Social inertia in collaboration networks

This work is a study of the properties of collaboration networks employing the formalism of weighted graphs to represent their one-mode projection. The weight of the edges is directly the number of times that a partnership has been repeated. This representation allows us to define the concept of "social inertia" that measures the tendency of authors to keep on collaborating with previous partners. We use a collection of empirical datasets to analyze several aspects of the social inertia: 1) its probability distribution, 2) its correlation with other properties, and 3) the correlations of the inertia between neighbors in the network. We also contrast these empirical results with the predictions of a recently proposed theoretical model for the growth of collaboration networks.Comment: 7 pages, 5 figure

Purification and Characterization of a Gamma-Like DNA-Polymerase From \u3ci\u3eChenopodium album\u3c/i\u3e L.

A DNA polymerase activity from mitochondria of the dicotyledonous angiosperm Chenopodium album L. was purified almost 9000 fold by successive column chromatography steps on DEAE cellulose, heparin agarose and ssDNA cellulose. The enzyme was characterized as a gamma-class polymerase, based on its resistance to inhibitors of the nuclear DNA polymerase alpha and its preference for poly(rA).(dT)12-18 over activated DNA in vitro. The molecular weight was estimated to be 80,000 - 90,000. A 3\u27 to 5\u27 exonuclease activity was found to be tightly associated with the DNA polymerase activity through all purification steps. This is the first report of an association between a DNA polymerase and an exonuclease activity in plant mitochondria

Enhanced retinal image registration accuracy using expectation maximisation and variable bin-sized mutual information

While retinal images (RI) assist in the diagnosis of various eye conditions and diseases such as glaucoma and diabetic retinopathy, their innate features including low contrast homogeneous and nonuniformly illuminated regions, present a particular challenge for retinal image registration (RIR). Recently, the hybrid similarity measure, Expectation Maximization for Principal Component Analysis with Mutual Information (EMPCA-MI) has been proposed for RIR. This paper investigates incorporating various fixed and adaptive bin size selection strategies to estimate the probability distribution in the mutual information (MI) stage of EMPCA-MI, and analyses their corresponding effect upon RIR performance. Experimental results using a clinical mono-modal RI dataset confirms that adaptive bin size selection consistently provides both lower RIR errors and superior robustness compared to the empirically determined fixed bin sizes

Multimodal retinal image registration using a fast principal component analysis hybrid-based similarity measure

Multimodal retinal images (RI) are extensively used for analysing various eye diseases and conditions such as myopia and diabetic retinopathy. The incorporation of either two or more RI modalities provides complementary structure information in the presence of non-uniform illumination and low-contrast homogeneous regions. It also presents significant challenges for retinal image registration (RIR). This paper investigates how the Expectation Maximization for Principal Component Analysis with Mutual Information (EMPCA-MI) algorithm can effectively achieve multimodal RIR. This iterative hybrid-based similarity measure combines spatial features with mutual information to provide enhanced registration without recourse to either segmentation or feature extraction. Experimental results for clinical multimodal RI datasets comprising colour fundus and scanning laser ophthalmoscope images confirm EMPCA-MI is able to consistently afford superior numerical and qualitative registration performance compared with existing RIR techniques, such as the bifurcation structures method

Crystal structure of (η4-norborna-2,5-dien)-(1,2-bis((R,R)-2,5-bis-(methoxymethyl)phospholanyl)benzene)rhodium(I) tetrafluoroborate, [Rh(C22H36O4P2)(C7H8)](BF4)

C29H44BF4O4P2Rh, monoclinic, P21 (no. 4), a= 10.119(2) Å, 6= 14.125(3) Å, c = 11.542(2) Å, β = 106.87(3)°, V = 1578.7 Å3, Z= 2, Rgt(F) = 0.034, wRref(F2) = 0.090, T = 200 K

