2,612 research outputs found

    Black and Minority Ethnic Trainees' Experiences of Physical Education Initial Teacher Training: Report to the Training and Development Agency

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    Snake mitochondrial genomes: phylogenetic relationships and implications of extended taxon sampling for interpretations of mitogenomic evolution

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    <p>Abstract</p> <p>Background</p> <p>Snake mitochondrial genomes are of great interest in understanding mitogenomic evolution because of gene duplications and rearrangements and the fast evolutionary rate of their genes compared to other vertebrates. Mitochondrial gene sequences have also played an important role in attempts to resolve the contentious phylogenetic relationships of especially the early divergences among alethinophidian snakes. Two recent innovative studies found dramatic gene- and branch-specific relative acceleration in snake protein-coding gene evolution, particularly along internal branches leading to Serpentes and Alethinophidia. It has been hypothesized that some of these rate shifts are temporally (and possibly causally) associated with control region duplication and/or major changes in ecology and anatomy.</p> <p>Results</p> <p>The near-complete mitochondrial (mt) genomes of three henophidian snakes were sequenced: <it>Anilius scytale</it>, <it>Rhinophis philippinus</it>, and <it>Charina trivirgata</it>. All three genomes share a duplicated control region and translocated tRNA<sup>LEU</sup>, derived features found in all alethinophidian snakes studied to date. The new sequence data were aligned with mt genome data for 21 other species of snakes and used in phylogenetic analyses. Phylogenetic results agreed with many other studies in recovering several robust clades, including Colubroidea, Caenophidia, and Cylindrophiidae+Uropeltidae. Nodes within Henophidia that have been difficult to resolve robustly in previous analyses remained uncompellingly resolved here. Comparisons of relative rates of evolution of rRNA vs. protein-coding genes were conducted by estimating branch lengths across the tree. Our expanded sampling revealed dramatic acceleration along the branch leading to Typhlopidae, particularly long rRNA terminal branches within Scolecophidia, and that most of the dramatic acceleration in protein-coding gene rate along Serpentes and Alethinophidia branches occurred before <it>Anilius </it>diverged from other alethinophidians.</p> <p>Conclusions</p> <p>Mitochondrial gene sequence data alone may not be able to robustly resolve basal divergences among alethinophidian snakes. Taxon sampling plays an important role in identifying mitogenomic evolutionary events within snakes, and in testing hypotheses explaining their origin. Dramatic rate shifts in mitogenomic evolution occur within Scolecophidia as well as Alethinophidia, thus falsifying the hypothesis that these shifts in snakes are associated exclusively with evolution of a non-burrowing lifestyle, macrostomatan feeding ecology and/or duplication of the control region, both restricted to alethinophidians among living snakes.</p

    Train Positioning Using Video Odometry

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    Reliable Data Systems have developed a video-based odometry system that enables trains to measure velocities and distances travelled without the need for trackside infrastructure. The Study Group was asked to investigate ways of improving the accuracy of such a system, and to suggest any improvements that might be made. The work performed in the week followed along these strands: (a). Elimination of errors in video odometery induced by pitch and height; (b) Robust calculation of (i) the train velocity and (ii) the track curvature; (c). Accurate determination of the position of a train on a track by assimilating Curvature information; (d). Determining where on UK’s railway map a train journey takes place, based purely on video odometry and (e). Drawing a track map

    Development of novel multiplex microsatellite polymerase chain reactions to enable high-throughput population genetic studies of Schistosoma haematobium

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    © 2015 Webster et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. The attached file is the published version of the article

    Phenotypic and genotypic monitoring of Schistosoma mansoni in Tanzanian schoolchildren five years into a preventative chemotherapy national control programme

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    We conducted combined in vitro PZQ efficacy testing with population genetic analyses of S. mansoni collected from children from two schools in 2010, five years after the introduction of a National Control Programme. Children at one school had received four annual PZQ treatments and the other school had received two mass treatments in total. We compared genetic differentiation, indices of genetic diversity, and estimated adult worm burden from parasites collected in 2010 with samples collected in 2005 (before the control programme began) and in 2006 (six months after the first PZQ treatment). Using 2010 larval samples, we also compared the genetic similarity of those with high and low in vitro sensitivity to PZQ

