263 research outputs found
A Crassigyrinus-like jaw from the Tournaisian (Early Mississippian) of Scotland
ABSTRACTThe early tetrapod Crassigyrinus scoticus was a large aquatic predator from the mid Carboniferous (late VisĂ©an or early Serpukovian) of Scotland, around 330 My in age. There are five main specimens with cranial remains: an articulated skeleton; two incomplete skulls; and two lower jaws. Crassigyrinus retains several apparently primitive features of the palatal dentition and lower jaw, and its phylogenetic position is disputed. A partial lower jaw resembling that of Crassigyrinus was discovered at Burnmouth in the Borders region of Scotland. The horizon in which it was found is dated as late Tournaisian, CM palynozone, around 350 My in age. Though it lacks dentition, the jaw preserves much of the postsplenial, angular and surangular, whose appearance externally and internally is almost identical to that of C. scoticus. Internally, the jaw shows a similarly limited extent of the suturing between the splenial series and the prearticular, a primitive condition. Externally, the type and distribution of dermal ornamentation closely matches that of C. scoticus, as does the deeply excavated and marginally positioned lateral line groove. As well as external and internal features, all specimens of C. scoticus are of similar skull size, though the Burnmouth jaw is somewhat smaller. If correctly attributable to Crassigyrinus, this specimen extends the existence of the genus by approximately 20 million years towards the base of the Carboniferous.LBP was funded by a Marie Curie International Incoming Research Fellowship (âTetrapods Risingâ, 300161), and for JAC and CEB by NERC
consortium grants NE/J022713/1 and NE/J020729/1 known as the TW:eed project. This is a contribution to IGCP project 596
Russia-UK collaboration in paleontology: past, present, and future
There is a long history of collaboration between Russia and the United Kingdom in paleontology. This began, arguably, in 1821, with the seminal work by William Fox-Strangways, who produced a geological map of the area around St Petersburg. Most famously, Roderick Murchison carried out extensive surveying and observations throughout European Russia in 1840 and 1841, and published a major monograph on geology and paleontology of European Russia in 1845. Since then, and continuing today, there have been many fruitful collaborations on Precambrian life, Paleozoic marine organisms, terrestrialization of plants and vertebrates, the PermianâTriassic mass extinction, fossil mammals, human evolution, and conservation paleobiology
Phylogenetic and environmental context of a Tournaisian tetrapod fauna
The end-Devonian to mid-Mississippian time interval has long been known for its depauperate palaeontological record, especially for tetrapods. This interval encapsulates the time of increasing terrestriality among tetrapods, but only two Tournaisian localities previously produced tetrapod fossils. Here we describe five new Tournaisian tetrapods (, , , and ) from two localities in their environmental context. A phylogenetic analysis retrieved three taxa as stem tetrapods, interspersed among Devonian and Carboniferous forms, and two as stem amphibians, suggesting a deep split among crown tetrapods. We also illustrate new tetrapod specimens from these and additional localities in the Scottish Borders region. The new taxa and specimens suggest that tetrapod diversification was well established by the Tournaisian. Sedimentary evidence indicates that the tetrapod fossils are usually associated with sandy siltstones overlying wetland palaeosols. Tetrapods were probably living on vegetated surfaces that were subsequently flooded. We show that atmospheric oxygen levels were stable across the Devonian/Carboniferous boundary, and did not inhibit the evolution of terrestriality. This wealth of tetrapods from Tournaisian localities highlights the potential for discoveries elsewhere.NERC consortium grants NE/J022713/1 (Cambridge), NE/J020729/1 (Leicester), NE/J021067/1 (BGS), NE/J020621/1 (NMS) and NE/J021091/1 (Southampton
High-temperature ferromagnetism of electrons in narrow impurity bands: Application to CaB
Ferromagnetism with high Curie temperature , well above room
temperature, and very small saturation moment has been reported in various
carbon and boron systems. It is argued that the magnetization must be very
inhomogeneous with only a small fraction of the sample ferromagnetically
ordered. It is shown that a possible source of high within the
ferromagnetic regions is itinerant electrons occupying a narrow impurity band.