Interfaces for science: Conceptualizing an interactive graphical interface

6,849.32 new research journal articles are published every day. The exponential growth of Scientific Knowledge Objects (SKOs) on the Web, makes searches time-consuming. Access to the right and relevant SKOs is vital for research, which calls for several topics, including the visualization of science dynamics. We present an interface model aimed to represent of the relations that emerge in the science social space dynamics, namely through the visualization and navigation of the relational structures between researchers, SKOs, knowledge domains, subdomains, and topics. This interface considers the relationship between the researcher who reads and shares the relevant articles and the researcher who wants to find the most relevant SKOs within a subject matter. This article presents the first iteration of the conceptualization process of the interface layout, its interactivity and visualization structures. It is essential to consider the hierarchical and relational structures/algorithms to represent the science social space dynamics. These structures are not being used as analysis tools, because it is not objective to show the linkage properties of these relationships. Instead, they are used as a means of representing, navigating and exploring these relationships. To sum up, this article provides a framework and fundamental guidelines for an interface layout that explores the social science space dynamics between the researcher who seeks relevant SKOs and the researchers who read and share them.This work has been supported by COMPETE: POCI-01-0145-FEDER- 007043 and FCT - Fundação para a Ciência e Tecnologia within the Project Scope: (UID/CEC/00319/2013) and the Project IViSSEM: ref: POCI-010145-FEDER-28284

Population Structure of <i>Mycosphaerella graminicola</i> and Location of Genes for Resistance to the Pathogen: Recent Advances in Argentina

Leaf blotch of wheat (Septoria tritici Rob. ex Desm., teleomorph Mycosphaerella graminicola (Fückel) Schr¨ot. in Cohn) causes significant losses in wheat. During the last decades studies about the genetic variability of the pathogen and location of the resistance have been intensive around the world. The knowledge about the genetic variation of M. graminicola is very important because it could allow us to determine which genotypes predominate within a geographic area. It also can be used to evaluate the germplasm resistance of wheat cultivars with isolates with high genetic differences. In addition, the knowledge of the genes conditioning resistance in different genotypes allows getting precise combination in new germplasm. The incorporation of the known genes in new cultivars could contribute to broadening the resistance to the pathogen. A paper about genetic variability of the pathogen and location of the resistance, with special emphasis in the work carried out in Argentina, is presented.Facultad de Ciencias Agrarias y Forestale

Lippen-Kiefer-Gaumen-Spalten: Individuelle Analyse der Lippenspalte durch 3-D-Lasertopometrie

Zusammenfassung: Hintergrund: Mit Gipsmodellen und Fotografien ist die dreidimensionale Analyse einer Lippen-Kiefer-Gaumen-Spalte meist nur unzureichend möglich. Ziel der vorliegenden Studie war es daher, die 3-D-Lasertopometrie auf ihre Anwendbarkeit zur dreidimensionalen Weichgewebserfassung bei Patienten mit Lippen-Kiefer-Gaumen-Spalten zu testen. Patienten und Methode: Bei 20 Patienten (3-35 Jahre), die eine einseitige, nicht operierte Lippen-, Lippen-Kiefer- oder Lippen-Kiefer-Gaumen-Spalte aufwiesen, wurde mit einem 3-D-Laserscanner die Gesichtsoberfläche prä- und postoperativ dreidimensional erfasst. Die dabei erzeugten digitalen Datensätze wurden in einer virtuellen Umgebung metrisch analysiert und anhand von Quotienten größenunabhängig wiedergegeben. Sie dienten der Auswahl der Operationstechnik und der Beurteilung des Operationsergebnisses. Ergebnisse: Mit dem 3-D-Laserscanner wurden 3-D-Oberflächen guter Qualität erstellt, die sich im Millimeterbereich ausmessen ließen. Die dreidimensionale Spaltmorphologie konnte in den Datensätzen reproduzierbar mit Landmarks versehen und vermessen werden. Auch die postoperative Symmetrie ließ sich so kontrollieren und objektivieren. Als nachteilig erwiesen sich die relativ lange Messzeit und die Notwendigkeit zur Kombination mehrerer Ansichten. Schlussfolgerung: Das vorgestellte 3-D-Laserverfahren ermöglicht eine präzise dreidimensionale Weichteilanalyse der Lippen- und Nasenregion bei Spaltpatienten. Es eignet sich jedoch nur bedingt für lebhafte Säuglinge und unkooperative Patiente