2,351 research outputs found
Nest site selection by sea turtles
The distribution of 38 nests of loggerhead turtles (Caretta caretta) on beaches on Sanibel and Captiva islands, south-western Florida (26°26\u27N 82°16\u27W), and of 70 first digging attempts by green turtles (Chelonia mydas) on Ascension Island (7°57\u27S 14°22\u27W), was quantified. For loggerhead turtles on Sanibel and Captiva, nests were clumped close to the border between the open sand and the supra-littoral vegetation that backed the beaches. This spatial pattern of nests was closely reproduced by assuming simply that turtles crawled a random distance above the most recent high water line prior to digging. In contrast, green turtles on Ascension Island clumped their first digging attempts on the uneven beach above the springs high water line, crawling up to 80 m to reach this beach zone
Rapid identification of mutations in GJC2 in primary lymphoedema using whole exome sequencing combined with linkage analysis with delineation of the phenotype.
Background: Primary lymphoedema describes a chronic, frequently progressive, failure of lymphatic drainage. This disorder is frequently genetic in origin, and a multigenerational family in which eight individuals developed postnatal lymphoedema of all four limbs was ascertained from the joint Lymphoedema/Genetic clinic at St George's Hospital.
Methods: Linkage analysis was used to determine a locus, and exome sequencing was employed to look for causative variants.
Results: Linkage analysis revealed cosegregation of a 16.1 Mb haplotype on chromosome 1q42 that contained 173 known or predicted genes. Whole exome sequencing in a single affected individual was undertaken, and the search for the causative variant was focused to within the linkage interval. This approach revealed two novel non-synonymous single nucleotide substitutions within the chromosome 1 locus, in NVL and GJC2. NVL and GJC2 were sequenced in an additional cohort of individuals with a similar phenotype and non-synonymous variants were found in GJC2 in four additional families.
Conclusion: This report demonstrates the power of exome sequencing efficiently applied to a traditional positional cloning pipeline in disease gene discovery, and suggests that the phenotype produced by GJC2 mutations is predominantly one of 4 limb lymphoedema
The failed liberalisation of Algeria and the international context: a legacy of stable authoritarianism
The paper attempts to challenge the somewhat marginal role of international factors in the study of transitions to democracy. Theoretical and practical difficulties in proving causal mechanisms between international variables and domestic outcomes can be overcome by defining the international dimension in terms of Western dominance of world politics and by identifying Western actions towards democratising countries. The paper focuses on the case of Algeria, where international factors are key in explaining the initial process of democratisation and its following demise. In particular, the paper argues that direct Western policies, the pressures of the international system and external shocks influence the internal distribution of power and resources, which underpins the different strategies of all domestic actors. The paper concludes that analysis based purely on domestic factors cannot explain the process of democratisation and that international variables must be taken into more serious account and much more detailed
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The benefits of hedgerows for pollinators and natural enemies depends on hedge quality and landscape context
Ecological intensification advocates the harnessing of regulating and supporting ecosystem services to promote more sustainable food production, and this relies on effective management of non-cropped habitats. Hedgerows are an important component of the landscape in many farming systems across the world, management of which provides a potential mechanism to enhance ecological intensification. Here we investigate the value of hedgerows in Southern England as a source of functionally important taxa, and how hedgerow quality and local landscape composition impact on their potential contribution to sustainable agriculture in arable landscapes. We show that hedgerows are a source habitat for many natural enemies which spill over into neighbouring fields, and that hedgerows provide a valuable forage resource and corridor for movement of pollinators. Hedgerow quality affects these benefits and continuous unbroken hedgerows, with a high diversity of woody species, are more valuable for the provision of bumblebees and Linyphiid spiders, while the presence of trees within the hedgerow supports Lycosid spiders. Floral resources, beyond the woody hedgerow species themselves, are also a key forage resource for hoverflies. The impact of these hedgerows on invertebrate abundance is moderated by local landscape, and hedgerows are a more valuable forage resource for pollinators in more intensely managed landscapes. Our study shows that in order to support abundant and a broad range of natural enemies and pollinators in agricultural landscapes, both hedgerows and local semi-natural habitats need to be protected and managed. The benefit of hedgerows, as a habitat for functionally important taxa depends on hedgerow quality and management practices such as avoiding gaps, high hedge species diversity and maintaining an abundant understory of plants, can improve their value for ecological intensification
Validity and worth in the science curriculum: learning school science outside the laboratory
It is widely acknowledged that there are problems with school science in many developed countries of the world. Such problems manifest themselves in a progressive decline in pupil enthusiasm for school science across the secondary age range and the fact that fewer students are choosing to study the physical sciences at higher levels and as careers. Responses to these developments have included proposals to reform the curriculum, pedagogy and the nature of pupil discussion in science lessons. We support such changes but argue from a consideration of the aims of science education that secondary school science is too rooted in the science laboratory; substantially greater use needs to be made of out-of-school sites for the teaching of science. Such usage should result in a school science education that is more valid and more motivating and is better at fulfilling defensible aims of school science education. Our contention is that laboratory-based school science teaching needs to be complemented by out-of-school science learning that draws on the actual world (e.g. through fieldtrips), the presented world (e.g. in science centres, botanic gardens, zoos and science museums) and the virtual worlds that are increasingly available through information and communications technologies (ICT)
Coulomb-nuclear interference in the breakup of Be
Within a theory of breakup reactions formulated in the framework of the post
form distorted wave Born approximation, we calculate contributions of the pure
Coulomb and the pure nuclear breakup as well as those of their interference
terms to a variety of cross sections in breakup reactions of the one-neutron
halo nucleus Be on a number of target nuclei. In contrast to the
assumption often made, the Coulomb-nuclear interference terms are found to be
non-negligible in case of exclusive cross sections of the fragments emitted in
this reaction on medium mass and heavy target nuclei. The consideration of the
nuclear breakup leads to a better description of such data.Comment: 9 pages, latex, 2 figures, to be published in Phys. Rev. C (Rapid
Communication
Learning to Teach Argumentation: Research and development in the science classroom
The research reported in this study focuses on an investigation into the teaching of argumentation in secondary science classrooms. Over a one-year period, a group of 12 teachers from schools in the greater London area attended a series of workshops to develop materials and strategies to support the teaching of argumentation in scientific contexts. Data were collected at the beginning and end of the year by audio and video recording lessons where the teachers attempted to implement argumentation. To assess the quality of argumentation, analytical tools derived from Toulmin's argument pattern (TAP) were developed and applied to classroom transcripts. Analysis shows there was development in teachers' use of argumentation across the year. Results indicate that the pattern of use of argumentation is teacher-specific, as is the nature of change. To inform future professional development programmes, transcripts of five teachers, three showing a significant change and two no change, were analysed in more detail to identify features of teachers' oral contributions that facilitated and supported argumentation. The analysis showed that all teachers attempted to encourage a variety of processes involved in argumentation and that the teachers whose lessons included the highest quality of argumentation (TAP analysis) also encouraged higher order processes in their teaching. The analysis of teachers' facilitation of argumentation has helped to guide the development of in-service materials and to identify the barriers to learning in the professional development of less experienced teachers
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