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The electron energy distribution during HF pumping, a picture painted with all colors
Get PDFInternational audienceThe shape of the electron energy distribution has long been a central question in the field of high-frequency radio-induced optical emission experiments. This report presents estimates of the electron energy distribution function, fe(E), from 0 to 60 eV, based on optical multi-wavelength (6300, 5577, 8446, 4278Å) data and 930-MHz incoherent scatter radar measurements of ion temperature, electron temperature and electron concentration. According to our estimate, the electron energy distribution has a depression at around 2 eV, probably caused by electron excitation of vibrational states in N2, and a high energy tail that is clearly supra-thermal. The temporal evolution of the emissions indicates that the electron temperature still plays an important role in providing electrons with energies close to 2 eV. At the higher energies the electron energy distribution has a non-thermal tail. Keywords. Active experiments; Ionosphere atmosphere interaction; Ionospheric physic
Simulation of high energy tail of electron distribution function
Get PDFP(論文)This report presents Monte Carlo simulations of the electron energy distribution for alow ionized plasma interacting with the F-region neutral gas. The results show a depletion in theelectron distribution above 2 eV between 10 and 80 %, decreasing with altitude. The depletion ismainly due to electron energy loss to . This micro-physical energy transfer model gives goodagreement with optical observations of enhanced emissions from at 6300Å and EISCATUHF measurements of electron cooling during HF radio wave heating experiments. Someimplications for incoherent scatter spectra are derived. The results suggest that a weak(approximately 1000 times weaker than the ion-line) and wide (2 MHz) peak around +-1 MHz fromthe ion-line in the EISCAT VHF incoherent scatter spectrum should be a consequence of theelectron-neutral interaction.departmental bulletin pape
6300 Å Night Airglow in Winter
No full text221-224The photometric data of the 6300 A (O1 D) emission in the night airglow for the winter of 1980-81 at Patiala have been analyzed. The regular features of 6300 A emission line as determined from the experimental data have been used to formulate a numerical model. The computed and the normal experimental intensity curves for 6300 A night airglow show a good agreement. The anomalous features, i.e. enhancements are also studied in terms of their relationship with the movement of the F-laye
Photometric Observations of 5577 ? and 6300 ? Airglow During the I.G.Y.
No full textTwenty.one months' observation of the airglow from near Sydney, Australia, shows that (a) aurorae are detected 10� above the southern horizon at 6300 A whenever the magnetic disturbance index (K) reaches 5 but K must reach 7 before detection is certain at 5577 A; (b) the 6300 A zenith intensity increases rapidly with K once this equals or exceeds 4, but the 5577 A zenith intensity is independent of magnetic disturbance; (c) the zenith intensity of 5577 A tends to be a maximum at 03 hr local time; (d) the zenith intensity of 6300 A drops rapidly from dusk till 01 hr and then rises till dawn.</jats:p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Analysis of excitation of the 630.0 nm airglow during a heating experiment in Troms on February 16, 1999
Get PDF6300 Å night airglow enhancements in low latitudes
No full textAt low latitudes, in the nocturnal variation of 6300 Å night airglow, quite often increases in intensity followed by decreases are observed. Such 6300 Å enhancements are broadly classified under the two heads as 'pre-midnight' and 'post-midnight' enhancements, depending on their time of occurrence. From a large amount of data obtained at Mt. Abu, India, with three photoelectric photometers, these enhancements are studied and the dynamics of the ionosphere in low latitudes during those hours is investigated. It is shown that vertical downward movements of electrons is one of the main causes for these enhancements
Variations on the Author
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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