36 research outputs found

    Interplay of spatial dynamics and local adaptation shapes species lifetime distributions and species-area relationships

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    The distributions of species lifetimes and species in space are related, since species with good local survival chances have more time to colonize new habitats and species inhabiting large areas have higher chances to survive local disturbances. Yet, both distributions have been discussed in mostly separate communities. Here, we study both patterns simultaneously using a spatially explicit, evolutionary community assembly approach. We present and investigate a metacommunity model, consisting of a grid of patches, where each patch contains a local food web. Species survival depends on predation and competition interactions, which in turn depend on species body masses as the key traits. The system evolves due to the migration of species to neighboring patches, the addition of new species as modifications of existing species, and local extinction events. The structure of each local food web thus emerges in a self-organized manner as the highly non-trivial outcome of the relative time scales of these processes. Our model generates a large variety of complex, multi-trophic networks and therefore serves as a powerful tool to investigate ecosystems on long temporal and large spatial scales. We find that the observed lifetime distributions and species-area relations resemble power laws over appropriately chosen parameter ranges and thus agree qualitatively with empirical findings. Moreover, we observe strong finite-size effects, and a dependence of the relationships on the trophic level of the species. By comparing our results to simple neutral models found in the literature, we identify the features that are responsible for the values of the exponents.Comment: Theor Ecol (2019

    On the interplay of speciation and dispersal: An evolutionary food web model in space

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    We introduce an evolutionary metacommunity of multitrophic food webs on several habitats coupled by migration. In contrast to previous studies that focus either on evolutionary or on spatial aspects, we include both and investigate the interplay between them. Locally, the species emerge, interact and go extinct according to the rules of the well-known evolutionary food web model proposed by Loeuille and Loreau in 2005. Additionally, species are able to migrate between the habitats. With random migration, we are able to reproduce common trends in diversity-dispersal relationships: Regional diversity decreases with increasing migration rates, whereas local diversity can increase in case of a low level of dispersal. Moreover, we find that the total biomasses in the different patches become similar even when species composition remains different. With adaptive migration, we observe species compositions that differ considerably between patches and contain species that are descendant from ancestors on both patches. This result indicates that the combination of spatial aspects and evolutionary processes affects the structure of food webs in different ways than each of them alone.Comment: under review at JT

    Reduced pituitary size in subjects with mutations in the THRB gene and thyroid hormone resistance.

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    BACKGROUND: Thyroid hormone action is mediated by two forms of thyroid hormone receptors (α, β) with differential tissue distribution. Thyroid hormone receptor β (TRβ) mutations lead to resistance to thyroid hormone action in tissues predominantly expressing the β form of the receptor (pituitary, liver). This study seeks to identify the effects of mutant TRβ on pituitary size. METHODS: High-resolution 3D T1-weighted magnetic resonance images were acquired in 19 patients with RTHβ in comparison to 19 healthy matched controls. Volumetric measurements of the pituitary gland were performed independently and blinded by four different raters (two neuroradiologists, one neurologist, one neuroscientist). RESULTS: Patients with mutant TRβ (resistance to thyroid hormone β, RTHβ) showed elevated free tri-iodothyronine/thyroxine levels with normal thyroid-stimulating hormone levels, whereas healthy controls showed normal thyroid hormone levels. Imaging revealed smaller pituitary size in RTHβ patients in comparison to healthy controls (F(1,35) = 7.05, P = 0.012, partial η2 = 0.17). CONCLUSION: RTHβ subjects have impaired sensitivity to thyroid hormones, along with decreased size of the pituitary gland

    Der König als Krieger. Zum Verhältnis von Königtum und Krieg im Mittelalter. Beiträge der Tagung des Zentrums für Mittelalterstudien der Otto-Friedrich-Universität Bamberg (13. – 15. März 2013)

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    Der König als Krieger – Zum Verhältnis von Königtum und Krieg im Mittelalter Kriegshandlungen waren in der mittelalterlichen Gesellschaft allgegenwärtig und oftmals eng mit dem Königtum verknüpft. Nahezu alle Könige des Mittelalters haben während ihrer Regierungszeit militärische Aktionen durchgeführt. Dabei agierten sie als Kriegsherren, militärische Anführer und immer wieder auch als aktive Kämpfer. Diese Rollen werden in den Quellen oft genug betont, etwa durch den gängigen Topos einer mitreißenden Rede unmittelbar vor der Schlacht. Gleichzeitig waren sich die Zeitgenossen jedoch der Bedeutung der persönlichen Unversehrtheit des Monarchen vollauf bewusst, womit ein Spannungsmoment zwischen der Herrschertugend der Tapferkeit (fortitudo) und der Raison des Königsamtes gegeben war. Der Sammelband analysiert anhand von verschiedenen historischen Beispielen, welche Bedeutung die Kriegsteilnahme für das mittelalterliche Herrschaftsverständnis hatte, wann, wie und in welchem Kontext die Rolle des Königs als Feldherr oder Kämpfer besonders hervorgehoben, wann sie unterdrückt oder kritisiert wurde

    Status demonstration of the interdisciplinary development regarding the upper limb exoskeleton "Stuttgart Exo-Jacket"

