804 research outputs found
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Letter to the editor: Reply to J. J. Child, Crim. L.R. 2010, 12, 924-932
No full textResponds to J.J. Child's article in this issue criticising the conclusions reach by the author in his article "The conflict between the Serious Crime Act 2007 and section 1(4)(b) Criminal Attempts Act 1981 - a missed repeal?", (Crim. L.R. 2010, 6, 483-488)
Some Comments on the Question Whether Co-occurrence Data Should Be Normalized
No full textIn a recent paper in the Journal of the American Society for Information Science and Technology, Leydesdorff and Vaughan assert that raw cocitation data should be analyzed directly, without first applying a normalization like the Pearson correlation. In this report, it is argued that there is nothing wrong with the widely adopted practice of normalizing cocitation data. One of the arguments put forward by Leydesdorff and Vaughan turns out to depend crucially on incorrect multidimensional scaling maps that are due to an error in the PROXSCAL program in SPSS.Multidimensional scaling;Author cocitation analysis;Co-occurrence data;Normalization;PROXSCAL;Pearson correlation
Some Comments on the Question Whether Co-Occurrence Data Should Be Normalized
No full textIn a recent article in JASIST, L. Leydesdorff and L. Vaughan (2006) asserted that raw cocitation data should be analyzed directly, without first applying a normalization such as the Pearson correlation. In this communication, it is argued that there is nothing wrong with the widely adopted practice of normalizing cocitation data. One of the arguments put forward by Leydesdorff and Vaughan turns out to depend crucially on incorrect multidimensional scaling maps that are due to an error in the PROXSCAL program in SPSS.multidimensional scaling;PROXSCAL;Pearson correlation;author cocitation analysis;co-occurrence data;normalization
I. Nota betreffende de bemaling van de Drentsche hoofdvaart, opgemaakt door den ingenieur van den Rijkswaterstaat dr. L.R. Wentholt: II. Nota over het proefheien van houten en ijzeren damwand te Linne, opgemaakt door den ingenieur van den Rijkswaterstaat F. Volker
No full textEisen waaraan gemalen moeten voldoen, beschrijving van de soorten gemalen, aandrijving, ontwerp en exploitatie. Prototyoe proef met ijzeren en houten damwanden bij de sluis te Linne
Neural crest motility and integrin regulation are distinct in cranial and trunk populations
No full textAbstractThe neural crest is a transient cell population that travels long distances through the embryo to form a wide range of derivatives. The extensive migration of the neural crest is highly unusual and incompletely understood. We examined the ability of neural crest cells (NCCs) to migrate under different conditions in vitro. Unlike most motile cell types, avian NCCs migrate efficiently on a wide range of fibronectin concentrations. Strikingly, the migration of NCCs on laminin depends on the axial level from which the crest is derived. On high concentrations of laminin, cranial NCCs migrate at approximately twice the rate of trunk NCCs and show greater persistence, a higher percentage of migratory cells, and a less organized cytoskeleton. The difference in migration between cranial and trunk neural crest is not due to transcriptional differences in integrin mRNA, but rather to differences in posttranslational regulation. Overexpression of a single integrin is sufficient to significantly slow the migration velocity of cranial neural crest cultured on high laminin densities. These results demonstrate that neural crest cells accommodate a wide range of ECM concentrations in vitro and suggest that differences in integrin regulation along the anterior–posterior axis may contribute to differences in neural crest migration and cell fate
Erratum to “Neural crest motility and integrin regulation are distinct in cranial and trunk populations” [Dev. Biol. 259 (2003) 288–302]
No full textEnkele nauwkeurigheidsaspekten van de digitale signaalverwerking en mogelijkheden tot signaal-ruisverbetering bij een troposfeer aftastende F.M.-C.W.radar
No full textEen uitgebreide analyse van de meetresultaten van de troposfeerradar is zo tijdrovend, dat deze niet tijdens de meting plaats kan vinden. Om toch een indruk te krijgen van wat gemeten wordt, is de zogenaamde monitor ontwikkeld. Deze moet de meetresultaten binnen de 1 sec. verwerken. Hierbij is de nauwkeurigheid van iets minder belang. Deze signaalverwerking wordt met behulp van een rekenmachine uitgevoerd en het fast fourier transform algoritme is hiervan een belangrijk onderdeel. De nauwkeurigheid van dit algoritme in vaste komma en "block-floating point"-uitvoering is onderzocht in relatie tot de verwachte ingangssignalen. Daarnaast is aandacht besteed aan de mogelijkheden tot verbetering van signaal-ruisverhouding, rekening houdend met de beperkingen opgelegd door eigenschappen van het meetsysteem en de troposfeer.Applied SciencesElectrotechniekTransmissie van Informati
Digitale signaalverwerking van de F.M.-C.W.radar met behulp van een 21 MX computer
No full textBij het dakproject bestaat de behoefte aan een snelle signaalverwerking teneinde een quasi momentane afbeelding van het brekingsindexverloop in de troposfeer te verwezenlijken. Deze "monitorfunctie" wordt gerealiseerd m.b.v. een microgeprogrammeerde Fast Fourier Transform algoritme in "block-floating point" uitvoering. Als eis wordt hierbij gesteld dat de signaalverwerking binnen 1 sec. plaatsvindt. In het frequentiedomein kunnen datavensters worden toegepast die weinig rekentijd vergen. Deze datavensters verbeteren de resolutie. Ook wordt ingegaan op de te volgen procedures bij microprogrammering op een 21 MX computer van Hewlett Packard.Electrical Engineering, Mathematics and Computer ScienceTransmissie van Informati
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