolecules need to be isolated with high purity and accelerator mass spectrometry (AMS) measurements must accommodate samples that generally contain less than 40 {mu}g of carbon. Furthermore, all separations must not add carbon to the sample. Independent means such as UV absorbance must be used to confirm molecule purity. Approaches for separating specific proteins and DNA and combating contamination of undesired molecules are described.

  6. Tests of the weak equivalence principle

    Science.gov (United States)

    Speake, C. C.; Will, C. M.

    2012-09-01

    The Einstein equivalence principle is the foundation for general relativity and all metric theories of gravity. Of its three tenets—the equality of acceleration of test bodies, or weak equivalence principle; the validity of Lorentz invariance in local freely falling frames; and the position invariance of local physical laws—the weak equivalence principle has played the most important role historically, and continues to be a focus of intense theoretical and experimental investigation. From the probably apocryphal 16th century demonstrations by Galileo at Pisa's leaning tower to the sensitive torsion-balance measurements of today (both pictured on the cover of this issue), this principle, dubbed WEP, has been crucial to the development of gravitation theory. The universality of the rate of acceleration of all types of matter in a gravitational field can be taken as evidence that gravitation is fundamentally determined by the geometry, or metric, of spacetime. Newton began his magnum opus 'The Principia' with a discussion of WEP and his experiments to verify it, while Einstein took WEP for granted in his construction of general relativity, never once referring to the epochal experiments by Baron Eötvös. The classic 1964 experiment of Roll, Krotkov and Dicke ushered in the modern era of high-precision tests, and the search for a 'fifth force' during the late 1980s (instigated, ironically, by purported anomalies in Eötvös's old data) caused the enterprise to pivot from pure tests of the foundation of GR to searches for new physics beyond the standard model of the non-gravitational interactions. Today, the next generation of experimental tests of WEP are being prepared for launch or are being developed, with the goal of reaching unprecedented levels of sensitivity, in search of signatures of interactions inspired by string theory, extra dimensions and other concepts from the world of high-energy physics. At the same time observations continue using lunar laser

  7. Planckian axions and the Weak Gravity Conjecture

    Energy Technology Data Exchange (ETDEWEB)

    Bachlechner, Thomas C.; Long, Cody; McAllister, Liam [Department of Physics, Cornell University,Ithaca, NY 14853 (United States)

    2016-01-18

    Several recent works http://dx.doi.org/10.1088/1475-7516/2015/09/020, http://dx.doi.org/10.1007/JHEP08(2015)032, http://dx.doi.org/10.1007/JHEP10(2015)023 have claimed that the Weak Gravity Conjecture (WGC) excludes super-Planckian displacements of axion fields, and hence large-field axion inflation, in the absence of monodromy. We argue that in theories with N≫1 axions, super-Planckian axion diameters D are readily allowed by the WGC. We clarify the nontrivial relationship between the kinetic matrix K — unambiguously defined by its form in a Minkowski-reduced basis — and the diameter of the axion fundamental domain, emphasizing that in general the diameter is not solely determined by the eigenvalues f{sub 1}{sup 2}≤…≤f{sub N}{sup 2} of K: the orientations of the eigenvectors with respect to the identifications imposed by instantons must be incorporated. In particular, even if one were to impose the condition f{sub N}M{sub pl} does not immediately imply the existence of unsuppressed higher harmonic contributions to the potential. Finally, we argue that in effective axion-gravity theories, the zero-form version of the WGC can be satisfied by gravitational instantons that make negligible contributions to the potential.

  8. [Dynamic pulse signal acquisition and processing].

    Science.gov (United States)

    Zhang, Aihua; Chou, Yongxin

    2012-03-01

    In order to obtain and process pulse signal in real-time, the integer coefficients notch, low-pass filters and an envelope filtering method were designed in consideration of the characteristics of disturbances in pulse signal and then were verified by MATLAB. The pulse signal was processed on DSP in time domain and frequency domain after simplifying the programming. The pulse wave height and pulse rate were calculated in real-time, and the pulse signal's spectrum was illustrated by FFT. The results show that the filters can effectively suppress the interference in pulse signal, and the system can detect and analyze the dynamic pulse signal in real-time.

  9. Pulsed ultrasonic stir welding method

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.

  10. Pulsed light and pulsed electric field for foods and eggs.

    Science.gov (United States)

    Dunn, J

    1996-09-01

    Two new technologies for use in the food industry are described. The first method discussed uses intense pulse of light. This pulsed light (PureBright) process uses short duration flashes of broad spectrum "white" light to kill all exposed microorganisms, including vegetative bacteria, microbial and fungal spores, viruses, and protozoan oocysts. Each pulse, or flash, of light lasts only a few hundred millionths of a second (i.e., a few hundred microseconds). The intensity of each flash of light is about 20,000 times the intensity of sunlight at the earth's surface. The flashes are typically applied at a rate of about one to tens of flashes per second. For most applications, a few flashes applied in a fraction of a second provide an effective treatment. High microbial kill can be achieved, for example, on the surfaces of packaging materials, on packaging and processing equipment, foods, and medical devices as well as on many other surfaces. In addition, some bulk materials such as water and air that allow penetration of the light can be sterilized. The results of tests to measure the effects of pulsed light on Salmonella enteritiditis on eggs are presented. The second method discussed uses multiple, short duration, high intensity electric field pulses to kill vegetative microorganisms in pumpable products. This pulsed electric field (or CoolPure) process can be applied at modest temperatures at which no appreciable thermal damage occurs and the original taste, color, texture, and functionality of products can be retained.

  11. Localized wave pulses in the keyport experiment

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, D.H.; Lewis, D.K.

    1998-02-17

    Localized wave (LW) pulses were produced using a standard Navy array in the anechoic tank at Navy Underwater Weapons Center (NUWC) Keyport. The LW pulses used were the MPS pulse first derived by Ziolkowski, and a new type of pulse based on a superposition of Gaussian beam modes. This new type is motivated by a desire to make a comparison of the MPS pulse with another broad band pulse built from solutions to the wave equation. The superposed Gaussian pulse can be described by parameters which are analogous to those describing the MPS pulse. We compare the directivity patternsand the axial energy decay between the pulses. We find the behavior of the pulses to be similar so that the superposed Gaussian could be another candidate in the class of low diffractive pulses known as localized waves.

  12. Prefire identification for pulse power systems

    Energy Technology Data Exchange (ETDEWEB)

    Longmire, Jerry L. (Los Alamos, NM); Thuot, Michael E. (Espanola, NM); Warren, David S. (Los Alamos, NM)

    1985-01-01

    Prefires in a high-power, high-frequency, multi-stage pulse generator are detected by a system having an EMI shielded pulse timing transmitter associated with and tailored to each stage of the pulse generator. Each pulse timing transmitter upon detection of a pulse triggers a laser diode to send an optical signal through a high frequency fiber optic cable to a pulse timing receiver which converts the optical signal to an electrical pulse. The electrical pulses from all pulse timing receivers are fed through an OR circuit to start a time interval measuring device and each electrical pulse is used to stop an individual channel in the measuring device thereby recording the firing sequence of the multi-stage pulse generator.

  13. Prefire identification for pulse power systems

    Energy Technology Data Exchange (ETDEWEB)

    Longmire, J. L.; Thuot, M. E.; Warren, D. S.

    1985-04-09

    Prefires in a high-power, high-frequency, multi-stage pulse generator are detected by a system having an EMI shielded pulse timing transmitter associated with and tailored to each stage of the pulse generator. Each pulse timing transmitter upon detection of a pulse triggers a laser diode to send an optical signal through a high frequency fiber optic cable to a pulse timing receiver which converts the optical signal to an electrical pulse. The electrical pulses from all pulse timing receivers are fed through an OR circuit to start a time interval measuring device and each electrical pulse is used to stop an individual channel in the measuring device thereby recording the firing sequence of the multi-stage pulse generator.

  14. Prefire identification for pulse-power systems

    Energy Technology Data Exchange (ETDEWEB)

    Longmire, J.L.; Thuot, M.E.; Warren, D.S.

    1982-08-23

    Prefires in a high-power, high-frequency, multi-stage pulse generator are detected by a system having an EMI shielded pulse timing transmitter associated with and tailored to each stage of the pulse generator. Each pulse timing transmitter upon detection of a pulse triggers a laser diode to send an optical signal through a high frequency fiber optic cable to a pulse timing receiver which converts the optical signal to an electrical pulse. The electrical pulses from all pulse timing receivers are fed through an OR circuit to start a time interval measuring device and each electrical pulse is used to stop an individual channel in the measuring device thereby recording the firing sequence of the multi-stage pulse generator.

  15. Luminal pulse velocity in a superluminal medium

    Science.gov (United States)

    Amano, Heisuke; Tomita, Makoto

    2015-12-01

    To investigate the physical meaning of pulse peak in fast and slow light media, we investigated propagation of differently shaped pulses experimentally, controlling the sharpness of the pulse peak. Symmetric behavior with respect to fast and slow light was observed in traditional Gaussian pulses; that is, propagated pulses were advanced or delayed, respectively, whereas the pulse shape remained unchanged. This symmetry broke down when the pulse peak was sharpened; in the fast light medium, the sharp pulse peak propagated with luminal velocity, and the transmitted pulse deformed into a characteristic asymmetric profile. In contrast, in the slow light medium, a time-delayed smooth peak appeared with a bending point at t =0 . This symmetry breaking with respect to fast and slow light is a universal characteristic of pulse propagation in causal dispersive systems. The sharp pulse peak can be recognized as a bending nonanalytical point and may be capable of transferring information.

  16. Pulse oximetry for perioperative monitoring

    DEFF Research Database (Denmark)

    Pedersen, Tom; Nicholson, Amanda; Hovhannisyan, Karen

    2014-01-01

    of hypoxaemia reduce morbidity and mortality in the perioperative period.3. Use of pulse oximetry per se reduces morbidity and mortality in the perioperative period.4. Use of pulse oximetry reduces unplanned respiratory admissions to the intensive care unit (ICU), decreases the length of ICU readmission or both....... SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 5), MEDLINE (1966 to June 2013), EMBASE (1980 to June 2013), CINAHL (1982 to June 2013), ISI Web of Science (1956 to June 2013), LILACS (1982 to June 2013) and databases of ongoing trials; we also....... Results indicated that hypoxaemia was reduced in the pulse oximetry group, both in the operating theatre and in the recovery room. During observation in the recovery room, the incidence of hypoxaemia in the pulse oximetry group was 1.5 to three times less. Postoperative cognitive function was independent...

  17. All about Heart Rate (Pulse)

    Science.gov (United States)

    ... result of taking a drug such as a beta blocker . A lower heart rate is also common for ... 100. Medication use: Meds that block your adrenaline (beta blockers) tend to slow your pulse, while too much ...

  18. Next generation Chirped Pulse Amplification

    Energy Technology Data Exchange (ETDEWEB)

    Nees, J.; Biswal, S.; Mourou, G. [Univ. Michigan, Center for Ultrafast Optical Science, Ann Arbor, MI (United States); Nishimura, Akihiko; Takuma, Hiroshi

    1998-03-01

    The limiting factors of Chirped Pulse Amplification (CPA) are discussed and experimental results of CPA in Yb:glass regenerative amplifier are given. Scaling of Yb:glass to the petawatt level is briefly discussed. (author)

  19. Proximal Limb Weakness Reverting After CSF Diversion In Intracranial Hypertension

    Directory of Open Access Journals (Sweden)

    Sinha S

    2005-01-01

    Full Text Available We report about two young girls who developed progressive visual failure secondary to increased intracranial pressure and had significant proximal muscle weakness of limbs. Patients with elevated intracranial pressure (ICP may present with "false localizing signs", besides having headache, vomiting and papilledema. Radicular pain as a manifestation of raised ICP is rare and motor weakness attributable to polyradiculopathy is exceptional. Two patients with increased intracranial pressure without lateralizing signs′ had singnificant muscle weakness. Clinical evaluation and laboratory tests did not disclose any other cause for weakness. Following theco-peritoneal shunt, in both patients, there was variable recovery of vision but the proximal weakness and symptoms of elevated ICP improved rapidly. Recognition of this uncommon manifestation of raised ICP may obviate the need for unnecessary investigation and reduce morbidity due to weakness by CSF diversion procedure.

  20. Experimental and theoretical study of Al plasma under femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Komarov, P S; Ashitkov, S I; Ovchinnikov, A V; Sitnikov, D S; Veysman, M E; Levashov, P R; Povarnitsyn, M E; Agranat, M B; Andreev, N E; Khishchenko, K V; Fortov, V E [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya St. 13, Bd. 2, Moscow 125412 (Russian Federation)], E-mail: bme@ihed.ras.ru

    2009-05-29

    The amplitude and phase of the complex reflection coefficient of a weak probe laser pulse from strongly coupled Al plasma created on the surface of a metallic target by pump femtosecond laser pulses with intensities I {approx}< 10{sup 15} W cm{sup -2} were measured using femtosecond interference microscopy. A theoretical model developed for the interaction of intense ultrashort laser pulses with solid targets on the basis of a two-temperature equation of state for an irradiated substance was used for numerical simulations of the dynamics of the formation and expansion of the plasma. A comparison of the experimental data with the simulated results shows that the model is suitable up to I {approx} 10{sup 14} W cm{sup -2}. At higher intensities of the heating laser pulse, lower values of the reflection coefficient amplitude of Al plasma are observed in the experiment.

  1. Pulsed ultrasonic stir welding system

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    An ultrasonic stir welding system includes a welding head assembly having a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. During a welding operation, ultrasonic pulses are applied to the rod as it rotates about its longitudinal axis. The ultrasonic pulses are applied in such a way that they propagate parallel to the longitudinal axis of the rod.

  2. Pulsed feedback defers cellular differentiation.

    Directory of Open Access Journals (Sweden)

    Joe H Levine

    2012-01-01

    Full Text Available Environmental signals induce diverse cellular differentiation programs. In certain systems, cells defer differentiation for extended time periods after the signal appears, proliferating through multiple rounds of cell division before committing to a new fate. How can cells set a deferral time much longer than the cell cycle? Here we study Bacillus subtilis cells that respond to sudden nutrient limitation with multiple rounds of growth and division before differentiating into spores. A well-characterized genetic circuit controls the concentration and phosphorylation of the master regulator Spo0A, which rises to a critical concentration to initiate sporulation. However, it remains unclear how this circuit enables cells to defer sporulation for multiple cell cycles. Using quantitative time-lapse fluorescence microscopy of Spo0A dynamics in individual cells, we observed pulses of Spo0A phosphorylation at a characteristic cell cycle phase. Pulse amplitudes grew systematically and cell-autonomously over multiple cell cycles leading up to sporulation. This pulse growth required a key positive feedback loop involving the sporulation kinases, without which the deferral of sporulation became ultrasensitive to kinase expression. Thus, deferral is controlled by a pulsed positive feedback loop in which kinase expression is activated by pulses of Spo0A phosphorylation. This pulsed positive feedback architecture provides a more robust mechanism for setting deferral times than constitutive kinase expression. Finally, using mathematical modeling, we show how pulsing and time delays together enable "polyphasic" positive feedback, in which different parts of a feedback loop are active at different times. Polyphasic feedback can enable more accurate tuning of long deferral times. Together, these results suggest that Bacillus subtilis uses a pulsed positive feedback loop to implement a "timer" that operates over timescales much longer than a cell cycle.

  3. Artistic Representation with Pulsed Holography

    Science.gov (United States)

    Ishii, S.

    2013-02-01

    This thesis describes artistic representation through pulsed holography. One of the prevalent practical problems in making holograms is object movement. Any movement of the object or film, including movement caused by acoustic vibration, has the same fatal results. One way of reducing the chance of movement is by ensuring that the exposure is very quick; using a pulsed laser can fulfill this objective. The attractiveness of using pulsed laser is based on the variety of materials or objects that can be recorded (e.g., liquid material or instantaneous scene of a moving object). One of the most interesting points about pulsed holograms is that some reconstructed images present us with completely different views of the real world. For example, the holographic image of liquid material does not appear fluid; it looks like a piece of hard glass that would produce a sharp sound upon tapping. In everyday life, we are unfamiliar with such an instantaneous scene. On the other hand, soft-textured materials such as a feather or wool differ from liquids when observed through holography. Using a pulsed hologram, we can sense the soft touch of the object or material with the help of realistic three-dimensional (3-D) images. The images allow us to realize the sense of touch in a way that resembles touching real objects. I had the opportunity to use a pulsed ruby laser soon after I started to work in the field of holography in 1979. Since then, I have made pulsed holograms of activities, including pouring water, breaking eggs, blowing soap bubbles, and scattering feathers and popcorn. I have also created holographic art with materials and objects, such as silk fiber, fabric, balloons, glass, flowers, and even the human body. Whenever I create art, I like to present the spectator with a new experience in perception. Therefore, I would like to introduce my experimental artwork through those pulsed holograms.

  4. Optical pulses, lasers, measuring techniques

    CERN Document Server

    Früngel, Frank B A

    1965-01-01

    High Speed Pulse Technology: Volume II: Optical Pulses - Lasers - Measuring Techniques focuses on the theoretical and engineering problems that result from the capacitor discharge technique.This book is organized into three main topics: light flash production from a capacitive energy storage; signal transmission and ranging systems by capacitor discharges and lasers; and impulse measuring technique. This text specifically discusses the air spark under atmospheric conditions, industrial equipment for laser flashing, and claims for light transmitting system. The application of light impulse sign

  5. Pulsed laser ablation of copper

    Science.gov (United States)

    Jordan, R.; Cole, D.; Lunney, J. G.; Mackay, K.; Givord, D.

