356 research outputs found
Deterministic Linear Time Constrained Triangulation using Simplified Earcut
Triangulation algorithms that conform to a set of non-intersecting input segments typically proceed in an incremental fashion, by inserting points first, and then segments. Inserting a segment amounts to: (1) deleting all the triangles it intersects; (2) filling the so generated hole with two polygons that have the wanted segment as shared edge; (3) triangulate each polygon separately. In this paper we prove that these polygons are such that all their convex vertices but two can be used to form triangles in an earcut fashion, without the need to check whether other polygon points are located within each ear. The fact that any simple polygon contains at least three convex vertices guarantees the existence of a valid ear to cut, ensuring convergence. Not only this translates to an optimal deterministic linear time triangulation algorithm, but such algorithm is also trivial to implement. We formally prove the correctness of our approach, also validating it in practical applications and comparing it with prior art
Improving global influenza surveillance: trends of A(H5N1) virus in Africa and Asia
<p>Abstract</p> <p>Background</p> <p>Highly pathogenic avian influenza A(H5N1) viruses are an important health problem in many Asian and African countries. The current increase in human cases demonstrates that influenza A(H5N1) is still a significant global pandemic threat. Many health organizations have recognized the need for new strategies to improve influenza global surveillance. Specifically, the World Health Organization through the global technical consultation for influenza surveillance have called for a detailed picture of the current limitations, especially at the nation level, to evaluate, standardize and strength reporting systems. The main goal of our study is to demonstrate the value of genetic surveillance as part of a strategic surveillance plan. As a proof of concept, we evaluated the current situation of influenza A(H5N1) in Asian and Africa.</p> <p>Results</p> <p>Our analysis revealed a power-law distribution in the number of sequences of A(H5N1) viruses analyzed and/or reported to influenza surveillance networks. The majority of the Asian and African countries at great risk of A(H5N1) infections have very few (approximately three orders of magnitude) sequenced A(H5N1) viruses (e.g. hemagglutinin genes). This suggests that countries under pandemic alert for avian influenza A(H5N1) have very limited participation (e.g. data generation, genetic analysis and data share) in avian influenza A(H5N1) surveillance. More important, this study demonstrates the usefulness of influenza genetic surveillance to detect emerging pandemic threat viruses.</p> <p>Conclusions</p> <p>Our study reveals that some countries suffering from human cases of avian influenza have limited participation (e.g. genetic surveillance or data share) with global surveillance networks. Also, we demonstrate that the implementation of genetic surveillance programs could increase and strengthen worldwide epidemic and pandemic preparedness. We hope that this work promotes new discussions between policy makers and health surveillance organizations to improve current methodologies and regulations.</p
Nuclear and chloroplast microsatellite diversity in Phaseolus vulgaris L. from Sardinia (Italy).
Studies of the level and the structure of
the genetic diversity of local varieties of Phaseolus
vulgaris are of fundamental importance, both for the
management of genetic resources and to improve our understanding of the pathways of dissemination and
the evolution of this species in Europe. We have here
characterized 73 local bean populations from Sardinia
(Italy) using seed traits and molecular markers
(phaseolins, nuSSRs and cpSSRs). American landraces
and commercial varieties were also included for
comparison. We see that: (a) the Sardinian material is
distinct from the commercial varieties considered; (b)
the variation in the seed traits is high and it mostly
occurs among populations (95%); (c) compared to the
American sample and the commercial varieties, the
Sardinian collection has a low level of diversity; (d)
the majority ([95%) of the Sardinian individuals
belong to the Andean gene pool; (e) the Sardinian
material shows a strong genetic structure, both for
cpSSRs and nuSSRs; (f) the nuSSRs and cpSSRs
concur in differentiating between gene pools, but a
lack of congruence between nuclear and chloroplast
has been observed within gene pools; and (g) there
are three putative hybrids between the Andean and
Mesoamerican gene pools. Despite the relatively low
level of diversity, which is probably due to a strong
founder effect, the Sardinian landraces are worth
being conserved and studied further because of their
distinctiveness and because hybridization within and
between the gene pools could generate variation that
will be useful for breeding
A Robust Implicit Optimal Order Formula for Direct Integration of Second Order Orbital Problems
In this paper, a robust implicit formula of optimal order for direct integration of general second order orbital problems of ordinary differential equations (ODEs) is proposed. This method is considered capable avoiding the computational burden and wastage in computer time in connection with the method of reduction to first order systems. The integration algorithms and analysis of the basic properties are based on the adoption of Taylor’s expansion and Dahlquist stability model test. The resultant integration formula is of order ten and it is zero-stable, consistent, convergent and symmetric. The numerical implementation of the method to orbital and two-body problems demonstrates increased accuracy with the same computational effort on comparison with similar second order formulas. Keywords: Optimal-order, Zero-stability, Convergence, Consistent, IVPs, Predictor-corrector, Error constant, Symmetric
Biological Control Efforts of Water hyacinth (Eichhornia crassipes (Mart.) Solm) on Kainji Lake, Nigeria
