2,896 research outputs found

    Evolution of mitochondrial and nuclear genomes in Pennatulacea

    Get PDF
    We examine the phylogeny of sea pens using sequences of whole mitochondrial genomes and the nuclear ribosomal cluster generated through low coverage Illumina sequencing. Taxon sampling includes 30 species in 19 genera representing 13 families. Ancestral state reconstruction shows that most sea pen mitochondrial genomes have the ancestral gene order, and that Pennatulacea with diverse gene orders are found in a single clade. The monophyly of Pennatulidae and Protoptilidae are rejected by both the mitochondrial and nuclear dataset, while the mitochondrial dataset further rejects monophyly of Virgulariidae, and the nuclear dataset rejects monophyly of Kophobelemnidae. We show discordance between nuclear ribosomal gene cluster phylogenies and whole mitochondrial genome phylogenies and highlight key Pennatulacea taxa that could be included in cnidarian genome-wide studies to better resolve the sea pen tree of life. We further illustrate how well frequently sequenced markers capture the overall diversity of the mitochondrial genome and the nuclear ribosomal genes in sea pens

    The Concept of Culture in Critical Mathematics Education

    Get PDF
    © Springer International Publishing AG, part of Springer Nature 2018. This is a post-peer-review, pre-copyedit version of a chapter published in The Philosophy of Mathematics Education Today. The final authenticated version is available online at: http://dx.doi.org/10.1007/978-3-319-77760-3A well-known critique in the research literature of critical mathematics education suggests that framing educational questions in cultural terms can encourage ethnic-cultural essentialism, obscure conflicts within cultures and promote an ethnographic or anthropological stance towards learners. Nevertheless, we believe that some of the obstacles to learning mathematics are cultural. ‘Stereotype threat’, for example, has a basis in culture. Consequently, the aims of critical mathematics education cannot be seriously pursued without including a cultural approach in educational research. We argue that an adequate conception of culture is available and should include normative/descriptive and material/ideal dyads as dialectical moments

    Amnesic Patients Show Superior Generalization in Category Learning

    Get PDF
    OBJECTIVE: Generalization is the application of existing knowledge to novel situations. Questions remain about the precise role of the hippocampus in this facet of learning, but a connectionist model by Gluck and Myers (1993) predicts that generalization should be enhanced following hippocampal damage. METHOD: In a two-category learning task, a group of amnesic patients (n=9) learned the training items to a similar level of accuracy as matched controls (n=9). Both groups then classified new items at various levels of distortion. RESULTS: The amnesic group showed significantly more accurate generalization to high-distortion novel items, a difference also present when compared to a larger group of unmatched controls (n=33). CONCLUSIONS: The model prediction of a broadening of generalization gradients in amnesia, at least for items near category boundaries, was supported by the results. Our study shows for the first time that amnesia can sometimes improve generalization

    The role of external broadcasting in a closed political system

    Get PDF
    This article investigates the role and impact of external broadcasting (radio and television) on a closed political system, through the example of the two post-war German states: the West German Federal Republic of Germany (FRG) and the East German German Democratic Republic (GDR). The aim is to debunk myths about the influence of external broadcasting on the events that led to German reunification in 1990. The study follows a historical approach and discusses what role external media played during the years of a divided Germany. The findings are based on several historical sources, research reports from the 1950s and 1960s and over 100 biographical interviews with former residents of the German Democratic Republic (GDR). The article analyses the impact of external broadcasting on citizens and the political elite in times of crisis as well as during everyday life

    Phylogenetics and Mitogenome Organisation in Black Corals (Anthozoa: Hexacorallia: Antipatharia): An Order-Wide Survey Inferred From Complete Mitochondrial Genomes