    1995-02-01

    The laser ablation of copper with a 532 nm, 6 ns laser has been investigated in the regime normally used for pulsed laser deposition. The ablation depth per pulse and the flux and energy distribution of the ions in the plume were measured and compared to the deposition rate as measured by a quartz microbalance. These measurements were compared with an analytic model of ablation via a laser sustained plasma. It is shown that self-sputtering of the growing film is significant.

  6. Information flow between weakly interacting lattices of coupled maps

    Energy Technology Data Exchange (ETDEWEB)

    Dobyns, York [PEAR, Princeton University, Princeton, NJ 08544-5263 (United States); Atmanspacher, Harald [Institut fuer Grenzgebiete der Psychologie und Psychohygiene, Wilhelmstr. 3a, 79098 Freiburg (Germany)]. E-mail: haa@igpp.de

    2006-05-15

    Weakly interacting lattices of coupled maps can be modeled as ordinary coupled map lattices separated from each other by boundary regions with small coupling parameters. We demonstrate that such weakly interacting lattices can nevertheless have unexpected and striking effects on each other. Under specific conditions, particular stability properties of the lattices are significantly influenced by their weak mutual interaction. This observation is tantamount to an efficacious information flow across the boundary.

  7. Kramers systems with weak spin-dependent interactions

    Energy Technology Data Exchange (ETDEWEB)

    Radwanski, R.J. [Inst. of Physics and Informatics, Pedagogical University, 30-084, Krakow (Poland)]|[Center for Solid State Physics, Sw. Filip 5, 31-150, Krakow (Poland)

    1995-02-09

    Magnetic properties of a paramagnetic Kramers f{sup 3} subsystem under charge interactions of the hexagonal symmetry have been examined in the combination with weak spin-dependent (S-D) interactions for the case of the weakly-magnetic charge-formed ground state. The Kramers systems with weak S-D interactions exhibit particular phenomena like large specific heat at low temperatures. ((orig.)).

  8. Square pulse linear transformer driver

    Directory of Open Access Journals (Sweden)

    A. A. Kim

    2012-04-01

    Full Text Available The linear transformer driver (LTD technological approach can result in relatively compact devices that can deliver fast, high current, and high-voltage pulses straight out of the LTD cavity without any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The usual LTD architecture [A. A. Kim, M. G. Mazarakis, V. A. Sinebryukhov, B. M. Kovalchuk, V. A. Vizir, S. N Volkov, F. Bayol, A. N. Bastrikov, V. G. Durakov, S. V. Frolov, V. M. Alexeenko, D. H. McDaniel, W. E. Fowler, K. LeCheen, C. Olson, W. A. Stygar, K. W. Struve, J. Porter, and R. M. Gilgenbach, Phys. Rev. ST Accel. Beams 12, 050402 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050402; M. G. Mazarakis, W. E. Fowler, A. A. Kim, V. A. Sinebryukhov, S. T. Rogowski, R. A. Sharpe, D. H. McDaniel, C. L. Olson, J. L. Porter, K. W. Struve, W. A. Stygar, and J. R. Woodworth, Phys. Rev. ST Accel. Beams 12, 050401 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050401] provides sine shaped output pulses that may not be well suited for some applications like z-pinch drivers, flash radiography, high power microwaves, etc. A more suitable power pulse would have a flat or trapezoidal (rising or falling top. In this paper, we present the design and first test results of an LTD cavity that generates such a type of output pulse by including within its circular array a number of third harmonic bricks in addition to the main bricks. A voltage adder made out of a square pulse cavity linear array will produce the same shape output pulses provided that the timing of each cavity is synchronized with the propagation of the electromagnetic pulse.

  9. River water remediation using pulsed corona, pulsed spark or ozonation

    Energy Technology Data Exchange (ETDEWEB)

    Izdebski, T.; Dors, M. [Polish Academy of Sciences, Szewalski Inst. of Fluid Flow Machiney, Fiszera (Poland). Centre for Plasma and Laser Engineering; Mizeraczyk, J. [Polish Academy of Sciences, Szewalski Inst. of Fluid Flow Machiney, Fiszera (Poland). Centre for Plasma and Laser Engineering; Gdynia Maritime Univ., Morska (Poland). Dept. of Marine Electronics

    2010-07-01

    The most common reason for epidemic formation is the pollution of surface and drinking water by wastewater bacteria. Pathogenic microorganisms that form the largest part of this are fecal bacteria, such as escherichia coli (E. coli). Wastewater treatment plants reduce the amount of the fecal bacteria by 1-3 orders of magnitude, depending on the initial number of bacteria. There is a lack of data on waste and drinking water purification by the electrohydraulic discharges method, which causes the destruction and inactivation of viruses, yeast, and bacteria. This paper investigated river water cleaning from microorganisms using pulsed corona, spark discharge and ozonization. The paper discussed the experimental setup and results. It was concluded that ozonization is the most efficient method of water disinfection as compared with pulsed spark and pulsed corona discharges. The pulsed spark discharge in water was capable of killing all microorganism similarly to ozonization, but with much lower energy efficiency. The pulsed corona discharge was found to be the less effective method of water disinfection. 21 refs., 4 figs.

  10. Behavioral studies of the auditory discrimination of paired pulses with identical pulse spacings by a dolphin

    Science.gov (United States)

    Sukhoruchenko, M. N.

    2008-11-01

    For a bottlenose dolphin, the thresholds of discrimination of paired pulses with pulse spacings of 50 1000 μs and different peak values of the second pulse in the test pair are investigated. It is shown that the pair discrimination thresholds depend on both the absolute level of pulses and the ratio between the pulse levels in the standard pair. As the pulse delay in a pair increases, the thresholds monotonically decrease. A possibility of the paired pulse discrimination by the total energy of pulses in a pair is considered for the case of pulse delays both within the critical interval (300 μs) and beyond it.

  11. Comparison of automated and static pulse respiratory mechanics during supported ventilation.

    Science.gov (United States)

    Patel, Alpesh R; Taylor, Susan; Bersten, Andrew D

    2012-06-01

    To compare respiratory mechanics estimated by the (pulse) technique in spontaneously breathing patients during proportional assist ventilation (PAV) with load-adjustable gain factor (PAV+) mode with those measured using the flow-interruption technique during controlled ventilation. Observational study of 21 haemodynamically stable post-cardiac surgery patients with routine weaning from mechanical ventilation (Puritan-Bennett 840 ventilator) in the intensive care unit of a tertiary hospital. Bland-Altman and linear correlation of respiratory system compliance and inspiratory resistance estimated during PAV+ (C(pulse) and R(pulse)) with that measured during controlled mechanical ventilation (C(int) and Rint). C(pulse) overestimated C(int) (67.4 [SD, 27.7] v 51.6 [SD, 9.7] mL/cmH(2)O; P = 0.02), although the correlation between C(int) and C(pulse) was strong. Using the Bland-Altman method, the bias and limits of agreement were outside a clinically useful range. R(pulse) underestimated Rint (9.3 [SD, 3.0] v 11.5 [SD, 3.0] cmH(2)O/L/s; P = 0.02), with a weak positive correlation. Although the bias calculated by the Bland-Altman method was small, the limits of agreement were too large to be clinically useful. Based on these data, respiratory mechanics estimated from the (pulse) technique are too inaccurate to be clinically useful.

  12. Pulsed Corona Discharge Generated By Marx Generator

    Science.gov (United States)

    Sretenovic, G. B.; Obradovic, B. M.; Kovacevic, V. V.; Kuraica, M. M.; Puric J.

    2010-07-01

    The pulsed plasma has a significant role in new environmental protection technologies. As a part of a pulsed corona system for pollution control applications, Marx type repetitive pulse generator was constructed and tested in arrangement with wire-plate corona reactor. We performed electrical measurements, and obtained voltage and current signals, and also power and energy delivered per pulse. Ozone formation by streamer plasma in air was chosen to monitor chemical activity of the pulsed corona discharge.

  13. On n-weak amenability of Rees semigroup algebras

    Indian Academy of Sciences (India)

    semigroups. In this work, we shall consider this class of Banach algebras. We examine the n-weak amenability of some semigroup algebras, and give an easier example of a Banach algebra which is n-weakly amenable if n is odd. Let L1(G) be the group algebra of a locally compact group G (§3.3 of [3]). Then Johnson.

  14. Space group constraints on weak indices in topological insulators

    NARCIS (Netherlands)

    Varjas, D.; De Juan, Fernando; Lu, Yuan Ming

    Lattice translation symmetry gives rise to a large class of "weak" topological insulators (TIs), characterized by translation-protected gapless surface states and dislocation bound states. In this work we show that space group symmetries lead to constraints on the weak topological indices that

  15. Electron Capture Dissociation of Weakly Bound Polypeptide Polycationic Complexes

    DEFF Research Database (Denmark)

    Haselmann, Kim F; Jørgensen, Thomas J D; Budnik, Bogdan A

    2002-01-01

    We have previously reported that, in electron capture dissociation (ECD), rupture of strong intramolecular bonds in weakly bound supramolecular aggregates can proceed without dissociation of weak intermolecular bonds. This is now illustrated on a series of non-specific peptide-peptide dimers...

  16. Perturbated rotational motion of weakly deformable celestial bodies

    Science.gov (United States)

    Barkin, Yu. V.

    The rotation equations of weakly deformable celestial bodies (in canonical and non-canonical Andoyer variables) are developed in detail. A theory of the perturbed rotational motion of an isolated weakly deformable body has been developed. Applications to Earth's rotation theory are given.

  17. Intensive care unit-acquired weakness : Pathophysiology and diagnosis

    NARCIS (Netherlands)

    Witteveen, E.

    2017-01-01

    Many patients on the intensive care unit (ICU) develop generalized muscle weakness. This condition, called intensive care unit- acquired weakness (ICU-AW), is caused by dysfunction or damage of muscles, nerves, or both. ICU-AW is associated with increased short- and long-term morbidity and

  18. On defining soft spaces by weak soft neighborhood systems

    Directory of Open Access Journals (Sweden)

    Taha ÖZTÜRK

    2016-04-01

    Full Text Available In the present paper, we define the concepts of weak soft neighborhood space, soft w^{s}(?,?'-continuous, soft w^{s}-continuous and soft w^{s^{*}}-continuous on weak soft neighborhood spaces. Finally, we introduce their basic properties and some examples.

  19. Secure Authentication from a Weak Key, Without Leaking Information

    NARCIS (Netherlands)

    N.J. Bouman (Niek); S. Fehr (Serge); K.G. Paterson (Kerry)

    2011-01-01

    htmlabstractWe study the problem of authentication based on a weak key in the information-theoretic setting. A key is weak if its min-entropy is an arbitrary small fraction of its bit length. This problem has recently received considerable attention, with different solutions optimizing different

  20. Some Viable Techniques for Assessing and Counselling Cognitive Processing Weakness

    Science.gov (United States)

    Haruna, Abubakar Sadiq

    2016-01-01

    Cognitive Processing weakness (CPW) is a psychological problem that impedes students' ability to learn effectively in a normal school setting. Such weakness may include; auditory, visual, conceptual, sequential, speed and attention processing. This paper therefore examines the basic assessment or diagnostic approaches such as Diagnosis by…

  1. Bunched soliton states in weakly coupled sine-Gordon systems

    DEFF Research Database (Denmark)

    Grønbech-Jensen, N.; Samuelsen, Mogens Rugholm; Lomdahl, P. S.

    1990-01-01

    The interaction between solitons of two weakly coupled sine-Gordon systems is considered. In particular, the stability of bunched states is investigated, and perturbation results are compared with numerical results.......The interaction between solitons of two weakly coupled sine-Gordon systems is considered. In particular, the stability of bunched states is investigated, and perturbation results are compared with numerical results....

  2. Measuring Workload Weak Resilience Signals at a Rail Control Post

    NARCIS (Netherlands)

    Siegel, A.W.; Schraagen, J.M.C.

    2014-01-01

    OCCUPATIONAL APPLICATIONS This article describes an observational study at a rail control post to measure workload weak resilience signals. A weak resilience signal indicates a possible degradation of a system's resilience, which is defined as the ability of a complex socio-technical system to cope

  3. Covenants with Weak Swords: ISO 14001 and Facilities' Environmental Performance

    Science.gov (United States)

    Potoski, Matthew; Prakash, Aseem

    2005-01-01

    Voluntary environmental programs are codes of progressive environmental conduct that firms pledge to adopt. This paper investigates whether ISO 14001, a voluntary program with a weak sword--a weak monitoring and sanctioning mechanism--can mitigate shirking and improve participants' environmental performance. Sponsored by the International…

  4. Diaphragm weakness in pulmonary arterial hypertension: role of sarcomeric dysfunction

    NARCIS (Netherlands)

    Manders, E.; Man, F.S. de; Handoko, M.L.; Westerhof, N.; Hees, H.W.H. van; Stienen, G.J.; Vonk-Noordegraaf, A.; Ottenheijm, C.A.C.

    2012-01-01

    We previously demonstrated that diaphragm muscle weakness is present in experimental pulmonary arterial hypertension (PH). However, the nature of this diaphragm weakness is still unknown. Therefore, the aim of this study was to investigate whether changes at the sarcomeric level contribute to

  5. Measures of weak noncompactness, nonlinear Leray-Schauder ...

    African Journals Online (AJOL)

    In this paper, we establish some new nonlinear Leray-Schauder alternatives for the sum and the product of weakly sequentially continuous operators in Banach algebras satisfying certain sequential condition (P). The main condition in our results is formulated in terms of axiomatic measures of weak noncompactness.

  6. Classical simulations of heavy-ion fusion reactions and weakly ...

    Indian Academy of Sciences (India)

    This model is extended to simulate heavy-ion reactions such as 6Li + 209Bi involving the weakly-bound projectile considered as a weakly-bound cluster of deuteron and 4He nuclei, thus, simulating a 3-body system in 3S-CMD model. All the essential features of breakup reactions, such as complete fusion, incomplete fusion ...

  7. Blocking of diffusion transitions of metal atoms at excitation of weakly attenuating plasmons

    CERN Document Server

    Gorelov, B M; Ogenko, V M; Shalyapina, G M

    2001-01-01

    One studies blocking transitions of metal atoms in YBa sub 2 Cu sub 3 O sub 7 high-temperature superconductor at excitation of weakly attenuating acoustic plasmons and at thermodesorption of 01 atoms. Ni and Au atoms were as diffusates. YBa sub 2 Cu sub 3 O sub 7 sub - subdelta specimens were irradiated by 9.4 GHz frequency and 10 sup 4 W power pulsed UHF-field. Temperature dependences of diffusion coefficient of Ni and Au atoms prior and subsequent to UHF irradiation and thermodesorption of 0 atoms are analyzed. It is pointed out that subsequent to UHF irradiation resistance of a specimen increases near transition into superconducting state. One makes a conclusion that blocking of space and surface transitions of Ni and Au atoms results from accumulation a large number of interstitial atoms in the surface layer of crystallites

  8. Root-flipped multiband refocusing pulses.

    Science.gov (United States)

    Sharma, Anuj; Lustig, Michael; Grissom, William A

    2016-01-01

    To design low peak power multiband refocusing radiofrequency pulses, with application to simultaneous multislice spin echo MRI. Multiband Shinnar-Le Roux β polynomials were designed using convex optimization. A Monte Carlo algorithm was used to determine patterns of β polynomial root flips that minimized the peak power of the resulting refocusing pulses. Phase-matched multiband excitation pulses were also designed to obtain linear-phase spin echoes. Simulations compared the performance of the root-flipped pulses with time-shifted and phase-optimized pulses. Phantom and in vivo experiments at 7T validated the function of the root-flipped pulses and compared them to time-shifted spin echo signal profiles. Averaged across number of slices, time-bandwidth product, and slice separation, the root-flipped pulses have 46% shorter durations than time-shifted pulses with the same peak radiofrequency amplitude. Unlike time-shifted and phase-optimized pulses, the root-flipped pulses' excitation errors do not increase with decreasing band separation. Experiments showed that the root-flipped pulses excited the desired slices at the target locations, and that for equivalent slice characteristics, the shorter root-flipped pulses allowed shorter echo times, resulting in higher signal than time-shifted pulses. The proposed root-flipped multiband radiofrequency pulse design method produces low peak power pulses for simultaneous multislice spin echo MRI. © 2015 Wiley Periodicals, Inc.

  9. Isotropy of Angular Frequencies and Weak Chimeras with Broken Symmetry

    Science.gov (United States)

    Bick, Christian

    2017-04-01

    The notion of a weak chimeras provides a tractable definition for chimera states in networks of finitely many phase oscillators. Here, we generalize the definition of a weak chimera to a more general class of equivariant dynamical systems by characterizing solutions in terms of the isotropy of their angular frequency vector—for coupled phase oscillators the angular frequency vector is given by the average of the vector field along a trajectory. Symmetries of solutions automatically imply angular frequency synchronization. We show that the presence of such symmetries is not necessary by giving a result for the existence of weak chimeras without instantaneous or setwise symmetries for coupled phase oscillators. Moreover, we construct a coupling function that gives rise to chaotic weak chimeras without symmetry in weakly coupled populations of phase oscillators with generalized coupling.

