10,470 research outputs found
Allo-triploid Sphagnum <sup>x</sup>falcatulum: single individuals contain most of the Holantarctic diversity for ancestrally indicative markers
No full textBackground and Aims. Allopolyploids exhibit both different levels and patterns of genetic variation than are typical of diploids. However, scant attention has been given to the partitioning of allelic information and diversity in allopolyploids, particularly that among homeologous monoploid components of the hologenome. Sphagnum ×falcatulum is a double allopolyploid peat moss that spans a considerable portion of the Holantarctic. With monoploid genomes from three ancestral species, this organism exhibits a complex evolutionary history involving serial inter-subgeneric allopolyploidizations.
Methods. Studying populations from three disjunct regions (South Island [New Zealand]; Tierra de Fuego archipelago [Chile, Argentia]; Tasmania [Australia]) we examine genetic information for five highly stable microsatellite markers that differ among the three (ancestral) monoploid genomes. We partition the holoploid information into separate components for individuals within and among single sites and regions, as well as within and among the three monoploid genomes, and then convert those information components into corresponding diversity measures.
Key Results. The majority (76%) of alleles detected across these five markers appear to have been captured by hybridization, but the information within each of the three monoploid genomes varied, suggesting a history of recurrent alloploidization between ancestral species containing different levels of genetic diversity. Information within individuals, equivalent to the information among monoploid genomes (for this dataset), was relatively stable, and represented 83% of the grand total information across the Holantarctic, with both inter-regional and inter-population diversification each accounting for about 5% of the total information.
Conclusions. Sphagnum ×falcatulum appears to have inherited the great majority of its genetic diversity at these markers by reticulation, rather than by subsequent evolutionary radiation. However, some post hybridization genetic diversification has become fixed in at least one regional population. Methodology allowing statistical analysis of any ploidy level is presented.Peer reviewed
Information Theory Broadens the Spectrum of Molecular Ecology and Evolution
No full textInformation or entropy analysis of diversity is used extensively in community ecology, and has recently been exploited for prediction and analysis in molecular ecology and evolution. Information measures belong to a spectrum (or ‘q-profile’) of measures whose contrasting properties provide a rich summary of diversity, including allelic richness (q=0), Shannon information (q=1), and heterozygosity (q=2). We present the merits of information measures for describing and forecasting molecular variation within and among groups, comparing forecasts with data, and evaluating underlying processes such as dispersal. Importantly, information measures directly link causal processes and divergence outcomes, have straightforward relationship to allele frequency differences (including monotonicity that q=2 lacks), and show additivity across hierarchical layers such as ecology, behaviour, cellular processes, and non-genetic inheritance.Peer reviewe
Surveying the experience of living with metastatic breast cancer: comparing face-to-face and online recruitment
No full textWith its growing use, the Internet offers researchers a novel approach in reaching those they seek to study locally, nationally or globally. The purpose of this paper is to describe our experience of using the Internet as one means of recruiting to a research study exploring the experience of women with metastatic breast cancer and to compare the methodological issues of using face-to-face and online approaches to survey recruitment. The survey incorporated the Functional Assessment of Cancer Therapy-Breast (FACT-B) quality of life measure, a patient experience with care measure and open ended text questions about respondents’ physical, emotional and practical needs. Recruitment was done face-to-face in two cancer centres and on the Breast Cancer Care (it is the UK’s leading provider of information, practical assistance and emotional support for anyone affected by breast cancer) Website, recruiting 110 people in the cancer centres and 125 from the Website. The age range was 25–84. Website respondents were significantly younger than cancer centre respondents (<0.000). They also had significantly lower social well-being on the FACT-B scale and were less satisfied with information and advice (<0.000) and their personal experience of care (<0.010). Finally, we consider the role of the Internet in research and the methodological and ethical challenges this presents both now and in the future
Influences of host community characteristics on Borrelia burgdorferi infection prevalence in Blacklegged ticks
No full textLyme disease is a major vector-borne bacterial disease in the USA. The disease is caused by Borrelia burgdorferi, and transmitted among hosts and humans, primarily by blacklegged ticks (Ixodes scapularis). The ~25 B. burgdorferi genotypes, based on genotypic variation of their outer surface protein C (ospC), can be phenotypically separated as strains that primarily cause human diseases – human invasive strains (HIS) – or those that rarely do – and are non-randomly associated with host species. The goal of this study was to examine the extent to which phenotypic outcomes of B. burgdorferi could be explained by the host communities fed upon by blacklegged ticks. In 2006 and 2009, we determined the host community composition based on abundance estimates of the vertebrate hosts, and collected host-seeking nymphal ticks in 2007 and 2010 to determine the ospC genotypes within infected ticks. We regressed instances of B. burgdorferi phenotypes on site-specific characteristics of host communities by constructing Bayesian hierarchical models that properly handled missing data. The models provided quantitative support for the relevance of host composition on Lyme disease risk pertaining to B. burgdorferi prevalence (i.e., overall nymphal infection prevalence, or NIPAll) and HIS prevalence among the infected ticks (NIPHIS). In 2006, we found positive associations of the relative abundances of mice, of chipmunks, and of shrews with NIPAll. We also found positive associations of NIPHIS with shrews, and with host community diversity (H’), but negative associations with mice, and with chipmunks. In 2009, the relative abundance of mice showed a positive association with NIPAll, whereas the relative abundance of shrews and of H’ showed a negative association. With NIPHIS, only H’ showed a positive association, whereas the relative abundances of mice, of chipmunks, and of shrews, had negative associations. Our study highlights the variability between two years in the effects of host composition on B. burgdorferi genotypes. More importantly, our results highlight how disease risk inference, based on the role of host community, changes when we examine risk overall or at the phenotypic level. Long-term studies will be necessary to detect any consistent effects of host community composition on genotypic variation in the Lyme disease spirochetes
