Peculiarities of the propagation of multidimensional extremely short optical pulses in germanene

Energy Technology Data Exchange (ETDEWEB)

Zhukov, Alexander V., E-mail: alex_zhukov@sutd.edu.sg [Singapore University of Technology and Design, 8 Somapah Road, 487372 Singapore (Singapore); Bouffanais, Roland [Singapore University of Technology and Design, 8 Somapah Road, 487372 Singapore (Singapore); Konobeeva, Natalia N. [Volgograd State University, 400062 Volgograd (Russian Federation); Belonenko, Mikhail B. [Laboratory of Nanotechnology, Volgograd Institute of Business, 400048 Volgograd (Russian Federation); Volgograd State University, 400062 Volgograd (Russian Federation)

2016-09-07

Highlights: • Established dynamics of ultra-short pulses in germanene. • Studied balance between dispersive and nonlinear effects in germanene. • Spin–orbit interaction effect onto pulse propagation. - Abstract: In this Letter, we study the propagation characteristics of both two-dimensional and three-dimensional extremely short optical pulses in germanene. A distinguishing feature of germanene—in comparison with other graphene-like structures—is the presence of a significant spin–orbit interaction. The account of this interaction has a significant impact on the evolution of extremely short pulses in such systems. Specifically, extremely short optical pulses, consisting of two electric field oscillations, cause the appearance of a tail associated with the excitation of nonlinear waves. Due to the large spin–orbit interaction in germanene, this tail behind the main pulse is much smaller in germanene-based samples as compared to graphene-based ones, thereby making germanene a preferred material for the stable propagation of pulses along the sample.

A Novel Method for Short Distance Measurements

International Nuclear Information System (INIS)

Fernandez, M.G.; Ferrando, A.; Josa, M.I.; Molinero, A.; Oller, J.C.; Arce, P.; Calvo, E.; Figueroa, C.F.; Garcia, C.F.; Rodigrido, T.; Vila, I.; Virto, A.L.

1998-01-01

A new, accurate and un expensive device for measuring short distances, intended for monitoring in LHC experiments is presented. Data taken with a very simple prototype are shown and performance is extracted. (Author) 4 refs

Nonlinear propagation of short wavelength drift-Alfven waves

DEFF Research Database (Denmark)

Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

1986-01-01

Making use of a kinetic ion and a hydrodynamic electron description together with the Maxwell equation, the authors derive a set of nonlinear equations which governs the dynamics of short wavelength ion drift-Alfven waves. It is shown that the nonlinear drift-Alfven waves can propagate as two-dim...

Single Neurons in the Avian Auditory Cortex Encode Individual Identity and Propagation Distance in Naturally Degraded Communication Calls.

Science.gov (United States)

Mouterde, Solveig C; Elie, Julie E; Mathevon, Nicolas; Theunissen, Frédéric E

2017-03-29

One of the most complex tasks performed by sensory systems is "scene analysis": the interpretation of complex signals as behaviorally relevant objects. The study of this problem, universal to species and sensory modalities, is particularly challenging in audition, where sounds from various sources and localizations, degraded by propagation through the environment, sum to form a single acoustical signal. Here we investigated in a songbird model, the zebra finch, the neural substrate for ranging and identifying a single source. We relied on ecologically and behaviorally relevant stimuli, contact calls, to investigate the neural discrimination of individual vocal signature as well as sound source distance when calls have been degraded through propagation in a natural environment. Performing electrophysiological recordings in anesthetized birds, we found neurons in the auditory forebrain that discriminate individual vocal signatures despite long-range degradation, as well as neurons discriminating propagation distance, with varying degrees of multiplexing between both information types. Moreover, the neural discrimination performance of individual identity was not affected by propagation-induced degradation beyond what was induced by the decreased intensity. For the first time, neurons with distance-invariant identity discrimination properties as well as distance-discriminant neurons are revealed in the avian auditory cortex. Because these neurons were recorded in animals that had prior experience neither with the vocalizers of the stimuli nor with long-range propagation of calls, we suggest that this neural population is part of a general-purpose system for vocalizer discrimination and ranging. SIGNIFICANCE STATEMENT Understanding how the brain makes sense of the multitude of stimuli that it continually receives in natural conditions is a challenge for scientists. Here we provide a new understanding of how the auditory system extracts behaviorally relevant information

Short-distance perturbation theory for the leading logarithm models

International Nuclear Information System (INIS)

Adler, S.L.

1983-01-01

I derive a short-distance perturbation expansion for the static potential of quasi-abelian quark and antiquark source charges, in the models in which renormalization group radiative corrections are retained in the gauge gluon effective dielectric functional. A natural running coupling parameter zeta for the models is identified, and the scale mass #betta#sub(p) appearing in zeta is computed by requiring the vanishing of the O(zeta 2 ) term in the perturbation expansions. The models are shown to give unsatisfactory results beyond one-loop order in the short-distance expansion, as a result of the breakdown in the ultraviolet of the assumption that the effective action is a local functional of the field strength. The same argument indicates that the assumption of a local effective action becomes self-consistent in the large-distance limit. The coupling parameter zeta is identified as a running coupling which evolves in field strength, rather than momentum, and which becomes infinite in the large-distance limit. (orig.)

Hawking radiation from acoustic black holes, short distance and back reaction effects

International Nuclear Information System (INIS)

Balbinot, R.; Fabbri, A.; Parentani, R.

2004-01-01

Using the action principle we first review how linear density perturbations (sound waves) in an Eulerian fluid obey a relativistic equation: the d'Alembert equation. This analogy between propagation of sound and that of a massless scalar field in a Lorentzian metric also applies to non-homogeneous flows. In these cases, sound waves effectively propagate in a curved four-dimensional acoustic metric whose properties are determined by the flow. Using this analogy, we consider regular flows which become supersonic, and show that the acoustic metric behaves like that of a black hole. The analogy is so good that, when considering quantum mechanics, acoustic black holes should produce a thermal flux of Hawking phonons. We then focus on two interesting questions related to Hawking radiation which are not fully understood in the context of gravitational black holes due to the lack of a theory of quantum gravity. The first concerns the calculation of the modifications of Hawking radiation which are induced by dispersive effects at short distances, approaching the atomic scale when considering sound. We generalize existing treatments and calculate the modifications caused by the propagation near the black-hole horizon. The second question concerns back reaction effects. We return to the Eulerian action, compute second-order effects, and show that the back reaction of sound waves on the fluid's flow can be expressed in terms of their stress-energy tensor. Using this result in the context of Hawking radiation, we compute the secular effect on the background flow

Short distance modification of the quantum virial theorem

Science.gov (United States)

Zhao, Qin; Faizal, Mir; Zaz, Zaid

2017-07-01

In this letter, we will analyse the deformation of a semi-classical gravitational system from minimal measurable length scale. In the semi-classical approximation, the gravitational field will be analysed as a classical field, and the matter fields will be treated quantum mechanically. Thus, using this approximation, this system will be represented by a deformation of Schrödinger-Newton equation by the generalised uncertainty principle (GUP). We will analyse the effects of this GUP deformed Schrödinger-Newton equation on the behaviour of such a semi-classical gravitational system. As the quantum mechanical virial theorem can be obtained using the Schrödinger-Newton equation, a short distance modification of the Schrödinger-Newton equation will also result in a short distance modification of the quantum mechanical virial theorem.

Allowable propagation of short pulse laser beam in a plasma channel and electromagnetic solitary waves

International Nuclear Information System (INIS)

Zhang, Shan; Hong, Xue-Ren; Wang, Hong-Yu; Xie, Bai-Song

2011-01-01

Nonparaxial and nonlinear propagation of a short intense laser beam in a parabolic plasma channel is analyzed by means of the variational method and nonlinear dynamics. The beam propagation properties are classified by five kinds of behaviors. In particularly, the electromagnetic solitary wave for finite pulse laser is found beside the other four propagation cases including beam periodically oscillating with defocussing and focusing amplitude, constant spot size, beam catastrophic focusing. It is also found that the laser pulse can be allowed to propagate in the plasma channel only when a certain relation for laser parameters and plasma channel parameters is satisfied. For the solitary wave, it may provide an effective way to obtain ultra-short laser pulse.

Latent lifestyle and mode choice decisions when travelling short distances

DEFF Research Database (Denmark)

Prato, Carlo Giacomo; Halldórsdóttir, Katrín; Nielsen, Otto Anker

2016-01-01

In the quest for sustainable travel, short distances appear the most amenable to curbing the use of the automobile. Existing studies about short trips evaluate the potential of shifting from the automobile to sustainable travel options while considering the population as homogeneous in its prefer...

Propagation engineering in radio links design

CERN Document Server

Ghasemi, Abdollah; Ghasemi, Farshid

2013-01-01

Propagation Engineering in Radio Link Design covers the basic principles of radiowaves propagation in a practical manner.  This fundamental understanding enables the readers to design radio links efficiently. This book elaborates on new achievements as well as recently developed propagation models.  This is in addition to a comprehensive overview of fundamentals of propagation in various scenarios. It examines theoretical calculations, approaches and applied procedures needed for radio links design. The authors study and analysis of the main propagation phenomena and its mechanisms based on the recommendations of International Telecommunications Union, (ITU). The book has been organized in 9 chapters and examines the role of antennas and passive reflectors in radio services, propagation mechanisms related to radar, satellite, short distance, broadcasting and trans-horizon radio links, with two chapters devoted to radio noise and main  parameters of radio link design. The book presents some 278 illustration...

Short-pulse propagation in fiber optical parametric amplifiers

DEFF Research Database (Denmark)

Cristofori, Valentina

Fiber optical parametric amplifiers (FOPAs) are attractive because they can provide large gain over a broad range of central wavelengths, depending only on the availability of a suitable pump laser. In addition, FOPAs are suitable for the realization of all-optical signal processing functionalities...... transfer can be reduced in saturated F OPAs. In order to characterize propagation impairments such as dispersion and Kerr effect, affecting signals reaching multi-terabit per second per channel, short pulses on the order of 500 fs need to be considered. Therefore, a short pulses fiber laser source...... is implemented to obtain an all-fiber system. The advantages of all fiber-systems are related to their reliability, long-term stability and compactness. Fiber optical parametric chirped pulse amplification is promising for the amplification of such signals thanks to the inherent compatibility of FOPAs with fiber...

Relics of short distance effects for the neutron electric dipole moment

International Nuclear Information System (INIS)

Eeg, J.O.

1982-12-01

The Feynman diagrams which dominate the estimates of the electric dipole moment of the neutron with Kobayashi-Maskawa CP violation are considered. The extracted long distance contributions and the relics of short distance contributions are shown to be complementary and of the same magnitude, resulting in mod(Dsub(n)/e) approximately = (10 - 31 - 10 - 30 ) cm. (Auth.)

Separation of source and propagation effects at regional distances

Energy Technology Data Exchange (ETDEWEB)

Goldstein, P.; Jarpe, S.; Mayeda, K. [Lawrence Livermore National Lab., CA (United States)] [and others

1994-12-31

Improved estimates of the contributions of source and propagation effects to regional seismic signals are needed to explain the performance of existing discriminants and to help develop more robust methods for identifying underground explosions. In this paper, we use close-in, local, and regional estimates of explosion source time functions to remove source effects from regional recordings of the Non-Proliferation Experiment (NPE), a one kiloton chemical explosion in N-tunnel at Rainier Mesa on the Nevada Test Site, and nearby nuclear explosions and earthquakes. Using source corrected regional waveforms, we find that regional Pg and Lg spectra of shallow explosions have significant low frequency ({approximately}1Hz) enhancements when compared to normal depth earthquakes. Data and simulations suggest that such enhancements are most sensitive to source depth, but may also be a function of mechanism, source receiver distance, and regional structure.

Simulation of long-distance beam propagation in the Paul trap simulator experiment

International Nuclear Information System (INIS)

Gilson, Erik P.; Chung, Moses; Davidson, Ronald C.; Efthimion, Philip C.; Majeski, Richard; Startsev, Edward A.

2005-01-01

The Paul Trap Simulator Experiment (PTSX) simulates the propagation of intense charged particle beams over distances of many kilometers through magnetic alternating-gradient (AG) transport systems by making use of the similarity between the transverse dynamics of particles in the two systems. One-component pure ion plasmas have been trapped that correspond to normalized intensity parameter s-coret=ω p 2 (0)/2ω q 2 = p (r) is the plasma frequency and ω q is the average transverse focusing frequency in the smooth-focusing approximation. The PTSX device confines one-component cesium ion plasmas for hundreds of milliseconds, which is equivalent to beam propagation over 10km. Results are presented for experiments in which the amplitude of the confining voltage waveform has been modified as a function of time. Recent modifications to the device are described, and both the change from a cesium ion source to a barium ion source, and the development of a laser-induced fluorescence diagnostic system are discussed

Effect of short-term overloads on crack propagation under creep

International Nuclear Information System (INIS)

Sushok, V.V.; Sobolev, N.D.; Zolotukhin, S.Yu.

1986-01-01

Kinetics of crack propagation after overload has been studied using plane samples of Kh18N10T steel. Tests of samples with a notch have been carried out in the air at 293 K. Observation of the crack growth has been carried out by the microscope and the method of electric potential difference. It is established that during overload besides crack tip blunting, decrease of creep rate of the material stregthened near it, that leads to crack retardation, decrease of plasticity and formation of microcracks in front of the tip of the main-line crack occurs. It is marked that, estimating serviceability of a member, it is necessary to take into account the decrease of crack propagation rate after short term overloads

Microstructural Abnormalities of Short-Distance White Matter Tracts in Autism Spectrum Disorder

Science.gov (United States)

Shukla, Dinesh K.; Keehn, Brandon; Smylie, Daren M.; Muller, Ralph-Axel

2011-01-01

Recent functional connectivity magnetic resonance imaging and diffusion tensor imaging (DTI) studies have suggested atypical functional connectivity and reduced integrity of long-distance white matter fibers in autism spectrum disorder (ASD). However, evidence for short-distance white matter fibers is still limited, despite some speculation of…

Study of phonon propagation in water using picosecond ultrasonics

International Nuclear Information System (INIS)

Yang, F; Atay, T; Dang, C H; Grimsley, T J; Che, S; Ma, J; Zhang, Q; Nurmikko, A V; Maris, H J

2007-01-01

The propagation of ultra-short sound pulses in water is studied by using the picosecond ultrasonic technique. A sound pulse is generated when light is absorbed in a metal transducer film deposited onto a substrate. The sound propagates across a thin layer of water and is then reflected back to the surface at which it was generated. The efficiency of optoacoustic detection of the reflected sound is enhanced through the use of a resonant optical cavity. We show that the variation of the shape of the returning sound pulse with propagation distance agrees with that calculated by using the attenuation of sound in water that has been measured at lower frequencies

Self-organization of high intensity laser pulses propagating in gases

International Nuclear Information System (INIS)

Koga, James

2001-01-01

In recent years the development of high intensity short pulse lasers has opened up wide fields of science which had previously been difficult to study. Recent experiments of short pulse lasers propagating in air have shown that these laser pulses can propagate over very long distances (up to 12 km) with little or no distortion of the pulse. Here we present a model of this propagation using a modified version of the self-organized criticality model developed for sandpiles by Bak, Tang, and Weisenfeld. The additions to the sandpile model include the formation of plasma which acts as a threshold diffusion term and self-focusing by the nonlinear index of refraction which acts as a continuous inverse diffusion. Results of this simple model indicate that a strongly self-focusing laser pulse shows self-organized critical behavior. (author)

Dynamic characteristic of intense short microwave propagation in an atmosphere

International Nuclear Information System (INIS)

Yee, J.H.; Alvarez, R.A.; Mayhall, D.J.; Madsen, N.K.; Cabayan, H.S.

1983-07-01

The dynamic behavior of an intense microwave pulse which propagates through the atmosphere will be presented. Our theoretical results are obtained by solving Maxwell's equations, together with the electron fluid equations. Our calculations show that although large portions of the initial energy are absorbed by the electrons that are created through the avalanche process, a significant amount of energy is still able to reach the earth's surface. The amount of energy that reaches the earth's surface as a function of initial energy and wave shape after having propagated through 100 km in the atmosphere are investigated. Results for the air breakdown threshold intensity as a function of the pressure for different pulse widths and different frequencies will also be presented. In addition, we will present a comparison between the theoretical and the experimental results for the pulse shape of a short microwave pulse after it has traveled through a rectangular wave guide which contains a section of air. 23 references, 9 figures

Particle transport patterns of short-distance soil erosion by wind-driven rain, rain and wind

Science.gov (United States)

Marzen, Miriam; Iserloh, Thomas; de Lima, João L. M. P.; Ries, Johannes B.

2015-04-01

Short distance erosion of soil surface material is one of the big question marks in soil erosion studies. The exact measurement of short-distance transported soil particles, prior to the occurrence of overland flow, is a challenge to soil erosion science due to the particular requirements of the experimental setup and test procedure. To approach a quantification of amount and distance of each type of transport, we applied an especially developed multiple-gutter system installed inside the Trier Portable Wind and Rainfall Simulator (PWRS). We measured the amount and travel distance of soil particles detached and transported by raindrops (splash), wind-driven rain (splash-saltation and splash-drift) and wind (saltation). The test setup included three different erosion agents (rain/ wind-driven rain/ wind), two substrates (sandy/ loamy), three surface structures (grain roughness/ rills lengthwise/ rills transversal) and three slope angles (0°/+7°/-7°). The results present detailed transport patterns of the three erosion agents under the varying soil and surface conditions up to a distance of 1.6 m. Under the applied rain intensity and wind velocity, wind-driven rain splash generates the highest erosion. The erodibility and travel distance of the two substrates depend on the erosion agent. The total erosion is slightly higher for the slope angle -7° (downslope), but for wind-driven rain splash, the inclination is not a relevant factor. The effect of surface structures (rills) changes with traveling distance. The wind driven rain splash generates a much higher amount of erosion and a further travel distance of the particles due to the combined action of wind and rain. The wind-driven rain factor appears to be much more significant than the other factors. The study highlights the effects of different erosion agents and surface parameters on short-distance particle transport and the powerful impact of wind-driven rain on soil erosion.

Simulating the Long-Distance Propagation of Intense Beams in the Paul Trap Simulator Experiment

CERN Document Server

Gilson, Erik P; Davidson, Ronald C; Efthimion, Philip; Majeski, Richard; Startsev, Edward

2005-01-01

The Paul Trap Simulator Experiment (PTSX) makes use of a compact Paul trap configuration with quadrupolar oscillating wall voltages to simulate the propagation of intense charged particle beams over distances of many kilometers through magnetic alternating-gradient transport systems. The simulation is possible because of the similarity between the transverse dynamics of particles in the two systems. One-component pure cesium ion plasmas have been trapped that correspond to normalized intensity parameters s < 0.8, where s is the ratio of the square of the plasma frequency to twice the square of the average transverse focusing frequency. The PTSX device confines the plasma for hundreds of milliseconds, which is equivalent to beam propagation over tens of kilometers. Results are presented for experiments in which the amplitude of the oscillating confining voltage waveform has been modified as a function of time. A comparison is made between abrupt changes in amplitude and adiabatic changes in amplitude. T...

Femtosecond frequency comb based distance measurement in air.

Science.gov (United States)

Balling, Petr; Kren, Petr; Masika, Pavel; van den Berg, S A

2009-05-25

Interferometric measurement of distance using a femtosecond frequency comb is demonstrated and compared with a counting interferometer displacement measurement. A numerical model of pulse propagation in air is developed and the results are compared with experimental data for short distances. The relative agreement for distance measurement in known laboratory conditions is better than 10(-7). According to the model, similar precision seems feasible even for long-distance measurement in air if conditions are sufficiently known. It is demonstrated that the relative width of the interferogram envelope even decreases with the measured length, and a fringe contrast higher than 90% could be obtained for kilometer distances in air, if optimal spectral width for that length and wavelength is used. The possibility of comb radiation delivery to the interferometer by an optical fiber is shown by model and experiment, which is important from a practical point of view.

Photoluminescence decay dynamics in γ-Ga2O3 nanocrystals: The role of exclusion distance at short time scales

Science.gov (United States)

Fernandes, Brian; Hegde, Manu; Stanish, Paul C.; Mišković, Zoran L.; Radovanovic, Pavle V.

2017-09-01

We developed a comprehensive theoretical model describing the photoluminescence decay dynamics at short and long time scales based on the donor-acceptor defect interactions in γ-Ga2O3 nanocrystals, and quantitatively determined the importance of exclusion distance and spatial distribution of defects. We allowed for donors and acceptors to be adjacent to each other or separated by different exclusion distances. The optimal exclusion distance was found to be comparable to the donor Bohr radius and have a strong effect on the photoluminescence decay curve at short times. The importance of the exclusion distance at short time scales was confirmed by Monte Carlo simulations.

Measurement of the phase difference between short- and long-distance amplitudes in the [Formula: see text] decay.

Science.gov (United States)

Aaij, R; Adeva, B; Adinolfi, M; Ajaltouni, Z; Akar, S; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amerio, S; Amhis, Y; An, L; Anderlini, L; Andreassi, G; Andreotti, M; Andrews, J E; Appleby, R B; Archilli, F; d'Argent, P; Arnau Romeu, J; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Baalouch, M; Babuschkin, I; Bachmann, S; Back, J J; Badalov, A; Baesso, C; Baker, S; Balagura, V; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Baszczyk, M; Batozskaya, V; Batsukh, B; Battista, V; Bay, A; Beaucourt, L; Beddow, J; Bedeschi, F; Bediaga, I; Bel, L J; Bellee, V; Belloli, N; Belous, K; Belyaev, I; Ben-Haim, E; Bencivenni, G; Benson, S; Berezhnoy, A; Bernet, R; Bertolin, A; Betancourt, C; Betti, F; Bettler, M-O; van Beuzekom, M; Bezshyiko, Ia; Bifani, S; Billoir, P; Bird, T; Birnkraut, A; Bitadze, A; Bizzeti, A; Blake, T; Blanc, F; Blouw, J; Blusk, S; Bocci, V; Boettcher, T; Bondar, A; Bondar, N; Bonivento, W; Bordyuzhin, I; Borgheresi, A; Borghi, S; Borisyak, M; Borsato, M; Bossu, F; Boubdir, M; Bowcock, T J V; Bowen, E; Bozzi, C; Braun, S; Britsch, M; Britton, T; Brodzicka, J; Buchanan, E; Burr, C; Bursche, A; Buytaert, J; Cadeddu, S; Calabrese, R; Calvi, M; Calvo Gomez, M; Camboni, A; Campana, P; Campora Perez, D H; Capriotti, L; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carniti, P; Carson, L; Carvalho Akiba, K; Casse, G; Cassina, L; Castillo Garcia, L; Cattaneo, M; Cavallero, G; Cenci, R; Chamont, D; Charles, M; Charpentier, Ph; Chatzikonstantinidis, G; Chefdeville, M; Chen, S; Cheung, S-F; Chobanova, V; Chrzaszcz, M; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coco, V; Cogan, J; Cogneras, E; Cogoni, V; Cojocariu, L; Collazuol, G; Collins, P; Comerma-Montells, A; Contu, A; Cook, A; Coombs, G; Coquereau, S; Corti, G; Corvo, M; Costa Sobral, C M; Couturier, B; Cowan, G A; Craik, D C; Crocombe, A; Cruz Torres, M; Cunliffe, S; Currie, R; D'Ambrosio, C; Da Cunha Marinho, F; Dall'Occo, E; Dalseno, J; David, P N Y; Davis, A; De Bruyn, K; De Capua, S; De Cian, M; De Miranda, J M; De Paula, L; De Serio, M; De Simone, P; Dean, C-T; Decamp, D; Deckenhoff, M; Del Buono, L; Demmer, M; Dendek, A; Derkach, D; Deschamps, O; Dettori, F; Dey, B; Di Canto, A; Dijkstra, H; Dordei, F; Dorigo, M; Dosil Suárez, A; Dovbnya, A; Dreimanis, K; Dufour, L; Dujany, G; Dungs, K; Durante, P; Dzhelyadin, R; Dziurda, A; Dzyuba, A; Déléage, N; Easo, S; Ebert, M; Egede, U; Egorychev, V; Eidelman, S; Eisenhardt, S; Eitschberger, U; Ekelhof, R; Eklund, L; Ely, S; Esen, S; Evans, H M; Evans, T; Falabella, A; Farley, N; Farry, S; Fay, R; Fazzini, D; Ferguson, D; Fernandez Prieto, A; Ferrari, F; Ferreira Rodrigues, F; Ferro-Luzzi, M; Filippov, S; Fini, R A; Fiore, M; Fiorini, M; Firlej, M; Fitzpatrick, C; Fiutowski, T; Fleuret, F; Fohl, K; Fontana, M; Fontanelli, F; Forshaw, D C; Forty, R; Franco Lima, V; Frank, M; Frei, C; Fu, J; Funk, W; Furfaro, E; Färber, C; Gallas Torreira, A; Galli, D; Gallorini, S; Gambetta, S; Gandelman, M; Gandini, P; Gao, Y; Garcia Martin, L M; García Pardiñas, J; Garra Tico, J; Garrido, L; Garsed, P J; Gascon, D; Gaspar, C; Gavardi, L; Gazzoni, G; Gerick, D; Gersabeck, E; Gersabeck, M; Gershon, T; Ghez, Ph; Gianì, S; Gibson, V; Girard, O G; Giubega, L; Gizdov, K; Gligorov, V V; Golubkov, D; Golutvin, A; Gomes, A; Gorelov, I V; Gotti, C; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graverini, E; Graziani, G; Grecu, A; Griffith, P; Grillo, L; Gruberg Cazon, B R; Grünberg, O; Gushchin, E; Guz, Yu; Gys, T; Göbel, C; Hadavizadeh, T; Hadjivasiliou, C; Haefeli, G; Haen, C; Haines, S C; Hall, S; Hamilton, B; Han, X; Hansmann-Menzemer, S; Harnew, N; Harnew, S T; Harrison, J; Hatch, M; He, J; Head, T; Heister, A; Hennessy, K; Henrard, P; Henry, L; van Herwijnen, E; Heß, M; Hicheur, A; Hill, D; Hombach, C; Hopchev, H; Hulsbergen, W; Humair, T; Hushchyn, M; Hutchcroft, D; Idzik, M; Ilten, P; Jacobsson, R; Jaeger, A; Jalocha, J; Jans, E; Jawahery, A; Jiang, F; John, M; Johnson, D; Jones, C R; Joram, C; Jost, B; Jurik, N; Kandybei, S; Karacson, M; Kariuki, J M; Karodia, S; Kecke, M; Kelsey, M; Kenzie, M; Ketel, T; Khairullin, E; Khanji, B; Khurewathanakul, C; Kirn, T; Klaver, S; Klimaszewski, K; Koliiev, S; Kolpin, M; Komarov, I; Koopman, R F; Koppenburg, P; Kosmyntseva, A; Kozachuk, A; Kozeiha, M; Kravchuk, L; Kreplin, K; Kreps, M; Krokovny, P; Kruse, F; Krzemien, W; Kucewicz, W; Kucharczyk, M; Kudryavtsev, V; Kuonen, A K; Kurek, K; Kvaratskheliya, T; Lacarrere, D; Lafferty, G; Lai, A; Lanfranchi, G; Langenbruch, C; Latham, T; Lazzeroni, C; Le Gac, R; van Leerdam, J; Leflat, A; Lefrançois, J; Lefèvre, R; Lemaitre, F; Lemos Cid, E; Leroy, O; Lesiak, T; Leverington, B; Li, T; Li, Y; Likhomanenko, T; Lindner, R; Linn, C; Lionetto, F; Liu, X; Loh, D; Longstaff, I; Lopes, J H; Lucchesi, D; Lucio Martinez, M; Luo, H; Lupato, A; Luppi, E; Lupton, O; Lusiani, A; Lyu, X; Machefert, F; Maciuc, F; Maev, O; Maguire, K; Malde, S; Malinin, A; Maltsev, T; Manca, G; Mancinelli, G; Manning, P; Maratas, J; Marchand, J F; Marconi, U; Marin Benito, C; Marinangeli, M; Marino, P; Marks, J; Martellotti, G; Martin, M; Martinelli, M; Martinez Santos, D; Martinez Vidal, F; Martins Tostes, D; Massacrier, L M; Massafferri, A; Matev, R; Mathad, A; Mathe, Z; Matteuzzi, C; Mauri, A; Maurice, E; Maurin, B; Mazurov, A; McCann, M; McNab, A; McNulty, R; Meadows, B; Meier, F; Meissner, M; Melnychuk, D; Merk, M; Merli, A; Michielin, E; Milanes, D A; Minard, M-N; Mitzel, D S; Mogini, A; Molina Rodriguez, J; Monroy, I A; Monteil, S; Morandin, M; Morawski, P; Mordà, A; Morello, M J; Morgunova, O; Moron, J; Morris, A B; Mountain, R; Muheim, F; Mulder, M; Mussini, M; Müller, D; Müller, J; Müller, K; Müller, V; Naik, P; Nakada, T; Nandakumar, R; Nandi, A; Nasteva, I; Needham, M; Neri, N; Neubert, S; Neufeld, N; Neuner, M; Nguyen, T D; Nguyen-Mau, C; Nieswand, S; Niet, R; Nikitin, N; Nikodem, T; Nogay, A; Novoselov, A; O'Hanlon, D P; Oblakowska-Mucha, A; Obraztsov, V; Ogilvy, S; Oldeman, R; Onderwater, C J G; Otalora Goicochea, J M; Otto, A; Owen, P; Oyanguren, A; Pais, P R; Palano, A; Palombo, F; Palutan, M; Papanestis, A; Pappagallo, M; Pappalardo, L L; Parker, W; Parkes, C; Passaleva, G; Pastore, A; Patel, G D; Patel, M; Patrignani, C; Pearce, A; Pellegrino, A; Penso, G; Pepe Altarelli, M; Perazzini, S; Perret, P; Pescatore, L; Petridis, K; Petrolini, A; Petrov, A; Petruzzo, M; Picatoste Olloqui, E; Pietrzyk, B; Pikies, M; Pinci, D; Pistone, A; Piucci, A; Placinta, V; Playfer, S; Plo Casasus, M; Poikela, T; Polci, F; Poluektov, A; Polyakov, I; Polycarpo, E; Pomery, G J; Popov, A; Popov, D; Popovici, B; Poslavskii, S; Potterat, C; Price, E; Price, J D; Prisciandaro, J; Pritchard, A; Prouve, C; Pugatch, V; Puig Navarro, A; Punzi, G; Qian, W; Quagliani, R; Rachwal, B; Rademacker, J H; Rama, M; Ramos Pernas, M; Rangel, M S; Raniuk, I; Ratnikov, F; Raven, G; Redi, F; Reichert, S; Dos Reis, A C; Remon Alepuz, C; Renaudin, V; Ricciardi, S; Richards, S; Rihl, M; Rinnert, K; Rives Molina, V; Robbe, P; Rodrigues, A B; Rodrigues, E; Rodriguez Lopez, J A; Rodriguez Perez, P; Rogozhnikov, A; Roiser, S; Rollings, A; Romanovskiy, V; Romero Vidal, A; Ronayne, J W; Rotondo, M; Rudolph, M S; Ruf, T; Ruiz Valls, P; Saborido Silva, J J; Sadykhov, E; Sagidova, N; Saitta, B; Salustino Guimaraes, V; Sanchez Mayordomo, C; Sanmartin Sedes, B; Santacesaria, R; Santamarina Rios, C; Santimaria, M; Santovetti, E; Sarti, A; Satriano, C; Satta, A; Saunders, D M; Savrina, D; Schael, S; Schellenberg, M; Schiller, M; Schindler, H; Schlupp, M; Schmelling, M; Schmelzer, T; Schmidt, B; Schneider, O; Schopper, A; Schubert, K; Schubiger, M; Schune, M-H; Schwemmer, R; Sciascia, B; Sciubba, A; Semennikov, A; Sergi, A; Serra, N; Serrano, J; Sestini, L; Seyfert, P; Shapkin, M; Shapoval, I; Shcheglov, Y; Shears, T; Shekhtman, L; Shevchenko, V; Siddi, B G; Silva Coutinho, R; Silva de Oliveira, L; Simi, G; Simone, S; Sirendi, M; Skidmore, N; Skwarnicki, T; Smith, E; Smith, I T; Smith, J; Smith, M; Snoek, H; Soares Lavra, L; Sokoloff, M D; Soler, F J P; Souza De Paula, B; Spaan, B; Spradlin, P; Sridharan, S; Stagni, F; Stahl, M; Stahl, S; Stefko, P; Stefkova, S; Steinkamp, O; Stemmle, S; Stenyakin, O; Stevens, H; Stevenson, S; Stoica, S; Stone, S; Storaci, B; Stracka, S; Straticiuc, M; Straumann, U; Sun, L; Sutcliffe, W; Swientek, K; Syropoulos, V; Szczekowski, M; Szumlak, T; T'Jampens, S; Tayduganov, A; Tekampe, T; Tellarini, G; Teubert, F; Thomas, E; van Tilburg, J; Tilley, M J; Tisserand, V; Tobin, M; Tolk, S; Tomassetti, L; Tonelli, D; Topp-Joergensen, S; Toriello, F; Tournefier, E; Tourneur, S; Trabelsi, K; Traill, M; Tran, M T; Tresch, M; Trisovic, A; Tsaregorodtsev, A; Tsopelas, P; Tully, A; Tuning, N; Ukleja, A; Ustyuzhanin, A; Uwer, U; Vacca, C; Vagnoni, V; Valassi, A; Valat, S; Valenti, G; Vazquez Gomez, R; Vazquez Regueiro, P; Vecchi, S; van Veghel, M; Velthuis, J J; Veltri, M; Veneziano, G; Venkateswaran, A; Vernet, M; Vesterinen, M; Viana Barbosa, J V; Viaud, B; Vieira, D; Vieites Diaz, M; Viemann, H; Vilasis-Cardona, X; Vitti, M; Volkov, V; Vollhardt, A; Voneki, B; Vorobyev, A; Vorobyev, V; Voß, C; de Vries, J A; Vázquez Sierra, C; Waldi, R; Wallace, C; Wallace, R; Walsh, J; Wang, J; Ward, D R; Wark, H M; Watson, N K; Websdale, D; Weiden, A; Whitehead, M; Wicht, J; Wilkinson, G; Wilkinson, M; Williams, M; Williams, M P; Williams, M; Williams, T; Wilson, F F; Wimberley, J; Wishahi, J; Wislicki, W; Witek, M; Wormser, G; Wotton, S A; Wraight, K; Wyllie, K; Xie, Y; Xing, Z; Xu, Z; Yang, Z; Yao, Y; Yin, H; Yu, J; Yuan, X; Yushchenko, O; Zarebski, K A; Zavertyaev, M; Zhang, L; Zhang, Y; Zhang, Y; Zhelezov, A; Zheng, Y; Zhu, X; Zhukov, V; Zucchelli, S

2017-01-01

A measurement of the phase difference between the short- and long-distance contributions to the [Formula: see text] decay is performed by analysing the dimuon mass distribution. The analysis is based on pp collision data corresponding to an integrated luminosity of 3[Formula: see text] collected by the LHCb experiment in 2011 and 2012. The long-distance contribution to the [Formula: see text] decay is modelled as a sum of relativistic Breit-Wigner amplitudes representing different vector meson resonances decaying to muon pairs, each with their own magnitude and phase. The measured phases of the [Formula: see text] and [Formula: see text] resonances are such that the interference with the short-distance component in dimuon mass regions far from their pole masses is small. In addition, constraints are placed on the Wilson coefficients, [Formula: see text] and [Formula: see text], and the branching fraction of the short-distance component is measured.

Long and Short Distance Migration in Italy : The Role of Economic, Social and Environmental Characteristics

NARCIS (Netherlands)

Biagi, Bianca; Faggian, Alessandra; McCann, Philip

2011-01-01

This paper analyses Italian interregional migration flows. The approach taken is to decompose labour mobility flows into short distance and long distance migration and to model the effects of economic variables, social capital and quality of life variables, and amenity variables, on the mobility

Application of affinity propagation algorithm based on manifold distance for transformer PD pattern recognition

Science.gov (United States)

Wei, B. G.; Huo, K. X.; Yao, Z. F.; Lou, J.; Li, X. Y.

2018-03-01

It is one of the difficult problems encountered in the research of condition maintenance technology of transformers to recognize partial discharge (PD) pattern. According to the main physical characteristics of PD, three models of oil-paper insulation defects were set up in laboratory to study the PD of transformers, and phase resolved partial discharge (PRPD) was constructed. By using least square method, the grey-scale images of PRPD were constructed and features of each grey-scale image were 28 box dimensions and 28 information dimensions. Affinity propagation algorithm based on manifold distance (AP-MD) for transformers PD pattern recognition was established, and the data of box dimension and information dimension were clustered based on AP-MD. Study shows that clustering result of AP-MD is better than the results of affinity propagation (AP), k-means and fuzzy c-means algorithm (FCM). By choosing different k values of k-nearest neighbor, we find clustering accuracy of AP-MD falls when k value is larger or smaller, and the optimal k value depends on sample size.

Scattering and short-distance properties in field theory models

International Nuclear Information System (INIS)

Iagolnitzer, D.

1987-01-01

The aim of constructive field theory is not only to define models but also to establish their general properties of physical interest. We here review recent works on scattering and on short-distance properties for weakly coupled theories with mass gap such as typically P(φ) in dimension 2, φ 4 in dimension 3 and the (renormalizable, asymptotically free) massive Gross-Neveu (GN) model in dimension 2. Many of the ideas would apply similarly to other (possibly non renormalizable) theories that might be defined in a similar way via phase-space analysis

Heat wave propagation in a thin film irradiated by ultra-short laser pulses

International Nuclear Information System (INIS)

Yoo, Jae Gwon; Kim, Cheol Jung; Lim, C. H.

2004-01-01

A thermal wave solution of a hyperbolic heat conduction equation in a thin film is developed on the basis of the Green's function formalism. Numerical computations are carried out to investigate the temperature response and the propagation of the thermal wave inside a thin film due to a heat pulse generated by ultra-short laser pulses with various laser pulse durations and thickness of the film

Lifetimes of #betta#'s and μ's and short-distance nuclear phenomena

International Nuclear Information System (INIS)

Kisslinger, L.S.

1982-06-01

It is shown that short distance phenomena and thus quark structure play vital roles in the theory of #betta# and μ decays in nuclei. A hybrid two-baryon-quark shell model is used to estimate the lifetimes for nonmesonic decays of #betta#'s and μ's in nuclear matter

Glucose uptake patterns in exercised skeletal muscles of elite male long-distance and short-distance runners.

Science.gov (United States)

Tai, Suh-Jun; Liu, Ren-Shyan; Kuo, Ya-Chen; Hsu, Chi-Yang; Chen, Chi-Hsien

2010-04-30

The aim of this study was to determine glucose uptake patterns in exercised skeletal muscles of elite male long-distance and short-distance runners. Positron emission tomography (PET) using 18F-fluoro-2-deoxyglucose (FDG) was performed to determine the patterns of glucose uptake in lower limbs of short-distance (SD group, n=8) and long-distance (LD group, n=8) male runners after a modified 20 min Bruce treadmill test. Magnetic resonance imaging (MRI) was used to delineate the muscle groups in lower limbs. Muscle groups from hip, knee, and ankle movers were measured. The total FDG uptake and the standard uptake value (SUV) for each muscle group were compared between the 2 groups. For the SD and LD runners, the 2 major muscle groups utilizing glucose during running were knee extensors and ankle plantarflexors, which accounted for 49.3 +/- 8.1% (25.1 +/- 4.7% and 24.2 +/- 6.0%) of overall lower extremity glucose uptake for SD group, and 51.3 +/- 8.0% (27.2 +/- 2.7% and 24.0 +/- 8.1%) for LD group. No difference in muscle glucose uptake was noted for other muscle groups. For SD runners, the SUVs for the muscle groups varied from 0.49 +/- 0.27 for the ankle plantarflexors, to 0.20 +/- 0.08 for the hip flexor. For the LD runners, the highest and lowest SUVs were 0.43 +/- 0.15 for the ankle dorsiflexors and 0.21 +/- 0.19 for the hip. For SD and LD groups, no difference in muscle SUV was noted for the muscle groups. However, the SUV ratio between the ankle dorsiflexors and plantarflexors in the LD group was significantly greater than that in the SD group. We thus conclude that the major propelling muscle groups account for approximately 50% of lower limb glucose utilization during running. Thus, the other muscle groups involving maintenance of balance, limb deceleration, and shock absorption utilize an equal amount. This result provides a new insight into glucose distribution in skeletal muscle, suggesting that propellers and supporters are both energetically important

Modeling of competitive activity of skilled athletes specialized at 1500 m distance on short-track skating

Directory of Open Access Journals (Sweden)

O.S. Kholodova

2013-10-01

Full Text Available Background: Models of competitive activity at the 1500 m distance on short-track skating are developed on the basis of defining the relationship between sports results and major characteristics which describe speed of running at different parts of the distance. Material: we analyzed reports of competitions at the European and World Championships, World Cups 2007-2011. The dynamics of the speed finalists of the competition at the 1500 m - in hits (n = 33, quarterfinals (n = 34, semi-finals (n = 32 and finals (n = 39. Results: it was determined that for a distance of 1500 m short track skating is the most appropriate model with factors of influence: the speed of the first to sixth part of distance , the speed difference between the first and second half of the distance, time of the slowest circle, the difference between the time of the slowest and fastest circles. Conclusions: time of overcoming of distance will diminish at the rational change of model indexes. It will allow to increase possibility of output in the next circle of competitions and accordingly improve a place in final protocol.

On the short-distance double penguin contribution to the K0 - anti K0 mixing

International Nuclear Information System (INIS)

Eeg, J.O.

1985-04-01

The short-distance contribution of the double penguin box diagram to the K 0 - anti K 0 mixing is investigated. Compared with previous work of other authors, the present paper takes into account the momentum dependence of the box loop, both the non-local part of the penguin and the previously considered local part and the crossed diagrams, which make a class of double penguin diagrams complete. With such new ingredients, is is concluded that the short-distance part of the double penguin is physically irrelevant. After eliminating this particular mechanism for the K 0 - anti K 0 mixing, other potentially relevant mechanisms are pointed out

On cutoff effects in lattice QCD from short to long distances

International Nuclear Information System (INIS)

Della Morte, Michele; Sommer, Rainer; Takeda, Shinji

2009-01-01

We discuss kinematical enhancements of cutoff effects at short and intermediate distances. Starting from a pedagogical example with periodic boundary conditions, we switch to the case of the Schroedinger functional, where the theoretical analysis is checked by precise numerical data with N f =2 dynamical O(a)-improved Wilson quarks. Finally we present an improved determination of the renormalization of the axial current in that theory

On cutoff effects in lattice QCD from short to long distances

International Nuclear Information System (INIS)

Della Morte, Michele; Sommer, Rainer; Takeda, Shinji

2008-07-01

We discuss kinematical enhancements of cutoff effects at short and intermediate distances. Starting from a pedagogical example with periodic boundary conditions, we switch to the case of the Schroedinger functional, where the theoretical analysis is checked by precise numerical data with N f =2 dynamical O(a)-improved Wilson quarks. Finally we present an improved determination of the renormalization of the axial current in that theory. (orig.)

A short working distance multiple crystal x-ray spectrometer

Science.gov (United States)

Dickinson, B.; Seidler, G.T.; Webb, Z.W.; Bradley, J.A.; Nagle, K.P.; Heald, S.M.; Gordon, R.A.; Chou, I.-Ming

2008-01-01

For x-ray spot sizes of a few tens of microns or smaller, a millimeter-sized flat analyzer crystal placed ???1 cm from the sample will exhibit high energy resolution while subtending a collection solid angle comparable to that of a typical spherically bent crystal analyzer (SBCA) at much larger working distances. Based on this observation and a nonfocusing geometry for the analyzer optic, we have constructed and tested a short working distance (SWD) multicrystal x-ray spectrometer. This prototype instrument has a maximum effective collection solid angle of 0.14 sr, comparable to that of 17 SBCA at 1 m working distance. We find good agreement with prior work for measurements of the Mn K?? x-ray emission and resonant inelastic x-ray scattering for MnO, and also for measurements of the x-ray absorption near-edge structure for Dy metal using L??2 partial-fluorescence yield detection. We discuss future applications at third- and fourth-generation light sources. For concentrated samples, the extremely large collection angle of SWD spectrometers will permit collection of high-resolution x-ray emission spectra with a single pulse of the Linac Coherent Light Source. The range of applications of SWD spectrometers and traditional multi-SBCA instruments has some overlap, but also is significantly complementary. ?? 2008 American Institute of Physics.

Why Did the Fault Rupture of the 2008 Wenchuan Earthquake Propagate Predominately Northeastwards?

Science.gov (United States)

Zhu, S.; Yuan, J.

2017-12-01

The rupture processes of the 2008 Wenchuan earthquake are much complex. The rupture propagated northeastward a large distance as long as 300 km, but rupture length is short in the southwest direction. Although a great deal of attention has been paid to why the rupture propagated preponderantly northeastward in the 2008 Wenchuan earthquake, the physical mechanism remains unclear. By means of finite element model, in which bimaterial contrast across the Longmen Shan fault is taken into account, nucleation process is initiated at the center of the fault, ruptures then spread out outward spontaneously in both directions. The simulated results show that the different materials between both sides of the fault lead to tensile changes of normal stresses on the fault, which enhance the propagation of the ruptures in northeastward direction. We found that bimaterial mechanism is important for earthquake ruptures, and mode II rupture evolves with propagation distance along a bimaterial interface to a unilateral wrinkle-like Weertman pulse in the direction of slip on the more compliant side of the fault, namely in the positive direction (i.e, the northeast direction in the study). The Weertman pulse can be self-amplified, self-sustained and self-healing, which gives rise to little frictional energy and long propagation distance. This may be the reason why the Wenchuan earthquake is a unilateral fault rupture and a high seismic magnitude. In addition, the modelling results suggest that the rupture distance is much smaller if the material in the model is homogeneous, in which no huge earthquakes can occur like the 2008 Wenchan event. This research was jointly supported by the National Natural Science Foundation of China (41574041), Beijing Natural Science Foundation (8152034), and by Basic Research Project (ZDJ2017-08).

On cutoff effects in lattice QCD from short to long distances

Energy Technology Data Exchange (ETDEWEB)

Della Morte, Michele [CERN, Physics Department, TH Division, Geneva (Switzerland); Sommer, Rainer [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Takeda, Shinji [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik

2008-07-15

We discuss kinematical enhancements of cutoff effects at short and intermediate distances. Starting from a pedagogical example with periodic boundary conditions, we switch to the case of the Schroedinger functional, where the theoretical analysis is checked by precise numerical data with N{sub f}=2 dynamical O(a)-improved Wilson quarks. Finally we present an improved determination of the renormalization of the axial current in that theory. (orig.)

Topological effects in QCD and the problem of short-distance singularities

International Nuclear Information System (INIS)

Luescher, Martin

2004-01-01

The topological susceptibility and the higher moments of the topological charge distribution in QCD are expressed through certain n-point functions of the scalar and pseudo-scalar quark densities at vanishing momenta, which are free of short-distance singularities. Since the normalization of the correlation functions is determined by the non-singlet chiral Ward identities, these formulae provide an unambiguous regularization-independent definition of the moments and thus of the charge distribution

Prediction of short-distance aerial movement of Phakopsora pachyrhizi urediniospores using machine learning

Science.gov (United States)

Dispersal of urediniospores by wind is the primary means of spread for Phakopsora pachyrhizi, the cause of soybean rust. Our research focused on the short distance movement of urediniospores from within the soybean canopy and up to 61 m from field-grown soybean rust infected plants. Environmental va...

Nonlinear propagation analysis of few-optical-cycle pulses for subfemtosecond compression and carrier envelope phase effect

International Nuclear Information System (INIS)

Mizuta, Yo; Nagasawa, Minoru; Ohtani, Morimasa; Yamashita, Mikio

2005-01-01

A numerical approach called Fourier direct method (FDM) is applied to nonlinear propagation of optical pulses with the central wavelength 800 nm, the width 2.67-12.00 fs, and the peak power 25-6870 kW in a fused-silica fiber. Bidirectional propagation, delayed Raman response, nonlinear dispersion (self-steepening, core dispersion), as well as correct linear dispersion are incorporated into 'bidirectional propagation equations' which are derived directly from Maxwell's equations. These equations are solved for forward and backward waves, instead of the electric-field envelope as in the nonlinear Schroedinger equation (NLSE). They are integrated as multidimensional simultaneous evolution equations evolved in space. We investigate, both theoretically and numerically, the validity and the limitation of assumptions and approximations used for deriving the NLSE. Also, the accuracy and the efficiency of the FDM are compared quantitatively with those of the finite-difference time-domain numerical approach. The time-domain size 500 fs and the number of grid points in time 2048 are chosen to investigate numerically intensity spectra, spectral phases, and temporal electric-field profiles up to the propagation distance 1.0 mm. On the intensity spectrum of a few-optical-cycle pulses, the self-steepening, core dispersion, and the delayed Raman response appear as dominant, middle, and slight effects, respectively. The delayed Raman response and the core dispersion reduce the effective nonlinearity. Correct linear dispersion is important since it affects the intensity spectrum sensitively. For the compression of femtosecond optical pulses by the complete phase compensation, the shortness and the pulse quality of compressed pulses are remarkably improved by the intense initial peak power rather than by the short initial pulse width or by the propagation distance longer than 0.1 mm. They will be compressed as short as 0.3 fs below the damage threshold of fused-silica fiber 6 MW. It

Formation of metal nanoparticles by short-distance sputter deposition in a reactive ion etching chamber

International Nuclear Information System (INIS)

Nie Min; Meng, Dennis Desheng; Sun Kai

2009-01-01

A new method is reported to form metal nanoparticles by sputter deposition inside a reactive ion etching chamber with a very short target-substrate distance. The distribution and morphology of nanoparticles are found to be affected by the distance, the ion concentration, and the sputtering time. Densely distributed nanoparticles of various compositions were fabricated on the substrates that were kept at a distance of 130 μm or smaller from the target. When the distance was increased to 510 μm, island structures were formed, indicating the tendency to form continuous thin film with longer distance. The observed trend for nanoparticle formation is opposite to the previously reported mechanism for the formation of nanoparticles by sputtering. A new mechanism based on the seeding effect of the substrate is proposed to interpret the experimental results.

Physiological characteristics of elite short- and long-distance triathletes.

Science.gov (United States)

Millet, Grégoire P; Dréano, Patrick; Bentley, David J

2003-01-01

The purpose of this study was to compare the physiological responses in cycling and running of elite short-distance (ShD) and long-distance (LD) triathletes. Fifteen elite male triathletes participating in the World Championships were divided into two groups (ShD and LD) and performed a laboratory trial that comprised submaximal treadmill running, maximal then submaximal ergometry cycling and then an additional submaximal run. "In situ" best ShD triathlon performances were also analysed for each athlete. ShD demonstrated a significantly faster swim time than LD whereas .VO(2max) (ml kg(-1) min(-1)), cycling economy (W l(-1) min(-1)), peak power output (.W(peak),W) and ventilatory threshold (%.VO(2max)) were all similar between ShD and LD. Moreover, there were no differences between the two groups in the change (%) in running economy from the first to the second running bout. Swimming time was correlated to .W(peak)(r=-0.76; Ptriathlon was correlated to .W(peak)(r=-0.83; P<0.05) in LD. In conclusion, ShD triathletes had a faster swimming time but did not exhibit different maximal or submaximal physiological characteristics measured in cycling and running than LD triathletes.

Short Distance Standoff Raman Detection of Extra Virgin Olive Oil Adulterated with Canola and Grapeseed Oils.

Science.gov (United States)

Farley, Carlton; Kassu, Aschalew; Bose, Nayana; Jackson-Davis, Armitra; Boateng, Judith; Ruffin, Paul; Sharma, Anup

2017-06-01

A short distance standoff Raman technique is demonstrated for detecting economically motivated adulteration (EMA) in extra virgin olive oil (EVOO). Using a portable Raman spectrometer operating with a 785 nm laser and a 2-in. refracting telescope, adulteration of olive oil with grapeseed oil and canola oil is detected between 1% and 100% at a minimum concentration of 2.5% from a distance of 15 cm and at a minimum concentration of 5% from a distance of 1 m. The technique involves correlating the intensity ratios of prominent Raman bands of edible oils at 1254, 1657, and 1441 cm -1 to the degree of adulteration. As a novel variation in the data analysis technique, integrated intensities over a spectral range of 100 cm -1 around the Raman line were used, making it possible to increase the sensitivity of the technique. The technique is demonstrated by detecting adulteration of EVOO with grapeseed and canola oils at 0-100%. Due to the potential of this technique for making measurements from a convenient distance, the short distance standoff Raman technique has the promise to be used for routine applications in food industry such as identifying food items and monitoring EMA at various checkpoints in the food supply chain and storage facilities.

Measuring short distance dispersal of Alliaria petiolata and determining potential long distance dispersal mechanisms

Directory of Open Access Journals (Sweden)

Christopher A. Loebach

2018-03-01

were dropped on furs and rotated as before, then the furs were agitated for one hour. The seeds retained in the fur were counted. Results For the seed dispersal experiment, the 2Dt function provided the best fit and was the most biologically meaningful. It predicted that seed density rapidly declined with distance from the point source. Mean dispersal distance was 0.52 m and 95% of seeds dispersed within 1.14 m. The epizoochory field experiment showed increased mammal activity and A. petiolata seedlings in germination trays of the MIT compared to control. Laboratory studies showed 3–26% of seeds were attached and retained by raccoon and deer fur. Retention significantly increased if either seed or fur were wet (57–98%. Discussion Without animal seed vectors, most seeds fall within a short distance of the seed source; however, long distance dispersal may be accomplished by epizoochory. Our data are consistent with A. petiolata’s widespread distribution and development of dense clusters of the species in invaded areas.

Epidemic propagation on adaptive coevolutionary networks with preferential local-world reconnecting strategy

International Nuclear Information System (INIS)

Song Yu-Rong; Jiang Guo-Ping; Gong Yong-Wang

2013-01-01

In the propagation of an epidemic in a population, individuals adaptively adjust their behavior to avoid the risk of an epidemic. Differently from existing studies where new links are established randomly, a local link is established preferentially in this paper. We propose a new preferentially reconnecting edge strategy depending on spatial distance (PR-SD). For the PR-SD strategy, the new link is established at random with probability p and in a shortest distance with the probability 1 − p. We establish the epidemic model on an adaptive network using Cellular Automata, and demonstrate the effectiveness of the proposed model by numerical simulations. The results show that the smaller the value of parameter p, the more difficult the epidemic spread is. The PR-SD strategy breaks long-range links and establishes as many short-range links as possible, which causes the network efficiency to decrease quickly and the propagation of the epidemic is restrained effectively. (general)

Two-photon collisions and short-distance tests of quantum chromodynamics

International Nuclear Information System (INIS)

Brodsky, S.J.

1978-12-01

The physics of two-photon collisions in e +- storage rings is reviewed with emphasis on the predictions of perturbative quantum chromodynamics for high transverse momentum reactions. It is noted that because of the remarkable scaling properties predicted by the theory, two-photon collisions may be proved one of the cleanest tests of the quantum chromodynamics picture of short distance hadron dynamics. In order to contrast these predictions for photon-induced reactions with those for incident hadrons, predictions from quantum chromodynamics for hadron structure functions and form factors at large momentum transfer are also discussed. 55 references

Fundamental tests and measures of the structure of matter at short distances

International Nuclear Information System (INIS)

Brodsky, S.J.

1981-07-01

Recent progress in gauge field theories has led to a new perspective on the structure of matter and basic interactions at short distances. It is clear that at very high energies quantum electrodynamics, together with the weak and strong interactions, are part of a unified theory with new fundamental constants, new symmetries, and new conservation laws. A non-technical introduction to these topics is given, with emphasis on fundamental tests and measurements. 21 references

On short-distance CP-violating contributions to the KL,S→γγ processes

International Nuclear Information System (INIS)

Eeg, J.O.

1987-07-01

New short-distance penguin-induced quark diagrams for K o anti (K o ) → γγ within the standard model are considered. These diagrams leave the total CP-conserving amplitude essentially unchanged. However, the CP-violating amplitude receives a sizeable contribution comparable with the pole contribution, which has so far been considered to be the only contribution including direct CP-violation

Propagation of short-period gravity waves at high-latitudes during the MaCWAVE winter campaign

Directory of Open Access Journals (Sweden)

K. Nielsen

2006-07-01

Full Text Available As part of the MaCWAVE (Mountain and Convective Waves Ascending Vertically winter campaign an all-sky monochromatic CCD imager has been used to investigate the properties of short-period mesospheric gravity waves at high northern latitudes. Sequential measurements of several nightglow emissions were made from Esrange, Sweden, during a limited period from 27–31 January 2003. Coincident wind measurements over the altitude range (~80–100 km using two meteor radar systems located at Esrange and Andenes have been used to perform a novel investigation of the intrinsic properties of five distinct wave events observed during this period. Additional lidar and MSIS model temperature data have been used to investigate their nature (i.e. freely propagating or ducted. Four of these extensive wave events were found to be freely propagating with potential source regions to the north of Scandinavia. No evidence was found for strong orographic forcing by short-period waves in the airglow emission layers. The fifth event was most unusual exhibiting an extensive, but much smaller and variable wavelength pattern that appeared to be embedded in the background wind field. Coincident wind measurements indicated the presence of a strong shear suggesting this event was probably due to a large-scale Kelvin-Helmholtz instability.

Hadronic wave functions at short distances and the operator product expansion

International Nuclear Information System (INIS)

Brodsky, S.J.; Lepage, G.P.

1980-01-01

The operator product expansion, of appropriate products of quark fields, is used to find the anamalous dimensions which control the short distance behavior of hadronic wave functions. This vehavior in turn controls the high-Q 2 limit of hadronic form factors. In particular, we relate each anamalous dimension of the nonsinglet structure functions to a corresponding logarithmic correction factor to the nominal αsub(s)(Q 2 )/Q 2 fall off of meson form factors. Unlike the case of deep inelastic lepton-hadron scattering, the operator product necessary here involves extra terms which do not contribute to forward matrix elements. (orig.)

Perturbative renormalization of composite operators via flow equations. Pt. 2. Short distance expansion

Energy Technology Data Exchange (ETDEWEB)

Keller, G. (Max-Planck-Institut fuer Physik, Muenchen (Germany). Werner-Heisenberg-Institut); Kopper, C. (Goettingen Univ. (Germany). Inst. fuer Theoretische Physik)

1993-04-01

We give a rigorous and very detailed derivation of the short distance expansion for a product of two arbitrary composite operators in the framework of the perturbative Euclidean massive [Phi][sub 4][sup 4]. The technically almost trivial proof rests on an extension of the differential flow equation method to Green functions with bilocal insertions, for which we also establish a set of generalized Zimmermann identities and Lowenstein rules. (orig.).