Biological control of water hyacinth (Eichhornia crassipes (Mart.) Solm) was monitored on Kainji Lake between 1995 and 1999. The two most important host specific natural enemies of water hyacinth (Neochetina eichhorniae and N. bruchi) were used and impacts of the weevils on water hyacinth were monitored on tri-monthly basis. The manual control initiated by the National Institute for Freshwater Fisheries Research (NIFFR) encouraged the fishermen to physically remove water hyacinth from their shores and open water. The lake hydrology, most especially during the drawdown period when the water volume is reduced tremendously, allows water hyacinth plants to be stranded by the bank of the lake thereby leading to massive destruction of the weed population and consequently the weevils population stability. The floristic composition of macrophyte intimately mixed with the water hyacinth was also monitored during the low and high water regimes. Among the prominent plant species found with water hyacinth included Echinochloa stagnina, Mimosa pigra, Polygonium senegalensis Polygonium lanigarium. Sesbania dalzelli, and Vosia cuspidata were found competing with the much favoured Echinochloa spp which serves as forage to livestock around the lake; However, no incidence of weevil attack was observed on any of the vegetation mixed with water hyacinth. Keywords: Biocontol, Kainji Lake, Water hyacinth, Weevils
El Nuevo Orden Internacional de la Información y la Comunicación
Artículo sobre el Nuevo Orden Internacional de la Información y la Comunicación; se repasan sus antecedentes en la Organización de las Naciones Unidas para la Educación, la Ciencia y la Cultura (UNESCO) a principios de los setenta, en donde se discutía la promoción del establecimiento de políticas nacionales de comunicación. Se habla sobre la evolución del proyecto, su implementación en América Latina, los logros que alcanzó, sus detractores y la necesidad de una reformulación a partir de las nuevas tecnologías de la información y la comunicación
A NLP Pipeline for the Automatic Extraction of a Complete Microorganism’s Picture from Microbiological Notes
The Italian “Istituto Superiore di Sanità” (ISS) identifies hospital-acquired infections (HAIs) as the most frequent and serious complications in healthcare. HAIs constitute a real health emergency and, therefore, require decisive action from both local and national health organizations. Information about the causative microorganisms of HAIs is obtained from the results of microbiological cultures of specimens collected from infected body sites, but microorganisms’ names are sometimes reported only in the notes field of the culture reports. The objective of our work was to build a NLP-based pipeline for the automatic information extraction from the notes of microbiological culture reports. We analyzed a sample composed of 499 texts of notes extracted from 1 month of anonymized laboratory referral. First, our system filtered texts in order to remove nonmeaningful sentences. Thereafter, it correctly extracted all the microorganisms’ names according to the expert’s labels and linked them to a set of very important metadata such as the translations into national/international vocabularies and standard definitions. As the major result of our pipeline, the system extracts a complete picture of the microorganism
Tagging the Signatures of Domestication in Common Bean (Phaseolus vulgaris) by Means of Pooled DNA Samples
-Background and Aims: The main aim of this study was to use an amplified fragment length polymorphism (AFLP)-based, large-scale screening of the whole genome of Phaseolus vulgaris to determine the effects of selec- tion on the structure of the genetic diversity in wild and domesticated populations.
-Methods: Using pooled DNA samples, seven each of wild and domesticated populations of P. vulgaris were studied using 2506 AFLP markers (on average, one every 250 kb). About 10% of the markers were also analysed on indi-
-Key Results: The most important outcome is that a large fraction of the genome of the common bean (16 %; P, 0.01) appears to have been subjected to effects of selection during domestication. Markers obtained in indivi-
vidual genotypes and were used to infer allelic frequencies empirically from bulk data. In both data sets, tests were made to determine the departure from neutral expectation for each marker using an FST-based method.
dual genotypes were also mapped and classified according to their proximities to known genes and quantitative trait loci (QTLs) of the domestication syndrome. Most of the markers that were found to be potentially under the effects of selection were located in the proximity of previously mapped genes and QTLs related to the domestication syndrome.
- Conclusions: Overall, the results indicate that in P. vulgaris a large portion of the genome appears to have been subjected to the effects of selection, probably because of linkage to the loci selected during domestication. As most
of the markers that are under the effects of selection are linked to known loci related to the domestication syndrome, it is concluded that population genomics approaches are very efficient in detecting QTLs. A method based on bulk DNA samples is presented that is effective in pre-screening for a large number of markers to determine selection signatures
Repeated Sprint Ability in Young Basketball Players (Part 2): The Chronic Effects of Multidirection and of One Change of Direction Are Comparable in Terms of Physiological and Performance Responses
The aim of this study was to examine the effects of a 5-week training program, consisting of repeated 30-m sprints, on two repeated sprint ability (RSA) test formats: one with one change of direction (RSA) and the other with multiple changes of direction (RSM). Thirty-six young male and female basketball players (age 16.1 ± 0.9 years), divided into two experimental groups, were tested for RSA, RSM, squat jump, counter-movement jump, and the Yo-Yo Intermittent Recovery-Level-1 (Yo-Yo IR1) test, before and after a 4-week training program and 1 week of tapering. One group performed 30-m sprints with one change of direction (RSA group, RSAG), whereas the other group performed multidirectional 30-m sprints (RSM group, RSMG). Both groups improved in all scores in the post-intervention measurements (P < 0.05), except for the fatigue index in the RSM test. However, when comparing the two groups, similar effects were found for almost all parameters of the tests applied, except for RPE in the RSA test, which had a greater decrease in the RSAG (from 8.7 to 5.9) than in the RSMG (from 8.5 to 6.6, P = 0.021). We can conclude that repeated 30-m sprints, either with one change of direction or multidirectional, induce similar physiological and performance responses in young basketball players, but have a different psycho-physiological impact
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