2,365 research outputs found

    Soleus stretch reflex during cycling

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    The modulation and strength of the human soleus short latency stretch reflex was investigated by mechanically perturbing the ankle during an unconstrained pedaling task. Eight subjects pedaled at 60 rpm against a preload of 10 Nm. A torque pulse was applied to the crank at various positions during the crank cycle, producing ankle dorsiflexion perturbations of similar trajectory. The stretch reflex was greatest during the power phase of the crank cycle and was decreased to the level of background EMG during recovery. Matched perturbations were induced under static conditions at the same crank angle and background soleus EMG as recorded during the power phase of active pedaling. The magnitude of the stretch reflex was not statistically different from that during the static condition throughout the power phase of the movement. The results of this study indicate that the stretch reflex is not depressed during active cycling as has been shown with the H-reflex. This lack of depression may reflect a decreased susceptibility of the stretch reflex to inhibition, possibly originating from presynaptic mechanisms

    Octahedral Tilt Instability of ReO_3-type Crystals

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    The octahedron tilt transitions of ABX_3 perovskite-structure materials lead to an anti-polar (or antiferroelectric) arrangement of dipoles, with the low temperature structure having six sublattices polarized along various crystallographic directions. It is shown that an important mechanism driving the transition is long range dipole-dipole forces acting on both displacive and induced parts of the anion dipole. This acts in concert with short range repulsion, allowing a gain of electrostatic (Madelung) energy, both dipole-dipole and charge-charge, because the unit cell shrinks when the hard ionic spheres of the rigid octahedron tilt out of linear alignment.Comment: 4 page with 3 figures included; new version updates references and clarifies the argument

    Revealing lithium-silicide phase transformations in nano-structured silicon-based lithium ion batteries via in situ NMR spectroscopy.

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    Nano-structured silicon anodes are attractive alternatives to graphitic carbons in rechargeable Li-ion batteries, owing to their extremely high capacities. Despite their advantages, numerous issues remain to be addressed, the most basic being to understand the complex kinetics and thermodynamics that control the reactions and structural rearrangements. Elucidating this necessitates real-time in situ metrologies, which are highly challenging, if the whole electrode structure is studied at an atomistic level for multiple cycles under realistic cycling conditions. Here we report that Si nanowires grown on a conducting carbon-fibre support provide a robust model battery system that can be studied by (7)Li in situ NMR spectroscopy. The method allows the (de)alloying reactions of the amorphous silicides to be followed in the 2nd cycle and beyond. In combination with density-functional theory calculations, the results provide insight into the amorphous and amorphous-to-crystalline lithium-silicide transformations, particularly those at low voltages, which are highly relevant to practical cycling strategies.K.O acknowledges a research fellowship from Japanese Society for the Promotion of Science (JSPS). E.S acknowledges support by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme and thanks Churchill College (Cambridge, UK) for a non-stipendiary Raymond and Beverly Sackler Research fellowship. C.J.K and A.E.F acknowledge a research studentship from the Cambridge Nano Science and Technology Doctoral Training Centre (NanoDTC). A.J.M acknowledges the support from the Winton Programme for the Physics of Sustainability. S.H acknowledges funding from ERC grant InsituNANO (project number 279342). C.P.G and C.D thank the Royal Society, and C.P.G thanks European Research Council (ERC). C.P.G. acknowledges support from the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy, under Contract DE-AC02-05CH11231, subcontract 6952000.This is the accepted manuscript. The final version is available from Nature Communications at http://www.nature.com/ncomms/2014/140203/ncomms4217/full/ncomms4217.html

    In Silico Approaches and the Role of Ontologies in Aging Research

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    The 2013 Rostock Symposium on Systems Biology and Bioinformatics in Aging Research was again dedicated to dissecting the aging process using in silico means. A particular focus was on ontologies, as these are a key technology to systematically integrate heterogeneous information about the aging process. Related topics were databases and data integration. Other talks tackled modeling issues and applications, the latter including talks focussed on marker development and cellular stress as well as on diseases, in particular on diseases of kidney and skin

    Interviewer: 'Are women and girls ever responsible for the domestic violence they encounter?' Student: 'No, well, unless they did something really, really bad …'