Modification of quantum mechanics at short distances: a simple approach to confinement and asymptotic freedom

International Nuclear Information System (INIS)

Mahajan, S.M.; Qadir, A.; Valanju, P.M.

1979-07-01

To make quantum mechanics a suitable description of short-distance (less than or equal to 10 -13 cm) physics, a spatial variation of Planck's constant anti h is introduced. It is shown that the new theory implies asymptotic freedom and quark confinement in a simple way. 10 references

Short distance modifications to Newton's law in SUSY braneworld scenarios

International Nuclear Information System (INIS)

Palma, G.A.

2007-10-01

In braneworld models coming from string theory one generally encounters massless scalar degrees of freedom -moduli- parameterizing the volume of small compact extra-dimensions. Here we discuss the effects of such moduli on Newton's law for a fairly general 5-D supersymmetric braneworld scenario with a bulk scalar field φ.We show that the Newtonian potential describing the gravitational interaction between two bodies localized on the visible brane picks up a non-trivial contribution at short distances that depends on the shape of the superpotential W(φ) of the theory. In particular, we compute this contribution for dilatonic braneworld scenarios W(φ) ∝ e αφ (where a is a constant) and discuss the particular case of 5-D Heterotic M-theory. (orig.)

Shock Wave Propagation in Layered Planetary Interiors: Revisited

Science.gov (United States)

Arkani-Hamed, J.; Monteux, J.

2017-12-01

The end of the terrestrial planet accretion is characterized by numerous large impacts. About 90% of the mass of a large planet is accreted while the core mantle separation is occurring, because of the accretionary and the short-lived radio-isotope heating. The characteristics of the shockwave propagation, hence the existing scaling laws are poorly known within the layered planets. Here, we use iSALE-2D hydrocode simulations to calculate shock pressure in a differentiated Mars type body for impact velocities of 5-20 km/s, and impactor sizes of 100-400 km. We use two different rheologies for the target interior, an inviscid model ("no-stress model") and a pressure and damage-dependent strength model ("elaborated model"). To better characterize the shock pressure within the whole mantle as a function of distance from the impact site, we propose the following distribution: (1) a near field zone larger than the isobaric core that extends to 7-15 times the projectile radius into the target, where the peak shock pressure decays exponentially with increasing distance, (2) a far field zone where the pressure decays with distance following a power law. The shock pressure decreases more rapidly with distance in the near field for the elaborated model than for the no-stress model because of the influence of acoustic fluidization and damage. However to better illustrate the influence of the rheology on the shock propagation, we use the same expressions to fit the shock pressure with distance for both models. At the core-mantle boundary, CMB, the peak shock pressure jumps as the shock wave enters the core. We derived the boundary condition at CMB for the peak shock pressure. It is less sensitive to the impact velocity or the impactor size, but strongly depends on the rheology of the planet's mantle. Because of the lower shock wave velocity in the core compared to that in the mantle, the refracted shockwave propagates toward the symmetry axis of the planet, and the shock

Transfer function of multimode fiber links using an electric field propagation model: Application to Radio over Fibre Systems.

Science.gov (United States)

Gasulla, I; Capmany, J

2006-10-02

We present a closed-form expression for the evaluation of the transfer function of a multimode fiber (MMF) link based on the electric field propagation model. After validating the result we investigate the potential for broadband transmission in regions far from baseband. We find that MMFs offer the potential for broadband ROF transmission in the microwave and millimetre wave regions in short and middle reach distances.

Risk models for lower extremity injuries among short- and long distance runners : A prospective cohort study

NARCIS (Netherlands)

van Poppel, Dennis; Scholten-Peeters, Gwendolijne G.M.; van Middelkoop, Marienke; Koes, Bart W.; Verhagen, Arianne P.

2018-01-01

Background: Running injuries are very common. Risk factors for running injuries are not consistently described across studies and do not differentiate between runners of long- and short distances within one cohort. Objectives: The aim of this study is to determine risk factors for running injuries

VLF modal interference distance and nighttime D region VLF reflection height for west-east and east-west propagation paths to Fiji

Science.gov (United States)

Chand, Atishnal Elvin; Kumar, Sushil

2017-08-01

Very low frequency (VLF) signals from navigational transmitters propagate through the Earth-ionosphere waveguide formed by the Earth and the lower conducting ionosphere and show the pronounced minima during solar terminator transition between transmitter and receiver. Pronounced amplitude minima observed on 19.8 kHz (NWC transmitter) and 24.8 kHz (NLK transmitter) signals recorded at Suva (18.149°S, 178.446°E), Fiji, during 2013-2014, have been used to estimate the VLF modal interference distance (DMS) and nighttime D region VLF reflection height (hN). The NWC transmitter signal propagates mostly in west-east direction, and the NLK transmitter follows a transequatorial path propagating significantly in the east-west direction. The values of DMS calculated using midpath terminator speed are 2103 ± 172 km and 2507 ± 373 km for these paths having west-east and east-west components of VLF subionospheric propagation, respectively, which agree with previously published results and within 10% with theoretical values. We have also compared the DMS estimated using a terminator time method with that calculated using terminator speed for a particular day and found both the values to be consistent. The hN values were found to be maximum during winter of Southern Hemisphere for NWC signal and winter of Northern Hemisphere for NLK signal VLF propagation paths to Suva. The hN also shows significant day-to-day and seasonal variabilities with a maximum of about 10 km and 23 km for NWC and NLK signal propagation paths, respectively, which could be due to the atmospheric gravity waves associated with solar terminator transition, as well as meteorological factors such as strong lightnings.

Faithful reconstruction of digital holograms captured by FINCH using a Hamming window function in the Fresnel propagation.

Science.gov (United States)

Siegel, Nisan; Rosen, Joseph; Brooker, Gary

2013-10-01

Recent advances in Fresnel incoherent correlation holography (FINCH) increase the signal-to-noise ratio in hologram recording by interference of images from two diffractive lenses with focal lengths close to the image plane. Holograms requiring short reconstruction distances are created that reconstruct poorly with existing Fresnel propagation methods. Here we show a dramatic improvement in reconstructed fluorescent images when a 2D Hamming window function substituted for the disk window typically used to bound the impulse response in the Fresnel propagation. Greatly improved image contrast and quality are shown for simulated and experimentally determined FINCH holograms using a 2D Hamming window without significant loss in lateral or axial resolution.

Variation of Quench Propagation Velocities in YBCO Cables

CERN Document Server

Härö, E.; Stenvall, A.; 10.1007/s10948-015-2976-y

2015-01-01

changes during the quench. Due to the large temperature margin between the operation and the current sharing temperatures, the normal zone does not propagate with the temperature front. This means that the temperature will rise in a considerably larger volume when compared to the quenched volume. Thus, the evolution of the temperature distribution below current sharing temperature Tcs after the quench onset affects the normal zone propagation velocity in HTS more than in LTS coils. This can be seen as an acceleration of the quench propagation velocities while the quench evolves when margin to Tcs is high. In this paper we scrutinize quench propagation in a stack of YBCO cables with an in-house finite element method software which solves the heat diffusion equation. We compute the longitudinal and transverse normal zone propagation velocities at various distances from the hot spot to demonstrate the distance-variation...

An analysis of superluminal propagation becoming subluminal in highly dispersive media

Science.gov (United States)

Nanda, L.

2018-05-01

In this article the time-moments of the Poynting vector associated with an electromagnetic pulse are used to characterize the traversal time and the pulse width as the pulse propagates through highly dispersive media. The behaviour of these quantities with propagation distance is analyzed in two physical cases: Lorentz absorptive medium, and Raman gain doublet amplifying medium. It is found that the superluminal pulse propagation in these two cases with anomalous dispersion is always accompanied by pulse compression and eventually the pulse becomes subluminal with increasing distance of propagation.

A Short-Range Distance Sensor with Exceptional Linearity

Science.gov (United States)

Simmons, Steven; Youngquist, Robert

2013-01-01

A sensor has been demonstrated that can measure distance over a total range of about 300 microns to an accuracy of about 0.1 nm (resolution of about 0.01 nm). This represents an exceptionally large dynamic range of operation - over 1,000,000. The sensor is optical in nature, and requires the attachment of a mirror to the object whose distance is being measured. This work resulted from actively developing a white light interferometric system to be used to measure the depths of defects in the Space Shuttle Orbiter windows. The concept was then applied to measuring distance. The concept later expanded to include spectrometer calibration. In summary, broadband (i.e., white) light is launched into a Michelson interferometer, one mirror of which is fixed and one of which is attached to the object whose distance is to be measured. The light emerging from the interferometer has traveled one of two distances: either the distance to the fixed mirror and back, or the distance to the moving mirror and back. These two light beams mix and produce an interference pattern where some wavelengths interfere constructively and some destructively. Sending this light into a spectrometer allows this interference pattern to be analyzed, yielding the net distance difference between the two paths. The unique feature of this distance sensor is its ability to measure accurately distance over a dynamic range of more than one million, the ratio of its range (about 300 microns) to its accuracy (about 0.1 nanometer). Such a large linear operating range is rare and arises here because both amplitude and phase-matching algorithms contribute to the performance. The sensor is limited by the need to attach a mirror of some kind to the object being tracked, and by the fairly small total range, but the exceptional dynamic range should make it of interest.

K0-anti K0 mixing: Approaching its short-distance origin and heavy flavours through loops

International Nuclear Information System (INIS)

Picek, I.

1986-03-01

There have been three 'mysteries' in the history of the K-meson system: two of the pre-1964 physics as summarized by Feynman, 1) the unknown reasons for strangeness, 2) the unknown inner machinery of the K 0 -anti K 0 mixing, and the third, revealed to us in 1964, 3) CP violation. The attempts to explain these puzzles have been crucial in building the present, standard-model (SM) picture for understanding of elementary particle physics. As regards the first two points, I first want to illustrate how their study has opened the door to heavy flavours. Then I focus on some recently proposed short-distance K 0 -anti K 0 mixing mechanisms, and also remind the reader of the problem of separating short-distance (SD) from long-distance (LD) effects. As for CP violation 3), it is often considered to be just on the border of the SM. The observation of CP violation, still restricted to the K 0 meson, makes it that the K 0 -anti K 0 system is still one of the most intriguing systems in nature. The increasing body of data from heavy-quark physics have a chance to move the kaon from such a 'strange' (if not distinguished) place, and to provide a valuable test of the SM. (orig.)

Striking Distance Determined From High-Speed Videos and Measured Currents in Negative Cloud-to-Ground Lightning

Science.gov (United States)

Visacro, Silverio; Guimaraes, Miguel; Murta Vale, Maria Helena

2017-12-01

First and subsequent return strokes' striking distances (SDs) were determined for negative cloud-to-ground flashes from high-speed videos exhibiting the development of positive and negative leaders and the pre-return stroke phase of currents measured along a short tower. In order to improve the results, a new criterion was used for the initiation and propagation of the sustained upward connecting leader, consisting of a 4 A continuous current threshold. An advanced approach developed from the combined use of this criterion and a reverse propagation procedure, which considers the calculated propagation speeds of the leaders, was applied and revealed that SDs determined solely from the first video frame showing the upward leader can be significantly underestimated. An original approach was proposed for a rough estimate of first strokes' SD using solely records of current. This approach combines the 4 A criterion and a representative composite three-dimensional propagation speed of 0.34 × 106 m/s for the leaders in the last 300 m propagated distance. SDs determined under this approach showed to be consistent with those of the advanced procedure. This approach was applied to determine the SD of 17 first return strokes of negative flashes measured at MCS, covering a wide peak-current range, from 18 to 153 kA. The estimated SDs exhibit very high dispersion and reveal great differences in relation to the SDs estimated for subsequent return strokes and strokes in triggered lightning.

Distance distributions of short polypeptides recovered by fluorescence resonance energy transfer in the 10 A domain.

Science.gov (United States)

Sahoo, Harekrushna; Roccatano, Danilo; Zacharias, Martin; Nau, Werner M

2006-06-28

Fluorescence resonance energy transfer (FRET) between tryptophan (Trp) as donor and 2,3-diazabicyclo[2.2.2]oct-2-ene (Dbo) as acceptor was studied by steady-state and time-resolved fluorescence spectroscopy. The unique feature of this FRET pair is its exceptionally short Förster radius (10 A), which allows one to recover distance distributions in very short structureless peptides. The technique was applied to Trp-(GlySer)n-Dbo-NH2 peptides with n = 0-10, for which the average probe/quencher distance ranged between 8.7 and 13.7 A experimentally (in propylene glycol, analysis according to wormlike chain model) and 8.6-10.2 A theoretically (for n = 0-6, GROMOS96 molecular dynamics simulations). The larger FRET efficiency in steady-state compared to time-resolved fluorescence experiments was attributed to a static quenching component, suggesting that a small but significant part (ca. 10%) of the conformations are already in van der Waals contact when excitation occurs.

Coulomb systems distorted at short distances in atomic and nuclear physics

International Nuclear Information System (INIS)

Popov, V.S.

1987-01-01

In systems bound by the Coulomb interaction distorted at short distances there may appear, under certain conditions, a rearrangment of atomic spectrum (or the Zel'dovich effect). Specific features of this effect are discussed for states with an arbitrary angular momentum l (both with and without the absorption). The equation is studied which connects nuclear level shifts with the low-energy scattering parameters a l , r l . The conditions have been found under which the rearrangement of spectrum is replaced by oscillations of atomic levels. The Coulomb renormalization of scattering lengths and that of effective ranges is discussed. Some manifestations of the Zel'dovich effect in the physics of hadronic atoms and mesomolecules are considered

Propagation and stability characteristics of a 500-m-long laser-based fiducial line for high-precision alignment of long-distance linear accelerators.

Science.gov (United States)

Suwada, Tsuyoshi; Satoh, Masanori; Telada, Souichi; Minoshima, Kaoru

2013-09-01

A laser-based alignment system with a He-Ne laser has been newly developed in order to precisely align accelerator units at the KEKB injector linac. The laser beam was first implemented as a 500-m-long fiducial straight line for alignment measurements. We experimentally investigated the propagation and stability characteristics of the laser beam passing through laser pipes in vacuum. The pointing stability at the last fiducial point was successfully obtained with the transverse displacements of ±40 μm level in one standard deviation by applying a feedback control. This pointing stability corresponds to an angle of ±0.08 μrad. This report contains a detailed description of the experimental investigation for the propagation and stability characteristics of the laser beam in the laser-based alignment system for long-distance linear accelerators.

Propagation of 1-THz bandwidth electrical pulses on high Tc superconducting transmission lines

International Nuclear Information System (INIS)

Nuss, M.C.; Mankiewich, P.M.; Howard, R.E.; Harvey, T.E.; Brandle, C.D.; Straugh, B.L.; Smith, P.R.

1989-01-01

The new high temperature superconductors have triggered enormous interest not only because of the unique physics involved but also because of their technical potentials, such as the promise for propagation of extremely short electrical pulses. Superconducting band caps of --20TH z are predicted assuming BCS theory for the superconductor, making lossless propagation of electrical pulses as short as 50 fs possible. Despite microwave measurements at low frequencies of several gigahertz first studies at higher frequencies by Dykaar et al have shown distortion-free propagation of 100-GHz electrical pulses on YBa 2 Cu 3 O 3 (YBCO) lines for --5-mm propagation distance. Results were also reported for aluminum coplanar lines and a YBCO ground plane. The authors report on the propagation of 1-ps electrical pulses (1-THz bandwidth) on YBCO coplanar transmission lines defined on lanthanum gallate (LaGaO 3 ) as a substrate. On LaGaO 3 , YBCO grows highly oriented as on SrTiO 3 . However, unlike SrTiO 3 , LaGaO 3 has a much lower dielectric constant and small losses in the terahertz frequency range. Electrical pulses of --750-fs duration are generated in a radiation-damaged silicon-on-sapphire photoconductive switch integrated into a 20-μm coplanar stripline with 10-μm spacing and excited with 100-fs optical pulses from a CPM laser. An μ1-THz bandwidth electrical contact is made to the YBCO coplanar stripline defined on LaGaO 3 using a flip-chip geometry. They find that electrical pulses broaden only from 750 fs to 1 ps with little loss in amplitude on traveling through their flip-chip input and propagated electrical pulses are probed by electooptic sampling in two small LiTaO 3 crystals separated by 3 mm

Short binary convolutional codes with maximal free distance for rates 2/3 and 3/4

DEFF Research Database (Denmark)

Paaske, Erik

1974-01-01

. Farther, the search among the remaining codes is started in a subset in which we expect the possibility of finding codes with large values ofd_{free}to be good. A number of short, optimum (in the sense of maximizingd_{free}), rate-2/3 and 3/4 codes found by the search procedure are listed.......A search procedure is developed to find good short binary(N,N - 1)convolutional codes. It uses simple rules to discard from the complete ensemble of codes a large fraction whose free distanced_{free}either cannot achieve the maximum value or is equal tod_{free}of some code in the remaining set...

High energy colliders as black hole factories: The end of short distance physics

International Nuclear Information System (INIS)

Giddings, Steven B.; Thomas, Scott

2002-01-01

If the fundamental Planck scale is of order of a TeV, as is the case in some extra-dimension scenarios, future hadron colliders such as the CERN Large Hadron Collider will be black hole factories. The nonperturbative process of black hole formation and decay by Hawking evaporation gives rise to spectacular events with up to many dozens of relatively hard jets and leptons with a characteristic ratio of hadronic to leptonic activity of roughly 5:1. The total transverse energy of such events is typically a sizable fraction of the beam energy. Perturbative hard scattering processes at energies well above the Planck scale are cloaked behind a horizon, thus limiting the ability to probe short distances. The high energy black hole cross section grows with energy at a rate determined by the dimensionality and geometry of the extra dimensions. This dependence therefore probes the extra dimensions at distances larger than the Planck scale

Action potential propagation: ion current or intramembrane electric field?

Science.gov (United States)

Martí, Albert; Pérez, Juan J; Madrenas, Jordi

2018-01-01

The established action potential propagation mechanisms do not satisfactorily explain propagation on myelinated axons given the current knowledge of biological channels and membranes. The flow across ion channels presents two possible effects: the electric potential variations across the lipid bilayers (action potential) and the propagation of an electric field through the membrane inner part. The proposed mechanism is based on intra-membrane electric field propagation, this propagation can explain the action potential saltatory propagation and its constant delay independent of distance between Ranvier nodes in myelinated axons.

Tropospheric radiowave propagation beyond the horizon

CERN Document Server

Du Castel, François

1966-01-01

Tropospheric Radiowave Propagation Beyond the Horizon deals with developments concerning the tropospheric propagation of ultra-short radio waves beyond the horizon, with emphasis on the relationship between the theoretical and the experimental. Topics covered include the general conditions of propagation in the troposphere; general characteristics of propagation beyond the horizon; and attenuation in propagation. This volume is comprised of six chapters and begins with a brief historical look at the various stages that have brought the technique of transhorizon links to its state of developmen

Experimental simulations of beam propagation over large distances in a compact linear Paul trap

International Nuclear Information System (INIS)

Gilson, Erik P.; Chung, Moses; Davidson, Ronald C.; Dorf, Mikhail; Efthimion, Philip C.; Majeski, Richard

2006-01-01

The Paul Trap Simulator Experiment (PTSX) is a compact laboratory experiment that places the physicist in the frame of reference of a long, charged-particle bunch coasting through a kilometers-long magnetic alternating-gradient (AG) transport system. The transverse dynamics of particles in both systems are described by similar equations, including nonlinear space-charge effects. The time-dependent voltages applied to the PTSX quadrupole electrodes are equivalent to the axially oscillating magnetic fields applied in the AG system. Experiments concerning the quiescent propagation of intense beams over large distances can then be performed in a compact and flexible facility. An understanding and characterization of the conditions required for quiescent beam transport, minimum halo particle generation, and precise beam compression and manipulation techniques, are essential, as accelerators and transport systems demand that ever-increasing amounts of space charge be transported. Application areas include ion-beam-driven high energy density physics, high energy and nuclear physics accelerator systems, etc. One-component cesium plasmas have been trapped in PTSX that correspond to normalized beam intensities, s=ω p 2 (0)/2ω q 2 , up to 80% of the space-charge limit where self-electric forces balance the applied focusing force. Here, ω p (0)=[n b (0)e b 2 /m b ε 0 ] 1/2 is the on-axis plasma frequency, and ω q is the smooth-focusing frequency associated with the applied focusing field. Plasmas in PTSX with values of s that are 20% of the limit have been trapped for times corresponding to equivalent beam propagation over 10 km. Results are presented for experiments in which the amplitude of the quadrupole focusing lattice is modified as a function of time. It is found that instantaneous changes in lattice amplitude can be detrimental to transverse confinement of the charge bunch

Experimental simulations of beam propagation over large distances in a compact linear Paul trapa)

Science.gov (United States)

Gilson, Erik P.; Chung, Moses; Davidson, Ronald C.; Dorf, Mikhail; Efthimion, Philip C.; Majeski, Richard

2006-05-01

The Paul Trap Simulator Experiment (PTSX) is a compact laboratory experiment that places the physicist in the frame of reference of a long, charged-particle bunch coasting through a kilometers-long magnetic alternating-gradient (AG) transport system. The transverse dynamics of particles in both systems are described by similar equations, including nonlinear space-charge effects. The time-dependent voltages applied to the PTSX quadrupole electrodes are equivalent to the axially oscillating magnetic fields applied in the AG system. Experiments concerning the quiescent propagation of intense beams over large distances can then be performed in a compact and flexible facility. An understanding and characterization of the conditions required for quiescent beam transport, minimum halo particle generation, and precise beam compression and manipulation techniques, are essential, as accelerators and transport systems demand that ever-increasing amounts of space charge be transported. Application areas include ion-beam-driven high energy density physics, high energy and nuclear physics accelerator systems, etc. One-component cesium plasmas have been trapped in PTSX that correspond to normalized beam intensities, ŝ=ωp2(0)/2ωq2, up to 80% of the space-charge limit where self-electric forces balance the applied focusing force. Here, ωp(0)=[nb(0)eb2/mbɛ0]1/2 is the on-axis plasma frequency, and ωq is the smooth-focusing frequency associated with the applied focusing field. Plasmas in PTSX with values of ŝ that are 20% of the limit have been trapped for times corresponding to equivalent beam propagation over 10km. Results are presented for experiments in which the amplitude of the quadrupole focusing lattice is modified as a function of time. It is found that instantaneous changes in lattice amplitude can be detrimental to transverse confinement of the charge bunch.

Graviton propagator from background-independent quantum gravity.

Science.gov (United States)

Rovelli, Carlo

2006-10-13

We study the graviton propagator in Euclidean loop quantum gravity. We use spin foam, boundary-amplitude, and group-field-theory techniques. We compute a component of the propagator to first order, under some approximations, obtaining the correct large-distance behavior. This indicates a way for deriving conventional spacetime quantities from a background-independent theory.

Modification of quantum mechanics at short distances: a simple approach to confinement and asymptotic freedom. [Planck constant

Energy Technology Data Exchange (ETDEWEB)

Mahajan, S.M.; Qadir, A.; Valanju, P.M.

1979-07-01

To make quantum mechanics a suitable description of short-distance (less than or equal to 10/sup -13/ cm) physics, a spatial variation of Planck's constant anti h is introduced. It is shown that the new theory implies asymptotic freedom and quark confinement in a simple way. 10 references.

Plume dispersion and deposition processes of tracer gas and aerosols in short-distance experiments

International Nuclear Information System (INIS)

Taeschner, M.; Bunnenberg, C.

1988-01-01

Data used in this paper were extracted from field experiments carried out in France and Canada to study the pathway of elementary tritium after possible emissions from future fusion reactors and from short-range experiments with nutrient aerosols performed in a German forest in view of a therapy of damaged coniferous trees by foliar nutrition. Comparisons of dispersion parameters evaluated from the tritium field experiments show that in the case of the 30-min release the variations of the wind directions represent the dominant mechanism of lateral plume dispersion under unstable weather conditions. This corresponds with the observation that for the short 2-min emission the plume remains more concentrated during propagation, and the small lateral dispersion parameters typical for stable conditions have to be applied. The investigations on the dispersion of aerosol plumes into a forest boundary layer show that the Gaussian plume model can be modified by a windspeed factor to be valid for predictions on aerosol concentrations and depositions even in a structured topography like a forest

The short distance contribution to the Bs → γγ decay in the SM and MSSM

International Nuclear Information System (INIS)

Devidze, G.G.

2000-06-01

The complete calculation of the short distance contributions to the B s → γγ decay in the SM and MSSM are presented. The branching ratio and relative part of CP-even state of final photons are calculated. The branching ratio and relative part of CP-even state of final photons in the MSSM maybe significantly larger than the standard model estimate. (author)

Communication with diode laser: short distance line of sight communication using fiber optics

International Nuclear Information System (INIS)

Mirza, A.H.

1999-01-01

The objective of this project is to carry audio signal from transmitting station to a short distance receiving station along line of sight and also communication through fiber optics is performed, using diode laser light as carrier. In this project optical communication system, modulation techniques, basics of laser and causes of using diode laser are discussed briefly. Transmitter circuit and receiver circuit are fully described. Communication was performed using pulse width modulation technique. Optical fiber communication have many advantages over other type of conventional communication techniques. This report contains the description of optical fiber communication and compared with other communication systems. (author)

The Comparison of Propagation Model for Terrestrial Trunked Radio (TETRA

Directory of Open Access Journals (Sweden)

Ayu Kartika R

2013-12-01

Full Text Available A system of digital radio Terrestrial Trunked Radio (TETRA is designed for communication which need specialility, better privacy, better quality of audio with speed transmission data and access capacity to the internet and telephone network. TETRA system of TMO and DMO operation mode which has wide coverage and reliable than the interference so that the TETRA planning needs a propagation model which corresponding with environment. Therefore, this research compare a pathloss value of calculation of propagation model such as Free Space Loss, Wickson, Bacon, CEPT SE21, Ericsson (9999, ITU-R SM 2028 and Okumura Hata based on the environment are clutter urban, sub urban dan rural. The calculation of pathloss provide that Bacon propagation model is an corresponding model for DMO operation mode with a frequency of 380 MHz, height handhelds 1.5 m and 2 m with pathloss value of 76.82 dB at a distance of 100 m and 113.63 dB at a distance of 1 km while the 400 MHz frequency pathloss value of 77.08 dB at a distance of 100 m and 113.6 dB at a distance of 1 km. The propagation model which corresponding to the TMO operation mode with a frequency of 400 MHz distance of 1 km, the transmitter antenna height (hb 30 m and receiver antenna height (hm 1.5 m is a model of Ericsson (9999 on urban clutter with pathloss value of 96.4 dB, the model ITU-R SM2028 in suburban clutter with a pathloss value of 101.13 dB, and the model ITU-R SM2028 on rural clutter with pathloss value of 83.59 dB. Keywords: TETRA, propagation model, urban, suburban, rural

Short-distance tumour irradiation system for interstitial and intracavitary use, with preselectable isodose programme

International Nuclear Information System (INIS)

Sauerwein, K.

1976-01-01

The report describes a new development of the short distance irradiation system for interstitial and intracavitary use, GammaMedsup((R)). First, the main data of GammaMed I are summarized. Next, the development in cooperation with M. Busch of the Essen University Radiation Clinic of GammaMed II is outlined. The new unit includes an Ir-192 point source emitter which scans the applicator probe in accordance with a computer program which can be preselected at random. In this way, all isodose distributions can be achieved which are needed in practice. (orig./HP) [de

Physiological responses at short distances from a parametric speaker

Directory of Open Access Journals (Sweden)

Lee Soomin

2012-06-01

Full Text Available Abstract In recent years, parametric speakers have been used in various circumstances. In our previous studies, we verified that the physiological burden of the sound of parametric speaker set at 2.6 m from the subjects was lower than that of the general speaker. However, nothing has yet been demonstrated about the effects of the sound of a parametric speaker at the shorter distance between parametric speakers the human body. Therefore, we studied this effect on physiological functions and task performance. Nine male subjects participated in this study. They completed three consecutive sessions: a 20-minute quiet period as a baseline, a 30-minute mental task period with general speakers or parametric speakers, and a 20-minute recovery period. We measured electrocardiogram (ECG photoplethysmogram (PTG, electroencephalogram (EEG, systolic and diastolic blood pressure. Four experiments, one with a speaker condition (general speaker and parametric speaker, the other with a distance condition (0.3 m and 1.0 m, were conducted respectively at the same time of day on separate days. To examine the effects of the speaker and distance, three-way repeated measures ANOVA (speaker factor x distance factor x time factor were conducted. In conclusion, we found that the physiological responses were not significantly different between the speaker condition and the distance condition. Meanwhile, it was shown that the physiological burdens increased with progress in time independently of speaker condition and distance condition. In summary, the effects of the parametric speaker at the 2.6 m distance were not obtained at the distance of 1 m or less.

Temporal Talbot effect in propagation of attosecond electron waves

International Nuclear Information System (INIS)

Varro, S.

2010-01-01

Complete text of publication follows. The rapid development in extreme strong-field and extreme short-pulse laser physics provide us with many potentials to explore the dynamics of fundamental processes taking place in light-matter interactions and in propagation of electromagnetic or matter waves. The present paper discusses the propagation of above-threshold electron waves generated by (not necessary ultra-short) strong laser fields. Recently we have shown that - in analogy with the formation of attosecond light pulses by interference of high-order harmonics - the wave components of photoelectrons are naturally assembled in attosecond spikes, through the Fourier synthesis of these de Broglie waves. We would like to emphasize that the proposed scheme does not presupposes an a priori ultrashort excitation. Owing to the inherent dispersion of electron waves even in vacuum, the clean attosecond structure (emanating perpendicularly from a metal target surface) is gradually spoiled due to destructive interference. Fortunately the collapsed fine structure recovers itself at certain distances from the source within well-defined 'revival layers'. This is a temporal analogon of the optical Talbot effect representing the self-imaging of a grating, which is illuminated by stationary plane waves, in the near field. The 'collaps bands' and the 'revival layers' introduced in ref. 3 have been found merely on the basis of some attosecond layers turned out to show certain regularities. In the meantime we have derived approximate analytic formulae for the propagation characteristics, with the help of which we can keep track of the locations of the 'collaps bands' and the 'revival layers' on a larger scale. We shall report on these semiclassical results, and also discuss their possible connection with the recently found entropy remnants in multiphoton Compton scattering by electronic wave packets. Acknowledgement. This work has been supported by the Hungarian National Scientific

Propagation Velocity of Solid Earth Tides

Science.gov (United States)

Pathak, S.

2017-12-01

One of the significant considerations in most of the geodetic investigations is to take into account the outcome of Solid Earth tides on the location and its consequent impact on the time series of coordinates. In this research work, the propagation velocity resulting from the Solid Earth tides between the Indian stations is computed. Mean daily coordinates for the stations have been computed by applying static precise point positioning technique for a day. The computed coordinates are used as an input for computing the tidal displacements at the stations by Gravity method along three directions at 1-minute interval for 24 hours. Further the baseline distances are computed between four Indian stations. Computation of the propagation velocity for Solid Earth tides can be done by the virtue of study of the concurrent effect of it in-between the stations of identified baseline distance along with the time consumed by the tides for reaching from one station to another. The propagation velocity helps in distinguishing the impact at any station if the consequence at a known station for a specific time-period is known. Thus, with the knowledge of propagation velocity, the spatial and temporal effects of solid earth tides can be estimated with respect to a known station. As theoretically explained, the tides generated are due to the position of celestial bodies rotating about Earth. So the need of study is to observe the correlation of propagation velocity with the rotation speed of the Earth. The propagation velocity of Solid Earth tides comes out to be in the range of 440-470 m/s. This velocity comes out to be in a good agreement with the Earth's rotation speed.

Testing gravitational parity violation with coincident gravitational waves and short gamma-ray bursts

International Nuclear Information System (INIS)

Yunes, Nicolas; O'Shaughnessy, Richard; Owen, Benjamin J.; Alexander, Stephon

2010-01-01

Gravitational parity violation is a possibility motivated by particle physics, string theory, and loop quantum gravity. One effect of it is amplitude birefringence of gravitational waves, whereby left and right circularly polarized waves propagate at the same speed but with different amplitude evolution. Here we propose a test of this effect through coincident observations of gravitational waves and short gamma-ray bursts from binary mergers involving neutron stars. Such gravitational waves are highly left or right circularly polarized due to the geometry of the merger. Using localization information from the gamma-ray burst, ground-based gravitational wave detectors can measure the distance to the source with reasonable accuracy. An electromagnetic determination of the redshift from an afterglow or host galaxy yields an independent measure of this distance. Gravitational parity violation would manifest itself as a discrepancy between these two distance measurements. We exemplify such a test by considering one specific effective theory that leads to such gravitational parity violation, Chern-Simons gravity. We show that the advanced LIGO-Virgo network and all-sky gamma-ray telescopes can be sensitive to the propagating sector of Chern-Simons gravitational parity violation to a level roughly 2 orders of magnitude better than current stationary constraints from the LAGEOS satellites.

Investigation on relationship between epicentral distance and growth curve of initial P-wave propagating in local heterogeneous media for earthquake early warning system

Science.gov (United States)

Okamoto, Kyosuke; Tsuno, Seiji

2015-10-01

In the earthquake early warning (EEW) system, the epicenter location and magnitude of earthquakes are estimated using the amplitude growth rate of initial P-waves. It has been empirically pointed out that the growth rate becomes smaller as epicentral distance becomes far regardless of the magnitude of earthquakes. So, the epicentral distance can be estimated from the growth rate using this empirical relationship. However, the growth rates calculated from different earthquakes at the same epicentral distance mark considerably different values from each other. Sometimes the growth rates of earthquakes having the same epicentral distance vary by 104 times. Qualitatively, it has been considered that the gap in the growth rates is due to differences in the local heterogeneities that the P-waves propagate through. In this study, we demonstrate theoretically how local heterogeneities in the subsurface disturb the relationship between the growth rate and the epicentral distance. Firstly, we calculate seismic scattered waves in a heterogeneous medium. First-ordered PP, PS, SP, and SS scatterings are considered. The correlation distance of the heterogeneities and fractional fluctuation of elastic parameters control the heterogeneous conditions for the calculation. From the synthesized waves, the growth rate of the initial P-wave is obtained. As a result, we find that a parameter (in this study, correlation distance) controlling heterogeneities plays a key role in the magnitude of the fluctuation of the growth rate. Then, we calculate the regional correlation distances in Japan that can account for the fluctuation of the growth rate of real earthquakes from 1997 to 2011 observed by K-NET and KiK-net. As a result, the spatial distribution of the correlation distance shows locality. So, it is revealed that the growth rates fluctuate according to the locality. When this local fluctuation is taken into account, the accuracy of the estimation of epicentral distances from initial P

Role of the Short Distance Order in Glass Reactivity

Directory of Open Access Journals (Sweden)

María Vallet-Regi

2018-03-01

Full Text Available In 2005, our group described for the first time the structural characterization at the atomic scale of bioactive glasses and the influence of the glasses’ nanostructure in their reactivity in simulated body fluids. In that study, two bioactive sol-gel glasses with composition 80%SiO2–20%CaO and 80%SiO2–17%CaO–3%P2O5 (in mol-% were characterized by High-Resolution Transmission Electron Microscopy (HRTEM. Such characterization revealed unknown features of the glasses’ structure at the local scale that allowed the understanding of their different in vitro behaviors as a consequence of the presence or absence of P2O5. Since then, the nanostructure of numerous bioactive glasses, including melt-prepared, sol-gel derived, and mesoporous glasses, was investigated by HRTEM, Nuclear Magnetic Resonance (NMR spectroscopy, Molecular Dynamics (MD simulations, and other experimental techniques. These studies have shown that although glasses are amorphous solids, a certain type of short distance order, which greatly influences the in vitro and in vivo reactivity, is always present. This paper reviews the most significant advances in the understanding of bioactive glasses that took place in the last years as a result of the growing knowledge of the glasses’ nanostructure.

Role of the Short Distance Order in Glass Reactivity

Science.gov (United States)

2018-01-01

In 2005, our group described for the first time the structural characterization at the atomic scale of bioactive glasses and the influence of the glasses’ nanostructure in their reactivity in simulated body fluids. In that study, two bioactive sol-gel glasses with composition 80%SiO2–20%CaO and 80%SiO2–17%CaO–3%P2O5 (in mol-%) were characterized by High-Resolution Transmission Electron Microscopy (HRTEM). Such characterization revealed unknown features of the glasses’ structure at the local scale that allowed the understanding of their different in vitro behaviors as a consequence of the presence or absence of P2O5. Since then, the nanostructure of numerous bioactive glasses, including melt-prepared, sol-gel derived, and mesoporous glasses, was investigated by HRTEM, Nuclear Magnetic Resonance (NMR) spectroscopy, Molecular Dynamics (MD) simulations, and other experimental techniques. These studies have shown that although glasses are amorphous solids, a certain type of short distance order, which greatly influences the in vitro and in vivo reactivity, is always present. This paper reviews the most significant advances in the understanding of bioactive glasses that took place in the last years as a result of the growing knowledge of the glasses’ nanostructure. PMID:29534481

Multi-directional emission and detection of spin waves propagating in yttrium iron garnet with wavelengths down to about 100 nm

Science.gov (United States)

Maendl, Stefan; Grundler, Dirk

2018-05-01

We performed broadband spin-wave spectroscopy on 200 nm thick yttrium iron garnet containing arrays of partially embedded magnetic nanodisks. Using integrated coplanar waveguides (CPWs), we studied the excitation and transmission of spin waves depending on the presence of nanomagnet arrays of different lateral extensions. By means of the grating coupler effect, we excited spin waves propagating in multiple lateral directions with wavelengths down to 111 nm. They exhibited group velocities of up to 1 km/s. Detection of such short-wavelength spin waves was possible only in symmetrically designed emitter/detector configurations, not with a bare CPW. We report spin waves propagating between grating couplers under oblique angles exhibiting a wave vector component parallel to the CPW. The effective propagation distance amounted to about 80 μm. Such transmission signals were not addressed before and substantiate the versatility of the grating coupler effect for implementing nanomagnonic circuits.

Propagation of rotational Risley-prism-array-based Gaussian beams in turbulent atmosphere

Science.gov (United States)

Chen, Feng; Ma, Haotong; Dong, Li; Ren, Ge; Qi, Bo; Tan, Yufeng

2018-03-01

Limited by the size and weight of prism and optical assembling, Rotational Risley-prism-array system is a simple but effective way to realize high power and superior beam quality of deflecting laser output. In this paper, the propagation of the rotational Risley-prism-array-based Gaussian beam array in atmospheric turbulence is studied in detail. An analytical expression for the average intensity distribution at the receiving plane is derived based on nonparaxial ray tracing method and extended Huygens-Fresnel principle. Power in the diffraction-limited bucket is chosen to evaluate beam quality. The effect of deviation angle, propagation distance and intensity of turbulence on beam quality is studied in detail by quantitative simulation. It reveals that with the propagation distance increasing, the intensity distribution gradually evolves from multiple-petal-like shape into the pattern that contains one main-lobe in the center with multiple side-lobes in weak turbulence. The beam quality of rotational Risley-prism-array-based Gaussian beam array with lower deviation angle is better than its counterpart with higher deviation angle when propagating in weak and medium turbulent (i.e. Cn2 beam quality of higher deviation angle arrays degrades faster as the intensity of turbulence gets stronger. In the case of propagating in strong turbulence, the long propagation distance (i.e. z > 10km ) and deviation angle have no influence on beam quality.

Nonlinear propagation of vector extremely short pulses in a medium of symmetric and asymmetric molecules

Energy Technology Data Exchange (ETDEWEB)

Sazonov, S. V., E-mail: sazonov.sergey@gmail.com [National Research Centre “Kurchatov Institute,” (Russian Federation); Ustinov, N. V., E-mail: n-ustinov@mail.ru [Moscow State University of Railways, Kaliningrad Branch (Russian Federation)

2017-02-15

The nonlinear propagation of extremely short electromagnetic pulses in a medium of symmetric and asymmetric molecules placed in static magnetic and electric fields is theoretically studied. Asymmetric molecules differ in that they have nonzero permanent dipole moments in stationary quantum states. A system of wave equations is derived for the ordinary and extraordinary components of pulses. It is shown that this system can be reduced in some cases to a system of coupled Ostrovsky equations and to the equation intagrable by the method for an inverse scattering transformation, including the vector version of the Ostrovsky–Vakhnenko equation. Different types of solutions of this system are considered. Only solutions representing the superposition of periodic solutions are single-valued, whereas soliton and breather solutions are multivalued.

Some models of propagation of extremely short electromagnetic pulses in a nonlinear medium

International Nuclear Information System (INIS)

Maimistov, Andrei I

2000-01-01

Some cases of model media considered in this paper allow analytical solutions to nonlinear wave equations to be found and the time dependence of the electric field strength to be determined in the explicit form for arbitrarily short electromagnetic pulses. Our analysis does not employ any assumptions concerning a harmonic carrier wave or the variation rate of the field in such pulses. The class of models considered includes two-level resonance and quasi-resonance systems. Nonresonance media are analysed in terms of models of anharmonic oscillators - the Duffing and Lorentz models. In most cases, only particular solutions describing the stationary propagation of a video pulse (a unipolar transient of the electric field or a pulse including a small number of oscillations of the electric field around zero) can be found. These solutions correspond to sufficiently strong electromagnetic fields when the dispersion inherent in the medium is suppressed by nonlinear processes. (invited paper)

On low-frequency whistler propagation in ionosphere

International Nuclear Information System (INIS)

Mazur, V.A.

1988-01-01

The propagation along the Earth surface of an electromagnetic wave with frequency below the ion gyrofrequency is theoretically investigated. In Hall layer of the ionosphere this wave is the whistler mode. It is shown that - contrary to previous works - Ohmic dissipation makes impossible the long-distance propagation of low-frequency whistlers. A many-layer model of the medium is used. The geomagnetic field is considered inclined. The eigen modes and evolution of the initial perturbation are considered

Quantum dynamics via a time propagator in Wigner's phase space

DEFF Research Database (Denmark)

Grønager, Michael; Henriksen, Niels Engholm

1995-01-01

We derive an expression for a short-time phase space propagator. We use it in a new propagation scheme and demonstrate that it works for a Morse potential. The propagation scheme is used to propagate classical distributions which do not obey the Heisenberg uncertainty principle. It is shown that ...... as a part of the sampling function. ©1995 American Institute of Physics....

Can Neural Activity Propagate by Endogenous Electrical Field?

Science.gov (United States)

Qiu, Chen; Shivacharan, Rajat S.; Zhang, Mingming

2015-01-01

It is widely accepted that synaptic transmissions and gap junctions are the major governing mechanisms for signal traveling in the neural system. Yet, a group of neural waves, either physiological or pathological, share the same speed of ∼0.1 m/s without synaptic transmission or gap junctions, and this speed is not consistent with axonal conduction or ionic diffusion. The only explanation left is an electrical field effect. We tested the hypothesis that endogenous electric fields are sufficient to explain the propagation with in silico and in vitro experiments. Simulation results show that field effects alone can indeed mediate propagation across layers of neurons with speeds of 0.12 ± 0.09 m/s with pathological kinetics, and 0.11 ± 0.03 m/s with physiologic kinetics, both generating weak field amplitudes of ∼2–6 mV/mm. Further, the model predicted that propagation speed values are inversely proportional to the cell-to-cell distances, but do not significantly change with extracellular resistivity, membrane capacitance, or membrane resistance. In vitro recordings in mice hippocampi produced similar speeds (0.10 ± 0.03 m/s) and field amplitudes (2.5–5 mV/mm), and by applying a blocking field, the propagation speed was greatly reduced. Finally, osmolarity experiments confirmed the model's prediction that cell-to-cell distance inversely affects propagation speed. Together, these results show that despite their weak amplitude, electric fields can be solely responsible for spike propagation at ∼0.1 m/s. This phenomenon could be important to explain the slow propagation of epileptic activity and other normal propagations at similar speeds. SIGNIFICANCE STATEMENT Neural activity (waves or spikes) can propagate using well documented mechanisms such as synaptic transmission, gap junctions, or diffusion. However, the purpose of this paper is to provide an explanation for experimental data showing that neural signals can propagate by means other than synaptic

Age and gender interactions in short distance triathlon performance.

Science.gov (United States)

Etter, Franziska; Knechtle, Beat; Bukowski, Arkadiusz; Rüst, Christoph Alexander; Rosemann, Thomas; Lepers, Romuald

2013-01-01

This study investigated the participation and performance trends as well as the age and gender interaction at the Olympic distance 'Zürich Triathlon' (1.5 km swim, 40 km cycle and 10 km run) from 2000 to 2010 in 7,939 total finishers (1,666 females and 6,273 males). Female triathletes aged from 40 to 54 years significantly (P distance triathlon performance increased after the age of 35 years, which appeared earlier compared to long distance triathlon as suggested by previous studies. Future investigations should compare gender difference in performance for different endurance events across age to confirm a possible effect of exercise duration on gender difference with advancing age.

Complex characterization of short-pulse propagation through InAs/InP quantum-dash optical amplifiers: From the quasi-linear to the two-photon-dominated regime

DEFF Research Database (Denmark)

Capua, Amir; Saal, Abigael; Karni, Ouri

2012-01-01

We describe direct measurements at a high temporal resolution of the changes experienced by the phase and amplitude of an ultra-short pulse upon propagation through an inhomogenously broadened semiconductor nanostructured optical gain medium. Using a cross frequency-resolved optical gating techni...

ON SUN-TO-EARTH PROPAGATION OF CORONAL MASS EJECTIONS

International Nuclear Information System (INIS)

Liu, Ying D.; Luhmann, Janet G.; Möstl, Christian; Bale, Stuart D.; Lin, Robert P.; Lugaz, Noé; Davies, Jackie A.

2013-01-01

We investigate how coronal mass ejections (CMEs) propagate through, and interact with, the inner heliosphere between the Sun and Earth, a key question in CME research and space weather forecasting. CME Sun-to-Earth kinematics are constrained by combining wide-angle heliospheric imaging observations, interplanetary radio type II bursts, and in situ measurements from multiple vantage points. We select three events for this study, the 2012 January 19, 23, and March 7 CMEs. Different from previous event studies, this work attempts to create a general picture for CME Sun-to-Earth propagation and compare different techniques for determining CME interplanetary kinematics. Key results are obtained concerning CME Sun-to-Earth propagation: (1) the Sun-to-Earth propagation of fast CMEs can be approximately formulated into three phases: an impulsive acceleration, then a rapid deceleration, and finally a nearly constant speed propagation (or gradual deceleration); (2) the CMEs studied here are still accelerating even after the flare maximum, so energy must be continuously fed into the CME even after the time of the maximum heating and radiation has elapsed in the corona; (3) the rapid deceleration, presumably due to interactions with the ambient medium, mainly occurs over a relatively short timescale following the acceleration phase; and (4) CME-CME interactions seem a common phenomenon close to solar maximum. Our comparison between different techniques (and data sets) has important implications for CME observations and their interpretations: (1) for the current cases, triangulation assuming a compact CME geometry is more reliable than triangulation assuming a spherical front attached to the Sun for distances below 50-70 solar radii from the Sun, but beyond about 100 solar radii we would trust the latter more; (2) a proper treatment of CME geometry must be performed in determining CME Sun-to-Earth kinematics, especially when the CME propagation direction is far away from the

Unirradiated cladding rip-propagation tests

International Nuclear Information System (INIS)

Hu, W.L.; Hunter, C.W.

1981-04-01

The size of cladding rips which develop when a fuel pin fails can affect the subassembly cooling and determine how rapidly fuel escapes from the pin. The object of the Cladding Rip Propagation Test (CRPT) was to quantify the failure development of cladding so that a more realistic fuel pin failure modeling may be performed. The test results for unirradiated 20% CS 316 stainless steel cladding show significantly different rip propagation behavior at different temperatures. At room temperature, the rip growth is stable as the rip extension increases monotonically with the applied deformation. At 500 0 C, the rip propagation becomes unstable after a short period of stable rip propagation. The rapid propagation rate is approximately 200 m/s, and the critical rip length is 9 mm. At test temperatures above 850 0 C, the cladding exhibits very high failure resistances, and failure occurs by multiple cracking at high cladding deformation. 13 figures

Spatial-temporal dynamics of broadband terahertz Bessel beam propagation

International Nuclear Information System (INIS)

Semenova, V A; Kulya, M S; Bespalov, V G

2016-01-01

The unique properties of narrowband and broadband terahertz Bessel beams have led to a number of their applications in different fields, for example, for the depth of focusing and resolution enhancement in terahertz imaging. However, broadband terahertz Bessel beams can probably be also used for the diffraction minimization in the short-range broadband terahertz communications. For this purpose, the study of spatial-temporal dynamics of the broadband terahertz Bessel beams is needed. Here we present a simulation-based study of the propagating in non-dispersive medium broadband Bessel beams generated by a conical axicon lens. The algorithm based on scalar diffraction theory was used to obtain the spatial amplitude and phase distributions of the Bessel beam in the frequency range from 0.1 to 3 THz at the distances 10-200 mm from the axicon. Bessel beam field is studied for the different spectral components of the initial pulse. The simulation results show that for the given parameters of the axicon lens one can obtain the Gauss-Bessel beam generation in the spectral range from 0.1 to 3 THz. The length of non-diffraction propagation for a different spectral components was measured, and it was shown that for all spectral components of the initial pulse this length is about 130 mm. (paper)

Short-distance matrix elements for $D$-meson mixing for 2+1 lattice QCD

Energy Technology Data Exchange (ETDEWEB)

Chang, Chia Cheng [Univ. of Illinois, Champaign, IL (United States)

2015-01-01

We study the short-distance hadronic matrix elements for D-meson mixing with partially quenched N_f = 2+1 lattice QCD. We use a large set of the MIMD Lattice Computation Collaboration's gauge configurations with a² tadpole-improved staggered sea quarks and tadpole-improved Lüscher-Weisz gluons. We use the a² tadpole-improved action for valence light quarks and the Sheikoleslami-Wohlert action with the Fermilab interpretation for the valence charm quark. Our calculation covers the complete set of five operators needed to constrain new physics models for D-meson mixing. We match our matrix elements to the MS-NDR scheme evaluated at 3 GeV. We report values for the Beneke-Buchalla-Greub-Lenz-Nierste choice of evanescent operators.

Thermal propagation and stability in superconducting films

International Nuclear Information System (INIS)

Gray, K.E.; Kampwirth, R.T.; Zasadzinski, J.F.; Ducharme, S.P.

1983-01-01

Thermal propagation and stable hot spots (normal domains) are studied in various high Tsub(c) superconducting films (Nb 3 Sn, Nb, NbN and Nb 3 Ge). A new energy balance is shown to give reasonable quantitative agreement of the dependence of the propagation velocity on the length of short normal domains. The steady state (zero velocity) measurements indicate the existence of two distinct situations for films on high thermal conductivity (sapphire) substrates. For low power per unit area the film and substrate have the same temperature, and the thermal properties of the substrate dominate. However, for higher power densities in short hot spots, the coupling is relatively weak and the thermal properties of the film alone are important. Here a connection is made between the critical current stability of superconducting films and a critical hot spot size for thermal propagation. As a result efficient heat removal is shown to dominate the stabilisation of superconducting films. The strong and weak coupling situations also lead to modifications of the models for propagation velocities on sapphire substrates. Self-healing of hot spots and other phenomena in superconducting film are explained. The potential use of the thermal propagation model in applications of superconductors, especially switches is discussed. (author)

Wave equations for pulse propagation

International Nuclear Information System (INIS)

Shore, B.W.

1987-01-01

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. 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

Voluntary resistance running with short distance enhances spatial memory related to hippocampal BDNF signaling.

Science.gov (United States)

Lee, Min Chul; Okamoto, Masahiro; Liu, Yu Fan; Inoue, Koshiro; Matsui, Takashi; Nogami, Haruo; Soya, Hideaki

2012-10-15

Although voluntary running has beneficial effects on hippocampal cognitive functions if done abundantly, it is still uncertain whether resistance running would be the same. For this purpose, voluntary resistance wheel running (RWR) with a load is a suitable model, since it allows increased work levels and resultant muscular adaptation in fast-twitch muscle. Here, we examined whether RWR would have potential effects on hippocampal cognitive functions with enhanced hippocampal brain-derived neurotrophic factor (BDNF), as does wheel running without a load (WR). Ten-week-old male Wistar rats were assigned randomly to sedentary (Sed), WR, and RWR (to a maximum load of 30% of body weight) groups for 4 wk. We found that in RWR, work levels increased with load, but running distance decreased by about half, which elicited muscular adaptation for fast-twitch plantaris muscle without causing any negative stress effects. Both RWR and WR led to improved spatial learning and memory as well as gene expressions of hippocampal BDNF signaling-related molecules. RWR increased hippocampal BDNF, tyrosine-related kinase B (TrkB), and cAMP response element-binding (CREB) protein levels, whereas WR increased only BDNF. With both exercise groups, there were correlations between spatial memory and BDNF protein (r = 0.41), p-CREB protein (r = 0.44), and work levels (r = 0.77). These results suggest that RWR plays a beneficial role in hippocampus-related cognitive functions associated with hippocampal BDNF signaling, even with short distances, and that work levels rather than running distance are more determinant of exercise-induced beneficial effects in wheel running with and without a load.

Cost-effective up to 40 Gbit/s transmission performance of 1310 nm directly modulated lasers for short to medium range distances

NARCIS (Netherlands)

Huiszoon, B.; Jonker, R.J.W.; Bennekom, van P.K.; Khoe, G.D.; Waardt, de H.

2005-01-01

This paper presents successful 20 and 40 Gb/s potentially low-cost transmission experiments using 1310 nm directly modulated distributed feedback lasers (DMLs) in the very-short- to medium-range distances. This paper will recommend operating conditions for error-free transmission at these bit rates

Short bi-iliac distance in prenatal Ullrich-Turner syndrome

DEFF Research Database (Denmark)

Hartling, Ulla B; Hansen, Birgit Fischer; Keeling, Jean W

2002-01-01

The purpose of the present study is to evaluate the bi-iliac distance and the caudo-cranial position of the iliac bones in Ullrich-Turner syndrome (UTS) fetuses compared to recently published standards for normal fetuses. Whole-body radiographs in antero-posterior projections of 24 UTS fetuses...... in normal fetuses. The bi-iliac distance and the iliac bone position have not previously been described in Ullrich-Turner syndrome fetuses....

On the cosmological gravitational waves and cosmological distances

Science.gov (United States)

Belinski, V. A.; Vereshchagin, G. V.

2018-03-01

We show that solitonic cosmological gravitational waves propagated through the Friedmann universe and generated by the inhomogeneities of the gravitational field near the Big Bang can be responsible for increase of cosmological distances.

Intraband effects on ultrafast pulse propagation in semiconductor ...

Indian Academy of Sciences (India)

High bit-rate (>10 Gb/s) signals are composed of very short pulses and propagation of such pulses through a semiconductor optical amplifier (SOA) requires consideration of intraband phenomena. Due to the intraband effects, the propagating pulse sees a fast recovering nonlinear gain which introduces less distortion in the ...

Fluid simulation for two laser beams co-propagating in underdense plasma

International Nuclear Information System (INIS)

Mahdy, A.I.

2004-09-01

2D simulations code was constructed in order simulate the interactions of two co-propagating laser beams with underdense plasma. Simulations results at different laser intensities and separation-distances between the beams centroids were presented. In the results the effects of the laser intensities on the self-focusing and merging of the propagating beams were shown. In addition, the influence of increasing the separation-distance on the beams stability and trajectories were studied. A comparison with previous simulations at similar conditions was carried out in order to evaluate the numerical technique used to solve the basic equations. (author)

Short philtrum

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/003302.htm Short philtrum To use the sharing features on this page, please enable JavaScript. A short philtrum is a shorter than normal distance between ...

Simulation of excitation and propagation of pico-second ultrasound

International Nuclear Information System (INIS)

Yang, Seung Yong; Kim, No Hyu

2016-01-01

This paper presents an analytic and numerical simulation of the generation and propagation of pico-second ultrasound with nano-scale wavelength, enabling the production of bulk waves in thin films. An analytic model of laser-matter interaction and elasto-dynamic wave propagation is introduced to calculate the elastic strain pulse in microstructures. The model includes the laser-pulse absorption on the material surface, heat transfer from a photon to the elastic energy of a phonon, and acoustic wave propagation to formulate the governing equations of ultra-short ultrasound. The excitation and propagation of acoustic pulses produced by ultra-short laser pulses are numerically simulated for an aluminum substrate using the finite-difference method and compared with the analytical solution. Furthermore, Fourier analysis was performed to investigate the frequency spectrum of the simulated elastic wave pulse. It is concluded that a pico-second bulk wave with a very high frequency of up to hundreds of gigahertz is successfully generated in metals using a 100-fs laser pulse and that it can be propagated in the direction of thickness for thickness less than 100 nm

Simulation of excitation and propagation of pico-second ultrasound

Energy Technology Data Exchange (ETDEWEB)

Yang, Seung Yong; Kim, No Hyu [Dept. of Mechanical Engineering, Korea University of Technology and Education, Chunan (Korea, Republic of)

2016-12-15

This paper presents an analytic and numerical simulation of the generation and propagation of pico-second ultrasound with nano-scale wavelength, enabling the production of bulk waves in thin films. An analytic model of laser-matter interaction and elasto-dynamic wave propagation is introduced to calculate the elastic strain pulse in microstructures. The model includes the laser-pulse absorption on the material surface, heat transfer from a photon to the elastic energy of a phonon, and acoustic wave propagation to formulate the governing equations of ultra-short ultrasound. The excitation and propagation of acoustic pulses produced by ultra-short laser pulses are numerically simulated for an aluminum substrate using the finite-difference method and compared with the analytical solution. Furthermore, Fourier analysis was performed to investigate the frequency spectrum of the simulated elastic wave pulse. It is concluded that a pico-second bulk wave with a very high frequency of up to hundreds of gigahertz is successfully generated in metals using a 100-fs laser pulse and that it can be propagated in the direction of thickness for thickness less than 100 nm.

Simulation of excitation and propagation of pico-second ultrasound

Energy Technology Data Exchange (ETDEWEB)

Yang, Seung Yong; Kim, No Kyu [Dept. of Mechanical Engineering, Korea University of Technology and Education, Chunan (Korea, Republic of)

2014-12-15

This paper presents an analytic and numerical simulation of the generation and propagation of pico-second ultrasound with nano-scale wavelength, enabling the production of bulk waves in thin films. An analytic model of laser-matter interaction and elasto-dynamic wave propagation is introduced to calculate the elastic strain pulse in microstructures. The model includes the laser-pulse absorption on the material surface, heat transfer from a photon to the elastic energy of a phonon, and acoustic wave propagation to formulate the governing equations of ultra-short ultrasound. The excitation and propagation of acoustic pulses produced by ultra-short laser pulses are numerically simulated for an aluminum substrate using the finite-difference method and compared with the analytical solution. Furthermore, Fourier analysis was performed to investigate the frequency spectrum of the simulated elastic wave pulse. It is concluded that a pico-second bulk wave with a very high frequency of up to hundreds of gigahertz is successfully generated in metals using a 100-fs laser pulse and that it can be propagated in the direction of thickness for thickness less than 100 nm.

