245 research outputs found

    Body water conservation through selective brain cooling by the carotid rete: a physiological feature for surviving climate change?

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    Some mammals have the ability to lower their hypothalamic temperature below that of carotid arterial blood temperature, a process termed selective brain cooling. Although the requisite anatomical structure that facilitates this physiological process, the carotid rete, is present in members of the Cetartiodactyla, Felidae and Canidae, the carotid rete is particularly well developed in the artiodactyls, e.g. antelopes, cattle, sheep and goats. First described in the domestic cat, the seemingly obvious function initially attributed to selective brain cooling was that of protecting the brain from thermal damage. However, hyperthermia is not a prerequisite for selective brain cooling, and selective brain cooling can be exhibited at all times of the day, even when carotid arterial blood temperature is relatively low. More recently, it has been shown that selective brain cooling functions primarily as a water-conservation mechanism, allowing artiodactyls to save more than half of their daily water requirements. Here, we argue that the evolutionary success of the artiodactyls may, in part, be attributed to the evolution of the carotid rete and the resulting ability to conserve body water during past environmental conditions, and we suggest that this group of mammals may therefore have a selective advantage in the hotter and drier conditions associated with current anthropogenic climate change. A better understanding of how selective brain cooling provides physiological plasticity to mammals in changing environments will improve our ability to predict their responses and to implement appropriate conservation measures.EM201

    The impact of deep-sea fisheries and implementation of the UNGA Resolutions 61/105 and 64/72. Report of an international scientific workshop

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    The scientific workshop to review fisheries management, held in Lisbon in May 2011, brought together 22 scientists and fisheries experts from around the world to consider the United Nations General Assembly (UNGA) resolutions on high seas bottom fisheries: what progress has been made and what the outstanding issues are. This report summarises the workshop conclusions, identifying examples of good practice and making recommendations in areas where it was agreed that the current management measures fall short of their target

    What's wrong with the scrum laws in rugby union? - Judgment, truth and refereeing

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    Officiating and the role of officials in sport are crucial and often decisive factors in sports contests. Notable contributions in philosophy of sport include Collins (2012), Russell (1997; 1999), McFee (2011) & Mumford (2006) have brought a sharp philosophical focus to highlight that justice and desert of sport contests, in part, rely on officiating truths (performances) that arise from an appropriate admixture of epistemic (judgments) and metaphysical (actions) ingredients. This paper provides a rigorous and original philosophical analysis of the problems of obeying the rules and of applying the rules of sport. The paper focuses on a particular phase of play in rugby union, namely the scrum. It is fair to say that the scrum has become a focus of criticism and bewilderment. Elite televised rugby is damaged as a spectacle because too much time is wasted setting and re-setting scrums. Furthermore, our trust in the fairness of games is eroded because the scrum is a ‘lottery’ when it comes to officiating. In this paper, we identify two fundamental structural problems which contribute to the scrum controversy. First, drawing on Mumford (2006) and Collins (2012) we argue that officials cannot make reliable judgments about scrums because they cannot see what they need to see. Secondly, we argue that players cannot follow the laws of the scrum even if they have a strong desire to do so. Laws which can’t be followed are, according to Fuller (2000) defective. Consequently, the scrum is not only potentially dangerous but also flawed in terms of its capacity to actualize an intended part of the game

    Conformations of closed DNA

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    We examine the conformations of a model for a short segment of closed DNA. The molecule is represented as a cylindrically symmetric elastic rod with a constraint corresponding to a specification of the linking number. We obtain analytic expressions leading to the spatial configuration of a family of solutions representing distortions that interpolate between the circular form of DNA and a figure-eight form that represents the onset of interwinding. We are also able to generate knotted loops. We suggest ways to use our approach to produce other configurations relevant to studies of DNA structure. The stability of the distorted configurations is assessed, along with the effects of fluctuations on the free energy of the various configurations.Comment: 39 pages in REVTEX with 14 eps figures. Submitted to Phys. Rev. E. This manuscript updates, expands and revises, to a considerable extent, a previously posted manuscript, entitled "Conformations of Circular DNA," which appeared as cond-mat/970104