Converting quadratic entropy to diversity: both animals and alleles are diverse, but some are more diverse than others
No full textThe use of diversity metrics has a long history in population ecology, while population genetic work has been dominated by variance-derived metrics instead, a technical gap that has slowed cross-communication between the fields. Interestingly, Rao’s Quadratic Entropy (RQE), comparing elements for ‘degrees of divergence’, was originally developed for population ecology, but has recently been deployed for evolutionary studies. We here translate RQE into a continuous diversity analogue, and then construct a multiply nested diversity partition for alleles, individuals, populations, and species, each component of which exhibits the behavior of proper diversity metrics, and then translate these components into [0,1] - scaled form. We also deploy non-parametric statistical tests of the among-stratum components and novel tests of the homogeneity of within-stratum diversity components at any hierarchical level. We then illustrate this new analysis with eight nSSR loci and a pair of close Australian marsupial (Antechinus) congeners, using both ‘different is different’ and ‘degree of difference’ distance metrics. The total diversity in the collection is larger than that within either species, but most of the within-species diversity is resident within single populations. The combined A. agilis collection exhibits more diversity than does the combined A. stuartii collection, possibly attributable to localized differences in either local ecological disturbance regimes or differential levels of population isolation. Beyond exhibiting different allelic compositions, the two congeners are becoming more divergent for the arrays of allele sizes they possess.The Antechinus data are archived in Excel workbook form, along with listings of the QDIVER results extracted from GenAlEx6.51 (http://biology.anu.edu.au/GenAlEx/). DC data and analyses are presented in S5 Appendix, and DR data and analyses are presented in S6 Appendix; these latter are ANU's to enable, and will be available with the paper as PLOS ONE access Supplements.Peer reviewe
The numerical modelling of rockbolts in geomechanics by finite element methods
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 15/03/1999.In tunnel excavation, the use of rockbolts has long been a popular means of reinforcement in rock masses to prevent the rock opening from caving in. The idea has evolved from the earliest form of rockbolt made of wood to the more up-to-date form of pre-tensioned or grouted steel rockbolts.
A major breakthrough in the design of rockbolt models was made by Aydan (1989). This rockbolt element was modelled in coupled form, with one sub-element representing the steel bolt, and the other sub-element the grout. This representation was necessary to model the complex action in the continuous rock mass near the joint.
In elasticity problems, the large displacement formulation of a beam element is derived from the fundamental theory, and the bending phenomenon of a thin rod is analysed by the finite element discretizations of the bar elements and the beam elements. Experiments show that the deformation characteristics of the latter representation resemble a more realistic life behaviour. Based on this finding, this thesis proposes a modification to Aydan's two-dimensional rockbolt element, with the beam elements discretising the steel bolt.
The different mechanical responses of a perfectly elastic rockbolt are considered, and the large displacement formulation of the new rockbolt element is derived by combining those of Aydan's rockbolt element and the beam element.
The mechanics of the Aydan element and the new rockbolt element are described, and their performances are compared in an identical situation. It is found that in the two two-dimensional examples used in this thesis, the modified element ensures the continuity of curvature of the rockbolt, and in general, can act as support across a discontinuity or joint between rock masses well.
In conjunction with the displacement method in the finite element procedures, a conventional iteration solution procedure is first described to solve the nonlinear incremental stiffness equation. However, it is found that this procedure is cumbersome, and requires a large amount of comptutations. Some limited storage quasi-Newton minimization algorithms are considered as an alternative
Church of Saints Peter and Paul
No full textSaints Peter and Paul Church; Church of Saints Peter and PaulChurch; BasilicaModern Baroque, FascistSan Pietro e Paolo; EUR Cathedral; SS Pietro e Paolo; Basilica de SS Pietro e Paolo; Santissimi Pietro e PaoloModeled on St. Peter's at the Vatican
Quality of life and experience of care in women with metastatic breast cancer: a cross-sectional survey
No full textContext: Despite developments in the medical management of metastatic breast cancer, little is known about the quality of life (QoL) and experience of care in women with it.Objectives: To explore QoL, experience of care, and support needs of women living with metastatic breast cancer in the U.K.Methods: Questionnaire-based, cross-sectional study, undertaken in two U.K. cancer centers and online via the Breast Cancer Care website, assessing QoL and experience of care in 235 women with metastatic breast cancer.Results: QoL was assessed using the Functional Assessment of Cancer Therapy—Breast QoL measure. Overall, QoL was low (mean 89.0, standard deviation 21.8) for total score. Low scores were seen uniformly in physical, social, emotional, and functional well-being domains. Symptom burden was a significant problem, with over one-third of women (34%) reporting high levels of pain and other uncontrolled symptoms. In multiple regression analysis, social well-being was significantly better for older women (P < 0.001) but was lower in those with bone metastases only (P = 0.002). Functional well-being was significantly higher in women without children (P = 0.004). Satisfaction with experience of care was low and appeared to be predominantly in the hospital setting, with little evidence of involvement of general practitioners and palliative care services.Conclusion: Despite improvements in treatment and survival of women with metastatic breast cancer, this group reports high symptom burden and dissatisfaction with elements of their care, indicating that alternative models of service delivery should be explored
Peter Templeman
No full textThe author describes Templeman's painting as being informed by the theories of Abstract Expressionism. Includes an artist's statement and biographical notes
Early hominin paleoecology
No full textEdited by Matt Sponheimer, Julia A. Lee-Thorp, Kaye E. Reed, and Peter Ungar.Includes bibliographical references and index.Pt. 1. Paleoclimate and paleoenvironment -- pt. 2. Hominin adaptations and behavior -- pt. 3. Analogies and models
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