Synaptic Contacts Enhance Cell-to-Cell Tau Pathology Propagation

Directory of Open Access Journals (Sweden)

Sara Calafate

2015-05-01

Full Text Available Accumulation of insoluble Tau protein aggregates and stereotypical propagation of Tau pathology through the brain are common hallmarks of tauopathies, including Alzheimer’s disease (AD. Propagation of Tau pathology appears to occur along connected neurons, but whether synaptic contacts between neurons are facilitating propagation has not been demonstrated. Using quantitative in vitro models, we demonstrate that, in parallel to non-synaptic mechanisms, synapses, but not merely the close distance between the cells, enhance the propagation of Tau pathology between acceptor hippocampal neurons and Tau donor cells. Similarly, in an artificial neuronal network using microfluidic devices, synapses and synaptic activity are promoting neuronal Tau pathology propagation in parallel to the non-synaptic mechanisms. Our work indicates that the physical presence of synaptic contacts between neurons facilitate Tau pathology propagation. These findings can have implications for synaptic repair therapies, which may turn out to have adverse effects by promoting propagation of Tau pathology.

Synaptic Contacts Enhance Cell-to-Cell Tau Pathology Propagation.

Science.gov (United States)

Calafate, Sara; Buist, Arjan; Miskiewicz, Katarzyna; Vijayan, Vinoy; Daneels, Guy; de Strooper, Bart; de Wit, Joris; Verstreken, Patrik; Moechars, Diederik

2015-05-26

Accumulation of insoluble Tau protein aggregates and stereotypical propagation of Tau pathology through the brain are common hallmarks of tauopathies, including Alzheimer's disease (AD). Propagation of Tau pathology appears to occur along connected neurons, but whether synaptic contacts between neurons are facilitating propagation has not been demonstrated. Using quantitative in vitro models, we demonstrate that, in parallel to non-synaptic mechanisms, synapses, but not merely the close distance between the cells, enhance the propagation of Tau pathology between acceptor hippocampal neurons and Tau donor cells. Similarly, in an artificial neuronal network using microfluidic devices, synapses and synaptic activity are promoting neuronal Tau pathology propagation in parallel to the non-synaptic mechanisms. Our work indicates that the physical presence of synaptic contacts between neurons facilitate Tau pathology propagation. These findings can have implications for synaptic repair therapies, which may turn out to have adverse effects by promoting propagation of Tau pathology. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Hadronic light-by-light scattering in the muon g-2: A new short-distance constraint on pion exchange

International Nuclear Information System (INIS)

Nyffeler, Andreas

2009-01-01

Recently it was pointed out that for the evaluation of the numerically dominant pion-exchange contribution to the hadronic light-by-light scattering correction in the muon g-2, a fully off-shell pion-photon-photon form factor should be used. Following this proposal, we first derive a new short-distance constraint on the off-shell form factor which enters at the external vertex for the muon g-2 and show that it is related to the quark condensate magnetic susceptibility in QCD. We then evaluate the pion-exchange contribution in the framework of large-N C QCD using an off-shell form factor which fulfills all short-distance constraints. With a value for the magnetic susceptibility as estimated in the same large-N C framework, we obtain the result a μ LbyL;π 0 =(72±12)x10 -11 . Updating our earlier results for the contributions from the exchanges of the η and η ' using simple vector-meson dominance form factors, we obtain a μ LbyL;PS =(99±16)x10 -11 for the sum of all light pseudoscalars. Combined with available evaluations for the other contributions to hadronic light-by-light scattering this leads to the new estimate a μ LbyL;had =(116±40)x10 -11 .

On the short-distance double penguin contribution to the K0-anti K0 mixing

International Nuclear Information System (INIS)

Eeg, J.O.

1985-01-01

We investigate the short-distance contribution of the double penguin box diagram to the K 0 -anti K 0 mixing. Compared with previous work of other authors, the present paper takes into account (i) the momentum dependence of the box loop, (ii) both the non-local part of the penguin and the previously considered local part and (iii) the crossed diagrams, which make a class of double penguin diagrams complete. With such new ingredients, we arrive at the conclusion that the SD part of the double penguin is physically irrelevant. After eliminating this particular mechanism for the K 0 -anti K 0 mixing, we point out other potentially relevant mechanisms. (orig.)

Time-domain analysis of second-harmonic generation of primary Lamb wave propagation in an elastic plate

International Nuclear Information System (INIS)

Deng Ming-Xi; Xiang Yan-Xun

2010-01-01

Within the second-order perturbation approximation, this paper investigates the physical process of generation of the time-domain second harmonic by a primary Lamb wave waveform in an elastic plate. The present work is performed based on the preconditions that the phase velocity matching is satisfied and that the transfer of energy from the primary Lamb wave to the double frequency Lamb wave is not zero. It investigates the influences of the difference between the group velocities of the primary Lamb wave and the double frequency Lamb wave, the propagation distance and the duration of the primary Lamb wave waveform on the envelope shape of the time-domain second harmonic. It finds that the maximum magnitude of the envelope of the second-harmonic waveform can grow within some propagation distance even if the condition of group velocity matching is not satisfied. Our analyses also indicate that the maximum magnitude of the envelope of the second-harmonic waveform is kept constant beyond a specific propagation distance. Furthermore, it concludes that the integration amplitude of the time-domain second-harmonic waveform always grows with propagation distance within the second-order perturbation. The present research yields new physical insight not previously available into the effect of generation of the time-domain second harmonic by propagation of a primary Lamb wave waveform

Change of Measure between Light Travel Time and Euclidean Distances

Directory of Open Access Journals (Sweden)

Heymann Y.

2013-04-01

Full Text Available The problem of cosmological distances is approached using a method based on the propagation of light in an expanding Universe. From the chan ge of measure between Light Travel Time and Euclidean Distances, a formula is deri ved to compute distances as a function of redshift. This formula is identical to Matti g’s formula (with q 0 = 1 / 2 which is based on Friedmann’s equations of general relativi ty.

Effects of laser beam propagation in a multilevel photoionization system

International Nuclear Information System (INIS)

Izawa, Y.; Nomaru, K.; Chen, Y. W.

1995-01-01

When the intense laser pulse propagates in the atomic vapor over a long distance, the laser pulse shape, the carrier frequency and the propagating velocity are greatly modified during the propagation by the resonant and/or the near-resonant interactions with atoms. We have been investigating these effects on the laser beam propagation experimentally and analytically. The simulation code named CEALIS-P has been developed, which employs the coupled three- level Bloch-Maxwell equations to study the atomic excitation and laser beam propagation simultaneously. Several features of the resonant and near-resonant effects based on the the self-induced transparency, the self-phase modulation and the nonlinear group velocity dispersion are described and the influences of such effects on the photoionization efficiency are analyzed.

Scintillation reduction for laser beams propagating through turbulent atmosphere

International Nuclear Information System (INIS)

Berman, G P; Gorshkov, V N; Torous, S V

2011-01-01

We numerically examine the spatial evolution of the structure of coherent and partially coherent laser beams, including the optical vortices, propagating in turbulent atmospheres. The influence of beam fragmentation and wandering relative to the axis of propagation (z-axis) on the value of the scintillation index (SI) of the signal at the detector is analysed. These studies were performed for different dimensions of the detector, distances of propagation, and strengths of the atmospheric turbulence. Methods for significantly reducing the SI are described. These methods utilize averaging of the signal at the detector over a set of partially coherent beams (PCBs). It is demonstrated that the most effective approach is using a set of PCBs with definite initial directions of propagation relative to the z-axis. This approach results in a significant compensation of the beam wandering which in many cases is the main contributor to the SI. A novel method is to generate the PCBs by combining two laser beams-Gaussian and vortex beams, with different frequencies (the difference between these two frequencies being significantly smaller than the frequencies themselves). In this case, the effective suppression of the SI does not require high-frequency modulators. This result is important for achieving gigabit data rates in long-distance laser communication through turbulent atmospheres.

Scintillation reduction for laser beams propagating through turbulent atmosphere

Energy Technology Data Exchange (ETDEWEB)

Berman, G P; Gorshkov, V N [Theoretical Division, T-4 and CNLS MS B213, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Torous, S V, E-mail: gpb@lanl.gov [National Technical University of Ukraine ' KPI' , 37 Peremogy Avenue, Building 7, Kiev-56, 03056 (Ukraine)

2011-03-14

We numerically examine the spatial evolution of the structure of coherent and partially coherent laser beams, including the optical vortices, propagating in turbulent atmospheres. The influence of beam fragmentation and wandering relative to the axis of propagation (z-axis) on the value of the scintillation index (SI) of the signal at the detector is analysed. These studies were performed for different dimensions of the detector, distances of propagation, and strengths of the atmospheric turbulence. Methods for significantly reducing the SI are described. These methods utilize averaging of the signal at the detector over a set of partially coherent beams (PCBs). It is demonstrated that the most effective approach is using a set of PCBs with definite initial directions of propagation relative to the z-axis. This approach results in a significant compensation of the beam wandering which in many cases is the main contributor to the SI. A novel method is to generate the PCBs by combining two laser beams-Gaussian and vortex beams, with different frequencies (the difference between these two frequencies being significantly smaller than the frequencies themselves). In this case, the effective suppression of the SI does not require high-frequency modulators. This result is important for achieving gigabit data rates in long-distance laser communication through turbulent atmospheres.

Characteristics of temporal modulation in nonlinear propagation of broad-band lasers stacked by chirped pulses

International Nuclear Information System (INIS)

Wang Youwen; Chen Liezun; Zhang Lifu; Deng Jianqin; Zhang Jin; Wen Shuangchun; Fu Xiquan; Fan Dianyuan

2010-01-01

Characteristics of the temporal modulation riding on broad-band lasers stacked by chirped pulses are numerically investigated in nonlinear propagation. For the case of normal dispersion, the temporal modulations induced by interference among pulses and added artificially to simulate the noise weaken gradually with the increase of the propagation distance. For the case of anomalous dispersion, the temporal modulations induced by interference among pulses grow slowly at first, and start to grow rapidly after a long propagation distance; in contrast, the temporal modulations added artificially grow rapidly from the begin, indicating that the temporal peak of damage risk to the optics can be formed easily. (authors)

Integral propagator solvers for Vlasov-Fokker-Planck equations

International Nuclear Information System (INIS)

Donoso, J M; Rio, E del

2007-01-01

We briefly discuss the use of short-time integral propagators on solving the so-called Vlasov-Fokker-Planck equation for the dynamics of a distribution function. For this equation, the diffusion tensor is singular and the usual Gaussian representation of the short-time propagator is no longer valid. However, we prove that the path-integral approach on solving the equation is, in fact, reliable by means of our generalized propagator, which is obtained through the construction of an auxiliary solvable Fokker-Planck equation. The new representation of the grid-free advancing scheme describes the inherent cross- and self-diffusion processes, in both velocity and configuration spaces, in a natural manner, although these processes are not explicitly depicted in the differential equation. We also show that some splitting methods, as well as some finite-difference schemes, could fail in describing the aforementioned diffusion processes, governed in the whole phase space only by the velocity diffusion tensor. The short-time transition probability offers a stable and robust numerical algorithm that preserves the distribution positiveness and its norm, ensuring the smoothness of the evolving solution at any time step. (fast track communication)

Long-distance calls in Neotropical primates

Directory of Open Access Journals (Sweden)

Oliveira Dilmar A.G.

2004-01-01

Full Text Available Long-distance calls are widespread among primates. Several studies concentrate on such calls in just one or in few species, while few studies have treated more general trends within the order. The common features that usually characterize these vocalizations are related to long-distance propagation of sounds. The proposed functions of primate long-distance calls can be divided into extragroup and intragroup ones. Extragroup functions relate to mate defense, mate attraction or resource defense, while intragroup functions involve group coordination or alarm. Among Neotropical primates, several species perform long-distance calls that seem more related to intragroup coordination, markedly in atelines. Callitrichids present long-distance calls that are employed both in intragroup coordination and intergroup contests or spacing. Examples of extragroup directed long-distance calls are the duets of titi monkeys and the roars and barks of howler monkeys. Considerable complexity and gradation exist in the long-distance call repertoires of some Neotropical primates, and female long-distance calls are probably more important in non-duetting species than usually thought. Future research must focus on larger trends in the evolution of primate long-distance calls, including the phylogeny of calling repertoires and the relationships between form and function in these signals.

From a distance: implications of spontaneous self-distancing for adaptive self-reflection.

Science.gov (United States)

Ayduk, Ozlem; Kross, Ethan

2010-05-01

Although recent experimental work indicates that self-distancing facilitates adaptive self-reflection, it remains unclear (a) whether spontaneous self-distancing leads to similar adaptive outcomes, (b) how spontaneous self-distancing relates to avoidance, and (c) how this strategy impacts interpersonal behavior. Three studies examined these issues demonstrating that the more participants spontaneously self-distanced while reflecting on negative memories, the less emotional (Studies 1-3) and cardiovascular (Study 2) reactivity they displayed in the short term. Spontaneous self-distancing was also associated with lower emotional reactivity and intrusive ideation over time (Study 1). The negative association between spontaneous self-distancing and emotional reactivity was mediated by how participants construed their experience (i.e., less recounting relative to reconstruing) rather than avoidance (Studies 1-2). In addition, spontaneous self-distancing was associated with more problem-solving behavior and less reciprocation of negativity during conflicts among couples in ongoing relationships (Study 3). Although spontaneous self-distancing was empirically related to trait rumination, it explained unique variance in predicting key outcomes. 2010 APA, all rights reserved

The effect of quintic nonlinearity on the propagation characteristics of dispersion managed optical solitons

International Nuclear Information System (INIS)

Konar, S.; Mishra, Manoj; Jana, S.

2006-01-01

The role of quintic nonlinearity on the propagation characteristics of optical solitons in dispersion managed optical communication systems has been presented in this paper. It has been shown that quintic nonlinearity has only marginal influence on single pulse propagation. However, numerical simulation has been undertaken to reveal that quintic nonlinearity reduces collision distance between neighbouring pulses of the same channel. It is found that for lower map strength the collapse distance between intra channel pulses is very much sensitive to the dispersion map strength

Characterizing information propagation through inter-vehicle communication on a simple network of two parallel roads

Science.gov (United States)

2010-10-01

In this report, we study information propagation via inter-vehicle communication along two parallel : roads. By identifying an inherent Bernoulli process, we are able to derive the mean and variance of : propagation distance. A road separation distan...

Extending Femtosecond Filamentation of High Power Laser Propagating in the Atmosphere

Science.gov (United States)

Eisenmann, Shmuel; Sivan, Yonatan; Fibich, Gadi; Zigler, Arie

2008-06-01

We show experimentally for ultrashort laser pulses propagating in air, that the filamentation distance of intense laser pulses in the atmosphere can be extended and controlled with a simple double-lens setup. Using this method we were able to achieve a 20-fold delay of the filamentation distance of non-chirped 120 fs pulses propagating in air, from 16 m to 330 m. At 330 m, the collapsing pulse is sufficiently powerful to create plasma filaments. We also show that the scatter of the filaments at 330 m can be significantly reduced by tilting the second lens. We derive a simple formula for the filamentation distance, and confirm its agreement with the experimental results. We also observe that delaying the onset of filamentation increases the filament length. To the best of our knowledge, this is the longest distance reported in the literature at which plasma filaments were created and controlled. Finally, we show that the peak power at the onset of collapse is significantly higher with the double-lens setup, compared with the standard negative chirping approach.

Short-range fundamental forces

International Nuclear Information System (INIS)

Antoniadis, I.; Baessler, S.; Buchner, M.; Fedorov, V.V.; Hoedl, S.; Nesvizhevsky, V.V.; Pignol, G.; Protasov, K.V.; Lambrecht, A.; Reynaud, S.; Sobolev, Y.

2010-01-01

We consider theoretical motivations to search for extra short-range fundamental forces as well as experiments constraining their parameters. The forces could be of two types: 1) spin-independent forces; 2) spin-dependent axion-like forces. Different experimental techniques are sensitive in respective ranges of characteristic distances. The techniques include measurements of gravity at short distances, searches for extra interactions on top of the Casimir force, precision atomic and neutron experiments. We focus on neutron constraints, thus the range of characteristic distances considered here corresponds to the range accessible for neutron experiments

Spectral changes in stochastic anisotropic electromagnetic beams propagating through turbulent ocean

Science.gov (United States)

Tang, Miaomiao; Zhao, Daomu

2014-02-01

Based on the extended Huygens-Fresnel principle and the unified theory of coherence and polarization of light, the spectral changes of stochastic anisotropic electromagnetic beams propagating through oceanic turbulence are revealed. As an example, some numerical calculations are illustrated for an anisotropic electromagnetic Gaussian Schell-model beam propagating in a homogeneous and isotropic turbulent ocean. It is shown that, under the influence of oceanic turbulence, the on-axis spectrum is always blue-shifted along with the propagation distance, however, for the off-axis positions, red-blue spectral switch can be found.

Photon and energy propagation in Cd Se quantum dot systems

International Nuclear Information System (INIS)

Alves, Guilherme A.; Santos, Erasto J.; Monte, Adamo F.G.

2011-01-01

Full text. Photon propagation is a crucial process in a wide type of optical materials being responsible for the dynamics and excitation spreading. The addition of Cd Se quantum dots (QDs) into a polystyrene (PS) matrix introduces new properties in the polymeric matrix making this new system a good candidate for improvement in light- emitting devices. A confocal microscope was adapted to scan the spatial distribution of emitted luminescence from the sample surface. Energy transfer processes could be associated with the photon propagation provided by the measured luminescence spatial distribution. We proposed that this energy propagation is caused by the photons capture and emission between the dots and besides other mechanics such as electronic transfer, hopping and resonance. This dynamic process can be understood by the spatial migration of excited states. These facts demonstrate the great importance of the energy transfer, absorption and capture processes in a QD system for the improvement of optical electronic devices. It has been found that re-absorption by ground and excited states plays an important role for the energy propagation. The investigation have been done for a wide range of inter-dot distance in such a way that we could observe how the energy transfer behaves according to this distance. We observed that the photon migration length (PML) increases by increasing the QD concentration and reaches the highest value for a given QD concentration, i.e., for a specific inter-dot distance. However, above this concentration the PML starts to decrease. This behavior indicates that the inter-dots distance is crucial in order to get the highest energy flux inside the sample. Thus, by measuring the PML and its wavelength dependence it is possible to understand the whole dynamics in the QD/PS system. All the processes verified so far give us the possibility to classify the QD/PS system as a good candidate to be employed in an optical QD-based device

Studies of nonlinear femtosecond pulse propagation in bulk materials

Science.gov (United States)

Eaton, Hilary Kaye

2000-10-01

Femtosecond pulse lasers are finding widespread application in a variety of fields including medical research, optical switching and communications, plasma formation, high harmonic generation, and wavepacket formation and control. As the number of applications for femtosecond pulses increases, so does the need to fully understand the linear and nonlinear processes involved in propagating these pulses through materials under various conditions. Recent advances in pulse measurement techniques, such as frequency-resolved optical gating (FROG), allow measurement of the full electric field of the pulse and have made detailed investigations of short- pulse propagation effects feasible. In this thesis, I present detailed experimental studies of my work involving nonlinear propagation of femtosecond pulses in bulk media. Studies of plane-wave propagation in fused silica extend the SHG form of FROG from a simple pulse diagnostic to a useful method of interrogating the nonlinear response of a material. Studies of nonlinear propagation are also performed in a regime where temporal pulse splitting occurs. Experimental results are compared with a three- dimensional nonlinear Schrödinger equation. This comparison fuels the development of a more complete model for pulse splitting. Experiments are also performed at peak input powers above those at which pulse splitting is observed. At these higher intensities, a broadband continuum is generated. This work presents a detailed study of continuum behavior and power loss as well as the first near-field spatial- spectral measurements of the generated continuum light. Nonlinear plane-wave propagation of short pulses in liquids is also investigated, and a non-instantaneous nonlinearity with a surprisingly short response time of 10 fs is observed in methanol. Experiments in water confirm that this effect in methanol is indeed real. Possible explanations for the observed effect are discussed and several are experimentally rejected. This

On the Propagation of Light in an Expanding Universe

Directory of Open Access Journals (Sweden)

Yuri Heymann

2013-07-01

Full Text Available The equation of the propagation of light in an expanding Universe is derived based on the definition of comoving distances. A numerical method is proposed to solve this equation jointly with the Friedmann equation. As the equation of the propagation of light in an expanding Universe defines a horizon of the visible Universe, this puts a constraint on cosmological models in order to be consistent with an upper limit for redshifts observed from galaxies. This puzzle is challenging current expansionist cosmological models.

Topics in quantum chromodynamics: two loop Feynman gauge calculation of the meson nonsinglet evolution potential and fourier acceleration of the calculation of the fermion propagator in lattice QCD

International Nuclear Information System (INIS)

Katz, G.R.

1986-01-01

Part I of this thesis is a perturbative QCD calculation to two loops of the meson nonsinglet evolution potential in the Feynman gauge. The evolution potential describes the momentum dependence of the distribution amplitude. This amplitude is needed for the calculation to beyond leading order of exclusive amplitudes and form factors. Techniques are presented that greatly simplify the calculation. The results agree with an independent light-cone gauge calculation and disagree with predictions made using conformal symmetry. In Part II the author presents a Fourier acceleration method that is effective in accelerating the computation of the fermion propagator in lattice QCD. The conventional computation suffers from critical slowing down: the long distance structure converges much slower than the short distance structure. by evaluating the fermion propagator in momentum space using fast Fourier transforms, it is possible to make different length scales converge at a more equal rate. From numerical experiments made on a 8 4 lattice, the author obtained savings of a factor of 3 to 4 by using Fourier acceleration. He also discusses the important of gauge fixing when using Fourier acceleration

Propagation in a waveguide with range-dependent seabed properties.

Science.gov (United States)

Holland, Charles W

2010-11-01

The ocean environment contains features affecting acoustic propagation that vary on a wide range of time and space scales. A significant body of work over recent decades has aimed at understanding the effects of water column spatial and temporal variability on acoustic propagation. Much less is understood about the impact of spatial variability of seabed properties on propagation, which is the focus of this study. Here, a simple, intuitive expression for propagation with range-dependent boundary properties and uniform water depth is derived. It is shown that incoherent range-dependent propagation depends upon the geometric mean of the seabed plane-wave reflection coefficient and the arithmetic mean of the cycle distance. Thus, only the spatial probability distributions (pdfs) of the sediment properties are required. Also, it is shown that the propagation over a range-dependent seabed tends to be controlled by the lossiest, not the hardest, sediments. Thus, range-dependence generally leads to higher propagation loss than would be expected, due for example to lossy sediment patches and/or nulls in the reflection coefficient. In a few instances, propagation over a range-dependent seabed can be calculated using range-independent sediment properties. The theory may be useful for other (non-oceanic) waveguides.

Double peak-induced distance error in short-time-Fourier-transform-Brillouin optical time domain reflectometers event detection and the recovery method.

Science.gov (United States)

Yu, Yifei; Luo, Linqing; Li, Bo; Guo, Linfeng; Yan, Jize; Soga, Kenichi

2015-10-01

The measured distance error caused by double peaks in the BOTDRs (Brillouin optical time domain reflectometers) system is a kind of Brillouin scattering spectrum (BSS) deformation, discussed and simulated for the first time in the paper, to the best of the authors' knowledge. Double peak, as a kind of Brillouin spectrum deformation, is important in the enhancement of spatial resolution, measurement accuracy, and crack detection. Due to the variances of the peak powers of the BSS along the fiber, the measured starting point of a step-shape frequency transition region is shifted and results in distance errors. Zero-padded short-time-Fourier-transform (STFT) can restore the transition-induced double peaks in the asymmetric and deformed BSS, thus offering more accurate and quicker measurements than the conventional Lorentz-fitting method. The recovering method based on the double-peak detection and corresponding BSS deformation can be applied to calculate the real starting point, which can improve the distance accuracy of the STFT-based BOTDR system.

High-order harmonics from an ultraintense laser pulse propagating inside a fiber

International Nuclear Information System (INIS)

Bulanov, S.V.; Esirkepov, T. Zh.; Naumova, N.M.; Sokolov, I.V.

2003-01-01

A strong effect of high harmonic radiation during the propagation of a high intensity short laser pulse in a thin wall hollow channel ('fiber') is found and studied via relativistic particle-in-cell simulations. The fiber has finite width walls comprised of an overdense plasma. Only the harmonic radiation with the harmonic number above critical value, for which the fiber walls are transparent, propagates outwards in the form of a coherent ultrashort pulse with very short wavelength

Electromagnetically induced guiding and superradiant amplification of counter-propagating lasers in plasma

International Nuclear Information System (INIS)

Shvets, G.; Fisch, N.J.; Pukhov, A.

1999-01-01

The interaction of counter-propagating laser pulses in a plasma is considered. When the frequencies of the two lasers are close, nonlinear modification of the refraction index results in the mutual focusing of the two beams. A short (of order the plasma period) laser pulse can be nonlinearly focused by a long counter-propagating beam which extends over the entire guiding length. It is also demonstrated that a short ( p ) laser pulse can be superradiantly amplified by a counter-propagating long low-intensity pump while remaining ultra-short. Particle-in-Cell simulations indicate that pump depletion can be as high as 40%. This implies that the long pump is efficiently compressed in time without frequency chirping and pulse stretching, making the superradiant amplification an interesting alternative to the conventional method of producing ultra-intense pulses by the chirped-pulse amplification. copyright 1999 American Institute of Physics

Unstable propagation of a Gaussian laser beam in a plasma waveguide

International Nuclear Information System (INIS)

Feit, M.D.; Maiden, D.E.

1976-01-01

Laser heating of long magnetically confined plasma columns to fusion temperatures requires propagation of a trapped laser beam over considerable distances. The present paper employs the parabolic approximation to the wave equation to analyze the propagation of a Gaussian beam through a plasma with a parabolic transverse density profile. Although propagation is stable in the axially uniform case, exhibiting alternate focusing and defocusing of the beam, it is unstable to small axial perturbations of certain wavelengths. In particular, an exponentially growing beam radius results from perturbations at wavelengths near that associated with the alternate focusing and defocusing mentioned above

M2 qualify laser beam propagation

International Nuclear Information System (INIS)

Abdelhalim, Bencheikh; Mohamed, Bouafia

2010-01-01

One of the most important properties of a laser resonator is the highly collimated or spatially coherent nature of the laser output beam. Laser beam diameter and quality factor M 2 are significant parameters in a wide range of laser applications. This is because the spatial beam quality determines how closely the beam can be focused or how well the beam propagates over long distances without significant dispersion. In the present paper we have used three different methods to qualify the spatial structure of a laser beam propagating in free space, the results are obtained and discussed, and we have found that the Wigner distribution function is a powerful tool which allows a global characterization of any kind of beam

Distance relay performance in future converter dominated power systems

DEFF Research Database (Denmark)

Sarkar, Moumita; Jia, Jundi; Yang, Guangya

2017-01-01

Increasing penetration of converter-based generations in power system has led to new system challenges. Short circuit power response from converter-based generations is different from that of traditional synchronous generators. Power electronic converters can be designed for over-current only up ...... of converter controls on fault current response of converter-based generations is also investigated. Index Terms—Converter control, distance relays, power system protection, system modelling....... to 1.1-1.25 times of its nominal value. Low availability of short circuit power can cause many challenges such as misoperation of distance relays. The aim of this paper is to investigate the effect of converter dominated systems on performance of distance relays. Backup functionality of the distance...... relay is major concern as miscoordination of backup relays in case of cascading faults can lead to severe stress in system, which can develop into blackout. In this paper, response of relays in traditional system is compared with response of relays in low short-circuit-current power systems. Impact...

Composite optical vortices in noncollinear Laguerre–Gaussian beams and their propagation in free space

International Nuclear Information System (INIS)

Chen Ke; Liu Pusheng; Lü Baida

2008-01-01

Taking two Laguerre—Gaussian beams with topological charge l = ± 1 as an example, this paper studies the composite optical vortices formed by two noncollinear Laguerre—Gaussian beams with different phases, amplitudes, waist widths, off-axis distances, and their propagation in free space. It is shown by detailed numerical illustrative examples that the number and location of composite vortices at the waist plane are variable by varying the relative phase β, amplitude ratio η, waist width ratio ζ, or off-axis distance ratio μ. The net topological charge l net is not always equal to the sum l sum of charges of the two component beams. The motion, creation and annihilation of composite vortices take place in the free-space propagation, and the net charge during the propagation remains unchanged and equals to the net charge at the waist plane

Short-distance behavior of the Bethe--Salpeter wave function in the ladder approximation

International Nuclear Information System (INIS)

Guth, A.H.; Soper, D.E.

1975-01-01

We investigate the short-distance behavior of the (Wick-rotated) Bethe--Salpeter wave function for the two spin-1/2 quarks bound by the exchange of a massive vector meson. We use the ladder-model kernel, which has the same p -4 scaling behavior as the true kernel in a theory with a fixed point of the renormalization group at g not equal to 0. For a bound state with the quantum numbers of the pion, the leading asymptotic behavior is chi (q/sup μ/) approx. cq/sup -4 + epsilon(g)/γ 5 , where epsilon (g) =1- (1-g 2 /π 2 ) 1 / 2 . Our method also provides the full asymptotic series, although it should be noted that the nonleading terms will depend on the nonleading behavior of the ladder-model kernel. A general term has the form cq - /sup a/(lnq)/sup n/phi (q/sup μ/), where c is an unknown constant, a may be integral or nonintegral, n is an integer, and phi (q/sup μ/) is a representation function of the rotation group in four dimensions

Paraxial propagation dynamics of the radially polarized Airy beams in uniaxial crystals orthogonal to the optical axis.

Science.gov (United States)

Xie, Jintao; Zhang, Jianbin; Zheng, Xitao; Ye, Junran; Deng, Dongmei

2018-04-30

We study the paraxial propagation of the radially polarized Airy beams (RPAiBs) in uniaxial crystals orthogonal to the optical axis analytically and numerically. The propagation trajectory, the intensity and the radiation forces of the RPAiBs are investigated and the properties are elucidated by numerical examples in this paper. Results show that the RPAiBs evolve into the beams produced by the x-direction electric field (RPAiXBs) and the y-direction electric field (PRAiYBs) which are totally different in uniaxial crystals. During the propagation, the intensity of the RPAiXBs transfers from the side lobe in the x-direction to the main lobe and finally returns to the side lobe in the x-direction again, but that of the RPAiYBs transfers from the side lobe in the y-direction to the main lobe and flows to the side lobe in the x-direction at last. The effect of the intensity focusing for the RPAiXBs can be modulated by the ratio of the extraordinary index (ne) to the ordinary index (no) in anisotropic medium, which contributes to the intensity focusing of the RPAiBs in a short distance a lot. We can adjust the intensity distribution especially the focusing position, the propagation trajectory and the radiation forces distributions of the RPAiXBs through choosing an appropriate value of the ratio of ne to no to meet the actual usage accordingly.

Short distance movement of genomic negative strands in a host and nonhost for Sugarcane mosaic virus (SCMV

Directory of Open Access Journals (Sweden)

Hernández-Vela Juan

2011-01-01

Full Text Available Abstract Background In order to obtain an initial and preliminary understanding of host and nonhost resistance in the initial step of potyvirus replication, both positive and negative Sugarcane mosaic virus (SCMV strands where traced in inoculated and systemic leaves in host and nonhost resistant maize and sugarcane for one Mexican potyviral isolate (SCMV-VER1. Intermediary replication forms, such as the negative viral strand, seem to only move a short distance as surveyed by RT-PCR analysis and ELISA in different leaves. Virus purification was also done in leaves and stems. Results Susceptible maize plants allowed for viral SCMV replication, cell-to-cell, and long distance movement, as indicated by the presence of the coat protein along the plant. In the host resistant maize plants for the SCMV-VER1 isolate, the virus was able to establish the disease though the initial steps of virus replication, as detected by the presence of negative strands, in the basal area of the inoculated leaves at six and twelve days post inoculation. The nonhost sugarcane for SCMV-VER1 and the host sugarcane for SCMV-CAM6 also allowed the initial steps of viral replication for the VER1 isolate in the local inoculated leaf. SCMV-VER1 virions could be extracted from stems of susceptible maize with higher titers than leaves. Conclusion Nonhost and host resistance allow the initial steps of potyvirus SCMV replication, as shown by the negative strands' presence. Furthermore, both hosts allow the negative viral strands' local movement, but not their systemic spread through the stem. The presence of larger amounts of extractable virions from the stem (as compared to the leaves in susceptible maize lines suggests their long distance movement as assembled particles. This will be the first report suggesting the long distance movement of a monocot potyvirus as a virion.

Luminosity distance for Born-Infeld electromagnetic waves propagating in a cosmological magnetic background

Energy Technology Data Exchange (ETDEWEB)

Aiello, Matias; Bengochea, Gabriel R; Ferraro, Rafael, E-mail: aiello@iafe.uba.ar, E-mail: gabriel@iafe.uba.ar, E-mail: ferraro@iafe.uba.ar [Instituto de Astronomia y Fisica del Espacio, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina); Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina)

2008-06-15

Born-Infeld electromagnetic waves interacting with a static magnetic background in an expanding universe are studied. The non-linear character of Born-Infeld electrodynamics modifies the relation between the energy flux and the distance to the source, which gains a new dependence on the redshift that is governed by the background field. We compute the luminosity distance as a function of the redshift and compare with Maxwellian curves for supernovae type Ia.

COTS low-cost 622-Mb/s free-space laser communications link for short-distance commercial applications

Science.gov (United States)

Morrison, Kenneth A.

2000-05-01

The results from a low cost 622 Mb/s, free-space laser communication link operating at 850 nm for short distance commercial applications is presented. The test results demonstrate the use of a free-space laser communications transceiver for building to building applications such as LAN, WAN and ATM operations, etc. This illustrates the potential for wide-use commercial computer network applications. The transceiver is constructed of commercial off-the-shelf materials for the development of a low-cost laser communications data link. The test system configuration utilizes standard Personal Computers with network cards and signal conversion cards for the copper to optical medical conversion. These tests precede the development of an increased data rate device operating at 2.5 Gb/s.

SUNWARD-PROPAGATING ALFVÉNIC FLUCTUATIONS OBSERVED IN THE HELIOSPHERE

Energy Technology Data Exchange (ETDEWEB)

Li, Hui; Wang, Chi [State Key Laboratory of Space Weather, National Space Science Center, CAS, Beijing, 100190 (China); Belcher, John W.; Richardson, John D. [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA (United States); He, Jiansen, E-mail: hli@spaceweather.ac.cn [School of Earth and Space Sciences, Peking University, Beijing, 100871 (China)

2016-06-10

The mixture/interaction of anti-sunward-propagating Alfvénic fluctuations (AFs) and sunward-propagating Alfvénic fluctuations (SAFs) is believed to result in the decrease of the Alfvénicity of solar wind fluctuations with increasing heliocentric distance. However, SAFs are rarely observed at 1 au and solar wind AFs are found to be generally outward. Using the measurements from Voyager 2 and Wind , we perform a statistical survey of SAFs in the heliosphere inside 6 au. We first report two SAF events observed by Voyager 2 . One is in the anti-sunward magnetic sector with a strong positive correlation between the fluctuations of magnetic field and solar wind velocity. The other one is in the sunward magnetic sector with a strong negative magnetic field—velocity correlation. Statistically, the percentage of SAFs increases gradually with heliocentric distance, from about 2.7% at 1.0 au to about 8.7% at 5.5 au. These results provide new clues for understanding the generation mechanism of SAFs.

'Bluetooth' for radio-connecting short distance; Kinkyori wo musen setsuzokusuru 'Bluetooth'

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

'Bluetooth' is a new connection method for radio-connecting a short distance by means of mobile equipment including a note PC, PC peripheral equipment and portable telephone, using 2.4GHz ISM (Industrial Scientific Medical) band. It is capable of making a network without a complex operation, enabling data and audio communications. In May, 1998, an operation for deciding on the specifications was started under the leadership of five companies consisting of Ericsson, Nokia, Intel, IBM and Toshiba, with the specification version 1.0 completed in July, 1999 and opened to the public. (readable on http://www.bluetooth.com). Using such features as low power consumption, low cost and small size, the 'Bluetooth' will be mounted on various kinds of mobile equipment and developed in mobile PAN (Personal Area Network). (translated by NEDO)

A model for high-cycle fatigue crack propagation

Energy Technology Data Exchange (ETDEWEB)

Balbi, Marcela Angela [Rosario National Univ. (Argentina); National Council of Scientific Research and Technology (CONICET) (Argentina)

2017-02-01

This paper deals with the prediction of high-cycle fatigue behavior for four different materials (7075-T6 alloy, Ti-6Al-4 V alloy, JIS S10C steel and 0.4 wt.-% C steel) using Chapetti's approach to estimate the fatigue crack propagation curve. In the first part of the paper, a single integral equation for studying the entire propagation process is determined using the recent results of Santus and Taylor, which consider a double regime of propagation (short and long cracks) characterized by the model of El Haddad. The second part of the paper includes a comparison of the crack propagation behavior model proposed by Navarro and de los Rios with the one mentioned in the first half of this work. The results allow us to conclude that the approach presented in this paper is a good and valid estimation of high-cycle fatigue crack propagation using a single equation to describe the entire fatigue crack regime.

Quantum chromodynamics at large distances

International Nuclear Information System (INIS)

Arbuzov, B.A.

1987-01-01

Properties of QCD at large distances are considered in the framework of traditional quantum field theory. An investigation of asymptotic behaviour of lower Green functions in QCD is the starting point of the approach. The recent works are reviewed which confirm the singular infrared behaviour of gluon propagator M 2 /(k 2 ) 2 at least under some gauge conditions. A special covariant gauge comes out to be the most suitable for description of infrared region due to absence of ghost contributions to infrared asymptotics of Green functions. Solutions of Schwinger-Dyson equation for quark propagator are obtained in this special gauge and are shown to possess desirable properties: spontaneous breaking of chiral invariance and nonperturbative character. The infrared asymptotics of lower Green functions are used for calculation of vacuum expectation values of gluon and quark fields. These vacuum expectation values are obtained in a good agreement with the corresponding phenomenological values which are needed in the method of sum rules in QCD, that confirms adequacy of the infrared region description. The consideration of a behaviour of QCD at large distances leads to the conclusion that at contemporary stage of theory development one may consider two possibilities. The first one is the well-known confinement hypothesis and the second one is called incomplete confinement and stipulates for open color to be observable. Possible manifestations of incomplete confinement are discussed

Beam wandering statistics of twin thin laser beam propagation under generalized atmospheric conditions.

Science.gov (United States)

Pérez, Darío G; Funes, Gustavo

2012-12-03

Under the Geometrics Optics approximation is possible to estimate the covariance between the displacements of two thin beams after they have propagated through a turbulent medium. Previous works have concentrated in long propagation distances to provide models for the wandering statistics. These models are useful when the separation between beams is smaller than the propagation path-regardless of the characteristics scales of the turbulence. In this work we give a complete model for these covariances, behavior introducing absolute limits to the validity of former approximations. Moreover, these generalizations are established for non-Kolmogorov atmospheric models.

Correlation between discrete probability and reaction front propagation rate in heterogeneous mixtures

Science.gov (United States)

Naine, Tarun Bharath; Gundawar, Manoj Kumar

2017-09-01

We demonstrate a very powerful correlation between the discrete probability of distances of neighboring cells and thermal wave propagation rate, for a system of cells spread on a one-dimensional chain. A gamma distribution is employed to model the distances of neighboring cells. In the absence of an analytical solution and the differences in ignition times of adjacent reaction cells following non-Markovian statistics, invariably the solution for thermal wave propagation rate for a one-dimensional system with randomly distributed cells is obtained by numerical simulations. However, such simulations which are based on Monte-Carlo methods require several iterations of calculations for different realizations of distribution of adjacent cells. For several one-dimensional systems, differing in the value of shaping parameter of the gamma distribution, we show that the average reaction front propagation rates obtained by a discrete probability between two limits, shows excellent agreement with those obtained numerically. With the upper limit at 1.3, the lower limit depends on the non-dimensional ignition temperature. Additionally, this approach also facilitates the prediction of burning limits of heterogeneous thermal mixtures. The proposed method completely eliminates the need for laborious, time intensive numerical calculations where the thermal wave propagation rates can now be calculated based only on macroscopic entity of discrete probability.

Faraday tarotion: new parameter for electromagnetic pulse propagation in magnetoplasma

International Nuclear Information System (INIS)

Bloch, S.C.; Lyons, P.W.

1976-01-01

Extreme distortion and time-dependent Faraday rotation occur for propagation of short electromagnetic pulses in magnetoplasma, for some ranges of plasma parameters. In order to relate pulse and monochromatic waves for propagation-path diagnostic purposes, a new parameter is introduced for the transmitted pulse train which has properties that correspond very accurately to results that would be expected for Faraday rotation of a continuous wave having the central frequency of the incident pulse spectrum. Results for 5-ns pulses (10 GHz) are presented for varying propagating length, static magnetic field, electron density, and collisional absorption

Parametric Excitations of Fast Plasma Waves by Counter-propagating Laser Beams

International Nuclear Information System (INIS)

Shvets, G.; Fisch, N.J.

2001-01-01

Short- and long-wavelength plasma waves can become strongly coupled in the presence of two counter-propagating laser pump pulses detuned by twice the cold plasma frequency. What makes this four-wave interaction important is that the growth rate of the plasma waves occurs much faster than in the more obvious co-propagating geometry

Computer modeling of inelastic wave propagation in porous rock

International Nuclear Information System (INIS)

Cheney, J.A.; Schatz, J.F.; Snell, C.

1979-01-01

Computer modeling of wave propagation in porous rock has several important applications. Among them are prediction of fragmentation and permeability changes to be caused by chemical explosions used for in situ resource recovery, and the understanding of nuclear explosion effects such as seismic wave generation, containment, and site hardness. Of interest in all these applications are the distance from the source to which inelastic effects persist and the amount of porosity change within the inelastic region. In order to study phenomena related to these applications, the Cam Clay family of models developed at Cambridge University was used to develop a similar model that is applicable to wave propagation in porous rock. That model was incorporated into a finite-difference wave propagation computer code SOC. 10 figures, 1 table

Galaxy as fundamental calibrator of the extragalactic distance scale. I. The basic scale factors of the galaxy and two kinematic tests of the long and short distance scales

International Nuclear Information System (INIS)

de Vaucouleurs, G.

1983-01-01

A new version of the oldest approach to estimating the distances of galaxies (direct comparison with our Galaxy) is proposed to relate the extragalactic distance scale to the basic metric, photometric, and kinematic scale factors of the Galaxy. These include the galactocentric distance of the Sun, R/sub sun/, the total magnitude of the Galaxy, M 0 /sub T/, and its spheroidal component, M 0 /sub I/, the galactic rotation velocity of the local standard of rest, V(R/sub sun/), the central velocity dispersion sigma/sub ν/(0) of the spheroidal component, and related parameters. The following ''most probable'' values and their mean errors are adopted from a variety of recent determinations: morphological type of galaxy, SABX(rXs)bc(T = 4 +- 0.5), R/sub sun/ = 8.5 +- 0.5 kpc, M 0 /sub T/(B) = -20.2 +- 0.15, (B-V) 0 /sub T/ = 0.53 +- 0.04, M 0 /sub I/(B) = -18.2 +- 0.3, (B-V) 0 /sub I/ = 0.65 +- 0.05, V(R/sub sun/) = 220 +- 15 km s -1 , sigma/sub ν/(0) = 130 +- 7 km s -1 . 1. The zero points of the Tully-Fisher (T-F) relations, -M 0 /sub T/(B) = a(B)+5(log V/sub M/ -2.2), in the B/sub T/ system, and -M/sup c/(H) = a(H)+10(log W 20 -2.5), in the H/sub -0.5/ system, are determined in terms of the galactocentric distance of the Sun R/sub sun/, and the galactic rotation velocity of the local standard of rest, V(R/sub sun/)equivalentV 0 roughly-equalV/sub M/, or the corresponding line width W 20 . The galactic zero point a(B) agrees within 0.1 mag with that (19.4 +- 0.15) previously derived on the short scale from 11 nearby calibrating galaxies

Super-Alfvénic Propagation and Damping of Reconnection Onset Signatures

Science.gov (United States)

Sharma Pyakurel, P.; Shay, M. A.; Haggerty, C. C.; Parashar, T. N.; Drake, J. F.; Cassak, P. A.; Gary, S. Peter

2018-01-01

The quadrupolar out-of-plane Hall magnetic field generated during collisionless reconnection propagates away from the x line as a kinetic Alfvén wave (KAW). While it has been shown that this KAW carries substantial Poynting flux and propagates super-Alfvenically, how this KAW damps as it propagates away from the x line is not well understood. In this study, this damping is examined using kinetic particle-in-cell simulations of antiparallel symmetric magnetic reconnection in a one-dimensional current sheet equilibrium. In the reconnection simulations, the KAW wave vector has a typical magnitude comparable to an inverse fluid Larmor radius (effectively an inverse ion Larmor radius) and a direction of 85-89° relative to the local magnetic field. We find that the damping of the reconnection KAW is consistent with linear Landau damping results from a numerical Vlasov dispersion solver. This knowledge allows us to generalize our damping predictions to regions in the magnetotail and solar corona where the magnetic geometry can be approximated as a current sheet. For the magnetotail, the KAW from reconnection will not damp away before propagating the approximately 20 Earth radii associated with global magnetotail distances. For the solar corona, on the other hand, these KAWs will completely damp before reaching the distances comparable to the flare loop length.

Path Loss Analysis of WSN Wave Propagation in Vegetation

International Nuclear Information System (INIS)

Sabri, Naseer; Aljunid, S A; Ahmad, R B; Malek, M F; Salim, M S; Kamaruddin, R

2013-01-01

Deployment of a successful wireless sensor network requires precise prediction models that provide a reliable communication links of wireless nodes. Prediction models fused with foliage models provide sensible parameters of wireless nodes separation distance, antenna height, and power transmission which affect the reliability and communication coverage of a network. This paper review the line of sight and the two ray propagation models combined with the most known foliage models that cover the propagation of wireless communications in vegetative environments, using IEEE 802.15.4 standard. Simulation of models is presented and the impacts of the communication parameters, environment and vegetation have been reported.

Experimental study on propagation properties of large size TEM antennas

International Nuclear Information System (INIS)

Zhang Guowei; Wang Haiyang; Chen Weiqing; Wang Wei; Zhu Xiangqin; Xie Linshen

2014-01-01

The propagation properties of large size TEM antennas were studied by experiment. The size of the TEM antennas is 60 m × 20 m × 10 m and the character Impedance is 120 Ω. A kind of dielectric foil switch is designed compactly with TEM antennas which can generate double exponential waveform with altitude of 10 kV and rise time of l.2 ns. The radiated field distribution was measured. The relationship between rise time/altitude and distance were provided, and the propagation properties of large size TEM antennas were summarized. (authors)

Preventing Unofficial Information Propagation

Science.gov (United States)

Le, Zhengyi; Ouyang, Yi; Xu, Yurong; Ford, James; Makedon, Fillia

Digital copies are susceptible to theft and vulnerable to leakage, copying, or manipulation. When someone (or some group), who has stolen, leaked, copied, or manipulated digital documents propagates the documents over the Internet and/or distributes those through physical distribution channels many challenges arise which document holders must overcome in order to mitigate the impact to their privacy or business. This paper focuses on the propagation problem of digital credentials, which may contain sensitive information about a credential holder. Existing work such as access control policies and the Platform for Privacy Preferences (P3P) assumes that qualified or certified credential viewers are honest and reliable. The proposed approach in this paper uses short-lived credentials based on reverse forward secure signatures to remove this assumption and mitigate the damage caused by a dishonest or honest but compromised viewer.

Polycomb domain formation depends on short and long distance regulatory cues.

Directory of Open Access Journals (Sweden)

Bernd Schuettengruber

Full Text Available BACKGROUND: Polycomb group (PcG proteins dynamically define cellular identities through the epigenetic repression of key developmental genes. In Drosophila, cis-regulatory regions termed PcG response elements (PREs act as nucleation sites for PcG proteins to create large repressive PcG domains that are marked by trimethylation of lysine 27 on histone H3 (H3K27me3. In addition to an action in cis, PREs can interact over long distances, thereby enhancing PcG dependent silencing. How PcG domains are established, which factors limit their propagation in cis, and how long range interactions of PREs in trans affect the chromatin structure is largely unknown. PRINCIPAL FINDINGS: We demonstrate that the insertion of a PRE-containing transgene in the Drosophila genome generates an artificial PcG domain and we analyze its organization by quantitative ChIP and ChIP-on-chip experiments. Intriguingly, a boundary element and known insulator proteins do not necessarily interfere with spreading of H3K27me3. Instead, domain borders correlate with the presence of promoter regions bound by RNA Polymerase II and active chromatin marks. In contrast, genes that are silent during early fly development get included within the PcG domain and this incorporation interferes with gene activation at later developmental stages. Moreover, trans-interaction of the transgenic PRE with its homologous endogenous PRE results in increased PcG binding, correlating with reinforced silencing of genes within the domain borders. CONCLUSIONS: Our results suggest that higher-order organization of PcG-bound chromatin can stabilize gene silencing within PcG domains. Further we propose that multi-protein complexes associated with active promoters are able to define the limits of PcG domains. Future work aimed to pinpoint the factors providing this barrier function will be required to understand the precise molecular mechanism by which active promoter regions can act as boundaries to stop

The dual description of long-distance QCD (Dual QCD)

International Nuclear Information System (INIS)

Baker, M.

1990-01-01

We construct and solve a local field theory which describes in terms of dual variables a system having an A μ propagator behaving like M 2 /q 4 in the infrared and discuss how this theory can be used as a starting point for describing long-distance QCD. 3 refs

Computation of mode eigenfunctions in graded-index optical fibers by the propagating beam method

International Nuclear Information System (INIS)

Feit, M.D.; Fleck, J.A. Jr.

1980-01-01

The propagating beam method utilizes discrete Fourier transforms for generating configuration-space solutions to optical waveguide problems without reference to modes. The propagating beam method can also give a complete description of the field in terms of modes by a Fourier analysis with respect to axial distance of the computed fields. Earlier work dealt with the accurate determination of mode propagation constants and group delays. In this paper the method is extended to the computation of mode eigenfunctions. The method is efficient, allowing generation of a large number of eigenfunctions from a single propagation run. Computations for parabolic-index profiles show excellent agreement between analytic and numerically generated eigenfunctions

Propagation of partially coherent Lorentz-Gauss vortex beam through oceanic turbulence.

Science.gov (United States)

Liu, Dajun; Yin, Hongming; Wang, Guiqiu; Wang, Yaochuan

2017-11-01

The partially coherent Lorentz-Gauss vortex beam generated by a Schell-model source has been introduced. Based on the extended Huygens-Fresnel principle, the cross-spectral density function of a partially coherent Lorentz-Gauss vortex beam propagating in oceanic turbulence is derived. The influences of coherence length, topological charge M, and oceanic turbulence on the spreading properties and position of the coherence vortex for a partially coherent Lorentz-Gauss vortex beam are analyzed in detail. The results show that a partially coherent Lorentz-Gauss vortex beam propagating in stronger oceanic turbulence will evolve into a Gaussian-like beam more rapidly as the propagation distance increases, and the number of coherent vortices will change.

Extremely Short Optical Pulses and Ads/CFT Compliance

Directory of Open Access Journals (Sweden)

Konobeeva N.N.

2015-01-01

Full Text Available Dynamics of few cycle optical pulses in non-Fermi liquid was considered. Energy spectrum of non-Fermi liquid was taken from the AdS/CFT compliance. Conditions of quasiparticle excitation existence were defined. Non-Fermi liquid parameters impact on the shape of few cycle pulses were estimated. It was shown that extremely short optical pulse propagation in the non-Fermi liquid is a stable pattern. The value of chemical potential has a significant impact on extremely short pulse shape. An increase in initial pulse amplitude does not result in pulse-shape distortions under its propagation in considered medium that is why the non-Fermi liquid can be used in applications inherent in extremely short pulse processing.

Ion Acoustic Waves in the Presence of Electron Plasma Waves

DEFF Research Database (Denmark)

Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

1977-01-01

Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave.......Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave....

Effect of race distance on muscle oxygenation in short-track speed skating.

Science.gov (United States)

Hesford, Catherine M; Laing, Stewart; Cardinale, Marco; Cooper, Chris E

2013-01-01

Previous work identified an asymmetry in tissue desaturation changes in the left and right quadriceps muscles during on-ice skating at maximal speed in males. The effect of changing race distance on the magnitude of desaturation or leg asymmetry is unknown. Six elite male skaters (age = 23 ± 1.8 yr, height = 1.8 ± 0.1 m, mass = 80.1 ± 5.7 kg, midthigh skinfold thickness = 7 ± 2 mm) and four elite female skaters (age = 21 ± 4 yr, height = 1.6 ± 0.1 m, mass = 65.2 ± 4.3 kg, midthigh skinfold thickness = 10 ± 1 mm) were studied. Subjects completed time trials over three race distances. Blood lactate concentration and O2 uptake measurements were combined with near-infrared spectroscopy measures of muscle oxygenation (TSI) and blood volume (tHb) in the right and left vastus lateralis. Neither race distance nor gender had a significant effect on the magnitude of maximal muscle desaturation (ΔTSI(max)). Pattern of local changes in tHb during individual laps was dependent upon subtle differences in skating technique used for the different race distances. Linear regression analysis revealed asymmetry between the right and left leg desaturation in males during the final stages of each race distance, but not in females. At all race distances, local muscle desaturation reached maximal values much more quickly than global VO(2peak). The use of wearable near-infrared spectroscopy devices enabled measurement of muscle oxygenation during competitive race simulation, thus providing unique insight into the effects of velocity and technique changes on local muscle oxygenation. This may have implications for training and race pacing in speed skating.

Excitation of accelerating plasma waves by counter-propagating laser beams

International Nuclear Information System (INIS)

Shvets, Gennady; Fisch, Nathaniel J.; Pukhov, Alexander

2002-01-01

The conventional approach to exciting high phase velocity waves in plasmas is to employ a laser pulse moving in the direction of the desired particle acceleration. Photon downshifting then causes momentum transfer to the plasma and wave excitation. Novel approaches to plasma wake excitation, colliding-beam accelerator (CBA), which involve photon exchange between the long and short counter-propagating laser beams, are described. Depending on the frequency detuning Δω between beams and duration τ L of the short pulse, there are two approaches to CBA. First approach assumes (τ L ≅2/ω p ). Photons exchanged between the beams deposit their recoil momentum in the plasma driving the plasma wake. Frequency detuning between the beams determines the direction of the photon exchange, thereby controlling the phase of the plasma wake. This phase control can be used for reversing the slippage of the accelerated particles with respect to the wake. A variation on the same theme, super-beatwave accelerator, is also described. In the second approach, a short pulse with τ L >>ω p -1 detuned by Δω∼2ω p from the counter-propagating beam is employed. While parametric excitation of plasma waves by the electromagnetic beatwave at 2ω p of two co-propagating lasers was first predicted by Rosenbluth and Liu [M. N. Rosenbluth and C. S. Liu, Phys. Rev. Lett. 29, 701 (1972)], it is demonstrated that the two excitation beams can be counter-propagating. The advantages of using this geometry (higher instability growth rate, insensitivity to plasma inhomogeneity) are explained, and supporting numerical simulations presented

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

International Nuclear Information System (INIS)

Palima, D; Tauro, S; Glückstad, J; Lindballe, T B; Kristensen, M V; Stapelfeldt, H; Keiding, S R

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-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 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 for optical trapping and manipulation using patterned counter-propagating beams, which still remains to be fully tapped

A rapid two step protocol of in vitro propagation of an important ...

African Journals Online (AJOL)

Attempts were made to evolve a rapid in vitro technology to conserve, as well as, mass propagate this valuable medicinal herb in very short duration. The combinations of ... MS media supplemented with BAP with IBA (4:0.5 and 5:0.5) resulted in shooting, as well as, rooting simultaneously. Micro propagated plantlets were ...

Crack propagation and the material removal mechanism of glass-ceramics by the scratch test.

Science.gov (United States)

Qiu, Zhongjun; Liu, Congcong; Wang, Haorong; Yang, Xue; Fang, Fengzhou; Tang, Junjie

2016-12-01

To eliminate the negative effects of surface flaws and subsurface damage of glass-ceramics on clinical effectiveness, crack propagation and the material removal mechanism of glass-ceramics were studied by single and double scratch experiments conducted using an ultra-precision machine. A self-manufactured pyramid shaped single-grit tool with a small tip radius was used as the scratch tool. The surface and subsurface crack propagations and interactions, surface morphology and material removal mechanism were investigated. The experimental results showed that the propagation of lateral cracks to the surface and the interaction between the lateral cracks and radial cracks are the two main types of material peeling, and the increase of the scratch depth increases the propagation angle of the radial cracks and the interaction between the cracks. In the case of a double scratch, the propagation of lateral cracks and radial cracks between paired scratches results in material peeling. The interaction between adjacent scratches depends on the scratch depth and separation distance. There is a critical separation distance where the normalized material removal volume reaches its peak. These findings can help reduce surface flaws and subsurface damage induced by the grinding process and improve the clinical effectiveness of glass-ceramics used as biological substitute and repair materials. Copyright © 2016 Elsevier Ltd. All rights reserved.

An aerodynamic noise propagation model for wind turbines

DEFF Research Database (Denmark)

Zhu, Wei Jun; Sørensen, Jens Nørkær; Shen, Wen Zhong

2005-01-01

A model based on 2-D sound ray theory for aerodynamic noise propagation from wind turbine rotating blades is introduced. The model includes attenuation factors from geometric spreading, sound directivity of source, air absorption, ground deflection and reflection, as well as effects from temperat......A model based on 2-D sound ray theory for aerodynamic noise propagation from wind turbine rotating blades is introduced. The model includes attenuation factors from geometric spreading, sound directivity of source, air absorption, ground deflection and reflection, as well as effects from...... temperature and airflow. At a given receiver point, the sound pressure is corrected by taking into account these propagation effects. As an overall assumption, the noise field generated by the wind turbine is simplified as a point source placed at the hub height of the wind turbine. This assumtion...... is reasonable, for the receiver is located in the far field, at distances from the wind turbine that are much longer than the diameter of the rotor....

