1,721,020 research outputs found
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
Mechanochemical cocrystal formation studied by in situ Raman spectroscopy.
Get PDFU ovom radu mehanokemijskom sintezom u suhim uvjetima i tekućinom potpomognutim mljevenjem dobiveni su kokristali nikotinamida s benzojevom, antranilnom ili salicilnom kiselinom. Kokristali s antranilnom i benzojevom kiselinom dosad nisu bili poznati u literaturi i okarakterizirani su uz pomoć difrakcije rendgenskih zraka na praškastim uzorcima i uz pomoć Ramanove spektroskopije. Kristalne strukture dosad nepoznatih kokristala određene su iz difrakcijskih podataka. In situ Ramanovom spektroskopijom praćene su sve reakcije, a istraţio se i utjecaj dodatka male količine primarnih alkohola na brzinu i tijek reakcije.In this thesis neat grinding and liquid-assisted grinding procedures for mechanochemical synthesis of cocrystals of nicotinamide with benzoic, anthranillic or salicylic acid were investigated. Obtained cocrystals of nicotinamide with benzoic or anthranillic acid were not previously known in the literature and were charachterized using powder X-ray diffraction and Raman spectroscopy. Crystal structures were solved using powder X-ray diffraction data. In situ Raman spectroscopy was used to gain insights into the course of the reaction including the influence of small quantities of added alcohols
Supramolecular recognition of nucleobases in the solid state
Get PDFZagrijavanjem fizičkih smjesa komplementarnih nukleobaza potaknuto je njihovo
supramolekulsko prepoznavanje u čvrstom stanju. Dobiven je dosad nepoznati 1:1 kokristal 9-
metilgvanina i 1-metilcitozina. Njegova je kristalna struktura riješena pomoću podataka
dobivenih difrakcijom rentgenskog zračenja na polikristalnom uzorku. Molekule 9-
metilgvanina i 1-metilcitozina povezane su Watson-Crickovim načinom povezivanja koje
uključuje tri međumolekulske vodikove veze. Ovi rezultati mogu biti značajni jer
predstavljaju alternativan put nastanka supramolekulskih struktura koje su bile preduvjet za
daljnju biološku evoluciju.Supramolecular recognition of complementary nucleobases was thermally induced in the solid
state. Novel 1:1 cocrystal between 9-methylguanine and 1-methylcytosine was obtained. The
crystal structure of new cocrystal was elucidated using laboratory powder X-ray diffraction.
Molecules of 9-methylguanine and 1-methylcytosine are held together by Watson-Crick
hydrogen bonding motif that includes three intermolecule hydrogen bonds. It is considered
that these findings could be relevant as they stress out an alternative route of occurance of
supramolecular structures that were prerequisite for biological evolution
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
Razvoj metoda za praćenje in situ mehanokemijske sinteze Ramanovom spektroskopijom i difrakcijom na praškastom uzorku
No full textMilling reactions are conducted in high-energy ball mills in a closed assembly comprising of
a milling jar, sample, and a milling media. So far, monitoring a reaction course of such
reactions required periodic disruption of the milling process and sampling for further ex situ
analysis. Thus, information obtained in that way might not reflect the true nature of milling
reactions. Recently introduced in situ approach based on synchrotron powder X-ray
diffraction and Raman spectroscopy for monitoring milling reactions have been superior to
the already established ex situ analysis. This thesis represents a further development of
methods for uninterrupted real-time and in situ monitoring of milling reactions. Here, a detail
description of experimental setup and data analysis is given, and developed methods were
used for studying solid-state synthesis of metal-organic frameworks ZIF-6 and ZIF-8,
Knoevenagel condensation between barbituric acid and vanillin, isotope-exchange reactions
between benzoic acid and deuterated water, 2-pyridone, or paracetamol, and finally,
competitive cocrystallization reactions between nicotinamide and benzoic, anthranilic, or
salicylic acid.Reakcije mljevenjem odvijaju se u specijaliziranim mlinovima unutar zatvorenih posuda u
kojima se nalaze reaktanti i kuglice. Praćenje takvih reakcija je zahtjevalo periodičko
zaustavljanje mljevenja i uzorkovanje reakcijske smjese za daljnu anlizu ex situ. Stoga,
informacije dobivene na ovaj način ne moraju nužno odgovarati stvarnim kemijskim i
fizikalnim procesima koji se odvijaju tijekom reakcije. Nedavno uvedene metode praćenja
reakcija mljevenja, temeljene na difrakciji na praškastom uzorku i Ramanovoj spektroskopiji
in situ, pokazale su se superiornim u usporedbi s dosad korištenim metodama ex situ. U ovoj
disertaciji prikazan je daljnji razvoj metoda za neprekidno praćenje reakcija mljevenja, te je
dan detaljan opis eksperimentalnog postava i obrade prikupljenih podataka. Razvijene
metode iskorištene su u proučavanju sinteze u čvrstom stanju metalo-organskih mreža ZIF-6 i
ZIF-8, Knoevenagelovoj kondenzaciji između barbiturne kiseline i vanilina, reakcijama
izmjene izotopa između benzojeve kiseline i deuterirane vode, 2-piridona ili paracetamola, i
kompetitivnim reakcijama kokristalizacije između nikotinamida i benzojeve, antranilne ili
salicilne kiseline
Investigation of mechanochemicalreactions by in situ Raman spectroscopy - contributions of physical and chemical factors
No full textU sklopu ove disertacije istražen je utjecaj eksperimentalnih parametara i molekulske strukture na mehanokemijsku reaktivnost. Na modelnoj reakciji jednostupanjske trimerizacije niklovog(II) dibenzoilmetanata sustavno je analiziran utjecaj frekvencije mljevenja, veličine i mase kuglice za mljevenje na kinetiku isključivo mehanički aktivirane transformacije. Uloga i učinak udarca kuglice ispitan je za proces kontinuiranog mljevenja u ukupnoj masi uzorka te na sloju praha, čime su povezane globalna i lokalna kinetika. Uspoređeni su reakcijski mehanizmi u kugličnom mlinu, gdje je dominatna mehanička sila, te u sustavu bez kuglica, odnosno u rezonancijsko-akustičnoj miješalici na modelu sinteze kalkonâ. Pored fizikalnih čimbenika, proučen je utjecaj elektronske strukture i aditiva na mehanosintezu iminâ te aza- Michaelovih adukata. Tim eksperimentima potvrđena je primjenjivost Hammettove korelacije, koncepta razvijenog za reakcije u otopini.As part of this doctoral thesis, the influence of experimental parameters and molecular structure on mechanochemical reactivity was investigated. Using the one-step trimerization of nickel(II) dibenzoylmethanate as a model system, the effects of milling frequency, ball size, and ball mass on the kinetics of a purely mechanically activated transformation were systematically analyzed. The role of ball impacts was examined both within the bulk and on the powder layer, thereby connecting global and local kinetics. Reaction mechanisms were compared between ball milling, where mechanical impact is the dominant force, and a system without milling balls, specifically a resonance acoustic mixer, using chalcone synthesis as a model reaction. In addition to physical factors, the influence of electronic structure and additives on the mechanosynthesis of imines and aza-Michael adducts was studied. These experiments confirmed the applicability of the Hammett correlation, a concept originally developed for solution-phase reactions
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