    Get PDF
    Black corals (Anthozoa: Antipatharia) are an ecologically and culturally important group of deep-sea cnidarians. However, as the majority of species inhabit depths >50 m, they are relatively understudied. The inaccessibility of well-preserved tissue for species of interest has limited the scope of molecular analysis, and as a result only a small number of antipatharian mitochondrial genomes have been published. Using next generation sequencing, 18 complete and five partial antipatharian mitochondrial genomes were assembled, increasing the number of complete mitochondrial genomes to 22. This includes species from six antipatharian families, four of which were previously unrepresented, enabling the first family-level, full mitochondrial gene analysis over the whole order. The circular mitogenomes ranged in size from 17,681 to 21,669 bp with the large range in size due to the addition of an intron in COX1 in some species and size variation of intergenic regions. All mitogenomes contained the genes standard to all hexacoral mitogenomes (13 protein coding genes, two rRNAs and two tRNAs). The only difference in gene content is the presence of the COX1 intron in five families. The most variable mitochondrial gene is ND4 which may have implications for future barcoding studies. Phylogenetic analysis confirms that Leiopathidae is sister to all other families. Families Antipathidae, Cladopathidae and Schizopathidae are polyphyletic, supporting previous studies that call for a taxonomic revision

    Dissolution Dominates Silica Cycling in a Shelf Sea Autumn Bloom

    Get PDF
    Autumn phytoplankton blooms represent key periods of production in temperate and high‐latitude seas. Biogenic silica (bSiO2) production, dissolution, and standing stocks were determined in the Celtic Sea (United Kingdom) during November 2014. Dissolution rates were in excess of bSiO2 production, indicating a net loss of bSiO2. Estimated diatom bSiO2 contributed ≀10% to total bSiO2, with detritalbSiO2 supportingrapidSicycling.Basedontheaveragebiomass‐speciïŹcdissolutionrate(0.2day−1), 3weekswouldbeneededtodissolve99%ofthebSiO2 present.NegativenetbSiO2 productionwasassociated with low‐light conditions (<4 E·m−2·day−1). Our observations imply that dissolution dominates Si cycling during autumn, with low‐light conditions also likely to inïŹ‚uence Si cycling during winter and early spring

    Consensus of travel direction is achieved by simple copying, not voting, in free-ranging goats

    Get PDF
    For group-living animals to remain cohesive they must agree on where to travel. Theoretical models predict shared group decisions should be favoured, and a number of empirical examples support this. However, the behavioural mechanisms that underpin shared decision-making are not fully understood. Groups may achieve consensus of direction by active communication of individual preferences (i.e. voting), or by responding to each other's orientation and movement (i.e. copying). For example, African buffalo (Syncerus caffer) are reported to use body orientation to vote and indicate their preferred direction to achieve a consensus on travel direction, while golden shiners (Notemigonus crysoleucas) achieve consensus of direction by responding to the movement cues of their neighbours. Here, we present a conceptual model (supported by agent-based simulations) that allows us to distinguish patterns of motion that represent voting or copying. We test our model predictions using high-resolution GPS and magnetometer data collected from a herd of free-ranging goats (Capra aegagrus hircus) in the Namib Desert, Namibia. We find that decisions concerning travel direction were more consistent with individuals copying one another's motion and find no evidence to support the use of voting with body orientation. Our findings highlight the role of simple behavioural rules for collective decision-making by animal groups

    Short-Term Evaluation of Cellular Fate in an Ovine Bone Formation Model.