Finite-Difference Time-Domain Simulation of Light Propagation in 2D Periodic and Quasi-Periodic Photonic Structures

Directory of Open Access Journals (Sweden)

N. Dadashzadeh

2013-09-01

Full Text Available Ultra-short pulse is a promising technology for achieving ultra-high data rate transmission which is required to follow the increased demand of data transport over an optical communication system. Therefore, the propagation of such type of pulses and the effects that it may suffer during its transmission through an optical waveguide has received a great deal of attention in the recent years. We provide an overview of recent theoretical developments in a numerical modeling of Maxwell's equations to analyze the propagation of short laser pulses in photonic structures. The process of short light pulse propagation through 2D periodic and quasi-periodic photonic structures is simulated based on Finite-Difference Time-Domain calculations of Maxwell’s equations.

Evaluation of Propagation Characteristics Using the Human Body as an Antenna.

Science.gov (United States)

Li, Jingzhen; Nie, Zedong; Liu, Yuhang; Wang, Lei; Hao, Yang

2017-12-11

In this paper, an inhomogeneous human body model was presented to investigate the propagation characteristics when the human body was used as an antenna to achieve signal transmission. Specifically, the channel gain of four scenarios, namely, (1) both TX electrode and RX electrode were placed in the air, (2) TX electrode was attached on the human body, and RX electrode was placed in the air, (3) TX electrode was placed in the air, and RX electrode was attached on the human body, (4) both the TX electrode and RX electrode were attached on the human body, were studied through numerical simulation in the frequency range 1 MHz to 90 MHz. Furthermore, the comparisons of input efficiency, accepted efficiency, total efficiency, absorption power of human body, and electric field distribution of different distances of four aforementioned scenarios were explored when the frequency was at 44 MHz. In addition, the influences of different human tissues, electrode position, and the distance between electrode and human body on the propagation characteristics were investigated respectively at 44 MHz. The results showed that the channel gain of Scenario 4 was the maximum when the frequency was from 1 MHz to 90 MHz. The propagation characteristics were almost independent of electrode position when the human body was using as an antenna. However, as the distance between TX electrode and human body increased, the channel gain decreased rapidly. The simulations were verified by experimental measurements. The results showed that the simulations were in agreement with the measurements.

Musing on the Memes of Open and Distance Education

Science.gov (United States)

Latchem, Colin

2014-01-01

Just as genes propagate themselves in the gene pool by leaping from body to body, so memes (ideas, behaviours, and actions) transmit cultural ideas or practices from one mind to another through writing, speech, or other imitable phenomena. This paper considers the memes that influence the evolution of open and distance education. If the…

On short cracks that depart from elastoplastic notch tips

Directory of Open Access Journals (Sweden)

Verônica Miquelin Machado

2017-07-01

Full Text Available The behavior of short cracks that depart from elastoplastic notch tips is modeled to estimate the stresses required to initiate and to propagate cracks in notched structural components, and to evaluate the size of tolerable crack-like defects under general loading conditions. This analysis can model both fatigue and environmentally assisted cracking problems; can evaluate notch sensitivity in both cases; and can as well be used to establish design or acceptance criteria for tolerable non-propagating crack-like defects in such cases. The growth of short cracks is assumed driven by the applied stresses and by the stress gradient ahead the notch tip, and supported by the material resistances to crack initiation and to long crack propagation by fatigue or EAC. In the elastoplastic case, the stress gradient ahead of the notch tip is quantified by a J-field to consider the short crack behavior. The tolerable short crack predictions made by this model are evaluated by suitable fatigue and EAC tests of notched specimens specially designed to start nonpropagating cracks from the notch tips, both under elastic and elastoplastic conditions.

Phenomenological dynamics in QCD at large distances

International Nuclear Information System (INIS)

Gogohia, V.Sh.; Kluge, Gy.

1991-07-01

A gauge-invariant, nonperturbative approach to QCD at large distances in the context of the Schwinger-Dyson equations and corresponding Slavnov-Taylor identities in the quark sector is presented. Making only one widely accepted assumption that the full gluon propagator becomes an infrared singular like (q 2 ) -2 in the covariant gauge, we find three and only three confinement-type solutions for the quark propagator (quark confinement theorem.) The approach is free from ghost complications. Also show that multiplication by the quark infrared renormalization constant only, would make all the Green's functions infrared finite (multiplicative renormalizability). The bound-state problem in framework of Bethe-Salpeter equation is discussed as well. Some basic physical parameters of chiral QCD as pion decay constant and quark condensate, have been calculated within our approach. (author) 75 refs.; 14 figs

Electron thermal conductivity from heat wave propagation in Wendelstein 7-AS

Energy Technology Data Exchange (ETDEWEB)

Giannone, L.; Erckmann, V; Gasparino, U; Hartfuss, H J; Kuehner, G; Maassberg, H; Stroth, U; Tutter, M [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); W7-AS Team; ECRH Group IPF Stuttgart; Gyrotron Group KFK Karlsruhe

1992-11-01

Heat wave propagation experiments have been carried out on the Wendelstein 7-AS stellarator. The deposition of electron cyclotron resonance heating power is highly localized in the plasma centre, so that power modulation produces heat waves which propagate away from the deposition volume. Radiometry of the electron cyclotron emission is used to measure the generated temperature perturbation. The propagation time delay of the temperature perturbation as a function of distance to the power deposition region is used to determine the electron thermal conductivity [chi][sub e]. This value is then compared with the value determined by global power balance. In contrast to sawtooth propagation experiments in tokamaks, it is found that the value of [chi][sub e] from heat wave propagation is comparable to that calculated by power balance. In addition, inward propagating waves were produced by choosing a power deposition region away from the plasma centre. Experiments were carried out at 70 GHz in the ordinary mode and at 140 GHz in the extraordinary mode. Variations of the modulation power amplitude have demonstrated that the inferred value of [chi][sub e] is independent of the amplitude of the induced temperature perturbations. (author). 29 refs, 11 figs, 5 tabs.

Optical Propagation Modeling for the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Williams, W H; Auerbach, J M; Henesian, M A; Jancaitis, K S; Manes, K R; Mehta, N C; Orth, C D; Sacks, R A; Shaw, M J; Widmayer, C C

2004-01-12

Optical propagation modeling of the National Ignition Facility has been utilized extensively from conceptual design several years ago through to early operations today. In practice we routinely (for every shot) model beam propagation starting from the waveform generator through to the target. This includes the regenerative amplifier, the 4-pass rod amplifier, and the large slab amplifiers. Such models have been improved over time to include details such as distances between components, gain profiles in the laser slabs and rods, transient optical distortions due to the flashlamp heating of laser slabs, measured transmitted and reflected wavefronts for all large optics, the adaptive optic feedback loop, and the frequency converter. These calculations allow nearfield and farfield predictions in good agreement with measurements.

Study on the propagation properties of laser in aerosol based on Monte Carlo simulation

Science.gov (United States)

Leng, Kun; Wu, Wenyuan; Zhang, Xi; Gong, Yanchun; Yang, Yuntao

2018-02-01

When laser propagate in the atmosphere, due to aerosol scattering and absorption, laser energy will continue to decline, affecting the effectiveness of the laser effect. Based on the Monte Carlo method, the relationship between the photon spatial energy distributions of the laser wavelengths of 10.6μm in marine, sand-type, water-soluble and soot aerosols ,and the propagation distance, visibility and the divergence angle were studied. The results show that for 10.6μm laser, the maximum number of attenuation of photons arriving at the receiving plane is sand-type aerosol, the minimal attenuation is water soluble aerosol; as the propagation distance increases, the number of photons arriving at the receiving plane decreases; as the visibility increases, the number of photons arriving at the receiving plane increases rapidly and then stabilizes; in the above cases, the photon energy distribution does not deviated from the Gaussian distribution; as the divergence angle increases, the number of photons arriving at the receiving plane is almost unchanged, but the photon energy distribution gradually deviates from the Gaussian distribution.

Understanding pyrotechnic shock dynamics and response attenuation over distance

Science.gov (United States)

Ott, Richard J.

Pyrotechnic shock events used during stage separation on rocket vehicles produce high amplitude short duration structural response that can lead to malfunction or degradation of electronic components, cracks and fractures in brittle materials, local plastic deformation, and can cause materials to experience accelerated fatigue life. These transient loads propagate as waves through the structural media losing energy as they travel outward from the source. This work assessed available test data in an effort to better understand attenuation characteristics associated with wave propagation and attempted to update a historical standard defined by the Martin Marietta Corporation in the late 1960's using out of date data acquisition systems. Two data sets were available for consideration. The first data set came from a test that used a flight like cylinder used in NASA's Ares I-X program, and the second from a test conducted with a flat plate. Both data sets suggested that the historical standard was not a conservative estimate of shock attenuation with distance, however, the variation in the test data did not lend to recommending an update to the standard. Beyond considering attenuation with distance an effort was made to model the flat plate configuration using finite element analysis. The available flat plate data consisted of three groups of tests, each with a unique charge density linear shape charge (LSC) used to cut an aluminum plate. The model was tuned to a representative test using the lowest charge density LSC as input. The correlated model was then used to predict the other two cases by linearly scaling the input load based on the relative difference in charge density. The resulting model predictions were then compared with available empirical data. Aside from differences in amplitude due to nonlinearities associated with scaling the charge density of the LSC, the model predictions matched the available test data reasonably well. Finally, modeling best

Calculation of nuclear electromagnetic pulse propagation along the earth's surface

International Nuclear Information System (INIS)

Liang Rui; Zheng Yi; Song Lijun; Zhang Xueqin; Lip Peng

2010-01-01

It calculates the LF/VLF wave of NEMP propagation along the earth's surface. The earth-wave and the sky-wave are taken into account in the calculation. With the distance increase, the earth wave attenuates fast than the sky wave, and the time difference between the earth wave and the sky wave is reduced. (authors)

Site-to-Source Finite Fault Distance Probability Distribution in Probabilistic Seismic Hazard and the Relationship Between Minimum Distances

Science.gov (United States)

Ortega, R.; Gutierrez, E.; Carciumaru, D. D.; Huesca-Perez, E.

2017-12-01

We present a method to compute the conditional and no-conditional probability density function (PDF) of the finite fault distance distribution (FFDD). Two cases are described: lines and areas. The case of lines has a simple analytical solution while, in the case of areas, the geometrical probability of a fault based on the strike, dip, and fault segment vertices is obtained using the projection of spheres in a piecewise rectangular surface. The cumulative distribution is computed by measuring the projection of a sphere of radius r in an effective area using an algorithm that estimates the area of a circle within a rectangle. In addition, we introduce the finite fault distance metrics. This distance is the distance where the maximum stress release occurs within the fault plane and generates a peak ground motion. Later, we can apply the appropriate ground motion prediction equations (GMPE) for PSHA. The conditional probability of distance given magnitude is also presented using different scaling laws. A simple model of constant distribution of the centroid at the geometrical mean is discussed, in this model hazard is reduced at the edges because the effective size is reduced. Nowadays there is a trend of using extended source distances in PSHA, however it is not possible to separate the fault geometry from the GMPE. With this new approach, it is possible to add fault rupture models separating geometrical and propagation effects.

Theoretical Model of Acoustic Wave Propagation in Shallow Water

Directory of Open Access Journals (Sweden)

Kozaczka Eugeniusz

2017-06-01

Full Text Available The work is devoted to the propagation of low frequency waves in a shallow sea. As a source of acoustic waves, underwater disturbances generated by ships were adopted. A specific feature of the propagation of acoustic waves in shallow water is the proximity of boundaries of the limiting media characterised by different impedance properties, which affects the acoustic field coming from a source situated in the water layer “deformed” by different phenomena. The acoustic field distribution in the real shallow sea is affected not only by multiple reflections, but also by stochastic changes in the free surface shape, and statistical changes in the seabed shape and impedance. The paper discusses fundamental problems of modal sound propagation in the water layer over different types of bottom sediments. The basic task in this case was to determine the acoustic pressure level as a function of distance and depth. The results of the conducted investigation can be useful in indirect determination of the type of bottom.

A calculation method of the optimal distance of the long-drawn short-pressure type localfan in minebased on the principle of the jet and Suction volume

Science.gov (United States)

Fu, Shaotong

2018-01-01

In order to dilute the harmful smoke and dust of the working surface in the production of the roadway in the mine shaft, the combination of mine local ventilation is often considered when conditions permitting. However there is no definite method to determine the distance between fan and working surface. Considering the concentration of smoke, the size of working face, the ventilation time, the wind speed of the working face and the principle of suction volume, this paper analyzes the long - drawn short - pressure type of the ventilation scheme, and presents an optimal algorithm for the distance between the exhaust ventilator and the working face:{{L}}{{o}}=\\frac{{({{{v}}}{{f}}{{t}})}{{Z}}{{{S}}}{{o}}\\frac{\\exists }{{{z}}{{β }}}}{3.398{{{S}}}W\\frac{1}{{{z}}{{A}}}}. Then this paperpresentsa reference distance for different wind speed requirements of a project.

Large scale propagation intermittency in the atmosphere

Science.gov (United States)

Mehrabi, Ali

2000-11-01

Long-term (several minutes to hours) amplitude variations observed in outdoor sound propagation experiments at Disneyland, California, in February 1998 are explained in terms of a time varying index of refraction. The experimentally propagated acoustic signals were received and recorded at several locations ranging from 300 meters to 2,800 meters. Meteorological data was taken as a function of altitude simultaneously with the received signal levels. There were many barriers along the path of acoustic propagation that affected the received signal levels, especially at short ranges. In a downward refraction situation, there could be a random change of amplitude in the predicted signals. A computer model based on the Fast Field Program (FFP) was used to compute the signal loss at the different receiving locations and to verify that the variations in the received signal levels can be predicted numerically. The calculations agree with experimental data with the same trend variations in average amplitude.

Operational Decision Aids for Exploiting or Mitigating Electromagnetic Propagation Effects

Science.gov (United States)

1989-09-01

tous las pas suivants en distance, ce qui conduit 8 une atmosphere homo- gene dans le sens de la propagation) at l’atmosphtre relle obtenue par les...Europe occidentele 36-14 Niveau (db) Niveau (dbm) -40 8 -78 -68 -778 wo -140 a) Fanc F(M~z) b) Tahiti Polyn6sie francaise Figure 8 Comparaison de

Propagation of aortic dissection and visceral artery compromise. Three-dimensional analysis on CT angiography

International Nuclear Information System (INIS)

Minamiguchi, Hiroki

2003-01-01

The purpose of this study was to clarify the patterns of the propagation of aortic dissection with quantitative data from CT angiography and to verify the relationship between the propagation of aortic dissection and visceral artery compromise. The subjects were 67 cases (48 men, 19 women) with acute and subacute aortic dissection extending from the descending thoracic aorta to the aortic bifurcation. The mean age is 56.5±12.3 years old (range 34 to 80 years). Eight axial levels of the trunk of right pulmonary artery, left inferior pulmonary vein, coronary sinus, celiac axis, the orifice of superior mesenteric artery (SMA), the orifice of right real artery, the orifice of left renal artery and the orifice of inferior mesenteric artery were submitted to investigate the propagation of aortic dissection. The true lumen central angle was calculated in each level. The axial distance, branch angle difference and true distance between SMA and bilateral renal arteries were calculated. The trajectory of aortic dissection propagation from descending thoracic aorta to aortic bifurcation could be divided into two types of linear dissection type (n=41) and spiral dissection type (n=26). The latter were further subdivided into clockwise rotation type (n=14) and counter-clockwise rotation type (n=12). Younger age was significantly associated with the spiral dissection type as compared to older age (p=0.030). The spiral dissection type propagation pattern was found predominantly from the descending thoracic aorta to celiac axis, while at more distal levels linear type dissection was more common. The blood flow of SMA and celiac axis came from the true lumen or both lumens in all cases but single case from false lumen. The incidence (19.4%) of the right renal blood flow supplied from false lumen was lower than that (37.3%) of the left one supplied from false lumen. The shorter distance and the less angle difference between SMA and right renal artery than between SMA and left renal

Studies of nonlinear ultrasound propagation: safety considerations in the use of ultrasound for medical diagnosis - nonlinear propagation

International Nuclear Information System (INIS)

Egerton, B.; Barnett, S.; Vella, G.

1994-01-01

Diagnostic ultrasound is an established imaging modality without any documented harmful effects. New developments such as pulsed Doppler and intracavity investigations may result in increases in ultrasound exposures which could cause harm. Thermal mechanisms and cavitation may become relevant sources of bioeffects. The preliminary study described here investigates the distribution and amplitude of harmonics generated through nonlinear propagation of ultrasound in water. Knowledge of harmonic attenuation will help predict sites of enhanced heating and enable accurate modelling of clinical situations. This presentation is concerned with thermal safety guidelines, their relationship to a typical ultrasound beam profile for a single, medium focussed, transducer operating in water and possible sites of enhanced heating due to nonlinear propagation effects. Measurements were made of the amplitudes of the harmonics generated by the nonlinear propagation of ultrasound in water. The amplitudes of the harmonics were detected up to frequencies of 35 MHz and displayed using Fast Fourier Transform facilities within the oscilloscope. The nonlinearity parameter of the ultrasonic waveforms has been identified as an important factor in thermal effects of ultrasound interactions. The appearance of nonlinear distortion is shown to be dependant on the peak compressional pressure and distance from the ultrasound source. 20 refs., 2 figs

Propagation of electromagnetic radiation in a random field of gravitational waves and space radio interferometry

International Nuclear Information System (INIS)

Braginsky, V.B.; Kardashev, N.S.; Polnarev, A.G.; Novikov, I.D.

1989-12-01

Propagation of an electromagnetic wave in the field of gravitational waves is considered. Attention is given to the principal difference between the electromagnetic wave propagation in the field of random gravitational waves and the electromagnetic wave propagation in a medium with a randomly-inhomogeneous refraction index. It is shown that in the case of the gravitation wave field the phase shift of an electromagnetic wave does not increase with distance. The capability of space radio interferometry to detect relic gravitational waves as well as gravitational wave bursts of non cosmological origin are analyzed. (author). 64 refs, 2 figs

Demand, propagation and seedling establishment of selected medicinal trees

CSIR Research Space (South Africa)

Netshiluvhi, TR

1999-12-01

Full Text Available Short-listing of medicinal tree species for propagation was done through three criteria; number of bags sold, price per bag and mean scarcity value. There is a strong correlation between the mean scarcity values and number of bags sold per annum...

X-ray propagation through a quasi-ordered multilayered structure ...

African Journals Online (AJOL)

We investigate the propagation of short wavelength transverse electric x-rays through a quasiordered (Fibonacci) atomically commensurate multilayered structure using a transfer matrix model which treats each atomic plane as a diffraction unit. The reflectance spectrum has a rich structure being dominated by peaks ...

Time domain simulation of Gd3+-Gd3+ distance measurements by EPR

Science.gov (United States)

Manukovsky, Nurit; Feintuch, Akiva; Kuprov, Ilya; Goldfarb, Daniella

2017-07-01

Gd3+-based spin labels are useful as an alternative to nitroxides for intramolecular distance measurements at high fields in biological systems. However, double electron-electron resonance (DEER) measurements using model Gd3+ complexes featured a low modulation depth and an unexpected broadening of the distance distribution for short Gd3+-Gd3+ distances, when analysed using the software designed for S = 1/2 pairs. It appears that these effects result from the different spectroscopic characteristics of Gd3+—the high spin, the zero field splitting (ZFS), and the flip-flop terms in the dipolar Hamiltonian that are often ignored for spin-1/2 systems. An understanding of the factors affecting the modulation frequency and amplitude is essential for the correct analysis of Gd3+-Gd3+ DEER data and for the educated choice of experimental settings, such as Gd3+ spin label type and the pulse parameters. This work uses time-domain simulations of Gd3+-Gd3+ DEER by explicit density matrix propagation to elucidate the factors shaping Gd3+ DEER traces. The simulations show that mixing between the |+½, -½> and |-½, +½> states of the two spins, caused by the flip-flop term in the dipolar Hamiltonian, leads to dampening of the dipolar modulation. This effect may be mitigated by a large ZFS or by pulse frequency settings allowing for a decreased contribution of the central transition and the one adjacent to it. The simulations reproduce both the experimental line shapes of the Fourier-transforms of the DEER time domain traces and the trends in the behaviour of the modulation depth, thus enabling a more systematic design and analysis of Gd3+ DEER experiments.

Model for small arms fire muzzle blast wave propagation in air

Science.gov (United States)

Aguilar, Juan R.; Desai, Sachi V.

2011-11-01

Accurate modeling of small firearms muzzle blast wave propagation in the far field is critical to predict sound pressure levels, impulse durations and rise times, as functions of propagation distance. Such a task being relevant to a number of military applications including the determination of human response to blast noise, gunfire detection and localization, and gun suppressor design. Herein, a time domain model to predict small arms fire muzzle blast wave propagation is introduced. The model implements a Friedlander wave with finite rise time which diverges spherically from the gun muzzle. Additionally, the effects in blast wave form of thermoviscous and molecular relaxational processes, which are associated with atmospheric absorption of sound were also incorporated in the model. Atmospheric absorption of blast waves is implemented using a time domain recursive formula obtained from numerical integration of corresponding differential equations using a Crank-Nicholson finite difference scheme. Theoretical predictions from our model were compared to previously recorded real world data of muzzle blast wave signatures obtained by shooting a set different sniper weapons of varying calibers. Recordings containing gunfire acoustical signatures were taken at distances between 100 and 600 meters from the gun muzzle. Results shows that predicted blast wave slope and exponential decay agrees well with measured data. Analysis also reveals the persistency of an oscillatory phenomenon after blast overpressure in the recorded wave forms.

Uncertainty propagation in probabilistic safety analysis of nuclear power plants

International Nuclear Information System (INIS)

Fleming, P.V.

1981-09-01

The uncertainty propagation in probabilistic safety analysis of nuclear power plants, is done. The methodology of the minimal cut is implemented in the computer code SVALON and the results for several cases are compared with corresponding results obtained with the SAMPLE code, which employs the Monte Carlo method to propagate the uncertanties. The results have show that, for a relatively small number of dominant minimal cut sets (n approximately 25) and error factors (r approximately 5) the SVALON code yields results which are comparable to those obtained with SAMPLE. An analysis of the unavailability of the low pressure recirculation system of Angra 1 for both the short and long term recirculation phases, are presented. The results for the short term phase are in good agreement with the corresponding one given in WASH-1400. (E.G.) [pt

A Comparative Evaluation of 3 Different Free-Form Deformable Image Registration and Contour Propagation Methods for Head and Neck MRI: The Case of Parotid Changes During Radiotherapy.

Science.gov (United States)

Broggi, Sara; Scalco, Elisa; Belli, Maria Luisa; Logghe, Gerlinde; Verellen, Dirk; Moriconi, Stefano; Chiara, Anna; Palmisano, Anna; Mellone, Renata; Fiorino, Claudio; Rizzo, Giovanna

2017-06-01

To validate and compare the deformable image registration and parotid contour propagation process for head and neck magnetic resonance imaging in patients treated with radiotherapy using 3 different approaches-the commercial MIM, the open-source Elastix software, and an optimized version of it. Twelve patients with head and neck cancer previously treated with radiotherapy were considered. Deformable image registration and parotid contour propagation were evaluated by considering the magnetic resonance images acquired before and after the end of the treatment. Deformable image registration, based on free-form deformation method, and contour propagation available on MIM were compared to Elastix. Two different contour propagation approaches were implemented for Elastix software, a conventional one (DIR_Trx) and an optimized homemade version, based on mesh deformation (DIR_Mesh). The accuracy of these 3 approaches was estimated by comparing propagated to manual contours in terms of average symmetric distance, maximum symmetric distance, Dice similarity coefficient, sensitivity, and inclusiveness. A good agreement was generally found between the manual contours and the propagated ones, without differences among the 3 methods; in few critical cases with complex deformations, DIR_Mesh proved to be more accurate, having the lowest values of average symmetric distance and maximum symmetric distance and the highest value of Dice similarity coefficient, although nonsignificant. The average propagation errors with respect to the reference contours are lower than the voxel diagonal (2 mm), and Dice similarity coefficient is around 0.8 for all 3 methods. The 3 free-form deformation approaches were not significantly different in terms of deformable image registration accuracy and can be safely adopted for the registration and parotid contour propagation during radiotherapy on magnetic resonance imaging. More optimized approaches (as DIR_Mesh) could be preferable for critical

Discovery of the short gamma-ray burst GRB 050709.

Science.gov (United States)

Villasenor, J S; Lamb, D Q; Ricker, G R; Atteia, J-L; Kawai, N; Butler, N; Nakagawa, Y; Jernigan, J G; Boer, M; Crew, G B; Donaghy, T Q; Doty, J; Fenimore, E E; Galassi, M; Graziani, C; Hurley, K; Levine, A; Martel, F; Matsuoka, M; Olive, J-F; Prigozhin, G; Sakamoto, T; Shirasaki, Y; Suzuki, M; Tamagawa, T; Vanderspek, R; Woosley, S E; Yoshida, A; Braga, J; Manchanda, R; Pizzichini, G; Takagishi, K; Yamauchi, M

2005-10-06

Gamma-ray bursts (GRBs) fall into two classes: short-hard and long-soft bursts. The latter are now known to have X-ray and optical afterglows, to occur at cosmological distances in star-forming galaxies, and to be associated with the explosion of massive stars. In contrast, the distance scale, the energy scale and the progenitors of the short bursts have remained a mystery. Here we report the discovery of a short-hard burst whose accurate localization has led to follow-up observations that have identified the X-ray afterglow and (for the first time) the optical afterglow of a short-hard burst; this in turn led to the identification of the host galaxy of the burst as a late-type galaxy at z = 0.16 (ref. 10). These results show that at least some short-hard bursts occur at cosmological distances in the outskirts of galaxies, and are likely to be caused by the merging of compact binaries.

Long, partial-short, and special conformal fields

Energy Technology Data Exchange (ETDEWEB)

Metsaev, R.R. [Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky prospect 53, Moscow 119991 (Russian Federation)

2016-05-17

In the framework of metric-like approach, totally symmetric arbitrary spin bosonic conformal fields propagating in flat space-time are studied. Depending on the values of conformal dimension, spin, and dimension of space-time, we classify all conformal field as long, partial-short, short, and special conformal fields. An ordinary-derivative (second-derivative) Lagrangian formulation for such conformal fields is obtained. The ordinary-derivative Lagrangian formulation is realized by using double-traceless gauge fields, Stueckelberg fields, and auxiliary fields. Gauge-fixed Lagrangian invariant under global BRST transformations is obtained. The gauge-fixed BRST Lagrangian is used for the computation of partition functions for all conformal fields. Using the result for the partition functions, numbers of propagating D.o.F for the conformal fields are also found.

Observation of quasi-periodic solar radio bursts associated with propagating fast-mode waves

Science.gov (United States)

Goddard, C. R.; Nisticò, G.; Nakariakov, V. M.; Zimovets, I. V.; White, S. M.

2016-10-01

Aims: Radio emission observations from the Learmonth and Bruny Island radio spectrographs are analysed to determine the nature of a train of discrete, periodic radio "sparks" (finite-bandwidth, short-duration isolated radio features) which precede a type II burst. We analyse extreme ultraviolet (EUV) imaging from SDO/AIA at multiple wavelengths and identify a series of quasi-periodic rapidly-propagating enhancements, which we interpret as a fast wave train, and link these to the detected radio features. Methods: The speeds and positions of the periodic rapidly propagating fast waves and the coronal mass ejection (CME) were recorded using running-difference images and time-distance analysis. From the frequency of the radio sparks the local electron density at the emission location was estimated for each. Using an empirical model for the scaling of density in the corona, the calculated electron density was used to obtain the height above the surface at which the emission occurs, and the propagation velocity of the emission location. Results: The period of the radio sparks, δtr = 1.78 ± 0.04 min, matches the period of the fast wave train observed at 171 Å, δtEUV = 1.7 ± 0.2 min. The inferred speed of the emission location of the radio sparks, 630 km s-1, is comparable to the measured speed of the CME leading edge, 500 km s-1, and the speeds derived from the drifting of the type II lanes. The calculated height of the radio emission (obtained from the density) matches the observed location of the CME leading edge. From the above evidence we propose that the radio sparks are caused by the quasi-periodic fast waves, and the emission is generated as they catch up and interact with the leading edge of the CME. The movie associated to Fig. 2 is available at http://www.aanda.org

Studies of infrasound propagation using the USArray seismic network (Invited)

Science.gov (United States)

Hedlin, M. A.; Degroot-Hedlin, C. D.; Walker, K. T.

2010-12-01

Although there are currently ~ 100 infrasound arrays worldwide, more than ever before, the station density is still insufficient to provide validation for detailed propagation modeling. Much structure in the atmosphere is short-lived and occurs at spatial scales much smaller than the average distance between infrasound stations. Relatively large infrasound signals can be observed on seismic channels due to coupling at the Earth's surface. Recent research, using data from the 70-km spaced 400-station USArray and other seismic network deployments, has shown the value of dense seismic network data for filling in the gaps between infrasound arrays. The dense sampling of the infrasound wavefield has allowed us to observe complete travel-time branches of infrasound signals and shed more light on the nature of infrasound propagation. We present early results from our studies of impulsive atmospheric sources, such as series of UTTR rocket motor detonations in Utah. The Utah blasts have been well recorded by USArray seismic stations and infrasound arrays in Nevada and Washington State. Recordings of seismic signals from a series of six events in 2007 are used to pinpoint the shot times to < 1 second. Variations in the acoustic branches and signal arrival times at the arrays are used to probe variations in atmospheric structure. Although we currently use coupled signals we anticipate studying dense acoustic network recordings as the USArray is currently being upgraded with infrasound microphones. These new sensors will allow us to make semi-continental scale network recordings of infrasound signals free of concerns about how the signals observed on seismic channels were modified when being coupled to seismic.

Gesture Interaction at a Distance

NARCIS (Netherlands)

Fikkert, F.W.

2010-01-01

The aim of this work is to explore, from a perspective of human behavior, which gestures are suited to control large display surfaces from a short distance away; why that is so; and, equally important, how such an interface can be made a reality. A well-known example of the type of interface that is

On the quark-antiquark potential at short distances

International Nuclear Information System (INIS)

Altevogt, P.

1994-12-01

We investigate the static quark-antiquark potential up to distances of 8 lattice units for pure SU(2) gauge theory on lattices with anisotropic couplings. The action is the Wilson action with a coupling fro time-like plaquettes which differs from those for space-like ones. Numerical simulations are performed in a large range of β. The potential is obtained by fitting 'cooled' Wilson loops with up to 4 exponential terms. An interpolation of the potentials by a sum of a perturbative term, a linear term and by lattice artifacts shows poor scaling in comparison with the isotropic case. If the coupling in the time-like region is reduced, the linear term is much smaller than in the isotropic case, and vice versa. Consequences for the bag picture for hadrons are discussed. (orig.)

Impact of wave propagation delay on latency in optical communication systems

Science.gov (United States)

Kawanishi, Tetsuya; Kanno, Atsushi; Yoshida, Yuki; Kitayama, Ken-ichi

2012-12-01

Latency is an important figure to describe performance of transmission systems for particular applications, such as data transfer for earthquake early warning, transaction for financial businesses, interactive services such as online games, etc. Latency consists of delay due to signal processing at nodes and transmitters, and of signal propagation delay due to propagation of electromagnetic waves. The lower limit of the latency in transmission systems using conventional single mode fibers (SMFs) depends on wave propagation speed in the SMFs which is slower than c. Photonic crystal fibers, holly fibers and large core fibers can have low effective refractive indices, and can transfer light faster than in SMFs. In free-space optical systems, signals propagate with the speed c, so that the latency could be smaller than in optical fibers. For example, LEO satellites would transmit data faster than optical submarine cables, when the transmission distance is longer than a few thousand kilometers. This paper will discuss combination of various transmission media to reduce negative impact of the latency, as well as applications of low-latency systems.

Propagation of coherent light pulses with PHASE

Science.gov (United States)

Bahrdt, J.; Flechsig, U.; Grizzoli, W.; Siewert, F.

2014-09-01

The current status of the software package PHASE for the propagation of coherent light pulses along a synchrotron radiation beamline is presented. PHASE is based on an asymptotic expansion of the Fresnel-Kirchhoff integral (stationary phase approximation) which is usually truncated at the 2nd order. The limits of this approximation as well as possible extensions to higher orders are discussed. The accuracy is benchmarked against a direct integration of the Fresnel-Kirchhoff integral. Long range slope errors of optical elements can be included by means of 8th order polynomials in the optical element coordinates w and l. Only recently, a method for the description of short range slope errors has been implemented. The accuracy of this method is evaluated and examples for realistic slope errors are given. PHASE can be run either from a built-in graphical user interface or from any script language. The latter method provides substantial flexibility. Optical elements including apertures can be combined. Complete wave packages can be propagated, as well. Fourier propagators are included in the package, thus, the user may choose between a variety of propagators. Several means to speed up the computation time were tested - among them are the parallelization in a multi core environment and the parallelization on a cluster.

SimProp: a simulation code for ultra high energy cosmic ray propagation

International Nuclear Information System (INIS)

Aloisio, R.; Grillo, A.F.; Boncioli, D.; Petrera, S.; Salamida, F.

2012-01-01

A new Monte Carlo simulation code for the propagation of Ultra High Energy Cosmic Rays is presented. The results of this simulation scheme are tested by comparison with results of another Monte Carlo computation as well as with the results obtained by directly solving the kinetic equation for the propagation of Ultra High Energy Cosmic Rays. A short comparison with the latest flux published by the Pierre Auger collaboration is also presented

Fundamental design of a distributed erbium-doped fiber amplifier for long-distance transmission

DEFF Research Database (Denmark)

Rottwitt, Karsten; Bjarklev, Anders Overgaard; Povlsen, Jørn Hedegaard

1992-01-01

. Designs based on a bidirectional pumping scheme are evaluated, taking nonlinearities into account. The optimum value of the numerical aperture will be evaluated for cutoff wavelengths where the propagating pump power is single moded. For distances between each pumping station in the region between 10...

Propagation of Channel Plasmons at the Visible Regime in Aluminum V-Groove Waveguides

DEFF Research Database (Denmark)

Lotan, Oren; Smith, Cameron; Bar-David, Jonathan

2016-01-01

Aluminum plasmonics is emerging as a promising platform in particular for the ultraviolet-blue spectral band. We present the experimental results of propagating channel plasmon-polaritons (CPP) waves in aluminum coated V-shaped waveguides at the short visible wavelength regime. The V-grooves are ......Aluminum plasmonics is emerging as a promising platform in particular for the ultraviolet-blue spectral band. We present the experimental results of propagating channel plasmon-polaritons (CPP) waves in aluminum coated V-shaped waveguides at the short visible wavelength regime. The V......-grooves are fabricated by a process involving UV-photolithography, crystallographic silicon etching, and metal deposition. Polarization measurements of coupling demonstrate a preference to the TM-aligned mode, as predicted in simulations....

Propagation Path Loss Models for 5G Urban Micro- and Macro-Cellular Scenarios

DEFF Research Database (Denmark)

Sun, Shu; Rappaport, Theodore S.; Rangan, Sundeep

2016-01-01

This paper presents and compares two candidate large-scale propagation path loss models, the alpha-beta-gamma (ABG) model and the close-in (CI) free space reference distance model, for the design of fifth generation (5G) wireless communication systems in urban micro- and macro-cellular scenarios....

Vortex instability in turbulent free-space propagation

Science.gov (United States)

Lavery, Martin P. J.

2018-04-01

The spatial structuring of optical fields is integral within many next generation optical metrology and communication techniques. A verifiable physical model of the propagation of these optical fields in a turbulent environment is important for developing effective mitigation techniques for the modal degradation that occurs in a free-space link. We present a method to simulate this modal degradation that agrees with recently reported experimental findings. A 1.5 km free-space link is emulated by decomposing the optical turbulence that accumulates over a long distance link, into many, weakly perturbing steps of 10 m. This simulation shows that the high-order vortex at the centre of the helical phase profiles in modes that carry orbital angular momentum of | {\\ell }| ≥slant 2{\\hslash } are unstable and fracture into many vortices when they propagate over the link. This splitting presents issues for the application of turbulence mitigation techniques. The usefulness of pre-correction, post-correction, and complex field conjugation techniques are discussed.

An improved empirical model for diversity gain on Earth-space propagation paths

Science.gov (United States)

Hodge, D. B.

1981-01-01

An empirical model was generated to estimate diversity gain on Earth-space propagation paths as a function of Earth terminal separation distance, link frequency, elevation angle, and angle between the baseline and the path azimuth. The resulting model reproduces the entire experimental data set with an RMS error of 0.73 dB.

Edit propagation using geometric relationship functions

KAUST Repository

Guerrero, Paul; Jeschke, Stefan; Wimmer, Michael; Wonka, Peter

2014-01-01

We propose a method for propagating edit operations in 2D vector graphics, based on geometric relationship functions. These functions quantify the geometric relationship of a point to a polygon, such as the distance to the boundary or the direction to the closest corner vertex. The level sets of the relationship functions describe points with the same relationship to a polygon. For a given query point, we first determine a set of relationships to local features, construct all level sets for these relationships, and accumulate them. The maxima of the resulting distribution are points with similar geometric relationships. We show extensions to handle mirror symmetries, and discuss the use of relationship functions as local coordinate systems. Our method can be applied, for example, to interactive floorplan editing, and it is especially useful for large layouts, where individual edits would be cumbersome. We demonstrate populating 2D layouts with tens to hundreds of objects by propagating relatively few edit operations. © 2014 ACM 0730-0301/2014/03- ART15 $15.00.

Edit propagation using geometric relationship functions

KAUST Repository

Guerrero, Paul

2014-04-15

We propose a method for propagating edit operations in 2D vector graphics, based on geometric relationship functions. These functions quantify the geometric relationship of a point to a polygon, such as the distance to the boundary or the direction to the closest corner vertex. The level sets of the relationship functions describe points with the same relationship to a polygon. For a given query point, we first determine a set of relationships to local features, construct all level sets for these relationships, and accumulate them. The maxima of the resulting distribution are points with similar geometric relationships. We show extensions to handle mirror symmetries, and discuss the use of relationship functions as local coordinate systems. Our method can be applied, for example, to interactive floorplan editing, and it is especially useful for large layouts, where individual edits would be cumbersome. We demonstrate populating 2D layouts with tens to hundreds of objects by propagating relatively few edit operations. © 2014 ACM 0730-0301/2014/03- ART15 $15.00.

Vocal effort with changing talker-to-listener distance in different acoustic environments

DEFF Research Database (Denmark)

Pelegrin Garcia, David; Smits, Bertrand; Brunskog, Jonas

2011-01-01

Talkers adjust their vocal effort to communicate at different distances, aiming to compensate for the sound propagation losses. The present paper studies the influence of four acoustically different rooms on the speech produced by 13 male talkers addressing a listener at four distances. Talkers...... raised their vocal intensity by between 1.3 and 2.2 dB per double distance to the listener and lowered it as a linear function of the quantity “room gain” at a rate of 3.6 dB/dB. There were also significant variations in the mean fundamental frequency, both across distance (3.8 Hz per double distance......) and among environments (4.3 Hz), and in the long-term standard deviation of the fundamental frequency among rooms (4 Hz). In the most uncomfortable rooms to speak in, talkers prolonged the voiced segments of the speech they produced, either as a side-effect of increased vocal intensity or in order...

Daytime tropical D region parameters from short path VLF phase and amplitude

Science.gov (United States)

Thomson, Neil R.

2010-09-01

Observed phases and amplitudes of VLF radio signals, propagating on a short (˜300-km) path, are used to find improved parameters for the lowest edge of the (D region of the) Earth's ionosphere. The phases, relative to GPS 1-s pulses, and the amplitudes were measured both near (˜100 km from) the transmitter, where the direct ground wave is very dominant, and at distances of ˜300 km near where the ionospherically reflected waves form a (modal) minimum with the (direct) ground wave. The signals came from the 19.8 kHz, 1 MW transmitter, NWC, on the North West Cape of Australia, propagating ˜300 km ENE, mainly over the sea, to the vicinity of Karratha/Dampier on the N.W. coast of Australia. The bottom edge of the mid-day tropical/equatorial ionosphere was thus found to be well-modeled by H‧ = 70.5 ± 0.5 km and β = 0.47 ± 0.03 km-1 where H‧ and β are the traditional height and sharpness parameters as used by Wait and by the U.S. Navy in their Earth-ionosphere VLF radio waveguide programs. U.S. Navy modal waveguide code calculations are also compared with those from the wave hop code of Berry and Herman (1971). At least for the vertical electric fields on the path studied here, the resulting phase and amplitude differences (between the ˜100-km and ˜300-km sites) agree very well after just a small adjustment of ˜0.2 km in H‧ between the two codes. Such short paths also allow more localization than the usual long paths; here this localization is to low latitudes.

Safe Laser Beam Propagation for Interplanetary Links

Science.gov (United States)

Wilson, Keith E.

2011-01-01

Ground-to-space laser uplinks to Earth–orbiting satellites and deep space probes serve both as a beacon and an uplink command channel for deep space probes and Earth-orbiting satellites. An acquisition and tracking point design to support a high bandwidth downlink from a 20-cm optical terminal on an orbiting Mars spacecraft typically calls for 2.5 kW of 1030-nm uplink optical power in 40 micro-radians divergent beams.2 The NOHD (nominal ocular hazard distance) of the 1030nm uplink is in excess of 2E5 km, approximately half the distance to the moon. Recognizing the possible threat of high power laser uplinks to the flying public and to sensitive Earth-orbiting satellites, JPL developed a three-tiered system at its Optical Communications Telescope Laboratory (OCTL) to ensure safe laser beam propagation through navigational and near-Earth space.

Propagation behavior of two transverse surface waves in a three-layer piezoelectric/piezomagnetic structure

Science.gov (United States)

Nie, Guoquan; Liu, Jinxi; Liu, Xianglin

2017-10-01

Propagation of transverse surface waves in a three-layer system consisting of a piezoelectric/piezomagnetic (PE/PM) bi-layer bonded on an elastic half-space is theoretically investigated in this paper. Dispersion relations and mode shapes for transverse surface waves are obtained in closed form under electrically open and shorted boundary conditions at the upper surface. Two transverse surface waves related both to Love-type wave and Bleustein-Gulyaev (B-G) type wave propagating in corresponding three-layer structure are discussed through numerically solving the derived dispersion equation. The results show that Love-type wave possesses the property of multiple modes, it can exist all of the values of wavenumber for every selected thickness ratios regardless of the electrical boundary conditions. The presence of PM interlayer makes the phase velocity of Love-type wave decrease. There exist two modes allowing the propagation of B-G type wave under electrically shorted circuit, while only one mode appears in the case of electrically open circuit. The modes of B-G type wave are combinations of partly normal dispersion and partly anomalous dispersion whether the electrically open or shorted. The existence range of mode for electrically open case is greatly related to the thickness ratios, with the thickness of PM interlayer increasing the wavenumber range for existence of B-G type wave quickly shortened. When the thickness ratio is large enough, the wavenumber range of the second mode for electrically shorted circuit is extremely narrow which can be used to remove as an undesired mode. The propagation behaviors and mode shapes of transverse surface waves can be regulated by the modification of the thickness of PM interlayer. The obtained results provide a theoretical prediction and basis for applications of PE-PM composites and acoustic wave devices.

Measuring propagation delay over a coded serial communication channel using FPGAs

International Nuclear Information System (INIS)

Jansweijer, P.P.M.; Peek, H.Z.

2011-01-01

Measurement and control applications are increasingly using distributed system technologies. In such applications, which may be spread over large distances, it is often necessary to synchronize system timing and know with great precision the time offsets between parts of the system. Measuring the propagation delay over a coded serial communication channel using serializer/deserializer (SerDes) functionality in FPGAs is described. The propagation delay between transmitter and receiver is measured with a resolution of a single unit interval (i.e. a serial link running at 3.125 Gbps provides a 320 ps resolution). The technique has been demonstrated to work over 100 km fibre to verify the feasibility for application in the future KM3NeT telescope.

The impact of SFCL and SMES integration on the distance relay

Energy Technology Data Exchange (ETDEWEB)

Yang, Jun, E-mail: JYang@whu.edu.cn [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Zhang, Liling; Wang, Xinpu; Chen, Lei [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Chen, Yanxia [Beijing Electric Power Research Institute, Beijing 100075 (China)

2016-11-15

Highlights: • The impact of SFCL and SMES integration on the circle distance relay is studied. • The detailed models of SFCL and SMES with distance delay are built in MATLAB. • The integration of SFCL and SMES does influence the operation of distance relay. • An improved distance relay to prevent mal-operation is proposed and verified. - Abstract: The superconducting fault current limiter (SFCL) is an ideal short-circuit fault current limiting device that can limit the fault current without any delay and control the voltage drop of the non-fault line. The superconducting magnetic energy storage (SMES) device can exchange the active and reactive power independently, so it is applied broadly to improve power system stability. With SFCL, the low voltage ride-through capability of SMES can be enhanced as well as its MW and MJ capacities. The distance relay is a key electrical apparatus that will trip circuit breakers to protect electrical devices from short circuit faults. Due to the application of SFCL and SMES integration, the voltage and current in power grid will change accordingly, and the operation characteristic of distance relay may be affected. In this paper, the impact of a bridge-type SFCL and SMES integration on the circle distance relay is studied. And simulation results show that the integration of SFCL and SMES does influence the measured impedance of distance relay, which can lead to mal-operation of the circle distance relay. Furthermore, an improved distance relay is proposed and verified.

The impact of SFCL and SMES integration on the distance relay

International Nuclear Information System (INIS)

Yang, Jun; Zhang, Liling; Wang, Xinpu; Chen, Lei; Chen, Yanxia

2016-01-01

Highlights: • The impact of SFCL and SMES integration on the circle distance relay is studied. • The detailed models of SFCL and SMES with distance delay are built in MATLAB. • The integration of SFCL and SMES does influence the operation of distance relay. • An improved distance relay to prevent mal-operation is proposed and verified. - Abstract: The superconducting fault current limiter (SFCL) is an ideal short-circuit fault current limiting device that can limit the fault current without any delay and control the voltage drop of the non-fault line. The superconducting magnetic energy storage (SMES) device can exchange the active and reactive power independently, so it is applied broadly to improve power system stability. With SFCL, the low voltage ride-through capability of SMES can be enhanced as well as its MW and MJ capacities. The distance relay is a key electrical apparatus that will trip circuit breakers to protect electrical devices from short circuit faults. Due to the application of SFCL and SMES integration, the voltage and current in power grid will change accordingly, and the operation characteristic of distance relay may be affected. In this paper, the impact of a bridge-type SFCL and SMES integration on the circle distance relay is studied. And simulation results show that the integration of SFCL and SMES does influence the measured impedance of distance relay, which can lead to mal-operation of the circle distance relay. Furthermore, an improved distance relay is proposed and verified.

Representing distance, consuming distance

DEFF Research Database (Denmark)

Larsen, Gunvor Riber

Title: Representing Distance, Consuming Distance Abstract: Distance is a condition for corporeal and virtual mobilities, for desired and actual travel, but yet it has received relatively little attention as a theoretical entity in its own right. Understandings of and assumptions about distance...... are being consumed in the contemporary society, in the same way as places, media, cultures and status are being consumed (Urry 1995, Featherstone 2007). An exploration of distance and its representations through contemporary consumption theory could expose what role distance plays in forming...

Propagation of the Lissajous singularity dipole emergent from non-paraxial polychromatic beams

Science.gov (United States)

Haitao, Chen; Gao, Zenghui; Wang, Wanqing

2017-06-01

The propagation of the Lissajous singularity dipole (LSD) emergent from the non-paraxial polychromatic beams is studied. It is found that the handedness reversal of Lissajous singularities, the change in the shape of Lissajous figures, as well as the creation and annihilation of the LSD may take place by varying the propagation distance, off-axis parameter, wavelength, or amplitude factor. Comparing with the LSD emergent from paraxial polychromatic beams, the output field of non-paraxial polychromatic beams is more complicated, which results in some richer dynamic behaviors of Lissajous singularities, such as more Lissajous singularities and no vanishing of a single Lissajous singularity at the plane z>0.

THE IMPACT OF CONTAMINATED RR LYRAE/GLOBULAR CLUSTER PHOTOMETRY ON THE DISTANCE SCALE

Energy Technology Data Exchange (ETDEWEB)

Majaess, D.; Turner, D.; Lane, D. [Department of Astronomy and Physics, Saint Mary' s University, Halifax, NS B3H 3C3 (Canada); Gieren, W., E-mail: dmajaess@ap.smu.ca [Departamento de Astronomia, Universidad de Concepcion, Casilla 160-C, CL Concepcion (Chile)

2012-06-10

RR Lyrae variables and the stellar constituents of globular clusters are employed to establish the cosmic distance scale and age of the universe. However, photometry for RR Lyrae variables in the globular clusters M3, M15, M54, M92, NGC 2419, and NGC 6441 exhibit a dependence on the clustercentric distance. For example, variables and stars positioned near the crowded high-surface brightness cores of the clusters may suffer from photometric contamination, which invariably affects a suite of inferred parameters (e.g., distance, color excess, absolute magnitude, etc.). The impetus for this study is to mitigate the propagation of systematic uncertainties by increasing awareness of the pernicious impact of contaminated and radial-dependent photometry.

Atmospheric Physics and Sound Propagation

Science.gov (United States)

1950-09-01

has 2U flush mounting plates into which may be screwed short support rpds on whi.cn ä platform may .he mounted for suppörtihg a person> or longer...particle trhose rest position ig 4 distance x from the source z(0j,t) s Z cos art I Asa parameter (not Travelsngfeh)- £ (A) -» Z (1-eos wiX ) f»,(A

High Energy Laser Beam Propagation in the Atmosphere: The Integral Invariants of the Nonlinear Parabolic Equation and the Method of Moments

Science.gov (United States)

Manning, Robert M.

2012-01-01

The method of moments is used to define and derive expressions for laser beam deflection and beam radius broadening for high-energy propagation through the Earth s atmosphere. These expressions are augmented with the integral invariants of the corresponding nonlinear parabolic equation that describes the electric field of high-energy laser beam to propagation to yield universal equations for the aforementioned quantities; the beam deflection is a linear function of the propagation distance whereas the beam broadening is a quadratic function of distance. The coefficients of these expressions are then derived from a thin screen approximation solution of the nonlinear parabolic equation to give corresponding analytical expressions for a target located outside the Earth s atmospheric layer. These equations, which are graphically presented for a host of propagation scenarios, as well as the thin screen model, are easily amenable to the phase expansions of the wave front for the specification and design of adaptive optics algorithms to correct for the inherent phase aberrations. This work finds application in, for example, the analysis of beamed energy propulsion for space-based vehicles.

Distance measurement and wave dispersion in a Liouville-string approach to quantum gravity

CERN Document Server

Amelino-Camelia, G; Mavromatos, Nikolaos E; Nanopoulos, Dimitri V

1997-01-01

Within a Liouville approach to non-critical string theory, we discuss space-time foam effects on the propagation of low-energy particles. We find an induced frequency-dependent dispersion in the propagation of a wave packet, and observe that this would affect the outcome of measurements involving low-energy particles as probes. In particular, the maximum possible order of magnitude of the space-time foam effects would give rise to an error in the measurement of distance comparable to that independently obtained in some recent heuristic quantum-gravity analyses. We also briefly compare these error estimates with the precision of astrophysical measurements.

Enhanced propagation for relativistic laser pulses in inhomogeneous plasmas using hollow channels.

Science.gov (United States)

Fuchs, J; d'Humières, E; Sentoku, Y; Antici, P; Atzeni, S; Bandulet, H; Depierreux, S; Labaune, C; Schiavi, A

2010-11-26

The influence of long (several millimeters) and hollow channels, bored in inhomogeneous ionized plasma by using a long pulse laser beam, on the propagation of short, ultraintense laser pulses has been studied. Compared to the case without a channel, propagation in channels significantly improves beam transmission and maintains a beam quality close to propagation in vacuum. In addition, the growth of the forward-Raman instability is strongly reduced. These results are beneficial for the direct scheme of the fast ignitor concept of inertial confinement fusion as we demonstrate, in fast-ignition-relevant conditions, that with such channels laser energy can be carried through increasingly dense plasmas close to the fuel core with minimal losses.

Increased Prevalence of the IL-6-174C Genetic Polymorphism in Long Distance Swimmers.

Science.gov (United States)

Ben-Zaken, Sigal; Meckel, Yoav; Nemet, Dan; Kassem, Eias; Eliakim, Alon

2017-09-01

The IL-6 -174G/C single nucleotide polymorphism (SNP) functionally affects IL-6 activity, with the G-allele associated with increased IL-6 levels. The C-allele was found to be associated with exercise-induced skeletal muscle damage. The aim of the present study was to examine the association between the IL-6 -174G/C polymorphism and athletic performance among elite swimmers and runners. The study sample included 180 track and field athletes and 80 swimmers. Track and field athletes were assigned to three sub-groups: long-distance runners, middle-distance runners and short-distance runners. Swimmers were assigned to two subgroups: long-distance swimmers and short-distance swimmers. The control group consisted of 123 non-athletic healthy individuals. Genomic DNA was extracted from peripheral blood following a standard protocol. Genotyping was performed using polymerase chain reaction (PCR). The CC genotype and C-allele frequency were significantly higher in the long-distance swimmers (18 and 43%, respectively) compared to the long-distance runners (3 and 14%, respectively, p < 0.001); middle-distance runners (4 and 22%, respectively, p < 0.001); and controls (5 and 19%, respectively, p < 0.001). In addition, the CC genotype and C-allele frequency were significantly higher (p < 0.001) in long-distance swimmers compared to short-distance swimmers (18 versus 5% and 43 versus 29% for the CC genotype and C-allele frequency, respectively). The higher frequency of the C-allele and CC genotype among long-distance swimmers suggests that the rarity of exercise-associated rhabdomyolysis among swimmers is probably related to other sports-specific or water-related protective mechanisms. It is possible that swimming selection in talented endurance athletes who are C-allele carriers represents an example of genetically-dependent sports selection.

Increased Prevalence of the IL-6 -174C Genetic Polymorphism in Long Distance Swimmers

Directory of Open Access Journals (Sweden)

Ben-Zaken Sigal

2017-08-01

Full Text Available The IL-6 -174G/C single nucleotide polymorphism (SNP functionally affects IL-6 activity, with the G-allele associated with increased IL-6 levels. The C-allele was found to be associated with exercise-induced skeletal muscle damage. The aim of the present study was to examine the association between the IL-6 -174G/C polymorphism and athletic performance among elite swimmers and runners. The study sample included 180 track and field athletes and 80 swimmers. Track and field athletes were assigned to three sub-groups: long-distance runners, middle-distance runners and short-distance runners. Swimmers were assigned to two subgroups: long-distance swimmers and short-distance swimmers. The control group consisted of 123 non-athletic healthy individuals. Genomic DNA was extracted from peripheral blood following a standard protocol. Genotyping was performed using polymerase chain reaction (PCR. The CC genotype and C-allele frequency were significantly higher in the long-distance swimmers (18 and 43%, respectively compared to the long-distance runners (3 and 14%, respectively, p < 0.001; middle-distance runners (4 and 22%, respectively, p < 0.001; and controls (5 and 19%, respectively, p < 0.001. In addition, the CC genotype and C-allele frequency were significantly higher (p < 0.001 in long-distance swimmers compared to short-distance swimmers (18 versus 5% and 43 versus 29% for the CC genotype and C-allele frequency, respectively. The higher frequency of the C-allele and CC genotype among long-distance swimmers suggests that the rarity of exercise-associated rhabdomyolysis among swimmers is probably related to other sports-specific or water-related protective mechanisms. It is possible that swimming selection in talented endurance athletes who are C-allele carriers represents an example of genetically-dependent sports selection.

In Vitro Propagation Of Nepalese Orchids: A Review

Directory of Open Access Journals (Sweden)

Silva Jaime A. Teixeira da

2014-12-01

Full Text Available Nepalese orchids are made up of 458 taxa. Despite a ban on the collection and trade of all orchid species in Nepal, numerous anthropogenic factors are leading to the rapid loss of natural stands of germplasm. Biotechnology, specifically in vitro propagation, may be the only viable solution for preserving and reintroducing endangered germplasm back into the wild. Despite the large germplasm base, only tissue culture studies have been conducted, and most have focused almost exclusively on in vitro seed germination, the bulk of which have been conducted in the past few years. No other biotechnological advances have yet been made. This brief review provides a short synopsis of the advances made thus far in the in vitro propagation of Nepalese orchids.

Ion pulse propagation through a previously unfilled electrostatic aperture lens accelerating column

International Nuclear Information System (INIS)

Rutkowski, H.L.; Eylon, S.; Keeney, D.S.; Chen, Y.J.; Hewett, D.W.; Barnard, J.

1993-01-01

Heavy Ion Fusion experiments require very high current beams with excellent beam quality during a short pulse. Scaled experiments planned at LBL require very short pulses (μsec) compared to what one expects in an HIF driver (20-30 μs). A 1MV acceleration column composed of aperture lenses has been constructed at LBL in order to study the propagation effects on such ion pulses. The column is initially empty of space charge but with the full acceleration potential applied. A short current pulse is then injected into the column with a planar diode open-quotes current valve.close quotes Effects on the pulse propagation due to rise time, pulse duration, and beam size have been studied. Experiments on transported beam current and emittance have been conducted using a carbon arc plasma source (2 double-prime and .5 double-prime diameter) and a 1 double-prime diameter alumino-silicate potassium ion source. Computer simulations using a 2.5D time dependent code are compared with the experimental data

a case series in habitual distance runners

African Journals Online (AJOL)

muscle injury, aponeurotic tears, ligament injuries, tendinopathy and evaluation of soft tissue ... the point of preventing visualisation of sections of the vessel lumen. (Figure 6). ... 11 constant, then intermittent. Short distances ... Gielen S, Schuler G, Adams V. Cardiovascular effects of exercise training: molecular mechanisms.

Is the Distance Worth It? Patients With Rectal Cancer Traveling to High-Volume Centers Experience Improved Outcomes.