Correlation effects do not reduce the effective interaction which enters the
Stoner criterion in the same way as in a bulk band. It is also shown how, in
the impurity band case, spin wave excitations may not be effective in lowering
below its value given by Stoner theory. These ideas are applied to
CaB and a thorough review of the experimental situation in this material is
given. It is suggested that the intrinsic magnetism of the B and O
dimers might be exploited in suitable structures containing these elements.Comment: 26 pages, 2 figure
Anatomical Network Comparison of Human Upper and Lower, Newborn and Adult, and Normal and Abnormal Limbs, with Notes on Development, Pathology and Limb Serial Homology vs. Homoplasy
How do the various anatomical parts (modules) of the animal body evolve into very different integrated forms (integration) yet still function properly without decreasing the individual's survival? This long-standing question remains unanswered for multiple reasons, including lack of consensus about conceptual definitions and approaches, as well as a reasonable bias toward the study of hard tissues over soft tissues. A major difficulty concerns the non-trivial technical hurdles of addressing this problem, specifically the lack of quantitative tools to quantify and compare variation across multiple disparate anatomical parts and tissue types. In this paper we apply for the first time a powerful new quantitative tool, Anatomical Network Analysis (AnNA), to examine and compare in detail the musculoskeletal modularity and integration of normal and abnormal human upper and lower limbs. In contrast to other morphological methods, the strength of AnNA is that it allows efficient and direct empirical comparisons among body parts with even vastly different architectures (e.g. upper and lower limbs) and diverse or complex tissue composition (e.g. bones, cartilages and muscles), by quantifying the spatial organization of these parts-their topological patterns relative to each other-using tools borrowed from network theory. Our results reveal similarities between the skeletal networks of the normal newborn/adult upper limb vs. lower limb, with exception to the shoulder vs. pelvis. However, when muscles are included, the overall musculoskeletal network organization of the upper limb is strikingly different from that of the lower limb, particularly that of the more proximal structures of each limb. Importantly, the obtained data provide further evidence to be added to the vast amount of paleontological, gross anatomical, developmental, molecular and embryological data recently obtained that contradicts the long-standing dogma that the upper and lower limbs are serial homologues. In addition, the AnNA of the limbs of a trisomy 18 human fetus strongly supports Pere Alberch's ill-named "logic of monsters" hypothesis, and contradicts the commonly accepted idea that birth defects often lead to lower integration (i.e. more parcellation) of anatomical structures
Childrenâs friendships in diverse primary schools: teachers and the processes of policy enactment
Drawing on data from a project exploring children's and adultsâ friendships across social class and ethnic difference, this paper focuses on the enactment of national and institutional policy around childrenâs friendships as realized in three primary schools in diverse urban areas in London. Through a focus on the way in which social and emotional learning (SEL) and teachersâ understandings of childrenâs friendships seek to govern childrenâs friendship behaviours, we turn to Foucaultâs work to explore how power shapes relations between policy frameworks and teachersâ practices, and between those who teach and those who are taught. We discuss the disciplinary potential of SEL and teachersâ âcommon senseâ understandings of childrenâs friendships, but conclude by noting possibilities for teachers to create spaces in which all children can safely explore the nature of friendships
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Implementation of infection prevention and control for hospitalized neonates: A narrative review.
BACKGROUND: The most prevalent infections encountered in neonatal care are healthcare-associated infections. The majority of healthcare-associated infections are considered preventable with evidence-based infection prevention and control (IPC) practices. However, substantial knowledge gaps exist in IPC implementation in neonatal care. Furthermore, the knowledge of factors which facilitate or challenge the uptake and sustainment of IPC programmes in neonatal units is limited. The integration of implementation science approaches in IPC programmes in neonatal care aims to address these problems. OBJECTIVES: The aim of this narrative review was to identify determinants which have been reported to influence the implementation of IPC programmes and best practices in inpatient neonatal care settings. SOURCES: A literature search was conducted in PubMed, MEDLINE (Medical Literature Analysis and Retrieval System Online) and CINAHL (Cumulative Index to Nursing and Allied Health Literature) in May 2022. Primary study reports published in English, French, German, Spanish, Portuguese, Italian, Danish, Swedish or Norwegian since 2000 were eligible for inclusion. Included studies focused on IPC practices in inpatient neonatal care settings and reported determinants which influenced implementation processes. CONTENT: The Consolidated Framework for Implementation Research was used to identify and cluster reported determinants to the implementation of IPC practices and programmes in neonatal care. Most studies reported challenges and facilitators at the organizational level as particularly relevant to implementation processes. The commonly reported determinants included staffing levels, work- and caseloads, as well as aspects of organizational culture such as communication and leadership. IMPLICATIONS: The presented knowledge about factors influencing neonatal IPC can support the design, implementation, and evaluation of IPC practices
Machine Learning in Automated Text Categorization
The automated categorization (or classification) of texts into predefined
categories has witnessed a booming interest in the last ten years, due to the
increased availability of documents in digital form and the ensuing need to
organize them. In the research community the dominant approach to this problem
is based on machine learning techniques: a general inductive process
automatically builds a classifier by learning, from a set of preclassified
documents, the characteristics of the categories. The advantages of this
approach over the knowledge engineering approach (consisting in the manual
definition of a classifier by domain experts) are a very good effectiveness,
considerable savings in terms of expert manpower, and straightforward
portability to different domains. This survey discusses the main approaches to
text categorization that fall within the machine learning paradigm. We will
discuss in detail issues pertaining to three different problems, namely
document representation, classifier construction, and classifier evaluation.Comment: Accepted for publication on ACM Computing Survey
Lived religion: Rethinking human nature in a neoliberal age
This article considers the relationship between philosophy of religion and an approach to the study of religion, which prioritises the experience of lived religion. Considering how individuals and communities live out their faith challenges some of the assumptions of analytic philosophers of religion regarding the position the philosopher should adopt when approaching the investigation of religion. If philosophy is understood principally as a means for analysing belief, it will have little space for an engagement with what it feels like to live out oneâs faith
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