    Get PDF
    The ovine critical-sized defect model provides a robust preclinical model for testing tissue-engineered constructs for use in the treatment of non-union bone fractures and severe trauma. A critical question in cell-based therapies is understanding the optimal therapeutic cell dose. Key to defining the dose and ensuring successful outcomes is understanding the fate of implanted cells, e.g., viability, bio-distribution and exogenous infiltration post-implantation. This study evaluates such parameters in an ovine critical-sized defect model 2 and 7 days post-implantation. The fate of cell dose and behaviour post-implantation when combined with nanomedicine approaches for multi-model tracking and remote control using external magnetic fields is also addressed. Autologous STRO-4 selected mesenchymal stromal cells (MSCs) were labelled with a fluorescent lipophilic dye (CM-Dil), functionalised magnetic nanoparticles (MNPs) and delivered to the site within a naturally derived bone extracellular matrix (ECM) gel. Encapsulated cells were implanted within a critical-sized defect in an ovine medial femoral condyle and exposed to dynamic gradients of external magnetic fields for 1 h per day. Sheep were sacrificed at 2 and 7 days post-initial surgery where ECM was harvested. STRO-4-positive (STRO-4+) stromal cells expressed osteocalcin and survived within the harvested gels at day 2 and day 7 with a 50% loss at day 2 and a further 45% loss at 7 days. CD45-positive leucocytes were also observed in addition to endogenous stromal cells. No elevation in serum C-reactive protein (CRP) or non-haem iron levels was observed following implantation in groups containing MNPs with or without magnetic field gradients. The current study demonstrates how numbers of therapeutic cells reduce substantially after implantation in the repair site. Cell death is accompanied by enhanced leucocyte invasion, but not by inflammatory blood marker levels. Crucially, a proportion of implanted STRO-4+ stromal cells expressed osteocalcin, which is indicative of osteogenic differentiation. Furthermore, MNP labelling did not alter cell number or result in a further deleterious impact on stromal cells following implantation

    Novel diversity in mitochondrial genomes of deep-sea Pennatulacea (Cnidaria: Anthozoa: Octocorallia)

    Get PDF
    We present the first documented complete mitogenomes of deep-sea Pennatulacea, representing nine genera and eight families. These include one species each of the deep-sea genera Funiculina, Halipteris, Protoptilum and Distichoptilum, four species each of Umbellula and Pennatula, three species of Kophobelemnon and two species of Anthoptilum, as well as one species of the epi- and mesobenthic genus Virgularia. Seventeen circular genomes ranged from 18,513 bp (Halipteris cf. finmarchica) to 19,171 bp (Distichoptilum gracile) and contained all genes standard to octocoral mitochondrial genomes (14 protein-coding genes, two ribosomal RNA genes and one transfer RNA). We found at least three different gene orders in Pennatulacea: the ancestral gene order, the gene order found in bamboo corals (Family Isididae), and a novel gene order. The mitogenome of one species of Umbellula has a bipartite genome (∌13 kbp and ∌5 kbp), with good evidence that both parts are circular

    Galaxy And Mass Assembly (GAMA): A forensic SED reconstruction of the cosmic star-formation history and metallicity evolution by galaxy type

    Get PDF
    We apply the spectral energy distribution-fitting code ProSpect to multiwavelength imaging for ∌\sim7,000 galaxies from the GAMA survey at z<0.06z<0.06, in order to extract their star-formation histories. We combine a parametric description of the star formation history with a closed-box evolution of metallicity where the present-day gas-phase metallicity of the galaxy is a free parameter. We show with this approach that we are able to recover the observationally-determined cosmic star formation history (CSFH), an indication that stars are being formed in the correct epoch of the Universe, on average, for the manner in which we are conducting SED fitting. We also show the contribution to the CSFH of galaxies of different present-day visual morphologies, and stellar masses. This analysis suggests that half of the mass in present-day elliptical galaxies was in place 11 Gyr ago, whereas in other morphological types the stellar mass formed later, up to 6 Gyr ago for present-day irregular galaxies. Similarly, the most massive galaxies in our sample were shown to have formed half their stellar mass by 10.5 Gyr ago, whereas the least massive galaxies formed half their stellar mass as late as 4 Gyr ago (the well-known effect of "galaxy downsizing"). Finally, our metallicity approach allows us to follow the average evolution in gas-phase metallicity for populations of galaxies, and extract the evolution of the cosmic metal mass density in stars and in gas, producing results in broad agreement with observations of metal densities in the Universe
    • 

    corecore