نتایج جستجو برای: electric pulse

تعداد نتایج: 228782  

Journal: :Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention 2006
Nanfei Sun Ioannis T. Pavlidis Marc Garbey Jin Fei

In the present paper, we propose a new pulse measurement methodology based on thermal imaging (contact-free). The method capitalizes both on the thermal undulation produced by the traveling pulse as well as the periodic expansion of the compliant vessel wall. The paper reports experiments on 34 subjects, where it compares the performance of the new pulse measurement method to the one we reporte...

Journal: :Physical review letters 2015
Sebastian Trippel Terry Mullins Nele L M Müller Jens S Kienitz Rosario González-Férez Jochen Küpper

We demonstrate strong laser-field-free orientation of absolute-ground-state carbonyl sulfide molecules. The molecules are oriented by the combination of a 485-ps-long nonresonant laser pulse and a weak static electric field. The edges of the laser pulse create a coherent superposition of two rotational states resulting in revivals of strong transient molecular orientation after the laser pulse....

Journal: :Journal of applied microbiology 2000
M Tyurin R Padda K X Huang S Wardwell D Caprette G N Bennett

Molecular biological improvement of industrial solventogenic clostridia could be enhanced by a higher efficiency of electrotransformation. In this research, we used a new approach to determine the frequency spontaneously generated by Clostridium acetobutylicum ATCC 824 cells during the application of a square high-voltage pulse. Once the frequency of 100 kHz was determined we transformed clostr...

Journal: :Physical review letters 2002
A Wetzels A Gürtler L D Noordam F Robicheaux C Dinu H G Muller M J J Vrakking W J van der Zande

The asymptotic velocity distribution of electrons ionized in half-cycle-pulse excitation of high Rydberg states (n=34), placed in a static electric field, is studied using electron velocity-map imaging. At weak half-cycle pulse strengths, the electrons escape over the saddle point in the potential. For strong half-cycle pulses, the electrons are emitted in the direction of the field kick. The m...

Journal: :Optics letters 2003
Johan Mauritsson Rodrigo López-Martens Anne L'Huillier Kenneth J Schafer

We propose a novel method for completely characterizing ultrashort pulses at extreme-ultraviolet (XUV) wavelengths by adapting the technique of spectral phase interferometry for direct electric-field reconstruction to this spectral region. Two-electron wave packets are coherently produced by photoionizing atoms with two time-delayed replicas of the XUV pulse. For one of the XUV pulses, photoion...

1998
F. Robicheaux L. D. Noordam

When the outer electron of an alkali atom in an electric field is laser excited just above the field-induced ionization threshold, the electron ejection will not be instantaneous. Calculations show there are a number of energy regions where, upon short-pulse laser excitation, the atom will eject a train of electron probability pulses with the pulses being nearly equally spaced in time. This sys...

1999
M. A. Uman G. R. Hoffman

Regular bursts of electric field radiation pulses produced by three multiple-stroke cloud-to-ground discharges recorded in 1991 at the NASA Kennedy Space Center are analyzed. The bursts are similar in the number of pulses per burst and inter-pulse intervals to the “multiple burst” component (so-called component H) of the standard lightning environment for the design and testing of aerospace veh...

Journal: :Optics letters 2012
Justin Ratner Günter Steinmeyer Tsz Chun Wong Randy Bartels Rick Trebino

We simulate multishot intensity-and-phase measurements of unstable trains of complex ultrashort pulses using second-harmonic-generation (SHG) frequency-resolved optical gating (FROG) and spectral-phase interferometry for direct electric-field reconstruction (SPIDER). Both techniques fail to see the pulse structure. But FROG yields the correct average pulse duration and suggests the instability ...

1995
D. A. Ivanov H. W. Lee L. S. Levitov

We study counting statistics of electric current pumped by pulses of an external field. The fluctuations depend on the pulse shape, and can be minimized by choosing the pulse shape properly. For an optimal pulse shape, the fluctuations are reduced to the dc level, i.e., they do not depend on the duty cycle of the signal. We develop an approach that allows to calculate all counting statistics fo...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2002
L L Bonilla R Escobedo F J Higuera

The Kroemer model for the Gunn effect in a circular geometry (Corbino disks) has been numerically solved. The results have been interpreted by means of asymptotic calculations. Above a certain onset dc voltage bias, axisymmetric pulses of the electric field are periodically shed by an inner circular cathode. These pulses decay as they move towards the outer anode, which they may not reach. As a...

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