1,721,470 research outputs found
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
Antibiotics as ligands. Coordination behaviour of cycloserine towards cobalt (II), nickel (II), zinc (II), cadmium (II) and mercury (II) halides
No full textThe complexes of cycloserine, 4-amino-3-isoxazolidone, (Ccs) with cobalt(II), nickel(II), zinc(II), cadmium(II), and mercury(II) halides have been synthetized. Their structures have been assigned on the basis of analytical, conductivity, spectral (visible, i.r. and far-i.r.) and magnetic data. The ligand behaves as monodentate O-bonded. The position and multiplicity of the metal-halide stretching frequencies are discussed and used as a guide to the stereochemistry. The most convincing structural evidence for the cobalt derivatives is a predominantly planar environment for the chloro-complex with terminal ligands and terminal halides, while for the 1:3 complexes we could suggest a pentacoordinate structure with terminal both ligands and halides. The nickel(II) chloro- and bromo-derivatives seem to have a pseudo-tetrahedral symmetry, while the iodo-complex resulted pentacoordinate. Both the cobalt(II) and nickel(II) derivatives resulted high spin, with the exception of Co(Ccs)2Cl2. Tetrahedral monomeric and dimeric structures with bridging halide atoms, and pentacoordinate geometries are present in the zinc(II), cadmium(II), and mercury(II) complexes. The water resulted always uncoordinated lattice water. Assignments for the electronic spectra are proposed for all the above reported symmetries; the assignments for the metalligand and metal-halides stretching modes have also been made. We have never observed a metalinduced ring opening under the present experimental conditions
Preparation and studies of some antimony and bismuth trisdithiocarbamate and five-coordinate monohalobisdithiocarbamate derivatives
No full textThe complexes of antimony(III) and bismuth(III) with piperidinedithiocarbamate (Pipdtc), morpholinedithiocarbamate (Morphdtc) and thiomorpholinedithiocarbamate (Timdtc) of general formula M(Rdtc)3 have been prepared, and characterized by spectroscopic methods. The data show that the complexes have a distorted octahedral stereochemistry, this distortion being due to the stereochemically active lone-pair of electrons on the antimony and bismuth atoms.A new series of pentacoordinate complexes of general formula M(Rdtc)2X, M being antimony or bismuth, X a halogen and Rdtc the above dithiocarbamates, has been prepared by reacting the corresponding trisdithiocarbamates with chlorine, bromine and iodine. The compounds have been characterized by IR and electronic spectroscopy and molecular weight determinations. The infrared spectra suggest that each dithiocarbamate group coordinates as a bidentate ligand; the metal—halide and metal—sulphur stretching modes have also been assigned. The spectral data are discussed and compared with those of the corresponding trisdithiocarbamate derivatives. The molecular weight determinations indicate that the trisdithiocarbamate complexes are monomeric; for the monohalobisdithiocarbamates, the antimony derivatives are shown to be monomeric, while the bismuth derivatives tend to dimerize
Metal-ligand bonding in benzeneseleninato complexes of p- and d- block metals
No full textNew complexes of lead(II) and zirconium(IV) withmeta-andpara-substituted benzeneseleninic acids are reported and characterized by chemical analyses, spectroscopic methods and conductivity and magnetic measurements. The complexes are of the Pb(XC6H4SeO2)2 and ZrO(XC6H4SeO2)2 type; for zirconium(IV), working with a 1:4 metal:ligand stoichiometrical ratio, invariably the oxy derivative was obtained. The i.r. spectral data suggest that the complexes contain RSeO 2 – ligands acting as bidentate in O,O -seleninato complexes, Where possible, a tentative stereochemistry for the complexes is discussed on the basis of the results obtained
Synthesis and characterization of ruthenium dithiocarbamate complexes
No full textPiperidine carbodithioate (Pipdtc), morpholine-4-(Morphdtc), thiomorpholine-4-(Timdtc), piperazine-4-(Pzdtc) and N-methylpiperazine-4-carbodithioate (CH3-Pzdtc) complexes of ruthenium have been prepared and characterized by spectroscopic methods (IR and electronic spectra), magnetic susceptibilities and conductivity measurements. Where possible a tentative stereochemistry of the complexes is discussed based upon the obtained results. The dithiocarbamate ligands show in all the complexes a bidentate behaviour. A distorted octahedral geometry is proposed for the water containing 1:2 derivatives: in fact from a detailed analysis of the infrared spectra the water resulted always coordinated to the metal. The Pzdtc 1:2 derivative resulted polymeric octahedral with the NH group of the heterocyclic ring involved in the coordination
Five-coordinate low-spin cobalt (II) complexes with benzeneseleninato ions and ethylenediamine as ligands
No full textFive-coordinate bis(benzeneseleninato)tris(ethylenediamine) cobalt (II)complexes are obtained by reaction of Co(H2O)2 (XC6 H4 SeO2)2 complexes (X = H, p-Cl, m-CI, p-Br, ni-Br, p-Me,p-NO2) with ethylenediamine. The diaquo complexes (one mole)react with ethylenediamine (three moles)to form O-seleninato derivatives. Spectral and magnetic properties show that the complexes are low-spin (s = 1/2) and,on the basis of the electronic spectra a distorted trigonal geometry,D 3h , is suggested. Assignments for the electronic spectra are proposed. Conductivity data indicate that these derivatives are nonelectrolytes. Both ethylenediamine and [RSeO2 ]– behave as monodentate ligands
Osmium carbodithioato derivatives. Syntesis and spectroscopic studies
No full textSeveral new dithiocarbamate complexes of osmium(III) and osmium(II) have been synthetized and characterized by i. r. and electronic spectra, magnetic susceptibilities and conductivity measurements. The dithio ligands show a bidentate behaviour in all the complexes. From the electronic absorption spectra the values of the ligand field parameters were determined; the nephelauxetic parameter is indicative of a strong covalency in the metal-ligand bond as confirmed by the Dq values. All the complexes of osmium (III) and osmium(II) were octahedral, distorted owing to the presence of two molecules of coordinated water the metal(II) derivatives; the room temperature magnetic susceptibility values show that the complexes are of low-spin type: the osmium(III) derivatives have one unpaired electron, while the osmium (II) ones were diamagnetic
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