Science.gov (United States)

Xu, Zhaomin; Becerra, Adan Z; Justiniano, Carla F; Boodry, Courtney I; Aquina, Christopher T; Swanger, Alex A; Temple, Larissa K; Fleming, Fergal J

2017-12-01

It is unclear whether traveling long distances to high-volume centers would compensate for travel burden among patients undergoing rectal cancer resection. The purpose of this study was to determine whether operative volume outweighs the advantages of being treated locally by comparing the outcomes of patients with rectal cancer treated at local, low-volume centers versus far, high-volume centers. This was a population-based study. The National Cancer Database was queried for patients with rectal cancer. Patients with stage II or III rectal cancer who underwent surgical resection between 2006 and 2012 were included. The outcomes of interest were margins, lymph node yield, receipt of neoadjuvant chemoradiation, adjuvant chemotherapy, readmission within 30 days, 30-day and 90-day mortality, and 5-year overall survival. A total of 18,605 patients met inclusion criteria; 2067 patients were in the long-distance/high-volume group and 1362 in the short-distance/low-volume group. The median travel distance was 62.6 miles for the long-distance/high-volume group and 2.3 miles for the short-distance/low-volume group. Patients who were younger, white, privately insured, and stage III were more likely to have traveled to a high-volume center. When controlled for patient factors, stage, and hospital factors, patients in the short-distance/low-volume group had lower odds of a lymph node yield ≥12 (OR = 0.51) and neoadjuvant chemoradiation (OR = 0.67) and higher 30-day (OR = 3.38) and 90-day mortality (OR = 2.07) compared with those in the long-distance/high-volume group. The short-distance/low-volume group had a 34% high risk of overall mortality at 5 years compared with the long-distance/high-volume group. We lacked data regarding patient and physician decision making and surgeon-specific factors. Our results indicate that when controlled for patient, tumor, and hospital factors, patients who traveled a long distance to a high-volume center had improved lymph node yield

Short distance line of sight laser communication

International Nuclear Information System (INIS)

Mudassar, A.A.; Hussain, H.; Jamil-ur-Rehman

1998-01-01

Communication methods based on lasers as carrier are well known. In our work we have made a two way laser based communication system for short range (<2 Km) line of sight communication. A small piece of plane mirror (100% reflector) was mounted on the centre of a speaker cone. The speaker was positioned close to the opening of laser such that He-Ne laser beam (10 mW) after reflection from the mirror is directed towards the receiver. There is a pre-amplifier and an amplifier between a microphone and the speaker. When the diagram of the speaker vibrates, it positionally modulates the laser beam. On the receiving end, there is a photo diode, a pre-amplifier, an amplifier and a head phone. So the man on the receiving end can decode the sound signal. On each stage there is a transmitter and a receiver assembled close to each other. So the two way communication is possible in the range 20 to 20 Khz. (author)

Distance Dependent Model for the Delay Power Spectrum of In-room Radio Channels

DEFF Research Database (Denmark)

Steinböck, Gerhard; Pedersen, Troels; Fleury, Bernard Henri

2013-01-01

A model based on experimental observations of the delay power spectrum in closed rooms is proposed. The model includes the distance between the transmitter and the receiver as a parameter which makes it suitable for range based radio localization. The experimental observations motivate the proposed...... model of the delay power spectrum with a primary (early) component and a reverberant component (tail). The primary component is modeled as a Dirac delta function weighted according to an inverse distance power law (d-n). The reverberant component is an exponentially decaying function with onset equal...... to the propagation time between transmitter and receiver. Its power decays exponentially with distance. The proposed model allows for the prediction of e.g. the path loss, mean delay, root mean squared (rms) delay spread, and kurtosis versus the distance. The model predictions are validated by measurements...

The SYOEKSY research project. Electrically-powered vehicles in ring rail line feeder traffic and short-distance travel; Saehkoeiset ajoneuvot kehaeradan syoettoe- ja asiointiliikenteessae. SYOEKSY-tutkimushankkeen loppuraportti 21.9.2011

Energy Technology Data Exchange (ETDEWEB)

2011-07-01

The research report is divided into three sections: a general description of the project, separate reports on each of the themes investigated and a summary of the research results and recommendations. Section 2 deals with themes such as: Low-emissions-technology solutions for traffic and their technical prerequisites in an urban environment and the results obtained from pilot projects. New service models based on electrically-powered traffic technology with an assessment of their feasibility and their effect on urban infrastructure and levels of CO{sub 2} emissions. User needs in new feeder traffic, short-distance travel and other journeys on personal business together with proposals for planning measures which will promote sustainable mobility in new residential areas. The prerequisites for electrically-powered feeder traffic and short-distance travel are therefore handled in a wide-ranging manner. A condensed version of the project conclusions and recommendations is provided in Section 3. A list of the data sources and publications resulting from project work can be found at the end of the report

Fatigue crack propagation under combined cyclic mechanical loading and electric field in piezoelectric ceramics

International Nuclear Information System (INIS)

Shirakihara, Kaori; Tanaka, Keisuke; Akiniwa, Yoshiaki; Suzuki, Yasuyoshi; Mukai, Hirokatsu

2006-01-01

Fatigue crack propagation tests of PZT specimens were performed under cyclic four-point bending with and without superposition of electric fields. The specimens were poled in the longitudinal direction (PL specimens) perpendicular to the crack plane. The crack propagation rate for the case of open circuit was faster than that for the case of short circuit. The application of a negative or positive electric field parallel to the poling direction accelerated the crack propagation rate, and the amount of acceleration was larger for the case of the negative field. The change of the crack propagation rate with crack extension can be divided into three regions. In the region I, the crack propagation rate decreases with increasing crack length, and then turn to increase in the region III. In the region II, the propagation rate is nearly constant. The mechanisms of fatigue crack propagation were correlated to domain switching near the crack tip. The grain boundary fracture was predominant in the low-rate region, while transgranular fracture became abundant on the unstable fracture surface. (author)

Interplay of hot electrons from localized and propagating plasmons.

Science.gov (United States)

Hoang, Chung V; Hayashi, Koki; Ito, Yasuo; Gorai, Naoki; Allison, Giles; Shi, Xu; Sun, Quan; Cheng, Zhenzhou; Ueno, Kosei; Goda, Keisuke; Misawa, Hiroaki

2017-10-03

Plasmon-induced hot-electron generation has recently received considerable interest and has been studied to develop novel applications in optoelectronics, photovoltaics and green chemistry. Such hot electrons are typically generated from either localized plasmons in metal nanoparticles or propagating plasmons in patterned metal nanostructures. Here we simultaneously generate these heterogeneous plasmon-induced hot electrons and exploit their cooperative interplay in a single metal-semiconductor device to demonstrate, as an example, wavelength-controlled polarity-switchable photoconductivity. Specifically, the dual-plasmon device produces a net photocurrent whose polarity is determined by the balance in population and directionality between the hot electrons from localized and propagating plasmons. The current responsivity and polarity-switching wavelength of the device can be varied over the entire visible spectrum by tailoring the hot-electron interplay in various ways. This phenomenon may provide flexibility to manipulate the electrical output from light-matter interaction and offer opportunities for biosensors, long-distance communications, and photoconversion applications.Plasmon-induced hot electrons have potential applications spanning photodetection and photocatalysis. Here, Hoang et al. study the interplay between hot electrons generated by localized and propagating plasmons, and demonstrate wavelength-controlled polarity-switchable photoconductivity.

Multiloop soliton and multibreather solutions of the short pulse model equation

International Nuclear Information System (INIS)

Matsuno, Yoshimasa

2007-01-01

We develop a systematic procedure for constructing the multisoliton solutions of the short pulse (SP) model equation which describes the propagation of ultra-short pulses in nonlinear medica. We first introduce a novel hodograph transformation to convert the SP equation into the sine-Gordon (sG) equation. With the soliton solutions of the sG equation, the system of linear partial differential equations governing the inverse mapping can be integrated analytically to obtain the soliton solutions of the SP equation in the form of the parametric representation. By specifying the soliton parameters, we obtain the multiloop and multibreather solutions. We investigate the asymptotic behavior of both solutions and confirm their solitonic feature. The nonsingular breather solutions may play an important role in studying the propagation of ultra-short pulses in an optical fibre. (author)

Modeling Water Motion near Seismic Waves Propagating across a Graded Seabed, as Generated by Man-Made Impacts

Directory of Open Access Journals (Sweden)

Richard A. Hazelwood

2016-08-01

Full Text Available Seismic interface waves generated by seabed impacts are believed to have biological importance. Various wave types are of interest to seismologists, who can minimize the unwanted, but often dominant, ground roll waves with suitable instrumentation. Waves made by dredging and piling have been measured using geophones and found to be of this interface type, which propagate much more slowly than the pressure waves in the water column above. Short interface wavelets of a few cycles were modeled using transient finite element analysis (FEA. Wavelets with low losses have been modeled using graded sediment data from the literature. They do not radiate energy away from the interface because the evanescent acoustic pressures they generate decay rapidly with distance from the seabed. Associated water particle velocities are much greater than would be expected from similar acoustic pressure measurements in a free field. This motion is significant to aquatic life which is dependent on inertial sensors (otoliths, etc. to respond to the environment. Additional amplification of the horizontal seabed motion of the adjacent water is predicted for a short seismic wavelet modeled in a graded solid seabed. Further recent analysis studied the distribution of the energy flux within the sediment layers.

A Relative-Localization Algorithm Using Incomplete Pairwise Distance Measurements for Underwater Applications

Directory of Open Access Journals (Sweden)

Kae Y. Foo

2010-01-01

Full Text Available The task of localizing underwater assets involves the relative localization of each unit using only pairwise distance measurements, usually obtained from time-of-arrival or time-delay-of-arrival measurements. In the fluctuating underwater environment, a complete set of pair-wise distance measurements can often be difficult to acquire, thus hindering a straightforward closed-form solution in deriving the assets' relative coordinates. An iterative multidimensional scaling approach is presented based upon a weighted-majorization algorithm that tolerates missing or inaccurate distance measurements. Substantial modifications are proposed to optimize the algorithm, while the effects of refractive propagation paths are considered. A parametric study of the algorithm based upon simulation results is shown. An acoustic field-trial was then carried out, presenting field measurements to highlight the practical implementation of this algorithm.

Short fusion

CERN Multimedia

2002-01-01

French and UK researchers are perfecting a particle accelerator technique that could aid the quest for fusion energy or make X-rays that are safer and produce higher-resolution images. Led by Dr Victor Malka from the Ecole Nationale Superieure des Techniques Avancees in Paris, the team has developed a better way of accelerating electrons over short distances (1 page).

Quantum noise and superluminal propagation

International Nuclear Information System (INIS)

Segev, Bilha; Milonni, Peter W.; Babb, James F.; Chiao, Raymond Y.

2000-01-01

Causal ''superluminal'' effects have recently been observed and discussed in various contexts. The question arises whether such effects could be observed with extremely weak pulses, and what would prevent the observation of an ''optical tachyon.'' Aharonov, Reznik, and Stern (ARS) [Phys. Rev. Lett. 81, 2190 (1998)] have argued that quantum noise will preclude the observation of a superluminal group velocity when the pulse consists of one or a few photons. In this paper we reconsider this question both in a general framework and in the specific example, suggested by Chiao, Kozhekin, and Kurizki (CKK) [Phys. Rev. 77, 1254 (1996)], of off-resonant, short-pulse propagation in an optical amplifier. We derive in the case of the amplifier a signal-to-noise ratio that is consistent with the general ARS conclusions when we impose their criteria for distinguishing between superluminal propagation and propagation at the speed c. However, results consistent with the semiclassical arguments of CKK are obtained if weaker criteria are imposed, in which case the signal can exceed the noise without being ''exponentially large.'' We show that the quantum fluctuations of the field considered by ARS are closely related to superfluorescence noise. More generally, we consider the implications of unitarity for superluminal propagation and quantum noise and study, in addition to the complete and truncated wave packets considered by ARS, the residual wave packet formed by their difference. This leads to the conclusion that the noise is mostly luminal and delayed with respect to the superluminal signal. In the limit of a very weak incident signal pulse, the superluminal signal will be dominated by the noise part, and the signal-to-noise ratio will therefore be very small. (c) 2000 The American Physical Society

Focal shift and faculae dimension of focused flat beam propagating in turbulent atmosphere

International Nuclear Information System (INIS)

Zhang Jianzhu; Li Youkuan; Zhang Feizhou; An Jianzhu

2011-01-01

Through theoretic analysis and numerical simulation,the focal shift of a focused flat beam propagating in turbulent atmosphere is studied. When a focused flat beam propagates in turbulent atmosphere, the effect of turbulence will induce the focal spot to move toward the transmitter. The turbulence is stronger and the diameter of transmitter is smaller, the measure of focal shift is larger. When adjusting the focus of transmitter and letting the focal spot of beam locate on detector, the laser intensity received by detector is not the strongest. The laser intensity will be the strongest if the focus of transmitter equals to the distance from transmitter to detector. (authors)

Distance distribution of bystander effects in alpha-particle irradiated cell populations using a CR-39-based culture dish

International Nuclear Information System (INIS)

Gaillard, S.; Pusset, D.; Toledo, S.M. de; Azzam, E.I.; Fromm, M.

2008-01-01

Propagation of induced biological effects from irradiated to non-irradiated cells is known to occur in cell cultures exposed to low fluences of charged particles. These bystander effects are currently investigated using microbeam or non-microbeam (broad beams) irradiation techniques. Identification of the targeted and non-targeted bystander cells is critical to our understanding of mechanisms underlying such effects. We developed a novel cell culture dish where the base consists of a thin CR-39 sheet grafted on a thin polyethylene terephthalate (PET) foil. The validity of this device in identifying not only irradiated cells, but also the cellular compartment traversed by the particle track is described. We have optimized track etch parameters that do not interfere with measurement of induced biological endpoints under normal incident irradiation. Thus the culture dishes can be used to determine distance distributions for the propagation of induced biological effects from a hit cell to bystander cells. We describe the computer code developed to determine the distance distributions of propagated biological stress responses in normal human fibroblast cells exposed to very low fluences of alpha particles

Pulse propagation in tapered wiggler free electron lasers

International Nuclear Information System (INIS)

Goldstein, J.C.; Colson, W.B.

1981-01-01

The one-dimensional theory of short pulse propagation in free electron lasers is extended to tapered wiggler devices and is used to study the behavior of an oscillator with parameter values close to those expected in forthcoming experiments. It is found that stable laser output is possible only over a small range of optical cavity lengths. Optical pulse characteristcs are presented and are found to change considerably over this range

Long-distance transmission of light in a scintillator-based radiation detector

Science.gov (United States)

Dowell, Jonathan L.; Talbott, Dale V.; Hehlen, Markus P.

2017-07-11

Scintillator-based radiation detectors capable of transmitting light indicating the presence of radiation for long distances are disclosed herein. A radiation detector can include a scintillator layer and a light-guide layer. The scintillator layer is configured to produce light upon receiving incident radiation. The light-guide layer is configured to receive light produced by the scintillator layer and either propagate the received light through the radiation detector or absorb the received light and emit light, through fluorescence, that is propagated through the radiation detector. A radiation detector can also include an outer layer partially surrounding the scintillator layer and light-guide layer. The index of refraction of the light-guide layer can be greater than the index of refraction of adjacent layers.

Evaluation of heat transfer tube failure propagation due to sodium-water reaction in steam generator

International Nuclear Information System (INIS)

Nei, Hiromichi

1978-01-01

An evaluation was made of heat transfer tube failure propagation due to sodium-water reaction wastage in a sodium heated steam generator, by comparing an empirically derived wastage equation with leak detector responses. The experimental data agreed well with the wastage equation even for different values of distance-to-nozzle diameter ratio, though the formula had been based on wastage data obtained for only one given distance. The time taken for failure propagation was estimated for a prototype steam generator, and compared with the responses characteristics of acoustic detectors and level gages. It was found that there exists a range of leak rate between 0.5 and 100 g/sec, where the level gage can play a useful role in leak detection. The acoustic detector can be expected to respond more rapidly than the cover gas pressure gage, if noise is kept below ten times the value observed in an experimental facility, SWAT-2. (auth.)

Sleep habits, alertness, cortisol levels, and cardiac autonomic activity in short-distance bus drivers: differences between morning and afternoon shifts.

Science.gov (United States)

Diez, Joaquín J; Vigo, Daniel E; Lloret, Santiago Pérez; Rigters, Stephanie; Role, Noelia; Cardinali, Daniel P; Chada, Daniel Pérez

2011-07-01

To evaluate sleep, alertness, salivary cortisol levels, and autonomic activity in the afternoon and morning shifts of a sample of short-distance bus drivers. A sample of 47 bus drivers was evaluated. Data regarding subjects and working characteristics, alertness (psychomotor vigilance task), sleep habits (Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Actigraphy), endocrine stress response (salivary cortisol), and autonomic activity (heart-rate variability) were collected. Sleep restriction was highly prevalent. Drivers in the morning shift slept 1 hour less than those in the afternoon shift, showed lower reaction time performance, a flattening of cortisol morning-evening difference, and higher overweight prevalence. The differences found between morning and afternoon shifts point out to the need of the implementation of educational strategies to compensate the sleep loss associated with an early work schedule.

Fixation distance and fixation duration to vertical road signs.

Science.gov (United States)

Costa, Marco; Simone, Andrea; Vignali, Valeria; Lantieri, Claudio; Palena, Nicola

2018-05-01

The distance of first-fixation to vertical road signs was assessed in 22 participants while driving a route of 8.34 km. Fixations to road signs were recorded by a mobile eye-movement-tracking device synchronized to GPS and kinematic data. The route included 75 road signs. First-fixation distance and fixation duration distributions were positively skewed. Median distance of first-fixation was 51 m. Median fixation duration was 137 ms with a modal value of 66 ms. First-fixation distance was linearly related to speed and fixation duration. Road signs were gazed at a much closer distance than their visibility distance. In a second study a staircase procedure was used to test the presentation-time threshold that lead to a 75% accuracy in road sign identification. The threshold was 35 ms, showing that short fixations to a road signs could lead to a correct identification. Copyright © 2018 Elsevier Ltd. All rights reserved.

Multi-image acquisition-based distance sensor using agile laser spot beam.

Science.gov (United States)

Riza, Nabeel A; Amin, M Junaid

2014-09-01

We present a novel laser-based distance measurement technique that uses multiple-image-based spatial processing to enable distance measurements. Compared with the first-generation distance sensor using spatial processing, the modified sensor is no longer hindered by the classic Rayleigh axial resolution limit for the propagating laser beam at its minimum beam waist location. The proposed high-resolution distance sensor design uses an electronically controlled variable focus lens (ECVFL) in combination with an optical imaging device, such as a charged-coupled device (CCD), to produce and capture different laser spot size images on a target with these beam spot sizes different from the minimal spot size possible at this target distance. By exploiting the unique relationship of the target located spot sizes with the varying ECVFL focal length for each target distance, the proposed distance sensor can compute the target distance with a distance measurement resolution better than the axial resolution via the Rayleigh resolution criterion. Using a 30 mW 633 nm He-Ne laser coupled with an electromagnetically actuated liquid ECVFL, along with a 20 cm focal length bias lens, and using five spot images captured per target position by a CCD-based Nikon camera, a proof-of-concept proposed distance sensor is successfully implemented in the laboratory over target ranges from 10 to 100 cm with a demonstrated sub-cm axial resolution, which is better than the axial Rayleigh resolution limit at these target distances. Applications for the proposed potentially cost-effective distance sensor are diverse and include industrial inspection and measurement and 3D object shape mapping and imaging.

Revisiting the thermal effect on shock wave propagation in weakly ionized plasmas

International Nuclear Information System (INIS)

Zhou, Qianhong; Dong, Zhiwei; Yang, Wei

2016-01-01

Many researchers have investigated shock propagation in weakly ionized plasmas and observed the following anomalous effects: shock acceleration, shock recovery, shock weakening, shock spreading, and splitting. It was generally accepted that the thermal effect can explain most of the experimental results. However, little attention was paid to the shock recovery. In this paper, the shock wave propagation in weakly ionized plasmas is studied by fluid simulation. It is found that the shock acceleration, weakening, and splitting appear after it enters the plasma (thermal) region. The shock splits into two parts right after it leaves the thermal region. The distance between the splitted shocks keeps decreasing until they recover to one. This paper can explain a whole set of features of the shock wave propagation in weakly ionized plasmas. It is also found that both the shock curvature and the splitting present the same photoacoustic deflection (PAD) signals, so they cannot be distinguished by the PAD experiments.

Hermite-cosine-Gaussian laser beam and its propagation characteristics in turbulent atmosphere.

Science.gov (United States)

Eyyuboğlu, Halil Tanyer

2005-08-01

Hermite-cosine-Gaussian (HcosG) laser beams are studied. The source plane intensity of the HcosG beam is introduced and its dependence on the source parameters is examined. By application of the Fresnel diffraction integral, the average receiver intensity of HcosG beam is formulated for the case of propagation in turbulent atmosphere. The average receiver intensity is seen to reduce appropriately to various special cases. When traveling in turbulence, the HcosG beam initially experiences the merging of neighboring beam lobes, and then a TEM-type cosh-Gaussian beam is formed, temporarily leading to a plain cosh-Gaussian beam. Eventually a pure Gaussian beam results. The numerical evaluation of the normalized beam size along the propagation axis at selected mode indices indicates that relative spreading of higher-order HcosG beam modes is less than that of the lower-order counterparts. Consequently, it is possible at some propagation distances to capture more power by using higher-mode-indexed HcosG beams.

DISTANCES TO DARK CLOUDS: COMPARING EXTINCTION DISTANCES TO MASER PARALLAX DISTANCES

International Nuclear Information System (INIS)

Foster, Jonathan B.; Jackson, James M.; Stead, Joseph J.; Hoare, Melvin G.; Benjamin, Robert A.

2012-01-01

We test two different methods of using near-infrared extinction to estimate distances to dark clouds in the first quadrant of the Galaxy using large near-infrared (Two Micron All Sky Survey and UKIRT Infrared Deep Sky Survey) surveys. Very long baseline interferometry parallax measurements of masers around massive young stars provide the most direct and bias-free measurement of the distance to these dark clouds. We compare the extinction distance estimates to these maser parallax distances. We also compare these distances to kinematic distances, including recent re-calibrations of the Galactic rotation curve. The extinction distance methods agree with the maser parallax distances (within the errors) between 66% and 100% of the time (depending on method and input survey) and between 85% and 100% of the time outside of the crowded Galactic center. Although the sample size is small, extinction distance methods reproduce maser parallax distances better than kinematic distances; furthermore, extinction distance methods do not suffer from the kinematic distance ambiguity. This validation gives us confidence that these extinction methods may be extended to additional dark clouds where maser parallaxes are not available.

Quantum teleportation of propagating quantum microwaves

Energy Technology Data Exchange (ETDEWEB)

Di Candia, R.; Felicetti, S.; Sanz, M. [University of the Basque Country UPV/EHU, Department of Physical Chemistry, Bilbao (Spain); Fedorov, K.G.; Menzel, E.P. [Bayerische Akademie der Wissenschaften, Walther-Meissner-Institut, Garching (Germany); Technische Universitaet Muenchen, Physik-Department, Garching (Germany); Zhong, L.; Deppe, F.; Gross, R. [Bayerische Akademie der Wissenschaften, Walther-Meissner-Institut, Garching (Germany); Technische Universitaet Muenchen, Physik-Department, Garching (Germany); Nanosystems Initiative Munich (NIM), Muenchen (Germany); Marx, A. [Bayerische Akademie der Wissenschaften, Walther-Meissner-Institut, Garching (Germany); Solano, E. [University of the Basque Country UPV/EHU, Department of Physical Chemistry, Bilbao (Spain); Basque Foundation for Science, IKERBASQUE, Bilbao (Spain)

2015-12-15

Propagating quantum microwaves have been proposed and successfully implemented to generate entanglement, thereby establishing a promising platform for the realisation of a quantum communication channel. However, the implementation of quantum teleportation with photons in the microwave regime is still absent. At the same time, recent developments in the field show that this key protocol could be feasible with current technology, which would pave the way to boost the field of microwave quantum communication. Here, we discuss the feasibility of a possible implementation of microwave quantum teleportation in a realistic scenario with losses. Furthermore, we propose how to implement quantum repeaters in the microwave regime without using photodetection, a key prerequisite to achieve long distance entanglement distribution. (orig.)

Quantum teleportation of propagating quantum microwaves

International Nuclear Information System (INIS)

Di Candia, R.; Felicetti, S.; Sanz, M.; Fedorov, K.G.; Menzel, E.P.; Zhong, L.; Deppe, F.; Gross, R.; Marx, A.; Solano, E.

2015-01-01

Propagating quantum microwaves have been proposed and successfully implemented to generate entanglement, thereby establishing a promising platform for the realisation of a quantum communication channel. However, the implementation of quantum teleportation with photons in the microwave regime is still absent. At the same time, recent developments in the field show that this key protocol could be feasible with current technology, which would pave the way to boost the field of microwave quantum communication. Here, we discuss the feasibility of a possible implementation of microwave quantum teleportation in a realistic scenario with losses. Furthermore, we propose how to implement quantum repeaters in the microwave regime without using photodetection, a key prerequisite to achieve long distance entanglement distribution. (orig.)

Long-distance super-resolution imaging assisted by enhanced spatial Fourier transform.

Science.gov (United States)

Tang, Heng-He; Liu, Pu-Kun

2015-09-07

A new gradient-index (GRIN) lens that can realize enhanced spatial Fourier transform (FT) over optically long distances is demonstrated. By using an anisotropic GRIN metamaterial with hyperbolic dispersion, evanescent wave in free space can be transformed into propagating wave in the metamaterial and then focused outside due to negative-refraction. Both the results based on the ray tracing and the finite element simulation show that the spatial frequency bandwidth of the spatial FT can be extended to 2.7k(0) (k(0) is the wave vector in free space). Furthermore, assisted by the enhanced spatial FT, a new long-distance (in the optical far-field region) super-resolution imaging scheme is also proposed and the super resolved capability of λ/5 (λ is the wavelength in free space) is verified. The work may provide technical support for designing new-type high-speed microscopes with long working distances.

Propagation of high-current fast electron beam in a dielectric target

International Nuclear Information System (INIS)

Klimo, O.; Debayle, A.; Tikhonchuk, V.T.

2006-01-01

Complete test of publication follows. A relativistic electron beam with very high current density may be produced during the interaction of a short high intensity laser pulse with a solid target. In Fast Ignition approach to Inertial Confinement Fusion, such beam is supposed to heat a part of the precompressed DT fuel pellet to the conditions of an efficient ignition. For successful implementation of Fast Ignition understanding the propagation and energy deposition of the beam is crucial. A number of processes, mostly associated with the return current, are dissipating the energy of the beam or inhibiting its collimated transport, namely the filamentation. Weibel, two-stream or the recently proposed ionization instability. Ionization instability may develop in a solid dielectric target due to the dependence of the propagation velocity of the beam on the beam density. To study the propagation of high current electron beam in dielectric target, we use a one-dimensional relativistic electrostatic simulation code based on the Particle in Cell method. The code includes ionization processes in dielectric material and collisions of newly generated cold electrons. The current density of the relativistic electron beam used in this work is in the range 3-300 GA/cm 2 , while its length roughly corresponds to the beam, produced by a 40 fs laser pulse. Propagation of the beam in the polyethylene target is studied. The code is complemented by an analytical model, which is applicable og a wider range of beam parameters that are currently beyond our computational possibilities. When the head of the beam enters the plastic target, electric field grows rapidly in consequence of the charge separation and it starts to ionize atoms. In the maximum of the field, which is less than 10% of the atomic field, the density of new free electrons is two orders of magnitude higher than the beam density, which is enough for the current neutralization. Cold electrons are accelerated by the field

Numerical simulations of intense charged particle beam propagation in a dielectric wakefield accelerator

International Nuclear Information System (INIS)

Gai, W.; Kanareykin, A.D.; Kustov, A.L.; Simpson, J.

1995-01-01

The propagation of an intense electron beam through a long dielectric tube is a critical issue for the success of the dielectric wakefield acceleration scheme. Due to the head-tail instability, a high current charged particle beam cannot propagate long distance without external focusing. In this paper we examine the beam handling and control problem in the dielectric wakefield accelerator. We show that for the designed 15.6 GHz and 20 GHz dielectric structures a 150 MeV, 40 endash 100 nC beam can be controlled and propagate up to 5 meters without significant particle losses by using external applied focusing and defocusing channel (FODO) around the dielectric tube. Particle dynamics of the accelerated beam is also studied. Our results show that for typical dielectric acceleration structures, the head-tail instabilities can be conveniently controlled in the same way as the driver beam. copyright 1995 American Institute of Physics

Manipulations of Wavefront Propagation: Useful Methods and Applications for Interferometric Measurements and Scanning

Directory of Open Access Journals (Sweden)

Avi Karsenty

2017-01-01

Full Text Available Phase measurements obtained by high-coherence interferometry are restricted by the 2π ambiguity, to height differences smaller than λ/2. A further restriction in most interferometric systems is for focusing the system on the measured object. We present two methods that overcome these restrictions. In the first method, different segments of a measured wavefront are digitally propagated and focused locally after measurement. The divergent distances, by which the diverse segments of the wavefront are propagated in order to achieve a focused image, provide enough information so as to resolve the 2π ambiguity. The second method employs an interferogram obtained by a spectrum constituting a small number of wavelengths. The magnitude of the interferogram’s modulations is utilized to resolve the 2π ambiguity. Such methods of wavefront propagation enable several applications such as focusing and resolving the 2π ambiguity, as described in the article.

Efficient Underwater RSS Value to Distance Inversion Using the Lambert Function

Directory of Open Access Journals (Sweden)

Majid Hosseini

2014-01-01

Full Text Available There are many applications for using wireless sensor networks (WSN in ocean science; however, identifying the exact location of a sensor by itself (localization is still a challenging problem, where global positioning system (GPS devices are not applicable underwater. Precise distance measurement between two sensors is a tool of localization and received signal strength (RSS, reflecting transmission loss (TL phenomena, is widely used in terrestrial WSNs for that matter. Underwater acoustic sensor networks have not been used (UASN, due to the complexity of the TL function. In this paper, we addressed these problems by expressing underwater TL via the Lambert W function, for accurate distance inversion by the Halley method, and compared this to Newton-Raphson inversion. Mathematical proof, MATLAB simulation, and real device implementation demonstrate the accuracy and efficiency of the proposed equation in distance calculation, with fewer iterations, computation stability for short and long distances, and remarkably short processing time. Then, the sensitivities of Lambert W function and Newton-Raphson inversion to alteration in TL were examined. The simulation results showed that Lambert W function is more stable to errors than Newton-Raphson inversion. Finally, with a likelihood method, it was shown that RSS is a practical tool for distance measurement in UASN.

On the transition of short cracks into long fatigue cracks in reactor pressure vessel steels

Directory of Open Access Journals (Sweden)

Singh Rajwinder

2018-01-01

Full Text Available Short fatigue cracks, having dimension less than 1 mm, propagate at much faster rates (da/dN even at lower stress intensity factor range (da/dN as compared to the threshold stress intensity factor range obtained from long fatigue crack growth studies. These short cracks originate at the sub-grain level and some of them ultimately transit into critical long cracks over time. Therefore, designing the components subjected to fatigue loading merely on the long crack growth data and neglecting the short crack growth behavior can overestimate the component’s life. This aspect of short fatigue cracks become even more critical for materials used for safety critical applications such as reactor pressure vessel (RPV steel in nuclear plants. In this work, the transition behaviour of short fatigue crack gowth into long fatigue crack is studied in SA508 Grade 3 Class I low alloy steel used in RPVs. In-situ characterization of initiation, propagation and transition of short fatigue cracks is performed using fatigue stage for Scanning Electron Microscope (SEM in addition to digital microscopes fitted over a servo-hydraulic fatigue machine and correlated with the microtructural information obtained using electron backscatter diffraction (EBSD. SA508 steel having an upper bainitic microstructure have several microstructural interfaces such as phase and grain boundaries that play a significant role in controlling the short fatigue crack propagation. Specially designed and prepared short fatigue specimens (eletro-polished with varying initial crack lengths of the order of tens of microns are used in this study. The transition of such short initial cracks into long cracks is then tracked to give detailed insight into the role of each phase and phase/grain boundary with an objective of establishing Kitagawa-Takahashi diagram for the given RPV steel. The behavior of the transited long cracks is then compared with the crack propagation behavior obtained using

Field margins, foraging distances and their impacts on nesting pollinator success.

Directory of Open Access Journals (Sweden)

Sean A Rands

Full Text Available The areas of wild land around the edges of agricultural fields are a vital resource for many species. These include insect pollinators, to whom field margins provide both nest sites and important resources (especially when adjacent crops are not in flower. Nesting pollinators travel relatively short distances from the nest to forage: most species of bee are known to travel less than two kilometres away. In order to ensure that these pollinators have sufficient areas of wild land within reach of their nests, agricultural landscapes need to be designed to accommodate the limited travelling distances of nesting pollinators. We used a spatially-explicit modelling approach to consider whether increasing the width of wild strips of land within the agricultural landscape will enhance the amount of wild resources available to a nesting pollinator, and if it would impact differently on pollinators with differing foraging strategies. This was done both by creating field structures with a randomised geography, and by using landscape data based upon the British agricultural landscape. These models demonstrate that enhancing field margins should lead to an increase in the availability of forage to pollinators that nest within the landscape. With the exception of species that only forage within a very short range of their nest (less than 125 m, a given amount of field margin manipulation should enhance the proportion of land available to a pollinator for foraging regardless of the distance over which it normally travels to find food. A fixed amount of field edge manipulation should therefore be equally beneficial for both longer-distance nesting foragers such as honeybees, and short-distance foragers such as solitary bees.

Application of Semi-analytical Satellite Theory orbit propagator to orbit determination for space object catalog maintenance

Science.gov (United States)

Setty, Srinivas J.; Cefola, Paul J.; Montenbruck, Oliver; Fiedler, Hauke

2016-05-01

Catalog maintenance for Space Situational Awareness (SSA) demands an accurate and computationally lean orbit propagation and orbit determination technique to cope with the ever increasing number of observed space objects. As an alternative to established numerical and analytical methods, we investigate the accuracy and computational load of the Draper Semi-analytical Satellite Theory (DSST). The standalone version of the DSST was enhanced with additional perturbation models to improve its recovery of short periodic motion. The accuracy of DSST is, for the first time, compared to a numerical propagator with fidelity force models for a comprehensive grid of low, medium, and high altitude orbits with varying eccentricity and different inclinations. Furthermore, the run-time of both propagators is compared as a function of propagation arc, output step size and gravity field order to assess its performance for a full range of relevant use cases. For use in orbit determination, a robust performance of DSST is demonstrated even in the case of sparse observations, which is most sensitive to mismodeled short periodic perturbations. Overall, DSST is shown to exhibit adequate accuracy at favorable computational speed for the full set of orbits that need to be considered in space surveillance. Along with the inherent benefits of a semi-analytical orbit representation, DSST provides an attractive alternative to the more common numerical orbit propagation techniques.

Detection of tumor-like inclusions embedded within human liver tissue using a short-pulsed near-infrared laser beam: Parallel simulations with radiative transfer equation

International Nuclear Information System (INIS)

Asllanaj, Fatmir; Addoum, Ahmad; Contassot-Vivier, Sylvain

2015-01-01

An efficient solution to detect tumor-like inclusions embedded within a human liver tissue model is presented, using illumination by a short-pulsed laser beam. Light propagation was accurately solved using the time-dependent radiative transfer equation, with multithreaded parallel computing. A modified finite volume method based on unstructured grids and the fourth-order Runge–Kutta approach was employed to solve the equation in the (2-D/3-D) spatial and time domains. The normalization technique applied to the Henyey–Greenstein phase function was adopted to ensure numerical stability for values of the anisotropy factor that were close to unity. The presence of one or two circular/spherical inclusions was analyzed from the time and spatially resolved reflectance on the medium bounding surface. The results allowed a minimal size and a maximum distance for the detection of the inclusion to be highlighted. - Highlights: • We detect tumor-like inclusions embedded within a (2D/3D) human liver tissue model. • The technique is based on a short-pulsed near-infrared laser beam. • We solve the (2D/3D) time-dependent RTE, with multithreaded parallel computing. • The presence of one or two circular/spherical inclusions is analyzed. • The results allows a minimal size and a maximum distance for the detection

A tentative theory of large distance physics

International Nuclear Information System (INIS)

Friedan, Daniel

2003-01-01

A theoretical mechanism is devised to determine the large distance physics of spacetime. It is a two dimensional nonlinear model, the lambda model, set to govern the string world surface in an attempt to remedy the failure of string theory, as it stands. The lambda model is formulated to cancel the infrared divergent effects of handles at short distance on the world surface. The target manifold is the manifold of background spacetimes. The coupling strength is the spacetime coupling constant. The lambda model operates at 2d distance Δ -1 , very much shorter than the 2d distance μ -1 where the world surface is seen. A large characteristic spacetime distance L is given by L 2 ln(Δ/μ). Spacetime fields of wave number up to 1=L are the local coordinates for the manifold of spacetimes. The distribution of fluctuations at 2d distances shorter than Δ -1 gives the a priori measure on the target manifold, the manifold of spacetimes. If this measure concentrates at a macroscopic spacetime, then, nearby, it is a measure on the spacetime fields. The lambda model thereby constructs a spacetime quantum field theory, cutoff at ultraviolet distance L, describing physics at distances larger than L. The lambda model also constructs an effective string theory with infrared cutoff L, describing physics at distances smaller than L. The lambda model evolves outward from zero 2d distance, Δ -1 = 0, building spacetime physics starting from L ∞ and proceeding downward in L. L can be taken smaller than any distance practical for experiments, so the lambda model, if right, gives all actually observable physics. The harmonic surfaces in the manifold of spacetimes are expected to have novel nonperturbative effects at large distances. (author)

Improvement of Ultrasonic Distance Measuring System

Directory of Open Access Journals (Sweden)

Jiang Yu

2018-01-01

Full Text Available This paper mainly introduces a kind of ultrasonic distance measuring system with AT89C51 single chip as the core component. The paper expounds the principle of ultrasonic sensor and ultrasonic ranging, hardware circuit and software program, and the results of experiment and analysis.The hardware circuit based on SCM, the software design adopts the advanced microcontroller programming language.The amplitude of the received signal and the time of ultrasonic propagation are regulated by closed loop control. [1,2]The double closed loop control technology for amplitude and time improves the measuring accuracy of the instrument. The experimental results show that greatly improves the measurement accuracy of the system.

Impulse or propagation? How the tides turned in Business Cycle Theory

NARCIS (Netherlands)

Reijnders, J.P.G.

This paper contains a short history of business cycle theory. It is argued that in the course of time the emphasis shifted from a mainly exogenous to a mainly endogenous explanation of the cycle. After the integration of the two approaches in the so-called impulse and propagation theory, the balance

Demonstration of slow light propagation in an optical fiber under dual pump light with co-propagation and counter-propagation

Science.gov (United States)

Qiu, Wei; Liu, Jianjun; Wang, Yuda; Yang, Yujing; Gao, Yuan; Lv, Pin; Jiang, Qiuli

2018-04-01

In this paper, a general theory of coherent population oscillation effect in an Er3+ -doped fiber under the dual-frequency pumping laser with counter-propagation and co-propagation at room temperature is presented. Using the numerical simulation, in case of dual frequency light waves (1480 nm and 980 nm) with co-propagation and counter-propagation, we analyze the effect of the pump optical power ratio (M) on the group speed of light. The group velocity of light can be varied with the change of M. We research the time delay and fractional delay in an Er3+-doped fiber under the dual-frequency pumping laser with counter-propagation and co-propagation. Compared to the methods of the single pumping, the larger time delay can be got by using the technique of dual-frequency laser pumped fiber with co-propagation and counter-propagation.

Axonal propagation of simple and complex spikes in cerebellar Purkinje neurons.

Science.gov (United States)

Khaliq, Zayd M; Raman, Indira M

2005-01-12

In cerebellar Purkinje neurons, the reliability of propagation of high-frequency simple spikes and spikelets of complex spikes is likely to regulate inhibition of Purkinje target neurons. To test the extent to which a one-to-one correspondence exists between somatic and axonal spikes, we made dual somatic and axonal recordings from Purkinje neurons in mouse cerebellar slices. Somatic action potentials were recorded with a whole-cell pipette, and the corresponding axonal signals were recorded extracellularly with a loose-patch pipette. Propagation of spontaneous and evoked simple spikes was highly reliable. At somatic firing rates of approximately 200 spikes/sec, 375 Hz during somatic hyperpolarizations that silenced spontaneous firing to approximately 150 Hz during spontaneous activity. The probability of propagation of individual spikelets could be described quantitatively as a saturating function of spikelet amplitude, rate of rise, or preceding interspike interval. The results suggest that ion channels of Purkinje axons are adapted to produce extremely short refractory periods and that brief bursts of forward-propagating action potentials generated by complex spikes may contribute transiently to inhibition of postsynaptic neurons.

Propagation characteristics of audible noise generated by single corona source under positive DC voltage

Directory of Open Access Journals (Sweden)

Xuebao Li

2017-10-01

Full Text Available The directivity and lateral profile of corona-generated audible noise (AN from a single corona source are measured through experiments carried out in the semi-anechoic laboratory. The experimental results show that the waveform of corona-generated AN consists of a series of random sound pressure pulses whose pulse amplitudes decrease with the increase of measurement distance. A single corona source can be regarded as a non-directional AN source, and the A-weighted SPL (sound pressure level decreases 6 dB(A as doubling the measurement distance. Then, qualitative explanations for the rationality of treating the single corona source as a point source are given on the basis of the Ingard’s theory for sound generation in corona discharge. Furthermore, we take into consideration of the ground reflection and the air attenuation to reconstruct the propagation features of AN from the single corona source. The calculated results agree with the measurement well, which validates the propagation model. Finally, the influence of the ground reflection on the SPL is presented in the paper.

Lateral propagation of MeV electrons generated by femtosecond laser irradiation

International Nuclear Information System (INIS)

Seely, J. F.; Szabo, C. I.; Audebert, P.; Brambrink, E.; Tabakhoff, E.; Hudson, L. T.

2010-01-01

The propagation of MeV electrons generated by intense (≅10 20 W/cm 2 ) femtosecond laser irradiation, in the lateral direction perpendicular to the incident laser beam, was studied using targets consisting of irradiated metal wires and neighboring spectator wires embedded in electrically conductive (aluminum) or resistive (Teflon) substrates. The K shell spectra in the energy range 40-60 keV from wires of Gd, Dy, Hf, and W were recorded by a transmission crystal spectrometer. The spectra were produced by 1s electron ionization in the irradiated wire and by energetic electron propagation through the substrate material to the spectator wire of a different metal. The electron range and energy were determined from the relative K shell emissions from the irradiated and spectator wires separated by varying substrate lateral distances of up to 1 mm. It was found that electron propagation through Teflon was inhibited, compared to aluminum, implying a relatively weak return current and incomplete space-charge neutralization. The energetic electron propagation in the direction parallel to the electric field of the laser beam was larger than perpendicular to the electric field. Energetic electron production was lower when directly irradiating aluminum or Teflon compared to irradiating the heavy metal wires. These experiments are important for the determination of the energetic electron production mechanism and for understanding lateral electron propagation that can be detrimental to fast-ignition fusion and hard x-ray backlighter radiography.

Development and deployment of innovative distance education modules

Energy Technology Data Exchange (ETDEWEB)

Hsu, Wen-Hsing [Nuclear Science Centre, Texas A and M University, 1095 Nuclear Science RD, College Station, Texas 77843 (United States); Reece, W. Daniel [Nuclear Engineering Department, Texas A and M University, College Station, Texas 77843 (United States)

2010-07-01

The potential of distance education/learning to deliver knowledge to learners outside the classroom is increasing dramatically as the technologies evolve. Through the past seven years at Texas A and M University Nuclear Science Centre, media-rich distance learning modules of lectures has been developed using the cutting edge technology available. Accordingly, the framework of modularised distance education modules has been established as well. Each module, closed caption enabled, consists of short interactive videos with animations and quizzes embedded. Those individual videos can be regrouped to form a new module depending on the contents of the lecture. The framework of this system was explained and the procedures of creating those modules were detailed. Different deployment methodologies of those modules were also discussed. (authors)

Development and deployment of innovative distance education modules

International Nuclear Information System (INIS)

Hsu, Wen-Hsing; Reece, W. Daniel

2010-01-01

The potential of distance education/learning to deliver knowledge to learners outside the classroom is increasing dramatically as the technologies evolve. Through the past seven years at Texas A and M University Nuclear Science Centre, media-rich distance learning modules of lectures has been developed using the cutting edge technology available. Accordingly, the framework of modularised distance education modules has been established as well. Each module, closed caption enabled, consists of short interactive videos with animations and quizzes embedded. Those individual videos can be regrouped to form a new module depending on the contents of the lecture. The framework of this system was explained and the procedures of creating those modules were detailed. Different deployment methodologies of those modules were also discussed. (authors)

Geometry on the parameter space of the belief propagation algorithm on Bayesian networks

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Yodai [National Institute of Informatics, Research Organization of Information and Systems, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430 (Japan); Laboratory for Mathematical Neuroscience, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan)

2006-01-30

This Letter considers a geometrical structure on the parameter space of the belief propagation algorithm on Bayesian networks. The statistical manifold of posterior distributions is introduced, and the expression for the information metric on the manifold is derived. The expression is used to construct a cost function which can be regarded as a measure of the distance in the parameter space.

LOL--Limitations of Online Learning--Are We Selling the Open and Distance Education Message Short?

Science.gov (United States)

Todhunter, Barrie

2013-01-01

The thesis of this paper is that the open and distance education sector is based on a framework of terminology that is typologically inconsistent and which lacks clarity, and open and distance education teaching and learning models are examined to explore these concerns. The findings of this analysis are then used to assist in the articulation of…

Contour Propagation Using Feature-Based Deformable Registration for Lung Cancer

Directory of Open Access Journals (Sweden)

Yuhan Yang

2013-01-01

Full Text Available Accurate target delineation of CT image is a critical step in radiotherapy treatment planning. This paper describes a novel strategy for automatic contour propagation, based on deformable registration, for CT images of lung cancer. The proposed strategy starts with a manual-delineated contour in one slice of a 3D CT image. By means of feature-based deformable registration, the initial contour in other slices of the image can be propagated automatically, and then refined by active contour approach. Three algorithms are employed in the strategy: the Speeded-Up Robust Features (SURF, Thin-Plate Spline (TPS, and an adapted active contour (Snake, used to refine and modify the initial contours. Five pulmonary cancer cases with about 400 slices and 1000 contours have been used to verify the proposed strategy. Experiments demonstrate that the proposed strategy can improve the segmentation performance in the pulmonary CT images. Jaccard similarity (JS mean is about 0.88 and the maximum of Hausdorff distance (HD is about 90%. In addition, delineation time has been considerably reduced. The proposed feature-based deformable registration method in the automatic contour propagation improves the delineation efficiency significantly.

Source estimation for propagation processes on complex networks with an application to delays in public transportation systems

NARCIS (Netherlands)

Manitz, J. (Juliane); Harbering, J. (Jonas); M.E. Schmidt (Marie); T. Kneib (Thomas); A. Schöbel (Anita)

2017-01-01

textabstractThe correct identification of the source of a propagation process is crucial in many research fields. As a specific application, we consider source estimation of delays in public transportation networks. We propose two approaches: an effective distance median and a backtracking method.

Assessment of ventricular excitation propagation velocity using intramyocardial electrograms and electron beam tomography images

International Nuclear Information System (INIS)

Kraft, A.; Schreier, G.; Hutten, H.; Kastner, P.; Rienmueller, R.; Grasser, B; Iberer, F.; Tscheliessnigg, K.H.

1999-01-01

The combination of intramyocardial electrogram (IEGM) recordings and 3D-reconstruction of the heart allows to relate electrophysiological with geometrical parameters of the heart. In 12 Heart transplants the distance of two epimyocardially implanted pacemaker leads d x and the propagation time f x have been correlated. Linear regression analysis revealed significant (p < 0,002) and strong (r = 0,82) correlation. The ventricular excitation propagation velocity (VEPV) within the examined patient group was found to be 0,53 m/s with an offset of 14.25 mm, which is caused by the extent of the electrodes and the region of early capture immediately after stimulation. (author)

Electric field studies: TLE-induced waveforms and ground conductivity impact on electric field propagation

Science.gov (United States)

Farges, Thomas; Garcia, Geraldine; Blanc, Elisabeth

2010-05-01

We review in this paper main results obtained from electric field (from VLF to HF) measurement campaigns realized by CEA in the framework of the Eurosprite program [Neubert et al., 2005, 2008] from 2003 to 2009 in France in different configurations. Two main topics have been studied: sprite or elve induced phenomena (radiation or perturbation) and wave propagation. Using a network of 4 stations, VLF radiations from sprite have been successfully located at 10 km from the sprite parent lightning, in agreement with possible sprite location, generally displaced from the parent lightning. The MF (300 kHz - 3 MHz) source bursts were identified simultaneously with the occurrence of sprites observed with cameras [Farges et al., 2004; Neubert et al., 2008]. These observations are compared to recent broadband measurements, assumed to be due to relativistic electron beam radiation related to sprites [Fullekrug et al., 2009]. Recently, in 2009, with a new instrumentation, an ELF tail has been clearly measured after the lightning waveform, while sprites were observed at about 500 km from our station. This ELF tail is usually observed at distances higher than thousand km and is associated to sprite generation. This opens the capacity to measure the charge moment of the parent-lightning, using such measurement close to the source. Farges et al. [2007] showed that just after a lightning return stroke, a strong transient attenuation is very frequently observed in the MF waves of radio transmissions. They showed that this perturbation is due to heating of the lower ionosphere by the lightning-induced EMP during few milliseconds. These perturbations are then the MF radio signature of the lightning EMP effects on the lower ionosphere, in the same way as elves correspond to their optical signature. The experiment also provided the electric field waveforms directly associated to elves, while lightning were not detected by Météorage. Many of them present a double peak feature. The

Transmission characteristics of Bessel-Gaussian vortex beams propagating along both longitudinal and transverse directions in a subway tunnel

Science.gov (United States)

Wang, Xiaohui; Song, Yingxiong

2018-02-01

By exploiting the non-Kolmogorov model and Rytov approximation theory, a propagation model of Bessel-Gaussian vortex beams (BGVB) propagating in a subway tunnel is derived. Based on the propagation model, a model of orbital angular momentum (OAM) mode probability distribution is established to evaluate the propagation performance when the beam propagates along both longitudinal and transverse directions in the subway tunnel. By numerical simulations and experimental verifications, the influences of the various parameters of BGVB and turbulence on the OAM mode probability distribution are evaluated, and the results of simulations are consistent with the experimental statistics. The results verify that the middle area of turbulence is more beneficial for the vortex beam propagation than the edge; when the BGVB propagates along the longitudinal direction in the subway tunnel, the effects of turbulence on the OAM mode probability distribution can be decreased by selecting a larger anisotropy parameter, smaller coherence length, larger non-Kolmogorov power spectrum coefficient, smaller topological charge number, deeper subway tunnel, lower train speed, and longer wavelength. When the BGVB propagates along the transverse direction, the influences can be also mitigated by adopting a larger topological charge number, less non-Kolmogorov power spectrum coefficient, smaller refractive structure index, shorter wavelength, and shorter propagation distance.

Engineering equations for characterizing non-linear laser intensity propagation in air with loss.

Science.gov (United States)

Karr, Thomas; Stotts, Larry B; Tellez, Jason A; Schmidt, Jason D; Mansell, Justin D

2018-02-19

The propagation of high peak-power laser beams in real atmospheres will be affected at long range by both linear and nonlinear effects contained therein. Arguably, J. H. Marburger is associated with the mathematical characterization of this phenomenon. This paper provides a validated set of engineering equations for characterizing the self-focusing distance from a laser beam propagating through non-turbulent air with, and without, loss as well as three source configurations: (1) no lens, (2) converging lens and (3) diverging lens. The validation was done against wave-optics simulation results. Some validated equations follow Marburger completely, but others do not, requiring modification of the original theory. Our results can provide a guide for numerical simulations and field experiments.

Comparison of propagation-based phase-contrast tomography approaches for the evaluation of dentin microstructure

Science.gov (United States)

Deyhle, Hans; Weitkamp, Timm; Lang, Sabrina; Schulz, Georg; Rack, Alexander; Zanette, Irene; Müller, Bert

2012-10-01

The complex hierarchical structure of human tooth hard tissues, enamel and dentin, guarantees function for decades. On the micrometer level the dentin morphology is dominated by the tubules, micrometer-narrow channels extending from the dentin-enamel junction to the pulp chamber. Their structure has been extensively studied, mainly with two-dimensional approaches. Dentin tubules are formed during tooth growth and their orientation is linked to the morphology of the nanometer-sized components, which is of interest for example for the development of bio-inspired dental fillings. Therefore, a method has to be identified that can access the three-dimensional organization of the tubules, e.g. density and orientation. Tomographic setups with pixel sizes in the sub-micrometer range allow for the three-dimensional visualization of tooth dentin tubules both in phase and absorption contrast modes. We compare high-resolution tomographic scans reconstructed with propagation based phase retrieval algorithms as well as reconstructions without phase retrieval concerning spatial and density resolution as well as rendering of the dentin microstructure to determine the approach best suited for dentin tubule imaging. Reasonable results were obtained with a single-distance phase retrieval algorithm and a propagation distance of about 75% of the critical distance of d2/λ, where d is the size of the smallest objects identifiable in the specimen and λ is the X-ray wavelength.

Propagation dynamics of off-axis symmetrical and asymmetrical vortices embedded in flat-topped beams

Science.gov (United States)

Zhang, Xu; Wang, Haiyan

2017-11-01

In this paper, propagation dynamics of off-axis symmetrical and asymmetrical optical vortices(OVs) embedded in flat-topped beams have been explored numerically based on rigorous scalar diffraction theory. The distribution properties of phase and intensity play an important role in driving the propagation dynamics of OVs. Numerical results show that the single off-axis vortex moves in a straight line. The displacement of the single off-axis vortex becomes smaller, when either the order of flatness N and the beam size ω0are increased or the off-axis displacement d is decreased. In addition, the phase singularities of high order vortex beams can be split after propagating a certain distance. It is also demonstrated that the movement of OVs are closely related with the spatial symmetrical or asymmetrical distribution of vortex singularities field. Multiple symmetrical and asymmetrical optical vortices(OVs) embedded in flat-topped beams can interact and rotate. The investment of the propagation dynamics of OVs may have many applications in optical micro-manipulation and optical tweezers.

Special Course on Interaction of Propagation and Digital Transmission Techniques

Science.gov (United States)

1986-10-01

Longwave Broadcast Systems Many of the fixed/ground based vertical monopole antennas are of the "small antenna" variety characterized by a very small...Don Carlos, L. Mice , M. Deeble, and R. Boebel) who have sponsored propagation research. Also I want to express my appreciation to Boyd Burgess of RAE... monopole versus distance for several types of surfaces like wet and dry ground, sea and fresh water and ice C5D. Fig.2 shows one of these curves for

Time-dependent corrosion fatique crack propagation in 7000 series aluminum alloys. M.S. Thesis

Science.gov (United States)

Mason, Mark E.

1995-01-01

The goal of this research is to characterize environmentally assisted subcritical crack growth for the susceptible short-longitudinal orientation of aluminum alloy 7075-T651, immersed in acidified and inhibited NaCl solution. This work is necessary in order to provide a basis for incorporating environmental effects into fatigue crack propagation life prediction codes such as NASA-FLAGRO (NASGRO). This effort concentrates on determining relevant inputs to a superposition model in order to more accurately model environmental fatigue crack propagation.

Front Propagation in Stochastic Neural Fields

KAUST Repository

Bressloff, Paul C.

2012-01-01

We analyze the effects of extrinsic multiplicative noise on front propagation in a scalar neural field with excitatory connections. Using a separation of time scales, we represent the fluctuating front in terms of a diffusive-like displacement (wandering) of the front from its uniformly translating position at long time scales, and fluctuations in the front profile around its instantaneous position at short time scales. One major result of our analysis is a comparison between freely propagating fronts and fronts locked to an externally moving stimulus. We show that the latter are much more robust to noise, since the stochastic wandering of the mean front profile is described by an Ornstein-Uhlenbeck process rather than a Wiener process, so that the variance in front position saturates in the long time limit rather than increasing linearly with time. Finally, we consider a stochastic neural field that supports a pulled front in the deterministic limit, and show that the wandering of such a front is now subdiffusive. © 2012 Society for Industrial and Applied Mathematics.

Distance Magic-Type and Distance Antimagic-Type Labelings of Graphs

Science.gov (United States)

Freyberg, Bryan J.

Generally speaking, a distance magic-type labeling of a graph G of order n is a bijection l from the vertex set of the graph to the first n natural numbers or to the elements of a group of order n, with the property that the weight of each vertex is the same. The weight of a vertex x is defined as the sum (or appropriate group operation) of all the labels of vertices adjacent to x. If instead we require that all weights differ, then we refer to the labeling as a distance antimagic-type labeling. This idea can be generalized for directed graphs; the weight will take into consideration the direction of the arcs. In this manuscript, we provide new results for d-handicap labeling, a distance antimagic-type labeling, and introduce a new distance magic-type labeling called orientable Gamma-distance magic labeling. A d-handicap distance antimagic labeling (or just d-handicap labeling for short) of a graph G = ( V,E) of order n is a bijection l from V to the set {1,2,...,n} with induced weight function [special characters omitted]. such that l(xi) = i and the sequence of weights w(x 1),w(x2),...,w (xn) forms an arithmetic sequence with constant difference d at least 1. If a graph G admits a d-handicap labeling, we say G is a d-handicap graph. A d-handicap incomplete tournament, H(n,k,d ) is an incomplete tournament of n teams ranked with the first n natural numbers such that each team plays exactly k games and the strength of schedule of the ith ranked team is d more than the i + 1st ranked team. That is, strength of schedule increases arithmetically with strength of team. Constructing an H(n,k,d) is equivalent to finding a d-handicap labeling of a k-regular graph of order n.. In Chapter 2 we provide general constructions for every d for large classes of both n and k, providing breadfth and depth to the catalog of known H(n,k,d)'s. In Chapters 3 - 6, we introduce a new type of labeling called orientable Gamma-distance magic labeling. Let Gamma be an abelian group of order

Short-distance expansion for the electromagnetic half-space Green's tensor: general results and an application to radiative lifetime computations

International Nuclear Information System (INIS)

Panasyuk, George Y; Schotland, John C; Markel, Vadim A

2009-01-01

We obtain a short-distance expansion for the half-space, frequency domain electromagnetic Green's tensor. The small parameter of the theory is ωε 1 L/c, where ω is the frequency, ε 1 is the permittivity of the upper half-space, in which both the source and the point of observation are located, and which is assumed to be transparent, c is the speed of light in vacuum and L is a characteristic length, defined as the distance from the point of observation to the reflected (with respect to the planar interface) position of the source. In the case when the lower half-space (the substrate) is characterized by a complex permittivity ε 2 , we compute the expansion to third order. For the case when the substrate is a transparent dielectric, we compute the imaginary part of the Green's tensor to seventh order. The analytical calculations are verified numerically. The practical utility of the obtained expansion is demonstrated by computing the radiative lifetime of two electromagnetically interacting molecules in the vicinity of a transparent dielectric substrate. The computation is performed in the strong interaction regime when the quasi-particle pole approximation is inapplicable. In this regime, the integral representation for the half-space Green's tensor is difficult to use while its electrostatic limiting expression is grossly inadequate. However, the analytical expansion derived in this paper can be used directly and efficiently. The results of this study are also relevant to nano-optics and near-field imaging, especially when tomographic image reconstruction is involved

Stress wave propagation in linear viscoelasticity

International Nuclear Information System (INIS)

Asada, Kazuo; Fukuoka, Hidekazu.

