Search results for " pattern"
showing 10 items of 2245 documents
Network dynamics of eukaryotic LTR retroelements beyond phylogenetic trees
2009
Abstract Background Sequencing projects have allowed diverse retroviruses and LTR retrotransposons from different eukaryotic organisms to be characterized. It is known that retroviruses and other retro-transcribing viruses evolve from LTR retrotransposons and that this whole system clusters into five families: Ty3/Gypsy, Retroviridae, Ty1/Copia, Bel/Pao and Caulimoviridae. Phylogenetic analyses usually show that these split into multiple distinct lineages but what is yet to be understood is how deep evolution occurred in this system. Results We combined phylogenetic and graph analyses to investigate the history of LTR retroelements both as a tree and as a network. We used 268 non-redundant …
optomotor-blind suppresses instability at the A/P compartment boundary of the Drosophila wing.
2008
Formation and function of the A/P compartment boundary of the Drosophila wing have been studied intensely. The boundary prevents mingling of A and P cells, is characterized by an expression discontinuity of several genes like engrailed, Cubitus interruptus, hedgehog and decapentaplegic and is essential for patterning the wing. Compared with segmental or compartmental boundaries in several other systems which generally manifest as folds or clefts, the wing A/P boundary is morphologically inconspicuous in both the larval and adult stage. We show here that the Drosophila wing A/P boundary, too, is susceptible to fold and cleft formation and that these processes are suppressed by the T-box tran…
A Phylogenetic Analysis of Human Syntenies Revealed by Chromosome Painting in Euarchontoglires Orders
2010
To search for cytogenetic signatures that can help to clarify evolutionary affinities among the five orders within the Euarchontoglires clade, we focused on associations of conserved syntenic blocks that have been accumulated in the karyotypes of Primates (Strepsirhini and Haplorhini), five families of Rodentia, Scandentia (Tupaia belangeri), Dermoptera (Galeopterus variegatus) and Lagomorpha (Oryctolagus cuniculus). We examined available chromosome painting data to identify conserved chromosomes and chromosomal segments, and syntenic associations likely to have characterized the ancestral eutherian karyotype. The data set includes 161 characters that have been subjected to a concatenated a…
Estimation of Purkinje trees from electro-anatomical mapping of the left ventricle using minimal cost geodesics
2015
The electrical activation of the heart is a complex physiological process that is essential for the understanding of several cardiac dysfunctions, such as ventricular tachycardia (VT). Nowadays, patient-specific activation times on ventricular chambers can be estimated from electro-anatomical maps, providing crucial information to clinicians for guiding cardiac radio-frequency ablation treatment. However, some relevant electrical pathways such as those of the Purkinje system are very difficult to interpret from these maps due to sparsity of data and the limited spatial resolution of the system. We present here a novel method to estimate these fast electrical pathways from the local activati…
Exploratory spatial data analysis of the distribution of regional per capita GDP in Europe, 1980-1995
2000
The aim of this paper is to study the dynamics of European regional per capita product over time and space. This purpose is achieved by using the recently developed methods of Exploratory Spatial Data Analysis. Using a sample of European regions over the 1980-1995 period, we find strong evidence of global and local spatial autocorrelation in per capita GDP throughout the period. The detection of clusters of high and low per capita products during the period is an indication of the persistence of spatial disparities between European regions. This analysis is finally refined by the investigation of the spatial pattern of regional growth. Key words:exploratory spatial data analysis; distributi…
The influence of geography on the spatial agglomeration of production in the European Union
2012
Abstract We investigate the relative impact of geographic features on the location of production in the European Union. Specifically, we attempt to quantify how much of the spatial pattern of GDP can be attributed to exogenous first-nature elements alone and how much can be derived from endogenous second-nature factors. In order to disentangle both effects empirically, we control for second-nature factors. A method based on the decomposition of the per capita GDP variance is applied to a panel of 1,171 European NUTS 3 regions for 2006. We demonstrate that variable and model misspecifications may bias results unless proper allowance is made for spatial autocorrelation and spatial heterogenei…
Downy-oak woods of Italy: phytogeographical remarks on a controversial taxonomic and ecologic issue
2014
The importance of downy oak as an integral component of the "submediterranean" woods has been underscored by many studies. Nevertheless, terms like "submediterranean" and "downy oak" are some of the most poorly understood concepts in European phytogeographic and taxonomic research. Downy oak is well known to be a problematic taxon. The name "Quercus pubescens" (= Q. humilis) combines populations characterized by increasing phenotypic and genomic polymorphisms along north-south gradients, which is explained as the result of a "founder effect" produced by a relatively fast post-glacial re-colonization of the northern areas through rare long-distance dispersal events. On the other hand, polymo…
The Cognitive Demand of a Gifted Student’s Answers to Geometric Pattern Problems
2018
Mathematically gifted students require specific teaching methodologies to foster their interest in mathematics and their engagement in solving problems. Geometric pattern problems are an interesting context in which to introduce algebra to those students. We present the case of a nine-year-old student engaged in a teaching unit based on geometric pattern problems that was aimed at helping him start learning algebra, equations, and algebra word problems. To analyze and assess the cognitive effort the student made to solve the problems, we used a particularization to this context of the cognitive demand model. We analyzed answers typical of the different kinds of problems posed throughout the…
Dietary Patterns and Cognitive Decline: key features for prevention
2019
The decline in cognitive function is generally the result of the complex interaction of several factors. First of all, age, but also demographic, educational, genetic, socio-economic, and environmental determinants, including nutrition. Cognitive decline and dementia prevalence are increasing, and they are projected to continue increasing in the next decades due to the aging of the world population. Currently, there are no effective pharmacological treatments for these devastating and disabling conditions, which emphasize the key role of preventive strategies. There is compelling evidence of the role of diet and lifestyle on cognitive function. Therefore, dietary/ nutritional approaches th…
Mid-career work patterns and physical and mental functioning at age 60-64: evidence from the 1946 British birth cohort.
2016
Background: Previous studies of the associations between unemployment and health have primarily focused on mental health and long-term associations have not often been explored. This study investigated if discontinuous employment in mid-career was related to self-reported physical and mental functioning at age 60–64 years. Methods: Data come from the Medical Research Council National Survey of Health and Development, a British cohort that has been followed-up since birth in 1946. A total of 2061 study members had data available on mid-career employment patterns and physical and mental functioning assessed using the Short Form 36 questionnaire at age 60–64. Employment patterns in mid-career …