  10. Microwave-assisted Weak Acid Hydrolysis of Proteins

    Directory of Open Access Journals (Sweden)

    Miyeong Seo

    2012-06-01

    Full Text Available Myoglobin was hydrolyzed by microwave-assisted weak acid hydrolysis with 2% formic acid at 37 oC, 50 oC, and100 oC for 1 h. The most effective hydrolysis was observed at 100 oC. Hydrolysis products were investigated using matrixassistedlaser desorption/ionization time-of-flight mass spectrometry. Most cleavages predominantly occurred at the C-termini ofaspartyl residues. For comparison, weak acid hydrolysis was also performed in boiling water for 20, 40, 60, and 120 min. A 60-min weak acid hydrolysis in boiling water yielded similar results as a 60-min microwave-assisted weak acid hydrolysis at100 oC. These results strongly suggest that microwave irradiation has no notable enhancement effect on acid hydrolysis of proteinsand that temperature is the major factor that determines the effectiveness of weak acid hydrolysis.

  11. Pulse oximetry in pediatric practice.

    Science.gov (United States)

    Fouzas, Sotirios; Priftis, Kostas N; Anthracopoulos, Michael B

    2011-10-01

    The introduction of pulse oximetry in clinical practice has allowed for simple, noninvasive, and reasonably accurate estimation of arterial oxygen saturation. Pulse oximetry is routinely used in the emergency department, the pediatric ward, and in pediatric intensive and perioperative care. However, clinically relevant principles and inherent limitations of the method are not always well understood by health care professionals caring for children. The calculation of the percentage of arterial oxyhemoglobin is based on the distinct characteristics of light absorption in the red and infrared spectra by oxygenated versus deoxygenated hemoglobin and takes advantage of the variation in light absorption caused by the pulsatility of arterial blood. Computation of oxygen saturation is achieved with the use of calibration algorithms. Safe use of pulse oximetry requires knowledge of its limitations, which include motion artifacts, poor perfusion at the site of measurement, irregular rhythms, ambient light or electromagnetic interference, skin pigmentation, nail polish, calibration assumptions, probe positioning, time lag in detecting hypoxic events, venous pulsation, intravenous dyes, and presence of abnormal hemoglobin molecules. In this review we describe the physiologic principles and limitations of pulse oximetry, discuss normal values, and highlight its importance in common pediatric diseases, in which the principle mechanism of hypoxemia is ventilation/perfusion mismatch (eg, asthma exacerbation, acute bronchiolitis, pneumonia) versus hypoventilation (eg, laryngotracheitis, vocal cord dysfunction, foreign-body aspiration in the larynx or trachea). Additional technologic advancements in pulse oximetry and its incorporation into evidence-based clinical algorithms will improve the efficiency of the method in daily pediatric practice.

  12. Weakness acquired in the intensive care unit. Incidence, risk factors and their association with inspiratory weakness. Observational cohort study.

    Science.gov (United States)

    Ballve, Ladislao Pablo Diaz; Dargains, Nahuel; Inchaustegui, José García Urrutia; Bratos, Antonella; Percaz, Maria de Los Milagros; Ardariz, Cesar Bueno; Cagide, Sabrina; Balestrieri, Carolina; Gamarra, Claudio; Paz, Dario; Rotela, Eliana; Muller, Sebastian; Bustos, Fernando; Castro, Ricard Aranda; Settembrino, Esteban

    2017-12-07

    This paper sought to determine the accumulated incidence and analyze the risk factors associated with the development of weakness acquired in the intensive care unit and its relationship to inspiratory weakness. We conducted a prospective cohort study at a single center, multipurpose medical-surgical intensive care unit. We included adult patients who required mechanical ventilation ≥ 24 hours between July 2014 and January 2016. No interventions were performed. Demographic data, clinical diagnoses, the factors related to the development of intensive care unit -acquired weakness, and maximal inspiratory pressure were recorded. Of the 111 patients included, 66 developed intensive care unit -acquired weakness, with a cumulative incidence of 40.5% over 18 months. The group with intensive care unit-acquired weakness were older (55.9 ± 17.6 versus 45.8 ± 16.7), required more mechanical ventilation (7 [4 - 10] days versus 4 [2 - 7.3] days), and spent more time in the intensive care unit (15.5 [9.2 - 22.8] days versus 9 [6 - 14] days). More patients presented with delirium (68% versus 39%), hyperglycemia > 3 days (84% versus 59%), and positive balance > 3 days (73.3% versus 37%). All comparisons were significant at p 5 days as independent predictors of intensive care unit-acquired weakness. Low maximal inspiratory pressure was associated with intensive care unit-acquired weakness (p intensive care unit-acquired weakness. The intensive care unit acquired weakness is a condition with a high incidence in our environment. The development of intensive care unit-acquired weakness was associated with age, delirium, hyperglycemia, and mechanical ventilation > 5 days. The maximum inspiratory pressure value of ≥ 36cmH2O was associated with a high diagnostic value to exclude the presence of intensive care unit -acquired weakness.

  13. Measurement of the Thermal Diffusivity of GaAs by Pulsed Photothermal Spectroscopy

    Science.gov (United States)

    Bennis, G. L.; Vyas, Reeta; Gupta, R.; Ang, S.; Brown, W. D.

    1997-03-01

    Pulsed photothermal spectroscopy has been used to measure thermal diffusivity of GaAs. In this technique, a short pulse of radiation from a Ti-Sapphire laser is used to produce local heating on a sample of GaAs wafer. The heating of the sample is monitored by deflection of a weak cw laser beam (probe beam). The thermal diffusivity of the sample is deduced from the time evolution of the deflection of the probe beam. Results of the latest measurements will be presented.

  14. Selective bond breakage within the HOD molecule using optimized femtosecond ultraviolet laser pulses

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Møller, Klaus Braagaard; Henriksen, Niels Engholm

    2008-01-01

    With the HOD molecule initially in its vibrational ground state, we theoretically analyze the laser-induced control of the OD/OH branching ratio D+OH H+OD in the first absorption band. In the weak-field limit, any form of UV-pulse shaping control leads to a branching ratio larger than similar to 2....... We obtain in the strong-field limit (peak intensities similar to 10 TW/cm(2)) a branching ratio significantly less than 2. The optimized pulses operate by a pump-dump-pump mechanism, where the dumping to the electronic ground state creates nonstationary vibrational states in HOD....

  15. Coherent hard x-rays from attosecond pulse train-assisted harmonic generation

    OpenAIRE

    Klaiber, Michael; Hatsagortsyan, Karen Z.; Müller, Carsten; Keitel, Christoph H.

    2007-01-01

    High-order harmonic generation from atomic systems is considered in the crossed fields of a relativistically strong infrared laser and a weak attosecond-pulse train of soft x-rays. Due to one-photon ionization by the x-ray pulse, the ionized electron obtains a starting momentum that compensates the relativistic drift which is induced by the laser magnetic field, and allows the electron to efficiently emit harmonic radiation upon recombination with the atomic core in the relativistic regime. I...

  16. Spectral broadening of picosecond pulses forming dispersive shock waves in optical fibers.

    Science.gov (United States)

    Parriaux, A; Conforti, M; Bendahmane, A; Fatome, J; Finot, C; Trillo, S; Picqué, N; Millot, G

    2017-08-01

    We investigate analytically, numerically, and experimentally the spectral broadening of pulses that undergo the formation of dispersive shocks, addressing in particular pulses in the range of tens of ps generated via electro-optic modulation of a continuous-wave laser. We give an analytical estimate of the maximal spectral extension and show that super-Gaussian waveforms favor the generation of flat-topped spectra. We also show that the weak residual background of the modulator produces undesired spectral ripples. Spectral measurements confirm our estimates and agree well with numerical integration of the nonlinear Schrödinger equation.

  17. Radial flow pulse jet mixer

    Science.gov (United States)

    VanOsdol, John G.

    2013-06-25

    The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing vessel is comprised of a sludge basin, a flow surface surrounding the sludge basin, and a downcoming flow annulus between the flow surface and an inner shroud. The pulse jet mixing vessel is additionally comprised of an upper vessel pressurization volume in fluid communication with the downcoming flow annulus, and an inner shroud surge volume separated from the downcoming flow annulus by the inner shroud. When the solid particles are resting on the sludge basin and a fluid such as water is atop the particles and extending into the downcoming flow annulus and the inner shroud surge volume, mixing occurs by pressurization of the upper vessel pressurization volume, generating an inward radial flow over the flow surface and an upwash jet at the center of the sludge basin.

  18. Dynamics of energy coupling and thermalization in barrier discharges over dielectric and weakly conducting surfaces on µs to ms time scales

    Science.gov (United States)

    Leonov, Sergey B.; Petrishchev, Vitaly; Adamovich, Igor V.

    2014-11-01

    The paper presents experiments characterizing discharge development and energy coupling in a surface dielectric barrier discharge (SDBD), atmospheric air plasmas over dielectric and weakly conducting surfaces, over a wide range of time scales and electrical conductivities. The experiments are done using nanosecond pulse (NS) both single polarity and alternating polarity) and ac voltage waveforms. Discharge development and mechanisms of coupling with quiescent air are analysed using nanosecond gate camera imaging, schlieren imaging, and laser differential interferometry. It is shown that NS SDBD plasmas generate stochastic, localized, near-surface perturbations on a long time scale (>100 μs) after the discharge pulse. These perturbations, entirely different from compression waves generated on a short time scale (~1-10 μs), are caused by discharge contraction and originate from the ends of the filaments. Surface conductivity has almost no effect on discharge behaviour if RC time of the conducting surface layer is much longer compared to the characteristic time of NS or ac voltage waveforms. In the opposite limit of short RC time, the conducting layer acts as an extension of the high-voltage electrode. Discharge contraction significantly increases energy stored on the dielectric surface, which in this case exceeds energy dissipated as Joule heat. The stored energy is dissipated if the discharge pulse is followed by an opposite polarity pulse. In a single polarity discharge, on the other hand, surface charge accumulation limits energy coupled to the plasma by subsequent pulses. The results demonstrate that surface plasma actuator control authority may be significantly increased by using an alternating polarity pulse waveform, which is more effective than the removal of surface charge between the pulses using a weakly conducting surface.

  19. Producing High Intense Attosecond Pulse Train by Interaction of Three-Color Pulse and Overdense Plasma

    Science.gov (United States)

    Salehi, M.; Mirzanejad, S.

    2017-05-01

    Amplifying the attosecond pulse by the chirp pulse amplification method is impossible. Furthermore, the intensity of attosecond pulse is low in the interaction of laser pulse and underdense plasma. This motivates us to propose using a multi-color pulse to produce the high intense attosecond pulse. In the present study, the relativistic interaction of a three-color linearly-polarized laser-pulse with highly overdense plasma is studied. We show that the combination of {{ω }}1, {{ω }}2 and {{ω }}3 frequencies decreases the instance full width at half maximum reflected attosecond pulse train from the overdense plasma surface. Moreover, we show that the three-color pulse increases the intensity of generated harmonics, which is explained by the relativistic oscillating mirror model. The obtained results demonstrate that if the three-color laser pulse interacts with overdense plasma, it will enhance two orders of magnitude of intensity of ultra short attosecond pulses in comparison with monochromatic pulse.

  20. High power ultrashort pulse lasers

    Energy Technology Data Exchange (ETDEWEB)

    Perry, M.D.

    1994-10-07

    Small scale terawatt and soon even petawatt (1000 terawatt) class laser systems are made possible by application of the chirped-pulse amplification technique to solid-state lasers combined with the availability of broad bandwidth materials. These lasers make possible a new class of high gradient accelerators based on the large electric fields associated with intense laser-plasma interactions or from the intense laser field directly. Here, we concentrate on the laser technology to produce these intense pulses. Application of the smallest of these systems to the production of high brightness electron sources is also introduced.

  1. Pulse compressor with aberration correction

    Energy Technology Data Exchange (ETDEWEB)

    Mankos, Marian [Electron Optica, Inc., Palo Alto, CA (United States)

    2015-11-30

    In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded

  2. High-speed pulse techniques

    CERN Document Server

    Coekin, J A

    1975-01-01

    High-Speed Pulse Techniques covers the many aspects of technique in digital electronics and encompass some of the more fundamental factors that apply to all digital systems. The book describes the nature of pulse signals and their deliberate or inadvertent processing in networks, transmission lines and transformers, and then examines the characteristics and transient performance of semiconductor devices and integrated circuits. Some of the problems associated with the assembly of these into viable systems operating at ultra high speed are also looked at. The book examines the transients and w

  3. The telegraph equation for cosmic-ray transport with weak adiabatic focusing

    Science.gov (United States)

    Litvinenko, Y. E.; Schlickeiser, R.

    2013-06-01

    Time-dependent solutions of a spatial diffusion equation are often used to describe the transport of solar energetic particles, accelerated in large solar flares. Approximate analytical solutions of the diffusion approximation can complement and guide detailed numerical solutions of the Fokker-Planck equation for the particle distribution function. The accuracy of the diffusion approximation is limited, however, because the signal propagation speed is infinite in the diffusion limit. An improved description of cosmic-ray transport is provided by the telegraph equation, characterised by a finite signal propagation speed. We derive the telegraph equation for the particle density, taking into account adiabatic focusing in a large-scale interplanetary magnetic field in a weak focusing limit. As an illustration, we calculate a propagating pulse solution of the telegraph equation, determine the rise time when the maximum particle intensity is reached at a given distance from the Sun, and compare the results with those obtained in the diffusion approximation. In comparison with the diffusion equation, the telegraph equation predicts an asymmetrical shape of the pulse and a shorter rise time. These potentially significant differences suggest that the more accurate telegraph equation should be used in analysis of the solar energetic particle data, at least to quantify the accuracy of the focused diffusion model. Appendix A is available in electronic form at http://www.aanda.org

  4. Intensive care unit-acquired weakness in the burn population.

    Science.gov (United States)

    Cubitt, Jonathan J; Davies, Menna; Lye, George; Evans, Janine; Combellack, Tom; Dickson, William; Nguyen, Dai Q

    2016-05-01

    Intensive care unit-acquired weakness is an evolving problem in the burn population. As patients are surviving injuries that previously would have been fatal, the focus of treatment is shifting from survival to long-term outcome. The rehabilitation of burn patients can be challenging; however, a certain subgroup of patients have worse outcomes than others. These patients may suffer from intensive care unit-acquired weakness, and their treatment, physiotherapy and expectations need to be adjusted accordingly. This study investigates the condition of intensive care unit-acquired weakness in our burn centre. We conducted a retrospective analysis of all the admissions to our burn centre between 2008 and 2012 and identified 22 patients who suffered from intensive care unit-acquired weakness. These patients were significantly younger with significantly larger burns than those without intensive care unit-acquired weakness. The known risk factors for intensive care unit-acquired weakness are commonplace in the burn population. The recovery of these patients is significantly affected by their weakness. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  5. Weak-value Metrology and Shot-Noise Limited Measurements

    Science.gov (United States)

    Viza, Gerardo Ivan

    This thesis contains a subset of the research in which I have participated in during my studies at the University of Rochester. It contains three projects and one overarching theme of weak-value metrology. We start with chapter 1 where we cover the historical background leading up to quantum optics, which we use for precision metrology. We also introduce the weak-value formulation and give examples of metrological implementations for parameter estimation. Chapter 2 introduces two experiments to measure a longitudinal velocity and a transverse momentum kick. We show that weak-value based techniques are shot-noise limited because we saturate the Cramer-Rao bound for the estimator used, and efficient because we experimentally demonstrate there is virtually no loss of Fisher information of the parameter of interest from the discarded events. In Chapter 3 we present a comparison of two experiments that measure a beam deflection. One experiment is a weak-value based technique, while the other is the standard focusing technique. We set up the two experiments in the presence of simulated technical noise sources and show how the weak-value based technique out performs the standard technique in both visibility and in deviation of the transverse momentum kick. Chapter 4 contains work of the exploration of concatenated postselection for weak-value amplification. We demonstrate an optimization and conditions where postselecting on two degrees of freedom can be beneficial to enhance the weak-value amplification.

  6. Weaknesses, strengths and needs in fertility care according to patients.

    Science.gov (United States)

    van Empel, Inge W H; Nelen, Willianne L D M; Tepe, Eveline T; van Laarhoven, Esther A P; Verhaak, Christianne M; Kremer, Jan A M

    2010-01-01

    The patients' role in assessing health care quality is increasingly recognized. Measuring patients' specific experiences and needs generates concrete information for care improvement, whereas satisfaction surveys only give an overoptimistic, undifferentiating picture. Therefore, this study aimed to investigate possible weaknesses, strengths and needs in fertility care by measuring patients' specific experiences. Mixed (qualitative and quantitative) methods were used to identify weaknesses, strengths and needs in fertility care. Four focus groups with 21 infertile patients were used for documenting care aspects relevant to patients. The fully transcribed qualitative results were analysed and converted into a 124-item questionnaire, to investigate whether these aspects were regarded as weaknesses, strengths or needs in fertility care. The questionnaire was distributed to 369 eligible couples attending 13 Dutch fertility clinics. Descriptive statistics were used to determine the quantity of the weaknesses, strengths and needs. Overall, 286 women (78%) and 280 men (76%) completed the questionnaire. Patients experienced many weaknesses in fertility care, mostly regarding emotional support and continuity of care. Respect and autonomy and partner involvement were considered strengths in current care. Furthermore, women expressed their need for more doctors' continuity during their treatment, and couples strongly desired to have free access to their own medical record. The questionnaire's internal consistency and construct validity were sufficient. Infertile couples experience strengths, but also many weaknesses and needs in current fertility care. Lack of patient centredness seems to be a major cause herein. Using mixed methods is a sensitive means for identifying these weaknesses and needs.