1992-01-01

Decreasing characteristics of both stress and stress gradient with propagation distance at a 2-dimensional linear viscoelasticity wavefront are derived by using our 3-dimensional theoretical equation for particle velocity discontinuities. By finite-element method code DYNA3D, stress at a noncurvature dilatation wavefront of linear viscoelasticity is shown to decrease exponentially. This result is in good accordance with our theory. By dynamic photoelasticity experiment, stress gradients of urethane rubber plates at 3 types of wavefronts are shown to decrease exponentially at a noncurvature wavefront and are shown to be a decreasing function of (1/√R) exp (α 1 2 /(2α 0 3 ξ)) at a curvature wavefront. These experiment results are in good accordance with our theory. (author)

Distance measurement using frequency scanning interferometry with mode-hoped laser

Science.gov (United States)

Medhat, M.; Sobee, M.; Hussein, H. M.; Terra, O.

2016-06-01

In this paper, frequency scanning interferometry is implemented to measure distances up to 5 m absolutely. The setup consists of a Michelson interferometer, an external cavity tunable diode laser, and an ultra-low expansion (ULE) Fabry-Pérot (FP) cavity to measure the frequency scanning range. The distance is measured by acquiring simultaneously the interference fringes from, the Michelson and the FP interferometers, while scanning the laser frequency. An online fringe processing technique is developed to calculate the distance from the fringe ratio while removing the parts result from the laser mode-hops without significantly affecting the measurement accuracy. This fringe processing method enables accurate distance measurements up to 5 m with measurements repeatability ±3.9×10-6 L. An accurate translation stage is used to find the FP cavity free-spectral-range and therefore allow accurate measurement. Finally, the setup is applied for the short distance calibration of a laser distance meter (LDM).

Development of an imaging-planning program for screen/film and computed radiography mammography for breasts with short chest wall to nipple distance.

Science.gov (United States)

Dong, S L; Su, J L; Yeh, Y H; Chu, T C; Lin, Y C; Chuang, K S

2011-04-01

Imaging breasts with a short chest wall to nipple distance (CWND) using a traditional mammographic X-ray unit is a technical challenge for mammographers. The purpose of this study is the development of an imaging-planning program to assist in determination of imaging parameters of screen/film (SF) and computed radiography (CR) mammography for short CWND breasts. A traditional mammographic X-ray unit (Mammomat 3000, Siemens, Munich, Germany) was employed. The imaging-planning program was developed by combining the compressed breast thickness correction, the equivalent polymethylmethacrylate thickness assessment for breasts and the tube loading (mAs) measurement. Both phantom exposures and a total of 597 exposures were used for examining the imaging-planning program. Results of the phantom study show that the tube loading rapidly decreased with the CWND when the automatic exposure control (AEC) detector was not fully covered by the phantom. For patient exposures with the AEC fully covered by breast tissue, the average fractional tube loadings, defined as the ratio of the predicted mAs using the imaging-planning program and mAs of the mammogram, were 1.10 and 1.07 for SF and CR mammograms, respectively. The predicted mAs values were comparable to the mAs values, as determined by the AEC. By applying the imaging-planning program in clinical practice, the experiential dependence of the mammographer for determination of the imaging parameters for short CWND breasts is minimised.

Distance relay performance in future converter dominated power systems

OpenAIRE

Sarkar, Moumita; Jia, Jundi; Yang, Guangya

2017-01-01

Increasing penetration of converter-based generations in power system has led to new system challenges. Short circuit power response from converter-based generations is different from that of traditional synchronous generators. Power electronic converters can be designed for over-current only up to 1.1-1.25 times of its nominal value. Low availability of short circuit power can cause many challenges such as misoperation of distance relays. The aim of this paper is to investigate the effect of...

Propagation of optical vortex beams and nucleation of vortex-antivortex pairs in disordered nonlinear photonic lattices

International Nuclear Information System (INIS)

Cho, Yeong-Kwon; Kim, Ki-Hong

2014-01-01

The propagation of optical vortex beams through disordered nonlinear photonic lattices is numerically studied. The vortex beams are generated by using a superposition of several Gaussian laser beams arranged in a radially-symmetric manner. The paraxial nonlinear Schroedinger equation describing the longitudinal propagation of the beam array through nonlinear triangular photonic lattices with two-dimensional disorder is solved numerically by using the split-step Fourier method. We find that due to the spatial disorder, the vortex beam is destabilized after propagating a finite distance and new vortex-antivortex pairs are nucleated at the positions of perfect destructive interference. We also find that in the presence of a self-focusing nonlinearity, the vortex-antivortex pair nucleation is suppressed and the vortex beam becomes more stable, while a self-defocusing nonlinearity enhances the vortex-antivortex pair nucleation.

MANGO PROPAGATION

OpenAIRE

ALBERTO CARLOS DE QUEIROZ PINTO; VICTOR GALÁN SAÚCO; SISIR KUMAR MITRA; FRANCISCO RICARDO FERREIRA

2018-01-01

ABSTRACT This Chapter has the objectives to search, through the review of the available literature, important informations on the evolution of mango propagation regarding theoretical and practical aspects from cellular base of sexual propagation, nursery structures and organizations, substrate compositions and uses, importance of rootstock and scion selections, also it will be described the preparation and transport of the grafts (stem and bud) as well as the main asexual propagation methods...

Impact of travel distance to the treatment facility on overall mortality in US patients with prostate cancer.

Science.gov (United States)

Vetterlein, Malte W; Löppenberg, Björn; Karabon, Patrick; Dalela, Deepansh; Jindal, Tarun; Sood, Akshay; Chun, Felix K-H; Trinh, Quoc-Dien; Menon, Mani; Abdollah, Firas

2017-09-01

The objective of this study was to investigate the impact of travel distance to the treating facility on the risk of overall mortality (OM) among US patients with prostate cancer (PCa). In total, 775,999 patients who had PCa in all stages and received treatment with different strategies (radical prostatectomy, radiation therapy, observation, androgen-deprivation therapy, multimodal treatment, and chemotherapy) were drawn from the National Cancer Data Base from 2004 through 2012. Independent predictors of travel distance (intermediate [12.5-49.9 miles] and long [49.9-249.9 miles] vs short[traveled short, intermediate, and long distances, respectively. Residency in rural areas and the receipt of treatment at academic/high-volume centers independently predicted long travel distance. Non-Hispanic black men and Medicaid-insured men were less likely to travel long distances (all P traveling a long distance (hazard ratio, 0.87; 95% confidence interval, 0.83-0.92; P traveling a short distance. This held true among non-Hispanic white men; privately insured and Medicare-insured men; those who underwent radical prostatectomy, received radiation therapy, and received multimodal strategies; and those who received treatment at academic/high-volume centers (P travel distance was associated with an increased OM in Medicaid-insured patients (P traveled long distances for PCa treatment, which is likely to be a reflection of centralization of care and more favorable patient-level characteristics in those travelers. Furthermore, the survival benefit mediated by long travel distances appears to be influenced by baseline socioeconomic, treatment, and facility-level factors. Cancer 2017;123:3241-52. © 2017 American Cancer Society. © 2017 American Cancer Society.

Fluid-driven fracture propagation in heterogeneous media: Probability distributions of fracture trajectories.

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Santillán, David; Mosquera, Juan-Carlos; Cueto-Felgueroso, Luis

2017-11-01

Hydraulic fracture trajectories in rocks and other materials are highly affected by spatial heterogeneity in their mechanical properties. Understanding the complexity and structure of fluid-driven fractures and their deviation from the predictions of homogenized theories is a practical problem in engineering and geoscience. We conduct a Monte Carlo simulation study to characterize the influence of heterogeneous mechanical properties on the trajectories of hydraulic fractures propagating in elastic media. We generate a large number of random fields of mechanical properties and simulate pressure-driven fracture propagation using a phase-field model. We model the mechanical response of the material as that of an elastic isotropic material with heterogeneous Young modulus and Griffith energy release rate, assuming that fractures propagate in the toughness-dominated regime. Our study shows that the variance and the spatial covariance of the mechanical properties are controlling factors in the tortuousness of the fracture paths. We characterize the deviation of fracture paths from the homogenous case statistically, and conclude that the maximum deviation grows linearly with the distance from the injection point. Additionally, fracture path deviations seem to be normally distributed, suggesting that fracture propagation in the toughness-dominated regime may be described as a random walk.

Propagation Characteristics in an Underground Shopping Area for 5GHz-band Wireless Access Systems

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Itokawa, Kiyohiko; Kita, Naoki; Sato, Akio; Matsue, Hideaki; Mori, Daisuke; Watanabe, Hironobu

5-GHz band wireless access systems, such as the RLAN (Radio Local Area Network) system of IEEE802.11a, HiperLAN/2, HiSWANa and AWA, are developed and provide transmission rates over 20 Mbps for indoor use. Those 5-GHz access systems are expected to extend service areas from the office to the so-called “hot-spot" in public areas. Underground shopping malls are one of the anticipated service areas for such a nomadic wireless access service. Broadband propagation characteristics are required for radio zone design in an underground mall environment despite previous results obtained by narrow band measurements. This paper presents results of an experimental study on the propagation characteristics for broadband wireless access systems in an underground mall environment. First, broadband propagation path loss is measured and formulated considering human body shadowing. A ray trace simulation is used to clarify the basic propagation mechanism in such a closed environment. Next, a distance dependency of the delay spread during a crowded time period, rush hour, is found to be at most 65 nsec, which is under the permitted maximum value of the present 5-GHz systems. Finally, above propagation characteristics support the result of transmission test carried out by using AWA equipment.

Scaling analysis of the non-Abelian quasiparticle tunneling in [Formula: see text] FQH states.

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Li, Qi; Jiang, Na; Wan, Xin; Hu, Zi-Xiang

2018-06-27

Quasiparticle tunneling between two counter propagating edges through point contacts could provide information on its statistics. Previous study of the short distance tunneling displays a scaling behavior, especially in the conformal limit with zero tunneling distance. The scaling exponents for the non-Abelian quasiparticle tunneling exhibit some non-trivial behaviors. In this work, we revisit the quasiparticle tunneling amplitudes and their scaling behavior in a full range of the tunneling distance by putting the electrons on the surface of a cylinder. The edge-edge distance can be smoothly tuned by varying the aspect ratio for a finite size cylinder. We analyze the scaling behavior of the quasiparticles for the Read-Rezayi [Formula: see text] states for [Formula: see text] and 4 both in the short and long tunneling distance region. The finite size scaling analysis automatically gives us a critical length scale where the anomalous correction appears. We demonstrate this length scale is related to the size of the quasiparticle at which the backscattering between two counter propagating edges starts to be significant.

Simulation of light propagation in the thin-film waveguide lens

Science.gov (United States)

Malykh, M. D.; Divakov, D. V.; Sevastianov, L. A.; Sevastianov, A. L.

2018-04-01

In this paper we investigate the solution of the problem of modeling the propagation of electromagnetic radiation in three-dimensional integrated optical structures, such as waveguide lenses. When propagating through three-dimensional waveguide structures the waveguide modes can be hybridized, so the mathematical model of their propagation must take into account the connection of TE- and TM-mode components. Therefore, an adequate consideration of hybridization of the waveguide modes is possible only in vector formulation of the problem. An example of three-dimensional structure that hybridizes waveguide modes is the Luneburg waveguide lens, which also has focusing properties. If the waveguide lens has a radius of the order of several tens of wavelengths, its variable thickness at distances of the order of several wavelengths is almost constant. Assuming in this case that the electromagnetic field also varies slowly in the direction perpendicular to the direction of propagation, one can introduce a small parameter characterizing this slow varying and decompose the solution in powers of the small parameter. In this approach, in the zeroth approximation, scalar diffraction problems are obtained, the solution of which is less resource-consuming than the solution of vector problems. The calculated first-order corrections of smallness describe the connection of TE- and TM-modes, so the solutions obtained are weakly-hybridized modes. The formulation of problems and methods for their numerical solution in this paper are based on the authors' research on waveguide diffraction on a lens in a scalar formulation.

IBEX - annular beam propagation experiment

International Nuclear Information System (INIS)

Mazarakis, M.G.; Miller, R.B.; Shope, S.L.; Poukey, J.W.; Ramirez, J.J.; Ekdahl, C.A.; Adler, R.J.

1983-01-01

IBEX is a 4-MV, 100-kA, 20-ns cylindrical isolated Blumlein accelerator. In the experiments reported here, the accelerator is fitted with a specially designed foilless diode which is completely immersed in a uniform magnetic field. Several diode geometries have been studied as a function of magnetic field strength. The beam propagates a distance of 50 cm (approx. 10 cyclotron wavelengths) in vacuum before either striking a beam stop or being extracted through a thin foil. The extracted beam was successfully transported 60 cm downstream into a drift pipe filled either with 80 or 640 torr air. The main objectives of this experiment were to establish the proper parameters for the most quiescent 4 MV, 20 to 40 kA annular beam, and to compare the results with available theory and numerical code simulations

Short time propagation of a singular wave function: Some surprising results

Science.gov (United States)

Marchewka, A.; Granot, E.; Schuss, Z.

2007-08-01

The Schrödinger evolution of an initially singular wave function was investigated. First it was shown that a wide range of physical problems can be described by initially singular wave function. Then it was demonstrated that outside the support of the initial wave function the time evolution is governed to leading order by the values of the wave function and its derivatives at the singular points. Short-time universality appears where it depends only on a single parameter—the value at the singular point (not even on its derivatives). It was also demonstrated that the short-time evolution in the presence of an absorptive potential is different than in the presence of a nonabsorptive one. Therefore, this dynamics can be harnessed to the determination whether a potential is absorptive or not simply by measuring only the transmitted particles density.

The theory of critical distances applied to problems in fracture and fatigue of bone

Directory of Open Access Journals (Sweden)

Emma Brazel

2009-10-01

Full Text Available The theory of critical distances (TCD has been applied to predict notch-based fracture and fatigue in a wide range of materials and components. The present paper describes a series of projects in which we applied this approach to human bone. Using experimental data from the literature, combined with finite element analysis, we showed that the TCD was able to predict the effect of notches and holes on the strength of bone failing in brittle fracture due to monotonic loading, in different loading regimes. Bone also displays short crack effects, leading to R-curve data for both fracture toughness and fatigue crack propagation thresholds; we showed that the TCD could predict this data. This analysis raised a number of questions for discussion, such as the significance of the L value itself in this and other materials. Finally, we applied the TCD to a practical problem in orthopaedic surgery: the management of bone defects, showing that predictions could be made which would enable surgeons to decide on whether a bone graft material would be needed to repair a defect, and to specify what mechanical properties this material should have.

Study on the effect of beam propagation through atmospheric turbulence on standoff nanosecond laser induced breakdown spectroscopy measurements.

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Laserna, J J; Reyes, R Fernández; González, R; Tobaria, L; Lucena, P

2009-06-08

We report on an experimental study of the effect of atmospheric turbulence on laser induced breakdown spectroscopy (LIBS) measurements. The characteristics of the atmosphere dictate specific performance constraints to this technology. Unlike classical laboratory LIBS systems where the distance to the sample is well known and characterized, LIBS systems working at several tens of meters to the target have specific atmospheric propagation conditions that cause the quality of the LIBS signals to be affected to a significant extent. Using a new LIBS based sensor system fitted with a nanosecond laser emitting at 1064 nm, propagation effects at distances of up to 120 m were investigated. The effects observed include wander and scintillation in the outgoing laser beam and in the return atomic emission signal. Plasmas were formed on aluminium targets. Average signal levels and signal fluctuations are measured so the effect of atmospheric turbulence on LIBS measurements is quantified.

Analysis of the Performance of a PAM/PPM/OOK System Operating with OCDMA, under Nonlinear Optical Effects in Optical Fiber Propagation

Science.gov (United States)

Correia, D. G.; Sales, J. C.; Pinto, P. V. F.; Moura, L. P.; Ferreira, A. C.; Menezes, J. W. M.; Guimarães, G. F.; Sombra, A. S. B.

2016-06-01

In this article, we present a numerical simulation study of encoding, decoding and propagation performance of short optical pulses and words with modulations OOK, PAM and PPM in OCDMA systems (Optical Code Division Multiple Access). The encoding and decoding of short pulses are obtained through fiber Bragg grating(FBG - FBG optical) devices, where the codes are inserted through discrete jumps in the optical phase (±π) where Gold codes were used. A figure of merit (SNR - Signal to Noise Ratio) was obtained to quantify the interference in propagation of short optical pulses. An increase in the temporal width was observed. For decoded pulses due to the nonlinearity effect, we observed an increase of 1.3 ps considering the propagation with γ=3 W-1 km-1 and γ=24 W-1 km-1. Analysis of coding and decoding words "a" and "w" was done. Considering the propagation (with γ=9 W-1 km-1) of a word "w", an error occurred in all modulations except for simultaneous PPM/PAM modulation, which is associated to the better autocorrelation characteristics obtained with the OOK, PAM and PPM modulations alone, and could double the transmission rate. The nonlinear effects directly affect the process of the autocorrelation codes due to interference from adjacent chip components of the code.

The influence of creep properties on crack propagation in thermal barrier coatings

International Nuclear Information System (INIS)

Baeker, Martin

2010-01-01

Thermal barrier coatings are used to protect turbine blades from the high temperature of the process gas inside a turbine. They consist of a metallic bond coat and of a ceramic top coat with low thermal conductivity. During service, an additional oxide layer forms between bond coat and top coat that eventually causes failure. Finite element simulations show that the roughness of the interface between top and bond coat is crucial for determining the stress state. Lifetime models have been inferred that assume that cracks form in the peak positions at small oxide thickness and propagate when the oxide layer grows and the stress field shifts. A two-dimensional finite element model of crack propagation in the TBC layer is presented. Since the cracks propagate near a material interface and since plasticity may occur in the bond coat, standard tools of fracture mechanics for predicting the crack propagation direction are difficult to apply. This problem is circumvented in a very simple way by propagating short 'test cracks' in different directions and optimising to find the crack direction with the maximum energy release rate. It is shown that the energy release rate and the crack propagation direction are sensitive to the details of the stress state and especially to the creep properties of the materials. Implications for failure models are discussed.

On-Demand Cell Internal Short Circuit Device

Science.gov (United States)

Darcy, Eric; Keyser, Matthew

2014-01-01

A device implantable in Li-ion cells that can generate a hard internal short circuit on-demand by exposing the cell to 60?C has been demonstrated to be valuable for expanding our understanding of cell responses. The device provides a negligible impact to cell performance and enables the instigation of the 4 general categories of cell internal shorts to determine relative severity and cell design susceptibility. Tests with a 18650 cell design indicates that the anode active material short to the aluminum cathode current collector tends to be more catastrophic than the 3 other types of internal shorts. Advanced safety features (such as shutdown separators) to prevent or mitigate the severity of cell internal shorts can be verified with this device. The hard short success rate achieved to date in 18650 cells is about 80%, which is sufficient for using these cells in battery assemblies for field-failure-relevant, cell-cell thermal runaway propagation verification tests

Quantum-limited heat conduction over macroscopic distances

Science.gov (United States)

Partanen, Matti; Tan, Kuan Yen; Govenius, Joonas; Lake, Russell E.; Mäkelä, Miika K.; Tanttu, Tuomo; Möttönen, Mikko

2016-05-01

The emerging quantum technological apparatuses, such as the quantum computer, call for extreme performance in thermal engineering. Cold distant heat sinks are needed for the quantized electric degrees of freedom owing to the increasing packaging density and heat dissipation. Importantly, quantum mechanics sets a fundamental upper limit for the flow of information and heat, which is quantified by the quantum of thermal conductance. However, the short distance between the heat-exchanging bodies in the previous experiments hinders their applicability in quantum technology. Here, we present experimental observations of quantum-limited heat conduction over macroscopic distances extending to a metre. We achieved this improvement of four orders of magnitude in the distance by utilizing microwave photons travelling in superconducting transmission lines. Thus, it seems that quantum-limited heat conduction has no fundamental distance cutoff. This work establishes the integration of normal-metal components into the framework of circuit quantum electrodynamics, which provides a basis for the superconducting quantum computer. Especially, our results facilitate remote cooling of nanoelectronic devices using faraway in situ-tunable heat sinks. Furthermore, quantum-limited heat conduction is important in contemporary thermodynamics. Here, the long distance may lead to ultimately efficient mesoscopic heat engines with promising practical applications.

A study of infrasound propagation based on high-order finite difference solutions of the Navier-Stokes equations.

Science.gov (United States)

Marsden, O; Bogey, C; Bailly, C

2014-03-01

The feasibility of using numerical simulation of fluid dynamics equations for the detailed description of long-range infrasound propagation in the atmosphere is investigated. The two dimensional (2D) Navier Stokes equations are solved via high fidelity spatial finite differences and Runge-Kutta time integration, coupled with a shock-capturing filter procedure allowing large amplitudes to be studied. The accuracy of acoustic prediction over long distances with this approach is first assessed in the linear regime thanks to two test cases featuring an acoustic source placed above a reflective ground in a homogeneous and weakly inhomogeneous medium, solved for a range of grid resolutions. An atmospheric model which can account for realistic features affecting acoustic propagation is then described. A 2D study of the effect of source amplitude on signals recorded at ground level at varying distances from the source is carried out. Modifications both in terms of waveforms and arrival times are described.

Review of complex networks application in hydroclimatic extremes with an implementation to characterize spatio-temporal drought propagation in continental USA

Science.gov (United States)

Konapala, Goutam; Mishra, Ashok

2017-12-01

The quantification of spatio-temporal hydroclimatic extreme events is a key variable in water resources planning, disaster mitigation, and preparing climate resilient society. However, quantification of these extreme events has always been a great challenge, which is further compounded by climate variability and change. Recently complex network theory was applied in earth science community to investigate spatial connections among hydrologic fluxes (e.g., rainfall and streamflow) in water cycle. However, there are limited applications of complex network theory for investigating hydroclimatic extreme events. This article attempts to provide an overview of complex networks and extreme events, event synchronization method, construction of networks, their statistical significance and the associated network evaluation metrics. For illustration purpose, we apply the complex network approach to study the spatio-temporal evolution of droughts in Continental USA (CONUS). A different drought threshold leads to a new drought event as well as different socio-economic implications. Therefore, it would be interesting to explore the role of thresholds on spatio-temporal evolution of drought through network analysis. In this study, long term (1900-2016) Palmer drought severity index (PDSI) was selected for spatio-temporal drought analysis using three network-based metrics (i.e., strength, direction and distance). The results indicate that the drought events propagate differently at different thresholds associated with initiation of drought events. The direction metrics indicated that onset of mild drought events usually propagate in a more spatially clustered and uniform approach compared to onsets of moderate droughts. The distance metric shows that the drought events propagate for longer distance in western part compared to eastern part of CONUS. We believe that the network-aided metrics utilized in this study can be an important tool in advancing our knowledge on drought

Perception of Egocentric Distance during Gravitational Changes in Parabolic Flight.

Directory of Open Access Journals (Sweden)

Gilles Clément

Full Text Available We explored the effect of gravity on the perceived representation of the absolute distance of objects to the observers within the range from 1.5-6 m. Experiments were performed on board the CNES Airbus Zero-G during parabolic flights eliciting repeated exposures to short periods of microgravity (0 g, hypergravity (1.8 g, and normal gravity (1 g. Two methods for obtaining estimates of perceived egocentric distance were used: verbal reports and visually directed motion toward a memorized visual target. For the latter method, because normal walking is not possible in 0 g, blindfolded subjects translated toward the visual target by pulling on a rope with their arms. The results showed that distance estimates using both verbal reports and blind pulling were significantly different between normal gravity, microgravity, and hypergravity. Compared to the 1 g measurements, the estimates of perceived distance using blind pulling were shorter for all distances in 1.8 g, whereas in 0 g they were longer for distances up to 4 m and shorter for distances beyond. These findings suggest that gravity plays a role in both the sensorimotor system and the perceptual/cognitive system for estimating egocentric distance.

Excitation of Accelerating Plasma Waves by Counter-propagating Laser Beams

International Nuclear Information System (INIS)

Gennady Shvets; Nathaniel J. Fisch; Alexander Pukhov

2001-01-01

Generation of accelerating plasma waves using two counter-propagating laser beams is considered. Colliding-beam accelerator requires two laser pulses: the long pump and the short timing beam. We emphasize the similarities and differences between the conventional laser wakefield accelerator and the colliding-beam accelerator (CBA). The highly nonlinear nature of the wake excitation is explained using both nonlinear optics and plasma physics concepts. Two regimes of CBA are considered: (i) the short-pulse regime, where the timing beam is shorter than the plasma period, and (ii) the parametric excitation regime, where the timing beam is longer than the plasma period. Possible future experiments are also outlined

Nonlocal Peridynamic Modeling and Simulation on Crack Propagation in Concrete Structures

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Dan Huang

2015-01-01

Full Text Available An extended peridynamic approach for crack propagation analysis in concrete structures was proposed. In the peridynamic constitutive model, concrete material was described as a series of interacting particles, and the short-range repulsive force and anisotropic behavior of concrete were taken into account in the expression of the interactive bonding force, which was given in terms of classical elastic constants and peridynamic horizon. The damage of material was defined locally at the level of pairwise bond, and the critical stretch of material bond was described as a function of fracture strength in the classical concrete failure theory. The efficiency and accuracy of the proposed model and algorithms were validated by simulating the propagation of mode I and I-II mixed mode cracks in concrete slabs. Furthermore, crack propagation in a double-edge notched concrete beam subjected to four-point load was simulated, in which the experimental observations are captured naturally as a consequence of the solution.

New long-distance transmissions in Russia may use hvdc

Energy Technology Data Exchange (ETDEWEB)

1940-09-01

Hvdc is considered for Kuibyshev-Moscow and other future Russian long-distance transmissions as a means to obtain higher transmission capacity and lower losses. A total saving of 46% is calculated as compared with ac transmission. An experimental transmission line will be built shortly.

Streak camera measurements of laser pulse temporal dispersion in short graded-index optical fibers

International Nuclear Information System (INIS)

Lerche, R.A.; Phillips, G.E.

1981-01-01

Streak camera measurements were used to determine temporal dispersion in short (5 to 30 meter) graded-index optical fibers. Results show that 50-ps, 1.06-μm and 0.53-μm laser pulses can be propagated without significant dispersion when care is taken to prevent propagation of energy in fiber cladding modes

Propagation of flexural waves in inhomogeneous plates exhibiting hysteretic nonlinearity: Nonlinear acoustic black holes.

Science.gov (United States)

Gusev, Vitalyi E; Ni, Chenyin; Lomonosov, Alexey; Shen, Zhonghua

2015-08-01

Theory accounting for the influence of hysteretic nonlinearity of micro-inhomogeneous material on flexural wave in the plates of continuously varying thickness is developed. For the wedges with thickness increasing as a power law of distance from its edge strong modifications of the wave dynamics with propagation distance are predicted. It is found that nonlinear absorption progressively disappearing with diminishing wave amplitude leads to complete attenuation of acoustic waves in most of the wedges exhibiting black hole phenomenon. It is also demonstrated that black holes exist beyond the geometrical acoustic approximation. Applications include nondestructive evaluation of micro-inhomogeneous materials and vibrations damping. Copyright © 2015 Elsevier B.V. All rights reserved.

Distance associated with marriage migration in a northern and a southern region of Bangladesh: an empirical study.

Science.gov (United States)

Rahman, Md Mizanur; Akter, Shamima; Rahman, Ataur

2010-09-01

This paper investigates the distribution of distance associated with marriage migration in the northern region of Rajshahi and the southern region of Khulna in Bangladesh. The study was conducted in 2007 on 2250 respondents who had migrated due to marriage. Of the wide variety of curves that fitted the distance-marriage/contact data, three are discussed: Pareto, exponential, and Pareto-exponential. Logistic regression models were used to identify the covariates of marriage distance migration. In general, the three functions work better for marriages, whereas Pareto-exponential functions are a superior fit for migrations and marriage distance. The models disclose that the distribution of distance is significantly associated with marriage migration (pPareto-exponential model was 100% stable and its shrinkage was 0.000000125. The main covariates associated with short-distance marriage migration were respondent's education, father's education and religion, whereas age at the time of marriage did not play a significant role in marriage migration. The risk of short-distance migration was greater in higher- than lower-educated Muslim families.

Scattered P'P' waves observed at short distances

Science.gov (United States)

Earle, Paul S.; Rost, Sebastian; Shearer, Peter M.; Thomas, Christine

2011-01-01

We detect previously unreported 1 Hz scattered waves at epicentral distances between 30° and 50° and at times between 2300 and 2450 s after the earthquake origin. These waves likely result from off-azimuth scattering of PKPbc to PKPbc in the upper mantle and crust and provide a new tool for mapping variations in fine-scale (10 km) mantle heterogeneity. Array beams from the Large Aperture Seismic Array (LASA) clearly image the scattered energy gradually emerging from the noise and reaching its peak amplitude about 80 s later, and returning to the noise level after 150 s. Stacks of transverse versus radial slowness (ρt, ρr) show two peaks at about (2, -2) and (-2,-2) s/°, indicating the waves arrive along the major arc path (180° to 360°) and significantly off azimuth. We propose a mantle and surface PKPbc to PKPbc scattering mechanism for these observations because (1) it agrees with the initiation time and distinctive slowness signature of the scattered waves and (2) it follows a scattering path analogous to previously observed deep-mantle PK•KP scattering (Chang and Cleary, 1981). The observed upper-mantle scattered waves and PK•KP waves fit into a broader set of scattered waves that we call P′•d•P′, which can scatter from any depth, d, in the mantle.

Error statistics during the propagation of short optical pulses in a high-speed fibreoptic communication line

International Nuclear Information System (INIS)

Shapiro, E G

2008-01-01

Simple analytic expressions are derived to approximate the bit error rate for data transmission through fibreoptic communication lines. The propagation of optical pulses is directly numerically simulated. Analytic estimates are in good agreement with numerical calculations. (fibreoptic communication)

An automatic contour propagation method to follow parotid gland deformation during head-and-neck cancer tomotherapy

International Nuclear Information System (INIS)

Faggiano, E; Scalco, E; Rizzo, G; Fiorino, C; Broggi, S; Cattaneo, M; Maggiulli, E; Calandrino, R; Dell'Oca, I; Di Muzio, N

2011-01-01

We developed an efficient technique to auto-propagate parotid gland contours from planning kVCT to daily MVCT images of head-and-neck cancer patients treated with helical tomotherapy. The method deformed a 3D surface mesh constructed from manual kVCT contours by B-spline free-form deformation to generate optimal and smooth contours. Deformation was calculated by elastic image registration between kVCT and MVCT images. Data from ten head-and-neck cancer patients were considered and manual contours by three observers were included in both kVCT and MVCT images. A preliminary inter-observer variability analysis demonstrated the importance of contour propagation in tomotherapy application: a high variability was reported in MVCT parotid volume estimation (p = 0.0176, ANOVA test) and a larger uncertainty of MVCT contouring compared with kVCT was demonstrated by DICE and volume variability indices (Wilcoxon signed rank test, p -4 for both indices). The performance analysis of our method showed no significant differences between automatic and manual contours in terms of volumes (p > 0.05, in a multiple comparison Tukey test), center-of-mass distances (p = 0.3043, ANOVA test), DICE values (p = 0.1672, Wilcoxon signed rank test) and average and maximum symmetric distances (p = 0.2043, p = 0.8228 Wilcoxon signed rank tests). Results suggested that our contour propagation method could successfully substitute human contouring on MVCT images.

An automatic contour propagation method to follow parotid gland deformation during head-and-neck cancer tomotherapy

Energy Technology Data Exchange (ETDEWEB)

Faggiano, E; Scalco, E; Rizzo, G [Istituto di Bioimmagini e Fisiologia Molecolare (IBFM), CNR, Milan (Italy); Fiorino, C; Broggi, S; Cattaneo, M; Maggiulli, E; Calandrino, R [Department of Medical Physics, San Raffaele Scientific Institute, Milan (Italy); Dell' Oca, I; Di Muzio, N, E-mail: fiorino.claudio@hsr.it [Department of Radiotherapy, San Raffaele Scientific Institute, Milan (Italy)

2011-02-07

We developed an efficient technique to auto-propagate parotid gland contours from planning kVCT to daily MVCT images of head-and-neck cancer patients treated with helical tomotherapy. The method deformed a 3D surface mesh constructed from manual kVCT contours by B-spline free-form deformation to generate optimal and smooth contours. Deformation was calculated by elastic image registration between kVCT and MVCT images. Data from ten head-and-neck cancer patients were considered and manual contours by three observers were included in both kVCT and MVCT images. A preliminary inter-observer variability analysis demonstrated the importance of contour propagation in tomotherapy application: a high variability was reported in MVCT parotid volume estimation (p = 0.0176, ANOVA test) and a larger uncertainty of MVCT contouring compared with kVCT was demonstrated by DICE and volume variability indices (Wilcoxon signed rank test, p < 10{sup -4} for both indices). The performance analysis of our method showed no significant differences between automatic and manual contours in terms of volumes (p > 0.05, in a multiple comparison Tukey test), center-of-mass distances (p = 0.3043, ANOVA test), DICE values (p = 0.1672, Wilcoxon signed rank test) and average and maximum symmetric distances (p = 0.2043, p = 0.8228 Wilcoxon signed rank tests). Results suggested that our contour propagation method could successfully substitute human contouring on MVCT images.

Measurements of the propagation speed of 511 KeV {gamma}-rays in air and other material media

Energy Technology Data Exchange (ETDEWEB)

Cavalcante, Jose T.P.D.; Silva, Paulo R.J.; Saitovitch, Henrique [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mails: thadeu@cbpf.br; prjs@cbpf.br; henrique@cbpf.br

2007-07-01

The propagation speeds of the 511 KeV {gamma}-rays were measured in several material media, based in a fast-slow coincidence method. The time-resolution of the instrumental system used to perform the experiments allows to get reliable results in covered distances of {approx} 40 cm. (author)

Bistability, multistability and non-reciprocal light propagation in Thue-Morse multilayered structures

International Nuclear Information System (INIS)

Grigoriev, Victor; Biancalana, Fabio

2010-01-01

The nonlinear properties of quasi-periodic photonic crystals based on the Thue-Morse sequence are investigated. The intrinsic spatial asymmetry of these one-dimensional structures for odd generation numbers results in bistability thresholds, which are sensitive to the propagation direction. Along with resonances of perfect transmission, this feature allows us to achieve strongly non-reciprocal propagation and to create an all-optical diode. The salient qualitative features of such optical diode action are readily explained through a simple coupled resonator model. The efficiency of a passive scheme that does not necessitate an additional short pump signal is compared to an active scheme where such a signal is required.

Forecasts of geomagnetic activities and HF radio propagation conditions made at Hiraiso/Japan

Science.gov (United States)

Marubashi, K.; Miyamoto, Y.; Kidokoro, T.; Ishii, T.

1979-01-01

The Hiraiso Branch of RRL prediction techniques are summarized separately for the 27 day recurrent storm and the flare-associated storm. The storm predictions are compared with the actual geomagnetic activities in two ways. The first one is the comparison on a day to day basis. In the second comparison, the accuracy of the storm predictions during 1965-1976 are evaluated. In addition to the storm prediction, short-term predictions of HF radio propagation conditions are conducted at Hiraiso. The HF propagation predictions are briefly described as an example of the applications of the magnetic storm prediction.

Gender and distance influence performance predictors in young swimmers

Directory of Open Access Journals (Sweden)

Paulo Victor Mezzaroba

2013-12-01

Full Text Available Predictors of performance in adult swimmers are constantly changing during youth especially because the training routine begins even before puberty in the modality. Therefore this study aimed to determine the group of parameters that best predict short and middle swimming distance performances of young swimmers of both genders. Thirty-three 10-to 16-years-old male and female competitive swimmers participated in the study. Multiple linear regression (MLR was used considering mean speed of maximum 100, 200 and 400 m efforts as dependent variables, and five parameters groups as possible predictors (anthropometry, body composition, physiological and biomechanical parameters, chronological age/pubic hair. The main results revealed explanatory powers of almost 100% for both genders and all performances, but with different predictors entered in MLR models of each parameter group or all variables. Thus, there are considerable differences in short and middle swimming distance, and males and females predictors that should be considered in training programs.

Short initial length quench on CICC of ITER TF coils

Energy Technology Data Exchange (ETDEWEB)

Nicollet, S.; Ciazynski, D.; Duchateau, J.-L.; Lacroix, B. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Bessette, D.; Rodriguez-Mateos, F. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Coatanea-Gouachet, M. [ELC Engineering, 350 chemin du Verladet, F-13290 Les Milles (France); Gauthier, F. [Soditech Ingenierie, 4 bis allée des Gabians, ZI La Frayère, 06150 Cannes (France)

2014-01-29

Previous quench studies performed for the International Thermonuclear Experimental Reactor (ITER) Toroidal Field (TF) Coils have led to identify two extreme families of quench: first 'severe' quenches over long initial lengths in high magnetic field, and second smooth quenches over short initial lengths in low field region. Detailed analyses and results on smooth quench propagation and detectability on one TF Cable In Conduit Conductor (CICC) with a lower propagation velocity are presented here. The influence of the initial quench energy is shown and results of computations with either a Fast Discharge (FD) of the magnet or without (failure of the voltage quench detection system) are reported. The influence of the central spiral of the conductor on the propagation velocity is also detailed. In the cases of a regularly triggered FD, the hot spot temperature criterion of 150 K (with helium and jacket) is fulfilled for an initial quench length of 1 m, whereas this criterion is exceed (Tmax ≈ 200 K) for an extremely short length of 5 cm. These analyses were carried out using both the Supermagnet(trade mark, serif) and Venecia codes and the comparisons of the results are also discussed.

Short initial length quench on CICC of ITER TF coils

International Nuclear Information System (INIS)

Nicollet, S.; Ciazynski, D.; Duchateau, J.-L.; Lacroix, B.; Bessette, D.; Rodriguez-Mateos, F.; Coatanea-Gouachet, M.; Gauthier, F.

2014-01-01

Previous quench studies performed for the International Thermonuclear Experimental Reactor (ITER) Toroidal Field (TF) Coils have led to identify two extreme families of quench: first 'severe' quenches over long initial lengths in high magnetic field, and second smooth quenches over short initial lengths in low field region. Detailed analyses and results on smooth quench propagation and detectability on one TF Cable In Conduit Conductor (CICC) with a lower propagation velocity are presented here. The influence of the initial quench energy is shown and results of computations with either a Fast Discharge (FD) of the magnet or without (failure of the voltage quench detection system) are reported. The influence of the central spiral of the conductor on the propagation velocity is also detailed. In the cases of a regularly triggered FD, the hot spot temperature criterion of 150 K (with helium and jacket) is fulfilled for an initial quench length of 1 m, whereas this criterion is exceed (Tmax ≈ 200 K) for an extremely short length of 5 cm. These analyses were carried out using both the Supermagnet(trade mark, serif) and Venecia codes and the comparisons of the results are also discussed

Diffusion-controlled interface kinetics-inclusive system-theoretic propagation models for molecular communication systems

Science.gov (United States)

Chude-Okonkwo, Uche A. K.; Malekian, Reza; Maharaj, B. T.

2015-12-01

Inspired by biological systems, molecular communication has been proposed as a new communication paradigm that uses biochemical signals to transfer information from one nano device to another over a short distance. The biochemical nature of the information transfer process implies that for molecular communication purposes, the development of molecular channel models should take into consideration diffusion phenomenon as well as the physical/biochemical kinetic possibilities of the process. The physical and biochemical kinetics arise at the interfaces between the diffusion channel and the transmitter/receiver units. These interfaces are herein termed molecular antennas. In this paper, we present the deterministic propagation model of the molecular communication between an immobilized nanotransmitter and nanoreceiver, where the emission and reception kinetics are taken into consideration. Specifically, we derived closed-form system-theoretic models and expressions for configurations that represent different communication systems based on the type of molecular antennas used. The antennas considered are the nanopores at the transmitter and the surface receptor proteins/enzymes at the receiver. The developed models are simulated to show the influence of parameters such as the receiver radius, surface receptor protein/enzyme concentration, and various reaction rate constants. Results show that the effective receiver surface area and the rate constants are important to the system's output performance. Assuming high rate of catalysis, the analysis of the frequency behavior of the developed propagation channels in the form of transfer functions shows significant difference introduce by the inclusion of the molecular antennas into the diffusion-only model. It is also shown that for t > > 0 and with the information molecules' concentration greater than the Michaelis-Menten kinetic constant of the systems, the inclusion of surface receptors proteins and enzymes in the models

Properties of solar proton events at large heliocentric distances near ecliptic

International Nuclear Information System (INIS)

Khiber, B.; Struminskij, A.B.

2005-01-01

The absolute intensities, fluences and propagation times of the solar protons with the energy of 38-125 MeV, obtained on the basis of the observation data of the Kilskij electron telescope (KET ULYSSES) onboard the ULYSSES cosmic apparatus and GOES proton detector, are compared. The observation data on the solar cosmic rays at the heliocentric distances above 5 a.e. are analyzed for the first time. Certain characteristics of the proton events under consideration and their possible parent flares are presented [ru

Functional magnetic resonance microscopy of long- and short-distance water transport in trees

NARCIS (Netherlands)

Homan, N.

2009-01-01

Due to their long life span, changing climatic conditions are of particular importance for trees. Climate changes will affect the water balance, which can become an important limiting factor for photosynthesis and growth. Long-distance water transport in trees is directly related to the

Horses for courses: a DNA-based test for race distance aptitude in thoroughbred racehorses.

Science.gov (United States)

Hill, Emmeline W; Ryan, Donal P; MacHugh, David E

2012-12-01

Variation at the myostatin (MSTN) gene locus has been shown to influence racing phenotypes in Thoroughbred horses, and in particular, early skeletal muscle development and the aptitude for racing at short distances. Specifically, a single nucleotide polymorphism (SNP) in the first intron of MSTN (g.66493737C/T) is highly predictive of best race distance among Flat racing Thoroughbreds: homozygous C/C horses are best suited to short distance races, heterozygous C/T horses are best suited to middle distance races, and homozygous T/T horses are best suited to longer distance races. Patent applications for this gene marker association, and other linked markers, have been filed. The information contained within the patent applications is exclusively licensed to the commercial biotechnology company Equinome Ltd, which provides a DNA-based test to the international Thoroughbred horse racing and breeding industry. The application of this information in the industry enables informed decision making in breeding and racing and can be used to assist selection to accelerate the rate of change of genetic types among distinct populations (Case Study 1) and within individual breeding operations (Case Study 2).

Pulse propagation in free-electron lasers with a tapered undulator

International Nuclear Information System (INIS)

Goldstein, J.C.; Colson, W.B.

1981-01-01

The one-dimensional theory of short pulse propagation in free electron lasers is extended to tapered undulator devices and is used to study the behavior of an oscillator with parameter values close to those expected in forthcoming experiments. It is found that stable laser output is possible only over a small range of optical cavity lengths. Optical pulse characteristics are presented and are found to change considerably over this range

Climate and the complexity of migratory phenology: sexes, migratory distance, and arrival distributions

Science.gov (United States)

Macmynowski, Dena P.; Root, Terry L.

2007-05-01

The intra- and inter-season complexity of bird migration has received limited attention in climatic change research. Our phenological analysis of 22 species collected in Chicago, USA, (1979 2002) evaluates the relationship between multi-scalar climate variables and differences (1) in arrival timing between sexes, (2) in arrival distributions among species, and (3) between spring and fall migration. The early migratory period for earliest arriving species (i.e., short-distance migrants) and earliest arriving individuals of a species (i.e., males) most frequently correlate with climate variables. Compared to long-distance migrant species, four times as many short-distance migrants correlate with spring temperature, while 8 of 11 (73%) of long-distance migrant species’ arrival is correlated with the North Atlantic Oscillation (NAO). While migratory phenology has been correlated with NAO in Europe, we believe that this is the first documentation of a significant association in North America. Geographically proximate conditions apparently influence migratory timing for short-distance migrants while continental-scale climate (e.g., NAO) seemingly influences the phenology of Neotropical migrants. The preponderance of climate correlations is with the early migratory period, not the median of arrival, suggesting that early spring conditions constrain the onset or rate of migration for some species. The seasonal arrival distribution provides considerable information about migratory passage beyond what is apparent from statistical analyses of phenology. A relationship between climate and fall phenology is not detected at this location. Analysis of the within-season complexity of migration, including multiple metrics of arrival, is essential to detect species’ responses to changing climate as well as evaluate the underlying biological mechanisms.

Front propagation in flipping processes

International Nuclear Information System (INIS)

Antal, T; Ben-Avraham, D; Ben-Naim, E; Krapivsky, P L

2008-01-01

We study a directed flipping process that underlies the performance of the random edge simplex algorithm. In this stochastic process, which takes place on a one-dimensional lattice whose sites may be either occupied or vacant, occupied sites become vacant at a constant rate and simultaneously cause all sites to the right to change their state. This random process exhibits rich phenomenology. First, there is a front, defined by the position of the leftmost occupied site, that propagates at a nontrivial velocity. Second, the front involves a depletion zone with an excess of vacant sites. The total excess Δ k increases logarithmically, Δ k ≅ ln k, with the distance k from the front. Third, the front exhibits ageing-young fronts are vigorous but old fronts are sluggish. We investigate these phenomena using a quasi-static approximation, direct solutions of small systems and numerical simulations

MANGO PROPAGATION

Directory of Open Access Journals (Sweden)

ALBERTO CARLOS DE QUEIROZ PINTO

2018-03-01

Full Text Available ABSTRACT This Chapter has the objectives to search, through the review of the available literature, important informations on the evolution of mango propagation regarding theoretical and practical aspects from cellular base of sexual propagation, nursery structures and organizations, substrate compositions and uses, importance of rootstock and scion selections, also it will be described the preparation and transport of the grafts (stem and bud as well as the main asexual propagation methods their uses and practices. Finally, pattern and quality of graft mangos and their commercialization aspects will be discussed in this Chapter.

Mechanical Energy Propagation and Backscattering in Nominally Dry Soil: Imaging Buried Land Mines

Science.gov (United States)

Sen, Surajit

2003-04-01

The imaging of shallow buried objects in a complex medium, e.g., nominally dry sand, is an outstanding challenge. Such imaging is of relevance in connection with the detection and subsequent imaging of buried non-metallic anti-personnel land mines and in other applications. It has been shown that gentle mechanical impulses and low frequency sound waves with frequencies roughly between 150-350 Hz or so can penetrate distances of up to a foot in sand. Hence, such signals can potentially be useful in the detection and perhaps in the imaging of shallow buried objects. It is presently unclear whether high frequency signals can be effectively used to image shallow buried objects. Impulses can typically penetrate larger distances into sand and soil. Both impulses and continuous sound waves can be used for imaging shallow buried objects. The talk shall briefly review the state-of-the-art in low frequency sound propagation in soil and shall discuss the current understanding of impulse propagation and backscattering in nominally dry sand beds. It will be argued that impulse based imaging may have the potential to be a simple and fast way to detect and image small non-metallic mines. Research supported by the National Science Foundation Grant No. NSF-CMS 0070055.

Dependency distance minimization in understanding of ambiguous structure. Comment on "Dependency distance: A new perspective on syntactic patterns in natural languages" by Haitao Liu et al.

Science.gov (United States)

Zhao, Yiyi

2017-07-01

Dependency Distance, proposed by Hudson [1], calculated by Liu [2,3], is an important concept in Dependency Theory. It can be used as a measure of the syntactic difficulty, and lots of research [2,4] have testified the universal of Dependency Distance in various languages. Human languages seem to present a preference for short dependency distance, which may be explained in terms of general cognitive constraint of limited working memory [5]. Psychological experiments in English, German, Russian and Chinese support the hypothesis that Dependency Distance minimization (DDM) make languages to evolve into some syntactic patterns to reduce memory burden [6-9]. The study of psychology focuses on the process and mechanism of syntactic structure selection in speech comprehension. In many speech comprehension experiments [10], ambiguous structure is an important experimental material.

Dependency distance: A new perspective on syntactic patterns in natural languages

Science.gov (United States)

Liu, Haitao; Xu, Chunshan; Liang, Junying

2017-07-01

Dependency distance, measured by the linear distance between two syntactically related words in a sentence, is generally held as an important index of memory burden and an indicator of syntactic difficulty. Since this constraint of memory is common for all human beings, there may well be a universal preference for dependency distance minimization (DDM) for the sake of reducing memory burden. This human-driven language universal is supported by big data analyses of various corpora that consistently report shorter overall dependency distance in natural languages than in artificial random languages and long-tailed distributions featuring a majority of short dependencies and a minority of long ones. Human languages, as complex systems, seem to have evolved to come up with diverse syntactic patterns under the universal pressure for dependency distance minimization. However, there always exist a small number of long-distance dependencies in natural languages, which may reflect some other biological or functional constraints. Language system may adapt itself to these sporadic long-distance dependencies. It is these universal constraints that have shaped such a rich diversity of syntactic patterns in human languages.

Certain features of FELs with short bunches

International Nuclear Information System (INIS)

Lebedev, A.N.

2006-01-01

The report is devoted to physics of free electron lasers operating in the short-wave domain where the bunch length could be less than the undulator length in the proper frame. Then the current component of the signal is locked within the bunch as in a cavity, while the electromagnetic component propagates freely. In contrast with gyrotrons where this regime can be of interest only for wavelengths comparable with the bunch length, we consider short waves in a bunch of arbitrary profile. Both amplification of an external harmonic signal and SASE regime, i.e. selective amplification of proper noises, are investigated

Short term effects of kinesiotaping on acromiohumeral distance in asymptomatic subjects: a randomised controlled trial.

Science.gov (United States)

Luque-Suarez, A; Navarro-Ledesma, S; Petocz, P; Hancock, M J; Hush, J

2013-12-01

The first aim of this study was to investigate whether kinesiotaping (KT) can increase the acromiohumeral distance (AHD) in asymptomatic subjects in the short term. The second aim was to investigate whether the direction of kinesiotaping application influences AHD. In recent years, the use of KT has become increasingly popular for a range of musculoskeletal conditions and for sport injuries. To date, we are unaware of any research investigating the effect of kinesiotaping on AHD. Moreover, it is unknown whether the direction of kinesiotaping application for the shoulder is important. Forty nine participants were randomly assigned to one of three groups: kinesiotaping group 1 (KT1), kinesiotaping group 2 (KT2) and sham kinesiotaping (KT3). AHD ultrasound measurements at 0° and 60° of shoulder elevation were collected at baseline and immediately after kinesiotape application. The results showed significant improvements in AHD after kinesiotaping, compared with sham taping. The mean difference in AHD between KT1 and KT3 groups was 1.28 mm (95% CI: 0.55, 2.03), and between KT2 and KT3 was 0.98 mm (95% CI: 0.23, 1.74). Comparison of KT1 and KT2 groups, which was performed to identify whether the direction of taping influences the AHD, indicated there were no significant differences. KT increases AHD in healthy individuals immediately following application, compared with sham kinesiotape. No differences were found with respect to the direction in which KT was applied. Copyright © 2013 Elsevier Ltd. All rights reserved.

Hybrid rib-slot-rib plasmonic waveguide with deep-subwavelength mode confinement and long propagation length

Directory of Open Access Journals (Sweden)

Kai Zheng

2016-08-01

Full Text Available We propose a hybrid plasmonic waveguide where a combined rib-slot-rib structure is added on the metal substrate within a low-index gap region. The optical properties of the quasi-TM fundamental mode are numerically calculated using the finite element method. Compared to the traditional hybrid plasmonic waveguide, our designed waveguiding structure can support modes with tighter confinement and longer propagation length, by properly adjusting the geometry of the rib-slot-rib structure and the gap height. In details, it can provide the hybrid mode with mode area λ2/12000 and reasonable propagation distance 23.78 μm, simultaneously. Its excellent optical performance can facilitate potential applications in ultra-compact nanophotonic devices and circuits.

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

International Nuclear Information System (INIS)

Ribezzi-Crivellari, M.; Huguet, J. M.; Ritort, F.

2013-01-01

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.

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.

Propagator formalism and computer simulation of restricted diffusion behaviors of inter-molecular multiple-quantum coherences

International Nuclear Information System (INIS)

Cai Congbo; Chen Zhong; Cai Shuhui; Zhong Jianhui

2005-01-01

In this paper, behaviors of single-quantum coherences and inter-molecular multiple-quantum coherences under restricted diffusion in nuclear magnetic resonance experiments were investigated. The propagator formalism based on the loss of spin phase memory during random motion was applied to describe the diffusion-induced signal attenuation. The exact expression of the signal attenuation under the short gradient pulse approximation for restricted diffusion between two parallel plates was obtained using this propagator method. For long gradient pulses, a modified formalism was proposed. The simulated signal attenuation under the effects of gradient pulses of different width based on the Monte Carlo method agrees with the theoretical predictions. The propagator formalism and computer simulation can provide convenient, intuitive and precise methods for the study of the diffusion behaviors

Necessary conditions for the initiation and propagation of nuclear-detonation waves in plane atmospheres

International Nuclear Information System (INIS)

Weaver, T.A.; Wood, L.

1979-01-01

The basic conditions for the initiation of a nuclear-detonation wave in an atmosphere having plane symmetry (e.g., a thin, layered fluid envelope on a planet or star) are developed. Two classes of such a detonation are identified: those in which the temperature of the plasma is comparable to that of the electromagnetic radiation permeating it, and those in which the temperature of the plasma is much higher. Necessary conditions are developed for the propagation of such detonation waves for an arbitrarily great distance. The contribution of fusion chain reactions to these processes is evaluated. By means of these considerations, it is shown that neither the atmosphere nor oceans of the Earth may be made to undergo propagating nuclear detonation under any circumstances

Numerical and experimental study on atmospheric pressure ionization waves propagating through a U-shape channel

International Nuclear Information System (INIS)

Yan, Wen; Xia, Yang; Bi, Zhenhua; Song, Ying; Liu, Dongping; Wang, Dezhen; Sosnin, Eduard A; Skakun, Victor S

2017-01-01

A 2D computational study of ionization waves propagating in U-shape channels at atmospheric pressure was performed, with emphasis on the effect of voltage polarity and the curvature of the bend. The discharge was ignited by a HV needle electrode inside the channel, and power was applied in the form of a trapezoidal pulse lasting 2 µ s. We have shown that behavior of ionization waves propagating in U-shape channels was quite different with that in straight tubes. For positive polarity of applied voltage, the ionization waves tended to propagate along one side of walls rather than filling the channel. The propagation velocity of ionization waves predicted by the simulation was in good agreement with the experiment results; the velocity was first increasing rapidly in the vicinity of the needle tip and then decreasing with the increment of propagation distance. Then we have studied the influence of voltage polarity on discharge characteristics. For negative polarity, the ionization waves tended to propagate along the opposite side of the wall, while the discharge was more diffusive and volume-filling compared with the positive case. It was found that the propagation velocity for the negative ionization wave was higher than that for the positive one. Meanwhile, the propagation of the negative ionization wave depended less on the pre-ionization level than the positive ionization wave. Finally, the effect of the radius of curvature was studied. Simulations have shown that the propagation speeds were sensitive to the radii of the curvature of the channels for both polarities. Higher radii of curvature tended to have higher speed and longer length of plasma. The simulation results were supported by experimental observations under similar discharge conditions. (paper)

Heliocentric distance dependence of the interplanetary magnetic field

International Nuclear Information System (INIS)

Behannon, K.W.

1978-01-01

Recent and ongoing planetary missions have provided and are continuing to provide extensive observations of the variations of the interplanetary magnetic field (IMF) both in time and with heliocentric distance from the sun. Large time variations in both the IMF and its fluctuations are observed. These are produced predominantly by dynamical processes in the interplanetary medium associated with stream interactions. Magnetic field variations near the sun are propagated to greater heliocentric distances, a process also contributing to the observed variability of the IMF. Temporal variations on a time scale comparable to or less than the corotation period complicate attempts to deduce radial gradients of the field and its fluctuations from the various observations. However, recent measurements inward to 0.46 AU and outward to 5 AU suggest that the radial component of the field on average decreases approximately as r -2 , as was predicted by Parker, while the azimuthal component decreases more rapidly than the r -1 dependence predicted by simple theory. Three sets of observations are consistent with r/sup -1.3/ dependence for vertical-barB/sub phi/vertical-bar. The temporal variability of solar wind speed is most likely the predominant contributor to this latter observational result. The long-term average azimuthal component radial gradient is probably consistent with the Parker r -1 dependence when solar wind speed variations are taken into account. The observations of the normal component magnitude vertical-barB/sub theta/vertical-bar are roughly consistent with a heliocentric distance dependence of r/sup -1.4/. The observed radial distance dependence of the total magnitude of the IMF is well described by the Parker formulation. There is observational evidence that amplitudes of fluctuations of the vector field with periods less than 1 day vary with heliocentric distance as approximately r/sup -3/2/, in agreement with theoretical models by Whang and Hollweg

Subalpine bumble bee foraging distances and densities in relation to flower availability.

Science.gov (United States)

Elliott, Susan E

2009-06-01

Bees feed almost exclusively on nectar and pollen from flowers. However, little is known about how food availability limits bee populations, especially in high elevation areas. Foraging distances and relationships between forager densities and resource availability can provide insights into the potential for food limitation in mobile consumer populations. For example, if floral resources are limited, bee consumers should fly farther to forage, and they should be more abundant in areas with more flowers. I estimated subalpine bumble bee foraging distances by calculating forager recapture probabilities at increasing distances from eight marking locations. I measured forager and flower densities over the flowering season in six half-hectare plots. Because subalpine bumble bees have little time to build their colonies, they may forage over short distances and forager density may not be constrained by flower density. However, late in the season, when floral resources dwindle, foraging distances may increase, and there may be stronger relationships between forager and flower densities. Throughout the flowering season, marked bees were primarily found within 100 m (and never >1,000 m) from their original marking location, suggesting that they typically did not fly far to forage. Although the density of early season foraging queens increased with early-season flower density, the density of mid- and late-season workers and males did not vary with flower density. Short foraging distances and no relationships between mid- and late-season forager and flower densities suggest that high elevation bumble bees may have ample floral resources for colony growth reproduction.

Propagation speed and incident direction of transient ionospheric disturbance (TID)

International Nuclear Information System (INIS)

Maeda, Sawako; Handa, Shun.