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    Research shows the ‘gendered nature’ of domestic violence, with Women’s Aid (a UK-based charity) estimating that 1 in 4 women are affected (2014). This paper reports on a project - funded by Comic Relief, completed by Nottinghamshire Domestic Violence Forum (now known as Equation) and evaluated by Nottingham Trent University. The project adopts a Whole School Approach in seeking to prevent domestic violence. Students at three secondary schools attended between one and five blocks of work, and special events. There is evidence of positive developments - with young people showing understanding of domestic violence as well as the margins between healthy and unhealthy relationships. However, not all students could reply ‘never’ to the question of ‘are women and girls to blame for the domestic violence they experience?’, remarking that if the woman had done something ‘really, really bad’ then violence might be justified. We argue that young people’s uncertainties need to be situated within the gender-unequal socio-contexts of contemporary society, and further call for a WSA to domestic violence prevention to be a compulsory part of the UK national curriculum

    High-Rate Intercalation without Nanostructuring in Metastable Nb2O5 Bronze Phases.

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    Nanostructuring and nanosizing have been widely employed to increase the rate capability in a variety of energy storage materials. While nanoprocessing is required for many materials, we show here that both the capacity and rate performance of low-temperature bronze-phase TT- and T-polymorphs of Nb2O5 are inherent properties of the bulk crystal structure. Their unique "room-and-pillar" NbO6/NbO7 framework structure provides a stable host for lithium intercalation; bond valence sum mapping exposes the degenerate diffusion pathways in the sites (rooms) surrounding the oxygen pillars of this complex structure. Electrochemical analysis of thick films of micrometer-sized, insulating niobia particles indicates that the capacity of the T-phase, measured over a fixed potential window, is limited only by the Ohmic drop up to at least 60C (12.1 A·g(-1)), while the higher temperature (Wadsley-Roth, crystallographic shear structure) H-phase shows high intercalation capacity (>200 mA·h·g(-1)) but only at moderate rates. High-resolution (6/7)Li solid-state nuclear magnetic resonance (NMR) spectroscopy of T-Nb2O5 revealed two distinct spin reservoirs, a small initial rigid population and a majority-component mobile distribution of lithium. Variable-temperature NMR showed lithium dynamics for the majority lithium characterized by very low activation energies of 58(2)-98(1) meV. The fast rate, high density, good gravimetric capacity, excellent capacity retention, and safety features of bulk, insulating Nb2O5 synthesized in a single step at relatively low temperatures suggest that this material not only is structurally and electronically exceptional but merits consideration for a range of further applications. In addition, the realization of high rate performance without nanostructuring in a complex insulating oxide expands the field for battery material exploration beyond conventional strategies and structural motifs.K.J.G. gratefully acknowledges funding from The Winston Churchill Foundation of the United States and the Herchel Smith Scholarship. A.C.F. and J.M.G thank the EPSRC, via the Supergen consortium, for funding. A.C.F. is also thankful to the Sims Scholarship for support.This is the final version of the article. It first appeared in the American Chemical Society via http://dx.doi.org/10.1021/jacs.6b0434

    The institutional shaping of management: in the tracks of English individualism

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    Globalisation raises important questions about the shaping of economic action by cultural factors. This article explores the formation of what is seen by some as a prime influence on the formation of British management: individualism. Drawing on a range of historical sources, it argues for a comparative approach. In this case, the primary comparison drawn is between England and Scotland. The contention is that there is a systemic approach to authority in Scotland that can be contrasted to a personal approach in England. An examination of the careers of a number of Scottish pioneers of management suggests the roots of this systemic approach in practices of church governance. Ultimately this systemic approach was to take a secondary role to the personal approach engendered by institutions like the universities of Oxford and Cambridge, but it found more success in the different institutional context of the USA. The complexities of dealing with historical evidence are stressed, as is the value of taking a comparative approach. In this case this indicates a need to take religious practice as seriously as religious belief as a source of transferable practice. The article suggests that management should not be seen as a simple response to economic imperatives, but as shaped by the social and cultural context from which it emerges

    STS in management education: connecting theory and practice

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    This paper explores the value of science and technology studies (STS) to management education. The work draws on an ethnographic study of second year management undergraduates studying decision making. The nature and delivery of the decision making module is outlined and the value of STS is demonstrated in terms of both teaching method and module content. Three particular STS contributions are identified and described: the social construction of technological systems; actor network theory; and ontological politics. Affordances and sensibilities are identified for each contribution and a discussion is developed that illustrates how these versions of STS are put to use in management education. It is concluded that STS has a pivotal role to play in critical management (education) and in the process offers opportunities for new forms of managin
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