1,721,088 research outputs found
New York University Club, 1962 -- Miscellaneous, Assorted Letters and Photographs -- letter, 1962-01-25
No full textLetter from Walmsley, C. A. to Sabin, Albert B. dated 1962-01-25.Sabin Collection Fair Use Policy</a
The disk-outflow system around the high-mass (proto)star IRAS 20126+4104
No full textWe have used the Pico Veleta 30-m telescope and the Plateau de Bure interferometer to obtain maps of the molecular gas associated with IRAS 20126+4104 in 11 rotational transitions. We also present near infrared images of the same region taken with the TIRGO and NOT telescopes. A molecular clump centred on the H_2_O masers associated with the IRAS source is found. A molecular bipolar outflow is clearly evidenced by the interferometer maps in the HCO^+^(1-0) line, originating at the center of the clump; also, the images in the K-band continuum and in the H_2_ v=1->0 S(1) vibrational line trace the same bipolar structure seen in HCO^+^. A flattened structure elongated in the direction perpendicular to the outflow axis is seen in the CH_3_CN(5-4) line: we interpret this as a rotating disk with a very young massive early type star at its centre. We conclude that IRAS 20126+4104 represents a beautiful example of a disk-outflow system associated with an early type (proto)star, prior to the development of an ultracompact HII region
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
Near infrared spectra of the Orion bar
No full textWe have used the LONGSP spectrometer on the 1.5-m TIRGO telescope to obtain long slit spectra in the J, H, and K wavelength bands towards two positions along the Orion bar. These data have been supplemented with images made using the ARNICA camera mounted on TIRGO as well as with an ESO NTT observation carried out by Dr A. Moorwood. We detect a variety of transitions of hydrogen, helium, OI, FeII, FeIII, and H_2. From our molecular hydrogen data, we conclude that densities are moderate (3-6x 10(4) cm(-3) ) in the layer responsible for the molecular hydrogen emission and give no evidence for the presence of dense neutral clumps. We also find that the molecular hydrogen bar is likely to be tilted by ~ 10 degrees relative to the line of sight. We discuss the relative merits of several models of the structure of the bar and conclude that it may be split into two structures separated by 0.2-0.3 parsec along the line of sight. It also seems likely to us that in both structures, density increases along a line perpendicular to the ionization front which penetrates into the neutral gas. We have used the 1.317mum OI line to estimate the FUV radiation field incident at the ionization front and find values of 1-3x 10(4) greater than the average interstellar field. From [FeII] line measurements, we conclude that the electron density in the ionized layer associated with the ionization front is of order 10(4) \percc. Finally, our analysis of the helium and hydrogen recombination lines implies essential coincidence of the helium and hydrogen Stromgren spheres
The structure of the Orion bar
No full textWe have obtained NIR spectral line maps of a limited region around the Orion Bar ionization front using the red and blue grisms of SOFI on the ESO NTT telescope. The wavelength range covered was from 0.95 to 2.3 μm. In addition to many well studied features, we detected two lines at 1.07 and 1.17 {mum } due to recombination to CI which have excitations above 60000 cm-1. We also observe several features at around 1 micron of atomic nitrogen (at still higher excitations) which we believe are caused by fluorescence of UV lines at approximately 955 Å in gas within the ionization front. We give a brief analysis of this process showing that one can infer the relative UV intensities incident upon the ionization front on the basis of the NIR spectra. Analogously, the spatial distribution of the fluorescent OI 1.317 {mum } line allows one to infer the geometry of the ionization front. We consider various geometries and conclude that the Orion Bar is most likely to be a cylinder or filament in the plane of the sky. Maps in the 9840 Å CI line were also obtained and compared with the corresponding intensity distribution in C91alpha from Wyrowski et al. (1997). These are emitted from the same general area but show differences in detail which are likely partly to be due to patchy extinction. The CI NIR line correlates well with molecular hydrogen emission away from the high density high radiation field layers of the Bar. The measured CI line ratios (in particular the ratio of the 0.984 and 1.07 {mum } lines) suggest higher temperatures in the C+ layer than allowed from the measured radio line width. The explanation for this discrepancy is not clear but it points up the need for observations in the NIR with higher spectral resolution and in the radio with higher spatial resolution
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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