118,336 research outputs found
Comprehensibility of UML-B - A Series of Controlled Experiments
No full textThis paper summarises two controlled experiments conducted on a model that integrates the use of semi-formal notation, the Unified Modelling Language (UML) and a formal notation, B. The experiments assessed the comprehensibility of the model, namely UML-B. The first experiment compared the comprehensibility of a UML-B model and a B model. In the second experiment, the model was compared with an Event-B model, a new generation of B. The experiments assessed the ability of the model to present information and to promote problem domain understanding. The measurement focused on the efficiency in performing the comprehension tasks. The experiments employed a cross-over design and were conducted on third-year and masters students. The results suggest that the integration of semi-formal and formal notations expedites the subjects’ comprehension tasks with accuracy even with limited hours of training
Using ecological and field survey data to establish a national list of the wild bee pollinators of crops
No full textMM was funded by grant INIA-RTA2013-00139-C03-01 (MINECO and FEDER)Hutchinson, L.A., Oliver, T.H., Breeze, T.D., Bailes, E.J., Brünjes, L., Campbell, A.J., Erhardt, A., de Groot, G.A., Földesi, R., García, D., Goulson, D., Hainaut, H., Hambäck, P.A., Holzschuh, A., Jauker, F., Klatt, B.K., Klein, A.-M., Kleijn, D., Kovács-Hostyánszki, A., Krimmer, E., McKerchar, M., Miñarro, M., Phillips, B.B., Potts, S.G., Pufal, G., Radzevičiūtė, R., Roberts, S.P.M., Samnegård, U., Schulze, J., Shaw, R.F., Tscharntke, T., Vereecken, N.J., Westbury, D.B., Westphal, C., Wietzke, A., Woodcock, B.A., Garratt, M.P.D
Leptin and peroxisome proliferator activated receptor alpha: understanding their contribution towards normalising the programmed phenotype in the peripheral tissues of IUGR offspring
No full textIn a rat model of intrauterine growth restriction (IUGR) induced by maternal global undernutrition, adult offspring are obese with associated metabolic disturbances. These metabolic abnormalities are all augmented by feeding a high calorie postnatal diet and reversed by neonatal leptin treatment. Evidence is now accumulating which indicates that altered epigenetic regulation and gene expression may underpin the relationship between the early life environment and metabolic disturbances in adult life. Therefore, to determine the mechanism responsible for the alterations in energy balance in the IUGR rat, this study investigated the effect of maternal diet, neonatal leptin treatment and a postnatal high fat diet on the expression and DNA methylation of genes involved in energy balance in the liver and adipose tissue of adult offspring. These genes included the peroxisome proliferator activated receptors (PPARs) and their target genes; acyl-coA oxidase (AOX), carnitine palmitoyl transferase-1 (CPT-1) and lipoprotein lipase (LPL).Real time PCR indicated that the expression of several key genes involved in energy balance, including PPAR?, PPAR? and their target genes, was not altered by maternal diet or postnatal diet in the liver or adipose tissue of these offspring. However, in adipose tissue, neonatal leptin treatment resulted in an increase in the expression of most genes tested, including PPAR?, PPAR? and their target genes. The increased PPAR? and LPL would facilitate the uptake of fatty acids into the adipocyte, whilst the upregulation of PPAR? and its target genes AOX and CPT-1, not normally expressed in adipocytes, would direct fatty acids taken up towards the ?-oxidation pathway instead of storage. This would imply that the fat cell had transformed from a fat storing cell to a fat metabolising cell. Gene expression data therefore indicated that the phenotypic changes induced by neonatal leptin treatment, i.e. the reduced weight gain, could be due to increased expression of PPAR?, PPAR? and their target genes in adipose tissue: Furthermore, the effects of this are persistent, due to the specific period of leptin administration during neonatal development. There was, however, no evidence of altered DNA methylation in the promoter regions measured which could account for these persistent effects.To investigate mechanisms underlying the regulation of the PPAR? promoter by leptin, the rat PPAR? promoter was mapped, cloned and characterised. As part of this process, six alternatively spliced variants were identified; one from adipose tissue (P1), two from the liver (P2, P3), one from the heart (P4) and two from the kidney (P5, P6). These transcripts were found to differ in their 5’untranslated region due to tissue specific promoter usage and alternative transcription start sites. The liver and adipose specific promoters were cloned and characterised using a reporter gene strategy. They were shown to differ in their basal activity, response to known activators of transcription and to neonatal leptin treatment. The regulation of the PPAR? promoter by leptin was investigated and shown to function via a non-canonical mechanism requiring both signal transducer and activators of transcription (Stat3) and specificity protein-1 (Sp1), which act at a unique region of the liver specific P2 promoter. The adipose specific P1 promoter was shown to be unresponsive to leptin treatment. Furthermore, real time PCR with primers specific to the P1 and P2 PPAR? transcripts indicated that the increased PPAR? expression seen in leptin treated offspring was due to an increase in the P2 specific transcript, not the P1 transcript. This indicated that the neonatal leptin treatment facilitated a selective switch in promoter usage to increase the expression of PPAR? and its target genes in a tissue in which they are not normally expressed, thus inducing an altered metabolism within the adipocytes of these offspring