  7. Lifting a weak Poisson bracket to the algebra of forms

    Science.gov (United States)

    Lyakhovich, S.; Peddie, M.; Sharapov, A.

    2017-06-01

    We detail the construction of a weak Poisson bracket over a submanifold Σ of a smooth manifold M with respect to a local foliation of this submanifold. Such a bracket satisfies a weak type Jacobi identity but may be viewed as a usual Poisson bracket on the space of leaves of the foliation. We then lift this weak Poisson bracket to a weak odd Poisson bracket on the odd tangent bundle ΠTM, interpreted as a weak Koszul bracket on differential forms on M. This lift is achieved by encoding the weak Poisson structure into a homotopy Poisson structure on an extended manifold, and lifting the Hamiltonian function that generates this structure. Such a construction has direct physical interpretation. For a generic gauge system, the submanifold Σ may be viewed as a stationary surface or a constraint surface, with the foliation given by the foliation of the gauge orbits. Through this interpretation, the lift of the weak Poisson structure is simply a lift of the action generating the corresponding BRST operator of the system.

  8. 35 Volt, 180 Ampere Pulse Generator with Droop Control for Pulsing Xenon Arcs

    DEFF Research Database (Denmark)

    Hviid, T.; Nielsen, S. O.

    1972-01-01

    The pulse generator described works as a combined switch and series current regulator and allows the shape of the current pulse to be adjusted at each optical wavelength to produce a flat pulse of monochromatic light.......The pulse generator described works as a combined switch and series current regulator and allows the shape of the current pulse to be adjusted at each optical wavelength to produce a flat pulse of monochromatic light....

  9. Dynamic Characterization of Fiber Optical Chirped Pulse Amplification for Sub-ps Pulses

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Rishøj, Lars Søgaard

    2013-01-01

    We investigate experimentally the propagation of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers, showing a significant broadening of the pulses from 450 fs up to 720 fs due to dispersion and self-phase modulation.......We investigate experimentally the propagation of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers, showing a significant broadening of the pulses from 450 fs up to 720 fs due to dispersion and self-phase modulation....

  10. Prevalence of Weak D Antigen In Western Indian Population

    Directory of Open Access Journals (Sweden)

    Tanvi Sadaria

    2015-12-01

    Full Text Available Introduction: Discovery of Rh antigens in 1939 by Landsteiner and Weiner was the revolutionary stage in blood banking. Of these antigens, D, which decides Rh positivity or negativity, is the most antigenic. A problem is encountered when an individual has a weakened expression of D (Du, i.e., fewer numbers of D antigens on red cell membrane. Aims and Objectives: To know the prevalence of weak D in Indian population because incidence varies in different population. To determine the risk of alloimmunization among Rh D negative patients who receives the blood of weak D positive donors. Material and Methods: Rh grouping of 38,962 donors who came to The Department of Immunohematology and Blood Transfusion of Civil Hospital, Ahmedabad from 1st January 2013 to 30th September 2014 was done using the DIAGAST (Automated Grouping. The samples that tested negative for D antigen were further analysed for weak D (Du by indirect antiglobulin test using blend of Ig G and Ig M Anti D. This was done using Column agglutination method in ID card (gel card. Results: The total number of donors studied was 38,962. Out of these 3360(8.6% were tested Rh D negative. All Rh D negative donors were tested for weak D (Du. 22 (0.056% of total donors and 0.65% of Rh negative donors turned out to be weak D (Du positive. Conclusion: The prevalence of weak D (Du in Western Indian population is 0.056 %, So the risk of alloimmunization in our setting due to weak D (Du antigen is marginal. But, testing of weak D antigen is necessary in blood bank because weak D antigen is immunogenic and can produce alloimmunization if transfused to Rh D negative subjects.

  11. High-Temperature-Superconducting Weak Link Defined by the Ferroelectric Field Effect

    Science.gov (United States)

    Bégon-Lours, L.; Rouco, V.; Sander, A.; Trastoy, J.; Bernard, R.; Jacquet, E.; Bouzehouane, K.; Fusil, S.; Garcia, V.; Barthélémy, A.; Bibes, M.; Santamaría, J.; Villegas, J. E.

    2017-06-01

    In all-oxide ferroelectric (F E ) superconductors (S ), due to the low carrier concentration of oxides compared to transition metals, the F E interfacial polarization charges induce an accumulation (or depletion) of charge carriers in the S . This effect leads either to an enhancement or a depression of its critical temperature, depending on the F E polarization direction. Here, we exploit this effect at a local scale to define planar weak links in high-temperature-superconducting wires. These experiments are realized in BiFeO3 (F E ) /YBa2Cu3O7 -x (S ) bilayers in which the remnant F E domain structure is "written" by locally applying voltage pulses with a conductive-tip atomic force microscope. In this fashion, the F E domain pattern defines a spatial modulation of superconductivity. This characteristic allows us to "write" a device whose electrical transport shows different temperature regimes and magnetic-field-matching effects that are characteristic of Josephson coupled weak links. This behavior illustrates the potential of the ferroelectric approach for the realization of high-temperature-superconducting devices.

  12. Earthquake Triggering by High Power Electric Pulses

    Science.gov (United States)

    Novikov, Victor; Konev, Yuri; Zeigarnik, Vladimir

    2010-05-01

    The study carried out by the Joint Institute for High Temperatures in cooperation with the Institute of Physics of the Earth and the Research Station in Bishkek of Russian Academy of Sciences in 1999-2008 showed a response of weak seismicity at field experiments with electric pulsed power systems, as well as acoustic emission of rock specimens under laboratory conditions on high-power electric current pulses applied to the rocks. It was suggested that the phenomenon discovered may be used in practice for partial release of tectonic stresses in the Earth crust for earthquake hazard mitigation. Nevertheless, the mechanism of the influence of man-made electromagnetic field on the regional seismicity is not clear yet. One of possible cause of the phenomenon may be pore fluid pressure increase in the rocks under stressed conditions due to Joule heat generation by electric current injected into the Earth crust. It is known that increase of pore fluid pressure in the fault zone over a critical pressure of about 0.05 MPa is sufficient to trigger an earthquake if the fault is near the critical state due to accumulated tectonic deformations. Detailed 3D-calculaton of electric current density in the Earth crust of the Northern Tien Shan provided by pulsed electric high-power system connected to grounded electric dipole showed that at the depth of earthquake epicenters (over 5 km) the electric current density is lower than 10-7 A/m2 that is not sufficient for increase of pressure in the fluid-saturated porous geological medium due to Joule heat generation, which may provide formation of cracks resulting in the fault propagation and release of tectonic stresses in the Earth crust. Nevertheless, under certain conditions, when electric current will be injected into the fault through the casing pipes of two deep wells with preliminary injection of conductive fluid into the fault, the current density may be high enough for significant increase of mechanic pressure in the porous two

  13. Detection of weak frequency jumps for GNSS onboard clocks.

    Science.gov (United States)

    Huang, Xinming; Gong, Hang; Ou, Gang

    2014-05-01

    In this paper, a weak frequency jump detection method is developed for onboard clocks in global navigation satellite systems (GNSS). A Kalman filter is employed to facilitate the onboard real-time processing of atomic clock measurements, whose N-step prediction residuals are used to construct the weak frequency jump detector. Numerical simulations show that the method can successfully detect weak frequency jumps. The detection method proposed in this paper is helpful for autonomous integrity monitoring of GNSS satellite clocks, and can also be applied to other frequency anomalies with an appropriately modified detector.

  14. Ultra-weak sector, Higgs boson mass, and the dilaton

    Directory of Open Access Journals (Sweden)

    Kyle Allison

    2014-11-01

    Full Text Available The Higgs boson mass may arise from a portal coupling to a singlet field σ which has a very large VEV f≫mHiggs. This requires a sector of “ultra-weak” couplings ζi, where ζi≲mHiggs2/f2. Ultra-weak couplings are technically naturally small due to a custodial shift symmetry of σ in the ζi→0 limit. The singlet field σ has properties similar to a pseudo-dilaton. We engineer explicit breaking of scale invariance in the ultra-weak sector via a Coleman–Weinberg potential, which requires hierarchies amongst the ultra-weak couplings.

  15. Linear optics implementation of weak values in Hardy's paradox

    Science.gov (United States)

    Ahnert, S. E.; Payne, M. C.

    2004-10-01

    We propose an experimental setup for the implementation of weak measurements in the context of the gedanken experiment known as Hardy’s paradox. As Aharonov et al. [Y. Aharonov, A. Botero, S. Popescu, B. Reznik, and J. Tollaksen, Phys. Lett. A301, 130 (2002)] showed, these weak values form a language with which the paradox can be resolved. Our analysis shows that this language is indeed consistent and experimentally testable. It also reveals exactly how a combination of weak values can give rise to an apparently paradoxical result.

  16. Femtosecond pulse shaping using the geometric phase.

    Science.gov (United States)

    Gökce, Bilal; Li, Yanming; Escuti, Michael J; Gundogdu, Kenan

    2014-03-15

    We demonstrate a femtosecond pulse shaper that utilizes polarization gratings to manipulate the geometric phase of an optical pulse. This unique approach enables circular polarization-dependent shaping of femtosecond pulses. As a result, it is possible to create coherent pulse pairs with orthogonal polarizations in a 4f pulse shaper setup, something until now that, to our knowledge, was only achieved via much more complex configurations. This approach could be used to greatly simplify and enhance the functionality of multidimensional spectroscopy and coherent control experiments, in which multiple coherent pulses are used to manipulate quantum states in materials of interest.

  17. Pulse image recognition using fuzzy neural network.

    Science.gov (United States)

    Xu, L S; Meng, Max Q -H; Wang, K Q

    2007-01-01

    The automatic recognition of pulse images is the key in the research of computerized pulse diagnosis. In order to automatically differentiate the pulse patterns by using small samples, a fuzzy neural network to classify pulse images based on the knowledge of experts in traditional Chinese pulse diagnosis was designed. The designed classifier can make hard decision and soft decision for identifying 18 patterns of pulse images at the accuracy of 91%, which is better than the results that achieved by back-propagation neural network.

  18. Saturation Recovery Myocardial T1 Mapping with a Composite Radiofrequency Pulse on a 3T MR Imaging System.

    Science.gov (United States)

    Morita, Kosuke; Oda, Seitaro; Utsunomiya, Daisuke; Nakaura, Takeshi; Matsubara, Takatoshi; Goto, Makoto; Okuaki, Tomoyuki; Yuki, Hideaki; Nagayama, Yasunori; Kidoh, Masafumi; Hirata, Kenichiro; Iyama, Yuij; Taguchi, Narumi; Hatemura, Masahiro; Hashida, Masahiro; Yamashita, Yasuyuki

    2017-05-18

    To evaluate the effect of a composite radiofrequency (RF) pulse on saturation recovery (SR) myocardial T1 mapping using a 3T magnetic resonance (MR) system. Phantom and in vivo studies were performed with a clinical 3T MR scanner. Accuracy and reproducibility of the SR T1 mapping using conventional and composite RF pulses were first compared in phantom experiments. An in vivo study was performed of 10 healthy volunteers who were imaged with conventional and composite RF pulse methods twice each. In vivo reproducibility of myocardial T1 value and the inter-segment variability were assessed. The phantom study revealed significant differences in the mean T1 values between the two methods, and the reproducibility for the composite RF pulse was significantly smaller than that for the conventional RF pulse. For both methods, the correlations of the reference and measured T1 values were excellent (r(2) = 0.97 and 0.98 for conventional and composite RF pulses, respectively). The in vivo study showed that the mean T1 value for composite RF pulse was slightly lower than that for conventional RF pulse, but this difference was not significant (P = 0.06). The inter-segment variability for the composite RF pulse was significantly smaller than that for conventional RF pulse (P T1 measurements of the first and second scans were highly and weakly correlated to composite RF pulses (r = 0.83 and 0.29, respectively). SR T1 mapping using composite RF pulse provides accurate quantification of T1 values and can lessen measurement variability and enable reproducible T1 measurements.

  19. Wave equations for pulse propagation

    Science.gov (United States)

    Shore, B. W.

    1987-06-01

    Theoretical discussions of the propagation of pulses of laser radiation through atomic or molecular vapor rely on a number of traditional approximations for idealizing the radiation and the molecules, and for quantifying their mutual interaction by various equations of propagation (for the radiation) and excitation (for the molecules). In treating short-pulse phenomena it is essential to consider coherent excitation phenomena of the sort that is manifest in Rabi oscillations of atomic or molecular populations. Such processes are not adequately treated by rate equations for excitation nor by rate equations for radiation. As part of a more comprehensive treatment of the coupled equations that describe propagation of short pulses, this memo presents background discussion of the equations that describe the field. This memo discusses the origin, in Maxwell's equations, of the wave equation used in the description of pulse propagation. It notes the separation into lamellar and solenoidal (or longitudinal and transverse) and positive and negative frequency parts. It mentions the possibility of separating the polarization field into linear and nonlinear parts, in order to define a susceptibility or index of refraction and, from these, a phase and group velocity.

  20. Anaesthetic Monitoring - the Pulse Oximeter

    African Journals Online (AJOL)

    the pulse oximeter: 1. It is a teaching tool showing the physiology of oxygen delivery. 2. It is especially useful to evaluate the efficacy of oxygen therapy during recovery from an- aesthesia and surgery and on the ward. 3. It shows when tracheal intubation is too slow. It shows when the tube is in the wrong place or blocked or ...

  1. Nonparametric estimation of ultrasound pulses

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Leeman, Sidney

    1994-01-01

    An algorithm for nonparametric estimation of 1D ultrasound pulses in echo sequences from human tissues is derived. The technique is a variation of the homomorphic filtering technique using the real cepstrum, and the underlying basis of the method is explained. The algorithm exploits a priori...

  2. Atomic collisions involving pulsed positrons

    DEFF Research Database (Denmark)

    Merrison, J. P.; Bluhme, H.; Field, D.

    2000-01-01

    instantaneous intensities be achieved with in-beam accumulation, but more importantly many orders of magnitude improvement in energy and spatial resolution can be achieved using positron cooling. Atomic collisions can be studied on a new energy scale with unprecedented precion and control. The use...... of accelerators for producing intense positron pulses will be discussed in the context of atomic physics experiments....

  3. Pulses and waves of contractility.

    Science.gov (United States)

    Wu, Min

    2017-12-04

    The nature of signal transduction networks in the regulation of cell contractility is not entirely clear. In this study, Graessl et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201706052) visualized and characterized pulses and waves of Rho activation in adherent cells and proposed excitable Rho signaling networks underlying cell contractility. © 2017 Wu.

  4. Existence of Weak Solutions for a Nonlinear Elliptic System

    Directory of Open Access Journals (Sweden)

    Gilbert RobertP

    2009-01-01

    Full Text Available We investigate the existence of weak solutions to the following Dirichlet boundary value problem, which occurs when modeling an injection molding process with a partial slip condition on the boundary. We have in ; in ; , and on .

  5. Weak measurements measure probability amplitudes (and very little else)

    Energy Technology Data Exchange (ETDEWEB)

    Sokolovski, D., E-mail: dgsokol15@gmail.com [Departmento de Química-Física, Universidad del País Vasco, UPV/EHU, Leioa (Spain); IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013, Bilbao (Spain)

    2016-04-22

    Conventional quantum mechanics describes a pre- and post-selected system in terms of virtual (Feynman) paths via which the final state can be reached. In the absence of probabilities, a weak measurement (WM) determines the probability amplitudes for the paths involved. The weak values (WV) can be identified with these amplitudes, or their linear combinations. This allows us to explain the “unusual” properties of the WV, and avoid the “paradoxes” often associated with the WM. - Highlights: • Weak measurement on a pre- and post-selected system is a particular perturbative scheme. • A conventional average for the additional degree of freedom measured. • The result is proportional to the amplitudes on the virtual paths connecting two system's states. • Over-interpretation of the weak values (WV) is unwise. • “Unusual” WVs are not unusual after all.

  6. Hysteresis in superconducting short weak links and μ -SQUIDs

    Science.gov (United States)

    Hazra, Dibyendu; Pascal, Lætitia M. A.; Courtois, Hervé; Gupta, Anjan K.

    2010-11-01

    Thermal hysteresis in a micron-size superconducting quantum interference device ( μ -SQUID), with weak links as Josephson junctions, is an obstacle for improving its performance for magnetometry. Following the “hot-spot” model of Skocpol [J. Appl. Phys. 45, 4054 (1974)]10.1063/1.1663912 and by incorporating the temperature dependence of the superconductor thermal conductivity under a linear approximation, we find a much better agreement with the observed temperature dependence of the retrapping current in short superconducting Nb-based weak links and μ -SQUIDs. In addition, using the temperature dependence of the critical current, we find that above a certain temperature hysteresis disappears. We analyze the current-voltage characteristics and the weak link temperature variation in both the hysteretic and nonhysteretic regimes. We also discuss the effect of the weak link geometry in order to widen the temperature range of hysteresis-free operation.