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    The prevention of work-related diseases is becoming increasingly important in industrial assembly and logistics. Musculoskeletal disorders are the most common type of disease for work disability days in Germany [1] and are particularly focused on demographic change in functional ergonomics concepts. Overhead activities, heavy lifting and working in non-ergonomic postures lead to diseases of the shoulder [2], which cause long off times of the workers [3]. In the first instance, the working process should go without additional tools at all. Therefore, ergonomic principles should be taken into account at the beginning of the value chain in the development and factory planning. Already existing non-ergonomic jobs with a high load on the worker’s body need functional alternatives. Body worn exoskeletons, as the Stuttgart Exo-Jacket should reduce load peaks during critical workflows and avoid diseases of the musculoskeletal system without restraining the work processes. In order to support the worker in his operations optimally, aspects from different disciplines have to be taken into account. The interdisciplinary development process of the Stuttgart Exo-Jacket is described in this article, focused on the requirements analysis and test methodology

    Relative importance of different climate policy elements for corporate climate innovation activities: findings for the power sector

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    This study investigates the relative importance of different climate policy elements for power sector companies’ investment decisions regarding “building of new plants” (adoption) and “research, development and demonstration” (RD&D). The climate policy elements examined are the EU Emission Trading System (EU ETS), as Europe’s core climate policy instrument, on the one hand, and long-term climate policy targets for 2020, on the other hand. These elements are compared to the relevance of other factors in the business environment, including other policies relevant for such investment decisions. Throughout the study the firms are differentiated along their value chain position, i.e. power generators (with at least one of their plants subject to the EU ETS) and technology providers (equipment manufacturers). The study pays particular attention to differences in firms’ technology portfolios and CO2 price expectations. The analysis is based on data from a survey conducted among European firms in November and December 2009

    Ethics in times of physical distancing: virtual training of ethical competences

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    Ethics teaching in medicine, nursing and other health care professions does not only consist of knowledge transfer that can be easily implemented digitally. Rather, it focuses on specific ethical competences (such as arguing and articulating one's own moral position) and attitudes (such as empathic patient orientation, critical self-reflection, and ambiguity tolerance), for whose development interactive formats are superior. Competence-oriented ethical learning goals are important for the development of professionalism, but require time, space and personal exchange. Due to contact restrictions and the widespread cancellation of (face-to-face) courses in the wake of the corona pandemic, ethics teaching was forced to keep its distance in many places, which posed great challenges. This article is based on an exchange of experiences from members of the working group ethik learning of the Academy for Ethics in Medicine about ethics teaching in times of physical distancing. Recommendations will be given on how ethical competence can be successfully taught in the context of exclusively digital teaching. Starting with the question what is at risk of being lost in digital teaching, the potentials of digital formats are explored and illustrated with concrete practical examples. Beyond ethics teaching, the article also aims to provide ideas and suggestions for other specialist and cross-sectional areas where interactive formats are central.Ethik-Lehre in Medizin, Pflege und anderen Gesundheitsberufen besteht nicht allein aus Wissensvermittlung, die digital gut umzusetzten ist. Im Mittelpunkt stehen vielmehr spezifische ethische Fertigkeiten (etwa Argumentieren und Artikulieren der eigenen moralischen Position) und Haltungen (etwa empathische Patientenorientierung, kritische Selbstreflexion und Ambiguitätstoleranz), für deren Entwicklung interaktive Formate besser geeignet sind. Kompetenzorientierte ethische Lernziele sind für die Entwicklung des professionellen Rollen- und Selbstverständnisses wichtig, erfordern jedoch Zeit, Raum und vor allem den persönlichen Austausch. Durch die Kontaktbeschränkungen und den fächendeckenden Ausfall von (Präsenz-)Lehrveranstaltungen im Zuge der Corona-Pandemie war die Ethik-Lehre vielerorts gezwungen, auf Abstand zu gehen, was grosse Herausforderungen mit sich brachte. Der Beitrag basiert auf einem Erfahrungsaustausch von Mitgliedern der Arbeitsgruppe ethik lerning der Fachgesellschaft Akademie für Ethik in der Medizin über Ethhik-Lehre in Zeiten von physical distancing. Es werden Empfehlungen gegeben, wie ethische Kompetenzvermittlung im Rahmen ausschliesslich digital stattfindender Lehre gelingen kann. Ausgehend davon, was bei digitalem Unterricht verlohren zu gehen droht, werden die Potentziale digitaler Formate ausgelotet und mit konkreten Praxisbeispielen illustriert. Über die Ethik-Lehre hinaus möchte der Beitrag auch Ideen und Anregungen für andere Fach-Querschnittsbereiche geben, bei denen interaktive Formate zentral sind.ISSN:2366-501

    Exoskelette in der Produktion und Reha - Bionische Aspekte bei der Entwicklung körpergetragener Robotik

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    The close co-operation between man and machine, man and robot, is manifested in an extreme way in exoskeletal systems, which are supported by the body, which are suppose actively or passively the movements of the human body. As a backdrop of support, the user has to accept the increased base load of the technical components and the restriction of the freedom of movement. With a new biomimetic approach the transfer of musculoskeletal structures to the “Stuttgart Exo-Jacket” significantly augments the user's freedom of movement and reduces the weight of the exoskeleton. The lightweight spine module, made from 3D printed plastic and the joint chain on the shoulder parts, which is leaned against the human spine and muscle parts, allows for most natural shoulders and back movements. Through the chain of artificial vertebral body modules and tensile rubber cables, the unhealthy flexion of the human spine during lifting can be effectively restricted. In this way, the user can freely move in the exoskeleton, but is supported by the exoskeleton with additional energy if necessary, for example when lifting heavy loads
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