    Pattern Reduction in Paper Cutting

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    A large part of the paper industry involves supplying customers with reels of specified width in specifed quantities. These 'customer reels' must be cut from a set of wider 'jumbo reels', in as economical a way as possible. The first priority is to minimize the waste, i.e. to satisfy the customer demands using as few jumbo reels as possible. This is an example of the one-dimensional cutting stock problem, which has an extensive literature. Greycon have developed cutting stock algorithms which they include in their software packages. Greycon's initial presentation to the Study Group posed several questions, which are listed below, along with (partial) answers arising from the work described in this report. (1) Given a minimum-waste solution, what is the minimum number of patterns required? It is shown in Section 2 that even when all the patterns appearing in minimum-waste solutions are known, determining the minimum number of patterns may be hard. It seems unlikely that one can guarantee to find the minimum number of patterns for large classes of realistic problems with only a few seconds on a PC available. (2) Given an n → n-1 algorithm, will it find an optimal solution to the minimum- pattern problem? There are problems for which n → n - 1 reductions are not possible although a more dramatic reduction is. (3) Is there an efficient n → n-1 algorithm? In light of Question 2, Question 3 should perhaps be rephrased as 'Is there an efficient algorithm to reduce n patterns?' However, if an algorithm guaranteed to find some reduction whenever one existed then it could be applied iteratively to minimize the number of patterns, and we have seen this cannot be done easily. (4) Are there efficient 5 → 4 and 4 → 3 algorithms? (5) Is it worthwhile seeking alternatives to greedy heuristics? In response to Questions 4 and 5, we point to the algorithm described in the report, or variants of it. Such approaches seem capable of catching many higher reductions. (6) Is there a way to find solutions with the smallest possible number of single patterns? The Study Group did not investigate methods tailored specifically to this task, but the algorithm proposed here seems to do reasonably well. It will not increase the number of singleton patterns under any circumstances, and when the number of singletons is high there will be many possible moves that tend to eliminate them. (7) Can a solution be found which reduces the number of knife changes? The algorithm will help to reduce the number of necessary knife changes because it works by bringing patterns closer together, even if this does not proceed fully to a pattern reduction. If two patterns are equal across some of the customer widths, the knives for these reels need not be changed when moving from one to the other

    The origin of the Narrow Line Region of Mrk 3: an overpressured jet cocoon

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    We have obtained HST FOC long-slit optical spectroscopy of the Narrow Line Region of the Seyfert 2 galaxy Mrk 3. In the region cospatial with the radio-jet the velocity field is highly perturbed and shows two velocity systems separated by as much as 1700 km/s. We interpret this to be the consequence of the rapid expansion of a cocoon of hot gas, shocked and heated by the radio-emitting outflow, which compresses and accelerates the ambient gas. The NLR itself is essentially a cylindrical shell expanding supersonically. From the size and velocity of the expanding region, we derive an upper limit to the radio-source age, ~ 2 E42 erg/s required to inflate the cocoon and estimate that the jet minimum advance speed is 3 E-3 pc per year. The total kinetic energy of the high velocity NLR gas can be estimated as ~6 E54 erg, comparable to the total energy carried by the jet over its lifetime and this quantitatively supports the idea that the NLR gas is accelerated by the jet. If the advance speed of Mrk 3 is representative of the Seyfert population then these sources must also be short lived and probably recurrent. The jet kinetic luminosity of Mrk 3 is between 2 and 3 orders of magnitude smaller than that derived for radio-loud AGNs with similar emission-line luminosity. On the other hand, the fraction of jet power dissipated in radio-emission is similar. We speculate that the main distinction between radio-quiet and radio-loud AGN is ascribed to a difference in jet power rather than to a different efficiency in synchrotron emission production.Comment: 13 pages, 8 figures, Astrophysical Journal in pres

    Generating successive incomplete blocks with each pair of elements in at least one block

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    This paper examines solutions to the following combinatorial problem: Produce an ordered set of blocks of M elements chosen from N such that (i) any pair of the N elements occurs together in at least one block, and (ii) the total number of element changes in forming each new block from the previous one is minimised. For certain values of N and M, the only known solutions have no known generalisation. However, several general algorithms are described that produce sets of blocks satisfying (i) and either satisfying or nearly satisfying (ii). Other, related, combinatorial problems are outlined; all are relevant to organizing a certain type of data in a computer
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