1978-01-01

It is well known that large scale transient ionospheric disturbance (ls-TID) of period from 20 min to 3 hours and spatial wave length from hundreds to thousands km among TID's is in close correlation to geomagnetic activity at high latitude. Since TID well agrees with the wave characteristic of internal gravitational waves, it has come to be considered that the internal gravitational waves excited by Lorentz's force and joule heating due to the ionospheric current in auroral zone at the time of substorm cause disturbances to ionosphere electron density. The authors have examined the propagation speed and incident direction of TID using the data observed at 5 min intervals of maximum electron density in F layer during IGY (international geophysical year). The data was processed through a band pass filter because only the waves with period from 20 min to 3 hours were required. Since two proposed modes for ls-TID have been discussed, whose dispersion properties are different, it is necessary to determine the propagation characteristics of ls-TID by observation, and to clarify the propagation mechanism of internal gravitational waves. Therefore, the dependence of propagation speed on period has been investigated. It is concluded that ls-TID was observed at the time of polar magnetic field disturbances, the average propagation speed was about 500 m/s and the incident direction was north-north east for the variation of from 20 min to 3 hours, and as for the dependence of propagation speed on period, the average speed was about 670 m/s for the long period change (approximately 100 min period), and about 440 m/s for short period change (approximately 30 min period) and the dispersion was observed. (Wakatsuki, Y.)

Magnetic short range order and the exchange coupling in magnets

International Nuclear Information System (INIS)

Antropov, V.P.

2006-01-01

We discuss our recent results of time-dependent density functional simulations of magnetic properties of Fe and Ni at finite temperatures. These results indicated that a strong magnetic short range order is responsible for the magnetic properties of elementary Ni and any itinerant magnet in general. We demonstrated that one can use the value of the magnetic short range order parameter to produce new quantitative classification of magnets. We also discuss the nature of the exchange coupling and its connection with the short range order. The spin-wave like propagating and diffusive excitations in paramagnetic localized systems with small short range order have been predicted while in the itinerant systems the short range order is more complicated. The possible smallness of the quantum factor in the itinerant magnets with short range order is discussed

Propagation of three-dimensional bipolar ultrashort electromagnetic pulses in an inhomogeneous array of carbon nanotubes

Science.gov (United States)

Fedorov, Eduard G.; Zhukov, Alexander V.; Bouffanais, Roland; Timashkov, Alexander P.; Malomed, Boris A.; Leblond, Hervé; Mihalache, Dumitru; Rosanov, Nikolay N.; Belonenko, Mikhail B.

2018-04-01

We study the propagation of three-dimensional (3D) bipolar ultrashort electromagnetic pulses in an inhomogeneous array of semiconductor carbon nanotubes. The heterogeneity is represented by a planar region with an increased concentration of conduction electrons. The evolution of the electromagnetic field and electron concentration in the sample are governed by the Maxwell's equations and continuity equation. In particular, nonuniformity of the electromagnetic field along the axis of the nanotubes is taken into account. We demonstrate that depending on values of the parameters of the electromagnetic pulse approaching the region with the higher electron concentration, the pulse is either reflected from the region or passes it. Specifically, our simulations demonstrate that after interacting with the higher-concentration area, the pulse can propagate steadily, without significant spreading. The possibility of such ultrashort electromagnetic pulses propagating in arrays of carbon nanotubes over distances significantly exceeding characteristic dimensions of the pulses makes it possible to consider them as 3D solitons.

Part two: Error propagation

International Nuclear Information System (INIS)

Picard, R.R.

1989-01-01

Topics covered in this chapter include a discussion of exact results as related to nuclear materials management and accounting in nuclear facilities; propagation of error for a single measured value; propagation of error for several measured values; error propagation for materials balances; and an application of error propagation to an example of uranium hexafluoride conversion process

Sound transmission at ground level in a short-grass prairie habitat and its implications for long-range communication in the swift fox Vulpes velox

DEFF Research Database (Denmark)

Darden, Safi K; Pedersen, Simon B; Larsen, Ole N

2008-01-01

The acoustic environment of swift foxes Vulpes velox vocalizing close to the ground and the effect of propagation on individual identity information in vocalizations were quantified in a transmission experiment in prairie habitat. Sounds were propagated (0.45 m above the ground) at distances up t...

Pulsed positive corona streamer propagation and branching

International Nuclear Information System (INIS)

Veldhuizen, E.M. van; Rutgers, W.R.

2002-01-01

The propagation and branching of pulsed positive corona streamers in a short gap is observed with high resolution in space and time. The appearance of the pre-breakdown phenomena can be controlled by the electrode configuration, the gas composition and the impedance of the pulsed power circuit. In a point-wire gap the positive corona shows much more branching than in the parallel plane gap with a protrusion. In air, the branching is more pronounced than in argon. The pulsed power circuit appears to operate in two modes, either as an inductive circuit creating a lower number of thick streamers or as a resistive circuit giving a higher number of thin streamers. A possible cause for branching is electrostatic repulsion of two parts of the streamer head. The electric field at the streamer head is limited, the maximum values found are ∼170 kV cm -1 in air and ∼100 kV cm -1 in argon. At these maximum field strengths, the electrons have 5-10 eV energy, so the ionization is dominated by two-step processes. Differences between argon and ambient air in the field strength at which streamers propagate are ascribed to the difference in de-excitation processes in noble and molecular gases. The fact that the pulsed power circuit can control the streamer structure is important for applications, but this effect must also be taken into account in fundamental studies of streamer propagation and branching. (author)

Pulsed positive corona streamer propagation and branching

Energy Technology Data Exchange (ETDEWEB)

Veldhuizen, E.M. van [Department of Physics, Technische Universiteit Eindhoven, Eindhoven (Netherlands)]. E-mail: e.m.v.veldhuizen@tue.nl; Rutgers, W.R. [Department of Physics, Technische Universiteit Eindhoven, Eindhoven (Netherlands)

2002-09-07

The propagation and branching of pulsed positive corona streamers in a short gap is observed with high resolution in space and time. The appearance of the pre-breakdown phenomena can be controlled by the electrode configuration, the gas composition and the impedance of the pulsed power circuit. In a point-wire gap the positive corona shows much more branching than in the parallel plane gap with a protrusion. In air, the branching is more pronounced than in argon. The pulsed power circuit appears to operate in two modes, either as an inductive circuit creating a lower number of thick streamers or as a resistive circuit giving a higher number of thin streamers. A possible cause for branching is electrostatic repulsion of two parts of the streamer head. The electric field at the streamer head is limited, the maximum values found are {approx}170 kV cm{sup -1} in air and {approx}100 kV cm{sup -1} in argon. At these maximum field strengths, the electrons have 5-10 eV energy, so the ionization is dominated by two-step processes. Differences between argon and ambient air in the field strength at which streamers propagate are ascribed to the difference in de-excitation processes in noble and molecular gases. The fact that the pulsed power circuit can control the streamer structure is important for applications, but this effect must also be taken into account in fundamental studies of streamer propagation and branching. (author)

An eastward propagating compressional Pc 5 wave observed by AMPTE/CCE in the postmidnight sector

International Nuclear Information System (INIS)

Takahashi, K.; McEntire, R.W.; Zanetti, L.J.; Lopez, R.E.; Kistler, L.M.; Ipavich, R.M.

1987-01-01

Data from three instruments, the magnetometer, the charge-energy-mass spectrometer, and the medium-energy particle analyzer onboard the Active Magnetospheric Particle Tracer Explorers/Charge Composition Explorer (CCE) spacecraft have been used to study a compressional Pc 5 wave observed at 1925-2200 UT on day 202 (July 21) of 1986 at a radial distance of ≅ 8 R E in the postmidnight sector near the beginning of minor geomagnetic activity. The wave exhibited harmonically related transverse and compressional magnetic oscillations, modulation of the flux of medium energy protons (E approx-gt 10 keV), and a large azimuthal wave number (m ∼ 65). These properties are similar to those of compressional Pc 5 waves observed previously at geostationary orbit. The unique observations associated with the CCE event are the occurrence in the postmidnight sector, the eastward (or sunward) propagation with respect to the spacecraft, and the left-handed polarization of the perturbed magnetic field. These are opposite to previous geostationary observations. The authors propose that the unique propagation and polarization are propagating westward in the plasma rest frame, appears to propagate eastward to the observer because the electric field drift velocity is larger than the wave phase velocity

Generating high-power short terahertz electromagnetic pulses with a multifoil radiator.

Science.gov (United States)

Vinokurov, Nikolay A; Jeong, Young Uk

2013-02-08

We describe a multifoil cone radiator capable of generating high-field short terahertz pulses using short electron bunches. Round flat conducting foil plates with successively decreasing radii are stacked, forming a truncated cone with the z axis. The gaps between the foil plates are equal and filled with some dielectric (or vacuum). A short relativistic electron bunch propagates along the z axis. At sufficiently high particle energy, the energy losses and multiple scattering do not change the bunch shape significantly. When passing by each gap between the foil plates, the electron bunch emits some energy into the gap. Then, the radiation pulses propagate radially outward. For transverse electromagnetic waves with a longitudinal (along the z axis) electric field and an azimuthal magnetic field, there is no dispersion in these radial lines; therefore, the radiation pulses conserve their shapes (time dependence). At the outer surface of the cone, we have synchronous circular radiators. Their radiation field forms a conical wave. Ultrashort terahertz pulses with gigawatt-level peak power can be generated with this device.

Diversity and Stability of Lactic Acid Bacteria in Rye Sourdoughs of Four Bakeries with Different Propagation Parameters.

Directory of Open Access Journals (Sweden)

Ene Viiard

Full Text Available We identified the lactic acid bacteria within rye sourdoughs and starters from four bakeries with different propagation parameters and tracked their dynamics for between 5-28 months after renewal. Evaluation of bacterial communities was performed using plating, denaturing gradient gel electrophoresis, and pyrosequencing of 16S rRNA gene amplicons. Lactobacillus amylovorus and Lactobacillus frumenti or Lactobacillus helveticus, Lactobacillus pontis and Lactobacillus panis prevailed in sourdoughs propagated at higher temperature, while ambient temperature combined with a short fermentation cycle selected for Lactobacillus sanfranciscensis, Lactobacillus pontis, and Lactobacillus zymae or Lactobacillus helveticus, Lactobacillus pontis and Lactobacillus zymae. The ratio of species in bakeries employing room-temperature propagation displayed a seasonal dependence. Introduction of different and controlled propagation parameters at one bakery (higher fermentation temperature, reduced inoculum size, and extended fermentation time resulted in stabilization of the microbial community with an increased proportion of L. helveticus and L. pontis. Despite these new propagation parameters no new species were detected.

Memory retrieval as a self-propagating process.

Science.gov (United States)

Bäuml, Karl-Heinz T; Schlichting, Andreas

2014-07-01

Retrieval of a subset of studied items and the presentation of those items as retrieval cues typically impair retrieval of the other items. Previous research on this self-limiting property of memory retrieval has relied heavily on short retention intervals and similar context between encoding and test. Here, we examined retrieval dynamics also after a prolonged retention interval with different spatial and social context between encoding and test, conditions that mimic people's remembering in many situations of daily life. For both unrelated word lists and more integrated prose material, we found retrieval and cuing to impair recall of other studied items after a short retention interval, but to improve recall in the prolonged retention interval condition. The results demonstrate that retrieval dynamics depend critically on situation, indicating that quite often in daily life, retrieval may be a self-propagating, rather than a self-limiting process. Copyright © 2014 Elsevier B.V. All rights reserved.

8th conference on Ultra-Wideband Short-Pulse Electromagnetics

CERN Document Server

Tyo, J. Scott; Baum, Carl E; Ultra-Wideband Short-Pulse Electromagnetics 8; UWBSP8

2007-01-01

The purpose of the Ultra-Wideband Short-Pulse Electromagnetics Conference series is to focus on advanced technologies for the generation, radiation and detection of ultra-wideband short pulse signals, taking into account their propagation and scattering from and coupling to targets of interest. This Conference series reports on developments in supporting mathematical and numerical methods and presents current and potential future applications of the technology. Ultra-Wideband Short-Pulse Electromagnetics 8 is based on the American Electromagnetics 2006 conference held from June 3-7 in Albuquerque, New Mexico. Topical areas covered in this volume include pulse radiation and measurement, scattering theory, target detection and identification, antennas, signal processing, and communications.

Studies on the mechanism of replication of adenovirus DNA. IV. Discontinuous DNA chain propagation

NARCIS (Netherlands)

Vlak, J.M.; Rozijn, Th.H.; Sussenbach, J.S.

The replication of adenovirus type 5 DNA occurs by discontinuous chain propagation via short pieces of DNA. These pieces accumulate if the infected cells are treated with hydroxyurea. They have a sedimentation coefficient of 11 S corresponding to a molecular weight of about 700,000, and they contain

Determining the Viscosity Coefficient for Viscoelastic Wave Propagation in Rock Bars

Science.gov (United States)

Niu, Leilei; Zhu, Wancheng; Li, Shaohua; Guan, Kai

2018-05-01

Rocks with microdefects exhibit viscoelastic behavior during stress wave propagation. The viscosity coefficient of the wave can be used to characterize the attenuation as the wave propagates in rock. In this study, a long artificial bar with a readily adjustable viscosity coefficient was fabricated to investigate stress wave attenuation. The viscoelastic behavior of the artificial bar under dynamic loading was investigated, and the initial viscoelastic coefficient was obtained based on the amplitude attenuation of the incident harmonic wave. A one-dimensional wave propagation program was compiled to reproduce the time history of the stress wave measured during the experiments, and the program was well fitted to the Kelvin-Voigt model. The attenuation and dispersion of the stress wave in long artificial viscoelastic bars were quantified to accurately determine the viscoelastic coefficient. Finally, the method used to determine the viscoelastic coefficient of a long artificial bar based on the experiments and numerical simulations was extended to determine the viscoelastic coefficient of a short rock bar. This study provides a new method of determining the viscosity coefficient of rock.

Propagation speed of gamma radiation in brass

International Nuclear Information System (INIS)

Cavalcante, Jose T.P.D.; Silva, Paulo R.J.; Saitovich, Henrique

2009-01-01

The propagation speed (PS) of visible light -represented by a short frequency range in the large frame of electromagnetic radiations (ER) frequencies- in air was measured during the last century, using a great deal of different methods, with high precision results being achieved. Presently, a well accepted value, with very small uncertainty, is c= 299,792.458 Km/s) (c reporting to the Latin word celeritas: 'speed swiftness'). When propagating in denser material media (MM), such value is always lower when compared to the air value, with the propagating MM density playing an important role. Until present, such studies focusing propagation speeds, refractive indexes, dispersions were specially related to visible light, or to ER in wavelengths ranges dose to it, and with a transparent MM. A first incursion in this subject dealing with γ-rays was performed using an electronic coincidence counting system, when the value of it's PS was measured in air, C γ(air) 298,300.15 Km/s; a method that went on with later electronic improvements. always in air. To perform such measurements the availability of a γ-radiation source in which two γ-rays are emitted simultaneously in opposite directions -as already used as well as applied in the present case- turns out to be essential to the feasibility of the experiment, as far as no reflection techniques could be used. Such a suitable source was the positron emitter 22 Na placed in a thin wall metal container in which the positrons are stopped and annihilated when reacting with the medium electrons, in such way originating -as it is very well established from momentum/energy conservation laws - two gamma-rays, energy 511 KeV each, both emitted simultaneously in opposite directions. In all the previous experiments were used photomultiplier detectors coupled to NaI(Tl) crystal scintillators, which have a good energy resolution but a deficient time resolution for such purposes. Presently, as an innovative improvement, were used BaF 2

In Vitro Propagation and Conservation of Bacopa monnieri L.

Science.gov (United States)

Sharma, Neelam; Singh, Rakesh; Pandey, Ruchira

2016-01-01

Bacopa monnieri L. (common name brahmi) is a traditional and renowned Indian medicinal plant with high commercial value for its memory revitalizer potential. Demand for this herb has further escalated due to popularization of various brahmi-based drugs coupled with reported anticancer property. Insufficient seed availability and problems associated with seed propagation including short seed viability are the major constraints of seed conservation in the gene banks. In vitro clonal propagation, a prerequisite for in vitro conservation by enhanced axillary branching was standardized. We have developed a simple, single step protocol for in vitro establishment, propagation and medium-term conservation of B. monnieri. Single node explants, cultured on Murashige and Skoog's medium supplemented with BA (0.2 mg/L), exhibited shoot proliferation without callus formation. Rooting was achieved on the same medium. The in vitro raised plants were successfully transferred to soil with ~80 % survival. On the same medium, shoots could also be conserved for 12 months with high survival and genetic stability was maintained as revealed by molecular markers. The protocol optimized in the present study has been applied for culture establishment, shoot multiplication and medium-term conservation of several Bacopa germplasm, procured from different agro-ecological regions of India.

Temporal scaling in information propagation

Science.gov (United States)

Huang, Junming; Li, Chao; Wang, Wen-Qiang; Shen, Hua-Wei; Li, Guojie; Cheng, Xue-Qi

2014-06-01

For the study of information propagation, one fundamental problem is uncovering universal laws governing the dynamics of information propagation. This problem, from the microscopic perspective, is formulated as estimating the propagation probability that a piece of information propagates from one individual to another. Such a propagation probability generally depends on two major classes of factors: the intrinsic attractiveness of information and the interactions between individuals. Despite the fact that the temporal effect of attractiveness is widely studied, temporal laws underlying individual interactions remain unclear, causing inaccurate prediction of information propagation on evolving social networks. In this report, we empirically study the dynamics of information propagation, using the dataset from a population-scale social media website. We discover a temporal scaling in information propagation: the probability a message propagates between two individuals decays with the length of time latency since their latest interaction, obeying a power-law rule. Leveraging the scaling law, we further propose a temporal model to estimate future propagation probabilities between individuals, reducing the error rate of information propagation prediction from 6.7% to 2.6% and improving viral marketing with 9.7% incremental customers.

Optimization of the working distance of an ion microprobe-forming system

International Nuclear Information System (INIS)

Melnik, K.I.; Magilin, D.V.; Ponomarev, A.G.

2009-01-01

A high-resolution ion microprobe necessitates the use of a small working distance (the distance from the final quadrupole lens of a probe-forming system to the specimen) in order to produce a large demagnification. But at the same time a small working distance is a source of a number of practical difficulties. We have presented an approach for determining a working distance that provides the best spatial resolution with the main practical limitations taken into account. We used a probe-forming system acceptance as a criterion of optimality. The calculations have revealed the existence of an optimal working distance in a set of common probe-forming systems, but it can be achieved only after changing of a design of a final quadrupole lens. We proposed a possible design of conic lens that allows solving the problem of detectors location and creating a short focus system. Three-dimensional calculations of magnetic field within this lens predicted a good quality of field structure.

STUDY OF THE PROPAGATION OF SHORT PULSE LASER WITH CAVITY USING NUMERICAL SIMULATION SOFTWARE

Directory of Open Access Journals (Sweden)

S. Terniche

2015-07-01

Full Text Available The purpose of this representation is to show the potentialities (Computational Time, access to the dynamic and feasibility of systematic studies of the numerical study of the nonlinear dynamics in laser cavity, assisted by software. We will give as an example, one type of cavity completely fibered composed of several elements and then studying the physical parameters of a pulse propagating into this cavity, determining its characteristics at the output. The results are interesting but we also projects to verify them experimentally by making assemblies similar to this type of cavities.

A Study of RF Link and Coverage in ZigBee

Directory of Open Access Journals (Sweden)

Doru Suciu

2010-06-01

Full Text Available To implement a ZigBee network, wave propagation models are necessary to determine propagation characteristics for installation of these short-range networks of industrial, scientific, and medical (ISM applications but also consumer electronics and smart home appliances. Most applications are deployed indoor, so a very large variety of situations will be met. Using propagations models for indoor environment, the distances between nodes for a reliable RF link, using standard ZigBee devices were determined.

Long Range Sound Propagation over Sea: Application to Wind Turbine Noise

Energy Technology Data Exchange (ETDEWEB)

Boue, Matieu

2007-12-13

The classical theory of spherical wave propagation is not valid at large distances from a sound source due to the influence of wind and temperature gradients that refract, i.e., bend the sound waves. This will in the downwind direction lead to a cylindrical type of wave spreading for large distances (> 1 km). Cylindrical spreading will give a smaller damping with distance as compared to spherical spreading (3 dB/distance doubling instead of 6 dB). But over areas with soft ground, i.e., grass land, the effect of ground reflections will increase the damping so that, if the effect of atmospheric damping is removed, a behavior close to a free field spherical spreading often is observed. This is the standard assumption used in most national recommendations for predicting outdoor sound propagation, e.g., noise from wind turbines. Over areas with hard surfaces, e.g., desserts or the sea, the effect of ground damping is small and therefore cylindrical propagation could be expected in the downwind direction. This observation backed by a limited number of measurements is the background for the Swedish recommendation, which suggests that cylindrical wave spreading should be assumed for distances larger than 200 m for sea based wind turbines. The purpose of this work was to develop measurement procedures for long range sound transmission and to apply this to investigate the occurrence of cylindrical wave spreading in the Baltic Sea. This work has been successfully finished and is described in this report. Another ambition was to develop models for long range sound transmission based on the parabolic equation. Here the work is not finished but must be continued in another project. Long term measurements were performed in the Kalmar strait, Sweden, located between the mainland and Oeland, during 2005 and 2006. Two different directive sound sources placed on a lighthouse in the middle of the strait produced low frequency tones at 80, 200 and 400 Hz. At the reception point on

Trends and Issues in Distance Education: International Perspectives

Directory of Open Access Journals (Sweden)

Erhan EROGLU

2006-04-01

��quality, accredition and recognition: issues in the delivery of transnational education.” Third perspective is “the long and short of distance education: trends and issues from a planetary human develeopment perspective.” Fourth perspective is “distance education reappraised: emerging trends in traditional universities and corporate training institutions.” And fifth one is “what the world needs now: international research on distance education.” Part II contains a series of interviews that that were conducted with international distance education leaders. This section has four chapters. The individuals interviewes in this section were selected because they have played a significant role in the development of distance education theory, research and practice. Part III of the book presents a fascinating array of case studies in distance education. This section has eight chapters. The chapters in Part III section of the book cover experiences with programs and initiatives in places as diverse as South Africa, Brazil, and Turkey. Some of these case studies report on experience with in a specific nation. Part IV, the last part of the book, focuses on practical issues in distance education. In tih section, there are three chapters. In this section, authors of the chapters discuss some of the key trends in the design and development of distance education for international audiences and settings. For example, “wide array of technologies and strategies that can be used for distance education, while giving special consideration to the impact of human and environmental differences on the selection of approaches”, “analysing of how mentoring roles evolve as the technologies enabling distance learning become increasingly interactive and accomodating of student-to-student and student-to-instructor interaction. CONTENTS OF THE BOOK Introduction Yusra Laila VISSER, Lya VISSER, Michael SIMONSON, and Ray Amirault PART I PERSPECTIVES ON GLOBAL TRENDS AND ISSUES IN DISTANCE EDUCATION A

Dependency distance: A new perspective on syntactic patterns in natural languages.

Science.gov (United States)

Liu, Haitao; Xu, Chunshan; Liang, Junying

2017-07-01

Dependency distance, measured by the linear distance between two syntactically related words in a sentence, is generally held as an important index of memory burden and an indicator of syntactic difficulty. Since this constraint of memory is common for all human beings, there may well be a universal preference for dependency distance minimization (DDM) for the sake of reducing memory burden. This human-driven language universal is supported by big data analyses of various corpora that consistently report shorter overall dependency distance in natural languages than in artificial random languages and long-tailed distributions featuring a majority of short dependencies and a minority of long ones. Human languages, as complex systems, seem to have evolved to come up with diverse syntactic patterns under the universal pressure for dependency distance minimization. However, there always exist a small number of long-distance dependencies in natural languages, which may reflect some other biological or functional constraints. Language system may adapt itself to these sporadic long-distance dependencies. It is these universal constraints that have shaped such a rich diversity of syntactic patterns in human languages. Copyright © 2017. Published by Elsevier B.V.

Experimental and theoretical studies of near-ground acoustic radiation propagation in the atmosphere

Science.gov (United States)

Belov, Vladimir V.; Burkatovskaya, Yuliya B.; Krasnenko, Nikolai P.; Rakov, Aleksandr S.; Rakov, Denis S.; Shamanaeva, Liudmila G.

2017-11-01

Results of experimental and theoretical studies of the process of near-ground propagation of monochromatic acoustic radiation on atmospheric paths from a source to a receiver taking into account the contribution of multiple scattering on fluctuations of atmospheric temperature and wind velocity, refraction of sound on the wind velocity and temperature gradients, and its reflection by the underlying surface for different models of the atmosphere depending the sound frequency, coefficient of reflection from the underlying surface, propagation distance, and source and receiver altitudes are presented. Calculations were performed by the Monte Carlo method using the local estimation algorithm by the computer program developed by the authors. Results of experimental investigations under controllable conditions are compared with theoretical estimates and results of analytical calculations for the Delany-Bazley impedance model. Satisfactory agreement of the data obtained confirms the correctness of the suggested computer program.

Third harmonic generation of shear horizontal guided waves propagation in plate-like structures

Energy Technology Data Exchange (ETDEWEB)

Li, Wei Bin [School of Aerospace Engineering, Xiamen University, Xiamen (China); Xu, Chun Guang [School of Mechanical Engineering, Beijing Institute of Technology, Beijing (China); Cho, Youn Ho [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)

2016-04-15

The use of nonlinear ultrasonics wave has been accepted as a promising tool for monitoring material states related to microstructural changes, as it has improved sensitivity compared to conventional non-destructive testing approaches. In this paper, third harmonic generation of shear horizontal guided waves propagating in an isotropic plate is investigated using the perturbation method and modal analysis approach. An experimental procedure is proposed to detect the third harmonics of shear horizontal guided waves by electromagnetic transducers. The strongly nonlinear response of shear horizontal guided waves is measured. The accumulative growth of relative acoustic nonlinear response with an increase of propagation distance is detected in this investigation. The experimental results agree with the theoretical prediction, and thus providing another indication of the feasibility of using higher harmonic generation of electromagnetic shear horizontal guided waves for material characterization.

Observations of short gamma-ray bursts.

Science.gov (United States)

Fox, Derek B; Roming, Peter W A

2007-05-15

We review recent observations of short-hard gamma-ray bursts and their afterglows. The launch and successful ongoing operations of the Swift satellite, along with several localizations from the High-Energy Transient Explorer mission, have provoked a revolution in short-burst studies: first, by quickly providing high-quality positions to observers; and second, via rapid and sustained observations from the Swift satellite itself. We make a complete accounting of Swift-era short-burst localizations and proposed host galaxies, and discuss the implications of these observations for the distances, energetics and environments of short bursts, and the nature of their progenitors. We then review the physical modelling of short-burst afterglows: while the simplest afterglow models are inadequate to explain the observations, there have been several notable successes. Finally, we address the case of an unusual burst that threatens to upset the simple picture in which long bursts are due to the deaths of massive stars, and short bursts to compact-object merger events.

Propagation of high power electromagnetic beam in relativistic magnetoplasma: Higher order paraxial ray theory

Science.gov (United States)

Gill, Tarsem Singh; Kaur, Ravinder; Mahajan, Ranju

2010-09-01

This paper presents an analysis of self-consistent, steady-state, theoretical model, which explains the ring formation in a Gaussian electromagnetic beam propagating in a magnetoplasma, characterized by relativistic nonlinearity. Higher order terms (up to r4) in the expansion of the dielectric function and the eikonal have been taken into account. The condition for the formation of a dark and bright ring derived earlier by Misra and Mishra [J. Plasma Phys. 75, 769 (2009)] has been used to study focusing/defocusing of the beam. It is seen that inclusion of higher order terms does significantly affect the dependence of the beam width on the distance of propagation. Further, the effect of the magnetic field and the nature of nonlinearity on the ring formation and self-focusing of the beam have been explored.

Propagation of high power electromagnetic beam in relativistic magnetoplasma: Higher order paraxial ray theory

International Nuclear Information System (INIS)

Gill, Tarsem Singh; Kaur, Ravinder; Mahajan, Ranju

2010-01-01

This paper presents an analysis of self-consistent, steady-state, theoretical model, which explains the ring formation in a Gaussian electromagnetic beam propagating in a magnetoplasma, characterized by relativistic nonlinearity. Higher order terms (up to r 4 ) in the expansion of the dielectric function and the eikonal have been taken into account. The condition for the formation of a dark and bright ring derived earlier by Misra and Mishra [J. Plasma Phys. 75, 769 (2009)] has been used to study focusing/defocusing of the beam. It is seen that inclusion of higher order terms does significantly affect the dependence of the beam width on the distance of propagation. Further, the effect of the magnetic field and the nature of nonlinearity on the ring formation and self-focusing of the beam have been explored.

Discovery of Ubiquitous Fast-Propagating Intensity Disturbances by the Chromospheric Lyman Alpha Spectropolarimeter (CLASP)

Science.gov (United States)

Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando, T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G.; Tsuneta, S.; Ishikawa, S.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.; Auchère, F.; Trujillo Bueno, J.; Asensio Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M.

2016-12-01

High-cadence observations by the slit-jaw (SJ) optics system of the sounding rocket experiment known as the Chromospheric Lyman Alpha Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances that recurrently propagate in either the chromosphere or the transition region or both at a speed much higher than the speed of sound. The CLASP/SJ instrument provides a time series of two-dimensional images taken with broadband filters centered on the Lyα line at a 0.6 s cadence. The multiple fast-propagating intensity disturbances appear in the quiet Sun and in an active region, and they are clearly detected in at least 20 areas in a field of view of 527″ × 527″ during the 5 minute observing time. The apparent speeds of the intensity disturbances range from 150 to 350 km s-1, and they are comparable to the local Alfvén speed in the transition region. The intensity disturbances tend to propagate along bright elongated structures away from areas with strong photospheric magnetic fields. This suggests that the observed fast-propagating intensity disturbances are related to the magnetic canopy structures. The maximum distance traveled by the intensity disturbances is about 10″, and the widths are a few arcseconds, which are almost determined by a pixel size of 1.″03. The timescale of each intensity pulse is shorter than 30 s. One possible explanation for the fast-propagating intensity disturbances observed by CLASP is magnetohydrodynamic fast-mode waves.

DISCOVERY OF UBIQUITOUS FAST-PROPAGATING INTENSITY DISTURBANCES BY THE CHROMOSPHERIC LYMAN ALPHA SPECTROPOLARIMETER (CLASP)

International Nuclear Information System (INIS)

Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando, T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G.; Tsuneta, S.; Ishikawa, S.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.; Auchère, F.; Bueno, J. Trujillo; Ramos, A. Asensio

2016-01-01

High-cadence observations by the slit-jaw (SJ) optics system of the sounding rocket experiment known as the Chromospheric Lyman Alpha Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances that recurrently propagate in either the chromosphere or the transition region or both at a speed much higher than the speed of sound. The CLASP/SJ instrument provides a time series of two-dimensional images taken with broadband filters centered on the Ly α line at a 0.6 s cadence. The multiple fast-propagating intensity disturbances appear in the quiet Sun and in an active region, and they are clearly detected in at least 20 areas in a field of view of 527″ × 527″ during the 5 minute observing time. The apparent speeds of the intensity disturbances range from 150 to 350 km s −1 , and they are comparable to the local Alfvén speed in the transition region. The intensity disturbances tend to propagate along bright elongated structures away from areas with strong photospheric magnetic fields. This suggests that the observed fast-propagating intensity disturbances are related to the magnetic canopy structures. The maximum distance traveled by the intensity disturbances is about 10″, and the widths are a few arcseconds, which are almost determined by a pixel size of 1.″03. The timescale of each intensity pulse is shorter than 30 s. One possible explanation for the fast-propagating intensity disturbances observed by CLASP is magnetohydrodynamic fast-mode waves.

Analysis of Seasonal Signal in GPS Short-Baseline Time Series

Science.gov (United States)

Wang, Kaihua; Jiang, Weiping; Chen, Hua; An, Xiangdong; Zhou, Xiaohui; Yuan, Peng; Chen, Qusen

2018-04-01

Proper modeling of seasonal signals and their quantitative analysis are of interest in geoscience applications, which are based on position time series of permanent GPS stations. Seasonal signals in GPS short-baseline (paper, to better understand the seasonal signal in GPS short-baseline time series, we adopted and processed six different short-baselines with data span that varies from 2 to 14 years and baseline length that varies from 6 to 1100 m. To avoid seasonal signals that are overwhelmed by noise, each of the station pairs is chosen with significant differences in their height (> 5 m) or type of the monument. For comparison, we also processed an approximately zero baseline with a distance of pass-filtered (BP) noise is valid for approximately 40% of the baseline components, and another 20% of the components can be best modeled by a combination of the first-order Gauss-Markov (FOGM) process plus white noise (WN). The TEM displacements are then modeled by considering the monument height of the building structure beneath the GPS antenna. The median contributions of TEM to the annual amplitude in the vertical direction are 84% and 46% with and without additional parts of the monument, respectively. Obvious annual signals with amplitude > 0.4 mm in the horizontal direction are observed in five short-baselines, and the amplitudes exceed 1 mm in four of them. These horizontal seasonal signals are likely related to the propagation of daily/sub-daily TEM displacement or other signals related to the site environment. Mismodeling of the tropospheric delay may also introduce spurious seasonal signals with annual amplitudes of 5 and 2 mm, respectively, for two short-baselines with elevation differences greater than 100 m. The results suggest that the monument height of the additional part of a typical GPS station should be considered when estimating the TEM displacement and that the tropospheric delay should be modeled cautiously, especially with station pairs with

Study on Effectiveness of the chaos laser radar

OpenAIRE

成田, 義之; 津田, 紀生; 山田, 諄

2003-01-01

A laser is widely applied for measurements, since it is invented. There are two types of laser distance meter for short and long distance. For long distance, a laser radar using propagation time of laser light is used. Generally, a distance is measured from delay time using either a periodic signal or a single pulse. But the signal becomes to be buried in noise with increasing distance. A new type of chaos laser radar which processes by only an addition is proposed. This radar can quickly pro...

Short-time quantum dynamics of sharp boundaries potentials

Energy Technology Data Exchange (ETDEWEB)

Granot, Er' el, E-mail: erel@ariel.ac.il; Marchewka, Avi

2015-02-15

Despite the high prevalence of singular potential in general, and rectangular potentials in particular, in applied scattering models, to date little is known about their short time effects. The reason is that singular potentials cause a mixture of complicated local as well as non-local effects. The object of this work is to derive a generic method to calculate analytically the short-time impact of any singular potential. In this paper it is shown that the scattering of a smooth wavefunction on a singular potential is totally equivalent, in the short-time regime, to the free propagation of a singular wavefunction. However, the latter problem was totally addressed analytically in Ref. [7]. Therefore, this equivalency can be utilized in solving analytically the short time dynamics of any smooth wavefunction at the presence of a singular potentials. In particular, with this method the short-time dynamics of any problem where a sharp boundaries potential (e.g., a rectangular barrier) is turned on instantaneously can easily be solved analytically.

Short-time quantum dynamics of sharp boundaries potentials

Science.gov (United States)

Granot, Er'el; Marchewka, Avi

2015-02-01

Despite the high prevalence of singular potential in general, and rectangular potentials in particular, in applied scattering models, to date little is known about their short time effects. The reason is that singular potentials cause a mixture of complicated local as well as non-local effects. The object of this work is to derive a generic method to calculate analytically the short-time impact of any singular potential. In this paper it is shown that the scattering of a smooth wavefunction on a singular potential is totally equivalent, in the short-time regime, to the free propagation of a singular wavefunction. However, the latter problem was totally addressed analytically in Ref. [7]. Therefore, this equivalency can be utilized in solving analytically the short time dynamics of any smooth wavefunction at the presence of a singular potentials. In particular, with this method the short-time dynamics of any problem where a sharp boundaries potential (e.g., a rectangular barrier) is turned on instantaneously can easily be solved analytically.

Short-time quantum dynamics of sharp boundaries potentials

International Nuclear Information System (INIS)

Granot, Er'el; Marchewka, Avi

2015-01-01

Despite the high prevalence of singular potential in general, and rectangular potentials in particular, in applied scattering models, to date little is known about their short time effects. The reason is that singular potentials cause a mixture of complicated local as well as non-local effects. The object of this work is to derive a generic method to calculate analytically the short-time impact of any singular potential. In this paper it is shown that the scattering of a smooth wavefunction on a singular potential is totally equivalent, in the short-time regime, to the free propagation of a singular wavefunction. However, the latter problem was totally addressed analytically in Ref. [7]. Therefore, this equivalency can be utilized in solving analytically the short time dynamics of any smooth wavefunction at the presence of a singular potentials. In particular, with this method the short-time dynamics of any problem where a sharp boundaries potential (e.g., a rectangular barrier) is turned on instantaneously can easily be solved analytically

Solar wind stream evolution at large heliocentric distances - Experimental demonstration and the test of a model

Science.gov (United States)

Gosling, J. T.; Hundhausen, A. J.; Bame, S. J.

1976-01-01

A stream propagation model which neglects all dissipation effects except those occurring at shock interfaces, was used to compare Pioneer-10 solar wind speed observations, during the time when Pioneer 10, the earth, and the sun were coaligned, with near-earth Imp-7 observations of the solar wind structure, and with the theoretical predictions of the solar wind structure at Pioneer 10 derived from the Imp-7 measurements, using the model. The comparison provides a graphic illustration of the phenomenon of stream steepening in the solar wind with the attendant formation of forward-reverse shock pairs and the gradual decay of stream amplitudes with increasing heliocentric distance. The comparison also provides a qualitative test of the stream propagation model.

Propagation of uncertainty by Monte Carlo simulations in case of basic geodetic computations

Directory of Open Access Journals (Sweden)

Wyszkowska Patrycja

2017-12-01

Full Text Available The determination of the accuracy of functions of measured or adjusted values may be a problem in geodetic computations. The general law of covariance propagation or in case of the uncorrelated observations the propagation of variance (or the Gaussian formula are commonly used for that purpose. That approach is theoretically justified for the linear functions. In case of the non-linear functions, the first-order Taylor series expansion is usually used but that solution is affected by the expansion error. The aim of the study is to determine the applicability of the general variance propagation law in case of the non-linear functions used in basic geodetic computations. The paper presents errors which are a result of negligence of the higher-order expressions and it determines the range of such simplification. The basis of that analysis is the comparison of the results obtained by the law of propagation of variance and the probabilistic approach, namely Monte Carlo simulations. Both methods are used to determine the accuracy of the following geodetic computations: the Cartesian coordinates of unknown point in the three-point resection problem, azimuths and distances of the Cartesian coordinates, height differences in the trigonometric and the geometric levelling. These simulations and the analysis of the results confirm the possibility of applying the general law of variance propagation in basic geodetic computations even if the functions are non-linear. The only condition is the accuracy of observations, which cannot be too low. Generally, this is not a problem with using present geodetic instruments.

Propagation of uncertainty by Monte Carlo simulations in case of basic geodetic computations

Science.gov (United States)

Wyszkowska, Patrycja

2017-12-01

The determination of the accuracy of functions of measured or adjusted values may be a problem in geodetic computations. The general law of covariance propagation or in case of the uncorrelated observations the propagation of variance (or the Gaussian formula) are commonly used for that purpose. That approach is theoretically justified for the linear functions. In case of the non-linear functions, the first-order Taylor series expansion is usually used but that solution is affected by the expansion error. The aim of the study is to determine the applicability of the general variance propagation law in case of the non-linear functions used in basic geodetic computations. The paper presents errors which are a result of negligence of the higher-order expressions and it determines the range of such simplification. The basis of that analysis is the comparison of the results obtained by the law of propagation of variance and the probabilistic approach, namely Monte Carlo simulations. Both methods are used to determine the accuracy of the following geodetic computations: the Cartesian coordinates of unknown point in the three-point resection problem, azimuths and distances of the Cartesian coordinates, height differences in the trigonometric and the geometric levelling. These simulations and the analysis of the results confirm the possibility of applying the general law of variance propagation in basic geodetic computations even if the functions are non-linear. The only condition is the accuracy of observations, which cannot be too low. Generally, this is not a problem with using present geodetic instruments.

Electron dynamics inside short-coherence systems

International Nuclear Information System (INIS)

Ferrari, Giulio; Bordone, Paolo; Jacoboni, Carlo

2006-01-01

We present theoretical results on electron dynamics inside nanometric systems, where the coherence of the electron ensemble is maintained in a very short region. The contacts are supposed to spoil such a coherence, therefore the interference processes between the carrier wavefunction and the internal potential profile can be affected by the proximity of the contacts. The problem has been analysed by using the Wigner-function formalism. For very short devices, transport properties, such as tunnelling through potential barriers, are significantly influenced by the distance between the contacts

Experiments on leak-selfwastage and leak-propagation

International Nuclear Information System (INIS)

Voss, J.; Vagt, P.; Westenbrugge, J.K. van; Joziasse, J.

1984-01-01

During the last years a considerable number of selfwastage experiments with small leaks of different shape and size and for different ferritic materials (2 1/4% Cr - and 12% Cr-steel) were performed by TNO and by INTERATOM, using several sodium test facilities. Many fabrication-methods of artificial micro-leaks were applied and examined. Selfplugging-, selfwastage- and reopening-effects were observed and evaluated during different time periods and under various test conditions. The main results will be discussed. Concerning the leak propagation program of INTERATOM, the first series of experiments was carried out this year. A short status report and some first results will be given. (author)

VCSEL-based sensors for distance and velocity

Science.gov (United States)

Moench, Holger; Carpaij, Mark; Gerlach, Philipp; Gronenborn, Stephan; Gudde, Ralph; Hellmig, Jochen; Kolb, Johanna; van der Lee, Alexander

2016-03-01

VCSEL based sensors can measure distance and velocity in three dimensional space and are already produced in high quantities for professional and consumer applications. Several physical principles are used: VCSELs are applied as infrared illumination for surveillance cameras. High power arrays combined with imaging optics provide a uniform illumination of scenes up to a distance of several hundred meters. Time-of-flight methods use a pulsed VCSEL as light source, either with strong single pulses at low duty cycle or with pulse trains. Because of the sensitivity to background light and the strong decrease of the signal with distance several Watts of laser power are needed at a distance of up to 100m. VCSEL arrays enable power scaling and can provide very short pulses at higher power density. Applications range from extended functions in a smartphone over industrial sensors up to automotive LIDAR for driver assistance and autonomous driving. Self-mixing interference works with coherent laser photons scattered back into the cavity. It is therefore insensitive to environmental light. The method is used to measure target velocity and distance with very high accuracy at distances up to one meter. Single-mode VCSELs with integrated photodiode and grating stabilized polarization enable very compact and cost effective products. Besides the well know application as computer input device new applications with even higher accuracy or for speed over ground measurement in automobiles and up to 250km/h are investigated. All measurement methods exploit the known VCSEL properties like robustness, stability over temperature and the potential for packages with integrated optics and electronics. This makes VCSEL sensors ideally suited for new mass applications in consumer and automotive markets.

Propagation dynamics of super-Gaussian beams in fractional Schrödinger equation: from linear to nonlinear regimes.

Science.gov (United States)

Zhang, Lifu; Li, Chuxin; Zhong, Haizhe; Xu, Changwen; Lei, Dajun; Li, Ying; Fan, Dianyuan

2016-06-27

We have investigated the propagation dynamics of super-Gaussian optical beams in fractional Schrödinger equation. We have identified the difference between the propagation dynamics of super-Gaussian beams and that of Gaussian beams. We show that, the linear propagation dynamics of the super-Gaussian beams with order m > 1 undergo an initial compression phase before they split into two sub-beams. The sub-beams with saddle shape separate each other and their interval increases linearly with propagation distance. In the nonlinear regime, the super-Gaussian beams evolve to become a single soliton, breathing soliton or soliton pair depending on the order of super-Gaussian beams, nonlinearity, as well as the Lévy index. In two dimensions, the linear evolution of super-Gaussian beams is similar to that for one dimension case, but the initial compression of the input super-Gaussian beams and the diffraction of the splitting beams are much stronger than that for one dimension case. While the nonlinear propagation of the super-Gaussian beams becomes much more unstable compared with that for the case of one dimension. Our results show the nonlinear effects can be tuned by varying the Lévy index in the fractional Schrödinger equation for a fixed input power.

Proprioceptive body illusions modulate the visual perception of reaching distance.

Directory of Open Access Journals (Sweden)

Agustin Petroni

Full Text Available The neurobiology of reaching has been extensively studied in human and non-human primates. However, the mechanisms that allow a subject to decide-without engaging in explicit action-whether an object is reachable are not fully understood. Some studies conclude that decisions near the reach limit depend on motor simulations of the reaching movement. Others have shown that the body schema plays a role in explicit and implicit distance estimation, especially after motor practice with a tool. In this study we evaluate the causal role of multisensory body representations in the perception of reachable space. We reasoned that if body schema is used to estimate reach, an illusion of the finger size induced by proprioceptive stimulation should propagate to the perception of reaching distances. To test this hypothesis we induced a proprioceptive illusion of extension or shrinkage of the right index finger while participants judged a series of LEDs as reachable or non-reachable without actual movement. Our results show that reach distance estimation depends on the illusory perceived size of the finger: illusory elongation produced a shift of reaching distance away from the body whereas illusory shrinkage produced the opposite effect. Combining these results with previous findings, we suggest that deciding if a target is reachable requires an integration of body inputs in high order multisensory parietal areas that engage in movement simulations through connections with frontal premotor areas.

Low-Cost Ultrasonic Distance Sensor Arrays with Networked Error Correction

Directory of Open Access Journals (Sweden)

Tianzhou Chen

2013-09-01

Full Text Available Distance has been one of the basic factors in manufacturing and control fields, and ultrasonic distance sensors have been widely used as a low-cost measuring tool. However, the propagation of ultrasonic waves is greatly affected by environmental factors such as temperature, humidity and atmospheric pressure. In order to solve the problem of inaccurate measurement, which is significant within industry, this paper presents a novel ultrasonic distance sensor model using networked error correction (NEC trained on experimental data. This is more accurate than other existing approaches because it uses information from indirect association with neighboring sensors, which has not been considered before. The NEC technique, focusing on optimization of the relationship of the topological structure of sensor arrays, is implemented for the compensation of erroneous measurements caused by the environment. We apply the maximum likelihood method to determine the optimal fusion data set and use a neighbor discovery algorithm to identify neighbor nodes at the top speed. Furthermore, we adopt the NEC optimization algorithm, which takes full advantage of the correlation coefficients for neighbor sensors. The experimental results demonstrate that the ranging errors of the NEC system are within 2.20%; furthermore, the mean absolute percentage error is reduced to 0.01% after three iterations of this method, which means that the proposed method performs extremely well. The optimized method of distance measurement we propose, with the capability of NEC, would bring a significant advantage for intelligent industrial automation.

Transionospheric propagation predictions

Science.gov (United States)

Klobucher, J. A.; Basu, S.; Basu, S.; Bernhardt, P. A.; Davies, K.; Donatelli, D. E.; Fremouw, E. J.; Goodman, J. M.; Hartmann, G. K.; Leitinger, R.

1979-01-01

The current status and future prospects of the capability to make transionospheric propagation predictions are addressed, highlighting the effects of the ionized media, which dominate for frequencies below 1 to 3 GHz, depending upon the state of the ionosphere and the elevation angle through the Earth-space path. The primary concerns are the predictions of time delay of signal modulation (group path delay) and of radio wave scintillation. Progress in these areas is strongly tied to knowledge of variable structures in the ionosphere ranging from the large scale (thousands of kilometers in horizontal extent) to the fine scale (kilometer size). Ionospheric variability and the relative importance of various mechanisms responsible for the time histories observed in total electron content (TEC), proportional to signal group delay, and in irregularity formation are discussed in terms of capability to make both short and long term predictions. The data base upon which predictions are made is examined for its adequacy, and the prospects for prediction improvements by more theoretical studies as well as by increasing the available statistical data base are examined.

Probing Intrinsic Properties of Short Gamma-Ray Bursts with Gravitational Waves.

Science.gov (United States)

Fan, Xilong; Messenger, Christopher; Heng, Ik Siong

2017-11-03

Progenitors of short gamma-ray bursts are thought to be neutron stars coalescing with their companion black hole or neutron star, which are one of the main gravitational wave sources. We have devised a Bayesian framework for combining gamma-ray burst and gravitational wave information that allows us to probe short gamma-ray burst luminosities. We show that combined short gamma-ray burst and gravitational wave observations not only improve progenitor distance and inclination angle estimates, they also allow the isotropic luminosities of short gamma-ray bursts to be determined without the need for host galaxy or light-curve information. We characterize our approach by simulating 1000 joint short gamma-ray burst and gravitational wave detections by Advanced LIGO and Advanced Virgo. We show that ∼90% of the simulations have uncertainties on short gamma-ray burst isotropic luminosity estimates that are within a factor of two of the ideal scenario, where the distance is known exactly. Therefore, isotropic luminosities can be confidently determined for short gamma-ray bursts observed jointly with gravitational waves detected by Advanced LIGO and Advanced Virgo. Planned enhancements to Advanced LIGO will extend its range and likely produce several joint detections of short gamma-ray bursts and gravitational waves. Third-generation gravitational wave detectors will allow for isotropic luminosity estimates for the majority of the short gamma-ray burst population within a redshift of z∼1.

A 10-A spectroscopic ruler applied to short polyprolines.

Science.gov (United States)

Sahoo, Harekrushna; Roccatano, Danilo; Hennig, Andreas; Nau, Werner M

2007-08-08

Fluorescence resonance energy transfer (FRET) from the amino acid tryptophan (Trp) as donor and a 2,3-diazabicyclo[2.2.2]oct-2-ene-labeled asparagine (Dbo) as acceptor in peptides of the general structure Trp-(Pro)n-Dbo-NH2 (n = 1-6) was investigated by steady-state and time-resolved fluorescence, CD, and NMR spectroscopy as well as by molecular dynamics (MD) simulations (GROMOS96 force field). The Trp/Dbo FRET pair is characterized by a very short Förster radius (R0 ca. 9 A), which allowed distance determinations in such short peptides. Water and propylene glycol were investigated as solvents. The peptides were designed to show an early nucleation of the poly(Pro)II (PPII) secondary helix structure for n > or = 2, which was confirmed by their CD spectra. The shortest peptide (n = 1) adopts preferentially the trans conformation about the Trp-Pro bond, as confirmed by NMR spectra. The FRET efficiencies ranged 2-72% and were found to depend sensitively on the peptide length, i.e., the number of intervening proline residues. The analysis of the FRET data at different levels of theory (assuming either a fixed distance or distance distributions according to a wormlike chain or Gaussian model) afforded donor-acceptor distances between ca. 8 A (n = 1) and ca. 16 A (n = 6) in water, which were found to be similar or slightly higher in propylene glycol. The distances afforded by the Trp/Dbo FRET pair were found to be reasonable in comparison to literature data, expectations from the PPII helix structure, and the results from MD simulations. The persistence lengths for the longer peptides were found to lie at 30-70 A in water and 220 +/- 40 A in propylene glycol, suggesting a more rigid PPII helical structure in propylene glycol. A detailed comparison with literature data on FRET in polyprolines demonstrates that the donor-acceptor distances extracted by FRET are correlated with the Förster radii of the employed FRET pairs. This demonstrates the limitations of using FRET

Silicon carbide production by Self-Propagating High Temperature (SHS) technique

International Nuclear Information System (INIS)

Lima, Eduardo de Souza; Schneider, Pedro Luiz; Mattoso, Irani Guedes; Costa, Carlos Roberto Correia da; Louro, Luis Henrique Leme

1997-01-01

Samples of silicon carbide (SiC) were synthesized from a mixture of silicon and carbon powders, using the Self-Propagating High Temperature Synthesis (SHS) technique. Three mixtures were tried, using silicon particles of the same average size but carbon particles of different average sizes. The method tried is characterized by an ignition temperature of 1450 deg C and the short duration of the synthesis ( 2-3 min). The samples were characterized by X-ray diffraction and scattering electron microscopy. (author)

Soot Formation in Freely-Propagating Laminar Premixed Flames

Science.gov (United States)

Lin, K.-C.; Hassan, M. I.; Faeth, G. M.

1997-01-01

Soot formation within hydrocarbon-fueled flames is an important unresolved problem of combustion science. Thus, the present study is considering soot formation in freely-propagating laminar premixed flames, exploiting the microgravity environment to simplify measurements at the high-pressure conditions of interest for many practical applications. The findings of the investigation are relevant to reducing emissions of soot and continuum radiation from combustion processes, to improving terrestrial and spacecraft fire safety, and to developing methods of computational combustion, among others. Laminar premixed flames are attractive for studying soot formation because they are simple one-dimensional flows that are computationally tractable for detailed numerical simulations. Nevertheless, studying soot-containing burner-stabilized laminar premixed flames is problematical: spatial resolution and residence times are limited at the pressures of interest for practical applications, flame structure is sensitive to minor burner construction details so that experimental reproducibility is not very good, consistent burner behavior over the lengthy test programs needed to measure soot formation properties is hard to achieve, and burners have poor durability. Fortunately, many of these problems are mitigated for soot-containing, freely-propagating laminar premixed flames. The present investigation seeks to extend work in this laboratory for various soot processes in flames by observing soot formation in freely-propagating laminar premixed flames. Measurements are being made at both Normal Gravity (NG) and MicroGravity (MG), using a short-drop free-fall facility to provide MG conditions.

Development of a wind farm noise propagation prediction model - project progress to date

International Nuclear Information System (INIS)

Robinson, P.; Bullmore, A.; Bass, J.; Sloth, E.

1998-01-01

This paper describes a twelve month measurement campaign which is part of a European project (CEC Project JOR3-CT95-0051) with the aim to substantially reduce the uncertainties involved in predicting environmentally radiated noise levels from wind farms (1). This will be achieved by comparing noise levels measure at varying distances from single and multiple sources over differing complexities of terrain with those predicted using a number of currently adopted sound propagation models. Specific objectives within the project are to: establish the important parameters controlling the propagation of wind farm noise to the far field; develop a planning tool for predicting wind farm noise emission levels under practically encountered conditions; place confidence limits on the upper and lower bounds of the noise levels predicted, thus enabling developers to quantify the risk whether noise emission from wind farms will cause nuisance to nearby residents. (Author)

Spatiotemporal Propagation of the Cortical Atrophy: Population and Individual Patterns

Directory of Open Access Journals (Sweden)

Igor Koval

2018-05-01

Full Text Available Repeated failures in clinical trials for Alzheimer’s disease (AD have raised a strong interest for the prodromal phase of the disease. A better understanding of the brain alterations during this early phase is crucial to diagnose patients sooner, to estimate an accurate disease stage, and to give a reliable prognosis. According to recent evidence, structural alterations in the brain are likely to be sensitive markers of the disease progression. Neuronal loss translates in specific spatiotemporal patterns of cortical atrophy, starting in the enthorinal cortex and spreading over other cortical regions according to specific propagation pathways. We developed a digital model of the cortical atrophy in the left hemisphere from prodromal to diseased phases, which is built on the temporal alignment and combination of several short-term observation data to reconstruct the long-term history of the disease. The model not only provides a description of the spatiotemporal patterns of cortical atrophy at the group level but also shows the variability of these patterns at the individual level in terms of difference in propagation pathways, speed of propagation, and age at propagation onset. Longitudinal MRI datasets of patients with mild cognitive impairments who converted to AD are used to reconstruct the cortical atrophy propagation across all disease stages. Each observation is considered as a signal spatially distributed on a network, such as the cortical mesh, each cortex location being associated to a node. We consider how the temporal profile of the signal varies across the network nodes. We introduce a statistical mixed-effect model to describe the evolution of the cortex alterations. To ensure a spatiotemporal smooth propagation of the alterations, we introduce a constrain on the propagation signal in the model such that neighboring nodes have similar profiles of the signal changes. Our generative model enables the reconstruction of personalized

Dependability investigation of wireless short range embedded systems: hardware platform oriented approach

NARCIS (Netherlands)

Senouci, B.; Kerkhoff, Hans G.; Annema, Anne J.; Bentum, Marinus Jan

2015-01-01

A new direction in short-range wireless applications has appeared in the form of high-speed data communication devices for distances of hundreds meters. Behind these embedded applications, a complex heterogeneous architecture is built. Moreover, these short range communications are introduced into

Detecting the long-distance structure of the X(3872)

Energy Technology Data Exchange (ETDEWEB)

Guo, Feng-Kun [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Hidalgo-Duque, Carlos; Nieves, Juan [Centro Mixto CSIC-Universidad de Valencia, Institutos de Investigacion de Paterna, Instituto de Fisica Corpuscular (IFIC), Valencia (Spain); Ozpineci, Altug [Middle East Technical University, Department of Physics, Ankara (Turkey); Valderrama, Manuel Pavon [Universite Paris-Sud, IN2P3/CNRS, Institut de Physique Nucleaire, Orsay Cedex (France)

2014-05-15

We study the X(3872) → D{sup 0} anti D{sup 0}π{sup 0} decay within a D anti D* molecular picture for the X(3872) state. This decay mode is more sensitive to the long-distance structure of the X(3872) resonance than its J/ψππ and J/ψ3π decays, which are mainly controlled by the details of the X(3872) wave function at short distances. We show that the D{sup 0} anti D{sup 0} final state interaction can be important, and that a precise measurement of this partial decay width can provide valuable information on the interaction strength between the D{sup (*)} anti D{sup (*)} charm mesons. (orig.)

INTEGRATING INTERNET PROTOCOL TELEVISION (IPTV IN DISTANCE EDUCATION: A Constructivist Framework for Social Networking

Directory of Open Access Journals (Sweden)

T. Volkan YUZER

2011-07-01

Full Text Available New communication technologies and constructivist pedagogy have the great potential to build very powerful paradigm shifts that enhance Internet Protocol Television (IPTV in distance education. Therefore, the main purpose of this chapter is to explore the new concerns, issues and potentials for the IPTV delivery of distance education to multicultural populations. In this study, the design strategies and principles of how to build social networking based on constructivist learning theory are discussed in order to generate a theoretical framework that provides everyday examples and experiences for IPTV in distance education. This framework also shows the needs, expectations and beliefs, and strengths-weaknesses of IPTV in distance. In short, this framework concentrates on discussing the main characteristics of IPTV in distance education and describes how those characteristics can help build constructivist online communities.