  7. Space group constraints on weak indices in topological insulators

    Science.gov (United States)

    Varjas, Dániel; de Juan, Fernando; Lu, Yuan-Ming

    2017-07-01

    Lattice translation symmetry gives rise to a large class of "weak" topological insulators (TIs), characterized by translation-protected gapless surface states and dislocation bound states. In this work we show that space group symmetries lead to constraints on the weak topological indices that define these phases. In particular, we show that screw rotation symmetry enforces the Hall conductivity in planes perpendicular to the screw axis to be quantized in multiples of the screw rank, which generally applies to interacting systems. We further show that certain 3D weak indices associated with quantum spin Hall effects (class AII) are forbidden by the Bravais lattice and by glide or even-fold screw symmetries. These results put strong constraints on weak TI candidates in the experimental and numerical search for topological materials, based on the crystal structure alone.

  8. A weakly compressible formulation for modelling liquid-gas sloshing

    CSIR Research Space (South Africa)

    Heyns, Johan A

    2012-09-01

    Full Text Available , the implementation of a weakly compressible formulation which accounts for variations in the gas density is presented. With the aim of ensuring a computational efficient implementation of the proposed formulation, an implicit iterative GMRES solver with LU...

  9. Ultrasmall polarization rotation measurements via weak value amplification

    Energy Technology Data Exchange (ETDEWEB)

    Lima Bernardo, Bertúlio de, E-mail: bertulio@fisica.ufpb.br; Azevedo, Sérgio; Rosas, Alexandre

    2014-06-13

    Highlights: • We present a class of weak measurements where the measurer is an angular variable of the system. • Photon-energy qubits are required, which seems to be the first application of this kind of light. • Both weak optical activity and reflection-induced polarization rotation can be amplified. • This protocol can amplify the optical activity signal in nanostructures and biological tissues. - Abstract: We propose a framework to analyze weak measurements based on an angular version of the von Neumann measurement scheme, where the coupling between the system and the meter causes rotation of the measuring variable. We also discuss an experimental application of this theory in which measurements of weak optical activity and reflection-induced polarization rotation could be amplified in nearly two orders of magnitude. It can shed a new light on a great variety of physical chemistry, molecular biology and nanotechnology studies.

  10. Strengths only or strengths and relative weaknesses? A preliminary study.

    Science.gov (United States)

    Rust, Teri; Diessner, Rhett; Reade, Lindsay

    2009-10-01

    Does working on developing character strengths and relative character weaknesses cause lower life satisfaction than working on developing character strengths only? The present study provides a preliminary answer. After 76 college students completed the Values in Action Inventory of Strengths (C. Peterson & M. E. P. Seligman, 2004), the authors randomly assigned them to work on 2 character strengths or on 1 character strength and 1 relative weakness. Combined, these groups showed significant gains on the Satisfaction With Life Scale (E. Diener, R. A. Emmons, R. J. Larsen, & S. Griffin, 1985), compared with a 32-student no-treatment group. However, there was no significant difference in gain scores between the 2-strengths group and the 1-character-strength-and-1-relative-character-weakness group. The authors discuss how focusing on relative character weaknesses (along with strengths) does not diminish-and may assist in increasing-life satisfaction.

  11. Managing Chemotherapy Side Effects: Fatigue (Feeling Weak and Very Tired)

    Science.gov (United States)

    ... ancer I nstitute Managing Chemotherapy Side Effects Fatigue (Feeling weak and very tired) Why do I feel ... level. Some people write down how they are feeling each day in a notebook to share with ...

  12. Graphene-Based Superconducting Weak Links in Low Magnetic Field

    Science.gov (United States)

    Mills, Scott; Kumaravadivel, Piranavan; Du, Xu

    The impact of magnetic field on Andreev reflection is studied in graphene-based superconducting weak links. We found, through studying weak links with different adhesion layers and superconducting leads (including Graphene-Ti/Au-Nb, Graphene-Ti/Pd-Nb, Graphene-V-Nb, Graphene-Ti-Nb, Graphene-Ti/Pd-NbN), that in low field (B graphene-superconductor interface. As the effective gap of the weak link approaches the intrinsic gap of the superconducting leads, a remnant of Andreev reflection can survive into the quantum Hall regime, allowing study of the interplay between the quantum Hall effect and Andreev reflection in high quality suspended graphene-superconductor weak links.

  13. Notification: FY 2018 CSB Management Challenges and Internal Control Weaknesses

    Science.gov (United States)

    December 26, 2017. The OIG is beginning work to update for fiscal year 2018 its list of proposed key management challenges and internal control weaknesses confronting the U.S. Chemical Safety and Hazard Investigation Board (CSB).

  14. Selective diaphragm muscle weakness after contractile inactivity during thoracic surgery.

    NARCIS (Netherlands)

    Welvaart, W.N.; Paul, M.A.; Stienen, G.J.; Hees, H.W.H. van; Loer, S.A.; Bouwman, R.; Niessen, H.; Man, F.S. de; Witt, C.C.; Granzier, H.; Vonk-Noordegraaf, A.; Ottenheijm, C.A.C.

    2011-01-01

    RATIONALE: Postoperative pulmonary complications are significant contributors to morbidity in patients who have undergone upper abdominal, thoracic, or cardiac surgery. The pathophysiology of these complications might involve postoperative inspiratory muscle weakness. The nature of postoperative

  15. Undecidability of Weak Bisimilarity for PA-Processes

    DEFF Research Database (Denmark)

    Srba, Jiri

    2003-01-01

    We prove that the problem whether two PA-processes are weakly bisimilar is undecidable. We combine several proof techniques to provide a reduction from Post's correspondence problem to our problem: existential quantification technique, masking technique and deadlock elimination technique....

  16. National Transportation Safety Board : weak internal control impaired financial accountability

    Science.gov (United States)

    2001-09-28

    The U. S. General Accounting Office (GAO) was asked to review the National Transportation Safety Board's (NTSB) internal controls over selected types of fiscal year expenditures. They were asked to determine whether internal control weaknesses were a...

  17. Informal Institutions and the "Weaknesses" of Human Behavior

    National Research Council Canada - National Science Library

    Goebel, Markus; Thomas, Tobias

    2005-01-01

    ... to interpersonal consistency and interpersonal conformity here. These sources of a systematic deviation from the standard model of the homo oeconomicus result in systematic weaknesses of perception and deviations of behavior...

  18. Electrostatics in Chemistry-Electrostatic Models for Weak Molecular ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 12. Electrostatics in Chemistry - Electrostatic Models for Weak Molecular Complexation. Shridhar R Gadre Pravin K Babu. Series Article Volume 4 Issue 12 December 1999 pp 11-20 ...

  19. Compressive strength of brick masonry made with weak mortars

    DEFF Research Database (Denmark)

    Pedersen, Erik Steen; Hansen, Klavs Feilberg

    2013-01-01

    (fm≈6 N/mm2) compression tests of masonry with perforated bricks show that the EC6 expression is not always safe for Danish masonry. This is probably because the tensile strength of the bricks also has an effect on the compressive strength of masonry when the mortar is stronger than weak lime mortar......The use of weak mortar has a number of advantages (e.g. prevention of expansion joints, environmental issues). However, according to EC6, the strength of masonry vanishes when the compressive strength of the mortar approaches zero. In reality the presence of even unhardened mortar kept in place...... in the joint will ensure a certain level of load-carrying capacity. This is due to the interaction between compression in the weak mortar and tension in the adjacent bricks. This paper proposes an expression for the compressive strength of masonry made with weak lime mortars (fmstrength...

  20. Stability in Real Food Webs: Weak Links in Long Loops

    National Research Council Canada - National Science Library

    Anje-Margriet Neutel; Johan A. P. Heesterbeek; Peter C. de Ruiter

    2002-01-01

    ... of these patterns, how they come about, and why they influence stability. We show that in real food webs, interaction strengths are organized in trophic loops in such a way that long loops contain relatively many weak links...

  1. Cryosurgery with Pulsed Electric Fields

    Science.gov (United States)

    Daniels, Charlotte S.; Rubinsky, Boris

    2011-01-01

    This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to

  2. Cryosurgery with pulsed electric fields.

    Directory of Open Access Journals (Sweden)

    Charlotte S Daniels

    Full Text Available This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused

  3. Wave equations for pulse propagation

    Energy Technology Data Exchange (ETDEWEB)

    Shore, B.W.

    1987-06-24

    Theoretical discussions of the propagation of pulses of laser radiation through atomic or molecular vapor rely on a number of traditional approximations for idealizing the radiation and the molecules, and for quantifying their mutual interaction by various equations of propagation (for the radiation) and excitation (for the molecules). In treating short-pulse phenomena it is essential to consider coherent excitation phenomena of the sort that is manifest in Rabi oscillations of atomic or molecular populations. Such processes are not adequately treated by rate equations for excitation nor by rate equations for radiation. As part of a more comprehensive treatment of the coupled equations that describe propagation of short pulses, this memo presents background discussion of the equations that describe the field. This memo discusses the origin, in Maxwell's equations, of the wave equation used in the description of pulse propagation. It notes the separation into lamellar and solenoidal (or longitudinal and transverse) and positive and negative frequency parts. It mentions the possibility of separating the polarization field into linear and nonlinear parts, in order to define a susceptibility or index of refraction and, from these, a phase and group velocity. The memo discusses various ways of characterizing the polarization characteristics of plane waves, that is, of parameterizing a transverse unit vector, such as the Jones vector, the Stokes vector, and the Poincare sphere. It discusses the connection between macroscopically defined quantities, such as the intensity or, more generally, the Stokes parameters, and microscopic field amplitudes. The material presented here is a portion of a more extensive treatment of propagation to be presented separately. The equations presented here have been described in various books and articles. They are collected here as a summary and review of theory needed when treating pulse propagation.

  4. What are the weak points of LHC operation?

    CERN Document Server

    Goddard, B

    2010-01-01

    The few weeks of LHC operation in 2009 was a resounding success with extremely fast progress in the beam commissioning. Nevertheless, the period also revealed a number of possible weaknesses in various aspects of the LHC operation, including procedures, tools, discipline, equipment and organisation. The weaknesses are discussed with a view to feeding the experience back to improve the machine operation for 2010 and beyond. The distinction is made impacting efficiency, and those points which are more serious and might impact machine protection.

  5. Experimentally quantifying the advantages of weak-value-based metrology

    OpenAIRE

    Viza, Gerardo I.; Martínez-Rincón, Julián; Alves, Gabriel B.; Jordan, Andrew N.; Howell, John C.

    2014-01-01

    We experimentally investigate the relative advantages of implementing weak-value-based metrology versus standard methods. While the techniques outlined herein apply more generally, we measure small optical beam deflections both using a Sagnac interferometer with a monitored dark port (the weak-value-based technique), and by focusing the entire beam to a split detector (the standard technique). By introducing controlled external transverse detector modulations and transverse beam deflection mo...

  6. Strength and Weakness of Animal Vaccine Industry in China

    OpenAIRE

    Xie, Hong-hai; Wang, Geng-xin

    2010-01-01

    Based on the introduction of the status of animal vaccine industry in China, the strength, weakness, opportunity and threat of animal vaccine industry is analyzed by SWOT. Among them, strength is mainly reflected in the broad market, and the favorable industrial policy and development environment. Weakness is the irrational structure of product, the nonstandard production inspection, and the irregular market. Opportunity is mainly reflected in improving government’s emphasis on animal secur...

  7. Updating the theoretical analysis of the weak gravitational shielding experiment

    CERN Document Server

    Modanese, G

    1996-01-01

    The most recent data about the weak gravitational shielding produced recently through a levitating and rotating HTC superconducting disk show a very weak dependence of the shielding value ($\\sim 1 \\%$) on the height above the disk. We show that whilst this behaviour is incompatible with an intuitive vectorial picture of the shielding, it is consistently explained by our theoretical model. The expulsive force observed at the border of the shielded zone is due to energy conservation.

  8. Classical and Weak Solutions for Two Models in Mathematical Finance

    Science.gov (United States)

    Gyulov, Tihomir B.; Valkov, Radoslav L.

    2011-12-01

    We study two mathematical models, arising in financial mathematics. These models are one-dimensional analogues of the famous Black-Scholes equation on finite interval. The main difficulty is the degeneration at the both ends of the space interval. First, classical solutions are studied. Positivity and convexity properties of the solutions are discussed. Variational formulation in weighted Sobolev spaces is introduced and existence and uniqueness of the weak solution is proved. Maximum principle for weak solution is discussed.

  9. MRT letter: recovering weak-textured surfaces using image focus.

    Science.gov (United States)

    Muhammad, Mannan Saeed; Choi, Tae-Sun

    2009-10-01

    In nature, objects have partially weak texture and their shape reconstruction using focus based passive methods like shape from focus (SFF), is difficult. This article presents a new SFF algorithm which can compute precise depth of dense as well as weak textured objects. Segmentation is applied to discard wrong depth estimate and then later interpolating them from accurate depth values of their neighbors. The performance of the proposed method is tested, using different image sequences of synthetic and real objects, with varying textures.

  10. Plasma channels during filamentation of a femtosecond laser pulse with wavefront astigmatism in air

    Energy Technology Data Exchange (ETDEWEB)

    Dergachev, A A; Kandidov, V P; Shlenov, S A [Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation); Ionin, A A; Mokrousova, D V; Seleznev, L V; Sinitsyn, D V; Sunchugasheva, E S; Shustikova, A P [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2014-12-31

    We have demonstrated experimentally and numerically the possibility of controlling parameters of plasma channels formed during filamentation of a femtosecond laser pulse by introducing astigmatism in the laser beam wavefront. It is found that weak astigmatism increases the length of the plasma channel in comparison with the case of aberration-free focusing and that strong astigmatism can cause splitting of the plasma channel into two channels located one after another on the filament axis. (interaction of laser radiation with matter. laser plasma)

  11. Localization of cold atoms in state-dependent optical lattices via a Rabi Pulse.

    Science.gov (United States)

    Horstmann, Birger; Dürr, Stephan; Roscilde, Tommaso

    2010-10-15

    We propose a novel realization of Anderson localization in nonequilibrium states of ultracold atoms in an optical lattice. A Rabi pulse transfers part of the population to a different internal state with infinite effective mass. These frozen atoms create a quantum superposition of different disorder potentials, localizing the mobile atoms. For weakly interacting mobile atoms, Anderson localization is obtained. The localization length increases with increasing disorder and decreasing interaction strength, contrary to the expectation for equilibrium localization.

  12. Weak bond detection in composites using highly nonlinear solitary waves

    Science.gov (United States)

    Singhal, Taru; Kim, Eunho; Kim, Tae-Yeon; Yang, Jinkyu

    2017-05-01

    We experimentally investigate a diagnostic technique for identifying a weak bond in composites using highly nonlinear solitary waves (HNSWs). We set up a one-dimensional chain of granular crystals, consisting of spherical particles with nonlinear interactions, to generate HNSWs. These solitary wave packets are transmitted into an inspection area of composites by making a direct contact with the chain. We demonstrate that a strong type of solitary waves injected to the weak bond area can break the weak bond of laminates, thereby causing delamination. Then, to identify the creation of the delamination, we transmit a weak type of solitary waves by employing the same apparatus, and measure the solitary waves reflected from the specimens. By analyzing these reflected solitary waves, we differentiate the weak bond samples with the pristine bond ones in an efficient and fast manner. The diagnostic results based on the proposed method are compared with the strength and energy release rate at bond interfaces, which are measured via standard testing methods such as three point bending and end notched flexure tests. This study shows the potential of solitary wave-based detection of weak bonds for hot spot monitoring of composite-based structures.

  13. Pulse propagation and optically controllable switch in coupled semiconductor-double-quantum-dot nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Hamedi, H. R., E-mail: hamid.r.hamedi@gmail.com, E-mail: hamid.hamedi@tfai.vu.lt [Institute of Theoretical Physics and Astronomy, Vilnius University Sauletekio 3 LT-10222 Vilnius (Lithuania)

    2016-05-14

    The problem of pulse propagation is theoretically investigated through a coupled semiconductor-double-quantum-dot (SDQD) nanostructure. Solving the coupled Maxwell–Bloch equations for the SDQD and field simultaneously, the dynamic control of pulse propagation through the medium is numerically explored. It is found that when all the control fields are in exact resonance with their corresponding transitions, a weak Gaussian-shaped probe pulse is transmitted through the medium nearly without any significant absorption and losses so that it can preserve its shape for quite a long propagation distance. In contrast, when one of the control fields is not in resonance with its corresponding transition, the probe pulse will be absorbed by the QD medium after a short distance. Then we consider the probe pulses with higher intensities. It is realized that an intense probe pulse experiences remarkable absorption and broadening during propagation. Finally, we demonstrate that this SDQD system can be employed as an optically controllable switch for the wave propagation to transit from an absorbing phase to a perfect transparency for the probe field. The required time for such switch is also estimated through realistic values.

  14. Pulse propagation and optically controllable switch in coupled semiconductor-double-quantum-dot nanostructures

    Science.gov (United States)

    Hamedi, H. R.

