1,721,375 research outputs found
Esistono relazioni stimabili tra dimensione ed efficienza delle istituzioni e crescita della produttività? Un esercizio nello spirito di D.C. North
No full textA note about the relationship among transaction costs, institutions and productivity growth
No full textDo estimable relations exist between size and efficiency of institutions and growth of productivity? An exercise in the spirit of D. C. North
No full textLaboratory and space spectroscopy of DCO+
No full textThe rotational spectra of DCO+ and its two isotopomers D13CO+ and DC18O+, produced in a negative glow discharge cell, have been recorded in the 137-792 GHz region, which includes lines from J = 2-1 up to J = 11-10. The determined rotational and centrifugal distortion constants allow to predict the DCO+ rotational spectrum up to 1000 GHz with an accuracy of 1 part in 10^8 or better. This is important for kinematic studies of dense molecular cloud cores and for future far-infrared observations. We also report on the first detection of the hyperfine structure of the DCO+ (1-0) line made at the IRAM 30 m antenna, toward the quiescent starless cloud core L1512, in the Taurus Molecular Cloud. We point out that this is the first observation of the hyperfine splitting due to the deuteron. This allowed us to quantify the effects of the hyperfine splitting on the line width determination; if the hyperfine structure is not taken into account in the line fit, the DCO+ (1-0) line width is overestimated by a significant factor (>=2)
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
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
Detection of N15NH+ in L1544
No full textContext. Excess levels of 15N isotopes which have been detected in primitive solar system materials are explained as a remnant of interstellar chemistry which took place in regions of the protosolar nebula.
Aims. Chemical models of nitrogen fractionation in cold clouds predict an enhancement in the gas-phase abundance of 15N-bearing molecules, thus we have searched for 15N variants of the N2H+ ion in L1544, which is one of the best candidate sources for detection owing to its low central core temperature and high CO depletion.
Methods. With the IRAM 30m telescope we have obtained deep integrations of the N15NH+ (1−0) line at 91.2 GHz.
Results. The N15NH+ (1−0) line has been detected toward the dust emission peak of L1544. The 14N/15N abundance ratio in N15NH+
resulted 446 ± 71, very close to the protosolar value of ∼ 450, higher than the terrestrial ratio of ∼270, and significantly lower than the lower limit in L1544 found by Gerin et al. (2009, ApJ, 570, L101) in the same object using ammonia isotopologues
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