DISCOVERY OF UBIQUITOUS FAST-PROPAGATING INTENSITY DISTURBANCES BY THE CHROMOSPHERIC LYMAN ALPHA SPECTROPOLARIMETER (CLASP)

Energy Technology Data Exchange (ETDEWEB)

Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando, T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G. [National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Tsuneta, S.; Ishikawa, S.; Shimizu, T.; Sakao, T. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Winebarger, A.; Kobayashi, K.; Cirtain, J. [NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812 (United States); Champey, P. [University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, AL 35899 (United States); Auchère, F. [Institut d’Astrophysique Spatiale, CNRS/Univ. Paris-Sud 11, Bâtiment 121, F-91405 Orsay (France); Bueno, J. Trujillo; Ramos, A. Asensio, E-mail: masahito.kubo@nao.ac.jp [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); and others

2016-12-01

High-cadence observations by the slit-jaw (SJ) optics system of the sounding rocket experiment known as the Chromospheric Lyman Alpha Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances that recurrently propagate in either the chromosphere or the transition region or both at a speed much higher than the speed of sound. The CLASP/SJ instrument provides a time series of two-dimensional images taken with broadband filters centered on the Ly α line at a 0.6 s cadence. The multiple fast-propagating intensity disturbances appear in the quiet Sun and in an active region, and they are clearly detected in at least 20 areas in a field of view of 527″ × 527″ during the 5 minute observing time. The apparent speeds of the intensity disturbances range from 150 to 350 km s{sup −1}, and they are comparable to the local Alfvén speed in the transition region. The intensity disturbances tend to propagate along bright elongated structures away from areas with strong photospheric magnetic fields. This suggests that the observed fast-propagating intensity disturbances are related to the magnetic canopy structures. The maximum distance traveled by the intensity disturbances is about 10″, and the widths are a few arcseconds, which are almost determined by a pixel size of 1.″03. The timescale of each intensity pulse is shorter than 30 s. One possible explanation for the fast-propagating intensity disturbances observed by CLASP is magnetohydrodynamic fast-mode waves.

Propagation and Interaction Properties of Successive Coronal Mass Ejections in Relation to a Complex Type II Radio Burst

Science.gov (United States)

Liu, Y. D.; Zhao, X.; Zhu, B.

2017-12-01

We examine the propagation and interaction properties of three successive coronal mass ejections (CMEs) from 2001 November 21-22, with a focus on their connection with the behaviors of the associated long-duration complex type II radio burst. In combination with coronagraph and multi-point in situ observations, the long-duration type II burst provides key features that help resolve the propagation and interaction complexities of the three CMEs. The two CMEs from November 22 interacted first and then overtook the November 21 CME at a distance of about 0.85 AU from the Sun. The time scale that the shock originally driven by the last CME spent inside the preceding two CMEs is estimated to be about 14 and 6 hr, respectively. We present a simple analytical model without any free parameters to characterize the whole Sun-to-Earth propagation of the shock, which shows a remarkable consistency with all the available data and MHD simulations even out to the distance of Ulysses (2.34 AU). The coordination of in situ measurements at the Earth and Ulysses, which were separated by 73o in latitude, gives important clues for the understanding of shock structure and the interpretation of in situ signatures. The results also indicate means to increase geo-effectiveness with three CMEs, similar to the the ``perfect storm" scenario proposed by te{liu14a} although the current case is not ``super" in the same sense as the 2012 July 23 event.

Experimental study of 112 Gb/s short reach transmission employing PAM formats and SiP intensity modulator at 1.3 μm.

Science.gov (United States)

Chagnon, Mathieu; Osman, Mohamed; Poulin, Michel; Latrasse, Christine; Gagné, Jean-Frédéric; Painchaud, Yves; Paquet, Carl; Lessard, Stéphane; Plant, David

2014-08-25

We present a Silicon Photonic (SiP) intensity modulator operating at 1.3 μm with pulse amplitude modulation formats for short reach transmission employing a digital to analog converter for the RF signal generator, enabling pulse shaping and precompensation of the transmitter's frequency response. Details of the SiP Mach-Zehnder interfometer are presented. We study the system performance at various bit rates, PAM orders and propagation distances. To the best of our knowledge, we report the first demonstration of a 112 Gb/s transmission over 10 km of SMF fiber operating below pre-FEC BER threshold of 3.8 × 10(-3) employing PAM-8 at 37.4 Gbaud using a fully packaged SiP modulator. An analytical model for the Q-factor metric applicable for multilevel PAM-N signaling is derived and accurately experimentally verified in the case of Gaussian noise limited detection. System performance is experimentally investigated and it is demonstrated that PAM order selection can be optimally chosen as a function of the desired throughput. We demonstrate the ability of the proposed transmitter to exhibit software-defined transmission for short reach applications by selecting PAM order, symbol rate and pulse shape.

Quantum Dynamics with Short-Time Trajectories and Minimal Adaptive Basis Sets.

Science.gov (United States)

Saller, Maximilian A C; Habershon, Scott

2017-07-11

Methods for solving the time-dependent Schrödinger equation via basis set expansion of the wave function can generally be categorized as having either static (time-independent) or dynamic (time-dependent) basis functions. We have recently introduced an alternative simulation approach which represents a middle road between these two extremes, employing dynamic (classical-like) trajectories to create a static basis set of Gaussian wavepackets in regions of phase-space relevant to future propagation of the wave function [J. Chem. Theory Comput., 11, 8 (2015)]. Here, we propose and test a modification of our methodology which aims to reduce the size of basis sets generated in our original scheme. In particular, we employ short-time classical trajectories to continuously generate new basis functions for short-time quantum propagation of the wave function; to avoid the continued growth of the basis set describing the time-dependent wave function, we employ Matching Pursuit to periodically minimize the number of basis functions required to accurately describe the wave function. Overall, this approach generates a basis set which is adapted to evolution of the wave function while also being as small as possible. In applications to challenging benchmark problems, namely a 4-dimensional model of photoexcited pyrazine and three different double-well tunnelling problems, we find that our new scheme enables accurate wave function propagation with basis sets which are around an order-of-magnitude smaller than our original trajectory-guided basis set methodology, highlighting the benefits of adaptive strategies for wave function propagation.

High intensity pulse self-compression in short hollow core capillaries

OpenAIRE

Butcher, Thomas J.; Anderson, Patrick N.; Horak, Peter; Frey, Jeremy G.; Brocklesby, William S.

2011-01-01

The drive for shorter pulses for use in techniques such as high harmonic generation and laser wakefield acceleration requires continual improvement in post-laser pulse compression techniques. The two most commonly used methods of pulse compression for high intensity pulses are hollow capillary compression via self-phase modulation (SPM) [1] and the more recently developed filamentation [2]. Both of these methods can require propagation distances of 1-3 m to achieve spectral broadening and com...

Wave propagation in elastic solids

CERN Document Server

Achenbach, Jan

1984-01-01

The propagation of mechanical disturbances in solids is of interest in many branches of the physical scienses and engineering. This book aims to present an account of the theory of wave propagation in elastic solids. The material is arranged to present an exposition of the basic concepts of mechanical wave propagation within a one-dimensional setting and a discussion of formal aspects of elastodynamic theory in three dimensions, followed by chapters expounding on typical wave propagation phenomena, such as radiation, reflection, refraction, propagation in waveguides, and diffraction. The treat

Nonlinear elastic longitudinal strain-wave propagation in a plate with nonequilibrium laser-generated point defects

International Nuclear Information System (INIS)

Mirzade, Fikret Kh.

2005-01-01

The propagation of longitudinal strain wave in a plate with quadratic nonlinearity of elastic continuum was studied in the context of a model that takes into account the joint dynamics of elastic displacements in the medium and the concentration of the nonequilibrium laser-induced point defects. The input equations of the problem are reformulated in terms of only the total displacements of the medium points. In this case, the presence of structural defects manifests itself in the emergence of a delayed response of the system to the propagation of the strain-related perturbations, which is characteristic of media with relaxation or memory. The model equations describing the nonlinear displacement wave were derived with allowance made for the values of the relaxation parameter. The influence of the generation and relaxation of lattice defects on the propagation of this wave was analyzed. It is shown that, for short relaxation times of defects, the strain can propagate in the form of shock fronts. In the case of longer relaxation times, shock waves do not form and the strain wave propagates only in the form of solitary waves or a train of solitons. The contributions of the finiteness of the defect-recombination rate to linear and nonlinear elastic modulus, and spatial dispersion are determined

Visible propagation from invisible exogenous cueing.

Science.gov (United States)

Lin, Zhicheng; Murray, Scott O

2013-09-20

Perception and performance is affected not just by what we see but also by what we do not see-inputs that escape our awareness. While conscious processing and unconscious processing have been assumed to be separate and independent, here we report the propagation of unconscious exogenous cueing as determined by conscious motion perception. In a paradigm combining masked exogenous cueing and apparent motion, we show that, when an onset cue was rendered invisible, the unconscious exogenous cueing effect traveled, manifesting at uncued locations (4° apart) in accordance with conscious perception of visual motion; the effect diminished when the cue-to-target distance was 8° apart. In contrast, conscious exogenous cueing manifested in both distances. Further evidence reveals that the unconscious and conscious nonretinotopic effects could not be explained by an attentional gradient, nor by bottom-up, energy-based motion mechanisms, but rather they were subserved by top-down, tracking-based motion mechanisms. We thus term these effects mobile cueing. Taken together, unconscious mobile cueing effects (a) demonstrate a previously unknown degree of flexibility of unconscious exogenous attention; (b) embody a simultaneous dissociation and association of attention and consciousness, in which exogenous attention can occur without cue awareness ("dissociation"), yet at the same time its effect is contingent on conscious motion tracking ("association"); and (c) underscore the interaction of conscious and unconscious processing, providing evidence for an unconscious effect that is not automatic but controlled.

UWB pulse propagation into human tissues

International Nuclear Information System (INIS)

Cavagnaro, Marta; Pittella, Erika; Pisa, Stefano

2013-01-01

In this paper the propagation of a UWB pulse into a layered model of the human body is studied to characterize absorption and reflection of the UWB signal due to the different body tissues. Several time behaviours for the incident UWB pulse are considered and compared with reference to the feasibility of breath and heartbeat activity monitoring. Results show that if the UWB source is placed far from the human body, the reflection coming from the interface between air and skin can be used to detect the respiratory activity. On the contrary, if the UWB source is placed close to the human body, a small reflection due to the interface between the posterior lung wall and the bone, which is well distanced in time from the reflections due to the first layers of the body model, can be used to detect lung and heart changes associated with the cardio-respiratory activity. (paper)

Quasilinear dynamics of a cloud of hot electrons propagating through a plasma with decreasing density and temperature

International Nuclear Information System (INIS)

Foroutan, G.; Khalilpour, H.; Moslehi-Fard, M.; Li, B.; Robinson, P. A.

2008-01-01

The effects of plasma inhomogeneities on the propagation of a cloud of hot electrons through a cold background plasma and generation of Langmuir waves are investigated using numerical simulations of the quasilinear equations. It is found that in a plasma with decreasing density the quasilinear relaxation of the electron distribution in velocity space is accelerated and the levels of the generated Langmuir waves are enhanced. The magnitude of the induced emission rate is increased and its maximum value moves to lower velocities. Due to density gradient the height of plateau shows an increase at small distances and a corresponding decrease at large distances. It is also found that in a plasma with decreasing temperature, the relaxation of the beam is retarded, the spectral density of Langmuir waves is broadened, and the height of the plateau decreases below its value in a uniform plasma. In the presence of both density and temperature gradients, at given position, the height and upper boundary of the plateau and the level of Langmuir waves are all increased at small velocities. The spatial expansion of the beam is increased by the plasma inhomogeneities, but its average velocity of propagation decreases. Initially, at a given position, the velocity at the upper boundary of the plateau is smaller in the presence of the density gradient than in the uniform plasma but the reverse is true at longer times. Due to temperature gradient, at large times and small distances, the upper boundary of the plateau is increased above its value in the uniform plasma. Because of fast relaxation, the value of the lower boundary of the plateau in the plasma with decreasing density is always less than its value in the uniform plasma. It is found that the local velocity of the beam decreases when the density gradient is present. The local velocity spread of the beam remains unchanged during the propagation of the beam in the uniform plasma, but increases in the presence of inhomogeneities.

Database for propagation models

Science.gov (United States)

Kantak, Anil V.

1991-07-01

A propagation researcher or a systems engineer who intends to use the results of a propagation experiment is generally faced with various database tasks such as the selection of the computer software, the hardware, and the writing of the programs to pass the data through the models of interest. This task is repeated every time a new experiment is conducted or the same experiment is carried out at a different location generating different data. Thus the users of this data have to spend a considerable portion of their time learning how to implement the computer hardware and the software towards the desired end. This situation may be facilitated considerably if an easily accessible propagation database is created that has all the accepted (standardized) propagation phenomena models approved by the propagation research community. Also, the handling of data will become easier for the user. Such a database construction can only stimulate the growth of the propagation research it if is available to all the researchers, so that the results of the experiment conducted by one researcher can be examined independently by another, without different hardware and software being used. The database may be made flexible so that the researchers need not be confined only to the contents of the database. Another way in which the database may help the researchers is by the fact that they will not have to document the software and hardware tools used in their research since the propagation research community will know the database already. The following sections show a possible database construction, as well as properties of the database for the propagation research.

An adaptive distance measure for use with nonparametric models

International Nuclear Information System (INIS)

Garvey, D. R.; Hines, J. W.

2006-01-01

Distance measures perform a critical task in nonparametric, locally weighted regression. Locally weighted regression (LWR) models are a form of 'lazy learning' which construct a local model 'on the fly' by comparing a query vector to historical, exemplar vectors according to a three step process. First, the distance of the query vector to each of the exemplar vectors is calculated. Next, these distances are passed to a kernel function, which converts the distances to similarities or weights. Finally, the model output or response is calculated by performing locally weighted polynomial regression. To date, traditional distance measures, such as the Euclidean, weighted Euclidean, and L1-norm have been used as the first step in the prediction process. Since these measures do not take into consideration sensor failures and drift, they are inherently ill-suited for application to 'real world' systems. This paper describes one such LWR model, namely auto associative kernel regression (AAKR), and describes a new, Adaptive Euclidean distance measure that can be used to dynamically compensate for faulty sensor inputs. In this new distance measure, the query observations that lie outside of the training range (i.e. outside the minimum and maximum input exemplars) are dropped from the distance calculation. This allows for the distance calculation to be robust to sensor drifts and failures, in addition to providing a method for managing inputs that exceed the training range. In this paper, AAKR models using the standard and Adaptive Euclidean distance are developed and compared for the pressure system of an operating nuclear power plant. It is shown that using the standard Euclidean distance for data with failed inputs, significant errors in the AAKR predictions can result. By using the Adaptive Euclidean distance it is shown that high fidelity predictions are possible, in spite of the input failure. In fact, it is shown that with the Adaptive Euclidean distance prediction

Stereotypical reaching movements of the octopus involve both bend propagation and arm elongation.

Science.gov (United States)

Hanassy, S; Botvinnik, A; Flash, T; Hochner, B

2015-05-13

The bend propagation involved in the stereotypical reaching movement of the octopus arm has been extensively studied. While these studies have analyzed the kinematics of bend propagation along the arm during its extension, possible length changes have been ignored. Here, the elongation profiles of the reaching movements of Octopus vulgaris were assessed using three-dimensional reconstructions. The analysis revealed that, in addition to bend propagation, arm extension movements involve elongation of the proximal part of the arm, i.e., the section from the base of the arm to the propagating bend. The elongations are quite substantial and highly variable, ranging from an average strain along the arm of -0.12 (i.e. shortening) up to 1.8 at the end of the movement (0.57 ± 0.41, n = 64 movements, four animals). Less variability was discovered in an additional set of experiments on reaching movements (0.64 ± 0.28, n = 30 movements, two animals), where target and octopus positions were kept more stationary. Visual observation and subsequent kinematic analysis suggest that the reaching movements can be broadly segregated into two groups. The first group involves bend propagation beginning at the base of the arm and propagating towards the arm tip. In the second, the bend is formed or present more distally and reaching is achieved mainly by elongation and straightening of the segment proximal to the bend. Only in the second type of movements is elongation significantly positively correlated with the distance of the bend from the target. We suggest that reaching towards a target is generated by a combination of both propagation of a bend along the arm and arm elongation. These two motor primitives may be combined to create a broad spectrum of reaching movements. The dynamical model, which recapitulates the biomechanics of the octopus muscular hydrostatic arm, suggests that achieving the observed elongation requires an extremely low ratio of longitudinal to transverse muscle

Atmospheric-radiation boundary conditions for high-frequency waves in time-distance helioseismology

Science.gov (United States)

Fournier, D.; Leguèbe, M.; Hanson, C. S.; Gizon, L.; Barucq, H.; Chabassier, J.; Duruflé, M.

2017-12-01

The temporal covariance between seismic waves measured at two locations on the solar surface is the fundamental observable in time-distance helioseismology. Above the acoustic cut-off frequency ( 5.3 mHz), waves are not trapped in the solar interior and the covariance function can be used to probe the upper atmosphere. We wish to implement appropriate radiative boundary conditions for computing the propagation of high-frequency waves in the solar atmosphere. We consider recently developed and published radiative boundary conditions for atmospheres in which sound-speed is constant and density decreases exponentially with radius. We compute the cross-covariance function using a finite element method in spherical geometry and in the frequency domain. The ratio between first- and second-skip amplitudes in the time-distance diagram is used as a diagnostic to compare boundary conditions and to compare with observations. We find that a boundary condition applied 500 km above the photosphere and derived under the approximation of small angles of incidence accurately reproduces the "infinite atmosphere" solution for high-frequency waves. When the radiative boundary condition is applied 2 Mm above the photosphere, we find that the choice of atmospheric model affects the time-distance diagram. In particular, the time-distance diagram exhibits double-ridge structure when using a Vernazza Avrett Loeser atmospheric model.

Propagating intensity disturbances in polar corona as seen from AIA/SDO

Science.gov (United States)

Krishna Prasad, S.; Banerjee, D.; Gupta, G. R.

2011-04-01

Context. Polar corona is often explored to find the energy source for the acceleration of the fast solar wind. Earlier observations show omni-presence of quasi-periodic disturbances, traveling outward, which is believed to be caused by the ubiquitous presence of outward propagating waves. These waves, mostly of compressional type, might provide the additional momentum and heat required for the fast solar wind acceleration. It has been conjectured that these disturbances are not due to waves but high speed plasma outflows, which are difficult to distinguish using the current available techniques. Aims: With the unprecedented high spatial and temporal resolution of AIA/SDO, we search for these quasi-periodic disturbances in both plume and interplume regions of the polar corona. We investigate their nature of propagation and search for a plausible interpretation. We also aim to study their multi-thermal nature by using three different coronal passbands of AIA. Methods: We chose several clean plume and interplume structures and studied the time evolution of specific channels by making artificial slits along them. Taking the average across the slits, space-time maps are constructed and then filtration techniques are applied to amplify the low-amplitude oscillations. To suppress the effect of fainter jets, we chose wider slits than usual. Results: In almost all the locations chosen, in both plume and interplume regions we find the presence of propagating quasi-periodic disturbances, of periodicities ranging from 10-30 min. These are clearly seen in two channels and in a few cases out to very large distances (≈250″) off-limb, almost to the edge of the AIA field of view. The propagation speeds are in the range of 100-170 km s-1. The average speeds are different for different passbands and higher in interplume regions. Conclusions: Propagating disturbances are observed, even after removing the effects of jets and are insensitive to changes in slit width. This indicates

PERBANDINGAN EUCLIDEAN DISTANCE DENGAN CANBERRA DISTANCE PADA FACE RECOGNITION

Directory of Open Access Journals (Sweden)

Sendhy Rachmat Wurdianarto

2014-08-01

Full Text Available Perkembangan ilmu pada dunia komputer sangatlah pesat. Salah satu yang menandai hal ini adalah ilmu komputer telah merambah pada dunia biometrik. Arti biometrik sendiri adalah karakter-karakter manusia yang dapat digunakan untuk membedakan antara orang yang satu dengan yang lainnya. Salah satu pemanfaatan karakter / organ tubuh pada setiap manusia yang digunakan untuk identifikasi (pengenalan adalah dengan memanfaatkan wajah. Dari permasalahan diatas dalam pengenalan lebih tentang aplikasi Matlab pada Face Recognation menggunakan metode Euclidean Distance dan Canberra Distance. Model pengembangan aplikasi yang digunakan adalah model waterfall. Model waterfall beriisi rangkaian aktivitas proses yang disajikan dalam proses analisa kebutuhan, desain menggunakan UML (Unified Modeling Language, inputan objek gambar diproses menggunakan Euclidean Distance dan Canberra Distance. Kesimpulan yang dapat ditarik adalah aplikasi face Recognation menggunakan metode euclidean Distance dan Canverra Distance terdapat kelebihan dan kekurangan masing-masing. Untuk kedepannya aplikasi tersebut dapat dikembangkan dengan menggunakan objek berupa video ataupun objek lainnya.   Kata kunci : Euclidean Distance, Face Recognition, Biometrik, Canberra Distance

Is transport distance correlated with animal welfare and carcass quality of reindeer (Rangifer tarandus tarandus)?

Science.gov (United States)

Laaksonen, Sauli; Jokelainen, Pikka; Pusenius, Jyrki; Oksanen, Antti

2017-03-15

Slaughter reindeer are exposed to stress caused by gathering, handling, loading and unloading, and by conditions in vehicles during transport. These stress factors can lead to compromised welfare and trauma such as bruises or fractures, aspiration of rumen content, and abnormal odour in carcasses, and causing condemnations in meat inspection and lower meat quality. We investigated the statistical association of slaughter transport distance with these indices using meat inspection data from years 2004-2016, including inspection of 669,738 reindeer originating from Finnish reindeer herding areas. Increased stress and decreased welfare of reindeer, as indicated by higher incidence of carcass condemnation due to bruises or fractures, aspiration of rumen content, or abnormal odour, were positively associated with systems involving shorter transport distances to abattoirs. Significant differences in incidence of condemnations were also detected between abattoirs and reindeer herding cooperatives. This study indicates that in particular the short-distance transports of reindeer merit more attention. While the results suggest that factors associated with long distance transport, such as driver education, truck design, veterinary supervision, and specialist equipment, may be favourable to reducing pre-slaughter stress in reindeer when compared with short distance transport systems, which occur in a variety of vehicle types and may be done by untrained handlers. Further work is required to elucidate the causal factors to the current results.

Distance protection of multiple-circuit shared tower transmission lines with different voltages

DEFF Research Database (Denmark)

Silva, Filipe Miguel Faria da; Bak, Claus Leth

2017-01-01

Multiple-circuit transmission lines combining different voltage levels in one tower present extra challenges when setting a protection philosophy, as faults between voltage levels are possible. This study presents a detailed theoretical analysis of such combined faults, including the development...... of a formula for estimating the magnitude of the short-circuit current. It is demonstrated that if the faulted phase from the higher voltage level leads the faulted phase from the lower voltage level, a distance relay at the higher voltage level sees the fault in the forward direction, whereas a distance relay...

Propagation Properties of Airy Beam through Periodic Slab System with Negative Index Materials

Directory of Open Access Journals (Sweden)

Long Jin

2018-01-01

Full Text Available Based on light transfer matrix and electric field vector equation, the evolution of Airy beam propagating in periodic slab system with three negative index materials (NIMs and its transmission mechanism are investigated. The intensity profiles on emergent surface of periodic slab system and side view of Airy beam propagating in each right handed material (RHM and double negative material (DNM unit including lossless and losses DNMs are discussed. It is revealed that the self-recovery Airy beam can be achieved in long distance by using lossless periodic slab system as long as the negative refractive index nl=-nr and each unit length L=Z. As to losses slab system contained DNMs, the smaller the collision frequencies are, the better the Airy beam quality is formed. It is expected that the proposed manner of beam transmission and corresponding conclusions can be useful for extension applications of optical control, especially for optical communication and optical encryption technique.

Propagation of seasonal temperature signals into an aquifer upon bank infiltration.

Science.gov (United States)

Molina-Giraldo, Nelson; Bayer, Peter; Blum, Philipp; Cirpka, Olaf A

2011-01-01

Infiltrating river water carries the temperature signal of the river into the adjacent aquifer. While the diurnal temperature fluctuations are strongly dampened, the seasonal fluctuations are much less attenuated and can be followed into the aquifer over longer distances. In one-dimensional model with uniform properties, this signal is propagated with a retarded velocity, and its amplitude decreases exponentially with distance. Therefore, time shifts in seasonal temperature signals between rivers and groundwater observation points may be used to estimate infiltration rates and near-river groundwater velocities. As demonstrated in this study, however, the interpretation is nonunique under realistic conditions. We analyze a synthetic test case of a two-dimensional cross section perpendicular to a losing stream, accounting for multi-dimensional flow due to a partially penetrating channel, convective-conductive heat transport within the aquifer, and heat exchange with the underlying aquitard and the land surface. We compare different conceptual simplifications of the domain in order to elaborate on the importance of different system elements. We find that temperature propagation within the shallow aquifer can be highly influenced by conduction through the unsaturated zone and into the underlying aquitard. In contrast, regional groundwater recharge has no major effect on the simulated results. In our setup, multi-dimensionality of the flow field is important only close to the river. We conclude that over-simplistic analytical models can introduce substantial errors if vertical heat exchange at the aquifer boundaries is not accounted for. This has to be considered when using seasonal temperature fluctuations as a natural tracer for bank infiltration. Copyright © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association.

Room Volume Estimation Based on Ambiguity of Short-Term Interaural Phase Differences Using Humanoid Robot Head

Directory of Open Access Journals (Sweden)

Ryuichi Shimoyama

2016-07-01

Full Text Available Humans can recognize approximate room size using only binaural audition. However, sound reverberation is not negligible in most environments. The reverberation causes temporal fluctuations in the short-term interaural phase differences (IPDs of sound pressure. This study proposes a novel method for a binaural humanoid robot head to estimate room volume. The method is based on the statistical properties of the short-term IPDs of sound pressure. The humanoid robot turns its head toward a sound source, recognizes the sound source, and then estimates the ego-centric distance by its stereovision. By interpolating the relations between room volume, average standard deviation, and ego-centric distance experimentally obtained for various rooms in a prepared database, the room volume was estimated by the binaural audition of the robot from the average standard deviation of the short-term IPDs at the estimated distance.

The extra mile: Ungulate migration distance alters the use of seasonal range and exposure to anthropogenic risk

Science.gov (United States)

Sawyer, Hall; Middleton, Arthur D.; Hayes, Matthew M.; Kauffman, Matthew J.; Monteith, Kevin L.

2016-01-01

Partial migration occurs across a variety of taxa and has important ecological and evolutionary consequences. Among ungulates, studies of partially migratory populations have allowed researchers to compare and contrast performance metrics of migrants versus residents and examine how environmental factors influence the relative abundance of each. Such studies tend to characterize animals discretely as either migratory or resident, but we suggest that variable migration distances within migratory herds are an important and overlooked form of population structure, with potential consequences for animal fitness. We examined whether the variation in individual migration distances (20–264 km) within a single wintering population of mule deer (Odocoileus hemionus) was associated with several critical behavioral attributes of migration, including timing of migration, time allocation to seasonal ranges, and exposure to anthropogenic mortality risks. Both the timing of migration and the amount of time animals allocated to seasonal ranges varied with migration distance. Animals migrating long distances (150–250 km) initiated spring migration more than three weeks before than those migrating moderate (50–150 km) or short distances (forage and effectively increase carrying capacity. Clear differences in winter residency, migration duration, and risk of anthropogenic mortality among short-, moderate-, and long-distance migrants suggest fitness trade-offs may exist among migratory segments of the population. Future studies of partial migration may benefit from expanding comparisons of residents and migrants, to consider how variable migration distances of migrants may influence the costs and benefits of migration.

Monocular distance estimation from optic flow during active landing maneuvers

International Nuclear Information System (INIS)

Van Breugel, Floris; Morgansen, Kristi; Dickinson, Michael H

2014-01-01

Vision is arguably the most widely used sensor for position and velocity estimation in animals, and it is increasingly used in robotic systems as well. Many animals use stereopsis and object recognition in order to make a true estimate of distance. For a tiny insect such as a fruit fly or honeybee, however, these methods fall short. Instead, an insect must rely on calculations of optic flow, which can provide a measure of the ratio of velocity to distance, but not either parameter independently. Nevertheless, flies and other insects are adept at landing on a variety of substrates, a behavior that inherently requires some form of distance estimation in order to trigger distance-appropriate motor actions such as deceleration or leg extension. Previous studies have shown that these behaviors are indeed under visual control, raising the question: how does an insect estimate distance solely using optic flow? In this paper we use a nonlinear control theoretic approach to propose a solution for this problem. Our algorithm takes advantage of visually controlled landing trajectories that have been observed in flies and honeybees. Finally, we implement our algorithm, which we term dynamic peering, using a camera mounted to a linear stage to demonstrate its real-world feasibility. (paper)

Practical method of calculating time-integrated concentrations at medium and large distances

International Nuclear Information System (INIS)

Cagnetti, P.; Ferrara, V.

1980-01-01

Previous reports have covered the possibility of calculating time-integrated concentrations (TICs) for a prolonged release, based on concentration estimates for a brief release. This study proposes a simple method of evaluating concentrations in the air at medium and large distances, for a brief release. It is known that the stability of the atmospheric layers close to ground level influence diffusion only over short distances. Beyond some tens of kilometers, as the pollutant cloud progressively reaches higher layers, diffusion is affected by factors other than the stability at ground level, such as wind shear for intermediate distances and the divergence and rotational motion of air masses towards the upper limit of the mesoscale and on the synoptic scale. Using the data available in the literature, expressions for sigmasub(y) and sigmasub(z) are proposed for transfer times corresponding to those for up to distances of several thousand kilometres, for two initial diffusion situations (up to distances of 10 - 20 km), those characterized by stable and neutral conditions respectively. Using this method simple hand calculations can be made for any problem relating to the diffusion of radioactive pollutants over long distances

Short torch design for direct liquid sample introduction using conventional and micro-nebulizers for plasma spectrometry

Science.gov (United States)

Montaser, Akbar [Potomac, MD; Westphal, Craig S [Landenberg, PA; Kahen, Kaveh [Montgomery Village, MD; Rutkowski, William F [Arlington, VA

2008-01-08

An apparatus and method for providing direct liquid sample introduction using a nebulizer are provided. The apparatus and method include a short torch having an inner tube and an outer tube, and an elongated adapter having a cavity for receiving the nebulizer and positioning a nozzle tip of the nebulizer a predetermined distance from a tip of the outer tube of the short torch. The predetermined distance is preferably about 2-5 mm.

Encyclopedia of distances

CERN Document Server

Deza, Michel Marie

2016-01-01

This 4th edition of the leading reference volume on distance metrics is characterized by updated and rewritten sections on some items suggested by experts and readers, as well a general streamlining of content and the addition of essential new topics. Though the structure remains unchanged, the new edition also explores recent advances in the use of distances and metrics for e.g. generalized distances, probability theory, graph theory, coding theory, data analysis. New topics in the purely mathematical sections include e.g. the Vitanyi multiset-metric, algebraic point-conic distance, triangular ratio metric, Rossi-Hamming metric, Taneja distance, spectral semimetric between graphs, channel metrization, and Maryland bridge distance. The multidisciplinary sections have also been supplemented with new topics, including: dynamic time wrapping distance, memory distance, allometry, atmospheric depth, elliptic orbit distance, VLBI distance measurements, the astronomical system of units, and walkability distance. Lea...

Distance Learning

National Research Council Canada - National Science Library

Braddock, Joseph

1997-01-01

A study reviewing the existing Army Distance Learning Plan (ADLP) and current Distance Learning practices, with a focus on the Army's training and educational challenges and the benefits of applying Distance Learning techniques...

Long-distance signaling within Coleus x hybridus leaves; mediated by changes in intra-leaf CO2?

Science.gov (United States)

Stahlberg, R.; Van Volkenburgh, E.; Cleland, R. E.

2001-01-01

Rapid long-distance signaling in plants can occur via several mechanisms, including symplastic electric coupling and pressure waves. We show here in variegated Coleus leaves a rapid propagation of electrical signals that appears to be caused by changes in intra-leaf CO2 concentrations. Green leaf cells, when illuminated, undergo a rapid depolarization of their membrane potential (Vm) and an increase in their apoplastic pH (pHa) by a process that requires photosynthesis. This is followed by a slower hyperpolarization of Vm and apoplastic acidification, which do not require photosynthesis. White (chlorophyll-lacking) leaf cells, when in isolated white leaf segments, show only the slow response, but when in mixed (i.e. green and white) segments, the rapid Vm depolarization and increase in pHa propagate over more than 10 mm from the green to the white cells. Similarly, these responses propagate 12-20 mm from illuminated to unilluminated green cells. The fact that the propagation of these responses is eliminated when the leaf air spaces are infiltrated with solution indicates that the signal moves in the apoplast rather than the symplast. A depolarization of the mesophyll cells is induced in the dark by a decrease in apoplastic CO2 but not by an increase in pHa. These results support the hypothesis that the propagating signal for the depolarization of the white mesophyll cells is a photosynthetically induced decrease in the CO2 level of the air spaces throughout the leaf.

Signature of short distance physics on inflation power spectrum and CMB anisotropy

International Nuclear Information System (INIS)

Das, Suratna; Mohanty, Subhendra

2009-01-01

The inflaton field responsible for inflation may not be a canonical fundamental scalar. It is possible that the inflaton is a composite of fermions or it may have a decay width. In these cases the standard procedure for calculating the power spectrum is not applicable and a new formalism needs to be developed to determine the effect of short range interactions of the inflaton on the power spectrum and the CMB anisotropy. We develop a general formalism for computing the power spectrum of curvature perturbations for such non-canonical cases by using the flat space Källén-Lehmann spectral function in curved quasi-de Sitter space assuming implicitly that the Bunch-Davis boundary conditions enforces the inflaton mode functions to be plane wave in the short wavelength limit and a complete set of mode functions exists in quasi-de Sitter space. It is observed that the inflaton with a decay width suppresses the power at large scale while a composite inflaton's power spectrum oscillates at large scales. These observations may be vindicated in the WMAP data and confirmed by future observations with PLANCK

Epidemic spreading model to characterize misfolded proteins propagation in aging and associated neurodegenerative disorders.

Science.gov (United States)

Iturria-Medina, Yasser; Sotero, Roberto C; Toussaint, Paule J; Evans, Alan C

2014-11-01

Misfolded proteins (MP) are a key component in aging and associated neurodegenerative disorders. For example, misfolded Amyloid-ß (Aß) and tau proteins are two neuropathogenic hallmarks of Alzheimer's disease. Mechanisms underlying intra-brain MP propagation/deposition remain essentially uncharacterized. Here, is introduced an epidemic spreading model (ESM) for MP dynamics that considers propagation-like interactions between MP agents and the brain's clearance response across the structural connectome. The ESM reproduces advanced Aß deposition patterns in the human brain (explaining 46∼56% of the variance in regional Aß loads, in 733 subjects from the ADNI database). Furthermore, this model strongly supports a) the leading role of Aß clearance deficiency and early Aß onset age during Alzheimer's disease progression, b) that effective anatomical distance from Aß outbreak region explains regional Aß arrival time and Aß deposition likelihood, c) the multi-factorial impact of APOE e4 genotype, gender and educational level on lifetime intra-brain Aß propagation, and d) the modulatory impact of Aß propagation history on tau proteins concentrations, supporting the hypothesis of an interrelated pathway between Aß pathophysiology and tauopathy. To our knowledge, the ESM is the first computational model highlighting the direct link between structural brain networks, production/clearance of pathogenic proteins and associated intercellular transfer mechanisms, individual genetic/demographic properties and clinical states in health and disease. In sum, the proposed ESM constitutes a promising framework to clarify intra-brain region to region transference mechanisms associated with aging and neurodegenerative disorders.

Epidemic spreading model to characterize misfolded proteins propagation in aging and associated neurodegenerative disorders.

Directory of Open Access Journals (Sweden)

Yasser Iturria-Medina

2014-11-01

Full Text Available Misfolded proteins (MP are a key component in aging and associated neurodegenerative disorders. For example, misfolded Amyloid-ß (Aß and tau proteins are two neuropathogenic hallmarks of Alzheimer's disease. Mechanisms underlying intra-brain MP propagation/deposition remain essentially uncharacterized. Here, is introduced an epidemic spreading model (ESM for MP dynamics that considers propagation-like interactions between MP agents and the brain's clearance response across the structural connectome. The ESM reproduces advanced Aß deposition patterns in the human brain (explaining 46∼56% of the variance in regional Aß loads, in 733 subjects from the ADNI database. Furthermore, this model strongly supports a the leading role of Aß clearance deficiency and early Aß onset age during Alzheimer's disease progression, b that effective anatomical distance from Aß outbreak region explains regional Aß arrival time and Aß deposition likelihood, c the multi-factorial impact of APOE e4 genotype, gender and educational level on lifetime intra-brain Aß propagation, and d the modulatory impact of Aß propagation history on tau proteins concentrations, supporting the hypothesis of an interrelated pathway between Aß pathophysiology and tauopathy. To our knowledge, the ESM is the first computational model highlighting the direct link between structural brain networks, production/clearance of pathogenic proteins and associated intercellular transfer mechanisms, individual genetic/demographic properties and clinical states in health and disease. In sum, the proposed ESM constitutes a promising framework to clarify intra-brain region to region transference mechanisms associated with aging and neurodegenerative disorders.

Experience in nuclear engineering distance education at the University of Tennessee

International Nuclear Information System (INIS)

Dodds, H.L.

2011-01-01

This paper describes the distance education programs in nuclear engineering at The University of Tennessee (UT), which includes several courses that are of interest to the mathematics and computation community such as reactor theory and design, shielding, statistics, health physics, and criticality safety. All of the courses needed for the MS degree in nuclear engineering and several of the courses needed for the PhD degree in nuclear engineering are delivered synchronously (i.e., interactive in real time) via the Internet to students located anywhere by instructors located anywhere. The paper will also describe the historical development of distance education programs at UT as well as the benefits of the programs to students and to the university. The oral presentation associated with this paper will include a short movie that demonstrates the technology used for distance delivery. (author)

Dependency distance distribution - from the perspective of genre variation. Comment on "Dependency distance: a new perspective on syntactic patterns in natural languages" by Haitao Liu et al.

Science.gov (United States)

Wang, Yaqin

2017-07-01

Language can be regarded as a system where different components fit together, according to Saussure [1]. Likewise, the central axiom of synergetic linguistic is that language is a self-organized and self-adapting system. One of its main concerns is to view language as ;a psycho-social phenomenon and a biological-cognitive one at the same time; [2, 760]. Based on this assumption, Liu, Xu and Liang propose a novel approach, i.e., dependency distance, to study the general tendency hidden beneath diverse human languages [3]. As the authors describe in sections 1-3, variations within and between human languages all show the similar tendency towards dependency distance minimization (DDM). In sections 4-5, they introduce certain syntactic patterns related to both short and long dependency distances. However, the effect of genre seems to be given less sufficient attention by the authors. A study suggests that different distributions of closeness and degree centralities across genres can broaden the understanding of dependency distance distribution [4]. Another one shows that different genres have different parameters in terms of modeling dependency distance distribution [5]. Further research on the genre variation, therefore, can provide additional support for this issue.

Electric potential structures and propagation of electron beams injected from a spacecraft into a plasma

International Nuclear Information System (INIS)

Singh, Nagendra; Hwang, K.S.

1988-01-01

The propagation of electron beams injected from a spacecraft into an ambient plasma and the associated potential structures are investigated by one-dimensional Vlasov simulations. For moderate beams, for which the time average spacecraft potential (Φ sa ) lies in the range T e much-lt eΦ sa approx-lt W B , where T e is the electron temperature in energy units and W B is the average beam energy, a double layer forms near the beam head which propagates into the ambient plasma much more slowly than the initial beam velocity. The double layer formation is being reported for the first time. For weak beams, for which |eΦ sa | approx-lt T e , the beam propagates with the initial beam velocity, and no double layer formation occurs. On the other hand, for strong beams for which eΦ sa > W B , the bulk of the beam is returned to the spacecraft, and the main feature of the potential structure is a sheath formation with an intense electric field limited to distances d near the spacecraft surface. These features of the potential structures are compared with those seen in laboratory and space experiments on electron beam injections

REPRESENTATIONS OF DISTANCE: DIFFERENCES IN UNDERSTANDING DISTANCE ACCORDING TO TRAVEL METHOD

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Gunvor Riber Larsen

2017-12-01

Full Text Available This paper explores how Danish tourists represent distance in relation to their holiday mobility and how these representations of distance are a result of being aero-mobile as opposed to being land-mobile. Based on interviews with Danish tourists, whose holiday mobility ranges from the European continent to global destinations, the first part of this qualitative study identifies three categories of representations of distance that show how distance is being ‘translated’ by the tourists into non-geometric forms: distance as resources, distance as accessibility, and distance as knowledge. The representations of distance articulated by the Danish tourists show that distance is often not viewed in ‘just’ kilometres. Rather, it is understood in forms that express how transcending the physical distance through holiday mobility is dependent on individual social and economic contexts, and on whether the journey was undertaken by air or land. The analysis also shows that being aeromobile is the holiday transportation mode that removes the tourists the furthest away from physical distance, resulting in the distance travelled by air being represented in ways that have the least correlation, in the tourists’ minds, with physical distance measured in kilometres.

Crack formation and crack propagation under multiaxial mechanical and thermal stresses. Proceedings

International Nuclear Information System (INIS)

1993-01-01

The 25th meeting of the DV Fracture Group was held on 16/17 February 1993 at Karlsruhe Technical University. The main topic, ''Crack formation and crack propagation under multiaxial mechanical and thermal stresses'', was discussed by five invited papers (by K.J. Miller, D. Loehe, H.A. Richard, W. Brocks, A. Brueckner-Foit) and 23 short papers. The other 21 papers were devoted to various domains of fracture mechanics, with emphasis on elastoplastic fracture mechanics. (orig./MM) [de

Test-particle simulations of SEP propagation in IMF with large-scale fluctuations

Science.gov (United States)

Kelly, J.; Dalla, S.; Laitinen, T.

2012-11-01

The results of full-orbit test-particle simulations of SEPs propagating through an IMF which exhibits large-scale fluctuations are presented. A variety of propagation conditions are simulated - scatter-free, and scattering with mean free path, λ, of 0.3 and 2.0 AU - and the cross-field transport of SEPs is investigated. When calculating cross-field displacements the Parker spiral geometry is accounted for and the role of magnetic field expansion is taken into account. It is found that transport across the magnetic field is enhanced in the λ =0.3 AU and λ =2 AU cases, compared to the scatter-free case, with the λ =2 AU case in particular containing outlying particles that had strayed a large distance across the IMF. Outliers are catergorized by means of Chauvenet's criterion and it is found that typically between 1 and 2% of the population falls within this category. The ratio of latitudinal to longitudinal diffusion coefficient perpendicular to the magnetic field is typically 0.2, suggesting that transport in latitude is less efficient.

Finding the multipath propagation of multivariable crude oil prices using a wavelet-based network approach

Science.gov (United States)

Jia, Xiaoliang; An, Haizhong; Sun, Xiaoqi; Huang, Xuan; Gao, Xiangyun

2016-04-01

The globalization and regionalization of crude oil trade inevitably give rise to the difference of crude oil prices. The understanding of the pattern of the crude oil prices' mutual propagation is essential for analyzing the development of global oil trade. Previous research has focused mainly on the fuzzy long- or short-term one-to-one propagation of bivariate oil prices, generally ignoring various patterns of periodical multivariate propagation. This study presents a wavelet-based network approach to help uncover the multipath propagation of multivariable crude oil prices in a joint time-frequency period. The weekly oil spot prices of the OPEC member states from June 1999 to March 2011 are adopted as the sample data. First, we used wavelet analysis to find different subseries based on an optimal decomposing scale to describe the periodical feature of the original oil price time series. Second, a complex network model was constructed based on an optimal threshold selection to describe the structural feature of multivariable oil prices. Third, Bayesian network analysis (BNA) was conducted to find the probability causal relationship based on periodical structural features to describe the various patterns of periodical multivariable propagation. Finally, the significance of the leading and intermediary oil prices is discussed. These findings are beneficial for the implementation of periodical target-oriented pricing policies and investment strategies.

Forecasting Method for Urban Rail Transit Ridership at Station Level Using Back Propagation Neural Network

Directory of Open Access Journals (Sweden)

Junfang Li

2016-01-01

Full Text Available Direct forecasting method for Urban Rail Transit (URT ridership at the station level is not able to reflect nonlinear relationship between ridership and its predictors. Also, population is inappropriately expressed in this method since it is not uniformly distributed by area. In this paper, a new variable, population per distance band, is considered and a back propagation neural network (BPNN model which can reflect nonlinear relationship between ridership and its predictors is proposed to forecast ridership. Key predictors are obtained through partial correlation analysis. The performance of the proposed model is compared with three other benchmark models, which are linear model with population per distance band, BPNN model with total population, and linear model with total population, using four measures of effectiveness (MOEs, maximum relative error (MRE, smallest relative error (SRE, average relative error (ARE, and mean square root of relative error (MSRRE. Also, another model for contribution rate of population per distance band to ridership is formulated based on the BPNN model with nonpopulation variables fixed. Case studies with Japanese data show that BPNN model with population per distance band outperforms other three models and the contribution rate of population within special distance band to ridership calculated through the contribution rate model is 70%~92.9% close to actual statistical value. The result confirms the effectiveness of models proposed in this paper.

Directionality and Orientation Effects on the Resistance to Propagating Shear Failure

Science.gov (United States)

Leis, B. N.; Barbaro, F. J.; Gray, J. M.

Hydrocarbon pipelines transporting compressible products like methane or high-vapor-pressure (HVP) liquids under supercritical conditions can be susceptible to long-propagating failures. As the unplanned release of such hydrocarbons can lead to significant pollution and/or the horrific potential of explosion and/or a very large fire, design criteria to preclude such failures were essential to environmental and public safety. Thus, technology was developed to establish the minimum arrest requirements to avoid such failures shortly after this design concern was evident. Soon after this technology emerged in the early 1970sit became evident that its predictions were increasinglynon-conservative as the toughness of line-pipe steel increased. A second potentially critical factor for what was a one-dimensional technology was that changes in steel processing led to directional dependence in both the flow and fracture properties. While recognized, this dependence was tacitly ignored in quantifying arrest, as were early observations that indicated propagating shear failure was controlled by plastic collapse rather than by fracture processes.

Phase mixing of transverse oscillations in the linear and nonlinear regimes for IFR relativistic electron beam propagation

International Nuclear Information System (INIS)

Shokair, I.R.

1991-01-01

Phase mixing of transverse oscillations changes the nature of the ion hose instability from an absolute to a convective instability. The stronger the phase mixing, the faster an electron beam reaches equilibrium with the guiding ion channel. This is important for long distance propagation of relativistic electron beams where it is desired that transverse oscillations phase mix within a few betatron wavelengths of injection and subsequently an equilibrium is reached with no further beam emittance growth. In the linear regime phase mixing is well understood and results in asymptotic decay of transverse oscillations as 1/Z 2 for a Gaussian beam and channel system, Z being the axial distance measured in betatron wavelengths. In the nonlinear regime (which is likely mode of propagation for long pulse beams) results of the spread mass model indicate that phase mixing is considerably weaker than in the regime. In this paper we consider this problem of phase mixing in the nonlinear regime. Results of the spread mass model will be shown along with a simple analysis of phase mixing for multiple oscillator models. Particle simulations also indicate that phase mixing is weaker in nonlinear regime than in the linear regime. These results will also be shown. 3 refs., 4 figs

PROTON HEATING IN SOLAR WIND COMPRESSIBLE TURBULENCE WITH COLLISIONS BETWEEN COUNTER-PROPAGATING WAVES

Energy Technology Data Exchange (ETDEWEB)

He, Jiansen; Tu, Chuanyi; Wang, Linghua; Pei, Zhongtian [School of Earth and Space Sciences, Peking University, Beijing, 100871 (China); Marsch, Eckart [Institute for Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, D-24118 Kiel (Germany); Chen, Christopher H. K. [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom); Zhang, Lei [Sate Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing 100190 (China); Salem, Chadi S.; Bale, Stuart D., E-mail: jshept@gmail.com [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

2015-11-10

Magnetohydronamic turbulence is believed to play a crucial role in heating laboratory, space, and astrophysical plasmas. However, the precise connection between the turbulent fluctuations and the particle kinetics has not yet been established. Here we present clear evidence of plasma turbulence heating based on diagnosed wave features and proton velocity distributions from solar wind measurements by the Wind spacecraft. For the first time, we can report the simultaneous observation of counter-propagating magnetohydrodynamic waves in the solar wind turbulence. As opposed to the traditional paradigm with counter-propagating Alfvén waves (AWs), anti-sunward AWs are encountered by sunward slow magnetosonic waves (SMWs) in this new type of solar wind compressible turbulence. The counter-propagating AWs and SWs correspond, respectively, to the dominant and sub-dominant populations of the imbalanced Elsässer variables. Nonlinear interactions between the AWs and SMWs are inferred from the non-orthogonality between the possible oscillation direction of one wave and the possible propagation direction of the other. The associated protons are revealed to exhibit bi-directional asymmetric beams in their velocity distributions: sunward beams appear in short, narrow patterns and anti-sunward in broad extended tails. It is suggested that multiple types of wave–particle interactions, i.e., cyclotron and Landau resonances with AWs and SMWs at kinetic scales, are taking place to jointly heat the protons perpendicular and in parallel.

Long-Distance Rescue and Slow Extinction Dynamics Govern Multiscale Metapopulations.

Science.gov (United States)

Huth, Géraldine; Haegeman, Bart; Pitard, Estelle; Munoz, François

2015-10-01

Rare long-distance dispersal is known to be critical for species dynamics, but how the interplay between short- and long-distance colonization influences regional persistence in a fragmented habitat remains poorly understood. We propose a metapopulation model that combines local colonization within habitat islands and long-distance colonization between islands. We study how regional occupancy dynamics are affected by the multiscale colonization process. We find that the island size distribution (ISD) is a key driver of the long-term occupancy dynamics. When the ISD is heterogeneous-that is, when the size of islands is variable-we show that extinction dynamics become very slow. We demonstrate that this behavior is unrelated to the well-known extinction debt near the critical extinction threshold. Hence, this finding questions the equivalence between extinction debt and critical transitions in the context of metapopulation collapse. Furthermore, we show that long-distance colonization can rescue small islands from extinction and sustain a steady regional occupancy. These results provide novel theoretical and practical insights into extinction dynamics and persistence in fragmented habitats and are thus relevant for the design of conservation strategies.

Psychological distance modulates the performance of the embodiment effect: Evidence from behavioral and ERP studies.

Science.gov (United States)

Wang, Hanlin; Mo, Lei; Luo, Qiuling; Xiang, Yanhui; Hu, Yunyang

2016-04-01

Research on embodied cognition suggests the ubiquity of embodiment effects during interaction with the environment. However, construal level theory (CLT) holds that these effects could be moderated by the psychological distance between self and objects and are attenuated by higher-level mental construal. The current research explored the "action-evaluation" embodiment effect in the evaluation of words located at different spatial distances. Results showed that for "short-distance" words, the response model conflicted with this embodiment effect slower reaction time and induced a larger P2 component than the opposite response model. However, evaluation of "long-distance" words was not significantly influenced by the response model. The results are consistent with CLT and suggest that the action-evaluation embodiment effect influences the coding and execution of evaluating actions, but only for stimuli at close psychological distance locations. © 2015 Society for Psychophysiological Research.

Proceedings of the Twentieth NASA Propagation Experimenters Meeting (NAPEX XX) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop

Science.gov (United States)

Golshan, Nassar (Editor)

1996-01-01

The NASA Propagation Experimenters (NAPEX) Meeting and associated Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop convene yearly to discuss studies supported by the NASA Propagation Program. Representatives from the satellite communications (satcom)industry, academia, and government with an interest in space-ground radio wave propagation have peer discussion of work in progress, disseminate propagation results, and interact with the satcom industry. NAPEX XX, in Fairbanks, Alaska, June 4-5, 1996, had three sessions: (1) "ACTS Propagation Study: Background, Objectives, and Outcomes," covered results from thirteen station-years of Ka-band experiments; (2) "Propagation Studies for Mobile and Personal Satellite Applications," provided the latest developments in measurement, modeling, and dissemination of propagation phenomena of interest to the mobile, personal, and aeronautical satcom industry; and (3)"Propagation Research Topics," covered a range of topics including space/ground optical propagation experiments, propagation databases, the NASA Propagation Web Site, and revision plans for the NASA propagation effects handbooks. The ACTS Miniworkshop, June 6, 1996, covered ACTS status, engineering support for ACTS propagation terminals, and the ACTS Propagation Data Center. A plenary session made specific recommendations for the future direction of the program.

Light propagation through black-hole lattices

Energy Technology Data Exchange (ETDEWEB)

Bentivegna, Eloisa [Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via S. Sofia 64, 95123 Catania (Italy); Korzyński, Mikołaj [Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Hinder, Ian; Gerlicher, Daniel, E-mail: eloisa.bentivegna@unict.it, E-mail: korzynski@cft.edu.pl, E-mail: ian.hinder@aei.mpg.de, E-mail: daniel.gerlicher@tum.de [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, D-14476 Golm (Germany)

2017-03-01

The apparent properties of distant objects encode information about the way the light they emit propagates to an observer, and therefore about the curvature of the underlying spacetime. Measuring the relationship between the redshift z and the luminosity distance D {sub L} of a standard candle, for example, yields information on the Universe's matter content. In practice, however, in order to decode this information the observer needs to make an assumption about the functional form of the D {sub L}( z ) relation; in other words, a cosmological model needs to be assumed. In this work, we use numerical-relativity simulations, equipped with a new ray-tracing module, to numerically obtain this relation for a few black-hole-lattice cosmologies and compare it to the well-known Friedmann-Lema(ȋtre-Robertson-Walker case, as well as to other relevant cosmologies and to the Empty-Beam Approximation. We find that the latter provides the best estimate of the luminosity distance and formulate a simple argument to account for this agreement. We also find that a Friedmann-Lema(ȋtre-Robertson-Walker model can reproduce this observable exactly, as long as a time-dependent cosmological constant is included in the fit. Finally, the dependence of these results on the lattice mass-to-spacing ratio μ is discussed: we discover that, unlike the expansion rate, the D {sub L}( z ) relation in a black-hole lattice does not tend to that measured in the corresponding continuum spacetime as 0μ → .

Human-Structure Dynamic Interaction during Short-Distance Free Falls

Directory of Open Access Journals (Sweden)

E. Shahabpoor

2016-01-01

Full Text Available The dynamic interactions of falling human bodies with civil structures, regardless of their potentially critical effects, have sparsely been researched in contact biomechanics. The physical contact models suggested in the existing literature, particularly for short-distant falls in home settings, assume the human body falls on a “rigid” (not vibrating ground. A similar assumption is usually made during laboratory-based fall tests, including force platforms. Based on observations from a set of pediatric head-first free fall tests, the present paper shows that the dynamics of the grounded force plate are not always negligible when doing fall test in a laboratory setting. By using a similar analogy for lightweight floor structures, it is shown that ignoring the dynamics of floors in the contact model can result in an up to 35% overestimation of the peak force experienced by a falling human. A nonlinear contact model is suggested, featuring an agent-based modelling approach, where the dynamics of the falling human and the impact object (force plate or a floor structure here are each modelled using a single-degree-of-freedom model to simulate their dynamic interactions. The findings of this research can have wide applications in areas such as impact biomechanics and sports science.

Enhanced oxygen dissociation in a propagating constricted discharge formed in a self-pulsing atmospheric pressure microplasma jet

Science.gov (United States)

Schröder, Daniel; Burhenn, Sebastian; Kirchheim, Dennis; Schulz-von der Gathen, Volker

2013-11-01

We report on the propagation of a constricted discharge feature in a repetitively self-pulsing microplasma jet operated in helium with a 0.075 vol% molecular oxygen admixture in ambient air environment. The constricted discharge is about 1 mm in width and repetitively ignites at the point of smallest electrode distance in a wedge-shaped electrode configuration, propagates through the discharge channel towards the nozzle, extinguishes, and re-ignites at the inlet at frequencies in the kHz range. It co-exists with a homogeneous, volume-dominated low temperature (T ⋍ 300 K) α-mode glow. Time-resolved measurements of nitrogen molecule C-state and nitrogen molecule ion B-state emission bands reveal an increase of the rotational temperature within the constricted discharge to about 600 K within 50 µs. Its propagation velocity was determined by phase-resolved diagnostics to be similar to the gas velocity, in the order of 40 m s-1. Two-photon absorption laser-induced fluorescence spectroscopy synchronized to the self-pulsing reveals spatial regions of increased oxygen atom densities co-propagating with the constricted discharge feature. The generated oxygen pulse density is about ten times higher than in the co-existing homogeneous α-mode. Densities reach about 1.5 × 1016 cm-3 at average temperatures of 450 K at the nozzle. This enhanced dissociation of about 80% is attributed to the continuous interaction of the constricted discharge to the co-propagating gas volume.

Conflict Resolution for Product Performance Requirements Based on Propagation Analysis in the Extension Theory

Directory of Open Access Journals (Sweden)

Yanwei Zhao

2014-01-01

Full Text Available Traditional product data mining methods are mainly focused on the static data. Performance requirements are generally met as possible by finding some cases and changing their structures. However, when one is satisfied with the structures changed, the other effects are not taken into account by analyzing the correlations; that is, design conflicts are not identified and resolved. An approach to resolving the conflict problems is proposed based on propagation analysis in Extension Theory. Firstly, the extension distance is improved to better fit evaluating the similarity among cases, then, a case retrieval method is developed. Secondly, the transformations that can be made on selected cases are formulated by understanding the conflict natures in the different performance requirements, which leads to the extension transformation strategy development for coordinating conflicts using propagation analysis. Thirdly, the effects and levels of propagation are determined by analyzing the performance values before and after the transformations, thus the co-existing conflict coordination strategy of multiple performances is developed. The method has been implemented in a working prototype system for supporting decision-making. And it has been demonstrated the feasible and effective through resolving the conflicts of noise, exhaust, weight and intake pressure for the screw air compressor performance design.

Gender and distance influence performance predictors in young swimmers

OpenAIRE

Mezzaroba, Paulo Victor; Papoti, Marcelo; Machado, Fabiana Andrade

2013-01-01

Predictors of performance in adult swimmers are constantly changing during youth especially because the training routine begins even before puberty in the modality. Therefore this study aimed to determine the group of parameters that best predict short and middle swimming distance performances of young swimmers of both genders. Thirty-three 10-to 16-years-old male and female competitive swimmers participated in the study. Multiple linear regression (MLR) was used considering mean speed of max...

Light propagation in linear optical media

CERN Document Server

Gillen, Glen D; Guha, Shekhar

2013-01-01

Light Propagation in Linear Optical Media describes light propagation in linear media by expanding on diffraction theories beyond what is available in classic optics books. In one volume, this book combines the treatment of light propagation through various media, interfaces, and apertures using scalar and vector diffraction theories. After covering the fundamentals of light and physical optics, the authors discuss light traveling within an anisotropic crystal and present mathematical models for light propagation across planar boundaries between different media. They describe the propagation o