    2016-05-01

    The problem of pulse propagation is theoretically investigated through a coupled semiconductor-double-quantum-dot (SDQD) nanostructure. Solving the coupled Maxwell-Bloch equations for the SDQD and field simultaneously, the dynamic control of pulse propagation through the medium is numerically explored. It is found that when all the control fields are in exact resonance with their corresponding transitions, a weak Gaussian-shaped probe pulse is transmitted through the medium nearly without any significant absorption and losses so that it can preserve its shape for quite a long propagation distance. In contrast, when one of the control fields is not in resonance with its corresponding transition, the probe pulse will be absorbed by the QD medium after a short distance. Then we consider the probe pulses with higher intensities. It is realized that an intense probe pulse experiences remarkable absorption and broadening during propagation. Finally, we demonstrate that this SDQD system can be employed as an optically controllable switch for the wave propagation to transit from an absorbing phase to a perfect transparency for the probe field. The required time for such switch is also estimated through realistic values.

  15. Linear transformer driver for pulse generation

    Science.gov (United States)

    Kim, Alexander A; Mazarakis, Michael G; Sinebryukhov, Vadim A; Volkov, Sergey N; Kondratiev, Sergey S; Alexeenko, Vitaly M; Bayol, Frederic; Demol, Gauthier; Stygar, William A

    2015-04-07

    A linear transformer driver includes at least one ferrite ring positioned to accept a load. The linear transformer driver also includes a first power delivery module that includes a first charge storage devices and a first switch. The first power delivery module sends a first energy in the form of a first pulse to the load. The linear transformer driver also includes a second power delivery module including a second charge storage device and a second switch. The second power delivery module sends a second energy in the form of a second pulse to the load. The second pulse has a frequency that is approximately three times the frequency of the first pulse. The at least one ferrite ring is positioned to force the first pulse and the second pulse to the load by temporarily isolating the first pulse and the second pulse from an electrical ground.

  16. Coherent combining pulse bursts in time domain

    Energy Technology Data Exchange (ETDEWEB)

    Galvanauskas, Almantas

    2018-01-09

    A beam combining and pulse stacking technique is provided that enhances laser pulse energy by coherent stacking pulse bursts (i.e. non-periodic pulsed signals) in time domain. This energy enhancement is achieved by using various configurations of Fabry-Perot, Gires-Tournois and other types of resonant cavities, so that a multiple-pulse burst incident at either a single input or multiple inputs of the system produces an output with a solitary pulse, which contains the summed energy of the incident multiple pulses from all beams. This disclosure provides a substantial improvement over conventional coherent-combining methods in that it achieves very high pulse energies using a relatively small number of combined laser systems, thus providing with orders of magnitude reduction in system size, complexity, and cost compared to current combining approaches.

  17. Treatment Pulse Application for Magnetic Stimulation

    Directory of Open Access Journals (Sweden)

    Sun-Seob Choi

    2011-01-01

    Full Text Available Treatment and diagnosis can be made in difficult areas simply by changing the output pulse form of the magnetic stimulation device. However, there is a limitation in the range of treatments and diagnoses of a conventional sinusoidal stimulation treatment pulse because the intensity, width, and form of the pulse must be changed according to the lesion type. This paper reports a multidischarge method, where the stimulation coils were driven in sequence via multiple switching control. The limitation of the existing simple sinusoidal pulse form could be overcome by changing the intensity, width, and form of the pulse. In this study, a new sequential discharge method was proposed to freely alter the pulse width. The output characteristics of the stimulation treatment pulse were examined according to the trigger signal delay applied to the switch at each stage by applying a range of superposition pulses to the magnetic simulation device, which is widely used in industry and medicine.

  18. Peak holding circuit for extremely narrow pulses

    Science.gov (United States)

    Oneill, R. W. (Inventor)

    1975-01-01

    An improved pulse stretching circuit comprising: a high speed wide-band amplifier connected in a fast charge integrator configuration; a holding circuit including a capacitor connected in parallel with a discharging network which employs a resistor and an FET; and an output buffer amplifier. Input pulses of very short duration are applied to the integrator charging the capacitor to a value proportional to the input pulse amplitude. After a predetermined period of time, conventional circuitry generates a dump pulse which is applied to the gate of the FET making a low resistance path to ground which discharges the capacitor. When the dump pulse terminates, the circuit is ready to accept another pulse to be stretched. The very short input pulses are thus stretched in width so that they may be analyzed by conventional pulse height analyzers.

  19. Anterior capsulotomy with a pulsed-electron avalanche knife.

    Science.gov (United States)

    Palanker, Daniel; Nomoto, Hiroyuki; Huie, Philip; Vankov, Alexander; Chang, David F

    2010-01-01

    To evaluate a new pulsed-electron avalanche knife design for creating a continuous curvilinear capsulotomy (CCC) and compare the CCC with a mechanical capsulorhexis. Department of Ophthalmology, Stanford University, Stanford, California, USA. In this study, CCCs were created in freshly enucleated bovine eyes and in rabbit eyes in vivo. The cutting velocity was adjusted by controlling the burst repetition rate, voltage amplitude, and burst duration. Tissue samples were fixed and processed for histology and scanning electron microscopy (SEM) immediately after surgery. The study included 50 bovine eyes and 10 rabbit eyes. By adjusting the electrosurgical waveforms, gas-bubble formation was minimized to permit good surgical visualization. The optimum voltage level was determined to be +/-410 V with a burst duration of 20 mus. Burst repetition rate, continuously adjustable from 20 to 200 Hz with footpedal control, allowed the surgeon to vary linear cutting velocity up to 2.0 mm/s. Histology and SEM showed that the pulsed-electron avalanche knife produced sharp-edged capsule cutting without radial nicks or tears. The probe of the pulsed-electron avalanche knife duplicated the surgical feel of a 25-gauge cystotome and created a histologically smooth capsule cut. It may improve precision and reproducibility of creating a CCC, as well as improve its proper sizing and centration, especially in the face of surgical risk factors, such as weak zonules or poor visibility. Drs. Palanker and Vankov hold patents to the pulsed electron avalanche knife technology, which are licensed to PEAK Surgical by Stanford University. Drs. Palanker and Chang are consultants to PEAK Surgical. Dr. Vankov is an employee of PEAK Surgical. Neither of the other authors has a financial or proprietary interest in any material or method mentioned. Copyright 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  20. Pulsed lasers in speckle photography: error owing to pulse width.

    Science.gov (United States)

    Joenathan, C; Blair, S M; Ganesan, A R

    1993-01-10

    The effect of the pulse width of a pulsed laser in the studies of speckle velocimetry and transient vibration analysis is discussed. Because of the motion of the object during an exposure, a sine function is obtained by using the pointwise filtering method. This function modulates the halo along with the Young's fringes. It is shown that for high object velocities the sinc function modifies the halo distribution; as a result, the error in calculating the fringe position increases. An aperture geometry for which the autocorrelation halo is made constant in certain regions is proposed in which the intensity variation in this region is the result of the modulating sinc function only. A closed-form solution for the shift in the position of the fringes in this region is obtained. Experimental results of the simulation are presented.

  1. Sensors and Methods for Electromagnetic Pulse Identification

    OpenAIRE

    Pavel FIALA; Drexler, Petr

    2006-01-01

    There are some suitable methods for the measurement of ultra-short solitary electromagnetic pulses that can be generated by high power pulsed generators. The measurement methods properties have to correspond to the fact whether we want to measure pulses of voltage, current or free-space electromagnetic wave. The need for specific measurement methods occurred by the development of high power microwave pulse generator. Applicable methods are presented in this paper. The method utilizing Faraday...

  2. Finite pulse effects in CPMG pulse trains on paramagnetic materials.

    Science.gov (United States)

    Leskes, Michal; Grey, Clare P

    2015-09-14

    The Carr-Purcell-Meiboom-Gill (CPMG) sequence is commonly used in high resolution NMR spectroscopy and in magnetic resonance imaging for the measurement of transverse relaxation in systems that are subject to diffusion in internal or external gradients and is superior to the Hahn echo measurement, which is more sensitive to diffusion effects. Similarly, it can potentially be used to study dynamic processes in electrode materials for lithium ion batteries. Here we compare the (7)Li signal decay curves obtained with the CPMG and Hahn echo sequences under static conditions (i.e., in the absence of magic angle spinning) in paramagnetic materials with varying transition metal ion concentrations. Our results indicate that under CPMG pulse trains the lifetime of the (7)Li signal is substantially extended and is correlated with the strength of the electron-nuclear interaction. Numerical simulations and analytical calculations using Floquet theory suggest that the combination of large interactions and a train of finite pulses, results in a spin locking effect which significantly slows the signal's decay. While these effects complicate the interpretation of CPMG-based investigations of diffusion and chemical exchange in paramagnetic materials, they may provide a useful approach to extend the signal's lifetime in these often fast relaxing systems, enabling the use of correlation experiments. Furthermore, these results highlight the importance of developing a deeper understanding of the effects of the large paramagnetic interactions during multiple pulse experiments in order to extend the experimental arsenal available for static and in situ NMR investigations of paramagnetic materials.

  3. <3> OMEGA pulse-forming network

    CERN Multimedia

    1974-01-01

    Adjustement of the 3 W pulse-forming network of the SPS beam dumping system. When charged at 60 kV, this PFN gives 10 kA, 25 ms current pulses, with oscillations, superimposed on the pulse flat top, of an amplitude of +/- 1 Ka.

  4. A Study of New Pulse Auscultation System

    Directory of Open Access Journals (Sweden)

    Ying-Yun Chen

    2015-04-01

    Full Text Available This study presents a new type of pulse auscultation system, which uses a condenser microphone to measure pulse sound waves on the wrist, captures the microphone signal for filtering, amplifies the useful signal and outputs it to an oscilloscope in analog form for waveform display and storage and delivers it to a computer to perform a Fast Fourier Transform (FFT and convert the pulse sound waveform into a heartbeat frequency. Furthermore, it also uses an audio signal amplifier to deliver the pulse sound by speaker. The study observed the principles of Traditional Chinese Medicine’s pulsing techniques, where pulse signals at places called “cun”, “guan” and “chi” of the left hand were measured during lifting (100 g, searching (125 g and pressing (150 g actions. Because the system collects the vibration sound caused by the pulse, the sensor itself is not affected by the applied pressure, unlike current pulse piezoelectric sensing instruments, therefore, under any kind of pulsing pressure, it displays pulse changes and waveforms with the same accuracy. We provide an acquired pulse and waveform signal suitable for Chinese Medicine practitioners’ objective pulse diagnosis, thus providing a scientific basis for this Traditional Chinese Medicine practice. This study also presents a novel circuit design using an active filtering method. An operational amplifier with its differential features eliminates the interference from external signals, including the instant high-frequency noise. In addition, the system has the advantages of simple circuitry, cheap cost and high precision.

  5. Experiments on sediment pulses in mountain rivers

    Science.gov (United States)

    Y. Cui; T. E. Lisle; J. E. Pizzuto; G. Parker

    1998-01-01

    Pulses of sediment can be introduced into mountain rivers from such mechanisms as debris flows, landslides and fans at tributary confluences. These processes can be natural or associated with the activities of humans, as in the case of a pulse created by sediment derived from timber harvest or the removal of a dam. How does the river digest these pulses?

  6. Third Harmonic Imaging using a Pulse Inversion

    DEFF Research Database (Denmark)

    Rasmussen, Joachim; Du, Yigang; Jensen, Jørgen Arendt

    2011-01-01

    The pulse inversion (PI) technique can be utilized to separate and enhance harmonic components of a waveform for tissue harmonic imaging. While most ultrasound systems can perform pulse inversion, only few image the 3rd harmonic component. PI pulse subtraction can isolate and enhance the 3rd...

  7. High speed, high current pulsed driver circuit

    Science.gov (United States)

    Carlen, Christopher R.

    2017-03-21

    Various technologies presented herein relate to driving a LED such that the LED emits short duration pulses of light. This is accomplished by driving the LED with short duration, high amplitude current pulses. When the LED is driven by short duration, high amplitude current pulses, the LED emits light at a greater amplitude compared to when the LED is driven by continuous wave current.

  8. Double pulse Thomson scattering system at RTP

    NARCIS (Netherlands)

    Beurskens, M. N. A.; Barth, C. J.; Chu, C.C.; Donne, A. J. H.; Herranz, J. A.; Cardozo, N. J. L.; van der Meiden, H. J.; Pijper, F.J.

    1997-01-01

    In this article a double pulse multiposition Thomson scattering diagnostic, under construction at RTP, is discussed. Light from a double pulsed ruby laser (pulse separation: 10-800 mu s, max. 2x12.5 J) is scattered by the free electrons of the tokamak plasma and relayed to a Littrow polychromator

  9. Generation of air lasing at extended distances by coaxial dual-color femtosecond laser pulses

    Science.gov (United States)

    Li, Helong; Zang, Hongwei; Su, Yue; Fu, Yao; Xu, Huailiang

    2017-12-01

    We present an approach for generation of air lasing at extended distances by coaxial dual-color femtosecond laser pulses. A strong 800 nm pulse prepares the population inversion in {{{N}}}2+ during the filamentation in air, and a weak 400 nm pulse produced coaxially with the 800 nm light by frequency doubling in a BBO crystal seeds the {{{N}}}2+ gain medium, producing strong narrow-band lasing emission at ∼391 nm. We demonstrate that this scheme can overcome the difficulty in spatially overlapping two beams at a far distance, and the lasing emissions at a designed position can be manipulated by dispersion components inserted in the propagation path of the coaxial two-color beam. Our results provide a way for remote generation of air laser for standoff spectroscopy and detection.

  10. Numerical and experimental study of an annular pulse tube used in the pulse tube cooler

    Science.gov (United States)

    Pang, Xiaomin; Chen, Yanyan; Wang, Xiaotao; Dai, Wei; Luo, Ercang

    2017-12-01

    Multi-stage pulse tube coolers normally use a U-type configuration. For compactness, it is attractive to build a completely co-axial multi-stage pulse tube cooler. In this way, an annular shape pulse tube is inevitable. Although there are a few reports about previous annular pulse tubes, a detailed study and comparison with a circular pulse tube is lacking. In this paper, a numeric model based on CFD software is carried out to compare the annular pulse tube and circular pulse tube used in a single stage in-line type pulse tube cooler with about 10 W of cooling power at 77 K. The length and cross sectional area of the two pulse tubes are kept the same. Simulation results show that the enthalpy flow in the annular pulse tube is lower by 1.6 W (about 11% of the enthalpy flow) compared to that in circular pulse tube. Flow and temperature distribution characteristics are also analyzed in detail. Experiments are then conducted for comparison with an in-line type pulse tube cooler. With the same acoustic power input, the pulse tube cooler with a circular pulse tube obtains 7.88 W of cooling power at 77 K, while using an annular pulse tube leads to a cooling power of 7.01 W, a decrease of 0.9 W (11.4%) on the cooling performance. The study sets the basis for building a completely co-axial two-stage pulse tube cooler.

  11. Patterns of digital volume pulse waveform and pulse transit time in ...

    African Journals Online (AJOL)

    Introduction: Arterial wall changes underlie many disorders of aging and the complications of diseases like hypertension and diabetes mellitus. Analyzing the pulse wave is an easy, noninvasive method used to assess vessel wall stiffness and pulse changes. In this study the digital volume pulse wave and the pulse transit ...

  12. Study on technology of high-frequency pulsed magnetic field strength measurement.

    Science.gov (United States)

    Chen, Yi-Mei; Liu, Zhi-Peng; Yin, Tao

    2012-01-01

    High-frequency transient weak magnetic field is always involved in researches about biomedical engineering field while common magnetic-field sensors cannot work properly at frequencies as high as MHz. To measure the value of MHz-level weak pulsed magnetic-field strength accurately, this paper designs a measurement and calibration method for pulsed magnetic-field. In this paper, a device made of Nonferromagnetic material was independently designed and applied to pulsed magnetic field measurement. It held an accurately relative position between the magnetic field generating coil and the detecting coil. By applying a sinusoidal pulse to the generator, collecting the induced electromotive force of the detector, the final magnetic field strength was worked out through algorithms written in Matlab according to Faraday's Law. Experiments were carried out for measurement and calibration. Experiments showed that, under good stability and consistency, accurate measurement of magnetic-field strength of a sinepulse magnetic-field can be achieved, with frequency at 0.5, 1, 1.5 MHz and strength level at micro-Tesla. Calibration results carried out a measuring relative error about 2.5%.

  13. CW seeded optical parametric amplifier providing wavelength and pulse duration tunable nearly transform limited pulses.

    Science.gov (United States)

    Hädrich, S; Gottschall, T; Rothhardt, J; Limpert, J; Tünnermann, A

    2010-02-01

    An optical parametric amplifier that delivers nearly transform limited pulses is presented. The center wavelength of these pulses can be tuned between 993 nm and 1070 nm and, at the same time, the pulse duration is varied between 206 fs and 650 fs. At the shortest pulse duration the pulse energy was increased up to 7.2 microJ at 50 kHz repetition rate. Variation of the wavelength is achieved by applying a tunable cw seed while the pulse duration can be varied via altering the pump pulse duration. This scheme offers superior flexibility and scaling possibilities.

  14. Pulse Propagation on close conductors

    CERN Document Server

    Dieckmann, A

    2001-01-01

    The propagation and reflection of arbitrarily shaped pulses on non-dispersive parallel conductors of finite length with user defined cross section is simulated employing the discretized telegraph equation. The geometry of the system of conductors and the presence of dielectric material determine the capacities and inductances that enter the calculation. The values of these parameters are found using an iterative Laplace equation solving procedure and confirmed for certain calculable geometries including the line charge inside a box. The evolving pulses and the resulting crosstalk can be plotted at any instant and - in the Mathematica notebook version of this report - be looked at in an animation. As an example a differential pair of microstrips as used in the ATLAS vertex detector is analysed.

