6,432 research outputs found

    Understanding the agility of running birds: Sensorimotor and mechanical factors in avian bipedal locomotion

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    Birds are a diverse and agile lineage of vertebrates that all use bipedal locomotion for at least part of their life. Thus birds provide a valuable opportunity to investigate how biomechanics and sensorimotor control are integrated for agile bipedal locomotion. This review summarizes recent work using terrain perturbations to reveal neuromechanical control strategies used by ground birds to achieve robust, stable and agile running. Early experiments in running guinea fowl aimed to reveal the immediate intrinsic mechanical response to an unexpected drop ('pothole') in terrain. When navigating the pothole, guinea fowl experience large changes in leg posture in the perturbed step, which correlates strongly with leg loading and perturbation recovery. Analysis of simple theoretical models of running has further confirmed the crucial role of swing-leg trajectory control for regulating foot contact timing and leg loading in uneven terrain. Coupling between body and leg dynamics results in an inherent trade-off in swing leg retraction rate for fall avoidance versus injury avoidance. Fast leg retraction minimizes injury risk, but slow leg retraction minimizes fall risk. Subsequent experiments have investigated how birds optimize their control strategies depending on the type of perturbation (pothole, step, obstacle), visibility of terrain, and with ample practice negotiating terrain features. Birds use several control strategies consistently across terrain contexts: 1) independent control of leg angular cycling and leg length actuation, which facilitates dynamic stability through simple control mechanisms, 2) feedforward regulation of leg cycling rate, which tunes foot-contact timing to maintain consistent leg loading in uneven terrain (minimizing fall and injury risks), 3) load-dependent muscle actuation, which rapidly adjusts stance push-off and stabilizes body mechanical energy, and 4) multi-step recovery strategies that allow body dynamics to transiently vary while tightly regulating leg loading to minimize risks of fall and injury. In future work, it will be interesting to investigate the learning and adaptation processes that allow animals to adjust neuromechanical control mechanisms over short and long timescales

    The story of Oh: the aesthetics and rhetoric of a common vowel sound

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    Studies in Musical Theatre is the only peer-reviewed journal dedicated to musical theatre. It was launched in 2007 and is now in its seventh volume. It has an extensive international readership and is edited by Dominic Symonds and George Burrows. This article investigates the use of the ‘word’ ‘Oh’ in a variety of different performance idioms. Despite its lack of ‘meaning’, the sound is used in both conversation and poetic discourse, and I discuss how it operates communicatively and expressively through contextual resonances, aesthetic manipulation and rhetorical signification. The article first considers the aesthetically modernist work of Cathy Berberian in Bussotti’s La Passion Selon Sade; then it considers the rhetorically inflected use of ‘Oh’ to construct social resonance in popular song;finally, it discusses two important uses of the sound ‘Oh’ which bookend the Broadway musical Oklahoma!, serving to consolidate the allegorical and musico-dramatic narrative of the show

    Quench dynamics and non equilibrium phase diagram of the Bose-Hubbard model

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    We investigate the time evolution of correlations in the Bose-Hubbard model following a quench from the superfluid to the Mott insulating phase. For large values of the final interaction strength the system approaches a distinctly non-equilibrium steady state that bears strong memory of the initial conditions. In contrast, when the final interaction strength is comparable to the hopping, the correlations are rather well approximated by those at thermal equilibrium. The existence of two distinct non-equilibrium regimes is surprising given the non-integrability of the Bose-Hubbard model. We relate this phenomena to the role of quasi-particle interactions in the Mott insulating state

    Quantum computing with alkaline earth atoms

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    We present a complete scheme for quantum information processing using the unique features of alkaline earth atoms. We show how two completely independent lattices can be formed for the 1^1S0_0 and 3^3P0_0 states, with one used as a storage lattice for qubits encoded on the nuclear spin, and the other as a transport lattice to move qubits and perform gate operations. We discuss how the 3^3P2_2 level can be used for addressing of individual qubits, and how collisional losses from metastable states can be used to perform gates via a lossy blockade mechanism.Comment: 4 pages, 3 figures, RevTeX

    The role of markets in food availability and market integration among smallholder farmers: the case of Western Kenya [Poster]

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    Poster presented at Tropentag 2013. International Research on Food Security, Natural Resource Management and Rural Development. "Agricultural development within the rural-urban continuum". Stuttgart-Hohenheim (Germany), Sep 17-19 2013

    First year student experience

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    The application was made on behalf of the undergraduate courses team who sought to enhance the first year experience by engaging students in the practice of business. The intention was to develop and signpost enterprising qualities and characteristics in first year learners and develop confidence as well as competence. The undergraduate review for FBL commenced in September 2009. This offered an opportunity to innovate and build good practice in enterprise learning as a pilot to inform the undergraduate review. The team sought to provide a coherent and relevant set of learning experiences that could be achieved outside structured curriculum that would enable learning through live projects

    Crop species diversity in smallholder farms in Western Kenya and their contribution to food security

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    Poster presented at First International Conference on Global Food Security. Noordwijkerhout (The Netherlands), 29 Sep - 02 Oct 2013

    Evangelistic Sermons

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    https://digitalcommons.acu.edu/crs_books/1406/thumbnail.jp

    American Indian Community Leader and Provider Views of Needs and Barriers to Colorectal Cancer Screening

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    Colorectal cancer is a great concern for the American Indian/Alaska Native (AI/AN) community, as incidence and mortality rates remain high and screening rates stay low. We conducted interviews with community leaders (n=13) and with providers from the Indian Health Service (IHS), tribal clinics, and urban safety-net clinics (n=17) in Northeast Kansas and the Kansas City Metro Area to determine their understanding of needs and barriers to colorectal cancer screening among American Indians. Using a community-based participatory research (CBPR) approach for this pilot study, community leaders and providers identified similar needs, including: culturally-appropriate education about colorectal cancer and screenings, the potential use of Native elders as patient navigators, and an emphasis on preventive care, particularly through the IHS. Barriers included culturally specific issues such as historic mistrust and gender roles. Other barriers are similar to members of other ethnic groups, such as cost, transportation, fear, and repulsion toward the screening process

    Crafty Entanglements: Knitting and Hard Distinctions in Aesthetics and Political Theory

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    Many theoretical writings on aesthetics and politics rely on hard distinctions between what is and is not art, and what is and is not political. In this article, I draw on the work of theorists, knitters, and fiber artists to argue that hand knitting provides a lens through which to unsettle some of these distinctions. I illustrate some of the ways in which aesthetic theory relies on hard distinctions between art and not-art and politics and not-politics, with particular focus on the work of Kant, Hegel, Heidegger, and Rancière. I explain how knitting is often seen as falling clearly outside the definitions of art and politics, and explore the surprising ways in which knitting shows the instability of these categories and expectations. I show that common social traditions and practices that often go unanalyzed can provide insight into the limitations and complexities of prevalent theoretical assumption
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