    Peak Stir Zone Temperatures during Friction Stir Processing

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    The stir zone (SZ) temperature cycle was measured during the friction stir processing (FSP) of NiAl bronze plates. The FSP was conducted using a tool design with a smooth concave shoulder and a 12.7-mm step-spiral pin. Temperature sensing was accomplished using sheathed thermocouples embedded in the tool path within the plates, while simultaneous optical pyrometry measurements of surface temperatures were also obtained. Peak SZ temperatures were 990 ⁰Cto 1015 ⁰C (0.90 to 0.97 TMelt) and were not affected by preheating to 400⁰C, although the dwell time above 900 ⁰C was increased by the preheating. Thermocouple data suggested little variation in peak temperature across the SZ, although thermocouples initially located on the advancing sides and at the centerlines of the tool traverses were displaced to the retreating sides, precluding direct assessment of the temperature variation across the SZ. Microstructure-based estimates of local peak SZ temperatures have been made on these and on other similarly processed materials. Altogether, the peak-temperature determinations from these different measurement techniques are in close agreement

    'Support our networking and help us belong!': listening to beginning secondary school science teachers

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    This study, drawing on the voice of beginning teachers, seeks to illuminate their experiences of building professional relationships as they become part of the teaching profession. A networking perspective was taken to expose and explore the use of others during the first three years of a teacher’s workplace experience. Three case studies, set within a wider sample of 11 secondary school science teachers leaving one UK university’s PostGraduate Certificate in Education, were studied. The project set out to determine the nature of the networks used by teachers in terms of both how they were being used for their own professional development and perceptions of how they were being used by others in school. Affordances and barriers to networking were explored using notions of identity formation through social participation. The focus of the paper is on how the teachers used others to help shape their sense of belonging to this, their new workplace. The paper develops ideas from network theories to argue that membership of the communities are a subset of the professional inter‐relationships teachers utilise for their professional development. During their first year of teaching, eight teachers were interviewed, completing 13 semi‐structured interviews. This was supplemented in Year 2 by a questionnaire survey of their experiences. In the third year of the programme, 11 teachers (including the original sample of eight) were surveyed using a network mapping tool in which they represented their communications with people, groups and resources. Finally, three of the teachers (common to both samples) were then interviewed specifically about their networking practices and experiences using the generation of their network map as a stimulated recall focus. The implications of the analysis of these accounts are that these beginning teachers did not perceive of themselves wholly as novices and that their personal aspirations to increase participation in practical science, develop a career or work for pupils holistically did not always sit comfortably with the school communities into which they were being accommodated. While highlighting the importance of trust and respect in establishing relationships, these teachers’ accounts highlight the importance of finding ‘peers’ from whom they can find support and with whom they can reflect and potentially collaborate towards developing practice. They also raise questions about who these ‘peers’ might be and where they might be found

    The impact of deep-sea fisheries and implementation of the UNGA Resolutions 61/105 and 64/72. Report of an international scientific workshop, National Oceanography Centre, Southampton

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    The scientific workshop to review fisheries management, held in Lisbon in May 2011, brought together 22 scientists and fisheries experts from around the world to consider the United Nations General Assembly (UNGA) resolutions on high seas bottom fisheries: what progress has been made and what the outstanding issues are. This report summarises the workshop conclusions, identifying examples of good practice and making recommendations in areas where it was agreed that the current management measures fall short of their target.Peer reviewe

    Elicitation of Potent Neutralizing Antibody Responses by Designed Protein Nanoparticle Vaccines for SARS-CoV-2

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    Walls et al. describe a potential nanoparticle vaccine for COVID-19, made of a self-assembling protein nanoparticle displaying the SARS-CoV-2 receptor-binding domain in a highly immunogenic array reminiscent of the natural virus. Their nanoparticle vaccine candidate elicits a diverse, potent, and protective antibody response, including neutralizing antibody titers 10-fold higher than the prefusion-stabilized spike ectodomain trimer

    The Physical Processes of CME/ICME Evolution

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    As observed in Thomson-scattered white light, coronal mass ejections (CMEs) are manifest as large-scale expulsions of plasma magnetically driven from the corona in the most energetic eruptions from the Sun. It remains a tantalizing mystery as to how these erupting magnetic fields evolve to form the complex structures we observe in the solar wind at Earth. Here, we strive to provide a fresh perspective on the post-eruption and interplanetary evolution of CMEs, focusing on the physical processes that define the many complex interactions of the ejected plasma with its surroundings as it departs the corona and propagates through the heliosphere. We summarize the ways CMEs and their interplanetary CMEs (ICMEs) are rotated, reconfigured, deformed, deflected, decelerated and disguised during their journey through the solar wind. This study then leads to consideration of how structures originating in coronal eruptions can be connected to their far removed interplanetary counterparts. Given that ICMEs are the drivers of most geomagnetic storms (and the sole driver of extreme storms), this work provides a guide to the processes that must be considered in making space weather forecasts from remote observations of the corona.Peer reviewe
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