  15. Unsplit bipolar pulse forming line

    Science.gov (United States)

    Rhodes, Mark A [Pleasanton, CA

    2011-05-24

    A bipolar pulse forming transmission line module and system for linear induction accelerators having first, second, third, and fourth planar conductors which form a sequentially arranged interleaved stack having opposing first and second ends, with dielectric layers between the conductors. The first and second planar conductors are connected to each other at the first end, and the first and fourth planar conductors are connected to each other at the second end via a shorting plate. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short at the first end a high voltage from the third planar conductor to the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

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

    Science.gov (United States)

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

    2010-06-01

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

  17. Pulsed Scophony laser projection system

    Science.gov (United States)

    Lowry, J. B.; Welford, W. T.; Humphries, M. R.

    1988-10-01

    A novel laser TV projection display has been developed by PA Technology employing the Scophony system with acousto-optic modulators and pulsed lasers. This results in a projection system with greater optical simplicity, higher reliability and reduced power and cooling requirements over similar laser projectors. The technique has been successfully implemented in British Aerospace's Microdome missile training simulator. This paper describes the underlying principles of the design, its operational features and its implementation in the Microdome.

  18. Metal silicides with energetic pulses

    Science.gov (United States)

    D'Anna, E.; Leggieri, G.; Luches, A.; Majni, G.; Nava, F.; Ottaviani, G.

    1986-07-01

    Samples formed of a thin metal film deposited on silicon single crystal were annealed with electron and laser (ruby and excimer) pulses over a wide range of fluences. From a comparison of the experimental results with the temperature profiles of the irradiated samples, it turns out that suicide formation starts when the metal/silicon interface reaches the lowest eutectic temperature of the binary metal/silicon system. The growth rate of reacted layers is of the order of 1 m/s.

  19. Pulse amplitude modulated chlorophyll fluorometer

    Energy Technology Data Exchange (ETDEWEB)

    Greenbaum, Elias; Wu, Jie

    2015-12-29

    Chlorophyll fluorometry may be used for detecting toxins in a sample because of changes in micro algae. A portable lab on a chip ("LOAC") based chlorophyll fluorometer may be used for toxin detection and environmental monitoring. In particular, the system may include a microfluidic pulse amplitude modulated ("PAM") chlorophyll fluorometer. The LOAC PAM chlorophyll fluorometer may analyze microalgae and cyanobacteria that grow naturally in source drinking water.

  20. High Voltage Nanosecond Pulse Generator.

    Science.gov (United States)

    1978-11-01

    pulse to a laser load was desiqned , built , and tested . —- -~~~-~~~~----j ‘~ ~~ _)— ~ --. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ CoIx ~r 1 I

  1. Generation of synchronized signal and pump pulses for an optical ...

    Indian Academy of Sciences (India)

    2015-11-27

    pass geometry in a grating pair based pulse stretcher unit. The pump pulse has been further amplified in a high gain regenerative amplifier. This amplified pulse was used as the pump in an optical parametric chirped pulse ...

  2. Electromagnetic pulses bone healing booster

    Science.gov (United States)

    Sintea, S. R.; Pomazan, V. M.; Bica, D.; Grebenisan, D.; Bordea, N.

    2015-11-01

    Posttraumatic bone restoration triggered by the need to assist and stimulate compensatory bone growth in periodontal condition. Recent studies state that specific electromagnetic stimulation can boost the bone restoration, reaching up to 30% decrease in recovery time. Based on the existing data on the electromagnetic parameters, a digital electronic device is proposed for intra oral mounting and bone restoration stimulation in periodontal condition. The electrical signal is applied to an inductive mark that will create and impregnate magnetic field in diseased tissue. The device also monitors the status of the electromagnetic field. Controlled wave forms and pulse frequency signal at programmable intervals are obtained with optimized number of components and miniaturized using surface mounting devices (SMD) circuits and surface mounting technology (SMT), with enhanced protection against abnormal current growth, given the intra-oral environment. The system is powered by an autonomous power supply (battery), to limit the problems caused by powering medical equipment from the main power supply. Currently the device is used in clinical testing, in cycles of six up to twelve months. Basic principles for the electrical scheme and algorithms for pulse generation, pulse control, electromagnetic field control and automation of current monitoring are presented, together with the friendly user interface, suitable for medical data and patient monitoring.

  3. Slow light pulse propagation in dispersive media

    DEFF Research Database (Denmark)

    Nielsen, Torben Roland; Mørk, Jesper; Lavrinenko, Andrei

    2009-01-01

    We present a theoretical and numerical analysis of pulse propagation in a semiconductor photonic crystal waveguide with embedded quantum dots in a regime where the pulse is subjected to both waveguide and material dispersion. The group index and the transmission are investigated by finite...... broadening or break-up of the pulse may be observed. The transition from linear to nonlinear pulse propagation is quantified in terms of the spectral width of the pulse. To cite this article: T.R. Nielsen et al., C. R. Physique 10 (2009). (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All...

  4. Few-cycle pulse characterization with an acousto-optic pulse shaper.

    Science.gov (United States)

    Cousin, S L; Forget, N; Grün, A; Bates, P K; Austin, Dane R; Biegert, J

    2011-08-01

    An acousto-optic pulse shaper has been used to characterize few-cycle pulses generated in a hollow-core fiber. A grism pair precompensates for the dispersion of the acousto-optic crystal, allowing the full pulse-shaping window to be used for replica generation rather than self-compensation. A 9.4 fs pulse was measured, the shortest ever measured with an acousto-optic pulse shaper, to our knowledge. © 2011 Optical Society of America

  5. Molecular imprinting sensor based on quantum weak measurement.

    Science.gov (United States)

    Li, Dongmei; He, Qinghua; He, Yonghong; Xin, Meiguo; Zhang, Yilong; Shen, Zhiyuan

    2017-08-15

    A new type of sensing protocol, based on a high precision metrology of quantum weak measurement, was first proposed for molecularly imprinted polymers (MIP) sensor. The feasibility, sensitivity and selectivity of weak measurement based MIP (WMMIP) sensor were experimentally demonstrated with bovine serum albumin (BSA). Weak measurement system exhibits high sensitivity to the optical phase shift corresponding to the refractive index change, which is induced by the specific capture of target protein molecules with its recognition sites. The recognition process can be finally characterized by the central wavelength shift of output spectra through weak value amplification. In our experiment, we prepared BSA@MIP with modified reversed-phase microemulsion method, and coated it on the internal surface of measuring channels assembled into the Mach-Zehnder (MZ) interferometer based optical weak measurement system. The design of this home-built optical system makes it possible to detect analyte in real time. The dynamic process of the specific adsorption and concentration response to BSA from 5×10-4 to 5×10-1μg/L was achieved with a limit of detection (LOD) of 8.01×10-12g/L. This WMMIP shows superiority in accuracy, fast response and low cost. Furthermore, real-time monitoring system can creatively promote the performance of MIP in molecular analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Elliptic and weakly coercive systems of operators in Sobolev spaces

    Science.gov (United States)

    Limanskiĭ, D. V.; Malamud, Mark M.

    2008-12-01

    It is known that an elliptic system \\{P_j(x,D)\\}_1^N of order l is weakly coercive in \\overset{\\circ}{W}{}^l_{\\!\\infty}(\\mathbb R^n), that is, all differential monomials of order \\le l-1 on C_0^\\infty(\\mathbb R^n)-functions are subordinated to this system in the L^\\infty-norm. Conditions for the converse result are found and other properties of weakly coercive systems are investigated. An analogue of the de Leeuw-Mirkil theorem is obtained for operators with variable coefficients: it is shown that an operator P(x,D) of n\\ge 3 variables with constant principal part is weakly coercive in \\overset{\\circ}{W}{}^l_{\\!\\infty}(\\mathbb R^n) if and only if it is elliptic. A similar result is obtained for systems \\{P_j(D)\\}_1^N with constant coefficients under the condition n\\ge 2N+1 and with several restrictions on the symbols P_j(\\xi). A complete description of differential polynomials of two variables which are weakly coercive in \\overset{\\circ}{W}{}^l_{\\!\\infty}(\\mathbb R^2) is given. Wide classes of systems with constant coefficients which are weakly coercive in \\overset{\\circ}{W}{}^l_{\\!\\infty}(\\mathbb R^n), but non-elliptic are constructed. Bibliography: 32 titles.

  7. Weak-Values Metrological Techniques for Parameter Estimation

    Science.gov (United States)

    Martinez-Rincon, Julian Rodrigo

    Precision measurements are bounded by the Standard Quantum Limit, and preparing non-classical states is often used to circumvent such a limit. In all cases, it is common to improve the precision in a parameter estimation procedure by averaging measurements of a large ensemble of identically prepared systems. However, such a task cannot be performed indefinitely due to sources of technical noise setting an experimental bound. Weak-Value Amplification (WVA) allows one to overcome some of these issues by amplifying a signal of interest above the technical-noise floor. This built-in robustness to external sources of noise relies on a weak coupling to a meter and postselection. In this document we evaluate, theoretically and experimentally, under what circumstances the technique is superior to non-postselected standard techniques. We also present a novel protocol where a WVA-like response is induced in an optical homodyne-type detection technique. We dub this technique Almost-Balanced Weak Values (ABWV) and present three experimental measurements of different physical velocities to evaluate the practical advantages over the well-known technique of WVA. In addition, we point out the existence of a third postselected-weak-measurements technique for metrology, Inverse Weak Value (IWV), that has been ignored by the scientific community. We use this protocol to measure ultra small tilts of a mirror in a Sagnac interferometer. We report all three techniques as complementary to each other, and show their robustness for low-frequency signals.

  8. Experimentally quantifying the advantages of weak-value-based metrology

    Science.gov (United States)

    Viza, Gerardo I.; Martínez-Rincón, Julián; Alves, Gabriel B.; Jordan, Andrew N.; Howell, John C.

    2015-09-01

    We experimentally investigate the relative advantages of implementing weak-value-based metrology versus standard methods. While the techniques outlined herein apply more generally, we measure small optical beam deflections both using a Sagnac interferometer with a monitored dark port (the weak-value-based technique), and by focusing the entire beam to a split detector (the standard technique). By introducing controlled external transverse detector modulations and transverse beam deflection momentum modulations, we quantify the mitigation of these sources in the weak-value-based experiment versus the standard focusing experiment. The experiments are compared using a combination of deterministic and stochastic methods. In all cases, the weak-value technique performs the same or better than the standard technique by up to two orders of magnitude in precision for our parameters. We further measure the statistical efficiency of the weak-value-based technique. By postselecting on 1 % of the photons, we obtain 99 % of the available Fisher information of the beam deflection parameter.

  9. Spectral Properties of AGN with Very Weak [O III] Lines

    Directory of Open Access Journals (Sweden)

    Kovacevic, J.

    2011-06-01

    Full Text Available The spectral properties of a sample of 58 Active GalacticNuclei (AGN spectra, in which emission [O~III] $lambdalambda$4959, 5007 AA lines are weak or totally absent, are analyzed. In order to investigate thephysical reason for the [O~III] emission suppression, the spectral propertiesof the weak [O~III] spectra sample are compared with the same properties of asample of 269 spectra with the strong [O~III] lines. The spectra are obtainedfrom Sloan Digital Sky Survey (SDSS Database. It is found that the objectswith the weak or absent [O~III] $lambdalambda$4959, 5007 AA linesgenerally have the high continuum luminosities (log($lambda$L$_{5100}$ $>$45, that they are very rare at smaller redshifts ($z <$ 0.3 and that theyusually have strong starburst influence. From the sample with weak or absent[O~III] lines, two boundary subgroups may be distinguished: the subgroup witha strong H$beta$ narrow component and subgroup with a very weak or negligibleH$beta$ narrow component. The physical causes for the [O~III] linessuppressing are probably different in these two subgroups: the [O~III] linesare absent in objects with strong narrow H$beta$ probably because of strongstarburst (SB activity, which produces high density of the gas, while in theobjects with the negligible narrow H$beta$, the reason for [O~III] and narrowH$beta$ suppression may be a low covering factor.

  10. Weak electric fields detectability in a noisy neural network.

    Science.gov (United States)

    Zhao, Jia; Deng, Bin; Qin, Yingmei; Men, Cong; Wang, Jiang; Wei, Xile; Sun, Jianbing

    2017-02-01

    We investigate the detectability of weak electric field in a noisy neural network based on Izhikevich neuron model systematically. The neural network is composed of excitatory and inhibitory neurons with similar ratio as that in the mammalian neocortex, and the axonal conduction delays between neurons are also considered. It is found that the noise intensity can modulate the detectability of weak electric field. Stochastic resonance (SR) phenomenon induced by white noise is observed when the weak electric field is added to the network. It is interesting that SR almost disappeared when the connections between neurons are cancelled, suggesting the amplification effects of the neural coupling on the synchronization of neuronal spiking. Furthermore, the network parameters, such as the connection probability, the synaptic coupling strength, the scale of neuron population and the neuron heterogeneity, can also affect the detectability of the weak electric field. Finally, the model sensitivity is studied in detail, and results show that the neural network model has an optimal region for the detectability of weak electric field signal.

  11. Learning from Weak and Noisy Labels for Semantic Segmentation

    KAUST Repository

    Lu, Zhiwu

    2016-04-08

    A weakly supervised semantic segmentation (WSSS) method aims to learn a segmentation model from weak (image-level) as opposed to strong (pixel-level) labels. By avoiding the tedious pixel-level annotation process, it can exploit the unlimited supply of user-tagged images from media-sharing sites such as Flickr for large scale applications. However, these ‘free’ tags/labels are often noisy and few existing works address the problem of learning with both weak and noisy labels. In this work, we cast the WSSS problem into a label noise reduction problem. Specifically, after segmenting each image into a set of superpixels, the weak and potentially noisy image-level labels are propagated to the superpixel level resulting in highly noisy labels; the key to semantic segmentation is thus to identify and correct the superpixel noisy labels. To this end, a novel L1-optimisation based sparse learning model is formulated to directly and explicitly detect noisy labels. To solve the L1-optimisation problem, we further develop an efficient learning algorithm by introducing an intermediate labelling variable. Extensive experiments on three benchmark datasets show that our method yields state-of-the-art results given noise-free labels, whilst significantly outperforming the existing methods when the weak labels are also noisy.

  12. effect of the plasma ion channel on self-focusing of a Gaussian laser pulse in underdense plasma

    Directory of Open Access Journals (Sweden)

    Sh Irani

    2013-09-01

    Full Text Available  We have considered the self-focusing of a Gaussian laser pulse in unmagnetized plasma. High-intensity electromagnetic fields cause the variation of electron density in plasma. These changes in the special conditions cause the acceleration of electrons to the higher energy and velocities. Thus the equation of plasma density evolution was obtained considering the electrons ponderomotive force. Then, an equation for the width of laser pulse with a relativistic mass correction term and the effect of ion channel were derived and the propagation of high-intensity laser pulse in an underdense plasma with weak relativistic approximation was investigated. It is shown that the ratio of ion channel radius to spot size could result in different forms of self focusing for the laser pulse in plasma.

  13. Quantum weak and modular values in enlarged Hilbert spaces

    Science.gov (United States)

    Ho, Le Bin; Imoto, Nobuyuki

    2018-01-01

    We introduce an enlarged state, which combines both pre- and postselection states at a given time t in between the pre- and postselection. Based on this form, quantum weak and modular values can be completely interpreted as expectation values of a linear combination of given operators in the enlarged Hilbert space. This formalism thus enables us to describe and measure the weak and modular values at any time dynamically. A protocol for implementing an enlarged Hamiltonian has also been proposed and applied to a simple example of a single spin under an external magnetic field. In addition, the time-dependent weak and modular values for pre- and postselection density matrices mapping onto an enlarged density matrix are also discussed.

  14. Identification and classification of weak layers in the snow

    Directory of Open Access Journals (Sweden)

    E. S. Klimenko

    2013-01-01

    Full Text Available The paper considers the role of vertical snowpack structure for snow avalanche formation and describes the idea of «structural instability». It aims at enhancing the knowledge about transition mechanisms between stable and unstable states of snowpack and snow avalanches release. Structural instability implies the presence of weak layer or interface in vertical snowpack profile. Type of snow failure and avalanche characteristics are completely defined by snowpack state and properties. Thus wide variety of genetic types of snow avalanches indicates the existence of structural instability of different types. The detailed analysis of scientific publications and field observations led to the creation of a new classification of weak layers. The layers are classified basing on their cohesiveness, the causes of initial disturbance and internal and external processes which form a weak layer. The classification is a necessary part of global method which allows assessing snowpack stability using modern physical models of snow cover evolution.

  15. Testing the Weak Form Efficiency of Karachi Stock Exchange

    Directory of Open Access Journals (Sweden)

    Muhammad Arshad Haroon

    2012-12-01

    Full Text Available In an efficient market, share prices reflect all available information. The study of efficient market hypothesis helps to take right decisions related to investments. In this research,weak form efficiency has been tested of Karachi Stock Exchange—KSE covering the period of 2nd November 1991 to 2nd November 2011. Descriptive statistics indicated the absence of weak form efficiency while results of non-parametric tests, showed consistency as well. We employed non-parametric tests were KS Goodness-of-Fit test,run test and autocorrelation test to find out serial independency of the data. Results prove that KSE is not weak-form-efficient. This happens because KSE is an emerging market and there, it has been observed that information take time to be processed. Thus it can besaid that technical analysis may be applied to gain abnormal returns.