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
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
Fig. 4. – A in Mimusops coriacea (A. DC.) Miq. (Sapotaceae): nomenclature, distribution and ecology
No full textFig. 4. – A tree of Mimusops coriacea (A. DC.) Miq. preserved in the city of Masoala, Eastern Madagascar. [Photo: L. Gautier]Published as part of Laurent, Gautier, Nusbaume, Louis, Garratt, Rhéa, Randrianivo, Richard & Phillipson, Peter B., 2012, Mimusops coriacea (A. DC.) Miq. (Sapotaceae): nomenclature, distribution and ecology, pp. 148-151 in Candollea 67 (1) on page 151, DOI: 10.15553/c2012v671a16, http://zenodo.org/record/571014
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Structural and functional characterization of three enzymes with potential biotechnological use from the D-mannose/L-galactose biosynthetic pathway of L-ascorbic acid from Myrciaria dubia camu-camu
No full textMyrciaria dubia (Kunth) McVaugh, conhecida como camu-camu ou araçá dagua, é uma fruta nativa da Amazônia, caracterizada por seu alto teor de L-Ácido Ascórbico (Vitamina C ou AsA). Devido a esta propriedade, as enzimas que participam da biossíntese de AsA poderiam ter potenciais aplicações biotecnológicos para a produção artificial de AsA. No entanto, a biologia estrutural das enzimas envolvidas tem sido bem pouco explorada. Aqui, descrevemos as propriedades biofísicas, funcionais e estruturais para três enzimas da via D-manose/L-galactose (Smirnoff & Wheeler). As enzimas foram purificadas por cromatografia de afinidade e exclusão molecular. GDP-D-manose-3,5-epimerase (MdGME), que catalisa uma dupla epímerização da GDP-manose para produzir GDP-L-galactose e GDP-L-gulose, provou ser um dímero em solução, suas estruturas cristalográficas foram resolvidas complexadas, sua forma apo (2,5 Å, ligada a NAD+) e holo (1.25 Å ligada a NAD+/substrato/produto). A L-galactose desidrogenase (MdGDH) e L-galactono-1,4lactona desidrogenase (MdGalDH) provaram ser monoméricas em solução. MdGDH apresentou uma atividade catalítica com um Km de 0,128 mM e pH ótimo de 7. Demostramos que a inibição por AsA em MdGDH é devido a mudanças no pH e não necessariamente por uma inibição competitiva pelo sítio ativo como foi reportada para a enzima homóloga de espinafre (SoGDH). A estrutura cristalográfica de SoGDH foi resolvida a 1,4 e 1,75 Å em suas formas apo e holo (ligado a NAD+), respectivamente. Finalmente a MdGalDH apresentou uma atividade catalítica com um Km de 0,044 mM e pH ótimo de 8 e apresentou uma inibição pelo próprio substrato. A estrutura cristalográfica foi resolvida a 2,1 Å. O presente trabalho contribui para uma compreensão mais amplo das relações estrutura-função das enzimas envolvidas na síntese da vitamina C.Myrciaria dubia (Kunth) McVaugh, known as camu-camu or aracá dagua, is a fruit native to the Amazon, characterized by its high content of L-Ascorbic Acid (Vitamin C or AsA). Due to this property, the enzymes that participate in the biosynthesis of AsA could have potential biotechnological applications for the artificial production of AsA. However, the structural biology of the enzymes involved has been poorly explored. Here, we describe the biophysical, functional, and structural properties for three enzymes of the D-mannose/L-galactose pathway (Smirnoff & Wheeler). The enzymes are purified by affinity chromatography and molecular exclusion. GDP-D-mannose-3´,5´-epimerase (MdGME), which catalyzes a double epimerization of GDP-mannose to produce GDP-L-galactose and GDP-L-gulose, proved to be a dimer in solution, its crystallographic structure was solved, in both its apo (2.5 Å, bound to NAD+) and holo (1.25 Å bound to NAD+/substrate/product) form. L-galactose dehydrogenase (MdGDH) and L-galactono-1,4-lactone dehydrogenase (MdGalDH) proved to be monomeric in solution. MdGDH showed a catalytic activity with a Km of 0.128 mM and an optimal pH of 7. We show that inhibition by AsA in MdGDH is due to pH changes and is not necessarily due to a competitive inhibition at its active site as reported for the homologous enzyme of spinafre (SoGDH). The crystallographic structure of SoGDH was solved at 1.4 and 1.75Å in its apo and holo (NAD+-bound) forms, respectively. Finally, MdGalDH showed a catalytic activity with a Km of 0.044 mM and an optimal pH of 8 and was inhibited by its own substrate. The crystallographic structure was solved to 2.1 Å. The present work contributed to a broader understanding of the structure-function relationships of enzymes involved in the synthesis of vitamin C
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