1,720,961 research outputs found
Molecules in the postrecombination universe and microwave background anisotropies
No full textWe consider the effects of the elastic Thomson scattering between cosmic background radiation (CBR) and primordial molecules, like H2, H2(+), HeH(+), HD, HD(+), LiH, LiH(+): primary CBR anisotropies may be erased or attenuated for angular scales is less than or equal to 10 deg up to 50 deg and frequencies nu is less than or equal to 50 GHz, if LiH primordial abundance exceed 10-10(H). Conversely, CBR anisotropy data may be used to put stringent upper limits on the abundance of primordial elements. Already available data on CBR anisotropies at various frequencies impose primordial LiH abundance to be not larger than 2 x 10-9(H). Secondary anisotropies are expected at arcsecond-arcminute angular scales, due to the anisotropic scattering by moving molecular clouds: they are stronger in the millimetric region and close to be detected in IRAM 200 GHz observations
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
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
Molecular signals from primordial clouds at high redshift
No full textThe possibility of detecting cosmological signals from the postrecombination universe is one of the main aims of modern cosmology. In a previous paper we emphasized the role that elastic resonant scattering through WH molecules can have in dumping primary cosmic background radiation (CBR) anisotropies and raising secondary signals. Here we extend our analysis to all the evolutionary stages of a primordial cloud, starting with the linear phase, through the turnaround, and to the nonlinear collapse. We have done calculations for protoclouds in a cold dark matter (CDM) scenario and, more generally, for a set of clouds with various masses and various turnaround redshifts, in this case without referring to any particular structure formation scenario. We found that the first phase of collapse, for t/t(free-fall) = 0.05-0.2 is the best one for simultaneous detection of the first two LiH rotational lines. The observational frequency falls between 30 and 250 GHz, and the line width Delta nu/nu is between 10(-5) and 10(-4). As far as we know, this is the most favorable process to detect primordial clouds before they begin star formation processes
Enantioselective transport of D,L-phenylalanine and D,L-phenylglycine through a bulk liquid membrane containing cinchona alkaloid derivatives as chiral selectors
No full textDifferent cinchona derivatives were tested as chiral mobile carriers for enantioselective transport of D,L-phenylglycine and D,L-phenylalanine through a bulk organic liquid membrane (BLM). The effects of several parameters such as carrier nature, membrane solvent, buffer, solute and carrier concentrations on BLM enrichment were evaluated. Only D,L-phenylglycine is subjected to enantioselective transport at a certain degree; the maximum enantioselectivity ratio (the initial transport rates of the L-enantiomer relative to the antipode) was reached by employing O-allyl-N-(9-anthracenylmethyl) cinchonidinium bromide as carrier. In all cases the highest selectivity was observed during the initial stages of the process, indicating the rate of amino acid release from the source phase (SP) to the membrane organic phase (MP) as the driving factor. Chiral enrichment appeared to depend on thermodynamic factors more than on kinetic ones, since the complex formation was observed at (SP)/MP) interface, while complex decomposition was evidenced at (RP)/(MP) interface, where RP is receiving phase. The last phenomenon was promoted by H+ ions present in the RP
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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