  16. Non-perturbative aspects in a weakly interacting Higgs sector

    CERN Document Server

    Maas, Axel

    2012-01-01

    Just like the weakly interacting QED can support non-perturbative phenomena, like atoms, so can the weak and Higgs interactions. Especially, there are strong field-theoretical arguments that only bound states can be the (quasi-)asymptotic physical degrees of freedom of this sector. After a brief review of these arguments, the 2-point, 3-point and 4-point correlation functions of the Higgs-W system are determined using lattice gauge theory. The results support a conjectured duality between elementary states and bound states for weak Higgs self-interactions. This leads to relations between the bound states and the experimentally observed particles. Interestingly, these may yield pseudo-scalar admixtures at the Higgs energy, and possibly a faint standard-model signal in the channel where a Kaluza-Klein graviton would be expected.

  17. Enhancing teleportation fidelity by means of weak measurements or reversal

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Liang, E-mail: lqiu@cumt.edu.cn [College of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Tang, Gang; Yang, Xianqing [College of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Wang, Anmin [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)

    2014-11-15

    The enhancement of teleportation fidelity by weak measurement or quantum measurement reversal is investigated. One qubit of a maximally entangled state undergoes the amplitude damping, and the subsequent application of weak measurement or quantum measurement reversal could improve the teleportation fidelity beyond the classical region. The improvement could not be attributed to the increasing of entanglement, quantum discord, classical correlation or total correlation. We declare that it should be owed to the probabilistic nature of the method. - Highlights: • The method’s probabilistic nature should be responsible for the improvement. • Quantum or classical correlation cannot explain the improvement. • The receiver cannot apply weak measurements. • The sender’s quantum measurement reversal is only useful for |Ψ{sup ±}〉.

  18. Competition among networks highlights the power of the weak

    Science.gov (United States)

    Iranzo, Jaime; Buldú, Javier M.; Aguirre, Jacobo

    2016-11-01

    The unpreventable connections between real networked systems have recently called for an examination of percolation, diffusion or synchronization phenomena in multilayer networks. Here we use network science and game theory to explore interactions in networks-of-networks and model these as a game for gaining importance. We propose a viewpoint where networks choose the connection strategies, in contrast with classical approaches where nodes are the active players. Specifically, we investigate how creating paths between networks leads to different Nash equilibria that determine their structural and dynamical properties. In a wide variety of cases, selecting adequate connections leads to a cooperative solution that allows weak networks to overcome the strongest opponent. Counterintuitively, each weak network can induce a global transition to such cooperative configuration regardless of the actions of the strongest network. This power of the weak reveals a critical dominance of the underdogs in the fate of networks-of-networks.

  19. Horizontal mergers and weak and strong competition commissions

    Directory of Open Access Journals (Sweden)

    Ristić Bojan

    2014-01-01

    Full Text Available In this paper we analyse the horizontal merger of companies in an already concentrated industry. The participants in mergers are obliged to submit notification to the Competition Commission but they also have the option of rejecting the merger. At the time of the notification submission the participants do not know whether the Commission is strong or weak, and they can complain to the Court if the Commission prohibits the merger. We model the strategic interaction between Participants and Commission in a dynamic game of incomplete information and determine weak perfect Bayesian equilibria. The main finding of our paper is that Participants will base their decision to submit notification on their belief in a weak Commission decision and will almost completely ignore the possibility of a strong Commission decision. We also provide a detailed examination of one case from Serbian regulatory practice, which coincides with the results of our game theoretical model.

  20. Design and application of pulse information acquisition and analysis ...

    African Journals Online (AJOL)

    Background: To design the pulse information which includes the parameter of pulse-position, pulse-number, pulse-shape and pulse-force acquisition and analysis system with function of dynamic recognition, and research the digitalization and visualization of some common cardiovascular mechanism of single pulse.

  1. Children's ambiguous understanding of weak and strong quantifiers

    Directory of Open Access Journals (Sweden)

    Erik-Jan Smits

    2008-02-01

    Full Text Available Despite suggestions in the literature that the semantics of many might be the key for understanding children’s non-adult-like interpretations of quantified sentences (cf. Drozd 2001, Geurts 2003, experimental data on the acquisition of weak quantifiers like many is rare. This paper investigates children’s comprehension of weak (many versus strong (many of, all quantifiers in English. In particular, by means of a truth-value judgment task, taking the semantic and syntactic characteristics of many into account, we tested whether 28 children aged between four and seven understand the ambiguous nature of many as described in the literature (Partee, 1988 and whether they transfer this ambiguity to many of and all. The results show that children have an ambiguous quantifier system for both strong and weak quantifiers. This runs counter the idea that the child always prefers a reading of many in which the arguments seem to ‘switch’ (as for adults in Many French have won the Tour de France, resulting in the interpretation Many Tour de France winners are French, as predicted by Drozd and Van Loosbroek’s (1999 Weak Quantification Hypothesis. On the basis of our experimental results on children’s understanding of both weak and strong quantifiers, we conclude that children’s non-adult interpretations of quantified sentences are due to the ambiguous nature of (weak quantifiers. This presents the language learner with the difficult, but necessary, task to distinguish between those different kinds of readings and understand their different semantic and syntactic representations in order to converge with the target language.

  2. Temporal-mode measurement tomography of a quantum pulse gate

    Science.gov (United States)

    Ansari, Vahid; Harder, Georg; Allgaier, Markus; Brecht, Benjamin; Silberhorn, Christine

    2017-12-01

    Encoding quantum information in the photon temporal mode (TM) offers a robust platform for high-dimensional quantum protocols. The main practical challenge, however, is to design a device that operates on single photons in specific TMs and all coherent superpositions. The quantum pulse gate (QPG) is a mode-selective sum-frequency generation designed for this task. Here, we perform a full modal characterization of a QPG using weak coherent states in well-defined TMs. We reconstruct a full set of measurement operators, which show an average fidelity of 0.85 to a theoretically ideal device when operating on a seven-dimensional space. Then we use these characterized measurement operators of the QPG to calibrate the device. Using the calibrated device and a tomographically complete set of measurements, we show that the QPG can perform high-dimensional TM state tomography with 0.99 fidelity.

  3. Interaction between counter-propagating quantum Hall edge channels in the 3D topological insulator BiSbTeSe2

    NARCIS (Netherlands)

    Li, Chuan; De Ronde, Bob; Nikitin, Artem; Huang, Yingkai; Golden, Mark S.; De Visser, Anne; Brinkman, Alexander

    2017-01-01

    The quantum Hall effect is studied in the topological insulator BiSbTeSe2. By employing top- and back-gate electric fields at high magnetic field, the Landau levels of the Dirac cones in the top and bottom topological surface states can be tuned independently. When one surface is tuned to the

  4. Weak partial metric spaces and some fixed point results

    Directory of Open Access Journals (Sweden)

    Ishak Altun

    2012-10-01

    Full Text Available The concept of partial metric p on a nonempty set X was introduced by Matthews. One of the most interesting properties of a partial metric is that p(x, x may not be zero for x e X. Also, each partial metric p on a nonempty set X generates a T0 topology on X. By omitting the small self-distance axiom of partial metric, Heckmann defined the weak partial metric space. In the present paper, we give some fixed point results on weak partial metric spaces.

  5. Weak Approximation of SDEs by Discrete-Time Processes

    Directory of Open Access Journals (Sweden)

    Henryk Zähle

    2008-01-01

    Full Text Available We consider the martingale problem related to the solution of an SDE on the line. It is shown that the solution of this martingale problem can be approximated by solutions of the corresponding time-discrete martingale problems under some conditions. This criterion is especially expedient for establishing the convergence of population processes to SDEs. We also show that the criterion yields a weak Euler scheme approximation of SDEs under fairly weak assumptions on the driving force of the approximating processes.

  6. Weak Interaction Studies by Precision Experiments in Nuclear Beta Decay

    Science.gov (United States)

    Severijns, Nathal

    The framework and formalism related to the study of symmetries and the structure of the weak interaction in nuclear -decay are presented and discussed. This is illustrated with a number of selected experiments in nuclear -decay addressing the unitarity of the Cabibbo-Kobayashi-Maskawa matrix, the search for right-handed (V+A), scalar and tensor components in the weak interaction and the search for non-Standard Model sources of time reversal violation. Finally, an outlook is given on important progress in this field that can be expected for the near future.

  7. Weak gravitational lensing with COSMOS : galaxy selection and shape measurements.

    OpenAIRE

    Leauthaud, Alexie; Massey, Richard; Kneib, Jean-Paul; Rhodes, Jason; Johnston, David E.; Capak, Peter; Heymans, Catherine; Ellis, Richard S.; Koekemoer, Anton M.; Le Fevre, Oliver; Mellier, Yannick; Refregier, Alexandre; Robin, Annie C.; Scoville, Nick; Tasca, Lidia

    2007-01-01

    With a primary goal of conducting precision weak-lensing measurements from space, the COSMOS survey has imaged the largest contiguous area observed by Hubble Space Telescope to date, using the Advanced Camera for Surveys (ACS). This is the first paper in a series in which we describe our strategy for addressing the various technical challenges in the production of weak-lensing measurements from COSMOS data. We first construct a source catalog from 575 ACS/WFC tiles (1.64 deg^2) subsampled at ...

  8. Power control for wind turbines in weak grids: Project summary

    OpenAIRE

    Bindner, H.

    1999-01-01

    In many parts of the world and certainly in Europe large areas exist where the wind resources are good or very good and the grid is relatively weak due to a small population. In these areas the capacity of the grid can very often be a limiting factor forthe exploitation of the wind resource. There are two main problems concerned with wind power and weak grids. The first is the steady state voltage level. When the power consumption is low e.g. during the night the voltage of the grid can incre...

  9. A weak equivalence principle test on a suborbital rocket

    Energy Technology Data Exchange (ETDEWEB)

    Reasenberg, Robert D; Phillips, James D, E-mail: reasenberg@cfa.harvard.ed [Smithsonian Astrophysical Observatory, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

    2010-05-07

    We describe a Galilean test of the weak equivalence principle, to be conducted during the free fall portion of a sounding rocket flight. The test of a single pair of substances is aimed at a measurement uncertainty of sigma(eta) < 10{sup -16} after averaging the results of eight separate drops. The weak equivalence principle measurement is made with a set of four laser gauges that are expected to achieve 0.1 pm Hz{sup -1/2}. The discovery of a violation (eta not = 0) would have profound implications for physics, astrophysics and cosmology.

  10. A weak equivalence principle test on a suborbital rocket

    CERN Document Server

    Reasenberg, Robert D

    2010-01-01

    We describe a Galilean test of the weak equivalence principle, to be conducted during the free fall portion of a sounding rocket flight. The test of a single pair of substances is aimed at a measurement uncertainty of sigma(eta) < 10^-16 after averaging the results of eight separate drops. The weak equivalence principle measurement is made with a set of four laser gauges that are expected to achieve 0.1 pm Hz^-1/2. The discovery of a violation (eta not equal to 0) would have profound implications for physics, astrophysics, and cosmology.

  11. Weak Molecular Interactions in Clathrin-Mediated Endocytosis

    Science.gov (United States)

    Smith, Sarah M.; Baker, Michael; Halebian, Mary; Smith, Corinne J.

    2017-01-01

    Clathrin-mediated endocytosis is a process by which specific molecules are internalized from the cell periphery for delivery to early endosomes. The key stages in this step-wise process, from the starting point of cargo recognition, to the later stage of assembly of the clathrin coat, are dependent on weak interactions between a large network of proteins. This review discusses the structural and functional data that have improved our knowledge and understanding of the main weak molecular interactions implicated in clathrin-mediated endocytosis, with a particular focus on the two key proteins: AP2 and clathrin.

  12. Measurements of weak localization of graphene in inhomogeneous magnetic fields

    DEFF Research Database (Denmark)

    Lindvall, N.; Shivayogimath, Abhay; Yurgens, A.

    2015-01-01

    attribute this to the inhomogeneous field caused by vortices in the superconductor. The deviation, which depends on the carrier concentration in graphene, can be tuned by the gate voltage. In addition, collective vortex motion, known as vortex avalanches, is observed through magnetoresistance measurements......Weak localization in graphene is studied in inhomogeneous magnetic fields. To generate the inhomogeneous field, a thin film of type-II superconducting niobium is put in close proximity to graphene. A deviation from the ordinary quadratic weak localization behavior is observed at low fields. We...... of graphene....

  13. Processing on weak electric signals by the autoregressive model

    Science.gov (United States)

    Ding, Jinli; Zhao, Jiayin; Wang, Lanzhou; Li, Qiao

    2008-10-01

    A model of the autoregressive model of weak electric signals in two plants was set up for the first time. The result of the AR model to forecast 10 values of the weak electric signals is well. It will construct a standard set of the AR model coefficient of the plant electric signal and the environmental factor, and can be used as the preferences for the intelligent autocontrol system based on the adaptive characteristic of plants to achieve the energy saving on agricultural productions.

  14. On Weak and Strong 2k- bent Boolean Functions

    Science.gov (United States)

    2016-01-01

    no. 1, 34–64; translation in J. Appl. Ind. Math . 5:1 (2011), 110–129. [17] N. Tokareva, Bent Functions – Results and Applications to Cryptogra- phy...On weak and strong 2k-bent Boolean functions Pantelimon Stănică Department of Applied Mathematics Naval Postgraduate School Monterey, CA 93943-5212... functions , which we shall call (weak, strong) octa/hexadeca and in general, 2k-bent functions . We investigate relationships between these classes and

  15. Bubble, weak and strong hyperinflation: Theory and empirical evidence

    Directory of Open Access Journals (Sweden)

    Fernando de Holanda Barbosa

    2015-05-01

    Full Text Available This paper presents a theoretical framework that allows a taxonomy of hyperinflation, namely: (i bubble, (ii weak and (iii strong hyperinflation. The inflation tax revenue curve is used to characterize each type of hyperinflation and we use this curve to test them. The bubble and strong hyperinflation hypotheses are rejected using Brazilian data. The weak hyperinflation hypothesis is not rejected and the economy could have been on the ‘wrong’ side of the Laffer curve during hyperinflation. This outcome, contrary to conventional wisdom, is predicted by this hypothesis, which presents a solution to an old puzzle of the hyperinflation literature.

  16. High-redshift SDSS Quasars with Weak Emission Lines

    DEFF Research Database (Denmark)

    Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Brandt, W. N.

    2009-01-01

    We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a prominent...... rest-frame 0.1-5 µm spectral energy distributions that are quite similar to those of normal quasars. The variability, polarization, and radio properties of WLQs are also different from those of BL Lacs, making continuum boosting by a relativistic jet an unlikely physical interpretation. The most...

  17. A Weak Comparison Principle for Reaction-Diffusion Systems

    Directory of Open Access Journals (Sweden)

    José Valero

    2012-01-01

    Full Text Available We prove a weak comparison principle for a reaction-diffusion system without uniqueness of solutions. We apply the abstract results to the Lotka-Volterra system with diffusion, a generalized logistic equation, and to a model of fractional-order chemical autocatalysis with decay. Moreover, in the case of the Lotka-Volterra system a weak maximum principle is given, and a suitable estimate in the space of essentially bounded functions L∞ is proved for at least one solution of the problem.

  18. Fuzzy Weak Regular, Strong and Preassociative Filters in Residuated Lattices

    Directory of Open Access Journals (Sweden)

    Wei Yang

    2014-06-01

    Full Text Available In this paper, the notions of fuzzy weak regular, strong and preassociative filters are introduced with some properties of them investigated. In particular, under the context of Glivenko algebras, fuzzy weak regular filters and regular ones are equivalent and characterizations of Glivenko algebras are concluded by characterizations of fuzzy strong filters. At last the notion of fuzzy preassociative filters are defined, which are proved to coincide with fuzzy Boolean filters, and then some new alternative definitions of Boolean algebras are obtained by this type of filters.

  19. Observation of Weak Collapse in a Bose-Einstein Condensate

    Directory of Open Access Journals (Sweden)

    Christoph Eigen

    2016-12-01

    Full Text Available We study the collapse of an attractive atomic Bose-Einstein condensate prepared in the uniform potential of an optical-box trap. We characterize the critical point for collapse and the collapse dynamics, observing universal behavior in agreement with theoretical expectations. Most importantly, we observe a clear experimental signature of the counterintuitive weak collapse, namely, that making the system more unstable can result in a smaller particle loss. We experimentally determine the scaling laws that govern the weak-collapse atom loss, providing a benchmark for the general theories of nonlinear wave phenomena.

  20. Observation of Weak Collapse in a Bose-Einstein Condensate

    Science.gov (United States)

    Eigen, Christoph; Gaunt, Alexander L.; Suleymanzade, Aziza; Navon, Nir; Hadzibabic, Zoran; Smith, Robert P.

    2016-10-01

    We study the collapse of an attractive atomic Bose-Einstein condensate prepared in the uniform potential of an optical-box trap. We characterize the critical point for collapse and the collapse dynamics, observing universal behavior in agreement with theoretical expectations. Most importantly, we observe a clear experimental signature of the counterintuitive weak collapse, namely, that making the system more unstable can result in a smaller particle loss. We experimentally determine the scaling laws that govern the weak-collapse atom loss, providing a benchmark for the general theories of nonlinear wave phenomena.