1,721,051 research outputs found
Soft-x-ray emission from small-sized Ne clusters heated by intense, femtosecond laser pulses
No full textSoft-x-ray emission from a cryogenically cooled Ne jet irradiated; by intense, 25-fs laser pulses was measured. The Ne spectrum started to drastically change in emitting ions from Ne5+ to Ne7+ below the preexpansion temperature of - 120 degrees C. The significant change in the spectrum is attributed to the collisional heating of small-sized Ne clusters formed in the cooled jet. The increase of the laser pulse length from 25 fs to 100 fs resulted in further increase of x-ray emission from Ne7+ states.This research was supported by the Ministry of Science and Technology of Korea through the Creative Research Initiative Program
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Enhancement of soft x-ray emission from a cryogenically cooled Ar gas jet irradiated by 25 fs laser pulse
No full textSoft x-ray spectra (40-180 Angstrom) produced by the interaction of 25 fs laser pulses at an intensity of similar to 7 x 10(16) W/cm(2) with a cryogenically cooled Ar gas jet have been measured. New spectral lines from Ar8+ and Ar9+ charge states appeared with decreasing gas temperature. Nonlinear increase of x-ray line emission from Ar7+, Ar8+, and Ar9+ was observed with cooling, which saturated below certain temperature. The drastic change in the spectrum is attributed to efficient collisional heating and collisional ionization of growing (10(2)-10(3) atoms) Ar clusters from the cooled jet. (C) 2000 American Institute of Physics. [S0003-6951(00)02614-0].This research was supported by the Ministry of Science and Technology of Korea through the Creative Research Initiative Program
Observation of enhanced soft x-ray emission using nitrogen clusters ionized by intense, femtosecond laser
No full textWe report soft x-ray spectra (5-18 nm) from a cryogenically cooled nitrogen gas jet irradiated by 28-fs-laser pulses at an intensity of similar to7 x 10(16) W/cm(2). While the time-integrated spectrum obtained at room temperature showed exclusively transitions in N4+ ions, spectral lines from N5+ and N6+ charge states appeared with cooling. Rapid, nonlinear increase of x-ray emission on lines from N4+, N5+, and N6+ has been observed by lowering the preexpansion gas temperature. (C) 2003 American Institute of Physics.This research was supported by the Ministry of Science
and Technology of Korea through the Creative Research Initiative
Program. The visit of T. Mocek to KAIST was supported
by the Korea Science and Engineering Foundation
and by the Czech Ministry of Education, Youth and Sports
through the Laser Plasma Research Center (Project LN00A100
Investigation of soft X-ray emission from Ar clusters heated by ultrashort laser pulses
No full textWe report soft X-ray spectra (4-18 nm) produced by the interaction of 25-100-fs laser pulses at an intensity of up to 7 X 10(16) W/cm(2) with a cryogenically cooled Ar gas jet. New spectral lines from Ar8+, Ar9+, and Ar10+ charge states appeared with decreasing preexpansion gas temperature. A nonlinear increase of X-ray line emission from Ar7+, Ar8+, and Ar9+ was observed with cooling, which saturated below a certain temperature. The drastic change in the spectrum is attributed to efficient collisional heating and collisional ionization of growing, small- to medium-sized (10(2)-10(3) atoms) Ar clusters from the cooled jet. When the laser pulse was extended from 25 to 100 fs we observed considerably stronger emission on lines from high charge states, such as Ar8+, Ar9+, and Ar10+, which suggests that the resonance absorption condition could be reached for the 100-fs pulse
Interaction of intense, femtosecond laser pulse with small-sized Ne clusters
No full textWe report the first observation of X-ray emission (4 - 18 nm) from small-sized Ne clusters heated by high-intensity, 25-100 A laser pulses. The Ne spectrum started to drastically change in emitting ions from Ne5+ to Ne7+ below the pre-expansion temperature of -120 degreesC. The significant change in the spectrum is attributed to the collisional heating of small-sized Ne clusters formed in the cryogenically cooled gas jet. Though the size of Ne clusters in our experiment is estimated to be quite small, i.e. a few tens of atoms per cluster, and thus they were undetectable by the standard Rayleigh scattering technique, the. appearance of spectral lines of Ne7+ ions presented clear evidence of collisional heating that occurred in near-solid-density cluster. By extending the laser pulse length from 25 fs to 100 fs, considerably higher X-ray yield from the highest charge state Ne7+ was observed in the covered spectral region, showing more efficient absorption of 100 fs laser pulse
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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